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Biomedical subjects

M Yoshikawa

Publications and source records attributed to M Yoshikawa.

At least 55 records · Page 3Linked to original sources
PubMed2001

Hepatoprotective constituents from zedoariae rhizoma: absolute stereostructures of three new carabrane-type sesquiterpenes, curcumenolactones A, B, and C.

New carabrane-type sesquiterpene lactones, curcumenolactones A, B, and C, were isolated from the 80% aqueous acetone extract of Zedoariae Rhizoma (Zingiberaceae), together with 41 sesquiterpenes and two diarylheptanoids. The absolute stereostructures of curcumenolactones A, B, and C were determined on the basis of physicochemical evidence, which included nuclear Overhauser effect (NOE) and circular dichroic (CD) spectroscopic analyses. Curcumenone, a principal carabrane-type sesquiterpene from Zedoariae Rhizoma, was found to show potent protective effect on D-galactosamine/lipopolysaccharide-induced acute liver injury in mice. In addition, curcumenolactones A and B and the other constituents showed protective effect on D-galactosamine-induced cytotoxicity in primary cultured rat hepatocytes.

Animals↗
PubMed2001

Dimeric sesquiterpene thioalkaloids with potent immunosuppressive activity from the rhizome of Nuphar pumilum: structural requirements of nuphar alkaloids for immunosuppressive activity.

Potent immunosuppressive dimeric sesquiterpene thioalkaloids, 6-hydroxythiobinupharidine, 6,6'-dihydroxythiobinupharidine, 6-hydroxythionuphlutine B and 6'-hydroxythionuphlutine B, were isolated from the rhizome of Nuphar pumilum together with five inactive quinolizidine alkaloids, neothiobinupharidine, nupharidine, deoxynupharidine, 7-epideoxynupharidine and nupharolutine. These dimeric sesquiterpene thioalkaloids were found to significantly inhibit anti-sheep erythrocyte plaque forming cell formation in mouse splenocytes at 1 microM. At this concentration. 6-hydroxythiobinupharidine, 6-hydroxythionuphlutine B and 6'-hydroxythionuphlutine B did not show cytotoxic effects to mouse splenocytes, and 6,6'-dihydroxythiobinupharidine also showed only minor or minimal cytotoxicity. By comparison of the inhibitory activity of several Nuphar alkaloids on anti-sheep erythrocyte plaque forming cell formation, some structural requirements of Nuphar alkaloids for immunosuppressive activity were obtained. Namely, the 6- or 6'-hydroxyl group at the quinolizidine ring of dimeric sesquiterpene thioalkaloids is essential for the immunosuppressive effect. The number of hydroxyl groups appears to be related to the cytotoxicity, and the influence on splenocytes is greater with increasing numbers of hydroxyl groups.

Alkaloids↗
PubMed2001

Structures of withanosides I, II, III, IV, V, VI, and VII, new withanolide glycosides, from the roots of Indian Withania somnifera DUNAL. and inhibitory activity for tachyphylaxis to clonidine in isolated guinea-pig ileum.

Seven new withanolide glycosides called withanosides I, II, III, IV, V, VI, and VII were isolated from an Indian natural medicine, Ashwagandha, the roots of Indian Withania somnifera DUNAL. (Solanaceae), together with four known compounds, withaferin A, 5 alpha,20 alpha(F)(R)-dihydroxy-6 alpha,7 alpha-epoxy-1-oxowitha-2,24-dienolide, physagulin D, and coagulin Q. The structures of withanosides I, II, III, IV, V, VI, and VII were determined based on chemical and physicochemical evidence. Principal constituents, withanoside VI (10 and 30 microM) and withaferin A (10 microM), attenuated the tachyphylaxis to clonidine on electrically stimulated guinea-pig ileum in vitro.

Adrenergic alpha-Agonists↗
PubMed2001

Inhibitors from rhubarb on lipopolysaccharide-induced nitric oxide production in macrophages: structural requirements of stilbenes for the activity.

By bioassay-guided separation, three stilbenes (rhapontigenin, piceatannol, and resveratrol), two stilbene glucoside gallates (rhaponticin 2"-O-gallate and rhaponticin 6"-O-gallate), and a naphthalene glucoside (torachrysone 8-O-beta-D-glucopyranoside) with inhibitory activity against nitric oxide (NO) production in lipopolysaccharide-activated macrophages were isolated (IC(50)=11--69 microM). The oxygen functions (-OH, -OCH(3)) of stilbenes at the benzene ring were essential for the activity. The glucoside moiety reduced the activity, while the alpha,beta-double bond had no effect. Furthermore, the active stilbenes (rhapontigenin, piceatannol, and resveratrol) did not inhibit inducible NO synthase activity, but they inhibited nuclear factor-kappa B activation following expression of inducible NO synthase.

