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Biomedical subjects

L Li

Publications and source records attributed to L Li.

At least 1,585 records · Page 88Linked to original sources
PubMed1995

[Poliomyelitis surveillance in Shandong Province from 1991-1994].

After a series of poliomyelitis outbreaks came about in Shandong province from 1988 to 1990, comprehensive measures including establishment of acute flaccid paralysis (AFP) surveillance system, introduction of mass immunization campaign of oral poliovirus vaccine (OPV) and enhancing management of poliomyelitis eradication activity, were carried out. The incidence of poliomyelitis decreased with the reported number of cases 95, 25, 22 and 17, in 1991, 1992, 1993 and 1994, respectively. A geographically sporadic distribution was noticed with no peak on seasonality. No confirmed case caused by wild poliovirus was identified from 1991 to 1994. Reporting incidence of AFP cases among children under 15 years old was increasing gradually with 1.00 per 10(5) population in 1993 and 1.89 in 1994. The results showed that the poliomyelitis eradication activity in Shandong province had reached a final stage but much efforts still need to be made to reach the target on poliomyelitis eradication.

Adolescent↗
PubMed1995

[A study on protein metabolism in nephrotic patients treated with Chinese herbs].

It was found in our previous studies that two Chinese herbs Astragali and Angelica (A&A) together with high protein diet could ameliorate the lowering of serum albumin level and increase the synthesis rate of protein as shown by 15N-glicine tracer priming protein turnover study in nephrotic rats. Further experiment was designed to investigate the role of A&A and high protein intake in protein dynamic study and nitrogen balance in nephrotic patients. The level of serum total protein (STP), serum albumin (SA), urinary protein loss (UP), serum cholesterol (Cho) and index number of protein turnover and nitrogen balance in 7 patients were measured before and after treatment of 30 days with A&A. The results showed that after treatment the patients had significantly increased STA and SA (44.3 +/- 5.60 vs 49.7 +/- 6.80 P < 0.01; 22.6 +/- 0.42 vs. 29.4 +/- 7.40 P < 0.05), decreased UP and Cho (6.54 +/- 1.83 vs 4.63 +/- 1.33 P < 0.05; 9.69 +/- 2.31 vs. 7.82 +/- 1.95 P < 0.05) and increased net rates of total protein synthesis (1.06 +/- 0.03 vs 1.27 +/- 0.12 P < 0.05). It is concluded that A&A together with high protein intake could improve the disorder of protein metabolism and increase the level of serum protein by improving the net rate of protein synthesis in nephrotic patients.

Adult↗
PubMed1995

[Point mutation of p53 and detection of human papillomavirus DNA in bronchogenic carcinoma].

The p53 gene has been implicated in the pathogenesis of lung cancer as a tumor suppressor gene. Aberrations of the p53 gene (exon 6-8) was examined in 34 surgical specimens of lung cancer with single-strand-conformation-polymorphism analysis of polymerase chain reaction products. Structural abnormalities of the p53 gene were observed in 30 tumor specimens (88.2%), i.e, in 10 of the 12 specimens with squamous cell carcinoma, 8 of the 10 with adenocarcinoma, all the 3 small cell carcinoma, the only one large cell carcinoma, all the 5 alveolar cell carcinoma and all the 3 adenosquamous carcinoma. The aberrations of the p53 gene were not limited to a particular histological type or clinical stage and were not associated with degree of differentiation or history of heavy smoking. It is suggested that high mutation rate of the p53 gene may participate in the genesis of lung cancer. In this study, multiple primer polymerase chain reaction method was applied to detect the human papillomavirus DNA (HPV DNA) in human lung cancer. Only 4 of these 34 specimens were HPV DNA positive, and they were all of squamous cell carcinoma, 3 of them had p53 mutation.

Adenocarcinoma↗
PubMed1995

[Clinical effects of bisoprolol in congestive heart failure due to dilated cardiomyopathy].

