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Biomedical subjects

N Hashimoto

Publications and source records attributed to N Hashimoto.

At least 631 records · Page 35Linked to original sources
PubMed1986

Transsphenoidal extracapsular approach to pituitary tumors.

Two years' experience with an extracapsular transsphenoidal approach to pituitary adenomas is presented. Some pituitary tumors contain an inordinate amount of connective tissue that often makes transsphenoidal resection difficult. By opening the tumor capsule and adjacent arachnoid membrane, such tumors with suprasellar extension can be safely removed. In some cases of functioning adenoma, resection of the diaphragma sellae and adjacent arachnoid membrane results in hormonal control. Among 62 cases of transsphenoidal surgery for pituitary adenomas, eight cases required this procedure. The surgical procedure is described and the cases are summarized. The indication and limitations of this procedure are discussed.

Adenoma↗
PubMed1986

Cell cycle dynamics of maturation-promoting factor during mouse oocyte maturation.

The changes in activity of a cytoplasmic maturation-promoting factor (MPF), capable of inducing resumption of meiosis when injected into starfish oocytes, were examined during mouse oocyte maturation. MPF appeared first at the time of germinal vesicle breakdown (GVBD), and its activity fluctuated along with the meiotic cycle: it reached a peak at the first metaphase and disappeared at the first polar body emission. Then MPF reappeared and reached a peak again at the second metaphase. Thus, a good correlation was found between MPF activity and meiotic metaphase. When mouse oocytes were treated with cytochalasin D, metaphase chromosomes and meiotic spindles were maintained after the first metaphase. In such a case, MPF activity remained at an elevated level after the first peak. Addition of cycloheximide to these cytochalasin-treated oocytes caused diminution of MPF activity, followed by chromosome movement, decondensation and formation of nucleus-like structures. Thus, it is likely that disappearance of MPF activity induces transition from metaphase to the subsequent processes. Further, detailed observation of chromosomes revealed that only the monovalent chromosomes were competent to decondense in response to the disappearance of MPF. Therefore, it was suggested that dissociation of synapsis is necessary for the decondensation of chromosomes.

Animals↗
PubMed1986

[CT findings of growth hormone secreting pituitary adenomas].

The value of high-resolution computed tomography (CT) in the diagnosis of pituitary adenoma has recently been stressed, especially of the coronal view with contrast enhancement. Analysis of the CT scans of 33 growth hormone (GH) secreting pituitary adenomas was done (11 cases of microadenomas, 7 cases of intrasellar adenomas and 15 cases of macroadenomas with suprasellar extension). In macroadenomas, the density was high in five cases, high with isodense portion in two cases, mixed in four cases, isodense in three cases, and isodense and low dense in one case. Six adenomas showed homogeneous density and nine were heterogeneous. After contrast enhancement, two cases showed marked enhancement, ten cases mild and three cases ring enhancement. Margin of adenoma was smooth in nine cases and irregular in six. Among seven cases of intrasellar adenoma one accompanied primary empty sella. In microadenomas ten of eleven cases had hypodense mass inside the normally enhanced pituitary gland. The margin was ill-defined in seven cases and well-defined in three. Eight cases had pituitary height 7 mm or more. Upper surface of the pituitary gland was convex upward in five cases, flat in four and concave in two. Deviation of pituitary stalk was found in seven cases. Bony changes of sellar floor were recognized in three cases. There was a tendency that serum GH level increased with the increment of the size of adenoma. Serum GH levels in adenomas with ring enhancement were lower than those in the homogeneously enhanced adenomas of similar size. One case with marked enhancement showed the highest GH level among all adenomas of the presented series.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1986

Early changes of experimentally induced cerebral aneurysms in rats. Light-microscopic study.

The changes of the anterior cerebral artery/olfactory artery junction, one of the favorite sites of aneurysm formation, in rats treated with unilateral ligation of the common carotid artery and renal hypertension were investigated by light microscopy. The initial changes of aneurysm occurred not at the apex itself, but on the distal side of the major branch adjacent to the apex, at the intimal pad and the neighboring distal portion. Here the internal elastic lamina showed various degenerative changes and disappearance. The neighboring distal portion adjacent to the intimal pad showed a shallow depression associated with a thinning of the media due to a decrease of medial smooth muscle cells in number even in some control animals. Such degenerative changes of the internal elastic lamina and medial smooth muscle cells caused by hemodynamic stress due to branching structure, including intimal pads, augmented by the experimental treatment, are supposed to be the basis for aneurysm formation.

Animals↗
PubMed1985

Epimerization kinetics of moxalactam, its derivatives, and carbenicillin in aqueous solution.

The mechanism of the epimerization of moxalactam was studied by measuring the rate of epimerization after deuteration of the C-7 side-chain chiral carbon, introduction of different substituents on the side chain, and variation of the ring system. Deuteration slowed the epimerization rate considerably. The rate was also influenced by the choice of the ring system and the substituent on the C-7 side-chain chiral carbon. When the penicillin ring system with the 2-carboxy-2-phenyl-acetamide was studied, the epimerization rate decreased indicating that the same ring system needed to be used throughout the epimerization studies. Thus, experiments were conducted with different substituents replacing the phenolic group at the C-7 side-chain chiral carbon of moxalactam. The epimerization rate decreased in the substituent order thienyl, phenyl, 4-hydroxyphenyl, the ionized form of 4-hydroxyphenyl, and ethyl. These results showed that dehydrogenation of the chiral carbon seems to be the rate-determining step and that the stronger the electron-donating effect of the substituent, the slower the epimerization rate becomes.

