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Biomedical subjects

S Cheng

Publications and source records attributed to S Cheng.

At least 73 records · Page 4Linked to original sources
PubMed2001

Characterization of a 4-methylbenzoate-degrading methanogenic consortium as determined by small-subunit rDNA sequence analysis.

A methanogenic consortium that degrades 4-methylbenzoate (MBA) as the sole carbon and energy source was successfully enriched in an upflow anaerobic sludge bed bioreactor and studied. Electron microscopic observation showed that long rods with a distinct collar feature resembling Desulfomonile tiedjei rods were the predominant population, and that these rods formed a close spatial orientation with Methanobrevibacter-like bacteria. In addition, thin filaments and bamboo-shaped filaments that highly resembled the acetoclastic Methanosaeta were also frequently observed. A 16S rDNA clone library was constructed for the domain Bacteria, and 20 sequence types or operational taxonomic units (OTUs) were found out of 139 clones screened. Phylogenetic analysis classified these 20 nearly full-length OTUs into the delta (50.3% of total clones) and gamma (4.3%) subdivisions of the division Proteobacteria, the green non-sulfur bacteria subdivision I (7.2%), Cytophagales (7.2%), Planctomycetes (5.7%), gram-positive low G + C group (8.6%), candidate divisions OP8, OP10 and OP11 (9.3%), and a novel candidate division MBA1 (7.2%) that had an interdivisional sequence similarity less than 75%. However, only 3 OTUs had a sequence similarity higher than 90% to known isolates or environmental 16S rDNA clones, suggesting that the microbial community was diversified and largely unidentified. In particular, those 8 OTUs found in the delta-Proteobacteria were either clustered into novel groups or showed a low sequence similarity to closely related bacteria. It is highly possible that the delta-Proteobacteria were the long rods with a distinct collar feature observed microscopically, and together with the methanogens were mainly responsible for the syntrophic degradation of MBA. The unique and novel microbial populations identified explained the requirement of a long start-up period of up to 426 d for the MBA-degrading consortium.

Journal Article↗
PubMed2001

Calcaneal bone mineral and ultrasound attenuation in male athletes exposed to weight-bearing and nonweight-bearing activity. A cross-sectional report.

BACKGROUND: To determine if the expected differences in bone mineral content/density of the calcaneus among male athletic groups that undertake weight-bearing and nonweight-bearing activity are also apparent for bone quality as assessed by quantitative ultrasound (QUS) attenuation. METHODS EXPERIMENTAL DESIGN: cross-sectional. SETTING: a University research laboratory. PARTICIPANTS: we studied 30 young men: 10 Finnish national level jumpers whose training incorporates repeated impacts to the heel, 10 aquatics athletes whose skeletons are exposed to nonweight-bearing activity, and 10 sedentary men matched for age and body weight. MEASURES: bone mineral content (BMC, g x cm(-1)), areal bone mineral density (BMDa; g x cm(-2)) and presumed volumetric BMD (BMDv, g x cm(-3)) was measured by single energy photon absorption (SPA). Broadband ultrasound attenuation (BUA using Fourier spectral estimation and UBI-4 using Burg spectral estimation, both in db/MHz) was assessed by a new QUS device (QUS-1TM, Metra Biosystems). RESULTS: There was no difference in years of sport specific training or total training time per week between athlete groups. BMC, BMDa and BMDv were significantly different among groups (p=0.0001) with jumpers being higher than aquatics athletes and controls. BMC of jumpers was 52% and 39% higher than controls and aquatics athletes, respectively, while the corresponding values for BMDv were 34% and 28%. However, BUA values were not significantly different (p=0.10) among groups nor was UBI-4 (p=0.03; jumpers values were 7% and 6% higher than aquatics athletes and controls, respectively). CONCLUSIONS: These cross-sectional results indicate that bone mineral content and density of the calcaneus are substantially higher in jumpers than individuals engaged in nonweight-bearing or regular weight-bearing activity. However, parameters assessed by QUS attenuation are not markedly different, which suggests that bone quality properties may not be as responsive as that of bone mineral content/density to habitual skeletal loading.

Adult↗
PubMed2001

Effects of hormone replacement therapy and high-impact physical exercise on skeletal muscle in post-menopausal women: a randomized placebo-controlled study.

