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Biomedical subjects

K Yazawa

Publications and source records attributed to K Yazawa.

At least 73 records · Page 4Linked to original sources
PubMed1998

Modulation of eosinophil chemotactic activities to leukotriene B4 by n-3 polyunsaturated fatty acids.

Eosinophil accumulation induced by leukotriene B4 appears to be involved in the pathogenesis of allergic diseases. We evaluated the effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on chemotaxis to leukotriene B4 in guinea pig peritoneal eosinophils. Guinea pigs that were sensitized to polymyxin B were administered an intraperitoneal injection of polymyxin B (1 mg/animal) alone or combined with DHA (15 or 50 mg/kg, i.p.), EPA (50 or 100 mg/kg, i.p.), or with linoleic acid (LA) (100 mg/kg, i.p.). Forty hours later, eosinophils were obtained from the intraperitoneal lavage fluid and purified. The chemotactic and chemokinetic responses of eosinophils to leukotriene B4 were measured using a 96-well microchemotaxis chamber. DHA significantly decreased the chemotactic and chemokinetic responses of eosinophils in a dose-dependent fashion. A higher dose of EPA also significantly inhibited both of those responses, whereas LA had no effect. Our results suggested a possible mechanism for the improvement of allergic diseases by dietary supplementation with n-3 PUFA.

Animals↗
PubMed1998

Colorimetric MTT assessment of antifungal activity of D0870 against fluconazole-resistant Candida albicans.

The in vitro antifungal activity of D0870 against eight isolates of fluconazole-resistant Candida albicans was compared with that of itraconazole, ketoconazole and miconazole. The colorimetric MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] assay was used to assess the antifungal activities. The 50% minimum inhibitory concentration (MIC50) of D0870 was below 0.031 microgram ml-1 for seven isolates and 0.25 microgram ml-1 for one isolate. The activity of D0870 was superior to that of the other azoles. Ketoconazole was the most effective azole next to D0870. Therefore, the new bis-triazole, D0870, is expected to be promising for the therapy of fluconazole-resistant candidosis. The present data also confirmed that the MTT assay may be useful for evaluation of resistance and detection of resistant C. albicans.

Antifungal Agents↗
PubMed1998

Malignant neoplasm in kidney transplantation.

BACKGROUND: The kidney recipient is at a higher risk for cancer than is the general population, although the incidence of neoplasms in general is considered lower in Japan than in Western countries. The cause of this increased risk associated with either transplantation or geography has not yet been established. METHOD: The incidences and sites of malignant neoplasms were analyzed in 285 kidney recipients, who had been followed up for 3007 patient-years. The relationship between immunosuppressive states, the numbers of CD4-positive T lymphocytes, and the presence of malignant neoplasms was studied retrospectively. RESULTS: Eighteen malignant neoplasms were found in 17 of the 285 patients (6%). The malignancies developed in these patients an average of++ 1 26.5 months after transplantation. The incidence was only 3.9% at 10 years, increasing to 13.9% at 20 years. No difference in the time-course incidence was found between azathioprine-based and cyclosporin-based immunosuppressive regimens. The malignancies developed in the digestive organs in more than half of the patients, and were mainly in the liver, colon and rectum, and stomach, with a relatively low incidence of skin cancer and lymphoma. There was only one case of Epstein-Barr virus genome found in 5 specimens that were tested. Concerning the immunosuppressive state, CD4-positive T lymphocyte counts were not related directly with malignancies in our series. CONCLUSION: The cumulative incidence of malignancy increased markedly in the second posttransplant decade. The site of cancers in kidney recipients mirrors that of general Japanese malignancies. Our results revealed neither the cause nor predictor for malignancies in kidney transplant patients.

Adolescent↗
PubMed1998

Synchronous gastric tumors associated with esophageal cancer: a retrospective study of twenty-four patients.

