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Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 253 records · Page 14Linked to original sources

Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for management of distal ureteral calculi.

PURPOSE: We compared the efficacy of shock wave lithotripsy and ureteroscopy for treatment of distal ureteral calculi. MATERIALS AND METHODS: A total of 64 patients with solitary, radiopaque distal ureteral calculi 15 mm. or less in largest diameter were randomized to treatment with shock wave lithotripsy (32) using an HM3 lithotriptor (Dornier MedTech, Kennesaw, Georgia) or ureteroscopy (32). Patient and stone characteristics, treatment parameters, clinical outcomes, patient satisfaction and cost were assessed for each group. RESULTS: The 2 groups were comparable in regard to patient age, sex, body mass index, stone size, degree of hydronephrosis and time to treatment. Procedural and operating room times were statistically significantly shorter for the shock wave lithotripsy compared to the ureteroscopy group (34 and 72 versus 65 and 97 minutes, respectively). In addition, 94% of patients who underwent shock wave lithotripsy versus 75% who underwent ureteroscopy were discharged home the day of procedure. At a mean followup of 21 and 24 days for shock wave lithotripsy and ureteroscopy, respectively, 91% of patients in each group had undergone imaging with a plain abdominal radiograph, and all studies showed resolution of the target stone. Minor complications occurred in 9% and 25% of the shock wave lithotripsy and ureteroscopy groups, respectively (p value was not significant). No ureteral perforation or stricture occurred in the ureteroscopy group. Postoperative flank pain and dysuria were more severe in the ureteroscopy than shock wave lithotripsy group, although the differences were not statistically significant. Patient satisfaction was high, including 94% for shock wave lithotripsy and 87% for ureteroscopy (p value not significant). Cost favored ureteroscopy by $1,255 if outpatient treatment for both modalities was assumed. CONCLUSIONS: Ureteroscopy and shock wave lithotripsy were associated with high success and low complication rates. However, shock wave lithotripsy required significantly less operating time, was more often performed on an outpatient basis, and showed a trend towards less flank pain and dysuria, fewer complications and quicker convalescence. Patient satisfaction was uniformly high in both groups. Although ureteroscopy and shock wave lithotripsy are highly effective for treatment of distal ureteral stones, we believe that HM3 shock wave lithotripsy, albeit slightly more costly, is preferable to manipulation with ureteroscopy since it is equally efficacious, more efficient and less morbid.

Adult↗

Effect of Cr(VI) exposure on sperm quality: human and animal studies.

The semen status of male workers occupationally exposed to hexavalent chromium(VI) was investigated. Sperm counts from exposed workers were 47.05+/-2.13 x 10(6)/ml and those from control group 88.96+/-3.40 x 10(6)/ml. Sperm motility decreased from 81.92+/-0.41% for the control group to 69.71+/-0.93% for the exposed workers. The levels of zinc, lactate dehydrogenase (LDH), and lactate dehydrogenase C4 isoenzyme (LDH-x) in seminal plasma for the exposed workers were 1.48+/-0.07 micromol/ml, 1.05+/-0.02 x 10(3) U, and 0.47+/-0.01 x 10(3) U, respectively, which were significantly lower than those of 5.72+/-0.15 micromol/ml, 1.49+/-0.02 x 10(3) U, and 0.78+/-0.15 x 10(3) U for the control group, respectively. Follicle stimulating hormone (FSH) (7.34+/-0.34 x 10(-3) IU/ml) in serum from the exposed workers was significantly higher than that (2.41+/-0.08 x 10(-3) IU/ml) from the control group. On the other hand, there were no significant differences in semen volume, semen liquefaction time, luteinizing hormone (LH) level in serum, and Cr concentration in both serum and seminal plasma between the exposed workers and the control group. Feeding Cr(VI) to rats significantly reduced the epididymal sperm counts from 87.40+/-3.85 x 10(6)/g epididymis in control group to 21.40+/-1.20 x 10(6)/g epididymis at a CrO(3) dose of 10 mg/kg body weight and to 17.48+/-1.04 x 10(6)/g epididymis at a CrO(3) dose of 20 mg/kg body weight. Exposure of rats to Cr(VI) also significantly increased the sperm abnormality from 2.75+/-0.06% in the control group to 6.68+/-0.32% in the exposed group at a CrO(3) dose of 10 mg/kg body and to 7.6+/-0.15% at a CrO(3) dose of 20 mg/kg body weight. In exposed rats, there was visible disruption in germ cell arrangement near the walls of the seminiferous tubules. The diameters of seminiferous tubules in exposed rats were smaller. These results suggest that occupational exposure to chromium(VI) leads to alteration of semen status and may affect the reproductive success of exposed workers.

