Biomedical subjects

H Ohshima

Publications and source records attributed to H Ohshima.

At least 19 recordsLinked to original sources

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↗

PubMed1992

Polyclonal antibody against an inducible form of nitric oxide synthase purified from the liver of rats treated with Propionibacterium acnes and lipopolysaccharide.

A polyclonal antibody was raised in the rabbit against an inducible form of nitric oxide (NO) synthase (EC 1.14.23) purified from the liver of rats with acute liver necrosis induced by i.v. administration of Propionibacterium acnes and lipopolysaccharide. The antibody immunoprecipitated NO synthase activities in the soluble extract of the liver from treated rats. Western blot analysis showed that the cytosols of the liver, lung and spleen from the treated rats but not from non-treated rats, and that of murine macrophages cultured in the presence of lipopolysaccharide and interferon-gamma, contained immunoreactive protein with a molecular weight of 125 kDa. The antibody, however, does not cross-react with a 150 kDa constitutive form of NO synthase present in the brain of rats, indicating that the inducible and constitutive enzymes are immunologically distinguishable.

Amino Acid Oxidoreductases↗

PubMed1992

Purification of nitric oxide synthase from bovine brain: immunological characterization and tissue distribution.

Nitric oxide (NO) synthase (EC 1.14.23) was purified to homogeneity from bovine cerebrum. The molecular weight of NO synthase was estimated to be 150 kDa by both SDS/PAGE and gel filtration at high salt concentration. For activity, the enzyme required NADPH, Ca2+, calmodulin and tetrahydrobiopterin as cofactors. Rabbit polyclonal antibody to bovine brain NO synthase reacted with 150 kDa NO synthase in various bovine and rat organs, including the brain, pituitary and adrenal glands, but not with that in stimulated macrophages, indicating that there are at least two immunologically distinct NO synthases.

Amino Acid Oxidoreductases↗

PubMed1992

Clinical study of bone-related relapse in prostate carcinoma.

Prostate carcinoma is usually highly responsive to initial endocrine therapy. However, when relapse occurs, the subsequent clinical course is very poor. In this study, we tried to reveal the clinical aspects of bone-related relapse in 392 patients who received endocrine therapy for prostate carcinoma. In 17 stage B patients who had relapsed, 76% experienced relapse within 4 years following the start of treatment, 76% within 3 years in 27 stage C patients, and 71% within 2.5 years found in 45 stage D patients. Pre-treatment levels of serum enzymes and initial response of the primary lesion and of serum enzymes failed to predict relapse. The Gleason sum tended to be correlated with relapse. In particular, patients with a Gleason sum of 9-10 had a lower non-relapse rate during the follow-up period than patients with lower sums. With the recent use of more sophisticated measurements of PSA and/or PAP, the reduction rate or interval to normalization of the markers must be more relevant to predicting relapse.

Acid Phosphatase↗

PubMed1992

The relationship between odontoblasts and pulp capillaries in the process of enamel- and cementum-related dentin formation in rat incisors.

The relationship between odontoblasts and pulp capillaries in the process of dentinogenesis was studied in rat lower incisors, both on the labial and lingual sides, using light and transmission electron microscopy. The odontoblasts showed remarkable differences from the apical to the incisal end. Near the apical end of the tooth, "immature odontoblasts", which were thought to be involved in the formation of the mantle dentin, were arranged in a single layer, and continuous capillaries were located just beneath the odontoblasts. In the middle of the tooth, "mature odontoblasts" with highly developed cell organelles and notable processes formed a pseudostratified layer; fenestrated capillaries were found between these cells close to the predentin. The height of the odontoblast layer and the rate of dentin deposition on the labial (enamel-related) side was significantly greater than that on the lingual (cementum-related) side. Near the incisal end, cementum-related odontoblasts gradually decreased in height and number to become "post-odontoblasts" that produced atubular dentin; continuous capillaries were located subjacent to the post-odontoblasts. On the labial (enamel-related) side, however, odontoblasts retained their pseudostratification; fenestrated capillaries were still observed in the odontoblast layer. No atubular dentin was formed on the labial side.

Animals↗

PubMed1992

Effects of hickory-smoke condensate on development of pepsinogen 1-altered pyloric glands in rats.

Hickory-smoke condensate (HSC) is a popular food flavouring in the USA. Available data have suggested that this food additive has tumour-initiating/promoting potential. Accordingly, a commercial HSC has been investigated for its capacity to promote tumours in the rat glandular stomach using pepsinogen 1 (Pg 1)-altered pyloric glands (PAPG) as the marker of preneoplastic lesions. The development of PAPG initiated by a single intragastric administration of N-methyl-N'-nitroso-N-nitrosoguanidine was significantly increased by feeding rats a diet containing 5% HSC; no effect was observed with lower doses (1.25 or 2.5%) of HSC. The results suggest that HSC has weak tumour-promoting potential in the rat glandular stomach.

