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Biomedical subjects

M McKinnon

Publications and source records attributed to M McKinnon.

30 records · Page 2Linked to original sources
PubMed1995

Soluble interleukin-5 receptor alpha-chain binding assays: use for screening and analysis of interleukin-5 mutants.

Interleukin-5 (IL-5) is a key cytokine for the production, differentiation, and activation of eosinophils. IL-5 is a member of the four helical bundle family of cytokines, and in common with many members of the cytokine family it binds to a heterodimeric receptor composed of a ligand binding alpha-chain and a signal-transducing beta-chain. We have established two receptor/ligand binding assays based on the extracellular domain of the receptor alpha-chain which we have produced as a fusion protein. One assay is based on scintillation proximity fluoromicrospheres and radiolabeled ligand and the other on detection of biotinylated ligand binding to immobilized receptor using a chemiluminescent substrate in a 96-well microtiter plate format. Both receptor binding assays have been optimized for high throughput screening for receptor antagonists. These assays were also used for analytical purposes and the binding of ligand to the receptor alpha-chain was compared directly to receptor binding assays performed on TF-1 cells which express the receptor alpha beta-heterodimer. These three assays have been used to study site-directed mutants of IL-5 to determine the important residues for interaction of the cytokine with each chain of the receptor (P. Graber et al. (1995) J. Biol. Chem. 270, 15762-15769).

Animals↗
PubMed1995

Identification of key charged residues of human interleukin-5 in receptor binding and cellular activation.

Interleukin-5 (IL-5) is a cytokine that plays a major role in the differentiation and activation of eosinophils. In order to identify which charged residues of human IL-5 are important in binding to its receptor and subsequent cellular activation, we have systematically replaced all of the clusters of charged amino acids with alanine residues. The mutants have been expressed in Escherichia coli, renatured, and purified. They were assayed for ability to cause proliferation of the erythroleukaemic cell line TF-1 and the up-regulation of eosinophil adhesion to ICAM-1. In addition, we studied receptor binding using either immobilized recombinant IL-5 receptor alpha-chain or the alpha/beta-receptor complex expressed on TF-1 cells. The key charged residue involved in binding to the beta-chain of the receptor is Glu-12. This residue is in an identical position to those previously identified in IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) involved in binding to the receptor beta-chain. The alpha-chain binding site is shown to involve the side chains Arg-90 and Glu-109, located in the second beta sheet and after the end of the fourth helix, respectively. It is unique to IL-5 and does not occur in IL-3 or GM-CSF. Understanding the topology of the interaction of IL-5 with its receptor chains will help in the search for rationally designed antagonists of IL-5 function.

Amino Acid Sequence↗
PubMed1995

Does the Hawksley random zero sphygmomanometer underestimate blood pressure, and by how much?

The study objective was to compare blood pressure (BP) measurement by the Hawksley random-zero sphygmomanometer and the standard mercury sphygmomanometer. Comparison of simultaneous 'blind' BP measurements were made using the Hawksley random-zero sphygmomanometer and the standard mercury sphygmomanometer linked by a Y-connector to a single cuff, in the general practice and office environments. Sixty five healthy volunteers and general practice patients, aged between 20 and 50 years (SBP range 82-184 mm Hg, DBP range 38-112 mm Hg), were studied. Each had three blood pressure measurements taken. Mean BPs recorded by the Hawksley random-zero sphygmomanometer were lower than those recorded by the standard mercury sphygmomanometer. The Hawksley random-zero sphygmomanometer underestimated SBP by 1.3 mm Hg (95% CI 0.9-1.8 mm Hg) and DBP by 1.7 mm Hg (95% CI 1.1-2.3 mm Hg). These differences between instruments were independent of BP level both for systolic and diastolic measurements. An overview including this study and six other published reports describing nine studies examining the performance of the Hawksley random-zero sphygmomanometer suggested a similar degree of underestimation for SBP (mean difference 1.35 mm Hg, 95% CI 1.24-1.46 mm Hg). Underestimation of DBP appeared greater (mean difference 2.54 mm Hg, 95% CI 2.43-2.65 mm Hg) but was reduced when two outlying studies were removed from analysis (mean 1.97, 95% CI 1.85-2.09 mm Hg). We conclude that the Hawksley random-zero sphygmomanometer underestimates systolic and diastolic pressure, when compared with the standard mercury sphygmomanometer. However, the degree of underestimation is small and appears consistent across a wide range of blood pressure levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Phospholipase-D activation can be negatively regulated through the action of protein kinase C.

