Experientia最新文献

We used an enhanced luminescence technique to study the response of rat tissues, such as liver, heart, muscle and blood, to oxidative stress and to determine their antioxidant capacity. As previously found for liver homogenate, the intensity of light emission (E) of tissue homogenates and blood samples, stressed with sodium perborate, is dependent on concentration, and the dose-response curves can be described by the equation E = a.C/exp(b.C). The b value depends on the antioxidant defence capability of the tissues. In fact, it increases when homogenates are supplemented with an antioxidant, and is correlated with tissue antioxidant capacity, evaluated by two previously set up methods both using the same luminescence technique. Our results indicate that the order of antioxidant capacity of the tissues is liver > blood > heart > muscle. The a value depends on the systems catalysing the production of radical species. In fact, it is related to the tissue level of hemoproteins, which are known to act as catalysts in radical production from hydroperoxides. The equation proposed to describe the dose-response relation is simple to handle and permits an immediate connection with the two characteristics of the systems analysed which determine their response to the pro-oxidant treatment. However, the equation which best describes the above relation for all the tissues is the following: E = alpha. C/exp(beta.C delta). The parameter delta assumes values smaller than 1, which seem to depend on relative amounts of tissue hemoproteins and antioxidants. The extension of the analysis to mitochondria shows that they respond to oxidative stress in a way analogous to the tissues, and that the adherence of the dose-response curve to the course predicted from the equation E = a.C/exp(b.C) is again dependent on hemoprotein content.

Several Epstein-Barr virus (EBV)-transformed cell lines were used to investigate the pathogenesis of lymphoproliferative diseases and nasopharyngeal carcinoma. The studies focus on the events occurring inside the membrane. On only one occasion, the cell membrane of EBV-transformed B lymphocytes from a cystic fibrosis patient was found to express defective Cl channels (CFTR; Cystic Fibrosis Transmembrane conductance Regulator), as in the airway epithelial cell. No other type of channel in EBV-transformed cells has so far been investigated. In this study, the cell membrane of the B95-8 cell was examined by the patch-clamp technique and compared to the non-EBV-infected BJAB cell. The high conductance (approximately 300 pS) maxi-chloride (Cl) channel activity was the most frequently observed event in inside-out configurations. Under similar experimental conditions, we have found a significantly higher probability of detecting maxi-Cl channel activity on the cell membrane of B95-8 cells (69%) than on BJAB cells (27%), or as previously reported on resting murine B lymphocytes (38%) or intact human T lymphocytes (37%). The relative abundance of the maxi-Cl channel on B95-8 cells may be linked to EBV infection and/or secretory ability.

17 beta-estradiol (E2) and progesterone (P) treatment of immature female rats (10 micrograms/100 g body weight) respectively resulted in 1.38-fold (p < 0.02) and 1.42-fold (p < 0.02) increase in the uterine polyamine oxidase activity, and 2.45-fold (p < 0.001) and 1.43-fold (p < 0.02) increase in the uterine diamine oxidase activity, as compared to the controls. E2 caused a 5-fold (p < 0.05) and a 1.36-fold (p < 0.05) increase in putrescine and spermidine concentration respectively in rat uterus. Increases of 1.7-fold (p < 0.02) and 1.6-fold (p < 0.05) in putrescine and spermine concentration were determined in the P-treated uterus, as compared to the controls. The spermidine/spermine ratio, which is regarded as an index of growth rate, was higher in the E2-treated uterus and lower in the P-treated uterus than in the control uterus. No statistically significant hormonal effects were estimated in the immature liver. The data reported suggest the possibility of an involvement of polyamine-oxidizing enzymes in the modulation of polyamine concentrations in rat uterus by the female sex hormones.

A new method using surface plasmon resonance (SPR) through the BIAcore was used to demonstrate the specific interaction between an anti-CD4 monoclonal antibody (IOT4a), adsorbed on poly(methylidene malonate 2.1.2) (PMM 2.1.2) nanoparticles, and the CD4 molecule. The results obtained were compared with the interaction of the same immunonanoparticles with rabbit anti-mouse Fc antibodies. The molar ratio (Fc)/(Fab) was 1, suggesting that the same number of epitopes on the Fc and the Fab fragments were accessible after IOT4a adsorption onto nanoparticles. Comparing the observed association rates of free antibody and antibody adsorbed on nanoparticles, the number of molecules of IOT4a antibody on PMM 2.1.2 nanoparticles was estimated as between 2.6 and 3 per nanoparticle. The properties of the antibody-coated nanoparticles are compatible with their use as antibody-targeted pharmacophores.

The splenomegaly and the appearance of a significant number of CFU-E (erythroid colony-forming units) and BFU-E1 (erythroid burst-forming units) in the Belgrade laboratory rat (b/b) spleen prompted us to analyse further the molecular evidence for increased hematopoietic proliferation in the b/b spleen. Messenger RNAs (mRNAs) specific for globins, proteins for iron transport and deposition and the band 3 protein were used in rat erythropoietic tissues as markers for proliferation and erythroid differentiation. In the b/b spleen, all mRNAs analysed display an erythroid-specific pattern of expression. This analysis also revealed an enhanced level of mRNA for ferritin in the +/b spleen, whereas erythrocyte-specific mRNA production was normal.

