Biomedical subjects

Y Wu

Publications and source records attributed to Y Wu.

At least 217 records · Page 12Linked to original sources

PubMed2001

Gender-specific compensation for the lack of NO in the mediation of flow-induced arteriolar dilation.

Flow-induced dilation of gracilis muscle arterioles was examined in both genders of control rats and rats chronically treated with N(omega)-nitro-L-arginine methyl ester (L-NAME). After L-NAME treatment (4 wk), systolic blood pressure was significantly increased compared with control, whereas the plasma concentration of nitrate/nitrite was significantly reduced. Isolated and pressurized arterioles dilated significantly in response to increases in flow (0-25 microl/min). Flow-induced dilation was comparable in arterioles of control and L-NAME-treated rats but was significantly greater in female than in male rats. L-NAME + indomethacin, which abolished flow-induced dilation in arterioles of male control rats, inhibited the dilation by only ~75% in female control rats. The residual portion of the response was eliminated by additional administration of miconazole, an inhibitor of cytochrome P-450. Indomethacin did not affect the dilation in female L-NAME-treated rats but completely inhibited the response in male L-NAME-treated rats. The indomethacin-insensitive, flow-induced dilation in female L-NAME-treated arterioles was abolished by miconazole, 6-(2-proparglyoxyphenyl)hexanoic acid, or charybdotoxin. Thus an augmented release of endothelial prostaglandins accounts for the preserved flow-induced dilation in arterioles of male rats, whereas a metabolite of cytochrome P-450 is responsible for the maintenance of flow-induced dilation in female rats, suggesting important differences in the adaptation of the endothelium of arterioles from male and female rats to the lack of nitric oxide (NO) synthesis.

Animals↗

PubMed2001

Cardiac titin isoforms are coexpressed in the half-sarcomere and extend independently.

Titin, the third myofilament type of cardiac muscle, contains a molecular spring segment that gives rise to passive forces in stretched myocardium and to restoring forces in shortened myocardium. We studied cardiac titin isoforms (N2B and N2BA) that contain length variants of the molecular spring segment. We investigated how coexpression of isoforms takes place at the level of the half-sarcomere, and whether coexpression affects the extensibility of the isoforms. Immunoelectron microscopy was used to study local coexpression of isoforms in a range of species. It was found that the cardiac sarcomere of large mammals coexpresses N2B and N2BA titin isoforms at the level of the half-sarcomere, and that when coexpressed, the isoforms act independently of one another. Coexpressing isoforms at varying ratios results in modulation of the passive mechanical behavior of the sarcomere without impacting other functions of titin and allows for adjustment of the diastolic properties of the myocardium.

Animals↗

PubMed2001

Ventricular hypertrophy amplifies transmural repolarization dispersion and induces early afterdepolarization.

The effects of left ventricular hypertrophy (LVH) on the generation of phase 2 early afterdepolarization (EAD) and transmural dispersion of repolarization (TDR) were assessed using arterially perfused rabbit ventricular wedge preparations. Transmembrane action potentials from epicardium, subendocardium, and endocardium were simultaneously recorded together with a transmural ECG. Transmural action potential duration (APD) was also mapped. LVH (renovascular hypertension model) produced significant prolongation in ventricular APD and QT interval. Preferential APD prolongation in subendocardium and endocardium was associated with a marked increase in TDR. Phase 2 EADs were generated from subendocardium or endocardium in all LVH rabbits (15 of 15) in the absence of APD prolonging agents at basic cycle lengths of 2,000-4,000 ms. Phase 2 EAD could produce "R on T" extrasystoles, initiating polymorphic ventricular tachycardia (VT). This study provides the first direct evidence from intracellular recordings that phase 2 EAD could be generated from rabbit intact hypertrophied LV wall in the absence of APD prolonging agents, resulting in R on T extrasystoles capable of initiating polymorphic VT under enhanced TDR.

