Analysing how changes in the health status of healthcare workers affects epidemic outcomes.

During a disease outbreak, healthcare workers (HCWs) are essential to treat infected individuals. However, these HCWs are themselves susceptible to contracting the disease. As more HCWs get infected, fewer are available to provide care for others, and the overall quality of care available to infected individuals declines. This depletion of HCWs may contribute to the epidemic's severity. To examine this issue, we explicitly model declining quality of care in four differential equation-based susceptible, infected and recovered-type models with vaccination. We assume that vaccination, recovery and survival rates are affected by quality of care delivered. We show that explicitly modelling HCWs and accounting for declining quality of care significantly alters model-predicted disease outcomes, specifically case counts and mortality. Models neglecting the decline of quality of care resulting from infection of HCWs may significantly under-estimate cases and mortality. These models may be useful to inform health policy that may differ for HCWs and the general population. Models accounting for declining quality of care may therefore improve the management interventions considered to mitigate the effects of a future outbreak.

Can dual energy X-ray absorptiometry provide a valid assessment of changes in thigh muscle mass with strength training in older adults?

OBJECTIVE: To determine how dual-energy X-ray absorptiometry (DXA) compares to computed tomography (CT) for measuring changes in total thigh skeletal muscle (SM) mass with strength training (ST) in older adults. SUBJECTS: Fifty previously sedentary, relatively healthy older men (n=23, 60 (s.d.=7.5) years) and women (n=27, 60 (s.d.=9.3) years). RESULTS: Results indicate that there was a significant increase in thigh SM mass with ST measured by both CT (3.9+/-0.4%) and DXA (2.9+/-0.6%) methods (both P<0.001), and there was not a significant difference in percent change between the two methods, although there was a substantial absolute difference ( approximately 2 kg) at baseline between the two methods. Although Bland-Altman plots indicate overall agreement between the percent thigh SM mass changes of DXA vs CT methods, the 3.4% error associated with DXA was greater than the thigh SM mass change from DXA. However, the CT measured change in thigh SM mass was greater than its error (0.6%). CONCLUSIONS: DXA overestimates baseline and after ST thigh SM mass, and may not be able to detect small changes in thigh SM mass with ST due to its higher error. Although DXA has certain advantages that warrant is used in epidemiologic and intervention studies, improvements to DXA are needed for the accurate assessment of small changes in thigh SM mass.

Mild hypoxic ischaemic encephalopathy and long term neurodevelopmental outcome - A systematic review.

AIMS: Hypoxic ischaemic encephalopathy (HIE) remains a significant cause of long term neurodisability despite therapeutic hypothermia (TH). Infants with mild HIE, representing 50% of those with HIE, are perceived as low risk and are currently not eligible for TH [1]. This review examines the available evidence of outcome in term infants with mild HIE. METHODS: Medline, Embase and Cochrane Clinical Trials databases were searched in March 2017. Studies with well-defined HIE grading at birth and standardised neurodevelopmental assessment at ≥18 months were included. Abnormal outcome was defined as death, cerebral palsy or standardised neurodevelopmental test score more than 1 standard deviation below the mean. RESULT: Twenty studies were included. Abnormal outcome was reported in 86/341 (25%) of infants. There was insufficient evidence to examine the effect of TH on outcome. CONCLUSION: A significant proportion of infants with mild HIE have abnormal outcome at follow up.

Ethnicity and energy stores.

The primary storage form of energy within humans is fat, which accumulates in adipose tissue including the subcutaneous, omental, mesenteric, retroperitoneal, and mammary depots. Although it has been known for some time that the size of these depots varies with sex, age, and physiologic state, it has only recently been suggested that adipose tissue partitioning, and therefore energy storage, may vary among ethnic groups. Indicators of ethnicity include race, place of birth, and culture and traditions. The literature describing energy storage in North American Indians, African Americans, Asian Americans, Mexican Americans, and Pacific Islanders is summarized and data are presented from studies comparing African American and Caucasian (Americans of Northern European descent) obese women. It is proposed that, for the purpose of research, physiologic characteristics and not ethnicity should be the basic factors used to recruit human study volunteers until we obtain mechanisms to discriminate genotype and to relate phenotype to energy storage.

Anthropometry in blacks: applicability of generalized skinfold equations and differences in fat patterning between blacks and whites.

