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G Cao

Publications and source records attributed to G Cao.

At least 145 records · Page 8Linked to original sources
PubMed1995

[Synthesis of S(+)-2-(4-isobutylphenyl) propionic acid by asymmetric hydrolysis of microbial enzyme. II. Reaction conditions and product extraction].

Trichosporon cutaneum 158 exhibited higher sterospecificity to hydrolyze substrate ibuprofen ester. Among the five chosen substrate, asymmetric hydrolysis of methyl ester or isopropyl ester formed S(+)-ibuprofen of 97% ee. While ethyl ester not only gave ee 93% but also showed the highest hydrolytic activity. The optimum pH range for asymmetric hydrolysis was 6.5-7.0. Ability of resolusion was stabler in the range of temperature 28-37 degrees C. This yeast produced intracellular enzyme. Hydrolysis can be carried out by powered cells treated by iced-acetone to improve the specificity of resolution. The product S(+)-ibuprofen can be got with acid-base reaction and organic solvent extraction, unreacted esters can be recovered simultaneously.

Hydrolysis↗
PubMed1995

Automated assay of oxygen radical absorbance capacity with the COBAS FARA II.

Reactive oxygen species are of interest in biology and medicine because of evidence relating them to aging and disease processes. A relatively simple but sensitive and reliable method for quantifying the oxygen radical absorbance capacity (ORAC) of antioxidants in biological tissues has been automated for use with the COBAS FARA II centrifugal analyzer with a fluorescence-measuring attachment. In this assay, beta-phycoerythrin (beta-PE) is used as an indicator protein, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a peroxyl radical generator, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) as a calibrator for antioxidant activity. This assay is unique because the reaction goes to completion so that both inhibition time and inhibition degree are considered in quantifying ORAC (micromoles of Trolox equivalent per liter or per gram of tissue). This method can be used not only for serum but also other tissue and food samples and is suitable for application to a range of nutritional and clinical conditions.

Animals↗
PubMed1995

[Comparative study of ultrasonic detection of popliteal vein reflux].

The venous valve undergoes more destruction and malfunction, and the quantity and duration of venous valvular reflux are larger and longer. On the basis of this mechanism, we detected the popliteal vein reflux duration and various influencing factors with duplex ultrasound. The reflux duration longer than 0.5 secand was verified as the evidence of primary venous insufficiency (PVI) in the detection of 40 cases. The detecting method recommended by us is that with standing position, and pneumatic compression 10. 67kPa (80mmHg) applied to calf, the reflux duration through popliteal venous valves is detected by using both pulsed-wave Doppler scanning and color-flow Doppler scanning. With the rates of sensitivity (92%), specificity (100%), and accuracy (94%), this noninvasive, quantitative, and easily handled method showed a very good diagnostic value.

Aged↗
PubMed1994

Synergistic insertion of two hydrophobic regions drives Sec-independent membrane protein assembly.

We have studied the membrane insertion of two proteins from the inner membrane of Escherichia coli, both with two transmembrane segments connected by a short periplasmic loop: the M13 procoat protein and a mutant "inverted" leader peptidase. Neither molecule depends on the Sec machinery for insertion. We show that the introduction of a charged residue in the second transmembrane segment completely blocks insertion of both proteins. In contrast, a Sec-dependent procoat mutant, where the periplasmic region has been lengthened, inserts into the membrane even in the presence of a charged residue in the second hydrophobic domain. In addition, a large deletion within the second transmembrane domain of the leader peptidase mutant allows membrane translocation, but only under conditions where the SecA protein is functional. Furthermore, we show that the first hydrophobic domain is required for insertion of the short periplasmic loop of the "inverted" leader peptidase. These results suggest that Sec-independent insertion occurs by a synergistic entry of the two neighboring hydrophobic domains into the lipid bilayer.

Bacterial Proteins↗
PubMed1994

Translocation of N-terminal tails across the plasma membrane.

