Romanian journal of physiology : physiological sciences最新文献

This invited review briefly outlines the importance of membrane water permeability, highlights the landmarks leading to the discovery of water channels. After a decade of systematic studies on water channels in human RBC Benga's group discovered in 1985 the presence and location of the water channel protein among the polypeptides migrating in the region of 35-60 kDa on the electrophoretogram of RBC membrane proteins. The work was extended and reviewed in several articles. In 1988, Agre and coworkers isolated a new protein from the RBC membrane, nick-named CHIP28 (channel-forming integral membrane protein of 28 kDa). However, in addition to the 28 kDa component, this protein had a 35-60 kDa glycosylated component, the one detected by the Benga's group. Only in 1992 Agre's group suggested that "it is likely that CHIP28 is a functional unit of membrane water channels". Half of the 2003 Nobel Prize in Chemistry was awarded to Peter Agre (Johns Hopkins University, Baltimore, USA) "for the discovery of water channels", actually the first water channel protein from the human red blood cell (RBC) membrane, known today as aquaporin 1 (AQP1). The seminal contributions from 1986 of the Benga's group were grossly overlooked by Peter Agre and by the Nobel Prize Committee. Thousands of science-related professionals from hundreds of academic and research units, as well as participants in several international scientific events, have signed as supporters of Benga; his priority is also mentioned in several comments on the 2003 Nobel Prize.

Deuterium depleted-water (DDW) is a new available tool for decreasing deuterium concentration in the environment of cells in culture. Several types of established cell lines, both normal and neoplastic were grown in culture media dissolved with DDW and compared with the same strains, in the same amounts, grown in media dissolved with normal distilled water. Naive mice splenocytes were grown, under stimulation with proliferation triggers, like bacterial lipopolysaccharide (LPS) and Concanavalin A (ConA) in the same conditions. The growth and proliferation were estimated using the MTT assay. Both established cell types and explanted splenocytes in the DDW-media had a significantly higher growth rate than cell cultured in normal media. In an attempt to identify the membrane mechanisms involved in the growth stimulation by DDW, the membrane proton transporters Na+/H+ antiporter and H+/K+ATP-ase were inhibited with their selective blockers amiloride and respectively lansoprazole. The results, however incomplete, point towards a lack of involvement of the Na+/H+ antiporter and a possible implication of the H+/K+ATP-ase.

We used cDNA microarrays to examine the extent to which the expression of individual genes varies in mouse brain and in cultured N2A neuroblastoma cells mRNA extracted from sixC57B1/6J neonatal mouse brains and from four distinct cultures of N2A neuroblastoma cells was cross-hybridized with ten AECOM cDNA microarray chips to determine the individual gene expression variability. A mathematical algorithm reduced the effect of potential sources of variability not associated to the biological material by about 80%. The interval estimates of the standard deviation of individual gene expressionwere determined through chi-square statistics. The newly introduced relative expression variability, defined as the quotient of the middle of the interval estimate of the standard deviation and the mean expression ratio (and its inverse, gene transcription control), was used to rank the most unstably and the most stably transcribed genes. In brains of different animals and in separate cultures of N2A cells, unique sets ofgenes exhibited exceptional stability or were highly variable. Possible implications for such tight or loose transcriptional control are discussed.

The phagocytic function was proved to be a periodic, circadian process. Its acrophase appears to be differently timed in species with different activity type, occurring in the evening in diurnal species and at night in nocturnal ones. The main pineal hormone melatonin, whose secretion occurs strictly at dark, has been shown to play a role in the control of inflammation and to exert a certain stimulatory effect upon phagocytosis in vitro. The aim of the present study was to assess whether the phagocytic activity of neutrophils in the blood of rats exhibits a circadian rhythmicity similar to that of other nocturnal rodents (mice) and also if a constant light regimen alters its amplitude and/or chronostructure. Wistar rats were submitted to either an artificial light-dark 12/12 regimen (LD) or to constant light (LL), for 15 days. In vitro phagocytosis of the neutrophils in whole blood against E.coli was assessed at 10:00, 16:00, 22:00, and 04:00 hours. In LD, phagocytosis appears to be a rhythmical function, with statistically significant differences between the highest value at 04:00 hrs and the lowest at 10:00 hrs. Constant light induces a 30% depression of the phagocytic ability throughout the whole 24 hours cycle, without altering its oscillations. The darkness period appears to play the role of a synchronizer; in its absence the rhythm tends to free-run. It may be stated that rhythmical melatonin secretion is responsible only for maintenance of the phagocytic level, probably via the anterior hypothalamic area and thymus, while it cannot account directly for the nocturnal increase of phagocytosis.

The basic, fundamental property of living structures is excitability. This process defines how an organism responds to both internal and external stimuli. Previous studies have indicated the existence of physical and chemical interactions between cations and anions sites of proteins within the extracellular environment that have a specific functional importance. However, it is not well understood whether specific cations may alter the function of specific proteins. We report here the results of studies that indicate interaction of specific cations such as sodium may alter the physico-chemical action of heparin. The importance of these interactions is discussed.

