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M Wang

Publications and source records attributed to M Wang.

At least 199 records · Page 11Linked to original sources
PubMed2001

Role of zinc-finger motif in redox regulation of human replication protein A.

Replication protein A (RPA) is a heterotrimeric zinc-finger protein complex involved in DNA replication, repair, and genetic recombination. Unlike other zinc-finger proteins, RPA's zinc-finger motif is not essential for its single-stranded DNA (ssDNA) binding activity, but is involved in redox regulation of its single-stranded DNA (ssDNA) binding activity. To get an insight into the regulation of RPA-ssDNA interaction, wild-type RPA (wt-RPA) and zinc-finger mutant were examined for ssDNA binding activity using surface plasmon resonance technique. Interaction of wt-RPA with ssDNA under nonreducing conditions was very weak (KD x 2.33 x 10(-8) M) compared with that under reducing conditions (KD = 7.35 x 10(-11) M), whereas ssDNA binding affinity of the zinc-finger mutant was not affected by redox. The divalent ion chelator, o-phenanthroline, significantly reduced wt-RPA-ssDNA interaction, but had no effect on the zinc-finger mutant. The inhibitory effect of o-phenanthroline on RPA-ssDNA interaction was reversed by Zn(II), but not by other divalent cations, suggesting that Zn(II) is the unique metal coordinating the zinc-finger cysteines in redox regulation of RPA-ssDNA interaction. In DNA repair, redox affected RPA's interaction with damaged DNA, but not its role in stabilizing the xeroderma pigmentosum group A (XPA)-damaged DNA complex, suggesting that the zinc-finger motif may mediate the transition of RPA-XPA interaction to a stable RPA-XPA-damaged DNA complex in a redox-dependent manner.

Animals↗
PubMed2001

Absence of memory for intra-operative information during surgery with total intravenous anaesthesia.

While using the isolated forearm technique, we wished to determine whether patients who did not respond to commands during general anaesthesia with a total intravenous technique (propofol and alfentanil with atracurium) had any evidence of post-operative explicit or implicit memory. Forty women undergoing major gynaecological surgery were randomized, in a double-blind design, to hear two different tapes during surgery. Psychological tests of explicit and implicit memory were conducted within 2 h of surgery. There was no evidence of implicit or explicit memory, nor any recall, in the seven women who responded to commands during surgery. We conclude that during total intravenous anaesthesia with propofol and alfentanil, there is no evidence that learning takes place when anaesthesia is adequate. Furthermore, with this anaesthetic technique, it would seem that--provided any period of patient responsiveness is short and that unconsciousness is induced rapidly again--there is no evidence of implicit or explicit memory.

Adult↗
PubMed2001

The calciuric response to dietary salt of Dahl salt-sensitive and salt-resistant male rats.

BACKGROUND: There are conflicting reports regarding the effect of salt sensitivity on the calciuric response to salt, perhaps because of gender differences and different modes of salt administration. We tested the hypothesis that the calciuric response to dietary salt would not differ for male Dahl salt-sensitive (S) and salt-resistant (R) rats. METHOD: S and R rats were fed high- (80 g/kg) or low- (3 g/kg) salt diets for 3 weeks and urine (24 hour) was collected weekly. RESULTS: Urinary calcium excretion was up to 20-fold greater for S and R rats fed a high-salt diet (P < 0.001) than for S and R rats fed a low-salt diet and did not differ significantly between S and R rats. S rats, however, excreted calcium in significantly higher urine volumes (P< 0.001) during high salt intake and developed hypertension. Plasma parathyroid hormone concentrations of S and R rats did not differ during low salt intake and increased significantly to the same concentration after 3 weeks of high salt intake. CONCLUSIONS: We have previously reported that plasma 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations of male S rats, but not male R rats, were drastically reduced by 3 weeks of high salt intake. These data suggest that salt-induced hypertension and salt-induced alterations in the vitamin D endocrine system of male S rats do not affect the calciuric response to dietary salt.

