Effects of enteral carbohydrates on de novo lipogenesis in critically ill patients.

BACKGROUND: Conversion of glucose into lipid (de novo lipogenesis; DNL) is a possible fate of carbohydrate administered during nutritional support. It cannot be detected by conventional methods such as indirect calorimetry if it does not exceed lipid oxidation. OBJECTIVE: The objective was to evaluate the effects of carbohydrate administered as part of continuous enteral nutrition in critically ill patients. DESIGN: This was a prospective, open study including 25 patients nonconsecutively admitted to a medicosurgical intensive care unit. Glucose metabolism and hepatic DNL were measured in the fasting state or after 3 d of continuous isoenergetic enteral feeding providing 28%, 53%, or 75% carbohydrate. RESULTS: DNL increased with increasing carbohydrate intake (f1.gif" BORDER="0"> +/- SEM: 7.5 +/- 1.2% with 28% carbohydrate, 9.2 +/- 1.5% with 53% carbohydrate, and 19.4 +/- 3.8% with 75% carbohydrate) and was nearly zero in a group of patients who had fasted for an average of 28 h (1.0 +/- 0.2%). In multiple regression analysis, DNL was correlated with carbohydrate intake, but not with body weight or plasma insulin concentrations. Endogenous glucose production, assessed with a dual-isotope technique, was not significantly different between the 3 groups of patients (13.7-15.3 micromol * kg(-1) * min(-1)), indicating impaired suppression by carbohydrate feeding. Gluconeogenesis was measured with [(13)C]bicarbonate, and increased as the carbohydrate intake increased (from 2.1 +/- 0.5 micromol * kg(-1) * min(-1) with 28% carbohydrate intake to 3.7 +/- 0.3 micromol * kg(-1) * min(-1) with 75% carbohydrate intake, P: < 0. 05). CONCLUSION: Carbohydrate feeding fails to suppress endogenous glucose production and gluconeogenesis, but stimulates DNL in critically ill patients.

De novo T cell generation and cell cycle analysis of CD4 and CD8 T cells during HIV-disease

