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Biomedical subjects

J Richardson

Publications and source records attributed to J Richardson.

At least 325 records · Page 18Linked to original sources
PubMed1977

Intrarenal distribution of plasma flow in cirrhosis as measured by transit renography: relationship with plasma renin activity, and sodium and water excretion.

1. The intrarenal distribution of plasma flow was determined with a technique based on the analysis of the transit time of sodium o-[131I]- iodohippurate through the kidney in 43 patients with cirrhosis with near-normal total renal perfusion. 2. Twenty-five of the patients had an abnormal pattern of transit times, suggesting a redistribution of plasma flow from outer cortical to juxtamedullary nephrons. 3. Plasma renin activity ranged from below normal to six times normal and high values were found only in patients showing an abnormal pattern of transit times. The latter was also found to be related to sodium retention and a reduced renal capacity to excrete free water.

Adult↗
PubMed1976

Nonadrenergic inhibitory nervous system in human airways.

Human airways, from the middle of the trachea to the distal bronchi, were studied in vitro for the presence of inhibitory nerves. The tissue was obtained from operations and from recent autopsies. Electrical field stimulation of the tissues demonstrated cholinergic, excitatory nerves and their effect was blocked by atropine. Field stimulation of the tissues, in the presence of atropine, relaxed the smooth muscle even when the muscle was contracted by histamine. The field stimulation-induced relaxation was neither blocked nor modified by adrenergic blocking agents. Maximum relaxation of the bronchial muscle was obtained with a pulse duration of 1-2 ms, 70 V, and frequencies of 20 Hz and greater. The tracheal smooth muscle showed 85% of maximal relaxation with a frequency of 10 Hz. Tetrodotoxin, blocked the field stimulation-induced relaxation for pulse durations of 2 ms; this indicated that nerves were being stimulated. The airway system shows some of the characteristics of the nonadrenergic inhibitory system in the gastrointestinal tract and of the system reported in the guinea pig trachealis muscle. No evidence of adrenergic inhibitory fibers was found in the bronchial muscle with either pharmacological or histochemical techniques. These findings suggest that the nonadrenergic inhibitory system is the principal inhibitory system for the smooth muscle of human airways. We suggest that a defect in the airway system, such as that shown in the gastrointestinal tract, may be an explanation for the hyperreactive airways of asthma and chronic bronchitis.

Animals↗
PubMed1976

Uptake and transport of exogenous proteins by respiratory epithelium.

The tracer proteins, horseradish peroxidase and ferritin, placed in the trachea of guinea pigs were taken up by epithelial cells and transported to the extracellular space. The interval between the introduction of the tracer proteins into the lumen of the trachea and the morphologic demonstration of the porteins in the extracellular space or within the basal portion of the cells was between 30 and 60 minutes. The proteins were transported in vesicles and no penetration of the epithelial intercellular tight junctions was found. The intercellular tight junctions were made permeable to horseradish peroxidase by anesthetic ether and this permeable epithelium was compared to the vesicle type transport. Transepithelial transport of proteins is a possible mechanism for the introduction of antigenic material into the subepithelial lymphoid tissue and this transport may also be of importance in the late onset type of asthma.

Animals↗
PubMed1975

Pharmacologic studies of Hirschsprung's disease on a murine model.

In studies of the pharmacology of a murine model of aganglionosis, the contracted aganglionic portion of the terminal bowel showed slow regular contractions of high amplitude in comparison to the rapid low-amplitude contractions of a normal segment of bowel. An absence of the nonadrenergic inhibitory system was demonstrated in the aganglionic, contracted portion of the bowel. This lack of the nonadrenergic system confirms previous findings in human tissue. It is proposed that absence of this inhibitory system in the aganglionic portion of the bowel results in the principal pathophysiologic findings in Hirschsprung's disease.

Acetylcholine↗
PubMed1975

Crystal structure of bovine Cu,Zn superoxide dismutase at 3 A resolution: chain tracing and metal ligands.

An electron density map at 3 angstrom resolution has been calculated for Cu2+, Zn2+ superoxide dismutase from bovine erythrocytes, and the course of the main chain has been traced. The dominant structural feature is an 8-stranded barrel of antiparallel beta-pleated sheet. There is one very short helical section and two long loops of non-repetitive structure. The Cu and Zn are bound between the loops and one side of the beta barrel and are about 6 Angstrom apart, with a common histidine ligand. The Cu has four histidine ligands in a somewhat distorted square plane, and the Zn has three histidines and an aspartate in approximately tetrahedral arrangement. The two coppers of a dimer are about 34 Angstrom apart. The two subunits have essentially the same conformation and have an extensive contact area that mainly involves hydrophobic side chain interactions. The overall folding pattern of the polypeptide chain is very similar to that of an immunoglobulin domain.

Animals↗
PubMed1975

A simple freezing and storage method to preserve the stimulating function of leukocytes in the mixed leukocyte reaction.

Human peripheral blood leukocytes retain their capacity to function as stimulating cells in the one way MLR after freezing and storage at - 70 degrees C by a simple and inexpensive method. This storage method facilitates the use of a standard stimulating pool of cells from three donors which may provide a quantitative assay for testing the ability of cells to respond to allogeneic cells in culture.

Freezing↗