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Biomedical subjects

C Wang

Publications and source records attributed to C Wang.

At least 73 records · Page 4Linked to original sources
PubMed2004

Binding of dodecyltrimethylammonium bromide to pH-responsive nanocolloids containing cross-linked methacrylic acid-ethyl acrylate copolymers.

The binding of dodecyltrimethylammonium bromide (DoTab) to cross-linked methacrylic acid-ethyl acrylate (MAA-EA) copolymers with various MAA/EA molar ratios at different degrees of neutralization (alpha) was quantitatively studied using isothermal titration calorimetry, dynamic light scattering, surfactant selective electrode, and electrophoresis techniques. The surfactant binds to the polymers at all degrees of neutralization, but via different mechanisms. When alpha is sufficiently high, the binding is primarily electrostatic interaction between the surfactant and ionized polymer chains, which is reinforced by the micellization of electrostatically bound surfactant molecules. The saturation takes place at charge ratio ([DoTa(+)]/[ approximately COO(-)]) close to 1, indicating that the binding is a one-to-one charge neutralization between the cationic surfactant headgroups and anionic carboxylate sites of the polymers. When alpha is low, the binding of DoTab to the unneutralized polymers is driven by the hydrophobic interaction. The onset of hydrophobic binding takes place at DoTab concentration as low as 0.01 mM in 0.05 wt % polymer solution, where the saturation occurs at C(DoTab) approximately 0.19 mM and the amount of bound surfactant is approximately 0.09 mmol of DoTab/(g of polymer) at saturation concentration. The binding results in the formation of the polymer-surfactant complex. For the polymer with low MAA/EA molar ratio, the complex coagulates at a higher DoTab concentration that leads to phase separation; however, for polymers with high MAA/EA molar ratio, the complex remains dispersed and the mixture is stable even at high DoTab concentration.

Acrylates↗
PubMed2004

Exploring children's conceptions of smoking addiction.

Tobacco addiction is a major health problem for both adults and young people--between 20 and 60% of adolescents are dependent on nicotine and more than two-thirds who attempt to quit experience withdrawal symptoms. Yet, anti-smoking efforts targeted at children emphasize primary prevention and ignore addiction education, which is generally considered relevant only to adult smoking and cessation efforts. This study reports children's concepts of smoking and addiction from interviews with 32 Western Australian boys and girls, aged 9-10 years, all non-smokers. Results suggest children's concepts of smoking addiction may influence attitudes toward smoking trials. Children who thought addiction happened immediately were committed to never smoke at all. Others who thought addiction happened after several cigarettes expressed intentions to experiment. These children believed they could avoid addiction by smoking less than the number of cigarettes that caused addiction. Children who defined addiction as 'liking' or 'enjoying the taste of cigarettes' believed they could avoid being 'hooked' as long as they managed to avoid enjoying the experience. Recent findings that children can get 'hooked' within a few days of smoking highlight the importance of addiction strategies targeted at children, particularly in relation to influencing intentions to experiment with smoking.

Australia↗
PubMed2004

Correlation between thyroid hormone status and hepatic hyperplasia and hypertrophy caused by the peroxisome proliferator-activated receptor alpha agonist Wy-14,643.

