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1.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 35(6): 604-613, 2024 Feb 02.
Article in Chinese | MEDLINE | ID: mdl-38413021

ABSTRACT

OBJECTIVE: To quantitatively analyze the risk indicators of re-introduction of imported malaria in China and their weighting coefficients, so as to investigate the difference in the contribution of risk indicators included in the current risk assessment framework for re-introduction of imported malaria in China to the risk assessment of re-introduction of imported malaria. METHODS: Publications pertaining to the risk assessment framework for re-introduction of imported malaria in China that reported the risk indicators and their weighting coefficients were retrieved in PubMed, Web of Science, CNKI, Wanfang Data, and VIP with terms of "malaria", "re-introduction/re-transmission/re-establishment", "risk assessment/risk evaluation/risk prediction" from the inception of the database through 3 August 2023, and literature search was performed in Google Scholar to ensure the comprehensiveness of the retrieval. Basic characteristics of included studies were extracted using pre-designed information extraction forms by two investigators, and data pertaining to risk indicators of re-introduction of imported malaria were cross-checked by these two investigators. The risk indicators included in the risk assessment framework for re-introduction of imported malaria in China and their weighting coefficients were visualized with the Nightingale's rose diagrams using the software R 4.2.1, and the importance of risk indictors was evaluated with the frequency of risk indicators included in the risk assessment framework and the ranking of weighting coefficients of risk indicators. In addition, the capability of risk indicators screened by different weighting methods was compared by calculating the ratio of the maximum to the minimum of the weighting coefficients of the risk indicators screened by different weighting methods. RESULTS: A total of 2 138 publications were retrieved, and following removal of duplications and screening, a total of 8 publications were included in the final analysis. In these 8 studies, 8 risk assessment frameworks for re-introduction of imported malaria in China and 52 risk indicators of re-introduction of imported malaria were reported, in which number of imported malaria cases (n = 8) and species of malaria vectors were more frequently included in the risk assessment frameworks (n = 8), followed by species of imported malaria parasites (n = 6) and population density of local malaria vectors (n = 6), and species of local malaria vectors (n = 6), number of imported malaria cases (n = 5) and species of imported malaria parasites had the three highest weighting coefficients (n = 4). The weighting methods included expert scoring method, combination of expert scoring method and analytic hierarchy process, and combination of expert scoring method and entropy weight method in these 8 studies, and the ratios of the maximum to the minimum of the weighting coefficients of the risk indicators screened by the expert scoring method were 1.143 to 2.241, while the ratios of the maximum to the minimum of the weighting coefficients of the risk indicators screened by combination of the expert scoring method and analytic hierarchy process were 34.970 to 162.000. CONCLUSIONS: Number of imported malaria cases, species of imported malaria parasites, species of local malaria vectors and population density of local malaria vectors are core indicators in the current risk assessment framework for re-introduction of imported malaria in China. Combination of the expert scoring method and analytic hierarchy process is superior to the expert scoring method alone for weighting the risk indicators.


Subject(s)
Malaria , Humans , Malaria/epidemiology , Malaria/prevention & control , Risk Factors , Risk Assessment/methods , China/epidemiology , Databases, Factual
2.
Med J Malaysia ; 78(1): 20-24, 2023 01.
Article in English | MEDLINE | ID: mdl-36715186

ABSTRACT

INTRODUCTION: Healthcare workers (HCWs) were among the first to be fully vaccinated against SARS-CoV-2. However, the antibody responses to the vaccines and potential decline among Malaysian HCW are still unclear. The objective of this study is to follow-up anti-S antibody levels among HCW vaccinated with mRNA vaccine (BTN162b2) and inactivated vaccine (CoronaVac). MATERIALS AND METHODS: Plasma samples were collected prevaccination, 2 weeks and 6 months post-vaccination and tested for total immunoglobulin levels using ELISA method. RESULTS: A small percentage of HCW (2.2%, 15/677) had elevated anti-S antibody levels in their pre-vaccination plasma samples (median 20.4, IQR 5.8), indicating that they were exposed to SARS-CoV-2 infection prior to vaccination. The mRNA vaccine significantly increased anti-S levels of both previously infected and uninfected individuals to saturation levels (median 21.88, IQR.0.88) at 2 weeks postsecond dose of the vaccine. At 6 months post-vaccination, the antibody levels appeared to be maintained among the recipients of the mRNA vaccine. However, at this time point, anti-S antibody levels were lower in individuals given inactivated vaccine (median 20.39, IQR 7.31, n=28), and interestingly, their antibody levels were similar to anti-S levels in pre-vaccination exposed individuals. Antibody levels were not different between the sexes. CONCLUSION: Anti-S levels differ in individuals given the different vaccines. While further study is required to determine the threshold level for protection against SARSCoV- 2, individuals with low antibody levels may be considered for boosters.


