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Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 163 records · Page 9Linked to original sources
PubMed2001

Clinical implication of serial leptin measurement in subjects with type 2 diabetes mellitus.

Plasma leptin concentration is closely associated with body fat in humans, with energy restriction inducing a greater decrease in plasma leptin than in body fat. Since adequate energy restriction is mandatory in diet therapy of diabetes mellitus especially in obese subjects, the present study was undertaken to evaluate the clinical implication of serial leptin measurement in the management of diabetic patients. Fifty-four consecutive subjects with type 2 diabetes, who were subjected to adjusted energy restriction during hospitalization, were enrolled in the study. During their hospitalization period (24+/-4 days), plasma leptin concentrations decreased from 6.9+/-0.7 to 5.7+/-0.6 microg/l (P<0.0001) in the overall subjects, and the %change in plasma leptin (-13.9%) was greater than the %changes in body mass index (BMI) and percent body fat (-1.7% and -4.7%, respectively). The %change in plasma leptin was positively correlated with the %changes in BMI and plasma C-peptide (r=0.526, P<0.0001 and r=0.446, P<0.002, respectively) and negatively with a %change in plasma ketone bodies (r=-0.516, P<0.005). Multiple regression analysis revealed that the %changes in BMI and plasma C-peptide were independent determinants of the %change in plasma leptin. In addition, 38 subjects were followed up after discharge. Three months after discharge, plasma leptin concentrations significantly increased by 25.6%, which was again much greater than the %change in BMI (+0.9%). In 28 subjects who showed increase in plasma leptin levels after discharge, BMI was also increased. In contrast, the remaining 10 subjects without the increase in plasma leptin kept their BMI unchanged. Throughout the observation period, the changes in plasma leptin were prominent in the subjects with BMI greater than 25 kg/m2. In conclusion, plasma leptin concentrations showed greater changes than the alterations in anthropometric indexes during the observation period. Serial leptin measurement may be useful to estimate adherence to energy restriction especially in obese subjects with type 2 diabetes.

Adipose Tissue↗
PubMed2001

Na+-dependent recovery of intracellular pH from acid loading in mouse colonic crypt cells.

The membrane transport mechanism for regulating the intracellular pH value (pHi) was investigated in mouse distal colon crypt cells. pHi was measured by microfluorometry in an isolated crypt fragment loaded with the pH-sensitive fluoroprobe, 2',7'-bis-(2-carboxyethyl)-5-(6) carboxyfluorescein. The pHi recovery process after acid loading induced by a 40 mM NH4Cl prepulse was almost totally dependent on Na+ in both the presence and absence of CO2/HCO3- in the perfusion solution. In the CO2/HCO3(-)-free, HEPES-buffered solution, amiloride partially inhibited the pHi recovery rate from acid loading with an ED50 value of 15 microM and maximum inhibition of 83%. In a CO2/HCO3- solution, amiloride inhibited the pHi recovery rate with an ED50 value of 18 microM, which was similar to that in the HEPES-buffered solution, while the rate of pHi recovery remaining in the presence of the maximum effective concentration of amiloride was significantly larger than that in the HEPES-buffered solution. The Na+-dependent pHi recovery from the acid loading was significantly less (by 18%) in the presence of forskolin. These results suggest that the pHi recovery from acid loading was mediated by 1) amiloride-sensitive Na+/H+ exchanger, 2) the amiloride-insensitive Na+/H+ exchanger, and 3) the Na+- and HCO3(-)-dependent acid extruder. The pHi recovery could be inhibited by cAMP.

Amiloride↗
PubMed2001

Possible involvement of nitric oxide in signaling pigment dispersion in teleostean melanophores.

The possible involvement of nitric oxide (NO) in regulating the motile activities of teleostean melanophores was studied in the dark chub Zacco temmincki (Cyprinidae, Cypriniformes) and in the translucent glass catfish Kryptopterus bicirrhis (Siluridae, Siluriformes). NO donors, including (+/-)-(E)-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexaneamide (NOR1), molsidomine (MSD), sodium nitroprusside (SNP) and glyceryl trinitrate (GTN), had no pigment-aggregating action on melanophores, but actively dispersed melanosomes in those cells. Among those reagents, NOR 1, a spontaneous releaser of NO, was the most effective. Inhibitors for nitric oxide synthase (NOS), i.e. N omega-nitro-L-arginine methyl ester (L-NNA), N omega-nitro-L-arginine (L-NAME) and N omega-monomethyl-L-arginine (L-NMMA), showed melanosome-aggregating effects. A membrane-permeable analogue of cyclic guanosine-3',5'-monophosphate (8-Br-cGMP) was effective in dispersing melanosomes. The sum of these results suggests that NO plays an active role in the elaborate control of color changes in teleosts by dispersing pigment in melanophores via activation of soluble guanylyl cyclase to increase cytosolic levels of cGMP.

