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Biomedical subjects

N Wu

Publications and source records attributed to N Wu.

At least 109 records · Page 6Linked to original sources
PubMed1993

Evidence that both receptor- and heparan sulfate proteoglycan-bound basic fibroblast growth factor are internalized by cultured immature Leydig cells.

The present studies examined how 125I-labeled basic fibroblast growth factor (bFGF) bound to high affinity receptors and with lower affinity to heparan sulfate proteoglycans (HSPG) of cultured immature rat Leydig cells was processed. Following incubation for 2 h at 4 degrees C with 125I-bFGF, cells were washed to remove unbound radioactivity. Fresh medium was added, and cells were incubated at 4 degrees and/or 37 degrees C. At time zero and at specific intervals over the next 6 h, the incubation medium was saved and cells washed to quantitate 125I-bFGF released into the medium, associated with HSPG of the cell surface or extracellular matrix (radioactivity released by washing cells with 2 M NaCl, pH 7.4), associated with cell surface receptors (radioactivity released by washing cells with 2 M NaCl, pH 4.0) or internalized (radioactivity resistant to high salt and acid washes, and solubilized with 0.5 M NaOH). Radioactivity released into the initial medium and the pooled washes was further divided into a trichloroacetic acid (TCA)-precipitated form (radioactivity precipitated by 10% TCA) and a TCA-soluble form (radioactivity remaining in the TCA supernatant). 125I-bFGF associated with both HSPG and surface receptors declined progressively during the first 4 h of incubation before stabilizing when cells were transferred to 37 degrees C. These declines were associated with a corresponding increase in intracellular 125I-bFGF. These changes were blocked by maintaining cells at 4 degrees C. The majority of internalized 125I-bFGF appeared to originate from the HSPG-bound fraction as there was a greater decline in HSPG-associated radioactivity and most of the increase in internalized radioactivity could be blocked by the inclusion of 10 micrograms/ml heparin (which mainly blocks 125I-bFGF binding to HSPG but not to high affinity receptors) during the initial incubation with 125I-bFGF for 2 h at 4 degrees C. Furthermore, HSPG-mediated internalization appeared to have two components: the major fraction was blocked by the inclusion of 10 micrograms/ml heparin, while a heparin-resistant fraction, appeared to be closely linked both quantitatively and temporarily to receptor-mediated internalization. A minor fraction of internalized 125I-bFGF was metabolized in lysosomes, as the inclusion of 50 microM chloroquine during the 6 h incubation at 37 degrees C inhibited most of the increase in TCA-soluble radioactivity appearing in the incubation medium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Effects of acidic fibroblast growth factor on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase and 5 alpha-reductase activities and [125I]human chorionic gonadotrophin binding in cultured immature Leydig cells.

The present studies examined the effects of acidic fibroblast growth factor (aFGF) on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase (3 beta-HSD) and 5 alpha-reductase activities and [125I]human chorionic gonadotrophin ([125I]hCG) binding in cultured immature rat Leydig cells. Increasing concentrations of aFGF (0.1-20 ng/ml) progressively decreased basal 3 beta-HSD activity from 0.474 +/- 0.0335 to 0.093 +/- 0.0004 nmol progesterone/30 min/10(5) cells. This inhibition by aFGF (10 ng/ml) was partially reversed by 1 micrograms/ml insulin or 100 ng/ml insulin-like growth factor-I. Increasing aFGF concentrations (0.1-10 ng/ml) also inhibited hCG-stimulated 5 alpha-reductase activity in a dose-dependent manner, but had only a modest effect on basal enzyme activity. Increasing aFGF (0.1-200 ng/ml) also progressively inhibited [125I]hCG binding in cultured immature Leydig cells. These studies demonstrate a similarity in the inhibitive effects of aFGF with bFGF effects on 3 beta-HSD and 5 alpha-reductase activities and [125I]hCG binding to LH receptors, although, generally, higher aFGF concentrations were required to elicit maximal inhibitive effects. However, a FGF differed from the actions of bFGF on 3 beta-HSD activity and LH receptor levels in that a secondary increase with higher growth factor concentrations was not observed.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Evidence that biphasic effects of basic fibroblast growth factor on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity in cultured immature Leydig cells are mediated by binding to heparan sulfate proteoglycans.

