Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 523 records · Page 29Linked to original sources

PubMed1998

Reactive oxygen species in reoxygenation injury of rat brain capillary endothelial cells.

OBJECTIVE: To clarify the mechanism of anoxia/reoxygenation (A/R) injury of rat brain capillary endothelial cells (BCEC). METHODS: BCEC isolated from Sprague-Dawley rats by enzymatic treatment and centrifugation were subjected to anoxia (95% N2, 5% CO2) for 20 minutes and then to reoxygenation (95% air, 5% CO2) for 3 hours. Enzyme inhibitors, including oxypurinol, indomethacin, and N(G)-nitro-L-arginine methyl ester, or specific free-radical scavengers, such as superoxide dismutase, catalase, and the ferric iron chelator deferoxamine, were added before A/R injury. The BCEC were incubated in a range of Ca2+ concentrations from 1 to 0.01 mmol/L during A/R injury. Cytotoxicity was assayed by release of intracellular lactate dehydrogenase (LDH). RESULTS: With A/R injury, LDH release from the control group (no protective agents) significantly increased (44.8 +/- 3.3%), compared with a small increase in a normoxic group. BCEC treated with oxypurinol, indomethacin, or N(G)-nitro-L-arginine methyl ester showed suppression of LDH release. LDH release was almost totally suppressed by superoxide dismutase and partially by catalase or deferoxamine. The LDH release was partly dependent on calcium concentration. CONCLUSION: BCEC subjected to A/R become potent generators of free radicals, especially superoxide anion. Free radical production depends on both xanthine oxidase and cyclooxygenase pathways. Peroxynitrite and extracellular Ca2+ both contribute importantly to reoxygenation injury of BCEC.

Animals↗

PubMed1998

Environmentally controlled dimorphic cycle in a fission yeast.

The fission yeast Schizosaccharomyces pombe shows bipolar growth and is a convenient model for studying cell polarity and polar growth. This paper shows that the related Schiz. japonicus var. japonicus can switch to unipolar growth and can exist in both yeast and mycelial phases. On solid media, the yeast phase is unstable and prone to switch to the mycelial form, which shows unipolar growth by tip elongation. The hyphae can colonize the body of the substrate (true mycelium) or just its surface (pseudo-mycelium). The yeast-to-mycelium transition and the growth of the mycelium are regulated by a nutritional gradient and are associated with extensive vacuolation. The mycelium can convert into arthroconidia or return to the yeast phase in response to environmental changes. These environmentally controlled morphological transitions make Schiz. japonicus var. japonicus an attractive model for the investigation of cell polarity and morphogenesis.

Cell Polarity↗

PubMed1998

Fine structural and histochemical study of equine Paneth cells.

Ultrastructure, lysozyme and glycoconjugate activity in duodenal Paneth cells were observed concurrently in the horse. Paneth cells were seen to uniformly line the base of the equine intestinal glands. The round secretory granules have centrally located electron densities with peripherally located electron lucent halos. Histochemically, the peripheral halo layer was positively stained for carbohydrates by the periodic acid-thiocarbohydrazide-silver protein-physical development (PA-TCH-SP-PD) method and the entire granules reacted positively to the WGA. The central core area reacted with anti-lysozyme. We identified a young (Type I) and an old (Type II) cell population in the same crypt, but we suggest that the observed populations are variations of the same cell type with the varied appearance due to aging of the secretory granules.

Animals↗

PubMed1998

Augmented exercise plasma noradrenaline with impaired chronotropic responsiveness in patients with hypertrophic cardiomyopathy.

