Search PubMed⌕ Search

Biomedical subjects

D G Johnson

Publications and source records attributed to D G Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1979

Reduction of plasma triglyceride concentration by acute stress in man.

Three different forms of stress all resulted in acute reduction of plasma triglyceride concentrations. Pyrogen reactions in two hypertriglyceridemic men resulted in the lowering of very-low-density lipoprotein (VLDL) triglyceride levels by 93% and 73% due to decreased secretion of this lipoprotein into plasma. More modest reductions in plasma triglycerides were observed after 2-deoxyglucose-induced intracellular glucopenia and insulin-induced hypoglycemia. With hypoglycemia, the lowering of plasma triglyceride concentration correlated significantly with the stimulation of urinary epinephrine output (r = 0.86) but with neither the urinary norepinephrine response nor with the increase in plasma immunoreactive glucagon levels. To further test whether these changes in plasma triglyceride levels were mediated via the sympathetic nervous system, hypoglycemia was evoked by insulin in subjects with traumatic spinal cord transactions. Two such subjects, who demonstrated sympathetic stimulation in response to hypoglycemia, had evidence of reduced VLDL secretion into plasma, while in two who had no evidence of an adrenergic response. VLDL secretion was not inhibited. Thus, acute lowering of plasma triglyceride concentrations by certain forms of stress appears to be mediated via the sympathetic nervous system.

Acute Disease↗
PubMed1979

The lower esophageal sphincter in gastroesophageal reflux in children.

Esophageal function was evaluated in 51 children less than 2 years of age with radiologic evidence of gastroesophageal reflux. Detection of an acid esophageal pH was a sensitive measure of gastroesophageal reflux. Lower esophageal sphincter pressures were greater in reflux patients with respiratory symptoms (18.0 +/- 1.4 mm Hg) than in reflux patients without respiratory symptoms (9.5 +/- 1.0 mm Hg). The intra-abdominal segment of the lower esophageal sphincter was shorter in patients with reflux than in controls (0.51 +/- 0.05 cm vs. 0.75 +/- 0.08 cm). It was also shorter in patients requiring surgical therapy (0.34 +/- 0.05 cm) than in those responding to medical therapy (0.63 +/- 0.07 cm).

Age Factors↗
PubMed1979

Catecholamine elevation in iron deficiency.

Iron-deficient rats have increased blood and urinary catecholamines regardless of whether anemia is or is not present. The catecholamine response in both iron-deficient and control animals is largely temperature dependent, showing little difference at the isothermic temperature of 30 degrees C but a two- to threefold increase in iron-deficient animals over controls at lower temperatures. The iron-deficient rat is unable to maintain body temperature at 4 degrees C and this is independent of anemia or of food intake. When animals are run on the treadmill for 4 h, body temperatures increase but the difference observed at 4 degrees C between iron-deficient and control animals persists. The underlying abnormality in temperature regulation and in catecholamine response disappeared after 6 days of iron therapy.

Animals↗
PubMed1979

Parathyroid hormone release is not associated with acute sympathetic arousal in goats.

Physiological activation of the sympathetic adrenomedullary (SAM) axis following both thermal and non thermal stress was assessed by changes in serum norepinephrine, glucose and/or protein as well as indices of peripheral blood flow. The occurrence of elevated serum parathyroid hormone (PTH) did not reliably reflect SAM activation as might be predicted from pharmacological studies that document a beta adrenergic receptor mechanism in the parathyroid gland that mediates catecholamine stimulated release of PTH into the circulation. The beta agonist isoproterenol at 1 microgram/min for 60 min did produce a transient increase in serum PTH at 20 min. Overall, the data raise doubts about the physiological significance of the adrenergic receptor in the parathyroid gland. Significant increases in serum PTH of 67% and 109% above basal respectively were seen following ruminal loading with cold and thermoneutral water. Associated with the PTH change were increased serum phosphorus and elevated or constant serum protein and serum total calcium.

Animals↗
PubMed1978

Infant tracheostomy. A new look with a solution to the difficult cannulation problem.

Although most infant airway and ventilatory problems will be best solved by the use of endotracheal tubes, clear-cut indications for tracheostomy exist. Past reticence to use tracheostomy for infants has been due mainly to the fear of decannulation problems. Recognition of obstructive airway lesions, particularly the lumen-narrowing tracheal stomal granuloma, has been facilitated by the routine use of the newer infant bronchoscopes with optical telescopes. Successful decannulation begins with proper tracheostomy technique, and continues through tracheostomy management and a well-conceived decannulation program. Decannulation should include evaluation of the structure and function of the airway endoscopically and it may include translaryngeal endoscopic resection or formal surgical removal of any obstructing lesions. Experienced nursing personnel are essential to the entire program.