Subject(s)
COVID-19 Vaccines , COVID-19 , Humans , Malaysia , Tertiary Care Centers , COVID-19/prevention & control , SARS-CoV-2 , Health Personnel , Vaccination , Vaccines, Inactivated
3.
J Biol Regul Homeost Agents ; 35(1): 131-140, 2021.
Article in English | MEDLINE | ID: mdl-33567807

ABSTRACT

Visceral artery aneurysm (VAA) is a rare and potentially life-threatening condition, defined as true artery aneurysms and pseudoaneurysms of splanchnic circulation and renal artery. This study reports our experience in the diagnosis and endovascular treatment of visceral artery aneurysms (VAAs) over a 10-year period. Between 2008 and 2018, a total of 24 VAAs in 21 patients were diagnosed by clinical symptoms and a combination of imaging techniques, such as Doppler ultrasound, computed tomography angiogram, and catheter angiogram. All patients underwent endovascular treatment to exclude aneurysms. Oral antiplatelet medicine was administered, and imaging examination was performed during follow-up. Technical success was achieved in all 21 patients, and no periprocedural complications occurred. Endovascular coiling alone was employed in 10 aneurysms. Coiling was combined with gelfoam in 2 aneurysms. Coiling was assisted by stent in 4 aneurysms. Covered stents were deployed in 8 aneurysms individually. Clinical symptoms disappeared or highly improved in all patients after treatment. None of the patients showed recurrent symptoms after discharge. However, two cases with new aneurysms after 6 and 8 months, respectively, and one case with in-stent thrombosis after 12 months were reported during follow-up. This study may justify the efficacy of percutaneous endovascular coil embolization and stent deployment. It also provides beneficial experience about how to choose appropriate various endovascular strategies based on both clinical symptoms and aneurysm anatomy condition.


Subject(s)
Aneurysm, False , Aneurysm , Endovascular Procedures , Aneurysm/diagnostic imaging , Aneurysm/therapy , Aneurysm, False/diagnostic imaging , Aneurysm, False/therapy , Embolization, Therapeutic , Humans , Retrospective Studies , Stents , Time Factors , Treatment Outcome , Viscera/diagnostic imaging
4.
Front Microbiol ; 8: 287, 2017.
Article in English | MEDLINE | ID: mdl-28382020

ABSTRACT

Polymerase basic protein 1 (PB1), the catalytic core of the influenza A virus RNA polymerase complex, is essential for viral transcription and replication. Dendritic cells (DCs) possess important antigen presenting ability and a crucial role in recognizing and clearing virus. MicroRNA (miRNA) influence the development of DCs and their ability to present antigens as well as the ability of avian influenza virus (AIV) to infect host cells and replicate. Here, we studied the molecular mechanism underlying the miRNA-mediated regulation of immune function in mouse DCs. We first screened for and verified the induction of miRNAs in DCs after PB1 transfection. Results showed that the viral protein PB1 down-regulated the expression of miR375, miR146, miR339, and miR679 in DCs, consistent with the results of H9N2 virus treatment; however, the expression of miR222 and miR499, also reduced in the presence of PB1, was in contrast to the results of H9N2 virus treatment. Our results suggest that PB1 enhanced the ability of DCs to present antigens, activate lymphocytes, and secrete cytokines, while miR375 over-expression repressed activation of DC maturation. Nevertheless, PB1 could not promote DC maturation once miR375 was inhibited. Finally, we revealed that PB1 inhibited the P-Jnk/Jnk signaling pathway, but activated the p-Erk/Erk signaling pathway. While inhibition of miR375 -activated the p-Erk/Erk and p-p38/p38 signaling pathway, but repressed the P-Jnk/Jnk signaling pathway. Taken together, results of our studies shed new light on the roles and mechanisms of PB1 and miR375 in regulating DC function and suggest new strategies for combating AIV.

