Melatonin affects nuclear orphan receptors mRNA in the rat suprachiasmatic nuclei

The pineal hormone melatonin nocturnal synthesis feeds back on the suprachiasmatic nuclei (SCN), the central circadian clock. Indeed, daily melatonin injections in free-running rats resynchronize their locomotor activity to 24 h. However, the molecular mechanisms underlying this chronobiotic effect of the hormone are poorly understood. The endogenous circadian machinery involves positive and negative transcriptional feedback loops implicating different genes (particularly period (Per) 1-3, Clock, Bmal1, cryptochrome (Cry) 1-2). While CLOCK:BMAL1 heterodimer activates the rhythmic transcription of per and cry genes, the PER and CRY proteins inhibit the CLOCK:BMAL1 complex. In previous studies, we observed that the immediate resetting effect of a melatonin injection at the end of the subjective day on the SCN circadian activity did not directly involve the above-mentioned clock genes. Recently, nuclear orphan receptors (NORs) have been presented as functional links between the regulatory loops of the molecular clock. These NORs bind to a retinoic acid receptor-related orphan receptor response element (RORE) domain and activate (RORalpha) or repress (REV-ERBalpha) bmal1 expression. In this study, we investigated whether melatonin exerts its chronobiotic effects through transcriptional regulation of these transcription factors. We monitored roralpha, rorbeta and rev-erbalpha messenger RNA (mRNA) expression levels by quantitative in situ hybridization, up to 36 h following a melatonin injection at circadian time (CT) 11.5. Results clearly showed that, while roralpha was not affected by melatonin, the hormone partially prevented the decrease of the rorbeta mRNA expression observed in control animals during the first hours following the injection. The major result is that the rev-erbalpha mRNA expression rhythm was 1.3+/-0.8-h phase-advanced in melatonin-treated animals during the first subjective night following the melatonin administration. Moreover, the bmal1 mRNA expression was 1.9+/-0.9-h phase-shifted in the second subjective night following the melatonin injection. These results clearly suggest that the NOR genes could be the link between the chronobiotic action of melatonin and the core of the molecular circadian clock.

Review of solutions for 3D hydrodynamic modeling applied to aquaculture in South Pacific atoll lagoons

A workshop organized in French Polynesia in November 2004 allowed reviewing the current methods to model the three-dimensional hydrodynamic circulation in semi-enclosed atoll lagoons for aquaculture applications. Mollusk (e.g. pearl oyster, clam) aquaculture is a major source of income for South Pacific countries such as French Polynesia or Cook Islands. This aquaculture now requires a better understanding of circulation patterns to improve the spatial use of the lagoons, especially to define the best area to set larvae collectors. The pelagic larval duration of the relevant species (<20 days) and the size of the semi-closed lagoons (few hundreds of km2) drive the specifications of the model in terms of the spatial and temporal scale. It is considered that, in contrast with fish, mollusk larvae movements are limited and that their cycle occurs completely in the lagoon, without an oceanic stage. Atolls where aquaculture is productive are generally well-bounded, or semi-closed, without significant large and deep openings to the ocean. Nevertheless part of the lagoon circulation is driven by oceanic water inputs through the rim, ocean swells, tides and winds. Therefore, boundary conditions of the lagoon system are defined by the spatial structure of a very shallow rim (exposition and number of hoas), the deep ocean swell climate, tides and wind regimes. To obtain a realistic 3D numerical model of lagoon circulation with adequate forcing, it is thus necessary to connect in an interdisciplinary way a variety of methods (models, remote sensing and in situ data collection) to accurately represent the different components of the lagoon system and its specific boundary conditions. We review here the current methods and tools used to address these different components for a hypothetical atoll of the Tuamotu Archipelago (French Polynesia), representative of the semi-closed lagoons of the South Pacific Ocean. We hope this paper will serve as a guide for similar studies elsewhere and we provide guidelines in terms of costs for all the different stages involved.

[Pulmonary artery sarcoma during postpartum: CT findings]

We report the case of a 28 year-old female, who gave birth seven weeks previously, presenting with a pulmonary artery leiomyosarcoma discovered on a thoracic CT performed for clinical suspicion of pulmonary embolism. This case presents two major points of interest: on the first hand, it is a particular context (young post-partum patient), with classic symptoms of routine pulmonary embolism. On the other hand, the exam clearly demonstrates tumor enhancement, which is characteristic but rarely described.

La douleur biliaire : comment la reconnaître ? Comment l’explorer ?

