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Biomedical subjects

W H Zhang

Publications and source records attributed to W H Zhang.

At least 19 recordsLinked to original sources
PubMed2003

Short-term outcome of isolated and associated congenital heart defects in relation to antenatal ultrasound screening.

OBJECTIVE: To investigate the outcome of fetuses affected by congenital heart defects (CHD), either detected or undetected at ultrasound screening, according to their complexity and severity. DESIGN: The study group comprised 3633 malformed fetuses entered into the Eurofetus database of which 798 had CHD. We compared the short-term outcome in cases where a CHD was detected by ultrasound screening with that in cases where a CHD was not detected. Isolated and associated CHD (ICHD and ACHD) and the degree of severity of defects were considered separately. Outcome data included termination of pregnancy (TOP), intrauterine fetal death, neonatal death (< 6 days after birth), gestational age at diagnosis and at delivery, mode of delivery and birth weight. RESULTS: Of the 798 fetuses with CHD, 595 had ICHD and 203 had ACHD. The diagnosis of an anomaly was made significantly earlier in ACHD cases. TOP was chosen in 28% of cases with a prenatal diagnosis of CHD, 20% for ICHD and 37% for ACHD (P < 0.001). The survival rate of antenatally diagnosed fetuses was lower in those with ACHD than in those with ICHD (P < 0.001) and lower for fetuses with antenatal diagnosis than with postnatal diagnosis (P < 0.001); this was due to significant differences in the complexity and severity of the defect. Premature delivery (< 32 weeks) was more frequent in fetuses in which an antenatal diagnosis of CHD had been made. Severe CHD were diagnosed earlier and were associated with a higher rate of TOP and spontaneous loss. CONCLUSIONS: The severity of CHD has a positive influence on the sensitivity of screening but a negative influence on the outcome. CHD that are not diagnosed antenatally include a high proportion of benign malformations. This explains the apparent paradox of a poorer outcome in fetuses in which a CHD was detected prenatally compared to those fetuses in which the defect was undetected prenatally. However, prenatal diagnosis provides parents with the option of TOP or of preventive care in specialized centers.

Female↗
PubMed2003

Variation of microcystins in a lake for water supply.

A site investigation was conducted to correlate the relationships between microcystins (MC) concentration and algal growth in Dianchi Lake in China. Laboratory experiments were undertaken to test the effects of sediment adsorption, photoirradiation and biodegradation on microcystins removal. Bioaccumulation of microcystins was also determined using silver carp fish. It was observed that MC concentrations varied in accordance with algae growth in Dianchi Lake. The results obtained in the laboratory demonstrated that the removal of MC with fresh sediments was less than 10%, photoirradiation removed more than 75% MC within two hours, and the biodegradation needed much longer time to produce substantial degradation of MC. The results suggest that bioaccumulation of microcystins in fish was not significant in Dianchi Lake.

Animals↗
PubMed2003

Fluctuation of microcystins in water plant.

This study was undertaken to investigate the distribution and variation of microcystins (MC) from a water resource to a water plant in China including long distance transportation, ClO2 preoxidation, coagulation/precipitation, filtration, and disinfection. Advanced treatment methods including ozonation and granular activated carbon (GAC) adsorption were tested to remove microcystins from drinking water. The results indicated that, when containing high level of algae in raw water, preoxidation at 2 mg/L of ClO2 was not enough to stop algae growth in long distance transportation. In the water plant studied, both coagulation and filtration caused significant increase instead of removal of microcystins in drinking water. Chlorine disinfection removed part of microcystins. However, both ozonation and GAC adsorption were able to remove microcystins completely, thereby improving the quality of drinking water in terms of microcystins.

China↗
PubMed2002

Growth inhibitory activity of lemnabourside on human prostate cancer cells.

