Emergence of dengue hemorrhagic fever in French Antilles. 3 initial fatal cases in Guadeloupe

BACKGROUND: Two outbreaks of dengue hemorrhagic fever occurred in Guadeloupe (French West Indies) in successive epidemics in 1994 and 1995. The first outbreak was caused by DEN-2 virus and the second by DEN-1. CASE REPORTS: Seven life-threatening infections (WHO grade 3/4) were identified. Three previously healthy adults (including two brothers) died. Autopsy reports (2 patients) disclosed hemorrhagic serous effusions, disseminated intravascular coagulation, and in one case a spontaneous spleen rupture. DISCUSSION: Dengue fever is an emerging disease. Its severe hemorrhagic form tends to an uprising incidence and can no longer be considered a disease limited to children in Far-Eastern Asia. Fatalities may occur very suddenly and unexpectedly, even in optimal health care settings, in healthy adults living or travelling in endemic areas, notably the Caribbean.     

Pneumatic flow switching on centrifugal microfluidic platforms in motion

This paper describes a flow switching technique applicable to centrifugal microfluidic platforms, using a regulated stream of compressed gas. This pneumatic flow switching technique allows for flow control at a T-shaped junction between one inlet channel and two outlet channels. This technique provides a noncontact, robust, and efficient method for switching the direction of fluid flow while a disk is rotating at relatively low frequencies. The switching operation can be implemented reproducibly with applied gas flow rates between 17 and 58 L min(-1) and rotational frequencies between 400 rpm (6.6 Hz) and 1200 rpm (20 Hz).     

The supercooling and high temperature stupor points of the adult lesser mealworm Alphitobius diaperinus(Coleoptera: Tenebrionidae)

Potential thermobiological limits in adult lesser mealworms Alphitobius diaperinus were assessed during winter by measuring individual supercooling points (SCP) and thermostupor points (TSP). Two experimental conditions were tested: (i) SCP and TSP measured at 100% r.h.; (ii) SCP with specimens which survive to the TSP at 0% r.h.. The absolute temperature range compatible with life between the two limits SCP and TSP, termed thermobiological span (TBS), was calculated in both conditions.

The potential adaptive capacity to withstand cooling and overheating is: (i) at 100% r.h., mean TSP=46.7°C (SD±0.67); mean SCP=−9.4°C (SD±1.81); absolute TBS 56.1°C; (ii) at 0% r.h., mean TSP=47.4°C (SD±0.61); mean SCP=−12.3°C (SD±2.5); mean TBS 59.7°C (SD±2.43). The TSP at 0% r.h. is reached with a loss of 3.84% in fresh weight vs 1.15% at 100% r.h.. The difference in the SCP (females=2.1°C; males=5.4°C) obtained in dry or moist conditions could also be explained by the influence of the heat shock preceding the SCP measured at 0% r.h. A decrease of water content may increase the osmolarity of the body fluid and thus the supercooling capacity and could be an adaptation to avoid freezing. Supercooling capacity allows adults to survive in areas where freezing temperatures may occur in poultry houses and more specially during the winter litter removals when adult beetles migrate and overwinter in the soil floor or in insulation materials of the building walls. The heat tolerance capacity is mainly ruled by the physiological and behavioural adaptations of this species. Our results suggest that the adult population of A. diaperinus could be controlled by increasing the temperature above 48°C.     

Structure-based protein engineering efforts with a monomeric TIM variant: the importance of a single point mutation for generating an active site with suitable binding properties

A monomeric variant of triosephosphate isomerase (TIM) witha new engineered binding groove has been characterized further.In this variant (ml8bTIM), the phosphate binding loop had beenshortened, causing the binding site to be much more extended.Here, it is reported that in the V233A variant of ml8bTIM (A-TIM),three important properties of the wild-type TIM active sitehave been restored: (i) the structural properties of loop-7,(ii) the binding site of a conserved water molecule betweenloop-7 and loop-8 and (iii) the binding site of the phosphatemoiety. It is shown that the active site of A-TIM can bind TIMtransition state analogs and suicide inhibitors competently.It is found that the active site geometry of the A-TIM complexesis less compact and more solvent exposed, as in wild-type TIM.This correlates with the observation that the catalytic efficiencyof A-TIM for interconverting the TIM substrates is too low tobe detected. It is also shown that the A-TIM active site canbind compounds which do not bind to wild-type TIM and whichare completely different from the normal TIM substrate, likea citrate molecule. The binding of this citrate molecule isstabilized by hydrogen bonding interactions with the new bindinggroove.     

Effects of dry period energy intake on insulin resistance,metabolic adaptation,and production responses in transition dairy cows on grass silage–based diets

High energy intake in the dry period has reportedly had adverse effects on mobilization of body reserves, dry matter intake, and productivity of dairy cows. We investigated whether grass silage (GS) fed ad libitum (high energy intake, HEI; 141% of daily metabolizable energy requirements) in an 8-wk dry period affects metabolic adaptation—specifically, peripheral insulin resistance—compared with a total mixed ration consisting of GS, wheat straw, and rapeseed meal (55/40/5%; controlled energy intake, CEI; 108% of metabolizable energy/d) fed ad libitum. Multiparous Ayrshire dairy cows (n = 16) were used in a randomized complete block design until 8 wk after parturition. Commercial concentrates were fed 1 and 2 kg/d during the last 10 to 6 and 5 to 0 d before the expected calving date, respectively. Postpartum, a similar lactation diet with ad libitum access to GS and increasing concentrate allowance (maximum of 16 kg/d) was offered to all. The HEI group gained more body weight and had higher plasma insulin, glucose, and β-hydroxybutyrate concentrations than the CEI group prepartum. Postpartal plasma glucose tended to be higher and milk yield was greater from wk 5 onward for HEI compared with CEI cows. An intravenous glucose tolerance test (IVGTT) was performed at ?13 ± 5 d and 9 ± 1 d relative to calving. The HEI cows had greater insulin response to glucose load and smaller area under the response curve for glucose than CEI cows in prepartal IVGTT. Thus, compensatory insulin secretion adapted to changes in insulin sensitivity of the peripheral tissues, preserving glucose tolerance of HEI cows. Higher insulin levels were needed in HEI cows than in CEI cows to elicit a similar decrement of nonesterified fatty acid concentration in prepartal IVGTT, suggesting reduced inhibition of lipolysis by insulin in HEI cows before parturition. In conclusion, high energy intake of moderately digestible GS with low concentrate feeding in the close-up dry period did not have adverse effects on metabolic adaptation, insulin sensitivity, and body mobilization after parturition. Instead, this feeding regimen was more beneficial to early-lactation performance than GS-based total mixed ration diluted with wheat straw.