Biomedical subjects

H Gu

Publications and source records attributed to H Gu.

At least 55 records · Page 3Linked to original sources

PubMed2000

Impact of stressful life events, depression, social support, coping, and cortisol on progression to AIDS.

OBJECTIVE: This study examined prospectively the effects of stressful events, depressive symptoms, social support, coping methods, and cortisol levels on progression of HIV-1 infection. METHOD: Eighty-two homosexual men with HIV type-1 infection without AIDS or symptoms at baseline were studied every 6 months for up to 7. 5 years. Men were recruited from rural and urban areas in North Carolina, and none was using antiretroviral medications at entry. Disease progression was defined as CD4(+) lymphocyte count <200/microl or the presence of an AIDS indicator condition. RESULTS: Cox regression models with time-dependent covariates were used adjusting for race, baseline CD4(+) count and viral load, and cumulative average antiretroviral medications. Faster progression to AIDS was associated with higher cumulative average stressful life events, coping by means of denial, and higher serum cortisol as well as with lower cumulative average satisfaction with social support. Other background (e.g., age, education) and health habit variables (e.g., tobacco use, risky sexual behavior) did not significantly predict disease progression. The risk of AIDS was approximately doubled for every 1.5-unit decrease in cumulative average support satisfaction and for every cumulative average increase of one severe stressor, one unit of denial, and 5 mg/dl of cortisol. CONCLUSIONS: Further research is needed to determine if treatments based on these findings might alter the clinical course of HIV-1 infection.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Adsorption of bilirubin by amine-containing crosslinked chitosan resins.

Crosslinked chitosan resin, which has good blood compatibility, was prepared by crosslinking chitosan solution with glutaraldehyde. Polymeric adsorbents for bilirubin have been synthesized by chemical modification of crosslinked chitosan resins with di-, tri-, tetra-, and pentammines. The adsorption of bilirubin on the adsorbents was investigated in detail. The results indicated that electrostatic interaction and hydrophobic interactions are the main driving forces for the adsorption. Compared with crosslinked chitosan resin, the functionalized chitosan beads have higher adsorption capacity for unconjugated and conjugated bilirubin.

Adsorption↗

PubMed2000

Effect of ATP-potassium channel opener nicorandil on long-term cardiac preservation.

BACKGROUND: ATP-sensitive potassium channels have been shown to be one of the important protective mechanisms for the ischemic myocardium. The purpose of this study was to evaluate the protective effect of nicorandil, an ATP-sensitive potassium channel opener, on myocardium during 6 hours hypothermic preservation. METHODS: Preserved rat hearts were randomly divided into 4 groups according to cardioplegia and preservation protocols as follows: (1) histidine-tryptophan-ketoglutarate solution (HTK) for both cardioplegic and immersing solutions (group A); (2) nicorandil-added HTK for cardioplegic solution and nicorandil-free HTK for immersing solution (group B); (3) nicorandil-free HTK for cardioplegic solution and nicorandil-added HTK for immersing solution (group C); and (4) nicorandil-added HTK for both cardioplegic and immersing solutions (group D). RESULTS: The recovery of postischemic cardiac function, including left ventricular developed pressure and end-diastolic pressure, was significantly improved in group B and group C as compared with the other groups (p<0.05). Postischemic intracellular calcium concentration was significantly lower in group B and group C than in group A (p<0.05). CONCLUSIONS: We concluded that nicorandil-induced hyperpolarizing arrest could reduce ischemia-derived myocyte injury and inhibit the influx of calcium into the myocytes in long-term cardiac preservation.

Animals↗

PubMed2000

[The expression of CD15 mRNA CD44v6 mRNA and nm23H1 mRNA in breast cancer and their clinical significance].

