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Biomedical subjects

Z Huang

Publications and source records attributed to Z Huang.

At least 451 records · Page 25Linked to original sources
PubMed1994

High density cultivation of a recombinant CD-1 cell line producing prourokinase using a Biosilon microcarrier culture system.

CD-1, a genetically-engineered CHO cell line, was cultivated with a Biosilon microcarrier culture system. We successfully cultivated CD-1 cells to a very high density (over 1 x 10(7) cells/ml). Prourokinase was stably secreted at about 180 IU/10(6) cells/24 h. Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers, then reattach and proliferate on fresh microcarriers. This makes it very easy to scale up production. The microcarriers could be reused several times without affecting adhesion, proliferation and prourokinase secretion. With CM-PECC membrane radial flow chromatography and MPG chromatography, the prourokinase in conditioned medium could be purified to a specific activity of 1 x 10(5) IU/mg of protein. The purification factor was about 600 fold, and approximately 90% of the biological activity was recovered.

Animals↗
PubMed1994

[The effects of brain ischemia and electroacupuncture on cortical somatosensory evoked potential in rats].

The dynamic changes of cortical somatosensory evoked potential during occluding bilateral common carotid arteries and electroacupuncturing "Hegu" point were recorded and observed IN 30 wistar rats anesthetized with chloralose and urethane, The main results were as follows: After brain ischemia, P. N. amplitudes of SEP were significantly depressed, and the spike latency of SEP is obviously increased. The decreased amplitude of SEP during brain ischemia could be obviously increased by electroacupuncturing "Hegu" point. It is suggested that SEP may be an indicator to show brain ischemia and acupuncturing "Hegu" point could improve brain ischemia.

Animals↗
PubMed1994

The sequence of xylose isomerase gene from Streptomyces diastaticus No. 7 M1033.

The DNA sequence of the xylose isomerase gene from Streptomyces diastaticus No. 7 M1033 from Hainan Province has been determined. The structure gene of the enzyme is composed of 1161bp, corresponding to 387 amino acid residues. The G+C content of the gene is 72.1%. The probability of G or C on the third position of the codon is 98%. At the level of amino acids, this xylose isomerase displays high homology with those from other Actinomycete strains, particularly those from Streptomyces strains.

Aldose-Ketose Isomerases↗
PubMed1994

[The use of finite population sampling and lot quality assurance sampling in estimating "immunization coverage rate" in villages (towns)].

We have used Finite Population Sampling and Lot Quality Assurance Sampling (LQAS) in a field survey of "immunization coverage rate" for EPI in three villages (towns) in Lanxi Zhejiang Province. The results showed that there was no significant difference (P > 0.05) between the rates of two samplings and between the rate of sampling and population. These results indicated that both Finite population Sampling and LQAS are cheap and simple, and can represent the immunization coverage level of population.

Female↗
PubMed1994

A north-south comparison of blood pressure and factors related to blood pressure in the People's Republic of China: a report from the PRC-USA Collaborative Study of Cardiovascular Epidemiology.

OBJECTIVES: To compare blood pressures in northern (Beijing) and southern (Guangzhou) Chinese population samples aged 35-54 years, males and females, urban and rural, and to assess the role of blood pressure-related traits in explaining north-south differences. DESIGN: Cross-sectional surveys were conducted in 1983-1984 of northern and southern populations employed in industry (urban) or farming (rural). METHODS: In the north samples were selected from the Capital Iron and Steel Complex (urban) and Shijingshan district (rural); in the south samples from the Guangzhou Shipyard (urban) and Panyu County (rural) were used. RESULTS: The number of subjects surveyed in north and south were 4706 and 4179, respectively: 1500 and 1052 urban males, and 717 and 914 rural males; and 1300 and 1061 urban females, and 1189 and 1152 rural females, respectively. Average systolic (SBP) and diastolic (DBP) blood pressures, were consistently higher in the north than in the south. SBP and DBP were significantly and independently related to age, body mass index, heart rate, use of antihypertensive drugs, serum triglycerides level, alcohol use (males only) and inversely to cigarette smoking. Northerners were older, taller, heavier and had higher body mass index and triglycerides level than southerners. With adjustment of SBP and DBP for blood pressure-related traits, north-south blood pressure differences decreased, but remained significant for urban males, rural males and rural females, with sizeable differences for rural samples in particular. CONCLUSIONS: North-south differences in blood pressure in these samples are accounted for only partly by north-south differences in the cited blood pressure-related traits. The role of other traits requires assessment.

