Electrophoretic analysis of the RNA of avian tumor viruses

The heat-dissociated RNA of avian leukosis and sarcoma viruses of several subgroups was analyzed by polyacrylamide gel electrophoresis. Heterogeneous patterns obtained in early experiments appeared to be due primarily to RNA degradation during steps of RNA characterization by sucrose gradient centrifugation rather than procedures of virus purification, virus incubation at 37°, or RNA extraction. All the viruses studied contained a major RNA species with an estimated size between 2.5 and 2.8 × 10⁶ daltons and at least one minor RNA species of slightly smaller size. This suggests that if the genome of avian tumor viruses is indeed segmented, the subunits are of a similar size. The heat-dissociated RNA of RAV-2, RAV-60, RAV-50, and Schmidt-Ruppin RSV (subgroup A) was generally less complex than that of Schmidt-Ruppin RSV (subgroup D). No significant difference was found in the RNA of RAV-2 grown in chicken cells that were positive or negative for the expression of latent viral genes (chf). However, in the absence of other known leukosis viruses, the pattern of heat-dissociated RNA of Bryan RSV grown in cells expressing chf functions was consistently broader than that of Bryan RSV grown in cells not expressing chf functions.     

HLA-DP and susceptibility to insulin-dependent diabetes mellitus in Japanese

ABSTRACT: Human leukocyte antigen (HLA) genes are candidates for susceptibility genes in insulin-dependent diabetes mellitus (IDDM). Recently, the association of DR and DQ with IDDM has been reported, but the role of HLA-DP genes remains uncertain. To address the question, we analyzed the DPB1 gene of 20 Japanese IDDM patients and 30 control subjects using a combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis (PCR-RFLP method). DPB1*0501 was the most frequent allele both in Japanese patients and control subjects. There was no appreciable association between IDDM and the DPB1 allele in Japanese. The absence of association between IDDM and DP, in spite of the known association between this disease and both DR and DQ, suggests that the HLA locus (loci) telomeric to DP encodes susceptibility to IDDM.     

Temperature-sensitive membrane association of pp60src in tsNY68-infected cells correlates with increased tyrosine phosphorylation of membrane-associated proteins

Incubation of membrane vesicles from normal and Rous sarcoma virus-transformed chick embryo fibroblasts (CEF) with [gamma-32P]ATP resulted in the phosphorylation of a large number of proteins. The major differences observed between the membrane vesicles of untransformed and transformed cells were: (1) a 5- to 10-fold increase in the proportion of labeled phosphotyrosine in transformed vesicles and (2) the phosphorylation of pp60src in vesicles from transformed cells. Of the many proteins labeled in vitro, only pp60src was immunoprecipitated by TBR serum. Phosphorylation of the immunoprecipitated pp60src occurred on tyrosine in the 26-kDa carboxy-terminal Staphylococcus aureus V8 protease fragment. pp60src was not phosphorylated in vitro in membrane vesicles prepared from tsNY68-infected cells grown at the nonpermissive temperature. The proportion of labeled phosphotyrosine in membrane proteins from tsNY68-infected cells grown at the nonpermissive temperature was only slightly increased relative to that observed in membranes prepared from normal cells. Subcellular fractionation indicated that while pp60src was membrane associated in tsNY68-infected cells grown at the permissive temperature, pp60src was chiefly soluble in tsNY68-infected cells grown at the nonpermissive temperature. Temperature-sensitive membrane association of pp60src in tsNY68-infected cells was also observed by indirect immunofluorescence microscopy. When membranes were prepared from tsNY68-infected cells that had been downshifted from the nonpermissive to the permissive temperature, the reappearance of in vitro phosphorylated pp60src and the increase in the proportion of labeled phosphotyrosine in membrane vesicles correlated with the kinetics of src immune complex kinase reactivation and membrane association of pp60src.     