5.
Eur J Clin Nutr ; 67(9): 961-5, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23860000

ABSTRACT

BACKGROUND/OBJECTIVES: In Hebei province, China, over six million people are potentially exposed to excessive iodine through consumption of high iodine underground drinking water and consumption of iodized salt. The aim of this study is to evaluate the contributions of drinking water and iodized salt on children's iodine nutrition in one area of Hebei province in order to refine strategies to correct the excessive iodine intake in these areas. SUBJECTS/METHODS: To investigate the relationships between iodine content in water, iodized salt and urinary iodine content (UIC) in children (8-10 years), we randomly sampled three towns with a known median water iodine (MWI) of 150-300 µg/l in Hengshui City, Hebei province and collected water, salt and urine samples. RESULTS: The median UIC was 518.1 µg/l, the overall MWI was 247.0 µg/l, and 83% of children sampled were found to have urinary iodine concentrations higher than the WHO criterion of 300 µg/l. There was a significant and positive correlation between the median UIC of the children and the MWI in the 12 villages where the children lived (Spearman R=0.79, P=0.002), but the UIC was not significantly correlated with the median salt intake (MSI) (Spearman R=-0.17, P=0.6). A multiple linear regression analysis indicated that 68.7% of the variability in median UIC is associated with variability in MWI in the 12 villages. CONCLUSIONS: Iodine in drinking water was identified to be the key contributor to this excessive iodine in children indicating that in these areas, intervention should focus on providing alternative drinking water supplies.


Subject(s)
Drinking Water/chemistry , Goiter/epidemiology , Iodine/administration & dosage , Iodine/adverse effects , Child , Child Nutritional Physiological Phenomena , China/epidemiology , Drinking Water/analysis , Female , Goiter/etiology , Humans , Iodine/urine , Male , Nutritional Status , Sodium Chloride, Dietary/administration & dosage , Water Supply
6.
Rom J Morphol Embryol ; 52(4): 1173-85, 2011.
Article in English | MEDLINE | ID: mdl-22203920

ABSTRACT

The sirtuin SIRT1, a class III NAD(+)-dependent protein histone deacetylase, is present throughout the body that involves cells of the central nervous system, immune system, cardiovascular system, and the musculoskeletal system. SIRT1 has broad biological effects that affect cellular metabolism as well as cellular survival and longevity that can impact both acute and chronic disease processes that involve neurodegenerative disease, diabetes mellitus, cardiovascular disease, and cancer. Given the intricate relationship SIRT1 holds with a host of signal transduction pathways ranging from transcription factors, such as forkhead, to cytokines and growth factors, such as erythropoietin, it becomes critical to elucidate the cellular pathways of SIRT1 to safely and effectively develop and translate novel avenues of treatment for multiple disease entities.


Subject(s)
Cellular Senescence , Sirtuin 1/metabolism , Translational Research, Biomedical , Animals , Cell Survival , Cytoprotection , Humans , Oxidative Stress
7.
Biometrics ; 65(4): 1052-62, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19302407

ABSTRACT

Recent studies have shown that grassland birds are declining more rapidly than any other group of terrestrial birds. Current methods of estimating avian age-specific nest survival rates require knowing the ages of nests, assuming homogeneous nests in terms of nest survival rates, or treating the hazard function as a piecewise step function. In this article, we propose a Bayesian hierarchical model with nest-specific covariates to estimate age-specific daily survival probabilities without the above requirements. The model provides a smooth estimate of the nest survival curve and identifies the factors that are related to the nest survival. The model can handle irregular visiting schedules and it has the least restrictive assumptions compared to existing methods. Without assuming proportional hazards, we use a multinomial semiparametric logit model to specify a direct relation between age-specific nest failure probability and nest-specific covariates. An intrinsic autoregressive prior is employed for the nest age effect. This nonparametric prior provides a more flexible alternative to the parametric assumptions. The Bayesian computation is efficient because the full conditional posterior distributions either have closed forms or are log concave. We use the method to analyze a Missouri dickcissel dataset and find that (1) nest survival is not homogeneous during the nesting period, and it reaches its lowest at the transition from incubation to nestling; and (2) nest survival is related to grass cover and vegetation height in the study area.