Induction of apoptosis and androgen ablation are two major approaches for treating human prostate carcinoma. In a study of the bioactive components of the soft coral Nephthea chabroli, we found that lemnabourside is a 5alpha-reductase inhibitor, as shown by its ability to inhibit the conversion of testosterone into the more potent dihydrotestosterone in rat prostate homogenate. The compound also inhibited the incorporation of tritiated thymidine into human prostate androgen-dependent carcinoma LNCaP cells, and thus blocking the cell proliferation (IC50 = 37.5 microM). The expression of prostate marker genes, including 5alpha-reductase, prostate-specific antigen, prostatic acid phosphatase and androgen receptor, and the anti-apoptotic bcl-2 gene were markedly reduced, but the transcription of apoptosis-related caspase 3 gene showed a dose-dependent increase in lemnabourside-treated LNCaP cells. Immunofluorescent microscopy and flow cytometric analysis further demonstrated apoptotic changes in these cells. Taken all results together, a relatively weak 5alpha-reductase inhibitory activity on LNCaP cells (EC50 > 250 microM), and a similar growth inhibitory activity on both androgen dependent- and independent-prostate cells (IC50 approximately 37.5 microM) indicated that caspase-3 apoptosis pathway is one of the possible antiproliferative activities mediated by lemnabourside.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2002

Sensitivity of ultrasound screening for congenital anomalies in unselected pregnancies.

OBJECTIVE: To assess the influence of heart defect frequency and severity on screening sensitivity of the entire spectrum of congenital anomalies (CA) and on detection rate of congenital heart defect (CHD) when performing routine ultrasound screening in unselected pregnant women. STUDY DESIGN: Secondary analysis was performed on data from Eurofetus, a large international collaborative study of ultrasound screening for CA in unselected populations. The present study addressed the relations (i) between the frequency of CHD in the screened population and the global sensitivity of ultrasound in detecting CA; (ii) between frequency of ventricular septum defect (VSD) and detection rate of CA and CHD; and (iii) between seriousness of CHD and CHD sensitivity. RESULTS: A negative correlation (p<0.001) between CHD frequency and CA sensitivity was observed in this study. Likewise, a negative correlation was also found between frequency of VSD and sensitivity for CA or CHD detection (p<0.001). In addition, a positive significant relationship (p<0.001) was observed between sensitivity and severity of CHD. CONCLUSION: A low CHD frequency introduces bias in CA and CHD sensitivity evaluation. Incomplete assessment of fetal and neonatal malformations brings on systematic error, leading to the pre-eminence of severe defects in the studied population sample and artificially improving sensitivity figures. On the other hand, from a clinician's viewpoint, the higher sensitivity for severe defect is welcomed, since their detection is most crucial for appropriate management.

Chi-Square Distribution↗
PubMed2001

CCAAT/enhancer-binding protein alpha alters histone H3 acetylation at large subnuclear domains.

Transcriptional regulation is commonly associated with local levels of histone acetylation, which controls chromatin structure at specific genes or within contiguous chromosomal domains. Less well understood are the higher order determinants of histone acetylation. The transcription factor, CCAAT/enhancer-binding protein alpha (C/EBPalpha), concentrates at one higher order structure, the peri-centromeric chromatin, and regulates differentiation in many cell types, including pituitary cells. We used quantitative fluorescence microscopy to show that immunostained acetylated histone H3 is relatively absent from peri-centromeric domains visible as large structures in mouse pituitary progenitor GHFT1-5 cells. GHFT1-5 cells do not contain C/EBPalpha. We observed that expression of C/EBPalpha in GHFT1-5 cells leads to an increased level of acetylated histone H3, but not acetylated histone H4, at the peri-centromeric domains. Only transcriptionally active forms of C/EBPalpha altered histone acetylation at the peri-centromeric domain. The altered state of histone acetylation at large intranuclear domains may complement, counteract, or supersede the more gene-local activities of other transcription factors to coordinate C/EBPalpha-induced cellular differentiation.

Acetylation↗
PubMed2001

Shanxi Province Cervical Cancer Screening Study: a cross-sectional comparative trial of multiple techniques to detect cervical neoplasia.

