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Biomedical subjects

H Okamura

Publications and source records attributed to H Okamura.

At least 397 records · Page 22Linked to original sources
PubMed1994

Biochemical and immunocytochemical changes induced by intrastriatal 6-hydroxydopamine injection in the rat nigrostriatal dopamine neuron system: evidence for cell death in the substantia nigra.

Biochemical and immunocytochemical changes after unilateral 6-hydroxydopamine (6-OHDA) injection into the striatum were investigated in the rat nigrostriatal dopamine (DA) neuron system. Four weeks after 6-OHDA injection into the striatum, concentrations of DA and its metabolites were specifically decreased in the substantia nigra (SN), as well as in the striatum, ipsilateral to the injection. Immunocytochemistry of tyrosine hydroxylase (TH) revealed a marked decrease in the number of TH-immunoreactive neuronal cell bodies in the SN ipsilateral to the injection; this effect appeared 2 weeks after the injection and remained even 10 months after the injection. Electron microscopic study of these periods demonstrated degenerative neurons in the SN pars compacta, suggesting that the degenerative changes persisted for a long time after a single injection of 6-OHDA into the striatum. The results showed that degeneration of the dopaminergic terminals in the striatum may lead to cell death of the parent cell bodies in the SN and suggest that the striatum may be the initial site in which the neurodegeneration occurs in Parkinson's disease.

Animals↗
PubMed1994

Mucinous adenofibroma of the ovary: case report of the endocrinologic findings.

Endocrine and clinicopathologic findings in a 77-year-old woman with ovarian mucinous adenofibroma of borderline malignancy are reported. The preoperative levels of testosterone, androstenedione, estrone, and estradiol in her peripheral blood were 91 ng/ml, 3.78 ng/ml, 82 pg/ml, and 35 pg/ml, respectively, abnormally high. Those of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were < 0.5 mIU/ml and 12.1 mIU/ml, respectively. Total abdominal hysterectomy and bilateral salpingo-oophorectomy were performed. Pathologic diagnosis of the right ovarian tumor was mucinous adenofibroma of borderline malignancy with hyperthecosis. Postoperatively, the levels of sex steroids and gonadotropin returned to the normal range of a postmenopausal woman. The patient remains well 2 years and 6 months after the operation.

Adenofibroma↗
PubMed1994

Isolation, growth and characteristics of human ovarian surface epithelium.

The ovarian surface epithelium (OSE) is a key tissue in the pathogenesis of ovarian surface epithelial-stromal tumours and ovarian endometriosis, commonly encountered gynaecological diseases. Despite the high incidence of these diseases, experimental in vitro studies of OSE are few and so we used the scraping method with an enzymatic procedure to isolate human OSE and studied its characteristics in vitro. Nineteen normal ovaries were used. After incubation of the ovary for 40 min in collagenase type 1 solution (300 U/ml), the surface cells were removed by gentle scraping with a surgical blade. Cells obtained as a cluster after unit gravity sedimentation with 5% bovine serum albumin in medium 199 were cultured in medium 199 containing 15% fetal bovine serum. The viable cell number in a single ovary was 0.1-2.7 x 10(6). The outgrowth of cells started from a homogeneous population of single cells, and the cell population doubling time was between 7 and 10 days. Confluent monolayers were formed after 13-20 days and subcultured from one to three times. The monolayers mostly had a cobblestone appearance, and fusiform or polygonal cells were also observed. By cytochemistry, immunocytochemistry and scanning and transmission electron microscopy, the cells were shown to have characteristics of mesothelial OSE cells in short-term culture. This experimental approach was efficient in providing cultured human OSE, which can be utilized to investigate pathobiology and carcinogenesis.

Adult↗
PubMed1994

The effect of angiotensin II on utero-placental and umbilical circulation in normotensive pregnant women.

OBJECTIVES: The angiotensin sensitivity test (AST) has been used to identify pregnant women likely to develop pre-eclampsia. The purpose of this study was to evaluate uteroplacental circulation and fetal response to angiotensin II (A-II). METHODS: We studied blood flow velocity waveforms in the uterine and umbilical arteries of 23 normotensive pregnant women before, during and after the AST by Doppler ultrasonography. Fetal well-being was documented with biophysical profiles (BPS). ANOVA and two-way analysis of variation were used to analyze the results. RESULTS: Infusion of A-II to normotensive pregnant women did not affect umbilical artery resistance at 20 or 30 weeks' gestation. Uterine artery resistance and maternal heart rate decreased significantly at 20 weeks' gestation with an AST-induced 10 mmHg or 20 mmHg rise in diastolic blood pressure. The BPS were not altered after the AST. CONCLUSIONS: The AST does not increase vascular resistance in the uterine or umbilical circulation, and may be considered a safe procedure for both the mother and fetus.

