Levels of metals in hair of young children as an indicator of environmental pollution

In 1982 the levels of lead (Pb), cadmium (Cd), vanadium (V), copper (Cu), and selenium (Se) were determined in hair of 231 four- to five-year-old children. The objective was to explore the feasibility of using metal-in-hair levels in groups of children as an indicator of environmental pollution. The study was carried out in four areas, which were assumed to differ in ambient pollution by metals. A questionnaire on personal data, socioeconomic status, intake of beverages, and life-style was completed by the parents. The metal-in-hair levels covered a large range. The variables pertaining to location together with sex, presence of a garden, and drinking of coffee and/or tea explained 32% of the variance of Pb, 24% of the variance of Cd, and 21% of the variance of V. The total variance explained by all measured questionnaire items was at best 38%. The location was the most important factor. Cu and Se levels did not differ between the locations.     

An alternative method of nitrous oxide delivery into a minimal-flow circle breathing system

We have sought to define a way in which nitrous oxide can be safely and universally used at minimal to low flows by utilising a circle system with a controlled leak provided by a standard gas analyser sampling line and a fresh gas supply of 50% nitrous oxide in oxygen, entering from a trunk interposed between the ventilator and the circle system. Although preliminary calculations suggested that this arrangement was likely to work, it was found that 13 of 23 patients studied prospectively developed an inspired oxygen fraction below 0.3. We conclude that, although this arrangement provides a new means of introducing nitrous oxide into the circle breathing system, it does not appear inherently safer or more convenient than the conventional route.     

Atherosclerosis--multi-organ involvement the rule rather than the exception

Atherosclerosis is a systemic disorder and significant lesions often occur in organ systems other than the symptomatic area. Three groups of patients, those admitted to hospital with either coronary artery disease, carotid artery stenosis or peripheral vascular disease, were examined for concomitant atherosclerotic lesions. Non-invasive tests, namely duplex scanning of the carotid arteries, arm ergometer exercise testing, and segmental pressure of the limbs, were used during evaluation. A clear association between ischaemic heart disease, carotid artery stenosis and femoropopliteal disease was found. Women appear to be more prone to multi-organ involvement than men; their higher average age on admission to hospital is a possible explanation for this in some cases, but not all.     

Motion sickness--vestibular habituation with the centrifuge

People who are prone to motion sickness have a directional preponderance of nystagmus to the left. Centrifuging will change this preponderance to the right in most people, and at the same time reduce their tendency towards motion sickness but only with regard to air travel.     

Mental retardation and parental occupation: a study on the applicability of job exposure matrices.

In a case-referent study on mental retardation and parental occupation, the applicability of job exposure matrices for the identification of risk factors was evaluated. The parents of 306 mentally retarded children (cases) and 322 referents were interviewed about their occupational activities in the pregnancy period. Detailed occupational histories were obtained that were compared with exposures generated by two different job exposure matrices. The agreement between interview and matrices was low: the sensitivity ranged from 17.9% to 32.4% and the percentages of false positive exposures from 66.7% to 96.0%. By means of the interview, significantly increased odds ratios (ORs) were found for exposure of the mother in late pregnancy to radiation (OR = 9.3), mercury (OR = 8.7), organic solvents (OR = 1.7), hair cosmetics and dyes (OR = 3.7), paint (OR = 2.7), hexachlorophene/phenylphenol (OR = 3.1), antibiotics (OR = 2.9), and dust (OR = 2.2) and for working with copying machines (OR = 3.0) or in occupations with poor climatological circumstances and permanent contact with people. The last was confirmed by the British matrix (OR = 1.7). Otherwise, most of the mentioned associations were missed by the job exposure matrices. Therefore, these matrices were not considered to be applicable in this particular study, nor in most other reproductive epidemiological studies in view of their general properties and limitations.     

Morphometric analysis to detect suspected myocardial disease. A pilot study

Myofibres in the normal left ventricle (LVs) of 24 healthy young accident victims and the diseased LVs of 10 subjects who died from constrictive pericarditis or congestive (African) cardiomyopathy were subjected to morphometric evaluation. Each myofibre was represented by a pair of measurements: cross-nuclear fibre (FD) and nuclear (ND) diameters. Using a VIDS image analyser interfaced with a light microscope, 150 paired measurements were determined for each of the 34 specimens. The bivariate relationship between FD and ND for each group of specimens were expressed as linear regressions. The limits for the group distribution of normal specimen FD/ND means were calculated and graphically depicted in the form of an ellipse. Disease specimens were plotted for comparison. Of the normal specimens, 23/24 FD/ND coordinates fell within the "normal' ellipse whereas the altered relationship between FD and ND in pathological myocardia caused all 10 specimen means to be plotted outside the ellipse and their regression lines to be displaced from normal. It is suggested that the normal data define the morphometric parameters of LV myofibres in healthy hearts and create a graphic standard by which myofibre pathology in hearts suspected of disease can be detected.     

