Purinergic regulation of glucose and glutamine synthesis in isolated rabbit kidney-cortex tubules

The effects of extracellular purinergic agonists and their breakdown products on glucose and glutamine synthesis in rabbit kidney-cortex tubules incubated with aspartate + glycerol or alanine + glycerol + octanoate were investigated. A rapid extracellular degradation of ATP was accompanied by an accumulation of AMP, inosine, and hypoxanthine. Extracellular ATP and its breakdown products accelerated glucose synthesis in renal tubules, while ammonium released from adenine-containing compounds enhanced glutamine synthesis and diminished the degree of gluconeogenesis stimulation. In contrast to AMP and inosine, ATP evoked calcium signals, while both ATP and inosine decreased intracellular cAMP content and accelerated the flux through fructose-1,6-bisphosphatase as concluded from changes in gluconeogenic intermediates. Since (i) the activity of partially purified renal fructose-1,6-bisphosphatase was increased upon protein phosphatase-1 treatment and decreased following treatment of previously dephosphorylated enzyme with protein kinase A catalytic subunit and (ii) both 8-bromoadenosine 3',5'-cyclic monophosphate and 8-(4-chlorophenyltio)-cAMP inhibited renal glucose synthesis, it seems likely that in rabbit renal tubules ATP and inosine stimulate gluconeogenesis via cAMP decrease, which favors the appearance of a more active, dephosphorylated form of fructose-1,6-bisphosphatase, a key gluconeogenic enzyme.     

Changes in the cellular behaviour of human colonic cell line Caco-2 in response to butyrate treatment

Gut-derived adenocarcinoma Caco-2 cells were treated with sodium butyrate (NaB) at physiologically relevant concentrations. We characterized its effects on proliferation, differentiation, apoptosis, adhesion to the solid support and interleukin-8 secretion. Differentiation was determined by brush border alkaline phosphatase activity. Apoptosis was assessed by acridine orange and Hoechst stains. Differentiation and apoptosis were analyzed in both adherent and floating cell populations. The transformed Caco-2 cells did not retain their malignant phenotype in the presence of NaB. They appeared to undergo a change in the phenotype induced by NaB, as indicated by reduced proliferation, enhanced differentiation, stimulation of apoptosis leading to decreased viability of cells, and stimulation of interleukin-8 secretion. Considering all the above facts and data, we postulate that Caco-2 cells cultured in NaB supplemented medium could regain the phenotypic characteristics of the phenotype of the parent cell from which originated the Caco-2 line.     

Molecular basis of inherited predispositions for tumors

On the basis of literature data and own experience the authors review the current knowledge about the molecular basis of inherited predispositions for tumors. They hypothesize that in the near perspective 5-10 years studies using existing registry data/material and the latest novel technology will allow the identification of the molecular background for the majority of hereditary cancers which will have enormous practical consequences especially for the prevention of malignancies.     

Evolutionary consequences of asymmetric dispersal rates

We study the consequences of asymmetric dispersal rates (e.g., due to wind or current) for adaptive evolution in a system of two habitat patches. Asymmetric dispersal rates can lead to overcrowding of the "downstream" habitat, resulting in a source-sink population structure in the absence of intrinsic quality differences between habitats or can even cause an intrinsically better habitat to function as a sink. Source-sink population structure due to asymmetric dispersal rates has similar consequences for adaptive evolution as a source-sink structure due to habitat quality differences: natural selection tends to be biased toward the source habitat. We demonstrate this for two models of adaptive evolution: invasion of a rare allele that improves fitness in one habitat but reduces it in the other and antagonistic selection on a quantitative trait determined by five additive loci. If a habitat can sustain a population without immigration, the conditions for adaptation to that habitat are most favorable if there is little or no immigration from the other habitat; the influence of emigration depends on the magnitude of the allelic effects involved and other parameters. If, however, the population is initially unable to persist in a given habitat without immigration, our model predicts that the population will be most likely to adapt to that habitat if the dispersal rates in both directions are high. Our results highlight the general message that the effect of gene flow upon local adaptation should depend profoundly on the demographic context of selection.     