Adult↗
PubMed1994

Prevention of preeclampsia with calcium supplementation and vitamin D3 in an antenatal protocol.

OBJECTIVES: Using an angiotensin sensitivity test we carried out a prospective study in an attempt to predict the possible onset of preeclampsia and to prevent it by calcium supplementation (elemental calcium 156 or 312 mg/day per os) and treatment with vitamin D3 (0.5 micrograms/3 day per os). METHOD: We used a study design in which 666 singleton pregnant women were managed with conventional antenatal care and 210 singleton pregnant women were managed with a protocol, together with conventional antenatal care. RESULT: Of the 666 women managed conventionally, 113 (16.9%) developed preeclampsia. However, the incidence of preeclampsia in the 210 women managed on the protocol was lower, at 10.9%. CONCLUSION: Our findings indicate that this protocol for the prediction and prevention of preeclampsia is useful for pregnant women at high risk of developing preeclampsia.

Adult↗
PubMed1994

Organotypic slice culture of the suprachiasmatic nucleus.

To establish an in vitro system which would enable us to observe SCN functions over a long period, we developed a new method to culture SCN tissues by means of a roller tube. Coronal slices containing the SCN were prepared from 5- to 7-day-old rat brains. Slices were maintained for several weeks in plasma clots on coverslips that were immersed in a culture medium within a rotating test tube. In this preparation, vasopressin- and vasoactive intestinal polypeptide-immunoreactive or their mRNA expressing neurons were found in the subdivisions, similar to those found in the SCN in vivo. Moreover, amounts of vasopressin released from the SCN culture into the medium revealed circadian oscillation during the 48-h sampling period. Therefore, SCN in these slice culture conditions in vitro is able to maintain for several weeks not only topographical organization but also functional integrity as a circadian pacemaker.

Animals↗
PubMed1994

Organotypic slice culture of the rat suprachiasmatic nucleus: sustenance of cellular architecture and circadian rhythm.

The suprachiasmatic nucleus of the mammalian brain is thought to be the anatomical locus of circadian rhythms. To examine the functional organization of the suprachiasmatic nucleus in vitro with intact intercellular connections for a prolonged period, we have established an organotypic slice culture system using a roller-tube technique. Brain slices (400 microns in thickness) containing the bilateral suprachiasmatic nuclei, were obtained from newborn rats at four to seven days old and were maintained in vitro for more than three weeks. During this three-week period, the slices flattened to one to three cell layers and two tightly packed neuronal cell-masses (neuronal zones), with diameters of about 1 mm were formed, which were surrounded by a peripheral glial cell-dispersed zone. In the neuronal cell zones, peptides and their messenger RNAs were found cytochemically with characteristic patterns similar to the suprachiasmatic nucleus in the brain. In situ hybridization and immunocytochemistry showed that vasoactive intestinal peptide messenger RNA expressing and vasoactive intestinal peptide-immunoreactive neurons were detected predominantly in the ventrolateral part of the neuronal zones in the suprachiasmatic nucleus slice culture. Vasopressin messenger RNA-expressing and vasopressin-immunoreactive cells were localized in the dorsomedial neuronal zones near the ependymal cell zone. The distribution of cell bodies and fibers containing these neuropeptides and their messenger RNAs in the neuronal zones of suprachiasmatic nucleus organotypic slice culture were similar to that of the suprachiasmatic nucleus in vivo. This suggests that the suprachiasmatic nucleus in these organotypic slice cultures retains the biological characteristics of these cells in vivo as the cells did develop, form compact neuronal masses and did establish connections. To examine the possibility that suprachiasmatic nucleus neurons in slice cultures show a persistent rhythmic activity, we also measured the amount of vasopressin released into the culture medium. Sampling at 4-h intervals combined with enzyme immunoassay revealed that vasopressin concentration in the medium embracing suprachiasmatic nucleus slice cultures fluctuated with a period of approximately 24 h. The present findings suggest that the intranuclear neuronal networks of the suprachiasmatic nucleus are maintained in vitro for a long duration and that organotypic cultures of the suprachiasmatic nucleus produce and release bioactive substances in an oscillating manner. The suprachiasmatic nucleus in slice cultures may be useful for future analysis of circadian rhythms in vitro.

Animals↗
PubMed1994

Baroreceptor-aortic nerve-mediated release of endogenous L-3,4-dihydroxyphenylalanine and its tonic depressor function in the nucleus tractus solitarii of rats.

