Biomedical subjects

Ping Sun

Publications and source records attributed to Ping Sun.

At least 37 records · Page 2Linked to original sources

PubMed2006

Development of dinitrophenylated cyclodextrin derivatives for enhanced enantiomeric separations by high-performance liquid chromatography.

The synthesis and evaluation of new dinitrophenyl (DNP) substituted beta-cyclodextrin (beta-CD) chiral stationary phases (CSPs) for the enantioseparation of various classes of chiral analytes by HPLC are presented. The dinitrophenyl substituted beta-CD derivatives are synthesized and covalently bonded to functionalized 5 microm spherical porous silica gel. These are the first reported derivatized cyclodextrin which contains pi-electron deficient substituents (i.e., pi-acidic moieties). The column performance in terms of their ability to separate enantiomers is evaluated. A variety of different dinitro-substituted aryl groups are investigated and compared. The pH of the mobile phase buffers, the buffer composition, the number and position of the dinitro groups on the phenyl ring substituent, the degree of substitution, and the bonding strategy all greatly affect the performance of the CSPs. A large variety of racemic compounds have been separated successfully on these CSPs. The bonded dinitrophenyl-derivatized cyclodextrins are stable in all three mobile phase modes, namely, the reversed-phase, polar organic, and normal phase modes. No degradation in column performance was observed in any mode of operation even after more than 1000 injections. The analytical applicability of these types of CSPs for enantiomeric separations is discussed in detail.

Alcohols↗

PubMed2006

[A three-year clinical evaluation of galvano-ceramic bridges made by Ni-Cr pontic bonding galvano caps].

OBJECTIVE: To evaluate the clinical effect of galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps with highly temperature-resistant adhesive based on three-year clinical trials. METHODS: A total of 29 galvano-ceramic bridges made by Ni-Cr pontic fired bonding on the galvano caps were used for 26 patients. Abutment teeth plaque indices (PI) were compared according to Silness and Löe standards and their papillary bleeding indices (PBI) according to Mazza standards before restoration and after 36 months' restoration. At the same time, the integrity and marginal fitness of galvano-ceramic bridges were observed. RESULTS: The PBI at abutment teeth were higher than those before restoration, Wilcoxon test revealed significant difference. Their PI were lower than those before restoration, Wilcoxon test revealed significant difference. All the galvano-ceramic bridges were perfect in marginal fitness and color. The rate of integrity was 89.7% in the period of observation. CONCLUSION: Galvano-ceramic bridges made by Ni-Cr pontic fired bonding galvano caps with highly temperature-resistant adhesive hold out good prospects for clinical use in fixed restoration.

Adult↗

PubMed2006

Temporal and spatial trends of organochlorine pesticides in Great Lakes precipitation.

Organochlorine pesticide concentrations in precipitation samples collected from 1997 to 2003 at seven Integrated Atmospheric Deposition Network sites around the Great Lakes are reported. The 28-day volume weighted mean concentrations of several pesticides, including gamma-hexachlorocyclohexane (HCH), endosulfan, hexachlorobenzene, chlordane, and DDE, showed significant seasonal trends. For current-use pesticides (endosulfan and gamma-HCH), their concentrations peaked in late spring to summer just after their agricultural application. For the banned pesticides, higher concentrations were observed in the winter due to their enhanced partitioning to particles and scavenging by snow. Long-term decreasing trends were observed for several pesticides such as gamma-HCH and DDE. On the other hand, beta-HCH showed significant increasing concentrations as a function of time at Brule River, Eagle Harbor, and Sleeping Bear Dunes. Generally, Chicago had the highest concentration of chlordanes, dieldrin, and DDT, indicating that urban areas could be a source for these compounds to precipitation. For gamma-HCH and endosulfans, Point Petre had the highest concentrations due to the application of these pesticides in the surrounding areas.

Fresh Water↗

PubMed2006

Spontaneous and therapeutic abortions and the risk of breast cancer among BRCA mutation carriers.

