The path less traveled: Using structural equation modeling to investigate factors influencing bone functional morphology.

OBJECTIVES: The relationship between an organism's mechanical environment and its bone strength has been long established by experimental research. Multiple intrinsic and extrinsic factors, including body mass, muscle strength, genetic background, and nutritional and/or hormonal status, are likely to influence bone deposition and resorption throughout the lifespan, complicating this relationship. Structural equation modeling (SEM) is uniquely positioned to parse this complex set of influences. MATERIALS AND METHODS: Data from the Third National Health and Nutrition Examination Survey, including sex, total body mass, lean body mass, exercise frequency, peak body mass, and age, were analyzed using SEM to determine how they affect bone strength both individually and combined. RESULTS: Body mass is typically the driver of cross-sectional area, but body mass and lean mass have similar effects on the polar moment of area (J). Peak body mass had a strong direct effect on J, despite decreasing strongly with increases in lean mass. Exercise also did not confer a large direct effect on cross-sectional area or J but did modify body mass and lean mass. In females, intentional weight loss was associated with decreased exercise levels. DISCUSSION: SEM is a useful tool for parsing complex systems in bone functional morphology and has the potential to uncover causal links in the study of skeletal remodeling, including factors like weight loss or exercise that may have secondary effects.

Optimized methods for detecting Salmonella Typhi in the environment using validated field sampling, culture and confirmatory molecular approaches.

AIMS: This study evaluated detection methods for Salmonella Typhi (S. Typhi) in the environment, to establish a novel pathway from field sampling to isolation of viable organisms and molecular confirmation from complex environmental samples, thus enabling environmental surveillance of typhoid. METHODS AND RESULTS: Multiple media were assessed using clinical isolates from the Public Health England's (PHE) Culture collection. The culture pathway selected consisted of a primary 2% bile broth and secondary Selenite F broth, followed by modified Chromogenic Agar for Salmonella Esterase (mCASE). A qPCR assay was adapted from a validated S. Typhi PCR panel for confirmation of isolates, with comparison to biochemical and serological tests showing good specificity. Sampling locations in Blantyre, Malawi were used to compare sampling methods. Viable S. Typhi were isolated from a mixture of trap and grab river water samples on six occasions. CONCLUSIONS: Culture of viable S. Typhi from environmental samples was possible using effective capture and culture techniques. SIGNIFICANCE AND IMPACT OF STUDY: Whilst several studies have attempted to detect S. Typhi from the environment, this is the first successful attempt to isolate the organism from river water since the 1980s. Supplementing clinical data with environmental screening offers the potential for enhanced surveillance, which might inform interventions and assess vaccination programmes.

Biomechanical implications of the onset of walking.

Changes in long bone strength associated with the onset of bipedal walking in humans have been previously documented in a longitudinal growth sample. However, it is unclear if this transition can be detected using archaeological, cross-sectional data, which likely encompass more cultural and biological variation than a single dataset of living children. Focusing on variation in cross-sectional polar second moment of area, we evaluate the ratios of femoral, tibial, and humeral strength in seven temporally diverse samples of individuals from birth to the age of eighteen years (n = 501), with subsequent comparisons to immature Late Pleistocene fossils. Using these samples, we determine whether changes related to the developmental onset of bipedality can be detected in a large, multi-population sample, test for differences in long bone strength ratios among Holocene groups that may indicate developmental differences in the onset of walking, and determine whether immature Late Pleistocene samples follow the same patterns as modern humans. Despite great variation within the Holocene sample, clear changes in these ratios are apparent around the age of the onset of walking. Humeral-to-femoral strength increases briefly prior to the age of one, with a sharp decline in relative humeral strength thereafter until age four. A similar pattern is apparent in the ratio of humeral/tibial and femoral/tibial strength. While the general pattern is consistent across all human groups sampled, these ratios vary by skeletal population, which seems to be closely related to variation in tibial length among samples. Although the extremely small fossil sample makes differences difficult to interpret, Neandertals also differ from both Late Pleistocene and Holocene modern humans in their strength ratios. Further research in this area may provide additional information about the skeletal impact of the onset of walking in the past and in additional fossil taxa.

Characterization of CMP Slurries Using Densitometry and Refractive Index Measurements.

We investigated the possibility of employing refractive index (RI) measurements for inline incoming slurry control at the point of use (POU), as an alternative to the widespread densitometry method. As such, it became necessary to determine if RI could detect smaller changes in slurry composition and, therefore, provide a tighter control. Three industrially-relevant silica-based slurries, namely, Fujimi PL-7106, Klebosol 1501-50, and CMC W7801, were characterized using both densitometry and RI measurements. Initial solutions of the three slurries were prepared and increasingly small amounts of ultrapurified water (UPW) were added to study the change in slurry properties. Results showed that both density and RI decreased linearly with the addition of water for all three slurries, with the 1501-50 being the most sensitive to water addition. A linear correlation between the two properties was found, with R² values that exceeded 0.95 in all cases. Furthermore, the approximate limit of detection of both metrology tools was estimated based on the slope of the fitting line and resolution. When compared to densitometry, RI was found to be the far superior method for detecting smaller changes in water concentration.

Weight-based enoxaparin dosing for venous thromboembolism prophylaxis in the obese trauma patient.

BACKGROUND: Limited data exist regarding the efficacy of weight-based dosing of low-molecular weight heparin for venous thromboembolism (VTE) prophylaxis in obese trauma patients. METHODS: Consecutive obese trauma patients were placed on a weight-based protocol for VTE prophylaxis (enoxaparin .5 mg/kg subcutaneously every 12 hours). Peak anti-Xa levels were drawn, and bilateral lower extremity duplex ultrasound was performed. The incidence of VTE and bleeding complications were recorded. RESULTS: Eighty-six patients met the study criteria. Seventy-four patients achieved target prophylactic anti-Xa concentrations, with a mean level of .42 ± .01 IU/mL. Eighteen patients were found to have deep vein thrombosis. However, in 16 of these patients, deep vein thrombosis was diagnosed before weight-based low-molecular weight heparin initiation. No bleeding complications occurred, and no symptomatic pulmonary emboli were identified. CONCLUSIONS: In obese trauma patients, weight-based enoxaparin is an efficacious regimen that provides adequate VTE prophylaxis, as measured by anti-Xa levels, and appears to be safe without bleeding complications.