Animals↗
PubMed2001

The calciuric response to dietary salt of Dahl salt-sensitive and salt-resistant female rats.

BACKGROUND: We have shown previously that the calciuric response to salt does not differ in Dahl salt-sensitive (S) and salt-resistant (R) male rats. Clinical studies with women, however, suggest an effect of salt sensitivity on the calciuric response to salt. The objective of this study was to determine whether there is an effect of salt sensitivity on the calciuric response to salt of female S and R rats. METHOD: Dahl S and R female rats were fed high- (8%) or low- (0.3%) salt diets for 3 weeks. The rats were placed in metabolic cages for 24-hour urine collection at baseline and weekly (for sodium and calcium determination). RESULTS: Blood pressure of female S rats was 177+/-3.0 mm Hg at week 3 of high salt intake compared with 96+/-1 mm Hg for female R rats. Female S rats excreted significantly more calcium than female R rats at baseline (P < 0.001), when fed a nonpurified diet, and during high salt intake (P = 0.004). Salt sensitivity significantly increased calcium excretion, water intake, and urine output when rats were fed a high-salt diet. Calcium excretion, water intake, and urine output of female S rats were time-dependent during high salt intake. Plasma 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations were markedly lower in female S rats fed a high-salt diet, but not in female R rats. Plasma parathyroid hormone and 1,25-dihydroxyvitamin D concentrations did not significantly differ between female S and R rats, but plasma concentrations of these two hormones at week 3 were significantly higher in S rats fed a high-salt diet compared with S rats fed a low-salt diet. CONCLUSIONS: Our data indicate that the calciuric response to salt is greater in female S compared with female R rats, thus supporting findings on the effect of salt sensitivity reported in several clinical studies with women. The greater calciuric response to salt of female S rats compared with female R rats, which was not seen in a previous study when male S rats were compared to male R rats, suggest a gender difference in the calciuric response to salt.

Animals↗
PubMed2001

Pullout strengths of self-reinforced poly-L-lactide (SR-PLLA) rods versus Kirschner wires in bovine femur.

OBJECTIVE: To determine the relative amount of fixation of self-reinforced poly-L-lactide (SR-PLLA) rods and Kirschner wires in bovine cancellous bone by comparing their pullout strength DESIGN: An in vitro laboratory study was performed using bovine femurs. Ten two-millimeter-diameter pins of each type were inserted into cancellous bone and then pulled out, using a material testing machine. The maximum force (pullout strength) was selected over other measurements to compare the amount of fixation of the two types of pins. All of the pins were retrieved for microscopic analysis. A paired t test was performed to analyze the differences between the pullout strength of the two types of pins. SETTING: Orthopaedic Bioengineering Laboratory, University of Louisville School of Medicine, Louisville, Kentucky, U.S.A. SPECIMENS: Two young fresh bovine distal femurs, ten two-millimeter-diameter Kirschner wires, ten two-millimeter-diameter bioabsorbable SR-PLLA rods MAIN OUTCOME MEASUREMENTS: Pullout strength in Newtons, and microscopic pin surface aspect after insertion. RESULTS: Significant differences were noted between the maximum force required to remove the two types of pins (p < 0.01) The K-wire mean pullout force was 37.7 N (SD 13.6), and the SR-PLLA rod mean pullout force was 53.6 N (SD 19.3). Microscopic analysis indicated surface modification only on the SR PLLA rods. DISCUSSION: SR-PLLA composites have shown comparable clinical results to their metallic counterparts. In this study, the pullout strength of SR-PLLA rods was compared with that of conventional K-wires. A significant difference (p < 0.01) favoring bioabsorbable pullout strength was noted. The bioabsorbable pin surface modification during insertion is an interesting finding that warrants further investigation as a potential source of improved fixation. CONCLUSION: SR-PLLA rods retain their hold in bovine cancellous bone better than K-wires. This finding offers to the orthopaedic surgeon more information about new pin fixation methods.

