Search PubMed⌕ Search

Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 55 records · Page 3Linked to original sources
PubMed2001

Immunohistochemical study of the distribution of endocrine cells in the gastrointestinal tract of the camel (Camelus bactrianus).

The regional distribution and relative frequency of endocrine cells in the gastrointestinal tract of the camel, Camelus bactrianus, were investigated using immunohistochemical methods. Ten types of immunoreactive (IR) endocrine cells were identified in this study. Among these cell types, only serotonin- and somatostatin-IR cells were detected in almost all regions of the gastrointestinal tract. Most of the cell types showed peak density in the pyloric gland region. The others showed restricted distribution: gastrin, cholecystokinin (CCK), motilin, bovine pancreatic polypeptide (BPP), and (gastric) substance P in the stomach; gastrin, CCK, BPP, gastric inhibitory polypeptide (GIP), glucagon, peptide tyrosine tyrosine (PYY) and substance P in the small intestine; and CCK, motilin, BPP, and PYY in the large intestine. Fundamentally the distribution pattern of endocrine cells in the gastrointestinal tract of the camel is similar to that of cattle. The distribution and frequency of endocrine cells in the glandular sac region are the same as those of the cardiac gland.

Animals↗
PubMed2001

Plasma endothelin-1 and atrial natriuretic peptide levels during prolonged (24-h) non-acidemic hypoxemia in fetal goats.

OBJECTIVE: The purpose of this study was to investigate the effects of prolonged (24-h) non-acidemic hypoxemia on plasma endothelin-1 and atrial natriuretic peptide (ANP) in fetal goats. METHODS: During continuous infusion of nitrogen into the maternal trachea, fetal plasma endothelin-1 and ANP levels were measured in nine chronically instrumented goat fetuses at 117-129 days' gestation. Endothelin-1 and ANP were measured by radioimmunoassay. RESULTS: Fetal arterial pO(2) decreased significantly from 23.1 +/- 1.0 mmHg (control) to 15.2 +/- 0.9 mmHg during the first 2 h of hypoxemia and to 15.7 +/- 1.1 mmHg at the end of the experimental period of hypoxemia. The plasma endothelin-1 concentration increased from 10.6 +/- 1.9 pg/ml to 20.4 +/- 4.3 pg/ml (p < 0.05) during the first 2 h and was 19.7 +/- 2.4 pg/ml (p < 0.01) at the end of the experimental period. The plasma ANP concentration also increased, from 20.3 +/- 5.5 pg/ml to 23.0 +/- 4.7 pg/ml in the first 2 h and then to 58.0 +/- 8.8 pg/ml (p < 0.05) at the end of the experimental period. There was a significant negative correlation between fetal plasma endothelin-1 and pO(2), but no significant correlation was found between fetal plasma ANP and pO(2). CONCLUSIONS: Prolonged non-acidemic hypoxemia induces a continuous increase in fetal plasma endothelin-1 and ANP levels. Fetal plasma ANP increases time-dependently but endothelin-1 remains constant during hypoxemia.

Animals↗
PubMed2001

Parent and caregiver compliance with poison center advice.

BACKGROUND: The purpose of this study was to assess the compliance of parents and caregivers whose children (under 6 years of age) accidentally ingested antihistamines, decongestants, or both. METHODS: We used a prospective-descriptive study design and developed a convenience sample from eligible calls retrieved from the records from January 19, 1999 to February 28, 1999. Poison control specialists categorized the children into two groups: toxic and needing treatment in a hospital or nontoxic and not needing treatment at a hospital. Compliance with Poison Control Center advice was measured by follow-up telephone calls made by a research assistant within 7 days of the initial call. RESULTS: One hundred forty-seven calls were retrieved and followed. One hundred and seven (72.8%) callers had been advised that no treatment was needed. One hundred (93.4%) of these 107 followed Poison Control Centre advice. Forty (27.2%) of the 147 callers were advised to take their child to an emergency department. Thirty-nine (97.5%) of these 40 complied with the advice. There was no statistically significant difference in compliance rates between the two groups (chi2 = 0.306, df = 1, p = 0.58). DISCUSSION AND CONCLUSIONS: In this group of callers, compliance was high. Reasons for noncompliance included caregiver anxiety, specifically the need for a second opinion. Future studies are needed to determine the level of compliance more definitively. Studies should include subjects from other age groups, other exposures, and other types of callers.

