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Biomedical subjects

N Nakayama

Publications and source records attributed to N Nakayama.

At least 19 recordsLinked to original sources
PubMed1997

Adsorption Characteristics of Silica Gels Treated with Fluorinated Silylation Agents

Branched-chain polyfluorosilane (monochlorodimethyl[4,4-bis(trifluoromethyl)-5,5,6,6,7,7,7-heptafluoroheptyl)-bonded silica gels were prepared. The surface properties of the silica gels modified with various organic silanes were evaluated by the adsorption density of polar and nonpolar gases calculated from adsorption isotherms of nitrogen, carbon dioxide, and normal butane gases. The polyfluorocarbon-bonded silica gel surface was found to be both hydrophobic and oleophobic in nature, whereas the hydrocarbon-bonded silica gel surface was characterized only as hydrophobic. The trifunctional fluorinated silane provides the silica gel surface with a more hydrophilic nature than the monofunctional silane because of the formation of a denser polymeric coating layer with a larger number of silanols.

Journal Article↗
PubMed1997

Copper concentration in hyperintense hepatocellular carcinomas of Long-Evans cinnamon rats on T1-weighted images.

The Long-Evans Cinnamon (LEC) rat has abnormal intrahepatic copper accumulation and spontaneously develops hepatocellular carcinomas following hereditary hepatitis. The hepatocellular carcinomas are very similar to human well-differentiated hepatocellular carcinoma in histopathological features and on MR images. Copper is believed to be one of the causes of hyperintensity of hepatocellular carcinomas compared to surrounding non-cancerous tissues on T1-weighted MR image. Eight LEC rats were studied by MR imaging. We measured copper concentrations from the hepatocellular carcinomas and surrounding non-cancerous liver tissues. Signal intensity of hepatocellular carcinomas without cystic areas was iso- to slightly hyperintense relative to surrounding non-cancerous tissues on T1-weighted images. Histopathologically, most of the tumors resembled human highly or well-differentiated hepatocellular carcinomas. Copper concentrations of the hepatocellular carcinomas were lower than the surrounding non-cancerous liver tissues. Copper may not be the cause of increased signal intensity typically observed on T1-weighted images of hepatocellular carcinomas.

Animals↗
PubMed1996

A fluorometric assay for measuring deamidase (lysosomal protective protein) using high-performance liquid chromatography.

A rapid and sensitive assay method for the determination of deamidase activity is reported. This method is based on fluorometric detection of a dansylated dipeptide, 5-dimethylaminonaphthalene-1-sulfonyl-D-Tyr-Val (N-Dns-D-Tyr-Val), enzymatically formed from the substrate 5-dimethylaminonaphthalene-1-sulfonyl-D-Tyr-Val-NH2 (N-Dns-D-Tyr-Val-NH2), after separation by high-performance liquid chromatography (HPLC) using a C-18 reversed-phase column by isocratic elution. This method is sensitive enough to measure N-Dns-D-Tyr-Val at concentrations as low as 100 fmol, yields highly reproducible results and requires less than 8.5 min per sample for separation and quantitation. The optimum pH for deamidase activity was 4.0-4.5. Greater than 5 mM of reduced glutathione was needed for maximal enzyme activity. The Km and Vmax values were respectively 125 microM and 14.12 pmol/micrograms/h with the use of enzyme extract obtained from mouse spleen. Deamidase activity was strongly inhibited by Ag+, Cu2+, diisopropylfluorophosphate, and p-chloromercuriphenylsulfonic acid. Among the organs examined in a mouse, the highest specific activity of the enzyme was found in spleen. The sensitivity and selectivity of this method will aid in efforts to examine the physiological role of this enzyme.

Animals↗
PubMed1996

Hepatocyte growth factor and c-met expression in Long-Evans Cinnamon rats with spontaneous hepatitis and hepatoma.

