Nordic walking increases circulating VEGF more than traditional walking training in postmenopause

OBJECTIVES

Nordic walking (NW) is widely practiced by postmenopausal women. Its effects are peculiar owing to the involvement of more muscle groups than in traditional walking training (WT). Since mechanical load promotes secretion of vascular endothelial growth factor (VEGF) from both skeletal muscle and muscle endothelium, the aim of the study was to compare the effect of NW and WT on VEGF levels.

METHOD

Thirty postmenopausal women were randomly assigned to NW or WT. Both groups trained 40-50 min/day, three times per week, at a mean intensity of 12 on a 15-category scale of the ratings of perceived exertion. Since VEGF is also released from adipocytes, anthropometric parameters were assessed.

RESULTS

NW increased circulating VEGF more than WT (p = 0.041). Furthermore, both study groups exhibited an average decrease in weight (p = 0.023), body mass index (p = 0.024), hip circumference (p = 0.001), and arm fat index, although WT participants had higher values for this index at baseline (p < 0.001) and thus exhibited a greater net decrease compared with the NW participants (p < 0.011).

CONCLUSIONS

These data imply that NW increases the level of circulating VEGF more than does traditional walking when the intensity of training is equivalent.

Vitamin a decreases after a maximal incremental stress test in non-professional male runners with low aerobic performance

The data on the effects of aerobic training on plasma antioxidant vitamins are conflicting. Additionally, most studies focus on the oxidative profiles of professional athletes, but limited information is available for amateur athlete populations. The aim of this study was to evaluate the effects of high-intensity exercise on antioxidant vitamins in non-professional runners with varying levels of aerobic power. Eighty-one male runners underwent an incremental test to exhaustion. The study population was then divided into the following tertiles according to VO2max: Group L (LowVO2max, less than 44.2 mLkg-1min-1), Group M (MediumVO2max, 44.2-49.7 mLkg-1min-1) and Group H (HighVO2max, >49.7). Comparative analyses were performed between Groups L and H. The total antioxidant capacity (TAC), Vitamin (Vit) E, Vitamin A, β-carotene, lycopene and thiobarbituric acid-reactive substances (TBARS) were determined before and 60 min after exercise testing. After the stress test, Vit A decreased and TBARS increased in Group L, whereas no changes in the vitamin concentrations, TAC induction and TBARS reduction were observed in group H. In individuals with low VO2max, an incremental test determined lipid-peroxidation and Vitamin A consumption, whereas H Group increases TAC that buffer TBARS production.

Biological function and clinical relevance of chromogranin A and derived peptides

Chromogranin A (CgA (CHGA)) is the major soluble protein co-stored and co-released with catecholamines and can function as a pro-hormone by giving rise to several bioactive peptides. This review summarizes the physiological functions, the pathogenic implications, and the recent use of these molecules as biomarkers in several pathological conditions. A thorough literature review of the electronic healthcare databases MEDLINE, from January 1985 to September 2013, was conducted to identify articles and studies concerned with CgA and its processing. The search strategies utilized keywords such as chromogranin A, vasostatins 1 and 2, chromofungin, chromacin, pancreastatin, catestatin, WE14, chromostatin, GE25, parastatin, and serpinin and was supplemented by the screening of references from included papers and review articles. A total of 209 English-language, peer-reviewed original articles or reviews were examined. The analysis of the retrospective literature suggested that CgA and its several bioactive fragments exert a broad spectrum of regulatory activities by influencing the endocrine, the cardiovascular, and the immune systems and by affecting the glucose or calcium homeostasis. As some peptides exert similar effects, but others elicit opposite responses, the regulation of the CgA processing is critical to maintain homeostasis, whereas an unbalanced production of peptides that exert opposing effects can have a pathogenic role in several diseases. These clinical implications entail that CgA and its derived peptides are now used as diagnostic and prognostic markers or to monitor the response to pharmacological intervention not only in endocrine tumors, but also in cardiovascular, inflammatory, and neuropsychiatric diseases.

