Search PubMed⌕ Search

Biomedical subjects

Y Hu

Publications and source records attributed to Y Hu.

At least 595 records · Page 33Linked to original sources
PubMed1994

Restrictive fragment length polymorphisms of markers 3'HVR and 24-1 and their applications in gene diagnosis of adult polycystic disease in Chinese.

Adult polycystic kidney disease was diagnosed with pedigree analysis using polymorphic DNA markers linked to the disease gene in 5 families. The markers were thoroughly characterized in the population. We noted two important markers, 3'HVR and 24-1, which flank the disease gene PKD1 in normal Chinese. Southern hybridization was used, and numerous 3'HVR/PvuII polymorphic allelic bands varied from 1.4 kb to 8.0 kb with a positive skew distribution. They were divided into 11 groups with an interval of 0.6 kb and a heterozygosity rate of 0.86. Allele frequencies were observed. When the probe 24-1 was hybridized with genomic DNA digested by TaqI, two alleles, B1 and B2, were detected with frequencies of 0.76 and 0.24, respectively. B1 was 3.8 kb in size and B2 was composed of 2 bands, 1.5 kb and 1.3 kb. The polymorphism information content was found to be 0.297. Using these two markers for linkage analyses of 5 affected families, we confirmed the linkage between 3'HVR and the disease gene PKD1 and made presymptomatic diagnosis of the members at risk.

Alleles↗
PubMed1994

[Epidemiologic features and the stepwise regression analysis of fatal motor vehicle accidents in Guangzhou].

This paper describes the epidemiologic features of 1,532 fatal motor vehicle crashes, and analyses of some crash-related factors by means of stepwise regression analysis as well. The crashes between motor vehicle and bicycle accounted for 39.49 percent. The 36.84 percent of drivers responsible for accidents were at the age of 20-24. The analysis of accident victim characteristics indicated that all age groups were at risk. Most victims were the people younger than 25 years old as well as aged 50 and over. About one-third of the victims were peasants. The analysis of stepwise regression suggested that the crashes were positively related to the quantity of automobile and the ratio between male and female.

Accidents, Traffic↗
PubMed1994

[Experimental study on the role of oxygen-free radicals in ischemic reperfusion tissue injury is island skin flaps].

In this study the role of oxygen-free radicals and the effect of treatment with superoxide dismutase (SOD) had been investigated in a 3 x 6 cm2 abdominal area island skin flaps of rat model which were subjected to 8 hours of total venous occlusion. In experiment 1, 56 rats were divided into seven test groups. Tissue assay for Malonydialdehyde (MDA) were obtained. Flaps with ischemia had higher MDA at 8.12 hours and all reperfusion groups had higher MDA as compared to the control groups (P < 0.01). In reperfusion groups, the MDA had increased at 4.8 hours compared to ischemia group at the same time. In experimental 2, 28 rats were used. Treatment with superoxide dismutase injected into the artery following the onset of reperfusion significantly enhanced island flap survival from 28.6% (4/14) to 78.6% (11/14) (P < 0.01).

Animals↗
PubMed1994

Chlormethiazole as an efficient inhibitor of cytochrome P450 2E1 expression in rat liver.

Ethanol-inducible cytochrome P450 (CYP) 2E1 (CYP2E1) is responsible for the metabolism of many xenobiotics which exert toxic effects in humans. Specific inhibitors might constitute valuable tools in the elucidation of the pharmacological and toxicological roles of this isozyme in vivo. In the present investigation we have evaluated the effects of a drug used for treatment of ethanol withdrawal states, chloromethiazole (CMZ), on CYP2E1 expression in rat liver. A 4-fold induction of CYP2E1 was observed after 3 days of starvation, accompanied by a similar increase in the level of the corresponding mRNA. CMZ specifically inhibited the elevation of CYP2E1 mRNA and protein, but did not prevent CYP2B1 and CYP3A1 or CYP1A1 induction caused by treatment with phenobarbital or beta-naphthoflavone, respectively. From nuclear run-off experiments it was apparent that the rate of the CYP2E1 gene transcription was inhibited greatly by CMZ treatment. Rats treated with ethanol in a total enteral nutrition model had higher CYP2E1-dependent hepatic microsomal activities of p-nitrophenol hydroxylase and carbon tetrachloride-induced lipid peroxidation than controls, and simultaneous CMZ treatment abolished the ethanol-dependent induction. In vitro experiments with rat liver microsomes showed that CMZ did not act as an inhibitor of CYP2E1-dependent catalytic activities or as an inhibitor of microsomal NADPH and CYP2E1-dependent lipid peroxidation. In conclusion, we suggest that CMZ might constitute an efficient and specific inhibitor of CYP2E1 expression suitable for in vivo experiments.

