Sleeping sickness and the brain

Recent progress in understanding the neuro-pathological mechanisms of sleeping sickness reveals a complex relationship between the trypanosome parasite that causes this disease and the host nervous system. The pathology of late-stage sleeping sickness, in which the central nervous system is involved, is complicated and is associated with disturbances in the circadian rhythm of sleep. The blood-brain barrier, which separates circulating blood from the central nervous system, regulates the flow of materials to and from the brain. During the course of disease, the integrity of the blood-brain barrier is compromised. Dysfunction of the nervous system may be exacerbated by factors of trypanosomal origin or by host responses to parasites. Microscopic examination of cerebrospinal fluid remains the best way to confirm late-stage sleeping sickness, but this necessitates a risky lumbar puncture. Most drugs, including many trypanocides, do not cross the blood-brain barrier efficiently. Improved diagnostic and therapeutic approaches are thus urgently required. The latter might benefit from approaches which manipulate the blood-brain barrier to enhance permeability or to limit drug efflux. This review summarizes our current understanding of the neurological aspects of sleeping sickness, and envisages new research into blood-brain barrier models that are necessary to understand the interactions between trypanosomes and drugs active against them within the host nervous system. Received 10 October 2001; received after revision 29 November 2001; accepted 5 December 2001     

传染病动力学的一个细胞自动机模型

由细胞自动机出发提出一个传染病流行的非线性动力学模型，由计算机数值模拟，应用自组织临界理论分析结果，发现发病率和治愈率均为５０％时存在着分界点。在分界点两侧，患病集团分布和传染持续时间分布分别服从指数律和幂律，免疫体的分布具有不同的分数维。     

中国女性低切全血比粘度正常参考值与地理因素的关系

收集了中国８６个地区４８７０例健康成年女性的低切全血比粘度正常参考值，并对其与海拔高度、纬度、年均相对湿度、年均气温、年降水量等５项地理因素之间的关系进行了研究，发现海拔高度是影响女性低切全血比粘度正常参考值最主要的因素，随着海拔高度的增大，女性低切全血比粘度正常参考值也逐渐增大．运用数学回归的方法，推导出了５个一元回归方程和１个多元回归方程，如果知道了中国某地的地理因素，就可用回归方程来估算这一地区女性低切全血比粘度正常参考值     

Renal effects of a high unsaturated fat diet in renal artery stenosis in rats

The renal effects of an unsaturated fat (UNSAT) diet in mild to moderate two-kidney, one-clip (2K1C) renovascular hypertension were evaluated. An UNSAT diet (37% by energy) prevented the development of hypertension compared to 2K1C rats fed a high saturated fat (SAT) (37% by energy) and a normal fat (CONTROL) (11% by energy) diet. Urinary sodium and fractional sodium excretion increased in 2K1C rats as compared to SHAM operated controls, regardless of the diet received. In the early weeks of the experiment (weeks 2–4 post-surgery to induce hypertension), an enhanced natriuresis occurred in the 2K1C UNSAT as compared to the 2K1C CONTROL and SAT diet groups. This resulted from an increase in the glomerular filtration rate (GFR in mls·min^–1) as measured using the single-injection [⁵¹Cr] EDTA method (2K1C UNSAT; 1.99±0.18 versus 2K1C SAT; 1.27±0.09, p<0.02; and versus SHAM CONTROL; 1.45×0.01; p<0.02). The increased GFR was not associated with alterations in effective renal plasma flow (ERPF) as measured using the single-injection [¹²⁵I] Na hippurate method. No differences in sodium excretion; GFR; ERPF or renal blood flow (microsphere technique) were noted between the 2K1C UNSAT and SAT diet groups at weeks 6–8 post-surgery, despite a continued antihypertensive effect of the UNSAT diet. Hence, the antihypertensive effect of an unsaturated fat diet in 2K1C renovascular hypertension in rats is associated with transient glomerular changes leading to an enhanced natriuresis.     

茶多酚的防癌抗衰作用研究

从绿茶中提取的茶多酚粗制品具有活性氧自由基清除作用,其活性比等量V_c高4.16倍。在模拟胃液条件下,能有效阻断强致癌性物质亚硝胺的合成。添加于鸡的饲食中时,茶多酚类物质可显著降低血脂含量。     

中国男性全血粘度（5．75s~（－1））正常值与地理因素的关系

分析了中国２２个地区１４８３例健康男性全血粘度（５．７５Ｓ－１）正常值与５项地理因素之间的关系，发现海拔高度是影响男性全血粘度（５．７５Ｓ－１）正常值最主要的因素，随着海拔高度的增大，男性全血粘度（５．７５Ｓ－１）正常值也逐渐增大．     

Rhythms of enzymatic activity in maternal and umbilical cord blood

The 24-h activity patterns of variouns enzymes were determined in human serum, red blood cells and white blood cells of maternal and umbilical cord blood. Blood was drawn from the brachial vein of mothers and from the umbilical cord within ten minutes after delivery. Corresponding blood specimens were obtained from 83 spontaneous labors, occurring at different hours over a period of 60 days. For each variable (variable=activity of a specific enzyme in one of the blood components) the results were grouped according to delivery hour, forming a 24-h pattern which was analyzed to elucidate time dependency. Five out of six corresponding maternal and fetal variables were similar with regard to pattern and peak time. The activity rhythms of glyceraldehyde-3-phosphate dehydrogenase and glucose phosphate isomerase in red blood cells of mothers and fetuses possessed a significant bimodal pattern. The activity rhythms of the latter enzyme in white blood cells and sera exhibited a significant 24-h period. Hexosaminidase activity exhibited a distinct 24-h rhythm in maternal white blood cells, but no significant rhythm could be detected in the fetal white blood cells. The activity of hexosaminidase showed, identical 24-h patterns in maternal and cord serum when analyzed by best fit cosine, and no significant time-dependency when analyzed by ANOVA.     

Neuronal control of brain microvessel function

Summary Cerebral capillary endothelium forms a barrier limiting and controlling the movement of ions and solutes between blood and brain. Recent anatomical, physiological and biochemical studies have suggested the possibility that capillary function may be directly controlled by neuronal structures. Alterations in neuronal systems involved in the regulation of microcirculation may account for microvascular dysfunctions which occur in different pathologic conditions.     

B→O blood conversion

To maintain a constant supply of “universal blood type”,or group O red blood cells,has benefit in specialized transfusion condition.In this study, α-galactosidase cDNA was cloned from Catimor coffee bean grown in Hainan island,China,by the RT-PCR method.We have constructed a vector for α-galactosidase cDNA expression and transferred α-galactosidase cDNA into Pichia pastoris GS115 cells by electroporation.The recombinant α-galactosidase(r-α-GalE)was purified by cation ion exchange chromatography.After studying the biochemical characters of r-α-GalE we have succeeded in converting human erythrocytes from group B to group O.The animal experiment showed that transfusion of enzymetically converted group O red blood cells(ECORBC)was perfectly safe.