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Biomedical subjects

Y H Hu

Publications and source records attributed to Y H Hu.

At least 37 records · Page 2Linked to original sources
PubMed1996

Galpha12 and galpha13 are phosphorylated during platelet activation.

The ubiquitously expressed G-proteins G12 and G13 whose function is currently not clear have been shown to be activated in platelet membranes through receptors that stimulate platelet aggregation. We used intact human platelets to determine whether alpha subunits of both G-proteins can be phosphorylated under physiological conditions. Activation of human platelets by thrombin and the thromboxane A2 receptor agonist U46619 lead to phosphorylation of Galpha12 and Galpha13. Phosphorylation occurred rapidly after addition of thrombin and was not mediated by glycoprotein IIb/IIIa (integrin alphaIIbbeta3) activation. Phosphorylation of Galpha12 and Galpha13 could be mimicked by phorbol 12-myristate 13-acetate, and thrombin-induced phosphorylation was inhibited by the protein kinase C inhibitor calphostin C indicating an involvement of protein kinase C in Galpha12/13 phosphorylation induced by thrombin in human platelets. The phosphorylation of both G protein alpha subunits was reconstituted in COS-7 cells cotransfected with Galpha12 or Galpha13 and different protein kinase C isoforms. Among the protein knase C isoforms tested, protein kinase C beta, delta, and epsilon were most effective in promoting phosphorylation of Galpha12 and Galpha13 in a phorbol 12-myristate 13-acetate-dependent manner. These data demonstrate that Galpha12 and Galpha13 are phosphorylated under in vivo conditions and that this phosphorylation involves protein kinase C.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Birth season and breast cancer risk in Japan.

Recent studies suggest that prenatal or early post-natal factors may influence future breast cancer risk. To investigate whether month of birth is a risk factor for breast cancer, we analyzed the distribution of month of birth for 81,162 women died of breast cancer and 1,334,650 women died of cancers at all sites, who were reported to the Ministry of Health and Welfare from 1972-90 in Japan. After considering each birth year seasonal variations in month of birth were not shown statistically significant in any age-group through using chi 2 test (df = 11). The negative results were also confirmed in residential area and period category.

Breast Neoplasms↗
PubMed1996

Sequences and comparisons of duck mitochondrial DNA control regions.

In this study, the nucleotide sequences of the displacement loop (D-loop) and the ribosomal RNA genes of mitochondrial DNA (mtDNA) were determined from a representative each of two genera of ducks, Cainina muschata and Anas platyrhynchos. The duck mtDNA shows a specific gene order at 5' upstream of D-loop (5'ND6-tRNA(Glu)-D-loop3') that is identical to chick mtDNA but is different from that of mammalian or amphibian (5' cytochrome b-tRNA(Thr)-tRNA(Pro)-D-loop3'). Nucleotide diversity is greatest in the D-loop while being most conserved in the 12S rRNA gene, as indicated from a sequence comparison between duck and chick mtDNA. A consensus sequence in the D-loop region, which may play influential roles in the regulation of transcription and replication of mtDNA, was found in both CSB-1 and repeated sequences of birds. Sequences of four tRNA genes in this region are also reported. Among them, tRNA(Glu) shows the greatest sequence divergence when different order of birds are compared.

Animals↗
PubMed1996

A DEAD-box-family protein is required for nucleocytoplasmic transport of yeast mRNA.

An enormous variety of primary and secondary mRNA structures are compatible with export from the nucleus to the cytoplasm. Therefore, there seems to be a mechanism for RNA export which is independent of sequence recognition. There nevertheless is likely to be some relatively uniform mechanism which allows transcripts to be packaged as ribonucleoprotein particles, to gain access to the periphery of the nucleus and ultimately to translocate across nuclear pores. To study these events, we and others have generated temperature-sensitive recessive mRNA transport (mtr) mutants of Saccharomyces cerevisiae which accumulate poly(A)+ RNA in the nucleus at 37 degrees C. Several of the corresponding genes have been cloned. Upon depletion of one of these proteins, Mtr4p, conspicuous amounts of nuclear poly(A)+ RNA accumulate in association with the nucleolus. Corresponding dense material is also seen by electron microscopy. MTR4 is essential for growth and encodes a novel nuclear protein with a size of approximately 120 kDa. Mtr4p shares characteristic motifs with DEAD-box RNA helicases and associates with RNA. It therefore may well affect RNA conformation. It shows extensive homology to a human predicted gene product and the yeast antiviral protein Ski2p. Critical residues of Mtr4p, including the mtr4-1 point mutation, have been identified. Mtr4p may serve as a chaperone which translocates or normalizes the structure of mRNAs in preparation for export.

