Secondary collapsing glomerulopathy associated with Loa loa filariasis

This is the first case of nonprimary collapsing focal segmental glomerulosclerosis (FSGS) associated with Loa loa filariasis. Loa loa micofilariae were detected on a blood smear after a patient presented with nephrotic syndrome (NS), microhematuria, and renal failure. The renal biopsy showed a collapsing glomerulopathy variant of FSGS. Microfilariae also were identified in renal microvasculature, including the afferent arterioles and the glomerular and peritubular capillaries.     

Gene-based neurotransmitter modulation in cerebellar granule neurons

The human glutamic acid decarboxylase (GAD) gene was transferred into rat cerebellar granule neurons. Following adenoviral-mediated gene transfer, nearly 100% of the neurons had transgene expression that persisted for the duration of their survival in culture. GABA levels were elevated both in the growth media and in lysates of GAD-modified granule neurons. In GAD-modified neurons, extracellular GABA levels steadily increased with time, whereas intracellular GABA levels peaked 10 days after gene transfer. GAD-modified neurons released both glutamate and GABA into the surrounding media before and after potassium-induced stimulation, but only the release of glutamate was sensitive to potassium stimulation. These data suggest that glutamatergic neurons, which initially contained no detectable GABA, can be genetically modified to release GABA constitutively.     

Identification of surface tegumental antigens of normal and irradiated schistosomula

Sodium dodecyl sulphate- poly acrylamide gel electronphoresis (SDS-PAGE) fractionation of tegumental surface antigens (STEG-Ags.) of 7-day cultured normal and irradiated schistosomula showed no obvious qualitative differences. The observed polypeptide bands of both normal irradiated STEG-Ags. were almost identical and have similar corresponding molecular weights. The immunoblotting assay, using different types of mouse sera, revealed similarity between the bands of both normal and irradiated STEG-Ags. recognized by each type of mouse serum. No qualitative rather than quantitative differences have been observed. The quantitative differences were reflected in intensively staining of some bands from normal STEG-Ag. rather than their corresponding bands of the same molecular weights from irradiated STEG-Ag.     

Extracellular signal-regulated activation of Rap1 fails to interfere in Ras effector signalling

The small GTPase Rap1 has been implicated in both negative and positive control of Ras-mediated signalling events. We have investigated which extracellular signals can activate Rap1 and whether this activation leads to a modulation of Ras effector signalling, i.e. the activation of ERK and the small GTPase Ral. We found that Rap1 is rapidly activated following stimulation of a large variety of growth factor receptors. These receptors include receptor tyrosine kinases for platelet-derived growth factor (PDGF) and epithelial growth factor (EGF), and G protein-coupled receptors for lysophosphatidic acid (LPA), thrombin and endothelin. At least three distinct pathways may transduce a signal towards Rap1 activation: increase in intracellular calcium, release of diacylglycerol and cAMP synthesis. Surprisingly, activation of endogenous Rap1 fails to affect Ras-dependent ERK activation. In addition, we found that although overexpression of active Rap1 is able to activate the Ral pathway, activation of endogenous Rap1 in fibroblasts does not result in Ral activation. Rap1 also does not negatively influence Ras-mediated Ral activation. We conclude that activation of Rap1 is a common event upon growth factor treatment and that the physiological function of Rap1 is likely to be different from modulation of Ras effector signalling.     

An accurate stable isotope dilution gas chromatographic-mass spectrometric approach to the diagnosis of guanidinoacetate methyltransferase deficiency

A gas chromatography-mass spectrometry (GC-MS) method is described for the quantification of guanidinoacetate in different body fluids, using a two step derivatisation procedure which involves a reaction with hexafluoroacetylacetone to form a bis(trifluoromethyl)pyrimidine ring structure followed by a reaction with pentafluorobenzyl bromide. 13C2-labelled guanidinoacetate is used as an internal standard. Bis(trifluoromethyl)pyrimidine pentafluorobenzyl derivatives were separated on a polar capillary GC-column and were quantified using negative chemical ionisation mass fragmentography. The detection limit of the method is 1 pmol guanidinoacetate in a 100 microl sample. Control values were obtained for urine (53.9 +/- 25.9 mmol mol(-1) creatinine), plasma (1.08 +/- 0.31 micromol l(-1)), cerebrospinal fluid (CSF) (0.114 +/- 0.068 micromol l(-1)) and amniotic fluid (3.44 +/- 0.64 micromol l(-1)). The applicability of the method is illustrated by the determination of guanidinoacetate in urine, plasma and CSF of a patient affected with guanidinoacetate methyltransferase deficiency. In all body fluids of this patient, guanidinoacetate was highly elevated.     

