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Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 199 records · Page 11Linked to original sources
PubMed1995

The involvement of the peripheral 5-HT2A receptor in peripherally administered serotonin-induced hyperglycemia in rats.

The mechanism of the hyperglycemic response to intraperitoneally administered serotonin (5-HT) was studied in rats. 5-HT i.p.-induced hyperglycemia was strongly antagonized by the 5-HT2A receptor antagonist ketanserin. 5-HT did not affect the serum insulin levels and increased plasma glucagon levels only at the high dose of 10 mg/kg. 5-HT dose-dependently induced a remarkable increase in plasma adrenaline levels and these effects were antagonized by ketanserin. 5-HT-induced hyperglycemia was abolished by adrenodemedullation. These results suggest that the hyperglycemic effects of 5-HT are closely related to the release of adrenaline from the adrenal gland, mediated by 5-HT2A receptors.

Animals↗
PubMed1995

A case of uterine cervical adenoid cystic carcinoma: immunohistochemical study for basement membrane material.

BACKGROUND: Adenoid cystic carcinoma is a rare neoplasm of the cervix. Only two reports of immunohistochemical studies for basement membrane material in adenoid cystic carcinoma of the cervix have been reported. CASE: An 80-year-old Japanese woman complained of atypical vaginal bleeding and underwent removal of a cervical polyp; the biopsy specimen revealed a solid variant of adenoid cystic carcinoma. The tumor was composed of nests and nodules of small carcinoma cells, and there were few characteristic cribriform patterns. Immunohistochemical findings for type IV collagen and laminin revealed intercellular cylinders composed of basement membrane material in the solid area without a cribriform pattern. CONCLUSION: The immunohistochemical finding of intercellular cylinders that reacted for type IV collagen was useful for the diagnosis of a solid variant of adenoid cystic carcinoma.

Aged↗
PubMed1995

Immunocytochemical colocalizations of serotonin, aromatic L-amino acid decarboxylase and polypeptide hormones in A- and PP-cells of the chicken endocrine pancreas.

The colocalization of serotonin and aromatic L-amino acid decarboxylase (AADC) in the avian pancreatic polypeptide-containing PP-cells and glucagon-storing A-cells of the chicken endocrine pancreas was investigated using combined pre-embedding immuno-peroxidase and post-embedding immunogold electron microscopic immunocytochemistry. The avian pancreatic polypeptide-immunoreactive cells manifested by the labeling of immunogold particles on secretory granules were also immunoreactive with antisera directed against serotonin and AADC, an enzyme involved in the synthesis of serotonin. In PP-cells immunoreactivity against the anti-serotonin serum was stronger in secretory granules than in the cytoplasmic matrix, whereas immunoreaction with the anti-AADC serum was observed to be more intense in the cytoplasmic matrix. Immunoreactions with the serotonin and AADC antisera were also found in secretory granules of glucagon-storing A-cells. These results indicate that serotonin is co-stored within secretory granules of both A- and PP-cells, and that AADC is localized within secretory granules of A-cells, and may be present in the cytoplasmic matrix of PP-cells. It is probable that serotonin is synthesized and released simultaneously with secretory granules from both A- and PP-cells of the chicken endocrine pancreas.

Animals↗
PubMed1995

The effects of the serotonin1A receptor agonist buspirone on tolbutamide-induced hypoglycemia in rats.

The effects of the serotonin1A(5-HT1A) receptor agonist buspirone on hypoglycemia elicited by tolbutamide were investigated in rats. Buspirone, at doses not affecting plasma glucose levels, inhibited the hypoglycemic effects of tolbutamide. The inhibitory effects of buspirone on tolbutamide-induced hypoglycemia were antagonized by the 5-HT1A receptor antagonist pindolol. As tolbutamide is known to induce hypoglycemia by facilitating insulin release, the effects of buspirone on a tolbutamide-induced increase in serum insulin levels were also studied. However, buspirone did not affect tolbutamide-induced insulin release. Adrenodemedullation inhibited the effects of buspirone. These results suggest that buspirone inhibits tolbutamide-induced hypoglycemia mediated by the 5-HT1A receptor, and adrenaline release may be involved in the effects of buspirone.

Animals↗
PubMed1995

Serotonin2 (5-HT2) receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) inhibits chlorpromazine- and haloperidol-induced hypothermia in mice.

