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Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 289 records · Page 16Linked to original sources
PubMed1992

A light-microscopic immunocytochemical study of the endocrine pancreas in the Australian fat-tailed dunnart (Sminthopsis crassicaudata).

The endocrine pancreas of the Australian fat-tailed dunnart (Sminthopsis crassicaudata) was investigated by means of immunocytochemistry using the avidin-biotin-peroxidase technique. This was a light microscopic study using this established technique and has not been previously investigated. Serial paraffin sections were stained individually with primary antibodies for anti-porcine glucagon, anti-beef pork insulin, anti-human somatostatin, and anti-avian pancreatic polypeptide (APP), anti-bovine pancreatic polypeptide (BPP), anti-serotonin, anti-porcine motilin, showing the same islet. Cells immunoreactive to porcine glucagon, porcine insulin, human somatostatin, APP, BPP were found in endocrine islets, but BPP and APP also appear to be scattered amidst the exocrine portion. Immunoreactive cells were not observed with serotonin and anti-porcine motilin. All controls were negative. These results in the dunnart pancreas has shown four types of pancreatic endocrine cells. It has also shown that the structure of PP may more closely resemble BPP than APP. This study can be related to studies in echidnas (Tachyglossus aculeatus) and Australian possum (Trichosurus vulpecula). This is a part of an immunocytochemical study investigating the endocrine pancreas in Australian mammals.

Animals↗
PubMed1991

Assay of fatty acid omega-hydroxylation using high-performance liquid chromatography with fluorescence labeling reagent, 3-bromomethyl-7-methoxy-1,4-benzoxazin-2-one (BrMB).

A sensitive nonradioisotopic method is reported for measuring microsomal lauric acid omega-hydroxylation activity. The assay is based upon separation and detection of 12-hydroxylauric acid formed by means of high-performance liquid chromatography following fluorescence labeling of the carboxyl group with 3-bromomethyl-7-methoxy-1,4-benzoxazin-2-one (BrMB). The use of 10-hydroxycapric acid as an internal standard affords the accurate and reproducible assay. The differential effect of dehydroepiandrosterone, a peroxisome proliferator, on the omega-hydroxylation activity in the liver and kidney of rats is also reported.

Animals↗
PubMed1991

Characteristics of muscarinic cholinergic, gamma-aminobutyric acid(A) and phencyclidine receptors in spontaneously epileptic rats; in vitro quantitative autoradiographic analysis.

Characteristics of muscarinic cholinergic (mACh), gamma-aminobutyric acid(A) (GABAA) and phencyclidine (PCP) receptors in the spontaneously epileptic rats (SER), which exhibit both absence-like seizures and tonic convulsion, were examined using in vitro quantitative autoradiography. Computer analysis using autoradiographic technique revealed that the amount of the specific binding of [3H]quinuclidinyl benzilate (QNB) to mACh receptors in the striatum of SER was more than that of zitter rats, not exhibiting both seizures and convulsion. However, the specific bindings of [3H]muscimol and [3H]N-(1-[2-thienyl]cyclohexyl)3,4-piperidine (TCP) to GABAA and PCP receptors, respectively, of SER were not different from those of zitter rats in various regions tested. These results suggest that hyperfunction of mACh receptors in the striatum is involved in the appearance of absence-like seizures and tonic convulsion of SER.

Animals↗
PubMed1991

Characteristics of dehydroepiandrosterone as a peroxisome proliferator.

