Functional magnetic resonance imaging based on changes in vascular space occupancy.

During brain activation, local control of oxygen delivery is facilitated through microvascular dilatation and constriction. A new functional MRI (fMRI) methodology is reported that is sensitive to these microvascular adjustments. This contrast is accomplished by eliminating the blood signal in a manner that is independent of blood oxygenation and flow. As a consequence, changes in cerebral blood volume (CBV) can be assessed through changes in the remaining extravascular water signal (i.e., that of parenchymal tissue) without need for exogenous contrast agents or any other invasive procedures. The feasibility of this vascular space occupancy (VASO)-dependent functional MRI (fMRI) approach is demonstrated for visual stimulation, breath-hold (hypercapnia), and hyperventilation (hypocapnia). During visual stimulation and breath-hold, the VASO signal shows an inverse correlation with the stimulus paradigm, consistent with local vasodilatation. This effect is reversed during hyperventilation. Comparison of the hemodynamic responses of VASO-fMRI, cerebral blood flow (CBF)-based fMRI, and blood oxygenation level-dependent (BOLD) fMRI indicates both arteriolar and venular temporal characteristics in VASO. The effect of changes in water exchange rate and partial volume contamination with CSF were calculated to be negligible. At the commonly-used fMRI resolution of 3.75 x 3.75 x 5 mm(3), the contrast-to-noise-ratio (CNR) of VASO-fMRI was comparable to that of CBF-based fMRI, but a factor of 3 lower than for BOLD-fMRI. Arguments supporting a better gray matter localization for the VASO-fMRI approach compared to BOLD are provided.     

安顺市区沙门氏菌环境污染调查

在贵州省安顺市１９８５年水型伤寒爆发流行后，为调查该市环境中沙门氏菌污染情况，我站于１９８６～１９８８年对市区所属医院和贯城河污水及部分食物的沙门氏菌进行了监测，共采集污水及食品６１９份，沙门氏菌阳性率为４１．８４％，分属Ａ、Ｂ、Ｃ、Ｄ、Ｅ１五个群１２个血清型，伤寒沙门氏菌经Ｖｉ噬菌体分型为Ｍ１型。纸片药敏试验为多重性耐药菌株。阐明了沙门氏菌流行的部分传播媒介途径。     

Quantification by ELISA of Aldrin/Dieldrin in river Nile water and tap water samples collected in Egypt

An indirect competitive ELISA was developed for the quantitative analysis of aldrin/dieldrin. This has been used to monitor the levels of these pesticides in water samples collected in Egypt. The detection range of the aldrin/dieldrin assay in water was 5–10 ppm without enhancement. River Nile water samples and tap water samples (n = 25) were collected from 25 stations in 16 different governorates in Egypt. Pesticides were detected in 10 of the 25 Nile water samples (40%) at levels from 10 to 110 ppb. In tap water samples, pesticides were not detected at levels greater than the lower limit of the assay. The technique described provides a rapid, economical, highly sensitive and specific method of analysis that is relatively simple to perform and interpret. It will be extremely useful in monitoring levels of pesticides in water used for human consumption.     

Microbial aspects of home enteral nutrition–a discussion

Factors that might contribute to the microbial contamination of enteral feeds prepared and administered in the home are reviewed and the significance of this contamination discussed. Numbers, types and sources of micro-organisms, and possible routes for contamination of home enteral feeds, are outlined and the role of cleaning and disinfection in reducing the microbial load is discussed. Some preliminary guidelines are suggested for the handling of enteral feeds in the home.     

The Results of Water Fluoridation in Ireland

The visit of Dr. Trendley Dean to Dublin in the mid-1950s helped accelerate the decision to introduce water fluoridation as a public health measure in the prevention of caries in the Republic of Ireland. A challenge to the constitutional validity of the Health (Fluoridation of Water Supplies) Act 1960 failed and in 1964 the water supplies of Dublin city were fluoridated. Over the next seven to eight years all the major urban communities in the Republic of Ireland were fluoridated. Currently, 67 percent of the 3.5 million people in the country reside in fluoridated communities. Studies conducted over the last 20 years show that residents of fluoridated communities have better dental health than those in nonfluoridated communities—the mean dmft is lower in children and the number of natural teeth present in adults is higher.     