An age-related decline in muscle performance is a known risk factor for falling, fracture and disability. In women, a clear deterioration is observed from early menopause. The effect of hormone replacement therapy (HRT) in preserving muscle performance is, however, unclear. This trial examined the effects of a 12-month HRT and high-impact physical exercise regimen on skeletal muscle in women in early menopause. A total of 80 women aged 50-57 years were assigned randomly to one of four groups: exercise (Ex), HRT, exercise+HRT (ExHRT) and control (Co). The exercise groups participated in a high-impact training programme. The administration of HRT (oestradiol/noretisterone acetate) or placebo was carried out double-blind. Knee extension torque and vertical jumping height were evaluated. Lean tissue cross-sectional area (LCSA) and the relative proportion of fat within the muscle compartment were measured for the quadriceps and lower leg muscles. The ExHRT group showed significant increases in knee extension torque (8.3%) and vertical jumping height (17.2%) when compared with the Co group (-7.2%). Vertical jumping height also increased after HRT alone (6.8%). The LCSA of the quadriceps was increased significantly in the HRT (6.3%) and ExHRT (7.1%) groups when compared with the Ex (2.2%) and Co (0.7%) groups. Lower leg LCSA was also increased in the ExHRT group (9.1%) when compared with the Ex (3.0%) and Co (4.1%) groups. In addition, the increase in the relative proportion of fat in the quadriceps in the Co group (16.6%) was significant compared with those in the HRT (4.9%) and ExHRT (-0.6%) groups. Thus, in post-menopausal women, muscle performance, muscle mass and muscle composition are improved by HRT. The beneficial effects of HRT combined with high-impact physical training may exceed those of HRT alone.

Analysis of Variance↗
PubMed2001

Open donor, laparoscopic donor and hand assisted laparoscopic donor nephrectomy: a comparison of outcomes.

PURPOSE: In experienced hands laparoscopic surgery has been shown to be safe for procuring kidneys for transplantation that function identically to open nephrectomy controls. While searching for a safer and easier approach to laparoscopic donor nephrectomy, hand assisted laparoscopic techniques have been added to the surgical armamentarium. We compare allograft function in patients with greater than 1-year followup who underwent open donor (historic series), classic laparoscopic and hand assisted laparoscopic nephrectomy. MATERIALS AND METHODS: The charts of 48 patients who underwent open donor, laparoscopic donor or hand assisted laparoscopic nephrectomy were reviewed. Only patients with greater than 1-year followup and complete charts were included in our study. Of these patients 34 underwent consecutive laparoscopic live donor nephrectomy and 14 underwent open donor nephrectomy. Mean patient age plus or minus standard deviation (SD) was 36.5 +/- 8.4 years for donors and 29 +/- 17 for recipients at transplantation (range 13 months to 69 years). In the laparoscopic group 11 patients underwent the transperitoneal technique, and 23 underwent hand assisted laparoscopic nephrectomy. RESULTS: Total operating time was significantly reduced with the hand assisted laparoscopic technique compared with classic laparoscopy, as was the time from skin incision to kidney removal and warm ischemic time. Average warm ischemic time plus or minus SD was 3.9 +/- 0.3 minutes for laparoscopic nephrectomy and 1.6 +/- 0.2 for hand assisted laparoscopy (p <0.05). Long-term followup of serum creatinine levels revealed no significant differences among the 3 groups. Comparison of those levels for recipients of open nephrectomy versus laparoscopic and hand assisted laparoscopic techniques revealed p values greater than 0.5. No blood transfusions were necessary. Complications included adrenal vein injury in 1 patient, small bowel obstruction in 2, abdominal hernia at the trocar site in 1 and deep venous thrombosis in 1. CONCLUSIONS: Classic laparoscopic donor and hand assisted laparoscopic donor nephrectomies appear to be safe procedures for harvesting kidneys. The recipient graft function is similar in the laparoscopic and open surgery groups.

Adolescent↗
PubMed2001

[Relationship between eutrophication control and reservoir operation].

Choosing Miyun Reservoir as a research background, the spatial distribution characteristics of water quality in the reservoir were analyzed, and the relationship between reservoir operation and-eutrophication control was discussed. With the assistance of water quality model and the monitored data, measures that wiping off the nutrients combined with the flood prevention operation was proposed. At last, the feasibility of the measure was also discussed.