Bisoprolol was administered orally at doses of 1.25-5 (mean 3.2 +/- 1.1)mg/day for 3-10 (mean 4.1 +/- 1.6) months in 19 patients with congestive heart failure secondary to dilated cardiomyopathy. All patients heart rate and blood pressure were sensitive to the first dose 1.25 mg bisoprolol and when the dose was titrated to 2.5 mg, it was effective and led to a smooth course during a 10-hour period of observation. After treatment, the patients heart function, including fractional shortening, ejection fraction and exercise ability increased significantly and both the severity and the incidence of ventricular arrhythmias decreased significantly. The response of heart rate to exercise and isoproterenol infusion tended to be normal lymphocyte beta-adrenergic receptor density was increased. It is shown that bisoprolol is a promising beta-blocking agent in treating congestive heart failure. The mechanisms of its effects may be related to depression of excessive sympathetic activity, decrease of heart rate and up-regulation of beta-adrenergic receptor.

Adrenergic beta-Antagonists↗
PubMed1995

[Immunohistochemical study of hepatitis C virus (HCV) antigen in liver tissue of patients with HCV infection].

Hepatitis C virus antigen (HCV Ag) and HCV-NS3 protein in paraffin-embedded liver tissue of patients with HCV infection were detected with immunohistochemical method by using polyclonal anti-HCV and monoclonal anti-HCV-NS3 for studying the expression of HCV in liver tissue. The results showed that the detection rate of HCV Ag and HCV-NS3 were 38.3% and 30.0% respectively. All the specimens with HCV-NS3 positive tissue were also those with HCV Ag positive. The stained substance located in the cytoplasm of liver cell, and the stained cells distributed scattered, clustered or diffuse in liver lobular. No obvious infiltration or necrosis was observed around the positive cells. There was obvious difference of the detection rate between different models of serum HCV markers. These results provided some help in understanding the pathogenesis of HCV.

Adolescent↗
PubMed1995

[Hemodynamic and renal effects of strong diuretic atrial natriuretic peptide in patients with acute myocardial infarction].

The hemodynamic and renal effects of strong diuretic atrial natriuretic peptide (ANP) were investigated in 12 patients with acute myocardial infarction. Strong diuretic ANP was administered as a bolus injection of 100 micrograms and followed by a continuous infusion of 2 micrograms/kg within 10 minutes into the right atrium via a catheter. We found that strong diuretic ANP induced an increase in cardiac index and stroke volume index. Right atrial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, systemic vascular resistance and pulmonary vascular resistance were decreased after ANP infusion. The maximal responses were observed immediately after the infusion was completed. No significant change of arterial blood pressure and heart rate was observed. Furthermore, strong diuretic ANP also increased the urine volume, urinary sodium, urinary chloride and urinary potassium. These results suggest that strong diuretic ANP infusion may induce significant changes of hemodynamics and may be used to prevent the development of severe circulatory volume overload in patients with AMI.

Adult↗
PubMed1995

[Chemical constituents of Cyclocarya paliurus (Batal.) Iljinsk].

Four compounds were isolated from the leaves of Cyclocarya paliurus. They were identified as daucosstero, beta-L-arabopyranose, steraric acid and palmitic acid on the basis of spectral data and chemical properties. All of them were isolated from this plant for the first time.

Drugs, Chinese Herbal↗
PubMed1995

Clinical and pathologic studies on idiopathic uveal effusion.

In order to investigate the clinical features, pathology and treatment of idiopathic uveal effusion syndrome, ten eyes of seven patients with the syndrome had been studied. In addition to general clinical examinations, indirect opthalmoscopy, fundus fluorescein angiography and (FFA) ultrasonography were used to make definite diagnoses. The findings of these examinations indicate four key features of the idiopathic uveal effusion syndrome. They are: annular cilio-choroidal detachment, shifting non-rhegmatogenous retinal detachment, unremarkable inflammation in the anterior segment, and normal intraocular pressure. The fundus change is characterized by the "leopard-spot". All patients were treated by sclerectomy and sclerotomy, ciliochoroidal detachments disappeared soon after surgery, and retinal detachments resolved later on. Patients' visual acuity recovered well. The histochemical and electron microscopic examinations of excised tissues from five eyes showed thickened sclera, a general increase of the scleral fibril width compared to normal scleral, the disruption of normal lamellar arrangement of the scleral fibers and the deposition of glycosaminoglycans in the interfibrillar spaces. All these indicate that a congenital scleral abnormality seems to be the basic pathophysiology of the idiopathic uveal effusion syndrome.

