Antioxidant supplementation and respiratory functions among workers exposed to high levels of ozone

Ozone exposure has been related to adverse respiratory effects, in particular to lung function decrements. Antioxidant vitamins are free-radical scavengers and could have a protective effect against photo-oxidant exposure. To evaluate whether acute effects of ozone on lung functions could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blind crossover design. Street workers (n = 47) of Mexico City were randomly assigned to take daily a supplement (75 mg vitamin E, 650 mg vitamin C, 15 mg beta carotene) or a placebo and were followed from March to August 1996. Pulmonary function tests were done twice a week at the end of the workday. During the follow-up, the mean 1-h maximum ozone level was 123 ppb (SD = 40). During the first phase, ozone levels were inversely associated with FVC (beta = -1.60 ml/ppb), FEV1 (beta = -2.11 ml/ppb), and FEF25-75 (beta = -4.92 ml/ppb) (p < 0.05) in the placebo group but not in the supplement group. The difference between the two groups was significant for FVC, FEV1, and FEF25-75 (p < 0.01). During the second phase, similar results were observed, but the lung function decrements in the placebo group were smaller, suggesting that the supplementation may have had a residual protective effect on the lung. These results need to be confirmed in larger supplementation studies.     

Emergency hospital admissions for respiratory disorders attributable to summer time ozone episodes in Great Britain

BACKGROUND: There is accumulating evidence from various countries, including the UK, that ground level ozone concentrations are associated with increased daily hospital admissions for respiratory diseases. This paper estimates the impact of ozone episodes on daily hospital admissions for respiratory disease in Great Britain by combining locally based exposure-response relationships with mapped estimates of ozone exposure for the population in the summers of 1993 and 1995. METHODS: For the given years the available ozone measurements were used to construct maps of ozone concentrations for each day. The population exposed to a given concentration of ozone on a particular day was calculated from census data using a geographical information system. The additional hospital admissions for respiratory disease were then estimated using a regression coefficient for London. RESULTS: It is estimated that 0.10% (a total of 184) and 0.35% (a total of 643) of hospital admissions for respiratory disorders during the summers of 1993 and 1995, respectively, can be attributed to levels of ozone above 50 ppb (the recommended air quality standard for the UK). A sensitivity analysis for 1995 found that, if no threshold is assumed, the estimate is increased by about twenty fold (6% of admissions attributable). CONCLUSIONS: The additional hospital admissions for respiratory disease attributable to ozone are very small in both absolute and relative terms if a threshold of 50 ppb is assumed, but this estimate is very sensitive to threshold assumptions.     

Lung function and prevalence of irritation of eyes and respiratory airways on days with elevated ozone concentrations

Interactions between HPA (Hypothalamic-pituitary-axis) and immune system seem to involve the EPO (endogenous opioid peptides) system, as shown by some recent findings. Possible relationships between beta-endorphin (beta-End) synthesis and severity rate of immunodeficiency have been studied in 48 HIV Ab positive patients, at different stages of infection. A statistically significant decrease in the beta-End synthesis was observed in these patients, as compared to a control group of 19 healthy subjects, but this decrease was not related to the CD4+T lymphocytes number. Plasmatic levels modifications of HPA-related peptides were not observed in the IVC1 CDC group.     

Effects of intermittent ozone exposure on peak expiratory flow and respiratory symptoms among asthmatic children in Mexico City

PURPOSE: The purpose of this research was to study adolescents' perceptions of violence in their communities and schools and examine the relationship between these reports and their emotional and behavioral functioning, controlling for the effects of family violence and other sociodemographic variables. METHODS: Respondents included 935 urban and suburban high school students who completed the Youth Self-Report (YSR) as well as measures assessing their perceptions of community, school, and family violence. RESULTS: This sample of high school students was exposed to high levels of violence in their communities and schools. Over 45% of the students reported witnessing severe forms of violence such as a shooting or stabbing in their communities or schools during the year prior to the study. Hierarchic regression analyses revealed that for males, exposure to community and school violence was a significant predictor of aggressive acting-out behaviors, even when controlling for the effects of family violence and other sociodemographic variables. For girls, only exposure to school violence was a significant predictor of aggression. The results for internalizing scores (depression, withdrawal) were less impressive, particularly for males. CONCLUSIONS: The high levels of violence exposure of adolescents in their communities and schools and the associated increase in behavior problems suggest the need for developing school and community intervention programs to treat violence and its impact.     

新型智能测铁仪的研制

系统介绍了一种新型测定Fe(和Fe(的智能仪器,其检测原理是传统的分光光度分析。仪器通过MSP430单片机系统将整个分析过程智能化、自动化。从采样、注样、数据采集和处理、输出显示均自动完成。整台仪器外观优美,简单易用。     

Particle size determination of a flocculated suspension using a light-scattering particle size analyzer

Microscopy is a useful and direct method for measuring the particle size of a suspension because, in addition to the particle size and size distribution, it provides visual detection of the shape and state of aggregation of the particles in the suspension. However, this method suffers from the shortcomings of being tedious and time consuming. In this study, a light-scattering particle size analyzer was used to determine the particle size and size distribution of a flocculated suspension. The sonication of the sample prior to and during measurement was found to be critical in ensuring that data are representative of the size distribution of the primary particles of the suspension. The light-scattering results were further confirmed by data generated using a polarized light microscope equipped with an image analyzer.     

