Onset of exercise and diet program in obese women: metabolic and anorexigenic responses related to weight loss and physical capacities

Perturbations of energy balance induce compensatory processes that may alter expected weight loss. In obese patients, our aim was to investigate the relationships that occurred between fasting plasma concentrations of anorexigenic peptides and metabolic parameters, appetite, physical capacity, and weight loss in the 5 first days of a program associating exercise and caloric reduction. Thirteen obese women were monitored from day 1 to day 5 with 2 exercise sessions in day 2 and day 4. We measured, in a fasted state, changes in body weight, hunger ratings, and plasma concentrations of fatty acids, triglycerides, leptin, insulin, amylin, peptide YY, and insulin-resistance index. Physical performance was assessed by a 6-min walking test. The program resulted in significantly reduced body weight (0.75±0.4 kg; p=0.001), of plasma concentrations of triglycerides, insulin, amylin, peptide YY, and the insulin-resistance index, and also increased fatty acids (p<0.05). Hunger ratings were increased (p<0.05). Program-induced changes in fatty acids, leptin, and insulin concentrations were related to physical performance (r(2)=0.45, 0.59, and 0.52; p<0.05, respectively) and to weight loss (r(2)=0.65, 0.57, 0.55; p<0.05, respectively). Five days of diet and exercise induced weight loss, improved lipid profile, and decreased insulin resistance while hunger ratings increased. Subjects with higher physical capacity lost more weight, presented higher increases in fatty acids and lower changes of leptin and insulin concentrations suggesting a better metabolic flexibility. To reduce the compensatory responses that can occur with energy imbalances, our study supports to account for individual activity level before prescribing weight-loss program associating diet and exercise.

Metallothionein as a clonable tag for protein localization by electron microscopy of cells

A benign, clonable tag for the localization of proteins by electron microscopy of cells would be valuable, especially if it provided labelling with high signal-to-noise ratio and good spatial resolution. Here we explore the use of metallothionein as such a localization marker. We have achieved good success with desmin labelled in vitro and with a component of the yeast spindle pole body labelled in cells. Heavy metals added after fixation and embedding or during the process of freeze-substitution fixation provide readily visible signals with no concern that the heavy atoms are affecting the behaviour of the protein in its physiological environment. However, our methods did not work with protein components of the nuclear pore complex, suggesting that this approach is not yet universally applicable. We provide a full description of our optimal labelling conditions and other conditions tried, hoping that our work will allow others to label their own proteins of interest and/or improve on the methods we have defined.

Hierarchical clustering of immunohistochemical analysis of the activated ErbB/PI3K/Akt/NF-kappaB signalling pathway and prognostic significance in prostate cancer

Background:

The PI3K/Akt signalling pathway, induced by epidermal growth factor receptor (EGFR) and Her-2, is involved in the constitutive activation of NF-κB in prostate cancer cell lines. In this study, we extended the in vitro observation using an ex vivo model of prostate cancer tissues and assessed the prognostic significance of the PI3K/Ak/NF-κB signalling determinants.

Methods:

We analysed a prostate cancer tissue microarray of 63 patients for the expression of total and activated EGFR, Her-2 receptors and the signalling molecules PTEN, phospho-PTEN, Akt, phospho-Akt and the NF-κB subunit p65. Data were analysed using Spearman's rho test, Kaplan–Meier curves and multivariate Cox regression analysis. In addition, a non-supervised hierarchical clustering analysis was applied to stratify patients according to prognostic groups in terms of risk of recurrence.

Results:

The concomitant overexpression of activated EGFR and Her-2 was correlated with the nuclear expression of NF-κB. EGFR, phospho-EGFR, phospho-Her-2, ErbB3 and nuclear NF-κB were associated with the overall biochemical recurrence (BCR) of patients. The non-supervised hierarchical clustering analysis resulted in the separation of patients into five groups according to BCR.

Conclusions:

These results validate the previous in vitro data on ErbB involvement in NF-κB activation and shows evidence for a significant role of ErbB/PI3K/Akt/NF-κB signalling in the progression of prostate cancer.

High KI67 expression is associated, in a multi-variate model, with lower risk of biochemical recurrence in prostate cancer patients following radical prostatectomy

