Ethylene oxide review: characterization of total exposure via endogenous and exogenous pathways and their implications to risk assessment and risk management.

This review is intended to provide risk assessors and risk managers with a better understanding of issues associated with total exposures of human populations to ethylene oxide from endogenous and exogenous pathways. Biomonitoring of human populations and lab animals exposed to ethylene oxide has relied upon the detection of hemoglobin adducts such as 2-hydroxyethylvaline (HEV), which provides a useful measure of total exposure to ethylene oxide from all pathways. Recent biomonitoring data from CDC provide an excellent characterization of total exposure to ethylene oxide to the general U.S. population by demographic factors such as age, gender, and race as well as smoking habit, which might be comparable to previous measurements reported for humans and lab animals. The biochemical pathways including gastrointestinal (production by bacteria) and systemic (enzymatic production) pathways by which endogenous ethylene is generated and converted to ethylene oxide are described. The relative importance of endogenous pathways and exogenous pathways via ambient air or tobacco smoke was quantified based upon available data to characterize their relative importance to total exposure. Considerable variation was noted for HEV measurements in human populations, and important sources of variation for all pathways are discussed. Issues related to risk assessment and risk management of human populations exposed to ethylene oxide are provided within the context of characterizing total exposure, and data needs for supporting future risk assessment identified.

A genetic basis for the variable effect of smoking/nicotine on Parkinson's disease.

Prior studies have established an inverse association between cigarette smoking and the risk of developing Parkinson's disease (PD), and currently, the disease-modifying potential of the nicotine patch is being tested in clinical trials. To identify genes that interact with the effect of smoking/nicotine, we conducted genome-wide interaction studies in humans and in Drosophila. We identified SV2C, which encodes a synaptic-vesicle protein in PD-vulnerable substantia nigra (P=1 × 10(-7) for gene-smoking interaction on PD risk), and CG14691, which is predicted to encode a synaptic-vesicle protein in Drosophila (P=2 × 10(-11) for nicotine-paraquat interaction on gene expression). SV2C is biologically plausible because nicotine enhances the release of dopamine through synaptic vesicles, and PD is caused by the depletion of dopamine. Effect of smoking on PD varied by SV2C genotype from protective to neutral to harmful (P=5 × 10(-10)). Taken together, cross-validating evidence from humans and Drosophila suggests SV2C is involved in PD pathogenesis and it might be a useful marker for pharmacogenomics studies involving nicotine.

Exposures from chrysotile-containing joint compound: evaluation of new model relating respirable dust to fiber concentrations.

The potential for fiber exposure during historical use of chrysotile-containing joint compounds (JCC) has been documented, but the published data are of limited use for reconstructing exposures and assessing worker risk. Consequently, fiber concentration distributions for workers sanding JCC were independently derived by applying a recently developed model based on published dust measurements from sanding modern-day (asbestos-free) joint compound and compared to fiber concentration distributions based on limited historical measurements. This new procedure relies on factors that account for (i) differences in emission rates between modern-day and JCC and (ii) the number of fibers (quantified by phase contrast microscopy [PCM]) per mass of dust generated by sanding JCC, as determined in a bench-scale chamber study using a recreated JCC, that convert respirable dust concentrations to fiber concentrations. Airborne respirable PCM-fiber concentration medians (and 95% confidence intervals) derived for output variables using the new procedure were 0.26 (0.039, 1.7) f/cm(3) and 0.078 (0.013, 0.47) f/cm(3) , and corresponding total fiber concentrations were 1.2 (0.17, 9.2) f/cm(3) and 0.37 (0.056, 2.5) f/cm(3) , in enclosed and nonenclosed environments, respectively. Corresponding estimates of respirable and total PCM fiber concentrations measured historically during sanding of asbestos-containing joint compound-adjusted for differences between peak and time-weighted average (TWA) concentrations and documented analytical preparation and sampling artifacts-were 0.15 (0.019, 0.95) f/cm(3) and 0.86 (0.11, 5.4) f/cm(3) , respectively. The PCM-fiber concentration distributions estimated using the new procedure bound the distribution estimated from adjusted TWA historical fiber measurements, suggesting reasonable consistency of these estimates taking into account uncertainties addressed in this study.