OBJECTIVE: To study the relationship of the expression of CD15 mRNA and its protein, CD44v6 mRNA and nm23H1 mRNA with the clinical pathology parameter and prognosis of breast cancer, and to investigate the correlation of the expression of CD15 mRNA with CD44v6 mRNA and nm23H1 mRNA. METHODS: Catalyzed signal amplification (CSA) method of in situ hybridization and immunohistochemistry were used to detect the expression of CD15 mRNA and its protein, CD44v6 mRNA and nm23H1 mRNA in 94 cases of breast cancer. RESULTS: The overexpression of CD15 mRNA and its protein and CD44v6 mRNA and the low expression nm23H1 mRNA were correlated with the grading, clinical stage, lymph node metastasis, recurrence and prognosis of breast cancer. Patients who had overexpression of CD15 mRNA and CD44v6 mRNA and low expression of nm23H1 mRNA had a higher lymph node metastatic rate and a lower survival rate. CONCLUSION: The expression of CD15 mRNA has a synergistic action in positive and negative regulation with that of CD44v6 mRNA and nm23H1 mRNA. Combining detection of the expression of these three mRNA is a reliable index to evaluate the metastasis, recurrence and prognosis of breast cancer.

Breast Neoplasms↗

PubMed2000

[An experimental study on F-heparin surface modified IOLs implanted into the Rhesus monkeys' eyes].

OBJECTIVE: To evaluate the biocompatibility of F-heparin surface modified IOLs. METHODS: 13 monkeys were divided into 3 groups, and implanted with different surface modified and non-modified IOLs into their eyes. All of the eyes were examined by slitlamp microscope and Schiötz tonometer at postoperative 15, 30, 60, 90 and 180 days. Postoperatively, at different periods the aqueous was aspirated from the anterior chamber to calculate cells. RESULTS: F-heparin surface modified IOLs induced milder inflammatory reaction and less dense posterior capsula opacification (PCO) than non-modified IOLs. CONCLUSION: F-heparin surface modified IOL has a better biocompatibility.

Animals↗

PubMed2000

[Primary study on immunologic effect of live attenuated hepatitis A vaccine (H2 strain) after booster dose].

OBJECTIVE: To study the immunologic effect of live attenuated hepatitis A vaccine (H(2) Strain, 10(7.0)TCID(50)) after booster and to compare with the results of 1 dose live attenuated hepatitis A vaccine (H(2) Strain, 10(7.0)TCID(50)). METHODS: 42 susceptibles with negative anti - HAV were selected in Zhengding, Hebei province. Each subject received 3 doses live attenuated hepatitis A vaccine at 0, 2, 6 months and was bled at 1, 2, 6, 7, 9, 12 months after vaccination. RESULTS: The seroconversion rate at 1 month after the first dose was 81.4% and reached 100% after the second dose. GMT arrived the peak 2,739 mIU/ml at one month after the third dose, before stared declining. The seroconversion rate kept 100% at 12 months after the first dose, but GMT decreased to 979 mIU/ml. CONCLUSION: The first dose worked as the base of boostering. A booster dose of live attenuated hepatitis A vaccine could induce secondary immune response well. The immunologic effect after booster dose could match the effect with inactivated vaccine and was better than the results of 1 dose live attenuated hepatitis A vaccine. The program seemed to be useful to the protective effect and the immuno - persistence.

Child↗

PubMed2000

[A case-control study on the risk factors of epidemic hemorrhagic fever].

OBJECTIVE: To study the risk factors of epidemic hemorrhagic fever (EHF). METHODS: A 1:1 matched case-control study was conducted to analyse EHF risk factors. RESULTS: One hundred and eighty-five matched pairs were investigated. Five factors were associated with risks of the disease, including rodent activity in house, farm working, travel, annual average income of an individual and ground material of the house, when chi(2) test and logistic regression model were processed respectively. The coefficients of rodent activity in house, farm working, travel, annual average income of an individual and ground material of the house in multivariable Logistic regression model were 1.377, 1.687, 1.630, -1.216 and -0.888, respectively, when P value < 0.05 was observed. CONCLUSIONS: Factors as high average income of individuals, brick or cement used as material of the ground in the house, seemed to be protective factors of EHF, which were important to the control and prevention of EHF.

