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Biomedical subjects

S Dai

Publications and source records attributed to S Dai.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Saccharification of corn stover by immobilized Trichoderma reesei cells].

The mycelia of Trichoderma reesei Rut C30 were adsorbed and immobilized within the porous polyurethane supporter. It was found that the synthesis of cellulase by the immobilized cells and the enzymatic hydrolysis of corn stover were able to be carried out in a nitrogen source-limiting medium. Under repeated batch processes with 60 g/L corn stover pretreated by 2% NaOH at 85 degrees C, the average cellulase activity (FPA) was 0.70 IU/ml, the concentration and yield of the reducing sugar were 26.41 g/L and 89.11% respectively after shaking culture at 150 r/min, 30 degrees C, pH 4.8 for 108 h. Total of 12 repeated batches were performed in 54 days. The immobilized cells kept the weight around 10 g/L. The fed-batch process was also studied with the same immobilized cells. Total of 120 g/L corn stover was added in different feeding manners. The reducing sugar of 52.8 g/L was produced after 7 days and the saccharification efficiency (89.2%) was almost the same as the batch process. The results indicated that the cellulase production and cellulosic material saccharification in situs by the immobilized Trichoderma reesei cells is an convenient and effective process for conversion and utilization of renewable biomass.

Cells, Immobilized↗
PubMed1997

RF2a, a bZIP transcriptional activator of the phloem-specific rice tungro bacilliform virus promoter, functions in vascular development.

Rice tungro bacilliform virus (RTBV) replicates only in phloem cells in infected rice plants and its promoter drives strong phloem-specific reporter gene expression in transgenic rice plants. We isolated a cDNA encoding a basic leucine zipper (bZIP) protein, RF2a, which binds to the Box II cis element that is important for expression from the promoter. RF2a, which stimulates Box II-dependent transcription in a homologous in vitro transcription system, accumulates in nuclei of phloem and certain other cell types in shoots, but is found at only very low levels in roots. Transgenic antisense plants in which RF2a accumulation was suppressed had normal roots but stunted, twisted leaves with small, disorganized vascular bundles, an enlarged sclerenchyma and large air spaces. We propose that the RTBV promoter exploits a host transcription factor that is critical for leaf tissue differentiation and vascular development for its expression.

Amino Acid Sequence↗
PubMed1997

Development of cardiovascular risk factors from ages 8 to 18 in Project HeartBeat! Study design and patterns of change in plasma total cholesterol concentration.

BACKGROUND: Project HeartBeat! is a longitudinal study of the development of cardiovascular risk factors as growth processes. Patterns of serial change, or trajectories, from ages 8 to 18 years for plasma total cholesterol concentration (TC) and percent body fat illustrate the design and synthetic cohort approach of the study. METHODS AND RESULTS: Six hundred seventy-eight children (49.1% female, 20.1% black) entered the study at ages 8, 11, and 14 years and were followed up with examinations every 4 months for < or = 4 years. Multilevel analysis demonstrated trajectories for population mean values of TC and percent body fat in sex-specific synthetic cohorts from ages 8 to 18 years. Polyphasic patterns of change in TC were confirmed, with notable sex differences in age patterns and with minimum mean values of TC of 3.85 mmol/L for females and 3.59 for males. As illustrated by data for males, the approximate 75th percentile values of mean TC ranged from 4.78 mmol/L at its early peak to 4.06 at its late-teen nadir. Percent body fat exhibited a trajectory closely parallel with that for TC only for males and appeared to be unrelated for females. CONCLUSIONS: The polyphasic trajectory for TC from ages 8 to 18 years differs between females and males, indicates marked age variation in 75th percentile values and, in males only, closely parallels the trajectory for percent body fat. These and other results indicate the value of both follow-up every 4 months across age intervals to detect rapid risk factor change and the synthetic cohort approach for gaining new insights into the dynamics and possible determinants of this change from ages 8 to 18 years.

Adipose Tissue↗
PubMed1997

Identification and functional characterization of a calcium channel gamma subunit.

A positive selection technique was used to identify novel auxiliary calcium channel subunits that are similar to the skeletal muscle gamma subunit. A new rat gamma subunit cDNA was found, which was highly expressed in skeletal muscle tissue and was detected by RT-PCR in cardiac tissue. The 223-amino-acid-protein shares 84% and 79% identity, respectively, with the human and rabbit skeletal muscle subunits. Northern blot analysis revealed a single transcript of 1.5 kb in rat skeletal muscle, but not in cardiac tissue. Transient coexpression with the cardiac calcium channel complex demonstrated that the gamma subunit shifted the inactivation curve to negative potentials and accelerated current inactivation without changing other voltage-dependent properties of the channel.

