Biomedical subjects

D Higgins

Publications and source records attributed to D Higgins.

111 records · Page 7Linked to original sources

PubMedDate not supplied

Release of 3H-norepinephrine from adrenergic nerves in chick heart.

The metabolic disposition of 3H-norepinephrine (3H-NE) was studied in adrenergic nerves of the chick heart. Spontaneous overflow of 3H was associated with considerable metabolism of NE; about 90% of the 3H-NE appeared as acid and neutral metabolites. Overflow of 3H increased markedly during depolarization by K+ and over 70% of the 3H was unmetabolized 3H-NE. This 3H-NE seems to have been protected from intraneuronal metabolism (probably by vesicles) and to have been released by exocytosis. By contrast, tyramine-induced overflow included a large proportion of metabolites (approximately 70%) perhaps because of a nonexocytotic release mechanism similar to that in adult tissues.

Adrenergic Fibers↗

PubMedDate not supplied

Comparison of isocapnic hyperventilation and histamine or methacholine inhalation for the assessment of airway responsiveness.

Several stimuli have been used to evaluate the degree of airway hyperresponsiveness in asthma. Each of these has possible advantages and disadvantages when compared to the other methods. The most widely used involves the inhalation of chemical bronchoconstrictors, most commonly histamine or methacholine. This paper contrasts these inhalation tests with airway challenges using isocapnic hyperventilation of dry air. Isocapnic hyperventilation uses a naturally occurring stimulus to provoke bronchoconstriction rather than a chemical stimulus and can be administered in a dose-response fashion. Therefore, isocapnic hyperventilation may be particularly useful in epidemiologic surveys. The maximal dose administered, however, is determined by the level of a subject's maximal voluntary ventilation: also the equipment needed to administer the challenge is relatively complex when compared to other methods. By contrast, histamine and methacholine inhalation tests require simple, inexpensive equipment and can be inhaled at high concentrations, which means that airway responsiveness can be measured even in many nonasthmatic subjects. However, at high inhaled concentrations, histamine has many more systemic side effects than methacholine. Once the factors known to influence the measurements of airway responsiveness are controlled, the measurements made with one method correlate well with all other methods. Therefore, the method chosen will often depend on the requirements of the study or clinical laboratory.

Asthma↗

PubMedDate not supplied

Unilateral lung volume reduction in preparation for contralateral pneumonectomy.

A case of staged trans-sternal unilateral lung volume reduction (LVR) on the right followed by contralateral pneumonectomy for a locally advanced left lung malignancy is presented. The predicted symptomatic and functional benefit offered by LVR was felt to be necessary before the removal of the left lung. The patient, a 50-year-old male, with a history of chronic air flow limitation secondary to bullous emphysema, underwent a left pneumonectomy six weeks following a right LVR procedure for poor pulmonary function secondary to generalized emphysema. On admission, forced expiratory volume in 1 s (FEV1) was 1.37 L, 47% of predicted with an FEV1/forced vital capacity of 56%. Five weeks after the unilateral LVR, the patient's FEV1 was 1.85 L, and one year postdischarge from hospital, FEV1 was 0.9 L. One year after discharge, the patient did not require oxygen support, and was active and free of malignant disease.

Carcinoma, Non-Small-Cell Lung↗