Alterations of digestive motility after bariatric surgery.

Bariatric surgery can induce changes in digestive motility that are de novo or secondary to an improvement or aggravation of previous disorders due to obesity. Alterations of digestive motility are frequently part of the mechanism of action and a result of surgery. They are not rare and they are not always associated with an increase in weight loss but can lead to the negative consequences on quality of life, which are more or less reversible as a real surgical complication. Knowledge of these complications has become essential, especially in this period when bariatric surgery often concerns patients who have already undergone an operation. Thus, the changes in digestive motility after bariatric surgery and the complications that may result from them must be known and considered to adapt surgical techniques to each patient, both in the case of a first intervention and in the case of a reoperation, which is becoming more and more frequent. The objective of this review is to synthesize alterations of esophageal and gastro-intestinal motility secondary to bariatric surgical procedures.

Time knowledge impairments in children with ADHD.

BACKGROUND: A large number of studies have shown time perception impairment and reaction time (RT) variability in children with attention deficit hyperactivity disorder (ADHD), and have discussed the causes of such difficulties. However, very few studies have investigated time knowledge (i.e., the correct representation and use of time units) in children with ADHD. METHODS: We evaluated time knowledge in 33 children with ADHD, aged 8-12 years, who had consulted a reference center for learning disabilities in Paris, matched for age and gender with 33 typically developing (TD) children. We used a simple questionnaire-based survey and neuropsychological tests for cognitive and attentional skills. RESULTS: The acquisition of time knowledge was delayed in children with ADHD compared with TD children (P<0.01). At the end of primary school, children with ADHD obtained time knowledge scores that were close to those of TD children at the beginning of primary school. In children with ADHD, time knowledge was significantly related to the working memory index (P<0.05), but not to ADHD presentation (with or without hyperactivity). CONCLUSION: This study shows time knowledge impairment in children with ADHD, and paves the way for new screening tests and rehabilitation focused on time knowledge and time-related skills, in order to improve patient care and autonomy.

Primary Surgery for Malignant Large Bowel Obstruction: Postoperative Nasogastric Tube Reinsertion is Not Mandatory.

BACKGROUND: Malignant large bowel obstructions frequently require emergency surgery. Compliance with enhanced recovery after surgery programmes is significantly reduced due to non-removal of the nasogastric tube in the postoperative period. The first aim of the present study was to research factors associated with the failure of immediate nasogastric tube removal in patients who had undergone emergency surgery for malignant large bowel obstruction. The second aim was to assess the morbidity linked to nasogastric tube reinsertion. METHODS: This retrospective and monocentric study included all consecutive patients admitted for acute malignant large bowel obstruction who underwent emergency surgery. Patients who were not primarily operated on were excluded (n = 178; 69.3%). The group of patients requiring nasogastric tube (NGT) reinsertion was compared with the group that did not require NGT reinsertion. RESULTS: Seventy-nine patients underwent emergency surgery, of which 18 (22.8%) required nasogastric tube reinsertion. There was no difference between the two groups with regard to (a) immediate nasogastric tube removal (p = 0.87) and (b) inclusion in an enhanced recovery programme (p = 0.75). However, preoperative small bowel dilatation was associated with a reduction in the need for NGT reinsertion (p = 0.04). A left-sided tumour was also associated with the need for NGT reinsertion in uni- (p = 0.034) and multivariate analysis (OR = 8; p < 0.05). Surgical access and procedure were not significantly associated with NGT reinsertion. The postoperative course influenced NGT reinsertion, which was significantly associated with postoperative ileus (OR = 4; p < 0.05) and postoperative morbidity (OR = 4; p < 0.05). Morbidity was not linked to nasogastric tube removal. CONCLUSION: Nasogastric tube reinsertion was not affected by immediate removal of the tube. Left-sided tumours and patients at risk of postoperative ileus should be managed with caution. Immediate nasogastric tube removal is not contraindicated in the case of large bowel obstruction because it is not associated with a higher risk of NGT reinsertion.

Failure of Conservative Treatment of Acute Diverticulitis with Extradigestive Air.