The present studies examined the effects of heparin, heparinase, insulin or insulin-like growth factor-I on basic fibroblast growth factor actions on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity of cultured immature rat Leydig cells. Treatment with basic fibroblast growth factor alone (0.025-20 ng/ml) for 2 days had a biphasic effect on enzyme activity, with lower concentrations (0.025-1 ng/ml) progressively inhibiting activity to approximately 20% of control, while higher concentrations (2.5-20 ng/ml) partially reversed the inhibitive effects. The inclusion of 10 micrograms/ml heparin, a concentration reported to inhibit growth factor binding to heparan sulfate proteoglycans, blocked the increase in enzyme activity elicited by higher growth factor concentrations, but had no effect on the progressive decline in activity due to lower concentrations. Concomitant treatment with heparinase I and III, which specifically hydrolyze heparan sulfate proteoglycans, had a similar effect. In addition, both insulin and insulin-like growth factor-I partially reversed the inhibition of enzyme activity due to treatment with 1 ng/ml basic fibroblast growth factor. These studies suggest that some basic fibroblast growth factor actions on cultured immature Leydig cells are mediated by binding to heparan sulfate proteoglycans, and that both insulin and insulin-like growth factor-I can reverse the inhibitive effects on 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Field evaluation of bednets impregnated with deltamethrin for malaria control.

Trials were undertaken in a hypoendemic area of malaria in an area bordering Vietnam, in Napo County of Guangxi Zhuang Autonomous Region, China. The aim was to compare the relative cost effectiveness of DDT residual spraying and of bednets impregnated with deltamethrin in the malaria control program. The trials were divided into three subgroups: (1) two farming areas and one coal mining area with a total population > 20,000, where the trial consisted of mass bednets impregnated with deltamethrin 15 mg/m2 net surface once a year, (2) one farming area with a population of approximately 3,600 where DDT residual spraying at 2g/m2 was carried out twice a year in May and August; (3) one farming area and one coal mining village with a population of > 4,000 were used as a control. The malaria vector population consisted mainly of Anopheles minimus and An. anthropophagus with a small contribution from An. sinensis. After bednets were impregnated with deltamethrin the mosquitos resting on the surface of the bednets decreased significantly, although there was less effect on the total vector population. The results showed that malaria incidence decreased significantly both in areas where impregnated bednets were used and in areas where residual spraying was undertaken. The positive IFAT rates of residents who slept under impregnated bednets decreased significantly in farming areas, especially in that area where bednet impregnation as a vector control measure had been undertaken for two years, but there was no change in the IFAT rate in DDT sprayed or control areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Bedding and Linens↗
PubMed1993

[The diagnosis and treatment of the secondary glaucoma caused by epithelial ingrowth into the anterior chamber].

This study reports the clinical manifestations of 3 cases (3 eyes) of the secondary glaucoma caused by epithelial ingrowth into the anterior chamber. Based on some clinically suspected signs, we confirmed the diagnosis of epithelial ingrowth by means of the diagnostic argon laser photocoagulation to make the characteristic white burns in the site of the affected iris. Three eyes with epithelial ingrowth underwent extensive laser photocoagulation on the affected iris by delineating the extent of the epithelial membrane before the therapy. Then excisions of the involved iris and pupillary membrane, anterior segment vitrectomy and trabeculectomy were done on two aphakic eyes. The remaining phakic eye only received the thermal sclerostomy combined with sector iridectomy. The epithelial ingrowth was verified postoperatively by the histopathological examination of the specimens from the excised iris. Optimal reductions in intraocular pressures were observed in two eyes with the epithelial ingrowth of the iris (less than 70%), and in another eye with the extensive involvement of the iris (more than 70%). Medical therapy was required to normalize IOP in addition to the surgical procedure. The follow-up period ranged from 8 to 15 months.

Adolescent↗
PubMed1992

Separation of serum bilirubin species by micellar electrokinetic chromatography with direct sample injection.

Four major bilirubin species in serum were separated by micellar electrokinetic chromatography with 25 mM sodium dodecyl sulfate (SDS) and 20 mM sodium tetraborate-boric acid buffer at pH 8.5. Due to the solubilization of the serum proteins by the SDS micelles, serum samples were injected directly into a 50 cm x 75 microns I.D. fused-silica capillary and complete separation of the four bilirubin species was accomplished within ca. 10 min without extensive sample pretreatment. Detection was performed by absorbance at 450 nm and average limit of detection was in the 6.0 microM concentration range. The usefulness of this method was demonstrated for the separation and detection of a number of bilirubin species present in pathological human serum samples.

Animals↗
PubMed1992

Evidence for basic fibroblast growth factor receptors in cultured immature Leydig cells.

