Air vs. He-O2 recompression treatment of decompression sickness in guinea pigs

Air vs. He-O2 (20.9% O2) recompression treatment was examined in a model of severe decompression sickness (DCS) using male albino guinea pigs (Cavia porcellus, 500-600 g). Following decompression to the surface from simulated air dives at 200 or 250 fsw, both anesthetized and unanesthetized animals often exhibited responses indicative of a fatal bout of DCS (including hypotension, cardiac arrhythmia, and tachypnea). Upon recompression with air back to depth, good recovery of animals with DCS was observed. Comparison of air vs. He-O2 recompression responses of unanesthetized animals with recompression back to initial depth (200 fsw) revealed a slower recovery from tachypnea with He-O2. Recompression partially back to depth following 200-fsw air dives produced significant differences in the breathing recovery vs. recompression depth relationship between air and He-O2. Treatment effectiveness improved with increasing depth with air, but not with He-O2. These data indicate potential differences in recompression response to air vs. He-O2 when using ventilatory recovery as a measure of effectiveness in treatment of DCS in guinea pigs following air dives.     

Vitamin C deficiency in guinea pigs: variable sensitivity of collagen at different sites.

1. The synthesis of collagen in several tissues, including the C1q component of complement in serum, was measured in vitamin C-deficient and control guinea pigs by incorporating labelled proline into hydroxyproline in vivo. 2. Of the tissues examined, by far the greatest specific effect of vitamin C deficiency was observed in skin. Bone was second in order of sensitivity; skeletal muscle, lung, heart and kidney exhibited only small effects, which were difficult to distinguish from those of inanition, while liver, C1q, and the ethanol-soluble components of serum were virtually insensitive. The effect on urinary hydroxyproline was also extremely small. 3. The lack of sensitivity of C1q confirms previous conclusions (BATES, LEVENE, OLDROYD and LACHMANN 1978), based on total protein bound hydroxyproline levels and total C1 activity in plasma. Since C1q, which turns over rapidly, is insensitive, the high sensitivity of "repair" tissues to vitamin C deficiency is unlikely to be connected with their high turnover rate. Differential concentration of vitamin C by different tissues seems more likely to be the critical factor.     

Sex differences in the coronary heart disease risk profile: a possible role for insulin. The Beaver County Study

The mortality rate from coronary heart disease is much higher among men than women except in diabetes mellitus, which appears to reduce this sex difference. It is hypothesized that the female advantage is due, at least partly, to the more efficient insulin mediated glucose homeostasis in females, an advantage lost in the diabetic state. The authors studied 170 young adult men and women aged 20-24 years from a population-based survey in Beaver County, Pennsylvania, in 1981-1982, in an attempt to further elucidate the sex-specific relationships between fasting serum insulin concentrations and several risk factors. Women who used oral contraceptives and subjects whose fasting serum glucose exceeded 110 mg/dl were excluded. Insulin was related to body mass index in both sexes (r = 0.31; p less than 0.01 for men; r = 0.26, p less than 0.01 for women) and to systolic blood pressure (r = 0.27, p less than 0.01 for men; r = 0.36, p less than 0.001 for women). Insulin was related to diastolic blood pressure in men only (r = 0.31, p less than 0.05). Multivariate analysis revealed fasting serum insulin to be an independent predictor of systolic blood pressure in both sexes and of diastolic blood pressure in men only. Insulin was inversely related to high density lipoprotein cholesterol only among men and this relationship appeared to be largely independent of body mass index and triglycerides. Results indicate that insulin concentration is associated with an adverse coronary heart disease risk factor profile especially among men, consistent with their excess risk of cardiovascular disease.     

Care seeking in Sri Lanka: one possible explanation for low childhood mortality.

This paper examines care-seeking practices of mother caretakers with children less than five years of age in a rural district of Sri Lanka. The study was carried out from June to September 1998, documenting care-seeking practices of mother caretakers in a population of 2248 children in 60 villages. Of the five targeted diseases in the IMCI programme (Integrated Management of Childhood Illnesses) that were the focus of the study, acute respiratory infections (82.0%) and diarrhoea (14.8%) were predominant. Although malnutrition was highly prevalent it was not recognised by mother caretakers as an illness. Findings show that in 65.0% of illness episodes in children the mother caretakers sought outside care and treatment. Caretakers sought treatment from both private and public sectors with the majority seeking care in the private sector. Care seeking of mother caretakers was driven by symptomology. Young children with higher perceived severity and high-risk symptoms were brought to provider care more frequently, although a large percentage of episodes with low-risk symptoms were also brought for outside care. Care seeking was similar across socio-economic groups. The study points out that high care seeking of mother caretakers in Sri Lanka, particularly for illnesses with acute high-risk symptoms and signs, is a plausible explanation for the low level of childhood mortality despite the prevalence of a high rate of malnutrition.     

