Biomedical subjects

Z J Wang

Publications and source records attributed to Z J Wang.

At least 19 recordsLinked to original sources

PubMed2007

Selective removal of organochlorine pesticides (OCPs) from aqueous solution by triolein-embedded composite adsorbent.

A novel composite adsorbent (CA-T) was used for the selective removal of organochlorine pesticides (OCPs) from aqueous solution. The adsorbent was composed of the supporting activated carbon and the surrounding triolein-embedded cellulose acetate membrane. Scanning electron microscopy (SEM), N2 adsorption isotherms and fluorescence methods were used to characterize the physicochemical properties of CA-T. Triolein was perfectly embedded in the cellulose acetate membrane and deposited on the surface of activated carbon. The adsorbent was stable in water and no triolein leakage was detected during the test periods. Some organochlorine pesticides (OCPs), such as dieldrin, endrin, aldrin, and heptachlor epoxide, were used as model contaminants and removed by CA-T in laboratory batch experiments. The adsorption isotherm followed the Freundlich equation and the kinetic data fitted well to the pseudo-second-order reaction model. Results also indicated that CA-T appeared to be a promising adsorbent with good selectivity and satisfactory removal rate for lipophilic OCPs from aqueous solutions when present in trace amounts. The adsorption rate and removal efficiency for lipophilic OCPs were positively related to their octanol-water partition coefficients (log K(ow)). Lower residual concentrations of OCPs were achieved when compared to granular activated carbon (GAC).

Adsorption↗

PubMed2003

The transportation, time-dependent distribution of heavy metals in paddy crops.

Sixteen experimenmtal plots (5 m x 6 m = 30 m2) were designed with four different levels of heavy metals (HMs) concentration in soil. The concentrations of heavy metals in soils, and paddy plant during the different periods of growth were investigated. A relationship between the total HM content in plants and the HM level in soil was found for a wide range of concentrations. The exchangeable fraction of HMs extracted with 1 M MgCl2 solution according to Tessier's method increased correlation with the dosage of supplemented HMs, then decreased as time went on. The time-related variation of exchangeable HMs in soil demonstrated that the amount of effective HMs taken up by paddy differed at various growth phases. The amount of HMs accumulated in different parts of paddy followed the order of root > stem > grain, leaf. The transportation potential of the HMs in paddy in present study followed the order of Zn, Cr > Cd, Cu > Pb. The HM content in root, stem and leaf of paddy plant (dry weight) was low at time of seedling. The concentration in the root increased sharply at time of tillering, decreased thereafter. The concentrations in stem and leaf reached the highest at time of tillering, then decreased, while rose slightly at following time.

Biological Transport↗

PubMed2003

Chromosomal polymorphism of mandarin vole, Microtus mandarinus (Rodentia).

The mitotic and meiotic chromosomes of mandarin vole, Microtus mandarinus Milne-Edwards, from Shandong Province of China were analyzed by conventional, G- and C-banding and Silver-staining techniques. We detected chromosomal polymorphism in the vole, exhibiting diploid chromosome numbers 2n = 48-50 and variable morphology of the 1st pair, one medium sized telocentric pair and the X chromosomes. Four types of karyotypes were revealed in the population. According to banding analysis, there were pericentric inversion, Robertsonian fusion and translocation in M. mandarinus karyotype evolution. The X displayed two different morphologies, which could be explained by prericentric inversion and a telocentric autosome translocation.

Animals↗

PubMed2003

In vivo pyruvate detected by MR spectroscopy in neonatal pyruvate dehydrogenase deficiency.

We present a unique finding of an elevated level of pyruvate at 2.37 ppm revealed by in vivo MR spectroscopy of a female neonate. Low fibroblast pyruvate dehydrogenase (PDH) complex activity subsequently confirmed a diagnosis of PDH deficiency. Abnormalities of brain development consistent with PDH deficiency were also evident on fetal and postnatal MR images. To our knowledge, this is the first report of pyruvate being shown in vivo in a child and the first report of MR spectroscopy aiding in the diagnosis of inborn error in pyruvate metabolism before confirmation by conventional enzymatic testing. This finding has potential implications for earlier diagnosis in patients with defects in mitochondrial metabolism.

Abnormalities, Multiple↗

PubMed2002

Phosphine and methane generation by the addition of organic compounds containing carbon-phosphorus bonds into incubated soil.

Formation of phosphine and methane in anaerobic incubation systems was investigated under stirred and unstirred conditions. The PH3 and CH4 levels in the headspace, as well as the matrix-bound PH3 content in the stirred soil, significantly increased upon the addition of phosphonoacetic acid (P(O)(OH)2CH2COOH). Both the levels of matrix-bound PH3 and CH4 are positively correlated to the buffered dithionite fraction of reactive phosphorus in the soil samples, while a negative correlation was observed between matrix-bound PH3/CH4 levels and the reactive phosphorus fraction.

