Mean Exposure Time Research Articles

Pharyngeal and oesophageal dysmotility and dysfunction in patients with chronic cough: assessment by high-resolution manometry

IntroductionLaryngopharyngeal reflux (LPR) of gastric contents is a cause of chronic cough; however the pathophysiology of this disease remains unclear. Conventional manometry has insufficient spatial resolution for the functional assessment...

Toxicity of eight metals to Malaysian freshwater midge larvae Chironomus javanus (Diptera, Chironomidae)

Fourth instars larvae of freshwater midge Chironomus javanus (Diptera, Chironomidae) were exposed for a 4-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al) and manganese (Mn) concentrations. Mortality was assessed and median lethal concentrations (LC(50)) were calculated. LC(50) increased with the decrease in mean exposure times, for all metals. LC(50)s for 96 hours for Cu, Cd, Zn, Pb, Ni, Fe, Al and Mn were 0.17, 0.06, 5.57, 0.72, 5.32, 0.62, 1.43 and 5.27 mg/L, respectively. Metals bioconcentration in C. javanus increases with exposure to increasing concentrations and Cd was the most toxic to C. javanus, followed by Cu, Fe, Pb, Al, Mn, Zn and Ni (Cd > Cu > Fe > Pb > Al > Mn > Zn > Ni). Comparison of LC(50) values for metals for this species with those for other freshwater midges reveals that C. javanus is equally or more sensitive to metals than most other tested dipteran.

Sensitivity of the freshwater prawn, Macrobrachium lanchesteri (Crustacea: Decapoda), to heavy metals

Adult Macrobrachium lanchesteri were exposed for a 4-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn) and lead (Pb) concentrations. Mortality was assessed and median lethal times (LT₅₀) and concentrations (LC₅₀) were calculated. At the end of the 4-day period, live prawns were used to determine bioconcentration of the metals. LT₅₀ and LC₅₀ increased with the decrease in mean exposure concentrations and times, respectively, for all metals. LC₅₀s for 96 hours for Cu, Cd, Zn and Pb were 32.3, 7.0, 525.1 and 35.0 µg/L, respectively. Cu, Cd, Zn and Pb bioconcentration in M. lanchesteri increases with exposure to increasing concentrations and Cd was the most toxic to M. lanchesteri, followed by Pb, Cu and Zn. Comparison of LC₅₀ values for metals for this species with those for other freshwater crustacean organisms reveals that M. lanchesteri is equally or more sensitive to heavy metals than most other tested crustaceans.

Toxicity of Metals to a Freshwater Ostracod:Stenocypris major

Adults of freshwater ostracod Stenocypris major (Crustacea, Candonidae) were exposed for a four-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al), and manganese (Mn) concentrations. Mortality was assessed, and median lethal times (LT50) and concentrations (LC50) were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively, for all metals. LC50s for 96 hours for Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 25.2, 13.1, 1189.8, 526.2, 19743.7, 278.9, 3101.9, and 510.2 μg/L, respectively. Metals bioconcentration in S. major increases with exposure to increasing concentrations, and Cd was the most toxic to S. major, followed by Cu, Fe, Mn, Pb, Zn, Al, and Ni (Cd>Cu>Fe>Mn>Pb>Zn>Al>Ni). Comparison of LC50 values for metals for this species with those for other freshwater crustacean reveals that S. major is equally or more sensitive to metals than most other tested crustacean.

Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein.

ObjectiveWorkers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins.Materials and methods67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ± 10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization.ResultsChromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ± 9.1 in the exposed group vs. 65.7 ± 10.5 years in controls; P = 0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ± 12.7 vs. 12.1 ± 21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. P53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed.ConclusionThe study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma.

New Insights into Pacemaker Lead-Induced Venous Occlusion: Simulation-Based Investigation of Alterations in Venous Biomechanics

Venous obstruction is a major complication of transvenous pacemaker placement. Despite the increasing use of pacemakers and implantable cardiac defibrillators, a lack of understanding remains with regard to risk factors for the development of device-associated venous obstruction. We hypothesize that computational fluid dynamics simulations can reveal prothrombogenic locations and define thrombosis risk based on patient-specific anatomies. Using anatomic data derived from computed tomography, computer models of the superior vena cava, subclavian, innominate, and internal jugular veins were constructed for three adult patients with transvenous pacemakers. These models were used to perform patient-specific simulations examining blood flow velocity, wall shear stress, and blood pressure, both with and without the presence of the pacing leads. To better quantify stasis, mean exposure time fields were computed from the venous blood flow data. In comparing simulations with leads to those without, evident increases in stasis at locations between the leads and along the surface of the vessels closest to the leads were found. These locations correspond to regions at known risk for thrombosis. This work presents a novel application of computational methods to study blood flow changes induced by pacemaker leads and possible complications such as venous occlusion and thrombosis. This methodology may add to our understanding of the development of lead-induced thrombosis and occlusion in the clinical arena, and enable the development of new strategies to avoid such complications.