OBJECTIVE: The aim of this study was to design a cervical cancer screening algorithm for the developing world that is highly sensitive for cervical intraepithelial neoplasia (CIN) II, III, and cancer and highly specific for CIN II and III, making it possible to ablate the transformation zone without histologic confirmation. METHODS: In rural Shanxi Province, China, we examined 1997 women ages 35-45. Each subject underwent a self-test for intermediate and high-risk HPV (by HC-II assay), fluorescence spectroscopy, a liquid-based Pap (read manually and by computer and used as a direct test for HPV), a visual inspection (VIA) diagnosis, and colposcopy with multiple cervical biopsies. RESULTS: Mean age was 39.1 +/- 3.16 years, mean number of births was 2.6 +/- 0.93. Based on tests administered, 4.3% subjects had > or =CIN II. All subjects with > or =CIN II had either a ThinPrep Pap (> or =ASCUS) or a positive HPV direct test. The sensitivity and specificity for the detection of > or =CIN II were, respectively, 83 and 86% for the HPV self-test, 95 and 85% for the HPV direct test, 94 and 78% for the ThinPrep Pap (> or =ASCUS), 77 and 98% for the ThinPrep Pap (> or =HGSIL), 94 and 9% for fluorescence spectroscopy, 71 and 74% for VIA, and 81 and 77% for colposcopy. CONCLUSION: Based on these data and the existing healthcare infrastructure in China, we believe that further refinement of primary HPV screening using centralized labs is indicated. Self-testing in the local villages may be effective with improvements in the devices and techniques.

Adult↗
PubMed2001

Selenium, iodine and fungal contamination in Yulin District (People's Republic of China) endemic for Kashin-Beck disease.

We studied the status of selenium, iodine and fungal contamination in 353 school children (age 5-14 years) from four rural villages in the District of Yulin. In three villages Kashin-Beck disease (KBD) was endemic, whereas there were no cases of KBD in the fourth village. Clinical, biological and radiological examinations (right hand) were performed and KBD was established by X-ray diagnosis. The prevalence rate of KBD was 30.2%, 44.2% and 45.3% in the three endemic villages. Mean hair selenium and urine iodine concentrations were lower in affected than in unaffected children and fungal contamination in cereal grains stored in families with KBD was more elevated than in families without KBD. Low hair selenium concentration and presence of fungal cereal contamination were significantly associated with an increased risk of KBD, but low urine iodine was not.

Adolescent↗
PubMed2001

Cervical cancer screening by simple visual inspection after acetic acid.

OBJECTIVE: To estimate the sensitivity and specificity of visual inspection using acetic acid as a primary screen for cervical intraepithelial neoplasia (CIN). METHODS: Visual inspection was done on 1997 women aged 35-45 years in a screening trial in rural China. Each women had colposcopy and at least five cervical biopsies (directed biopsy of lesions, one biopsy at 2, 4, 8, or 10 o'clock at the squamocolumnar junction in each normal quadrant, and an endocervical curettage). RESULTS: Forty-three women had biopsy-proven CIN II, 31 had CIN III, and 12 had invasive cancer. In two women only the endocervix was positive (one with CIN II and one with CIN III). Visual inspection yielded normal results in 1445 women (72%), low-grade intraepithelial neoplasia in 525 (26%), high-grade in 21 (1%), and cancer in six (0.3%). With abnormal visual inspection defined as low-grade intraepithelial neoplasia or worse, the sensitivity for detecting biopsy proven CIN II or worse was 71% (61 of 86, 95% confidence interval [CI] 60%, 80%); the specificity was 74% (1420 of 1911, 95% CI 72%, 76%); the sensitivity was 65% for smaller lesions (37 of 57, 95% CI 51%, 77%), and 89% for larger lesions (24 of 27, 95% CI 71%, 98%) (P =.03). CONCLUSION: The sensitivity of visual inspection equaled or exceeded reported rates for conventional cervical cytology. Visual inspection and colposcopy have similar specificity profiles for CIN II and greater. The benefit of an inexpensive point-of-care diagnosis and treatment algorithm will be a powerful incentive to pursue visual inspection for cervical cancer screening in developing countries.

Acetic Acid↗
PubMed2001

Malate-permeable channels and cation channels activated by aluminum in the apical cells of wheat roots.

