Effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts: a nested case-control study.

BACKGROUND: Exposure reduction has proven to be effective in the prevention of occupational asthma. Few data are available on the effectiveness of secondary prevention programs, including medical examinations and removal of workers from exposure sources after detecting symptoms or signs indicative of a beginning disease. OBJECTIVE: We sought to assess the effectiveness of a medical surveillance program in workers with exposure to platinum salts. METHODS: A nested case-control study was performed in 14 workers of a catalyst production plant whose skin prick test (SPT) responses to platinum salt converted from negative to positive during a 5-year prospective cohort study with yearly medical examinations and 42 matched control subjects from the plant who did not experience SPT response conversion. With the exception of 2 subjects, the workers showing SPT response conversion were removed completely from exposure sources and followed for up to 42 months. RESULTS: Work-related new symptoms were reported by 9 of the 14 subjects, and new symptoms without relation to work were reported by 3 subjects at the time of SPT response conversion. Symptoms were not accompanied by a change in FEV(1) or bronchial responsiveness to histamine. Symptoms resolved after transferral, but occasional shortness of breath or wheeze persisted in 4 subjects. SPT reactions decreased or became negative in all workers after complete removal but remained unchanged in a craftsman with ongoing occasional exposure to contaminated materials. CONCLUSION: Although no randomized intervention was performed, this study proves the effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts.

Exposure-effect relationship of platinum salt allergy in a catalyst production plant: conclusions from a 5-year prospective cohort study.

BACKGROUND: There is a high incidence of occupational asthma and rhinitis caused by platinum (Pt) salts in precious-metal refineries. OBJECTIVE: We sought to assess exposure to Pt salts and the incidence of Pt salt allergy in a catalyst production plant. METHODS: A 5-year prospective cohort study was performed in 159 catalyst production workers (94.6% of recruited), 50 craftsmen (92. 6% of recruited), and 66 control subjects (76.7% of recruited) at yearly intervals. Subjects were assigned to exposure categories of high levels of Pt (n = 115), persistently low levels of Pt (n = 51), intermittently low levels of Pt (n = 61), or no Pt (n = 48) after the initial survey according to job title and job location. Skin prick test conversion from a negative response to a 4 mm or larger wheal response with a 10(-2) mol/L hexachloroplatinic acid solution was chosen as the outcome variable. RESULTS: Exposure assessment of airborne Pt and Pt in the serum of workers demonstrated clear differences between exposure categories. The threshold limit value of 2 microg/m(3) for soluble Pt was exceeded in 3 (4%) of 78 measurements. Thirteen subjects assigned to high exposure showed skin test conversion, and new allergic symptoms were associated with exposure. Among the high-exposure category, the incidence rate of skin prick test conversion was 5.9 per 100 person-years for newly employed subjects (n = 79) and 2.1 per 100 person-years for those who had already been employed at the time of the initial survey (n = 36). A predicting factor for skin test conversion in highly exposed subjects was smoking status (relative risk, 3.9; 95% confidence interval, 1.6-9.7) but not atopy or bronchial hyperresponsiveness. CONCLUSION: Sensitization to Pt salts may develop in workers of catalyst production plants. Both the exposure to Pt salts and the incidence of Pt salt allergy were lower compared with reported data from precious-metal refineries.

Outcome of occupational asthma due to platinum salts after transferral to low-exposure areas.

