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Biomedical subjects

N Zhu

Publications and source records attributed to N Zhu.

At least 73 records · Page 4Linked to original sources
PubMed1996

Homotypic interaction and multimerization of hepatitis C virus core protein.

Hepatitis C virus (HCV) core protein constitutes a viral nucleocapsid and may possess multiple functions. In this study, we demonstrated the homotypic interaction and multimerization of HCV core protein in vitro and in vivo. By using a yeast two-hybrid system, we showed that the amino-terminal hydrophilic portion (amino acids 1-115) of the core protein could interact with itself. Deletion analysis mapped the interacting domain within amino acid residues 36-91. The homotypic interaction of the core protein was also confirmed by in vitro protein-protein blotting assay using the recombinant HCV core proteins and by its binding to the glutathione S-transferase core fusion protein. The biological significance of the core protein self-interactions was demonstrated by the detection of multimeric forms of the core protein in mammalian cells. The domain responsible for multimerization was determined to be within the amino-terminal hydrophilic region (amino acids 1-115). Both the membrane-bound and the free core proteins exist in dimeric and multimeric forms, suggesting that multimerization of the HCV core protein occurred at an early stage of viral assembly and that the multimer forms may be involved in multiple functions of the core protein.

Animals↗
PubMed1996

[Evaluation of levator palpebrae superioris muscle resection in 500 cases].

We sum up the effects of levator palpebrae superioris muscle resection to correct congenital ptosis in 500 cases. The surgical results in 369 cases (73.8%) are excellent; ninety-six cases (19.2%) are good and 35 cases (7%) are poor. The operative result depends on the amount of muscle resection. We believe that the levator palpebrae superioris muscle resection is the first choice of treatment for a patient whose levator has no function. The operation method is described and the indications of the operation and related problems are discussed.

Blepharoptosis↗
PubMed1996

Community-based health insurance in China: bending to the wind of change.

China's Cooperative Medical System, a community-based health insurance scheme, declined markedly after the economic restructuring of rural communities and the development of a private market in the health sector during the late 1970s. However, a study of the modified system in Taichang County, where it remains popular, has revealed that insurance premiums (calculated as a percentage of household income), copayments, the inclusion of non-agricultural workers, and strong political support not only favoured the system but also increased its efficiency and effectiveness.

China↗
PubMed1996

[Middle ear function in children with cleft palate].

Middle ear problems in patients with cleft palate have for a long time received insufficient attention. The present study was designed to evaluate middle ear function in 56 children with cleft palate and in a control group of 50 children without cleft palate. The age ranging between 5 and 14 years was similar in both groups. All children underwent routine otoscopic examinations of ear, nose and throat, and were also examined using the Madsen acoustic impedance audiometer. Four major parameters (static compliance, middle ear pressure, acoustic stapedius reflex and Eustachian tube function) were analyzed. It was found that the negative middle ear pressures were higher and the static compliance, which reflected the elasticity of the conducting mechanism of the middle ear, was poorer in children with cleft palate than in the controls. The proportion of children with cleft palate who showed the presence of the acoustic stapedius reflex was also lower than in the control children. Children with cleft palate have a limited ability to actively open the Eustachian tube by swallowing, as evidenced by a poor ability to equilibrate applied positive or negative middle ear pressure. A multidisciplinary approach should be adopted for the complete overall rehabilitation of children with cleft palate. Plastic surgeons to whom most of the treatment is entrusted should be concerned not only with achieving palatal function and acceptable speech, but also with the various other problems associated with cleft palate, especially those affecting the middle ear.

Abnormalities, Multiple↗
PubMed1995

Synthesis and antimicrobial activity of 6,7-annulated pyrido[2,3-d]pyrimidines.

Four new 6H-indeno[2',1':5,6]pyrido[2,3-d]pryimidines (10-13) were synthesized via cyclocondensation reactions involving chlorovinyl aldehyde 1 or ketoaldehyde 3 and appropriately substituted 6-aminopyrimidines. The regiochemistry of the compounds was established by 1H NMR and 13C NMR spectral data as well as X-ray crystal data. Compounds 10 and 11 and previously reported homologues 14 and 15 were screened for antimicrobial activity. Moderate antimicrobial activity was observed for some of these compounds. Compound 14 was especially active against Staphylococcus aureus. Crystal data for 13 (C14H7N3Cl2) follows: monoclinic space group, P21/n; Unit cell dimensions, a = 7.284(1) A, b = 12.800(1) A, c = 13.108(1) A, beta = 93.98(1) degree, V = 1219.2(2) A3, Z = 4.

