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Biomedical subjects

J A Mackay

Publications and source records attributed to J A Mackay.

7 recordsLinked to original sources
PubMed1996

The hypertension trials.

ESTABLISHED ANTIHYPERTENSIVE TREATMENT: Previous studies have clearly demonstrated the benefits of antihypertensive therapy, particularly in reducing the incidence of stroke. However, there is still concern that the full potential for reversing coronary heart disease in the hypertensive patient has not been realized by treatment with established agents, the diuretics and the beta-blockers. TRIALS ON NEWER AGENTS: A question that still remains to be answered is whether treatment regimens based on alternative drugs, including calcium channel blocking agents and angiotensin converting enzyme inhibitors, will confer an advantage over older drugs. This question is at last being addressed in long-term morbidity and mortality trials with these newer agents.

Antihypertensive Agents↗
PubMed1996

Calcium channel blockers in the dock: innocent or guilty?

Several studies have recently been published which have raised doubts over the long-term safety of calcium channel blockers (CCB). These have included retrospective case control studies in hypertension and meta-analyses of small scale studies in unstable angina and myocardial infarction (MI). Most of the reports were primarily concerned with the use of the short acting dihydropyridine nifedipine. Despite wide media coverage of these reports, the results are by no means irrefutable and, because of the nature of the studies themselves, are open to several criticisms. Calcium channel blockers are currently being evaluated in large-scale, prospective, randomised controlled studies, but results are unlikely to be available within the next few years. Meanwhile, the consensus view seems to be that short acting dihydropyridines should in general be avoided and have no place in the management of unstable angina and post MI. In the setting of stable angina, long acting dihydropyridines should generally be used in conjunction with a beta-blocker. In hypertensive patients, long acting dihydropyridines may be used as alternative antihypertensive agents in patients in whom the first line agents (diuretics and beta-blockers) are poorly tolerated, contra-indicated or ineffective.

Calcium Channel Blockers↗
PubMed1987

Autosomal recessive juvenile cataract in Hutterites.

Autosomal recessive inheritance of juvenile cataract is described amongst several related sibships of Lehrerleut Hutterites. The main features of the cataract include onset between three and seven years of age; rapid progression to maturity within one to three months; normal intelligence; no systemic associations, and no urinary reducing substances and normal erythrocyte galactokinase activity. Genetic analysis demonstrates the close relationship between parents of affected sibships with a coefficient of inbreeding of affected sibships of 0.0512. Estimates of heterozygote frequency within Lehrerleut Hutterites at 0.128 indicate that if current inbreeding practice continues additional cases can be expected.

Alberta↗
PubMed1986

The requirements for transferrin-dependent adherence of human granulocytes to pollen grains.

Human granulocyte/pollen binding protein (GPBP), previously identified as serum transferrin, promoted prolonged firm adherence of neutrophils to Timothy grass pollen. Some characteristics of this adherence reaction are reported. GPBP-induced binding was time-, temperature- and concentration-dependent. Maximal adherence was observed by 2 h and was only slightly decreased at 18 h. The optimal temperature for adherence was 37 degrees C. Concentrations of GPBP as low as 1.25 microgram/ml gave significantly greater binding than the albumin or lactoferrin control. Eosinophils, monocytes and lymphocytes did not appear to participate in GPBP-induced pollen binding reactions at concentrations up to 300 micrograms/ml. In the presence of GPBP, neutrophils adhered to a range of grass, weed and tree pollens. These included timothy, meadow, false oat, rye, giant and short ragweed, plantain, silver birch and ash. GPBP did not facilitate the adherence of granulocytes to inert particles of similar size such as Sephadex beads and agarose. The adherence was Mg++- but not Ca++-dependent and was not inhibited by a monoclonal antibody to the transferrin receptor (OKT9). Transferrin/GPBP did not bind to either neutrophils or pollen grains. A purified commercial transferrin reacted in all respects like GPBP in these pollen binding studies. These observations indicate that GPBP/transferrin-induced adherence of granulocytes to pollen grains is a hitherto unrecognized property of transferrin which appears unrelated to iron transport or the conventional transferrin receptor.

Antibodies, Monoclonal↗
PubMed1986

Enhancement of leukocyte cytotoxicity after exercise-induced asthma.

We have previously shown that there were elevations of neutrophil chemotactic activity (NCA) and increases in the percentages of neutrophil and monocyte complement rosettes after exercise-induced asthma (EIA). These observations suggested that leukocyte activation may occur after EIA, possibly as a result of the release of mast-cell-associated mediators. In the present study, we have attempted to establish whether neutrophils and monocytes are functionally altered after EIA as assessed by changes in their cytotoxic capacity. Cytotoxicity was assessed by a direct visual killing assay using opsonized (complement-coated) schistosomula of Schistosoma mansoni as target organisms. Neutrophils and mononuclear cells obtained from 8 patients after exercise-induced asthma (EIA+ve) had increased cytotoxicity for opsonized schistosomula for as long as 60 min after exercise. These changes were preceded by elevations in the concentrations of serum high molecular weight NCA (which were maximal at 10 min after exercise). In asthmatic patients who did not develop exercise-induced asthma (EIA-ve), no significant increases in neutrophil or mononuclear cell killing of schistosomula, or serum NCA concentrations, were observed. There was a highly significant correlation (p less than 0.001) between the reduction in FEV1 and the increases in neutrophil cytotoxicity. In 5 EIA+ve patients, administration of disodium cromoglycate (cromolyn) prior to the exercise task inhibited both the enhancement in neutrophil and mononuclear cell cytotoxicity, as well as the elevations in circulating NCA and the reductions in FEV1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Human granulocyte/pollen-binding protein. Recognition and identification as transferrin.

Normal human serum was found to contain a heat-stable protein which promoted the binding of granulocytes to timothy grass pollen (granulocyte/pollen-binding protein [GPBP]). GPBP was purified by gel filtration, anion exchange, and affinity chromatography. Virtually all of the granulocyte/pollen-binding activity was associated with a beta-1-protein having a molecular mass of approximately 77,000 D and an isoelectric point of between 5.5 and 6.1. By immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein was identified as transferrin. Monospecific antisera raised against either GPBP or transferrin removed biological activity from GPBP preparations, and GPBP and transferrin gave lines of identity with these two antisera. The apparent heterogeneity in the molecular size and charge of GPBP observed during progressive purification was minimal when GPBP was saturated with ferric ions before the separation procedures. These experiments indicate that granulocyte/pollen binding is a hitherto unrecognized property of transferrin which appears to be unrelated to iron transport and raises the possibility that transferrin might have a physiological role in the removal of certain organic matter.

Carrier Proteins↗