Lipopolysaccharides↗
PubMed2001

A technique of cervical aortic graft transplantation in mice.

A new method of mouse aortic graft transplantation into carotid artery was developed with cuff technique. By harvesting the descending aorta of the donor using a small Teflon cuff (external diameter 0.6 mm, internal diameter 0.4 mm) and super fine-tip forceps, and modifying the method of mouse heterotopic heart transplantation with cuff technique, donor descending aortic allografts could be interposed in the common carotid artery of recipient mice. Histological analysis demonstrated neither evidence of tissue damage nor intimal thickening in isograft implanted over 100 days. We strongly recommend that this new model of aortic transplantation in mice is a simple and useful technique for vascular transplantation research.

Animals↗
PubMed2001

Novel quantitative reverse-transcribed polymerase chain reaction of mu opioid receptor mRNA level.

Reverse-transcribed polymerase chain reaction (RT-PCR) can quantify gene transcripts at low levels and in small samples. Semi-quantitative and quantitative RT-PCR has significant advantages over traditional RNA assays, such as Northern blotting and ribonuclease protection assay. However, owing to the exponential nature of PCR, considerable effort is required to verify linearity of the reaction. Thus, care must be taken to detect small but physiologically relevant changes in gene expression. Using a rapid and highly sensitive RT-PCR method, TaqMan real-time RT-PCR, we determined agonist-induced changes in rat mu opioid receptor (MOR) mRNA levels in cultured cells and compared our results with those obtained by radiolabeled quantitative RT-PCR, which is also highly sensitive but much more time-consuming than TaqMan RT-PCR. Both methods showed up-regulation of agonist-induced MOR. TaqMan RT-PCR showed a similar sensitivity to radiolabeled quantitative RT-PCR and is suitable for the measurement of large numbers of samples. Moreover, no need for radiolabeled compounds is also an advantage of TaqMan PCR. This protocol will probably be useful for quantifying MOR in animal and human tissues.

Analgesics, Opioid↗
PubMed2001

Molecularly imprinted polymeric membranes.

Molecularly imprinted polymeric membranes have been emerged since 1990. Among various kinds of molecular imprinting studies, the application of molecular imprinting to membrane separation is still a novel investigation. In the present review paper, molecularly imprinted polymeric membranes are summarized and examined. The application of molecular imprinting to membrane separation shortly leads to high performance separation membranes.

Membranes, Artificial↗
PubMed2001

Relationship between enantioselectivity of alternative molecularly imprinted polymeric membranes and species of amino acid residues composing chiral recognition sites.

Molecularly imprinted polymeric membranes with tetrapeptide residue H-Asp(OcHex)-Asp(OcHex)-Asp(OcHex)-Asp(OcHex)-CH2- (DDDD) or H-Glu(OBzl)-Glu(OBzl)-Glu(OBzl)-Glu(OBzl)-CH2- (EEEE) were prepared during membrane preparation (casting) processing in the presence of print molecules. The Boc-L-Trp imprinted polymeric membranes thus obtained showed adsorption selectivity toward Ac-L-Trp from its racemic mixtures. From adsorption isotherms of Ac-Trp, the chiral recognition site, that had been formed by the presence of print molecules in the membrane preparation process, exclusively recognized Ac-L-Trp that possessed the same configuration of the print molecule. The affinity constants between chiral recognition sites in the membrane and Ac-L-Trp was determined to be 1.00 x 10(4) mol(-1) dm3 and 1.08 x 10(4) mol(-1) dm3 for the DDDD and EEEE membranes, respectively. Enantioselective electrodialysis could be attained by applying an optimum potential difference to give permselectivity, with a value close to its adsorption selectivity.

Amino Acids↗
PubMed2001

Novel polymeric membranes having chiral recognition sites converted from tripeptide derivatives.

Six kinds of tripeptide derivative consisting of L-glutamic acid gamma-benzyl ester [Glu(OBzl)] (E) and L-phenylalanine (Phe) (F), i.e. EEF, EFE, FEE, FEF, FFE and FFF, were converted into chiral recognition sites by adopting Boc-L-Trp as a print molecule. The formed chiral recognition sites discriminated between Ac-L-Trp and the corresponding D-isomer, and the L-isomer was incorporated into the membrane in preference to the D-isomer. The affinity constants between the recognition site formed in each membrane and Ac-L-Trp were determined to be 9.6 x 10(3) to 8.4 x 10(3) mol-1 dm3. The affinity constant depends on both the tripeptide sequence and the amino acid residue content. Tripeptide derivatives containing more glutamic acid derivative residues or glutamic acid derivative as an amino-terminal residue show higher affinity constants.