Subject(s)
Bayes Theorem , Biometry/methods , Birds , Models, Statistical , Age Factors , Animals , Female , Male , Population Dynamics , Statistics, Nonparametric , Survival Analysis
8.
Biom J ; 50(1): 58-70, 2008 Feb.
Article in English | MEDLINE | ID: mdl-17849386

ABSTRACT

When a sampling unit doesn't respond to a survey it is termed unit nonresponse. Unit nonresponse may have a dramatic affect on estimation results of interest. Using only those who responded to the survey to calculate the estimate may bias the estimate, known as nonresponse bias. Many approaches have been created in order to account for nonresponse. One such approach is to resample those nonrespondents in a second response "phase" (or more). We build a Bayesian hierarchical model that uses information from multiple response "phases" to estimate the phase specific response rates from I subdomains. This information is simultaneously used to estimate the success rates in those I subdomains. Conditional success rates are then estimated for the first phase respondents, second phase respondents, and nonrespondents (the third response phase). A relationship between these three sets of conditional success rates is incorporated into the model. This is done through a spatially dependent structure. The 1998 Missouri Turkey Hunting Survey is used to illustrate this methodology. The success rate estimates from nonrespondents have a significant impact on the overall success rate.


Subject(s)
Bayes Theorem , Bias , Data Collection , Models, Statistical , Animals , Humans , Missouri , Turkeys
9.
Histol Histopathol ; 22(11): 1251-67, 2007 11.
Article in English | MEDLINE | ID: mdl-17647198

ABSTRACT

Interest in the diverse biology of protein tyrosine phosphatases that are encoded by more than 100 genes in the human genome continues to grow at an accelerated pace. In particular, two cytoplasmic protein tyrosine phosphatases composed of two Src homology 2 (SH2) NH2-terminal domains and a C-terminal protein-tyrosine phosphatase domain referred to as SHP-1 and SHP-2 are known to govern a host of cellular functions. SHP-1 and SHP-2 modulate progenitor cell development, cellular growth, tissue inflammation, and cellular chemotaxis, but more recently the role of SHP-1 and SHP-2 to directly control cell survival involving oxidative stress pathways has come to light. SHP-1 and SHP-2 are fundamental for the function of several growth factor and metabolic pathways yielding far reaching implications for disease pathways and disorders such as diabetes, neurodegeneration, and cancer. Although SHP-1 and SHP-2 can employ similar or parallel cellular pathways, these proteins also clearly exert opposing effects upon downstream cellular cascades that affect early and late apoptotic programs. SHP-1 and SHP-2 modulate cellular signals that involve phosphatidylinositol 3-kinase, Akt, Janus kinase 2, signal transducer and activator of transcription proteins, mitogen-activating protein kinases, extracellular signal-related kinases, c-Jun-amino terminal kinases, and nuclear factor-kappaB. Our progressive understanding of the impact of SHP-1 and SHP-2 upon multiple cellular environments and organ systems should continue to facilitate the targeted development of treatments for a variety of disease entities.


Subject(s)
Cell Physiological Phenomena , Cell Proliferation , Inflammation/physiopathology , Intracellular Signaling Peptides and Proteins/physiology , Protein Tyrosine Phosphatase, Non-Receptor Type 6/physiology , Protein Tyrosine Phosphatases/physiology , Apoptosis/physiology , Humans , Inflammation/metabolism , Protein Tyrosine Phosphatase, Non-Receptor Type 11
10.
Br J Pharmacol ; 150(7): 839-50, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17339844