BACKGROUND: Medical management for perforated diverticulitis without abscess or peritonitis (PDwAP) has a success rate of 40-70%. Identifying patients with a risk of medical treatment failure would improve outcomes. The aim of this study was to identify the risk factors for failure of medical treatment in patients admitted with PDwAP. METHODS: This multicenter retrospective observational study included all consecutive patients admitted for PDwAP and not surgically treated over a 7-year period. Peritonitis classified on the Hinchey scale was excluded. Potential clinical, biological and radiological risk factors for medical treatment failure were collected and compared between the group of patient with a failure of medical treatment (F) and the group in which treatment did not fail. Data were collected at referral. RESULTS: Ninety-one patients were included, and 29 had a failure of treatment (31.9%). The median heart rate was different between the two groups (p < 0.001), at approximately 100/min in the F group. A blood level of C-reactive protein (CRP) ≥150 mg/mL was associated with a higher rate of failure (p = 0.021), but it was not confirmed in multivariate analysis. Pneumoperitoneum ≥5 mm and intraperitoneal liquid located in the pouch of Douglas were more likely to be present in the F group (respectively, p = 0.001 and p < 0.001). A multivariate analysis showed independent risk factors as being the highest pneumoperitoneum diameter >5 mm (OR 5.193; p = 0.015) and peritoneal fluid location in the pouch of Douglas (OR 4.103; p = 0.036). CONCLUSION: The severity of sepsis (tachycardia and CRP ≥150 mg/mL) and of imaging signs (pneumoperitoneum ≥5 mm and peritoneal fluid in the pouch of Douglas) were risk factors for medical treatment failure of PDwAP requiring special supervision so as not to lose time in undertaking surgical management.

Postoperative ileus: Pathophysiology, incidence, and prevention.

Postoperative ileus (POI) is a major focus of concern for surgeons because it increases duration of hospitalization, cost of care, and postoperative morbidity. The definition of POI is relatively consensual albeit with a variable definition of interval to resolution ranging from 2 to 7 days for different authors. This variation, however, leads to non-reproducibility of studies and difficulties in interpreting the results. Certain risk factors for POI, such as male gender, advanced age and major blood loss, have been repeatedly described in the literature. Understanding of the pathophysiology of POI has helped combat and prevent its occurrence. But despite preventive and therapeutic efforts arising from such knowledge, 10 to 30% of patients still develop POI after abdominal surgery. In France, pharmacological prevention is limited by the unavailability of effective drugs. Perioperative nutrition is very important, as well as limitation of preoperative fasting to 6 hours for solid food and 2 hours for liquids, and virtually no fasting in the postoperative period. Coffee and chewing gum also play a preventive role for POI. The advent of laparoscopy has led to a significant improvement in the recovery of gastrointestinal function. Enhanced recovery programs, grouping together all measures for prevention or cure of POI by addressing the mechanisms of POI, has reduced the duration of hospitalization, morbidity and interval to resumption of transit.

Effectiveness of a bacteriophage in reducing Listeria monocytogenes on fresh-cut fruits and fruit juices.

Listeria monocytogenes is a serious foodborne pathogen and new strategies to control it in food are needed. Among them, bacteriophages hold attributes that appear to be attractive. The objective of this study was to investigate the efficacy of the bacteriophage Listex P100 to control L. monocytogenes growth on melon, pear and apple products (juices and slices) stored at 10 °C. L. monocytogenes grew well in untreated fruit slices. In juices, the pathogen grew in untreated melon, survived in untreated pear and decreased in untreated apple. Phage treatment was more effective on melon followed by pear, but no effect on apple products was observed. Reductions of about 1.50 and 1.00 log cfu plug(-1) for melon and pear slices were found, respectively. In juices, higher reductions were obtained in melon (8.00 log cfu mL(-1)) followed by pear (2.10 log cfu mL(-1)) after 8 days of storage. L. monocytogenes in apple juice was unaffected by phage treatment in which the phage decreased to almost undetectable numbers. These results highlight that Listex P100 could avoid pathogen growth on fresh-cut and in fruit juices with high pH during storage at 10 °C. The combination with other technologies may be required to improve the phage application on high acidity fruits.

Characterization of peptide aptamers targeting Bfl-1 anti-apoptotic protein.

