Therapeutic Approaches to ModulatingGlutathione Levels as a Pharmacological strategy in Alzheimer's Disease.

Accumulating evidence has suggested the involvement of oxidative stress in the pathogenesis of Alzheimer's disease (AD).The main endogenousantioxidant,glutathione (GSH),has been shown to decline with ageing and in several age-related degenerative diseases, including AD. Potential options for replenishing GSH levels as a therapeutic target to treat these conditions include the administration of GSH itself, and low toxicity forms of the limiting amino acid for GSH synthesis; cysteineHowever, passive GSH uptake is limited due to an unfavourable concentration gradient between the plasma and cytosol. Similarly, cysteine prodrugs have demonstrated limited efficacyto elevatedepleted GSH levels in several in vivo and in vitro models of disease.It has beensuggestedthat the decline in GSH levels in AD, may be associated with down regulation ofGSH homeostasis rather than substrate limitation. Cellular GSH homeostasis is regulatedby non-allosteric feedback inhibition exerted by GSH on glutamate cysteine ligase (GCL), which is responsible for the synthesis of the GSH precursor γ-glutamylcysteine (GGC). In conditions involving down regulated GSH homeostasis, GGC serves asa crucialrate-limiting substrate for GSH synthetase, the main enzyme responsible for condensing glycine with GGC to form the final thiol tripeptide, GSH. In this review, we focus on the therapeutic potential of GGC to elevate cellular GSH levels. We also discuss the efficacy of GGC prodrugs which would be taken up and converted by the unregulated GS to GSH,andthe administration of modified GSH compounds, such as GSH esters that could potentially overcome the concentration gradient that prohibits passive GSH uptake, in AD.

Safety assessment of gamma-glutamylcysteine sodium salt.

γ-Glutamylcysteine (GGC) is a relatively unexplored option for the treatment of chronic glutathione depletion related disorders that involve down regulation of GGC synthetase. High purity GGC (sodium salt) has only recently become available and, given its reactive capacity, required an investigation of its safety profile. In this report, GGC sodium salt was demonstrated to be safe according to Organisation for Economic Cooperation and Development (OECD) toxicology protocols for acute and repeated doses. No mortalities or adverse effects were observed in Wistar rats following the acute oral (gavage) administration of 2000mg sodium GGC /kg body weight. No animal deaths occurred with daily administration (1000mg/kg sodium GGC) over 90days, with a post trial 28day observation period. GGC had no significant effect on feed consumption, body weights, physical appearance, neurological behaviour and urine chemistry. No consistent significant differences between treatment groups were observed in haematological and clinical chemistry parameters. Similarly, no post-mortem necroscopically identified abnormalities could be attributed to GGC. Based on these observations, sodium GGC can be classed as not acutely toxic at 2000mg/kg, with a no-observed-adverse-effect level (NOAEL) of at least 1000mg/kg/day for systemic toxicology from repeated dose oral gavage administration.

Isolation and chromosomal assignment of canine genomic BAC clones representing 25 cancer-related genes.

An extensive number of genes have been implicated in the initiation and progression of human cancers, aiding our understanding of the genetic aetiology of this highly heterogeneous disease. In order to facilitate extrapolation of such information between species, we have isolated and physically mapped the canine orthologues of 25 well-characterised human cancer-related genes. The identity of PCR products representing each canine gene marker was first confirmed by DNA sequencing analysis. Each product was then radiolabelled and used to screen a genomic BAC library for the domestic dog. The chromosomal location of each positive clone in the canine karyotype was determined by fluorescence in situ hybridisation (FISH) onto canine metaphase preparations. Of the 25 genes, the FISH localisation of 21 correlated fully with that expected on the basis of known regions of conserved synteny between the human and canine genomes. Three correlated less closely, and the chromosomal location of the remaining marker showed no apparent correlation with current comparative mapping data. In addition to generating useful comparative mapping information, this panel of markers will act as a valuable resource for detailed study of candidate genes likely to be involved in tumourigenesis, and also forms the basis of a canine cancer-gene genomic microarray currently being developed for the study of unbalanced genomic aberrations in canine tumours.

Chromosome-specific single-locus FISH probes allow anchorage of an 1800-marker integrated radiation-hybrid/linkage map of the domestic dog genome to all chromosomes.

We present here the first fully integrated, comprehensive map of the canine genome, incorporating detailed cytogenetic, radiation hybrid (RH), and meiotic information. We have mapped a collection of 266 chromosome-specific cosmid clones, each containing a microsatellite marker, to all 38 canine autosomes by fluorescence in situ hybridization (FISH). A 1500-marker RH map, comprising 1078 microsatellites, 320 dog gene markers, and 102 chromosome-specific markers, has been constructed using the RHDF5000-2 whole-genome radiation hybrid panel. Meiotic linkage analysis was performed, with at least one microsatellite marker from each dog autosome on a panel of reference families, allowing one meiotic linkage group to be anchored to all 38 dog autosomes. We present a karyotype in which each chromosome is identified by one meiotic linkage group and one or more RH groups. This updated integrated map, containing a total of 1800 markers, covers >90% of the dog genome. Positional selection of anchor clones enabled us, for the first time, to orientate nearly all of the integrated groups on each chromosome and to evaluate the extent of individual chromosome coverage in the integrated genome map. Finally, the inclusion of 320 dog genes into this integrated map enhances existing comparative mapping data between human and dog, and the 1000 mapped microsatellite markers constitute an invaluable tool with which to perform genome scanning studies on pedigrees of interest.

Acoustooptic analysis of high frequency wideband sound field schlieren imaging.

Schlieren imaging of acoustic waves has been used routinely for at least half a century. The nature of the image has conventionally been analyzed by various ray tracing techniques or wavefront corrugation calculations. These are restricted to low sound frequencies or thin sound fields. We present a novel method, based on acoustooptic plane wave interaction theory, that not only is applicable to high frequencies but reveals some unexpected features of schlieren imaging.

Course evaluation in post-basic education.

Course evaluation is defined 'as the collection and use of information in order to make decisions about an educational programme' (Cronbach 1963). The study described in this paper was undertaken by members of the professional and research staff of the Joint Board of Clinical Nursing Studies, London. The paper describes how the need for work on course evaluation arose and how a package was developed and piloted in 15 course centres with a total of 205 students. The ways in which the package is being used by schools of nursing and colleges of higher and further education is also described. The philosophy that evaluation has an important part to play in developing dynamic and sound educational systems is emphasized. Evaluation should be an integral part of every course and planned at the outset with other parts of the detailed course programme, involving both students and teachers in measuring the effectiveness of the course.