Chlorpromazine- and haloperidol-induced hypothermia were examined in mice. The alpha 1 receptor agonist phenylephrine partially antagonized the hypothermia, while the dopamine D2 receptor agonist apomorphine did not inhibit it. The central serotonin2 (5-HT2) receptor agonist I-2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) strongly inhibited the chlorpromazine- and haloperidol-induced hypothermia. Both drugs at doses which can elicit hypothermia antagonized head twitch responses mediated by the central 5-HT2 receptor. These results suggest that the chlorpromazine- and haloperidol-induced hypothermia may be mediated by the blockade of the central 5-HT2 receptor.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1995

Ultrastructure of cardiac myocytes in the greater bandicoot rat (Bandicota indica).

Cardiac myocytes in the left ventricle and atrium of the greater bandicoot rat (Bandicota indica) were examined by transmission electron microscopy. The fine structure showed typical features of mammalian cardiac myocytes. In atrial myocytes, however, the areas occupied by mitochondria were much smaller than that filled with myofibrils. The decrease in mitochondria and the abundance of myofibrils are thought to be an ultrastructural adaptation to the large body size of this species. Many conducting myocytes were observed in both atrium and ventricle. The atrial conducting myocytes were ultrastructurally different from the Purkinje fibers of the ventricle. We suggest that the abundance and the ultrastructural variation of conducting myocytes are related to the physiological aspects, such as body size, of this animal.

Animals↗
PubMed1995

The geographic distribution of tuberculosis and pyridoxine supply in Ontario.

Acute poisoning with isoniazid causes generalized convulsions which should be treated with intravenous pyridoxine and a rapidly-acting anticonvulsant. The purpose of this study was to determine the correlation between the distribution of tuberculosis (as a proxy for isoniazid use) and acute care hospital supplies of intravenous pyridoxine (the antidote for isoniazid overdose). The distribution of tuberculosis was based on Ontario public health regions. The study was descriptive using simple linear regression to assess the degree of correlation. Only 15.6% of Ontario acute care hospitals have enough intravenous pyridoxine to treat an average isoniazid overdose. The distribution of tuberculosis and the number of hospitals in the region correlated best with hospital supplies of pyridoxine, although these variables explained only 22% and 23.7%, respectively, of the variation in supply. It does not appear that the distribution of tuberculosis is a major determinant of the availability of the isoniazid antidote, pyridoxine. Acute care hospitals in Ontario should re-evaluate their need for pyridoxine in light of the incidence of tuberculosis in their regions. Each hospital should stock at least 5 Gm of intravenous pyridoxine; additional amounts may be appropriate if there is an increased incidence in the area.

Antitubercular Agents↗
PubMed1995

Light microscopic studies of the stomach of the lesser mouse deer (Tragulus javanicus).

The stomach of the lesser mouse deer was studied at the light microscopic level using histological and immunohistochemical methods. The stomach was clearly differentiated into rumen, reticulum including reticular groove, a small transition zone and abomasum. The mucosal surface of the rumen, reticulum and transition zone was lined with a stratified squamous epithelium and that of the abomasum with a simple columnar type. The epithelial keratinization was weak in the rumen, floor of the reticular groove and transition zone, while it was strong in the reticulum, especially on the tip of the reticulum papillae. Large sinusoidal capillaries were often present in the ruminal papillae. In the ruminal mucosa, a thin layer of alpha-smooth muscle actin immunoreactive cells was demonstrated by immunohistochemistry. The muscularis mucosae of the reticulum was continuous and well-developed. The transition zone appeared as a nonglandular area having many low mucosal folds and two layers of tunica muscularis. The abomasal mucosa consisted of cardiac, proper gastric and pyloric glands. Cells immunoreactive for bovine pepsinogen and bovine prochymosin antisera were demonstrated in the abomasum. It is suggested that the characteristic features observed might be adaptations to a relatively rapid passage and rapid absorption of the fermentation products. There is some evidence that the transition zone is not a part of either the floor of the reticular groove or the abomasum, suggesting a possible reevaluation of the term used for the reticulo-abomasal orifice in the mouse deer.

Animals↗
PubMed1995

Cardiac musculature of the cranial vena cava in the common tree shrew (Tupaia glis).