Transient activation of COS-1 cell phospholipase-D (PLD) in response to the protein kinase C (PKC) agonist tetradecanoyl phorbol acetate (TPA) was demonstrated by monitoring the ethanol-dependent accumulation of phosphatidylethanol (PtdEth). Transfection of COS-1 cells with PKC-alpha (wild type and constitutively activated mutants) produced no detectable ptdEth on incubation of transfected cells in the presence of ethanol. However, the response of transfected cells to subsequent TPA stimulation was inhibited, consistent with a role for the PKC-alpha in the suppression of PLD activity.

Animals↗
PubMed1994

A comparison of demethoxyviridin and wortmannin as inhibitors of phosphatidylinositol 3-kinase.

The mammalian Ptdlns 3-kinase is shown to be inhibited by low nanomolar concentrations of demethoxyviridin, an antifungal agent structurally related to wortmannin. The inhibitory potency of both compounds could be observed in purified Ptdlns 3-kinase whether or not the regulatory subunit (p85 alpha) was present, suggesting that the inhibitors bind to the catalytic subunit (p110) of the Ptdlns 3-kinase. These inhibitors also show similar potency against the intrinsic p85-phosphorylating activity of the p110-kinase. However, the structurally related Ptdlns 3-kinase from Saccharomyces cerevisiae (Vps34p) is not inhibited by either compound. Both inhibitors target the mammalian Ptdlns 3-kinase in vitro and in vivo, implying that these compounds should be useful in suppressing Ptdlns 3-kinase in mammalian systems. The inhibitors did not affect the mammalian Ptdlns 4-kinase, but they are able to inhibit a membrane-associated Ptdlns 4-kinase from Schizosaccharomyces pombe.

Androstadienes↗
PubMed1994

Hospital admissions and social deprivation of patients with diabetes mellitus.

This study examined the relationship between hospital admissions for patients with diabetes mellitus and residence in an area of social deprivation. Admissions of patients with diabetes mellitus were identified during a 5-year period between 1987 and 1992 using the district patient information service. All persons admitted were assigned to an electoral ward on the basis of their postcode. Age standardized admission rates were compared to the Townsend Deprivation Score for each electoral ward. A positive correlation was found between age standardized admission rate and Townsend Score (r = 0.76, p < 0.001). We believe this has significance for planning health care resources.

Diabetes Mellitus↗
PubMed1985

Midline cervical cleft.

Midline cervical cleft is a rare congenital anomaly of the ventral neck. A series of 12 cases of midline cervical clefts over a 30-year period is reported. This anomaly is part of a spectrum of midline branchiogenic syndromes resulting from abnormal migration of cells derived from the branchial arches. The preferred operative correction requires complete excision of the cleft with its underlying fibrous cord and closure with multiple Z-plasties.

Child, Preschool↗
PubMed1979

Geographic distribution of peptic ulcer disease in Western Samoa.

A survey of peptic ulcer disease in Western Samoa is described. As compared with New Zealand experience, an unusually high prevalence of peptic ulceration is documented. A remarkable and significant variation in the geographic distribution of cases is reported. Regions of high prevalence were significantly associated with disease onset at an earlier age and with increased frequency of a family history of ulcer disease. It is concluded that this genetic predisposition is unlikely to sufficiently account for the regional localisation of cases observed and environmental causes are under study.

Adolescent↗