Adaptation of the vestibulo-ocular reflex for forward-eyed foveate vision

PubMed Central

Migliaccio, Americo A; Minor, Lloyd B; Santina, Charles C Della

2010-01-01

To maintain visual fixation on a distant target during head rotation, the angular vestibulo-ocular reflex (aVOR) should rotate the eyes at the same speed as the head and in exactly the opposite direction. However, in primates for which the 3-dimensional (3D) aVOR has been extensively characterised (humans and squirrel monkeys (Saimiri sciureus)), the aVOR response to roll head rotation about the naso-occipital axis is lower than that elicited by yaw and pitch, causing errors in aVOR magnitude and direction that vary with the axis of head rotation. In other words, primates keep the central part of the retinal image on the fovea (where photoreceptor density and visual acuity are greatest) but fail to keep that image from twisting about the eyes' resting optic axes. We tested the hypothesis that aVOR direction dependence is an adaptation related to primates' frontal-eyed, foveate status through comparison with the aVOR of a lateral-eyed, afoveate mammal (Chinchilla lanigera). As chinchillas' eyes are afoveate and never align with each other, we predicted that the chinchilla aVOR would be relatively low in gain and isotropic (equal in gain for every head rotation axis). In 11 normal chinchillas, we recorded binocular 3D eye movements in darkness during static tilts, 20–100 deg s−1 whole-body sinusoidal rotations (0.5–15 Hz), and 3000 deg s−2 acceleration steps. Although the chinchilla 3D aVOR gain changed with both frequency and peak velocity over the range we examined, we consistently found that it was more nearly isotropic than the primate aVOR. Our results suggest that primates' anisotropic aVOR represents an adaptation to their forward-eyed, foveate status. In primates, yaw and pitch aVOR must be compensatory to stabilise images on both foveae, whereas roll aVOR can be under-compensatory because the brain tolerates torsion of binocular images that remain on the foveae. In contrast, the lateral-eyed chinchilla faces different adaptive demands and thus enlists a different aVOR strategy. PMID:20724359

Non-invasive endocrine monitoring of ovarian and adrenal activity in chinchilla (Chinchilla lanigera) females during pregnancy, parturition and early post-partum period.

PubMed

Mastromonaco, Gabriela F; Cantarelli, Verónica I; Galeano, María G; Bourguignon, Nadia S; Gilman, Christine; Ponzio, Marina F

2015-03-01

The chinchilla is a rodent that bears one of the finest and most valuable pelts in the world. The wild counterpart is, however, almost extinct because of a drastic past and ongoing population decline. The present work was developed to increase our knowledge of the reproductive physiology of pregnancy and post-partum estrus in the chinchilla, characterizing the endocrine patterns of urinary progesterone, estradiol, LH and cortisol metabolites throughout gestation and post-partum estrus and estimating the ovulation timing at post-partum estrus. Longitudinal urine samples were collected once per week throughout pregnancy and analyzed for creatinine, cortisol, LH, estrogen and progesterone metabolite concentrations. To indirectly determine the ovulation timing at post-partum estrus, a second experiment was performed using pregnant females subjected to a post-partum in vivo fertilization scheme. Urinary progestagen metabolites increased above baseline levels in early pregnancy between weeks-8 and -11 respectively to parturition, and slightly declined at parturition time. Urinary estrogens showed rising levels throughout mid- and late pregnancy (weeks-9 to -6 and a further increase at week-5 to parturition) and decreased in a stepwise manner after parturition, returning to baseline levels two weeks thereafter. Cortisol metabolite levels were relatively constant throughout pregnancy with a tendency for higher levels in the last third of gestation and after the pups' birth. Parturition was associated with dramatic reductions in urinary concentrations of sex steroids (especially progestagens). Observations in breeding farms indicated that the females that resulted in a second pregnancy after mating, did so on the second day after parturition. These data were in agreement with an LH peak detected 24h after parturition. Urinary steroid hormone patterns of estrogen and progestagen metabolites provided valuable information on endocrine events during pregnancy and after parturition in the chinchilla. Results presented in this study enhance our understanding of natural reproductive dynamics in the chinchilla and support empirical observations of breeders that post-partum ovulation occurs ∼ 48 h after parturition. Copyright © 2015 Elsevier Inc. All rights reserved.

Pliocene Paleoenvironments of Southeastern Queensland, Australia Inferred from Stable Isotopes of Marsupial Tooth Enamel

PubMed Central

Montanari, Shaena; Louys, Julien; Price, Gilbert J.

2013-01-01

The Chinchilla Local Fauna is a diverse assemblage of both terrestrial and aquatic Pliocene vertebrates from the fluviatile Chinchilla Sand deposits of southeastern Queensland, Australia. It represents one of Australia's few but exceptionally rich Pliocene vertebrate localities, and as such is an important source of paleoecological data concerning Pliocene environmental changes and its effects on ecosystems. Prior inferences about the paleoenvironment of this locality made on the basis of qualitative observations have ranged from grassland to open woodland to wetland. Examination of the carbon and oxygen isotopes in the tooth enamel of marsupials from this site represents a quantitative method for inferring the paleoenvironments and paleoecology of the fossil fauna. Results from Chinchilla show that Protemnodon sp. indet. consumed both C3 and C4 photosynthesis plant types (mean δ13C = −14.5±2.0‰), and therefore probably occupied a mixed vegetation environment. Macropus sp. indet. from Chinchilla also consumed a mixed diet of both C3 and C4 plants, with more of a tendency for C4 plant consumption (mean δ13C = −10.3±2.3‰). Interestingly, their isotopic dietary signature is more consistent with tropical and temperate kangaroo communities than the sub-tropical communities found around Chinchilla today. Other genera sampled in this study include the extinct kangaroo Troposodon sp. indet. and the fossil diprotodontid Euryzygoma dunense each of which appear to have occupied distinct dietary niches. This study suggests that southeastern Queensland hosted a mosaic of tropical forests, wetlands and grasslands during the Pliocene and was much less arid than previously thought. PMID:23776636

Successful cardiopulmonary resuscitation following cardiopulmonary arrest in a geriatric chinchilla.

PubMed

Fernandez, Christina M; Peyton, Jamie L; Miller, Mona; Johnson, Eric G; Kovacic, Jan P

2013-01-01

To describe the successful application of CPR in a geriatric chinchilla employing basic and advanced life support measures during cardiopulmonary arrest (CPA). A 13-year-old female intact chinchilla presented to a general and multispecialty referral hospital for a dental procedure. During recovery from anesthesia the patient suffered CPA and CPR was initiated. Noninvasive positive pressure mask ventilation was initiated and external chest compressions were performed. An 18-Ga needle was introduced into the medullary cavity of the right humerus as an intraosseous catheter and provided access for administration of drugs and fluids. After return of spontaneous circulation was noted mannitol was administered via the intraosseous catheter to alleviate suspected increased intracranial pressure. Clinical improvement was noted shortly after administration. Monitoring during the recovery period showed a normal sinus cardiac rhythm and a SpO₂ of 100% while on supplemental oxygen. Neurologic function continued to improve over the following hours. Oxygen therapy was provided via an oxygen cage, and administration of antimicirobials, gastrointestinal protectants, and nutritional supplementation were part of the post resuscitation care. Oxygen therapy was discontinued after 24 hours, during which time normal behaviors were observed and neurologic status was considered appropriate. The patient was discharged 48 hours after CPA. Published reports from clinical practice on the outcomes of CPR for exotic small mammals are limited. This report details the successful outcome of the use of combined basic and advanced life support measures for the provision of CPR in a chinchilla. This report also highlights the utility of an intraosseous catheter for administration of drugs and fluids novel to this species during resuscitation and recovery. To the authors' knowledge this is the first published report of successful CPR following CPA in a geriatric chinchilla. © Veterinary Emergency and Critical Care Society 2013.

Structures that Contribute to Middle-Ear Admittance in Chinchilla

PubMed Central

Rosowski, John J.; Ravicz, Michael E.; Songer, Jocelyn E.

2009-01-01

We describe measurements of middle-ear input admittance in chinchillas (Chinchilla lanigera) before and after various manipulations that define the contributions of different middle-ear components to function. The chinchilla’s middle-ear air spaces have a large effect on the low-frequency compliance of the middle ear, and removing the influences of these spaces reveals a highly admittant tympanic membrane and ossicular chain. Measurements of the admittance of the air spaces reveal that the high-degree of segmentation of these spaces has only a small effect on the admittance. Draining the cochlea further increases the middle-ear admittance at low frequencies and removes a low-frequency (less than 300 Hz) level dependence in the admittance. Spontaneous or sound-driven contractions of the middle-ear muscles in deeply anesthetized animals were associated with significant changes in middle-ear admittance. PMID:16944166

Organisation of autonomic nervous structures in the small intestine of chinchilla (Chinchilla laniger, Molina).

PubMed

Nowak, E

2014-08-01

Using histochemical, histological and immunocytochemical methods, organisation of the autonomic nerve structures in small intestine of chinchilla was investigated. Myenteric plexus was localised between circular and longitudinal layers of the smooth muscles. Forming network nodes, the small autonomic, cholinergic ganglia were linked with the bundles of nerve fibres. Adrenergic structures were visible as specific varicose, rosary-like fibres forming bundles of parallel fibres connecting network nodes. Structures of the submucosal plexus formed a finer network than those of the myenteric plexus. Moreover, in 'whole-mount' specimens, fibres forming thick perivascular plexuses were also observed. Immunocytochemical studies confirmed the cholinergic and adrenergic character of the investigated structures. VAChT-positive neurones were found only in myenteric plexus, and numerous VAChT-positive and DBH-positive fibres were found in both plexuses. © 2013 Blackwell Verlag GmbH.

Guinea pig and chinchilla care and husbandry.

PubMed

Donnelly, Thomas M; Brown, Cynthia J

2004-05-01

This article reviews breeds and coat colors of guinea pigs and chinchillas, their husbandry, care and anatomy. The unusual reproductive physiology and reproductive diseases of these animals are described. We cover nutrition, the potential for disease on poor diets, and the vocalization of hystricomorph rodents. Skills such as handling, sexing, blood collection and drug administration, including antibiotic toxicity are described. The conclusion lists recommended textbooks, pet owner manuals, and websites.

Parvovirus-Derived Endogenous Viral Elements in Two South American Rodent Genomes

PubMed Central

2014-01-01

We describe endogenous viral elements (EVEs) derived from parvoviruses (family Parvoviridae) in the genomes of the long-tailed chinchilla (Chinchilla lanigera) and the degu (Octodon degus). The novel EVEs include dependovirus-related elements and representatives of a clearly distinct parvovirus lineage that also has endogenous representatives in marsupial genomes. In the degu, one dependovirus-derived EVE was found to carry an intact reading frame and was differentially expressed in vivo, with increased expression in the liver. PMID:25078696

Selective damage to cochlear efferents by the choline neurotoxin ethylcholine mustard aziridinium ion (AF64A) in the chinchilla.

PubMed

Smith, D W; Mount, R J; Callahan, J W

1989-10-01

The cholinotoxin ethylcholine mustard aziridinium ion (AF64A) was diluted in artificial perilymph to concentrations ranging from 10-100 microM, injected unilaterally into the bulla of chinchillas, and allowed to passively diffuse across the round window membrane. Following 21-day survival, the animals were sacrificed and ears removed and embedded in epoxy for histological evaluation under both light and transmission electron microscopy. At 10 microM concentration, selective degeneration of efferent fibers was observed in the efferent terminals on outer hair cells (OHC), tunnel radial fibers, tunnel spiral bundle, and the inner spiral bundle. Serial sections of the middle turn of an animal at 10 microM concentrations showed normal efferent terminals on approximately 50% of OHCs. At the higher concentrations non-specific damage was seen in OHCs, afferents, and some supporting cells. These data suggest that low doses AF64A produces selective damage to cochlear efferent terminals and fibers in the chinchilla.

A mechano-acoustic model of the effect of superior canal dehiscence on hearing in chinchilla

PubMed Central

Songer, Jocelyn E.; Rosowski, John J.

2008-01-01

Superior canal dehiscence (SCD) is a pathological condition of the ear that can cause a conductive hearing loss. The effect of SCD (a hole in the bony wall of the superior semicircular canal) on chinchilla middle- and inner-ear mechanics is analyzed with a circuit model of the dehiscence. The model is used to predict the effect of dehiscence on auditory sensitivity and mechanics. These predictions are compared to previously published measurements of dehiscence related changes in chinchilla cochlear potential, middle-ear input admittance and stapes velocity. The comparisons show that the model predictions are both qualitatively and quantitatively similar to the physiological results for frequencies where physiologic data are available. The similarity supports the third-window hypothesis of the effect of superior canal dehiscence on auditory sensitivity and mechanics and provides the groundwork for the development of a model that predicts the effect of superior canal dehiscence syndrome on auditory sensitivity and mechanics in humans. PMID:17672643

Parvovirus-derived endogenous viral elements in two South American rodent genomes.

PubMed

Arriagada, Gloria; Gifford, Robert J

2014-10-01

We describe endogenous viral elements (EVEs) derived from parvoviruses (family Parvoviridae) in the genomes of the long-tailed chinchilla (Chinchilla lanigera) and the degu (Octodon degus). The novel EVEs include dependovirus-related elements and representatives of a clearly distinct parvovirus lineage that also has endogenous representatives in marsupial genomes. In the degu, one dependovirus-derived EVE was found to carry an intact reading frame and was differentially expressed in vivo, with increased expression in the liver. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Viability and virulence of pneumolysin, pneumococcal surface protein A, and pneumolysin/pneumococcal surface protein A mutants in the ear.

PubMed

Schachern, Patricia A; Tsuprun, Vladimir; Goetz, Sarah; Cureoglu, Sebahattin; Juhn, Steven K; Briles, David E; Paparella, Michael M; Ferrieri, Patricia

2013-09-01

Understanding how pneumococcal proteins affect the pathology of the middle ear and inner ear is important for the development of new approaches to prevent otitis media and its complications. To determine the viability and virulence of Streptococcus pneumoniae mutants deficient in pneumolysin (Ply-) and pneumococcal surface protein A (PspA-) in the chinchilla middle ear. Bullae of chinchillas were inoculated bilaterally with wild-type (Wt), Ply-, PspA-, and Ply-/PspA- strains. Bacterial colony-forming units (CFUs) in middle ear effusions were counted at 48 hours. The CFUs of the PspA- group were also counted at 6 to 36 hours after inoculation. Temporal bone histopathological results were compared. Twenty-seven chinchillas in an academic research laboratory. Chinchilla middle ears were inoculated with S pneumoniae to produce sufficient volumes of effusions and noticeable histopathological changes in the ears. The CFU counts in the middle ear effusions and histopathological changes were compared to determine the effect of pneumococcal protein mutations on chinchilla ears. At 48 hours, CFUs in middle ears were increased for the Wt and Ply-/PspA- strains, but Ply- remained near inoculum level. No bacteria were detected in the PspA- group. The CFUs of PspA- decreased over time to a low level at 30 to 36 hours. In vitro, PspA- in Todd-Hewitt broth showed an increase in bacterial growth of 2 logs at 43 hours, indicating PspA- susceptibility to host defenses in vivo. The PspA- and Ply- groups had fewer pathologic findings than the Wt or Ply-/PspA- groups. Histopathological analysis showed significant differences in the number of bacteria in the scala tympani in the Wt group compared with the Ply-, PspA-, and Ply-/PspA- groups. The PspA- strain was the least virulent. The PspA- mutant was much less viable and less virulent in the ear than the Wt, Ply-, and Ply-/PspA- strains. There was no significant attenuation in the viability and virulence of the Ply-/PspA- mutant compared with the Wt or single mutants. The viability and virulence of pneumococcal mutants seemed to be protein and organ specific.

Chinchilla laniger can be used as an experimental model for Taenia solium taeniasis.

PubMed

Maravilla, Pablo; Garza-Rodriguez, Adriana; Gomez-Diaz, Benjamin; Jimenez-Gonzalez, Diego Emiliano; Toral-Bastida, Elizabeth; Martinez-Ocaña, Joel; West, Brett; Molina, Nadia; Garcia-Cortes, Ramon; Kawa-Karasik, Simon; Romero-Valdovinos, Mirza; Avila-Ramirez, Guillermina; Flisser, Ana

2011-12-01

Chinchilla laniger has been reported as an experimental definitive host for Taenia solium; however no information about its suitability and yield of gravid tapeworm proglottids containing viable and infective eggs has been published. In total 55 outbred female chinchillas were infected with 4 cysticerci each; hosts were immunodeppressed with 6 or 8 mg of methyl-prednisolone acetate every 14 days starting the day of infection and their discomfort was followed. Kinetics of coproantigen ELISA or expelled proglottids was used to define the infection status. Efficiency of tapeworm establishment was 21% and of parasite gravidity was 8%; chinchillas showed some degree of suffering along the infection. Viability of eggs obtained from gravid proglottids was tested comparing methods previously published, our results showed 62% viability with propidium iodide, 54% with trypan blue, 34% with neutral red, 30% by oncosphere activation and 7% with bromide 3-(4,5-dimetil-tiazol-2-il)-2,5-difenil-tetrazolio (MTT) reduction; no statistical differences were obtained between most techniques, except activation. Four piglets were infected with 50,000 eggs each, necropsy was performed 3 months later and, after counting the number of cysticerci recovered, the percentage of infection was similar to data obtained with T. solium eggs recovered from humans. Our results demonstrate that the experimental model of T. solium taeniasis in C. laniger is a good alternative for providing eggs and adult tapeworms to be used in different types of experiments; optimization of the model probably depends on the use of inbred hosts and on the reduction of infected animals' suffering. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Different virulence of influenza A virus strains and susceptibility to pneumococcal otitis media in chinchillas.

PubMed Central

Giebink, G S; Wright, P F

1983-01-01

We have previously shown that chinchillas infected with a multiply passaged laboratory strain of influenza A/NWS/33 (H1N1) develop negative middle-ear pressure; polymorphonuclear leukocyte oxidative, bactericidal, and chemotactic dysfunction; and increased susceptibility to pneumococcal otitis media. Because influenza A virus strains show different virulence in humans, three such strains were compared in the chinchilla model. Negative middle-ear pressure and tympanic membrane inflammation developed significantly more often in chinchillas infected with wild-type H3N2 virus than with either wild-type H1N1 virus or an attenuated, cold-adapted H3N2 vaccine strain, CR29. Marked depression in polymorphonuclear leukocyte chemiluminescent activity also developed significantly more often in H3N2 infected animals than in H1N1- or CR29-infected animals. Intranasal challenge of influenza virus-infected animals with type 7 Streptococcus pneumoniae resulted in a significantly greater occurrence of pneumococcal otitis media in H3N2-infected animals than in H1N1-, CR29-, or non-influenza-infected control animals. Clearance of pneumococci from nasal washings of animals infected with wild-type H3N2 was significantly delayed in comparison with the other groups. Thus, the previously demonstrated increased susceptibility to otitis media among children infected with H3N2 influenza virus may relate to the capacity of this strain to induce negative middle-ear pressure, polymorphonuclear leukocyte dysfunction, and alteration in the mucosal clearance of pneumococci. PMID:6885170

Human neural tuning estimated from compound action potentials in normal hearing human volunteers

NASA Astrophysics Data System (ADS)

Verschooten, Eric; Desloovere, Christian; Joris, Philip X.

2015-12-01

The sharpness of cochlear frequency tuning in humans is debated. Evoked otoacoustic emissions and psychophysical measurements suggest sharper tuning in humans than in laboratory animals [15], but this is disputed based on comparisons of behavioral and electrophysiological measurements across species [14]. Here we used evoked mass potentials to electrophysiologically quantify tuning (Q10) in humans. We combined a notched noise forward masking paradigm [9] with the recording of trans tympanic compound action potentials (CAP) from masked probe tones in awake human and anesthetized monkey (Macaca mulatta). We compare our results to data obtained with the same paradigm in cat and chinchilla [16], and find that CAP-Q10values in human are ˜1.6x higher than in cat and chinchilla and ˜1.3x higher than in monkey. To estimate frequency tuning of single auditory nerve fibers (ANFs) in humans, we derive conversion functions from ANFs in cat, chinchilla, and monkey and apply these to the human CAP measurements. The data suggest that sharp cochlear tuning is a feature of old-world primates.

Direct evaluation of Pseudomonas aeruginosa biofilm mediators in a chronic infection model.

PubMed

Byrd, Matthew S; Pang, Bing; Hong, Wenzhou; Waligora, Elizabeth A; Juneau, Richard A; Armbruster, Chelsie E; Weimer, Kristen E D; Murrah, Kyle; Mann, Ethan E; Lu, Haiping; Sprinkle, April; Parsek, Matthew R; Kock, Nancy D; Wozniak, Daniel J; Swords, W Edward

2011-08-01

Biofilms contribute to Pseudomonas aeruginosa persistence in a variety of diseases, including cystic fibrosis, burn wounds, and chronic suppurative otitis media. However, few studies have directly addressed P. aeruginosa biofilms in vivo. We used a chinchilla model of otitis media, which has previously been used to study persistent Streptococcus pneumoniae and Haemophilus influenzae infections, to show that structures formed in vivo are biofilms of bacterial and host origin within a matrix that includes Psl, a P. aeruginosa biofilm polysaccharide. We evaluated three biofilm and/or virulence mediators of P. aeruginosa known to affect biofilm formation in vitro and pathogenesis in vivo--bis-(3',5')-cyclic dimeric GMP (c-di-GMP), flagella, and quorum sensing--in a chinchilla model. We show that c-di-GMP overproduction has a positive impact on bacterial persistence, while quorum sensing increases virulence. We found no difference in persistence attributed to flagella. We conclude from these studies that a chinchilla otitis media model provides a means to evaluate pathogenic mediators of P. aeruginosa and that in vitro phenotypes should be examined in multiple infection systems to fully understand their role in disease.

Auditory Cortex Basal Activity Modulates Cochlear Responses in Chinchillas

PubMed Central

León, Alex; Elgueda, Diego; Silva, María A.; Hamamé, Carlos M.; Delano, Paul H.

2012-01-01

Background The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory nerve fibers. The functional role of the cortico-olivocochlear efferent system remains debated. We hypothesized that auditory cortex basal activity modulates cochlear and auditory-nerve afferent responses through the efferent system. Methodology/Principal Findings Cochlear microphonics (CM), auditory-nerve compound action potentials (CAP) and auditory cortex evoked potentials (ACEP) were recorded in twenty anesthetized chinchillas, before, during and after auditory cortex deactivation by two methods: lidocaine microinjections or cortical cooling with cryoloops. Auditory cortex deactivation induced a transient reduction in ACEP amplitudes in fifteen animals (deactivation experiments) and a permanent reduction in five chinchillas (lesion experiments). We found significant changes in the amplitude of CM in both types of experiments, being the most common effect a CM decrease found in fifteen animals. Concomitantly to CM amplitude changes, we found CAP increases in seven chinchillas and CAP reductions in thirteen animals. Although ACEP amplitudes were completely recovered after ninety minutes in deactivation experiments, only partial recovery was observed in the magnitudes of cochlear responses. Conclusions/Significance These results show that blocking ongoing auditory cortex activity modulates CM and CAP responses, demonstrating that cortico-olivocochlear circuits regulate auditory nerve and cochlear responses through a basal efferent tone. The diversity of the obtained effects suggests that there are at least two functional pathways from the auditory cortex to the cochlea. PMID:22558383

Nuclear Geoplosics Sourcebook. Volume IV. Part I. Empirical Analysis of Ground Motion from Above and Underground Explosions

DTIC Science & Technology

1979-03-01

for some detonations, for example, PLATYPUS , SHREW, and ERMINE, this secondary acceleration pulse is not evident in the data. *Maximum vertical...RADIAL C..) _j n ’U~n" -- m RINGTAIL \\ ,• • n MINK P "W o PLATYPUS \\ \\ •" p SHREW \\- .Cq HOGNOSERAD s ERMINEb; w CHINCHILLA \\ 0.10 1.0 10 102 DEPTH OF...h2xHOGNOSE RADIAL 0 _ 1 . - \\ \\\\ \\ m RINGTAIL n MINK a PLATYPUS p SHREW q HOGNOSE s ERMINE w CHINCHILLA 0.101I I I I I 1 LJI t. 10 30 DEPTH OF BURST, 102 ft

Histology of the ovary of Chinchilla lanigera in captivity.

PubMed

Sánchez-Toranzo, G; Torres-Luque, A; Gramajo-Bühler, M C; Bühler, M I

2014-08-01

Chinchilla, the lanigera variety in particular, is one of the most valuable rodents in the fur industry. The chinchilla ovary is morphologically similar to that of other South American hystricognath rodents, especially as regards its anatomy and, to a lesser degree, its histology. The presence of numerous primary follicles throughout the annual cycle suggests that a few of them are recruited to initiate growth and differentiation during folliculogenesis. Primary follicles with two or more oocytes are common; this is not the case with follicles at more advanced stages, suggesting that they do not develop. Only one or two large corpora lutea (CL) and three to five small or accessories CL were observed but no corpora albicans. The presence of accessory CL may reflect the importance of continuous hormonal production to support prolonged gestation. Atretic CL were also present, showing signs of degeneration in luteal cells. The interstitial cells distributed throughout the cortex were the main histological feature shared with other species, as stated in previous reports. Antral atresia was observed in all sizes of antral follicles while basal atresia was confined exclusively to smaller follicles. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of superior-canal opening on middle-ear input admittance and air-conducted stapes velocity in chinchilla

PubMed Central

Songer, Jocelyn E.; Rosowski, John J.

2009-01-01

The recent discovery of superior semicircular canal (SC) dehiscence syndrome as a clinical entity affecting both the auditory and vestibular systems has led to the investigation of the impact of a SC opening on the mechanics of hearing. It is hypothesized that the hole in the SC acts as a “third window” in the inner ear which shunts sound-induced stapes volume velocity away from the cochlea through the opening in the SC. To test the hypothesis and to understand the third window mechanisms the middle-ear input admittance and sound-induced stapes velocity were measured in chinchilla before and after surgically introducing a SC opening and after patching the opening. The extent to which patching returned the system to the presurgical state is used as a control criterion. In eight chinchilla ears a statistically significant, reversible increase in low-frequency middle-ear input admittance magnitude occurred as a result of opening the SC. In six ears a statistically significant reversible increase in stapes velocity was observed. Both of these changes are consistent with the hole creating a shunt pathway that increases the cochlear input admittance. PMID:16875223

The effect of superior-canal opening on middle-ear input admittance and air-conducted stapes velocity in chinchilla.

PubMed

Songer, Jocelyn E; Rosowski, John J

2006-07-01

The recent discovery of superior semicircular canal (SC) dehiscence syndrome as a clinical entity affecting both the auditory and vestibular systems has led to the investigation of the impact of a SC opening on the mechanics of hearing. It is hypothesized that the hole in the SC acts as a "third window" in the inner ear which shunts sound-induced stapes volume velocity away from the cochlea through the opening in the SC. To test the hypothesis and to understand the third window mechanisms the middle-ear input admittance and sound-induced stapes velocity were measured in chinchilla before and after surgically introducing a SC opening and after patching the opening. The extent to which patching returned the system to the presurgical state is used as a control criterion. In eight chinchilla ears a statistically significant, reversible increase in low-frequency middle-ear input admittance magnitude occurred as a result of opening the SC. In six ears a statistically significant reversible increase in stapes velocity was observed. Both of these changes are consistent with the hole creating a shunt pathway that increases the cochlear input admittance.

Chinchilla middle ear transmission matrix model and middle-ear flexibilitya)

PubMed Central

Ravicz, Michael E.; Rosowski, John J.

2017-01-01

The function of the middle ear (ME) in transforming ME acoustic inputs and outputs (sound pressures and volume velocities) can be described with an acoustic two-port transmission matrix. This description is independent of the load on the ME (cochlea or ear canal) and holds in either direction: forward (from ear canal to cochlea) or reverse (from cochlea to ear canal). A transmission matrix describing ME function in chinchilla, an animal commonly used in auditory research, is presented, computed from measurements of forward ME function: input admittance YTM, ME pressure gain GMEP, ME velocity transfer function HV, and cochlear input admittance YC, in the same set of ears [Ravicz and Rosowski (2012b). J. Acoust. Soc. Am. 132, 2437–2454; (2013a). J. Acoust. Soc. Am. 133, 2208–2223; (2013b). J. Acoust. Soc. Am. 134, 2852–2865]. Unlike previous estimates, these computations require no assumptions about the state of the inner ear, effectiveness of ME manipulations, or measurements of sound transmission in the reverse direction. These element values are generally consistent with physical constraints and the anatomical ME “transformer ratio.” Differences from a previous estimate in chinchilla [Songer and Rosowski (2007). J. Acoust. Soc. Am. 122, 932–942] may be due to a difference in ME flexibility between the two subject groups. PMID:28599566

Chinchilla middle-ear admittance and sound power: High-frequency estimates and effects of inner-ear modifications

PubMed Central

Ravicz, Michael E.; Rosowski, John J.

2012-01-01

The middle-ear input admittance relates sound power into the middle ear (ME) and sound pressure at the tympanic membrane (TM). ME input admittance was measured in the chinchilla ear canal as part of a larger study of sound power transmission through the ME into the inner ear. The middle ear was open, and the inner ear was intact or modified with small sensors inserted into the vestibule near the cochlear base. A simple model of the chinchilla ear canal, based on ear canal sound pressure measurements at two points along the canal and an assumption of plane-wave propagation, enables reliable estimates of YTM, the ME input admittance at the TM, from the admittance measured relatively far from the TM. YTM appears valid at frequencies as high as 17 kHz, a much higher frequency than previously reported. The real part of YTM decreases with frequency above 2 kHz. Effects of the inner-ear sensors (necessary for inner ear power computation) were small and generally limited to frequencies below 3 kHz. Computed power reflectance was ∼0.1 below 3.5 kHz, lower than with an intact ME below 2.5 kHz, and nearly 1 above 16 kHz. PMID:23039439

Chinchilla middle ear transmission matrix model and middle-ear flexibility.

PubMed

Ravicz, Michael E; Rosowski, John J

2017-05-01

The function of the middle ear (ME) in transforming ME acoustic inputs and outputs (sound pressures and volume velocities) can be described with an acoustic two-port transmission matrix. This description is independent of the load on the ME (cochlea or ear canal) and holds in either direction: forward (from ear canal to cochlea) or reverse (from cochlea to ear canal). A transmission matrix describing ME function in chinchilla, an animal commonly used in auditory research, is presented, computed from measurements of forward ME function: input admittance Y TM , ME pressure gain G MEP , ME velocity transfer function H V , and cochlear input admittance Y C , in the same set of ears [Ravicz and Rosowski (2012b). J. Acoust. Soc. Am. 132, 2437-2454; (2013a). J. Acoust. Soc. Am. 133, 2208-2223; (2013b). J. Acoust. Soc. Am. 134, 2852-2865]. Unlike previous estimates, these computations require no assumptions about the state of the inner ear, effectiveness of ME manipulations, or measurements of sound transmission in the reverse direction. These element values are generally consistent with physical constraints and the anatomical ME "transformer ratio." Differences from a previous estimate in chinchilla [Songer and Rosowski (2007). J. Acoust. Soc. Am. 122, 932-942] may be due to a difference in ME flexibility between the two subject groups.

Phosphorylcholine decreases early inflammation and promotes the establishment of stable biofilm communities of nontypeable Haemophilus influenzae strain 86-028NP in a chinchilla model of otitis media.

PubMed

Hong, Wenzhou; Mason, Kevin; Jurcisek, Joseph; Novotny, Laura; Bakaletz, Lauren O; Swords, W Edward

2007-02-01

Nontypeable Haemophilus influenzae (NTHi) is a leading causative agent of otitis media. Much of the inflammation occurring during NTHi disease is initiated by lipooligosaccharides (LOS) on the bacterial surface. Phosphorylcholine (PCho) is added to some LOS forms in a phase-variable manner, and these PCho(+) variants predominate in vivo. Thus, we asked whether this modification confers some advantage during infection. Virulence of an otitis media isolate (NTHi strain 86-028NP) was compared with that of an isogenic PCho transferase (licD) mutant using a chinchilla (Chinchilla lanigera) model of otitis media. Animals infected with NTHi 86-028NP licD demonstrated increased early inflammation and a delayed increase in bacterial counts compared to animals infected with NTHi 86-028NP. LOS purified from chinchilla-passed NTHi 86-028NP had increased PCho content compared to LOS purified from the inoculum. Both strains were recovered from middle ear fluids as long as 14 days postinfection. Biofilms were macroscopically visible in the middle ears of euthanized animals infected with NTHi 86-028NP 7 days and 14 days postchallenge. Conversely, less dense biofilms were observed in animals infected with NTHi 86-028NP licD 7 days postinfection, and none of the animals infected with NTHi 86-028NP licD had a visible biofilm by 14 days. Fluorescent antibody staining revealed PCho(+) variants within biofilms, similar to our prior results with tissue culture cells in vitro (S. L. West-Barnette, A. Rockel, and W. E. Swords, Infect. Immun. 74:1828-1836, 2006). Animals coinfected with equal proportions of both strains had equal persistence of each strain and somewhat greater severity of disease. We thus conclude that PCho promotes NTHi infection and persistence by reducing the host inflammatory response and by promoting formation of stable biofilm communities.

