Search PubMed⌕ Search

Biomedical subjects

L Harris

Publications and source records attributed to L Harris.

At least 181 records · Page 10Linked to original sources
PubMed1982

Blood pressure and heart rate in patients with ischaemic heart disease receiving nifedipine and propranolol.

A randomised controlled crossover trial was performed to assess the anti-anginal effects of nifedipine and propranolol separately and together. The effects of these treatments on blood pressure and heart rate were assessed at rest and after the cold pressor and mental arithmetic tests. Nifedipine and propranolol together produced the greatest reduction in supine and erect systolic and diastolic blood pressures. Propranolol (480 mg daily) lowered resting systolic/diastolic blood pressures by 7/6 mm Hg and nifedipine (60 mg daily) lowered it by 10/8 mm Hg, while in the erect position the hypotensive effect of these agents averaged 9/8 mm Hg. During the cold pressor test propranolol lowered the maximum pressure by an average of 11/6 mm Hg and nifedipine by 19/10 mm Hg. For the mental arithmetic test, the results were 7/2 mm Hg and 16/7 mm Hg respectively. Propranolol (480 mg daily)reduced supine and erect heart rate by 19 and 25 beats/minute respectively, while nifedipine did not alter heart rate significantly. The favourable haemodynamic responses to nifedipine suggest that it may be of value in the management of hypertension.

Adult↗
PubMed1982

Calcium-channel blockers and beta blockers: advantages and disadvantages of combination therapy in chronic stable angina pectoris.

In electrophysiologic studies we have previously shown that the calcium-channel blockers nifedipine, verapamil, and diltiazem have different actions on the atrioventricular node: nifedipine has no evident effect at a dose of 7.5 micrograms/kg of body weight intravenously, whereas verapamil (0.15 mg/kg) and diltiazem (0.25 mg/kg) both prolong the AH interval significantly and terminate or slow reciprocating atrioventricular tachycardia involving the atrioventricular node alone or in association with an accessory pathway. None of the calcium-channel blockers tested influenced intraventricular conduction, but all increased the sinus rate. Since these properties suggested that it would be safer to combine nifedipine, rather than verapamil and diltiazem, with beta-adrenergic blockers in the treatment of ischemic heart disease, we tested this combination for efficacy and safety. Our previous results have now been reviewed, and they show that according to both subjective and objective criteria, nifedipine adds benefits to the action of propranolol in the management of chronic stable angina pectoris. No adverse effects were seen in our series, and beneficial influences were noted in patients with elevation of blood pressure. Side effects reported by others and said to arise from the interaction between nifedipine and beta blockers are analyzed, and prudence is suggested before the combination, or indeed any negative inotropic agent, is given to patients with impaired left ventricular function. The previous reports cannot be taken to indicate that nifedipine has a greater tendency to produce adverse effects in this combination than does the beta-adrenergic blocker.

Adrenergic beta-Antagonists↗
PubMed1982

Syncope in hypertrophic cardiomyopathy.

A patient with hypertrophic cardiomyopathy, syncope, and frequent ventricular tachycardia was monitored during a syncopal episode. An unrecordable blood pressure and the loss of a left ventricular outflow tract murmur without evidence of arrhythmia suggested a primary haemodynamic mechanism such as reduction in left ventricular volume.

Blood Pressure↗
PubMed1981

Nifedipine and propranolol: a beneficial drug interaction.

The antianginal effects of two active drugs, nifedipine and propranolol, alone in combination, were compared with those of placebo in a double-blind clinical trial that included 16 patients with chronic stable angina triggered by exertion. A low dose and a high dose of the active drugs were used (nifedipine, 30 and 60 mg/day; propranolol, 240 and 280 mg/day). Precordial exercise mapping and continuous electrocardiographic recordings were used to assess objective response to therapy, and the patients were asked to keep a diary of episodes of chest pain and consumption of nitroglycerin tablets for subjective appraisal. Both frequency of chest pain and nitroglycerin consumption were significantly reduced by each of the active drugs when compared with placebo, and the combination of nifedipine and propranolol added significantly to the effectiveness. Reductions in area of ischemia and number of episodes of ST segment depression on 48-hour ambulatory electrocardiographic monitoring corroborated the efficacy of each active treatment with respect to placebo. Nearly 60 percent of all episodes of ST segment depression were painless and responded to the active treatment in the same manner as did the episodes associated with chest pain. Side effects were mild and all treatments were well tolerated. The objective methods used allowed for clear-cut differentiation of treatment effects with the various regimens. Although the two drugs alone were significantly more effective than placebo, their combination provided an even greater improvement (p less than 0.005), and therefore it appears to be a safe and effective form of treatment for chronic stable angina.

Adult↗
PubMed1981

Thoracic aortic aneurysm causing acute bronchospasm.