Uterine blood supply as a main factor involved in the regulation of the estrous cycle--a new theory

The paper presents a new theory on the physiological mechanism of initiation of luteolysis, function of endometrial cells and protection of corpus luteum. This theory is based on previous studies published by the authors and their coworkers on the retrograde transfer of PGF2alpha in the uterine broad ligament vasculature during the estrous cycle, early pregnancy and pseudopregnancy. The studies were focused on cyclic changes in uterine blood supply and the apoptosis of endometrial cells. Moreover, the results of many other authors are cited. The statements of the theory are as follows: 1. The initiation of luteolysis is a consequence of regressive changes in the endometrium which are due to the reduction of the uterine blood supply below the level necessary to provide for the extended needs of active endometrium. 2. During the luteal phase, both a considerable increase in uterine weight and a decrease in blood flow through the uterine artery, resulting from increasing progesterone concentration, reduce the uterine blood supply. In comparison to the volume of blood flowing to the porcine uterus during the estrus period, only 30-40% of the blood volume is determined on day 12 of the estrous cycle. The uterine weight at that time is 40-60% larger than that in the early luteal phase. Thus, due to the considerable constriction of uterine blood vessels, there is a discrepancy between the requirement for oxygen and other factors transported by blood and the possibility of supplying the uterus with these substances. After reaching the threshold of uterine blood supply level, which in pigs takes place around day 12 of the estrous cycle, regressive changes and PGF2alpha release from endometrial cells occurs. 3. Estrogens and progesterone are the major factors affecting blood flow in vessels supplying the uterus. The factors that modulate, complement and support vasodilation and vasoconstriction are: PGE2, LH, oxytocin, cytokines, neurotransmitters and other local blood flow regulators. In some animal species these modulators, especially those of embryonic origin, may be crucial for the status of uterine vasculature. 4. During early pregnancy, the action of embryo signals (estrogens, cytokines), endometrial PGE2 as well as LH results in the relaxation of the uterine artery (pigs: day 12) and, consequently, in an increase in uterine blood supply. This reaction of the maternal recognition of pregnancy effectively prevents regressive changes in well developed endometrial cells to occur. 5. Local uptake and retrograde transfer of PGF2alpha into the uterine lumen during early pregnancy protects corpus luteum from PGF2alpha luteolytic action. 6. During the period of regressive changes resulting from the limited uterine blood supply, endometrial cells restrain PGF2alpha synthesis. They are, however, still capable of releasing prostaglandin when uterine blood supply is improved after the embryo appears in the uterus. This potential capability for PGF2alpha synthesis was demonstrated in in vitro studies when endometrial cells collected during its regressive phase were incubated in medium and stimulated by LH and oxytocin. 7. Prostaglandin F2alpha pulses in venous blood flowing from the uterus do not confirm pulsatile secretion of PGF2alpha. The pulses may result from the pulsatile excretion of PGF2alpha with venous blood according to the rhythmic uterine contractions associated with oxytocin secretion. 8. The results supporting this concept are presented and discussed in due course. The critique of Bazer and Thatcher's theory on exocrine versus endocrine secretion of prostaglandin F2alpha during the estrous cycle is also depicted.     

A simple test for detection of linkage

The paper presents a proposition for detection of linkage of genes responsible for metrical traits. Taking into account the expected means for early generations (F(1), F(2), F(3)) and a population of homozygous lines (in this case doubled haploid lines, DH derived from a cross between two homozygous parents) as well as estimators of genetic parameters m, [d], [i], [h] and [l], the expected values for these parameters in the presence of linkage have been formulated. It was found that when there is no linkage, the expression F(1) - 6F(2) + 8F(3) - 3DH(mean) is equal to zero. Thus, an experiment covering DH lines and F(1), F(2), F(3) hybrids makes it possible to obtain, beside information of interest, also information on presence or absence of linkage.     