Cardiac musculature of the cranial vena cava in the common tree shrew (Tupaia glis) was examined by light and transmission electron microscopy. The common tree shrew has well developed cardiac myocyte layers in the tunica media of the cranial vena cava, extending from the right atrium to the root of the subclavian vein. Because the common tree shrew belongs to a primitive group of mammals, the occurrence of cardiac musculature in the cranial vena cava may be a common feature in lower mammals. The development of this musculature indicates that active contraction of the cranial vena cava wall occurs in this species. Electron micrographs showed the typical ultrastructure of myocytes and nerve endings. These observations suggest that this musculature may serve as a regulatory pump for the return of venous blood to the right atrium and as a blood reservoir system under conditions of rapid heart rate. Additionally, the presence of atrial natriuretic polypeptide (ANP) was also demonstrated in the myocytes of the vena cava immunohistochemically. These findings show that the cardiac endocrine organ for ANP develops even in the principal veins including the cranial vena cava.

Animals↗
PubMed1995

An immunohistochemical study on the development of progastricsin-immunoreactive cells in the bovine abomasal mucosa.

The development of progastricsin-immunoreactive cells in the abomasal mucosa of cattle fetuses was studied by immunohistochemistry. Progastricsin-immunoreactive cells were detected first in the fundic and pyloric regions of 52 cm in crown-rump length (CRL) fetuses (about 180 days of gestation). The frequency of occurrence of progastricsin-immunoreactive cells and the intensity of their immunoreactivity increased with the progress of gestation, but most of these immunoreactivities were restricted to the basal portion of the fundic and pyloric glands. After birth, in the fundic mucosa, progastricsin immunoreactivities were found not only in the chief cells but also in the surface mucous cells of the gastric pits. In the cow, the immunoreactivity of the surface mucous cells was even stronger than that of the chief cells. In the pyloric mucosa, progastricsin immunoreactivities were found in the gastric pits and in the basal portion of the pyloric glands, but they were organized in small groups and showed a patchy distribution in the basal portions.

Abomasum↗
PubMed1995

[Treatment of facial arteriovenous malformation].

Arteriovenous malformations (AVMs) of the face are notoriously difficult lesions to manage because of the abundant vascular network in this region. We report three cases in which AVMs of the face were treated with endovascular embolization. Two cases with small AVM of the face and auricle were treated with direct puncture of the nidus and embolization with a small amount of n-butyl-cyanoacrylate (NBCA). In the third patient with a large AVM of the cheek, the external carotid artery (ECA) of which had been previously ligated surgically, percutaneous direct puncture of the ECA was performed. Superselective catheterization of each of the feeding arteries and embolization with a small amount of NBCA was then achieved. All cases demonstrated clinical and angiographical improvement. In two cases with a small AVM of the face and auricle, complete obstruction of the nidus was achieved. Direct puncture of the nidus and embolization with a small amount of NBCA was a safe and effective technique for the treatment of facial AVM.

Adult↗
PubMed1995

[Usefulness of the 24-hour delayed film of upper gastrointestinal series for the diagnosis of sigmoidovesical fistula: report of 3 cases].

Recently, sigmoidovesical fistula is not a rare disease as a result of the change of our food style and increase in the age ratio. However, in general, the preoperative image diagnosis is difficult. We have experienced three cases of sigmoidovesical fistula, examined by barium enema, cystography, upper gastrointestinal series, cystoscopy, colonic fiberscopy and computed tomography. The fistulas were identified preoperatively by the 24-hour delayed film of upper gastrointestinal series. By this method, the regions of sigmoidovesical fistula were identified, and the patients were operated. We concluded that the 24-hour delayed film in upper gastrointestinal series might be useful to diagnose the sigmoidovesical fistula.

Adult↗
PubMed1995

Suppressive effect of growth hormone on the expression of peroxisome proliferator-activated receptor in cultured rat hepatocytes.

The effect of growth (GH) and thyroid hormones (triiodothyronine, T3) on the expression of peroxisome proliferator-activated receptor (PPAR alpha) was examined using Northern blotting in primary cultures of rat hepatocytes. Exposure of the hepatocytes to GH at the concentrations of 5-500 ng/ml for 1 day decreased the steady state level of PPAR mRNA by 20-30% compared with the control. The decrease in the mRNA level reached about 50% after a 5-day exposure to 50 or 500 ng/ml GH. However, the PPAR mRNA level was increased by 30-50% in hepatocytes exposed to T3 at 30 or 300 nM. These findings suggest the suppression of PPAR expression as a possible mechanism for the GH-mediated suppression of the induction of peroxisomal beta-oxidation caused by peroxisome proliferators (PPs), whereas T3 may act in the other way to exert its suppressive effect on the PP induction of peroxisomal enzymes.

Animals↗
PubMed1995

Morphology of the dorsal lingual papillae in the lesser mouse deer, Tragulus javanicus.

