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Biomedical subjects

R Vohra

Publications and source records attributed to R Vohra.

At least 19 recordsLinked to original sources
PubMed1996

The relative effectiveness of estrone, estradiol-17 beta, and estriol in sex reversal in the red-eared slider (Trachemys scripta), a turtle with temperature-dependent sex determination.

In many turtles the temperature during the middle of incubation determines the gonadal sex of the hatchling. Sex steroid hormones have been implicated in temperature-dependent sex determination in the red-eared slider turtle, Trachemys scripta; nonaromatizable androgens are involved in male sex determination and estrogens and aromatizable androgens in female sex determination. Administration of exogenous estradiol-17 beta to eggs incubating at a temperature that normally produces only males can overcome the effect of temperature and result in all offspring being female. Further, estradiol-17 beta and incubation temperature synergize to produce a greater feminizing effect at intermediate incubation temperatures that produce mixed sex ratios. This study demonstrates that, in the red-eared slider, there is a complex interaction between incubation temperature, different estrogens, and the dosage effect of each hormone. There are changes in potency of different estrogens with incubation temperature such that estriol is more potent than estrone and estradiol-17 beta at 26 degrees (an all-male producing incubation temperature), estrone and estriol are equipotent to each other and more potent than estradiol-17 beta at 28.8 degrees (an incubation temperature that produced a male-biased sex ratio), and estradiol-17 beta is more potent than estrone and estriol at 29 degrees (an incubation temperature that produced equal numbers of males and females). These changes may be due to differences in synergism between the hormones and incubation temperature. Estriol treatment also resulted in cranially hypertrophied oviducts at all incubation temperatures in a dose-dependent manner, whereas animals treated with estradiol-17 beta and estrone had normal oviducts. These results support the hypothesis that estrogens are involved in the final common pathway of female sex determination in this species.

Animals↗
PubMed1996

Imaging in phaeohyphomycosis of the brain: case report.

A case of multiple, conglomerated brain abscesses due to Xylohypha bantiana, with unique imaging features, is presented. This is the first culture-proven case of brain infection due to this fungus in the neuroimaging literature.

Brain Abscess↗
PubMed1995

Tuberculosis of the elbow. A report of 10 cases.

We treated 10 cases of tuberculosis of the elbow with a 9-month antitubercular drug regimen, and surgery when indicated. The diagnosis was confirmed in 8 cases by histopathological examination and 2 cases were treated on clinical radiographic grounds. The follow-up ranged from 1 year to 3 years. The results were excellent in synovial and extraarticular lesions. Only in cases with minimal involvement of articular cartilage was a good range of movement achieved.

Adolescent↗
PubMed1994

Cerebral oxygen saturation, transcranial Doppler ultrasonography and stump pressure in carotid surgery.

Transcranial Doppler ultrasonography (TCD) of the middle cerebral artery (MCA), light-reflective cerebral oximetry and measurement of internal carotid artery stump pressure were compared as methods of monitoring cerebral perfusion during carotid surgery in 33 patients. Median cerebral oxygen saturation was 70 (range 62-85) per cent and TCD-measured mean blood velocity 42 (range 19-91) cm/s before carotid cross-clamping, falling to 68 (53-83) per cent and 16 (0-50) cm/s respectively on application of the clamps (P < 0.001). Stump pressure correlated closely with MCA blood velocity 30 s after the start of cross-clamping (rs = 0.58, P < 0.001), but not with cerebral oxygen saturation. A fall of 5 per cent or more in cerebral oxygen saturation following cross-clamp application was predicted by a decrease in mean MCA blood velocity of at least 60 per cent. Changes in cerebral oxygen saturation correlated significantly with systolic blood pressure throughout the perioperative period (rs = 0.41, P < 0.001). Significant falls in cerebral oxygenation were not predicted by low stump pressure but were associated with large reductions in the mean MCA blood velocity measured by TCD.

Blood Flow Velocity↗
PubMed1992

An improved means of faecal diversion: the trephine stoma.

Twenty-four patients in whom trephine stoma formation was performed over a 4-year period are described. This procedure permits the formation of an end ileostomy or colostomy without laparotomy. It is simple, rapid, safe and allows speedy recovery. It is widely applicable and previous abdominal surgery is no contraindication. The procedure was impossible in two patients who required laparotomy and in a third in whom a loop colostomy was created. Operation time was shorter and postoperative opiate requirements less than when laparotomy was undertaken for stoma formation. Follow-up (median 1 year) of 17 patients confirmed a low incidence of complications (two prolapses, one parastomal hernia) after trephine stoma formation. This procedure is recommended as the preferred method of ileostomy or colostomy formation when laparotomy is not otherwise indicated.

Adult↗
PubMed1992

Endothelial cell seeding: a review.

