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Biomedical subjects

H Yamaguchi

Publications and source records attributed to H Yamaguchi.

At least 19 recordsLinked to original sources
PubMed1992

Different patterns of cell volume regulation in hyposmotic media between attached and suspended HeLa cells.

Both attached and suspended HeLa cells swelled in a medium of a hypotonic osmolality of 235 mosmol/kg H2O. When the osmolality was further decreased to 166 mosmol/kg H2O, attached cells instantly swelled and then rapidly lost water and K+, followed by slow gains of them. Suspended cells instantly swelled and then K+ loss and regulatory volume decrease (RVD) occurred. Neither 0.1 mM ouabain nor 10 mM TEA changed the water loss of attached cells, whereas ouabain inhibited RVD of suspended cells. Quinine (1 mM) inhibited water losses from both cells and comparison of the losses implies stronger activation of K+ channel in attached cells than in suspended cells. Omission of medium Ca2+ or addition of 10 mM BaCl2 inhibited RVD in part. These results suggest that hyposmotic stress induces net water loss from attached cells, associated with K+ release through the Ca(2+)-dependent K+ channel. Suspended cells osmotically swell, followed by RVD with K+ and Na+ releases through the K+ channel and Na(+)-pump, respectively. The different patterns of volume changes may relate to the difference of activity or time of activation of the K+ channel between both cells.

Barium↗
PubMed1992

Growth of human cultured cells exposed to a non-homogeneous static magnetic field generated by Sm-Co magnets.

A static magnetic field, with a strong spatial gradient, was established on the surface of cell culture dishes by use of a gilded iron needle set vertically above an Sm-Co magnet. The calculated magnetic flux density was more than 1.5 T at the center of the needle tip, and the products of the flux density and its gradient were about 200 and 60 T2/m at distances of 0.1 and 0.3 mm, respectively, from the center. The DNA content, DNA synthesis and labeling index of cultured cells located within 0.1 mm from the center of the needle, and the growth rate of cells located within 0.3 mm from the center, were measured. HeLa cells grew at a normal rate for 96 h in the magnetic field and showed no significant change in shape, detectable by scanning electron microscopy. The growth of HeLa cells was not influenced by exposure to the magnetic field. Similarly, exposure for 48 h to the magnetic field had no effect on growth of normal human gingival fibroblasts (Gin-1). The DNA content, assayed by microfluorometry of the nuclei of both types of cells stained by the Feulgen reaction, was not significantly different from that of controls. Moreover, exposure to the magnetic field had no effect on DNA synthesis or the labeling index of HeLa cells assayed by autoradiography of incorporated [3H]thymidine. It is concluded that a non-homogeneous magnetic field of the intensity and the gradient used in this study does not significantly influence the growth of HeLa cells or Gin-1 cells.

Cells, Cultured↗
PubMed1992

Localization of smg p25A/rab3A p25, a small GTP-binding protein, at the active zone of the rat neuromuscular junction.

smg p25A is a small G protein which has been suggested to regulate neurotransmitter release from the synapses. We investigated here the ultrastructural localization of this small G protein in the rat neuromuscular junction by an immunoperoxidase method. The results showed that smg p25A was distributed non-uniformly on the presynaptic plasma membrane and among the synaptic vesicles with the focal accumulation on the discrete presynaptic sites which corresponded to the active zones, the regions of the presynaptic plasma membrane specialized for the exocytosis of the synaptic vesicles. This unique distribution of smg p25A suggests that it plays an important role in the attachment and fusion of the synaptic vesicles with the active zones.

Animals↗
PubMed1992

High in vitro-in vivo correlation of drug response using sponge-gel-supported three-dimensional histoculture and the MTT end point.

The in vitro sponge-gel-supported three-dimensional histoculture chemosensitivity assay (Hoffman assay) allows the in vivo-like culture of human tumors. In this study, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H tetrazolium bromide (MTT) end point was applied to the Hoffman assay in an attempt to increase in vitro-in vivo correlation. The chemosensitivities of 16 human tumor lines were determined in vitro by the histoculture assay, and retrospectively correlated to their in vivo chemosensitivity as xenografts in nude mice. The in vitro test was considered to be positive if tumor-cell MTT reduction activity was lowered by more than 50%. The cutoff drug concentrations to determine sensitivity in vitro were determined for mitomycin C, doxorubicin, 5-fluorouracil and cisplatin. Using these cutoff drug concentrations in vitro we found, as a function of time of exposure, a strong correlation between serum drug concentrations found in nude mice given maximum tolerated doses and drug concentrations found in the histoculture media in vitro, thereby establishing a relationship between the amounts of drugs to which tumors were exposed in vivo and in vitro. The overall correlation rate of the efficacy results of the drug-response assay to in vivo chemosensitivities was 89.8%, with 90.0% true-positive and 89.7% true-negative rates, 81.7% sensitivity and 94.6% specificity, thereby indicating potential clinical use for tumor histoculture with the MTT end point.