Bfl-1, an anti-apoptotic protein of the Bcl-2 family, has been identified as a potential therapeutic target for B-cell malignancies. We describe herein the first characterization of peptide aptamers selected against Bfl-1. We show that most of the Bfl-1 peptide aptamers do not interact with Bcl-2, Bcl-xL, or Mcl-1 in yeast and that some of them restore the pro-apoptotic activity of Bax in yeast in which Bax and Bfl-1 proteins are coexpressed. When expressed in mammalian cells, peptide aptamers interact with Bfl-1 and sensitize B-cell lines to apoptosis induced by chemotherapeutic agents. We further demonstrate that a nonconstrained peptide derived from one aptamer variable region reverses Bfl-1 anti-apoptotic activity in HeLa cells through disruption of Bax-Bfl-1 interaction. This peptide also promotes cell death in lymphoma B-cell lines expressing a high level of Bfl-1 and sensitizes these cells to drug-induced apoptosis. Taken together, these results further validate Bfl-1 as a therapeutic target for malignant B-cells and suggest that peptide aptamers may be a useful tool for guiding the identification of small compounds that target the anti-apoptotic Bfl-1 protein.

Inhibition of heat shock protein 27 (HspB1) tumorigenic functions by peptide aptamers.

Human heat shock protein 27 (Hsp27, HspB1) is an anti-apoptotic protein characterized for its tumorigenic and metastatic properties, and now referenced as a major therapeutic target in many types of cancer. Hsp27 biochemical properties rely on a structural oligomeric and dynamic organization. Downregulation by small interfering RNA or inhibition with dominant-negative mutant have proven their efficiency to counteract the anti-apoptotic and protective properties of Hsp27. In this study, we report the isolation and characterization of Hsp27-targeted molecules interfering with its structural organization. Using the peptide aptamer (PA) strategy, we isolated PAs that specifically interact with Hsp27 and not with the other members of the small heat shock protein family. In mammalian cell cultures, PAs expression perturbed the dimerization and oligomerization of Hsp27, and acted as negative regulators of the anti-apoptotic and cytoprotective activities of this protein. Further studies analyzing SQ20B cell xenografts in immunocompromised mice showed that PAs strongly reduced tumor development through cell cycle arrest. Our data suggest that PAs could provide a potential tool to develop strategies for the discovery of Hsp27 chemical inhibitors.

Modulation of Nr-13 antideath activity by peptide aptamers.

Tumor cells are characterized by deregulated proliferation and resistance to proapoptotic stimuli. The Bcl-2 family of antiapoptotic proteins is overexpressed in a large number of chemoresistant tumors. Downregulation or inhibition of antiapoptotic proteins might result in the sensitization of cancer cells to chemotherapeutic agents. In the present study, we took advantage of the peptide aptamer strategy to target Nr-13, a Bcl-2 antiapoptotic protein involved in neoplastic transformation by the Rous sarcoma virus. We isolated peptide aptamers that behave as Nr-13 regulators, in vitro and in mammalian cells in culture. Some of these aptamers have potential proapoptotic activities. These data suggest that peptide aptamers targeting the Bcl-2 family of apoptosis inhibitors may be useful for the development of anticancer molecules.

p53-dependent inhibition of mammalian cell survival by a genetically selected peptide aptamer that targets the regulatory subunit of protein kinase CK2.

Based on the perturbation of its expression in human cancers and on its involvement in transformation and tumorigenesis, protein kinase CK2 has recently attracted attention as a potential therapeutic target. To assess the value of CK2 as a target for antiproliferative strategies, we have initiated a program aiming to develop inhibitors targeting specifically the regulatory CK2beta subunit. Here, we use a two-hybrid approach to isolate from combinatorial libraries, peptide aptamers that specifically interact with CK2beta. One of these (P1), which has significant sequence homology to the cytomegalovirus IE2 protein, binds with high affinity to the N-terminal domain of CK2beta without disrupting the formation of the CK2 holoenzyme. Expression of green fluorescent protein (GFP)-P1 in different mammalian cell lines activates p53 phosphorylation on serine 15, induces an upregulation of p21 and the release of the Cyt-C and apoptosis-inducing factor proapoptotic proteins triggering caspase-dependent and caspase-independent apoptosis. GFP-P1-induced apoptosis is associated with a p53-dependent pathway as cell death was abrogated in p53 knocked out cells. In summary, our data show that genetically selected peptide aptamers that specifically target CK2beta can induce apoptosis in mammalian cells through the recruitment of a p53-dependent apoptosis pathway. They also emphasize the critical role of CK2beta for cell survival and might allow the design of novel proapoptotic agents targeting this protein.