The concept of endothelial cell seeding, designed to provide vascular grafts with a nonthrombogenic lining, has progressed from crude animal experiments during the past two decades to detailed in vitro functional studies using human cells. Although favorable results have been obtained in animal studies this has yet to be translated to humans, where current application of these techniques has been limited to a very few clinical trials. The history, current status and future directions are reviewed herein.

Animals↗
PubMed1992

Purification and kinetics of extracellular phospholipase A of Salmonella newport.

Attempts were made to purify and study the kinetics of extracellular phospholipase A of Salmonella newport (6,8, eb; 1,2). The enzyme was purified by salt precipitation followed by gel filtration, using different grades of Sephadex. The enzymically active purified preparation was found to be a protein, having molar mass ranging between 43 and 67 kDa. The enzyme had a pH optimum at 7.5, giving 18.2 micrograms of lysophosphatidylcholine per mg protein. Its activity was enhanced by all metal ions except potassium, by solvents and surfactants except sodium dodecyl sulfate. It hydrolyzed the membrane phospholipids of red blood cells and was inhibitory to the growth of other microorganisms.

Chromatography, Gel↗
PubMed1992

Management of neutropenic colitis.

Neutropenic colitis is recognized as a rare complication of chemotherapy in haematological malignancies. By contrast, the complication is less well known in relationship to chemotherapy for solid malignancies. There are very few examples reported and this paper adds three further cases and reviews the literature. We emphasize that although some cases of neutropenic colitis may be managed medically, full thickness involvement of the bowel wall may lead to perforation and require surgery. The pathogenesis of this progression is discussed and it is concluded that clinical awareness is important in the diagnosis. The signs of peritonitis or septicaemia are indications for excisional surgery with the formation of a temporary ileostomy.

Adrenal Gland Neoplasms↗
PubMed1992

The response of rapidly formed adult human endothelial-cell monolayers to shear stress of flow: a comparison of fibronectin-coated Teflon and gelatin-impregnated Dacron grafts.

Endothelial cells labeled with indium 111-oxine were seeded in supraconfluent densities onto fibronectin-coated expanded polytetrafluoroethylene (ePTFE) and gelatin-impregnated Dacron graft segments. These grafts with rapidly formed endothelial-cell monolayers were then exposed to varying shear stresses at flow rates of 200 and 300 ml/min, using tissue culture medium in an artificial flow circuit. As the loss of radioactivity represented endothelial-cell loss, cell retention was calculated by the ratio of counts recorded at different time points during 2 hours of flow to initial counts. Although initial cell adherence to gelatin-impregnated Dacron graft segments was poor compared to ePTFE, once cells were attached they resisted shear stress of flow better at 200 ml/min and equally well at 300 ml/min. The cell retention on fibronectin-coated ePTFE was 55.4 +/- 12.9% at 200 ml/min and 56.5 +/- 15.2% at 300 ml/min; cell retention for gelatin-impregnated Dacron graft segments was 69.0 +/- 6.0% and 66.5 +/- 5.5%, respectively. Qualitatively scanning electron microscopy of both ePTFE and gelatin-impregnated Dacron graft segments showed patchy coverage of grafts with cells. There was preferential attachment of endothelial cells to the nodes on ePTFE, although on gelatin-impregnated Dacron graft segments, cells conformed to the Dacron fibers at different levels and directions with evidence of bridging in the gaps between individual fibers. This study shows conclusively that rapidly formed endothelial-cell monolayers on ePTFE and gelatin-impregnated Dacron graft segments resisted a shear stress of flow equal to that seen in a femoropopliteal vein graft with significant cell retention at 2 hours.

Blood Vessel Prosthesis↗
PubMed1991

Comparison of different vascular prostheses and matrices in relation to endothelial seeding.

Thin-walled expanded polytetrafluoroethylene (ePTFE), woven Dacron and gelatin-impregnated Dacron (Gelseal) vascular grafts were compared, the grafts being coated with three different matrices: collagen IV, fibronectin and preclot matrix. In addition, untreated ePTFE and Gelseal were examined. The graft segments, coated with these matrices, were incubated with radiolabelled adult human endothelial cells for 30, 60 and 90 min. Endothelial cell adherence was calculated from the ratio of radioactive counts in the grafts to counts in grafts plus supernatants. Endothelial cell attachment to untreated grafts was poor, but a suitable matrix significantly improved adherence. All three matrices tested gave good results, although preclot was best; 30-60 min incubation was sufficient for optimum cell attachment. Cell adherence to both Dacron and ePTFE was significantly better than to Gelseal. The type of prosthetic polymer and the substrate protein coating used to promote endothelial cell adherence are two important factors which may determine the ultimate success of endothelial seeding in the operating room.

Blood Vessel Prosthesis↗
PubMed1991

An anomalous right iliac artery presenting as iliac stenosis.

An anatomical anomaly of pre-aortic inferior vena cava and retro-psoas iliac artery in a 33-year-old female is reported. This patient presented with severe right leg claudication and was successfully managed by implantation of an aortofemoral graft.