Child, Preschool↗
PubMed2001

Differential subcellular actions of ACE inhibitors and AT(1) receptor antagonists on cardiac remodeling induced by chronic inhibition of NO synthesis in rats.

Chronic inhibition of NO synthesis induces cardiac hypertrophy independent of systemic blood pressure (SBP) by increasing protein synthesis in vivo. We examined whether ACE inhibitors (ACEIs) enalapril and temocapril and angiotensin II type-I receptor antagonists (angiotensin receptor blockers [ARBs]) losartan and CS-866 can block cardiac hypertrophy and whether changes in activation of 70-kDa S6 kinase (p70S6K) or extracellular signal-regulated protein kinase (ERK) are involved. The following 13 groups were studied: untreated Wistar-Kyoto rats and rats treated with NO synthase inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME), D-NAME (the inactive isomer of L-NAME), L-NAME plus hydralazine, L-NAME plus enalapril (3 mg. kg(-1). d(-1)) or temocapril (1 or 10 mg. kg(-1). d(-1)), L-NAME plus losartan (10 mg. kg(-1). d(-1)) or CS-866 (1 or 10 mg. kg(-1). d(-1)), L-NAME plus temocapril-CS866 in combination (1 or 10 mg. kg(-1). d(-1)), and L-NAME plus rapamycin (0.5 mg. kg(-1). d(-1)). After 8 weeks of each experiment, ratios of coronary wall to lumen (wall/lumen) and left ventricular weight to body weight (LVW/BW) were quantified. L-NAME increased SBP, wall/lumen, and LVW/BW compared with that of control. ACEIs, ARBs, and hydralazine equally canceled the increase in SBP induced by L-NAME. However, ACEIs and ARBs equally (but not hydralazine) attenuated increase in wall/lumen and LVW/BW induced by L-NAME. The L-NAME group showed both p70S6K and ERK activation in myocardium (2.2-fold and 1.8-fold versus control, respectively). ACEIs inactivated p70S6K and ARBs inactivated ERK in myocardium, but hydralazine did not change activation of either kinase. Thus, ACEIs and ARBs modulate different intracellular signaling pathways, inhibiting p70S6K or ERK, respectively, to elicit equal reduction of cardiac hypertrophy induced by chronic inhibition of NO synthesis in vivo.

Angiotensin Receptor Antagonists↗
PubMed2001

The 5-HT1A receptor agonist 8-hydroxy-2-di-n-(propylamino)tetralin (8-OH-DPAT) induces hyperglucagonemia in rats.

Effects of the 5-HT1A receptor agonist 8-hydroxy-2-di-n-(propylamino)tetralin (8-OH-DPAT) on plasma glucagon levels were investigated. 8-OH-DPAT increased plasma glucose and glucagon levels in rats. Both hyperglycemia and hyperglucagonemia elicited by 8-OH-DPAT were prevented by the 5-HT1A receptor antagonist pindolol and prior adrenodemedullation. These results suggest that increases in plasma glucagon levels induced by 8-OH-DPAT were based on the adrenaline release from the adrenal gland and its effects may contribute to its hyperglycemic effects.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Effects of the 5-HT2 receptor antagonist, ritanserin on hyperthermia and depletion of 5-HT in frontal cortex induced by a 5-HT releasing drug, p-chloroamphetamine (PCA) in mice.

Effects of the 5-HT2 receptor antagonist, ritanserin on hyperthermia and depletion of 5-HT induced by the 5-HT-releasing drug, p-chloroamphetamine (PCA) were investigated. Ritanserin significantly suppressed PCA-induced hyperthermia in mice. PCA elicited decreases in 5-HT levels in the mouse frontal cortex. 5-HT reduction elicited by PCA was also attenuated by pretreatment with ritanserin. Since hyperthermia facilitates neurotoxicity induced by amphetamine analogue, ritanserin may inhibit PCA-induced 5-HT neurotoxicity by inhibiting hyperthermia.

