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Sample records for acetazolamide methazolamide ethoxzolamide

  1. Acetazolamide-responsive ataxia.

    PubMed

    Kotagal, Vikas

    2012-11-01

    Acetazolamide-responsive ataxia represents a unique collection of genetically distinct episodic ataxia (EA) disorders associated with paroxysmal cerebellar symptoms many of which are responsive to medical treatment with acetazolamide, a carbonic anhydrase inhibitor. Among all of the subtypes of episodic ataxia, types 2 (EA2), 3 (EA3), and 5 (EA5) are thought be the most medication responsive. Some patients with episodic ataxia type 1 (EA1) will also describe improvement with acetazolamide. Each of these individual genetic syndromes is characterized by its own unique mechanism and clinical presentation. In this review, the author provides an overview of the pathophysiology of acetazolamide-responsive ataxia, its natural history, and its clinical management.

  2. Methazolamide Plus Aminophylline Abrogates Hypoxia-Mediated Endurance Exercise Impairment.

    PubMed

    Scalzo, Rebecca L; Binns, Scott E; Klochak, Anna L; Giordano, Gregory R; Paris, Hunter L R; Sevits, Kyle J; Beals, Joseph W; Biela, Laurie M; Larson, Dennis G; Luckasen, Gary J; Irwin, David; Schroeder, Thies; Hamilton, Karyn L; Bell, Christopher

    2015-12-01

    In hypoxia, endurance exercise performance is diminished; pharmacotherapy may abrogate this performance deficit. Based on positive outcomes in preclinical trials, we hypothesized that oral administration of methazolamide, a carbonic anhydrase inhibitor, aminophylline, a nonselective adenosine receptor antagonist and phosphodiesterase inhibitor, and/or methazolamide combined with aminophylline would attenuate hypoxia-mediated decrements in endurance exercise performance in humans. Fifteen healthy males (26 ± 5 years, body-mass index: 24.9 ± 1.6 kg/m(2); mean ± SD) were randomly assigned to one of four treatments: placebo (n = 9), methazolamide (250 mg; n = 10), aminophylline (400 mg; n = 9), or methazolamide (250 mg) with aminophylline (400 mg; n = 8). On two separate occasions, the first in normoxia (FIO2 = 0.21) and the second in hypoxia (FIO2 = 0.15), participants sat for 4.5 hours before completing a standardized exercise bout (30 minutes, stationary cycling, 100 W), followed by a 12.5-km time trial. The magnitude of time trial performance decrement in hypoxia versus normoxia did not differ between placebo (+3.0 ± 2.7 minutes), methazolamide (+1.4 ± 1.7 minutes), and aminophylline (+1.8 ± 1.2 minutes), all with p > 0.09; however, the performance decrement in hypoxia versus normoxia with methazolamide combined with aminophylline was less than placebo (+0.6 ± 1.5 minutes; p = 0.01). This improvement may have been partially mediated by increased SpO2 in hypoxia with methazolamide combined with aminophylline compared with placebo (73% ± 3% vs. 79% ± 6%; p < 0.02). In conclusion, coadministration of methazolamide and aminophylline may promote endurance exercise performance during a sojourn at high altitude.

  3. Methazolamide improves neurological behavior by inhibition of neuron apoptosis in subarachnoid hemorrhage mice

    PubMed Central

    Li, Mingchang; Wang, Wei; Mai, Haojian; Zhang, Xinmu; Wang, Jian; Gao, Yufeng; Wang, Yuefei; Deng, Gang; Gao, Ling; Zhou, Shuanhu; Chen, Qianxue; Wang, Xin

    2016-01-01

    Subarachnoid hemorrhage (SAH) results in significant nerve dysfunction, such as hemiplegia, mood disorders, cognitive and memory impairment. Currently, no clear measures can reduce brain nerve damage. The study of brain nerve protection after SAH is of great significance. We aim to evaluate the protective effects and the possible mechanism of methazolamide in C57BL/6J SAH animal model in vivo and in blood-induced primary cortical neuron (PCNs) cellular model of SAH in vitro. We demonstrate that methazolamide accelerates the recovery of neurological damage, effectively relieves cerebral edema, and improves cognitive function in SAH mice as well as offers neuroprotection in blood- or hemoglobin-treated PCNs and partially restores normal neuronal morphology. In addition, western blot analyses show obviously decreased expression of active caspase-3 in methazolamide-treated SAH mice comparing with vehicle-treated SAH animals. Furthermore, methazolamide effectively inhibits ROS production in PCNs induced by blood exposure or hemoglobin insult. However, methazolamide has no protective effects in morality, fluctuation of cerebral blood flow, SAH grade, and cerebral vasospasm of SAH mice. Given methazolamide, a potent carbonic anhydrase inhibitor, can penetrate the blood–brain barrier and has been used in clinic in the treatment of ocular conditions, it provides potential as a novel therapy for SAH. PMID:27731352

  4. 21 CFR 520.44 - Acetazolamide sodium soluble powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Acetazolamide sodium soluble powder. 520.44... Acetazolamide sodium soluble powder. (a) Specifications. The drug is in a powder form containing acetazolamide sodium, USP equivalent to 25 percent acetazolamide activity. (b) Sponsor. See No. 053501 in §...

  5. 21 CFR 520.44 - Acetazolamide sodium soluble powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acetazolamide sodium soluble powder. 520.44... Acetazolamide sodium soluble powder. (a) Specifications. The drug is in a powder form containing acetazolamide sodium, USP equivalent to 25 percent acetazolamide activity. (b) Sponsor. See No. 053501 in §...

  6. 21 CFR 522.44 - Sterile sodium acetazolamide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sterile sodium acetazolamide. 522.44 Section 522....44 Sterile sodium acetazolamide. (a) Specifications. Sterile sodium acetazolamide contains acetazolamide sodium complying with United States Pharmacopeia as a sterile powder with directions...

  7. 21 CFR 522.44 - Sterile sodium acetazolamide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sterile sodium acetazolamide. 522.44 Section 522....44 Sterile sodium acetazolamide. (a) Specifications. Sterile sodium acetazolamide contains acetazolamide sodium complying with United States Pharmacopeia as a sterile powder with directions...

  8. 21 CFR 520.44 - Acetazolamide sodium soluble powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Acetazolamide sodium soluble powder. 520.44... Acetazolamide sodium soluble powder. (a) Specifications. The drug is in a powder form containing acetazolamide sodium, USP equivalent to 25 percent acetazolamide activity. (b) Sponsor. See No. 053501 in §...

  9. Carbonic anhydrase and control of breathing: different effects of benzolamide and methazolamide in the anaesthetized cat.

    PubMed Central

    Teppema, L; Berkenbosch, A; DeGoede, J; Olievier, C

    1995-01-01

    1. The effect of inhibition of erythrocyte carbonic anhydrase on the ventilatory response to CO2 was studied by administering benzolamide (70 mg kg-1, i.v.), an inhibitor which does not cross the blood-brain barrier, to carotid body denervated cats which were anaesthetized with chloralose-urethane. 2. In the same animals the effect on the ventilatory response to CO2 of subsequent inhibition of central nervous system (CNS) carbonic anhydrase was studied by infusing methazolamide (20 mg kg-1), an inhibitor which rapidly penetrates into brain tissue. 3. The results show that inhibition of erythrocyte carbonic anhydrase by benzolamide leads to a decrease in the slope of the normoxic CO2 response curve, and a decrease of the extrapolated arterial PCO2 at zero ventilation. 4. Inhibition of CNS carbonic anhydrase by methazolamide results in an increase in slope and alpha-intercept of the ventilatory CO2 response curve. 5. Using a mass balance equation for CO2 of a brain compartment, it is argued that inhibition of erythrocyte carbonic anhydrase results in a decrease in slope of the in vivo CO2 dissociation curve, which can explain the effects of benzolamide. 6. The changes in slope and intercept induced by methazolamide are discussed in relation to effects on neurones containing carbonic anhydrase, which may include central chemoreceptors. PMID:8576866

  10. Neutron structure of human carbonic anhydrase II in complex with methazolamide: mapping the solvent and hydrogen-bonding patterns of an effective clinical drug

    DOE PAGES

    Aggarwal, Mayank; Kovalevsky, Andrey Y.; Velazquez, Hector; ...

    2016-07-22

    Carbonic anhydrases (CAs; EC 4.2.1.1) catalyze the interconversion of CO 2 and HCO 3 − , and their inhibitors have long been used as diuretics and as a therapeutic treatment for many disorders such as glaucoma and epilepsy. Acetazolamide (AZM) and methazolamide (MZM, a methyl derivative of AZM) are two of the classical CA inhibitory drugs that have been used clinically for decades. The jointly refined X-ray/neutron structure of MZM in complex with human CA isoform II (hCA II) has been determined to a resolution of 2.2 Å with an R cryst of ∼16.0%. Presented in this article, along withmore » only the second neutron structure of a clinical drug-bound hCA, is an in-depth structural comparison and analyses of differences in hydrogen-bonding network, water-molecule orientation and solvent displacement that take place upon the binding of AZM and MZM in the active site of hCA II. Even though MZM is slightly more hydrophobic and displaces more waters than AZM, the overall binding affinity ( K i ) for both of the drugs against hCA II is similar (∼10 n M ). The plausible reasons behind this finding have also been discussed using molecular dynamics and X-ray crystal structures of hCA II–MZM determined at cryotemperature and room temperature. This study not only allows a direct comparison of the hydrogen bonding, protonation states and solvent orientation/displacement of AZM and MZM, but also shows the significant effect that the methyl derivative has on the solvent organization in the hCA II active site.« less

  11. Single and mixed poloxamine micelles as nanocarriers for solubilization and sustained release of ethoxzolamide for topical glaucoma therapy

    PubMed Central

    Ribeiro, Andreza; Sosnik, Alejandro; Chiappetta, Diego A.; Veiga, Francisco; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2012-01-01

    Polymeric micelles of single and mixed poloxamines (Tetronic) were evaluated regarding their ability to host the antiglaucoma agent ethoxzolamide (ETOX) for topical ocular application. Three highly hydrophilic varieties of poloxamine (T908, T1107 and T1307) and a medium hydrophilic variety (T904), possessing a similar number of propylene oxide units but different contents in ethylene oxide, were chosen for the study. The critical micellar concentration and the cloud point of mixed micelles in 0.9 per cent NaCl were slightly greater than the values predicted from the additive rule, suggesting that the co-micellization is hindered. Micellar size ranged between 17 and 120 nm and it was not altered after the loading of ETOX (2.7–11.5 mg drug g–1 poloxamine). Drug solubilization ability ranked in the order: T904 (50-fold increase in the apparent solubility) > T1107 ≅ T1307 > T908. Mixed micelles showed an intermediate capability to host ETOX but a greater physical stability, maintaining almost 100 per cent drug solubilized after 28 days. Furthermore, the different structural features of poloxamines and their combination in mixed micelles enabled the tuning of drug release profiles, sustaining the release in the 1–5 days range. These findings together with promising hen's egg test-chorioallantoic membrane biocompatibility tests make poloxamine micelles promising nanocarriers for carbonic anhydrase inhibitors in the treatment of glaucoma. PMID:22491977

  12. Acetazolamide or not, prior to ascent?

    PubMed

    DeLellis, Stephen M

    2010-01-01

    Special Operation Soldiers must be prepared to work in all environmental extremes, frequently with little or no preparation time. While working in extreme heat or cold is uncomfortable, little preparation is necessary as long as reasonably fit Soldiers remain properly nourished, hydrated, or clothed. Working at high altitude poses additional risks that can be pharmacologically mitigated. While new prophylactic therapies are appearing on the scene in mountaineering and high-altitude climbing circles, acetazolamide still appears to be the preferred drug for the prevention of altitude related illness.

  13. Acetazolamide Attenuates Lithium-Induced Nephrogenic Diabetes Insipidus.

    PubMed

    de Groot, Theun; Sinke, Anne P; Kortenoeven, Marleen L A; Alsady, Mohammad; Baumgarten, Ruben; Devuyst, Olivier; Loffing, Johannes; Wetzels, Jack F; Deen, Peter M T

    2016-07-01

    To reduce lithium-induced nephrogenic diabetes insipidus (lithium-NDI), patients with bipolar disorder are treated with thiazide and amiloride, which are thought to induce antidiuresis by a compensatory increase in prourine uptake in proximal tubules. However, thiazides induced antidiuresis and alkalinized the urine in lithium-NDI mice lacking the sodium-chloride cotransporter, suggesting that inhibition of carbonic anhydrases (CAs) confers the beneficial thiazide effect. Therefore, we tested the effect of the CA-specific blocker acetazolamide in lithium-NDI. In collecting duct (mpkCCD) cells, acetazolamide reduced the cellular lithium content and attenuated lithium-induced downregulation of aquaporin-2 through a mechanism different from that of amiloride. Treatment of lithium-NDI mice with acetazolamide or thiazide/amiloride induced similar antidiuresis and increased urine osmolality and aquaporin-2 abundance. Thiazide/amiloride-treated mice showed hyponatremia, hyperkalemia, hypercalcemia, metabolic acidosis, and increased serum lithium concentrations, adverse effects previously observed in patients but not in acetazolamide-treated mice in this study. Furthermore, acetazolamide treatment reduced inulin clearance and cortical expression of sodium/hydrogen exchanger 3 and attenuated the increased expression of urinary PGE2 observed in lithium-NDI mice. These results show that the antidiuresis with acetazolamide was partially caused by a tubular-glomerular feedback response and reduced GFR. The tubular-glomerular feedback response and/or direct effect on collecting duct principal or intercalated cells may underlie the reduced urinary PGE2 levels with acetazolamide, thereby contributing to the attenuation of lithium-NDI. In conclusion, CA activity contributes to lithium-NDI development, and acetazolamide attenuates lithium-NDI development in mice similar to thiazide/amiloride but with fewer adverse effects.

  14. Design of cationic nanostructured heterolipid matrices for ocular delivery of methazolamide

    PubMed Central

    Youshia, John; Kamel, Amany O; El Shamy, Abdelhameed; Mansour, Samar

    2012-01-01

    Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release. This study assessed the feasibility of using nanostructured lipid matrices (NLMs) for ocular delivery of methazolamide-(MZA) adopting heterolipids composed of novel mixtures of Compritol ® and cetostearyl alcohol (CSA), and stabilized by Tween 80®. The systems were prepared using the modified high shear homogenization followed by ultrasonication method, which avoids the use of organic solvents. A 32 full factorial design was constructed to study the influence of two independent variables, namely the ratio of CSA:Compritol and the concentration of Tween 80, each in three levels. The dependent variables were the entrapment efficiency percentages (EE%), mean particle size (PS), polydispersity index (PDI), and zeta potential (ZP). In vivo intraocular pressure (IOP) lowering activity for the selected formulae was compared to that of MZA solution. The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%. The ZP values of all formulae were positive, and greater than 30 mV. The best formula, composed of 4% CSA, 2% Compritol, 0.15% stearylamine, and 2% Tween 80, with EE% of 25.62%, PS of 207.1 nm, PDI of 0.243, and ZP of 41.50 mV, showed in vitro sustained release properties for 8 hours and lowered the intraocular pressure by 8.3 mmHg within 3 hours, with this drop in pressure lasting for 12 hours. PMID:22679362

  15. Hyperphosphatemic familial tumoral calcinosis: response to acetazolamide and postulated mechanisms.

    PubMed

    Finer, Gal; Price, Heather E; Shore, Richard M; White, Kenneth E; Langman, Craig B

    2014-06-01

    Hyperphosphatemic familial tumoral calcinosis (HFTC) is characterized by enhanced renal phosphate absorption, hyperphosphatemia, and tumor-like extraosseous calcifications due to inactivating mutations in FGF23 or associated proteins. Surgical excision is needed when low phosphate diet and phosphate binders are ineffective. Sporadic reports have supported acetazolamide use. We report on a 7-year-old African American boy who presented with severe HFTC requiring numerous surgical excisions. Tumors continued to appear and others reoccurred despite phosphate restriction and sevelamer carbonate. At the age of 9.5 years, acetazolamide (40 mg/kg/day) was added and resulted in mild metabolic acidosis (bicarbonate 25.3 mEq/L vs. 21.4 mEq/L, P < 0.001; serum pH 7.38 vs. 7.31, P = 0.013, pre- and post-acetazolamide, respectively) but no change in tubular reabsorption of phosphate (TRP) (96.9% vs. 95.9%, P = 0.34) or serum phosphate (6.6 mg/dl vs. 6.9 mg/dl, P = 0.52 pre- and post-acetazolamide, respectively). Following the initiation of acetazolamide therapy, the patient experienced significant improvement in disease course as indicated by resolution of localized bone pain, cessation of tumor formation, and no tumor recurrence. Despite mild metabolic acidosis, our patient had improved linear growth and did not develop any other side effects related to therapy. Intact FGF23 remained abnormally low throughout disease course, while C-terminal FGF23 increased with acetazolamide. We conclude that acetazolamide can control severe HFTC by inducing mild metabolic acidosis despite no change in serum phosphate or TRP. This effect may be exerted though improved calcium-phosphate complex solubility and increased FGF23 locally.

  16. Biowaiver monographs for immediate release solid oral dosage forms: acetazolamide.

    PubMed

    Granero, G E; Longhi, M R; Becker, C; Junginger, H E; Kopp, S; Midha, K K; Shah, V P; Stavchansky, S; Dressman, J B; Barends, D M

    2008-09-01

    Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing acetazolamide are reviewed. Acetazolamide's solubility and permeability characteristics according to the Biopharmaceutics Classification System (BCS), as well as its therapeutic use and therapeutic index, its pharmacokinetic properties, data related to the possibility of excipient interactions and reported BE/bioavailability (BA) problems are taken into consideration. The available data on solubility, on oral absorption and permeability are not sufficiently conclusive to classify acetazolamide with certainty. Taking a conservative approach, no biowaiver is considered justified for the registration of new multisource drug products. However, SUPAC level 1 and level 2 postapproval changes and most EU Type I variations can be approved waiving in vivo BE studies.

  17. Acetazolamide in vestibular migraine prophylaxis: a retrospective study.

    PubMed

    Çelebisoy, Neşe; Gökçay, Figen; Karahan, Ceyda; Bilgen, Cem; Kirazlı, Tayfun; Karapolat, Hale; Köse, Timur

    2016-10-01

    The aim of this study is to check the efficacy of acetazolamide in the prophylaxis of vestibular migraine (VM). Treatment options in VM are mainly based on migraine guidelines. We tried to assess the efficacy of acetazolamide in these patients depending on clinical similarities with episodic ataxia type 2 and familial hemiplegic migraine responding to the drug. This is a retrospective cohort study. Among 50 patients with VM and prescribed acetazolamide 500 mg/day, 39 patients were studied as five had been lost on follow-up and six had stopped taking the drug due to side effects. Vertigo and headache frequency determined by number of attacks per month, and the severity determined by visual analog scales measured in centimeters from 0 to 10 were collected from the records. Initial reported figures for frequency and severity were compared with the results gathered after 3 months of treatment. The results were compared. Acetazolamide was effective in reducing both the frequency and severity of vertigo and headache attacks and this effect was more prominent for vertigo frequency and severity.

  18. 21 CFR 520.28 - Acetazolamide sodium soluble powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Acetazolamide sodium soluble powder. 520.28 Section 520.28 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... congestive heart failure and for rapid reduction of intraocular pressure.1 1 These conditions are...

  19. 21 CFR 522.44 - Sterile sodium acetazolamide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sterile sodium acetazolamide. 522.44 Section 522.44 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS §...

  20. 21 CFR 522.44 - Sterile sodium acetazolamide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sterile sodium acetazolamide. 522.44 Section 522.44 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS §...

  1. Acetazolamide for cystoid macular oedema in Bietti crystalline retinal dystrophy.

    PubMed

    Broadhead, Geoffrey K; Chang, Andrew A

    2014-04-01

    Bietti crystalline retinal dystrophy is a rare, inherited disorder whose hallmark is the presence of retinal crystal deposits associated with later chorioretinal degeneration. This condition may rarely be complicated by the development of cystoid macular oedema leading to rapid visual decline. Currently, treatment options for this complication of Bietti dystrophy are limited and the visual prognosis is poor. Here, we present a case of cystoid macular oedema associated with Bietti dystrophy that was successfully diagnosed using multimodal imaging techniques including optical coherence tomography and fluorescein angiography. These modalities confirmed the diagnosis of macular oedema and excluded other possible causes of oedema such as choroidal neovascularisation. In this patient, cystoid macular oedema was resolved with oral acetazolamide therapy, a treatment that has not been previously reported in this context. Acetazolamide treatment resulted in oedema resolution and improvement in visual function, and can be considered a therapeutic option for other patients with Bietti dystrophy who develop cystoid macular oedema.

  2. Carbonic Anhydrase Inhibitors. Part 91. Metal Complexes of Heterocyclic Sulfonamides as Potential Pharmacological Agents in the Treatment of Gastric Acid Secretion Imbalances

    PubMed Central

    Ilies, Marc A.; Scozzafava, Andrea

    2000-01-01

    Zinc, magnesium, aluminum and copper complexes of several potent, clinically used carbonic anhydrase (CA) sulfonamide inhibitors, such as acetazolamide, methazolamide, ethoxzolamide and benzolamide were tested for their possible applications as antacids, in experimental animals. Gastric acid secretion parameters 3 days after treatment with these CA inhibitors (2 × 500 mg, twice a day), in dogs with chronic gastric fistulas, led to the observation that the gastric acid parameters BAO (the basal acid output), and MAO (the maximal acid output after stimulation with histamine) were drastically reduced, as compared to the same parameters in animals that did not receive these enzyme inhibitors. These are promising results for the possible use of metal complexes of heterocyclic sulfonamides as treatment alternatives (alone or in combination with other drugs) for gastric acid secretion imbalances. PMID:18475926

  3. Effects of acetazolamide on cognitive performance during high-altitude exposure.

    PubMed

    Wang, Jiye; Ke, Tao; Zhang, Xiangnan; Chen, Yaoming; Liu, Mingchao; Chen, Jingyuan; Luo, Wenjing

    2013-01-01

    High-altitude hypoxia impedes cognitive performance. It is not well known whether the prophylactic use of acetazolamide for altitude sickness can influence cognitive performance at high altitude. When ascending to high altitude locations, one may face medical risks, including cognitive impairment, which may significantly hinder climbing abilities or exploratory behavior. Effective prophylactic drugs have rarely been reported. Because acetazolamide is commonly used to treat acute mountain sickness (AMS), we assessed the potential effects of acetazolamide on cognitive performance during high-altitude exposure. Twenty-one volunteers aged 22-26 years were randomized to receive a 4-day treatment of acetazolamide (125 mg Bid, n=11) or placebo (n=10) before and after air travel from Xianyang (402 m) to Lhasa (3561 m). Neuropsychological performance was assessed using the digit symbol substitution test (DSST), paced auditory serial addition test (PASAT), operation span task, and free recall test at 6, 30, and 54 h after arrival at Lhasa. The Lake Louise Score (LLS) was used to diagnose AMS. At high altitude, acetazolamide impaired rather than improved neuropsychological measures of concentration, cognitive processing speed, reaction time, short-term memory, and working memory, which were assessed by DSST, PASAT, and operation span task at 6 and 30 h after arrival (p<0.05). However, the prophylactic use of acetazolamide was found to reduce the incidence of AMS compared to the placebo (p<0.05). In conclusion, acetazolamide impairs neuropsychological function, at least in part, shortly after the ascent to high altitude.

  4. Low-Dose Acetazolamide in the Treatment of Premenstrual Dysphoric Disorder: A Case Series

    PubMed Central

    Kotzalidis, Georgios D.; Panaccione, Isabella; Simonetti, Alessio; De Chiara, Lavinia; Del Casale, Antonio; Ambrosi, Elisa; Napoletano, Flavia; Janiri, Delfina; Danese, Emanuela; Girardi, Nicoletta; Rapinesi, Chiara; Serata, Daniele; Manfredi, Giovanni; Koukopoulos, Alexia E.; Angeletti, Gloria; Nicoletti, Ferdinando; Girardi, Paolo

    2014-01-01

    The treatment of premenstrual dysphoric disorder (PMDD) is far from satisfactory, as there is a high proportion of patients who do not respond to conventional treatment. The antidiuretic sulfonamide, acetazolamide, inhibits carbonic anhydrase and potentiates GABAergic transmission; the latter is putatively involved in PMDD. We therefore tried acetazolamide in a series of women with intractable PMDD. Here, we describe a series of eight women diagnosed with DSM-IV-TR PMDD, five of whom had comorbidity with a mood disorder and one with an anxiety disorder, who were resistant to treatment and responded with symptom disappearance after being added-on 125 mg/day acetazolamide for 7-10 days prior to menses each month. Patients were free from premenstrual symptoms at the 12-month follow-up. We suggest that acetazolamide may be used to improve symptoms of PMDD in cases not responding to other treatments. GABAergic mechanisms may be involved in counteracting PMDD symptoms. PMID:24605130

  5. Effect of Acetazolamide on Obesity-Induced Glomerular Hyperfiltration: A Randomized Controlled Trial

    PubMed Central

    Erman, Arie; Bar Sheshet Itach, Sarit; Ori, Yaacov; Rozen-Zvi, Benaya; Gafter, Uzi; Chagnac, Avry

    2015-01-01

    Aims Obesity is an important risk factor for the development of chronic kidney disease. One of the major factors involved in the pathogenesis of obesity-associated kidney disease is glomerular hyperfiltration. Increasing salt-delivery to the macula densa is expected to decrease glomerular filtration rate (GFR) by activating tubuloglomerular feedback. Acetazolamide, a carbonic anhydrase inhibitor which inhibits salt reabsorption in the proximal tubule, increases distal salt delivery. Its effects on obesity-related glomerular hyperfiltration have not previously been studied. The aim of this investigation was to evaluate whether administration of acetazolamide to obese non diabetic subjects reduces glomerular hyperfiltration. Materials and Methods The study was performed using a randomized double-blind crossover design. Obese non-diabetic men with glomerular hyperfiltration were randomized to receive intravenously either acetazolamide or furosemide at equipotent doses. Twelve subjects received the allocated medications. Two weeks later, the same subjects received the drug which they had not received during the first study. Inulin clearance, p-aminohippuric acid clearance and fractional lithium excretion were measured before and after medications administration. The primary end point was a decrease in GFR, measured as inulin clearance. Results GFR decreased by 21% following acetazolamide and did not decrease following furosemide. Renal vascular resistance increased by 12% following acetazolamide, while it remained unchanged following furosemide administration. Natriuresis increased similarly following acetazolamide and furosemide administration. Sodium balance was similar in both groups. Conclusions Intravenous acetazolamide decreased GFR in obese non-diabetic men with glomerular hyperfiltration. Furosemide, administered at equipotent dose, did not affect GFR, suggesting that acetazolamide reduced glomerular hyperfiltration by activating tubuloglomerular feedback

  6. A randomized trial of dexamethasone and acetazolamide for acute mountain sickness prophylaxis.

    PubMed

    Ellsworth, A J; Larson, E B; Strickland, D

    1987-12-01

    Forty-seven climbers participated in a double-blind, randomized trial comparing acetazolamide 250 mg, dexamethasone 4 mg, and placebo every eight hours as prophylaxis for acute mountain sickness during rapid, active ascent of Mount Rainier (elevation 4,392 m). Forty-two subjects (89.4 percent) achieved the summit in an average of 34.5 hours after leaving sea level. At the summit or high point attained above base camp, the group taking dexamethasone reported less headache, tiredness, dizziness, nausea, clumsiness, and a greater sense of feeling refreshed (p less than or equal to 0.05). In addition, they reported fewer problems of runny nose and feeling cold, symptoms unrelated to acute mountain sickness. The acetazolamide group differed significantly (p less than or equal to 0.05) from other groups at low elevations (1,300 to 1,600 m), in that they experienced more feelings of nausea and tiredness, and they were less refreshed. These drug side effects probably obscured the previously established prophylactic effects of acetazolamide for acute mountain sickness. Separate analysis of an acetazolamide subgroup that did not experience side effects at low elevations revealed a prophylactic effect of acetazolamide similar in magnitude to the dexamethasone effect but lacking the euphoric effects of dexamethasone. This study demonstrates that prophylaxis with dexamethasone can reduce the symptoms associated with acute mountain sickness during active ascent and that acetazolamide can cause side effects that may limit its effectiveness as prophylaxis against the disease.

  7. Novel Polymeric Nanoparticles Intended for Ophthalmic Administration of Acetazolamide.

    PubMed

    Quinteros, Daniela A; Ferreira, Luana M; Schaffazick, Scheila Rezende; Palma, Santiago D; Allemandi, Daniel A; Cruz, Letícia

    2016-10-01

    Glaucoma is characterized by increased intraocular pressure (IOP) that results in blindness if it remains untreated. Acetazolamide (AZM) is a carbonic anhydrase inhibitor, mainly used to reduce IOP in the treatment of glaucoma. However, the potential of topical treatment is limited, due to its low permeability across the ocular epithelium. An alternative to overcome this limitation is the incorporation of AZM in nanoparticulate systems, such as polymeric nanocapsules (NCs). In this way, the aim of this work was to prepare and characterize NC formulations containing AZM, using ethylcellulose (EC) and Eudragit(®) RS100 (EUD) as encapsulating polymers. The formulations showed high encapsulation efficiency. Particle size measurements showed that NCs are in the nanometric range. Comparing both groups of formulations, the NCEC proved to be smaller than those prepared with EUD. The formulations prepared with EC showed negative zeta potentials, while NCs of EUD were positively charged. For both groups of formulations, no more than 30% of drug was released in 120 min. Ex vivo and in vivo studies evidenced that the NCEC formulations were the most efficient, because an increased amount of permeated drug was observed, along with a greater IOP decrease and longer duration of the effect in normotensive rabbits.

  8. Acetazolamide lowers intracranial pressure and modulates the cerebrospinal fluid secretion pathway in healthy rats.

    PubMed

    Uldall, Maria; Botfield, Hannah; Jansen-Olesen, Inger; Sinclair, Alexandra; Jensen, Rigmor

    2017-04-03

    Acetazolamide is one of the most widely used drugs for lowering intracranial pressure (ICP) and is believed to reduce cerebrospinal fluid (CSF) secretion via its action on the choroid plexus (CP). In the CP the main driving force for CSF secretion is primarily active transport of Na(+) ions facilitated by the Na/K ATPase. Transmembrane water channels, known as aquaporins (AQP), are also present in the CP and play an important role in the movement of water. In the present study, we investigated the effect of a single dose acetazolamide on the activity of the Na/K ATPase and ICP. Furthermore, we investigated the expression of Na/K ATPase, AQP1 and AQP4 in the CP tissue following acetazolamide treatment. 12 female Sprague Dawley rats were randomized into two groups; one group received 200mg acetazolamide and the other vehicle treatment. All animals were subjected to ICP recordings and the CP tissue was collected for qPCR and western blot analysis. The effect of acetazolamide on the Na/K ATPase activity was evaluated in an in vitro assay of primary CP epithelial cells isolated from rats. Acetazolamide significantly lowered ICP within 10min of injection compared to the vehicle group (P<0.05), reaching a maximum reduction at 55min 66±4% (P<0.00001). Acetazolamide also significantly decreased the activity of the Na/K ATPase in CP epithelial cells compared to vehicle (P=0.0022). Acetazolamide did not change the AQP1, AQP4 or Na/K ATPase mRNA content in the CP tissue. However, we did record an increase in the amount of AQP1 (p=0.0152) and Na/K ATPase (p=0.0411) protein in the membrane fraction of the CP, but not AQP4 (p=0.0649). A single dose of acetazolamide lowers ICP and modulates the CSF secretion pathway in healthy rats - Firstly, by inhibiting the Na/K ATPase to slow the CSF production, secondly, by increasing AQP1 and Na/K ATPase protein in the membrane of the CP epithelial cells.

  9. Possible association between acetazolamide administration during pregnancy and multiple congenital malformations

    PubMed Central

    Al-Saleem, Afnan I; Al-Jobair, Asma M

    2016-01-01

    Congenital malformations might occur because of environmental or genetic factors, and sometimes occur because of unknown causes. Acetazolamide is a carbonic anhydrase inhibitor that is used to treat idiopathic intracranial hypertension, glaucoma, and epilepsy. The use of acetazolamide has not been recommended for pregnant women because of reported teratogenic risks. Congenital malformations, such as ectrodactyly, syndactyly, cleft lip/palate, and retarded incisor teeth development, have been reported in experimental animals. However, tooth agenesis due to the use of acetazolamide has not been reported yet. Oligodontia is a severe type of tooth agenesis involving six or more congenitally missing teeth. The causes of oligodontia are attributed to environmental factors, such as irradiation, drugs, trauma, tumors, infection, genetic factors, or a combination. There is no credible evidence of undesirable effects of acetazolamide use in human pregnancy. However, we report a case of a 12-year-old Saudi boy who was exposed to maternal acetazolamide (1,000 mg/day) for treatment of idiopathic intracranial hypertension before pregnancy, during the first trimester, and throughout the pregnancy. This treatment might have resulted in some congenital malformations, such as ectrodactyly, syndactyly, and oligodontia. PMID:27143854

  10. Acetazolamide challenge for three-dimensional time-of-flight MR angiography of the brain

    SciTech Connect

    Mandai, Kenji; Sueyoshi, Kenji; Fukunaga, Ryuzo; Nukada, Masaru; Ohtani, Fumio; Araki, Yutaka; Tsukaguchi, Isao; Abe, Hiroshi )

    1994-04-01

    We compared three-dimensional time-of-flight MR angiograms obtained before and after acetazolamide administration to evaluate whether use of this drug could improve visualization of small peripheral intracranial arteries and atherosclerotic stenosis. For evaluation of small peripheral arteries, 10 patients with clinical diagnosis of ischemic cerebrovascular disease and 10 healthy volunteers were investigated, and for evaluation of stenosis, another 6 patients were investigated. Vascular images were obtained by three-dimensional time-of-flight MR angiography. After a baseline scan, 17 mg/kg acetazolamide was injected intravenously and the second scan was performed 20 minutes later. Several small peripheral arteries that had not been seen on the baseline images were visible on the acetazolamide images without any augmentation of the background signals. Stenotic lesions in the main trunks of the major cerebral arteries were detected more clearly on acetazolamide images. Acetazolamide improves visualization of small peripheral intracranial arteries and sensitivity in detecting atherosclerotic stenosis in the main trunk of major cerebral artery by three-dimensional time-of-flight MR angiography without changing MR apparatus and software. 15 refs., 5 figs., 2 tabs.

  11. Mapping of the cerebral response to acetazolamide using graded asymmetric spin echo EPI.

    PubMed

    Mukherjee, Bhashkar; Preece, Mark; Houston, Gavin C; Papadakis, Nikolas G; Carpenter, T Adrian; Hall, Laurance D; Huang, Christopher L-H

    2005-11-01

    Cerebral vascular reactivity in different regions of the rat brain was quantitatively characterized by spatial and temporal measurements of blood oxygenation level-dependent (BOLD)-fMRI signals following intravenous administration of the carbonic anhydrase inhibitor acetazolamide: this causes cerebral vasodilatation through a cerebral extracellular acidosis that spares neuronal metabolism and vascular smooth muscle function, thus separating vascular and cerebral metabolic events. An asymmetric spin echo-echo planar imaging (ASE-EPI) pulse sequence sensitised images selectively to oxygenation changes in the microvasculature; use of a surface coil receiver enhanced image signal-to-noise ratios (SNRs). Image SNRs and hardware integrity were verified by incorporating quality assurance procedures; cardiorespiratory stability in the physiological preparations were monitored and maintained through the duration of the experiments. These conditions made it possible to apply BOLD contrast fMRI to map regional changes in cerebral perfusion in response to acetazolamide administration. Thus, fMRI findings demonstrated cerebral responses to acetazolamide that directly paralleled the known physiological actions of acetazolamide and whose time courses were similar through all regions of interest, consistent with acetazolamide's initial distribution in brain plasma, where it affects cerebral haemodynamics by acting at cerebral capillary endothelial cells. However, marked variations in the magnitude of the responses suggested relative perfusion deficits in the hippocampus and white matter regions correlating well with their relatively low vascularity and the known vulnerability of the hippocampus to ischaemic damage.

  12. Impaired cerebral vasoreactivity after embolization of arteriovenous malformations: assessment with serial acetazolamide challenge xenon CT

    SciTech Connect

    Tarr, R.W.; Johnson, D.W.; Horton, J.A.; Yonas, H.; Pentheny, S.; Durham, S.; Jungreis, C.A.; Hecht, S.T. )

    1991-05-01

    Embolization of a portion of the nidus of an arteriovenous malformation not only may alter hemodynamics within the nidus, but also may change blood flow dynamics in adjacent normal vessels. Sequential acetazolamide-challenge xenon CT cerebral blood flow studies were performed in eight patients before and after embolization of arteriovenous malformations to assess the hemodynamic effects on the major vascular territories supplying the malformation. Acetazolamide is a potent cerebral vasodilator, and its administration combined with cerebral blood flow studies allows assessment of cerebral vasoreactivity. In seven of the eight patients, one or more parenchymal areas exhibited a normal cerebral blood flow augmentation response to acetazolamide before embolization, but diminished acetazolamide flow augmentation was seen after embolization, indicating abnormal vasoreactivity. We found that the decrease in vasoreactivity peaked 6-10 days after embolization. In one of the eight patients, a temporary delayed neurologic deficit developed during a period of impaired cerebral vasoreactivity following embolization. Our results suggest that embolization of an arteriovenous malformation can induce vasoreactivity changes in adjacent normal vessels. Because these changes appear to be somewhat time-dependent, an appropriate interval should be observed between embolization stages or before surgical resection of an arteriovenous malformation following embolization to allow hemodynamic equilibration to occur. Acetazolamide challenge combined with serial cerebral blood flow studies following embolization enables determination of this hemodynamic equilibration.

  13. Impact of Acetazolamide and CPAP on Cortical Activity in Obstructive Sleep Apnea Patients

    PubMed Central

    Stadelmann, Katrin; Latshang, Tsogyal D.; Nussbaumer-Ochsner, Yvonne; Tarokh, Leila; Ulrich, Silvia; Kohler, Malcolm; Bloch, Konrad E.; Achermann, Peter

    2014-01-01

    Study Objectives 1) To investigate the impact of acetazolamide, a drug commonly prescribed for altitude sickness, on cortical oscillations in patients with obstructive sleep apnea syndrome (OSAS). 2) To examine alterations in the sleep EEG after short-term discontinuation of continuous positive airway pressure (CPAP) therapy. Design Data from two double-blind, placebo-controlled randomized cross-over design studies were analyzed. Setting Polysomnographic recordings in sleep laboratory at 490 m and at moderate altitudes in the Swiss Alps: 1630 or 1860 m and 2590 m. Patients Study 1: 39 OSAS patients. Study 2: 41 OSAS patients. Interventions Study 1: OSAS patients withdrawn from treatment with CPAP. Study 2: OSAS patients treated with autoCPAP. Treatment with acetazolamide (500–750 mg) or placebo at moderate altitudes. Measurements and Results An evening dose of 500 mg acetazolamide reduced slow-wave activity (SWA; approximately 10%) and increased spindle activity (approximately 10%) during non-REM sleep. In addition, alpha activity during wake after lights out was increased. An evening dose of 250 mg did not affect these cortical oscillations. Discontinuation of CPAP therapy revealed a reduction in SWA (5–10%) and increase in beta activity (approximately 25%). Conclusions The higher evening dose of 500 mg acetazolamide showed the “spectral fingerprint” of Benzodiazepines, while 250 mg acetazolamide had no impact on cortical oscillations. However, both doses had beneficial effects on oxygen saturation and sleep quality. PMID:24710341

  14. Sulfonamide inhibition studies of the β-carbonic anhydrase from the newly discovered bacterium Enterobacter sp. B13.

    PubMed

    Eminoğlu, Ayşenur; Vullo, Daniela; Aşık, Aycan; Çolak, Dilşat Nigar; Çanakçı, Sabriye; Beldüz, Ali Osman; Supuran, Claudiu T

    2016-04-01

    The genome of the newly identified bacterium Enterobacter sp. B13 encodes for a β-class carbonic anhydrases (CAs, EC 4.2.1.1), EspCA. This enzyme was recently cloned, and characterized kinetically by this group (J. Enzyme Inhib. Med. Chem. 2016, 31). Here we report an inhibition study with sulfonamides and sulfamates of this enzyme. The best EspCA inhibitors were some sulfanylated sulfonamides with elongated molecules, metanilamide, 4-aminoalkyl-benzenesulfonamides, acetazolamide, and deacetylated methazolamide (KIs in the range of 58.7-96.5nM). Clinically used agents such as methazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide, zonisamide, sulthiame, sulpiride, topiramate and valdecoxib were slightly less effective inhibitors (KIs in the range of 103-138nM). Saccharin, celecoxib, dichlorophenamide and many simple benzenesulfonamides were even less effective as EspCA inhibitors, with KIs in the range of 384-938nM. Identification of effective inhibitors of this bacterial enzyme may lead to pharmacological tools useful for understanding the physiological role(s) of the β-class CAs in bacterial pathogenicity/virulence.

  15. Effect of Acetazolamide on Visual Function in Patients With Idiopathic Intracranial Hypertension and Mild Visual Loss

    PubMed Central

    2015-01-01

    IMPORTANCE Acetazolamide is commonly used to treat idiopathic intracranial hypertension (IIH), but there is insufficient information to establish an evidence base for its use. OBJECTIVE To determine whether acetazolamide is beneficial in improving vision when added to a low-sodium weight reduction diet in patients with IIH and mild visual loss. DESIGN, SETTING, AND PARTICIPANTS Multicenter, randomized, double-masked, placebo-controlled study of acetazolamide in 165 participants with IIH and mild visual loss who received a low-sodium weight-reduction diet. Participants were enrolled at 38 academic and private practice sites in North America from March 2010 to November 2012 and followed up for 6 months (last visit in June 2013). All participants met the modified Dandy criteria for IIH and had a perimetric mean deviation (PMD) between −2 dB and −7 dB. The mean age was 29 years and all but 4 participants were women. INTERVENTIONS Low-sodium weight-reduction diet plus the maximally tolerated dosage or acetazolamide (up to 4 g/d) or matching placebo for 6 months. MAIN OUTCOMES AND MEASURES The planned primary outcome variable was the change in PMD from baseline to month 6 in the most affected eye, as measured by Humphrey Field Analyzer. Perimetric mean deviation is a measure of global visual field loss (mean deviation from age-corrected normal values), with a range of 2 to −32 dB; larger negative values indicate greater vision loss. Secondary outcome variables included changes in papilledema grade, quality of life (Visual Function Questionnaire 25 [VFQ-25] and 36-Item Short Form Health Survey), headache disability, and weight at month 6. RESULTS The mean improvement in PMD was greater with acetazolamide (1.43 dB, from −3.53 dB at baseline to −2.10 dB at month 6; n = 86) than with placebo (0.71 dB, from −3.53 dB to −2.82 dB;n = 79); the difference was 0.71 dB (95% CI, 0 to 1.43 dB; P= .050). Mean improvements in papilledema grade (acetazolamide: −1

  16. Acetazolamide and ADH, Renin, Aldosterone, and Water Electrolytes at 4100 M in Man,

    DTIC Science & Technology

    1986-05-01

    diuresis , natriuresis , and kaliuresis on day 1,, DD IAN 1473 EDT~orW oF NOV 611IS OBSOLETE JAM UNCLASSIFIED ~6 .6 / 3 o,5’/ SECURITY CLASSIFICATION OF...grntp Imnd showed no response to HA (Table 3). Acetazolamide resulted in a diuresis (P 0.,1) on the fir-t d,v . concurrently reduced sensible water

  17. Effects of acetazolamide on cerebral blood flow and brain tissue oxygenation.

    PubMed Central

    Lassen, N. A.; Friberg, L.; Kastrup, J.; Rizzi, D.; Jensen, J. J.

    1987-01-01

    Oral administration of 1 g of acetazolamide to 8 normal subjects studied at sea level and in normoxia caused an acute increase in cerebral blood flow (CBF). During the subsequent prolonged oral treatment with 1 g of acetazolamide daily, CBF returned to normal within 2 days. The alveolar CO2 tension decreased gradually to 70% of the control value, indicating hyperventilation. At sea level hyperventilation will not increase brain oxygenation significantly in normal man, as the arterial oxygen content only increases minimally, while CBF is unchanged. At high altitude the beneficial effects of acetazolamide on the symptoms of acute mountain sickness may well be due to an improved oxygen supply to the brain, as hyperventilation will, at the low ambient PO2, cause a significant increase of the arterial oxygen content, while CBF presumably is unaffected by the drug. During hypoxia at high altitude the overall effect of prolonged acetazolamide treatment may thus be equivalent to a descent by several hundred metres. PMID:3118350

  18. Role of carbonic anhydrase in bone - Partial inhibition of disuse atrophy of bone by parenteral acetazolamide

    NASA Technical Reports Server (NTRS)

    Kenny, A. D.

    1985-01-01

    The effectiveness of orally and subcutaneously administered acetazolamide sodium in preventing denervation-induced bone loss in rats is examined. Male Sprague-Dawley rats were treated with acetazolamide either orally by incorporation of 0.2, 0.5, or 1.5 percent concentrations in their diet for 15 days, or subcutaneously by either injection of 0.5 ml/rat of a solution containing either 20 or 100 mg/ml of the drug twice daily for 15 days or by continuous infusion of 5, 50, 500, or 1000 mg/ml of acetazolamide sodium for 8 days using an osmotic minipump. The effects of acetazolamide on body weight, food consumption, and plasma calcium content are evaluated. It is observed that parenteral administration is equally effective as oral administration in partially preventing denervation-induced bone mass changes. The data reveal that approximately 50 percent protection occurs with daily doses of 1094, 129, and 8 mg/kg body weight for the oral, subcutaneous injection, and subcutaneous infusion methods, respectively.

  19. Identifying the lowest effective dose of acetazolamide for the prophylaxis of acute mountain sickness: systematic review and meta-analysis

    PubMed Central

    Low, Emma V; Gupta, Vaibhav; Schedlbauer, Angela; Grocott, Michael P W

    2012-01-01

    Objectives To assess the efficacy of three different daily doses of acetazolamide in the prevention of acute mountain sickness and to determine the lowest effective dose. Design Systematic review and meta-analysis. Data sources Medline and Embase along with a hand search of selected bibliographies. No language restrictions were applied. Study selection Randomised controlled trials assessing the use of acetazolamide at 250 mg, 500 mg, or 750 mg daily versus placebo in adults as a drug intervention for the prophylaxis of acute mountain sickness. Included studies were required to state the administered dose of acetazolamide and to randomise participants before ascent to either acetazolamide or placebo. Two reviewers independently carried out the selection process. Data extraction Two reviewers extracted data concerning study methods, pharmacological intervention with acetazolamide, method of assessment of acute mountain sickness, and event rates in both control and intervention groups, which were verified and analysed by the review team collaboratively. Data synthesis 11 studies (with 12 interventions arms) were included in the review. Acetazolamide at doses of 250 mg, 500 mg, and 750 mg were all effective in preventing acute mountain sickness above 3000 m, with a combined odds ratio of 0.36 (95% confidence interval 0.28 to 0.46). At a dose of 250 mg daily the number needed to treat for acetazolamide to prevent acute mountain sickness was 6 (95% confidence interval 5 to 11). Heterogeneity ranged from I2=0% (500 mg subgroup) to I2=44% (750 mg subgroup). Conclusions Acetazolamide in doses of 250 mg, 500 mg, and 750 mg daily are all more effective than placebo for preventing acute mountain sickness. Acetazolamide 250 mg daily is the lowest effective dose to prevent acute mountain sickness for which evidence is available. PMID:23081689

  20. Acetazolamide or dexamethasone use versus placebo to prevent acute mountain sickness on Mount Rainier.

    PubMed

    Ellsworth, A J; Meyer, E F; Larson, E B

    1991-03-01

    Eighteen climbers actively ascended Mount Rainier (elevation 4,392 m) twice during a randomized, double-blind, concurrent, placebo-controlled, crossover trial comparing the use of acetazolamide, 250 mg, dexamethasone, 4 mg, and placebo every 8 hours as prophylaxis for acute mountain sickness. Each subject was randomly assigned to receive placebo during one ascent and one of the active medications during the other ascent. Assessment of acute mountain sickness was performed using the Environmental Symptoms Questionnaire and a clinical interview. At the summit or high point attained above base camp, the use of dexamethasone significantly reduced the incidence of acute mountain sickness and the severity of symptoms. Cerebral and respiratory symptom severity scores for subjects receiving dexamethasone (0.26 +/- 0.16 and 0.20 +/- 0.19, respectively) were significantly lower than similar scores for both acetazolamide (0.80 +/- 0.80 and 1.20 +/- 1.05; P = 0.25) and placebo (1.11 +/- 1.02 and 1.45 +/- 1.27; P = .025). Neither the use of dexamethasone nor that of acetazolamide measurably affected other physical or mental aspects. Compared with placebo, dexamethasone appears to be effective for prophylaxis of symptoms associated with acute mountain sickness accompanying rapid ascent. The precise role of dexamethasone for the prophylaxis of acute mountain sickness is not known, but it can be considered for persons without contraindications who are intolerant of acetazolamide, for whom acetazolamide is ineffective, or who must make forced, rapid ascent to high altitude for a short period of time with a guaranteed retreat route.

  1. Acetazolamide or dexamethasone use versus placebo to prevent acute mountain sickness on Mount Rainier.

    PubMed Central

    Ellsworth, A. J.; Meyer, E. F.; Larson, E. B.

    1991-01-01

    Eighteen climbers actively ascended Mount Rainier (elevation 4,392 m) twice during a randomized, double-blind, concurrent, placebo-controlled, crossover trial comparing the use of acetazolamide, 250 mg, dexamethasone, 4 mg, and placebo every 8 hours as prophylaxis for acute mountain sickness. Each subject was randomly assigned to receive placebo during one ascent and one of the active medications during the other ascent. Assessment of acute mountain sickness was performed using the Environmental Symptoms Questionnaire and a clinical interview. At the summit or high point attained above base camp, the use of dexamethasone significantly reduced the incidence of acute mountain sickness and the severity of symptoms. Cerebral and respiratory symptom severity scores for subjects receiving dexamethasone (0.26 +/- 0.16 and 0.20 +/- 0.19, respectively) were significantly lower than similar scores for both acetazolamide (0.80 +/- 0.80 and 1.20 +/- 1.05; P = 0.25) and placebo (1.11 +/- 1.02 and 1.45 +/- 1.27; P = .025). Neither the use of dexamethasone nor that of acetazolamide measurably affected other physical or mental aspects. Compared with placebo, dexamethasone appears to be effective for prophylaxis of symptoms associated with acute mountain sickness accompanying rapid ascent. The precise role of dexamethasone for the prophylaxis of acute mountain sickness is not known, but it can be considered for persons without contraindications who are intolerant of acetazolamide, for whom acetazolamide is ineffective, or who must make forced, rapid ascent to high altitude for a short period of time with a guaranteed retreat route. PMID:2028586

  2. Quantifying the changes in oxygen extraction fraction and cerebral activity caused by caffeine and acetazolamide.

    PubMed

    Buch, Sagar; Ye, Yongquan; Haacke, E Mark

    2017-03-01

    A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease. We aimed to measure the change in venous oxygen saturation (Yv) before and after the intake of the vaso-dynamic agents caffeine and acetazolamide with high spatial resolution using susceptibility mapping. Caffeine and acetazolamide were administered on separate days to five healthy volunteers to measure the change in oxygen extraction fraction. The internal streaking artifacts in the susceptibility maps were reduced by giving an initial susceptibility value uniformly to the structure-of-interest, based on a priori information. Using this technique, Yv for normal physiological conditions, post-caffeine and post-acetazolamide was measured inside the internal cerebral veins as YNormal = 69.1 ± 3.3%, YCaffeine = 60.5 ± 2.8%, and YAcet = 79.1 ± 4.0%. This suggests that susceptibility mapping can serve as a sensitive biomarker for measuring reductions in cerebro-vascular reserve through abnormal vascular response. The percentage change in oxygen extraction fraction for caffeine and acetazolamide were found to be +27.0 ± 3.8% and -32.6 ± 2.1%, respectively. Similarly, the relative changes in cerebral blood flow in the presence of caffeine and acetazolamide were found to be -30.3% and + 31.5%, suggesting that the cerebral metabolic rate of oxygen remains stable between normal and challenged brain states for healthy subjects.

  3. Acetazolamide serves as selective delivery vehicle for dipeptide-linked drugs to renal cell carcinoma

    PubMed Central

    Cazzamalli, Samuele; Dal Corso, Alberto; Neri, Dario

    2016-01-01

    In most cases, cytotoxic drugs do not preferentially accumulate at the tumor site, causing unwanted toxicities and preventing dose escalation to therapeutically active regimens. Here, we show that acetazolamide derivatives, which bind to carbonic anhydrase IX (CAIX) on the surface of kidney cancer cells, selectively deliver payloads at the site of disease, sparing normal organs. Biodistribution studies, performed in tumor-bearing mice with acetazolamide derivatives bearing a technetium-99m chelator complex or a red fluorophore as payload, revealed a preferential tumor accumulation of the compound at doses up to 560 nmol/Kg. The percentage of injected dose per gram in the tumor was dose-dependent and revealed optimal tumor:organ ratios at 140 nmol/Kg, with a tumor:blood ratio of 80:1 at 6 h. Acetazolamide, coupled to potent cytotoxic drugs via a dipeptide linker, exhibited a potent antitumor activity in nude mice bearing SKRC-52 renal cell carcinomas, while drug derivatives devoid of the acetazolamide moiety did not exhibit any detectable anticancer activity at the same doses. The observation of tumor regression with a noninternalizing ligand and with different cytotoxic moieties (MMAE and PNU-159682) indicates a general mechanism of action, based on the selective accumulation of the product on tumor cells, followed by the extracellular proteolytic release of the cytotoxic payload at the neoplastic site and the subsequent drug internalization into tumor cells. Acetazolamide-based drug conjugates may represent a promising class of targeted agents for the treatment of metastatic kidney cancer, as the majority of human clear cell renal cell carcinomas are strongly positive for CAIX. PMID:27609641

  4. Methazolamide-loaded solid lipid nanoparticles modified with low-molecular weight chitosan for the treatment of glaucoma: vitro and vivo study.

    PubMed

    Wang, Fengzhen; Chen, Li; Zhang, Dongsheng; Jiang, Sunmin; Shi, Kun; Huang, Yuan; Li, Rui; Xu, Qunwei

    2014-11-01

    The aims of this study were to design and characterize methazolamide (MTZ)-loaded solid lipid nanoparticles (SLN) with and without modification of low molecular weight chitosan (CS) and compare their potentials for ocular drug delivery. Low molecular weight CS was obtained via a modified chemical oxidative degradation method. SLN with CS (CS-SLN-MTZ) and without CS (SLN-MTZ) were prepared according to a modified emulsion-solvent evaporation method. SLN-MTZ and CS-SLN-MTZ were 199.4 ± 2.8 nm and 252.8 ± 4.0 nm in particle size, -21.3 ± 1.9 mV and +31.3 ± 1.7 mV in zeta potential, respectively. Physical stability studies demonstrated that CS-SLN-MTZ remained stable for at least 4 months at 4 °C, while SLN-MTZ no more than 2 months. A prolonged in vitro release profile of MTZ from CS-SLN-MTZ was obtained compared with SLN-MTZ. Furthermore, CS-SLN-MTZ presented a better permeation property in excised rabbit cornea. In vivo studies indicated that the intraocular pressure lowering effect of CS-SLN-MTZ (245.75 ± 18.31 mmHg × h) was significantly better than both SLN-MTZ (126.74 ± 17.73 mmHg × h) and commercial product Brinzolamide Eye Drops AZOPT® (171.17 ± 16.45 mmHg × h). The maximum percentage decrease in IOP of CS-SLN-MTZ (42.78 ± 7.71%) was higher than SLN-MTZ (27.82 ± 4.15%) and was comparable to AZOPT (38.06 ± 1.25%). CS-SLN-MTZ showed no sign of ocular irritancy according to the Draize method and the histological examination.

  5. Binary and ternary cocrystals of sulfa drug acetazolamide with pyridine carboxamides and cyclic amides.

    PubMed

    Bolla, Geetha; Nangia, Ashwini

    2016-03-01

    A novel design strategy for cocrystals of a sulfonamide drug with pyridine carboxamides and cyclic amides is developed based on synthon identification as well as size and shape match of coformers. Binary adducts of acetazolamide (ACZ) with lactams (valerolactam and caprolactam, VLM, CPR), cyclic amides (2-pyridone, labeled as 2HP and its derivatives MeHP, OMeHP) and pyridine amides (nicotinamide and picolinamide, NAM, PAM) were obtained by manual grinding, and their single crystals by solution crystallization. The heterosynthons in the binary cocrystals of ACZ with these coformers suggested a ternary combination for ACZ with pyridone and nicotinamide. Novel supramolecular synthons of ACZ with lactams and pyridine carboxamides are reported together with binary and ternary cocrystals for a sulfonamide drug. This crystal engineering study resulted in the first ternary cocrystal of acetazolamide with amide coformers, ACZ-NAM-2HP (1:1:1).

  6. Binary and ternary cocrystals of sulfa drug acetazolamide with pyridine carboxamides and cyclic amides

    PubMed Central

    Bolla, Geetha; Nangia, Ashwini

    2016-01-01

    A novel design strategy for cocrystals of a sulfonamide drug with pyridine carboxamides and cyclic amides is developed based on synthon identification as well as size and shape match of coformers. Binary adducts of acetazolamide (ACZ) with lactams (valerolactam and caprolactam, VLM, CPR), cyclic amides (2-pyridone, labeled as 2HP and its derivatives MeHP, OMeHP) and pyridine amides (nicotinamide and picolinamide, NAM, PAM) were obtained by manual grinding, and their single crystals by solution crystallization. The heterosynthons in the binary cocrystals of ACZ with these coformers suggested a ternary combination for ACZ with pyridone and nicotinamide. Novel supramolecular synthons of ACZ with lactams and pyridine carboxamides are reported together with binary and ternary cocrystals for a sulfonamide drug. This crystal engineering study resulted in the first ternary cocrystal of acetazolamide with amide coformers, ACZ–NAM–2HP (1:1:1). PMID:27006778

  7. Successful treatment of central retinal artery thromboembolism with ocular massage and intravenous acetazolamide.

    PubMed

    Duxbury, Oliver; Bhogal, Pervinder; Cloud, Geoffrey; Madigan, Jeremy

    2014-12-05

    A 67-year-old woman presented with left-sided headache and blurred vision, worse during hypertensive episodes. CT angiography showed a 4 mm left internal carotid artery (ICA) aneurysm incorporating the ophthalmic artery. She passed a test balloon occlusion, so the aneurysm was coil occluded, without immediate complication. Four days postprocedure she experienced sudden loss of vision in the left eye and funduscopy showed central retinal artery occlusion secondary to emboli from the coiled aneurysm. She was treated promptly with intravenous acetazolamide and ocular massage and regained full visual acuity. Thromboembolism to the eye during or after neurointerventional treatment is a relatively rare but devastating complication. This report demonstrates the effectiveness of combined intravenous acetazolamide and ocular massage in dealing with this complication when delivered promptly.

  8. Spinocerebellar ataxia type 6 with positional vertigo and acetazolamide responsive episodic ataxia

    PubMed Central

    Jen, J.; Yue, Q.; Karrim, J.; Nelson, S.; Baloh, R.

    1998-01-01

    The SCA6 mutation, a small expansion of a CAG repeat in a calcium channel gene CACNA1A, was identified in three pedigrees. Point mutations in other parts of the gene CACNA1A were excluded and new clinical features of SCA6 reported—namely, central positional nystagmus and episodic ataxia responsive to acetazolamide. The three allelic disorders, episodic ataxia type 2, familial hemiplegic migraine, and SCA6, have overlapping clinical features.

 PMID:9771787

  9. Acute Mountain Sickness Symptom Severity at the South Pole: The Influence of Self-Selected Prophylaxis with Acetazolamide

    PubMed Central

    Johnson, Jacob B.; Richert, Maile; Miller, Andrew D.

    2016-01-01

    Introduction Acetazolamide, a carbonic anhydrase inhibitor, remains the only FDA approved pharmaceutical prophylaxis for acute mountain sickness (AMS) though its effectiveness after rapid transport in real world conditions is less clear. Methods Over 2 years, 248 healthy adults traveled by airplane from sea level (SL) to the South Pole (ALT, ~3200m) and 226 participants provided Lake Louise Symptom Scores (LLSS) on a daily basis for 1 week; vital signs, blood samples, and urine samples were collected at SL and at ALT. Acetazolamide was available to any participant desiring prophylaxis. Comparisons were made between the acetazolamide with AMS (ACZ/AMS) (n = 42), acetazolamide without AMS (ACZ/No AMS)(n = 49), no acetazolamide with AMS (No ACZ/AMS) (n = 56), and the no acetazolamide without AMS (No ACZ/No AMS) (n = 79) groups. Statistical analysis included Chi-squared and one-way ANOVA with Bonferroni post-hoc tests. Significance was p≤0.05. Results No significant differences were found for between-group characteristics or incidence of AMS between ACZ and No ACZ groups. ACZ/AMS reported greater LLSS, BMI, and red cell distribution width. ACZ/No AMS had the highest oxygen saturation (O2Sat) at ALT. No significant differences were found in serum electrolyte concentrations or PFT results. Discussion Acetazolamide during rapid ascent provided no apparent protection from AMS based on LLSS. However, it is unclear if this lack of effect was directly associated with the drug or if perhaps there was some selection bias with individuals taking ACZ more likely to have symptoms or if there may have been more of perceptual phenomenon related to a constellation of side effects. PMID:26848757

  10. Effects of Acetazolamide on the Unrinary Excretion of Cyclic AMP and on the Activity of Renal Adenyl Cyclase

    PubMed Central

    Rodriguez, Hector J.; Walls, John; Yates, Jesse; Klahr, Saulo

    1974-01-01

    Acetazolamide, an inhibitor of the enzyme carbonic anhydrase, increased the urinary excretion of cyclic AMP in normal and parathyroidectomized rats. The increase was greater in rats with intact parathyroid glands than in parathyroidectomized rats. This rise in the urinary excretion of cyclic AMP was not due to an increase in urine flow or a change in urine pH. Furosemide caused an increase in urine flow, but did not affect the excretion of cyclic AMP or phosphate. Alkalinization of the urine with bicarbonate did not increase the urinary excretion of phosphate or cyclic AMP. Acetazolamide increased the productionof cyclic AMP by rat renal cortical slices in vitro. This effect was dose-dependent. Acetazolamide also stimulated the activity of renal cortical adenyl cyclase in a dose-dependent manner but had no effect on the activity of cyclic nucleotide phosphodiesterase. The pattern of urinary excretion of cyclic AMP and phosphate after administration of acetazolamide was similar to that observed in rats given parathyroid hormone. It is suggested that acetazolamide stimulates the renal production of cyclic AMP by activating adenyl cyclase and that this may be the mechanism by which this inhibitor of carbonic anhydrase produces phosphaturia. PMID:4357608

  11. Acetazolamide on the ventral medulla of the cat increases phrenic output and delays the ventilatory response to CO sub 2

    SciTech Connect

    Coates, E.L.; Aihua Li; Nattie, E.E. )

    1991-03-11

    Acetazolamide applied to the surface of the rostral ventrolateral medulla or microinjected beneath the medullary surface in chloralose-urethan-anesthetized, vagotomized, carotid denervated, paralyzed, servo-ventilated cats produced a long-lasting increase in phrenic minute ventilation. Extracellular pH measured beneath the rostral ventrolateral medulla exhibited a long-lasting decrease after surface acetazolamide but was not a good predictor, in each individual animal, of changes in phrenic activity. Medullary carbonic anhydrase inhibition reduced the slope and the half-time of the phrenic response to rapid step CO{sub 2} increases. Conversely, acetazolamide did not effect the phrenic response to steady state CO{sub 2} increases. These data indicate that localized inhibition of medullary carbonic anhydrase causes a centrally mediated increase in ventilation that the authors attribute to medullary tissue acidosis. In addition, these data indicate that medullary carbonic anhydrase may play a role in central CO{sub 2} chemotransduction.

