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Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 793 records · Page 44Linked to original sources
PubMed1999

[Detection of human papillomavirus gene in biopsies from colon carcinoma by PCR].

OBJECTIVE: To detect the human papillomavirus gene (HPVs) in biopsies from colon carcinoma by PCR and to study the relationship between HPV infection and colon carcinoma. METHODS: 46 biopsies from colon carcinoma, 10 biopsies from tissue around carcinoma and 16 control biopsies were collected and DNA were extracted. The HPV DNA in biopsies were amplified by PCR using general primers (GP) and primers for HPV6/11, HPV16/33 and HPV18. RESULTS: 20 out of 46 biopsies from colon carcinoma showed HPV gene positive, HPV6/11, HPV6/33 and HPV18 positivity were 3, 11 and 6 respectively. HPV DNA was found in 1 case from 10 biopsies of surrounding tissue of carcinoma. 16 control biopsies were negative. CONCLUSION: HPV may be related to the etiology of colon carcinoma.

Colorectal Neoplasms↗
PubMed1999

[The absorption spectra of crystal thin film Cs3Cu2I5].

In this paper we measured the absorption spectra of crystal thin film Cs3Cu2I5 at room and liquid nitrogen temperatures, respectively, and calculated the excitonic coefficient of the material. The excitonic coupling energy deltaE(ex)(1) = (0.53 +/- 0.07) eV, excitonic radius a(ex) = 0. 326 nm,and forbidden zone width E(g) = (5.00 +/- 0.07) eV. The spectral analysis shows that the electron and exciton excitations of the Cs3Cu2I5 localize in the CuI subcrystal lattice, and reveals the law that governs the variance of the first excitonic peak position of the serial Cs(x)Cu(1-x) I compounds with their mol-components at low temperature.

English Abstract↗
PubMed1999

[Effect of the coordinate micro-environment on the structure of Hg (II)-serum albumin].

Detailed studies on the UV spectra of Hg (II)-HSA or Hg (II)-BSA complexes nearby isoionic point were carried out in this paper. Compared with the spectra at physiological pH, the band nearby 250 nm of Hg (II)-BSA generally disappeared or widened and weakened,but the band at 290 nm of Hg (II)-BSA and Hg (II)-HSA remained nearly unchanged. These results support that these binding sites of Hg (II)-serum albumin may be located at seven pairs of adjacent disulfide bridges and there might be the structure of HgS4 tetrahedral configuration. For the first time, this paper put forward the solid figure of HgS4 tetrahedral configuration, and further discussed the results using the discrepancy of the coordinate micro-environment.

Animals↗
PubMed1999

[Study on the interaction of human serum albumin and Mn (II), Co (II) by fluorescence method].

The interaction of Mn (II), Co(II) and HSA has been studied by fluorescence method at pH 7.4 and 5.3. Based on Forste non-radiative energy transfer theory, the distance between Trp-214 residue of HSA and the first strong binding site to Mn (II), Co (II) in HSA was determined, and it is much larger than that of reference. This notable different result has been discussed according to the binding site of Mn (II), Co (II ) and domain structure in HSA.

Binding Sites↗
PubMed1999

Chemical synthesis of D-ribo-phytosphingosine-1-phosphate, a potential modulator of cellular processes.

d-erythro -Sphingosine-1-phosphate (2), an intermediate in sphingosine metabolism, shows a diversity of biological activities. Comparable roles might be anticipated for d-ribo -phytosphingosine-1-phosphate (1). We describe an efficient three-step chemical synthesis of 1 from d-ribo -phytosphingosine. Our approach is based on standard phosphoramidite methodology and on the finding of Boumendjel and Miller ( J. Lipid Res. 1994. 35: 2305-2311) that sphingosine can be monophosphorylated at the 1-hydroxyl without protection of the 3-hydroxyl. However, we were unable to duplicate their reported synthesis of 2 without important modifications in reagents and reaction conditions. Under the reported conditions for preparing 2, we obtained a cyclic carbamate (14), which we have isolated and identified. The structures of 1 and the cyclic carbamate 14 were elucidated by a combination of mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy.

Animals↗
PubMed1998

Modulatory impact of cardiac rehabilitation on hyperhomocysteinemia in patients with coronary artery disease and "normal" lipid levels.

In coronary patients with "relatively normal" lipid values and hyperhomocystinemia (levels > or =15 micromol/L), significant 12% reductions in homocysteine levels occurred after cardiac rehabilitation and exercise training. This benefit from cardiac rehabilitation and exercise training may lead to 20% to 30% reductions in overall coronary artery disease risk.

Aged↗
PubMed1998

[Association of VNTR region of the human serotonin transporter gene with bipolar disorder among the Han Chinese].