Previous studies have shown that basic fibroblast growth factor (bFGF) can modulate basal and luteinizing hormone/human chorionic gonadotropin (LH/hCG)-stimulated Leydig cell functions. It has not been ascertained whether these actions are due to direct or indirect effects on Leydig cells. To resolve this question, a multi-step procedure was used to isolate highly-purified Leydig cells from immature rats. 125I-bFGF binding studies were performed on cultured cells. Scatchard analysis of the data indicated a single binding site with an apparent Kd of 82 pM and a binding capacity of approximately 2800 sites per cell. Both bFGF and acidic FGF similarly were effective in displacing 125I-bFGF, suggesting that the receptor binds both bFGF and aFGF. However, neither hCG, follicle-stimulating hormone (FSH), insulin, insulin-like growth factor-1 (IGF-1), prolactin, platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) were effective competitors. When binding studies were conducted on cultured testicular interstitial cellular fractions that are normally discarded during Leydig cell purification, bFGF receptors were identified in these fractions. These results demonstrate that bFGF can have direct effects on Leydig cells through specific receptors; however, because other interstitial cell type(s) also have bFGF receptors, they stress the importance of using highly purified cells when evaluating bFGF actions on Leydig cells.

Animals↗
PubMed1992

Cloning and nucleotide sequence of chloroplast psaA gene from sorghum.

The 6.7 kb EcoRI fragment containing the sorghum chloroplast psaA gene was cloned. The restriction endonuclease map and the nucleotide sequence were determined. The length of the determined nucleotide sequence was 3080 bp, of which the psaA coding sequence was 2253 bp, which encoded a polypeptide of 750 amino acids with a estimated molecular weight of 83000. The homologies of this psaA gene of sorghum with those of maize, rice and spinach were 99.4%, 96.3% and 89.4%, respectively, and the homologies of the deduced polypeptide sequences were 99.3%, 98.0% and 95.7%, respectively. We found that a difference in the profiles of the hydrophobic distribution of P700 apoproteins existed between C4 and C3 plants due to a change occurred at the 493th amino acid (C4 plants: Gly; C3 plants: Arg or Ser).

Amino Acid Sequence↗
PubMed1992

[Expression and secretion of alpha-amylase gene from Bacillus subtilis in E. coli].

The E. coli which carrying the alpha-amylase gene fragment cloned from B. subtilis secreted the gene products into the medium. The reason is the exogenous gene fragment act on the cell wall of E. coli by some way, gives rise to the change of its structure. It leads up to the alpha-amylase and some periplasm proteins passing through the cell wall into the medium. It also causes the change of host colonial morphology. The secrete process are non-specific.

Bacillus subtilis↗
PubMed1992

[Prognosis and factors predicting the long-term prognosis of myocardial infarction].

200 cases of consecutively admitted acute myocardial infarction (AMI), who had survived for at least 2 weeks, were studied prospectively. 193 cases were followed-up for 0.5-27 (average 15) months; 41 of them (21.2%) had cardiac events, including 3 sudden cardiac death (1.6%) and 35 obvious cardiac failure (18.1%). 11 patients died of heart failure and 4 of reinfarction. Before discharge, noninvasive tests were done: LVEF < or = 40%, age > or = 60, maximum value of creatinine-phosphokinase > or = 1000 IU/dl and positive ventricular late potential were the 4 factors of high risk. Patients with 3 or 4 positive risk factors had poorer prognosis, if they were compared with those with one or none.

Age Factors↗
PubMed1992

Clinical manifestations and prevalence of different types of supraventricular tachycardia among Chinese.

Sixty-nine cases of paroxysmal supraventricular tachycardia (PSVT) were submitted to electrophysiological studies. The prevalence of different types of PSVT is as follows: 49% of the cases had atrioventricular reentry tachycardia (AV-RT), 14.5% atrioventricular nodal reentry tachycardia (AVN-RT), 28% AV + AVN - RT, and 8.5% other types. Altogether 77% in this group had atrioventricular accessory pathway, of which half are concealed pathway. Electrocardiographic characteristics during tachycardia give hints to diagnosis: (1) AV - RT has the fastest heart rate, with 62% 200 BPM or more, and 82% more than 188 BPM; (2) retrograde P waves can be detected in 64% of cases with AV bypass; (3) 50% of AV - RT shows QRS of bundle branch block pattern. Since accessory pathways are present in the majority of PSVT patients in China, the importance of treatment is stressed.