Health risk factors for the development of decompression sickness among U.S. Navy divers

The relationship between the health status and physical characteristics of 185 U.S. Navy divers and their risk for experiencing decompression sickness was examined utilizing historical cohort design. Data on multiphasic medical examinations performed on these men between 1972-1978 were obtained. Cases of decompression sickness before and after examination were identified. Divers who did experience decompression sickness either before or after examination had significantly higher measures of skinfold thickness and weight when compared to those who remained free of decompression sickness. Those divers in the highest quartile of each of three significant skinfold thicknesses measured had risks for decompression sickness that were generally 9 to 10 times as great as those calculated for the combined lower 3 quartiles and 5 to 6 times as great as the average crude risk calculated for all Navy divers over the past 5 yr. These findings suggest that obesity may be a contributory factor to the occurrence of decompression sickness.     

Multi-trace-element supplementation in enteral formulas for burned guinea pigs.

A burned guinea pig model (30% total-body surface area) was used to study the effects of supplemental trace elements. The animals were fed via gastrostomy with identical formulas (175 kcal.kg-1.day-1, 20% of calories as protein) supplemented with varying amounts of the multi-trace-element preparation MTE-5. Animals in group 1 received no MTE-5, group 2 received 5 ml/L diet, group 3 received 20 ml/L diet, and group 4 received 50 ml/L diet. After 14 days of tube feeding, the animals were killed. Results indicated no significant differences in resting metabolic rate or body weight. However, animals in group 4 were found to have heavier carcass, jejunum gut, and mucosal weights compared with animals in group 1. In a second experiment, all animals received 5 ml of MTE-5/L diet. In each group, however, one of the trace elements (manganese, chromium, selenium, and copper) was elevated to the concentration found in 50 ml of MTE-5. The results shows no significant group differences when only one of the trace elements was elevated in the diet. Together, these results demonstrated that the addition of trace elements to an enteral diet increased carcass and gut mucosal weight in a standard dose-response fashion. All four of the trace elements evaluated were necessary for this response. It is suggested that the addition of larger requirements of trace elements than previously reported may be beneficial after thermal injury.     

Breast cancer risk factors among black women and white women: similarities and differences.

To further explore whether breast cancer risk factors are the same for black women and white women, the authors investigated several biologic, cultural, and social factors in a 1980-1982 case-control study of non-Hispanic black subjects (490 cases, 485 controls) and non-Hispanic white subjects (3,934 cases, 3,901 controls) aged 20-54 years. Logistic regression analyses indicated that blacks and whites shared four risk factors at a comparable magnitude (age at first full-term birth, parity, surgical menopause, and history of benign breast disease). For two observed risk factors, the magnitude (breast feeding) and pattern (family history of breast cancer) of the relation were different in blacks and whites. The relative risks of breast cancer among black women who had first-degree relatives (odds ratio (OR) = 1.61) and second-degree relatives (OR = 1.71) with breast cancer were similar, whereas the relative risk among white women who had first-degree relatives (OR = 2.16) was distinctly larger than for those who had second-degree relatives (OR = 1.44) with breast cancer. The relation of early age at menarche appeared negligible for blacks although significant for whites aged 12 and under (OR = 1.26). The results also indicated that natural menopause, oral contraceptive use, and cigarette smoking may have different, and more complex, relations to breast cancer among blacks and whites.     

Distribution of expired air in carry cots--a possible explanation for some sudden infant deaths.

A possible explanation for the cause of some cot deaths is examined by placing an appropriate cot death model on a cold wet sheet so that its "breath" is directed downwards across the sheet, thereby being cooled and becoming heavy enough to stay trapped in the hollow of the mattress. The breath is then available for rebreathing by the model. The level of carbon dioxide (CO2) "inhaled" is showed to be lower in nostril breathers, singletons and in bassinets and higher with mouth breathing models, in "twins", and in carry cots, especially if the model's head is accidentally covered. Under these conditions a living infant would become progressively acidotic due to inability to adequately excrete its metabolic CO2. This must inevitably be accompanied by increasing hypoxia. If left undisturbed in this predicament, it would rebreathe its own breath for the period of time between feeds and develop increasing degrees of asphyxia, depending on the circumstances outlined.     

