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Biomedical subjects

K Ishimura

Publications and source records attributed to K Ishimura.

At least 55 records · Page 3Linked to original sources
PubMed1996

Increase in portal blood interleukin-6 soon after the commencement of digestive surgery.

To determine whether cytokines produced in the operative field during digestive surgery selectively spill over into the portal blood, the changes in interleukin-6 (IL-6) levels in portal and peripheral venous blood were assayed at several points in time from the commencement of surgery until 14 days later, in 11 patients. Similar changes in the IL-6 levels were observed in the portal and peripheral blood samples; however, the IL-6 levels in the portal blood reached a maximum 6-12h after the commencement of surgery, being earlier than in the peripheral venous blood. In fact, between 3 and 12h after the commencement of surgery, the IL-6 levels were higher in the portal blood by 33-81 pg/ml. By 24h or more after the commencement of surgery, the IL-6 levels did not differ significantly in the two types of blood samples. Moreover, the C-reactive protein levels 2 days after surgery were even more closely correlated to the maximum IL-6 levels in the portal blood than to those in the peripheral venous blood. These results suggest that IL-6 produced during intra-abdominal digestive surgery initially enters the portal blood, being trapped by IL-6 receptors in the liver, where it may regulate the synthesis of acute-phase proteins as a hepatocyte-stimulating factor.

Adult↗
PubMed1996

Immunocytochemical localization of 5 alpha-reductase type 1 in the prostate of normal and castrated rats.

We immunohistochemically studied the localization of 5 alpha-reductase type 1 in combination with androgen receptor (AR) expression in individual lobes of the prostates of intact and castrated rats. In the normal rat prostate, 5 alpha-reductase was localized in the cytoplasm of most epithelial cells in the ventral, dorsal, and lateral type 1 (L1) lobes. Epithelial cells of lateral type 2 (L2) lobes were negative for 5 alpha-reductase. AR was present in the nuclei of all epithelial and stromal cells throughout the prostate. The number of 5 alpha-reductase-immunoreactive cells rapidly decreased in the ventral and L1 lobes after castration, whereas many positive cells remained in the dorsal lobe even at 4 weeks after castration. AR immunostaining was lost in the ventral, dorsal, and L1 lobes at 1 week after castration, but remained in the L2 lobe of 4-week-castrated rats. Electron microscopic immunocytochemistry showed that 5 alpha-reductase was exclusively localized in the rough endoplasmic reticulum membranes and that there were no distinct structural differences between the positively and negatively stained epithelial cells. These findings suggested that the expression of 5 alpha-reductase type 1 in the epithelial cell is heterogeneous within and among the individual lobes of the rat prostate, and does not correspond to AR expression.

Animals↗
PubMed1996

Steroid 5 alpha-reductase type 1 immunolocalized in the anterior pituitary of intact and castrated male rats.

The localization of 5 alpha-reductase was immunohistochemically studied in the anterior pituitary of male rats, using a polyclonal antibody against 5 alpha-reductase rat type 1. The immunoreactive cells were concentrated in the central region and on the border of the intermediate lobe in the anterior pituitary, but not in the intermediate or posterior lobe. The immunoreaction was located mostly in the cytoplasm and occasionally in the cell nuclei. The immunoreactive cells showed alterations in size and number and in the intensity of the immunoreaction after gonadectomy. One week after castration, the cells became larger and the immunoreactivity increased. Two weeks after castration, the number of immunoreactive cells increased. Double immunostaining using anti-luteinizing hormone beta-subunit or anti-follicle stimulating hormone beta-subunit antibody revealed that most of the cells containing 5 alpha-reductase were gonadotrophs. Electron microscopically, the immunoreactive cells showed lamelliform rough endoplasmic reticulum and a depletion of secretory granules 1 week after castration. One week later, the rough endoplasmic reticulum was developed and dilated and the number of secretory granules increased. These results suggest that 5 alpha-reductase is located in the gonadotrophs of rat anterior pituitary and that it is involved in the feedback regulation of gonadotropin secretion by androgens.