Action Potentials↗

PubMed2001

Effect of estrogen on flow-induced dilation in NO deficiency: role of prostaglandins and EDHF.

To investigate the role of estrogen in flow-induced dilation (FiD) in nitric oxide (NO) deficiency, FiD was examined in isolated gracilis arterioles of ovariectomized (OVX) and OVX rats with estrogen replacement (OVE). Both groups of rats were treated chronically with N(omega)-nitro-L-arginine methyl ester. Plasma concentration of NO(2)/NO(3) was reduced in both groups. Plasma concentration of estradiol was lower in OVX than in OVE rats. FiD was similar in vessels of the two groups; calculated wall shear stress and basal tone were significantly greater in OVX vs. OVE rats. Indomethacin did not affect FiD in vessels from OVE rats but abolished dilation in vessels from OVX rats. Valeryl salicylate or NS-398 inhibited FiD by approximately 50%, whereas their simultaneous administration eliminated the response in arterioles from OVX rats. In vessels from OVE rats, miconazole or charybdotoxin eliminated FiD. Thus, in NO deficiency, prostaglandins derived from both cyclooxygenase isoforms mediate FiD in gracilis arterioles of OVX rats. Estrogen replacement switches the mediation, showing dependence on endothelium-derived hyperpolarizing factor in the arterioles of OVE rats.

Animals↗

PubMed2001

Ligands specify coactivator nuclear receptor (NR) box affinity for estrogen receptor subtypes.

Nuclear receptors (NRs) require coactivators to efficiently activate transcription of their target genes. Many coactivators including the p160 proteins utilize a short NR box motif to recognize the ligand-binding domain of the NR when it is activated by ligand. To investigate the ability of various ligands to specify the affinity of NR boxes for a ligand-bound NR, we compared the capacity of p160 NR boxes to be recruited to estrogen receptor (ERalpha) and ERbeta in the presence of 17beta-estradiol, diethylstilbestrol, and genestein. A time-resolved fluorescence-based binding assay was used to determine the dissociation constants for the 10 NR boxes derived from the three p160 coactivators for both ER subtypes in the presence of the each of the agonists. While the affinity of some NR boxes for ER was independent of the agonist, we identified several NR boxes that had significantly different affinities for ER depending on which agonist was bound to the receptor. Therefore, an agonist may specify the affinity of an NR for various NR boxes and thus regulate the coactivator selectivity of the receptor.

Acetyltransferases↗

PubMed2001

Immunomodulating activity of CVT-E002, a proprietary extract from North American ginseng (Panax quinquefolium).

The activity of CVT-E002, an aqueous extract containing mainly oligosaccharides and polysaccharides from North American ginseng (Panax quinquefolium), as an immunobooster on murine spleen cells and peritoneal macrophages, was studied in-vitro. CVT-E002 stimulated the proliferation of normal mouse spleen cells, of which the major responding subpopulation was identified as B lymphocytes. CVT-E002 also activated peritoneal exudate macrophages leading to enhanced interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) production. In addition, CVT-E002 stimulated in-vivo immunoglobulin G (IgG) production in treated mice. These results identify some of the immunomodulating activities of CVT-E002 and suggest its use clinically for the modulation of immune responses.

Adjuvants, Immunologic↗

PubMed2001

Control of oligodendrocyte differentiation by the Nkx2.2 homeodomain transcription factor.

