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Biomedical subjects

M D'Silva

Publications and source records attributed to M D'Silva.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effect of pancreas allografts on the ultrastructure of sciatic nerves in diabetic rats.

In a long-term study using cyclosporin-A (Cy-A) as immunosuppressant in a dose of 10 mg/kg/day, pancreas-duodenum was transplanted from Brown-Norway donors to alloxan-diabetic Lewis rats (n = 190). The pancreas transplants (PT) were performed after 1, 3, 6, 9, 12, and 15 months of diabetes. Recipient rats were sacrificed between 3 and 12 months of graft retainment. The mean axonal cross-sectional area and relative percentage of small, medium, and large myelinated fibers was evaluated. Also studied were unmyelinated fiber, ovoid body, and glycogen inclusion densities. Control rats consisted of non-diabetic rats (n = 36), similar rats receiving Cy-A (n = 42), diabetic rats (n = 103), and diabetic rats receiving Cy-A (n = 45). It was found that PT had a beneficial effect on the axonal cross-sectional area of myelinated nerves, the relative percentage of the various sizes of nerve fibers, and the ovoid body density, especially so in early diabetes. The effects in late diabetes were less spectacular. PT did not prove beneficial to the glycogen inclusion and unmyelinated fiber densities.

Animals↗
PubMed1990

Effect of pancreatic allografts on vascular basement membrane thickness in the diabetic rat.

Diabetic Lewis rats received pancreaticoduodenum allotransplants from Brown-Norway donors. Cyclosporine A (Cy-A) was used in a dose of 10 mg/kg/day for immunosuppression. These transplanted rats (n = 190) were compared with nondiabetic Lewis rats (n = 36), nondiabetic Lewis rats receiving 10 mg/kg/day Cy-A (n = 42), diabetic rats (n = 103), and diabetic rats receiving 10 mg/kg/day Cy-A (n = 45). The percentage area of periodic acid-Schiff (PAS) positive basement membrane (BM) of rectus muscle microvasculature was compared in each of the groups. It was found that the percentage area of PAS positive BM increased markedly over 15 months of uncontrolled diabetes. Cy-A did not have a significant effect on either normal or diabetic skeletal muscle vascular BM. Rats with established diabetes showed some reversal in the percentage area of PAS positive BM, when pancreas transplantation was performed at 9, 12, and 15 months of diabetes. Pancreas transplantation may appear beneficial even after the development of BM thickening of skeletal muscle vascular BM.

Abdominal Muscles↗
PubMed1990

Rat kidney transplantation update with special reference to vesical calculi.

A technical update on rat kidney transplantation is given. In this study, the bladder-bladder union was made using silk, polyglycolic acid (Dexon), polyglactin (Vicryl), and chromic catgut. The propensity of these sutures to form vesical calculi was investigated in both first and second generation transplants. The results of our study indicate that there is no significant difference (P greater than 0.01) in their calculogenic ability. Special problems attendant with first and second generation kidney transplants are described. The concept and technique of second generation kidney transplants are also described.

Animals↗
PubMed1990

Arterialization of the liver. II. Systemic pressure gradients in rats following variously sized arteriovenous fistulae.

Four groups (I, II, III, and IV) of six Wistar rats each were studied to elucidate the blood pressure changes following creation of arteriovenous fistulae (AVF) of diameters 1, 2, and 3 mm (groups II, III, and IV, respectively). Group I comprised normal rats with no AVF. Blood pressures were recorded in the carotid and femoral arteries, the femoral and portal veins, the right atrium, and the inferior vena cava (IVC) at renal vein (RV) and common iliac vein (CIV) levels. We found that AVF size did not disturb baseline carotid arterial or portal venous pressures (P greater than 0.01), but the femoral arterial pressures fell increasingly (P less than 0.01). On the other hand, right atrial pressure and that of IVC at RV and CIV levels rose substantially with increasing diameters of AVF (P less than 0.01). It was concluded that an AVF of 1 mm diameter least upset the normal blood pressures in the vessels examined.

Animals↗
PubMed1990

Arterialization of the liver. III. Influence of systemic and portal pressure gradients following heterotopic partial liver transplantation.