Cumulative keyboard strokes: a possible risk factor for carpal tunnel syndrome

ABSTRACT: BACKGROUND: Contradictory reports have been published regarding the association of Carpal Tunnel Syndrome (C.T.S) and the use of computer keyboard. Previous studies did not take into account the cumulative exposure to keyboard strokes among computer workers. The aim of the present study was to investigate the association between cumulative keyboard use (keyboard strokes) and C.T.S. METHODS: Employees (461) of a Governmental data entry & processing unit accepted to participated in a cross-sectional study (response rate: 84.1%). A questionnaire was distributed to the participants with the aim to obtain information on socio-demographics, and risk factors for CTS. The participants were examined for signs and symptoms related to CTS and were asked about previous history or surgery for CTS. The cumulative amount of the keyboard strokes per worker per year was calculated by the use of payroll's registry. Two case definitions for CTS were used. The first included subjects with positive personal history of CTS/surgery for CTS while the second included subjects that belonged to the first case definition plus cases identified through clinical examination. RESULTS: Multivariate analysis indicated-for both case definitions- that those employees with high cumulative exposure to keyboard strokes were at increased risk of CTS (case definition A: OR=2.23;95% CI=1.09-4.52 and case definition B: OR=2. 41; 95%CI=1.36-4.25). A dose response pattern between cumulative exposure to keyboard strokes and CTS has been revealed (p<0.001). CONCLUSIONS: The present study indicated a possible association between cumulative exposure to keyboard strokes and the development of CTS. Cumulative exposure to key-board strokes would be taken into account as an exposure indicator regarding exposure assessment of computer workers. Further research is needed in order to test the results of the current study and assess causality between cumulative keyboard strokes and development of CTS.     

Serum triglyceride: a possible risk factor for ruptured abdominal aortic aneurysm

BACKGROUND: We aimed to determine the relationship between ruptured abdominal aortic aneurysm (AAA) and serum concentrations of lipids and apolipoproteins. METHODS: A cohort of 21 520 men, aged 35-64 years, was recruited from men attending the British United Provident Association (BUPA) clinic in London for a routine medical examination in 1975-1982. Smoking habits, weight, height and blood pressure were recorded at entry. Lipids and apolipoproteins were measured in stored serum samples from the 30 men who subsequently died of ruptured AAA and 150 matched controls. RESULTS: Triglyceride was strongly related to risk of ruptured AAA. In univariate analyses the risk in men on the 90th centile of the distribution relative to the risk in men on the 10th (RO10-90) was 12 (95% confidence interval [CI] : 3.8-37) for triglyceride, 5.5 (95% CI: 1.8-17) for apolipoprotein B (apoB) (the protein component of low density lipoprotein [LDL]), 0.15 (95% CI : 0.04-0.56) for apo A1 (the protein component of high density lipoprotein [HDL]), 3.7 (95% CI: 1.4-9.4) for body mass index and 3.0 (95% CI: 1.1-8.5) for systolic blood pressure. Lipoprotein (a) (Lp(a)) was not a significant risk factor (RO10-90 = 1.6, 95% CI: 0.6-3.0). In multivariate analysis triglyceride retained its strong association. CONCLUSION: Triglyceride appears to be a strong risk factor for ruptured AAA, although further studies are required to clarify this. If this and other associations are cause and effect, then changing the distribution of risk factors in the population (by many people stopping smoking and adopting a lower saturated fat diet and by lowering blood pressure) could achieve an important reduction in mortality from ruptured AAA.     

Racial differences in bladder cancer risk: a case-control study

To determine why the incidence rate of transitional cell bladder cancer in whites in the United States is approximately twice that in blacks, the authors examined data from a large population-based case-control study of bladder cancer conducted in 1978 involving 2,982 cases and 5,782 controls. The relative risk of transitional cell carcinoma for whites compared with blacks was 1.9 before adjustment for the major bladder cancer risk factors, whereas after adjustment for cigarette smoking and occupation it was 1.6 (95% confidence interval (CI): 1.3-2.1). Further adjustment for other risk factors, including history of a bladder infection and a family history of urinary tract cancer, did not alter this estimate. The elevated risk of white compared with blacks was limited, however, to cases whose disease was confined to the mucosa and submucosa. Among cases whose disease had extended to the bladder musculature or beyond, whites were at slightly reduced risk compared with blacks. This suggests that whites may be diagnosed with conditions that go undetected in blacks but that are unlikely as a group to progress to more extensive disease. Because of the population-based nature of the study, it was possible to determine that if bladder cancer incidence among whites of both sexes was reduced to the level among blacks, total incidence in the United States would fall by 36 per cent.     

