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H Ohshima

Publications and source records attributed to H Ohshima.

At least 181 records · Page 10Linked to original sources
PubMed1993

Further studies of the self-induced translation model of myosin head motion along the actin filament.

We have extended and refined the model of myosin head motion along the actin filament which we proposed in 1988 (J. Muscle Res. Cell Motility 9, 248-260), and obtained the following results. (1) We assumed that the height of the induced potential depends upon tension with a maximum around the isometric tension, and got a force-velocity relation similar to the observation by Oiwa et al. (1990) that the velocity of the myosin-coated beads along the actin cables decreases with increasing centrifugal force applied in the direction of bead movement and then the velocity tends to increase when the force increases in the same direction beyond a certain value. (2) We introduced a correction factor in the relation between the measured tension and the microscopic tension produced by myosin head, and got a feature in force-velocity relation similar to the observation by Edman (1988) that the velocity drops sharply as the tension approaches to about 80% of the isometric tension. (3) We assumed that binding of an ATP-activated myosin head to an actin filament causes a local structural change extended roughly 20nm long along the filament, which provides a potential well spread over about 16nm for the myosin head, with three shallow potential wells in it. We studied kinetics of the myosin head in the potential well of about 16nm in order to explain the early tension recovery after the sudden change of muscle length observed by Ford, Huxley and Simmons (1977), with results in good agreement with their experimental data.

Actin Cytoskeleton↗
PubMed1993

Inhibition of nitrosation.

Humans are exposed through ingestion or inhalation to preformed N-nitroso compounds (NOC) in the environment and through the endogenous nitrosation of amino precursors in the body. Activated macrophages and bacterial strains isolated from human infections can enzymatically produce nitrosating agents and NOC from precursors at neutral pH. As a consequence, endogenous nitrosation may occur at various sites of the body, such as the oral cavity, stomach, urinary bladder, and at other sites of infection or inflammation. Numerous substances to which humans are exposed have been identified and shown to inhibit formation of NOC. Such inhibitors include vitamins C and E, certain phenolic compounds, and complex mixtures such as fruit and vegetable juices or other plant extracts. Nitrosation inhibitors normally destroy the nitrosating agents and, thus, act as competitors for the amino compound that serves as substrate for the nitrosating species. Independently, epidemiological studies have already established that fresh fruits and vegetables that are sources of vitamin C, other vitamins, and polyphenols have a protective effect against cancers at various sites and in particular gastric cancer. This article briefly reviews (a) the chemistry of NOC formation and inhibition; (b) the studies in experimental animals that showed that inhibition of endogenous NOC synthesis leads to a reduction of toxic, mutagenic, and carcinogenic effects; (c) recent studies in humans where the degree of inhibition of endogenous NOC synthesis was directly quantified; and (d) the possible contribution of nitrosation inhibitors to human cancer prevention.

Animals↗
PubMed1993

Abdominal wall fat index, estimated by ultrasonography, for assessment of the ratio of visceral fat to subcutaneous fat in the abdomen.

PURPOSE: To establish a new index of regional fat distribution using ultrasonography for assessment of the ratio of the visceral fat area (V) to the subcutaneous fat area (S) (V/S ratio). SUBJECTS AND METHODS: The subjects examined were 62 patients (23 males and 39 females); 51 patients had hyperlipidemia and 11 patients had glucose intolerance. The mean body mass indices ranged from 20.3 to 42.9. The mean age of the patients was 44 +/- 13 years. The thicknesses of the preperitoneal fat layer (P) and subcutaneous fat layer (S) in the abdomen were measured by ultrasonography and the P/S ratio was calculated. The V/S ratio was obtained with radiographic computed tomography. RESULTS: Of the various P/S ratios examined, the ratio of the maximum thickness of preperitoneal fat to the minimum thickness of subcutaneous fat was most closely correlated with the V/S ratio (r = 0.746, p < 0.0001). This ratio was termed the abdominal wall fat index (AFI). AFI was positively correlated with serum triglyceride levels and negatively correlated with high-density lipoprotein cholesterol (r = -0.312, p < 0.05), whereas the V/S ratio was correlated with triglyceride levels. AFI was positively correlated with basal insulin levels in both men and women. CONCLUSION: These results suggest that AFI measured by ultrasonography may be a new indicator of visceral fat deposition, and may reflect metabolic disorders such as lipid metabolism and glucose metabolism disorders.