OBJECTIVE: To assess the health effects of transferral to low-exposure jobs on subjects with occupational asthma (OA). METHODS: We performed a cross-sectional survey of 83 workers in 2 platinum (Pt) refineries and 2 catalyst production plants, all with diagnosed OA due to Pt salts. In all, 9 workers (group A; 11%) continued to be exposed at the time of examination, 16 subjects (group B; 19%) had been transferred to other workplaces within the production building, 39 subjects (group C; 47%) had been transferred to areas outside the building but inside the plant, and 19 subjects (group D; 23%) had left the plant. The median period from transferral to examination was 54 months (lower quartile 23 months, upper quartile 84 months, n = 74). Symptoms, skin-prick tests (SPT) with environmental allergens and Pt salt, total serum IgE, lung function, and bronchial hyperresponsiveness were assessed by standard procedures. RESULTS: Asthma symptoms were reported by all subjects in the production area but by only 37 of 74 subjects (50%) after transferral, with no difference being found between groups B, C, and D. Both the proportion of subjects sensitized to Pt salts (100%, 88%, 67%, and 42% in groups A, B, C, and D, respectively) and the degree of sensitization were associated with exposure (P < 0.0002). Total IgE was higher in group A as compared with groups B, C, or D (P < 0.002). There was no association between bronchial hyperresponsiveness and exposure. Although no univariate difference in FEV1 was found between the groups, regression analysis showed an association between FEV1 and exposure (P < 0.002). In all, 13 subjects demonstrated a predicted FEV1 value of <80% (22%, 6%, 10%, and 32% in groups A, B, C, and D, respectively). They were older (median 49 versus 37 years; P < 0.002) and had worked over longer periods in high-exposure areas in spite of symptoms (median 43 versus 10 months; P < 0.003). Fifteen subjects of groups C or D had been removed from areas B previously, eight of them due to respiratory symptoms. CONCLUSIONS: For the majority of subjects with OA due to Pt salts transfer to low exposure areas as defined in this study may not be associated with a more unfavorable outcome as compared with complete removal from exposure sources.

Reconstitution and characterization of the polynuclear iron-sulfur cluster in pyruvate formate-lyase-activating enzyme. Molecular properties of the holoenzyme form.

The glycyl radical (Gly-734) contained in the active form of pyruvate formate-lyase (PFL) of Escherichia coli is generated by the S-adenosylmethionine-dependent pyruvate formate-lyase-activating enzyme (PFL activase). A 5'-deoxyadenosyl radical intermediate produced by the activase has been suggested as the species that abstracts the pro-S hydrogen of the glycine 734 residue in PFL (Frey, M., Rothe, M., Wagner, A. F. V., and Knappe, J. (1994) J. Biol. Chem. 269, 12432-12437). To enable mechanistic investigations of this system we have worked out a convenient large scale preparation of functionally competent PFL activase from its apoform. The previously inferred metallic cofactor was identified as redox-interconvertible polynuclear iron-sulfur cluster, most probably of the [4Fe-4S] type, according to UV-visible and EPR spectroscopic information. Cys --> Ser replacements by site-directed mutagenesis determined Cys-29, Cys-33, and Cys-36 to be essential to yield active holoenzyme. Gel filtration chromatography showed a monomeric structure (28 kDa) for both the apoenzyme and holoenzyme form. The iron-sulfur cluster complement proved to be a prerequisite for effective binding of adenosylmethionine, which induces a characteristic shift of the EPR signal shape of the reduced enzyme form ([4Fe-4S]+) from axial to rhombic symmetry.

Effects of low-frequency magnetic fields on electrocortical activity in humans: a sferics simulation study.

A previously recorded electromagnetic impulse of natural origin, a 10 kHz-sferic, was simulated and presented to 20 subjects. The magnetic component of the signal with a maximum field amplitude of 50 nT and a duration of 500 microseconds was applied over a duration of 10 minutes with a pulse repetition rate that varied statistically between 7 and 20 Hz. After sferics exposure, an additional 20 minutes without treatment were recorded in order to examine possible prolonged effects of sferics stimulation. The control group (n = 20) received no treatment. As a dependent measure, electrocortical changes throughout the course of the experiment were determined by means of EEG spectral analysis and compared between the two groups. Sferics exposure provoked increases in alpha and beta power. The effect was present during stimulation and continued for 10 minutes after the end of treatment. A longer lasting influence of sferics exposure was displayed by subjects with a high degree in weather sensitivity, somatic complaints, and neuroticism, who continued to stay on an enhanced alpha power level until the end of registration (20 minutes after the end of exposure). With these results a general electrocortical sensitivity towards sferics as well as individual differences in sferics reactivity could be demonstrated.

A cross sectional study of chemical industry workers with occupational exposure to persulphates.