The performance of different propensity‐score methods for estimating differences in proportions (risk differences or absolute risk reductions) in observational studies

Propensity score methods are increasingly being used to estimate the effects of treatments on health outcomes using observational data. There are four methods for using the propensity score to estimate treatment effects: covariate adjustment using the propensity score, stratification on the propensity score, propensity‐score matching, and inverse probability of treatment weighting (IPTW) using the propensity score. When outcomes are binary, the effect of treatment on the outcome can be described using odds ratios, relative risks, risk differences, or the number needed to treat. Several clinical commentators suggested that risk differences and numbers needed to treat are more meaningful for clinical decision making than are odds ratios or relative risks. However, there is a paucity of information about the relative performance of the different propensity‐score methods for estimating risk differences. We conducted a series of Monte Carlo simulations to examine this issue. We examined bias, variance estimation, coverage of confidence intervals, mean‐squared error (MSE), and type I error rates. A doubly robust version of IPTW had superior performance compared with the other propensity‐score methods. It resulted in unbiased estimation of risk differences, treatment effects with the lowest standard errors, confidence intervals with the correct coverage rates, and correct type I error rates. Stratification, matching on the propensity score, and covariate adjustment using the propensity score resulted in minor to modest bias in estimating risk differences. Estimators based on IPTW had lower MSE compared with other propensity‐score methods. Differences between IPTW and propensity‐score matching may reflect that these two methods estimate the average treatment effect and the average treatment effect for the treated, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Sex differences in risk factors for coronary heart disease: a study in a Brazilian population

Background  

In Brazil coronary heart disease (CHD) constitutes the most important cause of death in both sexes in all the regions of the country and interestingly, the difference between the sexes in the CHD mortality rates is one of the smallest in the world because of high rates among women. Since a question has been raised about whether or how the incidence of several CHD risk factors differs between the sexes in Brazil the prevalence of various risk factors for CHD such as high blood cholesterol, diabetes mellitus, hypertension, obesity, sedentary lifestyle and cigarette smoking was compared between the sexes in a Brazilian population; also the relationships between blood cholesterol and the other risk factors were evaluated.     

Tobacco use: a modifiable risk factor for dental disease among the elderly.

OBJECTIVES. Because the public health literature contains few analytic studies of modifiable behavioral risk factors for dental disease among older community-dwelling populations, the New England Elders Dental Study was undertaken as an epidemiologic study of the oral health status of a representative sample of older adults living within the six New England states. METHODS. Five dentists conducted comprehensive in-home oral health examinations on 1156 community-dwelling adults aged 70 and older to determine whether lifetime use of tobacco products was a significant risk factor for tooth loss, caries, and periodontal disease. RESULTS. Among New England elders, tobacco use was more common among men (18.1%) than women (7.9%), with a combined rate of 12.3%. Further, 64.7% of men and 36.6% of women were previous tobacco users. Years of exposure to tobacco products was a statistically significant risk factor for tooth loss, coronal and root caries, and periodontal disease, regardless of other social and behavioral factors. CONCLUSIONS. Lifelong tobacco use is a modifiable risk factor for poor dental health among older adults. Dental practitioners need to intervene with all their adult patients to discourage use of tobacco products for oral as well as general preventive health care.     

The risk of pregnancy-induced hypertension: black and white differences in a military population.

The relationship between race and risk of pregnancy-induced hypertension was investigated in a cohort of active-duty military women who gave birth during the period 1987 through 1989. Cases were identified through hospital discharge diagnoses and included transient gestational hypertension, pre-eclampsia, eclampsia, and unspecified hypertension complicating pregnancy. Multivariate analysis showed nulliparous Black women to be at a slightly increased risk for all pregnancy-induced hypertension (risk ratio [RR] = 1.2) and for pre-eclampsia (RR = 1.3) compared with nulliparous White women. Black parous women were found to have a slightly reduced risk of all pregnancy-induced hypertension (RR = 0.77) and pre-eclampsia (RR = 0.38) compared with White parous women.     