OBJECTIVES: Synchronous gastric tumors (including benign and secondary tumors) associated with esophageal cancer present diagnostic and therapeutic issues. We investigated this synchronous association, and retrospectively determined the frequency of the gastric tumors and the clinical characteristics. METHODS: In a series of 208 patients with esophageal cancer, we investigated the synchronous gastric tumors, as well as the frequency of association, clinicopathological characteristics, diagnosis, treatment, and the clinical outcome after surgery. RESULTS: Twenty-eight gastric tumors were found in 24 patients. Adenocarcinoma was most frequent. Most of these tumors were located at the upper or middle third of the stomach. Eight gastric tumors in six patients could not be detected preoperatively. Six of these tumors including a gastric remnant cancer were detected in the resected stomach, and two leiomyomas were detected during the operation. In one patient in which an endoscope could not pass through the esophagus, a leiomyoma was detected in the resected stomach. For the gastric cancers, total gastrectomy or proximal gastrectomy with lymph node dissections was performed. For the benign tumors, partial resection of the stomach was performed, and endoscopic resection was performed preoperatively for an adenoma. In both the postoperative hospital mortality rate and the survival rate after surgery, there were no significant differences between the patients with and without gastric tumors. CONCLUSIONS: Synchronous gastric tumors associated with esophageal cancer are not rare. When an endoscope cannot pass through the esophagus before surgery, other techniques must be performed to explore the stomach. For these patients, surgical treatment should be adapted positively.

Aged↗
PubMed1998

Genetic analysis of Histoplasma capsulatum strains isolated from clinical specimens in thailand by a PCR-based random amplified polymorphic DNA method.

Thirteen strains of Histoplasma capsulatum were isolated from clinical specimens, including those from AIDS patients, in Thailand. Random amplified polymorphic DNA (RAPD) analysis with three different PCR primers showed that the DNA fingerprint patterns of the Thai isolates were very similar to each other and homogeneous, with only one exceptional strain, although the patterns were clearly different from those of a reference North American strain with all primers tested. Although the difference in the DNA fingerprinting patterns was minor, Thai isolates could be classified into two to four groups. A common PCR band (about 700 bp) in the patterns of all H. capsulatum strains was extracted, and its DNA sequence was determined. A new PCR primer set for the identification of H. capsulatum species was developed based on this sequence information. This primer set was 100% successful in the identification of the reference strain as well as all Thai isolates. The results of specificity tests of the primer set for the identification of the fungus are also discussed.

AIDS-Related Opportunistic Infections↗
PubMed1998

Effects of dietary alpha-linolenic, eicosapentaenoic and docosahexaenoic acids on hepatic lipogenesis and beta-oxidation in rats.

The effects of dietary alpha-linolenic, eicosapentaenoic and docosahexaenoic acids on the enzyme activities related to hepatic lipogenesis and beta-oxidation were compared under constant polyunsaturated/monounsaturated/saturated fatty acids and n-6/n-3 ratios of dietary fats in rats. Dietary fat containing linoleic acid as the sole polyunsaturated fatty acid (PUFA) was also given as a control. The concentration of serum triglyceride and phospholipid in the three n-3 PUFA groups was lower than in the linoleic acid group. The hepatic triglyceride concentration was lower and the phospholipid concentration was higher in the three n-3 PUFA groups than in the linoleic acid group. Cytosolic fatty acid synthase (FAS) activity was lower in the n-3 PUFA groups than in the linoleic acid group, the reduction being more predominant in the eicosapentaenoic acid and docosahexaenoic acid groups than in the alpha-linolenic acid group. The cytosolic activities of the NADPH-generating enzymes, glucose-6-phosphate dehydrogenase (G6PDH) and the malic enzyme, were lower in the three n-3 PUFA groups. The activity of carnitine palmitoyltransferase (CPT) in mitochondria was higher only in the eicosapentaenoic acid group than in the other groups. The activity of Mg(2+)-dependent phosphatidate phosphohydrolase (PAP) in microsomes and cytosol was lower in the eicosapentaenoic and docosahexaenoic acid groups than in the linoleic acid group, while there was no effect of dietary fats on the activities of diacylglycerol acyltransferase (DGAT) and glycerol-3-phosphate acyltransferase (G3PAT) in microsomes. The CTP: phosphocholine cytidylyltransferase (CT) activity in the homogenate was lower in the n-3 PUFA groups, the reduction being more prominent in the eicosapentaenoic and docosahexaenoic acid groups than in the alpha-linolenic acid group. The choline kinase (CK) activity in cytosol was lower in the eicosapentaenoic acid group than in the linoleic acid group. These results showed that dietary alpha-linolenic, eicosapentaenoic and docosahexaenoic acids differently influenced hepatic lipogenesis and the partition of fatty acid into oxidation or glycerolipid synthesis.