Amino Acid Sequence↗
PubMed1996

[A five years surveillance on neural system birth defects in rural areas of China].

A total number of 167,274 births were observed on birth defects in rural areas 1968-1990 in China. The results showed that there were 361 cases of neural system defects, accounting for 31.45% in all birth defects. The incidence of neural system defects was 2.19% with hydrocephalus, anencephalus and spinal bifida 0.89%, 0.87%, 0.36% respectively. The distribution of neural system birth defects showed that incidence in northern part of the country was higher than that of in the south while in winter--spring was higher than in summer--autumn. Results of unconditional logistic regression analysis demonstrated that risk factors were related to neural system defects as maternal education level, parity, delivery mode and lower birth weight.

Anencephaly↗
PubMed1996

[Clinical and experimental study on effect of ganyan IV in treatment of chronic active hepatitis complicated with hyperbilirubinemia].

Sixty chronic active hepatitis patients complicated with hyperbilirubinemia (total bilirubin > 171 mumol/L) were treated with combined treatment of Ganyan IV and Western medicine. The curative effect was compared with that treated with Western medicine alone as control (56 cases). Result showed that the effect of combined therapy group was much better than that of the control in eliminating the jaundice, descending the alanine transaminase (ALT) and improving the reversed A/G ratio (P < 0.05-0.001). In experimental studies, Ganyan IV was applied to the mice with acute liver damage formed by CCl4. It also showed significant effect on reducing total bilirubin and elevating the serum albumin statistically as compared with control (P < 0.05 = 0.01). In addition Ganyan IV could accellerating the bile excretion of normal as well as of liver damaged rats significantly. It was concluded that the Ganyan IV has the effects of treating jaundice, descending transaminase, elevating serum albumin and improving A/G ratio.

Adolescent↗
PubMed1995

Experimental study of corneal innervation in diabetic mellitus.

The morphology of corneal innervation was studied in rabbits with alloxan-induced diabetes. The experimental rabbits were killed after 6, 8, 10, 12 weeks. Corneal innervation was studied by histochemical techniques and transmission electron microscopy. The results revealed that in diabetic rabbits, from 6 weeks, the density of nerve-nets was markedly sparser, the fibers were thinner and the activity of nerves was lower than those of the control group. Ultrastructural changes showed swelling of axons, irregular distribution of fibril and degeneration of mitochondria of varying degree. With the progress of disease the above changes were becoming more marked gradually. It may be assumed that these changes are related to hyperglycemia.

Animals↗
PubMed1995

Effects of menstrual and reproductive factors on the risk of breast cancer: meta-analysis of the case-control studies in Japan.

To elucidate the magnitude of the effect of menstrual and reproductive factors on breast cancer occurrence among Japanese women, we reviewed eight case-control studies previously conducted in Japan and used a quantitative method (meta-analysis) to summarize the data. While individual studies have different methods and populations, the estimated odds ratios (ORs) in the studies were statistically homogeneous for all study variables. It was confirmed that early age at menarche, late age at first birth, and premenopausal status are significantly associated with risk of breast cancer; an estimated combined OR of 0.68 (95% confidence interval (CI): 0.59-0.77) was obtained for women with onset of menstruation after age 16 compared to those before age 14. Nulliparous women had higher risk than women with first birth before age 25 (OR = 1.56 95%, CI: 1.27-1.91). The OR for women with first birth after age 35 was 2.26 (95% CI: 1.85-2.77) compared to women at first birth before age 25. Premenopausal women had a higher risk than women with menopause before age 50 (OR = 2.21, 95% CI: 1.53-3.20). We also found a significant protective effect of high parity after controlling for age at first birth and the other menstrual factors. The OR estimate for 3 or more births compared to nulliparity was 0.68 (95% CI: 0.54-0.86). The meta-analysis provided quantitative estimates of breast cancer risk among Japanese women with improved precision.

Age Factors↗
PubMed1995

[Experimental study on cell cycle in rabbits' aortic smooth muscle cell culture in vitro with tongmai jiangzhi liquor].

