[Interactions between vascular endothelium and immune cells: A key control point of radiation-induced digestive lesions]

Radiation-induced toxicity of the digestive tract is a major clinical concern as many cancer survivors have received radiotherapy for tumours of the abdominopelvic area. The coordination and orchestration of a tissue's response to stress depend not only on the phenotype of the cells that make up the tissue but also on cell-cell interactions. The digestive system, i.e., the intestine/colon/rectum, is made up of a range of different cell populations: epithelial cells, stromal cells, i.e. endothelial cells and mesenchymal lineages, immune cells and nerve cells. Moreover, each of these populations is heterogeneous and presents very significant plasticity and differentiation states. The pathogenesis of radiation-induced digestive lesions is an integrated process that involves multiple cellular compartments interacting in a complex sequence of events. Understanding all the cellular events and communication networks that contribute to the tissue's response to stress is therefore a major conceptual and methodological scientific challenge. The study of heterogeneous populations of cells in a tissue is now possible thanks to "single cell' RNA sequencing and spatial transcriptomics techniques, which enable a comprehensive study of the transcriptomic profiles of individual cells in an integrated system. In addition, the mathematical and bioinformatics tools that are now available for the large-scale analysis of data allow the inference of cell-cell communication networks. Such approaches have become possible through advances in bioinformatics algorithms for the analysis and deciphering of interaction networks. Interactions influence the tissue regeneration process through expression of various molecules, including metabolites, integrins, junction proteins, ligands, receptors and proteins secreted into the extracellular space. The vascular network is viewed as a key player in the progression of digestive lesions, which are characterised by infiltration of a range of immune cells. A better characterisation of endothelium/immune cell interactions in suitable preclinical models, as well as in humans, may help to identify some promising therapeutic targets for the prediction, prevention or treatment of digestive toxicity after radiotherapy.

Pilot study: pudendal neuromodulation combined with pudendal nerve release in case of chronic perineal pain syndrome. The ENTRAMI technique: early results

INTRODUCTION AND HYPOTHESIS

Chronic perineal pain syndrome due to pudendal nerve impingement is difficult to diagnose and to treat. All the known treatment options leave room for improvement considering the outcome. Early neuromodulation of the pudendal nerve after its surgical release could improve outcomes.

OBJECTIVES

The aim of the study was to evaluate the potential beneficial effect of pudendal neuromodulation combined with release surgery using the ENTRAMI technique (endoscopic transgluteal minimally invasive technique).

STUDY DESIGN

This is a single-center prospective descriptive study. Between March 2019 and March 2020, 16 patients (2 males, 14 females) were included. Data were collected at baseline and 1 month after surgery.

METHODS

Patients eligible for inclusion had chronic perineal pain for at least 3 months in the area served by the pudendal nerve. We combined pudendal nerve release with neuromodulation.

RESULTS

At 1 month, the numeric pain rating scale (NPRS) dropped from 9.5 at baseline to 3.5 (p = 0.003). Seventy-six percent of patients showed a global impression of change (PGIC) of > 50% at 1 month, and optimal treatment response (PGIC ≥ 90%) was found in 41% of patients.

LIMITATIONS

The drawback of our study was that it was not randomized or blinded. The peripheral nerve evaluation lead (PNE) used could only be implanted for 1 month because of infection risk and is also prone to dislocations and technical failures.

CONCLUSION

Pudendal nerve liberation by the ENTRAMI technique combined with short-term pudendal neuromodulation seems feasible and promising in treating patients with chronic perineal pain. Clinical trial number: NCT03880786.

Emotional overactivity in patients with irritable bowel syndrome

BACKGROUND

Negativity is often observed in patients with irritable bowel syndrome (IBS). No study has examined their emotional expressiveness as a marker of emotional reactivity. We investigated IBS patients' vulnerability to an emotional load by associating their expressiveness with psychological and neurophysiological assessments. We hypothesized that IBS would be characterized by a lack of expressiveness coupled with high scores in psychological and neurophysiological parameters.

METHODS

We assessed the emotional facial expressions (EMFACS), psychological (anxiety, depression, alexithymia), and neurophysiological (cortisol, heart rate variability (HRV)) parameters of 25 IBS patients and 26 healthy controls (HC) while they watched fear-eliciting movie extracts.