Adult↗
PubMed1994

[A cohort study on the relationship between the mortality of cerebro-vascular diseases and farmer smokers].

The relationship between the mortality of cerebro-vascular diseases and farmer smokers in Shifang County was studied. The results indicated that the mortality of cerebro-vascular diseases in the male groups of cigarette-smokers older than 65 and cigar-smokers older than 55 was significantly higher than that of the nonsmokers (P < 0.05), the RR being 1.68-3.22. Also, the mortality in the female groups of cigarette-smokers older than 55 and cigar-smokers older than 65 was significantly higher than that of the non-smokers (P < 0.05), the RR being 1.99-3.19. The sex-specific mortalities of the other age groups revealed no significant differences in spite of some inequalities in smoking (P < 0.05). Age should be one of the risk factors for the death of cerebro-vascular diseases regardless of the sex. The mortality rose with the increasing accumulated amount of smoking. The relationship was not significant between the mortality of cerebro-vascular diseases and short-term smokers with small dose (P > 0.05). However, when the accumulated amount reached certain degree, i.e. the smoker consumed cigar more than 270 kg or consumed cigarette more than 10,000 packs, the relationship between the behavior of cigar-smoking and cigarette-smoking and the mortality became apparent, the RR being 2.53-3.91 (P < 0.01).

Adult↗
PubMed1994

[The efficacy and side reactions in humans immunized with Danish strain of dried BCG of Shanghai].

A procedure of keeping Danish BCG strain 2 is reported. The strain is cultivated in Bile potato Medium and Suton Potato Medium alternatively with incubation periods of two weeks. Lyophilized vaccine produced by using seeds derived from this strain gives better immunogenicity and lower side reaction to new-born babies and has better thermostability in compare with vaccines derived from strains of Beijing, Brazil, CCCP, France of Hungary.

Animals↗
PubMed1994

High density cultivation of genetically-engineered CHO cell lines with microcarrier culture systems.

Genetically-engineered CHO cell lines, r beta-13 and CLF-8B2, were cultivated with the MC-1 microcarrier culture system. The cell density could be enhanced by increasing the concentration of microcarrier. At a microcarrier concentration of 10 mg/ml, the cell density could reach 4 to 5 x 10(6) cells/ml. It was shown that these cell lines would spontaneously release from the microcarrier to attach to and proliferate on fresh microcarriers. We were thus able to scale up cultivation using a simple method, i.e. by adding fresh microcarriers and medium directly into the culture system to about 2, 4 or 8 times the original volume. Using a perfusion culture system, we have successfully cultivated CLF-8B2 cells in a 2 L bioreactor for several weeks at medium perfusion rates of 0.5 to 3 working volumes. Prourokinase was stably secreted.

Animals↗
PubMed1994

[The study of insertion sequence on IS2. I. Polarity and inserted direction of IS2].

By using flj B, flj A selecting system, we investigated the effects of the insertion of IS2 into certain genes and found that IS2 could be inserted into the gene from either the left side or the right side resulting in the loss of its activity and inhibition of the next gene's expression within the same transcription. The polarities were different when IS2 was inserted from the left side or the right side. The results from the artificial testing system were the same as those obtained from the natural state.

Bacterial Proteins↗
PubMed1993

Conversion of alpha-helices into beta-sheets features in the formation of the scrapie prion proteins.

Prions are composed largely, if not entirely, of prion protein (PrPSc in the case of scrapie). Although the formation of PrPSc from the cellular prion protein (PrPC) is a post-translational process, no candidate chemical modification was identified, suggesting that a conformational change features in PrPSc synthesis. To assess this possibility, we purified both PrPC and PrPSc by using nondenaturing procedures and determined the secondary structure of each. Fourier-transform infrared (FTIR) spectroscopy demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), findings that were confirmed by circular dichroism measurements. In contrast, the beta-sheet content of PrPSc was 43% and the alpha-helix 30% as measured by FTIR. As determined in earlier studies, N-terminally truncated PrPSc derived by limited proteolysis, designated PrP 27-30, has an even higher beta-sheet content (54%) and a lower alpha-helix content (21%). Neither PrPC nor PrPSc formed aggregates detectable by electron microscopy, while PrP 27-30 polymerized into rod-shaped amyloids. While the foregoing findings argue that the conversion of alpha-helices into beta-sheets underlies the formation of PrPSc, we cannot eliminate the possibility that an undetected chemical modification of a small fraction of PrPSc initiates this process. Since PrPSc seems to be the only component of the "infectious" prion particle, it is likely that this conformational transition is a fundamental event in the propagation of prions.

