In vivo quantitation of platelet deposition on human peripheral arterial bypass grafts using indium-111-labeled platelets. Effect of dipyridamole and aspirin

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

Pumphrey, C.W.; Chesebro, J.H.; Dewanjee, M.K.

Indium-111-labeled autologous platelets, injected 48 hours after operation, were used to evaluate the thrombogenicity of prosthetic material and the effect of platelet inhibitor therapy in vivo. Dacron double-velour (Microvel) aortofemoral artery bifurcation grafts were placed in 16 patients and unilateral polytetrafluoroethylene femoropopliteal grafts were placed in 10 patients. Half the patients in each group received platelet inhibitors before operation (dipyridamole, 100 mg 4 times a day) and after operation (dipyridamole, 75 mg, and acetylsalicylic acid, 325 mg 3 times a day); the rest of the patients served as control subjects. Five-minute scintigrams of the graft region were taken with amore » gamma camera interfaced with a computer 48, 72, and 96 hours after injection of the labeled platelets. Platelet deposition was estimated from the radioactivities of the grafts and expressed as counts per 100 pixels per microcurie injected. Dipyridamole and aspirin therapy significantly reduced the number of platelets deposited on Dacron grafts and prevented platelet accumulation over 3 days. With the small amount of platelet deposition on polytetrafluoroethylene femoropopliteal artery grafts even in control patients, platelet inhibitor therapy had no demonstrable effect on platelet deposition on these grafts. It is concluded that (1) platelet deposition on vascular grafts in vivo can be quantitated by noninvasive methods, and (2) dipyridamole and aspirin therapy reduced platelet deposition on Dacron aortofemoral artery grafts.« less

Tricuspid valve repair with Dacron band versus DeVega or segmental annuloplasty. Hospital outcome and short term results.

PubMed

Abdelgawad, Ahmed; Ramadan, Mona; Arafat, Heba; Abdel Aziz, Ahmed

2017-12-01

The purpose of this study was to compare the hospital outcome and short term results of tricuspid valve (TV) repair with three repair techniques for functional tricuspid regurgitation (TR), namely, flexible Dacron band, DeVega and segmental annuloplasty. A total of 60 patients underwent TV repair at National Heart Institute from January 2013 to November 2014, of which 20 had DeVega procedure (DV), 20 had a segmental annuloplasty (SA) procedure and 20 had a Dacron band (DB) procedure. Concomitant procedures done for rheumatic left sided valve pathology consisted of mitral valve replacement in 70% of patients, and double valve replacement in 30% of patients. Clinical and echocardiographic follow-up data were obtained. Follow-up was 100% complete and was concluded after one year. All demographic criteria and preoperative characteristics of the three studied groups were comparable except for preoperative right ventricular (RVEDD) size that was significantly bigger in Dacron band group as compared to the other two groups (3.18 ± 0.43 cm compared to 3.00 ± 0.33 cm (DV) and to 2.88 ± 0.35 cm (SA), p value of (0.045)). Similarly, all operative and postoperative criteria were comparable among the study groups. Noticeably, (RVEDD) size remodeled better postoperatively in (DB) group as compared to the other two groups, (2.54 ± 0.26 cm compared to 2.83 ± 0.311 cm (DV) and to 2.72 ± 0.29 cm (SA), mean difference values were group (0.64 ± 0.47 cm) for (DB) compared to (0.18 ± 0.29 cm) for (DV) or to (0.16 ± 0.45 cm) for (SA) with p value of 0.000. The majority of patients in each group did not have tricuspid regurgitation (TR) or mild degree (+1) of (TR) on discharge. After one year of follow-up, most of the patient had either no regurgitation or grade (+1 TR). Two patients (10%) in DV group and one patient (5%) in SA group had (+3 TR). There was no statistical significance in the incidence of hospital mortality, only one patient died in DB and one in DV group (5%) and no death happened after hospital mortality for the three groups after one year. The three techniques are options to repair the tricuspid valve, however, placement of Dacron band in patients undergoing tricuspid valve repair is associated with better RV remodelling, and hence, a probable better right ventricular performance and better outcome of repair is expected. A higher number of patients are needed with longer follow up period to appreciate the effect on survival and rate of freedom from tricuspid regurgitation and re-intervention.

Porous hydrophilic polymer: good and bad news in the orthopedic application of cruciate ligament substitution.

PubMed

Rubin, R M; Marshall, J L

1975-05-01

In the configuration used, the Hydron sponge did not enhance the ingrowth of bone into the Dacron for prosthesis anchorage. In fact, the presence of the Hydron seemed to retard such ingrowth, even though there was bony incorporation of portions of the Hydron polymer. Fixation was more rigid when Dacron was implanted bare. Hydron sponge does not appear to remain intact within a joint. It would not seem suitable for intra-articular protection of a prosthesis or local delivery of antibiotics here. We did not search further for the polymer in the regional lymph nodes. Hydron sponge is capable of eleciting an unusual phenomenon of woven bone formation. This is "good news" for its potential, but realization of such potential will certainly require additional study. Double and triple interval fluorochrome labelling would be especially helpful in further studying the localization and rate of this bone formation.

In vitro fenestration of aortic stent-grafts: implications of puncture methods for in situ fenestration durability.

PubMed

Riga, Celia V; Bicknell, Colin D; Basra, Melvinder; Hamady, Mohamad; Cheshire, Nicholas J W

2013-08-01

To investigate the quality of stent-graft fenestrations created in vitro using different needle puncture and balloon dilation angles in different commercial endografts. Fenestrations were made in a standardized fashion in 3 different endograft types: Talent monofilament twill woven polyester, Zenith multifilament tubular woven polyester, and Endofit thin-walled expanded polytetrafluoroethylene (PTFE). Punctures were made at 30°, 60°, and 90° angles using a 20-G needle and dilated using 6-mm standard and 7-mm cutting balloons; at least 6 fenestrations were made at each angle with standard balloons and at least 6 with cutting balloons. The 137 fenestrations were examined under light microscopy; quantitative and qualitative digital image analysis was performed to determine size, shape, and fenestration quality. PTFE grafts were easier to puncture/dilate, resulting in larger, elliptical fenestrations with overall better quality than the Dacron grafts; however, the puncture/dilation angle made an impact on the shape and quality of fenestrations. A significant number of fabric tears were observed in PTFE fabric at <90° puncture/dilation angles compared to Dacron grafts. In Dacron grafts, fenestration quality was significantly higher with 90° puncture/dilation angles (higher in Talent grafts). Cutting balloon use resulted in significantly more fabric tears and poor quality fenestrations in all graft types. Different endografts behave significantly differently when fenestrations are fashioned. Optimum puncture/dilation is important when considering in vivo fenestration techniques. Improvements in instrumentation, materials, and techniques are required to make this a reliable and reproducible endovascular option.

[Clinical analysis of different root treatment methods in acute Stanford type A aortic dissection].

PubMed

Xue, Y X; Zhou, Q; Pan, J; Wang, Q; Cao, H L; Fan, F D; Wang, D J

2017-04-01

Objective: To discuss the perioperative and follow-up results of different surgical methods for acute Stanford type A aortic dissection patients and analyzed the results. Methods: The clinic data of 351 acute Stanford type A aortic dissection patients received surgical therapy at Department of Thoracic and Cardiovascular Surgery, Nanjing University Medical School Affiliated Nanjing Drum Tower Hospital from January 2008 to December 2015 were analyzed retrospectively. There were 272 male and 79 female patients, aging from 22 to 83 years with a mean age of (52±13) years. According to root size, aortic valve structure and the status of dissection involvement, these patients were devided into three major groups: 218 cases with root reconstruction using Dacron felts, 34 cases with root reconstruction concomitant with aortic valve resuspension repair and 99 cases in with Bentall procedure. Proper shape based on the status of dissection involvement of Dacron patch was cut and put between the middle and outerlayer of aorta, then inside the inner layerone band Dacron felt was sutured with the aorta and the new middle layer with Dacron patch as mentioned above. In some cases the prolapsed aortic valve was re-suspended to the aortic cusp. Clinical outcomes among the 3 procedures were compared by χ(2) test, Fisher's exact test, t test and analysis of variance. Results: Cardiopulmonary bypass, cross-clamp, and circulatory arrest times of all the patients were (250±78), (171±70) and (31±10) minutes, respectively. The 30-day mortality was 9.2%(33/351), while no difference among the 3 procedures (9.6%, 8.8% and 9.1%). In the average follow-up time of (26.0±23.0) months (range from 0.5 to 90.0 months), survival rates were similar among the 3 procedures (77.7%, 77.4% and 77.8%). Only one patient received redo Bentall procedure because of severe aortic regurgitation and dilated aortic root (diameter of 50 mm). Conclusions: The indication of root management of acute Stanford type A aortic dissection is based on the diameter of aortic root, structure of aortic leaflets, and the dissection involvement. For most acute Stanford type A aortic dissection patients, aortic root reconstruction is a feasible and safe method.

Dynamic Changes of Smooth Muscle and Endothelial Markers in the Early Healing Process of Dacron Vascular Grafts in the Dog, Using RT-PCR.

PubMed

Ishida; Wu; Shi; Fujita; Sauvage; Hammond; Wijelath

2000-03-01

Previous studies of neointima formation on Dacron vascular grafts mainly focused on the late stages using immunohistochemistry staining for von Willebrand factor (vWF) and smooth muscle (SM) alpha-actin. However, it is impossible to use immunohistochemistry to study the early events of neointima formation, because graft samples lack sufficient cellular material. Therefore, we used reverse transcriptase-polymerase chain reaction (RT-PCR) to demonstrate dynamic changes of SM and endothelial markers during the early stages of neointima formation. Preclotted Dacron grafts were implanted in the descending thoracic aorta of 14 mongrel dogs. Specimens were retrieved at 1-4 weeks. Total RNAs were extracted from mid-portion of graft flow surfaces, and RT-PCR for vWF, SM myosin heavy chain (MHC), and SM alpha-actin were performed and expressed as a ratio to the ribosome s17 signal. SM MHC and vWF mRNA expression was low at 1-2 weeks but elevated at 3-4 weeks (P < 0.05). However, SM alpha-actin mRNA levels were expressed consistently throughout the study period. At 3-4 weeks, vWF mRNA expression was inversely correlated to thrombus formation on the graft flow surface. Increased expressions of SM MHC and vWF mRNA corresponded to the formation of neointima and an endothelial layer at the later stages. However, SM alpha-actin mRNA expression did not vary during the healing process. The application of RT-PCR should permit further studies of gene regulation in the early vascular graft healing process in vivo. This model can also be used to study the molecular events that are involved in SM cell differentiation.

A Circular Surgical Stapler Designed to Anastomose Aorta and Dacron Tube Graft

PubMed Central

2013-01-01

Background: A circular aortic stapler has been developed to anastomose the open end of the aorta to a size-matched Dacron tube graft in one quick motion and without having to pull sutures through the aortic wall. Methods: A prototype was developed, and its design and function were tested in bench experiments and compared with hand-sewn anastomosis. The basic design of the stapler is a central rod (anvil) surrounded by 10 stapling limbs, which can be closed over the anvil in a full circle, with staples extruded by turning a knob at the back. To test its function, a Dacron tube graft was inserted in the middle of a length of bovine aorta. One side was anastomosed with the stapler and the other hand-sewn in each of 10 experiments. Bovine blood was infused under increasing pressure. Results: It took considerably less time to complete the stapled anastomosis than the hand-sewn side (3 minutes, 46 seconds versus 15 minutes, 42 seconds). Initial leak occurred at low pressures on the hand-sewn side (mean pressure 40 mm Hg) compared with the stapled side (mean pressure 70 mm Hg). In 7 of 10 experiments, the leak became too brisk on the hand-sewn side to sustain pressure, compared with 3 of 10 with stapled anastomoses. The stapling device performed well in all cases except when the bovine aorta was too thick for the staples (two cases) or when there was a missed branch at the anastomotic site (one case). Conclusions: These experiments validate the concept and the design of this aortic stapler. There are some limitations in the current design, which will need to be modified before its use in live animals or clinically. PMID:26798678

A Circular Surgical Stapler Designed to Anastomose Aorta and Dacron Tube Graft: Validation of the Concept and Comparison to Hand-Sewn Anastomosis in Bench Experiments.

PubMed

Raza, Syed T

2013-06-01

A circular aortic stapler has been developed to anastomose the open end of the aorta to a size-matched Dacron tube graft in one quick motion and without having to pull sutures through the aortic wall. A prototype was developed, and its design and function were tested in bench experiments and compared with hand-sewn anastomosis. The basic design of the stapler is a central rod (anvil) surrounded by 10 stapling limbs, which can be closed over the anvil in a full circle, with staples extruded by turning a knob at the back. To test its function, a Dacron tube graft was inserted in the middle of a length of bovine aorta. One side was anastomosed with the stapler and the other hand-sewn in each of 10 experiments. Bovine blood was infused under increasing pressure. It took considerably less time to complete the stapled anastomosis than the hand-sewn side (3 minutes, 46 seconds versus 15 minutes, 42 seconds). Initial leak occurred at low pressures on the hand-sewn side (mean pressure 40 mm Hg) compared with the stapled side (mean pressure 70 mm Hg). In 7 of 10 experiments, the leak became too brisk on the hand-sewn side to sustain pressure, compared with 3 of 10 with stapled anastomoses. The stapling device performed well in all cases except when the bovine aorta was too thick for the staples (two cases) or when there was a missed branch at the anastomotic site (one case). These experiments validate the concept and the design of this aortic stapler. There are some limitations in the current design, which will need to be modified before its use in live animals or clinically.

[Successful treatment of injuries of the abdominal aorta].

PubMed

Merkl, J; Bat'alík, B; Mydlo, J

1990-03-01

The authors describe successful treatment of severe haemorrhagic shock caused by profuse haemorrhage from the infrarenal portion of the abdominal aorta. After primary treatment of the perforation by a vascular suture reoperation was necessary because of repeated haemorrhage from that site, and for closure of the dehiscence Dacron stitch was used.

Management of an infected aortic graft with endovascular stent grafting.

PubMed

Jamel, Sara; Attia, Rizwan; Young, Christopher

2013-01-01

Aortic graft infection, one of the most common fatal complications of aortovascular surgery, is managed mainly by the removal of infected graft material and re-establishment of vascular continuity using an extra-anatomical bypass or in situ graft replacement. Despite significant progress in perioperative, surgical, and medical treatments, the mortality and morbidity for this condition remain high. Here, we report the use of endograft implantation and prolonged intravenous antibiotics to successfully treat a life-threatening Dacron aortic tube graft infection and anastomotic leak. Although the gold standard is surgical removal of infected material and repair with a homograft, in certain extremely high-risk patients such as ours, an alternate strategy may be warranted when the risks associated with surgery are prohibitive. Endovascular repair of a surgical Dacron graft leak may provide a novel temporizing measure in the acute setting, allowing for delayed semi-urgent surgical intervention, or it may provide a definitive treatment, as in our case. At the four-year follow-up, our patient was well with a good quality of life and with no clinical, radiological, or biochemical evidence of infection.

The performance of Hancock porcine-valved Dacron conduit for right ventricular outflow tract reconstruction.

PubMed

Belli, Emre; Salihoğlu, Ece; Leobon, Bertrand; Roubertie, François; Ly, Mohammed; Roussin, Régine; Serraf, Alain

2010-01-01

The surgical reconstruction of right ventricle outflow tract (RVOT) often requires the implantation of a valved conduit. Homografts are lacking availability and are associated with limited durability in children. Our experience with the Hancock porcine-valved Dacron (DuPont, Wilmington, DE) conduit (Medtronic, Minneapolis, MN) was retrospectively assessed. Follow-up was studied in 214 survivors who underwent 247 conduit implants between January 1990 and January 2007. Pulmonary atresia/ventricular septal defect was present in 86 (40.2%) and truncus arteriosus in 62 (29%). Conduit implantation was associated with anatomic repair in 136, conduit replacement in 96, and secondary pulmonary valve insertion in 15. Median age at operation was 62.5 months (range, 1 week to 50 years), including 14 neonates (6%). Median conduit size was 17.4 mm because of routine over-sizing. Pulmonary bifurcation patch augmentation was necessary in 26 patients. Periodic echocardiography studies were performed for a median follow-up of 98 months (range, 13 to 142 months). Three (1.4%) late deaths occurred. No conduit-related deaths or complications occurred. Conduit degeneration was associated with increase in valvular gradient. Valve regurgitation was absent or mild. Higher RVOT systolic pressure gradient at discharge did not influence conduit longevity. Conduit reoperation was delayed due to percutaneous balloon dilatation in 14 patients, associated with stenting in 7. Survival with freedom from conduit reoperation was 98% (95% confidence interval [CI], 97% to 100%) at 1 year, 81% (95% CI, 75% to 87%) at 5 years, and 32% (95% CI, 22% to 42%) at 10 years. The Hancock valved conduit is a safe and reliable alternative to homografts. It appears to be appropriate in patients with limited pulmonary vascular bed and high pulmonary artery pressures. Caution is required in neonates because of the rigidity of the Dacron housing. Initial results with secondary percutaneous procedures are encouraging. 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Graft type for femoro-popliteal bypass surgery.

PubMed

Ambler, Graeme K; Twine, Christopher P

2018-02-11

Femoro-popliteal bypass is implemented to save limbs that might otherwise require amputation, in patients with ischaemic rest pain or tissue loss; and to improve walking distance in patients with severe life-limiting claudication. Contemporary practice involves grafts using autologous vein, polytetrafluoroethylene (PTFE) or Dacron as a bypass conduit. This is the second update of a Cochrane review first published in 1999 and last updated in 2010. To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro-popliteal arterial segment, for above- and below-knee femoro-popliteal bypass grafts. For this update, the Cochrane Vascular Information Specialist searched the Vascular Specialised Register (13 March 2017) and CENTRAL (2017, Issue 2). Trial registries were also searched. We included randomised trials comparing at least two different types of femoro-popliteal grafts for arterial reconstruction in patients with femoro-popliteal ischaemia. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included. Both review authors (GKA and CPT) independently screened studies, extracted data, assessed trials for risk of bias and graded the quality of the evidence using GRADE criteria. We included nineteen randomised controlled trials, with a total of 3123 patients (2547 above-knee, 576 below-knee bypass surgery). In total, nine graft types were compared (autologous vein, polytetrafluoroethylene (PTFE) with and without vein cuff, human umbilical vein (HUV), polyurethane (PUR), Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support). Studies differed in which graft types they compared and follow-up ranged from six months to 10 years.Above-knee bypassFor above-knee bypass, there was moderate-quality evidence that autologous vein grafts improve primary patency compared to prosthetic grafts by 60 months (Peto odds ratio (OR) 0.47, 95% confidence interval (CI) 0.28 to 0.80; 3 studies, 269 limbs; P = 0.005). We found low-quality evidence to suggest that this benefit translated to improved secondary patency by 60 months (Peto OR 0.41, 95% CI 0.22 to 0.74; 2 studies, 176 limbs; P = 0.003).We found no clear difference between Dacron and PTFE graft types for primary patency by 60 months (Peto OR 1.67, 95% CI 0.96 to 2.90; 2 studies, 247 limbs; low-quality evidence). We found low-quality evidence that Dacron grafts improved secondary patency over PTFE by 24 months (Peto OR 1.54, 95% CI 1.04 to 2.28; 2 studies, 528 limbs; P = 0.03), an effect which continued to 60 months in the single trial reporting this timepoint (Peto OR 2.43, 95% CI 1.31 to 4.53; 167 limbs; P = 0.005).Externally supported prosthetic grafts had inferior primary patency at 24 months when compared to unsupported prosthetic grafts (Peto OR 2.08, 95% CI 1.29 to 3.35; 2 studies, 270 limbs; P = 0.003). Secondary patency was similarly affected in the single trial reporting this outcome (Peto OR 2.25, 95% CI 1.24 to 4.07; 236 limbs; P = 0.008). No data were available for 60 months follow-up.HUV showed benefits in primary patency over PTFE at 24 months (Peto OR 4.80, 95% CI 1.76 to 13.06; 82 limbs; P = 0.002). This benefit was still seen at 60 months (Peto OR 3.75, 95% CI 1.46 to 9.62; 69 limbs; P = 0.006), but this was only compared in one trial. Results were similar for secondary patency at 24 months (Peto OR 4.01, 95% CI 1.44 to 11.17; 93 limbs) and at 60 months (Peto OR 3.87, 95% CI 1.65 to 9.05; 93 limbs).We found HBD to be superior to PTFE for primary patency at 60 months for above-knee bypass, but these results were based on a single trial (Peto OR 0.38, 95% CI 0.20 to 0.72; 146 limbs; very low-quality evidence). There was no difference in primary patency between HBD and HUV for above-knee bypass in the one small study which reported this outcome.We found only one small trial studying PUR and it showed very poor primary and secondary patency rates which were inferior to Dacron at all time points.Below-knee bypassFor bypass below the knee, we found no graft type to be superior to any other in terms of primary patency, though one trial showed improved secondary patency of HUV over PTFE at all time points to 24 months (Peto OR 3.40, 95% CI 1.45 to 7.97; 88 limbs; P = 0.005).One study compared PTFE alone to PTFE with vein cuff; very low-quality evidence indicates no effect to either primary or secondary patency at 24 months (Peto OR 1.08, 95% CI 0.58 to 2.01; 182 limbs; 2 studies; P = 0.80 and Peto OR 1.22, 95% CI 0.67 to 2.23; 181 limbs; 2 studies; P = 0.51 respectively)Limited data were available for limb survival, and those studies reporting on this outcome showed no clear difference between graft types for this outcome. Antiplatelet and anticoagulant protocols varied extensively between trials, and in some cases within trials.The overall quality of the evidence ranged from very low to moderate. Issues which affected the quality of the evidence included differences in the design of the trials, and differences in the types of grafts they compared. These differences meant we were often only able to combine and analyse small numbers of participants and this resulted in uncertainty over the true effects of the graft type used. There was moderate-quality evidence of improved long-term (60 months) primary patency for autologous vein grafts when compared to prosthetic materials for above-knee bypasses. In the long term (two to five years) there was low-quality evidence that Dacron confers a small secondary patency benefit over PTFE for above-knee bypass. Only very low-quality data exist on below-knee bypasses, so we are uncertain which graft type is best. Further randomised data are needed to ascertain whether this information translates into an improvement in limb survival.

The effect of autoclave resterilisation on polyester vascular grafts.

PubMed

Riepe, G; Whiteley, M S; Wente, A; Rogge, A; Schröder, A; Galland, R B; Imig, H

1999-11-01

polyester grafts are expensive, single-use items. Some manufacturers of uncoated, woven grafts include instructions for autoclave resterilisation to be performed at the surgeon's own request. Others warn against such manipulation. Theoretically, the glass transition point of polyester at 70-80 degrees C and the possible acceleration of hydrolysis suggest that autoclave resterilisation at 135 degrees C might be a problem. a DeBakey Soft Woven Dacron Vascular Prosthesis (Bard) and a Woven Double Velour Dacron Graft (Meadox) were autoclave-resterilised 0 to 20 times, having been weighed before and after sterilisation. Tactile testing was performed. Mechanical properties were examined by probe puncture and single-filament testing, the surface was examined by scanning electron microscopy and the degree of hydrolysis by infra-red spectroscopy. tactile testing revealed a change of feeling with increasing cycles of resterilisation. Investigation of weight, textile strength, single-filament strength, electron microscopy of the surface and infra-red spectroscopy showed no change of the material. changes felt are presumably a surface phenomenon, not measurably affecting strength or chemistry of material after autoclave resterilisation. We therefore feel that it is safe to use once-autoclave-resterilised surplus uncoated polyester grafts, provided that sterility is guaranteed. Copyright 1999 Harcourt Publishers Ltd.

Biocompatibility tests of components of an implantable cardiac assist device.

PubMed

von Recum, A F; Imamura, H; Freed, P S; Kantrowitz, A; Chen, S T; Ekstrom, M E; Baechler, C A; Barnhart, M I

1978-09-01

A permanently implantable in-series left ventricular assist device, the dynamic aortic patch (DAP), has been tested in chronic animal experiments. The DAP replaces a section of the intrathoracic aortic wall. Hemothorax and hematocele at the implantation site have been complications in recent experiments. Primary postoperative hemorrhage was ruled out, and the biocompatibility of all components was therefore examined. Dacron velour, Teflon felt, conductive polyurethane, segmented polyether polyurethane, and Teflon-coated polyester fiber sutures were implanted in the pleural cavities of dogs and tested in vitro by culturing canine saphenous vein explants on them. In vivo experiments demonstrated that all components elicited mild to moderate inflammatory reactions, but hematocele occurred only when the components were implanted in the aorta with direct blood contact and exposed to arterial blood pressures. In vitro, cells were cultured on all components with no signs of toxic reactions. These results indicated that the host tolerated all implant components without major inflammatory responses. However, histological data indicated that chronic slow bleeding into or through the Dacron velour in contact with the arterial blood serum could account for hemothorax or hematocele formation. Therefore, a configuration of the assist device using materials impermeable to blood may obviate these difficulties.

Paresev 1-A on lakebed with tow plane

NASA Image and Video Library

1962-08-24

The Paresev 1-A (Paraglider Research Vehicle) and the tow airplane, 450-hp Stearman sport Biplane, sitting on Rogers dry lakebed, Edwards, California. The control system in the Paresev 1-A had a more conventional control stick position and was cable-operated; the main landing gear used shocks and bungees with the 100-square-foot wing membrane being made of 6-ounce unsealed Dacron.

Paresev 1-A on lakebed with tow plane

NASA Technical Reports Server (NTRS)

1962-01-01

The Paresev 1-A (Paraglider Research Vehicle) and the tow airplane, 450-hp Stearman sport Biplane, sitting on Rogers dry lakebed, Edwards, California. The control system in the Paresev 1-A had a more conventional control stick position and was cable-operated; the main landing gear used shocks and bungees with the 150-square-foot wing membrane being made of 6-ounce unsealed Dacron.

Aortic Root Reconstruction with a New Dacron Graft Featuring Prefabricated Coronary Side Branches

PubMed Central

Calcaterra, Domenico; Jazayeri, Mohammad-Ali; Turek, Joseph W.; Parekh, Kalpaj R.; Bashir, Mohammad; Karam, Karam; Farivar, Robert S.

2017-01-01

Background Coronary button reimplantation can represent a technical challenge of aortic root reconstruction that can be associated with significant morbidity and mortality. With the goal of simplifying coronary reimplantation and reducing the incidence of related complications, we designed a new Dacron graft with prefabricated coronary branches to minimize coronary artery mobilization and prevent the potential mechanical complications of reattachment to the body of the graft. Methods Between June 2010 and May 2012, we implanted the graft in eight patients (six males, two females) ranging in age from 42-68 years (mean, 54 years). Six procedures were modified Bentall reconstructions, and two procedures were valve-sparing root replacements using the reimplantation technique. Results There were no complications and no morbidity or mortality related to coronary reattachment. All patients were alive and doing well at a mean follow-up of 26 months (range, 17-38 months). At an extended mean follow-up of 42 months (range, 25-56 months), one patient died of stroke-related complications. No radiologic or clinical evidence of impairment of coronary perfusion was identified in any patient. Conclusions The use of this new graft model may simplify the technique of root reconstruction and potentially lower the incidence of mechanical complications related to coronary button reimplantation. PMID:28868309

Epithelioid Angiosarcoma With Metastatic Disease After Endovascular Therapy of Abdominal Aortic Aneurysm

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

Schmehl, Joerg, E-mail: joerg.schmehl@med.uni-tuebingen.de; Scharpf, Marcus; Brechtel, Klaus

2012-02-15

Malignancies of the aortic wall represent a rare condition, and only a few reports have covered cases of sarcomas arising at the site of a prosthesis made of Dacron. A coincidence with endovascular repair has only been reported in one case to date. We report a patient with epithelioid angiosarcoma and metastatic disease, which was found in an aneurysmal sac after endovascular aortic repair for abdominal aortic aneurysm.

Infrarenal aorta as the donor site for bypasses to the superior mesenteric artery for chronic mesenteric ischemia: A prospective clinical series of 24 patients.

PubMed

Illuminati, Giulio; Pizzardi, Giulia; Calio', Francesco G; Pasqua, Rocco; Masci, Federica; Vietri, Francesco

2017-11-01

Treatment of symptomatic, chronic mesenteric ischemia is indicated to relieve symptoms and prevent acute ischemia and death. Current therapeutic options include endovascular and open surgery. The purpose of this prospective study was to evaluate the results of bypasses to the superior mesenteric artery arising from the infrarenal aorta or infrarenal aortic grafts. From January 1999 to December 2016, 24 consecutive patients with a mean age of 61 years underwent a prosthetic bypass to the superior mesenteric artery. Nine patients (37%) presented with an associated clinically important stenosis of the celiac artery and 10 (42%) of the inferior mesenteric artery. Five patients (21%) received preoperative parenteral nutrition. Four patients (17%) underwent dual antiplatelet treatment. The donor site was the infrarenal aorta in 19 patients (79%) and an infrarenal, Dacron graft was used in 5 (21%). The origin of the bypass was from the distal infrarenal aorta or Dacron graft in 19 patients (79%) and from the proximal infrarenal aorta in 5 patients (21%). The graft material consisted of 7 mm polytetrafluoroethylene in 19 cases (79%) and 7 mm Dacron in 5 cases (21%). A concomitant bypass to the inferior mesenteric artery was performed in 4 patients (17%). The primary end points were postoperative mortality, morbidity, graft infection, late survival, primary patency, and symptom-free rate. The secondary end point was postoperative hemorrhagic complications. No postoperative mortality occurred. Postoperative morbidity included a prolonged postoperative ileus in 4 patients (17%), transitory postoperative increases in serum creatinine concentrations in 3 patients (12%), and myocardial ischemia in 2 patients (8%). No postoperative hemorrhagic complications or graft infection were observed. Overall, the cumulative survival rate was 77% at 60 months. The overall late-patency rate and freedom from recurrence of symptoms were both 87% at 60 months. Infrarenal aorta and infrarenal aortic grafts are an excellent source for the revascularization of the superior mesenteric artery. Bypasses to the superior mesenteric artery from the infrarenal aorta, either isolated or associated with adjunctive bypass to the inferior mesenteric artery, yield results that are comparable with those obtained with complete digestive artery revascularization using other donor sources. Copyright © 2017 Elsevier Inc. All rights reserved.

Percutaneous coronary angioplasty of a left anterior descending artery implanted on a Dacron coronary prosthesis on an aortic conduit.