KEY RESULTS

Overall, the task elicited an increase in state anxiety and consistent HRV responses. However, IBS patients differed from HC as they displayed more sadness and tended to display more rage. Contrary to HC, IBS patients showed an increase in heart rate and a decrease in parasympathetic regulation, reflecting an enhanced responsiveness corroborated by higher scores in depression and state anxiety. Consistent with their higher difficulty in identifying feelings, a component of alexithymia positively correlated with their expressions of rage, they were not aware of their increase in anxiety during the task, whereas HC were. No linear relationship between patients' expressions and their neurophysiological responses was found.

CONCLUSIONS & INFERENCES

Irritable bowel syndrome patients displayed greater emotional expressiveness with negative prevalence. This reflects an emotional vulnerability potentially related to low regulation skills and underscores the importance of considering the central dysregulation hypothesis in IBS as a promising avenue of research.

Neonatal fever: A puzzling case

Toxoplasmosis is a potentially serious fetal infection associated with maternal seroconversion of toxoplasmosis during pregnancy. Follow-up and treatment vary between different countries. We present a case of congenital toxoplasmosis with unusual physiopathology and symptomatology. The mother was immunized before the beginning of pregnancy but immunosuppressive treatments for Crohn disease maintained during the pregnancy could explain toxoplasmosis reactivation in the mother and congenital toxoplasmosis. The baby presented reversible B lymphopenia and hypogammaglobulinemia.

Chronic vagus nerve stimulation in Crohn's disease: a 6-month follow-up pilot study

The vagus nerve (VN) is a link between the brain and the gut. The VN is a mixed nerve with anti-inflammatory properties through the activation of the hypothalamic-pituitary-adrenal axis by its afferents and by activating the cholinergic anti-inflammatory pathway through its efferents. We have previously shown that VN stimulation (VNS) improves colitis in rats and that the vagal tone is blunted in Crohn's disease (CD) patients. We thus performed a pilot study of chronic VNS in patients with active CD. Seven patients under VNS were followed up for 6 months with a primary endpoint to induce clinical remission and a secondary endpoint to induce biological (CRP and/or fecal calprotectin) and endoscopic remission and to restore vagal tone (heart rate variability). Vagus nerve stimulation was feasible and well-tolerated in all patients. Among the seven patients, two were removed from the study at 3 months for clinical worsening and five evolved toward clinical, biological, and endoscopic remission with a restored vagal tone. These results provide the first evidence that VNS is feasible and appears as an effective tool in the treatment of active CD.

Vascular imaging with contrast agent in hard and soft tissues using microcomputed-tomography

Vascularization is essential for many tissues and is a main requisite for various tissue-engineering strategies. Different techniques are used for highlighting vasculature, in vivo and ex vivo, in 2-D or 3-D including histological staining, immunohistochemistry, radiography, angiography, microscopy, computed tomography (CT) or micro-CT, both stand-alone and synchrotron system. Vascularization can be studied with or without a contrast agent. This paper presents the results obtained with the latest Skyscan micro-CT (Skyscan 1272, Bruker, Belgium) following barium sulphate injection replacing the bloodstream in comparison with results obtained with a Skyscan In Vivo 1076. Different hard and soft tissues were perfused with contrast agent and were harvested. Samples were analysed using both forms of micro-CT, and improved results were shown using this new micro-CT. This study highlights the vasculature using micro-CT methods. The results obtained with the Skyscan 1272 are clearly defined compared to results obtained with Skyscan 1076. In particular, this instrument highlights the high number of small vessels, which were not seen before at lower resolution. This new micro-CT opens broader possibilities in detection and characterization of the 3-D vascular tree to assess vascular tissue engineering strategies.

Mesenchymal stem cell therapy induces glucocorticoid synthesis in colonic mucosa and suppresses radiation-activated T cells: new insights into MSC immunomodulation

