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Biomedical subjects

S Sakai

Publications and source records attributed to S Sakai.

At least 109 records · Page 6Linked to original sources
PubMed2000

Nutritional assessments of 3-day dietary records in National Institute for Longevity Sciences--Longitudinal Study of Aging (NILS-LSA).

Food and nutrient intake of NILS-LSA participants 40 to 79 years of age were assessed through 3-day weighed dietary records by gender and age. The results were as follows. The intake of fats and oils, meats and beverages tended to decrease, but fruits increased with age in both males and females. Regarding nutrient intake, energy, protein, fat, and cholesterol showed a decrease as individuals aged. The nutrient intake in the 70 to 79 yr group was significantly lower than other age groups of both genders. The total dietary fiber and vitamin C intake increased. Salt intake exceeded 10 g/day in every group. The percentage of energy from fat to total energy was higher than 25% in most age groups. The proportion of fatty acids was almost appropriate in all groups.

Adult↗
PubMed2000

[Analysis of the contractions evoked by sympathetic nerve stimulation, and thermal effect on the guinea-pig vas deferens--study as a model for the thermotherapy of benign prostatic hyperplasia].

BACKGROUND: The present study was designed to investigate the mechanism of thermotherapy on benign prostatic hyperplasia (BPH), using the guinea-pig vas deferens as a model for BPH. The components of contractions elicited by electrical field stimulation and nicotine were analyzed, and the thermal effect on the vas deferens was examined. METHODS: The vas deferens was dissected, suspended vertically through two silver ring electrodes, and attached to an isometric transducer. The electrical stimulation of 10 constant current pulses (10 mA) with 0.3 msec in duration of 5, 10, and 40 Hz was achieved under air-gap condition. Drugs were added directly to a 5 ml Magnus tube containing Tyrode solution (36 degrees C) gassed with a 95% O2-5% CO2 mixture. The components of contractions evoked by electrical stimulation and nicotine were investigated by tetrodotoxin (TTX), and blocking agents of alpha 1-adrenoceptors and/or purinoceptors. Thermal effect on electrically evoked contractions was examined at incubation temperature of 25 degrees C (control), 43 degrees C, 45 degrees C, 46 degrees C and 47 degrees C for 1 hour. RESULTS: Nicotine (200 microM) elicited biphasic contractions, which were triggered by corelease of noradrenaline (NA) and ATP (N-ATP) from sympathetic nerve terminals by activation of prejunctional nicotine receptors. NA and N-ATP caused the corresponding contractions, alpha 1 and N-ATP components, respectively. Combined application of prazosin (1 microM) and suramin (50 microM) abolished these contractions. Activation of post-junctional alpha 1-adrenoceptors by NA caused release of ATP from muscle cells to produce the contraction (alpha 1-ATP component), which was sensitive to both suramin and prazosin. N-ATP and alpha 1 components attributed to fast and slow part of the contraction, respectively. Electrical field stimulation caused biphasic contractions which consisted of both neurogenic (TTX-sensitive) and non-neurogenic (TTX-insensitive) components. An increase in stimulation frequency (5 to 40 Hz) increased the neurogenic components, which contained alpha 1 and N-ATP components, as well as the case of nicotine. The non-neurogenic components consisted of alpha 1-ATP, muscle-derived ATP (m-ATP) and unknown substance 'X' components. Nifedipine (10 microM). L-type Ca2+ channel blocker, markedly reduced the contractions induced by bath applied phenylephrine (alpha 1-agonist, 100 microM) but only partially blocked the contractions produced by bath applied ATP (500 microM). The contractile force in amplitude and neurogenic components induced by electrical field stimulation did not change at 43 degrees C, but both declined significantly above 45 degrees C. The neurogenic components at 45 degrees C and 46 degrees C were suppressed to 22 +/- 6% and 14 +/- 3% (mean +/- SD) of control, respectively. All the contractile responses were abolished at 47 degrees C. CONCLUSION: The contractions of the guinea-pig vas deferens evoked by electrical field stimulation consisted of alpha 1, N-ATP, alpha 1-ATP, m-ATP and X components. Sympathetic nerve fibers in the muscles were completely inactivated by thermal exposure at 47 degrees C for 1 hour. The results suggest that the minimal temperature for thermotherapy of BPH should be 47 degrees C.