PubMed

Drobinski, G; Thomas, D; Funck, F; Metzger, J P; Canny, M; Grosgogeat, Y

1986-08-01

Certain surgical techniques may make it difficult to catheterize the coronary ostia and perform percutaneous coronary angioplasty. We report the case of a 48 year old patient who developed unstable angina four years after a Bentall's procedure with reimplantation of the coronary arteries on a Dacron coronary prosthesis. The anginal pain was related to very severe stenosis of the proximal segment of the left anterior descending artery. The difficulties encountered during the dilatation procedure were due to: (a) the ectopic position of the ostium of the prosthesis on the anterior aortic wall; (b) the forces exerted on the aortic prosthesis wall and on the valvular prosthesis during positioning of the guiding catheter which were poorly tolerated and induced a vagal reaction; (c) the direction taken by the distal tip of the guiding catheter, perpendicular to the wall of the aortic prosthesis; (d) the sinuosity of the arterial trajectory: the left coronary segment of the coronary prosthesis was directed towards the left circumflex artery rather than towards the left anterior descending artery. Coronary angioplasty succeeded after relatively complex technical procedures: special guiding catheter, unusual intra-aortic manoeuvres for positioning the guiding catheter, dilatation catheter change on a 3-metre long guide wire in order to cross the stenotic segment; this was performed with a super low-profiled dilatation catheter. There were no complications and anginal pain disappeared.

Assessment of Superstructure Ice Protection as Applied to Offshore Oil Operations Safety: Problems, Hazards, Needs, and Potential Transfer Technologies

DTIC Science & Technology

2008-09-01

thermostats, or materials such as carbon layers, which vary in thickness with location and are self - healing and self - regulating. Ships commonly use heating...aircraft today. Pneumatic deicing systems consist of rubber or other elastomeric boots placed on the leading edge of an aircraft wing or on any surface...by Kenney, two as- semblies consisting of neoprene rubber and urethane-coated Dacron fabric were hung from bulkheads where icing would occur. A timer

Wearable Triboelectric Generator for Powering the Portable Electronic Devices.

PubMed

Cui, Nuanyang; Liu, Jinmei; Gu, Long; Bai, Suo; Chen, Xiaobo; Qin, Yong

2015-08-26

A cloth-base wearable triboelectric nanogenerator made of nylon and Dacron fabric was fabricated for harvesting body motion energy. Through the friction between forearm and human body, the generator can turn the mechanical energy of an arm swing into electric energy and power an electroluminescent tubelike lamp easily. The maximum output current and voltage of the generator reach up to 0.2 mA and 2 kV. Furthermore, this generator can be easily folded, kneaded, and cleaned like a common garment.

In vitro investigation of a novel elastic vascular prosthesis for valve-sparing aortic root and ascending aorta replacement.

PubMed

Scharfschwerdt, Michael; Leonhard, Moritz; Lehmann, Judith; Richardt, Doreen; Goldmann, Helmut; Sievers, Hans-Hinrich

2016-05-01

Prosthetic replacement of the thoracic aorta with common Dacron prostheses impairs the aortic 'windkessel' and, in valve-sparing procedures, also aortic valve function. Elastic graft material may overcome these deficiencies. Fresh porcine aortas including the root were set up in a mock circulation before and after replacement of the ascending part with a novel vascular prosthesis providing elastic behaviours. In a first series (n = 14), haemodynamics and leaflet motions of the aortic valve were investigated and also cyclic changes of aortic dimensions at different levels of the root. In a second series (n = 7), intravascular pressure and dimensions of the proximal descending aorta were measured and the corresponding wall tension was calculated. Haemodynamics of the aortic valve remain comparable after replacement. Though the novel prosthesis does not feature such high distensibility as the native aorta, the dynamic of the root was significantly increased compared with common Dacron prostheses at the commissural level, preserving 'windkessel' function. Thus, wall tension of the residual aorta remained unchanged; nevertheless, maximum pressure-time differential dp/dt increased by 13%. The use of the novel elastic prosthesis for replacement of the ascending aorta seems to be beneficial, especially with regard to the preservation of the aortic windkessel. Further studies will be needed to clarify long-term utilization of the material in vivo. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Cryogenic insulation development

NASA Technical Reports Server (NTRS)

Leonhard, K. E.

1972-01-01

Multilayer insulations for long term cryogenic storage are described. The development effort resulted in an insulation concept using lightweight radiation shields, separated by low conductive Dacron fiber tufts. The insulation is usually referred to as Superfloc. The fiber tufts are arranged in a triangular pattern and stand about .040 in. above the radiation shield base. Thermal and structural evaluation of Superfloc indicated that this material is a strong candidate for the development of high performance thermal protection systems because of its high strength, purge gas evacuation capability during boost, its density control and easy application to a tank.

The effect of configuration on strength, durability, and handle of Kevlar fabric-based materials

NASA Technical Reports Server (NTRS)

Reuter, L. L.; Munson, J. B.

1977-01-01

Five Kevlar based laminates and three Kevlar based coated materials were designed, hand made, and tested against comparative conventional Dacron based materials for strength, peel, tear, puncture, creases, and handle. Emphasis was placed on evaluating geometric orientation of constituents, use of elastomeric film in place of high modulus films, and the use of flying thread loom bias reinforcement of Kevlar yarns. Whereas, the performance of the Kevlar laminates was severely degraded by crease effects, significant gains in overall performance factors were shown for the coated Kevlar materials.

3D Printing to Model Surgical Repair of Complex Congenitally Corrected Transposition of the Great Arteries.

PubMed

Sahayaraj, R Anto; Ramanan, Sowmya; Subramanyan, Raghavan; Cherian, Kotturathu Mammen

2017-01-01

We report the use of three-dimensional (3D) modeling to plan surgery for physiologic repair of congenitally corrected transposition of the great arteries with pulmonary atresia, dextrocardia, and complex intra cardiac anatomy. Based on measurements made from the 3D printed model of the actual patient's anatomy, we anticipated using a composite valved conduit (Dacron tube graft, decellularized bovine jugular vein, and aortic homograft) to establish left ventricle-to-pulmonary artery continuity with relief of stenosis involving the pulmonary artery confluence and bilateral branch pulmonary arteries.

Investigation of Kevlar fabric-based materials for use with inflatable structures

NASA Technical Reports Server (NTRS)

Niccum, R. J.; Munson, J. B.; Rueter, L. L.

1977-01-01

Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported. The practicality of using Kevlar in aerostat materials is demonstrated, and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar-based materials are compared with conventional Dacron-reinforced counterparts. A comprehensive test and qualification program is discussed, and considerable quantitative biaxial tensile and shear test data are provided.

Conduit repair for complex congenital heart disease with pulmonary atresia or right ventricular outflow tract obstruction. Part II: early and late hemodynamic and echocardiographic findings.

PubMed

Rupprath, G; Vogt, J; de Vivie, E R; Beuren, A J

1981-12-01

The results are presented of 44 systematic cardiac catheterizations in 35 patients after successful repair of various types of congenital cyanotic heart disease using a conduit. The operations were performed from 1972 to 1981. The patients were followed from 6 months to 9 years, the mean interval between operation and catheterization was 2.5 years (4 weeks to 8 years). Different types of conduits were used: a Hancock conduit in 27 cases (1 replaced), an aortic homograft in 3 cases (all 3 replaced by a Hancock conduit), a Dacron tube with Lillehei-Kaster valve in 2 cases (1 replaced), a lonescu-Shiley conduit in 5 cases, a composite graft of pericardium and a Hancock valve in one patient (replaced) and a valveless Dacron tube in one patient. The total conduit gradient was differentiated in 43/44 investigations. For the Hancock conduit the mean proximal gradient was 9 mmHg, the valvular 14 and the distal 13 mmHg. Severe valvular stenosis of the porcine valve occurred in 3 patients. For the lonescu-Shiley conduit only early, but promising, results are available. Three of the 35 patients died late (2.5 and 4 years postoperatively); the deaths were related to severe additional lesions. Cross-sectional echocardiography was performed in 32 of the 35 patients. The latter does not appear to be a reliable method for the detection of valvular lesions so far, but is helpful for the diagnosis of proximal and distal obstructions of the conduit.

Long-Term Survival and Freedom From Reoperation After Placement of a Pulmonary Xenograft Valved Conduit.

PubMed

Alfieris, George M; Swartz, Michael F; Lehoux, Juan; Bove, Edward L

2016-08-01

The optimal choice for pulmonary valve replacement (PVR) remains controversial. This study hypothesized that xenografts used for PVR would result in prolonged long-term survival and freedom from reoperation. Children and adults with congenital heart disease requiring PVR using a xenograft from 1980 to 1985 were reviewed. In all cases, the xenograft valve was either sewn or manufactured into a Dacron conduit, and the conduit was sewn to the pulmonary artery bifurcation. Clinical data were analyzed, and survival and freedom from reoperation were determined using Kaplan-Meier analysis. Twenty-four patients received a xenograft for PVR at 14.6 ± 5.6 years. Conduit size ranged from 21 to 27 mm. Most patients received a Carpentier-Edwards valved conduit (n = 17), followed by a Hancock valved conduit (n = 5) and an Ionescu-Shiley valve sewn into a Dacron graft (n = 2). No perioperative deaths occurred. Reoperation was required mainly for pulmonary stenosis (72.7%), followed by pulmonary insufficiency (18.2%), or both stenosis and insufficiency (9%). Freedom from reoperation was 90%, 56%, 43%, and 14% at 10, 20, 25, and 30 years, respectively. At most recent follow-up the was only death, which was related to severe biventricular failure 25 years after conduit implant. PVR using a xenograft valved conduit results in prolonged freedom from reoperation and excellent long-term survival. These data, which provide long-term follow-up information on xenograft valves after PVR. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Laser-Raman microprobe identification of inclusions in capsules associated with silicone gel breast implants.

PubMed

Centeno, J A; Mullick, F G; Panos, R G; Miller, F W; Valenzuela-Espinoza, A

1999-07-01

Raman spectroscopy (the analysis of scattered photons after excitation with a monochromatic light source) provides a nondestructive method for identifying organic and inorganic materials on the basis of the molecule's characteristic spectrum of vibrational frequencies. Although the technique has been predominantly applied in sciences other than pathology, the recent advent of high-quality microscope optics coupled to optical Raman spectrometers (a variation known as a Raman microprobe) rendered this technique amenable to applications in human pathology. In the Raman microprobe, a laser beam is focused on a spot approximately 1 microm in diameter on the surface of the sample, e.g., tissue, and the scattered light is collected and analyzed. In this investigation, we used the Raman microprobe for the identification of foreign materials in breast implant capsular tissues. The characteristic silicone group frequencies associated with the silicon-oxygen stretch, the silicone-carbon stretch, the silicon-methyl and the methyl carbon-hydrogen stretch frequencies were used to identify polydimethylsiloxane and to define chemical differences among the various other implant-related inclusions. All of the inclusions were positively identified in a series of 44 capsules from silicone gel-filled implants: polydimethylsiloxane was found in 44 of 44 capsules surrounding silicone gel-filled implants; polyurethane was seen in 4 of 4 capsules around polyurethane foam-coated gel-filled implants; 4 of 4 capsules enveloping Dacron patch gel-filled implants revealed Dacron; and talc was identified in 8 of these 44 capsules. Raman microspectroscopy provides a rapid, accurate, and sensitive method for identifying inclusions associated with silicone and other implant materials in tissue.

The use of a stentless porcine bioprosthesis to repair an ascending aortic aneurysm in combination with aortic valve regurgitation.

PubMed Central

Akpinar, B; Sanisoğlu, I; Konuralp, C; Akay, H; Güden, M; Sönmez, B

1999-01-01

Over the years, many surgical methods have evolved for the treatment of ascending aortic aneurysm in combination with aortic valve regurgitation; however, precise guidelines for optimal surgical techniques for varying presentations have not been defined. We describe the use of a stentless porcine bioprosthesis (Medtronic Freestyle) in a patient with an ascending aortic aneurysm and aortic regurgitation. We used the complete root replacement method, and anastomosed a Dacron graft (Hemashield) between the bioprosthetic valve and the native aorta to replace the distal part of the aneurysm. Images PMID:10524742

Hyaluronic acid enhancement of expanded polytetrafluoroethylene for small diameter vascular grafts

NASA Astrophysics Data System (ADS)

Lewis, Nicole R.

Cardiovascular disease is the leading cause of mortality and morbidity in the United States and other developed countries. In the United States alone, 8 million people are diagnosed with peripheral arterial disease per year and over 250,000 patients have coronary bypass surgery each year. Autologous blood vessels are the standard graft used in small diameter (<6mm) arterial bypass procedures. Synthetic small diameter grafts have had limited success. While polyethylene (Dacron) and expanded polytetrafluoroethylene (ePTFE) are the most commonly used small diameter synthetic vascular graft materials, there are significant limitations that make these materials unfavorable for use in the low blood flow conditions of the small diameter arteries. Specifically, Dacron and ePTFE grafts display failure due to early thrombosis or late intimal hyperplasia. With the shortage of tissue donors and the limited supply of autologous blood vessels available, there is a need for a small diameter synthetic vascular graft alternative. The aim of this research is to create and characterize ePTFE grafts prepared with hyaluronic acid (HA), evaluate thrombogenic potential of ePTFE-HA grafts, and evaluate graft mechanical properties and coating durability. The results in this work indicate the successful production of ePTFE-HA materials using a solvent infiltration technique. Surface interactions with blood show increased platelet adhesion on HA-modified surfaces, though evidence may suggest less platelet activation and erythrocyte lysis. Significant changes in mechanical properties of HA-modified ePTFE materials were observed. Further investigation into solvent selection, uniformity of HA, endothelialization, and dynamic flow testing would be beneficial in the evaluation of these materials for use in small diameter vascular graft bypass procedures.

The treatment of chronic intestinal ischemia.

PubMed

Illuminati, G; Caliò, F G; D'Urso, A; Papaspyropoulos, V; Mancini, P; Ceccanei, G; Vietri, F

2004-01-01

Due to the rarity of the condition, large and prospective series defining the optimal method of digestive arteries revascularization, for the treatment of chronic intestinal ischemia, are lacking. The aim of this consecutive sample clinical study was to test the hypothesis that flexible application of different revascularization methods, according to individual cases, will yield the best results in the management of chronic intestinal ischemia. Eleven patients, of a mean age of 57 years, underwent revascularization of 11 digestive arteries for symptomatic chronic mesenteric occlusive disease. Eleven superior mesenteric arteries and one celiac axis were revascularized. The revascularization techniques included retrograde bypass grafting in 7 cases, antegrade bypass grafting in 2, percutaneous arterial angioplasty in 1, and arterial reimplantation in one case. The donor axis for either reimplantation or bypass grafting was the infrarenal aorta in 4 cases, an infrarenal Dacron graft in 4, and the celiac aorta in one case. Grafting materials included 5 polytetrafluoroethylene (PTFE) and 3 Dacron grafts. Concomitant procedures included 3 aorto-ilio-femoral grafts and one renal artery revascularization. Mean follow-up length was 31 months. There was no operative mortality. Cumulative survival rate was 88.9% at 36 months (SE 12.1%). Primary patency rate was 90% at 36 months (SE 11.6%). The symptom free rate was 90% at 36 months (SE 11.6%). Direct reimplantation, antegrade and retrograde bypass grafting, all allow good mid-term results: the choice of the optimal method depends on the anatomic and general patients status. Associated infrarenal and renal arterial lesions can be safely treated in the same time of digestive revascularization. Angioplasty alone yields poor results and should be limited to patients at poor risk for surgery.

The surgical treatment of chronic intestinal ischemia: results of a recent series.

PubMed

Illuminati, G; Caliò, F G; D'Urso, A; Papaspiropoulos, V; Mancini, P; Ceccanei, G

2004-04-01

Due to the rarity of the condition, large and prospective series defining the optimal method of digestive arteries revascularization, for the treatment of chronic intestinal ischemia, are lacking. The aim of this consecutive sample clinical study was to test the hypothesis that flexible application of different revascularization methods, according to individual cases, will yield the best results in the management of chronic intestinal ischemia. Eleven patients, of a mean age of 56 years, underwent revascularization of 11 digestive arteries for symptomatic chronic mesenteric occlusive disease. Eleven superior mesenteric arteries and one celiac axis were revascularized. The revascularization techniques included retrograde bypass grafting in 7 cases, antegrade bypass grafting in 2, percutaneous arterial angioplasty in 1, and arterial reimplantation in one case. The donor axis for either reimplantation or bypass grafting was the infrarenal aorta in 4 cases, an infrarenal Dacron graft in 4, and the celiac aorta in one case. Grafting materials included 5 polytetrafluoroethylene (PTFE) and 3 Dacron grafts. Concomitant procedures included 3 aorto-ilio-femoral grafts and one renal artery revascularization. Mean follow-up duration was 31 months. There was no operative mortality. Cumulative survival rate was 88.9% at 36 months (SE 12.1%). Primary patency rate was 90% at 36 months (SE 11.6%). The symptom free rate was 90% at 36 months (SE 11.6%). Direct reimplantation, antegrade and retrograde bypass grafting, all allow good mid-term results: the choice of the optimal method depends on the anatomic and general patient's status. Associated infrarenal and renal arterial lesions can be safely treated in the same time of digestive revascularization. Angioplasty alone yields poor results and should be limited to patients at poor risk for surgery.

The making of indigenous vascular prosthesis

PubMed Central

Unnikrishnan, Madathipat; Viswanathan, Sidharth; Balasubramaniam, K.; Muraleedharan, C.V.; Lal, Arthur Vijayan; Mohanan, P.V.; Mohanty, Meera; Kapilamoorthy, Tirur Raman

2016-01-01

Background & objectives: Vascular illnesses are on the rise in India, due to increase in lifestyle diseases and demographic transition, requiring intervention to save life, organ or limbs using vascular prosthesis. The aim of this study was to develop indigenous large diameter vascular graft for treatment of patients with vascular pathologies. Methods: The South India Textile Research Association, at Coimbatore, Tamil Nadu, India, developed seamless woven polyester (Polyethylene terephthalate) graft at its research wing. Further characterization and testing followed by clinical trials were conducted at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fifteen in vivo experiments were carried out in 1992-1994 in pigs as animal model. Controlled (phase I) clinical trial in ten patients was performed along with control graft. Thereafter, phase II trial involved 22 patients who underwent multi-centre clinical trial in four centres across India. Results: Laboratory testing showed that polyester graft was non-toxic, non-leeching and non-haemolytic with preserved long-term quality, further confirming in pigs by implanting in thoracic aorta, comparable to control Dacron grafts. Perigraft incorporation and smooth neointima formation which are prime features of excellent healing characteristics, were noted at explantation at planned intervals. Subsequently in the phase I and II clinical trials, all patients had excellent recovery without mortality or device-related adverse events. Patients receiving the test graft were followed up for 10 and 5 years, respectively. Serial clinical, duplex scans and CT angiograms performed periodically confirmed excellent graft performance. Interpretation & conclusions: Indigenously developed Chitra vascular graft was comparable to commercially available Dacron graft, ready for clinical use at affordable cost to patients as against costly imported grafts. PMID:27748302

Correction of anterior mitral prolapse: the parachute technique.

PubMed

Zannis, Konstantinos; Mitchell-Heggs, Laurens; Di Nitto, Valentina; Kirsch, Matthias E W; Noghin, Milena; Ghorayeb, Gabriel; Lessana, Arrigo

2012-04-01

To evaluate a new surgical technique for the correction of anterior mitral leaflet prolapse. From October 2006 to November 2011, 44 consecutive patients (28 males, mean age 55 ± 13 years) underwent mitral valve repair because of anterior mitral leaflet prolapse. Echocardiography was performed to evaluate the distance from the tip of each papillary muscle to the annular plane. A specially designed caliper was used to manufacture a parachute-like device, by looping a 4-0 polytetrafluoroethylene suture between a Dacron strip and Teflon felt pledget, according to the preoperative echocardiographic measurements. This parachute was then used to resuspend the anterior mitral leaflet to the corresponding papillary muscle. Of the 44 patients, 35 (80%) required concomitant posterior leaflet repair. Additional procedures were required in 16 patients (36%). The preoperative logistic European System for Cardiac Operative Risk Evaluation was 4.3 ± 6.9. The clinical and echocardiographic follow-up were complete. The total follow-up was 1031 patient-months and averaged 23.4 ± 17.2 months per patient. The overall mortality rate was 4.5% (n = 2). Also, 2 patients (4.5%) with recurrent mitral regurgitation required mitral valve replacement, 1 on the first postoperative day and 1 after 13 months. In the latter patient, histologic analysis showed complete endothelialization of the Dacron strip. At follow-up, all non-reoperated survivors (n = 40) were in New York Heart Association class I, with no regurgitation in 40 patients (93%) and grade 2+ mitral regurgitation in 3 (7%). This technique offers a simple and reproducible solution for correction of anterior leaflet prolapse. Echocardiography can reliably evaluate the length of the chordae. However, the long-term results must be evaluated and compared with other surgical strategies. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Long-term follow-up of saphenous vein, internal jugular vein, and knitted Dacron patches for carotid artery endarterectomy.

PubMed

Jacobowitz, G R; Kalish, J A; Lee, A M; Adelman, M A; Riles, T S; Landis, R

2001-05-01

To determine whether choice of material used for patch closure following carotid artery endarterectomy (CAE) influences rates of early or late restenosis, stroke, and death, 274 consecutive CAEs were retrospectively reviewed. Saphenous vein (SV) was used in 159 (58.0%) procedures; everted, double-thickness jugular vein (JV) was used in 25 (9.1%); and knitted Dacron (KD) was used in 90 (32.9%). Primary closure was not used in this series. There were four perioperative strokes: two (1.3%) in SV, one (4%) in JV, and one (1.1%) in KD (NS). Follow-up was obtained on 263 (96%) operated arteries (mean 41.5 months). Duplex scan results were available for 236 (89.7%) of these arteries (mean follow-up time 33.7 months). There were three (2%) late strokes in SV and two (2.2%) in KD (NS). In long-term follow-up, one patient (0.7%) in SV and two (2.4%) in KD developed > 80% stenosis (NS). One patient (0.7%) in SV, one (5.3%) in JV, and one (1.2%) in KD had total occlusion of the operated vessel (NS). Three procedures (2.2%) in SV, 1 (5.3%) in JV, and 7 (8.5%) in KD demonstrated moderate stenosis (50-79%) (NS). Three-year follow-up shows that choice of patch material does not affect early or late stroke rate, stroke-related death rate, rate of high-grade (> 80%) restenosis, or rate of total occlusion. There is a higher incidence of moderate stenosis in KD. Although our results and a review of the literature do not indicate that these patients are at increased risk for symptoms or progression of stenosis, they should be followed by duplex scanning to ensure that this is the case.

Attitudes towards cytology and human papillomavirus self-sample collection for cervical screening among Hindu women in London, UK: a mixed methods study

PubMed Central

Cadman, Louise; Ashdown-Barr, Lesley; Waller, Jo; Szarewski, Anne

2015-01-01

Objectives To explore the attitudes, views and understanding of women attending a Hindu temple in London, UK towards cervical screening, human papillomavirus (HPV) testing and two HPV self-sample collection devices: the Dacron swab and Evalyn® brush. Methods A mixed methods design comprising a survey and four focus groups was adopted. Focus group discussions were recorded and transcribed verbatim and explored using thematic framework analysis. Results A total of 185 Hindu women completed surveys and 23 attended focus groups. Of the respondents 75% aged 25–64 years reported having cervical screening within the last 5 years; 85% had attended college or university. Familiar barriers to attendance for screening were identified: fear of pain and the test result, embarrassment, screener's attitude, inconvenient appointment times and difficulty with child care. Additional barriers cited included age and country of birth, with older and Indian-born women thought to be less likely to attend for screening. Self-collected sampling had a mixed reception. Women were not confident that their sample would be as good as a clinician sample and expressed concern about the impact that a positive HPV result might have on their relationships. Conclusions Screening attendance in this highly educated group of Hindu women was slightly lower than in the general population (75% of women aged 25–64 years had been screened in the last 5 years compared with 79% in England as a whole). Familiar barriers to screening were identified. Women felt able to collect their own sample for HPV testing with a Dacron swab but lacked confidence that it would be as good as that obtained by a clinician. PMID:24521934

Combined open proximal and stent-graft distal repair for distal arch aneurysms: an alternative to total debranching.

PubMed

Zierer, Andreas; Sanchez, Luis A; Moon, Marc R

2009-07-01

We present herein a novel, combined, simultaneous open proximal and stent-graft distal repair for complex distal aortic arch aneurysms involving the descending aorta. In the first surgical step, the transverse arch is opened during selective antegrade cerebral perfusion, and a Dacron graft (DuPont, Wilmington, DE) is positioned down the descending aorta in an elephant trunk-like fashion with its proximal free margin sutured circumferentially to the aorta just distal to the left subclavian or left common carotid artery. With the graft serving as the new proximal landing zone, subsequent endovascular repair is performed antegrade during rewarming through the ascending aorta.

[Graft Pseudoaneurysm after Ascending to Abdominal Aorta Bypass for Atypical Coarctation Due to Aortitis Syndrome;Report of a Case].

PubMed

Yada, Masashi; Yamanaka, Kazuo; Miwa, Senri; Hirose, Keiichi; Sakaguchi, Hisashi; Yoshida, Yukiyo; Onga, Youhei; Tara, Yuichi

2017-05-01

We present a case of a 44-year-old woman, with pseudoaneurysm formation at the middle of the prosthetic graft, 60 mm in diameter. She had been diagnosed with atypical coarctation due to aortitis 27 years before, and had undergone a bypass operation with 14 mm-diameter Cooley double velour graft from the ascending aorta to the abdominal aorta. This time, endovascular aortic repair was performed to prevent rupture of the pseudoaneurysm. Though a knitted Dacron graft has a risk of psuedaneurysm formation long patency could be obtained when used in ascending aorta-abdominal aorta bypass.

Bilateral External Iliac Artery Dissection in a Middle-Aged Male Athlete

PubMed Central

Yamanaka, Yasushi; Yoshida, Tetsuya; Nagaoka, Eiki

2017-01-01

We present the case of a bilateral external iliac artery (EIA) dissection in a 44-year-old male athlete. The patient was referred to our department for right lower abdominal pain without claudication during single squatting. His athletic history included participation in approximately five athletic events per year. Contrast-enhanced computed tomography (CT) revealed bilateral EIA dissection and right renal infarction. Following medical treatment for his hypertension and considering his medical history, a bilateral EIA replacement with 8-mm Dacron straight grafts was performed on the 24th day after hospital admission. Postoperative contrast-enhanced CT revealed good bilateral graft patency and perfusion following surgery. PMID:29515713

Bilateral External Iliac Artery Dissection in a Middle-Aged Male Athlete.

PubMed

Yamanaka, Yasushi; Yoshida, Tetsuya; Nagaoka, Eiki

2017-12-25

We present the case of a bilateral external iliac artery (EIA) dissection in a 44-year-old male athlete. The patient was referred to our department for right lower abdominal pain without claudication during single squatting. His athletic history included participation in approximately five athletic events per year. Contrast-enhanced computed tomography (CT) revealed bilateral EIA dissection and right renal infarction. Following medical treatment for his hypertension and considering his medical history, a bilateral EIA replacement with 8-mm Dacron straight grafts was performed on the 24th day after hospital admission. Postoperative contrast-enhanced CT revealed good bilateral graft patency and perfusion following surgery.

Dewar technology study

NASA Technical Reports Server (NTRS)

Davis, W.

1975-01-01

The development of a Dewar system for handling liquid helium under weightless conditions is described. Porous plug designs for the prevention of superfluid creep out of the dewar through the vent line were evaluated. For the purpose of designing a neck to provide a transition from the cold cavity to the outside, the loads carried by the neck and equipment supports were studied. Temperature, pressure, and mass flow instrumentation for monitoring Dewar performance were also evaluated. In addition, multilayer blankets consisting of aluminized Mylar separated by Dacron net sheets were designed to insulate the pressure vessel. The dewar system is suggested for use with the star tracking telescope aboard the relativity satellite.

Modified edge-to-edge technique for correction of congenital mitral regurgitation in infants and children.

PubMed

Zhang, Gang; Zhang, Fusheng; Zhu, Mei; Zhang, Wenlong; Fan, Quanxin; Zou, Chengwei; Wang, Anbiao

2011-10-01

Since 2008, 28 patients with congenital mitral regurgitation have undergone mitral valve repair with a modified edge-to-edge technique at our institution. The regurgitant mitral leaflet was sutured with a pledget-reinforced, horizontal mattress suture with No. 4-0 polypropylene on the ventricle side and a pledget-reinforced mattress suture with Gore-Tex sutures (W.L. Gore & Associates, Flagstaff, AZ) and Dacron pledgets (Chest, Shanghai) placed on the anterior and posterior annulus corresponding to the edge-to-edge suturing site. Early results are encouraging, but a longer follow-up is needed. Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

SdrF, a Staphylococcus epidermidis Surface Protein, Contributes to the Initiation of Ventricular Assist Device Driveline–Related Infections

PubMed Central

Arrecubieta, Carlos; Toba, Faustino A.; von Bayern, Manuel; Akashi, Hirokazu; Deng, Mario C.; Naka, Yoshifumi; Lowy, Franklin D.

2009-01-01

Staphylococcus epidermidis remains the predominant pathogen in prosthetic-device infections. Ventricular assist devices, a recently developed form of therapy for end-stage congestive heart failure, have had considerable success. However, infections, most often caused by Staphylococcus epidermidis, have limited their long-term use. The transcutaneous driveline entry site acts as a potential portal of entry for bacteria, allowing development of either localized or systemic infections. A novel in vitro binding assay using explanted drivelines obtained from patients undergoing transplantation and a heterologous lactococcal system of surface protein expression were used to identify S. epidermidis surface components involved in the pathogenesis of driveline infections. Of the four components tested, SdrF, SdrG, PIA, and GehD, SdrF was identified as the primary ligand. SdrF adherence was mediated via its B domain attaching to host collagen deposited on the surface of the driveline. Antibodies directed against SdrF reduced adherence of S. epidermidis to the drivelines. SdrF was also found to adhere with high affinity to Dacron, the hydrophobic polymeric outer surface of drivelines. Solid phase binding assays showed that SdrF was also able to adhere to other hydrophobic artificial materials such as polystyrene. A murine model of infection was developed and used to test the role of SdrF during in vivo driveline infection. SdrF alone was able to mediate bacterial adherence to implanted drivelines. Anti-SdrF antibodies reduced S. epidermidis colonization of implanted drivelines. SdrF appears to play a key role in the initiation of ventricular assist device driveline infections caused by S. epidermidis. This pluripotential adherence capacity provides a potential pathway to infection with SdrF-positive commensal staphylococci first adhering to the external Dacron-coated driveline at the transcutaneous entry site, then spreading along the collagen-coated internal portion of the driveline to establish a localized infection. This capacity may also have relevance for other prosthetic device–related infections. PMID:19412528

[Results of a series of deltoid flaps for the treatment of massive rotator cuff tears with an average follow-up of 3.5 years].

