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Biomedical subjects

M Imbriani

Publications and source records attributed to M Imbriani.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

[Exposure to acetone: experimental study of absorption and pulmonary elimination in normal subjects].

Alveolar (CA) and mixed expired air (CE) acetone concentrations were measured in 15 healthy volunteer subjects, exposed to acetone (CI) in an exposure chamber (exposure range: 48-565 mg/m3) both at rest and during exercise (50 W). The Relative Uptake (R = 1-CE/CI) was 0.54 at rest (120' and 240') and 0.55 during exercise (120', 50 W). Ca:CI ratio was 0.24 at rest. CE:CI and CA:CI ratio was constant throughout the exposure time, both at rest and during exercise.

Acetone↗
PubMedDate not supplied

[Physical workload demands: the combined use of 2 evaluation programs].

A computerized methodology is presented for the "on-site" evaluation of work-related physical activities in industrial plant workers. Subjects were videotaped during the activities while heart rate and subjective perception of effort were monitored. The videorecordings were then analyzed with two appropriate software, in order to identify activities at high risk for musculoskeletal injuries ("Vision 3000" program, Promatek Ltd., Montreal) and to evaluate energy expenditure ("Energy" program, University of Michigan). Validation of the energy expenditure indirect analysis system was done by monitoring oxygen consumption (VO2) with a portable telemetric oxygen uptake analyzer ("K2", Cosmed, Rome). No statistically significant differences were found between direct measurements of VO2 and laboratory-derived estimates of energy consumption. The utilization of these two software provides a fast and reliable profile of job requirements and associated risks of musculoskeletal injury.

Biomechanical Phenomena↗
PubMedDate not supplied

The pulmonary capillary blood flow (Qc) at rest and work measured simultaneously by 3 inert substances.

We have considered the opportunity of using some inert vapours (2-3 Dimethylbutane, 2 Methylpentane, n-Hexane) to measure the pulmonary capillary blood flow (Qc). The measurements were performed by means of a gas chromatograph connected with a mass spectrometer. The alpha values (Bunsen absorption coefficients) measured by a constant pressure method (multiple equilibration methods) were reported. Qc was measured in 14 healthy subjects at rest and in 5 subjects during exercise (25 and 50 watt by means of a cyclo ergometer, steady state test) (rebreathing method). The method used allow multiple measurements of Qc during the same exercise test.

Adult↗
PubMedDate not supplied

[Determination of low levels of urinary trans,trans-muconic acid].

A method is described which allows determination of urinary t,t-muconic acid (MA) by means of HPLC with UV detection even at micrograms/l concentrations. The clean-up procedure of samples involves the use of strong anionic-exchange cartridges (SAX) for solid phase extraction (SPE). In order to improve the reproducibility of the retention time of MA (CV < 1%) and to obtain an adequate separation of MA from interferents, a high performance reverse-phase column (250 x 4.6 [I.D.] mm, 3 microns) is used and a careful control of the temperature (25 degrees C) is made. Also, a column-switching technique is applied to the chromatographic system in order to eliminate the highly retained peaks from the analytical column. The isocratic run is performed at a constant flow rate of 0.7 ml/min; the mobile phase consists of water: methanol: acetic acid (93.5:5.5: 1, v/v) and the UV detector is set at 259 nm. Under these conditions, MA elutes at 21.5 min and a single analysis takes 25 min; the detection limit (at a signal-to-noise ratio of 3) is 3 micrograms/l in urine, when a 200 microliters aliquot of the extract is injected in the analytical apparatus. The recovery of the clean-up procedure is > 90%; both the intra-assay and the inter-assay coefficients of variation are < 4%. The method has been applied to smokers and nonsmokers, subjects occupationally unexposed to benzene; the results showed a statistically significant difference between the two groups. Also, a close correlation was found between urinary excretion of MA measured with this method and environmental concentration of benzene in a population of workers occupationally exposed to low levels of this solvent.

Air Pollutants, Occupational↗
PubMedDate not supplied

[The measurement of a benzene metabolite, urinary S-phenylmercapturic acid (S-PMA), in man by HPLC].