Previously we have shown that the first hydrophobic domain of leader peptidase (lep) can function to translocate a short N-terminal 18 residue antigenic peptide from the phage Pf3 coat protein across the plasma membrane of Escherichia coli. We have now examined the mechanism of insertion of N-terminal periplasmic tails and have defined the features needed to translocate these regions. We find that short tails of up to 38 residues are efficiently translocated in a SecA- and SecY-independent manner while longer tails are very poorly inserted. Efficient translocation of a 138 residue tail is restored and is Sec-dependent by the addition of a leader sequence to the N-terminus of the protein. We also find that while there is no amphiphilic helix requirement for N-terminal translocation, there is a charge requirement that is needed within the tail; an arginine and lysine residue can inhibit or completely block translocation when introduced into the tail region. Intriguingly, the membrane potential is required for insertion of a 38 residue tail but not for a 23 residue tail.

Adenosine Triphosphatases↗
PubMed1994

Familial aggregation of cardiovascular diseases in African-American pedigrees.

Familial aggregation of cardiovascular diseases and diabetes has been consistently demonstrated. However, virtually all of the evidence on the familial patterns of these diseases has come from white population samples. This study evaluates the level of familial excess risk among first degree relatives of 232 African-American pedigrees which included 1,420 individuals recruited from the Chicago, IL, area. Excess disease risk was observed among relatives (parents and offsprings) of affected probands compared to relatives of unaffected probands for coronary heart disease (odds ratio [OR] = 5.30; 95% confidence interval [CI] = 2.51-11.23); hypertension (OR = 1.98; CI = 1.41-2.80); stroke (OR = 3.24; CI = 1.08-9.70); and diabetes (OR = 2.95; CI = 1.55-5.62). The results of this study clearly show that coronary heart disease, hypertension, stroke, and diabetes aggregate in some African-American families and not others. Unaffected relatives of persons suffering from these diseases should be encouraged to have their blood pressure, lipid, and blood glucose levels measured at frequent intervals. These recommendations are particularly urgent in African-American communities because of the disproportionately high morbidity and mortality experienced from cardiovascular diseases and diabetes.

Adult↗
PubMed1993

Determinants of incident non-insulin-dependent diabetes mellitus among blacks and whites in a national sample. The NHANES I Epidemiologic Follow-up Study.

The excess incidence of non-insulin-dependent diabetes mellitus noted among African Americans in the past two decades may be attributable to variations in the distribution of specific risk factors, or the impact of these risk factors may differ by ethnicity or sex. Over the 16 years (1971-1987) of the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study, 880 incident cases of diabetes mellitus developed among 11,097 white and black participants who were between the ages of 25 and 70 years at baseline. There were substantial differences among the four race/sex groups with respect to age at baseline, as well as marked differences in the distribution of several major risk factors for diabetes, including obesity, subscapular and triceps skinfold thickness, blood pressure, income, activity, and educational level. The age-adjusted incidence of diabetes over the course of the study was 15.0% among black women, while it was 10.9% among black men. White women and men experienced similar, more moderate risks of 7.0% and 6.9%, respectively. The 100% excess risk among black women and the 50% excess among black men can in large measure explain the recent marked increase in diabetes rates in the black community. Furthermore, at nearly every level of obesity, blacks had a higher risk of diabetes than whites, suggesting that other factors contributed to risk. A significant interaction between race and body mass index (weight (kg)/height(m)2) was likewise demonstrated in multivariate analysis. Baseline age, race, body mass index, and ratio of subscapular skinfold to triceps skinfold were significantly related to incident diabetes, both overall and in separate models for men and women; in the entire cohort and in women alone, blood pressure, activity level, and education also contributed to risk. Other interactions were tested but were not found to be important. Despite sampling difficulties and inconsistencies in the data, the NHANES I Epidemiologic Follow-up Study provides evidence that the associations of anthropometric and sociodemographic variables with diabetes may vary among subgroups which have different mean levels and distributions of these risk factors.

Adult↗
PubMed1993

Oxygen-radical absorbance capacity assay for antioxidants.

