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Biomedical subjects

S Du

Publications and source records attributed to S Du.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Studies on multiple infection with hepatitis B, C and G viruses].

OBJECTIVE: To study if there exists superinfection and multiple infection in the patients with hepatitis G virus (HCV) infection. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) technique in non-structural gene 3 (NS3) region of HGV was used to detect HGV RNA in serially diluted quality control sera and HGV-C reference panel of samples provided by Abbott Co. Ltd, in 90 cases with positive hepatitis C virus (HCV) RNA, and 12 blood donors with super-infection of hepatitis B virus (HBV) and hepatitis C virus (HCV). RESULTS: Serially diluted quality control sera showed positive for HGV RNA at dilutions of 10(-1) to 10(-5), but negative at dilutions of 10(-6) to 10(-8). HGV RNA was positive in two samples of HGV-C serum provided by Abbott Co. HGV RNA was positive in eight of the 90 cases with positive HCV RNA and in four of the 12 cases with super-infection with HCV and HBV. CONCLUSION: There are not only super-infection of HBV and HCV, but also multiple infection.

Flaviviridae↗
PubMed1998

[An experimental study on mechanism of intraocular pressure decline after allogeneic transplantation of trabecular meshwork].

OBJECTIVE: To study the mechanism of intraocular pressure (IOP) decline after allogeneic transplantation of trabecular meshwork (TM) in primate experimental glaucoma. METHODS: The experimental open-angle glaucoma models were created in 8 rhesus monkey eyes by repeated pangoniophotocoagulation on functional TM using argon laser. After 2, 3, 5 months respectively, avidin-gold or self-erythrocytes, which acted as tracers of the aqueous humor outflow, were perfused into the anterior chamber under normal pressure and volume conditions. 30 minutes later, 2.5% glutaraldehyde was perfused into the anterior chamber under the same conditions. Allograft TMs and photocoagulated area (serving as the control) were observed by light, transmission, scanning electron microscopy and ultrahistochemistry study. RESULTS: The IOP of 5 eyes of 6 experimental eyes became normal. A blood reflux into Schlemm's canal was seen by gonioscopy in 4 eyes. The surface of TMs from graft showed the normal uveal TM cords and intertrabecular spaces. Erythrocytes were found in the intertrabecular spaces and Schlemm's canal. Avidin-gold and vacuolar containing gold were observed in the cells of TM and Schlemm's canal. The TMs of photocoagulated area appeared to be fewer and narrower intertrabecular spaces. The uveal cords of this zone were confused. The content of acid mucopolysaccharides in the grafts was closer to normal than that in the photocoagulated areas. CONCLUSION: TM of allogeneic transplantation not only can survive but also function as an aqueous humor outflow pathway. We consider that this operative procedure can be used for treatment of some cases with glaucoma cautiously.

Animals↗
PubMed1997

[Relationship between dietary nutrients intakes and human prostate cancer].

In order to study the relationship between dietary nutrients intakes and prostate cancer, 1 : 1 matched case-control study was carried out with 102 patients suffered from histologically confirmed prostate cancer and 102 healthy controls. Total calories and 11 nutrients including protein, lipid and carbohydrates were calculated based on the mean food intakes in the latest 3 days. Analyzed by matched t-test and conditional logistic regression method, the results showed that high intakes of lipid, carbohydrates, and retinol increased the risk of prostate cancer, but vitamin C and vitamin B1 decreased the risk of prostate cancer. The multivariable adjusted ORs were 1.65 (95% confident interval (CI) 1.39-1.96) for lipid, 1.22 (95% CI 1.13-1.31) for carbohydrates, 3.21 (95% CI 2.18-4.75) for retinol, 0.61 (95% CI 0.6-0.80) for vitamin C, and 0.029 (95% CI 0.009-0.09) for vitamin B1. The authors discussed the possible mechanism of dietary nutrients contributing to the risk of prostate cancer.

Adult↗
PubMed1997

[Epidemiological study on human prostate cancer in Wuhan City].

In America, Canada and many European countries, prostate cancer is the most common cancer and the second leading cause of cancer death in men. In China, the morbidity rate and mortality rate of prostate cancer are unknown. Based on the reports of Wuhan cancer surveillance in 1990-1992, this study researched the epidemiological characterics of prostate cancer. The results showed that morbidity rate and mortality rate in Wuhan city are 1.37 and 0.75 per 100,000 respectively, and the standardized morbidity rate and standardized mortality rate are 1.10 and 0.66 per 100,000 respectively. They also showed that history of urinary diseases (OR = 5.42, 95% confidence interval (CI): 1.56-18.83), children number with more than 3 (OR = 2.43, 95% CI: 1.17-5.02), coitus with more than 3 times per week in youth (OR = 3.38, 95% CI: 1.51-7.58), frequent use of sexual drugs (OR = 4.12, 95% CI: 1.65-10.25) and high body mass index (OR = 2.58; 95% CI: 1.30-5.11) are identified as risk factors of prostate cancer statistically, but physical labor (OR = 0.35, 95% CI: 0.17-0.71) and age of first nocturnal emission after 18 years old (OR = 0.20, 95% CI: 0.08-0.52) are protective factors.