Animals↗
PubMed1998

[Evaluation of the E-test: comparison of E-test and microbroth dilution method in azole antifungal susceptibility test].

The susceptibilities of clinical isolates of Candida spp. to fluconazole (FLCZ), itraconazole (ITCZ) and ketoconazole (KCZ) were determined by a new method, E-test (AB BIODISK, Sweden) and compared with those obtained by the microbroth dilution method. The MIC values of the 3 azoles obtained by the two methods were, in general, in good agreement. While MICs of FLCZ and KCZ demonstrated higher essential agreement rates and better correlation by both methods, MIC values of ITCZ by the E-test had a tendency to be higher than those of the microbroth dilution method in azole resistant strains. Potential usability of E-test as a broth dilution method for susceptibility tests for clinically isolated Candida spp. including azole resistant strains was discussed.

Antifungal Agents↗
PubMed1998

Demethyl mutactimycins, new anthracycline antibiotics from Nocardia and Streptomyces strains.

New anthracycline antibiotics 3'-O-demethyl mutactimycin (3) and 4-O,3'-O-didemethyl mutactimycin (4) were isolated from two actinomycetes strains, Nocardia transvalensis and Streptomyces sp. GW 60/1571. The chemical structures were elucidated by mass spectrometry and NMR spectroscopy. Antibiotic 3 displayed moderate antimicrobial activity against Gram-positive bacteria and cytotoxicity against P388, L1210 and HeLa tumor cells (IC50; 9.6, >25 and 20 microg/ml, respectively).

Animals↗
PubMed1998

[Continuous intraportal chemotherapy for prevention of metachronous hepatic metastasis in colorectal cancer].

Fifty-five colorectal cancer patients who had continuous intraportal chemotherapy between 1990 and 1993 (treated group) and 130 colorectal cancer patients who did not have portal chemotherapy between 1982 and 1993 (untreated group) were studied to clarify the effects of continuous intraportal chemotherapy on the prognosis. After a catheter was placed in the portal vein through the right gastroepiploic vein at the time of radical operation, 10 mg of MMC was continuously infused for 4 hours at operation and 500 mg/day of 5-FU was continuously infused for 7 days postoperatively. The toxicities of this therapy were not serious. The five-year survival rate was 65.3% in the treated group and 65.6% in the untreated group. The five-year disease-free survival rate was 69.8% in the treated group and 58.6% in the untreated group, with no significant difference. In stage II patients, however, the five-year disease-free survival rate in the treated group was slightly higher than in the untreated group (90.0% vs 70.3%, p = 0.073), and the rate of hepatic recurrence in the treated group was significantly lower than in the untreated group. These results suggest that continuous intraportal chemotherapy may prevent metachronous hepatic metastases in stage II colorectal cancer patients.

Aged↗
PubMed1997

Inhibitory effects of oleic and docosahexaenoic acids on lung metastasis by colon-carcinoma-26 cells are associated with reduced matrix metalloproteinase-2 and -9 activities.

