Metrics for estimating vapour pressure deviation from ideality in binary mixtures.

A novel method is introduced for estimating the degree of interactions occurring between two different compounds in a binary mixture resulting in deviations from ideality as predicted by Raoult's law. Metrics of chemical similarity between binary mixture components were used as descriptors and correlated with the Root-Mean Square Error (RMSE) associated with Raoult's law calculations of total vapour pressure prediction, including Abraham descriptors, sigma moments, and several chemical properties. The best correlation was for a quantitative structure-activity relationship (QSAR) equation using differences in Abraham parameters as descriptors (r2 = 0.7585), followed by a QSAR using differences in COSMO-RS sigma moment descriptors (r2 = 0.7461), and third by a QSAR using differences in the chemical properties of log KAW, melting point, and molecular weight as descriptors (r2 = 0.6878). Of these chemical properties, Δlog KAW had the strongest correlation with deviation from Raoult's law (RMSE) and this property alone resulted in an r2 of 0.6630. These correlations are useful for assessing the expected deviation in Raoult's law estimations of vapour pressures, a key property for estimating inhalation exposure.

Ranking REACH registered neutral, ionizable and ionic organic chemicals based on their aquatic persistency and mobility.

The contaminants that have the greatest chances of appearing in drinking water are those that are mobile enough in the aquatic environment to enter drinking water sources and persistent enough to survive treatment processes. Herein a screening procedure to rank neutral, ionizable and ionic organic compounds for being persistent and mobile organic compounds (PMOCs) is presented and applied to the list of industrial substances registered under the EU REACH legislation as of December 2014. This comprised 5155 identifiable, unique organic structures. The minimum cut-off criteria considered for PMOC classification herein are a freshwater half-life >40 days, which is consistent with the REACH definition of freshwater persistency, and a log Doc < 4.5 between pH 4-10 (where Doc is the organic carbon-water distribution coefficient). Experimental data were given the highest priority, followed by data from an array of available quantitative structure-activity relationships (QSARs), and as a third resort, an original Iterative Fragment Selection (IFS) QSAR. In total, 52% of the unique REACH structures made the minimum criteria to be considered a PMOC, and 21% achieved the highest PMOC ranking (half-life > 40 days, log Doc < 1.0 between pH 4-10). Only 9% of neutral substances received the highest PMOC ranking, compared to 30% of ionizable compounds and 44% of ionic compounds. Predicted hydrolysis products for all REACH parents (contributing 5043 additional structures) were found to have higher PMOC rankings than their parents, due to increased mobility but not persistence. The fewest experimental data available were for ionic compounds; therefore, their ranking is more uncertain than neutral and ionizable compounds. The most sensitive parameter for the PMOC ranking was freshwater persistency, which was also the parameter that QSARs performed the most poorly at predicting. Several prioritized drinking water contaminants in the EU and USA, and other contaminants of concern, were identified as PMOCs. This identification and ranking procedure for PMOCs can be part of a strategy to better identify contaminants that pose a threat to drinking water sources.

Soldier-relevant body borne load impacts minimum foot clearance during obstacle negotiation.

Soldiers often trip and fall on duty, resulting in injury. This study examined ten male soldiers' ability to negotiate an obstacle. Participants had lead and trail foot minimum foot clearance (MFC) parameters quantified while crossing a low (305 mm) and high (457 mm) obstacle with (19.4 kg) and without (6 kg) body borne load. To minimize tripping risk, participants increased lead foot MFC (p = 0.028) and reduced lead (p = 0.044) and trail (p = 0.035) foot variability when negotiating an obstacle with body borne load. While obstacle height had no effect on MFC (p = 0.273 and p = 0.126), placing the trail foot closer to the high obstacle when crossing with body borne load, resulted in greater lead (R = 0.640, b = 0.241, p = 0.046) and trail (R = 0.636, b = 0.287, p = 0.048) MFC. Soldiers, when carrying typical military loads, may be able to minimize their risk of tripping over an obstacle by creating a safety margin via greater foot clearance with reduced variability.

Lower limb flexion posture relates to energy absorption during drop landings with soldier-relevant body borne loads.

