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Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 253 records · Page 14Linked to original sources
PubMed1993

Lack of stereoselectivity in rat liver peroxisomal enzyme induction by optically active phenoxyacetic acids.

To ascertain if there is stereoselectivity in peroxisomal proliferation induced by chiral peroxisome proliferators, induction by stereoisomers of 2-methyl-4'-chlorophenoxyacetic acid and 2-methyl-2-(2'-4'-dichlorophenoxy)acetic acid were studied in rat in vivo and in vitro with isolated rat hepatocytes. No significant differences in the inducing potencies of the stereoisomers of the above two phenoxyacetic acid derivatives were found for cyanide-insensitive fatty acyl-CoA oxidizing system, fatty acyl-CoA oxidase, carnitine acetyltransferase or carnitine palmitoyltransferase. There was also no significant difference in the degree of hepatomegaly or lipid-lowering effect between the isomers. The findings with cultured rat hepatocytes agreed with those of the studies in vivo.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

Genetic polymorphisms of salivary proteins in the rat.

Two genetic polymorphisms of salivary proteins were found by polyacrylamide gel electrophoresis among inbred strains of rats. Both proteins (RSP-1 and RSP-2) were inherited as a single autosomal trait. The loci were designated as Rsp-1 (rat salivary protein-1) and Rsp-2. Rsp-1 had two codominant alleles (Rsp-1a, Rsp-1b), and Rsp-2 had two alleles (Rsp-2a, and Rsp-2b); Rsp-2a was dominant over Rsp-2b. The Rsp-1 locus is not linked with the linkage groups (LGs) I, II, IV, V and the LGs containing Acp-2 and Pg-1. The Rsp-2 is not linked with the LGs I, II, V, X and the LGs containing Amy-1, Es-6 and Pg-1.

Alleles↗
PubMed1993

Heterogeneity of motilin-immunoreactive cells in the duodenum and pyloric region of several avian species.

Immunohistochemical characterizations of motilin-immunoreactive cells were examined in gastric and duodenal mucosae of nine species of birds from seven orders using five different region-specific motilin antisera. Motilin-immunoreactive cells appeared as open-type cells in the mucosal epithelium and showed varying immunoreactivities to antisera used in all the birds examined except for the cormorant and penguin, which did not show any kinds of immunoreactivity to motilin. Motilin-immunoreactive cells of the emu duodenum were detected by all the motilin-antisera used. The present results suggest that there is a wide range of heterogeneity between motilin molecules among avian species, or perhaps alternatively the existence of a family of motilin-like peptide. Furthermore, the present results should prove useful for a molecular biological study on the evolution of avian motilin.

Animals↗
PubMed1993

Substance P-immunoreactive neurons of the bovine forestomach mucosa: their presumptive role in a sensory mechanism.

Substance P-immunoreactive nerve fibers and cell bodies were examined in the forestomach mucosa of the calf and cow pretreated with colchicine, using thick (100 microns) floating sections. Intraepithelial nerve fibers were identified, appearing only rarely in the rumen and reticulum, and completely absent from the omasum. Nerve fibers were observed in the lamina propria of all the regions of the forestomach examined. A few thin nerve fibers were seen in the core of the ruminal papillae of the calf, whereas in the cow they appeared very coarse in nature. Flocculent and complicated nerve fiber networks were seen in the connective tissue of the reticular papillae. Mucosal nerve fibers formed a peculiar glomerulus-like architecture in the omasal papillae of the calf, while in the cow, the nerve fibers were largely restricted in distribution to the vicinity of the epithelium within the connective tissue pegs. Immunoreactive nerve cell bodies were found in the ruminal atrium, the dorsal sac and the ventral sac of the rumen of the calf and in the reticulum of both the calf and cow. Some of these neurons exhibited processes that appeared to course toward the papillae. In total, substance P-immunoreactive nerve fibers and cell bodies were more abundant in the calf than in the cow. These distributions demonstrate that the neural circuitry of the bovine forestomach contains substance P immunoreactivity in the mucosa as well as in the muscle layer, pointing to its possible importance in the regulation of the forestomach function. Substance P-immunoreactive nerve fibers were numerous in the reticular papillae of the calf and cow and in the omasal papillae of the calf. The positive fibers at these localities may act as mucosal receptors.