Non-neoplastic tissues around an abdomino-pelvic tumor can be damaged by the radiotherapy protocol, leading to chronic gastrointestinal complications that affect the quality of life with substantial mortality. Stem cell-based approaches using immunosuppressive bone marrow mesenchymal stem cells (MSCs) are promising cell therapy tools. In a rat model of radiation proctitis, we evidenced that a single MSC injection reduces colonic mucosa damages induced by ionizing radiation with improvement of the re-epithelization process for up to 21 days. Immune cell infiltrate and inflammatory molecule expressions in the colonic mucosa were investigated. We report that MSC therapy specifically reduces T-cell infiltration and proliferation, and increases apoptosis of radiation-activated T cells. We assessed the underlying molecular mechanisms and found that interleukin-10 and regulatory T lymphocytes are not involved in the immunosuppressive process in this model. However, an increased level of corticosterone secretion and HSD11b1 (11β-hydroxysteroid dehydrogenase type 1)-steroidogenic enzyme expression was detected in colonic mucosa 21 days after MSC treatment. Moreover, blocking the glucocorticoid (GC) receptor using the RU486 molecule statistically enhances the allogenic lymphocyte proliferation inhibited by MSCs in vitro and abrogates the mucosal protection induced by MSC treatment in vivo. Using the irradiation model, we found evidence for a new MSC immunosuppressive mechanism involving GCs.

Farming in childhood, diet in adulthood and asthma history

The decrease in the number of children living on traditional farms in France during early childhood and changes in diet could both play a role in the increase in asthma prevalence over the last decades. This study aimed to assess 1) the association of farming lifestyle in childhood and asthma, and 2) whether diet in adulthood modifies the association between farming lifestyle in childhood and adult-onset asthma. In the French Etude Epidemiologique des Femmes de la Mutuelle Générale de l'Education Nationale (E3N) study (54,018 females; age 43-68 yrs), three indicators of farming lifestyle were defined: one using individual data (having farmer parents) and two using ecological data (born in a rural area and exposure to cattle). All farming lifestyle indicators were related to childhood- (<16 yrs) and adult-onset asthma (OR (95% CI) values for farmer parents were 0.54 (0.42-0.70) and 0.72 (0.62-0.84), respectively), and to diet in adulthood, in particular to high fruit and low wine intakes. The association between farmer parents and adult-onset asthma was not modified by diet in adulthood. Results extend previous observations in younger cohorts on the protective role of contact with livestock and farming lifestyle on asthma, in particular during childhood.

Epidermoid anal cancer prognosis comparison among HIV+ and HIV- patients

BACKGROUND

Previous studies suggest a poor prognosis of epidermoid anal cancer in HIV+ patients.

AIM

To investigate the long-term outcome of epidermoid anal cancer in HIV+ and HIV- patients in the highly active antiretroviral treatment (HAART) era.

METHODS

We included all patients with epidermoid anal cancer referred to six hospitals from 1998 to 2004.

RESULTS

In all, 151 patients (44 HIV+, 107 HIV-) were reviewed retrospectively for 27 (median of 16-44) months. HIV+ patients were male (100% vs. 27%, P < 0.001) and younger (45 vs. 62 years old, P < 0.001) than HIV- patients. No significant differences were observed in the tumour stage, pelvic radiotherapy dose or concomitant chemotherapy, according to the HIV status. After chemoradiotherapy, similar numbers of HIV+ and HIV- patients had grade III-IV toxicity. A complete response was obtained in 82% and 75% (N.S.) of cases, respectively. The disease-free survival rates were 77% and 67% (N.S.) and the overall survival rates were 85% and 84% (N.S.), respectively, after 3 years of follow-up. Duration of HIV infection, viral load and CD4 count had no effect on the survival rate of HIV+ patients with EAC.

CONCLUSIONS

The clinical outcome of HIV+ patients with epidermoid anal cancer is similar to that of HIV- patients. Therefore, the same therapeutic guidelines should be applied to both populations.

[Analgesics and palliative care]

Pain is an important and often under-treated symptom of life-threatening illness. A complete evaluation of pain facilitate optimal treatment. Correct use of analgesic medication, following the guidelines of the W.H.O. step ladder, with attention to detail, with addition of adjuvant analgesics, should control the pain in most of the cases. The use of weak and strong opioid analgesics, their tolerance, the breakthrough doses, principle of opioid rotation and the place of adjuvant drugs are discussed. Proper pain management in end-of-life is never easy and require to become more familiar with the use of these analgesics and to surround oneself with a multidisciplinary team.

