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Biomedical subjects

A Cristea

Publications and source records attributed to A Cristea.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Cortisol circadian rhythm in 70--100-year-old subjects.

The circadian rhythms of plasma cortisol was examined in 25 persons aged between 70 and 100 years by comparison with 5 adults aged between 17 and 38 years. The blood samples were drawn at 16 hundred, 20 hundred, 00 hundred, 04 hundred and 08 hundred hrs. Cortisol was assayed by the fluorimetric method. The experimental data were analyzed by Halberg's mean-cosinor method. The results showed that the circadian rhythm in plasma cortisol changes with age. The characteristic phenomena found were the following: a tendency towards reducing the hourly quantitative differences, comparatively more marked between 90 and 100 years; anticipation of the cortisol maximum level of 08 hundred at 04 hundred hrs in the group of 71 to 80 years, and at 00 hundred hrs in some of the subjects older than 80. A normal circadian rhythm was found in 2 of the 25 cases examined. These changes imply variations of the same kind in the CRF and ACTH levels. The changes in the circadian rhythms of cortisol show that the regulation systems are also implied in the aging process. It is possible that early-morning insomnia of the aged be due to this anticipation in cortisol secretion.

Adolescent↗
PubMedDate not supplied

Immunologic alterations associated with chronic hemodialysis.

Parameters of humoral immunity were studied in 18 patients with chronic renal failure undergoing hemodialysis. IgG, IgA and IgM serum levels presented no differences compared with healthy donors. High immunoglobulins levels were found in 40 patients with chronic renal failure and conservative treatment. Complement components C1q, C4, C9, were normal, but C3 and C3A were significantly low prior to dialysis. During hemodialysis, the complement system showed an activation by the alternative pathway (AP). The cuprophan membrane was proved to be an important factor in this activation. The circulating immune complexes (CIC) were also high. Seven patients presented autoantibodies, 2 against smooth muscle and 5 against gastric parietal cells. Our results suggested a certain humoral immune alteration during chronic hemodialysis.

Antibody Formation↗
PubMedDate not supplied

Evaluation of the prematurity risk on the ground of severity scores reflecting the action of different factors, maternal virus infection included.

A mathematical methodology is suggested which allows the a priori calculation of the risk of premature delivery, by a formula relying on the scores attributed to different specific risk factors (maternal virus infections included). The scores are estimated either directly, or starting from the scores of nonspecific factors. The statistical significance of the different scores, correlations and formulas is analyzed.

Adult↗
PubMedDate not supplied

Study of antibodies against viruses, chlamydiae, rickettsiae and Mycoplasma pneumoniae in children with respiratory diseases.

Seroconversion to different viral, chlamydial, rickettsial and mycoplasma antigens was followed up in 134 children aged 0-6 years, hospitalized with different respiratory diseases. Parainfluenza viruses type 1, 2 and 3 and adenoviruses appeared to be involved in the etiology of most of the cases; respiratory syncytial virus was often found to play a role in pneumonia/bronchopneumonia and in "influenza-like illness", while chlamydiae and M. pneumoniae could be incriminated in cases of "influenza-like illness", as well as in the other categories of respiratory disease. Mixed infections with the agents studied could be detected.

Antibodies, Bacterial↗
PubMedDate not supplied

Detrimental effects of hepatitis B virus infection on the development of the product of conception.

Frequent reproductive casualties (spontaneous abortions, stillbirths, prematurity and low birth weight, congenital malformations) were recorded in a group of 264 women who had viral hepatitis (VH) during pregnancy. The proportion of such events was much higher in the HBsAg-positive women (80%) than in the seronegative ones (44%) and it varied according to the trimester when VH had occurred. Liver disease could be incriminated as the main cause of infant death in 20 out of 2110 cases investigated; 6 of the 20 mothers proved to be HBsAg-positive. Asymptomatic HBsAg carriage in a group of 3800 pregnant women was found to be of about 8%; the prevalence of HBsAg was higher in the subgroups of women with an unfavourable pregnancy evolution.

Abortion, Spontaneous↗
PubMedDate not supplied

Statistical studies on the epidemiology of human congenital malformations. Implications of maternal virus infections.

Prospective and retrospective statistical studies were performed in 1,000 cases of congenital malformations. The incidences and severity of the different types of malformations were correlated with the risk and protection factors having acted on the pregnant woman. The correlation coefficients were higher in the case of specific risk factors, among which special attention was paid to maternal virus infections. The possibility is discussed of developing a programme for the individual protection of high-risk cases, implying the compensation of the exposure to risk factors by the application of adequate protection factors, according to the calculated scores.