Amino Acid Sequence↗
PubMed1996

Protective effects of antithrombin III supplementation on warm ischemia and reperfusion injury in rat liver.

The effect of antithrombin III (AT III) supplementation on energy status, microcirculation, cytoprotection, and prostacyclin (PGI2) production during and after a period of warm ischemia of the rat liver was investigated. AT III supplementation (250 units/kg) stimulate prostaglandin I2 (PGI2) production from 1 hour after administration, with maximal production observed at 3 hours. Ischemia was induced by occluding the hepatoduodenal ligament for 30 minutes, and experiments were continued for 60 minutes after reperfusion. The rats received AT III (250 units/kg IC) 30 minutes before induction of liver ischemia (AT III group). In the AT III group, recovery of the beta-ATP/inorganic phosphate ratio measured by 31P nuclear magnetic resonance showed significant improvement (p < 0.01), and the recovery of tissue blood flow markedly improved (p < 0.01) compared to the saline-treated group (control group). Leakages of aspartame aminotransferase, alanine aminotransferase, and lactate dehydrogenase were mitigated in the AT III group (p < 0. 05). Ultrastructural alterations of sinusoidal endothelial cells were markedly reduced in the AT III group. The PGI2 level at the end of reperfusion was significantly elevated (p < 0.01) in the AT III group compared to the control group. The results of this study indicated that pretreatment with AT III significantly improved the energy status and microcirculation, as well as histologic damage, after liver ischemia and reperfusion. One of the fundamental effects of AT III might be mediated through the production of prostacyclin.

6-Ketoprostaglandin F1 alpha↗
PubMed1996

Arachidonate 12-lipoxygenase in porcine anterior pituitary cells: its localization and possible function in gonadotrophs.

Arachidonate 12-lipoxygenase, which oxygenates positions 12 and 13 of arachidonic and linoleic acids, is present in porcine anterior pituitary cells. Colocalization of the 12-lipoxygenase with various pituitary hormones was examined by immunohistochemical double-staining using antibodies against 12-lipoxygenase and various anterior pituitary hormones. Under light microscopy, approximately 7% of the cells producing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were positive for 12-lipoxygenase, whereas the enzyme was detected in less than 2% of the cells producing thyrotrophin, prolactin, growth hormone (GH), and adrenocorticotrophin. In an attempt to examine the participation of 12-lipoxygenase metabolites in pituitary hormone release, we incubated the primary culture of porcine anterior pituitary cells with 12-hydroperoxy-arachidonic acid or 13-hydroperoxy-linoleic acid. Significant stimulation of LH and FSH release by these hydroperoxides was observed at 10 microM in a time-dependent manner. At doses around 10 microM these compounds produced responses of similar magnitude to 1 nM gonadotrophin-releasing hormone (GnRH), but higher concentrations (30 microM) of the compounds were required for GH release. In contrast, 12-hydroxy-arachidonic and 13-hydroxy-linoleic acids were almost ineffective. Furthermore, the gonadotrophin release by 1 nM GnRH was inhibited by nordihydroguaiaretic acid (a lipoxygenase inhibitor) with an IC50 of about 5 microM. Thus, the hydroperoxy (but not hydroxy) products of 12-lipoxygenase may be involved in the release of pituitary hormones especially LH and FSH.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1996

[A photoallergenicity study of prulifloxacin (NM441) in guinea pigs].

Photoallergenicity of prulifloxacin, a new antibacterial agent, was examined using guinea pigs compared with those of the other quinolone antibacterial drugs, ofloxacin (OFLX), lomefloxacin (LFLX), ciprofloxacin (CPFX), enoxacin (ENX) and nalidixic acid (NA). Prulifloxacin and other drugs were orally administered at minimal phototoxic doses 1 hr before UVA (18 J/cm2) irradiation. This photosensitization procedure was daily repeated for 5 days. On 16 days after the final sensitization, the animals were challenged with UVA (18 J/cm2) after the administration of correspondent substances at maximal non-phototoxic doses. Photoallergic reactions were induced by OFLX (40 mg/kg), LFLX (3 mg/kg), CPFX (170 mg/kg) and ENX (80 mg/kg), but were not observed in prulifloxacin (170 mg/kg) and NA (30 mg/kg). These results show that photoallergenicity of prulifloxacin were less severe than those of the other quinolone antibacterial drugs under the conditions of this study.

