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Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 901 records · Page 50Linked to original sources
PubMed1987

Morphology of masticatory motoneurons stained intracellularly with horseradish peroxidase.

Masticatory motoneurons were identified electrophysiologically and stained with horseradish peroxidase (HRP). The masseter motoneurons could be divided into 3 groups on the basis of their dendritic morphology. In contrast, the digastric or mylohyoid motoneurons showed a similar dendritic configuration. These neurons had much developed dendritic trees in the dorsomedial than ventrolateral direction. The first group of the masseter motoneurons had their dendritic trees which extended radially in all directions with a slight preference to project rostrally. These somata were located in the center of the subdivision containing the masseter motoneurons. In the second group, their dendritic arbores had a polarity extending hemispherically. These neuronal somata were located in the medial, ventral, and lateral regions of the subdivision. For the masseter motoneurons in the two groups and jaw-opening motoneurons, the dendritic swellings were frequently observed in the distal branches. The third group had their dendritic trees which were much simpler in configurations with less tapering or branching than those of other neurons examined. Furthermore, a wide variety of dendritic spines and appendages, and no dendritic swellings, observed in the third group were distinct from other neurons stained. The dendritic trees of the jaw-closing and -opening motoneurons were confined to the individual subdivisions. There were no instances in which axon collaterals were observed for well-stained 16 axons.

Action Potentials↗
PubMed1987

A single nucleotide base transition is the basis of the common human glucose-6-phosphate dehydrogenase variant A (+).

The X-chromosome-linked glucose-6-phosphate dehydrogenase (G6PD) A(+) is a common variant found in about 20% of blacks. The amino acid substitution of Asp in the variant G6PD A(+) for Asn in the normal G6PD B(+) was previously found (A. Yoshida, 1967, Proc. Natl. Acad. Sci. USA 57: 835), but the exact substitution position has not been identified. By screening a DNA library prepared from genomic DNA of a G6PD A(+) male subject, we obtained a genomic clone that contained the mutation site. Characterization of the clone revealed that AT----GC transition occurred in the variant A(+) gene, thus producing the amino acid substitution Asn----Asp at the 142nd position from the NH2 terminus of the enzyme. The nucleotide change created an additional FokI cleavage site in the variant A(+) gene; thus, the FokI fragment type of the variant subjects differed from that of normal B(+) subjects in Southern blot hybridization analysis.

Amino Acid Sequence↗
PubMed1987

Cytogenetic and molecular studies on a recombinant human X chromosome: implications for the spreading of X chromosome inactivation.

A pericentric inversion of a human X chromosome and a recombinant X chromosome [rec(X)] derived from crossing-over within the inversion was identified in a family. The rec(X) had a duplication of the segment Xq26.3----Xqter and a deletion of Xp22.3----Xpter and was interpreted to be Xqter----Xq26.3::Xp22.3----Xqter. To characterize the rec(X) chromosome, dosage blots were done on genomic DNA from carriers of this rearranged X chromosome using a number of X chromosome probes. Results showed that anonymous sequences from the distal end of the long arm to which probes 4D8, Hx120A, DX13, and St14 bind as well as the locus for glucose-6-phosphate dehydrogenase (G6PD) were duplicated on the rec(X). Mouse-human cell hybrids were constructed that retained the rec(X) in the active or inactive state. Analyses of these hybrid clones for markers from the distal short arm of the X chromosome showed that the rec(X) retained the loci for steroid sulfatase (STS) and the cell surface antigen 12E7 (MIC2); but not the pseudoautosomal sequence 113D. These molecular studies confirm that the rec(X) is a duplication-deficiency chromosome as expected. In the inactive state in cell hybrids, STS and MIC2 (which usually escape X chromosome inactivation) were expressed from the rec(X), whereas G6PD was not. Therefore, in the rec(X) X chromosome inactivation has spread through STS and MIC2 leaving these loci unaffected and has inactivated G6PD in the absence of an inactivation center in the q26.3----qter region of the human X chromosome. The mechanism of spreading of inactivation appears to operate in a sequence-specific fashion. Alternatively, STS and MIC2 may have undergone inactivation initially but could not be maintained in an inactive state.

