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1.  Diversity of endophytic bacteria in Malaysian plants as revealed by 16S rRNA encoding gene sequence based method of bacterial identification☆ 
Bacterial endophytes do have several potential applications in pharmacy, medicine and agricultural biotech industry. The main objective of this study was to understand types of bacterial endophytes associated with dicotyledonous (dicot) and monocotyledonous (monocot) plant species. Isolation of the endophytic bacteria was performed using surface-sterilized various tissue samples, and identification of the endophytic bacterial isolates (EBIs) was completed using 16S rRNA encoding gene sequence similarity based method. In total, 996 EBIs were isolated and identified from 1055 samples of 31 monocot and 65 dicot plant species from Peninsular Malaysia. The 996 EBIs represented 71 different types of bacterial species. Twelve (12) out of 71 species are reported as endophytes for the first time. We conclude that diverse types of bacterial endophytes are associated with dicot and monocot plants, and could be useful in pharmacy, medicine and agricultural biotechnology for various potential applications.
PMCID: PMC3812885  PMID: 24396249
Dicots; Endophytes; Monocots; Natural compounds; Bioprospecting
2.  Health Beliefs Associated with Cervical Cancer Screening Among Vietnamese Americans 
Journal of Women's Health  2013;22(3):276-288.
Vietnamese American women represent one of the ethnic subgroups at great risk for cervical cancer in the United States. The underutilization of cervical cancer screening and the vulnerability of Vietnamese American women to cervical cancer may be compounded by their health beliefs.
The objective of this study was to explore the associations between factors of the Health Belief Model (HBM) and cervical cancer screening among Vietnamese American women.
Vietnamese American women (n=1,450) were enrolled into the randomized controlled trial (RCT) study who were recruited from 30 Vietnamese community-based organizations located in Pennsylvania and New Jersey. Participants completed baseline assessments of demographic and acculturation variables, health care access factors, and constructs of the HBM, as well as health behaviors in either English or Vietnamese.
The rate of those who had ever undergone cervical cancer screening was 53% (769/1450) among the participants. After adjusting for sociodemographic variables, the significant associated factors from HBM included: believing themselves at risk and more likely than average women to get cervical cancer; believing that cervical cancer changes life; believing a Pap test is important for staying healthy, not understanding what is done during a Pap test, being scared to know having cervical cancer; taking a Pap test is embarrassing; not being available by doctors at convenient times; having too much time for a test; believing no need for a Pap test when feeling well; and being confident in getting a test.
Understanding how health beliefs may be associated with cervical cancer screening among underserved Vietnamese American women is essential for identifying the subgroup of women who are most at risk for cervical cancer and would benefit from intervention programs to increase screening rates.
PMCID: PMC3601630  PMID: 23428284
3.  Social influences on Cigarette Smoking Among Mainland Chinese and Chinese Americans: A Comparative Study 
The purpose of this cross-national study was to determine the leading social influences on smoking among Chinese Americans and mainland Chinese adults with the aim of improving prevention and intervention strategies to reduce smoking rates. A comparative cross-sectional design was used and a stratified-cluster sampling technique was employed in identifying the study sample. An 80-item questionnaire was administered in Chinese to 1222 participants, 812 in China and 410 in the U.S. Data were analyzed using descriptive and inferential statistical tests. Results contain comparative data on social influences of smoking among Chinese Americans and mainland Chinese, as well as factors influencing smoking behavior which include cultural beliefs, gender roles, and family relationship dynamics. Grandparents were influential and significantly correlated with current smokers in China. Findings indicate differential effects of social influences on smoking behavior. Similarities and differences provide a basis for improving and/or developing smoking intervention programs of mutual benefit to China and the U.S..
PMCID: PMC3914219  PMID: 24511220
4.  Validated method to measure yakuchinone A in plasma by LC-MS/MS and its application to a pharmacokinetic study in rats 
Yakuchinone A has a plethora of beneficial biological effects. However, the pharmacokinetic (PK) data of yakuchinone A still remain unknown so far. Furthermore, the quantification of yakuchinone A in biological samples has not been reported in the literature. Therefore, in the present study we aimed to develop a new method for the fast, efficient and accurate assessment of yakuchinone A concentration in plasma, as a means for facilitating the PK evaluation of yakuchinone A.
A liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of yakuchinone A in rat plasma. Mass spectrometric and chromatographic conditions were optimized. Plasma samples were pretreated by protein precipitation with methanol. LC separation was performed on a Phenomenex Luna C18 column with gradient elution using a mobile phase consisting of methanol–water containing 0.5 mM formic acid (HCOOH) at a flow rate of 0.28 mL/min. ESI-MS spectra were acquired in positive ion multiple reaction monitoring mode (MRM). The precursor-to-product ion pairs used for MRM of yakuchinone A and yakuchinone B were m/z 313.1 → 137.0 and 311.2 → 117.1, respectively. Low concentration of HCOOH reduced the ion suppression caused by matrix components and clearly improved the analytical sensitivity. Yakuchinone A showed good linearity over a wide concentration range (r > 0.99). The accuracy, precision, stability and linearity were found to be within the acceptable criteria. This new method was successfully applied to analyze the rat plasma concentration of parent yakuchinone A after a single oral administration of SuoQuan capsules. Low systemic exposure to parent yakuchinone A was observed.
The proposed method is sensitive and reliable. It is hoped that this new method will prove useful for the future PK studies.
PMCID: PMC3896807  PMID: 24422995
Yakuchinone A; LC-MS/MS; Matrix effects; HCOOH; Pharmacokinetic study; SuoQuan capsules
5.  Quantitative analysis of the major constituents in Chinese medicinal preparation SuoQuan formulae by ultra fast high performance liquid chromatography/quadrupole tandem mass spectrometry 
The SuoQuan formulae containing Fructus Alpiniae Oxyphyllae has been used to combat the urinary incontinence symptoms including frequency, urgency and nocturia for hundreds of years in China. However, the chemical information was not well characterized. The quality control marker constituent only focused on one single compound in the current Chinese Pharmacopeia. Hence it is prudent to identify and quantify the main constituents in this herbal product. This study aimed to analyze the main constituents using ultra-fast performance liquid chromatography coupled to tandem mass spectrometry (UFLC-MS/MS).
Fourteen phytochemicals originated from five chemical classes constituents were identified by comparing the molecular mass, fragmentation pattern and retention time with those of the reference standards. A newly developed UFLC-MS/MS was validated demonstrating that the new assay was valid, reproducible and reliable. This method was successfully applied to simultaneously quantify the fourteen phytochemicals. Notably, the content of these constituents showed significant differences in three pharmaceutical preparations. The major constituent originated from each of chemical class was isolinderalactone, norisoboldine, nootkatone, yakuchinone A and apigenin-4’,7-dimethylther, respectively. The variation among these compounds was more than 1000 times. Furthermore, the significant content variation between the two different Suoquan pills was also observed.
The proposed method is sensitive and reliable; hence it can be used to analyze a variety of SuoQuan formulae products produced by different pharmaceutical manufacturers.
PMCID: PMC3733971  PMID: 23899222
Fructus Alpiniae Oxyphyllae; Radix Linderae; SuoQuan formulae; UFLC-MS/MS; Alkaloids; Diarylheptanoids; Flavonoids; Lactones; Naphthalenone
6.  Pathways of cervical cancer screening among Chinese women 
The purpose of this community-based study was to develop a structural equation model for factors contributing to cervical cancer screening among Chinese American women.
A cross-sectional design included a sample of 573 Chinese American women aged 18 years and older. The initial step involved use of confirmatory factor analysis, that included the following variables: access to and satisfaction with health care, and enabling and predisposing cultural and health beliefs. Structural equation model analyses were conducted on factors related to cervical cancer screening.
Age, marital status, employment, household income, and having health insurance, but not educational level, were significantly related to cervical screening status. Predisposing and enabling factors were positively associated with cervical cancer screening. The cultural factor was significantly related to the enabling factor or the satisfaction with health care factor.
This model highlights the significance of sociocultural factors in relation to cervical cancer screening. These factors were significant, with cultural, predisposing, enabling, and health belief factors and access to and satisfaction with health care reinforcing the need to assist Chinese American women with poor English fluency in translation and awareness of the importance of cervical cancer screening. Community organizations may play a role in assisting Chinese American women, which could enhance cervical cancer screening rates.