Benzene is a widely used solvent, currently present in the industrial environment at concentrations in the order of ppm. A valid method of biological monitoring that is easy to perform is needed for assessing occupational exposures. Benzene is metabolized in the body by microsomal cytochrome P-450 mono-oxygenase system into benzene epoxide. Benzene epoxide is metabolized along three different pathways which end in the excretion of trans, trans muconic acid, S-phenyl-mercapturic (S-PMA) and different phenols. A new method has been developed to evaluate urinary S-PMA of subjects exposed to benzene. Human urine is acidified with HCl to PH 1 and passed through a Sep-Pak C18 cartridge. The cartridges are washed with diluted HCl and a mixture of water/methanol/acetic acid and then eluted with acidified chloroform. The eluate is dried and reconstituted with a buffer phosphate, then passed through an anionic exchange cartridge (SAX) which is washed with diluted buffer and diluted HCl. S-PMA is recovered by eluting with concentrated buffer and is transformed into S-phenyl-cysteine. Finally, S-phenyl-cysteine is detected by HPLC connected with a fluorescence detector (wavelengths: excitation 330 nm, emission 440 nm) after derivatization with o-phthalaldehyde (OPA) and 2-mercapto-ethanol (MCE). The detection limit of the method is about 0.5 micrograms/l, the recovery of S-PMA is 90.0% and the variation coefficient is 3.8%. The method was checked on urine samples of 8 male non-smokers and 10 smokers: median values of 1.3 and 9.2 micrograms/g creatinine respectively of S-PMA were obtained. A further analysis on urine samples of 66 occupationally exposed workers (smokers and non-smokers) revealed a median value of S-PMA of 46.6 micrograms/g creatinine, compared with a median environmental benzene exposure of 1.99 mg/m3. These results suggest that S-PMA can be regarded in the future as a useful indicator for monitoring individual and collective low-level benzene exposure.

Acetylcysteine↗
PubMedDate not supplied

[Retrospective study of the morbidity in a group occupationally exposed to chlorotriazine herbicides: preliminary results].

Two different groups of workers, involved in production or formulation of chlorotriazine herbicides during the last 10 years, have been retrospectively studied for occurrence of diseases related to the exposure to Atrazine, Simazine, Propazine, and Terbuthylazine. A control group has been selected between clerical workers of the same plants. Subjects exposed to the different compounds have been studied for inhalator and dermal exposure by active sampling, skin pads, and hand washings; samples have been further processed and specifically analysed. Urines have been studied for the presence and concentrations of mono and bidealkylated triazine metabolites. Exposure data have been collected during the last five years and extrapolations have performed for exposures in the preceding years. Clinical finding and laboratory data for all workers have been obtained from medical surveillance records. Data available for the last 10 years have been evaluated to highlight possible differences between the investigated groups.

Adult↗
PubMedDate not supplied

[Environmental and biological monitoring of occupational exposure to perchloroethylene in dry cleaning shops].

Occupational exposure to perchloroethylene (PCE) was studied in a total of 106 workers in 78 dry cleaning shops in the province of Pavia, Northern, Italy. Environmental monitoring was performed by personal passive sampling. The median time weighted average (TWA) level of PCE was 57 mg/m3, i.e., about 30% of the current Threshold Limit Value (TLV) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH). However, in 12 workers exposure exceeded this limit. Biological monitoring was performed via measurement of urinary trichloroacetic acid (TCA), i.e. the exposure index currently used in Italy, and urinary excretion of unmodified perchloroethylene (PCE-U) in samples collected at the end of the half-shift. Median levels of TCA and PCE were 1.03 mg/l and 17.7 micrograms/l respectively. The correlation coefficient between environmental TWA concentrations of perchloroethylene and PCE-U was 0.755 (0.809 after logarithmic transformation), compared to 0.660 for TCA values. The subjects were then classified as "low exposed" and "heavily exposed" according to whether personal exposure was lower or higher than 57 mg/m3, the median TWA value of the whole group. PCE-U levels were significantly correlated to exposure in both subgroups whereas TCA was correlated only in the "heavily exposed subjects", but not in those with lower exposure. The results of the study show that in the majority of dry cleaning shops exposure to PCE was well below the current occupational limits. Nevertheless surveillance of dry cleaners is recommended as nearly 10% of the workers exceeded the environmental and biological limits. Urinary excretion of unmodified PCE appears to be a very reliable indicator for biological monitoring of PCE exposure in dry cleaning and is also significantly correlated to exposure at low levels. The estimated biological equivalent exposure level (BEEL) for PCE-U, corresponding to the current TLV-TWA proposed by the ACGIH, is 55 micrograms/l. Urinary TCA seems to be less suitable for assessment of individual exposure to perchloroethylene in dry cleaners as it is poorly representative of exposure to low levels of the solvent, which is a very common occurrence in this occupational group nowadays.