Animals↗
PubMed2001

Pulmonary function in long-term asbestos workers in China.

The relationship of pulmonary function to exposure to asbestos and radiographic abnormalities has been controversial, especially when smoking is present as a confounder. The aim of the study was to provide further understanding on the radiographic-physiologic associations in nonsmoking and smoking asbestos workers. Radiographic asbestosis, pleural lesion, and pulmonary function were studied in 269 Chinese asbestos workers, with average exposure years of 23 for male workers and 18 for female workers. Their functional data were compared with those of 274 controls without exposure to dust. Although most of the male workers were smokers, none of the female workers smoked. In comparison with controls, asbestos workers had significantly lower lung volume and diffusing capacity, irrespective of gender. Female workers and smoking male workers had lower measurements of forced expiratory volume in 1 second and instantaneous forced expiratory flow at 50% and 25% of forced vital capacity. After adjustment for relevant covariates, asbestos exposure, asbestosis, and pleural abnormalities were associated with decreased parameters of pulmonary function, including lung volume, diffusing capacity, and airway flow. These data indicate that asbestos-related functional defects manifested by lung restriction and mild airway obstruction correlate with exposure to asbestos and with parenchymal and pleural abnormalities, independent of smoking.

Adult↗
PubMed2001

Broadly neutralizing antibodies targeted to the membrane-proximal external region of human immunodeficiency virus type 1 glycoprotein gp41.

The identification and epitope mapping of broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies (Abs) is important for vaccine design, but, despite much effort, very few such Abs have been forthcoming. Only one broadly neutralizing anti-gp41 monoclonal Ab (MAb), 2F5, has been described. Here we report on two MAbs that recognize a region immediately C-terminal of the 2F5 epitope. Both MAbs were generated from HIV-1-seropositive donors, one (Z13) from an antibody phage display library, and one (4E10) as a hybridoma. Both MAbs recognize a predominantly linear and relatively conserved epitope, compete with each other for binding to synthetic peptide derived from gp41, and bind to HIV-1(MN) virions. By flow cytometry, these MAbs appear to bind relatively weakly to infected cells and this binding is not perturbed by pretreatment of the infected cells with soluble CD4. Despite the apparent linear nature of the epitopes of Z13 and 4E10, denaturation of recombinant envelope protein reduces the binding of these MAbs, suggesting some conformational requirements for full epitope expression. Most significantly, Z13 and 4E10 are able to neutralize selected primary isolates from diverse subtypes of HIV-1 (e.g., subtypes B, C, and E). The results suggest that a rather extensive region of gp41 close to the transmembrane domain is accessible to neutralizing Abs and could form a useful target for vaccine design.

Amino Acid Motifs↗
PubMed2001

Neutralization synergy of human immunodeficiency virus type 1 primary isolates by cocktails of broadly neutralizing antibodies.

Several reports have described the existence of synergy between neutralizing monoclonal antibodies (MAbs) against human immunodeficiency virus type 1 (HIV-1). Synergy between human MAbs b12, 2G12, 2F5, and 4E10 in neutralization of primary isolates is of particular interest. Neutralization synergy of these MAbs, however, has not been studied extensively, and the mechanism of synergy remains unclear. We investigated neutralization synergy among this human antibody set by using the classical approach of titrating antibodies mixed at a fixed ratio as well as by an alternative, variable ratio approach in which the neutralization curve of one MAb is assessed in the presence and absence of a fixed, weakly neutralizing concentration of a second antibody. The advantage of this second approach is that it does not require mathematical analysis to establish synergy. No neutralization enhancement of any of the MAb combinations tested was detected for the T-cell-line-adapted molecular HIV-1 clone HxB2 using both assay formats. Studies of primary isolates (89.6, SF162, and JR-CSF) showed neutralization synergy which was relatively weak, with a maximum of two- to fourfold enhancement between antibody pairs, thereby increasing neutralization titers about 10-fold in triple and quadruple antibody combinations. Analysis of b12 and 2G12 binding to oligomeric envelope glycoprotein by using flow cytometry failed to demonstrate cooperativity in binding between these two antibodies. The mechanism by which these antibodies synergize is, therefore, not yet understood. The results lend some support to the notion that an HIV-1 vaccine that elicits moderate neutralizing antibodies to multiple epitopes may be more effective than hereto supposed, although considerable caution in extrapolating to a vaccine situation is required.

