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Biomedical subjects

L F Wang

Publications and source records attributed to L F Wang.

At least 19 recordsLinked to original sources
PubMed1992

Expression of a gene encoding a rabbit sperm membrane protein in mammalian cells.

A general mammalian expression vector designated pSV2-EP was reconstructed by inserting an oligonucleotide fragment into pSV2-dhfr. This vector allowed insertion of cDNAs with EcoRI cohesive ends. The pSV2-EP contains a simian virus 40 (SV40) early promoter, origin for DNA replication, SV40 poly-A site, splicing site, an initiator ATG downstream from the promoter and an EcoRI site for the insertion of cDNA fragment screened from lambda gt11 expression libraries. A recombinant plasmid (pS-VRS-1) was constructed by inserting RSD-1, a cDNA encoding a rabbit sperm tail protein, into the EcoRI site of the pSV2-EP vector. Chinese hamster ovarian (CHO) dhfr-negative cells were cotransformed with pSV2-dhfr and pSVRS-1 by the calcium phosphate method. In selective culture medium without thymidine and hypoxanthine, several cell lines were obtained containing mRNA and DNA that hybridized with RSD-1. One of these transformed cell lines stained intensely with anti-rSMP-B antibodies, demonstrating that the RSD-1 was expressed in the transformed CHO cells.

Animals↗
PubMed1992

Isolation and sequencing of the cDNA encoding the 75-kD human sperm protein related to infertility.

Serum was obtained from an infertile woman (IS) inducing head-to-head agglutination of human sperm and was used to screen a human testis lambda gt11 cDNA library. A plaque producing the interacting antigen was located. The recombinant lambda gt11 was isolated and cut with EcoRI releasing a 0.7-kb cDNA. Using the 0.7-kb cDNA as a probe, a larger cDNA of 2.4 kb was isolated and its nucleotide sequence determined. It was composed of 2 427 nucleotides with an open reading frame of 1584 nucleotides encoding 528 amino acid residues. The specific antisperm antibody was isolated from IS by epitope selection, using positive plaques of E. coli Y1090. The epitope-selected antibodies interacted with a 75-kD human sperm protein and with a polypeptide in the form of a beta-galactosidase fusion protein in the recombinant lysate of E. coli Y1089, determined by immunoblot. The fusion protein was purified by affinity chromatography on an anti-beta-galactosidase-Sepharose column. It is proposed that production of anti-75-kD antibodies may be the underlying cause of the infertility.

Amino Acid Sequence↗
PubMed1992

[Determination of nifedipine by differential spectrophotometry].

This paper reports a new method for determining nifedipine based on the unstable character of nifedipine to light. The absorbance was measured at 350 nm before and after light irradiation. In this method, the contents of nifedipine in tablets were determined by differential absorbance (delta A) and the assay of nifedipine was not affected by other components. Calibration graph was linear in the range of 10-60 micrograms/ml for delta A. The precision of the method was: 1.3% within-day and 1.9% between-days. The average recovery for nifedipine was 99.69%. The method is not only better in specificity and repeatability but also simple and rapid, it would be a new way of assay for nifedipine.

Nifedipine↗
PubMed1992

[The photodegradation-assay method of sodium nitroprusside and its application to studies on percutaneous absorption].

A new method of quantitative analysis of sodium nitroprusside (SNP) was developed according to the principle of a photodegradation analytical method that has been reported by the authors previously. After irradiated of solution of SNP under fluorescent lamp, the increase in absorbance at 394 nm belonged to nonlinear kinetics, but the absorbance increment with concentration was linear in certain concentration range of SNP. When irradiated for 30 min or 60 min, SNP in solution can be quantitated accurately by delta A394. The standard curve of this method was linear from 50 to 1000 mg/L. The within-day and day-to-day precisions (RSD) were 1.9% and 2.6% respectively, with recoveries of 99.0-100.1%. No interference from small amount of serum protein, stearyl alcohol, propylene glycol, azone, m-nifedipine, nitrendipine and verapamil was observed. This method has been successfully applied to study percutaneous absorption.

Animals↗
PubMed1992

[Clinicopathological study of osteosarcoma of the jaw].

Eighty-five cases of osteosarcoma of the jaw were analyzed for clinical and histologic characters. According to the predominant histologic differentiation of the tumor, it was divided into osteoblastic, chondroblastic and fibroblastic type. Chondroblastic osteosarcoma was associated with the worst survival rate. The histologic grade was closely related to the prognosis of tumor.

Adolescent↗
PubMed1992

Nucleolar organizer regions in aspirates of malignant lymphomas and benign disorders of the lymph nodes.

