Biomedical subjects

R Frayser

Publications and source records attributed to R Frayser.

At least 19 recordsLinked to original sources

PubMed1987

Inspiratory neuron activity in the ventrolateral medulla of the dog.

The purpose of this study was to describe the distribution and activity pattern of respiratory neurons located in the ventrolateral medulla (VLM) of the dog. Spike activity of 129 respiratory neurons was recorded in 23 ketamine-anesthetized spontaneously breathing dogs. Pontamine blue dye was used to mark the location of each neuron. Most VLM neurons displaying respiratory related spike patterns were located in a column related closely to ambigual and retroambigual nuclei. Both inspiratory and expiratory neurons were present with inspiratory units being grouped more rostrally. The predominant inspiratory neuron firing pattern was "late" inspiratory, although eight "early" types were located. All expiratory firing patterns were the late expiratory variety. Each neuron burst pattern was characterized by determining burst duration (BD), spikes per burst (S/B), peak frequency (PF), time to peak frequency (TPF), rate of rise to peak frequency (PF/TPF), and mean frequency. CO2-induced minute ventilation increases were associated with decreases in BD and TPF and increases in PF, S/B, and PF/TPF. In 11 experiments the relative influences of vagotomy and tracheal occlusion on late inspiratory units were compared. Tracheal occlusion increased late inspiratory BD and S/B but did not alter PF/TPF. Vagotomy increased BD and S/B beyond those obtained by tracheal occlusion and, in some neurons, decreased the PF/TPF. We conclude that the location of respiratory units in the VLM of the dog is similar to that in other species, the discharge pattern of VLM respiratory units is similar to those in cat VLM, and vagotomy and tracheal occlusion affect discharge patterns differently.

Action Potentials↗

PubMed1978

Branched chain amino acid metabolism in the retina of diabetic rats.

Diabetes is known to produce increased levels of the branched chain amino acids in plasma, heart and muscle as well as increased oxidation of [14C]-leucine by nerves and muscles from rats. Plasma and retinas from streptozotocin diabetic rats had significant elevations in branched chain amino acid levels compared to control. Retinas from diabetic rats have been found to oxidize significantly more of the branched chain amino acids, leucine, isoleucine and valine than did control retinas when incubated in media containing 16.5 mmol/l glucose. Neither the extracellular space nor the tissue pool of leucine was significantly different in the two groups. The addition of 19 amino acids, at normal plasma concentrations, to the incubation media resulted in 80 percent suppression of leucine oxidation without significant change in incorporation of [14C] into protein. These results suggest that the major role for the branched chain amino acids in the rat retina is in protein synthesis which is not affected by short-term diabetes.

Amino Acids↗

PubMed1977

Immunocytochemical localization of lysozymes in respiratory and other tissues.

Immunostaining paraffin sections of appropriately fixed tissues with an antiserum to human urinary lysozyme as the primary step in an immunoglobulin-peroxidase bridge method has localized lysozyme in previously recognized sites such as Paneth cells, renal tubules, and lymph node macrophages in several species. In addition, lysozyme was demonstrated in the ciliary layer of the trachea, and type II pneumocytes, as well as cells of presumed mucoid nature in laryngotracheal glands. Large stellate cells in follicle centers in the lymph nodes and spleen and in the medulla of the thymus evidenced strong lysozyme reactivity. Granular pneumocytes disclosed immunoreactivity for lysozyme also at the ultrastructural level. Lysoplate assay demonstrated lysozyme in abundance in both the cellular pellet and acellular supernatant of rat alveolar wash fluid and in rat lung after repeated washing of alveoli. Hamster lung differed from the others in failing to immunostain for lysozyme and affording no evidence for content of lysozyme as determined by lysoplate assay. Sites stained with antiserum to human urinary lysozyme failed to stain with antiserum to egg white lysozyme. However, the pyloric glands, Golgi elements in intestinal epithelium, the surface of the colon, and the proximal straight renal tubule of the mouse stained exclusively with the antiserum to hen egg white lysozyme. Many sites staining with antiserum to urinary lysozyme in respiratory, renal, and lymphoid tissue lacked reactivity in control sections exposed to this antiserum after it was absorbed with purified urinary lysozyme. However, mucous acini in submandibular glands, although failing to stain with other control procedures, retained towared the absorbed antiserum, possibly through reacting with an antibody other than that for human urinary lysozyme. A number of cell types containing proteinaceous cytoplasmic granules stained in control sections exposed to normal serum in place of antilysozyme serum in the immunoglobulin-peroxidase bridge procedure and, thus, possessed selective, but nonimmunospecific affinity for immunoglobulin. Cell types that stained with antiserum to hen egg white lysozyme lost affinity for the antiserum after its absorption with egg white lysozyme but retained the affinity after absorption with urinary lysozyme.

Animals↗

PubMed1975

Hormonal and electrolyte response to exposure to 17,500 ft.

Hormone, electrolyte, and body fluid compartment changes were studied in subjects who either spent time at 10,000 ft before flying to 17,500 ft or were premedicated with acetazolamide and flown directly to 17,500 ft. In the former group, at 10,000 ft, renin and aldosterone were not different from control. Cortisol increased significantly from 9.8 to 19.5 mug/100 ml on the third day. At 17,500 ft, renin, aldosterone and cortisol were significantly elevated on day 3 but had returned to control levels by day 5. Sodium and potassium excretion was significantly reduced at both altitudes. Total body water, extracellular and plasma volume were reduced (P less than 0.05) at 17,500 ft. Subjects pretreated with acetazolamide and flown directly to 17,500 ft had significant increases (P less than 0.001) in plasma renin, aldosterone, and cortisol levels during the first 4 days at altitude. On day 1 there was a decrease of 45% in sodium and 38% in potassium excretion. On day 4 there was a decrease of 63% and 51%, respectively. These changes are not associated with the premedication. The initial changes may reflect the immediate response to stress and alkalosis followed by a return to control levels as the body adapts to altitude.

Acetazolamide↗

PubMed1974