Neurophysiological evaluation of segmental motor neuron function of the thoracic cord in chronic SCI.

STUDY DESIGN: Pilot study. OBJECTIVES: The aim of the study was to develop a neurophysiological method to diagnose the cranial as well as the caudal level of a complete thoracic spinal cord injury (SCI) with higher precision than today's protocols. SETTING: SCI unit Karolinska University Hospital, Stockholm, Sweden. METHODS: Bipolar needle electromyography was recorded in intercostal spaces of five patients with chronic, complete thoracic SCI. Tests were performed during rest, during voluntary activation and during activation of lower body spasticity. Magnetic resonance imaging (MRI) was performed in each patient according to a protocol optimized for imaging near metal implants. RESULTS: Three distinct patterns were found in each patient. Above the lesion we found voluntary activated, normal motor unit potentials (MUPs). At the neurological level and a varying number of segments below, denervated intercostal segments with fibrillation potentials and positive sharp waves appeared. Below the neurological level, normal MUP activated in concert with lower body spasticity was found. The number of denervated segments showed a significant correlation to the length of spinal cord discontinuity on MRI (r=0.97, P<0.05). CONCLUSION: Intercostal neurophysiology in combination with MRI optimized for imaging near metal implants can be used to determine the extent of a chronic complete thoracic SCI, both anatomically and functionally. The described method increases the sensitivity to detect delicate neurological changes related to the dynamic of the pathology that follows SCI and may be useful in analyzing outcome in clinical trials.

Catalytic galactose oxidase models: biomimetic Cu(II)-phenoxyl-radical reactivity.

Biomimetic functional models of the mononuclear copper enzyme galactose oxidase are presented that catalytically oxidize benzylic and allylic alcohols to aldehydes with O2 under mild conditions. The mechanistic fidelity between the models and the natural system is pronounced. Modest structural mimicry proves sufficient to transfer an unusual ligand-based radical mechanism, previously unprecedented outside the protein matrix, to a simple chemical system.

Phase determination by multiple-wavelength x-ray diffraction: crystal structure of a basic "blue" copper protein from cucumbers.

A novel x-ray diffraction technique, multiple-wavelength anomalous dispersion (MAD) phasing, has been applied to the de novo determination of an unknown protein structure, that of the "blue" copper protein isolated from cucumber seedlings. This method makes use of crystallographic phases determined from measurements made at several wavelengths and has recently been made technically feasible through the use of intense, polychromatic synchrotron radiation together with accurate data collection from multiwire electronic area detectors. In contrast with all of the conventional methods of solving protein structures, which require either multiple isomorphous derivatives or coordinates of a similar structure for molecular replacement, this technique allows direct solution of the classical "phase problem" in x-ray crystallography. MAD phase assignment should be particularly useful for determining structures of small to medium-sized metalloproteins for which isomorphous derivatives are difficult or impossible to make. The structure of this particular protein provides new insights into the spectroscopic and redox properties of blue copper proteins, an important class of metalloproteins widely distributed in nature.

High-resolution XANES studies on vanadium-containing haloperoxidase: pH-dependence and substrate binding.

High-resolution X-ray absorption vanadium K-edge spectra were recorded for samples of vanadium-containing bromoperoxidase from the brown alga, Ascophyllum nodosum, at pH 9, 7, 5 and 4, as well as for enzyme samples containing the substrates, hydrogen peroxide and bromide. The well-resolved features of the XANES spectra are discussed. The pH-dependence of the structure of the active site has been studied revealing no significant change of the absorption features. We were able to detect an interaction of H2O2 with the vanadium site of the bromoperoxidase using XAS spectroscopy, whereas addition of bromide causes no energy shift of the XANES spectrum. The possible role of vanadium during the enzymatic reaction is discussed on the basis of our results.

Hypersensitivity to electricity: working definition and additional characterization of the syndrome.

Those who believe that electric appliances trigger adverse symptoms have coined the label hypersensitivity to electricity. Scientific research has not been able to identify a direct link between electromagnetic fields and symptoms, and no diagnostic criteria exist. Groups with reported hypersensitivity are very heterogeneous. A need exists for an operational working definition and improved characterization of groups. We report an investigation of symptoms and risk indicators associated with reported hypersensitivity to electricity-based on a survey at a high-technology, multinational telecommunications corporation. Comparisons are also made with patients referred to a university department of occupational and environmental health. No association was found between specific psychosocial work characteristics nor personal traits and hypersensitivity to electricity. We present skin and neurovegetative symptom indices. Results indicate that skin, and not neurovegetative symptoms, characterize the syndrome, at least during the first years of illness. For characterization, we propose a set of dimensions, including triggering factors, behavior, and duration of symptoms.