The Long-Evans Cinnamon (LEC) rat is characterized by the spontaneous onset of acute and chronic hepatitis, followed by occurrence of liver cancer, and is thus able to provide a unique experimental model for human genetical liver disease, Wilson's disease. Hepatocyte growth factor (HGF) is a potent hepatotrophic factor in liver regeneration, and its expression is up-regulated in response to liver injuries. We found that the plasma HGF level in LEC rats rose markedly during the fulminant hepatitis phase, fell during the phase of chronic/cholangiofibrosis, and fluctuated during the hepatoma phase. Immunohistological staining of the liver revealed that the number of HGF-positive cells increased remarkably during the fulminant hepatitis phase, and that many of these cells were localized at the portal triads. Fewer HGF-positive cells were observed during the phase of chronic hepatitis. The surface of the hepatocellular carcinoma (HCC) cells and the cytoplasm of the nonepithelial cells in cancerous liver tissues were HGF-positive. The HGF-messenger RNA (mRNA) level in the liver rose in the fulminant hepatitis phase, fell in the chronic hepatitis phase, and was intermediate or high during the hepatoma phase. The expression of c-met mRNA was strong in the tissues of LEC rats with fulminant hepatitis and, especially, in the cholangiofibrosis tissues. c-met mRNA was also detected in HCCs. These results suggest that the HGF-c-met system may play an important role in the regeneration of hepatocytes as well as in the development of HCC in paracrine or autocrine mechanisms.

Animals↗
PubMed1996

Cytochrome P450foxy, a catalytically self-sufficient fatty acid hydroxylase of the fungus Fusarium oxysporum.

We have purified membrane-bound fatty acid (omega-1-omega-3) hydroxylase of the fungus Fusarium oxysporum MT-811 and found that the activity depends on a single polypeptide with an apparent M(r) value of 118,000. The purified hydroxylase exhibited spectral characteristics of cytochrome P450 (P450), and could catalyze the hydroxylation without the aid of any other proteinaceous components, such as NADPH-P450 reductase. These properties of the fungal hydroxylase are the same as those of bacterial P450BM3 of Bacillus megaterium, a catalytically self-sufficient fused protein of P450 and its reductase. Other properties of the two enzymes, such as molecular weight, high catalytic turnover, and the regiospecificity of the hydroxylating position, were also almost identical. Further, the fungal hydroxylase reacted with the antibody to P450BM3. It was thus shown that the fungal fatty acid hydroxylase reacted with the antibody to P450BM3. It was thus shown that the fungal fatty acid hydroxylase structurally and functionally bears a close resemblance to P450BM3, although it is membrane-bound, unlike the bacterial counterpart. On the other hand, a unique phenomenon was found with the fungal hydroxylase: its NADPH-cytochrome c- or NADPH-menadione reductase activity was enhanced enormously upon binding of its substrate (fatty acid). This appears to be the first instance in which the reactivity of P450 reductase against an artificial electron acceptor was enhanced by the binding of the substrate (to be hydroxylated) to P450. These results raise interesting questions about the molecular evolution of P450. Here we term the fungal hydroxylase cytochrome P450foxy.

Blotting, Western↗
PubMed1996

The effect of sodium bicarbonate on CBF and intracellular pH in man: stable Xe-CT and 31P-MRS.

The effects of sodium bicarbonate on cerebral blood flow (CBF) and intracellular pH were studied in five normal volunteers. CBF and intracellular pH were measured by stable xenon computed tomography and phosphorus-31 magnetic resonance spectroscopy (31P-MRS) respectively. Each patient received 7% sodium bicarbonate (3.5 ml/kg body weight) infused intravenously for 15 minutes. Before and after this injection, CBF intracellular pH and physiological parameters were measured. CBF and PaCO2 were significantly increased. On the other hand, hematocrit and intracellular pH were decreased. These result suggests that three factors are thought to contribute to increase CBF during administration of sodium bicarbonate in humans: 1) arterial dilatation in response to carbon dioxide 2) an decrease of hematocrit 3) intracellular acidosis.

Acid-Base Equilibrium↗
PubMed1996

[Two cases of ossified spinal meningioma].