  12. Comparative study of acetazolamide and spironolactone on body fluid compartments on induction to high altitude

    NASA Astrophysics Data System (ADS)

    Singh, M. V.; Jain, S. C.; Rawal, S. B.; Divekar, H. M.; Parshad, Rajinder; Tyagi, A. K.; Sinha, K. C.

    1986-03-01

    Studies were conducted on 29 male healthy subjects having no previous experience of living at high altitude. These subjects were divided into three groups, i.e., subjects treated with placebo, acetazolamide and spironolactone. These subjects were first studied in Delhi. The drug schedule was started 24 hour prior to the airlift of these subjects to an altitude of 3,500 m and was continued for 48 hour after arrival at high altitude. Total body water, extra cellular water, plasma volume, blood electrolytes, pH, pO2, pCO2 and blood viscosity were determined on 3rd and 12th day of their stay at high altitude. Total body water, extra cellular water intracellular water and plasma volume decreased on high altitude exposure. There was a further slight decrease in these compartments with acetazolamide and spironolactone. It was also observed that spironolactone drives out more water from the extracellular compartment. Loss of plasma water was also confirmed by increased plasma osmolality. Increase in arterial blood pH was noticed on hypoxic exposure but the increase was found less in acetazolamide and spironolactone cases. This decrease in pH is expected to result in better oxygen delivery to the tissues at the low oxygen tension. It was also confirmed because blood pO2 increased in both the groups. No significant change in plasma electrolytes was observed in subjects of various groups. Blood viscosity slightly increased on exposure to high altitude. The degree of rise was found less in the group treated with spironolactone. This study suggests that both the drugs are likely to be beneficial in ameliorating/prevention of AMS syndrome.

  13. CT Perfusion with Acetazolamide Challenge in C6 Gliomas and Angiogenesis

    PubMed Central

    Feng, Xiao-Yuan; Qiang, Jin-Wei; Zhang, Jia-wen; Wang, Yong-gang; Liu, Ying

    2015-01-01

    Background This study was performed to investigate the correlation between CT perfusion with acetazolamide challenge and angiogenesis in C6 gliomas. Methods Thirty-two male Sprague-Dawley rats were evaluated. The rats were divided randomly to four groups: eight rats with orthotopically implanted C6 gliomas at 10-days old (Group A), eight rats with gliomas at 14-days old (Group B), eight rats with gliomas at 18-days old (Group C), eight rats with orthotopically injected normal saline served as controls. CT perfusion was performed before and after administration of acetazolamide. Changes in perfusion parameters due to acetazolamide administration were calculated and analyzed. Results Elevated carbon dioxide partial pressure and decreased pH were found in all 32 rats post acetazolamide challenge (P<0.01). Cerebral blood flowpre-challenge was increased in group C (95.0±2.5 ml/100g/min), as compared to group B (80.1±11.3 ml/100g/min) and group A (63.1±2.1 ml/100g/min). Cerebral blood flow percentage changes were detected with a reduction in group C (54.2±4.8%) as compared to controls (111.3±22.2%). Cerebral blood volume pre-challenge was increased in group C (50.8±1.7ml/100g), as compared to group B (45.7±1.9 ml/100g) and group A (38.2±0.8 ml/100g). Cerebral blood volume percentage changes were decreased in group C (23.5±4.6%) as compared to controls (113.5±30.4%). Angiogenesis ratio = [(CD105-MVD) / (FVIII-MVD)] ×100%. Positive correlations were observed between CD105-microvessel density, angiogenesis ratio, vascular endothelial growth factor, proliferation marker and cerebral blood flowpre-challenge, cerebral blood volume pre-challenge. Negative correlations were observed between CD105-microvessel density and cerebral blood flow percentage changes (P<0.01, correlation coefficient r=-0.788), cerebral blood volume percentage changes (P<0.01, r=-0.703). Negative correlations were observed between angiogenesis ratio, vascular endothelial growth factor

  14. Can acetazolamide be used to treat diseases involving increased bone mineral density?

    PubMed Central

    González-Rodríguez, Juan David; Luis-Yanes, María Isabel; Inglés-Torres, Esther; Arango-Sancho, Pedro; Cabrera-Sevilla, José Eugenio; Duque-Fernández, María Rosario; Gil-Sánchez, Salvador; García-Nieto, Víctor Manuel

    2016-01-01

    Summary Sclerosing bone dysplasias are a series of clinically and genetically heterogeneous diseases characterized by functional failure of the osteoclasts in bone resorption, leading to an excessive amount of bone mineral density (BMD) which could have serious clinical consequences. We treated three children affected with seriously high levels of BMD with acetazolamide, with the intention of inducing metabolic acidosis, thus increasing bone resorption and reducing BMD. All our patients tolerated and followed the treatment well and the clinical response was satisfactory in all cases. PMID:27904825

  15. Two-dimensional crystal structure of aquaporin-4 bound to the inhibitor acetazolamide

    PubMed Central

    Kamegawa, Akiko; Hiroaki, Yoko; Tani, Kazutoshi; Fujiyoshi, Yoshinori

    2016-01-01

    Acetazolamide (AZA) reduces the water permeability of aquaporin-4, the predominant water channel in the brain. We determined the structure of aquaporin-4 in the presence of AZA using electron crystallography. Most of the features of the 5-Å density map were consistent with those of the previously determined atomic model. The map showed a protruding density from near the extracellular pore entrance, which most likely represents the bound AZA. Molecular docking simulations supported the location of the protrusion as the likely AZA-binding site. These findings suggest that AZA reduces water conduction by obstructing the pathway at the extracellular entrance without inducing a large conformational change in the protein. PMID:26908838

  16. Correlation between cerebral oxygen metabolism and cerebral blood flow simultaneously measured before and after acetazolamide administration

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroichiro; Yamauchi, Hideto; Hazama, Shiro; Hamamoto, Hirotsugu; Inoue, Nobuhiro

    1999-10-01

    The cerebral circulation and metabolism of ten preoperative cardiac surgery patients were assessed. Alterations in regional cerebral blood flow (rCBF), measured by 123I-N- isopropyl-p-iodo-amphetamine single-photon emission computed tomography, and in cerebral oxygen metabolism, simultaneously detected by near-infrared spectroscopy (NIRS) before and after acetazolamide administration, were investigated. The rCBF (ml/min/100 g) increased significantly from 40.21 +/- 7.65 to 56.24 +/- 13.69 (p equals 0.001), and a significant increase in oxyhemoglobin (Oxy-Hb) of 13.9% (p equals 0.0022) and total hemoglobin (Total-Hb) of 5.7% (0.0047) along with a significant decrease in deoxyhemoglobin (Deoxy-Hb) of 8.9% (p equals 0.0414) were observed concomitantly. Thus, the Oxy-Hb/Total- Hb ratio (%Oxy-Hb) rose significantly from 67.26 +/- 9.82% to 72.98 +/- 8.09% (p equals 0.0022). Examination of the relationships between individual parameters showed that the percentage changes in rCBF and Oxy-Hb were significantly correlated (r equals 0.758, p equals 0.011). The percentage changes in rCBF and %Oxy-Hb were also correlated significantly (r equals 0.740, p equals 0.014). In conclusion, this evidence suggested that NIRS is able to detect relative changes in cerebral hemodynamics and reflect luxury perfusion induced by acetazolamide.

  17. Treatment of idiopathic intracranial hypertension: topiramate vs acetazolamide, an open-label study.

    PubMed

    Celebisoy, N; Gökçay, F; Sirin, H; Akyürekli, O

    2007-11-01

    OBJECTIVES - To assess the efficacy of topiramate in the treatment of idiopathic intracranial hypertension (IIH) and to compare it with acetazolamide. METHODS - Fourty patients diagnosed as IIH and randomly assigned to treatment with either acetazolamide or topiramate were assessed prospectively. Improvement in the visual fields at the end of third, sixth and twelfth months were taken into consideration. RESULTS - The demographic, clinical features and the cerebrospinal fluid (CSF) pressure of the two treatment groups were similar at the beginning of the study. When the follow-up visual field grades were compared with the visual field grades at the beginning of the study in each group a statistically significant improvement was detected with both drugs. When the results of the two treatment groups were compared with each other no statistically significant difference was present. Prominent weight loss was recorded in the topiramate group. CONCLUSIONS - Topiramate seems to be effective in the treatment of IIH. Weight reduction as well as the reduction of the CSF formation is the possible mechanism of action.

  18. Acetazolamide Oral

    MedlinePlus

    ... heartbeat, diflunisal (Dolobid), digoxin (Lanoxin), diuretics ('water pills'), lithium (Eskalith, Lithobid), phenobarbital, primidone (Mysoline), and vitamins.tell your doctor if you have or have ever had heart, liver, or kidney disease; or diabetes.tell your doctor if you are ...

  19. Use of acetazolamide to decrease cerebrospinal fluid production in chronically ventilated patients with ventriculopleural shunts

    PubMed Central

    Carrion, E; Hertzog, J; Medlock, M; Hauser, G; Dalton, H

    2001-01-01

    Acetazolamide (ACTZ), a carbonic anhydrase inhibitor, has been shown to decrease cerebrospinal fluid (CSF) production in both in vivo and in vitro animal models. We report two children with hydrocephalus who experienced multiple shunt failures, and who had externalised ventriculostomy drains (EVD) prior to ventriculopleural shunt placement. The effects of increasing doses of ACTZ on CSF production and subsequent tolerance to ventriculopleural shunts were evaluated. The patients had a 48% and a 39% decrease in their EVD CSF output when compared to baseline with maximum ACTZ dose of 75 mg/kg/day and 50 mg/kg/day, respectively (p < 0.05). This is the first report of change in CSF volume in children after extended treatment with ACTZ. ACTZ treatment in mechanically ventilated paediatric patients with hydrocephalus may improve tolerance of ventriculopleural shunts and minimise respiratory compromise. Potassium and bicarbonate supplements are required to correct metabolic disturbances.

 PMID:11124792

  20. Hereditary myokymia and paroxysmal ataxia linked to chromosome 12 is responsive to acetazolamide.

    PubMed Central

    Lubbers, W J; Brunt, E R; Scheffer, H; Litt, M; Stulp, R; Browne, D L; van Weerden, T W

    1995-01-01

    A sixth family with autosomal dominantly inherited myokymia and paroxysmal ataxia is described. The syndrome in this family is linked to the recently discovered locus for inherited myokymia and paroxysmal ataxia on the human chromosome 12p, and a missense mutation is shown in the KCNA1 gene. The attacks of ataxia in this family compare well with those of previously described families and similarly are precipitated by kinesigenic stimuli, exertion, and startle. Responsiveness of these attacks to low dose acetazolamide is confirmed, but some loss of efficacy occurs with prolonged treatment, and side effects are notable. Although not all affected family members showed myokymia on clinical examination, electromyography invariably showed myokymic discharges, in one patient only after a short provocation with regional ischaemia. One affected family member also had attacks of paroxysmal kinesigenic choreoathetosis, responsive to carbamazepine. PMID:7561920

  1. Introducing treatment strategy for cerebellar ataxia in mutant med mice: combination of acetazolamide and 4-aminopyridine.

    PubMed

    Abbasi, Samira; Abbasi, Ataollah; Sarbaz, Yashar

    2014-02-01

    Purkinje neurons are the sole output neuron of the cerebellar cortex, and they generate high-frequency action potentials. Electrophysiological dysfunction of Purkinje neurons causes cerebellar ataxia. Mutant med mice have the lack of expression of the Scn8a gene. This gene encodes the NaV1.6 protein. In med Purkinje neurons, regular high-frequency firing is slowed, and med mice are ataxic. The aim of this study was to propose the neuroprotective drugs which could be useful for ataxia treatment in med mice, and to investigate the neuroprotective effects of these drugs by simulation. Simulation results showed that Kv4 channel inhibitors and BK channel activators restored the normal electrophysiological properties of the med Purkinje neurons. 4-Aminopyridine (4-AP) and acetazolamide (ACTZ) were proposed as neuroprotective drugs for Kv4 channel inhibitor and BK channel activator, respectively.

  2. Correlation between cerebral oxygen metabolism and cerebral blood flow simultaneously measured before and after acetazolamide administration.

    PubMed

    Yamaguchi, H; Yamauchi, H; Hazama, S; Hamamoto, H; Inoue, N

    1999-10-01

    The cerebral circulation and metabolism of ten preoperative cardiac surgery patients were assessed. Alterations in regional cerebral blood flow (rCBF), measured by 123I-N-isopropyl-p-iodo-amphetamine single-photon emission computed tomography, and in cerebral oxygen metabolism, simultaneously detected by near-infrared spectroscopy (NIRS) before and after acetazolamide administration, were investigated. The rCBF (ml/min/100 g) increased significantly from 40.21±7.65 to 56.24±13.69(p<0.001), and a significant increase in oxyhemoglobin (Oxy-Hb) of 13.9% (p=0.0022) and total hemoglobin (Total-Hb) of 5.7% (0.0047) along with a significant decrease in deoxyhemoglobin (Deoxy-Hb) of 8.9% (p=0.0414) were observed concomitantly. Thus, the Oxy-Hb/Total-Hb ratio (%Oxy-Hb) rose significantly from 67.26±9.82% to 72.98±8.09%(p=0.0022). Examination of the relationships between individual parameters showed that the percentage changes in rCBF and Oxy-Hb were significantly correlated (r=0.758,p=0.011). The percentage changes in rCBF and %Oxy-Hb were also correlated significantly (r=0.740,p=0.014). In conclusion, this evidence suggested that NIRS is able to detect relative changes in cerebral hemodynamics and reflect luxury perfusion induced by acetazolamide. © 1999 Society of Photo-Optical Instrumentation Engineers.

  3. Benzolamide improves oxygenation and reduces acute mountain sickness during a high-altitude trek and has fewer side effects than acetazolamide at sea level.

    PubMed

    Collier, David J; Wolff, Chris B; Hedges, Anne-Marie; Nathan, John; Flower, Rod J; Milledge, James S; Swenson, Erik R

    2016-06-01

    Acetazolamide is the standard carbonic anhydrase (CA) inhibitor used for acute mountain sickness (AMS), however some of its undesirable effects are related to intracellular penetrance into many tissues, including across the blood-brain barrier. Benzolamide is a much more hydrophilic inhibitor, which nonetheless retains a strong renal action to engender a metabolic acidosis and ventilatory stimulus that improves oxygenation at high altitude and reduces AMS. We tested the effectiveness of benzolamide versus placebo in a first field study of the drug as prophylaxis for AMS during an ascent to the Everest Base Camp (5340 m). In two other studies performed at sea level to test side effect differences between acetazolamide and benzolamide, we assessed physiological actions and psychomotor side effects of two doses of acetazolamide (250 and 1000 mg) in one group of healthy subjects and in another group compared acetazolamide (500 mg), benzolamide (200 mg) and lorazepam (2 mg) as an active comparator for central nervous system (CNS) effects. At high altitude, benzolamide-treated subjects maintained better arterial oxygenation at all altitudes (3-6% higher at all altitudes above 4200 m) than placebo-treated subjects and reduced AMS severity by roughly 50%. We found benzolamide had fewer side effects, some of which are symptoms of AMS, than any of the acetazolamide doses in Studies 1 and 2, but equal physiological effects on renal function. The psychomotor side effects of acetazolamide were dose dependent. We conclude that benzolamide is very effective for AMS prophylaxis. With its lesser CNS effects, benzolamide may be superior to acetazolamide, in part, because some of the side effects of acetazolamide may contribute to and be mistaken for AMS.

  4. Acetazolamide on the ventral medulla of the cat increases phrenic output and delays the ventilatory response to CO2.

    PubMed Central

    Coates, E L; Li, A H; Nattie, E E

    1991-01-01

    1. Acetazolamide (0.1 mM) applied to the surface of the rostral ventrolateral medulla or microinjected beneath the medullary surface in chloralose-urethane-anaesthetized, vagotomized, carotid-denervated, paralysed, servo-ventilated cats produced a long-lasting increase in integrated phrenic nerve activity. 2. Extracellular pH measured beneath the rostral ventrolateral medulla exhibited a long-lasting decrease after surface acetazolamide but was not a good predictor, in each individual animal, of changes in phrenic activity. 3. Medullary carbonic anhydrase inhibition reduced the slope and the half-time of the phrenic response to rapid step CO2 increases. Conversely, acetazolamide did not affect the phrenic response to steady-state CO2 increases. 4. These data indicate that localized inhibition of medullary carbonic anhydrase causes a centrally mediated increase in ventilation that we attribute to medullary tissue hypercapnia and acidosis. In addition, these data indicate that medullary carbonic anhydrase may play a role in central CO2 chemotransduction. Images Fig. 8 PMID:1816381

  5. The effects of acetazolamide and spironolactone on the body water distribution of rabbits during acute exposure to simulated altitude

    NASA Astrophysics Data System (ADS)

    Jain, S. C.; Singh, M. V.; Rawal, S. B.

    1984-06-01

    The role of body water metabolism on acute altitude exposure was studied. The studies were carried out in rabbits divided into four groups, namely, (i) control, (ii) exposed to acute hypoxia, (iii) exposed to acute hypoxia after treatment with 250 mg acetazolamide and (iv) exposed to acute hypoxia after treatment with 25 mg spironolactone. Total body water, extracellular water, intracellular water and blood volume decreased by an insignificant amount on exposure to hypoxia and plasma volume decreased by 5.7% (P<0.025). Treatment with either acetazolamide or spironolactone resulted in further marginal decrease in total body water. In the case of acetazolamide, the loss occurs from both intracellular and extracellular compartments, while treatment with spironolactone resulted in significant loss only from extracellular compartment. Treatment with both the drugs resulted in a small rise in pO2 and pCO2 with a slight decrease in pH. Our data suggested spironolactone to be a better prophylactic agent for use on acute high altitude induction.

  6. Endolymphatic Hydrops Reversal following Acetazolamide Therapy: Demonstration with Delayed Intravenous Contrast-Enhanced 3D-FLAIR MRI.

    PubMed

    Sepahdari, A R; Vorasubin, N; Ishiyama, G; Ishiyama, A

    2016-01-01

    Endolymphatic hydrops, the primary pathologic alteration in Menière disease, can be visualized by using delayed intravenous contrast-enhanced 3D-FLAIR MR imaging. It is not known whether MR imaging-demonstrable changes of hydrops fluctuate with disease activity or are fixed. We describe the results of baseline and posttreatment MR imaging studies in a group of subjects with Menière disease with hydrops who were treated with acetazolamide. Seven subjects with untreated Menière disease with MR imaging evidence of hydrops had repeat MR imaging during acetazolamide treatment. Symptoms and imaging findings were assessed at each time point. Five subjects showed symptom improvement, of whom 3 had improvement or resolution of hydrops. One subject had recurrent symptoms with recurrent hydrops after discontinuing therapy. Two had unchanged hydrops despite symptom improvement. Subjects with unchanged symptoms had unchanged hydrops. Hydrops reversal may be seen with acetazolamide treatment in Menière disease. MR imaging may provide an additional biomarker of disease.

  7. Patients with Obstructive Sleep Apnea Have Cardiac Repolarization Disturbances when Travelling to Altitude: Randomized, Placebo-Controlled Trial of Acetazolamide

    PubMed Central

    Latshang, Tsogyal Daniela; Kaufmann, Barbara; Nussbaumer-Ochsner, Yvonne; Ulrich, Silvia; Furian, Michael; Kohler, Malcolm; Thurnheer, Robert; Saguner, Ardan Muammer; Duru, Firat; Bloch, Konrad Ernst

    2016-01-01

    Study Objectives: Obstructive sleep apnea (OSA) promotes myocardial electrical instability and may predispose to nocturnal sudden cardiac death. We evaluated whether hypobaric hypoxia during altitude travel further impairs cardiac repolarization in patients with OSA, and whether this is prevented by acetazolamide, a drug known to improve oxygenation and central sleep apnea at altitude. Methods: Thirty-nine OSA patients living < 600 m, discontinued continuous positive airway pressure therapy during studies at 490 m and during two sojourns of 3 days at altitude (2 days at 1860 m, 1 day at 2590 m). During one altitude sojourn, patients took acetazolamide, during the other placebo, or vice versa, according to a randomized, double-blind crossover design. Twelve-lead electrocardiography and pulse oximetry (SpO2) were recorded during nocturnal polysomnography. Heart rate corrected mean QT intervals during the entire night (meanQTc) and during 1 min of the night with the longest meanQTc (maxQTc) were determined. Results: At 490 m the median nocturnal SpO2 was 93%, medians of meanQTc and maxQTc were 420 ms and 478 ms. At 2590 m, on placebo, SpO2 was lower (85%), and meanQTc and maxQTc were prolonged to 430 ms and 510 ms (P < 0.02 vs. 490 m, all corresponding comparisons). At 2590 m on acetazolamide, median SpO2 was increased to 88% (P < 0.05 vs. placebo), meanQTc was reduced to 427 ms (P < 0.05 vs. placebo), whereas maxQTc remained increased at 502 ms (P = ns vs. placebo). Conclusions: At 2590 m OSA patients experienced cardiac repolarization disturbances in association with hypoxemia. Prolongation of meanQTc at altitude was prevented and hypoxemia was improved by acetazolamide, whereas maxQTc remained increased suggesting imperfect protection from repolarization disturbances. Clinical Trial Registration: ClinicalTrials.gov ID: NTC-00714740. URL: www.clinicaltrials.gov Citation: Latshang TD, Kaufmann B, Nussbaumer-Ochsner Y, Ulrich S, Furian M, Kohler M, Thurnheer R

  8. Interrelation of the dissolution behavior and solid-state features of acetazolamide cocrystals.

    PubMed

    Arenas-García, Jenniffer I; Herrera-Ruiz, Dea; Morales-Rojas, Hugo; Höpfl, Herbert

    2017-01-01

    The thermal behavior, phase stability, indicative stability and intrinsic dissolution rates of a series of cocrystals and cocrystal hydrates derived from the pharmaceutically active ingredient acetazolamide (ACZ) and 2-aminobenzamide (2ABAM), 2,3-dihydroxybenzoic acid (23DHBA), 2-hydroxybenzamide (2HBAM), 4-hydroxybenzoic acid (4HBA), nicotinamide (NAM) and picolinamide (PAM) as cocrystal formers have been evaluated. Upon heating in an inert atmosphere most of the cocrystals tested demonstrated first the elimination of the crystal former, followed by ACZ degradation. Only in cocrystals with NAM was melting observed. Under controlled temperature and relative humidity conditions all cocrystals tested were stable. However, phase stability tests in a medium simulating physiological conditions (HCl 0.01N, pH2.0) indicated that cocrystals ACZ-NAM-H2O and ACZ-PAM gradually transform into ACZ. All cocrystals examined gave enhanced intrinsic dissolution rates when compared to pure ACZ and the largest dissolution rate constants were measured for the cocrystals that transformed in the phase stability test (approximate two-fold increase of the dissolution rate constants). The series of cocrystals examined herein exhibits an inverse correlation between the intrinsic dissolution rates and the melting/decomposition temperatures as well as the dimension of the hydrogen-bonded ACZ aggregates found in the corresponding crystal structure, indicating that solid-state stability is the major influence on dissolution performance.

  9. Is acetazolamide similar to topiramate for reversal of antipsychotic-induced weight gain?

    PubMed

    Schneiderhan, Mark E; Marvin, Robert

    2007-01-01

    Acetazolamide (AZD), a sulfa-like moiety, is a potent, nonspecific inhibitor of carbonic anhydrase (CA) enzymes and has been demonstrated to decrease lipogenesis in adipose cells in in vitro cell culture studies. In contrast, topiramate (a sulfamate moiety) appears to inhibit specific (CA) enzymes II and V. Four placebo-controlled trials with topiramate have demonstrated positive results in weight loss. There is only anecdotal evidence that AZD may cause weight loss. The following case is of a 49-year-old African-American woman with a long history of schizoaffective disorder, hypertension, diabetes type II, stress incontinence, and obesity (body mass index, 45.5 kg/m2). Previous trials of topiramate demonstrated temporary but significant weight loss before AZD use. A 4 week washout period occurred before starting AZD, 250 mg twice daily. Significant weight loss of 11.5 lbs was seen over 4 weeks. During washout periods of either topiramate or AZD, her total mean weight was approximately 2 to 7 lbs higher than when she was treated with AZD. Although tolerance and side effects may limit the use of AZD as a safe and effective strategy for medication-related weight gain, the pharmacology may provide research insights into the causes and treatments of obesity.

  10. Legionella pneumophila Carbonic Anhydrases: Underexplored Antibacterial Drug Targets

    PubMed Central

    Supuran, Claudiu T.

    2016-01-01

    Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including Legionella pneumophila, have been cloned and characterized in detail. These enzymes were shown to be efficient catalysts for CO2 hydration, with kcat values in the range of (3.4–8.3) × 105 s−1 and kcat/KM values of (4.7–8.5) × 107 M−1·s−1. In vitro inhibition studies with various classes of inhibitors, such as anions, sulfonamides and sulfamates, were also reported for the two β-CAs from this pathogen, LpCA1 and LpCA2. Inorganic anions were millimolar inhibitors, whereas diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid, and phenylarsonic acid were micromolar ones. The best LpCA1 inhibitors were aminobenzolamide and structurally similar sulfonylated aromatic sulfonamides, as well as acetazolamide and ethoxzolamide (KIs in the range of 40.3–90.5 nM). The best LpCA2 inhibitors belonged to the same class of sulfonylated sulfonamides, together with acetazolamide, methazolamide, and dichlorophenamide (KIs in the range of 25.2–88.5 nM). Considering such preliminary results, the two bacterial CAs from this pathogen represent promising yet underexplored targets for obtaining antibacterials devoid of the resistance problems common to most of the clinically used antibiotics, but further studies are needed to validate them in vivo as drug targets. PMID:27322334

  11. Effect of acetazolamide on pulmonary and muscle gas exchange during normoxic and hypoxic exercise.

    PubMed

    Jonk, Amy M; van den Berg, Irene P; Olfert, I Mark; Wray, D Walter; Arai, Tatsuya; Hopkins, Susan R; Wagner, Peter D

    2007-03-15

    Acetazolamide (ACZ) is used to prevent acute mountain sickness at altitude. Because it could affect O2 transport in several different and potentially conflicting ways, we examined its effects on pulmonary and muscle gas exchange and acid-base status during cycle exercise at approximately 30, 50 and 90% VO2max in normoxia (F(IO2) = 0.2093) and acute hypoxia (F(IO2) = 0.125). In a double-blind, order-balanced, crossover design, six healthy, trained men (normoxic VO2max= 59 ml kg(-1) min(-1)) exercised at both F(IO2) values after ACZ (3 doses of 250 mg, 8 h apart) and placebo. One week later this protocol was repeated using the other drug (placebo or ACZ). We measured cardiac output (QT), leg blood flow (LBF), and muscle and pulmonary gas exchange, the latter using the multiple inert gas elimination technique. ACZ did not significantly affect VO2, QT, LBF or muscle gas exchange. As expected, ACZ led to lower arterial and venous blood [HCO3-], pH and lactate levels (P < 0.05), and increased ventilation (P < 0.05). In both normoxia and hypoxia, ACZ resulted in higher arterial P(O2) and saturation and a lower alveolar-arterial P(O2) difference (AaD(O2)) due to both less VA/Q mismatch and less diffusion limitation (P < 0.05). In summary, ACZ improved arterial oxygenation during exercise, due to both greater ventilation and more efficient pulmonary gas exchange. However, muscle gas exchange was unaffected.

  12. Rebound macular edema following oral acetazolamide therapy for juvenile X-linked retinoschisis in an Italian family

    PubMed Central

    Galantuomo, Maria Silvana; Fossarello, Maurizio; Cuccu, Alberto; Farci, Roberta; Preising, Markus N; Lorenz, Birgit; Napoli, Pietro Emanuele

    2016-01-01

    Background Juvenile X-linked retinoschisis (RS1, OMIM: 312700) is a hereditary vitreoretinal dystrophy characterized by bilateral foveal schisis and, in half of the patients, splitting through the nerve fiber layer in the peripheral retina. In the first decade of life, patients usually develop a decrease in visual acuity. Long-term visual outcomes can be poor due to the limited number of known successful treatments. Purpose The purposes of this study were to present, for the first time, a p.Arg197Cys missense mutation in the RS1 gene (OMIM: 300839) in a four-generation Italian family with RS1 and to examine the clinical response to the treatment with acetazolamide tablets alone or in combination with dorzolamide eye drops as assessed by spectral-domain optical coherence tomography (SD-OCT). Methods Eleven individuals, including two brothers with RS1 (patients 1 and 2), underwent a full medical history examination and a comprehensive ocular assessment that involved SD-OCT, fluorescein angiography, electroretinography and DNA analysis. Each RS1 patient received oral acetazolamide (375 mg daily) during the first three months. Thereafter, patient 1 continued only with dorzolamide eyedrops three times a day for a period of three months, while patient 2 spontaneously stopped both medications. Results Sequence analysis of the RS1 gene identified a hemizygous c.589C>T (p.Arg197Cys) missense mutation in exon 6, which has not been previously reported in an Italian family. A different response to the medical therapy was observed in the four eyes of the two affected brothers hemizygous for this abnormality. Of note, after acetazolamide interruption, a rebound effect on cystoid macular edema reduced the beneficial effects of the initial therapy for RS1 from p.Arg197Cys mutation. Indeed, a minimal rebound effect on cystoid macular edema, and an improvement in visual acuity, was observed in patient 1 during the six months of treatment. Conversely, in patient 2, an initial

  13. Effects of cryoprotectants on the structure and thermostability of the human carbonic anhydrase II–acetazolamide complex

    SciTech Connect

    Aggarwal, Mayank; Boone, Christopher D.; Kondeti, Bhargav; Tu, Chingkuang; Silverman, David N.; McKenna, Robert

    2013-05-01

    Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Protein X-ray crystallography has seen a progressive shift from data collection at cool/room temperature (277–298 K) to data collection at cryotemperature (100 K) because of its ease of crystal preparation and the lessening of the detrimental effects of radiation-induced crystal damage, with 20–25%(v/v) glycerol (GOL) being the preferred choice of cryoprotectant. Here, a case study of the effects of cryoprotectants on the kinetics of carbonic anhydrase II (CA II) and its inhibition by the clinically used inhibitor acetazolamide (AZM) is presented. Comparative studies of crystal structure, kinetics, inhibition and thermostability were performed on CA II and its complex with AZM in the presence of either GOL or sucrose. These results suggest that even though the cryoprotectant GOL was previously shown to be directly bound in the active site and to interact with AZM, it affects neither the thermostability of CA II nor the binding of AZM in the crystal structure or in solution. However, addition of GOL does affect the kinetics of CA II, presumably as it displaces the water proton-transfer network in the active site.

  14. Washout rate in rat brain irradiated by a 11C beam after acetazolamide loading using a small single-ring OpenPET prototype

    NASA Astrophysics Data System (ADS)

    Hirano, Yoshiyuki; Takuwa, Hiroyuki; Yoshida, Eiji; Nishikido, Fumihiko; Nakajima, Yasunori; Wakizaka, Hidekatsu; Yamaya, Taiga

    2016-03-01

    In dose verification techniques of particle therapies based on in-beam positron emission tomography (PET), the causes of washout of positron emitters by physiological effects should be clarified to correct washout for accurate verification. As well, the quantitative washout rate has a potential usefulness as a diagnostic index which should be explored. Therefore, we measured washout rates of rat brain after vasodilator acetazolamide loading to investigate the possible effects of blood flow on washout. Six rat brains were irradiated by a radioisotope 11C beam and time activity curves on the whole brains were obtained with a small single-ring OpenPET prototype. Then, washout rates were calculated with the Mizuno model, where two washout rates (k 2m and k 2s ) were assumed, and a two-compartment model including efflux from tissue to blood (k 2) and influx (k 3) and efflux (k 4) between the two tissue compartments. Before the irradiations, we used laser-Doppler flowmetry to confirm that acetazolamide increased cerebral blood flow (CBF) of a rat. We compared means of k 2m , k 2s and k 2, k 3 and k 4 without acetazolamide loading (Rest) and with acetazolamide loading (ACZ). For all k values, ACZ values were lower than Rest values. In other words, though CBF increased, washout rates were decreased. This may be attributed to the implanted 11C reacting to form 11CO2. Because acetazolamide increased the concentration of CO2 in brain, suppressed diffusion of 11CO2 and decomposition of 11CO2 into ions were prevented.

  15. High-resolution structure of human carbonic anhydrase II complexed with acetazolamide reveals insights into inhibitor drug design.

    PubMed

    Sippel, Katherine H; Robbins, Arthur H; Domsic, John; Genis, Caroli; Agbandje-McKenna, Mavis; McKenna, Robert

    2009-10-01

    The crystal structure of human carbonic anhydrase II (CA II) complexed with the inhibitor acetazolamide (AZM) has been determined at 1.1 A resolution and refined to an R(cryst) of 11.2% and an R(free) of 14.7%. As observed in previous CA II-inhibitor complexes, AZM binds directly to the zinc and makes several key interactions with active-site residues. The high-resolution data also showed a glycerol molecule adjacent to the AZM in the active site and two additional AZMs that are adventitiously bound on the surface of the enzyme. The co-binding of AZM and glycerol in the active site demonstrate that given an appropriate ring orientation and substituents, an isozyme-specific CA inhibitor may be developed.

  16. Linker stability influences the anti-tumor activity of acetazolamide-drug conjugates for the therapy of renal cell carcinoma

    PubMed Central

    Neri, Dario

    2016-01-01

    Small molecule-drug conjugates (SMDCs) are increasingly being considered as an alternative to antibody-drug conjugates (ADCs) for the selective delivery of anticancer agents to the tumor site, sparing normal tissues. Carbonic anhydrase IX (CAIX) is a membrane-bound enzyme, which is over-expressed in the majority of renal cell carcinomas and which can be efficiently targeted in vivo, using charged derivatives of acetazolamide, a small heteroaromatic sulfonamide. Here, we show that SMDC products, obtained by the coupling of acetazolamide with monomethyl auristatin E (MMAE) using dipeptide linkers, display a potent anti-tumoral activity in mice bearing xenografted SKRC-52 renal cell carcinomas. A comparative evaluation of four dipeptides revealed that SMDCs featuring valine-citrulline and valine-alanine linkers exhibited greater serum stability and superior therapeutic activity, compared to the counterparts with valine-lysine or valine-arginine linkers. The most active products substantially inhibited tumor growth over a prolonged period of time, in a tumor model for which sunitinib and sorafenib do not display therapeutic activity. However, complete tumor eradication was not possible even after ten intravenous injection. Macroscopic near-infrared imaging procedures confirmed that ligands had not lost the ability to selectively localize at the tumor site at the end of therapy and that the neoplastic masses continued to express CAIX. The findings are of mechanistic and of therapeutic significance, since CAIX is a non-internalizing membrane-associated antigen, which can be considered for targeted drug delivery applications in kidney cancer patients. PMID:27890855

  17. Sildenafil, nifedipine and acetazolamide do not allow for blood flow through intrapulmonary arteriovenous anastomoses during exercise while breathing 100% oxygen.

    PubMed

    Elliott, Jonathan E; Friedman, Jonathan M; Futral, Joel E; Goodman, Randall D; Lovering, Andrew T

    2014-12-01

    Blood flow through intrapulmonary arteriovenous anastomoses (IPAVAs) is known to increase in healthy humans during exercise while breathing room air, but is prevented or significantly reduced during exercise while breathing 100% O2, potentially due to vasoconstriction of IPAVAs. Thus, pharmacological interventions that target known pathways regulating the cardiopulmonary circulation may be able to prevent the hyperoxia-induced reduction in IPAVA blood flow (Q̇ IPAVA ) during exercise. In nine healthy human subjects, we investigated the effects of sildenafil (100 mg p.o.), nifedipine (20 mg p.o.) and acetazolamide (250 mg p.o. three times a day for 3 days) on Q̇ IPAVA at rest and during cycle ergometer exercise at 50, 100, 150, 200 and 250 W, while breathing room air (normoxia) and 100% O2 (hyperoxia). Transthoracic saline contrast echocardiography and a 0-5 bubble scoring system were used to detect and assess Q̇ IPAVA qualitatively; ultrasound was used to assess the blood flow velocity oftricuspid regurgitation and the left ventricular outflow tract blood flow to calculate pulmonary artery systolic pressure (PASP) and cardiac output, respectively. Without drugs, bubble scores increased significantly to ≥2 at 150 W in normoxia and to ≤2 at 200 W in hyperoxia. Only nifedipine consistently increased cardiac output at rest and during low-intensity exercise in normoxia and hyperoxia. However, there was no detectable effect of any drug on Q̇ IPAVA ; specifically, bubble scores were the same during exercise in either normoxia or hyperoxia. Accordingly, the reduction in Q̇ IPAVA during exercise while breathing 100% O2 is likely not to be due to the independent pharmacological mechanisms of action associated with sildenafil, nifedipine or acetazolamide.

  18. Design of a carbonic anhydrase IX active-site mimic to screen inhibitors for possible anticancer properties.

    PubMed

    Genis, Caroli; Sippel, Katherine H; Case, Nicolette; Cao, Wengang; Avvaru, Balendu Sankara; Tartaglia, Lawrence J; Govindasamy, Lakshmanan; Tu, Chingkuang; Agbandje-McKenna, Mavis; Silverman, David N; Rosser, Charles J; McKenna, Robert

    2009-02-17

    Recently, a convincing body of evidence has accumulated suggesting that the overexpression of carbonic anhydrase isozyme IX (CA IX) in some cancers contributes to the acidification of the extracellular matrix, which in turn promotes the growth and metastasis of the tumor. These observations have made CA IX an attractive drug target for the selective treatment of certain cancers. Currently, there is no available X-ray crystal structure of CA IX, and this lack of availability has hampered the rational design of selective CA IX inhibitors. In light of these observations and on the basis of structural alignment homology, using the crystal structure of carbonic anhydrase II (CA II) and the sequence of CA IX, a double mutant of CA II with Ala65 replaced by Ser and Asn67 replaced by Gln has been constructed to resemble the active site of CA IX. This CA IX mimic has been characterized kinetically using (18)O-exchange and structurally using X-ray crystallography, alone and in complex with five CA sulfonamide-based inhibitors (acetazolamide, benzolamide, chlorzolamide, ethoxzolamide, and methazolamide), and compared to CA II. This structural information has been evaluated by both inhibition studies and in vitro cytotoxicity assays and shows a correlated structure-activity relationship. Kinetic and structural studies of CA II and CA IX mimic reveal chlorzolamide to be a more potent inhibitor of CA IX, inducing an active-site conformational change upon binding. Additionally, chlorzolamide appears to be cytotoxic to prostate cancer cells. This preliminary study demonstrates that the CA IX mimic may provide a useful model to design more isozyme-specific CA IX inhibitors, which may lead to development of new therapeutic treatments of some cancers.

  19. Synthesis, characterization and in vitro release studies of a new acetazolamide-HP-beta-CD-TEA inclusion complex.

    PubMed

    Granero, Gladys E; Maitre, Marcos M; Garnero, Claudia; Longhi, Marcela R

    2008-03-01

    The aim of our work was to develop a multicomponent inclusion complex of acetazolamide (ACZ) in order to investigate the combined effect of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and triethanolamine (TEA) on the solubility of ACZ and its possibility of ophthalmic delivery. Phase solubility study was used to evaluate the complexation in solution at 25 degrees C. Complex formation was also evaluated by comparing the infrared (FT-IR) spectra of the solid complexes with a simple physical mixture containing the same amount of ACZ. FT-IR experiments provided data indicating that the carbonamido group of ACZ is involved in the inclusion process. In vitro release data showed that both formulations, containing the freeze-dried ternary complex and the corresponding simple physical mixture of ACZ with HP-beta-CD and TEA presented the fastest release rate of ACZ. These results suggest that the ACZ-HP-beta-CD-TEA complex represents an effective novel formulation to enhance ACZ solubility in water, turning it promising for ophthalmic administration.

  20. Effects of operational conditions on the supercritical solvent impregnation of acetazolamide in Balafilcon A commercial contact lenses.

    PubMed

    Braga, Mara E M; Costa, Viviana P; Pereira, Mário J T; Fiadeiro, Paulo T; Gomes, Ana Paula A R; Duarte, Catarina M M; de Sousa, Hermínio C

    2011-11-28

    In this work we employed a supercritical solvent impregnation (SSI) process using a scCO(2)+EtOH (5% molar) solvent mixture to impregnate acetazolamide (ACZ) into commercially available silicone-based soft contact lenses (Balafilcon A, Pure Vision, Bausch & Lomb). Contact lenses (SCLs) drug-loading was studied at 40°C and 50°C, and from 15 MPa up to 20 MPa, and using low depressurization rates in order to avoid any harm to SCLs. The effect of impregnation processing time on the loaded ACZ amounts was also studied (1, 2 and 3h). In vitro drug release kinetics studies were performed and the released ACZ was quantified spectrophotometrically. Several analytical techniques were employed in order to characterize the processed and non-processed SCLs in terms of some of their important functional properties. Obtained results demonstrated that ACZ-loaded therapeutic Balafilcon A SCLs can be successfully prepared using the employed SSI process. Furthermore, it was possible to control ACZ loaded amounts and, consequently, to adjust the final ACZ release levels into the desired therapeutic limits, just by changing the employed operational conditions (P, T, processing time and depressurization rate) and without change some of their most important thermomechanical, surface/wettability and optical properties. Obtained soft contact lenses can be potentially employed as combined biomedical devices for simultaneous therapeutic and correction of refractive deficiencies purposes.

  1. Molecular dynamics study of human carbonic anhydrase II in complex with Zn(2+) and acetazolamide on the basis of all-atom force field simulations.

    PubMed

    Wambo, Thierry O; Chen, Liao Y; McHardy, Stanton F; Tsin, Andrew T

    2016-01-01

    Human carbonic anhydrase II (hCAII) represents an ultimate example of the perfectly efficient metalloenzymes, which is capable of catalyzing the hydration of carbon dioxide with a rate approaching the diffusion controlled limit. Extensive experimental studies of this physiologically important metalloprotein have been done to elucidate the fundamentals of its enzymatic actions: what residues anchor the Zn(2+) (or another divalent cation) at the bottom of the binding pocket; how the relevant residues work concertedly with the divalent cation in the reversible conversions between CO2 and HCO3(-); what are the protonation states of the relevant residues and acetazolamide, an inhibitor complexed with hCAII, etc. In this article, we present a detailed computational study on the basis of the all-atom CHARMM force field where Zn(2+) is represented with a simple model of divalent cation using the transferrable parameters available from the current literature. We compute the hydration free energy of Zn(2+), the characteristics of hCAII-Zn(2+) complexation, and the absolute free energy of binding acetazolamide to the hCAII-Zn(2+) complex. In each of these three problems, our computed results agree with the experimental data within the known margin of error without making any case-by-case adjustments to the parameters. The quantitatively accurate insights we gain in this all-atom molecular dynamics study should be helpful in the search and design of more specific inhibitors of this and other carbonic anhydrases.

  2. Dorzolamide Chlorhydrate Versus Acetazolamide in the Management of Chronic Macular Edema in Patients with Retinitis Pigmentosa: Description of Three Case Reports

    PubMed Central

    Pacella, Elena; Arrico, Loredana; Santamaria, Valentina; Turchetti, Paolo; Carbotti, Maria Rosaria; La Torre, Giuseppe; Pacella, Fernanda

    2014-01-01

    AIMS To assess the efficacy of topical dorzolamide for treating cystoid macular edema in patients with retinitis pigmentosa and minimize the secondary effects of maintenance therapy in patients with retinitis pigmentosa (RP) who present with chronic microcystic macular edema. METHODS To replace acetazolamide systemic treatment, with a topical treatment using 2% dorzolamide in three patients. The methods performed were OCT scan with a Spectralis HRA-OCT, for the measurement of macular thickness and morphology; best corrected visual acuity was assessed using Early Treatment Diabetic Retinopathy Study (ETDRS), was assessed slit-lamp biomicroscopy, ocular tonometry, fundus biomiocrosopy, and color fundus photography. This therapeutic protocol has been applied and described in three patients. RESULTS In all three tested patients, following the administration of dorzolamide in eye drop, we observed a remarkable decrease in macular edema, almost comparable to that obtained with acetazolamide per os. CONCLUSION The study confirms the anti-edematogenic effect of topical dorzolamide in RP with recurring macular cysts, as this can have a favorable response with topical dorzolamide. In all the three examined patients, the instillation of topical dorzolamide caused a remarkable reduction in their macular edema, as highlighted on OCT. PMID:24932106

  3. A validated stability-indicating LC method for acetazolamide in the presence of degradation products and its process-related impurities.

    PubMed

    Srinivasu, Prabha; Subbarao, Devarakonda V; Vegesna, Raju V K; Sudhakar Babu, K

    2010-05-01

    The objective of the current study was to develop a validated, specific and stability-indicating reverse phase liquid chromatographic method for the quantitative determination of acetazolamide and its related substances. The determination was done for an active pharmaceutical ingredient, its pharmaceutical dosage form in the presence of degradation products, and its process-related impurities. The drug was subjected to stress conditions of hydrolysis (acid and base), oxidation, photolysis and thermal degradation as per International Conference on Harmonization (ICH) prescribed stress conditions to show the stability-indicating power of the method. Significant degradation was observed during acid and base hydrolysis, and the major degradant was identified by LC-MS, FTIR and (1)H/(13)C NMR spectral analysis. The chromatographic conditions were optimized using an impurity-spiked solution and the generated samples were used for forced degradation studies. In the developed HPLC method, the resolution between acetazolamide and, its process-related impurities (namely imp-1, imp-2, imp-3, imp-4 and its degradation products) was found to be greater than 2. The chromatographic separation was achieved on a C18, 250mmx4.6mm, 5microm column. The LC method employed a linear gradient elution, and the detection wavelength was set at 254nm. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.6%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.

  4. Efficacy and safety of preoperative IOP reduction using a preservative-free fixed combination of dorzolamide/timolol eye drops versus oral acetazolamide and dexamethasone eye drops and assessment of the clinical outcome of trabeculectomy in glaucoma

    PubMed Central

    Lorenz, Katrin; Wasielica-Poslednik, Joanna; Bell, Katharina; Renieri, Giulia; Keicher, Alexander; Ruckes, Christian; Pfeiffer, Norbert; Thieme, Hagen

    2017-01-01

    Introduction To demonstrate that preoperative treatment for 28 days with topical dorzolamide/timolol is non-inferior (Δ = 4 mm Hg) to oral acetazolamide and topical dexamethasone (standard therapy) in terms of intraocular pressure (IOP) reduction 3 and 6 months after trabeculectomy in glaucoma patients. Materials and methods Sixty-two eyes undergoing trabeculectomy with mitomycin C were included in this monocentric prospective randomized controlled study. IOP change between baseline and 3 months post-op was defined as the primary efficacy variable. Secondary efficacy variables included the number of 5-fluorouracil (5-FU) injections, needlings, suture lyses, preoperative IOP change, hypertension rate and change of conjunctival redness 3 and 6 months post-op. Safety was assessed based on the documentation of adverse events. Results Preoperative treatment with topical dorzolamide/timolol was non-inferior to oral acetazolamide and topical dexamethasone in terms of IOP reduction 3 months after trabeculectomy (adjusted means -8.12 mmHg versus -8.30 mmHg; Difference: 0.18; 95% CI -1.91 to 2.26, p = 0.8662). Similar results were found 6 months after trabeculectomy (-9.13 mmHg versus -9.06 mmHg; p = 0.9401). Comparable results were also shown for both groups concerning the classification of the filtering bleb, corneal staining, and numbers of treatments with 5-FU, needlings and suture lyses. More patients reported AEs in the acetazolamide/dexamethasone group than in the dorzolamide/timolol group. Discussion Preoperative, preservative-free, fixed-dose dorzolamide/timolol seems to be equally effective as preoperative acetazolamide and dexamethasone and has a favourable safety profile. PMID:28199397

  5. Analytical development of a binuclear oxo-manganese complex bio-inspired on oxidase enzyme for doping control analysis of acetazolamide.

    PubMed

    Machini, Wesley B S; Teixeira, Marcos F S

    2016-05-15

    A bio-inspired electrochemical sensor using a binuclear oxo-manganese complex was evaluated and applied in the detection of a substance associated with doping in sports: acetazolamide (ACTZ). Investigation was made of the influence of different experimental variables on the electrocatalytic oxidation of ACTZ by the bio-inspired sensor, such as pH and interfering species. The bio-inspired sensor showed the best response in the range from 5.00×10(-9) to 7.00×10(-8) mol L(-1) ACTZ, with a linear range from 5.00×10(-9) to 2.50×10(-8) mol L(-1) and a detection limit of 4.76×10(-9) mol L(-1). The sensor exhibited characteristics similar to the Michaelis-Menten model of an enzymatic electrode, due to the use of a multinucleated complex of manganese with μ-oxo units, which was able to mimic the properties of enzymes with manganese as a cofactor in their composition, such as Mn-containing oxidase. The determination of ACTZ with the bio-inspired sensor was evaluated using three different synthetic biological fluids (plasma, saliva, and urine), demonstrating its viability for use with real samples. The analysis of ACTZ in real urine samples using the bio-inspired sensor, simulating the method adopted by the World Anti-Doping Agency, which revealed viable, suggesting a new and promising platform to be used in these analysis.

  6. S···O chalcogen bonding in sulfa drugs: insights from multipole charge density and X-ray wavefunction of acetazolamide.

    PubMed

    Thomas, Sajesh P; Jayatilaka, Dylan; Guru Row, T N

    2015-10-14

    Experimental charge density analysis combined with the quantum crystallographic technique of X-ray wavefunction refinement (XWR) provides quantitative insights into the intra- and intermolecular interactions formed by acetazolamide, a diuretic drug. Firstly, the analysis of charge density topology at the intermolecular level shows the presence of exceptionally strong interaction motifs such as a DDAA-AADD (D-donor, A-acceptor) type quadruple hydrogen bond motif and a sulfonamide dimer synthon. The nature and strength of intra-molecular S···O chalcogen bonding have been characterized using descriptors from the multipole model (MM) and XWR. Although pure geometrical criteria suggest the possibility of two intra-molecular S···O chalcogen bonded ring motifs, only one of them satisfies the "orbital geometry" so as to exhibit an interaction in terms of an electron density bond path and a bond critical point. The presence of 'σ-holes' on the sulfur atom leading to the S···O chalcogen bond has been visualized on the electrostatic potential surface and Laplacian isosurfaces close to the 'reactive surface'. The electron localizability indicator (ELI) and Roby bond orders derived from the 'experimental wave function' provide insights into the nature of S···O chalcogen bonding.

  7. Does Preoperative Measurement of Cerebral Blood Flow with Acetazolamide Challenge in Addition to Preoperative Measurement of Cerebral Blood Flow at the Resting State Increase the Predictive Accuracy of Development of Cerebral Hyperperfusion after Carotid Endarterectomy? Results from 500 Cases with Brain Perfusion Single-photon Emission Computed Tomography Study

    PubMed Central

    OSHIDA, Sotaro; OGASAWARA, Kuniaki; SAURA, Hiroaki; YOSHIDA, Koji; FUJIWARA, Shunro; KOJIMA, Daigo; KOBAYASHI, Masakazu; YOSHIDA, Kenji; KUBO, Yoshitaka; OGAWA, Akira

    2015-01-01

    The purpose of the present study was to determine whether preoperative measurement of cerebral blood flow (CBF) with acetazolamide in addition to preoperative measurement of CBF at the resting state increases the predictive accuracy of development of cerebral hyperperfusion after carotid endarterectomy (CEA). CBF at the resting state and cerebrovascular reactivity (CVR) to acetazolamide were quantitatively assessed using N-isopropyl-p-[123I]-iodoamphetamine (IMP)-autoradiography method with single-photon emission computed tomography (SPECT) before CEA in 500 patients with ipsilateral internal carotid artery stenosis (≥ 70%). CBF measurement using 123I-IMP SPECT was also performed immediately and 3 days after CEA. A region of interest (ROI) was automatically placed in the middle cerebral artery territory in the affected cerebral hemisphere using a three-dimensional stereotactic ROI template. Preoperative decreases in CBF at the resting state [95% confidence intervals (CIs), 0.855 to 0.967; P = 0.0023] and preoperative decreases in CVR to acetazolamide (95% CIs, 0.844 to 0.912; P < 0.0001) were significant independent predictors of post-CEA hyperperfusion. The area under the receiver operating characteristic curve for prediction of the development of post-CEA hyperperfusion was significantly greater for CVR to acetazolamide than for CBF at the resting state (difference between areas, 0.173; P < 0.0001). Sensitivity, specificity, and positive- and negative-predictive values for the prediction of the development of post-CEA hyperperfusion were significantly greater for CVR to acetazolamide than for CBF at the resting state (P < 0.05, respectively). The present study demonstrated that preoperative measurement of CBF with acetazolamide in addition to preoperative measurement of CBF at the resting state increases the predictive accuracy of the development of post-CEA hyperperfusion. PMID:25746308

  8. Does preoperative measurement of cerebral blood flow with acetazolamide challenge in addition to preoperative measurement of cerebral blood flow at the resting state increase the predictive accuracy of development of cerebral hyperperfusion after carotid endarterectomy? Results from 500 cases with brain perfusion single-photon emission computed tomography study.

    PubMed

    Oshida, Sotaro; Ogasawara, Kuniaki; Saura, Hiroaki; Yoshida, Koji; Fujiwara, Shunro; Kojima, Daigo; Kobayashi, Masakazu; Yoshida, Kenji; Kubo, Yoshitaka; Ogawa, Akira

    2015-01-01

    The purpose of the present study was to determine whether preoperative measurement of cerebral blood flow (CBF) with acetazolamide in addition to preoperative measurement of CBF at the resting state increases the predictive accuracy of development of cerebral hyperperfusion after carotid endarterectomy (CEA). CBF at the resting state and cerebrovascular reactivity (CVR) to acetazolamide were quantitatively assessed using N-isopropyl-p-[(123)I]-iodoamphetamine (IMP)-autoradiography method with single-photon emission computed tomography (SPECT) before CEA in 500 patients with ipsilateral internal carotid artery stenosis (≥ 70%). CBF measurement using (123)I-IMP SPECT was also performed immediately and 3 days after CEA. A region of interest (ROI) was automatically placed in the middle cerebral artery territory in the affected cerebral hemisphere using a three-dimensional stereotactic ROI template. Preoperative decreases in CBF at the resting state [95% confidence intervals (CIs), 0.855 to 0.967; P = 0.0023] and preoperative decreases in CVR to acetazolamide (95% CIs, 0.844 to 0.912; P < 0.0001) were significant independent predictors of post-CEA hyperperfusion. The area under the receiver operating characteristic curve for prediction of the development of post-CEA hyperperfusion was significantly greater for CVR to acetazolamide than for CBF at the resting state (difference between areas, 0.173; P < 0.0001). Sensitivity, specificity, and positive- and negative-predictive values for the prediction of the development of post-CEA hyperperfusion were significantly greater for CVR to acetazolamide than for CBF at the resting state (P < 0.05, respectively). The present study demonstrated that preoperative measurement of CBF with acetazolamide in addition to preoperative measurement of CBF at the resting state increases the predictive accuracy of the development of post-CEA hyperperfusion.

  9. Expression, purification, kinetic, and structural characterization of an alpha-class carbonic anhydrase from Aedes aegypti (AaCA1).

    PubMed

    Fisher, S Zoë; Tariku, Iyerus; Case, Nicolette M; Tu, Chingkuang; Seron, Teri; Silverman, David N; Linser, Paul J; McKenna, Robert

    2006-08-01

    Carbonic anhydrases (CAs) are zinc-containing metalloenzymes that catalyze the interconversion of carbon dioxide and bicarbonate. The alpha-class CAs are found predominantly in vertebrates, but they are also expressed in insects like mosquitoes. Recently, an alpha-CA from the midgut of Aedes aegypti larvae (AaCA1) was identified, cloned, and subsequently shown to share high sequence homologous to human CA I (HCA I). This paper presents the bacterial expression, purification, and kinetic characterization of the soluble CA domain of AaCA1. The data show AaCA1 is a highly active CA that displays inhibition by methazolamide and ethoxzolamide with nM affinity. Additionally, a homology model of AaCA1, based on the crystal structure of HCA I, is presented and the overall structure, active site, and surface charge properties are compared to those of HCA I and II. Measurements of catalysis show that AaCA1 is more like HCA II in terms of proton transfer, but more similar to HCA I in terms of conversion of carbon dioxide to bicarbonate, and these differences are rationalized in terms of structure. These results also indicate that amino acid differences in the active site of AaCA1 compared to human CAs could be used to design specific CA inhibitors for the management of mosquito populations.

  10. Acetazolamide Mitigates Astrocyte Cellular Edema Following Mild Traumatic Brain Injury

    NASA Astrophysics Data System (ADS)

    Sturdivant, Nasya M.; Smith, Sean G.; Ali, Syed F.; Wolchok, Jeffrey C.; Balachandran, Kartik

    2016-09-01

    Non-penetrating or mild traumatic brain injury (mTBI) is commonly experienced in accidents, the battlefield and in full-contact sports. Astrocyte cellular edema is one of the major factors that leads to high morbidity post-mTBI. Various studies have reported an upregulation of aquaporin-4 (AQP4), a water channel protein, following brain injury. AZA is an antiepileptic drug that has been shown to inhibit AQP4 expression and in this study we investigate the drug as a therapeutic to mitigate the extent of mTBI induced cellular edema. We hypothesized that mTBI-mediated astrocyte dysfunction, initiated by increased intracellular volume, could be reduced when treated with AZA. We tested our hypothesis in a three-dimensional in vitro astrocyte model of mTBI. Samples were subject to no stretch (control) or one high-speed stretch (mTBI) injury. AQP4 expression was significantly increased 24 hours after mTBI. mTBI resulted in a significant increase in the cell swelling within 30 min of mTBI, which was significantly reduced in the presence of AZA. Cell death and expression of S100B was significantly reduced when AZA was added shortly before mTBI stretch. Overall, our data point to occurrence of astrocyte swelling immediately following mTBI, and AZA as a promising treatment to mitigate downstream cellular mortality.

  11. Acetazolamide Mitigates Astrocyte Cellular Edema Following Mild Traumatic Brain Injury

    PubMed Central

    Sturdivant, Nasya M.; Smith, Sean G.; Ali, Syed F.; Wolchok, Jeffrey C.; Balachandran, Kartik

    2016-01-01

    Non-penetrating or mild traumatic brain injury (mTBI) is commonly experienced in accidents, the battlefield and in full-contact sports. Astrocyte cellular edema is one of the major factors that leads to high morbidity post-mTBI. Various studies have reported an upregulation of aquaporin-4 (AQP4), a water channel protein, following brain injury. AZA is an antiepileptic drug that has been shown to inhibit AQP4 expression and in this study we investigate the drug as a therapeutic to mitigate the extent of mTBI induced cellular edema. We hypothesized that mTBI-mediated astrocyte dysfunction, initiated by increased intracellular volume, could be reduced when treated with AZA. We tested our hypothesis in a three-dimensional in vitro astrocyte model of mTBI. Samples were subject to no stretch (control) or one high-speed stretch (mTBI) injury. AQP4 expression was significantly increased 24 hours after mTBI. mTBI resulted in a significant increase in the cell swelling within 30 min of mTBI, which was significantly reduced in the presence of AZA. Cell death and expression of S100B was significantly reduced when AZA was added shortly before mTBI stretch. Overall, our data point to occurrence of astrocyte swelling immediately following mTBI, and AZA as a promising treatment to mitigate downstream cellular mortality. PMID:27623738

  12. Structural Basis for the Inhibition of Helicobacter pylori α-Carbonic Anhydrase by Sulfonamides

    PubMed Central

    Modakh, Joyanta K.; Liu, Yu C.; Machuca, Mayra A.; Supuran, Claudiu T.; Roujeinikova, Anna

    2015-01-01

    Periplasmic α-carbonic anhydrase of Helicobacter pylori (HpαCA), an oncogenic bacterium in the human stomach, is essential for its acclimation to low pH. It catalyses the conversion of carbon dioxide to bicarbonate using Zn(II) as the cofactor. In H. pylori, Neisseria spp., Brucella suis and Streptococcus pneumoniae this enzyme is the target for sulfonamide antibacterial agents. We present structural analysis correlated with inhibition data, on the complexes of HpαCA with two pharmacological inhibitors of human carbonic anhydrases, acetazolamide and methazolamide. This analysis reveals that two sulfonamide oxygen atoms of the inhibitors are positioned proximal to the putative location of the oxygens of the CO2 substrate in the Michaelis complex, whilst the zinc-coordinating sulfonamide nitrogen occupies the position of the catalytic water molecule. The structures are consistent with acetazolamide acting as site-directed, nanomolar inhibitors of the enzyme by mimicking its reaction transition state. Additionally, inhibitor binding provides insights into the channel for substrate entry and product exit. This analysis has implications for the structure-based design of inhibitors of bacterial carbonic anhydrases. PMID:26010545

  13. Toxicity and Physiological Actions of Carbonic Anhydrase Inhibitors to Aedes aegypti and Drosophila melanogaster

    PubMed Central

    Francis, Sheena A. M.; Taylor-Wells, Jennina; Gross, Aaron D.; Bloomquist, Jeffrey R.

    2016-01-01

    The physiological role of carbonic anhydrases in pH and ion regulation is crucial to insect survival. We examined the toxic and neurophysiological effects of five carbonic anhydrase inhibitors (CAIs) against Aedes aegypti. The 24 h larvicidal toxicities followed this rank order of potency: dichlorphenamide > methazolamide > acetazolamide = brinzolamide = dorzolamide. Larvicidal activity increased modestly in longer exposures, and affected larvae showed attenuated responses to probing without overt tremors, hyperexcitation, or convulsions. Acetazolamide and dichlorphenamide were toxic to adults when applied topically, but were of low potency and had an incomplete effect (<50% at 300 ng/mosquito) even after injection. Dichlorphenamide was also the most toxic compound when fed to adult mosquitoes, and they displayed loss of posture and occasionally prolonged fluttering of the wings. Co-exposure with 500 ng of the synergist piperonyl butoxide (PBO) increased the toxicity of dichlorphenamide ca. two-fold in feeding assays, indicating that low toxicity was not related to oxidative metabolism. Dichlorphenamide showed mild depolarizing and nerve discharge actions on insect neuromuscular and central nervous systems, respectively. These effects were increased in low buffer salines, indicating they were apparently related to loss of pH control in these tissues. Overall, sulfonamides displayed weak insecticidal properties on Aedes aegypti and are weak lead compounds. PMID:28025488

  14. Nrf2 activation: a potential strategy for the prevention of acute mountain sickness.

    PubMed

    Lisk, Christina; McCord, Joe; Bose, Swapan; Sullivan, Tim; Loomis, Zoe; Nozik-Grayck, Eva; Schroeder, Thies; Hamilton, Karyn; Irwin, David C

    2013-10-01

    Reactive oxygen species (ROS) formed during acute high altitude exposure contribute to cerebral vascular leak and development of acute mountain sickness (AMS). Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) is a transcription factor that regulates expression of greater than 90% of antioxidant genes, but prophylactic treatment with Nrf2 activators has not yet been tested as an AMS therapy. We hypothesized that prophylactic activation of the antioxidant genome with Nrf2 activators would attenuate high-altitude-induced ROS formation and cerebral vascular leak and that some drugs currently used to treat AMS symptoms have an additional trait of Nrf2 activation. Drugs commonly used to treat AMS were screened with a luciferase reporter cell system for their effectiveness to activate Nrf2, as well as being tested for their ability to decrease high altitude cerebral vascular leak in vivo. Compounds that showed favorable results for Nrf2 activation from our screen and attenuated high altitude cerebral vascular leak in vivo were further tested in brain microvascular endothelial cells (BMECs) to determine if they attenuated hypoxia-induced ROS production and monolayer permeability. Of nine drugs tested, with the exception of dexamethasone, only drugs that showed the ability to activate Nrf2 (Protandim, methazolamide, nifedipine, amlodipine, ambrisentan, and sitaxentan) decreased high-altitude-induced cerebral vascular leak in vivo. In vitro, Nrf2 activation in BMECs before 24h hypoxia exposure attenuated hypoxic-induced hydrogen peroxide production and permeability. Prophylactic Nrf2 activation is effective at reducing brain vascular leak from acute high altitude exposures. Compared to acetazolamide, methazolamide may offer better protection against AMS. Nifedipine, in addition to its known vasodilatory activities in the lung and protection against high altitude pulmonary edema, may provide protection against brain vascular leak as well.

