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Biomedical subjects

Y Gong

Publications and source records attributed to Y Gong.

At least 55 records · Page 3Linked to original sources
PubMed2001

Changes of absorption spectra during heat-induced denaturation of Photosystem II core antenna complexes CP43 and CP47: revealing the binding states of chlorophyll molecules in these two complexes.

The Photosystem II (PSII) core antenna complexes, CP43 and CP47, were prepared from spinach (Spinacia oleracea L.). The absorption spectra in the red region at room temperature were recorded for the PSII core antenna samples after increased temperature treatment (up to 80 degrees C). Derivative and difference spectra revealed the existence of two groups of chlorophyll a (Chl a) molecules in both CP43 and CP47. The one with the absorption peak in the shorter wavelength region was designated as CP43-669 and CP47-669, while the other with the absorption peak in the longer wavelength region was designated as CP43-682 and CP47-680. The results of the thermal treatment experiment demonstrated that CP43-669 and CP47-669 may exist as monomers of Chl a and that their binding sites on the polypeptides are insensitive to thermal treatment, whereas CP43-682 and CP47-680 may exist as dimers or multimers of Chl a and their binding regions in the polypeptide chains are more sensitive to heat treatment. The excitation energy transfer mechanism between these two different groups of Chl a molecules is also analyzed.

Apoproteins↗
PubMed2001

Conversion of Glu-plasminogen to Lys-plasminogen is necessary for optimal stimulation of plasminogen activation on the endothelial cell surface.

When Glu-plasminogen is bound to cells, plasmin (Pm) formation by plasminogen (Pg) activators is markedly enhanced compared with the reaction in solution. It is not known whether the direct activation of Glu-Pg by Pg activators is promoted on the cell surface or whether plasminolytic conversion of Glu-Pg to the more readily activated Lys-Pg is necessary for enhanced Pm formation on the cell surface. To distinguish between these potential mechanisms, we tested whether Pm formation on the cell surface could be stimulated in the absence of conversion of Glu-Pg to Lys-Pg. Rates of activation of Glu-Pg, Lys-Pg, and a mutant Glu-Pg, [D646E]Glu-Pg, by either tissue Pg activator (t-PA) or urokinase (u-PA) were compared when these Pg forms were either bound to human umbilical vein endothelial cells (HUVEC) or in solution. ([D646E]Glu-Pg can be cleaved at the Arg(561)-Val(562) bond by Pg activators but does not possess Pm activity subsequent to this cleavage because of the mutation of Asp(646) of the serine protease catalytic triad.) Glu-Pg activation by t-PA was enhanced on HUVEC compared with the solution phase by 13-fold. In contrast, much less enhancement of Pg activation was observed with [D646E]Glu-Pg ( approximately 2-fold). Although the extent of activation of Lys-Pg on cells was similar to that of Glu-Pg, the cells afforded minimal enhancement of Lys-Pg activation compared with the solution phase (1.3-fold). Similar results were obtained when u-PA was used as activator. When Glu-Pg was bound to the cell in the presence of either t-PA or u-PA, conversion to Lys-Pg was observed, but conversion of ([D646E]Glu-Pg to ([D646E]Lys-Pg was not detected, consistent with the conversion of Glu-Pg to Lys-Pg being necessary for optimal enhancement of Pg activation on cell surfaces. Furthermore, we found that conversion of [D646E]Glu-Pg to [D646E]Lys-Pg by exogenous Pm was markedly enhanced ( approximately 20-fold) on the HUVEC surface, suggesting that the stimulation of the conversion of Glu-Pg to Lys-Pg is a key mechanism by which cells enhance Pg activation.

Cell Membrane↗
PubMed2001

High-level expression and purification of immunogenic recombinant SAG1 (P30) of Toxoplasma gondii in Escherichia coli.

Surface antigen 1 (SAG1) of Toxoplasma gondii is a good candidate for diagnosis and vaccine development, but recombinant SAG1 produced in Escheichia coli often loses its specific immunogenicity due to the incorrect folding. In the present study, a truncated SAG1 was highly expressed in E. coli as a fusion protein, about 30% of the total protein of the cell lysate. After a simple purification and refolding procedure, purified rSAG1 can be recognized by human Toxoplasma-infective serum, and ELISA kits constructed by rSAG1 can sensitively and specifically detect toxoplasma infection.

Animals↗
PubMed2001

Preclinical evaluation of docusate as protective agent from herpes simplex viruses.