Adult↗
PubMed1997

[Sequence analysis of 5' non-coding region of hepatitis G viruses and preliminary classification of genotypes].

For analyzing the structural characteristics of hepatitis G virus (HGV or GBV-C), 277 nucleic acids of 5' non-coding region of HGV were amplified using PCR from the sera of 2 paid donors, 2 chronic hepatitis patients and 2 patients with liver cirrohsis. The products were cloned and sequenced. The data were analyzed with the computer programs. The results indicated that the gene sequence homologies among 6 HGV isolates (G001-G006) obtained in this study were above 96.2%. The comparison of these 6 isolates and 3 foreign isolates reported previously showed that the sequence homologies were in the range from 86.9% to 91.6%. According to the variability of gene sequences, the preliminary division of genotypes of 6 Chinese HGV isolates (G001-G006) and 3 isolates reported abroad were classified into three distinct groups. The results suggest that the gene sequences of Chinese HGV isolates are highly homologous but have an obvious divergence with the foreign isolates. The 5' untranslated regions of all isolates analyzed probably contain a stable and similar secondary structure.

5' Untranslated Regions↗
PubMed1997

[Variation in hepatitis C virus NS 5b nucleotide sequence and its relationship with interferon treatment].

In order to investigate variation in hepatitis C virus (HCV) nonstructural 5b (NS5b) nucleotide sequence and the relationship with interferon treatment, cDNA containing in this region were obtained by reverse transcription-polymerase chain reaction from the sera of 4 HCV RNA positive asymptomatic chronic carriers and 9 chronic hepatitis C patients. The cDNA were then directly analysed by polymerase-chain-reaction-directed sequencing. Compared with three published HCV type II/1b sequences (HCV-J, HC-C2 and HCV-BDS), the homology of HCV was lower in the patients with chronic hepatitis C (93.52% +/- 2.09% average), especially in nonresponders to interferon (92.70 +/- 1.90% average), than in asymptomatic HCV carriers (95.65 +/- 2.61%). In 5 patients, HCV RNA was eliminated by interferon treatment. In the remaining 4 interferon-treated HCV survived patients there were 9-48 nucleotide substitutions in HCV mutants out of 380 nucleotides, resulting 6-20 amino acids changes out of 126 amino acids. These results suggested that NS5b region variants play an important role in maintaining persistent infection and the evolution of NS5b is associated with the effect of interferon treatment.

Adult↗
PubMed1996

Vaccinia virus DNA replication: two hundred base pairs of telomeric sequence confer optimal replication efficiency on minichromosome templates.

Vaccinia virus is a complex DNA virus that exhibits significant genetic and physical autonomy from the host cell. Most if not all of the functions involved in replication and transcription of the 192-kb genome are virally encoded. Although significant progress has been made in identifying trans-acting factors involved in DNA synthesis, the mechanism of genome replication has remained poorly understood. The genome is a linear duplex with covalently closed hairpin termini, and it has been presumed that sequences and/or structures within these termini are important for the initiation of genome replication. In this report we describe the construction of minichromosomes containing a central plasmid insert flanked by hairpin termini derived from the viral genome and their use as replication templates. When replication of these minichromosomes was compared with a control substrate containing synthetic hairpin termini, specificity for viral telomeres was apparent. Inclusion of > or = 200 bp from the viral telomere was sufficient to confer optimal replication efficiency, whereas 65-bp telomeres were not effective. Chimeric 200-bp telomeres containing the 65-bp terminal element and 135 bp of ectopic sequence also failed to confer efficient replication, providing additional evidence that telomere function is sequence-specific. Replication of these exogenous templates was dependent upon the viral replication machinery, was temporally coincident with viral replication, and generated covalently closed minichromosome products. These data provide compelling evidence for specificity in template recognition and utilization in vaccinia virus-infected cells.

Animals↗
PubMed1996

PO149, a new member of pollen pectate lyase-like gene family from alfalfa.

PO149 is a low-copy-number gene expressed in the late stages of pollen development. The promoter region contains no similarities in DNA sequence to those of other pollen-specific genes, except for a tobacco sequence (AAATGA), which occurs four times in this alfalfa gene and much further upstream than in tobacco. Four distinct TATA boxes were detected in the promoter with the distal and proximal TATA boxes being separated by a spacer of 269 nucleotides. Hairpin loop structures were found in the 5'- and 3'-untranslated regions of PO149 mRNA. The coding region of PO149 is interrupted by two introns and encodes a putative prepeptide of 450 amino acids with homology to pollen pectate lyase-like proteins and pollen allergens. The coding region also contains sequences characteristic of both a signal peptide and a nuclear localization signal.