Aluminum (Al(3+))-dependent efflux of malate from root apices is a mechanism for Al(3+) tolerance in wheat (Triticum aestivum). The malate anions protect the sensitive root tips by chelating the toxic Al(3+) cations in the rhizosphere to form non-toxic complexes. Activation of malate-permeable channels in the plasma membrane could be critical in regulating this malate efflux. We examined this by investigating Al(3+)-activated channels in protoplasts from root apices of near-isogenic wheat differing in Al(3+) tolerance at a single locus. Using whole-cell patch clamp we found that Al(3+) stimulated an electrical current carried by anion efflux across the plasma membrane in the Al(3+)-tolerant (ET8) and Al(3+)-sensitive (ES8) genotypes. This current occurred more frequently, had a greater current density, and remained active for longer in ET8 protoplasts than for ES8 protoplasts. The Al(3+)-activated current exhibited higher permeability to malate(2-) than to Cl(-) (P(mal)/P(Cl) > or = 2.6) and was inhibited by anion channel antagonists, niflumate and diphenylamine-2-carboxylic acid. In ET8, but not ES8, protoplasts an outward-rectifying K(+) current was activated in the presence of Al(3+) when cAMP was included in the pipette solution. These findings provide evidence that the difference in Al(3+)-induced malate efflux between Al(3+)-tolerant and Al(3+)-sensitive genotypes lies in the differing capacity for Al(3+) to activate malate permeable channels and cation channels for sustained malate release.

Aluminum↗
PubMed2001

The colposcopic impression. Is it influenced by the colposcopist's knowledge of the findings on the referral Papanicolaou smear?

OBJECTIVE: To determine whether the colposcopic impression is influenced by the colposcopist's knowledge of the referral Papanicolaou smear. STUDY DESIGN: Using a community hospital database, the accuracy of the colposcopic impression (accuracy = proportion of women with histology greater than cervical intraepithelial neoplasia [CIN] 2 that have colposcopic impressions of greater than CIN 2) when referral smears were atypical squamous cells of uncertain significance (ASCUS), atypical glandular cells of uncertain significance (AGUS) or low grade squamous intraepithelial lesion (LSIL) was compared to that when smears showed high grade squamous intraepithelial lesion (HSIL) or cancer. The analysis was repeated with a screening study database in which colposcopic impression was assigned without knowledge of the Papanicolaou smear. Univariate and logistic regression analysis of the second database determined the relative importance of size and grade of lesion and Papanicolaou result to the accuracy of the colposcopic impression. RESULTS: In the community database, colposcopic accuracy was 60/510 (12%) when smears were ASCUS, AGUS or LSIL and 77/132 (58%) when smears were HSIL or cancer (P < .001); in the second database, it was 2/19 (11%) when smears subsequently were reported as negative, ASCUS, AGUS or LSIL and 33/65 (54%) when smears were HSIL or cancer (P < .005). An accurate colposcopic impression was seen in 5/39 (13%) women with one-quadrant lesions, 8/18 (44%) with two-quadrant lesions and 23/27 (85%) with three- or four-quadrant lesions (P < .005). None of 19 women with smears reported as negative, ASCUS, AGUS or LSIL had lesions involving three or four quadrants of the cervix, while 27/65 (42%) women with smears reported as HSIL or cancer had such lesions (P < .005). With logistic regression, the more quadrants of the cervix involved, the more accurate the colposcopic impression. Once controlled for lesion size, there was no improvement when worst histologic grade or Papanicolaou smear result was considered. CONCLUSION: Through lesions greater than CIN 2 were more often overlooked when referral smears were negative, ASCUS, AGUS or LSIL than when they were HSIL or cancer, the real reason that the lesions were not detected by colposcopy was that they were small.

Clinical Competence↗
PubMed2001

[Pedicle graft of intestine seromuscular layer and skin graft for repair of abdominal wall defect].