  15. Nrf2 Activation: A potential strategy for the prevention of Acute Mountain Sickness

    PubMed Central

    Lisk, Christina; McCord, Joe; Bose, Swapan; Sullivan, Tim; Loomis, Zoe; Nozik-Grayck, Eva; Schroeder, Thies; Hamilton, Karyn; Irwin, David C.

    2014-01-01

    Introduction Reactive oxygen species (ROS) formed during acute high altitude exposure contributes to cerebral vascular leak and development of acute mountain sickness (AMS). Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2) is a transcription factor that regulates expression of greater than 90% of antioxidant genes, but prophylactic treatment with Nrf2 activators has not yet been tested as an AMS therapy. We hypothesized that prophylactic activation of the antioxidant genome with Nrf2 activators would attenuate high altitude-induced ROS formation and cerebral vascular leak, and that some drugs currently used to treat AMS symptoms have an additional trait of Nrf2 activation. Methods Drugs commonly used to treat AMS were screened with a luciferase reporter cell system for their effectiveness to activate Nrf2, as well as tested for their ability to decrease high altitude cerebral vascular leak in vivo. Compounds that showed favorable results for Nrf2 activation from our screen and attenuated high altitude cerebral vascular leak in vivo were further tested in brain microvascular endothelial cells (BMEC) to determine if they attenuated hypoxia-induced ROS production and monolayer permeability. Results Of 9 drugs tested, with the exception of dexamethasone, only drugs that showed the ability to activate Nrf2 (Protandim, methazolamide, nifedipine, amlodipine, ambrisentan, and sitaxentan) decreased high altitude-induced cerebral vascular leak in vivo. In vitro, Nrf2 activation in BMEC prior to 24 h hypoxia exposure attenuated hypoxic-induced hydrogen peroxide production and permeability. Conclusions Prophylactic Nrf2 activation is effective at reducing brain vascular leak from acute high altitude exposures. Compared to acetazolamide, methazolamide may offer better protection against AMS. Nifedipine, in addition to its known vasodilatory activities in the lung and protection against high altitude pulmonary edema, may provide protection against brain vascular leak

  16. [Reduction of omalgia in laparoscopic cholecystectomy: clinical randomized trial ketorolac vs ketorolac and acetazolamide].

    PubMed

    Figueroa-Balderas, Lorena; Franco-López, Francisco; Flores-Álvarez, Efrén; López-Rodríguez, Jorge Luis; Vázquez-García, José Antonio; Barba-Valadez, Claudia Teresa

    2013-01-01

    Antecedentes: la colecistectomía laparoscópica es el patrón de referencia del tratamiento de la colelitiasis sintomática. El 63% de los pacientes operados sufre dolor postquirúrgico referido al hombro (omalgia), circunstancia que limita el tratamiento ambulatorio. Objetivo: evaluar la utilidad de la acetazolamida asociada con ketorolaco para disminuir la omalgia consecutiva al tratamiento de mínima invasión. Material y métodos: ensayo clínico, aleatorizado, doble ciego realizado en pacientes a quienes se efectuó colecistectomía laparoscópica para evaluar la reducción de la omalgia postoperatoria y comparar el efecto de ketorolaco y ketorolaco más acetazolamida. En cada grupo se estudiaron 31 pacientes. El grupo de estudio recibió 250 mg de acetazolamida antes de la inducción anestésica, y 30 mg de ketorolaco en el postoperatorio inmediato. El grupo control recibió una tableta de placebo antes de la inducción anestésica, y 30 mg de ketorolaco en el postoperatorio inmediato. La omalgia se evaluó con la escala visual análoga. Las variables estudiadas incluyeron: edad, sexo, flujo de dióxido de carbono, presión intrabdominal, tiempo quirúrgico, cirugía electiva o urgente, omalgia, intensidad del dolor evaluada con la escala visual análoga y analgesia de rescate. Resultados: los grupos estudiados fueron homogéneos, el análisis estadístico no mostró diferencias en las variables estudiadas. En el grupo de estudio la omalgia coexistió en 9.67% de los pacientes y en el grupo control en 58.06% (p < 0.001). Conclusión: la administración por vía oral de 250 mg de acetazolamida y 30 mg de ketorolaco redujo significativamente la omalgia en los pacientes a quienes se realizó colecistectomía laparoscópica.

  17. CO2-stimulated NaCl absorption in the mouse renal cortical thick ascending limb of Henle. Evidence for synchronous Na +/H+ and Cl-/HCO3- exchange in apical plasma membranes

    PubMed Central

    1982-01-01

    These experiments evaluated salt transport processes in isolated cortical thick limbs of Henle (cTALH) obtained from mouse kidney. When the external solutions consisted of Krebs-Ringer bicarbonate (KRB), pH 7.4, and a 95% O2-5% CO2 gas phase, the spontaneous transepithelial voltage (Ve, mV, lumen-to-bath) was approximately mV; the net rate of Cl- absorption (JnetCl) was approximately 3,600 pmols s-1 cm-2; the net rate of osmotic solute absorption Jnetosm was twice JnetCl; and the net rate of total CO2 transport (JnetCO2) was indistinguishable from zero. Thus, net Cl- absorption was accompanied by the net absorption of a monovalent cation, presumably Na+, and net HCO3- absorption was negligible. This salt transport process was stimulated by (CO2 + HCO3- ): omission of CO2 from the gas phase and HCO3- from external solutions reduced JnetCl, Jnetosm, and Ve by 50%. Furthermore, 10(-4) M luminal furosemide abolished JnetCl and Ve entirely. The lipophilic carbonic anhydrase inhibitor ethoxzolamide (10(-4) M, either luminal or peritubular) inhibited (CO2 + HCO3-)-stimulated JnetCl, Jnetosm, and Ve by approximately 50%; however, when the combination (CO2 + HCO3-) was absent, ethoxzolamide had no detectable effect on salt transport. Ve was reduced or abolished entirely by omission of either Na+ or Cl- from external solutions, by peritubular K+ removal, by 10(-3) M peritubular ouabain, and by 10(-4) M luminal SITS. However, Ve was unaffected by 10(-3) M peritubular SITS, or by the hydrophilic carbonic anhydrase inhibitor acetazolamide (2.2 x 10(-4) M, lumen plus bath). We interpret these data to indicate that (CO2 + HCO3-)-stimulated NaCl absorption in the cTALH involved two synchronous apical membrane antiport processes: one exchanging luminal Na+ for cellular H+; and the other exchanging luminal Cl- for cellular HCO3- or OH-, operating in parallel with a (CO2+ HCO3-)-independent apical membrane NaCl cotransport mechanism. PMID:6816900

  18. CO(2)/H(+) chemoreception in the cat pre-Bötzinger complex in vivo.

    PubMed

    Solomon, I C; Edelman, N H; O'Neal, M H

    2000-06-01

    We examined the effects of focal tissue acidosis in the pre-Bötzinger complex (pre-BötC; the proposed locus of respiratory rhythm generation) on phrenic nerve discharge in chloralose-anesthetized, vagotomized, paralyzed, mechanically ventilated cats. Focal tissue acidosis was produced by unilateral microinjection of 10-20 nl of the carbonic anhydrase inhibitors acetazolamide (AZ; 50 microM) or methazolamide (MZ; 50 microM). Microinjection of AZ and MZ into 14 sites in the pre-BötC reversibly increased the peak amplitude of integrated phrenic nerve discharge and, in some sites, produced augmented bursts (i.e., eupneic breath ending with a high-amplitude, short-duration burst). Microinjection of AZ and MZ into this region also reversibly increased the frequency of eupneic phrenic bursts in seven sites and produced premature bursts (i.e., doublets) in five sites. Phrenic nerve discharge increased within 5-15 min of microinjection of either agent; however, the time to the peak increase and the time to recovery were less with AZ than with MZ, consistent with the different pharmacological properties of AZ and MZ. In contrast to other CO(2)/H(+) brain stem respiratory chemosensitive sites demonstrated in vivo, which have only shown increases in amplitude of integrated phrenic nerve activity, focal tissue acidosis in the pre-BötC increases frequency of phrenic bursts and produces premature (i.e., doublet) bursts. These data indicate that the pre-BötC has the potential to play a role in the modulation of respiratory rhythm and pattern elicited by increased CO(2)/H(+) and lend additional support to the concept that the proposed locus for respiratory rhythm generation has intrinsic chemosensitivity.

  19. Energization of sodium absorption by the H(+)-ATPase pump in mitochondria-rich cells of frog skin.

    PubMed

    Harvey, B J

    1992-11-01

    The frog skin in vivo is capable of active transepithelial H+ secretion (JH) which is matched by Na+ absorption (JNa). Studies in vitro demonstrate that JH is generated by an H(+)-ATPase pump localized in apical membranes of mitochondria-rich (MR) cells, whereas JNa occurs through an amiloride-sensitive pathway in principal (P) cells. The H+ pump is sensitive to inhibitors of carbonic anhydrase (e.g. acetazolamide) and to specific inhibitors of mitochondrial F1F0 H(+)-ATPase (oligomycin) and vacuolar (V)-type H(+)-ATPase (N-ethylmaleimide) and to inhibitors of both these types of H(+)-ATPases (dicyclohexylcarbodiimide, DCCD). JH is independent of external K+, which differentiates it from gastric H+/K(+)-ATPase and is strictly dependent on aerobic metabolism. The proton pump is primarily implicated in whole-body acid-base regulation. Acute stimulation of JH in response (seconds-minutes) to an acid load involves insertion of H+ pumps (exocytosis) from a cytosolic pool into the apical membrane. The chronic response (days) to metabolic acid load involves morphological changes (increased apical membrane surface area and number of MR cells). Whole-cell patch-clamp recordings of membrane capacitance and current fluctuations from MR cells demonstrate that a respiratory acid load and aldosterone produce rapid exocytotic insertion of DCCD-sensitive conductive membrane. A secondary role of the H+ pump is to energize sodium absorption (JNa) via principal cells from dilute solutions in the absence of a permeant anion under open-circuit conditions. The apparent 1:1 stoichiometry between JH and JNa is a result of transepithelial electrical coupling between these electrogenic fluxes. The H+ pump in MR cells generates a transepithelial current (serosa to apical) which acts as a physiological voltage-clamp to hyperpolarize the apical membrane of P cells. This hyperpolarization can facilitate passive Na+ entry across the apical membrane against a threefold chemical gradient. Since

  20. On the lack of specificity of the cobalt-bicarbonate method for carbonic anhydrase.

    PubMed

    Muther, T F

    1977-09-01

    Data are presented that support a nonenzymic mechanism for the staining obtained with the cobalt-bicarbonate method. The biochemically inactive apocarbonic anhydrase and Cu+2 apocarbonic anhydrase stain positively and this stain is inhibited by acetazolamide. The staining of the acetazolamide resistant carbonic anhydrase of male rat liver is inhibited by 10-6 M acetazolamide, at which concentration no biochemical inhibition is observed. There is no correlation between the biochemical and histochemical inhibitory potencies of a number of sulfonamides. The nonsulfonamide inhibitor, KCNO, does not inhibit staining. When incubations are performed in media exposed to atmospheres of increasing CO2 content, staining is not abolished until the atmospheric pCO2 approaches that generated by the medium itself. This finding renders the carbonic anhydrase catalyzed dehydration of HCO3- an improbable reaction for the staining. Studies with modified media show differences in staining patterns and in sensitivity to acetazolamide inhibition which question the specificity of the method for carbonic anhydrase.

  1. Inhibition of Alkaline Phosphatase by Several Diuretics

    DTIC Science & Technology

    1980-01-01

    August 20th, 1979) . . Summary , . Acetazolamide, furosemide, ethacrynic acid and chlorothiazide, diuretics of considerable structural diversity, inhibit...Ki is calculated to be 8.4, 7.0, 2.8 and 0.1 mmol/l for acetazolamide, furosemide, ethacrynic acid and chlorothiazide, respectively. Chlorothiazide...is a much more potent inhibitor of alkaline phos- phatase than the other three diuretics. The combination of ethacrynic acid and cysteine, itself an

  2. Carbonic anhydrase and chemoreception in the cat carotid body.

    PubMed

    Iturriaga, R; Lahiri, S; Mokashi, A

    1991-10-01

    To test the hypothesis that CO2 and O2 chemoreception in the carotid body (CB) may depend on its carbonic anhydrase (CA) activity, we used an in vitro cat CB preparation and studied the effects of methazolamide, a permeable CA inhibitor (pK 7.3), on the chemosensory responses to CO2, O2, and nicotine. The isolated CB was perfused and superfused with Tyrode solution, free of CO2-HCO3-, at 36.0 +/- 0.5 degrees C. The frequency of chemosensory discharges was recorded from the whole carotid sinus nerve. The responses to bolus injections (0.3-0.5 ml) of Tyrode solution equilibrated with PCO2 of 38-110 Torr, switching from HEPES to CO2-HCO3- Tyrode (PCO2 = 25-60 Torr) for about 3 min, hypoxic Tyrode (PO2 = 25-30 Torr) for 2-8 min, perfusate flow interruptions for approximately 4 min, and bolus injections of nicotine (4 nmol) were studied before, during, and after perfusion (30-45 min) with methazolamide (42.4 microM). Methazolamide reversibly inhibited, delayed, and reduced the responses to transient CO2 stimulus, diminished the onset of but not the late response to prolonged CO2 stimulus, and delayed but did not decrease the responses to hypoxia and perfusate interruption. The response to nicotine did not change. The results indicated that CA in the glomus cells played a crucial role primarily in the speed and magnitude of the initial response to CO2 stimulus and indirectly influenced O2 chemoreception. These effects were upstream from the nicotine receptor-mediated sensory response.

  3. Testing the limits of sensitivity in a solid-state structural investigation by combined X-ray powder diffraction, solid-state NMR, and molecular modelling.

    PubMed

    Filip, Xenia; Borodi, Gheorghe; Filip, Claudiu

    2011-10-28

    A solid state structural investigation of ethoxzolamide is performed on microcrystalline powder by using a multi-technique approach that combines X-ray powder diffraction (XRPD) data analysis based on direct space methods with information from (13)C((15)N) solid-state Nuclear Magnetic Resonance (SS-NMR) and molecular modeling. Quantum chemical computations of the crystal were employed for geometry optimization and chemical shift calculations based on the Gauge Including Projector Augmented-Wave (GIPAW) method, whereas a systematic search in the conformational space was performed on the isolated molecule using a molecular mechanics (MM) approach. The applied methodology proved useful for: (i) removing ambiguities in the XRPD crystal structure determination process and further refining the derived structure solutions, and (ii) getting important insights into the relationship between the complex network of non-covalent interactions and the induced supra-molecular architectures/crystal packing patterns. It was found that ethoxzolamide provides an ideal case study for testing the accuracy with which this methodology allows to distinguish between various structural features emerging from the analysis of the powder diffraction data.

  4. Anion exchanger and chloride channel in cat carotid body chemotransduction.

    PubMed

    Iturriaga, R; Mokashi, A; Lahiri, S

    1998-05-28

    In order to test the hypothesis that carotid body (CB) chemoreception depends on the functions of anion channels and HCO3-/Cl- exchangers, we studied the effects of the anion channel blocker anthracene-9-carboxylic acid (9-ANC), the carbonic anhydrase inhibitor methazolamide, and the HCO3-/Cl- exchanger blocker 4,4 diisothiocyanatostilbene-2-2'disulfonic acid (DIDS) on the chemosensory discharges of cat CB, perfused-superfused in vitro at 36.5 +/- 0.5 degrees C, with a modified Tyrode solution. The chemosensory responses to hypoxia (PO2 approximately 50 Torr), hypercapnia (PCO2 approximately 60 Torr, pH = 7.10), nicotine (2-4 nmol) and NaCN (20-40 nmol) were recorded. 9-ANC (2 microM) and DIDS (10 microM) decreased the chemosensory baseline activity, and eliminated the initial peak responses to hypercapnia and hypoxia and increased the time to achieve it. Methazolamide (0.13 mM) did not alter the effect of 9-ANC. The steady state responses to hypoxia and hypercapnia were not diminished after 9-ANC but DIDS lowered the responses. Responses to NaCN effects were all diminished but those to nicotine were not affected. The results suggest that the functions of anion channels and HCO3-/Cl- exchangers are important for the resting dischargers and for the fast responses to hypoxia and hypercapnia.

  5. Evaluation of the therapeutic potential of carbonic anhydrase inhibitors in two animal models of dystrophin deficient muscular dystrophy.

    PubMed

    Giacomotto, Jean; Pertl, Cordula; Borrel, Caroline; Walter, Maggie C; Bulst, Stefanie; Johnsen, Bob; Baillie, David L; Lochmüller, Hanns; Thirion, Christian; Ségalat, Laurent

    2009-11-01

    Duchenne Muscular Dystrophy is an inherited muscle degeneration disease for which there is still no efficient treatment. However, compounds active on the disease may already exist among approved drugs but are difficult to identify in the absence of cellular models. We used the Caenorhabditis elegans animal model to screen a collection of 1000 already approved compounds. Two of the most active hits obtained were methazolamide and dichlorphenamide, carbonic anhydrase inhibitors widely used in human therapy. In C. elegans, these drugs were shown to interact with CAH-4, a putative carbonic anhydrase. The therapeutic efficacy of these compounds was further validated in long-term experiments on mdx mice, the mouse model of Duchenne Muscular Dystrophy. Mice were treated for 120 days with food containing methazolamide or dichlorphenamide at two doses each. Musculus tibialis anterior and diaphragm muscles were histologically analyzed and isometric muscle force was measured in M. extensor digitorum longus. Both substances increased the tetanic muscle force in the treated M. extensor digitorum longus muscle group, dichlorphenamide increased the force significantly by 30%, but both drugs failed to increase resistance of muscle fibres to eccentric contractions. Histological analysis revealed a reduction of centrally nucleated fibers in M. tibialis anterior and diaphragm in the treated groups. These studies further demonstrated that a C. elegans-based screen coupled with a mouse model validation strategy can lead to the identification of potential pharmacological agents for rare diseases.

  6. A class of sulfonamide carbonic anhydrase inhibitors with neuropathic pain modulating effects.

    PubMed

    Carta, Fabrizio; Di Cesare Mannelli, Lorenzo; Pinard, Melissa; Ghelardini, Carla; Scozzafava, Andrea; McKenna, Robert; Supuran, Claudiu T

    2015-04-15

    A series of benzene sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors which incorporate lipophilic 4-alkoxy- and 4-aryloxy moieties, together with several derivatives of ethoxzolamide and sulfanilamide are reported. These derivatives were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) of which multiple isoforms are known, and some appear to be involved in pain. These sulfonamides showed modest inhibition against the cytosolic isoform CA I, but were generally effective, low nanomolar CA II, VII, IX and XII inhibitors. X-ray crystallographic data for the adduct of several such sulfonamides with CA II allowed us to rationalize the good inhibition data. In a mice model of neuropathic pain induced by oxaliplatin, one of the strong CA II/VII inhibitors reported here induced a long lasting pain relieving effect, a fact never observed earlier. This is the first report of rationally designed sulfonamide CA inhibitors with pain effective modulating effects.

  7. Acute therapeutic modalities for experimental vasogenic edema.

    PubMed

    Harbaugh, R D; James, H E; Marshall, L F; Shapiro, H M; Laurin, R

    1979-12-01

    Experimental vasogenic cerebral edema was created in rabbits with a cold-induced left occipital cortical lesions. Intracranial pressure (ICP), intracranial elastance (Em), water content, hemispheric brain tissue volume, electrolytes, electroencephalograms, behavior, and gross pathology were studied. Various therapeutic modalities were employed alone or in combination to reduce ICP acutely: acetazolamide, furosemide, mannitol, pentobarbital, lorazepam, and dexamethasone. All therapies except dexamethasone were effective in reducing ICP. Peak ICP reduction occurred at 27 +/- 9.8 (SD) minutes with mannitol and at 71.4 +/- 15.5 minutes with acetazolamide, with the remaining agents and combinations falling between these two extreme values. Em improved by 31.7 +/- 17.02% in all therapuetic trials except those employing acetazolamide and lorazepam. With therapy, there was a reduction in the water content of the hemispheres, but the difference from that in the untreated, lesioned animals was not statistically significant. In the lesioned left hemisphere, sodium content was increased by acetazolamide (p less than 0.005), furosemide (p less than 0.025), pentobarbital (p less than 0.05), and the combination of dexamethasone, pentobarbital, and mannitol (p less than 0.005). Significant reduction was noted in the lesioned group for the potassium content of the left hemisphere in the dexamethasone (p less than 0.05), pentobarbital (p less than 0.025), and combination groups containing these agents (p less than 0.005 to 0.025). (Neurosurgery, 5: 656--665, 1979).

  8. Altitude Preexposure Recommendations for Inducing Acclimatization

    DTIC Science & Technology

    2010-01-01

    acetazolamide ( Kronenberg and Cain, 1968). Acute exposure to high altitude increases heart rate and cardiac output to maintain systemic oxygen delivery...emphasizing the regulation of breathing. Physiologist. 11:37–57. Kronenberg R.S., and Cain S.M. (1968). Hastening respiratory acclimatization to

  9. Multiscale modelling of pharmaceutical powders: Macroscopic behaviour prediction

    NASA Astrophysics Data System (ADS)

    Loh, Jonathan; Ketterhagen, William; Elliott, James

    2013-06-01

    The pharmaceutical industry uses computer models at many stages during drug development. Quantum and molecular models are used to predict the crystal structures of potential active pharmaceutical ingredients (APIs), whereas discrete element models are used to optimise the mechanical properties of mixtures of APIs and excipient powders. The present work combines the strengths of modelling from all of the mentioned length scales to predict the behaviour of macroscopic powder granules from first principles using the molecular and crystal structures of acetazolamide as an example API. Starting with a single molecule of acetazolamide, ab initio self-consistent field calculations were used to calculate the equilibrium gas phase structure, vibrational spectra, interaction energy with water molecules and perform potential energy scans. By using these results and following the CHARMM General Force Field parameterisation process, all of the parameters required to perform a molecular dynamics simulation were iteratively determined using the CHARMM program. Next, by using crystallographic data from literature, the monoclinic and triclinic forms of the acetazolamide crystal were simulated. Material properties like the Young's modulus and Poisson ratio, and surface energies have been calculated. These material properties are then used as input parameters in a discrete element model containing Thornton's plastic model and the JKR cohesive force to predict the behaviour of macroscopic acetazolamide powder in angle of repose tests and tabletting simulations. Similar methodologies can be employed in the future to evaluate at an early stage the performance of novel APIs and excipients for tabletting applications.

  10. Carbonic anhydrase activation enhances object recognition memory in mice through phosphorylation of the extracellular signal-regulated kinase in the cortex and the hippocampus.

    PubMed

    Canto de Souza, Lucas; Provensi, Gustavo; Vullo, Daniela; Carta, Fabrizio; Scozzafava, Andrea; Costa, Alessia; Schmidt, Scheila Daiane; Passani, Maria Beatrice; Supuran, Claudiu T; Blandina, Patrizio

    2017-03-09

    Rats injected with by d-phenylalanine, a carbonic anhydrase (CA) activator, enhanced spatial learning, whereas rats given acetazolamide, a CA inhibitor, exhibited impairments of fear memory consolidation. However, the related mechanisms are unclear. We investigated if CAs are involved in a non-spatial recognition memory task assessed using the object recognition test (ORT). Systemic administration of acetazolamide to male CD1 mice caused amnesia in the ORT and reduced CA activity in brain homogenates, while treatment with d-phenylalanine enhanced memory and increased CA activity. We provided also the first evidence that d-phenylalanine administration rapidly activated extracellular signal-regulated kinase (ERK) pathways, a critical step for memory formation, in the cortex and the hippocampus, two brain areas involved in memory processing. Effects elicited by d-phenylalanine were completely blunted by co-administration of acetazolamide, but not of 1-N-(4-sulfamoylphenyl-ethyl)-2,4,6-trimethylpyridinium perchlorate ((C18),) a CA inhibitor that, differently from acetazolamide, does not cross the blood brain barrier. Our results strongly suggest that brain but not peripheral CAs activation potentiates memory as a result of ERK pathway enhanced activation.

  11. Visual Field Outcomes for the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT)

    PubMed Central

    Wall, Michael; Johnson, Chris A.; Cello, Kimberly E.; Zamba, K. D.; McDermott, Michael P.; Keltner, John L.

    2016-01-01

    Purpose The Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) showed that acetazolamide provided a modest, significant improvement in mean deviation (MD). Here, we further analyze visual field changes over the 6-month study period. Methods Of 165 subjects with mild visual loss in the IIHTT, 125 had perimetry at baseline and 6 months. We evaluated pointwise linear regression of visual sensitivity versus time to classify test locations in the worst MD (study) eye as improving or not; pointwise changes from baseline to month 6 in decibels; and clinical consensus of change from baseline to 6 months. Results The average study eye had 36 of 52 test locations with improving sensitivity over 6 months using pointwise linear regression, but differences between the acetazolamide and placebo groups were not significant. Pointwise results mostly improved in both treatment groups with the magnitude of the mean change within groups greatest and statistically significant around the blind spot and the nasal area, especially in the acetazolamide group. The consensus classification of visual field change from baseline to 6 months in the study eye yielded percentages (acetazolamide, placebo) of 7.2% and 17.5% worse, 35.1% and 31.7% with no change, and 56.1% and 50.8% improved; group differences were not statistically significant. Conclusions In the IIHTT, compared to the placebo group, the acetazolamide group had a significant pointwise improvement in visual field function, particularly in the nasal and pericecal areas; the latter is likely due to reduction in blind spot size related to improvement in papilledema. (ClinicalTrials.gov number, NCT01003639.) PMID:26934136

  12. Efficacy and harm of pharmacological prevention of acute mountain sickness: quantitative systematic review

    PubMed Central

    Dumont, Lionel; Mardirosoff, Chahé; Tramèr, Martin R

    2000-01-01

    Objective To quantify efficacy and harm of pharmacological prevention of acute mountain sickness. Data sources Systematic search (Medline, Embase, Cochrane Library, internet, bibliographies, authors) in any language, up to October 1999. Study selection Randomised placebo controlled trials. Data extraction Dichotomous data on efficacy and harm from 33 trials (523 subjects received 13 different interventions, 519 a placebo). Data synthesis At above 4000 m the mean incidence of acute mountain sickness with placebo was 67% (range 25% to 100%); incidence depended on the rate of ascent, but not on the altitude or the mode of ascent. Across all ascent rates, dexamethasone 8-16 mg prevented acute mountain sickness (relative risk 2.50 (95% confidence interval 1.71 to 3.66); number needed to treat (NNT) 2.8 (2.0 to 4.6)), without evidence of dose responsiveness. Acetazolamide 750 mg was also efficacious (2.18 (1.52 to 3.15); NNT 2.9 (2.0 to 5.2)), but 500 mg was not. In two trials, adverse reaction (including depression) occurred after dexamethasone was stopped abruptly (4.45 (1.08 to 18); NNT 3.7 (2.5 to 6.9)). With acetazolamide, paraesthesia (4.02 (1.71 to 9.43); NNT 3.0 (2.0 to 6.0)) and polyuria (4.24 (1.92 to 9.37); NNT 3.6 (2.5 to 6.2)) were reported. Data were sparse on nifedipine, frusemide (furosemide), dihydroxyaluminium-sodium, spironolactone, phenytoin, codeine, phenformin, antidiuretic hormone, and ginkgo biloba. Conclusions At above 4000 m, with a high ascent rate, fewer than three subjects need to be treated with prophylactic dexamethasone 8-16 mg or acetazolamide 750 mg for one subject not to experience acute mountain sickness who would have done so had they all received a placebo. Acetazolamide 500 mg does not work. PMID:10915127

  13. Effects of High Altitude on Neurological and Pulmonary Function: The Effect of High Altitude on Visual Evoked Potentials in Humans on Mt. Everest.

    DTIC Science & Technology

    1985-07-25

    on Mount 1. Larson EB, Roach RC, Schoene RB, et al: Acetazolamide and Rainier , which may allow more meaningful comparisons, acute mountain sickness...CDM Fort Sam Houston, TX 78234-6100 1.9 -J., 19 ’ % Phenytoin and Acute Mountain Sickness on Mount Everest RICHARD N. W. WOHNS, M.D. Twenty-one...M.S. clinical trial of phenytoin prophylaxis for acute mountain sickness ANTON KARUZA, D.P.M. during the approach to the northeast ridge of Mount

  14. Department of Clinical Investigation Annual Research Progress Report, Fiscal Year 1985,

    DTIC Science & Technology

    1985-10-01

    of Mount Rainier and to determine the effect of high dose acetazolamide on the pertormance of soldiers during a rapid ascent of Mount Rainier ...Technical Approach: Approximately 30 soliders who are making a rapid ascent of Mount Rainier as part of their training will be recruited for this study...acute mountain sickness in soldiers making a rapid ascent of Mount Rainier and to determine the ef- fect of Dilantin on the performance of soldiers

  15. AltitudeOmics: The Basic Biology of Human Acclimatization to High Altitude. Addendum

    DTIC Science & Technology

    2014-09-01

    rapid, active ascent of Mount Rainier . Aviation, space, and environmental medicine 1983;54:397-401. Larson EB, Roach RC, Schoene RB, Hornbein TF...active ascent of Mount Rainier . Aviation, space, and environmental medicine 1983;54:397-401. Larson EB, Roach RC, Schoene RB, Hornbein TF. Acute...ascent of Mount Rainier . Aviat Space Environ Med 1983;54:397-401. 47. Grissom CK, Roach RC, Sarnquist FH, Hackett PH. Acetazolamide in the treatment

  16. Effects of carbonic anhydrase inhibition on ventilation-perfusion matching in the dog lung.

    PubMed Central

    Swenson, E R; Robertson, H T; Hlastala, M P

    1993-01-01

    Lung carbonic anhydrase (CA) permits rapid pH responses when changes in regional ventilation or perfusion alter airway and alveolar PCO2. These pH changes affect airway and vascular resistances and lung compliance to optimize the balance of regional ventilation (VA) and perfusion (Q) in the lung. To test the hypothesis that these or other CA-dependent mechanisms contribute to VA/Q matching, we administered acetazolamide (25 mg/kg intravenously) to six anesthetized and paralyzed dogs and measured VA/Q relationships before and after CA inhibition by the multiple inert gas elimination technique. Four other groups of dogs were studied to control for possible confounding effects of time under anesthesia and nonselective CA inhibition by acetazolamide: (a) saline placebo as a control for duration of anesthesia, (b) 4% CO2 inhalation to mimic systemic CO2 retention, (c) 1 mg/kg benzolamide (a selective renal CA inhibitor) or 0.5 meq/kg HCl to mimic systemic metabolic acidosis, and (d) 500 mg/kg 4,4'-dinitrostilbene-2,2'-disulfonate (an inhibitor of red cell band 3 protein) to mimic the respiratory acidosis arising from an intracapillary block to rapid mobilization of plasma HCO3- in CO2 exchange. Acetazolamide increased VA/Q mismatch and reduced arterial PO2 measured at equilibrium but these did not occur in the control group. There was no deterioration in VA/Q matching when systemic respiratory acidosis produced either by CO2 inhalation or 4,4'-dinitrostilbene-2,2'-disulfonate or metabolic acidosis (benzolamide or HCl) were imposed to mimic the effects of acetazolamide apart from its inhibition of lung CA. These results support the concept that lung CA subserves VA/Q matching in the normal lung. Images PMID:8349809

  17. Cerebrospinal fluid cutaneous fistula following obstetric epidural analgaesia. Case report.

    PubMed

    Fedriani de Matos, J J; Quintero Salvago, A V; Gómez Cortés, M D

    2017-03-28

    Cutaneous fistula of cerebrospinal fluid is a rare complication of neuroaxial blockade. We report the case of a parturient in whom an epidural catheter was placed for labour analgesia and 12h after the catheter was removed, presented an abundant asymptomatic fluid leak from the puncture site, compatible in the cyto-chemical analysis with cerebrospinal fluid. She was treated with acetazolamide, compression of skin orifice of the fluid leakage, antibiotic prophylaxis, hydration and rest, and progressed satisfactorily without requiring blood patch.

  18. Diabetic ketoacidosis and acute mountain sickness: case report and review of treatment options in type 1 diabetes mellitus.

    PubMed

    Miller, Steven C M

    2015-06-01

    A 30-year-old man with a 20-year history of well-controlled type 1 diabetes mellitus and no microvascular complications traveled from near sea level to an altitude of 3000 m within 6 hours. At altitude, his blood glucose levels began to rise, necessitating increased insulin delivery. Typical symptoms of acute mountain sickness (AMS) developed, and he became increasingly hyperglycemic and unwell. Upon presentation to an emergency clinic, diabetic ketoacidosis (DKA) was diagnosed and was managed with insulin, intravenous fluids with potassium, and acetazolamide orally. No other potential causes for diabetic ketoacidosis were identified. Hyperglycemia, ketosis, and acidosis resolved with treatment as expected, but an increased insulin requirement was noted for the next 48 hours, until returning to expected levels when acetazolamide was discontinued. This case describes an episode of mild diabetic ketoacidosis potentially precipitated by moderate to severe acute mountain sickness, and an apparent hyperglycemic effect of acetazolamide. Individuals with type 1 diabetes traveling to altitude and their physicians should be vigilant for this complication and should be aware of the effects of conventional first-line therapies for acute mountain sickness on insulin requirement, glycemic control, and preexisting microvascular diabetes complications.

  19. Evidence for bicarbonate-dependent magnesium reabsorption.

    PubMed

    Hartmann, A; Langberg, H; Dibona, G; Kiil, F

    1983-01-01

    During ethacrynic acid administration about 50% of the filtered load of magnesium is reabsorbed. To examine whether the remaining component of magnesium reabsorption is bicarbonate-dependent, i.e. varies with factors known to alter passive reabsorption, experiments were performed in anesthetized dogs. During ethacrynic acid administration MgCl2 infusion raised the plasma concentration of magnesium (PMg) from 0.64 +/- 0.05 to 3.06 +/- 0.27 mM and doubled magnesium reabsorption. The infusion of acetazolamide at high PMg reduced bicarbonate reabsorption by 41 +/- 3% and magnesium reabsorption by 31 +/- 16%. When plasma pH was reduced to 7.04 +/- 0.02 and increased to 7.83 +/- 0.02 by altering PCO2 at a constant plasma bicarbonate concentration of 31.2 +/- 0.8 mM, magnesium and bicarbonate reabsorption were correlated (r = 0.82). The infusion of mannitol, which acts by reducing passive solute transport without affecting bicarbonate reabsorption, halved magnesium reabsorption. By combining mannitol and acetazolamide infusions, only 6 +/- 4% of the filtered magnesium was still reabsorbed. These results indicate that the reabsorption of magnesium remaining after the infusion of ethacrynic acid and after raising PMg varies with changes in PCO2 and is inhibited by the infusion of acetazolamide and mannitol as expected for bicarbonate-dependent passive reabsorption.

  20. Maleate-induced bicarbonaturia in the dog: a carbonic anhydrase-independene effect.

    PubMed

    Gougoux, A; Lemieux, G; Lavoie, N

    1976-10-01

    Studies were performed to characterize the renal effects of maleate in anesthetized dogs. Following the intravenous administration of maleate or maleic acid (50 mg/kg), mean fractional bicarbonate excretion (CHCO3/GFR) rose to as high as 26%. Na, K, and phosphate excretion also increased markedly, whereas C1 excretion remained low. An initial transient fall in urinary pH from 6.53 to 6.13 contrasted sharply with the rapid alkalinization of the urine induced by acetazolamide administration. During saline expansion CHCO3/GFR rose from 4 to 37% after maleate administration, whereas Cl excretion did not change significantly. During continuous carbonic anhydrase inhibition with acetazolamide, maleate administration resulted in a further rise in CHCO3/GFR from 22 to 35%. Whereas CPO4/GFR increased only from 1 to 3% during acetazolamide administration, this ratio reached 75% following the addition of maleate. Fumarate, the transisomer of maleate, and malonate, a well-known inhibitor of Krebs cycle, failed to affect bicarbonate excretion. This study demonstrates that maleate inhibits the fraction of bicarbonate reabsorption uncatalyzed by carbonic anhydrase. Impaired anionic reabsorption of bicarbonate or accelerated passive backflux of this ion into proximal tubular lumen are the two mechanisms that best explain the bicarbonaturia induced by maleate.

  1. Freeze-dried amorphous dispersions for solubility enhancement of thermosensitive API having low molecular lipophilicity.

    PubMed

    Kulthe, V V; Chaudhari, P D; Aboul-Enein, H Y

    2014-09-01

    The present study focuses on the development of an alternative 'thermally gentle' strategy such as freeze-drying to obtain not only solubility enhanced but also physically stabilised amorphous solid dispersions of acetazolamide, which melt with decomposition (M.P.~260°C). The solid dispersions were prepared by freeze-drying an aqueous dispersion of acetazolamide containing a lyoprotectant as sugar alcohol (mannitol) in 1:0.5, 1:1 and 1:2 proportions by weight. All the proportions of solid dispersions reported a marked increase in solubility characteristics compared to those of pure drug; with outstanding performance by 1:1 ratio of about 6 folds rise in saturation solubility and 90% drug release in about initial 30 minutes. This could be attributed to the formation amorphous molecular dispersions, cosolvent effect of mannitol on dispersed acetazolamide as well as its local solubilisation effect at the diffusion layer. During stability study also, 1:1 ratio of solid dispersions reported an insignificant change in solubility characteristics subjected to an unchanged amorphous nature. Such physical stability could be attributed to decreased molecular mobility of the drug molecules in amorphous carrier because of weaker drug-carrier interactions. Thus, it was demonstrated that freeze-drying is an effective method of forming dissolution-enhanced, amorphous solid dispersions of thermally degradable APIs.

  2. Incidence and Symptoms of High Altitude Illness in South Pole Workers: Antarctic Study of Altitude Physiology (ASAP)

    PubMed Central

    Anderson, Paul J.; Miller, Andrew D.; O’Malley, Kathy A.; Ceridon, Maile L.; Beck, Kenneth C.; Wood, Christina M.; Wiste, Heather J.; Mueller, Joshua J.; Johnson, Jacob B.; Johnson, Bruce D.

    2011-01-01

    Introduction: Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to altitude), cold, and immediate exertion would increase altitude illness risk. Methods: Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m2) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at altitude. Acetazolamide, while not mandatory, was used by 40% of participants. Results: At SP, the barometric pressure resulted in physiological altitudes that approached 3400 m, while T °C averaged −42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1–2, yet in >20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less altitude experience, worse symptoms on previous exposures, and less SP experience. Conclusion: The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar altitudes. Thus, the SP constitutes a more intense altitude exposure than might be expected considering physical

  3. Computational Drug Target Screening through Protein Interaction Profiles

    PubMed Central

    Vilar, Santiago; Quezada, Elías; Uriarte, Eugenio; Costanzi, Stefano; Borges, Fernanda; Viña, Dolores; Hripcsak, George

    2016-01-01

    The development of computational methods to discover novel drug-target interactions on a large scale is of great interest. We propose a new method for virtual screening based on protein interaction profile similarity to discover new targets for molecules, including existing drugs. We calculated Target Interaction Profile Fingerprints (TIPFs) based on ChEMBL database to evaluate drug similarity and generated new putative compound-target candidates from the non-intersecting targets in each pair of compounds. A set of drugs was further studied in monoamine oxidase B (MAO-B) and cyclooxygenase-1 (COX-1) enzyme through molecular docking and experimental assays. The drug ethoxzolamide and the natural compound piperlongumine, present in Piper longum L, showed hMAO-B activity with IC50 values of 25 and 65 μM respectively. Five candidates, including lapatinib, SB-202190, RO-316233, GW786460X and indirubin-3′-monoxime were tested against human COX-1. Compounds SB-202190 and RO-316233 showed a IC50 in hCOX-1 of 24 and 25 μM respectively (similar range as potent inhibitors such as diclofenac and indomethacin in the same experimental conditions). Lapatinib and indirubin-3′-monoxime showed moderate hCOX-1 activity (19.5% and 28% of enzyme inhibition at 25 μM respectively). Our modeling constitutes a multi-target predictor for large scale virtual screening with potential in lead discovery, repositioning and drug safety. PMID:27845365

  4. Cerebral blood flow and cerebrovascular reserve capacity: estimation by dynamic magnetic resonance imaging.

    PubMed

    Schreiber, W G; Gückel, F; Stritzke, P; Schmiedek, P; Schwartz, A; Brix, G

    1998-10-01

    We have developed a new method for estimation of regional CBF (rCBF) and cerebrovascular reserve capacity on a pixel-by-pixel basis by means of dynamic magnetic resonance imaging (MRI). Thirteen healthy volunteers, 8 patients with occlusion and/or high grade stenosis of the internal carotid artery (ICA), and 2 patients with acute stroke underwent dynamic susceptibility-weighted contrast enhanced MRI. Using principles of indicator dilution theory and deconvolution analysis, maps of rCBF, regional cerebral blood volume, and of the mean transit time (MTT) were calculated. In patients with ICA occlusion/stenosis, cerebrovascular reserve capacity was assessed by the rCBF increase after acetazolamide stimulation. Mean gray and white matter rCBF values in normals were 67.1 and 23.7 mL x 100 g(-1) x min(-1), respectively. Before acetazolamide stimulation, six of eight patients with ICA occlusions showed decreased rCBF values; and in seven patients increased MTT values were observed in tissue ipsilateral to the occlusion. After acetazolamide stimulation, decreased cerebrovascular reserve capacity was observed in five of eight patients with ICA occlusion. In acute stroke, rCBF in the central core of ischemia was less than 8 mL x 100 g(-1) x min(-1). In peri-infarct tissue, rCBF and MTT were higher than in unaffected tissue but rCBF was normal. Dynamic MRI provides important clinical information on the hemodynamic state of brain tissue in patients with occlusive cerebrovascular disease or acute stroke.

  5. Inhibition of carbonic anhydrase augments GABAA receptor-mediated analgesia via a spinal mechanism of action

    PubMed Central

    Asiedu, Marina N.; Mejia, Galo L.; Hübner, Christian A.; Kaila, Kai; Price, Theodore J.

    2014-01-01

    Peripheral nerve injury negatively influences spinal GABAergic networks via a reduction in the neuron-specific K+-Cl- cotransporter KCC2. This process has been linked to the emergence of neuropathic allodynia. In vivo pharmacological and modeling studies show that a loss of KCC2 function results in a decrease in the efficacy of GABAA -mediated spinal inhibition. One potential strategy to mitigate this effect entails inhibition of carbonic anhydrase activity to reduce HCO3- -dependent depolarization via GABAA receptors when KCC2 function is compromised. We have tested this hypothesis here. Our results show that, similarly to when KCC2 is pharmacologically blocked, peripheral nerve injury causes a loss of analgesic effect for neurosteroid GABAA allosteric modulators at maximally effective doses in naïve mice in the tail flick test. Remarkably, inhibition of carbonic anhydrase activity with intrathecal acetazolamide rapidly restores an analgesic effect for these compounds suggesting an important role of carbonic anhydrase activity in regulating GABAA -mediated analgesia after peripheral nerve injury. Moreover, spinal acetazolamide administration leads to a profound reduction in the mouse formalin pain test indicating that spinal carbonic anhydrase inhibition produces analgesia when primary afferent activity is driven by chemical mediators. Finally, we demonstrate that systemic administration of acetazolamide to rats with peripheral nerve injury produces an anti-allodynia effect by itself and an enhancement of the peak analgesic effect with a change in the shape of the dose response curve of the α1-sparing benzodiazepine L-838,417. Thus, carbonic anhydrase inhibition mitigates the negative effects of loss of KCC2 function after nerve injury in multiple species and through multiple administration routes resulting in an enhancement of analgesic effects for several GABAA allosteric modulators. We suggest that carbonic anhydrase inhibitors, many of which are clinically

  6. Physiological variables associated with the development of acute mountain sickness at the South Pole

    PubMed Central

    Harrison, Michael F; Anderson, Paul J; Miller, Andrew D; O'Malley, Kathy A; Richert, Maile L; Johnson, Jacob B; Johnson, Bruce D

    2013-01-01

    Exposure to altitudes >2500 m can result in acute mountain sickness (AMS), a mild and usually self-limiting condition. Research has attempted to identify factors associated with developing AMS without controlling important factors related to the ascent or collecting a comprehensive set of variables. Objectives The Antarctic Study of Altitude Physiology (ASAP) investigated variables associated with the development of AMS in adults experiencing rapid passive transport to altitude by airplane. Design Our prospective observational trial collected data, including personal history, anthropometrics, vital signs, blood samples and pulmonary function, at sea level and at altitude. Statistical analysis utilised independent sample t tests to investigate between-group differences (p<0.05) and a forward, step-wise binary logisitic regression analysis was performed. Participants Of 248 eligible ASAP participants, those who did not use acetazolamide (N=98) were included in the present analysis. Primary outcome measures The diagnosis of AMS using the Lake Louise Symptom Score. Results Analysis of participants not using acetazolamide (n=90) found 30 participants developed AMS and 60 participants did not. Estimated plasma volume decreased significantly at altitude (p=0.025) in the AMS group as compared with the No AMS group while body weight did not change (p=0.125). Serum sodium (p=0.045) and low-density lipoprotein (LDL) (p=0.049) levels were higher in the No AMS group. A logistic regression analysis emphasised the contributions of LDL and eosinophil levels in the development of AMS. Conclusions These results suggest that the body water regulation and inflammation are key factors in AMS development when all other factors such as the level of physical exertion during ascent, the rate and magnitude of ascent and the use of acetazolamide are controlled. PMID:23869103

  7. Bulk and surface sensitivity of a resonant waveguide grating imager

    NASA Astrophysics Data System (ADS)

    Orgovan, Norbert; Kovacs, Boglarka; Farkas, Eniko; Szabó, Bálint; Zaytseva, Natalya; Fang, Ye; Horvath, Robert

    2014-02-01

    We report the assessment of the sensitivity of a microplate-compatible resonant waveguide grating imager. The sensitivity to bulk refractive index changes was determined using a serial dilution of glycerol solution with the help of a refractometer. The surface sensitivity was examined using layer-by-layer polyelectrolyte films in conjunction with optical waveguide lightmode spectroscopy and characterized by the binding of acetazolamide to immobilized carbonic anhydrase under microfluidics. The results suggest that the imager has a limit of detection down to 2.2 × 10-6 for refractive index change and 0.078 ng/cm2 for the adsorbed mass.

  8. Raised intracranial pressure and visual complications in AIDS patients with cryptococcal meningitis.

    PubMed

    Johnston, S R; Corbett, E L; Foster, O; Ash, S; Cohen, J

    1992-03-01

    The clinical course of cryptococcal meningitis in AIDS shows some important differences from the features of the illness in non-AIDS patients. Complications such as raised intracranial pressure and visual impairment that are recognised in non-AIDS patients may be less frequent in those with AIDS. Persistent intracranial hypertension should be managed actively to prevent visual impairment. In AIDS patients, in whom ventriculo-peritoneal shunts carry additional risks, acetazolamide can be used successfully to lower the CSF pressure and prevent visual loss.

  9. [Cytoprotection of gastric mucosa induced by tripotassium-dicitrato bismuthate against ethanol stress. Dependent mechanisms of sulfhydryl, dopaminergic and endogenous prostaglandin].

    PubMed

    Laudanno, O M; Bodini, O A; San Miguel, P; Cesolari, J A; Capdopon, E

    1986-01-01

    In groups of white Wistar rats, the cytoprotective effect induced by TDB on the gastric mucosa against the ethanol injury, was studied; where macroscopic protection and histologic cytoprotection in gastric corpus was found, and no in antrum mucosa. The cytoprotective mechanism give by TDB, were studied by the test of Indomethacin, Cl2Hg, Domperidone, Chlorpromazine and Acetazolamide, where each drug was given as pretreatment. Was conclude that TDB give gastric cytoprotection by the mechanism of the nonprotein sulfhydryl, by to be one peripheral agonist of the neuronal dopamine receptors, by increase of endogenous prostaglandin, by little increment of cAMP and no participate the gastric bicarbonate secretion.

  10. Neuro-Ophthalmological Manifestations after Intramuscular Medroxyprogesterone: A Forme Fruste of Idiopathic Intracranial Hypertension?

    PubMed

    Bahall, Mandreker; Reyes, Antonio Jose; Ramcharan, Kanterpersad; Hosein, Nadeem; Seegobin, Karan; Bahall, Krishni; Sharma, Hiranyadeva; Dhansingh, Stephanie; Mahabir, Amanda

    2016-09-30

    We report a case of a 22-year-old female student nurse who presented to hospital with an acute neuro-ophthalmological syndrome characterized by papilledema, ataxia, ophthalmoplegia and headache after a single first time use of 150 mg medroxyprogesterone intramuscular injection. Clinical, laboratory, radiological and ophthalmological investigations were in keeping with the diagnosis of idiopathic intracranial hypertension but lumbar puncture did not show a raised cerebrospinal fluid pressure suggesting a forme fruste of this entity. Her neuro-ophthalmological clinical features responded well to acetazolamide and diagnostic/therapeutic lumbar puncture. Full recovery was achieved three months after medroxyprogesterone usage. Health care providers must be aware of this adverse drug reaction.

  11. [Idiopathic intracranial hypertension].

    PubMed

    Bäuerle, J; Egger, K; Harloff, A

    2017-02-01

    This review describes the clinical findings as well as thes diagnostic and therapeutic options for idiopathic intracranial hypertension (pseudotumor cerebri). Furthermore, the pathophysiological concepts are discussed. Idiopathic intracranial hypertension is characterized by signs and symptoms of raised intracranial pressure with no established pathogenesis. Common symptoms include headaches, visual loss and pulsatile tinnitus. Treatment has two major goals: the alleviation of headaches and the preservation of vision. Weight loss and acetazolamide are the cornerstones in the treatment of the disorder. Drainage of cerebrospinal fluid, optic nerve sheath fenestration and stent angioplasty of a sinus stenosis can be employed in severe cases.

  12. Evaluation and management of the swollen optic disk in cryptococcal meningitis.

    PubMed

    Rigi, Mohammed; Khan, Khurrum; Smith, Stacy V; Suleiman, Ayman O; Lee, Andrew G

    Cryptococcal meningitis is the most common and severe form of cryptococcal infection. In addition to infiltrative and inflammatory mechanisms, intracranial hypertension commonly complicates cryptococcal meningitis and may cause significant visual and neurological morbidity and mortality. The mainstays of treatment for cryptococcal meningitis include standard antifungal therapy, management of intracranial hypertension, and treatment of underlying immunosuppressive conditions. Early and aggressive management of intracranial hypertension in accordance with established guidelines reduces the risk of long-term visual and neurological complications and death. Traditional recommendations for treating elevated intracranial pressure in idiopathic intracranial hypertension including acetazolamide, weight loss, and avoiding serial lumbar punctures-are not helpful in cryptococcal meningitis and may be harmful.

  13. Preparation of sulfonamides from N-silylamines

    PubMed Central

    Naredla, Rajasekhar Reddy; Klumpp, Douglas A.

    2013-01-01

    Sulfonamides have been prepared in high yields by the reactions of N-silylamines with sulfonyl chlorides and fluorides. In a competition experiment, the sulfonyl chlorides were found to be far more reactive than sulfonyl fluorides. The chemistry may be used to prepare aliphatic, aromatic, tertiary, secondary, and primary sulfonamides. It may also be done in the absence of solvent and the byproduct trimethylsilyl chloride recovered in good yield. Primary sulfonamides were synthesized from the sulfonyl chloride with aminotriphenyl silane (Ph3SiNH2), a conversion demonstrated with the synthesis of the carbonic anhydrase inhibitor, acetazolamide.

  14. Acute pulmonary oedema on the Ruwenzori mountain range.

    PubMed Central

    Naeije, R; Mélot, C

    1990-01-01

    A 40 year old man had an episode of severe pulmonary oedema at 4000-5000 m during the ascent of the Margherita peak (5109 m) of Mount Stanley on the Ruwenzori. He had taken acetazolamide and high dose dexamethasone to treat symptoms of acute mountain sickness. Six years before he had been studied by right heart catheterisation as a healthy volunteer during hypoxic breathing at sea level. His pulmonary vascular reactivity had been within the normal range for 32 healthy subjects. This man had high altitude pulmonary oedema despite currently recommended treatments for acute mountain sickness and normal pulmonary vascular reactivity to hypoxia at sea level. PMID:2271350

  15. Identification of Bicarbonate as a Trigger and Genes Involved with Extracellular DNA Export in Mycobacterial Biofilms.

    PubMed

    Rose, Sasha J; Bermudez, Luiz E

    2016-12-06

    Extracellular DNA (eDNA) is an integral biofilm matrix component of numerous pathogens, including nontuberculous mycobacteria (NTM). Cell lysis is the source of eDNA in certain bacteria, but the source of eDNA remains unidentified for NTM, as well as for other eDNA-containing bacterial species. In this study, conditions affecting eDNA export were examined, and genes involved with the eDNA export mechanism were identified. After a method for monitoring eDNA in real time in undisturbed biofilms was established, different conditions affecting eDNA were investigated. Bicarbonate positively influenced eDNA export in a pH-independent manner in Mycobacterium avium, M. abscessus, and M. chelonae The surface-exposed proteome of M. avium in eDNA-containing biofilms revealed abundant carbonic anhydrases. Chemical inhibition of carbonic anhydrases with ethoxzolamide significantly reduced eDNA export. An unbiased transposon mutant library screen for eDNA export in M. avium identified many severely eDNA-attenuated mutants, including one not expressing a unique FtsK/SpoIIIE-like DNA-transporting pore, two with inactivation of carbonic anhydrases, and nine with inactivation of genes belonging to a unique genomic region, as well as numerous mutants involved in metabolism and energy production. Complementation of nine mutants that included the FtsK/SpoIIIE and carbonic anhydrase significantly restored eDNA export. Interestingly, several attenuated eDNA mutants have mutations in genes encoding proteins that were found with the surface proteomics, and many more mutations are localized in operons potentially encoding surface proteins. Collectively, our data strengthen the evidence of eDNA export being an active mechanism that is activated by the bacterium responding to bicarbonate.

  16. Comparative evaluation of Na(+) uptake in Cyprinodon variegatus variegatus (Lacepede) and Cyprinodon variegatus hubbsi (Carr) (Cyprinodontiformes, Teleostei): Evaluation of NHE function in high and low Na(+) freshwater.

    PubMed

    Brix, Kevin V; Esbaugh, Andrew J; Mager, Edward M; Grosell, Martin

    2015-07-01

    The euryhaline pupfish, Cyprinodon variegatus variegatus (Cvv), can successfully osmoregulate in ≥2 mM Na(+) and a freshwater population (Cyprinodon variegatus hubbsi; Cvh) osmoregulates at ≥0.1mM Na(+). We previously demonstrated that Cvv relies on an apical NKCC and NHE in the gill for Na(+) uptake in high (7mM) and intermediate (2 mM) Na(+) concentrations, while Cvh relies only on NHE for Na(+) uptake. This study investigated whether differential NHE isoform use explains differences in Na(+) uptake kinetics between these two populations. We further studied whether Cvh uses a NHE-Rh metabolon or carbonic anhydrase (CA) to overcome thermodynamic challenges of NHE function in dilute freshwater. Transfer to more dilute freshwater resulted in upregulation of nhe-2 (Cvv only) and nhe-3 (Cvv and Cvh). Relative expression of nhe-3 compared to nhe-2 was 2-fold higher in Cvv, but 200-fold higher in Cvh suggesting that nhe-3 expression is an important freshwater adaptation for Cvh. Simultaneous measurement of Na(+) and Tamm flux under various conditions provided no support for a NHE-Rh metabolon in either population. Carbonic anhydrase activity in Cvv was comparable in 7 and 2 mM Na(+) acclimated fish. In Cvh, CA activity increased by 75% in 0.1 mM Na(+) acclimated fish compared to 7 mM Na(+) fish. Ethoxzolamide had variable effects, stimulating and reducing Na(+) uptake in Cvv acclimated to 7 and 2 mM Na(+), while reducing Na(+) uptake in 7 and 0.1mM Na(+) acclimated Cvh. This suggests that CA plays important, but different roles in regulating Na(+) uptake in Cvv and Cvh.

  17. Characterization of Na+ uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard)

    PubMed Central

    Brix, Kevin V.; Grosell, Martin

    2013-01-01

    This study provided an initial characterization of Na+ uptake in saline freshwater by the endangered pupfish, Cyprinodon macularius. This species occurs only in several saline water systems in the southwestern USA and northern Mexico, where salinity is largely controlled by water-management practices. Consequently, understanding the osmoregulatory capacity of this species is important for their conservation. The lower acclimation limit of C. macularius in freshwater was found to be 2 mM Na+. Fish acclimated to 2 or 7 mM Na+ displayed similar Na+ uptake kinetics, with Km values of 4321 and 3672 μM and Vmax values of 4771 and 3602 nmol g−1 h−1, respectively. A series of experiments using pharmacological inhibitors indicated that Na+ uptake in C. macularius was not sensitive to bumetanide, metolazone, or phenamil. These results indicate the Na+–K+–2Cl− cotransporter, Na+–Cl− cotransporter, and the Na+ channel–H+-ATPase system are likely not to be involved in Na+ uptake at the apical membrane of fish gill ionocytes in fish acclimated to 2 or 7 mM Na+. However, Na+ uptake was sensitive to 1 × 10−3 M amiloride (not 1 × 10−4 or 1 × 10−5 M), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and ethoxzolamide. These data suggest that C. macularius relies on a low-affinity Na+–H+ exchanger for apical Na+ uptake and that H+ ions generated via carbonic anhydrase-mediated CO2 hydration are important for the function of this protein. PMID:27293589

  18. Characterization of Na(+) uptake in the endangered desert pupfish, Cyprinodon macularius (Baird and Girard).

    PubMed

    Brix, Kevin V; Grosell, Martin

    2013-01-01

    This study provided an initial characterization of Na(+) uptake in saline freshwater by the endangered pupfish, Cyprinodon macularius. This species occurs only in several saline water systems in the southwestern USA and northern Mexico, where salinity is largely controlled by water-management practices. Consequently, understanding the osmoregulatory capacity of this species is important for their conservation. The lower acclimation limit of C. macularius in freshwater was found to be 2 mM Na(+). Fish acclimated to 2 or 7 mM Na(+) displayed similar Na(+) uptake kinetics, with K m values of 4321 and 3672 μM and V max values of 4771 and 3602 nmol g(-1) h(-1), respectively. A series of experiments using pharmacological inhibitors indicated that Na(+) uptake in C. macularius was not sensitive to bumetanide, metolazone, or phenamil. These results indicate the Na(+)-K(+)-2Cl(-) cotransporter, Na(+)-Cl(-) cotransporter, and the Na(+) channel-H(+)-ATPase system are likely not to be involved in Na(+) uptake at the apical membrane of fish gill ionocytes in fish acclimated to 2 or 7 mM Na(+). However, Na(+) uptake was sensitive to 1 × 10(-3) M amiloride (not 1 × 10(-4) or 1 × 10(-5) M), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and ethoxzolamide. These data suggest that C. macularius relies on a low-affinity Na(+)-H(+) exchanger for apical Na(+) uptake and that H(+) ions generated via carbonic anhydrase-mediated CO2 hydration are important for the function of this protein.

  19. Identification of Bicarbonate as a Trigger and Genes Involved with Extracellular DNA Export in Mycobacterial Biofilms

    PubMed Central

    Rose, Sasha J.

    2016-01-01

    ABSTRACT Extracellular DNA (eDNA) is an integral biofilm matrix component of numerous pathogens, including nontuberculous mycobacteria (NTM). Cell lysis is the source of eDNA in certain bacteria, but the source of eDNA remains unidentified for NTM, as well as for other eDNA-containing bacterial species. In this study, conditions affecting eDNA export were examined, and genes involved with the eDNA export mechanism were identified. After a method for monitoring eDNA in real time in undisturbed biofilms was established, different conditions affecting eDNA were investigated. Bicarbonate positively influenced eDNA export in a pH-independent manner in Mycobacterium avium, M. abscessus, and M. chelonae. The surface-exposed proteome of M. avium in eDNA-containing biofilms revealed abundant carbonic anhydrases. Chemical inhibition of carbonic anhydrases with ethoxzolamide significantly reduced eDNA export. An unbiased transposon mutant library screen for eDNA export in M. avium identified many severely eDNA-attenuated mutants, including one not expressing a unique FtsK/SpoIIIE-like DNA-transporting pore, two with inactivation of carbonic anhydrases, and nine with inactivation of genes belonging to a unique genomic region, as well as numerous mutants involved in metabolism and energy production. Complementation of nine mutants that included the FtsK/SpoIIIE and carbonic anhydrase significantly restored eDNA export. Interestingly, several attenuated eDNA mutants have mutations in genes encoding proteins that were found with the surface proteomics, and many more mutations are localized in operons potentially encoding surface proteins. Collectively, our data strengthen the evidence of eDNA export being an active mechanism that is activated by the bacterium responding to bicarbonate. PMID:27923918

  20. Characteristics of the proton pump in rat renal cortical endocytotic vesicles.

    PubMed

    Sabolić, I; Burckhardt, G

    1986-05-01

    The characteristics of the H+ pump in isolated rat renal endocytotic vesicles were studied by the delta pH-sensitive dye acridine orange, the voltage-sensitive dye 3,3'-dipropylthiadicarbocyanine iodide, and by a coupled optical ATPase assay. Intravesicular acidification depended on ATP and Mg2+ concentrations with half-maximal activations at 73 and 77 microM, respectively. CTP, GTP, UTP, and ITP partially supported acidification, but ADP and AMP did not. Ouabain, ethoxzolamide, levamisole, and vanadate did not inhibit H+ uptake into endocytotic vesicles. Oligomycin inhibited partially. Depending on concentration and preincubation time, Dio-9, filipin, N-ethylmaleimide (NEM), and dicyclohexylcarbodiimide (DCCD) inhibited H+ uptake completely. Filipin and, partially, DCCD acted nonspecifically by dissipating pH gradients. A specific cation was not required for the H+ pump; Zn2+ inhibited. Compared with mannitol, ATP-driven H+ uptake was stimulated by SCN- greater than Cl- greater than Br- greater than I- much greater than HPO4(2-) = gluconate = HCO3- = F-, but not by SO4(2-), NO3-, CH3COO-, S2O3(2-), and S4O6(2-). Chloride stimulated H+ uptake from the outside of the vesicles with an apparent Km of 27 mM. In the absence of Cl-, ATP-driven proton uptake was increased by intravesicular K+ and valinomycin, suggesting that the pump is electrogenic. The electrogenicity, however, could not be demonstrated with voltage-sensitive dyes. The vesicle membrane contains no significant K+ and Cl- conductances; only a conductance for H+ was found. The vesicles exhibited an ouabain-, oligomycin-, and vanadate-insensitive ATPase activity that was inhibited by DCCD and NEM. Our data indicate the presence of an electrogenic H+ pump in endocytotic vesicles from rat renal proximal tubules with similar characteristics as H+ pumps present in various intracellular (nonmitochondrial) membranes.

  1. Metabolic Effect of Estrogen Receptor Agonists on Breast Cancer Cells in the Presence or Absence of Carbonic Anhydrase Inhibitors

    PubMed Central

    Belkaid, Anissa; Čuperlović-Culf, Miroslava; Touaibia, Mohamed; Ouellette, Rodney J.; Surette, Marc E.

