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Biomedical subjects

K Ishihara

Publications and source records attributed to K Ishihara.

At least 649 records · Page 36Linked to original sources
PubMed1987

[Hydronephrosis in pregnancy and its etiology].

Using ultrasonography, the cause and incidence of hydronephrosis were investigated in humans and rabbits and the following results were obtained. The degree of hydronephrosis was classified into grade I (calyceal diameter; up to 5 mm) to grade V (calyceal diameter; 21 mm or more). In normal non-pregnant women, the calyceal diameter was within grade I. The hydronephrosis was found in 45.5-87.0% of pregnant women in the right kidney and in 29.1-51.0% in the left. Throughout pregnancy, the incidence was significantly higher in the right than in the left. On the 6th puerperal day, the incidence of hydronephrosis was lowered, but the diameter did not return to the non-pregnant level. Comparison of women who practised swimming during pregnancy and those who did not reveal the incidence of hydronephrosis was lower in the swimming group than in the non-swimming. In rabbits, calyceal dilatation increased as gestation advanced and hydronephrosis was found in progesterone-treated ovariectomized rabbits. It was concluded that the hydronephrosis in the 1st trimester was due to increased steroid hormones, but also that, in the 2nd trimester, the combined effect of hormones and mechanical obstruction was responsible for its occurrence.

Adult↗
PubMed1986

Aniracetam augments, and midazolam inhibits, the long-term potentiation in guinea-pig hippocampal slices.

The effects of aniracetam, a nootropic drug, and midazolam, which produces amnesia, on the long-term potentiation (LTP) of population spikes was investigated using hippocampal slices (CA3 area) from the guinea pig. Aniracetam at concentrations of 10(-7) and 10(-8) M, but not at 10(-6) M, significantly augmented LTP. On the other hand, midazolam (10(-9) M) significantly suppressed LTP. The suppressive effect was antagonized by Ro 15-1788 (10(-8) M). Both drugs did not affect the population spikes in the absence of tetanic stimulation at those concentrations. It was suggested that in vitro application of LTP is a feasible model system for evaluating the nootropic activity of drugs.

Animals↗
PubMed1986

Different effects of dynorphin A on in vitro guinea pig hippocampal CA3 pyramidal cells with various degrees of paired-pulse facilitation.

We investigated the effects of dynorphin A (Dyn A), a heptadecapeptide, on the population spikes of the guinea pig hippocampal CA3 pyramidal neurons, in vitro, using paired-pulse stimulation of the mossy fibers. Dyn A produced facilitatory and inhibitory effects on the population spikes in the preparations with lower and higher degrees of paired-pulse facilitation, respectively. Morphine and D-Ala2, D-Leu5-en-kephalin, mu- and delta-agonist, respectively, predominantly potentiated the population spikes, while kappa-agonists such as U-50, 488H and bremazocine mainly caused an inhibition. These results suggest that Dyn A has two separate (excitatory and inhibitory) effects on the guinea pig hippocampal CA3 neurons through mu-(delta) and kappa-opioid receptors, respectively.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1986

Comparative study on mucus glycoproteins in rat stomach and duodenum.

The density of mucus glycoprotein compared to that of the corpus, antrum and duodenum was; 1.52, 1.49 and 1.57 g/ml respectively. Carbohydrate composition of gastrointestinal mucus glycoprotein consisted of N-acetylgalactosamine, N-acetylglucosamine, galactose, fucose and sialic acid. Ratios of carbohydrate composition among corpus, antral and duodenal mucus glycoproteins differed. The average length of an oligosaccharide was found to be about 12-13, 14 and 10 sugars in the corpus, antrum and duodenum, respectively. In the corpus, the amino acid content was found to have the following quantitative order: Thr greater than Ser greater than Glx = Pro; in the antrum: Thr greater than Ser greater than Glx; and in the duodenum: Thr greater than Ser greater than Pro. Corpus, antral and duodenal mucus glycoproteins have the blood-group A antigen; antral mucus glycoprotein in particular exhibited strong blood-group A activity.

Animals↗
PubMed1986

Thyrotropin-releasing hormone and insulin in chemically induced pancreatic islet cell tumors in rats.

Thyrotropin-releasing hormone (TRH) and insulin were measured by radioimmunoassay in acetic-acid extracts of 19 pancreatic islet cell tumors induced by streptozotocin and nicotinamide in rats. In addition, gel filtration properties of TRH-immunoreactivity and immunoreactive insulin (IRI) were examined in 5 and 14 tumors, respectively. TRH was demonstrated in 10 of 19 tumors, with a mean of 166 +/- 47 (SEM) pg/mg wet weight, whereas the concentration was less than 3 pg/mg wet weight in the other tumors. In contrast, all tumors contained IRI, with a mean of 11.0 +/- 1.6 micrograms/mg wet weight. Ten tumors in which TRH was demonstrated contained more IRI than those in which TRH was not detected (13.1 +/- 1.8 vs 6.5 +/- 1.7 micrograms/mg wet weight, P less than 0.02). After gel filtration, all TRH immunoreactivity was eluted at the same place as synthetic TRH in the 5 tumors. In addition, gel filtration elutes showed essentially the same pattern of IRI in the 14 tumors, with 3 peaks. The predominant IRI peak comigrated with marker insulin (95.7 +/- 0.8%), another prominent peak occurred coincident with proinsulin standard (3.3 +/- 0.5%), a third peak was present in the void volume (0.28 +/- 0.04%). These distributions of IRI were similar to those in extracts of normal pancreases. The present studies demonstrate TRH immunoreactivity in pancreatic islet cell tumors induced by streptozotocin and nicotinamide in rats. Chemically induced insulinomas can serve as a model for insulin storage which is analogous to islet B cells.

Adenoma, Islet Cell↗
PubMed1986

Virus-neutralizing antibodies to hepatitis B virus: the nature of an immunogenic epitope on the S gene peptide.

Using a murine monoclonal antibody (RF-HBs-1) which has been shown to be capable of neutralizing both ad and ay subtypes of hepatitis B virus (HBV), we have devised a competitive inhibition assay to measure the presence of virus-neutralizing antibodies in the sera of patients who have recovered from acute type B hepatitis. The majority of patients have this antibody in their serum. We also show that this antibody inhibits the binding of polymerized human serum albumin (pHSA) to the pHSA receptor site of the HBV particle, which has been proposed as an important site for the entry of HBV into liver cells. We have demonstrated that the epitope recognized by this antibody is dependent on the linkage of 24,000 and 28,000 mol. wt. polypeptides via a disulphide bond. This conformational determinant in the coat of the virus which is part of or near to the pHSA binding site is important in evoking a virus-neutralizing response.

Antibodies, Monoclonal↗
PubMed1986

Effect of cimetidine on gastric mucus glycoprotein biosynthesis.

The effects of cimetidine on gastric mucus glycoprotein biosynthesis in rat gastric mucosa were investigated using organ culture technique. 2 h following oral administration of cimetidine (40 mg/kg body weight), corpus tissue was placed in the organ culture. Mucus glycoprotein synthesis was accelerated to 137% of control (p less than 0.01). In order to investigate the direct effect of cimetidine on mucus glycoprotein biosynthesis, corpus tissue was cultured in the medium containing cimetidine. 100 microM cimetidine enhanced mucus glycoprotein biosynthesis to 174% (p less than 0.01). Cimetidine was found to stimulate gastric mucus glycoprotein biosynthesis both in vivo and in vitro.

Animals↗