Bacteria, Anaerobic↗

PubMed2001

Synthesis and properties of 9,9-diarylfluorene-based triaryldiamines.

[reaction: see text] 9,9-Diaryl-2,7-dibromofluorene was synthesized by a triflic acid promoted Friedel-Crafts reaction. Introduction of diarylamino groups at its C2 and C7 positions by a Pd-catalyzed amination results in the formation of a novel class of triaryldiamines. The 9,9-diaryl substituents at the central linkage play a less important role in the photophyscial properties but affect the oxidation potential and improve the morphological stability of these new triarylamines.

Journal Article↗

PubMed2001

Aromatase (Cyp19) expression is up-regulated by targeted disruption of Dax1.

DAX-1 [dosage-sensitive sex reversal, adrenal hypoplasia congenita (AHC) critical region on the X chromosome, gene 1] is an orphan nuclear receptor that represses transcription by steroidogenic factor-1 (SF-1), a factor that regulates expression of multiple steroidogenic enzymes and other genes involved in reproduction. Mutations in the human DAX1 gene (also known as AHC) cause the X-linked syndrome AHC, a disorder that is associated with hypogonadotropic hypogonadism also. Characterization of Dax1-deficient male mice revealed primary testicular defects that included Leydig cell hyperplasia (LCH) and progressive degeneration of the germinal epithelium, leading to infertility. In this study, we investigated the effect of Dax1 disruption on the expression profile of various steroidogenic enzyme genes in Leydig cells isolated from Dax1-deficient male mice. Expression of the aromatase (Cyp19) gene, which encodes the enzyme that converts testosterone to estradiol, was increased significantly in the Leydig cells isolated from mutant mice, whereas the expression of other proteins (e.g., StAR and Cyp11a) was not altered. In in vitro transfection studies, DAX-1 repressed the SF-1-mediated transactivation of the Cyp19 promoter but did not inhibit the StAR or Cyp11a promoters. Elevated Cyp19 expression was accompanied by increased intratesticular levels of estradiol. Administration of tamoxifen, a selective estrogen-receptor modulator, restored fertility to the Dax1-deficient male mice and partially corrected LCH, suggesting that estrogen excess contributes to LCH and infertility. Based on these in vivo and in vitro analyses, aromatase seems to be a physiologic target of Dax-1 in Leydig cells, and increased Cyp19 expression may account, in part, for the infertility and LCH in Dax1-deficient mice.

Animals↗

PubMed2001

Proton magnetic resonance spectroscopy of brain metabolites in galactosemia.

Brain edema may occur in infants with galactosemia and has been associated with accumulation of galactitol. Proton magnetic resonance spectra were obtained from 12 patients (four newly diagnosed neonates and eight patients on galactose-restricted diets, age range 1.7-47 years) and control subjects to measure brain galactitol levels in vivo and correlate them with urinary galactitol excretion. The results demonstrate that a markedly elevated brain galactitol level may be present only in newborn infants with galactosemia who exhibit massive urinary galactitol excretion.

Adolescent↗

PubMed2001

Low allicin release from garlic supplements: a major problem due to the sensitivities of alliinase activity.

Most garlic supplements are standardized on allicin potential and are enteric-coated to prevent gastric acid inactivation of the allicin-producing enzyme, alliinase. To determine whether these products release the claimed amount of allicin under simulated gastrointestinal conditions, USP dissolution method 724A for drug release was applied to all 24 known brands of enteric-coated tablets. It was found that nearly all brands employed effective coatings and that they met their claims for allicin potential when crushed and suspended in water. However, all brands except one gave low dissolution allicin release, with 83% of the brands releasing less than 15% of their potential. The low allicin release was found to be due to both impaired alliinase activity, mostly caused by tablet excipients, and to slow tablet disintegration, which also impairs alliinase activity. Only when tablets had high alliinase activity and disintegrated rapidly did they show high allicin release. The ability of USP 724A to estimate allicin release in vivo was validated by monitoring breath levels of the allicin metabolite, allyl methyl sulfide. In conclusion, garlic powder supplements should no longer be standardized on allicin potential, but rather on dissolution allicin release.

Antioxidants↗

PubMed2001

Allicin release under simulated gastrointestinal conditions from garlic powder tablets employed in clinical trials on serum cholesterol.