Silver staining of nucleolar organizer regions (AgNOR) was used to differentiate malignant lymphoma and chronic lymphadenitis. Aspiration smear samples from lymph nodes of 120 cases, including 43 non-Hodgkin's lymphoma, 3 Hodgkin's disease, 56 chronic lymphadenitis, 7 tuberculosis, 6 reactive hyperplasia and 5 samples from other diseases (epidermoid cyst, branchial cyst, mixed tumor, lymphoepithelioma and nodulous disease), were investigated. The number of AgNORs in 200 cells in each sample was counted, and the mean +/- SD in each disease was calculated: non-Hodgkin's lymphoma, 6.58 +/- 2.37; Hodgkin's disease, 4.22 +/- 0.5; chronic lymphadenitis, 1.16 +/- 0.1; tuberculosis, 1.13 +/- 0.14; reactive hyperplasia, 1.48 +/- 0.25; other diseases, 1.47 +/- 0.31. The results indicate that the AgNOR count in malignant lymphoma differed highly significantly from that in benign disease (P less than .001). The size of AgNORs in malignant lymphoma and chronic lymphadenitis was measured, and the maximum diameter and area of lymphocyte and lymphoma cell were: lymphocyte, 0.93 +/- 0.12 microns, 0.61 +/- 0.13 microns 2; lymphoma cell, 0.83 +/- 0.22 microns, 0.50 +/- 0.25 microns 2. The AgNOR sizes in malignant lymphoma were significantly smaller than in chronic lymphadenitis (P less than .001).

Adolescent↗
PubMed1992

[Determination of m-nifedipine and its pharmacokinetic study in rabbits by high-pressure liquid chromatography].

A high-pressure liquid chromatographic method was developed for determination of m-nifedipine in plasma using a chemical bonded C-18 phase column (YWG-C18 10 microns, made in China) with nitrendipine as internal standard. To increase life of the YWG-C18 column a mixture of methanol and 5 mmol.L-1 phosphate buffer (70:30 vol/vol) was selected as mobile phase with a flow rate of 0.8 ml.min-1. The method was sensitive to m-nifedipine 3 ng.ml-1 plasma and the standard curve was linear from 10 to 1000 ng.ml-1 with correlation coefficient of 0.99. The within-day and day-to-day precisions (CV) of this method were 4.5% and 7.0%, respectively, with recoveries of 95-102% (10-1000 ng.ml-1). There was no interference with nifedipine, amiodarone, propranol, and verapamil. A pharmacokinetic study on m-nifedipine was carried out in 8 rabbits. A better computer fitted to a two-compartment model was observed using 3P87 program. The parameters obtained were as follow: Vc 6.3 L.kg-1, Cl 0.021 L.kg-1.min-1, T1/2 alpha 30 min, T1/2 beta 230 min, AUC 102 micrograms.min.ml-1.

Animals↗
PubMed1991

Expression of a full-length nonstructural protein NS1 of bluetongue virus serotype 17 in Escherichia coli.

The relative abundance of the nonstructural protein NS1 in bluetongue virus (BTV)-infected cells, the existence of NS1 in the BTV particles and the highly conserved NS1 gene among BTV serotypes indicate the diagnostic potential of using NS1 in detecting BTV infections. In this study a NS1 gene was expressed with the T7 RNA polymerase expression system to produce a full-length NS1 protein. Sheep anti-NS1 antibodies were raised with the E. coli-produced NS1 and used to show that the NS1 proteins of the five BTV serotypes in the Unites States were immunologically indistinguishable.

Animals↗
PubMed1991

Development of a novel Bacillus subtilis cloning system employing its neutral protease as screen marker.

Part of the pUC19 polylinker sequence (33 bp) was inserted into the pro-peptide-coding region of the Bacillus subtilis neutral protease-encoding gene to replace a 93-bp FspI-HindIII fragment. This in-frame sequence replacement had little effect on the expression and secretion of the neutral protease. This plasmid can therefore be used as a cloning vector, and recombinant clones can be directly identified on skim milk indicator plates by the loss of a clear ring (or halo) around the colonies. This novel cloning system offers several advantages over existing B. subtilis cloning vectors: (i) convenient direct screening of recombinants; (ii) the use of inexpensive indicator; (iii) no restriction on the use of host strains; and (iv) the availability of seven frequently used unique cloning sites: BamHI, XbaI, SalI, PstI, SphI, HindIII, and EcoRI. This system also has the potential to be used as an expression/secretion vector.

Amino Acid Sequence↗
PubMed1991

[Study on T-lymphocyte culture and function of T-lymphocyte subsets in patients with aplastic anemia].

T-lymphocytes form the peripheral blood of 12 patients with aplastic anemia (AA) and 4 patients with aplastic anaemia-paroxysmal hemoglobinuria syndrome (AA-PNH) were cultivated and their subsets were measured by monoclonal antibodies CD4, CD8, CD25 with indirect immunofluorescence technique. Change of the proportion of T-lymphocyte subsets was observed in 5 patients with AA after the mononuclear cells were activated with phytohemagglutinin (PHA). Its was shown that the number of CFU-T of the patients with AA was apparently decreased in comparison with that of normal controls (P less than 0.05). Disorder of T-lymphocyte subsets took place in patients with AA. The percentages of CD8 and CD25 lymphocytes were increased. The helper: suppressor T-lymphocytes (CD4:CD8) ratio was significantly increased (P less than 0.01). In the cases of AA-PNH, the number of CFU-T was significantly increased (P less than 0.01) and that of T-lymphocyte subsets did not change. The ratio of CD4/CD8 in 5 patients with AA was further decreased after activating mononuclear cells with PHA. These results showed that the increase of T-lymphocytes in patients with AA may account for the low level of CFU-T; the high level of CFU-T in patients with AA-PNH may be related to the multiplication of bone marrow cells. However, there may be a potential disorder of immune system on patients with AA at the same time.

