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Biomedical subjects

F Yoshimura

Publications and source records attributed to F Yoshimura.

At least 55 records · Page 3Linked to original sources
PubMed1985

Diffusion of beta-lactam antibiotics through the porin channels of Escherichia coli K-12.

Diffusion rates of various beta-lactam antibiotics through the OmpF and OmpC porin channels of Escherichia coli K-12 were measured by the use of reconstituted proteoliposomes. The results can be interpreted on the basis of the gross physicochemical properties of the antibiotics along the following lines. (i) As noted previously (Nikaido et al., J. Bacteriol., 153:232-240, 1983), there was a monotonous dependence of the penetration rate on the hydrophobicity of the molecule among the classical monoanionic beta-lactams, and a 10-fold increase in the octanol-water partition coefficient of the uncharged molecule decreased the penetration rate by a factor of 5 to 6. (ii) Compounds with exceptionally bulky side chains, such as mezlocillin, piperacillin, and cefoperazone, showed much slower penetration rates than expected from their hydrophobicity. (iii) The substituted oxime side chain on the alpha-carbon of the substituent group at position 7 of the cephem nucleus decreased the penetration rate almost by an order of magnitude; this appears to be largely due to the steric effect. (iv) The presence of a methoxy group at position 7 of the cephalosporins also reduced the penetration rate by 20%, probably also due to the steric hindrance. (v) Zwitterionic compounds penetrated very rapidly, and the correlation between the rate and hydrophobicity appeared to be much weaker than with the monoanionic compounds. Imipenem showed the highest permeability among the compounds tested, presumably due, at least in part, to its compact molecular structure. (vi) Compounds with two negative charges penetrated more slowly than did analogs with only one negatively charged group. Among them, only moxalactam, ceftriaxone, and azthreonam showed penetration rates corresponding to, or higher than, 10% of that of imipenem.

Anti-Bacterial Agents↗
PubMed1985

Fimbriae from the oral anaerobe Bacteroides gingivalis: physical, chemical, and immunological properties.

Circular dichroism spectra indicated the predominance of beta-sheet structure in Bacteroides gingivalis fimbriae regardless of the presence of sodium dodecyl sulfate. By using a computer program, the alpha-helix, beta-sheet, and beta-turn contents and the remainder were estimated to be 0, 55, 18, and 27%, respectively, judging from the circular dichroism spectra of the fimbriae. Heating for 5 min at 100 degrees C in sodium dodecyl sulfate was necessary to denature the fimbriae into their constituent protein (fimbrilin) monomers with a reduced content of beta-sheet structure. The amino-terminal amino acid sequence of the fimbrilin was different from partial or complete amino acid sequences of fimbrilins so far determined from Bacteroides nodosus, which falls into the same nonfermentative species of the genus Bacteroides as B. gingivalis, and from various other bacteria. Fimbrilin monomers had an isoelectric point of 6.0. Examination of antibodies against fimbriae and sodium dodecyl sulfate-denatured fimbrilin by enzyme-linked immunosorbent assay reinforced a previous notion (F. Yoshimura, K. Takahashi, Y. Nodasaka, and T. Suzuki, J. Bacteriol. 160:949-957, 1984) that different sets of antigenic determinants seemed to be exposed on their surfaces.

Amino Acid Sequence↗
PubMed1985

Relationship between characteristics of immunoreactive LH/FSH cells and the levels of gonadotropin in the female rat.

Morphological and functional changes of pituitary LH/FSH cells in the female rat were investigated using the parameters on the radioimmunoassay, immunohistochemistry and ultrastructure. Changes in immunostainability, populations of intensely immunostained LH and FSH cells and total volume of secretory granules were correlated with the changes in pituitary LH and FSH contents during the estrous cycle. The immunohistochemical feature of gonadotropin release is the transformation of intensely immunostained gonadotrophs into the weakly stained ones. Secretory granules of small diameter (less than 150 nm) were numerous just before LH and FSH surges then sharply declined along with LH and FSH surges. The number of secretory granules of large diameter (larger than 150 nm) also decreased when LH and FSH surges took place. Then the number increased progressively until 17.00 h on the day of diestrus, corresponding to the increase in pituitary LH and FSH contents. It is suggested that small secretory granules are a release pool while large ones are a reserve pool.

Animals↗
PubMed1985

Estrogen induced prolactin mRNA accumulation in adult male rat pituitary as revealed by in situ hybridization.