Animals↗
PubMed1994

[Recurrent astrocytoma versus primary astrocytoma: a comparative study of morphological changes of 32 cases].

The pathologic morphological changes of 32 cases of recurrent astrocytoma (RA) and primary astrocytoma were reported. During recurrence, 20 cases (62.5%) of astrocytomas transformed into cases at higher grades. Twelve cases remained at the same grades as primary tumors. Among 21 cases of RA at grades III and IV, 15 cases (71.4%) came from primary astrocytomas, grades I and II. The change from astrocytoma grade I to grade III or IV took time longer than that from grade II to grade III or IV. The recurrent time of astrocytomas with different grades showed no statistical differences. Postoperative radiotherapy/chemotherapy did not play a major role in grading changes and recurrent time.

Adult↗
PubMed1994

[The effects of hypertonic and balanced saline solutions on burn shock resuscitation in burned rats].

Hypertonic saline solution (HS) has been used effectively to treat different kinds of shock. In this experiment, all rats are inflicted with a full-thickness burn of 20% BSA, and they are divided into three groups. Group I, control; group II, resuscitated with balanced saline solution; group III, with HS. All animals are sacrificed at 24 hours postburn to determine blood viscosity (BV) and tissue water content (TWC), as well as to observe the microcirculation in kidney with electronmicroscopy. We find that the TWC increased significantly in group II (P < 0.05), while BV decreased, especially in group III (P < 0.01). The electronmicroscopic observation indicates that: In group I, there are capillary dilatation, red cell aggregation, endothelium edema, and appearance of many gaps between endothelium. In group II, the blood flows easily and smoothly. In group III, the improvement of microcirculation is not significant and the blood vessel is filled with microthromboli. The results show that HS can improve systemic circulation, but not microcirculation.

Animals↗
PubMed1993

Isolation and characterization of the murine homeobox gene Cdx-1. Regulation of expression in intestinal epithelial cells.

The murine homeobox gene Cdx-1 is postulated to play an important role in the process of cellular commitment in the intestinal epithelium based upon its graded, tissue-specific expression pattern in the adult animal. We have isolated and sequenced both cDNA and genomic clones in order to understand how this expression pattern is regulated and to determine the amino acid sequence of the encoded protein. Our studies show that the Cdx-1 gene contains 3 exons and 2 introns and encodes a 268-amino acid protein which is translated from a 1.7-1.8-kilobase mRNA. Transcription of the Cdx-1 gene initiates some 30 base pairs downstream from a typical TATA box which, together with the 5' end of the gene, is located within a CpG island. Transient transfection experiments have shown three regions which regulate Cdx-1 gene expression. These include a typical silencer element at -589 to -380, an element at -887 to -1040 which blocks the effect of the silencer and a positive element at -47 to +66; the only one which shows epithelial cell specificity. Using gel shift and footprinting assays we have detected proteins in nuclear extracts prepared from colonic epithelial cells which bind to the silencer element. These initial results suggest that Cdx-1 gene expression is regulated by multiple positive and negative transcription factors.

Amino Acid Sequence↗
PubMed1993

Fast events in protein folding initiated by nanosecond laser photolysis.

Initiation of protein folding by light can dramatically improve the time resolution of kinetic studies. Here we present an example of an optically triggered folding reaction by using nanosecond photodissociation of the heme-carbon monoxide complex of reduced cytochrome c. The optical trigger is based on the observation that under destabilizing conditions cytochrome c can be unfolded by preferential binding of carbon monoxide to the covalently attached heme group in the unfolded state. Photodissociation of the carbon monoxide thus triggers the folding reaction. We used time-resolved absorption spectroscopy to monitor binding at the heme. Before folding begins we observe transient binding of both nonnative and native ligands from the unfolded polypeptide on a microsecond time scale. Kinetic modeling suggests that the intramolecular binding of methionine-65 and -80 is faster than that of histidine-26 and -33, even though the histidines are closer to the heme. This optical trigger should provide a powerful method for studying chain collapse and secondary structure formation in cytochrome c without any limitations in time resolution.

