The structural organization of N-methyl-2-pyrrolidone + water mixtures: a densitometry, x-ray diffraction, and molecular dynamics study.

A combined approach of molecular dynamics simulations, wide angle X-ray scattering experiments, and density measurements was employed to study the structural properties of N-methyl-2-pyrrolidone (NMP) + water mixtures over the whole concentration range. Remarkably, a very good agreement between computed and experimental densities and diffraction patterns was achieved, especially if the effect of the mixture composition on NMP charges is taken into account. Analysis of the intermolecular organization, as revealed by the radial and spatial distribution functions of relevant solvent atoms, nicely explained the density maximum observed experimentally.

[Perception of stress in the nursing profession: study of the behavior of s-IgA]. / Percezione di stress nel settore infermieristico: studio sul comportamento delle s-IgA.

AIMS: To assess and compare self reported work stressors among emergency (PS) and medicine department (ME) nurses, and to investigate its relation with salivary IgA. METHODS: Fifty seven of 93 (61.2%) female PS and ME nurses participated in the study. The Italian version of NIOSH Job Stress Questionnaire was used to measure self perceived stress. ELISA methods were used to determine the salivary IgA. RESULTS: The scores of scales such as workload and conflict with co-workers were higher in PS (3.72 and 3.18) than in ME nurses (3.12 and 2.66). PS nurses had lower concentration rates of IgA (mean 123.3 microg/ml) than ME nurses (mean 221.49 microg/ml). Significant inverse correlations were observed between the scores of workload and conflict with co-workers and log IgA (respectively r -0.27 e -0.33, both p < 0.01). CONCLUSION: PS nurses showed significantly lower secretion rates of salivary IgA compared to ME nurses. Salivary IgA were inversely correlated with measured self reported work stressors.

[Anti-p53 antibodies as markers of carcinogenesis in exposures to vinyl chloride]. / Anticorpi anti-p53 come marker di cancerogenesi nella esposizione a cloruro di vinile.

The aim of the study was to estimate the possible use of plasma anti-p53 antibodies as marker premature of cancerogenesis. The study carried on 167 male subject exposed to vinyl chloride (CV) (cumulative concentration ranged from 4 to 2823 ppm) tested anti-p53 positive in 5 cases (3.9%), all distributed in the high exposure group (> 1000 ppm); No subject in the control group tested positive. There was a significant association. between cumulative VC exposure concentration (P < 0.002) and positive anti-p53 expression. In summary, the study support a significant relationship between plasma anti-p53 and VC only for heavy exposure. The authors assume the existence of a threshold limit to the effectiveness.

Periportal fibrosis and other liver ultrasonography findings in vinyl chloride workers.

AIMS: To investigate the presence of liver lesions and their relation with vinyl chloride monomer (VCM) exposure or other personal risk factors, in workers involved in the production of VCM and polyvinyl chloride (PVC). METHODS: A liver ultrasonography examination was conducted in 757 workers, some of whom had long standing service in the production of VCM and PVC. The study involved: assessment of individual past and present VCM exposure of each worker; collection of past personal health history, lifestyle and personal data; routine liver function tests; and liver ultrasonography. RESULTS: No cases of liver malignancies were detected. Angiomas and liver cysts were found with a frequency of occurrence within the expected range of the general population. The main findings consisted of hepatomegaly (34.7%), steatosis (31.8%), and periportal fibrosis (16.0%). A logistic regression analysis indicated that hepatomegaly and steatosis were associated with obesity and lipid metabolism disturbances and not with VCM exposure. Periportal fibrosis, in addition to constitutional or dietary factors, was shown to be associated with VCM exposure, but only when maximum exposure in the subject's history had been at least 200 ppm as a yearly average; no effects were observed at 50 ppm or below. CONCLUSIONS: Workers exposed to 200 ppm VCM for at least one year have a fourfold increased risk of developing periportal liver fibrosis. Liver ultrasonography is a suitable and important diagnostic test for the medical surveillance of vinyl chloride workers.

[Urinary and blood markers of internal mercury dose in workers from a chlorakali plant and in subjects not occupationally exposed: relation to dental amalgam and fish consumption]. / Indicatori urinari ed ematici di dose interna di mercurio in lavoratori di un impianto clorosoda e in soggetti non professionalmente esposti: relazione con gli amalgami dentali ed il consumo di pesce di mare.