Fifteen military personnel performed 30-cm drop landings to quantify how body borne load (light, ∼6 kg, medium, ∼20 kg, and heavy, ∼40 kg) impacts lower limb kinematics and knee joint energy absorption during landing, and determine whether greater lower limb flexion increases energy absorption while landing with load. Participants decreased peak hip (P = 0.002), and knee flexion (P = 0.007) posture, but did not increase hip (P = 0.796), knee (P = 0.427) or ankle (P = 0.161) energy absorption, despite exhibiting greater peak hip (P = 0.003) and knee (P = 0.001) flexion, and ankle (P = 0.003) dorsiflexion angular impulse when landing with additional load. Yet, when landing with the light and medium loads, greater hip (R(2) = 0.500, P = 0.003 and R(2) = 0.314, P = 0.030) and knee (R(2) = 0.431, P = 0.008 and R(2) = 0.342, P = 0.022) flexion posture predicted larger knee joint energy absorption. Thus, military training that promotes hip and knee flexion, and subsequently greater energy absorption during landing, may potentially reduce risk of musculoskeletal injury and optimize soldier performance.

Body borne loads impact walk-to-run and running biomechanics.

The purpose of this study was to perform a biomechanics-based assessment of body borne load during the walk-to-run transition and steady-state running because historical research has limited load carriage assessment to prolonged walking. Fifteen male military personnel had trunk and lower limb biomechanics examined during these locomotor tasks with three different load configurations (light, ∼6 kg, medium, ∼20 kg, and heavy, ∼40 kg). Subject-based means of the dependent variables were submitted to repeated measures ANOVA to test the effects of load configuration. During the walk-to-run transition, the hip decreased (P=0.001) and knee increased (P=0.004) their contribution to joint power with the addition of load. Additionally, greater peak trunk (P=0.001), hip (P=0.001), and knee flexion (P<0.001) moments and trunk flexion (P<0.001) angle, and reduced hip (P=0.001) and knee flexion (P=0.001) posture were evident during the loaded walk-to-run transition. Body borne load had no significant effect (P>0.05) on distribution of lower limb joint power during steady-state running, but increased peak trunk (P<0.001), hip (P=0.001), and knee (P=0.001) flexion moments, and trunk flexion (P<0.001) posture were evident. During the walk-to-run transition the load carrier may move joint power production distally down the kinetic chain and adopt biomechanical profiles to maintain performance of the task. The load carrier, however, may not adopt lower limb kinematic adaptations necessary to shift joint power distribution during steady-state running, despite exhibiting potentially detrimental larger lower limb joint loads. As such, further study appears needed to determine how load carriage impairs maximal locomotor performance.

Predicting hexadecane-air equilibrium partition coefficients (L) using a group contribution approach constructed from high quality data.

A group contribution-based quantitative structure-property relationship (QSPR) for the hexadecane-air equilibrium partition coefficients (L) of organic chemicals is developed using the iterative fragment selection (IFS) approach. This new QSPR includes in its training and external validation data sets L values for a large number of structurally complex chemicals measured by the same group using consistent methods. The resulting QSPR has better predictive power than other prediction methods trained primarily using data for chemicals of simpler structures, and measurements of L values from diverse sources. For a subset of chemicals in which the L values have non-additive effects caused by intramolecular hydrogen bonds, the new QSPR gives much better performance in comparison to the most commonly used prediction method.

Associations between lower limb muscle activation strategies and resultant multi-planar knee kinetics during single leg landings.

OBJECTIVES: Anterior cruciate ligament injury prevention programs purportedly improve knee joint loading through beneficial modification of lower limb neuromuscular control strategies and joint biomechanics, but little is known about how these factors relate during single-legged landings. Thus, we examined the relationship between explicit lower limb muscular pre-activity patterns and knee joint biomechanics elicited during such landings. DESIGN: Randomized controlled trial. METHODS: Thirty-five female athletes had 3D knee joint biomechanics and lower limb EMG data recorded during a series of single-leg landings. Regression analysis assessed the relationship between pre-activity of vastus lateralis, lateral hamstring and rectus femoris with peak knee flexion angle and moment, and external anterior tibial shear force. Vastus lateralis, lateral hamstring and vastus lateralis:lateral hasmtring co-contraction assessed the relationship with knee abduction angle and moment. RESULTS: Greater pre-activity of rectus femoris predicted increased peak anterior tibial shear force (R(2)=0.235, b=2.41 and P=0.003) and reduced knee flexion moment (R(2)=0.131, b=-0.591, and P=0.032), while greater lateral hamstring predicted decreased peak knee flexion angle (R(2)=0.113, b=8.96 and P=0.048). No EMG pre-activity parameters were predictors (P>0.05) for knee abduction angle and moment. CONCLUSIONS: Current outcomes suggest reducing reliance on quadriceps activation may be beneficial during single-legged landings. It also, however, may be required for adequate joint stability during such maneuvers. Further research is needed to determine if inadequate hamstring activation, rather than elevated quadriceps activation, leads to hazardous loading during single-legged landings.