To test the accuracy of generalized skinfold (SF) equations in blacks and to compare fat patterning in black and white adults, percent body fat (%BF) was assessed in 90 blacks and 89 whites by deuterium oxide dilution (D2O) and by generalized SF equations [Durnin and Womersely (DW), and Jackson and Pollock and Jackson et al (JP)] by using two calipers (Lange and Holtain). In blacks, JP significantly underpredicted (2.95%) and DW overpredicted (1.74%) D2O %BF with the Lange caliper. With the Holtain caliper DW successfully predicted D2O %BF (r = 0.91, SEE = 3.8%). In whites, DW overpredicted D2O %BF more than in blacks (4.94% vs 1.74%). Lower triceps-subscapular and thigh-subscapular skinfold-thickness ratios in black females and lower suprailiac-subscapular ratios in black males and females were found. It was concluded that blacks may have more visceral and upper-body fat deposition.

Intraabdominal adipose tissue and anthropometric surrogates in African American women with upper- and lower-body obesity.

It is well established that visceral adipose tissue (VAT) is associated with increased morbidity and mortality in white women. In a recent study, we found that African American women had smaller depots of VAT. To test the relation of VAT to the commonly used anthropometric surrogates for fat patterning, including waist-to-hip ratio (WHR), waist circumference, subscapular skinfold thickness, and ratio of triceps to subscapular skinfold thickness, we recruited 48 normotensive African American women > 120% of ideal body weight on the basis of WHRs > 0.85 [upper-body obesity (UBO); n = 23] and < 0.76 [lower-body obesity (LBO); n = 25]. There were no differences between groups in age, height, weight, body mass index, or percentage of body fat. VAT was determined by magnetic resonance imaging at L4-5; percentage of fat was determined by dual-energy X-ray absorptiometry. Women with UBO had significantly larger mean (+/- SEM) depots of VAT at L4-5 than did women with LBO (0.26 +/- 0.02 compared with 0.19 +/- 0.02 L). Waist circumference was the single best predictor of VAT at L4-5 in both groups of women whereas WHR was significantly associated with VAT at L4-5 only in women with UBO. In African American women, waist circumference is a better surrogate for VAT than is WHR.

A new approach for the estimation of body composition: infrared interactance.

A new method for the estimation of body composition in humans, called infrared interactance, is discussed. Infrared interactance is based on the principles of light absorption, reflection, and near-infrared spectroscopy. Body composition (percentage fat) was estimated in 53 adults (23 to 65 yr of age) by infrared interactance and compared to results from deuterium oxide dilution (r = 0.94), skinfold (r = 0.90), and ultrasound (r = 0.89) measurements. The method is safe, noninvasive, rapid, easy to use, and may prove useful to predict percentage body fat, especially in the obese.

Comparison of doubly labeled water, intake-balance, and direct- and indirect-calorimetry methods for measuring energy expenditure in adult men.

Energy expenditure (EE) of four adult men on a weight-maintenance diet was estimated by use of doubly labeled water, intake balance, and direct and indirect calorimetry. The doubly labeled water (2H218O) method was used to estimate free-living EE for 13 d. Metabolizable energy (ME) intake was used to estimate free-living EE for 1 wk. The subjects' 24-h EE was measured in a dual direct-indirect room calorimeter on 3 alternate days. Estimates of free-living EE as measured by ME intake and doubly labeled water indicate agreement between the two methods (mean difference +/- SEM, -1.04 +/- 0.63%). Measurements of EE with indirect and direct calorimetry are equivalent (mean difference 0.63 +/- 0.44%). The daily EE measured by doubly labeled water in these free-living adults over a 13-d period was 15.01% greater than the 24-h EE measured within the calorimeter.

Repeatability of 24-h energy expenditure measurements in humans by indirect calorimetry.

To estimate sources and extent of variation in energy expenditure (EE), as measured by indirect calorimetry in a room-sized human calorimeter, a number of 24-h measurements were compiled. Measured oxygen consumption and carbon dioxide production from alcohol combustion experiments averaged 101.5% of the theoretical value with a coefficient of variation (CV) of 1.4%. Experiment 1 consisted of four men who had the following averages: age, 41 y; height, 179 cm; weight, 84.6 kg; and fat, 23.5%. Five measurements, separated by 1 d, were made on each subject. Daily and basal EE averaged 2852 and 1691 kcal/d, respectively, with a within-subject CV of 2.7% and 2.4%, respectively. Experiment 2 consisted of five men who had the following averages: age, 48 y; height, 181.6 cm; weight, 87 kg; and fat, 23%. Five measurements made on each subject were separated by 1-3 wk. Daily and basal EE averaged 2619 and 1837 kcal/d, respectively, with a within-subject CV of 4.6% and 2.9%, respectively.

Visceral adipose tissue differences in black and white women.