OBJECTIVE: The serotonin transporter gene (SERT) plays an important role in the serotonin uptake into neurons. This paper reports a population and association study among the Han Chinese. METHODS: DNA were extracted from peripheral blood samples of 50 patients with bipolar disorder (DSM-IIIR), 170 unrelated healthy Han Chinese individuals and 10 healthy trios for polymerase chain reaction. The VNTR locus was amplified and PCR products were separated on the 2% agrose gel. RESULTS: All the three alleles(9,10 and 12 copies of repeat unit) reported in other studies were observed in this study with frequency 0.0029, 0.0676 and 0.9294, respectively. Four genotypes distributed in Caucasian: 12/12, 12/10, 12/9 and 10/10 were also found in the Han Chinese population. A significant difference in the allele frequency between the Han Chinese and Caucasian populations was found(P 0.000000001). No disequilibrium was observed after checking the Hardy-Weinberg equilibrium (P=0. 9995). The hereditary stability of this locus in accordance with the rules of Mendelian inheritance was demonstrated in the analysis of ten trios. In addition, a significant increase of frequency of the allele 10 in female patients with bipolar disorder was found (P=0. 043). CONCLUSION: The data of association study might indicate a different mechanism of aetiology of bipolar disorder in male and female.

Asian People↗
PubMed1998

[The polymorphism of two microsatellites closely linked to the locus for polycystic kidney disease 1 in Chinese population].

OBJECTIVE: To evaluate the polymorphism of AC2.5 and SM7, two microsatellite markers closely linked to the locus for polycystic kidney disease 1 (PKD1), in the Han (Chinese majority) and the Zhuang(the largest minority in China) populations and make clear whether the allele frequencies of these markers exhibit significant differences between populations. METHODS: The two microsatellite markers were amplified by polymerase chain reaction(PCR), followed by 10% non-denatured polyacrylamide gel electrophoresis(PAGE) and DNA sequencing to analyze the PCR products. RESULTS: (1) Ten AC2.5 alleles and eleven SM7 alleles were observed in 104 Chinese Han people, and eight AC2.5 alleles and nine SM7 alleles were observed in 75 Chinese Zhuang people. (2) The expected heterozygosities of AC2. 5 and SM7 were 68.4% and 77.4% in the Han population and 67.1% and 57.5% in the Zhuang population respectively. The polymorphism information content(PIC) values of them were 0.68 and 0.77 in the Han population and 0.67 and 0.57 in the Zhuang population respectively. (3) Several allele frequencies of the two markers exhibited significant differences between populations(P 0.05). CONCLUSION: AC2.5 and SM7 are highly polymorphic and can be used in genetic diagnosis of both Chinese Han and Zhuang PKD1 families. The allele frequency distributions of them exhibit significant difference between populations.

Alleles↗
PubMed1998

Different systems in human brain are involved in presemantic discrimination of pictures as revealed by event-related potentials.

It is uncertain if the several brain areas in response to presemantic picture processing are functionally homogeneous. Subjects were asked to discriminate visual stimulus pairs and event-related potentials (ERPs) were recorded from the scalp. A line-drawing picture (S1) was followed by another stimulus (S2) 600 ms later. S2 was the same as S1 in condition 1, a reversed picture of S1 in condition 2, the corresponding Chinese word in condition 3 and the syllabic alphabet of S1 in condition 4. Amplitudes of ERPs over right posterior scalp with time window from 102-180 ms after the onset of S2 in condition 1 and 2 were significantly larger than condition 3 and 4. The N2 component on the right anterolateral scalp with time window from 182-240 ms was significantly larger in condition 1 than other conditions, whereas the N2 on the left anterolateral scalp with time window from 262-350 ms in condition 2, 3 and 4 was significantly larger than condition 1. It is suggested that pictures and words are processed in different systems at the presemantic stage: repetitive and physically deviant stimuli evoke different responses in different brain regions.

Adult↗
PubMed1998

The yeast histidine protein kinase, Sln1p, mediates phosphotransfer to two response regulators, Ssk1p and Skn7p.