The effects of Tongmai Jiangzhi Liquor (TMJZL) on the cell cycle kinetics in smooth muscle cell (SMCO of rabbits' midlayer of aortic wall was observed. It was showed that TMJZL could extend the time of cell culture, lower the percentage of SMC in G0/G1 phase and elevate the percentage of SMC in S phase gradually. The higher the concentration, the stronger the effect. The experiment showed that TMJZL had a marked inhibition of SMC of rabbits' midlayer of aortic wall cultured in vitro.

Animals↗
PubMed1994

Thymocyte apoptosis induced by elevated endogenous corticosterone levels.

A well-known model of apoptosis is induction in thymocytes by injection of pharmacological doses of exogenous steroids. The aim of this study was to investigate whether this process also occurs under physiological conditions, i.e. by stimulation of endogenous glucocorticoid release, using the chicken as an experimental model. Endogenous glucocorticoid levels can be elevated by immunization with exogenous antigens or by injection of conditioned medium, e.g. supernatant of mitogen-stimulated spleen cells. This effect is mediated by so-called glucocorticoid-increasing factors, and is considered to act as an immunoregulatory principle. Thymocyte DNA of so treated birds showed a typical "ladder" pattern after electrophoresis in a 1.8% agarose gel, and degradation could be prevented by RU 38,486. This provides evidence that apoptosis can be induced by elevating endogenous corticosterone levels in vivo. By means of in situ nick translation (ISNT) and simultaneous immunofluorescence tests, it was possible to analyze various thymic subpopulations during apoptosis after treatment with exogenous glucocorticoids. Additionally, using confocal microscopical techniques, apoptosis of the same cells as analyzed by ISNT is shown. The possible role of elevated concentrations of endogenous glucocorticoids in regulating thymocyte cell death and autoimmune diseases is discussed.

Animals↗
PubMed1994

Changes in cardiovascular activity during an increase in biliary tract pressure in rabbits.

In order to study the mechanism of decreased blood pressure caused by an acute increase in biliary tract pressure, we observed house rabbit model of self-made caecus for changes in cardiovascular function when biliary tract pressure was increased. It was found that both the blood pressure and cardiac output evidently decreased (P < 0.05) parallelly, and the systolic pressure decreased more markedly than diastolic pressure. At the same time there was fluctuation in heart rate and in central venous pressure; but there was no significant difference between them (P > 0.05), suggesting that in the absence of infective agents, the increased biliary tract pressure can bring about a decrease in cardiac output, which is an important factor contributing to an early blood pressure decrease in acute cholangitis of severe type (ACST).

Animals↗
PubMed1994

Effect of increasing biliary tract pressure on house rabbit blood dynamics in acute cholangitis of severe type.

In this study 12 Japanese long ear rabbits were used as models of acute cholangitis of severe type (ACST), and also an increasing pressure apparatus of self-made caecus to form high pressure of the biliary tract. The animals were observed for changes in blood dynamics in an attempt to explore the effect and relation of high pressure of biliary tract and infective element in pathogenesis of ACST. It was found that when the biliary pressure was increased within 120 min in the 20 kPa group, the blood endotoxin level showed no obvious increment (P > 0.05), but the decreased range of average MAP (mean artery pressure) was over 4 kPa, and the cardiac output also decreased evidently (P < 0.05), and that when the biliary pressure was decreased, MAP and cardiac output were restored to normal gradually. Of these animals 3 didn't restore their normal condition when the blood pressure decreased to zero and died finally. Meanwhile the electric discharge frequency of the right greater splanchnic nerves increased (P < 0.05), but when pressure was reduced, the frequency slowed down. From the above findings, the authors came to the conclusion that the rapid increase of the biliary tract pressure is the important factor leading to a decrease in blood pressure of ACST, and even bringing about irreversible shock, which is involved in the activity of splanchnic nerves.

Acute Disease↗
PubMed1994

[Essential hypertension: a predictor of the 6 year-incidence of NIDDM in 465 non-diabetics].