Abdominal Muscles↗
PubMed1993

Measurements and analyses of electrophoretic mobilities of RAW117 lymphosarcoma cells and their variant cells.

The electrophoretic mobilities of the cells of malignant lymphosarcoma cell line RAW117-P and its variant H10 with a highly metastatic property to the liver have been measured at various ionic strengths. The cells of parental cell line (RAW117-P) show higher mobility values in magnitude than those of its variant line (RAW117-H10) in the whole range of electrolyte concentration measured. We have also measured the sialic acid amount carried by cells of both lines. The content of sialic acids in RAW117-H10 cells is observed to be about 27% less than that in RAW117-P cells. The mobility data obtained have been analyzed by a novel mobility formula for colloidal particles with ion-penetrable surface charge layers. The observed mobility difference between RAW117-P cells and RAW117-H10 cells is found to be due to the difference in friction exerted by the cell surface layers on the liquid flow around the cells between these two types of cells and to the difference in fixed-charge density in their surface layers, which is caused by the 27% decrease in sialic acid content. A possible explanation for this mobility difference between these two types of cells is given.

Animals↗
PubMed1993

Electrophoretic mobility of a "soft particle" with a nonuniformly charged surface layer as a model for cells.

The electrophoretic mobility of a colloidal particle with a nonuniformly charged ion-penetrable surface layer in an electrolyte solution (as a model for a biological cell) is calculated for the case in which the surface charge layer consists of two oppositely charged sublayers. It is shown that the mobility and the surface potential (the latter of which is defined as the potential at the front surface of the surface charge layer) generally exhibit different behaviors, in contrast to the case of rigid particles, which is described by Smoluchowski's mobility formula. The mobility in some cases shows a minimum (or a maximum) when plotted as a function of the electrolyte concentration and alters its sign at a certain concentration, which is considered to be an isoelectric point of the mobility with respect to the electrolyte concentration. This isoelectric point is in general different from that of the surface potential.

Cell Membrane↗
PubMed1993

Increased endogenous N-nitrosamine and nitrate formation by induction of nitric oxide synthase in rats with acute hepatic injury caused by Propionibacterium acnes and lipopolysaccharide administration.

In rats treated i.v. with heat-killed Propionibacterium acnes (100 mg/kg body wt), followed 5 days later by an i.v. dose of Escherichia coli lipopolysaccharide (LPS, 1 mg/kg body wt), acute hepatic cell necrosis was accompanied by significant induction of nitric oxide (NO) synthase activity in the liver. Endogenous nitrosation of thiazolidine 4-carboxylic acid (TCA, 50 mumol/rat) administered by three different routes (i.v., i.p. and p.o.) 5 h after LPS injection to the P. acnes-treated rats was assessed by analysing its nitrosated product (NTCA) excreted in 24 h urine. The amounts of NTCA formed in vivo after i.v., i.p. and p.o. administration of TCA were 4.07 +/- 1.00, 5.79 +/- 2.15 and 58.3 +/- 20.7 nmol/rat (n = 5-10) respectively, which were about 5-, 10- and 8-fold greater than those excreted by rats which had not been treated with P.acnes and LPS but received TCA by the same route. Nitrate concentration in plasma and NO synthase activity in the liver started to increase within 2.5 h after LPS injection, reached a maximum at 7.5 h and remained at high levels for several further hours. Levels of nitrite and nitrate in gastric contents were also increased significantly after LPS administration. The co-administration of N omega-nitro-L-arginine (an inhibitor of NO synthase) and LPS resulted in a marked reduction of urinary levels of nitrate and NTCA, indicating that nitrosation is mediated by NO synthase. These results together suggest that induction of NO synthase by infection with bacteria, parasite and viruses could result in increased endogenous nitrosation not only in the infected tissues but also in the stomach, where nitrosamines would be formed more rapidly under acidic conditions.

Amino Acid Oxidoreductases↗
PubMed1993

Morphologic variation of lumbar posterior longitudinal ligament and the modality of disc herniation.