Animals↗

Polymorphic markers in the SRD5A2 gene and prostate cancer risk: a population-based case-control study.

It has been suggested that the activity of the steroid 5alpha-reductase type II enzyme (encoded by the SRD5A2 gene) may be associated with prostate cancer risk and that population differences in this enzyme's activity may account for part of the substantial racial/ethnic disparity in prostate cancer risk. To provide etiological clues, we evaluated the relationships of four polymorphic markers in the SRD5A2 gene, specifically, A49T (a substitution of threonine for alanine at codon 49), V89L (a substitution of leucine for valine at codon 89), R227Q (a substitution of glutamine for arginine at codon 227), and a (TA)n dinucleotide repeat, with prostate cancer risk in a population-based case-control study in China, a population with the lowest reported prostate cancer incidence rate in the world. Genotypes of these four markers were determined from genomic DNA of 191 incident cases of prostate cancer and 304 healthy controls using PCR-based assays, and serum androgen levels were measured in relation to these genotypes. All study subjects had the wild-type AA genotype of the A49T marker, and 99% had the RR genotype of the R227Q marker. For the V89L marker, prevalences of the LL, VV, and VL genotypes among controls were 35%, 21%, and 45%, respectively. Compared with men with the VV genotype, those with the LL genotype had a statistically nonsignificant 12% reduced risk (odds ratio = 0.88, 95% confidence interval, 0.53-1.47). In addition, men with the LL genotype had significantly higher serum levels of testosterone and significantly lower serum levels of 5alpha-androstane-3alpha,17beta-diol glucuronide than men with other genotypes. Men heterozygous for the (TA)0 allele of the (TA)n marker had a modest, statistically nonsignificant risk reduction (odds ratio = 0.67; 95% confidence interval, 0.39-1.12) compared with men homozygous for the (TA)0 allele, along with significantly higher serum dihydrotestosterone levels. The observed V89L genotype prevalences and the association between V89L genotypes and serum androgen levels support the hypothesis that genotypes associated with lower levels of 5alpha-reductase activity are more common in low-risk populations. Although we found no statistically significant associations of these SRD5A2 polymorphisms with prostate cancer risk, a small effect of these markers cannot be ruled out because of the rarity of certain marker genotypes. Larger studies are needed to further clarify the role of these markers and to elucidate whether genetic diversity of the SRD5A2 gene, alone or in combination with other susceptibility genes, can help explain the large racial/ethnic differences in prostate cancer risk.

Adult↗

A survey of the dietary nutritional composition of centenarians.

OBJECTIVE: To make a survey of the nutritional composition of the diets of centenarians. METHODS: Thirty-four centenarians were selected as subjects. Retrospective surveys were made on the variety and amounts of food consumed and their nutritional composition. Physical examinations with laboratory tests such as cardiograms, ultrasonic B rays, and blood, urine and hair tests were performed. Neutron activation testing was done on hair content. The transmission turbidimetric method was used to measure apolipoprotein content. RESULTS: The main food of the centenarians showed the characteristics of low calories, protein and fat but high fiber and mineral content. Laboratory results showed that the content of the elements of Cu, Se and Mn in hair was higher (P < 0.01). Zn was normal. The apoA1/apoB100 ratio was higher than in the control group (P < 0.01), and total cholesterol (TC) was lower than in the control group (P < 0.01). CONCLUSIONS: The variety of diet and its nutritional composition may be the main factors influencing not only the content of elements in body, but also the levels of apoA1 and apoB100, which may be helpful in preventing arteriosclerosis and forming and maintaining immunity. The diet of these centenarians might aid in preventing cardiovascular and cerebrovascular diseases and malignant tumors.

