Glomerular extracellular matrices in rat diabetic glomerulopathy by scanning electron microscopy

Characteristic pathological changes in the glomeruli in diabetic nephropathy include expansion of the mesangial matrix and thickening of the glomerular basement membrane (GBM). Using an acellular digestion technique combined with scanning electron microscopy, the three-dimensional ultrastructural changes in glomerular extracellular matrices were studied in rats with diabetic glomerulopathy. Diabetes was induced by the intravenous injection of streptozotocin and morphological analyses were performed 3, 6 and 11 months after the injection. Expansion of mesangial area and GBM thickening became evident with time. After treatment with the series of detergents, all cellular components were completely removed leaving the extracellular matrices intact. In normal controls, the mesangial matrix appeared as fenestrated septa with oval or round stomata between the glomerular capillaries. In diabetic glomerulopathy, expansion of mesangial matrix and narrowing of the mesangial fenestrae were observed. These changes in the mesangial matrices seem to play a vital role in the progression of glomerulosclerosis in rat diabetes. A subendothelial thin layer of the GBM was continuous with the mesangial matrix. One cause of GBM thickening in streptozotocin diabetes may be expansion of the mesangial matrix into the peripheral GBM.     

Effect of eosinophil peroxidase on beta-adrenergic receptor density on guinea pig lung membrane.

We studied whether eosinophil peroxidase (EPO), an eosinophil granule basic protein, can alter beta-adrenergic receptor (BAR) density on the guinea pig lung membrane. Lung membrane was first preincubated with 1-10 U/ml EPO and then incubated with 10(-4) M NaI and 10(-4) or 10(-6) M H2O2 for 2 hours. BAR density was determined using (-)125I-cyanopindolol. EPO combined with 10(-4) M H2O2 and I decreased the BAR density in a concentration-dependent manner. When only 10(-4) M H2O2 was used, the decrease in BAR density was small but significant. When compared to I, bromide was less effective and chloride alone was not effective. These results suggest that EPO is one of the factors responsible for beta-adrenergic blockade in asthma.     

A lymphocyte blastogenesis inhibitory factor (LBIF) reversibly arrests a human melanoma cell line, A375, at G1 and G2 phases of cell cycle

A lymphocyte blastogenesis inhibitory factor, LBIF, has been found in the culture supernatant of a human macrophage-like cell line, U937. The factor has been purified by fast protein liquid chromatography. Partial amino acid sequencing analysis showed that LBIF was a novel immunoregulatory factor. Recent study has demonstrated that LBIF possesses a remarkable tumor growth inhibitory activity. In this study, the cell growth inhibitory activity of LBIF was characterized on the proliferation of a human melanoma cell line A375 in vitro. LBIF strongly inhibits the proliferation of A375 cells. The inhibitory activity was cytostatic and reversible by Day 5 although the lethal effect became apparent at Day 7. Cell cycle analysis by flow cytometry showed that LBIF arrested A375 cells at both G₁ and G₂/M phases. Mitotic index analysis indicated that A375 cells were arrested in G₁ and G₂ phases. LBIF function was not attributed to the elevation of intracytoplasmic cyclic-AMP levels. Thus, these results suggest that LBIF plays an important role in controlling cell cycle and there is a similarity between the mechanisms of G₁ and G₂ arrests in eukaryotic cell proliferation. LBIF-induced reversible cell-cycle arrest of A375 cells can be a useful system to analyze the signal transduction for cell proliferation and cell-cycle arrest.     

