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Biomedical subjects

L Sun

Publications and source records attributed to L Sun.

At least 469 records · Page 26Linked to original sources
PubMed1993

Analysis of respiratory syncytial virus genetic variability with amplified cDNAs.

Antigenic and genetic heterogeneities exist within the two major antigenic groups of respiratory syncytial (RS) virus. We developed a polymerase chain reaction (PCR)-based assay that not only differentiates the two RS virus groups but allows distinctions within groups on the basis of changes in the nucleotide sequences, as revealed by restriction fragment analysis. In this assay, viral RNA served as a template for cDNA synthesis with extension from a synthetic oligonucleotide primer complementary to bases 164 to 186 in the F protein mRNA. For PCR amplification, two group-specific 5' primers were added. The two primers corresponded to the G protein mRNA sequence of group B (bases 10 to 30) or group A (bases 247 to 267) RS virus. Agarose gel electrophoresis readily discriminated the 1.1-kb group B and the 0.9-kb group A virus amplification products. All 47 viruses tested were assigned to the same group by both PCR and monoclonal antibody reaction pattern analysis. Restriction fragment analysis of the amplified DNAs revealed 12 restriction patterns for group A viruses and 7 restriction patterns for group B viruses, while the monoclonal antibody reaction patterns revealed seven patterns for group A viruses and 3 patterns for group B viruses. Most viruses with the same monoclonal antibody reaction patterns had different restriction patterns, and some viruses with the same restriction patterns had different monoclonal antibody reaction patterns. Thus, the results of the PCR assay concurred with the monoclonal antibody reaction pattern analysis for group classification of RS viruses, while the restriction fragment analysis identified greater diversity within groups than was seen with the monoclonal antibody analysis.

Antigens, Viral↗
PubMed1993

Cosegregation of the renin gene with an increase in mean arterial blood pressure in the F2 rats of SHR-WKY cross.

Using the restriction endonuclease, Bgl I, Samani et al. found a restriction fragment length polymorphism (RFLP) for the renin gene in spontaneously hypertensive rats (SHR) and its normotensive control Wistar-Kyoto (WKY) rats (1). This RFLP was confirmed in our laboratory in SHR and WKY rats using a rat renin cDNA probe. The correlation of blood pressure and the renin RFLP was examined in 106 F2 rats produced from F1 rats, the offspring of a cross between SHR males and WKY females. Systolic blood pressure was measured by the tail cuff method at 12 weeks of age. Mean arterial blood pressure of anesthetized rats was measured by cannulation of the femoral artery prior to sacrifice. The frequency of renin genotype showed a typical 1:2:1 Mendelian ratio in F2 rats of SHR and WKY cross. The mean arterial blood pressure of F2 rats homozygous with the SHR allele was significantly higher than F2 rats that were heterozygous or homozygous for the WKY allele. No significant difference in systolic blood pressure was observed in F2 rats with different genotypes. Thus, the renin gene RFLP cosegregates with an increase in mean arterial blood pressure in the F2 rats of SHR and WKY cross.

Alleles↗
PubMed1993

Structure-function studies of the C-terminal alpha-helix of human interleukin-2 by site-directed mutagenesis.

By using oligonucleotide-mediated site-directed mutagenesis, we obtained three human interleukin-2 analogs with substitution of Pro in the C-terminal amphiphilic alpha-helix, 125Pro-IL-2, 127Pro-IL-2 and 125Pro-127Pro-IL-2. The bioactivities of all these analogs were decreased. The extent of the decrease in bioactivity coincided with the degrees of secondary and tertiary structure destroyed, as evaluated by circular dichroism and intrinsic fluorescence analysis. The results suggested that the integrity of the hydrophobic face in the C terminal alpha-helix is crucial for the structure and function of interleukin-2.

Base Sequence↗
PubMed1993

Effect of acupuncture and point-injection treatment on immunologic function in rheumatoid arthritis.

The results of treatment of 54 cases of rheumatoid arthritis (RA) by warm needling (WN) and point-injection (PI) with Zhuifengsu are reported. Good clinical results were observed with an effective rate of 100%. At the same time, changes in cellular and humoral immunity and other parameters in peripheral blood were noted before and after treatment. The NK activity and IL-2 value in RA patients were found to be lower than those of normal individuals; both increased after treatment (P < 0.01). This suggests that the WN and PI with Zhuifengsu exert a regulatory effect on the cellular immunological function.

Acupuncture Points↗
PubMed1993

C3 synthesis by A549 alveolar epithelial cells is increased by interferon-gamma and dexamethasone.

