Effects of halothane on mechanical response of skeletal muscle from malignant hyperthermia susceptible patients.

The purpose of this investigation was to compare the effects of halothane on malignant hyperthermia (MH) and normal isolated muscle bundle performance during isometric contraction and relaxation phases. Mechanical parameters were measured: peak tension (PT), time to peak tension (TPT) and positive peak of isometric tension derivative (+dP/dtmax) characterized the contraction phase. Half-relaxation time (RT1/2) and negative peak of isometric tension derivative (-dP/dtmax) characterized the relaxation phase. The ratio R = (+dP/dtmax)/(-dP/dtmax) was used to study the coupling between contraction and relaxation under isometric condition. In normal muscle, halothane increased PT by nearly 40% without altering TPT. The +dP/dtmax value increased concomitantly with the -dP/dtmax values, thus no changes in R was observed. In MH muscle, PT was first potentiated (0.5-1.0 vol% halothane) and then depressed (2.0-3.0 vol% halothane). TPT and +dP/dtmax were not altered whereas RT1/2 increased progressively with concomitant decrease in -dP/dtmax, thus R increased by nearly 40%. The amplitude of MH muscle contracture with stepwise concentrations of halothane was correlated with the increase of RT1/2 and R, and the decrease of -dP/dtmax. These results suggest that halothane alters the relaxation phase more than the contraction phase in MH human skeletal muscle compared to normal muscle.     

Impact of Annual Praziquantel Treatment on Urogenital Schistosomiasis in a Seasonal Transmission Focus in Central Senegal

In Sub-Saharan Africa, urogenital schistosomiasis remains a significant public health problem, causing 150.000 deaths/year with approximately 112 million cases diagnosed. The Niakhar district is a disease hotspot in central Senegal where transmission occurs seasonally with high prevalences. The aim of this study was to determine the effect of annual treatment over 3 years on the seasonal transmission dynamics of S. haematobium in 9 villages in the Niakhar district. Adults and children aged between 5 and 60 years were surveyed from 2011 to 2014. Urine samples were collected door-to-door and examined for S. haematobium eggs at baseline in June 2011, and all participants were treated in August 2011 with PZQ (40 mg/kg). After this initial examination, evaluations were conducted at 3 successive time points from September 2011 to March 2014, to measure the efficacy of the annual treatments and the rates of reinfection. Each year, during the transmission period, from July to November-December, malacological surveys were also carried out in the fresh water bodies of each village to evaluate the infestation of the snail intermediate hosts. At baseline, the overall prevalence of S. haematobium infection was 57.7%, and the proportion of heavy infection was 45.3%, but one month after the first treatment high cure rates (92.9%) were obtained. The overall infection prevalence and proportion of heavy infection intensities were drastically reduced to 4.2% and 2.3%, respectively. The level of the first reinfection in February-March 2012 was 9.5%. At follow-up time points, prevalence levels varied slightly between reinfection and treatment from 9.5% in June 2012 to 0.3% in March 2013, 11.2 in June 2013, and 10.1% April 2014. At the end of the study, overall prevalence was significantly reduced from 57.7% to 10.1%. The overall rate of infested Bulinid snails was reduced after repeated treatment from 0.8% in 2012 to 0.5% in 2013. Repeated annual treatments are suggested to have a considerable impact on the transmission dynamics of S. haematobium in Niakhar, due to the nature of the epidemiological system with seasonal transmission. Thus, to maintain this benefit and continue to reduce the morbidity of urogenital schistosomiasis, other approaches should be integrated into the strategy plans of the National program to achieve the goal of urogenital schistosomiasis elimination in seasonal foci in Senegal.