An evidence-based approach to the 12-min consultation for a child with Down's syndrome.

BACKGROUND: Down's syndrome is the commonest genetic condition. ENT problems are common in these children and can affect their development and quality of life. METHOD: English literature review and experience of the senior author in managing ENT problems in children and adults with Down's syndrome. SEARCH STRATEGY: We carried out a Medline search on 31/03/2012 of English language publications using the following keywords: Down/Down's syndrome, hearing loss, ear infections, sleep apnoea, thyroid. RESULTS: The prevalence, presenting features and management of many common ENT conditions are significantly different in children who have Down's syndrome. This is particularly true of otitis media with effusion and sleep-disordered breathing. CONCLUSION: The outpatient consultation for a child with Down's syndrome should assess a range of specific ENT problems affecting this patient group including hearing issues, sleep-disordered breathing, recurrent upper respiratory tract infections, as well as other health conditions like hypothyroidism, atlantoaxial instability and cardiac issues, which can potentially affect the management of the patient.

Potential artifacts associated with historical preparation of joint compound samples and reported airborne asbestos concentrations.

Airborne samples collected in the 1970s for drywall workers using asbestos-containing joint compounds were likely prepared and analyzed according to National Institute of Occupational Safety and Health Method P&CAM 239, the historical precursor to current Method 7400. Experimentation with a re-created, chrysotile-containing, carbonate-based joint compound suggested that analysis following sample preparation by the historical vs. current method produces different fiber counts, likely because of an interaction between the different clearing and mounting chemicals used and the carbonate-based joint compound matrix. Differences were also observed during analysis using Method 7402, depending on whether acetic acid/dimethylformamide or acetone was used during preparation to collapse the filter. Specifically, air samples of sanded chrysotile-containing joint compound prepared by the historical method yielded fiber counts significantly greater (average of 1.7-fold, 95% confidence interval: 1.5- to 2.0-fold) than those obtained by the current method. In addition, air samples prepared by Method 7402 using acetic acid/dimethylformamide yielded fiber counts that were greater (2.8-fold, 95% confidence interval: 2.5- to 3.2-fold) than those prepared by this method using acetone. These results indicated (1) there is an interaction between Method P&CAM 239 preparation chemicals and the carbonate-based joint compound matrix that reveals fibers that were previously bound in the matrix, and (2) the same appeared to be true for Method 7402 preparation chemicals acetic acid/dimethylformamide. This difference in fiber counts is the opposite of what has been reported historically for samples of relatively pure chrysotile dusts prepared using the same chemicals. This preparation artifact should be considered when interpreting historical air samples for drywall workers prepared by Method P&CAM 239.

Bone-anchored hearing aids for people with bilateral hearing impairment: a systematic review.

BACKGROUND: Bone-anchored hearing aids (BAHAs) are indicated for people with conductive or mixed hearing loss who can benefit from amplification of sound. In resource limited health care systems, it is important that evidence regarding the benefit of BAHAs is critically appraised to aid decision-making. OBJECTIVE OF REVIEW: To assess the clinical effectiveness of BAHAs for people with bilateral hearing impairment. TYPE OF REVIEW: Systematic review. SEARCH STRATEGY: Nineteen electronic resources were searched from inception to November 2009. Additional studies were sought from reference lists, clinical experts and BAHA manufacturers. EVALUATION METHOD: Inclusion criteria were applied by two reviewers independently. Data extraction and quality assessment of full papers were undertaken by one reviewer and checked by a second. Studies were synthesised through narrative review with tabulation of results. RESULTS: Twelve studies were included. Studies suggested audiological benefits of BAHAs when compared with bone-conduction hearing aids or no aiding. A mixed pattern of results was seen when BAHAs were compared to air-conduction hearing aids. Improvements in quality of life with BAHAs were found by a hearing-specific instrument but not generic quality of life measures. Issues such as improvement of discharging ears and length of time the aid can be worn were not adequately addressed by the studies. Studies demonstrated some benefits of bilateral BAHAs. Adverse events data were limited. The quality of the studies was low. CONCLUSIONS: The available evidence is weak. As such, caution is indicated in the interpretation of presently available data. However, based on the available evidence, BAHAs appear to be a reasonable treatment option for people with bilateral conductive or mixed hearing loss. Further research into the benefits of BAHAs, including quality of life, is required to reduce the uncertainty.

