Biomedical subjects
Publications and source records attributed to P A Johnston.
This article reports on the coordination of communications skills training in veterinary schools in the United Kingdom and Ireland and describes the progress and status of training that is occurring in six of these schools.
In this review we describe recent progress in barley (Hordeum vulgare) improvement through hybridisation with its wild relatives. We have focused on one species in the secondary genepool of cultivated barley, namely H. bulbosum. This wild species has desirable traits, such as disease resistance, that are worthwhile transferring to its cultivated relative. Progress has been achieved through developing partially fertile interspecific hybrids that have been selfed or backcrossed to barley. We present the results of cytogenetic and molecular analyses that have enabled us to characterise and produce agronomically useful recombinant lines obtained from the hybrids.
Hordeum vulgare (cultivated barley) x H. bulbosum (bulbous barley grass) hybrids have been used to obtain disease-resistant recombinant lines (RLs). The RLs contain chromatin transferred from the wild species mostly onto the long arms of recipient barley chromosomes. To determine whether differences in meiotic metaphase I (MI) associations between the long and short arms of homologous chromosomes can account for the preponderance of introgressions on the long arms, we carried out fluorescent in situ hybridisation on MI chromosome preparations obtained from pollen mother cells of a diploid interspecific hybrid. By using various probes, we established that MI associations between the long arms occurred more frequently than between the short arms for the five chromosomes tested.
In this study we explored the use of butter as a sampling matrix to reflect the regional and global scale distribution of PCBs and selected organochlorine pesticides/metabolites in air. This was because persistent organic pollutants (POPs) concentrate in dairy fats, where concentrations are controlled by feed intake (primarily from pasture/silage), which is in turn primarily controlled by atmospheric deposition. Butter sigmaPCB concentrations varied by a factor of approximately 60 in 63 samples from 23 countries. They were highest in European and North American butter and lowest in southern hemisphere (Australian, New Zealand) samples, consistent with known patterns of historical global usage and estimated emissions. Concentrations in butter reflected differences in the propensity of PCB congeners to undergo long range atmospheric transport from global source regions to remote areas and the relatively even distribution of HCB in the global atmosphere. Concentrations of p,p'-DDT, p,p'-DDE, and HCH isomers all varied over many orders of magnitude in the butter samples, with highest levels in areas of current use (e.g. India and south/central America for DDT; India, China, and Spain for HCH). We conclude that butter is sensitive to local, regional, and global scale spatial and temporal atmospheric trends of many POPs and may therefore provide a useful sampling medium for monitoring purposes. However, to improve the quantitative information derived on air concentrations requires an awareness of climatic and livestock management factors which influence air-milk fat transfer processes.
Absolute pitch (AP) is the ability to recognize a pitch, without an external reference. By surveying more than 600 musicians in music conservatories, training programs, and orchestras, we have attempted to dissect the influences of early musical training and genetics on the development of this ability. Early musical training appears to be necessary but not sufficient for the development of AP. Forty percent of musicians who had begun training at <=4 years of age reported AP, whereas only 3% of those who had initiated training at >=9 years of age did so. Self-reported AP possessors were four times more likely to report another AP possessor in their families than were non-AP possessors. These data suggest that both early musical training and genetic predisposition are needed for the development of AP. We developed a simple computer-based acoustical test that has allowed us to subdivide AP possessors into distinct groups, on the basis of their performance. Investigation of individuals who performed extremely well on this test has already led us to identify several families that will be suitable for studies of the genetic basis of AP.
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By mid-August 1995, 55% of broiler embryos in North America were vaccinated for Marek's disease using the INOVOJECT system, with 201 INOVOJECT machines placed with 16 of the top 25 poultry producers, providing the industry with the capacity to inject in excess of 400 million eggs per month or about 5 billion eggs per annum. In ovo administration of a bursal disease antibody-infectious bursal disease virus (BDA-IBDV) complexed vaccine to specific-pathogen-free (SPF) embryos was safer and more potent than conventional IBDV vaccine alone because it delayed the appearance of bursal lesions, produced no early mortality, produced higher geometric mean antibody titers against IBDV, and generated protective immunity against challenge. In ovo administration of a BDA-IBDV complexed vaccine to broiler embryos generated antibody titers against IBDV sooner than conventional virus vaccinates, and generated protective immunity against challenge Direct DNA injection of plasmid DNA encoding beta-galactosidase into breast muscle in ovo and posthatch was an effective means to achieve both gene transfer and expression, with potential for the development of gene vaccines using plasmids encoding protective antigens from poultry pathogens. In ovo administration of 800 U chicken myelomonocytic growth factor (cMGF), a chicken hematopoietic cytokine for cells of the monocytic-granulocytic lineages, significantly reduced mortality associated with Escherichia coli exposure within the hatcher when compared to PBS controls (6.1 vs 12.4, P < or = 0.05), but not when compared to a yeast expression control. A procedure was developed enabling injection prior to the onset of incubation without compromising embryo viability. This in ovo injection process has opened up the window of embryo development during incubation for intervention, as illustrated by the 100% male phenotype produced in chicks hatching from eggs injected with aromatase inhibitor prior to incubation. These data illustrate some of the in ovo applications presently in use by the poultry industry, and under development or in research at EMBREX.
