Picrotoxin-diazepam interaction in a behavioural schedule of differential reinforcement of low rates

Summary In rats working in a behavioural schedule of differential reinforcement of low rates (6 or 10 sec), picrotoxin (1 mg kg^–1) decreased the number of premature responses and increased (in DRL 10 sec only) the number of rewarded responses. The effect of picrotoxin was antagonized by diazepam (2 mg kg^–1). In contrast to picrotoxin, strychnine (1.5 mg kg^–1) increased the number of premature responses.This work was supported by a grant of I.N.S.E.R.M. (ATP 39-76-71).     

小鼠腔前卵泡卵母细胞的体外培养、体外成熟和体外受精研究

小鼠腔前卵泡在体外生长过程中，于培养液中添加血清，以及ＦＳＨ和胰岛素均对小鼠腔前卵泡的体外生长、体外成熟、体外受精起促进作用，其中以胰岛素的效果最为显著，腔前卵泡的体外成熟率和体外受精率可达６９．４％和８０．６％，但是体外受精后的体外发育率低于添加ＦＳＨ的试验组，表明ＦＳＨ有益于卵母细胞生长过程中细胞质的成熟。单层培养的卵巢颗粒细胞对腔前卵泡的体外生长也具有促进作用。将体外受精后发育至２—细胞的胚胎移植入受体鼠，胚胎可以正常着床发育。同时，卵母细胞的核仁和线粒体在培养过程中也发生相应的变化。     

Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation.

Recent interpretations of Himalayan-Tibetan tectonics have proposed that channel flow in the middle to lower crust can explain outward growth of the Tibetan plateau, and that ductile extrusion of high-grade metamorphic rocks between coeval normal- and thrust-sense shear zones can explain exhumation of the Greater Himalayan sequence. Here we use coupled thermal-mechanical numerical models to show that these two processes-channel flow and ductile extrusion-may be dynamically linked through the effects of surface denudation focused at the edge of a plateau that is underlain by low-viscosity material. Our models provide an internally self-consistent explanation for many observed features of the Himalayan-Tibetan system.     

Evolution and transmission of stable CTL escape mutations in HIV infection.

Increasing evidence indicates that potent anti-HIV-1 activity is mediated by cytotoxic T lymphocytes (CTLs); however, the effects of this immune pressure on viral transmission and evolution have not been determined. Here we investigate mother-child transmission in the setting of human leukocyte antigen (HLA)-B27 expression, selected for analysis because it is associated with prolonged immune containment in adult infection. In adults, mutations in a dominant and highly conserved B27-restricted Gag CTL epitope lead to loss of recognition and disease progression. In mothers expressing HLA-B27 who transmit HIV-1 perinatally, we document transmission of viruses encoding CTL escape variants in this dominant Gag epitope that no longer bind to B27. Their infected infants target an otherwise subdominant B27-restricted epitope and fail to contain HIV replication. These CTL escape variants remain stable without reversion in the absence of the evolutionary pressure that originally selected the mutation. These data suggest that CTL escape mutations in epitopes associated with suppression of viraemia will accumulate as the epidemic progresses, and therefore have important implications for vaccine design.     

Aerodynamic force generation of an insect-inspired flapper actuated by a compressed unimorph actuator

We examined experimentally the flapping performance in terms of aerodynamic force generation of an insect-inspired flapper actuated by both of original LIPCA and compressed LIPCA. Flapping tests for two artificial wing shapes of horse botfly and hawk moth were conducted at the wing rotation angle of 60° and a flapping frequency range from 6 Hz to 12 Hz to find the optimum flapping frequency and to investigate the effect of compressed LIPCA and wing shape on the force generation. Flapping tests in the vacuum were also undertaken to measure the induced inertia force. The aerodynamic force was calculated by subtracting the inertia force from the total force measured in the air. It was found that the average inertia force was relatively small when compared with the average total force. The use of the compressed LIPCA could significantly improve the flapping angle of the flapper from 110° to 130° （18.2% increase） resulting in 24.5% increase in the average aerodynamic force. It was also found that flapper with hawk moth wings could produce larger force than the flapper with horse botfly wings.     

Avian flu: isolation of drug-resistant H5N1 virus

The persistence of H5N1 avian influenza viruses in many Asian countries and their ability to cause fatal infections in humans have raised serious concerns about a global flu pandemic. Here we report the isolation of an H5N1 virus from a Vietnamese girl that is resistant to the drug oseltamivir, which is an inhibitor of the viral enzyme neuraminidase and is currently used for protection against and treatment of influenza. Further investigation is necessary to determine the prevalence of oseltamivir-resistant H5N1 viruses among patients treated with this drug.