INTRODUCTION: BRCA1 and BRCA2 mutation carriers are at increased risk for developing both breast and ovarian cancer. It has been suggested that carriers of BRCA1/2 mutations may also be at increased risk of having recurrent (three or more) miscarriages. Several reproductive factors have been shown to influence the risk of breast cancer in mutation carriers, but the effects of spontaneous and therapeutic abortions on the risk of hereditary breast cancer risk have not been well studied to date. METHODS: In a matched case-control study, the frequencies of spontaneous abortions were compared among 1,878 BRCA1 mutation carriers, 950 BRCA2 mutation carriers and 657 related non-carrier controls. The rates of spontaneous and therapeutic abortions were compared for carriers with and without breast cancer. RESULTS: There was no difference in the rate of spontaneous abortions between carriers of BRCA1 or BRCA2 mutations and non-carriers. The number of spontaneous abortions was not associated with breast cancer risk among BRCA1 or BRCA2 mutation carriers. However, BRCA2 carriers who had two or more therapeutic abortions faced a 64% decrease in the risk of breast cancer (odds ratio = 0.36; 95% confidence interval 0.16-0.83; p = 0.02). CONCLUSION: Carrying a BRCA1 or BRCA2 mutation is not a risk factor for spontaneous abortions and spontaneous abortions do not appear to influence the risk of breast cancer in carriers of BRCA1 or BRCA2 mutations. However, having two or more therapeutic abortions may be associated with a lowered risk of breast cancer among BRCA2 carriers.

Abortion, Spontaneous↗

PubMed2006

Ultrasound-targeted microbubble destruction improves the low density lipoprotein receptor gene expression in HepG2 cells.

Ultrasound-targeted microbubble destruction had been employed in gene delivery and promised great potential. Liver has unique features that make it attractive for gene therapy. However, it poses formidable obstacles to hepatocyte-specific gene delivery. This study was designed to test the efficiency of therapeutic gene transfer and expression mediated by ultrasound/microbubble strategy in HepG2 cell line. Air-filled albumin microbubbles were prepared and mixed with plasmid DNA encoding low density lipoprotein receptor (LDLR) and green fluorescent protein. The mixture of the DNA and microbubbles was administer to cultured HepG2 cells under variable ultrasound conditions. Transfection rate of the transferred gene and cell viability were assessed by FACS analysis, confocal laser scanning microscopy, Western blot analysis and Trypan blue staining. The result demonstrated that microbubbles with ultrasound irradiation can significantly elevate exogenous LDLR gene expression and the expressed LDLRs were functional and active to uptake their ligands. We conclude that ultrasound-targeted microbubble destruction has the potential to promote safe and efficient LDLR gene transfer into hepatocytes. With further refinement, it may represent an effective nonviral avenue of gene therapy for liver-involved genetic diseases.

Cell Line, Tumor↗

PubMed2006

A randomized intervention of smoking for adolescents in urban Wuhan, China.

BACKGROUND: Tobacco use is a significant public health problem in China. Culturally specific smoking prevention programs are needed for Chinese adolescents. This study evaluated a school-based smoking prevention curriculum with a social normative approach developed in the United States for adolescents in urban Wuhan, China. METHODS: As a randomized trial, the intervention was implemented in 1998 with 7th grade students in seven schools with seven matched control schools. Multilevel logistic regression models were used to compare ever and recent (past-month) smoking behaviors for the control and program conditions. RESULTS: At the 1-year follow-up, smoking had increased more rapidly in the control schools than in the program schools. The odds of baseline nonsmokers initiating smoking did not differ between the program and control groups (OR=1.08 with 95% CI=0.71, 1.64). The program prevented progression to recent smoking among boys who were baseline ever smokers. Among boys who were recent smokers at baseline, the prevention program significantly reduced risk of remaining recent smokers at follow-up (OR=0.45 with 95% CI=0.23, 0.88). CONCLUSIONS: This social normative smoking prevention curriculum did not demonstrate a significant primary prevention effect but showed potential for secondary prevention. Culturally specific smoking prevention programs are needed for Chinese adolescents.

Adolescent↗

PubMed2006

Temporal trends of polychlorinated biphenyls in precipitation and air at chicago.