The Saccharomyces cerevisiae Sln1 protein is a 'two-component' regulator involved in osmotolerance. Two-component regulators are a family of signal-transduction molecules with histidine kinase activity common in prokaryotes and recently identified in eukaryotes. Phosphorylation of Sln1p inhibits the HOG1 MAP kinase osmosensing pathway via a phosphorelay mechanism including Ypd1p and the response regulator, Ssk1p. SLN1 also activates an MCM1-dependent reporter gene, P-lacZ, but this function is independent of Ssk1p. We present genetic and biochemical evidence that Skn7p is the response regulator for this alternative Sln1p signaling pathway. Thus, the yeast Sln1 phosphorelay is actually more complex than appreciated previously; the Sln1 kinase and Ypd1 phosphorelay intermediate regulate the activity of two distinct response regulators, Ssk1p and Skn7p. The established role of Skn7p in oxidative stress is independent of the conserved receiver domain aspartate, D427. In contrast, we show that Sln1p activation of Skn7p requires phosphorylation of D427. The expression of TRX2, previously shown to exhibit Skn7p-dependent oxidative-stress activation, is also regulated by the SLN1 phosphorelay functions of Skn7p. The identification of genes responsive to both classes of Skn7p function suggests a central role for Skn7p and the SLN1-SKN7 pathway in integrating and coordinating cellular response to various types of environmental stress.

DNA-Binding Proteins↗
PubMed1998

Tsetse thrombin inhibitor: bloodmeal-induced expression of an anticoagulant in salivary glands and gut tissue of Glossina morsitans morsitans.

The tsetse thrombin inhibitor, a potent and specific low molecular mass (3,530 Da) anticoagulant peptide, was purified previously from salivary gland extracts of Glossina morsitans morsitans (Diptera: Glossinidae). A 303-bp coding sequence corresponding to the inhibitor has now been isolated from a tsetse salivary gland cDNA library by using degenerate oligonucleotide probes. The full-length cDNA contains a 26-bp untranslated segment at its 5' end, followed by a 63-bp sequence corresponding to a putative secretory signal peptide. A 96-bp segment codes for the mature tsetse thrombin inhibitor, whose predicted molecular weight matches that of the purified native protein. Based on its lack of homology to any previously described family of molecules, the tsetse thrombin inhibitor appears to represent a unique class of naturally occurring protease inhibitors. Recombinant tsetse thrombin inhibitor expressed in Escherichia coli and the chemically synthesized peptide are both substantially less active than the purified native protein, suggesting that posttranslational modification(s) may be necessary for optimal inhibitory activity. The tsetse thrombin inhibitor gene, which is present as a single copy in the tsetse genome, is expressed at high levels in salivary glands and midguts of adult tsetse flies, suggesting a possible role for the anticoagulant in both feeding and processing of the bloodmeal.

Amino Acid Sequence↗
PubMed1998

Transgenic mice demonstrate a testis-specific promoter for lactate dehydrogenase, LDHC.

The mammalian genome encodes a family of lactate dehydrogenase (LDH) isozymes. Two of these, ldha and ldhb, are expressed ubiquitously. The ldhc gene is active only in the germinal epithelium during spermatogenesis. In our analysis of ldhc gene regulation, we found that a 60-base pair promoter sequence was sufficient for testis-specific expression in an in vitro transcription assay. To confirm these findings, a genomic fragment containing 100 base pairs overlapping the transcription start site was isolated and linked to the Escherichia coli lacZ gene. We report that this genomic fragment drives testis-specific expression in transgenic mice. We conclude that transcription of the transgene and possibly of the endogenous ldhc gene is restricted to leptotene/pachytene primary spermatocytes.

Animals↗
PubMed1998

The clinical implications of no reflow demonstrated with intravenous perfluorocarbon containing microbubbles following restoration of Thrombolysis In Myocardial Infarction (TIMI) 3 flow in patients with acute myocardial infarction.

Intravenous injections or infusions of perfluorocarbon-exposed sonicated dextrose albumin microbubbles were given 2.4 +/- 1.6 days following acute myocardial infarction to 45 consecutive patients. Patients were divided into 3 groups: patients with Thrombolysis In Myocardial Infarction (TIMI) grade 3 angiographic flow but persistent myocardial contrast defects by echocardiography (no reflow), patients with TIMI 3 flow and myocardial contrast enhancement (reflow), and patients with TIMI grade 0 to 2 flow in the infarct vessel. Thirty-five patients had TIMI 3 flow at the time of contrast study. Of these, 25 had evidence of reflow with intravenous contrast, whereas 10 (29%) still had contrast defects. At follow-up, end-systolic volume index decreased significantly in patients who exhibited reflow (21 +/- 8 ml/m2 at baseline to 18 +/- 8 ml/m2 at follow-up; p = 0.04), whereas those with no reflow had a significant increase (26 +/- 9 ml/m2 at baseline to 32 +/- 9 ml/m2 at follow-up; p = 0.006). A persistent contrast defect in the infarct zone demonstrated with intravenous ultrasound contrast following restoration of TIMI grade 3 flow in the infarct vessel identified patients likely to have deterioration in both regional and global systolic function.

Aged↗