Amino Acid Sequence↗
PubMed1997

Inhibition of plasma membrane NADH oxidase activity and growth of HeLa cells by natural and synthetic retinoids.

Several retinoids, both natural and synthetic, were evaluated for their ability to modulate NADH oxidase activity of plasma membranes of cultured HeLa cells and the growth of HeLa cells in culture. Both NADH oxidase activity and the growth of cells were inhibited by the naturally-occurring retinoids all trans-retinoic acid (tretinoin) and retinol as well as by the synthetic retinoids, trans-acitretin, 13-cis-acitretin, etretinate and arotonoid ethylester (Ro 13-6298). For all retinoids tested, inhibition of NADH oxidase activity and inhibition of growth were correlated closely. With tretinoin, etretinate and arotonoid ethylester, NADH oxidase activity and cell growth were inhibited in parallel in proportion to the logarithm of retinoid concentration over the range of concentrations 10(-8) to 10(-5) M. Approximately 70% inhibition of both NADH oxidase activity and growth was reached at 10 microM. With retinol, trans-acitretin and 13-cis-acitretin, inhibition of NADH oxidase activity and growth also were correlated but maximum inhibition of both was about 40% at 10 microM. The possibility is suggested that inhibition of the plasma membrane NADH oxidase activity by retinoids may be related to their mechanism of inhibition of growth of HeLa cells in culture.

Animals↗
PubMed1997

[The expression of P16, Rb and cyclin D1 and biological behavior of laryngeal cancer].

To determine the effect of gene of carcinorma on the proliferation and regulation in primary laryngeal cancer, P16, Rb, Cyclin D1 were examined with immunohistochemical SABC method in 36 cases of primary laryngeal cancer. The results showed: P16 was positive in 11 of 36 in carcinoma specimens (30.6%), 22 of 36 in the specimens surrounding the carcinoma (61.1%) were positive. The difference was significant (P < 0.05). The positive rates of Rb and Cyclin D1 were 61.1% and 47.2% respectively. Comparing the positive rate of P16 to Rb was more significantly (P < 0.05). In most circumstances, when Rb was positive, P16 was negative and vice versa. The positive rate of Rb correlated with the one of Cyclin D1 positively by rank correlation. The expression of P16 and Rb was significantly different between well and poor tissues differenciation. The expression had no significant difference in the same antibody in various clinical stage and position or in the same stage and position but different antibody. The results suggest that the feedback regulation chain consisted of P16 plays an important role in the proliferation and regulation.

Aged↗
PubMed1997

Experimental study on biodynamic response to vibration in human and animals.

In order to study the characteristics of human dynamic response to vibration, 56 subjects were exposed to vibration on X, Y and Z axes. It showed that there were two resonance peaks of most local parts of the human body. The curves of transmissibility are essentially the same in all the subjects. It was found that resonance frequencies of the human body decreased with increase of G levels of vibration. These characteristics were also proved in animals. Using three-level artificial neural network, common reflective relation of the resonance frequency with height and weight of the human body and exciting acceleration were obtained. The above findings might be applicable to studies of vibration ergonomics.

Acceleration↗
PubMed1997

[Development of a SIRI-TOFMS and the application research progress].

The only one set of Sputter Initiated Resonance Ionization-Time of Flight Mass Spectrometer (SIRI-TOFMS) in China was designed and developed. A liquid gallium ion source with micron level diameter of beam, frame-style piezoeletric ceramic sub-micron sample manipulator, a secondary electron imaging system and a computer controlled precise targeting system as well as a real colour big screen image displaying system were added so as to improve its microanalysis capability. By means of this apparatus, trace analysis of Au in minerals and Cu in standard steel samples were carried out. The detection limit of them is 40ng/ and microg/g level, respectively. Aside from the above detections, other preliminary researches ere also performed.

English Abstract↗
PubMed1997

Finding health and AIDS information in the mass media: an exploratory study among Chinese college students.

Western health officials believe the incidence of HIV infection in the People's Republic of China is much higher than has been reported, but knowledge about the disease remains low. This paper describes a preliminary study of Chinese college students' AIDS knowledge and beliefs and of the acceptability of mass media for AIDS education. Focus group interviews of 73 Xiamen University students showed that the students used radio more consistently than any other media and viewed magazines as the best media source of health information. However, they expressed a general distrust of the health information media offer. They possessed quite a bit of accurate information about AIDS but also harbored many inaccurate beliefs. Most felt that their personal risk from AIDS was very low because they felt distanced--either geographically or morally--from those at risk. Disturbing numbers felt that fate, not individual behavior, determines whether or not a person contracts HIV. The paper discusses the study's implications for future research.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Crystal structure of Arabidopsis thaliana NADPH dependent thioredoxin reductase at 2.5 A resolution.