Adult↗

PubMed2000

[Safety and immunogenicity of inactivated bivalent EHF vaccine in humans].

OBJECTIVE: Safety and immunogenicity of inactivated bivalent EHF vaccine in humans were evaluated in the epidemic area of Zhejiang province, China. METHODS: Susceptible persons with negative anti-EHF were selected in Jiande county, Zhejiang province to receive 3 doses of inactivated bivalent EHF vaccine at 0, 7, 28 days. A booster injection was given one year after the primary immunization. Antibody responses were measured in human volunteers by IFA and MCPENT. Local and general reactions were recorded within 72 hours after each vaccination by physicians. RESULTS: Two weeks after the primary vaccination, 99.04% of the subjects developed significant hantavirus antibody titre measured by IFA which had a 37.34% drop one year after the primary vaccination. Seroconversion rate increased to 100% two weeks after the booster dose. Neutralising antibody titres paralleled this trend with 100% of vaccine recipients producing neutralising antibody two weeks after the primary doses. However, it dropped to 80% one year after the primary vaccination. One hundred percent of the vaccine recipients started to respond two weeks after boosting. The geometric mean titre (GMT) of neutralising antibody against 76 - 118 and UR were 18.27 +/- 2.21 and 12.47 +/- 2.16 respectively after the primary injections, but it increased to 37.09 +/- 2.24 and 32.61 +/- 2.05 respectively after the secondary immunization. General and local reaction rates were 0.46% and 1.98%, with no severe side effects observed in the vaccinees. CONCLUSION: The vaccine was well tolerated and could induce good humoral immune response.

Antibodies, Viral↗

PubMed2000

[Effect of intravascular low level laser irradiation used in avulsion injury].

OBJECTIVE: To explore the effect of intravascular low level He-Ne laser irradiation on skin flap survival after orthotopic transplantation in avulsion injury. METHODS: Fifty eight cases suffered avulsion injury were treated by debridement and orthotopic transplantation of avulsed flap within 6 hours, 31 of them were received intravascular low level He-Ne laser irradiation and routine treatment, and 27 of them were received routine treatment as control group. RESULTS: The survival area and quality of avulsed flap in the experimental group were superior to that of control group after 15 days of operation, and the hemorheological items were markedly changed at 5 days after operation. CONCLUSION: The better flap survival after orthotopic transplantation in avulsion injury can be improved by intravascular low level He-Ne laser irradiation through changed superoxide dismutase activity and hemorheological items in optimal irradiation intensity.

Accidents, Traffic↗

PubMed1999

The role of external loop regions in serotonin transport. Loop scanning mutagenesis of the serotonin transporter external domain.

Chimeric transporters were constructed in which the predicted external loops of the serotonin transporter (SERT) were replaced one at a time with a corresponding sequence from the norepinephrine transporter (NET). All of the chimeric transporters were expressed at levels equal to or greater than those of wild type SERT, but the transport and binding activity of the mutants varied greatly. In particular, mutants in which the NET sequence replaced external loops 4 or 6 of SERT had transport activity 5% or less than that of wild type, and the loop 5 replacement was essentially inactive. In some of these mutants, binding of a high affinity cocaine analog was less affected than transport, suggesting that the mutation had less effect on the initial binding steps in transport than on subsequent conformational changes. The more severely affected mutants also displayed an altered response to Na(+). In contrast to the dramatic reduction in transport and binding, the specificity of ligand binding was essentially unchanged. Chimeric transporters did not gain affinity for dopamine, a NET substrate, or desipramine, an inhibitor, at the expense of affinity for serotonin or paroxetine, a selective SERT inhibitor. The results suggest that external loops are not the primary determinants of substrate and inhibitor binding sites. However, they are not merely passive structures connecting transmembrane segments but rather active elements responsible for maintaining the stability and conformational flexibility of the transporter.