Adenosine Triphosphate↗
PubMed2000

Artocarpus (Moraceae)-gall midge pollination mutualism mediated by a male-flower parasitic fungus.

A previously undescribed pollination system involving a monoecious tree species, Artocarpus integer (Moraceae), pollinator gall midges, and fungi is reported from a mixed dipterocarp forest in Sarawak, Borneo. The fungus Choanephora sp. (Choanephoraceae, Mucorales, Zygomycetes) infects male inflorescences of A. integer, and gall midges (Contarinia spp., Cecidomyiinae, Diptera) feed on the fungal mycelia and oviposit on the inflorescence. Their larvae also feed on the mycelia and pupate in the inflorescence. The gall midges are also attracted by female inflorescences lacking mycelia, probably due to a floral fragrance similar to that of male inflorescences. Because of the sticky pollen, dominance of Contarinia spp. in flower visitors, and pollen load observed on Contarinia spp. collected on both male and female inflorescences, Artocarpus integer is thought to be pollinated by the gall midges. Although several pathogenic fungi have been reported to have interactions with pollinators, this is the first report on a pollination mutualism in which a fungus plays an indispensable role. The pollination system described here suggests that we should be more aware of the roles fungi can play in pollinations.

Journal Article↗
PubMed2000

[Preventive effect of chlormadinone acetate on flare-up phenomenon in advanced prostate cancer administered with a luteinizing hormone-releasing hormone analogue].

To investigate whether chlormadinone acetate (CMA) could prevent the flare-up phenomenon induced by a luteinizing hormone-releasing hormone analogue (LH-RHa), we treated 4 cases of stage C and 17 cases of stage D prostate cancer with CMA for 4 weeks and CMA plus monthly injection of LH-RHa for following 24 weeks. Serum LH, testosterone, and prostate-specific antigen (PSA) levels were closely monitored before and 3 days, 1-, 2-, and 4-weeks after LH-RHa injection. Subjective and objective responses were also investigated. Serum LH and testosterone levels significantly elevated 3 days after the initial injection of LH-RHa. However, they resumed 1 week after LH-RHa injection with fluctuation under the normal range. Out of 21 cases, 3 cases (14%) consisting of 2 poorly and 1 moderately differentiated adenocarcinoma showed increased serum PSA levels 1 week after LH-RHa injection in spite of suppressed serum testosterone levels. The objective response of these 2 poorly differentiated cases was progressive disease at 24 weeks. No cases indicated worsening of clinical symptoms concerning flare-up phenomenon. CMA seemed to be capable of preventing flare-up phenomenon in advanced prostate cancer.

Acute-Phase Reaction↗
PubMed2000

Quantitative analysis of technegas SPECT: evaluation of regional severity of emphysema.

UNLABELLED: The purpose of this study was to quantify the regional severity of emphysema by 3-dimensional fractal analysis of technegas (99mTc-carbon particle radioaerosol) SPECT images. METHODS: Technegas SPECT was performed on 22 patients with emphysema. The lungs were delineated using 4 cutoff levels (15%, 20%, 25%, and 30% of the maximal pixel radioactivity), and the total number of pixels was measured in the areas surrounded by the contours obtained with each cutoff level. We calculated fractal dimensions from the relationship between the total number of pixels and cutoff levels transformed into logarithms. Fractal dimension for total or regional lung was defined as the severity of emphysema. RESULTS: Total lung fractal dimension (T-FD), upper lung fractal dimension (U-FD), and lower lung fractal dimension (L-FD) for patients with emphysema were 1.84 +/- 0.46 (mean +/-SD), 2.22 +/- 0.61, and 1.77 +/- 0.49, respectively. U-FD was significantly greater than was L-FD. Patients with the ratio of U-FD to L-FD of <1.16 had a significantly greater percentage forced vital capacity (FVC) than did patients with the ratio of >1.16. Patients with an L-FD of <1.8 had a significantly greater forced expiratory volume in 1 s (FEV1)/FVC than did patients with that of >1.8. No significant difference was found between patient groups stratified by U-FD. CONCLUSION: The regional severity of emphysema was well shown by these fractal dimensions.

