Latent variable modeling to develop a robust proxy for sensitive behaviors: application to latrine use behavior and its association with sanitation access in a middle-income country.

BACKGROUND: Globally, diarrhea is a leading cause of child morbidity and mortality. Although latrines are integral for reducing enteric pathogen transmission, several studies have shown no evidence that latrine ownership improved child health. There are a number of explanations for these results. One explanation is that latrine access does not equate to latrine use. Latrine use, however, is difficult to accurately ascertain, as defecation behavior is often stigmatized. To address this measurement issue, we measure latrine use as a latent variable, indicated by a suite of psychosocial variables. METHODS: We administered a survey of 16 defecation-related psychosocial questions to 251 individuals living in rural Ecuador. We applied latent class analysis (LCA) to these data to model the probability of latrine use as a latent variable. To account for uncertainty in predicted latent class membership, we used a pseudo-class approach to impute five different probabilities of latrine use for each respondent. Via regression modeling, we tested the association between household sanitation and each imputed latrine use variable. RESULTS: The optimal model presented strong evidence of two latent classes (entropy = 0.86): consistent users (78%) and inconsistent users (22%), predicted by 5 of our 16 psychosocial variables. There was no evidence of an association between the probability of latrine use, predicted from the LCA, and household access to basic sanitation (OR = 1.1, 95% CI = 0.6-2.1). This suggests that home access to a sanitation facility may not ensure the use of the facility for every family member at all times. CONCLUSION: Effective implementation and evaluation of sanitation programs requires accurate measurement of latrine use. Psychosocial variables, such as norms, perceptions, and attitudes may provide robust proxy-measures. Future longitudinal studies will help to strengthen the use of these surrogate measures, as many of these factors may be subject to secular trends. Additionally, subgroup analyses will elucidate how our  proxy indicators of latrine defecation vary by individual-level characteristics.

Neighbourhood influence on the fourth dose of diphtheria-tetanus-pertussis vaccination.

OBJECTIVES: Using 542,159 vaccination records from children born between April 1, 2007, and March 31, 2012, in the Michigan Care Improvement Registry and data from the American Community Survey, we determine if neighbourhood-level characteristics at the Census tract level and block level are associated with low uptake of the fourth dose of diphtheria-tetanus-acellular pertussis vaccine (DTaP4). STUDY DESIGN: This study was a cross-sectional study. METHODS: We used exploratory factor analysis to determine important socio-economic factors at the Census block level and tract level. We then used generalised estimating equations to test the relationship between block- and tract-level socio-economic factors and DTaP4 uptake. RESULTS: DTaP4 coverage was 88.6% (95% confidence interval [CI]: 88.4%-88.7%) in Michigan. At the Census tract level, two factors surfaced as important for DTaP4 vaccination: 'affluence' (Cronbach's alpha = 0.88) and 'socio-economic disadvantage' (Cronbach's alpha = 0.89). At the Census block level, one factor was important: 'affluence' (Cronbach's alpha = 0.90). Affluence may relate to knowledge about medical exemptions and antivaccination sentiment, while socio-economic disadvantage may indicate limited access to healthcare resources. Children in high-affluence tracts had 1.08% lower vaccination coverage (95% CI: -1.62% to -0.55%) than children in low affluence tracts. Children in low socio-economic disadvantage tracts had 2.92% higher coverage than children in high socio-economic disadvantage tracts (95% CI: 2.58%-3.26%). CONCLUSIONS: This study articulates the need to further understand the contribution of neighbourhood-level characteristics, from both affluent and socioeconomically disadvantaged areas to low vaccination rates. Developing a better understanding of these social environmental factors will help determine useful community-level interventions to improve vaccination rates and reduce disease burden.

Self-efficacy, neighborhood walking, and fall history in older adults.

This cross-sectional study examined the association of self-efficacy with neighborhood walking in older adult (mean age = 76.1, SD = 8.34) fallers (n = 108) and nonfallers (n = 217) while controlling for demographic characteristics and mobility. Hierarchical multiple regression indicated that the full model explained 39% of the variance in neighborhood walking in fallers (P < .001) and 24% in nonfallers (P < .001). Self-efficacy explained 23% of the variance in fallers (P < .001) and 11% in nonfallers (P < .001). Neighborhood walking was significantly associated with self-efficacy for individual barriers in both groups. Self-efficacy for neighborhood barriers trended toward significance in fallers (ß = .18, P = .06). Fall history did not moderate the relationship between self-efficacy and neighborhood walking. Walking interventions for older adults should address self-efficacy in overcoming individual walking barriers. Those targeting fallers should consider addressing self-efficacy for overcoming neighborhood barriers.

