Anteroposterior patterning in the limb and digit specification: contribution of mouse genetics.

The limb has been a privileged object of investigation and reflection for scientists over the past two centuries and continues to provide a heuristic framework to analyze vertebrate development. Recently, accumulation of new data has significantly changed our view on the mechanisms of limb patterning, in particular along the anterior-posterior axis. These data have led us to revisit the mode of action of the zone of polarizing activity. They shed light on the molecular and cellular mechanisms of patterning linked to the Shh-Gli3 signaling pathway and give insights into the mechanism of activation of these cardinal factors, as well as the consequences of their activity. These new data are in good part the result of systematic Application of tools used in contemporary mouse molecular genetics. These have extended the power of mouse genetics by introducing mutational strategies that allow fine-tuned modulation of gene expression, interchromosomal deletions and duplication. They have even made the mouse embryo amenable to cell lineage analysis that used to be the realm of chick embryos. In this review, we focus on the data acquired over the last five years from the analysis of mouse limb development and discuss new perspectives opened by these results.     

Melatonin secretion in the Mashona mole-rat, Cryptomys darlingi--influence of light on rhythmicity

The hormone melatonin is synthesised and secreted from the pineal gland in darkness and triggers the daily and seasonal timing of various physiological and behavioural processes. The Mashona mole-rat, Cryptomys darlingi, lives in subterranean burrows that are completely sealed and is therefore rarely, if ever, exposed to light under natural conditions. Hence, this species is of particular interest for studies on rhythms of melatonin secretion. We investigated how plasma melatonin concentrations of the Mashona mole-rat responded to exposure to a long-term standard photoperiod of 12 h light, 12 h dark (12:12 LD), constant light (LL) and constant dark (DD). In addition, we examined whether plasma melatonin concentration was coupled to locomotor activity. Mashona mole-rats displayed rhythms of plasma melatonin concentration that appeared entrained to the standard LD photoperiod, suggesting that the mole-rat is capable of perceiving and entraining to this photic zeitgeber. Furthermore, under chronic constant lighting conditions (DD, LL), circadian rhythms in plasma melatonin concentration were observed, suggesting the possible existence of an endogenous rhythm. Light suppressed melatonin secretion, but constant light did not abolish the rhythm of plasma melatonin concentration. Between active and non-active animals, no difference in plasma melatonin concentration was found for any of the sequential photoperiods (LD1 DD, LD2, LL), tentatively suggesting that the rhythm of melatonin secretion is uncoupled from that of locomotor activity.     

Kinetics of decline of maternal measles virus-neutralizing antibodies in sera of infants in France in 2006

The optimal age for measles vaccination is an important health issue, since maternal antibodies may neutralize the vaccine antigen before a specific immune response develops, while delaying vaccination may increase the risk of complicated diseases in infants. However, measles vaccination impacts the duration of protection afforded by transplacental transfer of maternal antibodies: vaccination-induced maternal antibodies disappear faster than disease-induced antibodies. In order to maintain protection against measles in infants, it is important to monitor the dynamics of this phenomenon in vaccinated populations. To assess the current situation in France, a multicenter, prospective seroepidemiological study was conducted in seven French hospitals between October 2005 and January 2007. Maternal measles antibody concentrations from 348 infants 0 to 15 months old were measured using the plaque reduction neutralization assay. Geometric mean concentrations and the percentage of infants with maternal measles antibody concentrations above the protection threshold (≥120 mIU/ml) were assessed according to age. Results show that after more than 20 years of routine measles vaccination in France, maternal measles-neutralizing antibodies decrease dramatically in French infants by 6 months of age, from 1,740 mIU/ml for infants 0 to 1 month old to 223 mIU/ml for infants 5 to 6 months old, and that 90% of infants are not protected against measles after 6 months of age. Infant protection against measles could be optimized both by increasing herd immunity through an increased vaccine coverage and by lowering the age of routine vaccination from 12 to 9 months.     

Hypoglycemic and hypolipidemic effects of <Emphasis Type="Italic">Bersama engleriana</Emphasis> leaves in nicotinamide/streptozotocin-induced type 2 diabetic rats

Background

The present investigation was aimed at evaluating the hypoglycemic and hypolipidemic properties of the aqueous and methanolic extracts from Bersama engleriana leaves in streptozotocin/nicotinamide (STZ-NA)-induced type 2 diabetic rats.

Methods

Animals were orally treated for 4 consecutive weeks with Bersama engleriana extracts at doses of 300 or 600 mg/kg. The anti-diabetic effect was examined by measuring blood glucose (BG) at 0, 1, 14 and 28 days after STZ-NA treatment and, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG) levels at sacrifice (day 29). Glibenclamide (0.25 mg/kg) was used for comparison.

Results

STZ-NA-induced diabetic rats showed moderate to significant increases in the levels of BG, TG, TC, LDL-C while body weight, HDL-C levels and relative weights of liver and pancreas were decreased compared to controls (non diabetic rats). Administration of the plant extracts to STZ-NA diabetic rats resulted in a significant decrease in BG, TG, TC and LDL-C and the dose 600 mg/kg of the methanolic extract was the most effective; HDL-C level was markedly increased after four weeks compared to untreated diabetic rats. A dose-dependent increase in the relative weights of the diabetogenic organs was observed in the Bersama engleriana groups. It can be also noticed that the methanolic extract, especially the dose 600 mg/kg (p<0.001), produced more effects than glibenclamide and aqueous extract. Rats treated with glibenclamide (0.25 mg/kg) generally gave lower results compared to groups treated with plant extracts.

