Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-30 (of 47 Records) |
Query Trace: Hammer M[original query] |
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Exposure to emissions generated by 3-dimensional printing with polycarbonate: effects on peripheral vascular function, cardiac vascular morphology and expression of markers of oxidative stress in male rat cardiac tissue
Krajnak K , Farcas M , Richardson D , Hammer MA , Waugh S , McKinney W , Knepp A , Jackson M , Burns D , LeBouf R , Matheson J , Thomas T , Qian Y . J Toxicol Environ Health A 2024 1-19 Three-dimensional (3D) printing with polycarbonate (PC) plastic occurs in manufacturing settings, homes, and schools. Emissions generated during printing with PC stock and bisphenol-A (BPA), an endocrine disrupter in PC, may induce adverse health effects. Inhalation of 3D printer emissions, and changes in endocrine function may lead to cardiovascular dysfunction. The goal of this study was to determine whether there were any changes in markers of peripheral or cardiovascular dysfunction in animals exposed to PC-emissions. Male Sprague Dawley rats were exposed to PC-emissions generated by 3D printing for 1, 4, 8, 15 or 30 d. Exposure induced a reduction in the expression of the antioxidant catalase (Cat) and endothelial nitric oxide synthase (eNos). Endothelin and hypoxia-induced factor 1α transcripts increased after 30 d. Alterations in transcription were associated with elevations in immunostaining for estrogen and androgen receptors, nitrotyrosine, and vascular endothelial growth factor in cardiac arteries of PC-emission exposed animals. There was also a reduction eNOS immunostaining in cardiac arteries from rats exposed to PC-emissions. Histological analyses of heart sections revealed that exposure to PC-emissions resulted in vasoconstriction of cardiac arteries and thickening of the vascular smooth muscle wall, suggesting there was a prolonged vasoconstriction. These findings are consistent with studies showing that inhalation 3D-printer emissions affect cardiovascular function. Although BPA levels in animals were relatively low, exposure-induced changes in immunostaining for estrogen and androgen receptors in cardiac arteries suggest that changes in the action of steroid hormones may have contributed to the alterations in morphology and markers of cardiac function. |
Noise exposure and hearing loss among workers at a hammer forge company
Brueck SE , Eisenberg J , Zechmann EL , Murphy WJ , Krieg E , Morata TC . Semin Hear 2023 44 (4) 485-502 The National Institute for Occupational Safety and Health (NIOSH) evaluated continuous and impact noise exposures and hearing loss among workers at a hammer forge company. Full-shift personal noise exposure measurements were collected on forge workers across 15 different job titles; impact noise characteristics and one-third octave band noise levels were assessed at the forge hammers; and 4,750 historic audiometric test records for 483 workers were evaluated for hearing loss trends. Nearly all workers' noise exposures exceeded regulatory and/or recommended exposure limits. Workers working in jobs at or near the hammers had full-shift time-weighted average noise exposures above 100 decibels, A-weighted. Impact noise at the hammers reached up to 148 decibels. Analysis of audiometric test records showed that 82% of workers had experienced a significant threshold shift, as defined by NIOSH, and 63% had experienced a standard threshold shift, as defined by the Occupational Safety and Health Administration (OSHA). All workers with an OSHA standard threshold shift had a preceding NIOSH significant threshold shift which occurred, on average, about 7 years prior. This evaluation highlights forge workers' exposures to high levels of noise, including impact noise, and how their hearing worsened with age and length of employment. © 2023. Thieme. All rights reserved. Thieme Medical Publishers, Inc. |
Inhalation of polycarbonate emissions generated during 3D printing processes affects neuroendocrine function in male rats
Krajnak K , Farcas M , McKinney W , Waugh S , Mandler K , Knepp A , Jackson M , Richardson D , Hammer M , Matheson J , Thomas T , Qian Y . J Toxicol Environ Health A 2023 86 (16) 1-22 Three-dimensional (3D) printing of manufactured goods has increased in the last 10 years. The increased use of this technology has resulted in questions regarding the influence of inhaling emissions generated during printing. The goal of this study was to determine if inhalation of particulate and/or toxic chemicals generated during printing with polycarbonate (PC) plastic affected the neuroendocrine system. Male rats were exposed to 3D-printer emissions (592 µg particulate/m(3) air) or filtered air for 4 h/day (d), 4 days/week and total exposures lengths were 1, 4, 8, 15 or 30 days. The effects of these exposures on hormone concentrations, and markers of function and/or injury in the olfactory bulb, hypothalamus and testes were measured after 1, 8 and 30 days exposure. Thirty days of exposure to 3D printer emissions resulted in reductions in thyroid stimulating hormone, follicle stimulating hormone and prolactin. These changes were accompanied by (1) elevation in markers of cell injury; (2) reductions in active mitochondria in the olfactory bulb, diminished gonadotropin releasing hormone cells and fibers as well as less tyrosine hydroxylase immunolabeled fibers in the arcuate nucleus; and (3) decrease in spermatogonium. Polycarbonate plastics may contain bisphenol A, and the effects of exposure to these 3D printer-generated emissions on neuroendocrine function are similar to those noted following exposure to bisphenol A. |
Evaluation of pulmonary effects of 3-D printer emissions from acrylonitrile butadiene styrene using an air-liquid interface model of primary normal human-derived bronchial epithelial cells