Phosphorus↗
PubMed2001

[Degradation of the herbicide dicamba under strictly anaerobic conditions].

Degradation of the herbicide dicamba was assayed under methane-producing condition using a coastal wetland soil as an inoculum. Benzene ring 14C labeled dicamba was employed and degradative process proceeds through demethoxylation yielding 3,6-dichlorosalicylic acid as the predominant intermediate. The data showed that the degradation rate of dicamba by the enrichment culture achieved 64%, 91% and 95% after 7, 16 and 27 days of incubation, respectively; only small quantities of CO2(0.74%) and CH4(0.11%) were recovered with insignificant radioactivity. The benzene ring of dicamba was not cleavaged to a significant extent. Future cleaning up of dicamba contaminated environment may require an effective bioremediation techniques.

Anaerobiosis↗
PubMed2001

Genetic influences on lipid metabolism trait variability within the Stanislas Cohort.

The contribution of 17 polymorphisms within 13 candidate genes on lipid trait variability was investigated by a multiplex assay in 772 men and 780 women coming for a health checkup examination. The studied genes were APOE, APOB, APOC3, CETP, LPL, PON, MTHFR, FGB, GpIIIa, SELE, ACE, and AGT. We found that APOB-Thr71Ile, APOE-(112/158), APOC3-1100C/T, and SELE-98G/T polymorphisms had a significant effect on lipid traits (P < or = 0.001 to P < or = 0.01). Genetic effects accounted for 3.5-5.7% of variation in apolipoprotein B (apoB)-related traits among men, and for 5.7-9.0% among women. The contribution of APOE polymorphism on apoB-related traits variability was two to three times more important in women than in men. We found suggestive evidence for interactive effects between genetics and age, smoking status, and oral contraceptives. Increase of LDL-cholesterol and apoB concentrations with age was stronger among the epsilon4 carriers in women, and apolipoprotein A-I (apoA-I) concentration decreased with age in epsilon4 male carriers. The effect of epsilon2 allele on LDL-cholesterol was more important in the oral contraceptive users. In nonsmokers only, the APOC3-1100C allele in women was related to lower apoB-related traits concentrations, and in men to higher apoA-I and HDL-cholesterol concentrations. In conclusion, this work, in addition to the reinforcement of the already known associations between APOB, APOE, and APOC3 genes and lipids, leads to new perspectives in the complex relationships among genes and environmental factors. The newly observed relationships between E-selectine gene and lipid concentrations support the hypotheses of multiple metabolic pathways contributing to the complexity of lipids variability.

Adult↗
PubMed2001

[The protective effects of Zn-metallothionein on severely scalded rats inflicted by oxygen free radicals].

OBJECTIVE: To investigate the protective effects of metallothionein (MT) on severely scalded rats inflicted by oxygen free radicals after delayed resuscitation. METHODS: Wistar rats inflicted by 30% TBSA III degree scalding injury were taken as the model. Fifty-Six rats were randomly divided into four groups, i.e. normal control, delayed resuscitation, MT treated and VitC treated groups. The changes in superoxide dismutase (SOD) and malondialdehyde (MDA) contents in plasma and subeschar edematous fluid were determined at 24 and 48 postburn hours with traditional indirect detecting method and electron spin resonance (ESR). Pathomorphological examination was simultaneously carried out for cardiac, hepatic, renal and intestinal samples. Plasma biochemical indices were determined at the same time. RESULTS: In delayed resuscitation group, SOD content decreased and the MDA contents increased in plasma and subeschar fluid obviously, with remarkable changes in the pathomorphology of all the internal organs and the blood biochemical indices. But in MT treating group, SOD content increased (P < 0.05) with decreased content of MDA (P < 0.05) and the pathomorphology and blood biochemical indices improved significantly when compared with those in delayed resuscitation group and VitC treatment group. CONCLUSION: MT treatment might be beneficial in the management of severely scalding rats infliced by oxygen free radicals.

Alanine Transaminase↗
PubMed2001

[Cloning, sequencing of beagle E-selectin genomic DNA and comparison of it with other species].