Aging↗
PubMed1993

An immunohistochemical survey of peptide-containing nerves in the copulatory apparatus of several male birds.

Distribution of peptide-containing nerves in male copulatory apparatus as well as rectal and cloacal ganglia were examined immunohistochemically in cock, guinea fowl, duck and muscovy duck. Neurofilament protein-immunoreactive nerves were also examined to investigate general distribution of nerves. Substance P (SP)-, vasoactive intestinal polypeptide (VIP)-, calcitonin gene-related peptide (CGRP)-, and neuropeptide Y (NPY)-immunoreactive (IR) nerves were detected in all four species of birds whereas leucine enkephalin (LENK)-IR nerves were detected only in duck and muscovy duck. In the rectal and cloacal ganglia, peptide-IR nerves were detected in varying degrees of abundance. Most noticeable distribution was found in the vascular body, where SP-IR nerve fibres were more abundant in duck and muscovy duck, VIP-IR fibres in muscovy duck and CGRP-IR fibres in duck, than in other regions and other species, respectively. A few peptide-IR nerve fibres were detected in other cloacal regions, although a peculiar pattern in distribution unique to a certain region could be not found. The present results suggest that the peptide-containing nerves participate in the regulation of tumescence, erection and detumescence of male copulatory apparatus of birds and their regulatory mechanisms are different depending on the species.

Animals↗
PubMed1993

An immunohistochemical study on the gastrointestinal endocrine cells of three honeyeaters: singing honeyeater (Meliphaga virescens), spiny-cheeked honeyeater (Acanthogenys rufogularis) and brown honeyeater (Lichmera indistincta).

The gastrointestinal endocrine cells of the singing honeyeater (Meliphaga virescens), spiny-cheeked honeyeater (Acanthogenys rufogularis) and brown honeyeater (Lichmera indistincta) were studied immunohistochemically with special reference to their degree of dependency upon nectar. The nine types of immunoreactive endocrine cells were detected in their gastrointestinal mucosa. Coexistence of motilin and serotonin in the same cells was confirmed in the pyloric region. In the duodenum and jejunum, a few peptide tyrosin tyrosin (PYY)-immunoreactive cells were detected. The clear difference in the distribution and frequency of the gastrointestinal endocrine cells among three types of honeyeaters, which differ in the degree of dependency upon the nectar, could not be confirmed. However, some differences were found that serotonin-, somatostatin- and gastrin-releasing peptide (GRP)-immunoreactive cells in the gizzard, gastrin-immunoreactive cells in the duodenum and jejunum, enteroglucagon-immunoreactive cells in the caeca and in the colon, and pancreatic glucagon-immunoreactive cells in the ileum of brown honeyeaters were more numerous (p < 0.05) than other two species.

Animals↗
PubMed1993

Transforming growth factor-beta in rat kidney during compensatory renal growth.

Transforming growth factor-beta (TGF-beta) inhibits the DNA synthesis and stimulates the alkaline phosphatase activity of cultured renal cortical tubular cells. When unilateral nephrectomy was performed, TGF-beta activity content gradually decreased in the remaining kidney. An immunohistochemical study of the remaining kidney after uninephrectomy, however, showed that the expression of TGF-beta increased by the third day after uninephrectomy in the proximal tubular cells and an autoradiographic study revealed that TGF-beta expressing tubular cells were different from proliferating cells during compensatory renal growth. These results indicate that the total renal TGF-beta content decreases after uninephrectomy, while the expression of TGF-beta in the proximal tubular cells may increase and act as a brake for compensatory renal hyperplasia.

Adaptation, Physiological↗
PubMed1993

[Clinical application of vitamin A, D and E against malignant tumor in human].

A great number of epidemiologic studies over the last decade have found that vitamin A, D and E are associated with a reduced risk for malignant tumors in human, though these high levels in blood do not always establish the low risk of a variety of malignant tumors. Consequently, either micronutrient supplementation or/and food fortification are going to be recommended as a prevention strategy of malignant tumors to the general population. On the other hand, concerning the clinical application of these vitamins in the treatment for malignant tumors, most recently, active forms of vitamin A and D are said to be effective in some leukemias. Especially, the administration of all-trans retinoic acid in acute promyelocytic leukemia patients has been established to be more effective and safer than conventional chemotherapies to obtain complete remission. In reviewing these studies, more detailed elucidation in clinical usefulness of these vitamins and as their chemoprevention must await further investigations.