Treatment of rats with dehydroepiandrosterone (300 mg/kg body weight, per os, 14 days) caused a remarkable increase in the number of peroxisomes and peroxisomal beta-oxidation activity in the liver. The activities of carnitine acetyltransferase, microsomal laurate 12-hydroxylation, cytosolic palmitoyl-CoA hydrolase, malic enzyme and some other enzymes were also increased. The increases in these enzyme activities were all greater in male rats than in female rats. Immunoblot analysis revealed remarkable induction of acyl-CoA oxidase and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme in the liver and to a smaller extent in the kidney, whereas no significant induction of these enzymes was found in the heart. The increase in the hepatic peroxisomal beta-oxidation activity reached a maximal level at day 5 of the treatment of dehydroepiandrosterone and the increased activity rapidly returned to the normal level on discontinuation of the treatment. The increase in the activity was also dose-dependent, which was saturable at a dose of more than 200 mg/kg body weight. All these features in enzyme induction caused by dehydroepiandrosterone correlate well with those observed in the treatment of clofibric acid, a peroxisome proliferator. Co-treatment of dehydroepiandrosterone and clofibric acid showed no synergism in the enhancement of peroxisomal beta-oxidation activity, suggesting the involvement of a common process in the mechanism by which these compounds induce the enzymes. These results indicate that dehydroepiandrosterone is a typical peroxisome proliferator. Since dehydroepiandrosterone is a naturally occurring C19 steroid in mammals, the structure of which is novel compared with those of peroxisome proliferators known so far, this compound could provide particular information in the understanding of the mechanisms underlying the induction of peroxisome proliferation.

Animals↗
PubMed1991

Inhibition by thyrotropin-releasing hormone of epileptic seizures in spontaneously epileptic rats.

The effects of thyrotropin-releasing hormone (TRH) were investigated on absence-like seizures, which are characterized by the sudden appearance of 5-7 Hz spike-wave-like complexes in the cortical and hippocampal EEG, and on tonic convulsions of spontaneously epileptic rats (SER; zi/zi, tm/tm), a double mutant obtained by mating zitter homozygote (zi/zi) with tremor heterozygote rats (tm/+). TRH (5 and 10 mg/kg i.v.) inhibited the appearance of both absence-like seizures and tonic convulsions of SER without inducing obvious changes in the background EEG. The inhibitory effects were seen 5-20 min after injection of 10 mg/kg TRH and were antagonized by pretreatment with haloperidol (0.5 and 1.0/kg i.p.), although haloperidol alone did not affect the seizures. These results suggest that TRH has an antiepileptic effect in the genetically defined animal model, SER, and that the effect is mediated by the central dopaminergic system.

Animals↗
PubMed1991

Characteristics of induction of peroxisomal fatty acid oxidation-related enzymes in rat liver by drugs. Relationships between structure and inducing activity.

To clarify the mechanism of induction of hepatic peroxisome-associated enzymes by drugs, we examined the interrelationship between the structures of fifteen drugs of two types (phenoxyacetic acid derivatives and perfluorinated compounds) and their inducing activities. Male Wistar rats were given the drugs at 150 mg/kg body weight daily for 2 weeks, and then hepatic activities of fatty acid metabolism-related enzymes were determined. The activity of the cyanide-insensitive fatty acyl-CoA oxidizing system located in peroxisomes was increased significantly in the following order: 2,4,5-trichlorophenoxypropionic acid (12.5-fold) greater than 2,4-dichlorophenoxypropionic acid (6.6-fold) greater than clofibrate (4.5-fold) greater than 2-methyl-4-chlorophenoxyacetic acid (2.6-fold) greater than 2,4,5-trichlorophenoxyacetic acid (2.5-fold) greater than p-chlorophenoxypropionic acid (2.4-fold) greater than 2,4-dichlorophenoxyacetic acid (1.7-fold). Treatment with perfluorinated compounds, perfluorobutyric acid, perfluorooctanoic acid, perfluorodecanoic acid and perfluorooctanol, also induced the activity by 2-, 4.3-, 3.1- and 2.0-fold respectively. The profile of the induction of carnitine acetyltransferase by these compounds was quite similar to that of cyanide-insensitive fatty acyl-CoA oxidizing system. Lipophilicity of these drugs was determined by the octanol-water partition method. Among these drugs, 2,4,5-trichlorophenoxypropionic acid showed the largest octanol/water partition coefficient (log P = 0.39). These results show a strong correlation among the number of chlor-substitutions on the phenyl moiety, the methyl-group on the alpha position of the acetic acid moiety, lipophilicity and the inducibility of peroxisomal fatty acid oxidation-related enzymes.

Animals↗
PubMed1991

Trajectory of spinocerebellar fibers passing through the inferior and superior cerebellar peduncles in the rat spinal cord: a study using horseradish peroxidase with pedunculotomy.