OBJECTIVE: Selectins are a group of members of Cell Adhesion Molecular family; they play very important roles in inflammation and neovascularization. The aim of this study is to clone, sequence Beagle E-selectin genomic DNA and make homogeneous analyses to compare it with those of other animals. METHODS: Twelve fragments of genomic DNA of Beagle E-selectin were obtained by PCR, and the 12 fragments were cloned in T-vector. At last, the genomic DNA sequences of Beagle E-selectin were obtained through gene sequencing, assembling and base calling, and the gene structure was analyzed. RESULTS: The sequence of Beagle E-selectin genomic DNA that contained the whole open reading box was acgured. The results of homogeneous analyses showed a great extent of E-selectin gene homology among human, porcine and dog. CONCLUSION: The demonstration of a large extent of the gene homology has substantiated in this connection the important roles of E-selectin in transplantation immunity and neoplasm development.

Animals↗
PubMed2001

[Loss of heterozygosity on chromosome 9p13-23 in microdissected laryngeal squamous cell carcinoma by microsatellite analysis].

OBJECTIVE: Loss of heterozygosity (LOH) studies indicate that allelic loss associated with the development of head and neck of squamous cell carcinoma occurs most frequently at 9p21-22. However, the target of chromosome 9p21-22 loss has been the source of significant debate. A putative tumor suppressor gene, p16, has been identified at the 9p21 location, but genetic alterations of p16 located in this region are unusual. To refine the hot spots of LOH on chromosome 9p13-23 will be helpful to find other putative tumor suppressor genes in laryngeal squamous cell carcinoma. METHODS: The sections of paraffin-embedded tumor tissues were microdissected to enrich for neoplastic cells. LOH on 9p13-23 was analyzed in a set of 42 paired blood and tumor samples using polymerase chain reaction (PCR) with 13 highly polymorphic microsatellite markers. RESULTS: Of the 42 total tumors, 41(97.6%) showed LOH in at least one of the microsatellite markers tested at the chromosome 9p13-23 region. The most frequently deleted marker was D9S162 with in 17 of 19 (89.5%) informative samples. The marker D9S171, which is located in 9p21, had LOH detected in 12 of 15 informative cases (80.0%). LOH at the D9S1748 marker (closest to the p16 gene locus) was detected in 18 of 36 informative cases (50.0%). Fine deletion mapping also revealed two minimal regions of LOH encompassing markers D9S161-D9S171 at 9p21 and IFNA-D9S162 at 9p22-23. CONCLUSION: These findings imply the high frequency of LOH at 9p13-23 in laryngeal squamous cell carcinoma and the presence of at least two as yet unidentified tumor suppressor genes in 9p13-23 region. Those putative tumor suppressor genes may become inactivated during the progression of the laryngeal squamous cell carcinoma.

Adult↗
PubMed2000

Mice with a targeted mutation in the thyroid hormone beta receptor gene exhibit impaired growth and resistance to thyroid hormone.

Patients with mutations in the thyroid hormone receptor beta (TRbeta) gene manifest resistance to thyroid hormone (RTH), resulting in a constellation of variable phenotypic abnormalities. To understand the molecular basis underlying the action of mutant TRbeta in vivo, we generated mice with a targeted mutation in the TRbeta gene (TRbetaPV; PV, mutant thyroid hormone receptor kindred PV) by using homologous recombination and the Cre/loxP system. Mice expressing a single PV allele showed the typical abnormalities of thyroid function found in heterozygous humans with RTH. Homozygous PV mice exhibit severe dysfunction of the pituitary-thyroid axis, impaired weight gains, and abnormal bone development. This phenotype is distinct from that seen in mice with a null mutation in the TRbeta gene. Importantly, we identified abnormal expression patterns of several genes in tissues of TRbetaPV mice, demonstrating the interference of the mutant TR with the gene regulatory functions of the wild-type TR in vivo. These results show that the actions of mutant and wild-type TRbeta in vivo are distinct. This model allows further study of the molecular action of mutant TR in vivo, which could lead to better treatment for RTH patients.

Alleles↗
PubMed2000

Effects of urea and sodium hydroxide on the molecular weight and conformation of alpha-(1-->3)-D-glucan from Lentinus edodes in aqueous solution.