AIDS Vaccines↗
PubMed2001

Immunomodulating activity of CVT-E002, a proprietary extract from North American ginseng (Panax quinquefolium).

The activity of CVT-E002, an aqueous extract containing mainly oligosaccharides and polysaccharides from North American ginseng (Panax quinquefolium), as an immunobooster on murine spleen cells and peritoneal macrophages, was studied in-vitro. CVT-E002 stimulated the proliferation of normal mouse spleen cells, of which the major responding subpopulation was identified as B lymphocytes. CVT-E002 also activated peritoneal exudate macrophages leading to enhanced interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) production. In addition, CVT-E002 stimulated in-vivo immunoglobulin G (IgG) production in treated mice. These results identify some of the immunomodulating activities of CVT-E002 and suggest its use clinically for the modulation of immune responses.

Adjuvants, Immunologic↗
PubMed2001

Objective sleepiness measures in pediatric obstructive sleep apnea.

OBJECTIVES: Excessive daytime sleepiness (EDS) occurs frequently in adult patients with obstructive sleep apnea (OSA). However, the incidence of EDS in children with OSA is unknown. METHODS: To determine overall daytime sleepiness in pediatric OSA, 54 children with OSA, 14 children with primary snoring (PS), and 24 controls (C) underwent an overnight diagnostic polysomnogram followed the next day by a multiple sleep latency test. RESULTS: The mean apnea index was 15.1 +/- 9.5 standard deviation in OSA, 1.1 +/- 0.5 in PS, and 0.1 +/- 0.3 in C. Mean sleep latencies were 23.7 +/- 3.0 minutes in C, 23.7 +/- 3.1 minute in PS, and 20.0 +/- 7.1 minute in OSA patients. However, only 7 children with OSA had mean sleep latencies <10 minutes. In addition, shorter sleep latencies were more likely to occur in more obese OSA patients and those with more severe apnea index, and oxyhemoglobin desaturation. CONCLUSIONS: Shortened sleep latencies occur in children with OSA, but EDS is infrequent and tends to develop among more severe and/or obese patients.

Case-Control Studies↗
PubMed2001

Up-regulation of transcription of smooth muscle myosin alkali light chain by ethanol in human breast cancer cells.

Both epidemiological and experimental studies indicate that ethanol is a tumor promoter and that chronic ethanol exposure enhances metastasis of breast cancer cells, and with an in vitro model (T47D human breast cancer cells), we have previously demonstrated that ethanol exposure stimulated the migration of breast cancer cells. In the present study, differential display reverse transcription polymerase chain reaction was used to identify ethanol-responsive genes in T47D cells. Three differentially displayed, ethanol-responsive gene fragments were identified, and their expression was confirmed by Northern blot hybridization. Sequence analysis revealed that one cDNA fragment represented the myosin alkali light chain (MLC 1sm) of human smooth muscle. The expression of MLC 1sm was found to be significantly higher in breast cancer cells than in normal mammary epithelial cells. With T47D cells, ethanol induced an additional duration- and concentration-dependent up-regulation of MLC 1sm. At 400 mg/dl, an ethanol-mediated increase was evident at 6 h (55% increase), peaked at 24 h (2.7-fold increase) following exposure, and diminished thereafter. At pharmacologically relevant concentrations (e.g., 100 mg/dl), ethanol produced a significant increase of MLC 1sm expression, and progressively higher ethanol concentrations resulted in more up-regulation. The half-life of MLC 1sm mRNA was not altered, however, the transcription rate of MLC 1sm was significantly increased by ethanol. MLC is a structural component of the cytoskeleton of eukaryotic cells, and it plays critical roles in the regulation of cell shaping, movement, and growth. Thus, ethanol-mediated up-regulation of MLC may be an underlying molecular mechanism for its tumor promoting effect.

