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Biomedical subjects

M Imbriani

Publications and source records attributed to M Imbriani.

At least 55 records · Page 3Linked to original sources
PubMed1990

1,2-Dichloropropane hepatotoxicity in rats after inhalation exposure.

The hepatic effects of 1,2-dichloropropane (DCP) were investigated in male Wistar rats exposed to 15, 50, 100, 250, 450, 1000, 1300, 1800 or 4900 mg DCP m-3. At the end of a 4-h period of exposure, average blood DCP levels were 0.025 and 5.38 micrograms ml-1 in animals treated with 15 and 1300 mg m-3, respectively. Blood DCP concentrations were correlated with the air DCP concentrations in the inhalation chamber. At DCP concentrations of 100 mg m-3 or higher, the liver non-protein thiol (NPT) content was significantly reduced. Assays performed 20 h after 4-h DCP exposure showed that exposure to 100-1000 mg DCP m-3 had no effect on hepatic NPT levels. The NPT content increased only in the liver of rats exposed to higher (1300-4900 mg m-3) DCP concentrations. Treatment with DCP did not cause hepatic lipid peroxidation and did not modify total protein content. The observed changes in liver cell thiol homeostasis are likely to reflect the action of reactive intermediates formed during DCP metabolism. These changes can occur in rats following exposure to considerably low levels of DCP vapour.

Administration, Inhalation↗
PubMed1989

[Occupational asthma].

Bronchial asthma has been defined as a state of airway obstruction of variable degree correlated casually with exposure to volatile dusts, gases, vapours or fumes in the working environment. In this review we considered the causes of occupational asthma, the diagnosis, the pattern of asthmatic reactions and their mechanism, the predisposing factors, the epidemiology, the prognosis and finally the cure and prevention (review article, 165 references).

Asthma↗
PubMed1989

Methyl ethyl ketone (MEK) in urine as biological index of exposure.

Fifteen human volunteers were exposed to methyl ethyl ketone (MEK) vapor at 11.9-621.8 mg/m3 for a period of 2 to 4 hours at rest (ten cases) and during light physical exercise (five cases). Subsequently 78 workers occupationally exposed to MEK in a manufacture of leather suitcases (median value: 75.5 mg/m3; geometrical standard deviation: 3.12 mg/m3; range: 6-790) were studied. The analyses were performed by means of a Gas Chromatograph (GC) Hewlett-Packard 5880 A connected with a Mass Selective Detector (MSD). The relative uptake (R) of MEK was about 0.54 (standard deviation: 0.05) and it keeps practically constant either at rest or during light effort (V < 30 L/min). A linear relationship existed in the experimentally exposed subjects between urinary concentration (Cu) and amount of MEK absorbed (U) (Cu = 3.05 x U-162.1; r = 0.95; n = 15) (Cu = micrograms/L; U = mg). Both in the experimentally exposed subjects and in the occupationally exposed workers, the urinary concentration of MEK shoved a linear relationship to the corresponding environmental time-weighted average concentration (CI). The correlation coefficients (r) were 0.93 in occupationally exposed subjects (regression equation: Cu = 0.004 x CI + 0.118; n = 78); Cu = mg/L; CI = mg/m3) and more than 0.93 in experimentally exposed groups. The findings indicate that the urinary concentration of MEK can be used as an appropriate biological exposure indicator.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

1,1,1-Trichloroethane (methyl chloroform) in urine as biological index of exposure.

