30例麻疹暴发疫情的调查分析

目的调查本地某乡镇一次麻疹疫情的流行强度,描述其三间分布,分析暴发原因及影响因素。方法现场流行病学调查,酶联免疫捕获法检测麻疹IgM抗体,作免疫空白与麻疹发病关联的病例对照研究。结果2006年5月～7月,该乡镇发生30例麻疹局部暴发,其中29例儿童麻疹,1例成人麻疹,5例麻疹IgM抗体阳性。发病地点主要为小学和和幼儿园,罹患率分别为7.94%、7.87%。免疫空白与发病关系研究表明,初种免疫空白OR=7.2,X2=6.84,复种免疫空白OR=11.0,X2=9.48;影响免疫空白形成的社会因素调查,未接受麻疹疫苗初种或复种儿童的父母双亲常年在外务工占82.4%(28/34),有麻疹疫苗接种史儿童的父母常年在外务工占35.3%(12/34),二者有统计学差异(X2=15.54)。结论免疫空白是麻疹暴发形成的重要因素,农村儿童的父母常年在外务工形成隔代抚养教育对计免工作有负面影响。     

An on-line system for acquisition and processing of cerebral blood flow data

Regional cerebral blood flow is measured by monitoring the clearance from the brain of the gamma emitting radioisotope ¹³³Xe following an intracarotid artery bolus injection. On-line data analysis, which is performed on a PDP $\text{12}\text{30}$ digital computer, involves exponential stripping to isolate grey and white matter flows and integration of the clearance curves to infinity to enable the mean flow to be calculated. The data is displayed in real time and stored on the PDP 12 Linc tapes as a permanent record.     

Stochastic and Coherence Resonance in an In Silico Neural Model

We show that it is possible for chaotic systems to display the main features of stochastic and coherence resonance. In particular, a model of coupled nonlinear oscillators which emulates the transmembrane voltage activities in CA3 neurons, operating in a chaotic regime and in the presence of noise, can exhibit coherence resonance and stochastic resonance. Certain firing frequencies become more "rhythmic" for some optimal values of noise intensity. The effect of noise in different coupling pathways is investigated. We found that the effect of coherence resonance and stochastic resonance are more prominent if noise is presented in either electric field or gap junction coupling pathways. Frequency sensitivity of the model is investigated as a preliminary step in illustrating the principles of possible epileptic seizure control strategies using "chaos control" concepts. Significant effects of stochastic resonance are observed in the 4-8 Hz range. Weaker effects can be found in the 1-4 Hz and 8-10 Hz ranges whereas 0.5 Hz does not exhibit any resonance phenomenon. Our results suggest that: (a) Stochastic resonance could enhance the intrinsic 4-8 Hz rhythms in CA3 neurons more prominently via field coupling pathways. It could also help explain why some reported seizure control strategies using pulse-trains would only be effective at 0.5 Hz. (b) Stochastic resonance-like behavior can occur in the gamma range only if noise is presented via chemical synaptic pathways.     

Functional Thin Polymer Films at High Pressure

Summary: A new thin‐film characterization setup was created based on the combination of a surface plasmon spectrometer with an electrochemical cell operated under high pressure of up to 200 MPa and at temperatures up to 120 °C. The examples given to document its performance include photoisomerization studies with poly(methyl methacrylate) (PMMA) films partly derivatized with disperse red (DR1), as well as, a preliminary account of the electropolymerization of EDOT under pressure and the assessment of the redox properties of the resulting thin PEDOT films.

Sketch of the high‐pressure electrochemistry surface plasmon cell.     

In vitro and ex vivo blood compatibility study of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated hemodialysis hollow fibers

To identify the advantages of 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer-coated polysulfone (PSf) hollow fibers for hemodialyzer and hemofilter minimodules with hollow fibers were made and blood compatibility was evaluated in vitro and ex vivo. Three types of hollow fibers, i.e., pure PSf (no additives), PSf alloyed with poly(1-vinyl-2-pyrrolidone) (PVPy), and PSf coated with the MPC copolymer, were processed in wet conditions. Commercially available hollow fibers (APS) were used as a control sample. The PSf hollow fibers have a condensed structure. A porous structure was observed when the PVPy was alloyed before wet processing, and no effect of the innercoated MPC copolymer on the porous structure was observed. One-tenth-sized minimodules of the conventional hemodialyzer were fabricated with 200 fibers each. The solute permeability of the hollow fibers was evaluated using 10% bovine serum in a buffer solution containing cytochrome C, which is a model protein of ₂-microglobulin. After circulation for 2.5h, the solute permeability of APS and PVPy-alloyed PSf hollow fibers decreased to 50% compared with their initial values. In contrast, the value for the hollow fibers innercoated with the MPC copolymer maintained its initial level. The inner surface of the dialysis membranes was observed with a transmission electron microscope and a layer of adsorbed protein on the PSf, APS, and PVPy-alloyed PSf hollow fibers was observed, but not on the MPC copolymer-coated fibers. Blood cell adhesion was then evaluated by circulation of whole rabbit blood without any anticoagulant ex vivo. Many adherent cells were observed on the PVPy-alloyed PSf hollow fibers; however, blood cells did not adhere or aggregate on the MPC copolymer-coated hollow fibers. From these results, we concluded that the in-situ coating of MPC copolymer on PSf hollow fibers is effective in preventing blood coagulation and maintaining the solute permeability of the fibers.     

An axisymmetric and fully 3D poroelastic model for the evolution of hydrocephalus.