In order to determine the effects of single unsaturated fatty acids (UFAs) or combinations on establishment of lung metastatic colonies, UFAs were administered orally to CDF1 mice bearing s.c. implants of the highly metastatic colon carcinoma 26. Oleic acid (OA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) demonstrated significant inhibition. In the case of DHA, this inhibitory potential was markedly reduced by co-administration of linoleic acid (LA) or EPA. Furthermore, while tumor cells treated with DHA showed a very low potential for lung colony formation when injected i.v., this again being partially reversed by co-administration of EPA. UFAs were found to be well absorbed into tumor tissues after oral administration, causing marked changes in relative levels, the arachidonic acid (AA) content, in particular, being markedly decreased by treatment with DHA or EPA, but not with DHA plus EPA or with DHA plus LA. Investigation of the gelatinolytic activity of the 57-kDa and 92-kDa isoforms of type-IV collagenase (MMP-2 and MMP-9, respectively) showed a clear reduction in the former by treatment with OA, while DHA, but not DHA plus LA or EPA, caused a decrease in the 92-kDa isoform, which was well correlated with AA content in tumor tissues (r = 0.900, p < 0.001). These results suggest that inhibition of metastasis due to treatment with OA and DHA might be due to depressed type-IV collagenase activity.

Animals↗
PubMed1997

Decreased heart rate by acupuncture stimulation in humans via facilitation of cardiac vagal activity and suppression of cardiac sympathetic nerve.

The effect of acupuncture stimulation applied to a Ximen point (P4) of a forearm on heart rate was studied in healthy volunteer human subjects. Acupuncture stimulation decreased heart rate, or gave no significant response. The decreased response of heart rate following acupuncture was attenuated by administration of atropine and propranolol. Therefore, the acupuncture-induced response of decrease in heart rate was concluded to be a result of a reciprocal coordination of an increase in cardiac vagal activity and a decrease in cardiac sympathetic activity.

Adult↗
PubMed1997

Pharmacological targeting of long QT mutant sodium channels.

The congenital long QT syndrome (LQTS) is an inherited disorder characterized by a delay in cardiac cellular repolarization leading to cardiac arrhythmias and sudden death often in young people. One form of the disease (LQT3) involves mutations in the voltage-gated cardiac sodium channel. The potential for targeted suppression of the LQT defect was explored by heterologous expression of mutant channels in cultured human cells. Kinetic and steady state analysis revealed an enhanced apparent affinity for the predominantly charged, primary amine compound, mexiletine. The affinity of the mutant channels in the inactivated state was similar to the wild type (WT) channels (IC50 approximately 15-20 microM), but the late-opening channels were inhibited at significantly lower concentrations (IC50 = 2-3 microM) causing a preferential suppression of the late openings. The targeting of the defective behavior of the mutant channels has important implications for therapeutic intervention in this disease. The results provide insights for the selective suppression of the mutant phenotype by very low concentrations of drug and indicate that mexiletine equally suppresses the defect in all three known LQT3 mutants.

Anti-Arrhythmia Agents↗
PubMed1997

Adverse effects of intraportal chemotherapy on natural killer cell activity in colorectal cancer patients.

BACKGROUND: Adjuvant intraportal chemotherapy has been used with a view to prevent the development of metachronous hepatic metastases following curative resection for colorectal cancer. To evaluate the effects of this therapy on systemic antitumor immunological activity, 35 colorectal cancer patients who underwent curative resection were investigated. METHOD: Among them. 19 had adjuvant intraportal chemotherapy with mitomycin C and 5-fluorouracil (treated group) and 16 had no chemotherapy (untreated group). Natural killer (NK) cell activity, lymphocyte subpopulations, and immunosuppressive acidic protein (IAP) in the peripheral blood were measured serially before and after operation, and the values were compared between the two groups. RESULTS: The NK cell activity and the percentages of CD16 positive and CD56 positive cells were markedly reduced in the treated group postoperatively. Significant difference was also observed between the two groups on the 4th postoperative day in regard to NK cell activity and CD56 positive cells. CONCLUSIONS: Intraportal chemotherapy in our study reduced the NK cell activity and its population in the peripheral blood.