Use of PCR for Diagnosis of Post-Kala-Azar Dermal Leishmaniasis

Microscopy and PCR were compared for use in the diagnosis of post-kala-azar dermal leishmaniasis (PKDL) in 63 patients. Aspirates of lymph nodes (samples from 52 patients), skin (23 samples), and bone marrow (18 samples) were used. For 11 patients lymph node aspiration could be repeated 6 months after they recovered from PKDL. During active PKDL, PCR was positive for 42 of 52 (80.8%) lymph node aspirates and 19 of 23 (82.7%) skin aspirates, whereas microscopy was positive for only 9 of 52 (17.3%) lymph node aspirates and 7 of 23 (30.4%) skin aspirates. PCR was always positive when parasites were seen by microscopy. When the results obtained with lymph node and skin aspirates from the same patient (n = 16) were compared, there was complete agreement. Bone marrow samples were negative by microscopy and PCR for 16 patients and positive by both methods for 1 patient; for one sample only the PCR was positive. PCR confirmed the co-occurrence of visceral leishmaniasis and PKDL in one patient and confirmed the suspicion of this co-occurrence in the other patient. After recovery, no parasites were found by microscopy, but 2 of 11 (18.2%) samples were still positive by PCR. Thirty negative controls were all found to be PCR negative, and 15 positive controls were all PCR positive. Cross-reactions with Mycobacterium leprae could be ruled out. In conclusion, PCR with inguinal lymph node or skin aspirates is suitable for confirming the clinical diagnosis of PKDL. In some patients, lymph node aspirates are probably preferred because aspiration of material from the skin may leave scars.     

Immunotherapy of mammary adenocarcinoma metastases in C3H/HeN mice with chronic administration of cyclo-oxygenase inhibitors alone or in combination with IL-2

In this study the efficacy of treatment of two cyclo-oxygenase inhibitors, ibuprofen (Ibu) and indomethacin (Indo), are compared in the immunotherapy of metastasis designed to reverse prostaglandin E₂ (PGE₂)mediated inactivation of interleukin-2 (IL-2)-dependent host killer cell lineages. These agents were tested either alone for the prevention of metastasis or in combination with IL-2 for the eradication of established metastasis. C3H/HeN mice were placed on chronic oral Ibu (CIbT; 200 and 600 ,g/ml of water) or Indo (CIT; 10 g/ml) 5 days after s.c. transplantation of 5 × 10⁵ metastatic C3L5 mammary carcinoma for the prevention of spontaneous lung metastases. They showed intolerance to Indo at a dosage of 14 g/ml, which was well tolerated by other mouse strains in previous studies, but tolerated the Ibu dosages used. Control and treated mice were killed on day 30 to score metastatic lung colonies, to evaluate killer activity in splenocytes against natural killer (NK)-sensitive YAC-1 lymphoma or NK-resistant C3L5 adenocarcinoma and 8911 lymphoma targets, and to phenotype the surface markers of killer cells. CIbT and CIT alone at the above dosage significantly reduced the number of lung colonies, retarded local tumor growth and restored NK activity of splenic killer cells expressing AGM-1⁺, Thy-1^–, Lyt-2^– phenotype. To treat established lung metastasis, mice bearing 15-day C3L5 transplants were given CIbT or CIT alone or in combination with two 4-day rounds (days 20–23, 31–34) of IL-2 (15 000 Cetus units, i.p. every 8 h) and were killed on day 35 to score lung colonies and characterize splenic killer cells. CIbT or CIT alone reduced the number of spontaneous lung metastases and restored anti-YAC-1 killer function of splenocytes with NK-like phenotype (AGM-1⁺, Thy-1^–, Lyt-2^–); some anti-C3L5 killer function was also generated in the high dose Ibu group and the killer cell showed AGM-1⁺, Thy-1⁺ and Lyt-2⁺ phenotype. Combined therapies with CIbT or CIT plus IL-2 were more effective in reducing metastases and promoting killer cell function, the best results being achieved with high dose Ibu + IL-2. All killer cells expressed AGM-1 and Thy-1. In addition, C3L5 killer cells also expressed Lyt-2, suggesting T-cell stimulation. PGE₂ synthesis in the host was inhibited by at least 50% in mice subjected to CIbT or CIT. Thus, Ibu proved to be an excellent substitute for Indo in preventing metastasis and NK cell activation when given alone, and also in ameliorating established metastasis and activating lymphokine-activated killer cells when combined with IL-2.     

Adaptive spatial filtering of multichannel surface electromyogram signals

Spatial filtering of surface electromyography (EMG) signal can be used to enhance single motor unit action potentials (MUAPs). Traditional spatial filters for surface EMG do not take into consideration that some electrodes could have poor skin contact. In contrast to the traditional a priori defined filters, this study introduces an adaptive spatial filtering method that adapts to the signal characteristics. The adaptive filter, the maximum kurtosis filter (MKF), was obtained by using the linear combination of surrounding channels that maximises kurtosis. The MKF and conventional filters were applied to simulated EMG signals and to real EMG signals recorded with an electrode grid to evaluate their performance in detecting single motor units. The MKF was compared with conventional spatial filtering methods. Simulated signals, with different levels of spatially correlated noise, were used for comparison. The influence of one electrode with poor skin contact was also investigated. The MKF was found to be considerably better at enhancing a single MUAP than conventional methods for all levels of spatial correlation of the noise. For a spatial correlation of 0.97 of the noise, the improvement in the signal-to-noise ratio, where a MUAP could be detected, was at least 6 dB. With a simulated poor skin contact for one electrode, the improvement over the other methods was at least 19 dB.