Pathophysiological mechanisms linking depression and atherosclerosis: an overview

It is well recognized that depression is independently associated with cardiovascular events. However, uncertainties remain on the pathophysiological pathways underlying the association between depression and coronary heart disease. In addition to the traditional cardiovascular risk factors, autonomic nervous system (ANS), low grade of inflammation, platelet and hypothalamic-pituitary-adrenal axis function and genetic factors may adversely impact the endothelium of the arterial wall. We provide an overview of the pathophysiological mechanisms and indices which seem to have a role in promoting and accelerating atherosclerosis and its complications due to plaque rupture and thrombosis. Given that the relationship between depression and atherosclerosis cannot be fully explained by single mechanisms, which seem at least partially interrelated, the depression-related dysfunctions in the ANS and hypothalamic-pituitary-adrenal axis seem to play a major role, promoting chronic inflammation, endothelial dysfunction and platelet activation and aggregation, which in turn are key steps in the development of atherosclerosis and its complications.

NAD(P)H oxidase p22(phox) polymorphism and cardiovascular function in amateur runners

AIM

NAD(P)H system represents the major source of superoxide production at cardiovascular (CV) level. It has several genetic variants: in particular, the C242T polymorphism of its p22(phox) subunit is associated with a different oxidase activity, being the T allele related to a lower superoxide production. Although several authors investigated the protective effect of T allele in CV diseases, only few data are available on its functional role in physiological conditions. The aim of our study was to investigate the relationship between the p22(phox) C242T polymorphism and CV function in amateur runners.

METHODS

Seventy-three male amateur runners were screened for CYBA polymorphism. CV analysis was performed by echocardiographic-Doppler examination and by PulsePen tonometer assessment.

RESULTS

The genetic subgroups (CC and CT/TT) did not differ for VM O(2max) and cardiac dimension. Nevertheless, T carriers (n = 40) were characterized by a more efficient myocardial contraction and left ventricular (LV) filling, as evidenced by significant higher values of the midwall fractional shortening, systolic excursion of the tricuspid annular plane and of early/late diastolic wave velocities ratio and by a lower E wave deceleration time. Pulse wave velocity and augmentation index, parameters related to the arterial stiffness, were higher in CC subjects compared with CT/TT also when the analysis was adjusted for weight and diastolic pressure.

CONCLUSION

In amateur runners, CYBA variants may influence both systolic and diastolic function and arterial stiffness. We suppose that the lower oxidative activity that characterizes 242T subjects may positively influence the excitation-contraction and arterial-ventricular coupling mechanisms, thus leading to a more efficient CV function.

Differential impact of acute bout of exercise on redox- and oxidative damage-related profiles between untrained subjects and amateur runners

Despite the demonstrated exercise-induced increase in reactive oxygen species (ROS) production, growing epidemiological evidence indicates that habitual, moderate physical activity reduces the incidence of several oxidative stress-based diseases. This apparent paradox can be explained taking into account that ROS produced during repeated exercise bouts may act as mild stressors able to trigger physiological and biomolecular hormetic responses through a number of redox-sensitive transcription pathways. Unfortunately, much more limited information is available from general population-based research, which could better reflect the condition of common people interested in achieving and maintaining good fitness levels. The present work aimed at investigating whether and how exercise-related habits in non-professional regular runners (n=33) can affect the systemic anti-oxidative capacity, and the resting serum levels of typical lipid peroxidation-related by-products and oxidatively-damaged proteins, in comparison with untrained sedentary individuals (n=25). We also analyzed in both groups the redox response elicited by a modified Bruce-based maximal exercise test on the same parameters. Our findings indicated that long-term regular and moderate practice of aerobic physical activity can increase antioxidant defense systems, lower the resting protein oxidation processes and reduce the immediate up-regulation of lipid-targeting oxidative stress in response to an acute bout of exercise.

NAD(P)H oxidase and pro-inflammatory response during maximal exercise: role of C242T polymorphism of the P22PHOX subunit