An acute study was designed to compare blood pressures across a heterotopically transplanted partial liver graft using arterialized and nonarterialized models. Eight partial liver transplants (PLT) were done in each group, using Wistar rats. The data gathered from them are the basis for the results obtained herein. Whereas there was no significant difference (P greater than 0.01) in inflow, outflow, or the pressure difference across the PLT between nonarterialized and arterialized groups, host portal venous pressures were significantly higher (P less than 0.01) in the arterialized group. A 1 mm arteriovenous fistula (AVF) was used to arterialize the PLTs in this study. It was proved that arterializing a PLT using a 1 mm AVF did not alter the pressure difference across the transplanted liver compared with the situation in the nonarterialized setting.

Animals↗
PubMed1990

Influence of the length of the small bowel graft on the severity of graft versus host disease.

The influence of the length and origin of a small bowel graft on graft versus host disease (GVHD) was studied in 33 (Lewis x brown Norway) F1 hybrids transplanted with different types of Lewis small bowel grafts. Recipients of an entire small bowel graft (N = 9), a jejunal graft (N = 6), or an ileal graft (N = 6) displayed a similar acute lethal GVHD, with 100% mortality rate and equivalent survival time (15 +/- 0.7, 16.8 +/- 0.9, and 16 +/- 0.6 days, respectively) (P greater than 0.01). On the other hand, 80% of the recipients of a segmental jejunal graft (N = 10) recovered from a transitory form of GVHD and regained weight similarly to the isografted rats (N = 4). It was concluded that the entire small bowel, jejunum, and ileum can provoke an equivalent GVHD after transplantation, whereas a segment of jejunum decreases the intensity of GVHD, probably by reducing the amount of transplanted lymphoid tissue.

Analysis of Variance↗
PubMed1989

Arterialization of liver transplants in rats: I. Application of the tissue perfusion monitor in hemodynamic studies.

This study demonstrates the use of the tissue perfusion monitor in the investigation of arterialization (using an arteriovenous fistula) of the heterotopic partial liver transplant. An index of peak perfusion rate was introduced as a reliable and accurate measure of the index of delivery rate of blood to the liver. Results revealed a significant (P less than .01) difference between arterialized and nonarterialized liver grafts when compared with their respective recipient host livers. Arterialization of grafted livers raised the index of peak perfusion rate to levels that were comparable to host livers. Arterialization also had a significant effect (P less than .01) on the host liver, whose values dropped by 74.26% when compared with the normal liver. Surprisingly, host values of the nonarterialized group fell by 61.54%. At this point, explanations for this phenomenon are speculatory. An extensive review of the literature exposes the variability in the observations of the role and usefulness of arterialization in hepatocellular function.

Anastomosis, Surgical↗
PubMed1989

Comparative functional study of Dexon and nylon microsutures in rat uterine anastomoses.

Forty-two female Wistar rats were used in a long-term study designed to evaluate the functional sequelae of employing 10-0 Dexon "S" and nylon microsutures in uterine anastomoses. Functional criteria used were the number of fetuses and live births, during and after pregnancy, respectively. Results indicate that the rats from both control and experimental groups were likely to have identical litter sizes for the first 3 deliveries (P greater than 0.01). An unexplained observation was the finding of a larger litter size for the experimental group rats at the fourth delivery as compared to its control counterpart (P less than 0.01). Also explicit is the propensity for the right uterine horn to bear a larger number of fetuses than its counterpart (P less than 0.01). Finally, neither suture was associated with a larger number of fetuses (P greater than 0.01). It was concluded that 1) uterine anastomosis did not prove detrimental to the functional outcome, 2) none of the sutures proved functionally superior, and 3) nylon was more likely to be associated with foreign body and inflammatory responses.

Anastomosis, Surgical↗
PubMed1989

Effect of arteriovenous fistula size on arterialized and host livers in rats.