Phosphorylcholine Decreases Early Inflammation and Promotes the Establishment of Stable Biofilm Communities of Nontypeable Haemophilus influenzae Strain 86-028NP in a Chinchilla Model of Otitis Media▿ †

PubMed Central

Hong, Wenzhou; Mason, Kevin; Jurcisek, Joseph; Novotny, Laura; Bakaletz, Lauren O.; Swords, W. Edward

2007-01-01

Nontypeable Haemophilus influenzae (NTHi) is a leading causative agent of otitis media. Much of the inflammation occurring during NTHi disease is initiated by lipooligosaccharides (LOS) on the bacterial surface. Phosphorylcholine (PCho) is added to some LOS forms in a phase-variable manner, and these PCho+ variants predominate in vivo. Thus, we asked whether this modification confers some advantage during infection. Virulence of an otitis media isolate (NTHi strain 86-028NP) was compared with that of an isogenic PCho transferase (licD) mutant using a chinchilla (Chinchilla lanigera) model of otitis media. Animals infected with NTHi 86-028NP licD demonstrated increased early inflammation and a delayed increase in bacterial counts compared to animals infected with NTHi 86-028NP. LOS purified from chinchilla-passed NTHi 86-028NP had increased PCho content compared to LOS purified from the inoculum. Both strains were recovered from middle ear fluids as long as 14 days postinfection. Biofilms were macroscopically visible in the middle ears of euthanized animals infected with NTHi 86-028NP 7 days and 14 days postchallenge. Conversely, less dense biofilms were observed in animals infected with NTHi 86-028NP licD 7 days postinfection, and none of the animals infected with NTHi 86-028NP licD had a visible biofilm by 14 days. Fluorescent antibody staining revealed PCho+ variants within biofilms, similar to our prior results with tissue culture cells in vitro (S. L. West-Barnette, A. Rockel, and W. E. Swords, Infect. Immun. 74:1828-1836, 2006). Animals coinfected with equal proportions of both strains had equal persistence of each strain and somewhat greater severity of disease. We thus conclude that PCho promotes NTHi infection and persistence by reducing the host inflammatory response and by promoting formation of stable biofilm communities. PMID:17130253

The effect of superior canal dehiscence on cochlear potential in response to air-conducted stimuli in chinchilla

PubMed Central

Songer, Jocelyn E.; Rosowski, John J.

2006-01-01

A superior semicircular canal dehiscence (SCD) is a break or hole in the bony wall of the superior semicircular canal. Patients with SCD syndrome present with a variety of symptoms: some with vestibular symptoms, others with auditory symptoms (including low-frequency conductive hearing loss) and yet others with both. We are interested in whether or not mechanically altering the superior canal by introducing a dehiscence is sufficient to cause the low-frequency conductive hearing loss associated with SCD syndrome. We evaluated the effect of a surgically introduced dehiscence on auditory responses to air-conducted (AC) stimuli in 11 chinchilla ears. Cochlear potential (CP) was recorded at the round-window before and after a dehiscence was introduced. In each ear, a decrease in CP in response to low frequency (<2 kHz) sound stimuli was observed after the introduction of the dehiscence. The dehiscence was then patched with cyanoacrylate glue leading to a reversal of the dehiscence-induced changes in CP. The reversible decrease in auditory sensitivity observed in chinchilla is consistent with the elevated AC thresholds observed in patients with SCD. According to the ‘third-window’ hypothesis the SCD shunts sound-induced stapes velocity away from the cochlea, resulting in decreased auditory sensitivity to AC sounds. The data collected in this study are consistent with predictions of this hypothesis. PMID:16150562

[Two cases of Trichophyton mentagrophytes infection contracted from a hamster and a chinchilla].

PubMed

Hata, Y; Amagai, M; Naka, W; Harada, R; Nishikawa, T

2000-01-01

We report two cases of Trichophyton mentagrophytes infection. Case 1: A 10-year-old girl visited Tokyo Electric Power Hospital in June 1994 for evaluation of an erythematous lesion on her head. Three months of topical steroid therapy exacerbated the lesion with pustular formation. Histopathological and mycological examination revealed that the patient had tinea capitis caused by T. mentagrophytes. T. mentagrophytes was also isolated from her pet, a hamster. Case 2: A-14-year-old girl was referred to Shonan Clinic in January 1996 with scaly erythema on her face. She had been treated with neticonazole hydrochloride at another clinic, but the lesion became worse. Direct microscopic examination of the scale was negative at that time, so treatment with topical steroid was started. After 10 days, the lesion was almost cured, but one month later it recurred with an annular distribution. KOH preparation of the scale revealed mycelia and T. mentagrophytes was isolated on culture. T. mentagrophytes was also isolated from her pet, a chinchilla. In both cases, the oral administration of itraconazole at 50 mg/day was effective. The isolated pathogen was identified as Arthroderma vanbreuseghemii with species-specific primers of chitin synthase 1 gene. T. mentagrophytes is one of the most common dermatophytes isolated from man and animals. Rodents like the hamster and the chinchilla have recently become popular as pets in Japan. We should be aware that rodents may carry this kind of fungal pathogen as they become even more popular as pets.

Research in Prevention and Treatment of Noise-Induced Hearing Loss (NIHL)

DTIC Science & Technology

2016-06-01

The current study identified optimal protective D-methionine (D-met) dose and delayed time response from steady state and impulse noise -induced hearing loss (NIHL) in groups of Chinchillas laniger (n=10/group).

Isolation and amino acid sequences of opossum vasoactive intestinal polypeptide and cholecystokinin octapeptide.

PubMed Central

Eng, J; Yu, J; Rattan, S; Yalow, R S

1992-01-01

Evolutionary history suggests that the marsupials entered South America from North America about 75 million years ago and subsequently dispersed into Australia before the separation between South America and Antarctica-Australia. A question of interest is whether marsupial peptides resemble the corresponding peptides of Old or New World mammals. Previous studies had shown that "little" gastrin of the North American marsupial, the opossum, is identical in length to that of the New World mammals, the guinea pig and chinchilla. In this report, we demonstrate that opossum cholecystokinin octapeptide, like that of the Australian marsupials, the Eastern quoll and the Tamar wallaby, is identical to the cholecystokinin octapeptide of Old World mammals and differs from that of the guinea pig and chinchilla. However, opossum vasoactive intestinal polypeptide differs from the usual Old World mammalian vasoactive intestinal polypeptide in five sites: [sequence; see text]. PMID:1542675

Axonal recordings from medial superior olive neurons obtained from the lateral lemniscus of the chinchilla (Chinchilla laniger).

PubMed

Bremen, Peter; Joris, Philip X

2013-10-30

Interaural time differences (ITDs) are a major cue for localizing low-frequency (<1.5 kHz) sounds. Sensitivity to this cue first occurs in the medial superior olive (MSO), which is thought to perform a coincidence analysis on its monaural inputs. Extracellular single-neuron recordings in MSO are difficult to obtain because (1) MSO action potentials are small and (2) a large field potential locked to the stimulus waveform hampers spike isolation. Consequently, only a limited number of studies report MSO data, and even in these studies data are limited in the variety of stimuli used, in the number of neurons studied, and in spike isolation. More high-quality data are needed to better understand the mechanisms underlying neuronal ITD-sensitivity. We circumvented these difficulties by recording from the axons of MSO neurons in the lateral lemniscus (LL) of the chinchilla, a species with pronounced low-frequency sensitivity. Employing sharp glass electrodes we successfully recorded from neurons with ITD sensitivity: the location, response properties, latency, and spike shape were consistent with an MSO axonal origin. The main difficulty encountered was mechanical stability. We obtained responses to binaural beats and dichotic noise bursts to characterize the best delay versus characteristic frequency distribution, and compared the data to recordings we obtained in the inferior colliculus (IC). In contrast to most reports in other rodents, many best delays were close to zero ITD, both in MSO and IC, with a majority of the neurons recorded in the LL firing maximally within the presumed ethological ITD range.

Structural and Functional Studies of the Protamine 2-Zinc Complex from Syrian Gold Hamster (Mesocricetus Auratus) Spermatids and Sperm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolan, Cheryl E.

The research described in this dissertation consists of four major areas: (1) sequence analysis of protamine 2 from Muroid rodents to identify potential zinc-binding domain(s) of protamine 2; (2) structural studies of the protamine 2-zinc complex from Syrian Gold hamster sperm and spermatids to elucidate the role of zinc during spermiogenesis; (3) structural studies of an unique protamine 2-zinc complex from chinchilla sperm; and (4) Nuclear Magnetic Resonance (NMR) studies of soluble complexes of hairpin oligonucleotides with synthetic arginine-rich peptides or protamine 1 isolated from bull sperm. First, zinc was quantitated in spermatids and sperm by Proton-Induced X-ray Emission (PIXE)more » to determine whether zinc is present in the early stages of spermiogenesis. The PIXE results revealed the zinc content varies proportionately with the amount of protamine 2 in both spermatid and sperm nuclei. An exception was chinchilla sperm containing twice the amount of protamine 2 than zinc. Further analyses by PIXE and X-ray Absorption Spectroscopy (XAS) of zinc bound to protamines isolated from hamster sperm confirmed the majority of the zinc is bound to protamine and identified the zinc ligands of protamine 2 in hamster spermatids and sperm in vivo. These studies established that zinc is bound to the protamine 2 precursor in hamster spermatids and the coordination of zinc by protamine 2 changes during spermiogenesis. Finally, the sequence analysis combined with the XAS results suggest that the zinc-binding domain in protamine 2 resides in the amino-terminus. Similar analyses of chinchilla sperm by XAS were performed to clarify the unusual PIXE results and revealed that chinchilla has an atypical protamine 2-zinc structure. Two protamine 2 molecules coordinate one zinc atom, forming homodimers that facilitate the binding of protamine 2 to DNA and provide an organizational scheme that would accommodate the observed species-specific protamine stoichiometry in mammalian sperm. Based on these results, we propose the binding of zinc to protamine 2 molecules stabilizes a dimerization domain in other mammalian sperm. Future experiments will use the knowledge we gained of the interactions between protamine 1 and DNA from the NMR studies to obtain structural data for the DNA-protamine 2-zinc complex.« less

Phosphorescence In Bacillus Spores

DTIC Science & Technology

2003-07-01

commonly causing acute otitis media (middle ear infections) is present in an animal model. We will briefly review this application since it shows that...causing acute otitis media in a chinchilla model. Laryngoscope.110, 1119-1123, (2000). 2. C.D. Bluestone, J.O. Klein, Otitis media , atelesctasis

Immunogenicity of Nontypeable Haemophilus influenzae Outer Membrane Vesicles and Protective Ability in the Chinchilla Model of Otitis Media.

PubMed

Winter, Linda E; Barenkamp, Stephen J

2017-10-01

Outer membrane vesicles (OMVs) produced by Gram-negative bacteria are enriched in several outer membrane components, including major and minor outer membrane proteins and lipooligosaccharide. We assessed the functional activity of nontypeable Haemophilus influenzae (NTHi) OMV-specific antisera and the protective ability of NTHi OMVs as vaccine antigens in the chinchilla otitis media model. OMVs were purified from three HMW1/HMW2-expressing NTHi strains, two of which were also engineered to overexpress Hia proteins. OMV-specific antisera raised in guinea pigs were assessed for their ability to mediate killing of representative NTHi in an opsonophagocytic assay. The three OMV-specific antisera mediated killing of 18 of 65, 24 of 65, and 30 of 65 unrelated HMW1/HMW2-expressing NTHi strains. Overall, they mediated killing of 39 of 65 HMW1/HMW2-expressing strains. The two Hia-expressing OMV-specific antisera mediated killing of 17 of 25 and 14 of 25 unrelated Hia-expressing NTHi strains. Overall, they mediated killing of 20 of 25 Hia-expressing strains. OMVs from prototype NTHi strain 12 were used to immunize chinchillas and the course of middle ear infection was monitored following intrabullar challenge with the homologous strain. All control animals developed culture-positive otitis media, as did two of three HMW1/HMW2-immunized animals. All OMV-immunized animals, with or without supplemental HMW1/HMW2 immunization, were completely protected against otitis media. NTHi OMVs are the first immunogens examined in this model that provided complete protection with sterile immunity after NTHi strain 12 challenge. These data suggest that NTHi OMVs hold significant potential as components of protective NTHi vaccines, possibly in combination with HMW1/HMW2 proteins. Copyright © 2017 American Society for Microbiology.

Roles of autolysin and pneumolysin in middle ear inflammation caused by a type 3 Streptococcus pneumoniae strain in the chinchilla otitis media model.

PubMed Central

Sato, K; Quartey, M K; Liebeler, C L; Le, C T; Giebink, G S

1996-01-01

Streptococcus pneumoniae cell wall and pneumolysin are important contributors to pneumococcal pathogenicity in some animal models. To further explore these factors in middle ear inflammation caused by pneumococci, penicillin-induced inflammatory acceleration was studied by using three closely related pneumococcal strains: a wild-type 3 strain (WT3), its pneumolysin-negative derivative (P-1), and into autolysin-negative derivative (A-1). Both middle ears of chinchillas were inoculated with one of the three pneumococcal strains. During the first 12 h, all three strains grew in vivo at the same rate, and all three strains induced similar inflammatory cell responses in middle ear fluid (MEF). Procaine penicillin G was given as 12 h to one-half of the animals in each group, and all treated chinchillas had sterile MEF at 24 h. Penicillin significantly accelerated MEF inflammatory cell influx into WT3-and P-1-infected ears at 18 and 24 h in comparison with the rate for penicillin-treated A-1-infected ears. Inflammatory cell influx was slightly, but not significantly, greater after treatment of WT3 infection than after treatment of P-1 infection. Interleukin (IL)-1beta and IL-6, but not IL-8, concentrations in MEF at 24 h reflected the penicillin effect on MEF inflammatory cells; however, differences between treatment groups were not significant. Results suggest that pneumococcal otitis media pathogenesis is triggered principally by the inflammatory effects of intact and lytic cell wall products in the middle ear, with at most a modes additional pneumolysin effect. Investigation strategies that limit the release of these products or neutralize them warrant further investigation. PMID:8606070

Passage of albumin from the middle ear to the inner ear in otitis media in the chinchilla

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, B.; Goycoolea, M.V.; Schleivert, P.M.

1981-08-01

A study of the permeability of the middle ear-inner ear interface for macromolecules was carried out in chinchillas with open and obstructed eustachian tubes utilizing tritiated human serum albumin and immunoelectrophoresis. Tritiated albumin was placed in the round window niche area or normal animals and animals in which the eustachian tubes had been obstructed for 24 hours or 14 days. The tritiated albumin was allowed to remain in the middle ear cavity for 24 hours, Samples of middle ear effusion, perilymph, blood and cerebrospinal fluid were collected and measured for radioactivity. Radioactivity was demonstrated in the perilymph. Samples of middlemore » ear effusions and perilymph were also studied by immunoelectrophoresis with goat antihuman albumin. Albumin placed in the round window niche of an experimental animal could be recovered unchanged in the perilymph. The results suggest a pathophysiologic explanation for the association of otitis media and sensorineural hearing loss or endolymphatic hydrops.« less

The Effect of Impulse Intensity and the Number of Impulses on Hearing and Cochlear Pathology in the Chinchilla.

DTIC Science & Technology

1985-06-01

34 "+" :-’ " ’ .. . . . .".. . . . . . "’ " ".... ""....... .. -" T " ’ ... . .. " " .. Col G. Stebbing Canadian Army Liaison Office -’.USDAO- AMLO , US Embassy Bldg 602 Box 36 Fort Rucker, AL 36362

77 FR 28799 - Animal Welfare; Retail Pet Stores and Licensing Exemptions

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-16

... as pets are considered retail pet stores: Dogs, cats, rabbits, guinea pigs, hamsters, gerbils, rats... following animals are sold or offered for sale, at retail, for use as pets: Dogs, cats, rabbits, guinea pigs... dogs, cats, birds, rabbits, hamsters, guinea pigs, gophers, domestic ferrets, chinchilla, rats, and...

Malocclusions in guinea pigs, chinchillas and rabbits

PubMed Central

Legendre, Loïc F.J.

2002-01-01

The types of malocclusions encountered in rodents and lagomorphs are classified. Diagnosis, treatment, and prognosis are reviewed. Some malocclusions are curable, whereas others can only be controlled. The need to perform a complete oral examination and to find a cause for the condition is stressed, as it will seriously affect the prognosis. PMID:12001507

(Un)Disciplined futures: Women of color feminism as a disruptive to white affect studies.

PubMed

Garcia-Rojas, Claudia

2017-07-03

The aim of this article is to demonstrate how women of color feminism predates and disrupts dominant dialogues in the field of White affect studies. I introduce the concept of White affect studies as an arena of inquiry that draws from Western-European theories and literatures and architects a sociopolitical structure of affect that positions White affects as universal. Scholars contributing to the field of White affect studies posit theories of affect, embodiment, subjectivity, phenomenology, violence, war, and more, while disregarding the theoretical contributions made by women of color feminism in thinking through these notions and social issues. This is done by engaging in a citational practice that results in an epistemic erasure of women of color feminist thought. The voices of women of color feminists are thus disqualified, and their theoretical contributions are not acknowledged as significant or relevant in conceptualizing affect, affective economies, and the social. By turning to the writings of women of color feminists, I demonstrate how their theories on embodiment, subjectivity, and social structures predate the institutionalization of White affect studies. Feminists of color from the past and present have and continue to theorize through a language of self their experiences as subjects embedded within matrices of violence, power, and pleasure. Lorde, Martinez, and Chinchilla write about the ways in which lesbian and queer women of color institute different affects that counter dominant structures of emotion, systems of power, and heterosexual modes of being. In developing conceptual methodologies, Lorde, Martinez, and Chinchilla are able to weave into the dominant discursive logic a language of self that both introduces new queer subjectivities, while reinterpreting existing forms of thought, thereby contesting mainstream economies of White affects and White affect studies. It is through a language of self that Lorde, Martinez, and Chinchilla develop an ethic of survival that countermobilizes against White hegemonic apparatuses.

Factors Affecting Loss of Tympanic Membrane Mobility in Acute Otitis Media Model of Chinchilla

PubMed Central

Guan, Xiying; Chen, Yongzheng; Gan, Rong Z.

2014-01-01

Recently we reported that middle ear pressure (MEP), middle ear effusion (MEE), and ossicular changes each contribute to the loss of tympanic membrane (TM) mobility in a guinea pig model of acute otitis media (AOM) induced by S. pneumoniae (Guan and Gan, 2013). However, it is not clear how those factors vary along the course of the disease and whether those effects are reproducible in different species. In this study, a chinchilla AOM model was produced by transbullar injection of Haemophilus influenzae. Mobility of the TM at the umbo was measured by laser vibrometry in two treatment groups: 4 days (4D) and 8 days (8D) post inoculation. These time points represent relatively early and later phases of AOM. In each group, the vibration of the umbo was measured at three experimental stages: unopened, pressure-released, and effusion-removed ears. The effects of MEP and MEE and middle ear structural changes were quantified in each group by comparing the TM mobility at one stage with that of the previous stage. Our findings show that the factors affecting TM mobility do change with the disease time course. The MEP was the dominant contributor to reduction of TM mobility in 4D AOM ears, but showed little effect in 8D ears when MEE filled the tympanic cavity. MEE was the primary factor affecting TM mobility loss in 8D ears, but affected the 4D ears only at high frequencies. After the release of MEP and removal of MEE, residual loss of TM mobility was seen mainly at low frequencies in both 4D and 8D ears, and was associated with middle ear structural changes. Our findings establish that the factors contributing to TM mobility loss in the chinchilla ear were similar to those we reported previously for the guinea pig ears with AOM. Outcomes did not appear to differ between the two major bacterial species causing AOM in these animal models. PMID:24406734

Mechanical Damage of Tympanic Membrane in Relation to Impulse Pressure Waveform – A Study in Chinchillas

PubMed Central

Gan, Rong Z.; Nakmali, Don; Ji, Xiao D.; Leckness, Kegan; Yokell, Zachary

2016-01-01

Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4±0.7 vs. 9.1±1.7 psi or 181±1.6 vs. 190±1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure. PMID:26807796

Testing coherent reflection in chinchilla: Auditory-nerve responses predict stimulus-frequency emissions

PubMed Central

Shera, Christopher A.; Tubis, Arnold; Talmadge, Carrick L.

2008-01-01

Coherent-reflection theory explains the generation of stimulus-frequency and transient-evoked otoacoustic emissions by showing how they emerge from the coherent “backscattering” of forward-traveling waves by mechanical irregularities in the cochlear partition. Recent published measurements of stimulus-frequency otoacoustic emissions (SFOAEs) and estimates of near-threshold basilar-membrane (BM) responses derived from Wiener-kernel analysis of auditory-nerve responses allow for comprehensive tests of the theory in chinchilla. Model predictions are based on (1) an approximate analytic expression for the SFOAE signal in terms of the BM traveling wave and its complex wave number, (2) an inversion procedure that derives the wave number from BM traveling waves, and (3) estimates of BM traveling waves obtained from the Wiener-kernel data and local scaling assumptions. At frequencies above 4 kHz, predicted median SFOAE phase-gradient delays and the general shapes of SFOAE magnitude-versus-frequency curves are in excellent agreement with the measurements. At frequencies below 4 kHz, both the magnitude and the phase of chinchilla SFOAEs show strong evidence of interference between short- and long-latency components. Approximate unmixing of these components, and association of the long-latency component with the predicted SFOAE, yields close agreement throughout the cochlea. Possible candidates for the short-latency SFOAE component, including wave-fixed distortion, are considered. Both empirical and predicted delay ratios (long-latency SFOAE delay∕BM delay) are significantly less than 2 but greater than 1. Although these delay ratios contradict models in which SFOAE generators couple primarily into cochlear compression waves, they are consistent with the notion that forward and reverse energy propagation in the cochlea occurs predominantly by means of traveling pressure-difference waves. The compelling overall agreement between measured and predicted delays suggests that the coherent-reflection model captures the dominant mechanisms responsible for the generation of reflection-source otoacoustic emissions. PMID:18646984

Experimental investigation of the role of thyrocalcitonin in the prophylaxis of disturbances in the water-salt and mineral metabolism during a 30-day hypokinesia

NASA Technical Reports Server (NTRS)

Shashkov, V. S.; Yegorov, B. B.; Dmitriyev, B. S.; Volozhin, A. N.; Krotov, B. P.

1979-01-01

The effect of thyrocalcitonin (TCT) injections on the metabolism of water and electrolytes in free-moving and immobilized chinchilla hares is described. Calcium excretion from immobilized animals was elevated, but normalized in those also receiving TCT injections. TCT also normalized water content and excretion rates.

Low-frequency tone-pip-evoked otoacoustic emissions originate over a broad cochlear region in chinchillas

NASA Astrophysics Data System (ADS)

Charaziak, Karolina K.; Siegel, Jonathan H.

2015-12-01

Otoacoustic emissions evoked with transient sounds (TEOAEs) are believed to originate within the tonotopic region of the stimulus in the cochlea via the same mechanisms as emissions evoked with single tones. However, we found that emissions evoked by low frequency (< 3 kHz) single-tones have an extended region of generation (> 6 mm) in chinchillas (Charaziak and Siegel, 2014, ARO Abst., 119). Here we test whether a broad region of generation for low-frequency stimuli is also a characteristic of TEOAEs evoked with 1-kHz tone pips extracted with compression and suppression methods. The TEOAE could be revealed with moderate level suppressors with frequencies extending beyond the stimulus bandwidth (up to 12.1 kHz), with the largest responses obtained with 3.1 - 4.1 kHz suppressors. There was a consistent decline in group delays of suppressor-revealed TEOAEs with increasing suppressor frequency, as expected if higher-frequency suppressors acted on more basal TEOAE generators. Effects of mid- to high-frequency acoustic trauma on TEOAE levels confirm the notion that the suppressors interact with emission components arising near the tonotopic place of the suppressor.

Replication of type 5 adenovirus promotes middle ear infection by Streptococcus pneumoniae in the chinchilla model of otitis media

PubMed Central

Murrah, Kyle A.; Turner, Roberta L.; Pang, Bing; Perez, Antonia C.; Reimche, Jennifer L.; King, Lauren B.; Wren, John; Gandhi, Uma; Swords, W. Edward; Ornelles, David A.

2015-01-01

Adenoviral infection is a major risk factor for otitis media. We hypothesized that adenovirus promotes bacterial ascension into the middle ear through the disruption of normal function in the Eustachian tubes due to inflammation-induced changes. An intranasal infection model of the chinchilla was used to test the ability of type 5 adenovirus to promote middle ear infection by Streptococcus pneumoniae. The hyperinflammatory adenovirus mutant dl327 and the nonreplicating adenovirus mutant H5wt300ΔpTP were used to test the role of inflammation and viral replication, respectively, in promotion of pneumococcal middle ear infection. Precedent infection with adenovirus resulted in a significantly greater incidence of middle ear disease by S. pneumoniae as compared to nonadenovirus infected animals. Infection with the adenovirus mutant dl327 induced a comparable degree of bacterial ascension into the middle ear as did infection with the wild-type virus. By contrast, infection with the nonreplicating adenovirus mutant H5wt300ΔpTP resulted in less extensive middle ear infection compared to the wild-type adenovirus. We conclude that viral replication is necessary for adenoviral-induced pneumococcal middle ear disease. PMID:25251686

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs.

PubMed

Greco, Mariana; Kemppainen, Minna; Pose, Graciela; Pardo, Alejandro

2015-09-02

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

Middle ear function and cochlear input impedance in chinchilla

PubMed Central

Slama, Michaël C. C.; Ravicz, Michael E.; Rosowski, John J.

2010-01-01

Simultaneous measurements of middle ear-conducted sound pressure in the cochlear vestibule PV and stapes velocity VS have been performed in only a few individuals from a few mammalian species. In this paper, simultaneous measurements of PV and VS in six chinchillas are reported, enabling computation of the middle ear pressure gain GME (ratio of PV to the sound pressure in the ear canal PTM), the stapes velocity transfer function SVTF (ratio of the product of VS and area of the stapes footplate AFP to PTM), and, for the first time, the cochlear input impedance ZC (ratio of PV to the product of VS and AFP) in individuals. |GME| ranged from 25 to 35 dB over 125 Hz–8 kHz; the average group delay between 200 Hz and 10 kHz was about 52 μs. SVTF was comparable to that of previous studies. ZC was resistive from the lowest frequencies up to at least 10 kHz, with a magnitude on the order of 1011 acoustic ohms. PV, VS, and the acoustic power entering the cochlea were good predictors of the shape of the audiogram at frequencies between 125 Hz and 2 kHz. PMID:20329840

Fiber diameter distributions in the chinchilla's ampullary nerves

NASA Technical Reports Server (NTRS)

Hoffman, Larry F.; Honrubia, Vicente

2002-01-01

A morphometric study of the chinchilla's ampullary nerves was conducted to produce an unbiased accounting of the diameter distribution of their constituent fibers. Diameter analyses were determined from 1 microm plastic-embedded nerve sections taken at a plane immediately proximal to the sensory epithelium. We found these nerves to be composed of 2094+/-573 fibers, having diameters that ranged from 0.5 to 8 microm. The distributions of diameters were positively skewed, where approximately 75% of the fibers were found to have diameters less than 3.5 microm. An analysis of the spatial distribution of diameters within the nerve section revealed that the lateralmost areas of the nerve contained larger fractions of fibers within the smallest diameter quintiles, and the central area harbored greater proportions of the larger diameter quintiles. However, significant fractions of all quintiles were found in all areas. These data were integrated with available data of Fernandez et al. (1998) to produce diameter estimates of calyx, dimorphic, and bouton morphology subpopulations. In view of a general relationship between diameter, innervation locus, and an afferent's physiologic characteristics, these data provide the basis for developing a perspective for the in situ distribution of afferent response dynamics.

Atheromic and lymphoplasmacytic effects of Mangifera indica methanolic leaf extract on the heart of chinchilla rabbits.

PubMed

Ngokere, Anthony Ajuluchukwu; Ezeofor, Peace Chinelo; Okoye, Jude Ogechukwu; Chukwuanukwu, Rebecca Chinyelu

2015-11-01

The aim of this study was to evaluate the effect of methanol extract of Mangifera indica on serum concentration of creatine kinase, total white blood cell (WBC) count and lymphocyte counts and the micro-anatomical architecture of the heart in chinchilla rabbits in order to find its safe and toxic levels. A total of 24 Chinchilla rabbits aged 10-14 weeks, divided into four experimental groups were orally administered the doses of none, 500, 1000 and 1500 mg/kg body weight of the methanol extract of M. indica, respectively, for 28 days. The modified International Federation of Clinical Chemistry (IFCC) method was used to estimate the serum concentration of creatine kinase (CK (-MB)) while the haematology auto-analyser was used to estimate the total WBC count and lymphocyte count. The estimated values were subjected to analysis of variance using the SPSS software application (version 16) and expressed as mean±standard deviation. Tissue sections were stained by phosphotungstic acid haematoxylin and haematoxylin and eosin staining techniques. The result showed significant increases in serum concentrations of CK (-MB) (12.05±3.11-21.55±9.93 U/L) and total WBC count (5.33±0.66-6.51±0.38 103/μL) when the control group was compared with the treated groups (p<0.05). A significant dose-dependent decrease in the weight of the heart (0.053±0.00-0.041±0.003 kg) was also observed (p<0.05). An insignificant increase was observed in the lymphocyte count (4.47±0.94-5.18±0.76 103/μL) in the blood when compared with the control group (p>0.05). Significant differences were also observed in the body weight of the treated groups (p<0.05). The histopathological findings include atheroma, attenuated vasculature, lymphoplasmacytic infiltrates, necrotic and fibrotic vascular walls. Thus, M. indica is indicated to have some health benefits at 500 mg/kg and shows toxicity on the micro-architecture of the heart at a concentration of ≥1000 mg/kg.

A physiological frequency-position map of the chinchilla cochlea.

PubMed

Müller, Marcus; Hoidis, Silvi; Smolders, Jean W T

2010-09-01

Accumulating evidence indicates that mammalian cochlear frequency-position maps (location of maximum vibration of the basilar membrane as a function of frequency) depend on the physiological condition of the inner ear. Cochlear damage desensitizes the ear, after the damage the original location of maximum vibration is tuned to a lower sound frequency. This suggests that frequency-position maps, derived from such desensitized ears, are shifted to lower frequencies, corresponding to a shift of the basilar membrane vibration pattern towards the base for a given stimulus frequency. To test this hypothesis, we re-mapped the cochlear frequency-position map in the chinchilla. We collected frequency-position data from chinchillas in normal physiological condition ("physiological map") and compared these to data previously established from sound overexposed ears ("anatomical map"). The characteristic frequency (CF) of neurons in the cochlear nucleus was determined. Horse-radish peroxidase (HRP) or biocytin (BCT) were injected iontophoretically to trace auditory nerve fibers towards their innervation site in the organ of Corti. The relationship between distance from the base (d, percent) and frequency (f, kHz) was described best by a simple exponential function: d = 61.2 - 42.2 x log(f). The slope of the function was 2.55 mm/octave. Compared to the "anatomical map", the "physiological map" was shifted by about 0.3 octaves to higher frequencies corresponding to a shift of the basilar membrane vibration pattern of 0.8 mm towards the apex for a given stimulus frequency. Our findings affirm that frequency-position maps in the mammalian cochlea depend on the condition of the inner ear. Damage-induced desensitization in mammalian inner ears results in similar shifts of CF (about 0.5 octaves) but different shifts of the maximum of the vibration pattern towards the base at given frequencies, dependent on the mapping constant of the species, longer basilar membranes showing a larger basal shift. Furthermore, the results substantiate the notion that "crowding" at lower frequencies appears to be a specialization rather than a general feature. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Mechanical damage of tympanic membrane in relation to impulse pressure waveform - A study in chinchillas.

PubMed

Gan, Rong Z; Nakmali, Don; Ji, Xiao D; Leckness, Kegan; Yokell, Zachary

2016-10-01

Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4 ± 0.7 vs. 9.1 ± 1.7 psi or 181 ± 1.6 vs. 190 ± 1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

High-frequency tone-pip-evoked otoacoustic emissions in chinchillas

NASA Astrophysics Data System (ADS)

Siegel, Jonathan H.; Charaziak, Karolina K.

2015-12-01

We measured otoacoustic emissions in anesthetized chinchillas evoked by short (1 ms) high-frequency (4 kHz) tone-pips (TEOAE) using either a compression or suppression method to separate the stimulus from the emission. Both methods revealed consistent features of the TEOAEs. The main spectral band of the emission generally corresponded to the spectrum of the stimulus, exhibiting a group delay similar to that of SFOAEs [9]. However, a second spectral band below 1.5 kHz, clearly separated from the low-frequency cut-off frequency of the stimulus spectrum, corresponded to an amplitude modulation of the waveform of the TEOAE. The group delay of this low-frequency band was similar to that of the main band near the probe frequency. The average level and group delay of the main band declined monotonically when revealed as the suppressor frequency was raised above the probe. The low-frequency band was more sensitive than the main band to shifts in compound action potential thresholds near the probe frequency induced by acute exposure to intense tones. Taken together, the experiments indicate that both the main and low-frequency bands of the TEOAE are generated primarily near the cochlear region maximally stimulated by the probe, but that significant contributions arise over a large region even more basal.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

PubMed Central

Greco, Mariana; Kemppainen, Minna; Pose, Graciela; Pardo, Alejandro

2015-01-01

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds. PMID:26364643

Middle Ear Fluid Cytokine and Inflammatory Cell Kinetics in the Chinchilla Otitis Media Model

PubMed Central

Sato, Katsuro; Liebeler, Carol L.; Quartey, Moses K.; Le, Chap T.; Giebink, G. Scott

1999-01-01

Streptococcus pneumoniae is the most frequent microbe causing middle ear infection. The pathophysiology of pneumococcal otitis media has been characterized by measurement of local inflammatory mediators such as inflammatory cells, lysozyme, oxidative metabolic products, and inflammatory cytokines. The role of cytokines in bacterial infection has been elucidated with animal models, and interleukin (IL)-1β, IL-6, and IL-8 and tumor necrosis factor alpha (TNF-α) are recognized as being important local mediators in acute inflammation. We characterized middle ear inflammatory responses in the chinchilla otitis media model after injecting a very small number of viable pneumococci into the middle ear, similar to the natural course of infection. Middle ear fluid (MEF) concentrations of IL-1β, IL-6, IL-8, and TNF-α were measured by using anti-human cytokine enzyme-linked immunosorbent assay reagents. IL-1β showed the earliest peak, at 6 h after inoculation, whereas IL-6, IL-8, and TNF-α concentrations were increasing 72 h after pneumococcal inoculation. IL-6, IL-8, and TNF-α but not IL-1β concentrations correlated significantly with total inflammatory cell numbers in MEF, and all four cytokines correlated significantly with MEF neutrophil concentration. Several intercytokine correlations were significant. Cytokines, therefore, participate in the early middle ear inflammatory response to S. pneumoniae. PMID:10085040

Middle-ear velocity transfer function, cochlear input immittance, and middle-ear efficiency in chinchilla.