Thioredoxin exists in all organisms and is responsible for the hydrogen transfer to important enzymes for ribonucleotide reduction and the reduction of methionine sulphoxide and sulphate. Thioredoxins have also been shown to regulate enzyme activity in plants and are also involved in the regulation of transcription factors and several other regulatory activities. Thioredoxin is reduced by the flavoenzyme thioredoxin reductase using NADPH. We have now determined the first structure of a eukaryotic thioredoxin reductase, from the plant Arabidopsis thaliana, at 2.5 A resolution. The dimeric A. thaliana thioredoxin reductase is structurally similar to that of the Escherichia coli enzyme, and most differences occur in the loops. Because the plant and E. coli enzymes have the same architecture, with the same dimeric structure and the same position of the redox active disulphide bond, a similar mechanism that involves very large domain rotations is likely for the two enzymes. The subunit is divided into two domains, one that binds FAD and one that binds NADPH. The relative positions of the domains in A. thaliana thioredoxin reductase differ from those of the E. coli reductase. When the FAD domains are superimposed, the NADPH domain of A. thaliana thioredoxin reductase must be rotated by 8 degrees to superimpose on the corresponding domain of the E. coli enzyme. The domain rotation we now observe is much smaller than necessary for the thioredoxin reduction cycle.

Amino Acid Sequence↗
PubMed1996

AIDS knowledge, attitudes and beliefs among Chinese college students: implications for PSA development.

With growing numbers of reported HIV cases in The People's Republic of China, PRC health officials face the same information dissemination problems that have plagued other nations for a decade. The purpose of this study was to begin to understand Chinese college students' knowledge, attitudes and beliefs about HIV/AIDS as well as the cultural barriers which may prevent the acceptance of AIDS public service efforts. Focus group interviews were conducted with 76 college students at Xiamen University, PRC. Interviews revealed that many inaccurate beliefs exist regarding the AIDS disease and its modes of transmission. While many of the respondents reported that fate was the determining factor in trans mission of HIV, most felt distanced--physically, morally and culturally--from those at risk.

Acquired Immunodeficiency Syndrome↗
PubMed1996

[Lectin-binding histochemical study on developing corneal epithelium and stroma of normal human being].

PURPOSE: To study glycoconjugates in developing cornea of normal human. METHODS: Lectin-binding histochemical method with five biotin-coupled lectins (conA, LCA, PNA, WGA, RCA). RESULTS: 1. WGA mainly stained the membrane of epithelial cells, especially in surface cells. It also stained anterior stroma of embryo. 2. All the layers of epithelium could be stained by conA, uneven stain was seen in stroma of embryo corneas. 3. RCA, LCA receptor distributed in base of cornea epithelium. 4. PNA can only stain cornea epithelium of 16 embryo. CONCLUSIONS: 1. Glycoconjugates of binding conA, WGA, PNA, LCA, RCA are in the developing corneas of human. 2. The distribution of these lectin receptors may change with corneal developing. It may be related to the maturity of corneas.

Corneal Stroma↗
PubMed1996

Cardiac cytotoxic mechanism mediated by antibodies against myocardial mitochondrial ADP/ATP carrier in patients with dilated cardiomyopathy.

OBJECTIVE: To investigate mechanism of the antibody-mediated cardiac cytotoxicity and clinical significance in dilated cardiomyopathy (DCM), and study the effects of the antibodies against the myocardial mitochondrial ADP / ATP carrier from sera of patients with dilated cardiomyopathy on the guinea pig ventricular myocytes. PATIENTS AND METHODS: This study included 18 patients with DCM (12 men and 6 women), with mean age of 43 years. Control group included 18 health donors, (9 men and 9 women), with mean age of 32 years. The antibodies against the ADP / ATP carrier and cell membrane 52 000 peptide were examined by immunoblotting. The antibody-mediated cardiac cytotoxicity was studied with the cytotoxic test and whole cell patch-clamp technique. RESULTS: The antibodies against myocardial mitochondrial ADP / ATP carrier and cell membrane 52 000 peptide were positive in 18 patients with DCM, while negative in controls. The antibodies induced cytotoxic damage with time-dependent and enhanced Ca-current in cardiac myocytes. The increasing amplitude of peak Ca(2+)-current was 100 pA-840 pA (n = 8) in different dilution of the antibodies. The effect of the antibodies might be inhibited by verapamil, and were null in controls (n = 4). CONCLUSIONS: The above findings suggest that an increase in the antibody-mediated Ca(2+)-current of cardiac myocytes is related to the cytotoxic damage in dilated cardiomyopathy.

