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Biomedical subjects

S Zhou

Publications and source records attributed to S Zhou.

At least 217 records · Page 12Linked to original sources
PubMed1999

Ability of carnosine and other skeletal muscle components to quench unsaturated aldehydic lipid oxidation products.

Breakdown of lipid peroxides results in the formation of aldehydic compounds which are toxic to biological systems and deleterious to food quality. To determine the potential of skeletal muscle compounds to protect biomolecules from lipid oxidation products, the ability of carnosine and various other related compounds to quench monounsaturated and polyunsaturated aldehydes was investigated. Carnosine, the most abundant dipeptide in skeletal muscle, is capable of quenching alpha,beta-monounsaturated aldehydes and 4-hydroxy-2-trans-nonenal (HNE) more effectively than its constituent amino acid. Carnosine (5 mM) reduced 44% of headspace trans-2-hexenal (0.5 mM) after 1 h incubation at 40 degrees C and pH 7.4. Other histidine-containing dipeptides and the amine compounds, spermine and spermidine, had similar or slightly lower quenching activity than carnosine. Glutathione and thioctic acid had superior quenching ability than carnosine, but their overall contribution to aldehyde quenching compared to carnosine is limited due to their lower concentration in skeletal muscle. The results suggest that carnosine could be important for decreasing the toxicity of lipid oxidation products in biological systems and for minimizing rancidity in muscle foods.

Aldehydes↗
PubMed1999

Ability of amino acids, dipeptides, polyamines, and sulfhydryls to quench hexanal, a saturated aldehydic lipid oxidation product.

Hexanal is a common product arising from the oxidation of omega-6 fatty acids. Because aldehydic lipid oxidation products can react with food components, interactions between hexanal and sulfhydryl- and amine-containing compounds were determined. The polyamines, spermidine and spermine, and the sulfhydryl-containing compounds, glutathione and thioctic acid, decreased headspace hexanal concentrations < or =7.0%. Histidine was the only amino acid tested that was able to quench headspace hexanal. Histidine-containing dipeptides decreased headspace hexanal 3.0-8.5-fold more than histidine. Hexanal quenching by the hisitidine-containing dipeptides increased as the size of the aliphatic side group of the amino acid adjacent to histidine increased, with Leu-His having the greatest hexanal quenching activity. The ability of Leu-His to quench histidine increased with increasing pH. The ability of histidine-containing dipeptides to interact with hexanal suggests that it may be possible to design peptides to alter the concentration of saturated aldehydes in oxidizing lipids.

Aldehydes↗
PubMed1999

Fuzzy segmentation spatiotemporal patterns of cognitive potential into microstates.

Fuzzy c-mean algorithm was applied to segment spatiotemporal patterns of brainwave into microstates and memberships. The optimal clustering number was estimated with both the trends of objective function and the eigenvalue number of microstates. Comparable spatial patterns may occur at different temporal moments in consideration of fuzzy index that is beyond the limit of serial processing. Those techniques were illustrated with multichannel event-related potentials recorded from 9 subjects during Stroop test. Statistical parametric map of F value suggested that significant task (color decision and word decision) effect involve widespread cortical regions after stimulus onset 280 ms and this result supports the hypothesis that Stroop interference derives from response competition during post-perception stage. As significant stimulus (congruent stimulus and incongruent stimulus) effect only involves several separate visual regions within 100 ms after stimulus presentation, it may reflect top-down attentional regulation.

Algorithms↗
PubMed1999

Human fibroblast growth factor receptor 1 is a co-receptor for infection by adeno-associated virus 2.