1. There is controversy regarding plasma catecholamine levels in patients with hypertrophic cardiomyopathy (HCM) and few data exist on serial plasma catecholamine measurements during exercise. The present study determined whether cardiovascular and plasma catecholamine responses to exercise were altered in patients with HCM. 2. Plasma noradrenaline (NA) and adrenaline were measured at rest, at the end of each stage during exercise and immediately and 5 min after submaximal treadmill exercise in 15 patients with non-obstructive HCM (13 males, two females; mean (+/- SEM) age 54 +/- 3 years) and in 15 age- and sex-matched controls. The ratio of the increment in heart rate (HR) divided by the increment in plasma NA during exercise (delta HR/delta NA) was used as an index of chronotropic sympathetic responsiveness to exercise. 3. Exercise duration was shorter (11.2 +/- 0.6 vs 8.7 +/- 0.6 min for control vs HCM, respectively; P < 0.01) and diastolic blood pressure was significantly higher at stages I and II of modified Bruce protocol HCM. 4. Resting plasma NA levels (149 +/- 17 vs 167 +/- 28 pg/mL for control vs HCM, respectively; NS) were not different, but plasma NA levels at stages I and II were significantly higher in HCM than in controls (243 +/- 26 vs 399 +/- 69 pg/mL (P < 0.05) and 308 +/- 30 vs 548 +/- 110 pg/mL (P < 0.05), respectively). 5. Peak plasma NA levels were not significantly higher in HCM than in controls (578 +/- 59 vs 918 +/- 184 pg/mL, respectively; NS). 6. The ratio delta HR/delta NA was significantly lower in HCM compared with control at stages I and II (0.49 +/- 0.10 vs 0.21 +/- 0.05 (P < 0.05) and 0.38 +/- 0.06 vs 0.20 +/- 0.05 (P < 0.05), respectively). There were no differences in plasma adrenaline responses during exercise between the two groups. 7. Patients with HCM had augmented plasma NA levels during submaximal exercise with a higher diastolic blood pressure response. Chronotropic sympathetic responsiveness was impaired during the early stages of exercise in patients with HCM.

Adult↗

PubMed1998

Case report: Insulin-like growth factor II expression in hepatocellular carcinoma with alcoholic liver fibrosis accompanied by hypoglycaemia.

This case of hepatocellular carcinoma (HCC) with alcoholic liver fibrosis, which was not associated with hepatitis viruses, was accompanied by hypoglycaemia. The immunoreactive insulin level was low and other hormonal examinations were almost normal. Immunohistochemical studies showed a high level of insulin-like growth factor II (IGF2) peptide in the HCC section and the size heterogeneity of serum IGF2 investigated by western blot revealed a large form at approximately 15 kDa. These results suggest that the HCC with alcoholic liver fibrosis produced IGF2 and that the hypoglycaemia was caused by tumour-associated IGF2.

Carcinoma, Hepatocellular↗

PubMed1998

Cavernous haemangioma in the coronary sinus.

A 58 year old man with a history of cerebral infarction was admitted to hospital with chest discomfort and dyspnoea. He had no history of precordial chest discomfort. Angiography and left ventriculography showed that coronary fistulas connected the coronary sinus with the left circumflex and right coronary arteries. His coronary sinus did not communicate with the right atrium, draining instead into a persistent left superior vena cava. Angiography showed a mass, suspected to be a thrombus, in the coronary sinus. Transoesophageal echocardiography confirmed the presence of a mass in the atrioventricular groove. The mass was removed at surgery and proved to be a cavernous haemangioma.

Coronary Angiography↗

PubMed1998

Sulfhydryls associated with H2O2-induced channel activation are on luminal side of ryanodine receptors.

The mechanism underlying H2O2-induced activation of frog skeletal muscle ryanodine receptors was studied using skinned fibers and by measuring single Ca(2+)-release channel current. Exposure of skinned fibers to 3-10 mM H2O2 elicited spontaneous contractures. H2O2 at 1 mM potentiated caffeine contracture. When the Ca(2+)-release channels were incorporated into lipid bilayers, open probability (Po) and open time constants were increased on intraluminal addition of H2O2 in the presence of cis catalase, but unitary conductance and reversal potential were not affected. Exposure to cis H2O2 at 1.5 mM failed to activate the channel in the presence of trans catalase. Application of 1.5 mM H2O2 to the trans side of a channel that had been oxidized by cis p-chloromercuriphenylsulfonic acid (pCMPS; 50 microM) still led to an increase in Po, comparable to that elicited by trans 1.5 mM H2O2 without pCMPS. Addition of cis pCMPS to channels that had been treated with or without trans H2O2 rapidly resulted in high Po followed by closure of the channel. These results suggest that oxidation of luminal sulfhydryls in the Ca(2+)-release channel may contribute to H2O2-induced channel activation and muscle contracture.

4-Chloromercuribenzenesulfonate↗

PubMed1998

Augmentation of mitochondrial reduced glutathione by S-adenosyl-L-methionine administration in ischemia-reperfusion injury of the rat steatotic liver induced by choline-methionine-deficient diet.