A novel subtype of type 1 diabetes mellitus characterized by a rapid onset and an absence of diabetes-related antibodies. Osaka IDDM Study Group

BACKGROUND AND METHODS: Type 1 diabetes mellitus is now classified as autoimmune (type 1A) or idiopathic (type 1B), but little is known about the latter. We classified 56 consecutive Japanese adults with type 1 diabetes according to the presence or absence of glutamic acid decarboxylase antibodies (their presence is a marker of autoimmunity) and compared their clinical, serologic, and pathological characteristics. RESULTS: We divided the patients into three groups: 36 patients with positive tests for serum glutamic acid decarboxylase autoantibodies, 9 with negative tests for serum glutamic acid decarboxylase antibodies and glycosylated hemoglobin values higher than 11.5 percent, and 11 with negative tests for serum glutamic acid decarboxylase antibodies and glycosylated hemoglobin values lower than 8.5 percent. In comparison with the first two groups, the third group had a shorter mean duration of symptoms of hyperglycemia (4.0 days), a higher mean plasma glucose concentration (773 mg per deciliter [43 mmol per liter]) in spite of lower glycosylated hemoglobin values, diminished urinary excretion of C peptide, a more severe metabolic disorder (with ketoacidosis), higher serum pancreatic enzyme concentrations, and an absence of islet-cell, IA-2, and insulin antibodies. Immunohistologic studies of pancreatic-biopsy specimens from three patients with negative tests for glutamic acid decarboxylase autoantibodies and low glycosylated hemoglobin values revealed T-lymphocyte-predominant infiltrates in the exocrine pancreas but no insulitis and no evidence of acute or chronic pancreatitis. CONCLUSIONS: Some patients with idiopathic type 1 diabetes have a nonautoimmune, fulminant disorder characterized by the absence of insulitis and of diabetes-related antibodies, a remarkably abrupt onset, and high serum pancreatic enzyme concentrations.     

Terbutaline-induced triphasic changes in volume of rat alveolar type II cells: the role of cAMP

Changes in the volume of rat alveolar type II cells (AT-II cells) induced by terbutaline, a beta(2)-agonist, were measured using video-enhanced contrast microscopy. The changes consisted of three phases: initial cell shrinkage, cell swelling, and gradual cell shrinkage. The initial cell shrinkage was Ca(2+)-dependent and was inhibited by quinine (a K+ channel blocker). The subsequent cell swelling was cAMP-dependent and was inhibited by amiloride (a Na+ channel blocker). The final cell shrinkage was cAMP-dependent and was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB, a Cl- channel blocker). Thus, terbutaline-induced cell volume changes were regulated by both Ca2+ and cAMP. Accumulation of cAMP alone, however, induced the Ca2+ -dependent cell shrinkage of AT-II cells and H-89 (a PKA inhibitor) inhibited terbutaline-induced cell volume changes. This suggests that cAMP accumulation stimulates the Ca2+ signal during terbutaline stimulation. In conclusion, terbutaline stimulates not only Na+ influx, but also K+ and Cl- release mediated via cAMP accumulation in rat AT-II cells, which induces the triphasic cell volume changes.     

Anisotropic diffusion in kidney: apparent diffusion coefficient measurements for clinical use

The purpose of this study was to evaluate anisotropy of the kidney by measurements of the apparent diffusion coefficient (ADC) using commercially available magnetic resonance (MR) imaging. Fifty-one consecutive patients underwent diffusion-weighted echoplanar MR imaging of the upper abdomen with five different strengths of motion probing gradients (b = 1.51, 55.3, 36.6, 317, and 932 sec/mm2) applied along the z-axis. Four ADC values for the upper pole and central portion of the kidney were calculated from four different b-value ranges and compared. The ADCs for the kidney calculated in the lower b-value ranges were significantly higher than those in the higher ranges. The ADCs for the upper pole portion were significantly higher than those for the central portion except for one in the highest b-value range. Diffusion in the kidney is anisotropic, probably due to the kidney's radially oriented structures such as renal vessels and tubules.