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Biomedical subjects

H Cao

Publications and source records attributed to H Cao.

At least 145 records · Page 8Linked to original sources
PubMed1999

[The study on cytomegalovirus infection associated with vascular complications in patients with essential hypertension].

OBJECTIVE: This paper studied HCMV infection inpatients with essential hypertension and the relationship of HCMV infection with vascular complications. METHODS: Indirect ELISA method was used to detect human cytomegalovirus (HCMV) specific antibodies in sera of 105 patients with essential hypertension. RESULTS: The results showed that the positive rates of active HCMV-IgM and IgA antibodies were 26.67% and 20.95%, respectively, higher than that of the control group (6.67%). The positive rate of HCMV active IgM antibody in III stage group was significantly higher than that of I + II stage groups (P < 0.01). Active HCMV infective rate was higher in patients with vascular complication. CONCLUSION: These results suggested that HCMV active infection may be associated with vascular complication.

Adult↗
PubMed1999

[A comparison of Fe, Zn, Cu, Cr, Cd and Pb concentration in serum determined by ICP-AES using different sample preparation procedures].

Fe, Zn, Cu, Cr, Cd and Pb concentrations in serum of 21 arteriosclerosis (AS) and 18 healthy control (CK) were determined by ICP-AES, and sample solution was prepared using acid digestion (Dig.) and acid dilution (Dil.) procedure. Serum total Fe, Zn and Cr were significantly higher using Dig. than that using Dil. Serum Cu and Pb were of no significant differences using the both procedures. Serum Cd was significantly lower using Dig. than that using Dil. The results of Fe, Cu, Zn and Cr were positively correlated between Dig. and Dil., but those of Pb and Cd were of no significant correlation. Six elements concentrations in serum determined were significantly different between AS and CK using Dig. The digestion procedure was recommended for serum trace elements analysis using ICP-AES.

Case-Control Studies↗
PubMed1999

Paraoxonase protection of LDL against peroxidation is independent of its esterase activity towards paraoxon and is unaffected by the Q-->R genetic polymorphism.

High density lipoprotein (HDL)-associated paraoxonase (PON) seems to play a major role in the protection of low density lipoprotein (LDL) against peroxidation by HDL, and the partly purified enzyme exerts a dose-dependent protective effect. A common polymorphism of the human gene (192 Q-->R) modulates paraoxonase activity but purified enzyme from either genotype is equally effective against LDL peroxidation. The inhibition of Cu2+-induced LDL peroxidation by HDL was monitored by lipid peroxide assay and change in LDL electrophoretic mobility. We show that HDL from type 2 diabetic patients with the QQ or RR genotype (n = 12 for each) reduce, to the same extent, both peroxide production (by 60.6 +/- 20.0 and 63.9 +/- 23.5%) and relative change in mobility (61.3 +/- 21.8 and 61.4 +/- 26.5%) despite a 6-fold difference in paraoxonase activity (47.4 +/- 4.4 vs. 299.7 +/- 23.7 U/l, P < 0.0001). Protection was, however, related to paraoxonase activity, but with a different efficiency in each group corresponding to a better protection per unit of enzyme in the QQ genotype group. Inactivation of PON activity by heating (56 degreesC, 10 min) or by EDTA was totally without effect on protection, which remained correlated with the paraoxonase activity measured prior to inactivation. In summary, these results suggest that the protein bearing both paraoxonase and arylesterase activities also possesses a third thermostable property, closely associated with paraoxon hydrolysis activity and unaffected by PON genetic variability.

Aryldialkylphosphatase↗
PubMed1998

Cloning and characterization of a novel transforming growth factor-beta1-induced TIAF1 protein that inhibits tumor necrosis factor cytotoxicity.