Oligodendrocytes are derived from glial precursors that arise from the ventral neural tube early in development. In the developing chicken CNS, oligodendrocyte progenitors selectively express Nkx2.2 homeodomain transcription factor, raising the possibility that Nkx2.2 may directly regulate oligogliogenesis. In this study, we have examined Nkx2.2 expression in rodent glial precursors and studied the effect of a loss of Nkx2.2 on oligodendrocyte and astrocyte differentiation. We show that Nkx2.2 is also expressed in mammalian oligodendrocyte progenitors and that the differentiation of MBP-positive and PLP-DM20-positive oligodendrocytes is dramatically retarded in Nkx2.2-null mutants along the entire rostrocaudal axis. In contrast, no effect is seen on astrocytic differentiation. Interestingly, absence of Nkx2.2 expression leads to a ventral expansion of the Olig1/Olig2 expression in neuroepithelial cells into the Nkx2.2 domain and a consequent increase in the production of Olig1/Olig2-positive and platelet-derived growth factor receptor alpha-positive oligodendrocyte progenitors. These results strongly suggest that Nkx2.2 regulates the differentiation and/or maturation, but not the initial specification, of oligodendrocyte progenitors. Consistent with this suggestion, overproduction of Nkx2.2 protein in fibroblast cells can induce gene expression from the proteolipid protein promoter.

3T3 Cells↗

PubMed2001

Differences in knowledge, attitude and behavior with respect to hypertension among cardiologists, neurologists and other physicians in internal medicine.

It is known that the knowledge, attitude and behavior (KAB) of physicians with respect to hypertension directly affect the prevention of hypertension and associated cardiovascular diseases. To investigate the differences in KAB among cardiologists, neurologists and other physicians, 1,722 potential participants were selected by stratified random sampling. Among these, 1,609 participants took part in the present survey, and 948 of this group were eligible for the present analysis. The data were collected using a self-administrated questionnaire. Results showed that, with respect to knowledge and attitude regarding hypertension, 15.3% of cardiologists, 15.2% of neurologists and 7.2% of other internals selected the correct answers to all questions (p<0.05). The criteria of hypertension were not correctly understood by about two-thirds of physicians, including both cardiologists and neurologists. With regard to behavior, 16.5% of cardiologists, 17.9% of neurologists and 9.6% of other internals selected the correct answers to all questions (p<0.05). A majority of physicians considered that routine blood pressure measurements were not necessary in cases uncomplicated by cardiovascular disease and other disease, such as nephrotic disease, or diabetes mellitus. One-half to two-thirds of physicians did not believe that life style modifications reduce blood pressure. For each question, cardiologists showed the highest, and other internals the lowest, percentage of correct responses to all items in the questionnaire. These findings indicate that cardiovascular health education must be strengthened for all physicians, and not only for specialists.

Cardiology↗

PubMed2001

Effect of long-term exposure to fluoride in drinking water on risks of bone fractures.

Findings on the risk of bone fractures associated with long-term fluoride exposure from drinking water have been contradictory. The purpose of this study was to determine the prevalence of bone fracture, including hip fracture, in six Chinese populations with water fluoride concentrations ranging from 0.25 to 7.97 parts per million (ppm). A total of 8266 male and female subjects > or =50 years of age were enrolled. Parameters evaluated included fluoride exposure, prevalence of bone fractures, demographics, medical history, physical activity, cigarette smoking, and alcohol consumption. The results confirmed that drinking water was the only major source of fluoride exposure in the study populations. A U-shaped pattern was detected for the relationship between the prevalence of bone fracture and water fluoride level. The prevalence of overall bone fracture was lowest in the population of 1.00-1.06 ppm fluoride in drinking water, which was significantly lower (p < 0.05) than that of the groups exposed to water fluoride levels > or =4.32 and < or =0.34 ppm. The prevalence of hip fractures was highest in the group with the highest water fluoride (4.32-7.97 ppm). The value is significantly higher than the population with 1.00-1.06 ppm water fluoride, which had the lowest prevalence rate. It is concluded that long-term fluoride exposure from drinking water containing > or =4.32 ppm increases the risk of overall fractures as well as hip fractures. Water fluoride levels at 1.00-1.06 ppm decrease the risk of overall fractures relative to negligible fluoride in water; however, there does not appear to be similar protective benefits for the risk of hip fractures.

Aged↗

PubMed2001

Presence of antibody against the inducible Hsp71 in patients with acute heat-induced illness.

