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Biomedical subjects

Y Okuda

Publications and source records attributed to Y Okuda.

At least 379 records · Page 21Linked to original sources
PubMed1984

Cyclic nucleotides in rat brain during lidocaine infusion.

The concentrations of cyclic 3', 5'-guanosine monophosphate (cGMP) and cyclic 3', 5'-adenosine monophosphate (cAMP) in the cerebellar and cerebral cortex were measured during lidocaine infusion and during bicuculline-induced seizures in rats. The rats were divided into three groups: control, lidocaine (0.74 mg/min) and bicuculline (1.2 mg/kg). The lidocaine group was divided into four stages according to the EEG pattern; desynchronized, synchronized, seizure and recovery. At the desynchronized and synchronized stages, cGMP and cAMP concentrations in both cerebellar and cerebral cortex remained unchanged except for a modest decrease in cerebral cGMP at the desynchronized stage. At the seizure stage, cerebellar cGMP increased from 5.2 +/- 0.9 to 9.2 +/- 1.4 pmol/mg protein and cerebellar cAMP decreased from 8.9 +/- 0.6 to 6.9 +/- 0.6 pmol/mg protein. These changes in concentrations at the seizure stage returned to the control at the recovery stage. During bicuculline-induced seizures, cGMP and cAMP concentrations increased strikingly in both cerebellar and cerebral cortex. These results indicated that lidocaine-induced seizures were accompanied by significant changes in cerebellar cyclic nucleotide concentrations in rats.

Animals↗
PubMed1984

Cerebral energy state and glycolytic metabolism during enflurane anesthesia in the rat.

The effects of enflurane anesthesia on the cerebral cortical energy state and glycolytic metabolism were studied in rats. Twenty-four rats were divided into four groups with increasing concentrations of enflurane in the arterial blood, i.e. control (1.9 +/- 0.3 mg/dl, means +/- s.e.mean), level I (16.1 +/- 1.1 mg/dl), level II (26.0 +/- 1.6 mg/dl), and level III (32.9 +/- 0.9 mg/dl). At level I, high voltage 1-3 Hz slow waves superimposed on low voltage 10-12 Hz waves were predominant, and at levels II and III, spiking activity and burst suppression were recorded in the EEG. The duration of suppression at level III was significantly longer than that at level II. During enflurane anesthesia, there were no significant differences compared with the control group in the cerebral energy state or energy charge. Glycolytic metabolism remained unchanged except for an increase in glucose at levels II and III. Effects of hypocapnia and hypercapnia were examined in an additional 12 rats with an enflurane concentration in the blood similar to that at level II. Irrespective of PaCO2 levels, there were no significant changes in cerebral energy charge and glycolytic metabolites except for a decrease in glucose and an increase in lactate at hypocapnia. It was concluded that there was neither evidence of derangement of energy state nor increased anaerobic metabolism in the cerebral cortex during enflurane anesthesia.

Anesthesia↗
PubMed1983

On the interaction between flavin-adenine rings and between flavin-indole rings by X-ray structural studies.

Two crystal structures of 7,8-dimethylisoalloxazine-10-acetic acid:adenine-9-ylethylamine(1:1)hepatahydrate and 7,8-dimethylisoalloxazine-10-acetic acid:L-tryptophan methylester(1:1)heptahydrate complexes were determined as models for the flavin-adenine and flavin-indole interactions, respectively. In the former complex, both molecules were connected by Hoogsteen-type hydrogen bonds between the pyrimidinoid portion of flavin and the adenine, in addition to the normal stacking of both aromatic rings. On the other hand, parallel stackings and intermolecular vertical spacings less than the normal van der Waals separation distance were observed between the flavin and indole rings of the latter complex, indicative of the pi D-pi A charge-transfer interaction in their ground states. Comparing with the X-ray findings of related complexes, we discussed the interaction modes between flavin and adenine rings and between flavin and indole rings.

Adenine↗
PubMed1983

An ultrastructural study of ovarian perifollicular capillaries in the indomethacin-treated rabbit.