Biomedical engineering (BME) includes clinical engineering and bioengineering. Bioengineering is academically oriented towards theory and research in biology using the methods of exact sciences such as maths and physics, while clinical engineering (CE) has a rather practical orientation focusing on the general management of clinic/hospital equipment and providing aid to the medical staff in the use of advanced technologies for diagnosis and therapy purposes. The Romanian physiological community has been closely involved in the growth of BME that has now come of age in this country. Radu Vrâncianu's great intuition in opening the door to this science and its practical application in an institution created by Daniel Danielopolu definitely represented a good chance for Romanian public health. Recently, both clinical engineering and medical bioengineering have been introduced into the Romanian Classification of Occupations.

A good amount of experimental data suggests the existence of a circadian control of the inflammatory process. It was shown that migration of neutrophils in chemotactic gradient, ingestion of particles, vascular permeability etc. are rhythmical circadian functions. Melatonin, the pineal hormone secreted during the darkness phase, has been shown to be involved in the control of inflammation. The present study aims to assess whether neutrophil adherence to nylon fibers exhibits circadian rhythmicity and also if its amplitude and/or chronostructure are altered in a constant light regimen. Wistar rats were submitted to either an artificial light-darkness 12/12 regimen (LD) or to constant light (LL), for 15 days. Adherence of the neutrophils in whole blood was assessed at 10:00, 16:00, 22:00, and 04:00 hrs. In LD. neutrophil adherence appears to be a rhythmic, biphasic function, with the acrophase at 10:00, a secondary peak at 22:00 and trough values in the late dark hours. Constant light induces a depression of the adherence ability by about 10%, except for the 04:00 hrs point, where the value in LL is higher than in LD. The fact that adherence and phagocytic activity do not oscillate in phase suggests that the physiological relevance of neutrophil adherence goes beyond that of a first stage of the phagocytic process.

We have used a highly quantifiable cDNA microarray method to determine the stabilities and expression levels within gene families involved in cell-cell and cell-matrix interactions in neonatal mouse brain and heart. In addition, we have characterized the extent to which deletion of the gap junction protein connexin43 (Cx43) affects these characteristics. Our observations for individual genes revealed a range of differences and variabilities in transcription level among family members; calculation of the genomic patholog (a global measure of gene expression alteration) indicates that these cell interaction genes contribute disproportionately to the overall phenotype. We found significant transcriptomic differences between brain and heart, that deletion of Cx43 considerably decreased gene expression variability and that the average contribution to the pathology of the genes whose encoded proteins are involved in cell-cell or cell-matrix interaction in the Cx43-null mice was about twenty times higher than that of other genes. These findings indicate that gap junction gene expression influences the expression of other genes involved in intercellular and cell-substrate interaction and that expression of these genes is under strong regulatory pressure in the Cx43-null mouse, presumably representing a compensatory response to Cx43 deletion.

The research activity upon erythropoiesis regulation carried out by the team in the Physiology Department and in the Institute of Medical Research of the Romanian Academy in Cluj-Napoca developed continuously after 1950. Our studies contributed to the isolation, identification and characterization of erythropoietin (Epo) and also to a better understanding of the nervous adaptation mechanisms to hypoxia. At present, it is well known that hypoxia acts upon erythropoiesis through Epo production. Direct central nervous stimulation through hypoxia induces, via a neuro-humoral mechanism, a sympatho-adrenal response and release of Epo. Adaptive polyglobulia as a response to hypoxia increases the capacity of oxygen binding and transport. In this paper we attempted to identify the role of the sympathetic nervous system in adaptation to hypoxia correlated with Epo secretion. Experiments were carried out in three groups of rats, respectively, with cervical, thoracic, and lumbar (without celiac) sympathectomy. The sympathectomized animals were submitted to hypobaric or to hemorrhagic hypoxia, in parallel with control groups. Erythrocytic parameters (red blood cells, reticulocytes, hematocrit, and haemoglobin) were repeatedly assayed during the following 2-4 weeks. The results showed that animals with cervical sympathectomy adapt in a deficient manner to hypoxia; lacking the adaptive sino-carotid reflexes, adaptation occurs through increased Epo secretion, animals with cervical sympathectomy having higher counts of reticulocytes and of red blood cells at the end of experiment than intact animals. Thoracic sympathectomy has little influence upon the erythrocytic response, as the largest part of the respiratory and circulatory sympathetic reactions occur via the cervical sympathetic nerve. Lumbar sympathectomy without removal of the celiac ganglion does not decrease the erythrocytic response as expected; on the contrary, the erythrocytic response is increased as compared to controls.

Beginning with 1975, our group has performed some studies using an erythropoietin (EPO ) extract prepared according to an original technique from sera of anemic rabbits. Our results have contributed to the understanding of the glycoproteinic nature of this extract as well as of some of its biological features. These results were confirmed only after 1985, when recombinant EPO was obtained. The aim of this study is to emphasize some of our priorities, controversial at that time. We have shown the radioprotective effect of an EPO extract, in correlation with red cell proliferation and with an increased rate of nucleic acid metabolism and bone marrow blood flow. Consequently, we proposed the investigation of the bone marrow function using EPO. Our results are correlated with recent data obtained with recombinant EPO. They refer to the ability of EPO to prevent apoptosis, its antioxidant effects, and its ability to modulate the sympathoadrenal response to hypoxia.