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Biomedical subjects

H Yoshida

Publications and source records attributed to H Yoshida.

At least 1,207 records · Page 67Linked to original sources
PubMed1994

dutA RNA functions as an untranslatable RNA in the development of Dictyostelium discoideum.

dutA is a gene specifically expressed during the development of Dictyostelium discoideum. Toward understanding its possible role in development, we isolated and characterized the gene and its complete cDNA. We found that dutA is encoded by the nuclear genome as a single copy gene without introns. In addition, the following unique and interesting features of dutA RNA (1322 nt) emerged: (1) it has no sustained ORFs (MAX = 126 nt) (2) it is extremely AU-rich (83%) (3) it contains peculiar sequence motifs (large palindromes, long AU-stretches and GC-clusters) (4) it is localized in the cytoplasm but completely absent from ribosomes. These features suggest that dutA RNA functions without being translated into protein. Disruption of the dutA gene did not cause phenotypic changes, suggesting that the function of dutA is redundant.

Animals↗
PubMed1994

CD3-CD8+ intestinal intraepithelial lymphocytes (IEL) and the extrathymic development of IEL.

Present evidence suggests that a majority of murine CD3+ intraepithelial intestinal lymphocytes (IEL) are extrathymically derived T cells and that these extrathymically derived IEL phenotypically express the CD8 homodimer (CD8 alpha alpha). Recently, CD3- IEL have been reported to express the recombination activating gene (RAG-1), suggesting that precursors to extrathymically derived CD3+CD8+ alpha alpha IEL exist on the intestinal epithelium. To study in detail whether these CD3-IEL can develop into CD3+CD8+ alpha alpha IEL, we analyzed the CD3-IEL subset and found that it can be separated into two subsets, namely CD3-CD8- and CD3-CD8+ IEL. We show that (1) CD3-CD8- IEL are mostly small, non-granular and phenotypically Pgp-1+ IL-2R+ B220-, while CD3-CD8+ IEL are mostly large, granular and phenotypically Pgp-1- IL-2R+ B220+, (2) CD(3-)-CD8+ IEL express the RAG-1 gene, and (3) CD3-CD8-, CD3-CD8+ and CD3+CD8+ alpha alpha IEL, respectively, appear sequentially in normal ontogeny and in bone marrow-reconstituted thymectomized radiation chimeras. In the latter, virtually all CD3+CD8+ alpha alpha IEL expressed the gamma delta T cell receptor (TCR), but not the alpha beta TCR. From this and what is presently known about T cell development, we propose that CD3-CD8+ IEL are an intermediate in extrathymic IEL development and that the development of extrathymically derived IEL occurs at the intestinal epithelium from CD3-CD8- to CD3-CD8+ to CD3+(gamma delta TCR)CD8+ alpha alpha.

Animals↗
PubMed1994

Chemometric QSAR studies of antifungal azoxy compounds.

Quantitative structure-activity relationships (QSARs) for 16 azoxy compounds with antifungal activity have been studied by the combined approach of a partial least-squares method and factorial design. The PLS model equation suggested the structural requirements of two substituents. R1 and R2, for the antifungal activity. The sterically bulky and hydrophobic R1 substituents and electron-withdrawing R2 substituents are favorable for the activity. We propose candidate compounds which are more potent than the compounds based on QSAR data. In this study, we show that the chemometric approach is a powerful tool for QSAR studies and drug design.

Antifungal Agents↗
PubMed1994

Expression of p53 protein in benign epithelial hyperplasia, atypical ductal hyperplasia, non-invasive and invasive mammary carcinoma: an immunohistochemical study.

