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Biomedical subjects

S Du

Publications and source records attributed to S Du.

At least 37 records · Page 2Linked to original sources
PubMed2000

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

OBJECTIVE: To establish bio-11-photosoralen (BP) labeling primer reverse transcription in situ polymerase chain reaction (PCR), and to detect the location and distribution of hepatitis C virus in 30 cases liver tissues embedded with paraffin. METHODS: BPs were labeled in tymidine (T) position under ultraviolet lamp. The method was compared with indirect RT-in situ PCR and in situ hybridization for detecting hepatitis C virus (HCV) RNA. RESULTS: Serum HCV PCR and southern blot showed that BP labeling psimer PCR was possible, and had a good specificity. The HCV positive rate was 53% (16/30) by indirect in situ PCR, 50% (15/30) positive specimens were found by BP labeling primer in situ PCR. Statistical analysis revealed P > or = 0.05 and the two methods had no dominant differences. Meanwhile, only 23% (7/30) positive signals were seen by in situ hybridization, which was lower than two in situ PCR(P < or = 0.05). HCV was mainly located in hepatic-plasmas, and positive signals were found in monocytes and cholangiolar epithelia. CONCLUSIONS: Both indirect in situ PCR and BP labeling in situ PCR have good sensitivity and specificity for detecting HCV RNA of liver tissues. HCV RNA is located in hepatocytes, monocytes and cholangiolar epithelia.

Blotting, Southern↗
PubMed2000

[Measurement of human retinal thickness at posterior pole with retinal thickness analyzer in normal and glaucomatous eyes].

OBJECTIVE: To determine the diagnostic value of retinal thickness analyzer (RTA) in glaucoma. METHODS: RTA was used to measure the retinal thickness at the posterior pole in 77 normal persons (116 eyes) at various ages and 22 cases (35 eyes) with glaucoma. The obtained images were processed by a computer to yield the retinal thickness value and the thickness map at this location, and the data were analyzed with SAS software package. RESULTS: The mean retina thickness of normal subjects was (171.83 +/- 18.50) microm with no significant difference among the various age groups (F = 2.68, P > 0.05), and very significant between the sexes; the thickest retina was at the location between macula and optic nerve head, and the macular nasal retina is 11.7% thicker than its temporal side. The upper and lower retinas of the fovea were basically symmetrical. The retinal thickness in glaucoma patients showed diffuse or local thinning, and there was a very significant difference between the normal group and the glaucomatous group in retina thickness (F = 11.98, P = 0.0001). The sensitivity rate for detecting glaucoma with RTA was up to 80.8%, and specificity to 78.5%. CONCLUSIONS: The thickness map for the retina at posterior pole across the macula in normal subjects is "horse shoe" shaped, that is well matched with the topography of retinal ganglion cell and the retinal nerve fibers in human retina. Diffuse or local thinning of retinal thickness in glaucomatous patients, which is in agreement with the corresponding visual field defect, and the sensitivity of RTA is higher than that of perimeter. The RTA examination is easy to operate, has high reproducibility, no invasion, therefore it is an ideal method to measure the human retinal thickness in vivo.

Adolescent↗
PubMed2000

[Pressure influence on mRNA expression and protein synthesis of inducible nitric oxide synthetase in bovine trabecular meshwork cell].

OBJECTIVE: To investigate the inducible nitric oxide synthetase (iNOS) mRNA expression and protein synthesis in bovine trabecular meshwork cell and discuss the possible effects of nitric oxide (NO) in the development of glaucoma. METHODS: 20 mm Hg, 40 mm Hg, 60 mm Hg and 80 mm Hg pressure were respectively added on cultured trabecular cells of new born bovine. No pressure group was set as the control. The changes of iNOS mRNA and protein in trabecular meshwork cells under different pressures were demonstrated qualitatively and quantitatively by in situ hybridization and nicotinamide-adenine dinucleotide phosphate diaphorase (NADPH-d) histochemical assay. RESULTS: The expression of iNOS mRNA and its protein synthesis became higher and higher as the pressure was increased. There was weak iNOS mRNA expression in the control and 20 mm Hg groups, and no significant difference between them. 40 mm Hg and 60 mm Hg groups had a statistical difference from the control group. And 80 mm Hg group had a very significant difference from the control group. There was no difference between 40 mm Hg and 60 mm Hg groups, but they had significant difference from 80 mm Hg group. NADPH-d histochemical assay showed almost the same results except that there was significant difference between 40 mm Hg and 60 mm Hg groups. CONCLUSIONS: Pressure can evoke the expression of iNOS mRNA, and the nitric oxide thus produced can be one of the causes of trabecular meshwork destruction, that may induce or aggravate glaucoma.

