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Biomedical subjects

A R Moossa

Publications and source records attributed to A R Moossa.

At least 91 records · Page 5Linked to original sources
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

Inhibition of insulin release by cyclosporine and production of peripheral insulin resistance in the dog.

Cyclosporine has been shown to cause glucose intolerance in both humans and animals. This can result from alterations in insulin release, insulin metabolism, the sensitivity of peripheral or hepatic tissues to insulin, or a combination of these factors. The present study was designed to simultaneously evaluate the effect of CsA on these variables. A group of chronically catheterized dogs were administered oral CsA (20 mg/kg/day) for a period of 10 weeks. The glucagon stimulation test (GST) and the euglycemic glucose clamp technique, using a primed continuous infusion of 3H-3-glucose and a continuous insulin infusion (0.8 mU/kg/min), were employed to evaluate pancreatic insulin release, peripheral glucose disposal rate (Rd), hepatic glucose output (HGO), and metabolic clearance rate (MCR) of insulin. The dogs were tested before and after 2, 6, and 10 weeks of CsA administration. Serum CsA levels were 358 +/- 85, 244 +/- 48, and 355 +/- 81 ng/ml at 2, 6, and 10 weeks, respectively (P = NS). Elevated fasting glucose and an abnormal glucose response to an i.v. bolus of glucagon (0.25 U) were noted after 2, 6, and 10 weeks of CsA administration. The areas under the glucose curve (AUCG) for 0-60 min were 9605 +/- 773, 11634 +/- 1226, 12380 +/- 719, and 12626 +/- 1560 mg/min/dl at 0, 2, 6, and 10 weeks, P(F3, 15 = 5.1) = 0.012, demonstrating a CsA-induced disturbance of glucose homeostasis. The areas under the insulin curve (AUCI) for 0-20 min of the insulin response curve were 2033 +/- 203, 1089 +/- 187, 1038 +/- 179, and 972 +/- 161 uU/min/dl at 0, 2, 6, and 10 weeks, P(F3, 15 = 13.1) less than 0.001, indicating a 50% reduction during CsA treatment. CsA did not affect basal Rd, but peripheral insulin resistance was noted in the insulin-stimulated state. Rd during the third hour of the insulin infusion decreased from 6.72 +/- 0.69 to 4.42 +/- 0.44, 5.02 +/- 0.64, 4.47 +/- 0.52 mg/kg/min at 0, 2, 6, and 10 weeks, respectively, P(F3, 15 = 6.94) less than 0.004. HGO suppression by insulin and MCR of insulin were not altered by CsA. Similarly, glucagon secretion did not appear to be influenced by CsA. In conclusion, this study has simultaneously evaluated the effect of CsA on several aspects of glucose and insulin metabolism in the dog. CsA administration produces abnormal glucose homeostasis by reducing pancreatic insulin release, in addition to inducing peripheral insulin resistance.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The role of interventional radiology for complications of cholecystectomy.

This report summarizes diagnostic and therapeutic radiologic procedures in 45 patients who suffered major complications from cholecystectomy. Complications were divided into (1) bile duct injury or ligation and (2) a variety of pathologic fluid collections. Specific lesions were bile duct injury (n = 6), accidental bile duct ligation (n = 12), ductal stricture (n = 12), abscess (n = 11), biloma (n = 7), hematoma (n = 5), infected pancreatic pseudocyst (n = 3), and stones (n = 2). Presenting problems were sepsis, jaundice, and intermittent cholangitis. The patients underwent 104 interventional radiologic procedures including 29 percutaneous transhepatic cholangiograms, 21 percutaneous biliary drainages, 12 balloon dilatations of strictures, drainage of 11 abscesses, 8 bilomas, 5 hematomas, and 3 pancreatic pseudocysts. Stones were removed by baskets in 2 patients; 12 pressure and perfusion studies were performed. One hundred of 104 procedures were successful; there was one failed biliary drainage, one unsuccessful stricture dilatation, one unsuccessful hematoma drainage, and one recurrent biloma. Thirty patients were spared another operation. The percutaneous procedures were beneficial although not curative in 14 of 15 patients who underwent reoperation; in those patients the procedures helped to establish a diagnosis, improve the patient's preoperative status, or serve as a landmark for the surgeon to locate and repair the ligated or injured duct. One patient died after reoperation, a 2.2% mortality rate. Sectional imaging studies combined with interventional radiologic procedures help to diagnose promptly and effectively treat major complications of cholecystectomy. These interventional procedures either cure the complication and obviate reoperation or aid the surgeon by relieving sepsis and jaundice before reoperation and providing an intraoperative guide for bile duct reconstruction.