Combinatorial protein reagents to manipulate protein function.

The design and use of combinatorial protein libraries has become a fast moving field in molecular biology. Different experimental systems supporting various selection schemes are now available. The latest breakthroughs include evolutionary experiments to improve existing binding surfaces, selections of homodimerizing peptides, the use of peptide aptamers to disrupt protein interactions inside living cells, and functional selections of aptamers to probe regulatory networks.

Targeted modification and transportation of cellular proteins.

Peptide aptamers are proteins selected from combinatorial libraries that display conformationally constrained variable regions. Peptide aptamers can disrupt specific protein interactions and thus represent a useful method for manipulating protein function in vivo. Here, we describe aptamer derivatives that extend the range of functional manipulations. We isolated an aptamer with increased affinity for its Cdk2 target by mutagenizing an existing aptamer and identifying tighter binding mutants with calibrated two-hybrid reporter genes. We used this and other anti-Cdk2 aptamers as recognition domains in chimeric proteins that contained other functional moieties. Aptamers fused to the catalytic domain of a ubiquitin ligase specifically decorated LexA-Cdk2 with ubiquitin moieties in vivo. Aptamers against Cdk2 and another protein, Ste5, that carried a nuclear localization sequence transported their targets into the nucleus. These experiments indicate that fusion proteins containing aptameric recognition moieties will be useful for specific modification of protein function in vivo.

Meiotic maturation in mollusc oocytes.

Molluscs, annelids and other lower invertebrates belonging to the protostome group exhibit special features in their ionic regulation of meiotic maturation and in their molecular control of metaphase arrest. These oocytes proceed from prophase I upon fertilization or hormonal stimulation and then either complete meiotic maturation or secondarily arrest in metaphase I until fertilization. We review here the recent progress on identifying the initial trigger in prophase I-arrested oocytes, emphasizing the crucial role of an early Ca2+ influx through specific Ca2+ channels. Metaphase I arrest, a unique feature of protostome animals, appears to rely on a subtle equilibrium between protein synthesis rate and destruction of regulating proteins. Some well-known components of MPF (M-phase-promoting factor) play their regular roles in protostome animals, albeit in a different environment which has not been fully characterized yet.

An artificial cell-cycle inhibitor isolated from a combinatorial library.

Understanding the genetic networks that operate inside cells will require the dissection of interactions among network members. Here we describe a peptide aptamer isolated from a combinatorial library that distinguishes among such interactions. This aptamer binds to cyclin-dependent kinase 2 (Cdk2) and inhibits its kinase activity. In contrast to naturally occurring inhibitors, such as p21(Cip1), which inhibit the activity of Cdk2 on all its substrates, inhibition by pep8 has distinct substrate specificity. We show that the aptamer binds to Cdk2 at or near its active site and that its mode of inhibition is competitive. Expression of pep8 in human cells retards their progression through the G1 phase of the cell cycle. Our results suggest that the aptamer inhibits cell-cycle progression by blocking the activity of Cdk2 on substrates needed for the G1-to-S transition. This work demonstrates the feasibility of selection of artificial proteins to perform functions not developed during evolution. The ability to select proteins that block interactions between a gene product and some partners but not others should make sophisticated genetic manipulations possible in human cells and other currently intractable systems.

The impact of two-hybrid and related methods on biotechnology.

Two-hybrid technology has contributed significantly to the unraveling of molecular regulatory networks by facilitating the discovery of protein interactions. Outgrowths of these methods are developing rapidly, including interaction mating to identify false positives and map protein networks, two-bait systems, systems not based on transcription, and systems permitting the selection of peptide aptamers to manipulate gene and allele function. These advances promise to have a significant impact on industrial biotechnology and drug development.

Genetic selection of peptide aptamers that recognize and inhibit cyclin-dependent kinase 2.

