Tulane University

About: Tulane University is a education organization based out in New Orleans, Louisiana, United States. It is known for research contribution in the topics: Population & Blood pressure. The organization has 24478 authors who have published 47205 publications receiving 1944993 citations. The organization is also known as: University of Louisiana.

Addition of vildagliptin to insulin improves glycaemic control in type 2 diabetes

Abstract: Aims/hypothesis Type 2 diabetes is difficult to manage in patients with a long history of disease requiring insulin therapy. Moreover, addition of most currently available oral antidiabetic agents increases the risk of hypoglycaemia. Vildagliptin is a dipeptidyl peptidase-IV inhibitor, which improves glycaemic control by increasing pancreatic beta cell responsiveness to glucose and suppressing inappropriate glucagon secretion. This study assessed the efficacy and tolerability of vildagliptin added to insulin therapy in patients with type 2 diabetes.

Malaria parasite development in mosquitoes

Abstract: Mosquitoes of the genus Anopheles transmit malaria parasites to humans. Anopheles mosquito species vary in their vector potential because of environmental conditions and factors affecting their abundance, blood-feeding behavior, survival, and ability to support malaria parasite development. In the complex life cycle of the parasite in female mosquitoes, a process termed sporogony, mosquitoes acquire gametocyte-stage parasites from blood-feeding on an infected host. The parasites carry out fertilization in the midgut, transform to ookinetes, then oocysts, which produce sporozoites. Sporozoites invade the salivary glands and are transmitted when the mosquito feeds on another host. Most individual mosquitoes that ingest gametocytes do not support development to the sporozoite stage. Bottle-necks occur at every stage of the cycle in the mosquito. Powerful new techniques and approaches exist for evaluating malaria parasite development and for identifying mechanisms regulating malaria parasite-vector interactions. This review focuses on those interactions that are important for the development of new approaches for evaluating and blocking transmission in nature.

Deformation of the lamina cribrosa and anterior scleral canal wall in early experimental glaucoma.

Abstract: Purpose To test the hypothesis that pathophysiologic deformation of the lamina cribrosa and anterior scleral canal wall underlies the onset of confocal scanning laser tomography (CSLT)-detected optic nerve head (ONH) surface change in early experimental glaucoma. Methods Both eyes of four normal (two normal eyes) monkeys and four with early glaucoma (one eye with laser-induced IOP elevation, observed until the onset of CSLT-detected ONH surface change) were enucleated immediately after death and immersion fixed at IOP 0 mm Hg. In an additional four normal monkeys and five with early glaucoma, both eyes were cannulated, and IOP set to 10 mm Hg in one normal eye and either 30 or 45 mm Hg in the other (normal or early-glaucoma) eye. After 15 to 80 minutes of acute IOP elevation, these nine monkeys were perfusion-fixed. Within images of serial sagittal sections of the ONH tissues in all 17 monkeys, anterior lamina cribrosa position, laminar thickness, and scleral canal diameter were measured. For each parameter, differences between the two eyes of each monkey and between treatment groups were assessed by ANOVA. Results Within the eyes of the eight monkeys with IOP 0 mm Hg, the lamina cribrosa was posteriorly displaced and thicker and the scleral canal was enlarged at Bruch's membrane and at the anterior laminar insertion in the early-glaucoma eyes compared with the contralateral normal eyes (plastic deformation). Within the high-IOP normal eyes, the lamina cribrosa was posteriorly displaced compared with that in the low-IOP normal eyes, but there were no significant differences in laminar thickness or scleral canal diameter (normal compliance). Within the high-IOP early-glaucoma eyes, the lamina cribrosa was posteriorly displaced and thicker and the scleral canal enlarged, compared with both low-IOP normal eyes and high-IOP normal eyes (hypercompliant deformation). Differences in laminar position between the high-IOP early-glaucoma eyes and the contralateral low-IOP normal eyes (hypercompliant plus plastic deformation) were more than eight times greater than the differences between the high-IOP normal eyes and the contralateral low-IOP normal eyes (normal compliance). Conclusions Both plastic (permanent) and hypercompliant deformation of the lamina cribrosa and anterior scleral canal wall are present in young adult monkey eyes with early experimental glaucoma. These findings suggest that damage to the ONH connective tissues occurs early in the monkey model of experimental glaucoma.