To determine how TGF-beta1 protects L929 fibroblasts against TNF-alpha cytotoxicity, we report the isolation and characterization of a novel cDNA encoding a 12-kDa TGF-beta1-induced antiapoptotic factor, designated TIAF1. GFP-tagged TIAF1 protein is present mostly in perinuclear and nuclear locations. TIAF1 inhibits the cytotoxic effects of TNF-alpha and overexpressed TNF receptor adaptors TRADD, FADD, and RIP. L929 stable transfectants expressing TIAF1 do not have significant changes in the expression of TNF receptors and effector or regulatory proteins in apoptosis, which may account for the acquired TNF resistance in these cells. Notably, these cells have a significantly suppressed IkappaB-alpha protein expression, and IkappaB-alpha degradation is blocked when exposing these cells to TNF-alpha. Similarly, stimulation of untransfected L929 cells with TGF-beta1 results in suppression of IkappaB-alpha expression and retarded IkappaB-alpha degradation in response to TNF-alpha. Despite the fact that the mechanism for blocking TNF cytotoxicity is unknown, TIAF1 is apparently involved in TGF-beta1 inhibition of IkappaB-alpha expression and suppression of TNF-mediated IkappaB-alpha degradation.

Amino Acid Sequence↗
PubMed1998

TGGA repeats impair nucleosome formation.

Nucleosomes, the building blocks of chromatin, are responsible for DNA packaging in eukaryotic cell nuclei. They play a structural role in genome condensation, and influence transcription and replication. Properties of the DNA sequence, such as curvature and flexibility, direct the location of nucleosomes. DNA sequences that position nucleosomes have been identified and rules that govern their properties have been formulated. However, DNA sequences that are refractory to nucleosome formation have been less well characterised and it is possible that they may perturb or alter chromatin structure. Here we identify such sequences by selecting those that refrain from nucleosome formation from a large pool of synthetic DNA fragments with a central region of 146 random base-pairs fitted with adapters for PCR amplification. These were used for in vitro salt-induced reconstitution of nucleosomes under thermodynamic equilibrium conditions. Fragments that did not form nucleosomes were purified, amplified by PCR, and the reconstitution was repeated. After 17 rounds of negative selection, the material was highly enriched in sequences reluctant to form nucleosomes. Cloning and sequencing revealed that 35% of the molecules had long repeats of TGGA, and their affinity for histone octamers was about half that of average DNA.

Animals↗
PubMed1998

Generation of broad-spectrum disease resistance by overexpression of an essential regulatory gene in systemic acquired resistance.

The recently cloned NPR1 gene of Arabidopsis thaliana is a key regulator of acquired resistance responses. Upon induction, NPR1 expression is elevated and the NPR1 protein is activated, in turn inducing expression of a battery of downstream pathogenesis-related genes. In this study, we found that NPR1 confers resistance to the pathogens Pseudomonas syringae and Peronospora parasitica in a dosage-dependent fashion. Overexpression of NPR1 leads to enhanced resistance with no obvious detrimental effect on the plants. Thus, for the first time, a single gene is shown to be a workable target for genetic engineering of nonspecific resistance in plants.

Journal Article↗
PubMed1998

Role of dynamin in the formation of transport vesicles from the trans-Golgi network.

Dynamin guanosine triphosphatases support the scission of clathrin-coated vesicles from the plasmalemma during endocytosis. By fluorescence microscopy of cultured rat hepatocytes, a green fluorescent protein-dynamin II fusion protein localized with clathrin-coated vesicles at the Golgi complex. A cell-free assay was utilized to demonstrate the role of dynamin in vesicle formation at the trans-Golgi. Addition of peptide-specific anti-dynamin antibodies to the assay mixture inhibited both constitutive exocytic and clathrin-coated vesicle formation. Immunodepletion of dynamin proteins also inhibited vesicle formation, and budding efficiency was restored upon readdition of purified dynamin. These data suggest that dynamin participates in the formation of distinct transport vesicles from the trans-Golgi network.

Adenosine Triphosphate↗
PubMed1998

Lack of association between carotid intima-media thickness and paraoxonase gene polymorphism in non-insulin dependent diabetes mellitus.

