Lung disease in mice with cystic fibrosis

The leading cause of mortality and morbidity in humans with cystic fibrosis is lung disease. Advances in our understanding of the pathogenesis of the lung disease of cystic fibrosis, as well as development of innovative therapeutic interventions, have been compromised by the lack of a natural animal model. The utility of the CFTR-knockout mouse in studying the pathogenesis of cystic fibrosis has been limited because of their failure, despite the presence of severe intestinal disease, to develop lung disease. Herein, we describe the phenotype of an inbred congenic strain of CFTR-knockout mouse that develops spontaneous and progressive lung disease of early onset. The major features of the lung disease include failure of effective mucociliary transport, postbronchiolar over inflation of alveoli and parenchymal interstitial thickening, with evidence of fibrosis and inflammatory cell recruitment. We speculate that the basis for development of lung disease in the congenic CFTR-knockout mice is their observed lack of a non-CFTR chloride channel normally found in CFTR-knockout mice of mixed genetic background.     

Epstein-Barr virus infects and induces apoptosis in human neutrophils

Tibialis anterior and extensor digitorum longus muscles were partially denervated by cutting the L4 spinal nerve in three-day-old rats. The ultrastructure of the intact axons to these muscles in the L5 spinal nerve was examined in nine-day-old rats. In the control L5 spinal nerve, myelinated and unmyelinated axons were intermingled throughout the cross-section of the nerve, while on the operated side the nerve contained areas with predominantly small unmyelinated immature axons. The number of motoneurons innervating the partially denervated muscles was established by retrograde labelling with Diamidino Yellow. In nine- and 21-day-old rats, the number of labelled motoneurons on the partially denervated side, expressed as a percentage of the control side, was 26.1 +/- 5.5% and 20.7 +/- 3.0%, respectively. The response of these uninjured motoneurons to axotomy was tested. The axons of the motoneurons to the partially denervated muscles were crushed at nine days and the numbers of labelled motoneurons in the spinal cord of these rats counted at 21 days of age. Only 4.9 +/- 2.0% labelled motoneurons were seen on the operated side, as opposed to 20.7 +/- 3.0% present in animals without sciatic nerve injury. In normal animals, nerve injury at nine days does not cause motoneuron death. Thus, motoneurons to partially denervated muscles (i) have axons with several immature features and (ii) remain susceptible to axotomy-induced death for much longer than normal.     

Developmental and tissue-specific expression of human CD4 in transgenic rabbits

A major obstacle to understanding AIDS is the lack of a suitable small animal model for studying HIV-1 infection and the subsequent development of AIDS, and for testing diagnostic, therapeutic, and preventive modalities. Our goal is to produce a rabbit model for the study of AIDS. Here we report on the generation of transgenic rabbits that express the human CD4 (hCD4) gene. The transgene, which contains the coding region for hCD4 and approximately 23 kb of sequence upstream of the translation start site, was used previously to direct hcD4 expression on the surface of CD4+ T cells of transgenic mice (Gillespie et al., 1993: Mol Cell Biol 13:2952-2958). The hCD4 transgene was detected in five males and two females derived from the microinjection in five males and two females derived from the microinjection of 271 rabbit embryos. Both hCD4 RNA and protein were expressed in peripheral blood lymphocytes (PBLs) from all five males but neither of the females. Human CD4 was expressed on PBLs from F1 offspring of all founder males. T-cell subset analysis revealed that hCD4 expression was restricted to rabbit CD4 (rCD4) expressing lymphocytes; mature rCD4- rCD8+ lymphocytes did not express hCD4. In preliminary studies, PBLs from hCD4 transgenic rabbits produced greater amounts of HIV-1 p24 core protein following HIV-1 infection in vitro than HIV-1 p24 antigen in nontransgenic rabbit infected cultures. These results extend to rabbits our previous observation that this transgene contains the sequence elements required for high-level expression in the appropriate cells of transgenic mice. Furthermore, these and previous studies demonstrating that expression of hCD4 protein enhances HIV-1 infection of rabbit T cells in vitro, coupled with reports that normal, nontransgenic rabbits are susceptible to HIV-1 infection, suggests that the hCD4 transgenic rabbits described herein will have an increased susceptibility to HIV-1 infection. In vivo HIV-1 infection studies with these rabbits are under way.     