Resprouting as a key functional trait: how buds, protection and resources drive persistence after fire.

Resprouting as a response to disturbance is now widely recognized as a key functional trait among woody plants and as the basis for the persistence niche. However, the underlying mechanisms that define resprouting responses to disturbance are poorly conceptualized. Resprouting ability is constrained by the interaction of the disturbance regime that depletes the buds and resources needed to fund resprouting, and the environment that drives growth and resource allocation. We develop a buds-protection-resources (BPR) framework for understanding resprouting in fire-prone ecosystems, based on bud bank location, bud protection, and how buds are resourced. Using this framework we go beyond earlier emphases on basal resprouting and highlight the importance of apical, epicormic and below-ground resprouting to the persistence niche. The BPR framework provides insights into: resprouting typologies that include both fire resisters (i.e. survive fire but do not resprout) and fire resprouters; the methods by which buds escape fire effects, such as thick bark; and the predictability of community assembly of resprouting types in relation to site productivity, disturbance regime and competition. Furthermore, predicting the consequences of global change is enhanced by the BPR framework because it potentially forecasts the retention or loss of above-ground biomass.

Accessing and selecting word meaning in autism spectrum disorder.

BACKGROUND: Comprehension difficulties are commonly reported in autism spectrum disorder (ASD) but the causes of these difficulties are poorly understood. This study investigates how children with ASD access and select meanings of ambiguous words to test four hypotheses regarding the nature of their comprehension difficulties: semantic deficit, weak central coherence, reduced top-down control and inhibition deficit. METHODS: The cross-modal semantic priming paradigm was used. Children heard homonym primes in isolation or as final words in sentences biased towards the subordinate meaning and then named picture targets depicting dominant or subordinate associates of homonyms. RESULTS: When homonyms were presented in isolation, children with ASD and controls showed priming for dominant and subordinate pictures at 250ms ISI. At 1,000ms ISI, the controls showed dominant (but not subordinate) priming whilst the ASD group did not show any priming. When homonyms were presented in subordinate sentence contexts, both groups only showed priming for context-appropriate (subordinate) meanings at 250ms ISI, suggesting that context has an early influence on meaning selection. At 1,000ms ISI the controls showed context-appropriate (but not inappropriate) priming whereas the ASD group showed both appropriate and inappropriate priming. CONCLUSIONS: Children with ASD showed intact access to semantic information early in the time course of processing; however, they showed impairments in the selection of semantic representations later in processing. These findings suggest that a difficulty with initiating top-down strategies to modulate online semantic processing may compromise language comprehension in ASD. Implications for intervention are discussed.

Muscle Weakness and Physical Disability in Older Americans: Longitudinal Findings from the U.S. Health and Retirement Study.

IMPORTANCE: Muscle weakness is an important indicator of disability, chronic disease and mortality. While we recently proposed sex/race specific grip strength cutpoints for clinical muscle weakness in a diverse, nationally representative sample of older Americans, the extent to which these cutpoints predict physical disability remains unknown. OBJECTIVE: To examine whether sex/race specific muscle weakness cutpoints predict physical disability status in a nationally representative sample of Americans age 65+. DESIGN: We used data from the 2006-2010 Health and Retirement Study. Fully-adjusted, weighted multinomial logistic regression models were used to quantify the odds of experiencing the onset, progression or persistence of disability in activities of daily living (ADL) among weak versus non-weak individuals over a 2-year period. SETTING: General community, nationally representative sample of older Americans. PARTICIPANTS: Population-based, community dwelling sample of older American adults aged 65-years+; 57 percent were women, 91% were White and the mean age was 75 years. Main Outcome(s) and Measure(s): The primary outcome of interest was disability dynamics, defined by changes in ADL status across at 2- year period. The primary exposure was clinical muscle weakness as defined by previously identified cutpoints. Hypotheses were formulated before analyses were conducted. RESULTS: In this nationally representative sample (n= 8,725), 44% of individuals were classified as weak at baseline. At follow-up, 55% remained independent with no change in their ADL status, 11% had an onset of disability and 4% progressed in their disability status. The odds of experiencing an onset of ADL disability was 54% higher among weak individuals compared those who were not weak at baseline (OR= 1.54, 95% CI= 1.54, 1.5, p<.0001); the odds of experiencing a progression in physical disability status was 2.16 times higher among those who were weak at baseline compared to non-weak individuals (OR= 2.16, 95% CI= 2.15, 2.16, p<.0001). CONCLUSIONS: This is the first study to use grip strength weakness cut-points to identify those who may be at greatest risk for experiencing physical disability in later life. Results underscore the importance of using population-specific cutpoints for clinical weakness in order to identify individuals at greatest risk for adverse health outcomes.