Biliary colic is the most common clinical presentation of symptomatic gallstone disease, whatever its localisation (cholelithiasis or choledocolithiasis). The pain of biliary colic is unfortunately called "colic", a word suggesting paroxystic bouts and usually described as localised in the right upper quadrant. In fact, biliary pain is most frequently epigastric in location, usually starts abruptly to generally persists without fluctuation and resolve gradually over two to four hours. Biliary lithiasis has a high prevalence in the population, especially in elderly women but only 20% of the patients are symptomatic and among them, only 10 to 20% experience severe pain. Misdiagnosis is frequent with potential disastrous implications, especially with other causes of epigastric pain (atypical myocardial ischemia, perforated ulcer, etc.). Non invasive imaging of the biliary tract is now generally easy to obtain; abdominal ultrasound for gallbladder stones and magnetic resonance cholangiography for the main bile duct and the intrahepatic bile ducts. But, for gallbladder stones, the greatest care must be taken by the radiologist to link up the symptomatology and the cholelithiasis. Precise description of the abdominal pain (nature, intensity, location, duration, irradiation...) is needed and must be searched by the radiologist to prevent misdiagnosis.

Genetic Clines in the Bay of Biscay Provide Estimates of Migration for Sardina pilchardus

Nine allozymic loci in 1,635 individuals of Sardina pilchardus obtained at 33 sites ranging from the North to the South limits of the Bay of Biscay were analyzed to provide a description of the genetic structure of the sardine population. Individual body size and age were also recorded and analyzed. In the study population, weak but significant genetic differences were found, and a cline was observed between multilocus heterozygosity and longitude. The cline was predominantly driven by allelic frequencies of two loci, PGM-1* and PEP-lt*, and using a cline model, we estimated a migration rate of 103.1 km/gen (dispersal distance per generation). In addition, we observed that the cline was linked to biological data such as mean length and mean age of the fish. Two hypotheses may explain this cline: mixing of two different populations in the Bay of Biscay or a selective process. The weak genetic differences, the important dispersal distance per generation, and the link between genetic and biological data suggest that selection is likely to be the primary factor that maintains the cline.

Clinical evaluation of the use of the M2A patency capsule system before a capsule endoscopy procedure, in patients with known or suspected intestinal stenosis

BACKGROUND AND STUDY AIM

The main complication of video capsule endoscopy (VCE) is the blocking of the capsule by a gastrointestinal stenosis. The "patency capsule" is a self-dissolving capsule that is the same size as the video capsule. It contains a radiofrequency identification (RFID) tag that allows it to be detected by a scanning device placed on the abdominal wall. When its passage is blocked by a stenosis, the patency capsule dissolves in 40-80 hours after ingestion. The aim of this study was to evaluate the usefulness of this system in patients with suspected intestinal stenosis but also requiring VCE.

PATIENTS AND METHODS

22 patients (16 men; 46 +/- 18 years; 15 with diagnosed or suspected Crohn's disease, two with suspected intestinal tumor, and two on nonsteroidal anti-inflammatory drugs) were first investigated with an abdominal CT plus enteroclysis (entero-CT, n = 15) or a small-bowel follow-through (SBFT, n = 7). The patency capsule was then administered at around 09.00 to fasting patients. The presence of the patency capsule in the digestive tract was assessed 30 hours later using the hand-held scanner. When the patency capsule was detected, a plain abdominal film was obtained, and this was repeated every 24 hours until capsule expulsion.

RESULTS

At 30 hours after ingestion, the patency capsule was detected in 17 patients (72.3 %): in the area of the small intestine (n = 6) and in the colon (n = 11). In all the patients in whom the capsule was blocked in the small intestine, the stenosis had been suspected on CT or SBFT. In three patients, the delay in progression of the patency capsule led to cancellation of the VCE procedure. In three patients, the patency capsule induced a symptomatic intestinal occlusion, which resolved spontaneously in one and required emergency surgery in two. Although these two patients would have been obliged to undergo operation for their primary disease in any case, the procedure had to be brought forward. In one patient, the capsule passed through the stenosis without symptoms. All patients in whom the progression of the patency capsule was delayed had an established or suspected diagnosis of Crohn's disease.

CONCLUSIONS

The current technical development of the patency capsule limits its use in clinical practice, as it did not detect stenoses undiagnosed by CT or SBFT. The start of dissolution at 40 hours after ingestion is too slow to prevent episodes of intestinal occlusion. Patients with Crohn's disease are most likely to be at risk of blockage of progression of the capsule and should benefit from a CT investigation before VCE. However, a careful interview eliciting the patient's medical history and symptoms remains the most useful indicator with regard to suspicion of an intestinal stenosis.