Intense exercise induces a pro-inflammatory status through a mechanism involving the NAD(P)H oxidase system. We focused our attention on p22phox, a subunit of the NAD(P)H oxidase, and on its allelic polymorphism C242T, which is known to affect the functional activity of the enzyme. We investigated whether the p22phox C242T variants exhibit systemic effects in healthy subjects by analyzing the proinflammatory and cardiocirculatory responses to physical exercise in endurance athletes. The group of study consisted of 97 long distance runners, 37 +/- 4.4 yrs of age, with similar training history. The subjects underwent a maximal stress test during which both inflammatory and cardiopulmonary parameters were monitored. Our results demonstrate that T allele deeply influences the neutrophil activation in response to intense exercise, since T carriers were characterized by significantly lower release of myeloperoxidase (MPO), a classical leukocyte derived pro-inflammatory cytokine. In addition, the presence of T allele was associated with a higher cardiopulmonary efficiency as evidenced by a significantly lower Heart Rate (HR) at the peak of exercise and, when a dominant model was assumed, by a higher maximal oxygen uptake (VO2 max). On the other hand, no effects of 242T mutation on the plasmatic total antioxidant capacity (TAC) and on the cortisol responses to the physical exercise were detected. In conclusion, our data support a systemic role for p22phox C242T polymorphism that, modifying the intensity of the inflammatory response, can influence the cardiovascular adaptations elicited by aerobic training. These results contribute to support the hypothesis of a systemic effect for the C242T polymorphism and of its possible functional rebound in healthy subjects.

Aerobic performance and antioxidant protection in runners

Reactive oxygen species (ROS) production is known to increase as a result of muscular contractile activity and this phenomenon may perturb the fine-controlled cellular redox homeostasis within cells and tissues. We studied the possible correlations between individual aerobic performance-related factors and the oxidative stress markers profile in the serum of thirty-five endurance male runners that experienced a modified Bruce-based maximal graded exercise test. Our investigation assessed the systemic levels of malondialdehyde (MDA), protein carbonyl content (PCC) and total antioxidant status (TAS). We found that redox-related parameters and aerobic performance indicators were correlated. Indeed, significant negative associations between TAS and PCC (r-value -0.7, p<0.001) and between TAS and total protein content (r-value -0.4, p=0.005) were observed. A significant positive association between total protein and PCC (r-value 0.4, p=0.012) was also revealed. Only a trend of negative correlation between serum total protein and anaerobic threshold (r-value -0.3, p=0.07) was found. Interestingly, different responses in MDA levels were elicited by the ergometric test as a function of the individual anaerobic threshold. High aerobic capacities may be promising anthropometric factors indicative of adapted biochemical environments featuring enhanced protection against the oxidative challenge elicited by both regular endurance training and single intense exercise bouts.

Novel shift of Jak/Stat signalling characterizes the protective effect of aurintricarboxylic acid (ATA) from tumor necrosis factor-alpha toxicity in human B lymphocytes

Previous results demonstrated that the occurrence of death in human peripheral B lymphocytes by TNF-alpha was paralleled by the activation of the cytoplasmic Jak1 and Tyk2 protein kinases, along with the recruitment of transcription factors Stat3 and Stat5b. In this study we demonstrate that the balance of survival signals in the presence of TNF-alpha was altered by the addition of a salicylate compound, the endonuclease inhibitor aurintricarboxylic acid (ATA). Apoptosis effected by TNF-alpha alone was suppressed by ATA and this event was paralleled by phosphorylation and nuclear translocation of Jak2, Stat2, Stat4 and NF-kB, along with inhibition of caspase activation. These results confirm that among the different cellular responses evoked by TNF-alpha in human B cells, recruitment of Jak/Stat proteins and possible related gene modulation represent contributing factors and address the issue of the development of potential therapeutic strategies aimed at the control of systemic or local effects produced by TNF-alpha.

Circulating hematopoietic progenitor cells in a fetus with alpha thalassemia: comparison with the cells circulating in normal and non-thalassemic anemia fetuses and implications for in utero transplantations

Our aim was to evaluate the number of progenitor cells circulating in an alpha-thalassemic fetus during its infusion in utero with paternal CD34(+) and adult red cells and to compare those values with those circulating in normal and non-thalassemic anemic fetuses of matched gestational age. The treatment of the alpha-thalassemic fetus has been described elsewhere. Fetal blood was obtained from normal and anemic fetuses by fetal blood sampling for diagnostic or therapeutic purposes according to a protocol approved by the human subject committee. The number of progenitor cells in fetal blood was estimated on the basis of the number of colonies they gave rise to in semisolid cultures. The alpha-thalassemic fetus, as did the other fetuses analyzed, contained high numbers (10(6)-10(7) depending on the age) of progenitor cells, values which were higher than the number (10(4)-10(5)) of paternal progenitor cells being transplanted. Progenitor cells with adult characteristics (adult kinetics of differentiation) were detected rapidly (10 min) after the CD34(+) cell infusion, but were not detectable 2-3 weeks after the transplant. These results indicate that adult progenitor cells do not have a numerical advantage when transplanted into alpha-thalassemic fetuses.