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Background: The prediction of disease progression in prostate cancer patients following radical prostatectomy (RP) remains problematic. The use of molecular markers could offer a better stratification of patients more at risk of progression. As such, we recently reported that nuclear ErbB3 was associated with Gleason score and hormone-refractory status. The objective of this study was to evaluate whether ErbB3 could predict overall biochemical recurrence (BCR). In addition, we evaluated if three nuclear markers known to be associated with progression (Cyclin D1, Ki67 and androgen receptor) were more significant predictors of BCR than ErbB3 alone or in combination. Methods: Using immunohistochemistry, we analyzed a tissue microarray containing 373 cores from 63 RP specimens. No patient had received hormone therapy prior to surgery and prior to BCR. The quantitative analysis of nuclear staining was measured by two independent observers (ErbB3, Cyclin D1 and AR) or with the ImagePro Plus softwareTM (Ki67). Marker expressions were categorized as either positive or negative according to the median expression. Results: Of the four markers analyzed, Ki67 alone was the strongest predictor of overall BCR. In a multi-variate Cox regression model (backward conditional), while controlling for the pre-operative PSA, Gleason score and lymph node invasion at time of surgery, KI67 was found to be an independent predictor of BCR with a KI67+ patients having lower risk of BCR (HR=-2.51, p=0.015, CI 95%: 1.19–5.29). We then analyzed if different marker combinations could predict BCR. Patients positive for nuclear AR or AR+/Cyclin D1+ double positive were found to have lower risk of BCR (Kaplan-Meier, p=0.047 and p=0.026, respectively). However, in the multi- variate model, the combinations of Cyclin D1+/AR+ (HR=-2.28, p=0.053, CI 95%: 0.94–5.49), ErbB3+/Ki67+ (HR=-2.43, p=0.034, CI 95%: 1.07- 5.52) and AR+/Ki67+ (HR=-2.32, p=0.049, CI 95%: 1.01–5.35) could not improve on the predictive value of KI67 alone. Conclusions: The major new finding of the study is that patients positive for KI67 expression were at a lower risk of developing BCR, which contrast previously published results, and warrants further investigations.

No significant financial relationships to disclose.

Gamma-Secretase, ErbB4 nuclear localization and neuregulin expression correlates with prostate cancer patient clinical outcome

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Background: Membrane protein ErbB4 is a member of ErbB growth factor receptor family, which can be activated by neuregulins (NRG). Upon neuregulin activation, ErbB4 is cleaved within its transmembrane domain by presenilin γ-secratase (PSN) to release an intracellular domain that translocates into the nucleus. Although, ErbB4 ligand-dependant translocation of ErbB4 to the nucleus and its nuclear activity has been reported in breast cancer cell lines, there are few reports concerning ErbB4 nuclear localization and its clinical relevance. Here, we report for the first time the clinical relevance of ErbB4 nuclear localization, NRG, and PSN expression in prostate cancer tissues. Methods: Immunostaining using anti-ErbB4, anti-PSN2 and anti-neuregulin antibodies was done on a set of tissue microarrays (TMA) from 140 patients. The TMAs contained, 92 cores of normal prostate tissue obtained from 46 autopsy specimens from young males, 373 tumor and normal adjacent cores from 63 hormone sensitive PCa (HSPCa) patients, and 146 cores from 31 hormone refractory PCa (HRPCa) patients. Results: We found a statistically significant increase (p<0.01) in the percentage of ErbB4 nuclear localization (68.7% vs 53.2%), NRG expression (2.06 vs 1.41) and PSN2 expression (2.14 vs 1.53) when comparing cancerous tissues to normal tissue adjacent to cancer. Interestingly, a similar statistically significant increase in nuclear ErbB4 and NRG expression was observed when comparing HRPCa to HSPCa (p<0.001). In cancerous tissues, a strong correlation was found between nuclear ErbB4 and NRG expression (r=0.672), between nuclear ErbB4 and PSN2 expression (r=0.51), and between PSN2 and NRG expression (r=0.71). Nuclear ErbB4 and PSN2 inversely correlated with tumor stage and lymph node invasion. Kaplan Meier analysis of nuclear ErbB4 (p=0.030) and PSN2 expression (p=0.018) showed an inverse association with biochemical recurrence (BCR) of PCa. In multivariate analyses including these three markers and clinical parameters, only nuclear ErbB4 retained an independent prognosis value. Conclusion: Our results suggest that high nuclear ErbB4 along with increased PSN2 expression have a protective effect against prostate cancer progression and BCR.

No significant financial relationships to disclose.

ErbB3, Cyclin D1 and Ki67 nuclear staining predicts biochemical recurrence in prostate cancer treated by radical prostatectomy