ABSTRACT

BACKGROUND AND PURPOSE: Clinical indications for erythropoietin (EPO) in the vascular system reach far beyond the treatment of anemia, but the development of EPO as a non-toxic agent rests heavily upon the cellular pathways controlled by EPO that require elucidation. EXPERIMENTAL APPROACH: We modulated gene activity and examined cellular trafficking of critical pathways during oxidative stress that may work in concert with EPO to protect primary cerebral endothelial cells (ECs) during oxidative stress, namely protein kinase B (Akt1), 14-3-3 protein, the Forkhead transcription factor FOXO3a. KEY RESULTS: Here, we show that preservation of ECs by EPO during oxygen-glucose deprivation (OGD) required the initial activation of the phosphatidylinositol 3-kinase (PI-3K) pathway through Akt1, since specific pharmacological blockade of Akt1 activity or gene silencing of Akt1 prevented EC protection by EPO. EPO subsequently involved a series of anti-apoptotic pathways to activate STAT3, STAT5, and ERK 1/2. Furthermore, EPO maintained the inhibitory phosphorylation and integrity of the 'pro-apoptotic' transcription factor FOXO3a, promoted the binding of FOXO3a to 14-3-3 protein and regulated the intracellular trafficking of FOXO3a. Additionally, gene silencing of FOXO3a during OGD significantly increased EC survival, but did not synergistically improve cytoprotection by EPO, illustrating that EPO relied upon the blockade of the FOXO3a pathway. CONCLUSIONS AND IMPLICATIONS: Our work defines a novel cytoprotective pathway in ECs that involves PI-3 K, STAT3, STAT5, ERK 1/2, 14-3-3 protein and FOXO3a, which can be targeted for the development of EPO as a clinically effective and safe agent in the vascular system.


Subject(s)
Endothelial Cells/drug effects , Erythropoietin/pharmacology , 14-3-3 Proteins/metabolism , Animals , Cell Hypoxia , Cell Survival/drug effects , Cells, Cultured , Endothelial Cells/metabolism , Forkhead Box Protein O3 , Forkhead Transcription Factors/metabolism , Glucose/deficiency , Male , Phosphatidylinositol 3-Kinases/metabolism , Protein Transport/drug effects , Proto-Oncogene Proteins c-akt/metabolism , Rats , Rats, Sprague-Dawley , STAT3 Transcription Factor/metabolism , STAT5 Transcription Factor/metabolism
11.
J Community Health ; 31(2): 94-112, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16737171

ABSTRACT

The objective was to learn about the hepatitis prevention behavior of relatively unacculturated North American Chinese adults, along with their knowledge, beliefs, and perceptions with regard to hepatitis, screening, and vaccination. Forty Chinese men and women, aged 18-64, were recruited from immigrant communities in Seattle, Washington, and Vancouver, British Columbia. Semi-structured interviews (Cantonese or Mandarin) were audiotaped, translated, transcribed verbatim, and coded. Open coding, axial coding, constant comparison methods, and QSR NUD*IST 5 software was used for analysis. Findings were validated using eight focus groups. Findings indicated that many interviewees lack accurate knowledge with regard to hepatitis, often confusing the different types. Perceived causes of hepatitis included potentially harmful food (e.g., fried foods or potentially contaminated foods), alcohol, contact with infected individuals, stress, and inadequate rest. Preventive strategies associated with Chinese health beliefs included the use of Chinese herbal medicine, maintaining a stress-free mind, strengthening the body's natural defenses, and getting enough sleep. Other preventive strategies were the practice of good hygiene, vaccination, and the avoidance of contact with infected persons. Vaccination was not seen as primary, as 65% of those who had heard of hepatitis vaccination did not cite it as a means for hepatitis prevention until asked. Also, participants lacked information about the types and purposes of hepatitis vaccination and were worried about side effects. In conclusion, any attempt to promote hepatitis testing and vaccination among the North American Chinese should take traditional beliefs and practices into consideration.


Subject(s)
Asian/education , Health Knowledge, Attitudes, Practice , Hepatitis/ethnology , Hepatitis/prevention & control , Adolescent , Adult , Asian/psychology , British Columbia , China/ethnology , Female , Hepatitis/diagnosis , Hepatitis/etiology , Herbal Medicine , Humans , Interviews as Topic , Male , Mass Screening/statistics & numerical data , Medicine, Chinese Traditional , Middle Aged , Northwestern United States , Vaccination/statistics & numerical data , Viral Hepatitis Vaccines
12.
Stat Med ; 25(2): 285-309, 2006 Jan 30.
Article in English | MEDLINE | ID: mdl-16381075

