Analysis of polycyclic aromatic hydrocarbons (PAHs) in air using passive sampling calibrated with active measurements.

There are limited ambient air measurements of extended (beyond EPA Priority 16) lists of polycyclic aromatic hydrocarbons (PAHs). We measured air concentrations of 45 PAHs using passive and active air sampling at 15 sites in a central urban community and one rural site for two years. Passive sampling was conducted with cylindrical XAD-based samplers deployed to capture spatial variability. High volume active samplers with quartz fiber filters for particles and XAD-4 absorbent for gases were deployed at two urban sites and the rural site to calibrate the passive measurements directly. Estimated passive sampling rates (PSRs) were evaluated as functions of meteorological data, seasons, locations, study year, and compared with other studies. Possible particle collection by the passive samplers was evaluated using a variety of particle measurements (TSP, PM10, PM2.5 and ultrafines <100 nm). Total PAHs were statistically associated with ultrafine particle concentrations and to a lesser extent PM2.5 and PM10, but not TSP. PSRs were more variable when PAH mass loadings were lower and near method detection limits; this occurred more often at the rural site. The PSRs were not statistically associated with meteorological conditions in this study, but wind speed had the highest potential to impact PSR results. The resulting passive PAH measurements are reported with respect to proximity to major roadways and other known air emissions types. PSRs were quantifiable for some PAHs that were found predominantly in the particulate phase in active sampling. This information, together with particle fraction calculations from active sampling, were used to estimate the particulate PAH capture of the passive sampler. Summed PAH (∑PAH) passive concentrations were measured within the range of 10-265 ng/m3, with the highest concentrations from naphthalene and the lowest detected concentrations from anthracene. These results indicated a stronger seasonal signal within 200 m of a major roadway.

Inappropriate documentation of heparin allergy in the medical record because of misdiagnosis of heparin-induced thrombocytopenia: frequency and consequences.

Essentials Misdiagnosis of heparin-induced thrombocytopenia (HIT) may be associated with adverse outcomes. We conducted a study of patients with a heparin allergy in the chart due to misdiagnosis of HIT. 42% of patients with a heparin allergy due to suspected HIT were clearly HIT-negative. 68% were unnecessarily treated with an alternative anticoagulant, 66% of whom had major bleeding. SUMMARY: Background It is recommended that heparin be added to the allergy list of patients with heparin-induced thrombocytopenia (HIT). Misdiagnosis of HIT could lead to inappropriate documentation of a heparin allergy and adverse outcomes. Objectives To determine the frequency and consequences of inappropriate documentation of a heparin allergy because of misdiagnosis of HIT. Methods We conducted a cohort study of patients with an inappropriate heparin allergy listed in the electronic medical record (EMR) because of misdiagnosis of HIT. We searched the EMR for patients with a new heparin allergy. Patients were eligible if the reason for allergy listing was suspected acute HIT and laboratory testing for HIT was performed within 60 days. Subjects were defined as 'HIT-negative' if they had a 4Ts score of ≤ 3 or negative laboratory test results. Results Of 239 subjects with a new heparin allergy documented because of concern regarding HIT, 100 (42%) met the prespecified definition of HIT-negative. Sixty-eight (68%) HIT-negative subjects unnecessarily received an alternative parenteral anticoagulant for a median duration of 10.5 days. Among these 68 patients, 45 (66%) met criteria for major bleeding. Sixty-eight (68%) of the 100 HIT-negative subjects had an inappropriate allergy to heparin documented that persisted in the EMR for > 3 years beyond the index hospitalization. Conclusions Inappropriate listing of heparin as an allergy in the EMR because of misdiagnosis of HIT is common, is associated with substantial rates of unnecessary alternative anticoagulant use and major bleeding, and tends to persist beyond the index admission.

Association between diet quality with concurrent vision and hearing impairment in older adults.