Animals↗
PubMed1999

Autophosphorylation, phosphotransfer, and DNA-binding properties of the RegB/RegA two-component regulatory system in Rhodobacter capsulatus.

In the purple, photosynthetic bacterium, Rhodobacter capsulatus, the RegB/RegA two-component system is required for activation of several anaerobic processes, such as synthesis of the photosynthetic apparatus and assimilation of CO2 and N2. It is believed that RegB is an integral membrane histidine kinase that monitors the external environment. Under anaerobic growth conditions, it transduces a signal through phosphorylation of the response regulator, RegA, which then induces target gene expression. We used an in vitro assay to characterize the phosphorylation of wild-type RegA and a mutant variant (RegA*) that is responsible for abnormally high photosynthesis gene expression under both aerobic and anaerobic growth conditions. Phosphorylation assays indicate that phosphorylated RegA* (RegA* approximately P) is much more stable than RegA approximately P, indicating that it may be locked in a conformation that is resistant to dephosphorylation. DNase I footprint assays also indicate that unphosphorylated RegA* has a much higher affinity for specific DNA binding sites than the wild-type protein. Phosphorylation of RegA* increases DNA binding 2. 5-fold, whereas phosphorylation of RegA increases DNA binding more than 16-fold. Collectively, these results support the hypothesis that RegA* is a constitutively active variant that does not require phosphorylation to assume a structural conformation required to bind DNA.

Bacterial Proteins↗
PubMed1999

[Long-term follow-up of combined therapy with large-dose zinc sulfate and low-dose penicillamine in children with hepatolenticular degeneration].

OBJECTIVE: To summarize the long-term effect of combined treatment with large-dose zinc sulfate and low-dose penicillamine in children with hepatolenticular degeneration (HLD). METHODS: The patients who had symptoms were treated with large-dose zinc sulfate (100-150mg, <6yr; 150-200mg, 6-8yr; 200-300mg, 9-10yr; 300mg,>10yr; 3 times a day) in addition to low-dose penicillamine(8-10mg/kg/d) at the beginning of treatment. Zinc sulfate alone was given to the presymptomatic patients and it was used as maintenance therapy when clinical improvement was obtained. 31 children were followed up for 4-11 years. RESULTS: In 3 presymptomatic patients, no clinical abnormalities were found. Among 28 patients with symptoms, 23 patients (82%) had their symptoms and signs subsided or much improved, 2 patients(7%) remained unchanged, and 3(11%) died. Blood concentrations of copper were persistently lower than normal. Urine copper excretion of 24 hours was significantly lower than that before the combined therapy in all patients, and it became normal in 5 cases(16%) after 6 months of treatment, and in 26 cases(84%) after 1-2 years of treatment. Higher blood concentrations of zinc were found in 20 cases(65%), and higher urine zinc excretion was noted in 25 cases(81%) once or more times during the therapy. CONCLUSION: Combined therapy of large-dose zinc sulfate and low-dose penicillamine is an effective, safe and cheap treatment for children with HLD.

Adolescent↗
PubMed1999

Calcium influx and activation of calpain I mediate acute reactive gliosis in injured spinal cord.

Buffering extracellular pH at the site of a spinal cord crush-injury may stimulate axonal regeneration in rats (1; Guth et al., Exp. Neurol. 88: 44-55, 1985). We demonstrated in cultured astrocytes that acidic pH initiates a rapid increase in immunoreactivity for GFAP (GFAP-IR), a hallmark of reactive gliosis (2; Oh et al., Glia 13: 319-322, 1995). We extended these studies by investigating the effects of certain treatments on reactive gliosis developing in situ in a rat spinal cord injury model. A significant reactive gliosis was observed within 2 days of cord lesion in untreated crush or vehicle-treated, crush control animals as evidenced by increased GFAP-IR and hypertrophy of astrocytes. By contrast, infusion of Pipes buffer (pH 7.4) into the lesion site significantly reduced this increase. The increased GFAP-IR appeared to be linked to Ca2+ influx since infusion of a blocker of L-type calcium channels, nifedipine, reduced the ensuing reactive gliosis significantly. While Ca2+ modulates many signaling pathways within cells, its effect on reactive gliosis appeared to result from an activation of calpain I. Calpain inhibitor I, a selective inhibitor of mu-calpain, also significantly reduced reactive gliosis. However, calpain inhibitor II, a close structural analog which blocks m-calpain, had no salutary effect. We suggest, therefore, that the initial reactive gliosis seen in vivo may result from the activation of a neutral, Ca2+-dependent protease, calpain I, through calcium influx.