Polychlorinated biphenyl (PCB) concentrations in precipitation (1997-2003) and in the atmospheric gas phase (1996-2003) collected in Chicago, IL, are reported. These data were obtained as part of the Integrated Atmospheric Deposition Network. For comparison, PCB concentrations at a remote site, Sleeping Bear Dunes on the northeastern shore of Lake Michigan, are also reported. Much higher PCB concentrations in both precipitation (7.1 +/- 0.9 ng/L) and the gas phase (1.4 +/- 0.1 ng/m3) at Chicago compared to Sleeping Bear Dunes (1.1 +/- 0.1 ng/L and 0.1 +/- 0.08 ng/m3, respectively) indicate that Chicago is a source of PCBs to the Great Lakes. A long-term decreasing trend of PCB concentrations in precipitation was observed at Chicago with a half-life of 6.8 +/- 3.1 years. The corresponding half-life for PCB concentrations in the gas phase was 7.7 +/- 1.1 years. The significant long-term decrease of PCB concentrations in precipitation and the gas phase in Chicago suggests that regulatory efforts are working, at least in this city.

Air Pollutants↗

PubMed2006

Liquid chromatographic method for the simultaneous determination of cefalexin and trimethoprim in dog plasma and application to the pharmacokinetic studies of a coformulated preparation.

A liquid chromatographic method is described for the simultaneous determination of cefalexin and trimethoprim in dog plasma. A simple protein precipitation procedure was adopted for the sample preparation with satisfactory extraction recoveries for both analytes. Chromatographic separation of the analytes was achieved on a C(18) column using a mixture of 2 mol/l formate buffer (pH 3.5), methanol and acetonitrile (22:7:7, v/v/v) containing a 0.002 mol/l sodium dodecyl sulfate as mobile phase and detection was performed at 240 nm. The linearity was obtained over the concentration ranges of 1.0-100.0 microg/ml for cefalexin and 0.5-50.0 microg/ml for trimethoprim. For each level of QC samples including the lower limit of quantification, both inter- and intra-day precisions (R.S.D.) were < or =14.0% for cefalexin and < or =11.4% for trimethoprim, and accuracy (RE) was -1.4% for cefalexin and -3.0% for trimethoprim. The present LC method was successfully applied to the pharmacokinetic studies of coformulated cefalexin dispersible tablets after oral administration to beagle dogs.

Animals↗

PubMed2006

Weight perception and weight-related sociocultural and behavioral factors in Chinese adolescents.

BACKGROUND: Rapid economic development accompanied by imported Western media, advertising, fashion, and lifestyle in mainland China has resulted in shifts in cultural beliefs and beauty ideals in adolescents. The present study focused on understanding relationships among weight perception and weight-related sociocultural and behavioral factors in Chinese adolescents. METHODS: Data collected in 2002 from 6863 middle and high school students and their parents from four large cities in mainland China were used. Weight status was determined by measured weight and height. Weight perception, media exposure, attitudes, and health behaviors were assessed by a structured questionnaire survey. RESULTS: Boys were more likely to describe themselves as either too thin or relatively thin than girls (37.32% vs. 18.79%), while girls more often considered themselves either relatively heavy or too heavy than boys (50.83% vs. 26.54%). Girls who were actually normal or underweight were more likely than boys to describe themselves as either relatively heavy or very heavy (41.6% vs. 11.6%), while boys who were actually normal or overweight were more likely than girls to believe themselves as underweight (30.9% vs. 15.7%). Girls who were frequently exposed to media from Japan, Korea, Hong Kong, and Taiwan, and placed high value on their physical appearance, were more likely to be dissatisfied with their body weight, which in turn were more likely to restrict consumption of certain foods, smoke cigarettes, and drink alcohol. Similar results were not observed in boys. CONCLUSIONS: Weight dissatisfaction was prevalent in Chinese adolescents and was significantly related to media exposure, attitudes towards physical appearance, and adoption of certain health-risk behaviors in girls. Our findings underscore the importance of sociocultural influences in shaping realistic body image and have implications for prevention and early intervention for establishing health behavioral practices during adolescence.