Adult male rats were injected with different doses (1, 10, and 100 micrograms) of 17 beta-estradiol daily for 5 days, and the changes in prolactin (PRL) mRNA levels were examined by in situ hybridization and cytoplasmic dot blot hybridization using cloned cDNA for rat prolactin mRNA. An increase in cytoplasmic PRL mRNA content was evident in all the animals treated with estrogen as revealed with cytoplasmic dot blot analysis. There were however, no significant differences in PRL mRNA content among the three estradiol treated groups. Cytoplasmic PRL mRNA was also demonstrated by in situ hybridization on the frozen pituitary sections using a 3H-labeled PRL cDNA probe. The number of grains per cell was increased after estrogen treatment. 3H-thymidine uptake into pituitary cells was also examined in vivo using combined techniques of immunocytochemistry and autoradiography. Although the percentage of immunoreactive PRL cells which took up thymidine in their nuclei increased to more than double after estrogen treatment, the increase in the total number of immunoreactive PRL cells was small. These results suggest that the major effect of estrogen on PRL cells is an increase in the accumulation of PRL mRNA in the individual PRL cells. The number of grains per cell was found to vary from cell to cell, both in control and estrogen treated animals. This variability is discussed in relation to the functional heterogeneity within the PRL cell population.

Animals↗
PubMed1984

Granulated folliculo-stellate cells and growth hormone cells immunostained with anti-S 100 protein serum in the pituitary glands of the goat.

Goat pituitary glands were immunohistochemically studied with antisera for bovine S-100 protein, rat LH beta, FSH, TSH beta, prolactin, ovine GH, and porcine ACTH1-39 by use of the superimposition technique on adjacent sections. Folliculo-stellate (F-S) cells were divided into two categories on the basis of ultrastructural properties: One consisted of a mass of agranular cells in which the pseudolumina were equipped with microvilli and cilia. Elongate gap junctions were often observed among these cells. The other was a group of granulated cells with or without pseudolumina. In this group the gap junctions were shown to be disintegrated. The dense granules 150-250 nm in diameter began to accumulate in the cells. However, neither type of these F-S cells was immunostained for S-100 protein. On the other hand, numerous polygonal, elongate, irregular or stellate cells containing S-100 protein were distributed throughout the gland. Most of them were immunohistochemically identical with the GH cells laden with the secretory granules 250-450 nm in diameter, but some of them were identical to TSH and prolactin cells which immunostained faintly for S-100 protein. This appears to be the first demonstration of GH cells intensely immunostained for S-100 protein.

Animals↗
PubMed1984

Characterization of a trypsin-like protease from the bacterium Bacteroides gingivalis isolated from human dental plaque.

A trypsin-like, membrane-bound protease from Bacteroides gingivalis was solubilized by Triton X-100 and partially purified by a combination of DEAE-Sepharose and aminophenylmercuric Sepharose chromatography, by taking advantage of the thiol group on the enzyme. The purified enzyme hydrolysed the synthetic substrates benzoyl-L-arginine-p-nitroanilide (L-BAPA), benzoyl-D,L-arginine-beta-naphthylamide (BANA) and tosyl-L-arginine methyl ester, as well as bovine serum albumin and ovalbumin, but not tosyl-L-lysine methyl ester. The enzyme activity was enhanced by SH-reagents and was inhibited to different degrees by SH-inhibitors, chelators and microbial low-molecular-weight inhibitors such as leupeptin, antipain and chymostatin. These microbial inhibitors could be of practical use as ligands for affinity chromatography for further purification. The possible involvement of the protease in periodontal diseases is also discussed.

Bacteroides↗
PubMed1984

Purification and characterization of a novel type of fimbriae from the oral anaerobe Bacteroides gingivalis.

Fimbriae and their constituent protein (fimbrilin) were purified to homogeneity from the bacterial wash fluid and cell lysate fraction, respectively, of Bacteroides gingivalis 381. Fimbriae, observed by negative staining, were curly, single-stranded filaments with a diameter of ca. 5 nm. The apparent molecular weight of the fimbrilin was 43,000. Fimbriae were resistant to sodium dodecyl sulfate denaturation at 70 degrees C. Heating at 100 degrees C in sodium dodecyl sulfate was needed to completely dissociate them to monomers of fimbrilin. Different sets of antigenic determinants seemed to be exposed on the surfaces of fimbriae and sodium dodecyl sulfate-denatured fimbrilin. Purified fimbriae did not show either hemagglutinating activity or hemagglutination inhibitory activity, although it has been inferred on the basis of circumstantial evidence that fimbriae are correlated to hemagglutinating activity of the organism. Hemagglutinin activity, however, was detected in culture supernatant, and this observation suggests that fimbriae of a different type or a lectin-like protein may be acting as hemagglutinin in B. gingivalis.

Amino Acids↗
PubMed1984

A histometrical study of immunohistochemically identified mitotic adenohypophysial cells in immature and mature castrated rats.