The failure of five recent clinical trials to show significant reduction in elevated serum cholesterol by a single brand of allicin-standardized garlic powder tablets is in contrast to many prior positive studies with the same brand. The hypocholesterolemic activity of garlic is mainly due to allicin, a compound that is produced by the acid-sensitive garlic enzyme, alliinase, only after tablet consumption. Therefore, the allicin-releasing ability of ten lots of these tablets--manufactured over the same years that the positive and negative clinical trials were conducted (1989-1997)--was determined under simulated gastrointestinal dissolution conditions, as defined by U.S. Pharmacopeia Method 724A. It was found that the older lots were more resistant to acid-disintegration (2.5 h vs. 1.3 h, P < 0.001) and that they released three times as much allicin (44% vs. 15 % of their potential, P < 0.001) as the newer lots. A second brand of tablets employed in a recent negative trial released no detectable amount of allicin, while a third set of tablets with high allicin release was used in a trial that gave positive effects. Hence, the persons involved in the recent negative clinical trials probably received considerably less allicin than did those in the older positive studies, possibly accounting for much of the discrepancy in the outcomes. In conclusion, clinical trials using garlic powder tablets to assess any effect of garlic that might be related to allicin, as most are, cannot be considered valid for garlic when the trial shows no effect, unless the expected allicin release from the tablets has at least been determined under standardized drug release conditions (USP 724A).

Cholesterol↗

PubMed2001

An Oral Health Survey in Southern China, 1997: background and methodology.

Relatively limited information is available about the oral health in the Guangdong Province of Southern China, the closest neighbor to Hong Kong. The study intended to explore the oral health status, knowledge, attitudes, and dental care utilization in the Guangdong population as a basis for formulating strategies for oral health prevention and treatment. Through multi-stage stratified and quota-sampling, individuals from urban as well as rural communities were selected (5- to 6-; 12-; 35- to 44-; and 65- to 74-year-olds; total N = 6251). Structured interviews and clinical examinations were performed. Inter-examiner reliability was high (kappa = 0.60-0.96). Samples of community water were taken for fluoride assessment. Overall, the sample surveyed was acceptably representative of the population, with some under-representation of rural residents and agricultural workers. Re-weighting was performed in appropriate analyses. The data analysis model used in the Second International Collaborative Study was used as a guide for the present data analysis. This approach has not previously been used on a Mainland Chinese population.

Adolescent↗

PubMed2001

Oral health knowledge, attitudes, and practices of Chinese adults.

Only recently have behavioral aspects been taken into consideration in oral health studies in China; thus, relevant information on perceptions in adult Chinese about oral health care is inadequate. In 1996-97, a large-scale oral epidemiological study was conducted in Southern China. Among its objectives were to describe the oral health knowledge, attitudes, and practices of the urban and rural adults living in Southern China and to analyze the influence of selected demographic and socio-economic factors. From 8 urban and 8 rural communities in Guangdong Province, 1,573 35- to 44-year-olds and 1,515 65- to 74-year-olds were sampled. Specially trained interviewers from the staff of local government or hospitals conducted face-to-face structured interviews. Almost all of the middle-aged and more than 90% of the dentate elderly surveyed claimed that they brushed their teeth every day and used toothpaste during toothbrushing, but awareness about fluoride content was lacking. The respondents had poor oral health knowledge but positive attitudes toward oral health, providing a basis for more community-based oral health education programs, especially targeting adults who are less-well-educated and have fewer socio-economic advantages.

Adult↗

PubMed2001

Utilization of dental services in Southern China.

A population's utilization of dental services is an important parameter in oral health care planning, which has rarely been studied in China. The objectives of this report were to describe the dental service utilization pattern of middle-aged and elderly Chinese and to analyze the influence of selected variables on the use of dental services. A Guangdong Province population of 1,573 35- to 44-year-olds and 1,515 65- to 74-year-olds recruited from urban and rural communities was interviewed in their local dialect. It was found that 23% of the middle-aged and 24% of the elderly subjects had visited a dentist within the preceding year. The two most commonly cited reasons for not having seen a dentist for at least 3 years were: no perceived need, and no serious dental problems. Among subjects who had visited a dentist within 3 years, the 3 most commonly received treatments were: fillings, extractions, and dental prostheses. Furthermore, a logistic regression analysis showed that women, subjects who lived in urban areas, were better educated, were wealthier, and had better oral health knowledge were more likely to be a recent dental service user. In conclusion, dental service utilization among the adult Southern Chinese was found to be low, problem-driven, and influenced by some socio-economic factors.

Adult↗

PubMed2001

Sertoli cell-specific rescue of fertility, but not testicular pathology, in Dax1 (Ahch)-deficient male mice.