The course of spinocerebellar fibers in the rat spinal cord was investigated by injecting horseradish peroxidase into the cerebellar anterior vermis after complete transection of the left inferior and right superior cerebellar peduncles. By this procedure, fibers passing via the inferior cerebellar peduncles (icp-fibers) were labeled retrogradely on the right side of the spinal cord, whereas fibers passing via the superior cerebellar peduncles (scp-fibers) were labeled on the left side. Crossed icp-fibers were located diffusely in the anterior and lateral funiculi in the sacral to lower lumbar segments. They gradually migrated laterally and dorsally in these funiculi and received many uncrossed icp-fibers moving laterally in the lateral funiculus from the gray substance in the upper lumbar to lower thoracic segments. These mixed fibers shifted more dorsally and laterally in the anterior and lateral funiculi to aggregate in the narrow peripheral zone of the lateral funiculus in the upper thoracic and lower cervical segments, and received many crossed fibers in the upper cervical segments. There were more icp-fibers than scp-fibers through the spinal cord. However, the extent of scp-fibers in the anterior and lateral funiculi was essentially the same as that for icp-fibers, except that a few scp-fibers were found in the dorsolateral marginal zone of the lateral funiculus. It has been generally accepted that the dorsal spinocerebellar tract ascends in the dorsal half of the lateral funiculus and enters the cerebellum via the inferior cerebellar peduncle, whereas the ventral spinocerebellar tract ascends in the ventral half of it and takes the superior cerebellar peduncle route. The results of this study suggest that it is necessary to revise this concept.

Animals↗
PubMed1991

Muscular architecture in the omasal laminae of cattle and sheep.

The muscular architecture of the bovine omasal laminae was examined. The omasal laminae had three thin smooth muscle layers which consisted of an intermediate layer and two lateral layers. The muscle bundles of the intermediate layers ran radially in the laminae and those of the two lateral layers ran parallel to the free border of the laminae. At the free border, three types of the muscular architecture were observed. In a histological study, the muscle bundles of the intermediate layer penetrated into the connective tissue around and smooth muscle fasciculi of the inner layer of the tunica muscularis of the omasal wall and attached to the bundles of both the inner layer and of the outer layer of the tunica muscularis. These results indicate that a re-evaluation of the muscular architecture in the omasal laminae is required to facilitate better understanding of the omasal morphology and physiology.

Animals↗
PubMed1991

Specificity of the sex-influenced esterase (ES-SI) isozyme in rat liver.

A carboxylesterase which shares common antigenicity with sex-influenced esterase (ES-SI) was found in both the male and the female liver of the rat but not in the following tissues: erythrocyte, heart, kidney, lung, spleen, small intestine, testis, thymus, and lymph node. Subcellular fractionation showed the esterase localizes in the microsome-rich fraction. The strain distribution of the presence or absence of the esterase in inbred rats was identical to that of ES-SI, although in adult males a considerable amount of the esterase exists, unlike ES-SI. The esterase had a higher isoelectric point than ES-SI but after neuraminidase treatment the difference disappeared, suggesting that the esterase has a sialic acid moiety. Because this esterase has different properties from those previously reported, it is proposed that it is designated liver-ES-SI. The common antigenicity and similar strain distribution between ES-SI and liver-ES-SI suggest that liver-ES-SI is a precursor molecule of ES-SI and therefore the two esterases are products of a single gene.

Animals↗
PubMed1991

Semidominant expression of absence-like seizure in tremor rats.

Tremor rats (tremor homozygous rats) exhibit spontaneous absence-like seizure, which is characterized by a sudden immobility with staring and the appearance of 5- to 7-Hz spike and wave complexes in cortical and hippocampal electroencephalogram (EEG). In this study, we examined the development of the seizure and the mode of inheritance. All tremor homozygous and heterozygous rats exhibited the seizure by 14 and 26 weeks of age, respectively. The frequency and total duration in tremor heterozygous rats were significantly lower in comparison with those in tremor homozygous rats. None of the seven tremor wild-type homozygous rats exhibited the seizure. In an EEG study of backcross progeny of (BN/fMaiKyo x tremor heterozygous rats)F1 (tm/+) x tremor heterozygous rats at 5 months of age, the ratio of rats with and without the seizure was 23:7 (chi 2 = 0.09 for 3:1 ratio). These results suggest that the absence-like seizure is semidominantly expressed, in contrast to other recessive mutant traits in tremor rats.