A network of interacting proteins controls the activity of cyclin-dependent kinase 2 (Cdk2) (refs 1,2) and governs the entry of higher eukaryotic cells into S phase. Analysis of this and other genetic regulatory networks would be facilitated by intracellular reagents that recognize specific targets and inhibit specific network connections. We report here the expression of a combinatorial library of constrained 20-residue peptides displayed by the active-site loop of Escherichia coli thioredoxin, and the use of a two-hybrid system to select those that bind human Cdk2. These peptide aptamers were designed to mimic the recognition function of the complementarity-determining regions of immunoglobulins. The aptamers recognized different epitopes on the Cdk2 surface with equilibrium dissociation constant in the nanomolar range; those tested inhibited Cdk2 activity. Our results show that peptide aptamers bear some analogies with monoclonal antibodies, with the advantages that they are isolated together with their coding genes, that their small size should allow their structures to be solved, and that they are designated to function inside cells.

The oocyte metaphase arrest.

Usually, oocyte meiosis reinitiation appears as a two step process during which release from the prophase block is followed by a second arrest in metaphase I or II. In this review, we will examine the mechanisms required to maintain the metaphase arrest and stabilize MPF activity at this stage. Then, we will analyse the processes required to exit from the metaphase block. These may drive the cells forward to the metaphase-anaphase transition, as a result of fertilization, activation or protein synthesis inhibition. Instead, inhibiting protein phosphorylation drives the oocyte back to interphase. All these treatments result in derepression of DNA synthesis.

[VLA and alpha6, beta4 integrins. Expression in normal and neoplastic human tissues]. / Les integrines VLA et alpha6beta4 expression sur les tissus humains normaux et neoplasiques.

Among the cellular adhesion molecules, the integrin family, more particularly the VLA (Very late antigen) integrins, is currently the subject of numerous investigations in pathology. These integrins are involved in cell-cell contact or cell-matrix adhesions. During neoplastic diseases, cellular expression of integrins changes and a study of the modifications could allow a new etiopathogenic approach carcinogenesis and metastatic phenomena. New prognostic factors may be defined in tumor pathology. We describe the general structure of integrins and the mechanisms of their binding with matricial ligands and with cytoskeleton. The expression of VLA integrins and the alpha6beta4 heterodimer on normal and neoplastic human tissues is then described. Finally, we describe the involvement of these proteins in tumor progression and tissue invasion.

Microinjection of suc1 transcripts delays the cell cycle clock in Patella vulgata embryos.

The suc1 protein is a cell cycle regulator whose precise function remains to be elucidated. The suc1 cDNA of the mollusk Patella vulgata was cloned and sequenced. It encodes a 9 kD protein showing a strong similarity with its human counterparts and to a lesser extend with its yeast counterparts. The expression of suc1 in maturing oocytes was shown to be tightly cell cycle-regulated. The abundance of the suc1 transcripts is high in prophase- and metaphase-arrested oocytes but drops dramatically upon exit from M-phase, after fertilization. The microinjection of suc1 synthetic messengers into embryonic blastomeres delayed the cell cycle clock, thus disrupting the perfect cell cycle synchrony exhibited by the blastomeres of early Patella embryos. Interestingly, this suc1 delaying effect was significantly reversed when cyclin B messengers were co-injected with suc1 messengers. These results show that Patella embryos offer a quite valuable model to study cell cycle regulation. Moreover, they support the existence of a negative control exerted by suc1 on the cell cycle traverse in a higher eukaryote.

Protein synthesis controls cyclin stability in metaphase I-arrested oocytes of Patella vulgata.

The metaphasic block of Patella vulgata oocytes depends on protein synthesis as an emetine treatment triggers metaphase/anaphase transition and leads to the sequential disappearance of cyclin A and B. Both cyclins are stable in metaphase-arrested oocytes which indicates that inhibition of protein synthesis activates cyclin proteolysis. The use of extracts prepared from metaphase-arrested oocytes and from emetine-treated oocytes fully confirms these in vivo findings. Considering previous observations about the regulation of protein synthesis throughout the cell cycle, we propose the involvement of a transient inhibition of translation in the activation of cyclin proteolysis and in exit from the M-phase arrest.