Female↗
PubMed2000

[A case of lung tumorlets with pulmonary carcinoid].

It has been postulated that differential pathological diagnosis of lung tumorlet from pulmonary carcinoid is very important to decide the therapeutic strategy, because both of them are pathologically consisted of similar type of cells originated from same cells. At the present, although lung tumorlet is considered to be a hyperplastic lesion of Kultschitzky cells which is located in the epithelial cell of the bronchial mucosa by stimuli such as hypoxia and inflammation, but it occasionally recognized in the normal lung and the concept that it is a subtype of carcnoid is also undeniable. In this paper, a case of lung tumorlet with minute pulmonary carcinoid suggesting a subtype of carcinoid operated upon in our department is presented. Although simple pulmonary resection is a method of choice for pulmonary carcinoid, but it is still controversial as to therapeutic strategy for the lung tumorlet, because it is a benign entity and not tumorous lesion. However pulmonary resection with a close subsequent followed-up study must be a best method of choice for the case with lung tumorlet includes a minute lesion of carcinoid seen in this particular case.

Carcinoid Tumor↗
PubMed2000

Multi-institutional validation study of carboplatin dosing formula using adjusted serum creatinine level.

Creatinine clearance (Ccr) is widely used as a practical substitute for glomerular filtration rate (GFR) in the Calvert formula: carboplatin dose (mg) = target area under the concentration versus time curve (AUC, mg ml(-1) min) x [GFR (ml min(-1)) + 25]. However, it causes systematic overdosing when the creatinine levels are measured by an enzymatic peroxidase-antiperoxidase method (PAP-Cr). We previously suggested an amended dosing formula to adjust this overdosing: carboplatin dose (mg) = AUC (mg ml(-1) min) x [adjusted Ccr (ml min(-1)) + 25], where the Ccr was adjusted by adding 0.2 (mg dl(-1)) to serum PAP-Cr. In this study, we prospectively validated this formula in 55 patients from six institutions. Target AUC ranged from 3 to 7 mg ml(-1) min, and Ccr was measured by 24-h urine collection. Estimation of carboplatin clearance with the amended formula was unbiased [mean prediction error (MPE) +/- SE = 2.9 +/- 3.4%] and acceptably precise [root mean squared error, (RMSE) = 24.7%], whereas the Calvert formula using non-adjusted Ccr overpredicted carboplatin clearance systematically (MPE +/- SE = 24.9 +/- 4.9% and RMSE = 36.1%). The improvement in the bias and precision of the estimation was seen in all of the participating institutions as shown by decrease in the absolute value of MPE and RMSE for each institution. The Chatelut formula also highly overestimated carboplatin clearance when PAP-Cr was used, but the adjustment of PAP-Cr yielded a decrease in MPE by 30.4% and in RMSE by 21.3%. These results confirmed the necessity of adjusting the serum PAP-Cr in carboplatin dosing formulas.

Adult↗
PubMed2000

[A case of traumatic priapism].

We report a case of high flow priapism secondary to arteriovenous fistula produced by perineal trauma in a 43-year-old patient. Diagnosis was based on the result of gasometry in cavernous blood and color doppler sonography. Superselective embolization of the deep artery of the penis was performed with good results. After 6 months of treatment, erection and sexual function were normal. Our case demonstrates that this procedure is a safe and effective therapy for high flow priapism.

Adult↗
PubMed1999

Identification of a functional transcriptional factor AP-1 site in the sheep interferon tau gene that mediates a response to PMA in JEG3 cells.

