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Biomedical subjects

A Ohta

Publications and source records attributed to A Ohta.

At least 181 records · Page 10Linked to original sources
PubMed1995

Effects of fructooligosaccharides on the absorption of iron, calcium and magnesium in iron-deficient anemic rats.

We investigated the effects of fructooligosaccharides (FO)-feeding on the absorption of iron (Fe), calcium (Ca) and magnesium (Mg) and on the biochemical parameters in Fe-deficient anemic rats. Fe-deficient anemic rats were made by feeding an Fe-deficient diet for 3 weeks. Then these Fe-deficient rats were fed an experimental diet that contained one of two levels of Fe (15 or 30 mg/kg diet), in the form of ferric pyrophosphate, and one of two levels of FO (0 or 50 g/kg diet) for 2 weeks. After the rats were fed these experimental diets, FO-feeding increased the hematocrit ratio, the concentration of hemoglobin and the hemoglobin regeneration efficiency during the first week. Also, the apparent absorption of Fe was increased by FO-feeding. The levels of Fe in the diet did not affect the absorption of Ca and Mg. However, FO-feeding increased the absorption of Ca and Mg. FO-feeding lowered the pH and raised the solubility of Fe, Ca and Mg in the cecal contents, suggesting that those increasing effects of FO-feeding on absorption of these minerals is correlated with fermentation of FO in the large intestine, namely, the cecum and colon. We concluded that FO-feeding improved recovery from anemia and increased the absorption of Fe, Ca and Mg in Fe-deficient anemic rats.

Absorption↗
PubMed1995

Mechanism of the hyperthermic effect of the novel thyrotropin-releasing hormone analogue Na-((1S,2R)-2-methyl-4-oxocyclopentylcarbonyl)-L-histidyl-L- prolinamide monohydrate in mice with reserpine-induced hypothermia.

To investigate the mechanism of the antagonistic effect of Na-((1S,2R)-2-methyl-4-oxocyclopentylcarbonyl)-L-histidyl-L-prolin amide monohydrate (CAS 131404-34-7, JTP-2942) on reserpine-induced hypothermia, the role of the autonomic nervous system, adrenal gland, and thyroid gland regarding the effects of JTP-2942 has been studied in mice. Both phenoxybenzamine and propranolol significantly attenuated the hyperthermic effect of JTP-2942 on reserpine-induced hypothermia, although neither drug caused complete inhibition. A high dose of hexamethonium also significantly antagonized the hyperthermic effect of JTP-2942. The hyperthermic effect of JTP-2942 was almost abolished by adrenal demedullation. In mice with thiouracil-induced hypothyroidism, both thyrotropin-releasing hormone (TRH) and JTP-2942 significantly increased the rectal temperature. However, the increase induced by TRH was smaller in hypothyroid mice than in control mice, while the temperature increase induced by JTP-2942 was similar in both hypothyroid and control mice. These results suggest that the hyperthermic effect of JTP-2942 is mainly mediated by the adrenal gland and the autonomic nervous system. In addition, the hypothalamic-pituitary-thyroid axis does not regulate the hyperthermic effect of JTP-2942, unlike that of TRH.

Adrenal Medulla↗
PubMed1995

Transport and metabolism of glutathione isopropyl ester in cerebrospinal fluid.

