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Biomedical subjects

H Okamura

Publications and source records attributed to H Okamura.

At least 721 records · Page 40Linked to original sources
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

Plasminogen activator in rat ovary during the ovulatory process: independence of prostaglandin mediation.

To elucidate the possible roles of increased plasminogen activator (PA) in follicular rupture and to investigate whether prostaglandins participate in ovarian PA synthesis in vivo, enzyme activities were sequentially measured by a method using the chromogenic substrate S-2251 in immature rat ovaries primed with pregnant mare serum gonadotrophin (PMSG) followed by human chorionic gonadotrophin (hCG) either alone or with a concurrent injection of indomethacin. Before hCG injection PA activity was 0.006 +/- 0.006 (S.D.) mumol/1.6 mg ovarian tissue (wet wt) per 30 min: PA activity of a saline-treated group remained at low levels (less than 0.018 +/- 0.003 mumol/l X 6 mg tissue per 30 min). In contrast, PA activity of animals given hCG alone increased after the treatment, reaching a peak value of 0.112 +/- 0.071 mumol/l X 6 mg tissue per 30 min 12h later, before decreasing to 0.023 +/- 0.014 mumol/l X 6 mg tissue per 30 min at 32 h. Contrary to expectations, a dose of indomethacin which completely blocked ovulation had no effect on either the magnitude or the time-course of PA synthesis after hCG administration (P greater than 0.05). These results indicate that prostaglandins are not involved in the preovulatory synthesis of PA induced by hCG in rat ovaries and that PA is not a primary proteolytic enzyme for follicular rupture. It is suggested that PA has possible roles in cumulus detachment and/or proliferation of granulosa cells during the ovulatory process.

Animals↗
PubMed1983

[Morphological and endocrinological study of theca cell tumor during pregnancy].

With a theca cell tumor of the ovary associated with pregnancy, an extremely rare occurrence in a 30 years old primigravida at 15 weeks of gestation, morphological and endocrinological studies were performed. The tumor was composed of cell-nests scattered among a fibromatous structure. The round or polygonal cells are rich in eosinophilic cytoplasm, resembling theca internal cells. The histochemical activity of 3 beta-HSD and G-6-PDH was demonstrated in these cells. They had the ultrastructures characteristic for steroid-producing cells, in some of which immature and mature Reinke crystalloid-like structures were identified. Mature ones were infrequently observed in contrast to the numerous immature ones. It is considered that a few cells might have differentiated into Leydig cells in the course of differentiation into thecomatous cells from ovarian stroma or mesenchyme. Judged from the rapid enlargement in early pregnancy, this tumor may depend on hCG. Serum estradiol was decreased immediately after removal of the tumor even at 15 weeks of gestation. Histochemical, ultrastructural and endocrinological findings suggest that the tumor was secreting mainly estradiol at the time of the operation.

3-Hydroxysteroid Dehydrogenases↗
PubMed1983

[Prolyl hydroxylase activity in rabbit ovary during ovulatory process].

The disruption of connective tissue and dissociation of collagen fibers that occurs in the ovarian follicle during mammalian ovulation is reportedly induced by collagenolytic enzymes. To further analyse the metabolism of ovarian collagen during the ovulatory process, prolyl hydroxylase activity was assayed because the quantity of this enzyme provides some indication of the relative amount of collagen fibrillogenesis in connective tissues. Following the induction of ovulation by hCG, prolyl hydroxylase activity increased in both the ovarian follicle and stroma. The amount of activity reached a maximum of about 300% above the control level at 13hr after hCG, i.e., 1-3hr after the estimated time of ovulation. The pattern of enzyme activity during the ovulatory process was identical in both the follicle and the stroma. The prolyl hydroxylase activity remained at more than 200% above the control level throughout the secretory phase. It is concluded that the rabbit ovarian follicle and stroma contain prolyl hydroxylase activity, and that this enzyme activity increases significantly during the ovulatory process and luteinization.

Animals↗
PubMed1983

Macroglobulinemia and chronic B-cell type lymphocytic leukemia in japan--study of autopsy cases.

