Expression of neurexin ligands,the neuroligins and the neurexophilins,in the developing and adult rodent olfactory bulb

The neurexins are a large family of neuronal cell-surface proteins believed to be involved in intercellular signalling and the formation of intercellular junctions. To begin to assess the role of these proteins in the olfactory bulb, we describe here the expression patterns of their transmembrane and secreted ligands, the neuroligins and neurexophilins, during both embryonic and postnatal development. In situ hybridisation showed that neuroligin 1 and 2 were expressed by second order mitral cells during early postnatal development but not in adults. The secreted ligand for alpha-neurexin, neurexophilin 1, was also expressed in the postnatal olfactory bulb. Neurexophilin 1 was detected in only periglomerular cells during the early postnatal period of glomerular formation but later was also expressed in mitral cells. These results suggest that neurexin-ligand interactions may be important for development and/or maturation of synaptic connections in the primary olfactory pathway.     

A diabody that dissociates to monomer forms at low concentration: effects on binding activity and tumor targeting

A human scFv, 15-9, was selected from a phage display library for binding to murine laminin-1. A diabody was made from the scFv by shortening the linker from 15 to 5 amino acids between the VH and VL sequence. Radioiodinated scFv and diabody were analyzed for size, binding to laminin, and biodistribution in tumor bearing mice. Diabody preparations at concentrations greater than 10 nM were largely dimer forms (approximately 60 kDa) as judged by gel filtration, but diluted diabody was eluted as a monomer (approximately 30 kDa). At low concentrations the radiolabeled diabody did not bind well to laminin. The (125)I diabody had significantly lower accumulation in tumors than did the scFv when injected at lower concentrations. These data indicate that the diabody dimer dissociates at concentrations of about 10nM resulting in monomers with no binding activity for laminin and poor tumor homing properties.     

Insulin resistance in adolescents with Down syndrome: a cross-sectional study

Background

The prevalence of diabetes mellitus is higher in individuals with Down syndrome (DS) than in the general population; it may be due to the high prevalence of obesity presented by many of them. The aim of this study was to evaluate the insulin resistance (IR) using the HOMA (Homeostasis Model Assessment) method, in DS adolescents, describing it according to the sex, body mass index (BMI) and pubertal development.

Methods

15 adolescents with DS (8 males and 7 females) were studied, aged 10 to 18 years, without history of disease or use of medication that could change the suggested laboratory evaluation. On physical examination, the pubertal signs, acanthosis nigricans (AN), weight and height were evaluated. Fasting plasma glucose and insulin were analysed by the colorimetric method and RIA-kit LINCO, respectively. IR was calculated using the HOMA method. The patients were grouped into obese, overweight and normal, according to their BMI percentiles. The EPIINFO 2004 software was used to calculate the BMI, its percentile and Z score.

Results

Five patients were adults (Tanner V or presence of menarche), 9 pubertal (Tanner II – IV) and 1 prepubertal (Tanner I). No one had AN. Two were obese, 4 overweight and 9 normal. Considering the total number of patients, HOMA was 1.7 ± 1.0, insulin 9.3 ± 4.8 μU/ml and glucose 74.4 ± 14.8 mg/dl. The HOMA values were 2.0 ± 1.0 in females and 1.5 ± 1.0 in males. Considering the nutritional classification, the values of HOMA and insulin were: HOMA: 3.3 ± 0.6, 2.0 ± 1.1 and 1.3 ± 0.6, and insulin: 18.15 ± 1.6 μU/ml, 10.3 ± 3.5 μU/ml and 6.8 ± 2.8 μU/ml, in the obese, overweight and normal groups respectively. Considering puberty, the values of HOMA and insulin were: HOMA: 2.5 ± 1.3, 1.4 ± 0.6 and 0.8 ± 0.0, and insulin: 13.0 ± 5.8 μU/ml, 7.8 ± 2.9 μU/ml and 4.0 ± 0.0 μU/ml, in the adult, pubertal and prepubertal groups respectively.