The authors investigated the relationship between the type of lumbar disc herniation (471 discs) and the gross anatomy of the posterior longitudinal ligament (PLL) in the lumbar region of 10 cadavers. The size of PLL diminished significantly as the disc level became lower (P < 0.00001), and there are loose attachment of the central area of rhomboidal expansion of PLL. In the upper lumbar region, central or central-lateral herniation with an intact PLL was predominant. The type of disc herniation appeared to be influenced by the width and development of the PLL with a loosely connected central area. In the lower lumbar region, posterior-lateral extrusion with a ruptured PLL was predominant. This may be related to the small or poorly developed PLL in lower lumbar/lumbosacral region. It is suggested that the type of disc herniation (PLL intact or ruptured) is related to the morphologic variation of PLL.

Aged↗
PubMed1993

Stable positively charged liposome during long-term storage.

The effect of taurine, as an isotonic solute, and of benzalkonium chloride (BZC), as a positive membrane component, on the long-term stability of liposomal suspensions was investigated by measuring surface potential. The surface potential, which introduced electrostatic repulsion to liposomes against aggregation, increased dose-dependently with the addition of BZC, which gave a positive charge. However, a further addition of BZC caused unexpected aggregation during storage, so the optimum addition of BZC was defined. On the other hand, taurine, which forms a zwitter ion in an aqueous solution, did not reduce the surface potential, suggesting that taurine is of possible utility as an isotonic solute. As the result of stability testing, the liposomal system using taurine and BZC was stable against aggregation during 6 months at 40 degrees C. We were successful in developing a stable, positively charged liposomal system during long-term storage, and our liposomal system is believed to be of wide utility as a drug carrier for therapeutic drugs applied topically to negatively charged mucosal tissues. We applied the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to estimate the colloidal stability of liposomes. As a result of stability testing, positively charged liposomes had a good correlation between maximum total repulsive energy (VT(max)/kT) between two liposome particles and colloidal stability, suggesting that the VT(max)/kT value is useful for estimating stability and for designing liposomal preparations containing some ionic substances.

Benzalkonium Compounds↗
PubMed1993

Urinary markers for measuring exposure to endogenous and exogenous alkylating agents and precursors.

Noninvasive methodologies for measuring carcinogen exposure in humans, based on the use of urinary markers, are being developed and validated for use in molecular epidemiological studies. A range of 3-alkyladenines can be determined in urine samples by an immunoaffinity purification-GC/MS approach [3-methyladenine, 3-ethyladenine, 3-(2-hydroxyethyl)adenine, and 3-benzyladenine]. Using this method, recent results in human subjects suggest that urinary 3-alkyladenines are potentially useful markers of alkylating agent exposure, particularly where the backgrounds of such adducts are much lower than 3-methyladenine. Urinary excretion of S-benzylmercapturic acid has been studied in experimental animals as a marker of exposure to benzylating agents such as N-nitroso-methylbenzylamine. 3-Nitrotyrosine (NTyr) is formed in vivo in tissue or blood proteins after exposure to nitrosating and/or nitrating agents such as tetranitromethane. After turnover of proteins, NTyr is released and excreted in urine as metabolites 3-nitro-4-hydroxy-phenylacetic acid and 3-nitro-4-hydroxyphenylacetic acid, which are determined by GC with a thermal energy analyzer. The sensitivity and specificity, combined with ease of use, of these noninvasive biomonitoring approaches means that they may be readily incorporated into molecular epidemiological studies in which exposure to nitrosating and alkylating agents may be important risk factors.

Acetylcysteine↗
PubMed1993

Late cardiac strangulation due to an iatrogenic pericardial defect.

A 14-year-old boy developed broad posterolateral myocardial infarction. During cardiac surgery at age five, a small pericardial window had been made. Autopsy revealed an extensive left-sided pericardial defect and necrosis of the left ventricular free wall, which had herniated and strangulated through the enlarged pericardial defect.

Adolescent↗
PubMed1993

Histochemical localization and X-ray microanalysis of calcium in the rat submandibular gland: demonstration of possible sites for microlith induction.

