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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 541 records · Page 30Linked to original sources
PubMed1988

[The mode of delivery and neonatal outcome in breech presentations less than 32 weeks' of gestation].

This study was undertaken to determine the effect of the delivery method on neonatal outcome in fetal breech presentation, and the following results were obtained. The rate of cesarean section for breech presentations was 70.7% (104/147). 1) There were 18 neonatal deaths (41.9%) in 43 vaginal breech deliveries compared to 8 (7.7%) in 104 cesarean breech deliveries. Neonatal deaths were significantly higher in vaginal breech deliveries than cesarean breech deliveries (p less than 0.001). 2) In breech presentations, intracranial hemorrhages were more common among vaginally born infants (44.2% vs. 25.0%; p less than 0.02), but the incidence of idiopathic respiratory distress syndrome (39.5% vs. 28.8%) did not differ significantly between vaginal and cesarean infants. 3) In singletons delivered vaginally, fetal distress was more common among breech presentations than vertex presentations (83.3% vs. 46.3%; p less than 0.02). 4) In vaginally delivered breech singletons, there was no neonatal death among infants with more than 4 one minute Apgar scores, and there was no significant difference between neonatal death and the no neonatal death groups with regard to gestational weeks and birth weight.

Breech Presentation↗
PubMed1988

[The relationship between clinical diagnosis and placental findings in 561 placentae delivered less than 32 weeks' of gestation].

The relationship between clinical diagnosis and placental findings for 561 consecutive cases of delivery at 24 to 31 weeks' gestation were analyzed, and the following results were obtained. 1) The incidence of premature rupture of the membranes (PROM), threatened premature delivery, toxemia and abruption placentae were 40.6, 36.4, 7.8 and 3.0%, respectively. 2) The incidence of chorioamnionitis, retroplacental hematoma (RPH) and placental infarction were 35.1, 18.0, and 13.0%, respectively. 3) Chorioamnionitis of the placenta was found 58.3% in PROM and 26.0% of cases of threatened premature delivery. 4) RPH was found in 70.6% of placenta of abruption and 36.4% of toxemia. 5) Placental infarction was found in 86.4% of toxemia cases and 35.3% of abruption. Each clinical diagnosis was related specifically to each placental finding in cases delivered at 24 to 31 weeks of gestation.

Abortion, Threatened↗
PubMed1987

Modification of the Na+,K+-pump of glial cells within cobalt-induced epileptogenic cortex of rat.

The characteristics of a glial Na+,K+-pump dependent on extracellular K+ within epileptogenic cortex were studied electrophysiologically, biochemically and histochemically in vitro using slices from cobalt-induced epileptogenic cortex of rat. When the extracellular K+ concentration ([K+]o) was varied between 4 and 40 mM, the mean slope of membrane potential plotted against [K+]o was about 57 mV in glia from the normal cortex (tissue A) and about 44 mV in glia from the epileptogenic cortex (tissue B); whereas no significant difference in the resting membrane potential of these tissues was observed. In glia from tissue B, a marked transient hyperpolarization above control level was caused by replacement of elevated [K+]o with the normal medium. Ouabain abolished these phenomena observed in glia from tissue B, but had no effect on the membrane potential during normal [K+]o. Reduction of extracellular Na+, Ca2+ and Cl- did not significantly affect the membrane potential of glia from either tissue. In tissue A, the cells marked by intracellular injection of horseradish peroxidase after intracellular recording were protoplasmic astrocytes; in tissue B, fibrous astrocytes with abnormal processes predominated. K+-dependent stimulation of Na+,K+-ATPase activity of the astrocyte-enriched fraction and its membrane preparation from tissue B was much larger than that from tissue A. A certain amount of the reaction product of K+-pNPPase activity was seen on glial plasma membrane within tissue B but not on that from tissue A. The above findings suggest that a glial Na+,K+-pump within actively firing epileptogenic cortex may be modified to increase in its activity.

Animals↗
PubMed1987

Involvement of pentylenetetrazole in synapsin I phosphorylation associated with calcium influx in synaptosomes from rat cerebral cortex.