Carbenicillin↗
PubMed1985

Insulin-sensitive phosphodiesterase and insulin receptor binding in fat cells from spontaneously obese rats.

The effects of insulin on insulin-sensitive phosphodiesterase were investigated in fat cells from rats aged 4, 8 and 16 weeks. The enzyme activities in rats aged 4 and 8 weeks higher at 0.1-30 nmol/l insulin concentrations than in rats aged 16 weeks, and half-maximum stimulations were obtained at 0.08 nmol/l in rats aged 4 weeks, at 0.15 nmol/l in rats aged 8 weeks and at 0.22 nmol/l in rats aged 16 weeks. Specific binding of insulin in fat cells from rats aged 4, 8 and 16 weeks was 3.3%, 5.0% and 11.6%/2 X 10(5) cells, respectively. Scatchard analysis indicated that increased insulin binding in fat cells from rats aged 16 weeks was due mainly to an increase of binding affinity. These results suggest that impairment of the phosphodiesterase activation system in fat cells from spontaneously obese rats is predominantly due to post-receptor defects.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Pharmacokinetics of famotidine, a new H2-receptor antagonist, in relation to renal function.

The pharmacokinetics of a new, potent H2-receptor antagonist, famotidine, 20 mg i.v. was studied in 7 subjects with normal renal function and in 24 patients with varying degrees of renal impairment. The volume of distribution at steady state was 1.141/kg in normal subjects and was not altered in renal failure. The half-life of elimination was 2.59 h in normal subjects and was unchanged in mild renal failure (creatinine clearance, CLCR 90-60 ml/min/1.48 m2) but was increased to 4.72 h in moderate renal failure (CLCR 60-30 ml/min/1.48 m2), and to 12.07 h in severe renal failure (CLCR below 30 ml/min/1.48 m2). The cumulative urinary excretion and renal clearance of famotidine were correspondingly reduced in patients with impaired kidney function. In normal subjects and in patients with mild to moderate renal failure, about 70% of famotidine was excreted through the kidney, mainly by tubular secretion. In patients with a CLCR above 60 ml/min/1.48 m2 the normal daily dose of famotidine can be employed, but in those with a CLCR between 60 and 30 ml/min/1.48 m2 the dose should be reduced by half, and in patients with a CLCR below 30 ml/min/1.48 m2 a reduction by three quarters of the normal dose is recommended.

Adult↗
PubMed1985

Cell fusion by haemorrhagic fever with renal syndrome (HFRS) viruses and its application for titration of virus infectivity and neutralizing antibody.

Haemorrhagic fever with renal syndrome viruses, are members of the family Bunyaviridae. They cause cell to cell fusion from within under acidic conditions. This phenomenon was found to occur under a pH range of between 4.9 to 6.3 for all the viruses examined. The pH range which causes cell fusion was similar to that reported for the La Crosse virus of the Bunyaviridae, hence indicating that this property is a common biological characteristic among this family of viruses. Titration of virus infectivity and neutralizing antibody was done by counting the number of fused cell foci produced in infected Vero cell monolayers after low pH treatment. This method was simpler and more rapid than the ordinary plaque formation method or that of counting infected cell foci by IFA or immunoenzyme assay. In addition, this method may also be applicable in the detection of other enveloped viruses which do not cause a typical cytopathic effect.

Animals↗
PubMed1985

Getah virus in several species of mosquitoes.

Vector competence of Aedes (Ae.) vexans nipponii (nip.) and Culex (Cx) tritaeniorhynchus for Getah virus was compared after incubation at 28 degrees C and 20 degrees C. Marked differences existed between Ae. vexans nip. strains Sapporo and Cx tritaeniorhynchus strain Kyoto in infection and transmission rates following ingestion of blood meals containing several concentrations of Getah virus. Simultaneous comparison of infectivity also revealed that infection rates of Ae. vexans nip. strains Sapporo (74%) and Shizunai (68%) were higher than those of Cx tritaeniorhynchus strain Kyoto (44%). No significant differences were seen in infection rates between three strains of Cx tritaeniorhynchus or between two strains of Ae. vexans nip. Getah virus propagated and was transmitted in Ae. vexans nip. as rapidly at 20 degrees C as at 28 degrees C. Following seven days' incubation both at 20 degrees C and 28 degrees C, Ae. vexans nip. was capable of transmitting the virus. 14 days' incubation at 20 degrees C were needed for Cx tritaeniorhynchus to acquire the same capability. Ae. japonicus, Ae. aegypti, Ae. albopictus, Cx pipens pallens, Armigeres subalbatus and Tripteroides bambusa were also susceptible to Getah virus infection.

Aedes↗
PubMed1985

Histologic study of normal rat brain tissue after neodymium-yttrium aluminum garnet laser irradiation. I. Cerebral hemisphere.

We report a histologic study of normal rat brain tissue after neodymium-yttrium aluminum garnet laser irradiation. Morphological changes occurred at a maximum depth of 5 mm after 60-W, 1-second exposure, at a 2-mm distance between the optical fiber tip and the brain surface. Polymorphonuclear leukocyte infiltration into the irradiated area was observed 48 hours after irradiation. After 72 hours, macrophages and fibroblasts appeared; their number increased thereafter. At 1 month, tissue defects attributable to neodymium-yttrium aluminum garnet laser irradiation were small. Gliotic changes were rarely seen. We conclude that 60-W irradiation is harmful to young rats but not to adult rats.

Animals↗