BACKGROUND: The metabolic inhibitor rotenone inhibits hepatocellular proliferation and the incidence of liver cancer resulting from exposure to the PPARalpha agonist Wy-14,643, via unknown mechanisms. Since the absence of thyroid hormones diminishes hepatomegaly, an early biomarker for the hepatocarcinogenicity induced by PPARalpha agonists, this study was undertaken to investigate whether rotenone might interference with the ability of Wy-14,643 to alter the animal thyroid status. METHODS: Male B6C3F1 mice were given Wy-14,643 (100 ppm), rotenone (600 ppm) or a mixture of both, in the feed for 7 days. Bromodeoxyuridine (BrDU), marker of cell replication, was delivered through subcutaneously implanted osmotic mini-pumps. At the end of the experiment, sera were collected and corticosterone and thyroid hormone levels were measured by solid-phase radioimmunoassay kits. In addition, liver tissue samples were stained immunohistochemically for BrDU to determine percentages of labeled cells. Further, cell surface area was determined from images generated by a Zeiss Axioplan microscope equipped with a plan Neofluar x40 0.75 na objective. Tracings of individual hepatocyte perimeters were then analyzed and cell-surface areas were calculated using MicroMeasure FL-4000. RESULTS: Wy-14,643 caused a significant increase in liver weights, hepatocyte BrDU labeling index (LI), and hepatocyte surface area. In animals which received both Wy-14,643 and rotenone simultaneously, all of these effects were significantly less pronounced compared with mice that received Wy-14,643 alone. Rotenone alone decreased liver weights, LI and surface area. The Free Thyroid Index (FTI), which provides an accurate reflection of the animal's thyroid status, was 5.0 +/- 0.3 in control mice. In animals exposed to rotenone, these values decreased to 2.0 +/- 0.9, but in animals which received Wy-14,643, levels increased significantly to 7.7 +/- 0.9. FTI values decreased to 3.4 +/- 0.8 in mice receiving both rotenone and Wy-14,643. CONCLUSION: A strong correlation was observed between the animal thyroid status and both, hepatocyte proliferation (r2 = 0.62), and hepatocyte surface area (r2 = 0.83). These results support the hypothesis that the thyroid status of the animal plays a role in PPARalpha-induced hepatocellular proliferation and liver cell enlargement. Both these events are known to contribute to the expression of liver cancer in response to the activation of PPARalpha.

Journal Article↗
PubMed2004

Salt-assisted and salt-suppressed sol-gel transitions of methylcellulose in water.

The effects of various salts on the sol-gel transition of aqueous methylcellulose (MC) solutions have been studied systematically by means of a micro differential scanning calorimeter. It was found that the heating process was endothermic while the cooling process was exothermic for both MC solutions with and without salts. The addition of salts did not change the patterns of gelation and degelation of MC. However, the salts could shift the sol-gel transition and the gel-sol transition to lower or higher temperatures from a pure MC solution, depending on the salt type. These opposite effects were termed the salt-assisted and salt-suppressed sol-gel transitions. Either the salt-assisted transition or the salt-suppressed sol-gel transition was a function of salt concentration. In addition, each salt was found to have its own concentration limit for producing a stable aqueous solution of MC at a given concentration of MC, which was related to the anionic charge density of the salt. Cations were proved to have weaker effects than anions. The "salt-out strength", defined as the salt effect per mole of anion, was obtained for each anion studied. The thermodynamic mechanisms involved in the salt-assisted and salt-suppressed sol-gel transitions are discussed.

Anions↗
PubMed2004

Is diabetes an independent risk factor for mortality after myocardial infarction? The ARIC (Atherosclerosis Risk in Communities) Surveillance Study.

We investigated the age-, gender- and race-specific 1-year case fatality rates of diabetic and non-diabetic individuals with a myocardial infarction. Data were obtained from the Atherosclerosis Risk in Communities (ARIC) Surveillance Study, which monitors both hospitalized myocardial infarction and coronary heart disease (CHD) deaths in residents aged 35-74 years in four communities in the USA. The study population comprised 3242 hospitalized myocardial infarctions (HMIs) in diabetic subjects and 9826 HMIs in non-diabetic individuals between 1987 and 1997. Age-adjusted and gender- and race-specific odds ratios (OR) for 1-year case fatality comparing diabetic to non-diabetic patients were 2.0 (95% CI, 1.6-2.4) for white men and 1.4 (95% CI, 1.1-1.8) for white women. Further adjustment for severity of HMI, history of previous MI, stroke and hypertension, and therapy variables showed significantly higher case fatality in white diabetic men than in non-diabetic white men (OR=1.5; 95% CI, 1.2-1.9), but no significant association in the other race-gender groups. The age-adjusted odds of out of hospital death was significantly higher among white diabetic men (OR=1.7; 95% CI, 1.2-2.3), white women (OR=2.3; 95% CI, 1.4-3.8), and African-American women (OR=2.9; 95% CI, 1.5-5.9) as compared to their non-diabetic counterparts. In conclusion, diabetes is an independent factor for mortality within one year following a myocardial infarction among white men, and following out-of hospital coronary death in white men and women and in African-American women. It is possible that these differences could be explained, at least in part, by a less than optimal medical management of the high cardiovascular risk profile of these patients after hospital discharge.