In studying the hemodynamic relationship and behavior of peak blood flow indexes at different sizes of arteriovenous fistulas (AVF) using arterialized partial liver transplants (PLT), 96 male Wistar rats served as donors and recipients of heterotopic PLT in an acute phase study using ether anesthesia. AVF of 1, 2, and 3 mm were compared with a control group (0 mm) along the "index of peak perfusion rate" of blood flow, the dependent variable. We found that with increasing AVF sizes, a progressive fall in the peak blood flow in the host livers (P less than 0.01, r = -0.51) and a similar rise in the same index in the graft livers (P less than 0.01, r = +0.76) were documented. Also noted was a gradual fall in the cardiac pulsatility component of perfusion to both host and graft livers at AVF sizes of 2 and 3 mm. The same component of perfusion to host and graft livers was best at AVF size of 1 mm. It was concluded that a 1-mm AVF provided the best degree of arterialization to a PLT.

Animals↗
PubMed1987

Parameters altering the success of the one-anastomosis rat heart-lung transplant.

The single-anastomosis heart-lung transplantation method in the rat developed by Lee and associates has been examined and has proven to be simple and reproducible. Technical procedures are discussed emphasizing those procedures that require special caution to ensure successful graft function. The donor and recipient rat strain combination has been found to influence the success of the transplantation procedure. Rat strain combinations used in our laboratories resulted in different percentages of donor heart survival. Using Lewis rat (RT1 1/1) recipients, 68% of Brown Norway rat (RT1n/n) donor hearts and 97% of NBR rat (RT1 1/1) donor hearts survived. However, only 29% of Fischer rat (RT1 1/1) donor hearts survived longer than 2 days when transplanted into Lewis rat recipients. In our laboratories, the Lee method of single-anastomosis heart-lung transplantation has been used successfully to evaluate whether immunoregulatory compounds alter heart allograft rejection.

Animals↗
PubMedDate not supplied

Amiodarone-induced thyrotoxicosis: is there a place for surgery?

Amiodarone-induced hyperthyroidism has on most instances been reported as mild, and thyroid functions return to normal after discontinuation of the drug. Nevertheless, life-threatening amiodarone-induced thyrotoxicosis has also been described. Conventional treatments such as antithyroid drugs (thionamide) and corticosteroids are essentially ineffective or fail to alter the dramatic course of the thyroid crisis. This limited effectiveness of medical therapy, particularly in patients with previously neglected or unknown thyroid disease, prompted us to intervene surgically. We report a series of nine patients who underwent total or near-total thyroidectomy as a first-line therapy for five of them. Surgery resulted in rapid resolution of thyrotoxicosis with an uneventful postoperative course. This approach has the advantage of immediate effectivity, low risk of relapse, and appears to be the only treatment that permits continued therapy with amiodarone when the drug appears needed to control a life-threatening arrhythmia.

Aged↗
PubMedDate not supplied

[Surgical aspects of the treatment of adrenal gland diseases].

With the greatly enhanced accuracy of current endocrinologic diagnosis assisted by precise diagnostic imaging, together with greatly enhanced preparation of patients with endocrinopathy for safer anesthetic and surgical procedure (e.g. adrenal cortical cancers, cortisol and aldosterone producing adenomas and pheochromocytomas), operative procedures can be planned and conducted more precisely. For the surgeon, the strategy for treatment of functional and neoplastic disorders of the adrenal glands has essentially to consider the anatomy of the suprarenal glands, the deleterious effects of hormone excess before and during operation, the presumed nature of incidentally discovered adrenal mass and the size of the tumor.

Adrenal Gland Diseases↗
PubMedDate not supplied

The treatment of amiodarone-induced hyperthyroidism. Is there a place for surgery?

In many instances amiodarone-induced hyperthyroidism has been reported as mild, thyroid functions returning to normal after discontinuation of the drug. Nevertheless, life-threatening amiodarone-induced thyrotoxicosis has also been described. Conventional treatments such as with antithyroid drugs (Thionamide) and corticosteroids are essentially ineffective or fail to stop the dramatic course of the thyroid crisis. This limited efficacy of medical therapy, particularly in patients with previously--neglected or unknown--thyroid disease, prompted us to intervene surgically. We report a series of six patients who underwent total or nearly total thyroidectomy as first line therapy for four of them. Surgery resulted in rapid resolution of thyrotoxicosis with an uneventful postoperative course. This approach has the advantage of immediate and safe efficacy, low risk of relapse and finally, appears to be the only antithyroid treatment that permits continued therapy with amiodarone.

Amiodarone↗