Aged↗

Oral squamous cell cancer risk in relation to alcohol consumption and alcohol dehydrogenase-3 genotypes.

Heavy alcohol consumption, particularly in combination with cigarette smoking, increases the risk of oral squamous cell carcinoma (OSCC). Alcohol dehydrogenase 3 (ADH3) converts ethanol to acetaldehyde, which is a suspected oral carcinogen. The ADH3*1 allele is associated with increased conversion of ethanol to acetaldehyde, but whether the risk of OSCC is increased among ADH3*1 carriers, or whether the risk of OSCC attributable to alcohol consumption is modified by ADH3 genotype is unclear from previous studies. We examined the association between ADH3 genotypes, alcohol consumption, and OSCC risk in a population-based study of 333 cases and 541 controls from the state of Washington. The distribution of ADH3 genotypes was similar among cases and controls: ADH3*1/*1: 32.7% cases, 36.5% controls; ADH3*1/*2: 49.0% cases, 43.1% controls: ADH3*2/*2: 18.3% cases, 20.3% controls. The age-, sex-, and race-adjusted odds ratios (OR), relative to ADH3*2/*2 carriers, were as follows: ADH*1/*1: OR, 1.0 [95% confidence interval (CI) = 0.7, 1.5]; and ADH3*1/*2: OR, 1.3 (95% CI = 1.0, 1.8). We modeled the risk of OSCC associated with alcohol consumption as modified by ADH3 genotype adjusting for age, sex, race, and cigarette smoking. Among ADH3*2 homozygotes, the risk of OSCC increased 5.3% (2.1-8.5%) with each additional alcoholic drink/week, compared with 2.5% (1.5-2.6%) and 1.2% (0.0-2.4%) among persons carrying the ADH3*1/*2 and ADH3*1/*1 genotypes, respectively. These data suggest that the ADH3*2 allele confers increased susceptibility to the effect of alcohol on OSCC risk in our population.

Adult↗

[Interspecific association of dominant species in Betula luminifera natural forest communities of Shaowu, Fujian Province].

chi 2 test with 2 x 2 contingency table and Jaccard indices shows that the interspecific association of 16 dominant species in Betula luminifera communities of Shaowu, Fujian Province was of little significant level with few exceptions. The relationships between B. luminifera and Phyllostachys pubescens, and B. luminifera and Alniphyllum fortunei were significantly positive, showing that there was a high association degree between B. luminifera and Schima superba, B. luminifera, and Castanea henrgi, and B. luminifera and Pinus massoniana based on Jaccard indices.

Trees↗

[Characteristics of nitrobenzene containing wastewater catalytic oxidation degradation by Fenton reagent].

Through the alteration of the concentration of catalyst and oxidant, the rulers and dynamics of nitrobenzene oxidized by Fenton reagent in different concentrations were studied. The correlativity of the reaction time and relatively remain nitrobenzene was analyzed by the unitary linear regress equation. The result of the analysis proves that the coefficient was over the critical constant. The oxidation of nitrobenzene by Fenton reagent was in conformity with first-order dynamics model and the reaction rate constant was got at the same time. The idea, using the complex of Fe as the catalyst replacing Fe2+ in the Fenton Reaction, not only got a higher reaction velocity and efficiency, but also had a distinct exclusive to the degradation of nitrobenzene. The remove velocity of nitrobenzene was improved from 17.48 mg/(L.min) to 71.22 mg/(L.min), the remove rate in 5 minutes was from 9.74% to 91.79%. The nonhomogeneous catalyst made by the artificial zeolite with Fe-complex adsorbed had the same catalyzing behavior. In addition, ultraviolet radiation can also improves the Fenton reaction to some degree. These research works could demonstrate the good application potentiality of Fenton reagent in treating wastewater.