PubMed

Ravicz, Michael E; Rosowski, John J

2013-10-01

The transfer function H(V) between stapes velocity V(S) and sound pressure near the tympanic membrane P(TM) is a descriptor of sound transmission through the middle ear (ME). The ME power transmission efficiency (MEE), the ratio of sound power entering the cochlea to power entering the middle ear, was computed from H(V) measured in seven chinchilla ears and previously reported measurements of ME input admittance Y(TM) and ME pressure gain G(MEP) [Ravicz and Rosowski, J. Acoust. Soc. Am. 132, 2437-2454 (2012); J. Acoust. Soc. Am. 133, 2208-2223 (2013)] in the same ears. The ME was open, and a pressure sensor was inserted into the cochlear vestibule for most measurements. The cochlear input admittance Y(C) computed from H(V) and G(MEP) is controlled by a combination of mass and resistance and is consistent with a minimum-phase system up to 27 kHz. The real part Re{Y(C)}, which relates cochlear sound power to inner-ear sound pressure, decreased gradually with frequency up to 25 kHz and more rapidly above that. MEE was about 0.5 between 0.1 and 8 kHz, higher than previous estimates in this species, and decreased sharply at higher frequencies.

Middle-ear velocity transfer function, cochlear input immittance, and middle-ear efficiency in chinchilla

PubMed Central

Ravicz, Michael E.; Rosowski, John J.

2013-01-01

The transfer function HV between stapes velocity VS and sound pressure near the tympanic membrane PTM is a descriptor of sound transmission through the middle ear (ME). The ME power transmission efficiency (MEE), the ratio of sound power entering the cochlea to power entering the middle ear, was computed from HV measured in seven chinchilla ears and previously reported measurements of ME input admittance YTM and ME pressure gain GMEP [Ravicz and Rosowski, J. Acoust. Soc. Am. 132, 2437–2454 (2012); J. Acoust. Soc. Am. 133, 2208–2223 (2013)] in the same ears. The ME was open, and a pressure sensor was inserted into the cochlear vestibule for most measurements. The cochlear input admittance YC computed from HV and GMEP is controlled by a combination of mass and resistance and is consistent with a minimum-phase system up to 27 kHz. The real part Re{YC}, which relates cochlear sound power to inner-ear sound pressure, decreased gradually with frequency up to 25 kHz and more rapidly above that. MEE was about 0.5 between 0.1 and 8 kHz, higher than previous estimates in this species, and decreased sharply at higher frequencies. PMID:24116422

Inner-ear sound pressures near the base of the cochlea in chinchilla: Further investigation

PubMed Central

Ravicz, Michael E.; Rosowski, John J.

2013-01-01

The middle-ear pressure gain GMEP, the ratio of sound pressure in the cochlear vestibule PV to sound pressure at the tympanic membrane PTM, is a descriptor of middle-ear sound transfer and the cochlear input for a given stimulus in the ear canal. GMEP and the cochlear partition differential pressure near the cochlear base ΔPCP, which determines the stimulus for cochlear partition motion and has been linked to hearing ability, were computed from simultaneous measurements of PV, PTM, and the sound pressure in scala tympani near the round window PST in chinchilla. GMEP magnitude was approximately 30 dB between 0.1 and 10 kHz and decreased sharply above 20 kHz, which is not consistent with an ideal transformer or a lossless transmission line. The GMEP phase was consistent with a roughly 50-μs delay between PV and PTM. GMEP was little affected by the inner-ear modifications necessary to measure PST. GMEP is a good predictor of ΔPCP at low and moderate frequencies where PV ⪢ PST but overestimates ΔPCP above a few kilohertz where PV ≈ PST. The ratio of PST to PV provides insight into the distribution of sound pressure within the cochlear scalae. PMID:23556590

Measurements of three-dimensional shape and sound-induced motion of the chinchilla tympanic membrane

PubMed Central

Rosowski, John J; Dobrev, Ivo; Khaleghi, Morteza; Lu, Weina; Cheng, Jeffrey Tao; Harrington, Ellery; Furlong, Cosme

2013-01-01

Opto-electronic computer holographic measurements were made of the tympanic membrane (TM) in cadaveric chinchillas. Measurements with two laser wavelengths were used to compute the 3D-shape of the TM. Single laser wavelength measurements locked to eight distinct phases of a tonal stimulus were used to determine the magnitude and the relative phase of the surface displacements. These measurements were made at over 250,000 points on the TM surface. The measured motions contained spatial phase variations consistent with relatively low-order (large spatial frequency) modal motions and smaller magnitude higher-order (smaller spatial frequency) motions that appear to travel, but may also be explained by losses within the membrane. The measurement of shape and thin shell theory allowed us to separate the measured motions into those components orthogonal to the plane of the tympanic ring, and those components within the plane of the tympanic ring based on the 3D-shape. The predicted in-plane motion components are generally smaller than the out-of-plane perpendicular component of motion. Since the derivation of in-plane and out-of plane depended primarily on the membrane shape, the relative sizes of the predicted motion components did not vary with frequency. PMID:23247058

The Effects of Spall on m(b) and M(s)

DTIC Science & Technology

1978-04-04

HARDHAT 02-15-62 37 116 5.9 287 .12 .44 CHINCHILLA I 02-19-62 37 116 1.8 150 .17 .51 PLATYPUS 02-24-62 37 116 0-20 58 .07 .15 PAMPAS 03-01-62 37 116 0...16 1.78 335 .12 .51 PLATYPUS 15 .05 .86 32 .04 .51 PAMPAS 15 .20 17.02 ERMINE 15 .03 .43 A- 1 APPENDIX Continued Surface Particle Velocity Data

On the self-organization of magnetic field and highly diluted matter in astrophysics

NASA Astrophysics Data System (ADS)

Berdichevsky, D. B.

2015-12-01

It is explored the self organization of matter and field in regions beyond our common reach on the surface of our planet and its atmospheric surroundings. This state of matter, which most basic property, the freezing in the magnetic field, see e.g., Chew et al, 1956, has proved to exist in the regions where robotic observations in the near and far space perform detailed observations of magnetic fields, and extreme dilute plasma (commonly about 1000 to 0.1 or less ionized particles per cubic cm). We present and discuss here simple hypotheses on the nature of what could be this state of magnetized matter which in the electron distribution shows a shape which often can successfully be described with a kappa distribution when inside a strongly magnetized transient, of the magnetic cloud kind, see e.g., Nieves Chinchilla and Figueroa-Viñas, 2008. This work is in many ways an extension of Alfven work on magnetized space plasmas, Alven, 1942. Chew, G.F., M.L., Goldberger, and F.E. Low, 1956, the Royal Soc. London, section Math & Phys Sc., 236, pp. 112. Nieves-Chinchilla, T., and A., Figueroa-Viñas, 2008, J. Geophys. Res., 113, A02105. Alfvén, H (1942). "Existence of electromagnetic-hydrodynamic waves". Nature 150: 405.. doi:10.1038/150405d0

Selective degeneration of a putative cholinergic pathway in the chinchilla cochlea following infusion with ethylcholine aziridinium ion.

PubMed

Morley, B J; Spangler, K M; Schneider, B L; Javel, E

1991-03-22

Ethylcholine aziridinium ion (AF64A) diluted in artificial perilymph, or artificial perilymph alone was infused into the cochlea of chinchillas. After a survival time of 7 days, the cochleas were fixed with aldehydes, post-fixed in osmium and embedded in epoxy resin for light and electron microscopy. The ultrastructure of the cochleas infused with artificial perilymph was normal. Infusion of 1 microM AF64A resulted in massive degeneration of the axons of the lateral efferent system, a putative cholinergic pathway that originates in the brainstem and terminates on dendrites of the spiral ganglion innervating cochlear inner hair cells. The axons and terminals of a second putative cholinergic pathway, the medial efferent system which terminates on the outer hair cells, were normal. Infusion of AF64A in a concentration of 10 microM resulted in significant pathology of cochlear and supporting cells as well as the loss of efferent terminals at both inner and outer hair cell regions. The results suggest that AF64A is a selective neurotoxin when used under low-dosage conditions, and that certain pathways may be more susceptible to the effects of AF64A than others. One interpretation of these findings is that lateral efferent axons may have a higher rate of high-affinity choline uptake than terminals of the medial efferent axons.

Cochlear anatomy using micro computed tomography (μCT) imaging

NASA Astrophysics Data System (ADS)

Kim, Namkeun; Yoon, Yongjin; Steele, Charles; Puria, Sunil

2008-02-01

A novel micro computed tomography (μCT) image processing method was implemented to measure anatomical features of the gerbil and chinchilla cochleas, taking into account the bent modailosis axis. Measurements were made of the scala vestibule (SV) area, the scala tympani (SV) area, and the basilar membrane (BM) width using prepared cadaveric temporal bones. 3-D cochlear structures were obtained from the scanned images using a process described in this study. It was necessary to consider the sharp curvature of mododailosis axis near the basal region. The SV and ST areas were calculated from the μCT reconstructions and compared with existing data obtained by Magnetic Resonance Microscopy (MRM), showing both qualitative and quantitative agreement. In addition to this, the width of the BM, which is the distance between the primary and secondary osseous spiral laminae, is calculated for the two animals and compared with previous data from the MRM method. For the gerbil cochlea, which does not have much cartilage in the osseous spiral lamina, the μCT-based BM width measurements show good agreement with previous data. The chinchilla BM, which contains more cartilage in the osseous spiral lamina than the gerbil, shows a large difference in the BM widths between the μCT and MRM methods. The SV area, ST area, and BM width measurements from this study can be used in building an anatomically based mathematical cochlear model.

Feed-forward and feed-backward amplification model from cochlear cytoarchitecture: an interspecies comparison.

PubMed

Yoon, Yong-Jin; Steele, Charles R; Puria, Sunil

2011-01-05

The high sensitivity and wide bandwidth of mammalian hearing are thought to derive from an active process involving the somatic and hair-bundle motility of the thousands of outer hair cells uniquely found in mammalian cochleae. To better understand this, a biophysical three-dimensional cochlear fluid model was developed for gerbil, chinchilla, cat, and human, featuring an active "push-pull" cochlear amplifier mechanism based on the cytoarchitecture of the organ of Corti and using the time-averaged Lagrangian method. Cochlear responses are simulated and compared with in vivo physiological measurements for the basilar membrane (BM) velocity, V(BM), frequency tuning of the BM vibration, and Q₁₀ values representing the sharpness of the cochlear tuning curves. The V(BM) simulation results for gerbil and chinchilla are consistent with in vivo cochlea measurements. Simulated mechanical tuning curves based on maintaining a constant V(BM) value agree with neural-tuning threshold measurements better than those based on a constant displacement value, which implies that the inner hair cells are more sensitive to V(BM) than to BM displacement. The Q₁₀ values of the V(BM) tuning curve agree well with those of cochlear neurons across species, and appear to be related in part to the width of the basilar membrane. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Coagulating activity of the blood, vascular wall, and myocardium under hypodynamia conditions

NASA Technical Reports Server (NTRS)

Petrovskiy, B. V. (Editor); Chazov, E. I. (Editor); Andreyev, S. V. (Editor)

1980-01-01

In order to study the effects of hypodynamia on the coagulating properties of the blood, vascular wall, and myocardium, chinchilla rabbits were kept for varying periods in special cages which restricted their movements. At the end of the experiment, blood samples were taken and the animals were sacrificed. Preparations were made from the myocardium venae cavae, and layers of the aorta. Two resultant interrelated and mutually conditioned syndromes were discovered: thrombohemorrhagic in the blood and hemorrago-thrombotic in the tissues.

Inheritance of coat colour in the Anatolian shepherd dog.

PubMed

Robinson, R

1989-01-01

The predominant colour of the Anatolian Shepherd dog varies from a dark fawn to light red, with a variable black muzzle and face (mask). Evidence is presented that the colour is due to the dominant yellow allele (Ay) of the agouti locus. Two other frequent colours are white spotting, due to the piebald allele (sp), and the chinchilla allele (ch). Two rarer colours are the agouti wolf-grey wild type (A+) and a light fawn with a blue facial mask, due to the dilution allele (d).

Community Reaction to Impulsive Noise. A Final 10-Year Research Summary. Revised.

DTIC Science & Technology

1985-06-01

Research Council (1931). blas nose vens ocurrd a niht.Statle nd rigt , he P. D. Schomer, "Dlast Noise Prediction Volume 1: Data Bases and Com-blas noie...change is mirrored in a later study of chinchillas taught to respond to a change in a frequently repeated sound." These animals were much more likely to...34frustration." Among nonverbal animals in Skinner boxes, After discarding complaints about obscure noise extinction is often accompanied by overt

Combined use of fibrin tissue adhesive and acellular dermis in dural repair.

PubMed

Shah, Anil R; Pearlman, Aaron N; O'Grady, Kevin M; Bhattacharyya, Tappan K; Toriumi, Dean M

2007-01-01

The management of cerebrospinal fluid (CSF) leaks can be challenging. Acellular dermal grafts derived from human cadavers can be used as a replacement material when autogenous materials are unavailable. Fibrin tissue adhesive (FTA) is a wound support product that has been used for hemostatic and tissue fixation purposes. The combined use of acellular dermis in conjunction with FTA for dural repair remains a subject of study. The aim of this study was to evaluate wound healing and tissue compatibility characteristics of acellular dermal substitute material when used both with and without FTA, for repair of a dural tear in a chinchilla model. Forty-nine chinchillas were included in this randomized case-control study. The squamous portion of the temporal bone was removed to expose the tegmen. A 2 x 2 mm dural defect was removed to create an iatrogenic CSF leak. Then, animals were randomly assigned to one of three treatment groups: group 1, acellular dermis alone; group 2, acellular dermis with FTA; group 3, fibrinogen, acellular dermis, and FTA. Surgical sites were examined grossly at 1- and 2-week intervals. Temporal bones were examined histologically. Grossly, groups 2 and 3 had significantly less visible CSF leak and brain herniation noted at both 1- and 2-week intervals when compared with group 1. Histological results confirmed the gross results showing the best seal in group 2 and 3. Acellular dermis combined with FTA provided superior support compared with acellular dermis alone in repair of induced dural defects.

Sensorineural hearing loss amplifies neural coding of envelope information in the central auditory system of chinchillas

PubMed Central

Zhong, Ziwei; Henry, Kenneth S.; Heinz, Michael G.

2014-01-01

People with sensorineural hearing loss often have substantial difficulty understanding speech under challenging listening conditions. Behavioral studies suggest that reduced sensitivity to the temporal structure of sound may be responsible, but underlying neurophysiological pathologies are incompletely understood. Here, we investigate the effects of noise-induced hearing loss on coding of envelope (ENV) structure in the central auditory system of anesthetized chinchillas. ENV coding was evaluated noninvasively using auditory evoked potentials recorded from the scalp surface in response to sinusoidally amplitude modulated tones with carrier frequencies of 1, 2, 4, and 8 kHz and a modulation frequency of 140 Hz. Stimuli were presented in quiet and in three levels of white background noise. The latency of scalp-recorded ENV responses was consistent with generation in the auditory midbrain. Hearing loss amplified neural coding of ENV at carrier frequencies of 2 kHz and above. This result may reflect enhanced ENV coding from the periphery and/or an increase in the gain of central auditory neurons. In contrast to expectations, hearing loss was not associated with a stronger adverse effect of increasing masker intensity on ENV coding. The exaggerated neural representation of ENV information shown here at the level of the auditory midbrain helps to explain previous findings of enhanced sensitivity to amplitude modulation in people with hearing loss under some conditions. Furthermore, amplified ENV coding may potentially contribute to speech perception problems in people with cochlear hearing loss by acting as a distraction from more salient acoustic cues, particularly in fluctuating backgrounds. PMID:24315815

Hair-cell counts and afferent innervation patterns in the cristae ampullares of the squirrel monkey with a comparison to the chinchilla

NASA Technical Reports Server (NTRS)

Fernandez, C.; Lysakowski, A.; Goldberg, J. M.

1995-01-01

1. The numbers of type I and type II hair cells were estimated by dissector techniques applied to semithin, stained sections of the horizontal, superior, and posterior cristae in the squirrel monkey and the chinchilla. 2. The crista in each species was divided into concentrically arranged central, intermediate, and peripheral zones of equal areas. The three zones can be distinguished by the sizes of individual hair cells and calyx endings, by the density of hair cells, and by the relative frequency of calyx endings innervating single or multiple type I hair cells. 3. In the monkey crista, type I hair cells outnumber type II hair cells by a ratio of almost 3:1. The ratio decreases from 4-5:1 in the central and intermediate zones to under 2:1 in the peripheral zone. For the chinchilla, the ratio is near 1:1 for the entire crista and decreases only slightly between the central and peripheral zones. 4. Nerve fibers supplying the cristae in the squirrel monkey were labeled by extracellular injections of horseradish peroxidase (HRP) into the vestibular nerve. Peripheral terminations of individual fibers were reconstructed and related to the zones of the cristae they innervated and to the sizes of their parent axons. Results were similar for the horizontal, superior, and posterior cristae. 5. Axons seldom bifurcate below the neuroepithelium. Most fibers begin branching shortly after crossing the basement membrane. Their terminal arbors are compact, usually extending no more than 50-100 microns from the parent exon. A small number of long intraepithelial fibers enter the intermediate and peripheral zones of the cristae near its base, then run unbranched for long distances through the neuroepithelium to reach the central zone. 6. There are three classes of afferent fibers innervating the monkey crista. Calyx fibers terminate exclusively on type I hair cells, and bouton fibers end only on type II hair cells. Dimorphic fibers provide a mixed innervation, including calyx endings to type I hair cells and bouton endings to type II hair cells. Long intraepithelial fibers are calyx and dimorphic units, whose terminal fields are similar to those of other fibers. The central zone is innervated by calyx and dimorphic fibers; the peripheral zone, by bouton and dimorphic fibers; and the intermediate zone, by all three kinds of fibers. Internal (axon) diameters are largest for calyx fibers and smallest for bouton fibers. Of the entire sample of 286 labeled fibers, 52% were dimorphic units, 40% were calyx units, and 8% were bouton units.(ABSTRACT TRUNCATED AT 400 WORDS).

Prolonged noise exposure-induced auditory threshold shifts in rats

PubMed Central

Chen, Guang-Di; Decker, Brandon; Muthaiah, Vijaya Prakash Krishnan; Sheppard, Adam; Salvi, Richard

2014-01-01

Noise-induced hearing loss (NIHL) initially increases with exposure duration, but eventually reaches an asymptotic threshold shift (ATS) once the exposure duration exceeds 18-24 h. Equations for predicting the ATS have been developed for several species, but not for rats, even though this species is extensively used in noise exposure research. To fill this void, we exposed rats to narrowband noise (NBN, 16-20 kHz) for 5 weeks starting at 80 dB SPL in the first week and then increasing the level by 6 dB per week to a final level of 104 dB SPL. Auditory brainstem responses (ABR) were recorded before, during, and following the exposure to determine the amount of hearing loss. The noise induced threshold shift to continuous long-term exposure, defined as compound threshold shift (CTS), within and above 16-20 kHz increased with noise level at the rate of 1.82 dB threshold shift per dB of noise level (NL) above a critical level (C) of 77.2 dB SPL i.e. CTS = 1.82(NL-77.2). The normalized amplitude of the largest ABR peak measured at 100 dB SPL decreased at the rate of 3.1% per dB of NL above the critical level of 76.9 dB SPL, i.e., %ABR Reduction = 3.1%(NL-76.9). ABR thresholds measured >30 days post-exposure only partially recovered resulting in a permanent threshold shift of 30-40 dB along with severe hair cell loss in the basal, high-frequency region of the cochlea. In the rat, CTS increases with noise level with a slope similar to humans and chinchillas. The critical level (C) in the rat is similar to that of humans, but higher than that of chinchillas. PMID:25219503

Low-dose D-methionine and N-acetyl-L-cysteine for protection from permanent noise-induced hearing loss in chinchillas.

PubMed

Clifford, Royce E; Coleman, John K M; Balough, Ben J; Liu, Jianzhong; Kopke, Richard D; Jackson, Ronald L

2011-12-01

Despite efforts at public health awareness and stringent industrial standards for hearing protection, noise-induced hearing loss (NIHL) remains a formidable public health concern. Although many antioxidants have proven to be beneficial in the laboratory for prevention of permanent NIHL, low-dose combinations of compounds with different biochemical mechanisms of action may allow long-term administration with fewer side effects and equal efficacy. The mixture of D-methionine and N-acetyl-L-cysteine administered at levels less than 10% of standard dosing has not been previously reported. Twenty-six female adult Chinchilla laniger were placed in 4 study groups, consisting of (1) a group receiving combination 12.5 mg/kg each D-methionine and N-acetyl-L-cysteine (DMET/NAC group), (2) a group receiving 12.5 mg/kg D-methionine (DMET-only group), (3) a group receiving 12.5 mg/kg N-acetyl-L-cysteine (NAC-only group), and (4) saline controls. Laboratory. All groups received twice-daily intraperitoneal injections 2 days prior to noise exposure, 1 hour before and after exposure on day 3, and for 2 days subsequently, totaling 10 doses of 125 mg/kg for each antioxidant over 5 days. Although NAC-only animals paralleled saline control recovery during 3 weeks, the DMET-only group revealed gradual improvement with statistically significant recovery in the middle frequencies. The DMET/NAC group showed significant improvement at most frequencies compared with controls (P < .001 and P < .05). Significant recovery of hearing was observed following continuous noise exposure with either DMET only or a combination of low-dose DMET/NAC, demonstrating a considerably lower dose of antioxidants required than previously reported for hearing recovery following acoustic trauma.

Haemophilus influenzae OxyR: Characterization of Its Regulation, Regulon and Role in Fitness

PubMed Central

Whitby, Paul W.; Morton, Daniel J.; VanWagoner, Timothy M.; Seale, Thomas W.; Cole, Brett K.; Mussa, Huda J.; McGhee, Phillip A.; Bauer, Chee Yoon S.; Springer, Jennifer M.; Stull, Terrence L.

2012-01-01

To prevent damage by reactive oxygen species, many bacteria have evolved rapid detection and response systems, including the OxyR regulon. The OxyR system detects reactive oxygen and coordinates the expression of numerous defensive antioxidants. In many bacterial species the coordinated OxyR-regulated response is crucial for in vivo survival. Regulation of the OxyR regulon of Haemophilus influenzae was examined in vitro, and significant variation in the regulated genes of the OxyR regulon among strains of H. influenzae was observed. Quantitative PCR studies demonstrated a role for the OxyR-regulated peroxiredoxin/glutaredoxin as a mediator of the OxyR response, and also indicated OxyR self-regulation through a negative feedback loop. Analysis of transcript levels in H. influenzae samples derived from an animal model of otitis media demonstrated that the members of the OxyR regulon were actively upregulated within the chinchilla middle ear. H. influenzae mutants lacking the oxyR gene exhibited increased sensitivity to challenge with various peroxides. The impact of mutations in oxyR was assessed in various animal models of H. influenzae disease. In paired comparisons with the corresponding wild-type strains, the oxyR mutants were unaffected in both the chinchilla model of otitis media and an infant model of bacteremia. However, in weanling rats the oxyR mutant was significantly impaired compared to the wild-type strain. In contrast, in all three animal models when infected with a mixture of equal numbers of both wild-type and mutant strains the mutant strain was significantly out competed by the wild-type strain. These findings clearly establish a crucial role for OxyR in bacterial fitness. PMID:23226321

Auditory brainstem responses predict auditory nerve fiber thresholds and frequency selectivity in hearing impaired chinchillas

PubMed Central

Henry, Kenneth S.; Kale, Sushrut; Scheidt, Ryan E.; Heinz, Michael G.

2011-01-01

Non-invasive auditory brainstem responses (ABRs) are commonly used to assess cochlear pathology in both clinical and research environments. In the current study, we evaluated the relationship between ABR characteristics and more direct measures of cochlear function. We recorded ABRs and auditory nerve (AN) single-unit responses in seven chinchillas with noise induced hearing loss. ABRs were recorded for 1–8 kHz tone burst stimuli both before and several weeks after four hours of exposure to a 115 dB SPL, 50 Hz band of noise with a center frequency of 2 kHz. Shifts in ABR characteristics (threshold, wave I amplitude, and wave I latency) following hearing loss were compared to AN-fiber tuning curve properties (threshold and frequency selectivity) in the same animals. As expected, noise exposure generally resulted in an increase in ABR threshold and decrease in wave I amplitude at equal SPL. Wave I amplitude at equal sensation level (SL), however, was similar before and after noise exposure. In addition, noise exposure resulted in decreases in ABR wave I latency at equal SL and, to a lesser extent, at equal SPL. The shifts in ABR characteristics were significantly related to AN-fiber tuning curve properties in the same animal at the same frequency. Larger shifts in ABR thresholds and ABR wave I amplitude at equal SPL were associated with greater AN threshold elevation. Larger reductions in ABR wave I latency at equal SL, on the other hand, were associated with greater loss of AN frequency selectivity. This result is consistent with linear systems theory, which predicts shorter time delays for broader peripheral frequency tuning. Taken together with other studies, our results affirm that ABR thresholds and wave I amplitude provide useful estimates of cochlear sensitivity. Furthermore, comparisons of ABR wave I latency to normative data at the same SL may prove useful for detecting and characterizing loss of cochlear frequency selectivity. PMID:21699970

Repair of Tympanic Membrane Perforations with Customized Bioprinted Ear Grafts Using Chinchilla Models.

PubMed

Kuo, Che-Ying; Wilson, Emmanuel; Fuson, Andrew; Gandhi, Nidhi; Monfaredi, Reza; Jenkins, Audrey; Romero, Maria; Santoro, Marco; Fisher, John P; Cleary, Kevin; Reilly, Brian

2018-03-01

The goal of this work is to develop an innovative method that combines bioprinting and endoscopic imaging to repair tympanic membrane perforations (TMPs). TMPs are a serious health issue because they can lead to both conductive hearing loss and repeated otitis media. TMPs occur in 3-5% of cases after ear tube placement, as well as in cases of acute otitis media (the second most common infection in pediatrics), chronic otitis media with or without cholesteatoma, or as a result of barotrauma to the ear. About 55,000 tympanoplasties, the surgery performed to reconstruct TMPs, are performed every year, and the commonly used cartilage grafting technique has a success rate between 43% and 100%. This wide variability in successful tympanoplasty indicates that the current approach relies heavily on the skill of the surgeon to carve the shield graft into the shape of the TMP, which can be extremely difficult because of the perforation's irregular shape. To this end, we hypothesized that patient specific acellular grafts can be bioprinted to repair TMPs. In vitro data demonstrated that our approach resulted in excellent wound healing responses (e.g., cell invasion and proliferations) using our bioprinted gelatin methacrylate constructs. Based on these results, we then bioprinted customized acellular grafts to treat TMP based on endoscopic imaging of the perforation and demonstrated improved TMP healing in a chinchilla study. These ear graft techniques could transform clinical practice by eliminating the need for hand-carved grafts. To our knowledge, this is the first proof of concept of using bioprinting and endoscopic imaging to fabricate customized grafts to treat tissue perforations. This technology could be transferred to other medical pathologies and be used to rapidly scan internal organs such as intestines for microperforations, brain covering (Dura mater) for determination of sites of potential cerebrospinal fluid leaks, and vascular systems to determine arterial wall damage before aneurysm rupture in strokes.

Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise.

PubMed

Harding, Gary W; Bohne, Barbara A; Lee, Steve C; Salt, Alec N

2007-03-01

Infrasound (i.e., <20 Hz for humans; <100 Hz for chinchillas) is not audible, but exposure to high-levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4 kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24h. For each animal, the tympanic membrane (TM) in one ear was perforated ( approximately 1 mm(2)) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4 kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10-21 dB DPOAE LS from 0.6 to 2 kHz. The infrasound exposure alone resulted in a 10-20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4 kHz OBN alone at 108 dB produced a 10-50 dB ABR TS for 0.5-12 kHz, a 10-60 dB DPOAE LS for 0.6-16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4 kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4 kHz OBN alone. Exposure to only the 4 kHz OBN at 86 dB produces a 10-40 dB ABR TS for 3-12 kHz and 10-30 dB DPOAE LS for 3-8 kHz but little or no OHC loss in the middle of the first turn. No differences were found in the functional and hair-cell losses from exposure to the 4 kHz OBN at 86 dB in the presence or absence of infrasound. We hypothesize that exposure to infrasound and an intense 4 kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound and a moderate 4 kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this moderate level exposure.

Effect of infrasound on cochlear damage from exposure to a 4-kHz octave band of noise

PubMed Central

Harding, Gary W.; Bohne, Barbara A.; Lee, Steve C.; Salt, Alec N.

2008-01-01

Infrasound (i.e., < 20 Hz for humans; < 100 Hz for chinchillas) is not audible, but exposure to high levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4-kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24 h. For each animal, the tympanic membrane (TM) in one ear was perforated (~1 mm2) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4-kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10–21 dB DPOAE LS from 0.6–2 kHz. The infrasound exposure alone resulted in a 10–20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4-kHz OBN alone at 108 dB produced a 10–50 dB ABR TS for 0.5–12 kHz, a 10–60 dB DPOAE LS for 0.6–16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4-kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4-kHz OBN alone. Exposure to only the 4-kHz OBN at 86 dB produces a 10–40 dB ABR TS for 3–12 kHz and 10–30 dB DPOAE LS for 3–8 kHz but little or no OHC loss in the middle of the first turn. No differences were found in the functional and hair-cell losses from exposure to the 4-kHz OBN at 86 dB in the presence or absence of infrasound. We hypothesize that exposure to infrasound and an intense 4-kHz OBN increases cochlear damage because the large fluid movements from infrasound cause more intermixing of cochlear fluids through the damaged reticular lamina. Simultaneous infrasound and a moderate 4-kHz OBN did not increase cochlear damage because the reticular lamina rarely breaks down during this moderate level exposure. PMID:17300889

[Experimental-morphologic study of bone tissue reaction to carbon-containing material implantation with initiated X-ray contrast property].

PubMed

Grigorian, A S; Nabiev, F Kh; Golovin, R V

2005-01-01

In experimental study on 15 rabbits (chinchilla) influence of titanium plates implanted lapped on adjacent tissues in the region of the lower jaw body (comparison group) and carbon material with added boron in the concentrations of 8 and 15% (the study group) was studied. Results of the experimental-morphological investigation show that carbon-based materials with boron addition (with its content 8 and 15%) did not impede adaptive rebuilding of bone tissues and in particular bone structure regeneration in the process of reactive rebuilding of the "maternal" bone. Moreover, as the result of reactive processes developing in osseous tissues after implantation of the tested materials their successful integration in surrounding tissue structures was detected.

Temporal resolution of the Florida manatee (Trichechus manatus latirostris) auditory system.

PubMed

Mann, David A; Colbert, Debborah E; Gaspard, Joseph C; Casper, Brandon M; Cook, Mandy L H; Reep, Roger L; Bauer, Gordon B

2005-10-01

Auditory evoked potential (AEP) measurements of two Florida manatees (Trichechus manatus latirostris) were measured in response to amplitude modulated tones. The AEP measurements showed weak responses to test stimuli from 4 kHz to 40 kHz. The manatee modulation rate transfer function (MRTF) is maximally sensitive to 150 and 600 Hz amplitude modulation (AM) rates. The 600 Hz AM rate is midway between the AM sensitivities of terrestrial mammals (chinchillas, gerbils, and humans) (80-150 Hz) and dolphins (1,000-1,200 Hz). Audiograms estimated from the input-output functions of the EPs greatly underestimate behavioral hearing thresholds measured in two other manatees. This underestimation is probably due to the electrodes being located several centimeters from the brain.

Otoacoustic Estimates of Cochlear Tuning: Testing Predictions in Macaque

NASA Astrophysics Data System (ADS)

Shera, Christopher A.; Bergevin, Christopher; Kalluri, Radha; Mc Laughlin, Myles; Michelet, Pascal; van der Heijden, Marcel; Joris, Philip X.

2011-11-01

Otoacoustic estimates of cochlear frequency selectivity suggest substantially sharper tuning in humans. However, the logic and methodology underlying these estimates remain untested by direct measurements in primates. We report measurements of frequency tuning in macaque monkeys, Old-World primates phylogenetically closer to humans than the small laboratory animals often taken as models of human hearing (e.g., cats, guinea pigs, and chinchillas). We find that measurements of tuning obtained directly from individual nerve fibers and indirectly using otoacoustic emissions both indicate that peripheral frequency selectivity in macaques is significantly sharper than in small laboratory animals, matching that inferred for humans at high frequencies. Our results validate the use of otoacoustic emissions for noninvasive measurement of cochlear tuning and corroborate the finding of sharper tuning in humans.

Modeling OAE responses to short tones

NASA Astrophysics Data System (ADS)

Duifhuis, Hendrikus; Siegel, Jonathan

2015-12-01

In 1999 Shera and Guinan postulated that otoacoustic emissions evoked by low-level transient stimuli are generated by coherent linear reflection (CRF or CLR). This hypothesis was tested experimentally, e.g., by Siegel and Charaziak[10] by measuring emissions evoked by short (1 ms) tone pips in chinchilla. Using techniques in which supplied level and recorded spectral information were used Siegel and Charaziak concluded that much of the emission was generated by a mechanism in a region extending basally from the peak of the traveling wave and that the action of the suppressor is to remove emission generators evoked by the tone-pip and not to generate nonlinear artifacts in regions basal to the peak region. The original formulation of the CRF theory does not account for these results This study addresses relevant cochlear model predictions.

[Experimental study of infrasonic phonophoresis].

PubMed

Filatov, V V

2001-01-01

A new method of drug administration, infrared phonophoresis, was experimentally studied. The method has no analogs in the world. The study was carried out on 20 Chinchilla rabbits. Water applications impregnated with equal volumes of the radiopharmaceutical (RP) were placed into the conjunctival cavities of both eyes. The right eye was control and the left was treated by infrasound (experiment). The information was recorded in live animals after removal of the application and thorough washing of the conjunctival cavity immediately, 30 min, and 1 h after infrasound phonophoresis session. Radioactivity measurements at all terms indicate its stable increase in the experimental eye and a progressive decrease in the control eye. Hence, infrasound promoted long accumulation of the RP in the eye at anterior route of the drug delivery without preliminary injection of the drug into ocular vessels.