Adult↗
PubMed1995

L-tryptophan induces expression of collagenase gene in human fibroblasts: demonstration of enhanced AP-1 binding and AP-1 binding site-driven promoter activity.

Collagenase, a prototypic matrix metalloproteinase, plays a major role in the degradation of the extracellular matrix. The essential amino acid L-tryptophan was recently shown to stimulate the expression of collagenase gene in human dermal fibroblast cultures. In this study, we focused our attention on the mechanisms responsible for activation of collagenase transcription by L-tryptophan. Incubation of fibroblasts with L-tryptophan resulted in a dose- and time-dependent elevation of collagenase and tissue inhibitor of metalloproteinase mRNA levels. The maximum enhancement in collagenae mRNA was approximately 50-fold. This effect was not abolished by cycloheximide, suggesting independence from ongoing protein synthesis. Transient cell transfections with a promoter/reporter gene construct containing 3.8 kb of 5' flanking DNA of the human collagenase gene linked to the chloramphenicol acetyl transferase (CAT) gene or a construct containing three phorbol ester-responsive AP-1 binding sequences (12-O-tetradecanoyl-phorbol-13-acetate-responsive element) in front of the thymidine kinase promoter linked to the CAT gene indicated enhancement of promoter activity by L-tryptophan. Furthermore, electrophoretic DNA mobility shift assays demonstrated enhanced DNA-protein complex formation specific for an AP-1 binding site probe with nuclear extracts prepared from cells incubated with L-tryptophan. These results collectively suggest that activation of collagenase gene expression in dermal fibroblasts by L-tryptophan is mediated through AP-1 binding elements in the collagenase gene promoter that are sufficient for gene response.

Binding Sites↗
PubMed1995

Evaluation of screening kits for the detection of anti-human immunodeficiency virus type 1 and 2 (HIV-1/2) antibodies.

HIV-1/HIV-2 3rd generation (Abbott), Wellcozyme HIV 1 + 2 (Murex), Enzygnost Anti-HIV 1/-HIV 2 (Behring), and Genelavia Mixt (Sanofi Diagnostics Pasteur) are currently registered by authorities as enzyme immunoassays (EIAs) for detecting HIV-1/2 infection. The present study dissects these reagents by means of the major antigenic components, assay principles and their actual performance. The performances have been evaluated by their test results in international panels of seroconversion, mixed titer performance and HIV-1/2 combination, respectively. Those EIA tests were further used to examine 26 potentially false-reacting samples, serial diluted sera prepared from two confirmed positive specimens and 720 specimens obtained from random blood donors in the Taipei Blood Center, Chinese Blood Services Foundation (CBSF). The results showed that, although standard sera of the mixed titer, performance and HIV-1/2 combination rows could not distinguish significantly among various EIAs, the seroconverting samples clearly showed their differences. The differences, as calculated by using 3 of 4 seroconverting sera, was a backward window period ranging from 19 to 23 days as compared to the detection of HIV-1 antigens. Together, these studies strongly suggest that assays which are capable of detecting HIV-specific IgM and IgG antibodies have a shorter seroconversion window. Furthermore, the HIV-2 antigen seems to be crucial for successful detection of anti-HIV-2. Finally, testing anti-HIV-1/2 in the routine screenings is expected not to increase the exclusion rate of blood units currently acquired from the examination of anti-HIV-1. Consequently, with both HIV-1/2 specificities and the ability of early detection, IgM/IgG-captured EIAs may represent a better screening method than assays based solely on the detection of HIV-specific IgG.