PubMed

Le Huec, J C; Liquois, F; Schaeverbecke, T; Zipoli, B; Chauveaux, D; Le Rebeller, A

1996-01-01

We report a series of 14 patients with a massive rotator cuff tear operated on with a deltoid flap according to Augereau's technique. The aim of this study was to evaluate the benefits of this technique using Constant's scoring system. The follow up is 40 months. 14 patients, mean age 59 years, with a total rotator cuff tear type III according to Gerber's classification were included. There was 13 total ruptures of the supra and infra spinatus tendon and one infraspinatus and subscapularis lesion. All the patients had shoulder pain, and the preoperative, Constant's score was 24.1/100. The diagnosis of the rotator cuff rupture was confirmed by X-rays, arthrography and ultra-sonography. 8 patients had a Magnetic Resonance Imaging (MRI) evaluation. The surgical procedure was the technique described by Augereau, and three patients had a resection of the distal clavicle. One patient had a small piece of dacron to reinforce the suture of a very thin deltoid flap. All the patients had a immobilization in abduction and the rehabilitation programm began immediately. Results on pain were good: +11.4 points according to Constant's score, but improvement strength (+0.7 point) or motion (+1 point) was not significative. Postoperative Constant's score was 46.9, ponderated score increased from 29.5 per cent to 57.5 per cent. Ten patients were very satisfied, 2 were satisfied and two were disappointed. One of them neaded shoulder arthrodesis; the other needed a new surgery to remove the piece of dacron, and was allayed with NSAI drugs. External rotation was slightly increased: +2 point. These results are similar to others series on pain relief, but the results are poor on strength restauration and on shoulder motion. This technique is a heavy surgical procedure and results are not better than arthroscopic sub acromial decompression for massive rotator cuff tear.

Attitudes towards cytology and human papillomavirus self-sample collection for cervical screening among Hindu women in London, UK: a mixed methods study.

PubMed

Cadman, Louise; Ashdown-Barr, Lesley; Waller, Jo; Szarewski, Anne

2015-01-01

To explore the attitudes, views and understanding of women attending a Hindu temple in London, UK towards cervical screening, human papillomavirus (HPV) testing and two HPV self-sample collection devices: the Dacron swab and Evalyn(®) brush. A mixed methods design comprising a survey and four focus groups was adopted. Focus group discussions were recorded and transcribed verbatim and explored using thematic framework analysis. A total of 185 Hindu women completed surveys and 23 attended focus groups. Of the respondents 75% aged 25-64 years reported having cervical screening within the last 5 years; 85% had attended college or university. Familiar barriers to attendance for screening were identified: fear of pain and the test result, embarrassment, screener's attitude, inconvenient appointment times and difficulty with child care. Additional barriers cited included age and country of birth, with older and Indian-born women thought to be less likely to attend for screening. Self-collected sampling had a mixed reception. Women were not confident that their sample would be as good as a clinician sample and expressed concern about the impact that a positive HPV result might have on their relationships. Screening attendance in this highly educated group of Hindu women was slightly lower than in the general population (75% of women aged 25-64 years had been screened in the last 5 years compared with 79% in England as a whole). Familiar barriers to screening were identified. Women felt able to collect their own sample for HPV testing with a Dacron swab but lacked confidence that it would be as good as that obtained by a clinician. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Prosthetic vascular graft infection through a median sternotomy: a multicentre review †.

PubMed

Oda, Tatsuya; Minatoya, Kenji; Kobayashi, Junjiro; Okita, Yutaka; Akashi, Hidetoshi; Tanaka, Hiroyuki; Kawaharada, Nobuyoshi; Saiki, Yoshikatsu; Kuniyoshi, Yukio; Nishimura, Kunihiro

2015-06-01

The aim of this study is to analyse the treatment outcomes of thoracic prosthetic graft infection. A retrospective chart review was conducted at six hospitals and included the records of 68 patients treated for postoperative prosthetic vascular graft infection (mean age: 62.3 ± 15.1, male 51) from January 2000 to December 2013. The number of patients and the locations of the treated infections were as follows: 13 for aortic root, 16 for ascending aorta, 35 for aortic arch and 4 for aortic root to arch. In-hospital infection occurred in 43 patients and after discharge in 25. The mean follow-up time was 2.0 ± 2.3 years. The follow-up rate was 94.1%. The most commonly isolated micro-organism was Staphylococcus aureus (72.1%). Rereplacement of infectious graft was performed in 18 patients (Dacron graft in 12, homograft in 4 and rifampicin-bonded Dacron graft in 2). The overall hospital mortality rate was 35.3% (24/68). The mortality rate among the patients with graft rereplacement was 33.3% (6/18), with pedicled muscle flaps or pedicled omental flaps to cover the graft 25.9% (7/27), with irrigation 55.0% (11/20) and on antibiotic therapy only 0% (0/3). Our multivariate analysis demonstrated that the risk factors of hospital death increased in the absence of pedicled flaps (muscle or omentum) to cover the graft (P = 0.001), age over 55 (P = 0.003), time from onset of initial operation <1 week (P = 0.031) and period before 2008 (P = 0.001). The overall 1-year survival rate was 58.6%. The treatment outcomes of thoracic prosthetic vascular graft infection have not been satisfactory. However, the use of pedicled muscle or omental flaps to cover the graft could improve the outcomes. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Investigation of Kevlar fabric based materials for use with inflatable structures

NASA Technical Reports Server (NTRS)

Niccum, R. J.; Munson, J. B.

1974-01-01

Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported in detail. The practicality of using Kevlar in aerostat materials is demonstrated and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar based materials are compared with conventional, Dacron reinforced counterparts. A comprehensive test and qualification program is discussed and quantitative biaxial tensile and shear test data are provided. The investigation shows that single ply laminates of Kevlar and plastic films offer significant strength to weight improvements, are less permeable than two ply coated materials, but have a lower flex life.

Embolomycotic Aneurysm of External Iliac Artery

PubMed Central

Terán, Nemesio A.; Gonzalez, Nerio M.; García, Luis; Gonzalez, Freddy E.; Rivera, Humberto E.

1989-01-01

We report a case of embolomycotic aneurysm of the right iliac artery secondary to bacterial endocarditis. The patient, a 33-year-old woman, presented with unilateral hydronephrosis and lower extremity edema caused by aneurysmal compression of the ipsilateral ureter and the external iliac vein. She was treated with ligation and an extraperitoneal left-external-iliac-artery to right-femoral-artery bypass using a knitted Dacron prosthesis. Since her surgery, our patient has been well except for persistence of moderate leg edema. To the best of our knowledge, we are reporting the 1st case of embolomycotic external-iliac-artery aneurysm secondary to bacterial endocarditis and resulting in hydronephrosis and venous insufficiency. (Texas Heart Institute Journal 1989;16:51-55) Images PMID:15227238

Multi-Physics MRI-Based Two-Layer Fluid-Structure Interaction Anisotropic Models of Human Right and Left Ventricles with Different Patch Materials: Cardiac Function Assessment and Mechanical Stress Analysis

PubMed Central

Tang, Dalin; Yang, Chun; Geva, Tal; Gaudette, Glenn; del Nido, Pedro J.

2011-01-01

Multi-physics right and left ventricle (RV/LV) fluid-structure interaction (FSI) models were introduced to perform mechanical stress analysis and evaluate the effect of patch materials on RV function. The FSI models included three different patch materials (Dacron scaffold, treated pericardium, and contracting myocardium), two-layer construction, fiber orientation, and active anisotropic material properties. The models were constructed based on cardiac magnetic resonance (CMR) images acquired from a patient with severe RV dilatation and solved by ADINA. Our results indicate that the patch model with contracting myocardium leads to decreased stress level in the patch area, improved RV function and patch area contractility. PMID:21765559

Repair of Multiple Subclavian and Axillary Artery Aneurysms in a 58-Year-Old Man with Marfan Syndrome.

PubMed

Dolapoglu, Ahmet; de la Cruz, Kim I; Preventza, Ourania; Coselli, Joseph S

2016-10-01

Dilation of the ascending aorta and aortic dissections are often seen in Marfan syndrome; however, true aneurysms of the subclavian and axillary arteries rarely seem to develop in patients who have this disease. We present the case of a 58-year-old man with Marfan syndrome who had undergone a Bentall procedure and thoracoabdominal aortic repair for an aortic dissection and who later developed multiple aneurysmal dilations of his right subclavian and axillary arteries. The aneurysms were successfully repaired by means of a surgical bypass technique in which a Dacron graft was placed between the carotid and brachial arteries. We also discuss our strategy for determining the optimal surgical approach in these patients.

The Kiricuta procedure in reconstructive surgical treatment of the breast

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

Lopez, J.F.; Bouchet, Y.; Dupre, A.

1990-03-01

A series of 50 patients with carcinoma of the breast underwent omental transposition. This palliative procedure is indicated for recurrences after conservative treatment, radiation necrosis and Stage III or IV ulcerated tumors. The operative technique is described in detail. Omentoplasties were performed upon 33 right and 17 left mammary areas. Forty-five right pedicled flaps and only four left areas were used. One patient died on the fourth postoperative day because of massive pulmonary embolus. Local repair was satisfactory in 76 per cent of the patients. Four patients presented with herniation of the abdominal wall at the site of omental tunneling.more » In three, the treatment consisted of sectioning the vascular pedicle and reinforcing the parietal closure with Dacron (polyester fiber) mesh.« less

Ascending Aortic Stenting for Acute Supraaortic Stenosis From Graft Collapse.

PubMed

Lader, Joshua M; Smith, Deane E; Staniloae, Cezar; Fallahi, Arzhang; Iqbal, Sohah N; Galloway, Aubrey C; Williams, Mathew R

2018-06-01

A 78-year-old man with remote type-A dissection presented with acute-onset dyspnea. Twenty-two years prior, treatment for his aortic disease required replacement of ascending and arch aneurysms with a polyester graft (Dacron) using the graft inclusion technique. He presented currently in cardiogenic shock. Echocardiography demonstrated new severe hypokinesis of all apical segments. Left-heart catheterization revealed a 120 mm Hg intragraft gradient. Computed tomography arteriography was unrevealing, but intraaortic ultrasound demonstrated critical intragraft stenosis. A balloon expandable stent (Palmaz stent, Cordis, Milpitas, CA) was deployed in the stenotic region with gradient resolution. The patient later underwent aortic root replacement and ascending aneurysm repair (Bio-Bentall technique) and is doing well at 24 months. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Successful repair of a ventricular assist system percutaneous lead.

PubMed

Pantalos, G M; Marks, J D; Richardson, E E; Nelson, K E; Long, J W

1999-01-01

A patient with an implanted, electrically powered, ventricular assist device (Thermo Cardiosystems VE HeartMate) experienced a partial break of the percutaneous lead 5 months after implantation. The break (limited to the Silicone rubber tube) occurred at the junction of the lead with the Y-connector to the controller and vent, leaving approximately 5 cm of exposed lead from the skin exit site to the connector. Electronic and pumping functions of the pump continued, but the opening in the lead (which went more that half way around the circumference) prevented the use of pneumatic actuation as a back-up mode for pump operation, and placed the pump at risk for contamination. Repair of the lead without surgical intervention was desirable, with ease of repair and minimal risk to the patient being the top priorities. The use of multiple layers of heat-shrink tubing or external metal stents was ruled out in favor of a three stage repair procedure. The first stage involved the removal of the Dacron velour in-growth material from the lead to expose the underlying Silicone rubber tube. While the opening in the tube was held shut, a coating of medical grade Silicone rubber adhesive was applied to the tube, then wrapped with a woven Dacron mesh, followed by two layers of plastic wrapping material to protect the adhesive. This initial layer was secured by an external stent of tubing with cable ties. After several days to allow for complete curing of the adhesive, the adhesive coating with mesh was repeated. The final step involved a double layer wrap of a 1 mm thick Silicone rubber sheeting with mesh incorporation and adhesive secured in place with cable ties. After completion of the repair and verification of the ability to operate the device with pneumatic actuation, the patient was discharged with no recurrence of the problem after 8 months of weekly follow-up. This experience demonstrates the need to clinically anticipate component repair or replacement without total device replacement in future implantable blood pump systems.

Coronary flow characteristics after a Bentall procedure with or without sinuses of Valsalva.

PubMed

de Paulis, Ruggero; Tomai, Fabrizio; Bertoldo, Fabio; Ghini, Anna S; Scaffa, Raffaele; Nardi, Paolo; Chiariello, Luigi

2004-07-01

The sinuses of Valsalva are known to contribute to the normal function of the aortic valve. Little is known about their role in promoting coronary artery blood flow. The aim of this study was to compare coronary artery flow characteristics among patients undergoing a Bentall operation by means of a conventional cylindrical Dacron conduit or with a new conduit with pseudosinuses of Valsalva or in patients retaining their natural sinuses of Valsalva after aortic valve and supracoronary ascending aorta replacement. One year after a Bentall procedure with a standard cylindrical Dacron conduit (7 patients, group A) or with the new conduit (7 patients, group B), or after aortic valve and ascending aortic replacement (control group, 7 patients, group C) coronary flow velocity reserve and diastolic to systolic time integral ratio at baseline and after maximal hyperemia (with 40 microg of adenosine) were assessed by using a 0.014-in. Doppler guidewire positioned in the middle portion of the left anterior descending coronary artery. All patients were in NYHA class I, sinus rhythm and free of coronary disease. Arterial blood pressures and heart rate were comparable among groups. Intracoronary Doppler measurements did not show any significant difference in coronary vascular reserve between the three groups (3.6+/-0.4 vs 3.1+/-0.7 vs 3.7+/-0.5, P = 0.2). A greater diastolic component at baseline was present in group B patients (5.5+/-1.9 vs 3.5+/-0.9 in group A and 3.7+/-0.9 in group C, P = 0.024). After maximal hyperemia the diastolic component increased slightly in group A patients (8%) while both in groups B and C significantly decreased (-15 and -20%, respectively) (P = 0.017). The presence of pseudosinuses of Valsalva does not influence coronary flow reserve. After maximal coronary vasodilation the increase in the systolic component of coronary flow is more evident in the presence of sinuses or pseudosinuses of Valsalva, thus suggesting that coronary flow pattern may be affected by the presence of sinuses.

[Postoperative evaluation of surgically treated cases with temporary silicone implant in temporomandibular joint].

PubMed

Aoyama, Shigeru; Kino, Koji; Shibuya, Toshihisa; Sato, Fumiaki; Kobayashi, Akiko; Yoshitake, Hiroyuki; Haketa, Tadasu; Amamori, Yoko; Ishikawa, Takayuki; Yoshida, Nahoko; Amagasa, Teruo

2003-09-01

We have carried out temporary silicone implants after diskectomies or arthroplasties in temporomandibular joint surgeries to avoid postoperative adhesion and to maintain articular space. We evaluated 19 joints in 15 patients who had received dacron-reinforced silicone implant after silicone sheet removal through follow-up for at least 6 months. The cases included temporomandibular joint disorder (10 joints in 9 patients), psoriatic arthritis (2 joints in 1 patient), ankylosis (4 joints in 3 patients) and synovial chondromatosis (2 joints in 2 patients). On the basis of the criteria of temporomandibular dysfunction for the results, they were classified as bad (4 patients). It is thought that factors other than the implant are related to the bad results in the postoperative evaluation. In this study, lymphadenopathy induced by exfoliated silicone debris could not be confirmed. The temporary silicone implant in the temporomandibular joint was thought to be useful.

Live intramacrophagic Staphylococcus aureus as a potential cause of antibiotic therapy failure: observations in an in vivo mouse model of prosthetic vascular material infections.

PubMed

Boudjemaa, Rym; Steenkeste, Karine; Jacqueline, Cédric; Briandet, Romain; Caillon, Jocelyne; Boutoille, David; Le Mabecque, Virginie; Tattevin, Pierre; Fontaine-Aupart, Marie-Pierre; Revest, Matthieu

2018-06-12

To evaluate the significant role played by biofilms during prosthetic vascular material infections (PVMIs). We developed an in vivo mouse model of Staphylococcus aureus PVMI allowing its direct observation by confocal microscopy to describe: (i) the structure of biofilms developed on Dacron® vascular material; (ii) the localization and effect of antibiotics on these biostructures; and (iii) the interaction between bacteria and host tissues and cells during PVMI. In this model we demonstrated that the biofilm structures are correlated to the activity of antibiotics. Furthermore, live S. aureus bacteria were visualized inside the macrophages present at the biofilm sites, which is significant as antibiotics do not penetrate these immune cells. This intracellular situation may explain the limited effect of antibiotics and also why PVMIs can relapse after antibiotic therapy.

Atresia of the Descending Aorta in a Young Woman Requiring Bypass Graft.

PubMed

Dsc, Adcasdc Sadfasdf; Mashhood, Ammarah; Ali, Taimur Asif; Fatimi, Saulat Hasnain

2016-11-01

Congenital aortic atresia is a malformation accounting for 4 - 6% of all congenital heart diseases in children. Left ventricular outflow obstruction due to atresia is common at the aortic valve but rarely has atresia been identified in the descending aorta. We report the case of a 25-year woman who was evaluated for headache and uncontrolled hypertension. CTscan chest showed a short atretic segment in the descending aorta at the isthmus, distal to the takeoff of the subclavian artery. She underwent surgery; a 22 mm Dacron graft was taken and jump graft was placed between the arch of the aorta and the descending aorta, using partial occlusion clamps. Patient tolerated the procedure well and was discharged on ACE Inhibitors and beta blockers, which were then weaned off over a period of one year. She remained stable and had no further complaints.

Surgical treatment of left ventricular outflow tract obstruction with apicoaortic valved conduit.

PubMed

Cooley, D A; Norman, J C; Reul, G J; Kidd, J N; Nihill, M R

1976-12-01

From Aug. 13, 1975, through May, 1976, nine patients underwent creation of a left ventricular "vent" for relief of severe left ventricular outflow tract obstruction. A Dacron fabric graft containing a heterograft valve was used to establish a conduit from the left ventricle to the abdominal aorta. There were five male and four female patients in this group; their ages ranged from 4 to 72 years. All had valvular, subvalvular, or supravalvular aortic stenosis, and all but two had undergone previous surgical procedures for relief of the stenosis. All patients survived the operation and none are receiving anticoagulant therapy. All are asymptomatic at present and follow-up is approaching one year. Postoperative cardiac catheterization studies revealed gradients across the aortic valve to be reduced by approximately 90% and mean ventricular systolic pressures by 45%. Although this concept is not new, it has not been used widely and we believe its effectiveness warrants further application.

Utilizing the Foreign Body Response to Grow Tissue Engineered Blood Vessels in Vivo.

PubMed

Geelhoed, Wouter J; Moroni, Lorenzo; Rotmans, Joris I

2017-04-01

It is well known that the number of patients requiring a vascular grafts for use as vessel replacement in cardiovascular diseases, or as vascular access site for hemodialysis is ever increasing. The development of tissue engineered blood vessels (TEBV's) is a promising method to meet this increasing demand vascular grafts, without having to rely on poorly performing synthetic options such as polytetrafluoroethylene (PTFE) or Dacron. The generation of in vivo TEBV's involves utilizing the host reaction to an implanted biomaterial for the generation of completely autologous tissues. Essentially this approach to the development of TEBV's makes use of the foreign body response to biomaterials for the construction of the entire vascular replacement tissue within the patient's own body. In this review we will discuss the method of developing in vivo TEBV's, and debate the approaches of several research groups that have implemented this method.

Influence of thermofixation on artificial ACL ligament dimensional and mechanical properties

NASA Astrophysics Data System (ADS)

Ben Abdessalem, S.; Jedda, H.; Skhiri, S.; Karray, S.; Dahmen, J.; Boughamoura, H.

2005-11-01

The anterior cruciate ligament (ACL) is the major articular ligamentous structure of the knee, it functions as a joint stabilizer. When ruptured, the natural ACL ligament can be replaced by a textile synthetic ligament such as a braid, knitted cord, or woven cord. Theses structures are composed of biocompatible materials such as polyester or Gore-Tex filaments. The success of an ACL replacement is widely linked to its mechanical and dimensional properties such as tensile strength, dimensional stability and resistance to abrasion. We introduced an additional treatment in the manufacturing of textile ACL ligaments based on the thermofixation of the textile structure by using textile industry stabilization techniques. Boiling water, saturated vapor and dry heat have been tested to stabilize a braided ligament made of Dacron polyester. The application of these three techniques led to shrinkage and an increase of breaking strength of the textile structure.

Synthetic devices for reconstructive surgery of the cruciate ligaments: a systematic review.

PubMed

Batty, Lachlan M; Norsworthy, Cameron J; Lash, Nicholas J; Wasiak, Jason; Richmond, Anneka K; Feller, Julian A

2015-05-01

The role of synthetic devices in the management of the cruciate ligament-injured knee remains controversial. The aim of this systematic review was to assess the safety and efficacy of synthetic devices in cruciate ligament surgery. A systematic review of the electronic databases Medline, Embase, and The Cochrane Library (issue 1, 2014) on January 13, 2014, was performed to identify controlled and uncontrolled trials. Trials that assessed the safety and efficacy of synthetic devices for cruciate ligament surgery were included. The main variables assessed included rates of failure, revision, and noninfective effusion and synovitis. Patient-reported outcome assessments and complications were also assessed where reported. From 511 records screened, we included 85 articles published between 1985 and 2013 reporting on 6 synthetic devices (ligament augmentation and reconstruction system [Ligament Augmentation and Reconstruction System (LARS; Surgical Implants and Devices, Arc-sur-Tille, France)]; Leeds-Keio [Xiros (formerly Neoligaments), Leeds, England]; Kennedy ligament augmentation device [3M, St Paul, MN]; Dacron [Stryker, Kalamazoo, MI]; Gore-Tex [W.L. Gore and Associates, Flagstaff, AZ]; and Trevira [Telos (limited liability company), Marburg, Germany]). The heterogeneity of the included studies precluded meta-analysis. The results were analyzed by device and then type of reconstruction (anterior cruciate ligament [ACL]/posterior cruciate ligament [PCL]/combined ACL and PCL). The lowest cumulative rates of failure were seen with the LARS device (2.6% for ACL and 1% for PCL surgery). The highest failure rate was seen in the Dacron ACL group (cumulative rate, 33.6%). Rates of noninfective synovitis and effusion ranged from 0.2% in the LARS ACL group to 27.6% in the Gore-Tex ACL group. Revision rates ranged from 2.6% (LARS) to 11.8% (Trevira-Hochfest; Telos). Recent designs, specifically the LARS, showed good improvement in the outcome scores. The mean preoperative and postoperative Lysholm knee scores were 54 and 88, respectively; the mean preoperative and postoperative Tegner activity scale scores were 3.3 and 6, respectively. Preliminary results for newer-generation devices, specifically the LARS, show lower reported rates of failure, revision, and sterile effusion/synovitis when compared with older devices. Level IV, systematic review of Level II through IV studies. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Detection of Bordetella pertussis in Infants Suspected to have Whooping Cough.

PubMed

Hajia, Massoud; Rahbar, Mohammad; Fallah, Fatemeh; Safadel, Nooshafarin

2012-01-01

Even with high coverage of vaccination programs, Bordetella pertussis is still reported in various countries. It causes a high rate of mortality and morbidity in infants while it could be asymptomatic in adults. At the present study, we are going to evaluate the frequency of B. pertussis among received specimens. This cross-sectional study was performed on 138 children under one year who were suspected to have whooping cough from October 2008 to March in 2011. Nasopharyngeal dacron and rayon swabs and sera were used for PCR and serology respectively. The mean age of the subjects was 1.9± 0.9 months. PCR was positive in 12 cases; ELISA was in agreement with PCR results except in one case that showed the specific antibody at borderline limit. The rate of reported positive results showed that pertussis not only is still present in the community, but the number of the asymptomatic cases who are able to transmit the disease may be considerable.

Unusual Presentation of Melioidosis in a Case of Pseudoaneurysm of Descending Thoracic Aorta: Review of Two Case Reports

PubMed Central

Padmaja, Kanne; Lakshmi, Vemu; Sudhaharan, Sukanya; Venkata Surya Malladi, Subbalaxmi; Gopal, Palanki; Venkata Ravinuthala, Kumar

2015-01-01

Introduction: Melioidosis is a rapidly fatal infectious disease caused by Burkholderia pseudomallei, an agent of potential biothreat, endemic in several parts of India. Most melioidosis-induced infected aneurysms are located in the abdominal or thoracic aorta. Case Presentation: We reported two unusual cases of melioidosis resulting in pseudoaneurysm of the descending thoracic aorta. In both cases, blood cultures yielded B. pseudomallei. The first patient was managed with resection of aneurysm and reconstruction with Dacron graft followed by medical treatment and was discharged uneventfully. The second patient died within one week of admission before the infecting etiological agent was identified and aneurysmal repair was planned. Conclusions: A high clinical index of suspicion, especially in areas of endemicity is essential for timely management of intracavitary infected pseudoaneurysms caused by B. pseudomallei and use of rapid microbiological techniques, such as bact/alert 3D system, which enables rapid and early recovery of the etiological agent. PMID:26380820

ECN-2301

NASA Image and Video Library

1969-09-10

The Hyper III was a low-cost test vehicle for an advanced lifting-body shape. Like the earlier M2-F1, it was a "homebuilt" research aircraft, i.e., built at the Flight Research Center (FRC), later redesignated the Dryden Flight Research Center. It had a steel-tube frame covered with Dacron, a fiberglass nose, sheet aluminum fins, and a wing from an HP-11 sailplane. Construction was by volunteers at the FRC. Although the Hyper III was to be flown remotely in its initial tests, it was fitted with a cockpit for a pilot. On the Hyper III's only flight, it was towed aloft attached to a Navy SH-3 helicopter by a 400-foot cable. NASA research pilot Bruce Peterson flew the SH-3. After he released the Hyper III from the cable, NASA research pilot Milt Thompson flew the vehicle by radio control until the final approach when Dick Fischer took over control using a model-airplane radio-control box. The Hyper III flared, then landed and slid to a stop on Rogers Dry Lakebed.

Nonlinear dynamics of shells conveying pulsatile flow with pulse-wave propagation. Theory and numerical results for a single harmonic pulsation

NASA Astrophysics Data System (ADS)

Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.

2017-05-01

In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and deformation of the shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron aortic prosthesis is modelled as an orthotropic circular cylindrical shell described by means of the Novozhilov nonlinear shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. For the first time in literature, coupled fluid-structure Lagrange equations of motion for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron aortic graft conveying blood flow. A pulsatile time-dependent blood flow model is considered by applying the first harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure, considering the propagation of pressure and velocity changes inside the shell, is here presented via frequency-response curves, time histories, bifurcation diagrams and Poincaré maps. It is shown that traveling waves of pressure and velocity cause a delay in the radial displacement of the shell at different values of the axial coordinate. The effect of different pulse wave velocities is also studied. Comparisons with the corresponding ideal case without wave propagation (i.e. with the same pulsatile velocity and pressure at any point of the shell) are here discussed. Bifurcation diagrams of Poincaré maps obtained from direct time integration have been used to study the system in the spectral neighborhood of the fundamental natural frequency. By increasing the forcing frequency, the response undergoes very complex nonlinear dynamics (chaos, amplitude modulation and period-doubling bifurcation), here deeply investigated.

Early Results of the PETTICOAT Technique for the Management of Acute Type A Aortic Dissection.

PubMed

Kotha, Vamshi Krishna; Pozeg, Zlatko I; Herget, Eric J; Moon, Michael C; Appoo, Jehangir J

2017-08-01

Conventional surgical techniques for acute Type A aortic dissection (ATAAD) generally fail to address residual dissection in the descending aorta. The persistence of a false lumen is associated with visceral malperfusion in the acute setting and adverse aortic remodeling in the chronic setting. Hybrid aortic arch repair techniques may improve perioperative and long-term mortality by expanding the true lumen and obliterating the false lumen. However, there is a limit to the extent of aortic coverage due to the concomitant risk of spinal cord ischemia. In Type B dissection, the PETTICOAT (Provisional Extension To Induce Complete Attachment) technique, which entails stent graft coverage of the primary intimal tear followed by bare metal stent placement distally, may improve true lumen caliber and promote false lumen thrombosis without increasing the risk of spinal cord ischemia, as intercostal branches remain perfused through the bare metal stents. The technique of hybrid arch with surgical creation of a Dacron landing zone covering a stent graft in the proximal descending aorta and bare metal stents in the thoraco-abdominal aorta is a promising concept in the treatment of ATAAD.

The surgical treatment of ilio-femoral venous obstruction.

PubMed

Illuminati, G; Caliò, F G; D'Urso, A; Mancini, P; Papaspyropoulos, V; Ceccanei, G; Lorusso, R; Vietri, F

2004-01-01

A series of 9 patients of a mean age of 48 years, operated on for compression of the ilio-femoral venous axis is reported. The cause of obstruction was external compression in 3 cases, a retroperitoneal sarcoma in 1 case, and an infrarenal aortic aneurysm in 2. Two patients presented with a Cockett's syndrome, 3 with a chronic ilio-femoral thrombosis, and one with a post-traumatic segmentary stenosis. Treatment consisted in a resection/Dacron grafting of 2 infrarenal aortic aneurysms, one femoro-caval bypass graft, 2 transpositions of the right common iliac artery in the left hypogastric artery for Cockett's syndrome, 3 Palma's operations for chronic thrombosis, and one internal jugular vein interposition for segmentary stenosis. There were no postoperative deaths and no early thromboses of venous reconstructions performed. All the patients were relieved of symptoms during the follow-up period, whose mean length was 38 months. The cause of venous obstruction and the presence of symptoms which are resistant to medical treatment are the main indications to ilio-femoral venous revascularization. The choice of the optimal treatment in each single case yields satisfactory results.

[Decompensated valvular disease and coarctation. One-stage repair using a median approach with an ascending aorta-abdominal aorta shunt].