10096

Background: The nuclear accumulation of growth factor receptor was reported to be associated to increased cell proliferation. Cyclin D1 and Ki67 are nuclear markers of cell proliferation. Deregulation of Cyclin D1 and Ki67 expression play a role in tumorigenesis and metastasis. Recently, we observed that nuclear localization of ErbB3 was associated with prostate cancer progression. The objective of this study was to determine if the association of cell proliferation markers and nuclear localization of ErbB3 could predict biochemical recurrence (BCR) in patients with prostate cancer following radical prostatectomy. Methods: Using immunohistochemistry we analyzed a tissue microarray containing 386 cores from 64 formalin-fixed paraffin embedded specimens from prostate cancer patients who had undergone radical prostatectomy. No patient had received hormone therapy prior to surgery and prior to BCR. Antibodies against Cyclin D1, ErbB3 and Ki67 proteins were used. Results: Nuclear staining was 60%, 67% and 86% for Cyclin D1, ErbB3 and Ki67 respectively. In our cohort, 29 of 64 PCa patients (45%) had a BCR after a median 3 years of follow-up. Thirty seven (37) percent of patients had positive nuclear staining for all three markers. BCR free survival probability at 3 years was not significant for each marker individually, except for ErbB3 in positive surgical margin patients. When all three markers were combined for nuclear staining Kaplan-Meier analysis BCR free was 0.4 and 0.1 for positive and negative nuclear staining respectively (p=0.0068). Univariate COX regression analysis shows a 2.98 fold (95% CI: 1.29 - 6.86, p=0.01) higher rate of BCR in patients positive for these three markers. In addition, in a multivariate model, including pre-operative PSA (p=0.19), pathologic stage (p=0.29), Gleason grade (p=0.40) and specimens that had positive nuclear staining for the 3 markers were associated with a 3.97 fold higher rate of BCR (95% CI: 1.54 - 10.25, p=0.0068). Conclusion: These results suggest that the association of cell proliferation markers and nuclear localization of ErbB3 could be useful in predicting recurrence following radical prostatectomy and guide therapeutic decisions. Large scale trials are needed to confirm these results.

No significant financial relationships to disclose.

A ligand-independent androgen receptor function protects from inositol hexakisphosphate-induced cell death

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Background: The androgen receptor (AR) is often aberrantly expressed or activated in hormone-refractory (HR) prostate cancer (PCa). Though it is not clear whether this is directly linked to AR expression, various cell survival pathways are over-activated in HR-PCa, which is characterized by its poor clinical outcome and resistance to available therapies. Inositol hexakisphosphate (IP6) is a phytochemical anti-cancer agent, which we have found to be more effective in PCa cell lines that do not express the AR. Our goal was to address the mechanism of IP6-induced cell death and to evaluate if and how the AR may interfere with its activity. Methods: We used LNCaP, DU145, 22Rv1 as well as wild-type PC3 and AR-expressing PC3 (PC3AR) cell lines to assess the metabolic toxicity of IP6 by WST-1 assay in normal, androgen-supplemented, and androgen-depleted cell culture conditions. A siRNA targeting the androgen receptor (AR) was used to control for genuine AR-mediated effects in the PC3/PC3AR cell lines. Apoptosis was quantified using fluorogenic caspase-3 assays as well as quantitative DNA fragmentation assays. Expression of a variety of genes involved in apoptosis and cell survival pathways was evaluated by real time PCR. Results: While the activity of IP6 was not modulated by the presence of androgens for any cell line, PC3AR cells were significantly more resistant to IP6 than wild-type PC3 cells according to WST-1, caspase-3 and DNA fragmentation assays (p < 0.05). Down-regulation of the AR in the PC3AR cell line resulted in increased metabolic toxicity of IP6 on these cells (p < 10−5). Although treatment with IP6 resulted in the up-regulation of the pro-apoptotic genes Puma, Noxa, as well as of IRF-2 and IkB-αλπηα in PC3 cells, this did not occur in PC3AR cells (p < 0.05). Conclusion: We conclude that, at least in PC3/PC3AR, cells IP6 sensitivity is linked to a ligand-independent function of the AR. To our knowledge, this is the first report of a ligand-independent AR function involved in resistance to a cytotoxic compound. Establishing the molecular details of this novel function is a major part of our ongoing research.

No significant financial relationships to disclose.

Expression and localisation of Akt-1, Akt-2 and Akt-3 correlate with clinical outcome of prostate cancer patients

We investigated the correlation between the expression and localisation of Akt-1, Akt-2, Akt-3, phospho-Akt proteins and the clinicopathological parameters in 63 prostate cancer specimens. More than 60% of cancerous tissues overexpressed Akt-1, Akt-2 or Akt-3. Cytoplasmic Akt-1 expression was correlated with a higher risk of postoperative prostate-specific antigen (PSA) recurrence and shorter PSA recurrence interval. Cytoplasmic Akt-2 did not show any significant correlation with clinicopathological parameters predicting outcomes. Cytoplasmic Akt-3 was associated with hormone-refractory disease progression and extracapsular invasion. Nuclear Akt-1 and Akt-2 expression were correlated with favourable outcome parameters such as absence of lymph node and perineural invasion. Kaplan–Meier analysis and Cox regression model also showed that Akt-1 and Akt-2, but not Akt-3 or phospho-Akt was associated with a significantly higher risk of PSA recurrence. In contrast, nuclear Akt-1 was significantly associated with a lower risk of PSA recurrence. Multivariate analysis revealed that clinical stage, Gleason score and the combined cytoplasmic nuclear Akt-1 marker in cancerous tissues were significant independent prognostic factors of PSA recurrence. This is the first report demonstrating in patients with prostate cancer and the particular role of Akt-1 isoform expression as a prognostic marker depending of its localisation.