Prevention of sexually transmitted infections (STIs) is key to public health efforts to control these diseases. An effective vaginal microbicide could provide topical, broad-spectrum prevention against the transmission of several STI pathogens. Docusate is a sulfated surfactant and, as such, may inactivate viral pathogens by disrupting viral envelopes and/or denaturing/disassociating proteins. Accordingly, the in vitro efficacy and toxicity of docusate (dioctyl sodium sulfosuccinate; Zorex; Meditech Pharmaceuticals, Inc., Scottsdale, Arizona) against herpes simplex viruses (HSV) were evaluated. Docusate was effective in vitro against wild type and drug-resistant strains of HSV type 1 and 2 with EC(90-100) (effective concentration giving 90-100% virus yield reduction) of approximately 0.005% (w/v). Sodium dodecyl sulfate (SDS) was equipotent, however, docusate was somewhat less toxic to uninfected Vero cells compared with SDS after 2 days incubation (docusate CC(50) approximately 0.01% vs. SDS approximately 0.005%). The cytotoxicity profiles of docusate were time- and dose-dependent and thus associated with the frequency of use. Kinetics of inactivation examined by pre-mixing virus and drug in a time-course experiment demonstrated that docusate could reach its EC(90-100) within 30 min. Docusate pretreatment of cells was associated with a 45% reduction in infectivity of those cells, despite a triple washing procedure. Once infected, an approximate 30% plaque reduction was observed with treatment.

Animals↗
PubMed2001

Immediate-early protooncogene expression and liver function following various extents of partial hepatectomy in the rat.

Immediate-early protooncogenes (IEP) are thought to play an important role in hepatocyte replication. Whether the extent of their expression correlates with the strength of the proliferative stimulus and subsequent regenerative activity has yet to be documented in vivo. Data are also lacking with respect to the level at which liver disease is associated with biochemical evidence of hepatic dysfunction. Thus, the objectives of this study were to determine whether a correlation exists between IEP gene mRNA expression and varying extents of partial hepatectomy (PHx) and to document the extent of resection required to result in increases in serum bilirubin levels. Eighty-nine adult, male Sprague-Dawley rats underwent either sham surgery or 20%, 35%, 55%, 70% or 90% PHx. Postoperatively, rats were killed (N = 3-6/group) at 15 and 30 mins and 8 and 24 hrs for c-fos, c-jun, and c-myc mRNA expression by northern blot analyses. Rats killed at 24 hrs also had hepatic regenerative activity documented by [3H]thymidine incorporation into hepatic DNA and serum bilirubin determinations. While c-fos mRNA expression at 15 mins and c-myc mRNA expression at 8 hrs after PHx did not correlate with the extent of PHx (r2 = 0.478 and 0.018, respectively), a weak correlation existed between c-jun mRNA expression at 30 mins and the extent of PHx (r2 = 0.662, P < 0.05). In terms of IEP mRNA expression and hepatic regenerative activity, a strong correlation existed between c-fos mRNA expression and [3H]thymidine incorporation (r2 = 0.851, P < 0.01) but not c-jun or c-myc mRNA expression. Compared to sham operated controls, [3H]thymidine incorporation was 2.0x, 3.4x, 3.2x, 7.8x, and 2.2x increased following 20%, 35%, 55%, 70%, and 90% PHx, respectively. Serum bilirubin levels remained unchanged until 70% PHx, when they increased from baseline values of 0.54+/-0.05 mg/dl to 1.02+/-0.15 mg/dl (P < 0.05). A further increase occurred following 90% PHx (1.83+/-0.30 mg/dl, P < 0.01). In conclusion these findings indicate that c-fos mRNA expression 15 mins after PHx correlates with hepatic regenerative activity but not the strength of the regenerative stimulus and that hepatic parenchymal loss of 55-70% must occur prior to the detection of elevated serum bilirubin levels. The results also indicate that relative to a 70% PHx, 90% PHx is associated with decreased rather than increased hepatic regenerative activity.

Animals↗
PubMed2001

Role conflict and ambiguity of CEOs in international joint ventures: a transaction cost perspective.

Insights from transaction cost economics were used to study the boundary conditions underlying the role conflict and ambiguity of 265 CEOs in Chinese-based international joint ventures. Role conflict and ambiguity were lower when the contract between parents was more complete. Contract completeness fully mediated the effects of parent objective gap and parent formalization on role ambiguity but only partially so in the case of role conflict. Role conflict was lower when the foreign parent was dominant in the venture but higher when the local parent was dominant. Role conflict and ambiguity were inversely related to cultural distance. Neither construct had a detrimental effect on international joint venture performance. Implications for role theory are discussed.