Arteriosclerosis↗
PubMed2004

Scanning for MODY5 gene mutations in Chinese early onset or multiple affected diabetes pedigrees.

Mutation of HNF-1beta gene has been reported in early onset diabetes or MODY families and this gene has been defined as MODY5 gene. The aim of our study was to examine whether HNF-1beta mutation contribute to early onset or multiple affected diabetes pedigrees in Chinese. Molecular scanning of HNF-1beta gene promoter region, nine exons and flanking introns was performed in 154 unrelated probands from early onset and multiple affected diabetes Chinese pedigrees. The family members of probands with mutations or variants and 58 nondiabetics were also examined. Clinical examinations of renal morphology, renal function and beta-cell function were performed in the HNF-1beta gene mutation carriers and family members. Mutation of HNF-1beta gene causing the substitution S36F was found in two subjects of an early onset diabetic family. One carrier has early onset diabetes, renal function impairment and renal cyst, while the other has impaired glucose tolerance only. This is the first case of MODY5 gene mutation diabetes found in the Chinese. Three HNF-1beta variants were identified and no significant differences in allele frequencies for these variants were detected between the nondiabetic and diabetic groups. Nucleotide 66 of intron 8 of HNF-1beta gene was G in the Chinese population rather than A as noted in the GenBank sequence. These results suggest that HNF-1beta gene mutations may be associated with nondiabetic renal dysfunction and diabetes in Chinese, but they are responsible for only a small percentage of early onset or multiple affected diabetes pedigrees including MODY.

Adenine↗
PubMed2004

Blockade of N-methyl-D-aspartate receptors by phencyclidine causes the loss of corticostriatal neurons.

Perinatal administration of the N-methyl-Dd-aspartate (NMDA) receptor antagonist phencyclidine (PCP) has been reported to produce regionally selective apoptotic cell death in the frontal cortex. The development of certain behavioral abnormalities following PCP treatment suggested that extracortical regions such as the striatum also could be affected. In this study, perinatal PCP treatment caused a marked reduction in striatal, but not hippocampal, staining for polysialic acid-neural cell adhesion molecule (PSA-NCAM), an NMDA-regulated molecule important in synaptogenesis. In order to isolate striatal influences to the cortex, this investigation was continued in vitro using corticostriatal slices. For these experiments we cultured coronal corticostriatal slices from postnatal day 7 rats. After 4 days in vitro, PCP was added for 48 h and then washed out for 24 h before harvesting the tissue. Similar to what was observed in vivo, we found that PCP treatment results in a marked reduction in striatal staining for PSA-NCAM. No change was observed in the mature form of NCAM. In striatal synaptoneurosomes, immunoblot analysis confirmed that the levels of PSA-NCAM and synaptophysin, a molecule often used as a marker of synaptogenesis, were substantially down-regulated by PCP. These effects were prevented by M40403, a superoxide dismutase mimetic that also prevented the PCP-induced terminal dUTP nick-end labeling of DNA fragments that was observed selectively in the cortex. These data suggest that PCP causes cell death by apoptosis selectively in the cortex, but not in the striatum, following either in vivo treatment of perinatal rat pups or in vitro treatment of corticostriatal slices. Further, cortical apoptosis induced by PCP negatively impacts striatal synaptogenesis, a process important in normal neural development. This deficit is probably caused by a reduction in corticostriatal neurotransmission. It is possible that the dysregulation of striatal synaptogenesis contributes to the behavioral abnormalities observed following perinatal PCP administration in vivo.