Fast Line Scan Confocal Microscope with Minimal Photobleaching

We report on a custom-built high speed laser scanning confocal microscope that produces high quality images in the diffraction limit with minimal photobleaching. The image resolution and contrast are increased when the sample is scanned by a finely focused illumination source by a 50 μm confocal pinhole at the laser illumination source. With the use of high speed resonant scanning mirrors (8kHz), and given a scanning field of 200μm x 200μm and a laser spot size of 250nm at the diffraction limit, the mean exposure time for a single fluorophores is ∼ 80ns (250nm/(2∗8kHz∗200μm)).

Evaluación de los efectos del glifosato y otros plaguicidas en la salud humana en zonas objeto del programa de erradicación de cultivos ilícitos

The herbicide glyphosate is administered aerially by the Program to Eradicate Illicit Crops Program and is undertaken in rigorous compliance with the Environmental Management Plan. The effects of the glyphosate herbicide and other aerially applied insecticides were measured to determine possible impact on human health. In 2006-2006, a survey was taken of 112 individuals living in herbicide-treated areas of the Colombian provinces of Huila, Tolima, Putumayo, Guaviare, Santander, Antioquia, Magdalena and La Guajira. Samples of blood were examined for presence of acetylcholinesterase and organochlorine insecticides; urine was analyzed for glyphosate and its metabolites. Fifty percent (50%) of the individuals sampled acknowledged the use of control chemicals as part of their work. The mean exposure time to the chemicals was 84.4 months, with a mean daily exposure of 5.6 hours. The most commonly used pesticides were of category I--extremely hazardous. In individuals sampled for glyphosate (39.6% of the total), 64.3% indicated the use of this herbicide at ground level in agricultural work. A statistically significative relationship was found between the use of glyphosate at ground level, and the concentration levels of glyphosate in the urine samples (odds ratio=2.54, 95% CI: 1.08 to 6.8). These data did not show a relationship between the aerial sprayings of glyphosate for illicit crops eradication and an impact on human health, nor with occupational exposure to this and other chemicals (insecticides) with a high levels of toxicity.

Alterações auditivas em trabalhadores expostos a mercúrio

OBJETIVO: identificar possíveis alterações auditivas periféricas e centrais, em trabalhadores de uma indústria de reciclagem de lâmpadas fluorescentes, que tiveram exposição ao mercúrio metálico. MÉTODOS: foram realizados os testes de audiometria tonal (via aérea e via óssea), audiometria vocal e imitanciometria (timpanometria e pesquisa do reflexo estapediano) em 13 trabalhadores, todos do sexo masculino, com idade média de 38,5 anos e tempo médio de exposição de seis anos. Após foram realizados os teste de processamento auditivo (dicótico de dígitos e PPS) em nove trabalhadores. RESULTADOS: dos 13 sujeitos que realizaram a audiometria e a imitanciometria, seis (46%) apresentaram perda auditiva sensório-neural e sete (54%) apresentaram alteração no reflexo estapediano. Dos nove sujeitos que realizaram o teste de processamento auditivo, três (33,5%) apresentaram resultados alterados tanto no teste dicótico de dígitos, quanto no PPS. CONCLUSÕES: foram identificadas tanto alterações auditivas periféricas quanto centrais.

MR Arthrography of the Shoulder Using an Anterior Approach: Optimal Injection Site

The purpose of our study was to optimize anterior MR arthrography of the shoulder by comparing three injection sites. Seventy-eight patients were divided into three groups of 26 each, according to the injection site selected: the upper third of the medial part of the humeral head, the lower third of the medial part of the humeral head, or the area between the middle and lower thirds of the glenohumeral joint. A marker plate with radiopaque coordinates was used in performing the technique. Radiologist time and exposure time were recorded, and the intensity of the patient's pain was measured using a Visual Analogue Scale (VAS). Groups were compared using variance analysis and the least significant difference method. Shoulder arthrography was considered satisfactory for all three injection sites. Mean exposure time was 20.9 +/- 7.8 (SD) milliseconds, and mean radiologist time was 6.4 +/- 0.8 minutes. Mean pain intensity registered by the VAS was 1.7 +/- 0.9, the lowest values tending to be those recorded by patients who received an injection in the upper third. Exposure and radiologist times were lower for these latter patients; differences between the upper third and the other two areas were statistically significant (p < 0.005). The optimal injection site for anterior MR arthrography of the shoulder is the upper third of the humeral head, a simple, rapid procedure that is well tolerated by patients and reduces the radiation dose administered.