Two weeks after operation the effects of castration on all types of mitotic adenohypophysial cells in 30-day-old (immature) and 75-day-old (mature) male rats were studied immunohistochemically by light microscopy. The total number of mitotic cells in gland specimens increased 1.4 times in immature rats, but remained unchanged in mature animals; mitotic activity (mitotic cell number/mm2) was not affected in either age group. The population of mitotic gonadotrophs increased five to six times in comparison with intact controls. In addition, the percentage of mitotic gonadotrophs and their mitotic activity were raised in both age groups. Castration affected the mitosis of prolactin cells. The percentage of mitotic prolactin cells was reduced by one-third in castrated immature rats, but the total number and percentage of mitotic prolactin cells, as well as their mitotic activity, was reduced by about two-thirds in mature castrated rats. No significant changes in mitotic ACTH, TSH, GH and immunonegative cells were found after castration in either group of animals. Mitotic cells were more numerous in the anterior than in the posterior region of the gland in normal (uncastrated) immature rats, but were uniformly scattered in both regions in normal mature rats. On the other hand, castration induced a high population of mitotic cells in the anterior region regardless of age. This high population was the result of the enhanced mitosis of gonadotrophs. It is concluded that 2 weeks after castration the increment of mitotic divisions of all types of pituitary cells is age-dependent, and that mitosis takes place frequently in gonadotrophs and less frequently in prolactin cells.

Adrenocorticotropic Hormone↗
PubMed1984

Evaluation of plasma histamine in patients with coronary artery disease.

Plasma levels of histamine (HI) were determined by fluorescence photometry in 12 patients with old myocardial infarction, 10 patients with stable effort angina pectoris and 10 control subjects without coronary arterial lesion. Resting HI were 57.6 +/- 7.5 ng/ml for control subjects and 68.6 +/- 3.9 ng/ml for patients with coronary artery disease (CAD) (N.S.). HI were 62.6 +/- 4.7 ng/ml for patients with one vessel disease, 68.0 +/- 10.6 ng/ml for patients with two vessel disease and 79.1 +/- 4.9 ng/ml for patients with three vessel disease (one vessel disease: three vessel disease, p less than 0.05). HI for all subjects decreased from 65.6 +/- 3.5 ng/ml before treadmill exercise test to 63.4 +/- 3.8 ng/ml after exercise (N.S.), and the rate of change did not differ from control subjects to diseased patients. HI increased significantly from 63.5 +/- 3.7 ng/ml to 70.7 +/- 3.7 ng/ml after hyperventilation (p less than 0.05), but the rate of change did not differ from control to CAD patients. In the present study a tendency was observed that the severe the coronary arterial lesions, the higher were HI. In old myocardial infarction and stable effort angina pectoris, however, the changes in HI produced by exercise and hyperventilation do not seem to be deeply involved in the onset of acute myocardial ischemia.

Coronary Disease↗
PubMed1983

Pituitary folliculo-stellate cells immunostained with S-100 protein antiserum in postnatal, castrated and thyroidectomized rats.

Pituitary folliculo-stellate cells and associated cells were studied immunohistochemically throughout the life of male and female rats. The marginal layer cells of the pars distalis and intermedia as well as the folliculo-stellate cells were immunostained with anti-S 100 protein serum. The immunostained folliculo-stellate cells in one section were identified as themselves by their ultrastructural properties on the adjacent section. Corticotrophs, thyrotrophs and prolactin cells, characterized by the stellate shape, were not immunostained with anti-S 100 protein serum. Reactivity for S-100 protein appeared on postnatal Day 6 in the marginal layer cells of the pars intermedia, and appeared on Day 10 in those cells of the pars distalis. No immunostained folliculo-stellate cells appeared before Day 6, but a few of them appeared on Day 10. Thereafter they increased in number, having more intense immunostaining with advancing age. In castrated rats, the immunostained folliculo-stellate cells appeared quite numerously, with branched cytoplasmic processes surrounding the gonadotrophs. In the thyroidectomized rats, however, folliculo-stellate cells lacked ramified cytoplasmic processes, and their topographic affinity for thyrotrophs was negligible.

Age Factors↗
PubMed1982

Fine structural criteria of prolactin cells identified immunohistochemically in the male rat.

