Biomedical subjects

N Yang

Publications and source records attributed to N Yang.

At least 109 records · Page 6Linked to original sources

PubMed1996

De Novo renal expression of macrophage migration inhibitory factor during the development of rat crescentic glomerulonephritis.

Macrophage migration inhibitory factor (MIF), a key mediator of the delayed-type hypersensitivity response, was originally thought to be produced by activated T cells. However, recent studies have found that MIF is produced in many cell types including monocytes/macrophages and anterior pituitary cells. The current study has examined MIF expression in normal and diseased kidney using in situ hybridization, immunohistochemistry, and Northern blotting. MIF mRNA and protein are constitutively expressed in normal kidney, being largely restricted to tubular epithelial cells and some glomerular visceral and parietal epithelial cells. During the development of rat anti-glomerular basement membrane glomerulonephritis, a model of macrophage-mediated renal injury, there was marked de novo expression of MIF by intrinsic kidney cells including endothelium and glomerular and tubular epithelial cells. Up-regulation of MIF expression correlated with macrophage accumulation within the glomerulus (P < 0.001) and tubulointerstitium (P < 0.001). Of significance, the accumulation of macrophages was exclusively localized to areas of strong MIF expression, contributing to focal glomerular and tubulointerstitial lesion formation. In addition, up-regulation of MIF expression by parietal epithelial cells was associated with macrophage accumulation within Bowman's space and crescent formation. Combined in situ hybridization and immunostaining also demonstrated MIF expression by macrophages, T cells, and fibroblast-like cells within renal lesions. In conclusion, these data provide the first demonstration that renal epithelial cells are a major source of MIF in both normal and diseased kidney. Furthermore, the up-regulation of MIF expression may play an important role in macrophage accumulation and progressive renal injury in rat crescentic glomerulonephritis.

Animals↗

PubMed1996

[Construction of gene library of attenuated liver hepatitis A vaccine (H2 strain)].

OBJECTIVE: To determine the complete gene library of attenuated live hepatitis A vaccine (H2 strain) from cloned cDNA by application of reverse transcription (RT) and polymerase chain reaction (PCR) technique. METHODS: Attenuated HAV H2 strain that was selected and studied in China was proven attenuated for human beings and proved to be effective in preventing hepatitis A. RESULTS: Ten overlapping cDNA clones were obtained in addition to spanned the entire genome. The restriction enzyme mapping was also determined. CONCLUSION: The gene library will benefit for the sequence of HAV cDNA and study on attenuation.

DNA, Viral↗

PubMed1996

[Percutaneous transluminal angioplasty for the treatment of occlusion of proximal subclavian artery].

Percutaneous transluminal angioplasty (PTA) is a well-established treatment for patients with stenosis of limb arteries. However, its efficacy for treatment of severe stenosis and occlusions of the subclavian artery is unclear. We attempted to recanalize the subclavian artery in 30 patients with severe stenosis or total occlusion of proximal subclavian artery and successful outcomes were seen in 27 cases (90%). In two patients the regional arterial thrombolysis with the PTA prcedure we used was found successful. There was no severe complications. During an average 6-month follow-up stenosis recurred in 2 patients, but the subclavian artery was recanalized by repedted PTA.

Adult↗

PubMed1996

[Management of coagulation dysfunction in critically surgical patient].

12 surgical critically ill patients were studied for a better management of perioperative coagulation dysfunction. Their primary disease, clinical manifestation as well as some coagulation tests before and after therapy were retrospectively analysed. The result showed that secondary disseminated intravascular coagulation (DIC) is the main type of perioperative coagulation disorder, especially in decompensated hepatopathy and severe sepsis patients. It should be emphasized that: control of primary disease, effective drainage of focus, strict indication for 2nd surgical hemostasis and correct operation are required. For those hepatopathy with hypofibrinogenemia, some hemostatic drugs should be prohibited or very carefully used, in order to avoid the activation of plasmin and the exhaustion of fibrin. The early administration of heparin and aprotinin after the supplement of fibrinogen has shown a great potential benifit to stop the cascade of hypercoagulation and hyperplasminogenemia by enhancing the level of AT-III and fibrinogen in plasma.

Adult↗

PubMed1995

Regulation of vascular smooth muscle growth by alpha 1-adrenoreceptor subtypes in vitro and in situ.