DAX1 is an orphan member of the nuclear hormone receptor superfamily of transcription factors. Our recent characterization of Dax1 (Ahch)-deficient male mice revealed a primary testicular defect resulting in hypogonadism and sterility. The progressive degeneration of the germinal epithelium, independent of abnormal gonadotropin and testosterone production, suggested an intrinsic loss of Dax1 function in the Sertoli cells. To test this hypothesis, we assessed the effect of Sertoli cell-specific expression of a human DAX1 (AHC) transgene driven using the promoter of the Müllerian inhibiting substance (MIS) gene. The MIS-DAX1 transgene partially rescued the mutant phenotype of the Dax1-deficient male mice. Although testicular morphology remained abnormal, fertility was restored to levels matching that of wild-type littermates. Examination of several markers of sperm fertilizing capability revealed significant improvements in MIS-DAX1-rescued mice. Epididymal sperm count and sperm motility were greater in 12-week-old rescued mice than in age-matched Dax1-deficient mice. The ability of sperm to undergo an immediate acrosome reaction was impaired in Dax1-deficient animals, and sperm from Dax1-deficient mice fertilized only 8.2 +/- 6.8% of eggs in vitro, significantly less than rescue (67.8 +/- 19.1%) and wild-type (88.9 +/- 3.9%) sperm. These results indicate that Dax1 expression in Sertoli cells is adequate to overcome crucial thresholds related to sperm production and function. However, the failure to completely rescue the testicular pathology of Dax1-deficient mice suggests that Dax1 expression in other somatic cells is essential for normal testicular development.

Acrosome Reaction↗

PubMed2001

Time-dependent apoptotic development and pro-apoptotic genes expression in rat heart after myocardial infarction.

We investigated the apoptotic development and apoptotic-related gene expression after myocardial infarction (MI) at different time points in the current study. Bax gene expression was increased at 12 h after MI and peaked at 24 h. Fas gene started to over-express at 12 h after MI as well but it reached maximum at 72 h. In the MI groups, strongest staining of apoptosis was detected in rats 3 days post operation. Our results demonstrate that apoptotic development after MI is time dependent in the ischemic area and there could be some linkage with the over expression of angiotensin II receptors post MI.

Animals↗

PubMed2001

The effect of fulvic acid on the dose effect of selenite on the growth of wheat.

The effect of fulvic acid on the dose effect of selenite has been studied by using the hydroponics culture of wheat in the presence of selenite and fulvic acid (FA). The bioavailability of Se was investigated by 5 morphological end points and 12 biological and biochemical end points at different phases of growth of wheat seedling and seed germination. The "platform" of the dose effect observed indicates that the presence of FA can have both the beneficial effects and antagonists on the toxicity of Se to a certain extent.

Benzopyrans↗

PubMed2001

MR spectroscopy in pediatric neuroradiology.

MR spectroscopy of the pediatric brain now has entered the clinical arena as a result of enhanced technology, complementary new sequences, and proof of clinical utility. Armed with a knowledge of the variation in metabolite concentrations over time, with myelination and brain growth, proton MR spectroscopy can be helpful in differential diagnosis, management, and prognostication of pediatric disease processes. Although other molecules can be interrogated, hydrogen proton spectroscopy is the mainstay. The development of multiplanar techniques, performed in a time-efficient fashion, has enabled more robust spectra to be obtained from larger volumes of brain, permitting spatial localization of different metabolites, such as lactate. With the introduction of gene therapy and other new interventions, a noninvasive tool such as MR spectroscopy may prove to be invaluable.

Brain↗

PubMed2001

[Effects of nutrition condition on pcDNA3-HBS plasmid DNA production].

To investigate the effects of nutrition condition on plasmid DNA production, Escherichia coli JM109 containing plasmid pcDNA3S-HBA was grown in different culture media. Results show that carbon source, nitrogen source affected plasmid DNA yield significantly. Glucose and peptone was selected, since they were preferable to other investigated carbon source and nitrogen source. In M9P medium, the appropriate concentration of(NH4)2SO4 was important for plasmid DNA production, Gly, Asp, Gln were formulated into the M9G medium because they served as the nitrogen donors for nucleotides synthesis. With addition of 1.2 g/L Asp, 1.0 g/L Gln and 0.4 g/L Gly into M9G medium, plasmid DNA yield was 25 mg/L after 20 h culture. Foreign nucleotides distinctively affected plasmid DNA production. With addition of 0.4 g/L nucleosides mixture of thymidine and cytidine(moles fraction of thymidine:cytidine = 1:1) into M9P medium, plasmid DNA yield was 35 mg/L.

Amino Acids↗