Adult↗
PubMed1989

Serum enzymes and other laboratory tests in acute pancreatitis.

This review evaluates selective enzymes and blood tests available for the diagnosis and prognosis of acute pancreatitis. It is concluded that serum amylase and lipase measurements represent the best available diagnostic methods. Newer alternative assays still require careful evaluation.

Acute Disease↗
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

Effects of cyclosporin A on the splenic tissue of rats: a histomorphometric analysis.

Histological studies demonstrated that long-term cyclosporin A treatment of nonantigenically challenged (untransplanted and unimmunized) Lewis rats markedly reduces the total percentage of splenic white pulp when compared to untreated control spleens (mean = 24 vs 34%, P less than 0.001). Direct measurements of periarteriolar sheaths and marginal zones demonstrated a marked reduction in size of these compartments in cyclosporin A-treated rats compared to untreated controls (P less than 0.001). In addition, there was a striking reduction in cellular density of the periarteriolar sheaths (P less than 0.001) and a minimal reduction in cellular density of the marginal zones (P less than 0.1) in the cyclosporin A-treated group when compared to untreated controls. There was no significant difference in total splenic size between the cyclosporin A-treated and the control groups, as indicated by total cross section measurements (mean = 33.3 vs 35.0, P less than 0.4). Qualitative observations of methyl green-pyroninophilic cells within and surrounding the marginal zones of the cyclosporin A-treated spleens revealed a much greater proportion of large pyroninophilic lymphocytes, which suggests that they are B immunoblasts. We conclude that long-term cyclosporin A treatment depletes splenic periarteriolar sheaths and marginal zones, compartments known to contain primary T lymphocytes, and induces an immunoblastic cell proliferation within the marginal zones and red pulp as well.

Animals↗
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↗
PubMed1988

Long-term studies of pancreas allotransplantation in experimental diabetes mellitus.

Pancreaticoduodenal (PD) allografts (Brown Norway-alloxan-diabetic rats, n = 190) were treated with cyclosporin A (Cy-A) 10 mg/kg/daily and compared with nondiabetics with Cy-A treatment (n = 55), diabetics (n = 50), and diabetics with Cy-A treatment (n = 45). Body weight, blood sugar, blood insulin, blood urea nitrogen (BUN), and creatinine were monitored periodically; there were marked elevations of BUN and creatinine levels, indicating probably nephrotoxicity of Cy-A at this dosage. Some islet cell atrophy in the PD allografts was noted at the conclusion of the study. With respect to the immunosuppressive effect of Cy-A in alloxan diabetic rats, Brown Norway PD transplants into Lewis rats were successful and free of rejection for as long as 15 months post-transplantation. The body weight of these PD transplanted rats, however, never approached values representative of the nondiabetic rats. In our experience, the PD allograft model is acceptable in the clinical situation, particularly in children if the microsurgical technique is mastered and if the Cy-A regimen is used in combination with other immunosuppressant(s).

Animals↗
PubMed1988

Histometric investigations of the effect of cyclosporin A on the testicular tissue of rats.

