Reduced body weight in male Tspan8-deficient mice.

OBJECTIVE: The gene TSPAN8 was recently identified in a genome-wide association study as the most likely causal gene in a locus that was correlated with the risk of type 2 diabetes (T2D) in northern European individuals. To assess whether Tspan8 is the actual T2D-causal gene in this locus, we ablated its expression in mice and determined the consequences of this ablation on a multitude of metabolic traits. RESULTS: We found that genetic ablation of Tspan8 in mice results in a reduction (-15.6%) in the body weight of males fed a normal chow diet and that this deficiency results in a resistance to body weight gain (-13.7%) upon feeding a high fat and high carbohydrate diet. The differences in body weight could only be detected in male mice and were the consequence of both a decrease in fat deposition, and a decrease in lean body mass (16.9 and 11%, respectively). In spite of the significant body weight difference, no changes in fasting insulin and glucose levels could be detected in Tspan8 knockout mice, nor could we identify changes in the clearance of glucose or sensitivity to insulin in oral glucose tolerance test and intraperitoneal insulin sensitivity test studies, respectively. In addition, male Tspan8 knockout mice showed significantly lower bone mineral density and phosphorus levels (6.2 and 16.6%, respectively). Expression of Tspan8 in mouse was highest in digestive tissues, but virtually absent from the pancreas. In contrast, expression of human TSPAN8 was substantial in digestive tissues, as well as pancreatic cells. CONCLUSIONS: Our results argue for a role for Tspan8 in body-weight regulation in males, but do not show differences in T2D-associated traits that were anticipated from previous human genome-wide association studies. Differences in Tspan8 expression levels in mouse and human tissues suggest that Tspan8 could fulfill different or additional physiological functions in these organisms.

Laser nephelometric evaluation of albumin, IgG and alpha 2-macroglobulin: applications to the study of alterations of the blood-brain barrier.

Cerebrospinal fluid and serum levels of albumin, immunoglobulin G and alpha 2-macroglobulin were determined by laser nephelometer in various pathological conditions: Guillain-Barré syndrome amyotrophic lateral sclerosis, lumbar disc herniation. These proteins are different due to their molecular weight, spacial conformation, CSF and serum concentrations and their CSF/serum quotient reflects the status of the blood-brain barrier. In the subjects group comparisons, albumin quotient and IgG quotient show a significant differentiations. The linear regression of albumin quotient compared to alpha 2-macroglobulin quotient behaves differently in the individual groups. The protein CSF/serum quotients are helpful in distinguishing the causes of alterations in the blood-brain barrier.

Phase-conjugate Fizeau interferometer.

We describe a phase-conjugate interferometer that consists of a partially transmitting conventional mirror placed in front of and in close proximity to a phase-conjugate mirror. The interferometer is self-referencing, compact, and insensitive to environmental disturbances, provides twice the sensitivity of conventional (nonphase-conjugate) interferometers, and produces a direct representation of an incident wave front. We have constructed such a device using internally self-pumped phase conjugation in barium titanate and have used the device to characterize the wave front produced by an aberrated optical system.