Problems related to shift work. A field study of Swedish railroad workers with irregular work hours.

A group of 132 engineers from the north of Sweden was included in the study. A subsample of about 50 subjects was selected for further laboratory investigations during a light and warm summer period and a dark and cold winter period. The mean for the hours of sleep noted on the sleep records was significantly lower for night work than for day work. The amount of sleep during night work was significantly less during the light period than during the dark period as was the amount of sleep during the day off. Body temperature measured during work followed a daytime pattern and had a low amplitude. Potassium excretion and the blood levels of cortisol displayed a stable circadian rhythm with a daytime pattern. Many environmental factors made the results of catecholamine data difficult to interpret. The frequency of reported peptic ulcers was higher in the engineer group than in some other groups.

Long-term exposure to electric fields. A cross-sectional epidemiologic investigation of occupationally exposed workers in high-voltage substations.

In the present epidemiologic study, 53 workers with a long-term (more than five years) exposure to the electric field of 400 kV substations were examined and compared with a matched reference group of 53 nonexposed workers from the same power companies. Matching variables included age, geographic location and employment time. The aim of the study was to investigate the possibility of persistent, chronic health effects in the exposed group as a consequence of exposure. The investigation indluded the nervous system (neurasthenic symptoms, psychological tests, electroencephalography), the cardiovascular system (symptoms, blood pressure, electrocardiography), and the blood (hemoglobin, red blood cells, reticulocytes, white blood cells including differential count, thrombocytes, sedimentation rate). Fertility was also assessed. The results showed no differences between the exposed and reference groups as a consequence of the long-term exposure to the electric fields. The groups differed, however, in that the exposed group had (a) consistently better results on the psychological performance tests, (b) a fewer number of children, especially boys, and (c) somewhat higher education. The differences in test results were due to the higher education among the exposed. The difference in number of children was also thought to be related to factors other than exposure since it was found to be present already 10--15 years before the work in 400 kV substations began.

Exposure to microorganisms, febrile and airway-obstructive symptoms, immune status and lung function of Swedish farmers.

A questionnaire was sent to 512 farmers, members of a local farmer's health association. Eighty were interviewed, and their serum precipitins and total serum immunoglobulin E (IgE) values were determined. Forty-five underwent extensive pulmonary function tests. On the basis of the clinical evaluation it was estimated that 19% of the farmers had experienced febrile reactions (fever and/or shivering) following exposure to organic dust, 50% of the 19% having been exposed within the last 2.5 years. Common causes were moldy grain, hay, and woodchips. The pulmonary function, gas exchange, and chest radiographs of those who had previously had febrile reactions were normal. Only 13% showed positive precipitin reactions in Ouchterlony double-diffusion tests. With more sensitive tests, positive precipitins were found in 59%, but they were negatively correlated with febrile episodes. Air samples collected during work with hay and grain on 21 farms contained between 10(7) to 2 X 10(9) microorganisms/m3. The highest values were associated with symptoms of alveolitis. Eleven percent of the farmers reported obstructive chest symptoms following exposure to organic dust. This group showed decreased pulmonary function and elevated serum IgE levels and included a high proportion of smokers and exsmokers. No correlation was found between febrile and obstructive reactions.

Effect of occupational exposure to organophosphorus insecticides on neuromuscular function.

Neurophysiological investigations and determinations of cholinesterase activity on plasma and erythrocytes were carried out on 11 Swedish spraymen exposed to bromophos, diazinon, dursbane, and malathion. Plasma cholinesterase activity was significantly reduced after work, while erythrocyte cholinesterase activity was unchanged. In none of the workers with a decreased plasma cholinesterase activity after work could any related acute neuromuscular disturbance be detected when the men were tested with repetitive nerve stimulation and with single fiber electromyography. Signs of subclinical neuropathy were present as a slight reduction in sensory conduction velocity and increased fiber density in some workers.

Cell response in bronchoalveolar lavage fluid after sulfur dioxide exposure.

Environmental chamber exposure and bronchoalveolar lavage (BAL) were used to study the dose-response relationship between short-term exposure to sulfur dioxide (SO2) and inflammatory reactions in the human lung as reflected in BAL fluid. Healthy subjects were exposed to 10, 13, 20, or 30 mg/m3 for 20 min. BAL was performed several weeks preexposure and 24 h postexposure. Mast cells, lymphocytes, lysozyme positive macrophages, and the total number of macrophages were significantly increased after SO2 exposure. A dose-dependent increase in the cell response in BAL fluid was observed after exposure to 10-20 mg/m3, but no further increase was detected after 30 mg/m3. Inflammatory cell response was found in BAL fluid at SO2 levels that occur in industrial indoor environments worldwide, and cell response to SO2 was also seen below the short-term exposure limit of Sweden and many other countries (13 mg/m3).