The transport of glutathione (GSH) or glutathione isopropyl ester (GSH isopropyl ester) to the cerebrospinal fluid (CSF) in rats was estimated by levels of GSH or GSH isopropyl ester and their metabolites in CSF 30 min after the intravenous administration of GSH or GSH isopropyl ester (300 mg/kg). Although the CSF uptake of GSH isopropyl ester was almost equal to that of GSH as evidenced by about a two-fold increase in the amount of non-protein sulfhydryl groups in CSF, the sum of GSH isopropyl ester and GSH concentrations in the CSF after GSH isopropyl ester treatment was increased by 32% compared with saline-treated controls. On the other hand, treatment with GSH had no significant increase in GSH levels in CSF but increased its metabolite levels, such as cysteinyl-glycine and cysteine. GSH isopropyl ester was less metabolized than GSH. GSH isopropyl ester had low affinity to purified gamma-glutamyl transpeptidase, a key enzyme for metabolism of GSH in the choroid plexus, supporting the finding that GSH isopropyl ester is more stable than GSH in CSF. These results are compatible with our previous report (Yamamoto et al. (1993) showing that the protective action of GSH isopropyl ester against cerebral ischemia was greater than that of GSH in rats. GSH isopropyl ester may be a useful agent which protects the brain from the damage associated with oxygen-related toxicities by increasing GSH levels in the CSF.

Animals↗
PubMed1994

Loss of phosphatidylserine synthesis results in aberrant solute sequestration and vacuolar morphology in Saccharomyces cerevisiae.

Null cho1 mutants of Saccharomyces cerevisiae are incapable of phosphatidyl-serine synthesis. They were more susceptible than wild-type strains to 100 mM CaCl2, 3 mM ZnCl2 or 1 mM MnCl2, but not to MgCl2 nor KCl. They were also susceptible to high concentrations of basic amino acids, L-lysine and L-arginine, and to an L-lysine analog, S-2-aminoethyl-L-cysteine. Their vacuolar pools of amino acids, especially those of basic ones, were decreased. Pigmentation of cho1 ade2 double mutants was obscured and vacuoles of cho1 mutants were considerably fragmented. These indicate that phosphatidylserine plays vital roles in normal vacuolar function and morphogenesis.

CDPdiacylglycerol-Serine O-Phosphatidyltransferase↗
PubMed1994

The prosequence of Rhizopus niveus aspartic proteinase-I supports correct folding and secretion of its mature part in Saccharomyces cerevisiae.

Extracellular Rhizopus niveus aspartic proteinase-I (RNAP-I) was secreted effectively by Saccharomyces cerevisiae when RNAP-I with its preprosequence was synthesized in this organism (Horiuchi, H., Ashikari, T., Amachi, T., Yoshizumi, H., Takagi, M., and Yano, K. (1990) Agric. Biol. Chem. 54, 1771-1779). Certain deletions (delta pro, delta 1, delta 2), and amino acid substitutions (M1) in the prosequence blocked secretion of RNAP-I, although the protease protection assay revealed that even delta pro could be translocated across the membrane of the endoplasmic reticulum. When delta pro or M1 was synthesized simultaneously with the wild-type preprosequence in S. cerevisiae, secretion of RNAP-I was recovered. Therefore, the physical linkage of the prosequence to the mature region is not a prerequisite for secretion of active RNAP-I. Purified RNAP-I with the prosequence once denatured in 6 M guanidine HCl could be renatured and activated to have its enzymatic activity by removing guanidine HCl in vitro, but RNAP-I without the prosequence could not. Furthermore, the wild-type prosequence helped the recovery of the activity of the denatured RNAP-I in trans, but the prosequences of M1 with which secretion of RNAP-I was not observed in vivo, did not. From these results we concluded that the prosequence of RNAP-I supports correct folding of RNAP-I in the endoplasmic reticulum lumen and its subsequent secretion in S. cerevisiae. The functional role of the prosequence of an aspartic proteinase was elucidated.

Amino Acid Sequence↗
PubMed1994

Molecular diversity of three S-allele cDNAs associated with gametophytic self-incompatibility in Lycopersicon peruvianum.

