Variable selection in joint frailty models of recurrent and terminal events

Recurrent event data are commonly encountered in biomedical studies. In many situations, they are subject to an informative terminal event, for example, death. Joint modeling of recurrent and terminal events has attracted substantial recent research interests. On the other hand, there may exist a large number of covariates in such data. How to conduct variable selection for joint frailty proportional hazards models has become a challenge in practical data analysis. We tackle this issue on the basis of the “minimum approximated information criterion” method. The proposed method can be conveniently implemented in SAS Proc NLMIXED for commonly used frailty distributions. Its finite-sample behavior is evaluated through simulation studies. We apply the proposed method to model recurrent opportunistic diseases in the presence of death in an AIDS study.     

The extrapituitary prolactin promoter polymorphism is associated with rheumatoid arthritis and anti-CCP antibodies in Mexican population

Prolactin (PRL) is a hormone–cytokine that has been involved in autoimmunity due to its immunoregulatory and lymphoproliferative effects. It is produced by various extrapituitary sites including immune cells, under control of a superdistal promoter that contains a single nucleotide polymorphism − 1149 G/T previously associated with rheumatoid arthritis (RA) susceptibility in European population. The aim of this study was to investigate the association of the extrapituitary PRL − 1149 G/T promoter polymorphism with clinical parameters, clinical activity and disability indices in RA patients from Western Mexico and to analyze the PRL mRNA expression according to the PRL − 1149 G/T promoter polymorphism in total leucocytes from RA patients and controls. We conducted a case–control study that included 258 RA patients and 333 control subjects (CS). The DNA samples were genotyped using the PCR–RFLP method and the PRL mRNA expression was determined by quantitative real time PCR. PRL serum levels and antibodies to cyclic citrullinated peptides (anti-CCP) were measured with ELISA. We found significant differences in the genotype (p = 0.022) and allelic (p = 0.046) distribution of the polymorphism between RA patients and control subjects. According to the dominant genetic model, there is an association between the T allele (GT + TT genotypes) and decreased RA susceptibility in comparison to the G allele carriers (GG genotype) (OR 0.64, 95% CI 0.45–0.92; p = 0.011). The T allele carriers (GT + TT genotypes) had lower titers of anti-CCP antibodies in comparison to the G allele carriers (GG genotype) (median, 66 U/mL vs. 125 U/mL; p = 0.03). Furthermore, the GG homozygotes had higher PRL mRNA expression in comparison to the GT heterozygotes, and this latter with respect to the TT homozygotes, in both groups (RA: 1 > 0.72 > 0.19; CS: 1 > 0.54 > 0.28). However, PRL serum levels were similar in both groups. Our results suggest that the PRL − 1149 T allele is a genetic marker for decreased RA susceptibility and is associated with lower titers of anti-CCP antibodies in Mexican population. We also suggest influence of genotype upon PRL mRNA expression.     

Beliefs Underlying Dog Owners' Health Care Behaviors: Results from a Large,Self-Selected,Internet Sample

ABSTRACT

Various behaviors must be performed by owners to promote good health for their dogs. The aim in this study was to use the results of an online survey, completed by 1,016 self-selected, Australian dog owners, to investigate relationships between demographic factors, beliefs, dog–owner relationship variables, and the performance of health-promoting behaviors. Specific behaviors examined included the provision of annual vaccinations and health checkups by a veterinarian, regular grooming and exercise, and the provision of a nutritionally balanced diet. Reported compliance was high in the self-selected sample, ranging between 77.8% for annual vaccinations and 98.8% for the provision of a nutritious diet. Regression analyses revealed that all of the behaviors we measured could be predicted from beliefs relating to health care practices and dog–owner relationship variables independently of demographic factors. The extent of dog and owner interactions, as well as the extent to which owners perceived important others to be supportive of the behaviors, emerged as particularly important variables. These statistically robust findings have implications for campaigns encouraging pet health promotion by owners.     