We have proposed that L-3,4-dihydroxyphenylalanine (L-DOPA) is a neurotransmitter and/or neuromodulator in the central nervous system [Misu Y. and Goshima Y. (1993) Trends pharmac. Sci. 14, 119-123]. This study aimed to explore whether or not endogenous L-DOPA, as a neurotransmitter candidate of the primary baroreceptor afferents, tonically functions to activate depressor neurons in the nucleus tractus solitarii of anesthetized rats. By parallel microdialysis in bilateral nucleus tractus solitarii areas, the basal L-DOPA release was in part inhibited by tetrodotoxin perfusion (1 microM) or Ca2+ deprivation, and was markedly reduced by alpha-methyl-p-tyrosine (200 mg/kg, i.p.), a tyrosine hydroxylase inhibitor. Forty to 100 mM K+ concentration-dependently released L-DOPA. Fifty millimoles K+ repetitively and constantly released L-DOPA. This release was Ca(2+)-dependent. Stimulation of the left aortic nerve (100 Hz, 8 V) repetitively and constantly released L-DOPA and this release was tetrodotoxin-sensitive. Phenylephrine i.v. infused produced L-DOPA release and reflex bradycardia, temporally associated with a rise and subsequent recovery of blood pressure. This release and bradycardia were abolished by denervation of the bilateral carotid sinus and aortic nerves. In addition, L-DOPA methyl ester, a competitive L-DOPA antagonist, when microinjected into depressor sites of the left nucleus tractus solitarii, antagonized depressor responses to mild stimulation (20 Hz, 3 V) of the ipsilateral aortic nerve. This antagonist alone, microinjected bilaterally, elicited a dose-dependent hypertension, which was abolished by alpha-methyl-p-tyrosine. Furthermore, by immunocytochemical analysis seven days after denervation of the left aortic nerve, tyrosine hydroxylase- and L-DOPA-, but not dopamine- and dopamine-beta-hydroxylase-immunoreactivities decreased in the ipsilateral nucleus tractus solitarii and dorsal motor vagus nucleus complex area. In the left ganglion nodosum, denervation decreased staining and number of L-DOPA-immunoreactive cells and staining of tyrosine hydroxylase-immunoreactive cells, but no modification of dopamine-immunoreactive cells was seen. Taken together with previous findings that L-DOPA itself is stereoselectively responsible for cardiovascular control in this nucleus, it is probable that L-DOPA is a neurotransmitter of the primary baroreceptor afferents terminating directly in depressor neurons and/or indirectly in some neurons within a microcircuit, including depressor neurons of the nucleus tractus solitarii. Endogenously released L-DOPA itself tonically functions to activate depressor neurons for regulation of blood pressure in the rat nucleus tractus solitarii.

Animals↗
PubMed1994

Catecholaminergic input to spinally projecting serotonin neurons in the rostral ventromedial medulla oblongata of the rat.

The midline of the rostral ventral medulla (RVM) is the portion in which many serotonin (5-HT) neurons of the nucleus raphe magnus and the rostral nucleus raphe pallidus are located and where dense catecholaminergic (CA) fibers are distributed. In this study, we investigated the connection between spinally projecting 5-HT neurons and CA fibers in the rat RVM by light and electron microscopic immunocytochemistry. First, light microscopic immunocytochemistry using a triple labeling method revealed that the 5-HT-immunoreactive (IR) neuron containing retrograde tracer from the cervical cord was intimately surrounded by tyrosine hydroxylase (TH)-IR fibers. Second, silver-gold intensified TH-IR axon terminals were found to make synaptic contacts with 5-HT-IR neuronal perikarya and dendrites by double labeling immunoelectron microscopy. These morphological findings suggest that spinally projecting 5-HT neurons, presumed to be involved in pain modulation or sympathetic autonomic control, are directly regulated by CA neurons at the level of the RVM.

Animals↗
PubMed1994

Glycolipids isolated from Aplysia kurodai can activate cyclic adenosine 3',5'-monophosphate-dependent protein kinase from rat brain.