Fat distribution and metabolic variables were studied in 8 black and 10 white age- and weight-matched obese women undergoing a 6-mo weight-reducing regimen. Fat patterning was determined by using anthropometry and computed tomography to quantitate total, subcutaneous, and visceral adipose tissue (VAT) areas at the L2-L3 and L4-L5 levels of the lumbar spine, before, during, and after a modified fast. Black women had smaller depots of VAT than white women at both the L2-L3 (P = 0.004) and L4-L5 (P = 0.054) sites. Differences persisted after an average 17.2-kg weight loss. Although waist-hip ratio was similar in both groups, black women had 23% less VAT than white women (P = 0.007). Black women had significantly lower plasma glucose (P = 0.031) and triglycerides (P = 0.006) with significantly higher plasma high-density-lipoprotein concentrations (P < 0.001). Data from this study suggest that racial differences exist in VAT and metabolic risk factors for obesity-related illness.

Energy value of moderate alcohol consumption by humans.

We investigated the effects of an equal-energetic substitution of ethanol for dietary carbohydrate in high-and low-fat diets on energy expenditure and body composition. During the controlled feeding study, subjects maintained their weights and consumed only food and drink provided by the US Department of Agriculture Beltsville Human Nutrition Research Center's Diet Study Facility. Subjects (16 men and 32 women) were divided equally into two groups and consumed either a high-or low-fat diet for 16 wk. The feeding period was divided into two 8-wk periods during which either ethanol or carbohydrate was added to the diet (5% of total daily energy intake) in a crossover design. The metabolizable energy content of the diets (with supplements) was determined for all subjects through measurement of total food intake and fecal and urinary losses for 7 d during both 8-wk periods. Energy expenditure, measured for 24 h in a room calorimeter at the end of each 8-wk period, was the same for both periods. Metabolizable energy intake and changes in total-body energy content were used to calculate the total amount of energy expended by each subject for 7 wk during each 8-wk period. Total energy expenditure for 7 wk was the same when subjects consumed either ethanol or carbohydrate. These data clearly show that on an energy basis ethanol and carbohydrate are utilized in the diet with the same efficiency. These data are consistent with the efficiency of use of alcohol for maintenance of metabolizable energy being the same as that for carbohydrate.

Seven-day validation of doubly labeled water method using indirect room calorimetry.

Carbon dioxide production, water production, and energy expenditure (EE) determined with 2H2(18)O were validated using a room calorimeter. Nine human subjects (5 males, 4 females) resided in the calorimeter for five to seven consecutive 23.5-h days. Daily carbon dioxide and water production and EE were averaged from calorimeter data and compared with 2H2(18)O results for the same period and for the following week. Isotope concentrations were measured by isotope ratio mass spectroscopy (18O) and infrared spectrophotometry (2H). Isotope clearance rates and pool sizes were determined by two multipoint methods and the two-point method. No significant differences were measured between calorimetry and 2H2(18)O results for the period within the chamber [multipoint A.M. urine 1.55% +/- 2.57 (SD) %, multipoint A.M. + P.M. urine 0.98% +/- 8.19%, two-point 1.59% +/- 4.50%]. Free-living EE was 13% +/- 7% greater. The results indicate that the 2H2(18)O method as applied is a valid technique for measuring EE, that multipoint calculation methods can be as precise as the two-point method, and that EE was greater in free-living than in calorimeter-confined conditions.

Relationship between overnight energy expenditure and BMR measured in a room-sized calorimeter.

OBJECTIVE: The purpose of this study was to determine if overnight energy expenditure, the lowest energy expenditure sustained for 60 min during the night, measured and predicted basal metabolic rate are equivalent. DESIGN: Overnight energy expenditure (ON-EE), the lowest energy expenditure sustained for 60 min during sleep (LS-EE) and basal metabolic rate (BMR) were measured two to seven times in a room-sized indirect calorimeter in 69 adult subjects. Subjects' gender, age, weight and height were also used to predict BMR (FAO/WHO/UNU, 1985) (BMR-WHO). SETTING: Beltsville Human Nutrition Research Center, Beltsville, MD, USA. RESULTS: The results from calorimetry measurements (mean +/- s.d.) included: ON-EE (6.87 +/- 0.99 MJ/d), LS-EE (6.18 +/- 0.94 MJ/d) and BMR (6.87 +/- 0.99 MJ/d). Predicted BMR mean was: BMR-WHO, 6.95 +/- 1.03. The mean within-subject difference for the calorimetry measurements were: ON-EE, 0.21 MJ/d; LS-EE, 0.16 MJ/d; and BMR, 0.34 MJ/d. Results indicate there was no significant difference between ON-EE, BMR and BMR-WHO. LS-EE was significantly lower (P < 0.0001) than ON-EE, BMR and BMR-WHO. CONCLUSION: These results indicate that while metabolic rate drops significantly below BMR during sleep, overnight metabolic rate and BMR are equivalent.