Amino Acid Sequence↗
PubMed1993

Neurosteroid analogues: structure-activity studies of benz[e]indene modulators of GABAA receptor function. 1. The effect of 6-methyl substitution on the electrophysiological activity of 7-substituted benz[e]indene-3-carbonitriles.

The effect of 6-methyl substitution of the ability of 7-(2-hydroxyethyl)benz[e]indene-3-carbonitriles to potentiate GABA-mediated chloride current and to directly gate a chloride current in the absence of GABA in cultured rat hippocampal neurons was investigated. Structurally analogous steroid 17-carbonitriles that either contained or did not contain a 19-methyl group were also investigated. Compounds were evaluated at 1 microM for their ability to potentiate GABA-mediated currents and at 10 microM for current activation in the absence of GABA. The benz[e]indene 3(R)-carbonitriles and analogous steroid 17 alpha-carbonitriles had no effects in either assay. The benz[e]indene-3(S)-carbonitriles and analogous steroid 17 alpha-carbonitriles were active in both assays. Relative to the 6-unsubstituted benz[e]indene 3(S)-carbonitrile, the following effects of 6-methyl substituents were observed: a 6(a)-methyl group increased both activities; a 6(e)-methyl group decreased both activities; and 6,6-dimethyl substituents had opposing effects so that both activities remained similar to those of the 6-unsubstituted compound. The activities of the steroid 17 beta-carbonitriles were not affected significantly by the presence or absence of a 19-methyl group. A conformational analysis using molecular modeling methods was also performed for the benz[e]indene 3S-carbonitriles and the steroid 17 beta-carbonitriles. The ability of the different 6-methyl substituents to differentially effect the conformations of the flexible benz[e]indenes and the inability of the steroid 19-methyl group to alter the conformations of the rigid steroid 17 beta-carbonitriles are suggested to explain the results.

Androstanols↗
PubMed1993

Isolation and characterization of the binding sequences for the product of the Arabidopsis floral homeotic gene AGAMOUS.

The Arabidopsis floral homeotic gene AGAMOUS (AG) is required for normal flower development. The deduced AG protein contains a region which shares substantial sequence similarity with the DNA-binding domains of known transcription factors, SRF (human) and MCM1 (yeast). Therefore, it is likely that AG is also a DNA-binding protein regulating transcription of floral genes. We describe here several experiments to characterize AG-DNA binding in vitro. We show that AG indeed binds a DNA sequence matching the consensus of SRF targets. Further, we have selected the AG-binding sequences from a pool of random oligonucleotides, and deduced an AG-binding consensus sequence of TT(A/T)CC(A/T)(A/t)2(T/A)NNGG(-G)(A/t)2. We have demonstrated that AG binds to the consensus region of three of the oligonucleotides by footprinting analysis. Finally, we have examined AG's relative binding affinity for different sequences, as compared to SRF, by gel mobility shift analysis. Our results indicate that AG is a sequence-specific DNA-binding protein, and that the AG-binding consensus sequence is similar to those of MCM1 and SRF.

AGAMOUS Protein, Arabidopsis↗
PubMed1993

MyoD and regulation of prostaglandin H synthase.

MM14 myoblasts, in contrast to their differentiation defective variant (DD-1) cells, do not synthesize detectable levels of prostaglandins or of the initial enzyme in the pathway of prostaglandin synthesis, prostaglandin H synthase (PGHS) but do exhibit readily detectable level of PGHS mRNA (Steiner, S., et al., 1991, Exp. Cell Res. 192, 643). These findings suggest a possible relationship between the myogenic phenotype and the synthesis of prostaglandins. This relationship was examined in the current study by analysis of the effect of transfection of DD-1 cells with a MyoD expression vector (termed MyoDD-1 cells) on expression of MyoD and synthesis of prostaglandins. Proliferating MyoDD-1 cells express readily detectable levels of MyoD protein and mRNA and exhibit markedly diminished levels of PGHS protein and prostaglandins. In contrast, serum-deprived MyoDD-1 cells express little MyoD mRNA or protein and exhibit a readily detectable level of PGHS protein despite having only a slightly higher PGHS mRNA abundance compared to growing MyoDD-1 cells. These studies are consistent with the hypothesis that MyoD expression contributes to the inhibition of prostaglandin synthesis.

Animals↗
PubMed1993

Excess mortality among the unmarried: a case study of Japan.