Animals↗
PubMed1995

Presence of estrogen receptors in aromatase-immunoreactive neurons in the mouse brain.

The present study was undertaken to demonstrate estrogen receptors in aromatase-immunoreactive neurons showed the immunoreactivity for estrogen receptors in the cell nuclei in the medial subdivision of the bed nucleus of the stria terminalis and the posterodorsal division of the medial amygdaloid nucleus, but a few did in the medial preoptic area. These results suggest that aromatase-immunoreactive neurons in the former two areas are regulated by steroids through estrogen receptors in their cell nuclei.

Animals↗
PubMed1995

Long-term maintenance of functional rat hepatocytes in primary culture by additions of pyruvate and various hormones.

Mature adult rat hepatocytes were cultured as monolayers in serum-free Williams medium E containing 10(-7) M each of insulin (Ins), dexamethasone (Dex) and triiodothyronine (T3) and 30 mM pyruvate. The hepatocytes remained morphologically intact for at least 14 days, during which period they maintained normal liver functions such as the expressions of cytochrome P-450 mRNA and glucokinase and secretion of albumin. They also retained the ability to resume proliferation. Cells cultured with pyruvate had a much higher ATP level than those without pyruvate, suggesting that pyruvate can sustain functional hepatocytes for a long period in culture in the presence of Ins, Dex and T3, probably by producing enough energy for their maintenance.

Adenosine Triphosphate↗
PubMed1995

Modulation of noradrenaline release through presynaptic alpha 2-adrenoceptors in congestive heart failure.

Stimulation of presynaptic alpha 2-adrenoceptors inhibits the release of noradrenaline from sympathetic nerve endings; however, the extent to which it operates in patients with congestive heart failure is still unknown. To investigate the degree of negative feedback to the release of noradrenaline via presynaptic alpha 2-adrenoceptors at sympathetic nerve endings, we measured plasma noradrenaline levels before and after the injection of phentolamine (i.e., plasma noradrenaline concentration at rest, plasma noradrenaline concentration after phentolamine injection [NAph], and the phentolamine-induced increase in plasma noradrenaline [delta NAph]). Plasma noradrenaline concentration at rest, NAph, and delta NAph increased in a stepwise manner from New York Heart Association class I to class III. A positive correlation was found between the plasma noradrenaline at rest and delta Naph (n = 123, r = 0.697, p < 0.001). These results suggest that the enhanced release of plasma noradrenaline is substantially buffered by the mechanism of noradrenaline release-inhibitory presynaptic alpha 2-adrenoceptors in patients with congestive heart failure, and this buffer serves to protect organs such as the heart from excess sympathetic stimulation.

Aged↗
PubMed1995

Coexistence of nitric oxide synthase, tyrosine hydroxylase and vasoactive intestinal polypeptide in human penile tissue--a triple histochemical and immunohistochemical study.

Recently, nitric oxide (NO) has been believed to act as a neuronal messenger to mediate penile erection. In the present study using human penile tissue, we investigated the coexistence of neuronal NO synthase (NOS), tyrosine hydroxylase (TH) and vasoactive intestinal polypeptide (VIP) by a triple staining method using NADPH diaphorase (ND) staining, a specific histochemical marker of neuronal NOS, and immunohistochemical staining for TH and VIP. Numerous ND-positive nerve fibers and TH-containing fibers were seen in axon bundles, but their distributions were different. Only a few axons in the bundles showed VIP immunoreactivity. Abundant fine varicose nerve terminals innervating cavernous smooth muscles and deep and helicine arteries were observed. The proportion of fibers showing TH-immunoreactivity in ND-positive terminals in the cavernous space was about 25%, and that of VIP was about 40%. Vasoactive intestinal polypeptide may act as a coworker in these fibers both in cavernous trabeculae and around arteries, as about 40% of NOS-containing fibers also showed VIP immunoreactivity. The physiological significance of the colocalization of TH and NOS is unclear, and further studies are required to know the physiological significance of the colocalization of NOS and other neurotransmitters in penile tissue.