Human mesenchymal stem cells home specifically to radiation-injured tissues in a non-obese diabetes/severe combined immunodeficiency mouse model

The therapeutic potential of bone marrow-derived human mesenchymal stem cells (hMSC) has recently been brought into the spotlights of many fields of research. One possible application of the approach is the repair of tissue injuries related to side effects of radiotherapy. The first challenge in cell therapy is to assess the quality of the cell and the ability to retain their differentiation potential during the expansion process. Efficient delivery to the sites of intended action is also necessary. We addressed both challenges using hMSC cultured and then infused to non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice submitted to total body irradiation. Furthermore, we tested the impact of additional abdominal irradiation superimposed to total body irradiation (TBI), as a model of local therapeutic irradiation. Our results showed that the hMSC used for transplant have been expanded without significant loss in their differentiation capacities. After transplantation into adult unconditioned mice, hMSC not only migrate in bone marrow but also into other tissues. Total body irradiation increased hMSC implantation in bone marrow and muscle and further led to engraftment in brain, heart and liver. Local irradiation in addition to TBI, increased homing of injected cells to the injured tissues and to other tissues outside the local irradiation field. Morphological recovery of irradiated tissues after MSC transplantation and/or differentiation of MSC into specific organ cell types needs to be investigated. This study suggests that using the potential of hMSC to home to various organs in response to tissue injuries might be a strategy to repair the radiation-induced damages.

Comparison of squamous cell carcinoma of the canal anal (SCCA) prognosis in patients infected or not by human immunodeficiency virus (HIV)

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Background: Incidence of SCCA is increasing promoted by HIV infection. Previous small series of SCCA revealed a worst prognosis in HIV+ than in HIV- patients. Few data are available since the use of highly active antiretroviral therapy (HAART) in HIV patients. The aim of the study was to compare clinical outcome of patients recently treated for SCCA according to HIV status. Methods: Retrospective study in 6 hospitals. all consecutive patients treated for SCCA from January 1998 to October 2004 were included. Clinical outcome and pattern of care according to HIV status were compared. Results: 151 patients were included, 44 (29%) of them were HIV infected. Median follow-up was 27 (16–44) months. HIV+ patients were youngest (45 vs 62 years old, p<0.001) and only male (100% vs 27%, p<0.001). There were no significant difference in tumor stage I : 37.5 vs 25%, II : 48 vs 42.5%, IIIa : 7.5 vs 16.5%, IIIb : 12.5 vs 5% and IV : 0 vs 6% according to HIV+ or HIV- respectively. The treatments performed in HIV+ and HIV- patients were: Pelvic radiotherapy in 86 vs 91% (ns) delivering a median dose of 48 and 46 Gray. A boost in reduced fields or brachytherapy was performed in 58% vs 64% (ns). Concomitant chemotherapy (5-fluorouracile and cisplatin) was administered in 52% vs 56% (ns). Dose intensity of 5-fluorouracile and cisplatin was similar in both group. Grade 3–4 toxicity of chemoradiotherapy was observed in 11% vs 10% (ns). Complete response was obtained in 82 vs 75% (ns) and surgery (colostomy or abdominoperineal resection) was performed in 2.4% vs 7.6% of the patients (ns). During the follow-up local or metastatic recurrence occurred in 32% vs 22% of the patients (ns). The 3 years disease free survival were 77% vs 67% (ns) and 3 years overall survival were 85% and 84% (ns). Among HIV+ patients, 42/44 were on HAART, the survival was not modified by the duration of infection, viral load and CD4 count. Conclusions: The clinical outcome of HIV+ patients with SCCA is now similar to HIV- patients. The same therapeutic guidelines should be applied in both population. This improvement of prognosis is probably due to extensive use of HAART in HIV+ patients.

No significant financial relationships to disclose.

TRF2 inhibition promotes anchorage-independent growth of telomerase-positive human fibroblasts

Although telomere instability is observed in human tumors and is associated with the development of cancers in mice, it has yet to be established that it can contribute to the malignant transformation of human cells. We show here that in checkpoint-compromised telomerase-positive human fibroblasts an episode of TRF2 inhibition promotes heritable changes that increase the ability to grow in soft agar, but not tumor growth in nude mice. This transforming activity is associated to a burst of telomere instability but is independent of an altered control of telomere length. Moreover, it cannot be recapitulated by an increase in chromosome breaks induced by an exposure to gamma-radiations. Since it can be revealed in the context of telomerase-proficient human cells, telomere dysfunction might contribute to cancer progression even at late stages of the oncogenesis process, after the telomerase reactivation step.

