Assessment of 'on-treatment platelet reactivity' and relationship with cerebral micro-embolic signals in asymptomatic and symptomatic carotid stenosis.

INTRODUCTION: The relationship between on-treatment platelet reactivity and cerebral micro-embolic signals (MES) is unknown, and has not been previously simultaneously assessed in asymptomatic and symptomatic carotid stenosis patients. METHODS: Consecutive eligible patients with ≥50% asymptomatic or recently symptomatic carotid stenosis (≤4weeks following TIA/ischaemic stroke) were recruited to this pilot study. Symptomatic patients were followed up to the 'late' phase (≥3months) following symptom onset or carotid intervention; longitudinal data were analysed from symptomatic patients with data available at both time-points. Platelet function/reactivity was assessed with the PFA-100® to measure collagen-ADP (C-ADP) and collagen-epinephrine (C-EPI) closure times in citrate-anticoagulated whole blood. Bilateral simultaneous 1-hour transcranial Doppler ultrasound (TCD) monitoring of the middle cerebral arteries was performed to classify patients as MES +ve or MES -ve. RESULTS: 31 patients with ≥50% asymptomatic and 46 with early symptomatic carotid stenosis or occlusion were included. 35 symptomatic patients were followed up to the late phase (23 following carotid intervention). Prevalence of 'high on-treatment platelet reactivity' (HTPR) on the C-EPI cartridge did not differ between asymptomatic and symptomatic patients overall, but was lower in 'symptomatic post-intervention' than asymptomatic patients on aspirin monotherapy (10% vs. 50%; p=0.03). The prevalence of HTPR on the C-EPI cartridge decreased between the early and late phases in symptomatic patients (63% vs. 34%; p=0.017), including those on aspirin monotherapy (p=0.016). There were no significant differences in HTPR status between asymptomatic vs. early or late symptomatic MES +ve or MES -ve patients. DISCUSSION: Carotid interventional treatment, presumably in combination with resolution of the acute phase response, may decrease the prevalence of HTPR in patients with recently symptomatic carotid stenosis over time. Preliminary subgroup analysis suggests that successful intervention may reduce the prevalence of aspirin-HTPR in symptomatic patients to lower levels than asymptomatic medically-treated patients on aspirin monotherapy. Larger, longitudinal studies are warranted to reassess the impact of more intensive secondary preventive treatment on ex vivo platelet function at different levels of shear stress in carotid stenosis patients.

Cross-sectional survey of workers exposed to aliphatic diisocyanates using detailed respiratory medical history and questions regarding accidental skin and respiratory exposures.

OBJECTIVES: To identify possible cases of occupational asthma and assess accidental skin and inhalation exposures to aliphatic diisocyanates. METHODS: Seventy-three employees from two plants, manufacturing or producing aliphatic diisocyanates, were surveyed using a detailed respiratory history questionnaire with additional questions on accidental skin and inhalation exposures. Further reviews of medical records and interviews were used to determine whether any of 15 employees with questionable responses had developed occupational asthma. RESULTS: No cases of occupational asthma were identified. Nevertheless, many employees reported occasional accidental unprotected skin exposures and/or detecting the odor of 1,6-hexamethylene diisocyanate or isophorone diisocyanate. CONCLUSIONS: Consistent with a previous study, no cases of occupational asthma were identified from exposure to 1,6-hexamethylene diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate), or their polyisocyanates even though many employees reported detection of odors (93%) or skin exposures (53%).

Trends in pulmonary function and prevalence of asthma in hexamethylene diisocyanate workers during a 19-year period.

OBJECTIVE: To identify if 1,6-hexamethylene diisocyanate (HDI) workers demonstrated an increased prevalence of occupational asthma or accelerated decline in pulmonary function. METHODS: Employees from two plants manufacturing or producing 1,6-HDI monomer and/or HDI polyisocyanates were matched to a control population by age, gender, race, and smoking status. A random coefficient regression analysis compared the decline in pulmonary function test values over time. Retrospective medical review was used to identify potential cases of occupationally induced asthma. RESULTS: No significantly accelerated annual decline in force expiratory volume after 1 second in the HDI exposure group compared to the matched control group was observed. No cases of adult onset asthma, beyond those present at time of hire, and no cases of occupational asthma were identified. CONCLUSIONS: This study provides support for the current American Conference of Governmental Industrial Hygienists threshold limit value time-weighted average of 5 ppb.