Double immunocytochemical labeling of cell and tissue samples with monoclonal anti-bromodeoxyuridine.

We describe a new monoclonal antibody (designated Bu20a) against bromodeoxyuridine (BrdU). This antibody was selected by screening against human tissues using the APAAP technique, and shows no crossreactivity with normal nuclei. It stains BrdU incorporated into the nuclei of a wide range of cell types, including human tonsil lymphoid cells, normal mouse tissues, and human tumors growing in nude mice. A double-labeling technique is described using this antibody in which cell smears or tissue sections are first labeled by an immunoperoxidase procedure for a cellular antigen (e.g., mouse or human histocompatibility class II antigen, T-lymphocyte antigen, keratin) and BrdU is then detected by indirect immunofluorescence. This procedure, which was applied to a variety of human and animal cells and tissues, is of wide potential value in analyzing the phenotype of S-phase cells and in co-localizing antigen expression and BrdU incorporation in tissue sections.

The immunolocalisation of the neuroendocrine specific protein PGP9.5 during neurogenesis in the rat.

We have examined the immunolocalisation of the protein gene product (PGP) 9.5 during neurogenesis in the rat embryo. PGP9.5 was first present at 11.5 days gestation (E11.5): all morphologically recognisable nerve cell bodies and fibres were immunoreactive. In routinely processed, wax-embedded tissues, using a standard immunocytochemical technique, PGP9.5 polyclonal antibody specifically demonstrated the developing nervous system and primitive adrenal chromaffin cells.

An improved mouse sperm-oocyte plasmalemma binding assay: studies on characteristics of sperm binding in medium with or without glucose.

Sperm binding to the oocyte plasmalemma is crucial to subsequent steps in fertilization. However, the usual in vitro assay for sperm-oocyte binding does not distinguish between nonspecific attachment and specific binding leading to fusion and penetration. Since zona pellucida-free pronuclear zygotes should not bind sperm (because of the block to polyspermy at the level of the oocyte membrane), a procedure has been developed to remove virtually all sperm from zona-free pronuclear zygotes (2PNZ). After six washes with a 90-microm-bore pipette, there were 0.5 +/- 0.2 sperm/2PNZ (n = 83). Therefore, these washing conditions were used to define sperm-oocyte binding. The relationship of binding to oocyte penetration was determined for outbred mouse oocytes coincubated in complete medium with (B6 x 129)F1 hybrid sperm (10(7)/ml). Binding was maximal (29 +/- 5 sperm per oocyte) during the first 30 minutes but decreased significantly to 4.6 +/- 1.4 by 60 minutes of coincubation (over 10 trials). Oocyte penetration was 99 +/- 1% by 30 minutes, while the number of decondensed sperm nuclei per oocyte increased significantly to 7.5 +/- 0.6 at 60 minutes. These data suggest that the block to polyspermy involves detachment of bound sperm. Similar coincubations were carried out in medium without glucose (NoG), as this medium has been reported to inhibit fusion without affecting binding. However, binding was only 11 +/- 2 at 30 minutes but increased to 25 +/- 4 at 60 minutes, suggesting that binding was retarded in NoG. When gametes were coincubated in NoG for 5 hours, about half of the oocytes were penetrated, suggesting that the lack of glucose did not inhibit fusion but instead delayed it. These data suggest that if sperm binding is to be determined in complete medium, the time of the block to polyspermy should be determined prior to selecting the appropriate time to assay binding. Furthermore, using the same coincubation period for the binding assay in control and treated sperm may not be appropriate if the treatment alters the time of maximal binding.

Analgesic efficacy and safety of single-dose oral and intramuscular ketorolac tromethamine for postoperative pain.

The efficacy and safety of the analgesic drug ketorolac tromethamine in the treatment of moderate to very severe postoperative pain was assessed in five dose-ranging studies with single-dose, double-blind, randomized, parallel-group designs. The drug was administered orally (2.5-200 mg, 352 patients in three trials) and intramuscularly (5-90 mg, 395 patients in two trials), and compared with placebo and reference drugs. Patients subjectively evaluated pain intensity and relief using verbal categoric and visual analog scales; efficacy values included pain intensity difference (PID), summed PID, and total pain relief. Oral ketorolac 10, 12.5, 100, and 200 mg were each statistically significantly superior to placebo in all efficacy measurements, and 10 mg was equivalent to intramuscular morphine 10 mg. Intramuscular ketorolac 90 mg was superior to and 10 and 30 mg were similar to intramuscular morphine 12 mg, and all of these ketorolac doses were superior to intramuscular morphine 6 mg. Intramuscular ketorolac 10 and 30 mg were superior to intramuscular meperidine 50 and 100 mg. Ketorolac was well tolerated, with rates of adverse events generally lower than those of the opiate comparators. Ketorolac doses of 2.5 and 5 mg were less effective than higher doses; 10 mg or more resulted in faster onset of action and greater peak efficacy; 90 mg or more gave more prolonged analgesic effects.