Comparative studies of the effects of carcinogenic and antitumor agents on the DNA replication of cultured mammalian cells

Cultured mouse L₅₁₇8Y cells were exposed to several carcinogenic and antitumor agents. After exposure to one of the agents, the cells were label with [³H]-thymidine for 20 min, and the DNA was subjected to alkaline sucrose gradient centrifugation immediately or after a chase period. This led us to classify the agents into 3 groups: (1) UV, 4-nitroquinoline-1-oxide (4NQO), N-methyl-N′-nitrosoguanidine (MNNG), nitrogen mustard and Mitomycin C. These were characterized by 20-min DNA labeling patterns showing the formation of small DNA and by the slowing down of their subsequent elongation. Replicated DNA strands would have gaps where “damage” was present on the parental strands. Subsequently, gap-filling replication would occur with or without repairing damage. (2) γ-rays. The 20-min DNA labeling profile displayed a larger size of DNA pieces and the subsequent elongation of this DNA was slightly affected. This probably due to a preferential depression of initiation DNA replication. (3) Methyl methanesulfonate (MMS) and low temperature (28°). The 20-min DNA labeling patterns were qualitatively similar to, but quantitatively different from those of non-irradiated control. The rate of DNA elongation was slightly retarded.     

Immunohistochemical changes of somatostatin cells in the pancreatic islets of rats after streptozotocin administration.

By the enzyme-labeled antibody method, cells containing somatostatin (SRIF) as well as insulin or glucagon were identified in pancreatic islets of the rat. SRIF antiserum was raised in rabbits followin immunization with synthetic SRIF coupled with human serum alpha-globulin and did not cross-react with hypothalamic, pituitary or gastrointestinal hormones using our immunoassay method. In the control rats, SRIF-containing cells were scattered in the periphery of the islets in close proximity to the outer glucagon containing cells. These latter cells were distributed in the outermost periphery of the islets. Insulin-containing cells were located in the central portion of the islets and dominantly occupied most of the islet. In the streptozotocin-diabetic rat, SRIF-containing cells were significantly increased in number whereas insulin-containing cells were markedly reduced. It is suggested from these findings that the number as well as the distribution of SRIF-, insulin- and glucagon-containing cells was important to the physiological and pathophysiological functioning of the islet.     

pH dependency of kinetic parameters and reaction mechanism of beef liver catalase.

The pH-dependence of the kinetic parameters in H2O2 decomposition by beef liver catalase was investigated. At pH 7.0, the ternary complex (ESS) decomposition rate was about 100 times faster than ESS formation (42 microM H2O2), and the value of the Michaelis constant was 0.025 M. From ethanol competition experiments, two different proton dissociation constants of the enzyme (pKe1 = 5.0, pKes2 = 5.9) were obtained for the binding of first and second H2O2 molecules. Another pKa value (pKes1) of 4.2 was obtained from the pH dependence of overall rate constant (ko). The reaction mechanism of catalase was discussed in relation to these ionizable groups.     

Characterization of Functional Primary Cilia in Human Induced Pluripotent Stem Cell-Derived Neurons

Neurochemical Research - Recent advances in human induced pluripotent stem cells (hiPSCs) offer new possibilities for biomedical research and clinical applications. Neurons differentiated from...     

Invasive invertebrates associated with highly duplicated gene content

Invasion of alien species has led to serious problems, including the destruction of native ecosystems. In general, invasive species adapt to new environments rapidly, suggesting that they have high genetic diversity that can directly influence environmental adaptability. However, it is not known how genomic architecture causes genetic diversity that leads to invasiveness. Recent studies have showed that the proportion of duplicated genes (P_D) in whole animal genomes correlate with environmental variability within a habitat. Here, we show that P_D and propagule size significantly explain the differences in species categories (invasive species, noninvasive species, and parasites). P_D correlated negatively with the propagule size. The residual values of regression of P_D on propagule size revealed that the invasive species had higher P_D values and larger propagule size than those of the noninvasive species, whereas the parasites had lower P_D values and smaller propagule size than those of others. There were no correlations between the invasive species and other genomic factors including the genome size, number of genes, and certain gene families. Our results suggest that the P_D values of a genome might be a potential genomic source causing genetic variations for adaptation to diverse environments. The results also showed that the invasiveness status of a species would be predicted by the residual values of regression of P_D on propagule size. Our innovative approach provides a measure to estimate the environmental adaptability of organisms based on genomic data.