OBJECTIVES: Published literature shows that individual nutrients could influence the risk of developing vision and hearing loss. There is, however, a lack of population-based data on the relationship between overall patterns of food intake and the presence of concurrent vision and hearing impairment. We aimed to assess the associations between diet quality with the prevalence and 5-year incidence of dual sensory impairment (DSI). DESIGN: Cross-sectional and 5-year longitudinal analyses. SETTING: Blue Mountains, Sydney, Australia. PARTICIPANTS: 2443 participants aged ≥50 from baseline were examined and followed over 5 years. MEASUREMENTS: Dietary data were collected using a semi-quantitative food frequency questionnaire. A modified version of the Healthy Eating Index for Australians was developed to determine total diet score (TDS). Visual impairment was defined as visual acuity less than 20/40 (better eye), and hearing impairment as average pure-tone air conduction threshold greater than 25 dB HL (500-4000 Hz, better ear). RESULTS: After adjusting for age, sex, education, noise exposure, current smoking, and type 2 diabetes, participants in the lowest compared to the highest quintile of TDS had a 2-fold increased likelihood of having prevalent DSI, odds ratio, OR, 2.62 (95% confidence intervals, CI, 1.08-6.36), P-trend=0.04. Significant associations were not observed between TDS and the prevalence of having a single sensory impairment (vision or hearing loss). Baseline TDS was not significantly associated with the 5-year incidence of DSI. Adherence to dietary guidelines was associated with a reduced likelihood of having DSI in cross-sectional, but not in longitudinal analyses. CONCLUSIONS: Further studies with adequate power are warranted to assess the prospective relationship between diet quality and DSI.

Dietary antioxidant intake is associated with the prevalence but not incidence of age-related hearing loss.

OBJECTIVES: Diet is one of the few modifiable risk factors for age-related hearing loss. We aimed to examine the link between dietary and supplement intakes of antioxidants, and both the prevalence and 5-year incidence of measured hearing loss. DESIGN: Cross-sectional and 5-year longitudinal analyses. SETTING: Blue Mountains, Sydney, Australia. PARTICIPANTS: 2,956 Blue Mountains Hearing Study participants aged 50+ at baseline, examined during 1997-9 to 2002-4. MEASUREMENTS: Age-related hearing loss was measured and defined as the pure-tone average of frequencies 0.5, 1.0, 2.0 and 4.0 kHz >25 dB HL. Dietary data were collected in a semi-quantitative food frequency questionnaire, and intakes of α-carotene; ß-carotene; ß-cryptoxanthin; lutein and zeaxanthin; lycopene; vitamins A, C and E; iron and zinc were calculated. RESULTS: After adjusting for age, sex, smoking, education, occupational noise exposure, family history of hearing loss, history of diagnosed diabetes and stroke, each standard deviation (SD) increase in dietary vitamin E intake was associated with a 14% reduced likelihood of prevalent hearing loss, odds ratio, OR, 0.86 (95% confidence interval, CI, 0.78-0.98). Those in the highest quintile of dietary vitamin A intake had a 47% reduced risk of having moderate or greater hearing loss (>40 dB HL) compared to those in the lowest quintile of intake, multivariable-adjusted OR 0.53 (CI 0.30-0.92), P for trend = 0.04. However, dietary antioxidant intake was not associated with the 5-year incidence of hearing loss. CONCLUSIONS: Dietary vitamin A and vitamin E intake were significantly associated with the prevalence of hearing loss. However, dietary antioxidant intake did not increase the risk of incident hearing loss. Further large, prospective studies are warranted to assess these relationships in older adults.

The effects of smoking and alcohol consumption on age-related hearing loss: the Blue Mountains Hearing Study.

OBJECTIVES: We aimed to investigate the temporal association between smoking or alcohol consumption and hearing loss, and to confirm previously published cross-sectional associations. DESIGN: The Blue Mountains Hearing Study is a population-based survey of age-related hearing loss conducted in a defined suburban area, west of Sydney. Hearing loss was measured in 2956 participants (aged 50+ yrs) and was defined as the pure-tone average of frequencies 0.5, 1.0, 2.0, and 4.0 kHz >25 dB HL in the better ear (bilateral hearing loss). Alcohol consumption and smoking status were measured using an interviewer-administered questionnaire. Logistic regression was used to obtain odds ratios (OR) with 95% confidence intervals (95% CI) that compared the chances of having hearing loss in participants who did or did not smoke or consume alcohol, after adjusting for other factors previously reported to be associated with hearing loss. RESULTS: The prevalence of hearing loss at baseline was 33.0% (N = 929) and the 5-year incidence of hearing loss was 17.9% (N = 156). Cross-sectional analysis demonstrated a significant protective association between the moderate consumption of alcohol (>1 but < or =2 drinks/day) and hearing function in older adults (compared with nondrinkers), OR 0.75 (95% CI, 0.57 to 0.98). Current smokers not exposed to occupational noise had a significantly higher likelihood of hearing loss after adjusting for multiple variables, OR 1.63 (95% CI, 1.01 to 2.64). A formal likelihood ratio test demonstrated that the interaction between smoking and noise exposure was not significant (p = 0.23). When the joint effects of alcohol consumption and smoking on hearing were explored, there was a trend for alcohol to have a protective relationship with hearing loss in smokers, but this was not statistically significant. However, the 5-year incidence of hearing loss was not predicted by either smoking or alcohol consumption. CONCLUSIONS: This study confirms previously reported associations between alcohol consumption or smoking and prevalent hearing loss, but these were not demonstrated in temporal data. Other risk factors could confer greater vulnerability or cause the initial damage to hearing. Future large population-based studies, exploring the influence of other risk factors on the development of age-related hearing loss are warranted.

