Endodermal/ectodermal interfaces during pharyngeal segmentation in vertebrates

A key event in the formation of the pharyngeal arches is the outpocketing of the endodermal pharyngeal pouches and the establishment of contact with the overlying ectoderm. However, relatively little is known about how the endoderm and ectoderm relate to each other at these points of contact and the extent to which this differs between the pouches. We have therefore detailed the interactions between the pharyngeal pouches and ectoderm in the chick embryo. Unlike the other pouches, the first pouch does not sustain direct contact with the ectoderm but separates after initial contact. Contrastingly, a perforation is formed between the second pouch and cleft that creates an external opening into the pharynx. Finally, the third and fourth pouch endoderm can be seen to bulge outwards through the ectoderm, although external openings to the pharyngeal lumen are not established. To understand whether these behaviours represent derived or ancestral features, we characterised the pharyngeal ectodermal–endodermal interfaces in the shark embryo. We found that the pouches of the posterior gill-bearing arches in this species also displayed the outward bulging of the endoderm into the ectoderm, although openings were established. We further used genetic tools to detail unambiguously the relationship between the endoderm and ectoderm in zebrafish and mouse embryos and again found that the posterior pouches break through the ectoderm. Thus different pharyngeal pouches establish different topological relationships with the overlying ectoderm and the posterior pouches initiate the developmental programme for the formation of gills, be they amniotes or anamniotes.     

Anandamide produced by Ca2+-insensitive enzymes induces excitation in primary sensory neurons

The endogenous lipid agent N-arachidonoylethanolamine (anandamide), among other effects, has been shown to be involved in nociceptive processing both in the central and peripheral nervous systems. Anandamide is thought to be synthesised by several enzymatic pathways both in a Ca²⁺-sensitive and Ca²⁺-insensitive manner, and rat primary sensory neurons produce anandamide. Here, we show for the first time, that cultured rat primary sensory neurons express at least four of the five known Ca²⁺-insensitive enzymes implicated in the synthesis of anandamide, and that application of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-arachidonoyl, the common substrate of the anandamide-synthesising pathways, results in anandamide production which is not changed by the removal of extracellular Ca²⁺. We also show that anandamide, which has been synthesised in primary sensory neurons following the application of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-arachidonoyl induces a transient receptor potential vanilloid type 1 ion channel-mediated excitatory effect that is not inhibited by concomitant activation of the cannabinoid type 1 receptor. Finally, we show that sub-populations of transient receptor potential vanilloid type 1 ion channel-expressing primary sensory neurons also express some of the putative Ca²⁺-insensitive anandamide-synthesising enzymes. Together, these findings indicate that anandamide synthesised by primary sensory neuron via a Ca²⁺-insensitive manner has an excitatory rather than an inhibitory role in primary sensory neurons and that excitation is mediated predominantly through autocrine signalling. Regulation of the activity of the Ca²⁺-insensitive anandamide-synthesising enzymes in these neurons may be capable of regulating the activity of these cells, with potential relevance to controlling nociceptive processing.     

Copy number variants in patients with short stature

Height is a highly heritable and classic polygenic trait. Recent genome-wide association studies (GWAS) have revealed that at least 180 genetic variants influence adult height. However, these variants explain only about 10% of the phenotypic variation in height. Genetic analysis of short individuals can lead to the discovery of novel rare gene defects with a large effect on growth. In an effort to identify novel genes associated with short stature, genome-wide analysis for copy number variants (CNVs), using single-nucleotide polymorphism arrays, in 162 patients (149 families) with short stature was performed. Segregation analysis was performed if possible, and genes in CNVs were compared with information from GWAS, gene expression in rodents'' growth plates and published information. CNVs were detected in 40 families. In six families, a known cause of short stature was found (SHOX deletion or duplication, IGF1R deletion), in two combined with a de novo potentially pathogenic CNV. Thirty-three families had one or more potentially pathogenic CNVs (n=40). In 24 of these families, segregation analysis could be performed, identifying three de novo CNVs and nine CNVs segregating with short stature. Four were located near loci associated with height in GWAS (ADAMTS17, TULP4, PRKG2/BMP3 and PAPPA). Besides six CNVs known to be causative for short stature, 40 CNVs with possible pathogenicity were identified. Segregation studies and bioinformatics analysis suggested various potential candidate genes.     