Paraoxonase (PON) is an HDL-bound enzyme capable of hydrolyzing lipid peroxides and believed to be in part responsible for the protective effect of HDL against LDL oxidation. Its activity is mainly determined by a gene polymorphism of the PON 1 gene (Glu-Arg 192). Low activity has been related to an elevated incidence of myocardial infarction. In several case-control studies, however, the high activity B allele is paradoxically more prevalent in patients. We have re-investigated this relationship, using carotid intima-media thickness (IMT) as a surrogate continuous variable for macroangiopathy. Genotypes were determined in 197 non insulin-dependent diabetic patients (HbAlc 8.8+/-0.15%, BMI 28.3+/-0.36). IMT, measured by high resolution mode B ultrasound, was the same for all genotypes (AA: 0.83+/-.013, AB 0.82+/-.017 and BB: 0.81+/-.034 mm). Bearers of the B allele displayed higher Lp(a) concentration (AA: 197+/-28, AB: 221+/-26, BB: 225+/-45 mg/l, P=0.024) with a significant linear trend (P < 0.005). Multiple regression showed age and systolic blood pressure, but not Lp(a), to be the main determinants of IMT variability without the contribution of the PON genotype. No consistent differences could be found between genotypes in the peroxidizability of LDL (lag-time, rate of diene production and maximal concentration). Our data support the view that there is no association between the early changes of atherosclerosis as defined by carotid IMT and variation in codon 192 of PON 1.

Age Factors↗
PubMed1998

Differential distribution of dynamin isoforms in mammalian cells.

Dynamins are 100-kDa GTPases that are essential for clathrin-coated vesicle formation during receptor-mediated endocytosis. To date, three different dynamin genes have been identified, with each gene expressing at least four different alternatively spliced forms. Currently, it is unclear whether these different dynamin gene products perform distinct or redundant cellular functions. Therefore, the focus of this study was to identify additional spliced variants of dynamin from rat tissues and to define the distribution of the dynamin family members in a cultured rat epithelial cell model (Clone 9 cells). After long-distance reverse transcription (RT)-PCR of mRNA from different rat tissues, the full-length cDNAs encoding the different dynamin isoforms were sequenced and revealed four additional spliced variants for dynamin I and nine for dynamin III. Thus, in rat tissues there are a total of at least 25 different mRNAs produced from the three dynamin genes. Subsequently, we generated stably transfected Clone 9 cells expressing full-length cDNAs of six different spliced forms tagged with green fluorescent protein. Confocal or fluorescence microscopy of these transfected cells revealed that many of the dynamin proteins associate with distinct membrane compartments, which include clathrin-coated pits at the plasma membrane and the Golgi apparatus, and several undefined vesicle populations. These results indicate that the dynamin family is more extensive than was originally predicted and suggest that the different dynamin proteins are localized to distinct cytoplasmic or membrane compartments.

Amino Acid Sequence↗
PubMed1998

Brittle-1, an adenylate translocator, facilitates transfer of extraplastidial synthesized ADP--glucose into amyloplasts of maize endosperms.

Amyloplasts of starchy tissues such as those of maize (Zea mays L.) function in the synthesis and accumulation of starch during kernel development. ADP-glucose pyrophosphorylase (AGPase) is known to be located in chloroplasts, and for many years it was generally accepted that AGPase was also localized in amyloplasts of starchy tissues. Recent aqueous fractionation of young maize endosperm led to the conclusion that 95% of the cellular AGPase was extraplastidial, but immunolocalization studies at the electron- and light-microscopic levels supported the conclusion that maize endosperm AGPase was localized in the amyloplasts. We report the results of two nonaqueous procedures that provide evidence that in maize endosperms in the linear phase of starch accumulation, 90% or more of the cellular AGPase is extraplastidial. We also provide evidence that the brittle-1 protein (BT1), an adenylate translocator with a KTGGL motif common to the ADP-glucose-binding site of starch synthases and bacterial glycogen synthases, functions in the transfer of ADP-glucose into the amyloplast stroma. The importance of the BT1 translocator in starch accumulation in maize endosperms is demonstrated by the severely reduced starch content in bt1 mutant kernels.