Animals↗
PubMed1991

Kanji words are easier to identify than katakana words.

The effects of script (kanji and katakana), lexicality (word and nonword), and string length (1, 2, and 4 characters) on the identification of briefly exposed kanji and katakana strings were examined. It was found that identifiability is far higher for kanji words than for katakana words, even though the former are visually more complex than the latter. However, the superiority of kanji completely disappeared in a nonword context, suggesting that it is not visual perceptibility that enhances identifiability of kanji words, but something else, perhaps inferability. Differing effects of visual complexity and form were also found. A theory that explains these results is presented.

Adult↗
PubMed1991

Benzodiazepine receptor binding in the spontaneously epileptic rat and its parent strains.

Central type benzodiazepine (BDZ) receptor binding in spontaneously epileptic rats (SER) and their parent strains, tremor rats and zitter rats, and Kyoto/Wistar rats were investigated. Significantly lower BDZ receptor densities (Bmax) and no differences in affinity (KD) were found in the hippocampus of the two epileptic strains, SER and tremor rats, in comparison with Kyoto/Wistar rats and zitter rats. This abnormality is considered to be due to a tremor gene and to be related to absence-like seizures in SER and tremor rats. A significant decrease of KD and an increase of Bmax in the brain stem were found in SER in comparison with Kyoto/Wistar rats. These changes may be due to a zitter gene, since zitter rats show the same tendency, and they may be related to tonic seizures in SER. Bmax was significantly increased in the cerebellum and hippocampus of the zitter rats, while KD was not changed, in comparison with Kyoto/Wistar rats and tremor rats. These changes may reflect the relatively selective loss of tissue lacking BDZ receptors or an upregulation in response to the loss of GABAergic neurons in zitter rats.

Animals↗
PubMed1991

The involvement of insulin in tryptamine-induced hypoglycemia in mice.

The effects of tryptamine on plasma glucose and serum insulin levels were studied in mice. Tryptamine elicited dose-dependent hypoglycemia and hyperinsulinemia in intact mice. In streptozotocin-diabetic mice, tryptamine did not change plasma glucose nor serum insulin levels. Tryptamine significantly inhibited glucose-induced hyperglycemia and enhanced insulin release elicited by glucose. These results indicate that tryptamine-induced hypoglycemia is brought on by its releasing effects of insulin.

Animals↗
PubMed1991

Activation of peripheral serotonin2 receptors induces hypothermia in mice.

The effects of peripherally administered serotonin (5-HT) on the rectal temperature were investigated. 5-HT i.p. induced a dose-dependent hypothermia in mice. The hypothermic effects of 5-HT were strongly antagonized by the 5-HT1 and 5-HT2 receptor antagonist methysergide and the 5-HT2 receptor antagonist ketanserin. However, the 5-HT1 receptor antagonist pindolol and the 5-HT3 receptor antagonist ICS 205-930 were without effect. In addition, the peripheral 5-HT2 receptor antagonist xylamidine strongly reduced 5-HT-induced hypothermia. These results indicate that the activation of the peripheral 5-HT2 receptors induces hypothermia, although the central 5-HT2 receptors have been suggested to relate to hyperthermia.

Animals↗
PubMed1991

Mechanisms of rejection during OKT3 therapy: propagation and characterization of CD3 resistant allospecific cytotoxic T cells from a rejecting liver allograft.