Fifteen human volunteers were exposed to 1,1,1-trichloroethane (methyl chloroform) vapor at 72-495 mg/m3 for a period of 2 to 4 hours at rest (ten cases) and during light physical exercise (five cases). Subsequently 60 workers occupationally exposed to 1,1,1-trichloroethane in a refrigerator manufacturing plant were studied (median value: 178 mg/m3; geometrical standard deviation: 2.19 mg/m3). As expected, the relative uptake (R) of 1,1,1-trichloroethane decreased in the course of exposure at rest (R = 0.44 after 20 minutes of exposure; R = 0.26 after 240 minutes of exposure). Both in the experimentally exposed subjects and in the occupationally exposed workers, the urinary concentration of 1,1,1-trichloroethane showed a linear relationship to the corresponding environmental time-weighted average concentration. The correlation coefficients (r) were 0.95 in occupationally exposed subjects and more than 0.90 in experimentally exposed groups. A linear equation also existed between urinary concentration and amount of 1,1,1-trichloroethane absorbed (r = 0.88). The findings indicate that the urinary concentration of 1,1,1-trichloroethane can be used as an appropriate biological exposure indicator. In occupationally exposed subjects performing moderate work, the urinary 1,1,1-trichloroethane concentration corresponding to the time-weighted average of the threshold limit value was found to be 860 micrograms/L and its 95% lower confidence limit (biological threshold) 805 micrograms/L.

Adult↗
PubMed1988

Evaluation of exposure to isoflurane (Forane): environmental and biological measurements in operating room personnel.

The concentration of isoflurane (Forane) in the ambient atmosphere was determined in 11 operating theaters of 5 hospitals in Italy. The concentration of isoflurane in the ambient air exceeds the recommended time-weighted average exposure levels (median value: 113 mumol/m3). Isoflurane was detected in the urine of 45 exposed subjects (anesthetists, surgeons, and nurses). A significant correlation was found between the isoflurane concentration in urine produced during the shift (Cu' nmol/l) and isoflurane environmental concentration (Cl' mumol/m3) (Cu = 0.243 X Cl + 3.712) (r = .90). The results show that the urinary isoflurane concentration can be used as an appropriate biological exposure index. The authors suggest a biological exposure index of 18 nmol/l (3.4 micrograms/l). This is the biological value obtained after 4 h of an average environmental exposure to 81 mumol/m3 (2 ppm).

Adult↗
PubMed1988

Urinary concentration, environmental concentration, and respiratory uptake of some solvents: effect of the work load.

The physical demands of the workplace differ depending on specific jobs. This implies that workers exposed to the same environmental level of an airborne contaminant can absorb different amounts of it depending on their pulmonary ventilation. Starting from the relationship between the uptake (U) and the urinary concentration of six solvents (Cu) (acetone, styrene, toluene, xylenes, methylchloroform, tetrachloroethylene) and from the equation expressing their lung uptake (U = K.V.CI.R.T) the expected values of a biological index after a given time of exposure can be derived. Such values are a function not only of the environmental level of exposure (CI) but also of the pulmonary ventilation (V - dependent solvent) and of the retention index (R) (V - R dependent solvent).

Air Pollutants, Occupational↗
PubMed1988

[Vitiligo appearing after contact with mud containing solvents: an occupational cause?].

The authors describe one case of Vitiligo in a worker employed in a firm for the exploitation of underground energetic products. The disease occurred after contact with the mud used for the drilling containing aromatic, aliphatic and chlorinated hydrocarbons. The possible occupational cause of the disease, as more solvents in the mud have the structure of aromatic hydrocarbons is discussed.

Humans↗
PubMed1987

Methemoglobin and carboxyhemoglobin levels in smokers and non smokers.

The authors examined the blood of 856 subjects (377 smokers and 479 non smokers) in order to evaluate the levels of Methemoglobin (MetHb) in relationship to tobacco smoke. The Methemoglobin, Carboxyhemoglobin, Percent Oxyhemoglobin and Total Hemoglobin were measured using an automated spectrometer (IL 282 CO - Oximeter). The authors found that the levels of MetHb in the smokers exceed that in the non smokers: in fact the level of MetHb in the smokers (% MetHb = 0.63) was significantly greater than in the non smokers (% MetHb = 0.56), unlike what was reported in literature. The levels of Carboxyhemoglobin in the blood has been shown to be a useful marker of tobacco smoke absorption: a close relationship exists between COHb and cigarette smoking.

