Increased level of apolipoprotein B mRNA in the liver of ventromedial hypothalamus lesioned obese rats

The mRNA level of apolipoprotein B (apoB), which is a principal protein component of nascent very low density lipoprotein (VLDL), was determined in parallel with the measurement of acetyl-coenzyme A (Ac-CoA) carboxylase activity in the liver of ventromedial hypothalamus (VMH) lesioned obese rats. Eight weeks after the electrolysis of the bilateral VMH, the level of apoB mRNA in the VMH-lesioned rats was about 1.5-fold higher than that in the sham-operated rats, indicating increased apoB synthesis in the liver of the VMH-lesioned obese rats. The activity of Ac-CoA carboxylase, which is a rate-limiting enzyme for the fatty acid biosynthesis, was about 1.8-fold higher in the VMH-lesioned rats. These observations indicated that VLDL synthesis is increased in the liver of VMH-lesioned obese rats.     

Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats An immunohistochemical study

Summary Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450_MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450_MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa.     

Prostaglandin D2 diminishes transmucosal potential difference in rat colonic mucosa in vitro in contrast to the increasing effect of prostaglandin E1

The effect of Prostaglandin D2 (PGD2) on ion transport was investigated in the rat colon in vitro. Ion transport across the intestinal mucosa was estimated by transmucosal potential difference (PD) and short circuit current (Isc) in the Ussing chamber. PGD2 added to the serosal reservoir induced a sustained reduction in PD and Isc at the concentration of higher than 10(-7)M, producing the maximal decrease at 10(-5)M. PGD2 at 10(-5)M completely blocked the increase in PD elicited by prostaglandin E1 (PGE1), theophylline, dibutyryl cAMP or serotonin. Adenylate cyclase activity was determined in the colonic mucosal homogenates after addition of PGD2 and PGE1. Treatment with PGD2 or PGE1 caused a significant increase in the enzyme activity. Combined treatment with both prostaglandins induced no more increase than that elicited by PGE1 alone. These results suggest that PGD2 has an anti-secretory effect on the rat colon and it may regulate the ion transport process through other mechanism than the modification of cyclic AMP concentration in mucosal cells.     

Marked increase in gastric histidine decarboxylase activity in patients with hypergastrinemia.

Histidine decarboxylase (HDC) activity and histamine content were measured in endoscopic gastric biopsy specimens of 19 control subjects with normogastrinemia and 6 patients with hypergastrinemia. In controls, the HDC activity was 3 fold higher in fundic mucosa (120 +/- 13 fmol/min/mg protein, mean +/- S.E.) than in antral mucosa (39 +/- 5 fmol/min/mg protein). In patients with hypergastrinemia, an extremely high HDC activity (713 +/- 181 fmol/min/mg protein) was observed in fundic mucosa, although the HDC activity in antral mucosa was not significantly different from that of controls. The histamine content in fundic mucosa was also significantly higher in patients with hypergastrinemia than in controls but no significant difference was seen in histamine content in antral mucosa between the two groups. These results are compatible with the hypothesis that in man, as well as in rat, histamine synthesis in fundic mucosa is enhanced by gastrin.     

Morphological aspects on pancreatic islets of non-obese diabetic (NOD) mice

The pancreatic islets of female non-obese diabetic (NOD) mice (a model of insulin-dependent diabetes mellitus), have been examined by both light and electron microscopy. At about the age of 2 weeks, mononuclear cells began to infiltrate in or near the islets and some of these cells were in contact with the islet cells. Following this degeneration of islet B-cells took place, the process occurring in two ways. In many cells numerous secretory granules with extremely dense cores occupied the cytoplasm. Other cells, however, were filled with low-density secretory granules and the nuclei of these cells became pycnotic. After degeneration of B-cells, the islets were effaced by numerous mononuclear cells. With the onset of the diabetic state these mononuclear cells gradually disappeared, and thereafter small islets remained. By electron microscopy, retrovirus-like particles were observed in cisternae of the rough endoplasmic reticulum in islet B-cells at all stages. With an anti-retrovirus serum (goat anti-KiMSV-NIHxeno serum), positive immunofluorescence was observed in some pancreatic islet cells of NOD mice aged 1 day and 4, 6, 8, 9, 10 and 14 weeks. It is suggested that these virus particles may be intimately related to the inflammatory reaction occurring in the islets and to the development of diabetes mellitus.     

Effect of intraluminal bile or bile acids on release of gut glucagon-like immunoreactive materials in the dog

The true biological role of gut glucagon-like immunoreactive materials (gut GLI) is still unknown, although the stimulatory effect of intraluminal nutrients on the secretion of gut GLI has been described. The present authors, using the canine intestinal loop prepared from the terminal portion of the ileum, investigated how gut GLI would respond to digestive juice or its components. When bladder bile collected from another dog and diluted to 10% in saline was instilled into canine ileal loop, gut GLI in a branch of regional mesenteric vein was elevated significantly. Cholic acid suspended in saline (0.25 g/50 ml) also stimulated gut GLI secretion in the similar pattern to that of bile administration. On the other hand, 154 mM NaHCO3 which is a major inorganic component of pancreatic juice did not affect the venous level of gut GLI.     

Gravitropism of maize and rice coleoptiles: dependence on the stimulation angle

Gravitropism of maize and rice coleoptiles was investigated with respect to its dependence on the angle of displacement or the initial stimulation angle (ISA). Close examination of curvature kinetics and the response to a drop in stimulation angle (SA) indicated that the gravtropic response during an early but substantial part of the curvature development is directly related to the ISA, there being no effect of the reduction of SA resulting from the curvature response itself. On the basis of this finding, the relationship between the steady SA and the curvature rate was determined. In maize, the curvature rate increased linearly with the sines of SAs up to an SA of 90 degrees. Rice coleoptiles, however, showed a saturation curve in the same range of SAs. The saturation profile was nearly identical between coleoptiles grown in air and those submerged in water, although the latter elongated much faster. Rice coleoptiles appeared to be far more sensitive to gravity than maize coleoptiles. It is concluded that the sensitivity to gravity, assessed through dependence on ISA, is a property inherent to a given gravitropic organ. Long-term measurements of curvature indicated that the coleoptiles bend back past the vertical. This overshooting was marked in submerged rice coleoptiles.     

Enhancement of aromatic amino acid-nucleic acid base stacking interaction by metal coordination to base: fluorescence study on a tryptophan-Pt(II)-guanine ternary complex

In order to investigate the effect of the Pt(II) ion on the stacking interaction between tryptophan and a guanine base, the quenching of Trp fluorescence was monitored for some systems in the absence and presence of the metal ion, and the association constants were obtained by the analysis of Eadie-Hofstee plots. All spectral data suggested that the stacking interaction is enhanced by the Pt(II) coordination to the guanine N7 atom. The result indicates the importance of the metal ion as a bookmark in the specific recognition of a nucleic acid base by an aromatic amino acid residue.