Adeno-associated virus 2 (AAV)-based vectors have gained attention as a potentially useful alternative to the more commonly used retroviral and adenoviral vectors for human gene therapy. Although AAV uses the ubiquitously expressed cell surface heparan sulfate proteoglycan (HSPG) as a receptor, the transduction efficiency of AAV vectors varies greatly in different cells and tissues in vitro and in vivo. We demonstrate here that cell surface expression of HSPG alone is insufficient for AAV infection, and that AAV also requires human fibroblast growth factor receptor 1 (FGFR1) as a co-receptor for successful viral entry into the host cell. We document that cells that do not express either HSPG or FGFR1 fail to bind AAV and, consequently, are resistant to infection by AAV. These non-permissive cells are successfully transduced by AAV vectors after stable transfections with cDNAs encoding the murine HSPG and the human FGFR1. Furthermore, AAV infection of permissive cells, known to express both FGFR1 and the epidermal growth factor receptor, is abrogated by treatment of cells with basic fibroblast growth factor, but not with epidermal growth factor. The identification of FGFR1 as a co-receptor for AAV should provide new insights not only into its role in the life cycle of AAV, but also in the optimal use of AAV vectors in human gene therapy.

3T3 Cells↗
PubMed1999

Engineering endoglucanase-secreting strains of ethanologenic Klebsiella oxytoca P2.

Recombinant Klebsiella oxytoca P2 was developed as a biocatalyst for the simultaneous saccharification and fermentation (SSF) of cellulose by chromosomally integrating Zymomonas mobilis genes (pdc, adhB) encoding the ethanol pathway. This strain contains the native ability to transport and metabolize cellobiose, eliminating the need to supplement with beta-glucosidase during SSF. To increase the utility of this biocatalyst, we have now chromosomally integrated the celZ gene encoding the primary endoglucanase from Erwinia chrysanthemi. This gene was expressed at high levels by replacing the native promoter with a surrogate promoter derived from Z. mobilis DNA. With the addition of out genes encoding the type II protein secretion system from E. chrysanthemi, over half of the active endoglucanase (EGZ) was secreted into the extracellular environment. The two most active strains, SZ2(pCPP2006) and SZ6(pCPP2006), produced approximately 24 000 IU L-1 of CMCase activity, equivalent to 5% of total cellular protein. Recombinant EGZ partially depolymerized acid-swollen cellulose and allowed the production of small amounts of ethanol by SZ6(pCPP2006) without the addition of fungal cellulase. However, additional endoglucanase activities will be required to complete the depolymerization of cellulose into small soluble products which can be efficiently metabolized to ethanol.

Journal Article↗
PubMed1999

Pilot trial for the assessment of relative bioavailability in generic drug product development: statistical power.

In developing generic drug products, pilot trials are used for identifying successful test formulations to enter pivotal trials. In this study, we derive the power function based on the log-normal distribution and evaluate the effects of potential influential factors-the true test-reference ratio, intrasubject variability, and sample sizes-on the statistical power of a pilot trial to identify successful test formulations, defined as the probability that the test-reference ratio estimate from a pilot trial falls within a predetermined acceptance range when the true ratio is acceptable. Of these influential factors, the test-reference ratio exhibits the largest impact on the statistical power of a pilot trial, followed by intrasubject variability, sample sizes of pivotal trials, and sample sizes of pilot trials. The sample sizes that are used in pilot trials (8-12 subjects) may be sufficient for test products with low intrasubject variability and true ratio close to 1 and may fall short otherwise.

Biological Availability↗
PubMed1999

The effect of peroxisome proliferators on mitochondrial bioenergetics.

Peroxisome proliferators are a group of structurally diverse chemicals that cause the proliferation of peroxisomes in rodents. The purpose of this investigation was to test the hypothesis that the shared effect of these compounds on peroxisome proliferation is mediated through a common inhibitory effect on mitochondrial bioenergetics. Freshly isolated rat liver mitochondria were energized with succinate. The effect of the chemicals on mitochondrial bioenergetics was analyzed by monitoring calcium-induced changes in membrane potential and swelling, as well as changes in mitochondrial respiration. Mitochondrial membrane potential was measured with a TPP(+)-sensitive electrode, and swelling was recorded spectrophotometrically. Mitochondrial oxygen uptake was monitored with a Clark-type oxygen electrode. Gemfibrozil and WY-14,643 induced the mitochondrial permeability transition as characterized by calcium-induced swelling and depolarization of membrane potential, both of which were inhibited by cyclosporine A. Fenofibrate, clofibrate, ciprofibrate and diethylhexyl phthalate, on the other hand, caused a direct dose-dependent depolarization of mitochondrial membrane potential. However, the mechanism of membrane depolarization varied among the test chemicals. Bezafibrate and trichloroethylene elicited no effect on succinate-supported mitochondrial bioenergetics. The results of this investigation demonstrate that although most, but not all, peroxisome proliferators interfere with mitochondrial bioenergetics, the specific biomolecular mechanism differs among the individual compounds.