Animals↗
PubMed1992

Intramural metastasis of thoracic esophageal carcinoma.

Of 393 patients with squamous-cell carcinoma in the thoracic esophagus, 60 were found by histologic examination to have intramural metastasis. Metastases in 50 of these were identified by gross inspection. There appeared to be no preference for location proximal to the primary lesion. Eighteen patients had metastasis to the gastric wall, which suggested the existence of communicating lymphatic channels between the wall of the esophagus and the stomach. All 60 primary tumors invaded beyond the submucosa. These 60 patients (group A) were compared with a group of matched control patients without intramural metastasis (group B). The tumor size in group A was significantly larger than in group B (p less than 0.01). The number of patients with lymph-node metastasis was significantly higher in group A (p less than 0.01), and the average number of positive nodes in group A was greater than in group B (p less than 0.01). Recurrent disease in the mediastinal lymph nodes and in the liver is characteristic of group A. The survival curve for patients in group A was significantly lower than that for group B (p less than 0.001). Conventional radiotherapy or chemotherapy after surgery were ineffective in improving prognosis. These results indicate that the presence of intramural metastasis is an important factor to consider when evaluating the prognosis of patients with squamous-cell carcinoma of the esophagus.

Carcinoma, Squamous Cell↗
PubMed1992

Enhancement of host resistance to opportunistic infections by ubenimex (bestatin).

Ubenimex is a low molecular biological response modifier (BRM) which has been demonstrated to have antitumor and immunomodulatory activities. In this study, the effect of ubenimex on infection with Candida albicans was investigated in normal and immunosuppressed mice, and it showed a prophylactic effect. In normal mice, ubenimex prolonged survival time in a dose-dependent manner. In immunosuppressed mice treated with cyclophosphamide 4 days before infection, ubenimex at 5 mg/kg for 5 days significantly increased the number of survivors. Significant improvement in peritoneal leukocyte counts and in function of neutrophils including phagocytosis and release of activated oxygen was observed in ubenimex-treated mice. These results indicate that ubenimex is a potent BRM for prevention against opportunistic infections.

Animals↗
PubMed1992

BRM activities of low-toxic Bordetella pertussis lipopolysaccharides.

A low-toxic lipopolysaccharide (BP-LPS) was isolated from killed Bordetella pertussis (Tohama strain). LD50 of BP-LPS was about 0.8 mg/mouse which was about 10-fold higher than the LD50 of E. coli-LPS(80 micrograms/mouse). Toxicity measured by decrease in body weight of BP-LPS-injected mice was similarly low. BP-LPS had strong antitumor activities against various murine syngeneic tumors, and its systemic administration caused clear regression of such as MM46 mammary carcinoma and Meth A fibrosarcoma. It is noteworthy that a tolerable dosage of BP-LPS (375 micrograms/mouse) showed clear antitumor activity against MH134 hepatoma, which is known to be insusceptible to usual types of BRM including bacterial LPS. These findings suggest that BP-LPS is a promising candidate as an antitumor agent for clinical use. Biological activities of BP-LPS were examined and compared with those of toxic LPS extracted from Escherichia coli and other enterobacteria. Activation or stimulation of macrophages and lymphocytes by these LPS, including TNF induction, was found to be similar. However, activation of human or murine neutrophils, as estimated by neutrophil-adherence assay in vitro, though induced by all other toxic LPS tested, was not induced by BP-LPS. This inability of BP-LPS to activate neutrophils is assumed to be related to its low toxicity.

Animals↗
PubMed1992

Comparison of magnetic resonance imaging and computed tomography in the local assessment of osteosarcoma.

We have compared the value of magnetic resonance imaging (MRI) with computed tomography (CT) in assessing the extent and the localization of osteosarcomas. Twenty patients were examined by both systems, and the results related to the clinical and histological findings. While both investigations are valuable, MRI may be more useful for defining the local extent of an osteosarcoma.

Adolescent↗
PubMed1992

Ultrastructural localization of Alzheimer amyloid beta/A4 protein precursor in the cytoplasm of neurons and senile plaque-associated astrocytes.

The ultrastructural localization of amyloid beta/A4 protein precursor (APP) in the brains of control and Alzheimer's disease patients was examined immunohistochemically using antisera against the N and C termini of APP. In both control and Alzheimer brains, immunoreaction for APP was seen in the cytoplasm of most neurons, on plasma membranes, outer membrane of mitochondria, granular substance and neurofilaments. Cell bodies and foot processes of astrocytes, containing glial filaments, were also labeled. In primitive and classic type senile plaques, APP immunoreaction products were localized in the astroglial processes that surrounded the amyloid mass of the senile plaques. Swollen degenerating neurites in the senile plaques were also labeled. Amyloid fibrils were negative with APP antisera.