Can traditional epidemiology detect cancer risks caused by occupational exposure to pesticides?

In order to investigate the possible relationship between cancer and occupational exposure to pesticides, we reviewed the latest literature of the epidemiological studies in this area coming to the conclusion that, while several studies indicate a link between certain pesticides and certain tumors, this information is still insufficient, and further research on the health consequences of exposure to pesticides is needed. Moreover, provided there is a risk, it is often too limited to be detected by available epidemiological techniques. Therefore, in addition to the epidemiological studies, the development of new biology, gene technology and medical biotechnology methods may significantly enhance the specificity of the epidemiological studies. Thus, the fusion of molecular biology and epidemiology into molecular epidemiology may provide more specific methods for monitoring the occupational dependent carcinogenic risk of individuals and groups.

Exposure to formaldehyde: effects on pulmonary function.

Forty-seven subjects exposed to formaldehyde (mean air concentration 0.45 mg/m3) and 20 unexposed subjects, all of whom were employed at a carpentry shop, were studied with regard to symptoms and pulmonary function. Symptoms involving eyes and throat as well as chest oppression were significantly more common in the exposed subjects than in the unexposed controls. Spirometry and single breath nitrogen washout were normal Monday morning before exposure to formaldehyde. A reduction in forced expiratory volume in 1 sec by an average of 0.2 L (P = .002), percent forced expiratory volume by 2% (P = .04), maximum midexpiratory flow by 0.3 L/sec (P = .04) and an increase in closing volume in percentage of vital capacity by 3.4% (P - .002) were seen after a day of work and exposure to formaldehyde, suggesting bronchoconstriction. Smokers and nonsmokers displayed similar changes in spirometry and nitrogen washout.

Exposure, lung function, and symptoms in car painters exposed to hexamethylendiisocyanate and biuret modified hexamethylendiisocyanate.

Individuals who paint cars often complain to doctors about respiratory problems. Car painters are exposed to isocyanates, especially hexamethylendiisocyanate (HDI), and biuret modified HDI (HDI-BT). The mean exposure to HDI-BT was 115 micrograms/m3 in the air (range 10-385 micrograms/m3), which exceeds the time-weighted Swedish threshold level of 90 micrograms/m3. Exposure to HDI was about 1.0 microgram/m3 with brief peaks. This study investigated the effect of HDI and HDI-BT on lung function and included two control groups: (1) car platers, exposed to the same solvents and grinding dust as car painters, but not to isocyanates, and (2) car mechanics (controls), not exposed to the mentioned agents. Car painters and car platers were compared to car mechanics on Monday before work. Acute effects of car painting were tested by comparing the lung function values on Monday morning with those on Friday afternoon. Pulmonary function was evaluated by means of spirometry and a single breath nitrogen washout. Spirometry in painters and platers did not differ from that in controls, i.e., car mechanics. Closing volume in relation to vital capacity (CV%) was increased in car painters, suggestive of a "small airways disease" on Monday before work and tended to increase during a work week. Car platers did not differ from controls.

The effect of supplementary antioxidant therapy in patients who report hypersensitivity to electricity: a randomized controlled trial.

CONTEXT: Hypersensitivity to electricity is a proposed environmental illness of unknown etiology. Patients report a variety of symptoms that they relate to electric equipment. The afflicted individuals suffer from ill health. Many interventions have been tried but, to date, there is no one specific treatment that has been proven superior to other remedial actions. In general, there is a lack of controlled prospective studies. OBJECTIVE: To test the hypothesis that antioxidant therapy reduces symptoms and improves health in patients reporting hypersensitivity to electricity. DESIGN: Randomized, double-blind, crossover, placebo-controlled study. SETTING: Patients referred to the Environmental Illness Research Centre, Stockholm County Council. PATIENTS: Sixteen patients reporting hypersensitivity to electricity. INTERVENTION: Antioxidant supplementation (vitamins C and E, selenium). MAIN OUTCOME MEASURES: Self-reported symptoms and reported degree of hypersensitivity to electricity, serum levels of uric acid and diphenylpycrylhydrazyl (DPPH). RESULTS: The results indicated no significant differences in reported symptoms, reported hypersensitivity to electricity, or oxidative status in serum between periods of antioxidant and placebo treatments. Serum levels of DPPH and uric acid showed no correlation with the reported degree of symptoms or hypersensitivity to electricity. CONCLUSIONS: The study did not show any beneficial effect of antioxidant supplementation for patients reporting hypersensitivity to electricity. The results do not support the hypothesis that oxidative stress is a major contributor to ill health in patients who report hypersensitivity to electricity.