The perifollicular capillaries of the rabbit ovary were observed by light and electron microscopy following administration of human chorionic gonadotropin (hCG) and indomethacin (IM). Fenestrations and interendothelial gaps were not observed at 4, 10, or 12 hours, at which times carbon particles were confined to capillary lumina. By 24 hours, dilated capillaries were noted among granulosa cells and theca. In the theca, interendothelial gaps permeable to carbon particles were observed. At 48 hours, ribosome-rich, newly developed capillaries were noted. Many collagen fibrils were observed in the tunica albuginea and theca externa in hCG/IM-treated rabbits in contrast to those treated with hCG alone. Ovarian prostaglandins normally produced in response to gonadotropins may be responsible for alterations in perifollicular capillaries and degradation of collagen in the follicle wall, changes considered essential for ovulation.

Animals↗
PubMed1983

Ultrastructural study of minute uterine leiomyomas.

Minute uterine leiomyomas, less than 3 mm in diameter, were studied by electron microscopy. In five of 15 cases, morphologically different types of smooth muscle cell were identified. In the central region of leiomyomas, most myoma cells were characterized by filaments sporadically located in the cytoplasm and well-developed organelles. These cells were interpreted as immature smooth muscle cells. In the outer layer of nodules, the cells were a more mature form of smooth muscle cell and resembled normal myometrial cells. The differences suggest that differentiation of the smooth muscle cells occurs early in the growth of uterine leiomyoma.

Adult↗
PubMed1983

Capillary permeability of rabbit ovarian follicles prior to ovulation.

Ultrastructurally, three possible pathways of capillary permeability were observed during the ovulatory process in rabbit ovarian follicles treated with human chorionic gonadotrophin: namely, pinocytotic vesicles, fenestrations, and interendothelial gaps. The increased permeability of perifollicular capillaries just prior to ovulation was confirmed as being primarily due to the formation of gaps, using carbon particles as a tracer.

Animals↗
PubMed1982

In vitro tuberculin reactivity of lymphocytes from patients with tuberculous pleurisy.

Mononuclear cells in pleural fluid from patients with tuberculous pleurisy were predominantly T cells. Responsiveness of pleural fluid T cells to purified protein derivative of tuberculin were studied by the assay of cell proliferation and production of lymphocyte mitogenic factor by the stimulation with purified protein derivative. Peripheral blood lymphocytes were also studied from patients and tuberculin-positive healthy controls. The order of responsiveness was as follows: pleural fluid lymphocytes greater than peripheral blood lymphocytes of patients without effusion = peripheral blood lymphocytes of healthy controls greater than peripheral blood lymphocytes of patients with effusion. The poor response of peripheral blood lymphocytes from pleurisy patients were recovered by the elimination of adherent cells in peripheral blood lymphocytes to the level of the response of peripheral blood lymphocytes from healthy controls. T cells purified from pleural fluid mononuclear cells responded more than those from peripheral blood. These results suggested that in the pleurisy patients purified protein derivative-reactive T cells in peripheral blood did not decrease in activity, but were depressed by suppressor cells, and further suggested that highly purified protein derivative-reactive T cells were accumulated in the pleural fluid.

Adult↗
PubMed1982

[An ultrastructural study of capillary permeability of rabbit ovarian follicles using horseradish peroxidase as a tracer (author's transl)].

In the previous study, using carbon tracer, we reported the ultrastructural evidences which suggested the increased capillary permeability of preovulatory rabbit ovarian follicles. In the present study, another tracer, horseradish peroxidase (HRP 50 A in diameter, mw. 40,000), being smaller than carbon particle, was used to examine the permeability of perifollicular capillaries. HRP left capillaries and appeared in the follicular cavity immediately after the injection into aorta, through all stages of follicular development. In the capillaries, the narrow interendothelial clefts (about 100-200 A in width) were observed through preovulatory stages. Fenestrations were noted at 3,4,6 hours after the hCG injection, and interendothelial gaps (about 1,000-10,000 A in width) were seen at 10, 12 hours. HRP passed through these structures and infiltrated the capillary basal lamina and the basal lamina of the follicle and went through the intercellular spaces between granulosa cells. Therefore, the increased permeability of perifollicular capillaries, just prior to ovulation, were not so obvious as when carbon particles were used. On the other hand, carbon particles, injected via marginal ear vein, were incorporated in the endothelial vesicles 15 min. after its administration and retained beneath the basal lamina outside the follicle within 60 min. These observations indicated that "blood follicle barrier" consisting of capillary endothelium, basal lamina, basal lamina of the follicle and granulosa layer played an inhibitory role to large molecules but not to small molecules.

Animals↗
PubMed1982

[Scanning electron microscopic observations of microcorrosion casts for non pregnant rat uterine vascular architecture (author's transl)].