Catalysis↗

[Allogeneic peripheral blood stem cell transplantation for 3 patients with beta-thalassemia major and 1 patient with congenital idiopathic haemolytic anemia].

OBJECTIVE: To examine the feasibility of allogeneic peripheral blood stem cell transplantation (Allo-PBSCT) for the hereditary haemolytic anemia (HHA). METHODS: Allo-PBSCTs were performed on 3 patients with beta-thalassemia major and 1 patient with congenital idiopathic haemolytic anemia by the HLA-identical siblings' donors or 1 locus-mismatch parent. The harvested stem cell contained nucleated cells (4.7-14.4) X 10(8)/kg recipient weight, CD(34) (+) CD(38)(-) cells(4.8-32.9) X 10(6)/kg and colony-forming-unit-granulocyte-macrophages (CFU-GM)(3.22-9.8) X 10(5)/kg. The conditioning regimen consisted of busulfan, cyclophosphamide, melphalan, thiotepa, fludarabine and antithymocyte globulin (ATG). RESULTS: All patients were engrafted and accomplished with the acute graft-versus-host disease (aGVHD). A patient had the controlled chronic GVHD. Three patients are survivals with ex-anemia; their Hb levels have been maintaining normality without transfusion. One died of the hepatic veno-occlusive disease. CONCLUSION: Allo-PBSCT is an effective and a new way to treat beta-thalassemia major and congenital idiopathic haemolytic anemia.

Anemia, Hemolytic, Congenital↗

[Transcatheter arterial embolization in intractable postpartum hemorrhage].

OBJECTIVE: To asses the value of transcatheter arterial embolization treatment in intractable postpartum hemorrhage. METHODS: Fourteen patients of postpartum hemorrhage failed to the drugs treatment were performed transcatheter arterial embolization (TAE). Superselective catheterization to the bilateral uterial arteries or anterior branches of internal iliac arteries was carried out after intubation to single-side femoral artery by Seldinger's technique. When the catheter tip was proved in right place by digital substraction angiography (DSA) techniques, antibiotic solution was poured into arteries and then the arterial embolization with gelfoam particles was followed. RESULTS: All the patients were performed TAE successfully. The duration of TAE was 30-50 minutes [mean (41.8 +/- 6.4) minutes]. Bleeding was found in DSA mostly as diffuse intrauterine flow outward sign from one side or both side of uterial artery branches. After one time of TAE, the vaginal bleeding of all patients was stopped in 3-10 minutes [mean (6.1 +/- 3.6) minutes]. The follow-up showed that all patients had normal menstrual periods in 2-60 months and no serious complications were found. CONCLUSION: With the characteristic of fast homeostasis and less complications, TAE was proved to be an effective method for intractable postpartum hemorrhage.

Adult↗

The association between PPP1R3 gene polymorphisms and type 2 diabetes mellitus.

OBJECTIVE: To detect the relationship between the polymorphism of the glycogen-targeting regulatory subunit of the skeletal muscle glycogen-associated protein phosphatase 1 (PPP1R3) gene and type 2 diabetes by case-control study. METHODS: We genotyped the PPP1R3 gene Asp905Tyr polymorphism and a common 3'-untranslated region AT (AU)-rich element (ARE) polymorphism in 101 type 2 diabetic patients and 101 controls by oligonucleotide ligation assay (OLA) and polyacrylamide gel elecrophoresis, respectively. RESULTS: Subjects with Tyr/Tyr genotypes whose body mass index (BMI) < 25 were used as the reference group. Those whose BMI > or = 25 with Asp905 had a 3.66-fold increase (95% CI: 1.48-9.06, P = 0.005) in type 2 diabetes risk. No association was found between 3'UTR ARE polymorphism and type 2 diabetes mellitus (OR = 1.15; 95% CI: 0.62-2.14, P = 0.65). CONCLUSION: A joint effect between the Asp905 and BMI increases the risk of type 2 diabetes, and Asp905Tyr and ARE polymorphism of PPP1R3 gene are not the major diabetogenic gene variants in Chinese population.

AT Rich Sequence↗

The role of physiologically based toxicokinetic models in biologically based risk assessment.