Autopsy cases of Waldenström's macroglobulinemia (WM) and chronic lymphocytic leukemia of B-cell type (B-CLL) were examined to determine the geographical distribution and histological characteristics of these diseases in Japan. Both diseases occurred primarily at 50 to 60 years of age with a predominance of males and were distributed throughout Japan with a population slightly lower than that of T-CLL in southwestern Japan. Histologically WM (31 cases) consisted mainly of small cell type malignant lymphoma with plasmacytic differentiation (27 cases) according to the Japanese Classification (LSG) and cytoplasmic immunoglobulins with a monoclonal pattern of immunoglobulin M (IgM) (lambda 12; kappa seven). The bone marrow involvement (27 cases) was follicular, mixed (follicular and diffuse) or diffuse. B-CLL (58 cases) also showed principally a small cell type histology (48 cases) and 16 of the cases showed plasmacytic differentiation as in WM. Cytoplasmic immunoglobulins with a monoclonal pattern were found in 10 (six of IgG, two of IgM, one of IgG and M, and one of IgA). Bone marrow involvement (56 cases) revealed the same histological pattern as WM. According to the growth pattern of the tumor cells in the bone marrow and lymph nodes, both diseases may be categorized as bone marrow-based lymphoma.

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

An immunohistochemical investigation of vasoactive intestinal polypeptide in the colon of patients with Hirschsprung's disease.

The distribution of vasoactive intestinal polypeptide (VIP) in the colon of patients with Hirschsprung's disease was investigated by the peroxidase-antiperoxidase (PAP) immunohistochemical method. Three colonic segments, ganglionic, oligoganglionic and aganglionic, were stained by the unlabeled antibody enzyme method. VIP immunoreactive nerve cell bodies, nerve fibers and nerve endings were distributed throughout the ganglionic and oligoganglionic segments. In contrast, the aganglionic segment contained no VIP nerve endings and the number of fibers was reduced. These differences are thought to be a cause of constriction of the colon in Hirschsprung's disease and VIP neurons are therefore believed to participate in the relaxation of smooth muscle.

Child↗
PubMed1982

Postnatal development of vasoactive intestinal polypeptide immunoreactive amacrine cells in the rat retina.

The ontogenic development of vasoactive intestinal polypeptide (VIP)-immunoreactive amacrine cells in the rat retina was studied using peroxidase-antiperoxidase (PAP) immunohistochemistry. In the rat retina, VIP immunoreactivity appeared entirely in postnatal stage. On the 12th postnatal day, VIP-immunoreactive amacrine cells could be first detected. However, VIP immunoreactivity was very weak and VIP-immunoreactive amacrine cell processes could not be observed at this stage. On the 21st postnatal day, VIP-immunoreactive amacrine cell bodies became more mature and their processes were distinctly observed, resembling their appearance in adult rat retinas. VIP immunoreactivity could be detected in both stratified and diffuse amacrine cells at this stage. The relationship between the first appearance of VIP-immunoreactive amacrine cells and the synaptic formation in the inner plexiform layer is briefly discussed.

Animals↗
PubMed1982

Developmental and periovulatory changes of ovarian norepinephrine in the rat.

Norepinephrine (NE) and dopamine (DA) contained in the rat ovary were determined by high-performance liquid chromatography with electrochemical detection. Concentration of ovarian NE reached adult levels around 5 weeks of age, when the first ovulation occurs. During induction of ovulation, the ovarian NE contents increased slightly during the preovulatory phase, followed by a significant decrease in the postovulatory phase, whereas the turnover of ovarian NE decreased during the preovulatory phase. These results suggest that ovarian noradrenergic nerves were in a somewhat inactivated state during the preovulatory phase. Therefore, ovarian sympathetic nerves are considered to participate in mechanisms of the onset of puberty and ovulation.

Animals↗
PubMed1982

High-level induction of gamma interferon with various mitogens in mice pretreated with Propionibacterium acnes.

Various T-cell mitogens induced high levels of circulating gamma interferon (IFN-gamma) in mice that had been pretreated with Propionibacterium acnes. Administration of lipopolysaccharide, a B-cell mitogen, to these mice also caused pronounced production of IFN-gamma in addition to IFN-alpha and IFN-beta. The enhanced induction was most marked at about 1 week after the pretreatment.

Animals↗
PubMed1982

Neural factors affecting the muscle activity of the human mesotubarium ovarica at ovulatory phase.

Histochemical and in vitro investigations of the autonomic innervation in the human mesotubarium ovarica (MTO) are described here in the course of our studying its physiologic role in the capture of released oocytes at ovulation. The present results imply that the muscle activity of MTO is under the excitatory control of cholinergic nerves and under a reciprocal (predominantly excitatory) control of adrenergic nerves, and that both adrenergic and cholinergic neural factors (at least postsynaptic ones) are related in the enhancement of the muscle activity of MTO around the time of ovulation.

Acetylcholine↗