Noise Levels, Hearing Disturbances, and Use of Hearing Protection at Entertainment Venues

An investigation of noise levels experienced by patrons and workers at entertainment venues, and a survey of exposure times, experience of adverse effects, attitudes towards noise levels and hearing protection, use of hearing protection, and knowledge of noise induced hearing loss (NIHL) education campaigns were undertaken. Noise level measurements were taken at various points in the venues and a questionnaire was conducted with 303 of the patrons. Mean recorded sound levels exceeded 95 dB (A) and mean exposure time was almost five hours per session. The majority (81%) of respondents had suffered auditory symptoms such as temporary hearing loss, tinnitus and headache. The use of earplugs was low, especially in females and those under 26 years old. The results suggest that regular patrons and staff of these venues are at risk of NIHL. Recollection of a NIHL education campaign does not appear to influence the rate of hearing protection use. Regulating the noise level of venues must be considered as the most effective strategy to prevent NIHL.

Exposition professionnelle aux poussières de bois et cancers naso-sinusiens

Objectives To determine the clinical, histological, epidemiological and occupational data related to exposure to wood dust in a series of 100 nasal sinus malignant tumors. Material and methods We conducted a retrospective and descriptive study of cases diagnosed between 1st January 1981 and 31 December 2000, in the Auvergne region of France. Individual, medical, and occupational data were collected from a questionnaire completed by the patient (or the patient's family in case of death) and from the medical documents available. Results Forty-six cases (46 men), with an average age of 63 ± 9.2 years [range, 43–82], had been exposed to occupational wood dust before the diagnosis. Fifty-four cases (30 men, 24 women), with an average age of 64.3 ± 8.7 years [range, 40–96], had never been exposed. The average annual incidence increased, either for the total population or for the two subgroups distinguished on the basis of occupational exposure to wood dust. The majority of the patients presented different functional symptoms at the time of the diagnosis. For the 46 patients exposed to wood dust, the tumors were primarily ethmoid adenocarcinomas (92%). For the 54 non-exposed patients, the tumors observed were mainly epidermoid carcinomas (57%), then adenocarcinomas (15%). On the 46 patients exposed to wood dust, 85% were carpenters or cabinetmakers. For the majority of the patients, wood dust exposure started before the age of 20 (average age: 17 ± 4.5) and the longest exposure began before 1981. The exposure time to wood dust before diagnosis was in the majority of cases greater than 20 years (mean exposure time: 37 years ± 11.4). Only 15% were exposed at the time of the diagnosis (mean time between the end of the exposure to the diagnosis was 11 years ± 2.8). Of the 54 non-exposed patients, no professional risk factor was evidenced. Conclusion Epidemiologic data, such as the increasing incidence, and clinical and professional data, such as the occupational exposure to wood dust, were in agreement with the French and European literature. It is still probably too early to appreciate the effectiveness of prevention, established in France since 1980, on nasal sinus tumor incidence.

Effects of Endoscopic Full-Thickness Plication On GERD Measured By Multichannel Intraluminal Impedance Monitoring