Rapidly frozen and freeze-substituted submandibular glands of young female rats were embedded in Epon and processed for histochemical demonstration of calcium with the glyoxal bis (2-hydroxyanil) (GBHA) staining method. GBHA staining of thick Epon sections revealed discrete calcium reactions of moderate intensity in practically every secretory granule but not in other compartments of the acinar cells. The saliva in the excretory duct was also reactive with GBHA and showed a drastic decrease in staining intensity toward the distal segments of excretory ducts with larger diameters. In addition, the duct saliva contained numerous tiny particles that were highly GBHA reactive. Stromal cells and cells lining the excretory duct were totally free of reactions. In the acinar cells, X-ray analysis detected distinct peaks for calcium in secretory granules and smaller ones in the Golgi apparatus, while they were undetectable in the rough surfaced endoplasmic reticulum (RER), implicating post-RER calcium loading in the secretory pathway. Electron-dense deposits in the duct saliva showed distinct peaks both for calcium and phosphorus, though these appeared in the acinar secretory granules and other cytoplasmic regions lacked phosphorus. Our observations thus demonstrated physiological calcium in the intra- as well as extracellular compartments of the submandibular gland, and further confirmed drastic changes in chemical composition along the synthetic and secretory pathways of the saliva, by both histochemical and X-ray microanalytical methods. GBHA staining of calcium combined with X-ray microanalysis is useful for an evaluation of the physiology and histo-pathological changes of the salivary glands associated with initial phases of microliths as well as sialoliths formation.

Aminophenols↗
PubMed1993

The 'midband' lipoprotein is a coronary risk factor in Japanese patients with familial hypercholesterolaemia.

The relationship between coronary stenosis and 'midband' lipoprotein, which was observed between low density lipoproteins and very low density lipoproteins by 3% polyacrylamide gel electrophoresis, was studied in patients with heterozygous familial hypercholesterolaemia (FH). The subjects were 46 patients with FH, who were evaluated by coronary angiography. The groups with and without coronary artery disease (CAD) were compared. Age, sex ratio, total cholesterol, triglyceride, HDL-cholesterol and lipoprotein(a) levels were matched in these two groups. In addition, Achilles tendon thickness and the incidence of risk factors such as diabetes mellitus, hypertension and smoking between these two groups were matched. Under these conditions, the frequency of midband was higher in the patients with CAD (20/26) than that in patients without (4/20). The results suggest that the presence of a midband among Japanese is an independent risk factor for coronary stenosis even in cases of FH who have severe hypercholesterolaemia.

Adult↗
PubMed1993

[Subtypes of alpha 1-adrenoceptors in urinary bladder and urethral smooth muscle and prostatic adenoma].

Two alpha 1-adrenoceptor subtypes (alpha 1A and alpha 1B) have been distinguished by competitive antagonists and alkylating agent chloroethylclonidine (CEC). The CEC-insensitive subtype (alpha 1A) had been suggested to selectively activate Ca2+ influx through Ca-channels in smooth muscle cell membrane. We examined the effects of WBC4101, CEC and verapamil on contractile responses to phenylephrine in rabbit aorta, urinary bladder and urethral smooth muscle and in human prostatic adenoma to examine the alpha 1-adrenoceptor subtypes in these tissue. Pretreatment with WB4101 caused a large shift to the right for phenylephrine-induced dose response curves and verapamil decreased the phenylephrine-induced contractions of rabbit aorta, urinary bladder and urethral smooth muscles and human prostatic adenomas. CEC inhibited only phenylephrine induced contractions of human prostatic adenomas. The pA2 value for WB4101 was significantly lower in human prostate than in rabbit aorta, urinary bladder and urethra. These results suggest that functional alpha 1-adrenoceptor subtypes involve alpha 1A and alpha 1B in human prostatic adenoma, while only alpha 1A in rabbit aorta, urinary bladder and urethral smooth muscles.

Aged↗
PubMed1993

Immunohistochemical localization of an inducible form of nitric oxide synthase in various organs of rats treated with Propionibacterium acnes and lipopolysaccharide.

Immunohistochemical localization of an endotoxin-inducible form of nitric oxide synthase was examined using rabbit polyclonal antibody against the enzyme purified from rat liver. In rats treated with Propionibacterium acnes and lipopolysaccharide, immunostaining was observed in macrophages, occasional lymphocytes, neutrophils and eosinophils in red pulp of spleen, Kupffer cells, endothelial cells and hepatocytes in liver, alveolar macrophages in lung, macrophages and endothelial cells in adrenal glands, and histiocytes, eosinophils, mast cells and endothelial cells in colon. Immunoreactivity was also evident in the following tissues: histiocytes and endothelial cells in kidney; histiocytes and neutrophils in esophagus; macrophages and eosinophils in duodenum; macrophages, some lymphocytes and mast cells in ileum; histiocytes in thymus; and endothelial cells in heart and aorta. Immunoreactivity was not detected in these organs from untreated rats. Positively staining cells in these rat organs appeared within 2.5 h after lipopolysaccharide administration; their number dramatically increased within the next 2.5 h, remained at high levels for a further 19 h, and then decreased over the following 24 h. The number of positive cells appearing correlated well with the nitric oxide synthase activity biochemically determined in the same organs.