Histochemical and biochemical analysis of phospholipase C isoforms in normal human gastric mucosa cells

The expression and activity of PIP2-specific phospholipase C (PLC) in healthy human gastric mucosa cells were investigated by means of Western blotting, immunohistochemistry and in vitro activity assays. The results provide direct evidence for an almost exclusive expression of the PLC beta family and at the same time supply a cellular cartography of each represented isoform of this family. In this context, the putative roles of each isoform in the signaling events regulating the gastric mucosa metabolic machinery are discussed. These data provide a unique map of the specific expression and cellular distribution of the most represented PLC isoforms in healthy human gastric mucosa cells, which may constitute a reference point in future studies aimed at highlighting possible cytochemical and biochemical hallmarks of metaplastic or malignant transformation.

Differential effects of stromal derived factor-1 alpha (SDF-1 alpha) on early and late stages of human megakaryocytic development

Stromal derived factor-1 alpha (SDF-1 alpha), the high-affinity ligand of CXC-chemokine receptor 4 (CXCR4), was added to human CD34(+) hematopoietic progenitor cells that can be induced to differentiate along the monocytic or megakaryocytic lineages. In control liquid cell cultures supplemented with two different cytokine cocktails: stem cell factor (SCF), interleukin-3 (IL-3), macrophage-colony stimulating factor (M-CSF), and 10% fetal calf serum (FCS), or, SCF and thrombopoietin (TPO), the expression of surface CXCR4 progressively increased in both the CD14(+) monocytic and CD41(+) megakaryocytic lineages. While SDF-1 alpha caused only modest effects on cells of the monocytic lineage, it induced profound down-regulation of CXCR4 in megakaryocytic cells at all stages of differentiation. Moreover, while SDF-1 alpha initially up-regulated the early megakaryocytic antigen CD41, at later time points (days 12-16) it induced down-regulation of the late megakaryocytic antigen CD42b. Consistently, at day 16, the number of mature megakaryocytes was significantly decreased in cultures supplemented with SDF-1 alpha. These findings indicate that, besides its primary role in regulating the retention of precursor cells in hematopoietic tissues, the SDF-1 alpha/CXCR4 system participates in the regulation of megakaryocytic development by stimulating the formation of immature megakaryoblasts and inhibiting the formation of mature megakaryocytes.

Morphological features of apoptosis in hematopoietic cells belonging to the T-lymphoid and myeloid lineages

Taking into account that apoptosis plays a pivotal role in shaping normal hematopoiesis, morphological features of apoptosis were investigated in both primary cells and continuous cell lines committed towards the T-lymphoid and the myeloid lineages. Apoptosis was induced using: dexamethasone (10(-7) M) for primary rat thymocytes; infection with the T-lymphotropic human herpesvirus 7 (HHV-7) for peripheral blood CD4+ T-cells; staurosporine (1 microM) for MOLT4 CD4+ lymphoblastoid T-cells, HL60 human promyelocytic and U937 human monoblastoid cells; and using senescence of the culture for primary human megakaryocytes. Cell morphology was examined by both transmission electron microscopy and in situ nick translation (NT) revealed by laser scanning confocal microscopy. In spite of the use of different apoptotic agonists, the morphological aspects of apoptosis were similar within the T-lymphoid and the myeloid lineage. While chromatin condensation characterized the early apoptotic events in both lineages, late apoptoses were mainly characterized by further nuclear condensation in lymphoid cells and by production of micronuclei in myeloid cells. Moreover, NT analysis clearly showed that the micronuclei derived from HL60 undergoing apoptosis were composed of both degraded and intact DNA. Thus, T-lymphocytes and myeloid cells showed a lineage-related behavior characterizing the late morphological aspects of apoptosis.

