Use of shadows to retrieve water vapor in hazy atmospheres.

Techniques aimed at retrieving water vapor from satellite data of reflected near-infrared solar radiation have progressed significantly in recent years. These techniques rely on observation of water vapor attenuation of near-infrared solar radiation reflected by the Earth's surface. Ratios of measured radiances at wavelengths inside and outside water vapor absorbing channels are used for retrieval purposes. These ratios partially remove the dependence of surface reflectance on wavelength and are used to retrieve the total column water vapor amount. Hazy atmospheric conditions, however, introduce errors into this widely used technique. A new method based on radiance differences between clear and nearby shadowed surfaces, combined with ratios between water vapor absorbing and window regions, is presented that improves water vapor retrievals under hazy atmospheric conditions. Radiative transfer simulations are used to demonstrate the advantage offered by this technique.

Changes in the use of hormone replacement therapy in New Zealand from 1991-1997.

AIMS: To describe changes in the prevalence of hormone replacement therapy (HRT) use in New Zealand women aged 45-64 years from 1991-1997. METHODS: For each of two population-based surveys, 2,000 women aged 45-64 years were randomly selected from the electoral roll and sent questionnaires. The response rates were 78% in 1991 and 73% in 1997. RESULTS: Current use of HRT increased from 12% in 1991 to 20% in 1997 (OR=2.0, 95% CI (1.6, 2.4)). In both surveys, professional women or those with husbands in professional occupations were more likely to use HRT. Women in all socio-economic and educational groups experienced a two fold increase in the use of HRT from 1991 to 1997. The majority started HRT primarily or partly for relief of symptoms (85% in 1991, 83% in 1997). While almost half had started it to prevent osteoporosis in both surveys, there was a marked increase between 1991 and 1997 in the proportion of women who had started it to prevent coronary heart disease (13% in 1991, 25% in 1997, p=0.0002). In each survey, just over a quarter of women had undergone a hysterectomy and they were 2-3 times more likely to be using HRT than other women. CONCLUSIONS: In New Zealand the prevalence of HRT use has doubled in the 1990s, despite uncertainties about the magnitude of benefits and risks of its long-term use.

Long-term assessment of psychological well-being in a randomized placebo-controlled trial of cholesterol reduction with pravastatin. The LIPID Study Investigators.

BACKGROUND: There is controversial evidence that a low serum cholesterol level is associated with an increased risk of depression, suicide, and violence. The aim of this study was to identify or exclude any small or infrequent adverse effect of long-term reduction of serum cholesterol with pravastatin sodium on psychological well-being. METHODS: The study population consisted of 1130 respondents from a representative sample of 1222 patients with stable coronary artery disease participating in the Long-term Intervention with Pravastatin in Ischaemic Disease (LIPID) study. Subjects were randomized in a double-blind manner to treatment with pravastatin sodium, 40 mg/d (n = 559), or placebo (n = 571) for at least 4 years. Psychological well-being was assessed with a standard self-administered questionnaire at baseline and after 6 months, 1 year, 2 years, and 4 years. The questionnaire assessed anxiety and depression, anger, impulsiveness, alcohol consumption, and adverse life events. RESULTS: Serum cholesterol levels decreased by an average of 1.3 mmol/L (50 mg/dL) with pravastatin therapy and did not change with placebo. During follow-up there was no significant difference by treatment group in measures of anxiety and depression, anger expression, or impulsiveness (95% confidence interval excluded differences of >0.2 SD) and no difference in the proportion of subjects with excessive alcohol consumption or adverse life events (odds ratio, 1.0; 95% confidence interval, 0.8-1.2). There was no evidence of a treatment effect for persons whose baseline serum cholesterol level was in the lowest 10% (<4.6 mmol/L [178 mg/dL]) or whose scores for anxiety and depression, anger, or impulsiveness were in the highest 10% at baseline. There was no association between change in the serum cholesterol level and measures of anxiety and depression, anger, or impulsiveness during follow-up. CONCLUSION: Long-term reduction of serum cholesterol with pravastatin has no adverse effect on psychological well-being.

A randomised controlled trial of dietary energy restriction in the management of obese women with gestational diabetes.

A randomised controlled trial was designed to determine the effect of moderate 30% maternal dietary energy restriction on the requirement for maternal insulin therapy and the incidence of macrosomia in gestational diabetes. Although the control group restricted their intake to a level similar to that of the intervention group (6,845 kiloJoules (kJ) versus 6,579 kJ), the resulting cohort could not identify any adverse effect of energy restriction in pregnancy. Energy restriction did not alter the frequency of insulin therapy (17.5% in the intervention group and 16.9% in the control group). Mean birthweight (3,461 g in the intervention group and 3,267 g in the control group) was not affected. There was a trend in the intervention group towards later gestational age at commencement of insulin therapy (33 weeks versus 31 weeks) and lower maximum daily insulin dose (23 units versus 60 units) which did not reach statistical significance. Energy restriction did not cause an increase in ketonemia.