Journal Article↗
PubMed2001

Development of the Baylor Gyro permanently implantable centrifugal blood pump as a biventricular assist device.

The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction phenomenon was not observed except for 1 case. There was no deterioration regarding visceral organ function, and pulmonary function was maintained within normal range except for 1 case. Even though the experimental animal survived up to 45 days with the flexible inflow conduit, an increase in power consumption due to thrombus formation behind the impeller became a problem. Lower rotational speed, which was probably produced by the effectiveness of the flexible inflow conduit, was speculated to be one of the reasons. And the minimum range of rotational speed was 1,950 rpm in these 6 BVAD cases and the previous 3 cases of LVAD. In conclusion, 6 cases of BVAD implantation were performed as in vivo animal studies and were observed up to 45 days. The flexible inflow conduit was applied in 4 of 6 cases, and it was effective in avoiding a suction phenomenon. The proper rotational speed of the Gyro PI 700 pump was detected from the viewpoint of antithrombogenicity, which is more than 1,950 rpm.

Animals↗
PubMed2001

Leptin augments inflammatory and profibrogenic responses in the murine liver induced by hepatotoxic chemicals.

Lines of evidence suggested a possible link between leptin and hepatic fibrosis; however, whether leptin modulates the fibrogenesis in the liver remains unclear. The purpose of this study, therefore, was to evaluate the effect of leptin on inflammatory and profibrogenic responses in the liver caused by hepatotoxic chemicals. Male C57Bl/6 mice were given carbon tetrachloride (CCl(4)) (0.1 microL/g body weight [BW], intraperitoneally [IP]) and/or recombinant murine leptin (1 microg/g BW, IP) simultaneously, and sacrificed up to 72 hours later. Further, some mice were given thioacetamide (TAA; 200 microg/g BW, IP) and leptin 3 times per week for 4 weeks to evaluate the effect of leptin on chronic fibrogenic responses. A simultaneous injection of leptin enhanced acute CCl(4)-induced necroinflammatory and subsequent fibrotic changes in the hepatic lobules. The steady-state messenger RNA (mRNA) levels of alpha1(I) procollagen and heat shock protein 47 (HSP47) in the liver were potentiated when leptin was injected together with CCl(4). Expression of alpha smooth muscle actin (alpha-SMA) in the liver after CCl(4) treatment was also augmented markedly in combination with leptin. Further, leptin increased transforming growth factor beta1 (TGF-beta1) mRNA in the liver 24 hours after acute CCl(4) about 4-fold higher than CCl(4) alone. Moreover, leptin enhanced hepatic fibrosis and induction of alpha1(I) procollagen mRNA caused by chronic TAA administration. Collectively, these findings indicated that leptin augments both inflammatory and profibrogenic responses in the liver caused by hepatotoxic chemicals. It is postulated that the increase in systemic leptin levels enhances up-regulation of TGF-beta1, leading to activation of stellate cells, thereby augmenting the fibrogenic response in the liver.

Actins↗
PubMed2001

The effect of nutritional status on morbidity in COPD patients undergoing bilateral lung reduction surgery.

BACKGROUND: Although candidates for lung reduction surgery (LRS) include malnourished patients with severe chronic obstructive pulmonary disease (COPD), the impact of preoperative nutritional status on surgical outcome has not been clearly elucidated. METHODS: We investigated the relationship between preoperative nutritional status and postoperative morbidity in 23 consecutive patients undergoing LRS. The percentage of ideal body weight (%IBW) and body mass index (BMI) were calculated, and fat-free mass (FFM) and fat mass (FM) were measured using a bioelectrical impedance analyzer. FFM and FM were expressed as height-normalized indices, FFM index [FFM (kg)/height (m)(2), or FFMI] and FM index [FM (kg)/height (m)(2), or FMI]. Serum levels of total protein and albumin were also determined. RESULTS: 8 patients had major complications. Preoperative %IBW and FFMI were significantly lower among patients with major complications, while no significant differences were observed in pulmonary function, FMI or serum protein. The complication rate was significantly higher among patients with low FFMI (FFMI < or = 16) but not with low %IBW or BMI. CONCLUSION: These results suggest that FFM depletion is an excellent predictor of unacceptable postoperative complication following LRS.

Aged↗
PubMed2001

Clinical studies of enteritis caused by methicillin-resistant Staphylococcus aureus.