Conclusion

Results of the present study showed that Bersama engleriana extracts and especially its methanolic extract possess antidiabetogenic properties and beneficial effects on diabetic hyperlipidemia. All these effects could be due to the bioactive components revealed in the Bersama engleriana extracts such as triterpenes and phenols and which could justify its ethnomedical use.

     

<Emphasis Type="Italic">Helicobacter bilis</Emphasis>-Associated Suppurative Cholangitis in a Patient with X-Linked Agammaglobulinemia

?

Helicobacter bilis is a commensal bacterium causing chronic hepatitis and colitis in mice. In humans, enterohepatic Helicobacter spp. are associated with chronic hepatobiliary diseases.

Purpose

We aimed at understanding the microbial etiology in a patient with X-linked agammaglobulinemia presenting with suppurative cholangitis.

Methods

16S rDNA PCR directly performed on a liver biopsy retrieved DNA of H. bilis.

Results

Clinical outcome resulted in the normalization of clinical and biological parameters under antibiotic treatment by a combination of ceftriaxone, metronidazole, and doxycyclin followed by a 2-week treatment with moxifloxacin and a 2-month treatment with azithromycin.

Conclusion

In conclusion, these data suggest a specific clinical and microbiological approach in patients with humoral deficiency in order to detect H. bilis hepatobiliary diseases.

     

Testing and improving experimental parameters for the use of low molecular weight targets in array-CGH experiments

Array-comparative genomic hybridization (CGH) has evolved as a useful technique for the detection and characterization of deletions, and, to a lesser extent, of duplications. The resolution of the technique is dictated by the genomic distance between targets spotted on the microarray, and by the targets' sizes. The use of region-specific, high-resolution microarrays is a specific goal when studying regions that are prone to rearrangements, such as those involved in deletion syndromes. The aim of the present study was to evaluate the best experimental conditions to be used for array-CGH analysis using low molecular weight (LMW) targets. The parameters tested were: the target concentration, the way LMW targets are prepared (either as linearized plasmids or as purified PCR products), and the way the targets are attached to the array-CGH slide (in a random fashion on amino-silane coated slides, or by one amino-modified end on epoxysilane-coated slides). As a test case, we constructed a microarray harboring LMW targets located in the CREBBP gene, mutations of which cause the Rubinstein-Taybi syndrome (RTS). From 10 to 15% of RTS patients have a CREBBP deletion. We showed that aminosilane- and epoxysilane-coated slides were equally efficient with targets above 1,000 bp in size. On the other hand, with the smallest targets, especially those below 500 bp, epoxysilane-coated slides were superior to aminosilane-coated slides, which did not allow deletion detection. Use of the high resolution array allowed us to map intragenic breakpoints with precision and to identify a very small deletion and a duplication that were not detected by the currently available techniques for finding CREBBP deletions.     

Detection of 95 novel mutations in coagulation factor VIII gene F8 responsible for hemophilia A: results from a single institution

Hemophilia A (HA) is an X‐linked hereditary bleeding disorder defined by a qualitative and/or quantitative factor VIII (FVIII) deficiency. The molecular diagnosis of HA is challenging because of the high number of different causative mutations that are distributed throughout the large F8 gene. The putative role of the novel mutations, especially missense mutations, may be difficult to interpret as causing HA. We identified 95 novel mutations out of 180 different mutations responsible for HA in 515 patients from 406 unrelated families followed up at a single hemophilia treatment center of the Bicêtre university hospital (Assistance Publique‐Hôpitaux de Paris [AP‐HP], Le Kremlin‐Bicêtre). These 95 novel mutations comprised 55 missense mutations, 12 nonsense mutations, 11 splice site mutations, and 17 small insertions/deletions. We therefore developed a mutation analysis based on a body of proof that combines the familial segregation of the mutation, the resulting biological and clinical HA phenotype, and the molecular consequences of the amino acid (AA) substitution. For the latter, we studied the putative biochemical modifications: its conservation status with cross‐species FVIII and homologous proteins, its putative location in known FVIII functional regions, and its spatial position in the available FVIII 3D structures. The usefulness of such a strategy in interpreting the causality of novel F8 mutations is emphasized. Hum Mutat 27(7), 676–685, 2006. © 2006 Wiley‐Liss, Inc.     

Acinar cystic transformation of the pancreas (or acinar cell cystadenoma), a rare and recently described entity

We report a case of cystic acinar transformation (also known as acinar cell cystadenoma) of the pancreas. A 40-year old woman presented 3 episodes of acute pancreatitis that revealed a multicystic lesion of the ventral part of the head of the pancreas. A Whipple resection was performed. Gross examination of the specimen revealed a well-demarcated multiloculated cyst measuring 4 x 2 cm without communication with the excretory ducts. The cystic spaces contained a non-mucinous fluid. Histological analysis showed numerous various sized cysts that seemed to develop from microcystic structures in the surrounding acinar tissue. The cysts were lined by normal appearing acinar cells, with no atypia, sometimes flattened. Acinar cystic transformation is a rare lesion of the pancreas whose histogenesis is unknown. It should be distinguished from other lesions such as IPMT in order to discuss a surveillance strategy instead of surgical procedure.