Clinical evaluation of the use of the M2A patency capsule system before a capsule endoscopy procedure, in patients with known or suspected intestinal stenosis

BACKGROUND AND STUDY AIM

The main complication of video capsule endoscopy (VCE) is the blocking of the capsule by a gastrointestinal stenosis. The "patency capsule" is a self-dissolving capsule that is the same size as the video capsule. It contains a radiofrequency identification (RFID) tag that allows it to be detected by a scanning device placed on the abdominal wall. When its passage is blocked by a stenosis, the patency capsule dissolves in 40-80 hours after ingestion. The aim of this study was to evaluate the usefulness of this system in patients with suspected intestinal stenosis but also requiring VCE.

PATIENTS AND METHODS

22 patients (16 men; 46 +/- 18 years; 15 with diagnosed or suspected Crohn's disease, two with suspected intestinal tumor, and two on nonsteroidal anti-inflammatory drugs) were first investigated with an abdominal CT plus enteroclysis (entero-CT, n = 15) or a small-bowel follow-through (SBFT, n = 7). The patency capsule was then administered at around 09.00 to fasting patients. The presence of the patency capsule in the digestive tract was assessed 30 hours later using the hand-held scanner. When the patency capsule was detected, a plain abdominal film was obtained, and this was repeated every 24 hours until capsule expulsion.

RESULTS

At 30 hours after ingestion, the patency capsule was detected in 17 patients (72.3 %): in the area of the small intestine (n = 6) and in the colon (n = 11). In all the patients in whom the capsule was blocked in the small intestine, the stenosis had been suspected on CT or SBFT. In three patients, the delay in progression of the patency capsule led to cancellation of the VCE procedure. In three patients, the patency capsule induced a symptomatic intestinal occlusion, which resolved spontaneously in one and required emergency surgery in two. Although these two patients would have been obliged to undergo operation for their primary disease in any case, the procedure had to be brought forward. In one patient, the capsule passed through the stenosis without symptoms. All patients in whom the progression of the patency capsule was delayed had an established or suspected diagnosis of Crohn's disease.

CONCLUSIONS

The current technical development of the patency capsule limits its use in clinical practice, as it did not detect stenoses undiagnosed by CT or SBFT. The start of dissolution at 40 hours after ingestion is too slow to prevent episodes of intestinal occlusion. Patients with Crohn's disease are most likely to be at risk of blockage of progression of the capsule and should benefit from a CT investigation before VCE. However, a careful interview eliciting the patient's medical history and symptoms remains the most useful indicator with regard to suspicion of an intestinal stenosis.

Le kyste lympho-épithélial du pancréas : à propos d’un cas

Lymphoepithelial cyst is a rare benign dysembryoplastic lesion of the pancreas, difficult to diagnose before surgery. The authors report the case of a 44 year old man with low left sided chest pain. CT-scan described a multilocular cystic tumor of the tail of the pancreas. The patient underwent a distal pancreatectomy with splenectomy. Histologic analysis led to the diagnosis of lymphoepithelial cyst of the pancreas. Through this observation, the authors stress the value of imaging in this benign entity that must be considered when evaluating a cystic pancreatic lesion because a different therapeutic approach may be required.

Temporary intestinal occlusion induced by a "patency capsule" in a patient with Crohn's disease

A 26-year-old woman was admitted for the investigation of abdominal symptoms related to ileal Crohn's disease. The patient had been diagnosed 3 years previously with systemic sclerosis, and had been experiencing digestive complaints for 6 months. A first computed tomography (CT) scan showed ileal intestinal mucosal alterations, associated with a sclerolipomatosis and suspicion of ileal stenosis. An ileocolonoscopy was then performed and showed ulcers in the terminal ileum with nonspecific inflammatory changes found on biopsies, both suggesting the diagnosis of Crohn's disease. The patient was admitted for M2A capsule endoscopy, in order to clarify the respective roles of systemic sclerosis and Crohn's disease with regard to the symptoms and secondarily to determine the anatomical extent of the Crohn's lesions. A patency capsule was administered, for detection of intestinal stenosis before capsule endoscopy was done. At 30 hours after capsule ingestion, the patient complained of abdominal pain and nausea and experienced intestinal obstruction due to the blockage of the patency capsule in the ileal stenosis. The capsule dissolved after 76 hours and the patient then improved. After a few days, the patient underwent ileocecal resection. Pathological examination of the surgical specimen confirmed the presence of an ileal stenosis 17 cm in length. In some circumstances a patency capsule may dissolve slowly, leading to transitory intestinal obstruction requiring medical intervention. It should thus be used cautiously under clinical surveillance in patients with Crohn's disease.

La perspective d’une étude dynamique des artères des membres inférieurs en IRM grâce à la séquence ECTRICKS

PURPOSE

This article presents a new MR angiography technique, Elliptic Centric Time Resolved Imaging on Contrast KineticS (ECTRICKS), which allows dynamic evaluation of the lower limb arteries opacification when venous return prevents adequate diagnostic evaluation of calf arteries.