Acute Disease↗
PubMed1999

Measurement of retinal thickness in normal subjects with retinal thickness analyzer.

The retinal thickness at posterior pole of normal subjects was measured by using retinal thickness analyzer (RTA) to determine the values of retinal thickness and to establish map of retinal thickness in normal subjects. The retina of 6 mm x 6 mm in size (approximately 20 degrees, centered on the macula) at the posterior pole was scanned by using RTA to obtain images of 116 normal eyes of 77 cases of various age group. The images were processed by a computer to obtain the retinal thickness values and the thickness map of this location. The data were analyzed with SAS software package. The mean retinal thickness was 171.77 +/- 26.13 microns with no significant difference among the various age groups (P > 0.05). The thickness maps of the retina of 6 mm x 6 mm size at the posterior pole around the macula rendered a "U"-shaped pattern, extending from the disc to the superior and inferior of the fovea. The retina was found to be thin at temporal side of the fovea, with the thinnest area being at the macula central fovea. The U-shaped pattern of the retinal thickness maps was well in agreement with the topography of the ganglion cells and the retinal nerve fibers in human retina. The measurement of the retinal thickness by RTA reflected the changes in the layers of ganglion cells and the retinal nerve fiber. Each scanning session of RTA examination can yield multiple optical cross-section images of the retina and obtain retinal thickness maps of posterior pole of living eyes.

Humans↗
PubMed1999

Histological measurement of human retinal thickness.

The fresh eye balls from the accidental death adults were placed on low temperature slicer to cut into slices. The fresh sections was subjected to the direct measurement of retinal thickness by using CMIAS multi-function real color pathologic imaging analysis system. The results showed that in the total of 6 eye balls measured, the mean retinal thickness was 310.92 +/- 34.14 microns. It was concluded that it was simple and had high confidence for the fresh eye ball low temperature frozen sections to directly measure the retinal thickness, which provided a histological method for the measurement of retinal thickness and the reference of retinal thickness of Chinese adults.

Anthropometry↗
PubMed1999

In vitro activation and repression of photosynthesis gene transcription in Rhodobacter capsulatus.

It has been known for over half a century that anoxygenic photosynthetic bacteria maximally synthesize their photosystems in the absence of oxygen. During the last decade, it has become clear that this regulation is largely at the transcriptional level, with photosynthesis genes expressed only under anaerobic conditions. We describe here in vitro reconstitution of activation and repression of three photosynthesis promoters, bch (bacteriochlorophyll biosynthesis), puc (light-harvesting II apoproteins) and puf (reaction centre and light-harvesting I apoproteins) using purified transcription factors and RNA polymerase from Rhodobacter capsulatus. Previous genetic results have indicated that each of these three promoters is differentially regulated by three key regulators: CrtJ acting as a repressor of bch and puc and the two-component regulators RegA/RegB, which are activators of puc and puf. These regulators are distinct from those that mediate oxygen control in enteric bacteria. Our in vitro studies show that these purified regulators directly control the expression of the housekeeping RNA polymerase at these promoters. High-level basal expression of the bch promoter is shown to be repressed by CrtJ. The puc promoter is activated by the RegB-phosphorylated RegA protein and additionally repressed by CrtJ. At the puc promoter, CrtJ effectively competes for promoter binding with RegA, while at the bch promoter, repression appears to be by competition for the RNA polymerase binding site. In contrast to what has been suggested previously, the RegA-activated puf promoter is demonstrated as being recognized by the housekeeping RNA polymerase. We also discuss evidence that RegA approximately P activation of the puc and puf promoters involves recruitment of RNA polymerase by different modes of protein-protein interaction.

Bacterial Proteins↗
PubMed1999

Regulated expression of a highly conserved regulatory gene cluster is necessary for controlling photosynthesis gene expression in response to anaerobiosis in Rhodobacter capsulatus.