Abnormalities, Multiple↗
PubMed1987

Effect of amino acid supplementation to low protein diet on brain and plasma levels of tryptophan and brain 5-hydroxyindoles in rats.

The contribution of amino acid transport across the blood-brain barrier toward the concentration of brain 5-hydroxyindoles [serotonin and 5-hydroxyindole acetic acid (5HIAA)] was investigated. Several amino acids were individually supplemented to a 5% whole egg protein diet. Close correlation between serum tryptophan, brain tryptophan and 5-hydroxyindoles were observed regardless of diet fed. When a large neutral amino acid (LNAA such as methionine, threonine, leucine or phenylalanine) was added to the control diet, brain 5-hydroxyindole concentration was lower than when the control diet was fed; however, when tryptophan was added, brain 5-hydroxyindole concentration was significantly higher. Lysine supplementation did not affect brain 5-hydroxyindole concentration. Leucine supplementation caused a lower tyrosine concentration in hypothalamus than the control diet, but phenylalanine supplementation caused higher hypothalamus level of tyrosine. There was no correlation between tyrosine and norepinephrine concentrations in hypothalamus (norepinephrine turnover might also be changed by the nutritional state). These observations indicate that the supplementation of an amino acid at two- or fourfold of the requirement to a low protein diet can generate major changes in the concentrations of neurotransmitters in rats.

Amino Acids↗
PubMed1987

Effect of dietary ascorbic acid, cholesterol and PCB on cholesterol concentrations in serum and liver in a rat mutant unable to synthesize ascorbic acid.

The effect of ascorbic acid deficiency and excessive ascorbic acid intake on serum and liver levels of cholesterol and lipids was investigated in ODS-od/od (OD) rats fed a normal diet, a cholesterol-containing diet or a polychlorinated biphenyl (PCB)-containing diet. The OD rat is a rat mutant unable to synthesize ascorbic acid. In OD rats, the dietary requirement of ascorbic acid to maintain normal growth and normal levels of cholesterol in serum and liver is about 300 mg of ascorbic acid/kg diet. In control (ODS-+/+) rats that can synthesize ascorbic acid, dietary addition of 0.5% cholesterol and 0.25% cholic acid caused elevation of cholesterol concentrations in serum and liver, elevation of total lipids in liver and reduction of the ratio of high density lipoprotein (HDL) cholesterol to total cholesterol in serum. Dietary addition of PCB (200 mg/kg diet) caused elevation of serum concentration of cholesterol and of the ratio of HDL-cholesterol to total cholesterol in serum. In OD rats fed a normal diet, ascorbic acid deficiency slightly elevated serum concentration of cholesterol, elevated liver concentration of cholesterol and reduced the ratio of HDL-cholesterol to total cholesterol in serum; and ascorbic acid excess did not affect serum and liver concentrations of cholesterol and the ratio of HDL-cholesterol to total cholesterol in serum. In OD rats fed a cholesterol-containing diet, ascorbic acid deficiency elevated serum and liver concentrations of cholesterol, and did not affect the ratio of HDL-cholesterol to total cholesterol in serum; and ascorbic acid excess did not affect serum and liver concentrations of cholesterol and the ratio of HDL-cholesterol to total cholesterol in serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Long-term effects of dietary polychlorinated biphenyl and high level of vitamin E on ascorbic acid and lipid metabolism in rats.

Long-term feeding of purified diets containing (per kg diet) 100 mg of polychlorinated biphenyl (PCB) and 1000 mg of vitamin E (RRR-alpha-tocopheryl acetate) to male Wistar rats was carried out. Rats fed a diet containing PCB rapidly became hypercholesterolemic and maintained high cholesterol levels throughout the 240 d of the experiment. Rats fed a high dietary level of vitamin E plus PCB had higher serum cholesterol and lower liver cholesterol than rats fed a lower level of vitamin E plus PCB. In rats fed PCB, urinary excretion of ascorbic acid was higher than in rats not fed PCB. Urinary ascorbic acid was lower in rats fed high levels of vitamin E plus PCB than in those fed the normal levels of vitamin E plus PCB. Rats fed PCB had lower liver vitamin A storage and higher vitamin A in kidney than rats not fed PCB. This implies that a redistribution of vitamin A occurred in rats fed PCB. Histological observations revealed that central halves of the hepatic lobules of rats fed PCB showed distinct changes consisting of hypertrophy of hepatocytes in the perivenous region and accumulation of vacuoles (lipid droplets) in the cells in the remaining affected portion. Administration of a high dose of vitamin E could not ameliorate this lesion while the treatment depressed effectively the lipid peroxidation. This suggests that the lipid peroxidation was not responsible for the hepatic damage induced by PCB.

