Osteocyte hypoxia: a novel mechanotransduction pathway

Bone is a unique tissue in which to examine mechanotransductiondue to its essential role in weight bearing. Within bone, the osteocyteis an ideal cellular mechanotransducer candidate. Because osteocytesreside distant from the blood supply, their metabolic needs are met bya combination of passive diffusion and enhanced diffusion, arising whenthe tissue is loaded during functional activity. Therefore, wehypothesized that depriving a bone of mechanical loading (and thuseliminating diffusion enhanced by loading) would rapidly induceosteocyte hypoxia. Using the avian ulna model of disuse osteopenia, wefound that 24 h of unloading results in significant osteocyte hypoxia(8.4 ± 1.8%) compared with control levels (1.1 ± 0.5%;P = 0.03). Additionally, we present preliminary data suggesting that a brief loading regimen is sufficient to rescue osteocytes from this fate. The rapid onset of the observed osteocyte hypoxia, the inhibition of hypoxia by brief loading, and thecellular consequences of oxygen deprivation are suggestive of a novelmechanotransduction pathway with implications across organ systems.

     

Heritable variation in locomotion,reward sensitivity and impulsive behaviors in a genetically diverse inbred mouse panel

Drugs of abuse, including alcohol and stimulants like cocaine, produce effects that are subject to individual variability, and genetic variation accounts for at least a portion of those differences. Notably, research in both animal models and human subjects point toward reward sensitivity and impulsivity as being trait characteristics that predict relatively greater positive subjective responses to stimulant drugs. Here we describe use of the eight collaborative cross (CC) founder strains and 38 (reversal learning) or 10 (all other tests) CC strains to examine the heritability of reward sensitivity and impulsivity traits, as well as genetic correlations between these measures and existing addiction-related phenotypes. Strains were all tested for activity in an open field and reward sensitivity (intake of chocolate BOOST®). Mice were then divided into two counterbalanced groups and underwent reversal learning (impulsive action and waiting impulsivity) or delay discounting (impulsive choice). CC and founder mice show significant heritability for impulsive action, impulsive choice, waiting impulsivity, locomotor activity, and reward sensitivity, with each impulsive phenotype determined to be non-correlating, independent traits. This research was conducted within the broader, inter-laboratory effort of the Center for Systems Neurogenetics of Addiction (CSNA) to characterize CC and DO mice for multiple, cocaine abuse related traits. These data will facilitate the discovery of genetic correlations between predictive traits, which will then guide discovery of genes and genetic variants that contribute to addictive behaviors.     

What tissue bankers should know about the use of allograft blood vessels

Vascular allografts have been used by surgeons with varying levels of enthusiasm over the last 100 years, to treat a wide variety of vascular conditions. This article reviews the history of vascular allografts, the current indications for use, and the background to current retrieval, processing and cryopreservation techniques.     

The effects of a collagenous extracellular matrix on fibroblast membrane organization : An ESR spin label study

Human skin fibroblasts, both in suspension and cultured within a three-dimensional collagen matrix have been examined by electron spin resonance ESR using the probe 5-doxyl stearic acid. The order of the plasma membrane was found to be strongly influenced by the collagen matrix, being greater for cells within the collagen gel than in suspension. The collagen cultures used in this study were either left attached to the walls of the plastic culture dish (‘attached’ gels) or dislodged and allowed to float freely in the culture medium (‘floating’ gels). Membrane order increased with time in attached gels, reaching a steady value after 2–3 h. A further increase in order was observed when floating gels were prepared 24 h later. Cell morphology within the collagen gel culture was observed to vary considerably, with time and mode of culture. Increased order, over that observed in suspension, was also found for cells attached to other substrata. The data indicate that the increase in membrane order observed in cells embedded within a three-dimensional collagen gel matrix compared with cells in suspension does not correlate with a particular cell morphology in the gel, but rather appears to result from the establishment of adhesive interactions with the surrounding collagen fibres.     

Analysis of alloantisera against bovine lymphocytes. Joint report of the 1st International Bovine Lymphocyte Antigen (BoLA) Workshop

The results and agreements of the 1st international BoLA workshop, held in Edinburgh, Scotland in August 1978, are reported. Most of these concern the results from a comparison test of 249 alloantisera to bovine lymphocytes, the antisera being contributed by 9 laboratories. These sera were compared directly in Edinburgh on a panel of lymphocytes from 130 cattle of 21 breeds. In the micro-lymphocytotoxicity test used 75% of the sera reacted. Sixty eight of these sera were grouped into clusters according to their reaction patterns against the lymphocyte panel. Eleven of these clusters were clearly defined and were given workshop BoLA designations. In addition 22 sera were assigned to subgroups of the agreed clusters. There was no evidence that the method of production of the sera had any effect on their specificity.
Although genetic data was not available, the phenotypes of the test panel of lymphocytes are consistent with the clusters detecting antigens controlled by multiple alleles at a single autosomal locus. It was agreed to name the genetic region where this putative locus is located BoLA (bovine lymphocyte antigen).     

Reconstructing disease outbreaks from genetic data: a graph approach

Epidemiology and public health planning will increasingly rely on the analysis of genetic sequence data. In particular, genetic data coupled with dates and locations of sampled isolates can be used to reconstruct the spatiotemporal dynamics of pathogens during outbreaks. Thus far, phylogenetic methods have been used to tackle this issue. Although these approaches have proved useful for informing on the spread of pathogens, they do not aim at directly reconstructing the underlying transmission tree. Instead, phylogenetic models infer most recent common ancestors between pairs of isolates, which can be inadequate for densely sampled recent outbreaks, where the sample includes ancestral and descendent isolates. In this paper, we introduce a novel method based on a graph approach to reconstruct transmission trees directly from genetic data. Using simulated data, we show that our approach can efficiently reconstruct genealogies of isolates in situations where classical phylogenetic approaches fail to do so. We then illustrate our method by analyzing data from the early stages of the swine-origin A/H1N1 influenza pandemic. Using 433 isolates sequenced at both the hemagglutinin and neuraminidase genes, we reconstruct the likely history of the worldwide spread of this new influenza strain. The presented methodology opens new perspectives for the analysis of genetic data in the context of disease outbreaks.     

The collagenous matrix of bovine predentine.

Predentine obtained from bovine teeth by microdissection was solubilized by cyanogen bromide cleavage. The electrophoretic mobility of the resultant peptides was established on polyacrylamide gel and the amino acid composition of several peptides was determined. The data clearly indicated that this collagen is entirely of the Type I genetic species. No differences were detected between the predentine and dentine collagens except that the mature tissue was more highly crosslinked. Nevertheless the amount of stable cross-link formed in the predentine was higher than expected for an immature tissue.