OBJECTIVES: Hair bleaches containing persulphates have been identified as the cause of occupational asthma in hairdressers. Also employees in persulphate production with occupational asthma have been described. It was the aim of this study to give an estimate of the prevalence of asthma due to persulphates in chemical workers with exposure to ammonium and sodium persulphate. METHODS: A cross sectional study was performed in 32 of 33 employees of a persulphate producing chemical plant. Eighteen of 23 workmen from the same plant with no exposure to persulphates were taken as controls. Also, information was collected from medical records of the seven subjects who had left the persulphate production for medical reasons since 1971. Data were recalled by a questionnaire, skin prick tests were performed with five environmental allergens, and ammonium and sodium persulphate (80 mg/ml). Specific immunoglobulin E (IgE) to the same environmental allergens as in the skin test, and total IgE were measured. Lung function and bronchial responsiveness to histamine were assessed by standard procedures. Workplace concentrations of ammonium and sodium persulphate were estimated by area and personal monitoring. The amount of persulphate was analysed as sulphur by inductively coupled plasma emission spectrometry. RESULTS: Work related rhinitis was reported by one subject with exposure to persulphates, conjunctivitis and bronchitis were reportedly related to work by two controls. There were no cutaneous reactions to persulphates in either group. Four non-atopic subjects exposed to persulphates, and two controls, one atopic and one non-atopic, were considered to be hyperresponsive to histamine. Three subjects exposed to persulphates with bronchial hyperresponsiveness (provocation dose of histamine causing a 15% fall in forced expiratory volume in one second (PD15 FEV1) < or = 1 mg) did not show variability in peak expiratory flow of > or = 20%, the rest refused peak flow measurements. None of the variables showed significant differences between the groups (P > 0.05). Six of the exworkers left because of work related contact dermatitis. Mean values for workplace concentrations of ammonium and sodium persulphate within the bagging plant were below 1 mg/m3, and the maximal concentrations were 1.4 mg/m3 and 3.6 mg/m3, respectively. CONCLUSION: Exposure to workplace concentrations of ammonium and sodium persulphate of about 1 mg/m3 in this chemical plant was not associated with a risk of occupational asthma.

Atmospheric electromagnetism: individual differences in brain electrical response to simulated sferics.

The living organism is constantly affected by natural electromagnetic influences covering a wide range of frequencies and amplitudes. One of these natural influences is represented by a phenomenon called atmospherics or sferics. Sferics are very weak electromagnetic impulses generated by atmospheric discharges (lightning). With a newly developed simulation system it was possible to reproduce a previously registered sferics signal and present it to 52 subjects while recording the electroencephalogram (EEG). The repeated application of this stimulus for ten minutes evoked a significant decrease in alpha power in parietal and occipital regions compared to the control condition without sferics presentation. Two constitutional factors were revealed as mediators of sferics effectiveness: the general physical condition of the subjects, and their neuroticism. Individuals with many somatic complaints and a high degree of emotional lability did not respond to the sferics stimulation. This absence of a response is interpreted as an adaptational deficit in reaction to variations in atmospheric parameters.

Aprotinin in open-heart surgery of infants and children using the heart-lung machine.

The purpose of this study was to evaluate a new approach to managing thrombohemorrhagic diathesis in infants and children undergoing extracorporeal circulation during open-heart surgery. Treatment consisted of administering vitamin K1 and aprotinin preoperatively as well as during bypass and after neutralization of heparin. Operative techniques were either surface-induced deep hypothermia and total circulating arrest or conventional bypass with mild-to-moderate hypothermia. At completion of the intracardiac repair, heparin was neutralized with protamine chloride (1:0.7-0.8). Complete bleeding and clotting studies were carried out in 122 patients before, during, and after the bypass procedure. Most of the infants, especially those with congenital cyanotic heart disease, had marked fibrinolysis and vitamin K1 deficiency preoperatively. All patients postoperatively exhibited fibrinolysis and proteolysis greatly exceeding normal values with increased bleeding tendency. The treatment significantly reduced blood loss and transfusion requirements.