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Biomedical subjects

D Baum

Publications and source records attributed to D Baum.

At least 55 records · Page 3Linked to original sources
PubMed1979

Glucose-induced insulin release during acute and chronic hypoxia.

Glucose-induced insulin release was studied in young dogs during acute and chronic hypoxia, alone and in combination. Six experimental animals were rendered chronically hypoxic (PaO2, 43.4 +/- 0.5 torr) by creation of a right-to-left shunt at age 6-8 wk. Six control animals underwent sham procedures (PaO2, 85 +/- 2.2 torr) at the same age. During air breathing, glucose-induced plasma insulin increases were similar in chronically hypoxic and control animals. When severe hypoxia was acutely produced by ventilation with low-oxygen mixtures in experimental (PaO2, 23.7 +/- 1.7 torr) and control animals (PaO2, 26.3 +/- 1.0 torr), plasma insulin responses were markedly inhibited in both. On the other hand, acutely lowering oxygen tensions of control animals (PaO2, 37.5 +/- 1.4 torr) to levels close to those of air-breathing chronically hypoxic animals did not affect the insulin responses. These observations suggest that glucose-induced insulin release is inhibited by acute severe hypoxia despite previous chronic oxygen deficiency. In contrast, moderate hypoxia, acute or chronic, does not appear to affect the insulin response to a glucose load.

Animals↗
PubMed1979

Hyperglucagonemia and alpha-adrenergic receptor in acute hypoxia.

The plasma immunoreactive glucagon (IRG) response to hypoxia was studied in puppies. Three groups of paired experiments were performed. In group I, 8% O2:92% N2 ventilation (PaO2 20--30 torr) produced a rise in plasma IRG and glucose as well as hypotension and bradycardia. However, when group I was air ventilated (PaO2 greater than 70 torr) and given glucose infusions producing hyperglycemia of similar degree, plasma IRG was unchanged. Group II received alpha-adrenergic blockade (phenoxybenzamine). When made hypoxic, group II developed no significant IRG rise and less hyperglycemia than with hypoxia alone. Hypotension was more severe with hypoxia plus alpha-blockade. Phenoxybenzamine itself did not change plasma IRG or glucose during air breathing. Group III receivi developed hyperglucagonemia and hyperglycemia not significantly different from that with hypoxia alone. However, hypoxia-caused hypotension and bradycardia was more pronounced with beta-blockade. No change in plasma IRG or glucose occurred in group III animals breathing air. These data suggest that a) glucagon release is caused by acute oxygen deficiency, and b) the hypoxic response is largely adrenergically mediated with the major role played by the alpha-receptor.

Animals↗
PubMed1979

An important complication of Hancock mitral valve replacement in children.

Nine children ages 2--15 years have undergone mitral valve replacement (MVR) with Hancock porcine heterograft valves for severe mitral insufficiency. The etiology of the mitral valve disease was rheumatic in two patients, and congenital in seven. Porcine valve sizes ranged from 19--31 mm. Follow-up has been from 1.6 to 6.1 years (mean, 4.3 years). All nine children have had marked postoperative improvement, no thromboembolic complications despite no long-term anticoagulations, and no episodes of endocarditis. There have been no early or late deaths. Although six of the nine patients remain asymptomatic, three others developed severe fibrocalcific obstruction of the heterograft, requiring valve re-replacement at 3.5, 3.6, and 4.8 years following the initial valve replacement. This complication has not been previously reported in children. It is a factor that must be considered when deciding on MVR for children and their postoperative management.

Adolescent↗
PubMed1977

Adipose hypocellularity in cyanotic congenital heart disease.