Blood Donors↗
PubMed1994

Phytochrome assembly in living cells of the yeast Saccharomyces cerevisiae.

The biological activity of the plant photoreceptor phytochrome requires the specific association of a linear tetrapyrrole prosthetic group with a large apoprotein. As an initial step to develop an in vivo assay system for structure-function analysis of the phytochrome photoreceptor, we undertook experiments to reconstitute holophytochrome in the yeast Saccharomyces cerevisiae. Here we show that yeast cells expressing recombinant oat apophytochrome A can take up exogenous linear tetrapyrroles, and, in a time-dependent manner, these pigments combine with the apoprotein to form photoactive holophytochrome in situ. Cell viability measurements indicate that holophytochrome assembly occurs in living cells. Unlike phytochrome A in higher plant tissue, which is rapidly degraded upon photoactivation, the reconstituted photoreceptor appears to be light stable in yeast. Reconstitution of photoactive phytochrome in yeast cells should enable us to exploit the power of yeast genetics for structure-function dissection of this important plant photoreceptor.

Apoproteins↗
PubMed1994

Insertion and deletion mutants of FokI restriction endonuclease.

FokI restriction endonuclease recognizes the nonpalindromic pentadeoxyribonucleotide, 5'-GGATG-3':5'-CATCC-3' in duplex DNA and cleaves 9 and 13 nucleotides away from the recognition site. We have reported the presence of two distinct and separable protein domains within this enzyme: one for the sequence-specific recognition of DNA (the DNA binding domain) and the other for the endonucleases activity (the cleavage domain). Our studies have suggested that the two domains are connected by a linker region, which appears to be amenable for repositioning of the DNA-sequence recognition domain with respect to the catalytic domain. Here, we report the construction of several insertion (4-, 8-, 12-, 18-, 19-, or 23-amino acid residues) and deletion (4- or 7-amino acid residues) mutants of the linker region of FokI endonuclease. The mutant enzymes were purified, and their cleavage properties were characterized. The mutants have the same DNA sequence specificity as the wild-type enzyme. However, compared with the wild-type enzyme, the insertion mutants cleave predominantly one nucleotide further away from the recognition site on both strands of the DNA substrate. The four-codon deletion mutant shows relaxed specificity at the cut site while the seven-codon deletion appears to inactivate the enzyme. The DNA binding and cleavage domains of FokI appear to be linked by a relatively malleable linker. No simple linear relationship exists between the linker length and the distance of the cut site from the recognition site. Furthermore, the four-codon insertion mutants cleave DNA substrates containing hemi-methylated FokI sites; they do not cleave fully methylated substrates. These results are best explained as a consequence of protein-protein interactions between the domains.

Amino Acid Sequence↗
PubMed1994

Proteolytic activity of an antibody light chain.

The light chain (L chain) of a mAb raised against unactivated vasoactive intestinal peptide (VIP) hydrolyzed this peptide, whereas the heavy chain (H chain) and an irrelevant L chain were without activity. The reaction kinetics were consistent with efficient substrate recognition by the anti-VIP L chain compared with conventional proteases. The L chain cleaved four peptide bonds clustered between residues 16 and 21 in VIP. Mixtures of the L chain with its H chain partner displayed reduced hydrolytic activity compared with the free L chain, suggesting that the H chain is a modulator of the catalytic activity. These observations suggest: 1) the immune system can generate catalytic sites in the L chain subunit of Abs found in response to polypeptide Ags, and 2) free L chains found in vivo could display an Ag-specific catalytic function.

Amino Acid Sequence↗
PubMed1994

IL-10 inhibits cytokine production, vascular leakage, and swelling during T helper 1 cell-induced delayed-type hypersensitivity.