To clarify whether p53 protein expression is involved in multistep carcinogenesis or the progression of mammary ductal carcinoma, we investigated p53 protein expression in 83 invasive ductal carcinomas (IDC), 10 IDC with a predominant intraductal component, 13 non-invasive ductal carcinoma (NIDC), 16 atypical ductal hyperplasia (ADH) and 39 benign epithelial hyperplasia (EH), using immunohistochemistry. Expression of p53 protein was detected in 24 (28.9%) cases of IDC, 5 (50%) cases of IDC with a predominant intraductal component and 1 (7.6%) case of NIDC. No expression was observed in either ADH or EH. In IDC, including cases with a predominant intraductal component, p53 protein expression was associated with a higher histological grade (P < 0.0001) or mitotic index (P < 0.0005). Although overexpression of c-erbB-2 protein has also shown a similar association with these prognostic indicators, expression of p53 protein correlated regardless of the status of c-erbB-2 overexpression. Completely coordinated expression of p53 protein was seen in both intraductal and invasive components. The intraductal component in IDC including cases with a predominant intraductal component which expresses p53 protein had significantly higher histological grade (P < 0.0005) or more comedo-subtypes (P < 0.0001). These results suggested that p53 protein expression occurs at a stage of NIDC with high histological grade or in comedo-subtypes. Its expression is maintained throughout invasion.

Breast↗
PubMed1994

Prevalence of Raynaud's phenomenon in different groups of workers operating hand-held vibrating tools.

In eight groups of subjects operating various hand-held vibrating tools and aged from 30 to 59 years, the prevalence rates of vibration-induced white finger (VWF) and numbness, pain, or stiffness in the upper and lower extremities were investigated. Hand-transmitted vibration levels (HTVLs) were measured on the back of the hand, by means of unidirectional (x-axis) vibration dosimeters, and the frequency-weighted acceleration levels [(Lh,w)eq,t] were determined as the vibration levels. The prevalence rates of VWF and numbness of the hands in these subjects were compared to the prevalence rates of Raynaud's phenomenon (RP) and numbness of the hands in 1027 males and 1301 females not occupationally exposed to vibration (age range: 30-59 years). It was observed that in subjects exposed to HTVLs of between 1.1 and 2.5 m/s2, the prevalence of VWF was between 0.0% and 4.8%. The prevalence of VWF reached 9.6% in a group of workers exposed to HTVLs of 2.7-5.1 m/s2. The latter group showed a significant difference (P < 0.05) in the prevalence of VWF compared to the 2.7% prevalence of RP in male subjects of the general population. The prevalence of VWF in female subjects exposed to vibration (4.3%) was not significantly different from the prevalence of RP in females of the general population (3.4%). The prevalence rates of numbness of the hands were in the range of 6.5%-30.4% in the exposed groups and in the range of 13.4%-29.5% in the general population. Among the subjective symptoms, only VWF showed a significant positive correlation with HTVLs (R2 = 0.5, P < 0.05). It was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be employed. With a view to decreasing the risk of developing VWF, estimated vibration safety values for 4 h and 2 h daily exposures are discussed.

Adult↗
PubMed1994

Pharmacokinetics of doxorubicin and its active metabolite in patients with normal renal function and in patients on hemodialysis.

The comparative pharmacokinetics of doxorubicin (DOX) were investigated in five hemodialysis (HD) and eight non-hemodialysis (non-HD) patients who were infused with a 40- to 60-mg dose of DOX at a constant rate over 30 min. A significant difference was observed in the total body clearance (Cl tot) of DOX between HD and non-HD patients. The area under the curve (AUC) for both DOX and doxorubicinol (DOXol), an active metabolite, showed increases of approximately 1.5 and 3 times in HD patients as compared with non-HD patients. Although these differences were not statistically significant (P < 0.1), the mean residence time (MRT) of DOX and DOXol in HD patients showed a 2-fold increase in comparison with those in non-HD patients. Compartmental analysis indicated that the greater AUC values and longer MRT of DOX and DOXol in HD patients resulted from the lesser DOXol formation and disappearance of rate constants. As a consequence of the decrease in Cl tot for DOX and the marginal hemodialysis clearance of both DOX and DOXol, the present study suggests that the exposure to DOX and DOXol obtained in HD patients greater than achieved in non-HD patients. Careful attention should therefore be paid to HD patients receiving DOX.