Acute respiratory failure presenting as intractable bronchospasm was caused by tracheal obstruction due to an aneurysm of the thoracic aorta. Atropine was used successfully as a bronchodilating agent, as conventional therapy failed. The diagnosis was established by fiberoptic bronchoscopy.

Acute Disease↗
PubMed1980

Eye movement in strabismic cats.

Strabismus is a common clinical condition in which the visual axes of the eyes do not intersect on the object being viewed. As such, the ability to achieve single binocular vision by fusing the images of a single object in the two eyes is lost. In most cases of strabismus, one of the two eyes is clearly deviated and the other eye is used for fixation, although in some cases each eye is used alternately for fixation. While much attention has been devoted to the motor capabilities of the deviating eye in strabismus, little attention has been given to the visuomotor competence of the other eye. We report here that, if one eye of a kitten is made to deviate by surgery, the visuomotor capacities of the other, "normal", eye are affected. A reduction in the ability to follow the movement of a large striped drum is observed with binocular viewing, even when stimuli are viewed monocularly with the normal eye. This means that anomalous visual input from the deviated eye during stimulation is not the cause of the reduced oculomotor capacities.

Animals↗
PubMed1980

Preparation and properties of highly enriched cardiac sarcolemma from isolated adult myocytes.

Isolated myocytes were prepared from adult canine hearts using a combined technique of myocardial perfusion followed by incubation with collagenase. More than 60% of the cells routinely excluded trypan blue dye. Disruption of the myocytes was accomplished using high pressure nitrogen cavitation. After differential and sucrose gradient centrifugation, the peak sarcolemmal fraction averaged 100-fold enrichment in ouabain-inhibited K+-stimulated p-nitrophenyl phosphatase and 82-fold in ouabain-inhibited (Na+,K+)-ATPase. These sarcolemmal membranes are enriched in phospholipid phosphorus (1.98 mumol/mg of protein) and more than 4-fold in sphingomyelin and cholesterol. Polyacrylamide gels revealed three major protein peaks at 50,000, 91,000, and 140,000 apparent molecular weights. This work demonstrates the feasibility of preparing highly pure cardiac sarcolemma from isolated adult myocytes. The problem of cellular cross-contamination due to heterogeneity of cell types in whole myocardial tissue has been circumvented. The level of enrichment exceeds all reported preparations of cardiac sarcolemma from whole myocardium and cultured myocytes. This preparation should prove to be useful as an in vitro model for studies of physiological, pharmacological, and pathological perturbations of sarcolemmal structure and function.

4-Nitrophenylphosphatase↗
PubMed1980

Analysis of a paradoxical logic: a case study.

A case study of a normally functioning married couple was conducted to investigate the relation between their logic and their communication patterns. Two communication theories, the Interactional View and the Coordinated Management of Meaning, were employed in an analysis of the couple's logic and communication. A triangulated methodology, consisting of interviews, written self-reports, and role-playing, was used to elicit the couple's constitutive and regulative rules. The discovery of paradoxical rules led to several propositions concerning the circular relation between communication and socially created realities. Specifically, the analysis revealed paradoxical rules associated with restricted episodes in which the couple could not obtain their goal of eliminating conflict.

Communication↗
PubMed1979

Separation and purification of a potent bactericidal/permeability-increasing protein and a closely associated phospholipase A2 from rabbit polymorphonuclear leukocytes. Observations on their relationship.

Two antibacterial proteins from rabbit polymorphonuclear leukocytes, a potent bactericidal cationic protein that increases the envelope permeability of susceptible gram-negative bacteria and a phospholipase A2, have been purified to near homogeneity by ion exchange, gel filtration, and hydrophobic interaction chromatography. The apparently noncatalytic bactericidal/permeability-increasing protein has an approximate molecular weight of 50,000 and is isoelectric at pH 9.5 to 10.0. The molecular properties, including amino acid composition, and the antibacterial potency and specificity of this rabbit leukocyte protein and of the bactericidal/permeability-increasing protein from human granulocytes that we have recently purified (J. Biol. Chem. 253, 2664-2672, 1978) are closely similar. Both proteins kill several strains of Escherichia coli and Salmonella typhimurium. Rough strains are more sensitive than smooth strains. All gram-positive bacterial species tested are insensitive to high concentrations of either rabbit or human protein. The phospholipase A2, purified by hydrophobic interaction chromatography on phenyl-Sepharose, ran as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent molecular weight of 14,000 and had a specific enzymatic activity comparable to that of purified phospholipases A2 from other sources. Separation of the phospholipase A2 from the bactericidal/permeability-increasing protein has no noticeable effect on the bactericidal and permeability-increasing activities of the purified bactericidal protein, but removes the ability of the phospholipase A2 to hydrolyze the phospholipids of intact Escherichia coli. Upon recombination of the phospholipase A2 with the bactericidal/permeability-increasing protein, the phospholipase A2 regains its activity toward the phospholipids of intact E. coli suggesting that these two antibacterial leukocyte proteins act in concert.

Amino Acids↗