Aged↗
PubMed1997

Run-down of the cardiac Ca2+ channel: characterization and restoration of channel activity by cytoplasmic factors.

Possible mechanisms for run-down in the Ca2+ channel, such as proteolysis or dephosphorylation of the channel, were examined in guinea-pig ventricular myocytes. The Ca2+ channel current, recorded in inside-out patches using a pipette solution containing 50 mM Ba2+ and 3 microM Bay K 8644, ran down with a mean survival time of 2.35 min. The survival time was not significantly affected by adenosine triphosphate (ATP) (3 mM), 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid (BAPTA) (2 mM), isoprenaline (l-5 microM), phosphate (l20 mM) and leupeptin (l0 microM). Stimulation of guanosine triphosphate (GTP)-binding proteins was also ineffective. The catalytic subunit of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA, 0.5-2 microM) slightly and transiently increased channel activity, but had minimal effects on the channel when applied after complete run-down. On the other hand, cytoplasm from the heart, skeletal muscle, brain and liver, but not kidney, induced channel activity. There was a positive correlation between NPo (the product of the number of channels N and the open probability Po) value before run-down and that after the application of cytoplasm, suggesting that the activity of once-active channels was restored ba the exogenous cytoplasm. The potency of cytoplasm in tissues in inducing channel activity was not related to PKA activity nor to the number of dihydropyridine binding sites. These results suggest that the run-down of the cardiac Ca2+ channel is not mediated by dephosphorylation or proteolysis of the channel, but involves other factor(s), possibly interaction of the channel protein with a cytoplasmic regulatory protein.

Adenosine Triphosphate↗
PubMed1997

ATP regulates cardiac Ca2+ channel activity via a mechanism independent of protein phosphorylation.

The role of adenosine triphosphate (ATP) in the regulation of L-type Ca2+ channel activity was investigated in inside-out patches from guinea-pig ventricular cells, in which the Ca2+ channel activity had been reprimed by application of cytoplasm from bovine heart. Passing the cytoplasm through a diethylaminoethyl (DEAE)-sepharose column or heating at 60 degrees C for 20 min attenuated the induction Ca2+ channel activity to 6-13% of that in the preceding cell-attached patch. Addition of 10 mM MgATP to the cytoplasm greatly improved the potency of cytoplasm in restoring Ca2+ channel activity (to 83 +/- 22%, mean +/- SE). This effect of MgATP was also produced, although with lower potency, by K2ATP (61 +/- 20%) or 5'-adenylylimidodiphosphate (AMP-PNP, 39 +/- 7%), a non-hydrolyzable ATP analogue, suggesting that hydrolysis of ATP is not required for the stimulatory effect on channel activity. A non-specific protein kinase inhibitor H8 (50-100 microM) did not inhibit the effect of cytoplasm + MgATP on channel activity, suggesting the involvement of a pathway independent of phosphorylation. We conclude that ATP regulates Ca2+ channel activity in dual pathways: one with, and the other without, protein phosphorylation.

Adenosine Triphosphate↗
PubMed1997

Lipid and fatty acid compositions of a novel docosahexaenoic acid-producing marine bacterium.

An unidentified bacterial strain, SCRC-21406, isolated from the intestine of a marine fish, Glossanodon semifasciatus, produced docosahexaenoic acid at 23% (mol/mol) [= 28% (w/w)] of total fatty acids in a medium containing 0.5% (wt/vol) peptone and 0.1% (wt/vol) yeast extract at 12 degrees C under atmospheric pressure. The cell yield was 0.43 g/L. The major lipids of the strain were phosphatidylethanolamine and phophatidylglycerol. Docosahexaenoic acid was localized at the sn-2 positions of both phospholipids. The amounts of polyunsaturated fatty acids other than docosahexaenoic acid were extremely small [< 3% (mol/mol)]. Monounsaturated fatty acids of the cis-7, cis-9 and cis-11 types were detected.

Animals↗