Blotting, Northern↗
PubMed2001

[Study on polymorphism of D gene exons among RhD-negative Chinese Han population].

OBJECTIVE: To explore the genomic structure of 8 exons in D gene of RhD(-) Chinese Han population. METHODS: Polymerase chain reaction-sequence specific primers(PCR-SSP) were used to study genomic DNA from 50 samples of RhD(-) Chinese Han donors. Exons 2, 3, 4, 5, 6, 7, 9, 10 of RHD gene and exons 1, 2, 4, 5 of RHCE gene were specifically amplified, also intron 4 of them was amplified. RESULTS: Phenotypes of the 50 RhD(-) donors were: 22 ccdee, 22 Ccdee, 3 CcdEe, 3 CcdEe. The 8 exons of RHD gene were completely absent in 25 donors with ccdee or ccdEe phenotype, while polymorphisms of D gene exons were found in 25 donors with Ccdee or CcdEe phenotype: the presence of all 8 exons of D gene in 9 donors, the absence of the 8 exons in 7 donors, the presence of exon 2 in 5 donors, the presence of exon 6 in 3 donors and the presence of exons 2, 6, 10 in 1 donor were demonstrated. CONCLUSION: Polymorphisms of RHD gene exons were present among RhD(-) Chinese Han blood donors. The 8 exons of RHD gene were completely absent in donors with Rhesus cc phenotype, while 5 polymorphisms of RHD gene exons were found in donors with Rhesus Cc phenotype. The discrepancy of the RHD gene in RhD(-) individuals between Chinese Hans and Caucasians indicates that care should be exercised by clinicians in the use of the RhD genotyping results.

China↗
PubMed2001

[Cloning and primary expression analyses of down-regulated cDNA fragment in human gastric cancer].

OBJECTIVE: To identify human gastric cancer related genes. METHODS: Specimens of paired tumor, paratumor and normal gastric mucosa tissues were collected from five patients (male 3, female 2, with average age 48.8 +/- 18.1 years) who suffered from stomach antrum adenocarcinoma. Total RNA samples were extracted from these specimens, then studied by fluorescent differential display reverse transcription polymerase chain reaction (DDRT- PCR) analysis. The differentially expressed bands of interest were recovered, purified and cloned, then they were analyzed by sequencing, Northern blot and RT-PCR. Through BLAST, the sequencing results were compared with GenBank database for homology analysis. RESULTS: One of the interesting cDNA bands expressed much lower in all five tested tumor samples than in their normal and paratumor counterparts. This band was named W4. Northern blot analysis showed a consistent result with that of DDRT-PCR. W4 was cloned into pGEM-T easy vector. Sequence analysis showed that W4 consists of 712bp, this sequence was named W44. BLAST analysis revealed that W44 has extremely low sequence identity with any genes from GenBank and any sequences from EST database. This sequence data was submitted to GenBank with accession No. AF150631. RT-PCR analysis showed that W4 was expressed much lower in 11/15 gastric cancer tissue than in paratumor and normal samples. CONCLUSION: A novel cDNA sequence related to human stomach adenocarcinoma was identified.

Adult↗
PubMed2001

[Role of protein kinase in the proliferation of human embryonic pulmonary fibrolasts stimulated by the supernatants of crocidolite-exposed alveolar macrophages].