Airway Obstruction↗
PubMed1978

Survey of graduates of a traditionally black college of medicine.

Over 700 Howard University medical alumni of seven representative classes graduating from 1955 to 1975 were surveyed by questionnaire in 1975-76. Replies of the 311 respondents confirm that this college of medicine has trained a substantial number of physicians who are providing care to blacks, the economically disadvantaged, and residents of inner city areas. Survey findings may also be useful in reaffirming the necessity for training more minority physicians, assessing the impact which the increasing number of minority physicians will have on health care delivery in this country, and suggesting the probable practice patterns of future minority graduates of U.S. medical schools.

Adult↗
PubMed1978

Epinephrine and dopamine beta-hydroxylase secretion from bovine adrenal.

The perfusate of the isolated, acetylcholine-stimulated bovine adrenal was studied for epinephrine (E) concentration and dopamine beta-hydroxylase (DBH) activity. Analysis of single stimuli showed that DBH disappeared from the perfusate with a t1/2 of 19.1-29.0 min. whereas E disappeared with a t1/2 of 0.78-1.0 min. Stimulation every 5 min over 105 min caused a gradual decline in E concentration to 36% of its initial value, whereas DBH activity reached a plateau after the second stimulus and thereafter remained unchanged. The decline in E was not influenced by addition of catecholamine precursors and biosynthetic cofactors to the medium and was not accompanied by a shift in the ratios of E and norepinephrine (NE) in the perfusate. Inhibitors of DBH activity were not detected in the perfusate and nonexocytotic leakage of DBH into the perfusate did not occur. These results document the temporal dissociation of the appearance and disappearance of DBH and E after a single stimulus and the progressive dissociation of DBH and E secretion under conditions of prolonged perfusion with rapid and repetitive stimulation. Possible explanations of these observations are offered.

Acetylcholine↗
PubMed1978

Study of U.S. medical school applicants, 1976--77.

This annual study contains descriptive statistics on applicants to the 1976--77 freshman classes of U.S. medical schools. In contrast to the growth rates of the early 1970s, the total number of applicants declined slightly for the second successive year. However, comparisons with past applicant pools show a continued increase in the annual number of women applying and a modest increment over the previous year in applicants from minority groups. For the first time in the annual series the 1976--77 study includes data on applicants' size of hometown and summarizes information collected on marital status, country of citizenship, and undergraduate degree level.

Adult↗
PubMed1977

Childhood gastroesophageal reflux. Neurologic and psychiatric syndromes mimicked.

Thirteen infants and children with proved gastroesophageal (GE) reflux had complaints that suggested a CNS disorder. Symptoms began in early infancy in ten cases, but accurate diagnosis and proper treatment were not instituted in three cases until three to five years of age. A CNS basis for their disease was suspected because they exhibited specific signs or because the importance of associated gastrointestinal (GL) and respiratory tract symptoms was not appreciated. The presenting CNS symptoms and signs included dystonia in 11, developmental retardation in ten, dysphagia in nine, seizures in six, and extreme irritability in ten. We believe that the diagnosis of symptom-causing GE reflux is being missed regularly. The effects of proper medical or surgical therapy are often dramatic, and the consequences of missed diagnosis or improper treatment are potentially lethal.

Age Factors↗
PubMed1977

Hyperinsulinism of hepatic cirrhosis: Diminished degradation or hypersecretion?

The breakdown of proinsulin in the pancreatic beta cell yields insulin and C-peptide which are secreted in equimolar amounts. Unlike insulin, C-peptide is not degraded significantly by the liver, so that its measurement should give a better assessment of insulin secretion than estimation of peripheral insulin levels alone; particularly in the presence of hepatic dysfunction. Plasma C-peptide and insulin response to an oral glucose load have therefore been assessed in 14 cirrhotic and 7 normal subjects. Cirrhotic patients were divided into hyperinsulinaemic and normoinsulinaemic groups based on fasting plasma-insulin concentrations. Fasting blood-blucose and plasma-C-peptide concentrations were the same in normal and cirrhotic subjects, suggesting that basal pancreatic insulin secretion was the same in all subjects. Thus the C-peptide/insulin ratio was significantly decreased in hyperinsulinaemic subjects (2-13 +/- 0-31, compared with 4-63 +/- 0-48 in controls). After oral glucose, the two groups of cirrhotic patients showed the same glucose intolerance. C-peptide concentrations were also the same but insulin concentrations were markedly increased in the hyperinsulinaemic group. It is suggested that pancreatic insulin secretion is not increased in cirrhosis and that the peripheral hyperinsulinism is due solely to decreased hepatic insulin degradation secondary to either spontaneous portal-systemic shunting or to parenchymal damage.

Administration, Oral↗