Sex and limb differences in hip and knee kinematics and kinetics during anticipated and unanticipated jump landings: implications for anterior cruciate ligament injury.

OBJECTIVES: In this study, the effects of temporal changes in unanticipated (UN) prelanding stimuli on lower limb biomechanics and the impact of sex and limb dominance on these variables during single-leg landings were determined. It was hypothesised that reductions in the time of prelanding UN stimuli, female sex, and the non-dominant limb would significantly increase high-risk landing biomechanics during UN jump landings. METHODS: 26 (13 men and 13 women) had initial contact (IC) and peak stance (0-50%) phase (PS) lower limb joint kinematics and kinetics quantified during anticipated (AN) and UN single-leg (left and right) landings. Postlanding jump direction was governed via one of two randomly ordered light stimuli, presented either before initiation of the jump (AN), or 600 ms (UN1), 500 ms (UN2) or 400 ms (UN3) immediately before ground contact. RESULTS: Statistically significant (p<0.05) differences in IC hip posture and PS hip and knee internal rotation moments occurred in UN compared with AN landings. Differences were not observed, however, among UN conditions for any biomechanical comparisons. Significant (p<0.05) differences in specific IC and PS hip and knee postures and loads occurred between sexes and limbs. Neither of these factors, however, influenced movement condition effects. CONCLUSION: UN landings induce modifications in landing biomechanics that may increase anterior cruciate ligament injury risk in both men and women. These modifications, however, do not appear overly sensitive to the timing of the UN stimulus, at least within a temporal range affording a successful movement response. Expanding UN training to include even shorter stimulus-response times may promote the additional central control adaptations necessary to manoeuvre safely within the random sports setting.

Are risk and protective factors for substance use consistent across historical time?: national data from the high school classes of 1976 through 1997.

Researchers have seldom examined whether risk and protective factors are consistently linked to substance use across historical time. Using nationally representative data collected from 22 consecutive cohorts of high school seniors (approximate N = 188,000) from the Monitoring the Future (MTF) project, we investigated whether correlates of substance use changed across historical time. We found a high degree of consistency across historical time in predictors of past month cigarette use, past month alcohol use, past year marijuana use, and past year cocaine use. Some predictors such as religiosity, political beliefs, truancy, and frequent evenings out were consistently linked to substance use. The consistency of other predictors such as region, parental education, and college plans was contingent in part upon historical time period, the particular substance, and its level of use.

A c-fos/Estrogen receptor fusion protein promotes cell cycle progression and proliferation of human cancer cell lines.

c-fos is the prototypic member of a family of transcription factors that regulate many cellular processes, including proliferation. c-fos heterodimerizes with jun family members to form the AP-1 transcription factor complex which binds specific DNA recognition elements in the promoters of many genes. Following rapid induction in response to serum or growth factors, c-fos regulates expression of downstream target genes involved in cellular proliferation. Although much work has focused on activation of cell cycle regulatory genes by c-fos, less is known about negative regulation of gene expression by this transcription factor. The cyclin-dependent kinase (cdk) inhibitor p21(Cip1/WAF1) is a negative regulator of cdk activity, thereby impeding cell cycle progression. By sequence analysis, we identified a putative AP-1 element in the p21(Cip1/WAF1) promoter. To investigate how this site regulated p21(Cip1/WAF1) expression and mitigate external effects on c-fos expression, we used a c-fos/estrogen receptor (c-fosER) fusion construct in which this transcription factor is conditionally activated by estradiol. In the presence of estradiol, c-fosER downregulated p21(Cip1/WAF1) promoter activity. This inhibition was dependent on the putative AP-1 site. Activation of c-fosER induced cell cycle progression and proliferation in a manner similar to serum stimulation. We concluded that activation of c-fosER mediated transcriptional inhibition of p21(Cip1/WAF1) through a previously uncharacterized AP-1 site, revealing an important role for c-fos in negative control of cell cycle regulatory genes.