The weight-average molecular weight (Mw) and intrinsic viscosity ([eta]) of the alpha-(1-->3)-D-glucan (L-FV-II) from Lentinus edodes in 0.5 and 1.0 M NaOH aqueous solution containing urea, were studied by light scattering and viscometry. The Mw value of the glucan decreased with increase of the urea and NaOH concentration. A strong intermolecular hydrogen bonding confers water-insolubility on the glucan, but NaOH and especially urea, broke this hydrogen bonding leading to enhanced water-solubility. Use of 1.0 M urea-1.0 M NaOH as solvent broke not only intermolecular hydrogen bonds but also partial covalent bonds of the alpha-glucan in aqueous solution, resulting in a decrease of Mw and [eta]. The urea and NaOH concentrations, storage time with stirring, and mode of preparation of the polysaccharide in aqueous solution significantly affected the determination of Mw and [eta]. The dependences of specific rotation and fluorescence emission ratio of a probe on urea concentration showed that a change in the molecular conformation of the alpha-glucan in 0.5 M NaOH aqueous solution containing urea occurred in the range 0.4-0.6 M urea. The 0.5 M urea-0.5 M NaOH aqueous solution is a suitable solvent for the glucan, and the Mw and [eta] values obtained were 5.21 x 10(5) and 148 cm3 g(-1), respectively. Degradation of the glucan was obvious after storage for 15 months.

Dose-Response Relationship, Drug↗
PubMed2000

Recovery of Penaeus monodon from functional anaemia after exposure to sublethal concentration of nitrite at different pH levels.

Tiger shrimp Penaeus monodon (14.79+/-0.19 g) which had been exposed individually to 0.72 mM nitrite at pH 6.8, 8.2 and 9.8 after 3, 6, 12, 24 and 48 h were examined for the water nitrite concentration, hemolymph nitrite, oxyhemocyanin, protein and osmolality levels. Same parameters were examined for shrimp depurated in nitrite-free water after 3, 6, 12 and 24 h following 48 h exposure to nitrite. In the nitrite-exposed test, nitrite influx, hemolymph nitrite and osmotic differential (medium osmolality - hemolymph osmolality) increased with exposure time, and were higher at pH 6.8, whereas water nitrite concentration, oxyhemocyanin, protein, ratio of oxyhemocyanin to protein and hemolymph osmolality decreased with exposure time and were lower at pH 6.8. In the depuration test, water nitrite concentration increased with depuration time, and was higher at pH 6.8, whereas, hemolymph oxyhemocyanin, ratio of oxyhemocyanin to protein and hemolymph osmolality increased with depuration time and were higher at pH 9.8. Hemolymph nitrite decreased with depuration time, and was 2.52, 2.19 and 0.24 µmol ml(-1) after 6 h at pH 6.8, 8.2 and 9.8, respectively. Nitrite entry is considered to occur mainly via the form of nitrous acid (HNO(2)) in water uptake. The fact that the hemolymph nitrite decreased to non-detectable level with 72-88% recovery of oxyhemocyanin after 24 h depuration suggests an occurrence of reductase for nitrite-exposed shrimps.

Journal Article↗
PubMed2000

Hormone binding induces rapid proteasome-mediated degradation of thyroid hormone receptors.

The thyroid hormone 3,3',5-triiodo-l-thyronine (T3) is essential for growth, differentiation, and development. Its biological activities are mediated by T3 nuclear receptors (TRs). At present, how T3 regulates TR proteins and the resulting functional consequences are still unknown. Immunofluorescence analyses of endogenous TR in the growth hormone-producing GC cells showed that the T3-induced rapid degradation of TR was specifically blocked by lactacystin, a selective inhibitor of the ubiquitin-proteasome degradation pathway. Immunoblots demonstrated that the transfected TRbeta1 was ubiquitinated and that the ubiquitination was T3 independent. Studies with a series of truncated TRbeta1 showed that the hormone-binding domain was sufficient for the T3-induced rapid degradation of TRbeta1 by the proteasome degradation pathway. T3 also induced rapid degradation of TRbeta2 and TRalpha1. In contrast, the stability of the non-T3-binding TRalpha2 and naturally occurring TRbeta1 mutants that do not bind T3 was not affected by T3 treatment, indicating that hormone binding to receptor was essential for the degradation of the wild-type receptors. In the presence of proteasome protease inhibitors, the levels of both total and ubiquitinated TRbeta1 protein increased, yet T3-dependent transcriptional activation and the expression of the growth hormone gene were diminished, suggesting that proteasome-mediated degradation played a novel role in modulating transcriptional activation by TR. The present study reveals a role of T3 in modulating the functions of TR by regulating its receptor level via the ubiquitin-proteasome degradation pathway.