Biologically-based cancer risk assessment relies on mathematical models that represent the toxicokinetics and toxicodynamics of the xenobiotic in the body. Physiologically-based toxicokinetic (PBTK) models are used as a tool for predicting the target tissue dose of a xenobiotic from different routes of exposure, extrapolating from high doses to low doses and extrapolating between species. This paper reviews the role of PBTK models and their limitations in biologically-based risk assessment.

Animals↗

[Umbilical cord blood transplantation (UCBT) in thalassemia children].

OBJECTIVE: To evaluate the efficacy of allo-UCBT in thalassemia children. METHODS: Five patients with beta-thalassemia major (genotypes were homozygote of beta41-42, beta654 and double heterozygosities of beta41-42/beta654, beta41-42/-28, beta654/-28, respectively) were treated by allo-UCBT. The median age was 3 year and ten month old (31/2 - 7 2/12). Four donor-recipient pairs were HLA-identical and one 1 locus mismatch. The patients received a median UCB nucleated cells (NC) of 5.5 x 10(7)/kg body weight [range (4.7 - 7.7) x 10(7)/kg] and CD(34)(+)CD(38)(-) cells 2.8 x 10(5)/kg [range (0.6 - 4.5) x 10(5)/kg] and CFU-GM 1.09 x 10(5)/kg [range (0.24 - 230.00) x 10(5)/kg]. The conditioning regimen consisted ofbusalphan 16 - 20 mg/kg, cyclophosphamide 180 - 200 mg/kg, horse antithymocyte globulin (ATG) 90 mg/kg or rabbit anti-lymphocyte globulin (ALG) 25 mg/kg and melphalan of 90 mg/m(2) was added to four cases. Cyclosporine A (CsA) alone was administered in 3 cases, and a combination of CsA and methotrexate in the other 2 cases. RESULTS: Four cases were engrafted, but one rejected and recurred thalassemia state at day 60 past UCBT. One case had autologous reconstitution. The reconstitutions were found in all patients with neutrophils 0.5 x 10(9)/L at day 19 (14 - 22), platelets > 20 x 10(9)/L at day 37 (21 - 63). Two cases developed grade I and II acute GVHD respectively. None developed chronic GVHD. Three patients survived disease-freely (survival with ex-thalassemia state). The median follow-up was 18 months, the probability of survival was 100%. CONCLUSION: Allo-UCBT could reconstitute hematopoiesis with low frequency and mild grade of GVHD. It is an effective treatment for thalassemia.

Child↗

[Studies on calluses induced from various explants of Cistanche deserticola].

Calluses were induced from various explants (flower, stem, bud and squama) of Cistanche deserticola Y.C.Ma and compared with each other. The result showed that the inducement rate of ovary and stem were higher than that of other explants which the inducement time was short and the characters of calluses were good. The effect of basal culture medium added hormone on callus reproduction was also studied. The result showed that B5 culture medium added 1 mg/L IBA and 2 mg/L 6-BA was optimal.

Cistanche↗

[Measurement of waveguide depth in proton-exchanged LiNbO3 by infrared absorption spectroscopy].

A novel method for determining proton-exchanged LiNbO3 waveguide depth by infrared absorption spectroscopy was proposed. The method overcomes the shortcoming that the conventional prism-coupling + IWKB technique is only applicable to the multimode waveguides. For the commonly used single-mode waveguides, however, it is helpless. The experimental results indicated that this method has good accuracy.

Absorptiometry, Photon↗

Activation of mitogen-activated protein kinase pathways induces antioxidant response element-mediated gene expression via a Nrf2-dependent mechanism.