    2016-01-01

    Metabolic shift is one of the major hallmarks of cancer development. Estrogen receptor (ER) activity has a profound effect on breast cancer cell growth through a number of metabolic changes driven by its effect on transcription of several enzymes, including carbonic anhydrases, Stearoyl-CoA desaturase-1, and oncogenes including HER2. Thus, estrogen receptor activators can be expected to lead to the modulation of cell metabolism in estrogen receptor positive cells. In this work we have investigated the effect of 17β-estradiol, an ER activator, and ferulic acid, a carbonic anhydrase inhibitor, as well as ER activator, in the absence and in the presence of the carbonic anhydrase inhibitor acetazolamide on the metabolism of MCF7 cells and MCF7 cells, stably transfected to express HER2 (MCF7HER2). Metabolic profiles were studied using 1D and 2D metabolomic Nuclear Magnetic Resonance (NMR) experiments, combined with the identification and quantification of metabolites, and the annotation of the results in the context of biochemical pathways. Overall changes in hydrophilic metabolites were largest following treatment of MCF7 and MC7HER2 cells with 17β-estradiol. However, the carbonic anhydrase inhibitor acetazolamide had the largest effect on the profile of lipophilic metabolites. PMID:27240414

  2. Hypotony and ciliochoroidal detachment following pharmacologic aqueous suppressant therapy in previously filtered patients.

    PubMed

    Vela, M A; Campbell, D G

    1985-01-01

    This is the first report describing the syndrome of hypotony and ciliochoroidal detachment following pharmacologic aqueous suppressant therapy in previously filtered eyes. Four patients had a history of advanced primary open-angle glaucoma treated with multiple medical therapies, including timolol for 11 to 36 months. They then underwent filtration surgery, which failed in two cases. Timolol and/or acetazolamide therapy was instituted 1 to 18 months following surgery. The patients then developed hypotony and ciliochoroidal detachment, which resolved spontaneously after cessation of the pharmacologic aqueous suppressant therapy. In three of the cases, the episode of hypotony and ciliochoroidal detachment recurred after a second challenge with timolol and/or acetazolamide therapy. Inflammation, tumor, wound leakage, retinal detachment and cyclodialysis cleft were excluded. A mechanism of formation of ciliochoroidal detachment in this syndrome is proposed. Long-term timolol therapy followed by filtration surgery and its attendant postoperative hypotony and ciliochoroidal detachment sensitizes the ciliary epithelium. Subsequent pharmacologic aqueous suppressant therapy results in almost total reduction of aqueous production, causing hypotony and ciliochoroidal detachment.

  3. Breathing and sleep at high altitude.

    PubMed

    Ainslie, Philip N; Lucas, Samuel J E; Burgess, Keith R

    2013-09-15

    We provide an updated review on the current understanding of breathing and sleep at high altitude in humans. We conclude that: (1) progressive changes in pH initiated by the respiratory alkalosis do not underlie early (<48 h) ventilatory acclimatization to hypoxia (VAH) because this still proceeds in the absence of such alkalosis; (2) for VAH of longer duration (>48 h), complex cellular and neurochemical re-organization occurs both in the peripheral chemoreceptors as well as within the central nervous system. The latter is likely influenced by central acid-base changes secondary to the extent of the initial respiratory responses to initial exposure to high altitude; (3) sleep at high altitude is disturbed by various factors, but principally by periodic breathing; (4) the extent of periodic breathing during sleep at altitude intensifies with duration and severity of exposure; (5) complex interactions between hypoxic-induced enhancement in peripheral and central chemoreflexes and cerebral blood flow--leading to higher loop gain and breathing instability--underpin this development of periodic breathing during sleep; (6) because periodic breathing may elevate rather than reduce mean SaO2 during sleep, this may represent an adaptive rather than maladaptive response; (7) although oral acetazolamide is an effective means to reduce periodic breathing by 50-80%, recent studies using positive airway pressure devices to increase dead space, hyponotics and theophylline are emerging but appear less practical and effective compared to acetazolamide. Finally, we suggest avenues for future research, and discuss implications for understanding sleep pathology.

  4. Mercury poisoning as a cause of intracranial hypertension.

    PubMed

    Gençpınar, Pınar; Büyüktahtakın, Başak; İbişoğlu, Zeynep; Genç, Şakir; Yılmaz, Aygen; Mıhçı, Ercan

    2015-05-01

    Mercury poisoning is a rare but fatal toxicologic emergency. Neurologic manifestations involving the central nervous system are seen usually with chronic mercury intoxication. The most commonly seen complaints are headache, tremor, impaired cognitive skills, weakness, muscle atrophy, and paresthesia. Here, we present a male patient who was chronically exposed to elemental mercury and had papilledema and intracranial hypertension without parenchymal lesion in the central nervous system. A 12-year-old male patient was referred to our emergency room because of severe fatigue, generalized muscle pain and weakness, which was present for a month. Physical examination revealed painful extremities, decreased motor strength and the lack of deep tendon reflexes in lower extremities. He had mixed type polyneuropathy in his electromyography. Whole blood and 24-hour urinary mercury concentrations were high. A chelation therapy with succimer (dimercaptosuccinic acid) was started on the fourth day of his admission. On the seventh day of his admission, he developed headache and nausea, and bilateral papilledema and intracranial hypertension were detected on physical examination. Acetazolamide was started and after 1 month of treatment, the fundi examination was normal. The patient stayed in the hospital for 35 days and was then discharged with acetazolamide, vitamin B6, gabapentin, and followed as an outpatient. His clinical findings were relieving day by day. Although headache is the most common symptom in mercury poisoning, the clinician should evaluate the fundus in terms of intracranial hypertension.

  5. Pseudotumor Cerebri in a Child with Idiopathic Growth Hormone Insufficiency Two Months after Initiation of Recombinant Human Growth Hormone Treatment

    PubMed Central

    Loukianou, Eleni; Tasiopoulou, Anastasia; Demosthenous, Constantinos; Brouzas, Dimitrios

    2016-01-01

    Purpose. To report a rare case of pseudotumor cerebri (PTC) in a child two months after receiving treatment with recombinant human growth hormone (rhGH) and to emphasize the need of close collaboration between ophthalmologists and pediatric endocrinologists in monitoring children receiving rhGH. Methods. A 12-year-old boy with congenital hypothyroidism started treatment with rhGH on a dose of 1,5 mg/daily IM (4.5 IU daily). Eight weeks later, he was complaining of severe headache without any other accompanying symptoms. The child was further investigated with computed tomography scan and lumbar puncture. Results. Computed tomography scan showed normal ventricular size and lumbar puncture revealed an elevated opening pressure of 360 mm H2O. RhGH was discontinued and acetazolamide 250 mg per os twice daily was initiated. Eight weeks later, the papilledema was resolved. Conclusions. There appears to be a causal relationship between the initiation of treatment with rhGH and the development of PTC. All children receiving rhGH should have a complete ophthalmological examination if they report headache or visual disturbances shortly after the treatment. Discontinuation of rhGH and initiation of treatment with acetazolamide may be needed and regular follow-up examinations by an ophthalmologist should be recommended. PMID:26966604

  6. Role of carbonic anhydrase in bone resorption induced by prostaglandin E2 in vitro

    NASA Technical Reports Server (NTRS)

    Hall, G. E.; Kenny, A. D.

    1985-01-01

    The possible role of carbonic anhydrase in bone resorption induced by prostaglandin E2 (PGE2) was studied using an in vitro neonatal mouse calvarial culture system. PGE2 (10 to the -6th M) was effective in stimulating resorption, as assessed by calcium release into culture media. This enhanced resorption was accompanied by significant increases in calvarial carbonic anhydrase activity over control values at 48 and 96 h. At 48 h, bones treated with PGE2 had 20 percent more carbonic anhydrase activity than controls. By 96 h, treated bones contained 79 percent more carbonic anhydrase activity than controls. PGE2-induced bone resorption was inhibited by the carbonic anhydrase inhibitor acetazolamide in a dose-dependent fashion from 10 to the -5th to 10 to the -4th M with 77 percent inhibition observed at 10 to the -4th M. The acetazolamide analogue CL 13,850 (N-t-butylacetazolamide), which does not inhibit carbonic anhydrase, failed to inhibit PGE2-induced resorption. These results are consistent with the hypothesis that carbonic anhydrase is a necessary component of the osteoclastic bone resorptive mechanism.

  7. High-altitude illnesses: physiology, risk factors, prevention, and treatment.

    PubMed

    Taylor, Andrew T

    2011-01-01

    High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-acclimatized individuals after rapid ascent to high altitude. The most common syndrome is acute mountain sickness (AMS) which usually begins within a few hours of ascent and typically consists of headache variably accompanied by loss of appetite, nausea, vomiting, disturbed sleep, fatigue, and dizziness. With millions of travelers journeying to high altitudes every year and sleeping above 2,500 m, acute mountain sickness is a wide-spread clinical condition. Risk factors include home elevation, maximum altitude, sleeping altitude, rate of ascent, latitude, age, gender, physical condition, intensity of exercise, pre-acclimatization, genetic make-up, and pre-existing diseases. At higher altitudes, sleep disturbances may become more profound, mental performance is impaired, and weight loss may occur. If ascent is rapid, acetazolamide can reduce the risk of developing AMS, although a number of high-altitude travelers taking acetazolamide will still develop symptoms. Ibuprofen can be effective for headache. Symptoms can be rapidly relieved by descent, and descent is mandatory, if at all possible, for the management of the potentially fatal syndromes of high-altitude pulmonary and cerebral edema. The purpose of this review is to combine a discussion of specific risk factors, prevention, and treatment options with a summary of the basic physiologic responses to the hypoxia of altitude to provide a context for managing high-altitude illnesses and advising the non-acclimatized high-altitude traveler.

  8. Renal carbonic anhydrases are involved in the reabsorption of endogenous nitrite.

    PubMed

    Chobanyan-Jürgens, Kristine; Schwarz, Alexandra; Böhmer, Anke; Beckmann, Bibiana; Gutzki, Frank-Mathias; Michaelsen, Jan T; Stichtenoth, Dirk O; Tsikas, Dimitrios

    2012-02-15

    Nitrite (ONO(-)) exerts nitric oxide (NO)-related biological actions and its concentration in the circulation may be of particular importance. Nitrite is excreted in the urine. Hence, the kidney may play an important role in nitrite/NO homeostasis in the vasculature. We investigated a possible involvement of renal carbonic anhydrases (CAs) in endogenous nitrite reabsorption in the proximal tubule. The potent CA inhibitor acetazolamide was administered orally to six healthy volunteers (5 mg/kg) and nitrite was measured in spot urine samples before and after administration. Acetazolamide increased abruptly nitrite excretion in the urine, strongly suggesting that renal CAs are involved in nitrite reabsorption in healthy humans. Additional in vitro experiments support our hypothesis that nitrite reacts with CO(2), analogous to the reaction of peroxynitrite (ONOO(-)) with CO(2), to form acid-labile nitrito carbonate [ONOC(O)O(-)]. We assume that this reaction is catalyzed by CAs and that nitrito carbonate represents the nitrite form that is actively transported into the kidney. The significance of nitrite reabsorption in the kidney and the underlying mechanisms, notably a direct involvement of CAs in the reaction between nitrite and CO(2), remain to be elucidated.

  9. Stimulatory effect of Coca-Cola on gastroduodenal HCO3- secretion in rats.

    PubMed

    Sasaki, Y; Aihara, E; Ise, F; Kita, K; Takeuchi, K

    2007-10-01

    We examined the effect of various carbonated beverages, especially Coca-Cola, on the HCO3- secretion in the rat stomach and duodenum. Under urethane anaesthesia, a chambered stomach or a proximal duodenal loop was perfused with saline, and HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 2 mM HCl. The amount of CO2 contained in these beverages was about 4-7 g/mL. Coca-Cola topically applied to the mucosa for 10 min significantly increased the HCO3- secretion in both the stomach and the duodenum. The HCO3- response in the duodenum was totally abolished by indomethacin and also partially inhibited by acetazolamide, an inhibitor of carbonic anhydrase. Likewise, the response in the stomach was also markedly inhibited by either acetazolamide or indomethacin. The mucosal application of Coca-Cola increased the PGE2 contents in both the stomach and the duodenum. Other carbonated beverages, such as sparkling water, Fanta Grape or cider, also increased the HCO3- secretion in these tissues. These results suggest that Coca-Cola induces HCO3- secretion in both the stomach and the duodenum, and these responses may be attributable to both the intracellular supply of HCO3- generated via carbonic anhydrase, and endogenous PGs, probably related to the acidic pH of the solution.

  10. Use of the accelerating rotarod for assessment of motor performance decrement induced by potential anticonvulsant compounds in nerve agent poisoning. (Reannouncement with new availability information)

    SciTech Connect

    Capacio, B.R.; Harris, L.W.; Anderson, D.R.; Lennox, W.J.; Gales, V.

    1992-12-31

    The accelerating rotarod was used to assess motor performance decrement in rats after administration of candidate anticonvulsant compounds (acetazolamide, amitriptyline, chlordiazepoxide, diazepan, diazepam-lysine, lorazepam, loprazolam, midazolam, phenobarbital and scopolamine) against nerve agent poisoning. AH compounds were tested as the commercially available injectable preparation except for diazepam-lysine and loprazolam, which are not FDA approved. A peak effect time, as well as a dose to decrease performance time by 50% from control (PDD50), was determined. The calculated PDD50 (micrometer ol/kg) values and peak effect tunes were midazolam, 1.16 at 15 min; loprazolam, 1.17 at 15 min; diazepam-lysine, 4.17 at 30 min; lorazepwn, 4.98 at 15 min; diazepam, 5.27 at 15 min; phenobarbital, 101.49 at 45 min; chlordiazepoxide, 159.21 at 30 min; scopolamine, amitriptyline and acetazolamide did not demonstrate a performance decrement at any of the doses tested. The PDD50 values were compared with doses which have been utilized against nerve agent-induced convulsions or published ED50 values from standard anticonvulsant screening tests (maximal electroshock MES and subcutaneous pentylenetetrazol (scMET)). I serve agents, anticonvulsants, diazepam, accelerating rotarod, motor performance.

  11. Intracranial haemodynamics during vasomotor stress test in unilateral internal carotid artery occlusion estimated by 3-D transcranial Doppler scanner.

    PubMed

    Zbornikova, V; Lassvik, C; Hillman, J

    1995-04-01

    Seventeen patients, 14 males and 3 females, mean age 64 years (range 45-77 years) with longstanding unilateral occlusion of the internal carotid artery and minimal neurological deficit, were evaluated in order to find criteria for potential benefit of extracranial-intracranial by-pass surgery. 3-D transcranial Doppler was used for estimation of mean velocities and pulsatility index in the middle cerebral artery, anterior cerebral artery and posterior cerebral artery before and after iv injection of 1 g acetazolamide. The anterior cerebral artery was the supplying vessel to the occluded side in 16 patients and mean velocities were significantly (p < 0.001) faster on the occluded (59.3 +/- 14.5 cm sec-1) and nonoccluded (91.6 +/- 29.6 cm sec-1, p < 0.05)) side than those found in the middle cerebral artery (39.2 +/- 13.7 and 50.9 +/- 8.5 cm sec-1). In two patients a decrease of mean velocity after acetazolamide was noted in middle cerebral artery indicating 'steal' effect. In another 4 patients, poor vasomotor response was seen with less than 11% of mean velocity increase in the middle cerebral artery. Differences between posterior cerebral artery on the occluded and nonoccluded side were insignificant as well as those between middle and posterior on the occluded side. Resting values of pulsatility index differed significantly (p < 0.01) only between anterior and posterior cerebral artery on the nonoccluded side.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. pH-dependent association of carbonic anhydrase (CA) with gastric light microsomal membranes isolated from bovine abomasum. Partial characterization of membrane-associated activity.

    PubMed

    López Mañanes, A A; Daleo, G R; Vega, F V

    1993-05-01

    1. The effect of pH on the association of carbonic anhydrase (CA) with bovine gastric light microsomal membranes (LMMs) was investigated (a) by washing LMMs containing CA activity with solutions of different pHs; (b) by studying the adsorption at various pHs of soluble bovine erythrocyte CA to washed gastric LMMs. In both cases, the association of CA with gastric LMMs was dependent on pH, being lower at neutral or alkaline pH. 2. The amount of soluble CA associated with gastric LMMs at pHs 8.0 and 9.0 was reduced when 140 mM K+/10 mM Na+ was added to the incubation medium. 3. Two sources of CA activity in bovine gastric LMMs were assumed: a loosely- and a firmly-membrane-associated activity. Both CA activities were dose-dependently inhibited by acetazolamide (I50: 3.6 x 10(-9) and 8.4 x 10(-9) M, respectively) and by chloride, acetate, iodide, bromide and nitrate at 100 mM. Firmly-membrane-associated activity appeared to be less sensitive to inhibition by acetazolamide, chloride and iodide. 4. Both activities exhibited different behavior and stability following treatment with alkaline Triton X-100. 5. The possible importance of a membrane-associated CA activity in gastric LMMs related to gastric acid secretion is discussed.

  13. Alkalinization in the Isolated and Perfused Anterior Midgut of the Larval Mosquito, Aedes aegypti

    PubMed Central

    Onken, Horst; Moffett, Stacia B.; Moffett, David F.

    2008-01-01

    In the present study, isolated midguts of larval Aedes aegypti L. (Diptera: Culicidae) were mounted on perfusion pipettes and bathed in high buffer mosquito saline. With low buffer perfusion saline, containing m-cresol purple, transepithelial voltage was monitored and luminal alkalinization became visible through color changes of m-cresol purple after perfusion stop. Lumen negative voltage and alkalinization depended on metabolic energy and were stimulated in the presence of serotonin (0.2 µmol l-1). In some experiments a pH microelectrode in the lumen recorded pH values up to 10 within minutes after perfusion stop. The V-ATPase inhibitor concanamycin (50 µmol l-1) on the hemolymph side almost abolished Vte and inhibited luminal alkalinization. The carbonic anhydrase inhibitor, methazolamide (50 µmol l-1), on either the luminal or hemolymph-side, or the inhibitor of anion transport, DIDS (1 mmol l-1) on the luminal side, had no effect on Vte or alkalinization. Cl- substitution in the lumen or on both sides of the tissue affected Vte, but the color change of m-cresol purple was unchanged from control conditions. Hemolymph-side Na+ substitution or addition of the Na+/H+ exchange inhibitor, amiloride (200 µmol l-1), reduced Vte and luminal alkalinization. Luminal amiloride (200 µmol l-1) was without effects on Vte or alkalinization. High K+ (60 mmol l-1) in the lumen reduced Vte without affecting alkalinization. These results indicate that strong luminal alkalinization in isolated and perfused anterior midgut of larval A. aegypti depends on basolateral V-ATPase, but is apparently independent of carbonic anhydrase, apical Cl-/HCO3- exchange or apical K+/2H+ antiport. PMID:20307229

  14. Influence of Cerebral Blood Flow on Central Sleep Apnea at High Altitude

    PubMed Central

    Burgess, Keith R.; Lucas, Samuel J.E.; Shepherd, Kelly; Dawson, Andrew; Swart, Marianne; Thomas, Kate N.; Lucas, Rebekah A.I.; Donnelly, Joseph; Peebles, Karen C.; Basnyat, Rishi; Ainslie, Philip N.

    2014-01-01

    Study Objectives: To further our understanding of central sleep apnea (CSA) at high altitude during acclimatization, we tested the hypothesis that pharmacologically altering cerebral blood flow (CBF) would alter the severity of CSA at high altitude. Design: The study was a randomized, placebo-controlled single-blind study. Setting: A field study at 5,050 m in Nepal. Patients or Participants: We studied 12 normal volunteers. Interventions: Between days 5 to10 at high altitude, CBF velocity (CBFv) was increased by intravenous (IV) acetazolamide (10 mg/kg) and reduced by oral indomethacin (100 mg). Measurements and Results: Arterial blood gases, hypoxic and hypercapnic ventilatory responses, and CBFv and its reactivity to carbon dioxide were measured awake. Overnight polysomnography was performed. The central apnea-hypopnea index was elevated following administration of indomethacin (89.2 ± 43.7 to 112.5 ± 32.9 events/h; mean ± standard deviation; P < 0.05) and was reduced following IV acetazolamide (89.2 ± 43.7 to 47.1 ± 48.1 events/h; P < 0.001). Intravenous acetazolamide elevated CBFv at high altitude by 28% (95% confidence interval [CI]: 22-34%) but did not affect ventilatory responses. The elevation in CBFv was partly mediated via a selective rise in partial pressure of arterial carbon dioxide (PaCO2) (28 ± 4 to 31 ± 3 mm Hg) and an associated fall in pH (P < 0.01). Oral indomethacin reduced CBFv by 23% (95% CI: 16-30%), blunted CBFv reactivity, and increased the hypercapnic ventilatory response by 66% (95% CI: 30-102%) but had no effect on PaCO2 or pH. Conclusion: Our findings indicate an important role for cerebral blood flow regulation in the pathophysiology of central sleep apnea at high altitude. Citation: Burgess KR, Lucas SJE, Shepherd K, Dawson A, Swart M, Thomas KN, Lucas RAI, Donnelly J, Peebles KC, Basnyat R, Ainslie PN. Influence of cerebral blood flow on central sleep apnea at high altitude. SLEEP 2014;37(10):1679-1687. PMID:25197804

  15. Carbonic anhydrase inhibitors: inhibition of human and murine mitochondrial isozymes V with anions.

    PubMed

    Franchi, Marco; Vullo, Daniela; Gallori, Enzo; Antel, Jochen; Wurl, Michael; Scozzafava, Andrea; Supuran, Claudiu T

    2003-09-01

    In addition to sulfonamides, metal complexing anions represent the second class of inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The first inhibition study of the mitochondrial isozyme CA V (of murine and human origin) with anions is reported here. Inhibition data of the cytosolic isozymes CA I and CA II as well as the membrane-bound isozyme CA IV with a large number of anionic species such as halides, pseudohalides, bicarbonate, nitrate, hydrosulfide, arsenate, sulfamate, and sulfamidate and so on, are also provided for comparison. Isozyme V has an inhibition profile by anions completely different to those of CA I and IV, but similar to that of hCA II, which may have interesting physiological consequences. Similarly to hCA II, the mitochondrial isozymes show micro-nanomolar affinity for sulfonamides such as sulfanilamide and acetazolamide.

  16. Hit-Validation Methodologies for Ligands Isolated from DNA-Encoded Chemical Libraries.

    PubMed

    Zimmermann, Gunther; Li, Yizhou; Rieder, Ulrike; Mattarella, Martin; Neri, Dario; Scheuermann, Jörg

    2017-01-09

    DNA-encoded chemical libraries (DECLs) are large collections of compounds linked to DNA fragments, serving as amplifiable barcodes, which can be screened on target proteins of interest. In typical DECL selections, preferential binders are identified by high-throughput DNA sequencing, by comparing their frequency before and after the affinity capture step. Hits identified in this procedure need to be confirmed, by resynthesis and by performing affinity measurements. In this article we present new methods based on hybridization of oligonucleotide conjugates with fluorescently labeled complementary oligonucleotides; these facilitate the determination of affinity constants and kinetic dissociation constants. The experimental procedures were demonstrated with acetazolamide, a binder to carbonic anhydrase IX with a dissociation constant in the nanomolar range. The detection of binding events was compatible not only with fluorescence polarization methodologies, but also with Alphascreen technology and with microscale thermophoresis.

  17. Bilateral Choroidal Detachment Induced by Unilateral Application of a Fixed Combination of Topical Timolol Maleate and Brinzolamide

    PubMed Central

    DONMEZ, Oya; KILINC, Hilal; OZBEK, Zeynep; SAATCI, Ali Osman

    2016-01-01

    We describe a 66-year-old man who developed bilateral choroidal detachment that was induced by unilateral topical administration of a fixed combination of 1% brinzolamide and 0.5% timolol maleate the day after an uneventful phacoemulsification surgery and intraocular lens implantation involving his right eye. We believe that the reaction was an idiosyncratic reaction, most likely against brinzolamide. The condition improved rapidly after the cessation of the fixed combination of brinzolamide and timolol maleate and treatment with 1% topical prednisolone acetate every hour and 1% cyclopentolate twice a day bilaterally. Although there are several similar cases involving choroidal detachment after oral acetazolamide and topical dorzolamide treatment mentioned in the literature, the present case is the first case report involving bilateral choroidal detachment after topical treatment with brinzolamide.

  18. Symptomatic Middle Cerebral Artery Stenosis Treated by Percutaneous Transluminal Angioplasty: Improvement of Cerebrovascular Reserves

    PubMed Central

    Abe, A.; Ueda, T.; Ueda, M.; Nogoshi, S.; Nishiyama, Y.; Katayama, Y.

    2012-01-01

    Summary This study evaluated the recoveries of cerebrovascular reserves (CVR) after applying percutaneous transluminal angioplasty (PTA) to patients with symptomatic middle cerebral artery (MCA) stenosis of varying severity. The patients were submitted to single photon emission computed tomography (SPECT) to obtain their regional cerebral blood flows at resting stage (rCBFrest) and acetazolamide-challenged CBF in five regions of interest (ROIs), including the MCA, on the ipsilateral and contralateral sides of the hemisphere. rCVR values were then calculated from these CBF data to evaluate the CVR recoveries after PTA treatment. When the PTA effects were statistically analyzed of the patients dichotomized into more severe (n=9) and less severe (n=5) groups, distinctly significant ROI-specific PTA effectiveness was observed for CVR rather than CBF values in the patients of the severer group. PMID:22681739

  19. [Carbonic anhydrase of blue-green alga Spirulina platensis].

    PubMed

    Komarova, Iu M; Terekhova, I V; Doman, N G; Al'bitskaia, O N

    1976-01-01

    Carboanhydrase (carbonate-hydroliase EC 4.2.1.1.) is found in the extract of Spirulina platensis cells. A linear dependency of the enzyme activity on the protein concentration; pH optimum is found to be 8.0. Specific activity of carboanhydrase is 3 muM/min-mg of protein under the concentration of CO2 of 4-10(-3) M, appearing Michelis constant being 4.9-10(-3) M. The enzyme was stabilized with 10 mM of cisteine, its activity was inhibited by 50% with sulphanylamide (1-10(-5) M), acetazolamide (8--10(-7) M) and Cl- ions (5-10(-2) M). The activity of carboanhydrase, as well as the rate of NaH14CO3 fixation, depended on the pH value of cultural medium.

  20. Carbonic anhydrase inhibition for the management of cerebral ischemia: in vivo evaluation of sulfonamide and coumarin inhibitors.

    PubMed

    Di Cesare Mannelli, Lorenzo; Micheli, Laura; Carta, Fabrizio; Cozzi, Andrea; Ghelardini, Carla; Supuran, Claudiu T

    2016-12-01

    Ischemia of brain areas is a global health problem, causing death or long-term disability. Current pharmacological options have limited impact on ischemic damages. Recently, a relationship between hypoxia and carbonic anhydrase (CA) over-expression has been highlighted suggesting CA inhibition as a possible target. This study aimed to evaluate the pharmacological profile of sulfonamide and coumarin CA inhibitors in rats underwent permanent middle cerebral artery occlusion (pMCAO). The neurological score of pMCAO rats was dramatically reduced 24 h after occlusion. Repeated subcutaneous injections of the CA inhibitors 4 and 7 (1 mg kg(-1)) were able to increase the neurological score by 40%. Compound 7 showed the tendency to reduce the volume of hemisphere infarction. The standard CA inhibitor acetazolamide was ineffective. The properties of novel CA inhibitors to improve neurological functionalities after cerebral ischemic insult are shown. The CA involvement in cerebral hypoxic phenomena deserves deeper investigations.

  1. Chronic meningitis with intracranial hypertension and bilateral neuroretinitis following Mycoplasma pneumoniae infection.

    PubMed

    Karampatsas, Konstantinos; Patel, Himanshu; Basheer, Sheikh N; Prendergast, Andrew J

    2014-12-23

    A previously well 12-year-old boy presented with a 2-week history of headache, nausea, vomiting and left-sided weakness. He subsequently developed meningism, right abducens nerve palsy, persistent papilloedema and reduced visual acuity in association with a bilateral macular star, consistent with neuroretinitis. Cerebrospinal fluid (CSF) examination indicated chronic meningitis and serological testing confirmed recent Mycoplasma pneumoniae infection, although PCR in CSF was negative. He was treated for aseptic meningitis with ceftriaxone, aciclovir, azithromycin and acetazolamide for intracranial hypertension, with gradual improvement in clinical condition and visual acuity over several weeks. This is the first report of M. pneumoniae chronic meningitis further complicated with bilateral neuroretinitis and intracranial hypertension. Evidence of central nervous system inflammation in the absence of direct infection suggests an immune-mediated pathophysiology. Although the use of macrolides with antibiotic and immunomodulatory activity might be beneficial, it was not possible to ascertain whether it influenced clinical recovery in this case.

  2. [Pseudotumor cerebri secondary to consumption of minocycline in a pediatric patient].

    PubMed

    González Gili, Lucas O; Buffone, Ignacio R; Carrara, Laura E; Coto, María B; Fortunatti, Eliana A; Dejtera, Mabel; García Elliot, María F; Giacone, Alejandra; Luncio, Anabella C; Masnicoff, Sebastián D; Oviedo Crosta, María B; Parroua, Marianela; Romano, Mariana

    2016-04-01

    Pseudotumor cerebri is a syndrome characterized by an elevated intracranial pressure greater than 20 cmH2O with ventricles and cerebrospinal fluid of normal characteristics. Consumption of minocycline have been described among the causes associated with this syndrome. We present a 13-year old female patient with a history of acne treated with minocycline who began with severe headache, diplopia and blurred vision. The diagnosis of pseudotumor cerebri was made, indicating the immediate antibiotic suspension and the beginning of the treatment with acetazolamide. Although the pathogenesis of pseudotumor cerebri is not fully known, an association with minocycline has been observed. This antibiotic is often used by health professionals for the management of acne, so it is important to consider its complications before being prescribed.

  3. Type I Chiari malformation presenting central sleep apnea.

    PubMed

    Kitamura, Takuro; Miyazaki, Soichiro; Kadotani, Hiroshi; Kanemura, Takashi; Okawa, Masako; Tanaka, Toshihiko; Komada, Ichiro; Hatano, Taketo; Suzuki, Hideaki

    2014-04-01

    Sleep apnea is a rare but a well-known clinical feature of type I Chiari malformation. It may be obstructive or central in nature. Sleep apnea in patients with type I Chiari malformation rarely presents without accompanying neurological signs or symptoms. We here report a case of a 10-year-old girl who presented with central sleep apnea without any other neurological signs but was ultimately diagnosed with type I Chiari malformation. The patient initially showed mild improvement in symptoms after administration of an acetazolamide. Finally, posterior fossa decompression dramatically improved her respiratory status during sleep, both clinically and on polysomnography. This case suggests that type I Chiari malformation should be considered in the differential diagnoses of central apneas in children, even if there are no other neurological signs and symptoms. Furthermore, sagittal craniocervical magnetic resonance imaging may be necessary for a definitive diagnosis.

  4. Sudden blindness as a complication of percutaneous trigeminal procedures: mechanism analysis and prevention.

    PubMed

    Agazzi, Siviero; Chang, Stanley; Drucker, Mitchell D; Youssef, A Samy; Van Loveren, Harry R

    2009-04-01

    The authors describe the case of a 76-year-old man in whom reversible sudden blindness developed after a percutaneous balloon compression rhizotomy for trigeminal neuralgia. His eye became tense and swollen with intraocular pressures of 66 mm Hg. Acetazolamide was administered, and visual acuity (20/50) returned within several months. Despite correct needle placement, the intraocular pressure rose acutely because of transient occlusion of the orbital venous drainage through the cavernous sinus; this was reversed with aggressive medical treatment. In cadaveric studies (dried skull and formalin-fixed head), the authors studied the mechanism of optic nerve penetration. Their findings showed that excessive cranial angulation of the needle with penetration of the inferior orbital fissure can directly traumatize the optic nerve in the orbital apex. Direct trauma to the optic nerve can therefore be prevented by early and repeated confirmation of the needle trajectory with lateral fluoroscopy before penetration of the foramen ovale.

  5. Neuro-ophthalmology and neuro-otology update.

    PubMed

    Gold, Daniel R; Zee, David S

    2015-12-01

    This review summarizes topical papers from the fields of neuro-ophthalmology and neuro-otology published from August 2013 to February 2015. The main findings are: (1) diagnostic criteria for pseudotumor cerebri have been updated, and the Idiopathic Intracranial Hypertension Treatment Trial evaluated the efficacy of acetazolamide in patients with mild vision loss, (2) categorization of vestibular disorders through history and ocular motor examination is particularly important in the acute vestibular syndrome, where timely distinction between a central or peripheral localization is essential, (3) the newly described "sagging eye syndrome" provides a mechanical explanation for an isolated esodeviation that increases at distance in the aging population and (4) eye movement recordings better define how cerebellar dysfunction and/or sixth nerve palsy may play a role in other patients with esodeviations that increase at distance.

  6. Management of Root Resorption Using Chemical Agents: A Review

    PubMed Central

    Mohammadi, Zahed; C. Cehreli, Zafer; Shalavi, Sousan; Giardino, Luciano; Palazzi, Flavio; Asgary, Saeed

    2016-01-01

    Root resorption (RR) is defined as the loss of dental hard tissues because of clastic activity inside or outside of tooth the root. In the permanent dentition, RR is a pathologic event; if untreated, it might result in the premature loss of the affected tooth. Several hypotheses have been suggested as the mechanisms of root resorption such as absence of the remnants of Hertwig's epithelial root sheath (HERS) and the absence of some intrinsic factors in cementum and predentin such as amelogenin or osteoprotegerin (OPG). It seems that a barrier is formed by the less-calcified intermediate cementum or the cementodentin junction that prevents external RR. There are several chemical strategies to manage root resorption. The purpose of this paper was to review several chemical agents to manage RR such as tetracycline, sodium hypochlorite, acids (citric acid, phosphoric acid, ascorbic acid and hydrochloric acid), acetazolamide, calcitonin, alendronate, fluoride, Ledermix and Emdogain. PMID:26843869

  7. Medicine at high altitude.

    PubMed

    Wright, Alex D

    2006-01-01

    Medicine at high altitude provides important insights into the acute and chronic effects of hypoxia. Acute mountain sickness (AMS) is a common syndrome occurring after acute ascent to over 2,500 m and is caused by increased capillary permeability. A number of factors have been identified that increase the risk of AMS, in particular exercise. Avoiding rapid ascent, undue exercise and the use of acetazolamide are useful preventative measures but severe symptoms may require oxygen, dexamethasone and descent. Acute mountain sickness is usually self-limiting but may progress into the serious syndromes of pulmonary and cerebral oedema. Acclimatisation and adaptation are important for workers and residents at high altitude and the improvement seen in maximum exercise has been incorporated into some training schedules for endurance athletes. Chronic and subacute high-altitude diseases largely result from polycythemia and pulmonary hypertension.

  8. PET evaluation of cerebral blood flow reactivity in symptomatic and asymptomatic carotid artery stenosis

    SciTech Connect

    Dey, H.M.; Brass, L.; Rich, D.

    1994-05-01

    The purpose of this study was to use acetazolamide (AZ) enhanced O-15 water PET to evaluate cerebral perfusion reserve in symptomatic and asymptomatic carotid artery stenosis. We hypothesized that impaired vasoreactivity would be associated with symptomatic disease and a higher likelihood of future ischemic events. Twenty-two patients with significant (>75%) carotid artery occlusion underwent cerebral blood flow imaging at baseline and following AZ infusion. Paired O-15 data sets were coregistered and globally normalized. Regions of interest were drawn on baseline blood flow images and superimposed upon (AZ - baseline) difference images to derive a % change in regional blood flow after AZ administration. The results showed a significant difference in cerebral perfusion reserve between symptomatic (n=19) and asymptomatic (n=3) carotid artery disease.

  9. Effects of angiotensin, vasopressin and atrial natriuretic peptide on intraocular pressure in anesthetized rats

    NASA Technical Reports Server (NTRS)

    Palm, D. E.; Shue, S. G.; Keil, L. C.; Balaban, C. D.; Severs, W. B.

    1995-01-01

    The effects of atrial natriuretic peptide (ANP), vasopressin (AVP) and angiotensin (ANG) on blood and intraocular pressures of pentobarbital anesthetized rats were evaluated following intravenous, intracerebroventricular or anterior chamber routes of administration. Central injections did not affect intraocular pressure. Equipressor intravenous infusions of ANG raised, whereas AVP decreased, intraocular pressure. Direct infusions of a balanced salt solution (0.175 microliter/min) raised intraocular pressure between 30 and 60 min. Adding ANG or ANP slightly reduced this solvent effect but AVP was markedly inhibitory. An AVP-V1 receptor antagonist reversed the blunting of the solvent-induced rise by the peptide, indicating receptor specificity. Acetazolamide pretreatment lowered intraocular pressure, but the solvent-induced rise in intraocular pressure and inhibition by AVP still occurred without altering the temporal pattern. Thus, these effects appear unrelated to aqueous humor synthesis rate. The data support the possibility of intraocular pressure regulation by peptides acting from the blood and aqueous humor.

  10. A Gain-of-Function Mutation in NALCN in a Child with Intellectual Disability, Ataxia, and Arthrogryposis.

    PubMed

    Aoyagi, Kyota; Rossignol, Elsa; Hamdan, Fadi F; Mulcahy, Ben; Xie, Lin; Nagamatsu, Shinya; Rouleau, Guy A; Zhen, Mei; Michaud, Jacques L

    2015-08-01

    NALCN and its homologues code for the ion channel responsible for half of background Na(+) -leak conductance in vertebrate and invertebrate neurons. Recessive mutations in human NALCN cause intellectual disability (ID) with hypotonia. Here, we report a de novo heterozygous mutation in NALCN affecting a conserved residue (p.R1181Q) in a girl with ID, episodic and persistent ataxia, and arthrogryposis. Interestingly, her episodes of ataxia were abolished by the administration of acetazolamide, similar to the response observed in episodic ataxia associated with other ion channels. Introducing the analogous mutation in the Caenorhabditis elegans homologue nca-1 induced a coiling locomotion phenotype, identical to that obtained with previously characterized C. elegans gain-of-function nca alleles, suggesting that p.R1181Q confers the same property to NALCN. This observation thus suggests that dominant mutations in NALCN can cause a neurodevelopmental phenotype that overlaps with, while being mostly distinct from that associated with recessive mutations in the same gene.

  11. Pseudotumour Cerebri Presentation in a Child Under the Gonadotropin-Releasing Hormone Agonist Treatment

    PubMed Central

    Gül, Ülkü; Kaçar Bayram, Ayşe; Kendirci, Mustafa; Hatipoğlu, Nihal; Okdemir, Deniz; Gümüş, Hakan; Kurtoğlu, Selim

    2016-01-01

    Gonadotropin-releasing hormone analogues are common treatment option in central precocious puberty in childhood as well as in endometriosis, infertility, and prostate cancer in adults. Pseudotumor cerebri is a rare side effect observed in adults. We present the case of a girl with precocious puberty treated with triptorelin acetate who developed pseudotumor cerebri after the 4th dose. She had headaches, and her blood pressure was detected to be above the 99 percentile. There were no causes underlying of hypertension such as cardiac, renal, or endocrine. Neurological examination was normal except bilateral papilledema. Cranial magnetic resonance imaging was normal. Cerebrospinal fluid (CSF) opening pressure was elevated. Triptorelin therapy was ceased and acetazolamide was applied; CSF pressure returned to normal. We observed pseudotumor cerebri after precocious puberty treatment, a finding for the first time ever seen in childhood. PMID:27087351

  12. A case of recurrent status epilepticus and successful management with progesterone.

    PubMed

    Ramanujam, Bhargavi; Arora, Amit; Malhotra, Varun; Dash, Deepa; Mehta, Santosh; Tripathi, Manjari

    2016-03-01

    Catamenial epilepsy (CE) is a commonly observed phenomenon among women with epilepsy, the management of which is both hormonal and non-hormonal. Progesterone therapy has been tried in these patients, as the possible mechanism of CE is withdrawal of progesterone and a higher oestrogen/progesterone ratio in the perimenstrual and periovulatory periods. Here, we describe a 24-year-old lady with multiple seizure types since childhood, which were refractory to adequate antiepileptic drug therapy after menarche with catamenial clustering of seizures. She went on to have several episodes of non-convulsive status epilepticus also with similar periodicity, which would abate only with midazolam infusion, without the need for ventilatory support. She was tried on acetazolamide, progesterone vaginal pessaries, and maximum tolerated doses of antiepileptic medications, but finally responded to intramuscular and oral progesterone, and has been seizure-free for more than a year.

  13. Intracerebroventricular Infusion of Angiotensin-(1-7) Ameliorates Cognitive Impairment and Memory Dysfunction in a Mouse Model of Alzheimer's Disease.

    PubMed

    Uekawa, Ken; Hasegawa, Yu; Senju, Satoru; Nakagata, Naomi; Ma, Mingjie; Nakagawa, Takashi; Koibuchi, Nobutaka; Kim-Mitsuyama, Shokei

    2016-04-23

    This work was performed to test our hypothesis that angiotensin-(1-7) can ameliorate cognitive impairment and cerebrovascular reactivity in 5XFAD mice, a useful model of Alzheimer's disease. 5XFAD mice received intracerebroventricular infusion of (1) vehicle, (2) angiotensin-(1-7), or (3) angiotensin-(1-7)+A779, a specific Mas receptor antagonist, for 4 weeks. Angiotensin-(1-7), through Mas receptor, significantly ameliorated cognitive impairment in 5XFAD mice. As estimated by acetazolamide-induced increase in cerebral blood flow, angiotensin-(1-7), through Mas receptor, enhanced cerebrovascular reactivity in 5XFAD mice. In conclusion, angiotensin-(1-7)/Mas receptor axis improves cognitive function and cerebrovascular function in a mouse model of Alzheimer's disease.

  14. Neuro-Ophthalmological Manifestations after Intramuscular Medroxyprogesterone: A Forme Fruste of Idiopathic Intracranial Hypertension?

    PubMed Central

    Bahall, Mandreker; Reyes, Antonio Jose; Ramcharan, Kanterpersad; Hosein, Nadeem; Seegobin, Karan; Bahall, Krishni; Sharma, Hiranyadeva; Dhansingh, Stephanie; Mahabir, Amanda

    2016-01-01

    We report a case of a 22-year-old female student nurse who presented to hospital with an acute neuro-ophthalmological syndrome characterized by papilledema, ataxia, ophthalmoplegia and headache after a single first time use of 150 mg medroxyprogesterone intramuscular injection. Clinical, laboratory, radiological and ophthalmological investigations were in keeping with the diagnosis of idiopathic intracranial hypertension but lumbar puncture did not show a raised cerebrospinal fluid pressure suggesting a forme fruste of this entity. Her neuro-ophthalmological clinical features responded well to acetazolamide and diagnostic/therapeutic lumbar puncture. Full recovery was achieved three months after medroxyprogesterone usage. Health care providers must be aware of this adverse drug reaction. PMID:27761224

  15. A 17-year-old male with pseudotumor cerebri secondary to performance-enhancing steroids triggering venous thrombosis in the brain.

    PubMed

    DeSena, Allen D; Weimer, Stephen

    2009-03-01

    This article is a case report of a 17-year-old male who presented with a headache and blurry vision. He subsequently was noted to have papilledema on a fundoscopic examination and an initial normal magnetic resonance imaging and computed tomography of his head; his condition was, therefore, diagnosed as pseudotumor cerebri. A subsequent magnetic resonance venography of his head revealed venous thrombosis, and other investigations revealed an elevated factor VIII level as well as a mutation at the MTHFR locus, consistent with an elevated risk for hypercoagulability. In addition, he admitted to steroid usage for purposes of performance enhancement in baseball. The patient's condition eventually improved with acetazolamide and serial lumbar punctures. Steroids have been linked to predisposition to hypercoagulable states, but there are no reports identified by these authors that link performance-enhancing steroids with pseudotumor cerebri as a result of a coagulation dyscrasia.

  16. Enhanced algal CO(2) sequestration through calcite deposition by Chlorella sp. and Spirulina platensis in a mini-raceway pond.

    PubMed

    Ramanan, Rishiram; Kannan, Krishnamurthi; Deshkar, Ashok; Yadav, Raju; Chakrabarti, Tapan

    2010-04-01

    Biological CO(2) sequestration using algal reactors is one of the most promising and environmentally benign technologies to sequester CO(2). This research study was taken up to alleviate certain limitations associated with the technology such as low CO(2) sequestration efficiency and low biomass yields. The study demonstrates an increase in CO(2) sequestration efficiency by maneuvering chemically aided biological sequestration of CO(2). Chlorella sp. and Spirulina platensis showed 46% and 39% mean fixation efficiency, respectively, at input CO(2) concentration of 10%. The effect of acetazolamide, a potent carbonic anhydrase inhibitor, on CO(2) sequestration efficiency was studied to demonstrate the role of carbonic anhydrase in calcite deposition. Calcite formed by both species was characterized by scanning electron microscopy coupled electron dispersive spectroscopy and X-ray diffraction. The overall scheme of calcite deposition coupled CO(2) fixation with commercially utilizable biomass as a product seems a viable option in the efforts to sequester increasing CO(2) emissions.

  17. [HYPP--hyperkalemic periodic paralysis in horses].

    PubMed

    Zeilmann, M

    1993-12-01

    A literature review of the clinical syndrome HYPP (Hyperkalemic periodic paralysis) affecting Quarter Horses is given. HYPP is characterized by sporadic attacks of muscle tremors, weakness and/or collapse, lasting for variable periods of time. Diagnosis is based on physical findings in association with hyperkalemia. In horses with HYPP, the regulation of ion transport through the sodium channels in the muscle cells occasionally fails, causing uncontrollable muscle twitching. Further investigations into molecular genetics reveals a mutation in the gene responsible for sodium and potassium regulation. The identification of this gene mutation is the basis for the blood test used to diagnose HYPP. HYPP is inherited as an autosomal dominant trait. Treatment of HYPP attacks by intravenous application of calcium gluconate, bicarbonate and glucose results in rapid recovery. Consequent dietary management and daily administration of acetazolamide effectively controls the disease.

  18. Synthesis of bulky-tailed sulfonamides incorporating pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidin-1(5H)-yl) moieties and evaluation of their carbonic anhydrases I, II, IV and IX inhibitory effects.

    PubMed

    Fares, Mohamed; Eladwy, Radwa A; Nocentini, Alessio; El Hadi, Soha R Abd; Ghabbour, Hazem A; Abdel-Megeed, Ashraf; Eldehna, Wagdy M; Abdel-Aziz, Hatem A; Supuran, Claudiu T

    2017-04-01

    Using celecoxib as lead, two novel series of sulfonamides incorporating the pyridotriazolopyrimidine scaffold have been synthesized and evaluated in vitro as inhibitors against four relevant human (h) carbonic anhydrases (CAs, EC 4.2.1.1), the cytosolic and ubiquitous hCA I and II as well as the transmembrane hCA IV and hCA IX. Most of the reported sulfonamides acted as efficient, low micromolar inhibitors of hCAI, II and IV, whereas they displayed higher efficacy in inhibiting the tumor-associated isoform hCA IX. Many derivates herein reported showed better hCA IX versus hCA II selectivity ratios compared to celecoxib or acetazolamide. Considering isoform IX is a validated target for the diagnosis and treatment of hypoxic tumors, discovery of selective CA IX inhibitors represents a promising step to unveil more effective anticancer therapies.

  19. Drug Use on Mont Blanc: A Study Using Automated Urine Collection

    PubMed Central

    Robach, Paul; Trebes, Gilles; Lasne, Françoise; Buisson, Corinne; Méchin, Nathalie; Mazzarino, Monica; de la Torre, Xavier; Roustit, Matthieu; Kérivel, Patricia; Botré, Francesco; Bouzat, Pierre

    2016-01-01

    Mont Blanc, the summit of Western Europe, is a popular but demanding high-altitude ascent. Drug use is thought to be widespread among climbers attempting this summit, not only to prevent altitude illnesses, but also to boost physical and/or psychological capacities. This practice may be unsafe in this remote alpine environment. However, robust data on medication during the ascent of Mont Blanc are lacking. Individual urine samples from male climbers using urinals in mountain refuges on access routes to Mont Blanc (Goûter and Cosmiques mountain huts) were blindly and anonymously collected using a hidden automatic sampler. Urine samples were screened for a wide range of drugs, including diuretics, glucocorticoids, stimulants, hypnotics and phosphodiesterase 5 (PDE-5) inhibitors. Out of 430 samples analyzed from both huts, 35.8% contained at least one drug. Diuretics (22.7%) and hypnotics (12.9%) were the most frequently detected drugs, while glucocorticoids (3.5%) and stimulants (3.1%) were less commonly detected. None of the samples contained PDE-5 inhibitors. Two substances were predominant: the diuretic acetazolamide (20.6%) and the hypnotic zolpidem (8.4%). Thirty three samples were found positive for at least two substances, the most frequent combination being acetazolamide and a hypnotic (2.1%). Based on a novel sampling technique, we demonstrate that about one third of the urine samples collected from a random sample of male climbers contained one or several drugs, suggesting frequent drug use amongst climbers ascending Mont Blanc. Our data suggest that medication primarily aims at mitigating the symptoms of altitude illnesses, rather than enhancing performance. In this hazardous environment, the relatively high prevalence of hypnotics must be highlighted, since these molecules may alter vigilance. PMID:27253728

  20. A new method for measuring dynamic change of tracer distribution using dynamic single photon emission tomography with a slip-ring rotational gamma camera.

    PubMed

    Miyazaki, Y; Hashimoto, M; Kinuya, S; Murata, Y; Inoue, H; Shiozaki, J; Takimoto, M; Yoshioka, K; Nakajima, K; Taki, J

    2002-11-01

    The clinical applicability of dynamic single photon emission tomograpy (SPET) using a dual-head gamma camera equipped with a slip-ring rotational mechanism, referred to as serial SPET, was examined in the present investigation. Serial SPET enables the production of tomographic images for any arbitrary time frame from an arbitrary range of data to 360 degrees. In a pre-clinical evaluation, a correlation between radioactivity concentration and serial SPET counts was evaluated in a phantom with continuous changes in 99mTc concentration. A differential value was obtained from each pair of SPET images; moreover, moving average approximation processing was investigated with respect to the elimination of noise in the data. In 11 and one patient presenting with cerebrovascular disease and meningioma, respectively, changes in SPET counts were evaluated when 99mTc ethyl cysteinate dimer (99mTc-ECD) was continuously administered at a constant rate in the resting state. Furthermore, in six of 11 subjects with cerebrovascular disease, changes occurring in SPET counts were examined by using acetazolamide loading while continuously administering 99mTc-ECD at a constant rate. Consequently, serial SPET enabled the evaluation of changes in radioactivity concentration over time in both the phantom and preliminary clinical studies. Data analysis by differential processing utilizing moving average approximation processing enabled the detection of minor changes in radioactivity concentration. An increase of 15.1+/-5.4% was observed in SPET counts of the unaffected cerebral hemisphere with acetazolamide loading. The response of the affected hemisphere was less prominent. These findings suggest that serial SPET would be an effective technique for the pharmacokinetic analysis of radiopharmaceuticals.

  1. Positron emission tomography/magnetic resonance hybrid scanner imaging of cerebral blood flow using (15)O-water positron emission tomography and arterial spin labeling magnetic resonance imaging in newborn piglets.

    PubMed

    Andersen, Julie B; Henning, William S; Lindberg, Ulrich; Ladefoged, Claes N; Højgaard, Liselotte; Greisen, Gorm; Law, Ian

    2015-11-01

    Abnormality in cerebral blood flow (CBF) distribution can lead to hypoxic-ischemic cerebral damage in newborn infants. The aim of the study was to investigate minimally invasive approaches to measure CBF by comparing simultaneous (15)O-water positron emission tomography (PET) and single TI pulsed arterial spin labeling (ASL) magnetic resonance imaging (MR) on a hybrid PET/MR in seven newborn piglets. Positron emission tomography was performed with IV injections of 20 MBq and 100 MBq (15)O-water to confirm CBF reliability at low activity. Cerebral blood flow was quantified using a one-tissue-compartment-model using two input functions: an arterial input function (AIF) or an image-derived input function (IDIF). The mean global CBF (95% CI) PET-AIF, PET-IDIF, and ASL at baseline were 27 (23; 32), 34 (31; 37), and 27 (22; 32) mL/100 g per minute, respectively. At acetazolamide stimulus, PET-AIF, PET-IDIF, and ASL were 64 (55; 74), 76 (70; 83) and 79 (67; 92) mL/100 g per minute, respectively. At baseline, differences between PET-AIF, PET-IDIF, and ASL were 22% (P<0.0001) and -0.7% (P=0.9). At acetazolamide, differences between PET-AIF, PET-IDIF, and ASL were 19% (P=0.001) and 24% (P=0.0003). In conclusion, PET-IDIF overestimated CBF. Injected activity of 20 MBq (15)O-water had acceptable concordance with 100 MBq, without compromising image quality. Single TI ASL was questionable for regional CBF measurements. Global ASL CBF and PET CBF were congruent during baseline but not during hyperperfusion.

  2. Evidence from simultaneous intracellular- and surface-pH transients that carbonic anhydrase IV enhances CO2 fluxes across Xenopus oocyte plasma membranes.

    PubMed

    Musa-Aziz, Raif; Occhipinti, Rossana; Boron, Walter F

    2014-11-01

    Human carbonic anhydrase IV (CA IV) is GPI-anchored to the outer membrane surface, catalyzing CO2/HCO3 (-) hydration-dehydration. We examined effects of heterologously expressed CA IV on intracellular-pH (pHi) and surface-pH (pHS) transients caused by exposing oocytes to CO2/HCO3 (-)/pH 7.50. CO2 influx causes a sustained pHi fall and a transient pHS rise; CO2 efflux does the opposite. Both during CO2 addition and removal, CA IV increases magnitudes of maximal rate of pHi change (dpHi/dt)max, and maximal pHS change (ΔpHS) and decreases time constants for pHi changes (τpHi ) and pHS relaxations (τpHS ). Decreases in time constants indicate that CA IV enhances CO2 fluxes. Extracellular acetazolamide blocks all CA IV effects, but not those of injected CA II. Injected acetazolamide partially reduces CA IV effects. Thus, extracellular CA is required for, and the equivalent of cytosol-accessible CA augments, the effects of CA IV. Increasing the concentration of the extracellular non-CO2/HCO3 (-) buffer (i.e., HEPES), in the presence of extracellular CA or at high [CO2], accelerates CO2 influx. Simultaneous measurements with two pHS electrodes, one on the oocyte meridian perpendicular to the axis of flow and one downstream from the direction of extracellular-solution flow, reveal that the downstream electrode has a larger (i.e., slower) τpHS , indicating [CO2] asymmetry over the oocyte surface. A reaction-diffusion mathematical model (third paper in series) accounts for the above general features, and supports the conclusion that extracellular CA, which replenishes entering CO2 or consumes exiting CO2 at the extracellular surface, enhances the gradient driving CO2 influx across the cell membrane.

  3. Role of chloride transport proteins in the vasorelaxant action of nitroprusside in isolated rat aorta.

    PubMed

    Valero, Marta; Pereboom, Désirée; Garay, Ricardo P; Alda, José Octavio

    2006-12-28

    Chloride ions play a key role in smooth muscle contraction, but little is known concerning their role in smooth muscle relaxation. Here we investigated the effect of chloride transport inhibitors on the vasorelaxant responses to nitroprusside in isolated and endothelium-denuded rat aorta, precontracted with phenylephrine 1 muM. Incubation of aortic rings in NO(3)(-) media strongly potentiated the vasorelaxant responses to nitroprusside. Bumetanide, DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) and acetazolamide strongly potentiated the vasorelaxant responses to nitroprusside (by 70-100%). EC(50) were 2.3+/-0.5 microM for bumetanide, 26+/-15 microM for DIDS and 510+/-118 microM for acetazolamide (n=6 for condition). Niflumic acid, a selective inhibitor of ClCa (calcium-activated chloride channels), potentiated nitroprusside relaxation to a similar extent as chloride transport inhibitors, in a non-additive manner. Zinc and nickel ions, both modestly potentiated nitroprusside vasorelaxation (by 20-30%). Cobaltum had negligible effect on nitroprusside vasorelaxation. CPA (p-chlorophenoxy-acetic acid), an inhibitor of volume-sensitive chloride channels (ClC), slightly potentiated nitroprusside vasorelaxation (by 15%), and the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel inhibitors CFTR(inh)172 (5-[(4-Carboxyphenyl)methylene]-2-thioxo-3-[(3-trifluoromethyl)phenyl-4-thiazolidinone), DPC (diphenylamine-2,2'-dicarboxylic acid) and glibenclamide were without significant effect. In conclusion, inhibition of chloride transport proteins strongly potentiates the vasorelaxant responses to nitroprusside in isolated rat aorta. This effect seems mediated by chloride depletion and inhibition of a chloride channel activated by both, calcium and cyclic GMP (cGMP).

  4. Quantifying the ventilatory control contribution to sleep apnoea using polysomnography.

    PubMed

    Terrill, Philip I; Edwards, Bradley A; Nemati, Shamim; Butler, James P; Owens, Robert L; Eckert, Danny J; White, David P; Malhotra, Atul; Wellman, Andrew; Sands, Scott A

    2015-02-01

    Elevated loop gain, consequent to hypersensitive ventilatory control, is a primary nonanatomical cause of obstructive sleep apnoea (OSA) but it is not possible to quantify this in the clinic. Here we provide a novel method to estimate loop gain in OSA patients using routine clinical polysomnography alone. We use the concept that spontaneous ventilatory fluctuations due to apnoeas/hypopnoeas (disturbance) result in opposing changes in ventilatory drive (response) as determined by loop gain (response/disturbance). Fitting a simple ventilatory control model (including chemical and arousal contributions to ventilatory drive) to the ventilatory pattern of OSA reveals the underlying loop gain. Following mathematical-model validation, we critically tested our method in patients with OSA by comparison with a standard (continuous positive airway pressure (CPAP) drop method), and by assessing its ability to detect the known reduction in loop gain with oxygen and acetazolamide. Our method quantified loop gain from baseline polysomnography (correlation versus CPAP-estimated loop gain: n=28; r=0.63, p<0.001), detected the known reduction in loop gain with oxygen (n=11; mean±sem change in loop gain (ΔLG) -0.23±0.08, p=0.02) and acetazolamide (n=11; ΔLG -0.20±0.06, p=0.005), and predicted the OSA response to loop gain-lowering therapy. We validated a means to quantify the ventilatory control contribution to OSA pathogenesis using clinical polysomnography, enabling identification of likely responders to therapies targeting ventilatory control.

  5. CAUSES AND CONSEQUENCES OF ZINC DYSHOMEOSTASIS IN RATS WITH CHRONIC ALDOSTERONISM

    PubMed Central

    Gandhi, Malay S.; Deshmukh, Prajwal A.; Kamalov, German; Zhao, Tieqiang; Zhao, Wenyuan; Whaley, Jonathan T.; Tichy, Jill R.; Bhattacharya, Syamal K.; Ahokas, Robert A.; Sun, Yao; Gerling, Ivan C.; Weber, Karl T.

    2009-01-01

    Iterations in Ca2+ and Mg2+ balance accompany aldosteronism (inappropriate for dietary Na+ intake). Increased Zn excretion and Zn translocation to injured tissues, including the heart, also occurs. Several causes and consequences of Zn dyshomeostasis in rats receiving aldosterone/salt treatment (ALDOST) were examined: 1) the role of urinary acidification in promoting hyperzincuria, acetazolamide (75 mg/kg), a carbonic anhydrase inhibitor, was used as cotreatment to raise urinary HCO3− excretion; 2) assess Zn levels in the heart, including cardiomyocyte cytosolic free [Zn2+]i and mitochondrial Zn, the expression of metallothionein (MT-I), a Zn binding protein, and biomarkers of oxidative stress; and 3) monitor oxidative stress and cardiac pathology in response to ZnSO4 supplement (40 mg/day). Compared to controls, at 4 wks ALDOST we found: an acidification of urine and metabolic alkalosis associated with increased urinary Zn excretion and hypozincemia, each of which were prevented by acetazolamide; a rise in cardiac Zn including increased [Zn2+]i and mitochondrial Zn, associated with increased tissue MT-I, 8-isoprostane, malondialdehyde, and gp91phox, coupled with oxidative stress in plasma and urine; and ZnSO4 prevented hypozincemia, but not ionized hypocalcemia, and attenuated oxidative stress and microscopic scarring without preventing the vasculitis and perivascular fibrosis of intramural coronary arteries. Thus, the hyperzincuria seen with ALDOST is due to urinary acidification. The oxidative stress that appears in the heart is accompanied by increased tissue Zn serving as an antioxidant. Cotreatment with ZnSO4 attenuated cardiomyocyte necrosis, however, polynutrient supplement may be required to counteract the dyshomeostasis of all 3 cations that accompanies aldosteronism and contribute to cardiac pathology. PMID:18806605

  6. Drug Use on Mont Blanc: A Study Using Automated Urine Collection.

    PubMed

    Robach, Paul; Trebes, Gilles; Lasne, Françoise; Buisson, Corinne; Méchin, Nathalie; Mazzarino, Monica; de la Torre, Xavier; Roustit, Matthieu; Kérivel, Patricia; Botré, Francesco; Bouzat, Pierre

    2016-01-01

    Mont Blanc, the summit of Western Europe, is a popular but demanding high-altitude ascent. Drug use is thought to be widespread among climbers attempting this summit, not only to prevent altitude illnesses, but also to boost physical and/or psychological capacities. This practice may be unsafe in this remote alpine environment. However, robust data on medication during the ascent of Mont Blanc are lacking. Individual urine samples from male climbers using urinals in mountain refuges on access routes to Mont Blanc (Goûter and Cosmiques mountain huts) were blindly and anonymously collected using a hidden automatic sampler. Urine samples were screened for a wide range of drugs, including diuretics, glucocorticoids, stimulants, hypnotics and phosphodiesterase 5 (PDE-5) inhibitors. Out of 430 samples analyzed from both huts, 35.8% contained at least one drug. Diuretics (22.7%) and hypnotics (12.9%) were the most frequently detected drugs, while glucocorticoids (3.5%) and stimulants (3.1%) were less commonly detected. None of the samples contained PDE-5 inhibitors. Two substances were predominant: the diuretic acetazolamide (20.6%) and the hypnotic zolpidem (8.4%). Thirty three samples were found positive for at least two substances, the most frequent combination being acetazolamide and a hypnotic (2.1%). Based on a novel sampling technique, we demonstrate that about one third of the urine samples collected from a random sample of male climbers contained one or several drugs, suggesting frequent drug use amongst climbers ascending Mont Blanc. Our data suggest that medication primarily aims at mitigating the symptoms of altitude illnesses, rather than enhancing performance. In this hazardous environment, the relatively high prevalence of hypnotics must be highlighted, since these molecules may alter vigilance.

  7. The history and rationale of using carbonic anhydrase inhibitors in the treatment of peptic ulcers. In memoriam Ioan Puşcaş (1932-2015).

    PubMed

    Buzás, György M; Supuran, Claudiu T

    2016-08-01

    Carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) started to be used in the treatment of peptic ulcers in the 1970s, and for more than two decades, a group led by Ioan Puşcaş used them for this purpose, assuming that by inhibiting the gastric mucosa CA isoforms, hydrochloric acid secretion is decreased. Although acetazolamide and other sulfonamide CAIs are indeed effective in healing ulcers, the inhibition of CA isoforms in other organs than the stomach led to a number of serious side effects which made this treatment obsolete when the histamine H2 receptor antagonists and the proton pump inhibitors became available. Decades later, in 2002, it has been discovered that Helicobacter pylori, the bacterial pathogen responsible for gastric ulcers and cancers, encodes for two CAs, one belonging to the α-class and the other one to the β-class of these enzymes. These enzymes are crucial for the life cycle of the bacterium and its acclimation within the highly acidic environment of the stomach. Inhibition of the two bacterial CAs with sulfonamides such as acetazolamide, a low-nanomolar H. pylori CAI, is lethal for the pathogen, which explains why these compounds were clinically efficient as anti-ulcer drugs. Thus, the approach promoted by Ioan Puşcaş for treating this disease was a good one although the rationale behind it was wrong. In this review, we present a historical overview of the sulfonamide CAIs as anti-ulcer agents, in memoriam of the scientist who was in the first line of this research trend.