Adolescent↗
PubMed1987

[Use of gas chromatography with flame ionization (GC-FID) in the measurement of solvents in the urine].

The urinary concentration of some solvents (acetone, cyclohexane, 1,2 dichloropropane, n-hexane, methyl ethyl ketone, perchloroethylene, styrene, toluene, 1,1,1, trichloroethane) was measured by means of a gas chromatography Hewlett-Packard 5890 supplied with a flame ionization detector (GC-FID, DANI HS 3950). The coefficient of variation of the method was lower than 5%. The sensitivity of the GC-FID was very similar to what of mass spectrometer detector (GC-MSD, HP 5970 A).

Acetone↗
PubMed1987

The urinary concentration of solvents as a biological indicator of exposure: proposal for the biological equivalent exposure limit for nine solvents.

Organic solvents are generally volatile substances that are absorbed mainly through the lungs; they are eliminated chiefly through the lungs and kidneys. In urine they are present as metabolites and, in very little part, as parent compound. The urinary concentration of solvent (Cu) can be used for the biological monitoring of exposed subjects to evaluate their exposure and correlate with the Threshold Limit Value (TLV) during the working day. The authors report some results obtained with workers occupationally exposed to solvents. The results concern the correlation between urinary concentration (Cu, micrograms/L) vs. average environmental concentration (Ci, mg/m3) measured in the breathing zone. For each solvent studied (acetone, 2-cyclohexane, 1,2-dichloropropane, n-hexane, methyl ethyl ketone, perchloroethylene, styrene, toluene, 1,1,1-trichloroethane) the authors propose a Biological Equivalent Exposure Limit (BEEL) corresponding to the environmental TLV.

Air Pollutants, Occupational↗
PubMed1986

Urinary elimination of acetone in experimental and occupational exposure.

Fifteen volunteers were exposed to an acetone vapor concentration of 964-8, 610 mumol/m3 (56-500 mg/m3) for 2-4 h in an exposure chamber. Ten subjects were at rest during the exposure, and five were exposed at alternate rest and light physical exercise. Subsequently 104 workers occupationally exposed to acetone were studied. The relative uptake averaged about 53%, and the ratio of the alveolar concentration to the environmental concentration averaged about 0.28. Both for the experimentally exposed subjects and the occupationally exposed workers the urinary acetone concentration showed a linear relationship to the corresponding environmental time-weighted average concentration. A linear equation also existed between urinary concentrations and the amounts of acetone absorbed. The findings enable a consideration of the urinary concentration of the unaltered acetone as an appropriate exposure indicator and the proposal of a "biological equivalent threshold" to be used in the field of biological monitoring.

Acetone↗
PubMed1985

Urinary elimination of styrene in experimental and occupational exposure.

Twenty human volunteers were exposed to styrene vapor at 273-1 654 mumol/m3 (28.4-172.3 mg/m3) for a period of 1 to 3 h at rest (15 cases) and during light physical exercise (5 cases). Subsequently 51 workers occupationally exposed to styrene were studied during a workweek (median value 1 138 mumol/m3, geometric standard deviation 2.23). As expected, the relative uptake averaged about 65%, and the ratio of the alveolar concentration to the time-weighted average of the environmental concentration averaged about 0.15. Both in the experimentally exposed subjects and in the occupationally exposed workers the urinary styrene concentration showed a linear relationship to the corresponding environmental time-weighted average concentration. The correlation coefficients of the regression lines ranged between 0.88 (occupationally exposed group) and more than 0.93 (experimentally exposed groups). The regression coefficients were closely linked to the amount of styrene taken up and to the exposure times. The findings show that the urinary styrene concentration can be used as an appropriate biological exposure indicator whose meaning differs from that of other suggested indices. As an example, in occupationally exposed subjects performing moderate work the urinary styrene concentration corresponding to the time-weighted average of the threshold limit value is 815 nmol/l, and the 95% lower confidence limit (biological threshold) is 740 nmol/l.