The third component of complement, C3, is produced in the lung by several cell types including alveolar epithelial cells. Since interferon-gamma (IFN-gamma) and dexamethasone regulate C3 gene expression in non-pulmonary cells, and because IFN-gamma and dexamethasone interact to regulate the functional activity of alveolar epithelial cells, we investigated the effects of IFN-gamma and dexamethasone on C3 production by A549 human alveolar epithelial cells. Treatment of A549 cells with IFN-gamma alone increased C3 production in a time-and dose-dependent manner. Maximal increase in C3 production occurred after stimulation of A549 cells with 500 IU/ml IFN-gamma for 3 days and was 3.4-fold greater than control. Dexamethasone (0.1 microM) stimulation of A549 cells increased C3 production 6.7-fold over controls on day 3. Treatment of A549 cells with IFN-gamma plus dexamethasone resulted in an 11-to 13-fold increase in C3 synthesis. C3 mRNA levels were increased in A549 cells treated with IFN-gamma and dexamethasone individually and in combination suggesting that IFN-gamma and dexamethasone increase C3 synthesis by a pre-translational mechanism. IFN-gamma and dexamethasone did not alter the two-chain structure of the C3 molecule produced by A549 cells, as assessed by Western blotting. We speculate that IFN-gamma and glucocorticoids may be important in the local regulation of C3 synthesis in the lung.

Blotting, Northern↗
PubMed1993

Development and longevity of Nosopsyllus laeviceps kuzenkovi (Siphonaptera) from Inner Mongolia under laboratory conditions.

The development and longevity of Nosopsyllus laeviceps kuzenkovi (Yagubyants), a major plague vector among sylvan and campestral rodents in Inner Mongolia, China, was studied under controlled laboratory conditions of 11, 14, 17, 20, 23, 26, 29, and 35 C at 76% relative humidity (R.H.), and 32, 53, 76, 87, and 100% at 23 C. Development from egg to adult was shortest (21-23 days) under favorable conditions of 26 C at 76% R.H., but maximum survival to adulthood (84%) occurred at 23 C. Average longevity was 13.25 days (13.70 in females and 12.80 in males) at 17 C and 76% R.H.; it was longer at cooler and shorter at warmer temperatures. Findings provided experimental data that helped clarify seasonal fluctuations, summer mortality, generation cycles, and survival of compared flea species from Russia, Azerbaidzhan, and China.

Animals↗
PubMed1992

Northern blot and ribonuclease protection study of alpha 2-adrenoceptor subtypes in cultured cell lines.

Northern blot and ribonuclease protection assay were used to identify alpha 2-adrenoceptor subtypes in human colonic adenocarcinoma (HT29), neuroblastoma x glioma rat-mouse hybrid NG108-15 (NG108) and opossum kidney (OK) cell lines. Radioligand binding studies showed that the alpha 2-adrenoceptor expressed in HT29, NG108 and OK cells represent the pharmacological alpha 2A, alpha 2B and alpha 2C subtypes respectively. In our Northern blot analysis, hybridization of poly(A)+ RNA from HT29, NG108 and OK cells with human kidney alpha 2-adrenoceptor cDNA probe (alpha 2-C4) identified a single band of 4.4, 4.2 and 4.4 kb respectively in each cell line. Hybridization with a human platelet alpha 2-adrenoceptor genomic probe (alpha 2-C10) resulted in two bands for HT29 cells with the size of 4.4 kb and 3.9 kb. No bands were seen for HT29, NG108 and OK cells when hybridized with a third alpha 2-adrenoceptor human genomic DNA probe which is localized in chromosome 2 (alpha 2-C2). For the HT29 cells, the 3.9 kb band was seen only when using the alpha 2-C10 probe. Thus, this band probably represents alpha 2-C10 mRNA. To further characterize the alpha 2-adrenoceptor mRNA expressed in HT29, NG108 and OK cells, the sensitive ribonuclease protection assay was performed. A single band about 900 bp was protected when the poly(A)+ RNA from NG108 and OK cells was hybridized with an alpha 2-C4 RNA probe and digested with RNAases. Hybridization of mRNA from HT29 cells with alpha 2-C10 RNA probe and digestion with RNAases protected a 500 bp fragment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Chromosome analysis in spontaneous pregnancy loss: use of placental villus mesodermal core cell cultures.

Culture of placental villus mesodermal core cells, a method developed for chorionic villus sampling, was used for cytogenetic analysis in 168 spontaneous pregnancy losses. Successful karyotype results were obtained in 72% of cases and 87.5% of cases in which placental tissue was available. Culture of placental villus mesodermal core cells is useful in the evaluation of spontaneous pregnancy loss, particularly when tissues of direct fetal origin are unavailable or unsuitable for culture. Details of culture and specimen handling techniques are provided.