The dorsal lingual papillae of the lesser mouse deer were studied morphologically using light and scanning electron microscopy. Four types of papillae, filiform, fungiform, vallate and foliate, were observed. Filiform papillae consisted of larger main papillae with smaller secondary papillae on their anterolateral aspects. Secondary papillae were well distributed over the anterior two-thirds of the tongue, but were very rare or absent in the posterior third. Fungiform papillae were distributed among the filiform papillae, being larger and more abundant on the tip of the tongue. Vallate papillae were round-flat or long-flat, surrounded by a prominent circular groove and a thin annular pad. An important finding was the presence of distinct and prominent foliate papillae on the posterolateral sides of the tongue. Keratinisation of the covering stratified squamous epithelium was relatively weak. Taste buds were observed in the epithelium of the fungiform, vallate and foliate papillae. The lingual papillae of the lesser mouse deer showed some characteristics that differed from those reported for domestic ruminants. These may be related to the feeding habits and the type of food eaten by this species.

Animals↗
PubMed1994

Specific binding of dehydroepiandrosterone sulfate to rat liver cytosol: a possible association with peroxisomal enzyme induction.

Incubation of [3H]dehydroepiandrosterone sulfate (DHEAS) with rat liver cytosol demonstrated its specific binding with a dissociation constant of 72 +/- 14 nM and a maximal binding capacity of 312 +/- 105 fmol/mg cytosol protein. The binding correlated with the amount of cytosol protein, and depended on time, temperature and pH, with equilibrium being reached after 6 h at 0 degrees C and pH 7.5. Boiling or treatment of the cytosol with proteases or sulfhydryl-blocking reagents affected the binding. The apparent molecular mass of the binding entity was estimated to be 160-230 kDa by HPLC gel filtration. In competitive binding studies, free steroids, including dehydroepiandrosterone (DHEA), sulfatase substrates and ligands of organic anion binders such as ligandin and fatty acid binding protein, had no effect on the [3H]DHEAS binding. Peroxisome proliferators also had no effect, except Wy-14,643. Competition with various steroids related to DHEAS revealed strict structural requirements for DHEAS binding, in which epiandrosterone sulfate was almost as effective as unlabeled DHEAS in inhibiting [3H]DHEAS binding. These findings indicated the presence of a binding protein highly specific to DHEAS in rat liver cytosol. The DHEAS binding in liver cytosol was 2-fold higher in male than in female rats. The cytosolic DHEAS binding was highest in the liver, followed by the kidney and heart. The possibility of association between the DHEAS binding and DHEA induction of peroxisomal beta-oxidation is discussed.

Animals↗
PubMed1994

Differences in immunomodulating effects between wild and cultured Panax ginseng.

The different effects between wild and cultured Panax ginseng on immunological activity were investigated. The extracts of hot water soluble fraction from wild Panax ginseng showed the mitogenic activity to lymphocytes but that from cultured Panax ginseng did not. The mitogenic activity of wild Panax ginseng (100 micrograms/well) was almost equal to Concanavalin A (0.1 microgram/well) which was well-known as one of T cell mitogens. The percentages of Thy 1.2-(pan T cells), L3T4-(helper T cells) and Lyt2-(cytotoxic T cells) positive cell population were significantly increased in the mice orally administered hot water soluble fraction from wild Panax ginseng as compared to control by 31.2, 17.9 and 30.1 percent, respectively.

Adjuvants, Immunologic↗
PubMed1994

Tremor and zitter, causative mutant genes for epilepsy with spongiform encephalopathy in spontaneously epileptic rat (SER), are tightly linked to synaptobrevin-2 and prion protein genes, respectively.

Spontaneously epileptic rat (SER) is a homozygote for both tremor (tm) and zitter (zi) genes and exhibits epilepsy-like seizures and spongiform encephalopathy. Genetic linkage analyses revealed that the tm and zi loci were tightly linked to the synaptobrevin-2 (Syb2) on chromosome 10 and the prion protein (Prnp) on chromosome 3, respectively. The genomic DNA sequences of Syb2 of the tm/tm (TRM) rats and exon 2 of the Prnp of the zi/zi (ZI) rats were identical to those of a control rat strain WTC. In addition, no difference was detected for expression of the Syb2 and Prnp on the Northern blot analyses of TRM, ZI and WTC brain, suggesting that the Syb2 and Prnp genes are not the tm and zi, respectively. The assignments of tm and zi to rat chromosome 10q24 and 3q35, however, will be the first step towards the positional cloning of the genes.

Animals↗