A relatively simple but sensitive and reliable method of quantitating the oxygen-radical absorbing capacity (ORAC) of antioxidants in serum using a few microliter is described. In this assay system, beta-phycoerythrin (beta-PE) is used as an indicator protein, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a peroxyl radical generator, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, a water-soluble vitamin E analogue) as a control standard. Results are expressed as ORAC units, where 1 ORAC unit equals the net protection produced by 1 microM Trolox. The uniqueness of this assay is that total antioxidant capacity of a sample is estimated by taking the oxidation reaction to completion. At this point all of the nonprotein antioxidants (which include alpha-tocopherol, vitamin C, beta-carotene, uric acid, and bilirubin) and most of the albumin in the sample are oxidized by the peroxyl radical. Results are quantified by measuring the protection produced by antioxidants. This solves many problems associated with kinetics or lag-time measurements. A linear correlation of ORAC value with concentration of serum. Trolox, vitamin C, uric acid, and bovine albumin is demonstrated. The coefficient of variation within a run is found to be about 2% and from run to run about 5%. Trolox, alpha-tocopherol, vitamin C, beta-carotene, uric acid, and bilirubin completely protect beta-PE from oxidation, while bovine albumin protects beta-PE only partially. On a molar basis, the relative peroxyl radical absorbance capacity of Trolox, alpha-tocopherol acid succinate, uric acid, bilirubin, and vitamin C is 1:1:0.92:0.84:0.52. Bovine albumin per unit weight has a lower peroxyl absorbing capacity than these antioxidants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Sex differences in the impact of coexistent diabetes on survival in patients with coronary heart disease.

OBJECTIVE: To evaluate the sex difference in the impact of diabetes on survival in patients with coronary heart disease. RESEARCH DESIGN AND METHODS: Cohort study based on a sample from a hospital registry in Chicago, IL. A total of 974 consecutive patients (585 men and 389 women) with angiographically confirmed coronary artery disease were followed for 4.6 yr. RESULTS: At baseline, 160 men and 155 women had diabetes. The age-adjusted relative risk of death from all causes for patients with diabetes versus patients without diabetes was 0.93 (95% confidence interval 0.65-1.34) in men and 1.99 (95% CI 1.30-3.05) in women. For cardiac death, the corresponding relative risk was 1.00 (95% CI 0.64-1.56) and 1.96 (95% CI 1.19-3.24) in men and women, respectively. Baseline differences in age, hypertension, body mass index, number of diseased vessels, and ejection fraction did not fully explain the excess mortality risk in diabetic women. Excess risk was apparent in both cardiac and noncardiovascular categories. Among nondiabetic patients, the risk of death was significantly lower in women compared with men (multivariate-adjusted relative risk = 0.61, 95% CI 0.41-0.89). However, the mortality risk of diabetic women became similar to men as a whole (relative risk = 1.13, 95% CI 0.80-1.60). CONCLUSIONS: Diabetes confers a substantially higher risk of mortality in women than in men when it occurs in the presence of coronary heart disease.

Age Factors↗
PubMed1992

The prognostic role of left ventricular hypertrophy in patients with or without coronary artery disease.

OBJECTIVE: To examine the association between echocardiographically determined left ventricular hypertrophy and mortality in patients with and without coronary artery disease. DESIGN: Cohort study with a mean follow-up period of 4 years. SETTING: An inner-city public hospital in Chicago. PATIENTS: A cohort of 785 patients, most of whom were black and had hypertension. INTERVENTIONS: Coronary arteriography for presumed coronary artery disease and echocardiography. MAIN OUTCOME MEASURE: All-cause and cardiac mortality. RESULTS: Left ventricular hypertrophy, based on left ventricular mass corrected for body surface area, was present in 194 of 381 patients (51%) with coronary artery disease and in 162 of 404 patients (40%) without coronary artery disease. Patients with left ventricular hypertrophy had worse survival than those without hypertrophy in both the group with coronary artery disease and the group without coronary artery disease. After adjustment was made for age at baseline, sex, and hypertension, the relative risk for death from any cause in patients with hypertrophy compared with patients without hypertrophy was 2.14 (95% CI, 1.24 to 3.68) among those with coronary artery disease and 4.14 (CI, 1.77 to 9.71) among those without coronary artery disease. CONCLUSIONS: Echocardiographically determined left ventricular hypertrophy is an important prognostic marker in patients with or without coronary artery disease. The effect of reversing ventricular hypertrophy in patients with and without coronary disease deserves further study.