Aged↗
PubMed1994

Re-evaluation of classic senile plaques by three-dimensional analysis.

We evaluated the proportion of classic plaques among all of the senile plaques in four Alzheimer brains (frontal, temporal, occipital and hippocampal areas) by the usual method of two-dimensional analysis using a single methenamine silver-stained section and three-dimensional analysis using a set of serial sections. Three-dimensional analysis showed the number and percentage of classic plaques to be 2-5 times greater than those revealed by two-dimensional analysis. In the hippocampal area of one case, no classic plaques were found by two-dimensional analysis but three-dimensional analysis showed that some classic plaques were present. From these findings, it is suggested that three-dimensional analysis using serial sections is indispensable for subclassifying senile plaques.

Aged↗
PubMed1994

Density-associated changes in platelet-activating factor acetylhydrolase activity and membrane fluidity of human erythrocytes.

Platelet-activating factor acetylhydrolase is known to degrade oxidatively fragmented phospholipids which are similar in structure to platelet-activating factor. We examined changes of acetylhydrolase activity during in vivo aging of human erythrocytes and tried to assess its role in maintaining the membrane properties of erythrocytes. Higher-density erythrocytes are enriched with older cells. Erythrocytes obtained from seven healthy colleagues were separated into four density fractions by centrifugation in discontinuous Percoll density gradients. Both membrane and cytosolic acetylhydrolase decreased with increasing erythrocyte density. Membrane and cytosolic acetylhydrolase activities in the lightest fraction were 2.0 +/- 1.0 (SD) nkat/g protein and 362 +/- 58 pkat/g protein, respectively, and these values were significantly higher than those in the densest fraction: 1.3 +/- 0.7 nkat/g protein and 286 +/- 70 pkat/g protein, respectively. Membrane acyltransferase activity also decreased with red cell density and the average values in the lightest and densest fractions were 51.2 +/- 23.6 and 27.0 +/- 20.2 mukat/g protein, respectively. Generation of thiobarbituric acid-reactive substances induced by t-butyl hydroperoxide treatment decreased with increasing cell density, and the inhibition of acetylhydrolase with diisopropylfluorophosphate resulted in enhanced peroxide-induced lipid oxidation, particularly in lower-density fractions. There was no significant change in basal levels of thiobarbituric acid-reactive substances in red cell membrane. Membrane fluidity was evaluated by fluorescence recovery after photo-bleaching and it decreased as erythrocyte density increased. We conclude that the activity of the deacylation/reacylation cycle maintained by acetylhydrolase and acyltransferase is gradually reduced during in vivo aging of erythrocytes. This may be connected with decreases of polyunsaturated fatty acids and membrane fluidity in old erythrocytes.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1994

Bile flow in a mutant Sprague-Dawley rat with defective biliary excretion of glutathione.

The Eisai hyperbilirubinemic rat is a mutant strain of Sprague-Dawley origin with hereditary defects in the biliary excretion of bilirubin glucuronide, glutathione, and several other organic anions. The correlation between bile flow and bile acid excretion rates during taurocholate infusion revealed that bile acid-independent flow was smaller in the mutant than in intact Sprague-Dawley rats (19.3 vs 56.0 microliters/kg per min), while bile acid-dependent flow was similar. The correlation between bile flow and glutathione excretion rates in Sprague-Dawley rats with modified hepatic glutathione levels revealed that a certain portion of bile flow was proportional to the biliary excretion of glutathione, with a coefficient of 551 bile per 1 mol glutathione. One-third of bile acid-independent bile flow in intact Sprague-Dawley rats was accounted for by glutathione osmosis, which feature was absent in the mutant rats.

Animals↗
PubMed1994

Value of thallium-201 early reinjection for assessment of myocardial viability.