Whole-body leucine and energy metabolism in adult women.

Whole-body leucine and energy metabolism were studied in seven women, in order to examine the relationship between changes in energy expenditure and rates of protein synthesis when moving from the fasted to the fed state. The diets provided 1.1 g protein/kg/d and calories (joules) to maintain body weight. Each subject received primed, continuous intravenous infusions of L-[1-13C]-leucine for a total of 9 h, and were studied fasted for the first 4 h. Small isotopically neutral meals were fed every half hour for the last 5 h. Energy expenditure by indirect calorimetry was simultaneously measured. Leucine flux, oxidation, utilization of leucine for protein synthesis, and energy expenditure increased with feeding. There were no statistically significant correlations between rates of protein synthesis calculated from leucine flux and energy expenditure in the fasted or the fed state. Significant correlations were mainly due to sex and feeding differences. These results agree with earlier published results. A maximal cost of protein synthesis, of 5.08 kcal (21.15 kJ)/g, was determined from changes in protein synthetic rates and energy expenditure in response to feeding.

Body composition analysis of pigs by dual-energy x-ray absorptiometry.

Dual-energy x-ray absorptiometry (DXA) was evaluated as a method for measuring body composition of pigs. Forty-eight female pigs (10.2 to 60.5 kg) were killed and the whole bodies scanned on a DXA instrument. The DXA measurements provided readings of total tissue mass, percentage of fat, fat tissue mass, lean body mass, and bone mineral content. By chemical analysis, the whole body fat content of the pigs ranged from 9.3 to 24.3%, giving rise to DXA RST values (ratio of attenuation coefficients) ranging from 1.386 to 1.334. The average percentage body fat measured by DXA (18.2 +/- .9%) was not significantly different (P = .76) from the results by chemical analysis (17.8 +/- .6%); however, concordance correlation analysis revealed unacceptable accuracy in the DXA measurement due to a negative bias for smaller percentages and a positive bias for larger percentages. Total body fat measured by the two methods was also highly correlated (r = .989), and the average for DXA (7.31 +/- .62 kg) was not significantly different (P = .89) from the value for the chemical method (7.20 +/- .50 kg). The relationship between the DXA estimate of lean body mass and the amount of protein in the body by chemical analysis was described by the equation: kg protein = .227.kg DXA lean -1.28, with a correlation coefficient (r) of .968. The DXA measurements of total tissue mass and actual body weights were highly correlated (r = .999), with an acceptable concordance at the .05 level. Scans were also analyzed for regional composition of the front and back legs. It was generally difficult to determine anatomically how well soft tissue described by DXA regions corresponded to those dissected. The DXA and chemical results for regional analysis of back legs were in better agreement than those for the front legs. These results indicate that DXA may be used as a reliable method for measuring body composition of pigs, but needs more extensive calibration and may be more appropriate for total body rather than regional analysis.

Body composition analysis of small pigs by dual-energy x-ray absorptiometry.

We evaluated the use of dual-energy x-ray absorptiometry (DXA) for measuring the gross body composition of small subjects in 97 pigs that ranged from 5 to 27 kg live body weight. Scans were performed using a Lunar DPXL densitometer in the pediatric mode (Version 3.8e). The DXA scans of the live pigs provided measurements of total fat, lean, and bone mineral content. After scanning, the pigs were killed, the entire body was ground, and samples were analyzed chemically (CHEM) for fat, protein, ash, and water content. We found that DXA significantly underestimated the percentage of fat in the body (DXA, 6.9+/-.33% vs CHEM, 10.9+/-.31%, P < .001). The correlation (r) between DXA and chemical measures of percentage fat was .86 and for grams of fat it was .96. Lean tissue mass measured by DXA was highly correlated with CHEM measurements of total grams of body water (r = .99), total grams of body protein (r = .94), and lean body mass (r = .99). The average DXA bone mineral content was within 2% of the amount estimated from total body ash and the correlation between the two values was .94. The relationships between DXA and CHEM measurements for percentages of body composition of pigs that weighed between 5 and 27 kg are described by the following regression equations: %fatCHEM = 5.22 + [.817.fatDXA], (r = .86, standard error of the estimate, SEE = 1.56); %proteinCHEM = -7.8 + [.256%leanDXA], (r = .35, SEE = 2.3); %waterCHEM = -5.2 + [.808-%leanDXA], (r = .59, SEE = 3.67). These results are consistent with previously reported results and suggest that even though direct use of DXA readings may not be sufficiently accurate, the high degree of correlation indicates that with proper calibration the DXA values can be used to predict body composition.

