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101.
Methanol-induced conformational transitions of hen egg white lysozyme were investigated with a combined use of far- and near-UV CD and NMR spectroscopies, ANS binding and small-angle X-ray scattering. Addition of methanol induced no global change in the native conformation itself, but induced a transition from the native state to the denatured state which was highly cooperative, as shown by the coincidence of transition curves monitored by the far- and near-UV CD spectroscopy, by isodichroic points in the far- and near-UV CD spectra and by the concomitant disappearance of individual 1H NMR signals of the native state. The ANS binding experiments could detect no intermediate conformer similar to the molten globule state in the process of the methanol denaturation. However, at high concentration of methanol, e.g., 60% (v/v) methanol/water, a highly helical state (H) was realized. The H state had a helical content much higher than the native state, monitored by far-UV CD spectroscopy, and had no specific tertiary structure, monitored both by near-UV CD and NMR spectroscopy. The radius of gyration in the H state, 24.9 angstroms, was significantly larger than that in the native state (15.7 angstroms). The Kratky plot for the H state did not show a clear peak and was quite similar to that for the urea-denatured state, indicating a complete lack of globularity. Thus we conclude that the H state has a considerably expanded, flexible broken rod-like conformation which is clearly distinguishable from the "molten globule" state. The stability of both N and H states depends on pH and methanol concentration. Thus a phase diagram involving N and H was constructed.  相似文献   
102.
Most instruments used to measure tissue optical properties noninvasively employ data-analysis algorithms that rely on the simplifying assumption that the tissue is semi-infinite and homogeneous. The influence of a layered tissue architecture on the determination of the scattering and absorption coefficients has been investigated in this study. Reflectance as a function of distance from a point source for a two-layered tissue architecture that simulates skin overlying fat was calculated by using a Monte Carlocode. These data were analyzed by using a diffusion theory modelfor a homogeneous semi-infinite medium to calculate the scatter and absorption coefficients. Depending on the algorithm and the radial distance, the estimated tissue optical properties were different from those of either layer, and under some circumstances, physically impossible. In addition, the sensitivity and cross talk of the estimated optical properties to changes in input optical properties were calculated for different layered geometries. For typical optical properties of skin, the sensitivity to changes in optical properties is highly dependent on the layered architecture, the measurement distance, and the fitting algorithm. Furthermore, a change in the input absorption coefficient may result in an apparent change in the measured scatter coefficient, and a change in the in put scatter coefficient may result in an apparent change in the measured absorption coefficient.  相似文献   
103.
Kienle A  Patterson MS  Ott L  Steiner R 《Applied optics》1996,35(19):3404-3412
Laser Doppler measurements were performed on scattering liquids flowing through a highly scattering static medium to determine the scattering coefficient and the anisotropy factor of the liquids. Monte Carlo simulations of light propagation in the static and moving media were used to calculate the Doppler spectra for suspensions of polystyrene spheres in water, and these spectra were in excellent agreement with experimental results. A faster Monte Carlo code was developed so that nonlinear regressions to the measured laser Doppler spectra could be used to determine the anisotropy factor of other liquids. This approach was used to deduce the scattering properties of Intralipid and blood at λ = 820 nm. It was found that the anisotropy factor of blood is well described by Mie theory in contradiction to results reported in the literature that were obtained by goniometric measurement of the phase function.  相似文献   
104.
Much remains to be understood about how low socioeconomic status (SES) increases cardiovascular disease and mortality risk. Data from the Kuopio Ischemic Heart Disease Risk Factor Study (1984-1993) were used to estimate the associations between acute myocardial infarction and income, all-cause mortality, and cardiovascular mortality in a population-based sample of 2,272 Finnish men, with adjustment for 23 biologic, behavioral, psychologic, and social risk factors. Compared with the highest income quintile, those in the bottom quintile had age-adjusted relative hazards of 3.14 (95% confidence interval (CI) 1.77-5.56), 2.66 (95% CI 1.25-5.66), and 4.34 (95% CI 1.95-9.66) for all-cause mortality, cardiovascular mortality, and AMI, respectively. After adjustment for risk factors, the relative hazards for the same comparisons were 1.32 (95% CI 0.70-2.49), 0.70 (95% CI 0.29-1.69), and 2.83 (95% CI 1.14-7.00). In the lowest income quintile, adjustment for risk factors reduced the excess relative risk of all-cause mortality by 85%, that of cardiovascular mortality by 118%, and that of acute myocardial infarction by 45%. These data show how the association between SES and cardiovascular mortality and all-cause mortality is mediated by known risk factor pathways, but full "explanations" for these associations will need to encompass why these biologic, behavioral, psychologic, and social risk factors are differentially distributed by SES.  相似文献   
105.