Adolescent↗
PubMed1991

[A screening survey of variant glycophorins on the erythrocyte membranes among healthy chinese young people].

A screening survey of variant glycophorins (GP) on the erythrocyte membranes was conducted among 114 healthy Chinese young people who belong to several different ethnic groups by immunoblotting techniques. The majority (70) were of the Han ethnic group; 24 out of 41 Hainanese belonged to the Li ethnic group. Ten subjects showed variant GP profiles, with an incidence of 8.8%. The frequency of variants was significantly higher in the Li ethnic group (25%) than in the Han ethnic group (5.7%); none was seen among the other ethnic minorities. Probing with four antibodies specific to different regions of GP molecules revealed three distinct types of GP among the variant individuals. Type I observed in four individuals was reminiscent of that exhibited by Sta glycophorin. Among them, in one subject the Sta blood group phenotype was confirmed by serological typing. The absence of delta GP was noted in another subject carrying type II variant GP. Patterns in the remaining five individuals (type III) could not be correlated with known GP profiles of variants of MNSs blood system. This study suggests that there may be a high incidence of GP variants among certain ethnic groups in China. The sialic acid contents of erythrocyte membranes in seven GP propositi were significantly higher than those of the control.

Adolescent↗
PubMed1990

Site directed mutagenesis of subunit 8 of yeast mitochondrial ATP synthase. Functional and import properties of a series of C-terminally truncated forms.

The function of the positively charged C-terminal region of mitochondrially encoded subunit 8 of yeast mitochondrial ATP synthase was investigated using derivatives truncated at each of the 3 positively charged residues (Arg37, Arg42 and Lys47). Each construct, allotopically expressed in the nucleus, was tested for its ability to import and assemble functionally into ATP synthase in yeast cells unable to synthesize mitochondrial subunit 8. The efficiency of import of each construct into isolated wild-type yeast mitochondria was also determined. One construct truncated at the penultimate residue of subunit 8 (Lys47) functions in vivo and shows efficient import in vitro. Thus subunit 8 can function with only two positively charged residues. The remainder of the subunit 8 variants failed to rescue in vivo. Since they all show greatly reduced or undetectable import in vitro, presumably because of the increased hydrophobic character of the subunit 8 moiety in the chimaeric precursors, the status of these variants as regards assembly and function is not clear.

Base Sequence↗
PubMed1990

Expression of a sperm protein gene during spermatogenesis in mammalian testis: an in situ hybridization study.

In previous work a specific membrane protein with an estimated Mr of 20.1 kDa was purified from rabbit sperm tails and designated as rSMP-B protein. Antibodies were raised against rSMP-B protein and used to isolate and identify the cDNA coding the rSMP-B protein from a rat testis lambda gt11 expression library. The nucleotide sequence of the cDNA was determined in a previous study. Single-stranded 35S-labeled RNA probes were prepared. With the techniques of in situ hybridization, rSMP-B mRNA was detected in spermatids of rat and rabbit testis. The present results support our previous observation that immunization of male rabbits with the rSMP-B protein results in the arrest of spermatogenesis at the spermatid stage. Overall, rSMP-B protein appears to be involved in spermiogenesis, and the synthesis of the mRNA encoding the protein occurs in germ cells during the postmeiotic haploid phase of spermatogenesis.

Animals↗
PubMed1990

Characterization of cDNA encoding a human sperm membrane protein related to A4 amyloid protein.

A rat testis lambda gt11 cDNA library was screened with a monoclonal antibody raised against a human sperm membrane protein designated YWK-II. A clone was found with a cDNA insert composed of 1837 base pairs that contained an open reading frame coding for 191 amino acid residues. The deduced polypeptide contained a segment with high homology to the transmembrane-cytoplasmic domains of the A4 amyloid protein found in brain plaques of Alzheimer disease patients. A sequence of basic amino acid residues, Arg-Lys-Arg, was found instead of Lys-Lys-Lys at the probable membrane-cytoplasmic junction that may be a unique property of sperm membrane proteins.

Amino Acid Sequence↗
PubMed1990

A seral epidemiological study of HIV transmitted through human seral gamma-globulin preparations.

In order to study the potential risk of transferring HIV through human seral gamma-globulin preparations (immunoglobulin), indirect immunofluorescent antibody test (IFA) and Western Blot (WB) assay were applied to 343 random samples (sera) with previous injection of imported human seral gamma-globulins (Ig) positive for Human Immunodeficiency Virus (HIV) antibodies between 1981-1987 for the detection of HIV antibodies. All results were negative and tests on all 23 controls who had previously received Ig made in China also gave negative results. However all 12 batches of imported Ig collected from the above-mentioned users, were positive for HIV antibodies when tested by WB and IFA. This study shows that under normal conditions, human seral gamma-globulin does not transmit HIV.

Adolescent↗