Dimension and exercise variance in assessment center scores: a large-scale evaluation of multitrait-multimethod studies.

This study addresses 3 questions regarding assessment center construct validity: (a) Are assessment center ratings best thought of as reflecting dimension constructs (dimension model), exercises (exercise model), or a combination? (b) To what extent do dimensions or exercises account for variance? (c) Which design characteristics increase dimension variance? To this end, a large set of multitrait-multimethod studies (N = 34) were analyzed, showing that assessment center ratings were best represented (i.e., in terms of fit and admissible solutions) by a model with correlated dimensions and exercises specified as correlated uniquenesses. In this model, dimension variance equals exercise variance. Significantly more dimension variance was found when fewer dimensions were used and when assessors were psychologists. Use of behavioral checklists, a lower dimension-exercise ratio, and similar exercises also increased dimension variance.

Identification and meta-analytic assessment of psychological constructs measured in employment interviews.

There has been a growing interest in understanding what constructs are assessed in the employment interview and the properties of those assessments. To address these issues, the authors developed a comprehensive taxonomy of 7 types of constructs that the interview could assess. Analysis of 338 ratings from 47 actual interview studies indicated that basic personality and applied social skills were the most frequently rated constructs in this taxonomy, followed by mental capability and job knowledge and skills. Further analysis suggested that high- and low-structure interviews tend to focus on different constructs. Taking both frequency and validity results into consideration, the findings suggest that at least part of the reason why structured interviews tend to have higher validity is because they focus more on constructs that have a stronger relationship with job performance. Limitations and directions for future research are discussed.

Body composition analysis of chickens by dual energy x-ray absorptiometry.

Dual-energy x-ray absorptiometry (DXA) was evaluated as a method for measuring the body composition of growing broiler chickens. A total of 130 chickens, ranging in weight from 400 to 3,290 g, were scanned using a DXA instrument (Lunar DPX-L). Single whole-body scans were acquired and analyzed using pediatric total body research software (neonatal mode) or small animal total body research software (detail or high resolution mode). The DXA measurements provided readings of total tissue mass, percentage fat, fat tissue mass, lean tissue mass, and bone mineral content. After scanning, the bodies of the chickens were frozen, then, after removing the feathers, homogenized for chemical determination of fat, water, and protein content. By chemical analysis, the whole body fat content of the chickens ranged from 2.8 to 27.2%, giving rise to DXA R values (ratio of attenuation coefficients) ranging from 1.415 to 1.339. The accuracy of DXA for measuring total body fat was a function of the scanning program and mode and also the size of the bird. The best agreement between DXA and chemical measurements of percentage body fat were obtained when chickens weighing more than 2,000 g were scanned using either the small animal-detail mode or neonatal mode. None of the scan modes proved to be accurate for measuring the fat content of birds weighing less than 2,000 g. The DXA measurement of lean mass of chickens was found to be highly correlated with both total body protein (R2 = 0.90) and total body water (R2 = 0.93), but was of little value for predicting percentage values for either. The ratio of DXA bone mineral content to total body ash was 0.77; however, the correlation (R2) between the two was only 0.46. These results suggest that although the DXA technique is potentially useful for measuring body composition of chickens, considerable refinement is needed prior to routine application.

A moderate carbohydrate and fat diet does not impair strength performance in moderately trained males.

BACKGROUND: The purpose of this investigation was to study the effects of varied levels of dietary carbohydrate and fat intake on exercise training and high intensity exercise performance in moderately strength trained, aerobic trained and untrained males. METHODS: Subjects (6 strength trained, 6 aerobically trained serving as an active control group, 6 sedentary) consumed isoenergetic diets considered either high CHO/low fat (HC/LF: total energy 62% CHO, 20% fat, 18% protein) or moderate CHO and fat (MC/MF: total energy 42% CHO, 40% fat, 18% protein) in a randomly assigned crossover design. Each dietary treatment was three weeks in length. Prior to the study and following each dietary treatment, muscular strength and endurance was determined (isokinetic knee extension and flexion, standard concentric free weight bench press). RESULTS: No differences as a result of the dietary treatment were seen in isokinetic peak torque, total work production, single repetition maximum (1 RM) bench press, or number of bench press repetitions at 80% 1 RM. Self-reported exercise log data showed no dietary effect on the subject's ability to maintain training level. CONCLUSIONS: These findings indicate that varying dietary macronutrient content (HC/LF or MC/MF) had no effect on exercise training or strength exercise performance in moderately trained (aerobic and strength) or sedentary males.