Cyclic AMP (cAMP)-dependent protein kinase (cAMP-kinase) partially purified from the membrane fractions of rat brains was stimulated by novel phosphonoglycosphingolipids (glycolipids) derived from the skin and nerve fibers of Aplysia kurodai. Among various glycolipids tested, a major glycolipid from the skin, 3-O-MeGal beta 1-->3GalNAc alpha 1-->3[6'-O-(2-aminoethylphosphonyl)Gal alpha 1-->2](2-aminoethylphosphonyl-->6)Glc beta 1-->4Glc beta 1-->1ceramide (SGL-II), was most potent, giving half-maximal activation at 32.2 microM. Activation of cAMP-kinase was maximal with 250 microM SGL-II using kemptide as substrate. The effect of SGL-II was additive on kinase activity at submaximal concentrations of cAMP. The kinase activity activated with SGL-II was inhibited by the addition of protein kinase inhibitor peptide, a specific peptide inhibitor for cAMP-kinase. Its inhibitory pattern was similar to that for the catalytic subunit. Of the various substrates tested, the glycolipid-stimulated cAMP-kinase could phosphorylate microtubule-associated protein 2, synapsin I, and myelin basic protein but not histone H1 and casein. The regulatory subunit strongly inhibited the activity of purified catalytic subunit of cAMP-kinase. This inhibition was reversed by addition of SGL-II, as observed for cAMP. SGL-II was capable of partially dissociating cAMP-kinase, which was observed by gel filtration column chromatography. However, the binding activity of cAMP to the holoenzyme was not inhibited with SGL-II. These results demonstrate that the glycolipids can directly activate cAMP-kinase in a manner similar, but not identical, to that of cAMP.

Animals↗
PubMed1994

In-vitro enhancement of mouse embryonic development by co-culture with peritoneal macrophages.

The effects of peritoneal macrophages on mouse fertilization and embryonic development in vitro were examined by a co-culture method. In experiment 1, oocytes from F1 strain mice were inseminated and cultured with a monolayer of peritoneal macrophages to determine the effects of the macrophages on fertilization. In experiment 2, 1-cell embryos, fertilized in vivo from either a non-blocking or a blocking strain, were also incubated with peritoneal macrophages to determine whether these cells overcame the developmental arrest. Although the peritoneal macrophages had an adverse effect on fertilization in the F1 strain, embryonic development was significantly improved by the co-culture. This beneficial effect on embryonic development was also observed in the embryos fertilized in vivo from the strain that exhibited a 2-cell block. These results suggest that peritoneal macrophages provide an effective co-culture system for the in-vitro development of mouse embryos.

Animals↗
PubMed1994

Estrogenic induction of NADPH-diaphorase activity in the preoptic neurons containing estrogen receptor immunoreactivity in the female rat.

Nitric oxide and estrogen have been shown to play a critical role in the control of female reproductive function. In order to determine an anatomical relationship between nitric oxide generating neurons and estrogen target neurons, NADPH-diaphorase histochemistry was combined with estrogen receptor immunohistochemistry in the female medial preoptic area. While only a few weakly stained neurons for NADPH-diaphorase were found in ovariectomized control rats, a drastic increase in NADPH-diaphorase activity was observed in the medial preoptic nucleus of estradiol-treated ovariectomized animals. The total number of NADPH-diaphorase neurons in the estradiol-treated group increased three-fold relative to controls, and more than 80% of those neurons contained estrogen receptor-immunoreactivity in their nuclei. Since neuronal NADPH-diaphorase is nitric oxide synthase, the present result suggests that nitric oxide synthase activity can be positively regulated by estradiol in neurons containing estrogen receptor in the female medial preoptic nucleus.

Animals↗
PubMed1994

Induction of substance P-immunoreactivity by estrogen in neurons containing estrogen receptors in the anterovental periventricular nucleus of female but not male rats.

Effects of gonadal steroids on numbers of neurons containing estrogen receptor (ER) and/or substance P (SP) were examined in the anteroventral periventricular nucleus (AVPV) of female and male rats by double-labeling immunohistochemistry employing antibodies specific for ER and SP. Animals were gonadectomized and received subcutaneously either oil alone (Control group), sequential injections of estradiol benzoate and oil (EB + Oil group), or those of EB and progesterone (EB + P group). In the female control rat, a large population of ER-immunoreactive (IR) cells were found clustered throughout the AVPV. They were counted more than 2,000 in total of 4 sections in this nucleus. On the contrary, SP-IR neurons were scarcely observed in the same area of this group. Administration of estrogen to female animals decreased the total number of ER-IR cells to 67% of the control group. In contrast to the supressive effect of estrogen to its own receptor, it induced SP-IR neurons in the AVPV of the female. Approximately 50-80 SP-IR neurons were counted in the 4 sections, and 59% of these neurons expressed ER-IR material in their nuclei. In the female EB + P group, the number of ER-IR neurons also decreased to 79% of the control group. Although the number of SP-IR neurons in this group decreased to 32% of that in the EB + Oil group, a ratio of coexistence of ER-IR material in these neurons increased to 75%. The male control group contained a smaller population of ER-IR cells relative to the female control (1497 vs 2143).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Value of phase-shift gradient-echo MR imaging in the differentiation of pelvic lesions with high signal intensity at T1-weighted imaging.