The effect of cyclosporin A (CsA) on rat testes was assessed in Lewis rats which were given 10 mg/kg of CsA im per day. The rats were divided into 13 subgroups, and 1 subgroup was sacrificed each month. The rat testes were measured and examined for histometrical and morphological changes in comparison to controls. Histometrical analysis included testicular cross-sectional surface area, tubular density, tubular diameter, and the amounts of testicular germinal epithelium, lumen, and interstitial tissue. In the parameters examined, there were no overall differences between CsA-treated animals and controls. CsA does not affect rat testicular tissue.

Age Factors↗
PubMed1987

Surgical treatment of chronic pancreatitis: an overview.

The correct management of chronic pancreatitis remains undecided. The aims of surgical treatment are to relieve pain, treat complications and preserve pancreatic function. The appropriate surgical procedure to achieve these ends must be carefully chosen.

Chronic Disease↗
PubMed1987

Survival in 1001 patients with carcinoma of the pancreas.

Among 1001 patients with carcinoma of the pancreas, 23 of 912 patients with exocrine carcinomas, 10 of 46 with ampullary carcinomas, and 21 of 43 with malignant islet cell tumors survived 3 years. Of the survivors with exocrine cancers, there were nine of 97 patients who had curative operation, two had had palliative resections only, and one was an incidental microfocal carcinoma; in the remaining 11 patients a histologic origin in the pancreas was not established. Preoperatively suspected and histologically proven 3-year survivors included six patients with ductal adenocarcinomas, three patients with mucinous cystadenocarcinomas, one patient with acinic cell carcinoma, and one patient with microadenocarcinoma. Only two patients can be considered cured. Tumor size and lymph node status did not correlate with survival. Cystadenocarcinomas comprised 1% of cases but one third of 3-year survivors. Long-term survival in histologically confirmed pancreatic carcinoma is a rare event that cannot be predicted in the individual case.

Aged↗
PubMed1987

Selective suppression of hepatic glucose output by human proinsulin in the dog.

By using the euglycemic glucose-clamp technique we have observed the effects of comparable low dose proinsulin and insulin infusions on isotopically determined glucose turnover in 20 anesthetized dogs. In each animal somatostatin (SRIF) infusion was used to suppress endogenous pancreatic hormone secretion and basal glucagon was replaced. Peripheral proinsulin (0.083 micrograms X kg-1 X min-1) and insulin (350 microU X kg-1 X min-1) levels 15- to 20-fold higher than insulin on a molar basis, based on previous observations that proinsulin has only 5-10% the biologic potency of insulin. Three groups of infusion studies were performed: SRIF and glucagon (n = 5); SRIF, glucagon, and proinsulin (n = 10); and SRIF, glucagon, and insulin (n = 5). The mean serum proinsulin level of 2.43 +/- 0.36 pmol/ml achieved represented a 17-fold excess compared with the mean serum insulin level of 0.14 +/- 0.03 pmol (20 +/- 4 microU/ml). At these concentrations, both hormones reduced hepatic glucose production rates by approximately 50% to 2.0 +/- 0.2 mg X kg-1 X min-1 and 1.8 +/- 0.5 mg X kg-1 X min-1, respectively. In contrast, proinsulin failed to stimulate peripheral glucose utilization, whereas insulin led to a 2.0 +/- 0.3 mg X kg-1 X min-1 increment (approximately 50% increase) in glucose uptake (P less than 0.05). Thus at low infusion rates proinsulin exerts its effect predominantly by suppressing hepatic glucose production without measurable stimulation of peripheral glucose disposal. In contrast, for a comparable degree of hepatic glucose output suppression, insulin also significantly stimulates glucose disposal.

Animals↗
PubMed1987

Non-insulin-mediated glucose uptake predominates in postabsorptive dogs.