To examine regulatory mechanisms of sheep interferon tau (oIFNtau) gene expression, potential enhancer/silencer elements of the oIFNtau gene were examined using a transient transfection system with oIFNtau gene-chloramphenicol acetyltransferase (oIFNtau-CAT) reporter constructs in human choriocarcinoma cells, JEG3. Experiments with 5'-deletion constructs revealed that the upstream regions from bases -654 to -607 and from bases -606 to -555 were essential for oIFNtau gene expression. In a heterologous transcriptional system in which the upstream regions of oIFNtau were inserted in front of simian virus 40 (SV40) promoter, the regions between bases -654 and -555 were determined as being the enhancer region required for oIFNtau-SV40-CAT transactivation. A subsequent study with the oIFNtau-CAT constructs lacking the upstream region between bases -542 and -124 revealed that, in addition to the further upstream region between bases -1000 and -654, the sequences from bases -543 to -452 seemed to act as silencer regions. The oIFNtau-CAT constructs with site-specific mutagenesis revealed that multiple enhancer elements existed between bases -654 and -555 of the oIFNtau gene. On the basis of nucleotide sequence analysis, there are numerous sites between bases -654 and -555 to which potential transcriptional factors, AP-1, GATA and GATA-related proteins, could bind. Furthermore, gel mobility-shift assays revealed that AP-1 or other nuclear factors could bind to these elements. In co-transfection studies, the expression of c-Jun plus c-Fos enhanced the transactivation of oIFNtau-CAT but the expression of GATA-1, GATA-2 or GATA-3 did not. Taken together, these results suggest that the upstream region between bases -654 and -555 could be considered as the enhancer region for oIFNtau gene transactivation.

Animals↗
PubMed1999

Role of endothelin in deterioration of heart failure due to cardiomyopathy in hamsters: increase in endothelin-1 production in the heart and beneficial effect of endothelin-A receptor antagonist on survival and cardiac function.

BACKGROUND: We previously reported that chronic endothelin (ET) receptor blockade ameliorated the survival rate and cardiac hemodynamics in rats with chronic heart failure (CHF) due to myocardial infarction. However, it remains unclear whether ET-1 is involved in the pathophysiology of cardiomyopathy, which is one of the major causes of CHF. Accordingly, we investigated the production of ET-1 in the heart and the effect of chronic ETA receptor blockade on survival rate and cardiac function in the Bio 14.6 hamster, which is an idiopathic model of CHF caused by cardiomyopathy. METHODS AND RESULTS: We used 52-week-old Bio 14.6 cardiomyopathic hamsters and age-matched F1b normal hamsters. The expression of preproET-1 mRNA and the ET-1 level in the hearts were markedly higher in the cardiomyopathic hamsters than in the normal hamsters. The cardiomyopathic hamsters showed severe CHF, illustrated by lower left ventricular (LV) +dP/dt/Pmax and right ventricular (RV) +dP/dt/Pmax and by higher LV end-diastolic pressure (EDP), RVEDP, and central venous pressure compared with the normal hamsters. Long-term (9 weeks) treatment with an ETA antagonist (TA-0201, 1.3 mg. kg-1. d-1) markedly increased survival of cardiomyopathic hamsters (untreated, 16%; TA-0201-treated, 65.2%; P<0.001). After 6 weeks of treatment, LV +dP/dt/Pmax and RV +dP/dt/Pmax were significantly higher and LVEDP and RVEDP were lower in the TA-0201-treated group than in the untreated group, suggesting that chronic TA-0201 treatment effectively prevented deterioration of cardiac dysfunction. CONCLUSIONS: In the cardiomyopathic hamsters with CHF, the production of ET-1 in the heart was markedly increased, and chronic ETA receptor blockade greatly ameliorated survival and cardiac dysfunction. These results suggest that ET-1 plays an important role in the deterioration of CHF caused by cardiomyopathy, and ETA antagonists may exert therapeutic effects in CHF due to cardiomyopathy.

Animals↗
PubMed1999

Cytochrome P450 CYP1B1 determines susceptibility to 7, 12-dimethylbenz[a]anthracene-induced lymphomas.