Intranasal sufentanil is effective for postoperative analgesia in adults

PURPOSES

The aim of this prospective, randomized, double-blind study was to compare two doses of intranasal sufentanil for postoperative analgesia, titrated according to individual requirements based upon a numeric rating scale (NRS) from 0 to 10 for pain.

METHODS

Forty patients, American Society of Anesthesiologists physical status I-II, scheduled for herniorrhaphy or hemorrhoidectomy under general anesthesia, were included when postoperative NRS was > 3. Nurses used a nasal puff device delivering a constant volume. Patients were randomized into two groups: Group A patients received a dose of 0.025 microg x kg(-1) /puff, Group B patients a dose of 0.05 microg x kg(-1) /puff. Puffs were administered as often as needed to obtain NRS < or = 3, with an interval time of five minutes. Hemodynamic, respiratory measures and sedation were recorded every five minutes.

RESULTS

The probability of persistence of pain in Group B was consistently lower than in Group A. After 20 min, 20% of the patients had a NRS score > 3 in Group B, as opposed to 60% in Group A. At 60 min, no patient had a NRS > 3 in Group B, whereas there was a probability of 20% to record a NRS > 3 for Group A. Hemodynamic, respiratory parameters and sedation remained stable with no intergroup differences.

CONCLUSIONS

Nasal administration of 0.050 microg x kg(-1) /puff sufentanil allowed a NRS < 4 to be attained within one hour in all patients, with efficacy achieved after 20 min. These findings suggest that the intranasal route is an effective mode of sufentanil administration for immediate postoperative analgesia in adult patients.

A second locus for Aicardi-Goutieres syndrome at chromosome 13q14-21

BACKGROUND

Aicardi-Goutières syndrome (AGS) is an autosomal recessive, early onset encephalopathy characterised by calcification of the basal ganglia, chronic cerebrospinal fluid lymphocytosis, and negative serological investigations for common prenatal infections. AGS may result from a perturbation of interferon alpha metabolism. The disorder is genetically heterogeneous with approximately 50% of families mapping to the first known locus at 3p21 (AGS1).

METHODS

A genome-wide scan was performed in 10 families with a clinical diagnosis of AGS in whom linkage to AGS1 had been excluded. Higher density genotyping in regions of interest was also undertaken using the 10 mapping pedigrees and seven additional AGS families.

RESULTS

Our results demonstrate significant linkage to a second AGS locus (AGS2) at chromosome 13q14-21 with a maximum multipoint heterogeneity logarithm of the odds (LOD) score of 5.75 at D13S768. The AGS2 locus lies within a 4.7 cM region as defined by a 1 LOD-unit support interval.

CONCLUSIONS

We have identified a second AGS disease locus and at least one further locus. As in a number of other conditions, genetic heterogeneity represents a significant obstacle to gene identification in AGS. The localisation of AGS2 represents an important step in this process.

Telomeres and chromosomal instability

Telomeres are distinctive structures, composed of a repetitive DNA sequence and associated proteins, which enable cells to distinguish chromosome ends from DNA double-strand breaks. Telomere alterations, caused by replication-mediated shortening, direct damage or defective telomere-associated proteins, usually generate chromosomal instability, which is observed in senescence and during the immortalization process. In cancer cells, this chromosome instability could be extended by their ability to 'repair' chromosomes and terminate in break-fusion-bridge cycles. Dysfunctional telomeres can be healed by activation of telomerase or by the 'alternative mechanism' of telomere lengthening. Activation of such telomere maintenance mechanisms may help to preserve the integrity of chromosomes even if they play a role in chromosomal instability. This review focuses on molecular processes involved in telomere maintenance and chromosomal instability associated with dysfunctional telomeres in mammalian cells.

Tolerance to acute isovolemic hemodilution. Effect of anesthetic depth

BACKGROUND

Acceptance of a lower transfusion trigger in the perioperative period requires study of the effects of anesthetic depth on the tolerance to acute isovolemic anemia. Anesthetic agents with negative effects on the cardiovascular system may exert proportionately greater depressant effects on cardiac output response than on tissue oxygen demand, reducing tolerance to acute isovolemic anemia.