Rat aorta smooth muscle cells which express all three alpha 1-adrenoreceptors (alpha 1A, alpha 1B and alpha 1D) were used to determine the effect of stimulation of alpha 1-adrenergic receptor subtypes on cell growth. "Combined" alpha 1-adrenoreceptor subtype stimulation with norepinephrine alone caused a concentration-dependent, prazosin-sensitive increase in protein content and synthesis: 48 h of stimulation at 1 microM increased cell protein to 216 +/- 40% of time-matched controls (p = 0.008) and RNA to 140 +/- 13% (p = 0.03); protein synthesis increased to 167 +/- 13% (p < 0.01) after 24 h. Stimulation with norepinephrine plus the selective alpha 1A/alpha 1D antagonist 5-methylurapidil produced greater increases in alpha-actin mRNA (270 +/- 40% at 8 h; p = 0.007), total cell protein (220 +/- 45% at 24 h; p = 0.004), and RNA (135 +/- 8% at 24 h; p = 0.01). These effects were prevented by pretreatment with the selective alpha 1B antagonist chloroethylclonidine. Comparable results were obtained for intact aortae. Stimulation with norepinephrine plus 5-methylurapidil increased (p < 0.05) tissue protein, RNA, dry weight, and alpha-actin mRNA; and as in culture cells, combined stimulation with norepinephrine alone attenuated these responses. By comparison, adventitia (fibroblasts) was unaffected. Removal of endothelial cells had no effect. alpha 1B mRNA decreased by 42 +/- 12% (p = 0.01) in cultured cells during combined alpha 1-adrenoreceptor stimulation and by 23 +/- 8% (p = 0.03) for intact aorta. alpha 1D and beta-actin mRNA were unchanged in cultured cells, aorta media, and adventitia. These findings suggest that prolonged stimulation of chloroethylclonidine-sensitive, possibly alpha 1B-adrenoceptors induces hypertrophy of arterial smooth muscle cells and that stimulation of 5-methylurapidil-sensitive, non-alpha 1B-adrenoreceptors attenuates this growth response.

Actins↗

PubMed1995

Molecular cloning of the gene encoding RecF, a DNA repair enzyme, from Streptococcus pyogenes.

RecF is a component of one of the bacterial DNA repair systems. The start codon of the recF gene of Streptococcus pyogenes resides about 4.4 kb downstream from the end of hasA, the hyaluronan synthase-encoding gene, which is transcribed in the opposite orientation. The deduced 368-amino-acid RecF protein is 43.5% identical to its homolog from Bacillus subtilis. When cloned on a plasmid, recF could complement a S. pyogenes deletion mutant that was sensitive to ultraviolet irradiation and chemical mutagens. This is the first report of a recF sequence from a Gram+ pathogen.

Amino Acid Sequence↗

PubMed1995

Evidence for voltage-dependent S4 movement in sodium channels.

The mutation R1448C substitutes a cysteine for the outermost arginine in the fourth transmembrane segment (S4) of domain 4 in skeletal muscle sodium channels. We tested the accessibility of this cysteine residue to hydrophilic methanethiosulfonate reagents applied to the extracellular surface of cells expressing these mutant channels. The reagents irreversibly increase the rate of inactivation of R1448C, but not wild-type, channels. Cysteine modification is voltage dependent, as if depolarization extends this residue into the extracellular space. The rate of cysteine modification increases with depolarization and has the voltage dependence and kinetics expected for the movement of a voltage sensor controlling channel gating.

Adult↗

PubMed1995

[Chemotherapy through selective pelvic artery catheterization complicated by mural thrombosis].

Through catheter on uterine artery digital subtractive angiography (DSA) intraarterial infusion of chemotherapeutic agents for the treatment of malignant trophoblastic diseases can raise local drug concentration, improve therapeutic results and reduce general side-effects. But mural thrombosis, a possible complication of intra arterial catheterization, should not be overlooked. This study reports 2 cases of mural thrombosis complication in selective pelvic artery catheterization for chemotherapy. The incidence, relevant factors to its occurrence such as technique of catheterization and the duration of catheter retention, as well as measures of prevention and treatment of mural thrombosis are discussed together with review of literature. With regards to prevention of mural thrombosis, stress is being laid on the importance of the technique of catheterization. Preliminary comments on the problem of heparin administration as a preventive measure of mural thrombosis are made.

Adult↗

PubMed1994

Sodium channel mutations in paramyotonia congenita exhibit similar biophysical phenotypes in vitro.

Mutations in the skeletal muscle voltage-gated Na+ channel alpha-subunit have been found in patients with two distinct hereditary disorders of sarcolemmal excitation: hyperkalemic periodic paralysis (HYPP) and paramyotonia congenita (PC). Six of these mutations have been functionally expressed in a heterologous cell line (tsA201 cells) using the recombinant human skeletal muscle Na+ channel alpha-subunit cDNA hSkM1. PC mutants from diverse locations in this subunit (T1313M, L1433R, R1448H, R1448C, A1156T) all exhibit a similar disturbance in channel inactivation characterized by reduced macroscopic rate, accelerated recovery, and altered voltage dependence. PC mutants had no significant abnormality in activation. In contrast, one HYPP mutation studied (T704M) has a normal inactivation rate but exhibits shifts in the midpoints of steady-state activation and inactivation along the voltage axis. These findings help to explain the phenotypic differences between HYPP and PC at the molecular and biophysical level and contribute to our understanding of Na+ channel structure and function.