Adenosine Diphosphate Glucose↗
PubMed1998

99mTc-labelled red blood cell scintigraphy for localization of gastrointestinal bleeding in chronic renal failure.

Angiodysplasia (AD) may be the source of bleeding in patients with gastrointestinal hemorrhage, with special occurrence in the elderly population and in patients with chronic renal failure (CRF). Although several techniques have been tested for its diagnosis, the gold standard is not well defined yet. We analyze the usefulness of 99mTc-labelled red blood cell (99mTc RBC) scintigraphy in the localization of bleeding from AD lesions in a cohort of 21 patients. Other investigative methods include fibrocolonoscopy examination, angiography, or diagnostic laparotomy. Group A (AD and CRF): 11 patients. Group B (AD without CRF): 10 patients. 99mTc RBC scintigraphy showed 88.9% sensitivity and specificity in group A, while in group B it had 100% sensitivity and specificity. Arteriography showed 100% sensitivity and specificity. On the contrary, fibrocolonoscopy had a very low sensitivity (30%). Our results suggest that 99mTc RBC scintigraphy may be the preferred diagnostic tool for AD, especially in patients with CRF, in whom arteriography may accelerate the decline of renal function.

Aged↗
PubMed1998

G protein beta3 subunit gene variant and blood pressure variation in Canadian Oji-Cree.

The subunits of the heterotrimeric G proteins are attractive candidate gene products for both susceptibility to essential hypertension and interindividual variation in blood pressure. There is alternative splicing of exon 9 of the gene encoding the beta3 subunit of heterotrimeric G proteins (GNB3) associated with a C-->T change at nucleotide 825, which activates a cryptic splice site. The 825T allele results in a gene product that is 41 amino acids smaller than the wild-type gene product. G protein heterotrimers containing the shorter variant are more reactive than those containing the wild type, and the 825T allele appears to be associated with essential hypertension. To evaluate whether this variant is associated with hypertension or blood pressure in other human samples, we genotyped 447 young adult Oji-Cree for the GNB3 C825T variation. We found that the frequency of the GNB3 825T allele was 0.501 in the Oji-Cree, which is considerably higher than the frequency observed in whites. Furthermore, genetic variation of the GNB3 nucleotide 825 was significantly associated with variation in systolic pressure but not diastolic pressure. Specifically, subjects with the 825T/T genotype had significantly lower systolic pressure than subjects with the 825C/T and 825C/C genotypes; the association was independent of sex. Furthermore, the 825T allele frequency tended to be higher in subjects who took antihypertensive medications than in subjects who did not (0.571 versus 0.496; P=NS), although this young sample had relatively few subjects with hypertension. The findings support an association of variation in this gene with variation in blood pressure.

Adolescent↗
PubMed1998

Variation in the AU(AT)-rich element within the 3'-untranslated region of PPP1R3 is associated with variation in plasma glucose in aboriginal Canadians.

We are investigating associations between variations in candidate genes on chromosome 7q and diabetes-related phenotypes in Canadian Oji-Cree. One of these genes encodes the skeletal muscle regulatory G subunit of the glycogen-associated form of protein phosphatase 1 (PPPIR3), which may play a key role in muscle glycogen metabolism. There is a common 5-bp insertion-deletion polymorphism in a messenger ribonucleic acid-stabilizing AU(AT)-rich element within the 3'-untranslated region (UTR) of PPPIR3. The D allele had a frequency of 0.30 in the Oji-Cree. We found that this 3'-UTR variation of PPPIR3 was significantly associated with variation in 2-h postprandial glucose in adult Oji-Cree with type 2 diabetes or impaired glucose tolerance (IGT). Specifically, Oji-Cree with diabetes or IGT who were D/D homozygotes had significantly lower 2-h postprandial plasma glucose than subjects with the other genotypes. There was no association of the PPPIR3 genotype either with the presence of type 2 diabetes or IGT or with other quantitative traits in this sample. These findings suggest that common PPPIR3 3'-UTR variation that potentially affects messenger ribonucleic acid stability is associated with variation in glycemia in Oji-Cree subjects with type 2 diabetes.

