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Biomedical subjects

S B Li

Publications and source records attributed to S B Li.

At least 19 recordsLinked to original sources
PubMed2001

Distribution of trace elements in normal and tumor-bearing mice using the multitracer technique.

A multitracer solution obtained from the nuclear reaction of selenium with 25-MeV/nucleon 40Ar ions was orally administered to normal and tumor-bearing Balb/c male mice. After 96 h, the mice were sacrificed and the elemental distribution was determined in various tissues, organs, and blood. The uptake of Na, Rb, Ga, Sc, V, Cr, Mn, Co, Fe, Zn, Y, Zr, Tc, Ru, Ag, and In in normal and, except for zinc, in tumor-bearing mice was simultaneously detected. Most elements were distributed in about the same manner in the skin and liver of animals in both groups. The distribution of Rb, Ga, V, Cr, Tc, and In showed little or no significant differences between the two study groups. The distribution of Na, Mn, Fe, Ag, Sc, and Co showed significant differences between normal and tumor-bearing mice. In the blood, spleen, and kidney of the normal mice, there was good absorption of Na, Mn, Fe, Ag, Co, and Zn. In the heart, these elements were well absorbed, except for Na and Mn.

Animals↗
PubMed2001

[Genetic polymorphisms of 9 STR loci in Achang ethnic group in Yunnan Province].

Blood samples were collected from the unreleatled individuals in the Achang ethnic group in Yunnan Province. Genetic distribution for nine STR loci and amelogenin locus were determined in Achang ethnic group based on GeneScan. 96 samples were denatured of gel electrophoresis. The databanks in Achang ethnic group were generated by using GeneScan, genotyper, and genetic distribution analysis. 69 alleses and 166 genotypers were observed, with the corresponding frequency being 0.0050-0.6100 and 0.0100-0.3900. The average H is 0.7381. The comulated DP is 0.9999999. The comulated EPP is 0.9999989. The allele distribution of the loci was in good agreement with the Handy-Weibeng equilibrium. It is useful to establishing DNA databanks for studying gene natural resources, very valuable in the study of forensic science, anthropology and ethnic.

Amelogenin↗
PubMed2000

Enzymatic resolution of (S)-(+)-naproxen in a trapped aqueous-organic solvent biphase continuous reactor.

A trapped aqueous-organic biphase system for the continuous production of (S)-(+)-2-(6-methoxy-2-naphthyl) propionic acid (Naproxen) has been developed. The process consists of a stereoselective hydrolysis of the racemic Naproxen methyl ester by Candida rugosa lipase in a trapped aqueous-organic biphase system. The reaction has been carried out in a laboratory-scale continuous-flow stirred tank reactor (CSTR). The staring material has been supplied in and remaining substrate recovered by organic phase. YWG-C(6)H(5), a poorly polar synthetic support, has been employed to immobilize the lipase and to restrict the aqueous phase. Lipase immobilized on YWG-C(6)H(5) containing aqueous phase has been added into the CSTR to catalyze the hydrolysis. A dialysis membrane tube containing a continuous flow closed-loop buffer has been applied in the CSTR for the extraction of product and recruiting of the aqueous part consumed. Various reaction conditions have been studied. The activity of immobilized enzyme was effected by the polarity of support, the substrate concentration, logP value of organic phase and the product inhibition. At steady-state operating conditions, an initial conversion of 35% has been obtained. The CSTR was allowed to operate continuously for 60 days at 30 degrees C with a 30% loss of activity. The hydrolysis reaction yielded (S)-(+)-Naproxen with >90% enantiomeric excess and overall conversion of 30%.

Bioreactors↗
PubMed2000

[Enzymatic resolution of racemic naproxen in a low aqueous-organic biphase system].

A stereoselective hydrolysis of the racemic naproxen methyl ester by immobilized lipase from Candida rugosa in a low aqueous-organic biphase system was studied. Support polar, water content, the logP value of organic phase and product inhibition effected the activity of immobilized enzyme. According to these reaction conditions, a low aqueous-organic biphase system for the continuous production of (S)-(+)-Naproxen was developed. The reaction was carried out in a continuous-flow closed-loop 50 mL stirred bioreactor packed with YWG-C6H5, a poorly polar synthetic support on which the lipase had been immobilized by adsorption. The aqueous phase was permanently remained in the reactor associated with the immobilized enzyme particles; the organic phase containing substrate was pumped through this reactor and emerged with the products. The continous-flow stirred bioreactor containing 75 mg lipase was allowed to operate continuously for 60 days at 30 degrees C with a 25% loss of activity, 900 mg of (S)-(+)-Naproxen (eep 95%) were producted.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

[Genescan for STR analysis and genetic distribution in a population sample from Han, China].