Administrative Personnel↗
PubMed2001

Osteopontin gene is expressed in the dermal papilla of pelage follicles in a hair-cycle-dependent manner.

Hair follicle formation and maintenance involve intimate interactions between follicular epithelial cells and a group of specialized mesenchymal cells known as the dermal papilla. Using the random primer polymerase chain reaction, we have identified an approximately 1.4 kb osteopontin mRNA that is present in large quantities in cultured rat vibrissa dermal papilla cells but undetectable in cultured rat skin fibroblasts. In situ hybridization showed that the osteopontin gene is expressed in dermal papilla cells of pelage follicles during catagen but not in anagen or telogen. As an acidic glycosylated RGD-containing extracellular matrix protein, osteopontin can function both as a cell attachment protein and as a soluble cytokine playing roles in signaling, cell migration, tissue survival, anti-inflammation, and T-cell-mediated cellular immunity. Our results indicate that the comparison of the mRNA of cultured dermal papilla cells and fibroblasts can lead to the identification of not only anagen-specific genes (e.g., nexin 1), but also a catagen-specific gene. We have thus provided evidence that specific genes are turned on during catagen, which is therefore not simply a passive "degenerative" phase. The functional role of osteopontin in catagen is unclear but it may promote the formation of a tightly aggregated dermal papilla, and/or protect the dermal papilla cells from apoptosis induced by cytokines or hypoxia during catagen.

Alopecia↗
PubMed2001

Electrolyte effects on electrochemical properties of osmium complex polymer modified electrodes.

The electrolyte effects on the electrochemical behaviors of osmium complex polymer modified electrodes were investigated by a comparison between two osmium complexes, [Os(bpy)2(PVI)10Cl]Cl (Os-PVI10) and [Os(bpy)2(PVP)10Cl]Cl (Os-PVP10). The electrode process at Os-PVI10 modified electrodes is reaction-controlled, while a diffusion-controlled electrode process exists at Os-PVP10 modified electrodes. Both the cation and anion in supporting electrolytes strongly affect their electrochemical behaviors, such as the redox potential, wave shape and peak current. These phenomena are attributed to a change in the film structure and polymer swelling in various supporting electrolytes. The influence of electrolyte anions on the electrochemical behaviors is related to their hydrophobicity. The electrode process of Os-PVP10 depends on the pH value of solutions, exhibiting different electron transfer mechanisms.

Journal Article↗
PubMed2001

[The construction of rapid amplification of cDNA ends cDNA libraries from human fetal bone and joint].

OBJECTIVE: To construct rapid amplification cDNA ends(RACE) cDNA libraries from human fetal bone and joint and provide resources for isolation of bone- and joint-specific development-related genes. METHODS: Total RNA of bone and joint were extracted with the modified single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. The double-stranded end-blunted cDNA were synthesized using TaKaRa's cDNA synthesis kit and ligated to cassette adaptors. All of the cDNA molecules were amplified by a pair of common primers. RESULTS: A protocol for RACE cDNA library construction from bone and joint was established and two RACE cDNA libraries from human fetal bone and joint were successfully constructed. CONCLUSION: The protocol of RACE cDNA library construction from limited materials proved to be simple and efficient and the library was suitable for RACE to isolate tissue-specific genes.

Bone and Bones↗
PubMed2001

[Analysis on genetic polymorphism of 13 STR loci on chromosomes 11 and 19 in Chinese Hans].

OBJECTIVE: To analyze the genetic polymorphism of 8 STR loci on chromosome 11 and 5 STR loci on chromosome 19 in Chinese Hans. METHODS: Polymerase chain reaction-single strand length polymorphism(PCR-SSLP) was used to genotype 100 randomly selected individuals of the Han nationality at 8 STR loci(D11S1984, D11S1999, D11S1392, D11S1985, D11S2002, D11S1986, D11S4464 and D11S2359) on chromosome 11 and 5 STR loci(D19S247, D19S714, D19S433, D19S246, D19S254) on chromosome 19. RESULTS: Eight alleles and 26 genotypes, 9 alleles and 15 genotypes, 6 alleles and 16 genotypes, 12 alleles and 40 genotypes, 6 alleles and 19 genotypes, 12 alleles and 48 genotypes, 8 alleles and 20 genotypes, 7 alleles and 13 genotypes were observed at D11S1984, D11S1999, D11S1392, D11S1985, D11S2002, D11S1986, D11S4464 and D11S2359. The heterozygosities for the 8 STR loci were 87%, 68%, 73%, 92%, 71%, 86%, 75% and 71%, respectively. Ten alleles and 19 genotypes, 10 alleles and 26 genotypes, 10 alleles and 24 genotypes, 11 alleles and 29 genotypes, 8 alleles and 18 genotypes were observed at D19S247, D19S714, D19S433, D19S246, D19S254. The heterozygosities for the 5 STR loci were 63%, 82% 72%, 81% 74%, respectively. CONCLUSION: The distribution of allele frequencies of 8 STR loci on chromosome 11 and 5 STR loci on chromosome 19 was consistent with the Hardy-Weinberg equilibrium and the highly genetic polymorphism was observed in Chinese Han population.