We isolated S allele-associated cDNA clones from each of the stylar cDNA libraries of Lycopersicon peruvianum of two different S genotypes (S12Sb and S13Sc) with S11Sa allele-associated cDNA (LPS11) as a probe. The longest cDNA clones, designated LPS12 and LPS13, which were 779 bp and 853 bp in length, contained open reading frames of 189 and 210 amino acids, respectively. The three S allele-associated cDNAs (LPS11, LPS12, and LPS13) did not cross-hybridize to each other under highly stringent condition by northern blot analysis. Their average identity to Nicotiana alata S-proteins so far was 49%. The fragments corresponding to LPS11 or LPS12 cosegregated with their respective S alleles in genetic crosses. From these results, we conclude that the three cloned cDNAs were derived from the three different S alleles of L. peruvianum.

Alleles↗
PubMed1994

Cloning and characterization of two 3-phosphoglycerate kinase genes of Rhizopus niveus and heterologous gene expression using their promoters.

Two 3-phosphoglycerate kinase genes (pgk1 and pgk2) were cloned from Rhizopus niveus. It was deduced that both pgk genes have two introns. They have open reading frames of 1,355 bp and 1,356 bp, and code for proteins of 417 and 416 amino acids, respectively. The first introns of both genes are located at similar positions as those of pgk genes from other fungi based on the deduced amino-acid sequences of PGK proteins. The position of their second introns was similar to that of the seventh intron of the human pgk gene. The deduced amino-acid sequences of PGK proteins show high identity (64.8-72.2%) to those of PGKs of other filamentous fungi. When the promoters of each of the pgk genes were fused to the E. coli beta-glucuronidase (GUS) gene and introduced into R. niveus, significant GUS activities were detected in the cell lysates of the transformants, suggesting that GUS protein was expressed under the control of both pgk gene promoters in R. niveus. GUS activity was induced by glucose but not by glycerol, indicating that expression of R. niveus pgk genes was regulated by the carbon source.

Bacterial Proteins↗
PubMed1994

Expression of an endogenous and a heterologous gene in Candida maltosa by using a promoter of a newly-isolated phosphoglycerate kinase (PGK) gene.

A gene encoding phosphoglycerate kinase (PGK) was isolated from the genomic library of C. maltosa to construct an expression vector for this yeast. The PGK gene had an open reading frame of 1,251 base pairs encoding approximately 47-kDa polypeptide of 417 amino-acid residues. Expression of this gene assayed by Northern-blot analysis was significantly induced in cells grown on glucose but not in cells grown on n-tetradecane, n-tetradecanol, or oleic acid. By using the promoter region of this gene, an expression vector (termed pMEA1) for C. maltosa was constructed and expression of an endogenous gene (P450alk1 encoding one of cytochrome P450s for n-alkane hydroxylation in C. maltosa) and a heterologous gene (LAC4 encoding Kluyveromyces lactis beta-galactosidase) was tested. Expression of P450alk1 gene was confirmed at both mRNA and protein levels. LAC4 gene expression was confirmed by determining beta-galactosidase activity. The activity in cells grown on various carbon sources correlated very well with the expression levels of PGK mRNA in these cells.

Alkanes↗
PubMed1994

New operative method for tracheal compression in congenital heart disease.

A new technique is described for repairing tracheal compression caused by ascending aorta associated with corrected transposition of the great arteries and pulmonary atresia in a 113-day-old infant. Surgical repair for the tracheal compression was accomplished by suspending the pericardium around the aortic arch to the underside of the sternum. This method seems to be useful for some patients with tracheal compression caused by the ascending aorta.

Airway Obstruction↗
PubMed1994

Localization of atrophy-prone areas in the aging mouse brain: comparison between the brain atrophy model SAM-P/10 and the normal control SAM-R/1.