Animals↗
PubMed1987

Beta-adrenergic regulation of contractility and protein phosphorylation in spontaneously beating isolated rat myocardial cells.

Spontaneously beating heart myocytes were prepared from adult rat ventricular tissues to study the correlation between beta-adrenergic receptor-stimulated changes in contractile performance and protein phosphorylation in vitro. The plasma membrane of isolated myocardial cells was permeabilized by saponin in the presence of EGTA and Mg-ATP. The permeabilized myocytes, which formed a homogeneous cell population, retained the rod-cell morphology of heart cells in situ and showed spontaneous cyclic contractions. Their contractile activity in response to extracellularly added cAMP mimicked the effects caused by beta-adrenergic stimulation of the whole heart: both the frequency and longitudinal velocity of free contraction and relaxation of the cells increased. Similar increases were observed when beta-agonist, isoproterenol, and GTP were added to suspending medium. In addition, isoproterenol maximally enhanced the adenylate cyclase activity of the cells in the presence of GTP. Both of these effects of isoproterenol were completely blocked by the beta-antagonist propranolol. cAMP-mediated phosphorylation of proteins in the permeabilized myocytes was investigated under conditions in which the beating frequency increased. cAMP elevated the phosphorylation level of five proteins; three of them with apparent molecular masses of 24, 15, and 12 kDa were membrane proteins and the other two with apparent molecular masses of 150 and 28 kDa were myofibrillar proteins. The 24-kDa phosphoprotein dissociated into 12-kDa molecules when boiled in sodium dodecyl sulfate, suggesting that these proteins are oligomeric and monomeric forms of phospholamban. The phosphorylation of these five proteins was stimulated by isoproterenol. The effect of isoproterenol was enhanced by GTP but completely blocked by propranolol. The time course of their phosphorylation correlated well with that of the increase in the beating frequency of the cells; both were measured after the administration of isoproterenol and GTP. When propranolol was added after the start of the stimulation by isoproterenol, only phospholamban and the 15-kDa protein were rapidly dephosphorylated in close correlation with the decrease of the beating frequency. These results demonstrate for the first time that the permeabilized myocytes retain the functional beta-adrenergic receptor and cellular responses to beta-adrenergic stimulation. They also suggest that cAMP-mediated phosphorylation of proteins, possibly phospholamban and/or the 15-kDa protein, is involved in the increased contractile activity of permeabilized heart cells.

Adenosine Triphosphate↗
PubMed1987

Tissue-dependent expression of two (alpha 1----2)-fucosyltransferases specified by the H and Se genes.

Human blood group H substance is produced from its percursor by the action of (alpha 1----2)-fucosyltransferase. In a classical model, the Se gene that determines secretor status is a regulatory gene controlling the expression of H gene-specified fucosyltransferase in the secretory tissues. However, recent biochemical evidence supports a new genetic model in which the H and Se genes are both structural genes encoding two fucosyltransferases with different characteristics. The H gene-specified enzyme (H enzyme) is absent in secretory tissues and secretory fluids, while the Se gene-specified enzyme (Se enzyme) is missing in hematopoietic tissues. The H enzyme has a much lower Km for phenyl-beta-galactoside than does the Se enzyme. The tissue-dependent expression of the two enzymes was examined according to this criteria. The H enzyme was found to be predominant in the tissues of secretors examined (lung, liver, kidney, stomach, and skeletal muscle). While the Se enzyme exists in the secretor's lung, liver and kidney, very little or none is found in the stomach and skeletal muscle tissues.