PATIENTS AND METHODS

Comparative examinations could be compared. Additional arteries in 59 patients using a standard MRA technique and the ECTRICKS technique.

RESULTS

A total of 33 examinations could be compared. Additional arteries could be evaluated in 10% of our patient population using the ECTRICKS technique, and in 20% for our diabetic population. Arterial evaluation was better with the ECTRICKS technique in patients with diabetes and venous insufficiency.

CONCLUSION

ECTRICKS is a good complementary sequence for evaluation the calf arteries in patients with diabetes or early venous return.

[The gallstone ileus: key points and traps of diagnosis with sliced pictures]

Twenty-five per cent of obstructions in patients 70 years and over could be caused by gallstone ileus. Due to the variable clinical symptomatology, diagnosis can be delayed and results in poorer outcome than expected for this benign pathology. Early CT evaluation improves the accuracy of diagnosis. Based on a review of twelve cases, the typical imaging features and pitfalls will be reviewed.

[Small bowel obstruction caused by enteroliths and Meckel's diverticulitis associated with internal paracecal hernia in an adult]

The Authors report a rare case of Meckel's diverticulum complicated by diverticulitis and a small bowel obstruction due to enteroliths, associated to a paracecal internal hernia. Computed tomography was useful for surgical planning.

Le péritoine « témoin » de la pathologie abdomino-pelvienne

Most inflammatory, infectious or tumoral diseases of the bowel and abdominal organs may secondarily involve the peritoneum which acts as a mirror of the diseases. Multidetector CT allows breathhold acquisitions through the abdomen and pelvis providing high spatial and contrast resolution imaging at all phases of contrast distribution as well as MPR and 3D capabilities.

The proprotein convertase PC2 is involved in the maturation of prosomatostatin to somatostatin-14 but not in the somatostatin deficit in Alzheimer's disease

A somatostatin deficit occurs in the cerebral cortex of Alzheimer's disease patients without a major loss in somatostatin-containing neurons. This deficit could be related to a reduction in the rate of proteolytic processing of peptide precursors. Since the two proprotein convertases (PC)1 and PC2 are responsible for the processing of neuropeptide precursors directed to the regulated secretory pathway, we examined whether they are involved first in the proteolytic processing of prosomatostatin in mouse and human brain and secondly in somatostatin defect associated with Alzheimer's disease. By size exclusion chromatography, the cleavage of prosomatostatin to somatostatin-14 is almost totally abolished in the cortex of PC2 null mice, while the proportions of prosomatostatin and somatostatin-28 are increased. By immunohistochemistry, PC1 and PC2 were localized in many neuronal elements in human frontal and temporal cortex. The convertases levels were quantified by Western blot, as well as the protein 7B2 which is required for the production of active PC2. No significant change in PC1 levels was observed in Alzheimer's disease. In contrast, a marked decrease in the ratio of the PC2 precursor to the total enzymatic pool was observed in the frontal cortex of Alzheimer patients. This decrease coincides with an increase in the binding protein 7B2. However, the content and enzymatic activity of the PC2 mature form were similar in Alzheimer patients and controls. Therefore, the cortical somatostatin defect is not due to convertase alteration occuring during Alzheimer's disease. Further studies will be needed to assess the mechanisms involved in somatostatin deficiency in Alzheimer's disease.

Subchronic phencyclidine treatment impairs performance of C57BL/6 mice in the attentional set-shifting task

Schizophrenic patients show deficits in their ability to shift attention to new stimuli during attentional set-shifting tasks. An equivalent task has been developed in rodents. This task was used to assess effects of phencyclidine (PCP), a drug widely used to model schizophrenia, in mice. Mice were administered PCP (0.63 or 1.3 mg/kg) daily, beginning 5 days prior to training and continuing throughout the test period. Mice were trained to discriminate stimuli to find a food reward in a series of discriminations. PCP increased the number of trials required to reach the criterion during simple and reversal discriminations, but not when the discriminations were repeated with a new set of stimuli (i.e. during the intradimensional shift and its reversal), suggesting an interaction between PCP effects and novelty. The 1.3 mg/kg of PCP also impaired performance of mice during the extradimensional shift. Similar results have been reported in schizophrenic patients. Although, in control mice, performance of the extradimensional shift was not impaired relative to the intradimensional shift, suggesting that the mouse may not be a suitable species for assessment in this model, specific discriminations within this task were sensitive to impairment by PCP, implying, therefore, that it may have some utility in modelling discrete aspects of schizophrenia in humans.