Anti-Bacterial Agents↗
PubMed1995

Myocardial venous O2 saturation becomes more heterogeneous during hypoxic and carbon monoxide hypoxia.

The hypothesis tested was that myocardial venous O2 saturation (SvO2) heterogeneity, a measure of microregional O2 supply/consumption balance, would increase under hypoxic and CO-hypoxia conditions. Since we are able to determine both O2 supply and the O2 supply/consumption ratio, we could also determine whether regional myocardial O2 consumption was heterogeneous. Twenty open-chest anesthetized dogs were studied under control and four hypoxic conditions, hypoxic hypoxia induced by ventilation with either an 8% O2 (SaO2 = 56%) or a 6% O2 (SaO2 = 40%) gas mixture for 20 min, or CO hypoxia induced by ventilation with a 1% CO gas mixture for either 7 min (SaO2 = 67%) or 20 min (SaO2 = 40%). Regional myocardial blood flow was measured using radioactive microspheres in 40 pieces (approximately 0.5 g) of the left ventricular free wall. Arterial and venous O2 saturations were determined with a four-wavelength microspectrophotometric method. A total of 28 veins (20-100 microns) were examined to determine SvO2 for each condition within each animal. The coefficient of variation (CV = SD/mean x 100), an index of heterogeneity, was calculated for both flow and SvO2 under each condition. Flow increased with increasing severity of hypoxia but its heterogeneity did not change with hypoxic or CO hypoxia. However, SvO2 heterogeneity significantly increased with increasing severity of hypoxia. A linear regression of SvO2 CV and mean SvO2 showed a significant correlation (CV = -0.84 (mean SvO2) + 51.1, R = 0.59). All possible myocardial O2 consumptions were calculated by multiplying all of the flows and O2 extractions. In 53 subepicardial and subendocardial measurements, only 10% of the flow and O2 supply/consumption heterogeneity observations could be explained by uniform O2 consumption if our acceptance criterion was 0.06-0.1 ml O2/min/100 g, and 50% could be explained with an acceptance criterion of 0.3-0.4 ml O2/min/100 g. Therefore, there must be some regional myocardial O2 consumption heterogeneity. The increase in venous O2 saturation heterogeneity during hypoxia may be due to increased variation in regional myocardial O2 consumption or variation in the control of O2 supply/consumption coupling.

Animals↗
PubMed1995

Old-age support system and policy reform in China.

"With the on-going economic transition from the central planned system to a market-oriented system, the population aging process in China is also accelerating, and the support system for the elderly becomes an important issue demanding attention. With data from Chinese national statistics and a regional probability sampling survey in Wuhan Area, two supporting systems for the aged in China are examined in this paper. After a briefing of the population aging process in China, a detailed discussion of the two supporting systems, i.e. the formal and the informal support systems for the aged, including arrangement, operation and funding mechanisms of the systems, is made in terms of policy reform. Then follows an international comparison to highlight features and problems of the Chinese systems. Finally, solutions are proposed for the restructuring of China's pension systems."

Age Distribution↗
PubMed1995

[Detection of FMR-1 gene expression by RT-PCR].

Fragile X syndrome [FRA(X)] as the most common form of inherited mental retardation in man has an incidence of one per 1250 and is associated with a fragile site at Xq27.3. A gene was identified at the fragile X locus and was designated Fragile X Mental Retardation-1 (FMR-1). FRA(X) resulted from expansion of (CGG)n trinucleotide repeat in 5' untranslated region of the human FMR-1 gene, and was associated with abnormal methylation of a CpG island 250 bp proximal to this (CGG)n repeat. Males with typical FRA(X) showed repression of FMR-1 transcription and absence of FMR-1 protein, which was believed to contribute to the fragile X phenotype. FMR-1 mRNA extracted from leukocytes in normal and clinically suspected males were detected by RT-PCR. The methylation status and CGG expansion were also studied by PCR and Southern blot. Two of 10 clinically suspected males were found devoid of FMR-1 expression and accompanied with hypermethylation of the CpG island and CGG trinucleotide repeat expansion.