China↗
PubMed2001

[Factors allowing continuous working of female nurses in the People's Republic of China--survey of 15 hospitals in 5 areas].

PURPOSE: Few investigations have been conducted on working, childcare and home education among female nurses (nurses) in the People's Republic of China (P.R. of China). The purpose of this study was to clarify the factors allowing continued working of female nurses. METHODS: The subjects were nurses from 15 hospitals in 3 provinces and 2 autonomous areas. They were surveyed by questionnaire regarding their childcare and home education. In was distributed by the Ministry of Health in the P.R. of China and the data were collected between February and April in 1996. RESULTS: A total of 4,284 (80.0%) questionnaires were collected. 1. About 60% of the nurses began working when they were 15 to 19 years old. The average length of service was 13.9 years. 2. Their professional position correlated directly with their years of service. 3. 4.3% of them had not continued working. 4. The nurses entrust their children to day-care institutions (61.2%) or grandparents (22.3%) during the daytime, and to the father (66.3%) or the grandparents (19.5%) during the night. 5. 17.6% of them have experienced being away from home for more than one month due to their job. 6. 66.8% of the nurses have experienced more than one month official trip, and had children under 14 years old at the time. They entrusted their children to day-care institutions (34.1%), to the father (29.2%) and grandparents (25.3%) during the official trip. CONCLUSIONS: In summary, most nurses are employed when they are young and go on working as nurses. It is possible for them to continue their work after marriage, childbirth, and while they are bringing up their children. The high rate of working woman, sufficient nursery schools and family cooperation in housework can be pointed out as main factors that enable them to continue their work.

Adolescent↗
PubMed2001

[Childcare and home education in families of female nurses in the People's Republic of China--survey of 15 hospitals in 5 areas].

PURPOSE: The purpose of this study was to investigate the actual conditions of childcare and home education among families of female nurses in the P. R. of China. METHODS: The subjects were nurses from 15 hospitals in 3 provinces and 2 autonomous areas. They were surveyed by questionnaire regarding their childcare and home education. It was distributed by the Ministry of Health in the P. R. of China and data were collected between February and April in 1996. RESULTS: A total of 4284 (80.0%) questionnaires were collected. 1. The age of the subjects was between 18 and 62 years old with a mean of 32.9 +/- 9.0 (SD) years 71.4% of them had husbands, whose ages were between 23 and 71 years old, the mean age being 38.3 +/- 8.4 (SD) years. The family types were 63.2% nuclear family and 33.7% extended family, with 3.1% being single. 65.1% of the subjects had children, whose mean number was 1.1 +/- 0.4 (SD). Firstborn children were 49.9% girls and 50.1% boys. 2. The most popular method of infant nutrition was breast-feeding, utilized by 60.1%. The highest rate (67.8%) was in the age group of 25 to 29 years old (P < 0.01). 3. The practice of "swaddling" (wrapping the child so as not to allow movement) was more common in the over 40 year old age group than the under 40 year old group (P < 0.01). Swaddling-practice showed significant differences by area. 4. The rates for children who helped with housework were 50.3% for girls and 46.7% for boys. 5. A number of children between 7 and 18 years old were studying English privately. 6. The greatest expectation of the subjects, for their children aged between 7 and 18 years old, was to study. CONCLUSIONS: 1. Infant nutrition showed significant differences between generations, and swaddling-practice differed with the generation and the area. 2. Although girls help their parents more than boys in Japan, boys and girls equally helped their parents in the P. R. of China. 3. Concerning the topics of private learning and parents expectations, the results were similar to those in Japan.

Adolescent↗
PubMed2001

[Analysis of relationship between risk factors of malignant transformation of oral leukoplakia and the LSCP system].