We examined whether warm ischemia-reperfusion (I/R) damage of the rat steatotic liver can be reduced by administration of S-adenosyl-L-methionine (SAMe). We examined the effect of SAMe on the mitochondrial reduced-glutathione (GSH) pool. Sixty minutes of partial left lobar vascular clamping followed by 2 h of reperfusion were employed for a model of hepatic warm ischemia. Either 5% dextrose or SAMe was injected intraperitoneally 2 h before I/R in steatotic rats (S-D5% or S-SAMe group). Serum liver enzyme concentrations 2 h after reperfusion were significantly lower in the S-SAMe group than in the S-D5% group. The cytosolic and mitochondrial GSH concentrations after I/R were significantly higher in the S-SAMe group than in the S-D5% group (p < 0.05). The cytosolic and mitochondrial oxidized-glutathione/GSH ratios after I/R were significantly greater in the S-D5% group than in the S-SAMe group (p < 0.01). The adenosine triphosphate concentration was higher in the S-SAMe group than in the S-D5% group (p = 0.0515). These results show that hepatocellular and mitochondrial oxidative stress after I/R in the steatotic liver can be reduced by administration of SAMe. The results also show that mitochondrial function and hepatocellular integrity can be restored by administration of SAMe in steatotic rats.

Animals↗

PubMed1998

Immunohistochemical localization of apolipoprotein B-100 (ApoB-100) and expression of glutathione peroxidase (GSH-PO) in canine atherosclerotic lesions.

We used immunohistochemistry to localize canine Apolipoprotein B-100 (CApoB-100) and glutathione peroxidase (GSH-PO) in canine atherosclerotic lesions. CApoB-100 was deposited in the tunica intima and cytoplasms of infiltrating macrophages in early atherosclerotic lesions. In advanced atherosclerotic lesions, the cystic space of the lesions contained a large amount of CApoB-100 immunoreactive material. Expression of GSH-PO was recognized in the foamy cytoplasm of macrophages and smooth muscle cells in the early and advanced atherosclerotic lesions. These results indicate that expression of GSH-PO is closely associated with the deposition of CApoB-100. In addition, they suggest that, as in human atheromas, low-density lipoprotein (LDL) is peroxidized and changed into modified LDL. Deposition of modified LDL (oxidized or acetylated) may be a critical step in the formation of canine atherosclerotic lesions.

Animals↗

PubMed1998

Inhibitory effect of zinc and copper on phosphatase activity in the brain cytosol of rats: involvement of SH groups.

The effect of various metal ions on neutral phosphatase activity in the brain cytosol of rats was investigated. p-Nitrophenylphosphate was used as the substrate for the enzyme assay. Brain cytosolic phosphatase activity was significantly decreased by the presence of zinc or copper in the range of 10(-5) to 10(-3) M in the enzyme reaction mixture, while it was significantly increased by manganese, nickel or cobalt (10(-5) to 10(-3) M). Calcium (10(-5) to 10(-3) M) did not have an appreciable effect on brain cytosolic phosphatase activity. The inhibitory effect of zinc (10(-5) M) or copper (10(-5) M) on phosphatase activity was seen in the presence of manganese, nickel or cobalt with 10(-4) M concentration, indicating a potent inhibitory effect of these metals. Zinc or copper-decreased phosphatase activity was clearly prevented by dithiothreitol (5 mM), although the effect of each metal was further enhanced by N-ethylmaleimide (5 mM), suggesting that the metals act on the SH-groups of enzyme. Moreover, the inhibitory effect of zinc (10(-5) M) was significantly enhanced by S-100A (10(-6) M) or calbindin (10(-7) M), although neither protein had any effect in the presence of calcium (10(-5) M) or copper (10(-5) M). These results suggests that zinc has an unique role in the regulation of neutral phosphatase activity in rat brain cytosol.

Animals↗

PubMed1998

Inhibitory effect of calcium-binding protein regucalcin on protein kinase C activity in rat renal cortex cytosol.

The effect of regucalcin, a calcium-binding protein, on Ca2+-and phospholipid-dependent protein kinase (protein kinase C) activity in the cytosol of rat kidney cortex was investigated. With increasing concentrations of Ca2+, phosphatidylserine or dioctanoylglycerol in the reaction mixture, regucalcin (10[-8] M) caused a remarkable inhibition of protein kinase C activity. Regucalcin did not have a significant effect on protein kinase C activity in the presence of phosphatidylserine or dioctanoylglycerol without Ca2+ addition. Moreover, regucalcin significantly inhibited phorbol 12-myristate 13-acetate (PMA)-increased protein kinase C activity. Meanwhile, staurosporine (10[-9] M) caused a significant inhibition of protein kinase C activity. This inhibition was further enhanced by regucalcin addition. Regucalcin itself did not have protein kinase activity in either the presence or the absence of both Ca2+ and phospholipids. These results clearly indicate that regucalcin has an inhibitory effect on protein kinase C activity in the cytosol of rat kidney cortex. This inhibitory effect may be partly due to the regucalcin-induced Ca2+ binding.