CpG Islands↗
PubMed1994

(-)-Norcocaine.

The title compound, [2R,3S-(2 beta,3 beta)]-methyl 3-(benzoyloxy)-8-azabicyclo[3.2.1]octane-2-carboxylate, C16H19NO4, is a metabolite of the tropane alkaloid cocaine. The molecule crystallized as the free base with the piperidine ring in a chair conformation. The tropane ring system and its methoxycarbonyl and benzoyl groups are rigid; only rotational flexibility is allowed in the conformation of the substituents.

Cocaine↗
PubMed1994

The lipids of slugs and snails: evolution, diet and biosynthesis.

There is a considerable gap in current knowledge of the lipid composition of snails and slugs, both of which belong to the phylum Mollusca. We have therefore analyzed the sterol and fatty acid compositions of three species of slugs and three species of snails. The sterols of slugs included eight different sterols: cholesterol contributed 76-85% of the total sterols, brassicasterol accounted for 4-13%; other sterols we identified were lathosterol, 24-methylene cholesterol, campesterol, stigmasterol, sitosterol and sitostanol. In contrast, snails contained two additional sterols, desmosterol and cholestanol. Of the polyunsaturated fatty acids in slugs, linoleic (18:2n-6) and arachidonic acids (20:4n-6) were the major n-6 fatty acids, while linoleic (18:3n-3) and eicosapentaenoic acids (20:5n-3) were the predominant n-3 fatty acids. Docosahexaenoic acid (22:6n-3), the end product in the n-3 fatty acid synthetic pathway and an important membrane fatty acid of mammals, fish and birds, was absent in both slugs and snails. However, the analogous product of n-6 fatty acid synthesis, 22:5n-6, was found in both snails and slugs. This raises speculation about preference for n-6 fatty acid synthesis in these species. Our data show the unique sterol and fatty acid compositions of slugs and snails, as well as similarities and differences in sterol composition between the two. The results between the two land mollusks are contrasted with those of marine mollusks, such as oysters, clams and scallops.

Animals↗
PubMed1994

Effect of hypoxic and carbon monoxide-induced hypoxia on regional myocardial segment work and O2 consumption.

The purpose of this study was to investigate the potentially greater responses of regional myocardial work and O2 consumption to hypoxic hypoxia than to CO-induced hypoxia. Twenty open-chest anesthetized dogs were studied under control and four hypoxic conditions, hypoxic hypoxia induced with either 8% O2 (SaO2 = 56%) or 6% O2 (SaO2 = 40%) gas mixtures, or CO-induced hypoxia produced by a 1% CO gas mixture for either 7 min (SaO2 = 67%; SaCO = 30%) or 20 min (SaO2 = 40%; SaCO = 56%). Ultrasonic crystals and a force gauge were utilized to measure myocardial shortening and force. Regional myocardial segment work was calculated by integrating myocardial segment shortening multiplied by its corresponding force. Radioactive microspheres were used to measure regional coronary blood flow during each condition. Transmural biopsies were utilized to measure arterial and venous O2 saturation with a four-wavelength microspectrophotometric method. Regional O2 extraction and consumption were calculated. Regional coronary blood flow (77 +/- 38 ml/min per 100 g, control) increased with severe hypoxic hypoxia (293 +/- 206) and CO-induced hypoxia (150 +/- 128). Regional myocardial O2 extraction was decreased with both hypoxic and CO hypoxia. Regional myocardial O2 consumption was maintained even with severe hypoxic and CO hypoxia. Regional myocardial segment work/min increased from 343 +/- 205 g* mm/min with increasing levels of hypoxic hypoxia (564 +/- 677) and decreased with increasing levels of CO hypoxia (169 +/- 111). Regional segment work increased with increasing levels of hypoxic hypoxia and decreased with increasing CO hypoxia. The differential effects on segment work caused by the two types of hypoxia may be due to direct metabolic or autonomic differences.

Animals↗
PubMed1994

Prenatal ethanol exposure reduces phosphoinositide hydrolysis stimulated by quisqualate in rat cerebellar granule cell cultures.

