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Biomedical subjects

A Colombi

Publications and source records attributed to A Colombi.

At least 37 records · Page 2Linked to original sources
PubMed1977

Metabolism of quaternary carbon compounds: 2,2-dimethylheptane and tertbutylbenzene.

Two Achromobacter strains capable of utilizing 2,2-dimethylheptane or tertbutylbenzene as the sole carbon and energy source were isolated from waste-water. Pivalic acid was found in the cultures of Achromobacter A1 containing 2,2-dimethylheptane. From cultures of Achromobacter A2 in the presence of tertbutylbenzene, a diol was isolated and identified as 2,3-dihydro-2,3-dihydroxytertbutylbenzene. Evidence for meta cleavage of the aromatic ring and for accumulation of pivalic acid in the cultures was also obtained. A metabolic pathway for tertbutylbenzene is suggested.

Alcaligenes↗
PubMed1976

[Peritoneal dialysis, ultrafiltration and hyperosmolarity].

Observation of a patient who developed serious hypernatremia during peritoneal dialysis with a dialysis fluid containing 135 mval Na+/1 prompted investigation of net water, sodium, potassium and chloride transport during 45 peritoneal fluid exchanges with standard dialysis solutions containing 1.5 and 4.5 g% glucose. With both solutions and an equilibration time of 0 min, net ultrafiltration was observed (89 ml and 230 ml per exchange respectively). In both groups the calculated sodium concentration of the ultrafiltrate was considerably lower than plasma sodium concentrations (27.0 mval/1 and 36.9 mval/1 respectively, resulting in a new sieving coefficient of 0.20 and 0.27 respectively. Therefore, the free water deficit resulting from peritoneal ultrafiltration is directly responsible for the hypernatremia observed during peritoneal dislysis. While the potassium and chloride transport observed in these studies can be explained by diffusion processes along a given concentration gradient, sodium transport and sodium concentrations raise the question of more complex mechanisms. The data are discussed with reference to the relative significance of diffusion processes versus bulk flow and solvent drag.

Biological Transport↗
PubMed1976

An electrophysiological investigation of skeletal muscles in polymyositis.

An electrophysiological study has been made of the extensor digitorum brevis, thenar and hypothenar muscles in 25 patients with chronic and acute polymyositis. It was found a reduction of the number of functioning motor units in some patients with chronic polymyositis and only in one of those affected by acute polymyositis and only in one of those affected by acute polymyositis. The sizes of the surviving units suggested that the results could be explained in terms of a primary muscle involvement mainly in acute polymyositis, while in chronic polymyositis a combination of primary and neurogenic involvement of muscle fibers might take place.

Acute Disease↗
PubMed1975

Hypotensive effect of oxprenolol in mild to moderate hypertension: a multicentre controlled study.

In a multicentre, double-blind, between-patient study the hypotensive effect of oxprenolol was investigated in 329 patients with mild to moderate hypertension. A factorial experimental design with three factors was chosen: oxprenolol--none or daily doses of 20, 40, 60 and 80 mg; dihydralazine and hydrochlorothiazide, respectively, none or 30 mg daily. Each treatment was given for 4 weeks after an adequate period of withdrawal from any other possible hypotensive therapy and one week of placebo wash-out. Irresponsive of the association with dihydralazine and/or hydrochlorothiazide, oxprenolol had a hypotensive effect linearly related to dose for standing systolic (P less than 0.05) and diastolic (P less than 0.01) pressure, and for lying diastolic (P less than 0.05) pressure. The additional of dihydralazine enhanced the time-course of the hypotensive effect of oxprenolol, particularly the 80 mg dose level. In general, the combination of oxprenolol with dihydralazine and hydrochlorothiazide caused larger reductions in blood pressure, particularly with oxprenolol 80 mg. In the latter group, the eventual falls in blood pressure were 30.5 and 14.4 mmHg for lying systolic and diastolic, respectively; and 32.1 and 20.0 mmHg for the standing systolic and diastolic pressures. The drug was well tolerated; major side effects (heart failure and bronchospasm) occurred in three patients.

Clinical Trials as Topic↗
PubMed1975

[Electrophysiology in neuropathy caused by vincristine].