Animals↗
PubMed2001

The 5-HT2C/2B receptor agonist m-chlorophenylpiperazine (mCPP) inhibits 2-deoxy-D-glucose (2-DG)-induced hyperphagia in rats.

Effects of the 5-HT2C2/2B receptor agonist m-chlorophenylpiperazine (mCPP) on hyperphagia elicited by 2-deoxy-D-glucose (2-DG) were investigated in rats. mCPP apparently reduced 2-DG-induced hyperphagia. Suppressive effects of mCPP on hyperphagia induced by 2-DG were inhibited by the 5-HT2A/2B/2C receptor antagonist, ritanserin, although the 5-HT2, receptor antagonist ketanserin was without effect. Thus, inhibitory effects of mCPP on 2-DG-induced hyperphagia are mediated by the 5-HT2C/2B receptor. Our results demonstrate that mCPP can inhibit the bulimia model, 2-DG-induced hyperphagia.

Animals↗
PubMed2001

Immunolocalization of gastrin-releasing peptide in the bovine uterus and placenta.

Gastrin-releasing peptide (GRP), a mammalian homologue of amphibian bombesin, has been suggested to be a novel regulatory peptide in the reproductive tract during pregnancy. In this study, the localization of GRP in the bovine uterus and placenta was demonstrated by immunohistochemistry. Uterine and placental samples were collected from nonpregnant and pregnant specimens, respectively. Tissue sampling was done from the caruncle and intercaruncle of the uterus, and from the placentome (caruncle and cotyledon) and intercotyledon of the placenta. In all the tissues examined, GRP was detected although its immunoreactivity was observed at various degrees. In the uterus, moderate immunoreactivity for GRP was observed in the uterine gland epithelial cells. In the placenta, strong immunoreactivity for GRP was demonstrated in the uterine gland epithelial cells; moderate in superficial epithelial cells; and weak in the trophoblasts, trophoblastic giant cells and cryptal epithelial hybrid cells. In both nonpregnant and pregnant animals, GRP was immunolocalized in the uterine gland secretions and was found predominantly in the supranuclear region of the uterine gland epithelial cells. These findings may suggest that GRP is secreted into the uterine lumen and regulates the intrauterine environment of both the nonpregnant and pregnant bovine by exocrine, autocrine and/or paracrine manner.

Animals↗
PubMed2001

Prepubertal changes in immunoreactive inhibin concentration in blood serum and testicular tissue in Holstein bull calves.

Age-related changes in immunoreactive inhibin (ir-inhibin) levels and the relationship among ir-inhibin, gonadotropins and testosterone were examined in 53 Holstein bull calves from neonates to 8.6 months old. Serum levels of ir-inhibin, luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, as well as ir-inhibin levels in testicular extracts, and testicular sizes were measured. All hormones were measured by specific radioimmunoassays. The concentrations of ir-inhibin in serum and testicular tissue were high in neonatal calves and tended to decrease with age. In contrast, serum concentrations of gonadotropins did not show any age-related changes within the experimental period. Serum testosterone levels and testicular sizes (length, width and weight) were positively correlated with age. Furthermore, a positive immunostaining to antiserum for the inhibin alpha-subunit was immunocytochemically observed only in Sertoli cells of the seminiferous tubules from neonates to calves less than 6 months old. These results indicate that the immature bovine testis produces and secretes high levels of ir-inhibin and that the Sertoli cells are a major source of ir-inhibin in prepubertal bull calves.

Age Factors↗
PubMed2001

Cycle of the seminiferous epithelium in the Java fruit bat (Pteropus vampyrus) and the Japanese lesser horseshoe bat (Rhinolophus cornutus).