小鼠经口投镉的慢性毒性研究——病理形态学改变的探讨

选用昆明种小鼠60只,体重18～24克,随机分成三组,每组20只,雌雄各半。通过饮水染毒。一组正常对照,饮自来水,二组饮30ppm含镉水,三组饮300ppm含镉水,染毒时间三个半月。观察指标:体重增长速度、脏器系数、肝肾中镉含量、重点病理形态学改变(光镜和电镜)。结果,30ppm组小鼠肝肾组织有一定病变,300ppm组小鼠的光镜和电镜的病理形态学改变更为明显。提示,小鼠长期摄入镉可引起一定的损害。     

Subclinical pulmonary oedema and intermittent haemodialysis

It has been postulated that patients with chronic renal failure,even in the absence of cardiopulmonary symptoms, accumulateinterstitial pulmonary fluid, which is removed by haemodialysis.To test this hypothesis we used the indocyanine green (ICG)-heavywater double indicator dilution method to measure lung water,cardiac output, and central blood volume in relation to haemodialysis.Ten uraemic patients, without cardiopulmonary symptoms, wereinvestigated at the beginning and end, and 2 h after, a regulardialysis session. A group of 18 surgical patients about to undergoelective abdominal surgery served as controls. Despite normalgas exchange, central blood volume, and cardiac output at thestart of dialysis the mean (SD) lung water was significantlyhigher than in the control group [4.8 (0.9) compared with 3.6(0.7) ml/kg, P<0.001]. There was no correlation between weightgain between sessions of dialysis and the magnitude of lungwater at the start of dialysis. Lung water decreased (P <0.001)to the level of the control group in response to dialysis. Therewas no correlation between weight loss and reduction in lungwater induced by dialysis. In conclusion, we have verified thepresence of subclinical pulmonary oedema which was removed bydialysis in a group of patients with established renal failure.The variations in lung water cannot be explained by hydrostaticmechanisms alone.     

Structure-acute toxicity relationship of aromatic hydrocarbons in mice

The structure-acute toxicity relationship of aromatic hydrocarbons was examined in mice. In all test compounds, the acute toxicity was determined under 2 conditions: control LD₅₀ (LD₅₀-cont) and carbon tetrachloride (CCl₄)-pretreated LD₅₀ (LD₅₀-CCl₄). The CCl₄-pretreatment was done in order to evaluate the toxic potency of compound itself without the influence of metabolism. Both log (1/LD₅₀-cont) and log (1/LD₅₀-CCl₄) were functions of the log P, n-octanol/water partition coefficient, i.e., log (1/LD₅₀-cont) = 0.080 log P − 1.532 and log (1/LD₅₀-CCl₄) = −0.040(log P)² + 0.157 log P − 1.373. Both equations were statistically significant (P < 0.01). The ratio of LD₅₀-cont/LD₅₀-CCl₄ indicated that metabolic activation is more evident in hydrophobic compounds than in hydrophilic compounds. The results suggest that hydrophobicity of the aromatic hydrocarbons plays an important role in determining their acute toxicity.     

影响去离子水质量的主要因素及排除方法

利用电渗析和离子交换柱除去原水中的各种杂质可得到去离子水．而去离子水的质量直接决定了医用注射液的质量。通过近二年的实际操作．列出了与去离子质量有关的主要因素，并提出一些相应见解。     

~(27)AINMR对碱式氯化铝的研究

实验室制得的碱式氯化铝,用~(27)Al NMR进行分析,发现在众多聚合体中存在[AlO_4Al_(12)(OH)_(24)(H_2O)_(12)]~(7+)离子,其化学位移相对于六水合铝离子[Al(H_2O)_6]~(3+)的零位移为δ=63ppm,试铁灵定时比色法对其存在进行了验证。研究了反应条件如酸浓度、铝酸当量比和陈化时间对产物组成及质量的影响,得出最佳条件为盐酸浓度16%,铝酸当量比为1:0.5,陈化时间为50h左右。