Animals↗
PubMed1993

Development of choline and acetylcholine Pt microelectrodes.

Choline (Ch) and acetylcholine (Ach) microenzyme sensors were developed based on the immobilization of choline oxidase (ChO) and acetylcholinesterase (AchE) at the tip of a 25-micron Pt wire sealed in glass. Several immobilization procedures were tested, including code-position of the enzyme/s with an electropolymer and cross-linking with glutaraldehyde. The various electropolymers used were 1,2-diaminobenzene, resorcinol, 4-hydroxybenzenesulfonic acid, and a combination of two polymers, 1,2-diaminobenzene and resorcinol. An inner membrane constructed from cellulose acetate (CA) was deposited prior to immobilization with glutaraldehyde. The analytical characteristics of the microelectrodes, including optimization of immobilization procedures, calibration curves, pH response curves, stability, and selectivity toward possible electroactive compounds found in the brain extracellular fluid, were determined. The best microelectrodes were prepared by cross-linking the enzymes with glutaraldehyde on top of the inner CA membrane. The responses are linear in the concentration range 5.0 x 10(-7)-1.0 x 10(-4) M Ch and 5.0 x 10(-7)-9.3 x 10(-5) M Ach. The time to reach 95% steady-state current was 15-20 s. The CA-coated Ch microelectrodes were useful for measurement of changes in Ch concentration in artificial brain extracellular fluid.

Acetylcholine↗
PubMed1993

Mechanisms of ferulic acid conversions to vanillic acid and guaiacol by Rhodotorula rubra.

Resting cells of Rhodotorula rubra converted transferulic acid (1) to vanillic acid (2), then to guaiacol (3) and protocatechuic acid (4), under aerobic conditions. In an argon atmosphere, R. rubra transformed ferulic acid to vanillic acid and 4-hydroxy-3-methoxystyrene (5). Metabolites were isolated by solid-phase extraction and characterized by mass spectrometry, 1H, and 13C-nuclear magnetic resonance spectroscopy (NMR). The biotransformation of ferulic acid to vanillic acid by R. rubra cell-free extracts required CoA, ATP, and NAD+. Mass spectrometry and 13C-NMR were used to demonstrate the incorporation of oxygen from H2(18)O during the conversion of ferulic acid to vanillic acid. The results suggest a parallel between this bioconversion reaction and the beta-oxidation of fatty acids. Proton-carbon correlation NMR spectroscopy was used to demonstrate the specific incorporation of deuterium from D2O into guaiacol obtained from vanillic acid. The incorporation of deuterium implicates the involvement of a quinoid vanillic acid tautomer as an intermediate in the decarboxylation reaction.

Cell-Free System↗
PubMed1993

Slow- and tight-binding inhibitors of the 85-kDa human phospholipase A2.

A trifluoromethyl ketone analogue of arachidonic acid in which the COOH group is replaced with COCF3 (AACOCF3) was prepared and found to be a tight- and slow-binding inhibitor of the 85-kDa cytosolic human phospholipase A2 (cPLA2). Enzyme inhibition was observed when AACOCF3 was tested in assays using either phospholipid vesicles or phospholipid/Triton X-100 mixed micelles. The fact that the inhibition developed over several minutes in both assays establishes that AACOCF3 inhibits by direct binding to the enzyme rather than by decreasing the fraction of enzyme bound to the substrate interface. From the measured values of the inhibitor association and dissociation rate constants, an upper limit of the equilibrium dissociation constant for the Ca(2+).AACOCF3.PLA2 complex of 5 x 10(-5) mole fraction was obtained. Thus, detectable inhibition of cPLA2 by AACOCF3 occurs when this compound is present in the assay at a level of one inhibitor per several thousand substrates. Arachidonic acid analogues in which the COOH group is replaced by COCH3, CH(OH)CF3, CHO, or CONH2 did not detectably inhibit the cPLA2. The arachidonyl ketones AACOCF2CF3 and AACOCF2Cl were found by 19F NMR to be less hydrated than AACOCF3 in phospholipid/Triton X-100 mixed micelles, and compared to AACOCF3 these compounds are also weaker inhibitors of cPLA2. In keeping with the fact that cPLA2 displays substrate specificity for arachidonyl-containing phospholipids, the arachidic acid analogue C19H39COCF3 is a considerably less potent inhibitor compared to AACOCF3.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acids↗