Transcriptional inhibition of matrix metalloproteinase 9 (MMP-9) activity by a c-fos/estrogen receptor fusion protein is mediated by the proximal AP-1 site of the MMP-9 promoter and correlates with reduced tumor cell invasion.

Tumor cell invasion of basement membranes is one of the hallmarks of malignant transformation. Tumor cells secrete proteolytic enzymes known as matrix metalloproteinases (MMPs) which degrade extracellular matrix molecules. Increased expression of MMP-9 has been associated with acquisition of invasive phenotype in many tumors. However, multiple mechanisms for regulation of MMP-9 gene expression by tumor cell lines have been proposed. A number of transcription factor binding sites have been characterized in the upstream regulatory region of the MMP-9 gene, including those for AP-1. To determine how a specific AP-1 family member, c-fos, regulates MMP-9 promoter activity through these sites, we used an expression vector containing the c-fos coding region fused to the estrogen receptor (ER) ligand binding domain. This construct is activated upon binding estradiol. Stable expression of this construct in ER negative squamous cell carcinoma (SCC) lines produced an estradiol dependent decrease in the number of cells that migrated through a reconstituted basement membrane. This decreased invasiveness was accompanied by estradiol dependent downregulation of MMP-9 activity as determined by gelatin zymography. Estradiol also produced transcriptional downregulation of an MMP-9 promoter construct in cells transiently transfected with the c-fosER expression vector. This downregulation was mediated by the AP-1 site at -79 bp in the MMP-9 promoter. We concluded that the proximal AP-1 site mediated the transcriptional downregulation of the MMP-9 promoter by a conditionally activated c-fos fusion protein.

Racism and the physical and mental health status of African Americans: a thirteen year national panel study.

This paper examined the relationships between the experiences and perceptions of racism and the physical and mental health status of African Americans. The study was based upon thirteen year (1979 to 1992), four wave, national panel data (n = 623) from the National Survey of Black Americans. Personal experiences of racism were found to have both adverse and salubrious immediate and cumulative effects on the physical and mental well-being of African Americans. In 1979-80, reports of poor treatment due to race were inversely related to subjective well-being and positively associated with the number of reported physical health problems. Reports of negative racial encounters over the 13-year period were weakly predictive of poor subjective well-being in 1992. A more general measure of racial beliefs, perceiving that whites want to keep blacks down, was found to be related to poorer physical health in 1979-80, better physical health in 1992, and predicted increased psychological distress, as well as, lower levels of subjective well-being in 1992. In conclusion, the authors suggested future research on possible factors contributing to the relationship between racism and health status among African Americans.

Documenting workload to better integrate clinical and distributive services.

Use of workload and work-flow documentation in two pharmacy satellites to evaluate pharmacists' productivity is described. Workload was evaluated during 14 consecutive days in May 1983 and 7 consecutive days in May 1984. All pharmacists and technicians working in the satellites recorded times for their activities on a form that listed every possible activity; interruptions such as answering the telephone, responding to walking requests, replacing stock, and lunches and break times were also recorded. Concurrently, the clinical coordinator observed and evaluated work performed for four-hour time blocks at least once each day. Analysis of workload and work-flow information identified problems with scheduling, priorities, interruptions, and pharmacists' knowledge of clinical pharmacy practice. Based on these observations, the following changes were implemented: pharmacists were scheduled to work either inside or outside the satellites for two-week or one-month time periods, priorities were assigned to certain tasks performed inside or outside the satellites, job assignments were made based on the pharmacist's capabilities and the needs of the patient-care areas, a form for documenting potential problem orders was created, and pharmacists were evaluated monthly and given one-on-one instruction by the clinical coordinator. Documentation of time use identified problems and led to changes in assignments that better integrated clinical, educational, and distributive responsibilities for the purpose of providing more efficient and effective services.

Stress urinary incontinence: a simple and practical approach to diagnosis and treatment.

A study to evaluate the efficacy of a simple and inexpensive diagnostic and therapeutic approach to stress incontinence in 46 elderly women is described. The treatment had two aspects: estrogens, both orally and topically, and a pelvic floor exercise program. The study shows that stress incontinence and stress incontinence with urgency incontinence in non-institutionalized, ambulant elderly women can be diagnosed and successfully treated in the great majority of cases without the need for expensive and potentially hazardous diagnostic and therapeutic modalities.