Farcas MT , McKinney W , Coyle J , Orandle M , Mandler WK , Stefaniak AB , Bowers L , Battelli L , Richardson D , Hammer MA , Friend SA , Service S , Kashon M , Qi C , Hammond DR , Thomas TA , Matheson J , Qian Y . Int J Toxicol 2022 41 (4) 10915818221093605 This study investigated the inhalation toxicity of the emissions from 3-D printing with acrylonitrile butadiene styrene (ABS) filament using an air-liquid interface (ALI) in vitro model. Primary normal human-derived bronchial epithelial cells (NHBEs) were exposed to ABS filament emissions in an ALI for 4 hours. The mean and mode diameters of ABS emitted particles in the medium were 175 ± 24 and 153 ± 15 nm, respectively. The average particle deposition per surface area of the epithelium was 2.29 × 10(7) ± 1.47 × 10(7) particle/cm(2), equivalent to an estimated average particle mass of 0.144 ± 0.042 μg/cm(2). Results showed exposure of NHBEs to ABS emissions did not significantly affect epithelium integrity, ciliation, mucus production, nor induce cytotoxicity. At 24 hours after the exposure, significant increases in the pro-inflammatory markers IL-12p70, IL-13, IL-15, IFN-γ, TNF-α, IL-17A, VEGF, MCP-1, and MIP-1α were noted in the basolateral cell culture medium of ABS-exposed cells compared to non-exposed chamber control cells. Results obtained from this study correspond with those from our previous in vivo studies, indicating that the increase in inflammatory mediators occur without associated membrane damage. The combination of the exposure chamber and the ALI-based model is promising for assessing 3-D printer emission-induced toxicity. |
Comfortable SCBA weights from biomechanical models for firefighting tasks
Xu S , Hu M , Powell J , Zhuang Z . Advances in Simulation and Digital Human Modeling AHFE 2021 Lecture Notes in Networks and Systems 2021 264 231-238 Firefighters are required to use a self-contained breathing apparatus (SCBA) for respiratory protection when engaged in a variety of firefighting duties. While the SCBA provides crucial respiratory support and protection, it is also cumbersome and heavy. Questions have arisen to address the current weight limitation listed in 42 CFR Part 84, which mandates the maximum weight of 16 kg (35.2 lbs) for an SCBA system. The objective of the overarching study is to inform a maximum comfortable SCBA weight by developing static and dynamic biomechanical models and collecting physiological burden and postural stability data to evaluate stressors for firefighting tasks. This paper presents data from the static models. Eight representative firefighting tasks (stair climb, hose carry, weighted carry, rope pull, dummy drag, hammer slam, overhaul, and hose advance) were used in the biomechanical models. Maximum comfortable SCBA weights were calculated based on three biomechanical models (abdominal extension/tension, lateral extension/tension, and abdominal rotation). This study found that the maximum comfortable weight for an SCBA was 39 lbs for the static postures of interest. Further studies with human subjects to investigate the SCBA weight limit by using physiological burden and dynamic models are underway and will provide crucial data to inform updates to the current weight limits for SCBAs allowing more features and extended durations of these devices without compromising user safety, performance, or comfort. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG. |
Incident bone fracture and mortality in a large HIV cohort outpatient study, 2000-2017, USA
Battalora L , Armon C , Palella F , Li J , Overton ET , Hammer J , Fuhrer J , Novak RM , Carlson K , Spear JR , Buchacz K . Arch Osteoporos 2021 16 (1) 117 We evaluated the association of bone fracture with mortality among persons with HIV, controlling for sociodemographic, behavioral, and clinical factors. Incident fracture was associated with 48% greater risk of all-cause mortality, underscoring the need for bone mineral density screening and fracture prevention. PURPOSE/INTRODUCTION: Low bone mineral density (BMD) and fracture are more common among persons with HIV (PWH) than those without HIV infection. We evaluated the association of bone fracture with mortality among PWH, controlling for sociodemographic, behavioral, and clinical factors. METHODS: We analyzed data from HIV Outpatient Study (HOPS) participants seen at nine US HIV clinics during January 1, 2000, through September 30, 2017. Incident fracture rates and post-fracture mortality were compared across four calendar periods. Cox proportional hazards analyses determined factors associated with all-cause mortality among all participants and those with incident fracture. RESULTS: Among 6763 HOPS participants, 504 (7.5%) had incident fracture (median age = 47 years) and 719 (10.6%) died. Of fractures, 135 (26.8%) were major osteoporotic (hip/pelvis, wrist, spine, arm/shoulder). During observation, 27 participants with major osteoporotic fractures died (crude mortality 2.97/100 person-years [PY]), and 48 with other site fractures died (crude mortality 2.51/100 PY). Post-fracture, age- and sex-adjusted all-cause mortality rates per 100 PY decreased from 8.5 during 2000-2004 to 1.9 during 2013-2017 (P<0.001 for trend). In multivariable analysis, incident fracture was significantly associated with all-cause mortality (Hazard Ratio 1.48, 95% confidence interval 1.15-1.91). Among 504 participants followed post-fracture, pulmonary, kidney, and cardiovascular disease, hepatitis C virus co-infection, and non-AIDS cancer, remained independently associated with all-cause mortality. CONCLUSIONS: Incident fracture was associated with 48% greater risk of all-cause mortality among US PWH in care, underscoring the need for BMD screening and fracture prevention. Although fracture rates among PWH increased during follow-up, post-fracture death rates decreased, likely reflecting advances in HIV care. |
Physicochemical characterization and genotoxicity of the broad class of carbon nanotubes and nanofibers used or produced in U.S. facilities.