It is generally known that meningioma has histological pleomorphism and ossification is one of them. In the cases of spinal meningioma, osteoblastic type is rare. We encountered two different types of ossified spinal meningioma. Two cases of ossified spinal meningioma are reported in this paper. One case is that of a 45-year-old male who had a sudden transient tetraparesis with a tumor located in the upper cervical spinal column. The tetraparesis was caused by the patient's head having been hit. Another case is a 74-year-old female, who had progressive paraparesis and hypesthesia in her lower extremities, with a tumor located in the 9th thoracic spinal column. The MRI findings in these cases suggested that an ossified area was included in the tumor. We performed surgical therapy in both cases, and an operative finding was that these tumors had a very hard component. Histopathological diagnosis in both cases was meningioma. The former included isolated matured bone tissue with fat marrow mixed with the tumor tissue, and the latter included scattered matured lamellar bone tissue. These tumors are considered to be osteoblastic in type.

Aged↗
PubMed1995

Insulin resistance in skeletal muscle of the male Otsuka Long-Evans Tokushima Fatty rat, a new model of NIDDM.

The Otsuka Long-Evans Tokushima Fatty rat is a new inbred obese strain with a late onset and chronic course of spontaneous hyperglycaemia in the male, and is considered to be a model of non-insulin-dependent diabetes mellitus [1, 2]. Fat distribution analysis showed a typical accumulation of intra-abdominal visceral fat in Otsuka Long-Evans Tokushima Fatty rats compared with a control strain, Long-Evans Tokushima Otsuka rats. To examine the insulin sensitivity of Otsuka Long-Evans Tokushima Fatty rats, we performed euglycaemic hyperinsulinaemic clamp experiments in vivo in rats under anaesthesia on this strain and on Long-Evans Tokushima Otsuka rats. The Otsuka Long-Evans Tokushima Fatty rats showed lower values for the glucose infusion rate (60% of the control at 12 weeks old and 20-30% of the control at 18, 24, 30 and 39 weeks old) than age-matched controls, indicating the development of insulin resistance with age. Hindlimb perfusion experiments in vitro also showed a 45% decrease of insulin-stimulated glucose uptake in Otsuka Long-Evens Tokushima Fatty rats in the diabetic stage. These results indicate that insulin resistance exists in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats. To obtain information on the mechanism of insulin resistance in the skeletal muscle of Otsuka Long-Evans Tokushima Fatty rats, the insulin binding, autophosphorylation and tyrosine kinase activity of their partially-purified insulin receptors in vitro were compared with those from control rats. The results showed no marked differences in these insulin receptor functions between diabetic and control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1995

Structures of nine oxygenated 4-methylene sterols from Hachijo marine sponge Theonella swinhoei.

Nine new sterols have been isolated from a marine sponge, Theonella swinhoei. Of these, seven sterols were found to be conicasterol derivatives [(24R)-4-methylene-24-methyl-8(14)-cholesten-3 beta-ol] oxygenated at carbon-7 and/or carbon-15. The other two were (24R)-7 beta,8 beta-epoxy-14 alpha-methoxy-4-methylene-24-methylcholestan- 3 beta-ol and (24R)-8,14-seco-8,14-dioxo-4-methylene-24-methylcholestan-3 beta-ol.

Animals↗
PubMed1995

Mice deficient for the IL-3/GM-CSF/IL-5 beta c receptor exhibit lung pathology and impaired immune response, while beta IL3 receptor-deficient mice are normal.

The receptors for IL-3, GM-CSF, and IL-5 share a common beta subunit (beta c), and mice have an additional IL-3 beta subunit (beta IL3). We have independently generated mice carrying null mutations of each molecule. beta c mutant bone marrow showed no response to GM-CSF or IL-5, whereas IL-3 stimulation of beta c or beta IL3 mutant bone marrow was normal. beta c mutant mice showed lung pathology consisting of lymphocytic infiltration and areas resembling alveolar proteinosis, and also exhibited low basal numbers of eosinophils. Infection of beta c mutant mice by Nippostrongylus brasiliensis resulted in the absence of blood and lung eosinophilia. Animals repopulated with beta c mutant bone marrow cells showed slower leukocyte recovery and reduced eosinophil numbers. These data define the role of beta c in vivo, and show a phenotype that is likely to be the cumulative effect of loss of GM-CSF and IL-5 stimulation.

Animals↗
PubMed1995

Differing distribution of hepatocyte growth factor-positive cells in the liver of LEC rats with acute hepatitis, chronic hepatitis and hepatoma.