Adult↗
PubMed1991

In vitro adherence and kinetics studies of adult human endothelial cell seeded polytetrafluoroethylene and gelatin impregnated Dacron grafts.

Lining the luminal surface of small diameter vascular prostheses with living endothelial cells reduces thrombogenicity, decreases infection and improves patency. In vitro adherence and kinetics studies of adult human endothelial cell seeded Polytetrafluoroethylene (ePTFE) and Gelatin impregnated Dacron (Gelseal) were performed. Endothelial cell adherence on ePTFE and Gelseal coated with collagen IV, fibronectin and preclot matrices was compared. Untreated ePTFE and Gelseal were also used. Ten graft segments in each group coated with these matrices were incubated with radio-labelled adult human endothelial cells for 30, 60 and 90 min. Labelled endothelial cells seeded in supra-confluent densities on fibronectin coated ePTFE and Gelseal grafts were used for kinetic studies. Resultant endothelial cell monolayers were then exposed to varying shear stress at flow rates of 200 and 300 ml/min in an artificial flow circuit. Endothelial cell attachment to untreated grafts was poor and a suitable matrix significantly improved adherence with fibronectin and preclot but less so with collagen. A 30 min incubation was sufficient for optimum cell attachment. Cell adherence to ePTFE was significantly better than Gelseal. Scanning electron micrographs (SEM) of ePTFE showed preferential attachment to the nodes whilst on Gelseal, cells conformed to Dacron fibres at different levels and directions. Rapidly formed endothelial cell monolayers on ePTFE and Gelseal grafts resisted shear stress of flow with significant cell retention at 2 h. There was patchy coverage of both grafts with evidence of bridging of gaps between individual fibres in Gelseal.

Blood Vessel Prosthesis↗
PubMed1991

The role of the perforated segment of the ventricular catheter in cerebrospinal fluid leakage into the brain.

Two cases of gross post-operative cerebrospinal fluid (CSF) leakage along an indwelling ventricular catheter are reported. The CSF appeared to leak through the perforations of the ventricular catheter, as well as at the site of penetration of the ventricular wall. A small or slit ventricle with high intraventricular pressure may thus be a predisposing factor for this localized CSF collection.

Catheters, Indwelling↗
PubMed1991

Acute aortocaval fistula in association with ruptured aortic aneurysm.

Eight cases of aortocaval fistula are described. In all of them operation was performed with repair of the fistula and replacement of the aneurysm by a prosthetic graft. In seven cases the cause was rupture of an atherosclerotic aneurysm but one case followed rupture of a re-entrant dissecting aortic aneurysm. A fistula is most easily recognized by the sensation of a palpable thrill over the aorta during operation together with systemic venous congestion and a high central venous pressure before aortic clamps are applied. Diagnosis of the fistula before surgery or its recognition during operation and before opening the aorta usually leads to a successful outcome.

Acute Disease↗
PubMed1991

Factors affecting limb salvage and mortality in patients undergoing femoral embolectomy.

The management and outcome of 131 acute femoral arterial occlusions in 126 patients over a period of 7 years is presented. The emboli were of cardiac origin in 82% of cases; 96% of the patients were treated with thromboembolectomy. The overall mortality rate was 26% with a limb salvage rate of 88% amongst the survivors. There was an increased risk of mortality in patients having both atrial fibrillation and myocardial infarction, saddle emboli and those having delayed embolectomy after 24 h. Only the latter was found to be statistically significant. One-third of the patients who died had a failed embolectomy. An early fasciotomy helped in preventing permanent neurological deficit in patients with compartment syndrome.

Acute Disease↗
PubMed1991

Arterial emboli to the arm.

A review of 46 episodes of arterial emboli to the arm in 44 patients is presented. Two-thirds of cases were of cardiac origin whereas subclavian artery abnormality was responsible for 14%. Thirty-six per cent had axillary occlusion, 52% had a brachial lesion, and the lesion was distal to the elbow in 11%. Of the 36 patients treated surgically, 33 retained a viable arm with a palpable radial pulse in 26. Of the ten patients with 'failed first embolectomy', six technical failures were revised successfully, retaining a viable hand in all of them. The other four failures had evidence of organized intraluminal thrombus; one had been induced by anti-thrombin III deficiency. Three of this latter group lost limbs. Because delay leads to irreversible ischaemic changes, there seems to be an understandable bias in favour of early surgical exploration in equivocal cases.

Adult↗
PubMed1990

Long-term survival in patients undergoing resection of abdominal aortic aneurysm.

The long-term survival of patients undergoing abdominal aortic aneurysm surgery is presented. Three-hundred and thirty-eight patients who presented with elective, urgent, or emergency abdominal aortic aneurysms, have been followed retrospectively for five years. We found no statistical difference in the long-term survival in these three groups of patients. As expected patients who had successful operation survived better than patients who were not offered surgery because of their poor medical condition. Interestingly, advancing years, history of myocardial infarction or hypertension did not significantly influence long-term survival.

Adult↗