麦冬类中药组织切片计算机三维重建图鉴

利用计算机技术实现麦冬类中药组织连续切片三维重建与动态显示,为计算机辅助生药学鉴定和教学提供了新的三维图像技术和研究资料。     

Alpha-contingent EEG feedback reduces SPECT rCBF variability.

EEG feedback methods, which link the occurrence of alpha to the presentation of repeated visual stimuli, reduce the relative variability of subsequent, alpha-blocking event durations. The temporal association between electro-cortical field activation and regional cerebral blood flow (rCBF) led us to investigate whether the reduced variability of alpha-blocking durations with feedback is associated with a reduction in rCBF variability. Reduced variability in the rCBF response domain under EEG feedback control might have methodological implications for future brain-imaging studies. Visual stimuli were randomly presented to seven subjects, contingent upon the occurrence of alpha (alpha-contingent stimulation (ACS)) or alpha-blocking (not-alpha-blocking-contingent stimulation (NACS)) events. We employed a within-subjects design. rCBF was measured from multiple, cortical and sub-cortical regions. The primary dependent variables were the Mean, Standard Deviation and the ratio of Mean/Standard Deviation of: 1) the alpha-blocking response durations and 2) the temporally summated rCBF responses within the Visual Associative regions of interest (ROIs). Additional within-subjects rCBF measures were derived to quantify the variance-reducing effects of ACS across multiple, distributed areas of the brain. Both EEG and rCBF measures demonstrated decreased variability under ACS. This improved control was seen for localized as well as anatomically distributed rCBF measures.     

Use of simple clinical signs to predict pneumonia in young Gambian children: the influence of malnutrition.

The current WHO recommendations for the case management of acute respiratory infections (ARI) in children aged 2 months to 5 years in developing countries use fast breathing (respiratory rate of > or = 50 per minute in children under 12 months and > or = 40 in children aged 12 months to 5 years) and lower chest wall indrawing to determine which child is likely to have pneumonia and should therefore receive antibiotics. We have evaluated these and other physical signs in 487 malnourished children and 255 well nourished children who presented with a cough or breathing difficulty. Pneumonia, defined as definite radiological pneumonia or probable radiological pneumonia associated with crackles on auscultation, was present in 145 (30%) of the malnourished children and 68 (26%) of the well nourished children. The respiratory rate predicted pneumonia equally well in the two groups, but to achieve an appropriate sensitivity and specificity the respiratory rate cut-off required in malnourished children was approximately 5 breaths per minute less than that in well nourished children. Intercostal indrawing was more common and lower chest wall indrawing was less common in the malnourished children, with or without pneumonia. These results suggest that fast breathing, as defined at present by WHO, and lower chest wall indrawing are not sufficiently sensistive as predictors of pneumonia in malnourished children. As the latter are a high-risk group, we should like to recommend that children with malnutrition who present with a cough, fast breathing or difficult breathing should be treated with antibiotics.     

In vivo muscarinic cholinergic receptor imaging in human brain with [11C]scopolamine and positron emission tomography.

Cerebral muscarinic cholinergic receptors were imaged and regionally quantified in vivo in humans with the use of [11C]scopolamine and positron emission tomography. Previous studies in experimental animals have suggested the utility of radiolabeled scopolamine for in vivo measurements, on the bases of its maintained pharmacologic specificity following systemic administration and the exclusion of labeled metabolites from the brain. The present studies describe the cerebral distribution kinetics of [11C]scopolamine in normal subjects following intravenous injection. Scopolamine is initially delivered to brain in a perfusion-directed pattern. After 30 to 60 min, activity is lost preferentially from cerebral structures with low muscarinic receptor density including the cerebellum and thalamus. Activity continues to accumulate throughout a 2 h postinjection period in receptor-rich areas including cerebral cortex and the basal ganglia. The late regional concentration of [11C]scopolamine does not, however, accurately parallel known differences in muscarinic receptor numbers in these receptor-rich areas. Tracer kinetic analysis of the data, performed on the basis of a three-compartment model, provides receptor binding estimates in good agreement with prior in vitro measurements. Kinetic analysis confirms significant contributions of ligand delivery and extraction to the late distribution of [11C]scopolamine, reconciling the discrepancy between receptor levels and tracer concentration. Finally, a novel dual-isotope method for rapid chromatographic processing of arterial blood samples in radiotracer studies is presented. The combination of rapid chromatography and compartmental analysis of tracer distribution should have broad utility in future in vivo studies with short-lived radioligands.     

THE IMPACT OF PRE-CLERKING CLINICS ON SURGICAL OPERATION CANCELLATIONS: A PROSPECTIVE AUDIT

Pre-clerking of all patients undergoing elective general surgical operations was introduced at our hospital in an attempt to reduce an unacceptably high operation cancellation rate. A prospective audit has been performed on the effect of this policy on the cancellation rate. Before the introduction of pre-clerking there was a marked seasonal variation in the number of patients who failed to attend for surgery, which could be explained by absence on holiday. This seasonal variation disappeared after the start of pre-clerking clinics, but there has been no reduction in the number of cancellations for medical reasons.     

Regional brain distribution of [18F]GBR 13119, a dopamine uptake inhibitor, in CD-1 and C57BL/6 mice

We have examined the regional brain distribution of [18F]GBR 13119 (18F: beta +, T1/2 = 110 min), a dopamine uptake inhibitor, in CD-1 and C57BL/6 mice. High levels of binding are observed in the striatum of both species, with striatum/cerebellum ratios of 3-4 at 60 min after injection of the radiotracer. Striatum radioactivity and striatum/cerebellum ratios are more than 50% reduced in C57BL/6 mice treated chronically with the neurotoxin MPTP. We conclude mice are an appropriate model for the in vivo study of the dopamine uptake system, and that [18F]GBR 13119 may be a suitable in vivo marker for degeneration of striatal dopaminergic neurons.     

The fate of dienochlor administered orally and dermally to rats

Within four days of receiving a single oral dose (1 mg/kg) of [U-ring-14C]dienochlor [bis(pentachloro-2,4-cyclopentadien-1-yl)] female rats excreted 2 and 88% of the applied 14C in urine and feces, respectively. Metabolites could not be identified and the preponderance of the fecal radioactivity consisted of unextractable 14C-labeled residues. Within 1 day virtually all of the dienochlor had been degraded by rats, with only traces of parent dienochlor in excreta and tissues. After four days only 2% of the applied dose remained in tissues (mainly kidney, liver, and gastrointestinal tract). Pharmacokinetic studies with blood plasma and bile showed dienochlor (and/or its metabolites) to be poorly absorbed. Rats were exposed dermally for 24 hr to [14C]dienochlor formulated as Pentac WP miticide both as an aqueous suspension and as an undiluted wettable powder. Half of the dose adhered to the skin and the other half was found in gauze patches used to protect the treated skin. After a 24-hr exposure over 60% of the radiolabel that adhered to skin was removed by washing with an aqueous soap solution and 86% of this rinsing solution was unmetabolized dienochlor. The dienochlor and its metabolites were transported inefficiently from the application site; only 1% of the applied dose was detected in urine plus feces and less than or equal to 0.2% in tissues. With application rates that simulate field exposure by humans, the actual residue of dienochlor and metabolites in skin (i.e., not removable by washing) is about thirteen times higher following exposure to dienochlor as undiluted wettable powder than as an aqueous suspension.