Humans↗
PubMed1993

Histochemical localization of glycosaminoglycans in the omasal papillae of sheep.

Histochemical localization of the glycosaminoglycans in the omasal laminae were examined at light and electron microscopic levels. The core region of the omasal papillae was stained strongly with alcian blue at pH 2.5 and 1.0. The staining was degraded moderately and completely when tissue sections were pretreated with mild and active methylation, respectively. Alcianophilia was moderately decreased with saponification. Furthermore, enzymatic digestion procedures showed that these alcianophilic substances contained a large amount of hyaluronic acid and chondroitin sulphate. Ultrastructurally, a spider web-like structure was widely distributed among the spindle-shaped fibroblast-like cells and fibrous networks of collagen and elastin. These results suggest that the core region of the omasal papillae not only acts as a physical buffer resisting the local pressure from the lumen, but may also influence material transport through the omasal mucosa.

Animals↗
PubMed1992

Antiepileptic effects of CNK-602A, a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats.

The effects of CNK-602A (N-[(6-methyl-5-oxo-3-thiomorpholinyl) carbonyl]-L-histidyl-L-prolinamide), a novel thyrotropin-releasing hormone related analog, were investigated on absence-like seizure and tonic convulsion in the spontaneously epileptic rat (SER), which is a genetically defined double-mutant. When CNK-602A of 0.2-1 mg/kg was given intravenously to the animal, there were no changes in the background EEG except for an increase in low-voltage fast waves concomitant with behavioral alertness. However, CNK-602A suppressed absence-like seizure and tonic convulsion in a dose-dependent manner for over 1 h. These antiepileptic effects of CNK-602A on both seizures were antagonized by pretreatment with haloperidol (1 mg/kg, i.p.). It was found, using a brain in vivo microdialysis method, that CNK-602A at a dose of 1 mg/kg, which inhibits the seizures, increased the release of dopamine in the caudate nucleus. These results suggest that CNK-602A inhibits the seizures of SER in a similar manner to thyrotropin-releasing hormone (TRH), probably by increasing the release of dopamine in the central nervous system. In addition, the antiepileptic effects of CNK-602A were more potent and lasted longer than those of TRH.

Animals↗
PubMed1992

Induction of peroxisomal beta-oxidation enzymes by dehydroepiandrosterone and its sulfate in primary cultures of rat hepatocytes.

Treatment of cultured rat-hepatocytes with 50 microM dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) for up to 5 days resulted in a progressive increase in peroxisomal beta-oxidation and carnitine acetyltransferase activity. After 5 days, the increases in activity were 2.6- and 4.8-fold for peroxisomal beta-oxidation and 11.7- and 17.1-fold for carnitine acetyltransferase over the initial activity, in DHEA- and DHEAS-treated cells, respectively. The stimulation of the activity of these enzymes by the respective agents was dose-related; it was maximum with 50 to 100 microM DHEA and 50 to 250 microM DHEAS, although DHEAS was more effective for stimulation than DHEA. Western blot analyses revealed the induction of acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme and carnitine acetyltransferase in the treated cells. Moreover, induction of fatty acid omega-hydroxylase proteins (P-450IVAS) was also revealed. These results indicate that DHEA and DHEAS act directly on hepatocytes. The induction of hepatic peroxisomal beta-oxidation enzymes and several other enzymes in rats administered with DHEA could be accounted for, at least in part, by the direct action of DHEA and its sulfate-conjugate (DHEAS) on liver cells.

Animals↗
PubMed1992

Hyperglucagonemia induced in mice by tryptamine: involvement of the peripheral 5-HT2 receptors.

The effects of an indoleamine, tryptamine, on plasma glucagon levels were investigated in mice. Tryptamine induced dose-related increases in plasma glucagon levels. The hyperglucagonemia effects of tryptamine were completely antagonized by methysergide and ketanserin which have a high affinity to 5-HT2 receptors. In addition, the peripheral 5-HT2 receptor antagonist, xylamidine, also strongly inhibited tryptamine-induced hyperglucagonemia. Our results indicate that the peripheral 5-HT2 receptors mediate the increase in plasma glucagon levels induced by tryptamine and that these receptors may have a role in the control of glucagon secretion.