PMCID: PMC3702238  PMID: 23843708
Papanicolaou test; cervical cancer screening; Chinese women
7.  Factors Associated with Colorectal Cancer Screening Among Cambodians, Vietnamese, Koreans and Chinese Living in the United States 
The purpose of this community-based participatory study was to identify factors associated with colorectal cancer (CRC) screening compliance and non-compliance among Cambodians, Vietnamese, Koreans and Chinese men and women 50 years and older living in the United States. A cross-sectional design was used in the study. The completed sample included 815 Asian Americans which included Cambodians (N=215), Vietnamese (N=195), Koreans (N=94) and Chinese (N=311). A 95-item questionnaire was developed and pilot tested for content validity and reliability. An in-person data collection approach was utilized and participants were given choice in responding in English or their native language. Of the 815 participants, 79.1% (N=645) reported never-screened, 7.9% (N=64), non-compliance, and 13.0% (N=106) compliance. Education was significantly associated with never-screened for CRC for Vietnamese and Chinese; employment status for Cambodians and Koreans; lack of health insurance for Cambodians, Korean and Chinese; English fluency and years lived in the U.S. for Vietnamese, Koreans, and Chinese. Less acculturated Asian Americans were more likely to be never screened, but differentially across ethnic subgroups. Barriers to screening included lack of knowledge, language, transportation, and time. Increased culturally-targeted public awareness and education programs are needed to improve CRC screening and compliance among high risk Asian American ethnic subgroups.
PMCID: PMC3521597  PMID: 23243486
sigmoidoscopy or colonoscopy; fecal occult blood test; Vietnamese; Korean; Chinese; Cambodian; correlates of colorectal cancer screening
8.  Correlates of Cervical Cancer Screening among Vietnamese American Women 
Objective. Vietnamese American women are at the greatest risk for cervical cancer but have the lowest cervical cancer screening rates. This study was to determine whether demographic and acculturation, healthcare access, and knowledge and beliefs are associated with a prior history of cervical cancer screening among Vietnamese women. Methods. Vietnamese women (n = 1450) from 30 Vietnamese community-based organizations located in Pennsylvania and New Jersey participated in the study and completed baseline assessments. Logistic regression analyses were performed. Results. Overall levels of knowledge about cervical cancer screening and human papillomavirus (HPV) are low. Factors in knowledge, attitude, and beliefs domains were significantly associated with Pap test behavior. In multivariate analyses, physician recommendation for screening and having health insurance were positively associated with prior screening. Conclusion. Understanding the factors that are associated with cervical cancer screening will inform the development of culturally appropriate intervention strategies that would potentially lead to increasing cervical cancer screening rates among Vietnamese women.
PMCID: PMC3449126  PMID: 23008526
9.  The Role of Sociocultural Factors in Hepatitis B Screening Among Asian Americans 
Southern Medical Journal  2011;104(7):466-472.
PMCID: PMC3298880  PMID: 21886043
Hepatitis B (HBV) screening; Asian Americans; sociocultural factors
10.  Prostate Cancer Screening Among Chinese American Men: A Structural Model 
To test the Sociocultural Health Behavior Model in relation to the health behavior of prostate cancer (PCa) screening among Chinese American men.
Confirmatory factor analysis and structural equation model analyses were conducted among Chinese American men.
The path analysis supported the components of the sociocultural model and indicated a positive and significant relationship between PCa screening and the enabling factors; between cultural factors and predisposing, enabling, and access/satisfaction with health care factors; and between enabling factors and access/satisfaction with health care.
The model highlights the significance that sociocultural factors play in relation to PCa screening.
PMCID: PMC3325499  PMID: 22488399
digital rectal exam; prostate specific antigen (PSA) blood test; prostate cancer screening; structural equation model
11.  Health seeking behavioral analysis associated with breast cancer screening among Asian American women 
The purpose of this community-based study was to apply a Sociocultural Health Behavior Model to determine the association of factors proposed in the model with breast cancer screening behaviors among Asian American women.
A cross-sectional design included a sample of 682 Chinese, Korean, and Vietnamese women aged 40 years and older. The frequency distribution analysis and Chi-square analysis were used for the initial screening of the following variables: sociodemographic, cultural, enabling, environmental, and social support. Univariate and multivariate analyses were conducted on factors for breast cancer screening using multinomial logistic regression analysis.