Conclusion

The obese and overweight, female and adult patients showed the highest values of HOMA and insulin.     

Development of the submucous plexus in the large intestine of the mouse

In the small intestine of both embryonic birds and mammals, neuron precursors aggregrate first at the site of the myenteric plexus, and the submucous plexus develops later. However, in the large intestine of birds, the submucosal region is colonised by neural-crest-derived cells before the myenteric region (Burns and Le Douarin, Development 125:4335-4347, 1998). Using antisera that recognize undifferentiated neural-crest-derived cells (p75NTR) and differentiated neurons (PGP9.5), we examined the colonisation of the murine large intestine by neural-crest-derived cells and the development of the myenteric and submucosal plexuses. At E12.5, when the neural crest cells were migrating through and colonising the hindgut, the hindgut mesenchyme was largely undifferentiated, and a circular muscle layer could not be discerned. Neural-crest-derived cells migrated through, and settled in, the outer half of the mesenchyme. By E14.5, neural-crest-derived cells had colonised the entire hindgut; at this stage the circular muscle layer had started to differentiate. From E14.5 to E16.5, p75NTR- and PGP9.5-positive cells were observed on the serosal side of the circular muscle, in the myenteric region, but not in the submucosal region. Scattered, single neurons were first observed in the submucosal region around E18.5, and groups of neurons forming ganglia were not observed until after birth. The development of the enteric plexuses in the murine large intestine therefore differs from that in the avian large intestine.     

The autoradiographic localization of zinc within the pancreatic islets of the rainbow trout,Salmo gairdneri

Summary This experiment reports on the localization of zinc within the pancreatic islets of Salmo gairdneri. Individual fish were injected with ⁶⁵Zn and the distribution of the isotope within the islets was determined by autoradiography. Insulin cells were found to accumulate approximately twice as much zinc per unit area as the rest of the islet tissue. It is presumed that this zinc is involved with the crystallization and storage of insulin within the insulin cells. Various histological methods were investigated to ascertain the procedure which best precipitated zinc and at the same time avoided excess leaching.     

An electrophoretic analysis of the Etheostoma variatum complex (Percidae: Etheostomatini), with associated zoogeographic considerations

Synopsis The Etheostoma variatum complex is comprised of five species (E. euzonum, E. kanawhae, E. osburni, E. tetrazonum, E. variatum) distributed from the Allegheny River, New York, to the White River, Arkansas. Electrophoretic data provide evidence of a division of the complex into two geographic units: E. variatum, E. kanawhae, and E. osburni in the Appalachian region, and E. euzonum and E. tetrazonum in the Ozarks. Genic variation exists also between the Sac and Big river populations of E. tetrazonum. Genic variation and present faunal distributions suggest that an ancestral stock was widely distributed in Teays and Old Mississippi rivers but separated by a Pleistocene ice advance. Some populations survived in an Ozarkian refugium, while more eastern populations, such as the precursor to E. variatum, may have evolved in a southern refuge of the developing Ohio River. The Teays (New) River gorge, including Kanawha Falls, has prevented E. variatum from invading territory occupied by E. osburni and E. kanawhae.     

Expression and function of cell adhesion molecules during neural crest migration

Neural crest cells are highly migratory cells that give rise to many derivatives including peripheral ganglia, craniofacial structures and melanocytes. Neural crest cells migrate along defined pathways to their target sites, interacting with each other and their environment as they migrate. Cell adhesion molecules are critical during this process. In this review we discuss the expression and function of cell adhesion molecules during the process of neural crest migration, in particular cadherins, integrins, members of the immunoglobulin superfamily of cell adhesion molecules, and the proteolytic enzymes that cleave these cell adhesion molecules. The expression and function of these cell adhesion molecules and proteases are compared across neural crest emigrating from different axial levels, and across different species of vertebrates.