Uterine vascular architecture through estrus cycle of the rat was investigated by the microcorrosion casting/scanning electron microscopy method. Arterial system in the uterine horn was divided into two types, one of which consisted of circumferential artery with its branches extending to both side walls and an antimesometrial wall. The other system consisted of arterioles which turned into the vascular congromerate in the mesometrial triangle and then distributed their branches to the mesometrial wall. Both of two kinds of arterioles, the terminal arteriole in the myoendometrium and the larger arteriole composing the vascular congromerate, showed the circular impressions around them. Arteriovenous anastomosis was not observed in the uterus. During proestrus and estrus, uterine blood vessels were lengthened except for arterioles in the vascular congromerate, and the subepitherial capillary network became to be filled completely with resin and showed the signs of leakage. These changes reached the maximum in estrus, then subsided during the later part of the cycle. These observations suggest that different types of arterioles in the uterus have their own sphinctors, and maximum enlargement of the uterine vascular bed occurs in estrus concomitantly with increased capillary permeability.

Animals↗
PubMed1981

Progesterone-induced smooth muscle-like cells in the subperitoneal nodules produced by estrogen. Experimental approach to leiomyomatosis peritonealis disseminata.

In order to examine the pathogenesis and histogenesis of leiomyomatosis peritonealis disseminata (LPD), guinea pigs were treated with various doses of estradiol benzoate (E) (40, 80, 100, and 200 microgram/day, three times a week, by intramuscular injection). After treatment for 3 months, each dose of E produced lesions simulating the disseminated pattern of LPD. Ultrastructurally, the nodules were considered to be composed of cells resembling those of fibroblast. In guinea pigs, pretreatment with estradiol benzoate (100 microgram/day, three times a week intramuscularly for 3 months followed by combination treatment with E and progesterone (P) (0.5 and 1.0 mg/day, once a week, intramuscularly) for 1 to 3 months produced nodules similar to those with estrogen alone. Ultrastructurally, these nodules were composed of cells resembling smooth muscle and decidual cells. According to these results, we conjectured that estrogen differentiates and proliferates cells with the features of fibroblast-like cells from the subcoelomic totipotential mesenchyme, and these cells are differentiated into smooth muscle-like cells and decidua-like cells under the influence of both estrogen and progesterone, resulting in the production of multiple subperitoneal nodules.

Abdominal Neoplasms↗
PubMed1981

A study on the relationship between the prognosis of chronic active hepatitis and the HBV associated antigen/antibody systems.

The relationship between the prognosis of the disease based on liver histology and HB virus (HBV) associated antigen/antibody systems was investigated in twenty seven patients with chronic active hepatitis (CAH). These patients were followed up over extended periods with mean duration of 44.3 months. On initial liver biopsy five of twelve patients with CAH with spotty or focal necrosis were HBs antigen (HBsAg) positive, as were also five of six patients with sublobular necrosis and six of nine patients with lobular disorganization. Most of the HBsAg negative patients were anti-HBs or anti-HBc positive: HBV associated antigen or antibody was completely undetectable in only three of the twenty seven patients. There was no difference in the frequency of progression to liver cirrhosis (LC) between the sixteen HBsAg positive and the eleven HBsAg negative patients with CAH. On the other hand, progression to LC occurred in only one of seven HBe antigen (HBeAg) negative patients, compared to four of nine HBeAg positive patients, who were HbsAg positive. There were four patients who were HBeAg positive initially but then became HBeAg negative in the course of observation. LC developed in two of these four patients. These results suggest that in HBsAg positive patients with CAH the presence or absence of HBeAg and the variation in its level can provide useful indicators of the prognosis of the disease.

Adolescent↗
PubMed1981

The adrenergic nerve supply to bovine ovarian follicles.

To obtain more exact knowledge of the adrenergic innervation around ovarian follicles at various stages, a combination of fluorescence and light microscopic observations of the same specimen was applied to the bovine ovary in the breeding season. We found no fluorescent nerve fibers in the membrana granulosa at any stages of follicular development. The sparse nerve fibers found in the theca interna of Graafian follicles were apparently those accompanying blood vessels, and such were considered not to play a significant role in the vasomotor control of follicular blood flow. The fluorescent fibers in the theca externa increased in density and intensity in the course of follicular development. This increase appears to coincide with the increasing contractility of the follicular wall around the time of ovulation.

Animals↗