Using anti-rat hepatocyte growth factor (HGF) antibody, we investigated the distribution of HGF-positive cells in the liver tissues of LEC rats at various phases of liver diseases. During the phase of fulminant hepatitis, HGF-positive cells increased remarkably, and many of them were localized at the portal triads; these cells were identified from their shape as non-epithelial cells. A reduced number of HGF-positive cells was observed during the phase of chronic hepatitis, while no HGF-positive cells were seen in the tissue of cholangiofibrosis. During the phase of carcinoma, staining revealed that both the hepatocellular carcinoma cells and the non-epithelial cells in cancerous liver tissue were HGF-positive. These results suggest that, in LEC rats, HGF may play an important role in the regeneration of hepatocytes as well as in the development of hepatocellular carcinoma.

Acute Disease↗
PubMed1995

Monamidocin, a novel fibrinogen receptor antagonist. I. Production isolation, characterization and structural elucidation.

Monamidocin, a novel fibrinogen receptor antagonist, has been isolated from the culture broth of Streptomyces sp. NR 0637 BY carbon adsorption, n-BuOH extraction, SP-Toyopearl, silica gel 60 silanised and Sephadex LH-20 column chromatographies and preparative HPLC. The molecular formula of monamidocin has been determined to be C15H22N4O4 from HRFAB-MS and 13C NMR spectral data. The structure of monamidocin has been determined to be N-[(S)-5-guanidino-2-hydroxypentanoyl]-L-phenylalanine by 2D NMR experiments.

Chemical Phenomena↗
PubMed1995

Structural elucidation of aculeximycin. IV. Absolute structure of aculeximycin, belonging to a new class of macrolide antibiotics.

Aculeximycin (1) produced by Streptosporangium albidum possesses a 30-membered polyhydroxy macrocyclic lactone and five sugars including aculexitriose. We have described the determination of the planar structure of N-diacetylated aculeximycin (2) using degradation products, which were obtained by DBU-methanol treatment, ozonolysis and periodative oxidation. In order to determine the relative and absolute configurations of aculeximycin, first, the relative and absolute configurations of the degradation products 10, 11, 12 and 13 were determined. Rychnovsky's method was very useful to determine the relative configurations of these degradation products, and CD exciton chirality and the modified Mosher's methods were applied to determine their absolute configurations. From these results, fourteen out of the twenty asymmetric centers in aculeximycin were determined to be 5S, 17R, 20S, 21R, 23R, 24R, 29S, 30R, 31S, 34R, 35S, 36S and 37R. The absolute configurations at C-14 and C-15 on the hemiketal ring were confirmed using 12 obtained by the partial glycol bond cleavage of 9. Absolute configurations of the remaining asymmetric centers were determined by spectral analysis of 15 and NOE experiment on 1. From these results, the absolute configuration of 1 was determined to be 5S, 7R, 10S, 11R, 14R, 15S, 17R, 19R, 20S, 21R, 23R, 24R, 25S, 29S, 30R, 31S, 34R, 35S, 36S and 37R.

Anti-Bacterial Agents↗
PubMed1995

[A case of surgical retrieve of migrated microcatheter].

This is a report of an accidental breakaway of a microcatheter during endovascular embolization for cerebral arteriovenous malformation occurring in a 48-year-old female. She had a sudden onset of cerebral herniated signs caused by a large hemorrhage in the region of the right parietal lobe. An angiogram showed a large arteriovenous malformation in the same region. 48 days after emergency evacuation of the hematoma and clipping of a feeding artery, we performed endovascular embolization using a microcatheter as assistant therapy for total removal of the nidus. However, accidentally, the microcatheter broke and migrated to the distal middle cerebral artery. Although we tried to retrieve the catheter using a loop snare, we had no success. We eventually retrieved it by open surgery next day. Fortunately the migrated catheter could be seen through a cortical artery, so after trapping it by using elastic thread and cutting off the artery we were able to extract the migrated catheter. Finally we were able to remove the nidus totally without other complications. Since breaking and migration of a microcatheter is a rare but possible accident, we should be prepared to cope with it appropriately.

Catheterization↗
PubMed1995

[Expression of hepatocyte growth factor (HGF) in LEC rats at various phases of hepatitis and hepatoma].