Normal and pathological formation of blood vessels is of considerable interest both in terms of basic scientific processes and clinical applications. Angiogenic events in the adult are likely to represent persistence of developmental mechanisms, and embryos are therefore a suitable experimental model for these processes. Among embryonic tissues, muscle is particularly appropriate for investigation, since it is highly vascularised from early stages. There are a number of competing explanations of how this process is controlled. Bioassays offer advantages over conventional molecular localisation techniques, in that they reveal the presence of active processed forms of the molecules under study, rather than non-processed forms, or non-translated messages. Using these techniques, we report here that embryonic chick muscle, taken from the stages at which blood vessels are forming, produces an angiogenic activity on the chick chorioallantoic membrane (CAM), and transforms NR6 cells in soft agar. Basic fibroblast growth factor (bFGF) is shown to be angiogenic on the CAM in the same way, and also transforms NR6 cells (NR6 cells lack functional epidermal growth factor/transforming growth factor-a receptors, and are believed to respond only to bFGF in this way). Anti-bFGF removes the transforming activity of the embryonic muscle. We conclude that this represents evidence that embryonic chick muscle is producing an FGF-like molecule which is capable of acting as an angiogenic agent at the appropriate times in development.

Forty-one apparently healthy businessmen and -women and an equal number of government workers matched for age and sex underwent serum cholesterol determinations. The mean serum cholesterol levels of businessmen and -women were significantly higher than those of their government worker counterparts (p < 0.001). The marked increase in the serum cholesterol of the business subjects was attributed to their overindulgence and/or eating habits and lack of physical activity. The cardiovascular risk implications of the high cholesterol value and other risk co-factors such as obesity and alcoholism observed among the business subjects are highlighted. We advise that for communities similar to the one described here, public enlightenment programmes about the health benefits of periodic medical assessment and recreational physical activities are necessary. A further comprehensive study of lipid, lipoprotein and other risk factors in these subjects should be encouraged.

Liver fibrosis was induced in rats by simulating human alcoholic eating and drinking patterns. Alcohol addiction was established by gradually increasing the ethanol concentration in the drinking water; salts were added at the terminal stage. The hepatocytes of rats receiving alcohol concentrations exceeding 50% (v/v) (similar to vodka) exhibited alcoholic hyaline (Mallory bodies). Alcoholic liver fibrosis was induced by alternating between regular and autoclaved (vitamin-depleted) diets, simulating the irregular eating habits of human alcoholics. In the livers of rats receiving 70% (v/v) ethanol (comparable to absinthe) with 25% saline and fed the alternating diets, pericellular fibrosis was induced. No significant difference in calorie intake between control and alcohol rats was detected except when rats underwent drinking bouts (heavy drinking phase). This indicates that neither a high-fat diet nor a choline-depleted diet is necessary to induce the alcoholic fibrosis seen in human alcoholics.

Several functions of the gut are locally influenced by peptides and biogenic amines released from enteroendocrine cells. The aim of the present study was to assess whether the luminal stimulus of diet or microbial flora or diet-microbial interactions have an influence on the distribution of enteroendocrine cells along the crypt-surface axes of the small and large intestine. The effects of diet and indigenous flora were investigated by comparing the numbers of argyrophil and serotonin immunoreactive cells in the jejunum and colon of germ free and conventional rats fed either a purified diet containing fine ingredients or a commercial diet containing crude fibre of cereal origin. The effect of human flora were analysed in germ-free rats inoculated with human faecal organisms. 1. Feeding the commercial diet reduced the number of argyrophil endocrine cells in the jejunum and serotonin immunoreactive cells in the colon of germ-free animals but increased the serotonin immunoreactive cells in the colon of conventional animals. 2. The rat flora increased the serotonin immunoreactive cells in the colon of animals fed a commercial diet and decreased in those fed a purified diet. 3. Inoculation of human flora increased the numbers of serotonin immunoreactive cells both in the jejunum and colon. The results provide evidence that the dietary changes and diet-microbial interactions can affect the regional number of enteroendocrine cells.

To study the possible mechanism of the age-dependent involution of the notochord, isolated mesenchyme-free notochords of chick embryos were cultured in vitro and compared with their counterparts in vivo. Two different aspects were evaluated: (1) DNA synthesis measured by [3H]thymidine incorporation and visualized by autoradiography and (2) cell death quantified by counting the number of pyknotic nuclei. The results demonstrate that [3H]thymidine uptake by notochords shows an age-dependent decrease in vitro as well as in vivo. The number of [3H]thymidine-labelled notochord cells, however, is higher in vitro than in vivo. At the same time, there is an age-dependent increase in pyknosis in the notochord in vivo and in vitro. So, during the aging process, the number of both pyknotic nuclei and of [3H]thymidine-labelled nuclei suggest a high turnover of notochord cells in vitro. From these results, we can conclude that the process of involution in aging notochord seems to be controlled by a programmed intrinsic process, which might be influenced partially by the microenvironment in vivo.