Romanian journal of physiology : physiological sciences最新文献

The limiting factors of top athletic performance and the psycho-physiological mechanisms involved remain controversial. The aim of this study was to attempt a prediction of world records (WR) for the next ten years in five athletic track and field and events. Our prediction has been produced by means of computer--aided mathematical models. In short, polynomials that could best approximate the WR of the last decades have been calculated and projected over the period 2000-2010. The predicted values for the year 2010 point to an improvement rate of the WR considered varying between 0.2% and 10.3%, depending on event and gender. Those values could be influenced by the use of better sports equipment, better nutrition and training and especially by the impact of doping and of anti-doping measures.

Variation of physical fitness during the day is well investigated and is used both in athletes training as well as during sports contests. Circannual periodicities, on the other hand, seem to exist but have not been investigated systematically so far. The present case report shows that absolute increase in the number of press-ups varies during the year and can be modelled by means of standard cosinor analysis. Moreover, published data dealing with circannual rhythm of muscle strength could be fitted into a cosinor model. These results indicate a circannual increase of performance and warrant further controlled investigations. Due to methodological problems in trials for circannual rhythms, population cosinor models may be a suitable approach.

The "spotting" microarray technique, consisting in large sets of DNA sequences spotted on poly-L-lysine-coated glass microscope slides, has been developed to comparatively analyze genome-wide patterns of mRNA expression. It is now a valuable tool employed in order to quantitatively monitor gene expression profiles, as well as to analyze the alterations produced in case of genetic diseases, or induced by different treatments, abnormal nutrition and toxin. Our group improved the standard protocol as well as the results spreadsheet, adding new experiments and mathematical processing procedures in order to increase the accuracy of the data and get new information. In this contribution, we propose and verify two procedures to correct the spot ratios and a new protocol to get the normal variability of the digital gene expression.

In the adult brain, astrocytes account for about 40% of the cell population in the central nervous system. Normal, reactive and neoplastic astrocytes can be identified in immunohistochemical preparations by means of glial fibrillary acid proteins (GFAP) expression. This protein is considered to be a sensitive indicator of xenobiotics toxicity. Previous studies have demonstrated that 2 mM LiCl induce alterations of astrocyte morphology after 18-20 days of treatment in vitro. We have decided to study GFAP expression under such conditions. Immunodetection and Western blotting assays have shown 2 mM of LiCl to induce alterations of GFAP expression both after 12 days of treatment and after 18-20 days. Moreover, 2 mM of LiCl induce an alteration of the proteinic composition of cells.

Ischemic hypoxia of the head induced in dogs by carotid compression produces EPO secretion, upon direct cerebral stimulation, and adaptive carotid-respiratory reflexes via sino-carotid stimulation. During hypoxic hypoxia, there also occurs extrarenal EPO production, as shown in binephrectomized rats compared to controls. Ischemic hypoxia of a single kidney transplanted in the neck area (the other kidney being removed) does not induce EPO secretion. An additional factor, of extra-renal origin, is required for the renal production of EPO in a non-hypoxic organism. Section of the spinal cord at C6 level in rats does not abolish EPO secretion induced by hypobaric hypoxia, a fact that suggests that there is no nervous center to control EPO release into a peripheral organ, but EPO might be produced in the brain itself, possibly crossing the blood-brain barrier to reach the blood flow. Stereotactical attempts to locate nervous centers of erythropoiesis regulation also failed. EPO secretion obtained by electrical stimulation of different brain areas suggests the existence of widespread secretory cells, which might be the astrocytes. EPO production along the lymph-forming territories and the involvement of the lining macrophages is reported.

A comprehensive methodology for the measurement of stress comprises objective physiological and biochemical methods as well as application of self-reporting scales. This overview focuses on the subjective procedures, their psycho-physiological theoretical background and practical issues. We discuss the most valuable procedures used to assess stress factors, reactions to stress and relationships between the stressed subject and the physical and psychosocial environment. The strengths and limitations of self-reports and the conditions to obtain reliable data and to interpret the findings are outlined. The results of several investigations performed by our teams concern especially the assessment of occupational stress.

We have assessed the antitumoral action of the POLYAS I and POLYAS II vegetal polyphenolic biopreparations--separated and purified from Asclepias syriaca leaves - in rats with various experimental tumoral lines. We studied the therapeutic effect of different doses on the tumor generation process and compared it with the experimental oncostatic action of several standard chemotherapeutic drugs of clinical use (thiotepa, methotrexate, melphalan and cyclophosphamide). In our experimental treatment with the bioactive polyphenolic agents, we have used various doses, both higher and lower than the dose that had conditioned the expression of their antitumoral action upon Guerin T-8 lymphotropic epithelioma and upon Walker 256 carcinosarcoma. We found the antineoplastic effectiveness of those aromatic biopreparations from phytomass to be dose-dependent. We compared the evaluation indices of the antitumoral pharmacodynamic effect we obtained in the treatment with the POLYAS biopreparations with those of reference cytostatic agents. The antitumoral potential of the new natural biopreparations is higher than, equal or close to that of the standard oncochemotherapeutic agents. Antitumoral effectiveness can be improved by an experimental manipulation of the therapeutic doses--which proves the existence of a dose-response relationship. POLYAS I and POLYAS II polyphenolic biopreparations are compatible in point of effectiveness with the standard cytostatic agents, a fact that we considered relevant for the characterization of the POLYAS I and POLYAS II vegetal extracts as potential antineoplastic agents. The quantitative preclinical evaluation of the specific pharmacodynamic effect will be complemented by the investigation of the new polyphenolic biopreparations therapeutic effectiveness in tumors with various degrees of development.

The paper introduces the pre-Hilbert space of standard gene expression (SSGE) based on the normal variability in gene profiles, as revealed by the "spotting" microarray technique. In this space, every point represents a possible gene profile and every continuous curve a possible genetic evolution. The gene "patholog" is defined as the Euclidean distance separating the representative point of the gene profile from the unit, 0-centered hyperball. It is the most general quantification of the alteration in digital genes expression, suitable to define, evaluate, and classify the genetic diseases. Our mathematical model and the afferent computer package allow the researcher to identify the patterns of various genetic afflictions in the SSGE. A publicly available database will be opened where every interested experimentalist could introduce his/her results and process them according to our procedure.

The experiment analysed the evolution of several redox parameters caused by light-dark cycle alteration in different rat brain segments: cortex, brain stem, diencephalon. Continuous light (L:L) enhanced SOD, CAT, GPX and GSH levels to different extents in the various central nervous system regions investigated, depending on the entrainment period: 24 h, 48 h, 72 h, 7 days. Continuous darkness (D:D -24 h, 48 h, 72 h, 7 days) generally diminished SOD, CAT and GSH values, but increased GPX at 48 h and CAT at 72 h. MDA levels were higher in D:D, too. After 7 days L:L or D:D redox indices tended to reach the normal range again. Redox system spatio-temporal versatility and complementarity suggested the existence of a possible biochemical radical cell clock gear.