Transfection using hydroxyapatite nanoparticles in the inner ear via an intact round window membrane in chinchilla

NASA Astrophysics Data System (ADS)

Wu, Xuewen; Ding, Dalian; Jiang, Haiyan; Xing, Xiaowei; Huang, Suping; Liu, Hong; Chen, Zhedong; Sun, Hong

2012-01-01

Hydroxyapatite nanoparticles (nHAT) are known to have excellent biocompatibility, and have attracted increasing attention as new candidates of non-viral vectors for gene therapy. In our previous studies, nHAT carrying a therapeutic gene and a reporter gene were successfully transfected into the spiral ganglion neurons in the inner ear of guinea pigs in vivo as well as in the cultured cell lines, although the transfection efficiencies were never higher than 30%. In this study, the surface modification of nHAT with polyethylenimine (PEI) was made (PEI-nHAT, diameter = 73.09 ± 27.32 nm) and a recombinant plasmid carrying enhanced green fluorescent protein (EGFP) gene and neurotrophin-3 (NT-3) gene was constructed as pEGFPC2-NT3. The PEI modified nHAT and the recombinant plasmid was then connected to form the nHAT-based vector-gene complex (PEI-nHAT-pEGFPC2-NT3). This complex was then placed onto the intact round window membranes of the chinchillas for inner ear transfection. Auditory brainstem response (ABR) was tested to evaluate auditory function. Green fluorescence of EGFP was observed using confocal microscopy 48 h after administering vector-gene complexes. There was no significant threshold shift in tone burst-evoked ABR at any tested frequency. Abundant, condensed green fluorescence was found in dark cells on both sides of the crista and around the macula of the utricle. Scattered EGFP signals were also detected in vestibular hair cells, some Schwann cells in the cochlear spiral ganglion region, some outer pillar cells in the organ of Corti, and a few cells in the stria vascularis. The density of green fluorescence-marked cells was obviously higher in the vestibular dark cell area than in other areas of the inner ear, suggesting that vestibular dark cells may have the ability to actively engulf the nHAT-based vector-gene complexes. Considering the high transfection efficiency in the vestibular system, PEI-nHAT may be a potential vector for gene therapy of inner ear diseases, especially vestibular disorders, and deserves further study.

Waves on Reissner’s membrane: a mechanism for the propagation of otoacoustic emissions from the cochlea

PubMed Central

Reichenbach, Tobias; Stefanovic, Aleksandra; Nin, Fumiaki; Hudspeth, A. J.

2012-01-01

Summary Sound is detected and converted into electrical signals within the ear. The cochlea not only acts as a passive detector of sound, however, but can also produce tones itself. These otoacoustic emissions are a striking manifestation of the cochlea’s mechanical active process. A controversy remains of how these mechanical signals propagate back to the middle ear, from which they are emitted as sound. Here we combine theoretical and experimental studies to show that mechanical signals can be transmitted by waves on Reissner’s membrane, an elastic structure within the cochea. We develop a theory for wave propagation on Reissner’s membrane and its role in otoacoustic emissions. Employing a scanning laser interferometer, we measure traveling waves on Reissner’s membrane in the gerbil, guinea pig, and chinchilla. The results accord with the theory and thus support a role for Reissner’s membrane in otoacoustic emissions. PMID:22580949

Relationship between cardiovascular system response and adrenocortical glucocorticoid function on exposure to diffuse, low-intensity helium-neon laser emission

NASA Astrophysics Data System (ADS)

Ushkova, I. N.; Pokrovskaya, L. A.; Stepanov, G. S.; Suvorov, I. M.; Kogan, M. Y.; Grishina, Y. F.

1984-06-01

The effect of light from a low intensity helium neon laser on the formation of a series of adaptive processes in the body is investigated. The study is carried out on 32 chinchilla rabbits, weighing from two to two point five kilograms. The right eyes of the creatures were subjected to diffuse laser radiation, for 30 days, 14 minutes per day, under conditions of low illumination. Controls are rabbits under the same conditions, but not exposed to laser radiation. In order to isolate the early glucocorticoid response to the treatment, the hydrocortisone content of the blood is determined which permitted judgment on presence of a functional cumulation effect. The body developed an adaptive/compensatory reaction to the laser radiation so that hydrocortisone levels and the system's hemodynamics and nervous system returned to normal.

Sarcoptic mange infestation in rabbits in an organized farm at Tamil Nadu.

PubMed

Arul Prakash, M; Soundararajan, C; Nagarajan, K; Tensingh Gnanaraj, P; Ramesh Saravanakumar, V

2017-06-01

Sarcoptes scabiei are burrowing mites which causes major constraints in rabbit production. Eighty-eight rabbits were examined for mange infestation at University Research Farm, Tamil Nadu. Overall incidence of mange infestation in rabbit was 23.6 %. On microscopical examination, the mite was identified as Sacoptes scabiei var cuniculi. Among the breeds, Soviet Chinchilla were found to be infested more (57.14 %) followed by New Zealand White (28.57 %) and White Giant (28.57 %). Among the age groups, adults (33.33 %) were heavily infested than the grower (21.88 %) whereas, suckling had no infestation of mange. Among the sex, males (21.95 %) were heavily infested than the females (14.89 %). Lesions were mostly found on the edges of ear, nose, face and legs and characterized by loss of hair, thickening of the skin, irregular dried dirty encrusted scabs with erythema and disfigurement of face and ear.

EFFECT OF FREE RADICALS ON CALCITONIN-GENE-RELATED PEPTIDE MEDIATED VASODILATION.

PubMed

Dekanosidze, M; Saganelidze, K; Mitagvaria, N

2018-01-01

It is known that in some pathological conditions, due to the formation of a large number of free oxygen radicals, the cardiovascular system is severely affected. However, the effect of free radicals on CGRP-mediated vasodilation remains unclear. The aim of this work was to study the effect of free radicals on CGRP-mediated neurogenic vasodilation on preparations of an isolated rabbit lingual artery. The experiments were performed on the lingual artery preparations of 6 rabbits of the Chinchilla breed of both sexes. The contractile-relaxation activity of isolated preparations, both with intact endothelial layer and deendotelized, were studied in isometric mode on a strain-gauge unit using mechanotrons of the 6 MX1C type. Our experiments showed that free radicals can disrupt the reactivity of the vascular wall both in the presence and in the absence of endothelium-dependent relaxation factors and that is might be considered as a main conclusion of this study.

THE EFFECT OF IONIZING RADIATION ON THE ANTITOXIC AND ANTIMICROBIAL IMMUNITY (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emel'yanova, O.V.; Geintse, E.A.

1962-01-01

An attempt was made to clarify the effect of ionizing radiation on the antimlcroblal and the antitoxic immunity of animals after vaccinating them with a still experimental, complex vaccine adsorbed on Al hydroxide. The vaccine contained the antigens of dysentery and typhoid fever bacteria and the anatoxlns of botulin, gas gangrene, and teta nus. The twice vaccinated chinchillas were exposed to a sublethal dose of 600 r of Co/sup 60/ gamma rays during the immunity period, 10 days after the vaccination. It was found that this exposure did not affect the antitoxic immunity. After revaccination, a decrease of the antitoxinmore » content to half of its value was noted in some animals. Irradiation of mice with 450 r of x rays 10 days after the revaccination resulted in a similar reduction of the antimicrobial activity. Thus, previous immunization increased the resistance against harmful radiation effects. (TTT)« less

Explanation of Two Curious Phenomena Regarding the Relationship Between Tectorial Membrane and Basilar Membrane Dynamics

NASA Astrophysics Data System (ADS)

Nobili, R.

2003-02-01

Two years ago, Ruggero et al. [1] focused attention on two curious phenomena regarding the magnitude and phase of tectorial-membrane (TM) vibration relative to basilar-membrane (BM) vibration at a basal site of the chinchilla cochlea: 1) Over a wide range of stimulus frequencies, auditory-nerve responses, which are believed to reflect closely the TM vibration, behave as a linear combination of both BM displacement and velocity. 2) Near threshold, auditory-nerve responses to low-frequency tones are synchronous with peak BM velocity towards scala tympani, but at 80-90 dB SPL and 100-110 dB SPL responses undergo two large phase shifts approaching 180°. Such drastic phase shifts have no counterpart in BM vibrations. Here, it is argued that both these remarkable phenomena have a common origin: the viscoelastic properties of the TM attachment to limbus spiralis.

Slow Temporal Integration Enables Robust Neural Coding and Perception of a Cue to Sound Source Location.

PubMed

Brown, Andrew D; Tollin, Daniel J

2016-09-21

In mammals, localization of sound sources in azimuth depends on sensitivity to interaural differences in sound timing (ITD) and level (ILD). Paradoxically, while typical ILD-sensitive neurons of the auditory brainstem require millisecond synchrony of excitatory and inhibitory inputs for the encoding of ILDs, human and animal behavioral ILD sensitivity is robust to temporal stimulus degradations (e.g., interaural decorrelation due to reverberation), or, in humans, bilateral clinical device processing. Here we demonstrate that behavioral ILD sensitivity is only modestly degraded with even complete decorrelation of left- and right-ear signals, suggesting the existence of a highly integrative ILD-coding mechanism. Correspondingly, we find that a majority of auditory midbrain neurons in the central nucleus of the inferior colliculus (of chinchilla) effectively encode ILDs despite complete decorrelation of left- and right-ear signals. We show that such responses can be accounted for by relatively long windows of bilateral excitatory-inhibitory interaction, which we explicitly measure using trains of narrowband clicks. Neural and behavioral data are compared with the outputs of a simple model of ILD processing with a single free parameter, the duration of excitatory-inhibitory interaction. Behavioral, neural, and modeling data collectively suggest that ILD sensitivity depends on binaural integration of excitation and inhibition within a ≳3 ms temporal window, significantly longer than observed in lower brainstem neurons. This relatively slow integration potentiates a unique role for the ILD system in spatial hearing that may be of particular importance when informative ITD cues are unavailable. In mammalian hearing, interaural differences in the timing (ITD) and level (ILD) of impinging sounds carry critical information about source location. However, natural sounds are often decorrelated between the ears by reverberation and background noise, degrading the fidelity of both ITD and ILD cues. Here we demonstrate that behavioral ILD sensitivity (in humans) and neural ILD sensitivity (in single neurons of the chinchilla auditory midbrain) remain robust under stimulus conditions that render ITD cues undetectable. This result can be explained by "slow" temporal integration arising from several-millisecond-long windows of excitatory-inhibitory interaction evident in midbrain, but not brainstem, neurons. Such integrative coding can account for the preservation of ILD sensitivity despite even extreme temporal degradations in ecological acoustic stimuli. Copyright © 2016 the authors 0270-6474/16/369908-14$15.00/0.

Of mice, moles and guinea pigs: functional morphology of the middle ear in living mammals.

PubMed

Mason, Matthew J

2013-07-01

The middle ear apparatus varies considerably among living mammals. Body size, phylogeny and acoustic environment all play roles in shaping ear structure and function, but experimental studies aimed ultimately at improving our understanding of human hearing can sometimes overlook these important species differences. This review focuses on three groups of mammals, bringing together anatomical, zoological and physiological information in order to highlight unusual features of their middle ears and attempt to interpret their function. "Microtype" ears, found in species such as mice and bats, are associated with high-frequency hearing. The orbicular apophysis, the focus of some recent developmental studies on mouse ears, is characteristic of microtype mallei but is not found in humans or other "freely mobile" species. The apophysis increases ossicular inertia about the anatomical axis of rotation: its adaptive purpose in a high-frequency ear is still not clear. Subterranean mammals have convergently evolved a "freely mobile" ossicular morphology which appears to favour lower-frequency sound transmission. More unusual features found in some of these animals include acoustically coupled middle ear cavities, the loss of middle ear muscles and hypertrophied ossicles which are believed to subserve a form of inertial bone conduction. Middle ears of the rodent group Ctenohystrica (which includes guinea pigs and chinchillas, important models in hearing research) show some striking characteristics which together comprise a unique type of auditory apparatus requiring a classification of its own, referred to here as the "Ctenohystrica type". These characteristics include a distinctive malleus morphology, fusion of the malleus and incus, reduction or loss of the stapedius muscle, a synovial stapedio-vestibular articulation and, in chinchillas, enormously expanded middle ear cavities. These characteristics may be functionally linked and associated with the excellent low-frequency hearing found in these animals. The application of new experimental and imaging data into increasingly sophisticated models continues to improve our understanding of middle ear function. However, a more rigorous comparative approach and a better appreciation of the complex patterns of convergent and divergent evolution reflected in the middle ear structures of living mammals are also needed, in order to put findings from different species into the appropriate context. This article is part of a special issue entitled "MEMRO 2012". Copyright © 2012 Elsevier B.V. All rights reserved.

The vestibular nerve of the chinchilla. III. Peripheral innervation patterns in the utricular macula

NASA Technical Reports Server (NTRS)

Fernandez, C.; Goldberg, J. M.; Baird, R. A.

1990-01-01

1. Nerve fibers supplying the utricular macula of the chinchilla were labeled by extracellular injection of horseradish peroxidase into the vestibular nerve. The peripheral terminations of individual fibers were reconstructed and related to the regions of the end organ they innervated and to the sizes of their parent axons. 2. The macula is divided into medial and lateral parts by the striola, a narrow zone that runs for almost the entire length of the sensory epithelium. The striola can be distinguished from the extrastriolar regions to either side of it by the wider spacing of its hair cells. Calyx endings in the striola have especially thick walls, and, unlike similar endings in the extrastriola, many of them innervate more than one hair cell. The striola occupies 10% of the sensory epithelium; the lateral extrastriola, 50%; and the medial extrastriola, 40%. 3. The utricular nerve penetrates the bony labyrinth anterior to the end organ. Axons reaching the anterior part of the sensory epithelium run directly through the connective tissue stroma. Those supplying more posterior regions first enter a fiber layer located at the bottom of the stroma. Approximately one-third of the axons bifurcate below the epithelium, usually within 5-20 microns of the basement membrane. Bifurcations are more common in fibers destined for the extrastriola than for the striola. 4. Both calyx and bouton endings were labeled. Calyces can be simple or complex. Simple calyces innervate individual hair cells, whereas complex calyces supply 2-4 adjacent hair cells. Complex endings are more heavily concentrated in the striola than in the extrastriola. Simple calyces and boutons are found in all parts of the epithelium. Calyces emerge from the parent axon or one of its thick branches. Boutons, whether en passant or terminal, are located on thin collaterals. 5. Fibers can be classified into calyx, bouton, or dimorphic categories. The first type only has calyx endings; the second, only bouton endings; and the third, both kinds of endings. Calyx units make up 6% of the labeled fibers, bouton units less than 2%, and dimorphic units greater than 92%. The three fiber types differ in the macular zones they supply and in the diameters of their parent axons. Calyx units were restricted to the striola. The few bouton units were found in the extrastriola.(ABSTRACT TRUNCATED AT 400 WORDS).

Study of the neovascularisation of prefabrication of flaps using a silicone sheet and an isolated arterial pedicle: experimental study in rabbits.

PubMed

Nguyen, The Hoang; Kloeppel, Marcus; Staudenmaier, Rainer; Werner, Jürgen; Biemer, Edgar

2005-01-01

Use of an isolated artery as an implanted pedicle in prefabricated flaps has rarely been reported either clinically or experimentally. In Chinchilla Bastard rabbits (n = 36), we dissected an isolated arterial pedicle from the femoral and saphenous artery, anastomosed it end-to-end to the femoral vein at the inguinal ligament and created an isolated arterial loop pedicle. This was implanted and fixed with polyglactin 9/0 under a random-pattern vascularised abdominal fasciocutaneous flap. The neovascularisation in the prefabricated flaps was evaluated macroscopically, by blood analysis, selective microangiography, and histology. The results showed a progressive degree of neovascularisation that corresponded to the increasing length of time that the pedicle was implanted in the flaps. Twenty days after prefabrication, the abdominal fasciocutaneous flap was readily perfused by the blood supply from the arterial pedicle. The capacity of the vessels in this group as seen on angiograms had increased to 258 vessels (108%) compared with the control group (239 vessels, 100%).

Intracochlear pressure measurements to study bone conduction transmission: State-of-the art and proof of concept of the experimental Procedure

NASA Astrophysics Data System (ADS)

Borgers, Charlotte; van Wieringen, Astrid; D'hondt, Christiane; Verhaert, Nicolas

2018-05-01

The cochlea is the main contributor in bone conduction perception. Measurements of differential pressure in the cochlea give a good estimation of the cochlear input provided by bone conduction stimulation. Recent studies have proven the feasibility of intracochlear pressure measurements in chinchillas and in human temporal bones to study bone conduction. However, similar measurements in fresh-frozen whole human cadaveric heads could give a more realistic representation of the five different transmission pathways of bone conduction to the cochlea compared to human temporal bones. The aim of our study is to develop and validate a framework for intracochlear pressure measurements to evaluate different aspects of bone conduction in whole human cadaveric heads. A proof of concept describing our experimental setup is provided together with the procedure. Additionally, we also present a method to fix the stapes footplate in order to simulate otosclerosis in human temporal bones. The effectiveness of this method is verified by some preliminary results.

A biphasic epigenetic switch controls immunoevasion, virulence and niche adaptation in non-typeable Haemophilus influenzae.

PubMed

Atack, John M; Srikhanta, Yogitha N; Fox, Kate L; Jurcisek, Joseph A; Brockman, Kenneth L; Clark, Tyson A; Boitano, Matthew; Power, Peter M; Jen, Freda E-C; McEwan, Alastair G; Grimmond, Sean M; Smith, Arnold L; Barenkamp, Stephen J; Korlach, Jonas; Bakaletz, Lauren O; Jennings, Michael P

2015-07-28

Non-typeable Haemophilus influenzae contains an N(6)-adenine DNA-methyltransferase (ModA) that is subject to phase-variable expression (random ON/OFF switching). Five modA alleles, modA2, modA4, modA5, modA9 and modA10, account for over two-thirds of clinical otitis media isolates surveyed. Here, we use single molecule, real-time (SMRT) methylome analysis to identify the DNA-recognition motifs for all five of these modA alleles. Phase variation of these alleles regulates multiple proteins including vaccine candidates, and key virulence phenotypes such as antibiotic resistance (modA2, modA5, modA10), biofilm formation (modA2) and immunoevasion (modA4). Analyses of a modA2 strain in the chinchilla model of otitis media show a clear selection for ON switching of modA2 in the middle ear. Our results indicate that a biphasic epigenetic switch can control bacterial virulence, immunoevasion and niche adaptation in an animal model system.

Global Development of Commercial Underground Coal Gasification

NASA Astrophysics Data System (ADS)

Blinderman, M. S.

2017-07-01

Global development of Underground Coal Gasification (UCG) is considered here in light of latest trends of energy markets and environmental regulations in the countries that have been traditional proponents of UCG. The latest period of UCG development triggered by initial success of the Chinchilla UCG project (1997-2006) has been characterized by preponderance of privately and share-market funded developments. The deceleration of UCG commercialization has been in part caused by recent significant decrease of world oil, gas and coal prices. Another substantial factor was lack of necessary regulations governing extraction and conversion of coal by UCG method in the jurisdictions where the UCG projects were proposed and developed. Along with these objective causes there seem to have been more subjective and technical reasons for a slowdown or cancelation of several significant UCG projects, including low efficiency, poor environmental performance, and inability to demonstrate technology at a sufficient scale and/or at a competitive cost. Latest proposals for UCG projects are briefly reviewed.

[Experimental realization of minimally invasive techniques of scleral collagen cross-linking].

PubMed

Iomdina, Е N; Tarutta, Е P; Semchishen, V А; Korigodskiy, А R; Zakharov, I D; Khoroshilova-Maslova, I P; Ignat'eva, N Yu; Kiseleva, Т N; Sianosyan, А А; Milash, S V

To realize two minimally invasive techniques of scleral collagen cross-linking (SXL) at the equator and posterior pole of the eye: 1) targeted irradiation of the region with ultraviolet A (UVA) and 2) sub-Tenon injection of Sklerateks. To perform UVA-SXL, a tool was developed that includes a UV-LED light source (370 nm, 3 mW/cm2) and a polymer-coated silica multimode optical fiber located in one of the two channels of a detachable metal tip. The other channel is used to deliver riboflavin to the scleral surface. The study included 8 Chinchillas' eyes. Intact fellow eyes served as the controls. Scleral echodensity was measured in vivo with Voluson 730 Pro (Kretz) prior to the procedure and then 2 days and 1 month after. After enucleation, the elastic modulus and the degree of scleral cross-linking were established at the same time-points. A placebo-controlled study on the safety and effectiveness of sub-Tenon Sklerateks injections (solution of amino acid salts in the form of succinates) was conducted on 47 Chinchilla rabbits (94 eyes). Sklerateks or placebo (0.1 ml) was injected below the Tenon's capsule of either eye once a week for 1 month (4 injections; 1st series) or 3 months (12 injections; 2nd series). After the end of the course, 22 eyes were studied morphologically. In 72 eyes, scleral samples were obtained in order to evaluate the elastic modulus (Autograph AGS-H tester, SHIMADZU, Japan) and the rate of cross-linking (judging from the denaturation temperature) by differential scanning calorimetry (Phoenix DSC 204 calorimeter, Netzsch, Germany). After UVA irradiation, the scleral echodensity increased from 86.7±5.1 to 98±4.9 dB. The elastic modulus appeared 1.5 times higher than that of the control samples. The denaturation temperature also increased indicating the rate of scleral cross-linking as high as 15-18%. Weekly Sklerateks for 1-3 months has been shown to induce neither clinical, nor morphological signs of local irritative, damaging, or toxic effect. The findings also include: a 1.8 times higher rate of scleral cross-linking, activation of cellular elements, neoformation of connective tissue on the scleral surface, and vascular growth, which together indicate a pronounced metabolic and strengthening effect of Sklerateks on the sclera. Experimental results on minimally invasive techniques of SXL allow to recommend them for further clinical investigation as a promising treatment of progressive myopia.

No effect of prolonged pulsed high frequency ultrasound imaging of the basilar membrane on cochlear function or hair cell survival found in an initial study.

PubMed

Landry, Thomas G; Bance, Manohar L; Adamson, Robert B; Brown, Jeremy A

2018-06-01

Miniature high frequency ultrasound devices show promise as tools for clinical middle ear and basal cochlea imaging and vibrometry. However, before clinical use it is important to verify that the ultrasound exposure does not damage the cochlea. In this initial study, electrophysiological responses of the cochlea were measured for a range of stimulus frequencies in both ears of anesthetized chinchillas, before and after exposing the organ of Corti region of one ear to pulsed focused ultrasound for 30 min. Measurements were again taken after an 11 day survival period. Cochlear tissue was examined with a confocal microscope for signs of damage to the cochlear hair cells. No significant change in response thresholds due to exposure was found, and no signs of ultrasound-induced tissue damage were observed, although one animal (out of ten) did have a region of extensive tissue damage in the exposed cochlea. However, after further analysis this was concluded to be not likely a result of the ultrasound exposure. Copyright © 2017 Elsevier B.V. All rights reserved.

Iterated intracochlear reflection shapes the envelopes of basilar-membrane click responses

PubMed Central

Shera, Christopher A.

2015-01-01

Multiple internal reflection of cochlear traveling waves has been argued to provide a plausible explanation for the waxing and waning and other temporal structures often exhibited by the envelopes of basilar-membrane (BM) and auditory-nerve responses to acoustic clicks. However, a recent theoretical analysis of a BM click response measured in chinchilla concludes that the waveform cannot have arisen via any equal, repetitive process, such as iterated intracochlear reflection [Wit and Bell (2015), J. Acoust. Soc. Am. 138, 94–96]. Reanalysis of the waveform contradicts this conclusion. The measured BM click response is used to derive the frequency-domain transfer function characterizing every iteration of the loop. The selfsame transfer function that yields waxing and waning of the BM click response also captures the spectral features of ear-canal stimulus-frequency otoacoustic emissions measured in the same animal, consistent with the predictions of multiple internal reflection. Small shifts in transfer-function phase simulate results at different measurement locations and reproduce the heterogeneity of BM click response envelopes observed experimentally. PMID:26723327

[The quantitative changes of bioelements (Ca, Zn, Mg, Cu, Mn) in crystalline lenses under the influence of hypodynamic stress and zinc].

PubMed

Kusleika, Saulius

2002-01-01

The aim of the study was to investigate and estimate quantitative changes of bioelements (Ca, Zn, Mg, Cu, Mn) in the lenses on the influence of hypodynamic stress and zinc (Zn). Hypodynamic stress of 48 days duration was provoked for Chinchilla rabbits (n = 20) by placing them in metal hutches. Every day (48 days) 10 rabbits, which had intervention received 0.3 mg/kg body wt. doses of Zn (in form of Zn acetate). The rabbits (n = 10) of the control group, which had no intervention were kept in vivarium conditions. Concentration of bioelements in the lenses of rabbits was detected by atomic absorption spectrophotometry 503 "Perkin-Elmer" (USA). The investigation revealed that hypodynamic stress of 48 days duration caused the increase in amount of Ca, Zn, Mn in lenses as compared with that in control rabbits and in rabbits receiving Zn. The concentration of bioelements (Ca, Zn, Mg, Cu, Mn) in lenses of rabbits receiving Zn in case of hypodynamic stress did not change significantly.

Protective effect of basic fibroblast growth factor on laser induced retinopathy

PubMed Central

Kartal, Unal; Koptagel, Emel; Bulut, H. Eray; Erdogan, Haydar

2013-01-01

AIM To investigate the side effects of the commonly used laser treatment along with testing the neuroprotective effect of bFGF on a potential retinal impairment. METHODS To do this, 30 chinchilla pigmented adult male rabbits were divided into the control and experimental groups. The control and experimental groups underwent both laser application and bFGF treatment. The retinal tissue impairment and its renewal rate were tested under the light and electron microscopical levels. RESULTS The focal laser application on rabbit eyes caused morphological alterations both in the application region and in the neighbouring areas. In the damaged areas, the outer nuclear layer of the neural retina was almost disappeared, retina pigment epithelium was interrupted, the retina pigment epithelium migrated intraretinally, and the damaged region along with neighbouring areas seemed to be not separated. bFGF application just after the laser photocoagulation, revealed better results in application areas. CONCLUSION It could be suggested that the bFGF application following laser photocoagulation might have protective, repairing and wound healing effects on the retina. PMID:24392319

Basilar-membrane responses to broadband noise modeled using linear filters with rational transfer functions.

PubMed

Recio-Spinoso, Alberto; Fan, Yun-Hui; Ruggero, Mario A

2011-05-01

Basilar-membrane responses to white Gaussian noise were recorded using laser velocimetry at basal sites of the chinchilla cochlea with characteristic frequencies near 10 kHz and first-order Wiener kernels were computed by cross correlation of the stimuli and the responses. The presence or absence of minimum-phase behavior was explored by fitting the kernels with discrete linear filters with rational transfer functions. Excellent fits to the kernels were obtained with filters with transfer functions including zeroes located outside the unit circle, implying nonminimum-phase behavior. These filters accurately predicted basilar-membrane responses to other noise stimuli presented at the same level as the stimulus for the kernel computation. Fits with all-pole and other minimum-phase discrete filters were inferior to fits with nonminimum-phase filters. Minimum-phase functions predicted from the amplitude functions of the Wiener kernels by Hilbert transforms were different from the measured phase curves. These results, which suggest that basilar-membrane responses do not have the minimum-phase property, challenge the validity of models of cochlear processing, which incorporate minimum-phase behavior. © 2011 IEEE

System identification of perilymphatic fistula in an animal model

NASA Technical Reports Server (NTRS)

Wall, C. 3rd; Casselbrant, M. L.

1992-01-01

An acute animal model has been developed in the chinchilla for the study of perilymphatic fistulas. Micropunctures were made in three sites to simulate bony, round window, and oval window fistulas. The eye movements in response to pressure applied to the external auditory canal were recorded after micropuncture induction and in preoperative controls. The main pressure stimulus was a pseudorandom binary sequence (PRBS) that rapidly changed between plus and minus 200 mm of water. The PRBS stimulus, with its wide frequency bandwidth, produced responses clearly above the preoperative baseline in 78 percent of the runs. The response was better between 0.5 and 3.3 Hz than it was below 0.5 Hz. The direction of horizontal eye movement was toward the side of the fistula with positive pressure applied in 92 percent of the runs. Vertical eye movements were also observed. The ratio of vertical eye displacement to horizontal eye displacement depended upon the site of the micropuncture induction. Thus, such a ratio measurement may be clinically useful in the noninvasive localization of perilymphatic fistulas in humans.

Protective effect of basic fibroblast growth factor on retinal injury induced by argon laser photocoagulation

NASA Astrophysics Data System (ADS)

Chen, P.; Zhang, C. P.; San, Q.; Wang, C. Z.; Yang, Z. F.; Kang, H. X.; Qian, H. W.

2010-12-01

Laser photocoagulation treatment is often complicated by a side effect of visual impairment, which is caused by the unavoidable laser-induced retinal destruction. At present no specific is found to cure this retinopathy. The aim of this study was to observe the neuroprotective effect of bFGF on laser-induced retinal injury. Chinchilla rabbits were divided into three groups and argon laser lesions were created in the retinas. Then bFGF or dexamethasone, a widely used ophthalmic preparation, or saline was given severally by retrobulbar injection. The retinal lesions were evaluated histologically and morphometrically, and visual function was examined by ERG. The results showed that bFGF administration better preserved morphology of retinal photoreceptors and significantly diminished the area of the lesions. Furthermore, bFGF promoted the restoration of the ERG b-wave amplitude. In rabbits treated with dexamethasone, however, the lesions showed almost no ameliorative changes. This is the first study to investigate the potential role of bFGF as a remedial agent in laser photocoagulation treatment. These findings suggest that bFGF has significant neuroprotective properties in the retina and this type of neuroprotection may be of clinical significance in reducing iatrogenic laser-induced retinal injuries in humans.

Host-to-host variation of ecological interactions in polymicrobial infections

NASA Astrophysics Data System (ADS)

Mukherjee, Sayak; Weimer, Kristin E.; Seok, Sang-Cheol; Ray, Will C.; Jayaprakash, C.; Vieland, Veronica J.; Swords, W. Edward; Das, Jayajit

2015-02-01

Host-to-host variability with respect to interactions between microorganisms and multicellular hosts are commonly observed in infection and in homeostasis. However, the majority of mechanistic models used to analyze host-microorganism relationships, as well as most of the ecological theories proposed to explain coevolution of hosts and microbes, are based on averages across a host population. By assuming that observed variations are random and independent, these models overlook the role of differences between hosts. Here, we analyze mechanisms underlying host-to-host variations of bacterial infection kinetics, using the well characterized experimental infection model of polymicrobial otitis media (OM) in chinchillas, in combination with population dynamic models and a maximum entropy (MaxEnt) based inference scheme. We find that the nature of the interactions between bacterial species critically regulates host-to-host variations in these interactions. Surprisingly, seemingly unrelated phenomena, such as the efficiency of individual bacterial species in utilizing nutrients for growth, and the microbe-specific host immune response, can become interdependent in a host population. The latter finding suggests a potential mechanism that could lead to selection of specific strains of bacterial species during the coevolution of the host immune response and the bacterial species.

Antigen dose and strain variation as factors in the genetic control of the immune response to sperm whale myoglobin.

PubMed Central

Young, C R; Ebringer, A; Archer, J R

1978-01-01

The primary and secondary immune response to the antigen sperm whale myoglobin was investigated in DBA/2, 129 and B10.BR mice over a dose range of immunization from 10 to 2000 microgram. Using an antigen excess technique, the quantity of antibody produced after secondary immunization followed a sigmoidal dose-response curve and the maximal plateau level was found to be different for each strain of mice. Furthermore, the genetic control of the immune response was investigated in twelve different inbred strains of mice following secondary immunization with 500 microgram of myoglobin. A continuous distribution for the mean antibody responses was obtained for the twelve different strains of mice. High responsiveness was associated with H-2 haplotypes d, f and k located on chromosome 17, the non-agouti gene 'a' located on chromosome 2 and the chinchilla gene 'c(ch)' located on chromosome 7. It is concluded that either a large number of IR-genes to myoglobin are present in many loci located on different chromosomes or the antibody differences could be explained by a cross-tolerance mechanism requiring no IR-genes at all. PMID:417022

The value of a kurtosis metric in estimating the hazard to hearing of complex industrial noise exposures.

PubMed

Qiu, Wei; Hamernik, Roger P; Davis, Robert I

2013-05-01

A series of Gaussian and non-Gaussian equal energy noise exposures were designed with the objective of establishing the extent to which the kurtosis statistic could be used to grade the severity of noise trauma produced by the exposures. Here, 225 chinchillas distributed in 29 groups, with 6 to 8 animals per group, were exposed at 97 dB SPL. The equal energy exposures were presented either continuously for 5 d or on an interrupted schedule for 19 d. The non-Gaussian noises all differed in the level of the kurtosis statistic or in the temporal structure of the noise, where the latter was defined by different peak, interval, and duration histograms of the impact noise transients embedded in the noise signal. Noise-induced trauma was estimated from auditory evoked potential hearing thresholds and surface preparation histology that quantified sensory cell loss. Results indicated that the equal energy hypothesis is a valid unifying principle for estimating the consequences of an exposure if and only if the equivalent energy exposures had the same kurtosis. Furthermore, for the same level of kurtosis the detailed temporal structure of an exposure does not have a strong effect on trauma.

Coinfection with Haemophilus influenzae promotes pneumococcal biofilm formation during experimental otitis media and impedes the progression of pneumococcal disease.

