PubMed Health⌕ Search

Biomedical subjects

F Yoshimura

Publications and source records attributed to F Yoshimura.

At least 37 records · Page 2Linked to original sources
PubMed1986

Morphological characterization of LH secretory granule response to LHRH and calmodulin inhibitor.

A quantitative electron microscopy study was carried out to characterize the luteinizing hormone (LH) contained secretory granules in response to exogenous luteinizing hormone releasing hormone (LHRH) alone or in combination with calmodulin inhibitor (W13) in orchidectomized rats pretreated with estrogen. The plasma LH concentration rose quickly 30 min after a single large LHRH injection, and then gradually increased further until 150 min. However, the rise was attenuated by supplemental administration of W13 30 min after LHRH exposure. The mean diameter of secretory granules quickly decreased inversely to the increase of plasma LH concentration after LHRH injection. However, the mean diameter increased significantly in accordance with the complete attenuation of the increase in LH release caused by administration of W13. There was an inverse correlation between the diameter of secretory granules and plasma LH concentration. Small secretory granules with low electron density frequently appeared in castration cells after LHRH injection. It is concluded that reduced size and density of secretory granules is the main morphological standard responsible for extraordinary LH secretion from gonadotrophs.

Animals↗
PubMed1986

A quantitative immunohistochemical study on the pituitary LH gonadotrophs in the female Afghan pika after copulation.

The female Afghan pika is known as a species of copulatory ovulators exhibiting persistent estrus unless copulatory stimuli are employed. The plasma LH concentration rose quickly after copulation, peaked at 6 h and descended thereafter until 12 h. Before copulation (estrus), immunoreactive LH-containing cells of the pituitary in this species were filled with numerous large electron dense secretory granules, but the Golgi apparatus and the granulated endoplasmic reticulum were not well developed. One hour later the stainability of the cells was faint, their secretory granules were malls in size and in number, and were of low electron density. These alterations were the most predominant at 12 h after copulation. No exocytotic extrusion of secretory granules was observed throughout the experiment.

Animals↗
PubMed1986

Phasic changes in immunocytochemical stainability of pituitary luteinizing hormone cells associated with their ultrastructural changes during estrous cycle in the rat.

Changes in the immunoreactivity of pituitary luteinizing hormone (LH) cells and in their fine structure were studied in 4-day-cyclic female rats along with the radioimmunoassay of pituitary and serum LH. Pituitary LH increased during diestrus (DE) and in early proestrus (PE) to a maximal level at noon of PE, followed by a marked decrease by 2100 h PE. Serum LH stayed at low levels in estrus (E) and in DE, while they displayed a significant increase at PE. Light microscopic immunocytochemistry distinguished intensely and weakly stained cells using rat LH beta antiserum. The populations of intensely stained cells were 80% at PE, 30% at E and 75% at DE. This suggests that all of the LH cells do not secrete LH synchronously on the afternoon of PE. Immunoreactivity of LH cells was related to the amount of secretory granules stored in the cells as determined by the superimposition technique. Analysis of the LH storage site by the protein A-gold method confirmed that the small secretory granules, which accumulated in LH cells at DE or PE, certainly contain LH. At least two LH cell types were distinguished: one is the oval or polygonal cell with flattened rER numerous mitochondria, abundant small secretory granules (about 200 nm), a well developed Golgi complex, and a round nucleus. The other has similar structural characteristics along with large secretory granules which are more than 300 nm in diameter. At noon of PE almost all of the LH cells were the first type while the second ones were mainly found at DE or E. The relationship of these LH cell types of the male gonadotrophs is discussed.

Animals↗
PubMed1985

Changes in the nuclear uptake and retention of 3H-estrogen in gonadotrophs and lactotrophs as a function of age.

A quantitative autoradiographic immunocytochemical study was performed in which the nuclear uptake and retention of 3H-estradiol (3H-E2) by luteinizing hormone (LH) and prolactin (PRL) cells was examined in 19-21-year-old baboons. 3H-E2 concentrating cells were found in all of the three lobes of the pituitary in varying percentages (38.7%, pars distalis; 17.1%, pars intermedia; 6.3%, pars nervosa). Approximately 80% of PRL cells and nearly 100% of LH cells were labeled. A count of the number of silver grains over nuclei revealed a marked variation of the accumulation of 3H-E2 by LH cells and to a lesser extent in PRL cells. These results suggest functional heterogeneity among LH and PRL cells. The present results are discussed in relation to the physiological state of old animals.

Aging↗
PubMed1985

Fine structural and immunohistochemical studies of goat adenohypophysial cells.

The fine structure of each type of anterior pituitary cell in the male goat was studied through the application of a superimposition technique in which adjacent thick sections were used to identify individual cells beforehand by light-microscopic immunohistochemistry. A cone of the pars intermedia protrudes into the pars anterior, being surrounded by the narrow pituitary cleft; the immunohistochemical appearances of the cells forming the cone resemble those of the pars anterior. Several follicles appear in the pars anterior. Ultrastructurally GH cells resemble prolactin cells. The secretory granules of both types are spherical; the diameter of the former is about 340 nm, whereas that of the latter is about 440 nm. ACTH cells are polygonal in shape with secretory granules, about 180 nm in diameter, scattered throughout the cytoplasm. TSH cells, which are spherical in shape, contain the smallest secretory granules, 150 nm in diameter. The highly electron-dense LH cells contain numerous secretory granules about 210 nm in diameter. Their nuclei are irregular with incisures. Thus, the anterior pituitary cells of the goat are ultrastructurally characteristics and species-specific.

Adrenocorticotropic Hormone↗
PubMed1985

Does neonatal androgen modulate uptake and retention of 3H-estradiol in gonadotrophs and lactotrophs?

Castrated adult male and female and androgenized female rats (AS rats ) were injected i.v. with 3H-estradiol (E2). Nuclear uptake and retention of the 3H-steroid was examined in pituitary luteinizing hormone (LH) and prolactin (PRL) cells by the combined techniques of autoradiography and immunocytochemistry. About 80% of PRL cells were found to concentrate the radioactive steroid compound in all experimental groups, while 89%, 82% and 68% of LH cells were found to be labeled in AS rats, normal female and male rats, respectively. This suggests that there are subpopulations of LH or PRL cells that contain no or, if any, small numbers of E2 receptor. Statistical analysis revealed that PRL cells take up more radioactivity than LH cells in male rats, while there is no significant difference between female and AS rats. Variations in E2 uptake (coefficient of variation) was higher in LH cells than in PRL cells in male rats and in AS rats. In females, on t the contrary, coefficient of variation was larger in PRL cells. Thus the characteristics of nuclear uptake and retention of estradiol in LH and PRL cells appear to be modulated in part by neonatal androgen since the pattern found in AS rats is different than that found in AS rats is different than that found in normal male and female rats.

Animals↗
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↗