  8. Effectiveness of spray congealing to obtain physically stabilized amorphous dispersions of a poorly soluble thermosensitive API.

    PubMed

    Kulthe, Viraj Vitthal; Chaudhari, Pravin Digambar

    2014-12-01

    An amorphous phase produced by micronization up to the molecular or colloidal level of a poorly soluble drug having low lipophilicity can distinctly enhance its solubility characteristics. However, though dispersing the molten mass of a poorly water-soluble drug within polymeric matrix has been found to be most effective in formation of molecular dispersions, the drug molecules which melt at high temperature also accompanied by decomposition, such as acetazolamide, are difficult to formulate as molecular dispersions. Hence, a method is proposed to obtain molecular dispersions of acetazolamide with poloxamer-237 by spray congealing under optimal heat treatment. Uniform molecular and/or colloidal dispersions of the drug were achieved with instantaneous solvent evaporation by mixing a drug solution with molten mass of the plasticizer matrix. Immobilization of dispersed drug molecules was effected subsequently through rapid solidification by spray congealing. Initial characterization of 1:1, 1:1.5, and 1:2 ratios of solid dispersions and devitrification study of an optimized (1:2) ratio ensured efficacy of the proposed method in formation of physically stabilized amorphous systems without thermal degradation and hence resulted in more than ninefold rise in solubility and more than 90% dissolution within initial 10 min. With 1:2 ratio, molecular dispersions could be achieved by initial solvent evaporation stage, which when subjected to spray congealing produced physically stable amorphous systems, without signs of thermal degradation. This study also proposes an opportunity for selection of those polymers with which the drug is immiscible in their fluid state, yet obtaining molecular dispersions.

  9. Involvement of AQP 1 in the cardio-protective effect of remifentanil post-conditioning in ischemia/reperfusion rats

    PubMed Central

    Lin, Peng-Tao; Chen, Wen-Hua; Zheng, Hong; Lai, Zhong-Meng; Zhang, Liang-Cheng

    2015-01-01

    Background: our research aim to study the role of AQP1 in the cardioprotective effect of remifentanil post-conditioning for myocardial ischemia/reperfusion injury. Methods: Ninety Sprague-Dawley (SD) rats were divided into 6 groups: sham operation group (Sham group), myocardial ischemia and reperfusion group (I/R group), postconditioning of remifentanil group (R-post), postconditioning of remifentanil plus AQP1 inhibitor acetazolamide group (R-post +Ace), postconditioning of remifentanil plus opioid-receptor antagonist compounds (R-post +AC), postconditioning of remifentanil plus AQP1 enhancer arginine vasopressin (R-post +AV). All groups except the sham operation group were given 30 min ischemia in left anterior descending (LAD) coronary arteries. All groups were then given 120 min reperfusion to the LAD. Before reperfusion, the R-post, R-post +Ace, R-post +AC, R-post +AV groups were given 10 min remifentanil post-conditioning. Hemodynamic data were measured every 30 min after initiation of ischemia. The rats’ hearts were exercised for detecting infarct size and water content in the left ventricle, and AQP1 expression were also detected. Results: The R-post group showed a significant reduction of the infarct size compared to the I/R group. The effect of R-post for reducing infarct size was slightly enhanced by adding acetazolamide to R-post, so significant differences could still be found when compared R-post+Ace group to the I/R group. The effect of infarct size reduction brought by R-post was blocked by the opioid-receptor antagonist compounds. This effect was also blocked by the AQP1 enhancer. Similar outcomes were found considering the water content of the left ventricle and the AQP1 expression. Conclusion: Cardioprotective effect of remifentanil post-conditioning may initiate through inhibiting the function of AQP1. PMID:26550187

  10. Ionic mechanisms of Ca(2+)-dependent electrolyte transport across equine sweat gland epithelium.

    PubMed

    Ko, W H; Chan, H C; Chew, S B; Wong, P Y

    1996-06-15

    1. The ionic mechanism involved in Ca(2+)-stimulated electrolyte transport in cultured equine sweat gland epithelial cells was studied using the short-circuit current (ISC) technique. 2. Microscopy revealed that the cultured cells grown on Millipore filters formed polarized monolayers with tight junctions. Monolayers exhibited a mean transepithelial resistance of 333.9 +/- 40.4 omega cm2. 3. Ca(2+)-mobilizing agents, A23187 (1 microM) or thapsigargin (0.01-1 microM), stimulated ISC while forskolin exerted little effect on the ISC. 4. Replacement of external Cl- by gluconate significantly reduced the ISC by 63% when stimulated by 0.1 microM thapsigargin. Residual ISC could be abolished (> 99%) by elimination of HCO3- from the bathing solution. 5. Basolateral addition of bumetanide (0.1 mM), ouabain (0.01 mM) and acetazolamide (45 microM) and apical addition of methyl isobutyl amiloride (MIA, 1-100 microM) all had inhibitory effects on the thapsigargin-stimulated ISC to various extents. 6. Substantial current inhibition could be obtained using 4, 4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and diphenylamine-2-carboxylate (DPC) in a concentration-dependent manner. 7. The K+ channel blocker barium (5 mM) was effective on both sides of the epithelium with a much larger effect on the basolateral side. 8. The inhibitory effects of acetazolamide, amiloride, MIA, DIDS and DPC on the thapsigargin-stimulated ISC were also observed when a Cl(-)-free solution was used. 9. The results provide evidence for Ca(2+)-stimulated HCO3- as well as Cl- secretion by equine sweat gland epithelium.

  11. Quantitative cerebral blood flow measurements in the rat using a beta-probe and H2 15O.

    PubMed

    Weber, Bruno; Späth, Nicolas; Wyss, Matthias; Wild, Damian; Burger, Cyrill; Stanley, Ross; Buck, Alfred

    2003-12-01

    Beta-probes are a relatively new tool for tracer kinetic studies in animals. They are highly suited to evaluate new positron emission tomography tracers or measure physiologic parameters at rest and after some kind of stimulation or intervention. In many of these experiments, the knowledge of CBF is highly important. Thus, the purpose of this study was to evaluate the method of CBF measurements using a beta-probe and H2 15O. CBF was measured in the barrel cortex of eight rats at baseline and after acetazolamide challenge. Trigeminal nerve stimulation was additionally performed in five animals. In each category, three injections of 250 to 300 MBq H2 15O were performed at 10-minute intervals. Data were analyzed using a standard one-tissue compartment model (K1 = CBF, k2 = CBF/p, where p is the partition coefficient). Values for K1 were 0.35 +/- 0.09, 0.58 +/- 0.16, and 0.49 +/- 0.03 mL x min(-1) x mL(-1) at rest, after acetazolamide challenge, and during trigeminal nerve stimulation, respectively. The corresponding values for k2 were 0.55 +/- 0.12, 0.94 +/- 0.16, and 0.85 +/- 0.12 min(-7), and for p were 0.64 +/- 0.05, 0.61 +/- 0.07, and 0.59 +/- 0.06. The standard deviation of the difference between two successive experiments, a measure for the reproducibility of the method, was 10.1%, 13.0%, and 5.7% for K1, k2, and p, respectively. In summary, beta-probes in conjunction with H2 15O allow the reproducible quantitative measurement of CBF, although some systematic underestimation seems to occur, probably because of partial volume effects.

  12. Evidence from simultaneous intracellular- and surface-pH transients that carbonic anhydrase II enhances CO2 fluxes across Xenopus oocyte plasma membranes

    PubMed Central

    Occhipinti, Rossana; Boron, Walter F.

    2014-01-01

    The α-carbonic anhydrases (CAs) are zinc-containing enzymes that catalyze the interconversion of CO2 and HCO3−. Here, we focus on human CA II (CA II), a ubiquitous cytoplasmic enzyme. In the second paper in this series, we examine CA IV at the extracellular surface. After microinjecting recombinant CA II in a Tris solution (or just Tris) into oocytes, we expose oocytes to 1.5% CO2/10 mM HCO3−/pH 7.50 while using microelectrodes to monitor intracellular pH (pHi) and surface pH (pHS). CO2 influx causes the familiar sustained pHi fall as well as a transient pHS rise; CO2 efflux does the opposite. Both during CO2 addition and removal, CA II increases the magnitudes of the maximal rate of pHi change, (dpHi/dt)max, and the maximal change in pHS, ΔpHS. Preincubating oocytes with the inhibitor ethoxzolamide eliminates the effects of CA II. Compared with pHS, pHi begins to change only after a delay of ∼9 s and its relaxation has a larger (i.e., slower) time constant (τpHi > τpHS). Simultaneous measurements with two pHi electrodes, one superficial and one deep, suggest that impalement depth contributes to pHi delay and higher τpHi. Using higher CO2/HCO3− levels, i.e., 5%/33 mM HCO3− or 10%/66 mM HCO3−, increases (dpHi/dt)max and ΔpHS, though not in proportion to the increase in [CO2]. A reaction-diffusion mathematical model (described in the third paper in this series) accounts for the above general features and supports the conclusion that cytosolic CA—consuming entering CO2 or replenishing exiting CO2—increases CO2 fluxes across the cell membrane. PMID:24965587

  13. Mechanisms of transepithelial ammonia excretion and luminal alkalinization in the gut of an intestinal air-breathing fish, Misgurnus anguilliacaudatus.

    PubMed

    Wilson, Jonathan M; Moreira-Silva, Joana; Delgado, Inês L S; Ebanks, Sue C; Vijayan, Mathilakath M; Coimbra, João; Grosell, Martin

    2013-02-15

    The weatherloach, Misgurnus angulliacaudatus, is an intestinal air-breathing, freshwater fish that has the unique ability to excrete ammonia through gut volatilization when branchial and cutaneous routes are compromised during high environmental ammonia or air exposure. We hypothesized that transepithelial gut NH(4)(+) transport is facilitated by an apical Na(+)/H(+) (NH(4)(+)) exchanger (NHE) and a basolateral Na(+)/K(+)(NH(4)(+))-ATPase, and that gut boundary layer alkalinization (NH(4)(+) → NH(3) + H(+)) is facilitated by apical HCO(3)(-) secretion through a Cl(-)/HCO(3)(-) anion exchanger. This was tested using a pharmacological approach with anterior (digestive) and posterior (respiratory) intestine preparations mounted in pH-stat-equipped Ussing chambers. The anterior intestine had a markedly higher conductance, increased short-circuit current, and greater net base (J(base)) and ammonia excretion rates (J(amm)) than the posterior intestine. In the anterior intestine, HCO(3)(-) accounted for 70% of J(base). In the presence of an imposed serosal-mucosal ammonia gradient, inhibitors of both NHE (EIPA, 0.1 mmol l(-1)) and Na(+)/K(+)-ATPase (ouabain, 0.1 mmol l(-1)) significantly inhibited J(amm) in the anterior intestine, although only EIPA had an effect in the posterior intestine. In addition, the anion exchange inhibitor DIDS significantly reduced J(base) in the anterior intestine although only at a high dose (1 mmol l(-1)). Carbonic anhydrase does not appear to be associated with gut alkalinization under these conditions as ethoxzolamide was without effect on J(base). Membrane fluidity of the posterior intestine was low, suggesting low permeability, which was also reflected in a lower mucosal-serosal J(amm) in the presence of an imposed gradient, in contrast to that in the anterior intestine. To conclude, although the posterior intestine is highly modified for gas exchange, it is the anterior intestine that is the likely site of ammonia excretion and

  14. The intraocular pressure-lowering properties of intravenous paracetamol

    PubMed Central

    van den Heever, Henning; Meyer, David

    2016-01-01

    Aim The aim of this paper was to investigate the intraocular pressure (IOP)-changing properties of a single standard dose of intravenous (IV) paracetamol and compare it to that of topical timolol, oral acetazolamide, and no treatment. Methods A prospective, randomized, investigator-blind, parallel-group study was conducted in 73 eyes of 52 subjects. Subjects received a single dose of IV paracetamol (1 g), oral acetazolamide (250 mg), topical timolol (0.5%, one drop), or no treatment. Baseline IOP was measured, and the measurement was repeated at 1, 2, 4, and 6 hours after treatment. Results Paracetamol reduced IOP from baseline by −10.8% (95% confidence interval [CI]: −4.9% to −16.8%, P=0.146) at 1 hour, −13.3% (95% CI: −8.3% to −18.4%, P=0.045) at 2 hours, −11.8% (95% CI: −5.5% to −18.4%, P=1.000) at 4 hours, and −23.9% (95% CI: −17.8% to −30.1%, P=0.006) at 6 hours after treatment. In the no-treatment group, the change was −2.9% (95% CI: +1.0% to −6.7%, P= referent) at 1 hour, −2.1% (95% CI: +2.9% to −7.2%, P= referent) at 2 hours, −7.6% (95% CI: −3.9% to −11.2%, P= referent) at 4 hours, and −6.9% (95% CI: −3.6% to −10.2%, P= referent) at 6 hours. Acetazolamide reduced IOP by −18.8% (95% CI: −12.7% to −24.8%, P=0.000) at 1 hour, −26.2% (95% CI: −18.2% to −34.2%, P=0.001) at 2 hours, −24.6% (95% CI: −16.9% to −32.3%, P=0.000) after 4 hours, and −26.9% (95% CI: −19.6% to −34.3%, P=0.000) 6 hours after treatment. Timolol reduced IOP by −31.2% (95% CI: −26.7% to −35.7%, P=0.000) at 1 hour, −27.7% (95% CI: −20.7% to −34.8%, P=0.000) at 2 hours, −28.7% (95% CI: −21.1% to −36.2%, P=0.000) at 4 hours, and −21.3% (95% CI: −13.4% to −30.0%, P=0.030) at 6 hours after treatment. The average change in IOP for the no-treatment group was −4.8% (95% CI: −2.6% to −6.9%, P= referent). It was −15.7% (95% CI: −9.3% to −22.1%, P=0.021) for paracetamol, −23.1% (95% CI: −16.4% to

  15. The Role of Epithelial Sodium Channel ENaC and the Apical Cl-/HCO3- Exchanger Pendrin in Compensatory Salt Reabsorption in the Setting of Na-Cl Cotransporter (NCC) Inactivation

    PubMed Central

    Patel-Chamberlin, Mina; Varasteh Kia, Mujan; Xu, Jie; Barone, Sharon; Zahedi, Kamyar; Soleimani, Manoocher

    2016-01-01

    Background The absence of NCC does not cause significant salt wasting in NCC deficient mice under basal conditions. We hypothesized that ENaC and pendrin play important roles in compensatory salt absorption in the setting of NCC inactivation, and their inhibition and/or downregulation can cause significant salt wasting in NCC KO mice. Methods WT and NCC KO mice were treated with a daily injection of either amiloride, an inhibitor of ENaC, or acetazolamide (ACTZ), a blocker of salt and bicarbonate reabsorption in the proximal tubule and an inhibitor of carbonic anhydrases in proximal tubule and intercalated cells, or a combination of acetazolamide plus amiloride for defined durations. Animals were subjected to daily balance studies. At the end of treatment, kidneys were harvested and examined. Blood samples were collected for electrolytes and acid base analysis. Results Amiloride injection significantly increased the urine output (UO) in NCC KO mice (from 1.3 ml/day before to 2.5 ml/day after amiloride, p<0.03, n = 4) but caused only a slight change in UO in WT mice (p>0.05). The increase in UO in NCC KO mice was associated with a significant increase in sodium excretion (from 0.25 mmol/24 hrs at baseline to 0.35 mmol/24 hrs after amiloride injection, p<0.05, n = 4). Daily treatment with ACTZ for 6 days resulted in >80% reduction of kidney pendrin expression in both WT and NCC KO mice. However, ACTZ treatment noticeably increased urine output and salt excretion only in NCC KO mice (with urine output increasing from a baseline of 1.1 ml/day to 2.3 ml/day and sodium excretion increasing from 0.22 mmole/day before to 0.31 mmole/day after ACTZ) in NCC KO mice; both parameters were significantly higher than in WT mice. Western blot analysis demonstrated significant enhancement in ENaC expression in medulla and cortex of NCC KO and WT mice in response to ACTZ injection for 6 days, and treatment with amiloride in ACTZ-pretreated mice caused a robust increase in salt

  16. Study on the cerebrovascular reserve capacity by MR perfusion weighted imaging in SHR

    NASA Astrophysics Data System (ADS)

    Zhou, Quan; Dong, Yang; Chen, WenLi; Lin, Xueying; Xing, Da; Huang, Li

    2007-05-01

    Cerebrovascular disease is one of the leading causes of death, and approximately 50% of survivors have a residual neurologic deficit and greater than 25% require chronic care. Cerebrovascular reserve capacity (CVRC) describes how far cerebral perfusion can increase from a baseline value after stimulation. High blood pressure is the most important independent risk factor for stroke and other vascular diseases. The incidence of stroke in the hypertensive is six times higher than in the patient with normal blood pressure. CVRC in the hypertensive was even lower than in control patients. MR perfusion weighted imaging (MR PWI) with the well-established acetazolamide (ACZ) stimulation test has been used for assessing brain function. The aim of this work is to assess the cerebrovascular reserve capacity by MR PWI with "ACZ" tolerance test in spontaneous hypertensive rat (SHR) and to identify its value in evaluating the CVRC. Experimental animal including 3 groups: Wistar-Kyoto rats (WKY) (12-week-old) as control group, SHR (12-week-old and 20-week-old) as experimental group. MR PWI was performed respectively before and after acetazolamide administrated orally in 3 groups on a clinical 1.5 Tesla GE Signa MR fx/i whole-body MR system. The ROI was chosen in the bilateral frontal lobe to measure the value of rCBV, rCBF and MTT. The results showed that before ACZ-test, there was statistic differences between the WKY and SHR(12-week-old), and between SHR(12-week-old) and SHR(20-week-old) in the values of rCBV and rCBF (P>0.05), and after ACZ-test, there were statistic differences between WKY and SHR (20-week-old), and between SHR(12-week-old) and SHR(20-week-old) in the rCBV value (P<0.05). It is concluded that the method of MRI PWI combined with the "ACZ stress test" can provide more qualitative and half-quantitative information on the cerebral perfusion to evaluate the CVRC in SHR.

  17. Papilledema Outcomes from the OCT Substudy of the Idiopathic Intracranial Hypertension Treatment Trial

    PubMed Central

    2015-01-01

    Objective To assess treatment efficacy using spectral domain optical coherence tomography (SD-OCT) measurements of papilledema in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT), which evaluated the effects of acetazolamide (ACZ) and weight management and placebo and weight management in eyes with mild visual loss. Design Randomized double-masked control clinical trial of acetazolamide (ACZ) plus weight management compared with placebo plus weight management in previously untreated III in subjects withmild visual field loss. Subjects Eighty-nine (43 ACZ, 46 placebo treated) of 165 subject meeting entry criteria for the IIHTT. Methods Subjects had perimetry, papilledema grading (Frisén method), high and low contrast visual acuity, and SD-OCT imaging at study entry, 3 and 6 months. Study eye (worse perimetric mean deviation, PMD) results were used for most analyses. Main Outcome Measures Retinal nerve fiber layer (RNFL), total retinal thickness (TRT), optic nerve volume (ONHV), and retinal ganglion cell layer (GCL) measurements were derived using 3-D segmentation. Results Study entry OCT values were similar in both treatment groups. At 6 months, the ACZ group had greater reduction than the placebo group for RNFL (175 μm vs 89 μm, p=0.001), TRT (220 μm vs 113 μm, p=0.001), and ONHV (4.9 mm3 vs 2.1 mm3, p=0.001). The RNFL (p=0.01), TRT (p=0.003), and ONHV (p=0.002) also showed less swelling in subjects who lost ≥ 6% of study entry weight. GCL thinning was minor in ACZ (3.6 μm) and placebo (2.1 μm, p =0.06) groups. The RNFL, TRT, and ONHV showed moderate correlations (r=0.48-0.59, p≤0.0001) with Frisén grade. The 14 eyes with GCL thickness <5th percentile of controls had worse PMD (p=0.001) than study eyes with GCL ≥ 5th percentile. Conclusions RNFL, TRT, and ONH volume measurements of swelling due to papilledema in IIH are effectively improved with ACZ and weight loss. In contrast to the strong correlation at baseline, OCT measures at 6

  18. Regulation of ion transport by pH and [HCO3-] in isolated gills of the crab Neohelice (Chasmagnathus) granulata.

    PubMed

    Tresguerres, Martin; Parks, Scott K; Sabatini, Sebastian E; Goss, Greg G; Luquet, Carlos M

    2008-03-01

    Posterior isolated gills of Neohelice (Chasmagnathus) granulatus were symmetrically perfused with hemolymph-like saline of varying [HCO3-] and pH. Elevating [HCO3-] in the saline from 2.5 to 12.5 mmol/l (pH 7.75 in both cases) induced a significant increase in the transepithelial potential difference (Vte), a measure of ion transport. The elevation in [HCO3-] also induced a switch from acid secretion (-43.7 +/- 22.5 microequiv.kg(-1).h(-1)) in controls to base secretion (84.7 +/- 14.4 microequiv.kg(-1).h(-1)). The HCO3(-)-induced Vte increase was inhibited by basolateral acetazolamide (200 micromol/l), amiloride (1 mmol/l), and ouabain (5 mmol/l) but not by bafilomycin (100 nmol/l). The Vte response to HCO3(-) did not take place in Cl(-)-free conditions; however, it was unaffected by apical SITS (2 mmol/l) or DIDS (1 mmol/l). A decrease in pH from 7.75 to 7.45 pH units in the perfusate also induced a significant increase in Vte, which was matched by a net increase in acid secretion of 67.8 +/- 18.4 microequiv kg(-1) h(-1). This stimulation was sensitive to basolateral acetazolamide, bafilomycin, DIDS, and Na+-free conditions, but it still took place in Cl(-)-free saline. Therefore, the cellular response to low pH is different from the HCO3(-)-stimulated response. We also report V-H+-ATPase- and Na+-K+-ATPase-like immunoreactivity in gill sections for the first time in this crab. Our results suggest that carbonic anhydrase (CA), basolateral Na+/H+ exchangers and Na+-K+-ATPase and apical anion exchangers participate in the HCO3(-)-stimulated response, while CA, apical V-H+-ATPase and basolateral HCO3(-)-dependent cotransporters mediate the response to low pH.

  19. Regulation of the sodium bicarbonate cotransporter kNBC1 function: role of Asp(986), Asp(988) and kNBC1-carbonic anhydrase II binding.

    PubMed

    Gross, Eitan; Pushkin, Alexander; Abuladze, Natalia; Fedotoff, Olga; Kurtz, Ira

    2002-11-01

    The HCO(3)(-) : Na(+) cotransport stoichiometry of the electrogenic sodium bicarbonate cotransporter kNBC1 determines the reversal potential (E(rev)) and thus the net direction of transport of these ions through the cotransporter. Previously, we showed that phosphorylation of kNBC1-Ser(982) in the carboxy-terminus of kNBC1 (kNBC1-Ct), by cAMP-protein kinase A (PKA), shifts the stoichiometry from 3 : 1 to 2 : 1 and that binding of bicarbonate to the cotransporter is electrostaticaly modulated. These results raise the possibility that phosphorylated kNBC1-Ser(982), or other nearby negatively charged residues shift the stoichiometry by blocking a bicarbonate-binding site. In the current study, we examined the role of the negative charge on Ser(982)-phosphate and three aspartate residues in a D986NDD custer in altering the stoichiometry of kNBC1. mPCT cells expressing kNBC1 mutants were grown on filters and mounted in an Ussing chamber for electrophysiological studies. Enhanced green fluorescence protein (EGFP)-tagged mutant constructs expressed in the same cells were used to determine the phosphorylation status of kNBC1-Ser(982). The data indicate that both kNBC1-Asp(986) and kNBC1-Asp(988), but not kNBC1-Asp(989), are required for the phosphorylation-induced shift in stoichiometry. A homologous motif (D887ADD) in the carboxy-terminus of the anion exchanger AE1 binds to carbonic anhydrase II (CAII). In isothermal titration calorimetry experiments, CAII was found to bind to kNBC1-Ct with a K(D) of 160 +/- 10 nM. Acetazolamide inhibited the short-circuit current through the cotransporter by 65 % when the latter operated in the 3 : 1 mode, but had no effect on the current in the 2 : 1 mode. Acetazolamide did not affect the cotransport stoichiometry or the ability of 8-Br-cAMP to shift the stoichiometry. Although CAII does not affect the transport stoichiometry, it may play an important role in enhancing the flux through the transporter when kNBC1-Ser(982) is

  20. Water-soluble drug partitioning and adsorption in HEMA/MAA hydrogels.

    PubMed

    Dursch, Thomas J; Taylor, Nicole O; Liu, David E; Wu, Rong Y; Prausnitz, John M; Radke, Clayton J

    2014-01-01

    Two-photon confocal microscopy and back extraction with UV/Vis-absorption spectrophotometry quantify equilibrium partition coefficients, k, for six prototypical drugs in five soft-contact-lens-material hydrogels over a range of water contents from 40 to 92%. Partition coefficients were obtained for acetazolamide, caffeine, hydrocortisone, Oregon Green 488, sodium fluorescein, and theophylline in 2-hydroxyethyl methacrylate/methacrylic acid (HEMA/MAA, pKa≈5.2) copolymer hydrogels as functions of composition, aqueous pH (2 and 7.4), and salinity. At pH 2, the hydrogels are nonionic, whereas at pH 7.4, hydrogels are anionic due to MAA ionization. Solute adsorption on and nonspecific electrostatic interaction with the polymer matrix are pronounced. To express deviation from ideal partitioning, we define an enhancement or exclusion factor, E ≡ k/φ1, where φ1 is hydrogel water volume fraction. All solutes exhibit E > 1 in 100 wt % HEMA hydrogels owing to strong specific adsorption to HEMA strands. For all solutes, E significantly decreases upon incorporation of anionic MAA into the hydrogel due to lack of adsorption onto charged MAA moieties. For dianionic sodium fluorescein and Oregon Green 488, and partially ionized monoanionic acetazolamide at pH 7.4, however, the decrease in E is more severe than that for similar-sized nonionic solutes. Conversely, at pH 2, E generally increases with addition of the nonionic MAA copolymer due to strong preferential adsorption to the uncharged carboxylic-acid group of MAA. For all cases, we quantitatively predict enhancement factors for the six drugs using only independently obtained parameters. In dilute solution for solute i, Ei is conveniently expressed as a product of individual enhancement factors for size exclusion (Ei(ex)), electrostatic interaction (Ei(el)), and specific adsorption (Ei(ad)):Ei≡Ei(ex)Ei(el)Ei(ad). To obtain the individual enhancement factors, we employ an extended Ogston mesh-size distribution for Ei

  1. Retinitis Pigmentosa and Other Dystrophies.

    PubMed

    Mrejen, Sarah; Audo, Isabelle; Bonnel, Sébastien; Sahel, José-Alain

    2017-01-01

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal degenerations characterized by progressive degeneration of rod and cone cells that affects predominantly peripheral visual fields. Macular edema may cause additional central visual acuity decrease. Cystoid macular edema (CME) is one of the few treatable causes of visual loss in RP. The prevalence of CME in RP has been found to be between 10 and 20% on fluorescein angiography-based studies, and as high as 49% on reports based on optical coherence tomography. Macular edema can manifest at any stage of the disease and may be unilateral or bilateral. It can be found in any genetic form, but is more often associated with RP caused by CRB1 mutations. The origin of macular edema in RP patients still remains poorly understood. Some mechanisms have been suggested, including antiretinal antibodies (retinal, carbonic anhydrase, and enolase antibodies), vitreous traction, retinal pigment epithelium dysfunction, and Müller cell edema. There is no gold standard therapeutic strategy. Drug therapy is the primary treatment. Systemic carbonic anhydrase inhibitors, such as oral acetazolamide or topical dorzolamide, are still the mainstays of initial therapy. If CME is refractory to acetazolamide, intravitreal corticosteroid injections may be a therapeutic option. However, antivascular endothelium growth factor injections have limited effect and should be avoided. Vitrectomy has also been evaluated, but its exact role remains to be determined. The benefits of these therapies are variable among patients. The establishment of therapeutic approaches is limited by our poor understanding of the pathophysiology of CME in patients with RP. Autoimmune retinopathies (AIRs) are a group of rare diseases characterized by acute or subacute progressive vision loss and are thought to be mediated by autoantibodies specific to retinal antigens. The AIRs encompass paraneoplastic syndromes, such as cancer-associated retinopathy and

  2. Cerenkov specific contrast agents for detection of pH in vivo

    PubMed Central

    Czupryna, Julie; Kachur, Alexander V.; Blankemeyer, Eric; Popov, Anatoliy V.; Karp, Joel S.; Delikatny, E. James

    2015-01-01

    We report the design, testing and in vivo application of pH sensitive contrast agents designed specifically for Cerenkov imaging. Radioisotopes used for positron emission tomography (PET) emit photons via Cerenkov radiation. The multispectral emission of Cerenkov radiation allows for selective bandwidth quenching, where a band of photons are quenched by absorption by a functional dye. Under acidic conditions, 18F-labeled derivatives emit the full spectrum of Cerenkov light. Under basic conditions, the dyes change color and a wavelength-dependent quenching of Cerenkov emission is observed. METHODS Mono and di-18F-labeled derivatives of phenolsulfonphthalein (phenol red) and meta-cresolsulfonphthalein (cresol purple) were synthesized by electrophilic fluorination. Cerenkov emission was measured at different wavelengths as a function of pH in vitro. Intramolecular response was measured in fluorinated probes; intermolecular quenching by mixing phenolphthalein with 18F FDG. Monofluorocresol purple (MFCP) was tested in mice treated with acetazolamide to cause urinary alkalinization and Cerenkov images compared to PET images. RESULTS Fluorinated pH indicators were produced with radiochemical yields of 4-11% at >90% purity. Selective Cerenkov quenching was observed intramolecularly with difluorophenol red or MFCP, and intermolecularly in phenolphthalein 18F-FDG mixtures. The probes were selectively quenched in the bandwidth closest to the indicator’s absorption maximum (λmax) at pHs above the indicator pKa. Addition of acid or base to the probes resulted in reversible switching from unquenched to quenched emission. In vivo, the bladders of acetazolamide-treated mice exhibited a wavelength-dependent quenching in Cerenkov emission, with the greatest reduction occurring near the λmax. Ratiometric imaging at two wavelengths showed significant decreases in Cerenkov emission at basic pH and allowed the estimation of absolute pH in vivo. CONCLUSIONS We have created contrast

  3. The effect of carbon dioxide on the intracellular pH and buffering power of snail neurones.

    PubMed Central

    Thomas, R C

    1976-01-01

    1. Intracellular pH (pHi) was measured using pH-sensitive glass micro-electrodes. The effects on pHi of CO2 applied externally and HCO3-, H+ and NH4+ injected iontophoretically, were investigated. 2. The transport numbers for iontophoretic injection into aqueous micro-droples were found by potentiometric titration to be 0-3 for HCO3- and 0-94 for H+. 3. Exposure to Ringer, pH 7-5, equilibrated with 2-2% CO2 caused a rapid, but only transient, fall in pHi. Within 1 or 2 min pHi began to return exponentially to normal, with a time constant of about 5 min. 4. When external CO2 was removed, pHi rapidly increased, and then slowly returned to normal. The pHi changes with CO2 application or removal gave a calculated intracellular buffer value of about 30 m-equiv H+/pH unit per litre. 5. Injection of HCO3- caused a rise in pHi very similar to that seen on removal of external CO2. 6. The pHi responses to CO2 application, CO2 removal and HCO3- injection were slowed by the carbonic anhydrase inhibitor acetazolamide. 7. H+ injection caused a transient fall in pHi. In CO2 Ringer pHi fell less and recovered faster than in CO2-free Ringer. Calculation of the internal buffer value from the pHi responses to H+ and HCO3- injection gave very similar values. 8. The internal buffer value (measured by H+ injection) was greatly increased by exposure to CO2 Ringer. Acetazolamide reduced this effect of CO2, suggesting that the function of intracellular carbonic anhydrase may be to maximize the internal buffering power in CO2. 9. It was concluded that the internal HCO3- was determined primarily by the CO2 level and pHi, that internal HCO3- made a large contribution to the buffering power, and that after internal acidfication pHi was restored to normal by active transport of H+, OH- or HCO3- across the cell membrane. The active transport was much faster in CO2 than in CO2-free Ringer. PMID:4614

  4. Antikaliuretic action of trimethoprim is minimized by raising urine pH.

    PubMed

    Schreiber, M; Schlanger, L E; Chen, C B; Lessan-Pezeshki, M; Halperin, M L; Patnaik, A; Ling, B N; Kleyman, T R

    1996-01-01

    This study was designed to test the hypothesis that the antikaliuresis caused by trimethoprim could be diminished by alkalinizing the luminal fluid in the CCD, thereby converting trimethoprim from its cationic, active form to an electroneutral, inactive, form. Trimethoprim-induced inhibition of transepithelial Na+ transport was examined in A6 distal nephron cells by analysis of short circuit current. The voltage-dependence of the trimethoprim-induced block of Na+ channels was examined with patch clamp recordings of A6 cells. The antikaliuretic effect of trimethoprim was examined in vivo in rats pretreated with deoxycorticosterone and with NH4Cl to lower urine pH, and in rats also receiving acetazolamide to raise urine pH. We found that the concentration of trimethoprim required to inhibit the amiloride sensitive component of short circuit current by 50% (IC50) was 340 microM (at pH 8.2) and 50 microM (at pH 6.3). The IC50S of protonated trimethoprim were similar (34 microM at pH 8.2 and 45 microM at pH 6.3). The mean time open for the high selectivity, Na+ channel was reduced from 1679 +/- 387 msec to 502 +/- 98 msec with addition of 10-5 M trimethoprim to patch pipette solution at the resting membrane potential (-Vpipette = 0 mV). further decreases in mean time open were observed as -Vpipette was reduced (that is, apical membrane hyperpolarization) to -40 mV (mean time open = 217 +/- 85 msec) and to -80 mV (mean time open = 69 +/- 13 msec). In vivo, trimethoprim caused a > 50% reduction in potassium (K+) excretion due primarily to a fall in the [K+] in the lumen of the terminal CCD. This effect of trimethoprim was markedly attenuated in an alkaline urine induced by acetazolamide. We conclude that it is the charged, protonated species of trimethoprim which blocks epithelial Na+ channels. Increasing urinary pH decreases the concentration of the charged species of trimethoprim and minimizes its antikaliuretic effect.

  5. Discovery and microassay of a nitrite-dependent carbonic anhydrase activity by stable-isotope dilution gas chromatography-mass spectrometry.

    PubMed

    Zinke, Maximilian; Hanff, Erik; Böhmer, Anke; Supuran, Claudiu T; Tsikas, Dimitrios

    2016-01-01

    The intrinsic activity of carbonic anhydrase (CA) is the hydration of CO2 to carbonic acid and its dehydration to CO2. CA may also function as esterase and phosphatase. Recently, we demonstrated that renal CA is mainly responsible for the reabsorption of nitrite (NO2(-)) which is the most abundant reservoir of the biologically highly potent nitric oxide (NO). By means of a stable-isotope dilution GC-MS method, we discovered a novel CA activity which strictly depends upon nitrite. We found that bovine erythrocytic CAII (beCAII) catalyses the incorporation of (18)O from H2 (18)O into nitrite at pH 7.4. After derivatization with pentafluorobenzyl bromide, gas chromatographic separation and mass spectrometric analysis, we detected ions at m/z 48 for singly (18)O-labelled nitrite ((16)O=N-(18)O(-)/(18)O=N-(16)O(-)) and at m/z 50 for doubly (18)O-labelled nitrite ((18)O=N-(18)O(-)) in addition to m/z 46 for unlabelled nitrite. Using (15)N-labelled nitrite ((15)NO2 (-), m/z 47) as an internal standard and selected-ion monitoring of m/z 46, m/z 48, m/z 50 and m/z 47, we developed a GC-MS microassay for the quantitative determination of the nitrite-dependent beCAII activity. The CA inhibitors acetazolamide and FC5 207A did not alter beCAII-catalysed formation of singly and doubly (18)O-labelled nitrite. Cysteine and the experimental CA inhibitor DIDS (a diisothiocyanate) increased several fold the beCAII-catalysed formation of the (18)O-labelled nitrite species. Cysteine, acetazolamide, FC5 207A, and DIDS by themselves had no effect on the incorporation of (18)O from H2 (18)O into nitrite. We conclude that erythrocytic CA possesses a nitrite-dependent activity which can only be detected when nitrite is used as the substrate and the reaction is performed in buffers of neutral pH values prepared in H2 (18)O. This novel CA activity, i.e., the nitrous acid anhydrase activity, represents a bioactivation of nitrite and may have both beneficial (via S-nitrosylation and subsequent

  6. Serosal bicarbonate protects against acid injury to rabbit esophagus.

    PubMed

    Tobey, N A; Powell, D W; Schreiner, V J; Orlando, R C

    1989-06-01

    The role of serosal bicarbonate ions (HCO3-) in protection against acid injury was investigated in rabbit esophageal mucosa mounted in Ussing chambers. Luminal acidification reduced potential difference and resistance in tissues exposed serosally to HCO3- or (unbuffered) HCO3-free solution. Whereas resistance declined similarly in both groups, potential difference declined less in HCO3- solution. After washout, HCO3-bathed tissues also had a greater increase in resistance, lower permeability to mannitol, and less histologic damage. Furthermore, as protection by HCO3- was not blocked by pretreatment with either the anion exchange blocker, 4 acetamido-4'-isothiocyanatostilbene 2-2'-disulfonic acid, or the carbonic anhydrase inhibitor, acetazolamide, and replacement of HCO3- with N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid, a buffer impermeant to cells, was protective, an extracellular site for protection by HCO3- was likely. Where in the extracellular space HCO3- buffers H+ is unclear, but the absence of change in luminal pH and the inability to prevent the acid-induced increase in permeability in HCO3-bathed tissues argue against a luminal (preepithelial) site. Also, rapid repair was not demonstrated, indicating that a luminal site for protection after surface cell damage was unlikely. We conclude that serosal HCO3- is important in esophageal protection against acid damage by buffering H+ within the intercellular compartment of the extracellular space.

  7. High Altitude Medical Problems

    PubMed Central

    Hultgren, Herbert N.

    1979-01-01

    Increased travel to high altitude areas by mountaineers and nonclimbing tourists has emphasized the clinical problems associated with rapid ascent. Acute mountain sickness affects most sojourners at elevations above 10,000 feet. Symptoms are usually worse on the second or third day after arrival. Gradual ascent, spending one to three days at an intermediate altitude, and the use of acetazolamide (Diamox) will prevent or ameliorate symptoms in most instances. Serious and potentially fatal problems, such as high altitude pulmonary edema or cerebral edema, occur in approximately 0.5 percent to 1.0 percent of visitors to elevations above 10,000 feet—especially with heavy physical exertion on arrival, such as climbing or skiing. Early recognition, high flow oxygen therapy and prompt descent are crucially important in management. Our knowledge of the causes of these and other high altitude problems, such as retinal hemorrhage, systemic edema and pulmonary hypertension, is still incomplete. Even less is known of the effect of high altitudes on medical conditions common at sea level or on the action of commonly used drugs. ImagesFigure 2. PMID:483805

  8. Common High Altitudes Illnesses a Primer for Healthcare Provider

    PubMed Central

    Mohsenin, Vahid

    2015-01-01

    Exposure to high altitude imposes significant strain on cardiopulmonary system and the brain. As a consequence, sojourners to high altitude frequently experience sleep disturbances, often reporting restless and sleepless nights. At altitudes above 3,000 meters (9,800 ft) almost all healthy subjects develop periodic breathing especially during NREM sleep. Sleep architecture gradually improves with increased NREM and REM sleep despite persistence of periodic breathing. The primary reason for periodic breathing at high altitude is a hypoxic-induced increase in chemoreceptor sensitivity to changes in PaCO2 – both above and below eupnea, leading to periods of apnea and hyperpnea. Acetazolamide improves sleep by reducing the periodic breathing through development of metabolic acidosis and induced hyperventilation decreasing the plant gain and widening the PCO2 reserve. This widening of the PCO2 reserve impedes development of central apneas during sleep. Benzodiazepines and GABA receptor antagonist such as zolpidem improve sleep without affecting breathing pattern or cognitive functions. PMID:27057512

  9. Synthesis and in vivo diuretic activity of some new benzothiazole sulfonamides containing quinoxaline ring system.

    PubMed

    Husain, Asif; Madhesia, Diwakar; Rashid, Mohd; Ahmad, Aftab; Khan, Shah Alam

    2016-12-01

    A series of new 6-substituted-N-[3-{2-(substituted phenyl)-ethenyl} quinoxaline-2(1H)-ylidene]-1,3-benzothiazole-2-amine (4a-f) were designed and synthesized by condensing 2-amino-benzothiazole-6-sulfonic acid amide (1) with chalcones of quinoxaline-2-one (3a-f) in a hope to obtain promising and a new class of diuretic agents. Structures of all the newly synthesized compounds were characterized by spectral data and elemental analysis. The pharmacological studies in experimental rats indicates that compound 4c possesses excellent in vivo diuretic activity of 1.13 and appears to be a better diuretic agent than the reference drugs, acetazolamide (1.0) and urea (0.88). Insight of the binding mode of the synthesized compounds (ligand) into the binding sites of carbonic anhydrase enzyme (PDF code: 4KUV) was provided by docking studies, performed with the help of Maestro 9.0 docking software. Further pharmacokinetic and toxicological studies are needed to confirm the safety of compound 4c which emerged as a lead diuretic compound.

  10. Encephaloduroarteriosynangiosis for cerebral proliferative angiopathy with cerebral ischemia.

    PubMed

    Kono, Kenichi; Terada, Tomoaki

    2014-12-01

    Cerebral proliferative angiopathy (CPA) is a rare clinical entity. This disorder is characterized by diffuse vascular abnormalities with intermingled normal brain parenchyma, and is differentiated from classic arteriovenous malformations. The management of CPA in patients presenting with nonhemorrhagic neurological deficits due to cerebral ischemia is challenging and controversial. The authors report a case of adult CPA with cerebral ischemia in which neurological deficits were improved after encephaloduroarteriosynangiosis (EDAS). A 28-year-old man presented with epilepsy. Magnetic resonance imaging and angiography showed a diffuse vascular network (CPA) in the right hemisphere. Antiepileptic medications were administered. Four years after the initial onset of epilepsy, the patient's left-hand grip strength gradually decreased over the course of 1 year. The MRI studies showed no infarcts, but technetium-99m-labeled ethyl cysteinate dimer ((99m)Tc-ECD) SPECT studies obtained with acetazolamide challenge demonstrated hypoperfusion and severely impaired cerebrovascular reactivity over the affected hemisphere. This suggested that the patient's neurological deficits were associated with cerebral ischemia. The authors performed EDAS for cerebral ischemia, and the patient's hand grip strength gradually improved after the operation. Follow-up angiography studies obtained 7 months after the operation showed profound neovascularization through the superficial temporal artery and the middle meningeal artery. A SPECT study showed slight improvement of hypoperfusion at the focal region around the right motor area, indicating clinical improvement from the operation. The authors conclude that EDAS may be a treatment option for CPA-related hypoperfusion.

  11. Modified encephaloduroarteriosynangiosis with bifrontal encephalogaleoperiosteal synangiosis for the treatment of pediatric moyamoya disease. Technical note.

    PubMed

    Park, Jae Hyo; Yang, Seung-Yeob; Chung, You-Nam; Kim, Jeong Eun; Kim, Seung-Ki; Han, Dae Hee; Cho, Byung-Kyu

    2007-03-01

    The authors describe a modified technique of encephaloduroarteriosynangiosis (EDAS) with bifrontal encephalogaleoperiosteal synangiosis (EGPS) and present the preliminary results of the procedure. Between January 2004 and June 2005 the authors performed modified EDAS with bifrontal EGPS in 17 patients with moyamoya disease. Surgical results were evaluated in terms of clinical outcomes, changes visible on neuroimages, extent of revascularization noted on angiograms, and hemodynamic changes demonstrated on single-photon emission computed tomography (SPECT) scans. The follow-up period ranged from 6 to 21 months (mean 11.5 months). The overall clinical outcomes were excellent or good in 15 patients (88.2%) and poor in two (11.8%). The overall morbidity rate was 5.9% (one of 17 patients). Based on changes in the anterior cerebral artery (ACA) and middle cerebral artery (MCA) territories after surgery, as shown on SPECT scans following administration of acetazolamide, 14 patients (82.4%) exhibited an improved vascular reserve capacity in both the ACA and MCA territories. It is the authors' opinion that wide covering of the cortex is necessary for sufficient revascularization. In the present study they demonstrate that modified EDAS with bifrontal EGPS is a safe and efficient surgical approach that covers not only the MCA territory but also the ACA territory.

  12. Carbonic anhydrase inhibitors with dual-tail moieties to match the hydrophobic and hydrophilic halves of the carbonic anhydrase active site.

    PubMed

    Tanpure, Rajendra P; Ren, Bin; Peat, Thomas S; Bornaghi, Laurent F; Vullo, Daniela; Supuran, Claudiu T; Poulsen, Sally-Ann

    2015-02-12

    We present a new approach to carbonic anhydrase II (CA II) inhibitor design that enables close interrogation of the regions of the CA active site where there is the greatest variability in amino acid residues among the different CA isozymes. By appending dual tail groups onto the par excellence CA inhibitor acetazolamide, compounds that may interact with the distinct hydrophobic and hydrophilic halves of the CA II active site were prepared. The dual-tail combinations selected included (i) two hydrophobic moieties, (ii) two hydrophilic moieties, and (iii) one hydrophobic and one hydrophilic moiety. The CA enzyme inhibition profile as well as the protein X-ray crystal structure of compound 3, comprising one hydrophobic and one hydrophilic tail moiety, in complex with CA II is described. This novel dual-tail approach has provided an enhanced opportunity to more fully exploit interactions with the CA active site by enabling these molecules to interact with the distinct halves of the active site. In addition to the dual-tail compounds, a corresponding set of single-tail derivatives was synthesized, enabling a comparative analysis of the single-tail versus dual-tail compound CA inhibition profile.

  13. Inhibition of aminophylline-induced convulsions in mice by antiepileptic drugs and other agents.

    PubMed

    Czuczwar, S J; Janusz, W; Wamil, A; Kleinrok, Z

    1987-12-15

    Common antiepileptic drugs and agents affecting different neurotransmitter systems were studied against aminophylline (280 mg/kg i.p.)-induced convulsions in mice. All drugs and agents were administered i.p. Diazepam and phenobarbital antagonized the whole seizure pattern and the respective ED50 values for the clonic phase were 3.5 and 62 mg/kg. Valproate at 500 mg/kg protected fewer than 50% of mice against the clonic phase. The remaining antiepileptics (acetazolamide, up to 1,000 mg/kg; carbamazepine and diphenylhydantoin, up to 50 mg/kg; ethosuximide, 500 mg/kg and trimethadione, 400 mg/kg) were totally ineffective in this respect. Propranolol (up to 20 mg/kg), baclofen (20 mg/kg), gamma-hydroxybutyric acid (300 mg/kg), aminooxyacetic acid (20 mg/kg), clonidine (up to 0.2 mg/kg), ketamine (30 mg/kg), atropine (20 mg/kg), papaverine (50 mg/kg) and L-phenylisopropyladenosine (2 mg/kg) did not affect the clonic phase either. Only antagonists of N-methyl-D-aspartic acid excitation, 2-amino-5-phosphonopentanoic acid and 2-amino-7-phosphonoheptanoic acid afforded protection against aminophylline-induced clonic seizure activity. The results show that aminophylline convulsions are relatively resistant to antiepileptic drugs and suggest that antagonists of excitatory transmission are potential antiaminophylline drugs.

  14. Interaction of 13 CO 2 and bicarbonate with human hemoglobin preparations.

    PubMed

    Morrow, J S; Keim, P; Visscher, R B; Marshall, R C; Gurd, F R

    1973-05-01

    Formation of (13)C-resonances attributable to carbamino derivatives has been observed in human erythrocyte hemolysate preparations equilibrated with (13)CO(2) at 33 degrees . Carbamino formation is most marked in deoxyhemoglobin and at alkaline pH, and is very largely inhibited by the addition of 2,3-diphosphoglycerate or conversion to oxyhemoglobin. The prominent carbamino resonance at 30.0 ppm upfield of CS(2) is visible in the spectrum of packed, deoxygenated erythrocytes equilibrated in (13)CO(2). This chemical shift falls close to that observed with sperm-whale myoglobin and within 2 ppm upfield of that seen with simple amino acids and peptides. The bicarbonate-carbonate resonance near 33 ppm is broad in the hemoglobin preparations, which always contain some carbonic anhydrase, but becomes narrow in the presence of the carbonic anhydrase inhibitor, acetazolamide. The nuclear magnetic resonance condition of intermediate exchange rate with dissolved CO(2) (68.4 ppm) obtains in the absence of inhibitor. The process has marked consequences in reducing the spin-lattice relaxation time, T(1), of the bicarbonate resonance by more than 10 times. The deoxyhemoglobin carbamino resonance has a T(1) value of 700 msec, indistinguishable from that of the protein carbonyl resonance envelope.

  15. High Altitude Illnesses in Hawai‘i

    PubMed Central

    2014-01-01

    High Altitude Headache (HAH), Acute Mountain Sickness (AMS), and High Altitude Cerebral Edema (HACE) are all high altitude related illnesses in order of severity from the mildly symptomatic to the potentially life-threatening. High altitude illnesses occur when travelers ascend to high altitudes too rapidly, which does not allow enough time for the body to adjust. Slow graded ascent to the desired altitude and termination of ascent if AMS symptoms present are keys to illness prevention. Early recognition and rapid intervention of AMS can halt progression to HACE. Pharmacologic prophylaxis with acetazolamide is a proven method of prevention and treatment of high altitude illness. If prevention fails then treatment modalities include supplemental oxygen, supportive therapy, hyperbaric treatment, and dexamethasone. Given the multitude of visitors to the mountains of Hawai‘i, high altitude illness will continue to persist as a prevalent local condition. This paper will emphasize the prevention and early diagnosis of AMS so that the illness does not progress to HACE. PMID:25478293

  16. Intrapulmonary receptors in the Tegu lizard: II. Functional characteristics and localization;.

    PubMed

    Scheid, P; Kuhlmann, W D; Fedde, M R

    1977-02-01

    Intrapulmonary receptors identified in the Tegu lizard by single-unit vagal recording (Fedde et al., 1977) were subjected to a number of stimuli and localized within the lung. Some carbon dioxide receptors could follow periodic changes in intrapulmonary CO2 concentrations as rapidly as 1.3 Hz; No oxygen sensitivity was observed with this receptor type, and halothane markedly depressed the discharge frequency. In response to intravenously injected acetazolamide they increased their discharge frequency and became almost totally insensitive to CO2, suggesting molecular per se is not the direct controller of receptor discharge; These receptors show many of the functional characteristics described for those in the avian lung. Afferent activity from both CO2 and mechanoreceptors could be elicited by electrically stimulating the lung surface. The CO2 receptors appeared to be organized in a receptive field covering more than 1 cm2 of lung surface, multiple receptors being innervated by a single afferent fiber. Activity in afferent fibers from mechanoreceptors could be evoked from only one distinct spot on the lung surface. Conduction velocities of afferent fibers from CO2 receptors ranged from 1 to 3 m-sec-1; from mechanoreceptors, from 1.9 to 5.2 m-sec-1.

  17. Modulation of carbonic anhydrase activity in two nitrogen fixing cyanobacteria, Nostoc calcicola and Anabaena sp.

    PubMed

    Jaiswal, Pranita; Prasanna, Radha; Kashyap, Ajai Kumar

    2005-10-01

    The activity of enzyme carbonic anhydrase (CA) was investigated in two diazotrophic cyanobacteria, Anabaena sp. (ARM 629) and Nostoc calcicola, in the presence of CO2/NaHCO3 and different inhibitors. The CA activity increased when the cells were pretreated with a high concentration of CO2/NaHCO3 and then transferred to ambient level CO2. Maximum activity of CA was observed after 8 h of incubation in light on transfer of cells from high Ci to ambient level CO2, and was low when incubated in dark. Addition of the photosynthetic inhibitor DCMU brought about a differential reduction in CA activity, depending on the carbon source (NaHCO3/CO2). CA inhibitors--ethoxyzolamide (EZ) and acetazolamide (AZ)--inhibited the enzyme activity in both the genera, but the extent of inhibition was greater in Anabaena sp. than in N. calcicola. Such a variation in extent of inhibition/stimulation of CA activity being different in the two genera reflects differences in their inherent potential and genetic background. The relevance of such cyanobacterial strains as CO2 sinks is also discussed.

  18. Late onset hydrocephalus in children with tuberculous meningitis

    PubMed Central

    Sharma, Disha; Shah, Ira; Patel, Sharad

    2016-01-01

    Hydrocephalus is a known complication of tuberculous meningitis (TBM). It is almost always present in patients who have had the disease for four to six weeks. However, hydrocephalus can also develop later in the disease course as seen in our 3 patients. All 3 patients had multi-drug resistant (MDR) tuberculosis (TB) and developed hydrocephalus after variable time after starting second line anti-tuberculous therapy (ATT). A 7 years old girl had hydrocephalus at onset of TBM and was shunted but the hydrocephalus increased in size after 6 months of being on second line ATT in spite of a patent ventricular peritoneal (VP) shunt. Hydrocephalus responded to oral acetazolamide. Other 2 patients, a 2 years old girl and 3½ years old boy developed hydrocephalus after being on treatment for 14 months. Both required insertion of VP shunt. Thus, in patients with MDR-TB, hydrocephalus may develop as late onset phenomenon and a neurological examination would be essential in each visit to the hospital.

  19. Characteristics of hydrogen ion transport in urinary bladder of water turtle.

    PubMed

    Steinmetz, P R

    1967-10-01

    The mechanism of acidification by the urinary bladder of the water turtle was studied in an in vitro system which permitted control and measurement of electrical and concentration driving forces. The rate of hydrogen ion secretion was measured by means of a pH stat technique in the absence of exogenous carbon dioxide and bicarbonate. Transport of hydrogen ion into the solution bathing the mucosal surface of the bladder was associated with the appearance of alkali in the serosal compartment. The mean rate of hydrogen ion secretion in the absence of electrical and concentration gradients across the bladder was 0.96 mumole/hr. The secretion rate was only slightly greater in the presence of the spontaneous potential difference. The maximal hydrogen ion gradient that could be generated by the bladder was 3.33 pH units in the presence of the spontaneous voltage and 3.02 pH units in the short-circuited state. Hydrogen ion secretion was markedly reduced by acetazolamide and anaerobiosis, which indicated that under our experimental conditions acidification depended on the production and enzymatic hydration of metabolic carbon dioxide. On the basis of the stoichiometry of the pH changes across the membrane under different conditions, it is suggested that the active transport mechanism for hydrogen ion is located near the mucosal surface of the epithelial cell and that the alkali generated in back of the pump moves passively into the serosal fluid along an electrochemical gradient.

  20. Idiopathic intracranial hypertension: ongoing clinical challenges and future prospects

    PubMed Central

    Julayanont, Parunyou; Karukote, Amputch; Ruthirago, Doungporn; Panikkath, Deepa; Panikkath, Ragesh

    2016-01-01

    Idiopathic intracranial hypertension (IIH) is an uncommon disorder characterized by increased intracranial pressure without radiological or laboratory evidence of intracranial pathology except empty sella turcica, optic nerve sheath with filled out cerebrospinal fluid spaces, and smooth-walled nonflow-related venous sinus stenosis or collapse. This condition typically affects obese women. The incidence of IIH is increasing with the rising prevalence of obesity. Persistent headache is the most common symptom. Visual impairment is a serious complication that may not be recognized by the patients. This paper reviews clinical manifestations, diagnostic challenges, and current treatments of IIH in adults. Various imaging modalities have been studied on their validity for detection of IIH and papilledema. This review also includes new studies on medical, surgical, and interventional management of this condition. Acetazolamide and topiramate are the only two medications that have been studied in randomized controlled trials about their efficacy in treatment of IIH. In patients who have severe visual impairment or progressive visual deterioration despite medical management, surgical or interventional treatment may be considered. The efficacy and complications of cerebrospinal fluid diversion, optic nerve sheath fenestration, and endovascular venous stenting reported in the last 3 decades have been summarized in this review. Finally, the prospective aspects of biomarkers and treatments are proposed for future research. PMID:26929666

  1. Extracellular carbonic anhydrase in the dogfish, Squalus acanthias: a role in CO2 excretion.

    PubMed

    Gilmour, K M; Perry, S F; Bernier, N J; Henry, R P; Wood, C M

    2001-01-01

    In Pacific spiny dogfish (Squalus acanthias), plasma CO(2) reactions have access to plasma carbonic anhydrase (CA) and gill membrane-associated CA. The objectives of this study were to characterise the gill membrane-bound CA and investigate whether extracellular CA contributes significantly to CO(2) excretion in dogfish. A subcellular fraction containing membrane-associated CA activity was isolated from dogfish gills and incubated with phosphatidylinositol-specific phospholipase C. This treatment caused significant release of CA activity from its membrane association, a result consistent with identification of the dogfish gill membrane-bound CA as a type IV isozyme. Inhibition constants (K(i)) against acetazolamide and benzolamide were 4.2 and 3.5 nmol L(-1), respectively. Use of a low dose (1.3 mg kg(-1) or 13 micromol L(-1)) of benzolamide to selectively inhibit extracellular CA in vivo caused a significant 30%-60% reduction in the arterial-venous total CO(2) concentration difference, a significant increase in Pco(2) and an acidosis, without affecting blood flow or ventilation. No effect of benzolamide on any measure of CO(2) excretion was detected in rainbow trout (Oncorhynchus mykiss). These results indicate that extracellular CA contributes substantially to CO(2) excretion in the dogfish, an elasmobranch, and confirm that CA is not available to plasma CO(2) reactions in rainbow trout, a teleost.

  2. Carbonic Anhydrase is Required for Statoconia Homeostasis in Organ Cultures of Statocysts from Aplysia californica

    NASA Technical Reports Server (NTRS)

    Pedrozo, H. A.; Schwartz, Z.; Nakaya, H.; Harrison, J. L.; Dean, D. D.; Wiederhold, M. L.; Boyan, B. D.

    1995-01-01

    A novel organ culture system has been developed to study the regulation of statoconia production in the gravity sensing organ in Aplysia californica. Statocysts were cultured in Leibovitz (LI5) medium supplemented with salts and Aplysia haemolymph for four days at 17 C. The viability of the system was evaluated by examining four parameters: statocyst morphology, the activity of the mechanosensory cilia in the statocyst, production of new statoconia during culture and change in statoconia volume after culture. There were no morphological differences in statocysts before and after culture when ciliary beating was maintained. There was a 29% increase in the number of statoconia after four days in culture. Mean statocyst, statolith and statoconia volumes were not affected by culture conditions. The presence of carbonic anhydrase in the statocysts was shown using immunohistochemistry. When statocysts were cultured in the presence of 4.0 x 10(exp -4) M acetazolamide to inhibit the enzyme activity, there was a decrease in statoconia production and statoconia volume, indicating a role for this enzyme in statoconia homeostasis, potentially, via pH regulation. These studies are the first to report a novel system for the culture of statocysts and show that carbonic anhydrase is involved in the regulation of statoconia volume and production.

  3. Therapeutic Options for Controlling Fluids in the Visual System

    NASA Technical Reports Server (NTRS)

    Curry, Kristina M.; Wotring, Virginia E.

    2014-01-01

    Visual Impairment/Intracranial Pressure (VIIP) is a newly recognized risk at NASA. The VIIP project examines the effect of long-term exposure to microgravity on vision of crewmembers before and after they return to Earth. Diamox (acetazolamide) is a medication which is used to decrease intraocular pressure; however, it carries a 3% risk of kidney stones. Astronauts are at a higher risk of kidney stones during spaceflight and the use Diamox would only increase the risk; therefore alternative therapies were investigated. Histamine 2 (H2) antagonist acid blockers such as cimetidine, ranitidine, famotidine and nizatidine are typically used to relieve the symptoms of gastroesophageal reflux disease (GERD). H2 receptors have been found in the human visual system, which has led to research on the use of H2 antagonist blockers to control fluid production in the human eye. Another potential therapeutic strategy is targeted at aquaporins, which are water channels that help maintain fluid homeostasis. Aquaporin antagonists are also known to affect intracranial pressure which can in turn alter intraocular pressure. Studies on aquaporin antagonists suggest high potential for effective treatment. The primary objective of this investigation is to review existing research on alternate medications or therapy to significantly reduce intracranial and intraocular pressure. A literature review was conducted. Even though we do not have all the answers quite yet, a considerable amount of information was discovered, and findings were narrowed, which should allow for more conclusive answers to be found in the near future.

  4. Inhibition of carbonic anhydrase II by steroidal and non-steroidal sulphamates.

    PubMed

    Ho, Y T; Purohit, A; Vicker, N; Newman, S P; Robinson, J J; Leese, M P; Ganeshapillai, D; Woo, L W L; Potter, B V L; Reed, M J

    2003-06-13

    Carbonic anhydrases (CAs) are expressed by many solid tumours where they may act to confer a growth advantage on malignant tissues. In this study we have examined the ability of a series of steroidal and non-steroidal sulphamates (originally developed as steroid sulphatase inhibitors) and related compounds to inhibit human CAII (hCAII) activity in vitro. Using a 96-well plate assay, oestrone-3-O-sulphamate (EMATE) and two coumarin-based sulphamate drugs (667 COUMATE and STX 118) were found to have IC(50) values of 25-59 nM for the inhibition of hCAII activity. These compounds therefore have a similar CAII inhibitory potency to that of acetazolamide (IC(50)=25 nM), a known hCAII inhibitor. Docking studies have been performed with selected compounds to the crystal structure of hCAII and excellent correlation of scores with biological activity was observed. This agrees with our recent observations when we were the first to report the inhibition of hCAII by STS inhibitors. These studies and initial results with docking to the crystal structure of the extracellular domain of hCAXII indicate that the STS sulphamate ester inhibitors should also be interesting candidates to pursue as inhibitors of CA isozymes that are over-expressed in human tumours.

  5. 14C Fixation by Leaves and Leaf Cell Protoplasts of the Submerged Aquatic Angiosperm Potamogeton lucens: Carbon Dioxide or Bicarbonate? 1

    PubMed Central

    Staal, Marten; Elzenga, J. Theo M.; Prins, Hidde B. A.

    1989-01-01

    Protoplasts were isolated from leaves of the aquatic angiosperm Potamogeton lucens L. The leaves utilize bicarbonate as a carbon source for photosynthesis, and show polarity; that is, acidification of the periplasmic space of the lower, and alkalinization of the space near the upper leaf side. At present there are two models under consideration for this photosynthetic bicarbonate utilization process: conversion of bicarbonate into free carbon dioxide as a result of acidification and, second, a bicarbonate-proton symport across the plasma membrane. Carbon fixation of protoplasts was studied at different pH values and compared with that in leaf strips. Using the isotopic disequilibrium technique, it was established that carbon dioxide and not bicarbonate was the form in which DIC actually crossed the plasma membrane. It is concluded that there is probably no true bicarbonate transport system at the plasma membrane of these cells and that bicarbonate utilization in this species apparently rests on the conversion of bicarbonate into carbon dioxide. Experiments with acetazolamide, an inhibitor of periplasmic carbonic anhydrase, and direct measurements of carbonic anhydrase activity in intact leaves indicate that in this species the role of this enzyme for periplasmic conversion of bicarbonate into carbon dioxide is insignificant. PMID:16666848

  6. Altitude Stress During Participation of Medical Congress.

    PubMed

    Kim, Soon Bae; Kim, Jong Sung; Kim, Sang Jun; Cho, Su Hee; Suh, Dae Chul

    2016-09-01

    Medical congresses often held in highlands. We reviewed several medical issues associated with altitude stress especially while physicians have participated medical congress held in high altitude. Altitude stress, also known as an acute mountain sickness (AMS), is caused by acute exposure to low oxygen level at high altitude which is defined as elevations at or above 1,200 m and AMS commonly occurs above 2,500 m. Altitude stress with various symptoms including insomnia can also be experienced in airplane. AMS and drunken state share many common features in symptoms, neurologic manifestations and even show multiple microbleeds in corpus callosum and white matter on MRI. Children are more susceptible to altitude stress than adults. Gradual ascent is the best method for the prevention of altitude stress. Adequate nutrition (mainly carbohydrates) and hydration are recommended. Consumption of alcohol can exacerbate the altitude-induced impairments in judgment and the visual senses and promote psychomotor dysfunction. For prevention or treatment of altitude stress, acetazolamide, phosphodiesterase inhibitors, dexamethasone and erythropoietin are helpful. Altitude stress can be experienced relatively often during participation of medical congress. It is necessary to remind the harmful effect of AMS because it can cause serious permanent organ damage even though the symptoms are negligible in most cases.