METHODS

In the first study, animals were anesthetized with halothane (n = 14; 23.8 +/- 4.8 kg, mean +/- SD). In a second study, animals were anesthetized with ketamine (n = 14; 24.3 +/- 4.7 kg). In each study, dogs were randomly allocated to receive either low or high concentrations of anesthetic. Oxygen delivery and oxygen consumption were determined from independent measurements during a stepwise isovolemic hemodilution protocol. In each dog, critical oxygen delivery was determined from a plot of oxygen consumption versus oxygen delivery using a least-sum-of-squares technique. Critical hemoglobin (hemoglobin) was determined from a plot of hemoglobin versus oxygen consumption using the same method.

RESULTS

With both agents, the higher anesthetic concentration was associated with decreased oxygen consumption, resulting in a lower critical oxygen delivery. However, critical hemoglobin was significantly higher in the animals receiving the higher anesthetic dosage (1.5 vs. 1.0 minimum alveolar concentration of halothane: 4.1 +/- 1.3 vs. 2.3 +/- 0.5 g/dl, P < 0.05; high- vs. low-dose ketamine: 3.7 +/- 1.4 vs. 2.5 +/- 0.6 g/dl, P < 0.05). This was related to a marked blunting of the cardiac output response to hemodilution in the animals receiving the higher anesthetic dosage.

CONCLUSIONS

Increased anesthetic depth with halothane or ketamine resulted in a decreased tolerance to acute anemia, as reflected by a significant increase in critical hemoglobin concentration.

[The anesthesiology-recovery department]

The Department of Anesthesiology and Reanimation is organised in units with clinical activities, which include the pre-operative care of patients, anesthesiological care and immediate post-operative supervision. Two post-operative treatment rooms also form part of the department. The main fields of research of the various units result from collaborations with other departments of Hôpital Erasme, in particular with regard to the development of advanced techniques or fit within the confines of the speciality.

Comparative effects of red blood cell transfusion and increasing blood flow on tissue oxygenation in oxygen supply-dependent conditions

Red blood cell (RBC) transfusion is usually administered to improve oxygen delivery (DO(2)) in order to sustain tissue oxygen demand. However, this practice is not supported by firm clinical or experimental data. Using a randomized two-period crossover design, this study compared the efficacy of "fresh" RBC transfusion and increased blood flow to restore tissue oxygenation in oxygen supply-dependent conditions. In 12 ketamine-anesthetized mongrel dogs submitted to nonpulsatile normothermic cardiopulmonary bypass, DO(2) was reduced by a progressive decrease in pump flow. DO(2) dependency was defined as an O(2) uptake (V O(2)) decrease by more than 15% from baseline value. Then, intervention consisted of a 40% increase in DO(2) obtained either by transfusion of "fresh" dog's RBC (stored < 3 d) or by increase in pump flow. Animals received both interventions sequentially in a random order, while O(2) saturation was maintained constant. In O(2) supply-dependent conditions, rising pump flow from 1.6 +/- 0.4 to 2.7 +/- 0.7 L/ min increased DO(2) from 5.4 +/- 1.1 to 9.0 +/- 1.3 ml/kg/min (p < 0.01) and V O(2) from 3.5 +/- 0.4 to 4.1 +/- 0.5 ml/kg/min (p = 0.02). "Fresh" RBC transfusion, which increased the hemoglobin concentration from 6.4 +/- 0.9 to 11.1 +/- 1.3 g/dl, increased DO(2) from 5.4 +/- 1.2 to 9.0 +/- 1.4 ml/kg/min (p < 0.01) and V O(2) from 3.6 +/- 0.4 to 4.1 +/- 0.5 ml/kg/min (p = 0.02). There was no difference in V O(2) resulting from both interventions. In oxygen supply-dependent conditions, "fresh" RBC transfusion and increased blood flow are equally effective in restoring tissue oxygenation.

The Pim-1 kinase stimulates maturation of TCRbeta-deficient T cell progenitors: implications for the mechanism of Pim-1 action

We demonstrate that overexpression of Pim-1, a cytoplasmic serine/threonine kinase of poorly defined function, results in the development of substantial numbers of CD4(+)CD8(+) double-positive thymocytes in two independent knock-out mouse models (i.e. the RAG-1-deficient and TCRbeta gene enhancer-deleted mice) in which production of a functionally rearranged TCRbeta gene (hence the pre-TCR) is impaired. This activity of Pim-1, however, does not affect signaling through the Ras/Raf/MAP kinase cascade nor signaling which mediates suppression of TCRbeta gene recombination (i.e. allelic exclusion). While overexpression of Pim-1 positively affects cell cycle progression in selected CD4(-)CD8(-) double-negative precursors, it did not affect expression of components of the cell cycle machinery, with the exception of the G(1)-specific phosphatase Cdc25A upon antigen receptor stimulation. We propose that Pim-1 acts downstream, or in parallel, to pre-TCR-mediated selection as one factor involved in the proliferative expansion of beta-selected pre-T cells.