Preoperative and intraoperative topographic diagnosis of insulinomas

Altogether 120 patients with organic hyperinsulinism underwent clinical examination and treatment (38 male, 82 female, mean age 44.2 +/- 4.6 years). The cause of hyperinsulinism was benign insulinomas in 96 (80.0%), malignant tumors in 9 (7.5%), and hyperplasia of beta cells in 6 (5.0%). In 9 (7.5%) patients the origin of hyperinsulinism was not diagnosed. The tumor was localized in the head, body, and tail of the pancreas in 31.8%, 36.4%, and 31.8% of cases, respectively. Intraoperative ultrasonography (IOUS) was undertaken in 37 patients, and in 83 cases only intraoperative palpation was done. Arterial stimulated venous sampling (ASVS) was performed in 17 patients (blood was sampled from the right hepatic vein for determination of the insulin level after arterial stimulation by calcium gluconate in different parts of the pancreas). The sensitivity of ultrasonography (US) was 29.5%, computed tomography (CT) 24.2%, angiography 55.9%, superselective angiography (branches of the celiac trunk) 72.2%, and intraoperative palpation 90.0%. ASVS showed an accuracy of 90.0%. Combining angiography with ASVS gave an exact diagnosis of hyperinsulinism in 100% of cases, and IOUS revealed tumors in 100% of cases. Hyperplasia of beta-cells was diagnosed only by means of ASVS. A total of 117 patients underwent surgery, including distal resection of pancreas (n = 39), enucleation of tumor (n = 70), and laparotomy (n = 8). The postoperative mortality associated with insulinomas was 7.7%. The frequency of postoperative complications was 43.6%. Benign insulinomas recurred at a rate of 5.4%. Patients with malignant insulinomas had a 5-year survival of 66.0%. The diagnosis of insulinomas was achieved by a combination of selective angiography, ASVS, and IOUS.     

Studies on experimental mixed infection of Schistosoma haematobium and Schistosoma mansoni

Swiss Albino mice have been infected with S. haematobium and challenged 4 weeks later with S. mansoni. Parasitological, pathological and ultrastructural studies were done. The results revealed cross mating between the two species. A reduction in S. mansoni worm load, egg count, hepatic granuloma number and size was noticed. The presence of heterologous immunity was suggested.     

Increasing efficiency from censored survival data by using random effects to model longitudinal covariates

When estimating a survival time distribution, the loss of information due to right censoring results in a loss of efficiency in the estimator. In many circumstances, however, repeated measurements on a longitudinal process which is associated with survival time are made throughout the observation time, and these measurements may be used to recover information lost to censoring. For example, patients in an AIDS clinical trial may be measured at regular intervals on CD4 count and viral load. We describe a model for the joint distribution of a survival time and a repeated measures process. The joint distribution is specified by linking the survival time to subject-specific random effects characterizing the repeated measures, and is similar in form to the pattern mixture model for multivariate data with nonignorable nonresponse. We also describe an estimator of survival derived from this model. We apply the methods to a long-term AIDS clinical trial, and study properties of the survival estimator. Monte Carlo simulation is used to estimate gains in efficiency when the survival time is related to the location and scale of the random effects distribution. Under relatively light censoring (20%), the methods yield a modest gain in efficiency for estimating three-year survival in the AIDS clinical trial. Our simulation study, which mimics characteristics of the clinical trial, indicates that much larger gains in efficiency can be realized under heavier censoring or with studies designed for long term follow up on survival.     

Rapid resolution of chylous ascites after liver transplantation using somatostatin analog and total parenteral nutrition

Chylous ascites is the accumulation of chylomicronrich lymphatic fluid within the peritoneal cavity. It is a rare complication of retroperitoneal surgery, and may occur spontaneously in 0.5% of patients with cirrhosis. Its management is controversial, and despite a variety of treatment options with limited efficacy, the course is usually indolent. In this article, we report a case of rapid resolution of chylous ascites after liver transplantation following 10 days of treatment using somatostatin analog (Octreotide, 100 micrograms sc. t.i.d.) and total parenteral nutrition (TPN). A 55-year-old man underwent liver transplantation for hepatitis C cirrhosis, and developed an infected chylous fistula on the 10th day. Treatment by fasting, TPN, and somatostatin analog resulted in a rapid falloff in fistula output, with complete resolution of ascites within 2 days. This is the first report, to our knowledge, of somatostatin analog and TPN used in combination for rapid and successful closure of a chylous fistula.