Base Sequence↗

PubMed1994

The Streptococcus pyogenes hyaluronan synthase: sequence comparison and conservation among various group A strains.

We recently cloned the hyaluronan synthase gene (hasA) from Streptococcus pyogenes (DeAngelis et al., J. Biol. Chem. 268, 19181, 1993). Since this is the first glycosaminoglycan synthase gene to be cloned and these enzymes have also not been purified, nothing is yet known at the molecular level about the similarity or relatedness of hyaluronan synthase to other gene products. We found several proteins in the sequence database with substantial similarities to hyaluronan synthase (HasA), including NodC from Rhizobium, DG42 from Xenopus, and the three chitin synthases (Chs) from Saccharomyces. Like HasA, NodC and the Chs proteins all have at least an N-acetylglucosaminyl transferase activity in common and are membrane-associated. The polymerase chain reaction was also used to show that HasA, and probably the two gene operon for hyaluronan biosynthesis (hasA/hasB), is highly conserved among Group A streptococcal strains. In nine strains, isolated from 1917 through 1993, only five silent mutations were detected. The results show that hyaluronan synthase is highly conserved within Group A strains, although another virulence factor, the M protein, varies considerably in these same strains.

Amino Acid Sequence↗

PubMed1994

Transcription function of each base pair in the control region of the adenovirus VARNA1 gene.

Eighty-seven mutants with single-base substitution in the control region (from -44 to +70) of the adenovirus VARNA1 gene were generated, including nearly every base pair, to examine the role of DNA sequences within this control region for regulating transcription. The effect of these mutations on transcription of the gene was determined in vitro using cytoplasmic S100 extracts from human KB cells. Mutations at -37T, -35A, -29T, -28A, -25C, -18A, -17A, -16A, -13A, -9C, -8C, and -1C in the 5'-flanking region reduced transcription of the gene. Thus two positive regulatory elements, from -44 to -25 and from -18 to +2, interspersed with a putative negative regulatory element were defined. Furthermore, a distinct A-rich purine stretch in the -18 to +2 element was identified. Point mutations in the pyrimidine-rich sequence immediately upstream of the A block promoter element reduced transcription of the gene. Mutations in the GTGG direct repeats of the A block promoter element drastically decreased transcription. Furthermore, mutations that altered the AT-rich sequence immediately downstream of the A block element to become less AT-rich decreased transcription. Mutations of the base pairs at +43C, +45T, and +51A in the inter-block element moderately reduced transcription efficiency of the gene. Mutations at the central four base pairs, GTTC, of the B block palindrome severely affected transcription. These unique sequence motifs and their exact base pairs were proven to be important for regulating transcription of the VARNA1 gene.

Adenoviruses, Human↗

PubMed1994

Glyceryl-ether monooxygenase (EC 1.14.16.5): nature of the glyceryl-ether lipid substrates in aqueous buffer.

The kinetics of inhibition of glyceryl-ether monooxygenase with 6-methyl-5,6,7,8-tetrahydropterin as cofactor (saturating) by the detergent Mega-10 with batyl alcohol and (RS)-3-(1-hexadecyloxy)-2-hydroxypropane-1-phosphocholine as substrates exhibited noncompetitive inhibition with apparent Ki values of 1.74 +/- 0.37 mM and 185 +/- 23 microM, respectively. Inhibition by octadecan-1-ol (with batyl alcohol as substrate in the presence of 2.3 mM Mega-10) was competitive with an apparent Ki value of 765 +/- 80 microM. The critical micelle concentration values of various solutions of Mega-10 were determined and used to show that the active ether-lipid substrates were in micelle form (for a water soluble substrate) or mixed micelle form (for substrates solubilised with Mega-10).

Animals↗

PubMed1994

[The effect of nutrition support and recombinant growth hormone on body composition and muscle function in postoperative patients].

To determine the effects of nutritional support and recombinant human growth hormone (GH) on body composition and muscle function, we performed a randomized double-blind trial in 18 patients after elective gastrectomy or colectomy. Same amount of calories and amino acids were administered. Daily injection of GH or placebo was given during the first postoperative week. The GH dose was 0.2 IU/kg/d. The study of body composition demonstrated that control subjects lost lean body mass and fat 2.8 +/- 1.46kg and 0.49 +/- 1.3kg, respectively. In contrast, study group subjects lost the fat 0.95 +/- 0.46kg. Hand grip strength fell with time in the control group (P < 0.05). In contrast, grip strength of GH-treated subjects was significantly different from controls (P < 0.01). The study results demonstrated that nutritional support and growth hormone can maintain lean body mass and muscle function in postoperative patients.