Aged↗
PubMed1992

Changes in the concentrations of Na+, K+ and Cl- in secretion from the skin during progressive increase in exercise intensity.

A simple method for sampling skin secretion in 1-min periods was developed for investigating the effects of progressive increases in exercise intensity on Na+, K+ and Cl- secretions from the skin of the forearm. Ten healthy male subjects performed exercise consisting of eight stepwise increases in intensity from 50 to 225 W, with a 25-W increase at each step. Exercise at each step was for 3 min followed by a 1-min recovery period. Samples of blood and skin secretion were taken during the recovery period. Significant positive correlations were found between the mean concentrations of Na+ and Cl- and between those of K+ and Cl- in the skin secretion. The concentrations of electrolytes in the skin secretion also showed significant correlations with the blood lactate concentrations. The inflection points for secretions of Na+, K+ and Cl- were 4.04, 3.61 and 3.83 mmol.l-1 of blood lactate; 64.42, 61.96 and 62.14% of maximal oxygen consumption (VO2max); and exercise intensities of 123.01, 117.65 and 125.07 W, respectively. No significant differences were observed between the value of 67.27% of VO2max or 134.00W at the onset of blood lactate accumulation (OBLA) and the inflection points. From these results we concluded that changes in electrolyte concentrations in skin secretion during incremental exercise according to this protocol were closely related with the change in the blood lactate concentration, and that the inflection points for electrolytes may have been near the exercise intensity at OBLA.

Adult↗
PubMed1992

Anorexia nervosa responding to zinc supplementation: a case report.

An emaciated 16-year-old female with anorexia nervosa was hospitalized for treatment of vomiting, epigastralgia and diarrhea. The finding of a taste disorder, low serum alkaline phosphatase activity and relatively low serum zinc level strongly suggested a zinc deficiency. Zinc was initially administered intravenously (40 mumol/day) for 7 days, then orally (15 mg elemental zinc/day) for about 60 days. Her digestive symptoms disappeared after the second day of intravenous treatment and she began to gain weight. She rapidly regained her normal weight after one month of receiving the oral zinc supplementation. Both exocrine pancreatic function and intestinal absorption were improved by the prolonged oral administration of zinc. In such cases zinc supplementation may be a therapeutic option in addition to psychologic and other approaches to management.

Adolescent↗
PubMed1992

Studies on apolipoprotein(a) phenotypes. Part 2. Phenotype frequencies and Lp(a) concentrations in different phenotypes in patients with angiographically defined coronary artery diseases.

In the present paper, we have evaluated serum Lp(a) concentrations, the frequencies of Lp(a) phenotypes and alleles and the association between the Lp(a) phenotypes and serum Lp(a) levels in 470 patients with angiographically defined coronary artery disease (CAD). Serum Lp(a) concentrations were significantly increased in proportion to the number of diseased vessels in the CAD patients. The frequencies of Lp(a) phenotypes in the CAD patients were significantly different from those in healthy subjects. In particular, the frequency of double-band phenotypes was higher in the CAD group. The frequencies of Lp(a) alleles in the CAD patients, however, were not significantly different from those in the healthy subjects. There was a strong inverse relationship between the apparent molecular weights of apo(a) isoforms and serum Lp(a) concentrations. Lp(a) levels in the CAD patients were higher than those in the healthy subjects with the same phenotype. The present results suggest that it is important to consider some posttranslational or environmental modifications and other factors, in addition to the genetic factor, when assessing contributions to plasma Lp(a) levels.

Alleles↗
PubMed1992

Radical-mediated modification of deoxyguanine and deoxyribose by luteoskyrin and related anthraquinones.

When cultured Reuber hepatoma H4-II-E and fibroblast Balb/3T3 cells were exposed to various concentrations of 5 derivatives of anthraquinones, luteoskyrin, a bis-anthraquinoid hepatocarcinogenic mycotoxin, exhibited the highest cytotoxicity to these cell lines. The content of 8-hydroxydeoxyguanine residues in the DNA of H4-II-E cells was dose- and time-dependently increased by luteoskyrin. The tumorigenic anthraquinones such as rugulosin and danthron also slightly elevated the level of this modified DNA base, while no such modification was observed with chrysophanol and emodin. Detailed experiments with luteoskyrin have demonstrated the formation of 8-hydroxydeoxyguanine and the degradation of deoxyribose into thiobarbituric acid-reactive products in the presence of ascorbic acid. These findings suggest the possible involvement of anthraquinone-derived hydroxy radicals for the modification of DNA base and deoxyribose.

3T3 Cells↗