Animals↗
PubMed1999

Enhancement of expression and apparent secretion of Erwinia chrysanthemi endoglucanase (encoded by celZ) in Escherichia coli B.

Escherichia coli B has been engineered as a biocatalyst for the conversion of lignocellulose into ethanol. Previous research has demonstrated that derivatives of E. coli B can produce high levels of Erwinia chrysanthemi endoglucanase (encoded by celZ) as a periplasmic product and that this enzyme can function with commercial fungal cellulase to increase ethanol production. In this study, we have demonstrated two methods that improve celZ expression in E. coli B. Initially, with a low-copy-number vector, two E. coli glycolytic gene promoters (gap and eno) were tested and found to be less effective than the original celZ promoter. By screening 18,000 random fragments of Zymomonas mobilis DNA, a surrogate promoter was identified which increased celZ expression up to sixfold. With this promoter, large polar inclusion bodies were clearly evident in the periplasmic space. Sequencing revealed that the most active surrogate promoter is derived from five Sau3A1 fragments, one of which was previously sequenced in Z. mobilis. Visual inspection indicated that this DNA fragment contains at least five putative promoter regions, two of which were confirmed by primer extension analysis. Addition of the out genes from E. chrysanthemi EC16 caused a further increase in the production of active enzyme and facilitated secretion or release of over half of the activity into the extracellular environment. With the most active construct, of a total of 13,000 IU of active enzyme per liter of culture, 7,800 IU was in the supernatant. The total active endoglucanase was estimated to represent 4 to 6% of cellular protein.

Base Sequence↗
PubMed1999

Flow cytometric analysis of BHRF1 expression prohibiting apoptosis induced by radiation.

The Epstein-Barr virus gene BHRFI has homology with proto-oncogene bcl-2, which can protect cells from apoptosis. In order to investigate the effect of BHRF1 expression on the anti-apoptotic ability of nasopharyngeal carcinoma (NPC) cells after irradiation, a high-BHRF1 expression vector was constructed and transfected into the NPC cell line CNE2. Then, the alteration of proliferation and apoptosis in the cells was tested by flow cytometry after cobalt 60 irradiation. The results showed that BHRF1 expression could increase G1 delay and decrease the cell percentage in S phase before irradiation, and reduce the apoptotic rate of CNE2 cells and increase the cell percentage in S phase after irradiation. The results suggest that BHRF1 expression is able to alter the cell cycle and protect CNE2 cells from apoptosis induced by radiation.

Apoptosis↗
PubMed1999

Substance use and its relationship to depression, anxiety, and isolation among youth living with HIV.

Reductions from lifetime to recent levels of substance use, the time since HIV diagnosis, physical health symptoms, CD4 counts, emotional distress, and social supports were examined among 227 (20% female; 22% African American, 27% Anglo, 35% Latino) youth living with HIV (YLH) ages 13 to 24 years. Substance use pervaded the lives of these youth. Male YLH had used more drugs., more often, and for longer periods than women. However, there had been major reductions in use. Being male, having high emotional distress, and having fewer negative social supports were significantly associated with greater reductions in substance use. There was a trend for the length of time that an individual was seropositive being associated with reductions in substance use. The counterintuitive findings suggest that there must be a re-examination of the role of the social support networks of youth living with HIV, as well as the ways in which emotional distress interacts with risk behaviors.

Journal Article↗
PubMed1999

[Research on the influences that affect the physician's perception of discharge summaries. A survey of outpatient department physicians].