OBJECTIVE: To explore an effective method to repair the abdominal wall defect. METHODS: From July 1996 to December 2000, 7 cases with abdominal wall defect were repaired by pedicle graft of intestine seromuscular layer and skin graft, among them, intestinal fistula caused by previous injury during operation in 4 cases, abdominal wall defect caused by infection after primary fistulization of colon tumor in 2 cases, abdominal wall invaded by intestinal tumor in 1 case. Exploratory laparotomy was performed under general anesthesia, the infective and edematous tissue around abdominal wall defect was gotten rid off, and the pathologic intestine was removed. A segment of intestine with mesentery was intercepted, and the intestine along the longitudinal axis offside mesentery was cutted, the mucous layer of intestine was scraped. The intestine seromuscular layer was sutured to the margin of abdominal wall defect, and grafted by intermediate split thickness skin. RESULTS: The abdominal wall wound in 6 cases were healed by first intention, but part of grafted skin was necrosed, and it was healed by second skin graft. No intestinal anastomotic leakage was observed in all cases. Followed up 1 to 2 years, there were no abdominal hernia or abdominal internal hernia. All the cases could normally defecate. The nutriture of all cases were improved remarkably. CONCLUSION: Pedicle graft of intestine seromuscular layer is a reliable method to repair abdominal wall defect with low regional tension, abundant blood supply and high successful rate.

Abdominal Muscles↗
PubMed2001

Expression, Purification and Functional Identification of Extracellular Part of Discoidin Domain Receptor 2.

Discoidin domain receptor 2 (DDR2) is a new type of receptor tyrosine kinases, and was thought to be involved in the metastasis of some tumors. Its ligand is fibrillar collagen. The activation of DDR2 induced by collagen mediates the over-expression of matrix metalloproteinase 1 (MMP-1) in cells. A specific inhibitor of DDR2 was necessary for the study of DDR2 function. Theoretically, a soluble receptor could possibly be used as specific inhibitor for the native receptor on cell membrane. In this report, a fragment (DB) of extracellular part of DDR2 was cloned and expressed for the use as potential inhibitor. This DB fragment corresponded to the polypeptide from the 23rd amino acid residue to the 293rd amino acid residue of DDR2. The fragment was amplified by RT-PCR from human lung cancer tissue, and the product was cloned into pMD18-T vector. After identification by sequence analysis, the fragment was sub-cloned into pGEX-4T-1 vector. Fusion protein of GST-DB was expressed in JM109 E.coli cells as expected and the soluble part accounted for about 13% of the total fusion protein. The soluble fusion protein was then purified with glutathione affinity resin, and GST-DB with purity of 86.1% was obtained. Competitive combination inhibitory test showed that the purified GST-DB inhibited the interaction between collagen II and DDR2 on the surface of RA synovial fibroblasts. Zymography analysis showed that the level of MMP-1 of both NIH 3T3 cell and RA synovial fibroblasts with collagen II-stimulation decreased after adding GST-DB fusion protein. The results indicated that the fusion protein GST-DB could inhibit the function of DDR2 on cells, and DDR2 might mediate collagen II-induced over-expression of MMP-1 in these cells.

Journal Article↗
PubMed2000

Fast activation of a time-dependent outward current in protoplasts derived from coats of developing Phaseolus vulgaris seeds.

An outward current that appeared to activate instantaneously in response to depolarising voltage pulses at low sampling frequencies predominated in the plasma membrane of ground-parenchyma protoplasts derived from coats of developing Phaseolus vulgaris L. (cv. Redland Pioneer) seeds. However, the outward current showed time-dependent activation when higher sampling frequencies were used to measure the current. Activation of the current was best described as a double-exponential time course with the fast and slow time constants being 1 and 20 ms, respectively. The current also exhibited a rapid deactivation that followed a double-exponential time course with time constants of approximately 2 and 30 ms, respectively. "Tail-current" analysis allowed us to show that this current exhibited a low selectivity between K- and Cl- (PK:Cl = 1.8). Such a fast-activating current may account for some of the reports of time-independent, instantaneous currents that have been observed in plasma membranes of plant cells digitised at low sampling frequencies. Therefore, when "instantaneous" currents appear it is advisable to characterise these currents using higher sampling frequencies with correspondingly higher filtering frequency cut-offs.