Mouse inbred strain "SAM-P/10" (Senescence Accelerated Mouse) is a model of age-related brain atrophy. In this strain there is an earlier and more severe age-related deterioration in the conditional avoidance learning than the normal control inbred SAM-R/1 strain. The present study analysed age-related changes in brain area size using a computerized morphometric method. The region most vulnerable to age-related atrophy in SAM-P/10 was the frontal region of the cerebral cortex, including the prefrontal cortex. Other neocortical regions underwent diffuse atrophy. Posterior piriform cortex, entorhinal cortex, anterior olfactory nucleus, amygdala, caudate-putamen, nucleus accumbens and cerebellar cortex were atrophy-prone regions. The septum also underwent atrophy but other basal forebrain structures were intact. The hippocampus, diencephalon and brainstem structures showed no atrophic change. White matter structures did not change in size with aging except for the forceps minor of the corpus callosum, which showed age-related atrophy. On the contrary, SAM-R/1 showed a significant age-related atrophy only in a restricted part of the cerebral cortex, mainly in the parietal region. Other cortical regions, subcortical structures, diencephalon, brainstem structures, cerebellum and white matter were atrophy-resistant in SAM-R/1. The prefrontal cortex, entorhinal cortex, piriform cortex and striatum are closely interconnected and also connect with the amygdala which plays a key role in conditioning in the rodent. Age-related atrophy in all these structures in SAM-P/10 presumably accounts for the age-related deficits in conditional avoidance learning in this strain of mouse. Comparison between SAM-P/10 and SAM-R/1 or other well-known rodents indicates that SAM-P/10 is a unique rodent that spontaneously and rapidly develops progressive generalized cerebral atrophy, which is considered to be a pathological process rather than an accelerated aging process.

Aging↗
PubMed1994

Effects of 2,5-dimethylpyrazine on plasma testosterone and polyamines- and acid phosphatase-levels in the rat prostate.

The effects of 2,5-dimethylpyrazine (DMP) on plasma testosterone and levels of polyamines and acid phosphatase in the prostate of rat were studied. A high dose of DMP administered once daily for two weeks to juvenile male rats significantly decreased plasma testosterone and levels of polyamines and acid phosphatase in the prostate. These effects were not obtained by administration to mature male rats, and the inhibition was thus recognized to occur during the growth period. These findings suggest that a high dose of DMP inhibits the biosynthesis of polyamines and acid phosphatase in the prostate by decreasing the circulating testosterone level.

Acid Phosphatase↗
PubMed1994

Isolation and characterization of two chitin synthase genes of Rhizopus oligosporus.

Two chitin synthase genes (chs1 and chs2) were isolated from Rhizopus oligosporus by plaque hybridization probed with the chitin synthase 2 gene of Saccharomyces cerevisiae. From their deduced amino acid sequences, they were both class II chitin synthases according to the classification proposed by Bowen et al. The expression of these genes was controlled differently in each stage of differentiation. It was suggested that the gene products of chs1 and chs2 function mainly in the hyphae growing stage but not in the late stage of spore formation. When each of these genes was expressed in S. cerevisiae, elevation of chitin synthase activity was observed in both cases.

Amino Acid Sequence↗
PubMed1994

Isolation and characterization of two chitin synthase genes from Aspergillus nidulans.

Two chitin synthase genes, designated chsA and chsB, were isolated from Aspergillus nidulans with the Saccharomyces cerevisiae CHS2 gene as the hybridization probe. Nucleotide sequencing showed that chsA and chsB encoded polypeptides consisting of 1013 and 916 amino acid residues, respectively; the hydropathy profiles of the enzymes were similar to those of other fungal chitin synthases. Northern analysis indicated that both genes were transcribed, suggesting that cellular chitin in A. nidulans is synthesized by at least two chitin synthases. For examination of the roles of the chitin synthase genes in cell growth, gene disruption experiments were done. The chsA disruptant grew as well as the wild-type strain, but the chsB disruptant had severe growth defects that could not be overcome by the addition of 1.2M sorbitol as an osmotic stabilizer. These findings suggested that chsB but not chsA is essential for hyphal growth.

Amino Acid Sequence↗
PubMed1994

Isolation of a chitin synthase gene (chsC) of Aspergillus nidulans.