Culture as an explanation for substance-related problems: a cross-national study among French and Dutch adolescents

Our main goal was to establish whether French and Dutch adolescents differ in rates of substance-related adverse events (e.g. fights, robbery), problems with peers or socializing agents even when controlling for pattern of substance use. For problems with peers and socializing agents due to alcohol we hypothesized that, because of stronger informal control of drinking in France, French adolescents are more likely to report problems with peers and socializing agents. For adverse events due to alcohol no difference was expected after controlling for consumption patterns. For drug-related problems, the hypothesis was that, due to the more restrictive drug policy in France, French adolescents are more likely to report problems with peers, socializing agents and adverse events. Comparable surveys based on samples of adolescent schoolchildren in France (n=9646) and the Netherlands (n=4291) were used. Data were analysed using multilevel logistic regression in which school, age and gender, indicators of substance use and country were used as predictors of substance-related problems. The outcomes show that French adolescents are more likely to report problems with peers and socializing agents due to alcohol even when consumption pattern is controlled for. For adverse events due to alcohol no difference was found between French and Dutch adolescents. For drug-related problems the expected differences were found; i.e. French adolescents are more likely to report problems with peers, socializing agents and adverse events even when controlling for pattern of drug use. It is concluded that there are culturally embedded differences in the rates of some types of problems due to alcohol or drug use. With respect to alcohol use, these differences are most likely due to culturally embedded differences in the informal social control of alcohol use. The differences in rates of drug-related problems are interpreted in the context of national differences in drug policy.     

An explanation for the recent increase in the fall death rate among older Americans: a subgroup analysis

Objective

We sought to explain the recent increase in the death rate from falls among Americans aged 65 years and older.

Methods

Using the CDC WONDER online database, a longitudinal analysis of subgroups of fall mortality based on the International Classification of Diseases, 10th Revision (ICD-10) was conducted in older adults and in younger people. We used linear regression to examine the statistical significance of trends in mortality rates during 1999–2007.

Results

The overall mortality rate from falls increased by 55% among older Americans (≥65 years of age) during 1999–2007, from 29 per 100,000 population to 45 per 100,000 population. For those aged ≥65 years, the largest increase by far (698%) occurred in the subgroup “other falls on the same level,” followed by a moderate increase in falls involving wheelchairs or furniture (48%). The steepest increases at all ages occurred from 1999 to 2000, after ICD-10 took effect. State-level analysis confirmed the findings for the entire United States. From 1999 to 2007, total mortality from falls decreased by 5% in people younger than 45 years of age and increased by 44% for those aged 45–64 years; mortality from “other falls on the same level” increased by 202% and 431%, respectively, in these age groups.

Conclusions

Because the reported minor increases in emergency department and hospitalization rates for falls were insignificant, the almost sevenfold increase in death rates from “other falls on the same level” strongly suggests an effect of improved reporting quality.Falls among older adults are a serious public health problem. Each year, one in three Americans aged 65 years and older falls.^1,2 The annual direct and indirect cost of fall injuries is expected to reach $55 billion (in 2007 U.S. dollars) by 2020.³ A substantial increase in the death rate from unintentional falls has recently been reported among older Americans.^4–9 This increase is perplexing because neither the nonfatal fall rate of 2001–2007 based on Web-based Injury Statistics Query and Reporting System data for patients treated in emergency departments (EDs), nor the fall hospitalization rate of 1997–2005 based on the National Hospital Discharge Survey increased significantly.^9,10 In older people, the rate of ED visits for falls per 100,000 population rose from 4,631 in 2001 to 4,944 in 2007—a 6% increase—compared with a 55% increase in the death rate. This contrasting evidence has raised a critical question: Does the recent increase in fall-related mortality among older Americans reflect an actual increase in fatal falls?There are several possible explanations for the recent increase in deaths coded with a fall as the underlying cause: (1) an increase in fatal injuries from falls; however, the lack of a corresponding increase in ED cases and in hospitalizations negates this possibility;^9,10 (2) an increase in the case fatality rate, which also appears to be equally unlikely given the general improvement in trauma care and treatment of complications in the United States; and (3) a change in reporting the underlying cause of death,⁹ which could have led to the identification of more deaths as having been due to falls.To provide an explanation of the recent increase in fall mortality, we analyzed changes in mortality during 1999–2007 in the many subgroups of falls. Subgroup analysis provided the opportunity to determine whether the increase was associated with certain types of falls. We studied the fall mortality rates of older Americans, as well as younger age groups, at the national and state level.