Height, weight, total body fat, adipocyte size (cellular lipid content), total adipocyte number, and lean body mass were studied in two groups of similar aged children with congenital heart disease. One group was comprised of 19 children cyanotic from infancy. The second group was made up of 16 asymptomatic, acyanotic patients and served as the basis for age and sex adjusted comparisons. Cyanotic patients were lighter (P less than 0.001) and had less total body fat (P less than 0.001). Although there was no difference in adipocyte size, total adipocyte number was less in the cyanotic children (P less than 0.001), suggesting that the reduced body fat found with cyanosis is due to adipocyte hypocellularity. The additional observation that cyanotic patients were shorter (P less than 0.003) and had less lean body mass (P less than 0.001) than noncyanotic children implies that early hypoxemia produces widespread abnormalities which impair growth.

Adipose Tissue↗
PubMed1976

Beta adrenergic receptor dysfunction in hypoxic inhibition of insulin release.

Insulin secretory responses were measured in air-breathing puppies given epinephrine, and compared with insulin responses during acute hypoxia. In puppies with oxygen deficiency, insulin levels declined, whereas during epinephrine infusion, they remained stable or increased slightly. When glucose was given during phentolamine administration, insulin levels rose more in the epinephrine-treated animals than in the hypoxic animals, despite similar blood glucose levels. Theophylline-induced insulin release was increased by epinephrine, but inhibited by hypoxia. When the beta adrenergic blocking agent, propranolol, was given with the epinephrine, the insulin response to theophylline was markedly reduced and similar to that observed during hypoxia. Control studies with propranolol showed no effect of this agent on glucose-induced insulin release. Isoproterenol infusion caused elevated insulin levels during air ventilation but this response was suppressed by hypoxia. From these data, we have concluded that the difference between hypoxia and epinephrine can be explained by a reduced ability of catecholamines to stimulate the beta adrenergic receptor during hypoxia. We hypothesize that this effect leads to an unmodulated alpha adrenergic inhibition of insulin release.

Animals↗
PubMed1976

Different lipolytic effects of theophylline and dibutyryl cyclic AMP in vivo and in vitro.

Both dcAMP and theophylline are known to promote lipolysis in vitro by increasing intracellular cAMP. Although theophylline stimulates FFA mobilization in vivo as well, a report of low circulating FFA levels in the rat given dcAMP suggested that dcAMP may inhibit lipolysis in the intact animal. To explore this possibility, a comparison of the in vitro and in vivo lipolytic effects of theophylline and dcAMP was made in the young dog. Circulating glycerol and FFA levels rose following the administration of theophylline. While glycerol and FFA fell slightly in puppies given dcAMP, only the FFA change was significant. Epinephrine infusions given alone produced sustained elevations of glycerol and FFA. When theophylline was given in conjunction with ongoing epinephrine infusions, plasma glycerol and FFA levels remained high. On the other hand, epinephrine-stimulated lipolysis was markedly inhibited by dcAMP, as shown by pronounced falls of glycerol and FFA from the elevated levels found with epinephrine alone. In vitro studies involving fragments of puppy adipose tissue reveal that epinephrine, theophylline, and dcAMP promoted glycerol release. In contrast to the in vivo observations, lipolysis was also stimulated by combinations of both epinephrine and theophylline as well as by epinephrine and dcAMP. Thus, theophylline stimulates lipolysis in vitro and in vivo in the puppy. In contrast, dcAMP stimulates lipolysis in vitro but inhibits this action in the intact animal. This important difference in the two pharmacologic agents suggests the need for caution when using them in in vivo studies involving the action of cAMP.

Adipose Tissue↗
PubMed1975

Echocardiographic findings in Uhl's anomaly. Demonstration of diastolic pulmonary valve opening.

The echocardiographic findings in a case of Uhl's anomaly, or congenital hypoplasia of the right ventricular myocardium, are reported. Diastolic opening of the pulmonary valve is described. Comparison is made with echocardiograms in Ebstein's disease of the tricuspid valve, and it is suggested that echocardiography can help in differentiating these two entities. In addition to the pulmonary valve finding, increased right ventricular dimension, delayed tricuspid closure and abnormality (prolapse) of the mitral valve were noted. The echocardiographic findings are compared with cardiac catheterization data.

Adolescent↗