ABSTRACT

A Bayesian semi-parametric model is proposed to capture the interaction among demographic effects (age and gender), spatial effects (county) and temporal effects of colorectal cancer incidences simultaneously. In particular, an extension of multivariate conditionally autoregressive (CAR) processes to a partially informative Gaussian demographic spatial temporal CAR (DSTCAR) process for a spatial-temporal setting is proposed. The precision matrix of the Gaussian DSTCAR process is the Kronecker product of several components. The spatial component is modelled with a CAR prior. A pth order intrinsic autoregressive prior (IAR(p)) is implemented for the temporal component to estimate a smoothed and non-parametric temporal trend. The demographic component is modelled with a Wishart prior. Data analysis shows significant spatial correlation only exists in the age group of 50-59. Males and females in their 50s and 60s show fairly strong correlation. The hypothesis testing based on Bayes factor suggests that gender correlation cannot be ignored in this model.


Subject(s)
Bayes Theorem , Colorectal Neoplasms/epidemiology , Epidemiologic Methods , Adult , Age Factors , Aged , Female , Humans , Incidence , Iowa/epidemiology , Male , Middle Aged , Sex Factors
13.
Histol Histopathol ; 21(1): 103-24, 2006 01.
Article in English | MEDLINE | ID: mdl-16267791

ABSTRACT

In slightly over a period of twenty years, our comprehension of the cellular and molecular mechanisms that govern the Wnt signaling pathway continue to unfold. The Wnt proteins were initially implicated in viral carcinogenesis experiments associated with mammary tumors, but since this period investigations focusing on the Wnt pathways and their transmembrane receptors termed Frizzled have been advanced to demonstrate the critical nature of Wnt for the development of a variety of cell populations as well as the potential of the Wnt pathway to avert apoptotic injury. In particular, Wnt signaling plays a significant role in both the cardiovascular and nervous systems during embryonic cell patterning, proliferation, differentiation, and orientation. Furthermore, modulation of Wnt signaling under specific cellular influences can either promote or prevent the early and late stages of apoptotic cellular injury in neurons, endothelial cells, vascular smooth muscle cells, and cardiomyocytes. A number of downstream signal transduction pathways can mediate the biological response of the Wnt proteins that include Dishevelled, beta-catenin, intracellular calcium, protein kinase C, Akt, and glycogen synthase kinase-3beta. Interestingly, these cellular cascades of the Wnt-Frizzled pathways can participate in several neurodegenerative, vascular, and cardiac disorders and may be closely integrated with the function of trophic factors. Identification of the critical elements that modulate the Wnt-Frizzled signaling pathway should continue to unlock the potential of Wnt pathway for the development of new therapeutic options against neurodegenerative and vascular diseases.


Subject(s)
Apoptosis , Cardiovascular System/cytology , Cell Differentiation , Neurons/physiology , Signal Transduction/physiology , Wnt Proteins/physiology , Animals , Cardiovascular Diseases/physiopathology , Cardiovascular Physiological Phenomena , Frizzled Receptors/physiology , Humans , Nervous System/cytology , Nervous System/embryology , Nervous System Physiological Phenomena , Neurodegenerative Diseases/physiopathology , Wnt Proteins/chemistry
14.
Phys Rev Lett ; 95(16): 161301, 2005 Oct 14.
Article in English | MEDLINE | ID: mdl-16241780

ABSTRACT

We construct the general solution for nonextremal charged rotating black holes in five-dimensional minimal gauged supergravity. They are characterized by four nontrivial parameters: namely, the mass, the charge, and the two independent rotation parameters. The metrics in general describe regular rotating black holes, providing the parameters lie in appropriate ranges so that naked singularities and closed timelike curves (CTCs) are avoided. We calculate the conserved energy, angular momenta, and charge for the solutions, and show how supersymmetric solutions arise in a Bogomol'nyi-Prasad-Sommerfield limit. These have naked CTCs in general, but for special choices of the parameters we obtain new regular supersymmetric black holes or smooth topological solitons.

15.
Biometrics ; 61(3): 877-8, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16135044

ABSTRACT

The populations of many North American landbirds are showing signs of declining. Gathering information on breeding productivity allows early detection of unhealthy populations and helps develop good habitat-management practices. In this paper, we study the performance of the Bayesian model (He, 2003, Biometrics 59, 962-973) for age-specific nest survival rates with irregular visits. We find that the estimates are satisfactory except for the age-one survival rate. Usually the more days skipped between two visits, the more serious the underestimation of the age-one survival rate. We investigated the problem and developed three approaches to adjust for the underestimation bias. The simulation results show that the three approaches can significantly improve the estimation of the age-one survival rate.