Antibodies against heat shock or stress proteins (Hsps) have been reported in a number of diseases in which they may be involved in the pathogenesis of the disease or may be of use for prognosis. Heat-induced diseases, such as heat cramps, heat exhaustion, or heat stroke, are frequent in hot working or living environments. There are still few investigations on the presence and possible significance of autoantibodies against Hsps in heat-induced illnesses. Using an immunoblotting technique with recombinant human Hsps, we analyzed the presence and titers of antibodies against Hsp60, Hsp71, and Hsp90alpha, and Hsp90beta in a group of 42 young male patients who presented with acute heat-induced illness during training. We also examined the presence of antibody against Hsp71 in a second group of 57 patients with acute heat-induced illness and measured the changes in titers of anti-Hsp71 antibodies in 9 patients hospitalized by emergency physicians. In the first group of young persons exercising in a hot environment, the occurrence of antibodies against Hsp71 and Hsp90alpha was significantly higher among individuals with symptoms of heat-induced illness (P < 0.05) than in the matched group of nonaffected exercising individuals. Moreover titers of antibody against Hsp71 were higher in individuals of the severe and mild heat-induced illness groups, the highest titer being found in the most severe cases. The results from the second group of 57 heat-affected patients exposed to extreme heat were similar. Again, patients with the more severe heat-induced symptoms showed a significantly higher incidence of antibodies to Hsp71 than controls and the titer of anti-Hsp71 was higher in the severely affected group. Finally, in a study of 9 patients, it was observed that the titer of anti-Hsp71 decreased during recovery from severe heat symptoms. These results suggest that measurement of antibodies to Hsps may be useful in assessing how individuals are responding to abnormal stress within their living and working environment and may be used as one biomarker to evaluate their susceptibility to heat-induced diseases.

Adolescent↗

PubMed2001

Liver-specific igf-1 gene deletion leads to muscle insulin insensitivity.

Insulin and insulin-like growth factors (IGFs) mediate a variety of signals involved in mammalian development and metabolism. To study the metabolic consequences of IGF-I deficiency, we used the liver IGF-I-deficient (LID) mouse model. The LID mice show a marked reduction (approximately 75%) in circulating IGF-I and elevated growth hormone (GH) levels. Interestingly, LID mice show a fourfold increase in serum insulin levels (2.2 vs. 0.6 ng/ml in control mice) and abnormal glucose clearance after insulin injection. Fasting blood glucose levels and those after a glucose tolerance test were similar between the LID mice and their control littermates. Thus, the high levels of circulating insulin enable the LID mice to maintain normoglycemia in the presence of apparent insulin insensitivity. Insulin-induced autophosphorylation of the insulin receptor and tyrosine phosphorylation of insulin receptor substrate (IRS)-1 were absent in muscle, but were normal in liver and white adipose tissue of the LID mice. In contrast, IGF-I-induced autophosphorylation of its cognate receptor and phosphorylation of IRS-1 were normal in muscle of LID mice. Thus, the insulin insensitivity seen in the LID mice is muscle specific. Recombinant human IGF-I treatment of the LID mice caused a reduction in insulin levels and an increase in insulin sensitivity. Treatment of the LID mice with GH-releasing hormone antagonist, which reduces GH levels, also increased insulin sensitivity. These data provide evidence of the role of circulating IGF-I as an important component of overall insulin action in peripheral tissues.

Animals↗

PubMed2001

t(8;21;8)(p23;q22;q22): a new variant form of t(8;21) translocation in acute myeloblastic leukemia with maturation.