PubMed

Baille, Y; Sigwalt, M; Vaillant, A; Sicard Desnuelle, M P; Varnet, B

1981-11-01

The tactical decision in patients with decompensated valvular disease associated with a severe stenosis of the aortic isthmus is always difficult. One stage surgical repair using two separate approaches is a long and high risk procedure. It would seem more logical and safer to treat the lesions in two stages a few weeks apart, the severest lesion being managed first. In the two cases reported. The isthmic stenoses and valvular lesions were of the same severity and made both classical techniques impracticable. Therefore the patients underwent a single stage procedure by a median approach associating valve replacement under cardiopulmonary bypass (mitral and tricuspid in one and aortic in the other case) and an ascending aorta-abdominal aorta dacron conduit. The present postoperative survival periods are 30 and 9 months. The functional result was good (Class 1 and 0) and postoperative angiography has shown the montage to be working satisfactorily. This technique is exceptional but may be useful in borderline cases with decompensated valvular disease and severe isthmic stenosis.

CFM technologies for space transportation: Multipurpose hydrogen testbed system definition and tank procurement

NASA Technical Reports Server (NTRS)

Fox, E. C.; Kiefel, E. R.; Mcintosh, G. L.; Sharpe, J. B.; Sheahan, D. R.; Wakefield, M. E.

1993-01-01

The development of a test bed tank and system for evaluating cryogenic fluid management technologies in a simulated upper stage liquid hydrogen tank is covered. The tank is 10 ft long and is 10 ft in diameter, and is an ASME certified tank constructed of 5083 aluminum. The tank is insulated with a combination of sprayed on foam insulation, covered by 45 layers of double aluminized mylar separated by dacron net. The mylar is applied by a continuous wrap system adapted from commercial applications, and incorporates variable spacing between the mylar to provide more space between those layers having a high delta temperature, which minimizes heat leak. It also incorporates a unique venting system which uses fewer large holes in the mylar rather than the multitude of small holes used conventionally. This significantly reduces radiation heat transfer. The test bed consists of an existing vacuum chamber at MSFC, the test bed tank and its thermal control system, and a thermal shroud (which may be heated) surrounding the tank. Provisions are made in the tank and chamber for inclusion of a variety of cryogenic fluid management experiments.

Experimental testing of a foam/multilayer insulation (FMLI) thermal control system (TCS) for use on a cryogenic upper stage

NASA Astrophysics Data System (ADS)

Hastings, Leon J.; Martin, James J.

1998-01-01

An 18-m3 system-level test bed termed the Multipurpose Hydrogen Test Bed (MHTB has been used to evaluate a foam/multilayer combination insulation concept. The foam element (Isofoam SS-1171) protects against ground hold/ascent flight environments, and allows the use of dry nitrogen purge as opposed to a more complex/heavy helium purge subsystem. The MLI (45 layers of Double Aluminized Mylar with Dacron spacers) is designed for an on-orbit storage period of 45 days. Unique MLI features included; a variable layer density (reduces weight and radiation losses), larger but fewer DAM vent perforations (reduces radiation losses), and a roll wrap installation which resulted in a very robust MLI and reduced both assembly man-hours and seam heat leak. Ground hold testing resulted in an average heat leak of 63 W/m2 and purge gas liquefaction was successfully prevented. The orbit hold simulation produced a heat leak of 0.22 W/m2 with 305 K boundary which, compared to historical data, represents a 50-percent heat leak reduction.

Early Results of the PETTICOAT Technique for the Management of Acute Type A Aortic Dissection

PubMed Central

Kotha, Vamshi Krishna; Pozeg, Zlatko I.; Herget, Eric J.; Moon, Michael C.; Appoo, Jehangir J.

2017-01-01

Conventional surgical techniques for acute Type A aortic dissection (ATAAD) generally fail to address residual dissection in the descending aorta. The persistence of a false lumen is associated with visceral malperfusion in the acute setting and adverse aortic remodeling in the chronic setting. Hybrid aortic arch repair techniques may improve perioperative and long-term mortality by expanding the true lumen and obliterating the false lumen. However, there is a limit to the extent of aortic coverage due to the concomitant risk of spinal cord ischemia. In Type B dissection, the PETTICOAT (Provisional Extension To Induce Complete Attachment) technique, which entails stent graft coverage of the primary intimal tear followed by bare metal stent placement distally, may improve true lumen caliber and promote false lumen thrombosis without increasing the risk of spinal cord ischemia, as intercostal branches remain perfused through the bare metal stents. The technique of hybrid arch with surgical creation of a Dacron landing zone covering a stent graft in the proximal descending aorta and bare metal stents in the thoraco-abdominal aorta is a promising concept in the treatment of ATAAD. PMID:29657948

Evolution of the mandibular mesh implant.

PubMed

Salyer, K E; Johns, D F; Holmes, R E; Layton, J G

1977-07-01

Between 1960 and 1972, the Dallas Veterans Administration Hospital Maxillofacial Research Laboratory developed and made over 150 cast-mesh implants. Successive designs were ovoid, circular, and double-lumened in cross section to improve implant strength, surface area for bioattachment, and adjustability. Sleeves, collars, and bows were employed in the assembly of these implants, with an acrylic condylar head attached when indicated. In 1972, our laboratory developed a mandibular mesh tray, cast in one piece on a single sprue, with preservation of the vertically adjustable ramus. Stainless steel replaced Vitallium because of its greater malleability. Essentially, a lost-wax technique is used to cast the mesh tray. The model of a mandibular segment is duplicated as a refractory model. Mesh wax, made in our own custom-made die, is adapted to the refractory model. The unit is then sprued and invested. The wax is fired our of the mold in a gas furnace. Casting is done by the transferral of molten stainless steel from the crucible to the mold by centrifugal force in an electro-induction casting machine. Other mesh implants that have been developed are made from wire mesh, Dacron mesh, cast Ticonium, and hydroformed titanium.

Effects of radio transmitters on migrating wood thrushes

USGS Publications Warehouse

Powell, L.A.; Krementz, D.G.; Lang, J.D.; Conroy, M.J.

1998-01-01

We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of Wood Thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores. We used two strengths of line, 5- and 9-kg test-strength braided Dacron, to attach the transmitters using the thigh-harness method. We recaptured 13 returning radio-marked Wood Thrushes, seven of which were still marked. Six of the seven birds marked with the 5-kg test harnesses lost their transmitters within 1 yr while all six of the 9-kg test harnesses were still attached up to 21 mo later. Radio-marking did not reduce the return rates of adults and immatures, and the transmitters did not cause radio-marked birds to lose more mass than banded-only birds. Wood Thrushes can successfully carry a transmitter during migration with no detectable negative effects. We recommend continued use of the thigh-harness method, but we encourage the use of 5-kg cotton line.

Mechanical circulatory support of a univentricular Fontan circulation with a continuous axial-flow pump in a piglet model.

PubMed

Wei, Xufeng; Sanchez, Pablo G; Liu, Yang; Li, Tieluo; Watkins, A Claire; Wu, Zhongjun J; Griffith, Bartley P

2015-01-01

Despite the significant contribution of the Fontan procedure to the therapy of complex congenital heart diseases, many patients progress to failure of their Fontan circulation. The use of ventricular assist devices to provide circulatory support to these patients remains challenging. In the current study, a continuous axial-flow pump was used to support a univentricular Fontan circulation. A modified Fontan circulation (atrio-pulmonary connection) was constructed in six Yorkshire piglets (8-14 kg). A Dacron conduit (12 mm) with two branches was constructed to serve as a complete atrio-pulmonary connection without the use of cardiopulmonary bypass. The Impella pump was inserted into the conduit through an additional Polytetrafluoroethylene (PTFE) graft in five animals. Hemodynamic data were collected for 6 hours under the supported Fontan circulation. The control animal died after initiating the Fontan circulation independent of resuscitation. Four pump supported animals remained hemodynamically stable for 6 hours with pump speeds between 18,000 rpm and 22,000 rpm (P1-P3). Oxygen saturation was maintained between 95% and 100%. Normal organ perfusion was illustrated by blood gas analysis and biochemical assays. A continuous axial-flow pump can be used for temporal circulatory support to the failing Fontan circulation as "bridge" to heart transplantation or recovery.

Spacecraft thermal blanket cleaning: Vacuum bake of gaseous flow purging

NASA Technical Reports Server (NTRS)

Scialdone, John J.

1990-01-01

The mass losses and the outgassing rates per unit area of three thermal blankets consisting of various combinations of Mylar and Kapton, with interposed Dacron nets, were measured with a microbalance using two methods. The blankets at 25 deg C were either outgassed in vacuum for 20 hours, or were purged with a dry nitrogen flow of 3 cu. ft. per hour at 25 deg C for 20 hours. The two methods were compared for their effectiveness in cleaning the blankets for their use in space applications. The measurements were carried out using blanket strips and rolled-up blanket samples fitting the microbalance cylindrical plenum. Also, temperature scanning tests were carried out to indicate the optimum temperature for purging and vacuum cleaning. The data indicate that the purging for 20 hours with the above N2 flow can accomplish the same level of cleaning provided by the vacuum with the blankets at 25 deg C for 20 hours, In both cases, the rate of outgassing after 20 hours is reduced by 3 orders of magnitude, and the weight losses are in the range of 10E-4 gr/sq cm. Equivalent mass loss time constants, regained mass in air as a function of time, and other parameters were obtained for those blankets.

Spacecraft thermal blanket cleaning - Vacuum baking or gaseous flow purging

NASA Technical Reports Server (NTRS)

Scialdone, John J.

1992-01-01

The mass losses and the outgassing rates per unit area of three thermal blankets consisting of various combinations of Mylar and Kapton, with interposed Dacron nets, were measured with a microbalance using two methods. The blankets at 25 deg C were either outgassed in vacuum for 20 hours, or were purged with a dry nitrogen flow of 3 cu. ft. per hour at 25 deg C for 20 hours. The two methods were compared for their effectiveness in cleaning the blankets for their use in space applications. The measurements were carried out using blanket strips and rolled-up blanket samples fitting the microbalance cylindrical plenum. Also, temperature scanning tests were carried out to indicate the optimum temperature for purging and vacuum cleaning. The data indicate that the purging for 20 hours with the above N2 flow can accomplish the same level of cleaning provided by the vacuum with the blankets at 25 deg C for 20 hours. In both cases, the rate of outgassing after 20 hours is reduced by 3 orders of magnitude, and the weight losses are in the range of 10E-4 gr/sq cm. Equivalent mass loss time constants, regained mass in air as a function of time, and other parameters were obtained for those blankets.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

NASA Astrophysics Data System (ADS)

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on an 87.6 in. diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr, respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

A novel low-profile thin-film nitinol/silk endograft for treating small vascular diseases.

PubMed

Shayan, Mahdis; Yang, Sungyeun; Ryu, WonHyoung; Chun, Youngjae

2017-04-01

Since the introduction of various endovascular graft materials such as expanded polytetrafluoroethylene (e-PTFE) and Dacron ® polyester, they have been rapidly applied in endovascular devices for treating a variety of clinical situations. While present endovascular grafts have been successful in treating large blood vessels, there are still significant challenges and limitations for small and tortuous vessels to their use. Recently, our group has demonstrated the potential to use thin-film nitinol (TFN) as a novel material to develop endografts used in the treatment of a wide range of small vascular diseases because TFN is ultralow profile (that is, a few micrometers thick), relatively thromboresistant, and superelastic. While TFN has shown superior thromboresistance, its surface endothelialization is not rapid and sufficient. Therefore, our laboratory has been exploring the feasibility of using thin-film silk as a novel coating for facilitating rapid and confluent endothelial cell growth. The purpose of this study is to fabricate a low-profile composite endograft using thin layers of nitinol and silk, and to evaluate both thrombogenicity as well as endothelial cell and smooth muscle cell responses. This study also evaluates the functionality of the composite endograft using an in vitro blood circulation model. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 575-584, 2017. © 2015 Wiley Periodicals, Inc.

Long-term results of the use of silicone sheets after diskectomy in the temporomandibular joint: clinical, radiographic and histopathologic findings.

PubMed

Schliephake, H; Schmelzeisen, R; Maschek, H; Haese, M

1999-10-01

The aim of the present study was to evaluate the long-term results of a group of patients who had the disk of the temporomandibular joint (TMJ) removed and permanently replaced by a silicone sheet. The study group comprised 48 patients, treated in the period from 1983 to 1993. In eight patients, the implants had to be removed after an average interval of 5.6 years and they were submitted for histopathological examination. Twenty-five of the 40 patients with silastic implants in place, and five of the 8 patients who had their implants removed, were available for long-term follow-up (mean interval of 7.0 years, SD 2.8 years). Clinical function was rated according to the Helkimo Dysfunction Index and compared to the preoperative findings. Results showed decreased tenderness of muscles and joints to palpation and increased mouth opening, but no statistically significant improvement in joint function. In 4 patients, a decrease in condylar width was found, while another 4 patients presented with thickening of the condyle by appositional bone formation. Histopathology of the failed implants showed scattered fragments of silastic material and dacron fibers with accumulation of histiocytes in immediate contact with the silicone particles and phagocytozed intracellular material. T-lymphocytes were also present in the vicinity of the silicone particles.

External aortic wrap for repair of type 1 endoleak☆

PubMed Central

Dean, Anastasia; Yap, Swee Leong; Bhamidipaty, Venu; Pond, Franklin

2014-01-01

INTRODUCTION Type 1 endoleak is a rare complication after endovascular abdominal aortic aneurysm repair (EVAR) with a reported frequency up to 2.88%. It is a major risk factor for aneurysmal enlargement and rupture. PRESENTATION OF CASE We present a case of a 68 year old gentleman who was found to have a proximal type 1 endoleak with loss of graft wall apposition on routine surveillance imaging post-EVAR. An initial attempt at endovascular repair was unsuccessful. Given the patient's multiple medical co-morbidities, which precluded the possibility of conventional graft explantation and open repair, we performed a novel surgical technique which did not require aortic cross-clamping. A double-layered Dacron wrap was secured around the infra-renal aorta with Prolene sutures, effectively hoisting the posterior bulge to allow wall to graft apposition and excluding the endoleak. Post-operative CT angiogram showed resolution of the endoleak and a stable sac size. DISCUSSION Several anatomical factors need to be considered when this technique is proposed including aortic neck angulation, position of lumbar arteries and peri-aortic venous anatomy. While an external wrap technique has been investigated sporadically for vascular aneurysms, to our knowledge there is only one similar case in the literature. CONCLUSION Provided certain anatomical features are present, an external aortic wrap is a useful and successful option to manage type 1 endoleak in high-risk patients who are unsuitable for aortic clamping. PMID:25217878

Coronary reconnection in emergency "conduit operation" for acute type-a aortic dissection with aortic insufficiency: experience with 24 cases.

PubMed

Massimo, C G; Presenti, L F; Favi, P P; Duranti, A; Poma, A G; Marranci, P; Modiano, C

1987-12-01

Twenty-four cases of acute type-A aortic dissection with aortic valvular insufficiency were treated in our institution by means of an emergency operation in which the aortic valve, ascending aorta, and aortic arch were resected and replaced with a valved conduit that had been lengthened with a tubular Dacron graft. The procedure included the use of deep hypothermia for cerebral protection, as well as extracorporeal circulation. Aortic resection was performed from the aortic valve to the origin of the descending thoracic aorta; the aortic graft was anastomosed proximally to the valve annulus and distally to the descending aorta. The carotid orifices were connected to the side of the graft in a single tissue button. The coronary arteries were then reconnected by means of double venous bypass grafts to the innominate artery, to allow for inclusion of the graft. Within 1 month after operation, four patients died of the consequences of dissection. Six months postoperatively, one patient succumbed to an infarction. Six months to 5 years after operation, the remaining 19 patients are still alive. On the basis of this experience, we believe that acute type-A aortic dissection with aortic valvular insufficiency should be treated during the first hours after the onset of symptoms. The above-described procedure proved effective in the control of bleeding, which is the major risk in emergency operations of this type.

Design of Maternity Pillow by Using Kansei and Taguchi Methods

NASA Astrophysics Data System (ADS)

Ilma Rahmillah, Fety; Nanda kartika, Rachmah

2017-06-01

One of the customers’ considerations for purchasing a product is it can satisfy their feeling and emotion. It because of such product can enhance sleep quality of pregnant women. However, most of the existing product such as maternity pillows are still designed based on companies’ perspective. This study aims to capture the desire of pregnant women toward maternity pillow desired product by using kansei words and analyze the optimal design with Taguchi method. Eight collected kansei words were durable, aesthetic, comfort, portable, simple, multifunction, attractive motive, and easy to maintain. While L16 orthogonal array is used because there are three variables with two levels and four variables with four levels. It can be concluded that the best maternity pillow that can satisfy the customers can be designed by combining D1-E2-F2-G2-C1-B2-A2 means the model is U shape, flowery motive, medium color, Bag model B, cotton pillow cover, filled with silicon, and use double zipper. However, it is also possible to create combination of D1-E2-F2-G2-C1-B1-A1 by using consideration of cost which means that the zipper is switched to single as well as filled with dacron. In addition, the total percentage of contribution by using ANOVA reaches 95%.

High-value utilization of eucalyptus kraft lignin: Preparation and characterization as efficient dye dispersant.

PubMed

Zhang, Hui; Yu, Boming; Zhou, Wanpeng; Liu, Xinxin; Chen, Fangeng

2018-04-01

The dark color of industrial lignin is the main obstacle for their high value-added use in areas such as dyestuff dispersants. A kind of light-colored lignosulfonate with favorable dispersibility and remarkable stain resistance is prepared using fractionated eucalyptus kraft lignin. The fractionated lignins named as D (insoluble part) and X (soluble part) and sulfonated lignin fractions named as SD and SX are characterized by FTIR spectroscopy, 1 H NMR spectroscopy, GPC and brightness test. The results reveal that fraction X presents a lower molecular weight but a higher hydroxyl content than that of fraction D, which lead to the differences on the SO 3 H content, dispersibility and color performance of SD and SX. The sulfonated fractions perform a similar molecular weight to that of unsulfonated lignins and show light color due to the phenolic hydroxyl blocking of 1,4-BS (1,4-butane sultone) and the postprocessing of sodium borohydride. The SX that performs the best of all exhibits obvious decrease on phenolic hydroxyl groups and increase on brightness value which is improved by 85.8% compared with control sample. The SX reaches the highest level (grade 5) in the dispersibility test and presents remarkable stain resistance on different textiles, especially on the dacron and cotton. Copyright © 2017 Elsevier B.V. All rights reserved.

Aortoiliac aneurysm with congenital right pelvic kidney.

PubMed

Date, Kazuma; Okada, Shuuichi; Ezure, Masahiko; Takihara, Hitomi; Okonogi, Shuuichi; Hasegawa, Yutaka; Sato, Yasushi; Kaneko, Tatsuo

2015-05-01

The association of congenital pelvic kidney with abdominal aortoiliac aneurysm is an extremely rare clinical finding. Previous reports have described various methods of aneurysm repair with successful preservation of the function of pelvic kidney. However, to our knowledge, reconstruction of more than two renal arteries has not been established. We report a case of abdominal aortic aneurysm complicated by congenital right pelvic kidney in a 72-year-old man. Computed tomography (CT) revealed an abdominal aortic aneurysm with a maximum diameter of 54 mm and a right common iliac aneurysm of 45 mm. In addition, he had a congenital right pelvic kidney and CT angiography identified three right pelvic renal arteries. The upper artery originated from the bifurcation of the terminal aorta and the lower two originated from the right common iliac artery. Three-dimensional CT was helpful for the accurate planning of the operation. Open surgical repair of the aortoiliac aneurysm with a Dacron bifurcated graft replacement was decided and reimplantation of all three right pelvic kidney arteries to the right limb of the graft was also performed. For renal preservation, the right pelvic kidney arteries were perfused with cold Ringer's lactate using a rapid infusion pump and coronary perfusion cannula. The patient's postoperative course was uneventful, and worsening of renal function was not observed. The perfusion of renal arteries with cold Ringer's solution was thought to be a simple and appropriate procedure for renal protection.

[Isolated true aneurysm of the deep femoral artery].

PubMed

Salomon du Mont, L; Holzer, T; Kazandjian, C; Saucy, F; Corpataux, J M; Rinckenbach, S; Déglise, S

2016-07-01

Aneurysms of the deep femoral artery, accounting for 5% of all femoral aneurysms, are uncommon. There is a serious risk of rupture. We report the case of an 83-year-old patient with a painless pulsatile mass in the right groin due to an aneurysm of the deep femoral artery. History taking revealed no cardiovascular risk factors and no other aneurysms at other localizations. The etiology remained unclear because no recent history of local trauma or puncture was found. ACT angiography was performed, revealing a true isolated aneurysm of the deep femoral artery with a diameter of 90mm, beginning 1cm after its origin. There were no signs of rupture or distal emboli. Due to unsuitable anatomy for an endovascular approach, the patient underwent open surgery, with exclusion of the aneurysm and interposition of an 8-mm Dacron graft to preserve deep femoral artery flow. Due to their localization, the diagnosis and the management of aneurysms of the deep femoral artery can be difficult. Options are surgical exclusion or an endovascular approach in the absence of symptoms or as a bridging therapy. If possible, blood flow to the distal deep femoral artery should be maintained, the decision depending also on the patency of the superficial femoral artery. In case of large size, aneurysms of the deep femoral artery should be treated without any delay. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Paresev in flight with pilot Milt Thompson

NASA Technical Reports Server (NTRS)

1964-01-01

This movie clip runs 37 seconds in length and begins with a shot from the chase plane of NASA Dryden test pilot Milt Thompson at the controls of the Paresev, then the onboard view from the pilot's seat and finally bringing the Paresev in for a landing on the dry lakebed at Edwards AFB. The Paresev (Paraglider Rescue Vehicle) was an indirect outgrowth of kite-parachute studies by NACA Langley engineer Francis M. Rogallo. In early 1960's the 'Rogallo wing' seemed an excellent means of returning a spacecraft to Earth. The delta wing design was patented by Mr. Rogallo. In May 1961, Robert R. Gilruth, director of the NASA Space Task Group, requested studies of an inflatable Rogallo-type 'Parawing' for spacecraft. Several companies responded; North American Aviation, Downey, California, produced the most acceptable concept and development was contracted to that company. In November 1961 NASA Headquarters launched a paraglider development program, with Langley doing wind tunnel studies and the NASA Flight Research Center supporting the North American test program. The North American concept was a capsule-type vehicle with a stowed 'parawing' that could be deployed and controlled from within for a landing more like an airplane instead of a 'splash down' in the ocean. The logistics became enormous and the price exorbitant, plus NASA pilots and engineers felt some baseline experience like building a vehicle and flying a Parawing should be accomplished first. The Paresev (Paraglider Research Vehicle) was used to gain in-flight experience with four different membranes (wings), and was not used to develop the more complicated inflatable deployment system. The Paresev was designed by Charles Richard, of the Flight Research Center Vehicle and System Dynamics Branch, with the rest of the team being: engineers, Richard Klein, Gary Layton, John Orahood, and Joe Wilson; from the Maintenance and Manufacturing Branch: Frank Fedor, LeRoy Barto; Victor Horton as Project Manager, with Gary Layton becoming Project Manager later on in the program. Mr. Paul Bikle, Director of the Center, gave instructions that were short and to the point: build a single-seat Paraglider and 'do it quick and cheap.' The Paresev was unpowered, the 'fuselage,' an open framework fabricated of welded 4130 steel tubing, was referred to as a `space frame.' The keel and leading edges of the wings were constructed of 2 1/2-inch diameter aluminum tubing. The leading edge sweep angle was held constant at 50 degrees by a rigid spreader bar. Additional wing structure fabricated of steel tubing ensured structural integrity. Seven weeks after the project was initiated the team rolled out the Paresev 1. It resembled a grown-up tricycle, with a rudimentary seat, an angled tripod mast, and, perched on top of the mast, a Rogallo-type parawing. The pilot sat out in the open, strapped in the seat, with no enclosure of any kind. He controlled the descent rate by tilting the wing fore and aft, and turned by tilting the wing from side to side with a control stick that came from overhead. NASA registered the Paresev, the first NASA research airplane to be constructed totally 'in-house,' with the Federal Aviation Administration on February 12, 1962. Flight testing started immediately. There was one space frame built called the Paresev that used four different wing types. Paresev 1 had a linen membrane, with the control stick coming from overhead in front of the pilots seat. Paresev 1A had a regulation control stick and a Dacron membrane. Paresev 1B had a smaller Dacron membrane with the space frame remaining the same. Paresev 1C used a half-scale version of the inflatable Gemini parawing with a small change to the space frame. All 'space frames,' regardless of the parawing configuration, had a shield with 'Paresev 1-A' and the NASA meatball on the front of the vehicle. After the space frame was completed a sailmaker was asked to sew the wing membrane according to the planform developed by NASA Flight Research Center personnel. He suggested using Dacron instead of the linen fabric chosen, but yielded to the engineer's specifications. A nylon bolt rope was attached in the trailing edge of the 150-square-foot wing membrane. The rope was unrestrained except at the wing tips and was therefore free to equalize the load between the two lobes of the wing. This worked reasonably well, but flight tests proved the wing to be too flexible with it flapping and bulging in alarming ways. The poor membrane design led to trailing edge flutter, with longitudinal and lateral stick forces being severe. A number of different rigging modifications to improve the flying characteristics were tried, but very few were successful and none were predictable. Everything seemed to affect stick forces in the worst way. The fifth flight aloft lasted 10 seconds. On a ground tow the Paresev and pilot fell 10 feet. Considerable damage was done to the Paresev with the pilot, Bruce Peterson, being taken to the base hospital. Injuries sustained by the pilot were not serious. After this accident the Paresev was extensively rebuilt and renamed, Paresev-1A. PARESEV 1-A The sailmaker was asked again to construct a 150-square-foot membrane the way he wanted to. The resulting wing membrane had excellent contours in flight and was made from 6-ounce Dacron. The space frame was rebuilt with more sophistication than the Paresev 1 had been. The shock absorbers were Ford automotive parts, the wing universal joint was a 1948 Pontiac part, and the tires and wheels were from a Cessna 175 aircraft. The overhead stick was replaced with a stick and pulley arrangement that operated more like conventional aircraft controls. This vehicle had much improved stick forces and handling qualities. The instrumentation used to obtain data was quite crude, partially as a result of the desire to keep the program simple and low in cost and also because there was no onboard power. To measure performance, technicians installed a large alpha vane on the wing apex with a scale at the trailing edge that the pilot could read directly. A curved bubble level measured the vehicle attitude, and a Fairchild camera recorded the glide slope. PARESEV 1-B The Paresev 1-B used the Paresev 1-A space frame with a smaller Dacron wing (100 square feet) and was flight tested to evaluate its handling qualities with lower lift-to-drag values. One project NASA engineer described its gliding ability as 'pretty scary.' PARESEV 1-C The space frame of this vehicle remained almost unchanged from the earlier vehicles. However, a new control box gave the pilot the ability to increase or decrease the nitrogen in the inflatable wing supports to compensate for the changing density of the air. Two bottles of nitrogen provided an extra supply of nitrogen. The vehicle featured an inflatable wing. Actually the whole wing was not inflatable; the three chambers that acted as spars and supported the wing inflated. The center spar ran fore and aft and measured 191 inches; two other inflatable spars formed the leading edges. These three compartments were filled with nitrogen under pressure to make them rigid. The Paresev in this configuration was expected to closely approximate the aerodynamic characteristics that would be encountered with the Gemini space capsule, only with a parawing extended. The Paresev was very unstable in flight with this configuration. The first Paresev flights began with tows across the dry lakebed, in 1962, using a NASA vehicle, an International Harvester carry-all (6 cylinder). Eventually ground and airtows were done using a Stearman sport biplane (450 horsepower), a Piper Super Cub (150-180 horsepower), Cessna L-19 (200 horsepower Bird Dog) and a Boeing-Vertol HC-1A. Speed range of the Paresev was about 35 to 65 miles per hour. The Paresev completed nearly 350 flights during a research program from 1962 until 1964. Pilots flying the Paresev included NASA pilots Milton Thompson, Bruce Peterson, and Neil Armstrong from Dryden, Robert Champine from Langley, and Gus Grissom, astronaut, plus North American test pilot Charles Hetzel. The Paresev was legally transferred to the National Air and Space Museum of the Smithsonian Institute, Washington, D.C. Despite its looks, the Paresev was a useful research aircraft that helped develop a new way to fly. Although the Rogallo wing was never used on a spacecraft, it revolutionized the sport of hang gliding, and a different but related kind of wing will be used on the X-38 technology demonstrator for a crew return vehicle from the International Space Station.

Helium-Cooled Black Shroud for Subscale Cryogenic Testing

NASA Technical Reports Server (NTRS)

Tuttle, James; Jackson, Michael; DiPirro, Michael; Francis, John

2011-01-01

This shroud provides a deep-space simulating environment for testing scaled-down models of passively cooling systems for spaceflight optics and instruments. It is used inside a liquid-nitrogen- cooled vacuum chamber, and it is cooled by liquid helium to 5 K. It has an inside geometry of approximately 1.6 m diameter by 0.45 m tall. The inside surfaces of its top and sidewalls have a thermal absorptivity greater than 0.96. The bottom wall has a large central opening that is easily customized to allow a specific test item to extend through it. This enables testing of scale models of realistic passive cooling configurations that feature a very large temperature drop between the deepspace-facing cooled side and the Sun/Earth-facing warm side. This shroud has an innovative thermal closeout of the bottom wall, so that a test sample can have a hot (room temperature) side outside of the shroud, and a cold side inside the shroud. The combination of this closeout and the very black walls keeps radiated heat from the sample s warm end from entering the shroud, reflecting off the walls and heating the sample s cold end. The shroud includes 12 vertical rectangular sheet-copper side panels that are oriented in a circular pattern. Using tabs bent off from their edges, these side panels are bolted to each other and to a steel support ring on which they rest. The removable shroud top is a large copper sheet that rests on, and is bolted to, the support ring when the shroud is closed. The support ring stands on four fiberglass tube legs, which isolate it thermally from the vacuum chamber bottom. The insides of the cooper top and side panels are completely covered with 25- mm-thick aluminum honeycomb panels. This honeycomb is painted black before it is epoxied to the copper surfaces. A spiral-shaped copper tube, clamped at many different locations to the outside of the top copper plate, serves as part of the liquid helium cooling loop. Another copper tube, plumbed in a series to the top plate s tube, is clamped to the sidewall tabs where they are bolted to the support ring. Flowing liquid helium through these tubes cools the entire shroud to 5 K. The entire shroud is wrapped loosely in a layer of double-aluminized Kapton. The support ring s inner diameter is the largest possible hole through which the test item can extend into the shroud. Twelve custom-sized trapezoidal copper sheets extend inward from the support ring to within a few millimeters of the test item. Attached to the inner edge of each of these sheets is a custom-shaped strip of Kapton, which is aluminum- coated on the warm-facing (outer) side, and has thin Dacron netting attached to its cold-facing side. This Kapton rests against the test item, but the Dacron keeps it from making significant thermal contact. The result is a non-contact, radiatively reflective thermal closeout with essentially no gap through which radiation can pass. In this way, the part of the test item outside the shroud can be heated to relatively high temperatures without any radiative heat leaking to the inside.