Socioeconomic and sex differentials in reason for sickness absence from the Whitehall II Study.

OBJECTIVES: Large socioeconomic differences exist in disease and mortality. This paper describes the distribution of specific medical reasons for sickness absence by grade of employment in the Whitehall II study and validates the medical reason by comparison with general practitioners' records. METHODS: Analysis of sickness absence data on 5620 male and female civil servants aged 35-55 years. Data have been collected from 12 of the 20 London based civil service departments participating in the Whitehall II study, where medical reason for absence was available. Rates and distributions of reasons for absence for short spells (< or = 7 days) and long spells (> 7 days) were analysed. RESULTS: Respiratory disorders and gastroenteritis accounted for over half of all spells of absence, with headache and migraine, musculoskeletal disorders, injury, and neurosis accounting for a further 20%-30% of absences. There was an inverse association with employment grade, the lower the grade the higher the rate of absence for both short spells (< or = 7 days) and long spells (> 7 days). In general, women had higher rates of absence than men. Comparison of reason for very long spells of absence (> 21 days) showed moderate agreement between civil service and general practitioner. CONCLUSION: There is a lack of national comprehensive data on sickness absence and medical reason for absence, in particular for women and for spells of different duration. Data from the Whitehall II study show large employment grade and sex differences in the distribution of medical reasons for absence that are similar to socioeconomic differences in morbidity documented in other studies. Possible explanations include the subjective nature of illness and disease; the work/family interface; and the influence of the absence culture. Longer term follow up will provide information on whether sickness absence relates to serious morbidity and mortality.

Sterility of anesthetic and resuscitative drug syringes used in the obstetric operating room.

UNLABELLED: Because of the constant threat of emergent cesarean delivery, anesthetic induction and resuscitation drugs are often drawn into syringes and stored in the obstetric operating room (OR). This study investigated the potential for bacterial and fungal contamination of six drugs (thiopental, succinylcholine, ephedrine, atropine, lidocaine, and oxytocin) often prepared in the obstetric OR. A total of 756 drug syringes were prepared and stored in the obstetric OR for 8 days using normal clinical practices. Starting on Day 0, and subsequently on Days 4 and 8 of the experiment, 42 syringes of each drug were randomly selected from the pool, filtered through a 0.45-microm porosity sterile cellulose filter, and cultured on 5% sheep blood agar. Of the 756 syringes tested, none grew organisms of any type, which indicates a probability of drug sterility of > or = 0.9961 (95% confidence interval [CI]). The data from the cultures performed on syringes on Day 0 indicate a probability of initial contamination of < or = 0.018 (95% CI). This study demonstrates a high probability of sterility in drugs drawn into sterile syringes and stored at room temperature in an OR environment for up to 8 days. IMPLICATIONS: Drug syringes stored in emergency operating rooms are discarded after 24 h because of possible contamination. We searched for microorganisms in drug syringes stored in the operating room for up to 8 days. No microbes were detected using standard sterility testing techniques. Adopting longer storage periods could result in significant cost savings.

Psychosocial work environment and sickness absence among British civil servants: the Whitehall II study.

OBJECTIVES: This study sought to examine the association between the psychosocial work environment and subsequent rates of sickness absence. METHODS: The analyses were based on a cohort of male and female British civil servants (n=9072). Rates of short spells (7 days) of sickness absence were calculated for different aspects of the psychosocial work environment, as measured by self-reports and personnel managers' ratings (external assessments). RESULTS: Low levels of work demands, control, and support were associated with higher rates of short and long spells of absence in men and, to a lesser extent, in women. The differences were similar for the self-reports and external assessments. After adjustment for grade of employment, the differences were diminished but generally remained significant for short spells. The combination of high demands and low control was only associated with higher rates of short spells in the lower grades. CONCLUSIONS: The psychosocial work environment predicts rates of sickness absence. Increased levels of control and support at work could have beneficial effects in terms of both improving the health and well-being of employees and increasing productivity.

Sickness absence as a measure of health status and functioning: from the UK Whitehall II study.