OBJECTIVE: To study the clinical features of methicillin-resistant Staphylococcus aureus (MRSA) enteritis in our surgical ward. DESIGN: Retrospective study. SETTING: Teaching hospital, Japan. SUBJECTS: 16 men and 1 woman who developed MRSA enteritis from January 1995 to October 1999. MAIN OUTCOME MEASURES: Causes and treatments. RESULTS: The underlying diseases were as follows: gastric cancer (n = 13), colorectal cancer (n = 2), recurrent cancer (n = 1) and bowel obstruction following gastrectomy (n = 1). 16 patients were operated on. Two cases were treated with histamine H2 receptor blockers. The mean age of patients was 65 years (range 50-80). In 13 cases MRSA enteritis developed within 6 days of operation. 10 strains of MRSA were isolated from stools, 8 from gastric juice, and 3 from intra-abdominal exudate. 10 patients were treated with vancomycin given through a nasogastric tube and 2 through a nasogastric tube and by drip intravenous infusion. 15 patients survived and 2 died. CONCLUSIONS: Patients who are given broad-spectrum antibiotics and whose gastric secretion is reduced are at high risk of MRSA enteritis. In the surgical ward, early diagnosis, treatment, and isolation are essential for patients with MRSA enteritis.

Aged↗
PubMed2001

Clinical characteristics of acute hemorrhagic rectal ulcer.

BACKGROUND: Acute hemorrhagic rectal ulcer (AHRU) occurs suddenly with painless, massive, fresh rectal bleeding in elderly, bed-ridden patients who have a serious primary disease. There have been several reports on AHRU in Japan, but in Western countries, there have been none. We examined the clinical characteristics of four cases, and we report on AHRU in Western countries. STUDY: The medical records and endoscopic findings in four patients with AHRU seen during a 3-year period were reviewed. The diagnosis of AHRU was established by clinical symptoms, endoscopic examination, and other methods. RESULTS: All of the patients were elderly and bed-ridden and all had sudden onset of massive, fresh rectal bleeding without pain. Sigmoidoscopic examination of all patients showed a shallow or irregular bleeding ulcer in the lower rectum. In three cases, the clinical course was uneventful. In the other case, massive, fresh rectal bleeding recurred but transanal ligation was effective. CONCLUSIONS: When painless, massive, fresh rectal bleeding occurs in elderly and bed-ridden patients, it is important to carefully examine the lower rectum, as there is a strong possibility of AHRU.

Aged↗
PubMed2001

Reconstitution and purification of cytolethal distending toxin of Actinobacillus actinomycetemcomitans.

Cytolethal distending toxin (CDT) has been found in various pathogenic bacterial species and causes a cell distending and a G2 arrest against eukaryotic cells. All the cdtABC genes, which encode CDT, are known to be required for the CDT activities although the CDT holotoxin structure has not been elucidated. We cloned the cdtABC genes of Actinobacillus actinomycetemcomitans and constructed an Escherichia coli expression system for them. We found that crude extracts from six deletion mutants (delta cdtA, delta cdtB, delta cdtC, delta cdtBC, delta cdtAC, and delta cdtAB) of recombinant E. coli, which showed very weak or no detectable CDT activities, restored the CDT activities when pre-mixing and pre-incubation of them were performed in combinations to contain all the CdtA, CdtB, and CdtC proteins. These results indicate that all the Cdt proteins are required for the CDT activities. We also found that the chimera CdtB protein, CdtB-intein-CBD (chitin binding domain) like CdtB protein itself assembled with CdtA and CdtC. The reconstituted CDT containing the chimera CdtB protein was specifically extracted by chitin beads and the only CDT portion was isolated from the chitin beads by a cleavage reaction of the intein. The purified reconstituted-CDT was found to consist of CdtA, CdtB, and CdtC proteins, and showed appreciable CDT activities, indicating that the CDT holotoxin structure is the CdtABC complex. To our knowledge, this is the first report succeeded in complete purification of an active CDT and may offer useful tools for elucidation of the toxic mechanism of CDT.

Aggregatibacter actinomycetemcomitans↗
PubMed2001

Histopathological studies on virulence of dipeptidyl aminopeptidase IV (DPPIV) of Porphyromonas gingivalis in a mouse abscess model: use of a DPPIV-deficient mutant.

To elucidate the role of dipeptidyl aminopeptidase IV (DPPIV) in the virulence of Porphyromonas gingivalis, mice were infected with either a wild-type strain or a DPPIV-deficient mutant using an abscess model. Histopathological analysis of the resulting lesions indicated that DPPIV participates in virulence through the destruction of connective tissue and the less effective mobilization of inflammatory cells.

Abscess↗