Fabaceae↗
PubMed2000

Suppression of adrenocorticotropic hormone release by stimulation of the nerve fibres in the anterior pituitary.

With the recent revelation of considerable peptidergic innervation of the anterior pituitary in several mammalian species, including man, it becomes imperative to elucidate the physiological significance of such a morphological entity. We addressed this issue by employing an anterior pituitary slice in vitro superfusion system coupled with electrical field stimulation. Anterior pituitary slices of 0.8 mm were perfused with Krebs-Ringer bicarbonate-bovine serum albumin buffer in a superfusion chamber for 30 min before electrical field stimulation. A square current of 30 mA, 10 Hz and 0.5 ms was then applied for 10 min. The perfusate was collected every 10 min and measured for adrenocorticotropic hormone (ACTH) by radio-immunoassay. It was found that under the experimental condition the basal release of ACTH was suppressed by electrical field stimulation of the nerve fibres in the anterior pituitary. Furthermore, vasopressin was added as a secretagogue. The suppression of ACTH by electrical field stimulation became even more marked. This is the first physiological evidence of the effect of stimulation of the nerve fibres innervating the anterior pituitary on its secretory activity.

Adrenocorticotropic Hormone↗
PubMed2000

Effluxes of solutes from developing seed coats of Phaseolus vulgaris L. and Vicia faba l.: locating the effect of turgor in a coupled chemiosmotic system.

Cells lining the developing seed coats of legumes efflux photosynthates (mostly sucrose) and salts (mostly of potassium) into the apoplast for uptake by the developing embryo. These effluxes increase transiently in response to an increase in turgor in the effluxing cells. Detached coats of developing seed of P. haseolus vulgaris and Vicia faba were used to study the effects of turgor on the rates of efflux, on the membrane potential difference and on the membrane pH difference, using a number of inhibitors and agents which might affect signal cascades involving cytoplasmic calcium concentration. Effluxes were measured by measuring the concentrations of solutes of interest in solution samples placed in halves of detached seed coats, the paired halves serving as control and treated sample where appropriate. It is shown that a number of substances affect sucrose and potassium effluxes differently, and that hypo-osmotic shock depolarizes the efflux cells and acidifies the cytoplasm (in P. vulgaris). It is concluded that sucrose and potassium effluxes, although both are increased by an increase in turgor, are affected by different signal pathways. Further, it is also concluded that the signal that increases the rates of both sucrose efflux (via sucrose-proton antiport) and proton pump acts directly on the antiporter rather than on the pump. There are interesting parallels and contrasts between these processes and those in plants such as the charophyte Lamprothamnium after hypo-osmotic shock.

Calcium↗
PubMed2000

Vaccinia virus F12L protein is required for actin tail formation, normal plaque size, and virulence.

Vaccinia virus gene F12L is shown to encode a 65-kDa protein that is synthesized early and late during infection and that is not modified by glycosylation. Computational sequence comparison revealed that related proteins are encoded by all sequenced chordopoxviruses. A virus deletion mutant lacking the F12L gene (vDeltaF12L) and a revertant virus with the F12L gene reinserted into the deletion mutant (vF12L-rev) were constructed and analyzed. A version of the F12L gene with a C-terminal amino acid tag derived from the influenza virus hemagglutinin and that is recognized by a monoclonal antibody was also inserted into the F12L locus of vDeltaF12L. Loss of the F12L protein reduced the formation of IMV 2-fold, but there was a dramatic (99.5%) reduction in actin tail formation, and the levels of cell-associated enveloped virus and extracellular enveloped virus were reduced 8- to 11-fold and 7-fold, respectively. Consistent with the lack of actin tail formation, vDeltaF12L produced a very small plaque. The vDeltaF12L virus was severely attenuated in vivo, such that a dose of vDeltaF12L 10,000-fold greater than the dose of wild-type virus that induced severe disease was unable to induce disease in mice infected intranasally.

Actins↗