Analysis of Variance↗
PubMed2004

Caloric restriction and body weight independently affect longevity in Wistar rats.

OBJECTIVE: To evaluate the independent effects of caloric restriction (CR) and body weight (BW) on mortality rate (MR) and the extent to which BW may mediate the effect of CR on MR. DESIGN AND SUBJECTS: Data were from the Biosure Study, a randomized, controlled, prospective intervention study of diet regimens in 1200 Wistar rats. Animals were followed until they died spontaneously, were euthanized because of illness, or reached age 30 months. STATISTICAL ANALYSIS: Cox regression was performed to evaluate the effects of CR and BW on MR. Bootstrap procedures were used to test the contribution of BW to the effect of CR on MR. RESULTS: CR initiated after age 13 weeks decreased the rate of subsequent mortality. The MR increased with higher BW in early adulthood (21 weeks) and this effect persisted even after adjustment for CR. After adjustment for BW in early adulthood, we did not find a similar relation between mortality and BW in late adulthood (105 weeks). Mediation analysis indicated that low BW associated with CR appeared to mediate some of the mortality-reducing effects of CR, but CR clearly had effects independent of BW. The reductions in BW appeared to account for approximately 11% of the effect of CR. CONCLUSION: CR and BW have independent effects on MR in Wistar rats. BW may mediate a small part of the CR effects on MR.

Aging↗
PubMed2004

Molecular monitoring and evaluation of the application of the insect-pathogenic fungus Beauveria bassiana in southeast China.

AIMS: To monitor the fate of inundatively applied strains of Beauveria bassiana against Masson's pine caterpillar, Dendrolimus punctatus, in Magushan Forest, southeast China, and evaluate the potential environmental risks of biocontrol introduction. METHODS AND RESULTS: Filed samplings of mycosed cadavers were carried out continuously for more than one year after the inundative applications of two exotic B. bassiana strains. By employing four complementary molecular markers, the purified cultures from collections were characterized and the two released strains Bb17 and Bb13 were recovered with respective frequencies of 9.1 and 5.2%. The released strains were isolated from nontarget hosts. The genetic diversity of the population of B. bassiana in the trial plot changed dynamically over time and no single genotype strain dominated throughout the sampling period or at different seasons. The indigenous strains were observed to be predominant in the local environment. Co-infection and/or genetic recombination might occur between strains under natural conditions. CONCLUSION: Field applications of the biocontrol agent B. bassiana appear to pose no major risk to the environment. There was no evidence of displacement of indigenous strains of B. bassiana. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicate that the introduction of exotic B. bassiana strains can persist in local environment and infect nontarget insect hosts, highlighting the importance of safety assessment of the large-scale application of fungal biocontrol agents.

Animals↗
PubMed2004

Ki-ras gene mutations, LOH of the APC and DCC genes, and microsatellite instability in primary colorectal carcinoma are not associated with micrometastases in pericolonic lymph nodes or with patients' survival.

AIMS: The primary aim of this study was to look for possible correlations between molecular genetic changes in primary colorectal cancer and the presence or absence of micrometastases in the accompanying pericolonic lymph nodes. The secondary aim was to correlate the data on these molecular genetic changes and micrometastases with survival. METHODS: One hundred and twenty five Dukes's stage B colorectal cancers from 1989 to 1992 were analysed. The primary tumours were evaluated for Ki-ras mutation, adenomatous polyposis coli (APC) loss of heterozygosity (LOH), deleted in colon cancer (DCC) LOH, and microsatellite instability using standard molecular techniques. All available lymph nodes were immunohistochemically stained for micrometastases. RESULTS: Micrometastases were present in 41% of patients. There were significantly more lymph nodes removed in the patients with micrometastases. Micrometastases were not associated with Ki-ras mutation, APC LOH, DCC LOH, or microsatellite instability, even when controlling for the number of lymph nodes removed. None of the molecular variables considered had a significant impact on either overall survival or on death with disease. CONCLUSIONS: There are insufficient data to justify using molecular genetic changes in primary colorectal carcinomas as prognostic markers. Micrometastases do not provide prognostic information on survival. There is value in increasing the numbers of lymph nodes removed and analysed along with the primary tumour.