PubMed

Weimer, Kristin E D; Armbruster, Chelsie E; Juneau, Richard A; Hong, Wenzhou; Pang, Bing; Swords, W Edward

2010-10-01

Otitis media is an extremely common pediatric infection and is mostly caused by bacteria that are carried within the nasopharyngeal microbiota. It is clear that most otitis media cases involve simultaneous infection with multiple agents. Chinchillas were infected with nontypeable Haemophilus influenzae, Streptococcus pneumoniae, or a combination of both organisms, and the course of disease was compared. In vitro experiments were also performed to address how coinfection impacts biofilm formation. The incidence of systemic disease was reduced in coinfected animals, compared with those infected with pneumococcus alone. Pneumococci were present within surface-attached biofilms in coinfected animals, and a greater proportion of translucent colony type was observed in the coinfected animals. Because this colony type has been associated with pneumococcal biofilms, the impact of coinfection on pneumococcal biofilm formation was investigated. The results clearly show enhanced biofilm formation in vitro by pneumococci in the presence of H. influenzae. Based on these data, we conclude that coinfection with H. influenzae facilitates pneumococcal biofilm formation and persistence on the middle ear mucosal surface. This enhanced biofilm persistence correlates with delayed emergence of opaque colony variants within the bacterial population and a resulting decrease in systemic infection.

Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae

PubMed Central

Murrah, Kyle A.; Pang, Bing; Richardson, Stephen; Perez, Antonia; Reimche, Jennifer; King, Lauren; Wren, John; Swords, W. Edward

2014-01-01

Streptococcus pneumoniae strains lacking capsular polysaccharide have been increasingly reported in carriage and disease contexts. Since most cases of otitis media involve more than one bacterial species, we aimed to determine the capacity of a nonencapsulated S. pneumoniae clinical isolate to induce disease in the context of a single-species infection and as a polymicrobial infection with nontypeable Haemophilus influenzae. Using the chinchilla model of otitis media, we found that nonencapsulated S. pneumoniae colonizes the nasopharynx following intranasal inoculation, but does not readily ascend into the middle ear. However, when we inoculated nonencapsulated S. pneumoniae directly into the middle ear, the bacteria persisted for two weeks post-inoculation and induced symptoms consistent with chronic otitis media. During coinfection with nontypeable H. influenzae, both species persisted for one week and induced polymicrobial otitis media. We also observed that nontypeable H. influenzae conferred passive protection from killing by amoxicillin upon S. pneumoniae from within polymicrobial biofilms in vitro. Therefore, based on these results, we conclude that nonencapsulated pneumococci are a potential causative agent of chronic/recurrent otitis media, and can also cause mutualistic infection with other opportunists, which could complicate treatment outcomes. PMID:26014114

Emission of sound from the mammalian inner ear

NASA Astrophysics Data System (ADS)

Reichenbach, Tobias; Stefanovic, Aleksandra; Nin, Fumiaki; Hudspeth, A. J.

2013-03-01

The mammalian inner ear, or cochlea, not only acts as a detector of sound but can also produce tones itself. These otoacoustic emissions are a striking manifestation of the mechanical active process that sensitizes the cochlea and sharpens its frequency discrimination. It remains uncertain how these signals propagate back to the middle ear, from which they are emitted as sound. Although reverse propagation might occur through waves on the cochlear basilar membrane, experiments suggest the existence of a second component in otoacoustic emissions. We have combined theoretical and experimental studies to show that mechanical signals can also be transmitted by waves on Reissner's membrane, a second elastic structure within the cochea. We have developed a theoretical description of wave propagation on the parallel Reissner's and basilar membranes and its role in the emission of distortion products. By scanning laser interferometry we have measured traveling waves on Reissner's membrane in the gerbil, guinea pig, and chinchilla. The results accord with the theory and thus support a role for Reissner's membrane in otoacoustic emission. T. R. holds a Career Award at the Scientific Interface from the Burroughs Wellcome Fund; A. J. H. is an Investigator of Howard Hughes Medical Institute.

Behavioral profiles of feline breeds in Japan.

PubMed

Takeuchi, Yukari; Mori, Yuji

2009-08-01

To clarify the behavioral profiles of 9 feline purebreds, 2 Persian subbreeds and the Japanese domestic cat, a questionnaire survey was distributed to 67 small-animal veterinarians. We found significant differences among breeds in all behavioral traits examined except for "inappropriate elimination". In addition, sexual differences were observed in certain behaviors, including "aggression toward cats", "general activity", "novelty-seeking", and "excitability". These behaviors were more common in males than females, whereas "nervousness" and "inappropriate elimination" were rated higher in females. When all breeds were categorized into four groups on the basis of a cluster analysis using the scores of two behavioral trait factors called "aggressiveness/sensitivity" and "vivaciousness", the group including Abyssinian, Russian Blue, Somali, Siamese, and Chinchilla breeds showed high aggressiveness/sensitivity and low vivaciousness. In contrast, the group including the American Shorthair and Japanese domestic cat displayed low aggressiveness/sensitivity and high vivaciousness, and the Himalayan and Persian group showed mild aggressiveness/sensitivity and very low vivaciousness. Finally, the group containing Maine Coon, Ragdoll, and Scottish Fold breeds displayed very low aggressiveness/sensitivity and low vivaciousness. The present results demonstrate that some feline behavioral traits vary by breed and/or sex.

A Multi-channel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3D Vestibular Sensation

PubMed Central

Della Santina, Charles C.; Migliaccio, Americo A.; Patel, Amit H.

2009-01-01

Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode’s targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior. PMID:17554821

The effect of the inner-hair-cell mediated transduction on the shape of neural tuning curves

NASA Astrophysics Data System (ADS)

Altoè, Alessandro; Pulkki, Ville; Verhulst, Sarah

2018-05-01

The inner hair cells of the mammalian cochlea transform the vibrations of their stereocilia into releases of neurotransmitter at the ribbon synapses, thereby controlling the activity of the afferent auditory fibers. The mechanical-to-neural transduction is a highly nonlinear process and it introduces differences between the frequency-tuning of the stereocilia and that of the afferent fibers. Using a computational model of the inner hair cell that is based on in vitro data, we estimated that smaller vibrations of the stereocilia are necessary to drive the afferent fibers above threshold at low (≤0.5 kHz) than at high (≥4 kHz) driving frequencies. In the base of the cochlea, the transduction process affects the low-frequency tails of neural tuning curves. In particular, it introduces differences between the frequency-tuning of the stereocilia and that of the auditory fibers resembling those between basilar membrane velocity and auditory fibers tuning curves in the chinchilla base. For units with a characteristic frequency between 1 and 4 kHz, the transduction process yields shallower neural than stereocilia tuning curves as the characteristic frequency decreases. This study proposes that transduction contributes to the progressive broadening of neural tuning curves from the base to the apex.

Influence of Silicone Sheets on Microvascular Anastomosis

PubMed Central

Kloeppel, Marcus; Hoehnke, Christoph; Staudenmaier, Rainer

2008-01-01

The use of silicone products combined with free flap transfer is well established in reconstructive surgery. We determined the risk of thrombosis as a result of direct contact between the silicone sheet and the point of microanastomosis. We performed microvascular surgery in 24 female Chinchilla Bastard rabbits weighing 3500 to 4000 g using two groups: Group 1 (n = 12), microanastomosis directly in contact with silicone sheets; and Group 2 (n = 12), microanastomosis protected by a 2 × 3 × 1-cm muscle cuff before being placed in contact with the silicone. We assessed flow-through of the microanastomosis by selective microangiography and histology at 1 and 3 weeks. All microanastomoses in Group 1 were occluded by postoperative thromboses, whereas all microanastomoses in Group 2 had adequate flow-through. Histologic analysis revealed thromboses in Group 1 formed from collagenous bundles of fiber securely attached to the intraluminal wall of the vessel. Three weeks after the procedure, these thromboses were canalized by varying small vessels. In Group 2, a slight luminal stenosis with evidence of infiltration of inflammatory cells at the microanastomosis line was observed histologically in all cases. Prefabricated flaps using silicone sheets and muscular cuffs placed around the anastomoses appear to reduce the risk of thrombosis and enhance neovascularization. PMID:18636304

Influence of silicone sheets on microvascular anastomosis.

PubMed

Hoang Nguyen, The; Kloeppel, Marcus; Hoehnke, Christoph; Staudenmaier, Rainer

2008-12-01

The use of silicone products combined with free flap transfer is well established in reconstructive surgery. We determined the risk of thrombosis as a result of direct contact between the silicone sheet and the point of microanastomosis. We performed microvascular surgery in 24 female Chinchilla Bastard rabbits weighing 3500 to 4000 g using two groups: Group 1 (n = 12), microanastomosis directly in contact with silicone sheets; and Group 2 (n = 12), microanastomosis protected by a 2 x 3 x 1-cm muscle cuff before being placed in contact with the silicone. We assessed flow-through of the microanastomosis by selective microangiography and histology at 1 and 3 weeks. All microanastomoses in Group 1 were occluded by postoperative thromboses, whereas all microanastomoses in Group 2 had adequate flow-through. Histologic analysis revealed thromboses in Group 1 formed from collagenous bundles of fiber securely attached to the intraluminal wall of the vessel. Three weeks after the procedure, these thromboses were canalized by varying small vessels. In Group 2, a slight luminal stenosis with evidence of infiltration of inflammatory cells at the microanastomosis line was observed histologically in all cases. Prefabricated flaps using silicone sheets and muscular cuffs placed around the anastomoses appear to reduce the risk of thrombosis and enhance neovascularization.

Penicillin treatment accelerates middle ear inflammation in experimental pneumococcal otitis media.

PubMed Central

Kawana, M; Kawana, C; Giebink, G S

1992-01-01

Most Streptococcus pneumoniae strains are killed by very low concentrations of penicillin and other beta-lactam antibiotics, yet middle ear inflammation and effusion persist for days to weeks after treatment in most cases of pneumococcal otitis media. To study the effect of beta-lactam antibiotic treatment on pneumococci and the middle ear inflammatory response during pneumococcal otitis media, we measured concentrations of pneumococci, inflammatory cells, and lysozyme in middle ear fluid (MEF) by using the chinchilla model. Procaine penicillin G given intramuscularly 12 and 36 h after inoculation of pneumococci into the middle ear caused a significant acceleration in the MEF inflammatory cell concentration compared with that in untreated controls, with a significant peak in the inflammatory cell concentration 24 h after pneumococcal inoculation. The lysozyme concentration in MEF also increased more rapidly in treated than in control animals. Viable pneumococci were not detected in MEF after the second dose of penicillin, but the total pneumococcal cell concentration remained unchanged for at least 45 days. Therefore, penicillin treatment accelerated middle ear inflammation while killing pneumococci, but treatment did not accelerate clearance of the nonviable pneumococcal cells from MEF. Further studies will need to define the contribution of these responses to acute and chronic tissue injury. PMID:1563782

Hypothyroidism Affects Vascularization and Promotes Immune Cells Infiltration into Pancreatic Islets of Female Rabbits

PubMed Central

Rodríguez-Castelán, Julia; Martínez-Gómez, Margarita; Castelán, Francisco; Cuevas, Estela

2015-01-01

Thyroidectomy induces pancreatic edema and immune cells infiltration similarly to that observed in pancreatitis. In spite of the controverted effects of hypothyroidism on serum glucose and insulin concentrations, the number and proliferation of Langerhans islet cells as well as the presence of extracellular matrix are affected depending on the islet size. In this study, we evaluated the effect of methimazole-induced hypothyroidism on the vascularization and immune cells infiltration into islets. A general observation of pancreas was also done. Twelve Chinchilla-breed female adult rabbits were divided into control (n = 6) and hypothyroid groups (n = 6, methimazole, 0.02% in drinking water for 30 days). After the treatment, rabbits were sacrificed and their pancreas was excised, histologically processed, and stained with Periodic Acid-Schiff (PAS) or Masson's Trichrome techniques. Islets were arbitrarily classified into large, medium, and small ones. The external and internal portions of each islet were also identified. Student-t-test and Mann-Whitney-U test or two-way ANOVAs were used to compare variables between groups. In comparison with control rabbits, hypothyroidism induced a strong infiltration of immune cells and a major presence of collagen and proteoglycans in the interlobular septa. Large islets showed a high vascularization and immune cells infiltration. The present results show that hypothyroidism induces pancreatitis and insulitis. PMID:26175757

Variance of molecular datings, evolution of rodents and the phylogenetic affinities between Ctenodactylidae and Hystricognathi.

PubMed Central

Huchon, D; Catzeflis, F M; Douzery, E J

2000-01-01

The von Willebrand factor (vWF) gene has been used to understand the origin and timing of Rodentia evolution in the context of placental phylogeny vWF exon 28 sequences of 15 rodent families and eight non-rodent eutherian clades are analysed with two different molecular dating methods (uniform clock on a linearized tree; quartet dating). Three main conclusions are drawn from the study of this nuclear exon. First, Ctenodactylidae (gundis) and Hystricognathi (e.g. porcupines, guinea-pigs, chinchillas) robustly cluster together in a newly recognized clade, named 'Ctenohystrica'. The Sciurognathi monophyly is subsequently rejected. Pedetidae (springhares) is an independent and early diverging rodent lineage, suggesting a convergent evolution of the multiserial enamel of rodent incisors. Second, molecular date estimates are here more influenced by accuracy and choice of the palaeontological temporal references used to calibrate the molecular clock than by either characters analysed (nucleotides versus amino acids) or species sampling. The caviomorph radiation at 31 million years (Myr) and the pig porpoise split at 63 Myr appear to be reciprocally compatible dates. Third, during the radiation of Rodentia, at least three lineages (Gliridae, Sciuroidea and Ctenohystrica) emerged close to the Cretaceous-Tertiary boundary, and their common ancestor separated from other placental orders in the Late Cretaceous. PMID:10722222

Hypothyroidism Affects Vascularization and Promotes Immune Cells Infiltration into Pancreatic Islets of Female Rabbits.

PubMed

Rodríguez-Castelán, Julia; Martínez-Gómez, Margarita; Castelán, Francisco; Cuevas, Estela

2015-01-01

Thyroidectomy induces pancreatic edema and immune cells infiltration similarly to that observed in pancreatitis. In spite of the controverted effects of hypothyroidism on serum glucose and insulin concentrations, the number and proliferation of Langerhans islet cells as well as the presence of extracellular matrix are affected depending on the islet size. In this study, we evaluated the effect of methimazole-induced hypothyroidism on the vascularization and immune cells infiltration into islets. A general observation of pancreas was also done. Twelve Chinchilla-breed female adult rabbits were divided into control (n = 6) and hypothyroid groups (n = 6, methimazole, 0.02% in drinking water for 30 days). After the treatment, rabbits were sacrificed and their pancreas was excised, histologically processed, and stained with Periodic Acid-Schiff (PAS) or Masson's Trichrome techniques. Islets were arbitrarily classified into large, medium, and small ones. The external and internal portions of each islet were also identified. Student-t-test and Mann-Whitney-U test or two-way ANOVAs were used to compare variables between groups. In comparison with control rabbits, hypothyroidism induced a strong infiltration of immune cells and a major presence of collagen and proteoglycans in the interlobular septa. Large islets showed a high vascularization and immune cells infiltration. The present results show that hypothyroidism induces pancreatitis and insulitis.

The hazard of exposure to impulse noise as a function of frequency, volume 1

NASA Astrophysics Data System (ADS)

Patterson, James H., Jr.; Carrier, Melvin, Jr.; Bordwell, Kevin; Gautier, Ilia M.; Hamernik, Roger P.

1991-06-01

The energy spectrum of a noise is known to be an important variable in determining the effects of a traumatic exposure. However, existing criteria for exposure to impulse noise do not consider the frequency spectrum of an impulse as a variable in the evaluation of the hazards to the auditory system. This report presents the results of a study that was designed to determine the relative potential that impulsive energy concentrated at different frequencies has in causing auditory system trauma. One hundred and eighteen (118) chinchilla, divided into 20 groups with 5 to 7 animals per group, were used in these experiments. Pre- and post-exposure hearing thresholds were measured at 10 test frequencies between 0.125 and 8 kHz on each animal using avoidance conditioning procedures. Quantitative histology (cochleograms) was used to determine the extent and pattern of the sensory cell damage. The noise exposure stimuli consisted of six different computer-generated narrow band tone bursts having center frequencies located at 0.260, 0.775, 1.350, 2.450, and 3.550 kHz. Each narrow band exposure stimulus was presented at two to four different intensities. An analysis of the audiometric and histological data allowed frequency weighing functions to be derived.

[Research of the durability of connective tissue complexes formed in the implantation area of various types of allograft during the experiment].

PubMed

Ioffe, O Iu; Shvets', I M; Stetsenko, O P; Tsiura, Iu P; Tarasiuk, T V; Lamashevs'kyĭ, V P; Makovets'kyĭ, I V; Furmanov, Iu O

2014-01-01

The aim of the study is to examine in the experiment on the animals the mechanical properties of connective tissue complexes formed in alloplasty area using the intraperitoneal on lay mesh and sublay methodologies with further comparison of them. The experiment has been conducted on 12 rabbits of Russian chinchilla breed. Animals were distributed in the following way: the first group--operated by intraperitoneal on lay mesh methodology (n = 6) through implantation of composite grid Proceed with one-side celullose coating produced by "Ethicon" company. The second group--performed modeling of preperitoneal plastic using two-component composite grid with large-pores Ultrapro produced by "Ethicon" company (n = 6). For the tensometric evaluation of the strength of implant integration into the red wall was used entire area of anterior red wall together with the implanted transplant. According to the deflection diagrams and dynamometer rates defined the maximum burden rates which is equivalent of muscular tissue budge against polymeric matrix. Statistically significant distinctions during 14 days were not detected; however strength during 30 days in the first group was 3 times higher than in the second group. We consider that the methodology of intraperitoneal on lay mesh can be considered as operation of choice of surgery treatment of the umbilical hernias.

Treatment of otitis media by transtympanic delivery of antibiotics

PubMed Central

Yang, Rong; Sabharwal, Vishakha; Okonkwo, Obiajulu S.; Shlykova, Nadya; Tong, Rong; Lin, Lily Yun; Wang, Weiping; Guo, Shutao; Rosowski, John J.; Pelton, Stephen I.; Kohane, Daniel S.

2017-01-01

Otitis media is the most common reason U.S. children receive antibiotics. The requisite 7- to 10-day course of oral antibiotics can be challenging to deliver in children, entails potential systemic toxicity, and encourages selection of antimicrobial-resistant bacteria. We developed a drug delivery system that, when applied once to the tympanic membrane through the external auditory canal, delivers an entire course of antimicrobial therapy to the middle ear. A penta-block copolymer poloxamer 407–polybutylphosphoester (P407-PBP) was designed to flow easily during application and then to form a mechanically strong hydrogel on the tympanic membrane. U.S. Food and Drug Administration–approved chemical permeation enhancers within the hydrogel assisted flux of the antibiotic ciprofloxacin across the membrane. This drug delivery system completely eradicated otitis media from nontypable Haemophilus influenzae (NTHi) in 10 of 10 chinchillas, whereas only 62.5% of animals receiving 1% ciprofloxacin alone had cleared the infection by day 7. The hydrogel system was biocompatible in the ear, and ciprofloxacin was undetectable systemically (in blood), confirming local drug delivery and activity. This fast-gelling hydrogel could improve compliance, minimize side effects, and prevent systemic distribution of antibiotics in one of the most common pediatric illnesses, possibly minimizing the development of antibiotic resistance. PMID:27629487

Digital holographic measurements of shape and 3D sound-induced displacements of Tympanic Membrane

PubMed Central

Lu, Weina; Dobrev, Ivo; Cheng, Jeffrey Tao; Furlong, Cosme; Rosowski, John J

2014-01-01

Acoustically-induced vibrations of the Tympanic Membrane (TM) play a primary role in the hearing process, in that these motions are the initial mechanical response of the ear to airborne sound. Characterization of the shape and 3D displacement patterns of the TM is a crucial step to a better understanding of the complicated mechanics of sound reception by the ear. In this paper, shape and sound-induced 3D displacements of the TM in cadaveric chinchillas are measured by a lensless Dual-Wavelength Digital Holography system (DWDHS). The DWDHS consists of Laser Delivery (LD), Optical Head (OH), and Computing Platform (CP) subsystems. Shape measurements are performed in double-exposure mode and with the use of two wavelengths of a tunable laser while nanometer-scale displacements are measured along a single sensitivity direction and with a constant wavelength. In order to extract the three principal components of displacement in full-field-of-view, and taking into consideration the anatomical dimensions of the TM, we combine principles of thin-shell theory together with both, displacement measurements along the single sensitivity vector and TM surface shape. To computationally test this approach, Finite Element Methods (FEM) are applied to the study of artificial geometries. PMID:24790255

Digital holographic measurements of shape and three-dimensional sound-induced displacements of tympanic membrane

NASA Astrophysics Data System (ADS)

Khaleghi, Morteza; Lu, Weina; Dobrev, Ivo; Cheng, Jeffrey Tao; Furlong, Cosme; Rosowski, John J.

2013-10-01

Acoustically induced vibrations of the tympanic membrane (TM) play a primary role in the hearing process, in that these motions are the initial mechanical response of the ear to airborne sound. Characterization of the shape and three-dimensional (3-D) displacement patterns of the TM is a crucial step to a better understanding of the complicated mechanics of sound reception by the ear. Sound-induced 3-D displacements of the TM are estimated from shape and one-dimensional displacements measured in cadaveric chinchillas using a lensless dual-wavelength digital holography system (DWDHS). The DWDHS consists of laser delivery, optical head, and computing platform subsystems. Shape measurements are performed in double-exposure mode with the use of two wavelengths of a tunable laser, while nanometer-scale displacements are measured along a single sensitivity direction with a constant wavelength. Taking into consideration the geometrical and dimensional constrains imposed by the anatomy of the TM, we combine principles of thin-shell theory together with displacement measurements along a single sensitivity vector and TM surface shape to extract the three principal components of displacement in the full-field-of-view. We test, validate, and identify limitations of this approach via the application of finite element method to artificial geometries.

Safe Direct Current Stimulation to Expand Capabilities of Neural Prostheses

PubMed Central

Fridman, Gene Y.; Della Santina, Charles C.

2014-01-01

While effective in treating some neurological disorders, neuroelectric prostheses are fundamentally limited because they must employ charge-balanced stimuli to avoid evolution of irreversible electrochemical reactions and their byproducts at the interface between metal electrodes and body fluids. Charge-balancing is typically achieved by using brief biphasic alternating current (AC) pulses, which typically excite nearby neural tissues but cannot efficiently inhibit them. In contrast, direct current (DC) applied via a metal electrode in contact with body fluids can excite, inhibit and modulate sensitivity of neurons; however, DC stimulation is biologically unsafe because it violates “safe charge injection” limits that have long been considered unavoidable constraints. In this report, we describe the design and fabrication of a safe DC stimulator (SDCS) that overcomes this constraint. The SCDS drives DC ionic current into target tissue via salt-bridge micropipette electrodes by switching valves in phase with AC square waves applied to metal electrodes contained within the device. This approach achieves DC ionic flow through tissue while still adhering to charge-balancing constraints at each electrode-saline interface. We show the SDCS’s ability to both inhibit and excite neural activity to achieve improved dynamic range during prosthetic stimulation of the vestibular part of the inner ear in chinchillas. PMID:23476007

Divergent Mechanisms for Passive Pneumococcal Resistance to β-Lactam Antibiotics in the Presence of Haemophilus influenzae

PubMed Central

Weimer, Kristin E.D.; Juneau, Richard A.; Murrah, Kyle A.; Pang, Bing; Armbruster, Chelsie E.; Richardson, Stephen H.

2011-01-01

Background. Otitis media, for which antibiotic treatment failure is increasingly common, is a leading pediatric public health problem. Methods. In vitro and in vivo studies using the chinchilla model of otitis media were performed using a β-lactamase-producing strain of nontypeable Haemophilus influenzae (NTHi 86-028NP) and an isogenic mutant deficient in β-lactamase production (NTHi 86-028NP bla) to define the roles of biofilm formation and β-lactamase production in antibiotic resistance. Coinfection studies were done with Streptococcus pneumoniae to determine if NTHi provides passive protection by means of β-lactamase production, biofilm formation, or both. Results. NTHi 86-028NP bla was resistant to amoxicillin killing in biofilm studies in vitro; however, it was cleared by amoxicillin treatment in vivo, whereas NTHi 86-028NP was unaffected in either system. NTHi 86-028NP protected pneumococcus in vivo in both the effusion fluid and bullar homogenate. NTHi 86-028NP bla and pneumococcus were both recovered from the surface-associated bacteria of amoxicillin-treated animals; only NTHi 86-028NP bla was recovered from effusion. Conclusions. Based on these studies, we conclude that NTHi provides passive protection for S. pneumoniae in vivo through 2 distinct mechanisms: production of β-lactamase and formation of biofilm communities. PMID:21220774

Coinfection with Haemophilus influenzae promotes pneumococcal biofilm formation during experimental otitis media and impedes the progression of pneumococcal disease

PubMed Central

Weimer, Kristin E.D.; Armbruster, Chelsie E.; Juneau, Richard A.; Hong, Wenzhou; Pang, Bing; Swords, W. Edward

2010-01-01

Background Otitis media is an extremely common pediatric infection, and is mostly caused by bacteria that are carried within the nasopharyngeal microbiota. It is clear that most otitis media cases involve simultaneous infection with multiple agents. Methods Chinchillas were infected with nontypeable Haemophilus influenzae, Streptococcus pneumoniae, or a combination of both organisms, and the course of disease was compared. In vitro experiments were also performed to address how coinfection impacts biofilm formation. Results The incidence of systemic disease was reduced in coinfected animals as compared to those infected with pneumococcus alone. Pneumococci were present within surface-attached biofilms in coinfected animals, and a greater proportion of translucent colony type was observed in the coinfected animals. As this colony type has been associated with pneumococcal biofilms, the impact of coinfection on pneumococcal biofilm formation was investigated. The results clearly show enhanced biofilm formation in vitro by pneumococci in the presence of H. influenzae. Conclusions Based on these data, we conclude that coinfection with H. influenzae facilitates pneumococcal biofilm formation and persistence on the middle-ear mucosal surface. This enhanced biofilm persistence correlates with delayed emergence of opaque colony variants within the bacterial population, and a resulting decrease in systemic infection. PMID:20715928

Divergent mechanisms for passive pneumococcal resistance to β-lactam antibiotics in the presence of Haemophilus influenzae.

PubMed

Weimer, Kristin E D; Juneau, Richard A; Murrah, Kyle A; Pang, Bing; Armbruster, Chelsie E; Richardson, Stephen H; Swords, W Edward

2011-02-15

Otitis media, for which antibiotic treatment failure is increasingly common, is a leading pediatric public health problem. In vitro and in vivo studies using the chinchilla model of otitis media were performed using a β-lactamase-producing strain of nontypeable Haemophilus influenzae (NTHi 86-028NP) and an isogenic mutant deficient in β-lactamase production (NTHi 86-028NP bla) to define the roles of biofilm formation and β-lactamase production in antibiotic resistance. Coinfection studies were done with Streptococcus pneumoniae to determine if NTHi provides passive protection by means of β-lactamase production, biofilm formation, or both. NTHi 86-028NP bla was resistant to amoxicillin killing in biofilm studies in vitro; however, it was cleared by amoxicillin treatment in vivo, whereas NTHi 86-028NP was unaffected in either system. NTHi 86-028NP protected pneumococcus in vivo in both the effusion fluid and bullar homogenate. NTHi 86-028NP bla and pneumococcus were both recovered from the surface-associated bacteria of amoxicillin-treated animals; only NTHi 86-028NP bla was recovered from effusion. Based on these studies, we conclude that NTHi provides passive protection for S. pneumoniae in vivo through 2 distinct mechanisms: production of β-lactamase and formation of biofilm communities.

Nonencapsulated Streptococcus pneumoniae causes otitis media during single-species infection and during polymicrobial infection with nontypeable Haemophilus influenzae.

PubMed

Murrah, Kyle A; Pang, Bing; Richardson, Stephen; Perez, Antonia; Reimche, Jennifer; King, Lauren; Wren, John; Swords, W Edward

2015-07-01

Streptococcus pneumoniae strains lacking capsular polysaccharide have been increasingly reported in carriage and disease contexts. Since most cases of otitis media involve more than one bacterial species, we aimed to determine the capacity of a nonencapsulated S. pneumoniae clinical isolate to induce disease in the context of a single-species infection and as a polymicrobial infection with nontypeable Haemophilus influenzae. Using the chinchilla model of otitis media, we found that nonencapsulated S. pneumoniae colonizes the nasopharynx following intranasal inoculation, but does not readily ascend into the middle ear. However, when we inoculated nonencapsulated S. pneumoniae directly into the middle ear, the bacteria persisted for two weeks post-inoculation and induced symptoms consistent with chronic otitis media. During coinfection with nontypeable H. influenzae, both species persisted for one week and induced polymicrobial otitis media. We also observed that nontypeable H. influenzae conferred passive protection from killing by amoxicillin upon S. pneumoniae from within polymicrobial biofilms in vitro. Therefore, based on these results, we conclude that nonencapsulated pneumococci are a potential causative agent of chronic/recurrent otitis media, and can also cause mutualistic infection with other opportunists, which could complicate treatment outcomes. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Residence of Streptococcus pneumoniae and Moraxella catarrhalis within polymicrobial biofilm promotes antibiotic resistance and bacterial persistence in vivo

PubMed Central

Perez, Antonia C.; Pang, Bing; King, Lauren B.; Tan, Li; Murrah, Kyle A.; Reimche, Jennifer L.; Wren, John T.; Richardson, Stephen H.; Ghandi, Uma; Swords, W. Edward

2014-01-01

Otitis media is an extremely common pediatric ailment caused by opportunists that reside within the nasopharynx. Inflammation within the upper airway can promote ascension of these opportunists into the middle ear chamber. Otitis media can be chronic/recurrent in nature, and a wealth of data indicates that in these cases the bacteria persist within biofilms. Epidemiological data demonstrates most cases of otitis media are polymicrobial, which may have significant impact on antibiotic resistance. In this study, we used in vitro biofilm assays and rodent infection models to examine the impact of polymicrobial infection with Moraxella catarrhalis and Streptococcus pneumoniae (pneumococcus) on biofilm resistance to antibiotic treatment and persistence in vivo. Consistent with prior work, M. catarrhalis conferred beta-lactamase dependent passive protection from beta-lactam killing to pneumococci within polymicrobial biofilms. Moreover, pneumococci increased resistance of M. catarrhalis to macrolide killing in polymicrobial biofilms. However, pneumococci increased colonization in vivo by M. catarrhalis in a quorum signal-dependent manner. We also found that co-infection with M. catarrhalis affects middle ear ascension of pneumococci in both mice and chinchillas. Therefore, we conclude that residence of M. catarrhalis and pneumococci within the same biofilm community significantly impacts resistance to antibiotic treatment and bacterial persistence in vivo. PMID:24391058

Ocular damage effects from 1338-nm pulsed laser radiation in a rabbit eye model

PubMed Central

Jiao, Luguang; Wang, Jiarui; Jing, Xiaomin; Chen, Hongxia; Yang, Zaifu

2017-01-01

The ocular damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, no retinal damage thresholds are determined in a wide interval between 0.65 ms and 80 ms, and a definite relationship between corneal damage threshold and spot size cannot be drawn from existing data points. In this paper, the in-vivo corneal damage thresholds (ED50s) were determined in New Zealand white rabbits for a single 5 ms pulse at the wavelength of 1338 nm for spot sizes from 0.28 mm to 3.55 mm. Meanwhile, the retinal damage threshold for this laser was determined in chinchilla grey rabbits under the condition that the beam was collimated, and the incident corneal spot diameter was 5.0 mm. The corneal ED50s given in terms of the corneal radiant exposure for spot diameters of 0.28, 0.94, 1.91, and 3.55 mm were 70.3, 35.6, 29.6 and 30.3 J/cm2, respectively. The retinal ED50 given in terms of total intraocular energy (TIE) was 0.904 J. The most sensitive ocular tissue to this laser changed from the cornea to retina with the increase of spot size. PMID:28663903

Basilar-membrane interference patterns from multiple internal reflection of cochlear traveling waves.

PubMed

Shera, Christopher A; Cooper, Nigel P

2013-04-01

At low stimulus levels, basilar-membrane (BM) mechanical transfer functions in sensitive cochleae manifest a quasiperiodic rippling pattern in both amplitude and phase. Analysis of the responses of active cochlear models suggests that the rippling is a mechanical interference pattern created by multiple internal reflection within the cochlea. In models, the interference arises when reverse-traveling waves responsible for stimulus-frequency otoacoustic emissions (SFOAEs) reflect off the stapes on their way to the ear canal, launching a secondary forward-traveling wave that combines with the primary wave produced by the stimulus. Frequency-dependent phase differences between the two waves then create the rippling pattern measurable on the BM. Measurements of BM ripples and SFOAEs in individual chinchilla ears demonstrate that the ripples are strongly correlated with the acoustic interference pattern measured in ear-canal pressure, consistent with a common origin involving the generation of SFOAEs. In BM responses to clicks, the ripples appear as temporal fine structure in the response envelope (multiple lobes, waxing and waning). Analysis of the ripple spacing and response phase gradients provides a test for the role of fast- and slow-wave modes of reverse energy propagation within the cochlea. The data indicate that SFOAE delays are consistent with reverse slow-wave propagation but much too long to be explained by fast waves.

Behavior of poly(glycerol sebacate) plugs in chronic tympanic membrane perforations.

PubMed

Sundback, C A; McFadden, J; Hart, A; Kulig, K M; Wieland, A M; Pereira, M J N; Pomerantseva, I; Hartnick, C J; Masiakos, P T

2012-10-01

The tympanic membrane (TM), separating the external and middle ear, consists of fibrous connective tissue sandwiched between epithelial layers. To treat chronic ear infections, tympanostomy drainage tubes are placed in surgically created holes in TMs which can become chronic perforations upon extrusion. Perforations are repaired using a variety of techniques, but are limited by morbidity, unsatisfactory closure rates, or minimal regeneration of the connective tissue. A more effective, minimally-invasive therapy is necessary to enhance the perforation closure rate. Current research utilizing decellularized or alignate materials moderately enhance closure but the native TM architecture is not restored. Poly(glycerol sebacate) (PGS) is a biocompatible elastomer which supports cell migration and enzymatically degrades in contact with vascularized tissue. PGS spool-shaped plugs were manufactured using a novel process. Using minimally invasive procedures, these elastomeric plugs were inserted into chronic chinchilla TM perforations. As previously reported, effective perforation closure occurred as both flange surfaces were covered by confluent cell layers; >90% of perforations were closed at 6-week postimplantation. This unique in vivo environment has little vascularized tissue. Consequently, PGS degradation was minimal over 16-week implantation, hindering regeneration of the TM fibrous connective tissue. PGS degradation must be enhanced to promote complete TM regeneration. Copyright © 2012 Wiley Periodicals, Inc.