Onshore-offshore patterns in the evolution of phanerozoic shelf communities.

Cluster analysis of Cambrian-Ordovician marine benthic communities and community-trophic analysis of Late Cretaceous shelf faunas indicate that major ecological innovations appeared in nearshore environments and then expanded outward across the shelf at the expense of older community types. This onshoreinnovation, offshore-archaic evolutionary pattern is surprising in light of the generally, higher species turnover rates of offshore clades. This pattern probably results from differential extinction rates of onshore as compared to offshore clades, or from differential origination rates of new ecological associations or evolutionary novelties in nearshore environments.

Tricyclic antidepressants: therapeutic properties and affinity for alpha-noradrenergic receptor binding sites in the brain.

Tricyclic antidepressants vary in their capacity to cause psychomotor activation, to relieve agitated depressive states, and to cause sedation and hypotension. We have quantified relative potencies of tricyclic antidepressants in competing for the binding of 3H-labeled WB-4101 to alpha-noradrenergic receptor sites in rat brain membranes. Affinities of tricyclic drugs for alpha-noradrenergic receptor sites in the brain correlate well with the capacity of these agents to relieve psychomotor agitation and to induce sedation and hypotension; these affinities also correlate inversely with tendencies to elicit psychomotor activation.

Sudden extinction of the dinosaurs: latest Cretaceous, upper Great Plains, USA.

Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P < 0.05) of a gradual decline of dinosaurs at the end of the Cretaceous. Stratigraphic reliability was maintained through a tripartite division of the Hell Creek, and preservational biases were corrected for by comparison of results only from similar fades as well as through the use of large-scale, statistically rigorous survey and collection procedures. The findings are in agreement with an abrupt extinction event such as one caused by an asteroid impact.

Re-creation of historical chrysotile-containing joint compounds.

Chrysotile-containing joint compound was commonly used in construction of residential and commercial buildings through the mid 1970s; however, these products have not been manufactured in the United States for more than 30 years. Little is known about actual human exposures to chrysotile fibers that may have resulted from use of chrysotile-containing joint compounds, because few exposure and no health-effects studies have been conducted specifically with these products. Because limited amounts of historical joint compounds are available (and the stability or representativeness of aged products is suspect), it is currently impossible to conduct meaningful studies to better understand the nature and magnitude of potential exposures to chrysotile that may have been associated with historical use of these products. Therefore, to support specific exposure and toxicology research activities, two types of chrysotile-containing joint compounds were produced according to original formulations from the late 1960s. To the extent possible, ingredients were the same as those used originally, with many obtained from the original suppliers. The chrysotile used historically in these products was primarily Grade 7RF9 from the Philip Carey mine. Because this mine is closed, a suitable alternate was identified by comparing the sizes and mineral composition of asbestos structures in a sample of what has been represented to be historical joint compound (all of which were chrysotile) to those in samples of three currently commercially available Grade 7 chrysotile products. The re-created materials generally conformed to original product specifications (e.g. viscosity, workability, crack resistance), indicating that these materials are sufficiently representative of the original products to support research activities.

Bone anchored hearing aids: a preliminary assessment of the impact on outpatients and cost when rehabilitating hearing in chronic suppurative otitis media.

