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Biomedical subjects

C Clerici

Publications and source records attributed to C Clerici.

65 records · Page 4Linked to original sources
PubMedDate not supplied

Endoscopic treatment of bile duct stones.

Approximately fifteen per cent of patients who undergo gallstones also have concomitant common bile duct stones. Endoscopic papillosphincterotomy (EPS) is the treatment of choice for common bile duct stones in cholecystectomized patients as well as in patients with gallbladder in situ but at high operative risk. Endoscopic papillosphincterotomy is a highly effective technique and able to remove stones from choledochus in 85-90% of cases. The failure of EPS is mainly related to the size of stones (greater than 15 mm). However, recently introduced sophisticated techniques, such as extraluminal (extracorporeal shock wave lithotripsy) or intraluminal lithotripsy (mechanical, electro-hydraulical or laser) now allow to fragment and remove also "large" stones. Should EPS fail to remove stones, a naso-biliary tube can be endoscopically positioned and attempts made to dissolve the stone by infusing chemical solvents. However, until now the chemical dissolution has only a marginal efficacy in the treatment of common bile duct stones. If all these techniques fail, good operative risk patients can be treated by surgical choledochotomy, while high operative risk patients can be treated by permanent biliary endoprosthesis or percutaneous techniques.

Acute Disease↗
PubMedDate not supplied

[Sensitivity, precision and resolution of the optical microscope in the study of environmental pollution by asbestos fibers].

The authors comment on the methods and equipment used in two Italian laboratories for sampling and microscopic phase contrast analysis of asbestos and other respirable fibres in the air of the general environment, i.e., the Dust Analysis Laboratory, Industrial Hygiene and Toxicology Department of the Institute of Occupational Health (Clinica del Lavoro), University of Milan and the Technical Microscopy Laboratory, Ground Resources and Land Control (Georisorse e Territorio) Department of Turin Polytechnic, which use identical methods. Airborne dust samples are taken with personal samplers, 1 l/min air flow (sample duration 4-8 h), filtering air on 25 mm diameter, 0.8 micropore cellulose filters (about 300 mm total net surface of dust deposit). The following equipment is used for counting and analysis of fibres: a) Clinica del Lavoro, Milan: Polyvar Reichert-Jung microscope, 500 magnitudes, Zernike positive phase contrast; numerical counting on 100 whole ocular fields, equal to 6.38% of the total net surface of dust deposit on the membrane; b) Turin Polytechnic: Leitz Ortholux microscope, 500 magnitudes, Heine and Zernike phase contrast with mean standard contrast; numerical counting on square grid, with explored surface total equal to 1.68% of the total net surface of dust deposit on the membrane. Measurements performed: Clinica del Lavoro, Milan: 2,980 since 1960; Turin Polytechnic: 875 since 1965. The sensitivity of the methods for counting airborne fibres is discussed, concluding that the methods used by the two laboratories have a sensitivity between 0.05 and 1.6 fibre/litre of air, according to the overall dustiness of the environment under study. Analysis of the accuracy of the optic determinations, based on the repeated counts, shows a repeatability of 0.4 (40%) within 95% confidence limits. A resolution power of 0.35 microns is reported; however, the possibility exists (and is normally achieved in analytical practice in both laboratories) of identifying and counting fibrous elements up to 0.1-0.3 microns in diameter; this is possible in particular conditions, i.e., when there is a marked difference between the "mean" refraction index of the fibres and that of the diaphanizing liquid. For qualitative determinations of the various types of asbestos, however, analyses are limited to diameters greater than 0.5-0.8 microns, since it is necessary to be able to assess optical properties (refraction indices, basically). In the concluding discussion, comments and bibliographic references are also given concerning the comparisons with possibilities of studying fibrous particulate matter via electron microscopy.

Air Pollutants↗
PubMedDate not supplied

[Effects of histamine on the pressure-volume curve of the respiratory system in the guinea pig].

Intravenous infusion of histamine has been shown to constrict smooth muscle of alveolar ducts. In this study, we have assessed the effects of a prolonged infusion of histamine to obtain a steady state response on quasistatic pressure-volume curves (P-V curves) together with the changes in dynamic compliance (Cdyn) and conductance (G) of the respiratory system. Increasing doses of histamine were given in order to obtain the dose-response characteristics of the changes in Cdyn, G and P-V curves. In nine anesthetized guinea-pigs under mechanical ventilation, administration of histamine resulted in a fall in Cdyn and G with a decrease of 50% of initial value approximately for 150 ng X kg-1 X s-1 of histamine. Modifications of the P-V curves were characterized by a decrease in the maximal volume, and an increase in the hysteresis of the P-V loop due to the downward displacement of the inflation limb. With infusion of histamine, there was a large decrease of quasi-static compliance which appeared to account for most of the decrease in dynamic compliance. Such changes in P-V curves can be related both to a closure of alveolar ducts and to an alteration of lung distensibility. Comparison of the dose-response curves for the different parameters indicated that Cdyn and G reflect, at least in part, events occurring in the periphery of the lung.

Animals↗
PubMedDate not supplied

[Chronic therapy with ursodeoxycholic acid in a child with Alagille syndrome].

The effectiveness of oral bile acid therapy with ursodeoxycholic acid (10 mg/kg/day) was investigated in a 10 year old boy affected by Alagille's Syndrome, a chronic cholestatic disorder due to congenital hypoplasia of the intrahepatic biliary ducts. Cholestatic and hepatonecrotic indices were measured before and during ursodeoxycholic acid therapy and 1 month after stopping and 36 months after restarting the treatment. Ursodeoxycholic acid led to a marked improvement in the cholestatic and hepatonecrotic parameters which was maintained during all the treatment phase. Pruritus and steatorrhea disappeared during the treatment with ursodeoxycholic acid. Histological examination of the liver biopsy after the treatment revealed a disappearance of the biliary plugs but without increasing he intrahepatic bile ducts. The results suggest that ursodeoxycholic acid may improve the condition of the children affected by Alagille's Syndrome, specially when the liver transplantation is required, and indicate a need for long term studies in a larger number of patients.

Bile Ducts, Intrahepatic↗
PubMedDate not supplied

[Optical and electron microscopic methods for counting respirable fibers of asbestos: considerations on relative standards].

The paper reports experience of the use of optical and electronic microscope methods for assessment of the concentration of airborne asbestos fibres and their respective identification. The results described are derived from the extensive experience of three Italian university institutes, which have used optical methods of observation for over 35 years (phase contrast technique, at times associated with the use of polarized light) and have examined altogether about 11,000 samples of airborne dust and fibres. After considering in more detail certain values of asbestos fibre concentrations in various environments, measured parallely with optical and electronic microscope, and assessing their basic comparability, attention is drawn to a number of ambiguities and contradictions contained in Law D.M. 6/9/1994, which tends to discourage the use of the optical microscope (especially using the phase contrast technique), without however taking into consideration the improved cost/benefit ratio in the assessment of respirable asbestos fibres present in working and living environments. On this topic, attention is drawn to the fact that the limits for occupational exposure to asbestos, proposed and/or adopted in the international scientific literature, are based on the numerical count of fibres with the optical microscope using the phase contrast technique (MOCF).

Air Pollutants↗