Background: Endoscopic full-thickness plication (Plicator®) has been shown to be effective at controlling reflux symptoms and esophageal acid exposure in a recently published prospective randomized, sham-controlled trial. By means of multichannel intraluminal impedance monitoring (MII), detection of nonacid or weakly acidic reflux events, aerophagia, and differentiation of true reflux events from non-reflux events is possible. In this study, the effects of endoscopic full-thickness plication measured by MII was analysed. Patients and Methods: 11 patients requiring maintenance proton pump inhibitor therapy underwent endoscopic full-thickness plication for treatment of gastro-esophageal reflux disease (GERD). MII was performed off-medication before and 6 month after endoscopic full-thickness plication in all patients. The effect of endoscopic full-thickness plication on acid, nonacid and weakly acidic reflux events were assessed. Results: 11 patients underwent endoscopic full-thickness plication using two or three serially placed Plicator implants. The mean number of total reflux and acid reflux episodes significantly decreased after the procedure (123 vs. 63, p < 0.02, 75 vs. 37, p < 0.02. The mean acid exposure time significantly decreased after treatment (124 min. vs. 41 min., p < 0.01). Total reflux exposure time and the mean DeMeester score significantly decreased after treatment (9.2% vs. 2.9%, p < 0.01, 27 vs. 9, p < 0.01).). The mean number of non-acid reflux episodes were not significantly decreased after the procedure (48 vs. 26, p = 0.306). The median bolus clearance time was not significantly changed (12 sec. vs. 11 sec. p = 0.798). Conclusions: Evaluation of endoscopic full-thickness plication efficacy by MII showed significant reduction in the mean number of total reflux episodes, acid reflux episodes and total reflux exposure time. Furthermore, the mean DeMeester score and the mean total acid exposure time in the distal esophagus were significantly decreased. No significant decrease was measured for non-acid reflux episodes or the median bolus clearance time.

Quantitative assessment of neuromotor function in workers with current low exposure to mercury vapor

Evaluation of neuromotor function has been used in several epidemiological studies of workers with long-term exposure to mercury vapor (Hg 0). Some recent studies indicate adverse effects at relatively low exposure levels. In the present study, we used sensitive quantitative methods, developed specifically to detect subtle effects of exposure to toxins on motor function. After exclusion of individuals with neurological diseases or other conditions that may affect performance, 43 chloralkali workers with current low exposure to Hg 0, and 22 age-matched referents remained for further analysis. The median urinary mercury concentration in exposed workers was 5.9 μg/g (range 1.3–25) creatinine (μg/gC), while that in referents was 0.7 μg/gC (range 0.2–4.1). The mean exposure time was 15 years, and the median cumulative mercury index was 161 years × μg/gC in exposed workers. A eurythmokinesimeter (EKM) was used to quantify eye–hand coordination, and a diadochokinesimeter, to measure rapid alternating rotation of the forearms. In general, the differences in performance between the exposed workers and the referents were small. Age was associated with a decrease in speed, more tremor, and longer contact duration between the stylus and the metal targets in performance of rapid pointing movements. Smokers had significantly more tremor, and more contacts per event in the EKM test, than nonsmokers. Taking age, shift work, and smoking habits into account, no significant associations with current or cumulative mercury exposure were found for the majority of the outcome variables from the quantitative tests. In general, this study indicates no significant adverse effects of Hg 0 on neuromotor function at the exposure levels studied.

CENTRAL VENOUS ACCESS PORTS IN CHILDREN TREATED FOR HEMATOPOIETIC MALIGNANCIES

During past 10 years 234 central venous access ports (CVAP) were implanted in 225 patients at the Department of Pediatric Hematology and Oncology in Zabrze. Mean exposure time was 745 days and total implantation time reached 173,768 days. Complications were encountered in 17 patients (7.6%). This mainly concerned central venous line infection, which led to removal of 10 CVAP (4.4%). The remaining complications necessitating removal of the CVAP consisted mainly of mechanical problems (catheter fracture, occlusion, and erroneous implantation to artery). In the opinion of the authors, subcutaneously implanted CVAP are a safe and effective option for high-dose chemotherapy deliverance in childhood cancer patients.

Trauma Scissors vs. the Rescue Hook, Exposing a Simulated Patient: A Pilot Study

The objective of this study was to compare the exposure times using trauma scissors vs. the rescue hook on a simulated patient. This was a prospectively randomized, parallel group comparison study with two arms. The control group used trauma scissors (15 cycles), and the intervention group used rescue hooks (15 cycles). The uniform and footwear were standardized for each cycle. Ten participants were trained on each instrument. For each cycle, four participants were randomly chosen, and the use of either instrument was randomized. Each participant was then queried about their preferences for either instrument and why. The rescue hook's mean time of exposure was 24 s with a SD of 7 s and a 95% confidence interval (CI) of 20–28 s. The trauma scissors' mean exposure time was 42 s with a SD of 5 s and a 95% CI of 39–45 s. The mean difference was 18 s, with a 95% CI of 13–23 s. On average, the rescue hook was 43% faster. Nine of 10 participants preferred the rescue hook, stating that it was faster, easier, smaller, and more durable. The rescue hook was found to be faster than trauma scissors when exposing a simulated patient, and it was the instrument preferred by the majority of participants.