Gene expression profiling of primary cultures of ovarian epithelial cells identifies novel molecular classifiers of ovarian cancer

In order to elucidate the biological variance between normal ovarian surface epithelial (NOSE) and epithelial ovarian cancer (EOC) cells, and to build a molecular classifier to discover new markers distinguishing these cells, we analysed gene expression patterns of 65 primary cultures of these tissues by oligonucleotide microarray. Unsupervised clustering highlights three subgroups of tumours: low malignant potential tumours, invasive solid tumours and tumour cells derived from ascites. We selected 18 genes with expression profiles that enable the distinction of NOSE from these three groups of EOC with 92% accuracy. Validation using an independent published data set derived from tissues or primary cultures confirmed a high accuracy (87–96%). The distinctive expression pattern of a subset of genes was validated by quantitative reverse transcription–PCR. An ovarian-specific tissue array representing tissues from NOSE and EOC samples of various subtypes and grades was used to further assess the protein expression patterns of two differentially expressed genes (Msln and BMP-2) by immunohistochemistry. This study highlights the relevance of using primary cultures of epithelial ovarian cells as a model system for gene profiling studies and demonstrates that the statistical analysis of gene expression profiling is a useful approach for selecting novel molecular tumour markers.

Coronary and aortic vasoreactivity protection with endothelin receptor antagonist, bosentan, after ischemia and hypoxia in aged rats

This study investigated the effects of bosentan, a dual endothelin ET(A) and ET(B) receptor antagonist, during hypoxia-reoxygenation of senescent aorta and during ischemia-reperfusion of senescent heart. Isolated aortic rings and isolated hearts from adult and senescent rats were submitted, respectively, to hypoxia/reoxygenation (20/30 min) and to low-flow ischemia/reperfusion (45/30 min), without or with bosentan (10(-5) M). In the aorta, bosentan treatment prevented the impairment of relaxation in response to acetylcholine after hypoxia-reoxygenation at both ages. In the heart, coronary flow recovery during reperfusion, which is lower in senescents than in adults (48% vs. 76% of baseline value, respectively; P<0.05) was fully prevented by bosentan. Prevention of endothelial dysfunction during reoxygenation of hypoxic aorta and of coronary vasoconstriction during reperfusion of ischemic heart with a dual endothelin ET(A) and ET(B) receptor antagonist suggests a role of endothelin in the vulnerability of aorta to hypoxia-reoxygenation, and of coronary arteries to ischemia-reperfusion, especially during aging.

Disruption of NF-kappa B signaling and chemokine gene activation by retroviral mediated expression of IKK gamma/NEMO mutants

Phosphorylation of I kappa Bs--the cytoplasmic inhibitors of the NF-kappa B transcription factors--is the key event which triggers activation of the NF-kappa B cascade. Signal-mediated phosphorylation of I kappa B alpha is mediated by a multiprotein complex, the I kappa B kinase (IKK) complex, which is composed of at least three identified subunits. Two of these polypeptides, IKK alpha and IKK beta, also known as IKK1 and IKK2, are the catalytic subunits of the kinase complex and phosphorylate I kappa B alpha and I kappa B beta. The third component, NEMO/IKK gamma, does not exhibit kinase activity, but rather constitutes a regulatory subunit. In the present study, C-terminal truncated forms of IKK gamma--Delta C-IKK gamma 306 and Delta C-IKK gamma 261--were stably expressed in the myeloid cell line U937 by retroviral-mediated gene transfer. Overexpression of Delta C-IKK gamma resulted in a reduction in IKK kinase activity in vitro, a subsequent decrease in NF-kappa B DNA binding activity, and inhibition of chemokine gene induction in response to TNFalpha stimulation or paramyxovirus infection. This study demonstrates the efficacy of Delta C-IKK gamma as a repressor of IKK signaling and NF-kappa B activation and suggests a potential gene therapy approach to limit chronic inflammation due to chemokine hyperactivation.

Interferon activation and innate immunity

The interferons are a family of cytokine mediators critically involved in alerting the cellular immune system to viral infection of host cells. Interferons not only exhibit important antiviral effects but also exert a key influence on the quality of the cellular immune responses and amplify antigen presentation to specific T cells. Type I interferon (IFN-alpha and IFN-beta) is secreted by virus-infected cells while type II, immune or gamma interferon (IFN-gamma) is mainly secreted by T cells, natural killer (NK) cells and macrophages. Interferons interact with specific cellular receptors, which promote production of second messengers ultimately leading to expression of antiviral and immune modulatory genes. The IFN genes themselves are regulated by transcriptional and posttranscriptional mechanisms including modulation by a family of interferon regulatory factors (IRFs) synthesised by host cells. IFNs activate macrophages, induce B cells to switch immunoglobulin type, alter T helper response, inhibit cell growth, promote apoptosis and induce an antiviral state in uninfected cells. The therapeutic potential of the IFNs is currently the focus of intense attention in a number of virus-associated diseases, tumours and autoimmune disorders.