Animals↗

PubMed1998

Sexual difference of hepatic calcium-binding protein regucalcin mRNA expression in rats with different ages: effect of ovarian hormone.

The sexual difference of calcium-binding protein regucalcin mRNA expression in the liver of rats was investigated by Northern blot analysis. Liver regucalcin cDNA (0.9 kb of open reading frame) was used as a probe. The analysis of total RNAs extracted from various tissues of rats indicated that regucalcin mRNA was present primarily in the liver with a size of 1.8 kb. Hepatic regucalcin mRNA was expressed in male rats more than in females. This sexual difference was also seen in aged rats (50 weeks old), although the expression was decreased with increasing age. Ovariectomy did not cause a significant alteration in hepatic regucalcin mRNA levels. The subcutaneous administration of 17beta-estradiol (0.2 mg/100 g body weight) in ovariectomized rats did not cause an appreciable increase in hepatic mRNA levels. The results demonstrate that regucalcin mRNA expression in rat liver is based on sex, and that this difference may not be related to estrogen.

Aging↗

PubMed1998

Inhibitory effect of regucalcin on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol.

The effect of regucalcin, a Ca2+-binding protein, on Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex cytosol was investigated. The addition of Ca2+/calmodulin in the enzyme reaction mixture caused a significant increase in the dephosphorylation of p-nitrophenylphosphate and phosphotyrosine used as the substrate for phosphatase in rat renal cortex cytosol. The presence of regucalcin (10(-6) M) in the enzyme reaction mixture caused a complete inhibition of Ca2+/calmodulin-dependent phosphatase activity in renal cortex cytosol. A half maximum effect of regucalcin inhibition was seen at 10(-8) M concentration. Moreover, phosphatase activity of purified calcineurin was significantly enhanced by the addition of Ca2+/calmodulin. This enhancement was completely inhibited by the presence of regucalcin (10(-7) M). The inhibitory effect of regucalcin was not weakened by increasing concentrations of CaCl2 (10(-6) to 10(-4) M). The present results suggest that regucalcin can inhibit Ca2+/calmodulin-dependent phosphatase activity in rat renal cortex.

Animals↗

PubMed1998

Histoplasmosis in the skin and gingiva in a dog.

An 8-year-old, female mongrel dog had granulomatous lesions in the skull skin and gingiva of the left mandible. The lesions were macroscopically seen as grayish white papular granulomas, and microscopically consisted to numerous swollen macrophages and a few neutrophils without fibrocaseous necrosis. Macrophages contained many small oval or round-shaped yeast-like cells and a few rod-shaped organisms indicating a narrow based budding in their cytoplasm. The yeast-like cells were 2-5 microns (average 3.5 microns) in diameter, and appeared as a central, spherical, lightly basophilic body surrounded by a clear zone or "halo". The cell wall and central body were stained by the periodic acid-Shiff, Grocott's methenamine silver impregnation, or Gridley fungus method. Immunohistochemically, yeast-like cells were positive to anti-histoplasma yeast antibody, and rod-shaped organisms were positive to anti-histoplasma mycelial antibody. The present paper describes the first case of canine histoplasmosis in Japan.

Animals↗

PubMed1998

Effect of aging on functional changes of periodontal tissue cells.

Although the severity of periodontal disease is known to be affected by age, functional changes of periodontal tissue cells during the aging process are not well characterized. It is important to define how cellular aging affects the progression of periodontal diseases associated with the aging process. In vitro aging of human gingival fibroblast (HGF) and periodontal ligament fibroblast (HPLF) cells was prepared by sequential subcultivations (5 to 6 passages as young, 18 to 20 passages as old). GFs were also prepared from gingiva of Down's syndrome patients and 60-week-old rats. Fetal rat calvarial osteoblasts were prepared by sequential digestion with collagenase. HGF and HPLF cells were treated with lipopolysaccharide (LPS) and cyclic tension force, respectively. Amounts of PGE2, interleukin (IL)-1 beta, IL-6, and plasminogen activator (PA) in conditioned media were measured. Total RNA was extracted, and mRNA expression was analyzed by reverse transcription polymerase chain reaction (RT-PCR). LPS-stimulated PGE2, IL-1 beta, IL-6, and PA production was increased in "old" HGF compared to younger cells. According to RT-PCR analysis, gene expression of COX-2, IL-1 beta, IL-6, and tissue type (t) PA was higher in old cells than in young cells. Cyclic tension force to HPLF also stimulated phenotypic and gene expression of IL-1 beta, PGE2 (COX-2 gene) and tPA. These findings suggest that aging in both HGF and HPLF may be an important factor in the severity of periodontal disease through higher production of inflammatory mediators in response to both LPS and mechanical stress. In addition, oxygen radical-treated fibronectin (FN) as substratum diminished bone nodule formation by osteoblasts when compared with intact FN. This finding suggests that FN plays an important role in Osteoblast activity and that FN damaged by oxygen radicals during the aging process may be related to less bone formation.