Adolescent↗

PubMed2006

Annual variation of polycyclic aromatic hydrocarbon concentrations in precipitation collected near the Great Lakes.

Polycyclic aromatic hydrocarbon (PAH) concentrations were measured in precipitation samples collected from 1997 to 2003 at seven sites near the Great Lakes as a part of the Integrated Atmospheric Deposition Network. The 28-day integrated concentrations of most PAHs showed significant seasonal trends with higher concentrations in the winter and lower concentrations in the summer. Long-term decreasing trends were observed for all PAHs measured in precipitation at Chicago. At the sites on Lakes Superior, Michigan,,and Erie, most PAHs did not show significant long-term trends. At the two Canadian sites on Lakes Huron and Ontario, lower molecular weight PAHs (e.g., fluorene to pyrene) showed long-term decreasing trends; however, no long-term trends were observed for higher molecular weight PAHs at these sites. Interestingly, retene, a marker for wood burning, showed increasing trends at the sites on Lakes Superior and Michigan. For all the other PAHs, precipitation collected at Chicago had by far the highest PAH concentrations followed by the site on Lake Erie. Generally, the Lake Superior sites had the lowest PAH concentrations. However, retene concentrations in precipitation collected at the Lake Superior site were higher compared to Lakes Michigan and Erie, which indicate more residential wood burning in the far north of the Great Lakes basin.

Air Pollutants↗

PubMed2006

Project Towards No Drug Abuse: long-term substance use outcomes evaluation.

OBJECTIVES: This paper presents up to 5 years post-program outcomes of Project Towards No Drug Abuse (Project TND), a drug abuse prevention program conducted in South California alternative high school system during years 1994-1999. METHODS: The effects of a 9-session health motivation--social skills--decision-making curriculum were evaluated. Twenty-one schools recruited were randomly assigned to standard care (control), classroom only, or a classroom plus semester-long school-as-community component. Last 30-day use of cigarettes, alcohol, marijuana, and hard drugs were assessed at three time intervals: short-term (year 1), middle-term (years 2 or 3), and long-term (years 4 or 5). Multilevel random coefficients modeling were employed to estimate the adjusted levels of substance use. RESULTS: Among 1578 baseline subjects, follow-up data were available for 68% (year 1), 66% (years 2 or 3), and 46% (years 4 or 5) of subjects, respectively. Results revealed significant positive long-term program effects for hard drug use at year 4 or 5 for the two program interventions (P = 0.02). CONCLUSIONS: Project TND reduced hard drug use in the 46% who were successfully followed. It is the first program to demonstrate long-term self-reported behavioral effects on hard drug use among high-risk youth by using a school-based, limited-session model.

Adolescent↗

PubMed2006

Coffee consumption and breast cancer risk among BRCA1 and BRCA2 mutation carriers.

Although there are several plausible biologic mechanisms whereby coffee consumption might influence the risk of breast cancer, epidemiologic evidence is limited. We assessed the association between coffee consumption and breast cancer risk among high-risk women who carry BRCA mutations. We performed a matched case-control analysis on 1,690 women with a BRCA1 or BRCA2 mutation from 40 centers in 4 countries. Average lifetime coffee consumption was estimated via a self-administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. After adjustment for potential confounders, the ORs for breast cancer in BRCA carriers who habitually drank 0, 1-3, 4-5 and 6 or more cups of coffee were 1.00, 0.90 (95% CI 0.72-1.12), 0.75 (95% CI 0.47-1.19) and 0.31 (95% CI 0.13-0.71; p-trend = 0.02). The effect was limited to the consumption of caffeinated coffee. These results suggest that among women with BRCA gene mutation, coffee consumption is unlikely to be harmful and that high levels of consumption may in fact be related to reduced breast cancer risk.

Adult↗

PubMed2006

Influence of selected lifestyle factors on breast and ovarian cancer risk in BRCA1 mutation carriers from Poland.

