[Blood levels of vitamin E, polyunsaturated fatty acids of phospholipids, lipoperoxides, glutathione peroxidase activity and serological screening for syphilis and HIV in immigrants from developing countries]

Plasma levels of vitamin E (Vit E), polyunsaturated fatty acids of phospholipids (PUFA-PL), lipoperoxides as well as erythrocytes glutathione peroxidase activity (GSH-Px), were evaluated in 200 migrants coming from developing countries, some of which at high risk for serious infective diseases. HIV-1 and syphilis infections were also investigated. 114 subjects (57%) had blood levels of Vit E, PUFA-PL and GSH-Px significantly lower (p less than 0.001, p less than 0.01) than those of normal healthy individuals (n = 30), while lipoperoxides values were unchanged. 8 from this group were found to be HIV-1 positive, and 5 TPHA positive. In contrast, the remaining 86 migrants did not show any signs of infections and their blood parameters were normal enough. These results show that factors such as widespread poverty, inadequate housing, malnutrition, insufficient access to medical care, psychological stress are strictly correlated to the reduction of blood parameters which are critical for the normal cell function of mammalian cells. PUFA-PL deficiency may cause lesions likely due to faulty cellular membranes. The lack of Vit E and GSH-Px, which are considered major protective molecules against lipoperoxidation damage in vivo, has been involved in several human diseases. We suggest that low blood levels of Vit E, GSH-Px and particularly PUFA-PL may play a pathogenetic role in the onset and development of AIDS and other infections. In this connection, we have found that a deficiency of these blood parameters occurs in patients with AIDS (n = 50) and in 32% of HIV seronegative intravenous drug abusers (n = 100).

Intestinal occlusion: morphological features

In this research we studied the possible relationships between the level and the distribution of peroxidase-catalase activity and the degree of the morphological changes in the intestinal wall during mechanical occlusion. These researches have really proved that the increase of the peroxidase-catalase enzymes correlate proportionally with the damage of intestinal wall.

Intestinal ischemia: morphological features--II

Superoxide radicals produced during acute intestinal ischemia are biochemically related with the presence of hydrogen peroxyde. In this study we have investigated the distribution of peroxidase-catalase activity, histochemically determined, in the ischemic ileal wall. In the rat, complete arterial and venous occlusion produced a progressive increase in extra-vascular peroxidase-catalase activity with a maximum corresponding to the ileal wall. Probably the tissue peroxidase-catalase activity is related to massive degranulation of polymorphonucleates.

Intestinal ischemia: morphological features--I

In this research we studied the interrelationships between the progression of morphological damage and leucocyte populations in the last ileal loop after blockage of blood supply subsequent to arterial and venous occlusion. Our morphological data on the staging of the ileal wall damage agree with those reported in literature. In addition we described that in the ischemic loop the number of lymphocytes appear decreased and polymorphonuclear cells degranulate actively.

In vivo platelet hyperreactivity, another risk factor for patients under continuous ambulatory peritoneal dialysis

A high mortality rate due to thromboembolic accidents has been described in patients undergoing chronic haemodialysis. This type of complications, although recognized, has not been appropriately evaluated in continuous ambulatory peritoneal dialysis patients. The present study demonstrates that continuous ambulatory peritoneal dialysis patients present in vivo platelet hyperreactivity, as evidenced by enhanced platelet responses to epinephrine ex vivo and an increased MDA/MDAa index which traduces a decreased threshold for activation of the arachidonate pathway and subsequent thromboxane production. Since the etiopathogeny of this platelet abnormality seems to be related to abnormalities in lipid metabolism, compounds such as fish oil must be beneficial in the management of this risk factor.

AR identification and spectral estimate applied to the R-R interval measurements

The methods of identification and spectral estimate are applied to the tachogram, i.e. the time series constituted by the cycle-by-cycle R-R interval durations measured on the ECG signal from cardiological patients in ambulatory rehabilitation training after episodes of myocardial infarction or ischemic disease. The Batch Least Squares Method is applied to identify the series as an AR process of 5th order. The whiteness test and Rissanen's optimization criterion are also fulfilled. The clinical information is in this way highly compressed in the pole diagram and in the Maximum Entropy Spectrum (MES) estimated on the basis of the AR coefficients. The experimental results in a restricted set of patients confirm the feasibility of new instrumentation design criteria for non-conventional R-R intervals parametrisation, successive diagnostic classification and beat prediction. Finally, some preliminary considerations about the capabilities of the introduced methods put into evidence the role of computerized techniques in recognizing the fundamental patterns of physiopathological heart rate variability, which the usual conventional methods of ECG analysis are not able to detect in a reliable way.

An optimal linear filter for the reduction of noise superimposed to the EEG signal

In the present paper a procedure for the reduction of super-imposed noise on EEG tracings is described, which makes use of linear digital filtering and identification methods. In particular, an optimal filter (a Kalman filter) has been developed which is intended to capture the disturbances of the electromyographic noise on the basis of an a priori modelling which considers a series of impulses with a temporal occurrence according to a Poisson distribution as a noise generating mechanism. The experimental results refer to the EEG tracings recorded from 20 patients in normal resting conditions: the procedure consists of a preprocessing phase (which uses also a low-pass FIR digital filter), followed by the implementation of the identification and the Kalman filter. The performance of the filters is satisfactory also from the clinical standpoint, obtaining a marked reduction of noise without distorting the useful information contained in the signal. Furthermore, when using the introduced method, the EEG signal generating mechanism is accordingly parametrized as AR/ARMA models, thus obtaining an extremely sensitive feature extraction with interesting and not yet completely studied pathophysiological meanings. The above procedure may find a general application in the field of noise reduction and the better enhancement of information contained in the wide set of biological signals.

Phenylalanine ammonia-lyase entrapped in fibers

Phenylalanine ammonia-lyase extracted form Rhodotorula rubra (IFO 1101) was immobilized into cellulose triacetate fibers made hemocompatible by physical blend with a platelet anti-aggregating agent. The entrapped enzyme could operate at physiological values of phenylalanine and tyrosine reducing their level to traces within a few hours. The optimum pH value for the entrapped enzyme shifted from 8.0 to 9.0. At blood pH the activity was about 68 per cent of the maximum. The entrapped enzyme retained its original activity in blood for more than 50 days.

Monitoring of metabolites applying fibre-entrapped enzymes in a calorimetric system. I -- Glucose and urea determination

A simple device, consisting of a heat sensor placed in close contact to fibres containing enzymes and connected to a temperature measuring unit has been developed. The system monitors the temperature variations due to the enzymatic reaction when substrate solutions flow through the measuring cell. Fibres containing the enzymes glucose oxidase and catalase for the determination of glucose and fibres containing urease for the determination of urea were tested. A linear relationship between the substrate concentration and the deltaT recorded was obtained in both cases.

Irreversible laser damage in ir detector materials

Irreversible laser damage phenomena are investigated in pyroelectric and semiconductor ir detector materials. Thermal damage phenomena in these materials are reviewed, and new results are presented. Theoretical models, which successfully describe thermal damage in detector materials, are reviewed, and criteria for the application of these models are discussed.