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Biomedical subjects

D T Wilson

Publications and source records attributed to D T Wilson.

16 recordsLinked to original sources

Abolition of electrocardiographic pattern of left ventricular aneurysm by posterior myocardial infarction.

We report a patient who presented with prominent gastrointestinal symptoms in whom a confident clinical diagnosis of acute posterior myocardial infarction was facilitated because the fresh electrocardiographic changes of true posterior myocardial infarction abolished the old pattern of left ventricular aneurysm. This interesting electrocardiographic phenomenon has not, to our knowledge, been previously reported.

Electrocardiography

Detection of high-risk groups and individuals for periodontal diseases: laboratory markers from analysis of gingival crevicular fluid.

Gingival crevicular fluid is regarded as a promising medium for the detection of markers of periodontal diseases activity. The collection protocols are straight forward and non-invasive and can be performed at specific sites of interest in the periodontium. Because the fluid accumulates at the gingival margin, it will contain potential markers derived not only from the host tissues and serum but also the subgingival microbial plaque, and thus an extremely broad range of candidate molecules may be investigated. However, the ability to successfully describe indicators of current disease activity and predictors of future disease is dependent not only upon the choice of the biochemical marker but also on the accurate description of the health status of the sample sites using currently available clinical and radiographic methods. Areas of study which currently show the most promise involve the analysis of host enzyme activities directed against components of the extracellular matrix, the nature of the glycosaminoglycans released into the sulcus and the concentration in gingival crevicular fluid of certain mediators of the inflammatory process, most notably prostaglandin E2.

Disease Susceptibility

Detection of high-risk groups and individuals for periodontal diseases: laboratory markers from analysis of saliva.

The use of saliva as a source of components that may identify subjects at risk of developing destructive periodontitis, or provide markers of disease potential or activity, has been reviewed. It was concluded that bacteria, their constituents or products are unlikely to be rewarding and that host-derived salivary factors such as enzymes cannot identify risk, as deficiency states for these do not exist. Secretory IgA, plasma IgA and IgG isotype levels and specific antibodies may be associated with risk, but probably only if levels fall below those which are protective or a specific antibody response is absent. More work is needed to distinguish between monomeric and dimeric IgA antibodies and to identify IgG antibodies in longitudinal clinical studies. In general, although saliva may prove to be useful as a source of indicators of current disease activity or as a means of assessing responses to treatment, it is unlikely to provide evidence for the existence of risk factors.

Biomarkers

Cloning and characterization of the genes for the two homocysteine transmethylases of Escherichia coli.

We have cloned the genes for the two homocysteine transmethylases of Escherichia coli K12. The vitamin B12-independent enzyme is encoded by the metE gene while the metH gene codes for the vitamin B12-requiring enzyme. Overexpression of the gene products and Tn1000 mutagenesis have enabled the metE and metH gene products to be identified as 99 kDa and 130 kDa polypeptides, respectively. The truncated polypeptides generated by Tn1000 insertion were used to determine the direction of transcription of the metE and metH genes. Negative complementation suggests that the MetH enzyme exists as an oligomer. Investigation of the expression of the chromosomal- and plasmid-encoded gene products confirms that metE is subject to negative control by vitamin B12 and methionine, and that metH is under positive control by the cofactor and negative control by methionine. For vitamin B12 and methionine to act as regulatory effectors in metE control, functional metH and metJ genes are required, respectively. The use of stable Tn1000-generated fragments of the metE product as electrophoretic markers for the plasmid-encoded metE gene product demonstrated that the two regulatory proteins involved in negative control of metE are present in excess. Under conditions whereby both forms of negative metE control are non-functional, the metE gene product represented about 90% of the total protein, and cell growth was severely impaired.

Cloning, Molecular

Detection of high-risk groups and individuals for periodontal diseases. Systemic predisposition and markers of general health.

The evidence for systemic predisposition to periodontal diseases is reviewed in relation to cellular and humoral immunity, drug therapy, diet and nutrition and stress. It is concluded that, apart from defects of polymorphonuclear leukocytes (PMN) and Ehlers-Danlos Syndrome, little firm evidence exists for other diseases, though insulin-dependent diabetes and acquired immune deficiency syndrome (AIDS) may accelerate and/or potentiate the damage of existing disease. The precise rôle of drugs, diet and nutrition and stress remain to be elucidated, but recent advances in these areas offer the prospect of assessing risk using carefully controlled studies.

Acquired Immunodeficiency Syndrome

Detection of high-risk groups and individuals for periodontal diseases. Evidence for the existence of high-risk groups and individuals and approaches to their detection.

It is argued that the periodontal diseases can no longer be regarded as universally prevalent conditions to which all members of the world's population are at equal risk if they fail to practise good oral hygiene. Rather, they should be regarded as a range of different diseases for each of which certain individuals, which together comprise certain minority groups, are at relatively high risk. The epidemiological evidence for the existence of high-risk groups is reviewed, from which it is concluded that world-wide the prevalence of severe destructive periodontitis is of the order of only 7-15% of the adult dentate population. A working classification of the different types of gingivitis and periodontitis is offered, as is a summary of the theoretically possible approaches to the detection of high-risk groups and individuals which are explored in detail in subsequent papers. Successful identification of such individuals will permit scientifically valid, rational and targetted prevention and treatment.

Adult

Detection of high-risk groups and individuals for periodontal diseases. Clinical assessment of the periodontium.

The fundamental concepts of measuring periodontal diseases and the interpretation of such information as an historical record of disease, rather than disease activity, emphasises the need for improved diagnostic and prognostic tests. Criteria for an indicator of disease activity were suggested and an index fulfilling these should allow sites to be categorised as "active", quiescent or healing, and enable one to predict the risk of future disease activity. The ability of current measurements and indices, routinely used during clinical assessments of periodontal diseases, to fulfill the suggested criteria was considered and rejected in all cases. It is concluded that clinical parameters are only capable of identifying disease retrospectively, indicating the need for longitudinal, rather than cross-sectional studies in the search for clinical and laboratory markers of disease activity and susceptibility.

Gingival Crevicular Fluid

Platelet aggregation and plasma lipoproteins in alcoholics during alcohol withdrawal.

Platelet aggregation, platelet lipid composition and plasma lipoprotein concentrations were measured each week in a group of seventeen alcoholics, without overt liver disease, for one month, following acute, total alcohol withdrawal. The platelets were initially hypoaggregable but, within 1-2 weeks of cessation of drinking, they became hyperaggregable and then gradually returned towards normal values. Hyperaggregability could not be explained by increases in either the cholesterol or the arachidonic acid content of the platelets. Plasma very-low-density lipoprotein cholesterol levels remained high throughout the study, but the initially raised levels of high-density lipoprotein (HDL) cholesterol fell by 26%. Low-density lipoprotein (LDL) cholesterol concentration rose by 10% after two weeks of withdrawal but then returned to about the starting level. The resulting changes in the plasma LDL-cholesterol:HDL-cholesterol ratio, which had increased by more than 50% after two weeks of abstinence, essentially paralleled the time course of enhanced platelet reactivity in all but four of the alcoholics. These findings suggest that alterations in plasma lipoprotein concentrations during acute alcohol withdrawal may be a contributory factor to the haemostatic disorders present in such patients.

Adult