Adult↗

PubMed1993

Insertional editing in mitochondria of Physarum.

RNA produced from a number of genes on the mitochondrial (mt) DNA of Physarum polycephalum have nucleotides inserted at specific sites in their sequence. These insertions are spaced at approximately 25 nucleotide intervals and create open reading frames in mRNA and functional structure in tRNAs and rRNAs. Although most of the insertions at a site are single cytidines; single uridines and certain dinucleotides containing adenosine and guanosine as well as cytidine and uridine are also occasionally inserted at certain sites. This mixed nucleotide insertional RNA editing is unique among currently characterized editing systems.

Amino Acid Sequence↗

PubMed1993

COUP-TF acts as a competitive repressor for estrogen receptor-mediated activation of the mouse lactoferrin gene.

We previously demonstrated that the estrogen response module (mERM) of the mouse lactoferrin gene, which contains an overlapping chicken ovalbumin upstream promoter transcription factor (COUP-TF)- and estrogen receptor-binding element, is responsible for estrogen induction. In this report we show that COUP-TF represses the mERM response to estrogen stimulation. Mutation and deletion of the COUP-TF-binding element or reduction of the endogenous COUP-TF increases mERM estrogen responsiveness. Likewise, overexpression of the COUP-TF expression vector blocked the estrogen-stimulated response of mERM in transfected cells. The molecular mechanism of this repression is due to the competition between COUP-TF and the estrogen receptor for binding at identical contact sites in the overlapping region of the mERM. Our results indicate that two members of the steroid-thyroid receptor superfamily work in concert to modulate lactoferrin gene expression.

Animals↗

PubMed1993

[Unequal genetic contributions of parents to offsprings and their optimal control].

Due to the joint effects of natural and artificial selection, the proportions of genetic materials originating from different parents may vary in the gene pool of offsprings, and this creates a problem of unequal genetic contributions of parents to offsprings. It is shown that unequal genetic contribution substantially affects the genetic gain via realized selection differential and effective population size, and brings error to the empirical prediction formulae of selection response: R = i.sigma P.h2. The aim of breeding should be to select the genetically superior individuals and then to make more genetic contributions of better parents to offspring gene pool. However, the latter aspect has been ignored in theoretical study as well as in certain breeding practice. To deal with the problem, a method which takes maximizing genetic advance as general objective and considers some breeding restrictions, is suggested to control the percentage of genetic contributions. A numerical example from egg-type chicken breeding is used to demonstrate the effects of optimal control of unequal genetic contributions. The result indicates that at the same level of effective population size, the realized selection response for different traits under the optimal pattern of unequal genetic contributions could be 34.27-216.57% higher than that under the actual unequal pattern.

Animals↗

PubMed1993

The human ecology of tornadoes.

This paper offers an empirical test of the impact of human ecological patterns and other known correlates on tornado occurrence. It uses the National Severe Storms Forecast Center's information on tornadoes from 1950 through 1990 and employs ecological data from the U.S. Bureau of the Census and the Environmental Protection Agency. The results show that metropolitan and other urban counties have higher odds of tornado occurrence than rural counties, and that the probability of occurrence of tornadoes increases with increases in the number of previous tornadoes. The paper assesses the meaning of this finding for demographers, atmospheric scientists, engineers, and disaster managers.

Disasters↗

PubMed1992

Development of human ABO blood group A antigen on Escherichia coli Y1089 and Y1090.

Studies by other workers have shown that some strains of Escherichia coli have surface antigens analogous to the human blood group ABH antigens, and that these are carbohydrates associated with membrane lipopolysaccharides. This study has demonstrated that E. coli strains Y1089 and Y1090 possess the H antigen, which can be converted to the A antigen by incubation with A-transferase (N-acetyl-galactosaminyl transferase) and A-sugar (UDP-N-acetyl-galactosamine). Such cells will then form mixed agglutinates with human A red cells and human polyclonal (but not mouse monoclonal) anti-A antibodies. E. coli Y1089 and Y1090 have endogenous enzymes that use the A-sugar (in the absence of A-transferase) to produce a variant A antigen. Cells expressing this variant antigen adsorb anti-A antibodies but do not participate in mixed agglutination with human group A red cells. It is estimated that E. coli Y1089 and Y1090 possess approximately 5000 H epitopes per cell that can be converted to A epitopes.

ABO Blood-Group System↗