ABO Blood-Group System↗
PubMed1987

Lower serum free thyroxine (T4) levels in painless thyroiditis compared with Graves' disease despite similar serum total T4 levels.

Serum total T4 (T4), total T3 (T3), free T4 (FT4), free T3 (FT3), and T4-binding globulin concentrations and T3 resin uptake values were measured in 17 women with thyrotoxicosis due to painless thyroiditis (PT) and compared with the same parameters in 17 women with thyrotoxicosis due to Graves' disease (GD) with similar serum T4 levels. The mean serum T3 resin uptake value and T3, FT4, and FT3 concentrations in the PT patients were significantly lower than those in the GD patients. The mean serum T4-binding globulin concentration [20.2 +/- 4.2 (+/- SD) microgram/mL] in patients with PT did not differ significantly from those in patients with GD (18.0 +/- 2.6 micrograms/mL) and normal euthyroid women (21.9 +/- 4.0 micrograms/mL). The serum T3 to T4 (nanogram per microgram) ratio was higher than 20 in 14 GD patients, but lower than 20 in all patients with PT, whereas the individual serum FT3 to FT4 ratio values considerably overlapped in the 2 groups. In patients with PT, FT4 correlated well with T4 at various times during the clinical course. These findings indicate that the elevation in serum FT4 in patients with PT is mostly due to the increase in circulating T4 levels, whereas GD patients also have some diminution in T4 binding. The serum T3 to T4 ratio, but not the FT3 to FT4 ratio, may be helpful for differentiation between the two diseases.

Adolescent↗
PubMed1987

Examination of exchange assay for glucocorticoid receptor.

We examined a method for the measurement of total, activated and non-activated glucocorticoid receptors using sodium-p-hydroxymercuribenzoate (PHMB) and dithiothereitol (DTT) developed by Banerji and Kalimi (1981). Since the concentration of PHMB required for dissociation of the ligand from the receptors varied with the concentration of protein in the reaction mixture and the rate of reassociation of the ligand to the ligand-liberated receptors was sensitive to the concentration of PHMB used, it was necessary to find the minimum concentration of PHMB which was required for complete dissociation of the ligand. When the optimum concentration of PHMB was selected based on the concentration of protein in the cytosol, almost 100% exchange was attained in the non-heated dexamethasone (Dex)-receptor complexes by this method. However when Dex-receptor complexes were heated at 25 degrees C for 30 min, the amount of 3H-Dex reassociated with the glucocorticoid receptors dropped to 60% of that of the non-heated ones. DEAE-cellulose chromatography of the heated sample revealed that approx. 40% of the bound receptors were activated (eluted with 0.05 M KCl) during the heating period. After DEAE cellulose column chromatography of the exchanged 3H-Dex receptor, complexes reassociated with 3H-Dex were observed only in the fraction of unactivated receptor complexes (eluted with 0.2 M KCl). Furthermore, the fraction eluted with 0.05 M KCl in the DEAE cellulose chromatography of liver cytosol bound to unlabelled Dex did not exchange significantly with 3H-Dex with the method used in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Serum free thyroxine and thyroxine-binding globulin concentrations in early phase of subacute thyroiditis.

Serum total thyroxine (T4), total triiodothyronine (T3), T4-binding globulin (TBG), free T4(FT4) and free T3(FT3) concentrations and the T3-uptake(T3-U) value were estimated in 11 patients with subacute thyroiditis, and compared with the same parameters in 11 patients with Graves' disease, whose serum T4 concentrations were similar to the former group. Seven patients with subacute thyroiditis, who were treated with dicrofenac sodium alone, were investigated as to the sequential changes in serum parameters during their clinical courses. The mean serum T3-U value and FT4, T3 and FT3 concentrations in patients with subacute thyroiditis were increased, but all were significantly lower than those in patients with Graves' disease (p less than 0.01, p less than 0.001, p less than 0.001 and p less than 0.001, respectively). Three patients with subacute thyroiditis, who showed shorter duration of symptoms than 10 days, had serum TBG excess. Thus the mean (+/- SD) serum TBG concentration (26.5 +/- 8.4 micrograms/ml) was significantly higher than that (18.3 +/- 2.9 micrograms/ml) in patients with Graves' disease (p less than 0.02). The ratios of serum T3 to T4 and FT3 to FT4 in patients with subacute thyroiditis were also significantly lower than those in patients with Graves' disease (p less than 0.001 and p less than 0.001, respectively). The serum FT4 in 7 patients treated with dicrofenac sodium alone decreased to the normal range after 3 to 8 weeks from the onset of the illness. In 3 patients with TBG excess and one patient (TBG; 29.0 micrograms/ml), serum TBG declined in consequence of the serum FT4 normalization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Spontaneous tumors in F344/DuCrj rats from 12 control groups of chronic and oncogenicity studies.