China↗
PubMed1991

Expression of human glycophorin A in wild type and glycosylation-deficient Chinese hamster ovary cells. Role of N- and O-linked glycosylation in cell surface expression.

Glycophorin A, the most abundant sialoglycoprotein on human red blood cells, carries several medically important blood group antigens. To study the role of glycosylation in surface expression and antigenicity of this highly glycosylated protein (1 N-linked and 15 O-linked oligosaccharides), glycophorin A cDNA (M-allele) was expressed in Chinese hamster ovary (CHO) cells. Both wild type CHO cells and mutant CHO cells with well defined glycosylation defects were used. Glycophorin A was well expressed on the surface of transfected wild type CHO cells. On immunoblots, the CHO cells expressed monomer (approximately 38 kDa) and dimer forms of glycophorin A which co-migrated with human red blood cell glycophorin A. The transfected cells specifically expressed the M blood group antigen when tested with mouse monoclonal antibodies. Tunicamycin treatment of these CHO cells did not block surface expression of glycophorin A, indicating that, in the presence of normal O-linked glycosylation, the N-linked oligosaccharide is not required for surface expression. To study O-linked glycosylation, glycophorin A cDNA was transfected into the Lec 2, Lec 8, and ldlD glycosylation-deficient CHO cell lines. Glycophorin A with truncated O-linked oligosaccharides was well expressed on the surface of ldlD cells (cultured in the presence of N-acetylgalactosamine alone), Lec 2 cells, and Lec 8 cells with monomers of approximately 25 kDa, approximately 33 kDa, and approximately 25 kDa, respectively. In contrast, non-O-glycosylated glycophorin A (approximately 19-kDa monomers) was poorly expressed on the surface of ldlD cells cultured in the absence of both galactose and N-acetylgalactosamine. Thus, under these conditions, in the absence of O-linked glycosylation, the N-linked oligosaccharide itself is not able to support appropriate surface expression of glycophorin A in transfected CHO cells.

Animals↗
PubMed1991

[Analysis of leptospiral deoxyribonucleic acids by restriction endonucleases].

For the application of restriction endonuclease analysis in typing and identifying leptospira, we selected some serovars and isolates, and analysed preliminarily their DNA with four restriction enzymes, EcoR I, Bgl II, Hha I, and Hind III. The DNA samples were isolated from the reference strains and isolates as follows: Serovar lai 56601, 017 (the virulent strain for PDH model of guinea pig), Serovar autumnalis 56606, Serovar manhao II 67020, and isolates 87112 and 87369. Each 2 micrograms of DNA was digested with 20mu of restriction enzyme at 37 degrees C for 2h and electrophoresed in 0.8% agarose gel. The gels were stained in ethidium bromide and photographed with UV light. In our experiments, apparently different restriction patterns of serovar lai 017 were observed with four restriction enzymes. Serovar lai, serovar autumnalis and serovar manhao II showed different patterns with EcoR I, especially in high molecular regions. We also observed in serovar lai 017 a distinct 10.5kb band which was obscure in 56601, the reference strain of serovar lai, after EcoR I digestion. The three serovars showed some delicate differences in Hind III restriction pattern. The two isolates from Apodemus agrarius in Sichuan (1987) 87112 and 87369 had patterns identical to those of serovar lai 56601, 017 with EcoR I, and 87112 also had a pattern identical to 56601, 017 with Hind III. Our results indicate that selected three serovars can be identified by analysis of their DNA with EcoR I and Hind III. It is suggested that restriction endonuclease analysis be a good method in typing and identify leptospira and in studying the differences of special DNA molecules.

DNA Restriction Enzymes↗
PubMed1991

[Determination of pancreatic blood flow at the early stage of acute haemorrhagic necrotizing pancreatitis induced by sodium taurocholate in rats].

Acute haemorrhagic necrotizing pancreatitis was induced by injecting 5% sodium taurocholate (Na-Tc) directly into the common biliopancreatic duct in rats. In control group 0.9% NaCl was used. The activity of serum lipase and amylase distinctly increased at 3 h and went up to the maximum at 12 h after injection of Na-Tc. The pancreatic blood flow and tissue perfusion per gram increased apparently at 1 h and decreased at 12 h after injection of Na-Tc by using the fractional indicator distribution technique with 86RbCl. The results demonstrated that the early stage of acute haemorrhagic necrotizing pancreatitis induced by Na-Tc in rats was still a primary inflammatory response.

Acute Disease↗