The effect of essential hypertension at baseline on the development of NIDDM within 6 years was investigated in 465 Chinese nondiabetics with or without hypertension. The age, sex adjusted 6 year incidence of NIDDM in hypertensive group (BP > 18.7 +/- 12. okPa (140/90 mmHg) or treated with antihypertensives) at baseline was significantly higher than that in normotensive group (44.6%, n = 325, P < 0.05) at baseline. Multivariate regression analysis showed the hypertensive group had higher risk of worsening to diabetes compared with normotensives (OR: 1.82, 95% Ci: 1.03-3.21, P < 0.05) after the adjustment for two other important risk factors for NIDDM, the fasting plasma glucose and BMI. Further more the increasement of SBP by 20 mmHg at baseline significantly increase the risk for NIDDM in the followup period in the blood-lowering-drug-free group (OR: 1.54, 95% Ci: 1.05-2.24, P < 0.05). Thus it confirmed that hypertension at baseline was an independent predictor for NIDDM. In addition, our observation showed that some antihypertensive drugs appears also to play an unfavorable role in the occurrence of NIDDM.

Adult↗
PubMed1993

Increasing trends in mortality rate of aortic aneurysms in Japan, 1955-90.

To know the characteristics of mortality from aortic aneurysms in Japan, the age-adjusted and age-specific mortality rates of the diseases were calculated based on the Vital Statistics of Japan published from the Statistics and Information Department, Minister's Secretariat, Ministry of Health and Welfare. The overall age-adjusted mortality rate increased 24.8-fold from 0.43 to 10.98 per 100,000 for males, and 18.6-fold from 0.23 to 4.54 per 100,000 for females from 1955-90. The most common type was abdominal aortic aneurysms followed by dissecting and thoracic aortic aneurysms. The mortality rates of dissecting and thoracic aortic aneurysms increased greater than that of abdominal aortic aneurysms. The mortality rate of dissecting aneurysms was higher than that of abdominal and thoracic aortic aneurysms in age groups of 64 years or under. The mortality rate of abdominal aortic aneurysms was the most common in age groups of 65 years or over.

Adult↗
PubMed1993

Impaired glucose tolerance and its relationship to ECG-indicated coronary heart disease and risk factors among Chinese. Da Qing IGT and diabetes study.

OBJECTIVE: To determine the prevalence of IGT and diabetes and identify the occurrence of CVD and its risk factors. RESEARCH DESIGN AND METHODS: This study was a population-based, cross-sectional study of 110,660 residents, 25-74 yr of age of DaQing, Hei Long Jiang Province, China. RESULTS: Using 1985 WHO criteria, 577 (5.5/1000) subjects with IGT and 630 (6.0/1000) with newly diagnosed diabetes were identified. In addition, 190 (1.7/1000) with previously known diabetes were identified. Hypertension, obesity, and abnormal albumin excretion were twice as frequent in those with IGT as in 279 men and 240 women of similar age and sex distribution who had normal OGTTs. Plasma cholesterol and TGs were higher, and HDL cholesterol was lower in subjects with IGT than in nondiabetic subjects. Those with IGT had a prevalence of electrocardiographically recognized CHD 9.5-fold greater than the normoglycemic subjects. Subjects with IGT had higher plasma insulin concentrations, but the 1-h insulin-glucose ratio after the 75-g glucose load was lower. In a forward stepwise multiple logistic regression analysis, IGT itself remained an independent factor associated with CHD after adjustment for age, sex, cigarette smoking, plasma cholesterol, BP, and obesity. CONCLUSIONS: Therefore, in China, IGT may occur with almost as high a frequency as diabetes and is accompanied by an increased frequency of CVD and its risk factors. Estimates from this study indicate that > 12.0% of all ECG-indicated CHD in the Da Qing population occurs in individuals with IGT and NIDDM. The IGT subjects identified in this survey form the cohort for a long-term follow-up and intervention study.

Adult↗
PubMed1993

Applications of artificial neural networks for ECG signal detection and classification.

The authors have investigated potential applications of artificial neural networks for electrocardiographic QRS detection and beat classification. For the task of QRS detection, the authors used an adaptive multilayer perceptron structure to model the nonlinear background noise so as to enhance the QRS complex. This provided more reliable detection of QRS complexes even in a noisy environment. For electrocardiographic QRS complex pattern classification, an artificial neural network adaptive multilayer perceptron was used as a pattern classifier to distinguish between normal and abnormal beat patterns, as well as to classify 12 different abnormal beat morphologies. Preliminary results using the MIT/BIH (Massachusetts Institute of Technology/Beth Israel Hospital, Cambridge, MA) arrhythmia database are encouraging.

Arrhythmias, Cardiac↗