CYP1B1-null mice, created by targeted gene disruption in embryonic stem cells, were born at the expected frequency from heterozygous matings with no observable phenotype, thus establishing that CYP1B1 is not required for mouse development. CYP1B1 was not detectable in cultured embryonic fibroblast (EF) or in different tissues, such as lung, of the CYP1B1-null mouse treated with the aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin whereas the equivalent wild-type EF cells express basal and substantial inducible CYP1B1 and lung expresses inducible CYP1B1. CYP1A1 is induced to far higher levels than CYP1B1 in liver, kidney, and lung in wild-type mice and is induced to a similar extent in CYP1B1-null mice. 7,12-dimethylbenz[a]anthracene (DMBA) was toxic in wild-type EFs that express CYP1B1 but not CYP1A1. These cells effectively metabolized DMBA, consistent with CYP1B1 involvement in producing the procarcinogenic 3,4-dihydrodiol as a major metabolite, whereas CYP1B1-null EF showed no significant metabolism and were resistant to DMBA-mediated toxicity. When wild-type mice were administered high levels of DMBA intragastrically, 70% developed highly malignant lymphomas whereas only 7.5% of CYP1B1-null mice had lymphomas. Skin hyperplasia and tumors were also more frequent in wild-type mice. These results establish that CYP1B1, located exclusively at extrahepatic sites, mediates the carcinogenicity of DMBA. Surprisingly, CYP1A1, which has a high rate of DMBA metabolism in vitro, is not sufficient for this carcinogenesis, which demonstrates the importance of extrahepatic P450s in determining susceptibility to chemical carcinogens and validates the search for associations between P450 expression and cancer risk in humans.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Regulation of flagellar bending by cAMP and Ca2+ in hamster sperm.

Hamster sperm were immotile in the medium at free Ca2+ concentrations ([Ca2+]) below 1 x 10(-4) M. The flagellum was acutely bent in the opposite direction to the curve of the hook-shaped heads. This phenomenon seemed to be caused by the decrease in the intracellular cAMP concentration, since the cAMP concentration was low at [Ca2+] below 1 x 10(-4) M and increased abruptly at 1 x 10(-3) M, at which sperm were swimming actively. In addition, sperm became motile due to treatment with 8-bromo-cAMP, a membrane permeable analogue of cAMP, in a medium without Ca2+. These results suggested that extracellular Ca2+ is involved in the regulation of flagellar movement via increasing intracellular cAMP concentration. By the treatment with W-13, a calmodulin inhibitor, sperm also became motile, although cAMP concentration remained at a low level. These results suggested that cAMP is not always required for the flagellar movement when the function of calmodulin is depressed.

Animals↗
PubMed1999

Myocardial expression of endothelin-2 is altered reciprocally to that of endothelin-1 during ischemia of cardiomyocytes in vitro and during heart failure in vivo.

We and other groups have reported that endothelin (ET)-1 expression in the heart is altered in the setting of heart diseases. We have also reported that myocardial ET-1 is involved in the progression of heart failure, and that an ET receptor antagonist improves long-term survival in heart failure (Nature 384: 353-355, 1996). However, the role of myocardial ET-2 in disease states are not known. To characterize the role of ET-2, we used a) the failing hearts of rats with heart failure caused by myocardial infarction, and b) primary cultured cardiomyocytes subjected to hypoxia. In the failing heart in vivo, ET-1 mRNA increased by 390% compared with that in the non-failing heart, while ET-2 mRNA drastically decreased by 88%. Thus, gene expression of ET-1 and ET-2 was reciprocally altered in the failing heart in vivo. In in vitro studies, reciprocal alterations in ET-1 and ET-2 gene expression were also observed in isolated primary cultured cardiomyocytes, subjected to hypoxia. Specifically, acute hypoxic stress induced a significant increase (360% of the basal level) in ET-2 mRNA expression compared with that in normoxic cells, whereas it decreased ET-1 mRNA expression by 62% in primary cultured cardiomyocytes. Although these two crucial conditions, i.e., heart failure in vivo and acute hypoxic stress in vitro, are pathophysiologically distinct from each other, reciprocal alteration of ET-1 and ET-2 gene expression was observed in both cases. To further investigate the regulatory mechanism of the altered gene expression, luciferase analysis was performed using primary cultured cardiomyocytes. ET-2 promoter, which is the 5'-flanking region of preproET-2 gene (5'ET-2), showed a marked increase in luciferase activity during acute hypoxia. In contrast, the luciferase activity of 5'ET-1 (ET-1 promoter) did not change in response to hypoxic stress. The present study suggests that there are transcriptionally distinct regulatory mechanisms for ET-1 and ET-2 expression in cardiomyocytes, and therefore this study may provide a new aspect of cardiac ET system that not only ET-1 but also ET-2 can be participated in the pathophysiological conditions.