Antioxidant response element (ARE) regulates the induction of a number of cellular antioxidant and detoxifying enzymes. However, the signaling pathways that lead to ARE activation remain unknown. Here, we report that the expression of mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase kinase kinase 1 (MEKK1), transforming growth factor-beta-activated kinase (TAK1), and apoptosis signal-regulating kinase (ASK1) in HepG2 cells activated the ARE reporter gene, whereas the expression of their dominant-negative mutants impaired ARE activation by the chemicals sodium arsenite and mercury chloride. Coexpression of downstream kinases, MAP kinase kinase 4, MAP kinase kinase 6, and c-Jun NH(2)-terminal kinase-1, but not MAP kinase kinase 3 and p38, augmented ARE activation by MEKK1, TAK1, and ASK1. The coexpression of a basic leucine zipper transcription factor Nrf2 but not c-Jun also greatly enhanced the activation of reporter gene by MEKK1, TAK1, and ASK1; however, a dominant-negative mutant of Nrf2 (NF-E2-related factor 2) blocked this event. Furthermore, when overexpressed, MEKK1, TAK1, and ASK1 induced the expression of heme oxygenase-1, a gene regulated by ARE, and the cotransfection with the dominant-negative mutant of Nrf2 abolished the induction. Taken together, these results suggest that MAP kinase pathways that are activated by MEKK1, TAK1, and ASK1 may link chemical signals to Nrf2, leading to the activation of ARE-dependent genes.

Antioxidants↗

Regulation of glut1 mRNA by hypoxia-inducible factor-1. Interaction between H-ras and hypoxia.

Oncogenic transformation and hypoxia both induce glut1 mRNA. We studied the interaction between the ras oncogene and hypoxia in up-regulating glut1 mRNA levels using Rat1 fibroblasts transformed with H-ras (Rat1-ras). Transformation with H-ras led to a substantial increase in glut1 mRNA levels under normoxic conditions and additively increased glut1 mRNA levels in concert with hypoxia. Using a luciferase reporter construct containing 6 kilobase pairs of the glut1 promoter, we showed that this effect was mediated at the transcriptional level. Promoter activity was much higher in Rat1-ras cells than in Rat1 cells and could be down-regulated by cotransfection with a dominant negative Ras construct (RasN17). A 480-base pair (bp) cobalt/hypoxia-responsive fragment of the promoter containing a HIF-1 binding site showed significantly higher activity in Rat1-ras cells than in Rat1 cells, suggesting that Ras might mediate its effect through HIF-1 even under normoxic conditions. Consistent with this, Rat1-ras cells displayed higher levels of HIF1-alpha protein under normoxic conditions. In addition, a promoter construct containing a 4-bp mutation in the HIF1 binding site showed lower activity in Rat1-ras cells than a construct with an intact HIF1 binding site. The activity of the latter construct but not the former could be down-regulated by RasN17, supporting the importance of the HIF1 binding site in regulation by Ras. The phosphatidylinositol 3-kinase inhibitor LY29004 down-regulated glut1 promoter activity and mRNA levels under normoxia and also decreased HIF1alpha protein levels in these cells. Collectively these results indicate that H-Ras up-regulates the glut1 promoter, at least in part, by increasing HIF-1alpha protein levels leading to transactivation of promoter through the HIF-1 binding site.

Animals↗

Delaying caspase activation by Bcl-2: A clue to disease retardation in a transgenic mouse model of amyotrophic lateral sclerosis.

Molecular mechanisms of apoptosis may participate in motor neuron degeneration produced by mutant copper/zinc superoxide dismutase (mSOD1), the only proven cause of amyotrophic lateral sclerosis (ALS). Consistent with this, herein we show that the spinal cord of transgenic mSOD1 mice is the site of the sequential activation of caspase-1 and caspase-3. Activated caspase-3 and its produced beta-actin cleavage fragments are found in apoptotic neurons in the anterior horn of the spinal cord of affected transgenic mSOD1 mice; although such neurons are few, their scarcity should not undermine the potential importance of apoptosis in the overall mSOD1-related neurodegeneration. Overexpression of the anti-apoptotic protein Bcl-2 attenuates neurodegeneration and delays activation of the caspases and fragmentation of beta-actin. These data demonstrate that caspase activation occurs in this mouse model of ALS during neurodegeneration. Our study also suggests that modulation of caspase activity may provide protective benefit in the treatment of ALS, a view that is consistent with our recent demonstration of caspase inhibition extending the survival of transgenic mSOD1 mice.

Actins↗