The object of this study was to improve the completion of discharge summaries. The purpose of this article is: 1. to describe the perceptions of outpatient department physicians as to whether incomplete discharge summaries affect outpatient medical care or not, and 2. to elucidate the factors contributing to their perceptions. The physicians were randomly selected from among "the National Certified Training Hospitals" and "Japan Society for Quality in Health Care", and the size of the hospitals, the medical record management system and the format of the discharge summary were chosen for analysis of the factors that affect physicians' perceptions. Of the 2,304 questionnaires sent, 935 (40.6%) were returned. The results showed that 832 (89.0%) of the physicians thought that outpatient medical care would be affected if discharge summaries were not completed. Based on the analysis of the factors affecting the perceptions of the physicians, there was a trend showing that the influence was lower in small hospitals (p < 0.05), that the centralized management system for medical records had a higher influence (p < 0.05), and that the format of the discharge summary also affects physician's perceptions (p < 0.05).

Ambulatory Care↗
PubMed1999

Therapeutic resistance: characterization and inactivation by specific antiserum of a putative protein family produced by tumour cells.

A multitherapy resistance (MTR) factor produced by Cloudman S91 mouse melanoma cells rescues a responsive cell line after gamma-irradiation, short wavelength ultraviolet light, mitomycin C, vinblastine and actinomycin D. A similar activity with respect to ionizing radiation is now shown to be produced by human melanoma cells and by both human and mouse breast cancer cells but not by five normal cell lines. In these studies, the factor produced in serum-free conditioned medium (SFCM) by Cloudman S91/I3 cells is further characterized. Its activity in a clonogenic assay using related Cloudman S91/amel cells is destroyed by trypsin but not by DNase and is stable for at least 8 days at a variety of temperatures including 37 degrees C. Molecules greater than 30 kDa from SFCM collected from S91/I3 cells were concentrated and separated by preparative zonal electrophoresis (PZE). Bioactivity was present in both the cathode- and the anode-running fractions. The active acidic (anode) fractions were analysed by preparative isoelectric focusing. Bioactivity was present between pI 3.5 and 4.2. These PZE fractions were also used to immunize two rabbits, both of which produced antiserum that abrogated the bioactivity of SFCM and of the PZE cathode fractions. Antiserum also decreased the survival of irradiated S91/I3 producer cells that do not respond to SFCM but nonetheless must require MTR proteins for the expression of radiation resistance. These studies present a model for the production of rescue factors by non-clonogenic tumour cells that may persist in some tumours for considerable periods of time.

Amino Acid Transport Systems, Neutral↗
PubMed1999

[Cytotoxicities of low dose anticancer agents combining lymphokine activated killer cell against ovarian adenocarcinoma cell line SKOV3].

OBJECTIVE: To investigate whether low-dose anticancer agents could increase the sensitivity of ovarian adenocarcinoma cell line SKOV3 to lymphokine activated killer cell (LAK). METHODS: After SKOV3 cells were pretreated by low dose anticancer agents Taxol, cis-diamminedichloroplatin(CDDP), 5-fluorouracilum(5-FU) for 18 hours, the sensitivity of SKOV3 to LAK was detected by four 51Cr release assay. And the percentage of SKOV3 adhesion to LAK and intercellular adhesion molecule-1 (ICAM-1) expression on SKOV3 were detected by improved Grimm's assay and FACS respectively. RESULTS: After pretreatment of SKOV3 cell with 1.5 micrograms/ml Taxol, 4 micrograms/ml CDDP, 25 micrograms/ml 5-FU or without anticancer agents as control for 18 hours, the cytotoxicities of Interleukin-2 activated LAK against them were 29.7%, 45.9%, 37.2% and 28.5% respectively. The conjugation rates of SKOV3 and LAK were 20.1%, 26.1%, 24.9% and 18.7% respectively. The positive rates of ICAM-1 expression were 52.5%, 65.5%, 68.1% and 49.7% respectively. CDDP and 5-FU increased ICAM-1 expression significantly and the sensitivity of SKOV3 cell to LAK cell lysis was well related to the ICAM-1 expression. CONCLUSION: The results indicate that some low dose anticancer agents can increase the sensitivity of cancer cells to LAK cells and it would be useful in clinical practice.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

[Condition and mechanism of host antiinfect capacity induced by bypass-activated complement: experimental study].