The regeneration niche of the grey mangrove (Avicennia marina): effects of salinity, light and sediment factors on establishment, growth and survival in the field.

Field observations of seedlings and saplings of Avicennia marina showed patterns that correlated with salinity, light and sediment. Models that account for these observations were subsequently tested in a series of field experiments. Establishment varied within an estuary under controlled conditions but was not related to salinity or sediment type. Seedling survival was uniform over 3 years regardless of position in estuary and sediment type. Seedling densities and survival under canopies or in canopy gaps were not significantly different. However, seedling growth and density of saplings were greater in canopy gaps. Experiments involving manipulations of canopies showed no differences in seedling survival under canopies or in light gaps, but addition of slow-release fertilizer enhanced growth and survival in canopy gaps and under canopies. Long-term comparison of areas denuded of a canopy and with sediment disturbance showed enhanced establishment and survival when compared with areas with canopy gaps but with undisturbed sediments. Overall there appears to be no restriction to establishment of propagules within mangrove stands other than the supply of propagules and tidal or wave action. In contrast, recruitment to the sapling stage appears to be restricted by light and sediment resources. We suggest that propagules need to establish in a regeneration niche for seedling recruitment to the sapling stage. This differs from the view that seedlings in the under-storey are analogous to a seed pool in the soil.

Glycine absorption from irrigation fluid during endoscopic resection of rectal tumours.

A significant rise in plasma glycine concentration was observed in nine elderly patients undergoing endoscopic transanal resection of rectal tumours using glycine solution for irrigation. Despite the obvious absorption of glycine, plasma sodium concentration and osmolality were not significantly altered, except in a patient whose rectal wall was perforated. In this case plasma sodium and osmolality fell, and the patient developed hyperammonaemia. Potentially adverse metabolic consequences may occur when there are surgical complications, but in the absence of such problems the absorption of glycine appears to cause little effect.

Liver function tests in patients receiving parenteral nutrition.

A 5-year prospective study was performed to monitor liver function tests (LFTs) in patients receiving total parenteral nutrition (TPN). A gradual and progressive rise was seen in the plasma concentration of bilirubin, aspartate transaminase, and alkaline phosphatase. The rate of rise was not increased in patients with LFT abnormalities before the start of TPN. Half of the patients had an episode of sepsis during TPN, but overall abnormal LFTs did not appear more common in these patients than in those without obvious sepsis. Patients with malignant disease, those requiring long-term TPN, and those requiring a nonstandard TPN regimen were more likely to develop raised LFTs.

Fusion of contrast-enhanced breast MR and mammographic imaging data.

Increasing use is being made of Gd-DTPA contrast-enhanced MRI (CE-MRI) for breast cancer assessment since it provides three-dimensional (3D) functional information via pharmacokinetic interaction between contrast agent and tumour vascularity, and because it is applicable to women of all ages as well as patients with post-operative scarring. CE-MRI is complementary to conventional X-ray mammography, since it is a relatively low-resolution functional counterpart of a comparatively high-resolution 2D structural representation. However, despite the additional information provided by MRI, mammography is still an extremely important diagnostic imaging modality, particularly for several common conditions such as ductal carcinoma in situ (DCIS) where it has been shown that there is a strong correlation between microcalcification clusters and malignancy. Pathological indicators such as calcifications and fine spiculations are not visible in CE-MRI and therefore there is clinical and diagnostic value in fusing the high-resolution structural information available from mammography with the functional data acquired from MRI. This article is a clinical overview of the results of a technique to transform the coordinates of regions of interest (ROIs) from the 2D mammograms to the spatial reference frame of the contrast-enhanced MRI volume. An evaluation of the fusion framework is demonstrated with a series of clinical cases and a total of 14 patient examples.

Handicap in stroke survivors.

