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Biomedical subjects

E M Williams

Publications and source records attributed to E M Williams.

At least 73 records · Page 4Linked to original sources
PubMed1980

Adaptation of hypertensives to treatment with cardioselective and non-selective beta-blockers. Absence of correlation between bradycardia and blood pressure control, and reduction in slope of the QT/RR relation.

Thirty mild hypertensives were treated for more than two months with either cardioselective (atenolol or metoprolol) or non-selective (propranolol or pindolol) beta-blockers; the patients were assigned to the drugs in a double-blind manner. A procedure was designed to distinguish between the effects of the drugs themselves while treatment continued, and the development of adaptive changes which would persist when the drugs had been eliminated from the body. Though individual responses to treatment varied in both groups, the mean effect of the cardioselective and non-selective drugs in the control of hypertension was similar. There was no evidence of the development of supersensitivity or "rebound". On the contrary, an adaptive bradycardia (that is a fall of not less than 10% in heart rate persisting 52 hours after stopping treatment) was observed at rest in 17/30 patients, and peak heart rates and blood pressures during exercise were lower in both groups than before treatment. Cardioselective drugs induced a significantly greater bradycardia at rest than non-selective, but on exercise increases in heart rate were reduced more by the non-selective drugs, so that the same peak heart rates were reached on exercise in both groups. Adaptation also affected QT. The results suggest that two factors govern the shortening of QT by increases in heart rate, a "metabolic" effect, determined by sympathetic drive, and a "biophysical" effect determined by heart rate. The adrenergic effect is attenuated by acute beta-blockade, or by adaptation to prolonged blockade, leaving a shallow, rate-determined, slope to the QT/RR regression.

Adaptation, Physiological↗
PubMed1980

Down syndrome and maternal age in South Glamorgan.

Seventy cases of Down syndrome have been ascertained in South Glamorgan during the period 1968 to 1976. This gives an overall incidence of 1 in 658 live births. Analysis of the data on the basis of single years of maternal age gives an incidence of 1 in 200 by 36 years, 1 in 100 by 40 years, and 1 in 50 by 44 years. All incidence figures are for live births at age of delivery.

Adolescent↗
PubMed1978

Fibronectin concentration is decreased in plasma of severely ill patients with disseminated intravascular coagulation.

Plasma fibronectin (cold-insoluble globulin) is known to be cross-linked to fibrin during the final stage of blood coagulation and is probably the major nonspecific opsonin of blood. We measured the concentration of plasma fibronectin in 36 hospitalized patients (11 with malignancy, 12 with infection, 13 with other underlying diseases) with evidence of fibrin depostion and lysis. Plasma fibronectin concentration was greater than 2 S.D. below the mean of normals in 17 of the patients (p less than 0.001). Depression of fibronectin was not related to severity of disseminated intravascular coagulation, as assessed by fibrinogen concentration and the quantity of FDP in serum. Depressed plasma fibronectin concentration and the quantity of FDP in serum. Depressed plasma fibronectin concentration was an unfavorable prognostic finding, inasmuch as 12 of the 17 patients with depressed fibronectin concentrations died during hospitalization as compared to five of the 19 patients with normal fibronectin concentrations (p less than 0.02). We speculate that specific depletion of plasma fibronectin, because of codeposition with fibrin or due to increased utilization as a nonspecific opsonin, may contribute to the organ failure seen in severely ill patients.

Adult↗
PubMed1977

Morphometric changes in rabbit ventricular myocardium produced by long-term beta-adrenoceptor blockade.

In rabbits long-term beta-adrenoceptor blockade did not cause any change in the morphology of individual organelles in the ventricular myocardium. There were, however, striking and significant changes in their relative distribution: (1) the relative volume of the mitochondria was reduced and was replaced by an equivalent relative increase in sarcoplasm; and (2) the relative volume of vascular elements was increased and the interfibrillar volume was decreased, so that the path from capillary to cell wall was reduced. The relative volumes of myofibrils and nuclei were unchanged. The doses used were well within the range used clinically, so that the results could be relevant to the efficacy of beta-blockers in angina pectoris, because the relative increase in capillaries and shorter diffusion pathway for oxygen could raise oxygen availability. The reduced rate of growth of the heart in young rabbits during beta-blockade may also be relevant to the treatment of infants with hypertrophic obstructive cardiomyopathy by beta-blockers.