STUDY OBJECTIVE: To investigate the relationship between self reported health status and sickness absence. DESIGN: Analysis of questionnaire and sickness absence data from the first phase of the Whitehall II study--a longitudinal study set up to investigate the degree and causes of the social gradient in morbidity and mortality. SETTING: London offices of 20 civil service departments. PARTICIPANTS: Altogether 6895 male and 3413 female civil servants aged 35-55 years. Analysis was conducted on 88% of participants who had complete data for the present analysis. MAIN RESULTS: A strong inverse relation between the grade of employment (measure of socioeconomic status) and sickness absence was observed. Men in the lowest grade had rates of sickness absence six times higher than those in the highest grade. For women the corresponding differences were two to five times higher. In general, the longer the duration of absence, the more strongly did baseline health predict rates of absence. However, the health measures also predicted shorter spells, although to a lesser extent. Job satisfaction was strongly related to sickness absence with higher rates in those who reported low job satisfaction. After adjusting for health status the association remained for one to two day absences, but was greatly reduced for absences longer than three days. CONCLUSION: There was a strong association between ill health and sickness absence, particularly for longer spells. The magnitude of the association may have been underestimated because of the strength of the association between grade of employment and sickness absence. It is proposed that sickness absence be used as an integrated measure of physical, psychological, and social functioning in studies of working populations.

Work characteristics and psychiatric disorder in civil servants in London.

STUDY OBJECTIVE: To describe the association between self reported and externally assessed work characteristics and psychiatric disorder. DESIGN: Analysis of questionnaire data collected from the first phase of the Whitehall II study, a cohort study of an employed population. SETTING: Twenty civil service departments in London. PARTICIPANTS: Altogether 6900 male and 3414 female civil servants aged 35-55 years. MAIN RESULTS: High levels of subjective social support at work, control at work, job variety, and skill use were associated with greater satisfaction and wellbeing and less psychiatric disorder measured by the 30 item general health questionnaire (GHQ). High levels of subjective work pace and conflicting demands were associated with less satisfaction and wellbeing and greater psychiatric disorder. The combined effects of work characteristics were similar to the effects of the work characteristics considered separately, except that for men there was a small interaction between psychological demands and control on the GHQ. There was little overall support for the two factor job strain model. In contrast, objective indices of work were generally not associated with the psychological indices. Findings in men and women were generally comparable and were not significantly influenced by employment grade. CONCLUSIONS: Negative affectivity and a tendency to report negatively about both work and the psychological indices may partly explain the difference in the findings between subjective and objective work characteristics. However, subjective work characteristics were still associated with psychiatric disorder after adjusting for negative affectivity. The potential confounding effects of employment grade did not explain the association between either subjective or objective work characteristics and the psychological indices. While modifications to the work environment may directly reduce certain adverse physical health effects, the influence of work place design and management on psychological wellbeing, satisfaction, and psychiatric disorder may be mediated through subjective perceptions of the work environment.

Sickness absence for psychiatric illness: the Whitehall II Study.

Over the past 20 years, rates of sickness absence have increased and psychiatric disorders have become an important cause of sickness absence. The socio-demographic associations for psychiatric sickness absence are reported from the Whitehall II study, a longitudinal survey of 10,308 London-based male and female civil servants between 35-55 years. Short spells (< or = 7 days), long spells (> 7 days) and very long spells (> 21 days) of sickness absence were examined in 5620 civil servants for whom reason for absence was available in civil service records. Civil service coding of reasons for absence was validated against report of general practitioners' diagnoses. Psychiatric disorder, largely neurosis and neurosis ill-defined, was the third most common cause of long spells of sickness absence in women and the fourth most common in men. For both men and women it was the second most common cause of very long spells of absence. Psychiatric sickness absence for short, long and very long spells was more frequent in lower employment grades than higher employment grades in keeping with the pattern for other illnesses. This partly explains the higher rate of sickness absence in women than men. Widowed and single men, and divorced women had high rates of psychiatric sickness absence. Comparing reason codes based on sickness certificates with general practitioners reports, there appeared to be evidence of under-reporting of psychosis on certificates.(ABSTRACT TRUNCATED AT 250 WORDS)

Flexible sigmoidoscopy or colonoscopy for colorectal screening: a randomized trial of performance and acceptability.

In a randomized clinical trail to assess acceptability, yields, costs, and unwanted effects of screening procedures, 232 subjects (137 with family history of colorectal carcinoma or adenoma, 95 without) were offered either flexible sigmoidoscopy or colonoscopy. Subjects with polyps found on sigmoidoscopy were followed up by colonoscopy. The two procedures were similar in compliance (65%) and yield (19% adenoma, 15% hyperplastic polyps). Polyps of either type were more common in those with a family history (prevalence: 41% compared with 24% without family history, p = 0.04). Costs per procedure were 60% lower for sigmoidoscopy, but follow-up colonoscopy reduced this cost advantage to 20% per subject. The subjects found the preparation for sigmoidoscopy easier, but the procedure more uncomfortable and embarrassing, as colonoscopy was performed under sedation. In this hospital-based study, colonoscopy was as acceptable to subjects, and only slightly more costly than sigmoidoscopy. Advantages of sigmoidoscopy would be greater for use outside hospitals and with less intensive follow up.

