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Biomedical subjects

H Okamura

Publications and source records attributed to H Okamura.

At least 775 records · Page 43Linked to original sources
PubMed1980

[An ultrastructural study of capillary permeability of rabbit ovarian follicles during ovulation using carbon tracer (author's transl)].

The observations that perifollicular capillaries of the ovary become engorged with prominent edema in the theca interna and externa around the time of ovulation, suggest a preovulatory increase in permeability of perifollicular capillaries. In previous study, we reported ultrastructural evidences which suggested the increased permeability of perifollicular capillaries just prior to ovulation. In this study, we further examined the perifollicular capillaries of rabbit ovary by using carbon particles as a tracer at various time intervals after the hCG injection for induction of ovulation. Pinocytotic vesicles exhibited no significant changes in size, number and distribution through all preovulatory stages. Carbon particles were not taken into them. Fenestrations were observed at 0,3,4,6 hrs after the hCG injection, most frequently at 4 hrs, but no carbon particles could penetrate them. Intercellular gaps between two adjacent endothelial cells began to be observed at 10 hrs after the hCG injection. Carbon particles passed through these gaps with staying inside the basement membrane (so-called intramural leaking). These observations indicated that the increased permeability of the perifollicular capillaries, just before ovulation, were due to intercellular gaps.

Animals↗
PubMed1980

Physiological study of the human mesotubarium ovarica.

The human mesotubarium ovarica has been shown to contain bundles of smooth muscle cells. Its contractility at various phases of the menstrual cycle was studied in vitro in 51 tissue strips obtained at laparotomy. The strips obtained at the ovulatory phase showed the greatest spontaneous contractile activity as well as the greatest contractile response to norepinephrine, acetylcholine, and prostaglandin F2 alpha. This corresponds to the increased contractility of the ovary at this phase of the cycle. It is suggested that these contractile actions may, under the influence of chemical transmitters, play a role in ovum pick-up by the tubal fimbria at ovulation.

Acetylcholine↗
PubMed1978

Cerebral ventriculitis associated with Achromobacter xylosoxidans.

Six patients in the neurosurgical ward of Fukushima Medical College Hospital suffering from ventriculitis due to Achromobacter xylosoxidans infection had undergone craniotomy or cranial trepanation before the infection. The strains of A. xylosoxidans isolated from the patients were resistant to streptomycin, ampicillin, cephaloridine, gentamicin, and colistin. They were also resistant to chlorhexidine digluconate (Hibitane) in a concentration of 2%. When a study of the chlorhexidine used in the hospital was carried out four strains of A. xylosoxidans were isolated from 20 containers of chlorhexidine solution in the surgical ward but not from those in the operating theatre.

Alcaligenes↗
PubMed1978

[Flow of molten metal in denture base in horizontal centrifugal casting procedure. (Part 2) Flow, inflow volume and casting time of molten metal passing through several sprues into model denture plate mold (author's transl)].

Two types of spruing methods were used in the casting of the denture type model pattern (thickness, 0.43 mm). Flow of molten metal in the mold was filmed by the improved system of Part 1. When three sprues were attached to the pattern vertically, molten metal passed through each sprue gate flowed being affected by the direction of gravity and revolution of casting machine, and gathered at the lower part of the mold. Next molten metal filled the mold from the lower part to the upper part. In this spruing type, molten metal turned its direction of flow several times. At the middle stage of casting, the inflow volume per unit time (inflow rate), v (mm3/10-2)s)was evaluated as v = 12.36 + 5.16A-0.16 A2 (A: total cross-sectional areas of sprues). The inflow rate increased with increase of the area of the sprues, but it saturated. When the main sprue and the subsprues were attached at the posterior border, the molten metal filled the mold from the lower part to the upper part quietly. In this spruing type, the casting mold was set facing its sprue gates downwards. The inflow rate at the middle stage of casting was evaluated as v = 21.05 + 1.79 C (C: the cross-sectional area of the main sprue). The inflow rate increased linearly with increase of the area of the main sprue.

Dental Casting Technique↗
PubMed1977

Tyramine oxidase and regulation of arylsulfatase synthesis in Klebsiella aerogenes.