Allergens↗
PubMed1996

Cloning and characterization of PO22, a pollen-expressed gene in alfalfa.

Genomic and cDNA clones have been isolated for a new gene (PO22) expressed in mature pollen of alfalfa. PO22 represents a single- or low-copy gene containing 4 introns, 2 transcriptional start sites, and coding for a predicted protein of 340 amino acids with no signal peptide and a coiled coil structure of 39 amino acids near the carboxyl end. The amino acid sequence of PO22 is 38% identical to that of an early nodule-specific gene (ENOD8), also from alfalfa.

Cloning, Molecular↗
PubMed1996

A moderately repetitive DNA sequence in alfalfa is transcribed in a floral-specific manner.

Based on DNA sequence analysis of 5 clones of repetitive DNA from alfalfa (Medicago sativa), we propose the existence of a dispersed middle repetitive element about 3400 bp long with a copy number in the range of 2-3 x 10(3) per haploid genome. The average A+T content of the sequences was 54.6%, compared with 61.4% for the alfalfa genome. Sequence homologies between overlapping regions of the clones ranged from 85 to 89.5% with an average of 86.6%; sequence divergence was due largely to single base pair changes, with deletions or insertions occurring randomly across sequences. An open reading frame (ORF) in one clone, RPE15, contained homologies to cereal prolamin genes and a legumin box was located upstream of the coding region. A Northern blot of RNA from various alfalfa tissues, probed with the above clone containing this ORF, showed an extensive heterodispersed pattern of hybridization in the late stages of flower bud development but in no other tissues.

Base Composition↗
PubMed1996

[Detection of hepatitis C virus RNA in paraffin embedded liver tissues by in situ PCR].

The new technique of in situ polymerase chain reaction (ISPCR) was used to study hepatitis C virus (HCV). ISPCR and in situ hybridization (ISH) were performed to detect HCV in 7 paraffin embedded liver tissues and 8 para-hepatocellular cancer tissues. The positive rates were 6/7 and 4/8 respectively, significantly higher than results obtained by ISH, which were 3/7 and 1/8 respectively. It also demonstrated that the specificity of ISPCR was better than ISH. HCV RNA was not only found in hepatocyte plasma but also in cholangiolar epithelia and monocytes. We conclude that ISPCR is a sensitive and specific method that can improve the accuracy in diagnosis of HCV.

Base Sequence↗
PubMed1996

[Establishment of labeled primer reverse transcription in situ polymerase chain reaction and detection of hepatitis C virus in liver tissues].

OBJECTIVES: To establish bio-11-photosoralen (BP) labeled primer reverse transcription in situ polymerase chain reaction (RT-in situ PCR), and detect the location and distribution of hepatitis C virus in 17 cases liver tissue embedded by paraffin. METHODS: The method was compared with indirect RT-in situ PCR and in situ hybridization for detecting hepatitis C virus (HCV) RNA. RESULTS: The results of serum HCV PCR and southern blot showed that BP labeled primer PCR not only is possible, but also has a good specialty. The HCV positive rate was 59% (10/17) by indirect RT-in situ PCR, 53% (9/17) positive specimens were found by BP labeled primer RT-in situ PCR. Statistical analysis revealed that chi 2 volume was 0.12, P > 0.05, the two methods had no dominantl differences. Meanwhile only 24% (4/17) positive signals were seen by in situ hybridization, which was lower than two RT-in situ PCR, chi 2 volume was 3.97 and 4.37 respectively, P < 0.05. Moreover, HCV was mainly located in hepato-plasmas, but positive signals were found in monocytes and cholangiolar epithelia. CONCLUSIONS: We conclude that both indirect RT-in situ PCR and BP labeled RT-in situ PCR have the good sensitivities and specialties for detecting HCV RNA of liver tissues, and HCV RNA locates not only in hepatocytes, but also in monocytes and cholangiolar epithelia. The results suggested that hepatocytes may be not only replicate location of hepatitis C virus.

Hepacivirus↗
PubMed1996

[Nested polymerase chain reaction (PCR) and multiple cloned antibody capture PCR for the examination of serum hepatitis B virus DNA in negative hepatitis B surface antigen patients suffering from liver diseases].

