Effect of hydrostatic pressure on ADH induced osmotic water flow in toad bladder

The effect of hydrostatic pressure (HP) on antidiuretic hormone (ADH) stimulated osmotic water flow (Jv) across the toad urinary bladder was evaluated. Jv for ADH-stimulated bladders was significantly reduced by an elevation of the serosal HP gradient to 1 cm H₂O. Subsequent elimination of the HP gradient resulted in a recovery of Jv. Serosal HP also caused a reversible increase in sucrose permeability (P sucrose). For ADH-treated bladders fixed with glutaraldehyde during serosal HP exposure, subsequent exposure to a mucosal or serosal HP gradient caused acceleration or inhibition of Jv, respectively. The reduction in ADH-associated Jv with serosal HP was apparently caused by a back-flux of water through a paracellular pathway. Jv and P sucrose were not affected by mucosal HP during ADH stimulation. The results suggest a specific sensitivity of a paracellular pathway to a small serosal HP gradient in bladders with ADH-stimulated water flow. The reversibility of this effect on P sucrose suggests that the elements comprising the apical junctions are dynamic structures capable of recovering at least some of their permeability properties.     

Coexistence of somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivity in some forebrain neurons

The indirect immunofluorescence technique was used to demonstrate the coexistence of somatostatin together with avian pancreatic polypeptide-like immunoreactivity within certain neurons of the rat forebrain. Numerous neurons containing these peptides were observed in the neocortex, hippocampus, olfactory tubercle, striatum, nucleus accumbens and lateral septum. In studies of serial sections stained alternately for these two peptides, and in restaining experiments, It could be determined that in many neurons in these areas these two peptides coexisted. In other brain areas such as the anterior periventricular hypothalamus, somatostatin cells were never found to contain avian pancreatic polypeptide-like immunoreactivity. Also, within the pancreas these two peptides were never found to coexist in the same cells. The findings represent a further example of the coexistence of more than one neuropeptide within a single neuron.     

Adhesion contact dynamics of HepG2 cells on galactose-immobilized substrates

The specific recognition between asialoglycoprotein receptor and galactose ligand at cell-substrate interfaces has been shown to mediate hepatocyte adhesion and maintain liver specific functions of hepatocytes. Conventionally, the success of hepatocyte attachment on engineered tissue scaffold is inferred from the degree of two-dimensional cell spreading that is measured by transmitted light microscopy. However, the actual contact mechanics and adhesion strength of hepatocytes during two-dimensional cell spreading has not been elucidated due to lack of biophysical probe. In this study, a novel biophysical technique known as confocal reflectance interference contrast microscopy (C-RICM) in conjunction with phase contrast microscopy is utilized to probe the adhesion dynamics, contact mechanics and two-dimensional spreading kinetics of HepG2 cells on galactose immobilized and collagen gel coated substrates. C-RICM demonstrates that HepG2 cells form strong adhesion contacts with both galactose-immobilized surfaces and collagen gel coated substrates. Moreover, HepG2 cells maintain their compact shapes in the presence of asialoglycoprotein receptor-mediated recognition while they become exceedingly spread under integrin-mediated adhesion on collagen gel coated substrate. The initial rate of adhesion contact formation and the steady-state adhesion energy of HepG2 cell population are highest on substrate conjugated with galactose ligand via a longer spacer. The adhesion dynamics and final adhesion energy of HepG2 cells depends both on the type of ligand-receptor interaction and the length of spacer between the ligand and substrate. Most importantly, new biophysical insights into the initial hepatocyte attachment that are critical for hepatocyte culture are provided through the decomposition of two-dimensional spreading and adhesion contact formation on bio-functional substrates.     

Assessment of the COBAS Amplicor HBV Monitor Test for quantitation of serum hepatitis B virus DNA levels

Treatment of patients with chronic hepatitis B virus (HBV) infections with potent antiviral therapy often results in dramatic reductions in the levels of viremia to very low levels. Monitoring of serum HBV DNA levels is a consistent method for the assessment of antiviral potency; however, widely used hybridization assays for the monitoring of HBV DNA levels have limited sensitivities and are not effective for the monitoring of patients whose serum HBV DNA levels have decreased to below approximately 700,000 HBV genomes/ml. The objective of the present study was to assess a PCR-based assay (the COBAS-AM assay) for quantitation of serum HBV DNA levels and to compare the results of the COBAS-AM assay with those of a solution hybridization assay with a radiolabeled probe. The precision and accuracy of the assay were determined with low-positive and high-positive controls consisting of a plasmid DNA molecule containing HBV-specific primer binding regions, and the sensitivity of the assay was determined by using serial dilutions of sera from subjects with chronic HBV infection. HBV DNA levels were quantitated in 1,695 serum samples from subjects with chronic HBV infection who were enrolled in clinical trials of lamivudine in North America or Asia. The COBAS-AM assay demonstrated high levels of inter- and intra-assay precision and accuracy, and the linear range of the COBAS-AM assay was greater than that of the solution hybridization assay. The assay is linear over a 3-log(10) range and is able to quantitate serum HBV DNA at levels 3 log(10) lower than those that can be detected by the solution hybridization assay. We found that the COBAS-AM assay is an accurate PCR-based assay for quantitation of serum HBV DNA levels in subjects with chronic HBV infection.     