Cellular and cytokine immunoregulation in patients with chronic obstructive pulmonary disease and bronchial asthma

BACKGROUND: Different forms of chronic airway inflammation may involve diverse pathogenic elements. In general, deficient defence response is a feature of chronic obstructive pulmonary disease (COPD), whereas distorted immunoregulatory mechanisms lead to development of asthmatic symptoms. In addition to diverse effector mechanisms, the cellular and humoral elements participating in the development of immune response may appear to be different in COPD and bronchial asthma (BA) patients. AIMS: To evaluate the immunoregulatory properties of T cells and monocytes in cultures of peripheral blood mononuclear cells (PBMC) and to determine the chosen cytokine profiles in COPD and BA patients. METHODS: The microcultures of PBMC from COPD and BA patients were assessed for the T-cell response to mitogens, saturation of interleukin (IL)-2 receptors, T-cell suppressive activity and monokine influence on lymphocyte proliferation. Concomitantly, the cytokine (IL-1beta, interleukin-1 receptor antagonist, tumour necrosis factor-alpha, IL-4, IL-6, IL-8) concentrations were determined in the serum, the broncho-alveolar lavage fluid and in the culture supernatants. RESULTS: The T-lymphocyte reactions (response to phytohaemagglutinin, IL-2 receptor saturation, suppressive activity) were lower in BA patients than in COPD patients. Reversely, the immunogenic activity of monocytes (IL-1beta versus IL-1ra production) was higher in BA patients than in COPD patients. The highest values of cytokine concentrations were found in the culture supernatants. The concentrations of tumour necrosis factor-alpha, IL-4, IL-6 and IL-8 were significantly higher and the concentration of IL-1ra was lower in BA patients than in COPD patients. CONCLUSION: The assessments of cellular immunoregulatory properties and cytokine profiles in the cultures of blood mononuclear cells may prove helpful for diagnostic and therapeutic discrimination between BA and COPD patients.     

Assessment of RAPD markers for barley doubled haploid lines resistant and susceptible to Fusarium culmorum at seedling and adult plant growth stages

Thirty doubled haploid (DH) lines of barley derived from F(1) of a cross between the six-rowed cultivar Pomo and two-rowed cultivar Maresi were examined for susceptibility to Fusarium seedling blight (SB) and head blight (FHB), measured by mycotoxin (nivalenol) content of kernels. RAPD (random amplified polymorphic DNA) polymorphism was analysed by using 53 decamer primers. Amplification products (APs) were 200 bp up to 2000 bp in size on average 5.7 per primer and the total number of APs was 284, 51.06% of which were polymorphic. Only 32 APs differentiated the examined DH lines - 19 APs for nivalenol content of kernels and 13 for seedling resistance. DH lines segregated with continuous distribution of resistance to FHB and SB. At the seedling stage all DH lines exhibited lower susceptibility than parental cultivars, but in the adult stage only two lines (MP 2 and MP 7) appeared to be more resistant to FHB, i.e. accumulated in kernels a lower amount of mycotoxin than cultivars Maresi and Pomo.     

Intraspecies variability of Desulfovibrio desulfuricans strains determined by the genetic profiles

Fifteen (soil and intestinal) strains of Desulfovibrio desulfuricans species were typed by PCR method with the use of primers specific for repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) sequences. As a result, characteristic DNA fingerprints for the strains were obtained. Moreover, the genetic profiles were found to be useful for typing and distinguishing the strains of D. desulfuricans. According to cluster analysis, PCR with primers complementary to the sequences REP appeared to be slightly more discriminatory than PCR with ERIC primers for the investigated strains. Distinct fingerprint patterns of two isolates derived from the same patient pointed to the different origin of both strains.     

Uncoupling protein-2 prevents neuronal death and diminishes brain dysfunction after stroke and brain trauma

Whereas uncoupling protein 1 (UCP-1) is clearly involved in thermogenesis, the role of UCP-2 is less clear. Using hybridization, cloning techniques and cDNA array analysis to identify inducible neuroprotective genes, we found that neuronal survival correlates with increased expression of Ucp2. In mice overexpressing human UCP-2, brain damage was diminished after experimental stroke and traumatic brain injury, and neurological recovery was enhanced. In cultured cortical neurons, UCP-2 reduced cell death and inhibited caspase-3 activation induced by oxygen and glucose deprivation. Mild mitochondrial uncoupling by 2,4-dinitrophenol (DNP) reduced neuronal death, and UCP-2 activity was enhanced by palmitic acid in isolated mitochondria. Also in isolated mitochondria, UCP-2 shifted the release of reactive oxygen species from the mitochondrial matrix to the extramitochondrial space. We propose that UCP-2 is an inducible protein that is neuroprotective by activating cellular redox signaling or by inducing mild mitochondrial uncoupling that prevents the release of apoptogenic proteins.