Animals↗
PubMed2001

Electrothermal vaporization on a tungsten filament for the determination of arsenic in chloride solutions by low-pressure helium ICP-MS.

A combined method of electrothermal vaporization and low-pressure helium ICP-MS was developed for the determination of traces of arsenic in chloride solutions, because serious spectral interference occurred in conventional argon ICP-MS. On a tungsten filament was placed 5 microl of a sample and heated electrothermally to remove the solvent. The resulting residue on the filament was covered with a vaporization chamber, and after reducing the pressure to ca. 5 Torr, it was rapidly heated by discharging a high-capacity condenser (0.22 F). The vapor of arsenic was transferred to a helium plasma with a stream of carrier gas for the determination. The background was not observed at m/z of 75, which allowed the determination of arsenic at ng/ml levels in chloride solutions. Sodium chloride significantly enhanced the intensity of the arsenic signal, whereas other chlorides, including KCl, MgCl2, CaCl2 and NH4Cl, suppressed the analytical signals. This enhancement due to sodium ions seems to be a peculiar phenomenon to the helium ICP. The proposed method can be applied to direct determinations of as low as 0.9 ng/ml of arsenic in seawater.

Journal Article↗
PubMed2001

Spectroelectrochemical characterization of Si-bridged diphenylamines: influence of Si-bridging upon electronic structures of diphenylamines.

Spectroelectrochemical properties of monosilane bridged diphenylamine (5,10-dihydro-2,8-diphenyl-5, 10,10-trimethylphenazasiline, Phenaz) and disilane bridged diphenylamine (2,8-diphenyl-10,11-dihydro-10,11-disila-5,10,10,11,11-pentamethyldibenzo[b,f]azepine, DSiAzep) were investigated. The electrochemical oxidation of Phenaz was reversible and its cyclic voltammogram was almost the same shape as that of diphenylamine (DPA). The electrochemical oxidation of DSiAzep was followed by irreversible reactions leading to the cleavage of the Si-Si bond. On electrochemical oxidations of Phenaz and DPA, the formation of a stable radical cation was observed with UV-Vis spectroscopy. In comparison with the absorption characteristics of oxidized radical cations, it was seen that the oxidized radical cation of Phenaz was more delocalized than that of DPA. In the same way, absorption characteristics of oxidized DSiAzep were observed to be different from those observed in Phenaz and DPA.

Journal Article↗
PubMed2001

C282Y and H63D mutations in the HFE gene have no effect on iron overload disorders in Japan.

OBJECTIVE: The gene responsible for hereditary hemochromatosis close to the human leukocyte antigen A locus was previously identified and designated as HFE. This study was performed to evaluate the clinical significance of two mutations, C282Y and H63D of HFE, in Japanese patients with hepatic iron overload. PATIENTS AND METHODS: We examined C282Y and H63D in 11 patients with primary hemochromatosis, 94 patients with chronic hepatitis C, 54 patients with miscellaneous liver diseases, and 151 healthy volunteers. The HFE gene region of DNA samples extracted from peripheral leukocytes was amplified by polymerase chain reaction. Restriction enzyme analysis was performed using SnaBI for C282Y and BclI for H63D. Direct sequence analysis was then performed when products suggested the presence of a mutation. RESULTS: All the subjects studied were free from C282Y. None of the patients with hemochromatosis had H63D. One patient with chronic hepatitis C was homozygous, and 4 patients were heterozygous for H63D. Two patients with alcoholic liver disease were heterozygous for H63D. The prevalence of chromosomes with H63D was 6/188 (3.2%) in patients with chronic hepatitis C, 2/108 (1.9%) in patients with miscellaneous liver diseases, and 8/302 (2.6%) in healthy volunteers. These differences were not significant. CONCLUSION: Our results suggested that neither C282Y nor H63D in HFE affect Japanese patients with hemochromatosis or chronic hepatitis C.

Adult↗
PubMed2001

Trisomy 8 involved in myelodysplastic syndromes as a risk factor for intestinal ulcers and thrombosis--Behçet's syndrome.

