Biomedical subjects
Publications and source records attributed to A Cristea.
The formalisms of the probability distribution and of the associated generator function are used to establish the equations for the first and second moments of the numbers of susceptible and contagious individuals. Applications are given for the linear cases for the epidemic evolutions, for the endemic situations and for virosis in course of eradication.
Data on clinical features and laboratory diagnosis of familial antithrombin deficiency, a rather heterogeneous group of disorders, are illustrated by observations on two Romanian kindreds afflicted by recurrent thrombotic episodes. In a first family, both plasma antithrombin III antigen and activity were reduced to 50% of normal, a condition characteristic for a heterozygous type I (quantitative) familial antithrombin III deficiency. In a second kindred, the two brothers who had experienced thrombotic events since they were teenagers, displayed exceedingly low AT III heparin cofactor activity (13% and 16% of the normal, respectively) while values around 50% of the normal were recorded in their parents who had not experienced thrombotic episodes. Since plasma antithrombin III antigen and total progressive antithrombin III activity were within normal limits in all the investigated members of this family it was considered that the two brothers were homozygotes or compound heterozygotes and the parents were heterozygotes for a qualitative-antithrombin III deficiency caused by an abnormality of the heparin binding site.
The individuals are distributed in 9 risk groups (adults and children), in which an HIV transmission way is predominant. Taking into account a simplified graph of the HIV infection evolution, kinetic equations for the number of individuals from each risk group--situated in various stages of HIV infection--are written. The approximative solutions of these equations give us: the characteristic exponents of the temporal evolutions of the main and secondary local epidemics; the ratios Ci/Bi and Di/Bi of asymptomatically contaminated and dead (as consequence of AIDS) versus symptomatically contaminated; the onset of local epidemics in various risk groups; the relative amplitude of the secondary local epidemics versus the main local ones.
The present study was designed to evaluate the urinary albumin excretion in 62 patients with essential hypertension. None of them had prior proteinuria or history of nephropathy or uropathy. Patient data, blood pressure, proteinuria using Bradford's method, albuminuria by radial immunodiffusion, urinary SDS-PAA electrophoresis, plasma glucose, serum creatinine, serum cholesterol were determined. The urinary albumin excretion was significantly higher (p < 0.001) in the group of hypertensive patients (19.22 +/- 2.36 micrograms/min) compared to a group of 20 control subjects (4.17 +/- 0.67 microgram/min). Compared to a subgroup of hypertensive patients without ischemic heart disease (12.07 +/- 1.30 micrograms/min) microalbuminuria was higher (43.74 +/- +/- 5.74 micrograms/min; p < 0.001) in a subgroup of 14 patients with essential hypertension and ischemic heart disease with severe coronary events: unstable angina pectoris (9 patients), myocardial reinfarction (2 patients), ventricular arrhythmias (3 patients). A positive correlation between the microalbuminuria and the duration of hypertension was found (r = 0.64; p < 0.001). Therefore, microalbuminuria may represent a marker of the severity of vascular involvement in hypertensive patients.
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We present a new class of autoantibodies--ANCA (antineutrophil cytoplasmic autoantibodies) which recognize as target antigen different enzyme constituents of primary granules of neutrophil granulocytes. These autoantibodies are present in a large number of diseases, such as: systemic vasculitides, idiopathic crescentic glomerulonephritis, inflammatory bowel diseases and in some other conditions, including rheumatoid arthritis, SLE, Felty syndrome, acute and chronic infections. ANCA not only facilitate the diagnosis but also have a pathophysiological role for some of the idiopathic vasculitides. In our study, including 110 patients referred to the laboratory for ANCA testing by indirect immunofluorescence technique, only 25 patients were positive with a diffuse cytoplasmic (c ANCA) or perinuclear (p-ANCA) pattern on alcohol fixed slides. Some relevant cases are presented in order to emphasize that ANCA antibodies are a useful marker in the early diagnosis of systemic vasculitides, allowing effective therapeutic handling.
The clinical research was made on two groups of young volunteer students. We considered stress consisting in chronic informational overexposure during the examination session and the acute stress from their emotions before a hard examination. The painful sensitivity was analysed by measuring the retraction time of the finger from water at 55 degrees C. The experimental research was made on a group of 100 male mice. The acute stress was performed by subjecting each mouse to swim (behavioral despair test). Painful sensitivity was determined by the test of the hot plate heated at 50 degrees C. Individuals with hyper (H) and hypo (h) painful sensitivity were selected for the tests. In chronic stress, the results proved increased painful sensitivity (hyperalgia) more important at "h" compared to "H" (p < 0.05). In acute stress decreased painful sensitivity (stress analgesia) was noticed more significant at "H" compared to h" (p < 0.05). All these results suggested that the extreme "H" and "h" are two different stress behaviors with opposite mechanisms involved in stress analgesia. This hypothesis is related with studies which demonstrate the involvement in stress analgesia of non-opioid monoaminergic mechanisms together with the opioid mechanisms (Lewis, 1980).
We have emitted the hypothesis that the double-way effect is possible not only due to the wide range of receptor substrates and receptor subtypes but it can manifest at the heterosynaptic and synaptic cotransmission level as a consequence of the informational unbalance which very low or very high doses of biological signals (in pathological disorders) or of drug signal (agonist or antagonist) can do on physiological balance between both two coupled synaptic systems. To verify this hypothesis we choosed as place of manifesting and observing of the phenomen the informational gearing between the endogenous opioid system as "modulator" and the catecholaminergic systems as "alarm". As drug signals we used naloxone (NALX) and clonidine (CLON). The function studied to reveal the double-way effect was stress analgesia monitored in the classical test of te "hot plate". The experimental stress was induced to the mouse by submitting to forced swimming using the "despair test". In the work are presented the dose-effect curves and inflexion points which mark the changing of the sense of the effect.
A generalized neural network was adapted for the simulation of processes strongly dependent upon the history, imposed by the inner own history of an individual neuronal activation. This involves the dependence of the neural network parameters upon the cumulated values of the corresponding neuron activations. When in the neural network weakly coupled blocks with strong inner couplings can be identified, the activation wave on the entire network (associated with the overall epidemic) can be decomposed into quasi-independent intra-block local activation waves, with characteristic delays between them (corresponding to the simultaneous and successive local epidemics). Special simulations on strongly connex neural network determine the typical local activation waves for various block parameters and the mentioned delays between two such successive activation waves in two coupled blocks. Another type of neural network is used to achieve the empirical decomposition of the overall epidemic into simultaneous (corresponding to a layer) and successive local epidemics (corresponding to the various epidemic waves, associated with different layers). A simpler approximative algorithm for the estimation of the number of the mentioned simultaneous local typical epidemics is also presented.
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It was studies the content of nitrates and nitrites in water sources and vegetables from different geographical regions, resulting high values of nitrates in colinae and plain regions, and low values in mountain and submountain region. The high value of nitrates are related with methaemoglobinaemia. The nitrites from edible water studied and from vegetables presented very low values in the order of ppm.
The individuals are distributed in 9 risk groups (adults and children), in which an HIV transmission way is predominant. Taking into account a simplified graph of the HIV infection evolution, kinetic equations for the number of individuals from each risk group--situated in various stages of HIV infection--are written. The approximative solutions of these equations give us: the characteristic exponents of the temporal evolutions of the main and secondary local epidemics; the ratios Ci/Bi and Di/Bi of asymptomatically contaminated and dead (as consequence of AIDS)--versus symptomatically contaminated; the onset of local epidemics in various risk groups; the relative amplitude of the secondary local epidemics versus the main local ones.