Homelessness and dog ownership: an investigation into animal empathy,attachment, crime,drug use,health and public opinion

Abstract

A sample of 51 homeless people in Cambridge, UK completed a questionnaire featuring adapted Animal Empathy and Companion Animal Bonding Scales. Concepts of crime, drug use, and health matters amongst the homeless, both dog owning and non-dog owning, were investigated, as well. Ninety members of the general public completed a similar questionnaire which sought their opinions on homeless people who own dogs. There was a highly significant difference (p < 0.01) between the homeless and the securely housed on their animal empathy and attachment scores, with the homeless sample displaying higher values. Gender and dog ownership status had no effect on these scores. A near significant result (U = 2, n₁ = 13, n₂ = 58, p = 0.06) was revealed for animal empathy scores of those who gave money to dog-owning homeless people and those who gave to non-dog owning homeless people. Of the public respondents, women were significantly more likely to show concern for a homeless person's dog's welfare than men (X²₍₁₎ = 8.5, p < 0.01), and of the homeless respondents, non-dog owners were significantly more likely than dog owners to believe that having a dog helped initiate conversations with the public (X²₍₁₎ = 4.0, p < 0.05). Highly significant differences (U = 10, n₁ = 31, n₂ = 20, p < 0.01) were found for medical care use between the dog-owning and non-dog owning homeless, and health scores showed a reversed trend compared to that expected for the general population, with dog owners scoring lower than non-dog owners.     

Microbicide surface nano-structures

Abstract

The prevention of infectious diseases is a global challenge where multidrug-resistant bacteria or “superbugs” pose a serious threat to worldwide public health. Microtopographic surfaces have attracted much attention as they represent a biomimetic and nontoxic surface antibacterial strategy to replace biocides. The antimicrobial effect of such natural and biomimetic surface nanostructures involves a physical approach which eradicates bacteria via the structural features of the surfaces without any release of biocides or chemicals. These recent developments present a significant proof-of-concept and a powerful tool in which cellular adhesion and death caused by a physical approach, can be controlled by the micro/nanotopology of such surfaces. This represents an innovative direction of development of clean, effective and nonresistant antimicrobial surfaces. The minireview will cover novel approaches for the construction of nanostructures on surfaces in order to create antimicrobial surface in an environmentally friendly, nontoxic manner.     

Seasonal Variation in Human Salivary Cortisol Concentration

Measurement of cortisol concentration can contribute important information about an individual's ability to adjust to various environmental demands of both physical and psychosocial origin. However, one uncertainty that affects the possibilities of correctly interpreting and designing field studies is the lack of observations of the impact of seasonal changes on cortisol excretion. For this reason, the month‐to‐month changes in diurnal cortisol concentration, the awakening cortisol response (ACR), maximum morning concentration, and fall during the day were studied in a group of 24 healthy men and women 32 to 61 yrs of age engaged in active work. On one workday for 12 consecutive months, participants collected saliva at four time points for determination of cortisol: at awakening, +30 min, +8 h, and at 21:00 h. Data were analyzed by a repeated measures design with month (12 levels) and time‐of‐day (4 levels) as categorical predictors. Cortisol concentrations were analyzed on a log scale. The diurnal pattern of cortisol was similar across months (interaction between month and time of day: p>0.4). The main effects of month and time‐of‐day were statistically significant (p <0.001). Highest concentrations were observed in February, March, and April, and lowest concentrations were observed in July and August. There were no statistically significant effects in any of the other measures, or between men and women. In conclusion, a seasonal variation in salivary cortisol concentrations was detected in an occupationally active population. Thus, seasonal variation needs to be taken into account when designing and evaluating field studies and interventions and when making comparisons across studies.     

Assessing changes in oral health‐related quality of life and its factors in community‐dwelling older Brazilians

doi: 10.1111/j.1741‐2358.2012.00656.x Assessing changes in oral health‐related quality of life and its factors in community‐dwelling older Brazilians Objective: To describe changes in oral health‐related quality of life and to evaluate the associations of these changes in community‐dwelling older people. Materials and methods: In this longitudinal study a representative sample of 872 older people, living in Brazil, was evaluated during 2004. The follow‐up was carried out during 2008, with 587 older persons evaluated. A questionnaire assessing socio‐demographic information, health history, oral health‐impact profile and number of natural teeth was used. Changes in oral health‐related quality of life were categorized as improvement or deterioration. Data analysis was performed using a hierarchical approach based in a conceptual framework. A hierarchal approach was carried out using Poisson regressions. Results: Older persons living in rural areas, those who reported brushing once a day or less and older persons with fewer natural teeth had an increased chance of reporting deterioration in oral health‐related quality of life. Women and participants who received a minimum wage of less than US$219.50 were more likely to report improvement in oral health‐related quality of life. Conclusion: The results of this study suggest that changes in the oral health‐related quality of life are influenced by many of the variables that were included in the conceptual framework.