Congenital Abnormalities↗
PubMedDate not supplied

Mathematical model of virus disease morbidity evolution in communities with several components.

Mathematical models previously developed for the evolution of virus disease morbidity in communities with a single component are generalized so as to be applied to the case of communities consisting of several coupled components. Epidemiological characteristics are discussed in the case of components linked by weak, strong or intermediate couplings. A detailed analysis is made of the cases when the different components are represented by; a) different geographical areas; b) different types of sources of infection; c) different age groups.

Age Factors↗
PubMedDate not supplied

An algorithm for the optimization of programmes aimed at the prevention and control of virus diseases.

A new algorithm is developed for the optimization of long-term programmes for the prevention and control of virus diseases. Relatively simple formulae are written for the optimum numbers of antiepidemic services, the minimum cost of the programmes and for the sensitivity of the optimization criterion to errors in the estimation of the optimum numbers of services. The efficiency of the algorithm is illustrated by an example referring to antimeasles vaccination campaigns.

Humans↗
PubMedDate not supplied

Experimental model of psychic stress.

An experimental model for the induction of an informational psychic stress in the rat, comparable with the psychic stress in man, is described. The method consists in the production of the emission of significant acoustic signals by an "emitting" group of animals, subjected in an aleatory manner to electroshocks. The acoustic nociceptive signals are heard by a "receiving" group of animals. In this "receiving" group are studied the behaviour and the neuroendocrine changes. This experimental model may be useful for studies of psychopharmacology, for the research of psychotropic drugs and for the determination of their action upon the harmful effect of informational aggressions and psychic stress.

Animal Communication↗
PubMedDate not supplied

Endogenous opioid abstinence syndrome.

Starting from the observation that an increase of stress analgesia is followed by a hyperalgesia period, with a series of symptoms characteristic of the exogenous opioid abstinence syndrome (EXOAS), the authors supposed also the possibility of the existence of an endogenous abstinence syndrome (ENOAS). In order to demonstrate the existence of this syndrome, they investigated at first the possibility of the appearance of an acute tolerance to opioids. Then they followed-up the course of behaviour during and after informational stress in untreated animals, in animals treated with naloxone, which--being an antagonist of opioids--can induce EXOAS in toxicomaniacs, and in animals treated with clonidine and propranolol, that are used in the treatment of EXOAS. Experimental researches have demonstrated the possibility of ENOAS occurrence, its aggravation by naloxone and its improvement with clonidine and propranolol.

Adaptation, Physiological↗
PubMedDate not supplied

Correlation between fibronectin and cardiothoracic ratio in heart failure treated with angiotensin converting enzyme inhibitors.

A group of 17 patients with ischemic heart disease, significant left ventricular dilatation and congestive heart failure, class III NYHA (9 patients) and class IV NYHA (8 patients) was studied. The patients received angiotensin converting enzyme inhibitor--captopril 75 mg/day or perindopril 4 mg/day--added to diuretics, digitalis and nitrates. The plasmatic level of fibronectin was investigated, by radial immunodiffusion, before and one month after the beginning of the treatment with angiotensin converting enzyme (ACE) inhibitor. The plasmatic level of fibronectin is increased significantly (p < 0.001) while the cardiothoracic ratio is decreased significantly (p < 0.02) after one month of ACE inhibitors treatment. A positive correlation between the increase of the plasmatic level of fibronectin and the decrease of cardiothoracic ratio is found (r = 0.62; p < 0.01). The increased fibronectin plasmatic level can be a marker of the favorable effect of ACE inhibitor on the myocardium interstitium.

Angiotensin-Converting Enzyme Inhibitors↗
PubMedDate not supplied

Simulation of a viral epidemic by means of a neural network.

The neurons of the network used for the simulation of a viral epidemic correspond to the individuals of the community. The activation state of the neurons reflects the contagious state of the diseased persons. Variable thresholds are introduced for the differentiation of the neuronal non-activation states (susceptible or immune subjects). The thresholds are calculated depending on the cumulated values over time of the neural activation states. The network functions synchronously. In order to follow up the state of the neural network, recurrence relations were introduced. They were applied in two epidemiological situations which differ from each other by the spreading intensity of the virus over time, reflected by the particular values ascribed to the elements of the neural connection matrix.

Child↗