OBJECTIVE: To explore the clinical significance of the LSCP (lesion size, site of lesion, clinical aspects, pathological aspects) classification and staging system through a comprehensive analysis of relationships between the risk factors of malignant transformation of 209 cases with oral leukoplakia and the LSCP classification and staging system. METHODS: Single factor Chi-square test was first performed to examine the associations between LSCP stages (I, II, III, IV) of oral leukoplakia and each of risk factors, including sex, site, size, numbers of lesion, alcohol and tobacco consumption, clinical classification and histopathological classification respectively, to select the most significant factors which influence the LSCP classification and staging. Then, the association of these selected factors with LSCP stages of oral leukoplakia (stage IV vs. I, II and III) was evaluated using multiple logistic regression analysis. RESULTS: Sex, site of lesions, clinical aspect and histopathological features of lesions were chosen as risk factors incorporated into the multiple logistic regression models. The results demonstrated that the risk of oral leukoplakia of the female patients classified as LSCP stage IV was 2.49 times as high as that of the male patients. The risk of lesions occurring in tongue and/or that floor of mouth was higher than that in other sites. Among the different clinical subtypes of lesions, the verrucous leukoplakia was the highest and 10.00 times as high as that of the homogeneous one. Among the different histopathological types, when hyperplasia and mild dysplasia were set as the basic level, the risk of severe dysplasia classified as LSCP stage IV was the highest and 499.55 times as high as the basic level, while that of moderate dysplasia was 276.48 times as high as the basic level. Pathological features with moderate and severe dysplasia were the most important contributory factors to the LSCP staging. CONCLUSIONS: The LSCP classification and staging system provides a comprehensive description of the features of oral leukoplakia, which is helpful in evaluating the overall risk of malignant transformation of oral lesion, and is valuable in clinical follow-up and developing the best treatment plan.

Adult↗
PubMed2001

[Subcellular distribution of daunorubicin in the P-glycoprotein-mediated multidrug-resistant cell line K562/ADR].

OBJECTIVE: To examine subcellular distribution of daunorubicin (DNR) in P-glycoprotein-mediated multidrug-resistant cell line K562/ADR and its relation to multidrug resistance. METHODS: The subcellular distribution of DNR in K562/ADR was studied by confocal scanning laser microscopy (CSLM), fluorometry, RT-PCR. Rhodamine 123, NBD-ceramide and neutral red as fluorescent probes to stain the mitochondria, Golgi apparatus and lysosomes respectively were used to identify the subcellular compartments wherein DNR was sequestered. Effect of verapamil, chloroquine and brefeldin A on DNR distribution and accumulation was examined. RESULTS: Compared with the drug-sensitive cell K562/S in which DNR fluorescence diffusely appeared in the nucleus and cytoplasm, DNR in K562/ADR cells was distributed to the perinuclear region and peripheral cytoplasm, It was scenty in the nucleus and other cytoplasmic regions, as suggested by the distribution of Rhodamine123. Only verapamil, but not chloroquine and brefeldin A, could markedly restore diffuse cytoplasmic and nuclear fluorescence distribution in the resistant cell line. CONCLUSION: Altered subcellular distribution of DNR in drug resistant cell line may participate in the generation of multidrug resistance in which P-glycoprotein plays an important role.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

[Expression of a snake venom plasminogen activator TSV-PA in insect cells].

A snake venom gene TSV-PA was inserted into the donor plasmids pFastBacHTa and expressed in Tn-5B1-4 cells. SDS-PAGE analysis revealed that the molecular weight of expressed product of TSV-PA were 33 kD. It was also proved by Western blot. The result of enzyme activity showed that TSV-PA protein expressed in insect cells had a higher activity.

Animals↗
PubMed2001

[The bottleneck steps limiting maturation of penicillin G acylase in Escherichia coli].

We have identified the bottleneck steps limiting maturation of penicillin G acylase (PAC) through comparison of the maturation performance for various PAC-expression systems (Pac, Tac, T7, Vgb + T7) with different efficiencies of proteolysis, subunit folding and assembly. The maturation of PAC could be limited by various steps, such as translocation, periplasmic proteolysis, subunit folding and assembly depending on the host/vector systems. In BL21(pPA6) cells, maturation of PAC were limited by proteolysis and folding steps; the efficiency of proteolysis was 57.2%; the subunit folding and assembly capacity was 0.72. In BL21(pKKpacSP) cells, the stability and folding of alpha subunit was bottleneck steps. In T7 and dissolved-oxygen regulation expression systems, PAC proprecursor could be maturated efficiently. Results also indicate that the folding of alpha peptide plays a key role in folding of precursor for PAC in E. coli. Developing proper host/vector systems and fermentation technology with superior abilities on subunit folding and assembly of precursor for PAC could be plausible for enhancing production of PAC. In this study, pac could be expressed (transcribed, translated and maturated) efficiently under the control of T7 promoter.

Enzyme Precursors↗