Aged↗
PubMed2004

Effect of high-level natural radiation on chromosomes of residents in southern China.

To study the effect of low-dose (rate) radiation on human health, we analyzed chromosomes of peripheral lymphocytes of residents in a high background radiation area (HBRA) and compared the results with those obtained from residents in a control area (CA) in Guangdong Province, China. Unstable types of chromosome aberrations (dicentrics and rings) were studied in 22 members of eight families in HBRA and 17 members of five families in CA. Each family consists of three generations. On average 2,600 cells per subject were analyzed. 27 adults and six children in HBRA and 25 adults and eight children in CA were studied with respect to translocations. On average 4,741 cells per subject were examined. We found an increase of the frequency of dicentrics and rings in HBRA, where the natural radiation level is three to five times higher than in the control area. But the increase of translocations in HBRA was within the range of individual variation in the controls.

Adult↗
PubMed2004

Short-term pharmacokinetic comparison of a novel testosterone buccal system and a testosterone gel in testosterone deficient men.

OBJECTIVE: The primary objective of the study was to compare the percentage of men with mean serum total T (C(ave(0-24))) within normal range during the 24-h pharmacokinetic (PK) sampling period on Days 14 and 15. METHODS: Treatment with a new testosterone (T) buccal system, (Striant), 30 mg twice daily was compared to a transdermal gel delivery system, (T-gel) [AndroGel 5 g containing 1% (50 mg) T] daily for 14 days in T-deficient men. Safety parameters included laboratory assessments and collection of adverse events. Patients were otherwise healthy T-deficient men with total T <or= 8.7 nmol/L (<or= 2.5 ng/mL). RESULTS: Twenty-six of the 28 patients enrolled (0.93 +/- 0.38 ng/mL) for T-gel, which was greater completed the 24-h PK assessment. Of the evaluable patients, 92.3% of T buccal system and 83.3% of T-gel patients had C(ave(0-24)) within the normal range of 10.4-36.4 nmol/L (3.0-10.5 ng/mL). Mean total T values were not different in the T buccal system group (C(ave(0-24)) 16.7 +/- 4.7 nmol/L; 4.8 +/- 1.4 ng/mL) compared to the T-gel group (C(ave(0-24)) 15.9 +/- 4.8 nmol/L; 4.6 +/- 1.4 ng/mL). All T values returned to baseline levels after the study drug was stopped. Serum LH and FSH levels decreased, and E(2) increased as expected following T administration. Differences in DHT concentrations between treatment groups were significant (p = 0.012) with mean DHT levels on Day 14 of 1.9 +/- 1.4 nmol/L (0.55 +/- 0.42 ng/mL) for the T buccal system and 3.2 +/- 1.3 nmol/L than the upper level of normal (2.9 nmol/L; 0.85 ng/mL). Statistically significant differences were seen in the mean T/DHT ratio on Days 14 and 15 with the T buccal system (9.3) and T-gel (5.0) (normal 9-12) (Day 14, p < 0.00001; Day 15, p < 0.0001). All adverse events were mild to moderate in severity. Three of 12 adverse events significant adverse effects in T-deficient men. The T were considered related to the study drug and included headache (1 for each of the T buccal system and T-gel), and breast pain (T-gel). SUMMARY AND CONCLUSIONS: In this short-term study, the T buccal system produced steady-state T levels comparable to those with T-Gel without buccal system provides an additional safe, effective and convenient option for testosterone replacement therapy in hypogonadal men.