The cycle of the seminiferous epithelium in the Java fruit bat, Pteropus vampyrus, and the Japanese lesser horseshoe bat, Rhinolophus cornutus, was investigated by light microscopy and the characteristics of spermiogenesis were compared between these two species. In the Java fruit bat, the cycle of the seminiferous epithelium was divided into 11 stages and developing spermatids were subdivided into 13 steps. While in the Japanese lesser horseshoe bat, the cycle of the seminiferous epithelium was divided into 10 stages and developing spermatids were subdivided into 13 steps. Excepting slight morphological differences, the characteristics of acrosomal formation in both species were almost similar with each other. In the Java fruit bat after stage VII, the acrosome gradually elongated, flattened and finally became scoop-like in shape. In the Japanese lesser horseshoe bat after stage VIII, the acrosome elongated, flattened and then slightly shortened. Before spermiation, the acrosome became long spatula-like in shape. The elongation and flattening of spermatids in these two species were similar to those in insectivores. The finding may reflect the fact that the order Chiroptera is phylogenetically close to the order Insectivora.

Acrosome↗
PubMed2001

Galanin-like immunoreactive neural elements in domestic ruminant pancreas.

The distribution and ontogeny of the galanin-like immunoreactive (Gal-IR) neural structures in the pancreas of cattle, sheep and goat were investigated immunohistochemically. The present study confirmed the previous findings on the immunolocalization of galanin both in the neural elements and endocrine cells of cattle, and reported for the first time its exclusive localization in the neural elements of sheep and goat. The frequency of Gal-IR nerve fibers and nerve cell bodies was high in cattle and low in sheep and goat. Their first detection was at the first fetal trimester in cattle and third trimester in sheep and goat. In cattle, a marked increase in the frequency of Gal-IR nerve fibers was observed from the third trimester to early neonatal stage followed by a decrease after three months postnatal. In contrast to the non-preferential distribution pattem in sheep, the Gal-IR nerve fibers in cattle and goat pancreas were predominantly associated with the acini, excretory ducts and blood vessels, but rarely detected in the pancreatic islets. The Gal-IR nerve cell bodies were observed as isolated bodies in the intra- and interlobular connective tissues and as a group within the intrapancreatic ganglia. At the vicinity of the nerve cell bodies, Gal-IR nerve fibers were observed. The present findings may suggest that: (1) galanin regulates pancreatic function as neurotransmitter/neuromodulator in ruminants; (2) galanin plays a more important role in large than in small ruminants; and (3) particularly in cattle, it exerts its most dramatic effect during perinatal development.

Animals↗
PubMed2001

Adrenal glands in small smooth-tailed tree shrew (Dendrogale murina).

Adrenal glands of small smooth-tailed tree shrews (Dendrogale murina), four males and two females, caught and fixed in Thailand were observed macroscopically and histologically. They were located at the cranio-medial sides of the kidney. They were elongated in shape and consisted of a cortex and medulla. The cortex could be subdivided into three zones by the cell arrangement and the morphology of nuclei, cytoplasm and cell strands, like in other mammalian species. The tree shrew seemed to share more morphological characteristics with some laboratory rodents than some of non-human primates.

Adrenal Glands↗
PubMed2001

Cytotoxic T cells play no essential role in acute rejection of orthotopic corneal allografts in mice.

PURPOSE: To determine whether cytotoxic T cells of the direct alloreactive type are activated and responsible for early, acute failure of orthotopic corneal allografts observed in eyes of C57BL/6 but not of BALB/c mice. METHODS: Corneas from BALB/c and BALB.B mice were placed orthotopically in eyes of C57BL/6 and beta-2 microglobulin knockout mice (deficient in CD8(+) cytotoxic T cells). Graft fates were assessed clinically, and the T lymphocytes of recipients were assayed for the capacity to lyse target cells bearing donor major (MHC) and/or minor histocompatibility (minor H) antigens (direct and indirect pathways, respectively). RESULTS. Similar to BALB/c recipients, C57BL/6 mice with rejected cornea allografts acquired donor minor H-specific T cells. Unlike BALB/c recipients, C57BL/6 mice-both rejectors and acceptors-acquired donor MHC-specific T cells. beta-2 Microglobulin knockout mice showed rejection of corneal allografts in a manner indistinguishable from C57BL/6 mice, including early, acute rejection, yet T cells from beta-2 microglobulin knockout recipients of corneal allografts displayed no cytotoxic T cells specific for either donor MHC or minor H alloantigens. CONCLUSIONS: Although C57BL/6 mice acquired donor MHC-specific cytotoxic T cells (direct alloreactive cells), neither these cells nor donor minor H-specific cytotoxic T cells (indirect alloreactive cells) play any essential role in corneal allograft rejection, including the early acute failure uniquely observed in C57BL/6 eyes.