We utilized primer extension analysis to demonstrate that the divergently transcribed regB and senC-regA-hvrA transcripts contain stable 5' ends 43 nucleotides apart within the regB-senC intergenic region. DNA sequence analysis indicates that this region contains two divergent promoters with overlapping sigma70 type -35 and -10 promoter recognition sequences. In vivo analysis of expression patterns of regB::lacZ and senC-regA-hvrA::lacZ reporter gene fusions demonstrates that the regB and senC-regA-hvrA transcripts are both negatively regulated by the phosphorylated form of the global response regulator RegA. DNase I protection assays with a constitutively active variant of RegA indicate that RegA binds between regB and senC overlapping -10 and -35 promoter recognition sequences. Two mutations were also isolated in a regB-deficient background that increased expression of the senC-regA-hvrA operon 10- and 5-fold, respectively. As a consequence of increased RegA expression, these mutants exhibited elevated aerobic and anaerobic photosynthesis (puf) gene expression, even in the absence of the sensor kinase RegB. These results indicate that autoregulation by RegA is a factor contributing to the maintenance of an optimal low level of RegA expression that allows responsiveness to activation by phosphorylation.

Anaerobiosis↗
PubMed1999

Detection of GB virus C/hepatitis G virus RNA by reverse-transcription polymerase chain reaction.

Recently, a novel RNA virus, designated GB virus C or hepatitis G virus (GBV-C/HGV) has been identified which may possibly be associated with human hepatitis. In this study, the nucleotide sequences of the partial nonstructural 5 (NS5) gene of GBV-C/HGV derived from sera of eight Chinese patients were determined. The overall degree of nucleotide conservation and the existence of regional highly conserved sequences make this part of the genome suitable for the development of diagnostic reagents. On the basis of sequence analysis, two sets of oligonucleotide primers were designed to establish a nested polymerase chain reaction (PCR) for detection of GBV-C/HGV RNA. The efficacy of three PCR methods (first, one stage PCR, second, nested PCR with primers from the NS5 region designed according to the prototype sequence and the third, our newly developed PCR) was compared in 133 Chinese patients with liver disease. The positive rates of these three methods were 8.3%, 11.3% and 18.0% respectively. The specificity of our PCR detecting system was verified by sequencing and restriction fragment length polymorphism (RFLP). In conclusion, because of the heterogeneity and geographic distribution character of GBV-C/HGV, it is necessary to assess the sequence variation among Chinese patients infected with GBV-C/HGV. This may allow to identify GBV-C/HGV RNA with high sensitivity and specificity.

Base Sequence↗
PubMed1999

A clinical trial on yu cong tang in treatment of senile dementia.

Yu Cong Tang ([symbol: see text]), a TCM decoction, was used to treat senile dementia. It has the action of invigorating the spleen, reinforcing the kidney, nourishing yin, strengthening yang, improving blood circulation, dredging the channels, removing phlegm and restoring consciousness. CT, EEG, REG, Hb, PaO2, Tch, TG and 17-OHCS were tested, showing significant differences (P < 0.05 or < 0.01) before and after the treatment. Remarkable improvement was found in clinical symptoms, and the effective rate was 94.1%. Significant differences were found between the TCM and western medicine (WM) groups in symptom improvement (P < 0.05-0.01) and therapeutic results (P < 0.001).

Aged↗
PubMed1999

[A study of interferon alpha-2b as an accessory drug after glaucoma filtration surgery].

OBJECTIVE: To elucidate the inhibitory action of interferon alpha-2b (IFN alpha-2b) on the cicatrization under conjunctiva and the best way to use it after glaucoma filtration surgery. METHODS: Immunohistochemical PAP method and image biological system 2000 (IBAS 2000) were utilized to quantitatively analyze the inhibitory effect of IFN alpha-2b on the expression of epidermal growth factor receptor (EGFR) of cultured calf fibroblasts; the effects of IFN alpha-2b on collagen contents in suture-caused cicatrization under conjunctiva and changes of aqueous humor protein after trabeculectomy performed on rabbits have also been observed. RESULTS: IFN alpha-2b reduced the expression of EGFR of cultured bovine fibroblasts at a dose-dependent manner. The relationship between the EGFR and the dosage of IFN alpha-2b is Y = 2953.8 - 554.5 lgx (r = -0.98, P < 0.01). With 4.67 x 10(-5) micromol/L IFN alpha-2b not only reduced about 50% of the collagen in suture-caused cicatrization, but also significantly decreased the protein concentration of aqueous humour 3 and 72 hours after trabeculectomy. CONCLUSION: It is promising that IFN alpha-2b can be used after glaucoma filtration surgery to reduce excessive cicatrization with many advantages compared with antimetabolites.