RESUME POUR UN LARGE PUBLIC Parmi les globules blancs, les lymphocytes T 004 jouent un rôle primordial dans la coordination de la réponse immunitaire contre les pathogènes et les lymphocytes T CD8 dans leur élimination. Lors d'une infection par le virus de l'immunodéficience humaine (VIH-1), non seulement les cellules T CD4 sont les principales cibles d'infections, mais aussi elles disparaissent progressivement tout au long de la maladie. Ce phénomène, appelé aussi épuisement des lymphocytes T CD4, est la principale cause provoquant le Syndrome d'Immunodéficience Acquise (SIDA). Malgré de grands efforts de recherche, nous ne sommes toujours pas en mesure de dire si ce phénomène est dû à un défaut dans la production de nouvelles cellules ou à une destruction massive de cellules en circulation. Dans cette étude, nous nous proposions, dans un premier temps, de comparer la production de nouvelles cellules T CD4 et CD8 chez des individus VIH-négatifs et positifs. Les cellules nouvellement produites portent un marqueur commun que l'on appelle TREC et qui est facilement mesurable. En considérant des paramètres cliniques, nous étions en mesure de déterminer le niveau de TRECs de cellules T CD4 et CD8 dans différentes phases de la maladie. De là, nous avons pu déterminer que le niveau de TREC est toujours plus bas dans les cellules T CD8 de patients VIH-positifs comparativement à notre groupe contrôle. Nous avons pu déterminer par une analyse ultérieure que cette différence est due à une forte prolifération de ces cellules chez les patients VIH-positifs, ce qui a pour effet de diluer ce marqueur. En revanche, la production de nouvelles cellules T CD4 chez des patients VIH-positifs est accentuée lors de la phase précoce de la maladie et largement réprimée lors de la phase tardive. Dans un second temps, nous avons effectué une analyse à grande échelle de l'expression de gènes associés à la division cellulaire sur des lymphocytes T CD4 et CD8 d'individus VIH-¬positifs et négatifs, avec comme contrôle des cellules proliférant in vitro. De cette étude, nous avons pu conclure que les cellules T CD8 de patients VIH-positifs étaient en état de prolifération, alors que les lymphocytes T CD4 présentaient des défauts majeurs conduisant à un arrêt de la division cellulaire. Nos résultats montrent que la capacité à produire de nouvelles cellules chez des patients VIH¬positifs reste active longtemps pendant la maladie, mais que l'incapacité des cellules T CD4 à proliférer peut enrayer la reconstitution immunitaire chez ces individus. ABSTRACT The hallmark of HIV-1 infection is the depletion of CD4 T cells. Despite extensive investigation, the mechanisms responsible for the loss of CD4 T cells have been elucidated only partially. In particular, it remains controversial whether CD4 T cell depletion results from a defect in T cell production or from a massive peripheral destruction. In this study, de novo T cell generation has been investigated by measuring T cell receptor rearrangement excision circles (TRECs) on large cohorts of HIV-negative (N=120) and HIV-1 infected (N=298) individuals. Analysis of TREC levels was performed in HIV-infected subjects stratified by the stage of HIV disease based on CD4 T cell counts (early: >500 CD4 T cells/µl; intermediate: <500>200; late: <200) and by age (20 to 60 years, n = 259). Our data show that TREC levels in CD8 T cells were significantly lower in HIV-infected subjects at any stage of disease compared to the control group. In contrast, TREC levels in CD4 T cells were significantly higher in HIV-infected subjects at early stages disease while no significant differences were observed at intermediate stages of the disease and were severely reduced only at late stages of disease. To investigate further the status of cell cycle in peripheral CD4 and CD8 T cells in HIV-1 infections, we determined the pattern of gene expression with the microarray technology. In particular, CD4 and CD8 T cells of HIV-1 infected and HIV-negative subjects were analysed by Cell Cycle cDNA expression array. The patterns of gene expression were compared to in vitro stimulated CD4 and CD8 T cells and this analysis showed that CD8 T cells of HIV-1 infected subjects had a pattern of gene expression very similar to that of in vitro stimulated CD8 T cells thus indicating ongoing cell cycling. In contrast, CD4 T cells of HIV-1 infected subjects displayed a complex pattern of gene expression. In fact, CD4 T cells expressed high levels of genes typically associated with cell activation, but low levels of cell cycle genes. Therefore, these results indicated that activated CD4 T cells of HIV-1 infected subjects were in cell cycle arrest. Taking together these results indicate that thymus function is preserved for long time during HIV- 1 infection and the increase observed in early stage disease may represent a compensatory mechanism to the depletion of CD4 T cells. However, we provide evidence for a cell cycle arrest of peripheral CD4 T cells that may prevent potentially the replenishment of CD4 T cells. RESUME Les mécanismes responsables de la perte des lymphocytes T CD4 lors de l'infection pas VIH n'ont été élucidés que partiellement. Nous ne savons toujours pas si l'épuisement des lymphocytes T CD4 résulte d'un défaut dans la production de cellules ou d'une destruction périphérique massive. Dans cette étude, la production de cellules T a été étudiée en mesurant les cercles d'excision générés lors du réarrangement du récepteur au cellules T (TRECs) chez des individus VIH-négatifs (N=120) et VIH-1 positifs (N=298). L'analyse des niveaux de TREC a été faite chez sujets HIV-infectés en considérant les phases de la maladie sur la base des comptes CD4 (phase précoce: > 500 cellules CD4/µl; intermédiaire: < 500>200; tardive: < 200) et par âge. Nos données démontrent que les niveaux de TRECs des cellules T CD8 étaient significativement plus bas chez les sujets VIH-1 infectés, à tous les stades de la maladie comparativement au groupe contrôle. En revanche, les niveaux de TRECs des cellules T CD4 étaient significativement plus élevés chez les sujets VIH-1 infectés durant la phase précoce de la maladie, tandis qu'aucune différence significative n'était observée durant la phase intermédiaire et étaient très réduits dans la phase tardive. Dans une deuxième partie, nous avons utilisé la technique des biopuces à d'ADN complémentaire pour analyser la régulation du cycle cellulaire chez les lymphocytes T CD4 et CD8 périphériques lors d'une infection au VIH-1. Des profils d'expression ont été déterminés et comparés à ceux de cellules T CD4 et CD8 stimulées in vitro, démontrant que les cellules T CD8 des sujets VIH-positifs avaient un profil d'expression très semblable à celui des cellules stimulées in vitro en prolifération. En revanche, les lymphocytes T CD4 des sujets VIH-1 positifs avaient un profil d'expression de gène plus complexe. En fait, leur profil montrait une sur- expression de gènes associés à une activation cellulaire, mais une sous-expression de ceux induisant une division. Ainsi, ces résultats indiquent que les lymphocytes T CD4 d'individus VIH-positifs présentent des dérégulations qui conduisent à un arrêt du cycle cellulaire. Ces résultats montrent que la fonction thymique est préservée longtemps pendant l'infection au VIH-1 et que l'augmentation de la quantité de TRECs dans la phase précoce de la maladie peut représenter un mécanisme compensatoire à l'épuisement des cellules T CD4. Cependant, nous démontrons aussi un clair dysfonctionnement du cycle cellulaire chez les cellules T CD4 d'individus infectés par VIH-1 ce qui peut enrayer la reconstitution du système immunitaire.