Splice variants of the relaxin and INSL3 receptors reveal unanticipated molecular complexity

LGR7 and LGR8 are G protein-coupled receptors that belong to the leucine-rich repeat-containing G-protein coupled receptor (LGR) family, including the thyroid-stimulating hormone (TSH), LH and FSH receptors. LGR7 and LGR8 stimulate cAMP production upon binding of the cognate ligands, relaxin and insulin-like peptide 3 (INSL3), respectively. We cloned several novel splice variants of both LGR7 and LGR8 and analysed the function of four variants. LGR7.1 is a truncated receptor, including only the N-terminal region of the receptor and two leucine rich repeats. In contrast, LGR7.2, LGR7.10 and LGR 8.1 all contain an intact seven transmembrane domain and most of the extracellular region, lacking only one or two exons in the ectodomain. Our analysis demonstrates that although LGR7.10 and LGR8.1 are expressed at the cell surface, LGR7.2 is predominantly retained within cells and LGR7.1 is partially secreted. mRNA expression analysis revealed that several variants are co-expressed in various tissues. None of these variants were able to stimulate cAMP production following relaxin or INSL3 treatment. Unexpectedly, we did not detect any direct specific relaxin or INSL3 binding on any of the splice variants. The large number of receptor splice variants identified suggests an unforeseen complexity in the physiology of this novel hormone-receptor system.     

What Can Be Learned from a Lattice Analysis of a Laterality Questionnaire?

In order to develop a genetic study of human laterality, we conducted an exploratory study concerning one aspect of this phenotype: lattice analysis was used to determine whether the structure of manual preference was the same for right- and left-handers. The study highlights the links between two sets — participants and actions — describing binary data, by ordering them dually along a Galois lattice: participants were ordered according to subsets of actions for which they used only their writing hand, while actions were ordered according to sub-groups using their writing hand to perform them. The twelve item questionnaire of Annett was analysed in two samples of 94 adult right-hand and 31 left-hand writers. The items did not have the same categorical impact for the two groups of left- and right-hand writers. The behaviour of right-handers appeared globally more stereotyped. On the contrary, left-handed profiles were nearly all distinct. To explore these conclusions more thoroughly in the general population would certainly require greater samples. Nevertheless in both cases the observed structures were highly dimensional, a result that would grow stronger as the group sizes increase. Hence whereas some questionnaires purport to evaluate laterality along an unidimensional continuum, the present analysis questions such a strong assumption providing evidence to the contrary.     

Pre- and postnatal depression and coping: a comparative approach

BACKGROUND: The assessment of perinatal depressions and coping style. Methods: With depression scales (EPDS, GHQ.12) and Carver's BriefCope, the authors compared the prevalence rates of pre and postnatal depression in a cohort of 277 French women. RESULTS: Their work revealed very high levels of prenatal depression (almost 20%) and less important but nonetheless sizeable rates (11%) of postnatal depression, making such perinatal depressions a major public health concern. The coping styles proposed in Carver's public health BriefCope questionnaire make it possible to significantly differentiate during these two periods between depressive women and their non-depressed counterparts. CONCLUSIONS: This enables us to underline factors of risk and protection suggesting the importance of setting up compensatory and preventive systems and evaluating their pertinence in the framework of future research.     

Inactivation of the peroxisomal ABCD2 transporter in the mouse leads to late-onset ataxia involving mitochondria, Golgi and endoplasmic reticulum damage

ATP-binding cassette (ABC) transporters facilitate unidirectional translocation of chemically diverse substances, ranging from peptides to lipids, across cell or organelle membranes. In peroxisomes, a subfamily of four ABC transporters (ABCD1 to ABCD4) has been related to fatty acid transport, because patients with mutations in ABCD1 (ALD gene) suffer from X-linked adrenoleukodystrophy (X-ALD), a disease characterized by an accumulation of very-long-chain fatty acids (VLCFAs). Inactivation in the mouse of the abcd1 gene leads to a late-onset neurodegenerative condition, comparable to the late-onset form of X-ALD [Pujol, A., Hindelang, C., Callizot, N., Bartsch, U., Schachner, M. and Mandel, J.L. (2002) Late onset neurological phenotype of the X-ALD gene inactivation in mice: a mouse model for adrenomyeloneuropathy. Hum. Mol. Genet., 11, 499-505.]. In the present work, we have generated and characterized a mouse deficient for abcd2, the closest paralog to abcd1. The main pathological feature in abcd2-/- mice is a late-onset cerebellar and sensory ataxia, with loss of cerebellar Purkinje cells and dorsal root ganglia cell degeneration, correlating with accumulation of VLCFAs in the latter cellular population. Axonal degeneration was present in dorsal and ventral columns in spinal cord. We have identified mitochondrial, Golgi and endoplasmic reticulum damage as the underlying pathological mechanism, thus providing evidence of a disturbed organelle cross-talk, which may be at the origin of the pathological cascade.