Fraser K , Kodali V , Yanamala N , Birch ME , Cena L , Casuccio G , Bunker K , Lersch TL , Evans DE , Stefaniak A , Hammer MA , Kashon ML , Boots T , Eye T , Hubczak J , Friend SA , Dahm M , Schubauer-Berigan MK , Siegrist K , Lowry D , Bauer AK , Sargent LM , Erdely A . Part Fibre Toxicol 2020 17 (1) 62 BACKGROUND: Carbon nanotubes and nanofibers (CNT/F) have known toxicity but simultaneous comparative studies of the broad material class, especially those with a larger diameter, with computational analyses linking toxicity to their fundamental material characteristics was lacking. It was unclear if all CNT/F confer similar toxicity, in particular, genotoxicity. Nine CNT/F (MW #1-7 and CNF #1-2), commonly found in exposure assessment studies of U.S. facilities, were evaluated with reported diameters ranging from 6 to 150 nm. All materials were extensively characterized to include distributions of physical dimensions and prevalence of bundled agglomerates. Human bronchial epithelial cells were exposed to the nine CNT/F (0-24 μg/ml) to determine cell viability, inflammation, cellular oxidative stress, micronuclei formation, and DNA double-strand breakage. Computational modeling was used to understand various permutations of physicochemical characteristics and toxicity outcomes. RESULTS: Analyses of the CNT/F physicochemical characteristics illustrate that using detailed distributions of physical dimensions provided a more consistent grouping of CNT/F compared to using particle dimension means alone. In fact, analysis of binning of nominal tube physical dimensions alone produced a similar grouping as all characterization parameters together. All materials induced epithelial cell toxicity and micronuclei formation within the dose range tested. Cellular oxidative stress, DNA double strand breaks, and micronuclei formation consistently clustered together and with larger physical CNT/F dimensions and agglomerate characteristics but were distinct from inflammatory protein changes. Larger nominal tube diameters, greater lengths, and bundled agglomerate characteristics were associated with greater severity of effect. The portion of tubes with greater nominal length and larger diameters within a sample was not the majority in number, meaning a smaller percentage of tubes with these characteristics was sufficient to increase toxicity. Many of the traditional physicochemical characteristics including surface area, density, impurities, and dustiness did not cluster with the toxicity outcomes. CONCLUSION: Distributions of physical dimensions provided more consistent grouping of CNT/F with respect to toxicity outcomes compared to means only. All CNT/F induced some level of genotoxicity in human epithelial cells. The severity of toxicity was dependent on the sample containing a proportion of tubes with greater nominal lengths and diameters. |
Outbreak of norovirus illness among wildfire evacuation shelter populations - Butte and Glenn Counties, California, November 2018
Karmarkar E , Jain S , Higa J , Fontenot J , Bertolucci R , Huynh T , Hammer G , Brodkin A , Thao M , Brousseau B , Hopkins D , Kelly E , Sheffield M , Henley S , Whittaker H , Herrick RL , Pan CY , Chen A , Kim J , Schaumleffel L , Khwaja Z , Epson E , Chai SJ , Wadford D , Vugia D , Lewis L . MMWR Morb Mortal Wkly Rep 2020 69 (20) 613-617 The Camp Fire, California's deadliest wildfire, began November 8, 2018, and was extinguished November 25 (1). Approximately 1,100 evacuees from the fire sought emergency shelter. On November 10, acute gastroenteritis (AGE) was reported in two evacuation shelters; norovirus illness was suspected, because it is commonly detected in shelter-associated AGE outbreaks. Norovirus is highly contagious and resistant to several disinfectants. Butte County Public Health Department (BCPHD), assisted by the California Department of Public Health (CDPH), initiated active surveillance to identify cases, confirm the etiology, and assess shelter infection prevention and control (IPC) practices to guide recommendations. During November 8-30, a total of 292 patients with AGE were identified among nine evacuation shelters; norovirus was detected in 16 of 17 unique patient stool specimens. Shelter IPC assessments revealed gaps in illness surveillance, isolation practices, cleaning, disinfection, and handwashing. CDPH and BCPHD collaborated with partner agencies to implement AGE screening, institute isolation protocols and 24-hour cleaning services, and promote proper hand hygiene. During disasters with limited resources, damaged infrastructure, and involvement of multiple organizations, establishing shelter disease surveillance and IPC is difficult. However, prioritizing effective surveillance and IPC at shelter activation is necessary to prevent, identify, and contain outbreaks. |
Education and training to build capacity in Total Worker Health(R): Proposed competencies for an emerging field
Newman LS , Scott JG , Childress A , Linnan L , Newhall WJ , McLellan DL , Campo S , Freewynn S , Hammer LB , Leff M , Macy G , Maples EH , Rogers B , Rohlman DS , Tenney L , Watkins C . J Occup Environ Med 2020 62 (8) e384-e391 OBJECTIVE: Establishment of core competencies for education and training of professionals entering the emerging field of Total Worker Health(R). METHODS: Compilation and distillation of information obtained over a five-year period from Total Worker Health symposia, workshops, and academic offerings, plus contributions from key stakeholders regarding education and training needs. RESULTS: A proposed set of Total Worker Health competencies aligns under six broad domains: Subject Matter Expertise; Advocacy and Engagement; Program Planning, Implementation and Evaluation; Communications and Dissemination; Leadership and Management; and Partnership Building and Coordination. CONCLUSIONS: Proposed set of core competencies will help standardize education and training for professionals being trained in Total Worker Health. It serves as an invitation for further input from stakeholders in academia, business, labor, and government. |
Lower serum adiponectin level is associated with lipodystrophy among HIV-infected men in the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (SUN) study
Klos B , Patel P , Rose C , Bush T , Conley L , Kojic EM , Henry K , Brooks JT , Hammer J . HIV Med 2019 20 (8) 534-541 OBJECTIVES: Adiponectin levels are inversely related to cardiovascular risk and are low in diabetics and obese persons. We examined the association between adiponectin concentration and HIV-associated lipodystrophy, which remains unclear. METHODS: The Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (SUN) was a prospective cohort study of HIV-infected adults conducted in four US cities. Lean body and fat masses were assessed using dual-energy X-ray absorptiometry scans. Using baseline data from 2004 to 2006, we defined lipodystrophy using a sex-specific fat mass ratio and performed cross-sectional analyses of associated risks using multivariable logistic regression. RESULTS: Among 440 male participants (median age 42 years; 68% non-Hispanic white; 88% prescribed combination antiretroviral therapy; median CD4 lymphocyte count 468 cells/muL; 76% with viral load < 400 HIV-1 RNA copies/mL; 5% diabetic; median body mass index 25 kg/m(2) ), median concentrations of leptin and adiponectin were 3.04 ng/L [interquartile range (IQR) 1.77-5.43 ng/L] and 8005 mug/mL (IQR 4950-11 935 mug/mL), respectively. The prevalence of lipodystrophy was 14%. Lipodystrophy was significantly associated with increasing age [prevalence ratio (PR) 1.50; 95% confidence interval (CI) 1.10-2.06, per 10 years], adiponectin < 8005 mug/mL (PR 5.02; 95% CI 2.53-9.95), ever stavudine use (PR 2.26; 95% CI 1.36-3.75), CD4 cell count > 500 cells/muL (PR 2.59; 95% CI 1.46-4.61), viral load < 400 copies/mL (PR 3.98; 95% CI 1.25-12.6), highly sensitive C-reactive protein < 1.61 mg/L (PR 1.91; 95% CI 1.11-3.28) and smoking (PR 0.42; 95% CI 0.22-0.78). CONCLUSIONS: Among men in this HIV-infected cohort, the prevalence of lipodystrophy was similar to previous estimates for persons living with HIV, and was associated with lower adiponectin levels, potentially indicating increased cardiovascular disease risk. |