Base Sequence↗

PubMed1999

The poly(A)-limiting element is a conserved cis-acting sequence that regulates poly(A) tail length on nuclear pre-mRNAs.

Most vertebrate mRNAs exit the nucleus with a 200+-residue poly(A) tail and are deadenylated to yield heterogeneous polymers of 50-200 adenosine residues on any given mRNA. We previously reported that Xenopus albumin mRNA and pre-mRNA have an unusually short, discrete 17-residue poly(A) tail and showed that regulation of poly(A) length is controlled independently by two cis-acting poly(A)-limiting elements (PLE A and PLE B) located in the terminal exon. The present study sought to determine the generality of this regulatory mechanism. Transferrin mRNA also has a discrete <20-nt poly(A) tail, and deletion mapping experiments identified an element homologous to the albumin gene PLE B within the terminal exon of the transferrin gene that conferred poly(A) length regulation on a globin reporter mRNA. Based on this similarity the PLE B sequence was used in a database search to identify candidate mRNA targets for regulated polyadenylation. Of the several hundred sequences identified in this manner we focused on HIV-EP2/Schnurri-2, a member of a family of genes encoding related zinc finger transcription factors. A striking feature of the PLE-like element in these genes is its location 10-33 bp upstream of the translation stop codon. We demonstrate that HIV-EP2 mRNA has a <20-nt poly(A) tail, for which the identified PLE-like sequence is responsible. These results indicate that the presence of a PLE can predict mRNAs with <20-nt poly(A) tails, and that nuclear regulation of poly(A) tail length is a feature of many mRNAs.

Animals↗

PubMed1999

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians.

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

Alleles↗

PubMed1999

Targeted disruption of SMAD3 results in impaired mucosal immunity and diminished T cell responsiveness to TGF-beta.

SMAD3 is one of the intracellular mediators that transduces signals from transforming growth factor-beta (TGF-beta) and activin receptors. We show that SMAD3 mutant mice generated by gene targeting die between 1 and 8 months due to a primary defect in immune function. Symptomatic mice exhibit thymic involution, enlarged lymph nodes, and formation of bacterial abscesses adjacent to mucosal surfaces. Mutant T cells exhibit an activated phenotype in vivo, and are not inhibited by TGF-beta1 in vitro. Mutant neutrophils are also impaired in their chemotactic response toward TGF-beta. Chronic intestinal inflammation is infrequently associated with colonic adenocarcinoma in mice older than 6 months of age. These data suggest that SMAD3 has an important role in TGF-beta-mediated regulation of T cell activation and mucosal immunity, and that the loss of these functions is responsible for chronic infection and the lethality of Smad3-null mice.

Animals↗

PubMed1999

The refolding, purification, and activity analysis of a rice Bowman-Birk inhibitor expressed in Escherichia coli.

A putative rice trypsin/chymotrypsin inhibitor of the Bowman-Birk family, RBBI-8 of about 20 kDa, was expressed in Escherichia coli as a fusion protein bearing an N-terminal (His)6 purification tag. The expressed recombinant protein, rRBBI-8, is insoluble and accumulates as inclusion bodies. The insoluble protein was solubilized in 8 M urea under reducing environment and then refolded into its active conformation under optimized redox conditions. Strategies used to optimize yield and efficiency include selecting the redox system, increasing protein concentration during refolding by adding the denatured protein in a stepwise way, utilizing additives to prevent aggregation, and selecting buffer-exchanging conditions. A Ni-chelate affinity column was then employed to purify the renatured protein. rRBBI-8 shows strong inhibitory activity against trypsin and it can slightly inhibit chymotrypsin. In this study, a refolding and purification system was set up for this cysteine-rich recombinant protein expressed in a prokaryotic system.

Amino Acid Sequence↗

PubMed1999

Identification of highly methylated arginine residues in an endogenous 20-kDa polypeptide in cancer cells.