Acute Disease↗
PubMed2001

[Nontuberculous atypical mycobacterial infection with progressive pancytopenia in a patient with myelodysplastic syndrome].

We describe a patient with myelodysplastic syndrome (MDS) who developed disseminated infection due to nontuberculous mycobacteria (NTM). A 64-year-old man was admitted because of persistent fever that had been unresponsive to antibiotics. Bone marrow aspiration specimens showed myelodysplasia (RA), but the origin of the fever was unclear. Cytopenia worsened to a level that required transfusion of red blood cells and platelets. Repeated bone marrow examination revealed hypoplasia with hemophagocytosis. Several weeks later, photochromogenic NTM was isolated from bone marrow specimens, sputum and broncho-alveolar lavage (BAL) fluid which had been obtained on admission. Antituberculosis treatment with clarithromycin markedly improved the patient's general condition and hematological abnormalities. Three months after resolution of the NTM infection, the peripheral blood monocyte count increased, the fever recurred, and the patient suddenly died of myocardial infarction. Disseminated infection with NTM has gained attention as a frequent complication of AIDS, and NTM can also be one of the pathogens causing disseminated infection in patients with MDS. In the present case, infection with mycobacteria that normally would have been digested by macrophages and would not have caused disseminated infection in a healthy individual, was probably related to the clinical features including high fever, severe pancytopenia and hemophagocytosis.

Disease Progression↗
PubMed2001

[Vesicoureteral reflux in a family].

We treated 3 cases of primary familial vesicoureteral reflux (VUR). Case 1: A 6-year-old boy had a grade III VUR in the left. Case 2: A 9-year-old boy, who was the elder brother of case 1, had grade III VUR in the right and grade V VUR in the left. Case 3: An 11-year-old girl, who was the elder sister of case 1 and case 2, had bilateral grade V VUR. VUR disappeared after anti-reflux operations in all cases.

Child↗
PubMed2000

Increased phospholipase D2 activity during hypoxia-induced death of PC12 cells: its possible anti-apoptotic role.

During hypoxic incubation (1% O2) of PC12 cells, the PLD activity was transiently increased within 12h, followed by a gradual decrease. In the in vitro assay, the increased PLD activity was independent of GTPgammaS required for PLD1 or of oleic acid for PLD(OA), suggesting the activation of PLD2. The level of PLD2 protein showed no change up to 12h but a gradual decrease after 24 h. Pretreatment of cells with S. chromofuscus PLD resulted in inhibition of hypoxia-induced apoptotic cell death. In contrast, 1-butanol, but not 2-butanol, potentiated cell death. Moreover, the number of apoptotic cells significantly reduced in PC12 cells over-expressing PLD2. These results raise the possibility that PLD2 activation may play an anti-apoptotic role in hypoxia-induced cell death.

1-Butanol↗
PubMed2000

Serum leptin levels after central and systemic injection of a serotonin precursor, 5-hydroxytryptophan, in mice.

Effects of peripheral and central injections of a serotonin (5-hydroxytryptamine, 5-HT) precursor, 5-hydroxytryptophan (5-HTP), on serum leptin levels were studied in mice. Intracerebroventricular (i.c.v.) injection of 5-HTP or 5-HT did not increase serum leptin levels, although the peripheral injection of 5-HTP elicited an apparent hyperleptinemia. The elevation of serum leptin levels in mice induced by the peripheral injection of 5-HTP was inhibited by pretreatment with the peripheral aromatic amino acid decarboxylase inhibitor, benserazide. Furthermore, the peripheral injection of 5-HT increased serum leptin levels. These results suggest that the hyperleptinemia following systemic injection of 5-HTP is elicited by 5-HT formed in the peripheral system.

5-Hydroxytryptophan↗