In order to find out rapidly the causes of the liver diseases suffered by patients with negative hepatitis B surface antigen (HBsAg), nested polymerase chain reaction (PCR) and multiple cloned antibody capture PCR techniques were established to examine serum hepatitis B virus (HBV) DNA. By using both techniques along with the examination of hepatitis C virus (HCV) infection, the causes of chronic liver diseases with negative HBsAg were studied. It is found that nested-PCR can increase the sensitivity of single PCR more than 1,000 fold and multiple cloned antibody capture-PCR can detect concentration of HBV DNA as low as 0.1-0.01 pg/L. HBV DNA positive patients were found in 45.5%, 30.8%, 13.3% and 100% respectively of the patients suffering from liver cirhosis with negative HBsAg (group A, 22 cases), chronic hepatitis with negative HBsAg (group B, 13 cases), normal subjects with negative HBsAg and positive hepatitis B core antibody (HBcAb, group C, 30 cases) and liver cirhosis with positive HBsAg and negative HBeAg (group D, 12 cases). HBV DNA can be also found in the serum of HBsAb positive patients and subjects supposed to be healthy, 81.8% and 53.8% of the patients were infected with HBV and/or HCV in group A and group B respectively. All these results suggest that nested-PCR and multiple cloned antibody capture-PCR are rapid and highly sensitive methods for detection of serum HBV DNA. HBV infection is an important cause of chronic liver diseases in patients with negative HBsAg. The causes of most of the HBsAg-negative chronic liver diseases are related with infection of viruses. The clinical significance of serum HBsAb in naturally infected patients should be reconsidered.

Adult↗
PubMed1994

[Epidemiologic study on the risk factors of postpartum hemorrhage].

The 1:2 matched case-control retrospective study of postpartum hemorrhage (PPH) was undertaken in Suizhou, Hubei Province from 1 January 1990 to 31 December 1991. The subjects consisted of 109 women who had a PPH (blood loss equal to or more than 500 ml) and 218 women whose blood loss at delivery was less than 200 ml. The results showed that multiparity, age younger than 20 or older than 36, long second and third stages of labour, abortion, low income, lack of obstetric care, etc, were identified as risk factors statistically.

Adult↗
PubMed1993

Metal ion binding to dog osteocalcin studied by 1H NMR spectroscopy.

One-dimensional 1H NMR was employed to study the effects of Ca2+ and Lu3+ binding on the apo and calcium-saturated forms of dog bone Gla protein (BGP, osteocalcin). Titration of apo dog BGP with Ca2+ in 20 mM NaCl showed spectral perturbations consistent with the binding of 5 mol equiv of calcium in the NMR slow-exchange limit. The first 2 Ca2+ equiv induced significant conformational changes in the apoprotein, binding cooperatively with a Kd1 approximately 5.0 x 10(-4) M and a Hill coefficient H = 2.3 in 20 mM NaCl. The last 3 equiv bound with a slightly weaker affinity and did not induce significant structural changes. Neither the affinity nor the stoichiometry of calcium binding was significantly altered at 150 mM NaCl. The addition of only 1 Lu3+ equiv to apo dog osteocalcin was sufficient to induce the same spectral perturbations as 2 Ca2+ ions. The addition of 2 Lu3+ equiv to calcium-saturated osteocalcin had little effect on its 1H NMR spectrum, and BGP aggregated at [Lu3+]o/[BGP]o ratios greater than 2 in either the presence or absence of calcium. The spectrum of calcium-saturated osteocalcin was invariant at < or = 55 degrees C (< or = 50 degrees C in 150 mM NaCl), after which the proton resonances shifted to frequencies more characteristic of apo BGP. Saturation with calcium somewhat stabilized the apo dog osteocalcin protein against conformational changes induced at pH extremes; apo BGP was stable at 6.0 < or = pH < or = 10, and calcium-saturated BGP was stable at 5.8 < or = pH < or = 10. Both our NMR and gel filtration data indicate that calcium-saturated osteocalcin exists as a dimer at both high and low protein concentrations. A conformational change in dog osteocalcin was thus induced by the cooperative association of Ca2+ to two high-affinity sites on the protein and stabilized by the association of 3 additional Ca2+ equiv. The results of our temperature and calcium binding studies were consistent with an estimated Kd1 approximately 5.0 x 10(-4) M for the two high-affinity sites. Lutetium induced the same structural changes in osteocalcin as calcium, but the two high-affinity Ca2+ binding sites did not have equal affinities for Lu3+. The BGP:Ca2+ complex was unstable at the low pH conditions induced by osteoclasts during bone resorption, yet the osteocalcin protein retained a BGP:Ca(2+)-like conformation at low pH. However, unlike the calcium-saturated form of the protein, osteocalcin was monomeric at low pH.

Amino Acid Sequence↗
PubMed1991

[Chemical constituents of Alyxia levinei Merr].

Three compounds were isolated from the stem and leaves of Alyxia levinei. On the basis of spectrometric analysis and physico-chemical constants they were identified as oleanolic acid, betulin and beta-sitosterol-D-glucoside respectively.

Antineoplastic Agents, Phytogenic↗