Animals↗

PubMed1992

Isoelectric point of an ion-penetrable membrane.

The surface potential of an ion-penetrable planar membrane is calculated for the case in which acidic and basic groups are present in the membrane. It is found that when both acidic and basic groups are not uniformly distributed in the direction normal to the membrane, the isoelectric point (the pH value at which the surface potential becomes zero) of the membrane varies with the electrolyte concentration, whereas if both groups are uniformly distributed, the isoelectric point is independent of the electrolyte concentration. As a simple example, we treat a membrane consisting of two layers, in which acidic groups are distributed in the outer layer and basic groups are in the inner layer. Simple equations determining the membrane surface potential as a function of pH and electrolyte concentration and the dependence of the isoelectric point on the electrolyte concentration are presented.

Chemical Phenomena↗

PubMed1992

Carcinogenic tobacco-specific nitrosamines are present at unusually high levels in the saliva of oral snuff users in Sudan.

Exposure to tobacco-specific nitrosamines (TSNA) has been measured in the saliva of 12 users of Sudanese oral snuff (toombak). Using GC coupled to thermal energy analysis, levels of N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were measured before, during and after snuff taking. In addition, two TSNA, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL), were detected in the saliva of tobacco chewers for the first time and were confirmed by GC-MS. Nine out of 10 subjects had detectable saliva levels of total TSNA before chewing (0.01-1.0 micrograms/ml) and immediately following chewing (0.1-2.6 micrograms/ml). During dipping, TSNA concentrations reached microgram/ml levels; (range; number of subjects positive) NNN: (0.6-2.1; 12/12), NAT (0.06-0.5; 2/12), NAB (0.05-1.9; 12/12), NNK (0.06-6.7; 11/12), NNAL (0.05-3.3; 11/12) and iso-NNAL (0.07-0.4; 8/12). These saliva TSNA levels, which are 10-100 times the levels previously reported, are consistent with recent observations of unusually high TSNA levels in Sudanese toombak. As several of these TSNA have been shown to be carcinogenic in animals and epidemiological studies have associated human snuff use with tumours of the oral cavity, these findings draw attention to a significant potential public health hazard.

Adolescent↗

PubMed1992

Extraperitoneal anterolateral discectomy for lumbar disc herniation: indications, techniques, and time-related clinical results.

We analyzed 80 consecutive cases of lumbar disc herniation who underwent an extraperitoneal anterolateral discectomy according to clinical and radiologic parameters. The average follow-up period was 5 1/2 years (range, 1-10 years). The results of 71 patients (89%) were satisfactory through the mid- and long-term follow-up periods, although a very slight decrease in subjective/objective scores and ADL score was found. Satisfactory results were obtained for adolescent and younger male adults and in isolated central or centrolateral herniations with a broad base. From an analysis of the nine reoperated cases, we determined that the contraindications of this technique are a sequestrated or extruded nucleus pulposus and disc protrusion accompanied by posterior dislocation of a vertebral edge fragment. The relative indications include a small, hard posterolateral herniation located just beneath the nerve roots, double-level herniation, disc herniation accompanied by narrow spinal canal, and bulged disc in elder patients. The absolute indications for this surgery are a centrally or centrolaterally protruded disc with a relatively broad base of herniation at single-disc level that is not accompanied by spinal stenosis in adolescent and younger male adults.

Adolescent↗

PubMed1992

Effects of continuous quantitative vibration on rheologic and biological behaviors of the intervertebral disc.

The authors attempted to investigate the effect of vibration on the physiologic behavior of the intervertebral disc from rheologic and biological responses. Using fresh disc-cartilaginous end plate complexes of porcine coccygeal vertebrae, the frequency characteristics of dynamic compressive elastic modulus and dissipated energy were monitored by means of a biomechanical spectrometer. The effect of vibration on proteoglycan synthetic rates and solute transport in the intervertebral disc were analyzed using a radioisotope. When the disc-cartilaginous plate complexes were subjected to sinusoidal vibration with a static load of 5 N and a vibratory load of 3 N, the elastic modulus decreased at 11 Hz compared with 3.5 Hz. After this, it increased again at 35 Hz. The dissipated energy increased rapidly with an increase in frequency. Proteoglycan synthetic rates did not change appreciably down to the inner and outer layers of the anulus fibrosus, but the rate in the nucleus pulposus alone decreased remarkably at 10 Hz and 35 Hz. Solute transport increased as a response to vibration, particularly in the nucleus pulposus. When the intervertebral disc is exposed to vibration for a long period of time, therefore, the proteoglycan content in the nucleus pulposus may be decreased, eventually resulting in disruption of matrix integrity.

