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Biomedical subjects

K Nitta

Publications and source records attributed to K Nitta.

At least 163 records · Page 9Linked to original sources
PubMed1995

High glucose modulates albumin permeability across glomerular endothelial cells via a protein kinase C-dependent mechanism.

To investigate the mechanism of glomerular endothelial response to high glucose, an in vitro model of the glomerular endothelial barrier was established in which transfer of fluorescein-labeled albumin across confluent monolayers of immortalized bovine glomerular endothelial cells (GEN) grown on polycarbonate membranes was measured. We first examined the effects of increased concentrations of D-glucose on albumin permeability across GEN monolayers and further investigated the role of protein kinase C (PKC) in the regulation of glucose-induced changes in endothelial barrier function. Incubation with 30 mM D-glucose increased albumin permeability more than those with 10 mM D-glucose. Albumin permeability incubated with 10 mM D-glucose plus 20 mM mannitol was not significantly different from those with 10 mM D-glucose, indicating that the increase in albumin permeability induced by 30 mM D-glucose was not due to high osmolar stimuli. A protein kinase C (PKC) inhibitor, H-7 (25 microM) significantly reduced the permeability-increasing effects of D-glucose. Lactate dehydrogenase release from endothelial cells was not significantly increased above baseline after incubation with 10 mM or 30 mM D-glucose. These results suggest that elevated concentrations of glucose activates PKC, resulting in an increase in albumin permeability across GEN.

Animals↗
PubMed1995

Expression of intercellular adhesion molecule-1 on cultured glomerular endothelial cells by pro-inflammatory cytokines and lipopolysaccharide.

Infiltration of leukocytes and mononuclear cells into the glomeruli is an early pathological finding in human and experimental glomerulonephritis. However, the cellular and molecular basis for cell infiltration into the glomeruli is not yet completely understood. In addition, there is little information on the expression of intercellular adhesion molecule-1 (ICAM-1) on glomerular cells. In the present study, we investigated the expression of ICAM-1 on cultured bovine glomerular endothelial cells (GEN) and its regulation by the pro-inflammatory cytokines, interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and lipopolysaccharide (LPS). Immunocytochemical staining showed that ICAM-1 molecules were constitutively expressed on the surface of GEN. In flow cytometric and ELISA analyses, ICAM-1 molecule expression on GEN was significantly upregulated by IL-1 beta, MCP-1 and LPS in a dose-dependent manner, but not by IL-6. LPS was the most potent inducer of ICAM-1 molecule expression on GEN. The effects of IL-1 beta, MCP-1 and LPS were observed as early as 4 h and reached a maximal level by 18 h. These results suggest that ICAM-1 on GEN can participate in the infiltration of mononuclear cells into glomeruli in human and experimental glomerulonephritis.

Animals↗
PubMed1995

Analysis of the expression of cell surface antigens and intercellular adhesion molecules on lymphocytes in CAPD patients.

The aim of the present study was to assess immunological aspects in patients on continuous ambulatory peritoneal dialysis (CAPD). The CAPD patients were divided into two groups. Group A consisted of patients in which high-somolar dialysate was used infrequently, and group B consisted of patients in which high-osmolar dialysate was used frequently. We characterized cell populations in the peritoneal effluent (PE) of CAPD patients. Analysis of the nucleated cell composition revealed that one-third of the PE cells were lymphocytes. Flow cytometric analysis of the surface antigen expression on lymphocytes revealed that the proportion of helper/inducer T-cells was lower in PE than in peripheral blood (PB). By contrast, the rates of DR antigen expression on T-cells and CD45RO antigen expression on helper/inducer T-cells (memory T-cells) were higher in PE than in PB. However, there were no statistically significant differences between the rates of expression of any lymphocyte surface antigens in the two groups. Expression of intercellular adhesion molecules, such as ICAM-1 and LFA-1, was higher in PE than in PB. It is of interest that the expression of ICAM-1 and LFA-1 on T-cells in PB was significantly higher in group B than in group A. In summary, there is an increase in memory T-cells in the PE and up-regulation of intercellular adhesion molecules of PE lymphocytes of CAPD patients. The up-regulation of intercellular adhesion molecules is also observed in PB lymphocytes in whom high-osmolar dialysate is used frequently.

Adult↗
PubMed1995

[A case of chronic progressive radiation myelopathy with cavity formation in the thoracic spinal cord].