  7. Understanding idiopathic intracranial hypertension: mechanisms, management, and future directions.

    PubMed

    Markey, Keira A; Mollan, Susan P; Jensen, Rigmor H; Sinclair, Alexandra J

    2016-01-01

    Idiopathic intracranial hypertension is a disorder characterised by raised intracranial pressure that predominantly affects young, obese women. Pathogenesis has not been fully elucidated, but several causal factors have been proposed. Symptoms can include headaches, visual loss, pulsatile tinnitus, and back and neck pain, but the clinical presentation is highly variable. Although few studies have been done to support evidence-based management, several recent advances have the potential to enhance understanding of the causes of the disease and to guide treatment decisions. Investigators of the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT) reported beneficial effects of acetazolamide in patients with mild visual loss. Studies have also established weight loss as an effective disease-modifying treatment, and further clinical trials to investigate new treatments are underway. The incidence of idiopathic intracranial hypertension is expected to increase as rates of obesity increase; efforts to reduce diagnostic delays and identify new, effective approaches to treatment will be key to meeting the needs of a growing number of patients.

  8. Idiopathic intracranial hypertension in children: Diagnostic and management approach

    PubMed Central

    Hamad, Muddathir H; Alwadei, Ali H; Bashiri, Fahad A; Hassan, Hamdy H; Idris, Hiyam; Hassan, Saeed; Muayqil, Taim; Altweijri, Ikhlass; Salih, Mustafa A

    2016-01-01

    Idiopathic intracranial hypertension (IIH) is a rare neurological disorder in children. It is characterized by raised intracranial pressure (ICP) in the absence of brain parenchymal lesion, vascular malformations, hydrocephalus, or central nervous system (CNS) infection. The diagnosis is usually confirmed by high opening pressure of cerebrospinal fluid (CSF) with exclusion of secondary causes of intracranial hypertension. If not treated properly, it may lead to severe visual dysfunction. Here we review the etiology, clinical presentation, diagnostic criteria and management of IIH in children through illustration of the clinical and radiological presentation of a 13-year-old overweight girl who presented with severe headache, diplopia and bilateral papilledema. Otherwise, she had unremarkable neurological and systemic examinations. Lumbar puncture showed a high CSF opening pressure (360–540 mmH2O). Her investigations showed normal complete blood count (CBC), normal renal, liver, and thyroid function tests. Cerebrospinal fluid (CSF) and blood chemistry were unremarkable. Magnetic resonant image (MRI) of the brain demonstrated empty sella turcica, tortuous optic nerves, and flattening of the posterior sclera. Magnetic resonant venography (MRV) showed focal narrowing of the distal transverse sinuses and absence of venous sinus thrombosis. She required treatment with acetazolamide and prednisolone. With medical treatment, weight reduction, and exercise, our patient had a remarkable improvement in her symptoms with resolution of papilledema in two months. This review highlights the importance of early recognition and management of IIH to prevent permanent visual loss. PMID:28096561

  9. Trabeculectomy for traumatic hyphema with increased intraocular pressure.

    PubMed

    Graul, T A; Ruttum, M S; Lloyd, M A; Radius, R L; Hyndiuk, R A

    1994-02-15

    We reviewed the medical records of 11 consecutive patients who underwent trabeculectomy with anterior chamber washout and peripheral iridectomy as the primary surgical treatment for traumatic hyphema that was unresponsive to medical management. The mean intraocular pressure before surgery was 48 mm Hg. In ten of the patients the intraocular pressure was lowered to 21 mm Hg or lower after surgery and remained below that level up to the most recent follow-up visit, which ranged from eight to 97 months. One patient required a topical beta-blocker and oral acetazolamide to lower pressure to this level after surgery. Eight patients had visual acuity of 20/60 or better at last follow-up. Corneal blood staining occurred in eight patients. Compared with other techniques for surgical management of traumatic hyphema, trabeculectomy provides a means to keep intraocular pressure lowered while the remaining blood is clearing from the anterior chamber. Trabeculectomy with anterior chamber washout and peripheral iridectomy appears to be a safe and reliable procedure in the management of traumatic hyphemas in which medical management fails to control intraocular pressure.

  10. Cloning, expression and biochemical characterization of a β-carbonic anhydrase from the soil bacterium Enterobacter sp. B13.

    PubMed

    Eminoğlu, Ayşenur; Vullo, Daniela; Aşık, Aycan; Çolak, Dilşat Nigar; Supuran, Claudiu T; Çanakçı, Sabriye; Osman Beldüz, Ali

    2016-12-01

    A recombinant carbonic anhydrase (CA, EC 4.2.1.1) from the soil-dwelling bacterium Enterobacter sp. B13 was cloned and purified by Co(2+) affinity chromatography. Bioinformatic analysis showed that the new enzyme (denominated here B13-CA) belongs to the β-class CAs and to possess 95% homology with the ortholog enzyme from Escherichia coli encoded by the can gene, whereas its sequence homology with the other such enzyme from E. coli (encoded by the cynT gene) was of 33%. B13-CA was characterized kinetically as a catalyst for carbon dioxide hydration to bicarbonate and protons. The enzyme shows a significant catalytic activity, with the following kinetic parameters at 20 °C and pH of 8.3: kcat of 4.8 × 10(5) s(-1) and kcat/Km of 5.6 × 10(7) M(-1) × s(-1). This activity was potently inhibited by acetazolamide which showed a KI of 78.9 nM. Although only this compound was investigated for the moment as B13-CA inhibitor, further studies may reveal new classes of inhibitors/activators of this enzyme which may show biomedical or environmental applications, considering the posssible role of this enzyme in CaCO3 biomineralization processes.

  11. Evaluation of vanillic acid as inhibitor of carbonic anhydrase isozyme III by using a modified Hummel-Dreyer method: approach for drug discovery.

    PubMed

    Alzweiri, Muhammed; Al-Hiari, Yusuf

    2013-09-01

    α-3 carbonic anhydrase isozyme (CAIII) is the most abundant protein in adipocytes and considered insensitive to sulfonamide inhibitors. It was reported recently that the knock-down of CAIII is attributed with controlling lipogenesis. Thus inhibition of this target may lead to the discovery of new therapies against obesity and insulin resistance. Vanillic acid as a small molecule with coordinating groups and has a potential to bind zinc atoms in CA binding sites. Inhibition of CAIII by vanillic acid was evaluated by Hummel-Dreyer chromatography because it provides free interaction between ligand and macromolecule and introduces solution for faulty results obtained by current colorimetric assays. HPLC system of vanillic acid produces vacancy (negative) peak representing the amount of attached vanillic acid with CAIII. It was found that vanillic acid is able to bind with CAIII through two equilibria, one at equimolar ratio and another at 2:1 (vanillic acid-CAIII) ratio. The affinity constant of equimolar binding between CAIII and vanillic acid was found to be 14,400 m(-1) . It was found that vanillic acid binding with CAIII is much stronger than phenol and acetazolamide (positive controls).

  12. CARBONIC ANHYDRASE ACTIVITY OF INTEGRAL-FUNCTIONAL COMPLEXES OF THYLAKOID MEMBRANES OF SPINACH CHLOROPLASTS.

    PubMed

    Semenihin, A V; Zolotareva, O K

    2015-01-01

    Isolated thylakoid membranes were disrupted by treatment with nonionic detergents digitonin or dodecyl maltoside. Solubilized polypeptide complexes were separated by native gel charge shift electrophoresis. The position of ATP-synthase complex and its isolated catalytic part (CF1) within gel was determined using the color reaction for ATPase activity. Due to the presence of cytochromes, the red band in unstained gels corresponded to the cytochrome b6f complex. Localization of the cytochrome b6f complex, ATP synthase and coupling CF1 in the native gel was confirmed by their subunit composition determined after SDS-electrophoretic analysis. Carbonic anhydrase (CA) activity in polypeptide zones of PS II, cytochrome b6f complex, and ATP-synthase CF1 was identified in native gels using indicator bromothymol blue. CA activity of isolated CF1 in solution was determined by infrared gas analysis as the rate of bicarbonate dehydration. The water-soluble acetazolamide, an inhibitor of CA, unlike lipophilic ethoxyzolamide inhibited CA activity of CF1 Thus, it was shown for the first time that ATP-synthase has a component which is capable of catalyzing the interconversion of forms of carbonic acid associated with proton exchange. The data obtained suggest the presence of multiple forms of carbonic anhydrase in the thylakoid membranes of spinach chloroplasts and confirm their involvement in the proton transfer to the ATP synthase.

  13. Glucose Metabolism of the Isolated Eccrine Sweat Gland

    PubMed Central

    Sato, Kenzo; Dobson, Richard L.

    1973-01-01

    This paper attempts to further clarify the characteristics of Mecholyl- or epinephrine-stimulated glucose metabolism in the isolated monkey eccrine sweat gland with special emphasis on its relationship to increased sodium transport. The Mecholyl- or epinephrine-stimulated glucose metabolism (as estimated by either lactate or 14CO2 production or both) is seen only in the secretory coil and not in the duct. It is markedly suppressed in the absence of glucose, Na+, or K+. It is inhibited by ouabain (10−3 M) and partially suppressed in a low-sodium (40 mM), high-potassium (100 mM) medium. 2,4-dinitrophenol (10−4 M) reverses ouabain-induced inhibition of lactate and 14CO2 production but only partially reverses inhibition induced by Na+ + K+ deprivation, indicating that metabolic inhibition by ouabain is secondary to the inhibition of sodium transport. There is no synergism between Mecholyl and epinephrine. The absence of any significant inhibitory effects by acetazolamide (Diamox) or HCO3−-free media suggests that H+ transport may not be important in sweat gland function. In contrast to a report by Wolfe et al., human eccrine sweat glands show considerable oxidative activity (14CO2 production of 0.42-0.72 nmol/gland/h). These observations are discussed in terms of the linkage between sweat gland energy metabolism and sodium transport. PMID:4269528

  14. Widespread sites of brain stem ventilatory chemoreceptors.

    PubMed

    Coates, E L; Li, A; Nattie, E E

    1993-07-01

    We produced local tissue acidosis in various brain stem regions with 1-nl injections of acetazolamide (AZ) to locate the sites of central chemoreception. To determine whether the local acidosis resulted in a stimulation of breathing, we performed the experiment in chloralose-urethan anesthetized vagotomized carotid-denervated (cats) paralyzed servo-ventilated cats and rats and measured phrenic nerve activity (PNA) as the response index. Measurements of extracellular brain tissue pH by glass microelectrodes showed that AZ injections induced a change in pH at the injection center equivalent to that produced by an increase in end-tidal PCO2 of approximately 36 Torr and that the change in brain pH was limited to a tissue volume with a radius of < 350 microns. We found AZ injections sites that caused a significant increase in PNA to be located 1) within 800 microns of the ventrolateral medullary surface at locations within traditional rostral and caudal chemosensitive areas and the intermediate area, 2) within the vicinity of the nucleus tractus solitarii, and 3) within the vicinity of the locus coeruleus. Single AZ injections produced increases in PNA that were < or = 69% of the maximum value observed with an increase in end-tidal PCO2. We conclude that central chemoreceptors are distributed at many locations within the brain stem, all within 1.5 mm of the surface, and that stimulation of a small fraction of all central chemoreceptors can result in a large ventilatory response.

  15. Separation of carotid body chemoreceptor responses to O2 and CO2 by oligomycin and by antimycin A.

    PubMed

    Mulligan, E; Lahiri, S

    1982-03-01

    The cat carotid chemoreceptor O2 and CO2 responses can be separated by oligomycin and by antimycin A. Both of these agents greatly diminish or abolish the chemoreceptor O2 response but not the nicotine or CO2 responses. After either oligomycin or antimycin, the responses to increases and decreases in arterial CO2 partial pressure (PaCO2) consisted of increases and decreases in activity characterized respectively by exaggerated overshoots and undershoots. These were eliminated by the carbonic anhydrase inhibitor, acetazolamide, suggesting that they resulted from changes in carotid body tissue pH. The steady-state PaCO2 response remaining after oligomycin was no longer dependent on arterial O2 partial pressure (PaO2). All effects of antimycin were readily reversible in about 20 min. The separation of the responses to O2 and CO2 indicates that there may be at least partially separate pathways of chemoreception for these two stimuli. The similarity of the oligomycin and antimycin results supports the metabolic hypothesis of chemoreception.

  16. Altitude Stress During Participation of Medical Congress

    PubMed Central

    Kim, Soon Bae; Kim, Jong Sung; Kim, Sang Jun; Cho, Su Hee

    2016-01-01

    Medical congresses often held in highlands. We reviewed several medical issues associated with altitude stress especially while physicians have participated medical congress held in high altitude. Altitude stress, also known as an acute mountain sickness (AMS), is caused by acute exposure to low oxygen level at high altitude which is defined as elevations at or above 1,200 m and AMS commonly occurs above 2,500 m. Altitude stress with various symptoms including insomnia can also be experienced in airplane. AMS and drunken state share many common features in symptoms, neurologic manifestations and even show multiple microbleeds in corpus callosum and white matter on MRI. Children are more susceptible to altitude stress than adults. Gradual ascent is the best method for the prevention of altitude stress. Adequate nutrition (mainly carbohydrates) and hydration are recommended. Consumption of alcohol can exacerbate the altitude-induced impairments in judgment and the visual senses and promote psychomotor dysfunction. For prevention or treatment of altitude stress, acetazolamide, phosphodiesterase inhibitors, dexamethasone and erythropoietin are helpful. Altitude stress can be experienced relatively often during participation of medical congress. It is necessary to remind the harmful effect of AMS because it can cause serious permanent organ damage even though the symptoms are negligible in most cases. PMID:27621942

  17. Posterior Ciliary Artery Occlusion Caused by Hyaluronic Acid Injections Into the Forehead: A Case Report.

    PubMed

    Hu, Xiu Zhuo; Hu, Jun Yan; Wu, Peng Sen; Yu, Sheng Bo; Kikkawa, Don O; Lu, Wei

    2016-03-01

    Although cosmetic facial soft tissue fillers are generally safe and effective, improper injections can lead to devastating and irreversible consequences. We represent the first known case of posterior ciliary artery occlusion caused by hyaluronic acid. A 41-year-old female presented with right visual loss 7 hours after receiving cosmetic hyaluronic acid injections into her forehead. Examination revealed no light perception in the right eye and multiple dark ischemic area of injection over the forehead and nose. The right fundus revealed a pink retina with optic nerve edema. Fluorescein angiogram showed several filling defects in the choroidal circulation and late hyperfluorescence in the choroid. A right posterior ciliary artery occlusion and embolic occlusion of facial artery braches was diagnosed. With hyaluronidase injection, hyperbaric oxygen therapy, oral aspirin, oral acetazolamide and dexamethasone venotransfuse treatment, the patient's forehead and nasal skin improved and vision recovered to hand movements. With proper technique, vascular occlusion is rare following facial filler injection. Vision consequences can be severe if filler emboli enter the ocular circulation. Physicians should be aware of this potential side effect, recognize its presentation, and be knowledgeable of effective management.

  18. Mechanism of delayed intracranial hypertension after cerebroventricular infusions in conscious rats

    NASA Technical Reports Server (NTRS)

    Morrow, B. A.; Holt, M. R.; Starcevic, V. P.; Keil, L. C.; Severs, W. B.

    1992-01-01

    Prior studies showed that cerebroventricular infusions of artificial cerebrospinal fluid, 8 microliter/min for 10 min, followed by a 10 min rest and a 24 h infusion of 0.5 microliters/min, raised cerebrospinal fluid pressure (CSFp) of conscious, unrestrained rats after about 2 h. Here, we report that the 10 min infusion alone evoked a delayed, prolonged rise in CSFp. Pressure during the infusion itself rose and recovered quickly, as is usually reported. Pressure/volume tests, used to calculate resistance to outflow (Ro) and compliance (C), revealed that infusions increased Ro and decreased C, after a delay (P less than 0.05). The rise in CSFp after infusion was blocked by pretreatment with acetazolamide + ouabain (P less than 0.05), but the delayed changes in Ro and C were unaffected. We suggest that the 10 min infusion of a sterile, balanced salt solution has a primary effect that increases Ro; as CSF synthesis continues, C is exhausted and the delayed rise in CSFp ensues. This non-traumatic method of raising CSFp may be a useful method to study intracranial fluid dynamics.

  19. Respiratory control in residents at high altitude: physiology and pathophysiology.

    PubMed

    León-Velarde, Fabiola; Richalet, Jean-Paul

    2006-01-01

    Highland population (HA) from the Andes, living above 3000 m, have a blunted ventilatory response to increasing hypoxia, breathe less compared to acclimatized newcomers, but more, compared to sea-level natives at sea level. Subjects with chronic mountain sickness (CMS) breathe like sea-level natives and have excessive erythrocytosis (EE). The respiratory stimulation that arises through the peripheral chemoreflex is modestly less in the CMS group when compared with the HA group at the same P(ET(O2)). With regard to CO(2) sensitivity, CMS subjects seem to have reset their central CO(2) chemoreceptors to operate around the sea-level resting P(ET(CO2)). Acetazolamide, an acidifying drug that increases the chemosensitivity of regions in the brain stem that contain CO(2)/H(+) sensitive neurons, partially reverses this phenomenon, thus, providing CMS subjects with the possibility to have high CO(2) changes, despite small changes in ventilation. However, the same type of adjustments of the breathing pattern established for Andeans has not been found necessarily in Asian humans and/or domestic animals nor in the various high altitude species studied. The differing time frames of exposure to hypoxia among the populations, as well as the reversibility of the different components of the respiratory process at sea level, provide key concepts concerning the importance of time at high altitude in the evolution of an appropriate breathing pattern.

  20. Simultaneous recording of hippocampal oxygen and glucose in real time using constant potential amperometry in the freely-moving rat.

    PubMed

    Kealy, John; Bennett, Rachel; Lowry, John P

    2013-04-30

    Amperometric sensors for oxygen and glucose allow for real time recording from the brain in freely-moving animals. These sensors have been used to detect activity- and drug-induced changes in metabolism in a number of brain regions but little attention has been given over to the hippocampus despite its importance in cognition and disease. Sensors for oxygen and glucose were co-implanted into the hippocampus and allowed to record for several days. Baseline recordings show that basal concentrations of hippocampal oxygen and glucose are 100.26±5.76 μM and 0.60±0.06 mM respectively. Furthermore, stress-induced changes in neural activity have been shown to significantly alter concentrations of both analytes in the hippocampus. Administration of O2 gas to the animals' snouts results in significant increases in hippocampal oxygen and glucose and administration of N2 gas results in a significant decrease in hippocampal oxygen. Chloral hydrate-induced anaesthesia causes a significant increase in hippocampal oxygen whereas treatment with the carbonic anhydrase inhibitor acetazolamide significantly increases hippocampal oxygen and glucose. These findings provide real time electrochemical data for the hippocampus which has been previously impossible with traditional methods such as microdialysis or ex vivo analysis. As such, these sensors provide a window into hippocampal function which can be used in conjunction with behavioural and pharmacological interventions to further elucidate the functions and mechanisms of action of the hippocampus in normal and disease states.

  1. Idiopathic intracranial hypertension as an initial presentation of systemic lupus erythematosus

    PubMed Central

    Maloney, Keisha

    2013-01-01

    A 14-year-old girl with no known illness presented with a several week history of headaches and vomiting. The patient also reported having joint pain and swelling to the wrists and knees. She had no prior history of headaches, use of hormonal contraception or other medications, recent weight changes or family history of autoimmune disease. Blood pressure temperature, height and weight were normal. She was alert, there was alopecia, cervical lympadenopathy, symmetrical synovitis to the wrists, bilateral papilloedema and cranial nerve VI palsy. Laboratory investigations revealed a normochromic normocytic anaemia, leucopenia and lymphopenia. Serum chemistries were normal. CT of the brain was normal. Lumbar puncture revealed an opening pressure of greater than 300 mm H2O; cerebrospinal fluid (CSF) analysis was normal. HIV antibodies were non-reactive. Despite treatment with acetazolamide she developed somnolence. Hence MR venography was performed which showed no evidence of cerebral vein thrombosis. Further investigations revealed a positive direct coombs test, positive antinuclear antibodies (ANA) positive antidouble-stranded DNA (dsDNA) and false positive VDRL. Complement levels were reduced. Anti-Smith, anticardiolipin antibodies and lupus anticoagulant were negative. PMID:23943808

  2. Reassessment of sup 14 CO sub 2 compartmentation and of ( sup 14 C)formate oxidation in rat liver

    SciTech Connect

    Marsolais, C.; Lafreniere, F.; David, F.; Dodgson, S.J.; Brunengraber, H. )

    1989-11-25

    Our previous report had concluded that a fraction of ({sup 14}C)formate oxidation in liver occurs in the mitochondrion. This conclusion was based on the labeling patterns of urea and acetoacetate labeled via {sup 14}CO{sub 2} generated from ({sup 14}C)formate and other ({sup 14}C)substrates. We reassessed our interpretation in experiments conducted in (i) perifused mitochondria and (ii) isolated livers perfused with buffer containing ({sup 14}C)formate, ({sup 14}C)gluconolactone, {sup 14}CO{sub 2}, or NaH{sup 13}CO{sub 3}, in the absence and presence of acetazolamide, an inhibitor of carbonic anhydrase. Our data show that the cytosolic pools of bicarbonate and CO{sub 2} are not in isotopic equilibrium when {sup 14}CO{sub 2} is generated in the cytosol or is supplied as NaH{sup 14}CO3. We retract our earlier suggestion of a mitochondrial site of ({sup 14}C)formate oxidation.

  3. Acute occlusion of the retinal arteries: current concepts and recent advances in diagnosis and management

    PubMed Central

    Beatty, S; Eong, K

    2000-01-01

    Purpose/Background—Central retinal artery occlusion (CRAO) is usually a blinding event, and is not an infrequent presentation to the accident and emergency (A&E) department. The evidence-base in support of current treatment options is weak. Methods—This paper reviewed the literature germane to the diagnostic, therapeutic and prognostic aspects of retinal arterial occlusive disease. Results—The visual prognosis associated with CRAO remains poor, and current therapeutic practices are of unproven benefit. The non-ophthalmologist in the A&E department should lie the patient flat and give a stat dose of intravenous acetazolamide in an attempt to improve the retinal perfusion pressure. Conclusion—The management of acute occlusion of the central retinal artery has not changed over the past 30 years, although the potential benefits of superselective intra-arterial fibrinolytic therapy warrant evaluation in a randomised controlled trial. The identification of underlying pathology is an essential component of medical care, and all cases should be followed up by an ophthalmologist because of the possibility of ocular rubeosis. PMID:11005400

  4. Cerebrospinal fluid hypersecretion in pediatric hydrocephalus.

    PubMed

    Karimy, Jason K; Duran, Daniel; Hu, Jamie K; Gavankar, Charuta; Gaillard, Jonathan R; Bayri, Yasar; Rice, Hunter; DiLuna, Michael L; Gerzanich, Volodymyr; Marc Simard, J; Kahle, Kristopher T

    2016-11-01

    Hydrocephalus, despite its heterogeneous causes, is ultimately a disease of disordered CSF homeostasis that results in pathological expansion of the cerebral ventricles. Our current understanding of the pathophysiology of hydrocephalus is inadequate but evolving. Over this past century, the majority of hydrocephalus cases has been explained by functional or anatomical obstructions to bulk CSF flow. More recently, hydrodynamic models of hydrocephalus have emphasized the role of abnormal intracranial pulsations in disease pathogenesis. Here, the authors review the molecular mechanisms of CSF secretion by the choroid plexus epithelium, the most efficient and actively secreting epithelium in the human body, and provide experimental and clinical evidence for the role of increased CSF production in hydrocephalus. Although the choroid plexus epithelium might have only an indirect influence on the pathogenesis of many types of pediatric hydrocephalus, the ability to modify CSF secretion with drugs newer than acetazolamide or furosemide would be an invaluable component of future therapies to alleviate permanent shunt dependence. Investigation into the human genetics of developmental hydrocephalus and choroid plexus hyperplasia, and the molecular physiology of the ion channels and transporters responsible for CSF secretion, might yield novel targets that could be exploited for pharmacotherapeutic intervention.

  5. Long Term Amperometric Recordings in the Brain Extracellular Fluid of Freely Moving Immunocompromised NOD SCID Mice

    PubMed Central

    Reid, Caroline H.; Finnerty, Niall J.

    2017-01-01

    We describe the in vivo characterization of microamperometric sensors for the real-time monitoring of nitric oxide (NO) and oxygen (O2) in the striatum of immunocompromised NOD SCID mice. The latter strain has been utilized routinely in the establishment of humanized models of disease e.g., Parkinson’s disease. NOD SCID mice were implanted with highly sensitive and selective NO and O2 sensors that have been previously characterized both in vitro and in freely moving rats. Animals were systemically administered compounds that perturbed the amperometric current and confirmed sensor performance. Furthermore, the stability of the amperometric current was investigated and 24 h recordings examined. Saline injections caused transient changes in both currents that were not significant from baseline. l-NAME caused significant decreases in NO (p < 0.05) and O2 (p < 0.001) currents compared to saline. l-Arginine produced a significant increase (p < 0.001) in NO current, and chloral hydrate and Diamox (acetazolamide) caused significant increases in O2 signal (p < 0.01) compared against saline. The stability of both currents were confirmed over an eight-day period and analysis of 24-h recordings identified diurnal variations in both signals. These findings confirm the efficacy of the amperometric sensors to perform continuous and reliable recordings in immunocompromised mice. PMID:28241417

  6. Carbonic anhydrase activity in the vas deferens of the cotton leafworm - Spodoptera littoralis (Lepidoptera: Noctuidae) controlled by circadian clock.

    PubMed

    Kotwica, J; Ciuk, M A; Joachimiak, E; Rowinski, S; Cymborowski, B; Bebas, P

    2006-11-01

    The male reproductive tract of Lepidoptera is an ideal model for the study of the physiological role of peripheral clocks in insects. The latter are significant in the generation and coordination of rhythmic phenomena which facilitate the initial stages of sperm capacitation. This process requires the maintenance of pH in the upper vas deferens (UVD) aided by, among others, H+-ATPase. Our aim was to determine the potential involvement of carbonic anhydrase (CA) in this process, an enzyme tasked with generating protons subsequently utilized by H+-ATPase to acidify the UVD milieu in S. littoralis, during the time when the lumen of this organ is filled with sperm. We attempted to answer the question whether CA activity can be controlled by the biological oscillator present in the male reproductive tract of the cotton leafworm. Using PAGE zymography, the presence of CA was demonstrated in the UVD wall, but not in the luminal fluid nor in the sperm. Using histochemistry, it was shown that CA is active in the UVD epithelium, and that this activity varies throughout the day and is most likely controlled by an endogenous biological clock. Conversely, the application of CA inhibitors, acetazolamide and sodium thiocyanate, in conjunction with an analysis of H+-ATPase activity in the acidification the UVD environment shows that CA most likely does not play a direct role in the regulation of the pH in this organ.

  7. Expression and characterization of a codon-optimized alkaline-stable carbonic anhydrase from Aliivibrio salmonicida for CO2 sequestration applications.

    PubMed

    Jun, So-Young; Kim, Sung Ho; Kanth, Bashista Kumar; Lee, Jinwon; Pack, Seung Pil

    2017-03-01

    The CO2 mineralization process, accelerated by carbonic anhydrase (CA) was proposed for the efficient capture and storage of CO2, the accumulation of which in the atmosphere is the main cause of global warming. Here, we characterize a highly stable form of the cloned CA from the Gram-negative marine bacterium Aliivibrio salmonicida, named ASCA that can promote CO2 absorption in an alkaline solvent required for efficient carbon capture. We designed a mature form of ASCA (mASCA) using a codon optimization of ASCA gene and removal of ASCA signal peptide. mASCA was highly expressed (255 mg/L) with a molecular weight of approximately 26 kDa. The mASCA enzyme exhibited stable esterase activity within a temperature range of 10-60 °C and a pH range of 6-11. mASCA activity remained stable for 48 h at pH 10. We also investigated its inhibition profiles using inorganic anions, such as acetazolamide, sulfanilamide, iodide, nitrate, and azide. We also demonstrate that mASCA is capable of catalyzing the conversion of CO2 to CaCO3 (calcite form) in the presence of Ca(2+). It should be noted that mASCA enzyme exhibits high production yield and sufficient stabilities against relatively high temperature and alkaline pH, which are required conditions for the development of more efficient enzymatic CCS systems.

  8. Aqueous humor analysis after Nd:YAG laser capsulotomy with the laser flare-cell meter.

    PubMed

    Altamirano, D; Mermoud, A; Pittet, N; van Melle, G; Herbort, C P

    1992-11-01

    Using the laser flare-cell meter (Kowa FC-1000), we conducted a prospective study analyzing the effect of Nd:YAG posterior capsulotomy on the quantity of aqueous particles, aqueous flare, and intraocular pressure in 65 eyes (58 patients). Aqueous particles increased at six hours, followed by flare rise which was significant at 18 hours after capsulotomy. Only 22 eyes (34%) had a significant flare rise over prelaser values. Anti-inflammatory therapy was necessary in only one patient. The mean intraocular pressure value did not rise significantly after capsulotomy. Acute intraocular hypertension (AIOHT) (> 7 mm Hg increase) occurred between three and six hours after laser therapy in 12 patients (19%), was related in time to particle rise, and always responded to a single dose of acetazolamide. Acute intraocular hypertension was strongly correlated with elevated aqueous particles (P < .0001) and somewhat correlated with flare rise (P < .036), but was not correlated with the intraocular lens position (bag or sulcus fixation). Our findings strongly suggest that trabecular meshwork clogging by debris generated by the capsulotomy is the mechanism at the origin of AIOHT.

  9. Basolateral Cl- uptake mechanisms in Xenopus laevis lung epithelium.

    PubMed

    Berger, Jens; Hardt, Martin; Clauss, Wolfgang G; Fronius, Martin

    2010-07-01

    A thin liquid layer covers the lungs of air-breathing vertebrates. Active ion transport processes via the pulmonary epithelial cells regulate the maintenance of this layer. This study focuses on basolateral Cl(-) uptake mechanisms in native lungs of Xenopus laevis and the involvement of the Na(+)/K(+)/2 Cl(-) cotransporter (NKCC) and HCO(3)(-)/Cl(-) anion exchanger (AE), in particular. Western blot analysis and immunofluorescence staining revealed the expression of the NKCC protein in the Xenopus lung. Ussing chamber experiments demonstrated that the NKCC inhibitors (bumetanide and furosemide) were ineffective at blocking the cotransporter under basal conditions, as well as under pharmacologically stimulated Cl(-)-secreting conditions (forskolin and chlorzoxazone application). However, functional evidence for the NKCC was detected by generating a transepithelial Cl(-) gradient. Further, we were interested in the involvement of the HCO(3)(-)/Cl(-) anion exchanger to transepithelial ion transport processes. Basolateral application of DIDS, an inhibitor of the AE, resulted in a significantly decreased the short-circuit current (I(SC)). The effect of DIDS was diminished by acetazolamide and reduced by increased external HCO(3)(-) concentrations. Cl(-) secretion induced by forskolin was decreased by DIDS, but this effect was abolished in the presence of HCO(3)(-). These experiments indicate that the AE at least partially contributes to Cl(-) secretion. Taken together, our data show that in Xenopus lung epithelia, the AE, rather than the NKCC, is involved in basolateral Cl(-) uptake, which contrasts with the common model for Cl(-) secretion in pulmonary epithelia.

  10. Targeting carbonic anhydrase IX improves the anti-cancer efficacy of mTOR inhibitors

    PubMed Central

    Faes, Seraina; Planche, Anne; Uldry, Emilie; Santoro, Tania; Pythoud, Catherine; Stehle, Jean-Christophe; Horlbeck, Janine; Letovanec, Igor; Riggi, Nicolo; Datta, Dipak; Demartines, Nicolas; Dormond, Olivier

    2016-01-01

    The inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) by chemical inhibitors, such as rapamycin, has demonstrated anti-cancer activity in preclinical and clinical trials. Their efficacy is, however, limited and tumors eventually relapse through resistance formation. In this study, using two different cancer mouse models, we identify tumor hypoxia as a novel mechanism of resistance of cancer cells against mTORC1 inhibitors. Indeed, we show that the activity of mTORC1 is mainly restricted to the non-hypoxic tumor compartment, as evidenced by a mutually exclusive staining pattern of the mTORC1 activity marker pS6 and the hypoxia marker pimonidazole. Consequently, whereas rapamycin reduces cancer cell proliferation in non-hypoxic regions, it has no effect in hypoxic areas, suggesting that cancer cells proliferate independently of mTORC1 under hypoxia. Targeting the hypoxic tumor compartment by knockdown of carbonic anhydrase IX (CAIX) using short hairpin RNA or by chemical inhibition of CAIX with acetazolamide potentiates the anti-cancer activity of rapamycin. Taken together, these data emphasize that hypoxia impairs the anti-cancer efficacy of rapalogs. Therapeutic strategies targeting the hypoxic tumor compartment, such as the inhibition of CAIX, potentiate the efficacy of rapamycin and warrant further clinical evaluation. PMID:27153561

  11. Cerebral collateral therapeutics in acute ischemic stroke: A randomized preclinical trial of four modulation strategies.

    PubMed

    Beretta, Simone; Versace, Alessandro; Carone, Davide; Riva, Matteo; Dell'Era, Valentina; Cuccione, Elisa; Cai, Ruiyao; Monza, Laura; Pirovano, Silvia; Padovano, Giada; Stiro, Fabio; Presotto, Luca; Paternò, Giovanni; Rossi, Emanuela; Giussani, Carlo; Sganzerla, Erik P; Ferrarese, Carlo

    2017-01-01

    Cerebral collaterals are dynamically recruited after arterial occlusion and highly affect tissue outcome in acute ischemic stroke. We investigated the efficacy and safety of four pathophysiologically distinct strategies for acute modulation of collateral flow (collateral therapeutics) in the rat stroke model of transient middle cerebral artery (MCA) occlusion. A composed randomization design was used to assign rats (n = 118) to receive phenylephrine (induced hypertension), polygeline (intravascular volume load), acetazolamide (cerebral arteriolar vasodilation), head down tilt (HDT) 15° (cerebral blood flow diversion), or no treatment, starting 30 min after MCA occlusion. Compared to untreated animals, treatment with collateral therapeutics was associated with lower infarct volumes (62% relative mean difference; 51.57 mm(3) absolute mean difference; p < 0.001) and higher chance of good functional outcome (OR 4.58, p < 0.001). Collateral therapeutics acutely increased cerebral perfusion in the medial (+40.8%; p < 0.001) and lateral (+19.2%; p = 0.016) MCA territory compared to pretreatment during MCA occlusion. Safety indicators were treatment-related mortality and cardiorespiratory effects. The highest efficacy and safety profile was observed for HDT. Our findings suggest that acute modulation of cerebral collaterals is feasible and provides a tissue-saving effect in the hyperacute phase of ischemic stroke prior to recanalization therapy.

  12. Glaucoma Surgery in Pregnancy: A Case Series and Literature Review

    PubMed Central

    Razeghinejad, Mohammad Reza; Masoumpour, Masoumeh; Eghbal, Mohammad Hossein; Myers, Jonathan S.; Moster, Marlene R.

    2016-01-01

    Glaucoma management in pregnant patients is a real challenge, especially when the glaucoma is not controlled with medications. We report the results of 6 incisional glaucoma surgeries for the management of medically uncontrolled glaucoma patients during pregnancy. This retrospective, case series was conducted on the 6 eyes of 3pregnant patients with uncontrolled glaucoma using maximum tolerable medications. Details of the glaucoma surgical management of these patients as well as their postoperative care and pregnancy and clinical outcomes on longitudinal follow-up are discussed. All 3 patients had juvenile open-angle glaucoma and were on various anti-glaucoma medications, including oral acetazolamide. The first case described underwent trabeculectomy without antimetabolites in both eyes because of uncontrolled intraocular pressure with topical medications. The surgery was done with topical lidocaine jelly and subconjunctival lidocaine during the second and third trimesters. The second patient had an Ahmed valve implantation in both eyes during the second and third trimesters because of uncontrolled IOP with topical medications and no response to selective laser trabeculoplasty. Surgery was done with topical tetracaine and subconjunctival and sub-Tenon’s lidocaine. The third case had a Baerveldt valve implantation under general anesthesia in the second trimester. In selected pregnant glaucoma patients with medically uncontrolled intraocular pressure threatening vision, incisional surgery may lead to good outcomes for the patient with no risk for the fetus. PMID:27582594

  13. Major contribution of the type II beta carbonic anhydrase CanB (Cj0237) to the capnophilic growth phenotype of Campylobacter jejuni.

    PubMed

    Al-Haideri, Halah; White, Michael A; Kelly, David J

    2016-02-01

    Campylobacter jejuni, the leading cause of human bacterial gastroenteritis, requires low environmental oxygen and high carbon dioxide for optimum growth, but the molecular basis for the carbon dioxide requirement is unclear. One factor may be inefficient conversion of gaseous CO2 to bicarbonate, the required substrate of various carboxylases. Two putative carbonic anhydrases (CAs) are encoded in the genome of C. jejuni strain NCTC 11168 (Cj0229 and Cj0237). Here, we show that the deletion of the cj0237 (canB) gene alone prevents growth in complex media at low (1% v/v) CO2 and significantly reduces the growth rate at high (5% v/v) CO2. In minimal media incubated under high CO2, the canB mutant grew on L-aspartate but not on the key C3 compounds L-serine, pyruvate and L-lactate, showing that CanB is crucial in bicarbonate provision for pyruvate carboxylase-mediated oxaloacetate synthesis. Nevertheless, purified CanB (a dimeric, anion and acetazolamide sensitive, zinc-containing type II beta-class enzyme) hydrates CO2 actively only above pH 8 and with a high Km (∼ 34 mM). At typical cytoplasmic pH values and low CO2, these kinetic properties might limit intracellular bicarbonate availability. Taken together, our data suggest CanB is a major contributor to the capnophilic growth phenotype of C. jejuni.

  14. RNAi silencing of P/Q-type calcium channels in Purkinje neurons of adult mouse leads to episodic ataxia type 2.

    PubMed

    Salvi, Julie; Bertaso, Federica; Mausset-Bonnefont, Anne-Laure; Metz, Alexandra; Lemmers, Céline; Ango, Fabrice; Fagni, Laurent; Lory, Philippe; Mezghrani, Alexandre

    2014-08-01

    Episodic ataxia type-2 (EA2) is a dominantly inherited human neurological disorder caused by loss of function mutations in the CACNA1A gene, which encodes the CaV2.1 subunit of P/Q-type voltage-gated calcium channels. It remains however unknown whether the deficit of cerebellar CaV2.1 in adult is in direct link with the disease. To address this issue, we have used lentiviral based-vector RNA interference (RNAi) to knock-down CaV2.1 expression in the cerebellum of adult mice. We show that suppression of the P/Q-type channels in Purkinje neurons induced motor abnormalities, such as imbalance and ataxic gait. Interestingly, moderate channel suppression caused no basal ataxia, while β-adrenergic activation and exercise mimicked stress induced motor disorders. Moreover, stress-induced ataxia was stable, non-progressive and totally abolished by acetazolamide, a carbonic anhydrase inhibitor used to treat EA2. Altogether, these data reveal that P/Q-type channel suppression in adult mice supports the episodic status of EA2 disease.

  15. Congenital ataxia and hemiplegic migraine with cerebral edema associated with a novel gain of function mutation in the calcium channel CACNA1A.

    PubMed

    García Segarra, Nuria; Gautschi, Ivan; Mittaz-Crettol, Laureane; Kallay Zetchi, Christine; Al-Qusairi, Lama; Van Bemmelen, Miguel Xavier; Maeder, Philippe; Bonafé, Luisa; Schild, Laurent; Roulet-Perez, Eliane

    2014-07-15

    Mutations in the CACNA1A gene, encoding the α1 subunit of the voltage-gated calcium channel Ca(V)2.1 (P/Q-type), have been associated with three neurological phenotypes: familial and sporadic hemiplegic migraine type 1 (FHM1, SHM1), episodic ataxia type 2 (EA2), and spinocerebellar ataxia type 6 (SCA6). We report a child with congenital ataxia, abnormal eye movements and developmental delay who presented severe attacks of hemiplegic migraine triggered by minor head traumas and associated with hemispheric swelling and seizures. Progressive cerebellar atrophy was also observed. Remission of the attacks was obtained with acetazolamide. A de novo 3 bp deletion was found in heterozygosity causing loss of a phenylalanine residue at position 1502, in one of the critical transmembrane domains of the protein contributing to the inner part of the pore. We characterized the electrophysiology of this mutant in a Xenopus oocyte in vitro system and showed that it causes gain of function of the channel. The mutant Ca(V)2.1 activates at lower voltage threshold than the wild type. These findings provide further evidence of this molecular mechanism as causative of FHM1 and expand the phenotypic spectrum of CACNA1A mutations with a child exhibiting severe SHM1 and non-episodic ataxia of congenital onset.

  16. sup 14 C fixation by leaves and leaf cell protoplasts of the submerged aquatic angiosperm Potamogeton lucens: Carbon dioxide or bicarbonate

    SciTech Connect

    Staal, M.; Elzenga, J.T.M.; Prins, H.B.A. )

    1989-07-01

    Protoplasts were isolated from leaves of the aquatic angiosperm Potamogeton lucens L. The leaves utilize bicarbonate as a carbon source for photosynthesis, and show polarity; that is acidification of the periplasmic space of the lower, and alkalinization of the space near the upper leaf side. At present there are two models under consideration for this photosynthetic bicarbonate utilization process: conversion of bicarbonate into free carbon dioxide as a result of acidification and, second, a bicarbonate-proton symport across the plasma membrane. Carbon fixation of protoplasts was studied at different pH values and compared with that in leaf strips. Using the isotopic disequilibrium technique, it was established that carbon dioxide and not bicarbonate was the form in which DIC actually crossed the plasma membrane. It is concluded that there is probably no true bicarbonate transport system at the plasma membrane of these cells and that bicarbonate utilization in this species apparently rests on the conversion of bicarbonate into carbon dioxide. Experiments with acetazolamide, an inhibitor of periplasmic carbonic anhydrase, and direct measurements of carbonic anhydrase activity in intact leaves indicate that in this species the role of this enzyme for periplasmic conversion of bicarbonate into carbon dioxide is insignificant.

  17. Immobilization of carbonic anhydrase enzyme purified from Bacillus subtilis VSG-4 and its application as CO(2) sequesterer.

    PubMed

    Oviya, M; Giri, Sib Sankar; Sukumaran, V; Natarajan, P

    2012-01-01

    The purification, immobilization, and characterization of carbonic anhydrase (CA) secreted by Bacillus subtilis VSG-4 isolated from tropical soil have been investigated in this work. Carbonic anhydrase was purified using ammonium sulfate precipitation, Sephadex-G-75 column chromatography, and DEAE-cellulose chromatography, achieving a 24.6-fold purification. The apparent molecular mass of purified CA obtained by SDS-PAGE was found to be 37 kD. The purified CA was entrapped within a chitosan-alginate polyelectrolyte complex (C-A PEC) hydrogel for potential use as an immobilized enzyme. The optimum pH and temperature for both free and immobilized enzymes were 8.2 and 37°C, respectively. The immobilized enzyme had a much higher storage stability than the free enzyme. Certain metal ions, namely, Co(2+), Cu(2+), and Fe(3+), increased the enzyme activity, whereas CA activity was inhibited by Pb(2+), Hg(2+), ethylenediamine tetraacetic acid (EDTA), 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB), and acetazolamide. Free and immobilized CAs were tested further for the targeted application of the carbonation reaction to convert CO(2) to CaCO(3). The maximum CO(2) sequestration potential was achieved with immobilized CA (480 mg CaCO(3)/mg protein). These properties suggest that immobilized VSG-4 carbonic anhydrase has the potential to be used for biomimetic CO(2) sequestration.

  18. 'Wrong-way-round ionization' and screening for doping substances in human urine by high-performance liquid chromatography/orbitrap mass spectrometry.

    PubMed

    Virus, E D; Sobolevsky, T G; Rodchenkov, G M

    2012-03-01

    To free analytical resources for new classes of doping substances, such as banned proteins, maximization of the number of compounds that can be determined with high sensitivity in a single run is highly urgent. This study demonstrates an application of 'wrong-way-round ionization' for the simultaneous detection of multiple classes of doping substances without the need to switch the polarity. A screening method for the detection of 137 compounds from various classes of prohibited substances (stimulants, diuretics, β(2)-agonists, β-blockers, antiestrogens, glucocorticosteroids and anabolic agents) has been developed. The method involves an enzymatic hydrolysis, liquid-liquid extraction and detection by liquid chromatography/orbitrap mass spectrometry with wrong-way-round ionization. Up to 64% of compounds had a 10-fold lower limit of detection (LOD) than the minimum required performance limit. To compare the efficiency of conventional ionization relative to wrong-way-round ionization of doping substances in + ESI, a fortified blank urine sample at the minimum required performance limit was analyzed using two ESI approaches. All compounds were detected with markedly better S/N in a high-pH mobile phase, with the exception of acetazolamide (minimal change in S/N, < 20%).The method was validated by spiking 10 different blank urine samples at five different concentrations. Validation parameters included the LOD, selectivity, ion suppression, extraction recovery and repeatability.

  19. Exercise oscillatory ventilation: Mechanisms and prognostic significance

    PubMed Central

    Dhakal, Bishnu P; Lewis, Gregory D

    2016-01-01

    Alteration in breathing patterns characterized by cyclic variation of ventilation during rest and during exercise has been recognized in patients with advanced heart failure (HF) for nearly two centuries. Periodic breathing (PB) during exercise is known as exercise oscillatory ventilation (EOV) and is characterized by the periods of hyperpnea and hypopnea without interposed apnea. EOV is a non-invasive parameter detected during submaximal cardiopulmonary exercise testing. Presence of EOV during exercise in HF patients indicates significant impairment in resting and exercise hemodynamic parameters. EOV is also an independent risk factor for poor prognosis in HF patients both with reduced and preserved ejection fraction irrespective of other gas exchange variables. Circulatory delay, increased chemosensitivity, pulmonary congestion and increased ergoreflex signaling have been proposed as the mechanisms underlying the generation of EOV in HF patients. There is no proven treatment of EOV but its reversal has been noted with phosphodiesterase inhibitors, exercise training and acetazolamide in relatively small studies. In this review, we discuss the mechanistic basis of PB during exercise and the clinical implications of recognizing PB patterns in patients with HF. PMID:27022457

  20. Reduced Gut Acidity Induces an Obese-Like Phenotype in Drosophila melanogaster and in Mice

    PubMed Central

    Yen, Jui-Hung; Kuo, Ping-Chang; Yeh, Sheng-Rong; Lin, Hung-Yu; Fu, Tsai-Feng; Wu, Ming-Shiang; Wang, Horng-Dar; Wang, Pei-Yu

    2015-01-01

    In order to identify genes involved in stress and metabolic regulation, we carried out a Drosophila P-element-mediated mutagenesis screen for starvation resistance. We isolated a mutant, m2, that showed a 23% increase in survival time under starvation conditions. The P-element insertion was mapped to the region upstream of the vha16-1 gene, which encodes the c subunit of the vacuolar-type H+-ATPase. We found that vha16-1 is highly expressed in the fly midgut, and that m2 mutant flies are hypomorphic for vha16-1 and also exhibit reduced midgut acidity. This deficit is likely to induce altered metabolism and contribute to accelerated aging, since vha16-1 mutant flies are short-lived and display increases in body weight and lipid accumulation. Similar phenotypes were also induced by pharmacological treatment, through feeding normal flies and mice with a carbonic anhydrase inhibitor (acetazolamide) or proton pump inhibitor (PPI, lansoprazole) to suppress gut acid production. Our study may thus provide a useful model for investigating chronic acid suppression in patients. PMID:26436771

  1. Poly(amidoamine) dendrimers show carbonic anhydrase inhibitory activity against α-, β-, γ- and η-class enzymes.

    PubMed

    Carta, Fabrizio; Osman, Sameh M; Vullo, Daniela; AlOthman, Zeid; Del Prete, Sonia; Capasso, Clemente; Supuran, Claudiu T

    2015-11-01

    Four generations of poly(amidoamine) (PAMAM) dendrimers incorporating benzenesulfonamide moieties were investigated as inhibitors of carbonic anhydrases (CAs, EC 4.2.1.1) belonging to the α-, β-, γ- and η-classes which are present in pathogenic bacteria, fungi or protozoa. The following bacterial, fungal and protozoan organisms were included in the study: Vibrio cholerae, Trypanosoma cruzi, Leishmania donovani chagasi, Porphyromonas gingivalis, Cryptococcus neoformans, Candida glabrata, and Plasmodium falciparum. The eight pathozymes present in these organisms were efficiently inhibited by the four generations PAMAM-sulfonamide dendrimers, but multivalency effects were highly variable among the different enzyme classes. The Vibrio enzyme VchCA was best inhibited by the G3 dendrimer incorporating 32 sulfamoyl moieties. The Trypanosoma enzyme TcCA on the other hand was best inhibited by the first generation dendrimer G0 (with 4 sulfamoyl groups), whereas for other enzymes the optimal inhibitory power was observed for the G1 or G2 dendrimers, with 8 and 16 sulfonamide functionalities. This study thus proves that the multivalency may be highly relevant for enzyme inhibition for some but not all CAs from pathogenic organisms. On the other hand, some dendrimers investigated here showed a better inhibitory power compared to acetazolamide for enzymes from widespread pathogens, such as the η-CA from Plasmodium falciparum. Overall, the main conclusion is that this class of molecules may lead to important developments in the field of anti-infective CA inhibitors.

  2. The functional and physical relationship between the DRA bicarbonate transporter and carbonic anhydrase II.

    PubMed

    Sterling, Deborah; Brown, Nathan J D; Supuran, Claudiu T; Casey, Joseph R

    2002-11-01

    COOH-terminal cytoplasmic tails of chloride/bicarbonate anion exchangers (AE) bind cytosolic carbonic anhydrase II (CAII) to form a bicarbonate transport metabolon, a membrane protein complex that accelerates transmembrane bicarbonate flux. To determine whether interaction with CAII affects the downregulated in adenoma (DRA) chloride/bicarbonate exchanger, anion exchange activity of DRA-transfected HEK-293 cells was monitored by following changes in intracellular pH associated with bicarbonate transport. DRA-mediated bicarbonate transport activity of 18 +/- 1 mM H+ equivalents/min was inhibited 53 +/- 2% by 100 mM of the CAII inhibitor, acetazolamide, but was unaffected by the membrane-impermeant carbonic anhydrase inhibitor, 1-[5-sulfamoyl-1,3,4-thiadiazol-2-yl-(aminosulfonyl-4-phenyl)]-2,6-dimethyl-4-phenyl-pyridinium perchlorate. Compared with AE1, the COOH-terminal tail of DRA interacted weakly with CAII. Overexpression of a functionally inactive CAII mutant, V143Y, reduced AE1 transport activity by 61 +/- 4% without effect on DRA transport activity (105 +/- 7% transport activity relative to DRA alone). We conclude that cytosolic CAII is required for full DRA-mediated bicarbonate transport. However, DRA differs from other bicarbonate transport proteins because its transport activity is not stimulated by direct interaction with CAII.

  3. Regulation of renal peripheral benzodiazepine receptors by anion transport inhibitors

    SciTech Connect

    Basile, A.S.; Lueddens, W.M.; Skolnick, P.

    1988-01-01

    The in vitro and in vivo regulation of (/sup 3/H)Ro 5-4864 binding to peripheral benzodiazepine receptors (PBR) by ion transport/exchange inhibitors was studied in the kidney. The potencies of 9-anthroic acid, furosemide, bumetanide, hydrochlorothiazide and SITS as inhibitors of (/sup 3/H)Ro 5-4864 binding to renal membranes were consistent with their actions as anion transport inhibitors (Ki approx. = 30 - 130 ..mu..M). In contrast, spironolactone, amiloride, acetazolamide, and ouabain were less potent (Ki=100-1000 ..mu..M). Administration of furosemide to rats for five days resulted in a profound diuresis accompanied by a significant increase in PBR density (43%) that was apparent by the fifth day of treatment. Administration of hydrochlorothiazide or Ro 5-4864 for five days also caused diuresis and increased renal PBR density. Both the diuresis and increased density of PBR produced by Ro 5-4864 were blocked by coadministration of PK 11195, which alone had no effect on either PBR density or urine volume. The equilibrium binding constants of (/sup 3/H)Ro 5-4864 to cardiac membranes were unaffected by administration of any of these drugs. These findings suggest that renal PBR may be selectively modulated in vivo and in vitro by administration of ion transport/exchange inhibitors. 36 references, 4 tables.

  4. Macromolecular Drug Targets in Cancer Treatment and Thiosemicarbazides as Anticancer Agents.

    PubMed

    Küçükgüzel, Ş Güniz; Coşkun, Göknil P

    2016-01-01

    Cancer is known as abnormal cell division and consisting of a group of diseases on various organ tissues. Many therapies are available in cancer treatment such as chemotherapy, radiotherapy etc. Without damaging normal tissue, there is a huge need for specified anticancer drugs which have effect only on abnormal cancer cells. Therefore, advances in anticancer drug discovery in treating cancer in the recent years, directed towards to the macromolecular targets. Heterocyclic molecules, such as fluconazole, acetazolamide, etc., have a significant role in health care and pharmaceutical drug design. Thiosemicarbazides (NH2-NH-CSNH2) are the simplest hydrazine derivatives of thiocarbamic acid and are not only transition compounds, but they are also very effective organic compounds. Thiosemicarbazides possess an amide and amine protons, carbonyl and thione carbons. These structures have attracted the attention of the researchers in the development of novel compounds with anticonvulsant, antiviral, anti-inflammatory, antibacterial, antimycobacterial, antifungal, antioxidant and anticancer activities. Recently, a number of thiosemicarbazides are available commercially as anticancer drugs for novel anticancer drug discovery. Antineoplastic or anticancer drugs prevent or inhibit the maturation and proliferation of neoplasms. These observations have been guiding the researchers for the development of new thiosemicarbazides that possess anticancer activity.

  5. Consensus Paper: Management of Degenerative Cerebellar Disorders

    PubMed Central

    Ilg, W.; Bastian, A. J.; Boesch, S.; Burciu, R. G.; Celnik, P.; Claaßen, J.; Feil, K.; Kalla, R.; Miyai, I.; Nachbauer, W.; Schöls, L.; Strupp, M.; Synofzik, M.; Teufel, J.

    2015-01-01

    Treatment of motor symptoms of degenerative cerebellar ataxia remains difficult. Yet there are recent developments that are likely to lead to significant improvements in the future. Most desirable would be a causative treatment of the underlying cerebellar disease. This is currently available only for a very small subset of cerebellar ataxias with known metabolic dysfunction. However, increasing knowledge of the pathophysiology of hereditary ataxia should lead to an increasing number of medically sensible drug trials. In this paper, data from recent drug trials in patients with recessive and dominant cerebellar ataxias will be summarized. There is consensus that up to date, no medication has been proven effective. Aminopyridines and acetazolamide are the only exception, which are beneficial in patients with episodic ataxia type 2. Aminopyridines are also effective in a subset of patients presenting with downbeat nystagmus. As such, all authors agreed that the mainstays of treatment of degenerative cerebellar ataxia are currently physiotherapy, occupational therapy, and speech therapy. For many years, well-controlled rehabilitation studies in patients with cerebellar ataxia were lacking. Data of recently published studies show that coordinative training improves motor function in both adult and juvenile patients with cerebellar degeneration. Given the well-known contribution of the cerebellum to motor learning, possible mechanisms underlying improvement will be outlined. There is consensus that evidence-based guidelines for the physiotherapy of degenerative cerebellar ataxia need to be developed. Future developments in physiotherapeutical interventions will be discussed including application of non-invasive brain stimulation. PMID:24222635

  6. Isothermal titration calorimetry for drug design: Precision of the enthalpy and binding constant measurements and comparison of the instruments.

    PubMed

    Linkuvienė, Vaida; Krainer, Georg; Chen, Wen-Yih; Matulis, Daumantas

    2016-12-15

    Isothermal titration calorimetry (ITC) is one of the most robust label- and immobilization-free techniques used to measure protein - small molecule interactions in drug design for the simultaneous determination of the binding affinity (ΔG) and the enthalpy (ΔH), both of which are important parameters for structure-thermodynamics correlations. It is important to evaluate the precision of the method and of various ITC instrument models by performing a single well-characterized reaction. The binding between carbonic anhydrase II and acetazolamide was measured by four ITC instruments - PEAQ-ITC, iTC200, VP-ITC, and MCS-ITC and the standard deviation of ΔG and ΔH was determined. Furthermore, the limit of an approach to reduce the protein concentration was studied for a high-affinity reaction (Kd = 0.3 nM), too tight to be measured by direct (non-displacement) ITC. Chemical validation of the enthalpy measurements is discussed.

  7. Bilateral acute closed angle glaucoma associated with the discontinuation of escitalopram: a case report

    PubMed Central

    AlQuorain, Sara; Alfaraj, Sukayna; Alshahrani, Mohammed

    2016-01-01

    A 45-year-old woman presented to the Emergency Department complaining of severe headache for 3 hours duration associated with bilateral blurred vision, photophobia, and one attack of vomiting. Her clinical examination revealed normal vital signs and decrease in visual acuity with hazy cornea bilaterally. There were no signs of increased intracranial pressure and no neck rigidity or meningeal signs. The patient was diagnosed with bilateral acute closed angle glaucoma (AACG) with intraocular pressure of 60 mmHg in both eyes. She was using escitalopram for the treatment of depression, which was the only known risk factor for her condition. Standard treatment for AACG was provided. It included topical β-blocker, α agonists, and acetazolamide. This was followed by bilateral peripheral iridotomy. Follow-up intraocular pressure measurement revealed a value of 5 mmHg after 24 hours, indicating complete recovery. To the best of our knowledge, this is the first case to describe AACG after stopping the medication. It is highly important that clinicians be aware of this risk factor for AACG and have high index of suspicion in such patients with vision-threatening condition even after discontinuing the medication, because the risk persists for some time. PMID:27660499

  8. [Contribution to the problem of preventing recurrences of oxalate and phosphate urinary caluli: active modification of citrate excretion and Ca++-binding capacity in the urine of Wistar rats].

    PubMed

    Leskovar, P; Hropot, M; Wellnhofer, E; Scherm, D; Schade, K L

    1982-03-01

    Citric acid may well be, quantitatively and in terms of complex chemistry, the most important of the organic acids capable of binding Ca++ in urine. Since the quantitative determination of citrates in urine became a routine method in many research-orientated urological laboratories thanks to the introduction of standardized enzymatic tests, reports of a reduced excretion of citrates in patients with (recurrent) (oxalate) calculi have become frequent. During our long-term study of patients with recurrent formation of calculi we also observed a clear deficit of citrates in their morning, midday and evening urine. The conspicuous incidence of calculi when there is a concurrence of hypocitraturia and alkaline urine (RTA, in animal experiments: acetazolamide) clearly suggests the lithoprotective significance of citric acid. By quantitatively testing a large number of organic compounds which are interesting both structurally and in terms of complex chemistry, it has been possible to find some substances which restrict crystallization, raise the level of citrates and bind Ca++. A few have also found to restrict the excretion of oxalate in Wistar rats.

  9. Wilderness medicine at high altitude: recent developments in the field

    PubMed Central

    Shah, Neeraj M; Hussain, Sidra; Cooke, Mark; O’Hara, John P; Mellor, Adrian

    2015-01-01

    Travel to high altitude is increasingly popular. With this comes an increased incidence of high-altitude illness and therefore an increased need to improve our strategies to prevent and accurately diagnose these. In this review, we provide a summary of recent advances of relevance to practitioners who may be advising travelers to altitude. Although the Lake Louise Score is now widely used as a diagnostic tool for acute mountain sickness (AMS), increasing evidence questions the validity of doing so, and of considering AMS as a single condition. Biomarkers, such as brain natriuretic peptide, are likely correlating with pulmonary artery systolic pressure, thus potential markers of the development of altitude illness. Established drug treatments include acetazolamide, nifedipine, and dexamethasone. Drugs with a potential to reduce the risk of developing AMS include nitrate supplements, propagators of nitric oxide, and supplemental iron. The role of exercise in the development of altitude illness remains hotly debated, and it appears that the intensity of exercise is more important than the exercise itself. Finally, despite copious studies demonstrating the value of preacclimatization in reducing the risk of altitude illness and improving performance, an optimal protocol to preacclimatize an individual remains elusive. PMID:26445563

  10. Whole-exome sequencing as a diagnostic tool in a family with episodic ataxia type 1

    PubMed Central

    Tacik, Pawel; Guthrie, Kimberly J.; Strongosky, Audrey J.; Broderick, Daniel F.; Riegert-Johnson, Douglas L.; Tang, Sha; El-Khechen, Dima; Parker, Alexander S.; Ross, Owen A.; Wszolek, Zbigniew K.

    2015-01-01

    Complex neurological phenotypes are inherently difficult to diagnose. Whole-exome sequencing (WES) is a new tool in the neurologist's diagnostic armamentarium. WES can be applied to investigate the “diagnostic odyssey” cases. These cases involve patients with rare diseases of likely genetic etiology who have failed to obtain a diagnosis by clinical evaluation and targeted gene testing. The 22-year-old adopted proband presented with episodes of jerking ataxic movements that affected his whole body and mild intellectual developmental disability. He underwent numerous multidisciplinary and multicentric evaluations throughout his life that failed to establish a clear diagnosis. Following his visit to the Mayo Clinic, WES was applied for genetic determination of the unknown disorder in the proband, his biological parents and sister. Besides, four other paternal relatives were reported to have similar complaints. Additional clinical evaluation, and magnetic resonance neuroimaging (MRI), electromyography (EMG) and electroencephalography (EEG) of the proband were performed to verify the phenotype after the WES results were available. Eleven months after the proband's initial visit, WES identified the c.1210G>A (p.V404I) mutation in the potassium voltage-gated channel, shaker-related subfamily, member 1 gene in the proband, his father, and his sister, and thus the diagnosis of episodic ataxia type 1 was established. The proband's MRI demonstrated mild vermian hypoplasia, EMG myokymic discharges, and EEG generalized background slowing. Acetazolamide therapy was beneficial for him at the daily dose of 500 mg. PMID:25659636

  11. Practical aspects in the management of hypokalemic periodic paralysis

    PubMed Central

    Levitt, Jacob O

    2008-01-01

    Management considerations in hypokalemic periodic paralysis include accurate diagnosis, potassium dosage for acute attacks, choice of diuretic for prophylaxis, identification of triggers, creating a safe physical environment, peri-operative measures, and issues in pregnancy. A positive genetic test in the context of symptoms is the gold standard for diagnosis. Potassium chloride is the favored potassium salt given at 0.5–1.0 mEq/kg for acute attacks. The oral route is favored, but if necessary, a mannitol solvent can be used for intravenous administration. Avoidance of or potassium prophylaxis for common triggers, such as rest after exercise, high carbohydrate meals, and sodium, can prevent attacks. Chronically, acetazolamide, dichlorphenamide, or potassium-sparing diuretics decrease attack frequency and severity but are of little value acutely. Potassium, water, and a telephone should always be at a patient's bedside, regardless of the presence of weakness. Perioperatively, the patient's clinical status should be checked frequently. Firm data on the management of periodic paralysis during pregnancy is lacking. Patient support can be found at . PMID:18426576

  12. Bicarbonate-water interactions in the rat proximal convoluted tubule. An effect of volume flux on active proton secretion

    PubMed Central

    1984-01-01

    The effect of volume absorption on bicarbonate absorption was examined in the in vivo perfused rat proximal convoluted tubule. Volume absorption was inhibited by isosmotic replacement of luminal NaCl with raffinose. In tubules perfused with 25 mM bicarbonate, as raffinose was increased from 0 to 55 to 63 mM, volume absorption decreased from 2.18 +/- 0.10 to 0.30 +/- 0.18 to -0.66 +/- 0.30 nl/mm X min, respectively, and bicarbonate absorption decreased from 131 +/- 5 to 106 +/- 8 to 91 +/- 13 pmol/mm X min, respectively. This bicarbonate-water interaction could not be attributed to dilutional changes in luminal or peritubular bulk phase bicarbonate concentrations. Inhibition of active proton secretion by acetazolamide abolished the effect of volume flow on bicarbonate absorption, which implies that the bicarbonate reflection coefficient is close to 1 and eliminates the possibility of solvent drag across the tight junction. When the luminal bicarbonate concentration was varied, the magnitude of the bicarbonate-water interaction increased with increasing luminal bicarbonate concentration. The largest interaction occurred at high luminal bicarbonate concentrations, where the rate of proton secretion has been previously shown to be independent of luminal bicarbonate concentration and pH. The results thus suggest that a peritubular and/or cellular compartment exists that limits bicarbonate diffusion, and where pH changes secondary to bicarbonate-water interactions (solute polarization) alter the rate of active proton secretion. PMID:6096481

  13. Regulation of statoconia mineralization in Aplysia californica in vitro

    NASA Technical Reports Server (NTRS)

    Pedrozo, H. A.; Schwartz, Z.; Dean, D. D.; Wiederhold, M. L.; Boyan, B. D.