Benznidazole, a drug employed in the treatment of Chagas' disease, down-regulates the synthesis of nitrite and cytokines by murine stimulated macrophages

Benznidazole (BZL) is a nitroheterocyclic drug employed in the chemotherapy of Chagas' disease, a protozoan disease caused by Trypanosoma cruzi. Because this parasite mostly replicates in macrophages, we investigated whether BZL was likely to modify the synthesis of macrophage mediators such as nitrite, tumour necrosis factor-alpha (TNF-alpha), IL-1beta, IL-6 and IL-10. Control and stimulated murine macrophages (lipopolysaccharide (LPS) and/or interferon-gamma (IFN-gamma)) were treated with BZL and measurements were carried out in culture supernatants collected 24 h later. Synthesis of nitrite, IL-6 and IL-10 was maximal upon combined stimulation with LPS + IFN-gamma, whereas lower amounts of the three mediators were detected when both stimuli were given alone. BZL treatment significantly reduced nitrite, IL-6 and IL-10 production, to undetectable levels in some cases, particularly IL-6 and IL-10. LPS was the most potent stimulus of IL-1beta and TNF-alpha production, followed by LPS + IFN-gamma and IFN-gamma in decreasing order. BZL partly inhibited TNF-alpha synthesis, but this effect was smaller than that observed for nitrite, IL-6 and IL-10. LPS-induced production of IL-1beta was also affected by BZL. Semiquantification of gene expression for inducible nitric oxide synthase (iNOS) showed that BZL completely inhibited iNOS gene induction by IFN-gamma, and resulted in respective inhibitions of 30% and 50% with LPS- and LPS + IFN-gamma-stimulated cells. BZL was not cytotoxic on macrophage cultures, as shown by the lactate dehydrogenase activity. Besides its trypanocidal activity, BZL may also alter the balance between pro- and anti-inflammatory mediators with important consequences for the course of T. cruzi infection.

Effects of anabolic/androgenic steroids on regenerating skeletal muscles in the rat

We have examined the effect of male sexual hormones on the regeneration of skeletal muscles. Degeneration/regeneration of the left soleus and extensor digitorum longus muscles (EDL) of Wistar male rats was induced by an injection of snake venom (2 microg, Notechis scutatus scutatus). During the muscle regeneration (25 days), rats were treated with either oil (CON), nandrolone (NAN), NAN combined with exercise (NAN + EXE) or were castrated (CAS). Muscle growth and myosin heavy chain (MyHC) isoform content of regenerating muscles were studied. Castration altered the concentrations of MyHC in venom-treated EDL (P < 0.01) and soleus (P < 0.05). NAN increased the mass (P < 0.01) of regenerating soleus and decreased the relative amount of fast MyHC protein (% of total, P < 0.05). The effect of NAN + EXE on the fast MyHC proteins of venom-treated soleus was opposite (P < 0.05). NAN and NAN + EXE were without effect on the regenerating EDL (P > 0.05). In conclusion, it is possible that male sexual hormones play a role in the growth (synthesis of contractile proteins) of regenerating muscles in rat. In addition, contrary to NAN + EXE, NAN could be beneficial to soleus regeneration.

Inhibitors of ADP-ribosylation impair inducible nitric oxide synthase gene transcription through inhibition of NF kappa B activation

In murine macrophages, inducible NO synthase II (iNOS or NOS-II) is induced at the transcriptional level by IFN-gamma, alone or synergistically with LPS. We investigated the possible role of reactions of ADP-ribosylation in triggering the signaling pathways involved in NOS-II gene expression. Stimulation with IFN-gamma and/or LPS of RAW 264.7 macrophages, transiently transfected with the NOS-II promoter, was inhibited by ADP-ribosylation inhibitors, indicating that they interfered with the signal(s) responsible for NOS-II gene transcription. We therefore explored the effect of these inhibitors on the activity of IRF-1 and NF kappa B transcription factors known to be involved in NOS-II induction by IFN-gamma and LPS. No effect was observed on IRF-1 activation. However, NF kappa B binding to its target sequence diminished and transfection experiments with an NF kappa B-driven reporter plasmid demonstrating that ADP-ribosylation inhibitors suppressed NF kappa B-dependent promoter activity. These results provide evidence that a step involving ADP-ribosylation is required to activate NF kappa B-mediated gene transcription.