Functional independence and interdependence of the Src homology domains of phospholipase C-gamma1 in B-cell receptor signal transduction

B-cell receptor (BCR)-induced activation of phospholipase C-gamma1 (PLCgamma1) and PLCgamma2 is crucial for B-cell function. While several signaling molecules have been implicated in PLCgamma activation, the mechanism coupling PLCgamma to the BCR remains undefined. The role of PLCgamma1 SH2 and SH3 domains at different steps of BCR-induced PLCgamma1 activation was examined by reconstitution in a PLCgamma-negative B-cell line. PLCgamma1 membrane translocation required a functional SH2 N-terminal [SH2(N)] domain, was decreased by mutation of the SH3 domain, but was unaffected by mutation of the SH2(C) domain. Tyrosine phosphorylation did not require the SH2(C) or SH3 domains but depended exclusively on a functional SH2(N) domain, which mediated the association of PLCgamma1 with the adapter protein, BLNK. Forcing PLCgamma1 to the membrane via a myristoylation signal did not bypass the SH2(N) domain requirement for phosphorylation, indicating that the phosphorylation mediated by this domain is not due to membrane anchoring alone. Mutation of the SH2(N) or the SH2(C) domain abrogated BCR-stimulated phosphoinositide hydrolysis and signaling events, while mutation of the SH3 domain partially decreased signaling. PLCgamma1 SH domains, therefore, have interrelated but distinct roles in BCR-induced PLCgamma1 activation.

Inefficient phospholipase C activation and reduced Lck expression characterize the signaling defect of umbilical cord T lymphocytes

Adult and neonatal immunocompetent cells exhibit important functional distinctions, including differences in cytokine production and susceptibility to tolerance induction. We have investigated the molecular features that characterize the immune response of cord blood-derived T lymphocytes compared with that of adult T lymphocytes. Our findings demonstrate that phospholipase C (PLC) isozymes, which play a pivotal role in the control of protein kinase C activation and Ca2+ mobilization, are differently expressed in cord and adult T lymphocytes. PLCbeta1 and delta1 are expressed at higher levels in cord T cells, while PLCbeta2 and gamma1 expression is higher in adult T lymphocytes. PLCdelta2 and gamma2 appear to be equally expressed in both cell types. In addition, a functional defect in PLC activation via CD3 ligation or pervanadate treatment, stimuli that activate tyrosine kinases, was observed in cord blood T cells, whereas treatment with aluminum tetrafluoride (AlF4-), a G protein activator, demonstrated a similar degree of PLC activation in cord and adult T cells. The impaired PLC activation of cord blood-derived T cells was associated with a a very low expression of the Src kinase, Lck, along with a reduced level of ZAP70. No mitogenic response to CD3 ligation was observed in cord T cells. However, no signaling defect was apparent downstream of PLC activation, as demonstrated by the mitogenic response of cord T cells to the pharmacologic activation of protein kinase C and Ca2+ by treatment with PMA and ionomycin. Thus, neonatal cord blood-derived T cells show a signaling immaturity associated with inadequate PLCgamma activation and decreased Lck expression.

Immunocytochemical localization of phospholipase C isozymes in cord blood and adult T-lymphocytes

The response of T-cells to peptide antigen plus major histocompatibility complex (MHC) consists of a series of cellular events collectively called T-cell activation. An essential component of this pathway is phospholipase C (PLC)gamma1, whose hydrolytic activity increases rapidly after binding of ligands to the T-cell receptor (TCR) and consequent activation of tyrosine kinases. Recent studies also suggest a GTP binding protein-dependent activation of PLCbeta during the early steps of T-cell activation. On the basis of these findings, we first checked the expression of PLC isoforms by Western blotting and by confocal and electron microscopy techniques, and then we looked for the phosphoinositide breakdown induced by CD3 engagement in cord and adult T-lymphocytes. Our results indicated that PLCbeta1 was almost exclusively expressed in cord T-cells, whereas PLCbeta2 was more strongly represented in the adult. The amount of PLCgamma1 was found to be larger in the adult than in cord cells. No significant differences were found in PLCgamma2 and delta2 expression. PLCdelta1 was scarcely detectable. On CD3 stimulation, adult lymphocytes gave rise, as expected, to a dramatic increase in phosphoinositide breakdown, whereas in cord cells this response was scarcely detected. These results indicate that a shift in PLC expression occurs in the postnatal period and that this change is associated with induction of the capability to respond to CD3 engagement with phosphoinositide hydrolysis.

