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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

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

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↗
PubMed1992

Marked alternans of the elevated ST segment during occlusion of the left anterior descending coronary artery in percutaneous transluminal coronary angioplasty: clinical background and electrocardiographic features.

To investigate the clinical background and the electrocardiographic features of marked alternans of the elevated ST segment during coronary angioplasty, we examined 12-lead electrocardiograms recorded continuously during occlusion of the left anterior descending coronary artery by balloon inflation in 41 patients. The incidence of marked ST alternans was 27% of 41 patients and 15% of 117 balloon occlusions. The incidence decreased progressively from the first to the third occlusion. The time course of ST alternans was determined. Compared with patients without ST alternans, patients with ST alternans had a shorter history of angina, less severe stenosis of the target lesion before coronary angioplasty, more leads showing ST elevation during occlusion, higher ST elevation during occlusion and lower incidence of previous myocardial infarction in the left anterior descending coronary arterial area. ST alternans recorded on the surface electrocardiogram may thus be considered a marker of acute severe and extensive myocardial ischemia.

Adult↗
PubMed1992

Dynamic aspects of AMPs in the kidney in physiological conditions--their metabolism and turnover.

The past few decades have witnessed a number of studies on AMPs in the kidney. Almost all of these studies, however, have dealt with the quantitative and qualitative analysis of AMPs in the kidney using biochemical techniques, whereas the dynamic aspect of AMPs in the kidney has been overlooked and its metabolism and turnover have never been emphasized. On the other hand, the kidneys removed from humans and experimental animals revealed a wide variety in interstitial tissue in the medulla microscopically and in the papilla of the kidney macroscopically. The reasons for these variations in the medulla, its mechanism and the matrical component have not yet been clarified. In an effort to clarify these points, we herein describe our study on the dynamic aspect of AMPs in kidney histologically in relation to their biological turnover which we employed several staining methods. Our results revealed that there was a very active turnover of AMPs present in the kidney confirming that the kidney plays an important role physiologically in AMP metabolism. The degree of the turnover of AMPs in the kidney varies from case to case. In the active phase, AMPs are excreted in the glomerulus and reabsorbed in the proximal portion of the collecting tubules. Most of the absorbed AMPs are finally drained through the lymphatic vessels in situ and a few are excreted into the urine. Contrary cases have been demonstrated, however, only were a few AMPs were noted throughout the nephrons in the kidney. AMP turnover in the kidney is unexpectedly remarkable. The medulla, which has been considered less important, in fact, plays a key role in AMP metabolism.

Alcian Blue↗
PubMed1992

Granulocyte-colony stimulating factor facilitates the restoration of resistance to opportunistic fungi in leukopenic mice.

Administration of recombinant human granulocyte-colony stimulating factor (G-CSF), which induces hemopoietic precursor cells to proliferate and differentiate into neutrophils, protected leukopenic mice infected with opportunistic fungi. Mice were injected with cyclophosphamide and were then subcutaneously (s.c.) or intravenously (i.v.) administered 15-120 micrograms G-CSF kg-1 day-1 for 3 days. The number of peripheral blood neutrophils in the G-CSF treated mice was significantly increased 48 h after G-CSF administration. All leukopenic mice infected with either Candida albicans, Cryptococcus neoformans or Aspergillus fumigatus were significantly protected by treatment with the G-CSF. Moreover, G-CSF treatment caused a decrease in the number of viable yeasts in kidneys of Candida infected mice. These data suggest that prophylactic therapy with G-CSF may be useful against fungal infections in an immunocompromised host.

Animals↗
PubMed1992

Daily intakes of 232Th and 238U in Japanese males.

Diet samples were collected by a duplicate portion method from 31 locations in Japan and were analyzed by inductively coupled plasma mass spectrometry. Average daily intakes per adult male were estimated at 1.7 mBq for 232Th and 8.8 mBq for 238U.

Adult↗