Noise-induced hearing loss alters the temporal dynamics of auditory-nerve responses

PubMed Central

Scheidt, Ryan E.; Kale, Sushrut; Heinz, Michael G.

2010-01-01

Auditory-nerve fibers demonstrate dynamic response properties in that they adapt to rapid changes in sound level, both at the onset and offset of a sound. These dynamic response properties affect temporal coding of stimulus modulations that are perceptually relevant for many sounds such as speech and music. Temporal dynamics have been well characterized in auditory-nerve fibers from normal-hearing animals, but little is known about the effects of sensorineural hearing loss on these dynamics. This study examined the effects of noise-induced hearing loss on the temporal dynamics in auditory-nerve fiber responses from anesthetized chinchillas. Post-stimulus time histograms were computed from responses to 50-ms tones presented at characteristic frequency and 30 dB above fiber threshold. Several response metrics related to temporal dynamics were computed from post-stimulus-time histograms and were compared between normal-hearing and noise-exposed animals. Results indicate that noise-exposed auditory-nerve fibers show significantly reduced response latency, increased onset response and percent adaptation, faster adaptation after onset, and slower recovery after offset. The decrease in response latency only occurred in noise-exposed fibers with significantly reduced frequency selectivity. These changes in temporal dynamics have important implications for temporal envelope coding in hearing-impaired ears, as well as for the design of dynamic compression algorithms for hearing aids. PMID:20696230

The hazard of exposure to impulse noise as a function of frequency, volume 2

NASA Astrophysics Data System (ADS)

Patterson, James H., Jr.; Carrier, Melvin, Jr.; Bordwell, Kevin; Lomba, Ilia M.; Gautier, Roger P.

1991-06-01

The energy spectrum of a noise is known to be an important variable in determining the effects of a traumatic exposure. However, existing criteria for exposure to impulse noise do not consider the frequency spectrum of an impulse as a variable in the evaluation of the hazards to the auditory system. This report presents the results of a study that was designed to determine the relative potential that impulsive energy concentrated at different frequencies has in causing auditory systems trauma. One hundred and eighteen (118) chinchilla, divided into 20 groups with 5 to 7 animals per group, were used in these experiments. Pre- and post-exposure hearing thresholds were measured at 10 test frequencies between 0.125 and 8 kHz on each animal using avoidance conditioning procedures. Quantitative histology (cochleograms) was used to determine the extent and pattern of the sensory cell damage. The noise exposure stimuli consisted of six different computer-generated narrow band tone bursts having center frequencies located at 0.260, 0.775, 1.025, 1.350, 2.450, and 3.550 kHz. Each narrow band exposure stimulus was presented at two to four different intensities. An analysis of the audiometric and histological data allowed a frequency weighting function to be derived. The weighting function clearly demonstrates that equivalent amounts of impulsive energy concentrated at different frequencies is not equally hazardous to auditory function.

Peroxiredoxin-Glutaredoxin and Catalase Promote Resistance of Nontypeable Haemophilus influenzae 86-028NP to Oxidants and Survival within Neutrophil Extracellular Traps

PubMed Central

Juneau, Richard A.; Pang, Bing; Armbruster, Chelsie E.; Murrah, Kyle A.; Perez, Antonia C.

2014-01-01

Nontypeable Haemophilus influenzae (NTHI) is a common commensal and opportunistic pathogen of the human airways. For example, NTHI is a leading cause of otitis media and is the most common cause of airway infections associated with chronic obstructive pulmonary disease (COPD). These infections are often chronic/recurrent in nature and involve bacterial persistence within biofilm communities that are highly resistant to host clearance. Our previous work has shown that NTHI within biofilms has increased expression of factors associated with oxidative stress responses. The goal of this study was to define the roles of catalase (encoded by hktE) and a bifunctional peroxiredoxin-glutaredoxin (encoded by pdgX) in resistance of NTHI to oxidants and persistence in vivo. Isogenic NTHI strain 86-028NP mutants lacking hktE and pdgX had increased susceptibility to peroxide. Moreover, these strains had persistence defects in the chinchilla infection model for otitis media, as well as in a murine model for COPD. Additional work showed that pdgX and hktE were important determinants of NTHI survival within neutrophil extracellular traps (NETs), which we have shown to be an integral part of NTHI biofilms in vivo. Based on these data, we conclude that catalase and peroxiredoxin-glutaredoxin are determinants of bacterial persistence during chronic/recurrent NTHI infections that promote bacterial survival within NETs. PMID:25348637

Haemophilus parainfluenzae Strain ATCC 33392 Forms Biofilms In Vitro and during Experimental Otitis Media Infections

PubMed Central

Pang, Bing

2017-01-01

ABSTRACT Haemophilus parainfluenzae is a nutritionally fastidious, Gram-negative bacterium with an oropharyngeal/nasopharyngeal carriage niche that is associated with a range of opportunistic infections, including infectious endocarditis and otitis media (OM). These infections are often chronic/recurrent in nature and typically involve bacterial persistence within biofilm communities that are highly resistant to host clearance. This study addresses the primary hypothesis that H. parainfluenzae forms biofilm communities that are important determinants of persistence in vivo. The results from in vitro biofilm studies confirmed that H. parainfluenzae formed biofilm communities within which the polymeric matrix was mainly composed of extracellular DNA and proteins. Using a chinchilla OM infection model, we demonstrated that H. parainfluenzae formed surface-associated biofilm communities containing bacterial and host components that included neutrophil extracellular trap (NET) structures and that the bacteria mainly persisted in these biofilm communities. We also used this model to examine the possible interaction between H. parainfluenzae and its close relative Haemophilus influenzae, which is also commonly carried within the same host environments and can cause OM. The results showed that coinfection with H. influenzae promoted clearance of H. parainfluenzae from biofilm communities during OM infection. The underlying mechanisms for bacterial persistence and biofilm formation by H. parainfluenzae and knowledge about the survival defects of H. parainfluenzae during coinfection with H. influenzae are topics for future work. PMID:28674033

Haemophilus parainfluenzae Strain ATCC 33392 Forms Biofilms In Vitro and during Experimental Otitis Media Infections.

PubMed

Pang, Bing; Swords, W Edward

2017-09-01

Haemophilus parainfluenzae is a nutritionally fastidious, Gram-negative bacterium with an oropharyngeal/nasopharyngeal carriage niche that is associated with a range of opportunistic infections, including infectious endocarditis and otitis media (OM). These infections are often chronic/recurrent in nature and typically involve bacterial persistence within biofilm communities that are highly resistant to host clearance. This study addresses the primary hypothesis that H. parainfluenzae forms biofilm communities that are important determinants of persistence in vivo The results from in vitro biofilm studies confirmed that H. parainfluenzae formed biofilm communities within which the polymeric matrix was mainly composed of extracellular DNA and proteins. Using a chinchilla OM infection model, we demonstrated that H. parainfluenzae formed surface-associated biofilm communities containing bacterial and host components that included neutrophil extracellular trap (NET) structures and that the bacteria mainly persisted in these biofilm communities. We also used this model to examine the possible interaction between H. parainfluenzae and its close relative Haemophilus influenzae , which is also commonly carried within the same host environments and can cause OM. The results showed that coinfection with H. influenzae promoted clearance of H. parainfluenzae from biofilm communities during OM infection. The underlying mechanisms for bacterial persistence and biofilm formation by H. parainfluenzae and knowledge about the survival defects of H. parainfluenzae during coinfection with H. influenzae are topics for future work. Copyright © 2017 American Society for Microbiology.

Residence of Streptococcus pneumoniae and Moraxella catarrhalis within polymicrobial biofilm promotes antibiotic resistance and bacterial persistence in vivo.

PubMed

Perez, Antonia C; Pang, Bing; King, Lauren B; Tan, Li; Murrah, Kyle A; Reimche, Jennifer L; Wren, John T; Richardson, Stephen H; Ghandi, Uma; Swords, W Edward

2014-04-01

Otitis media (OM) is an extremely common pediatric ailment caused by opportunists that reside within the nasopharynx. Inflammation within the upper airway can promote ascension of these opportunists into the middle ear chamber. OM can be chronic/recurrent in nature, and a wealth of data indicates that in these cases, the bacteria persist within biofilms. Epidemiological data demonstrate that most cases of OM are polymicrobial, which may have significant impact on antibiotic resistance. In this study, we used in vitro biofilm assays and rodent infection models to examine the impact of polymicrobial infection with Moraxella catarrhalis and Streptococcus pneumoniae (pneumococcus) on biofilm resistance to antibiotic treatment and persistence in vivo. Consistent with prior work, M. catarrhalis conferred beta-lactamase-dependent passive protection from beta-lactam killing to pneumococci within polymicrobial biofilms. Moreover, pneumococci increased resistance of M. catarrhalis to macrolide killing in polymicrobial biofilms. However, pneumococci increased colonization in vivo by M. catarrhalis in a quorum signal-dependent manner. We also found that co-infection with M. catarrhalis affects middle ear ascension of pneumococci in both mice and chinchillas. Therefore, we conclude that residence of M. catarrhalis and pneumococci within the same biofilm community significantly impacts resistance to antibiotic treatment and bacterial persistence in vivo. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

[Perception and selectivity of sound duration in the central auditory midbrain].

PubMed

Wang, Xin; Li, An-An; Wu, Fei-Jian

2010-08-25

Sound duration plays important role in acoustic communication. Information of acoustic signal is mainly encoded in the amplitude and frequency spectrum of different durations. Duration selective neurons exist in the central auditory system including inferior colliculus (IC) of frog, bat, mouse and chinchilla, etc., and they are important in signal recognition and feature detection. Two generally accepted models, which are "coincidence detector model" and "anti-coincidence detector model", have been raised to explain the mechanism of neural selective responses to sound durations based on the study of IC neurons in bats. Although they are different in details, they both emphasize the importance of synaptic integration of excitatory and inhibitory inputs, and are able to explain the responses of most duration-selective neurons. However, both of the hypotheses need to be improved since other sound parameters, such as spectral pattern, amplitude and repetition rate, could affect the duration selectivity of the neurons. The dynamic changes of sound parameters are believed to enable the animal to effectively perform recognition of behavior related acoustic signals. Under free field sound stimulation, we analyzed the neural responses in the IC and auditory cortex of mouse and bat to sounds with different duration, frequency and amplitude, using intracellular or extracellular recording techniques. Based on our work and previous studies, this article reviews the properties of duration selectivity in central auditory system and discusses the mechanisms of duration selectivity and the effect of other sound parameters on the duration coding of auditory neurons.

Peroxiredoxin-glutaredoxin and catalase promote resistance of nontypeable Haemophilus influenzae 86-028NP to oxidants and survival within neutrophil extracellular traps.

PubMed

Juneau, Richard A; Pang, Bing; Armbruster, Chelsie E; Murrah, Kyle A; Perez, Antonia C; Swords, W Edward

2015-01-01

Nontypeable Haemophilus influenzae (NTHI) is a common commensal and opportunistic pathogen of the human airways. For example, NTHI is a leading cause of otitis media and is the most common cause of airway infections associated with chronic obstructive pulmonary disease (COPD). These infections are often chronic/recurrent in nature and involve bacterial persistence within biofilm communities that are highly resistant to host clearance. Our previous work has shown that NTHI within biofilms has increased expression of factors associated with oxidative stress responses. The goal of this study was to define the roles of catalase (encoded by hktE) and a bifunctional peroxiredoxin-glutaredoxin (encoded by pdgX) in resistance of NTHI to oxidants and persistence in vivo. Isogenic NTHI strain 86-028NP mutants lacking hktE and pdgX had increased susceptibility to peroxide. Moreover, these strains had persistence defects in the chinchilla infection model for otitis media, as well as in a murine model for COPD. Additional work showed that pdgX and hktE were important determinants of NTHI survival within neutrophil extracellular traps (NETs), which we have shown to be an integral part of NTHI biofilms in vivo. Based on these data, we conclude that catalase and peroxiredoxin-glutaredoxin are determinants of bacterial persistence during chronic/recurrent NTHI infections that promote bacterial survival within NETs. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

RbsB (NTHI_0632) mediates quorum signal uptake in nontypeable Haemophilus influenzae strain 86-028NP

PubMed Central

Armbruster, Chelsie E.; Pang, Bing; Murrah, Kyle; Juneau, Richard A.; Perez, Antonia C.; Weimer, Kristin E.D.; Swords, W. Edward

2011-01-01

Summary Nontypeable Haemophilus influenzae (NTHI) is a respiratory commensal and opportunistic pathogen, which persists within biofilms on airway mucosal surfaces. For many species, biofilm formation is impacted by quorum signaling. Our prior work shows that production of autoinducer-2 (AI-2) promotes biofilm development and persistence for NTHI 86-028NP. NTHI 86-028NP encodes an ABC transporter annotated as a ribose transport system that includes a protein (RbsB) with similarity to the Escherichia coli LsrB and Aggregatibacter actinomycetemcomitans RbsB proteins that bind AI-2. In this study, inactivation of rbsB significantly reduced uptake of AI-2 and the AI-2 precursor dihydroxypentanedione (DPD) by NTHI 86-028NP. Moreover, DPD uptake was not competitively inhibited by ribose or other pentose sugars. Transcript levels of rbsB increased in response to DPD and as bacteria approached stationary-phase growth. The NTHI 86-028NP rbsB mutant also formed biofilms with significantly reduced thickness and total biomass and reduced surface phosphorylcholine, similar to a luxS mutant. Infection studies revealed that loss of rbsB impaired bacterial persistence in the chinchilla middle-ear, similar to our previous results with luxS mutants. Based on these data, we conclude that in NTHI 86-028NP, RbsB is a LuxS/AI-2 regulated protein that is required for uptake of and response to AI-2. PMID:21923771

RbsB (NTHI_0632) mediates quorum signal uptake in nontypeable Haemophilus influenzae strain 86-028NP.

PubMed

Armbruster, Chelsie E; Pang, Bing; Murrah, Kyle; Juneau, Richard A; Perez, Antonia C; Weimer, Kristin E D; Swords, W Edward

2011-11-01

Nontypeable Haemophilus influenzae (NTHI) is a respiratory commensal and opportunistic pathogen, which persists within biofilms on airway mucosal surfaces. For many species, biofilm formation is impacted by quorum signalling. Our prior work shows that production of autoinducer-2 (AI-2) promotes biofilm development and persistence for NTHI 86-028NP. NTHI 86-028NP encodes an ABC transporter annotated as a ribose transport system that includes a protein (RbsB) with similarity to the Escherichia coli LsrB and Aggregatibacter actinomycetemcomitans RbsB proteins that bind AI-2. In this study, inactivation of rbsB significantly reduced uptake of AI-2 and the AI-2 precursor dihydroxypentanedione (DPD) by NTHI 86-028NP. Moreover, DPD uptake was not competitively inhibited by ribose or other pentose sugars. Transcript levels of rbsB increased in response to DPD and as bacteria approached stationary-phase growth. The NTHI 86-028NP rbsB mutant also formed biofilms with significantly reduced thickness and total biomass and reduced surface phosphorylcholine, similar to a luxS mutant. Infection studies revealed that loss of rbsB impaired bacterial persistence in the chinchilla middle ear, similar to our previous results with luxS mutants. Based on these data, we conclude that in NTHI 86-028NP, RbsB is a LuxS/AI-2 regulated protein that is required for uptake of and response to AI-2. © 2011 Blackwell Publishing Ltd.

Marking multi-channel silicon-substrate electrode recording sites using radiofrequency lesions.

PubMed

Brozoski, Thomas J; Caspary, Donald M; Bauer, Carol A

2006-01-30

Silicon-substrate multi-channel electrodes (multiprobes) have proven useful in a variety of electrophysiological tasks. When using multiprobes it is often useful to identify the site of each channel, e.g., when recording single-unit activity from a heterogeneous structure. Lesion marking of electrode sites has been used for many years. Electrolytic, or direct current (DC) lesions, have been used successfully to mark multiprobe sites in rat hippocampus [Townsend G, Peloquin P, Kloosterman F, Hetke JF, Leung LS. Recording and marking with silicon multichannel electrodes. Brain Res Brain Res Protoc 2002;9:122-9]. The present method used radio-frequency (rf) lesions to distinctly mark each of the 16 recording sites of 16-channel linear array multiprobes, in chinchilla inferior colliculus. A commercial radio-frequency lesioner was used as the current source, in conjunction with custom connectors adapted to the multiprobe configuration. In vitro bench testing was used to establish current-voltage-time parameters, as well as to check multiprobe integrity and radio-frequency performance. In in vivo application, visualization of individual-channel multiprobe recording sites was clear in 21 out of 33 sets of collicular serial-sections (i.e., probe tracks) obtained from acute experimental subjects, i.e., maximum post-lesion survival time of 2h. Advantages of the rf method include well-documented methods of in vitro calibration as well as low impact on probe integrity. The rf method of marking individual-channel sites should be useful in a variety of applications.

Efferent-Mediated Responses in Vestibular Nerve Afferents of the Alert Macaque

PubMed Central

Sadeghi, Soroush G.; Goldberg, Jay M.; Minor, Lloyd B.; Cullen, Kathleen E.

2009-01-01

The peripheral vestibular organs have long been known to receive a bilateral efferent innervation from the brain stem. However, the functional role of the efferent vestibular system has remained elusive. In this study, we investigated efferent-mediated responses in vestibular afferents of alert behaving primates (macaque monkey). We found that efferent-mediated rotational responses could be obtained from vestibular nerve fibers innervating the semicircular canals after conventional afferent responses were nulled by placing the corresponding canal plane orthogonal to the plane of motion. Responses were type III, i.e., excitatory for rotational velocity trapezoids (peak velocity, 320°/s) in both directions of rotation, consistent with those previously reported in the decerebrate chinchilla. Responses consisted of both fast and slow components and were larger in irregular (∼10 spikes/s) than in regular afferents (∼2 spikes/s). Following unilateral labyrinthectomy (UL) on the side opposite the recording site, similar responses were obtained. To confirm the vestibular source of the efferent-mediated responses, the ipsilateral horizontal and posterior canals were plugged following the UL. Responses to high-velocity rotations were drastically reduced when the superior canal (SC), the only intact canal, was in its null position, compared with when the SC was pitched 50° upward from the null position. Our findings show that vestibular afferents in alert primates show efferent-mediated responses that are related to the discharge regularity of the afferent, are of vestibular origin, and can be the result of both afferent excitation and inhibition. PMID:19091917

Efferent-mediated responses in vestibular nerve afferents of the alert macaque.

PubMed

Sadeghi, Soroush G; Goldberg, Jay M; Minor, Lloyd B; Cullen, Kathleen E

2009-02-01

The peripheral vestibular organs have long been known to receive a bilateral efferent innervation from the brain stem. However, the functional role of the efferent vestibular system has remained elusive. In this study, we investigated efferent-mediated responses in vestibular afferents of alert behaving primates (macaque monkey). We found that efferent-mediated rotational responses could be obtained from vestibular nerve fibers innervating the semicircular canals after conventional afferent responses were nulled by placing the corresponding canal plane orthogonal to the plane of motion. Responses were type III, i.e., excitatory for rotational velocity trapezoids (peak velocity, 320 degrees/s) in both directions of rotation, consistent with those previously reported in the decerebrate chinchilla. Responses consisted of both fast and slow components and were larger in irregular (approximately 10 spikes/s) than in regular afferents (approximately 2 spikes/s). Following unilateral labyrinthectomy (UL) on the side opposite the recording site, similar responses were obtained. To confirm the vestibular source of the efferent-mediated responses, the ipsilateral horizontal and posterior canals were plugged following the UL. Responses to high-velocity rotations were drastically reduced when the superior canal (SC), the only intact canal, was in its null position, compared with when the SC was pitched 50 degrees upward from the null position. Our findings show that vestibular afferents in alert primates show efferent-mediated responses that are related to the discharge regularity of the afferent, are of vestibular origin, and can be the result of both afferent excitation and inhibition.

Combination of photodynamic and ultrasonic therapy for treatment of infected wounds in animal model

NASA Astrophysics Data System (ADS)

Menyaev, Yulian A.; Zharov, Vladimir P.

2006-02-01

One of the important problems of modern medicine is treatment of infected wounds. There are many diversified expedients of treatment, but none of them obey the modern physician completely. The aim of this study is to develop and test a new combined method of photodynamic ultrasonic therapy (PDUST) for treatment of infected wounds with focus on experimental trials. PDUST is based on a combination of two methods: photodynamic (PD) therapy (PDT) with photosensitizer and low frequency ultrasonic (US) therapy with antibiotic as tools for treatment of wounds and effectively killing bacteria. The main parameters are: US frequency - 26.5 kHz; US tip elongation - 40+/-20 μm wavelength of light emitting diodes (LED) array - 660+/-10 nm; light intensity on biotissue surface - 1-2 mW/cm2; photosensitizer - an aluminum disulfonated phtalocyanine dissolved in a physiological solution in concentration 10 mg/l. The experiments were carried out with 70 male chinchilla rabbits divided into 7 groups, thus the dynamics of wounds healing were studied in different modes of PDUST. The PD and US methods supplement each other and in conjunction provide additive and especially synergetic effects. The experimental data demonstrated advantages of new technology in comparison with conventional methods in cases of treatment of extended suppurative inflammatory and profound wounds. The more detailed study of PDUST method's mechanism, which is based on low intensity of LED light, PD therapy and US influence is required.

A model for heliospheric flux-ropes

NASA Astrophysics Data System (ADS)

Nieves-Chinchilla, T.; Linton, M.; Vourlidas, A.; Hidalgo, M. A. U.

2017-12-01

This work is presents an analytical flux-rope model, which explores different levels of complexity starting from a circular-cylindrical geometry. The framework of this series of models was established by Nieves-Chinchilla et al. 2016 with the circular-cylindrical analytical flux rope model. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in a non-orthogonal geometry. The Maxwell equations are solved using tensor calculus consistent with the geometry chosen, invariance along the axial direction, and with the assumption of no radial current density. The model is generalized in terms of the radial and azimuthal dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for several example profiles of the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. For reconstruction of the heliospheric flux-ropes, the circular-cylindrical reconstruction technique has been adapted to the new geometry and applied to in situ ICMEs with a flux-rope entrained and tested with cases with clear in situ signatures of distortion. The model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures that should be evaluated with the ultimate goal of reconciling in-situ reconstructions with imaging 3D remote sensing CME reconstructions. Other effects such as axial curvature and/or expansion could be incorporated in the future to fully understand the magnetic structure.

Rabbit electroretinograms evoked by 632.8nm laser flash stimuli

NASA Astrophysics Data System (ADS)

Yang, Zai-Fu; Chen, Hong-Xia; Wang, Jia-Rui; Guan, Bo-Lin; Yu, Guang-Yuan; Zhang, Xiao-Na; Zhang, Wen-Yuan; Yang, Jing-Geng

2012-12-01

The flash electroretinography is a standard electrophysiological method and widely employed in basic research and ophthalmology clinics, of which the stimulus is usually white flash from dome stimulator. However, little is known about the electroretinograms (ERGs) evoked by monochromatic laser flash stimuli. The goal of this research effort is to quantify the ERGs of dark-adapted New Zealand rabbits elicited by He-Ne laser flash with wavelength 632.8 nm. The flash field was a Maxwellian viewing disc with angular subtense of 8.5°, 13.3° or 20.2°. The stimulus duration was 12 ms, 22 ms, 70 ms or 220 ms. The laser flash power incident on the cornea varied from 2.2 nW through 22 mW. Under the condition of 20 ms stimulus duration and 20.2° flash field, the ERG of New Zealand rabbit was compared with that of Chinchilla gray rabbit. Results showed that for the ERG b-wave, with the increase of laser energy, the amplitude first increased, then met a trough and finally increased again, the implicit time decreased first and then met a platform. While for the ERG a-wave, the amplitude increased and the implicit time decreased monotonically. Longer stimulus duration led to lower b-wave amplitude under equal flash power level. The flash field size showed limited effect on the ERG, especially on the low energy end. As compared with the pigmented rabbit, the albino rabbit was more sensitive and the threshold energy for b-wave excitation was about 10 times lower.

Biocompatibility of intravitreal injection of human mesenchymal stem cells in immunocompetent rabbits.

PubMed

Labrador Velandia, Sonia; Di Lauro, Salvatore; Alonso-Alonso, Maria Luz; Tabera Bartolomé, Soraya; Srivastava, Girish Kumar; Pastor, José Carlos; Fernandez-Bueno, Ivan

2018-01-01

To evaluate the feasibility, safety, and biocompatibility of intravitreal injection of human mesenchymal stem cells (MSCs) in immunocompetent pigmented rabbits. Thirty-two pigmented rabbits (24 females, 8 males; Chinchilla-New Zealand White) were divided into 8 groups of 4 animals. Commercially prepared human MSCs were injected (0.05 ml) into the post-lens vitreous of the right eyes. Groups 1 and 4 received isotonic medium (Ringer lactate-based), groups 2, 5, 7, and 8 received a low dose of 15 × 10 6 cells/ml. Groups 3 and 6 received a high dose of 30 × 10 6 cells/ml. Clinical signs were evaluated and scored before MSCs injection and weekly for 2 or 6 weeks. Animals were sacrificed at 2 or 6 weeks after injection. Eyes, liver, spleen, and gonads were assessed by histology and by fluorescent in situ hybridization to evaluate survival and extraocular migration of MSCs. There were no relevant clinical findings between control and MSC-injected rabbit eyes at any time point. There were also no relevant histological findings between control and MSC-injected rabbits related to ocular, liver, spleen, or gonad tissues modifications. MSCs survived intravitreally for at least 2 weeks after injection. Extraocular migration of MSCs was not detected. MSCs are safe and well-tolerated when administered intravitreally at a dose of 15 × 10 6 cells/ml in pigmented rabbits. These findings enable future research to explore the intravitreal use of commercially prepared allogenic human MSCs in clinical trials of retinal diseases.

Damage to cochlear efferents following AF64A intoxication.

PubMed

Smith, D W; Mount, R J

1993-07-01

Damage to cochlear efferents in chinchillas was assessed using transmission electron microscopy following unilateral treatment with the cholinotoxin ethylcholine mustard aziridinium ion (AF64A). AF64A was diluted in artificial perilymph to concentrations ranging from 0.5 to 100 microM. Survival times ranged from 1 to 12 weeks. At concentrations above 10 microM, widespread damage was noted to efferent fibers within the inner spiral bundle (ISB), tunnel spiral bundle (TSB), tunnel radial fibers (TRF) and efferent terminals at the base of OHCs. This damage included degeneration of fibers and terminals, delamination of mitochondria, vacuolization, and loss of cell membrane. However, at high concentrations, non-specific damage was also noted as thinnings or discontinuities of the membrane of OHCs and afferent fibers. At concentrations between 3 and 10 microM, selective damage was observed to efferent fibers within the ISB, TSB, TRF, and to terminals at the base of the OHCs, with all other structures appearing normal. At concentrations of 0.5 and 1 microM, damage was limited to efferent fibers within the TSB and ISB below the inner hair cells. In general, insult was greatest to middle- and basal-turn efferents, and longer survival times did not produce greater damage to, or loss of, efferents. These data suggest that at low concentrations, AF64A produces a partial yet selective degeneration of cochlear efferents within both the medial and lateral tracts, and that at the lowest concentrations used in these studies, AF64A produces a preferential insult on lateral olivocochlear efferents.

Anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits.

PubMed

Cruz, Yolanda; Hernández-Plata, Isela; Lucio, Rosa Angélica; Zempoalteca, René; Castelán, Francisco; Martínez-Gómez, Margarita

2017-09-01

To determine the anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits. Chinchilla adult anesthetized female rabbits were used. Anatomical, electrophysiological, and histological studies were performed. L7, S1, and some fibers from S2 and S3 form the lumbosacral trunk, which gives origin to the sciatic nerve and innervation to the gluteal region. From S2 to S3 originates the pudendal nerve, whose branches innervates the striated anal and urethra sphincters, as well as the bulbospongiosus, ischiocavernosus, and constrictor vulvae muscles. The sensory field of the pudendal nerve is ∼1800 mm 2 and is localized in the clitoral sheath and perineal and perigenital skin. The organization of the pudendal nerve varies between individuals, three patterns were identified, and one of them was present in 50% of the animals. From S3 emerge the pelvic nerve, which anastomoses to form a plexus localized between the vagina and the rectum. The innervation of the pelvic floor originates from S3 to S4 fibers. Most of the sacral spinal nerves of rabbit are mixed, carrying sensory, and motor information. Sacral nerves innervate the hind limbs, pelvic viscera, clitoris, perineal muscles, inguinal and anal glands and perineal, perigenital, and rump skin. The detailed description of the sacral nerves organization, topography, and axonal components further the knowledge of the innervation in pelvic and perinal structures of the female rabbit. This information will be useful in future studies about the physiology and physiopathology of urinary, fecal, reproductive, and sexual functions. © 2017 Wiley Periodicals, Inc.

HPN-07, a free radical spin trapping agent, protects against functional, cellular and electrophysiological changes in the cochlea induced by acute acoustic trauma

PubMed Central

Hu, Ning; Du, Xiaoping; Li, Wei; West, Matthew B.; Choi, Chul-Hee; Floyd, Robert; Kopke, Richard D.

2017-01-01

Oxidative stress is considered a major cause of the structural and functional changes associated with auditory pathologies induced by exposure to acute acoustic trauma AAT). In the present study, we examined the otoprotective effects of 2,4-disulfophenyl-N-tert-butylnitrone (HPN-07), a nitrone-based free radical trap, on the physiological and cellular changes in the auditory system of chinchilla following a six-hour exposure to 4 kHz octave band noise at 105 dB SPL. HPN-07 has been shown to suppress oxidative stress in biological models of a variety of disorders. Our results show that administration of HPN-07 beginning four hours after acoustic trauma accelerated and enhanced auditory/cochlear functional recovery, as measured by auditory brainstem responses (ABR), distortion product otoacoustic emissions (DPOAE), compound action potentials (CAP), and cochlear microphonics (CM). The normally tight correlation between the endocochlear potential (EP) and evoked potentials of CAP and CM were persistently disrupted after noise trauma in untreated animals but returned to homeostatic conditions in HPN-07 treated animals. Histological analyses revealed several therapeutic advantages associated with HPN-07 treatment following AAT, including reductions in inner and outer hair cell loss; reductions in AAT-induced loss of calretinin-positive afferent nerve fibers in the spiral lamina; and reductions in fibrocyte loss within the spiral ligament. These findings support the conclusion that early intervention with HPN-07 following an AAT efficiently blocks the propagative ototoxic effects of oxidative stress, thereby preserving the homeostatic and functional integrity of the cochlea. PMID:28832600

Indirect pathogenicity of Haemophilus influenzae and Moraxella catarrhalis in polymicrobial otitis media occurs via interspecies quorum signaling.

PubMed

Armbruster, Chelsie E; Hong, Wenzhou; Pang, Bing; Weimer, Kristin E D; Juneau, Richard A; Turner, James; Swords, W Edward

2010-07-06

Otitis media (OM) is among the leading diseases of childhood and is caused by opportunists that reside within the nasopharynx, such as Haemophilus influenzae and Moraxella catarrhalis. As with most airway infections, it is now clear that OM infections involve multiple organisms. This study addresses the hypothesis that polymicrobial infection alters the course, severity, and/or treatability of OM disease. The results clearly show that coinfection with H. influenzae and M. catarrhalis promotes the increased resistance of biofilms to antibiotics and host clearance. Using H. influenzae mutants with known biofilm defects, these phenotypes were shown to relate to biofilm maturation and autoinducer-2 (AI-2) quorum signaling. In support of the latter mechanism, chemically synthesized AI-2 (dihydroxypentanedione [DPD]) promoted increased M. catarrhalis biofilm formation and resistance to antibiotics. In the chinchilla infection model of OM, polymicrobial infection promoted M. catarrhalis persistence beyond the levels seen in animals infected with M. catarrhalis alone. Notably, no such enhancement of M. catarrhalis persistence was observed in animals infected with M. catarrhalis and a quorum signaling-deficient H. influenzae luxS mutant strain. We thus conclude that H. influenzae promotes M. catarrhalis persistence within polymicrobial biofilms via interspecies quorum signaling. AI-2 may therefore represent an ideal target for disruption of chronic polymicrobial infections. Moreover, these results strongly imply that successful vaccination against the unencapsulated H. influenzae strains that cause airway infections may also significantly impact chronic M. catarrhalis disease by removing a reservoir of the AI-2 signal that promotes M. catarrhalis persistence within biofilm.

Heat pulse excitability of vestibular hair cells and afferent neurons

PubMed Central

Brichta, Alan M.; Tabatabaee, Hessam; Boutros, Peter J.; Ahn, JoongHo; Della Santina, Charles C.; Poppi, Lauren A.; Lim, Rebecca

2016-01-01

In the present study we combined electrophysiology with optical heat pulse stimuli to examine thermodynamics of membrane electrical excitability in mammalian vestibular hair cells and afferent neurons. We recorded whole cell currents in mammalian type II vestibular hair cells using an excised preparation (mouse) and action potentials (APs) in afferent neurons in vivo (chinchilla) in response to optical heat pulses applied to the crista (ΔT ≈ 0.25°C per pulse). Afferent spike trains evoked by heat pulse stimuli were diverse and included asynchronous inhibition, asynchronous excitation, and/or phase-locked APs synchronized to each infrared heat pulse. Thermal responses of membrane currents responsible for APs in ganglion neurons were strictly excitatory, with Q10 ≈ 2. In contrast, hair cells responded with a mix of excitatory and inhibitory currents. Excitatory hair cell membrane currents included a thermoelectric capacitive current proportional to the rate of temperature rise (dT/dt) and an inward conduction current driven by ΔT. An iberiotoxin-sensitive inhibitory conduction current was also evoked by ΔT, rising in <3 ms and decaying with a time constant of ∼24 ms. The inhibitory component dominated whole cell currents in 50% of hair cells at −68 mV and in 67% of hair cells at −60 mV. Responses were quantified and described on the basis of first principles of thermodynamics. Results identify key molecular targets underlying heat pulse excitability in vestibular sensory organs and provide quantitative methods for rational application of optical heat pulses to examine protein biophysics and manipulate cellular excitability. PMID:27226448

Generating new telehealth services using a whole of community approach: experience in regional Queensland.