We have developed a high throughput screen to identify inhibitors of endothelial cell activation using E-selection cell-surface expression as a marker. Endothelial cell activation is an important component of both acute and chronic inflammatory disease. Inhibitors of this process represent potential therapeutic agents. A cell culture system for primary human umbilical vein endothelial cells was generated, including an analysis of donor variability, passage number, seeding density, and cost. The effects of IL-1 beta, TNF alpha, LPS, and an LPS-conditioned plasma product on E-selectin expression were characterized. E-selectin expression on the surface of IL-1-stimulated endothelial cells was quantified with a direct ELISA on fixed cell monolayers. Automation of the ELISA necessitated identification of methods for cell fixation, liquid handling, and compound addition which would maintain the integrity of the cell monolayer. The ELISA is inexpensive, reproducible, and suitable for high throughput primary cell assays, supporting a screening rate of 10,000 compounds/ week. The method is compatible with a broad chemical diversity, and the cellular format provides early information on the cellular uptake and cytotoxicity of compounds. We describe a screening paradigm which allowed us to identify inhibitors of endothelial cell activation and simultaneously discriminate their activity from their cytotoxic effects.
Synaptotagmin I is localized to synaptic vesicles where it functions in the calcium-triggered release of neurotransmitters. Here we demonstrate that synaptotagmin I covalently incorporated [3H]palmitate after metabolic labelling of PC-12 cells and rat brain synaptosomes. Labeling was localized to a tryptic fragment that contains a cluster of cysteine residues adjacent to the molecule's single transmembrane anchor. Neutral hydroxylamine released the [3H]palmitate from this fragment and increased its electrophoretic mobility, demonstrating that acylation occurs at the membrane-proximal cysteine cluster. In addition, hydroxylamine-induced mobility shifts were also apparent for synaptotagmins II and III, suggesting that posttranslational palmitoylation via thioester bonds may be a general modification of all synaptotagmins.
The records of 7086 patients reported to the MRC Glomerulonephritis Registry between 1978 and 1990 were examined; 1368 patients were aged > 60 years at the time of biopsy. In 1978 12% of patients aged > 60 years underwent biopsy, whereas in 1990 30% of patients were aged > 60 years. The most common reasons for biopsy were nephrotic syndrome (31%), acute renal failure (26%) and chronic renal failure (25%). In patients presenting with nephrotic syndrome, the most common histological appearance was membranous nephropathy (36.6%), minimal changes (11%) and amyloidosis (10.7%). Secondary nephrotic syndrome was associated with amyloidosis (32 patients), diabetes mellitus (11 patients) and carcinoma (10 patients). Glomerulonephritis in the elderly is not uncommon and the apparent increasing incidence is most likely due to an increased referral of patients for investigation rather than a true increase in the incidence of this condition.
Cholesteryl ester transfer protein (CETP) mediates the exchange of phospholipids and neutral lipids between the plasma lipoproteins, and plays an important role in high density lipoprotein (HDL) metabolism. While there are reports of low-level CETP secretion from cultured cells, the lack of a good model cell line has hampered the detailed study of CETP regulation and secretion. In this study, we have found that the human liposarcoma cell line, SW872, secretes cholesteryl ester transfer protein at levels substantially higher than observed from other cell lines. The secretion of CETP from this adipose-derived cell was up-regulated by 25-OH cholesterol and by low density lipoprotein (LDL) cholesterol in a concentration-dependent manner. Analysis of both full length and exon 9-deleted CETP mRNA demonstrated increases in response to LDL and 25-OH cholesterol, providing evidence for regulation at the message level. Our results suggest that the CETP-producing SW872 cell line may provide a model in which to study the regulation of this important modulator of lipoprotein metabolism.