To assess the efficacy of early reinjection for predicting post intervention improvement in thallium-201 (T1) uptake and regional wall motion, we reinjected a small dose of T1 following post-stress imaging and obtained reinjection early images (10 min after early reinjection) and reinjection delayed images (3 hr afterwards) in 40 patients who were referred to us for revascularization (group I). Twenty-nine patients in group I also underwent conventional stress-redistribution T1 scintigraphy (group II). Conventional stress-redistribution T1 scintigraphy was repeated after intervention. Contrast left ventriculography was performed before and after intervention and changes in regional wall motion were assessed in 22 of 40 patients. In group I, the predictive value for improvement and no improvement (the accuracy) of reinjection early images in perfusion was 83%, while that of reinjection delayed images was 91%. Furthermore, the accuracy of reinjection early images in regional wall motion was 80%, while it was 91% for reinjection delayed images. In group II, the accuracy in perfusion was 78% and the value in regional wall motion was 70%. Both accuracy in perfusion and in regional wall motion obtained from reinjection delayed images were significantly higher than the values in group II (p < 0.05). These data suggest that early reinjection is useful for predicting postintervention thallium uptake and regional wall motion.

Aged↗
PubMed1994

A clinical feature of myocardial stunning associated with acute myocardial infarction.

We report a case of myocardial stunning after acute myocardial infarction. In the hyperacute phase of myocardial infarction, the patient's coronary arteries showed normal features on coronary angiography during extensive ST-segment elevation observed on a standard 12-lead electrocardiogram and extensive akinesis observed on a left ventriculogram. Thallium-201 emission computed tomography revealed extensive perfusion abnormality. In the chronic phase, the perfusion abnormality was markedly improved. However, the electrocardiogram demonstrated poor R wave progression, and the left ventriculography revealed slight hypokinesis in the anterolateral wall. The acetylcholine provocation test disclosed coronary vasospasm of the left anterior descending coronary artery. About six months thereafter, left ventricular wall motion became completely normal and no poor R wave progression was observed on the electrocardiogram. The findings in this case indicate that myocardial stunning resulted from brief but sever ischemia due to vasospasm which led to cardiogenic shock, and that the recovery of findings for thallium-201 perfusion might be followed by those of electrocardiography and left ventriculography in the stunned myocardium.

Acetylcholine↗
PubMed1994

New approach to aortic dissection: development of an insertable aortic prosthesis.

We have developed a new aortic prosthesis with which we can replace or reinforce the aorta using a simple percutaneous technique. We have named the new prosthesis the shape-memory aortic prosthesis (SAP); it consists of a spiral-shaped nitinol stent and polyurethane tube. It can be compressed inside a 14F catheter at a low temperature and regain its original shape at above 30 degrees C. As a preliminary study, SAP sutureless grafting into the descending aorta was performed on 10 mongrel dogs. We found that when the proper diameter of SAP was applied, it functioned satisfactorily for 3 months or more. A percutaneous placement technique pertinent to the SAP also was developed and tried on 4 animals. Our procedure was applied to Stanford type B dissection models to close the entry point successfully. This newly developed SAP has potential to be applied to emergency cases of human aortic dissections.

Aortic Dissection↗
PubMed1994

Immunoreactive endothelin-1 concentrations in follicular fluid of women with and without endometriosis undergoing in vitro fertilization-embryo transfer.

OBJECTIVE: To determine the concentrations of immunoreactive (IR) endothelin-1 in human follicular fluid (FF) and whether IR-endothelin-1 levels are different in women with endometriosis-associated infertility. DESIGN: Follicular fluid and plasma samples, obtained from women with and without endometriosis undergoing IVF-ET, were collected at the time of oocyte aspiration and analyzed for IR-endothelin-1 levels. SETTING: Infertility clinic in an academic research environment. RESULTS: Overall, 90% of FF samples and 60% of plasma samples contained IR-endothelin-1 detectable above the threshold of assay sensitivity. Immunoreactive endothelin-1 levels (mean +/- SEM) in FF samples from women with and without endometriosis-associated infertility were 74 +/- 12 and 37 +/- 6 pg/mL, respectively. There was no difference in IR-endothelin-1 levels in FF samples between controlled ovarian hyperstimulation cycles with or without leuprolide acetate. No significant differences were detected in plasma IR-endothelin-1 levels in women with endometriosis-associated infertility when compared with those without. CONCLUSIONS: These results demonstrate the presence of IR-endothelin-1 in human FF obtained at the time of oocyte aspiration for IVF-ET and higher levels of IR-endothelin-1 in FF of women with endometriosis-associated infertility.