Ten patients treated with vincristine were submitted for electrophysiological examination. It was investigated the number of motor units within the thenar muscle following a technique described previously (Sica et al. - 1974); motor and sensitive conduction velocities as well as motor distal latencies in the median nerve were studied following conventional techniques. The behaviour of the evoked muscle potential with repetitive supramaximal stimulation over the median nerve was also investigated. The findings were compared with control groups. The estimated number of motor units was disminished in eight of ten patients and the average number was significantly different from the control group (control 318 +/- 71 UM; patients 174 +/- 84 UM; P less than 0.001). The potential amplitudes in most of the surviving units were reduced, others remaining within the normal range. This makes apparent that the peripherical nervous system fails to compensate adequately and, furthermore, a loss of individual muscle fibres occurs within some individual units. The conduction velocities of the fastest conducting motor nerve fibres were reduced and motor distal latencies prolongued (Table 1). Maximal impulse conduction velocities were measured in sensory fibres. In 5 of 7 subjets investigated the values laied just beyond the lower limit of the normal range. The amplitude of the sensory orthodromic evoked potential in the median nerve at the wrist was disminished almost in the whole group. The decremental muscle response to repetitive nerve stimulation, can be interpreted as the result of the damage at the neural apparatus at the motor end plate; it was observed in 57% of the patients. In summary, evidences have been registered showing that the nervous supply to the muscle is affected in patients treated with vincristine; the motor unit behaviour under this conditions is discussed.

Adult↗
PubMedDate not supplied

[Measurements and environmental and biological monitoring of occupational exposure to inhalation anesthetics].

This paper reports the data of nitrous oxide (N2O) environmental pollution in 269 operating rooms of 47 hospitals in Italy in 1989-91. In 40% of the operating rooms the N2O concentrations are lower than 50 ppm, limit value proposed by Health Council for new operating rooms. In 65.4% of the operating room studied, N2O mean environmental concentrations are lower than 100 ppm, value proposed by the above-mentioned Health Council as limit value for the already existing operating rooms. Concerning the biological monitoring, the authors report several N2O data in urine (2193), whose levels confirm the data obtained with environmental monitoring. The authors believe that they presently have reliable methods to perform biological and environmental monitoring: the two techniques are complementary in the assessment of the exposure. The method of measuring N2O concentrations as exposure index, both for the environmental and biological monitoring, is considered very useful to simplify the performance of the analyses. In order to assess exposure more precisely, it is however necessary also to determine the environmental and/or biological measure of the other different anaesthetics used.

Air Pollutants, Occupational↗
PubMedDate not supplied

[Health risks for waste disposal industry workers].

Waste disposal currently constitutes a major public health problem in Italy and other industrialized countries. In view of the increasing volume of waste accumulated and disposed of without control, there is now an ever pressing need for regulated disposal that involves minimum risk for the environment and the community. Hence a new industrial sector has emerged that is highly specialized and varied, on account of the wide field of activity and technology, from collection and storage of refuse, processing and definitive disposal, to reclamation and improvement of illegal dumps. The industrial waste sector has not been fully developed and it is currently believed that most disposal is performed without sanitary control. Little attention has been given to the environmental impact of these operations and similarly little is known of the possible health effects for the operators. Acquisition of toxicological and health data is therefore essential to establish correct and appropriate regulations for the development of this industrial sector. An objective risk evaluation will require filling in many information gaps, which are partly the results of a natural uncertainty surrounding any innovative process, but are above all due to the vastness of the problem that is not easily defined in concrete terms as regards types of waste and number of operators involved.

Humans↗
PubMedDate not supplied

[Acute exposure to vanadium-containing dusts: the health effects and biological monitoring in a group of workers employed in boiler maintenance].

The authors describe an episode of acute intoxication due to inhalation of vanadium-containing dusts in a group of 10 workers during maintenance work inside a boiler of an oil-fired electricity power station. Historical, clinical and biological monitoring data concerning the acute exposure phase and subsequent checks are presented. The appearance of irritative symptoms of the upper airways, green tongue (in 6 out of 10 subjects) and the values of urinary excretion of vanadium (means = 92, D.S. = 47 micrograms/l: limits 20-270 micrograms/l) indicated acute vanadium exposure. With the use of appropriate individual protection devices and shorter shifts, 2 weeks after the episode there was a complete remission of the symptoms and a return of urinary vanadium concentrations to 38, D.S. = 26 micrograms/l. Checks made 6 months, 1 and 2 years later did not reveal any alterations in the general blood chemistry parameters and the urinary vanadium concentrations were below 1 microgram/l (reference value). As already often reported in the literature, this episode confirms the danger involved in working in the presence of fuel oil residues or ashes and the need to adopt appropriate prevention measures.

Acute Disease↗
PubMedDate not supplied

[An integrated course in occupational medicine. A proposed teaching program based on the new organization of the degree course in medicine and surgery].