Adolescent↗

PubMed1998

Induction of COX-2 expression by mechanical tension force in human periodontal ligament cells.

Occlusal trauma is caused by excessive occlusal forces and is associated with alveolar bone loss. In the periodontal ligament (PDL), which primarily receives the occlusal force, there is increased prostaglandin E (PGE2) synthesis in response to mechanical stress, and many studies have shown that PGE2 is involved in the pathogenesis of periodontal diseases. Recently, two isozymes of cyclooxygenase, COX-1 and COX-2, which are key enzymes in prostaglandin (PG) biosynthesis, were identified and COX-2 was induced following the activation of cells by a variety of proinflammatory agents. However, the biosynthetic pathway of mechanical stress-dependent PGE2 from PDL cells has not been well understood. When cyclic tension force was applied to human PDL cells (18% increase in surface area), PGE2 release to the culture medium increased in a time-dependent manner. As analyzed by semi-quantitative PCR, COX-2 mRNAs, while hardly detectable in controls, increased dramatically on day 3 and 5 in response to tension force. In contrast, COX-1 mRNAs detected in controls were not affected by tension force. By immunocytochemical staining, COX-2 protein was significantly increased by tension force around the unstained cell nucleus in a time-dependent manner. When NS-398, a selective COX-2 inhibitor, was added to the medium, PGE2 synthesis increased by tension force was completely inhibited. These results indicate that tension force induces COX-2 in human PDL cells and that this induction is responsible for the augmentation of PGE2 production stimulated by tension force. Since selective COX-2 inhibitors have less adverse effects compared with those of non-steroidal anti-inflammatory drugs, they may be of therapeutic benefit for treatment of periodontal disease accompanying traumatic occlusion.

Alveolar Bone Loss↗

PubMed1998

Trends of average intake of macronutrients in 47 prefectures of Japan from 1975 to 1994--possible factors that may bias the trend data.

To describe the geographical patterns and trends of macronutrient intake in Japan for the recent 20 years, we analyzed the data sets of the National Nutrition Surveys (J-NNS). First, we calculated regression coefficients for survey year by prefecture for energy, protein, fat, and carbohydrate intake. These results, however, could be affected by the changes in age and sex distributions of the survey samples. Secondly, as the food consumption data were based on household as a unit, we used proportions of the subjects who belong to age-specific groups and female subjects in a sub-sample for each prefecture in a given year for adjustment by general lineal model. As a result, 1% increase in the subjects aged 1-4, 10-19 and 65- years and female subjects was equivalent to the changes in average energy intake by -5.88, +2.27, -1.45 and -1.62 kcal, respectively. After the adjustment for age and sex, number of significant negative coefficients among 47 prefectures decreased for energy and carbohydrate intake, and that of positive coefficients increased for fat intake. This suggested that unadjusted trend data might lead to an overestimation of decreasing trends of energy and carbohydrate intake, and an underestimation of increasing trend of fat intake in the recent 20 years.

Adolescent↗

PubMed1998

Effects of liposome-encapsulated hemoglobin on phorbol ester-induced superoxide production and expression of costimulatory molecules by monocytes in vitro.

The effects of Neo Red Cell (NRC), a liposome-encapsulated hemoglobin (LEH), on the phorbol ester-induced superoxide production and the expression of costimulatory molecules by human peripheral monocytes were investigated. The treatment of human mononuclear cells with NRC caused the potentiation of superoxide production in response to PMA. The longer incubation (20 h) resulted in a decrease in the PMA-induced superoxide production, which was in parallel to a decrease in the viability of the monocytes. A flow cytometric analysis showed that a slight expression of CD80 (B7-1) on monocytes was induced by NRC treatment, whereas the constitutive expressions of CD86 (B7-2) and CD54 (ICAM-1) were unchanged. The activation of monocytes with interferon-gamma (IFN-gamma) induced the expressions of CD80, CD86, and CD54 under all conditions tested, but NRC treatment tended to decrease the IFN-gamma-induced expression of CD54 on monocytes. These results suggest that the administration of LEH may modify the functions of human monocytes.

Antigens, CD↗