The types and incidences of spontaneous tumors in F344/DuCrj rats were examined in 960 males and 959 females served as the control groups of separate twelve 2-year chronic and oncogenicity studies carried out during a 1978-1983 period. The major tumors occurred at more than 5% incidence were leukemia (mononuclear cell), testicular interstitial cell tumor, preputial gland adenoma, pituitary anterior adenoma, thyroid C-cell adenoma, adrenal pheochromocytoma and subcutis fibroma for males, and leukemia, uterine endometrial polyp, pituitary anterior adenoma, thyroid C-cell adenoma and mammary gland adenoma/fibroadenoma in females. Analyses on age-related occurrence of tumors revealed that the incidences of most of the major tumors in males attained already to the plateau between 85 and 97 weeks of age while those in females showed a steep rise during the last interval of observation, 98 to 110 weeks of age. An intralaboratory heterogeneity in incidence was observed in the thyroid C-cell adenoma and the adrenal pheochromocytoma for males, and the anterior pituitary adenoma for females.

Adrenal Gland Neoplasms↗
PubMed1987

Toxicity of D, L-mandelonitrile-beta-D-glucoside, "prulaurasin" in rat.

Toxicity of cyanogenetic glucoside was studied with rats using synthesized D, L-mandelonitrile-beta-D-glucoside. Considering from blood cyanide level, the cause of death was presumed to be cyanide intoxication. Hydrolysis of cyanogenetic glucoside occurred mainly in small and large intestines. Cyanide level in the intestine seemed to be independent of the amount of glucoside present. LD50 value was calculated to 560 mg/kg but good dose dependent result was not obtained. Relatively rapid absorption of the glucoside from the gastrointestinal tract was observed with the highest absorption rate of 53.4% within 165 min. About 30-45% of the administered glucoside was excreted within 24 hr without alteration and dose dependence appeared in an excreted ratio. The ratio of D-mandelonitrile-beta-D-glucoside to L-form excreted in the urine or remained in the gastrointestinal tract was almost in the same as at administration, and hence biological behaviors, such as absorption, excretion and hydrolysis, of both D- and L-forms of glucoside were almost the same.

Animals↗
PubMed1987

Short-term prednisolone for inducing seroconversion from hepatitis B e antigen to antibody along with clinical improvement in patients with chronic active hepatitis type B.

Short-term prednisolone therapy was instituted on 27 patients with chronic active hepatitis (CAH) type B, in an attempt to induce seroconversion from hepatitis B e antigen (HBeAg) to the corresponding antibody (anti-HBe). Patients with CAH received a four-week regimen of prednisolone with daily dosage tapering from 40 to 10 mg (total 700 mg). Within one year after the withdrawal of prednisolone, 19 (70%) lost HBeAg and 11 of them (41% of the total) developed anti-HBe, at rates significantly higher than 3 (12%) and 1 (4%) who spontaneously showed respective serological changes among 26 matched controls during one year (p less than 0.001). Within two years after the withdrawal, 21 (78%) lost HBeAg and 19 (70%) developed anti-HBe, in contrast to 6 (23%) and 2 (8%) of controls who showed respective changes during that period (p less than 0.001). Seroconversion to anti-HBe was invariably accompanied by clinical and biochemical improvements along with loss of DNA polymerase from circulation. Elevation in transaminase levels, reflecting the rebound of steroid withdrawal, always heralded and appeared to be required for the seroconversion, but serious aggravation of hepatitis was not encountered in any of the patients.

Adult↗