A 70-year-old man was admitted to our hospital in March 1994 because of subacute progressive paraparesis and sensory impairment below the level of the second thoracic (TH 2) spinal cord on the right side. He had received radiation therapy (48 Gy) on his neck and mediastinum eight years previously due to adenocarcinoma of the right upper lung. Blood chemistry, CT of the spine, bone and gallium scintigraphy were unremarkable. In magnetic resonance imaging (MRI) of the thoracic cord, the gadolinium (Gd)-enhanced T1-weighted image showed abnormal signal intensities from Th 3 to Th 4 of the spine. Myelography revealed no abnormalities. Three months later, the patient became a complete spinal man below the level of Th 4. Gd-enhanced MRI of the thoracic cord, performed eleven months later, showed formation of a spindle-shaped cavity from Th 2 to Th 5 of the spine surrounded by a ring-shaped enhanced cord. Chronic progressive radiation myelopathy (CPRM) was diagnosed based on these clinical and MRI findings. This was a rare case in which MRI-confirmed cavity formation in the spinal cord appeared in a patient with CPRM.

Aged↗
PubMed1994

The effects of goshajinkigan, a herbal medicine, on subjective symptoms and vibratory threshold in patients with diabetic neuropathy.

Goshajinkigan, a herbal medicine, has long been used in Japan to alleviate the subjective symptoms of diabetic neuropathy; however, its effects have not been confirmed objectively. We evaluated its effects on subjective symptoms and on vibration sensation in patients with diabetic neuropathy. The oral administration of 7.5 g/day of Goshajinkigan for 3 months (treatment period) relieved subjective symptoms of numbness in 9 of 13 patients. When the drug was discontinued for 2 months as a washout period, the subjective symptom worsened in 7 of 13 patients. Chi-square analysis revealed significant effects of Goshajiniagan on subjective symptoms (P < 0.001 for numbness and P < 0.05 for cold sensation). Vibration sensation was evaluated by measuring vibratory threshold using an SMV-5 vibrometer. There were significant changes in vibratory thresholds by paired t-test (P < 0.05) both in the upper and the lower extremities during the treatment and washout periods. Chi-square analysis also revealed a significant effect of Goshajinkigan on vibratory threshold (P < 0.01). There was no significant change in glycosylated hemoglobin as a whole during the study. These observations confirm that Goshajinkigan relieves subjective symptoms and demonstrate that it improves vibration sensation in patients with diabetic neuropathy.

Administration, Oral↗
PubMed1994

Inhibition of cell proliferation by Rana catesbeiana and Rana japonica lectins belonging to the ribonuclease superfamily.

Two frog egg lectins [Rana catesbeiana lectin (SBL-C) and Rana japonica lectin] preferentially agglutinate a large variety of human and animal tumor cells but not blood cells, lymphocytes, or fibroblasts. These lectins belong to the superfamily of pyrimidine base-specific RNases. The two lectins bound to a heparin-Sepharose column and were eluted from the column by an increase of NaCl molarity. Both their tumor cell-agglutinating activity and RNase activity were inhibited by heparin, and also by polyamines, such as spermine. Both lectins inhibited P388 leukemia cell proliferation. The inhibitory activity of SBL-C was blocked by addition of heparin. SBL-C inhibited protein synthesis by P388 cells, but RNase A did not. No lectin-induced antiproliferative effect was observed after sialidase treatment of cells. The antiproliferative activity of SBL-C was also inhibited by ammonium chloride treatment. These results suggest that internalization of the lectins by lectin receptor (sialoglycoconjugate)-mediated endocytosis is followed by cell death due to inhibition of protein synthesis. Administration of SBL-C i.p. delayed time to death in mice receiving i.p. transplants of Sarcoma 180 and Mep II cells.

Agglutination↗
PubMed1994

Characterization of a Rana catesbeiana lectin-resistant mutant of leukemia P388 cells.

Sialic acid-binding lectin (SBL-C) from Rana catesbeiana eggs inhibits the growth of tumor cells such as P388 and L1210 leukemia cells (K. Nitta et al., Cancer Res., 54: 920-927, 1994). Here we report the establishment of an SBL-resistant P388 variant cell line, RC-150. Both P388 and RC-150 cells were agglutinated by SBL-C; however, growth of RC-150 cells was unaffected by SBL-C. Cytoplasmic free Ca2+ concentration and transglutaminase activity of RC-150 cells were 0.5 (110 nM) and 3 times (0.62 nmol/mg/min) as high as those of P388 cells, respectively. Microvilli and microplicae were observed on the surface of P388 cells by scanning electron microscopy but were rarely seen on RC-150 cells. Dansylcadaverine-labeled SBL-C bound to both P388 and RC-150 cells. Binding of SBL-C to these tumor cells appears to be mediated by two species of wheat germ agglutinin-stained cell membrane sialoglycoproteins. Labeled SBL-C entered P388 but not RC-150 cells, suggesting that internalized SBL-C acts as an inhibitor of cell proliferation.