Microcephaly with or without chorioretinopathy,lymphoedema, or mental retardation (MCLMR): review of phenotype associated with KIF11 mutations

Microcephaly with or without chorioretinopathy, lymphoedema, or mental retardation (MCLMR) (MIM No.152950) is a rare autosomal dominant condition for which a causative gene has recently been identified. Mutations in the kinesin family member 11 (KIF11) gene have now been described in 16 families worldwide. This is a review of the condition based on the clinical features of 37 individuals from 22 families. This report includes nine previously unreported families and additional information for some of those reported previously. The condition arose de novo in 8/20 families (40%). The parental results were not available for two probands. The mutations were varied and include missense, nonsense, frameshift, and splice site and are distributed evenly throughout the KIF11 gene. In our cohort, 86% had microcephaly, 78% had an ocular abnormality consistent with the diagnosis, 46% had lymphoedema, 73% had mild-moderate learning difficulties, 8% had epilepsy, and 8% had a cardiac anomaly. We identified three individuals with KIF11 mutations but no clinical features of MCLMR demonstrating reduced penetrance. The variable expression of the phenotype and the presence of mildly affected individuals indicates that the prevalence may be higher than expected, and we would therefore recommend a low threshold for genetic testing.     

Replication of the effect of SLC2A9 genetic variation on serum uric acid levels in American Indians

Increased serum uric acid (SUA) or hyperuricemia, a risk factor for gout, renal and cardiovascular diseases, is caused by either increased production or decreased excretion of uric acid or a mix of both. The solute carrier protein 2 family, member 9 (SLC2A9) gene encodes a transporter that mediates urate flux across the renal proximal tubule. Genome-wide association studies have consistently shown the association of single-nucleotide polymorphisms in this gene with SUA in majority populations. American Indian participants of the Strong Heart Family Study, belonging to multigenerational families, have high prevalence of hyperuricemia. We conducted measured genotype analyses, based on variance components decomposition method and accounting for family relationships, to assess whether the association between SUA and SLC2A9 gene polymorphisms generalized to American Indians (n=3604) of this study. Seven polymorphisms were selected for genotyping based on their association with SUA levels in other populations. A strong association was found between SLC2A9 gene polymorphisms and SUA in all centers combined (P-values: 1.3 × 10⁻³¹–5.1 × 10⁻²³) and also when stratified by recruitment center; P-values: 1.2 × 10⁻¹⁴–1.0 × 10⁻⁵. These polymorphisms were also associated with the estimated glomerular filtration rate and serum creatinine but not albumin–creatinine ratio. In summary, the association of polymorphisms in the uric acid transporter gene with SUA levels extends to a new population of American Indians.     

Malignant gastric outlet obstruction: Which is the best therapeutic option?

Malignant gastric outlet obstruction(MGOO) is a clinical condition characterized by the mechanical obstruction of the pylorus or the duodenum due to tumor compression/infiltration, with consequent reduction or impossibility of an adequate oral intake. MGOO is mainly secondary to advanced pancreatic or gastric cancers, and significantly impacts on patients' survival and quality of life.Patients suffering from this condition often present with intractable vomiting and severe malnutrition, which further compromise therapeutic chances. Currently,palliative strategies are based primarily on surgical gastrojejunostomy and endoscopic enteral stenting with self-expanding metal stents. Several studies have shown that surgical approach has the advantage of a more durable relief of symptoms and the need of fewer re-interventions, at the cost of higher procedure-related risks and longer hospital stay. On the other hand, enteral stenting provides rapid clinical improvement, but have the limit of higher stent dysfunction rate due to tumor ingrowth and a subsequent need of frequent reinterventions. Recently, a third way has come from interventional endoscopic ultrasound, through the development of endoscopic ultrasound-guided gastroenterostomy technique with lumen-apposing metal stent. This new technique may ideally encompass the minimal invasiveness of an endoscopic procedure and the long-lasting effect of the surgical gastrojejunostomy, and brought encouraging results so far, even if prospective comparative trial are still lacking. In this Review, we described technical aspects and clinical outcomes of the above-cited therapeutic approaches, and discussed the open questions about the current management of MGOO.     