Relationship of Type 2 diabetes to the prevalence, incidence and progression of age-related hearing loss.

AIMS: Type 2 diabetes and associated microvascular abnormalities are postulated to affect hearing. Our study reports on the relationship between Type 2 diabetes and the prevalence, 5-year incidence and progression of hearing impairment in a representative, older, Australian population. METHODS: The Blue Mountains Hearing Study is a population-based survey of age-related hearing loss conducted in a defined suburban area, west of Sydney. Hearing loss was defined as the pure-tone average of frequencies 0.5, 1.0, 2.0 and 4.0 kHz > 25 decibels hearing level (dB HL) in the better ear (bilateral hearing loss). Type 2 diabetes was defined from reported physician-diagnosed diabetes or fasting blood glucose > or = 7.0 mmol/l. RESULTS: Age-related hearing loss was present in 50.0% of diabetic participants (n = 210) compared with 38.2% of non-diabetic participants (n = 1648), odds ratio (OR) 1.55 [95% confidence interval (CI) 1.11-2.17], after adjusting for multiple risk factors. A relationship of diabetes duration with hearing loss was also demonstrated. After 5 years, incident hearing loss occurred in 18.7% of participants with, and 18.0% of those without diabetes, adjusted OR 1.01 (CI 0.54-1.91). Progression of existing hearing loss (> 5 dB HL), however, was significantly greater in participants with newly diagnosed diabetes (69.6%) than in those without diabetes (47.8%) over this period, adjusted OR 2.71 (CI 1.07-6.86). CONCLUSIONS: Type 2 diabetes was associated with prevalent, but not incident hearing loss in this older population. Accelerated hearing loss progression over 5 years was more than doubled in persons newly diagnosed with diabetes. These data explore further reported links between Type 2 diabetes and age-related hearing loss.

Dizziness and vertigo in an older population: the Blue Mountains prospective cross-sectional study.

OBJECTIVES: We aimed to reassess the prevalence and personal burden of dizziness/vertigo, and to assess the relationship with hearing loss and tinnitus in older adults. DESIGN: Prospective cross-sectional study. SETTING: Blue Mountains region, west of Sydney, Australia. PARTICIPANTS: We examined 2751 of 2956 (aged 50+ years) Blue Mountains Hearing Study participants. MAIN OUTCOME MEASURES: Audiologists screened participants for reported dizziness using a single question. Questions from the Dizziness Handicap Inventory were used to assess the impacts of dizziness/vertigo. Hearing impairment was determined as the pure-tone average of audiometric hearing thresholds at 500, 1000, 2000 and 4000 Hz (PTA(0.5-4 KHz)), defining any hearing loss as PTA(0.5-4 KHz) >25 dB HL. Presence of tinnitus was assessed by a positive response to a single question. Quality of life was measured using the Short Form 36-item Health Survey (SF-36). Each SF-36 dimension was scored from 0 (worst possible health state) to 100 (best possible health state). RESULTS: Prevalences of dizziness/vertigo, vestibular vertigo and non-vestibular vertigo were 36.2%, 10.0% and 14.2%, respectively. Of the dizziness/vertigo reports, 27.7% and 39.3%, respectively, were attributed to vestibular and non-vestibular vertigo. Tinnitus was associated with dizziness, odds ratio, OR, 1.99 (95% confidence interval, CI, 1.68-2.35). However, hearing loss was not associated with dizziness/vertigo. Participants reporting dizziness/vertigo had lower quality of life scores (P < 0.0001). Participants reporting vestibular vertigo were more likely than those with non-vestibular vertigo to report higher DHI scale scores or a greater handicap. CONCLUSION: Our findings highlight the burden imposed by dizziness, indicating dizziness/vertigo are important public health care issues.