Animals↗
PubMed1977

The effect on atrial and ventricular intracellular potentials, and other pharmacological actions of L9146, a non-halogenated benzo(b)thiophene related to amiodarone.

L9146 was synthesised in the hope of eliminating the unwanted side-effects of amiodarone which has been shown to be effective in the control of atrial fibrillation, flutter, and in pre-excitation syndromes such as Wolff-Parkinson-White syndrome. L9146 has pharmacological and electrophysiological effects similar to those of amiodarone. It is an antagonist of both alpha and beta adrenoceptor-mediated cardiovascular effects of a noncompetitive type. It lowers vascular resistance briefly, and causes a longer lasting bradycardia. It moderately reduces the maximum rate of depolarisation (MRD), conduction velocity, and totally suppresses ventricular pacemakers activated by high doses of isoprenaline. In addition, L9146 greatly prolongs action potential duration (APD) in atrial and ventricular muscle. In normal ventricular conducting tissue the action potential duration (APD) is shorter in the bundle of His than in the false tendons, and shorter still in the ventricular muscle. L9146 lengthened APD throughout, but particularly in the proximal portion, and even more in the muscle, so that APD became uniform. The decrement of conduction of premature action potentials was increased to the point at which slowly conducting premature AP's were eliminated altogether.

Action Potentials↗
PubMed1977

Genetic study of Welsh gypsies.

A South Wales gypsy kindred of Romany origin had a high incidence of phenylketonuria along with other recessively inherited disorders. There was a high degree of consanguinity (F = 0-017) with an excess of non-specific mental subnormality among known consanguineous matings. Phenylketonuria and a number of other recessively inherited disorders have been recorded from other Romany gypsy populations, but it is uncertain whether this results from a generally high gene frequency for the disorders or from consanguinity and other more local factors.

Adult↗
PubMed1977

Genetic markers in Welsh gypsies.

Data are presented on polymorphic genetic markers of 84 Welsh gypsies, members of an inbred population characterised by a high incidence of phenylketonuria and other recessively inherited diseases. Sixteen polymorphic loci were studied: the ABO blood group distribution was comparable to that of the surrounding population, the B gene frequency being 7-5%, a lower frequency than most earlier studies in gypsies. The haptoglobin 1 gene frequency (23-7%) was very different from that of the British population, resembling the frequency found in India and some previously reported gypsy groups. The data on Welsh gypsies for the various loci are discussed in relation to the known evidence for a number of European gypsy populations, and in relation to the genetic structure of these populations. It is concluded that genetic divergence has occurred in the European gypsies, and that this may have been accentuated by the dispersal, isolation, and inbreeding which have occurred during the present century.

ABO Blood-Group System↗
PubMed1975

The effects of prolonged beta-adrenoceptor blockade on heart weight and cardiac intracellular potentials in rabbits.

Estimates were made in vivo in rabbits of the relative beta-receptor blocking potency and duration of action of propranolol and practolol. In further experiments groups of litter mates were injected twice daily with approximately equi-active amounts of propranolol or practolol, or with saline, for several weeks. The heart weights of the treated animals were significantly lower than those of the controls, the water contents were higher, and the dry weight differences were highly significant; -16.8% after 2 mg/kg bd propranolol for six weeks and -33.8% after 10 mg/kg practolol. (The treated animals grew less rapidly than the controls; when corrected for body weight these figures were -11.9% and -20.4%, respectively.) In the practolol group, but not the propranolol group, the duration of the atrial intracellular potentials was prolonged. There was no evidence that the prolonged treatment with either drug had a negative inotropic effect, or reduced positive inotropic responses to isoprenaline.

Animals↗