Apoptotic pathways depend on the target enzymatic activity and not on the triggering agent

Molt-4 human leukemia cells were triggered to apoptosis by various agents with different mechanisms of action. Staurosporine, a protein kinase C (PKC) inhibitor; camptothecin, a topoisomerase I blocking drug; and tiazofurin, an inhibitor of inosine 5'-phosphate dehydrogenase (IMPDH), were used. Ultrastructural analysis showed morphologic changes characteristic of apoptosis that were very similar for all three agents. Nevertheless, DNA oligonucleosomic fragmentation was not detectable by agarose gel electrophoresis. However, a genomic DNA cleavage appeared after pulse-field gel electrophoresis (PFGE) in cells treated with these agents for 24 h. Furthermore, in situ nick translation (NT) showed a finely spotted nuclear labelling in staurosporine-treated cells and a compact fluorescence after camptothecin incubation. In tiazofurin-treated cells an intermediate pattern was found. Therefore, apoptotic agents with different mechanisms of action induced the formation of large genomic DNA fragments and very similar ultrastructural changes. Therefore, both phenomena and the closely related apoptosis progression depend on target cell machinery and not on the triggering agent.

Different approaches to the study of apoptosis

The morphological features of cell undergoing programmed cell death is well known and has been widely described in a number of experimental models with a variety of apoptotic triggering agents. Despite the similar cell behaviour, underlying molecular events seem variable and only partially understood. A multiple approach appears crucial to better clarify the phenomenon. The first technique, DNA gel electrophoresis, allows the identification of fragmented DNA and has been long considered the hallmark of apoptosis. Different patterns of DNA cleavage, which can be identified by conventional or "pulsed-field gel" electrophoresis, are presented and discussed. "In situ" labelling methods are also described both with terminal deoxynucleotidyl transferase and DNA polymerase I, aimed at the study of the distribution of DNA cleavage areas. Flow cytometry is also proposed and different technical approaches, based on different laser utilizations, are discussed. Ultrastructural analysis, allowing the study of apoptotic cell details, is finally considered.

Novel evidence of expression and activity of ecto-phospholipase C gamma1 in human T lymphocytes

Although much is known about the intracellular phospholipase C (PLC) specific for inositol phospholipids, few data are available about the presence of a less common PLC at the external side of the membrane bilayer of some cell types. This ectoenzyme seems to play particular roles in cellular function by hydrolyzing inositol lipids located on the outer leaflet of the plasma membrane. Here, we provide the first evidence that peripheral T lymphocytes express a discrete level of a PLCgamma1 at the outer leaflet of the plasma membrane. Flow cytometry showed that the PLCgamma1-positive (PLCgamma1(+)) cells (approximately 37%) were CD8(+) and CD45RA+. Biochemical evidence indicated that (1) this ectoenzyme displays a mass similar to the cytoplasmic form, (2) it is phosphorylated on tyrosine residues, and (3) its activity is Ca2+-dependent. In addition, this enzyme appeared to be correlated with the proliferative state of the cell, since stimulation with phytohemagglutinin (PHA) downregulated both its expression and activity, which were restored by treatment with an antiproliferative agent like natural interferon beta. Moreover, the different kinetics of formation of its hydrolytic products, inositol 1 phosphate and inositol 1:2 cyclic phosphate (Ins(1)P and Ins(1:2 cycl)P), formed upon incubation of the lymphocytes with [3H]-lyso-phosphatidylinositol (PI), allow the hypothesis of a selective involvement of the two inositol phosphates in the mechanisms regulating the metabolism of particular T-lymphocyte subsets.

Engagement of DNA polymerases during apoptosis

DNA replicative and repair machinery was investigated by means of different techniques, including in vitro nuclear enzymatic assays, immunoelectron microscopy and confocal microscopy, in apoptotic cell lines such as HL-60 treated with methotrexate, P815 and K562 exposed to low temperatures and Friend cells exposed to ionizing radiation. The results showed a shift of DNA polymerase alpha and beta activities. DNA polymerase alpha, which in controls was found to be the principal replicative enzyme driving DNA synthesis, underwent, upon apoptosis, a large decrease of its activity being replaced by DNA polymerase beta which is believed to be associated with DNA repair. Such a modulation was concomitant with a topographical redistribution of both DNA polymerase alpha and the incorporation of BrdUrd throughout the nucleus. Taken together, these results indicate the occurrence of a dramatic response of the DNA machinery, through a possible common or at least similar behaviour when different cell lines are triggered to apoptosis. Although this possibility requires further investigation, these findings suggest an extreme attempt of the cell undergoing apoptosis to preserve its nuclear environment by switching on a repair/defence mechanism during fragmentation and chromatin margination.