Correlates to positive breast cancer screening included demographics (ethnicity), cultural factors (living in the United States for 15 years or more, speaking English well), enabling factors (having a regular physician to visit, health insurance covering the screening), and family/social support factors (those who had a family/friend receiving a mammogram).
The results of this study suggest that breast cancer screening programs will be more effective if they include the cultural and health beliefs, enabling, and social support factors associated with breast cancer screening. The use of community organizations may play a role in helping to increase breast cancer screening rates among Asian American women.
PMCID: PMC3379860  PMID: 22723730
breast cancer screening; Vietnamese; Korean; Chinese; breast cancer; Asian American
12.  Overcoming Barriers to Cervical Cancer Screening Among Asian American Women 
Significant disparities in cervical cancer incidence and mortality exist among ethnic minority women, and in particular, among Asian American women. These disparities have been attributed primarily to differences in screening rates across ethnic/racial groups. Asian American women have one of the lowest rates of screening compared to other ethnic/racial groups. Yet Asian Americans, who comprise one of the fastest growing populations in the United States, have received the least attention in cancer control research. Studies suggest that various factors, including lack of knowledge, psychosocial and cultural beliefs, and access barriers, are associated with cervical cancer screening behaviors among Asian American women. Indeed, the few interventions that have been developed for Asian American women demonstrate that targeting these factors can yield significant increases in screening rates. It is important to note, however, that the effectiveness of educational interventions is often attenuated if access barriers are not adequately addressed. Hence, interventions that include key essential components, such as the use of community individuals as lay health workers, culturally-tailored and linguistically-appropriate educational materials, and navigation assistance to overcome access barriers, are more likely to be successful in enhancing screening rates. As the benefits of community-based cervical cancer prevention programs become more apparent, it will be essential to identify effective approaches for disseminating such programs more broadly. In conclusion, community-based cervical cancer screening programs have demonstrated promise in addressing existing cervical cancer disparities by increasing awareness and knowledge and promoting recommended screening behaviors. These findings will be instrumental in guiding future community-based programs to reduce cervical cancer health disparities among Asian American women.
PMCID: PMC3115728  PMID: 21687826
cervical cancer; screening; Asian Americans; disparities; cancer prevention; community-based; psychosocial beliefs; access barriers
13.  Evidence-Based Intervention to Reduce Access Barriers to Cervical Cancer Screening Among Underserved Chinese American Women 
Journal of Women's Health  2010;19(3):463-469.
The primary objective of the present study was to evaluate the effects of a community-based pilot intervention that combined cervical cancer education with patient navigation on cervical cancer screening behaviors among Chinese American women residing in New York City.
Chinese women (n = 134) who had not had a Pap test within the previous 12 months were recruited from four Asian community-based organizations (CBOs). Women from two of the CBOs received the intervention (n = 80) consisting of education, interaction with a Chinese physician, and navigation assistance, including help in identifying and accessing free or low-cost screening services. The control group (n = 54) received education delivered by Chinese community health educators and written materials on general health and cancer screening, including cervical cancer, the Pap test, and information about sites that provided free screening. Study assessments were obtained in-person at baseline and postintervention. Screening behavior was self-reported at 12-month postintervention and verified by medical staff.
In the 12-month interval following the program, screening rates were significantly higher in the intervention group (70%) compared to the control group (11.1%). Hierarchical logistic regression analyses indicated that screening behavior was associated with older age (OR = 1.08, 95% CI = 1.01–1.15, p < .05). In addition, women with poorer English language fluency (OR = 0.30, 95% CI = 0.10–0.89, p < .05) and who did not have health insurance were less likely to obtain screening (OR = 0.15, 95% CI = 0.02–0.96, p < .05). Among health beliefs, greater perceived severity of disease was positively associated with screening behavior (OR = 4.26, 95% CI = 1.01-18.04, p < .05).
Community-based programs that provide combined education and patient navigation may be effective in overcoming the extensive linguistic and access barriers to screening faced by Chinese American women.