    1996-01-01

    Statoconia are calcium carbonate inclusions in the lumen of the gravity-sensing organ, the statocyst, of Aplysia californica. The aim of the present study was to examine the role of carbonic anhydrase and urease in statoconia mineralization in vitro. The experiments were performed using a previously described culture system (Pedrozo et al., J. Comp. Physiol. (A) 177:415-425). Inhibition of carbonic anhydrase by acetazolamide decreased statoconia production and volume, while inhibition of urease by acetohydroxamic acid reduced total statoconia number, but had no affect on statoconia volume. Inhibition of carbonic anhydrase initially increased and then decreased the statocyst pH, whereas inhibition of urease decreased statocyst pH at all times examined; simultaneous addition of both inhibitors also decreased pH. These effects were dose and time dependent. The results show that carbonic anhydrase and urease are required for statoconia formation and homeostasis, and for regulation of statocyst pH. This suggests that these two enzymes regulate mineralization at least partially through regulation of statocyst pH.

  14. Carbonic anhydrase, a respiratory enzyme in the gills of the shore crab Carcinus maenas

    NASA Astrophysics Data System (ADS)

    Böttcher, K.; Siebers, D.; Sender, S.

    1995-03-01

    This paper summarizes investigations on the enzyme carbonic anhydrase (CA) in the gills of the osmoregulating shore crab Carcinus maenas. Carbonic anhydrase, an enzyme catalyzing the reversible hydration of CO2 to HCO3 - and H+, is localized with highest activities in the posterior salt-transporting gills of the shore crab- and here CA activity is strongly dependent on salinity. Contrary to the earlier hypothesis established for the blue crab Callinectes sapidus that cytoplasmic branchial CA provides the counter ions HCO3 - and H+ for apical exchange against Na+ and Cl-, the involvement of CA in NaCl uptake mechanisms can be excluded in Carcinus. Differential and density gradient centrifugations indicate that branchial CA is a predominantly membrane-associated protein. Branchial CA was greatly inhibited by the sulfonamide acetazolamide (AZ) Ki=2.4·10-8 mol/l). Using the preparation of the isolated perfused gill, application of 10-4 mol/l AZ resulted in an 80% decrease of CO2/HCO3 - excretion. Thus we conclude that CA is localized in plasma membranes, maintaining the CO2 gradient by accelerating adjustment of the pH-dependent CO2/HCO3 - equilibrium.

  15. Evidence for the involvement of carbonic anhydrase and urease in calcium carbonate formation in the gravity-sensing organ of Aplysia californica

    NASA Technical Reports Server (NTRS)

    Pedrozo, H. A.; Schwartz, Z.; Dean, D. D.; Harrison, J. L.; Campbell, J. W.; Wiederhold, M. L.; Boyan, B. D.

    1997-01-01

    To better understand the mechanisms that could modulate the formation of otoconia, calcium carbonate granules in the inner ear of vertebrate species, we examined statoconia formation in the gravity-sensing organ, the statocyst, of the gastropod mollusk Aplysia californica using an in vitro organ culture model. We determined the type of calcium carbonate present in the statoconia and investigated the role of carbonic anhydrase (CA) and urease in regulating statocyst pH as well as the role of protein synthesis and urease in statoconia production and homeostasis in vitro. The type of mineral present in statoconia was found to be aragonitic calcium carbonate. When the CA inhibitor, acetazolamide (AZ), was added to cultures of statocysts, the pH initially (30 min) increased and then decreased. The urease inhibitor, acetohydroxamic acid (AHA), decreased statocyst pH. Simultaneous addition of AZ and AHA caused a decrease in pH. Inhibition of urease activity also reduced total statoconia number, but had no effect on statoconia volume. Inhibition of protein synthesis reduced statoconia production and increased statoconia volume. In a previous study, inhibition of CA was shown to decrease statoconia production. Taken together, these data show that urease and CA play a role in regulating statocyst pH and the formation and maintenance of statoconia. CA produces carbonate ion for calcium carbonate formation and urease neutralizes the acid formed due to CA action, by production of ammonia.

  16. Carbonic anhydrase XII is a new therapeutic target to overcome chemoresistance in cancer cells

    PubMed Central

    Jacobs, Andrea; Frei, Andreas P.; Ghigo, Dario; Wollscheid, Bernd; Riganti, Chiara

    2015-01-01

    Multidrug resistance (MDR) in cancer cells is a challenging phenomenon often associated with P-glycoprotein (Pgp) surface expression. Finding new ways to bypass Pgp-mediated MDR still remains a daunting challenge towards the successful treatment of malignant neoplasms such as colorectal cancer. We applied the Cell Surface Capture technology to chemosensitive and chemoresistant human colon cancer to explore the cell surface proteome of Pgp-expressing cells in a discovery-driven fashion. Comparative quantitative analysis of identified cell surface glycoproteins revealed carbonic anhydrase type XII (CAXII) to be up-regulated on the surface of chemoresistant cells, similarly to Pgp. In cellular models showing an acquired MDR phenotype due to the selective pressure of chemotherapy, the progressive increase of the transcription factor hypoxia-inducible factor-1 alpha was paralleled by the simultaneous up-regulation of Pgp and CAXII. CAXII and Pgp physically interacted at the cell surface. CAXII silencing or pharmacological inhibition with acetazolamide decreased the ATPase activity of Pgp by altering the optimal pH at which Pgp operated and promoted chemosensitization to Pgp substrates in MDR cells. We propose CAXII as a new secondary marker of the MDR phenotype that influences Pgp activity directly and can be used as a pharmacological target for MDR research and potential treatment. PMID:25686827

  17. Changes in body fluid compartments on re-induction to high altitude and effect of diuretics

    NASA Astrophysics Data System (ADS)

    Singh, M. V.; Rawal, S. B.; Tyagi, A. K.; Bhagat, Maj J. K.; Parshad, R.; Divekar, H. M.

    1988-03-01

    Studies were carried out in 29 healthy young adults in the Indian Army stationed in the plains and posted at an elevation of 3500 m for more than 6 months. After exposure to a low elevation in Delhi (260 m) for 3 weeks they were reinduced to a height of 3500 m. The subjects were divided into three groups, each of which was treated with either placebo or acetazolamide or spironolactone. The drug treatment was started immediately after their landing at high altitude and continued for 2 days only. Total body water, extracellular fluid, intracellular fluid, plasma volume, blood pH, PaO2, PaCO2 and blood viscosity were determined on exposure at Delhi and on re-induction to high altitude. Plasma volume was increased after the descent from high altitude and remained high for up to 21 day's study. This increased plasma volume may have some significance in the pathogenesis of pulmonary oedema. Total body water and intracellular fluid content were increased at 260 m elevation, while extracellular fluid decreased. On re-induction there was a decrease in total body water with no change in the extracellular fluid content.

  18. Synthesis, characterization and in vitro inhibition of metal complexes of pyrazole based sulfonamide on human erythrocyte carbonic anhydrase isozymes I and II.

    PubMed

    Büyükkıdan, Nurgün; Büyükkıdan, Bülent; Bülbül, Metin; Kasımoğulları, Rahmi; Mert, Samet

    2017-12-01

    Sulfonamides represent an important class of biologically active compounds. A sulfonamide possessing carbonic anhydrase (CA) inhibitory properties obtained from a pyrazole based sulfonamide, ethyl 1-(3-nitrophenyl)-5-phenyl-3-((5-sulfamoyl-1,3,4-thiadiazol-2-yl)carbamoyl)-1H-pyrazole-4-carboxylate (1), and its metal complexes with the Ni(II) for (2), Cu(II) for (3) and Zn(II) for (4) have been synthesized. The structures of metal complexes (2-4) were established on the basis of their elemental analysis, (1)H NMR, IR, UV-Vis and MS spectral data. The inhibition of two human carbonic anhydrase (hCA, EC 4.2.1.1) isoenzymes I and II, with 1 and synthesized complexes (2-4) and acetazolamide (AAZ) as a control compound was investigated in vitro by using the hydratase and esterase assays. The complexes 2, 3 and 4 showed inhibition constant in the range 0.1460-0.3930 µM for hCA-I and 0.0740-0.0980 µM for hCA-II, and they had effective more inhibitory activity on hCA-I and hCA-II than corresponding free ligand 1 and than AAZ.

  19. Isatin-pyrazole benzenesulfonamide hybrids potently inhibit tumor-associated carbonic anhydrase isoforms IX and XII.

    PubMed

    Ibrahim, Hany S; Abou-Seri, Sahar M; Tanc, Muhammet; Elaasser, Mahmoud M; Abdel-Aziz, Hatem A; Supuran, Claudiu T

    2015-10-20

    New series of benzenesulfonamide derivatives incorporating pyrazole and isatin moieties were prepared using celecoxib as lead molecule. Biological evaluation of the target compounds was performed against the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) and more precisely against the human isoforms hCA I, II (cytosolic), IX and XII (transmembrane, tumor-associated enzymes). Most of the tested compounds efficiently inhibited hCA I, II and IX, with KIs of 2.5-102 nM, being more effective than the reference drug acetazolamide. Compounds 11e, 11f, 16e and 16f were found to inhibit hCA XII with Ki of 3.7, 6.5, 5.4 and 7.2 nM, respectively. Compounds 11e and 16e, with 5-NO2 substitution on the isatin ring, were found to be selective inhibitors of hCA IX and hCA XII. Docking studies revealed that the NO2 group of both compounds participate in interactions with Asp132 within the hCA IX active site, and with residues Lys67 and Asp130 in hCA XII, respectively.

  20. Neurocognitive Dysfunction According to Hypoperfusion Territory in Patients With Moyamoya Disease

    PubMed Central

    2017-01-01

    Objective To demonstrate the prevalence of cerebral hypoperfusion without focal cerebral lesions in patients with Moyamoya disease (MMD), and the relationship between areas of hypoperfusion and cognitive impairment. Methods Twenty-six MMD patients were included. Patients were categorized according to the presence/absence of hypoperfusion in the frontal, parietal, temporal, and occipital lobes on brain single-photon-emission computed tomography (SPECT) after acetazolamide challenge. Computerized neuropsychological test (CNT) results were compared between groups. Results Only 3 patients showed normal cerebral perfusion. Baseline characteristics were similar between groups. Patients with frontal lobe hypoperfusion showed lower scores in visual continuous performance test (CPT), auditory CPT, forward digit span test, backward digit span test, verbal learning test, and trail-making test. Patients with parietal lobe hypoperfusion showed lower backward digit span test, visual learning test, and trail-making test scores. Related to temporal and occipital lobes, there were no significant differences in CNT results between the hypoperfusion and normal groups. Conclusion MMD patients without focal cerebral lesion frequently exhibit cerebral hypoperfusion. MMD patients with frontal and parietal hypoperfusion had abnormal CNT profiles, similar to those with frontal and parietal lesions. It is suggested that the hypoperfusion territory on brain SPECT without focal lesion may affect the characteristics of neurocognitive dysfunction in MMD patients. PMID:28289629

  1. Entry and exit pathways of CO2 in rat liver mitochondria respiring in a bicarbonate buffer system.

    PubMed

    Balboni, E; Lehninger, A L

    1986-03-15

    The dynamics and pathways of CO2 movements across the membranes of mitochondria respiring in vitro in a CO2/HCO-3 buffer at concentrations close to that in intact rat tissues were continuously monitored with a gas-permeable CO2-sensitive electrode. O2 uptake and pH changes were monitored simultaneously. Factors affecting CO2 entry were examined under conditions in which CO2 uptake was coupled to electrophoretic influx of K+ (in the presence of valinomycin) or Ca2+. The role of mitochondrial carbonic anhydrase (EC 4.2.1.1) in CO2 entry was evaluated by comparison of CO2 uptake by rat liver mitochondria, which possess carbonic anhydrase, versus rat heart mitochondria, which lack carbonic anhydrase. Such studies showed that matrix carbonic anhydrase activity is essential for rapid net uptake of CO2 with K+ or Ca2+. Studies with acetazolamide (Diamox), a potent inhibitor of carbonic anhydrase, confirmed the requirement of matrix carbonic anhydrase for net CO2 uptake. It was shown that at pH 7.2 the major species leaving respiring mitochondria is dissolved CO2, rather than HCO-3 or H2CO3 suggested by earlier reports. Efflux of endogenous CO2/HCO-3 is significantly inhibited by inhibitors of the dicarboxylate and tricarboxylate transport systems of the rat liver inner membrane. The possibility that these anion carriers mediate outward transport of HCO-3 is discussed.

  2. Varicella Zoster Aseptic Meningitis: Report of an Atypical Case and Literature Review

    PubMed Central

    Ibrahim, Walid; Elzouki, Abdel-Naser; Husain, Ahmed; Osman, Lubna

    2015-01-01

    Patient: Female, 15 Final Diagnosis: Varicella Zoster aseptic meningitis Symptoms: — Medication: — Clinical Procedure: Lumber punctur Specialty: Infectious Diseases Objective: Unusual clinical course Background: Neurologic complications can occur with varicella zoster virus (VZV) infection, usually after vesicular exanthem. A review of the literature revealed 3 cases of viral meningitis associated with 6th nerve palsy but without significantly increased intracranial pressure. Case Report: We report a case of a previously healthy 15-year-old girl with aseptic meningitis as a result of reactivated-VZV infection with symptoms of increased intracranial pressure and reversible 6th cranial nerve palsy but without exanthema. Diagnosis was made by detection of VZV-DNA in cerebrospinal fluid using polymerase chain reaction and documented high intracranial pressure. Full recovery was achieved after a course of acyclovir and acetazolamide. Conclusions: This case demonstrates that VZV may be considered in cases of aseptic meningitis in immunocompetent individuals, even without exanthema, and it may increase the intracranial pressure, leading to symptoms, and causing reversible neurological deficit. PMID:26342350

  3. Unilateral Meniere's disease: is the contralateral ear normal?

    PubMed

    Brookes, G B; Morrison, A W; Richard, R

    1985-11-01

    Certain investigations in patients with unilateral Meniere's disease may on occasion show abnormalities in the completely symptomless contralateral ear. These tests include transtympanic electrocochleography, the acetazolamide cochlear hydration test, vestibular aqueduct tomography, and caloric testing. Eventually these ears may well become symptomatic. Previous studies have shown that otoadmittance changes are a sensitive indicator of glycerol-induced intracochlear pressure alterations in hydropic ears, but do not occur in patients without Meniere's disease. Otoadmittance parameters were evaluated in the asymptomatic ears of 73 consecutive patients with unilateral Meniere's disease. Satisfactory traces and adequate dehydration were achieved in fifty-nine. A significant change in the maximum conductance, similar to that often seen in symptomatic hydropic ears, was found in twenty-four cases (40.7%). The presence of functional abnormalities in well over one-third of asymptomatic ears means that they cannot be used as controls in clinical research studies. Furthermore, recognition of contralateral latent hydrops at the initial otologic assessment may modify the subsequent treatment strategy.

  4. Characterization and inhibition studies of carbonic anhydrase from gill of Russian Sturgeon Fish (Acipenser gueldenstaedtii).

    PubMed

    Dinçer, Barbaros; Ekinci, Arife Pınar; Akyüz, Gülay; Kurtoğlu, İlker Zeki

    2016-12-01

    An α-carbonic anhydrase (CA, EC 4.2.1.1) was purified and characterized kinetically from gill of Acipenser gueldenstaedtii as an endangered sturgeon species. The carbonic anhydrase was purified 66-folds with yield 20.7% by Sepharose-4B-l-tyrosine-sulfanilamide affinity column and the specific activity was determined as 222.2 EU/mg protein. Km and Vmax kinetic values for gill carbonic anhydrase were calculated by a Lineweaver-Burk graph using p-nitrophenol acetate (p-NPA) as a substrate, and was defined as 2.5 mM and 5 × 10(6 )μM/min, respectively. It was observed that CA from the sturgeon gill in the presence of the sulfanilamide and acetazolamide as an inhibitor had very low IC50 values such as 13.0 and 0.1 μM, respectively. In addition, it was determined that the enzyme was inhibited by Fe(2+,) Co(2+,) Ni(2+), and Zn(2+)-Ba(2+) with the IC50 values of 0.2, 1.7, 1.2, and 1.1 mM, respectively.

  5. Effect of loop diuretics on cholinergic neurotransmission in human airways in vitro.

    PubMed Central

    Verleden, G. M.; Pype, J. L.; Deneffe, G.; Demedts, M. G.

    1994-01-01

    BACKGROUND--Frusemide can inhibit various indirectly acting bronchoconstrictor stimuli in asthmatic patients. Both frusemide and bumetanide also modulate airway neurotransmission in some species but there are no data on the effect of loop diuretics on neurotransmission in man. An in vitro study was performed in human airways to investigate the possible neuromodulatory action of two loop diuretics, frusemide and bumetanide, and to elucidate whether a cyclooxygenase inhibitor such as indomethacin could modulate the effect of frusemide. The effect of acetazolamide, a carbonic anhydrase inhibitor, was also investigated. METHODS--Electrical field stimulation (EFS; 40 V, 0.5 ms, 0.5-32 Hz for 15 seconds) in human airways with or without epithelium was used to induce a cholinergic contraction (n = 5 in all experiments). Indomethacin was present throughout. After obtaining a control frequency-response curve, different concentrations of diuretic were added to the organ bath and another frequency-response curve was constructed. To determine whether the effect of the diuretic was prejunctional or postjunctional a cumulative concentration-response curve to exogenous acetylcholine (Ach, 0.3 mumol/l to 10 mmol/l) was constructed in the presence of a diuretic (frusemide 1 mmol/l or bumetanide 0.1 mmol/l) or its vehicle. In some experiments indomethacin was omitted from the organ bath to investigate the possible involvement of cyclooxygenase products. RESULTS--Both frusemide (10 mumol/l to 1 mmol/l) and bumetanide (1 mumol/l to 0.1 mmol/l) produced a concentration-dependent inhibition of the EFS-induced cholinergic contraction in human airways in vitro but only in epithelium denuded tissues. Frusemide (1 mmol/l) produced a maximum inhibition of 46.3% (SE 9.9%) at 0.5 Hz and bumetanide (0.1 mmol/l 39.6 (6.2)% at 0.5 Hz. Without indomethacin in the organ bath the frusemide-induced inhibition was enhanced at 4, 8, and 16 Hz, but bumetanide-induced inhibition was not enhanced at any

  6. Induction of carbonic anhydrase in SaOS-2 cells, exposed to bicarbonate and consequences for calcium phosphate crystal formation.

    PubMed

    Müller, Werner E G; Schröder, Heinz C; Schlossmacher, Ute; Grebenjuk, Vlad A; Ushijima, Hiroshi; Wang, Xiaohong

    2013-11-01

    Ca-phosphate/hydroxyapatite crystals constitute the mineralic matrix of vertebrate bones, while Ca-carbonate dominates the inorganic matrix of otoliths. In addition, Ca-carbonate has been identified in lower percentage in apatite crystals. By using the human osteogenic SaOS-2 cells it could be shown that after exposure of the cells to Ca-bicarbonate in vitro, at concentrations between 1 and 10 mm, a significant increase of Ca-deposit formation results. The crystallite nodules formed on the surfaces of SaOS-2 cells become denser and larger in the presence of bicarbonate if simultaneously added together with the mineralization activation cocktail (β-glycerophosphate/ascorbic acid/dexamethasone). In parallel, with the increase of Ca-deposit formation, the expression of the carbonic anhydrase-II (CA-II) gene becomes upregulated. This effect, measured on transcriptional level is also substantiated by immunohistological studies. The stimulatory effect of bicarbonate on Ca-deposit formation is prevented if the carbonic anhydrase inhibitor acetazolamide is added to the cultures. Mapping the surface of the Ca-deposit producing SaOS-2 cells by scanning electron microscopy coupled with energy-dispersive X-ray analysis revealed an accumulation of the signals for the element carbon and, as expected, also for phosphorus. Finally, it is shown that ortho-phosphate and hydrolysis products of polyphosphate inhibit CA-II activity, suggesting a feedback regulatory system between the CA-driven Ca-carbonate deposition and a subsequent inactivation of this process by ortho-phosphate. Based on the presented data we suggest that Ca-carbonate deposits act as bioseeds for a downstream Ca-phosphate deposition process. We propose that activators for CA, especially for CA-II, might be beneficial for the treatment of bone deficiency diseases.

  7. [Adult-onset ataxia-telangiectasia. A clinical and therapeutic observation].

    PubMed

    Gazulla, J; Benavente, I; Sarasa Barrio, M

    2006-10-01

    A case of adult-onset ataxia-telangiectasia (AT) is presented, with debut at the age of 18 years and survival into the fourth decade. The clinical picture included cerebellar ataxia, distal weakness and hypopalesthesia in the lower limbs, oculomotor apraxia, dysarthria, and conjunctival telangiectasiae. Carcinoembrionic antigen was raised in plasma. MR imaging showed atrophy of the cerebellar vermis and thinning of the spinal cord. Deficiencies of gamma-aminobutyric acid and glutamate have been found in the cerebellar cortex in a case of AT. These were attributed to the loss of Purkinje cells and granule cells. In spite of some ataxias having improved with the gabaergic drugs gabapentin and tiagabine, the administration of gabapentin, acetazolamide and a placebo, did not benefit this patient. Pregabalin, 225 mg/day, ameliorated the ataxia unexpectedly, with further improvement after the addition of tiagabine. The authors suggest that the beneficial effect observed might have been due, either to the higher affinity of pregabalin towards alpha2-delta, a subtype of the alpha2-delta subunit which forms part of the voltage-gated calcium channel; either to the profusion of this subtype in the Purkinje cell layer, or to its larger capacity to let calcium into the neuron; or to the combination of these. These differences with gabapentin could explain the higher power of pregabalin in the stimulation of the cerebellar structures, thus justifying the improvement of ataxia in this case of AT. A synergistic effect with pregabalin is proposed as the cause of the improvement obtained with the addition of tiagabine.

  8. Chiral separation of new sulfonamide derivatives and evaluation of their enantioselective affinity for human carbonic anhydrase II by microscale thermophoresis and surface plasmon resonance.

    PubMed

    Rogez-Florent, Tiphaine; Foulon, Catherine; Drucbert, Anne-Sophie; Schifano, Nadège; Six, Perrine; Devassine, Stéphanie; Depreux, Patrick; Danzé, Pierre-Marie; Goossens, Laurence; Danel, Cécile; Goossens, Jean-François

    2017-04-15

    The aim of this study was to develop a method combining chiral separation and biophysical techniques to evaluate the enantioselective affinity of original sulfonamide derivatives towards their therapeutic target, the human carbonic anhydrase II (hACII). The first step consisted in the preparation of the enantiomers by chromatographic separation. The performances of HPLC and Supercritical Fluid Chromatography (SFC) were studied at the analytical scale by optimization of various experimental conditions using adsorbed polysaccharide chiral stationary phases (amylose AD-H and cellulose OD-H). Since SFC allowed obtaining higher enantioresolutions per time unit, it was selected for the semi-preparative scale and successfully used to isolate each enantiomer with a satisfactory enantiomeric purity (>98%). Secondly, microscale thermophoresis (MST) method and surface plasmon resonance (SPR) used as reference method were developed to measure potential enantioselective affinities of these enantiomers towards the hACII. The optimizations of both methods were performed using a reference compound, i.e. acetazolamide, which affinity for hCAII has previously been demonstrated. For all compounds, KD values obtained using MST and SPR were in good agreement, leading to similar affinity scales despite both approaches totally differ (labeling for MST versus immobilization of the protein for SPR). The equilibrium dissociation constants of our original compounds for the hCAII were in the range 100-1000nM and an enantioselectivity was observed using the MST and SPR methods for the diarylpyrazole 2. Finally, by comparing the MST and SPR techniques, MST appears especially adapted for further screening of a series of sulfonamide derivatives due to the lower time required to estimate a binding constant while consuming as little hCAII as SPR.

  9. Genetic enhancement of microsomal epoxide hydrolase improves metabolic detoxification but impairs cerebral blood flow regulation.

    PubMed

    Marowsky, Anne; Haenel, Karen; Bockamp, Ernesto; Heck, Rosario; Rutishauser, Sibylle; Mule, Nandkishor; Kindler, Diana; Rudin, Markus; Arand, Michael

    2016-12-01

    Microsomal epoxide hydrolase (mEH) is a detoxifying enzyme for xenobiotic compounds. Enzymatic activity of mEH can be greatly increased by a point mutation, leading to an E404D amino acid exchange in its catalytic triad. Surprisingly, this variant is not found in any vertebrate species, despite the obvious advantage of accelerated detoxification. We hypothesized that this evolutionary avoidance is due to the fact that the mEH plays a dualistic role in detoxification and control of endogenous vascular signaling molecules. To test this, we generated mEH E404D mice and assessed them for detoxification capacity and vascular dynamics. In liver microsomes from these mice, turnover of the xenobiotic compound phenanthrene-9,10-oxide was four times faster compared to WT liver microsomes, confirming accelerated detoxification. mEH E404D animals also showed faster metabolization of a specific class of endogenous eicosanoids, arachidonic acid-derived epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). Significantly higher DHETs/EETs ratios were found in mEH E404D liver, urine, plasma, brain and cerebral endothelial cells compared to WT controls, suggesting a broad impact of the mEH mutant on endogenous EETs metabolism. Because EETs are strong vasodilators in cerebral vasculature, hemodynamics were assessed in mEH E404D and WT cerebral cortex and hippocampus using cerebral blood volume (CBV)-based functional magnetic resonance imaging (fMRI). Basal CBV0 levels were similar between mEH E404D and control mice in both brain areas. But vascular reactivity and vasodilation in response to the vasodilatory drug acetazolamide were reduced in mEH E404D forebrain compared to WT controls by factor 3 and 2.6, respectively. These results demonstrate a critical role for mEH E404D in vasodynamics and suggest that deregulation of endogenous signaling pathways is the undesirable gain of function associated with the E404D variant.

  10. High-altitude Pulmonary Hypertension: an Update on Disease Pathogenesis and Management

    PubMed Central

    Mirrakhimov, Aibek E.; Strohl, Kingman P.

    2016-01-01

    High-altitude pulmonary hypertension (HAPH) affects individuals residing at altitudes of 2,500 meters and higher. Numerous pathogenic variables play a role in disease inception and progression and include low oxygen concentration in inspired air, vasculopathy, and metabolic abnormalities. Since HAPH affects only some people living at high altitude genetic factors play a significant role in its pathogenesis. The clinical presentation of HAPH is nonspecific and includes fatigue, shortness of breath, cognitive deficits, cough, and in advanced cases hepatosplenomegaly and overt right-sided heart failure. A thorough history is important and should include a search for additional risk factors for lung disease and pulmonary hypertension (PH) such as smoking, indoor air pollution, left-sided cardiac disease and sleep disordered breathing. Twelve-lead electrocardiogram, chest X-ray and echocardiography can be used as screening tools. A definitive diagnosis should be made with right-sided heart catheterization using a modified mean pulmonary artery pressure of at least 30 mm Hg, differing from the 25 mm Hg used for other types of PH. Treatment of HAPH includes descent to a lower altitude whenever possible, oxygen therapy and the use of medications such as endothelin receptor antagonists, phosphodiesterase 5 blockers, fasudil and acetazolamide. Some recent evidence suggests that iron supplementation may also be beneficial. However, it is important to note that the scientific literature lacks long-term randomized controlled data on the pharmacologic treatment of HAPH. Thus, an individualized approach to treatment and informing the patients regarding the benefits and risks of the selected treatment regimen are essential. PMID:27014374

  11. Decrease of intracellular pH as possible mechanism of embryotoxicity of glycol ether alkoxyacetic acid metabolites.

    PubMed

    Louisse, Jochem; Bai, Yanqing; Verwei, Miriam; van de Sandt, Johannes J M; Blaauboer, Bas J; Rietjens, Ivonne M C M

    2010-06-01

    Embryotoxicity of glycol ethers is caused by their alkoxyacetic acid metabolites, but the mechanism underlying the embryotoxicity of these acid metabolites is so far not known. The present study investigates a possible mechanism underlying the embryotoxicity of glycol ether alkoxyacetic acid metabolites using the methoxyacetic acid (MAA) metabolite of ethylene glycol monomethyl ether as the model compound. The results obtained demonstrate an MAA-induced decrease of the intracellular pH (pH(i)) of embryonic BALB/c-3T3 cells as well as of embryonic stem (ES)-D3 cells, at concentrations that affect ES-D3 cell differentiation. These results suggest a mechanism for MAA-mediated embryotoxicity similar to the mechanism of embryotoxicity of the drugs valproic acid and acetazolamide (ACZ), known to decrease the pH(i)in vivo, and therefore used as positive controls. The embryotoxic alkoxyacetic acid metabolites ethoxyacetic acid, butoxyacetic acid and phenoxyacetic acid also caused an intracellular acidification of BALB/c-3T3 cells at concentrations that are known to inhibit ES-D3 cell differentiation. Two other embryotoxic compounds, all-trans-retinoic acid and 5-fluorouracil, did not decrease the pH(i) of embryonic cells at concentrations that affect ES-D3 cell differentiation, pointing at a different mechanism of embryotoxicity of these compounds. MAA and ACZ induced a concentration-dependent inhibition of ES-D3 cell differentiation, which was enhanced by amiloride, an inhibitor of the Na(+)/H(+)-antiporter, corroborating an important role of the pH(i) in the embryotoxic mechanism of both compounds. Together, the results presented indicate that a decrease of the pH(i) may be the mechanism of embryotoxicity of the alkoxyacetic acid metabolites of the glycol ethers.

  12. V-H+ -ATPase translocation during blood alkalosis in dogfish gills: interaction with carbonic anhydrase and involvement in the postfeeding alkaline tide.

    PubMed

    Tresguerres, Martin; Parks, Scott K; Wood, Chris M; Goss, Greg G

    2007-05-01

    We investigated the involvement of carbonic anhydrase (CA) in mediating V-H(+)-ATPase translocation into the basolateral membrane in gills of alkalotic Squalus acanthias. Immunolabeling revealed that CA is localized in the same cells as V-H(+)-ATPase. Blood plasma from dogfish injected with acetazolamide [30 mg/kg at time (t) = 0 and 6 h] and infused with NaHCO(3) for 12 h (1,000 microeq.kg(-1).h(-1)) had significantly higher plasma HCO(3)(-) concentration than fish that were infused with NaHCO(3) alone (28.72 +/- 0.41 vs. 6.57 +/- 2.47 mmol/l, n = 3), whereas blood pH was similar in both treatments (8.03 +/- 0.11 vs. 8.04 +/- 0.11 pH units at t = 12 h). CA inhibition impaired V-H(+)-ATPase translocation into the basolateral membrane, as estimated from immunolabeled gill sections and Western blotting on gill cell membranes (0.24 +/- 0.08 vs. 1.00 +/- 0.28 arbitrary units, n = 3; P < 0.05). We investigated V-H(+)-ATPase translocation during a postfeeding alkalosis ("alkaline tide"). Gill samples were taken 24-26 h after dogfish were fed to satiety in a natural-like feeding regime. Immunolabeled gill sections revealed that V-H(+)-ATPase translocated to the basolateral membrane in the postfed fish. Confirming this result, V-H(+)-ATPase abundance was twofold higher in gill cell membranes of the postfed fish than in fasted fish (n = 4-5; P < 0.05). These results indicate that 1) intracellular H(+) or HCO(3)(-) produced by CA (and not blood pH or HCO(3)(-)) is likely the stimulus that triggers the V-H(+)-ATPase translocation into the basolateral membrane in alkalotic fish and 2) V-H(+)-ATPase translocation is important for enhanced HCO(3)(-) secretion during a naturally occurring postfeeding alkalosis.

  13. Physiological and Molecular Biological Characterization of Intracellular Carbonic Anhydrase from the Marine Diatom Phaeodactylum tricornutum1

    PubMed Central

    Satoh, Dan; Hiraoka, Yasutaka; Colman, Brian; Matsuda, Yusuke

    2001-01-01

    A single intracellular carbonic anhydrase (CA) was detected in air-grown and, at reduced levels, in high CO2-grown cells of the marine diatom Phaeodactylum tricornutum (UTEX 642). No external CA activity was detected irrespective of growth CO2 conditions. Ethoxyzolamide (0.4 mm), a CA-specific inhibitor, severely inhibited high-affinity photosynthesis at low concentrations of dissolved inorganic carbon, whereas 2 mm acetazolamide had little effect on the affinity for dissolved inorganic carbon, suggesting that internal CA is crucial for the operation of a carbon concentrating mechanism in P. tricornutum. Internal CA was purified 36.7-fold of that of cell homogenates by ammonium sulfate precipitation, and two-step column chromatography on diethylaminoethyl-sephacel and p-aminomethylbenzene sulfone amide agarose. The purified CA was shown, by SDS-PAGE, to comprise an electrophoretically single polypeptide of 28 kD under both reduced and nonreduced conditions. The entire sequence of the cDNA of this CA was obtained by the rapid amplification of cDNA ends method and indicated that the cDNA encodes 282 amino acids. Comparison of this putative precursor sequence with the N-terminal amino acid sequence of the purified CA indicated that it included a possible signal sequence of up to 46 amino acids at the N terminus. The mature CA was found to consist of 236 amino acids and the sequence was homologous to β-type CAs. Even though the zinc-ligand amino acid residues were shown to be completely conserved, the amino acid residues that may constitute a CO2-binding site appeared to be unique among the β-CAs so far reported. PMID:11500545

  14. [Central alveolar hypoventilation with cor pulmonale: successful treatment by non-invasive intermittent positive pressure ventilation].

    PubMed

    Montiel, G C; Roncoroni, A J; Quadrelli, S A; De Vito, E L

    1994-01-01

    A 62 year-old woman with a bilateral carotid body paraganglioma presented, 2 years after the removal of the right one, with signs of right-heart failure. Hypoxemia, hypercapnia, polycythemia and pulmonary hypertension with normal ventilatory capacity were found. Central alveolar hypoventilation was diagnosed on the basis of absence of ventilatory response and sensation of provoked hypercapnia, prolonged breath-holding time and correction of hypercapnia by voluntary ventilation. Progesterone (200 mg/d during 3 weeks) or naloxone did not improve either arterial blood gases (ABG) or the P 0.1/PCO2 curve. Hypoxemia and hypercapnia were not corrected during metabolic acidosis provoked by acetazolamide (250 mg/d). Nasal CPAP did not control hypoventilation periods. Mechanical ventilation was initiated with negative pressure (NPV) through a poncho. The patient presented severe discomfort with NPV and obstructive apneas were verified during it. She refused to continue NPV. Mechanical ventilation was initiated with positive intermittent pressure (IPPV) through a nasal mask. The patient had excellent tolerance to the procedure. SpO2 during IPPV was always higher than 95%. During sleep induction (under IPPV), respiration in phase with the ventilator 1: 1 was observed; instead, during consolidated sleep there was a complete dependence of the ventilator with apnea for over 2 min when IPPV was interrupted (Fig. 1). After 2 months of treatment, a relief of right ventricular failure occurred and hematocrit fell to 39%. There was an improvement of day-time ABG (Table I). The P. 0.1/PaCO2 curve 3 months after IPPV was the same as the previous one (Fig. 2). The patient has been for 18 months on home ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Carbonic anhydrase inhibition blocks skeletogenesis and echinochrome production in Paracentrotus lividus and Heliocidaris tuberculata embryos and larvae.

    PubMed

    Zito, Francesca; Koop, Demian; Byrne, Maria; Matranga, Valeria

    2015-09-01

    Carbonic anhydrases (CAs) are a family of widely distributed metalloenzymes, involved in diverse physiological processes. These enzymes catalyse the reversible conversion of carbon dioxide to protons and bicarbonate. At least 19 genes encoding for CAs have been identified in the sea urchin genome, with one of these localized to the skeletogenic mesoderm (primary mesenchyme cells, PMCs). We investigated the effects of a specific inhibitor of CA, acetazolamide (AZ), on development of two sea urchin species with contrasting investment in skeleton production, Paracentrotus lividus and Heliocidaris tuberculata, to determine the role of CA on PMC differentiation, skeletogenesis and on non-skeletogenic mesodermal (NSM) cells. Embryos were cultured in the presence of AZ from the blastula stage prior to skeleton formation and development to the larval stage was monitored. At the dose of 8 mmol/L AZ, 98% and 90% of P. lividus and H. tuberculata embryos lacked skeleton, respectively. Nevertheless, an almost normal PMC differentiation was indicated by the expression of msp130, a PMC-specific marker. Strikingly, the AZ-treated embryos also lacked the echinochrome pigment produced by the pigment cells, a subpopulation of NSM cells with immune activities within the larva. Conversely, all ectoderm and endoderm derivatives and other subpopulations of mesoderm developed normally. The inhibitory effects of AZ were completely reversed after removal of the inhibitor from the medium. Our data, together with new information concerning the involvement of CA on skeleton formation, provide evidence for the first time of a possible role of the CAs in larval immune pigment cells.

  16. A Carbonic Anhydrase Serves as an Important Acid-Base Regulator in Pacific Oyster Crassostrea gigas Exposed to Elevated CO2: Implication for Physiological Responses of Mollusk to Ocean Acidification.

    PubMed

    Wang, Xiudan; Wang, Mengqiang; Jia, Zhihao; Qiu, Limei; Wang, Lingling; Zhang, Anguo; Song, Linsheng

    2017-02-01

    Carbonic anhydrases (CAs) have been demonstrated to play an important role in acid-base regulation in vertebrates. However, the classification and modulatory function of CAs in marine invertebrates, especially their responses to ocean acidification remain largely unknown. Here, a cytosolic α-CA (designated as CgCAII-1) was characterized from Pacific oyster Crassostrea gigas and its molecular activities against CO2 exposure were investigated. CgCAII-1 possessed a conserved CA catalytic domain, with high similarity to invertebrate cytoplasmic or mitochondrial α-CAs. Recombinant CgCAII-1 could convert CO2 to HCO3(-) with calculated activity as 0.54 × 10(3) U/mg, which could be inhibited by acetazolamide (AZ). The mRNA transcripts of CgCAII-1 in muscle, mantle, hepatopancreas, gill, and hemocytes increased significantly after exposure to elevated CO2. CgCAII-1 could interact with the hemocyte membrane proteins and the distribution of CgCAII-1 protein became more concentrated and dense in gill and mantle under CO2 exposure. The intracellular pH (pHi) of hemocytes under CO2 exposure increased significantly (p < 0.05) and CA inhibition reduced the pHi value. Besides, there was no increase in CA activity in gill and mantle after CO2 exposure. The impact of CO2 exposure on CA activity coupled with the mRNA expression level and protein translocation of CgCAII-1 provided evidences that CgCAII-1 could respond to ocean acidification and participate in acid-base regulation. Such cytoplasmic CA-based physiological regulation mechanism might explain other physiological responses of marine organisms to OA.

  17. Anion inhibition study of the β-carbonic anhydrase (CahB1) from the cyanobacterium Coleofasciculus chthonoplastes (ex-Microcoleus chthonoplastes).

    PubMed

    Vullo, Daniela; Kupriyanova, Elena V; Scozzafava, Andrea; Capasso, Clemente; Supuran, Claudiu T

    2014-03-01

    We investigated the catalytic activity and inhibition of the β-class carbonic anhydrase (CA, EC 4.2.1.1) CahB1, from the relict cyanobacterium Coleofasciculus chthonoplastes (previously denominated Microcoleus chthonoplastes). The enzyme showed good activity as a catalyst for the CO2 hydration, with a kcat of 2.4 × 10(5)s(-1) and a kcat/Km of 6.3 × 10(7)M(-1)s(-1). A range of inorganic anions and small molecules were investigated as inhibitors of CahB1. Perchlorate and tetrafluoroborate did not inhibit the enzyme (KIs >200 mM) whereas selenate and selenocyanide were ineffective inhibitors too, with KIs of 29.9-48.61 mM. The halides, pseudohalides, carbonate, bicarbonate, trithiocarbonate and a range of heavy metal ions-containing anions were submillimolar-millimolar inhibitors (KIs in the range of 0.15-0.90 mM). The best CahB1 inhibitors were N,N-diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid and phenylarsonic acid, with KIs in the range of 8-75 μM, whereas acetazolamide inhibited the enzyme with a KI of 76 nM. This is the first kinetic and inhibition study of a cyanobacterial CA. As these enzymes are widespread in many cyanobacteria, being crucial for the carbon concentrating mechanism which assures substrate to RubisCO for the CO2 fixation by these organisms, a detailed kinetic/inhibition study may be essential for a better understanding of this superfamily of metalloenzymes and for potential biotechnological applications in biomimetic CO2 capture processes.

  18. Screening procedure for detection of diuretics and uricosurics and/or their metabolites in human urine using gas chromatography-mass spectrometry after extractive methylation.

    PubMed

    Beyer, Jochen; Bierl, Anabelle; Peters, Frank T; Maurer, Hans H

    2005-08-01

    A gas chromatography-mass spectrometry (GC-MS)-based screening procedure was developed for the detection of diuretics, uricosurics, and/or their metabolites in human urine after extractive methylation. Phase-transfer catalyst remaining in the organic phase was removed by solid-phase extraction on a diol phase. The compounds were separated by GC and identified by MS in the full-scan mode. The possible presence of the following drugs and/or their metabolites could be indicated using mass chromatography with the given ions: m/z 267, 352, 353, 355, 386, and 392 for thiazide diuretics bemetizide, bendroflumethiazide, butizide, chlorothiazide, cyclopenthiazide, cyclothiazide, hydrochlorothiazide, metolazone, polythiazide, and for canrenoic acid and spironolactone; m/z 77, 81, 181, 261, 270, 295, 406, and 438 for loop diuretics bumetanide, ethacrynic acid, furosemide, piretanide, torasemide, as well as the uricosurics benzbromarone, probenecid, and sulfinpyrazone; m/z 84, 85, 111, 112, 135, 161, 249, 253, 289, and 363 for the other diuretics acetazolamide, carzenide, chlorthalidone, clopamide, diclofenamide, etozoline, indapamide, mefruside, tienilic acid, and xipamide. The identity of positive signals in such mass chromatograms was confirmed by comparison of the peaks underlying full mass spectra with reference spectra. This method allowed the detection of the abovementioned drugs and/or their metabolites in human urine samples, except torasemide. The limits of detection ranged from 0.001 to 5 mg/L in the full-scan mode. Recoveries of selected diuretics and uricosurics, representing the different chemical classes, ranged from 46% to 99% with coefficients of variation of less than 21%. After ingestion of the lowest therapeutic doses, furosemide was detectable in urine samples for 67 hours, hydrochlorothiazide for 48 hours, and spironolactone for 52 hours (via its target analyte canrenone). The procedure described here is part of a systematic toxicological analysis

  19. Crystal structure and functional characterization of photosystem II-associated carbonic anhydrase CAH3 in Chlamydomonas reinhardtii.

    PubMed

    Benlloch, Reyes; Shevela, Dmitriy; Hainzl, Tobias; Grundström, Christin; Shutova, Tatyana; Messinger, Johannes; Samuelsson, Göran; Sauer-Eriksson, A Elisabeth

    2015-03-01

    In oxygenic photosynthesis, light energy is stored in the form of chemical energy by converting CO2 and water into carbohydrates. The light-driven oxidation of water that provides the electrons and protons for the subsequent CO2 fixation takes place in photosystem II (PSII). Recent studies show that in higher plants, HCO3 (-) increases PSII activity by acting as a mobile acceptor of the protons produced by PSII. In the green alga Chlamydomonas reinhardtii, a luminal carbonic anhydrase, CrCAH3, was suggested to improve proton removal from PSII, possibly by rapid reformation of HCO3 (-) from CO2. In this study, we investigated the interplay between PSII and CrCAH3 by membrane inlet mass spectrometry and x-ray crystallography. Membrane inlet mass spectrometry measurements showed that CrCAH3 was most active at the slightly acidic pH values prevalent in the thylakoid lumen under illumination. Two crystal structures of CrCAH3 in complex with either acetazolamide or phosphate ions were determined at 2.6- and 2.7-Å resolution, respectively. CrCAH3 is a dimer at pH 4.1 that is stabilized by swapping of the N-terminal arms, a feature not previously observed in α-type carbonic anhydrases. The structure contains a disulfide bond, and redox titration of CrCAH3 function with dithiothreitol suggested a possible redox regulation of the enzyme. The stimulating effect of CrCAH3 and CO2/HCO3 (-) on PSII activity was demonstrated by comparing the flash-induced oxygen evolution pattern of wild-type and CrCAH3-less PSII preparations. We showed that CrCAH3 has unique structural features that allow this enzyme to maximize PSII activity at low pH and CO2 concentration.

  20. The underlying cellular mechanism in the effect of tetramethylpyrazine on the anion secretion of colonic mucosa.

    PubMed

    Zhao, Wen-Chao; Duan, Dong-Xiao; Wang, Zhi-Ju; Tang, Ning; Yan, Ming; Zhang, Gui-Hong; Xing, Ying

    2005-12-01

    The present study investigated the underlying cellular mechanism in the effect of ligustrazine (tetramethylpyrazine, TMP) on the anion secretion of colonic mucosa in rats using a short-circuit current (I(sc)) technique in conjunction with "tool drugs." (i) After a pretreatment of the tissues by bathing the bilateral surface with Cl(-)-free Krebs-Henseleit (K-H) solution for over an hour, a basolateral application of 1 mmol/l TMP produced an increase in I(sc), and the total charges transported for 30 min were about 8.7 +/- 1.4 mC/cm(2); an apical pretreatment of DPC and a basolateral addition of acetazolamide decreased the TMP-induced I(sc) by about 60% (P < 0.01) and 45% (P < 0.05), respectively; a basolateral application of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), the inhibitor of Na(+)-HCO(3)(-) cotransporter (NBC), did not alter the TMP-induced I(sc). (ii) After the bilateral surface of mucosa was bathed with HCO(3)(-)-free K-H solution for over an hour, a basolateral application of 1 mmol/l TMP produced an increase in I(sc), and the total charges transported in 30 min were about 8.3 +/- 1.9 mC/cm(2); an apical pretreatment of DPC (1 mmol/l), the inhibitor of Cl(-) channels, decreased the TMP-induced Isc by about 84% (P < 0.01). The basolateral presence of bumetanide (0.1 mmol/l), the inhibitor of Na(+)-K(+)-Cl(-) cotransporter (NKCC), significantly reduced the TMP-evoked I(sc) by about 86% (P < 0.01). In conclusion, (i) ligustrazine could promote colonic mucosa secretion Cl(-) via apical Cl(-) channels and basolateral NKCC; (ii) ligustrazine could promote colonic mucosa secretion HCO(3)(-) via apical Cl(-) channels and the basolateral diffusion of CO(2).

  1. Analysis of hyposmolarity-induced taurine efflux pathways in the bullfrog sympathetic ganglia.

    PubMed

    Sakai, S; Tosaka, T

    1999-03-01

    Hyposmolarity-induced taurine release was dependent on the decrease in medium osmolarity (5-50%) in the satellite glial cells of the bullfrog sympathetic ganglia. Release of GABA induced by hyposmolarity was much less than that of taurine. Omission of external Cl- replaced with gluconate totally suppressed taurine release, but only slightly suppressed GABA release. Bumetanide and furosemide, blockers of the Na+/K+/2Cl- cotransport system, inhibited taurine release by about 40%. Removal of external Na+ by replacement with choline, or omission of K+, suppressed taurine release by 40%. Antagonists of the Cl-/HCO3 exchange system, SITS, DIDS and niflumic acid, significantly reduced taurine release. The carbonic anhydrase inhibitor, acetazolamide, reduced the taurine release by 34%. Omission of external HCO3 by replacement with HEPES caused a 40% increase in the hyposmolarity-induced taurine release. Hyposmolarity-induced GABA release was not affected by bumetanide or SITS. Chloride channel blockers, 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and N-phenylanthranilic acid (DPC), practically abolished taurine release. Blockers of K+ channels, clofilium and quinidine, had no effect on the taurine release. The hyposmolarity-induced taurine release was considerably enhanced by a simultaneous increase in external K+. GABA was not mediated by the same transport pathway as that of taurine. These results indicate that Cl- channels may be responsible for the hyposmolarity-induced taurine release, and that Na+/K+/2Cl- cotransporter and Cl-/HCO3 exchanger may contribute to maintain the intracellular Cl- levels higher than those predicted for a passive thermodynamic distribution in the hyposmolarity-induced taurine release.

  2. Carbonic anhydrase activity in Arabidopsis thaliana thylakoid membrane and fragments enriched with PSI or PSII.

    PubMed

    Ignatova, Lyudmila K; Rudenko, Natalia N; Mudrik, Vilen A; Fedorchuk, Tat'yana P; Ivanov, Boris N

    2011-12-01

    The procedure of isolating the thylakoids and the thylakoid membrane fragments enriched with either photosystem I or photosystem II (PSI- and PSII-membranes) from Arabidopsis thaliana leaves was developed. It differed from the one used with pea and spinach in durations of detergent treatment and centrifugation, and in concentrations of detergent and Mg(2+) in the media. Both the thylakoid and the fragments preserved carbonic anhydrase (CA) activities. Using nondenaturing electrophoresis followed by detection of CA activity in the gel stained with bromo thymol blue, one low molecular mass carrier of CA activity was found in the PSI-membranes, and two carriers, a low molecular mass one and a high molecular mass one, were found in the PSII-membranes. The proteins in the PSII-membranes differed in their sensitivity to acetazolamide (AA), a specific CA inhibitor. AA at 5 × 10(-7) M inhibited the CA activity of the high molecular mass protein but stimulated the activity of the low molecular mass carrier in the PSII-membranes. At the same concentration, AA moderately inhibited, by 30%, the CA activity of PSI-membranes. CA activity of the PSII-membranes was almost completely suppressed by the lipophilic CA inhibitor, ethoxyzolamide at 10(-9) M, whereas CA activity of the PSI-membranes was inhibited by this inhibitor even at 5 × 10(-7) M just the same as for AA. The observed distribution of CA activity in the thylakoid membranes from A. thaliana was close to the one found in the membranes of pea, evidencing the general pattern of CA activity in the thylakoid membranes of C3-plants.

  3. Studies of the electrical potential difference in rat proximal tubule.

    PubMed

    Seely, J F; Chirito, E

    1975-07-01

    The electrical potential difference (PD) in the rat proximal convoluted tubule was investigated in vivo as a function of distance from the glomerulus. The PD was found to be invariably negative (up to -4.5 mV) in the earliest segments (less than 0.5 mm from the glomerulus) and rose to positive values (+2 to +4) in the later segments (1 mm beyond the glomerulus). This change in PD correlated with the bubule fluid-to-plasma (TF/P) chloride ratios, which rose from unity in the early segments to approximately 1.3 in the late. Corresponding changes in PD and chloride ratios could be elicited by single-nephron stop-flow techniques in the early segments. Luminal perfusion techniques demonstrated a direct relationship between PD and tubule fluid chloride concentration. Acetazolamide was found to significantly reduce both late proximal PD (less than +2 mV) and TF/P chloride ratios (less than 1.06). Split-drop studies demonstrated that the negative PD in the early proximal tubule was dependent on the presence of glucose and alanine and the absence of a chloride gradient, whereas in the late proximal tubule under the same conditions the PD was not significantly different from zero. In this segment of the nephron the positive PD in free flow appeared to result from the chloride diffusion potential generated by preferential HCO3 reabsorption. These results provide further demonstration of intrinsic differences in the transport properties along the length of the proximal convoluted tubule.

  4. Continuous positive airway pressure treatment for acute mountain sickness at 4240 m in the Nepal Himalaya.

    PubMed

    Johnson, Pamela L; Johnson, Claire C; Poudyal, Prasanta; Regmi, Nirajan; Walmsley, Megan A; Basnyat, Buddha

    2013-09-01

    Acute mountain sickness (AMS) is very common at altitudes above 2500 m. There are few treatment options in the field where electricity availability is limited, and medical assistance or oxygen is unavailable or difficult to access. Positive airway pressure has been used to treat AMS at 3800 m. We hypothesized that continuous positive airway pressure (CPAP) could be used under field conditions powered by small rechargeable batteries. Methods Part 1. 5 subjects trekked to 3500 m from 2800 m in one day and slept there for one night, ascending in the late afternoon to 3840 m, where they slept using CPAP 6-7 cm via mask. The next morning they descended to 3500 m, spent the day there, ascended in late afternoon to 3840 m, and slept the night without CPAP. Continuous overnight oximetry was recorded and the Lake Louise questionnaire for AMS administered both mornings. Methods Part 2. 14 trekkers with symptoms of AMS were recruited at 4240 m. All took acetazolamide. The Lake Louise questionnaire was administered, oximetry recorded, and CPAP 6-7 cm was applied for 10-15 min. CPAP was used overnight and oximetry recorded continuously. In the morning the Lake Louise questionnaire was administered, and oximetry recorded for 10-15 min. The equipment used in both parts was heated, humidified Respironics RemStar® machines powered by Novuscell™ rechargeable lithium ion batteries. Oximetry was recorded using Embletta™ PDS. Results Part 1. CPAP improved overnight Sao2 and eliminated AMS symptoms in the one subject who developed AMS. CPAP was used for 7-9 h and the machines operated for >8 h using the battery. Results Part 2. CPAP use improved Sao2 when used for 10-15 min at the time of recruitment and overnight CPAP use resulted in significantly reduced AMS symptoms. Conclusion. CPAP with rechargeable battery may be a useful treatment option for trekkers and climbers who develop AMS.

  5. Electrogenic bicarbonate secretion by prairie dog gallbladder.

    PubMed

    Moser, A James; Gangopadhyay, A; Bradbury, N A; Peters, K W; Frizzell, R A; Bridges, R J

    2007-06-01

    Pathological rates of gallbladder salt and water transport may promote the formation of cholesterol gallstones. Because prairie dogs are widely used as a model of this event, we characterized gallbladder ion transport in animals fed control chow by using electrophysiology, ion substitution, pharmacology, isotopic fluxes, impedance analysis, and molecular biology. In contrast to the electroneutral properties of rabbit and Necturus gallbladders, prairie dog gallbladders generated significant short-circuit current (I(sc); 171 +/- 21 microA/cm(2)) and lumen-negative potential difference (-10.1 +/- 1.2 mV) under basal conditions. Unidirectional radioisotopic fluxes demonstrated electroneutral NaCl absorption, whereas the residual net ion flux corresponded to I(sc). In response to 2 microM forskolin, I(sc) exceeded 270 microA/cm(2), and impedance estimates of the apical membrane resistance decreased from 200 Omega.cm(2) to 13 Omega.cm(2). The forskolin-induced I(sc) was dependent on extracellular HCO(3)(-) and was blocked by serosal 4,4'-dinitrostilben-2,2'-disulfonic acid (DNDS) and acetazolamide, whereas serosal bumetanide and Cl(-) ion substitution had little effect. Serosal trans-6-cyano-4-(N-ethylsulfonyl-N-methylamino)-3-hydroxy-2,2-dimethyl-chroman and Ba(2+) reduced I(sc), consistent with the inhibition of cAMP-dependent K(+) channels. Immunoprecipitation and confocal microscopy localized cystic fibrosis transmembrane conductance regulator protein (CFTR) to the apical membrane and subapical vesicles. Consistent with serosal DNDS sensitivity, pancreatic sodium-bicarbonate cotransporter protein pNBC1 expression was localized to the basolateral membrane. We conclude that prairie dog gallbladders secrete bicarbonate through cAMP-dependent apical CFTR anion channels. Basolateral HCO(3)(-) entry is mediated by DNDS-sensitive pNBC1, and the driving force for apical anion secretion is provided by K(+) channel activation.

  6. cAMP stimulates bicarbonate secretion across normal, but not cystic fibrosis airway epithelia.

    PubMed Central

    Smith, J J; Welsh, M J

    1992-01-01

    Adenosine 3',5'-cyclic monophosphate stimulates chloride (Cl-) secretion across airway epithelia. To determine whether cAMP also stimulates HCO3- secretion, we studied cultured canine and human airway epithelial cells bathed in a HCO3-/CO2-buffered, Cl(-)-free solution. Addition of forskolin stimulated an increase in short-circuit current that was likely a result of bicarbonate secretion because it was inhibited by a HCO3(-)-free solution, by addition of the carbonic anhydrase inhibitor, acetazolamide, or by mucosal addition of the anion channel blocker, diphenylamine 2-carboxylate. The current was dependent on Na+ because it was inhibited by removal of Na+ from the submucosal bathing solution, by addition of the Na+ pump inhibitor, ouabain, or by addition of amiloride (1 mM) to the submucosal solution. An increase in cytosolic Ca2+ produced by addition of a Ca2+ ionophore also stimulated short-circuit current. These data suggest that cAMP and Ca2+ stimulate HCO3- secretion across airway epithelium, and suggest that HCO3- leaves the cell across the apical membrane via conductive pathways. These results may explain previous observations that the short-circuit current across airway epithelia was not entirely accounted for by the sum of Na+ absorption and Cl- secretion. The cAMP-induced secretory response was absent in cystic fibrosis (CF) airway epithelial cells, although Ca(2+)-stimulated secretion was intact. This result suggests that HCO3- exist at the apical membrane is through the Cl- channel that is defectively regulated in CF epithelia. These results suggest the possibility that a defect in HCO3- secretion may contribute to the pathophysiology of CF pulmonary disease. PMID:1313448

  7. Inhibition of carbonic anhydrase II by thioxolone: a mechanistic and structural study.

    PubMed

    Barrese, Albert A; Genis, Caroli; Fisher, S Zoe; Orwenyo, Jared N; Kumara, Mudalige Thilak; Dutta, Subodh K; Phillips, Eric; Kiddle, James J; Tu, Chingkuang; Silverman, David N; Govindasamy, Lakshmanan; Agbandje-McKenna, Mavis; McKenna, Robert; Tripp, Brian C

    2008-03-11

    This paper examines the functional mechanism of thioxolone, a compound recently identified as a weak inhibitor of human carbonic anhydrase II by Iyer et al. (2006) J. Biomol. Screening 11, 782-791 . Thioxolone lacks sulfonamide, sulfamate, or hydroxamate functional groups that are typically found in therapeutic carbonic anhydrase (CA) inhibitors, such as acetazolamide. Analytical chemistry and biochemical methods were used to investigate the fate of thioxolone upon binding to CA II, including Michaelis-Menten kinetics of 4-nitrophenyl acetate esterase cleavage, liquid chromatography-mass spectrometry (LC-MS), oxygen-18 isotope exchange studies, and X-ray crystallography. Thioxolone is proposed to be a prodrug inhibitor that is cleaved via a CA II zinc-hydroxide mechanism known to catalyze the hydrolysis of esters. When thioxolone binds in the active site of CA II, it is cleaved and forms 4-mercaptobenzene-1,3-diol via the intermediate S-(2,4-thiophenyl)hydrogen thiocarbonate. The esterase cleavage product binds to the zinc active site via the thiol group and is therefore the active CA inhibitor, while the intermediate is located at the rim of the active-site cavity. The time-dependence of this inhibition reaction was investigated in detail. Because this type of prodrug inhibitor mechanism depends on cleavage of ester bonds, this class of inhibitors may have advantages over sulfonamides in determining isozyme specificity. A preliminary structure-activity relationship study with a series of structural analogues of thioxolone yielded similar estimates of inhibition constants for most compounds, although two compounds with bromine groups at the C1 carbon of thioxolone were not inhibitory, suggesting a possible steric effect.

  8. Episodic ataxia type 2 manifests as epileptiform electroencephalographic activity with no epileptic attacks in two family members.

    PubMed

    Kaido, Misako; Furuta, Mitsuru; Nakamori, Masayuki; Yuasa, Yoshihito; Takahashi, Masanori P

    2016-04-28

    Here, we report two cases of episodic ataxia type 2 (EA2) in a 63-year-old woman and her 36-year-old daughter. The mother experienced recurrent attacks of cerebellar dysfunction lasting 4 to 5 hours since the age of 41 years. On several occasions, she was admitted to the emergency room, where she was diagnosed with epilepsy or stroke. Based on these diagnoses, she was treated with antiepileptic or anticoagulant drugs, but both treatments were eventually discontinued. The frequency of the attacks increased after the patient reached the age of 62. Interictal neurological examination demonstrated signs of slight cerebellar ataxia, i.e. saccadic eye movements, gaze-directed nystagmus, and mild truncal ataxia. Brain magnetic resonance imaging (MRI) showed cerebellar vermis atrophy. Electroencephalography (EEG) revealed various spike and wave patterns: solitary spikes, spike-and-slow wave complexes, and slow wave bursts. Photoparoxysmal response (PPR) type 3 was also observed. Treatment with acetazolamide abolished the patient's attacks almost completely. The daughter started experiencing 5- to 10-minute ataxic episodes at the age of 16 years. Based on her epileptiform EEG activities with PPR (type 2), antiepileptic drugs (valproate and zonisamide) were prescribed. Despite pharmacological treatment, the attacks recurred; however, their frequency gradually decreased with time, until they almost entirely disappeared when the patient was 33. Unfortunately, migraine-like headaches arose instead. Subtle truncal ataxia was observed during interictal periods. Sanger sequencing of the exons of the CACNA1A gene revealed a novel single base deletion (c.3575delA) in both patients. Despite the difference in age of onset and clinical course, both patients showed clearly epileptiform EEG activities without experiencing the concurrent epileptic episodes. Thus, EA2 is a disease that may be misdiagnosed as epilepsy or stroke in the field of emergency medicine.

