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Biomedical subjects

S D Gray

Publications and source records attributed to S D Gray.

At least 91 records · Page 5Linked to original sources
PubMed1981

Reactivity of helical strips of carotid arteries from cold- and warm-acclimated rabbits: effects of adrenergic agents, angiotensin II, and KCI.

Increased quantities of catecholamines are found in the adrenals of animals exposed to cold and thus, many studies have focused on determining the effects of catecholamines on metabolism (calorigenesis) and thermoregulation (vasomotor control of superficial blood vessels) during severe cld stress. Many of those studies have shown that the vasoconstriction which occurs in rabbit ears subsequent to an infusion of norepinephrine is diminished in cold-acclimated animals. The present in vitro study investigates the effects of 3 adrenergic agents (phenylephrine, norepinephrine, epinephrine) and 2 non-adrenergic agents (angiotensin II and KC1) on vascular smooth muscle which is though not to participate in the thermoregulatory processes. The sensitivity of helical strips of carotid arteries from cold-acclimated (CA) rabbits to phenylephrine, norepinephrine and angiotensin was decreased from control level (WA), as was the maximum developed tension. Epinephrine showed no statistically relevant decrease in sensitivity, and KC1, showed changes in neither sensitivity nor maximal tension. Histological examination of cross-sections of carotid arteries did not reveal any decrease in wall thickness which might account for the decrease in sensitivity and maximal tension. It is suggested that arterial smooth muscle throughout the body is affected by prolonged cold exposure in its responses to a wide range of constrictor agents.

Acclimatization↗
PubMed1979

Effect of vasopressin on vascular smooth muscle from cold- and warm-acclimated rabbits.

Contractile properties of helical auricular arterial strips from warm- and cold-acclimated (WA and CA) rabbits were studied to determine whether vascular smooth muscle shows a cold-induced alteration in response to vasopressen (Vp), similar to the effect seen with catecholamines. The CA response was decreased at all Vp concentrations tested and the decreases were significant at doses between 0.4--100.0 mUnits Vp/ml. Results are discussed in relation to the altered renal tubular response to Vp which has previously been reported to occur in cold-acclimated animals.

Acclimatization↗
PubMed1977

Reactivity of neonatal canine aortic strips.

To determine whether vascular reactivity in the young animal is significantly different from that of the mature animal, helical strips of thoracic aorta were suspended in an organ bath of Krebs bicarbonate solution, and isometric tension was measured. The effects of norepinephrine, phenylphrine, tyramine, and KCl were studied. The neonatal vascular strips were less sensitive than adult strips to the adrenergic agents, but responsiveness to KCl was comparable in both groups.

Age Factors↗
PubMed1976

Effect of angiotensin II on neonatal lamb carotid arteries.

Isometric tension was measured in arterial strips from neonatal lambs and adult sheep, after stimulation by angiotensin II. During the early maturation period immediately following birth (3 weeks) there was a progressive increase in sensitivity to the agent.

Age Factors↗
PubMedDate not supplied

Neonatal vocal cord paralysis.

The consultants agree that surgery is a common cause of unilateral vocal cord paralysis in neonates. In the absence of a history of surgery, they would evaluate a neonate for cardiovascular or central nervous system anomalies. None believes a relationship between laryngomalacia and vocal cord paralysis exists. But there is disagreement regarding the additional steps required to evaluate this child. The recommendations include endoscopy under general anesthesia with assessment of cricoarytenoid mobility, evaluation for other congenital anomalies, and observation of laryngeal dynamics (Dr. Benjamin), neurologic examination (Dr. Bailey), and no further testing (Dr. Gray). Laryngeal EMG in an infant is not an established technique and none of the consultants routinely performs this test. However, EMGs are part of the research protocol for one physician (Dr. Gray). The consensus is that aspiration is unlikely to be a problem in this case. However, if aspiration does occur, all would recommend conservative treatment. Feedings should be thickened and anti-reflux precautions taken. None was convinced that severe aspiration would be a problem. However, given the need for more aggressive treatment, the considerations would include collagen or Teflon injections or a tracheotomy (Dr. Gray) or a Nissen fundoplication, nasogastric tube feedings, or a gastrostomy (Dr. Bailey). Only one consultant would defer further treatment (Dr. Benjamin). The prognosis is generally good. Two consultants (Drs. Benjamin and Bailey) would follow a child with vocal cord paralysis by periodically repeating a laryngoscopic examination. A reinnervation procedure would be considered by one consultant at the age of 3 if the voice remains weak (Dr. Gray).

Diagnosis, Differential↗