Agglutination↗
PubMed1994

The use of a human dura mater allograft for the repair of a contaminated abdominal wall defect: report of a case.

A case report of an infected full-thickness abdominal wall defect treated successfully with a human dura mater allograft is presented. A review of the literature and a discussion of prosthetic abdominal wall repair is also included. A 46-year-old woman presented with multiple small bowel perforations and a large abdominal wall defect due to a motor vehicle collision. A gamma-irradiated human dura mater prosthesis was used to repair the large abdominal wall defect which had been infected by a jejunal fistula. After more than 4 years of follow-up, the patient is free of complications, including wound infection, herniation, and ileus. The human dura mater allograft is thus considered to be a useful prosthesis for repairing potentially infected wounds.

Abdominal Muscles↗
PubMed1994

Impairment of surfactant activity and ventilation by proteins in lung edema fluid.

We investigated the effects of lung edema protein on ventilatory mechanics with special reference to surfactant activity. The edema fluid was obtained from hyperoxia-exposed adult rabbits. In immature newborn rabbits that could not be artificially ventilated at an insufflation pressure of 25 cm H2O, mean tidal volumes of > 27 ml/kg were obtained by supplementation with a natural surfactant (S-alone) or natural surfactant mixed with lung edema fluid (EF), the edema protein-to-surfactant ratio of which was < or = 5.6. A mixture with a ratio of 11.2 (11.2-EF/S), however, decreased the volume to 10.9 ml/kg (P < 0.05 vs S-alone). Surfactant mixed with isolated albumin at a concentration equal to that in 11.2-EF/S decreased the tidal volume to 8.6 ml/kg (NS vs 11.2-EF/S), and with isolated fibrinogen lowered it to 18.1 mg/kg (P < 0.05 vs S-alone). We conclude that lung edema fluid impairs ventilation through surfactant inactivation when the protein-to-surfactant ratio increases, and that albumin and fibrinogen are the main causes of this impairment.

Albumins↗
PubMed1994

Earth environment and Closed Ecology Experiment Facilities.

The Closed Ecology Experiment Facilities, CEEF, one of the Environmental Time Machine, is now planning to be constructed in the northern part of Japan with an eye to study the effect of atomic power industries on the local environment. This CEEF can be used not only for investigating the environmental problems related with atomic power industries but also for various environmental problems such as the habitation in lunar & Mars bases and the development of mathematical model to predict the change and change rate of earth parameters. Researches on earth environment and earth system science are discussed with use of CEEF. Preliminary experiments using a small growth chamber showed different results from those estimated by Simple Biosphere Model being used in the climate estimation.

Carbon Dioxide↗
PubMed1994

Needs of physiological and psychological research using artificial gravity.

In the next century, mankind will expand its activity to the moon and Mars. At that time, humans will be exposed to a low and micro-gravity environment in long term which causes physiological and psychological problems. The authors propose an artificial gravity space station for a research laboratory on human physiology and psychology at various gravity levels. The baseline specifications and the configuration of the space station are shown. Reviewing the history of manned space flight, the necessity of the research on an artificial gravity space station is discussed, including themes of research to be conducted on the station and the application of its results. Technical issues for realization of the space station such as environmental factors, system function and assembly scenario are also discussed.

Aerospace Medicine↗
PubMed1994

CELSS: possible contributions to earth science program and others.

CELSS technology, composed of various subsystems designed to stabilize the environment in closed space can be used to construct the Closed Ecology Experiment Facility. The Closed Ecology Experiment Facility has the character of an Environmental Time Machine. Many environmental researches of studies will, it is proposed, be conducted using this facility. The concept of Closed Ecology Experiment Facility is described, and several research items related to earth science potentially to be conducted using this facility are indicated. As an example of the application, an improved model of climate estimation is discussed.

Animals↗
PubMed1994

Measurement of rice crop metabolism using closed-type plant cultivation equipment.

In order to determine a required plant cultivation area which can sustain human life in a closed environment, the material circulating measurement system including a Closed-type Plant Cultivation Equipment (CPCE) in which the metabolic data of plants can be accurately measured has been constructed. According to results from cultivation experiments using rice, the harvest index was 29.9% for 110 days, and the required crop area to supply food, oxygen and water for one person was calculated to be about 111m2, 36m2 and 0.9m2, respectively.