We isolated a class I chitin synthase gene (chsC) from Aspergillus nidulans. Expression of this gene was confirmed by Northern analysis and by sequencing of the PCR-amplified DNA fragments from cDNA. chsC disruptants showed no difference of morphology in the asexual cycle and no difference of growth rate compared to a wild-type strain.

Amino Acid Sequence↗
PubMed1994

Inhibition of collagen production by traditional Chinese herbal medicine in scleroderma fibroblast cultures.

The in vitro effect of one traditional Chinese herbal medicine (Japanese name: "Keishi-bukuryo-gan"), which has been empirically used in scleroderma patients in China and Japan, on collagen production in fibroblast cultures was studied. Fibroblasts from 3 scleroderma patients and 2 normal controls were incubated with various concentrations of "Keishi-bukuryo-gan" and collagen production was then determined by a radiochemical method. "Keishi-bukuryo-gan" significantly and selectively inhibited collagen synthesis in a dose-dependent manner, with a tendency of a stronger effect on scleroderma fibroblasts than control cells. The results may explain the clinical usefulness of this medicine, and it may become a promising new agent for the treatment of scleroderma.

Adult↗
PubMed1994

Effects of fructooligosaccharides on the absorption of magnesium in the magnesium-deficient rat model.

Magnesium (Mg) is an essential dietary element that plays important roles, acting as a cofactor of many enzymes. Rats fed a Mg-deficient diet have been reported to exhibit auricular and facial peripheral hyperemia and hemorrhage. Moreover, increased intake of calcium (Ca) or phosphorus (P) has been reported to impair apparent absorption of Mg. We tried to induce such typical inflammation in Mg-deficient rats by feeding low-Mg, high-Ca, and high-P diets. Increasing concentrations of Ca or P in the experimental diets significantly decreased the apparent absorption of Mg. And all rats fed the low-Mg (0.25 mg/g diet), high-Ca (10.4 mg/g diet), and high-P (12.0 mg/g diet) diet exhibited auricular and facial peripheral-hyperemia and hemorrhage. Then, we used the low-Mg, high-Ca, and high-P diet to investigate the effects of the fructooligosaccharides (FO) on absorption of Mg and skin inflammation. In the rats fed FO-containing (1 or 5%) diet, apparent absorption of Mg was significantly increased as compared with that of the control (FO 0%) group. In the rats fed a 5% FO-containing diet and sufficient Mg (0.50 mg/g), auricular and facial peripheral hyperemia and hemorrhage were significantly reduced. We concluded that FO increased the Mg absorption in rats fed a low-Mg, high-Ca, and high-P diet. Moreover, FO reduced inflammation in Mg-deficient rats, such as peripheral hyperemia and hemorrhage.

Animals↗
PubMed1994

Effects of fructooligosaccharides on the absorption of magnesium and calcium by cecectomized rats.

We reported previously that feeding of fructooligosaccharides (FO) increased the apparent absorption of calcium (Ca), magnesium (Mg) and phosphorus (P) in rats. We suggested that there was an important correlation between this phenomenon and fermentation of FO in the large intestine. However, the precise mechanism remained to be characterized. Therefore, we performed a mineral-balance study to identify the segment of lumen in which FO affects mineral absorption, using cecectomized rats. Sham-operated rats and cecectomized rats were fed a control diet (without FO) or an FO-diet (containing 50 g of FO per kg of feed) for 28 days. Feeding of the FO-diet decreased the luminal pH in the cecum and colon in the sham-operated rats. In the cecectomized rats, feeding of the FO-diet also decreased the luminal pH in the colon. Thus, FO was fermented in the colon of the cecectomized rats. However, the acid composition of feces was altered by cecectomy. Feeding of the FO-diet increased the absorption of Ca and Mg in the sham-operated rats. In the cecectomized rats, the FO-diet increased the absorption of Mg but did not increase the absorption of Ca. These results suggest the mechanisms for the absorption of Ca and Mg when rats are fed an FO are different.

Animals↗