To determine precisely how pentylenetetrazole (PTZ) is involved in the biochemical processes at the presynaptic nerve terminal, the effect of PTZ, under various conditions, on the phosphorylation of synapsin I (previously called protein I) was investigated, using 32Pi in synaptosomes from rat cerebral cortex. PTZ markedly stimulated the incorporation of 32P into this protein as determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and autoradiography, but it failed to stimulate protein phosphorylation in Ca2+-free medium containing ethylene glycol bis-(beta-aminoethylether)-N',N'-tetraacetic acid (EGTA). Moreover, the PTZ-stimulated synapsin I phosphorylation was reversed by addition of EGTA sufficient to chelate all external free Ca2+. PTZ also stimulated synaptosomal accumulation of Ca2+. The PTZ-stimulatory effects of both synapsin I phosphorylation and synaptosomal accumulation of Ca2+ were inhibited markedly by tetrodotoxin as well as by cobalt chloride and lanthanum chloride. The calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7, strongly) and N-(6-aminohexyl)-1-naphthalenesulfonamide (W-5, weakly) reduced the PTZ-stimulatory effect on synapsin I phosphorylation by about 75 and 15%, respectively, whereas these antagonists had essentially no effect on PTZ-stimulated synaptosomal accumulation of Ca2+. These results suggest that PTZ causes the influx of Ca2+ into the presynaptic nerve terminal secondary to the elevated Na+ and is consequently involved in the synapsin I phosphorylation step, facilitating the Ca2+/calmodulin-mediated presynaptic event leading to seizure discharge.

Animals↗
PubMed1987

Establishment and characterization of a new murine mammary tumor cell line, BALB/c-MC.

A new murine mammary tumor cell line (BALB/c-MC) was established from a spontaneous mammary tumor in a 17-mo.-old female mouse of the low mammary cancer strain BALB/cHe. The cell line was derived from a papillary adenocarcinoma. In monolayer culture the line exhibits a pavementlike arrangement of cells and forms "domes" or "hemicysts" as the cells become confluent. The cell line rapidly forms tumors when transplanted into young syngeneic BALB/cHe mice. The subcutaneous injection of 10(6) cells resulted in the development of mammary tumors (typical papillary adenocarcinomas) in 33 of 37 (87%) recipients within 2 to 3 mo. after injection. These mammary tumors also metastasize to lung [14 of 33 (42%) of recipients] during this time. The number of chromosomes in this cell line is hyperdiploid (average of 43, range 39 to 44).

Adenocarcinoma, Papillary↗
PubMed1987

Positive inotropic and chronotropic effects of trypsin and some other proteolytic enzymes in the guinea-pig heart.

1 In atrial preparations of the young guinea-pig (body weight 150-250 g), five proteolytic enzymes (trypsin, chymotrypsin, bacterial-Al-proteinase (nagarse), bromelain and kallikrein) produced concentration-dependent positive inotropic and chronotropic effects, while they exerted only minimal effects on the papillary muscle preparations. 2 To characterize the effects, further experiments were conducted in atrial preparations using trypsin. There was a strong tendency for tachyphylaxis: a second exposure to the same concentration of trypsin resulted in considerably smaller positive inotropic and chronotropic effects. The positive inotropic and chronotropic effects of this substance were not affected by propranolol (5 X 10(-7)M). However, an accumulation of cyclic AMP was observed and the positive inotropic and chronotropic effects were potentiated by aminophylline (10(-4)M) in association with an augmentation of the accumulation of cyclic AMP. In preparations partially depolarized with high K+ (22mM) medium (contractions ceased under this condition) trypsin 100 micrograms ml-1 reinstated the contraction. Treatment of the preparation with aprotinin (200 u ml-1) resulted in a strong inhibition of the positive inotropic and chronotropic effects. 3 Islet activating protein (IAP), a specific inhibitor of the 'inhibition specific' guanine nucleotide binding regulatory protein of the adenylate cyclase system, did not produce significant inhibition of the positive inotropic and chronotropic effects of trypsin, whereas it produced a complete inhibition of the negative inotropic and chronotropic effects of carbachol. 4. These results suggest that the positive inotropic and chronotropic effects ofproteolytic enzymes are intimately connected with the proteolytic activities through which adenylate cyclase is activated to produce an accumulation of cyclic AMP within the myocardium. The destruction of the 'inhibition specific' guanine nucleotide regulatory protein of the adenylate cyclase was not substantiated as a mechanism of activation of the adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1987

Transcriptional regulation of bialaphos biosynthesis in Streptomyces hygroscopicus.

A DNA sequence (brpA) which regulates the expression of the genes of the bialaphos biosynthesis pathway (bap) in Streptomyces hygroscopicus was identified and characterized. A newly isolated nonproducing mutant (NP57) had a pleiotropic defect involving at least 6 of the 13 known bap genes; only the step 6 conversion could be detected. NP57 was more sensitive to bialaphos than its parent and had depressed levels of the demethylphosphinothricin acetyltransferase activity (step 10 in the pathway) which confers bialaphos resistance. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of extracts of this mutant showed that it lacked proteins corresponding to steps 5 and 10. NP57 lacked mRNAs for steps 5, 10, and 13. Bialaphos productivity of NP57 was restored by transformation with a plasmid containing a 5.9-kilobase DNA fragment which was adjacent to the structural gene cluster. Subcloning experiments showed that a 1.3-kilobase fragment from this primary clone restored all the defects of NP57. We conclude that brpA can activate the transcription of the bialaphos resistance gene as well as at least six other bap structural genes.

Cloning, Molecular↗