Only 12 myelodysplastic syndrome (MDS) cases with Behçet's syndrome have been previously reported and trisomy 8 was found to have accumulated in all these patients. Five of the cases had complications in the form of multiple intestinal ulcers, which is one of the symptoms of Behçet's syndrome. To investigate the relationship between trisomy 8 and multiple intestinal ulcers in MDS patients, we analyzed 46 MDS cases treated in our hospital over the last decade, and trisomy 8 was observed in eight of them. Three of these cases had complications of both multiple intestinal ulcers and thrombosis, and two cases showed episodes of thrombosis without intestinal ulcers. All these five cases featured trisomy 8, while the other 38 MDS patients without trisomy 8 had no episode of either intestinal ulcer or thrombosis. Two of the three cases suffering from multiple intestinal ulcers were treated with granulocyte-colony stimulating factor (G-CSF), which resulted in aggravation of the symptoms. Although the influence of G-CSF on such symptoms in MDS patients with trisomy 8 remains unclear, it seems advisable to exercise caution in the use of G-CSF when an MDS patient with trisomy 8 has intestinal ulcers or thrombosis.

Adult↗
PubMed2001

All-trans retinoic acid (ATRA) differentiates acute promyelocytic leukemia cells independently of P-glycoprotein (P-gp) related multidrug resistance.

Here the relationship between all-trans retinoic acid (ATRA)-resistance and P-glycoprotein (P-gp)-associated multidrug resistance (MDR) is discussed in acute promyelocytic leukemia (APL). First, the remission rates of ATRA therapy are similar in relapsed/refractory APL to the preceding chemotherapy given and in newly diagnosed APL. Second, MDR1 cDNA-transduced NB4 (NB4/MDR) cells accumulate less Rhodamine-123 (Rh123) than NB4 cells, but there is no difference in the intracellular ATRA concentration between them. PSC833 or MS209. MDR modifiers, increases the intracellular accumulation of Rh123 in NB4/MDR and APL cells expressing P-gp, but not of ATRA. Third, the expression of CD11b, the NBT reduction activity, the proportion of apoptotic cells and the morphology are not different between NB4/MDR and NB4 cells, and between APL cells expressing P-gp and not. APL cells express little P-gp, and mainly express CD33 but no CD34. Despite previous reports that ATRA-resistant APL cells express more P-gp than ATRA-sensitive ones, P-gp and ATRA-resistance seems to exist independently.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Some biological and biochemical activities of resormycin, a novel herbicidal antibiotic.

Biological and biochemical activities of resormycin were studied using unicellular green algae, Selenastrum capricornutum (abbreviated as Selena.), as a test organism. Resormycin inhibited the growth in vitro of Selena. more strongly in the dark than in the light. A weaker but more photo-stable derivative, (+/-)-2,3-dihydro-resormycin, showed more long-lasting activity against Selena. in the light. Resormycin started killing Selena. only after exposure for 2 days and longer, even at high concentrations. Resormycin at concentrations near IC50 rapidly inhibited incorporation of 3H-leu, but not 3H-UR or 3H-TdR, into the TCA insoluble fraction of Selena. Herbicidal activity of resormycin was confirmed using some crops and weeds.

Antifungal Agents↗
PubMed2001

Contributions of the substrate-binding arginine residues to maleate-induced closure of the active site of Escherichia coli aspartate aminotransferase.

Crystallography shows that aspartate aminotransferase binds dicarboxylate substrate analogues by bonds to Arg292 and Arg386, respectively [Jager, J, Moser, M. Sauder, U. & Jansonius, J. N. (1994) J. Mol. Biol., 239, 285-305]. The contribution of each interaction to the conformational change that the enzyme undergoes when it binds ligands via these residues, is assessed by probing mutant forms of the enzyme lacking either or both arginines. The probes used are NaH(3)BCN which reduces the cofactor imine, the reactive substrate analogue, cysteine sulfinate and proteolysis by trypsin. The unreactive substrate analogue, maleate, is used to induce closure. Each single mutant reacted only 2.5-fold more slowly with NaH(3)BCN than the wild-type indicating that charge repulsion by the arginines contributes little to maintaining the open conformation. Maleate lowered the rate of reduction of the wild-type enzyme more than 300-fold but had little effect on the reaction of the mutant enzymes indicating that the ability of this dicarboxylate analogue to bridge the arginines precisely makes the major contribution to closure. The R292L mutant reacted 20 times more rapidly with cysteine sulfinate than R386L but 5 x 10(4) times more slowly than the wild-type enzyme, consistent with the proposal that enzyme's catalytic abilities are not developed unless closure is induced by bridging of the arginines. Proteolysis of the mutants with trypsin showed that, in the wild-type enzyme, the bonds most susceptible to trypsin are those contributed by Arg292 and Arg386. Proteolysis of the next most susceptible bond, at Arg25 in the double mutant, was protected by maleate demonstrating the presence of an additional site on the enzyme for binding dicarboxylates.

Amino Acid Sequence↗
PubMed2001

[CT-guided needle biopsy of the lung: factors affecting risk of complications].