Recent research has demonstrated that mortality patterns by marital status in Japan are different from corresponding patterns in other industrialized countries. Most notably, the magnitude of the excess mortality experienced by single Japanese has been staggering. For example, estimates of life expectancy for the mid-1900s indicate that single Japanese men and women had life expectancies between 15 and 20 years lower than their married counterparts. In addition, gender differences among single Japanese have been smaller than elsewhere, while those among divorced persons have been unanticipatedly large; and, the excess mortality of the Japanese single population has been decreasing over the past few decades in contrast to generally increasing differentials elsewhere. In this paper, we use a variety of data sources to explore several explanations for these unique mortality patterns in Japan. Undeniably, the traditional Japanese system of arranged marriages makes the process of selecting a spouse a significant factor. Evidence from anthropological studies and attitudinal surveys indicates that marriage is likely to have been and probably continues to be more selective with regard to underlying health characteristics in Japan than in other industrialized countries. However, causal explanations related to the importance of marriage and the family in Japanese society may also be responsible for the relatively high mortality experienced by singles and by divorced men.

Cause of Death↗
PubMed1993

Influence of catecholestradiol on short-lived corpora lutea in beef cows.

The influence of intrauterine administration of catecholestradiol (4-hydroxylated estradiol) on lifespan of the initial postpartum corpus luteum was evaluated in suckled beef cows. In experiment 1, postpartum cows (n = 23) were untreated (CONTROL) or received intrauterine infusions (0700 and 1700 hr) of either vehicle (SAL) or catecholestradiol (CATE; 4 micrograms) from day 15 to 22 (day 0 = parturition). Blood samples were collected three times weekly (day 15 to 100) and analyzed for progesterone. In experiment 2, cows received twice daily intrauterine infusions of either vehicle (n = 18), or catecholestradiol (n = 19), from day 25 +/- .5 to day 30 +/- .5. Following the final infusion, calves were temporarily weaned from all cows for 48 hr. At the end of the 48 hr weaning period, cows in each infusion group received either an i.m. injection of 1,000 IU hCG (SAL+hCG, n = 9; CATE+hCG, n = 9) or no further treatment (SAL, n = 9; CATE, n = 10). Blood samples were collected daily for 21 d following calf removal and 3 times weekly through 100 d postpartum. In both experiments, the initial postpartum elevation in peripheral progesterone concentrations was characterized as either a short (< 5 d) or extended (> 8 d) luteal phase. In experiment 1, postpartum anestrous interval (60 +/- 3.4 d) and incidence of short luteal phases (77%) were similar among CONTROL, SAL and CATE treatments. In experiment 2, luteal phases were induced within 10 d of onset of weaning in 90, 100, 56 and 60% of cows in SAL+hCG, CATE+hCG, SAL and CATE treatments, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

5-HT and cAMP induce the formation of coated pits and vesicles and increase the expression of clathrin light chain in sensory neurons of aplysia.

In the course of studying proteins involved in long-term facilitation in Aplysia, we found that 5-HT and cAMP, a second messenger activated by 5-HT, lead to the removal of a set of N-CAM-related cell adhesion molecules (apCAMs) from the surface membrane of sensory neurons by means of receptor-mediated endocytosis. Here we describe that, as part of this coordinated program for endocytosis, 5-HT and cAMP also induce in the sensory neurons an increase in the density of coated pits and coated vesicles and an increase in the expression of the light chain of Aplysia clathrin (apClathrin). The clathrin-related endocytosis seems designed to internalize and redistribute apCAMs and other surface membrane proteins in the sensory neurons, and thus it appears to constitute one of the initial steps in the growth of new synaptic connections that accompanies long-term facilitation.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Marriage selection and age patterns of mortality: a mathematical investigation.

"In this paper, we use simulation models to demonstrate the complexity of the relationship between the marriage selection process and the resulting RMRs [relative mortality ratios]. In particular, we show that marriage selection alone can produce a relative mortality ratio which remains large and relatively constant at ages far beyond the marriage span....Our general objective...is to determine the range of age patterns of relative mortality which could, in theory, result from marriage selection on the basis of health characteristics. We also evaluate the effects of variations in the marriage selection mechanisms on the resulting mortality patterns.... We develop and apply several simple mathematical models of the marriage selection process. In order to distinguish the potential consequences of marriage selection from marriage protection, we consider hypothetical populations in which causal effects are absent.... We begin by considering an extremely simple marriage selection process and subsequently explore a more realistic selection model based on recent death and marriage rates for Japan."

Age Factors↗