Lipoxin A₄ prevents the progression of de novo and established endometriosis in a mouse model by attenuating prostaglandin E₂ production and estrogen signaling.

Endometriosis, a leading cause of pelvic pain and infertility, is characterized by ectopic growth of endometrial-like tissue and affects approximately 176 million women worldwide. The pathophysiology involves inflammatory and angiogenic mediators as well as estrogen-mediated signaling and novel, improved therapeutics targeting these pathways are necessary. The aim of this study was to investigate mechanisms leading to the establishment and progression of endometriosis as well as the effect of local treatment with Lipoxin A4 (LXA₄), an anti-inflammatory and pro-resolving lipid mediator that we have recently characterized as an estrogen receptor agonist. LXA₄ treatment significantly reduced endometriotic lesion size and downregulated the pro-inflammatory cytokines IL-1β and IL-6, as well as the angiogenic factor VEGF. LXA₄ also inhibited COX-2 expression in both endometriotic lesions and peritoneal fluid cells, resulting in attenuated peritoneal fluid Prostaglandin E₂ (PGE₂) levels. Besides its anti-inflammatory effects, LXA₄ differentially regulated the expression and activity of the matrix remodeling enzyme matrix metalloproteinase (MMP)-9 as well as modulating transforming growth factor (TGF)-β isoform expression within endometriotic lesions and in peritoneal fluid cells. We also report for first time that LXA₄ attenuated aromatase expression, estrogen signaling and estrogen-regulated genes implicated in cellular proliferation in a mouse model of disease. These effects were observed both when LXA₄ was administered prior to disease induction and during established disease. Collectively, our findings highlight potential targets for the treatment of endometriosis and suggest a pleotropic effect of LXA₄ on disease progression, by attenuating pro-inflammatory and angiogenic mediators, matrix remodeling enzymes, estrogen metabolism and signaling, as well as downstream proliferative pathways.

Histopathology and prognosis of de novo bladder tumors following solid organ transplantation.

BACKGROUND: Patients following solid organ transplantation have an increased risk of developing de novo bladder tumors, but their biology is poorly characterized. METHODS: We studied 1743 patients who underwent a transurethral resection of a newly diagnosed bladder tumor at a single institution. The histopathology, treatment, recurrence-free survival and overall survival were evaluated and compared between transplant and non-transplant patients. RESULTS: We identified 74 transplant patients who developed a de novo bladder tumor after a median post-transplantation interval of 62 months. The tumor was malignant in 29 patients (39 %). The most common benign lesion was nephrogenic adenoma (84 %), which neither coexisted with nor developed into malignant tumors during follow-up. Compared with non-transplant patients (n = 1669), transplant patients were significantly younger (median 55 vs 69 years, P < 0.001) and had a 9.0-fold higher odds of benign tumors (P < 0.001), while there were no differences in pathology among patients with urothelial carcinoma of the bladder (UCB). In a multivariable analysis for non-muscle-invasive UCB that was adjusted for the risk group, patients with a transplant had a 1.8-fold increased risk of recurrence (P = 0.048). Four of five transplant patients did not respond to Bacillus Calmette-Guérin instillations. There were no differences in overall survival after radical cystectomy (P = 0.87). CONCLUSIONS: The majority of bladder tumors in transplant patients are benign, and they neither coexist with nor develop into malignant tumors. Transplant patients with non-muscle-invasive UCB show an increased risk of disease recurrence, while those treated with radical cystectomy have similar outcomes to patients without a transplant.

De novo undifferentiated pleomorphic sarcoma arising from a renal allograft: A case report

To the best of our knowledge, this is the first report of an undifferentiated pleomorphic sarcoma arising from a renal graft. Transplantectomy was performed in a 47-year old woman presenting to the emergency room because of general weakness. Preoperative workup revealed a 5.5 cm malignant mass of the graft which was not present on routine ultrasound performed 12 months earlier. Following transplantectomy, local recurrence developed despite complete tumor resection and interruption of immunosuppression. Despite radiation therapy, the outcome was ultimately fatal. Genetic analysis revealed that the tumor had arisen from donor tissue. Annual ultrasound surveillance might not be enough effective to screen for these rare high grade neoplasms.