Ion-beam effects on optical and rheological properties of polystyrene.
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Biomedical subjects
Publications and source records attributed to G Foti.
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We evaluated the airway occlusion maneuver as a method to estimate respiratory resistance, respiratory elastance and the pressure generated by respiratory muscles in ICU patients breathing in the PSV mode. The airflow was interrupted at selected flows or volumes during inspiration by a computer-driven rapid occlusion pneumatic valve. The airway occlusion was maintained for 2 to 3 s. From the airway pressure tracing we obtained various measurements of pressure. We then computed the pressure generated by the patient's inspiratory muscles. The method was validated by two different approaches in two groups of patients: the Pes and the CMV protocols. We conclude that the airflow interruption method can be used to measure basic respiratory mechanical parameters in PSV patients. The method also offers an opportunity to evaluate Pmusc,aw and the respiratory work performed by the patient.
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Fluorine content in dental tissues has been measured by using nuclear reactions with high energy proton beams and detecting alpha particles and/or gamma rays emitted from fluorine nuclei. The sensitivity of the nuclear analysis reaches 0.1 mg/g and the depth distribution of fluorine atoms can be determined up to 5 mum. The depth resolution is about 0.3 mum with alpha particles and 0.1 mum with gamma rays. Distributions of fluorine both in surface enamel and in cross section of teeth were measured by using a proton probe 500 mum in diameter. A systematic increase in the fluorine concentration has been observed in the healthy incisors dental enamel (1-3 mg/g) with respect to the molar ones (0.5-1 mg/g). A comparison between the fluorine content in healthy teeth and in pathological ones was made.
Personal experience with a series of 69 cases of non-A, non-B viral hepatitis out of 164 cases of acute viral hepatitis observed at hospital admission between January 1985 and June 1988 is reported. Agreement is expressed with other Italian series as regards the incidence of sex, of the most involved age classes, of the most affected professional categories and of the incubation period of posttransfusional forms. The prevalence of sporadic forms over those transmitted intraparenterally and more prolonged course in icterus patients and in parenteral forms is pointed out.
A case of central nervous system toxoplasmosis is reported. Attention is called to the diagnosis of this infection; moreover, the authors emphasize the importance of the TAC brain for the diagnosis and evaluation of the clinical evolution and response to the therapy.
We performed long-term closed-chest cardiopulmonary bypass in an animal model of total heart failure (induced ventricular fibrillation). The extracorporeal system included a venous reservoir, a roller pump, a membrane lung, and a blood pulsator system. We cannulated the right external jugular vein for venous drainage and the right subclavian artery for arterial return. To decompress the left heart we passed by percutaneous cannulation a special helical spring mounted on a Swan-Ganz catheter (Baxter Edwards Divisions, Irvine, Calif.) and positioned it to rest within the pulmonary artery and tricuspid valves, which rendered them partly incompetent. After induced ventricular fibrillation, blood flow was raised to keep the central venous pressure at baseline values. The lungs were ventilated with 5% carbon dioxide in room air. During bypass, mean pulmonary artery pressure was 10.0 +/- 1.7 mm Hg, mean wedge pressure 11.9 +/- 1.8 mm Hg, and mean blood pressure 95.2 +/- 5.6 mm Hg. After 2 days (four animals) and 3 days (two animals) the hearts were defibrillated. There was immediate ejection from both sides of the heart. All sheep were weaned from bypass within 29 +/- 11 minutes and their lungs were ventilated with room air within 42 +/- 34 minutes. At autopsy hearts and lungs grossly appeared normal. We conclude that the percutaneous helical spring resting within right heart valves provided excellent decompression throughout the study, with full recovery of heart and lung function on defibrillation.
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The Authors report a case of leptospirosis. Stress is laid on the sporadicity of this infection in their region; attention is also drawn to the variety of the clinical expression of this disease.
A case of visceral leishmaniasis in a female patient suffering from acute nonlymphoid leukaemia is reported. Stress is laid on the atypical nature of the clinical picture, falsified by the underlying disease, and attention is called to the behaviour of Leishmania as an opportunistic agent in the immunodepressed host.
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The volume/pressure (V/P) curve of the total respiratory system in paralysed patients is drawn assuming that volume changes of the respiratory system (delta V resp) equals volume displacement of the measuring apparatus (delta V syr), usually a supersyringe. However, in 93 VP curves we found that O2 removed from the lung-syringe system during the procedure (proportional to the time) largely exceeds the CO2 added to the lung-syringe system (delta V gas). This results in a net loss of volume from the system (delta V resp less than delta V-syr). Deflation compliance, hysteresis area and ratio are significantly affected by this phenomenon. Inflation compliance is less influenced by delta V gas, partially compensated by the intrapulmonary gas expansion due to the temperature changes. We conclude that the parameters computed on the deflation limb of V/P curve are misleading if proper correction of the volume scale is not introduced.
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