Subject(s)
Bayes Theorem , Models, Statistical , Nesting Behavior/physiology , Songbirds/growth & development , Age Factors , Animals , North America , Songbirds/physiology
16.
Histol Histopathol ; 20(1): 299-315, 2005 01.
Article in English | MEDLINE | ID: mdl-15578447

ABSTRACT

Protein kinase B, also known as Akt, is a serine/threonine kinase and plays a critical role in the modulation of cell development, growth, and survival. Interestingly, Akt is ubiquitously expressed throughout the body, but its expression in the nervous system is substantially up-regulated during cellular stress, suggesting a more expansive role for Akt in the nervous system that may involve cellular protection. In this regard, a body of recent work has identified a robust capacity for Akt and its downstream substrates to foster both neuronal and vascular survival during apoptotic injury. Cell survival by Akt is driven by the modulation of both intrinsic cellular pathways that oversee genomic DNA integrity and extrinsic mechanisms that control inflammatory microglial activation. A series of distinct pathways are regulated by Akt that include the Forkhead family of transcription factors, GSK-3 beta, beta-catenin, c-Jun, CREB, Bad, IKK, and p53. Culminating below these substrates of Akt are the control of caspase mediated pathways that promote genomic integrity as well as prevent inflammatory cell demise. With further levels of progress in defining the cellular role of Akt, the attractiveness of Akt as a vital and broad cytoprotectant for both neuronal and vascular cell populations should continue to escalate.


Subject(s)
Brain/drug effects , Inflammation/drug therapy , Protein Serine-Threonine Kinases/drug effects , Proto-Oncogene Proteins/drug effects , Animals , Apoptosis/physiology , Carrier Proteins/metabolism , Cell Survival/drug effects , Forkhead Transcription Factors , Humans , Nuclear Proteins/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Phosphorylation , Protein Serine-Threonine Kinases/physiology , Proto-Oncogene Proteins/physiology , Proto-Oncogene Proteins c-akt , Transcription Factors/metabolism , bcl-Associated Death Protein
17.
Biom J ; 47(5): 721-39, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16385912

ABSTRACT

In the last thirty years, there has been considerable interest in finding better models to fit data for probabilities of conception. An important early model was proposed by Barrett and Marshall (1969) and extended by Schwartz, MacDonald and Heuchel (1980). Recently, researchers have further extended these models by adding covariates. However, the increasingly complicated models are challenging to analyze with frequentist methods such as the EM algorithm. Bayesian models are more feasible, and the computation can be done via Markov chain Monte Carlo (MCMC). We consider a Bayesian model with an effect for protected intercourse to analyze data from the California Women's Reproductive Health Study and assess the effects of water contaminants and hormones. There are two main contributions in the paper. (1) For protected intercourse, we propose modeling the ratios of daily conception probabilities with protected intercourse to corresponding daily conception probabilities with unprotected intercourse. Due to the small sample size of our data set, we assume the ratios are the same for each day but unknown. (2) We consider Bayesian analysis under a unimodality assumption where the probabilities of conception increase before ovulation and decrease after ovulation. Gibbs sampling is used for finding the Bayesian estimates. There is some evidence that the two covariates affect fecundability.


Subject(s)
Fertility , Fertilization , Models, Statistical , Reproductive Medicine/statistics & numerical data , Bayes Theorem , California , Contraception/statistics & numerical data , Female , Humans , Likelihood Functions , Probability , Reproductive Medicine/methods , Sampling Studies
18.
Stat Med ; 24(2): 249-67, 2005 Jan 30.
Article in English | MEDLINE | ID: mdl-15532076

ABSTRACT

In applying capture-recapture methods for closed populations to epidemiology, one needs to estimate the total number of people with a certain disease in a certain research area by using several lists with information of patients. Problems of lists error often arise due to mistyping or misinformation. Adopting the concept of tag-loss methodology in animal populations, Seber et al. (Biometrics 2000; 56:1227-1232) proposed solutions to a two-list problem. This article reports an interesting simulation study, where Bayesian point estimates based on improper constant and Jeffreys prior for unknown population size N could have smaller frequentist standard errors and MSEs compared to the estimates proposed in Seber et al. (2000). The Bayesian credible intervals based on the same priors also have super frequentist coverage probabilities while some of the frequentist confidence intervals procedures have drastically poor coverage. Seber's real data set on gestational diabetics is analysed with the proposed new methods.