Adrenal Glands↗
PubMed1993

[Effect of physical exercise training on graft patency after aortocoronary bypass grafting].

This study evaluated the effect of physical exercise training on graft patency after aortocoronary bypass grafting (ACBG). Patients who underwent ACBG were randomized into the training (17 patients, 43 grafts) and nontraining groups (18 patients, 45 grafts). Tissue plasminogen activator (TPA) antigen, TPA activity, plasminogen activator inhibitor-1 (PAI-1) antigen and PAI-1 activity as fibrinolysis variables, and an angiographic study were performed 2 and 26 weeks after ACBG. Plasma TPA activity increased significantly in the training group, but not in the nontraining group after 24 weeks of training. Plasma PAI-1 antigen and activity decreased significantly in the training group, while PAI-1 levels remained unchanged in the nontraining group. Grafts were patent in 93% (40 of 43) of the training group and 76% (34 of 45) of the nontraining group (p < 0.05). A high plasma concentration of PAI-1 may interfere with the natural thrombolytic process. Exercise training can decrease PAI-1 levels and increase TPA activity after ACBG. Improved fibrinolysis obtained by exercise training may have beneficial effects on graft patency.

Adult↗
PubMed1993

Structural variation of the anterior and posterior anulus fibrosus in the development of human lumbar intervertebral disc. A risk factor for intervertebral disc rupture.

A morphologic comparison of the laminated structure of the anterior and posterior anulus fibrosus of lumbar intervertebral disc was made on 24 L3-4 and L4-5 discs obtained from 10 fetus, one child, and one young adult cadavers. Low power microscopic and polarized microscopic observations and measurements on the transverse sections were performed to assess 1) lamellar bundle arrangement, 2) number of distinct lamellar bundles, 3) percentage of incomplete lamellar bundles, and 4) fiber-interlacing angles. The number of lamellar bundles was greater in the anterior anulus than in the posterior anulus. A very complex structure was observed in the posterior middle anulus in all the specimens, with a high percentage of incomplete/discontinuous lamellar bundles and greater fiber-interlacing angles. Loose connection of the lamellar bundles of posterior outer anulus was observed in fetal discs. The annular strength was not measured in the present study, however, the risk of posterior disc rupture in the young may be influenced by an inherent structural variation with a weak posterior anulus fibrosus.

Adult↗
PubMed1992

Identification of inducible calmodulin-dependent nitric oxide synthase in the liver of rats.

A calmodulin-dependent nitric oxide synthase was significantly induced in the liver of rats treated intravenously with heat-killed Propionibacterium acnes and 5 days later with Escherichia coli lipopolysaccharide. The apparent calmodulin-dependent and -independent isozymes were separated by Mono Q column chromatography after their partial purification by 2',5'-ADP-agarose affinity chromatography. Both enzymes had a molecular weight of 125,000 as determined by SDS-polyacrylamide gel electrophoresis and required NADPH, tetrahydrobiopterin, and dithiothreitol as cofactors. Their activities were completely inhibited by the specific nitric oxide synthase inhibitors NG-monomethyl-L-arginine and N omega-nitro-L-arginine at 80 and 800 microM, respectively. The peptide maps of these two isozymes with lysylendopeptidase and their reverse-phase column chromatographic profiles were indistinguishable. In the presence of bovine calmodulin, the purified calmodulin-dependent isozyme behaved as a calmodulin-independent isozyme on Mono Q column chromatography. The purified calmodulin-independent isozyme was converted to a calmodulin-dependent isozyme by EDTA and EGTA. Calmodulin blot analysis using 125I-calmodulin showed that the two isozymes bound calmodulin equally efficiently.

Amino Acid Oxidoreductases↗