Adult↗
PubMed1992

Changes in pulmonary hemodynamics with aging in a predominantly hypertensive population.

The impact of aging on pulmonary hemodynamics was investigated in 322 patients who underwent right- and left-sided cardiac catheterization and echocardiographic examination, and were free of coronary disease, impaired left ventricular systolic function and left ventricular dilatation. Most of the patients were black (83%) and hypertensive (78%). Mean pulmonary artery pressures increased progressively with age: 16.7 +/- 4.6, 17.9 +/- 6.4 and 20.6 +/- 8.0 mm Hg for those aged less than 45 (n = 50), 45 to 64 (n = 238) and greater than or equal to 65 years (n = 34), respectively (p = 0.020). Pulmonary vascular resistance was 99 +/- 42, 116 +/- 62 and 160 +/- 68 dynes s cm-5, and the ratio of pulmonary to systemic vascular resistance was 78, 80 and 105%, respectively, for the 3 age groups (p less than 0.001). Along with these changes, a decrease in cardiac output and an increase in systolic blood pressure and systemic vascular resistance with age were noted. The effect of age on mean pulmonary artery pressure and pulmonary vascular resistance was statistically significant after adjustment for gender, smoking status, body weight, left ventricular hypertrophy, systolic blood pressure and systemic vascular resistance. Consideration should be given to age-related changes in the pulmonary circulation when defining physiologically normal values.

Aged↗
PubMed1991

[Effects of zinc deficiency and supplements on lipid peroxidation and superoxide dismutase in mice].

56 weanling Balb/c mice were assigned to Zn deficiency (ZD, n = 40), pair-fed (PF, n = 8) and fed ad libitum (AL, n = 8) groups according to their sex and weight, ZD mice were fed Zn-deficient (Zn: 1.6 ppm) diet, and PF and AL mice were fed control (Zn: 51.6 ppm) diet. After 6 weeks, 8 mice were taken out from ZD group and killed with all PF and AL mice. Blood and liver were sampled for the assays of Zn, Cu, malondialdehyde (MDA) and superoxide dismutase (SOD). The other 32 ZD mice were divided into four groups and supplemented with 0, 5, 50 and 500 ppm Zn in the Zn-deficient diet respectively. After another 3 weeks they were also killed and used for the measurements of Zn, Cu, MDA and SOD. The results showed that Zn deficiency increased MDA formation and decreased SOD activity in the liver of mice. Supplementation of 5 or 50 ppm Zn for 3 weeks enabled a satisfactory recovery of all the indices in ZD mice. But 500 ppm Zn increased MDA formation and decreased SOD activity further. This could be explained by the secondary Cu deficiency in mice.

Animals↗
PubMed1991

[The influence of vagotomy on stomach endocrine cells in rat].

UNLABELLED: The effects of unilateral truncal vagotomy (UTV) and bilateral truncal vagotomy (BTV) on antrum EC cells, G cells and oxyntic gland area argyrophil cells were studied in rats by using immunohistochemistry processes, Grimelius argyrophil stain and microscopic image analysis technique. RESULTS: (1) In UTV animals, two weeks postoperation, the sectional areas of EC cells were significantly smaller in denervated side than In the other side (17%, P less than 0.05). In the innervated side of antrum, the sectional areas of EC cells were larger than those in controls (13.5%, P less than 0.05). But, five weeks after UTV, the size of EC cells was not significantly different in all animals. These suggest that vagal denervation can inhibit relatively the functional activity in a short period, but this inhibition could be compensated later. (2) There were no morphological changes in G cells of UTV rats. In BTV animals, the quantity of G cells in antrum increased by 36.2% (P less than 0.05) and their sectional areas were larger than those in sham by 26.2% (P less than 0.05). These indicate that the function of G cells is more active in BTV animals and the functional change of G cells is related to the pH value of gastric juice. (3) In UTV rats, the oxyntic gland area argyrophil cells (ECL cells are dominant) were significantly reduced in two weeks (26.8%, P less than 0.01) and in five weeks (20.1%, P less than 0.05) in denervated side after UTV. The cells became smaller also. These suggest that vagus can influence the function, proliferation and growth of ECL cells.

Animals↗