The effects of feed force on rivet bucking bar vibrations
McDowell TW , Xu XS , Warren C , Welcome DE , Dong RG . Int J Ind Ergon 2018 67 145-158 Percussive riveting is the primary process for attaching the outer sheet metal “skins” of an aircraft to its airframe. Workers using manually-operated riveting tools (riveting hammers and rivet bucking bars) are exposed to significant levels of hand-transmitted vibration (HTV) and are at risk of developing components of hand-arm vibration syndrome (HAVS). To protect workers, employers can assess and select riveting tools that produce reduced HTV exposures. Researchers at the National Institute for Occupational Safety & Health (NIOSH) have developed a laboratory-based apparatus and methodology to evaluate the vibrations of rivet bucking bars. Using this simulated riveting approach, this study investigated the effects of feed force on the vibrations of several typical rivet bucking bars and that transmitted to the bucking bar operator's wrist. Five bucking bar models were assessed under three levels of feed force. The study results demonstrate that the feed force can be a major influencing factor on bucking bar vibrations. Similar feed force effects were observed at the bucking bar operator's wrist. This study also shows that different bucking bar designs will respond differently to variations in feed force. Some bucking bar designs may offer reduced vibration exposures to the bar operator's fingers while providing little attenuation of wrist acceleration. Knowledge of how rivet bucking bar models respond to riveting hammer vibrations can be important for making informed bucking bar selections. The study results indicate that, to help in the appropriate selection of bucking bars, candidate bar models should be evaluated at multiple feed force levels. The results also indicate that the bucking bar model, feed force level, or the bucking bar operator have no meaningful effects on the vibration excitation (riveting hammer), which further suggests that the test apparatus proposed by NIOSH researchers meets the basic requirements for a stable vibration source in laboratory-based bucking bar vibration assessments. This study provides relevant information that can be used to help develop a standardized laboratory-based bucking bar evaluation methodology and to help in the selection of appropriate bucking bars for various workplace riveting applications. Relevance to Industry: Because the feed force level can affect HTV exposures to bucking bar operators, the feed force required for specific riveting operations should be an important consideration when selecting bucking bar models. This study provides useful information about bucking bar responses to riveting hammer vibrations; this knowledge can improve bucking bar selections. |
Prevalence and incidence of anal and cervical high-risk human papillomavirus (HPV) types covered by current HPV vaccines among HIV-infected women in the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (The SUN Study)
Kojic EM , Conley L , Bush T , Cu-Uvin S , Unger ER , Henry K , Hammer J , Escota G , Darragh TM , Palefsky JM , Brooks JT , Patel P . J Infect Dis 2018 217 (10) 1544-1552 Background: Nonavalent (9v) human papilloma virus vaccine targets high-risk (HR)-HPV types 16, 18, 31, 33, 45, 52, 58, and low-risk 6, 11. We examined prevalence, incidence, and clearance of anal and cervical HR-HPV in HIV-infected women. Methods: From 2004-2006, the SUN Study enrolled 167 women from four US cities. Anal and cervical specimens were collected annually for cytology and identification of 37 HPV types; 14 HR include: 9v 16, 18, 31, 33, 45, 52, 58; non-9v 35, 39, 51, 56, 59, 66, 68. Results: Baseline characteristics of 126 women included: median age 38 years; 57% non-Hispanic black; 67% HIV RNA < 400 copies/mL; 90% CD4 counts >/= 200 cells/mm3. HPV prevalence at anus and cervix was 90% and 83%; for 9v HR-HPV types, 67% and 51%; non-9v HR-HPV, 54% and 29%, respectively. 9v and non-9v HR-HPV incidence rates/100 person-years were similar (10.4 vs 9.5: 8.5 vs 8.3, respectively); 9v clearance rates were 42% and 61%; non-9v 46% and 59%, in anus and cervix, respectively. Conclusions: Anal HR-HPV prevalence was higher than cervical with lower clearance; incidence was similar. Although prevalence of non-9v HR-HPV was substantial, 9v HR-HPV types were generally more prevalent. These findings support use of nonavalent vaccine in HIV-infected women. |
Prevalence, incidence, and clearance of anal high-risk human papillomavirus infection among HIV-infected men in the SUN Study
Patel P , Bush T , Kojic EM , Conley L , Unger ER , Darragh TM , Henry K , Hammer J , Escota G , Palefsky JM , Brooks JT . J Infect Dis 2017 217 (6) 953-963 Background: The natural history of anal HPV infection among HIV-infected men is unknown. Methods: We collected anal swabs for cytology, HPV detection, and genotyping at annual visits from 2004-2012. We examined baseline prevalence, incidence and clearance of anal HPV infection at 48 months, and associated factors among HIV-infected men. Results: We examined 403 men who have sex with men (MSM) and 96 men who have sex with women (MSW) (median age 42 years for both, 87 vs. 91% were prescribed cART, median CD4 cell count was 454 vs. 379 cells/mm3, and 74 vs. 75% had undetectable viral load, respectively). For type 16, prevalence among MSM and MSW was 38% vs. 14% (p<0.001), and incidence was 24% vs. 6% (p=0.001), respectively. For type 18, prevalence was 24% vs. 8% (p<0.001), and incidence was 14% vs. 3% (p=0.009), respectively. Among MSM and MSW, clearance of prevalent HPV 16 and HPV 18 was 51% and 66% (p=0.682), and 69% and 60% (p=0.538), respectively. Condomless receptive anal sex was associated with persistent HPV 16 among all men (OR 2.37, p=0.014). Conclusions: MSM had higher prevalence and incidence of HPV than MSW, but similar clearance. Condomless anal sex may predict cancer risk among HIV-infected men. |
Antiretroviral nonadherence and condomless sex in the HIV Outpatient Study, USA, 2007-2014