OBJECTIVES: To compare the difference in ENT and Audiology visits, treatments dispensed and potential savings pre- and post-bone anchored hearing aid (BAHA) insertion in patients with chronic suppurative otitis media exacerbated by behind the ear hearing aids. DESIGN: A retrospective pilot study. SETTING: District General Hospital. PARTICIPANTS: All patients who had BAHA inserted from January 2001 to January 2006. PARAMETERS: Age, gender, number of visits per month, treatments per month dispensed from the ENT and Audiology Departments and direct and limited indirect medical costs pre- and post-BAHA insertion. RESULTS: Twelve of 26 (46%) adult patients had BAHA inserted over the 5-year period for CSOM. The male to female ratio was 1 : 3 with a median age of 61 (range 29-81). The number of visits and treatments dispensed per month in the ENT Department fell from a mean of 0.42-0.33 (P < 0.08) and 0.22-0.14 (P < 0.02) respectfully. When the difference in medical cost was taken into account BAHA offered a potential saving of pound 627.80 per patient. CONCLUSION: Although the initial acquisition of surgical equipment and BAHA sound processors is expensive, there is a reduction in the number of treatments and visits required for patients with chronic suppurative otitis media after BAHA is inserted leading to a reduction in average costs.

Cyproheptadine in levodopa-induced dyskinesia in parkinsonism.

The neuroendocrine properties and the beneficial effects of cyproheptadine in tardive dyskinesia led to the testing of this drug in levodopa-induced dyskinesia. Cyproheptadine administered to 6 parkinsonian patients in doses of up to 42 mg/day was of no significant benefit in either dyskinesia or symptom control. Improvement in appetite was reported by 3 patients. These observations suggested that different mechanisms may be responsible in the pathogenesis of phenothiazine and amine-induced dyskinesia. The failure to control levodopa-induced dyskinesia selectively with serotonin agonists and antagonists and the accentuation of the dyskinesia in the presence of anticholinergic agents further suggest that substances that increase directly central cholinergic activity may be effective in the control of levodopa-induced dyskinesia.

Cellular and metabolic tolerance to an opioid narcotic in mouse brain.

1. Running activity and brain levorphanol concentration were measured in nontolerant and tolerant mice given various doses of (3)H-levorphanol.2. The principal factor responsible for tolerance in the mouse is a loss of sensitivity to the narcotic drug at the cellular level in brain; despite adequate brain concentrations, the pharmacological effects are diminished or absent.3. There is also metabolic tolerance; a given dose establishes a lower brain concentration in tolerant than in non-tolerant animals.4. The two kinds of tolerance are distinguished here and the contribution of each is assessed.

Pancreatic pathology in pentamidine-induced diabetes in acquired immunodeficiency syndrome patients.

An acquired immunodeficiency syndrome patient who was treated with pentamidine for a pneumocystis infection developed hypoglycemia followed by diabetes mellitus. The pathologic findings in the pancreas consisted of a significant decrease in the number of insulin-positive cells as measured by immunoperoxidase techniques when compared with comparable tissue from an age- and sex-matched control. There was also a decrease in the staining intensity of the insulin-positive cells, an absolute increase in the glucagon-positive cells, and no significant change in the number of somatostatin-positive cells. Routinely stained histologic sections showed morphologic changes in the islets with features different from those described in insulin-dependent diabetes mellitus or those caused by the toxin Vacor. The islets had increased vascular spaces, no islet cell necrosis, no fibrosis, and no lymphocytic infiltrates when compared with an age-matched control.

Role of the feedback signal in electromyograph biofeedback: the relevance of attention.

This article describes two experiments designed to examine the hypothesis that the critical role of the feedback signal in frontalis electromyograph (EMG) biofeedback is an attentional one. In both experiments, high- and low-absorption subjects were assigned to either a biofeedback condition, a no-feedback condition, or an attentional demand condition in which external stimuli, related to relaxation, were presented as an attentional focus. The two experiments differed essentially in the type of attentional demand condition that was employed and varied the compelling nature of the demand on subjects for an external attentional focus. The pattern of results was consistent with the attentional hypothesis. For low-absorption subjects, performance in the biofeedback and attentional demand conditions was equivalent and appreciably greater than in the no-feedback condition. For high-absorption subjects, an interference effect of biofeedback was observed, but data indicated a similar interference effect on the performance of subjects when the attentional demand condition was most compelling. The pattern of results obtained point to the special relevance of attentional processes and highlight their lack of emphasis in contemporary theoretical models of EMG biofeedback.