During embryonic development, the components of the avian immune system undergo ontogeny in several distinct organs, including the bone marrow, spleen, thymus, and bursa of Fabricius. This process is regulated and controlled by the complex interactions of various cytokines and colony-stimulating factors (CSF). The objective was to examine the action of two different sources of hematopoietic growth factors, spleen-conditioned media (SCM) and chick embryo extract (CEE), on the proliferation of hematopoietic cells from various organs and on the differentiation of progenitor cells in semi-solid culture. Spleen and bone marrow cells obtained at Day 16 of incubation responded in a dose-dependent manner to the addition of SCM and CEE alone or in combination. No proliferative effect of SCM was observed on cells obtained from embryonic thymus or bursa. Clonal analysis of bone marrow and spleen cells suggested that CEE may contain the avian equivalents of stem cell factor, interleukin-3, granulocyte-macrophage CSF, granulocyte-CSF, and macrophage-CSF. Clonal analysis of SCM cultures suggested that in addition to myelomonocytic growth factor, which affects primarily macrophage-granulocyte lineages, a thrombocyte-CSF-like activity was also apparent. The SCM alone tended to act upon committed late progenitors. The combination of CEE and SCM amplified the size and the total number of colonies obtained and appeared to act synergistically upon progenitors with a high level of proliferative potential. This response on young progenitors was confirmed when cells were cultured in CEE and SCM prior to clonal analysis. These results document the presence of thrombocyte CSF in SCM and the effect of both CEE and SCM on the proliferative differentiation of avian embryonic hematopoietic progenitors.
Some 22,000 pilot whales (Globicephala melaena) were taken in the Faroe Islands between 1970 and 1992. It is known that tissues from these animals are widely consumed by the islanders. The position of these animals at the apex of a direct marine food chain renders them liable to accumulate toxic chemicals, such as metals and organochlorines. Although the consumption of contaminating metals in pilot whale tissues has been studied, the significance of blubber as a dietary source of organochlorine compounds has not been fully considered. This study reports levels of organochlorine and mercury contamination in the blubber of pilot whales taken in two Faroese kills. Published estimates of pilot whale tissue consumption are used to evaluate dietary organochlorine intake in relation to established national and international guidelines and clinical studies conducted in the North American Great Lakes.
We have reported that MG160, an intrinsic membrane sialoglycoprotein of the Golgi apparatus (GA), resides in the medial cisternae of the organelle (Gonatas et al. (1989) J. Biol. Chem. 264, 646-653). In order to resolve the question whether MG160 acquires sialic acid residues in the trans cisternae or trans-Golgi network (TGN) prior to its retrograde transport, we have examined the effects of brefeldin A (BFA) on the post-translational processing of MG160, and the distribution of internalized wheat germ agglutinin covalently linked with HRP (WGA-HRP), which labels the TGN (Gonatas et al. (1977) J. Cell Biol. 73, 1-13). In BFA-treated PC12 cells, MG160 acquires resistance to endo H, but fails to be sialylated. This effect occurs in parallel with the redistribution of MG160 into an ER compartment dispersed throughout the cytoplasm including the nuclear envelope, and the collapse of the WGA-HRP-labelled TGN into vesicles and tubules surrounding the centriole. These results suggest that MG160 is not sialylated in BFA-treated cells because it is sequestered from the sialyltransferase enzyme(s), presumably located in the TGN, and provide evidence supporting the hypothesis for a retrograde transport pathway that recycles resident GA proteins, including MG160, between the Golgi cisternae and the TGN. To examine further the above hypothesis we studied cells treated with BFA and then allowed to recover from the effect of the drug for various lengths of time. After 15 minutes of recovery, cisternae of the Golgi apparatus, typically found in the pericentriolar region, are labeled by both MG160 and WGA-HRP.(ABSTRACT TRUNCATED AT 250 WORDS)
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In 1988 and 1989 tissue samples were obtained from the grey seal (Halichoerus grypus) population found in the Dee estuary in the north west of England and from harbour seals (Phoca vitulina) from the populations in the Wash and north east Scotland and analysed for mercury and organochlorine compounds. Adult seals from the Dee estuary were highly contaminated with mercury and polychlorinated biphenyls (PCBs), and one animal from the Dee contained traces of dichlorodiphenyltrichloroethane (DDT), suggesting the recent use of this banned pesticide. The levels of hexachlorobenzene in the livers of two Dee seals exceeded those in the blubber, possibly indicating liver malfunction or recent exposure. The same relationship was found for hexachlorobenzene in three specimens from the Wash and, in one of these animals, the liver was also more highly contaminated than the blubber with dieldrin and PCBs. Levels of contamination were lower in seals from the Wash and even lower in animals sampled in Scotland, where only dichlorophenyldichloroethylene, the metabolite of DDT, was routinely detected. The toxicological significance of the results is discussed, particularly in relation to the mortality observed in the seal epizootic of 1988.