Air Conditioning↗
PubMed1994

Tumour affinity of 203Pb-chloride: comparison with 67Ga-citrate and 201Tl-chloride.

The radionuclide 203Pb decays completely by electron capture to stable 203Tl with a half-life of 52 h. The primary radiation from the decay is gamma-ray radiation 280 keV (80%). 203Pb is produced easily from the natural metal thallium by the method described below. 203Pb-chloride is a promising imaging agent for tumour scanning because of the large retention value for tumour tissue and the small value for normal organs, but the large value for the kidney and bone is a shortcoming when considering it as an imaging agent. The retention value of 203Pb in tumour tissue is larger than that of 201Tl and smaller than that of 67Ga. The tumour/inflammatory lesion retention ratio for 203Pb is very large in comparison with those for 67Ga and 201Tl. 203Pb accumulates to a large extent in viable tumour tissue, and less in necrotic tumour tissue and in inflammatory lesion. Therefore, 203Pb-chloride is far better for visualization of viable tumour tissue than 67Ga and 201Tl if the large retention values for the kidney and bone were reduced.

Animals↗
PubMed1994

Glomerular endothelial cells in culture express and secrete vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) is a specific growth factor for endothelial cells, and its abundant expression has been reported in kidney glomeruli. In this study, we focused on glomerular endothelial cells (GEN) as a possible source of VEGF secretion and sought to uncover a potential autocrine role of VEGF for GEN. Ribonuclease protection assay demonstrated VEGF mRNA expression in cultured GEN, and 46-kDa VEGF protein was detected in the conditioned medium by immunoblot analysis using polyclonal antibody raised against the NH2-terminal portion of VEGF. Removal of fetal bovine serum (FBS) from the culture medium for 2 h decreased VEGF mRNA abundance, which was restored by the readdition of FBS (10%) within 2 h. The effect of FBS was completely abolished by protein kinase inhibitor H-7 (10 microM), suggesting that FBS-stimulated VEGF mRNA induction involves activation of protein kinases. The treatment of GEN with 10(-7) M 12-O-tetradecanoylphorbol-13-acetate (TPA) increased the VEGF mRNA abundance fivefold, supporting the idea that VEGF expression is regulated by protein kinase C. [3H]thymidine incorporation into GEN treated with TPA (10(-7) M) was inhibited by neutralizing antibody for VEGF. Thus VEGF was identified as an autocrine growth factor for GEN in vitro. Its physiological role might be the regulation of GEN proliferation, and the induction of VEGF expression by FBS and TPA suggests its involvement in the response of glomerular capillary endothelial cells to injury in certain pathophysiological states.

Animals↗
PubMed1994

[Partial purification and properties of deoxyribonucleases from eggs and liver of Xenopus laevis. Comparison with deoxyribonuclease II from bovine spleen].

Deoxyribonucleases from eggs and the liver of Xenopus laevis were partially purified by DEAE-cellulose and heparin-Sepharose affinity column chromatographies. The fractions having egg and liver DNase activities were eluted on high performance liquid chromatography through TSK gel G3000SW at the molecular weights of 41.5 and 45 kDa, respectively. The frog DNases hydrolyzed a native DNA over a heat-denatured DNA, and also formed double-strand cuts not only in linear lambda-DNA but also in closed circular pBR322DNA. The pH optimum of the DNases was 4.5-5.0 in 50 mM acetate buffer. These enzyme activities were abolished by treatment at 80 degrees C for 5 min and pH 2, 3 or 12 for 1 h. The enzymes act in such a manner as deoxyribonuclease II (from bovine spleen)-type nuclease with respect to substrate specificity, optimum pH and cation dependence.

Animals↗
PubMed1994

WF11899A, B and C, novel antifungal lipopeptides. II. Biological properties.

WF11899A, B and C, novel water-soluble lipopeptides related to the echinocandins, possess potent anti-Candida activities. The IC50s of the compounds against four clinical isolates of Candida albicans ranged from 0.004 to 0.03 microgram/ml by microbroth dilution assay. These compounds mildly suppressed the growth of Aspergillus fumigatus and A. niger. WF11899A, B and C showed a potent in vivo anti-Candida activity. Particularly, WF11899A was superior to cilofungin, and equal to fluconazole. 1,3-beta-glucan synthase was inhibited by these compounds at the IC50s of 0.7, 0.7 and 1.8 micrograms/ml for WF11899A, B and C, respectively. However, they hemolysed mouse red blood cells in vitro at the concentration of 62 micrograms/ml.

Animals↗