PURPOSE: To assess the value of phase-shift gradient-echo magnetic resonance (MR) imaging with the fast low-angle shot (FLASH) technique in the differentiation of hemorrhagic tumors and teratomas. MATERIALS AND METHODS: T1- and T2-weighted spin-echo imaging and phase-shift MR imaging were performed in 60 patients. On T1-weighted images, the signal intensity of lesions was compared with that of intraperitoneal fat. Findings at MR imaging were compared with the surgical findings. The diagnostic performance of each pulse sequence was analyzed with receiver operating characteristic curves. RESULTS: Sixty high-signal-intensity lesions were identified in 45 patients at T1-weighted imaging. Hemorrhagic lesions and teratomas had similar signal intensities on both T1- and T2-weighted images. Lesions were detected more decisively with FLASH imaging than with T1- and T2-weighted imaging. CONCLUSIONS: Phase-shift gradient-echo imaging is a readily available method for the differential diagnosis of lesions with high signal intensity at T1-weighted MR imaging.

Adolescent↗
PubMed1994

Neuropeptide participation in canine laryngeal sensory innervation. Immunohistochemistry and retrograde labeling.

We investigated the quantitative participation of calcitonin gene-related peptide (CGRP), substance P (SP), and leu-enkephalin (ENK) in canine laryngeal sensory innervation by immunohistochemistry in combination with retrograde labeling using the recently introduced retrograde tracer cholera toxin subunit B-conjugated gold (CTBG). In the nodose ganglion, neurons labeled from the internal branch of the superior laryngeal nerve with CTBG were investigated immunohistochemically by means of antisera against CGRP, SP, and ENK. The percentages of neurons immunoreactive to each neuropeptide were as follows: CGRP 81.5%, SP 24.5%, and ENK 7.0%. These results suggest that CGRP is the main sensory neurotransmitter in canine laryngeal sensory innervation.

Animals↗
PubMed1994

Colocalization of NADPH-diaphorase and estrogen receptor immunoreactivity in the rat ventromedial hypothalamic nucleus: stimulatory effect of estrogen on NADPH-diaphorase activity.

NADPH-diaphorase (NADPH-d) histochemistry was combined with estrogen receptor (ER) immunohistochemistry in order to study effect of estrogen on NADPH-d activity and establish an anatomical relationship between NADPH-d and ER-immunoreactivity (ir) containing neurons in the ventromedial hypothalamic nucleus (VMN). Gonadectomized female and male rats received either oil (control group) or 10 micrograms of estradiol benzoate (EB) for two successive days and were sacrificed on day 4. While NADPH-d histochemistry stained a specific subpopulation of neurons in the ventrolateral portion of the VMN of all groups, there was a marked sex difference in the effect of EB treatment. EB elevated the number of NADPH-d positive neurons in females but had no significant effect in males. Double-labeling histochemistry revealed that more than 70% of the NADPH-d positive neurons contained ER-ir in the VMN of all groups, with EB-treated females having a significantly higher frequency than all other groups. Since neuronal NADPH-d is nitric oxide synthase (NOS), these results provide anatomical evidence for an association of estrogen with NOS in the rat VMN and suggest that NOS activity can be modulated by estradiol in estrogen sensitive neurons.

Animals↗
PubMed1994

Transcatheter arterial embolization of obstetric and gynaecological bleeding: efficacy and clinical outcome.

32 patients with uncontrollable genital bleeding resulting from postpartum haemorrhage (n = 15) or malignant neoplasms (n = 17) were treated by arterial embolization therapy on an emergency basis. The 15 patients with postpartum haemorrhage responded dramatically to treatment by embolization. Follow-up computed tomography or magnetic resonance studies in 12 cases showed haematomas in the pelvic extraperitoneal space, but most then reduced in size or disappeared spontaneously. In two patients with large haematomas, laparotomy was required. No serious complications developed and normal menstruation resumed in the women who did not undergo hysterectomy. In the 17 patients with malignant neoplasms, bleeding was temporally controlled in all, but recurred in seven and required re-embolization in three. One patient experienced slight numbness of the leg and another had a skin ulcer. All patients underwent subsequent treatment including radiation therapy (n = 10), operation (n = 5) or chemotherapy (n = 2). We conclude that arterial embolization has significant merits in the management of patients with uncontrollable genital bleeding.

Adult↗