BACKGROUND AND PURPOSE: As survival following stroke improves, individuals are more likely to live with the aftermath of stroke rather than immediately die from it. The purpose of this study was to examine the consequences of stroke on the life activities of survivors in the social realm (stroke handicap) using the framework of the World Health Organization's International Classification of Impairments, Disabilities and Handicaps. METHODS: Multivariate analysis of variance was applied to cross-sectional data from a clinical study to investigate the correlates of handicap in a cohort of hemispheric stroke survivors at 3 months (n = 145) and at 1 year (n = 135) after stroke onset. Handicap was assessed with the Reintegration to Normal Living Index, impairment by the Adams' Hemispheric Stroke Scale and Zung Depression Scale, and disability by the Functional Independence Measure. Environmental variables in the model included marital status and receipt of rehabilitation therapy. RESULTS: Physical disability and post-stroke depressive symptoms were associated with handicap at both follow-up periods (p < 0.05). Cognitive disability and impairments from a previous stroke were also associated with handicap (p < 0.01), but only at 1 year. The presence of a spouse was found to benefit male survivors at 1 year. CONCLUSIONS: Disability and depressive symptoms restrict the meaningful life activities of stroke survivors in the first year of recovery. Social supports may be influential in reducing their impact.

Effect of blood transfusion on survival after radiotherapy as treatment for carcinoma of the prostate.

Over a 14-year period, 71 patients underwent transurethral resection of the prostate with high dose radiotherapy. Eighteen patients required perioperative transfusion. The 5-year survival in the non-transfused group was 66% and in the transfused group 17% (P less than 0.001; chi 2 = 11.57). Recurrence of tumour in the transfused group was 72% compared with 21% in the non-transfused group (P less than 0.01; chi 2 = 9.1). When Cox's models and regression analysis were used, the disease state being controlled for grade and stage, only blood transfusion was seen to influence outcome. We conclude that careful thought should be given before transfusing patients undergoing transurethral surgery for prostatic carcinoma.

Changing patterns of colorectal cancer in a regional teaching hospital.

A study was performed of all patients who underwent either surgery or endoscopic polypectomy for colorectal cancer in Oxford between 1979 and 1983 to ascertain whether any changes had occurred in presentation, diagnosis, treatment or outcome since a previous study from the same centre undertaken between 1966 and 1971. The average number of patients treated annually had increased from 52.8 to 103.4. The growth of the population of the health district was 6.7%. A similar proportion (25%) continued to present as emergencies. There was an improvement in the proportion of cases presenting with Dukes' A and B lesions (54% vs 41%) (P < 0.001), and a decrease in the number of patients with extranodal disease (from 30.4% to 13.3%) (P < 0.001). Only 13.9% of patients underwent colonoscopy before surgery and 14 patients were treated by endoscopic removal alone. In a health district with a slowly growing population, the number of patients presenting with colorectal cancer had increased dramatically over a decade. Colonoscopy has so far made little impact on making an earlier diagnosis. The increase in colorectal cancer has important implications for resource allocation.

The total parenteral nutrition service: an update.

A total parenteral nutrition (TPN) service was established in Oxford in 1978 and the results of the first 3 years were published in 1983. Since then the service has provided intravenous nutritional support to an increasing number of patients, representing a considerable and increasing financial burden on the constrained hospital budget. To assess whether this expansion is justified, and whether regular review has improved the care given to patients, a further audit has been performed for the period 1983 to 1986. Despite an increase of approximately 60% in the numbers of patients parenterally fed, line associated morbidity was less and there were no serious metabolic problems or deaths. Patient selection has improved, as judged by fewer patients fed for periods less than a week. Regular audit appears to improve the selection and treatment of patients but there remains a need to identify subgroups of patients for whom this costly form of nutrition is essential.

The use of laparoscopy in the management of right iliac fossa pain.

Fourty-six patients with a clinical diagnosis of acute appendicitis were laparoscoped before exploration. As a result the diagnosis was revised in 10 patients (22%). With experience the laparoscopic features of appendicitis can be recognised confidently so reducing the number of normal appendices removed.

Changes in quality of life over the first year after stroke: findings from the Sunnybrook Stroke Study.

PURPOSE: The purpose of this study was to investigate the longitudinal patterns of recovery of quality of life over the first year after stroke to understand the factors that are influential in this process. METHOD: A sample of 116 stroke survivors with mild to moderate impairment was followed-up at 3 months and at 1 year after stroke onset. Changes in scores on a quality of life measure were assessed in association with changes in impairment and disability over this 9-month period. The use of rehabilitation services over the first year was also documented. RESULTS: The quality of life of these survivors improved over the first year after stroke. Improvements in motor disability and depressive symptoms were found to be associated with improvements in quality of life. Additionally, survivors receiving rehabilitation therapy reported an improvement in quality of life that was independent of changes in disability and depressive symptoms. CONCLUSIONS: Opportunities to enhance the quality of life of stroke survivors exist throughout the first year of recovery. Improvements in functional ability and depression are important for long-term improvements in quality of life. Rehabilitation therapy is a potentially important resource.