Detection of apoptosis in peripheral blood cells of 31 subjects affected by Down syndrome before and after zinc therapy

Thirty-one patients affected by Down syndrome (DS) were investigated to study the presence of apoptosis in peripheral blood cells in relation to the plasma levels of zinc. Twelve patients had undergone therapy with ZnSO4, while the remaining 19 were untreated. The presence of programmed cell death was evaluated by means of electron microscopy, in situ nick translation (NT), and agarose gel electrophoresis of DNA. These approaches evidenced the presence of apoptosis in peripheral blood cells of patients before therapy with ZnSO4, while after zinc supplementation there was a reduction in the number of apoptotic cells. These results suggest that the process of programmed cell death in peripheral blood cells of patients with Down syndrome is related to the plasma levels of zinc ion.

Phospholipase C gamma 1 overexpression and activation induced by interferon beta in human T lymphocytes: an ISGF3-independent response

Interferons exert their antiviral, antiproliferative and immunoregulatory activities by stimulating the expression of several genes. Such genes disclose a common element within their promoters, defined Interferon Stimulated Response Element (ISRE), which binds a nuclear factor(s) translocated from the cytoplasm to the nucleus (ISGF3) after the binding of interferon (IFN) to the specific receptor. Here we report the induction of the synthesis and of the hydrolytic activity of phospholipase C gamma 1 (PLC gamma 1) in human T lymphocytes by IFN-beta. The increased level of PLC gamma 1 becomes evident after 90 min of IFN-beta treatment and is still detectable after 24 h. Neither the PLC gamma 1 overexpression induced by IFN nor the increased hydrolytic activity of the enzyme appear to be affected by pretreatment of the cells with the protein tyrosine kinase inhibitor genistein, which is known to prevent the association of ISGF3 components. These results suggest that in human T lymphocytes IFN-beta can activate other transcription factor(s) distinct from ISGF3 to regulate PLC gamma 1 expression. In addition, the ability of this enzyme to hydrolyse PIP2, also in the presence of genistein, implies the possibility that this enzyme can exert its hydrolytic activity independently of protein tyrosine kinase activation.

Engagement of DNA polymerases during apoptosis

DNA replicative and repair machinery was investigated by means of different techniques, including in vitro nuclear enzymatic assays, immunoelectron microscopy and confocal microscopy, in apoptotic cell lines such as HL-60 treated with methotrexate, P815 and K562 exposed to low temperatures and Friend cells exposed to ionizing radiation. The results showed a shift of DNA polymerase alpha and beta activities. DNA polymerase alpha, which in controls was found to be the principal replicative enzyme driving DNA synthesis, underwent, upon apoptosis, a large decrease of its activity being replaced by DNA polymerase beta which is believed to be associated with DNA repair. Such a modulation was concomitant with a topographical redistribution of both DNA polymerase alpha and the incorporation of BrdUrd throughout the nucleus. Taken together, these results indicate the occurrence of a dramatic response of the DNA machinery, through a possible common or at least similar behaviour when different cell lines are triggered to apoptosis. Although this possibility requires further investigation, these findings suggest an extreme attempt of the cell undergoing apoptosis to preserve its nuclear environment by switching on a repair/defence mechanism during fragmentation and chromatin margination.

Shift of DNA polymerase alpha nuclear distribution and activity in apoptotic human leukaemia cells

The changes in the distribution of DNA polymerase alpha in nuclei from HL-60 cells treated with Methotrexate (MTX) for up to 15 hr. were checked by means of both confocal analysis and electron microscopy analysis. The results provided evidence that, relative to controls, in the MTX treated cells the enzyme undergoes a topographical rearrangement throughout the nucleus, showing a pattern of distribution which calls to mind the nuclear matrix structure. The "in vitro" analysis of DNA polymerases alpha, beta, and gamma activities revealed that, in nuclei from control cells, DNA polymerase alpha was the principal DNA polymerase driving this "in vitro" system, while after 15 hr. of MTX treatment its activity was largely decreased and replaced by DNA polymerase beta, which is believed to be associated with DNA repair. Taken together, these results suggest that among the intracellular processes elicited by MTX-induced apoptosis in HL60 cells, the redistribution of DNA polymerase alpha and the stimulation of DNA polymerase beta activity might represent an extreme attempt of the cell to preserve the replicative machinery during fragmentation and chromatin margination.