3' Untranslated Regions↗
PubMed1998

[Fas mediated apoptosis inhibited by human bcl-2 gene in lymphoma cell line Jurkat].

OBJECTIVE: To understand the mechanism of bcl-2 gene in escaping the immune surveillance in the development of lymphoma. METHODS: A recombinant retroviral vector pLXSN-bcl-2 was constructed by cloning bcl-2 cDNA into the replication defective retroviral vector pLXSN, and transferred to packaging cell line PA317 by electroporation. The G418 resistant colonies were selected, and the supernatants of the colony cultures were used to infect the human lymphoma cell line Jurkat. Cells in G418 resistant Jurkat colonies were characterized by immunohistochemistry. Anti-Fas monoclonal antibody (McAb) was applied to Jurkat cells for inducing apoptosis which mimicked the cytotoxic activity of T lymphocyte. RESULTS: Expression of bcl-2 in pLXSN-bcl-2 transfected Jurkat cell (Jurkat-bcl-2) increased, while there was no change of Fas gene expression. Apoptosis was blocked in Jurkat-bcl-2 by anti-Fas McAb treatment. CONCLUSION: Overexpression of bcl-2 in lymphoma cell line could inhibit cell apoptosis induced by anti Fas McAb, suggesting that overexpression of bcl-2 is one of the mechanisms in escaping immune surveillance in the development of lymphoma.

Apoptosis↗
PubMed1998

Effect of crystalloid cardioplegic solution at different calcium concentration on immature myocardium.

OBJECTIVE: To determine the myocardial protective effect of crystalloid cardioplegic solution at different calcium concentration on immature myocardium. METHODS: Isolated perfused neonatal rabbit hearts from three groups, arrested by intermittent infusion of St. Thomas II cardioplegic solution with different concentration of calcium (in each group, only calcium concentration of cardioplegic solution was modified, I. [Ca2+] 0.6 mmol/L; II. [Ca2+] 1.2 mmol/L; III. [Ca2+] 2.4 mmol/L), were kept ischemic globally at 20 degrees C for 90 minutes and then followed by 30 minutes of reperfusion in Langendorff mode. RESULTS: Although the recovery of LVDP, +dp/dtmax at calcium content of 2.4 mmol/L after 10 minutes of reperfusion was significantly higher than those at 0.6 and 1.2 mmol/L calcium (P < 0.05, P < 0.01, respectively). The declined tendency of left ventricular hemodynamics after 20 minutes of reperfusion in this group was detected. By the end of reperfusion, the left ventricular functional recovery at 2.4 mmol/L calcium did not differ from those at 1.2 and 0.6 mmol/L calcium. Conversely, postischemic left ventricular functions at 0.6 and 1.2 mmol/L calcium were gradually improved during 30 minutes of reperfusion. In 2.4 mmol/L calcium group, the Ca(2+)-ATPase activity significantly increased (P < 0.01, P < 0.001) whereas myocardial ATP content was lower when compared with 1.2 mmol/L (P < 0.001) and 0.6 mmol/L calcium groups. CONCLUSIONS: Our research demonstrated that there were no statistical differences with respect to hemodynamic recovery in three groups after 30 minutes of reperfusion although left ventricular functional recovery at 2.4 mmol/L calcium accelerated early after reperfusion. In addition, with 2.4 mmol/L calcium, myocardial ATP content was decreased significantly. We conclude that, from the point of view of myocardial energy metabolism, St. Thomas II cardioplegic solution at high concentration of calcium can not provide immature myocardium with optimal myocardial protection while with 1.2 mmol/L calcium, however, better high-energy store can be preserved.