[Invasive techniques in chronic pain control]

A wide range of invasive techniques are available for pain treatment. Treatment must be adapted to the severity of the underlying disease and the intensity of pain. Very few controlled studies concerning these techniques have been performed, and it is therefore difficult to assess their short and long term efficacy. Optimal effectiveness will be obtained if the indication is correct. This non exhaustive revue presents the indications, techniques and results of neural conduction blocks as peripheral blocks, Alcock canal block, zygapophysial joint blocks and also central blocks illustrated by epidural and intrathecal injections and finally sympathetic nervous system blocks as celiac plexus block, stellate ganglion block and intravenous blocks for complex regional pain syndromes. The indications, techniques and results of thermal neurolyse (radiofrequency, thermocoagulation), transcutaneous electrical nervous stimulation (TENS) and implant central stimulation are also presented. A multidisciplinary approach is used to evaluate the risk/benefit ratio of these invasive techniques for each patient.

T cell development in TCR beta enhancer-deleted mice: implications for alpha beta T cell lineage commitment and differentiation

T cell differentiation in the mouse thymus is an intricate, highly coordinated process that requires the assembly of TCR complexes from individual components, including those produced by the precisely timed V(D)J recombination of TCR genes. Mice carrying a homozygous deletion of the TCR beta transcriptional enhancer (E beta) demonstrate an inhibition of V(D)J recombination at the targeted TCR beta locus and a block in alpha beta T cell differentiation. In this study, we have characterized the T cell developmental defects resulting from the E beta-/- mutation, in light of previously reported results of the analyses of TCR beta-deficient (TCR beta-/-) mice. Similar to the latter mice, production of TCR beta-chains is abolished in the E beta-/- animals, and under these conditions differentiation into cell-surface TCR-, CD4+CD8+ double positive (DP) thymocytes depends essentially on the cell-autonomous expression of TCR delta-chains and, most likely, TCR gamma-chains. However, contrary to previous reports using TCR beta-/- mice, a minor population of TCR gamma delta+ DP thymocytes was found within the E beta-/- thymi, which differ in terms of T cell-specific gene expression and V(D)J recombinase activity, from the majority of TCR-, alpha beta lineage-committed DP thymocytes. We discuss these data with respect to the functional role of E beta in driving alpha beta T cell differentiation and the mechanism of alpha beta T lineage commitment.

Definition of a T-cell receptor beta gene core enhancer of V(D)J recombination by transgenic mapping

V(D)J recombination in differentiating lymphocytes is a highly regulated process in terms of both cell lineage and the stage of cell development. Transgenic and knockout mouse studies have demonstrated that transcriptional enhancers from antigen receptor genes play an important role in this regulation by activating cis-recombination events. A striking example is the T-cell receptor beta-chain (TCRbeta) gene enhancer (Ebeta), which in the mouse consists of at least seven nuclear factor binding motifs (betaE1 to betaE7). Here, using a well-characterized transgenic recombination substrate approach, we define the sequences within Ebeta required for recombination enhancer activity. The Ebeta core is comprised of a limited set of motifs (betaE3 and betaE4) and an additional previously uncharacterized 20-bp sequence 3' of the betaE4 motif. This core element confers cell lineage- and stage-specific recombination within the transgenic substrates, although it cannot bypass the suppressive effects resulting from transgene integration in heterochromatic centromeres. Strikingly, the core enhancer is heavily occupied by nuclear factors in immature thymocytes, as shown by in vivo footprinting analyses. A larger enhancer fragment including the betaE1 through betaE4 motifs but not the 3' sequences, although active in inducing germ line transcription within the transgenic array, did not retain the Ebeta recombinational activity. Our results emphasize the multifunctionality of the TCRbeta enhancer and shed some light on the molecular mechanisms by which transcriptional enhancers and associated nuclear factors may impact on cis recombination, gene expression, and lymphoid cell differentiation.