Interferon beta mediated intracellular signalling traffic in human lymphocytes

The early molecular mechanisms activated by the treatment of human lymphocytes with human interferon beta have been studied. These identify an early increase with respect to control, in diacylglycerol (DG) levels as response to interferon treatment. Such a DG production was derived from the rapid and sequential activation of phosphoinositide specific phospholipase C and phospholipase D pathway. This suggests that a synergistic involvement of phosphatidylinositol-bis-phosphate (PIP2) hydrolysis and phosphatidylcholine (PC) breakdown provide early molecular events upon the interaction between interferon beta and its cell surface receptors. This finally leads to the slowing down of cell growth.

Rapid and transient phosphorylation of nuclear matrix proteins upon interferon-alpha treatment in Daudi lymphoma cells

Evidence for a rapid and transient hyperphosphorylation of a 45 kD protein in isolated nuclei from interferon-alpha-treated Daudi lymphoma cells is presented. Extraction of nuclear matrices from these nuclei has provided further evidence for the association of such a protein in the nuclear matrix structure. Because phosphorylation assays performed directly on nuclear matrices from interferon-treated cells have revealed rapid and transient increase of gamma 32P-ATP incorporation into this 45 kD band, an early involvement of the nuclear matrix in the response of the nucleus to the interferon antiproliferative message is suggested.

Phosphoinositidase C beta 1 isoform expression is modulated by interferon alpha in Burkitt lymphoma cells

The expression of phosphoinositidase C (PIC) at nuclear and cytoplasmic level has been revealed in control and interferon treated Burkitt lymphoma cells by means of western blotting and immunocytochemical analysis employing specific monoclonal antibodies against beta 1, gamma 1 and delta 1 isozymes. Results have indicated that PIC isoform beta 1, mainly detectable in the nucleus, undergoes transient modifications early after interferon treatment. PIC delta 1 has been found only at cytoplasmic level, apparently insensitive to interferon treatment, while PIC gamma 1 was scarcely or not detected either in the cytoplasmic or in the nuclear compartment. These results suggest that interferon may exert its antiproliferative effect activating at least two distinct pathways of signal transduction, at cytoplasmic and nuclear level, involving inositol lipid cycle mainly in the nucleus by modulation of PIC beta 1 expression.

Nuclear phosphoinositide signalling enzyme in human B lymphoid cells

The modulation of phosphoinositidase C (PIC) beta activity upon interferon treatment in Burkitt lymphoma cells (Daudi) and its localization and expression have been analyzed by Western blotting, immunocytochemical and immunoelectronmicroscopy analysis. Results have disclosed an early increase of phosphatidyl-inositol-bisphosphate (PIP2) hydrolysis at nuclear level upon interferon (IFN) treatment paralleled by the evidence of an increase of PIC beta 1 expression. PIC beta 1 expression has been detected in the nuclear compartment also in a clone of Daudi cells selected for the resistance to the antiproliferative action of interferon alpha but no modulation of the enzyme has been detected upon interferon treatment. Since no changes in terms of PIP2 hydrolysis have been found at nuclear level in this selected line, we suggest that the antiproliferative action of interferon on Burkitt lymphoma cells is mediated by a possible recruitment of nuclear PIC beta 1 expression.

Interferon mediated phosphatidylinositol uptake and processing in nuclei isolated from Burkitt lymphoma cells

The kinetic analysis of exogenous [3H]phosphatidylinositol (PI) uptake and processing by nuclei isolated from Daudi lymphoma cells upon interferon alpha treatment has been performed. Results have disclosed that, with respect to controls, interferon induces an evident stimulation of label incorporation into nuclei. The incorporated [3H] PI has been found for phosphorylation and hydrolytic cleavage, indicating that the intranuclear transduction system activated by interferon at plasma membrane level, might involve the PI cycle as a possible route of intracellular signalling.