We formulate in general terms the equations for axisymmetric and fully 3D models of a hydrocephalic brain. The model is developed using small strain poroelasticity that includes non-linear permeability. The axisymmetric model is solved for four ventricle shapes, an ellipsoid, a 'peanut' shape, a 'cross' shape and a 'bone' shape. The distribution of fluid pressure, velocity and content in the deformed parenchyma for a blocked aqueduct provides new qualitative insight into hydrocepahlus. Some observations are offered for two forms of cerebrospinal fluid flow abnormality, normal pressure hydrocephalus and idiopathic intracranial hypertension. The model is extended to include a gravitational term in the governing equations and the effect of hydrostatic pressure variation is considered. Results of a fully 3D simulations are described for two horn-like lateral ventricles and one case with two lateral ventricles and a third ventricle.     

Numerical Simulation and Experimental Validation of Blood Flow in Arteries with Structured-Tree Outflow Conditions

Blood flow in the large systemic arteries is modeled using one-dimensional equations derived from the axisymmetric Navier–Stokes equations for flow in compliant and tapering vessels. The arterial tree is truncated after the first few generations of large arteries with the remaining small arteries and arterioles providing outflow boundary conditions for the large arteries. By modeling the small arteries and arterioles as a structured tree, a semi-analytical approach based on a linearized version of the governing equations can be used to derive an expression for the root impedance of the structured tree in the frequency domain. In the time domain, this provides the proper outflow boundary condition. The structured tree is a binary asymmetric tree in which the radii of the daughter vessels are scaled linearly with the radius of the parent vessel. Blood flow and pressure in the large vessels are computed as functions of time and axial distance within each of the arteries. Comparison between the simulations and magnetic resonance measurements in the ascending aorta and nine peripheral locations in one individual shows excellent agreement between the two. © 2000 Biomedical Engineering Society. PAC00: 8719Uv     

The metabolic response to prolonged walking in fed and fasted men

Summary Six healthy men walked 37 km (23 miles) per day over a 3-lap course for each of 4 consecutive days. Subjects were allowed breakfast and an unrestricted diet was consumed after completion of the walk, but no food was consumed during or between laps. At a later date the same subjects walked over the same course after an overnight fast and without breakfast. Completion time for each lap was 139±1 min (mean ±SE) and exercise intensity was equivalent to 17±1% . Mean 24h energy intake was 14.5±0.8 MJ during the fed walk. Estimated daily energy expenditure was 12.0 MJ. Blood glucose concentration fell significantly on the first, third and fourth days of the fed walk, but no subject became hypoglycaemic. Glucose concentration did not fall during the fasted walk and was significantly higher pre-exercise and at the end of laps one and three when compared to the first day of the fed walk. Blood alanine concentration fell significantly after the end of the first lap of each day of the fed walk but not during the fasted walk. Blood lactate levels did not change during the course of either walk. Plasma free fatty acid, glycerol and blood 3-hydroxybutyrate concentrations were unchanged during the passage of the first lap on each day of the fed walk, but all three had increased significantly by the end of the first lap of the fasted walk. The elevations from rest to the end of each day's walking for these three metabolites were of similar magnitude when comparing each day of the fed walk and the fed and fasted walks. The present experiment indicates that feeding a mixed diet can affect the pattern of substrate mobilization in a similar manner to that seen during more strenuous exercise. It also appears that the pattern of fuel substrate mobilization is very similar from one day to the next providing dietary intake is similar.     

Effects of order of presentation of exercise intensities and of sauna baths on perceived exertion during treadmill running

Summary Thirteen male subjects performed a running test on the treadmill consisting of four standard exercise intensities [65%, 75%, 85%, 95% maximal O₂ uptake (VO_2max)] presented in ascending, descending or random order. At the end of each exercise intensity, O₂ consumption, heart rate (f _c), venous blood lactate concentration ([la]_b) and perceived exertion were assessed. This last variable was determined according to the Borg nonlinear CR-20 scale. The same variables were also determined during exercise at a standard intensity (65% or 95%VO_2max) performed before and after a Finnish sauna bath. Ratings of perceived exertion showed a good test-retest reliability (r=0.77); they were the same when the exercise intensity was expressed in relative (%VO_2max) or absolute (speed) terms, and were independent of the order of presentation of the exercise. The latter had no effect onf _c either but it did, however, influence [la]_b, which was significantly higher in the descending, as compared to the ascending or random modes of presentation. The sauna bath increasedf _c at a given exercise intensity, but left perceived exertion and [la]_b unchanged. It was concluded that at least under the present experimental conditions,f _c and venous [la]_b do not play a major role as determinants of perceived exertion.     

Clinical efficacy of reduction in house-dust mite exposure in specially designed, mechanically ventilated "healthy" homes

In temperate climates, energy-conserving measures may increase indoor humidity, enhancing house-dust mite (HDM) growth. Movement of families to "healthy" homes with mechanical ventilation systems reduced HDM exposure. The effect on asthma control of moving to the "healthy" homes was studied in 14 asthmatic patients allergic to HDM. Base-line evaluations of lung function, asthma symptoms, and medication requirements were made before moving and again after 5 and 15 months' residence. A control group of 11 mite-sensitive asthmatic patients who did not move were examined contemporaneously with the study group at base line and at the first follow-up investigation. After 5 months, the residents of the "healthy" homes improved in forced expiratory volume in 1 s (FEV₁), medicine score, and serum IgE. These changes were significantly different from control group measurements. After 15 months, statistically significant improvements from base line were found in FEV₁, average daily peak expiratory flow values, medicine score, symptom score, and serum IgE. Insignificant trends toward improvement were seen in provocation concentration of histamine and blood eosinophils. A significant relation was found between reduction in medicine score and fall in HDM exposure. The present study shows that a specific HDM-avoidance procedure can result in an overall, clinical improvement in HDM-sensitive asthmatic patients.