Adult↗
PubMed1996

Effects of low and high dose administration of bis(maltolato)oxovanadium(IV) on fa/fa Zucker rats.

The fatty Zucker rat, characterized by obesity, hyperinsulinemia, hyperlipidemia, and mild hyperglycemia, has been suggested as an animal model of non-insulin-dependent diabetes mellitus. The present study examined the chronic dose-dependent effect of bis(maltolato)oxovanadium(IV), a potent insulin mimetic, in this animal model of diabetes. Chronic (6 weeks) oral administration of bis(maltolato)oxovanadium(IV) (0.06 mmol.kg-1.day-1, low dose study) was effective in reducing the hyperinsulinemia associated with the fatty Zucker rat model (termination insulin: lean, 82.8 +/- 21.6; fatty, 732 +/- 89.4; fatty treated, 336 +/- 126.6 pmol/L; p < 0.05). Pancreatic perfusion data indicated a significant improvement in insulin secretory function in the fatty rats. The dose dependency of this relationship was observed in the high dose study (0.128 mmol.kg-1.day-1 for 14 weeks), wherein bis(maltolato)oxovanadium(IV) treatment restored plasma insulin levels in the fatty rats to lean levels (termination insulin: lean, 199.2 +/- 17.4; fatty 660.6 +/- 12.6; fatty treated, 153.6 +/- 9.6 pmol/L; p < 0.05) and significantly improved insulin response to a glucose challenge. In addition, bis(maltolato)oxovanadium(IV) treatment (high dose study) ameliorated the age-dependent increase in blood pressure observed in fatty Zucker rats (systolic blood pressure: lean, 127 +/- 10; fatty, 176 +/- 5; fatty treated, 156 +/- 9 mmHg (1 mmHg = 133.3 Pa)). These data indicate that chronic oral administration of bis(maltolato)oxovanadium(IV) in the drinking water was effective in reducing hyperinsulinemia, insulin resistance, glucose intolerance, and hypertension in the fatty Zucker rat.

Animals↗
PubMed1996

[Distribution of Bacillus thuringiensis in soils of north and south of China].

221 isolates of Bacillus thuringiensis were isolated in 1491 soil samples from North and South of China. H-serotypes and larvicidal characters of all Bt isolates have been identified. The rate of Bt-harbouring soil sample and the rate of Bt isolates in Northeast and Neimeng were in 12.6% and 17.2% respectively. Predominant serotypes were H4, H10, H3, H13, H5 and H29. The most fertile Bt-harbouring area was the Heilongjiang Province with rate of Bt-harbouring sample of 21.4% and rate of Bt isolate of 29.4%. Rate of Bt-harbouring sample and rate of Bt isolate in Northwest area were 6.6% and 7.1% respectively. Main serotypes were H4, H5, H19, H10 and H3. In four provinces of Southern China, both rates above were 18.6% and 29.5%, but frequency of Bt distribution was varied seriously in different distinct. Predominant serotypes in soils from Southern China were H3 and H5. Results of bioassay showed that the percentage of strains high active to Heliothis armigera and Plogioidera versicolora were 1.6% and 1.1% in soils from North of China. In contrast to North of China, Bt strains active to H. armigera were 5.3% and none of Bt was effective to P. versicolora in South of China. A strain H27-05 was high toxic to H. armigera and showed temperate toxicity to P. versicolora.

Animals↗
PubMed1995

Ascorbic acid supplementation prevents hyperlipidemia and improves myocardial performance in streptozotocin-diabetic rats.

The present study investigated the effects of ascorbic acid (AA) supplementation on the cardiac performance and the plasma levels of glucose, insulin, triglycerides, cholesterol and free fatty acid in diabetic and non-diabetic rats. Diabetes was induced by intravenous injection of streptozotocin (STZ) 55 mg/kg. AA was given in drinking water in concentrations of 1 g/l or 2 g/l for 8 weeks after STZ injection. Myocardial performance was determined using the isolated perfused working heart preparations. Following AA supplementation, there were no significant changes in any of the parameters measured in non-diabetic rats; however, the occurrence of polydipsia, hyperphagia, hyperlipidemia and myocardial dysfunction in STZ-diabetic rats was significantly alleviated in a dose-dependent manner. Nevertheless, the decreased body weight gain, hypoinsulinemia and hyperglycemia in diabetic animals were not affected. The data show that AA supplementation in STZ-diabetic rats improves both hyperlipidemia and cardiac function. However, the mechanisms of these effects and the correlation between these improvements are not clear.

Administration, Oral↗