The Th1 group of cytokines (IL-2, IFN-gamma, and lymphotoxin (LT)) is usually associated with delayed-type hypersensitivity (DTH), whereas Th2 cytokines (IL-4, IL-5, IL-6, and IL-10) often accompany Ab production. Strong DTH and Ab responses are often mutually exclusive, possibly because of negative regulation between the cytokine patterns. In vitro, IL-10 inhibits the production of cytokines by Th1 cells, and inflammatory mediators by monocytes/macrophages, suggesting that IL-10 may be a negative regulator for DTH. We have investigated the effect of systemic IL-10 on the DTH reaction (nonindurated, with edema and granulocytic infiltration) induced by injection of Th1, clones into mouse footpads. Mammalian mouse rIL-10 was purified to > 90% homogeneity. The apparent in vivo half-life of i.p. injected IL-10 was approximately 2 h. Systemically administered IL-10 inhibited the 24-h footpad swelling induced by allo- and Ag-specific Th1 clones to a variable degree, with the strongest effect coinciding with peak DTH swelling. IL-10 also inhibited footpad swelling induced by a secondary challenge in SRBC-primed mice by 25 to 40%. Inhibition of Th1-induced swelling was accompanied by a similar inhibition of vascular permeability, as measured by leakage of Evans blue. Levels of IL-2, IL-6, IL-10, IFN-gamma, and TNF-alpha/LT were elevated in footpads undergoing a DTH reaction. IL-10 treatment reduced the levels of Th1 cytokines (IL-2, IFN-gamma, and TNF-alpha/LT) as well as IL-6, that was probably synthesized by other cells as a result of Th1 activation. The correlation between the inhibition of footpad swelling and cytokine production suggested that the effect of IL-10 on DTH may be mediated through suppression of cytokine synthesis.

Animals↗
PubMed1994

Antitumor agents. 155. Synthesis and biological evaluation of 3',6,7-substituted 2-phenyl-4-quinolones as antimicrotubule agents.

A series of 3',6,7-substituted 2-phenyl-4-quinolones were designed and synthesized as antimitotic antitumor agents. All compounds showed cytotoxic effects (log GI50 < or = -4.0; log drug molar concentration required to cause 50% inhibition) against the growth of a variety of human tumor cell lines, including those derived from solid tumors such as non-small cell lung, colon, central nervous system, ovary, prostate, and breast cancers, when evaluated in the National Cancer Institute's 60 human tumor cell line in vitro screen. The most potent compound (26) demonstrated strong cytotoxic effects with GI50 values in the nanomolar or subnanomolar range in almost all the tumor cell lines. Compound 26 was also a potent inhibitor of tubulin polymerization and radiolabeled colchicine binding to tubulin, with activity comparable to those of the potent antimitotic natural products colchicine, podophyllotoxin, and combretastatin A-4.

Animals↗
PubMed1994

Sequence of the coding region of the bovine fibrillin cDNA and localization to bovine chromosome 10.

We report the cDNA sequence for the bovine gene for fibrillin corresponding to the human gene, fibrillin 1 (FBN1), and the localization of the gene to bovine chromosome 10 (syntenic group U5). The identity between the human and bovine sequences is 97.8% at the amino acid level and 92% at the nucleotide level. The bovine fibrillin sequence contains the same number and type of motifs as the human FBN1 sequence, including the same number of putative calcium binding sites. All of the motifs conform to the patterns demonstrated in the human sequence, and many of the differences in identity between the sequences are conservative.

Amino Acid Sequence↗
PubMed1994

Synthesis and biological evaluation of C-3'-modified analogs of 9(R)-dihydrotaxol.

Taxol (1) is considered a most exciting new drug in cancer chemotherapy. The promising antitumor activity of 9(R)-dihydrotaxol (3) encouraged us to further explore the structure-activity relationship of this new member of the taxane family. Studies indicated that the C-13 side chain of taxol is indispensable for antitumor activity and that the natural substitution pattern of a 2'(R)-hydroxy and a 3'(S)-acylamino group might be optimal. However, relatively little is known about the effects of the 3'-phenyl ring on activity. The synthesis and biological evaluation of analogs of 3 modified at the C-3' position are described. This study revealed that the 3'-phenyl ring was not required for activity and identified several compounds which had equal or greater in vitro and in vivo activity than taxol.

Animals↗