Abortion, Spontaneous↗
PubMed1992

Study of mechanisms of electric field-induced DNA transfection. IV. Effects of DNA topology on cell uptake and transfection efficiency.

Electric parameters and solvent conditions are known to influence the efficiency of DNA transfection of cells by a pulsed electric field (PEF). A previous study (Neumann, E., M. Schaefer-Ridder, Y. Wang, and P. H. Hofschneider. 1982. EMBO (Eur. Mol. Biol. Organ.) J. 1:841-845) has indicated that DNA topology is also an important determinant. We report an investigation of the PEF induced uptake, stability, and expression of three different topological isomers, circular supercoiled (scDNA), circular relaxed (crDNA), and linearized (lnDNA) forms of the plasmid pBR322, by Escherichia coli strain JM105. Monomeric pBR322 prepared by the electroelution from an agarose gel was in the supercoiled form. Treatment of the scDNA with wheat germ topoisomerase I removed the superhelicity and the DNA assumed the relaxed circular form. Treatment of scDNA by a restriction endonuclease, EcoRI or Hind III, linearized the DNA. The MgCl2-dependent bindings of all three forms of DNA to the cell surface were indistinguishable. So was the PEF induced cell uptake. In contrast, the transfection efficiency (TE) for the scDNA and the crDNA were high (approximately 2 x 10(8) micrograms-1 DNA at neutral pH), whereas that for the lnDNA was approximately five orders of magnitude lower (less than 1 x 10(3) micrograms-1 DNA). Analysis by agarose gel electrophoresis indicated that the PEF loaded ln DNA was degraded by the host cell within 3 h. However, the loaded scDNA and the crDNA were stable and expressed in the cytoplasm. We conclude that first, the PEF induced DNA entry into E. coli did not depend on the topology of the DNA. As cellular uptake of DNA also correlated with the surface binding, these data support electrophoresis of surface bound DNA as the dominating mechanism for the DNA entry. Second, the variations of TE for different topological forms of DNA reflected their relative stability in the host cells. Third, since the loaded DNA could be either rapidly degraded by the host enzyme or expressed, they were unlikely coated with a layer of protective lipid membrane. Thus, PEF induced cellular uptake of DNA is unlikely by the endocytotic mechanisms as was reported previously for the liposomes (Chernomordik, L. V., A. V. Sokolov, and V. G. Budker. 1990.Biochim. Biophys. Acta. 1024:179-183).

Ampicillin Resistance↗
PubMed1992

Escherichia coli ribonucleotide reductase expression is cell cycle regulated.

The expression of the genes encoding ribonucleotide reductase in Escherichia coli was investigated in cultures synchronized by obtaining the smallest cells in a population after sucrose gradient centrifugation. Specific activity of ribonucleotide reductase and DNA initiation were found to increase in parallel, periodically as a function of the cell cycle. The expression of nrd was also determined in cells synchronized by periodic repeated doubling in a phosphate limited medium. Antibodies directed against the B2 subunit of ribonucleotide reductase were raised in a rabbit and purified. Immunoprecipitation of the B2 subunit and RNA-DNA dot blot hybridization assays were developed and employed to determine the expression of ribonucleotide reductase translational and transcriptional products during the cell cycle. Both of nrd-mRNA and B2 subunit expression were found to increase each generation at approximately the same time DNA synthesis was initiated and then to decrease back to the basal level shortly after DNA initiation. These results provided evidence of cell cycle dependent regulation of ribonucleotide reductase in E. coli. When the upstream regulatory region of nrd was fused to a promoterless lacZ gene on a single copy plasmid, lac-mRNA and beta-galactosidase were found to be synthesized in parallel to nrd expression from the chromosomal operon. When nrd sequences surrounding the promoter were removed from this construct, lac-mRNA and beta-galactosidase synthesis were no longer cell cycle regulated.

Cell Cycle↗
PubMed1992

Establishment of large cell lung cancer cell lines secreting hematopoietic factors inducing leukocytosis and thrombocytosis.

We have established cell lines from a large cell carcinoma of the lung accompanied by marked granulocytosis and thrombocytosis, and have analyzed the factors with colony stimulating factor (CSF) activity produced by them. Analysis of the CSF activity present in the culture medium of the established cell lines demonstrated growth-stimulating activity on CMK cells, a human megakaryoblastic cell line and mouse bone marrow cells. A neutralization test with antibodies against G-, M- and GM-CSF indicated the stimulation for the proliferation of CMK and mouse bone marrow cells to be mediated partially by the CSFs. Furthermore, the measurement of GM-CSF and interleukin(IL)6 by enzyme-linked immunosorbent assay (ELISA) and northern blotting analysis indicated productions of G-, GM- and M-CSF and of IL6 from the cell lines but failed to exhibit IL3 gene expression. It is suggested that the cell lines could be of use in the study of CSFs and, also, that lymphokines act on leukocyte and platelet progenitor cells.