PubMed

Smith, Anthony C; Caffery, Liam J; Saunders, Ruth; Bradford, Natalie K; Gray, Leonard C

2014-10-01

We implemented a community telehealth project in the three towns in the Darling Downs area of Queensland over a 2-year period starting in July 2012. The purpose of the project was to generate telehealth activity in hospitals, general practice and selected residential aged care facilities. Telehealth education and training was provided to clinicians in the three towns and a community awareness campaign was delivered using advertisements in newspapers, messages in social media and presentations at community events. A total of 55 stakeholders were engaged with during 61 site visits to health care facilities during the first two years of the project. During the study period, telehealth activity in Queensland increased in the hospital sector by 39% and in the non-hospital sector by 99%. In the Darling Downs region, telehealth activity in the hospital sector increased by 104%, compared to 28% in the rest of Queensland. However, in the non-hospital sector, the increase in telehealth activity in the Darling Downs region was similar to the rest of Queensland. Telehealth services established and/or facilitated by the project included specialist geriatric ward rounds in Dalby, Chinchilla and Miles for patients in the local hospitals and nursing homes; and ad-hoc teleconsultations for children and adults living in these communities, with specialists at Toowoomba and hospitals in Brisbane. An increase in telehealth implies better access to a range of clinical services, which may result in improved clinical outcomes for patients. © The Author(s) 2014 Reprints and permissions:]br]sagepub.co.uk/journalsPermissions.nav.

Ultrastructural Analysis of the Cristae Ampullares in the Squirrel Monkey (Saimiri sciureus)*

PubMed Central

Lysakowski, Anna; Goldberg, Jay M.

2008-01-01

Type I hair cells outnumber type II hair cells (HCs) in squirrel monkey (Saimiri sciureus) cristae by a nearly 3:1 ratio. Associated with this type I HC preponderance, calyx fibers make up a much larger fraction of the afferent innervation than in rodents (Fernández et al., 1995). To study how this affected synaptic architecture, we used disector methods to estimate various features associated with type I and type II HCs in central (CZ) and peripheral (PZ) zones of monkey cristae. Each type I HC makes, on average, 5–10 ribbon synapses with the inner face of a calyx ending. Inner-face synapses outnumber those on calyx outer faces by a 40:1 ratio. Expressed per afferent, there are, on average, 15 inner-face ribbon synapses, 0.38 outer-face ribbons and 2.6 efferent boutons on calyx-bearing endings. Calyceal invaginations per type I HC range from 19 in CZ to 3 in PZ. For type II HCs, there are many more ribbons and afferent boutons in PZ than in CZ, whereas efferent innervation is relatively uniform throughout the neuroepithelium. Despite outer-face ribbons being more numerous in chinchilla than in squirrel monkey, afferent discharge properties are similar (Lysakowski et al., 1995), reinforcing the importance of inner-face ribbons in synaptic transmission. Comparisons across mammalian species suggest the prevalence of type I HCs is a primate characteristic, rather than an arboreal lifestyle adaptation. Unlike cristae, type II HCs predominate in monkey maculae. Differences in hair-cell counts may reflect the stimulus magnitudes handled by semicircular canals and otolith organs. PMID:18729176

Diet, bite force and skull morphology in the generalist rodent morphotype.

PubMed

Maestri, R; Patterson, B D; Fornel, R; Monteiro, L R; de Freitas, T R O

2016-11-01

For many vertebrate species, bite force plays an important functional role. Ecological characteristics of a species' niche, such as diet, are often associated with bite force. Previous evidence suggests a biomechanical trade-off between rodents specialized for gnawing, which feed mainly on seeds, and those specialized for chewing, which feed mainly on green vegetation. We tested the hypothesis that gnawers are stronger biters than chewers. We estimated bite force and measured skull and mandible shape and size in 63 genera of a major rodent radiation (the myomorph sigmodontines). Analysis of the influence of diet on bite force and morphology was made in a comparative framework. We then used phylogenetic path analysis to uncover the most probable causal relationships linking diet and bite force. Both granivores (gnawers) and herbivores (chewers) have a similar high bite force, leading us to reject the initial hypothesis. Path analysis reveals that bite force is more likely influenced by diet than the reverse causality. The absence of a trade-off between herbivores and granivores may be associated with the generalist nature of the myomorph condition seen in sigmodontine rodents. Both gnawing and chewing sigmodontines exhibit similar, intermediate phenotypes, at least compared to extreme gnawers (squirrels) and chewers (chinchillas). Only insectivorous rodents appear to be moving towards a different direction in the shape space, through some notable changes in morphology. In terms of diet, natural selection alters bite force through changes in size and shape, indicating that organisms adjust their bite force in tandem with changes in food items. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Masking of sounds by a background noise--cochlear mechanical correlates.

PubMed

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-05-15

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the 'suppressing' stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations.

Masking of sounds by a background noise – cochlear mechanical correlates

PubMed Central

Recio-Spinoso, Alberto; Cooper, Nigel P

2013-01-01

In the search for cochlear correlates of auditory masking by noise stimuli, we recorded basilar membrane (BM) vibrations evoked by either tone or click signals in the presence of varying levels of background noise. The BM vibrations were recorded from basal regions in healthy cochleae of anaesthetized chinchilla and gerbil. Non-linear interactions that could underpin various aspects of psychophysical masking data, including both compression and suppression at the BM level, were observed. The suppression effects, whereby the amplitude of the responses to each stimulus component could be reduced, depended on the relative intensities of the noise and the tones or clicks. Only stimulus components whose frequencies fell inside the non-linear region of the recording site, i.e. around its characteristic frequency (CF), were affected by presentation of the ‘suppressing’ stimulus (which could be either the tone or the noise). Mutual suppression, the simultaneous reduction of the responses to both tones and noise components, was observed under some conditions, but overall reductions of BM vibration were rarely observed. Moderate- to high-intensity tones suppressed BM responses to low-intensity Gaussian stimuli, including both broadband and narrowband noise. Suppression effects were larger for spectral components of the noise response that were closer to the CF. In this regime, the tone and noise stimuli became the suppressor and probe signals, respectively. This study provides the first detailed observations of cochlear mechanical correlates of the masking effects of noise. Mechanical detection thresholds for tone signals, which were arbitrarily defined using three criteria, are shown to increase in almost direct proportion to the noise level for low and moderately high noise levels, in a manner that resembles the findings of numerous psychophysical observations. PMID:23478137

Biocompatibility and antifibrotic effect of UV-cross-linked hyaluronate as a release-system for tranilast after trabeculectomy in a rabbit model--a pilot study.

PubMed

Spitzer, Martin S; Sat, Macarena; Schramm, Charlotte; Schnichels, Sven; Schultheiss, Maximilian; Yoeruek, Efdal; Dzhelebov, Dimitar; Szurman, Peter

2012-06-01

To analyze the release kinetics and the clinical and histological effects of UV-cross-linked hyaluronic acid as a release-system for the transforming growth factor β-2 antagonist tranilast with anti-phlogistic properties on intraocular pressure after trabeculectomy in an aggressive scarring animal model. Hyaluronate acid was UV-cross linked and loaded with tranilast. The release of tranilast into a buffered salt solution was assessed spectrophotometrically. Glaucoma filtration surgery, similar to that performed in clinical practice, was performed on chinchilla rabbits. The rabbits were divided in 3 groups. (Group A: trabeculectomy alone, group B: trabeculectomy with a cross-linked hyaluronic acid gel preparation and group C: trabeculectomy with cross-linked hyaluronic gel preparation mixed with tranilast). Antifibrotic efficacy was established by clinical response and histologic examination. The cross-linked gels released tranilast for up to 26 h. The release plotted as a function of the square root of time was consistent with a largely diffusion-controlled release system. Both the gel preparation alone and the gel preparation mixed with tranilast were well tolerated in vivo. No adverse effects such as inflammation, corneal toxicity or blurring of the optical media were observed. The intraocular pressure reached preoperative levels within 9 days after surgery in control animals and group B, but remained significantly reduced (p = 0.00016) in the group with tranilast until day 22. The data of this pilot study suggest that the intraoperative application of UV-crossed linked hyaluronic acid used as a slow release system for tranilast may improve the surgical outcome of glaucoma filtration surgery.

Noise-induced hearing loss increases the temporal precision of complex envelope coding by auditory-nerve fibers

PubMed Central

Henry, Kenneth S.; Kale, Sushrut; Heinz, Michael G.

2014-01-01

While changes in cochlear frequency tuning are thought to play an important role in the perceptual difficulties of people with sensorineural hearing loss (SNHL), the possible role of temporal processing deficits remains less clear. Our knowledge of temporal envelope coding in the impaired cochlea is limited to two studies that examined auditory-nerve fiber responses to narrowband amplitude modulated stimuli. In the present study, we used Wiener-kernel analyses of auditory-nerve fiber responses to broadband Gaussian noise in anesthetized chinchillas to quantify changes in temporal envelope coding with noise-induced SNHL. Temporal modulation transfer functions (TMTFs) and temporal windows of sensitivity to acoustic stimulation were computed from 2nd-order Wiener kernels and analyzed to estimate the temporal precision, amplitude, and latency of envelope coding. Noise overexposure was associated with slower (less negative) TMTF roll-off with increasing modulation frequency and reduced temporal window duration. The results show that at equal stimulus sensation level, SNHL increases the temporal precision of envelope coding by 20–30%. Furthermore, SNHL increased the amplitude of envelope coding by 50% in fibers with CFs from 1–2 kHz and decreased mean response latency by 0.4 ms. While a previous study of envelope coding demonstrated a similar increase in response amplitude, the present study is the first to show enhanced temporal precision. This new finding may relate to the use of a more complex stimulus with broad frequency bandwidth and a dynamic temporal envelope. Exaggerated neural coding of fast envelope modulations may contribute to perceptual difficulties in people with SNHL by acting as a distraction from more relevant acoustic cues, especially in fluctuating background noise. Finally, the results underscore the value of studying sensory systems with more natural, real-world stimuli. PMID:24596545

Effect of platelet activating factor with and without receptor antagonist (WEB2170) on morphology of isolated cochlear outer hair cells.

PubMed

Jung, Timothy T K; John, Earnest O; Park, Seong Kook; Park, Yong Soo; Rhee, Chong-Ku

2004-02-01

Platelet activating factor (PAF), generated from biologically active phospholipids, has been implicated as a potent inflammatory mediator and has been shown to be involved in many pathological processes, especially in inflammation and allergy. It has been suspected that PAF may be one of the inflammatory mediators in middle ear effusion that can induce sensorineural hearing loss, as observed in chronic otitis media. The PAF receptor antagonist WEB2170 has been studied extensively, and its inhibitory effects against various PAF actions are well proven in otologic systems. The purpose of our study was to determine the effect of superfusion of PAF and WEB2170 on morphological changes in isolated cochlear outer hair cells (OHCs). Isolated OHCs from adult chinchilla cochleas were exposed to albumin-phosphate-buffered saline solution (1 mg/mL), WEB2170 (5 mg/30 mL), PAF (1 micromol/L), or both PAF (I micromol/L) and WEB2170 (5 mg/30 mL). All experiments were performed at an osmolality of 305 +/- 5 mOsm at room temperature for 30 minutes. The cells were observed with an inverted microscope; the images were stored and analyzed on the Image Pro-Plus program. The OHCs exposed to control albumin-phosphate-buffered saline solution or to WEB2170 did not show any significant change in cell shape or length. The cells exposed to 1 micromol/L of PAF showed ballooning and significant shortening of the mean cell length in 15 to 20 minutes. These morphological changes in OHCs can be prevented by pretreating OHCs with WEB2170. This study demonstrated that exposure to PAF causes morphological changes in isolated OHCs that can be prevented by the PAF receptor antagonist WEB2170.

A new nanosecond UV laser at 355 nm: early results of corneal flap cutting in a rabbit model.

PubMed

Trost, Andrea; Schrödl, Falk; Strohmaier, Clemens; Bogner, Barbara; Runge, Christian; Kaser-Eichberger, Alexandra; Krefft, Karolina; Vogel, Alfred; Linz, Norbert; Freidank, Sebastian; Hilpert, Andrea; Zimmermann, Inge; Grabner, Günther; Reitsamer, Herbert A

2013-12-03

A new 355 nm UV laser was used for corneal flap cutting in an animal model and tested for clinical and morphologic alterations. Corneal flaps were created (Chinchilla Bastards; n = 25) with an UV nanosecond laser at 355 nm (150 kHz, pulse duration 850 ps, spot-size 1 μm, spot spacing 6 × 6 μm, side cut Δz 1 μm; cutting depth 130 μm) and pulse energies of 2.2 or 2.5 μJ, respectively. Following slit-lamp examination, animals were killed at 6, 12, and 24 hours after treatment. Corneas were prepared for histology (hematoxylin and eosin [HE], TUNEL-assay) and evaluated statistically, followed by ultrastructural investigations. Laser treatment was tolerated well, flap lift was easier at 2.5 μJ compared with 2.2 μJ. Standard HE at 24 hours revealed intact epithelium in the horizontal cut, with similar increase in corneal thickness at both energies. Irrespective of energy levels, TUNEL assay revealed comparable numbers of apoptotic cells in the horizontal and vertical cut at 6, 12, and 24 hours, becoming detectable in the horizontal cut as an acellular stromal band at 24 hours. Ultrastructural analysis revealed regular morphology in the epi- and endothelium, while in the stroma, disorganized collagen lamellae were detectable representing the horizontal cut, again irrespective of energy levels applied. This new UV laser revealed no epi- nor endothelial damage at energies feasible for corneal flap cutting. Observed corneal swelling was lower compared with existing UV laser studies, albeit total energy applied here was much higher. Observed loss of stromal keratinocytes is comparable with available laser systems. Therefore, this new laser is suitable for refractive surgery, awaiting its test in a chronic environment.

Expression of Glial Cell Line-Derived Neurotrophic Factor (GDNF) and the GDNF Family Receptor Alpha Subunit 1 in the Paravaginal Ganglia of Nulliparous and Primiparous Rabbits.

PubMed

García-Villamar, Verónica; Hernández-Aragón, Laura G; Chávez-Ríos, Jesús R; Ortega, Arturo; Martínez-Gómez, Margarita; Castelán, Francisco

2018-01-01

To evaluate the expression of glial cell line-derived neurotrophic factor (GDNF) and its receptor, GDNF family receptor alpha subunit 1 (GFRα-1) in the pelvic (middle third) vagina and, particularly, in the paravaginal ganglia of nulliparous and primiparous rabbits. Chinchilla-breed female rabbits were used. Primiparas were killed on postpartum day 3 and nulliparas upon reaching a similar age. The vaginal tracts were processed for histological analyses or frozen for Western blot assays. We measured the ganglionic area, the Abercrombie-corrected number of paravaginal neurons, the cross-sectional area of the neuronal somata, and the number of satellite glial cells (SGCs) per neuron. The relative expression of both GDNF and GFRα-1 were assessed by Western blotting, and the immunostaining was semiquantitated. Unpaired two-tailed Student t -test or Wilcoxon test was used to identify statistically significant differences (P≤0.05) between the groups. Our findings demonstrated that the ganglionic area, neuronal soma size, Abercrombie-corrected number of neurons, and number of SGCs per neuron were similar in nulliparas and primiparas. The relative expression of both GDNF and GFRα-1 was similar. Immunostaining for both GDNF and GFRα-1 was observed in several vaginal layers, and no differences were detected regarding GDNF and GFRα-1 immunostaining between the 2 groups. In the paravaginal ganglia, the expression of GDNF was increased in neurons, while that of GFRα-1 was augmented in the SGCs of primiparous rabbits. The present findings suggest an ongoing regenerative process related to the recovery of neuronal soma size in the paravaginal ganglia, in which GDNF and GFRα-1 could be involved in cross-talk between neurons and SGCs.

Cross-axis adaptation improves 3D vestibulo-ocular reflex alignment during chronic stimulation via a head-mounted multichannel vestibular prosthesis

PubMed Central

Dai, Chenkai; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan; Melvin, Thuy-Anh; Cullen, Kathleen E.; Della Santina, Charles C.

2012-01-01

By sensing three-dimensional (3D) head rotation and electrically stimulating the three ampullary branches of a vestibular nerve to encode head angular velocity, a multichannel vestibular prosthesis (MVP) can restore vestibular sensation to individuals disabled by loss of vestibular hair cell function. However, current spread to afferent fibers innervating non-targeted canals and otolith endorgans can distort the vestibular nerve activation pattern, causing misalignment between the perceived and actual axis of head rotation. We hypothesized that over time, central neural mechanisms can adapt to correct this misalignment. To test this, we rendered five chinchillas vestibular-deficient via bilateral gentamicin treatment and unilaterally implanted them with a head mounted MVP. Comparison of 3D angular vestibulo-ocular reflex (aVOR) responses during 2 Hz, 50°/s peak horizontal sinusoidal head rotations in darkness on the first, third and seventh days of continual MVP use revealed that eye responses about the intended axis remained stable (at about 70% of the normal gain) while misalignment improved significantly by the end of one week of prosthetic stimulation. A comparable time course of improvement was also observed for head rotations about the other two semicircular canal axes and at every stimulus frequency examined (0.2–5 Hz). In addition, the extent of disconjugacy between the two eyes progressively improved during the same time window. These results indicate that the central nervous system rapidly adapts to multichannel prosthetic vestibular stimulation to markedly improve 3D aVOR alignment within the first week after activation. Similar adaptive improvements are likely to occur in other species, including humans. PMID:21374081

Elliptic-cylindrical analytical flux-rope model for ICMEs

NASA Astrophysics Data System (ADS)

Nieves-Chinchilla, T.; Linton, M.; Hidalgo, M. A. U.; Vourlidas, A.

2016-12-01

We present an analytical flux-rope model for realistic magnetic structures embedded in Interplanetary Coronal Mass Ejections. The framework of this model was established by Nieves-Chinchilla et al. (2016) with the circular-cylindrical analytical flux rope model and under the concept developed by Hidalgo et al. (2002). Elliptic-cylindrical geometry establishes the first-grade of complexity of a series of models. The model attempts to describe the magnetic flux rope topology with distorted cross-section as a possible consequence of the interaction with the solar wind. In this model, the flux rope is completely described in the non-euclidean geometry. The Maxwell equations are solved using tensor calculus consistently with the geometry chosen, invariance along the axial component, and with the only assumption of no radial current density. The model is generalized in terms of the radial dependence of the poloidal current density component and axial current density component. The misalignment between current density and magnetic field is studied in detail for the individual cases of different pairs of indexes for the axial and poloidal current density components. This theoretical analysis provides a map of the force distribution inside of the flux-rope. The reconstruction technique has been adapted to the model and compared with in situ ICME set of events with different in situ signatures. The successful result is limited to some cases with clear in-situ signatures of distortion. However, the model adds a piece in the puzzle of the physical-analytical representation of these magnetic structures. Other effects such as axial curvature, expansion and/or interaction could be incorporated in the future to fully understand the magnetic structure. Finally, the mathematical formulation of this model opens the door to the next model: toroidal flux rope analytical model.

Dps promotes survival of nontypeable Haemophilus influenzae in biofilm communities in vitro and resistance to clearance in vivo.

PubMed

Pang, Bing; Hong, Wenzhou; Kock, Nancy D; Swords, W Edward

2012-01-01

Nontypeable Haemophilus influenzae (NTHi) is a common airway commensal and opportunistic pathogen that persists within surface-attached biofilm communities. In this study, we tested the hypothesis that bacterial stress-responses are activated within biofilms. Transcripts for several factors associated with bacterial resistance to environmental stress were increased in biofilm cultures as compared to planktonic cultures. Among these, a homolog of the DNA-binding protein from starved cells (dps) was chosen for further study. An isogenic NTHi 86-028NP dps mutant was generated and tested for resistance to environmental stress, revealing a significant survival defects in high-iron conditions, which was mediated by oxidative stress and was restored by genetic complementation. As expected, NTHi 86-028NP dps had a general stress-response defect, exhibiting decreased resistance to many types of environmental stress. While no differences were observed in density and structure of NTHi 86-028NP and NTHi 86-028NP dps biofilms, bacterial survival was decreased in NTHi 86-028NP dps biofilms as compared to the parental strain. The role of dps persistence in vivo was tested in animal infection studies. NTHi 86-028NP dps had decreased resistance to clearance after pulmonary infection of elastase-treated mice as compared to NTHi 86-028NP, whereas minimal differences were observed in clearance from mock-treated mice. Similarly, lower numbers of NTHi 86-028NP dps were recovered from middle-ear effusions and bullar homogenates in the chinchilla model for otitis media (OM). Therefore, we conclude that Dps promotes bacterial survival within NTHi biofilm communities both in vitro and in chronic infections in vivo.

Indirect Pathogenicity of Haemophilus influenzae and Moraxella catarrhalis in Polymicrobial Otitis Media Occurs via Interspecies Quorum Signaling

PubMed Central

Armbruster, Chelsie E.; Hong, Wenzhou; Pang, Bing; Weimer, Kristin E. D.; Juneau, Richard A.; Turner, James; Swords, W. Edward

2010-01-01

Otitis media (OM) is among the leading diseases of childhood and is caused by opportunists that reside within the nasopharynx, such as Haemophilus influenzae and Moraxella catarrhalis. As with most airway infections, it is now clear that OM infections involve multiple organisms. This study addresses the hypothesis that polymicrobial infection alters the course, severity, and/or treatability of OM disease. The results clearly show that coinfection with H. influenzae and M. catarrhalis promotes the increased resistance of biofilms to antibiotics and host clearance. Using H. influenzae mutants with known biofilm defects, these phenotypes were shown to relate to biofilm maturation and autoinducer-2 (AI-2) quorum signaling. In support of the latter mechanism, chemically synthesized AI-2 (dihydroxypentanedione [DPD]) promoted increased M. catarrhalis biofilm formation and resistance to antibiotics. In the chinchilla infection model of OM, polymicrobial infection promoted M. catarrhalis persistence beyond the levels seen in animals infected with M. catarrhalis alone. Notably, no such enhancement of M. catarrhalis persistence was observed in animals infected with M. catarrhalis and a quorum signaling-deficient H. influenzae luxS mutant strain. We thus conclude that H. influenzae promotes M. catarrhalis persistence within polymicrobial biofilms via interspecies quorum signaling. AI-2 may therefore represent an ideal target for disruption of chronic polymicrobial infections. Moreover, these results strongly imply that successful vaccination against the unencapsulated H. influenzae strains that cause airway infections may also significantly impact chronic M. catarrhalis disease by removing a reservoir of the AI-2 signal that promotes M. catarrhalis persistence within biofilm. PMID:20802829

Dps promotes survival of nontypeable Haemophilus influenzae in biofilm communities in vitro and resistance to clearance in vivo

PubMed Central

Pang, Bing; Hong, Wenzhou; Kock, Nancy D.; Swords, W. Edward

2012-01-01

Nontypeable Haemophilus influenzae (NTHi) is a common airway commensal and opportunistic pathogen that persists within surface-attached biofilm communities. In this study, we tested the hypothesis that bacterial stress-responses are activated within biofilms. Transcripts for several factors associated with bacterial resistance to environmental stress were increased in biofilm cultures as compared to planktonic cultures. Among these, a homolog of the DNA-binding protein from starved cells (dps) was chosen for further study. An isogenic NTHi 86-028NP dps mutant was generated and tested for resistance to environmental stress, revealing a significant survival defects in high-iron conditions, which was mediated by oxidative stress and was restored by genetic complementation. As expected, NTHi 86-028NP dps had a general stress-response defect, exhibiting decreased resistance to many types of environmental stress. While no differences were observed in density and structure of NTHi 86-028NP and NTHi 86-028NP dps biofilms, bacterial survival was decreased in NTHi 86-028NP dps biofilms as compared to the parental strain. The role of dps persistence in vivo was tested in animal infection studies. NTHi 86-028NP dps had decreased resistance to clearance after pulmonary infection of elastase-treated mice as compared to NTHi 86-028NP, whereas minimal differences were observed in clearance from mock-treated mice. Similarly, lower numbers of NTHi 86-028NP dps were recovered from middle-ear effusions and bullar homogenates in the chinchilla model for otitis media (OM). Therefore, we conclude that Dps promotes bacterial survival within NTHi biofilm communities both in vitro and in chronic infections in vivo. PMID:22919649

[Hygienic quality of feedstuffs for small mammals sent to the consultation service].

PubMed

Wolf, P; Siesenop, U; Verspohl, J; Kamphues, J

2014-04-16

Evaluation of the hygienic status of feedstuffs for small mammals, including rabbits, guinea pigs and chinchilla, kept as pets. A total of 356 feedstuffs that had been sent to the consulting service of the institute with a usable case history between January 2000 and April 2011 were analysed by sensory testing and microbiological examination. The interpretation of the microbiological results was performed with regard to benchmarks given by the working group "feed microbiology of section VI of the VDLUFA" for hay, straw and further feedstuffs. Within the sensory evaluation, the parameters "texture" (indicating the moisture content of a feed) and "smell" (mouldy or yeasty nuances) provided the first important information on feed quality. Deviations in these parameters were observed in 29.0% and 41.2%, respectively, of the analysed roughages and in 27.4% and 15.1% of mixed feeds, respectively. In about 10% of the feeds, pests (mites, Psocoptera as an indicator of mould infestation) were diagnosed microscopically. Using the differentiation of the germs as described above, faults in the hygienic quality could be detected mainly in roughage (hay, straw) and the so-called coloured feed (mixed feed based on ingredients including oat, barley or corn) whereas they occurred rarely in commercial pelleted mixed feeds based on green meal. In cases of hygienic deficits in feedstuffs, it was often unclear whether the reduced hygienic quality resulted from the production conditions (i.e. in the factory) or by improper storage of the feedstuffs by traders or pet owners. A general recommendation should be given to the owner to check the feed using a critical sensory evaluation to avoid health disorders in pets due to higher levels of germs or poisonous plants.

The Aachen miniaturized heart-lung machine--first results in a small animal model.

PubMed

Schnoering, Heike; Arens, Jutta; Sachweh, Joerg S; Veerman, Melanie; Tolba, Rene; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Vazquez-Jimenez, Jaime F

2009-11-01

Congenital heart surgery most often incorporates extracorporeal circulation. Due to foreign surface contact and the administration of foreign blood in many children, inflammatory response and hemolysis are important matters of debate. This is particularly an issue in premature and low birth-weight newborns. Taking these considerations into account, the Aachen miniaturized heart-lung machine (MiniHLM) with a total static priming volume of 102 mL (including tubing) was developed and tested in a small animal model. Fourteen female Chinchilla Bastard rabbits were operated on using two different kinds of circuits. In eight animals, a conventional HLM with Dideco Kids oxygenator and Stöckert roller pump (Sorin group, Milan, Italy) was used, and the Aachen MiniHLM was employed in six animals. Outcome parameters were hemolysis and blood gas analysis including lactate. The rabbits were anesthetized, and a standard median sternotomy was performed. The ascending aorta and the right atrium were cannulated. After initiating cardiopulmonary bypass, the aorta was cross-clamped, and cardiac arrest was induced by blood cardioplegia. Blood samples for hemolysis and blood gas analysis were drawn before, during, and after cardiopulmonary bypass. After 1 h aortic clamp time, all animals were weaned from cardiopulmonary bypass. Blood gas analysis revealed adequate oxygenation and perfusion during cardiopulmonary bypass, irrespective of the employed perfusion system. The use of the Aachen MiniHLM resulted in a statistically significant reduced decrease in fibrinogen during cardiopulmonary bypass. A trend revealing a reduced increase in free hemoglobin during bypass in the MiniHLM group could also be observed. This newly developed Aachen MiniHLM with low priming volume, reduced hemolysis, and excellent gas transfer (O(2) and CO(2)) may reduce circuit-induced complications during heart surgery in neonates.

How are Inner Hair Cells Stimulated? Evidence for multiple mechanical drives

PubMed Central

Guinan, John J.

2013-01-01

Recent studies indicate that the gap over outer hair cells (OHCs) between the reticular lamina (RL) and the tectorial membrane (TM) varies cyclically during low-frequency sounds. Variation in the RL-TM gap produces radial fluid flow in the gap that can drive inner hair cell (IHC) stereocilia. Analysis of RL-TM gap changes reveals three IHC drives in addition to classic SHEAR. For upward basilar-membrane (BM) motion, IHC stereocilia are deflected in the excitatory direction by SHEAR and OHC-MOTILITY, but in the inhibitory direction by TM-PUSH and CILIA-SLANT. Upward BM motion causes OHC somatic contraction which tilts the RL, compresses the RL-TM gap over IHCs and expands the RL-TM gap over OHCs, thereby producing an outward (away from the IHCs) radial fluid flow which is the OHC-MOTILITY drive. For upward BM motion, the force that moves the TM upward also compresses the RL-TM gap over OHCs causing inward radial flow past IHCs which is the TM-PUSH drive. Motions that produce large tilting of OHC stereocilia squeeze the supra-OHC RL-TM gap and caused inward radial flow past IHCs which is the CILIA-SLANT drive. Combinations of these drives explain: (1) the reversal at high sound levels of auditory nerve (AN) initial peak (ANIP) responses to clicks, and medial olivocochlear (MOC) inhibition of ANIP responses below, but not above, the ANIP reversal, (2) dips and phase reversals in AN responses to tones in cats and chinchillas, (3) hypersensitivity and phase reversals in tuning-curve tails after OHC ablation, and (4) MOC inhibition of tail-frequency AN responses. The OHC-MOTILITY drive provides another mechanism, in addition to BM motion amplification, that uses active processes to enhance the output of the cochlea. The ability of these IHC drives to explain previously anomalous data provides strong, although indirect, evidence that these drives are significant and presents a new view of how the cochlea works at frequencies below 3 kHz. PMID:22959529

On The Constitutive Properties Of Strongly Magnetized Matter Observed In A Class Of Solar Ejecta

NASA Astrophysics Data System (ADS)

Berdichevsky, D. B.

2013-12-01

Several studies of the transient events known as magnetic clouds at 1 AU suggest that they possess the ';1/2' anomalous value for its adiabatic, polytropic index, i.e., γ= 1/2, which implies that the temperature of the plasma decreases with increased density[1-3]. Coronal mass ejections commonly observed by missions like The Solar Terrestrial Relations Observatory (STEREO) have been successfully modeled previously by Berdichevsky Stenborg and Vourlidas[4] as magnetic flux-ropes which propagate from the Sun with uniform velocity. Building on this existing analytical three-dimensional magnetohydrodynamic (MHD) model of a magnetic flux-rope, we present an interpretation of the anomalous and somewhat counterintuitive dynamic property mentioned above. Using plasma and magnetic field observations by the Wind spacecraft for the magnetic cloud of June 2, 1998, we argue that this anomalous polytropic index is indeed a consequence of thermodynamic processes in this strongly magnetized matter. We show that the derived models of Berdichevsky et al.[5, 6] easily accommodate a familiar thermodynamic explanation of this property. Such an explanation may shed light also on the evolution of other astrophysical observations such as remnants in nebulae of past super-novae, as well other transient interstellar events. This MHD solution may be a good way to go beyond gas-dynamics in the development of a coherent picture of shock and its driver, as they are becoming a current interpretation. 1Osherovich, V.A., 1997, Proc. 31st, ESLAB Symp. Correlated Phenomena at the Sun, in the Heliosphere and in Geospace. 2Sittler, E.C., and L.F., Burlaga, 1998, J. Geophys. Res., 103, 17447. 3Nieves-Chinchilla T., and A., Figueroa-Viñas, 2008, J. Geophys. Res., 113, DOI: 10.1029/2007JA012703 4Berdichevsky, Stenborg, and Vourlidas, 2011, ApJ, 741, 47. 5Berdichevsky, D.B., R.L., Lepping, C.J., Farrugia, 2003, Phys.Rev. E, 67, DOI: 10.1103/PhysRevE036405. 6Berdichevsky, D.B. , 2012, Sol. Phys., 284, 245.

Separating the contributions of olivocochlear and middle ear muscle reflexes in modulation of distortion product otoacoustic emission levels.

PubMed

Wolter, Nikolaus E; Harrison, Robert V; James, Adrian L

2014-01-01

Mediated by the medial olivocochlear system (MOCS), distortion product otoacoustic emission (DPOAE) levels are reduced by presentation of contralateral acoustic stimuli. Such acoustic signals can also evoke a middle ear muscle reflex (MEMR) that also attenuates recorded DPOAE levels. Our aim is to clearly differentiate these two inhibitory mechanisms and to analyze each separately, perhaps allowing the development of novel tests of hearing function. DPOAE were recorded in real time from chinchillas with normal auditory brainstem response thresholds and middle ear function. Amplitude reduction and its onset latency caused by contralateral presentation of intermittent narrow-band noise (NBN) were measured. Stapedius and tensor tympani muscle tendons were divided without disturbing the ossicular chain, and DPOAE testing was repeated. Peak reduction of (2f1 - f2) DPOAE levels occurred when the center frequency of contralateral NBN approximated the primary tone f2, indicating an f2-frequency-specific response. For a 4.5-kHz centered NBN, DPOAE (f2 = 4.4 kHz) inhibition was 0.1 dB (p < 0.001). This response remained present after tendon division, consistent with an MOCS origin. Low-frequency NBN (center frequency: 0.5 kHz) reduced otoacoustic emission levels (0.1 dB, p < 0.001) across a wide range of DPOAE frequencies. This low-frequency response was abolished by division of the middle ear muscle tendons, clearly indicating MEMR involvement. Following middle ear muscle tendon division, DPOAE inhibition by contralateral stimuli approximating the primary tone f2 persists, whereas responses evoked by lower contralateral frequencies are abolished. This distinguishes the different roles of the MOCS (f2 frequency specific) and MEMR (low frequency only) in contralateral modulation of DPOAE. This analysis helps clarify the pathways involved in an objective test that might have clinical benefit in the testing of neonates.