K(+) currents produce P(1) in the RW CAP: evidence from DC current bias, K(+) channel blockade and recordings from cochlea and brainstem.

Tone-burst-evoked compound action potentials (CAP) from the guinea pig round window (RW) are altered by DC current injection through the RW. The CAP waveform consists of a series of interleaved negative and positive peaks (N(1), P(1), N(2), P(2) etc.) of decreasing amplitude. During positive DC current injection (around +50 microA) the positive peaks are depressed substantially and there is an overall negative baseline shift of the waveform following the N(1). Negative current injection (around -50 microA) increased the positive peaks, in particular P(1), and produced an overall positive baseline shift following the N(1) peak. Results support our hypothesis that the first and dominant N(1) peak in the RW CAP is due to depolarising Na(+) currents into the primary afferent dendrites and axons within the cochlea, and that the P(1) potential is largely due to the exit of the hyperpolarising K(+) currents in the same cells. We have reached this conclusion on the basis of the sign and latency of the N(1) and P(1) components at the RW, beneath the myelin layers around the spiral ganglion cells, at the internal auditory meatus (IAM) within the brain case, and on the basis of the differential susceptibility of the various peaks to perfusion of lidocaine in the cochlear nucleus, sectioning of the cochlear nerve at the IAM, application of the K(+) channel blockers 4-amino-pyridine and tetraethylammonium within the cochlea, and DC current biasing at the RW.

Transient focal cooling at the round window and cochlear nucleus shows round window CAP originates from cochlear neurones alone.

We have measured the compound action potential (CAP) evoked by very brief high-frequency tone-bursts (20 kHz, 1/4 ms) at the round window (RW) and at the surface of the cochlear nucleus (CN) in guinea pigs before, during and after a localised chilling of either the cochlea or CN, with a non-toxic 'freeze spray'. CN chilling almost abolished the negative-going component of the CAP measured in the CN (generated by the CN and here called the cochlear nucleus response or CNR), leaving a positive-going localised response from the cochlear neurones as they leave the internal auditory meatus. Within 3 min, the CNR recovered to control values. During that time, the N(1) component of the RW CAP was slightly increased and the P(1) was larger, even though the CNR was abolished, indicating that the P(1) was not due to electrotonic spread of current from the CN. The N(2) and successive peaks at the RW were also abolished, but returned after 30 s. When the cochlea was chilled, the RW CAP was initially reduced in amplitude, presumably due to a drop in the number of cochlear neurones spiking in response to sound, but recovered within 3 min to be larger than the control waveform, with a more prominent N(1) peak which was delayed slightly, making the CAP more monophasic. At the same time, the CNR was smaller, presumably due to fewer cochlear neurones responding, but overall the CN CAP was altered little in waveshape. These experiments indicate that that RW CAP is generated almost solely by cochlear neurones. We also suggest that some of the changes in the RW CAP during the chills were due to changes in the firing of the lateral olivo-cochlear system of efferent neurons.

Determinants of the spectrum of the neural electrical activity at the round window: transmitter release and neural depolarisation.

In this paper we summarise the changes we have observed in the electrical activity at the round window (RW) of guinea pigs during transient cooling of the RW or cochlear nucleus (CN), transient hypoxia, low frequency acoustic biasing, ablation of the CN, and DC current injection into the basal cochlear turn. We have measured the compound action potential (CAP), the spectrum of the average CAP waveform (SAW) evoked by brief tone-bursts, and the spectrum of the neural noise (SNN). We discuss how the changes we have observed can be understood in terms of changes in transmitter release from inner hair cells (that controls stochastic neural firing), or changes in the membrane potential of the primary afferent neurones (that controls the neural firing waveshape and the spectral content of the SAW and SNN). We note that changes in sound intensity produce a simple increase in the stochastic release of transmitter from inner hair cells, without much change in the waveform of the neural response, but manipulations of the auditory brainstem, cooling and current injection all appear to alter neural firing rate and the neural response waveform, producing a baseline shift in the CAP and changes in 1000 Hz peak and low frequency content of the SAW and SNN. We also discuss the use of the CAP, SAW and SNN as an indication of cochlear and auditory brainstem neural activity.