It has been estimated that the lifetime risk of breast cancer among women who inherit a BRCA1 or BRCA2 mutation is as high as 80%, and the risk estimates for ovarian cancer range from 15 to 40%. Several environmental and lifestyle factors are believed to contribute to the development of breast cancer in the general population and it is of interest to establish if these factors operate among mutation carriers as well. To evaluate the effects of age of menarche, parity, breast-feeding, oophorectomy and oral contraceptive use, as well as smoking and coffee consumption, on the risks of breast and ovarian cancer, we conducted a matched case-control study of Polish women with BRCA1 mutations. There were 348 breast cancer patients, 150 ovarian cancer patients and similar numbers of age-matched controls. BRCA1 carriers with late age of menarche, lower parity and long-term breast-feeding were less likely to develop breast cancer. Oral contraceptives protected against ovarian cancer.

Adolescent↗

PubMed2006

Method of cooking and risk of breast cancer in the Philippines.

OBJECTIVE: Among Asian countries, the highest age-standardized rates of breast cancer have been reported for the Philippines. The influence of diet and lifestyle factors as possible contributors to these high rates has not been well-studied. We conducted a case-control study in Manila to examine the association between methods of cooking and the risk of breast cancer. METHODS: Eligible subjects were women undergoing evaluation at the Philippine General Hospital (PGH), Manila for a breast problem. All of the women completed a risk factor questionnaire prior to the determination of their case (n = 240) or control (n = 240) status. Information regarding current, as well as usual method of cooking in the household at 12 years of age was obtained. RESULTS: Boiling food in coconut milk was associated with a significantly increased risk of breast cancer (odds ratio (OR) = 2.2; 95% confidence interval (CI) 1.3-3.8). There were positive associations between boiling food in coconut milk and the risk of breast cancer currently (OR = 1.9; 95% CI 1.0-3.3), and at 12 years of age (OR = 2.9; 95% CI 1.6-5.5). A positive association between frying food and breast cancer risk was restricted to women whose household fried food at 12 years of age (OR = 1.89; 95% CI 1.1-3.4). CONCLUSIONS: The results of this study suggest that various cooking methods during adolescence and possibly in adulthood may be associated with an increased risk of breast cancer. These findings require confirmation.

Adult↗

PubMed2006

Screening mammography and risk of breast cancer in BRCA1 and BRCA2 mutation carriers: a case-control study.

BACKGROUND: Screening mammography is associated with a small dose of radiation to the breast, and women with increased genetic risk might be particularly sensitive to the DNA-damaging effects of ionising radiation. We aimed to assess whether exposure to ionising radiation through mammography screening was associated with risk of breast cancer in BRCA1 or BRCA2 mutation carriers. METHODS: We identified 1600 cases of breast cancer and 1600 controls without breast cancer who were matched for BRCA mutation, date of birth (within 1 year), and country of residence from an international registry of BRCA1 and BRCA2 mutation carriers. We used a questionnaire to inquire about whether participants had ever had screening mammography, and, if so, the age at which they first had the procedure. RESULTS: We found no association between ever having screening mammography and risk of breast cancer (odds ratio [OR] 1.03 [95% CI 0.85-1.25], adjusted for parity, oral-contraceptive use, ethnic origin, and bilateral oophorectomy). The association was much the same for BRCA1 mutation carriers and BRCA2 mutation carriers (1.04 [0.84-1.29] vs 1.06 [0.67-1.66], respectively, adjusted for parity, oral-contraceptive use, ethnic origin, and bilateral oophorectomy). INTERPRETATION: These findings do not lend support to the idea that exposure to ionising radiation through routine screening mammography contributes substantially to the burden of breast cancer in BRCA1 and BRCA2 mutation carriers. Prospective studies are needed to confirm the results of this initial report, and, where possible, these studies should assess a more appropriate endpoint of total exposure.

Adult↗

PubMed2006

A meta-analysis of teen cigarette smoking cessation.