Durham MD , Hart R , Buchacz K , Hammer J , Young B , Yang D , Wood K , Yangco B , Brooks JT . Int J STD AIDS 2017 29 (2) 956462417720547 Effective antiretroviral therapy (ART) reduces plasma HIV RNA viral load (VL) to undetectable levels and its effectiveness depends on consistent adherence. Consistent adherence and use of safe sex practices may substantially decrease the risk of HIV transmission. We sought to explore the potential association between self-reported nonadherence to ART and engaging in unsafe sexual practices capable of transmitting HIV. Using clinical and audio computer-assisted self-interview data from the prospective HIV Outpatient Study from 2007 to 2014, we assessed the frequency of self-reported ART nonadherence during the three days prior to the survey among HIV-infected persons in care and factors associated with self-reported ART nonadherence. Of 1729 patients included in this analysis (median age = 48 years, 74.3% men who have sex with men), 17% were nonadherent, 15% had a detectable VL, and 42% reported condomless anal or vaginal sex in the past six months. In multivariable analysis, self-reported nonadherence was independently associated with younger age (adjusted odds ratio [aOR] 0.8 per additional ten years, [95% CI] 0.7-1.0), non-Hispanic black race/ethnicity (aOR 1.9; 95% CI 1.4-2.6 versus white), public health insurance (aOR 1.6, 95% CI 1.2-2.3 compared with private), survey date in 2011-2014 versus 2007-2010 (aOR 0.7, 95% CI 0.5-0.9), CD4 cell count ≥ 500 versus < 200 cells/mm3 (aOR 0.3, 95% CI 0.2-0.5), greater number of ART regimen doses (aOR 1.6, 95% CI 1.3-2.2), and binge drinking (aOR 1.4, 95% CI, 1.1-1.9). In this analysis, self-reported nonadherence was not associated with engaging in condomless sex. |
Vitamin D deficiency is associated with IL-6 levels and monocyte activation in HIV-infected persons
Manion M , Hullsiek KH , Wilson EMP , Rhame F , Kojic E , Gibson D , Hammer J , Patel P , Brooks JT , Baker JV , Sereti I . PLoS One 2017 12 (5) e0175517 BACKGROUND: Immune activation plays a key role in HIV pathogenesis. Markers of inflammation have been associated with vitamin D deficiency in the general population. Studies have also demonstrated associations of vitamin D deficiency with increased risk of HIV progression and death. The relationship between persistent inflammation and immune activation during chronic HIV infection and vitamin D deficiency remains unclear. METHODS: Cryopreserved specimens were analyzed from 663 participants at the time of enrollment from the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy (SUN Study) from 2004 to 2006. Biomarkers of inflammation, atherosclerosis, and coagulation were measured using enzyme-linked immunosorbent assays (ELISAs) and electrochemiluminescence. 25(OH)D, the stable precursor form of vitamin D, was measured using a radioimmunoassay with levels defined as: normal (≥30ng/mL), insufficient (20-29 ng/mL) and deficient (<20 ng/mL). Monocyte phenotypes were assessed by flow cytometry. Linear and logistic regression models were used to determine statistical associations between biomarkers and vitamin D deficiency. RESULTS: 25(OH)D levels were deficient in 251 (38%) participants, insufficient in 222 (34%), and normal in 190 (29%). Patients with vitamin D deficiency, when compared to those with insufficient or normal vitamin D levels, had increased levels of IL-6 (23%; p<0.01), TNF-alpha (21%, p = 0.03), D-dimer (24%, p = 0.01), higher proportions of CD14dimCD16+ (22%, p<0.01) and CX3CR1+ monocytes (48%; p<0.001) and decreased frequency of CCR2+ monocytes (-3.4%, p<0.001). In fully adjusted models, vitamin D associations with abnormal biomarker levels persisted for IL-6 levels and CX3CR1+ and CCR2+ phenotypes. CONCLUSIONS: Vitamin D deficiency is associated with greater inflammation and activated monocyte phenotypes. The role of vitamin D deficiency in persistent immune activation and associated complications during chronic HIV disease should be further evaluated as a possible target for intervention. |
Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration
Welcome DE , Dong RG , Xu XS , Warren C , McDowell TW . Occup Ergon 2016 13 (1) 23-44 BACKGROUND: Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. OBJECTIVE: The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools. METHODS: A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations. RESULTS: When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it. CONCLUSIONS: This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for better effectiveness for protecting the fingers. |
Direct and indirect effects of heavy alcohol use on clinical outcomes in a longitudinal study of HIV patients on ART
Kahler CW , Liu T , Cioe PA , Bryant V , Pinkston MM , Kojic EM , Onen N , Baker JV , Hammer J , Brooks JT , Patel P . AIDS Behav 2016 21 (7) 1825-1835 In a cohort of patients receiving care for HIV, we examined longitudinally the impact of past 30-day frequency of heavy drinking (consuming 5+ drinks on one occasion) on HIV-related (detectable viral load and CD4+ T cell count) and non-HIV-related (hemoglobin and biomarkers of kidney function and liver fibrosis) clinical outcomes and the extent to which these effects were due to reduced antiretroviral therapy (ART) adherence. Data came from the Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy. Between March 2004 and June 2006, 533 individuals receiving ART were recruited and followed every 6 months for six years. Using longitudinal mediation analysis, we estimated natural direct effects (NDE) of heavy drinking frequency (never, 1-3 times, or 4+ times in the past 30 days) on clinical outcomes and natural indirect effects (NIE) mediated via ART adherence. A one-level increase in heavy drinking frequency had a significant negative NDE on CD4+ T-cell counts (-10.61 cells/mm3; 95 % CI [-17.10, -4.12]) and a significant NIE through reduced ART adherence of -0.72 cells/mm3 (95 % CI [-1.28, -0.15]), as well as a significant NIE on risk of detectable viral load (risk ratio = 1.03; 95 % CI [1.00, 1.05]). Heavy drinking had a significant detrimental NIE on a combined index of 5-year mortality risk and detrimental NDE and total effect on a biomarker of liver fibrosis. Heavy drinking has deleterious effects on multiple clinical outcomes in people living with HIV, some of which are mediated through reduced ART adherence. |
Comparison of cell counting methods in rodent pulmonary toxicity studies: automated and manual protocols and considerations for experimental design
Zeidler-Erdely PC , Antonini JM , Meighan TG , Young SH , Eye TJ , Hammer MA , Erdely A . Inhal Toxicol 2016 28 (9) 1-11 Pulmonary toxicity studies often use bronchoalveolar lavage (BAL) to investigate potential adverse lung responses to a particulate exposure. The BAL cellular fraction is counted, using automated (i.e. Coulter Counter(R)), flow cytometry or manual (i.e. hemocytometer) methods, to determine inflammatory cell influx. The goal of the study was to compare the different counting methods to determine which is optimal for examining BAL cell influx after exposure by inhalation or intratracheal instillation (ITI) to different particles with varying inherent pulmonary toxicities in both rat and mouse models. General findings indicate that total BAL cell counts using the automated and manual methods tended to agree after inhalation or ITI exposure to particle samples that are relatively nontoxic or at later time points after exposure to a pneumotoxic particle when the response resolves. However, when the initial lung inflammation and cytotoxicity was high after exposure to a pneumotoxic particle, significant differences were observed when comparing cell counts from the automated, flow cytometry and manual methods. When using total BAL cell count for differential calculations from the automated method, depending on the cell diameter size range cutoff, the data suggest that the number of lung polymorphonuclear leukocytes (PMN) varies. Importantly, the automated counts, regardless of the size cutoff, still indicated a greater number of total lung PMN when compared with the manual method, which agreed more closely with flow cytometry. The results suggest that either the manual method or flow cytometry would be better suited for BAL studies where cytotoxicity is an unknown variable. |