ENUCLEATION IN MALIGNANT CHOROIDAL MELANOMA - results in 15 years of using a new material in the prosthesis of the orbital cavity

PubMed Central

Tataru, CP; Pop, MD

2012-01-01

Rationale: Enucleation implants are covered with a material that allows the fixation of the extraocular rectus muscles. Usually, the implants are covered in donor sclera, which implies the risk of infection transmission, inflammation and implant rejection, being also an expensive procedure. The new materials used for implant meshing should be tested and a safer and cost effective solution should be researched. Objective: This study presents the results obtained after a 15-year use of an original prosthesis for the reconstruction of the orbital cavity after enucleation surgery. Methods and results: 42 eyes of 42 patients who underwent enucleation surgery for choroidal malignant melanoma were included in the study. The surgical technique was very similar to the classic enucleation, the major difference being the implant of a prosthesis made out of a Polymethyl methacrylate (PMMA) ball covered by a Polyethylene terephthalate (dacron) shell used in cardiovascular surgery. All the patients had a very good technical result, without the inflammation of the orbital cavity, conjunctiva or eyelids, which demonstrates a very high material tolerability and an excellent cosmetic result. Late implant expulsion appeared in 7.14% of the patients (3 cases). Discussion: The particularly good results obtained by using this technique, the absence of an inflammatory reaction after surgery, and the long lasting stability of the implant, recommend the method as being safe, with no major complications and a good esthetic result. AbbreviationsPolymethyl methacrylate (PMMA), Malignant choroidal melanoma (CMM) PMID:22802888

Analytical Models for Variable Density Multilayer Insulation Used in Cryogenic Storage

NASA Technical Reports Server (NTRS)

Hedayat, A.; Hastings, L. J.; Brown, T.

2001-01-01

A unique multilayer insulation concept for orbital cryogenic storage was experimentally evaluated at NASA Marshall Space Flight Center (MSFC) using the Multipurpose Hydrogen Test Bed (MHTB). A combination of foam/Multi layer Insulation (MLI) was used. The MLI (45 layers of Double Aluminized Mylar (DAM) with Dacron net spacers) was designed for an on-orbit storage period of 45 days and included several unique features such as: a variable layer density and larger but fewer DAM perforations for venting during ascent to orbit. The focus of this paper is on analytical modeling of the variable density MLI performance during orbital coast periods. The foam/MLI combination model is considered to have five segments. The first segment represents the foam layer. The second, third, and fourth segments represent the three layers of MLI with different layer densities and number of shields. Finally, the last segment is considered to be a shroud that surrounds the last MLI layer. The hot boundary temperature is allowed to vary from 164 K to 305 K. To simulate MLI performance, two approaches are considered. In the first approach, the variable density MLI is modeled layer by layer while in the second approach, a semi-empirical model is applied. Both models account for thermal radiation between shields, gas conduction, and solid conduction through the separator materials. The heat flux values predicted by each approach are compared for different boundary temperatures and MLI systems with 30, 45, 60, and 75 layers.

Super hydrophilic thin film nitinol demonstrates reduced platelet adhesion compared with commercially available endograft materials.

PubMed

Tulloch, Allan W; Chun, Youngjae; Levi, Daniel S; Mohanchandra, Kotekar P; Carman, Gregory P; Lawrence, Peter F; Rigberg, David A

2011-11-01

Thin film nitinol (TFN) is a novel material with which to cover stents for the treatment of a wide range of vascular disease processes. This study aimed to show that TFN, if treated to produce a super hydrophilic surface, significantly reduces platelet adhesion, potentially rendering covered stents more resistant to thrombosis compared to commercially available materials. TFN was fabricated using a sputter deposition process to produce a 5-μ thin film of uniform thickness. TFN then underwent a surface treatment process to create a super hydrophilic layer. Platelet adhesion studies compared surface treated TFN (S-TFN) to untreated TFN, polytetrafluoroethylene, Dacron, and bulk nitinol. In vivo swine studies examined the placement of an S-TFN covered stent in a 3.5 mm diameter external iliac artery. Angiography confirmed placement, and repeat angiography was performed at 2 wk followed by post mortem histopathology. S-TFN significantly reduced platelet adhesion without any evidence of aggregation compared with all materials studied (P < 0.05). Furthermore, in vivo swine studies demonstrated complete patency of the S-TFN covered stent at 2 wk. Post mortem histopathology showed rapid endothelialization of the S-TFN without excessive neointimal hyperplasia. These results demonstrate that S-TFN significantly reduces platelet adhesion and aggregation compared with commercially available endograft materials. Furthermore, the hydrophilic surface may confer thromboresistance in vivo, suggesting that S-TFN is a possible superior material for covering stents. Copyright © 2011 Elsevier Inc. All rights reserved.

Textile for heart valve prostheses: fabric long-term durability testing.

PubMed

Heim, Frederic; Durand, Bernard; Chakfe, Nabil

2010-01-01

The rapid developments and success in percutaneous vascular surgery over the last two decades with the now common stent grafts implantation, make the noninvasive surgery technique today attractive even for heart valve replacement. Less traumatic for the patient and also less time consuming, percutaneous heart valve replacement is however at its beginning and restricted to end of life patients. The noninvasive procedure expects from the heart valve prosthesis material to be resistant and adapted to folding requirements of the implantation process (catheter). Polyester fabric could be a suited material for heart valve implanted percutaneously. Highly flexible and resistant, polyester fabric proved to be well adapted to the dynamic behavior of a valve and polyester (Dacron) is also widely used for vascular grafts implantation and shows good biocompatibility and durability. However, today there's no data available on long-term durability of fabric used as heart valve material. The purpose of this work is to study the long term behavior of a microdenier polyester fabric construction under combined in vitro flexure and tension fatigue stress. In the novel in vitro testing technique presented, a fabric specimen was subjected to combined flexural and tensile fatigue generated by fluid flow under physiological pressure conditions. The results obtained show how flexural properties change with fatigue time, which reflects directly on the suitability of a fabric in such devices. It was also observed that these fabric structural changes directly influence the in vitro behavior of the textile heart valve prosthesis. (c) 2009 Wiley Periodicals, Inc.

Seeding arterial prostheses with vascular endothelium. The nature of the lining.

PubMed Central

Herring, M B; Dilley, R; Jersild, R A; Boxer, L; Gardner, A; Glover, J

1979-01-01

Arterial prostheses seeded with autogenous vascular endothelium demonstrate a well-organized, cellular, inner lining. To determine the nature of the lining cells, six animals underwent replacement of the infrarenal aorta with Dacron prostheses. During the preparation of three such grafts, endothelium was scraped from the saphenous vein with a steel wool pledget, suspended in chilled Sack's solution, and mixed with blood used to preclot the graft. This suspension was omitted from the three control grafts. After six weeks, the grafts were removed, rinsed and examined. Fluorescent Factor VIII related antigen (F VIII-RA) strongly stained the lining cells. Silver nitrate Haütchen and electron microscopy preparations revealed a lining pattern characteristic of vascular endothelium. Endothelial cell-specific Weibel-Palade bodies were identified in the lining cell cytoplasm. Masson's trichrome staining revealed a relatively collagen-poor connective tissue within the seeded fabric. Transmission electron microscopy disclosed vascular smooth muscle cells between the seeded graft fabric and the lining cells. Vasa vasorum, arising from the outer capsule, penetrated the fabric to supply the inner capsules of the seeded grafts. It is concluded that the cells lining seeded canine arterial prostheses are true vascular endothelium supported by vascular smooth muscle cells, that the lining contains minimal connective tissue, and that vasa vasorum develop. Unseeded control grafts lacked these features. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. Fig. 9. Fig. 10. PMID:464684

Exogenous nitric oxide can control SIRS and downregulate NFkappaB.

PubMed

Lozano, Francisco S; Barros, Marcello B; García-Criado, Francisco J; Gomez-Alonso, Alberto

2005-03-01

Nitric oxide (NO) participates in inflammation and affects almost all steps of its development. Several experimental studies have unveiled the beneficial effects of NO through modulation of the Systemic Inflammatory Response Syndrome (SIRS). In this sense, in the present work we attempted to evaluate the beneficial effects of exogenous NO and its levels of action (biochemical and cellular) in a model of SIRS induced by two sequential insults. Dacron graft implantation (first insult) and subsequent administration of Zymosan A (second insult) in Wistar rats. The animals were divided into four groups: 1) No manipulation (Basal); 2) Laparotomy (L) + mineral oil (Sham); 3) L + Graft-Zymosan (GZ) (Control); and 4) L + GZ + NO (Assay). Determinations: Survival, TNF-alpha, SOA, ICAM-1, and NFkappaB. The model established (Control) induced a mortality rate of 20%. Also, it significantly increased the levels of TNF-alpha (P <0.001) and SOA (P <0.01), ICAM-1 expression, and NFkappaB levels (P <0.05). Treatment with NO reduced mortality to 0%, significantly decreasing TNF-alpha (P <0.001) and SOA (P <0.01) levels, ICAM-1 expression, and NFkappaB levels (P <0.05). The exogenous administration of NO before the two sequential insults controlled SIRS at biochemical level (TNF-alpha, SOA) and at cellular level (transcription) in a lasting manner. The cascade-like interrelationship of both levels and the study design do not allow us the pinpoint the key to its modulation.

Aortic wrapping for a dilated ascending aorta in bicuspid aortic stenosis.

PubMed

Choi, Min Suk; Jeong, Dong Seop; Lee, Hae Young; Sung, Kiick; Kim, Wook Sung; Lee, Young Tak; Park, Pyo Won

2015-01-01

Ascending aorta wrapping is rarely recommended for the management of dilated aorta, because of late complications. The aim of the present study was to analyze the early and late outcomes of the aortic wrapping technique at the time of aortic valve replacement (AVR) for bicuspid aortic stenosis (BAS). Among patients who underwent primary AVR for BAS between 2002 and 2011, 79 who underwent ascending aortic wrapping (wrapping group) were compared with 144 patients who underwent AVR alone. The preoperative ascending aortic diameters were larger in the wrapping group (40.9±4.2 mm vs. 48.6±4.0 mm, P<0.001). Operative technique was to wrap the ascending aorta transversely with a semi-elliptically resected Dacron graft. The follow-up for the wrapping group was 76.5±35.5 (median 71.1) months. There were no early deaths. Early and late morbidity did not differ between groups. The 24 late deaths, including 10 cardiac-related deaths, occurred in the entire group; 3 sudden deaths occurred only in the AVR group. The 10-year overall survival in the wrapping group was higher than the AVR group (88.1±6.8% vs. 80.0±4.6%, P=0.048). No late aortic complications were detected. The aortic diameter was reduced from 49.5±4.1 mm to 45.3±5.0 mm after wrapping (P<0.001). The aortic wrapping technique may be an option for treating a moderately dilated ascending aorta in selected patients undergoing AVR for BAS. Longer follow-up, however, is necessary to verify later complications.

Accelerated healing of cardiovascular textiles promoted by an RGD peptide.

PubMed

Tweden, K S; Harasaki, H; Jones, M; Blevitt, J M; Craig, W S; Pierschbacher, M; Helmus, M N

1995-07-01

Polytetrafluoroethylene (PTFE) and polyethylene terephthalate (Dacron polyester) fabrics are used extensively in cardiovascular devices, e.g. heart valve sewing cuffs and vascular prostheses. While devices containing these fabrics are generally successful, it is recognized that fabrics cause complications prior to tissue ingrowth due to their thrombogenic nature. A surface active synthetic peptide, called PepTite Coating (PepTite), which was modeled after the cell attachment domain of human fibronectin has been marketed as a biocompatible coating. This peptide stimulates cell attachment through the arginine-glycine-aspartic acid (RGD) sequence. Modification of medical implants with PepTite has been shown to promote ingrowth of surrounding cells into the material leading to better tissue integration, reduced inflammation and reduced fibrotic encapsulation. In this study, polyester and PTFE textiles were modified with PepTite. The effectiveness of this coating in enhancing wound healing was investigated in a simple vascular and cardiac valve model. Our results indicate that the RGD-containing peptide, PepTite, promoted the formation of an endothelial-like cell layer on both polyester and PTFE vascular patches in the dog model. PepTite was also found to promote the formation of a significantly thinner neointima (pannus) on polyester as compared to that on its uncoated control. These results were corroborated in the cardiac valve model in which a greater amount of thin pannus and less thrombus were seen on coated polyester sewing cuffs than on control uncoated cuffs. This research shows the promising tissue response to RGD coated textiles and the potential role of this peptide in material passivation via accelerated healing.

Meniscal Scaffolds - Preclinical Evidence to Support their Use: A Systematic Review

PubMed Central

Di Matteo, Berardo; Perdisa, Francesco; Gostynska, Natalia; Kon, Elizaveta; Filardo, Giuseppe; Marcacci, Maurilio

2015-01-01

Arthroscopic meniscal treatment is the most common procedure performed in the orthopedic practice. Current management of meniscal pathology relies on different therapeutic options, ranging from selective meniscectomy, suturing, and to meniscal replacement by using either allografts or scaffolds. The progresses made in the field of regenerative medicine and biomaterials allowed to develop several meniscal substitutes, some of those currently used in the clinical practice. Before reaching the clinical application, these devices necessarily undergo accurate testing in the animal model: the aim of the present manuscript is to systematically review the scientific evidence derived by animal model results for the use of meniscal scaffolds, in order to understand the current state of research in this particular field and to identify the trends at preclinical level that may influence in the near future the clinical practice. Thirty-four papers were included in the present analysis. In 12 cases the meniscal scaffolds were used with cells to further stimulate tissue regeneration. With the exception of some negative reports regarding dacron-based scaffolds, the majority of the trials highlighted that biomaterials and bio-engineered scaffolds are safe and could play a beneficial role in stimulating meniscal healing and in chondral protection. With regard to the benefits of cell augmentation, the evidence is limited to a small number of studies and no conclusive evidence is available. However, preclinical evidence seems to suggest that cells could enhance tissue regeneration with respect to the use of biomaterials alone, and further research should confirm the translational potential of cell-based approach. PMID:26157531

Thermal coupon testing of Load-Bearing Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Heckle, K. W.; Hurd, J.

2014-01-01

Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

[Aorto-bifermoral grafs infection due to Candida parapsilosis. An unusual pathogen].

PubMed

Guevara-Noriega, Kerbi Alejandro; Velescu, Alina; Zaffalon-Espinal, Diana Teresa; Mateos-Torres, Eduardo; Roig-Santamaría, Luis; Clará-Velasco, Albert

Aorto-enteric fistula is a rare and potentially lethal entity. Its presentation may be as an enteric-paraprosthetic fistula, due to injury in the gut caused by direct contact with the vascular prosthesis. We report a case of enteric-paraprosthetic fistulae with the unusual finding of Candida parapsilosis as the only isolated pathogen. A 65-year-old male, smoker, with aortobifemoral revascularisation with dacron due to aortoiliac occlusive disease, and re-intervention for thrombosis of left arm at 6 months. Hospitalisation at 22 months was required due to a toxic syndrome, which was diagnosed as enteric-paraprosthetic fistulae after complementary studies. The graft was removed and an extra-anatomic revascularisation was performed. Microbiology specimens taken from the duodenal segment in contact with the prosthesis showed the prosthetic segment and peri-prosthetic fluid were positive to C. parapsilosis. The finding of C. parapsilosis in all cultures taken during surgery, along with negative blood cultures and no other known sources of infection, is of interest. It is an unusual pathogen with low virulence and limited as regards other Candida species. Our patient had no clinical data common to cases of infection with C. parapsilosis, and the mechanism of graft infection is unknown. Graft infection by C. parapsilosis may be anecdotal. However, its consequences can also be severe. Microbiological tests can be useful to adjust antimicrobial therapy in the post-operative period, but their usefulness for determining the aetiology is doubtful, as it may be just an incidental finding. Copyright © 2016 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

Temporary closure of the abdominal wall by use of silicone rubber sheets after operative repair of ruptured abdominal aortic aneurysms.

PubMed

Akers, D L; Fowl, R J; Kempczinski, R F; Davis, K; Hurst, J M; Uhl, S

1991-07-01

Management of patients after operative repair of abdominal aortic aneurysms can be further complicated if primary closure of the abdominal wall cannot be technically accomplished or is associated with profound increases in intraabdominal and peak inspiratory pressures. We recently treated five patients with ruptured abdominal aortic aneurysms and one patient with a ruptured thoracoabdominal aneurysm whose abdominal incisions had to be closed with a Dacron reinforced, silicone sheet. All patients were hemodynamically unstable either at admission to the hospital or became so during operation. Four patients required the insertion of a silicone rubber sheet at the primary operation because of massive retroperitoneal hematoma or edema of the bowel wall or both. Incisions in two patients were closed primarily, but the patients required reexploration and secondary closure with silicone rubber sheets because of the development of marked increases in peak inspiratory pressures, intraabdominal pressures, and decreased urinary output. Four of the six patients subsequently underwent successful removal of the silicone rubber sheets with delayed primary closure of the abdominal wall, and two others died before removal. The patient with the ruptured thoracoabdominal aneurysm died on postoperative day 20 because of pulmonary sepsis but had a healed abdominal incision. The three surviving patients have been discharged. A silicone rubber sheet may be necessary for closure of the abdominal wall after repair of ruptured abdominal aortic aneurysm in patients where primary abdominal wall closure is impossible or where it results in compromise in respiratory or renal function.

Force-Strain Characteristics and Rupture-Load Capability of Viking-Type Suspension-Line Material Under Dynamic Loading Conditions

NASA Technical Reports Server (NTRS)

Poole, Lamont R.; Councill, Earl L., Jr.

1972-01-01

A series of tests has been conducted to investigate the elastic behavior of Viking-type suspension-line material under dynamic loading conditions. Results indicate that there is a decrease in both rupture-load capability and elongation at rupture as the test strain rate is increased. Preliminary examination of force-strain characteristics indicates that, on the average, the material exhibits some type of viscous effect which results in a greater force being produced, for a particular value of strain, under dynamic loading conditions than that produced under quasi-static loading conditions. A great deal of uncertainty exists in defining a priori the tensile properties of viscoelastic materials, such as nylon or dacron, under dynamic loading conditions. Additional uncertainty enters the picture when woven configurations such as suspension,line material are considered. To eliminate these uncertainties, with respect to the Viking parachute configuration, a test program has been conducted to obtain data on the tensile properties of Viking-type suspension-line material over a wide range of strain rates. Based on preliminary examination of these data, the following conclusions can be drawn: 1. Material rupture-load capability decreases as strain-rate is increased. At strain rates above 75 percent/sec, no rupture loads were observed which would meet the minimum tensile strength specification of 880 pounds. 2. The material, on the average, exhibits some type of viscous effect which, for a particular value of strain, produces a greater load under dynamic loading conditions than that produced under quasi-static loading conditions.

Effect of heparin bonding on catheter-induced fibrin formation and platelet activation.

PubMed

Nichols, A B; Owen, J; Grossman, B A; Marcella, J J; Fleisher, L N; Lee, M M

1984-11-01

Pathologic and experimental evidence indicates that platelet activation and fibrin formation contribute to the pathogenesis of angina pectoris, coronary vasospasm and myocardial infarction. Detection of localized intravascular platelet activation and fibrin formation in vivo by selective blood sampling requires catheters that do not induce coagulation ex vivo. We studied the effect of heparin bonding of catheter surfaces on activation of the coagulation system by cardiovascular catheters. Woven Dacron, polyvinylchloride, and polyurethane catheters were tested and compared with identical catheters with heparin-bonded surfaces in 47 patients undergoing percutaneous cardiac catheterization. Platelet activation was measured by radioimmunoassay of plasma platelet factor 4 (PF4), beta-thromboglobulin (BTG), and thromboxane B2 (TXB2) in blood samples withdrawn through catheters, and fibrin formation was assessed by determination of fibrinopeptide A (FPA) levels. In blood samples collected through conventional catheters, FPA, PF4, BTG, and TXB2 levels were markedly elevated; blood sampling through heparin-bonded catheters had no significant effect on FPA, PF4, BTG, or TXB2 levels. Scanning electron microscopy disclosed extensive platelet aggregates and fibrin strands adherent to the surface of conventional catheters but not to heparin-bonded catheter surfaces. This study demonstrates that (1) collection of blood samples through cardiovascular catheters causes artifactual elevation of FPA, PF4, BTG, and TXB2 levels, and (2) heparin-bonded catheter surfaces effectively prevent catheter-induced platelet alpha-granule release and fibrin formation on catheter surfaces. Heparin-bonded catheters will facilitate investigation of the role of intravascular coagulation in coronary artery disease by eliminating catheter-induced fibrin formation and platelet activation.

Accuracy enhancement of laser induced breakdown spectra using permittivity and size optimized plasma confinement rings.

PubMed

Li, An; Guo, Shuai; Wazir, Nasrullah; Chai, Ke; Liang, Liang; Zhang, Min; Hao, Yan; Nan, Pengfei; Liu, Ruibin

2017-10-30

The inevitable problems in laser induced breakdown spectroscopy are matrix effect and statistical fluctuation of the spectral signal, which can be partly avoided by utilizing a proper confined unit. The dependences of spectral signal enhancement on relative permittivity were studied by varying materials to confine the plasma, which include polytetrafluoroethylene(PTFE), nylon/dacron, silicagel, and nitrile-butadiene rubber (NBR) with the relative permittivity 2.2, ~3.3, 3.6, 8~13, 15~22. We found that higher relative permittivity rings induce stronger enhancement ability, which restricts the energy dissipation of plasma better and due to the reflected electromagnetic wave from the wall of different materials, the electromagnetic field of plasma can be well confined and makes the distribution of plasma more orderly. The spectral intensities of the characteristic lines Si I 243.5 nm and Si I 263.1 nm increased approximately 2 times with relative permittivity values from 2.2 to ~20. The size dependent enhancement of PTFE was further checked and the maximum gain was realized by using a confinement ring with a diameter size of 5 mm and a height of 3 mm (D5mmH3mm), and the rings with D2mmH1mm and D3mmH2mm also show higher enhancement factor. In view of peak shift, peak lost and accidental peaks in the obtained spectra were properly treated in data progressing; the spectral fluctuation decreased drastically for various materials with different relative permittivities as confined units, which means the core of plasma is stabilized, attributing to the confinement effect. Furthermore, the quantitative analysis in coal shows wonderful results-the prediction fitting coefficient R 2 reaches 0.98 for ash and 0.99 for both volatile and carbon.

An overview of thin film nitinol endovascular devices.

PubMed

Shayan, Mahdis; Chun, Youngjae

2015-07-01

Thin film nitinol has unique mechanical properties (e.g., superelasticity), excellent biocompatibility, and ultra-smooth surface, as well as shape memory behavior. All these features along with its low-profile physical dimension (i.e., a few micrometers thick) make this material an ideal candidate in developing low-profile medical devices (e.g., endovascular devices). Thin film nitinol-based devices can be collapsed and inserted in remarkably smaller diameter catheters for a wide range of catheter-based procedures; therefore, it can be easily delivered through highly tortuous or narrow vascular system. A high-quality thin film nitinol can be fabricated by vacuum sputter deposition technique. Micromachining techniques were used to create micro patterns on the thin film nitinol to provide fenestrations for nutrition and oxygen transport and to increase the device's flexibility for the devices used as thin film nitinol covered stent. In addition, a new surface treatment method has been developed for improving the hemocompatibility of thin film nitinol when it is used as a graft material in endovascular devices. Both in vitro and in vivo test data demonstrated a superior hemocompatibility of the thin film nitinol when compared with commercially available endovascular graft materials such as ePTFE or Dacron polyester. Promising features like these have motivated the development of thin film nitinol as a novel biomaterial for creating endovascular devices such as stent grafts, neurovascular flow diverters, and heart valves. This review focuses on thin film nitinol fabrication processes, mechanical and biological properties of the material, as well as current and potential thin film nitinol medical applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bockron as a Medium of Learning in The Process of Inquiry based Learning to Improve Science Process Skills of Junior High School Students in Growth and Development Concept

NASA Astrophysics Data System (ADS)

Mayasari, D.

2017-02-01

Investigative research on Influence of bockron as a medium of learning in process of inquiry-based learning to the development of science process skills on the concept of growth and development. This research was done in an effort to follow up underdeveloped skills of observing, communicating andconclude on students. This research was conducted using classroom action research (PTK), which consisted of 3 cycles. Cycle 1 students observe differences in growth and development, cycle 2 students measure the growth rate, cycle 3 students observe factors that influence growth and development, In these three cycles is used as a planting medium bocron (bottles and dacron). It involves 8th grade junior high-school students of 14-15 years old as research subjects in six meetings. Indicators of process skill include observation, communication, interpretation and inference. Data is collected through students’ work sheets, written tests and observation. Processing of the data to see N-Gain used Microsoft Excel 2007, and the results showed that an increase in science process skills with a value of medium N-Gain (0,63). Bokron learning medium easily and cheaply obtainable around the students, particularly those in urban areas is quite difficult to get land to be used as aplanting medium. In addition to observation of growth and development, bokron media can also be used to observe the motion in plants. The use bokron as a learning medium can train and develop science process skills, attitude and scientific method also gives students concrete experience of the process of growth and development in plants.

Complications at the Proximal Landing Zone of Endovascular Stent Grafts Deployed in Surgically Replaced Ascending Aorta.

PubMed

Kotha, Vamshi K; Herget, Eric J; Appoo, Jehangir J

2016-11-01

The ascending aorta, with its hostile angulations and forces, is the next frontier in the evolution of endovascular surgery. Type II hybrid arch repair, involving surgical replacement of the ascending aorta, arch debranching, and stent graft deployment in the ascending aortic graft, offers an opportunity to study the behavior of an endovascular prosthesis in the ascending aorta. We report complications seen at the proximal landing zone after type II hybrid arch repair. A dedicated imaging protocol was used to monitor 20 consecutive patients who underwent type II hybrid arch repair at a single center from June 2009 to July 2014. Mean age was 66 years (range, 47 to 82 years). Mean imaging follow-up was 34 months (range, 12 to 64 months). There was 1 operative death (5%). Bird beaking (>5 mm of nonapposition) of the stent graft at the proximal landing zone occurred in 12 patients, and >20 mm of bird beaking occurred in 7 patients. Proximal landing zone complications occurred in 4 patients (20%), comprising 2 type Ia endoleaks, 1 graft migration, and 1 graft infolding detected on postoperative days 4, 11, 5, and 755, respectively. Three patients underwent endovascular reintervention for proximal landing zone complications. There were no late deaths. Thoracic aortic stent grafts may be prone to proximal landing zone complications when deployed in the ascending aorta. Bird beaking is common when endografts are deployed in the Dacron (DuPont, Wilmington, DE) ascending aorta. Angulation issues will likely need to be overcome by stent graft refinement to enable future closed chest approaches to the ascending aorta. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Aortic root replacement using a biovalsalva prosthesis in comparison to a "handsewn" composite bioprosthesis.

PubMed

Moorjani, Narain; Modi, Amit; Mattam, Kavita; Barlow, Clifford; Tsang, Geoffrey; Haw, Marcus; Livesey, Steven; Ohri, Sunil

2010-05-01

The Biovalsalva aortic root prosthesis incorporates an Elan porcine stentless biological aortic valve suspended within a triple-layered vascular conduit with preformed aortic sinuses of Valsalva. This study compared implantation of the Biovalsalva prosthesis with a "handsewn" composite bioprosthetic graft (CE Perimount bovine bioprosthesis anastomosed to a gelatin-impregnated gelweave Dacron graft). Between December 2004 and January 2009, 39 patients underwent elective or urgent aortic root replacement (modified Bentall procedure with coronary button reimplantation) using a Biovalsalva (n = 21) or a handsewn bioprosthesis (n = 18) for aortic root dilatation. There was no significant difference in the preoperative variables between the two study groups including age (70.7 +/- 1.7 vs. 67.6 +/- 2.9 years, p > 0.05). There was no in-hospital mortality. Three patients in each group underwent concomitant aortic hemi-arch replacement. Patients who underwent Biovalsalva implantation had a reduced need for transfusion of blood (1.25 +/- 0.32 vs. 3.17 +/- 0.71 units, p < 0.05) and fresh frozen plasma (2.78 +/- 0.39 vs. 1.85 +/- 0.31, p < 0.05), and reduced mediastinal blood loss (416 +/- 52 vs. 583 +/- 74 mL, p < 0.05) compared to those with a handsewn bioprosthesis. Cardiopulmonary bypass time (141 +/- 6 vs. 170 +/- 17 minutes, p = NS) and aortic cross-clamp time (113 +/- 6 vs. 115 +/- 7 minutes, p = NS) were similar. Postoperative echocardiography demonstrated excellent hemodynamic function of the Biovalsalva prosthesis (mean size 25.1 +/- 0.4 mm valved conduit) with a peak pressure gradient of 26.2 +/- 1.9 mmHg and no or trivial valvular regurgitation. The Biovalsalva prosthesis should be considered for patients requiring a biological aortic root replacement. It offers an "off-the-shelf" preassembled composite biological valve conduit with excellent hemostatic and hemodynamic properties.

Extracellular matrix scaffold as a tubular graft for ascending aorta aneurysm repair.