Effects of sensorineural hearing loss on temporal coding of harmonic and inharmonic tone complexes in the auditory nerve

PubMed Central

Kale, Sushrut; Micheyl, Christophe; Heinz, Michael G.

2013-01-01

Listeners with sensorineural hearing loss (SNHL) often show poorer thresholds for fundamental-frequency (F0) discrimination, and poorer discrimination between harmonic and frequency-shifted (inharmonic) complex tones, than normal-hearing (NH) listeners—especially when these tones contain resolved or partially resolved components. It has been suggested that these perceptual deficits reflect reduced access to temporal-fine-structure (TFS) information, and could be due to degraded phase-locking in the auditory nerve (AN) with SNHL. In the present study, TFS and temporal-envelope (ENV) cues in single AN-fiber responses to bandpass-filtered harmonic and inharmonic complex tones were measured in chinchillas with either normal hearing or noise-induced SNHL. The stimuli were comparable to those used in recent psychophysical studies of F0 and harmonic/inharmonic discrimination. As in those studies, the rank of the center component was manipulated to produce different resolvability conditions, different phase relationships (cosine and random phase) were tested, and background noise was present. Neural TFS and ENV cues were quantified using cross-correlation coefficients computed using shuffled cross-correlograms between neural responses to REF (harmonic) and TEST (F0- or frequency-shifted) stimuli. In animals with SNHL, AN-fiber tuning curves showed elevated thresholds, broadened tuning, best-frequency shifts, and downward shifts in the dominant TFS response component; however, no significant degradation in the ability of AN fibers to encode TFS or ENV cues was found. Consistent with optimal-observer analyses, the results indicate that TFS and ENV cues depended only on the relevant frequency shift in Hz and thus were not degraded because phase-locking remained intact. These results suggest that perceptual “TFS-processing” deficits do not simply reflect degraded phase-locking at the level of the AN. To the extent that performance in F0 and harmonic/inharmonic discrimination tasks depend on TFS cues, it is likely through a more complicated (sub-optimal) decoding mechanism, which may involve “spatiotemporal” (place-time) neural representations. PMID:23716215

Clinical Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum infections in dogs.

PubMed

Dubey, J P; Chapman, Jennifer L; Rosenthal, Benjamin M; Mense, M; Schueler, Ronald L

2006-04-15

Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum are related apicomplexans that can cause systemic illness in many species of animals, including dogs. We investigated one breeder's 25 Basset Hounds for these infections. In addition, tissues from dogs and other non-canine hosts previously reported as S. canis infections were studied retrospectively. Schizonts resembling those of S. neurona, and recognized by polyclonal rabbit anti-S. neurona antibodies, were found in six of eight retrospective cases, as well as in two additional dogs (one Basset Hound, one Springer Spaniel) not previously reported. S. neurona schizonts were found in several tissues including the central nervous system, lungs, and kidneys. Fatal toxoplasmosis was diagnosed in an adult dog, and neosporosis was diagnosed in an adult and a pup related to the one diagnosed with S. neurona. No serological reactivity to S. neurona antibodies occurred when S. canis-like liver schizonts were retrospectively assayed from two dogs, a dolphin, a sea lion, a horse, a chinchilla, a black or either of two polar bears. Sequencing conserved (18S) and variable (ITS-1) portions of nuclear ribosomal DNA isolated from the schizont-laden liver of a polar bear distinguished it from all previously characterized species of Sarcocystis. We take this genetic signature as provisionally representative of S. canis, an assumption that should be tested with future sequencing of similar liver infections in other mammalian hosts. These findings further extend the uncharacteristically broad intermediate host range for S. neurona, which also causes a neurologic disease in cats, mink, raccoons, skunks, Pacific harbor seals, ponies, zebras, lynxes, and sea otters. Further work is necessary to delineate the causative agent(s) of other cases of canine sarcocystosis, and in particular to specify the attributes of S. canis, which corresponds morphologically to infections reported from wide range of terrestrial and marine mammals.

Gene Expression Differences in Infected and Noninfected Middle Ear Complementary DNA Libraries

PubMed Central

Kerschner, Joseph E.; Horsey, Edward; Ahmed, Azad; Erbe, Christy; Khampang, Pawjai; Cioffi, Joseph; Hu, Fen Ze; Post, James Christopher; Ehrlich, Garth D.

2010-01-01

Objectives To investigate genetic differences in middle ear mucosa (MEM) with nontypeable Haemophilus influenzae (NTHi) infection. Genetic upregulation and downregulation occurs in MEM during otitis media (OM) pathogenesis. A comprehensive assessment of these genetic differences using the techniques of complementary DNA (cDNA) library creation has not been performed. Design The cDNA libraries were constructed from NTHi-infected and noninfected chinchilla MEM. Random clones were picked, sequenced bidirectionally, and submitted to the National Center for Biotechnology Information (NCBI) Expressed Sequence Tags database, where they were assigned accession numbers. These numbers were used with the basic local alignment search tool (BLAST) to align clones against the nonredundant nucleotide database at NCBI. Results Analysis with the Web-based statistical program FatiGO identified several biological processes with significant differences in numbers of represented genes. Processes involved in immune, stress, and wound responses were more prevalent in the NTHi-infected library. S100 calcium-binding protein A9 (S100A9); secretory leukoprotease inhibitor (SLPI); β2-microglobulin (B2M); ferritin, heavy-chain polypeptide 1 (FTH1); and S100 calcium-binding protein A8 (S100A8) were expressed at significantly higher levels in the NTHi-infected library. Calcium-binding proteins S100A9 and S100A8 serve as markers for inflammation and have antibacterial effects. Secretory leukoprotease inhibitor is an antibacterial protein that inhibits stimuli-induced MUC1, MUC2, and MUC5AC production. Conclusions A number of genes demonstrate changes during the pathogenesis of OM, including SLPI, which has an impact on mucin gene expression; this expression is known to be an important regulator in OM. The techniques described herein provide a framework for future investigations to more thoroughly understand molecular changes in the middle ear, which will likely be important in developing new therapeutic and intervention strategies. PMID:19153305

The effects of experimentally induced conductive hearing loss on spectral and temporal aspects of sound transmission through the ear.

PubMed

Eric Lupo, J; Koka, Kanthaiah; Thornton, Jennifer L; Tollin, Daniel J

2011-02-01

Conductive hearing loss (CHL) is known to produce hearing deficits, including deficits in sound localization ability. The differences in sound intensities and timing experienced between the two tympanic membranes are important cues to sound localization (ILD and ITD, respectively). Although much is known about the effect of CHL on hearing levels, little investigation has been conducted into the actual impact of CHL on sound location cues. This study investigated effects of CHL induced by earplugs on cochlear microphonic (CM) amplitude and timing and their corresponding effect on the ILD and ITD location cues. Acoustic and CM measurements were made in 5 chinchillas before and after earplug insertion, and again after earplug removal using pure tones (500 Hz to 24 kHz). ILDs in the unoccluded condition demonstrated position and frequency dependence where peak far-lateral ILDs approached 30 dB for high frequencies. Unoccluded ear ITD cues demonstrated positional and frequency dependence with increased ITD cue for both decreasing frequency (±420 μs at 500 Hz, ±310 μs for 1-4 kHz) and increasingly lateral sound source locations. Occlusion of the ear canal with foam plugs resulted in a mild, frequency-dependent conductive hearing loss of 10-38 dB (mean 31 ± 3.9 dB) leading to a concomitant frequency dependent increase in ILDs at all source locations. The effective ITDs increased in a frequency dependent manner with ear occlusion as a direct result of the acoustic properties of the plugging material, the latter confirmed via acoustical measurements using a model ear canal with varying volumes of acoustic foam. Upon ear plugging with acoustic foam, a mild CHL is induced. Furthermore, the CHL induced by acoustic foam results in substantial changes in the magnitudes of both the ITD and ILD cues to sound location. Copyright © 2010 Elsevier B.V. All rights reserved.

The effects of experimentally induced conductive hearing loss on spectral and temporal aspects of sound transmission through the ear

PubMed Central

Lupo, J. Eric; Koka, Kanthaiah; Thornton, Jennifer L.; Tollin, Daniel J.

2010-01-01

Conductive hearing loss (CHL) is known to produce hearing deficits, including deficits in sound localization ability. The differences in sound intensities and timing experienced between the two tympanic membranes are important cues to sound localization (ILD and ITD, respectively). Although much is known about the effect of CHL on hearing levels, little investigation has been conducted into the actual impact of CHL on sound location cues. This study investigated effects of CHL induced by earplugs on cochlear microphonic (CM) amplitude and timing and their corresponding effect on the ILD and ITD location cues. Acoustic and CM measurements were made in 5 chinchillas before and after earplug insertion, and again after earplug removal using pure tones (500 Hz to 24 kHz). ILDs in the unoccluded condition demonstrated position and frequency dependence where peak far-lateral ILDs approached 30 dB for high frequencies. Unoccluded ear ITD cues demonstrated positional and frequency dependence with increased ITD cue for both decreasing frequency (± 420 µs at 500 Hz, ± 310 µs for 1–4 kHz ) and increasingly lateral sound source locations. Occlusion of the ear canal with foam plugs resulted in a mild, frequency-dependent conductive hearing loss of 10–38 dB (mean 31 ± 3.9 dB) leading to a concomitant frequency dependent increase in ILDs at all source locations. The effective ITDs increased in a frequency dependent manner with ear occlusion as a direct result of the acoustic properties of the plugging material, the latter confirmed via acoustical measurements using a model ear canal with varying volumes of acoustic foam. Upon ear plugging with acoustic foam, a mild CHL is induced. Furthermore, the CHL induced by acoustic foam results in substantial changes in the magnitudes of both the ITD and ILD cues to sound location. PMID:21073935

Photocoagulation in rabbits: optical coherence tomographic lesion classification, wound healing reaction, and retinal temperatures.

PubMed

Koinzer, Stefan; Hesse, Carola; Caliebe, Amke; Saeger, Mark; Baade, Alexander; Schlott, Kerstin; Brinkmann, Ralf; Roider, Johann

2013-09-01

The rabbit is the most common animal model to study retinal photocoagulation lesions. We present a classification of retinal lesions from rabbits, that is based on optical coherence tomographic (OCT) findings, temperature data, and OCT-follow-up data over 3 months. Four hundred eighty-six photocoagulation lesions (modified Zeiss Visulas® 532 nm CW laser, lesion diameter 133 µm, exposure duration 200  milliseconds or variable, power variable) were analyzed from six eyes of three chinchilla gray rabbits. During the irradiation of each lesion, we used an optoacoustics-based method to measure the retinal temperature profile. Two hours, 1 week, 1 month, and 3 months after the treatment, we obtained fundus color and OCT (Spectralis®) images of each lesion. We classified the lesions according to their OCT morphology and correlated the findings to ophthalmoscopic and OCT lesion diameters, and temperatures. Besides an undetectable lesion class 0, we discerned subthreshold lesions that were invisible on the fundus but detectable in OCT (classes 1 and 2), very mild lesions that were partly visible on the fundus (class 3), and 3 classes of suprathreshold lesions. OCT greatest linear diameters (GLDs) were larger than ophthalmoscopic lesion diameters, both increased for increasing classes, and GLDs decreased over 3 months within each class. Mean peak end temperatures for 200  milliseconds lesions ranged from 61°C in class 2 to 80°C in class 6. The seven step rabbit lesion classifier is distinct from a previously published human lesion classifier. Threshold lesions are generated at comparable temperatures in rabbits and humans, while more intense lesions are created at lower temperatures in rabbits. The OCT lesion classifier could replace routine histology in some studies, and the presented data may be used to estimate lesion end temperatures from OCT images. © 2013 Wiley Periodicals, Inc.

Spontaneous hair cell regeneration in the mouse utricle following gentamicin ototoxicity.

PubMed

Kawamoto, Kohei; Izumikawa, Masahiko; Beyer, Lisa A; Atkin, Graham M; Raphael, Yehoash

2009-01-01

Whereas most epithelial tissues turn-over and regenerate after a traumatic lesion, this restorative ability is diminished in the sensory epithelia of the inner ear; it is absent in the cochlea and exists only in a limited capacity in the vestibular epithelium. The extent of regeneration in vestibular hair cells has been characterized for several mammalian species including guinea pig, rat, and chinchilla, but not yet in mouse. As the fundamental model species for investigating hereditary disease, the mouse can be studied using a wide variety of genetic and molecular tools. To design a mouse model for vestibular hair cell regeneration research, an aminoglycoside-induced method of complete hair cell elimination was developed in our lab and applied to the murine utricle. Loss of utricular hair cells was observed using scanning electron microscopy, and corroborated by a loss of fluorescent signal in utricles from transgenic mice with GFP-positive hair cells. Regenerative capability was characterized at several time points up to six months following insult. Using scanning electron microscopy, we observed that as early as two weeks after insult, a few immature hair cells, demonstrating the characteristic immature morphology indicative of regeneration, could be seen in the utricle. As time progressed, larger numbers of immature hair cells could be seen along with some mature cells resembling surface morphology of type II hair cells. By six months post-lesion, numerous regenerated hair cells were present in the utricle, however, neither their number nor their appearance was normal. A BrdU assay suggested that at least some of the regeneration of mouse vestibular hair cells involved mitosis. Our results demonstrate that the vestibular sensory epithelium in mice can spontaneously regenerate, elucidate the time course of this process, and identify involvement of mitosis in some cases. These data establish a road map of the murine vestibular regenerative process, which can be used for elucidating the molecular events that govern this process.

Public health implications of changing rodent importation patterns— United States, 1999–2013

PubMed Central

Lankau, Emily W.; Sinclair, Julie R.; Schroeder, Betsy A.; Galland, G. Gale; Marano, Nina

2015-01-01

Summary The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits, and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999 –2013 by shipment volume and geographic origin, source (e.g., wild -caught versus captive-or commercially bred), intended purpose, and rodent taxonomy. Live rodent imports increased from 2,737 animals during 1999 to 173,761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild-captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs, and hamsters arriving from other countries in North America were predominant taxa underlying this trend . After 2003, African-origin imports became sporadic events under the federal permit process. These patterns suggest development of large -scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild-captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high-density rodent breeding(e.g. , lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re-evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks. PMID:26245515

Public Health Implications of Changing Rodent Importation Patterns - United States, 1999-2013.

PubMed

Lankau, E W; Sinclair, J R; Schroeder, B A; Galland, G G; Marano, N

2017-04-01

The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999-2013 by shipment volume and geographic origin, source (e.g. wild-caught versus captive- or commercially bred), intended purpose and rodent taxonomy. Live rodent imports increased from 2737 animals during 1999 to 173 761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild-captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs and hamsters arriving from other countries in North America were predominant taxa underlying this trend. After 2003, African-origin imports became sporadic events under the federal permit process. These patterns suggest development of large-scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild-captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high-density rodent breeding (e.g. lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re-evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Time course of organ of Corti degeneration after noise exposure.

PubMed

Bohne, Barbara A; Kimlinger, Melissa; Harding, Gary W

2017-02-01

From our permanent collection of plastic-embedded flat preparations of chinchilla cochleae, 22 controls and 199 ears from noise-exposed animals were used to determine when, postexposure, hair cell (HC) and supporting cell (SC) degeneration were completed. The exposed ears were divided into four groups based on exposure parameters: 0.5- or 4-kHz octave band of noise at moderate (M) or high (H) intensities. Postexposure survival ranged from <1 h to 2.5 y. Ears fixed ≤ 0-12 h postexposure were called 'acute'. For 'chronic' ears, postexposure survival was ≥7 d for groups 0.5M and 4M, ≥ 1 mo for the 4H group and ≥7 mo for the 0.5H group. The time course of inner-ear degeneration after noise exposure was determined from data in the 0.5H and 4H groups because these groups contained ears with intermediate survival times. Outer hair cells (OHCs) began dying during the exposure. OHC loss slowed down beyond 1 mo but was still present. Conversely, much inner hair cell loss was delayed until 1-3 wk postexposure. Outer pillar and inner pillar losses were present at a low level in acute ears but increased exponentially thereafter. These results are the first to demonstrate quantitatively that hair cells (HCs) and supporting cells (SCs) may continue to degenerate for months postexposure. With short postexposure survivals, the remaining SCs often had pathological changes, including: buckled pillar bodies, shifted Deiters' cell (DC) nuclei, detachment of DCs from the basilar membrane and/or splitting of the reticular lamina. These pathological changes appeared to allow endolymph and perilymph to intermix in the fluid spaces of the organ of Corti, damaging additional HCs, SCs and nerve fibers. This mechanism may account for some postexposure degeneration. In ears exposed to moderate noise, some of these SC changes appeared to be reversible. In ears exposed to high-level noise, these changes appeared to indicate impending degeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Expression of urease by Haemophilus influenzae during human respiratory tract infection and role in survival in an acid environment

PubMed Central

2011-01-01

Background Nontypeable Haemophilus influenzae is a common cause of otitis media in children and lower respiratory tract infection in adults with chronic obstructive pulmonary disease (COPD). Prior studies have shown that H. influenzae expresses abundant urease during growth in the middle ear of the chinchilla and in pooled human sputum, suggesting that expression of urease is important for colonization and infection in the hostile environments of the middle ear and in the airways in adults. Virtually nothing else is known about the urease of H. influenzae, which was characterized in the present study. Results Analysis by reverse transcriptase PCR revealed that the ure gene cluster is expressed as a single transcript. Knockout mutants of a urease structural gene (ureC) and of the entire ure operon demonstrated no detectable urease activity indicating that this operon is the only one encoding an active urease. The ure operon is present in all strains tested, including clinical isolates from otitis media and COPD. Urease activity decreased as nitrogen availability increased. To test the hypothesis that urease is expressed during human infection, purified recombinant urease C was used in ELISA with pre acquisition and post infection serum from adults with COPD who experienced infections caused by H. influenzae. A total of 28% of patients developed new antibodies following infection indicating that H. influenzae expresses urease during airway infection. Bacterial viability assays performed at varying pH indicate that urease mediates survival of H. influenzae in an acid environment. Conclusions The H. influenzae genome contains a single urease operon that mediates urease expression and that is present in all clinical isolates tested. Nitrogen availability is a determinant of urease expression. H. influenzae expresses urease during human respiratory tract infection and urease is a target of the human antibody response. Expression of urease enhances viability in an acid environment. Taken together, these observations suggest that urease is important for survival and replication of H. influenzae in the human respiratory tract. PMID:21843372

INTESTINAL LIFE CYCLE OF EIMERIA CALIGINOSA (APICOMPLEXA: EIMERIIDAE) FROM THE DUSKY RICE RAT, MELANOMYS CALIGINOSUS (RODENTIA: CRICETIDAE: SIGMODONTINAE) IN COSTA RICA.

PubMed

Chinchilla, Misael; Valerio, Idalia; Sanchez, Ronald; Duszynski, Donald

2018-05-08

The endogenous life cycle of Eimeria caliginosa was studied in experimentally-infected dusky rice rats, Melanomys caliginosus. All endogenous stages were located in the epithelial cells of villi in the small intestine. Both Giemsa-stained mucosal scrapings and histological sections were studied for the diagnosis of all the life cycle stages. Eimeria caliginosa has 3 generations of meronts (M) that differ by size, shape, and number of merozoites (m), which also differ in their size, shape, and location of their nuclei within the cytoplasm of the meronts. The 3 meront types, M1-M3, respectively, had 20-33 (m1), 5-9 (m2), and 13-16 (m3) merozoites. Macrogametocytes and microgametocytes, as well as macrogametes and microgametes, completed the sexual cycle, which conclude with the formation of unsporulated oocysts. This parasite's endogenous development produced severe intestinal lesions in the experimentally-infected dusky rice rats. In our ongoing work to understand the biodiversity present in plants and animals of our protected Reserva Biológica Alberto Manuel Brenes (ReBAMB) field station in Costa Rica, we now have discovered 3 new Eimeria species, and this is the second complete life cycle in which we document both the asexual and sexual stages The presence of Eimeria caliginosa was discovered in Costa Rica, in the dusky rice rat, Melanomys caliginosus (Tomes, 1860), captured in the protected Reserva Biológica Alberto Manuel Brenes (ReBAMB) in San Ramón, Alajuela, Costa Rica (Chinchilla et al. 2014). The original description was based on sporulated oocyst characteristics, but there was no information known about this parasite or its life history at the time of our discovery. Now, using careful experimental protocols, we are able to offer a description of the endogenous stages of the intestinal life cycle of E. caliginosa in M. caliginosus were able to determine the prepatent and patent periods, and we were able to make some observations about the intestinal pathology caused by E. caliginosa in its natural host, the dusky rice rat.

Caecal fermentation characteristics, blood composition and growth of rabbits on substitution of soya-bean meal by unconventional high-glucosinolate mustard ( Brassica juncea) meal as protein supplement.

PubMed

Tripathi, M K; Mishra, A S; Mondal, D; Misra, A K; Prasad, R; Jakhmola, R C

2008-02-01

Effect of graded levels of high-glucosinolate mustard (Brassica juncea) meal as substitute of soya-bean meal (SBM) in broiler rabbit diets was studied. Forty weaning rabbits of Soviet Chinchilla and White Giant breed were randomly allocated to one of four experimental diets containing mustard meal (MM) 0, 80, 160 and 245 g/kg. The experiment lasted for 8 weeks. MM had 54.8 mg total glucosinolates (TGLSs) per g dry matter (DM). Diets had TGLS 3.8, 8.4 and 11.98 mg/g DM in 80, 160 and 245 g MM diets, respectively. MM-incorporated diets had higher digestible and linearly (P < 0.01) higher metabolisable energy (ME) content. However, the effect on total tract apparent digestibility of DM, and crude protein was quadratic. Average daily gain (ADG) reduced (P < 0.05) linearly with increasing MM levels in diet, still 80 and 160 g MM diets had similar ADG compared to that of SBM diet. Caecum weight reduced linearly (P < 0.05) with increasing MM levels in diet. The pH of caecal content ranged between 5.85 and 6.19, total N between 1.19 and 1.48 (g per 100 g) and total volatile fatty acids between 4.7 and 5.8 mmol per 100 g, and they were not statistically different. NH3-N ranged between 31.2 and 39.0 mg per 100 ml, and reduced linearly (P < 0.05) while trichloroacetic acid-precipitable nitrogen increased linearly (P < 0.01, ranged between 114 and 247 mg per 100 ml) with increasing MM levels in diet. Blood haemoglobin, packed cell volume and lymphocytes were higher (quadratic effects, P < 0.05) on 245 MM diet, whereas white blood cell count reduced linearly (P < 0.01). Serum aspartate aminotransferase increased linearly (P < 0.01) while alanine aminotransferase and alkaline phosphatase activity, protein, erythrocytes sedimentation rate and red blood cell counts were not affected by MM. Serum Cu, Na and K content increased linearly (P < 0.05) with increasing MM levels. Liver Cu concentration showed quadratic (P < 0.05) increase. Rabbits tolerated 8.4 mg TGLS per g diet (160 g MM per kg) during active growth without any apparent effect on health and growth. It is concluded that MM can replace up to 66% SBM protein in rabbit feeding, whereas complete replacement of SBM with MM reduced feed intake and ADG by 23% and 13%, respectively. Further studies are required to confirm these inclusion levels and glucosinolate tolerance of rabbits.

[Effects of the of renal warm ischemia time on the recovery of filtration function in the experiment].

PubMed

Guseinov, R G; Popov, S V; Gorshkov, A N; Sivak, K V; Martov, A G

2017-12-01

To investigate experimentally ultrastructural and biochemical signs of acute injury to the renal parenchyma after warm renal ischemia of various duration and subsequent reperfusion. The experiments were performed on 44 healthy conventional female rabbits of the "Chinchilla" breed weighted 2.6-2.7 kg, which were divided into four groups. In the first, control, group included pseudo-operated animals. In the remaining three groups, an experimental model of warm ischemia of renal tissue was created, followed by a 60-minute reperfusion. The renal warm ischemia time was 30, 60 and 90 minutes in the 2nd, 3rd and 4th groups, respectively. Electron microscopy was used to study ultrastructural disturbances of the renal parenchyma. Biochemical signs of acute kidney damage were detected by measuring the following blood serum and/or urine analytes: NGAL, cystatin C, KIM-1, L-FABP, interleukin-18. The glomerular filtration was evaluated by creatinine clearance, which was determined on days 1, 5, 7, 14, 21 and 35 of follow-up. A 30-minute renal warm ischemia followed by a 60-minute reperfusion induced swelling and edema of the brush membrane, vacuolation of the cytoplasm of the endothelial cells of the proximal tubules, and microvilli restructuring. The observed disorders were reversible, and the epithelial cells retained their viability. After 60 minutes of ischemia and 60 minutes of reperfusion, the observed changes in the ultrastructure of the epithelial cells were much more pronounced, some of the epithelial cells were in a state of apoptosis. 90 min of ischemia and 60 min of reperfusion resulted in electron-microscopic signs of the mass cellular death of the tubular epithelium. Concentration in serum and/or biochemical urine markers of acute renal damage increased sharply after ischemic-reperfusion injury. Restoration of indicators was observed only in cases when the renal warm ischemia time did not exceed 60 minutes. The decrease in creatinine clearance occurred in the first 24 hours after the intervention, lasting not less than two weeks after a 30-minute warm ischemia, at least 3 weeks after a 60-minute warm ischemia and continued more than a month after a 90-minute renal artery occlusion. Intraoperative warm ischemia and subsequent reperfusion are the actual reasons for the alteration of the ultrastructure of the renal tissue and the impairment of the filtration function. The severity of the disorders depends on the duration of the damaging factors. After a 30-60-minute ischemia, the structural and functional changes in the renal tissue are reversible. The mass death of nephrocytes-effectors is possible only after warm renal ischemia longer than 60 min.

A revision of ant-mimicking spiders of the family Corinnidae (Araneae) in the Western Pacific.

PubMed

Raven, Robert J

2015-05-20

The Corinnidae of the western Pacific are revised. The formerly sparassid genus Anchognatha Thorell, 1881, and the gnaphosid genus Battalus Karsch, 1878, are transferred to the Castianeirinae. The Corinninae include only the introduced Creugas gulosus Thorell, 1878 and Medmassa christae sp. nov. from the northern Torres Strait islands. Medmassa pallipes (L. Koch, 1873) and Medmassa pusilla Simon, 1896 are newly synonymised with Creugas gulosus. The Castianeirinae from the Western Pacific including Australia includes Battalus Karsch, 1878, Copa Simon, 1886, Leichhardteus Raven & Baehr, 2013, Nyssus Walckenaer, 1805, Poecilipta Simon, 1897, and eight new genera: Disnyssus gen. nov., Iridonyssus gen. nov., Kolora gen. nov., Leptopicia gen. nov., Melanesotypus gen. nov., Nucastia gen. nov., Ozcopa gen. nov. and Ticopa gen. nov. Battalus includes B. adamparsonsi sp. nov., B. baehrae sp. nov., B. bidgemia sp. nov., B. byrneae sp. nov., B. diadens sp. nov., B. helenstarkae sp. nov., B. microspinosus sp. nov., B. rugosus sp. nov., B. spinipes Karsch, 1878, B. wallum sp. nov., B. zuytdorp sp. nov. and B. semiflavus (Simon, 1896), new combination (transferred from Medmassa). Copa, an otherwise African and Sri Lankan genus, includes C. kabana sp. nov. Disnyssus gen. nov. includes D. helenmirrenae sp. nov. and D. judidenchae sp. nov. Iridonyssus gen. nov. includes I. auripilosus sp. nov., I. formicans sp. nov., I. kohouti sp. nov. and I. leucostaurus sp. nov. Kolora gen. nov. includes K. cushingae sp. nov., K. cooloola sp. nov. and K. lynneae sp. nov., and K. sauverubens (Simon, 1896) new combination (transferred from Corinnomma Karsch, 1880). Leichhardteus includes Leichhardteus yagan sp. nov., Leichhardteus evschlingeri sp. nov., Leichhardteus strzelecki sp. nov., as well as eight recently described species. Leptopicia gen. nov. includes only Methesis bimaculata (Simon, 1896) new combination (transferred from Methesis Simon, 1896). Melanesotypus guadal gen. et sp. nov. is described from the Solomon Islands. Nucastia gen. nov., includes N. culburra sp. nov., N. eneabba sp. nov., N. muncoonie sp. nov., N. supunnoides sp. nov. and N. virewoods sp. nov.; Medmassa fusca Hogg, 1900 is transferred to Nucastia but is considered a nomen dubium. The genera Anchognatha and Supunna Simon, 1897 are junior synonyms of Nyssus, which includes Supunna albopunctatus (Hogg, 1896), Anchognatha avida Thorell, 1881, Nyssus coloripes Walckenaer, 1805, N. emu sp. nov., Agroeca insularis L. Koch, 1873 (from Fiji and the Solomon Islands), N. jaredwarden sp. nov., N. jonraveni sp. nov., N. loureedi sp. nov., N. luteofinis sp. nov., N. paradoxus sp. nov., N. pseudomaculatus sp. nov., N. robertsi sp. nov., N. semifuscus sp. nov., N. wendyae sp. nov. and N. yuggera sp. nov. Supunna funerea (Simon, 1896) and Supunna albomaculata (Rainbow, 1902) are junior synonyms of Nyssus albopunctatus; Supunna picta (L. Koch, 1873) and Storena auripes Rainbow, 1916 are junior synonyms of Nyssus coloripes Walckenaer, 1805. Ozcopa gen. nov. includes O. chiunei sp. nov., O. colloffi sp. nov., O. margotandersenae sp. nov., O. mcdonaldi sp. nov., O. monteithi sp. nov. and O. zborowskii sp. nov. Poecilipta includes P. carnarvon sp. nov., P. contorqua sp. nov., P. davidi sp. nov., P. elvis sp. nov., P. formiciforme (Rainbow, 1904) comb. nov. (transferred from Corinnomma), P. gloverae sp. nov., P. harveyi sp. nov., P. kgari sp. nov., P. samueli sp. nov., P. janthina Simon, 1896, P. kohouti sp. nov., P. lugubris sp. nov., P. marengo sp. nov., P. metallica sp. nov., P. micaelae sp. nov., P. qunats sp. nov., P. rawlinsonae sp. nov., P. ruthae Santana & Raven, sp. nov., P. smaragdinea (Simon, 1909) new combination (transferred from Supunna), P. tinda sp. nov., P. venusta Rainbow, 1904, P. waldockae sp. nov., P. wallacei sp. nov., P. yambuna sp. nov., and P. zbigniewi sp. nov. Ticopa gen. nov. includes T. australis sp. nov., T. carnarvon sp. nov., T. chinchilla sp. nov., T. dingo sp. nov., T. hudsoni sp. nov., and T. longbottomi sp. nov. For comparative purposes, males of the South-east Asian Corinnomma severum (Thorell, 1881) (the type-species) and C. javanum Simon, 1905 are figured and supplementary notes provided. Liocranum australiensis L. Koch, 1873 is transferred from Medmassa to Miturga where it is a nomen dubium. One hundred and eight species are treated in this work, of which 77 are new, 21 existing species are recognised; five existing genera are recognised, two are placed in synonymy, eight new genera are added; and one species is transferred to Miturgidae and another is listed as a nomen dubium. The Australian corinnid fauna includes 14 genera and 97 species.

Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

NASA Astrophysics Data System (ADS)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla rabbits, 11-12 months old, live weight 3.5-3.7 (n=11), Balb mice, 2-3 months old, live weight 20-22 g (n=33), Wistar rats, 3-4 months old, live weight 180-220 g(n=33). The studies were approved by the Animal Care and Use Committee for ethical animal research equivalent, at each institution. Seven rabbits, ten mice, eleven Wistar rats were vaccinated with a UV antiradiation vaccine. A second group of animals was used as biological control which received vaccine but no UV Radiation and a third group of animals was used as control without any interventions. Before and after UV Radiation, Vaccination with the UV antiradiation vaccine were provided 17 days prior to UV exposure. The animals were irradiated by a DRT-1 UV generator lamp. The dose of irradiation for laboratory, experimental animals was 10-12 * Standard Erythema Dose (SED) at L=283,7 Laboratory animals were placed in to the box with ventilation. Results: Ultraviolet irradiation of the skin was performed with high doses and causes an inflammation or erythema in all experimental animals. However the grade of skin damage and inflammation was significantly different between animals protected by vaccination and non-protected, non-vaccinated animals. Animals UV-irradiated, but who did not receive the antiradiation vaccine suffered from extensive UV skin burns of second or third degree (grade 2-3). However, animals protected with the UV antiradiation vaccine demonstrated much mild forms of skin cellular injury - mainly erythema, first degree skin burns and a few small patches with second degree skin burns (grade 1-2). Discussion: The severity of skin damage depended on area of exposed skin, time and dose of UV irradiation. Skin injury could be divided into 4 major grades: 1. Faint erythema with dry desquamation. 2. Moderate to severe erythema. 3. Severe erythema with blistering, moist desquamation. 4. Toxic epidermal necrolysis. Mild doses of UV radiation and ionizing radiation can induce cell death by apoptosis and moderate and high doses of UV and ionizing radiation induce cell death by necrosis and generate systemic inflammatory response syndrome (SIRS), toxic multiple organ injury (TMOI), toxic multiple organ dysfunction syndromes (TMODS),and finally, toxic multiple organ failure (TMOF). [D.Popov et al.2012, Fliedner T.et al. 2005, T. Azizova et al. 2004] UV-B is a complete carcinogen that is absorbed by DNA and directly damages DNA. DNA damage induced by UV-B irradiation typically includes the formation of cyclobutane pyrimidine dimmers (CPD) and 6-4 photoproducts (6-4P)[IARC, Working Group Reports, M.Saraiya et al. 2004]. The pre-vaccinated animals seem to have a blunted injury response relative to the unvaccinated animals, presumably by reduction in the inflammatory response and secondary injury effects. The mechanism of action of the antiradiation vaccine, needs further evaluation. Conclusion: A UV antiradiation vaccine appears to demonstrate efficacy as a prophylactic agent for acute solar burns and toxicity. An antiradiation UV vaccine could be used in conjunction with adjunctive measures, e.g. antioxidants and UV barriers to reduce UV radiation toxicity. The authors of this experiments would like to propose further development work of the antiradiation UV vaccine to enhance the armamentarium for prophylaxis and prevention of the various forms skin cancer.