Enzymatic methylation of endogenous proteins in several cancer cell lines was investigated to understand a possible relationship between protein-arginine methylation and cellular proliferation. Cytosolic extracts prepared from several cancer cells (HeLa, HCT-48, A549, and HepG2) and incubated with S-adenosyl-L-[methyl-3H]methionine revealed an intensely [methyl-3H]-labeled 20-kDa polypeptide. On the other hand, cytosolic extracts prepared from normal colon cells did not show any methylation of the 20-kDa protein under identical conditions. To identify nature of the 20-kDa polypeptide, purified histones were methylated with HCT-48 cytosolic extracts and analyzed by SDS-PAGE. However, none of the histones comigrated with the methylated 20-kDa polypeptide, indicating that it is unlikely to be any of the histone subclasses. The [methyl-3H]group in the 20-kDa polypeptide was stable at pH 10-11 (37 degrees C for 30 min) and methylation was not stimulated by GTPgammaS (4 mM), thus the reaction is neither carboxyl methylesterification on isoaspartyl residues, nor on C-terminal farnesylated cysteine. The present study together with the previous identification of N(G)-methylated arginine residues in the HCT-48 cytosol fraction suggests that this novel endogenous 20-kDa arginine-methylation is a cellular proliferation-related posttranslational modification reaction.

Animals↗

PubMed1999

A methodology for partitioning a vocabulary hierarchy into trees.

Controlled medical vocabularies are useful in application areas such as medical information systems and decision-support systems. However, such vocabularies are large and complex, and working with them can be daunting. It is important to provide a means for orienting vocabulary designers and users to the vocabulary's contents. We describe a methodology for partitioning a vocabulary based on an IS-A hierarchy into small meaningful pieces. The methodology uses our disciplined modeling framework to refine the IS-A hierarchy according to prescribed rules in a process carried out by a user in conjunction with the computer. The partitioning of the hierarchy implies a partitioning of the vocabulary. We demonstrate the methodology with respect to a complex sample of the MED, an existing medical vocabulary.

Models, Theoretical↗

PubMed1999

Pancreas dorsal lobe agenesis and abnormal islets of Langerhans in Hlxb9-deficient mice.

In most mammals the pancreas develops from the foregut endoderm as ventral and dorsal buds. These buds fuse and develop into a complex organ composed of endocrine, exocrine and ductal components. This developmental process depends upon an integrated network of transcription factors. Gene targeting experiments have revealed critical roles for Pdx1, Isl1, Pax4, Pax6 and Nkx2-2 (refs 3,4,5,6,7, 8,9,10). The homeobox gene HLXB9 (encoding HB9) is prominently expressed in adult human pancreas, although its role in pancreas development and function is unknown. To facilitate its study, we isolated the mouse HLXB9 orthologue, Hlxb9. During mouse development, the dorsal and ventral pancreatic buds and mature beta-cells in the islets of Langerhans express Hlxb9. In mice homologous for a null mutation of Hlxb9, the dorsal lobe of the pancreas fails to develop. The remnant Hlxb9-/- pancreas has small islets of Langerhans with reduced numbers of insulin-producing beta-cells. Hlxb9-/- beta-cells express low levels of the glucose transporter Glut2 and homeodomain factor Nkx 6-1. Thus, Hlxb9 is key to normal pancreas development and function.

Animals↗

PubMed1999

Robustness of protein folding kinetics to surface hydrophobic substitutions.

We use both combinatorial and site-directed mutagenesis to explore the consequences of surface hydrophobic substitutions for the folding of two small single domain proteins, the src SH3 domain, and the IgG binding domain of Peptostreptococcal protein L. We find that in almost every case, destabilizing surface hydrophobic substitutions have much larger effects on the rate of unfolding than on the rate of folding, suggesting that nonnative hydrophobic interactions do not significantly interfere with the rate of core assembly.

Amino Acid Substitution↗