PubMed

Abu Saleh, Walid K; Al Jabbari, Odeaa; Grande-Allen, Jane; Ramchandani, Mahesh

2015-08-01

Although extracellular xenograft repair has produced encouraging results when applied to cardiac, valvular, and specific aortic defects, its employment as a tube graft to replace the ascending aorta has not been reported. We describe a patient who underwent resection and replacement of an infected ascending aortic graft with an extracellular matrix conduit. The patient did well, but 14 months later developed a pseudoaneurysm from the staple line used to construct the extracellular matrix conduit. The patient underwent a repeat sternotomy and removal of the graft. Because of the increased risk of graft failure, a homograft was felt to be more appropriate in this setting. Ultimately, we were unable to implant the homograft because it was too small for the aortic root; therefore we decided to construct a tubular graft from Cormatrix extracellular matrix (CorMatrix, Roswell, GA, USA). Fourteen months later, he presented with shortness of breath. Computed tomography scan revealed a 3.5 cm pseudoaneurysm of the ascending aorta. It appeared as if there was a disruption of the staple line in the extra cellular matrix graft. The plan was to replace it with a Dacron graft. The Cormatrix graft material was removed and sent for culture and histological analysis. A 28-mm Gel weave graft (Terumo Cardiovascular Systems, Ann Arbor, MI, USA) was implanted. The patient tolerated the procedure well with good hemodynamics. Our experience suggests that the superior strength, handling characteristics, and resistance to infection make extra cellular matrix scaffold a possible alternative conduit to cryopreserved homografts. Applicability as an aortic conduit merits further investigation to better understand behavior of extra cellular matrix in this situation. © 2015 Wiley Periodicals, Inc.

Modified Ross procedure using a conduit with a synthetic valve.

PubMed

Takabayashi, Shin; Kado, Hideaki; Shiokawa, Yuichi; Fukae, Kouji; Nakano, Toshihide

2004-12-01

In the Ross procedure, a homograft conduit is commonly used in place of an autotransplanted pulmonary valve. Homograft availability may be a problem and has resulted in a search for alternatives. We performed a modified Ross procedure for right ventricular outflow tract reconstruction with a synthetic valved conduit as an alternative to homograft. Our early results of valvular and right ventricular function were evaluated in patients who used a conduit with a synthetic valve. Subjects consisted of 11 patients, who ranged in age from 5 to 22 years (12.0+/-4.9), and whose body weight ranged from 15.1 to 52.5 (34.3+/-14.4) kg. Indications for surgery were aortic stenosis (n=3), aortic stenosis and regurgitation (n=4), and aortic regurgitation (n=4). Right ventricular outflow tract reconstruction was performed using a hand-fashioned valved conduit prepared by sewing a 0.1 mm thick polytetrafluoroethylene sheet onto the luminal cavity of the 20-28 mm conduit. A conduit made with polytetrafluoroethylene was used in 8 patients, and a Dacron graft was used in 3 patients. There was no in-hospital or late mortality and angiocardiography at discharge revealed that all artificial valves remained active. The mean right atrial pressure and right ventricular end-diastolic pressure were not statistically different from preoperative values. The latest echocardiography (mean interval, 12.6 months) revealed that a mean pressure gradient across the synthetic valve was 11.4+/-11.1 mmHg and none of the patients had moderate or severe regurgitation. We demonstrated that a modified Ross procedure for right ventricular outflow tract reconstruction using a conduit with an appropriate synthetic valve is particularly effective in older children.

Ultraviolet Testing of Space Suit Materials for Mars

NASA Technical Reports Server (NTRS)

Larson, Kristine; Fries, Marc

2017-01-01

Human missions to Mars may require radical changes in the approach to extra-vehicular (EVA) suit design. A major challenge is the balance of building a suit robust enough to complete multiple EVAs under intense ultraviolet (UV) light exposure without losing mechanical strength or compromising the suit's mobility. To study how the materials degrade on Mars in-situ, the Jet Propulsion Laboratory (JPL) invited the Advanced Space Suit team at NASA's Johnson Space Center (JSC) to place space suit materials on the Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals (SHERLOC) instrument's calibration target of the Mars 2020 rover. In order to select materials for the rover and understand the effects from Mars equivalent UV exposure, JSC conducted ground testing on both current and new space suit materials when exposed to 2500 hours of Mars mission equivalent UV. To complete this testing, JSC partnered with NASA's Marshall Space Flight Center to utilize their UV vacuum chambers. Materials tested were Orthofabric, polycarbonate, Teflon, Dacron, Vectran, spectra, bladder, nGimat coated Teflon, and nGimat coated Orthofabric. All samples were measured for mass, tensile strength, and chemical composition before and after radiation. Mass loss was insignificant (less than 0.5%) among the materials. Most materials loss tensile strength after radiation and became more brittle with a loss of elongation. Changes in chemical composition were seen in all radiated materials through Spectral Analysis. Results from this testing helped select the materials that will fly on the Mars 2020 rover. In addition, JSC can use this data to create a correlation to the chemical changes after radiation-which is what the rover will send back while on Mars-to the mechanical changes, such as tensile strength.

Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels

NASA Astrophysics Data System (ADS)

Lee, Carol Hsiu-Yueh

Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (< 6 mm) grafts where thrombosis and intimal hyperplasia are common in graft failure. With the use of a synthetic biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

Early Results of Rheumatic Mitral Valve Repair.

PubMed

Petrone, Giuseppe; Theodoropoulos, Panagiotis; Punjabi, Prakash P

2016-11-01

Mitral valve repair (MVr) in rheumatic heart disease (RHD) remains challenging. The present authors' surgical experience of MVr in 56 patients with RHD operated in between January 2011 and September 2014 is reported. Among the patients (mean age 32 ± 11 years), 11 were in NYHA functional class II, 32 in class III, and seven in class IV. An adequate or oversized autologous pericardial patch was sutured to extend the coaptating edge of both the anterior leaflet (in 18 patients) and the posterior leaflet (in 30 patients). Neochordae were implanted as needed (n = 43), and leaflet thinning (n = 13), commissurotomy (n = 15) and chordal splitting (n = 9) were also performed. A rigid annuloplasty ring was implanted in 32 patients, and in 24 patients a complete flexible annuloplasty ring made from pericardium, 4 mm Gore-Tex tube graft or a Dacron patch was constructed. Repair was not attempted in 16 patients, with replacement using a mechanical bileaflet prosthesis being considered the only option. Intraoperative post-repair transesophageal echocardiography demonstrated competency, with trivial mitral regurgitation (MR) up to grade I in all patients and a minimum coaptation depth ≥5 mm. There were no intraoperative or in-hospital deaths. Clinical and echocardiographic evaluations were performed up to six weeks after surgery, at which time 51 patients were in NYHA classes I-II and five were in class III. Residual mild MR up to grade I was identified in six patients. No recurrence of MR was observed in any of the patients, and no patients were reoperated on. The lack of adequate access to anticoagulation medication and monitoring, in addition to religious/cultural bias to the type of prosthetic valve used in low-income countries, necessitates an increase in the numbers of rheumatic MVr.

Investigation into the optimal prosthetic material for wound healing of abdominal wall defects

PubMed Central

Akcakaya, Adem; Aydogdu, Ibrahim; Citgez, Bulent

2018-01-01

The purpose of this experimental study is to investigate and compare the effects of prosthetic materials used for wound healing of abdominal wall hernias. A total of 60 rats were divided into five equal groups: Group I, control subjected to laparotomy; group II, abdominal wall defect 3×2 cm+polypropylene (PP) mesh; group III, abdominal wall defect 3×2 cm+PP mesh+hyaluronate and carboxymethylcellulose (H-CMC; Seprafilm®); group IV, abdominal wall defect 3×2 cm+polytetrafluoroethylene (PTFE; Composix™); and group V, abdominal wall defect 3×2 cm+polyethylene terephthalate (PET; Dacron®). A total of 14 days after the surgery, rats were sacrificed and the meshes with the surrounding tissue were extracted in block. The breaking strength of the mesh from the fascia was recorded. The healing tissue was examined with the index of histopathology and the hydroxyproline value was analyzed using the Switzer method. Both the breaking strength and histopathological index of the wound healing were significantly improved in groups II and III compared with that in groups IV and V (P<0.001). Hydroxyproline values were the highest in group I (P<0.001). There was also a statistically significant difference between groups II and IV, and group V and the other groups (P<0.001). The present findings demonstrated that PP mesh and PP mesh+H-CMC had a superior breaking strength and improved histopathologic indices compared with PTFE and PET. Furthermore, hydroxyproline values were the lowest in the PET group. In conclusion, wound healing was improved in the PP mesh group and the PP mesh+H-CMC group compared with the PTFE and PET groups according to the present study parameters. PMID:29399133

Concordance of human papillomavirus types detected on the surface and in the tissue of genital lesions in men.

PubMed

Anic, Gabriella M; Messina, Jane L; Stoler, Mark H; Rollison, Dana E; Stockwell, Heather; Villa, Luisa L; Lazcano-Ponce, Eduardo; Gage, Christine; Silva, Roberto Jose C; Baggio, Maria L; Salmerón, Jorge; Giuliano, Anna R

2013-09-01

Swabbing the surface of a genital lesion to obtain a sample for HPV DNA testing is less invasive than a biopsy, but may not represent HPV types present in the lesion tissue. The objective of this study was to examine the concordance of HPV types detected in swab and biopsy samples from 165 genital lesions from men ages 18-70. Lesions included 90 condyloma, 10 penile intraepithelial neoplasia (PeIN), 23 non-condyloma with a known histology, and 42 lesions with an undetermined histology. All lesions were sampled by swabbing the surface of the lesion with a pre-wetted Dacron swab and taking a shave biopsy. HPV genotyping was performed using Linear Array for swab samples and INNO-LiPA for biopsy samples. The kappa and McNemar statistics were used to compare the concordance of detecting HPV types in swab and biopsy samples. Both sampling methods had high agreement for detection of HPV DNA in condyloma (87.8% agreement) and PeIN (100% agreement). There was also high concordance for detection of HPV16 (kappa = 1.00) and HPV18 (kappa = 1.00) in PeIN, however, agreement was low to moderate for detecting HPV6 (kappa = 0.31) and HPV11 (kappa = 0.56) in condyloma. Low to moderate agreement was also observed between sampling methods for detecting individual HPV types in the non-condyloma and lesions with an indefinite histology. The results suggest that obtaining a biopsy in addition to swabbing the surface of a lesion may provide additional information about specific HVP types associated with male genital lesions. Copyright © 2013 Wiley Periodicals, Inc.

Hyper III on ramp, front view

NASA Technical Reports Server (NTRS)

1969-01-01

The Hyper III was a low-cost test vehicle for an advanced lifting-body shape. Like the earlier M2-F1, it was a 'homebuilt' research aircraft, i.e., built at the Flight Research Center (FRC), later redesignated the Dryden Flight Research Center. It had a steel-tube frame covered with Dacron, a fiberglass nose, sheet aluminum fins, and a wing from an HP-11 sailplane. Construction was by volunteers at the FRC. Although the Hyper III was to be flown remotely in its initial tests, it was fitted with a cockpit for a pilot. On the Hyper III's only flight, it was towed aloft attached to a Navy SH-3 helicopter by a 400-foot cable. NASA research pilot Bruce Peterson flew the SH-3. After he released the Hyper III from the cable, NASA research pilot Milt Thompson flew the vehicle by radio control until the final approach when Dick Fischer took over control using a model-airplane radio-control box. The Hyper III flared, then landed and slid to a stop on Rogers Dry Lakebed. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross-range reentry vehicles studied at Langley. (Hypersonic means Mach 5--five times the speed of sound--or faster; cross-range means able to fly a considerable distance to the left or right of the initial reentry path.) The FRC added a small, deployable, skewed wing to compensate for the shape's extremely low glide ratio. Shop personnel built the 32-foot-long Hyper III and covered its tubular frame with dacron, aluminum, and fiberglass, for about $6,500. Hyper III employed the same '8-ball' attitude indicator developed for control-room use when flying the X-15, two model-airplane receivers to command the vehicle's hydraulic controls, and a telemetry system (surplus from the X-15 program) to transmit 12 channels of data to the ground not only for display and control but for data analysis. Dropped from a helicopter at 10,000 feet, Hyper III flew under the control of research pilot Milt Thompson to a near landing using instruments for control. When the vehicle was close to the ground, he handed the vehicle off to experienced model pilot Dick Fischer for a visual landing using standard controls. The flight demonstrated the feasibility of remotely piloting research vehicles and, among other things, that control of the vehicle in roll was much better than predicted and that the vehicle had a much lower lift-to-drag ratio than predicted (a maximum of 4.0 rather than 5.0). Pilot Milt Thompson exhibited some suprising reactions during the Hyper III flight; he behaved as if he were in the cockpit of an actual research aircraft. 'I was really stimulated emotionally and physically in exactly the same manner that I have been during actual first flights.' 'Flying the Hyper III from a ground cockpit was just as dramatic as an actual flight in any of the other vehicles....responsibility rather than fear of personal safety is the real emotional driver. I have never come out of a simulator emtionally and physically tired as is often the case after a test flight in a research aircraft. I was emotionally and physically tired after a 3-minute flight of the Hyper III.'

Compliant electrospun silk fibroin tubes for small vessel bypass grafting.

PubMed

Marelli, Benedetto; Alessandrino, Antonio; Farè, Silvia; Freddi, Giuliano; Mantovani, Diego; Tanzi, Maria Cristina

2010-10-01

Processing silk fibroin (SF) by electrospinning offers a very attractive opportunity for producing three-dimensional nanofibrillar matrices in tubular form, which may be useful for a biomimetic approach to small calibre vessel regeneration. Bypass grafting of small calibre vessels, with a diameter less than 6mm, is performed mainly using autografts, like the saphenous vein or internal mammary artery. At present no polymeric grafts made of SF are commercially available, mainly due to inadequate properties (low compliance and lack of endothelium cells). The aim of this work was to electrospin SF into tubular structures (Ø=6mm) for small calibre vessel grafting, characterize the morphological, chemico-physical and mechanical properties of the electrospun SF structures and to validate their potential to interact with cells. The morphological properties of electrospun SF nanofibres were investigated by scanning electron microscopy. Chemico-physical analyses revealed an increase in the crystallinity of the structure of SF nanofibres on methanol treatment. Mechanical tests, i.e. compliance and burst pressure measurements, of the electrospun SF tubes showed that the inner pressure to radial deformation ratio was linear for elongation up to 15% and pressure up to 400 mm Hg. The mean compliance value between 80 and 120 mm Hg was higher than the values reported for both Goretex(R) and Dacron(R) grafts and for bovine heterografts, but still slightly lower than those of saphenous and umbilical vein, which nowadays represent the gold standard for the replacement of small calibre arteries. The electrospun tubes resisted up to 575+/-17 mmHg, which is more than four times the upper physiological pressure of 120 mmHg and more than twice the pathological upper pressures (range 180-220 mmHg). The in vitro tests showed a good cytocompatibility of the electrospun SF tubes. Therefore, the electrospun SF tubes developed within this work represent a suitable candidate for small calibre blood vessel replacement. 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Prospective Randomized Trial of Carotid Endarterectomy With Polytetrafluoroethylene Versus Collagen-Impregnated Dacron (Hemashield) Patching: Late Follow-Up

PubMed Central

AbuRahma, Ali F.; Hopkins, Eric S.; Robinson, Patrick A.; Deel, John T.; Agarwal, Samir

2003-01-01

Objective To compare the late clinical outcome and incidence of recurrent stenosis after carotid endarterectomy (CEA) with polytetrafluoroethylene (PTFE) versus Hemashield patching. Summary Background Data Several randomized trials have confirmed the advantages of patching over primary closure when performing CEA. Methods Two hundred CEAs (180 patients) were randomized into 100 with PTFE patching and 100 with Hemashield. All patients underwent postoperative color duplex ultrasounds at 1, 6, and 12 months, and every year thereafter. The mean follow-up was 26 months. Kaplan-Meier analysis was used to estimate the risk of re-stenosis, stroke, and stroke-free survival. A multivariate analysis of various risk factors was also done. Results Demographic and clinical characteristics were similar in both groups. The incidence of all ipsilateral strokes (early and late) was 8% (7% perioperative) for Hemashield versus 0% for PTFE patching. Both groups had similar mortality rates. The cumulative stroke-free rates at 6, 12, 24, and 36 months were 93%, 93%, 93%, and 89% for Hemashield versus 100%, 100%, 100%, and 100% for PTFE patching. The cumulative stroke-free survival rates at 6, 12, 24, and 36 months were 90%, 89%, 87%, and 79% for Hemashield versus 98%, 98%, 92%, and 92% for PTFE patching. Kaplan-Meier analysis also showed that freedom from 50% or greater re-stenosis at 6, 12, 24, and 36 months was 89%, 81%, 73%, and 66% for Hemashield versus 100%, 100%, 100%, and 92% for PTFE. Similarly, the freedom from 70% or greater re-stenosis at 6, 12, 24, and 36 months was 93%, 91%, 86%, and 78% for Hemashield versus 100%, 100%, 100%, and 100% for PTFE. Univariate and multivariate analyses of demographic and preoperative risk factors showed that only Hemashield was significantly associated with a higher incidence of 70% or greater recurrent stenosis. Conclusions PTFE patching was superior to Hemashield in lowering the incidence of postoperative ipsilateral strokes and late recurrent stenosis. PMID:12796586

Estimation of hysteretic losses for MgB2 tapes under the operating conditions of a generator

NASA Astrophysics Data System (ADS)

Vargas-Llanos, Carlos Roberto; Zermeño, Víctor M. R.; Sanz, Santiago; Trillaud, Frederic; Grilli, Francesco

2016-03-01

Hysteretic losses in the MgB2 wound superconducting coils of a 550 kW synchronous hybrid scaled generator were estimated as part of the European project SUPRAPOWER led by the Spanish Fundación Tecnalia Research & Innovation. Particular interest was given to the losses caused by the magnetic flux ripples in the rotor coils originating from the conventional stator during nominal operation. To compute these losses, a 2D finite element analysis was conducted and Maxwell’s equations written in the H-formulation were solved considering the nonlinear material properties of the conductor materials. The modeled tapes are made of multiple MgB2 filaments embedded in a Ni matrix and soldered to a high purity copper strip and insulated with Dacron braid. Three geometrical models of single tape cross sections of decreasing complexity were studied: (1) the first model reproduced closely the actual cross section obtained from tape micrographs. (2) The second model was obtained from the computed elasto-plastic deformation of a round Ni wire. (3) The third model was based on a simplified cross section with the superconducting filaments bundled in a single elliptical bulky structure. The last geometry allowed the validation of the modeling technique by comparing numerical losses with results from well-established analytical expressions. Additionally, the following cases of filament transpositions of the multi-filamentary tape were studied: no transposition, partial and full transposition; thereby improving understanding of the relevance of the tape fabrication process on the magnitude of the determination of ac losses. Finally, choosing the right level of geometrical detail, the following operational regimes of the machine and its impact on individual superconducting tape losses in the rotor were studied: bias-dc current, ramping current under ramping background field and magnetic flux ripples under dc background current and field.

Cyclodextrin modified PLLA parietal reinforcement implant with prolonged antibacterial activity.

PubMed

Vermet, G; Degoutin, S; Chai, F; Maton, M; Flores, C; Neut, C; Danjou, P E; Martel, B; Blanchemain, N

2017-04-15

The use of textile meshes in hernia repair is widespread in visceral surgery. Though, mesh infection is a complication that may prolong the patient recovery period and consequently presents an impact on public health economy. Such concern can be avoided thanks to a local and extended antibiotic release on the operative site. In recent developments, poly-l-lactic acid (PLLA) has been used in complement of polyethyleneterephthalate (Dacron®) (PET) or polypropylene (PP) yarns in the manufacture of semi-resorbable parietal implants. The goal of the present study consisted in assigning drug reservoir properties and prolonged antibacterial effect to a 100% PLLA knit through its functionalization with a cyclodextrin polymer (polyCD) and activation with ciprofloxacin. The study focused i) on the control of degree of polyCD functionalization of the PLLA support and on its physical and biological characterization by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and cell viability, ii) on the understanding of drug/meshes interaction using mathematic model and iii) on the correlation between drug release studies in phosphate buffer saline (PBS) and microbiological evaluation of meshes and release medium against E. coli and S. aureus. All above mentioned tests highlighted the contribution of polyCD on the improved performances of the resulting antibacterial implantable material. 1. We managed for the first time, with well-defined parameters in terms of temperature and time of treatment, to functionalize a bio-absorbable synthetic material to improve drug sorption and drug release properties without affecting its mechanical properties. 2. We analyzed for the first time the degradation of our coating products by mass spectroscopy to show that only citrate and cyclodextrin residues (and glucose units) without any cytotoxicity are formed. 3. We managed to improve the mechanical properties of the PLA with the cyclodextrin polymer to form a composite. The assembly (cyclodextrin polymer and PLLA) remains biodegradable. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Feasibility Study of a Novel Thoraco-abdominal Aortic Hybrid Device (SPIDER-graft) in a Translational Pig Model.

PubMed

Debus, Eike S; Kölbel, Tilo; Duprée, Anna; Daum, Günter; Sandhu, Harleen K; Manzoni, Daniel; Wipper, Sabine H

2018-02-01

The hybrid SPIDER-graft consists of a proximal descending aortic stent graft and a conventional six branched Dacron graft for open abdominal aortic repair. Technical feasibility with regard to avoiding thoracotomy and extracorporeal circulation (ECC) during thoraco-abdominal aortic hybrid repair and peri-procedural safety of this novel device are unknown. This was a feasibility and safety study in domestic pigs (75-85 kg). The abdominal aorta including iliac bifurcation, left renal artery, and visceral arteries were exposed via retroperitoneal access. The right iliac branch was first temporarily anastomosed end to side to the distal aorta via partial clamping. During inflow reduction and infra-coeliac cross-clamping, the coeliac trunk (CT) was divided and the proximal stent graft portion of the SPIDER-graft was deployed into the descending aorta via the CT ostium. Retrograde visceral and antegrade aorto-iliac blood flow was maintained via the iliac side branch. The visceral, renal, and iliac arteries were sequentially anastomosed, finally replacing the first iliac end to side anastomosis. Technical success, blood flow, periods of ischaemia, and peri-procedural complications were evaluated after intra-operative completion angiography and post-operative computed tomography angiography. Six animals underwent successful thoracic stent graft deployment and distal open reconstruction without peri-operative death. The median thoracic graft implantation time was 4.5 min, and the median ischaemia times before reperfusion were 10 min for the CT, 8 min for the superior mesenteric artery, 13 min for the right renal artery, and 22 min for the left renal artery. Angiography demonstrated appropriate graft implantation and blood flow measurements confirmed sufficient blood flow through all side branches. In this translational pig model, thoraco-abdominal hybrid repair using the novel SPIDER-graft was successful in avoiding thoracotomy and ECC. Technical feasibility and safety appear promising, but need to be reassessed in humans. Copyright © 2017. Published by Elsevier Ltd.

Short communication: Effect of on-farm feeding practices on rumen protected lysine products.

PubMed

Ji, P; Tucker, H A; Clark, R E; Miura, M; Ballard, C S

2016-02-01

Two independent studies were conducted to determine whether mechanical mixing of total mixed ration (TMR) or TMR dry matter alters Lys release from 6 rumen-protected Lys (RPL) products (A, B, C, D, E, and F). In the first study, routine mixing procedures were simulated to determine if inclusion of RPL products in TMR altered in situ release of Lys. Following mixing, Dacron bags containing RPL products were ruminally incubated for 0, 6, 12, or 24 h to determine Lys release. The second study occurred independently of the first, in which Lys release from RPL products was evaluated when incorporated into a TMR that differed in dry matter (DM) content. Bags containing TMR and RPL product mixture were stored at room temperature for 0, 6, 18, and 24 h to simulate RPL product exposure to TMR when mixed and delivered once per day. Concentration of free Lys in both studies was determined using ultra-performance liquid chromatography. Following mechanical mixing, ruminal Lys release was significantly greater for C and tended to increase for F. Mechanical mixing did not alter ruminal Lys release from other RPL products evaluated. Hours of ruminal incubation significantly altered Lys release for all products evaluated, and a significant interaction of mechanical mixing and hours of ruminal incubation was observed for A and C. Exposure to lower TMR DM (40.5 versus 51.8%) significantly increased Lys release from B but did not alter Lys release from the other RPL products evaluated. Moreover, time of exposure to TMR significantly increased Lys release from all RPL products evaluated, and a significant interaction of TMR DM and time of exposure to TMR was observed for B and E. These data suggest mechanical mixing and variation in TMR DM may compromise the rumen protection of RPL products; therefore, on-farm feeding practices may alter efficacy of RPL products in dairy rations. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The Efficacy of the Quorum Sensing Inhibitor FS8 and Tigecycline in Preventing Prosthesis Biofilm in an Animal Model of Staphylococcal Infection

PubMed Central

Simonetti, Oriana; Cirioni, Oscar; Mocchegiani, Federico; Cacciatore, Ivana; Silvestri, Carmela; Baldassarre, Leonardo; Orlando, Fiorenza; Castelli, Pamela; Provinciali, Mauro; Vivarelli, Marco; Fornasari, Erika; Giacometti, Andrea; Offidani, Annamaria

2013-01-01

We investigated the efficacy of tigecycline and FS8, alone or combined, in preventing prosthesis biofilm in a rat model of staphylococcal vascular graft infection. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2 × 107 colony-forming units of Staphylococcus aureus, strain Smith diffuse. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis, and three contaminated groups that received: (i) intraperitoneal tigecycline, (ii) FS8-soaked graft, and (iii) tigecycline plus FS8-soaked graft, respectively. Each group included 15 animals. The infection burden was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro binding-study was performed to quantify the how much FS8 was coated to the surface of the prosthesis. Tigecycline, combined with FS8, against the adherent bacteria showed MICs (2.00 mg/L) and MBCs (4.00 mg/L) four-fold lower with respect to tigecycline alone in in vitro studies. The rat groups treated with tigecycline showed the lowest bacterial numbers (4.4 × 104 ± 1.2 × 104 CFU/mL). The FS8-treated group showed a good activity and significant differences compared to control group with bacterial numbers of 6.8 × 104 ± 2.0 × 104 CFU/mL. A stronger inhibition of bacterial growth was observed in rats treated with a combined FS8 and tigecycline therapy than in those that were singly treated with bacterial numbers of 101 CFU/mL graft. In conclusion, the ability to affect biofilm formation as well, its property to be an antibiotic enhancer suggests FS8 as alternative or additional agent to use in conjunction with conventional antimicrobial for prevention of staphylococcal biofilm related infection. PMID:23965956

Evaluation of sampling technique and transport media for the diagnostics of adenoviral eye infections. Adenovirus sampling and transport.

PubMed

Wölfel, Roman; Pfeffer, Martin; Essbauer, Sandra; Nerkelun, Sylke; Dobler, Gerhard

2006-11-01

Human adenoviruses (HAdV) may cause pharyngoconjunctival fever, follicular conjunctivitis or epidemic keratoconjunctivitis (EKC). Especially, outbreaks of the latter may lead to severe economic losses when preventive measures are implemented too late. Thus, a safe sampling method, proper specimen transport conditions and a fast and sensitive diagnostic technique is mandatory. Two commercially available virus transport systems (VTS) were compared with two NaCl-moisturised sampling devices, one of which comprises Dacron-tipped plastic-shafted swabs and the other a cotton-tipped wood-shafted swab, available in most ophthalmologists' offices. Downstream methods for specific detection of HAdV included direct immunofluorescence assay (IFA) of conjunctival swabs, virus isolation by cell culture and quantitative real-time polymerase chain reaction (qPCR). Furthermore, the influence of application of local anaesthetics prior to swabbing on subsequent detection of HAdV was investigated. Application of local anaesthetics had a positive influence on the amount of swabbed cells, thus increasing the chance of obtaining positive results by IFA. Neither isolation of HAdV by cell culture nor by qPCR was negatively influenced by this pretreatment. Surprisingly, both commercially available VTS performed significantly worse than the NaCl-moisturised swabs. This was shown with regard to virus recovery rates in cell culture as well as viral genome copy numbers in the qPCR. Based on our results, the following recommendations are provided to improve sampling, transport and diagnostic techniques regarding conjunctival swabs for diagnosis of human adenovirus infection: (1) application of local anaesthetics, (2) NaCl-moisturised VTS for shipment of specimens, and (3) detection of HAdV by qPCR. The latter method proved to be superior to virus isolation by cell culture, including subsequent identification by IFA, because it is faster, more sensitive and allows simultaneous handling of a number of samples. Hence, countermeasures to prevent further virus spread in an outbreak situation can be implemented earlier, thus reducing the number of subsequent adenoviral infections.

Effects of Temperature during Moist Heat Treatment on Ruminal Degradability and Intestinal Digestibility of Protein and Amino Acids in Hempseed Cake.

PubMed

Karlsson, L; Ruiz-Moreno, M; Stern, M D; Martinsson, K

2012-11-01

The objective of this study was to evaluate ruminal degradability and intestinal digestibility of crude protein (CP) and amino acids (AA) in hempseed cake (HC) that were moist heat treated at different temperatures. Samples of cold-pressed HC were autoclaved for 30 min at 110, 120 or 130°C, and a sample of untreated HC was used as the control. Ruminal degradability of CP was estimated, using the in situ Dacron bag technique; intestinal CP digestibility was estimated for the 16 h in situ residue using a three-step in vitro procedure. AA content was determined for the HC samples (heat treated and untreated) of the intact feed, the 16 h in situ residue and the residue after the three-step procedure. There was a linear increase in RUP (p = 0.001) and intestinal digestibility of RUP (p = 0.003) with increasing temperature during heat treatment. The 130°C treatment increased RUP from 259 to 629 g/kg CP, while intestinal digestibility increased from 176 to 730 g/kg RUP, compared to the control. Hence, the intestinal available dietary CP increased more than eight times. Increasing temperatures during heat treatment resulted in linear decreases in ruminal degradability of total AA (p = 0.006) and individual AA (p<0.05) and an increase in intestinal digestibility that could be explained both by a linear and a quadratic model for total AA and most individual AA (p<0.05). The 130°C treatment decreased ruminal degradability of total AA from 837 to 471 g/kg, while intestinal digestibility increased from 267 to 813 g/kg of rumen undegradable AA, compared with the control. There were differences between ruminal AA degradability and between intestinal AA digestibility within all individual HC treatments (p<0.001). It is concluded that moist heat treatment at 130°C did not overprotect the CP of HC and could be used to shift the site of CP and AA digestion from the rumen to the small intestine. This may increase the value of HC as a protein supplement for ruminants.

Autoclave sterilization of instruments used on women with cervical neoplasia is an effective method of eradicating residual human papillomavirus DNA: a polymerase chain reaction-based evaluation.