OBJECTIVE: To verify host antiinfect capacity induced by bypass-activated complement. METHODS: A monolayer culture of human PMNs and rats kupffer cells (KCs) were added with zymosan-activated human serum (ZAHS) and 3 parameters were measured. ZAHS had been neutralized in tube with antiserum against human C3 and C5. RESULTS: In 0.07-0.09 ml ZAHS and 1-3 h, intracellular bactericidal activity (ICBA) showed a peak but significant top value at 2nd hour. The value dropped markedly with time and significantly in 4-6 h. Superoxide ions (O2-) dynamics was similar to ICBA. Acid phosphatase (ACP) curve distinguished from the former's with monotonous decrease (1-6 h) and more deep. With 0.11 ml ZAHS after 4 h, about 80% of KCs were fallen off. Three parameters of PMNs were decreased and reached the lowest point in the 6th hour after the adding 0.05-0.09 ml of ZAHS. After blocking test with antihuman C3 and C5 serum, the values of ICBA, O2- and ACP surpassed those in the experimental group. CONCLUSION: The possible mechanism of the origination of the harmful effects of ZAHS is suggested. Before KCs and PMNs undertake phagocytosis, they release the bactericidal and inflamagenic (O2- and ACP) so the intracellular bactericidal activity of KCs and PMNs are decreased. The accumulation of KCs and PMNs in tissues can damage themselves and the adjacent tissues barrier, which will lead to the occurrence of infection.

Animals↗
PubMed1999

[Preliminary study on the immune response in C57BL/6 mice vaccinated by nucleic acid encoding paramyosin of Chinese S. japonicum].

OBJECTIVE: To study the characteristics of immune response in C57 BL/6 mice by nucleic acid encoding full-length paramyosin of Chinese S. japonicum. METHODS: Total RNA was isolated from adult Chinese S. japonicum using TRIzol reagent. The full-length cDNA encoding paramyosin of Chinese S. japonicum was amplified by RT-PCR and cloned into expression vector pcDNA/Amp (pCMV-SjC97), which was intramuscularly injected into C57 BL/6 mice. The mice were vaccinated with DNA the three-week interval for a total of three inoculations. The specific anti-SjC97 IgM, IgG and IgE antibodies and IgG subclasses were determined by ELISA test. RESULTS: The pCMV-SjC97 vaccine induced specific anti-SjC97 IgM and IgG antibodies. The antibody response correlated well with the administered amount of pCMV-SjC97. The IgG subclasses, predominantly IgG2a and IgG2b, were observed in the mice vaccinated with pCMV-SjC97, but no IgG1 and IgG3 responses were seen. CONCLUSION: The strong immune response, especially Th1 type, can be induced in the mice with pCMV-SjC97 vaccine.

Animals↗
PubMed1999

[The comparison of bone densities of mandible and coxofemoral region between senile people with edentulous jaws and those with dentate jaws].

OBJECTIVE: To observe if the senile people with edentulous jaws had lower bone dentilies of mandible and coxofemoral region than those with dentate jaws, and to find the systemic risk factors which were responsible for the tooth loss and the formation of edentulous jaws. METHODS: Two groups of senile people were selected. One group was edentulous and the other was dentate. All of them were examined by dual energy X-ray absorptiometry(DXA). RESULTS: The senile people with edentulous jaws had significantly lower bone densities of mandible(P < 0.001) and they also had lower bone densities of coxofemoral region than the dentate group people. CONCLUSION: It indicated that the decreased of bone densities of mandible and coxofemoral region was one of the systemic risk factors for tooth loss and the formation of edentulous jaws.

Age Factors↗