Seasonal changes and wind dependence of thermal conductance in dorsal fur from two small mammal species (Peromyscus leucopus and Microtus pennsylvanicus)

(1) We measured the thermal conductance of dorsal pelage from meadow voles (Microtus pennsylvanicus) and white-footed mice (Peromyscus leucopus) during summer and winter.

(2) Thermal conductance was lower in the winter pelage of both species, but the seasonal change was greater in meadow voles.

(3) The form of wind speed dependence was determined by fitting a nonlinear curve of the form a+bu^c to data recorded at five wind speeds. The most appropriate exponent c was between 0.908 and 0.987, depending on species and season. These values are common and suggest that thermal and dynamic forces are important.

不同保温措施对患儿全身麻醉后体温的影响

目的:探讨不同保温措施对患儿全身麻醉后体温的影响,以选择最佳的保温措施。方法:选择2016年1月-2017年6月我院300例择期需要手术的患儿,按照随机数字表法分为对照组(n=60)和实验组(n=240),实验组根据不同的保温措施分为输液输血加温组(A组)、身体包裹组(B组)、冲洗液加温组(C组)、加热毯组(D组),每组60例。所有患者术中均常规加盖棉被,室温控制在24~26℃,对照组不再采取另外的保温措施。观察并记录各组患儿在入室不同时间的鼻咽温和肛温。结果:A、C组鼻咽温和肛温随着时间的推移逐步下降,且入室90 min后较入室时明显降低,差异均有统计学意义(均P0.05);B组在入室后鼻咽温和肛温维持在比较稳定的水平(均P0.05);D组鼻咽温和肛温随着时间的推移逐步上升,在入室90 min后较入室时显著升高,差异具有统计学意义(均P0.05)。结论:首选加热毯保温能够维持全身麻醉的患儿体温正常,提高麻醉后的安全性,其次选身体包裹保温,必要时可联合应用多种保温措施。     

Composition and Biophysical Properties of Myelin Lipid Define the Neurological Defects in Galactocerebroside- and Sulfatide-Deficient Mice

Abstract: Oligodendrocytes and Schwann cell-specific proteins are assembled with a highly ordered membrane lipid bilayer to the myelin sheath of axons, which functions as an insulator and allows rapid saltatory conduction. We approached the question of the function of the CNS and PNS myelin-specific galactospingolipids cerebrosides and sulfatides by generating a ceramide galactosyltransferase null allelic mouse line ( cgt ^−/−). Galactocerebroside- and sulfatide-deficient myelin loses its insulating properties and causes a severe dysmyelinosis that is incompatible with life. Here, we describe the biochemical and biophysical analysis of the myelin lipid bilayer of cgt ^−/− mice. The lipid composition of CNS and PNS myelin of cgt ^−/− mice is seriously perturbed and the sphingolipid biosynthetic pathway altered. Nonhydroxy and hydroxy fatty acid-substituted glycosylceramides (GlcC) are synthesized by oligodendrocytes and sulfated GlcC in addition in Schwann cells. The monogalactosyldiglyceride fraction is missing in the cgt ^−/− mouse. This new lipid composition can be correlated with the biophysical properties of the myelin sheath. The deficiency of galactocerebrosides and sulfatides leads to an increased fluidity, permeability, and impaired packing of the myelin lipid bilayer of the internodal membrane system. The loss of the two glycosphingolipid classes causes the breakdown of saltatory conductance of myelinated axons in the cgt ^−/− mouse.     

林麝幼体的换毛序和胎毛、夏毛、冬毛的形态

被毛是哺乳动物最主要的特征之一,有关动物换毛序与环境关系的研究,是动物生态学研究的一个重要方面。从1853年Browne开始研究毛发结构以来,人们对毛发的形态学、分类学和种属关系等方面的研究已开展了大量工作,特别是随着电镜技术的应用,这些方面的工作在逐渐深入(曹汉民等,19