Alcohol consumption and sickness absence: from the Whitehall II study.

Previous studies suggest that problem drinkers have markedly increased sickness absence. However, it is not clear how more moderate alcohol consumption and abstinence relate to sickness absence. As part of the Whitehall II study the relationship between different drinking patterns and sickness absence is examined. A total of 10,314 male and female civil servants completed a baseline questionnaire about their drinking habits--the amount of alcohol consumed over the past 7 days and the frequency of drinking over the past 12 months. All sickness absence has been recorded prospectively. Drinking patterns and sickness absence are examined for short spells (< or = 7 days) and long spells (> 7 days) adjusting for other causes of sickness absence: age, grade of employment, smoking, work characteristics and baseline health. Alcohol consumption was strongly related to employment grade, the lower the grade the higher proportion of men and women reporting no alcohol consumption. For men the relation of alcohol intake to short spells of sickness absence (< or = 7 days) appeared to be U-shaped, for long spells (> 7 days) increased rates of absence were found only in frequent drinkers. There was no clear relationship for women, however higher rates of sickness absence were found in non-drinkers.

Explaining socioeconomic differences in sickness absence: the Whitehall II Study.

OBJECTIVE: To describe and explain the socioeconomic gradient in sickness absence. DESIGN: Analysis of questionnaire and sickness absence data collected from the first phase of the Whitehall II study. Grade of employment was used as a measure of socioeconomic status. SETTING: 20 civil service departments in London. SUBJECTS: 6900 male and 3414 female civil servants aged 35-55 years. MAIN OUTCOME MEASURES: Rates of short spells (< or = 7 days) and long spells (> 7 days) of sickness absence. RESULTS: A strong inverse relation between grade of employment and sickness absence was evident. Men in the lowest grade had rates of short and long spells of absence 6.1 (95% confidence interval 5.3 to 6.9) and 6.1 (4.8 to 7.9) times higher than those in the highest grade. For women the corresponding rate ratios were 3.0 (2.3 to 3.9) and 4.2 (2.5 to 6.8) respectively. Several risk factors were identified, including health related behaviours (smoking and frequent alcohol consumption), work characteristics (low levels of control, variety and use of skills, work pace, and support at work), low levels of job satisfaction, and adverse social circumstances outside work (financial difficulties and negative support). These risk factors accounted for about one third of the grade differences in sickness absence. CONCLUSION: Large grade differences in sickness absence parallel socioeconomic differences in morbidity and mortality found in other studies. Identified risk factors accounted for a small proportion of the grade differences in sickness absence. More accurate measurement of the risk factors may explain some of the remaining differences in sickness absence but other factors, as yet unrecognised, are likely to be important.

Health inequalities among British civil servants: the Whitehall II study.

The Whitehall study of British civil servants begun in 1967, showed a steep inverse association between social class, as assessed by grade of employment, and mortality from a wide range of diseases. Between 1985 and 1988 we investigated the degree and causes of the social gradient in morbidity in a new cohort of 10,314 civil servants (6900 men, 3414 women) aged 35-55 (the Whitehall II study). Participants were asked to answer a self-administered questionnaire and attend a screening examination. In the 20 years separating the two studies there has been no diminution in social class difference in morbidity: we found an inverse association between employment grade and prevalence of angina, electrocardiogram evidence of ischaemia, and symptoms of chronic bronchitis. Self-perceived health status and symptoms were worse in subjects in lower status jobs. There were clear employment-grade differences in health-risk behaviours including smoking, diet, and exercise, in economic circumstances, in possible effects of early-life environment as reflected by height, in social circumstances at work (eg, monotonous work characterised by low control and low satisfaction), and in social supports. Healthy behaviours should be encouraged across the whole of society; more attention should be paid to the social environments, job design, and the consequences of income inequality.

Comparison of cutaneous and in vitro histamine release by muscle relaxants.

The authors compared histamine release in vitro in a human neonatal foreskin preparation to histamine release in vivo in adult humans with three commonly used muscle relaxants (vecuronium, atracurium, and d-tubocurarine) in concentrations ranging from 10(-1) M to 3 X 10(-3) M. They measured histamine release directly in the in vitro preparation and measured the wheal size resulting from intradermal injection in vivo. Both in vivo and in vitro testing revealed dose-related histamine release with d-tubocurarine and atracurium (P less than .05). Vecuronium did not release histamine at any concentration. It was concluded that the infant foreskin model is a valid predictor of histamine release by muscle relaxants in vivo, and can provide valuable information about mechanisms of histamine release by these, and perhaps others, drugs used in anesthetic practice.