Adult↗
PubMed1985

Urine/air partition coefficients for some industrially important substances.

The urine/air and blood/urine partition coefficients (lambda) of 43 commonly employed organic solvents (Aliphatic, Cyclic, Aromatic and Halogenated Hydrocarbons, Ketones, Alcohols and Esters) are reported. The analyses were performed by the multiple equilibration method (constant pressure method) using a Hewlett-Packard 5880 gas chromatograph. The lambda values proposed can be employed in the field of biological monitoring of subjects occupationally exposed to solvents vapors.

Air Pollutants, Occupational↗
PubMed1985

Respiratory measurements of occupational exposure to industrial solvents.

The authors report the parameters which rule the absorption and elimination of polluting solvent vapours in exposed subjects (Ventilation, Pulmonary Capillary Flow, Solubility Coefficients, Environmental Concentrations, Exposure Times). These parameters are included in the equations showing the absorption and elimination indexes and lung clearances. Some methods to measure the Solubility Coefficients of inert gases in biological media and the values referring to 51 industrial solvents, commonly employed or important from the toxicological point of view, are described. Finally the Authors report some experimental results obtained in exposure chamber on volunteers, and in occupationally exposed subjects directly in workplaces. The results are discussed stressing their practical usefulness in the field of biological monitoring, industrial hygiene and in preventive medicine.

Absorption↗
PubMed1984

[Changes induced by dimethylformamide on platelet function and coagulation activity].

The effect of Dimethylformamide on platelet function and on clotting system has been studied on eight workers exposed to the product, widely used in industry as a solvent of acrylic resins. A significant reduction of the number of the platelets and a drawing out of PTT and PT has been noticed. Such informations has been explained as chronical peripheral use or as modification of phospholipid components induced by DMF instead of synthesis defect, as no significant variation of the fibrinogen and of AT III values, proteins synthetized by liver, has been observed. The platelet aggregation has pointed out, in vivo, a reduction of ADP aggregation in the exposed subjects; in vitro, increasing quantities have determined an increasing reduction of the primary ADP and adrenaline aggregation.

Adult↗
PubMed1984

[Stability of esters in the blood in vitro].

The aim of this paper was to evaluate the lambda values of this group of solvents experimentally, by means of an analytical method which has already been used for other solvents. During our experiments we found that most acetates we tested (n-butyl-acetate; sec.butyl-acetate; ter-butyl-acetate; ethyl-acetate; amyl-acetate; methyl-acetate; n-propyl-acetate) were particularly unstable and hydrolyzed rapidly in alcohol and in the corresponding acid. The "in vitro" behaviour of these substances allow to draw the following conclusions: 1) For the acetates it is not possible to measure the values since the involved substances are chemically unstable in blood. 2) As it was shown by the half-life times of the "in vitro" acetates, the alcohols and the corresponding acids, are released rapidly in blood. 3) The biological monitoring of the acetates in expired air is not very significant; perhaps it is better to measure the corresponding alcohol in expired air. 4) In some cases the TLV of the alcohols is much lower than for the corresponding acetates; this finding and the rapid biotransformation we observed make us think that the TLV's proposed for some acetates are too high.

Acetates↗
PubMed1984

[N-hexane and toluene in the urine of occupationally exposed subjects. Measurement and significance of its presence].

N-hexane and toluene in the urine of occupationally exposed subjects. Measurement and significance of their presence. The determination of n-hexane and toluene in urine was performed in 23 subjects who were occupationally exposed to n-hexane and in 8 subjects exposed to toluene, by means of the head space technique. A Hewlett-Packard 5880 A gas chromatograph supplied with Hewlett-Packard 5970 A Mass Selective Detector was employed. The Authors found significant correlations between urine concentration of the substance and environmental concentration (for n-hexane r = 0,866; for toluene r = 0,770.

Adult↗