The complex variants of t(8;21) involving chromosomes 8 and 21 as well as a variable chromosome account for 1.1-5% of acute myeloid leukemia (AML) patients. This paper reports a case of AML-M2 with t(8;21;8) translocation for the first time. The patient was a female, aged 47 years. Her myelogram was compatible with AML-M2. Chromosome study using R-banding technique revealed a karyotype 46, XX, t(8;8)(p23;q22). Dual-color FISH assay with two probes P1 164(green signal) and YAC 225B8 (red signal) both of which closely located on the 8q showed that one yellow signal consisting of a green signal and a red signal and one red signal appeared on the long and the short arm of the same der(8) chromosome, respectively, further confirming this translocation occurred between both homologous chromosomes 8. RT-PCR analysis detected the AML1/ETO fusion transcript in our patient, thus indicating that this chromosomal aberration was, in fact, a complex three-way rearrangement t(8;21;8)(p23;q22;q22). In conclusion, combining conventional karyotype, FISH or RT-PCR analyses is a rational strategy for identification of the complex variants of t(8;21) translocation.

Bone Marrow Cells↗

PubMed2001

Functional characteristics of heteromeric Cx40-Cx43 gap junction channel formation.

Cx40:Cx43 expression ratio in A7r5 cells is augmented in growth stimulated vs. growth arrested conditions. To determine the impact of changing Cx40:Cx43 expression ratio on gap junction function, we have developed A7r5 cell lines that display Cx40:Cx43 ratios of 1:1 (66B5n) and 10:1 (A7r540C3). When Rin43 cells were paired with these coexpressing cells, there was an increasing asymmetry of voltage dependent gating as the Cx40:Cx43 ratio increased in the coexpressing cell. This asymmetry was opposite to that which is predicted by Cx40/Cx43 heterotypic channels. In addition, when Rin43 cells were paired with coexpressing cells there was a shift toward smaller single channel event amplitudes with increasing Cx40:Cx43 ratio in the coexpressing cell. Again, this is opposite to that which is predicted by Cx40/Cx43 heterotypic channels. In dye coupling experiments, 6B5N, A7r5, and A7r540C3 cells displayed charge and size selectivity that increased with increasing Cx40:Cx43 expression ratio. These data indicate that although the electrophysiological properties of heteromeric/heterotypic channels are not directly related to the proportions of Cx constituents that comprise the channel, the dye permeability data fit what would be predicted by an increase in Cx40:Cx43 ratio.

Animals↗

PubMed2001

Kinetic analysis of a simplified scheme of autocatalytic zymogen activation.

Proteolytic enzymes are usually biosynthesized as somewhat larger inactive precursors known as zymogens. These zymogens must undergo an activation process, usually a limited proteolysis, to attain their catalytic activity. When the activating enzyme and the activated enzyme coincide, the process is an autocatalytic zymogen activation. In the present study, a kinetic analysis of the entire progress curve for the autocatalytic zymogen activation reactions is presented. On the basis of the kinetic equations, a novel procedure is developed to evaluate the kinetic parameters of the reactions. This procedure is particularly useful for the fast zymogen autoactivation reactions. As two examples, the novel procedure is used to analyse the autocatalytic activation of bovine trypsinogen and human blood coagulation factor XII (Hageman factor).

Animals↗

PubMed2001

Solution structure of cytochrome b(5) mutant (E44/48/56A/D60A) and its interaction with cytochrome c.

Using 1617 meaningful NOEs with 188 pseudocontact shifts, a family of 35 conformers of oxidized bovine microsomal cytochrome b5 mutant (E44/48/56A/D60A) has been obtained and is characterized by good resolution (rmsd to the mean structure are 0.047 +/- 0.007 nm and 0.095 +/- 0.008 nm for backbone and heavy atoms, respectively). The solution structure of the mutant, when compared with the X-ray structure of wild-type cytochrome b(5), has no significant changes in the whole folding and secondary structure. The binding between cytochrome b(5) and cytochrome c shows that the association constant of the mutant-cytochrome c complex is much lower than the one for wild-type complex (2.2 x 10(4) M(-1) vs. 5.1 x 10(3) M(-1)). The result suggests the four acidic residues have substantial effects on the formation of the complex between cytochrome b(5) and cytochrome c, and therefore it is concluded reasonably that the electrostatic interaction plays an important role in maintaining the stability and specificity of the complex formed. The competition between the ferricytochrome b(5) mutant and [Cr(oxalate)(3)](3-) for ferricytochrome c shows that site III of cytochrome c, which is a strong binding site to wild-type cytochrome b(5), still binds to the mutant with relatively weaker strength. Our results indicate that certain bonding geometries do occur in the interaction between the present mutant and cytochrome c and these geometries, which should be quite different from the ones of the Salemme and Northrup models.