Low bone mineral density and risk of incident fracture in HIV-infected adults
Battalora L , Buchacz K , Armon C , Overton ET , Hammer J , Patel P , Chmiel JS , Wood K , Bush TJ , Spear JR , Brooks JT , Young B . Antivir Ther 2016 21 (1) 45-54 BACKGROUND: Prevalence rates of low bone mineral density (BMD) and bone fractures are higher among HIV-infected adults compared with the general United States (US) population, but the relationship between BMD and incident fractures in HIV-infected persons has not been well described. METHODS: Dual energy X-ray absorptiometry (DXA) results of the femoral neck of the hip and clinical data were obtained prospectively during 2004-2012 from participants in two HIV cohort studies. Low BMD was defined by a T-score in the interval >-2.5 to <-1.0 (osteopenia) or ≤-2.5 (osteoporosis). We analysed the association of low BMD with risk of subsequent incident fractures, adjusted for sociodemographics, other risk factors and covariables, using multivariable proportional hazards regression. RESULTS: Among 1,006 participants analysed (median age 43 years [IQR 36-49], 83% male, 67% non-Hispanic white, median CD4(+) T-cell count 461 cells/mm(3) [IQR 311-658]), 36% (n=358) had osteopenia and 4% (n=37) osteoporosis; 67 had a prior fracture documented. During 4,068 person-years of observation after DXA scanning, 85 incident fractures occurred, predominantly rib/sternum (n=18), hand (n=14), foot (n=13) and wrist (n=11). In multivariable analyses, osteoporosis (adjusted hazard ratio [aHR] 4.02, 95% CI 2.02, 8.01) and current/prior tobacco use (aHR 1.59, 95% CI 1.02, 2.50) were associated with incident fracture. CONCLUSIONS: In this large sample of HIV-infected adults in the US, low baseline BMD was significantly associated with elevated risk of incident fracture. There is potential value of DXA screening in this population. |
Diversity of clinical and environmental isolates of Vibrio cholerae in natural transformation and contact-dependent bacterial killing indicative of type VI secretion system activity
Bernardy EE , Turnsek MA , Wilson SK , Tarr CL , Hammer BK . Appl Environ Microbiol 2016 82 (9) 2833-2842 The bacterial pathogen Vibrio cholerae can occupy both the human gut and aquatic reservoirs, where it may colonize chitinous surfaces that induce expression of factors for three phenotypes: chitin utilization, DNA uptake by natural transformation, and constitutive contact-dependent bacterial killing indicative of the Type VI secretion system (T6SS). In this study, we surveyed a diverse set of 53 isolates from different geographic locales collected over the past century from human clinical and environmental specimens for each phenotype outlined above. The set included pandemic isolates of serogroup O1, as well as several serogroup O139 and non-O1/non-O139 strains. We found that while chitin utilization was common, only 22.6% of all isolates tested were proficient at chitin-induced natural transformation, suggesting that transformation is expendable. Constitutive contact-dependent killing of Escherichia coli prey, which is indicative of a functional T6SS, was rare among clinical isolates (only 4 of 29) but common among environmental isolates (22 of 24). These results bolster the pathoadaptive model that tight regulation of T6SS-mediated bacterial killing is beneficial in a human host, whereas, constitutive killing by environmental isolates may give a competitive advantage in natural settings. Future sequence analysis of this set of diverse isolates may identify previously unknown regulators and structural components for both natural transformation and T6SS. |
Intervention effects on safety compliance and citizenship behaviors: Evidence from the Work, Family, And Health Study
Hammer LB , Johnson RC , Crain TL , Bodner T , Kossek EE , Davis KD , Kelly EL , Buxton OM , Karuntzos G , Chosewood LC , Berkman L . J Appl Psychol 2016 101 (2) 190-208 We tested the effects of a work-family intervention on employee reports of safety compliance and organizational citizenship behaviors in 30 health care facilities using a group-randomized trial. Based on conservation of resources theory and the work-home resources model, we hypothesized that implementing a work-family intervention aimed at increasing contextual resources via supervisor support for work and family, and employee control over work time, would lead to improved personal resources and increased employee performance on the job in the form of self-reported safety compliance and organizational citizenship behaviors. Multilevel analyses used survey data from 1,524 employees at baseline and at 6-month and 12-month postintervention follow-ups. Significant intervention effects were observed for safety compliance at the 6-month, and organizational citizenship behaviors at the 12-month, follow-ups. More specifically, results demonstrate that the intervention protected against declines in employee self-reported safety compliance and organizational citizenship behaviors compared with employees in the control facilities. The hypothesized mediators of perceptions of family-supportive supervisor behaviors, control over work time, and work-family conflict (work-to-family conflict, family-to-work conflict) were not significantly improved by the intervention. However, baseline perceptions of family-supportive supervisor behaviors, control over work time, and work-family climate were significant moderators of the intervention effect on the self-reported safety compliance and organizational citizenship behavior outcomes. |
Elevated soluble CD14 and lower D-dimer are associated with cigarette smoking and heavy episodic alcohol use in persons living with HIV
Cioe PA , Baker J , Kojic EM , Onen N , Hammer J , Patel P , Kahler CW . J Acquir Immune Defic Syndr 2015 70 (4) 400-5 BACKGROUND: Persons living with HIV are at increased risk for cardiovascular disease in part because of persistent inflammation and coagulation activation. METHODS: We examined whether smoking and heavy episodic alcohol use (defined as 5 or more drinks on one occasion) were associated with greater monocyte activation (soluble CD14) and coagulation (D-dimer) in participants in the Study to Understand the Natural History of HIV and AIDS in the Era of Effective Therapy (the "SUN" Study), a prospective observational cohort. RESULTS: Using regression analysis (n = 689), current smoking compared with nonsmoking was associated with significantly elevated soluble CD14 (B = 135.57, 95% confidence interval: 84.95 to 186.19, P < 0.001), whereas heavy alcohol use compared with nonheavy use was associated with significantly lower D-dimer levels (B = -0.059, 95% confidence interval: -0.102 to -0.016, P = 0.007). CONCLUSIONS: Smoking cessation should be encouraged by HIV care providers to improve mortality outcomes from all causes of death, particularly cardiovascular disease. |
High prevalence of low bone mineral density and substantial bone loss over 4 years among HIV-infected persons in the era of modern antiretroviral therapy