PMCID: PMC2867551  PMID: 20156089
14.  Leucine-rich repeat kinase 2 (LRRK2)/PARK8 possesses GTPase activity that is altered in familial Parkinson’s disease R1441C/G mutants 
Journal of neurochemistry  2007;103(1):238-247.
Mutations in Leucine-rich repeat kinase 2 (LRRK2) are linked to the most common familial forms and some sporadic forms of Parkinson’s disease (PD). The LRRK2 protein contains two well-known functional domains, MAPKKK-like kinase and Rab-like GTPase domains. Emerging evidence shows that LRRK2 contains kinase activity which is enhanced in several PD-associated mutants of LRRK2. However, the GTPase activity of LRRK2 has yet to be formally demonstrated. Here, we produced and purified the epitope-tagged LRRK2 protein from transgenic mouse brain, and showed that purified brain LRRK2 possesses both kinase and GTPase activity as assayed by GTP binding and hydrolysis. The brain LRRK2 is associated with elevated kinase activity in comparison to that from transgenic lung or transfected cultured cells. In transfected cell cultures, we detected GTP hydrolysis activity in full-length as well as in GTPase domain of LRRK2. This result indicates that LRRK2 GTPase can be active independent of LRRK2 kinase activity (while LRRK2 kinase activity requires the presence of LRRK2 GTPase as previously shown). We further found that PD mutation R1441C/G in the GTPase domain causes reduced GTP hydrolysis activity, consistent with the altered enzymatic activity in the mutant LRRK2 carrying PD familial mutations. Therefore, our study shows the biochemical characteristics of brain-specific LRRK2 which is associated with robust kinase and GTPase activity. The distinctive levels of kinase/GTPase activity in brain LRRK2 may help explain LRRK2-associated neuronal functions or dysfunctions in the pathogenesis of PD.
PMCID: PMC2827244  PMID: 17623048
bacterial artificial chromosome transgenics; GTPase; kinase; Leucine-rich repeat kinase 2; Parkinson’s disease
15.  Systematic gene function prediction from gene expression data by using a fuzzy nearest-cluster method 
BMC Bioinformatics  2006;7(Suppl 4):S23.
Quantitative simultaneous monitoring of the expression levels of thousands of genes under various experimental conditions is now possible using microarray experiments. However, there are still gaps toward whole-genome functional annotation of genes using the gene expression data.
In this paper, we propose a novel technique called Fuzzy Nearest Clusters for genome-wide functional annotation of unclassified genes. The technique consists of two steps: an initial hierarchical clustering step to detect homogeneous co-expressed gene subgroups or clusters in each possibly heterogeneous functional class; followed by a classification step to predict the functional roles of the unclassified genes based on their corresponding similarities to the detected functional clusters.
Our experimental results with yeast gene expression data showed that the proposed method can accurately predict the genes' functions, even those with multiple functional roles, and the prediction performance is most independent of the underlying heterogeneity of the complex functional classes, as compared to the other conventional gene function prediction approaches.
PMCID: PMC1780124  PMID: 17217516
16.  Mutations That Affect Dimer Formation and Helicase Activity of the Hepatitis C Virus Helicase 
Journal of Virology  2001;75(1):205-214.
Interaction between viral proteins is necessary for viral replication and viral particle assembly. We used the yeast two-hybrid assay to identify interactions among all the mature proteins of the hepatitis C virus. The interaction between NS3 and NS3 was one of the strongest viral protein-protein interactions detected. The minimal region required for this interaction was mapped to a specific subdomain of 174 amino acids in the N terminus of the helicase region. Random mutations in the minimal region were generated by PCR, and mutants that failed to interact with a wild-type minimal fragment were isolated using the yeast two-hybrid assay as a screen. Three of these mutations resulted in a reduction or a loss of interaction between helicases. Analytical gel filtration showed that in the presence of an oligonucleotide, wild-type helicases form dimers whereas the mutants remain mostly monomeric. All three mutants were partially or almost inactive when assayed for helicase activity in vitro. Mixing a mutant helicase (Y267S) with wild-type helicase did not dramatically affect helicase activity. These data indicate that dimerization of the helicase is important for helicase activity. The mutations that reduce self-association of the helicase may define the key residues involved in NS3-NS3 dimerization.
PMCID: PMC113914  PMID: 11119590

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