Optimal approach for upstream fish passage design: One-size-fits-all or made-to-order?

Nearly 60,000 large dams (higher than 15 m) occur worldwide in addition to an estimated 16 million smaller impoundments with individual surface areas larger than 100 m². The resulting habitat fragmentation threatens global riverine biodiversity and sustainable fish populations. Two opposing approaches for selecting fish passage designs to mitigate river fragmentation are possible: develop a limited number of standardized (reference) designs from which a design for a candidate dam is selected (one-size-fits-all approach) versus conduct scientific fish passage studies specific to each dam and targeted fish species (made-to-order approach). The two approaches vary in probability of effectiveness, cost of supporting biological studies, and overall project cost and schedule impact. To address this conundrum, we analyzed 73 USA dams to identify two groups that differed markedly in fish passage planning approaches. Snake River dams are similar in design, flow, geological setting, and target fish species. By contrast, Mississippi River dams are relatively dissimilar in design, flow, and geological setting but generally similar in target fish species. We conclude that the more similar a candidate dam for fish passage is to a reference set of similar dams (i.e., the Snake River dams), then the more likely fish passage technology can be successfully extrapolated to a proposed dam in the same or a nearby watershed. As a general strategy, we recommend that dams in a region be clustered using key hydrologic, structural, operational, and biological variables. These variables can be used to assign a new dam or retrofit an existing dam to a cluster to which they are most similar, thereby optimally extending existing knowledge to new applications. In the process, reliance on the less efficient and more expensive made-to-order approach can be reduced.     

Selective hydrogen absorption from gaseous mixtures by BCC Ti-V alloys

Hydrogen absorption behaviour of the BCC Ti-V alloys has been studied as related to their potential application for the selective hydrogen absorption from mixtures with active gases containing CO and steam at high temperatures. Alloys and their hydrides were characterised using Scanning Electron Microscopy (SEM), Thermal Desorption Spectroscopy (TDS), Temperature Programmed Reaction (TPR) and in situ synchrotron X-ray powder diffraction (SR-XRD). BCC Ti_0.8V_0.2 and Ti_0.9V_0.1 were able to absorb 3.95 wt.% H by forming a FCC type hydride γ−(Ti,V)H₂. Nanoparticles of Pd and Pd/Pt were electroless deposited on the surface of the hydrides to catalyse hydrogen absorption. TPR tests showed that such alloys were capable of absorbing hydrogen even when substantial amounts of CO and H₂O were present in the gas stream. Nanoparticles of Pd/Pt provide a better performance as compared to Pd alone. In situ SR-XRD has been used to probe the mechanisms of hydrogenation and dehydrogenation.     

Spinal Cord T-Cell Infiltration in the Rat Spared Nerve Injury Model: A Time Course Study

The immune system is involved in the development of neuropathic pain. In particular, the infiltration of T-lymphocytes into the spinal cord following peripheral nerve injury has been described as a contributor to sensory hypersensitivity. We used the spared nerve injury (SNI) model of neuropathic pain in Sprague Dawley adult male rats to assess proliferation, and/or protein/gene expression levels for microglia (Iba1), T-lymphocytes (CD2) and cytotoxic T-lymphocytes (CD8). In the dorsal horn ipsilateral to SNI, Iba1 and BrdU stainings revealed microglial reactivity and proliferation, respectively, with different durations. Iba1 expression peaked at D4 and D7 at the mRNA and protein level, respectively, and was long-lasting. Proliferation occurred almost exclusively in Iba1 positive cells and peaked at D2. Gene expression observation by RT-qPCR array suggested that T-lymphocytes attracting chemokines were upregulated after SNI in rat spinal cord but only a few CD2/CD8 positive cells were found. A pronounced infiltration of CD2/CD8 positive T-cells was seen in the spinal cord injury (SCI) model used as a positive control for lymphocyte infiltration. Under these experimental conditions, we show early and long-lasting microglia reactivity in the spinal cord after SNI, but no lymphocyte infiltration was found.