Skin exposure in geriatric care – a comparison between observation and self‐assessment of exposure

The aim of this study was to compare observation and self-assessment of skin exposure to irritants during a working day in nursing in geriatric care. The study group consisted of 40 volunteers, 13 nurses, and 27 assistant nurses. Before the start of a working day, the participants completed a questionnaire regarding skin exposure to water, gloves, hand disinfection, and moisturizers. Observers subsequently used a hand-held computer to register the time and frequency of each exposure. The total mean skin exposure time was 96 min per working day, including glove use. The mean exposure time to water was 9 min per working day. A tendency to overestimate was found for all exposures. A strong correlation between self-reports and observations was found for hand disinfection and moisturizers, while a moderate correlation was found for gloves and number of water exposures and a weak correlation for total time of water exposure. Despite the differences between self-assessment and observation of the exposure, we consider the questionnaire to be useful for surveying skin exposure in nursing. Furthermore, the observations in this study suggest that nursing work in geriatric care may comprise limited exposure to water.

Quantitative Assessment of Neuromotor Function in Workers With Current Low Exposure to Mercury Vapor

Evaluation of neuromotor function has been used in several epidemiological studies of workers with long-term exposure to mercury vapor (Hg 0). Some recent studies indicate adverse effects at relatively low exposure levels. In the present study, we used sensitive quantitative methods, developed specifically to detect subtle effects of exposure to toxins on motor function. After exclusion of individuals with neurological diseases or other conditions that may affect performance, 43 chloralkali workers with current low exposure to Hg 0, and 22 age-matched referents remained for further analysis. The median urinary mercury concentration in exposed workers was 5.9 microg/g (range 1.3-25) creatinine (microg/gC), while that in referents was 0.7 microg/gC (range 0.2-4.1). The mean exposure time was 15 years, and the median cumulative mercury index was 161 years x microg/gC in exposed workers. A eurythmokinesimeter (EKM) was used to quantify eye-hand coordination, and a diadochokinesimeter, to measure rapid alternating rotation of the forearms. In general, the differences in performance between the exposed workers and the referents were small. Age was associated with a decrease in speed, more tremor, and longer contact duration between the stylus and the metal targets in performance of rapid pointing movements. Smokers had significantly more tremor, and more contacts per event in the EKM test, than nonsmokers. Taking age, shift work, and smoking habits into account, no significant associations with current or cumulative mercury exposure were found for the majority of the outcome variables from the quantitative tests. In general, this study indicates no significant adverse effects of Hg 0 on neuromotor function at the exposure levels studied.

Characteristics of Patients with Reflux Esophagitis, Non-Erosive Reflux Disease and Functional Heartburn

Purpose: Patients with non-erosive reflux disease (NERD) account for up to 70% of the gastroesophageal reflux disease (GERD) population and represent a heterogenous group. Our aim was to compare the demographics and clinical characteristics of patients with reflux esophagitis (RE), NERD, and functional heartburn (FH). Methods: We reviewed the medical records of 81 consecutive patients with frequent heartburn and regurgitation on whom Bravo™ capsule 48-h esophageal pH monitoring was performed after capsule placement under endoscopic guidance. Patients were instructed to stop taking acid-suppressive therapy at least 7 days before the pH study. An abnormal study was defined as either a DeMeester score ≥ 14.72 or a mean acid exposure time (the percentage of time pH less than 4) ≥ 4.5%. Patients with esophageal mucosal injury observed during capsule placement or during a prior endoscopy comprised the RE group. The remaining patients were divided into two groups according to pH monitoring study results: NERD (those with an abnormal pH study) and functional heartburn (FH) (those with a normal pH study). Chi-square and t-test were used to compare categorical and continuous data between groups. Results: Of 81 patients, 28 (35%) were in the RE group, 27 (51%) comprised the NERD group and 26 (49%) met our criteria for the FH group. No statistically significant difference was found between the three groups in distribution with respect to age, prevalence of hiatal hernia, and presenting symptoms, except that patients with RE had more respiratory symptoms (cough, hoarseness, shortness of breath) compared to patients with NERD or FH (See Table), and patients with FH were more likely to be female. Interestingly, only 16 of 28 RE patients had an abnormal pH study. Conclusion: Patients with RE experience more respiratory symptoms compared to patients with NERD or FH. As only 57% of RE patients had an abnormal pH study, factors other than acid exposure may contribute to the development of esophagitis. FH is more common in women than men.Table

Analgesic nephropathy

Analgesic nephropathy