Genetic distributions for nine STR loci and Amelogenin locus were determined in a Chinese Han population based on DNA sequencing. The databanks in Chinese Population were generated by using Genescan, genotype and genetic distribution analysis. Allele frequency distribution was determined for 10 loci, such as D3S1358, VWA, FGA, Amelogenin, THO1, TPOX, CSF1PO, D5S818, D13S317 and D7S820. The results show significant differences between ethnic groups (African-American, US-Caucasian and Chinese Han) in the pattern of distribution as well as in the related frequency of the most common alleles of their STR loci. The probabilities of identity values for the population described in this section are 2.79 x 10(-10) (U.S-Caucasian), 1.23 x 10(-10) (African-American) and 0.5 x 10(-10) (Chinese Han). The results show the probability of Paternity Exclusion (PPE) values of 0.9998 (Chinese Han), 0.9996 (African-American) and 0.9994 (U.S-Caucasian). These results suggested that the nine STR loci and the Amelogenin locus are very useful for human identification, such as analyzing forensis casework, establishing DNA databanks, processing paternity test, evaluation linkage genetics, studying gene natural resources and monitoring bone marrow transplants.

Asian People↗
PubMed2000

[Human DNA polymorphism of HaeIII system in Chinese oriental, Han population].

DNA typing by restriction fragment length polymorphism (RFLP) analysis was an extremely important technique used in forensic science identification, paternity test and gene diagnosis. While RFLP testing was a highly informative method, it traditionally had several disadvantages. It was time consuming and involved in working with radioactive phosphorus. A chemiluminescent detection of RFLP technique that was faster and safer than isotopic detection. The chemiluminescent system had a good sensitivity of detecting 3-25 ng sample DNA. The development of direct alkaline phosphatase (AP) conjugated probes and improved chemiluminescent substrates provided a non-isotopic detection method that equaled or surpassed 32P detection systems. Population genetic studies were performed using direct alkaline phosphatase (AP) conjugated oligonucleotide probes (AL1874, YNH24, TBQ7, VI) that recognized four hypervariable number of tandem repeats regions (D2S92, D2S44, D10S28, D17S79 loci) respectively in the human genome. DNA from approximately 480 unrelated individuals, subdivided into oriental group were digested with HaeIII enzyme and were successively hybridized to each DNA probe. The number of distinct DNA fragments identified for each of these regions varies from 37 to more than 78. An allele frequency distribution was determined for each locus with the computer and digitizer. The results showed significant differences between different races (American-blacks, Caucasians, and Orientals), in the pattern of distributions as well as in the relative frequency of the most common alleles of D2S92, D2S44, D10S28, and D17S79. The results showed that the analysis of these loci had useful applications in genetics and in forensic identity.

Alleles↗
PubMed2000

[STR polymorphisms in five Chinese ethnic groups(2)].

Population genetic studies were performed in Chinese Han, Hui, Mongolian, Tibetan and Uygur. Allele frequency distributions were analyzed for ten loci, i.e., D3S1358, VWA, CSF1PO, FGA, THO1, TPOX, D5S818, D13S317 and D7S820 by GeneScan. The results showed that there were 60 STR alleles and 149 genotypes in Han; 63 STR alleles and 144 genotypes in Hui; 69 STR alleles and 173 genotypes in Mongolian; 77 STR alleles and 168 genotypes in Tibetan; 70 STR alleles and 148 genotypes in Uygur. Significant differences were identified among ethnic groups (African-American, US-Caucasian and Chinese-Oriental), but similarity was found among the five Chinese populations, and immunogenomics and pharmacogenomics studied in this report. These findings indicated that the nine STR loci and amelogenin locus were very useful for individual identification in forensic science.

Alleles↗
PubMed1999

[HLA-DRB alleles polymorphism in Han, Hui, Uygur and Tibetan populations in northwestern China].

According to the 11th THW standard, we designed a pair of primers by which a segment of 256bp of HLA-DRB1, B3, B4, and B5 could be amplified simultaneously. Twenty-seven oligonucleotide probes were designed and synthesized for 39 loci on DRB1, 3 on DRB3, 1 on DRB4 and 3 on DRB5. A PCR-SSO DNA typing protocol was built, which met the standard of HLA class II DNA typing in 11th IHW. With this method, 186 of Chinese (Han) in Xi'an, 169 of Hui in Ningxia, 200 of Uygur in Xinjiang, and 188 of Tibetan in Tibet were detected with a comparison study. The genetic distribution of 46 loci of DRB in four ethnic healthy populations were surveyed. No diversity has been found between Han and Hui in DRB. DRB1 * 02(16.9%), DRB1 * 07 (13.1%), and DRB1 * 09(12.0%) were the higher frequent loci in Han. More DRB loci were detected in Tibetan but without higher loci as in Han and Hui. The DRB polymorphism of Uygur population was similar to Caucasian. A discriminative highest frequency of DRB1 * 07(23.8%) was found in Uygur, which implied a selection happened.