Escota GV , Mondy K , Bush T , Conley L , Brooks JT , Onen N , Patel P , Kojic EM , Henry K , Hammer J , Wood KC , Lichtenstein KA , Overton ET . AIDS Res Hum Retroviruses 2015 32 (1) 59-67 HIV-infected persons are living longer on combination antiretroviral therapy (cART) but experiencing more comorbidities including low bone mineral density (BMD). Using data from the Study to Understand the Natural History of HIV and AIDS in the Era of Effective Therapy (SUN Study), we determined the prevalence of low BMD (T-score below one standard deviation of the reference mean) and compared it with matched controls from the National Health and Nutrition Examination Survey (NHANES). We also assessed 4-year longitudinal BMD changes among participants virologically suppressed on cART. Of 653 participants included in this analysis (77% male, 29% black, median age 41 years, median CD4+ cell count 464 cells/mm3, 89% with HIV RNA <400 copies/ml), 51% and 10% had baseline osteopenia and osteoporosis, respectively. Low BMD at the femoral neck was significantly more prevalent than for the NHANES controls (47% versus 29%, p<0.001). Lower body mass index, nonwhite race, longer tenofovir exposure, older age, being unemployed or retired, and lower apolipoprotein E were independently associated with baseline osteoporosis. Among 170 participants virologically suppressed on cART and with longitudinal BMD data, 31% experienced substantial bone loss (≥5% BMD decline from baseline) over 4 years. Female sex, current smoking, and longer stavudine use were more common among participants who had substantial bone loss, although these variables failed to reach statistical significance. Low BMD was highly prevalent among HIV-infected persons. One-third of participants experienced substantial bone loss despite cART, suggesting the need for monitoring and potential clinical interventions. |
Incidence and Predictors of Abnormal Anal Cytology Findings Among HIV-Infected Adults Receiving Contemporary Antiretroviral Therapy
Conley LJ , Bush TJ , Darragh TM , Palefsky JM , Unger ER , Patel P , Steinau M , Kojic EM , Martin H , Overton ET , Cu-Uvin S , Hammer J , Henry K , Wood K , Brooks JT . J Infect Dis 2015 213 (3) 351-60 BACKGROUND: Anal cancer rates are higher for HIV-infected than uninfected adults. Limited published data exist characterizing precursor abnormal anal cytology incidence. METHODS: The Study to Understand the Natural History of HIV/AIDS in the Era of Effective Therapy was a prospective cohort of 700 HIV-infected participants in four U.S. cities. At baseline and annually thereafter, each completed a behavioral questionnaire, and providers collected anorectal swabs for cytologic examination and human papillomavirus (HPV) detection and genotyping. RESULTS: Among 243 participants with negative baseline anal cytology, 37% developed abnormal cytology (incidence rate 13.9/100 person-years [p-y], 95% confidence interval [CI] 11.3 - 16.9) over a median 2.1 years of follow-up. Rates among men having sex with men, women, and men having sex with women, were 17.9 p-y (CI: 13.9 - 22.7), 9.4 p-y (CI: 5.6 - 14.9), 8.9 p-y (CI: 4.8 - 15.6), respectively. In multivariable analysis, number of persistent high-risk HPV (HR) types (adjusted hazards ratio [adjHR] 1.17, CI: 1.01 - 1.36), persistent HR-HPV types except 16 or 18 ([adjHR] 2.46, CI 1.31 - 4.60), and persistent types 16 or 18 (adjHR 3.90, CI: 1.78 - 8.54) remained associated with incident abnormalities. CONCLUSIONS: Abnormal anal cytology incidence was high and more likely to develop among persons with persistent HR-HPV. |
Short communication: the Veterans Aging Cohort Study Index is an effective tool to assess baseline frailty status in a contemporary cohort of HIV-infected persons
Escota GV , Patel P , Brooks JT , Bush T , Conley L , Baker J , Kojic EM , Hammer J , Onen NF . AIDS Res Hum Retroviruses 2015 31 (3) 313-7 The Veterans Aging Cohort Study (VACS) Index has previously been used to identify frail HIV-infected persons. However, data demonstrating the independent association between the VACS Index and baseline frailty status is lacking. Furthermore, the ability of the VACS Index to also reflect transitions in frailty status over time is unknown. We used data from the Study to Understand the Natural History of HIV and AIDS in the Era of Effective Therapy (SUN Study) to determine independent association of baseline frailty status with the VACS Index. We also evaluated VACS Index changes with frailty status transitions over time. We included 303 participants (median age 48 years, 76% men, 57% non-Hispanic white, 91% with plasma HIV RNA <400 copies/ml, and median CD4(+) cell count 595 cells/ml) with baseline and follow-up frailty assessments and used the Fried's criteria to define frailty status. There were 184 (61%) nonfrail, 112 (37%) prefrail, and seven (2%) frail participants at baseline. Prefrail/frail participants had significantly higher median VACS Index scores compared with nonfrail participants (18 versus 10, p<0.001). In multivariable analysis, prefrailty/frailty was independently associated with a higher VACS Index score (odds ratio 1.025, p=0.019). After a median follow-up of 12 months, participants who remained prefrail/frail compared to those who remained nonfrail continued to have higher median VACS Index scores. The VACS Index score did not significantly change with transitions in frailty status over time. Our study highlights the potential utility of the VACS Index in frailty assessment within the clinical setting. |
School-located influenza vaccination with third-party billing: outcomes, cost, and reimbursement
Kempe A , Daley MF , Pyrzanowski J , Vogt T , Fang H , Rinehart DJ , Morgan N , Riis M , Rodgers S , McCormick E , Hammer A , Campagna EJ , Kile D , Dickinson M , Hambidge SJ , Shlay JC . Acad Pediatr 2014 14 (3) 234-40 OBJECTIVE: To assess rates of immunization; costs of conducting clinics; and reimbursements for a school-located influenza vaccination (SLIV) program that billed third-party payers. METHODS: SLIV clinics were conducted in 19 elementary schools in the Denver Public School district (September 2010 to February 2011). School personnel obtained parental consent, and a community vaccinator conducted clinics and performed billing. Vaccines For Children vaccine was available for eligible students. Parents were not billed for any fees. Data were collected regarding implementation costs and vaccine cost was calculated using published private sector prices. Reimbursement amounts were compared to costs. RESULTS: Overall, 30% of students (2784 of 9295) received ≥1 influenza vaccine; 39% (1079 of 2784) needed 2 doses and 80% received both. Excluding vaccine costs, implementation costs were $24.69 per vaccination. The percentage of vaccine costs reimbursed was 62% overall (82% from State Child Health Insurance Program (SCHIP), 50% from private insurance). The percentage of implementation costs reimbursed was 19% overall (23% from private, 27% from Medicaid, 29% from SCHIP and 0% among uninsured). Overall, 25% of total costs (implementation plus vaccine) were reimbursed. CONCLUSIONS: A SLIV program resulted in vaccination of nearly one third of elementary students. Reimbursement rates were limited by 1) school restrictions on charging parents fees, 2) low payments for vaccine administration from public payers and 3) high rates of denials from private insurers. Some of these problems might be reduced by provisions in the Affordable Care Act. |
Models for count data with an application to healthy days measures: are you driving in screws with a hammer?