Effects of inhibitors of ADP-ribosylation on macrophage activation

Nitric oxide (NO) is a potent mediator involved in many biological functions including macrophage cytotoxicity and non-specific immunity against parasites, bacteria and viruses. Murine macrophages possess the capacity to express the inducible NO synthase (iNOS) which is not constitutively expressed but induced at the transcriptional level by interferon gamma (IFN-gamma) alone or synergistically with LPS. We have investigated the possible role of ADP-ribosylation reactions in the signaling pathway involved in NO synthase induction, since ADP-ribosylation has been reported to be involved in the expression of certain IFN-gamma and LPS-inducible genes. We found that inhibitors of ADP-ribosylation inhibited nitrite synthesis in RAW 264.7 macrophages after stimulation by IFN-gamma and LPS. These ADP-ribosylation inhibitors acted by preventing NO synthase mRNA induction, without inhibiting NO synthase enzyme activity. IRF-1, a transcription factor induced and activated by IFN-gamma was recently shown to be involved in iNOS induction. We showed that inhibitors of ADP-ribosylation had no effect on IFN-gamma-mediated mRNA induction of IRF-1 nor on its activation and binding to its target sequence in the iNOS gene. In addition, the inhibitors failed to impair the IFN-gamma-mediated antiviral activity against VSV virus. Since induction by IFN-gamma of IRF-1 and induction of the antiviral state proceed through the JAK/STAT signalling pathway, our results imply that ADP-ribosylation reactions are not involved in triggering this pathway. Although the precise mechanism requires further investigation, our results indicate that ADP-ribosylation is a crucial step restricted to the signalling pathway which leads to iNOS mRNA induction, as well as TNF and MHC class II induction during macrophage activation.

Effect of increased physical activity on growth and differentiation of regenerating rat soleus muscle

Our purpose was to determine the effect of physical exercise on growth and differentiation during regeneration of a slow-twitch muscle. Degeneration/regeneration of the left soleus muscles of Wistar female rats was induced by injection of a snake venom. Muscular differentiation was studied by monitoring the sequential expression of the various myosin heavy chain isoforms (MHCs). Rats were assigned to one of two groups: cage sedentary (n = 14) or exercised (n = 16). The exercise programme began 1-day post-injection and the rats ran 1 h/day on a motorized treadmill. Then, 9 and 25 days after venom treatment, the soleus MHC phenotype as determined by immunohistology, electrophoresis and immunoblotting, was studied. At 25 days the expression of MHCs by regenerating soleus was not changed by the increased level of physical activity (P > 0.05). Exercised and sedentary regenerating muscles contained similar numbers of type-I fibres (100% of total fibres), levels of MHC-1 (85.4 and 89.5% of total MHCs), MHC-2a and M/HC-2x/d and their fibres expressed MHC-1 (100% of total fibres) and MHC-2 (45-50%) in the same way. Moreover, the masses of regenerating and nonregenerating soleus were significantly increased by physical exercise (P < 0.02). At 9 days no effect of muscular exercise was found. In conclusion, endurance exercise did not alter differentiation of regenerating soleus. Moreover regenerating soleus can respond to increased physical activity by enhancing its mass in the same way as mature muscle.

Differential expression of inducible NO synthase in two murine macrophage cell lines

Although primary macrophages and most murine macrophage cell lines such as RAW 264.7 cells respond to interferon-gamma (IFN-gamma) and/or lipopolysaccharide (LPS) by producing large amounts of nitrite, i.e. the oxidation product of nitric oxide (NO) produced by inducible NO synthase (iNOS), other cell lines like P388.D1 cells do not produce significant amounts. To gain insight into the signalling pathway that leads to the induction of iNOS activity, we compared iNOS expression in RAW 264.7 and P388.D1 cells. We showed that IFN-gamma binds to each cell line with a similar affinity. Furthermore, no differences in iNOS gene structure were detectable by Southern blot analysis. Even though no significant nitrite secretion was found in the supernatant of P388:D1 cells stimulated with IFN-gamma and/or LPS, iNOS mRNA expression was induced. In addition, IFN-gamma induced the interferon regulatory factor-1 (IRF-1) gene and activated the binding of this factor to its target sequence in the iNOS gene. This binding was recently shown to be necessary for iNOS expression. However, in P388.D1 cells, we were unable to detect the corresponding iNOS protein. These results indicate a deficiency in P388.D1 cells which appears to be restricted to the signalling pathway controlling iNOS protein synthesis. This deficiency does not affect the overall IFN-gamma biological response, but rather a convergent post-transcriptional step common to IFN-gamma and LPS.

Effect of physical exercise on adoptive experimental auto-immune encephalomyelitis in rats

The aim of the study was to determine whether different programmes of exercise influence adoptive monophasic experimental auto-immune encephalomyelitis (adoptive EAE), a paralytic disease mediated by T-cells. Adoptive EAE was induced by the transfer of activated encephalitogenic T-lymphocytes into syngeneic recipients (Lewis rats, n = 85) and its development was followed by two independent observers. The results showed that 2 days of severe exercise (250 and 300 min) performed after the adoptive transfer of EAE slightly delayed the onset of the disease (P <0.008) and the day of its maximal severity (P <0.016) without affecting the overall severity of the disease. When this programme of exercise was performed before the cell transfer, it had no effect (P > 0.05). Two more moderate exercise programmes (5 x 120 min of running at constant speed or 5 x 60 min of running at variable speed, 5 consecutive days) performed between the adoptive transfer and the onset of the disease did not modify the development of the clinical signs of adoptive EAE (P >0.05). These results showed that severe exercise slightly influenced the effector phase of monophasic EAE and confirmed that physical exercise performed before the onset of experimental auto-immune diseases did not exacerbate the clinical signs.

