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Biomedical subjects

D Cameron

Publications and source records attributed to D Cameron.

At least 55 records · Page 3Linked to original sources

John Snow, the broad street pump and modern epidemiology.

John Snow was a genius in epidemiology. His achievement was to evolve an elegant, internally and externally consistent theory which concerned the mechanisms and processes involved in every aspect of the subject he had chosen to study. In order to do this he did not restrict himself to any method. He used all skills available to himself and his colleagues. He published his theory, and practical suggestions for the prevention of cholera arising out it, both internally in medical meetings and to the medical press, and to the public in the form of pamphlets and in reports addressed to the appropriate authority. This surely should be the objective of all epidemiological work.

Cholera

On line (real time) quantitative measurement of premature ventricular beats.

A real time system for graphically displaying premature ventricular beat trends is described. The system consists of analog detector circuits coupled to a Fortran based software program for premature ventricular beat processing. The software program runs four independent channels and has three available analysis modes: a "counting" mode which provides a running total of counts to date; an "averaging" mode which displays average number of events over time, and a "ratio" mode which provides an output reflecting changes in the ratio of premature ventricular beats to all beats. Various scale factors can be applied to accommodate differing background states. The system's strengths lie in its simplicity, accuracy, and simultaneous analog display of both the original ECG signal as well as the derived quantitative data.

Cardiac Complexes, Premature

Initial experience with universal pacemakers.

Thirty-five patients were implanted with the Sequicor DDD pacemaker between September 1, 1981 and March 1, 1982. The mean age was 61.7 years (range, 17-88). According to their ECGs, the patients fell into two distinct groups--those with A-V block and those with sick sinus syndrome. Our initial experience has indicated an excellent electronic component function (except for 1 discrepant reed switch); high battery drain of the Sequicor; complications similar to those seen with DVI or VVI pacing; and an increase in the hemodynamic benefits resulting from DDD as compared to DVI or VVI pacing in 70% of patients.

Adolescent

Interactions between the autonomic nervous system and tachycardias in man.

We have endeavoured to present an integrated and dynamic overview of the interaction between the autonomic nervous system and cardiac arrhythmias. Our purpose was not to be comprehensive, detailed, or all inclusive but to present a clinically relevant summary of some of the areas where autonomic tone may be pertinent. Clearly, most arrhythmias are not the result of a primary autonomic nervous system disorder. However, subtle and overt alterations in autonomic tone, interacting with rate, pressure, cardiac volume, contractility, and the intrinsic myocardial electrophysiologic properties likely exert a critical influence on many cardiac arrhythmias. We wish to emphasize that autonomic effects may be temporarily concealed or overwhelmed during certain states or by the administration of drugs. However, the modulating role of neural tone and neurotransmitters is almost always present, contributing significantly to the outcome of therapy.

Anti-Arrhythmia Agents

Radiology of sigmoid volvulus.

Sigmoid volvulus is often a surgical emergency. The diagnosis is usually reached on the basis of both clinical and radiologic assessment. A review of the radiologic findings in 20 patients diagnosed as having sigmoid volvulus is presented. Typical radiographic features are illustrated. Reasons for their absence in certain cases are discussed. [Key words: Volvulus, sigmoid; Diagnostic problems; Sigmoid, volvulus].

Barium Sulfate

Rate of onset of drunkeness. A preliminary study.

Of eight moderate drinkers drinking until they became intoxicated, four left relatively sober prior to a rapid increase in sensations of intoxication, and four experienced a gradual progression to intoxication.

Adult

Recruitment of problem drinkers.

As the first phase of a project designed to institute controlled drinking as a therapeutic goal for alcoholics, it was decied to recruit volunteers who were dissatisfied with their present mode of drinking but who had not previously sought help. This was done by requesting them to phone a private number. When these volunteers had been recruited it was proposed to modify their drinking habits to their own requirements, using non-averse training, drinking practice and ongoing group psychotherapy. This project however has not been implemented because of paucity of volunteers. The methods of recruitement are listed and those drinkers who volunteered are described. The reasons for the low rate of response are discussed.

Adult

Isolation of myotoxic component from rattlesnake (Crotalus viridis viridis) venom. Electron microscopic analysis of muscle damage.

The pathogenesis of myonecrosis induced by a purified component of rattlesnake (Crotalus viridis viridis) venom was studied at the light and electron microscopic levels. Crude venom was fractionated by gel filtration (Sephadex G-50) followed by cation exchange chromatography (Sephadex C-25). Electrophoretic homogeneity of the isolated myotoxin (Fraction II from C-25 column) was demonstrated in isoelectric focusing and disc gel polyacrylamide gel electrophoresis. White mice were injected intramuscularly with 1.5 mug/g of the purified protein in 0.1 ml of physiologic saline. Light microscopic examination of injected muscle revealed a series of degenerative events including partial vacuolation of muscle cells at 6, 12, and 24 hours and complete vacuolation and loss of striations at 48 and 72 hours. Hemorrhage was not observed. At the electron microscopic level the perinuclear space and sarcoplasmic reticulum were dilated in all samples. By 48 and 72 hours the myofibrils lacked striations and the sarcomeres were disorganized. Plasma membranes and T tubules remained intact in all samples. These results correlated well with the myonecrosis induced by crude Crotalus viridis viridis venom except for several important aspects. The pure component altered skeletal muscle cells specifically, with the sarcoplasmic reticulum being the primary site of action.

Animals

Immunochemotherapy of cancer with chlorambucil-carrying antibody.

Cell-surface localizing heterologous antibodies against the mouse EL4 lymphoma and a human malignant melanoma could be bound to chlorambucil without causing the loss of the alkylating activity of chlorambucil or interfering with the reactivity of the antibodies with their respective tumour cells. When given to mice preinoculated with tumour cells 2, 24, 72, and 120 hours before the beginning of treatment the chlorambucil-bound antibody was a much more effective tumour inhibitor than chlorambucil or the antibody alone. In a patient with disseminated malignant melanoma injection of the chlorambucil-bound anti-melanoma antibody first locally into a few metastatic nodules and then by the intravenous route was followed by the regression of all the metastatic nodules.

Aged