Zhou H , Siegel PZ , Barile J , Njai RS , Thompson WW , Kent C , Liao Y . Prev Chronic Dis 2014 11 E50; quiz E50 INTRODUCTION: Count data are often collected in chronic disease research, and sometimes these data have a skewed distribution. The number of unhealthy days reported in the Behavioral Risk Factor Surveillance System (BRFSS) is an example of such data: most respondents report zero days. Studies have either categorized the Healthy Days measure or used linear regression models. We used alternative regression models for these count data and examined the effect on statistical inference. METHODS: Using responses from participants aged 35 years or older from 12 states that included a homeownership question in their 2009 BRFSS, we compared 5 multivariate regression models - logistic, linear, Poisson, negative binomial, and zero-inflated negative binomial - with respect to 1) how well the modeled data fit the observed data and 2) how model selections affect inferences. RESULTS: Most respondents (66.8%) reported zero mentally unhealthy days. The distribution was highly skewed (variance = 58.7, mean = 3.3 d). Zero-inflated negative binomial regression provided the best-fitting model, followed by negative binomial regression. A significant independent association between homeownership and number of mentally unhealthy days was not found in the logistic, linear, or Poisson regression model but was found in the negative binomial model. The zero-inflated negative binomial model showed that homeowners were 24% more likely than nonowners to have excess zero mentally unhealthy days (adjusted odds ratio, 1.24; 95% confidence interval, 1.08-1.43), but it did not show an association between homeownership and the number of unhealthy days. CONCLUSION: Our comparison of regression models indicates the importance of examining data distribution and selecting models with appropriate assumptions. Otherwise, statistical inferences might be misleading. |
Fleet safety: developing & sustaining an effective program with ANSI/ASSE Z15.1
Hammer BS , Pratt SG , Ross P . Prof Saf 2014 59 (3) 47-56 The risk of work-related motor vehicle crashes cuts across all industries and occupations. Between 2003 and 2008, workers employed by truck transportation companies had the highest risk of work-related fatality due to vehicle crashes while driving or riding in a motor vehicle on a public roadway. This article discusses how ANSI/ASSE Z15.1-2012 provides comprehensive guidance on fleet safety program elements and can be used as a foundation for auditing an existing program. |
Mortality from cancer and other causes in commercial airline crews: a joint analysis of cohorts from 10 countries
Hammer GP , Auvinen A , De Stavola BL , Grajewski B , Gundestrup M , Haldorsen T , Hammar N , Lagorio S , Linnersjo A , Pinkerton L , Pukkala E , Rafnsson V , Dos-Santos-Silva I , Storm HH , Strand TE , Tzonou A , Zeeb H , Blettner M . Occup Environ Med 2014 71 (5) 313-22 BACKGROUND: Commercial airline crew is one of the occupational groups with the highest exposures to ionising radiation. Crew members are also exposed to other physical risk factors and subject to potential disruption of circadian rhythms. METHODS: This study analyses mortality in a pooled cohort of 93 771 crew members from 10 countries. The cohort was followed for a mean of 21.7 years (2.0 million person-years), during which 5508 deaths occurred. RESULTS: The overall mortality was strongly reduced in male cockpit (SMR 0.56) and female cabin crews (SMR 0.73). The mortality from radiation-related cancers was also reduced in male cockpit crew (SMR 0.73), but not in female or male cabin crews (SMR 1.01 and 1.00, respectively). The mortality from female breast cancer (SMR 1.06), leukaemia and brain cancer was similar to that of the general population. The mortality from malignant melanoma was elevated, and significantly so in male cockpit crew (SMR 1.57). The mortality from cardiovascular diseases was strongly reduced (SMR 0.46). On the other hand, the mortality from aircraft accidents was exceedingly high (SMR 33.9), as was that from AIDS in male cabin crew (SMR 14.0). CONCLUSIONS: This large study with highly complete follow-up shows a reduced overall mortality in male cockpit and female cabin crews, an increased mortality of aircraft accidents and an increased mortality in malignant skin melanoma in cockpit crew. Further analysis after longer follow-up is recommended. |
The effects of impact vibration on peripheral blood vessels and nerves
Krajnak KM , Waugh S , Johnson C , Miller GR , Xu X , Warren C , Dong RG . Ind Health 2013 51 (6) 572-80 Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a single bout of impact vibration (15 min exposure, at a dominant frequency of 30 Hz and an unweighted acceleration of approximately 345 m/s(2)) generated by a riveting hammer. Responsiveness of the ventral tail artery to adrenoreceptor-mediated vasoconstriction and acetylcholine-mediated re-dilation was measured ex vivo. Ventral tail nerves and nerve endings in the skin were assessed using morphological and immunohistochemical techniques. Impact vibration did not alter vascular responsiveness to any factors or affect trunk nerves. However, 4 days following exposure there was an increase in protein-gene product (PGP) 9.5 staining around hair follicles. A single exposure to impact vibration, with the exposure characteristics described above, affects peripheral nerves but not blood vessels. |
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