Administration, Buccal↗
PubMed2004

Nutritional modulation of the cell cycle and breast cancer.

In the USA, breast cancer accounts for approximately 30% of all cancers diagnosed in women and is the second leading cause of cancer death in women. An understanding of the molecular genetic events governing breast cancer lead to both prevention and intervention strategies in an attempt to reduce mortality and morbidity from breast cancer. The last three decades of medical research examining the molecular pathogenesis of cancers have provided compelling evidence for the universal disruption of the cell cycle in human tumors. The importance of cell cycle control in human cancer was recognized by the recent award of the Nobel Prize to Drs Nurse and Hartwell for their discovery of the cyclins. More recent studies have demonstrated a critical interface between hormonal signaling and the cell cycle. In parallel, epidemiological studies have identified as being associated with breast cancer important dietary and environmental components that regulate hormonal signaling. This review describes the intersection of these two fields of study, which together imply a role for dietary prevention and intervention in human breast cancer perhaps through altering cell cycle components.

Androgens↗
PubMed2004

Model building and quantitative analysis of a tandem immuno-capturing assay as a screening tool for breast cancer.

The onset of breast cancer appears to occur, on average, a decade earlier in Mexican women in comparison to American or European women. Early detection and prevention of breast cancer are of crucial importance to increase survival and improve quality of life. Based on the molecular elucidation of critical events leading to breast carcinogenesis, a tandem immuno-capturing blood test was developed as a quantitative population screening assay in view of providing a cost-effective and non-invasive alternative to population screening. Clinical analysis of 63 Mexican women within an age group of 35-70, revealed that Interstron activity increases from 800+/-65 IUJPA (Interstron Units) in the asymptomatic normal women to 994+/-100 IUJPA in the symptomatic/benign group, reaching 1289+/-81 IUJPA in the cancerous group. Accordingly, activity thresholds were established at 800 and 1200 IUJPA respectively, encompassing three risk groups: (i) Healthy Otherwise Normal (<800 IUJPA); (ii) Grey Risk Area (>800 and <1200 IUJPA), and (iii) At Risk group (>1200 IUJPA). Taking into account both baseline and clinical case reports, the Healthy Otherwise Normal group and the At Risk group were mostly homogeneous in nature, comprising a population of normal and cancer patients respectively. The Grey Risk group is heterogeneous, likely reflecting a transitional nature towards a potential early stage of breast disease development. Based on these results, a screening algorithm was developed as the underlining principle for population surveillance encompassing over 30,000 Mexican women. The current screening results have enabled us to objectively prioritize medical attention to approximately 1 in 8 women out of the general population mapped within the At Risk group. Overall, our findings suggest that monitoring Interstron activity units provides a valuable quantitative screening analysis as to selectively streamline the population of women in need of early medical counseling and/or mammography, thereby enhancing both the quality and cost-effectiveness of preventative population surveillance programs targeting breast cancer.

Adult↗
PubMed2004

Milk trait heritability and correlation with heterozygosity in yak.

382 yak cows were examined for milk yield, fat, protein and lactose contents. Six polymorphic loci, alphas1-CN, kappa-CN, beta-CN, beta-Lg, alpha-La and MUC-1, were scored by PAGE electrophoresis for each individual. The values of milk yield, fat, protein and lactose content were 247.13 kg, 5.81%, 5.18% and 4.93%, respectively. Based on the 6 polymorphism loci, the average heterozygosity of the yak population was 0.1794. Calculated by the marker-based method, heritability estimates for milk yield, fat, protein and lactose contents were 0.353 +/- 0.093, 0.316 +/- 0.101, 0.415 +/- 0.098 and 0.481 +/- 0.035, respectively. The relatively high or medium heritability of these traits indicate that it is feasible to rely directly on them in breeding for the improvement in a relatively short period. The significant linear regression between heterozygosity and fat percentage with a positive slope (R = 0.0420) indicated that inbreeding affected milk fat content in this population.

Animals↗