Animals↗
PubMed1999

Analysis of hyposmolarity-induced taurine efflux pathways in the bullfrog sympathetic ganglia.

Hyposmolarity-induced taurine release was dependent on the decrease in medium osmolarity (5-50%) in the satellite glial cells of the bullfrog sympathetic ganglia. Release of GABA induced by hyposmolarity was much less than that of taurine. Omission of external Cl- replaced with gluconate totally suppressed taurine release, but only slightly suppressed GABA release. Bumetanide and furosemide, blockers of the Na+/K+/2Cl- cotransport system, inhibited taurine release by about 40%. Removal of external Na+ by replacement with choline, or omission of K+, suppressed taurine release by 40%. Antagonists of the Cl-/HCO3 exchange system, SITS, DIDS and niflumic acid, significantly reduced taurine release. The carbonic anhydrase inhibitor, acetazolamide, reduced the taurine release by 34%. Omission of external HCO3 by replacement with HEPES caused a 40% increase in the hyposmolarity-induced taurine release. Hyposmolarity-induced GABA release was not affected by bumetanide or SITS. Chloride channel blockers, 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and N-phenylanthranilic acid (DPC), practically abolished taurine release. Blockers of K+ channels, clofilium and quinidine, had no effect on the taurine release. The hyposmolarity-induced taurine release was considerably enhanced by a simultaneous increase in external K+. GABA was not mediated by the same transport pathway as that of taurine. These results indicate that Cl- channels may be responsible for the hyposmolarity-induced taurine release, and that Na+/K+/2Cl- cotransporter and Cl-/HCO3 exchanger may contribute to maintain the intracellular Cl- levels higher than those predicted for a passive thermodynamic distribution in the hyposmolarity-induced taurine release.

Animals↗
PubMed1999

Opioid receptor agonistic characteristics of mitragynine pseudoindoxyl in comparison with mitragynine derived from Thai medicinal plant Mitragyna speciosa.

We have previously elucidated the opiate-like action of mitragynine, an active principle isolated from the Thai medicinal plant Mitragyna speciosa. In the present study, effects of the related compound, mitragynine pseudoindoxyl on electrically stimulated contraction in guinea pig ileum and mouse vas deferens, and on its binding affinity in the guinea pig brain membranes were studied. Mitragynine pseudoindoxyl inhibited the electrically stimulated ileum and mouse vas deferens contractions in a concentration-dependent manner. In the ileum, the effective concentration is in an nM order, being nearly equivalent to reported concentrations of the micro-opioid receptor agonist [D-Ala2, Met-Phe4, Gly-ol5] enkephalin (DAMGO), and is 100- and 20-fold smaller than those of mitragynine and morphine, respectively. In the vas deferens, it is 35-fold smaller than that of morphine. The inhibitory action of mitragynine pseudoindoxyl in the ileum was antagonized by the non-selective opioid receptor antagonist naloxone and the micro-receptor antagonist naloxonazine. It was also antagonized by the delta-receptor antagonist naltrindole in the vas deferens. Mitragynine pseudoindoxyl showed a similar binding affinity to DAMGO and naltrindole at micro- and delta-receptors, respectively. However, the affinity at kappa-receptors was negligible. The present study demonstrates that mitragynine pseudoindoxyl, a novel alkaloid structurally different from other opioid agonists, acts on opioid receptors, leading to a potent inhibition of electrically stimulated contraction in the ileum through the micro-receptors and in mouse vas deferens through delta-receptors.

Analgesics↗