Animals↗

PubMed1992

The effect of lactate and pH on proteoglycan and protein synthesis rates in the intervertebral disc.

The intervertebral disc is the largest avascular tissue in the body. Its metabolism is mainly anaerobic, and thus lactate is produced at a significant rate. As a result the lactate concentrations in the center of the disc may be 8-10 times as high as in the plasma. The pH in the disc center is thus acidic. Because low values of pH are known to affect proteoglycan synthesis in other cartilages, the authors measured the effect of lactate levels and pH on 35S-sulphate and 3H-proline incorporation rates in the nucleus of bovine coccygeal discs and in human disc obtained during percutaneous nucleotomy. The maximum incorporation rate occurred at pH 7.2-pH 6.9. Here the rate was 40-50% greater than at pH 7.4. Below pH 6.8 the rate fell steeply, more so for sulphate than for proline. At pH 6.3 the sulphate incorporation rate was around 20 percent that at pH 7.4. The results indicate that proteoglycan synthesis rates in particular are sensitive to extracellular pH, and that the peak rate occurs around the level of pH seen in vivo. Factors that cause lactate levels to rise, such as a fall in O2 levels as the result of smoking or vibration (Holm and Nachemson, 1988) could lead to a fall in proteoglycan synthesis rates, ultimately leading to a fall in proteoglycan content and to disc degeneration.

Animals↗

PubMed1992

Endogenously formed N-nitroso compounds and nitrosating agents in human cancer etiology.

Humans are exposed to preformed N-nitroso compounds (NOC), but also to a wide range of precursors and nitrosating agents which can react in vivo to form potentially carcinogenic NOC and diazo compounds. Nitrite, nitrate and nitrosating agents can also be synthesized endogenously in enzymic reactions mediated by bacteria, activated macrophages and neutrophils. The latter two cell types generate, via the enzyme nitric oxide synthase, the nitric oxide radical that is involved in cytotoxicity, and is believed to be involved in formation of carcinogenic nitrosamines, DNA base deamination and oxidative damage. Thus endogenous NOC formation, DNA damage and gene mutations in humans could occur at various sites of the body such as the stomach and chronically infected or inflamed organs. Sensitive procedures to estimate the exposure of humans to NOC have been developed and applied in ecological and cross-sectional studies. These have shown that inhabitants of high-risk areas for stomach and esophageal cancer, patients with urinary tract infections (at risk for bladder cancer) and Thai subjects infected with liver fluke (at risk for cholangiocarcinoma) had significantly higher exposure to endogenous NOC. Clinical studies have examined the model of stomach carcinogenesis based on intragastric nitrosation, but the precise roles of bacterial overgrowth and of Helicobacter pylori infection in NOC synthesis and/or inducing oxidative stress in stomach mucosa remain to be clarified. Together these results support the role of NOC and other nitrite-derived mutagens in human cancer etiology, in particular when exposure starts early in life and persists over a long period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Bile Duct↗

PubMed1992

An interpretation of cell separation mechanism on polyamine graft copolymers.

Interaction between polyamide microcapsules having different balances of negative and positive charges on their surface, that is, different isoelectric points and copolymers with different numbers of polyamine macromer of a definite chain length grafted on poly(2-hydroxyethyl methacrylate) backbone was studied by measuring the amount adhered of the microcapsules onto the surface of copolymer-coated glass beads at different pH values. Maximum microcapsule adhesion was observed for a proper combination of microcapsule and copolymer to suggest that separation of a specified cell population from others on the surface of copolymer-coated glass beads can be explained in terms of preferential adhesion through electrostatic interaction of the specified cells with the copolymer.

Cell Separation↗

PubMed1992

Effect of systemic L-arginine administration on hemodynamics and nitric oxide release in man.

The effects of L-arginine administration on systemic hemodynamics and plasma concentrations of neuro-endocrine hormones and amino acids were investigated in 10 normotensive healthy volunteers. Nitrite/nitrate in urine and cyclic guanosine monophosphate (c-GMP) in plasma were also measured as indicators of release of nitric oxide (NO). L-arginine administration (30 g/300 ml/30 min) caused hypotension (mean arterial pressure; 79.3 +/- 3.9 mmHg fell to 68.8 +/- 2.2 mmHg) with tachycardia (62.3 +/- 2.3 beats/min increased to 67.5 +/- 1.9 beats/min). The plasma concentration of L-arginine before administration was 98.8 +/- 8.2 mumol/l and increased to 7263 +/- 567 mumol/l 20 min after administration. Cardiac output also increased to 127.2 +/- 3.9% by L-arginine administration. Total peripheral resistance was calculated to fall to 65.9 +/- 2.0%. L-arginine administration slightly changed several hormones, but all values were within normal ranges. Nitrite/nitrate in urine increased 142.1 +/- 12.4% compared to the values before L-arginine administration. Plasma concentrations of c-GMP and L-citrulline, the by-product of NO from L-arginine, were also significantly increased by L-arginine administration. All our results provide evidence for the first time that systemically administered L-arginine releases NO in man.