Animals↗
PubMed1998

Mechanism of overproduction of plasma prostacyclin in portal hypertensive rats.

OBJECTIVE: To evaluate the role of increased portal pressure and portosystemic shunting in elevated level of prostacyclin (PGI2) in portal hypertension. METHODS: Thirty-six male Sprague-Dawley rats were divided into four groups: prehepatic portal hypertension (PHPH, 8 rats), intrahepatic portal hypertension (IHPH, 9), end-to-side portacaval shunt (PCS, 8), and sham-operated controls (SO, 11). Two weeks after surgery, free portal pressure (FPP) was measured; systemic and splanchnic hemodynamics was studied by radioactive microsphere technique and blood sample from the femoral artery was obtained to measure the level of plasma 6-keto-PGF1 alpha with radioimmunoassay. RESULTS: The FPP (mmHg) in IHPH, PHPH, PCS and SO rats was 13.10 +/- 1.02, 12.10 +/- 1.52, 3.0 +/- 0.82 and 6.86 +/- 0.69, respectively. The value of FPP was significantly increased in IHPH, PHPH rats and significantly decreased in PCS rats when compared to SO rats. Cardiac index (CI) and portal venous inflow (PVI) were in the order of PCS > PHPH > IHPH > SO rats. Portosystemic shunting (PSS) in PCS, PHPH, IHPH was 99.7 +/- 0.29%, 76.02 +/- 20.62% and 30.34 +/- 10.18%, respectively. The concentrations of plasma 6-keto-PGF1 alpha (ng/ml) in PHPH, IHPH, PCS and SO rats were 6.93 +/- 2.43, 5.09 +/- 2.27, 2.36 +/- 1.01 and 1.56 +/- 0.61, respectively. The concentrations of plasma PGI2 in PHPH, IHPH and PCS rats were significantly higher than those in SO rats. Furthermore, the concentrations of plasma PGI2 in PHPH and IHPH rats were also significantly higher than those in PCS rats. Moreover, a closed positive correlation existed between plasma PGI2 and FPP (r = 0.67, P < 0.001). CONCLUSIONS: The results of the present study suggest that the elevated PGI2 in portal hypertension is mainly due to the overproduction of PGI2 in vascular epithelium cells induced by increased portal pressure, whereas portosystemic shunting and liver dysfunction play a secondary role. In addition, the results of this study do not support that PGI2 mediated the hyperhemodynamics in portal hypertension.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

[Comparative study on effect of Panax notoginseng and ticlid in treating early diabetic nephropathy].

OBJECTIVE: To explore the ameliorative effect and mechanism of Panax notoginseng (PNG) and ticlid in treating early diabetic nephropathy (DN). METHODS: Fifty-eight patients were divided randomly into two groups, 28 patients of the ticlid group treated with ticlid 250 mg orally, once a day and 30 patients of the PNG group treated with PNG 8 ml in 250 ml of normal saline intravenous drip once a day. The therapeutic effect and relative indexes of the two groups were observed and compared. RESULTS: After treatment, in both groups, the thromboxane B2 markedly reduced and was more prominent in the ticlid group (P < 0.05), while the 6-keto-prostaglandin F1 alpha increased obviously, so as to cause a significant lowering of T/K ratio, P < 0.01. Levels of urinary albumin, beta 2 microglobulin and blood alpha 1 microglobulin of both groups were lowered significantly, P < 0.01. A significant positive linear correlation was found in the ticlid group between urinary albumin and T/K ratio (r = 0.41, P < 0.01), as well as in blood alpha 1 microglobulin with T/K ratio (r = 0.34, P < 0.05), while it was not found in the PNG group. CONCLUSION: Ticlid and PNG were beneficial to resume the balance of T/K and improve microcirculation, reduce whole blood viscosity and decrease urinary albumin so as to retard the progress of DN.

6-Ketoprostaglandin F1 alpha↗