A New Electrocardiographic Pattern Observed in Cerebrovascular Accidents

Abstract: An electrocardiographic pattern was encountered in patients with cerebrovascular accidents which consisted primarily of T waves of large amplitude and duration. Large U waves were often present which may fuse in part or entirely within the T wave. Because of the presence and fusion of the T and U waves, the prolonged Q-T interval associated with the pattern was most probably a Q-U interval.

Imputation of Missing Data When Measuring Physical Activity by Accelerometry

Abstract: Within the past several years, accelerometry has emerged as an important means of assessing the duration and intensity of physical activity and has served to define primary outcome measures in several observational (1,4,20) and experimental studies (6,7,11,15,17). It is currently being used in the large group-randomized Trial of Activity in Adolescent Girls (TAAG) to examine the effect of a school- and community-based intervention on physical activity in middle-school girls. The uniaxial accelerometer considered in this trial, the ActiGraph, formerly known as the Computer Science and Applications (CSA) and Manufacturing Technologies Inc. (MTI) (ActiGraph, LLC, Fort Walton Beach, FL) is a small (5 × 4 × 1.5 cm) and lightweight (45 g) device that captures vertical acceleration. Acceleration is sampled 10× s−1, and the data are summed over a user-specified time interval (e.g., 30 s, 1 min) and the summed value or activity “count” is stored in memory. Although the measurement protocols vary, most studies involve monitoring physical activity over several days to ensure reliable estimates of usual physical activity behavior and to account for potentially important differences in activity patterns on weekdays versus weekend days (19). Participants are typically instructed to wear the accelerometer during waking hours, except when bathing and showering. Data from accelerometers are summarized in numerous ways, including the mean total count per day (11) and the mean minutes per day spent in moderate or vigorous physical activity (using established count cut points to distinguish specific intensity levels). The analysis is complicated in that 1) activity levels vary among days of the week and times of day and 2) over multiple days of monitoring, missing data arising from removal of the monitor are a common occurrence. Although participant noncompliance accounts for a large fraction of the missing data, legitimate reasons for removing the monitor, such as complying with mandated sports league safety regulations or participation in water-related activity (for monitors that are not waterproof), also contribute to data loss. Thus, the timing and amount of data contributed by each individual vary. If summary statistics are computed using the observed data only, these statistics have the potential to be biased. For example, the total count for a given day clearly underestimates the true level of activity on days in which the monitor is worn only part of a day. Some researchers have tried to minimize this bias by computing summary statistics after excluding accelerometer data on days in which the monitor is worn only part of the day. These are called incomplete days of observation. This strategy, however, is not without issues. First, even after excluding days with, say, less than 8 h of wearing time, the number of hours the monitor is worn is still likely to vary. Moreover, if included days have intervals when the subject was awake but not wearing the monitor, then total activity will be underestimated. Second, this approach ignores possible differences in activity levels on complete days and incomplete days, making the estimated summary statistics from complete days subject to selection bias. This paper proposes an analytical approach whereby the observed data are used to help predict activity levels for segments of the day in which the monitor is not worn. The resultant data set is pseudo-complete in the sense that each individual will have either observed or imputed data for all segments of each day in which the monitor was intended to be worn. Summary statistics are then estimated from this pseudo-complete data set. This imputation strategy is analogous to imputing missing item responses on multi-item questionnaires. The literature contains numerous examples in which this treatment of item nonresponse has been found to reduce bias effectively (5,21). In the following section, accelerometer data collected during the feasibility phase of the TAAG trial are used to demonstrate the potential for bias in estimating physical activity when all observed data are used as well as when a subset of data that excludes incomplete days of monitoring is used. We then describe procedures for filling in missing data using single imputation through expectation maximization (EM) and multiple imputation (MI) (9,14). The remaining sections of the paper describe the design of a simulation study to assess the effectiveness of the imputation approaches, present its results, and discuss the effectiveness of imputation as a strategy for dealing with missing data in the context of accelerometry.