OBJECTIVES: The aim of this paper was both to evaluate the internal dose of Hg in occupationally exposed workers (35 Chloralkali workers) compared to that of non occupationally exposed controls (40 workers of the same plant of Portotorres and 22 residents on the island of Carloforte, usual consumers of local fish, mostly tuna fish with relatively high Hg levels) and to assess the relevance of environmental and individual exposure factors linked to lifestyle, sea fish consumption and amalgam fillings. METHODS: All subjects filled out a questionnaire concerning the working history and lifestyle. The amalgam fillings area was measured by medical inspection using a standardised schedule attached to the questionnaire. Mercury in urine (HgU) was measured in all cases, while in a subgroup of our study total blood mercury (HgB) and its organic and inorganic component were also assessed. Furthermore, for 8 of the Carloforte group mercury in hair was also available. RESULTS: Values of urinary mercury excretion of the Chloralkali workers were significantly higher (median value of 15.4, range 4.8-35.0 micrograms/g creatinine, 94.3% of the cases having values > 5 micrograms/g creatinine) than those observed both among the reference group (median value of 1.9, range 0.4-5.6 micrograms/g creatinine, 12.5% of the cases having values a little greater than 5 micrograms/g creatinine) and among the residents in Carloforte (median value of 6.5, range 1.8-21.5 micrograms/g creatinine, 59.1% of the cases having values > 5 mcg/g creatinine). The HgU values observed in this group were in turn significantly higher than those of the non occupationally exposed workers living near Sassari (p = 0.03). Only in this last group were the HgU concentrations statistically significantly related to the extension of the amalgam fillings area (Pearson r = 0.53, p < 0.01). In the Carloforte group HgU was significantly related to the number of fish meal consumed per week (Pearson r = 0.48, p < 0.02). HgB (median value of 5.9, range 3.4-21.6 micrograms/l) as well as its inorganic component (median value of 2.4, range 1.8-4.6 micrograms/l) were significantly higher in the Chloralkali group compared to the other two groups. In all cases of the Carloforte group the ratio between the organic component and the total HgB was higher than 85%, while this ratio was significantly lower in the other two groups. The relationship between HgU and HgB was statistically significant, considering both total blood mercury and the inorganic and the organic components separately. A statistically significant relationship between the sea fish consumption per week and both total HgB (Pearson r = 0.82) and the organic component in this matrix (Pearson r = 0.84, p < 0.001) was observed among 16 non-occupationally exposed subjects. However, the significant relationship between organic blood mercury and sea fish consumption was almost entirely supported by the data observed in the Carloforte group. Total hair mercury levels analysed in 8 subjects of the Carloforte group were high (median value of 9.6, range 1.4-34.5 micrograms/g) and significantly related to sea fish consumption, and to both the individual Hg urinary excretion (Pearson r = 0.83) and to the organic component of blood mercury (Pearson r = 0.87). CONCLUSIONS: According to several experimental human and animal trials and to some recent studies on methylmercury toxicokinetic models, our results suggest that the organic compounds absorbed by usual sea fish consumption may be partially demethylated, increasing the inorganic Hg concentration in the kidney and consequently its urinary excretion, as was observed in the Carloforte group.

The effect of noise on serum and urinary magnesium and catecholamines in humans.

We have studied whether a short-term exposure to loud noise was able to modify urinary catecholamine excretion and serum concentration and urinary excretion of magnesium and other related electrolytes. In 25 healthy volunteers, blood and urine concentrations of magnesium, calcium, phosphorus and creatinine, and urinary catecholamines were measured before and after exposure to noise in an industrial plant. Samples were collected at 08:00 h on the day of the experiment and soon after noise exposure (at 20:00 h). Two further urine samples were collected the following day and 2 days after the experiment, always at 08:00 h in the morning. The sound energy average level was 98 dB(A), but peak levels reached 108 dB(A). Urinary catecholamines were determined by high-performance liquid chromatography. Serum magnesium and calcium were significantly increased after exposure to noise, whereas phosphorus displayed a similar but non-significant trend (P = 0.065). Multivariate analysis of variance (ANOVA) showed significant differences both among subjects (P < 0.001) and after exposure (P < 0.001). Adrenaline, noradrenaline and dopamine values were not significantly different after exposure to noise (P > 0.05). Urinary magnesium levels were significantly different across time (P = 0.017). Urinary calcium levels were not significantly different across time (P = 0.36). Urinary phosphate values were increased after exposure to noise (P = 0.007); urinary creatinine was not changed after exposure (P > 0.05). Our study shows that noise induces significant increases of serum calcium and magnesium, with a borderline increase of serum phosphorus; this in turn is reflected in a significantly increased urinary excretion of magnesium and phosphate after exposure, which lasts for the following 2 days. Urinary calcium and creatinine were not modified by noise. The difference in catecholamine values did not reach statistical significance. Thus, we failed to substantiate a significant correlation between catecholamine secretion and magnesium metabolism, as others had suggested.

Psychological factors and visual fatigue in working with video display terminals.