Animals↗
PubMed2000

Expression of thyroid hormone receptors is disturbed in human renal clear cell carcinoma.

Human renal clear cell carcinoma (RCCC) accounts for up to 2% of human cancers. To find out if thyroid hormone (T3) and its receptors (TRs) play a role in tumorigenesis of RCCC, the expression of TRs was evaluated on mRNA and protein level. It was found that TRalpha (both alpha1 and alpha2) mRNA amount was significantly decreased in tumors while compared with healthy kidney tissue, and this decrease was deepest in G1 (well differentiated) RCCCs. In contrast, TRalpha1 protein was 1.6x overexpressed in tumors. TRbeta1 mRNA amount was overexpressed in 30% and significantly decreased in 70% of examined tumors. On the protein level, TRbeta1 amount was 1.7x lower in tumors than in healthy controls.

Adenocarcinoma, Clear Cell↗
PubMed2000

Changes in work practice after a respiratory health survey among welders in New Zealand.

AIMS: To assess changes in work practice among eight New Zealand engineering sites, following a study of occupational respiratory symptoms in welders two years previously. METHODS: In 1996, we found that an acute decrease in lung function was more common in welders working without local exhaust ventilation. Findings were reported back to management, study participants and the media. Two years later we re-visited the eight welding sites. RESULTS: Of the eight engineering sites, two had local exhaust ventilation present in both Study 1 and Study 2, one site had installed local exhaust ventilation in part of the site since Study 1 and one site had moved to larger premises. The remaining four sites had no exhaust ventilation or change to the workplace between studies. Five welders (12.8%) used respiratory protection in both Study 1 and Study 2, seven welders (18%) used respiratory protection in Study 1 but not Study 2, four welders (10.3%) did not have respiratory protection in Study 1 but did in Study 2 and nine welders (23.1%) did not use respiratory protection at all in Study 1 or Study 2. CONCLUSION: Further effort is required to ensure that such studies lead to significant improvements in the work environment.

Air Pollutants, Occupational↗
PubMed2000

Measuring gene-specific nucleotide excision repair in human cells using quantitative amplification of long targets from nanogram quantities of DNA.

We have been developing a rapid and convenient assay for the measurement of DNA damage and repair in specific genes using quantitative polymerase chain reaction (QPCR) methodology. Since the sensitivity of this assay is limited to the size of the DNA amplification fragment, conditions have been found for the quantitative generation of PCR fragments from human genomic DNA in the range of 6-24 kb in length. These fragments include: (1) a 16.2 kb product from the mitochondrial genome; (2) 6.2, 10.4 kb, and 15.4 kb products from the hprt gene, and (3) 13.5, 17.7, 24.2 kb products from the human beta-globin gene cluster. Exposure of SV40 transformed human fibroblasts to increasing fluences of ultraviolet light (UV) resulted in the linear production of photoproducts with 10 J/m(2) of UVC producing 0.085 and 0.079 lesions/kb in the hprt gene and the beta-globin gene cluster, respectively. Kinetic analysis of repair following 10 J/m(2) of UVC exposure indicated that the time necessary for the removal of 50% of the photoproducts, in the hprt gene and beta-globin gene cluster was 7.8 and 24.2 h, respectively. Studies using lymphoblastoid cell lines show very little repair in XPA cells in both the hprt gene and beta-globin locus. Preferential repair in the hprt gene was detected in XPC cells. Cisplatin lesions were also detected using this method and showed slower rates of repair than UV-induced photoproducts. These data indicate that the use of long targets in the gene-specific QPCR assay allows the measurement of biologically relevant lesion frequencies in 5-30 ng of genomic DNA. This assay will be useful for the measurement of human exposure to genotoxic agents and the determination of human repair capacity.

Cell Line↗