The curriculum of Italian Medical School of the Faculty of Medicine has been recently renewed at a national level. Considering the numerous innovations introduced, a new role has been attributed to the teaching of occupational health, particularly occupational medicine. Occupational Medicine is usually regarded as a part of community medicine and, despite the fact that occupational disease may be in decline in industrially developed countries, the increasing concern regarding environmental pollution related health effects, stress the relevance of the methodologies already formulated within the occupational health disciplines. Of all environmental factors, occupational medicine has contributed largely to the knowledge about the health effects of occupation and its role in the complex problem at work related to today's medical students as a way of introducing the appreciation of worldwide environmental effects and how to measure, monitor and modify them. In this article the content of the occupational health course is revised and according to the principles of modern medical pedagogy, the teaching is divided in primary and secondary objectives and organized to the resolution of real problems. The importance of the relevant evidences of clinical occupational medicine is discussed and their insertion into other clinical disciplines is proposed. The knowledge of distribution, recognition, management and prevention of the major occupational diseases is a final target of the teaching. The introduction of innovative teaching methods such as factory visits, case history discussion or role playing exercises is suggested as an integrated, multidisciplinary approach able to promote the preventive attitude of students. The efficacy of the teaching has to be evaluated with appropriate methods every time, to verify both informative and formative aspects.

Curriculum↗
PubMedDate not supplied

[Determination of blood bile acids using high pressure liquid chromatography: comparison of chromatographic, enzymatic and immunoenzymatic methods].

A method has been developed for measuring serum conjugated bile acids by HPLC. Serum samples, to which the internal standard is added, are purified by a solid phase procedure and injected on a reverse phase C18 column. Elution is accomplished by means of a flow gradient and peaks are detected at 198 nm. The detection limit ranges between 0.05 and 0.20 mumol/l for different analytes; between-day precision (CV 5.8%), working linear range (up to 50 mumol/l) and recovery (87%) were established. Comparison of the results obtained with HPLC, enzymatic and immuno-enzymatic methods gave high correlation coefficients. The method was applied for diagnostic purpose to a group of subjects suffering from various liver diseases. Also, 106 healthy workers, not occupationally exposed to known or potentially hepatotoxic agents, were studied in order to establish reference values for use in biological monitoring of chronic low level exposure to solvents. The method has the advantage of a more simple procedure compared to previously reported HPLC methods and appears to be well suited for routine use in toxicological and clinical test laboratories.

Adult↗
PubMedDate not supplied

[Biological limits of exposure: evolution of interpretative and methodologic criteria].

Biological monitoring is an extremely efficient investigation tool in evaluation of exposure to exogenous substances, in both occupational and environmental settings. However, although biological tests have been widely acclaimed as the ideal approach to or as a completion of environmental measurements, they have had difficulty in becoming firmly established due to a number of limitations of various nature. Besides the numerous uncertainties in the set-up phase, which depend on the choice of indicators or criteria for their use, difficulties are still incurred in making a univocal interpretation of the results. These difficulties are due to the limited pharmaco-kinetic information available on the various substances and to the wide variability in individual biological response. The possibility of extrapolating Biological Exposure Limits (BELs) from the corresponding TLV-TWA, by means of calculations based on the experimental regressions observed between internal and external dose indices, has up to now been considered a dubious operation from a formal point of view and merely indicative for practical purposes. This paper examines the possibility of establishing BELs that are fixed taking account of the influence of the various biological variables, thus permitting a more correct, objective and generalised use of biological indicators in current practice. From the regression function and relative tolerance limits, intended as a range of values within which regression values can be expected to be found with a probability that can be fixed a priori, it is possible to calculate 3 BEL values for each environmental TLV-TWA concentration. The question of which of these different values should be selected as a BEL for practical purposes must be solved on the basis of a series of observations related to the type of investigation being performed and the context in which the results are to be used. It should be emphasized that each BEL value has its own particular sensitivity and specificity, i.e., the possibility of correctly classifying the exposure conditions in relation to the environmental values. If sensitivity and specificity values are known, it is possible to calculate the predictive value of the biological measurements compared to the environmental measurements; if numerical data on these parameters are available, account can be taken of the variability of the results in a rigourously scientific manner.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants, Occupational↗
PubMedDate not supplied

[Biological monitoring of occupational exposure to airborne pollutants].

Biological monitoring of inert substances requires knowledge of the mechanisms regulating respiratory absorption. The authors examine the influence of parameters such as work load, exposure duration and biotransformation on the respiratory absorption of inert airborne pollutants in the workplace. Attention is also given to the possibility of using biological thresholds or Biological Equivalent Limits (BELs).

Air Pollutants, Occupational↗
PubMedDate not supplied

[Application of high-pressure liquid chromatography in the analysis of urinary metabolites of aromatic solvents].

The introduction of HPLC methods in industrial toxicology represents a valuable tool for the routine monitoring of workers occupationally exposed to aromatic solvents. The HPLC method described here permits the simultaneous determination of metabolites of ethylbenzene, styrene, toluene, xylene isomers, benzene, phenol and cresol isomers in diluted urine samples. Pretreatment of urine samples with steam distillation is necessary only for determination of phenol and cresols because of their low concentrations. A comparison between a GLC and the HPLC procedure for mandelic and phenylglyoxylic acids confirmed the satisfactory performance of the HPLC method.

Adult↗