The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes.

The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes, was examined. Exponential or stationary preconditioned cultures were heat shocked and survivor numbers estimated using selective and overlay/resuscitation recovery techniques. The results indicate that prior heat shock induced increased heat resistance in both micro-organisms to higher heat treatments. Heat-shocked cells of each micro-organism were able to survive much longer than non-heat-shocked cells when heated at 55 degrees C. The size of the change in heat resistance between heat-shocked and non-heat-shocked cells was greatest for exponential cultures (X:X). Results indicate that the overall relative thermal resistance of each pathogen was dependent on cell growth phase. Stationary cultures (S:S) were significantly (P < 0.01) more thermotolerant than exponential cultures (X:X) under identical processing conditions. Under most conditions, the use of an overlay/resuscitation recovery medium resulted in higher D-values (P < 0.05) compared with a selective recovery medium.

Thermal inactivation of Listeria monocytogenes and Yersinia enterocolitica in minced beef under laboratory conditions and in sous-vide prepared minced and solid beef cooked in a commercial retort.

D-values were obtained for Listeria monocytogenes and Yersinia enterocolitica at 50, 55 and 60 degrees C in vacuum-packed minced beef samples heated in a laboratory water-bath. The experiment was repeated using vacutainers, which allowed heating of the beef to the desired temperature before inoculation. D-values of between 0.15 and 36.1 min were obtained for L. monocytogenes. Pre-heating the beef samples significantly affected (P < 0.05) the D60 value only. D-values for Y. enterocolitica ranged from 0.55 to 21.2 min and all the D-values were significantly different (P < 0.05) after pre-heating. In general, the D-values obtained for core inoculated solid beef samples were significantly higher (P < 0.05) than those generated in minced beef when heated in a Barriquand Steriflow commercial retort.

Synergistic effect of heat and sodium lactate on the thermal resistance of Yersinia enterocolitica and Listeria monocytogenes in minced beef.

The effect of sodium lactate (NaL) (0, 2.4 or 4.8%), in heating and recovery media, on Yersinia enterocolitica and Listeria monocytogenes numbers recovered from minced beef heated at 55 degrees C, was examined. Survivors were enumerated on selective media at pH 5.7/7.4 (Y. enterocolitica) or pH 5.7/7.2 (L. monocytogenes). Recovery of the organisms depended on the pH and NaL levels in the recovery medium. The heat resistance of Y. enterocolitica (P < 0.001) and L. monocytogenes (P < 0.01) decreased as the concentration of NaL in the minced beef increased from 0 to 2.4% or 4.8%. The thermal destruction of pathogens in foods processed using mild temperatures may be enhanced by the addition of 2.4% NaL.

Evaluation of the effectiveness and efficiency of two stimulus prompt strategies with severely handicapped students.

In this study we compared the effectiveness and efficiency of two treatment packages that used stimulus prompt sequences and task analyses for teaching community living skills to severely handicapped students. Four severely and multiply handicapped students were trained to perform four tasks: (a) making toast, (b) making popcorn, (c) operating a clothes dryer, and (d) operating a washing machine. Following baseline, each student was exposed to two types of training procedures, each involving a task analysis of the target behavior. Training Procedure 1 (Traditional) utilized a least-to-most restrictive prompt sequence. Training Procedure 2 (Prescriptive) utilized ongoing behavioral assessment data to identify discriminative stimuli. The assessment data were used to prescribe instructional prompts across successive training trials. Performance on the tasks was evaluated within a combination multiple baseline (across subjects) and probe (across tasks) design. Training conditions were counterbalanced across subjects and tasks. Results indicated that both training procedures were equally effective in increasing independent task acquisition for subjects on all tasks; however, the prescriptive procedure was the more efficient procedure.

Teaching selected microcomputer skills to retarded students via picture prompts.

Five retarded students were taught to use picture prompts to help them access and terminate a microcomputer program. Training was provided within a multiple baseline format. Posttesting (picture prompts without feedback), and a return to baseline were later conducted for both the training program and an untrained (generalization) program. The results indicate that the program was successful in teaching the microcomputer skills to the students. In addition, all students were able to maintain their skills over a 7-day interval in which they did not have access to the microcomputer.