OBJECTIVES: To examine the part played by psychological factors in complaints about visual health reported by banking officers who work at video display terminals (VDTs). METHODS: Out of a population of 385 bank workers, a group of 212 subjects without organic visual disturbances (as determined by ophthalmological examination) who share a work environment and job duties was selected. Three questionnaires were administered to these subjects: (a) the NIOSH job stress questionnaire; (b) a questionnaire investigating subjective discomfort related to environmental and lighting conditions of the workplace; (c) a questionnaire on the existence of oculovisual disturbances. Correlation and multiple regression analyses were performed to examine for the presence of predictors of asthenopia. RESULTS: Social support, group conflict, self esteem, work satisfaction, and underuse of skills were found to be predictors of visual complaints; social support played a part also as a moderating factor in the stress and strain model; this model accounted for 30% of the variance. Subjective environmental factors, although in some cases significantly correlated with asthenopia, were not found to be strong predictors of the symptoms. CONCLUSIONS: Some part of the complaints about visual health reported by VDT workers are likely indirect expressions of psychological discomfort related to working conditions.

[Ophthalmologic evaluation of VDT/PC operators: approach to the diagnosis with neural networks]. / Valutazione oculistica in operatori addetti a VDT/PC: un approccio alla diagnosi mediante rete neurale.

The present study was performed to build a neural network as a diagnostic tool to aid ophthalmologic examination of VDT/PC operators. The network was built on anamnesic and ophthalmologic data (visual acuity and mesopic vision, contrast sensitivity) from 278 VDT/pC operators and is able to predict 88% of total cases who need specialist attention, when ocular pathologies are also present, and 91% when only refraction defects are present. The tests chosen for this study are not useful to build a very sensitive discriminant model. This study confirm the absence for useful ophthalmologic tests in screening of VDT/PC operators, particularly when ocular pathologies are present without refractive errors. For their capacity to translate on a clinical-pratic plane knowledge obtained through studies conducted on large populations, the neural networks seem to be a good diagnostic tool.

[Application of neural networks in occupational medicine]. / Applicazioni delle reti neurali in medicina del lavoro.

The medical literature offers today many contributions in which neural networks have been used. The introduction of these tools as diagnostic aid appears very interesting also into various sectors of research in the occupational field. The author proceeds to a schematic description of the functioning of a neural network, describing an applied example. It is therefore estimated the feasible advantages which result from the use in the research of neural networks. Finally a possible fields of use of the neural networks in occupational medicine is highlighted, from the detection of lung nodules in digital chest radiographs to the detection of peripheral vascular disease from upper limb pulse waveforms, from the low back disorders due to workplace design to the diagnosis of occupational asthma.

[Specialist assessments and Law Decree 626/94 on operators employed at VDT/PCs]. / Accertamenti specialistici e D.Lvo 626/94 in operatori addetti a VDT/PC.

Within the context of the health protection of employees working with monitors and personal computers, we evaluated the capacity of certain ophthalmologic tests, which can be used by corporate medical doctors even if they have not received specific ophthalmologic training, to identify ophthalmologic-visual conditions which should be referred to a specialist. 278 employees working with computers underwent a complete ophthalmologic test including contrast sensitivity, the red-green test, the dynamic acuity and the mesopic test. Two groups (with and without ocular pathologies) whose characteristics indicated the need of a specialist examination were then chosen, and the correlation and predictive capacities of the single tests or their combination was then evaluated with regard to the two groups. The model developed through a discriminating analysis vaunts a predictive sensibility above 95%, thus allowing to identify almost all persons in the sample group who should be referred to a specialist when used to identify those afflicted solely by refraction alterations, while it drops to 66% with a specific figure of 89% when non-refractive ocular pathologies coexist. The figures indicate that certain evaluation tests can be used to efficiently screen visual functionality by the corporate medical doctor. The authors offer suggestions on the need for a correct and carefully considered strategy to adopt for the screening of visual function.

Pulmonary function in Sardinian fire fighters.

Our study examined the respiratory function of 92 firemen whose main activity is fire fighting in forests and open country. Such fire fighting activities are to be considered a risk to the respiratory tract, taking into account studies already in the literature that have evaluated the nature and quantity of inhalable toxins present in activities of this kind. The control group was composed of 51 Carabinieri (policemen), who were asked to fill in a questionnaire about their work activities. Forced expiratory volume and flow, total lung capacity, respiratory volume, and the permeability of the alveolar-capillary barrier were measured. Firemen and Carabinieri (policemen) showed FVC rates higher than the European Community for Coal and Steel standards. The firemen showed a significant reduction in forced expiratory volume in 1 second (FEV1)[3.90 (0.50) vs. 4.04 (0.44); p < 0.05] and forced expiratory flow at 75% of forced vital capacity (FVC) (FEF75) [8.37 (4.11) vs. 8.38 (1.67) p < 0.05] and more markedly in the FEV 1/FVC relationship [80.07 (5.89) vs. 83.89 (1.67) p < 0.001] and in FEF50 [4.73 (1.34) vs. 5.54 (1.44) p < 0.01] and FEF25[1.58 (.47) vs. 1.99 (.69) p < 0.001]. There were no marked differences in air-blood exchanges. No correlation was found between respiratory function data and years of service or the number of fires extinguished during work experience.