Adult↗
PubMedDate not supplied

[Aerobic fitness in police officers].

According to act n. 626, individual assessment of fitness and absence of contraindications for carrying on a job is fundamental. We considered a group of 44 Urban Police officers (36 males, 8 females), age 39.7 +/- 9.1, whose principal job requirement is a good energetic and motor availability, for a fitness evaluation through a submaximal treadmill test, with subsequent steps of 6 minutes. During the test, physiological variables (VO2, VE, QR through a metabograph, Hr trough an Ec-monitor and Pa through a manual sphygmomanometer) and subjective evaluations of fatigue and dyspnea were monitored. Studying the individual variables trend it was possible to identify the critical metabolic level that was easily tolerated by each individual. This level, an average of 6.8 MET corresponding to a heavy activity, is an endurance predictor and can be utilized in subsequent controls.

Adult↗
PubMedDate not supplied

[Indoor pollution and biological monitoring of volatile organic compounds (VOC)].

Indoor air is a complex mixture of chemicals and airborne particles. Volatile Organic Compounds (VOC), a broad class of chemicals including diverse compounds such as Aldehydes, Terpenes, Aromatic and Aliphatic Hydrocarbons and Halogenated Volatile Organics, are an important category of indoor air pollutants. The evaluation of exposure to low doses of Chloroform and Benzene through the measurement of Chloroform and Benzene in urine was performed. Results show that biological monitoring may be helpful in indoor environmental studies in non occupational situations.

Air Pollution, Indoor↗
PubMedDate not supplied

Partition coefficients of methyl tert-butyl ether (MTBE).

The knowledge of the partition coefficients between the air and arterial blood and between the blood and the different physiological compartments of the body are essential to the mathematical modelling of the respiratory uptake and elimination of toxic vapours. Partition coefficients of methyl tertbutyl ether (MTBE) in saline, olive oil, urine and human blood, and various rat tissues were calculated after gas-chromatographic quantification of MTBE in the air phase. The blood/air, urine/air saline/air, fat/air and oil/air partition coefficients (lambda) are respectively: 20.0, 15.6, 15.3, 142.0 and 138.

Adipose Tissue↗
PubMedDate not supplied

[Diffusion sampling of benzene present in the urine].

Benzene is a widely diffuse solvent; in the industrial environment benzene is currently present at concentrations of ppm. A valid method of biological monitoring that is easy to perform is need for assessing occupational and non-occupational exposures. A new method has been developed to evaluate low concentrations of benzene in urine samples by means of a diffusion sampling. The solvent is absorbed from the urine surface and concentrated on an absorbent substrate (Tenax) that is placed inside the vial. The solvent is thermically desorbed from Tenax and injected into a column (Thermal Tube Desorber-Supelco; 250 degrees C thermal flash; borosilicate capillary glass-column SPB-I 60 m length, 0.75 mm I.D., 1 micron film thickness; GC Dani 8580-FID). The method, which had not been previously employed for the determination of volatile organic substances in biological fluids, has a linear range which extends up to 40 micrograms/l, and gives results in excellent agreement with the conventional Head Space method, except in the low concentration region: the new method permits the quantitative determination of benzene quantities smaller than the detection limit of Head Space method connected with mass spectrometer (approximately 1 microgram/l). The detection limit was not exactly determined, but is estimated to be of 100 ng/l with 25 ml of urine sample.

Benzene↗
PubMedDate not supplied

[Processes of speech production: Application in a group of subjects chronically exposed to organic solvents (II)].

The aim of this study was to evaluate the effects of chronic exposition to neurotoxic solvents in a group of laundry operators by means of Vocal Reaction Times (VRTs) measurements. A group of normal subjects, matched for age and educational level, constituted the controls. Vocal Reaction Times were measured by a device that presented to each subject a sequence of words on a computer screen, acquired the acoustic signal and measured VRTs and durations. During the test a random sequence of words was presented to the subjects; the protocol consisted of two immediate reading task and two delayed reading tasks. The test was performed using concrete and meaningless words. Statistical analysis showed that reaction times measured on the acoustic signals were longer for the exposed group than for the controls. The differences between durations were significant for the delayed reading tasks using concrete words and for all tasks using meaningless words. These findings suggest that this technique may be considered a useful tool for the assessment of the preclinical alterations of CNS in the monitoring of individuals chronically exposed to neurotoxic solvents.

Adult↗