Adult↗

PubMed1991

Opisthorchis viverrini infestation and endogenous nitrosamines as risk factors for cholangiocarcinoma in Thailand.

Cholangiocarcinoma (CCA) is one of the most common cancers in north-east Thailand and has been associated with infestation by the liver fluke Opisthorchis viverrini (OV). Two samples of 12-hr overnight urine (after dosing with proline and ascorbic acid or proline alone) were collected from 20 inhabitants from each of 5 contrasting incidence areas for CCA. The incidence of CCA was not correlated with either the amount of NPRO or other nitrosamino acids, endogenous nitrosation potential (difference in NPRO levels between proline dose and proline and ascorbic dose), or nitrate level. However, when urinary levels of nitrosamino acids were compared in subjects living in high-risk areas, subjects who were positive for OV antibody excreted significantly more (p less than 0.01) NPRO (12.3 +/- 18.7 micrograms/12 hr) after proline ingestion than those who were negative (3.5 +/- 3.2 micrograms/12 hr). After ingestion of ascorbic acid, the NPRO levels in the positive subjects were significantly reduced (p less than 0.01) to 2.4 +/- 2.0 micrograms/12 hr, suggesting that endogenous nitrosation of proline was inhibited. Thus, endogenous nitrosation potential estimated from the difference between NPRO and the sum of nitrosamino acids excreted in the 2 urine samples was significantly higher in subjects positive for the OV antibody. Small amounts of pre-formed nitrosamines were found in fermented fish and pork food items, which are consumed frequently in the high-risk area for CCA. These results suggest that the interaction between chemical carcinogens, especially nitrosamines, and OV infestation may play a role in the development of cholangiocarcinoma in Thailand.

Adenoma, Bile Duct↗

PubMed1991

Malignant amelanotic melanoma of the esophagus.

The clinical, histological, and electron microscopic features of a case of malignant amelanotic melanoma of the esophagus are described. Amelanotic melanoma is difficult to distinguish from other malignant lesions, but in our case electron microscopy was helpful in the diagnosis.

Diagnosis, Differential↗

PubMed1991

Temperature- and ionic strength-induced conformational changes in the lipid head group region of liposomes as suggested by zeta potential data.

Neutral liposomes composed of DMPC (dimyristoylphosphatidylcholine), DPPC (dipalmitoylphosphatidylcholine) or DSPC (distearoylphosphatidylcholine) are found to exhibit non-zero zeta potentials in an electric field even when they are dispersed in solution at pH 7.4. A model for the orientation of lipid head groups is proposed to explain the observed non-zero zeta potentials. The dependence of the zeta potential on temperature and ionic strength is analyzed via this model to obtain the information on the direction of the lipid head group in the liposome surface region. The direction of the lipid head group is found to be sensitive to the temperature and the ionic strength of the medium. At low ionic strengths, the phosphatidyl groups are located at the outer portion of the head group region. At constant temperature, as the ionic strength increases, the choline group approaches the outer region of the bilayer surface while the phosphatidyl group hides behind the surface. At the phase transition temperature of the lipid, the phosphatidyl group lies in the outer-most region of the surface and the choline group is in the inner-most region.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1991

On the electrophoretic mobility of biological cells.

A theoretical study has been performed on the electrophoretic mobility of a large colloidal particle with a surface charge layer as a model for biological cells. An approximate mobility expression is derived which is applicable to the general case of an arbitrary distribution of membrane-fixed charges. This expression consists of two terms: the first is a weighted average of potentials over the surface charge layer, while the second is that of the volume density of membrane-fixed charges and does not depend on the electrolyte concentration. At high electrolyte concentrations (corresponding to physiological conditions), where the potentials are very low owing to the shielding effects of electrolytes, the first term diminishes so that the mobility is determined mainly by the second term. This means that a particle with zero surface potential can exhibit a non-zero mobility, in contrast to the prediction from the classical Smoluchowski theory. Comparison is also made with the theory of Hermans and Fujita for the electrophoresis of polyelectrolytes.

Cell Membrane↗