OBJECTIVE: This article presents a meta-analysis of 48 teen cigarette smoking cessation studies, the 1st meta-analysis of its kind. The authors conducted searches of electronic databases and unpublished manuscripts from 1970 to 2003. Fifty contextual elements were coded from each article. A weighted least squares random effects method was used to pool results from individual study net effects estimates. Multilevel random coefficients modeling was applied to control for the intrastudy variation. MAIN OUTCOME MEASURES: The primary outcome for the present analysis was quit rate. Data were entered as intent-to-treat (ITT) quit rates (not compliance sample rates). Overall treatment effect size and treatment effect sizes as a function of program content, modality, number of sessions, and length of follow-up were examined. RESULTS: Across studies, program conditions, compared with control conditions, appeared to give smokers a 2.90% (95% confidence interval = 1.47-4.35%) absolute advantage in quitting, increasing the probability of quitting by approximately 46% (9.14% vs. 6.24%). Relatively higher quit rates were found in programs that included a motivation enhancement component, cognitive-behavioral techniques, and social influence approaches. Also, relatively higher quit rates were found in school-based clinic and classroom modalities. Furthermore, relatively higher quit rates were found for programs consisting of at least 5 quit sessions. Data also indicated that the effects were maintained at short-term (1 year or less) and longer term (longer than 1 year) follow-ups. CONCLUSION: Much more teen smoking cessation research is needed, but teen smoking cessation programming is effective, and the present study provides a framework to move forward.

Adolescent↗

PubMed2006

Influences affecting adolescent smoking behavior in China.

This study examined multiple influences on the use of tobacco by adolescents in China. Using the theory of triadic influences as a guide, we selected interpersonal, attitudinal/cultural, and intrapersonal constructs from baseline data to predict adolescent smoking 1 year later. We used prospective data from middle and high school students (N = 11,583) and their parents from the China Seven Cities Study, a longitudinal study that is evaluating the effects of changing economic and social factors on health behaviors including tobacco use. A multilevel regression analysis provided some support that each of the influences in the theory of triadic influences affects adolescent smoking in China. After adjusting for important confounders including age, gender, socioeconomic status, and smoking behaviors (lifetime and past 30-day) at baseline, we found significant risk factors within each of the three categories, including interpersonal influences (parental monitoring, good friend smoking, and peer smoking), attitudinal/cultural influences (school academic ranking, initial liking of smoking, and the meaning of smoking), and intrapersonal influences (susceptibility to smoking, and low self-confidence to quit smoking). Results suggest that the etiology of smoking among adolescents in China might be similar to that observed in western countries and that some of the techniques used successfully in prevention programs in those countries might be useful guides when developing prevention programs in China.

Adolescent↗

PubMed2006

Transcriptional regulation of PEN-2, a key component of the gamma-secretase complex, by CREB.

Gamma-secretase, which is responsible for the intramembranous cleavage of Alzheimer's beta-amyloid precursor protein (APP), the signaling receptor Notch, and many other substrates, is a multiprotein complex consisting of at least four components: presenilin (PS), nicastrin, APH-1, and PEN-2. Despite the fact that PEN-2 is known to mediate endoproteolytic cleavage of full-length PS and APH-1 and nicastrin are required for maintaining the stability of the complex, the detailed physiological function of each component remain elusive. Unlike that of PS, the transcriptional regulation of PEN-2, APH-1, and nicastrin has not been investigated. Here, we characterized the upstream regions of the human PEN-2 gene and identified a 238-bp fragment located 353 bp upstream of the translational start codon as the key region necessary for the promoter activity. Further analysis revealed a CREB binding site located in the 238-bp region that is essential for the transcriptional activity of the PEN-2 promoter. Mutation of the CREB site abolished the transcriptional activity of the PEN-2 promoter. Electrophoretic mobility shift assays and chromatin immunoprecipitation analysis showed the binding of CREB to the PEN-2 promoter region both in vitro and in vivo. Activation of the CREB transcriptional factor by forskolin dramatically promoted the expression of PEN-2 mRNA and protein, whereas the other components of the gamma-secretase complex remained unaffected. Forskolin treatment slightly increases the secretion of soluble APPalpha and Abeta without affecting Notch cleavage. These results demonstrate that expression of PEN-2 is regulated by CREB and suggest that the specific control of PEN-2 expression may imply additional physiological functions uniquely assigned to PEN-2.

Amyloid Precursor Protein Secretases↗