PubMed

Estes, Jacob M; Kirby, Tyler O; Huh, Warner K

2007-01-01

To determine whether autoclave sterilization eradicates human papillomavirus (HPV) DNA on specula and instruments used to treat women with cervical neoplasia. Specula and instruments used in two referral colposcopy clinics were evaluated to determine the PGMY9/11 primer system's ability to amplify residual HPV DNA. Each speculum and instrument was sampled with a Dacron swab and stored in PreservCyt solution (Cytyc Corporation, Marlborough, MA) at 4 degrees C. DNA amplification was performed under standard conditions with appropriate controls followed by HPV typing using the reverse line blot test (Roche Molecular Systems, Alameda, CA). Once validated, the same polymerase chain reaction method was used on autoclave-sterilized specula and biopsy instruments and heated glass bead- and Cidex bath (Johnson & Johnson, New Brunswick, NJ)-sterilized instruments. All results, with appropriate positive and negative controls, were confirmed in triplicate. A total of 140 instruments (70 used and 70 autoclaved) were sampled for residual HPV DNA. Five samples in the contaminated specula arm were excluded from analysis secondary to insufficient sampling. Of the remaining samples, 52.3% (34/65) of contaminated instruments-both specula and biopsy instruments-had detectable HPV DNA. Fifty-five percent of contaminated biopsy instruments (11/20) were positive and 51.1% of contaminated specula (23/45) were positive. All 70 autoclaved samples (50 specula and 20 biopsy instruments) were negative for residual HPV DNA or beta-globin. One instrument in the glass bead and Cidex group that was presumed sterile was positive for HPV 16 DNA. The PGMY9/11 primer system is an effective method to detect residual HPV DNA. Autoclave sterilization appears to eradicate HPV DNA to levels undetectable with this sensitive assay, whereas heated glass beads followed by Cidex bath appears to be inadequate methods. These results suggest that autoclave sterilization is effective when using nondisposable instruments and should be the method of choice in studies using polymerase chain reaction-based amplification of HPV DNA.

Pericardial tissue valves and Gore-Tex conduits as an alternative for right ventricular outflow tract replacement in children.

PubMed

Allen, Bradley S; El-Zein, Chawki; Cuneo, Betina; Cava, Joseph P; Barth, Mary Jane; Ilbawi, Michel N

2002-09-01

There is still no perfect conduit for reconstruction of the right ventricular outflow tract (RVOT) in children. Homografts are not always available in the appropriate size, and degenerate in a few years. This study evaluates the pericardial valve with Gore-Tex conduit as an alternative for RVOT construction. From January 1, 1993, to September 30, 1999, a pericardial tissue valve was inserted in all patients undergoing RVOT reconstruction or pulmonary valve replacement (PVR) who were large enough to accommodate a tissue valve. In patients without a native main pulmonary artery, a new technique was used to construct an RV-PA conduit out of a flat sheet of Gore-Tex, as Dacron frequently leads to stenosis. Data were collected by retrospective review, follow-up echocardiograms, and assessment by a single cardiologist. There were 48 patients, 22 undergoing a PVR alone and 26 a RV-PA valved Gore-Tex conduit. Diagnosis included tetralogy of Fallot (n = 25); truncus arteriosis (n = 9); ventricular septal defect with PA (n = 5); DORV (n = 4); D-TGA with PS (n = 2); and 1 each IAA with sub AS, VSD with PI, and PS s/p Ross procedure. Patient age ranged from 3 to 33 years and 98% were reoperations. The valve sizes ranged from 19 to 33 mm and the median hospital length of stay was 4 days. There were 2 (4.2%) perioperative and 1 (2.1%) late deaths, none related to the valve or Gore-Tex conduit. At a follow-up of 15 to 86 months (mean 43 +/- 16 months), all remaining 45 patients are New York Heart Association class I, all valves are functional, and no patient has required valve or conduit replacement or revision; more importantly, echocardiogram revealed no significant valve or conduit stenosis (mean gradient 16 +/- 8 mm Hg) and no evidence of regurgitation or structural degeneration. A pericardial tissue valve and Gore-Tex conduit provides a reliable alternative for RVOT reconstruction in pediatric patients. It is readily available, molds in the limited retrosternal space, and has outstanding intermediate results with no evidence of failure or deterioration up to 7 years after insertion.

Space Station WP-2 application of LDEF MLI results

NASA Technical Reports Server (NTRS)

Smith, Charles A.; Hasegawa, Mark M.; Jones, Cherie A.

1993-01-01

The Cascaded Variable Conductance Heat Pipe Experiment, which was developed by Michael Grote of McDonnell Douglas Electronic Systems Company, was located in Tray F-9 of the Long Duration Exposure Facility (LDEF), where it received atomic oxygen almost normal to its surface. The majority of the tray was covered by aluminized Kapton polyimide multilayer insulation (MLI), which showed substantial changes from atomic oxygen erosion. Most of the outermost Kapton layer of the MLI and the polyester scrim cloth under it were lost, and there was evidence of contaminant deposition which discolored the edges of the MLI blanket. Micrometeoroid and orbital debris (MM/OD) hits caused small rips in the MLI layers, and in some cases left cloudy areas where the vapor plume caused by a hit condensed on the next layer. The MLI was bent gradually through 90 deg at the edges to enclose the experiment, and the Kapton that survived along the curved portion showed the effects of atomic oxygen erosion at oblique angles. In spite of space environment effects over the period of the LDEF mission, the MLI blanket remained functional. The results of the analysis of LDEF MLI were used in developing the standard MLI blanket for Space Station Work Package-2 (WP-2). This blanket is expected to last 30 years when exposed to the low Earth orbit (LEO) environment constituents of atomic oxygen and MM/OD, which are the most damaging to MLI materials. The WP-2 standard blanket consists of an outer cover made from Beta-cloth glass fiber fabric which is aluminized on the interior surface, and an inner cover of 0.076-mm (0.003-in) double-side-aluminized perforated Kapton. The inner reflector layers are 0.0076-mm (0.0003-in) double-side aluminized, perforated Kapton separated by layers of Dacron polyester fabric. The outer cover was selected to be resistant to the LEO environment and durable enough to survive in orbit for 30 years. This paper describes the analyses of the LDEF MLI results, and how these results contributed to the selection of the WP-2 MLI blanket materials and configuration.

Amount of Testosterone on Laundered Clothing After Use of Testosterone Topical 2% Solution by Healthy Male Volunteers.

PubMed

Satonin, Darlene K; Ni, Xiao; Mitchell, Malcolm I; Joly, Hellen; Muram, David; Small, David S

2016-02-01

Testosterone 2% solution (Axiron) applied to armpit(s) is used for replacement therapy in men with a deficiency of endogenous testosterone. To determine the amount of testosterone on subjects' T-shirts 12 hours after applying testosterone solution, the residual testosterone on subjects' T-shirts after laundering, and the testosterone transferred to unworn textile items during laundering with worn T-shirts. Healthy males ≥18 years old applied 2 × 1.5 mL of testosterone 2% solution to both axillae (total testosterone dose: 120 mg) and dressed in cotton long-sleeved T-shirts after a ≥3-minute waiting period. T-shirts were worn 12 hours before being removed and cut into halves, after which a 10 × 10 cm sample of each armpit area was excised for testosterone quantification before or after laundering with samples of unworn textiles. Testosterone on worn T-shirts before and after laundering, and on unworn textiles laundered with the worn T-shirts. Twelve subjects enrolled and completed, with only minor adverse events. Mean testosterone in unwashed worn T-shirts was 7603 μg, with high between-subject variability (3359 μg to 13,069 μg), representing 13% of the dose to 1 armpit. Mean testosterone in worn, laundered T-shirts was 260 μg (7.55 μg to 1343 μg), representing 3% of the dose to 1 armpit. Mean transferred testosterone to other textiles during laundering ranged from 69 μg on texturized Dacron 56T Double to 10,402 μg on 87/13 nylon/Lycra knit, representing 0.0382% to 5.78% of the dose to 1 armpit. Thirteen percent of the testosterone applied to axillae was transferred to T-shirts during wear. Ninety-seven percent of the transferred testosterone was removed from the T-shirts during washing, some of which was then absorbed to various degrees by other textiles. Clinical implications of these findings and biological activity of the remaining/transferred testosterone are unknown. Copyright © 2016 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

Cervical fluid interleukin 6 and intra-amniotic complications of preterm prelabor rupture of membranes.

PubMed

Musilova, Ivana; Andrys, Ctirad; Drahosova, Marcela; Soucek, Ondrej; Pliskova, Lenka; Jacobsson, Bo; Kacerovsky, Marian

2018-04-01

To determine if cervical fluid interleukin (IL)-6 concentrations in women with preterm prelabor rupture of membranes (PPROM) allows identification of microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation (IAI). One hundred forty-four women with singleton pregnancies complicated by PPROM were included in this prospective cohort study. Cervical and amniotic fluids were collected at the time of admission and concentrations of IL-6 were measured using an ELISA and point-of-care test, respectively. Cervical fluid was obtained using a Dacron polyester swab and amniotic fluid was obtained by transabdominal amniocentesis. MIAC was diagnosed based on a positive PCR result for Ureaplasma species, M. hominis, and/or C. trachomatis and/or by positivity for the 16 S rRNA gene. IAI was defined as amniotic fluid point-of-care IL-6 concentrations ≥745 pg/mL. The women were assigned to four subgroups based on the presence of MIAC and/or IAI: microbial-associated IAI (both MIAC and IAI), sterile IAI (IAI alone), MIAC alone, and without either MIAC or IAI. (1) Women with microbial-associated IAI had higher cervical fluid IL-6 concentrations (median 560 pg/mL) than did women with sterile IAI (median 303 pg/mL; p = .001), women with MIAC alone (median 135 pg/mL; p = .0004), and women without MIAC and IAI (median 180 pg/mL; p = .0001). (2) No differences were found in cervical fluid IL-6 concentrations among women with sterile IAI, with MIAC alone, and without MIAC and IAI. (3) A positive correlation was observed between cervical fluid IL-6 concentrations and the amount of Ureaplasma species in amniotic fluid (copies DNA/mL; rho = 0.57, p < .0001). (4) A weak positive correlation was detected between cervical and amniotic fluid IL-6 concentrations (rho = 0.33, p < .0001). The presence of microbial-associated IAI is associated with the highest cervical fluid IL-6 concentrations. Cervical IL-6 can be helpful in the identification of microbial-associated IAI.

[Experimental studies of original valved conduit using glutaraldehyde-preserved equine pericardium (Xenomedica)].

PubMed

Murakami, T

1989-05-01

Extracardiac conduits, such as Dacron or homo-graft, have been utilized for the operative management of many patients with congenital right ventricular outflow obstruction. However, they have been recognized to become obstructed or calcified with time. As a new material for extracardiac conduit, an original valved conduit using glutaraldehyde-preserved equine pericardium (Xenomedica) was investigated. Various types of valved conduit were evaluated for the hydrodynamics by a circulation system. A flow-pressure gradient Lissajous was used for the evaluation. The conduit of 10 mm in diameter had a high resistance to flow. The monocusp-valved conduit had a diastolic regurgitation (DR) at any given pressures and heart rates. The bicusp-valved conduit had a DR at higher heart rates (greater than 153/min). In this experiment, the tricusp-valved conduit with a valvular vertical versus horizontal length ratio of 2:3 had utmost favorable results under any given conditions. The valved conduits were also evaluated using sixteen mongrel dogs in which the conduit were used for the reconstruction of continuity between right ventricle and pulmonary artery. Five dogs died of bacterial infection or thrombotic obstruction. Following hemodynamic studies, which were performed in eleven dogs 1, 6, and 12 months after the operation, the dogs were sacrificed to evaluate the histological changes in the conduits. The valvular function had been satisfactory until one month, however, it was lost in 6 months because the valvular leaflets were covered with neointimae grown over them. Thin neointimae were observed both at the sites of anastomosis and at the base of the valves in dogs sacrificed at one month. They spread from the proximal anastomotic site to distal one. They were organized and it was hard to remove them manually. Thrombi were found in six dogs at the proximal anastomotic site with intimal hyperplasia. There was no calcification in Xenomedica and its degenerative change was minimal. In conclusion, the equine pericardium valved conduit is thought to be an useful material for the reconstruction of right ventricular outflow obstruction to improve early hemodynamic changes after operation.

Mechanical support of total cavopulmonary connection with an axial flow pump.

PubMed

Riemer, R Kirk; Amir, Gabriel; Reichenbach, Steven H; Reinhartz, Olaf

2005-08-01

Even under optimal circumstances, total cavopulmonary connection is associated with a continuous late risk of death. Hemodynamics are distinctly abnormal, with increased systemic venous pressures and frequent low cardiac output. Our study uses a sheep model of total cavopulmonary connection to test the response to axial flow pump (Thoratec HeartMate II; Thoratec Corporation (Pleasanton, Calif)) support of total cavopulmonary connection, which might be suitable to treat patients with failing Fontan circulation. Eight sheep (42-48 kg) were studied. After pilot studies in 3 animals, 5 underwent both pump-supported and nonsupported total cavopulmonary connection in alternating sequence for up to 2 hours. This was achieved with a 12-mm polytetrafluoroethylene graft from the (distally ligated) superior vena cava to the main pulmonary artery and a cannula placed in the inferior vena cava with an attached 16-mm Dacron graft to the main pulmonary artery. Pressures (arterial, inferior vena cava, left atrium, and pulmonary artery) and flows (ascending aorta and inferior vena cava) were recorded over 1 hour both with unsupported total cavopulmonary connection and after placing an axial flow pump (Thoratec HeartMate II) between the inferior vena caval inflow cannula and the main pulmonary artery. Under nonsupported total cavopulmonary connection circulation, inferior vena caval and aortic blood flow decreased by nearly 50%. Inferior vena caval pressure nearly doubled, whereas arterial pressure decreased by one third. Pulmonary artery pressure became nonpulsatile; however, mean pulmonary artery pressure and left atrial pressure did not change significantly. With pump-supported Fontan circulation, cardiac output, inferior vena caval flow, and arterial pressure returned to baseline. Inferior vena caval pressure decreased to below baseline levels. Mean pulmonary artery pressure and left atrial pressure again remained unchanged. Axial flow pump support from the inferior vena cava to the pulmonary artery can prevent the substantial decrease of aortic flow and pressure associated with total cavopulmonary connection and can reverse its poor hemodynamics. This is a simple model that can be used to further evaluate the potential of mechanical support as a treatment option in failing Fontan circulation.

Effects of condensed tannins in wrapped silage bales of sainfoin (Onobrychis viciifolia) on in vivo and in situ digestion in sheep.

PubMed

Theodoridou, K; Aufrère, J; Andueza, D; Le Morvan, A; Picard, F; Pourrat, J; Baumont, R

2012-02-01

The objective of this study was to characterize the condensed tannins (CTs) in wrapped silage bales of sainfoin (Onobrychis viciifolia) and examine their potential action on in vivo and in situ digestive characteristics in sheep. Silage was made from sainfoin, cut at two phenological stages. The first phenological stage, at which silage was made, was from the first vegetation cycle at the end of flowering and the second stage silage was made from regrowth, 5 weeks after the first cut, but before flowering. The silages made from the two phenological stages were fed to 12 rumen-fistulated sheep in a crossover design. Of the 12 sheep, six received polyethylene glycol (PEG) to bind with and remove the effects of CT, whereas the other six were dosed with water. Organic matter digestibility, total-tract N digestibility and N (N) balance were measured over 6 days. Kinetic studies were performed on total N, ammonia N (NH3-N) and volatile fatty acids (VFAs) in rumen fluid before and 1.5, 3 and 6 h after feeding. The kinetics of degradation of dry matter and N from Dacron bags suspended in the rumen were also determined. Biological activity of CT (protein-binding capacity) and CT concentration were greater for the silage made from sainfoin at the early flowering stage. Total-tract N digestibility was increased by the addition of PEG (P < 0.001) to the sainfoin silage before flowering (P < 0.001). CTs decreased N excretion in urine (P < 0.05) and increased faecal N excretion (P < 0.001), but had no effect on body N retention, which is beneficial for the animal. Ruminal N degradability was smaller in the presence of active CT (P < 0.001) at both phenological stages; however, soluble N (P = 0.2060) and NH3-N (P = 0.5225) concentrations in rumen fluid remained unchanged. The results of this experiment indicate that CT in the sainfoin retain their ability to affect the nutritive value of preserved forage legumes.

Effects of Temperature during Moist Heat Treatment on Ruminal Degradability and Intestinal Digestibility of Protein and Amino Acids in Hempseed Cake

PubMed Central

Karlsson, L.; Ruiz-Moreno, M.; Stern, M. D.; Martinsson, K.

2012-01-01

The objective of this study was to evaluate ruminal degradability and intestinal digestibility of crude protein (CP) and amino acids (AA) in hempseed cake (HC) that were moist heat treated at different temperatures. Samples of cold-pressed HC were autoclaved for 30 min at 110, 120 or 130°C, and a sample of untreated HC was used as the control. Ruminal degradability of CP was estimated, using the in situ Dacron bag technique; intestinal CP digestibility was estimated for the 16 h in situ residue using a three-step in vitro procedure. AA content was determined for the HC samples (heat treated and untreated) of the intact feed, the 16 h in situ residue and the residue after the three-step procedure. There was a linear increase in RUP (p = 0.001) and intestinal digestibility of RUP (p = 0.003) with increasing temperature during heat treatment. The 130°C treatment increased RUP from 259 to 629 g/kg CP, while intestinal digestibility increased from 176 to 730 g/kg RUP, compared to the control. Hence, the intestinal available dietary CP increased more than eight times. Increasing temperatures during heat treatment resulted in linear decreases in ruminal degradability of total AA (p = 0.006) and individual AA (p<0.05) and an increase in intestinal digestibility that could be explained both by a linear and a quadratic model for total AA and most individual AA (p<0.05). The 130°C treatment decreased ruminal degradability of total AA from 837 to 471 g/kg, while intestinal digestibility increased from 267 to 813 g/kg of rumen undegradable AA, compared with the control. There were differences between ruminal AA degradability and between intestinal AA digestibility within all individual HC treatments (p<0.001). It is concluded that moist heat treatment at 130°C did not overprotect the CP of HC and could be used to shift the site of CP and AA digestion from the rumen to the small intestine. This may increase the value of HC as a protein supplement for ruminants. PMID:25049517

M2-F1 lifting body and Paresev 1B on ramp

NASA Technical Reports Server (NTRS)

1963-01-01

In this photo of the M2-F1 lifting body and the Paresev 1B on the ramp, the viewer sees two vehicles representing different approaches to building a research craft to simulate a spacecraft able to land on the ground instead of splashing down in the ocean as the Mercury capsules did. The M2-F1 was a lifting body, a shape able to re-enter from orbit and land. The Paresev (Paraglider Research Vehicle) used a Rogallo wing that could be (but never was) used to replace a conventional parachute for landing a capsule-type spacecraft, allowing it to make a controlled landing on the ground. The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey acquired a Pontiac Catalina convertible with the largest engine available. He took the car to Bill Straup's renowned hot-rod shop near Long Beach for modification. With a special gearbox and racing slicks, the Pontiac could tow the 1,000-pound M2-F1 110 miles per hour in 30 seconds. It proved adequate for the roughly 400 car tows that got the M2-F1 airborne to prove it could fly safely and to train pilots before they were towed behind a C-47 aircraft and released. These initial car-tow tests produced enough flight data about the M2-F1 to proceed with flights behind the C-47 tow plane at greater altitudes. The C-47 took the craft to an altitude of 12,000 where free flights back to Rogers Dry Lake began. Pilot for the first series of flights of the M2-F1 was NASA research pilot Milt Thompson. Typical glide flights with the M2-F1 lasted about two minutes and reached speeds of 110 to l20 mph. A small solid landing rocket, referred to as the 'instant L/D rocket,' was installed in the rear base of the M2-F1. This rocket, which could be ignited by the pilot, provided about 250 pounds of thrust for about 10 seconds. The rocket could be used to extend the flight time near landing if needed. More than 400 ground tows and 77 aircraft tow flights were carried out with the M2-F1. The success of Dryden's M2-F1 program led to NASA's development and construction of two heavyweight lifting bodies based on studies at NASA's Ames and Langley research centers--the M2-F2 and the HL-10, both built by the Northrop Corporation, and the U.S. Air Force's X-24 program, with an X-24A and -B built by Martin. The Lifting Body program also heavily influenced the Space Shuttle program. The M2-F1 program demonstrated the feasibility of the lifting body concept for horizontal landings of atmospheric entry vehicles. It also demonstrated a procurement and management concept for prototype flight test vehicles that produced rapid results at very low cost (approximately $50,000, excluding salaries of government employees assigned to the project). The Paresev (Paraglider Rescue Vehicle) was an indirect outgrowth of kite-parachute studies by NACA Langley engineer Francis M. Rogallo. In the early 1960s the 'Rogallo wing' seemed an excellent means of returning a spacecraft to Earth. The delta wing design was patented by Mr. Rogallo. In May 1961, Robert R. Gilruth, director NASA's Space Task Group, requested studies of an inflatable Rogallo-type 'Parawing' for spacecraft. Several companies responded; North American Aviation produced the most acceptable concept and development was contracted to that company. In November 1961 NASA Headquarters launched a paraglider development program, with Langely doing wind-tunnel studies and the NASA Flight Research Center supporting the North American test program. The North American concept was a capsule type vehicle with a stowed 'parawing' that could be deployed and controlled from within for a landing more like an airplane instead of a 'splash down' in the ocean as was the practice in the Mercury and later the Gemini and Apollo programs. The logistics became enormous and the price exorbitant, besides which, NASA pilots and engineers felt some baseline experience like building a vehicle and flying a Parawing should be accomplished first. The Paresev (Paraglider Research Vehicle) was used to gain in-flight experience with four different membranes (wings) and was not used to develop the more complicated inflatable deployment system. The Paresev was designed by Charles Richard, of the Flight Research Center's Vehicle and System Dynamics Branch, with the rest of the team being: engineers Richard Klein, Gary Layton, John Orahood, and Joe Wilson; Frank Fedor and LeRoy Barto from the Maintenance and Manufacturing Branch; Project Manager Victor Horton, with Gary Layton becoming Project Manager later on in the Program. Mr. Paul Bikle, Director of the Center, gave instructions that were short and to the point: build a single-seat Paraglider and 'do it quick and cheap.' The Paresev was unpowered, the 'fuselage' an open framework fabricated of welded 4130 steel tubing referred to as a `space frame.' The keel and leading edges of the wings were constructed of 2 1/2-inch diameter aluminum tubing. The leading edge sweep angle was held constant at 50 degrees by a rigid spreader bar. Additional wing structure fabricated of steel tubing ensured structural integrity. Seven weeks after the project was initiated the team rolled out the Paresev 1. It resembled a grown-up tricycle, with a rudimentary seat, an angled tripod mast, and, perched on top of the mast, a Rogallo-type parawing. The pilot sat out in the open, strapped in the seat, with no enclosure of any kind. He controlled the descent rate by tilting the wing fore and aft, and turned by tilting the wing from side to side with a control stick that came from overhead. NASA registered the Paresev, the first NASA research airplane to be constructed totally 'in-house,' with the Federal Aviation Administration on February 12, 1962. Flight testing started immediately. There was one space frame built called the Paresev that used four different wing types. Paresev 1 had a linen membrane, with the control stick coming from overhead in front of the pilots seat. Paresev 1A had a regulation control stick and a Dacron membrane. Paresev 1B had a smaller Dacron membrane with the space frame remaining the same. Paresev 1C used a half-scale version of the inflatable Gemini parawing with a small change to the space frame. All `space frames,' regardless of the parawing configuration, had a shield with 'Paresev 1-A' and the NASA meatball on the front of the vehicle. PARESEV-1 After the space frame was completed a sailmaker was asked to sew the wing membrane according to the planform developed by NASA Flight Research Center personnel. He suggested using Dacron instead of the linen fabric chosen, but yielded to the engineers' specs. A nylon bolt rope was attached in the trailing edge of the 150-square-foot wing membrane. The rope was unrestrained except at the wing tips and was therefore free to equalize the load between the two lobes of the wing. This worked reasonably well, but flight tests proved the wing to be too flexible with it flapping and bulging in alarming ways. The poor membrane design led to trailing edge flutter, with longitudinal and lateral stick forces being severe. A number of different rigging modifications to improve the flying characteristics were tried, but very few were successful and none were predictable. Everything seemed to affect stick forces in the worst way. The fifth flight aloft lasted 10 seconds. On a ground tow the Paresev and pilot fell 10 feet. Considerable damage was done to the Paresev with the pilot, Bruce Peterson, being taken to the base hospital. Injuries sustained by the pilot were not serious. After this accident the Paresev was extensively rebuilt and renamed, Paresev-1A. PARESEV 1-A The sailmaker was asked again to construct a 150-square-foot membrane the way he wanted to. The resulting wing membrane had excellent contours in flight and was made from 6 ounce Dacron. The space frame was rebuilt with more sophistication than the Paresev 1 had. The shock absorbers were Ford automotive parts, the wing universal joint was a 1948 Pontiac part, and the tires and wheels were from a Cessna 175 aircraft. The overhead stick was replaced with a stick and pulley arrangement that operated more like conventional aircraft controls. This vehicle had much improved stick forces and handling qualities. The instrumentation used to obtain data was quite crude, partially as a result of the desire to keep the program simple and low in cost and also because there was no onboard power. To measure performance, technicians installed a large alpha vane on the wing apex with a scale at the trailing edge that the pilot could read directly. A curved bubble level measured the vehicle's attitude, and a Fairchild camera recorded the glide slope PARESEV 1-B The Paresev 1-B used the Paresev 1-A space frame with a smaller Dacron wing (100 square feet) and was flight tested to evaluate its handling qualities with lower lift-to-drag values. One NASA project engineer described its gliding ability as 'pretty scary.' PARESEV 1-C The space frame of the vehicle remained almost unchanged from the earlier vehicles. However, a new control box gave the pilot the ability to increase or decrease the nitrogen in the inflatable wing supports to compensate for the changing density of the air. Two bottles of nitrogen provided an extra supply of nitrogen. The vehicle featured a partially inflatable wing. The whole wing was not inflatable; the three chambers that acted as spars and supported the wing inflated. The center spar ran fore and aft and measured 191 inches; two other inflatable spars formed the leading edges. These three compartments were filled with nitrogen under pressure to make them rigid. The Paresev in this configuration was expected to closely approximate the aerodynamic characteristics that would be encountered with the Gemini space capsule with a parawing extended. The Paresev was very unstable in flight with this configuration. The first Paresev flights began with tows across the dry lakebed, in 1962, using a NASA vehicle, an International Harvester carry-all (6 cylinder). Eventually ground and airtows were done using a Stearman sport biplane (450 hp), a Piper Super Cub (150-180 hp), Cessna L-19 (200 hp Bird Dog) and a Boeing-Vertol HC-1A. Speed range of the Paresev was about 35-65 mph. The Paresev completed nearly 350 flights during a research program from 1962 until 1964. Pilots flying the Paresev included NASA pilots Milton Thompson, Bruce Peterson, and Neil Armstrong from Dryden, Robert Champine from Langley, and astronaut Gus Grissom, plus North American test pilot Charles Hetzel. The Paresev was legally transferred to the National Air and Space Museum of the Smithsonian Institute, Washington, D.C. Despite its looks, the Paresev was a useful research aircraft that helped develop a new way to fly. Although the Rogallo wing was never used on a spacecraft, it revolutionized the sport of hang gliding, and a different but related kind of wing will be used on the X-38 technology demonstrator for a crew return vehicle from the International space station.

Mitigation of EMU Glove Cut Hazard by MMOD Impact Craters on Exposed ISS Handrails

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Ryan, Shannon

2009-01-01

Recent cut damages to crewmember extravehicular mobility unit (EMU) gloves during extravehicular activity (EVA) onboard the International Space Station (ISS) has been found to result from contact with sharp edges or pinch points rather than general wear or abrasion. One possible source of cut-hazards are protruding sharp edged crater lips from impact of micrometeoroid and orbital debris (MMOD) particles on external metallic handrails along EVA translation paths. During impact of MMOD particles at hypervelocity an evacuation flow develops behind the shock wave, resulting in the formation of crater lips that can protrude above the target surface. In this study, two methods were evaluated to limit EMU glove cut-hazards due to MMOD impact craters. In the first phase, four flexible overwrap configurations are evaluated: a felt-reusable surface insulation (FRSI), polyurethane polyether foam with beta-cloth cover, double-layer polyurethane polyether foam with beta-cloth cover, and multi-layer beta-cloth with intermediate Dacron netting spacers. These overwraps are suitable for retrofitting ground equipment that has yet to be flown, and are not intended to protect the handrail from impact of MMOD particles, rather to act as a spacer between hazardous impact profiles and crewmember gloves. At the impact conditions considered, all four overwrap configurations evaluated were effective in limiting contact between EMU gloves and impact crater profiles. The multi-layer beta-cloth configuration was the most effective in reducing the height of potentially hazardous profiles in handrail-representative targets. In the second phase of the study, four material alternatives to current aluminum and stainless steel alloys were evaluated: a metal matrix composite, carbon fiber reinforced plastic (CFRP), fiberglass, and a fiber metal laminate. Alternative material handrails are intended to prevent the formation of hazardous damage profiles during MMOD impact and are suitable for flight hardware yet to be constructed. Of the four materials evaluated, only the fiberglass formed a less hazardous damage profile than the baseline metallic target. Although the CFRP laminate did not form any noticeable crater lip, brittle protruding fibers are considered a puncture risk. In parallel with EMU glove redesign efforts, modifications to metallic ISS handrails such as those evaluated in this study provide the means to significantly reduce cut-hazards from MMOD impact craters.

Hemocompatibility studies on a degradable polar hydrophobic ionic polyurethane (D-PHI).