Improvement of a d-norgestrel-releasing IUD

A d-norgestrel-releasing IUD was introduced into the uterine cavity of 18 healthy women. The carrier material for d-norgestrel was silastic attached to the vertical arm of a Nova-T. 2 kinds of d-norgestrel IUDs were used, with d-norgestrel-releasing surface areas of 83 sq mm and 132 sq mm, respectively. The determination of plasma concentrations of estradiol and progesterone showed that ovulation occurred in 8 of 12 subjects thus assayed. Endometrial biopsies showed uniform suppression. The bleeding pattern was carefully registered and found to be fairly regular and significantly reduced in amount. d-Norgestrel concentrations ranged between .1-.2 ng/ml. During a total of 60 woman-months the pregnancy rate was zero.     

A new type of oxygen analyzer utilizing a potentiostatic coulometric titration technique

A new type of oxygen analyzer was constructed utilizing the electrochemical oxygen pump: Pt, air/ZrO₂ (+ CaO)/Ar + H₂ + H₂0 gas mixture, Pt. Copper, indium, or tin samples were melted in a circulating Ar + H₂ gas mixture; the oxygen content was then determined within 3 minutes from the change in the electrical current passing through the oxygen pump. The analytical values were highly consistent and reliable despite the fairly low oxygen concentrations in the samples. Neither standard samples nor the establishment of blank conditions was necessary. This type of oxygen analyzer appears to be useful for determining oxygen concentrations less than 1 wt ppm.     

Error in the determination of the particle-size distribution of a powder with a laser analyzer

Conclusions Simple expressions have been obtained from known parameters of a flow-type chamber for estimating errors in laser analyzer measurements of the main numerical particle size distribution characteristics of powders obeying the logarithmic normal law. It is shown that, in spite of marked errors (Fig. 1) in size measurements on single particles whose trajectories are deflected from the laser beam center, it is possible to attain high accuracy in the measurement of numerical particle distribution characteristics by suitable choice of aero or hydrodynamic particle stream focusing [5] (Table 1: maximum error in the determination of the amount of the main fraction in a powder of particle size 3/2 _f = 1.9% at 2_j = 15 and _f = 4.3% at 2_j = 72 m). Without good particle stream focusing, measurements may be very inaccurate (Table 1: _f = 24% at 2_j = 120 m and _f = 55.5% at 2_j = 170 m). The accuracy of laser analyzer measurements grows with increasing curvature (coefficient n) of analyzer calibration characteristics and vice versa. The q/qt relationships obtained may find application in the assessment of errors in particle size analyses of powders with particle distributions differing from the logarithmic normal law.Translated from Poroshkovaya Metallurgiya, No. 12(288), pp. 15–20, December, 1986.     

臭氧对煤粉燃烧的影响

根据强紫外线辐射空气可产生臭氧的原理,将经紫外辐射后的空气通入热天平与煤粉发生燃烧反应,采用热分析方法研究臭氧对煤粉燃烧的影响.实验表明紫外辐射空气得到的少量臭氧使煤粉燃烧的失重和放热时间提前.对煤粉燃烧的动力学进行分析,结果显示臭氧使煤粉燃烧反应的活化能降低.紫外线激发高温氧气产生氧原子的热力学计算结果表明:温度越高,氧分子越容易被紫外线激发为氧原子.提出了使用强紫外线辐射热风促进高炉喷煤燃烧的设想.     

Resolving capacity of the human auditory analyzer

Resolution of human auditory analyser to tine-impulse signals in the noise has been studied AX method was put in the basis of the experiment. Signals were the sinusoid intercepts. Relationships between probability of erroneous distinguishing of the signals and untuning, signal/noise and number of periods in the frequency range from 150 to 4800 Hz. It has been shown that the accepting auditory properties are invariants to the time transformations, the wave number of the sinusoid being the determining characteristics of the stimulus. A concept of frequency--time band of the auditory system is introduced. Its width according to the experimental data depends on the signal/noise ratio.     

Absolute CD4 counts obtained by a three-color flow-cytometric method without the use of a hematology analyzer

We evaluated the Ortho TRIO-Cytoronabsolute system for determining absolute CD4 counts. The CD4 counts in our blood specimens from 100 individuals ranged from 3 to 1,962; the percent CD4 ranged from 1.3 to 62.2, respectively. The TRIO system was biased toward lower absolute counts than a combination of flow cytometry and hematology but showed no bias in percent CD4 calculations.