Adult↗
PubMed1992

[Experimental study on the influence of acupuncture and moxibustion on interleukin-2 in patients with rheumatoid arthritis].

Rheumatoid arthritis (RA) is referred to the category of Bi syndromes in traditional Chinese medicine. It is regarded as an autoimmune disease, but the pathogenic mechanism is still to be clarified. In order to observe the effects of the treatment of RA with acupuncture and moxibustion on IL-2, 41 patients were divided into warming needle and point injection groups at random, and 19 healthy subjects as control group. The results showed that the IL-2 levels in two RA groups before treatment were obviously lower than that in control group (P 0.05). After treatment the IL-2 level in control group was unchanged, but increased considerably in two RA groups (P 0.01). Generally, IL-2 is considered as a very important signal for regulating immune response. Our results have shown that the decrease of IL-2 in patients with RA should be one of main causes of internal environment disorder, acupuncture and moxibustion as a stress stimulation exerts an influence on the immunity system through neuroendocrine system to improve the IL-2 production.

Acupuncture Therapy↗
PubMed1992

The frequency of alpha 2-adrenoceptor restriction fragment length polymorphisms in normotensive and hypertensive humans.

OBJECTIVE: To examine the frequency of distribution of allelic polymorphisms of the alpha 2-adrenoceptor gene in normotensive and hypertensive humans. DESIGN: The frequency of alpha 2-adrenoceptor genotypes was compared in the two groups using the chi 2-test. SETTING: The Midwest Hypertension Research Center Outpatient Clinic of Creighton University School of Medicine. STUDY PARTICIPANTS: History was taken from and physical examination performed on each of the 60 hypertensive and 47 normotensive adults. METHODS: DNA was extracted from leukocytes from each participants. Twenty restriction endonucleases were used and one restriction fragment length polymorphism (RFLP) was found using a 950-bp restriction fragment from the coding region of the human platelet alpha 2-adrenoceptor gene (ADRA2R) and Bsu36I restriction endonuclease. This probe and Bsu36I restriction endonuclease, in addition to another restriction endonuclease (Dra I), were then used in the study. RESULTS: Three genotype patterns were found. Homozygotes for the Bsu36I RFLP have either a unique 12-kb or a unique 5.8-kb band. Heterozygotes have both bands. The frequency of this alpha 2-adrenoceptor RFLP was calculated. In hypertensives the frequencies of the 12- and 5.8-kb alleles were 0.52 and 0.48, compared with 0.45 and 0.55, respectively, in normotensive, a difference that was not statistically significant. CONCLUSIONS: The frequency of the Bsu36I RFLP involving an alpha 2-adrenoceptor gene in hypertensives did not differ significantly from that in normotensives. A genetic linkage study is now under way to test for an association of the Bsu36I RFLP of the alpha 2-adrenoceptor gene with essential hypertension in families.

Adult↗
PubMed1992

Stimulation of prostaglandin production in rat thymic epithelial cells by protein kinase C mediated activation of phospholipase A2.

Tumor promoter (phorbol-12-myristate-13-acetate:PMA) stimulates the production of prostaglandin E2 (PGE2) in a dose- and time-dependent manner in cloned rat thymic epithelial cells, TEA3A1. This stimulation of PGE2 production by PMA was blocked by pretreatment of cells with protein kinase C (PKC) inhibitor staurosporin and was abolished in PKC down modulated cells. PMA treatment significantly stimulated the release of arachidonic acid from the cells, but had no effect on arachidonic acid incorporation and on cyclooxygenase enzymatic activity of the cells. These results indicate that PMA stimulates PGE2 production through PKC mediated activation of phospholipase A2 (PLA2) in thymic epithelial cells.

Animals↗
PubMed1991

Sex chromosome marker: clinical significance and DNA characterization.

Two patients are described with a virtually identical marker sex chromosome that was so small as to defy classification by conventional cytogenetic studies. DNA hybridization with Y probes allows classification into Y or non-Y, and in situ hybridization with X centromere specific sequences, into X or non-X. One patient was proven to have a Y fragment, and the second, an X fragment. DNA characterization is important since prognosis and clinical management depends on proper identification of the small marker sex chromosome.

Child, Preschool↗