The participation of tyramine oxidase in the regulation of arylsulfatase synthesis in Klebsiella aerogenes was studied. Arylsulfatase was synthesized when this organism was grown with methionine or taurine as the sulfur source (nonrepressing conditions) and was repressed by inorganic sulfate or cysteine; this repression was relieved by tyramine and related compounds (derepressing conditions). Under nonrepressing conditions, arylsulfatase synthesis was not regulated by tyramine oxidase synthesis. However, derepression of arylsulfatase and induction of tyramine oxidase synthesis by tyramine were both antagonized by glucose and other carbohydrate compounds. The derepressed synthesis of arylsulfatase, like that of tyramine oxidase, was released from catabolite repression by use of tyramine as the sole source of nitrogen. A mutant strain that exhibits constitutive synthesis of glutamine synthetase and high levels of histidase when grown in glucose-ammonium medium was subject to the catabolite repression of both tyramine oxidase and arylsulfatase syntheses. Mutants in which repression of arylsulfatase could not be relieved by tyramine could not utilize tyramine as the sole source of nitrogen and were defective in the gene for tyramine oxidase.

Amino Acid Oxidoreductases↗
PubMed1977

Genetic control of arylsulfatase synthesis in Klebsiella aerogenes.

It was shown that at least four genes are specifically responsible for arylsulfatase synthesis in Klebsiella aerogenes. Mutations at chromosome site atsA result in enzymatically inactive arylsulfatase. Mutants showing constitutive synthesis of arylsulfatase (atsR) were isolated by using inorganic sulfate or cysteine as the sulfur source. Another mutation in which repression of arylsulfatase by inorganic sulfate or cysteine could not be relieved by tyramine was determined by genetic analysis to be on the tyramine oxidase gene (tyn). This site was distinguished from the atsC mutation site, which is probably concerned with the action or synthesis of corepressors of arylsulfatase synthesis. Genetic analysis with transducing phage PW52 showed that the order of mutation sites was atsC-atsR-atsA-tynA-tynB. On the basis of these results and previous physiological findings, we propose a new model for regulation of arylsulfatase synthesis.

Amino Acid Oxidoreductases↗
PubMed1977

A morphological and physiological study of mesotubarium ovarica in humans.

In order to clarify the mechanisms by which the egg is transported from the ruptured follicle into the fimbrial end of the Fallopian tube in the human being, the mesotubarium ovarica (MTO), the unique anatomical structure which connects the tubal fimbriae and the ovary, was studied in seven human adnexal specimens histochemically and electron microscopically. The results demonstrated clearly the presence of smooth muscle cells in the MTO, and failed to demonstrate the presence of cilia in the lining epithelial cells of the MTO. Based on these morphological results, contractility of the MTO was studied in vitro by using a muscle chamber and a pressure transducer with 26 human adnexal specimens. Spontaneous contractile activites of regular frequency and moderate intensity were observed in the MTOs of all specimens examined. A possible role of the MTO in the mechanisms of ovum pickup at the time of ovulation is discussed.

Adult↗
PubMed1977

Scanning electron microscopy of human female reproductive tract and amniotic fluid cells.

Scanning electron microscopy was used to examine surface ultrastructural characteristics of cells of the epithelium of female reproductive tract, cervical mucus, and amniotic fluid cells. The female epithelium undergoes hormone-dependent cyclical morphological alterations in cell shape, apical microvilli, ciliation, and secretory patterns. The frequency distribution of ciliated cells varies in different parts of the female reproductive tract and different segments of the same organ. In the endocervix, a few ciliated cells are randomly distributed. The density of ciliated cells is variable in several areas of the endometrium. The sparse distribution of ciliated cells in the central portion of the uterine wall may indicate a possible implantation site. According to surface ultrastructure of cells, three segments are noted in the uterotubal junction: cornual endometrium, interstitial tubal epithelium, and transitional area. The vaginal epithelium is made of flat polygonal cells with interdigitating borders and a fine interlacing network of microridges. After the menopause, the microridge pattern and distinct cell borders are lost or severely modified. Two types of fibrous structures can be found in cervical mucus: a) microfibrils that vary in diameter from 500 to 1,500 A and from bundles or networks, and b) long, thick fibers that vary in diameter from 0.5 to 5 micrometer run parallel to each other, and appear to be made up of microfibrils. Amniotic fluid cells, derived from amniotic epithelium and fetal ectoderm, consist of non-nucleated and nucleated cells with extensive microplicae.

Amniotic Fluid↗
PubMed1977

A morphologic study of mesotubarium ovarica in the human.

In order to clarify the mechanisms by which the egg is transported from the ruptured follicle into the fimbrial end of the fallopian tube in the human, the mesotubarium ovarica (MTO), the unique anatomic structure which connects the tubal fimbriae and the ovary, was studied in seven human adnexal specimens histochemically and electronmicroscopically. The results demonstrated clearly the presence of smooth muscle cells in the MTO, and failed to demonstrate the presence of cilia in the lining epithelial cells of the MTO. A possible role of the MTO in the mechanisms of ovum pick-up at the time of ovulation is discussed.

Adult↗