Immunoreactive prolactin (PRL) cells in the adult male rat pituitary were observed by light microscopy to be scattered throughout the gland without special localization but sometimes to form small clusters consisting of five to ten cells. The cells had oval, polygonal, and cuplike shapes. Using the "superimposition technique," the fine structural properties of the PRL cells were examined on ultrathin sections just adjacent to the thick plastic section for immunostaining. Four cell types were distinguished: (1) oval, polygonal, and elongate cells with only small spherical granules, 130-200 nm in diameter; (2) oval or polygonal cells with both medium-sized spherical granules (250-300 nm) and about same size of polymorphic granules; (3) polygonal cells containing only large polymorphic granules (300-700 nm in maximal diameter); (4) cup-shaped PRL cells with spherical and small polymorphic granules. Furthermore, the prolactin immunoreactivity of these cell types was confirmed by the electron immunohistochemistry. Type 1 cells resemble, in fine structure, Kurosumi-Oota LH-gonadotrophs, but the former are not stained with anti-rat LH beta serum, but with anit-rat PRL serum. Although the functional relationship between these four types of cells is still unclear, it is concluded that the polymorphic shape of the granules is not necessarily an absolute criterion for identification of the PRL cell in the male.

Animals↗
PubMed1982

Fine structural criteria for pituitary thyrotrophs in immature and mature rats.

Fine structural criteria for identifying thyroid-stimulating hormone (TSH) cells in immature and mature rats have been studied by a modified superimposition technique. On days 10 and 20, some small oval immature TSH cells are scattered individually throughout the glandular tissue with a peripheral immunoreactive rim resulting from the sparse distribution of minute secretory granules less than 50 nm in diameter. The immunostained stellate TSH cells are clustered and have secretory granules 50-100 nm in diameter at the cell margins. On day 60, a few small immature TSH cells still remain. Although a few polygonal TSH cells that may not fully mature accumulate secretory granules 100-150 nm in diameter at the cell margins, the majority of TSH cells take the form of large stellate cells filled with secretory granules with the corresponding diameter, and surround an acidophil. These stellate TSH cells are characterized by dense arrangement of parallel arrays of rough endoplasmic reticulum (rER) or rER cisternae. The clustered or isolated elongate TSH cells are also observed to be vesiculated and to have numerous secretory granules 150-250 nm in diameter. In addition, large oval vesiculated TSH cells storing numerous secretory granules 150-250 nm in diameter appear sporadically in the gland, ultrastructurally resembling the gonadotrophs. It is concluded that the rat TSH cell is not a single type with a particular ultrastructure, but modifies its morphology according to its maturation or functional phase.

Aging↗
PubMed1982

Immunohistochemical and electron microscopical studies of mitotic adenohypophysial cells in different ages of rats.

Mitotic rates of the six types of immunohistochemically identifiable adenohypophysial cells were histometrically calculated in colchicine-pretreated male rats 5, 17, 30 and 70 days old. Sections were stained with the antisera against rLH, rFSH, rTSH, oGH, rPRL and pACTH1-39. The mitotic growth rate of the anterior pituitary gland at 30 days of age was much higher than at other times. Mitotic growth rates of GH and PRL cells increased with advancing age, while those of ACTH-TSH- and immunonegative cells decreased with advancing age. LH/FSH cells showed no variation in mitotic growth rate with age. Mitotic cells can be classified into six cell types based on their fine structural properties: (1) agranular cells associated with the folliculo-stellate cells; (2) ambiguous cells with scanty minute secretory granules (50-150 nm in diameter); (3) basophils with a number of small secretory granules (130-200 nm); (4) immature acidophils whose large secretory granules (130-300 nm) are sporadically scattered; (5) acidophils with numerous spherical larger secretory granules (200-300 nm); and (6) prolactin cells with large polymorphic granules. At day 5 there was a high mitotic rate of the agranular and ambiguous cells [types (1) and (2)]; at day 70 a high mitotic rate was found in immature and mature acidophils [types (4) and (5)]. The mitotic rate of basophils (type 3) was high only at day 17 and low at all other times. The mitotic rate of prolactin cells (type 6) showed a slight increment with advancing age. It is concluded that the mitotic rates of the six cell types are age-dependent.

Aging↗
PubMed1982

Permeability of Pseudomonas aeruginosa outer membrane to hydrophilic solutes.

Pseudomonas aeruginosa is usually resistant to a wide variety of antibacterial agents, and it has been inferred, on the basis of indirect evidence, that this was due to the low permeability of its outer membrane. We determined the permeability of P. aeruginosa outer membrane directly, by measuring the rates of hydrolysis of cephacetrile, cephaloridine, and various phosphate esters by hydrolytic enzymes located in the periplasm. The permeability to these compounds was about 100-fold lower than in the outer membrane of Escherichia coli K-12. Also, we found that the apparent Km values for active transport of various carbon and energy source compounds were typically higher than 20 microM in P. aeruginosa, in contrast to E. coli in which the values are usually lower than 5 microM. These results also are consistent with the notion that the P. aeruginosa outer membrane indeed has a low permeability to most hydrophilic compounds and that this membrane acts as a rate limiting step in active transport processes with high Vmax values.

Cell Membrane Permeability↗