In order to study the role of protein kinase in the proliferation of lung fibroblasts induced by crocidolite. An in vitro model was established by rabbit alveolar macrophage (AM) and human embryonic pulmonary fibroblasts (HEPF). Using MTT color response method to measure HEPF proliferation, the influence of the inhibitor or activator of protein kinase (PKA, PKC and TPK) on the proliferation of crocidolite-induced HEPF were investigated. TiO2 was taken as negative control and SiO2 positive control. The results showed that the inhibitors of PKA, PKC and TPK could all inhibit the proliferation of HEPF induced by crocidolite, their activators could also promote the proliferation of HEPF. There all existed significant dose-effect relationships (P < 0.01), and the intensity in crocidolite group was inhibited or activated more than that in the controls. Through acting intensity analysis, the intensity was found as follows: TPK > PKC > PKA. It was suggested that TPK, PKC and PKA signal pathways were all involved in the process of the proliferation of crocidolite-induced HEPF, but TPK maybe played a key role in this process. This study provide leads for further research on identifying the bioactive factors of proliferation of crocidolite-induce HEPF.

Animals↗
PubMed2001

[Non-invasive prenatal diagnosis of Duchenne muscular dystrophy].

OBJECTIVE: This paper was designed to investigate the feasibility of non-invasive prenatal diagnosis of Duchenne muscular dystrophy(DMD). METHODS: The nucleated red blood cells(NRBC) were separated with percoll using a discontinuous density gradient method. The cells were smeared on microscope slides using a cyto-centrifuge and then stained by Wright- Giemsa. NRBCs were detected and individually retrieved into glass capillary pipettes using a micromanipulator under microscopic observation. The whole genome of a single cell was amplified by improved primer extension preamplification(PEP). The procedures for making prenatal diagnosis of DMD and determining the origin of NRBCs proceeded at the same time using sex determination and linkage analysis of several STR loci of dystrophin. Genotypes were analyzed by amplifying the 9 STR fragments using fluorescence-PCR technique and NRBCs origin was further determined. RESULTS: A case of DMD in male fetus was diagnosed. CONCLUSION: With the use of the method reported, the non-invasive prenatal diagnosis of DMD is possible.

Female↗
PubMed2001

[Expression of rasp21, C-myc, C-erbB-2, and AFP in 2-FAA induced experimental hepatocarcinogenesis].

OBJECTIVE: To investigate the distribution of oncogenes and their relationships in 2-FAA induced experimental hepatocarcinogenesis. METHODS: Rasp21, C-myc, C-erbB-2, and AFP were detected and analyzed by the SP method of immunohistochemistry. RESULTS: Some cells expressed rasp21, C-myc, and AFP in peripheral liver lobules and alternated hepatocyte foci in the early stage of the experiment. And with the formation and progression of hyperplastic hepatocytic nodules, expressed cells increased and often accompanied each other. Expression of C-erbB-2 appeared in the middle stage of the hepatocarcinogenesis. CONCLUSIONS: Expression of rasp21, C-myc, and AFP in the experimental hepatocarcinogenesis is an early molecule change, which may relate to the initiation of hepatocarcinogenesis and be considered to be one of the molecular bases for the morphogenesis of hepatocarcinogenesis. During the development of lesion, C-erbB-2 may have promoting effects. It is also clear that malignant transformation of hepatocyte needs the cooperation of multiple oncogenes.

2-Acetylaminofluorene↗
PubMed2001

[Mass concentration and major inorganic compositions of coastal aerosol in Qingdao].

Five times measurements of atmosphere aerosol were conducted from September, 1997 to November, 1998 at a coastal site of Qingdao. The mass concentrations of aerosol and their main soluble compositions were measured. The mass concentration and seasonal variation of the aerosol and its composition were discussed by different size. The PM2.5 (d < 2.5 microns) mass concentration accounts for half of the TSP, while the PM10 (d < 10 microns) mass concentration is about 75% of the TSP. More than 40% of the TSP mass concentration are from that of the soluble ions, among which SO4(2-), NO3- and NH4+ are the primary ones. SO4(2-), NH4+, NO3- are mainly in fine particles which suggest that they mainly existed in secondary aerosols. The mass concentrations of TSP in winter are much higher than those in other seasons.

Aerosols↗