Amino Acid Oxidoreductases↗
PubMed1995

Immunocytochemical localization of platelet-type arachidonate 12-lipoxygenase in mouse blood cells.

Arachidonate 12-lipoxygenase is an enzyme that oxygenates the 12 position of arachidonic acid to produce its 12-hydroperoxy derivative. We were interested in the tissue distribution and subcellular localization of the platelet-type 12-lipoxygenase, which is distinguished from the leukocyte type by several criteria. Antiserum was raised in rabbits against purified recombinant arachidonate 12-lipoxygenase of human platelets. When mouse bone marrow cells and lung were immunostained and observed by light and electron microscopy, the positively stained cells were platelets, megakaryocytes, and eosinophils. 12-Lipoxygenase was localized in the cytoplasm of platelets but was hardly detectable in the plasma membrane and intracellular organelles. The enzyme was found in the cytoplasm of immature megakaryocytes with kidney-shaped nuclei and a few profiles of demarcation membranes, as well as in the mature form with well-developed demarcation membranes. These results indicated the expression of 12-lipoxygenase at an early stage in the course of megakaryocytopoiesis.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Plasma adrenaline modulates alpha 1-adrenoceptor mediated pressor responses and the baroreflex control in patients with borderline hypertension.

Plasma level of adrenaline has been reported to be elevated in borderline hypertension. However, its role in developing and maintaining hypertension is still not completely understood. This study aimed to estimate the role of plasma adrenaline in developing hypertension. Ten patients with borderline hypertension (BHT) and 10 age-matched normotensive subjects were included. We infused at least three graded doses of phenylephrine, an alpha-adrenoceptor agonist, into the antecubital vein of subjects lying quietly in a supine position. Mean blood pressure was measured continuously through the right radial artery. Cardiac output was measured by the thermodilution method before and after the administration of each dose of phenylephrine infusion. We obtained dose-response curves for mean blood pressure and total peripheral resistance to phenylephrine. Baroreflex sensitivity was calculated by plotting the longest R-R intervals against the elevated peak mean blood pressure after the infusion of each dose of phenylephrine. Plasma noradrenaline and adrenaline concentrations at rest were measured by high performance liquid chromatography coupled with trihydroxyindole fluorimetric detection. The plasma adrenaline level at rest was higher in patients with BHT than in normotensive subjects. With graded infusion of phenylephrine, both the pressor responses and the changes in total peripheral resistance were greater in patients with BHT than in normotensive subjects. The plasma adrenaline level was positively correlated with the slope of dose response curves for the increments of mean blood pressure to phenylephrine (r = 0.60, p < 0.01). Baroreflex sensitivity was reduced in patients with BHT as compared with normotensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1995

Further observations on the fine structure of the development of the interrenal tissue of the chick embryo.

The interrenal tissue of 8-21 day-old White Leghorn chick embryos and of 1 day-old chicks was studied by means of electron microscope. The interrenal cells in 8-10 day-old embryo are characterized by the presence of numerous free ribosomes, very small amount of endoplasmic reticulum, oval or club-shaped mitochondria with lamellar cristae and of a few small lipid droplets. The fine structural signs for steroid secretion, such as round or oval mitochondria with tubular cristae and smooth endoplasmic reticulum begin to appear in 11-13 day-old embryo, and the interrenal cell of the 16 day-old embryo shows typical morphological characteristics for the steroid-secreting cell. After 16 days, the cytoorganelles of the interrenal cell do not show any qualitative changes. These facts may indicate that the interrenal cell of the domestic fowl is functionally differentiated around 11 days of incubation at latest. The interrenal tissue of 8-9 day-old embryos somewhat resembles a tubular gland, though the zonula occludens is not present. In addition, the interrenal cell shows an incomplete cell polarity, throughout the embryonic days examined. These findings indicate that the interrenal cell of the embryonic domestic fowl, which is derived from a mesothelium, remains slightly an epithelial nature.