Amino Acid Sequence↗

PubMed2001

[Expression of tumor suppressor genes p16, p21 and p53 in a pair of lung adenocarcinoma cell lines with different metastasis potentials: Anip973 and AGZY83-a].

OBJECTIVE: In order to investigate the suppression effect of tumor suppressor genes in lung adenocarcinoma. METHODS: p16 and p21 expression vectors were transfected into a pair of lung adenocarcinoma cell lines with different metastasis potentials: Anip973(high metastasis potential)and AGZY83-a (low metastasis potential). In the mean time, AGZY83-a, Anip973, AGZY83-ap16 and Anip973p16 were infected with recombinant adenovirus encoding wild- type p53 gene. The suppression effects of these genes were evaluated by cell growth curve, MTT, cloning efficiency assay, flow cytometric analysis and TUNEL technique. RESULTS: Overexpression of p16 gene in Anip973 and AGZY83-a could only lengthen the G(1) phase while increased expression of p21 in both of the cell lines was associated with significant lengthening of G(1) phase, decreased proliferation potential and decreased cloning efficiency. High efficient expression of wild-type p53 gene in AGZY83-a, Anip973, Anip973p16 and AGZY83-ap16 inhibited the growth of these four kinds of lung cancer cells and killed the cells in the end. Apoptosis was detected in all the four kinds of cells. The suppression effect of p53 gene was higher in Anip973 and Anip973p16 than in AGZY83-a and AGZY83-ap16 while co-expression of p53 and p16 in this pair of cell lines inhibited the cells more efficiently as compared with the expression of p53 gene. CONCLUSION: Increased expression of p21 gene suppressed the lung adenocarcinoma cells by G(1) arrest and the co-transfection of tumor suppressor genes p16 and p53 into the lung adenocarcinoma cell line proved more effective in lung cancer gene therapy.

Adenocarcinoma↗

PubMed2001

[Non-invasive prenatal diagnosis of Duchenne muscular dystrophy].

OBJECTIVE: This paper was designed to investigate the feasibility of non-invasive prenatal diagnosis of Duchenne muscular dystrophy(DMD). METHODS: The nucleated red blood cells(NRBC) were separated with percoll using a discontinuous density gradient method. The cells were smeared on microscope slides using a cyto-centrifuge and then stained by Wright- Giemsa. NRBCs were detected and individually retrieved into glass capillary pipettes using a micromanipulator under microscopic observation. The whole genome of a single cell was amplified by improved primer extension preamplification(PEP). The procedures for making prenatal diagnosis of DMD and determining the origin of NRBCs proceeded at the same time using sex determination and linkage analysis of several STR loci of dystrophin. Genotypes were analyzed by amplifying the 9 STR fragments using fluorescence-PCR technique and NRBCs origin was further determined. RESULTS: A case of DMD in male fetus was diagnosed. CONCLUSION: With the use of the method reported, the non-invasive prenatal diagnosis of DMD is possible.

Female↗

PubMed2001

[Identification of traditional Chinese medicine Baizhi with near-infrared spectrum].

In this paper, 8 kinds of traditional Chinese medicines Baizhi were identified by near-infrared spectrum, coping with pattern recognition. The results showed that near-infrared spectrum method in identifying traditional Chinese medicines Baizhi was not only simple, rapid, but also using few examples, noninvasion. This method provided referential information for identifying these traditional Chinese medicines.

Angelica↗