Subject(s)
Bayes Theorem , Epidemiologic Methods , Models, Biological , Population Density , Computer Simulation , Diabetes, Gestational/epidemiology , Female , Humans , Male , New Zealand/epidemiology , Pregnancy
19.
Histol Histopathol ; 19(2): 495-504, 2004 04.
Article in English | MEDLINE | ID: mdl-15024710

ABSTRACT

Targeting essential cellular pathways that determine neuronal and vascular survival can foster a successful therapeutic platform for the treatment of a wide variety of degenerative disorders in the central nervous system. In particular, oxidative cellular injury can precipitate several nervous system disorders that may either be acute in nature, such as during cerebral ischemia, or more progressive and chronic, such as during Alzheimer disease. Apoptotic injury in the brain proceeds through two distinct pathways that ultimately result in the early externalization of membrane phosphatidylserine (PS) residues and the late induction of genomic DNA fragmentation. Degradation of DNA may acutely impact cellular survival, while the exposure of membrane PS residues can lead to microglial phagocytosis of viable cells, cellular inflammation, and thrombosis in the vascular system. Through either independent or common pathways, the Wingless/Wnt pathway and the serine-threonine kinase Akt serve central roles in the maintenance of cellular integrity and the prevention of the phagocytic disposal of cells "tagged" by PS exposure. By selectively governing the activity of specific downstream substrates that include GSK-3beta, Bad, and beta-catenin, Wnt and Akt serve to foster neuronal and vascular survival and block the induction of programmed cell death. Novel to Akt is its capacity to protect cells from phagocytosis through the direct modulation of membrane PS exposure. Intimately linked to the activation of Wnt signaling and Akt is the maintenance of mitochondrial membrane potential and the regulation of Bcl-xL, mitochondrial energy metabolism, and cytochrome c release that can lead to specific cysteine protease activation.


Subject(s)
Cell Membrane/metabolism , Mitochondria/metabolism , Neurons/metabolism , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins/metabolism , Animals , Apoptosis , Cell Division , Cell Survival , Cysteine Endopeptidases/metabolism , Cytochromes c/metabolism , Endopeptidases/metabolism , Enzyme Activation , Humans , In Situ Nick-End Labeling , Membrane Potentials , Microglia/metabolism , Models, Biological , Oxidative Stress , Phagocytosis , Phosphatidylserines/chemistry , Proto-Oncogene Proteins c-akt , Proto-Oncogene Proteins c-bcl-2/metabolism , Signal Transduction , Wnt Proteins , bcl-X Protein
20.
Biometrics ; 60(1): 50-9, 2004 Mar.
Article in English | MEDLINE | ID: mdl-15032773

ABSTRACT

Sampling units that do not answer a survey may dramatically affect the estimation results of interest. The response may even be conditional on the outcome of interest in the survey. If estimates are found using only those who responded, the estimate may be biased, known as nonresponse bias. We are interested in finding estimates of success rates from a survey. We begin by looking at two current Bayesian approaches to treating nonresponse in a hierarchical model. However, these approaches do not consider possible spatial correlations between domains for either success rate or response rate. We build a Bayesian hierarchical spatial model to explicitly estimate the success rate, response rate given success, and response rate given failure. The success rates in the domains of the survey are allowed to be spatially correlated. We also allow spatial dependence between domains in both response rate given success and response rate given failure. Spatial dependence is induced by a common latent spatial structure between the two conditional response rates. We use the 1998 Missouri Turkey Hunting Survey to illustrate this methodology. We find significant spatial correlation in the success rates and incorporating nonrespondents has an impact on the success rate estimates.


Subject(s)
Bayes Theorem , Animals , Animals, Wild , Bias , Biometry , Data Collection , Linear Models , Markov Chains , Missouri , Monte Carlo Method , Sampling Studies , Turkeys
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