The role of hepatocyte growth factor (HGF) in LEC rats were investigated at various phases of liver diseases by the detection of HGF expression, using ELISA assay, mRNA analysis and immunohistochemistry. Levels of plasma HGF increase in the fulminant hepatitis phase, decreased during chronic/cholangiofibrosis phase, and in some LEC rats, high levels of HGF were observed in hepatoma phase. HGF mRNA level in the liver was very high in fulminant hepatitis phase and low in chronic hepatitis phase. In hepatoma phase, HGF mRNA level was intermediate or high in the liver. In fulminant hepatitis phase, HGF mRNA level in the lung was slightly increased, while it was almost stable in the kidney in all the conditions studied. Immunohistochemical studies revealed that the frequency of HGF positive cells increased remarkably in fulminant hepatitis phase, and that many of them were located at the portal triads. Fewer HGF-positive cells were found in chronic hepatitis phase and were not found in the tissue of cholangiofibrosis. HGF was found in the surface of hepatocellular carcinoma cells and in the cytoplasm of the non-epithelial cells in cancerous liver tissues. HGF-positive cells appeared 24h after partial hepatectomy, diffusely, and HGF mRNA increased earlier in the kidney and lung than in the liver. Moreover, HGF mRNA level was higher in the lung than in the liver. These results suggest that in the natural course of spontaneous hepatitis and hepatoma in LEC rats, HGF is expressed mainly in the liver and that HGF may play an important role in the regeneration of hepatocytes in a paracrine manner. In contrast, after partial hepatectomy, HGF produced in the lung may be effective for liver regeneration in an endocrine manner.

Animals↗
PubMed1995

[Proton MR spectroscopy in patients with unilateral temporal lobe epilepsy].

The authors assessed proton magnetic resonance spectroscopy (1H-MRS) in patients with unilateral refractory temporal bole epilepsy. The subjects consisted of 20 patients (those with brain tumors, trauma, malformations or definite organic lesions were excluded) and 10 normal volunteers. 1H-MRS and MRI were performed using a 1.5 tesla machine. 1H-MRS was achieved using point-resolved spectroscopy (PRESS) or the stimulated echo acquisition mode (STEAM), and a 3 x 3 x 3 cm volume of interest was positioned at the hippocampus. N-Acetyl-aspartate (NAA) and choline-containing substance (Cho) signals were evaluated. The results showed decreased NAA and elevated Cho or asymmetry of both NAA and Cho in the epileptogenic focus in 19/20 cases. The reductions in NAA presumably reflect neuronal loss, while the elevation of Cho probably represents membrane break down within the lesion. These abnormalities were observed in 19/20 cases (95%), whereas abnormal magnetic resonance imaging was detected in only 6/20 (30%) of the patients. Thus, 1H-MRS appears to be a useful, non-invasive modality for evaluating metabolic changes in epileptogenic foci, and these metabolic changes can serve as a more sensitive indicator than magnetic resonance imaging.

Adolescent↗
PubMed1995

Mechanisms of the potent and long-lasting antihypertensive action of the new calcium channel blocker pranidipine. Evidence for strong affinity to the calcium channels or membranes.

To elucidate the mechanisms of the potent and long-lasting antihypertensive action of pranidipine (CAS 99522-79-9, OPC-13340), a wash-out experiment in isolated rat aorta preparations and a displacement binding experiment of (+)[3H]PN200-110 (isradipine) with pranidipine and other dihydropyridines to porcine skeletal T-tubules was conducted. It was revealed that the inhibition of KCl-induced contraction by pranidipine remained complete even after washing out the drug 9 times. Also, pranidipine had the lowest Ki value for (+)[3H]PN200-110 binding in skeletal T-tubules. The lipophilicity of pranidipine measured by octanol-buffer partition coefficient was the highest among the tested compounds, and the order of lipophilicity coincided with the order of potency in the displacement binding experiments. These results suggest that pranidipine has a very high affinity to Ca channels or to T-tubule membranes, and strongly support the "membrane-bilayer pathway hypothesis" which assumes the partitioning of the drug into the lipid bilayer before drug binding to Ca channels as an explanation of the potent and long-lasting action of pranidipine compared with other dihydropyridines.

Animals↗