Animals↗
PubMed1999

[Use of transcranial Doppler in monitoring cerebral blood flow velocity during peri-operation].

Transcranial Doppler was used to monitor 45 patients' middle cerebral artery blood flow velocity during anesthesia and cardiopulmonary bypass. The result was that the change in middle cerebral artery blood flow velocity was in correspondence with cerebral blood flow. This paper suggests that transcranial Doppler is a simple and practical instrument for monitoring cerebral blood flow.

Adolescent↗
PubMed1998

DNA binding characteristics of RegA. A constitutively active anaerobic activator of photosynthesis gene expression in Rhodobacter capsulatus.

In the purple non-sulfur bacterium Rhodobacter capsulatus, RegA and RegB comprise a two-component regulatory system that is required for maximal anaerobic transcription of key photosynthesis genes. RegB is a sensor kinase that uses ATP to phosphorylate its cognate response regulator, RegA. The mechanism under which RegA approximately P influences transcription of target genes has been unclear given that past attempts to demonstrate DNA binding activity by isolated RegA have failed. This led to a model invoking a role for RegA approximately P as an intermediate in a more complex multicomponent phosphoryl transfer cascade. In the present study, we describe the isolation of a mutant version of RegA (RegA*) which promotes high level expression of photosynthesis genes independent of RegB. DNase I footprint analyses show that purified RegA* binds to the promoters of the puf and puc operons at locations that are consistent with RegA functioning as a transcriptional activator for these operons. We conclude that RegA functions, like most members of the response regulator family, as a DNA-binding protein that directly affects the expression of its target genes.

Amino Acid Sequence↗
PubMed1998

The inhibitory effects of IFN alpha-2b on EGFR expression and growth of cultured subconjunctival fibroblasts.

To investigate to what extent the growth of cultured subconjunctival fibroblasts was regulated by epidermal growth factor receptor (EGFR), we observed the expression of EGFR inhibited by interferon alpha-2b (IFN alpha-2b) and determined the growth of cultured subconjunctival fibroblasts by immunohistochemical and MTT methods. The linear relationships between the concentration of IFN alpha-2b and EGFR expression or growth were y = 1252.7-554.61 lgx (r = -0.98, P < 0.01), y = 0.523-0.0421 lgx (r = -0.93, P < 0.05) respectively. The concentration of IFN alpha-2b at doubled IC50 to EGFR (6.55 x 10(3) IU/ml) only inhibited the cell growth by 25.13%. The results suggested that the growth of subconjunctival fibroblasts may be controlled by many other growth factors because it was only partially inhibited by decreasing EGFR expression.

Animals↗
PubMed1998

Genetic variability and characterization of non-structural region 5 of hepatitis C virus genome from Chinese patients.

Sequence variation in the putative non-structural region 5b (NS5b) of hepatitis C virus (HCV) was analyzed in China. Complementary DNA fragments from sera of 49 Chinese patients were amplified by polymerase chain reaction (PCR) and the products were cloned and sequenced. Based on the comparison in NS5b of 33 clones of genotype 1b and 16 clones of genotype 2a, Chinese isolates of HCV belong to the same subtype as HCV-J, and HC-J6 from Japan. There does exist, however, some heterogeneity in the primary structure of the nucleotide acid. Higher homology was found among Chinese isolates than among Chinese isolates and Japanese isolates. Furthermore, among Chinese isolates, we found some conserved nucleotide acid positions different from those of Japanese isolates. Comparison of average homology among the 33 clones of genotype 1b and the 16 clones of genotype 2a indicated that the average homology among genotype 2a was lower than that among genotype 1b. In addition, a deletion of three nucleotide acids and a frame-shift, resulting in the introduction of an in-frame stop codon, were first observed in the NS5b region. These results indicated geographical differences in the distribution of individual HCV isolates, and the existence of a local variant in the same subtype. Our findings also suggested the need for further study on the sequence of genotype 2a, to improve diagnosis and help to advance the development of a vaccine.

Adult↗