Alleles↗
PubMed1998

[Relationship between water content and magnetization transfer ratio in the rat brain using a new cardiac perfusion model with different osmotic gradients].

We devised a method to make a gradient water content model of the rat brain by perfusing osmotic NaCl solution from the left ventricule. Using this model we measured the water content and magnetization transfer ratio (MTR) of the frontal lobe and the pons as examples of gray and white matter, respectively. When we perfused five levels of osmotic NaCl solution (0, 0.9, 1.8, 3.6 and 7.2%) to respective groups of four rats, mean water content decreased from 81.5% at 0% to 75.9% at 7.2% NaCl in the frontal lobe and from 74.1% to 61.0% in the pons, while MTR increased from 21.5% to 24.2% in the frontal lobe and from 22.9% to 27.3% in the pons. Thus water content was significantly higher (p < 0.01) in the frontal lobe than the pons at each level of NaCl concentration, and MTR was significantly higher in the pons than the frontal lobe (p < 0.05 approximately 0.01, except at 0%). Further, the grade of alteration was higher in the pons than the frontal lobe for both water content and MTR. Excellent correlations between MTR and water content were observed with coefficients of -0.75 and -0.82 for the frontal lobe and pons, respectively, and the regression lines showed higher position and slope in the frontal lobe than the pons. From these results we concluded that the pons is rich in free water of extracellular fluid that moves easily between the myelin sheath, whereas in the frontal lobe, water is so diffusely mingled with membranes and favorable to bound water that the magnetization transfer effect is more effective, yielding a higher MTR for the same water content and showing greater change in MTR for the same change in water content as the pons.

Animals↗
PubMed1997

Effect of U-73122 on calcium channel activity in porcine myometrial cells and pancreatic beta-cell line RINm5F.

AIM: To study the effect of U-73122, putative phospholipase C (PLC) inhibitor, on cytosolic Ca2+ concentration ([Ca2+]i) and voltage-dependent calcium channels (VDCC). METHODS: To record whole cell calcium current (ICa) by perforated patch-clamp and to measure cytosolic free calcium concentration ([Ca2+]i) with Fura-2. RESULTS: U-73122 inhibited KCl-induced and Bay-K-8644-induced increase in [Ca2+]i dose-dependently. U-73122 decreased markedly depolarization-induced ICa both in RINm5F and porcine myometrial cells in a concentration-dependent manner. The effect of U-73122 was more potent in porcine myometrial cells than that in RINm5F cells. U-73343 (an analog of U-73122), that does not inhibit PLC, also reduced the ICa by 50%. CONCLUSION: U-73122 inhibited VDCC and [Ca2+]i in both RINm5F and porcine myometrial cells.

Animals↗
PubMed1994

An experimental study on the disturbance of liver circulation and the change of hemorrheology in dogs with acute liver damage.

The changes of hepatic hemodynamics and hemorrheology were investigated in dogs with acute liver damage induced by acetaminophen. There were remarkable disturbance in liver circulation and hemorrheological abnormality occurring in both slight and severe liver damage. The study indicated that the degree of disturbance in liver circulation as well as in hemorheological change is positively correlated with the severity of liver damage. For example, marked increase in blood viscosity linked with elevated fibrinogen level appeared in slight liver damage, whereas reduced blood viscosity associated with decreased plasma fibrinogen level and hematocrit occurred in severe liver damage. This study also revealed that the increase of portal venous resistance (PVR) and the disturbance of liver circulation in slight liver damage were chiefly related to the increase of blood viscosity and the increase of PVR in severe liver damage was mainly associated with the reduction of the radius of portal vein.

Acetaminophen↗
PubMed1993

Allelic loss in ovarian cancer.

Loss of heterozygosity (LOH) was examined at 86 loci distributed on every chromosomal arm in 50 human ovarian tumors. Frequent allele losses were observed on chromosomes 13q (42%), 17p (42%), 17q (45%), and Xp (41%). Deletion mapping on chromosome 17 revealed a candidate gene on the long arm distal to D17S41/S74 for ovarian cancer which is distant from the locus for early onset breast cancer. LOH on chromosome 17q was found to be concordant with LOH on chromosomes 3p, 13q, 17p and Xp suggesting that it may be an early event in neoplastic development. These findings indicate that multiple tumor-suppressor genes for ovarian cancer possibly exist on chromosomes 13q, 17, and/or Xp and provide the basis for the identification of candidate gene(s) associated with ovarian cancer. The chromosomal mechanisms resulting in allele losses in ovarian cancer include deletion, deletion/duplication, mitotic recombination and monosomy, in concordance with the developed genetic model.