Animals↗
PubMed1992

A specific method for determination of peroxisomal beta-oxidation activity in cultured human skin fibroblasts using a specific substrate, C9: a possible application for screening of peroxisomal disorders.

We developed a specific method for direct determination of peroxisomal beta-oxidation activity in cultured human skin fibroblasts. When control fibroblasts were incubated with N-(alpha-methylbenzyl)azelaamic acid (C9), a specific peroxisomal substrate, C5 and C7, the chain-shortened products, were detected with cell concentration and incubation time dependencies and no other products including C3 were detected. In glutaric aciduria type I and type II fibroblasts, the formation rates of C2 units liberated from C9 were almost similar to that in control cells. In contrast to these cell types, the fibroblasts from patient of Zellweger syndrome, in which peroxisomal beta-oxidation was impaired, showed no conversion of C9 to C5 and C7. The lack of the C2 units liberation in Zellweger fibroblasts was not due to an impairment of mitochondrial beta-oxidation and/or activation of C9 to C9-CoA derivative for subsequent beta-oxidation reaction, but rather, appeared to be due to the specific defect of peroxisomal beta-oxidation system. These results indicate that C9 is a useful substrate for the estimation of peroxisomal beta-oxidation activity in cultured human skin fibroblasts.

Cells, Cultured↗
PubMed1992

Comparison of the inducing effect of dehydroepiandrosterone on hepatic peroxisome proliferation-associated enzymes in several rodent species. A short-term administration study.

The in-vivo effect of dehydroepiandrosterone (DHEA) on hepatic enzyme activities of rats, mice, hamsters and guinea pigs was investigated. After DHEA treatment (300 mg/kg body weight, per os, 14 days), the activities of peroxisomal beta-oxidation, catalase, carnitine acetyltransferase, carnitine palmitoyltransferase, lauric acid omega-hydroxylation, 1-acylglycerophosphocholine acyltransferase, malic enzyme and cytosolic palmitoyl-CoA hydrolase were increased in rats and in mice although to a smaller extent in the latter. These enzyme activities, however, were unchanged in hamsters with the exception of omega-hydroxylation (2.5-fold increase) and 1-acylglycerophosphocholine acyltransferase (2.0-fold increase). No significant changes were observed in any of these enzyme activities in guinea pigs. Immunoblot analysis confirmed the induction of peroxisomal acyl-CoA oxidase and enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional enzyme in rats and mice. These results indicate that there are species differences in the inducing effect of DHEA on hepatic peroxisome proliferation-associated enzymes, which correlates well with the enzyme induction observed with other peroxisome proliferators.

Animals↗
PubMed1992

Effects of growth hormones on bone formation and resorption in rainbow trout (Oncorhynchus mykiss), as examined by histomorphometry of the pharyngeal bone.

Effects of salmon and eel growth hormones (GHs) on bone metabolism in rainbow trout (Oncorhynchus mykiss) were studied using histomorphometry of their pharyngeal bones. When salmon GH (sGH) was injected intraperitoneally at a dose of 0.01 or 0.1 microgram/g/week for 10 times into fed trout, body growth in both length and weight was accelerated. Formation and resorption of bone were enhanced only by the higher dose of sGH. When a cholesterol pellet containing recombinant eel GH (reGH-pellet) was implanted subcutaneously into starved trout for 1 week (37 micrograms reGH/18 g fish), formation and resorption of bone increased, although activity of bone formation was low. The results indicate that the GHs increased both formation and resorption of bone, regardless of the nutritional status of the fish.

Animals↗
PubMed1992

Why are kana words named faster than kanji words?

Feldman and Turvey (1980) found that colors conventionally written in kanji (a logo-graphic script) are named slower than are the unconventional kana (a syllabic script) transcriptions of the kanji color words. This surprising finding was attributed to the closer relation of kana to phonology, which is consonant with the general dual-route theory. However, the present study has shown that kanji numerals are named faster than are the corresponding kana numerals. A hypothesis involving selection difficulty inherent in most kanji is presented to explain those apparently conflicting results. Some implications for further research on the kanji versus kana issue are also discussed.

Adult↗