Critical haemoglobin concentration in anaesthetized dogs: comparison of two plasma substitutes

We have explored systemic and regional tolerance to haemodilution during anaesthesia with two different synthetic colloids. Eighteen dogs undergoing mechanical ventilation during anaesthesia with ketamine were submitted to progressive normovolaemic haemodilution with either gelatin (GEL; n = 9) or hydroxyethylstarch (HES; n = 9) administered on a 1:1 ratio. Systemic oxygen delivery was calculated from measurement of thermodilution cardiac output and arterial oxygen content, while systemic oxygen consumption was determined from expired gas analysis. Mesenteric oxygen delivery and consumption were determined using ultrasonic flow measurements, and arterial and mesenteric venous oxygen contents. The critical haemoglobin concentration (i.e. the haemoglobin value below which oxygen consumption becomes oxygen delivery dependent) was mean 3.6 (SD 0.8) g dl-1 in the GEL and 3.5 (1.5) g dl-1 in the HES group. The mesenteric critical oxygen extraction ratio (O2ER) (GEL 50.1 (12.1)%; HES 48.5 (13.4)%) was significant lower than the systemic critical O2ER (GEL 66.1 (8.4)%; HES 67.7 (7.1)%). There were no significant differences between the GEL and HES groups for any of these variables, or in the amount of colloid administered. During the study, oxygen delivery decreased almost linearly with reduction in haemoglobin, indicating a lack of cardiac output response to anaemia during ketamine anaesthesia.

High-titre, cryostable cell-free varicella zoster virus

Work with varicella-zoster virus has been seriously hampered by the difficulty of preparing high-titre cell free virus, and by the instability of such virus when frozen and thawed. We have evaluated the use of a range of protocols and demonstrate that relatively high titres of 19,000 plaque forming units per millilitre may be recovered after freezing in PBS-sucrose-glutamate-serum buffer (PSGC). In addition, we have shown that the virus obtained by this method gives similar results in neutralisation and antiviral susceptibility assays to that freshly prepared from infected cells, allowing the use of high titre, titrated virus stocks in such assays.

Enhancer control of V(D)J recombination at the TCRbeta locus: differential effects on DNA cleavage and joining

Deletion of the TCRbeta transcriptional enhancer (Ebeta) results in nearly complete inhibition of V(D)J recombination at the TCRbeta locus and a block in alpha beta T cell development. This result, along with previous work from many laboratories, has led to the hypothesis that transcriptional enhancers affect V(D)J recombination by regulating the accessibility of the locus to the recombinase. Here we test this hypothesis by performing a detailed analysis of the recombination defect in Ebeta-deleted (Ebeta-/-) mice using assays that detect various reaction intermediates and products. We found double-strand DNA breaks at recombination signal sequences flanking Dbeta and Jbeta gene segments in Ebeta-/- thymuses at about one-third to one-thirtieth the level found in thymuses with an unaltered TCRbeta locus. These sites are also subject to in vitro cleavage by the V(D)J recombinase in both Ebeta-/- and Ebeta+/+ thymocyte nuclei. However, the corresponding Dbeta-to-Jbeta coding joints are further reduced (by 100- to 300-fold) in Ebeta-/- thymuses. Formation of extrachromosomal Dbeta-to-Jbeta signal joints appears to be intermediately affected and nonstandard Dbeta-to-Dbeta joining occurs at the Ebeta-deleted alleles. These data indicate that, unexpectedly, loss of accessibility alone cannot explain the loss of TCRbeta recombination in the absence of the Ebeta element and suggest an additional function for Ebeta in the process of DNA repair at specific TCRbeta sites during the late phase of the recombination reaction.

UVA-induced oxidative damage in fibroblasts cultured in a 3-dimensional collagen matrix

The exposure of dermal equivalent, i.e., fibroblasts cultured in a 3-dimensional collagen matrix to realistic doses of UVA (< or = 200 kJ/m2), results in a lipid peroxidation process as evidenced by the release of thiobarbituric acid-reactive substances in the supernatant. This peroxidative process is shown to be associated with the presence of fibroblasts and is inhibited by preincubation with vitamin E, the well-known chain-breaking antioxidant. Moreover, the UVA irradiation triggers cytotoxic effects which can also be reversed by preincubation with vitamin E. While the peroxidation extent is similar for fibroblasts cultured in monolayers or in dermal equivalent, the cytotoxic response to UVA is more pronounced in dermal equivalent.