Overall glucose uptake represents the sum of insulin-mediated glucose uptake (IMGU) and non-insulin-mediated glucose uptake (NIMGU). In this study, we compared the rate of NIMGU in conscious and anesthetized dogs. Rates of glucose disposal were compared in the basal state and during severe insulinopenia after endogenous insulin suppression by high-dose somatostatin (SRIF) infusion. Steady-state NIMGU rates were calculated 2 h after commencing SRIF infusion. Three groups of studies were performed: 1) SRIF in conscious dogs; 2) SRIF in anesthetized dogs; and 3) SRIF plus glucagon, also in anesthetized dogs. In all three groups, serum insulin levels were reduced to below assay sensitivity after SRIF infusion. The basal metabolic clearance rate of glucose (MCRg) for each group was 3.8 +/- 0.4, 3.6 +/- 0.3, and 3.6 +/- 0.3 ml X kg-1 X min-1, respectively (P = NS, all groups). Steady-state NIMGU rates were 2.4 +/- 0.2 (conscious), 2.5 +/- 0.1 (anesthetized, SRIF only), and 2.4 +/- 0.1 ml/kg/min (anesthetized, SRIF plus glucagon). Thus, absolute rates of NIMGU expressed as MCRg in conscious and anesthetized animals do not differ and in the three groups studied comprise approximately the same proportion of the basal glucose uptake (approximately 64, approximately 69, and approximately 66%, respectively). We conclude that approximately 66% of basal postabsorptive glucose uptake occurs via NIMGU mechanisms and that this pathway is unaffected by anesthesia and surgery.

Absorption↗
PubMed1987

Hypoglycemic syndrome in infancy and childhood. A surgeon's perspective.

Persistent, severe hypoglycemia due to inappropriate or excessive insulin secretion is an infrequent but devastating metabolic emergency in infancy and childhood. The primary therapeutic goal is to normalize blood glucose levels and to prevent the catastrophic sequelae of permanent brain damage and mental retardation due to refractory hypoglycemia. Overall, the use of diazoxide, the mainstay of medical treatment, has proved disappointing and has led to the reevaluation of aggressive, early surgical intervention. Currently, subtotal (80% to 90%) pancreatectomy is the most widely used operative procedure in the treatment of hyperinsulinism. It is, however, still associated with a relatively high failure rate, particularly in neonates or during early infancy when either nesidioblastosis or islet cell hyperplasia-both diffuse proliferative beta-cell disorders-is the most common cause of inappropriate insulin secretion. In these cases, "total" or "near-total" pancreatectomy may be necessary to control the hypoglycemic crisis.

Child↗
PubMed1986

The role of clinical and biochemical criteria and endoscopic retrograde cholangiopancreatography in the urgent diagnosis of common bile duct stones in acute pancreatitis.

The role of clinical and biochemical criteria in predicting common bile duct (CBD) stones was analyzed in 76 patients with acute pancreatitis undergoing endoscopic retrograde cholangiopancreatography (ERCP) during the same hospital admission. Forty patients had ERCP within 72 hours; cholangiography was successful in 92%. Fifty patients had biliary pancreatitis; 25 patients had CBD stones and all were successfully removed by endoscopic sphincterotomy (ES). Twenty-six patients had nonbiliary pancreatitis. Two patients had complications from ERCP and/or ES; two patients died (no CBD stones) but ERCP was noncontributory. Significant differences were found between the biliary and nonbiliary disease groups with respect to age, and bilirubin. gamma-glutamyl transpeptidase, alkaline phosphatase, alanine transaminase, and amylase levels. The first four factors also discriminated between those patients with and without CBD stones. Logistic discriminant functions were estimated providing probabilities for the presence of CBD stones for each patient but were too cumbersome for clinical use. A simple scoring system was devised on the basis of cut-off levels: bilirubin greater than or equal to 40 mumol/L, gamma-glutamyl transpeptidase greater than or equal to 250 IU/L, alkaline phosphatase greater than or equal to 225 IU/L, and age greater than or equal to 70 years, indicating CBD stones. Bilirubin alone had a sensitivity and specificity of 80%; the specificity increased to 93% with all four factors. These results suggest that clinical and biochemical criteria and ERCP and/or ES may have important roles in the management of patients with suspected biliary pancreatitis.

Acute Disease↗