Adult↗
PubMed1994

Ultrastructure of the intracellular membranous system of rat hepatocytes in intrahepatic cholestasis induced by phalloidin.

To investigate the effect of a thickened pericanalicular ectoplasm in tubulovesicular transport and biliary excretion, we examined the ultrastructure of the intracellular membranous system in rat hepatocytes with and without phalloidin treatment, by transmission electron microscopy and scanning electron microscopy combined with the Aldehyde prefix Osmium-Dimethyl Sulfoxide-Osmium method. Hepatocytes possessed elaborate networks of tubules around bile canaliculi, and some of them extended to the bile canaliculi in control rats. Vesicles were also present around the bile canaliculus. Treatment of rats with phalloidin produced a thick pericanalicular ectoplasm around the bile canaliculus visualized by transmission electron microscopy, and the density of vesicles (p < 0.001) and tubules (p < 0.001) within 0.5 microns around the bile canaliculus significantly decreased in phalloidin-treated rats. The number of lysosomes in hepatocytes apparently increased in phalloidin-treated rats; however, they were rarely observed around the bile canaliculus. The Aldehyde prefix Osmium-Dimethyl Sulfoxide-Osmium method produced an organelle-free space around the bile canaliculus by removing the thick pericanalicular ectoplasm in scanning electron microscopic examination, and the thickened pericanalicular ectoplasm inhibited the approach of intracellular membranes to the canalicular membrane in the transmission electron microscopic examination. In some pathological cholestatic conditions, the thickened pericanalicular ectoplasm may inhibit not only bile canalicular contraction but also biliary excretion of substances, which is mediated by the tubulovesicular transport system.

Animals↗
PubMed1994

The effect of selective growth hormone defect in the progression of glomerulosclerosis.

The role of endogenous growth hormone (GH) in the progression of glomerulosclerosis was examined in a new mutant strain of Sprague-Dawley (SD) rats with a selective GH gene defect. Fifteen spontaneous dwarf [GH(-)] rats and 10 SD rats underwent subtotal nephrectomy (Nx) or sham operation. Twelve weeks after Nx, the mean arterial pressure, glomerular filtration rate, urinary protein excretion rate, glomerular size, and frequency of glomerulosclerosis were examined. Marked elevation in mean arterial pressure was seen in both SD/Nx and GH(-)/Nx rats. In both strains, the glomerular filtration rate at 12 weeks after Nx was approximately 50% to 60% of that seen in the respective Sham-operated rat groups. The urinary protein excretion rate increased significantly only in the SD/Nx rats. The glomerular size, expressed as the ratio of glomerular volume to body weight, increased by 200% in the SD/Nx rats compared with the SD/Sham rats, in marked contrast to the 70% increase in the GH(-)/Nx rats compared with the GH(-) rats. The frequency of glomerulosclerosis in the GH(-)/Nx rats (1.0 +/- 0.5%) was significantly lower than that in the SD/Nx rats (16.7 +/- 2.8%). The frequency of glomerulosclerosis correlated with glomerular hypertrophy in both the SD and GH(-) rats (r = 0.88 and 0.67, respectively). These results show that the progression of glomerular sclerosis was markedly attenuated in the GH-defective rats. This attenuation of structural injury was correlated with a marked decrease in glomerular hypertrophy. These studies indicate that this specific growth regulatory peptide of endogenous origin plays an important determining role in the progression of glomerulosclerosis.

Analysis of Variance↗