Bowel endometriosis: Colorectal surgeon’s perspective in a multidisciplinary surgical team

Endometriosis is a gynecological condition that presents as endometrial-like tissue outside the uterus and induces a chronic inflammatory reaction. Up to 15% of women in their reproductive period are affected by this condition. Deep endometriosis is defined as endometriosis located more than 5 mm beneath the peritoneal surface. This type of endometriosis is mostly found on the uterosacral ligaments, inside the rectovaginal septum or vagina, in the rectosigmoid area, ovarian fossa, pelvic peritoneum, ureters, and bladder, causing a distortion of the pelvic anatomy. The frequency of bowel endometriosis is unknown, but in cases of bowel infiltration, about 90% are localized on the sigmoid colon or the rectum. Colorectal involvement results in alterations of bowel habits such as constipation, diarrhea, tenesmus, dyschezia, and, rarely, rectal bleeding. Differential diagnosis must be made in case of irritable bowel syndrome, solitary rectal ulcer syndrome, and a rectal tumor. A precise diagnosis about the presence, location, and extent of endometriosis is necessary to plan surgical treatment. Multidisciplinary laparoscopic treatment has become the standard of care. Depending on the size of the lesion and site of involvement, full-thickness disc excision or bowel resection needs to be performed by an experienced colorectal surgeon. Long-term outcomes, following bowel resection for severe endometriosis, regarding pain and recurrence rate are good with a pregnancy rate of 50%.     

Caecal pH is a biomarker of excessive colonic fermentation

AIM:To ascertain whether caecal pH is different in patients with irritable bowel syndrome(IBS),whose primary symptoms are bloating and distension,to healthy controls.METHODS:Motility and pH data were reviewed from16 patients with RomeⅢdefined IBS and 16 healthy controls,who had undergone a wireless motility capsule(WMC)study using a standardized protocol.Motility measures were anchored around known anatomical landmarks as identified by compartmental pH changes.Sixty-minute epochs were used to quantify antral,duodenal,ileal,caecal and distal colonic contractility.The maximum and minimum pH was measured either side of the ileo-caecal junction.RESULTS:No differences were seen in motility parameters,compartmental transit times or maximal ileal pH between the two groups.Caecal pH was significantly lower in patients compared to controls(5.12±0.05vs 6.16±0.15,P<0.0001).The ileal:caecalΔchange was greater in patients than controls(-2.63±0.08 vs-1.42±0.11,P<0.0001).There was a significant correlation between caecal pH and right colonic contractility(r=0.54,P=0.002).CONCLUSION:Patients with bloating and distension have a lower caecal pH compared to controls.The measurement of caecal pH using the WMC provides a quantifiable biomarker of fermentation potentially identifying those patients that may preferentially benefit from antibiotic or dietary interventions.     

Defluoridation efficiency of a green composite reactive material derived from lateritic soil and gastropod shell

In the bid to exploit the synergy in mixed metal matrix that enhances substrate binding affinity, a composite reactive material (GLT) was prepared using lateritic soil and Gastropod shell as precursors. The defluoridation efficiency of the GLT was studied in laboratory grade fluoride contaminated water and groundwater matrix. Using experimental evidences, insight into the underlying defluoridation mechanisms of GLT was provided. The monolayer adsorption capacity (q_m, mg/g) of the GLT (43.7 mg/g) was higher than that of any of the precursors (i.e. lateritic soil (q_{m =} 2.8 mg/g) and Gastropod shell (q_m = 19.8 mg/g)), which confirmed the synergistic effect of the constituents of the composite. Premised on the results of kinetic analysis, the Gibbs (?G) free energy value of formation of insoluble metal fluoride and the results of the evaluation of the effects of water chemistry on the fluoride removal efficiency of the GLT, mechanism of the defluoridation process was found to be a combination of adsorption (via ion exchange or outer sphere complexation) and precipitation reaction. Relative to the performance of the GLT in laboratory grade water, the GLT was also effective in groundwater but the value of the Langmuir monolayer adsorption capacity (q_m mg/g) was lower in the groundwater system (29.76 mg/g) than in the laboratory grade water system (43.7 mg/g). The leached constituents of the GLT enhanced the values of the pH, electrical conductivity and the total dissolved solids of the treated water.