Anergy induction in encephalitogenic T cells by brain microvessel endothelial cells is inhibited by interleukin-1

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system (CNS) which can be induced, in susceptible strains like Lewis rats, by transfer of activated myelin basic protein (MBP)-specific CD4+ T lymphocytes. The role of cerebral endothelium in the onset of EAE, with regard to adhesion, activation and infiltration in the CNS of encephalitogenic T lymphocytes, is not fully understood. When pretreated by interferon-gamma, the immortalized Lewis rat brain microvessel endothelial (RBE4) cells expressed major histocompatibility complex class II molecules and stimulated MBP-specific proliferation and cytolytic activity of the syngeneic encephalitogenic T cell line, designated PAS. However, RBE4-stimulated PAS lymphocytes subsequently entered an unresponsive state, known as anergy. When inoculated in syngeneic animals, anergic PAS cells, although still cytotoxic, failed to induce EAE, and no cell infiltration was detectable within CNS. The addition of interleukin-1 beta (IL-1 beta) during MBP presentation by RBE4 cells prevented T cell anergy induction, and maintained T cell encephalitogenicity, although PAS cells stimulated in these conditions caused delayed and attenuated clinical signs of EAE, with only discrete inflammatory lesions in the CNS, compared with EAE induced by PAS cells fully activated by thymic cells. Altogether, our results indicate that MBP presentation by brain microvessel endothelial cells to encephalitogenic T cells induces T cell anergy and loss of pathogenicity. In addition, IL-1 beta co-stimulation of T cells prevents anergy induction in vitro and at least partially maintains encephalitogenicity in vivo.

Effect of muscular exercise on chronic relapsing experimental autoimmune encephalomyelitis

We examined whether physical exercise affected the development of an autoimmune response, experimental autoimmune encephalomyelitis (EAE), which is a demyelinating disease leading to paralysis. EAE was inducted on day 0, in rats of both sexes, by injecting them with spinal cord tissue in adjuvant. From days 1 to 10 after injection, exercised rats (n = 55) ran on a treadmill (60-120 min/day) before the onset of the paralytic disease. Clinical signs of the disease (ataxia, paralysis, and body mass loss) were examined in exercised and control rats (n = 54). Three types of EAE were induced: monophasic, acute, and chronic relapsing (CR)-EAE (3 bouts of disease, CR-EAE 1, 2, and 3, separated by remissions). Exercise significantly delayed the onset of CR-EAE 1 (P = 0.001) and the 1st day of maximum severity of CR-EAE 1 (P = 0.001) and CR-EAE 2 (P = 0.002). Moreover, the duration of CR-EAE 1 was significantly decreased in exercised rats compared with control rats (P = 0.004). The peak severity of the different types of EAE was not modified by exercise. The present study indicates that endurance exercise during the phase of induction of EAE diminished lightly only one type of EAE (CR-EAE) and therefore did not exacerbate the autoimmune disease.

Oxidation of methyl fluoride and dimethyl ether by ammonia monooxygenase in Nitrosomonas europaea

Methyl fluoride and dimethyl ether were previously identified as inhibitors of ammonia oxidation and N2O production in autotrophic nitrifying bacteria. We demonstrate that methyl fluoride and dimethyl ether are substrates for ammonia monooxygenase and are converted to formaldehyde and a mixture of methanol and formaldehyde, respectively.

Sex as a determining factor in the effect of exercise on in vivo autoimmune response adjuvant arthritis

The present study was conducted to examine the effect of physical exercise on the development of adjuvant arthritis (AA), an animal model of the human rheumatoid arthritis, which is a T-cell-dependent autoimmune response. AA was inducted on day 0 in 8-wk-old Lewis rats of both sexes. Between postinjection days 1 and 12, two groups of rats (male and female) were trained on a treadmill every day (45-120 min/day and 15-30 m/min) before the onset of arthritic disease. Trained female (n = 27) and male (n = 22) rats and control female (n = 29) and male (n = 17) rats were observed every 2 days for the following clinical signs of AA: number of arthritic joints (swelling and redness), paw thickness, and weight gain during the disease. The results show that the incidence of arthritis (% of arthritic rats) was significantly higher in trained female rats (74%; P < 0.03) and significantly lower in trained male rats (27%; P < 0.05) compared with control rats of both sexes (female, 45%; male, 59%). There was no difference in the severity and development of the disease between trained rats and control rats of both sexes (P > 0.05). The present study indicates that the effect of exercise on the incidence of AA, an in vivo autoimmune response, depends on the sex of the animal.