Animals↗
PubMed1995

Characterization of arachidonate 12-lipoxygenase found in the liver of mongrel dog and its immunohistochemical localization in neutrophils.

The cytosol fraction of non-parenchymal cells isolated from the liver of adult mongrel dogs converted arachidonic acid to 12S-hydroxy-5,8,10,14-eicosatetraenoic acid. The arachidonate 12-lipoxygenase enzyme reacted with linoleic and alpha- and gamma-linolenic acids as well as arachidonic acid. The enzyme was immunoprecipitable with an antibody against the leukocyte 12-lipoxygenase, but not with an antibody against the platelet 12-lipoxygenase. By immunohistochemical observation with anti-leukocyte 12-lipoxygenase antiserum, hepatocytes, Kupffer cells and sinusoidal endothelial cells were not immunostained, but a large number of neutrophils located in sinusoidal cavities were positively stained. The 12-lipoxygenase activity thus detected may be attributed predominantly to the neutrophils appearing in sinusoidal cavities rather than the non-parenchymal cells in the liver of mongrel dog upon infection. In agreement with this finding there was essentially no neutrophil accumulation in the liver of Beagle dog which had no bacterial and parasitic infection.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1994

Fas-mediated apoptosis in primary cultured mouse hepatocytes.

The Fas antigen is a member of the tumor necrosis factor/nerve growth factor receptor family and is expressed in tissues such as the thymus, liver, and ovary. Agonistic anti-Fas antibodies have cytolytic activity against cell lines expressing the Fas antigen. In this study, we show that anti-Fas antibody can induce the death of mouse hepatocytes in primary culture. Cell death via apoptosis was evidenced by the fact that the dying cells displayed DNA fragmentation, extensive surface bleb formation, and chromatin condensation. Anti-Fas antibody alone induced apoptosis in less than 20% of the cultured hepatocytes, whereas all cells were killed within 24 h by anti-Fas antibody in the presence of actinomycin D, cycloheximide, or protein kinase C (PKC) inhibitors such as H-7 and HA1004. These results indicate that the Fas antigen expressed in mouse hepatocytes functionally transduces the apoptotic signal and suggest that cultured mouse hepatocytes express protective proteins against apoptosis and that phosphorylation by PKC is also involved in protection of the hepatocytes from Fas-mediated apoptosis.

Animals↗
PubMed1994

Immunocytochemical localization of aromatase-containing neurons in the rat brain during pre- and postnatal development.

The present immunohistochemical study demonstrates the ontogenetic appearance of aromatase-immunoreactive neurons in several discrete regions of the hypothalamus and limbic system in the rat brain, using a purified antibody against human placental aromatase cytochrome P450. Immunoreactive cells were first detected in the preoptic area on the 13th day of embryonic life (E13), and additionally in the bed nucleus of the stria terminalis on E15. Labeled cells were also found in the medial amygdaloid nucleus and the ventromedial nucleus on E16, and some were detected in the arcuate nucleus on E19. As gestation progressed, the number and the immunoreactivity of these cells gradually increased and peaked within definite periods of perinatal life and thereafter declined or disappeared. The immunoreactive cells were also found in the central amygdaloid nucleus and the lateral septal nucleus, and in the ventral pallidum, after the 14th day of postnatal life (P14) and 30th day (P30), respectively. The distribution of aromatase-immunoreactive neurons was similar between the sexes, while the immunoreactivity was higher in males than in females after late gestational days. No immunoreaction was detectable in other regions of the telencephalon or midbrain at any time periods studied. The aromatase-immunoreactive neurons in the specific regions may be involved in the sexual differentiation of the brain.

Age Factors↗