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Biomedical subjects

K Koshiyama

Publications and source records attributed to K Koshiyama.

At least 19 recordsLinked to original sources
PubMed2001

Heparin-binding outer membrane protein of chlamydiae.

As an intracellular pathogen, the mechanism by which Chlamydia invade eukaryotic cells represents a cornerstone to understanding chlamydial biology. The ability of chlamydiae specifically to bind heparan sulphate or heparin and the association of this ability to bind and enter mammalian host cells was approached by searching experimentally for chlamydial outer membrane proteins that bind heparin. The 60 000 molecular weight cysteine-rich outer membrane complex protein, OmcB, bound heparin. The ability of OmcB to bind heparin was supported by mapping the region of the protein with heparin-binding capacity and demonstrating that an OmcB synthetic 20-mer peptide from this region specifically bound heparin. Surface localization of OmcB was shown using monospecific antisera specific to the 20-mer OmcB peptide that bound the surfaces of elementary bodies (EB) and by heparin-binding peptide cross-linking of EB surface proteins.

Amino Acid Sequence↗
PubMed2000

Chlamydia-dependent biosynthesis of a heparan sulphate-like compound in eukaryotic cells.

One hypothesis for the mechanism of chlamydial interaction with its eukaryotic host cell invokes a trimolecular mechanism, whereby a Chlamydia-derived glycosaminoglycan bridges a chlamydial acceptor molecule and a host receptor enabling attachment and invasion. We show that a heparan sulphate-specific monoclonal antibody specifically binds a glycosa-minoglycan localized to the surface of the chlamydial organism and effectively neutralizes infectivity of both C. trachomatis and C. pneumoniae. In addition to the ability of this antibody to neutralize infectivity, direct visualization using immunofluorescence demonstrated staining of chlamydial organisms localized to the intracellular vacuole. The chlamydial-associated glycosaminoglycan was specifically labelled with [14C]-glucosamine, and the labelled compound was immunoprecipitated and resolved by gel electrophoresis. The chlamydial-associated glycosaminoglycan is a high-molecular-weight compound similar in size to heparin or heparan sulphate and was sensitive to cleavage by heparan sulphate lyase. These data demonstrate that a glucosamine-containing sulphated polysaccharide is produced within the intracellular vacuole containing chlamydiae and is a target for antibody-mediated neutralization of infectivity.

Animals↗
PubMed2000

Eukaryotic cell uptake of heparin-coated microspheres: a model of host cell invasion by Chlamydia trachomatis.

Using polystyrene microspheres coated with heparin or heparan sulfate, it was shown that coated microspheres specifically bound eukaryotic cells and were endocytosed by nonprofessional phagocytic cells. Coated microspheres displayed properties of binding to eukaryotic cells that were similar to those of chlamydiae, and the microspheres were competitively inhibited by chlamydial organisms. Endocytosis of heparin-coated beads resulted in the tyrosine phosphorylation of a similar set of host proteins as did endocytosis of chlamydiae; however, unlike viable chlamydial organisms, which prevent phagolysosomal fusion, endocytosed beads were trafficked to a lysosomal compartment. These findings suggest that heparin-coated beads and Chlamydia trachomatis enter eukaryotic cells by similar pathways.

Bacterial Adhesion↗
PubMed1976

Influence of surgical stress under general anesthesia on serum gonadotropin levels in male and female patients.

Effects of surgical stress under the same general anesthesia (nitrous oxide, oxygen and halothane following induction with thiopental and succinylcholine chloride) on serum LH levels were studied in 18 postmenopausal females, 15 menstruating females and 17 males. In addition, serum FSH levels in female patients and testosterone levels in male patients were estimated. As controls without surgery and anesthesia, serum levels of LH, FSH and testosterone were estimated at identical time intervals to the experimental group in 15 normal postmenopausal females, 15 normal menstruating females and 10 normal males. In male patients, serum LH levels at 30 min and 1 hr after onset of anesthesia increased significantly over those of pre-anesthesia, while no significant intra-operative increase in LH levels was found in female patients. In male and female patients, the LH levels decreased slightly 5-6h and 2 days after onset of anesthesia, though the decreases were not statistically significant except in postmenopausal females. On the 7th postoperative day, the LH levels returned toward the baseline. In female patients, no significant intra-operative changes in FSH levels were found. In male patients, there were significant intra- and post-operative decreases in testosterone levels. In control subjects, no significant changes in serum levels of LH, FSH and testosterone were demonstrated. These observations suggest that significant intraoperative increases in serum LH levels occur in males but not in females.

Adult↗
PubMed1975

Effects of general anaesthesia and severity of surgical stress on serum LH and testosterone in males.

Significantly decreased levels of serum testosterone from the pre-anaesthesia level were found during and up to 7 days following major surgery under general anaesthesia (nitrous oxide, oxygen and halothane following induction with thiopental and succinylcholine chloride) in 18 male patients. On the other hand in the same patients, the serum lutenizing hormone (LH) increased significantly from the pre-anaesthesia level 30 min and 1 h after the beginning of anaesthesia. A slight increase in LH level was also noted on the 7th post-operative day. The determinations of serum testosterone and LH in fiberoptic bronchoscopy under the same general anaesthesia as that used in surgery or local anaesthesia in 26 male patients, revealed that the change in the serum LH during and following surgery seemed to be mainly induced by the general anaesthesia and that the rate of decrease in the serum testosterone may be related to the severity of surgical stress including the anaesthesia. The rate of increase in serum testosterone following the injection of gonadotrophin in 20 males on the 6th post-operative day was similar to that in 10 pre-operative males. The effects of pulmonary lobectomy on serum testosterone and urinary steroids were also studied in 6 males under adrenal suppression with dexamethasone. On the 6th post-operative day, the urinary aetiocholanolone plus androsterone and serum testosterone were found to be half the level of those on the pre-operative day, while the urinary 5beta-pregnane-3alpha, 17alpha, 20alpha-triol remained unchanged. These observations in human are not inconsistent with the report of Tcholakian and Eik-Nes (1971) in dogs namely that a shift in androgen biosynthetic pathway is present in the testis under surgical stress.

17-Ketosteroids↗