Effect of physical exhaustion and glucocorticoids (dexamethasone) on T-cells of trained rats

Following a previous observation that moderate physical training (running) of rats did not impair T-cells, in this study moderately trained Wistar rats were run to exhaustion on 2 consecutive days: in one case (T-dex) this was preceded by an intraperitoneal injection of 0.5 mg.kg-1 of dexamethasone (dex) and in the other case there was no prior injection (T). Similarly one group of sedentary control rats, was injected with dex (C-dex) and the other group was not (C). Rats were killed 24 h after the last treatment (dex, exercise). Compared with the C rats, the T rats exhibited a decreased number of thymocytes (75%), in particular CD4+CD8+ thymocytes and splenocytes (55%), notably CD4+CD8- splenocytes (P < 0.01). Also noted in the T rats was a lower (45%) in vitro (+mitogen) percentage of IL2r+CD4- splenocytes (expressing the IL2 receptor), and reduced (40%, P < 0.01) or unchanged in vitro production of T-cell growth factor (TCGF) by splenocytes or blood mononucleated cells (BMC), respectively. The dex decreased the number of thymocytes and splenocytes in the same way in T-dex rats (compared to T rats) and in C-dex rats (compared to C rats, P < 0.01). In T-dex rats compared with C-dex rats, on the other hand, dex had little effect on in vitro TCGF production by BMC, and no effect on other in vitro parameters. These results would indicate that physical exhaustion was responsible for an alteration in T-cells in the moderately trained rat. This alteration was in part enhanced by dex.

Effect of moderate exercise on rat T-cells

The aim of this study was a detailed examination of the effects of moderate exercise on T-cells in adult male Wistar rats. The T-cell populations were compared in sedentary rats (C, n = 5) and in rats trained for 4 weeks on a treadmill (30-60 min.day-1, 6 days.week-1, 20-30 m.min-1) and sacrificed at rest (T-rest, n = 5). In the T-rest rats, there were higher percentages of CD4+CD8-, CD4-CD8+ and CD4-CD8- thymocytes (P < 0.05, P < 0.05 and P < 0.01 respectively) and of CD4-CD8+ splenocytes (P < 0.01), and a lower percentage of CD4-CD8+ cells in the lymph nodes (P < 0.01). Compared with T-rest or C rats, trained rats (n = 5) or untrained rats (n = 5) sacrificed immediately after a running session (60 min, 30 m.min-1) had a higher percentage of mononucleated cells CD4+CD8- in the blood (P < 0.05 and P < 0.01). Lastly, compared with C rats, rats (n = 5) sacrificed immediately after their 5th day of training (30-60 min.day-1) presented a higher total splenocyte population (P < 0.05) and greater in vitro production of T-cell growth factor (interleukin 2 + Interleukin 4) by splenocytes in response to a mitogen (P < 0.01). These results would indicate that moderate endurance training modifies the cellular composition of lymphoid organs, without impairing the in vitro functions of T-cells.

Immunomodulations of thymocytes and splenocytes in trained rats

The aim of this study was to describe the effects of training (running) on thymus and spleen cells in the rat. Young Wistar control rats (n = 6), rats trained for 4 wk (n = 5), and rats trained for 4 wk followed by 1 wk of intensive training (3 h/day, n = 6) were studied. Various lymphocyte surface and nuclear markers were determined by immunocytochemistry. The results show that 4 wk of training 1) decreased the percentage of bromodeoxyuridine (BrdU+) thymocytes (cell in phase S of the cycle, immature thymocytes; P less than 0.05) and the viability of thymocytes stimulated with concanavalin A (Con A; P less than 0.05) and 2) increased the absolute number of CD8+ (suppressor/cytotoxic T cells; 29%) and the percentage of CD8+ splenocytes (P less than 0.01). An additional week of intensive training in the 4-wk trained rats induced 1) a decrease in the absolute number of thymocytes (25%, P less than 0.05), TCR+ thymocytes, splenocytes (28%, P less than 0.01), T, CD4+ (helper T cells; 34%), and CD8+ (31%) splenocytes (P less than 0.01) and 2) an increase in the viability of splenocytes after stimulation with Con A for 72 h (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Sequence-specific DNA binding of the progesterone receptor to the uteroglobin gene: effects of hormone, antihormone and receptor phosphorylation

The effects of ligand binding and receptor phosphorylation on the interaction of progesterone receptor with specific DNA sequences in the uteroglobin gene were studied by nitro-cellulose filter binding and DNase I footprinting. High affinity sites were mapped upstream from the transcription start and in the first intron. They contained a common TGTTCACT sequence. These sites were occupied with similar affinity by the receptor, either in its free state, or complexed with the hormone or an antagonist (RU486); and also by receptor which had been phosphorylated in vivo in a hormone-dependent manner. In all cases identical footprints were observed. These experiments led to the following conclusions. The hormone-dependency of receptor binding to DNA or chromatin is observed in intact cells and in crude cellular extracts but not with purified receptor. Thus in situ, the unliganded receptor probably interacts with some nuclear component(s) which stabilizes it in a 'non-activated' form (non-chromatin and non-DNA binding form). When isolated, the receptor may undergo activation, even in the absence of the hormone. Binding by receptor of an antihormone (and possibly receptor phosphorylation) exerts an effect on gene transcription through a mechanism which is different from (and probably follows) receptor interaction with the gene.