Proteomics has long been thought to hold the promise of producing results of clinical utility which will influence patient treatment and outcomes. A recent Wellcome Trust/EBI meeting and retreat--“Perspectives in Clinical Proteomics”--brought together experts from a broad range of stakeholder groups with an interest in ensuring proteomics achieves this aim. This viewpoint presents views derived from these forums, proposing a pathway for the development of next-generation proteomic analyses in the clinical setting from selection of candidates through to their validation and ultimate demonstration of utility through health technology assessments. Although not meant to be all encompassing, important elements for proteomics researchers to consider are presented.  相似文献   
106.
ICT in higher education: evaluating outcomes for health education   总被引:1,自引:0,他引:1  
Abstract This paper presents an investigation that examined and compared the effectiveness of collaborative tutorial activities carried out in both web-based and face-to-face learning environments within an undergraduate health education subject. Effectiveness of the different learning environments was measured in terms of observed learning outcomes, analysis of learner interactions and reported perceptions of the learners regarding their experience. Results demonstrated that web-based environments, with embedded collaborative activities, can effectively foster rich learning experiences that result in attaining positive learning outcomes.  相似文献   
107.
OBJECTIVE: We provide a review and analysis of much of the published literature on visual perception issues that impact the design and use of head-mounted displays (HMDs). BACKGROUND: Unlike the previous literature on HMDs, this review draws heavily from the basic vision literature in order to help provide insight for future design solutions for HMDs. METHOD: Included in this review are articles and books found cited in other works as well as articles and books obtained from an Internet search. RESULTS: Issues discussed include the effect of brightness and contrast on depth of field, dark focus, dark vergence, and perceptual constancy; the effect of accommodation-vergence synergy on perceptual constancy, eyestrain, and discomfort; the relationship of field of view to the functioning of different visual pathways and the types of visual-motor tasks mediated by them; the relationship of binocular input to visual suppression; and the importance of head movements, head tracking, and display update lag. CONCLUSION: This paper offers a set of recommendations for the design and use of HMDs. APPLICATION: Consideration of the basic vision literature will provide insight for future design solutions for HMDs.  相似文献   
108.
During the first ten months of 1992 the Oslo Ambulance Department registered 716 incidences of assumed drug-related intoxications. 80% happened in down town Oslo. 19 cases of asystoly were recorded, 13 of the patients recovered after treatment, without sequelae. Five of these patients left the location after emergency help and they refused hospitalization. 432 of the patients were unconscious when the ambulance personal arrived, 472 were treated with naloxone both by the intramuscular and the intravenous route. Most of the persons refused further observation. A team of specially trained out reach workers offers help after acute medical treatment by means of "streetwork". The intervention is directed at addicts who have experienced an overdose.  相似文献   
109.
The polymerase chain reaction was employed to correlate Salmonella serovars isolated from fecal material of greyhounds suffering from gastroenteritis with those isolated from the diet fed to the greyhounds prior to onset of diarrhea. Kennels around the Abilene, Kansas, area were contacted and supplied with materials needed to collect a portion of the diet each day. With the onset of diarrhea, the kennels were instructed to ship the fecal material and diet from the previous 10 days to the laboratory for testing. Forty-one fecal samples and corresponding diets were screened for Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, Staphylococcus intermedius, and pathogenic (piliated) Escherichia coli by direct culture using standard procedures. The fecal material was also screened for coronavirus and parvovirus using electron microscopy. Thirty-five "normal" fecal samples were screened for all of the above mentioned microorganisms as a control. In addition, the fecal material was screened for E. coli verotoxins I and II and clostridial enterotoxins. A total of 61 Salmonella isolates were recovered from the 41 samples of feces and diet submitted for testing; 31 were recovered from the feces and 30 from the diet. Four Salmonella isolates were recovered from the normal fecal samples. Results obtained by PCR, plasmid profiles, antigenic analysis, and antibiogram profiles indicated that 16 of the 31 isolates recovered from the fecal material were the same strain as that recovered from the diet.  相似文献   
110.
Groups of boars and gilts were grown in either single-sex or mixed groups to slaughter weights of 81, 93 or 110 kg liveweight to examine the effects of sex grouping on growth performance, animal behaviour and the development of androstenone-taint in the males. Results confirmed the well known growth advantages of entire males and showed that no husbandry problems of any significance were incurred with the boars and gilts raised together, particularly in those groups slaughtered before reaching 100 kg liveweight. In pigs taken to heavier weights, boars were successfully reared with gilts without incurring management problems, although growth performance was slightly poorer for the boar/gilt groups compared with mixed castrates and gilts, and some of the boars had high concentrations of androstenone in the fat. Thus, for pigs intended for slaughter at heavy commercial weight, the evidence suggests that split-sex rearing (and therefore feeding) should be practised. No useful correlations of androstenone concentration in fat were found with thickness of backfat, age, carcass weight or liveweight at slaughter.  相似文献   
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