Prenatal ethanol exposure-induced alteration in poly-phosphoinositide (PPI) hydrolysis stimulated by excitatory amino acids (EAA) was studied in rat cerebellar granule cells previously labeled with [3H]myoinositol. The prenatal exposure to ethanol was achieved via maternal consumption of a Sustacal (chocolate flavored) liquid diet containing either 5% ethanol (w/v, 35% of calories) or isocaloric sucrose (pair-fed) substituted for ethanol from gestation d 11 until the day of parturition. The ionotropic glutamate receptor agonists, N-methyl-D-aspartate, kainate or (+/-)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) (100 microM each) induced a two- to four-fold increase in PPI hydrolysis over the basal level, regardless of the liquid dietary treatment. Stimulation with quisqualate (QA), an agonist activating both metabotropic and ionotropic glutamate receptors, resulted in a much stronger and dose-dependent response in PPI hydrolysis and exposure in utero to ethanol significantly reduced this response. Tetrodotoxin, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), or (+/-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) had no effect on QA-stimulated PPI hydrolysis nor on the suppression of this hydrolysis by ethanol. Exposure in utero to ethanol did not affect PPI hydrolysis stimulated by a selective metabotropic glutamate receptor agonist, trans-(+/-)-l-amino-1,3-cyclopentanedicarboxylic acid (t-ACPD). Although the PPI hydrolysis stimulated by t-ACPD could be blocked by (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG), an antagonist of the metabotropic glutamate receptor, MCPG was incapable of affecting QA-induced PPI hydrolysis and the suppressive effects of prenatal ethanol exposure on this hydrolysis. Taken together, the data suggest that the long-lasting suppressive effects of prenatal ethanol exposure on QA-stimulated PPI hydrolysis in cerebellar granule cell cultures is through a metabotropic QA receptor pathway that may be different from the one activated by t-ACPD.

Animals↗
PubMed1993

Systemic gene expression after intravenous DNA delivery into adult mice.

Direct gene transfer into adult animals resulting in generalized or tissue-specific expression would facilitate rapid analysis of transgene effects and allow precise in vivo manipulation of biologic processes at the molecular level. A single intravenous injection of expression plasmid:cationic liposome complexes into adult mice efficiently transfected virtually all tissues. In addition to vascular endothelial cells, most of the extravascular parenchymal cells present in many tissues including the lung, spleen, lymph nodes, and bone marrow expressed the transgene without any apparent treatment-related toxicity. The transgene was still expressed in large numbers of cells in multiple tissues for at least 9 weeks after a single injection. Expression could be targeted to specific tissues and cell types, depending on the promoter element used.

Animals↗
PubMed1993

Molecular analysis of HLA-DR beta and DQ beta polymorphism in Chinese with rheumatoid arthritis.

OBJECTIVES: Several studies have suggested that genetic predisposition to rheumatoid arthritis may be related to the presence of specific polymorphic HLA sequences that are often associated with HLA-DR4 haplotypes. This study was performed to determine if an association exists between Chinese with rheumatoid arthritis and a particular HLA-DR beta or DQ beta subtype. METHODS: This study used the polymerase chain reaction to amplify HLA-DR beta and DQ beta genes, and oligonucleotide probe hybridisation to examine the association of certain polymorphic sequences with rheumatoid arthritis in 23 Chinese patients from Shanghai. RESULTS: An HLA-DR4 associated sequence was significantly increased in the Chinese patients (43%) compared with healthy controls (14%) from the same location (relative risk = 4.6, 95% confidence limits 1.1 to 19.3). Analysis of the third hyperpolymorphic region of DR4 positive samples was performed to detect polymorphic sequences associated with Dw4, Dw10, Dw13, Dw14, Dw15, and KT2 cellular specificities. Examination of this region showed that 91% of patients had sequences encoding amino acids QRRAA (associated with Dw14 and Dw15) or QKRAA (associated with Dw4) compared with 64% of the DR4 positive controls. CONCLUSIONS: Rheumatoid arthritis in the Chinese is associated with HLA-DR4. There is a possible relationship between sequences within the third hyperpolymorphic region of the DRB allele and rheumatoid arthritis in the Chinese.

Amino Acid Sequence↗