Allograft rejection remains the single largest impediment to success in the field of transplantation. While OKT3 therapy has proven to be a significant advancement, many grafts are still lost. Late treatment, subtherapeutic OKT3 levels, anti-OKT3 antibodies, and OKT3-induced class II antigen expression are possible explanations. To determine the mechanism of OKT3 resistant rejection we propagated and characterized infiltrating T cells from the biopsy of a liver transplant patient who was rejecting while on prophylactic OKT3. The T lymphocytes demonstrated allospecific proliferation and interleukin 2 (IL2) production and showed a high degree of cytolysis of donor splenocytes. CD3 epsilon monoclonal antibodies (Mab) in concentrations up to 100 micrograms/ml did not inhibit lysis. In contrast, T lymphocytes derived from rejecting allografts of patients receiving cyclosporine and prednisone were readily inhibited from killing by CD3 epsilon Mab at doses of 1 microgram/ml. Furthermore, allospecific proliferation and IL2 production were not inhibited in the OKT3-treated patient by the addition of CD3 epsilon MaB. Incomplete modulation of the CD3-TCR complex was noted after a 72-hr incubation with CD3 epsilon Mab. The T cells did demonstrate other intact CD3-mediated functions such as a rise in intracellular calcium and CD3-dependent cytotoxicity. These results should alert clinicians that CD3 resistant cytotoxic T cells can emerge during OKT3 therapy and may cause rejection. Immunotherapy that targets additional cell surface structures may be of benefit.

Antibodies, Monoclonal↗
PubMed1991

CNS pathology in the neurological mutant rats zitter, tremor and zitter-tremor double mutant (spontaneously epileptic rat, SER). Exaggeration of clinical and neuropathological phenotypes in SER.

The pathological alterations in the central nervous system (CNS) were examined in three kinds of mutant rat; the zitter (zi/zi; Zi), the tremor rat (tm/tm; Tm) and the spontaneously epileptic rat (SER) which is a double mutant carrying both zitter and tremor genes. Two major alterations demonstrated in these mutants were hypomyelination and vacuolation or spongy degeneration. Hypomyelination was observed predominantly in SER and to a lesser extent in Zi, and was accompanied by a redundant or aberrant myelin sheath formation in addition to a decreased number of myelinated fibres. This appeared to be related to the occurrence of tremor. There was no abnormality in the structure of the myelin lamellae and oligodendrocytes or any destruction of myelin sheaths by phagocytic cells. The number of radial components in CNS myelin was increased almost equally in Zi, Tm and SER. Vacuolation was prominent in SER and Tm, especially in the brainstem and thalamus. Zi also developed mild vacuolation with advancing age. Vacuolation seemed to be related to the epileptic phenomena in SER and Tm. Vacuoles consisted mainly of swollen astrocytic processes and enlargement of the extracellular space, as well as occasional enlargement of periaxonal spaces. Thus both pathological findings--the hypomyelination derived from the zitter mutation with tremor, and the vacuolation from the tremor mutation with epileptic symptoms--were mutually exaggerated in SER. It is postulated that the two different genetic loci with zi and tm mutations interact and synergistically reinforce each other both clinically and pathologically in SER.

Aging↗
PubMed1991

[Serotypes and antibiotic sensitivity of hemolytic streptococci isolated from clinical specimens in Hiroshima Prefecture, 1987-1989].

The grouping, the typing and the drug-sensibility of hemolytic streptococci isolated from the clinical specimens taken from 4 medical centers in Hiroshima Prefecture have been examined and reviewed during the past 3 years 1987-1989. The results were summarized in this report. 1. Of 1572 strains of hemolytic streptococci, 844 strains (53.7%) were group A; 539 strains (34.3%), group B; 14 strains (0.9%), group C; 82 strains (5.2%), group G; and 93 strains (5.9%), the others. We found that group A and group B were predominant, and the incidence rate of group B was higher than it used to be. 2. The prevalent types were T-4 (37.9%), T-1 (13.6%), T-12 (12.0%), and T-28 (10.7%) in group A, while Ia (26.2%), M9 (provisional type 18.4%), and III (14.5%) in group B. 3. As far as the detection data of each month is concluded, during the summer season we could hardly detect group A which peak of occurrence during the winter season. These findings were really consistent with the occurrence pattern of those patients who suffered from streptococcal infectious disease. But this occurrence pattern couldn't be found in group B. 4. In our study, the positive frequency was throat swab greater than urine greater than sputum greater than vaginal swab greater than pus greater than ear secretion in order. Group A was mainly isolated from throat swab, while group B, from several specimens including urine. 5. We found that there was a high drug-sensibility to the beta-lactam drugs in all strains except for 3 strains of group B which were resistant to CEX.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