Alleles↗
PubMed1992

Experimental studies on the changes of adrenergic receptors in rat liver with acute injury and in endotoxemia.

Previous studies suggested that hepatic alpha and beta adrenergic receptors is stable and it is in dynamic equilibrium under normal conditions. However, at a pathological condition these receptors may be changed. We studied the changes of adrenergic receptors in the rat liver with acute injury and in endotoxemia by light microscopic autoradiography. Our experimental results reveal that in the liver of rats with acute injury and in endotoxemia there were changes in varying degrees of alpha and beta adrenoceptors. Moreover, the changes were not uniform in various structures of the rat liver. Glucagon can keep adrenergic receptors stable on hepatic cells and muscular cells of blood vessels in the rat liver. Our experiment provides evidence for clinical use of adrenoceptor antagonists in the treatment of acute and chronic liver disease.

Animals↗
PubMed1991

Trisomy 12 and K-ras-2 amplification in human ovarian tumors.

Cytogenetic analysis was performed on 11 benign and borderline ovarian tumors. Trisomy 12, identified as a sole abnormality in 6 tumors, is likely a specific karyotypic change in different benign and borderline tumors and may well be a primary chromosomal lesion in these tumors. The possible association between amplification of the proto-oncogene K-ras-2 which is located on chromosome 12 and trisomy 12 was investigated. DNA blotting analysis of 64 tumors indicates that trisomy 12 does not seem to be related to K-ras-2 amplification in ovarian tumors. K-ras-2 amplification was observed in 3 high-grade tumors from 3 patients with metastases.

Chromosome Banding↗
PubMed1991

Allele loss at the retinoblastoma locus in human ovarian cancer.

To gain a broad spectrum on allelic loss of specific loci in ovarian tumors, we initially examined DNA from 23 pairs of ovarian tumors and matched peripheral blood lymphocyte samples from the same patients, using 27 polymorphic DNA markers distributed on 13 chromosomes. Significant high frequency of allelic deletion (22%-44%) at chromosome 13 loci (D13S31, D13S32, D13S33, and D13S34) at bands q12-q34 was observed in tumor tissues. These results led us to investigate the loss of heterozygosity at the retinoblastoma (RB) locus in ovarian tumors, because the RB gene is a tumor-suppressor gene located at 13q14. Analysis of the variable number of tandem repeat sequence polymorphism in intron 20 in the RB gene revealed that 6 (30%) of 20 patients with informative samples showed allelic loss at the RB locus in their tumor tissues. This loss, of relatively high frequency, suggests that the RB gene, or a closely linked gene, seems to be involved in the development of ovarian cancer.

Base Sequence↗
PubMed1991

The effect of anti-AFP-F(ab)'2 and adriamycin conjugate on transplantable tumors in mice.

Efficacy of the conjugate anti-AFP-F(ab)'2 with adriamycin, anti-AFP-F(ab)'2-adr, against transplantable tumors was studied in mice. The results showed that LD50 of anti-AFP-F(ab)'2-adr in mice was 7.43 mg/kg and that anti-AFP-F(ab)'2-adr in a dose of 1/10-1/5 LD50 could inhibit the growth of transplanted hepatocellular carcinoma. In addition, anti-AFP-F(ab)'2-adr with local application of AFP could markedly inhibit the growth of transplanted Ehrlich ascites cancer. From the above it is suggested that anti-AFP-F(ab)'2-adr can be used to treat hepatic carcinoma with satisfactory results.

Animals↗
PubMed1991

The effects of the combination of phentolamine and vasopressin on hepatic and systemic hemodynamics in cirrhotic portal hypertensive dog model.

The experimental study was aimed at elucidating the effects of phentolamine and vasopressin used separately or in combination on hepatic and systemic hemodynamics in cirrhotic portal hypertensive dogs. The results showed that either of the two drugs used separately could lead to reduction in portal venous pressure and could also influence systemic hemodynamics or lower hepatic blood flow. When phentolamine in combination with vasopressin was administered, no side-effect could be found on hepatic and systemic hemodynamics, suggesting that the drugs used in combination could efficaciously decrease portal hypertension and counteract their respective side-effect. This combination therapy will be useful in treating bleeding from esophageal variceal rupture in cirrhotic patients with portal hypertension.

Animals↗