PubMed

Brockman, Kathryne S; Kizhakkedathu, Jayachandran N; Santerre, J Paul

2017-01-15

Biomaterial blood compatibility is a complex process that involves four key pathways, including the coagulation cascade, the complement system, platelets, and leukocytes. While many studies have addressed the initial contact of blood with homopolymeric (e.g. Teflon) or simple copolymeric (e.g. Dacron) biomaterials, relatively less attention has been given to investigating blood coagulation with respect to complex copolymeric systems containing well defined and diverse function. The current study sought to assess the hemocompatibility of a complex polyurethane (PU) containing a unique combination of polar, hydrophobic, and ionic domains (D-PHI). This included a whole blood (WB) study, followed by tests on the intrinsic and extrinsic coagulation pathways, complement activation, platelet activation, and an assessment of the effect of leukocytes on platelet-biomaterial interactions. A small increase in blood clot formation was observed on D-PHI in WB; however, there was no significant increase in clotting via the intrinsic coagulation cascade. No significant increase in platelet adhesion and only a very slight increase in platelet activation were observed in comparison to albumin-coated substrates (negative control). D-PHI showed mild complement activation and increased initiation of the extrinsic pathway of coagulation, along with the observation that leukocytes were important in mediating platelet-biomaterial interactions. It is proposed that complement is responsible for activating coagulation by inciting leukocytes to generate tissue factor (TF), which causes extrinsic pathway activation. This low level of blood clotting on D-PHI's surface may be necessary for the beneficial wound healing of vascular constructs that has been previously reported for this material. Understanding the hemocompatibility of devices intended for blood-contacting applications is important for predicting device failure. Hemocompatibility is a complex parameter (affected by at least four different mechanisms) that measures the level of thrombus generation and immune system activation resulting from blood-biomaterial contact. The complexity of hemocompatibility implies that homopolymers are unlikely to solve the clotting challenges that face most biomaterials. Diversity in surface chemistry (containing hydrophobic, ionic, and polar domains) obtained from engineered polyurethanes can lead to favourable interactions with blood. The current research considered the effect of a highly functionalized polyurethane biomaterial on all four mechanisms in order to provide a comprehensive in vitro measure of the hemocompatibility of this unique material and the important mechanisms at play. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Aerogel-Based Multilayer Insulation with Micrometeoroid Protection

NASA Technical Reports Server (NTRS)

Begag, Redouane; White, Shannon

2013-01-01

Ultra-low-density, highly hydrophobic, fiber-reinforced aerogel material integrated with MLI (aluminized Mylar reflectors and B4A Dacron separators) offers a highly effective insulation package by providing unsurpassed thermal performance and significant robustness, delivering substantial MMOD protection via the addition of a novel, durable, external aerogel layer. The hydrophobic nature of the aerogel is an important property for maintaining thermal performance if the material is exposed to the environment (i.e. rain, snow, etc.) during ground installations. The hybrid aerogel/MLI/MMOD solution affords an attractive alternative because it will perform thermally in the same range as MLI at all vacuum levels (including high vacuum), and offers significant protection from micrometeoroid damage. During this effort, the required low-density and resilient aerogel materials have been developed that are needed to optimize the thermal performance for space (high vacuum) cryotank applications. The proposed insulation/MMOD package is composed of two sections: a stack of interleaved aerogel layers and MLI intended for cryotank thermal insulation, and a 1.5- to 1-in. (.2.5- to 3.8- cm) thick aerogel layer (on top of the insulation portion) for MMOD protection. Learning that low-density aerogel cannot withstand the hypervelocity impact test conditions, the innovators decided during the course of the program to fabricate a high-density and strong material based on a cross-linked aerogel (X-aerogel; developed elsewhere by the innovators) for MMOD protection. This system has shown a very high compressive strength that is capable of withstanding high-impact tests if a proper configuration of the MMOD aerogel layer is used. It was learned that by stacking two X-aerogel layers [1.5-in. (.3.8-cm) thick] separated by an air gap, the system would be able to hold the threat at a speed of 5 km/s and gpass h the test. The first aerogel panel stopped the projectile from damaging the second aerogel panel. The impacted X-aerogel (the back specimen from the successful test) was further tested in comparison to another similar sample (not impacted) at Kennedy Space Center for thermal conductivity evaluation at cryogenic conditions. The specimens were tested under high vacuum and cryogenic temperatures, using Cryostat 500. The results show that the specimen did not lose a significant amount of thermal performance due to the impact test, especially at high vacuum.

[Laboratory diagnosis of genital herpes--direct immunofluorescence method].

PubMed

Majewska, Anna; Romejko-Wolniewicz, Ewa; Zareba-Szczudlik, Julia; Kilijańczyk, Marek; Gajewska, Małgorzata; Młynarczyk, Grazyna

2013-07-01

Aim of the study was to determine clinical usefulness of direct immunofluorescence method in the laboratory diagnosis of genital herpes in women. Overall 187 anogenital swabs were collected from 120 women. Using a dacron-tipped applicator 83 swabs were collected from women suspected of genital herpes and 104 from patients with no signs of genital infection. All samples were tested using cell culture (Vero cell line) and then direct immunofluorescence method (DIF) for the identification of antigens of herpes simplex viruses: HSV-1 and HSV-2. Characteristic cytopathic effect (CPE), indicative of alphaherpesvirus infection, was observed in 43.4% of cultures with clinical specimens collected from women with suspected genital herpes and in 29.8% of cultures of clinical specimens taken from patients with no clinical symptoms of genital herpes. Herpes simplex viruses were determined in 73 samples by direct immunofluorescence method after amplification of the virus in cell culture. The DIF test confirmed the diagnosis based on the microscopic CPE observation in 85%. In 15% of samples (taken from pregnant women without clinical signs of infection) we reported positive immunofluorescence in the absence of CPE. The frequency of antigen detection was statistically significantly higher in samples that were positive by culture study (chi-square test with Yates's correction, p < 0.01). This method proved to be highly sensitive (97%) in women with clinically suspected infection. High negative predictive value (99%) proves the clinical utility of the DIF in these group of patients. In asymptomatic infections, viral antigens were detected most frequently in the swabs from the cervical canal, and in cases of suspected genital herpes in swabs taken from the vestibule of the vagina and the vulva. However, there was no statistically significant difference in the frequency of detection of Herpes Simplex Virus antigens in specimens from different parts of the genital tract in both groups of women (chi-square test, p > 0.05). In our study HHV-1 was the main causative agent of genital herpes. The growing worldwide prevalence of genital herpes, challenges with the clinical diagnosis, and availability of effective antiviral therapy are the main reasons for a growing interest in rapid, proper laboratory diagnosis of infected patients. Optimal testing diagnostic algorithm depends on patient population, clinical circumstances and availability. Our results indicated that combination of laboratory tests may help to establish the diagnosis if genital herpes is suspected but there are no typical signs.

Surgical infrarenal "neo-neck" technique during elective conversion after EVAR with suprarenal fixation.

PubMed

Bonvini, S; Wassermann, V; Menegolo, M; Scrivere, P; Grego, F; Piazza, M

2015-08-01

Conversion of a previous endovascular aneurysm repair (EVAR) with suprarenal fixation is a challenging situation even in the elective setting. The outcomes of a technique based on preservation of the first proximal covered stent of the endograft, used as a "neo-neck" for proximal anastomosis, are presented. From 2001 to 2014, nine patients underwent elective conversion of a previous suprarenally fixed EVAR. After supraceliac clamping, the aneurysm sac was opened and the endograft identified; the fabric was cut beyond the first covered stent together with its native aortic wall in order to create a "neo-neck." An aortic balloon was inflated into the visceral aorta to avoid back bleeding. A Dacron bifurcated tube graft (Intergard, Maquet) was then sutured to the neo-neck mimicking endobanding, passing the stitches into the aortic wall and the first covered stent. The mean age was 68 years (range, 52-84 years). The stent grafts removed were four Zenith (Cook Medical), three Endurant (Medtronic), and two E-vita (Jotec). The indication for conversion was type 1A (n = 2), type 2 (n = 2), and type 3 (n = 1) endoleak, complete endograft thrombosis (n = 2), and abdominal pain with sac enlargement with no radiological sign of endoleak (n = 2). Blood loss was 1,428 mL (range 500-3,000 mL); the visceral ischemic time to perform the proximal anastomosis was 23.5 min ± 2.3 min). The post-operative complication rate was 11% (n = 1/9) related to a case of sac wall bleeding requiring re-intervention; mortality at 30 days was 0%. At 22 months (range, 8-41) the computed tomography angiogram demonstrated no signs of leaks or anastomotic pseudoaneurysm. Preservation of the proximal covered stent of an endograft with suprarenal fixation used as an infrarenal "neo-neck" with incorporation of the aorta to the suture line during elective surgical explantation simplifies the procedure, and can be achieved with very low early morbidity and mortality; furthermore, it seems to be durable over mid-term follow up. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Large Scale Testing of a Foam/Multilayer Insulation Thermal Control System (TCS) for Cryogenic Upper Stages

NASA Technical Reports Server (NTRS)

Hastings, Leon; Martin, James

1998-01-01

The development of high energy cryogenic upper stages is essential for the efficient delivery of large payloads to various destinations envisioned in future programs. A key element in such upper stages is cryogenic fluid management (CFM) advanced development/technology. Due to the cost of and limited opportunities for orbital experiments, ground testing must be employed to the fullest extent possible. Therefore, a system level test bed termed the Multipurpose Hydrogen Test Bed (MHTB), which is representative in size and shape (3 meter diameter by 3 meter long with a volume of 18 cubic meters) of a fully integrated space transportation vehicle liquid hydrogen propellant tank has been established. To date, upper stage studies have often baselined the foam/multilayer insulation (FMLI) combination concept; however, hardware experience with the concept is minimal and was therefore selected for the MHTB. The foam element (isofoam SS-1 171 with an average thickness of 3.5 centimeters) is designed to protect against ground hold/ascent flight environments, and allows for the use of a dry nitrogen purge as opposed to the more complex/heavy helium purge subsystem normally required with MLI in cryogenic applications. The MLI (45 layers of Double Aluminized Mylar with Dacron spacers) provides protection in the vacuum environment of space and is designed for an on-orbit storage period of 45 days. Several unique features were incorporated in the MLI concept and included: variable density MLI (reduces weight and radiation losses by changing the layer density), larger but fewer DAM perforations for venting during ascent to orbit (reduces radiation losses), and roll wrap installation of the MLI with a commercially established process to lower assembly man-hours and reduce seam heat leak. Thermal performance testing of the MHTB TCS was conducted during three test series conducted between September 1995 and May 1996. Results for the ground hold portion of the tests were as expected producing an average heat leak of 63 WattS/M2 at an average foam surface temperature of 170 K. The results of the simulated orbit hold test interval produced heat leaks ranging from 0.085 to 0.22 Watts/squareM at warm boundary temperatures of 164K and 305K, respectively. When compared to the performance for a traditional MLI system, a 60% reduction in orbital heat leak or boiloff was measured. Overall, the MHTB TCS demonstrated satisfactory performance for all mission phases required of a cryogenic upper stage.

Comparative Analysis of the Biaxial Mechanical Behavior of Carotid Wall Tissue and Biological and Synthetic Materials Used for Carotid Patch Angioplasty

PubMed Central

Kamenskiy, Alexey V.; Pipinos, Iraklis I.; MacTaggart, Jason N.; Jaffar Kazmi, Syed A.; Dzenis, Yuris A.

2011-01-01

Patch angioplasty is the most common technique used for the performance of carotid endarterectomy. A large number of patching materials are available for use while new materials are being continuously developed. Surprisingly little is known about the mechanical properties of these materials and how these properties compare with those of the carotid artery wall. Mismatch of the mechanical properties can produce mechanical and hemodynamic effects that may compromise the long-term patency of the endarterectomized arterial segment. The aim of this paper was to systematically evaluate and compare the biaxial mechanical behavior of the most commonly used patching materials. We compared PTFE (n = 1), Dacron (n = 2), bovine pericardium (n = 10), autogenous greater saphenous vein (n = 10), and autogenous external jugular vein (n = 9) with the wall of the common carotid artery (n = 18). All patching materials were found to be significantly stiffer than the carotid wall in both the longitudinal and circumferential directions. Synthetic patches demonstrated the most mismatch in stiffness values and vein patches the least mismatch in stiffness values compared to those of the native carotid artery. All biological materials, including the carotid artery, demonstrated substantial nonlinearity, anisotropy, and variability; however, the behavior of biological and biologically-derived patches was both qualitatively and quantitatively different from the behavior of the carotid wall. The majority of carotid arteries tested were stiffer in the circumferential direction, while the opposite anisotropy was observed for all types of vein patches and bovine pericardium. The rates of increase in the nonlinear stiffness over the physiological stress range were also different for the carotid and patching materials. Several carotid wall samples exhibited reverse anisotropy compared to the average behavior of the carotid tissue. A similar characteristic was observed for two of 19 vein patches. The obtained results quantify, for the first time, significant mechanical dissimilarity of the currently available patching materials and the carotid artery. The results can be used as guidance for designing more efficient patches with mechanical properties resembling those of the carotid wall. The presented systematic comparative mechanical analysis of the existing patching materials provides valuable information for patch selection in the daily practice of carotid surgery and can be used in future clinical studies comparing the efficacy of different patches in the performance of carotid endarterectomy. PMID:22168740

Alkaptonuric aortic stenosis: a case report.

PubMed

Gonzales, M E

1999-04-01

Alkaptonuria is a rare disease of phenylalanine, aromatic amino acids, and tyrosine metabolism. Because of a genetic deficiency of the enzyme homogentisic acid oxidase, an accumulation of homogentisic acid causes ochronotic pigment deposition. The most common clinical manifestations are arthropathy, urinary calculi and discoloration, cutaneous and cartilaginous pigmentation, and cardiac valvular disease. Arthropathy and aortic stenosis are the most debilitating manifestations of the disease. A case of alkaptonuric aortic stenosis is described. A 75-year-old woman with a history of alkaptonuria presented in the emergency department with complaints of progressive dyspnea. Upon examination, the patient was hypertensive, tachypneic, and tachycardic with premature ventricular contractions. She had pitting edema of the lower extremities and complaints of generalized weakness. Chest x-rays revealed congestive heart failure and pulmonary edema. Diuretics were administered, and a continuous nitroglycerin infusion was initiated in the emergency department. The patient was admitted for further evaluation. The patient's respiratory status continued to decline. She was intubated endotracheally 1 day after admission. Subsequent cardiac evaluation revealed an ejection fraction of 35%, severe aortic stenosis, mild coronary artery disease, ischemic cardiomyopathy, and anteroapical akinesis. A dobutamine infusion was instituted for persistent hypotension, and renal dose dopamine was initiated for oliguric renal failure. The patient underwent an emergency operation for an aortic valve replacement with a Dacron patch 10 days after admission. Cardiopulmonary bypass and mild hypothermia were used during the procedure. The patient's hemodynamic status remained tenuous throughout the procedure. Although the first attempt to wean off cardiopulmonary bypass failed, the second attempt was successful with the aid of an intra-aortic balloon pump, inotropic support, and atrioventricular pacing. These measures were maintained during transport to the surgical intensive care unit. In the intensive care unit, the patient did not have an audible blood pressure or a palpable pulse without the support of the intra-aortic balloon pump and atrioventricular pacing. Coarse atrial fibrillation was the underlying electrocardiogram rhythm in the absence of atrioventricular pacing. Sodium bicarbonate was given without improvement. After discussion with the family, all life support measures were discontinued. The patient died 10 minutes after her arrival in the intensive care unit. Alkaptonuria's pathogenesis is manifested as both local and systemic in nature. Collagen vascular diseases share a similar pattern of multisystem involvement. Despite the negative outcome for the patient described, valuable insight can be obtained by studying this case and noting the anesthetic considerations specific to collagen vascular diseases in general.

A multicenter experience with the surgical treatment of infected abdominal aortic endografts.

PubMed

Davila, Victor J; Stone, William; Duncan, Audra A; Wood, Emily; Jordan, William D; Zea, Nicholas; Sternbergh, W Charles; Money, Samuel R

2015-10-01

Single-center experiences with the treatment of infected endografts after endovascular aortic repair (I-EVAR) have been reported. We performed a multicenter review of the surgical care of these patients to elucidate short-term and long-term outcomes. A retrospective analysis of all EVAR explants from 1997 to 2014 at four institutions was performed. Patients with I-EVAR undergoing surgical treatment were reviewed. Data were obtained detailing preoperative demographics, and postoperative morbidity and mortality. Thirty-six patients (30 male) were treated with endovascular graft excision and revascularization for I-EVAR with a median age of 69 years (range, 54-80 years). Average time from the initial EVAR to presentation was 589 days (range, 43-2466 days). Preoperative comorbidities included hypertension, 32 (89%); tobacco use, 31(86%); coronary artery disease, 26 (72%); hyperlipidemia, 25 (69%), peripheral artery disease, 13 (36%); cerebrovascular disease, 10 (28%); diabetes, 10 (28%); chronic obstructive pulmonary disease, 9 (25%); and chronic kidney disease, 9 (25%). The most common presenting patient characteristics were leukocytosis, 23 (63%); pain, 21 (58%); and fever, 20 (56%), which were present an average of 65 days (range, 0-514 days) before explantation. Nine different types of endograft were removed. Three patients (8%) underwent emergency explantation. Thirty-four patients (89%) underwent total graft excision, and two patients (6%) underwent partial excision. Methods of reconstruction were in situ in 27 (75%) and extra-anatomic in nine (28%). Conduits used were Dacron (DuPont, Wilmington, Del), with or without rifampin, polytetrafluoroethylene, cryopreserved allograft, and femoral vein. Forty-nine organisms grew from operative cultures. Gram-positive organisms were the most common, found in 24 (67%), including Staphylococcus in 13 (36%) and Streptococcus in six (17%). Anaerobes were cultured in 6 patients (17%), gram-negative organisms in 6 (17%), and fungus in 5 (14%). Thirty-one patients (86%) received long-term antibiotics. Early complications included acute renal failure requiring dialysis, 12 (33%); respiratory failure, 3 (8%); bleeding, 4 (11%); and sepsis, 2 (6%). Six patients required re-exploration due to hematoma, infected hematoma, lymphatic leak, bowel perforation, open abdomen at initial operation, and anastomotic bleeding. Perioperative mortality was 8% (3 of 36), and long-term mortality was 25% (9 of 36) at a mean follow-up of 569 days (range, 0-3079 days). Type of reconstruction (in situ vs extra-anatomic) or conduit type did not affect perioperative or overall mortality. I-EVAR is a rare but potentially devastating clinical problem. Although perioperative mortality is acceptable, long-term mortality is high. The most common postoperative complication was acute renal failure requiring dialysis. Although this is the largest series of I-EVAR, further studies are needed to understand the risk factors and preventive measures. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

A Prospective, Randomized, Multicenter Clinical Trial on the Safety and Efficacy of a Ready-to-Use Fibrin Sealant as an Adjunct to Hemostasis during Vascular Surgery.

PubMed

Chetter, Ian; Stansby, Gerard; Sarralde, José Aurelio; Riambau, Vicente; Giménez-Gaibar, Antonio; MacKenzie, Kent; Acín, Francisco; Navarro-Puerto, Jordi

2017-11-01

Anastomotic or "stitch hole" bleeding is common during vascular surgery with synthetic material such as Dacron or polytetrafluoroethylene. Hemostatic adjuncts such as fibrin sealant (FS) may reduce blood loss and operating time in such circumstances. We evaluated the safety and the hemostatic effectiveness of a ready-to-use human plasma-derived FS in vascular surgery. Patients with mild/moderate suture line bleeding during elective, open, vascular surgery using synthetic grafts or patches were studied. In an initial Exploratory Study, all patients were treated with FS Grifols, and in a subsequent Primary Study were randomized in a 2:1 ratio to FS Grifols or manual compression (MC). The primary efficacy end point was time to hemostasis (TTH), assessed at defined intervals from the start of treatment application, during a 10-min observational period. Safety end points (in Exploratory + Primary Studies) included adverse events (AEs), vital signs, physical assessments, common clinical laboratory tests (coagulation, complete blood count, serum clinical chemistry parameters, microscopic urinalysis), viral markers, and immunogenicity. In the Primary Study, the proportion of patients who achieved hemostasis at the 3-min time point was higher in the FS Grifols group (46.4%, n = 51/110) than in the MC group (26.3%, n = 15/57) (P < 0.05). The benefit was maintained at successive time intervals: 69 FS Grifols patients (62.7%) and 18 MC patients (31.6%) at 4 min; 82 FS Grifols patients (74.5%) and 28 MC patients (49.1%) at 5 min. The differences between the groups persisted for TTH ≤ 7 min and TTH ≤ 10 min. Treatment failure was reported for 13 FS Grifols patients (11.8%) and 16 MC patients (28.1%). TTH was shorter after FS Grifols application than after MC application. Differences were statistically significant in favor of FS Grifols for each TTH category and for the overall comparison (P < 0.001) as well as for each TTH category (cumulative) and for treatment failure (P = 0.016). Overall, AE experience and types of AEs reported were those expected in this patient population and were similar between the 2 treatment groups. The most frequently reported AEs were procedural pain (59.9% and 69.2% of patients in the FS Grifols [n = 72 + 111] and MC [n = 57] groups, respectively) and nausea (23.5% and 19.2% of patients, respectively). FS Grifols was efficacious and safe as an adjunct to anastomotic hemostasis in patients undergoing arterial surgery using prosthetic material with mild to moderate bleeding. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The effect of trace mineral source and concentration on ruminal digestion and mineral solubility.

PubMed

Genther, O N; Hansen, S L

2015-01-01

The objective of this experiment was to compare the effect of sources of sulfate trace mineral (STM) and hydroxy trace mineral (HTM) at different inclusions on digestibility of dry matter (DM) and neutral detergent fiber and solubility of Cu, Mn, and Zn in the rumen and abomasum of cattle. Five ruminally cannulated steers were used in a 5×5 Latin square design and individually fed a corn silage-based diet on an ad libitum basis. The 5 dietary treatments were as follows: control: no supplemental Cu, Mn, or Zn, analyzed to contain 7.4mg of Cu, 30.8mg of Mn, and 32.1mg of Zn per kilogram of diet DM (CON); low sulfate: 5mg of Cu/kg of DM supplemented from CuSO4, 15mg of Mn/kg of DM from MnSO4, and 30mg of Zn/kg of DM from ZnSO4; low HTM: 5mg of Cu/kg of DM supplemented from basic copper chloride (IntelliBond C; Micronutrients Inc., Indianapolis, IN), 15mg of Mn/kg of DM from manganese hydroxychloride (IntelliBond M; Micronutrients Inc.), and 30mg of Zn/kg of DM from zinc hydroxychloride (IntelliBond Z; Micronutrients Inc.); high sulfate: 25mg of Cu/kg of DM supplemented from CuSO4, 60mg of Mn/kg of DM from MnSO4, and 120mg of Zn/kg of DM from ZnSO4; and high HTM: 25mg of Cu/kg of DM supplemented from basic copper chloride, 60mg of Mn/kg of DM from manganese hydroxychloride, and 120mg of Zn/kg of DM from zinc hydroxychloride. Periods lasted for 12d, with 10d of diet adaptation. Dacron bags containing the CON total mixed ration were inserted on d 11 at 0h and were removed at 6, 12, 24, and 36h after insertion. Dry matter and neutral detergent fiber disappearances and rumen and simulated abomasal trace mineral solubilities were evaluated. Dietary treatment did not affect DM intake. Dry matter disappearance was lesser in supplemental TM treatments and greater in CON than the STM treatments, although the CON and HTM treatments did not differ. Neutral detergent fiber disappearance was not affected by treatment. Ruminally soluble Cu and Mn concentrations were least in CON and were lesser in HTM-containing treatments compared with STM treatments. However, in the abomasum, solubilities of Cu and Mn were similar across trace mineral sources. Ruminal and simulated abomasal soluble Zn was greater in the HTM treatments than in CON and STM, driven by the greater solubility of the high HTM treatment. Under the conditions of this study, supplementing trace minerals as STM decreased DM digestibility, whereas HTM did not affect DM digestibility. Additionally, Cu and Mn from HTM sources were relatively insoluble in the rumen but had similar solubility as STM at the pH found in the abomasum, suggesting that these minerals should be available for absorption in the intestine. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Hyper III on ramp

NASA Technical Reports Server (NTRS)

1969-01-01

The Hyper III was a full-scale lifting-body remotely piloted research vehicle (RPRV) built at what was then the NASA Flight Research Center located at Edwards Air Force Base in Southern California. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross-range reentry vehicles studied at Langley. (Hypersonic means Mach 5--five times the speed of sound--or faster; cross-range means able to fly a considerable distance to the left or right of the initial reentry path.) The FRC added a small, deployable, skewed wing to compensate for the shape's extremely low glide ratio. Shop personnel built the 32-foot-long Hyper III and covered its tubular frame with dacron, aluminum, and fiberglass, for about $6,500. Hyper III employed the same '8-ball' attitude indicator developed for control-room use when flying the X-15, two model-airplane receivers to command the vehicle's hydraulic controls, and a telemetry system (surplus from the X-15 program) to transmit 12 channels of data to the ground not only for display and control but for data analysis. Dropped from a helicopter at 10,000 feet, Hyper III flew under the control of research pilot Milt Thompson to a near landing using instruments for control. When the vehicle was close to the ground, he handed the vehicle off to experienced model pilot Dick Fischer for a visual landing using standard controls. The flight demonstrated the feasibility of remotely piloting research vehicles and, among other things, that control of the vehicle in roll was much better than predicted and that the vehicle had a much lower lift-to-drag ratio than predicted (a maximum of 4.0 rather than 5.0). Pilot Milt Thompson exhibited some suprising reactions during the Hyper III flight; he behaved as if he were in the cockpit of an actual research aircraft. 'I was really stimulated emotionally and physically in exactly the same manner that I have been during actual first flights.' 'Flying the Hyper III from a ground cockpit was just as dramatic as an actual flight in any of the other vehicles....responsibility rather than fear of personal safety is the real emotional driver. I have never come out of a simulator emtionally and physically tired as is often the case after a test flight in a research aircraft. I was emotionally and physically tired after a 3-minute flight of the Hyper III.'

Radio controlled mothership, Hyper III, and M2-F2 models on lakebed with research staff

NASA Technical Reports Server (NTRS)

1968-01-01

left to right: Richard C. Eldredge, Dale Reed, James O. Newman, Bob McDonald with the mothership (top) and other models. Over the years, the Dryden Flight Research Center and its predecessors has flown various models to gather data for various purposes. The mothership has been used to launch the models. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the full-sized Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross-range reentry vehicles studied at Langley. (Hypersonic means Mach 5--five times the speed of sound--or faster; cross-range means able to fly a considerable distance to the left or right of the initial reentry path.) The FRC added a small, deployable, skewed wing to compensate for the shape's extremely low glide ratio. Shop personnel built the 32-foot-long Hyper III and covered its tubular frame with dacron, aluminum, and fiberglass, for about $6,500. Hyper III employed the same '8-ball' attitude indicator developed for control-room use when flying the X-15, two model-airplane receivers to command the vehicle's hydraulic controls, and a telemetry system (surplus from the X-15 program) to transmit 12 channels of data to the ground not only for display and control but for data analysis. Dropped from a helicopter at 10,000 feet, Hyper III flew under the control of research pilot Milt Thompson to a near landing using instruments for control. When the vehicle was close to the ground, he handed the vehicle off to experienced model pilot Dick Fischer for a visual landing using standard controls. The flight demonstrated the feasibility of remotely piloting research vehicles and, among other things, that control of the vehicle in roll was much better than predicted and that the vehicle had a much lower lift-to-drag ratio than predicted (a maximum of 4.0 rather than 5.0). Pilot Milt Thompson exhibited some suprising reactions during the Hyper III flight; he behaved as if he were in the cockpit of an actual research aircraft. 'I was really stimulated emotionally and physically in exactly the same manner that I have been during actual first flights.' 'Flying the Hyper III from a ground cockpit was just as dramatic as an actual flight in any of the other vehicles....responsibility rather than fear of personal safety is the real emotional driver. I have never come out of a simulator emtionally and physically tired as is often the case after a test flight in a research aircraft. I was emotionally and physically tired after a 3-minute flight of the Hyper III.'

Hyper III on ramp with single-piece pivot wing installed & Princeton sailwing on ground, with Da

NASA Technical Reports Server (NTRS)

1969-01-01

The Hyper III's shape provided too little lift to land without some type of deployable wing. The single free flight was made using a simulated one-piece pivot wing, which was attached to the upper surface of the fuselage. This used a wing kit from an HP-11 sailplane, which was assembled by Daniel Garrabrant (shown in the photo). Another possible wing was the Flexible Princeton Sailwing. The piloted Hyper III flights were to be made using an SA-16B Albatross seaplane as the drop aircraft. The Hyper III would be carried under the SA-16B's wing on a drop-tank rack. Flight Research Center Director Paul Bikle asked NASA Headquarters for permission to exchange the Center's C-47 for the SA-16. Headquarters turned down this request, effectively ending the possibility of Hyper III flights with a pilot on board. The Flight Research Center (FRC--as Dryden was named from 1959 until 1976) already had experience with testing small-scale aircraft using model-airplane techniques, but the first true remotely piloted research vehicle was the Hyper III, which flew only once in December 1969. At that time, the Center was engaged in flight research with a variety of reentry shapes called lifting bodies, and there was a desire both to expand the flight research experience with maneuverable reentry vehicles, including a high-performance, variable-geometry craft, and to investigate a remotely piloted flight research technique that made maximum use of a research pilot's skill and experience by placing him 'in the loop' as if he were in the cockpit. (There have been, as yet, no female research pilots assigned to Dryden.) The Hyper III as originally conceived was a stiletto-shaped lifting body that had resulted from a study at NASA's Langley Research Center in Hampton, Virginia. It was one of a number of hypersonic, cross-range reentry vehicles studied at Langley. (Hypersonic means Mach 5--five times the speed of sound--or faster; cross-range means able to fly a considerable distance to the left or right of the initial reentry path.) The FRC added a small, deployable, skewed wing to compensate for the shape's extremely low glide ratio. Shop personnel built the 32-foot-long Hyper III and covered its tubular frame with dacron, aluminum, and fiberglass, for about $6,500. Hyper III employed the same '8-ball' attitude indicator developed for control-room use when flying the X-15, two model-airplane receivers to command the vehicle's hydraulic controls, and a telemetry system (surplus from the X-15 program) to transmit 12 channels of data to the ground not only for display and control but for data analysis. Dropped from a helicopter at 10,000 feet, Hyper III flew under the control of research pilot Milt Thompson to a near landing using instruments for control. When the vehicle was close to the ground, he handed the vehicle off to experienced model pilot Dick Fischer for a visual landing using standard controls. The flight demonstrated the feasibility of remotely piloting research vehicles and, among other things, that control of the vehicle in roll was much better than predicted and that the vehicle had a much lower lift-to-drag ratio than predicted (a maximum of 4.0 rather than 5.0). Pilot Milt Thompson exhibited some suprising reactions during the Hyper III flight; he behaved as if he were in the cockpit of an actual research aircraft. 'I was really stimulated emotionally and physically in exactly the same manner that I have been during actual first flights.' 'Flying the Hyper III from a ground cockpit was just as dramatic as an actual flight in any of the other vehicles....responsibility rather than fear of personal safety is the real emotional driver. I have never come out of a simulator emtionally and physically tired as is often the case after a test flight in a research aircraft. I was emotionally and physically tired after a 3-minute flight of the Hyper III.'