A Cohort Study of a History of Gestational Diabetes Mellitus and the Risk of Incident Type 2 Diabetes in Louisiana Women

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications. It has been shown that a history of GDM is associated with an increased risk of incident type 2 diabetes in women. In this project, we aim to investigate 1) the trend of GDM incidence in Louisiana State University Health Care Services Division (LSUHCSD) hospital system during 1997 to 2009; 2) the race-specific association between a history of GDM and the risk of incident type 2 diabetes and how the risk changes over years after the index pregnancy. We conducted a retrospective study among women aged 13-50 years. Pregnancies, GDM cases and type 2 diabetes cases were identified by using the International Classification of Disease (ICD) -9 code from the Louisiana State University Hospital-Based Longitudinal Study (LSUHLS) database. The annual incidence of GDM and it standard error (SE) were calculated. Cox proportional hazards regression models were used to estimate the association of a history of GDM with the risk of incident type 2 diabetes. The association between previous GDM and the risk of type 2 diabetes in different postpartum periods was examined using logistic regression. The incidence of GDM increased in most years from 1997 to 2009 and reached a peak in 2002. The incidence of GDM increased with age and reached the peak at 35-39 years of age. Among the three study races, Asians had a significantly higher incidence of GDM than Whites and African Americans. Between 1990 and 2009, 1,142 GDM women and 18,856 non-GDM women presented their first record of pregnancy in the LSUHLS database. During a mean follow-up of 8.6 years, 1,067 women without a history of GDM and 327 women with a history of GDM developed type 2 diabetes. The multivariable-adjusted (age, smoking, income, postpartum body mass index (BMI), postpartum systolic blood pressure, and race) hazard ratio of type 2 diabetes suggested that a history of GDM is a strong predictor of subsequent type 2 diabetes among Louisiana women, especially among African American women. In addition, risk of type 2 diabetes was decreased by the time after the index delivery

Lytic cycle: A defining process in oncolytic virotherapy

The viral lytic cycle is an important process in oncolytic virotherapy. Most mathematical models for oncolytic virotherapy do not incorporate this process. In this article, we propose a mathematical model with the viral lytic cycle based on the basic mathematical model for oncolytic virotherapy. The viral lytic cycle is characterized by two parameters, the time period of the viral lytic cycle and the viral burst size. The time period of the viral lytic cycle is modeled as a delay parameter. The model is a nonlinear system of delay differential equations. The model reveals a striking feature that the critical value of the period of the viral lytic cycle is determined by the viral burst size. There are two threshold values for the burst size. Below the first threshold, the system has an unstable trivial equilibrium and a globally stable virus free equilibrium for any nonnegative delay, while the system has a third positive equilibrium when the burst size is greater than the first threshold. When the burst size is above the second threshold, there is a functional relation between the bifurcation value of the delay parameter for the period of the viral lytic cycle and the burst size. If the burst size is greater than the second threshold, the positive equilibrium is stable when the period of the viral lytic cycle is smaller than the bifurcation value, while the system has orbitally stable periodic solutions when the period of the lytic cycle is longer than the bifurcation value. However, this bifurcation value becomes smaller when the burst size becomes bigger. The viral lytic cycle may explain the oscillation phenomena observed in many studies. An important clinic implication is that the burst size should be carefully modified according to its effect on the lytic cycle when a type of a virus is modified for virotherapy, so that the period of the viral lytic cycle is in a suitable range which can break away the stability of the positive equilibria or periodic solutions. (C) 2012 Elsevier Inc. All rights reserved

Lifestyle Factors and Risk of Heart Failure: A Prospective Cohort Study

Heart failure (HF) has become a major health problem with its high prevalence, poor clinical outcomes, and large health-care costs. Compared with medical intervention, the prevention of HF through lifestyle approaches is free of side effect. Therefore, the prevention of HF through lifestyle approaches is of special interest. In this project, we aim to investigate 1) the association of different levels of occupational, commuting and leisure-time physical activity with HF risk; 2) the association of coffee consumption with HF risk; 3) the role of lifestyle factors in explaining the risk of HF; and 4) the association between antihypertensive drug treatment and HF risk with the association between engaging in a healthy lifestyle and HF risk. We conducted prospective studies among Finnish men and women who were 25 to 74 years of age and free of HF at baseline. Cox proportional hazards regression models were used to estimate the associations of interest. Partial population attributable risk was calculated to estimate the proportion of new HF cases occurring in this population that hypothetically could have been prevented if all subjects had certain health lifestyle factors. Our study results showed that 1) moderate and high levels of occupational or leisure-time physical activity are associated with a reduced risk of HF in both sexes; A simultaneous engagement in two or three types of physical activity showed a slightly stronger protective effect than participation in only one type of physical activity; 2) coffee consumption does not increase the risk of HF in Finnish men and women; In women, we observed an inverse association between low-to-moderate coffee consumption and the risk of HF; 3) maintaining a body mass index ¡Ü25, consuming vegetable ¡Ý3 times a week, abstaining from smoking and engaging in moderate or high level of physical activity were individually and jointly associated with a decreased risk of HF among both men and women; The relationship between the number of healthy lifestyle factors one engaged in and HF risk was dose-response; and 4) HF risk was lower in hypertensive patients who engaged in a healthy lifestyle but higher in hypertensive people using antihypertensive drug treatment