PURPOSE: To analyze factors influencing the risk of complications associated with CT-guided percutaneous needle biopsy for lung lesions. MATERIALS AND METHODS: Sixty patients, aged 24-85 years (37 men and 23 women), underwent CT-guided needle biopsy. A definite diagnosis was made in 49 of 60 cases (81.7%), including 38 of 43 malignant lesions (88.4%) and 11 of 17 benign lesions (64.7%). Complications associated with biopsy were observed in 35 patients (58.3%). Major complications included pneumothorax (n = 26) and pulmonary hemorrhage (n = 20). Chest tube placement was needed in 5 (19.2%) of 26 pneumothorax cases (8.3% of all biopsies). RESULTS: The high frequency of pneumothorax (43.3%) in this series had several contributing factors, including the presence of pulmonary emphysema, lesion size, and traversal of aerated lung. Chest tube replacement was necessary more frequently in patients with pulmonary emphysema. The number of pleural passes, location of lesions, and size of needles were not correlated with the incidence of pneumothorax. CONCLUSION: The presence of pulmonary emphysema, lesion size, and traversal of aerated lung are the predominant risk factors for pneumothorax in patients with CT-guided lung biopsy.

Adult↗
PubMed2001

Effect of soymilk consumption on serum estrogen and androgen concentrations in Japanese men.

Soy consumption has been associated with a reduced risk of prostate cancer. The mechanism for this association may involve the effect of soy on the endocrine system. We conducted a randomized dietary intervention study to determine the effects of soy consumption on serum levels of steroid hormones in men. Thirty-five men were randomly assigned to either a soymilk-supplemented group or a control group. The men in the soy-supplemented group were asked to consume 400 ml of soymilk daily for 8 weeks. The men in the control group maintained their usual diet. Blood samples were obtained just before the initiation of the dietary period and thereafter every two weeks for 12 weeks. Changes in hormone concentrations were analyzed and compared between the two groups using the mixed linear regression model against weeks from the start of the dietary period. The mean (SD) soymilk intake estimated from dietary records during the dietary study period was 342.9 (SD, 74.2) ml in the soymilk-supplemented group. There was a significant difference between the two groups in terms of changes in serum estrone concentrations, which tended to decrease in the soy-supplemented group and increase in the control group over time. None of the other hormones measured (estradiol, total and free-testosterone, or sex hormone-binding globulin) showed any statistical difference between the two groups in terms of patterns of change. The results of the study indicate that soymilk consumption may modify circulating estrone concentrations in men.

Adult↗
PubMed2001

[Usefulness of multiphase helical CT in the diagnosis of pituitary microadenoma].

The purpose of this study was to determine the value of multiphase helical CT (MHCT) in the diagnosis of pituitary microadenoma. Twenty-two patients with clinically suspected microadenoma were examined. Coronal pre-contrast CT was initially carried out. Three series of helical scanning using 1-mm collimation, 1-mm/s table speed, and 1-mm interval reconstruction covering the entire pituitary gland were performed with an intravenous injection of contrast medium. Immediately after MHCT, delayed CECT was performed. Twenty microadenomas (3-10 mm, mean: 5.5 mm) were surgically confirmed. MHCT could depict all 20 tumors, while pre-contrast CT and delayed CECT showed 4 and 12 of 20 tumors, respectively. MHCT was useful in the diagnosis of pituitary microadenoma owing to its high spatial resolution and extensive coverage.

Adenoma↗
PubMed2001

Coexpression of inducible nitric oxide synthase and COX-2 in hepatocellular carcinoma and surrounding liver: possible involvement of COX-2 in the angiogenesis of hepatitis C virus-positive cases.

Expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) has been reported to be responsible for enhanced tumor growth and angiogenesis in various tumors. However, the relationships between tumor vascularity and COX-2 and iNOS expression have not been evaluated in hepatocellular carcinoma (HCC). In this study, we examined the expression of iNOS and COX-2 and microvessel density (MVD) by immunohistochemical staining in 100 tissue sections collected from HCC patients. iNOS expression was significantly higher in hepatitis C virus (HCV)-positive HCCs (P = 0.011). COX-2 expression was significantly correlated with iNOS expression (P = 0.046) and tumor MVD (P = 0.011) in HCV-positive HCCS: iNOS expression was neither correlated with MVD nor had any influence on patient survival; however, combined negative expression of iNOS and COX-2 had a significant impact on patient survival (P = 0.041 and 0.018, log-rank test for overall and recurrence-free survival rate, respectively). The present findings suggest that combined expression of iNOS and COX-2 may play an important role in prognosis of HCV-positive HCC patients and that this could be partially attributable to modulation of angiogenesis by COX-2.

Adult↗