  9. A novel method to study cerebrospinal fluid dynamics in rats

    PubMed Central

    Karimy, Jason K.; Kahle, Kristopher T.; Kurland, David B.; Yu, Edward; Gerzanich, Volodymyr; Simard, J. Marc

    2014-01-01

    Background Cerebrospinal fluid (CSF) flow dynamics play critical roles in both the immature and adult brain, with implications for neurodevelopment and disease processes such as hydrocephalus and neurodegeneration. Remarkably, the only reported method to date for measuring CSF formation in laboratory rats is the indirect tracer dilution method (a.k.a., ventriculocisternal perfusion), which has limitations. New Method Anesthetized rats were mounted in a stereotaxic apparatus, both lateral ventricles were cannulated, and the Sylvian aqueduct was occluded. Fluid exited one ventricle at a rate equal to the rate of CSF formation plus the rate of infusion (if any) into the contralateral ventricle. Pharmacological agents infused at a constant known rate into the contralateral ventricle were tested for their effect on CSF formation in real-time. Results The measured rate of CSF formation was increased by blockade of the Sylvian aqueduct but was not changed by increasing the outflow pressure (0–3 cm of H2O). In male Wistar rats, CSF formation was age-dependent: 0.39±0.06, 0.74±0.05, 1.02±0.04 and 1.40±0.06 µL/min at 8, 9, 10 and 12 weeks, respectively. CSF formation was reduced 57% by intraventricular infusion of the carbonic anhydrase inhibitor, acetazolamide. Comparison with existing methods Tracer dilution methods do not permit ongoing real-time determination of the rate of CSF formation, are not readily amenable to pharmacological manipulations, and require critical assumptions. Direct measurement of CSF formation overcomes these limitations. Conclusions Direct measurement of CSF formation in rats is feasible. Our method should prove useful for studying CSF dynamics in normal physiology and disease models. PMID:25554415

  10. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

    PubMed Central

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

  11. Crystal structure of the catalytic domain of the tumor-associated human carbonic anhydrase IX.

    PubMed

    Alterio, Vincenzo; Hilvo, Mika; Di Fiore, Anna; Supuran, Claudiu T; Pan, Peiwen; Parkkila, Seppo; Scaloni, Andrea; Pastorek, Jaromir; Pastorekova, Silvia; Pedone, Carlo; Scozzafava, Andrea; Monti, Simona Maria; De Simone, Giuseppina

    2009-09-22

    Carbonic anhydrase (CA) IX is a plasma membrane-associated member of the alpha-CA enzyme family, which is involved in solid tumor acidification. It is a marker of tumor hypoxia and a prognostic factor in several human cancers. An aberrant increase in CA IX expression in chronic hypoxia and during development of various carcinomas contributes to tumorigenesis through at least two mechanisms: pH regulation and cell adhesion control. Here we report the X-ray structure of the catalytic domain of CA IX in complex with a classical, clinically used sulfonamide inhibitor, acetazolamide. The structure reveals a typical alpha-CA fold, which significantly differs from the other CA isozymes when the protein quaternary structure is considered. Thus, two catalytic domains of CA IX associate to form a dimer, which is stabilized by the formation of an intermolecular disulfide bond. The active site clefts and the PG domains are located on one face of the dimer, while the C-termini are located on the opposite face to facilitate protein anchoring to the cell membrane. A correlation between the three-dimensional structure and the physiological role of the enzyme is here suggested, based on the measurement of the pH profile of the catalytic activity for the physiological reaction, CO(2) hydration to bicarbonate and protons. On the basis of the structural differences observed between CA IX and the other membrane-associated alpha-CAs, further prospects for the rational drug design of isozyme-specific CA inhibitors are proposed, given that inhibition of this enzyme shows antitumor activity both in vitro and in vivo.

  12. Secretion of acid and base equivalents by intact distal airways.

    PubMed

    Inglis, S K; Wilson, S M; Olver, R E

    2003-05-01

    Secretion of HCO(3)(-) by airway submucosal glands is essential for normal liquid and mucus secretion. Because the liquid bathing the airway surface (ASL) is acidic, it has been proposed that the surface epithelium may acidify HCO(3)(-)-rich glandular fluid. The aim of this study was to investigate the mechanisms by which intact distal bronchi, which contain both surface and glandular epithelium, modify pH of luminal fluid. Distal bronchi were isolated from pig lungs, cannulated in a bath containing HCO(3)(-)-buffered solution, and perfused continually with an aliquot of similar, lightly buffered solution (LBS) in which NaCl replaced NaHCO(3)(-) (pH 7 with NaOH). The pH of this circulating LBS initially acidified (by 0.053 +/- 0.0053 pH units) and transepithelial potential difference (PD) depolarized. The magnitude of acidification was increased when pH(LBS) was higher. This acidification was unaffected by luminal dimethylamiloride (DMA, 100 microM) but was inhibited by 100 nM bafilomycin A(1) (by 76 +/- 13%), suggesting involvement of vacuolar-H(+) ATPase. Addition of ACh (10 microM) evoked alkalinization of luminal LBS and hyperpolarization of transepithelial PD. The alkalinization was inhibited in HCO(3)(-)-free solutions containing acetazolamide (1 mM) and by DMA and was enhanced by bumetanide (100 microM), an inhibitor of Cl(-) secretion. The hyperpolarization was unaffected by these maneuvers. The anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoate (300 microM) and combined treatment with DMA and bumetanide blocked both the alkalinization and hyperpolarization responses to ACh. These results are consistent with earlier studies showing that ACh evokes glandular secretion of HCO(3)(-) and Cl(-). Isolated distal airways thus secrete both acid and base equivalents.

  13. Ocean acidification alleviates low-temperature effects on growth and photosynthesis of the red alga Neosiphonia harveyi (Rhodophyta).

    PubMed

    Olischläger, Mark; Wiencke, Christian

    2013-12-01

    This study aimed to examine interactive effects between ocean acidification and temperature on the photosynthetic and growth performance of Neosiphonia harveyi. N. harveyi was cultivated at 10 and 17.5 °C at present (~380 µatm), expected future (~800 µatm), and high (~1500 µatm) pCO2. Chlorophyll a fluorescence, net photosynthesis, and growth were measured. The state of the carbon-concentrating mechanism (CCM) was examined by pH-drift experiments (with algae cultivated at 10 °C only) using ethoxyzolamide, an inhibitor of external and internal carbonic anhydrases (exCA and intCA, respectively). Furthermore, the inhibitory effect of acetazolamide (an inhibitor of exCA) and Tris (an inhibitor of the acidification of the diffusive boundary layer) on net photosynthesis was measured at both temperatures. Temperature affected photosynthesis (in terms of photosynthetic efficiency, light saturation point, and net photosynthesis) and growth at present pCO2, but these effects decreased with increasing pCO2. The relevance of the CCM decreased at 10 °C. A pCO2 effect on the CCM could only be shown if intCA and exCA were inhibited. The experiments demonstrate for the first time interactions between ocean acidification and temperature on the performance of a non-calcifying macroalga and show that the effects of low temperature on photosynthesis can be alleviated by increasing pCO2. The findings indicate that the carbon acquisition mediated by exCA and acidification of the diffusive boundary layer decrease at low temperatures but are not affected by the cultivation level of pCO2, whereas the activity of intCA is affected by pCO2. Ecologically, the findings suggest that ocean acidification might affect the biogeographical distribution of N. harveyi.

  14. Selective pharmacological modulation of renal peripheral-type benzodiazepine binding by treatment with diuretic drugs

    SciTech Connect

    Lukeman, D.S.; Vaughn, D.A.; Fanestil, D.D.

    1988-01-01

    The authors have assessed the effects of in vivo administration of different classes of diuretic drugs on the expression of the peripheral-type benzodiazepine binding site (PBBS) in crude membranes derived from the cortex and outer medulla of rat kidney by saturation analysis with the PBBS-selective ligands (/sup 3/H)RO5-4864 and (/sup 3/H)PH 11195 in cortex and (/sup 3/H)RO5-4864 in outer medulla. Administration for 14-15 days of furosemide, a drug that blocks NaCl-KCl coupled transport in the thick ascending limb of the loop of Henle, produced a significant doubling in the PBBS density (B/sub max/) in outer medulla, a region of the kidney rich in thick ascending limbs, and produced a lesser but significant increase in PBBS density in the cortex. Conversely, administration for 14-15 days of the carbonic anhydrase inhibitor acetazolamide, which acts predominantly in the proximal tubule, and hydrochlorothiazide, which acts predominantly in the early distal tubule, elicited statistically significant increases in PBBS density in renal cortex but not in renal outer medulla. Furthermore, all drug treatments were without effect on the equilibrium dissociation constants (K/sub d/s) of (/sup 3/H)RO5-4864 and (/sup 3/H)PK 11195 binding to cortical and outer medullary membrane preparations. These findings demonstrate that the PBBS can be selectively up-regulated in different regions of the kidney by diuretic drugs with different modes/sites of action. 50 references, 1 table.

  15. Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world.

    PubMed

    Burnell, Owen W; Connell, Sean D; Irving, Andrew D; Watling, Jennifer R; Russell, Bayden D

    2014-01-01

    Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3 (-)-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3 (-) acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance.

  16. Tumoral Calcinosis as an Initial Complaint of Juvenile-Onset Amyopathic Dermatomyositis

    PubMed Central

    Doh, Eun Jin; Moon, Jungyoon; Shin, Sue; Seo, Soo Hyun; Park, Hyun Sun; Yoon, Hyun-Sun

    2016-01-01

    Calcinosis is rarely observed in juvenile-onset amyopathic dermatomyositis in contrast to juvenile-onset dermatomyositis. A 6-year-old female presented with several 0.5 to 2 cm-sized painless grouped masses on both knees for 3 years. The patient also presented with multiple erythematous scaly patches and plaques on both elbows, knuckles, buttock, ankles and cheeks. Her mother had similar skin lesions which were erythematous scaly patches on the knuckles and elbows, since her childhood. When skin biopsy was performed from a left knee nodule, liquid chalky discharge was observed. The biopsy results were consistent with calcinosis cutis. Other biopsies from erythematous patch of the patient and erythematous patch of her mother showed vacuolization of basal cell layer with inflammatory cell infiltrations. Laboratory findings showed normal range of serum phosphorus (4.5 mg/dl), calcium (9.3 mg/dl), 1,25-dihydroxy-vitamin D (10.8 ng/ml) and parathyroid hormone levels (11 pg/ml). Both patient and her mother had no history of muscle weakness and showed normal levels of muscle-specific enzyme. Both patients were diagnosed with juvenile-onset amyopathic dermatomyositis based on histopathology and cutaneous manifestations with no evidence of muscle weakness and no serum muscle enzyme abnormalities. Tumoral calcium deposits observed in daughter was diagnosed as dystrophic calcinosis which can be rarely seen in juvenile-onset amyopathic dermatomyositis. The patient is being treated with oral acetazolamide (40 mg/kg/d) for calcinosis. PMID:27274638

  17. Color-Coded Digital Subtraction Angiography in the Management of a Rare Case of Middle Cerebral Artery Pure Arterial Malformation

    PubMed Central

    Feliciano, Caleb E; Pamias-Portalatin, Eva; Mendoza-Torres, Jorge; Effio, Euclides; Moran, Yadira; Rodriguez-Mercado, Rafael

    2014-01-01

    Summary The advent of flow dynamics and the recent availability of perfusion analysis software have provided new diagnostic tools and management possibilities for cerebrovascular patients. To this end, we provide an example of the use of color-coded angiography and its application in a rare case of a patient with a pure middle cerebral artery (MCA) malformation. A 42-year-old male chronic smoker was evaluated in the emergency room due to sudden onset of severe headache, nausea, vomiting and left-sided weakness. Head computed tomography revealed a right basal ganglia hemorrhage. Cerebral digital subtraction angiography (DSA) showed a right middle cerebral artery malformation consisting of convoluted and ectatic collateral vessels supplying the distal middle cerebral artery territory-M1 proximally occluded. An associated medial lenticulostriate artery aneurysm was found. Brain single-photon emission computed tomography with and without acetazolamide failed to show problems in vascular reserve that would indicate the need for flow augmentation. Twelve months after discharge, the patient recovered from the left-sided weakness and did not present any similar events. A follow-up DSA and perfusion study using color-coded perfusion analysis showed perforator aneurysm resolution and adequate, albeit delayed perfusion in the involved vascular territory. We propose a combined congenital and acquired mechanism involving M1 occlusion with secondary dysplastic changes in collateral supply to the distal MCA territory. Angiographic and cerebral perfusion work-up was used to exclude the need for flow augmentation. Nevertheless, the natural course of this lesion remains unclear and long-term follow-up is warranted. PMID:25496681

  18. Inhibition of the β-carbonic anhydrase from Streptococcus pneumoniae by inorganic anions and small molecules: Toward innovative drug design of antiinfectives?

    PubMed

    Burghout, Peter; Vullo, Daniela; Scozzafava, Andrea; Hermans, Peter W M; Supuran, Claudiu T

    2011-01-01

    The Gram-positive bacterium Streptococcus pneumoniae is a human respiratory tract pathogen that contributes significantly to global mortality and morbidity. It was recently shown that this bacterial pathogen depends on a conserved β-carbonic anhydrase (CA, EC 4.2.1.1) for in vitro growth in environmental ambient air and during intracellular survival in host cells. Hence, it is to be expected that this pneumococcal carbonic anhydrase (PCA) contributes to transmission and pathogenesis of the bacterium, making it a potential therapeutic target. In this study, purified recombinant PCA has been further characterized kinetically and for inhibition with a series of inorganic anions and small molecules useful as leads. PCA has appreciable activity as catalyst for the hydration of CO(2) to bicarbonate, with a k(cat) of 7.4×10(5)s(-1) and k(cat)/K(m) of 6.5×10(7) M(-1)s(-1) at an optimum pH of 8.4. Inorganic anions such as chloride, bromide, iodide, cyanate, selenocyanate, trithiocarbonate, and cyanide were effective inhibitors of PCA (K(I)s of 21-98μM). Sulfamide, sulfamic acid, phenylboronic, phenylarsonic acid, and diethyldithiocarbamate showed inhibition constants in the low micromolar/submicromolar range (K(I)s of 0.61-6.68μM), whereas that of the sulfonamide acetazolamide was in the nanomolar range (K(I)s 89nM). In conclusion, our results show that PCA can effectively be inhibited by a range of molecules that could be interesting leads for obtaining more potent PCA inhibitors. PCA might be a novel target for designing antimicrobial drugs with a new mechanism of action.

  19. Carbonic anhydrase II binds to and increases the activity of the epithelial sodium-proton exchanger, NHE3

    PubMed Central

    Krishnan, Devishree; Liu, Lei; Wiebe, Shane A.; Casey, Joseph R.; Cordat, Emmanuelle; Alexander, R. Todd

    2016-01-01

    Two-thirds of sodium filtered by the renal glomerulus is reabsorbed from the proximal tubule via a sodium/proton exchanger isoform 3 (NHE3)-dependent mechanism. Since sodium and bicarbonate reabsorption are coupled, we postulated that the molecules involved in their reabsorption [NHE3 and carbonic anhydrase II (CAII)] might physically and functionally interact. Consistent with this, CAII and NHE3 were closely associated in a renal proximal tubular cell culture model as revealed by a proximity ligation assay. Direct physical interaction was confirmed in solid-phase binding assays with immobilized CAII and C-terminal NHE3 glutathione-S-transferase fusion constructs. To assess the effect of CAII on NHE3 function, we expressed NHE3 in a proximal tubule cell line and measured NHE3 activity as the rate of intracellular pH recovery, following an acid load. NHE3-expressing cells had a significantly greater rate of intracellular pH recovery than controls. Inhibition of endogenous CAII activity with acetazolamide significantly decreased NHE3 activity, indicating that CAII activates NHE3. To ascertain whether CAII binding per se activates NHE3, we expressed NHE3 with wild-type CAII, a catalytically inactive CAII mutant (CAII-V143Y), or a mutant unable to bind other transporters (CAII-HEX). NHE3 activity increased upon wild-type CAII coexpression, but not in the presence of the CAII V143Y or HEX mutant. Together these studies support an association between CAII and NHE3 that alters the transporter’s activity. PMID:26041446

  20. Decrease of intracellular pH as possible mechanism of embryotoxicity of glycol ether alkoxyacetic acid metabolites

    SciTech Connect

    Louisse, Jochem; Verwei, Miriam; Sandt, Johannes J.M. van de; Rietjens, Ivonne M.C.M.

    2010-06-01

    Embryotoxicity of glycol ethers is caused by their alkoxyacetic acid metabolites, but the mechanism underlying the embryotoxicity of these acid metabolites is so far not known. The present study investigates a possible mechanism underlying the embryotoxicity of glycol ether alkoxyacetic acid metabolites using the methoxyacetic acid (MAA) metabolite of ethylene glycol monomethyl ether as the model compound. The results obtained demonstrate an MAA-induced decrease of the intracellular pH (pH{sub i}) of embryonic BALB/c-3T3 cells as well as of embryonic stem (ES)-D3 cells, at concentrations that affect ES-D3 cell differentiation. These results suggest a mechanism for MAA-mediated embryotoxicity similar to the mechanism of embryotoxicity of the drugs valproic acid and acetazolamide (ACZ), known to decrease the pH{sub i}in vivo, and therefore used as positive controls. The embryotoxic alkoxyacetic acid metabolites ethoxyacetic acid, butoxyacetic acid and phenoxyacetic acid also caused an intracellular acidification of BALB/c-3T3 cells at concentrations that are known to inhibit ES-D3 cell differentiation. Two other embryotoxic compounds, all-trans-retinoic acid and 5-fluorouracil, did not decrease the pH{sub i} of embryonic cells at concentrations that affect ES-D3 cell differentiation, pointing at a different mechanism of embryotoxicity of these compounds. MAA and ACZ induced a concentration-dependent inhibition of ES-D3 cell differentiation, which was enhanced by amiloride, an inhibitor of the Na{sup +}/H{sup +}-antiporter, corroborating an important role of the pH{sub i} in the embryotoxic mechanism of both compounds. Together, the results presented indicate that a decrease of the pH{sub i} may be the mechanism of embryotoxicity of the alkoxyacetic acid metabolites of the glycol ethers.

  1. Biochemical characterization of the native α-carbonic anhydrase purified from the mantle of the Mediterranean mussel, Mytilus galloprovincialis.

    PubMed

    Perfetto, Rosa; Del Prete, Sonia; Vullo, Daniela; Sansone, Giovanni; Barone, Carmela; Rossi, Mosè; Supuran, Claudiu T; Capasso, Clemente

    2017-12-01

    A α-carbonic anhydrase (CA, EC 4.2.1.1) has been purified and characterized biochemically from the mollusk Mytilus galloprovincialis. As in most mollusks, this α-CA is involved in the biomineralization processes leading to the precipitation of calcium carbonate in the mussel shell. The new enzyme had a molecular weight of 50 kDa, which is roughly two times higher than that of a monomeric α-class enzyme. Thus, Mytilus galloprovincialis α-CA is either a dimer, or similar to the Tridacna gigas CA described earlier, may have two different CA domains in its polypeptide chain. The Mytilus galloprovincialis α-CA sequence contained the three His residues acting as zinc ligands and the gate-keeper residues present in all α-CAs (Glu106-Thr199), but had a Lys in position 64 and not a His as proton shuttling residue, being thus similar to the human isoform hCA III. This probably explains the relatively low catalytic activity of Mytilus galloprovincialis α-CA, with the following kinetic parameters for the CO2 hydration reaction: kcat = 4.1 × 10(5) s(-1) and kcat/Km of 3.6 × 10(7) M(-1) × s(-1). The enzyme activity was poorly inhibited by the sulfonamide acetazolamide, with a KI of 380 nM. This study is one of the few describing in detail the biochemical characterization of a molluskan CA and may be useful for understanding in detail the phylogeny of these enzymes, their role in biocalcification processes and their potential use in the biomimetic capture of the CO2.

  2. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    PubMed

    Ow, Yan X; Uthicke, Sven; Collier, Catherine J

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

  3. Treatment of Epilepsy

    PubMed Central

    Bailey, Allan A.

    1963-01-01

    The main clinical types of epilepsy and their treatment are described. The treatment of choice in petit mal epilepsy is trimethadione (Trimedone) 0.3 g., three to six times a day, or acetazolamide (Diamox) 125-250 mg., three to four times a day. Phenobarbital is usually given as well to prevent grand mal seizures. Diphenylhydantoin sodium (Dilantin Sodium), 100 mg., and/or phenobarbital, 30-100 mg., three to four times a day, is recommended in patients with focal and grand mal epilepsy. Psychomotor automatisms are a form of focal seizure. Primidone (Mysoline), in doses of 125-250 mg. two to three times a day, is a very useful anticonvulsant in patients with myoclonic features, psychomotor automatisms and grand mal seizures. Primidone should be started in small doses. Drug reactions, especially cerebellar ataxia in the case of diphenylhydantoin and blood dyscrasias in the case of some drugs, should be recognized. Excessive drowsiness can be avoided by proper dosage and proper timing of drug administration. Patients should be seen regularly at least two to three times a year. The objective of treatment is to achieve optimum control of seizures by using the appropriate drug in adequate dosage. Social adaptation is good in the majority of patients, who should be encouraged to carry on their life independently, usually free to marry and have children. Attention to special occupational hazards has to be considered. Education of employers and employees is often necessary. Special work arrangements are occasionally indicated for selected patients. Patients should be seizure-free for two to three years before permission is given to drive an automobile. PMID:13969008

  4. Mutations in the Na+/Citrate Cotransporter NaCT (SLC13A5) in Pediatric Patients with Epilepsy and Developmental Delay

    PubMed Central

    Klotz, Jenna; Porter, Brenda E; Colas, Claire; Schlessinger, Avner; Pajor, Ana M

    2016-01-01

    Mutations in the SLC13A5 gene that codes for the Na+/citrate cotransporter, NaCT, are associated with early onset epilepsy, developmental delay and tooth dysplasia in children. In this study, we identify additional SLC13A5 mutations in nine epilepsy patients from six families. To better characterize the syndrome, families with affected children answered questions about the scope of illness and the treatment strategies. Currently, there are no effective treatments, but some antiepileptic drugs targeting the γ-aminobutyric acid system reduce seizure frequency. Acetazolamide, a carbonic anhydrase inhibitor and atypical antiseizure medication, decreases seizures in four patients. In contrast to previous reports, the ketogenic diet and fasting resulted in worsening of symptoms. The effects of the mutations on NaCT transport function and protein expression were examined by transient transfections of COS-7 cells. There was no transport activity from any of the mutant transporters, although some of the mutant transporter proteins were present on the plasma membrane. The structural model of NaCT suggests that these mutations can affect helix packing or substrate binding. We tested various treatments, including chemical chaperones and low temperatures, but none improved transport function in the NaCT mutants. Interestingly, coexpression of NaCT and the mutants results in decreased protein expression and activity of the wild-type transporter, indicating functional interaction. In conclusion, this study has identified additional SLC13A5 mutations in patients with chronic epilepsy starting in the neonatal period, with the mutations producing inactive Na+/citrate transporters. PMID:27261973

  5. Topiramate modulates pH of hippocampal CA3 neurons by combined effects on carbonic anhydrase and Cl-/HCO3- exchange.

    PubMed

    Leniger, Tobias; Thöne, Jan; Wiemann, Martin

    2004-07-01

    Topiramate (TPM) is an anticonvulsant whose impact on firing activity and intracellular pH (pHi) regulation of CA3 neurons was investigated. Using the 4-aminopyridine-treated hippocampal slice model bathed in bicarbonate-buffered solution, TPM (25-50 microm) reduced the frequency of epileptiform bursts and action potentials without affecting membrane potential or input resistance. Inhibitory effects of TPM were reversed by trimethylamine-induced alkalinization. TPM also lowered the steady-state pHi of BCECF-AM-loaded neuronal somata by 0.18+/-0.07 pH units in CO(2)/HCO(3)(-)-buffered solution. Subsequent to an ammonium prepulse, TPM reduced the acidotic peak but clearly slowed pHi recovery. These complex changes were mimicked by the protein phosphatase inhibitor okadaic acid. Alkalosis upon withdrawal of extracellular Cl(-) was augmented by TPM. Furthermore, at decreased pHi due to the absence of extracellular Na(+), TPM reversibly increased pHi. These findings demonstrate that TPM modulates Na(+)-independent Cl(-)/HCO(3)(-) exchange. In the nominal absence of extracellular CO(2)/HCO(3)(-) buffer, both steady-state pHi and firing of epileptiform bursts remained unchanged upon adding TPM. However, pHi recovery subsequent to an ammonium prepulse was slightly increased, as was the case in the presence of the carbonic anhydrase (CA) inhibitor acetazolamide. Thus, a slight reduction of intracellular buffer capacity by TPM may be due to an inhibitory effect on intracellular CA. Together, these findings show that TPM lowers neuronal pHi most likely due to a combined effect on Na(+)-independent Cl(-)/HCO(3)(-) exchange and CA. The apparent decrease of steady-state pHi may contribute to the anticonvulsive property of TPM.

  6. Bicarbonate-dependent chloride transport drives fluid secretion by the human airway epithelial cell line Calu-3

    PubMed Central

    Shan, Jiajie; Liao, Jie; Huang, Junwei; Robert, Renaud; Palmer, Melissa L; Fahrenkrug, Scott C; O'Grady, Scott M; Hanrahan, John W

    2012-01-01

    Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl− and HCO3− secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)-deficient and CFTR-expressing cell lines derived from the human airway epithelial cell line Calu-3. Forskolin stimulated the short-circuit current (Isc) across voltage-clamped monolayers, and also increased the equivalent short-circuit current (Ieq) calculated under open-circuit conditions. Isc was equivalent to the HCO3− net flux measured using the pH-stat technique, whereas Ieq was the sum of the Cl− and HCO3− net fluxes. Ieq and HCO3− fluxes were increased by bafilomycin and ZnCl2, suggesting that some secreted HCO3− is neutralized by parallel electrogenic H+ secretion. Ieq and fluid secretion were dependent on the presence of both Na+ and HCO3−. The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of Ieq and HCO3− secretion, suggesting that HCO3− transport under these conditions requires catalysed synthesis of carbonic acid. Cl− was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50–70% of Cl− and fluid transport was bumetanide-insensitive, suggesting basolateral Cl− loading by a sodium–potassium–chloride cotransporter 1 (NKCC1)-independent mechanism. Imposing a transepithelial HCO3− gradient across basolaterally permeabilized Calu-3 cells sustained a forskolin-stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR-deficient cells. Net HCO3− secretion was increased by bilateral Cl− removal and therefore did not require apical Cl−/HCO3− exchange. The results suggest a model in which most HCO3− is recycled basolaterally by exchange with Cl−, and the resulting HCO3−-dependent Cl− transport provides an osmotic driving force for

  7. In vivo support for the new concept of pulmonary blood flow-mediated CO2 gas excretion in the lungs.

    PubMed

    Kawai, Yoshiko; Ajima, Kumiko; Kaidoh, Maki; Sakaguchi, Masao; Tanaka, Satoshi; Kawamata, Mikito; Kimura, Hiroko; Ohhashi, Toshio

    2015-06-15

    To further examine the validity of the proposed concept of pulmonary blood flow-dependent CO2 gas excretion in the lungs, we investigated the effects of intramediastinal balloon catheterization-, pulmonary artery catheterization-, or isoprenaline (ISP)-induced changes in pulmonary blood flow on the end-expiratory CO2 gas pressure (PeCO2 ), the maximal velocity of the pulmonary artery (Max Vp), systemic arterial pressure, and heart rate of anesthetized rabbits. We also evaluated the changes in the PeCO2 in clinical models of anemia or pulmonary embolism. An almost linear relationship was detected between the PeCO2 and Max Vp. In an experiment in which small pulmonary arteries were subjected to stenosis, the PeCO2 fell rapidly, and the speed of the reduction was dependent on the degree of stenosis. ISP produced significant increases in the PeCO2 of the anesthetized rabbits. Conversely, treatment with piceatannol or acetazolamide induced significant reductions in the PeCO2 . Treatment with a cell surface F1/FO ATP synthase antibody caused significant reductions in the PeCO2 itself and the ISP-induced increase in the PeCO2 . Neither the PeCO2 nor SAP was significantly influenced by marked anemia [%hematocrit (Ht), 70 ∼ 47%]. On the other hand, in the presence of less severe anemia (%Ht: 100 ∼ 70%) both the PeCO2 and SAP fell significantly when the rabbits' blood viscosity was decreased. The rabbits in which pulmonary embolisms were induced demonstrated significantly reduced PeCO2 values, which was compatible with the lowering of their Max Vp. In conclusion, we reaffirm the validity of the proposed concept of CO2 gas exchange in the lungs.

  8. Effect of genistein on basal jejunal chloride secretion in R117H CF mice is sex and route specific

    PubMed Central

    Rayyan, Esa; Polito, Sarah; Leung, Lana; Bhakta, Ashesh; Kang, Jonathan; Willey, Justin; Mansour, Wasim; Drumm, Mitchell L; Al-Nakkash, Layla

    2015-01-01

    Cystic fibrosis (CF) results from the loss or reduction in function of the CFTR (cystic fibrosis transmembrane conductance regulatory protein) chloride channel. The third most common CFTR mutation seen clinically is R117H. Genistein, a naturally occurring phytoestrogen, is known to stimulate CFTR function in vitro. We aimed to determine whether route of administration of genistein could mediate differential effects in R117H male and female CF mice. Mice were fed (4 weeks) or injected subcutaneously (1 week) with the following: genistein 600 mg/kg diet (600Gd); genistein-free diet (0Gd); genistein injection 600 mg/kg body weight (600Gi); dimethyl sulfoxide control (0Gi). In male R117H mice fed 600Gd, basal short circuit current (Isc) was unchanged. In 600Gd-fed female mice, there was a subgroup that demonstrated a significant increase in basal Isc (53.14±7.92 μA/cm2, n=6, P<0.05) and a subgroup of nonresponders (12.05±6.59 μA/cm2, n=4), compared to 0Gd controls (29.3±6.5 μA/cm2, n=7). In R117H mice injected with 600Gi, basal Isc was unchanged in both male and female mice compared to 0Gi controls. Isc was measured in response to the following: the adenylate cyclase activator forskolin (10 μM, bilateral), bumetanide (100 μM, basolateral) to indicate the Cl− secretory component, and acetazolamide (100 μM, bilateral) to indicate the HCO3− secretory component; however, there was no effect of genistein (diet or injection) on any of these parameters. Jejunal morphology (ie, villi length, number of goblet cells per villus, crypt depth, and number of goblet cells per crypt) in R117H mice suggested no genistein-mediated difference among the groups. Serum levels of genistein were significantly elevated, compared to respective controls, by either 600Gd (equally elevated in males and females) or 600Gi (elevated more in females versus males). These data suggest a sex-dependent increase in basal Isc of R117H mice and that the increase is also specific for route of

  9. A Novel Stopped-Flow Assay for Quantitating Carbonic-Anhydrase Activity and Assessing Red-Blood-Cell Hemolysis

    PubMed Central

    Zhao, Pan; Geyer, R. Ryan; Boron, Walter F.

    2017-01-01

    We report a novel carbonic-anhydrase (CA) assay and its use for quantitating red-blood-cell (RBC) lysis during stopped-flow (SF) experiments. We combine two saline solutions, one containing HEPES/pH 7.03 and the other, ~1% CO2/44 mM HCO3-/pH 8.41, to generate an out-of-equilibrium CO2/HCO3- solution containing ~0.5% CO2/22 HCO3-/pH ~7.25 (10°C) in the SF reaction cell. CA catalyzes relaxation of extracellular pH to ~7.50: HCO3- + H+ → CO2 + H2O. Proof-of-concept studies (no intact RBCs) show that the pH-relaxation rate constant (kΔpH)—measured via pyranine fluorescence—rises linearly with increases in [bovine CAII] or [murine-RBC lysate]. The y-intercept (no CA) was kΔpH = 0.0183 s−1. Combining increasing amounts of murine-RBC lysate with ostensibly intact RBCs (pre-SF hemolysis ≅0.4%)—fixing total [hemoglobin] at 2.5 μM in the reaction cell to simulate hemolysis from ostensibly 0 to 100%—causes kΔpH to increase linearly. This y-intercept (0% lysate/100% ostensibly intact RBCs) was kΔpH = 0.0820 s−1, and the maximal kΔpH (100% lysate/0% intact RBCs) was 1.304 s−1. Thus, mean percent hemolysis in the reaction cell was ~4.9%. Phenol-red absorbance assays yield indistinguishable results. The increase from 0.4 to 4.9% presumably reflects mechanical RBC disruption during rapid mixing. In all fluorescence studies, the CA blocker acetazolamide reduces kΔpH to near-uncatalyzed values, implying that all CA activity is extracellular. Our lysis assay is simple, sensitive, and precise, and will be valuable for correcting for effects of lysis in physiological SF experiments. The underlying CA assay, applied to blood plasma, tissue-culture media, and organ perfusates could assess lysis in a variety of applications.

  10. Cerebellar Ataxia.

    PubMed

    Perlman

    2000-05-01

    There is nothing more discouraging than for a patient to be given a specific diagnosis, then to be told that there is nothing that can be done. Physicians are equally disheartened to see exponential progress being made in the understanding of the pathophysiology of a complex disorder but few direct benefits resulting for their patients. Over the past 5 years, molecular genetic research has completely revolutionized the way in which the progressive cerebellar ataxias are classified and diagnosed, but it has yet to produce effective gene-based, neuroprotective, or neurorestorative therapies. The treatment of cerebellar ataxia remains primarily a neurorehabilitation challenge, employing physical, occupational, speech, and swallowing therapy; adaptive equipment; driver safety training; and nutritional counseling. Modest additional gains are seen with the use of medications that can improve imbalance, incoordination, or dysarthria (amantadine, buspirone, acetazolamide); cerebellar tremor (clonazepam, propranolol); and cerebellar or central vestibular nystagmus (gabapentin, baclofen, clonazepam). Many of the progressive cerebellar syndromes have associated features involving other neurologic systems (eg, spasticity, dystonia or rigidity, resting or rubral tremor, chorea, motor unit weakness or fatigue, autonomic dysfunction, peripheral or posterior column sensory loss, neuropathic pain or cramping, double vision, vision and hearing loss, dementia, and bowel, bladder, and sexual dysfunction), which can impede the treatment of the ataxic symptoms or can worsen with the use of certain drugs. Treatment of the associated features themselves may in turn worsen the ataxia either directly (as side effects of medication) or indirectly (eg, relaxation of lower limb spasticity that was acting as a stabilizer for an ataxic gait). Secondary complications of progressive ataxia can include deconditioning or immobility, weight loss or gain, skin breakdown, recurrent pulmonary and

  11. Risk assessment of physiological effects of atmospheric composition and pressure in Constellation vehicles

    NASA Astrophysics Data System (ADS)

    Scheuring, Richard; Conkin, Johnny; Jones, Jeffrey A.; Gernhardt, Michael L.

    CEV, and use a gradual or staged reduction in cabin pressure during lunar outbound; (2) train crews for symptoms of hypoxia, to allow early recognition and consider pre-adaptation of crews to a hypoxic environment prior to launch; (3) consider prophylactic acetazolamide for acute pressure changes and be prepared to treat any AMS associated symptoms early with both carbonic anhydrase inhibitors and supplemental oxygen.

  12. Adaptive appetites for salted and unsalted food in rats: differential effects of sodium depletion, DOCA, and dehydration.

    PubMed

    McKinley, M J

    2013-06-15

    Most ingested sodium is contained in food. The aim was to investigate whether sodium depletion, dehydration, or DOCA alters intakes of salted and unsalted foods by rats given choices of two foods: salted (0.2-0.5% Na) and unsalted food containing either similar or different other dietary components. Diuretic-induced (furosemide or acetazolamide, two treatments on successive days) sodium depletion always caused pronounced falls in intake of unsalted food within 24 h, continuing at least another 2 days (e.g., 20.9 ± 1.6 pretreatment to 14.8 ± 1.2, 10.6 ± 1.5, and 14.3 ± 1.3 g/day for 3 days of depletion). Intake and preference for salted food increased after 24-72 h (e.g., 6.5 ± 1.2 pretreatment to 7.1 ± 1.1, 16.4 ± 2.3, and 17.0 ± 1.5 g/day at 1, 2, and 3 days of depletion). Valsartan (10 mg/day) blocked the increased intake of salted food but not the reduced intake of unsalted food. DOCA (2 mg/day) caused equivalent increase and decrease in intakes of salted and unsalted food, respectively. Water-deprived rats reduced intake (e.g., 14.2 ± 3.1 to 3.2 ± 2.0 g/day) of and preference for salted food (e.g., 56 ± 13% to 21 ± 11%) after 2 days of dehydration but did not consistently reduce intake of unsalted food. Total food ingested/day fell in both sodium-depleted and dehydrated rats. Rats regulate intakes of different foods to balance sodium needs, osmoregulatory homeostasis, and energy requirements. Reduced appetite for unsalted food may be a homeostatic response to sodium depletion, which together with subsequent generation of appetite for salted food, drives animals to ingest sodium-containing food, thereby restoring sodium balance.

  13. Treatment of typical absence seizures and related epileptic syndromes.

    PubMed

    Panayiotopoulos, C P

    2001-01-01

    diagnose and treat. Valproic acid, ethosuximide and lamotrigine, alone or in combination, are first-line therapy. Valproic acid controls absences in 75% of patients and also GTCS (70%) and myoclonic jerks (75%); however, it may be undesirable for some women. Similarly, lamotrigine may control absences and GTCS in possibly 50 to 60% of patients, but may worsen myoclonic jerks; skin rashes are common. Ethosuximide controls 70% of absences, but it is unsuitable as monotherapy if other generalised seizures coexist. A combination of any of these 3 drugs may be needed for resistant cases. Low dosages of lamotrigine added to valproic acid may have a dramatic beneficial effect. Clonazepam, particularly in absences with myoclonic components, and acetazolamide may be useful adjunctive drugs.

  14. Biotic Control of Surface pH and Evidence of Light-Induced H+ Pumping and Ca2+-H+ Exchange in a Tropical Crustose Coralline Alga

    PubMed Central

    Hofmann, Laurie C.; Koch, Marguerite; de Beer, Dirk

    2016-01-01

    Presently, an incomplete mechanistic understanding of tropical reef macroalgae photosynthesis and calcification restricts predictions of how these important autotrophs will respond to global change. Therefore, we investigated the mechanistic link between inorganic carbon uptake pathways, photosynthesis and calcification in a tropical crustose coralline alga (CCA) using microsensors. We measured pH, oxygen (O2), and calcium (Ca2+) dynamics and fluxes at the thallus surface under ambient (8.1) and low (7.8) seawater pH (pHSW) and across a range of irradiances. Acetazolamide (AZ) was used to inhibit extracellular carbonic anhydrase (CAext), which mediates hydrolysis of HCO3-, and 4,4′ diisothiocyanatostilbene-2,2′-disulphonate (DIDS) that blocks direct HCO3- uptake by anion exchange transport. Both inhibited photosynthesis, suggesting both diffusive uptake of CO2 via HCO3- hydrolysis to CO2 and direct HCO3- ion transport are important in this CCA. Surface pH was raised approximately 0.3 units at saturating irradiance, but less when CAext was inhibited. Surface pH was lower at pHSW 7.8 than pHSW 8.1 in the dark, but not in the light. The Ca2+ fluxes were large, complex and temporally variable, but revealed net Ca2+ uptake under all conditions. The temporal variability in Ca2+ dynamics was potentially related to localized dissolution during epithallial cell sloughing, a strategy of CCA to remove epiphytes. Simultaneous Ca2+ and pH dynamics suggest the presence of Ca2+/H+ exchange. Rapid light-induced H+ surface dynamics that continued after inhibition of photosynthesis revealed the presence of a light-mediated, but photosynthesis-independent, proton pump. Thus, the study indicates metabolic control of surface pH can occur in CCA through photosynthesis and light-inducible H+ pumps. Our results suggest that complex light-induced ion pumps play an important role in biological processes related to inorganic carbon uptake and calcification in CCA. PMID:27459463

  15. High-speed gas chromatography in doping control: fast-GC and fast-GC/MS determination of beta-adrenoceptor ligands and diuretics.

    PubMed

    Brunelli, Claudio; Bicchi, Carlo; Di Stilo, Antonella; Salomone, Alberto; Vincenti, Marco

    2006-12-01

    In official doping controls, about 300 drugs and metabolites have to be screened for each sample. Moreover, the number of determinations to be routinely processed increases continuously as the number of both samples and potential illicit drugs keeps growing. As a consequence, increasingly specific, sensitive, and, above all, fast methods for doping controls are needed. The present study presents an efficient fast-GC/MS approach to the routine screening of two different classes of doping agents, namely beta-adrenoceptor ligands and diuretics (belonging to the S3, P2, and S5 groups of the WADA list of prohibited substances). Narrow bore columns (100 mm id) of different lengths and coated with apolar stationary phases were successfully used to separate the derivatized analytes; preliminary experiments (results not shown) showed better performances with OV-1701 for the separation of beta-adrenoceptor ligands. On the same stationary phase some diuretics required too high a temperature or a long isothermal time for elution, in which case a DB1-MS column was preferred. Two methods of sample preparation, derivatization, and analysis were used on aqueous standard mixtures of, respectively, (i) eight beta-adrenoceptor ligands, including five beta-antagonists (acebutolol, alprenolol, atenolol, metoprolol, pindolol) and three beta2-agonists (salbutamol, clenbuterol, terbutaline) and (ii) seventeen diuretic drugs (acetazolamide, althiazide, bendroflumethiazide, bumethanide, canrenone, chlorothiazide, chlortalidone, clopamide, ethacrinic acid, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, indomethacine, spironolactone, triamterene, trichloromethiazide) and one masking agent (probenecid). The mixture of beta-adrenoceptor ligand derivatives was efficiently separated in about 5.6 min, while the one of 18 diuretics and masking agents required less than 5 min for analysis. Limits of detection were from 1 microg/L for pindolol, ethacrinic acid, furosemide

  16. XModeScore: a novel method for accurate protonation/tautomer-state determination using quantum-mechanically driven macromolecular X-ray crystallographic refinement

    PubMed Central

    Borbulevych, Oleg; Martin, Roger I.; Tickle, Ian J.; Westerhoff, Lance M.

    2016-01-01

    Gaining an understanding of the protein–ligand complex structure along with the proper protonation and explicit solvent effects can be important in obtaining meaningful results in structure-guided drug discovery and structure-based drug discovery. Unfortunately, protonation and tautomerism are difficult to establish with conventional methods because of difficulties in the experimental detection of H atoms owing to the well known limitations of X-ray crystallography. In the present work, it is demonstrated that semiempirical, quantum-mechanics-based macromolecular crystallographic refinement is sensitive to the choice of a protonation-state/tautomer form of ligands and residues, and can therefore be used to explore potential states. A novel scoring method, called XModeScore, is described which enumerates the possible protomeric/tautomeric modes, refines each mode against X-ray diffraction data with the semiempirical quantum-mechanics (PM6) Hamiltonian and scores each mode using a combination of energetic strain (or ligand strain) and rigorous statistical analysis of the difference electron-density distribution. It is shown that using XModeScore it is possible to consistently distinguish the correct bound protomeric/tautomeric modes based on routine X-ray data, even at lower resolutions of around 3 Å. These X-ray results are compared with the results obtained from much more expensive and laborious neutron diffraction studies for three different examples: tautomerism in the acetazolamide ligand of human carbonic anhydrase II (PDB entries 3hs4 and 4k0s), tautomerism in the 8HX ligand of urate oxidase (PDB entries 4n9s and 4n9m) and the protonation states of the catalytic aspartic acid found within the active site of an aspartic protease (PDB entry 2jjj). In each case, XModeScore applied to the X-ray diffraction data is able to determine the correct protonation state as defined by the neutron diffraction data. The impact of QM-based refinement versus conventional

  17. S0859, an N-cyanosulphonamide inhibitor of sodium-bicarbonate cotransport in the heart

    PubMed Central

    Ch'En, F F-T; Villafuerte, F C; Swietach, P; Cobden, P M; Vaughan-Jones, R D

    2008-01-01

    Background and purpose: Intracellular pH (pHi) in heart is regulated by sarcolemmal H+-equivalent transporters such as Na+-H+ exchange (NHE) and Na+-HCO3 − cotransport (NBC). Inhibition of NBC influences pHi and can be cardioprotective in animal models of post-ischaemic reperfusion. Apart from a rabbit polyclonal NBC-antibody, a selective NBC inhibitor compound has not been studied. Compound S0859 (C29H24ClN3O3S) is a putative NBC inhibitor. Here, we provide the drug's chemical structure, test its potency and selectivity in ventricular cells and assess its suitability for experiments on cardiac contraction. Experimental approach: pHi recovery from intracellular acidosis was monitored using pH-epifluorescence (SNARF-fluorophore) in guinea pig, rat and rabbit isolated ventricular myocytes. Electrically evoked cell shortening (contraction) was measured optically. With CO2/HCO3 −-buffered superfusates containing 30 μM cariporide (to inhibit NHE), pHi recovery is mediated by NBC. Key results: S0859, an N-cyanosulphonamide compound, reversibly inhibited NBC-mediated pHi recovery (K i=1.7 μM, full inhibition at ∼30 μM). In HEPES-buffered superfusates, NHE-mediated pHi recovery was unaffected by 30 μM S0859. With CO2/HCO3 − buffer, pHi recovery from intracellular alkalosis (mediated by Cl−/HCO3 − and Cl−/OH− exchange) was also unaffected. Selective NBC-inhibition was not due to action on carbonic anhydrase (CA) enzymes, as 100 μM acetazolamide (a membrane-permeant CA-inhibitor) had no significant effect on NBC activity. pHi recovery from acidosis was associated with increased contractile-amplitude. The time course of recovery of pHi and contraction was slowed by S0859, confirming that NBC is a significant controller of contractility during acidosis. Conclusions and implications: Compound S0859 is a selective, high-affinity generic NBC inhibitor, potentially important for probing the transporter's functional role in heart and other tissues

  18. Mechanism of exaggerated natriuresis in hypertensive man: impaired sodium transport in the loop of henle

    PubMed Central

    Buckalew, Vardaman M.; Puschett, Jules B.; Kintzel, James E.; Goldberg, Martin

    1969-01-01

    To evaluate the effects of saline loading on distal sodium reabsorption in hypertensive man, studies were performed during both water deprivation and water diuresis in eight hypertensive subjects, and the results were compared to data obtained from similar studies in normal subjects. All hypertensive patients exhibited an enhanced excretion of filtered sodium (CNa/CIn) at any level of distal delivery of sodium compared to normal controls. Free water reabsorption (TcH2O) during hypertonic saline loading was quantitatively abnormal in the hypertensives at high levels of osmolar clearance (COsm), and also the curve of TcH2O vs. COsm leveled off above a COsm of 18 ml/min per 1.73 m2 in the hypertensive group in contrast to the normal controls in whom TcH2O showed no evidence of achieving an upper limit. Sodium depletion exaggerated the abnormality in TcH2O in hypertensives, and resulted in a positive free water clearance (CH2O) during hydropenia. During hypotonic saline loading in water diuresis, changes in free water clearance per 100 ml of glomerular filtrate (CH2O/CIn) were less at any given increment in urine flow per 100 ml of glomerular filtrate (V/CIn) in the hypertensives compared to normal controls (P < 0.001). This abnormality in CH2O/CIn in the hypertensives in conjunction with the defect in TcH2O observed during hydropenia indicates that sodium reabsorption in the loop of Henle was abnormal at any given rate of distal delivery of sodium in hypertension. Furthermore, these abnormalities in TcH2O and CH2O coincided temporally with the development of the exaggerated natriuresis. Although the distal defect in sodium transport, in large part, accounted for the augmented natriuresis in hypertension, evidence was present also for enhanced rejection of sodium in the proximal tubule during saline loading in the hypertensives. Additional studies utilizing acetazolamide which increases distal delivery of sodium without extracellular fluid volume expansion showed only

  19. Mechanisms for vasopressin effects on intraocular pressure in anesthetized rats

    NASA Technical Reports Server (NTRS)

    Balaban, C. D.; Palm, D. E.; Shikher, V.; Searles, R. V.; Keil, L. C.; Severs, W. B.

    1997-01-01

    Continuous intracameral infusions of a balanced salt solution (0.175 microliter min-1) have been reported to raise intraocular pressure (IOP) in anesthetized rats. Palm et al. (1995) previously reported that this effect was attenuated significantly by inclusion of arginine-vasopressin (AVP, 10 ng 0.175 microliter-1) in the infusate. This study used experimental and computer simulation methods to investigate factors underlying these changes in IOP. First, constant intracameral infusions of artificial cerebrospinal fluid (aCSF) at different fixed rates (0.049-0.35 microliter min-1) were used to estimate the outflow resistance. Secondly, IOP responses were measured during an 2 hr intracameral infusion of either aCSF or AVP that was the sum of a small constant component (0.05 microliter min-1) and a larger periodic component (0.25 microliter min-1, cycling for 4 min on, then 4 min off); the mean infusion rate was 0.175 microliter min-1. As shown previously for 0.175 microliter min-1 constant infusions, the periodic aCSF infusion induced a significant rise in IOP that was attenuated by AVP administration. Complex demodulation analysis and the estimated gain parameter of a second order transfer function fit to the periodic responses indicated that outflow resistance increased significantly during the infusions in both aCSF and AVP groups, but that the indices of resistance did not differ significantly between aCSF and AVP infused eyes. This finding implies that changes in outflow resistance do not explain the difference in IOP responses to intracameral aCSF and AVP. The two responses differed significantly, though, in damping factors, such that the aCSF responses were considerably more underdamped than the AVP responses. It is hypothesized that aCSF-induced increase in IOP reflects both (1) a small component reflecting increased outflow resistance and (2) a larger non-resistive component. Since the non-resistive component is insensitive to pretreatment with acetazolamide

  20. XModeScore: a novel method for accurate protonation/tautomer-state determination using quantum-mechanically driven macromolecular X-ray crystallographic refinement.

    PubMed

    Borbulevych, Oleg; Martin, Roger I; Tickle, Ian J; Westerhoff, Lance M

    2016-04-01

    Gaining an understanding of the protein-ligand complex structure along with the proper protonation and explicit solvent effects can be important in obtaining meaningful results in structure-guided drug discovery and structure-based drug discovery. Unfortunately, protonation and tautomerism are difficult to establish with conventional methods because of difficulties in the experimental detection of H atoms owing to the well known limitations of X-ray crystallography. In the present work, it is demonstrated that semiempirical, quantum-mechanics-based macromolecular crystallographic refinement is sensitive to the choice of a protonation-state/tautomer form of ligands and residues, and can therefore be used to explore potential states. A novel scoring method, called XModeScore, is described which enumerates the possible protomeric/tautomeric modes, refines each mode against X-ray diffraction data with the semiempirical quantum-mechanics (PM6) Hamiltonian and scores each mode using a combination of energetic strain (or ligand strain) and rigorous statistical analysis of the difference electron-density distribution. It is shown that using XModeScore it is possible to consistently distinguish the correct bound protomeric/tautomeric modes based on routine X-ray data, even at lower resolutions of around 3 Å. These X-ray results are compared with the results obtained from much more expensive and laborious neutron diffraction studies for three different examples: tautomerism in the acetazolamide ligand of human carbonic anhydrase II (PDB entries 3hs4 and 4k0s), tautomerism in the 8HX ligand of urate oxidase (PDB entries 4n9s and 4n9m) and the protonation states of the catalytic aspartic acid found within the active site of an aspartic protease (PDB entry 2jjj). In each case, XModeScore applied to the X-ray diffraction data is able to determine the correct protonation state as defined by the neutron diffraction data. The impact of QM-based refinement versus conventional

  1. Extracellular pH in the isolated retina of the toad in darkness and during illumination.

    PubMed Central

    Oakley, B; Wen, R

    1989-01-01

    1. Extracellular pH (pHo) was measured in the isolated retina preparation of the toad, Bufo marinus, using H(+)-selective microelectrodes. During superfusion with phosphate-buffered solution (pH 7.8), which had a low buffering capacity, pHo in the inner retina was 7.0-7.2 and there was a pHo gradient throughout the distal retina and into the bathing solution. 2. The retinal acidity appears to be due in part to the combined reactions of glycolysis and ATP hydrolysis, since anoxia greatly increased the pHo gradient, while superfusion with either glucose-free pyruvate solution or strophanthidin decreased this gradient. 3. Maintained illumination evoked both an acidification in the proximal retina and an alkalinization in the distal retina. Blocking synaptic transmission to second-order neurones (1.0 mM-aspartate) decreased the acidification but had little effect on the alkalinization, consistent with the notion that the alkalinization is of receptoral origin, while the acidification is of post-receptoral origin. 4. Retinal neurones extrude a significant amount of acid via Na(+)-H+ exchange, since 2.0 mM-amiloride, a blocker of Na(+)-H+ exchange, caused a sustained alkalinization in darkness and decreased the light-evoked changes in pHo, while 1.0 mM-4-acetamido-4'-isothiocyanatostilbene-2.2'-disulphonic acid (SITS), a blocker of Cl(-)-HCO3- exchange, produced a much smaller alkalinization. 5. Switching to a bicarbonate-buffered solution having a 75 times greater buffering capacity than the phosphate-buffered solution caused retinal pHo to become less acidic and significantly decreased the amplitude of the light-evoked pHo changes. 6. Addition of 2.0 mM-acetazolamide, a carbonic anhydrase inhibitor, to the bicarbonate-buffered solution increased both the pHo gradient and the light-evoked changes in pHo. These data are consistent with the idea that carbonic anhydrase, which is concentrated in Müller (glial) cells and to a lesser extent in horizontal cells, increases

  2. Cyclosporin A drug interactions. Screening for inducers and inhibitors of cytochrome P-450 (cyclosporin A oxidase) in primary cultures of human hepatocytes and in liver microsomes.

    PubMed

    Pichard, L; Fabre, I; Fabre, G; Domergue, J; Saint Aubert, B; Mourad, G; Maurel, P

    1990-01-01

    detected as potential competitive inhibitors included: triacetyloleandomycin, erythromycin, josamycin, midecamycin, ketoconazole, miconazole, midazolam, nifedipin, diltiazem, verapamil, nicardipine, ergotamine, dihydroergotamine, glibenclamide, bromocriptine, ethynylestradiol, progesterone, cortisol, prednisone, prednisolone, and methylprednisolone. Finally, cefoperazone, cefotaxime, ceftazidime, isoniazide, doxycycline, spiramycin, sulfamethoxazole, norfloxacin, pefloxacin, vancocin, trimethoprim, amphotericin B, valproic acid, quinidine, cimetidine, ranitidine, omeprazole, diclofenac, aspirin, paracetamol, debrisoquine, guanoxan, captopril, furosemide, acetazolamide, sparteine, gliclazide, and imipramine were found not to interfere with the hepatic metabolism of CsA.

  3. Risk Assessment of Physiological Effects of Atmospheric Composition and Pressure in Constellation Vehicles

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Conkin, Johnny; Jones, J. A.; Gernhardt, M.

    2007-01-01

    = 77 mmHg). So the following may be employed for operational risk reduction: 1) develop procedures to increase PB as needed in the CEV, and use a gradual or staged reduction in cabin pressure during lunar outbound; 2) train crews for symptoms of hypoxia, to allow early recognition and consider pre-adaptation of crews to a hypoxic environment prior to launch, 3) consider prophylactic acetazolamide for acute pressure changes and be prepared to treat any AMS associated symptoms early with both carbonic anhydrase inhibitors and supplemental oxygen.

  4. Risk Assessment of Physiological Effects of Atmospheric Composition and Pressure in Constellation Vehicles

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Conkin, Johnny; Jones, Jeffrey A.; Gernhardt, Michael L.

    2007-01-01

    environment. Conclusions: We feel that the slightly elevated risk of AMS with the recommended exploration atmospheric parameters is offset by the DCS risk reduction and improved operational efficiency offered by the hypobaric lunar surface vehicular pressure. We believe the risk of mild AMS is greater given a (P(sub A)O2) of 77 mmHg at 4,876 m altitude while breathing 32% O2 than at 1,828 m altitude while breathing 21% O2. Only susceptible astronauts would develop mild and transient AMS with prolonged exposure to 414 mmHg (4,876 m) while breathing 32% O2 (acute (P(sub A)O2) = 77 mmHg). So the following may be employed for operational risk reduction: 1) develop procedures to increase P(sub B) as needed in the CEV, and use a gradual or staged reduction in cabin pressure during lunar outbound; 2) train crews for symptoms of hypoxia, to allow early recognition and consider pre-adaptation of crews to a hypoxic environment prior to launch, 3) consider prophylactic acetazolamide for acute pressure changes and be prepared to treat any AMS associated symptoms early with both carbonic anhydrase inhibitors and supplemental oxygen.

  5. Quantification of carbonate by gas chromatography-mass spectrometry.

    PubMed

    Tsikas, Dimitrios; Chobanyan-Jürgens, Kristine

    2010-10-01

    -MS in the NICI mode by selected ion monitoring of the anions [M-H](-) of CH(3)COCH=C(OPFB)(2) at m/z 461 for the endogenous species and m/z 462 for the internal standard (13)CO(3)(2-). Oral intake of the carboanhydrase inhibitor drug acetazolamide by two healthy volunteers resulted in temporary increased excretion of tCO(2) in the urine. The method is specific for carbonate, accurate, sensitive and should be applicable to various matrices including human fluids and environmental samples.

  6. Second-messenger regulation of sodium transport in mammalian airway epithelia.

    PubMed Central

    Graham, A; Steel, D M; Alton, E W; Geddes, D M

    1992-01-01

    1. Sodium absorption is the dominant ion transport process in conducting airways and is a major factor regulating the composition of airway surface liquid. However, little is known about the control of airway sodium transport by intracellular regulatory pathways. 2. In sheep tracheae and human bronchi mounted in Ussing chambers under short circuit conditions, the sodium current can be isolated by pretreating tissues with acetazolamide (100 microM) to inhibit bicarbonate secretion, bumetanide (100 microM) to inhibit chloride secretion and phloridzin (200 microM) to inhibit sodium-glucose cotransport. This sodium current consists of amiloride-sensitive (57%) and amiloride-insensitive (43%) components. 3. The regulation of the isolated sodium current by three second messenger pathways was studied using the calcium ionophore A23187 to elevate intracellular calcium, a combination of forskolin and the phosphodiesterase inhibitor zardaverine to elevate intracellular cyclic AMP, and the phorbol ester 12,13-phorbol dibutyrate (PDB) to stimulate protein kinase C. 4. In sheep trachea, A23187 produces a dose-related inhibition of the sodium current with maximal effect (38% of ISC) at 10 microM and IC50 1 microM. This response affects both the amiloride-sensitive and insensitive components of the sodium current and is not altered by prior stimulation of protein kinase C or elevation of intracellular cyclic AMP. In human bronchi, A23187 (10 microM) produced a significantly greater inhibition of ISC (68%), a response which was unaffected by prior treatment with PDB or forskolin-zardaverine. 5. In sheep trachea, stimulation of protein kinase C with PDB produced a dose-related inhibition of ISC maximal (56% of ISC) at 50 nM (IC50 7 nM). This response was abolished by amiloride (100 microM) pretreatment suggesting a selective effect on the amiloride-sensitive component of the sodium current. The response was not altered by prior elevation of intracellular calcium or cyclic AMP. PDB

  7. Human eccrine sweat gland epithelial cultures express ductal characteristics.

    PubMed Central

    Brayden, D J; Cuthbert, A W; Lee, C M

    1988-01-01

    1. Isolated human eccrine sweat glands were cultured in vitro. Cells were harvested and plated onto permeable supports to form confluent cell sheets, area 0.2 cm2. These were used to study the electrogenic transepithelial transport of ions by measurement of short-circuit current (SCC). Epithelial sheets had a basal SCC of 5.89 +/- 0.62 microA cm-2 (n = 33) and a transepithelial resistance of 74.1 +/- 5.6 omega cm2 (n = 33). The transepithelial potential difference varied between -0.2 and -1.8 mV with a mean value of -0.71 +/- 0.09 mV (n = 33). 2. The basal current was abolished by addition of 10 microM-amiloride to the apical bathing solution. The concentration of amiloride which inhibited basal SCC by 50% (EC50) was 0.4 microM. Cultures prepared from the secretory coil of sweat glands, rather than from whole glands, were similarly sensitive to amiloride (EC50 = 0.8 microM). 3. Lysylbradykinin (LBK), carbachol, isoprenaline, prostaglandin E2 (PGE2) and A23187 all increased SCC in cultures from whole glands. LBK responses were obtained with basolateral and not with apical application. Furthermore LBK actions were not substantially altered by cyclo-oxygenase inhibition but showed marked desensitization upon repeated application. Sheet cultures prepared from sweat gland coils also showed SCC responses to both carbachol and LBK. Forskolin, an activator of adenylate cyclase, did not alter SCC in either type of preparation. 4. Replacement of chloride and of chloride and bicarbonate in the bathing solution did not cause attenuation of the responses to LBK or carbachol in whole-gland sheet cultures. Furthermore responses were unaffected by piretanide or acetazolamide. These results were taken to indicate that anion secretion was not the basis for the SCC responses. 5. Responses to LBK and carbachol were significantly reduced by amiloride (10 microM), this effect being reversible. No responses to LBK or carbachol were seen when N-methyl-D-glucamine (NMDG) was used to

  8. Intracellular pH and its regulation in isolated type I carotid body cells of the neonatal rat.

    PubMed Central

    Buckler, K J; Vaughan-Jones, R D; Peers, C; Nye, P C

    1991-01-01

    1. The dual-emission pH-sensitive fluoroprobe carboxy-SNARF-1 (carboxy-seminaptharhodofluor) was used to measure pHi in type I cells enzymically dispersed from the neonatal rat carotid body. 2. Steady-state pHi in cells bathed in a HEPES-buffered Tyrode solution (pH 7.4) was found to be remarkably alkaline (pHi = 7.77) whereas cells bathed in a CO2-HCO3(-)-buffered Tyrode solution (pH 7.4) had a more 'normal' pHi (pHi = 7.28). These observations were further substantiated by using an independent nullpoint test method to determine pHi. 3. Intracellular intrinsic buffering (beta, determined by acidifying the cell using an NH4Cl pre-pulse) was in the range 7-20 mM per pH unit and appeared to be dependent upon pHi with beta increasing as pHi decreased. 4. In cells bathed in a HEPES-buffered Tyrode solution, pHi recovery from an induced intracellular acid load (10 mM-NH4Cl pre-pulse) was inhibited by the Na(+)-H+ exchange inhibitor ethyl isopropyl amiloride (EIPA; 150 microM) or substitution of Nao+ with N-methyl-D-glucamine (NMG). Both EIPA and Nao+ removal also caused a rapid intracellular acidification, which in the case of Nao+ removal, was readily reversible. The rate of this acidification was similar for both Nao+ removal and EIPA addition. 5. Transferring cells from a HEPES-buffered Tyrode solution to one buffered with 5% CO2-HCO3- resulted in an intracellular acidification which was partially, or wholly, sustained. The rate of acidification upon transfer to CO2-HCO3- was considerably slowed by the membrane permeant carbonic anhydrase inhibitor, acetazolamide, thus indicating the presence of the enzyme in these cells. 6. In CO2-HCO3(-)-buffered Tyrode solution, pHi recovery from an intracellular acidosis (NH4+ pre-pulse) was only partially inhibited by EIPA or amiloride whereas Nao+ removal completely inhibited the recovery. The stilbene DIDS (4,4-diisothiocyanatostilbenedisulphonic acid, 200 microM) also partially inhibited pHi recovery following an induced

  9. Respiratory medicine at McMaster University, Hamilton, Ontario: 1968 to 2013

    PubMed Central

    Jones, Norman L; O’Byrne, Paul M

    2014-01-01

    disorders. EXERCISE CAPACITY: Norman Jones and Moran Campbell developed a system for noninvasive cardiopulmonary exercise testing using an incremental exercise test, and more complex studies with measurement of mixed venous PCO2 by rebreathing. The 6 min walk test was validated by Gordon Guyatt. Kieran Killian and Norman Jones introduced routine muscle strength measurements in clinical testing and symptom assessment in exercise testing. Muscle strength training improved exercise capacity in older subjects and patients with chronic obstructive pulmonary disease. METABOLISM AND ACID-BASE CONTROL IN EXERCISE: After showing that imposed acidosis reduced, and alkalosis improved performance, Norman Jones, John Sutton and George Heigenhauser investigated the interactions between acid-base status and metabolism in exercise. HIGH-ALTITUDE MEDICINE: John Sutton and Peter Powles participated in high-altitude research on Mount Logan (Yukon), demonstrating sleep hypoxemia in acute mountain sickness and its reversal by acetazol-amide, and participated in Operation Everest II. EPIDEMIOLOGY: David Pengelly and Tony Kerrigan followed children living in areas with differing air quality to show that lung development was adversely affected by pollution and maternal smoking. Malcolm Sears and Neil Johnstone showed that the ‘return to school’ asthma exacerbation epidemic was due mainly to rhinoviruses. David Muir investigated the effects of silica exposure in hard-rock miners, and mortality in the nickel industry. SUMMARY: The Respirology Division has grown to more than 50 physicians and PhD scientists, and currently provides the busiest outpatient clinic in Hamilton, and has successful training and research programs.