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Biomedical subjects

T Lavery

Publications and source records attributed to T Lavery.

9 recordsLinked to original sources
PubMed2001

Linkage disequilibrium in the human genome.

With the availability of a dense genome-wide map of single nucleotide polymorphisms (SNPs), a central issue in human genetics is whether it is now possible to use linkage disequilibrium (LD) to map genes that cause disease. LD refers to correlations among neighbouring alleles, reflecting 'haplotypes' descended from single, ancestral chromosomes. The size of LD blocks has been the subject of considerable debate. Computer simulations and empirical data have suggested that LD extends only a few kilobases (kb) around common SNPs, whereas other data have suggested that it can extend much further, in some cases greater than 100 kb. It has been difficult to obtain a systematic picture of LD because past studies have been based on only a few (1-3) loci and different populations. Here, we report a large-scale experiment using a uniform protocol to examine 19 randomly selected genomic regions. LD in a United States population of north-European descent typically extends 60 kb from common alleles, implying that LD mapping is likely to be practical in this population. By contrast, LD in a Nigerian population extends markedly less far. The results illuminate human history, suggesting that LD in northern Europeans is shaped by a marked demographic event about 27,000-53,000 years ago.

Alleles↗
PubMed2000

Immune recognition of swine vesicular disease virus structural proteins: novel antigenic regions that are not exposed in the capsid.

Swine vesicular disease virus (SVDV) is an enterovirus of the Picornaviridae family that belongs to the coxsackievirus B group. A number of antigenic sites have been identified in SVDV by analysis of neutralizing monoclonal antibody-resistant mutants and shown to be exposed on the surface of the capsid. In this paper we have identified seven new immunodominant antigenic regions in SVDV capsid proteins by a peptide scanning method, using a panel of sera from infected pigs. When these antigenic regions were located in the capsid by using a computer-generated three-dimensional model of the virion, one was readily exposed on the surface of the virus and the remaining sites were located facing the inner side of the capsid shell, at subunit contacts, or in the interior of the subunit structure.

Animals↗
PubMed2000

Toward a more accurate quantitation of the activity of recombinant retroviruses: alternatives to titer and multiplicity of infection.

In this paper, we present a mathematical model with experimental support of how several key parameters govern the adsorption of active retrovirus particles onto the surface of adherent cells. These parameters, including time of adsorption, volume of virus, and the number, size, and type of target cells, as well as the intrinsic properties of the virus, diffusion coefficient, and half-life (t(1/2)), have been incorporated into a mathematical expression that describes the rate at which active virus particles adsorb to the cell surface. From this expression, we have obtained estimates of C(vo), the starting concentration of active retrovirus particles. In contrast to titer, C(vo) is independent of the specific conditions of the assay. The relatively slow diffusion (D = 2 x 10(-8) cm(2)/s) and rapid decay (t(1/2) = 6 to 7 h) of retrovirus particles explain why C(vo) values are significantly higher than titer values. Values of C(vo) also indicate that the number of defective particles in a retrovirus stock is much lower than previously thought, which has implications especially for the use of retroviruses for in vivo gene therapy. With this expression, we have also computed AVC (active viruses/cell), the number of active retrovirus particles that would adsorb per cell during a given adsorption time. In contrast to multiplicity of infection, which is based on titer and is subject to the same inaccuracies, AVC is based on the physicochemical parameters of the transduction assay and so is a more reliable alternative.

3T3 Cells↗
PubMed2000

Toward a more accurate quantitation of the activity of recombinant retroviruses: alternatives to titer and multiplicity of infection.

In this paper, we present a mathematical model with experimental support of how several key parameters govern the adsorption of active retrovirus particles onto the surface of adherent cells. These parameters, including time of adsorption, volume of virus, and the number, size, and type of target cells, as well as the intrinsic properties of the virus, diffusion coefficient, and half-life (t1/2), have been incorporated into a mathematical expression that describes the rate at which active virus particles adsorb to the cell surface. From this expression, we have obtained estimates of Cvo, the starting concentration of active retrovirus particles. In contrast to titer, Cvo is independent of the specific conditions of the assay. The relatively slow diffusion (D = 2 x 10(-8) cm2/s) and rapid decay (t1/2 = 6 to 7 h) of retrovirus particles explain why Cvo values are significantly higher than titer values. Values of Cvo also indicate that the number of defective particles in a retrovirus stock is much lower than previously thought, which has implications especially for the use of retroviruses for in vivo gene therapy. With this expression, we have also computed AVC (active viruses/cell), the number of active retrovirus particles that would adsorb per cell during a given adsorption time. In contrast to multiplicity of infection, which is based on titer and is subject to the same inaccuracies, AVC is based on the physicochemical parameters of the transduction assay and so is a more reliable alternative.

Animals↗
PubMed1976

Changes in liver function after different types of surgery.

Liver function tests carried out after minor surgical procedures, under anaesthesia lasting for 1 hr, showed no abnormalities. Tests after body surface operations under the same anaesthetic techniques showed transient derangements. After intra-abdominal procedures, liver dysfunction was more marked, although no patients with evidence of preoperative liver dysfunction or postoperative surgical complications were studied and none received blood transfusions. Measurements of the serum bilirubin concentration showed the most frequent abnormalities, but the pseudocholinesterase concentration decreased progressively after intra-abdominal surgery and b.s.p. retention increased significantly. Serum concentration of intracellular enzymes (LDH, s.g.o.t. and s.g.p.t.) increased within an hour of starting surgery, changes which were probably not related to liver function.

Adult↗