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Biomedical subjects

L M Dolan

Publications and source records attributed to L M Dolan.

30 records · Page 2Linked to original sources
PubMed1988

Determinants of plasma atrial natriuretic factor concentrations in congenital heart disease.

Seventeen children with congenital heart disease undergoing elective cardiac catheterization were studied to define potential hemodynamic and echocardiographic determinants of plasma atrial natriuretic factor (ANF) concentrations. ANF concentrations in the right ventricle and femoral vein were measured by radioimmunoassay. Right ventricular levels were significantly higher than femoral venous levels (p less than 0.01), but the correlation between the 2 was high (r = 0.87, p less than 0.001). Stepwise multiple linear regression analysis demonstrated that right ventricular ANF concentrations were predicted by a combination of indexed right atrial area measured by 2-dimensional echocardiography, right atrial pressure, pulmonary resistance and heart rate (multiple r2 = 0.83). Femoral venous ANF concentrations were predicted by indexed right atrial area and systolic pulmonary artery pressure (multiple r2= 0.79). It was concluded that there are significant independent predictors of right ventricular and femoral venous plasma ANF concentrations in children with congenital heart disease. The right atrial area indexed by body surface area was the only significant predictor of both central and peripheral plasma ANF concentrations in the multivariate analysis.

Atrial Natriuretic Factor↗
PubMed1988

Atrial antinatriuretic factor in the developing Dahl hypertensive rat.

In order to determine the developmental pattern of atrial concentrations of atrial natriuretic factor (ANF) in the Dahl hypertension-prone rat, atrial ANF concentrations were measured in inbred hypertension-prone (S/JR) and hypertension-resistant (R/JR) Dahl rats at 5, 15, 25, and 51 days of age. In both strains, atrial ANF concentrations peaked at 15 days of age. Atrial ANF concentrations did not differ between the two strains from 5 to 25 days of age. However, by 51 days of age, atrial ANF concentrations in the S/JR rat were significantly greater than those of the R/JR rat. Combining these data with developmental patterns of plasma renin activity in S/JR rats suggests the possibility that the S/JR rat may become intravascularly volume-expanded between 25 and 51 days of age. This volume expansion may contribute to the etiology of hypertension in this model of essential hypertension.

Animals↗
PubMed1987

Short-term, high-dose, systemic steroids in children with asthma: the effect on the hypothalamic-pituitary-adrenal axis.

Children with chronic asthma frequently receive "bursts" (less than 7 days) of short-term, high-dose prednisone (1 to 2 mg/kg/day) for acute exacerbations of their disease. Certain of these patients may also require inhaled corticosteroids (IC) for control. The effect of these "bursts" on the hypothalamic-pituitary-adrenal axis (HPAA) is unclear. To test the integrity of the HPAA in such patients, we measured plasma cortisol (F) in response to serial administration of insulin-induced hypoglycemia (nadir = 34 +/- 1.2 mg/dl; mean +/- SE), followed by 250 micrograms/1.73 m2 of synthetic ACTH in the following children with asthma: group I, seven patients who received no more than one "burst" per year (0.71 +/- 0.2); group II, six individuals who received more than one "burst" per year (3.6 +/- 0.2) and no IC; and group III, 10 subjects who received more than one "burst" per year (4.7 +/- 0.3) plus IC. All patients received daily theophylline and beta-agonists; seven patients were taking sodium cromolyn. No patients received troleandomycin. Compared to group I (control subjects), 16% of group II had a subnormal response of F to hypoglycemia. In addition, a subnormal response of F to hypoglycemia or ACTH was documented in 20% and 10% of group III, respectively. All individuals with a subnormal response of F to either hypoglycemia or ACTH received four or more "bursts" per year. We conclude that as a group, children affected by asthma treated with "bursts" alone or "bursts" plus IC appear to have a normal HPAA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Atrial natriuretic polypeptide in the fetal rat: ontogeny and characterization.

The presence of immunoreactive atrial natriuretic polypeptide (ANP) has been demonstrated in fetal atria early in gestation but further definition of fetal ANP has not been reported. To characterize the principal molecular forms of fetal ANP and to compare fetal ANP to that of the adult of the same species, we extracted the atria of pregnant adult and 20-day fetal rats, the hearts of 14-day fetuses, and intact 12-day fetuses in 1 M acetic acid. Tissue collected from littermates was pooled. We measured ANP by radioimmunoassay before and after gel filtration on Sephadex G-75 in each group. ANP concentrations (means +/- 1 SD) in ng/mg protein and ng/animal were 1296 +/- 505 and 7707 +/- 1877 in adult atria (n = 17), 174 +/- 44 and 62 +/- 13 in 20-day fetal atria (n = 7), and 33 +/- 5.3 and 3.7 +/- 0.9 in 14-day fetal hearts (n = 6), respectively. Acid extracts from intact 12-day fetuses did not dilute in parallel to the standard curve; therefore, concentrations of ANP for the 12-day fetuses are not reported. ANP concentration rose from the 20-day fetus to the adult (p less than 0.0001). The major species of ANP eluting from the Sephadex column had an apparent molecular weight of 16 K in all groups. We conclude: 1) ANP is present in the fetus shortly after the completion of organogenesis; 2) 16 K ANP is the principal intracardiac species in the fetus and the adult; and 3) the existence of ANP soon after cardiac development suggests a possible role for ANP in fetal blood pressure and sodium and water homeostasis.

Animals↗
PubMed1984

Idiopathic hyperaldosteronism. A possible role for aldosterone-stimulating factor.

To test the hypothesis that idiopathic hyperaldosteronism is secondary to increased adrenal stimulation by aldosterone-stimulating factor, we measured the latter in seven patients with idiopathic hyperaldosteronism and in four patients who had undergone surgical removal of an aldosterone-producing adenoma. In the patients with hyperaldosteronism, plasma aldosterone concentrations (mean +/- 1 S.E.) were 38 +/- 10 and 78 +/- 19 ng per deciliter in the supine and upright position, respectively (P less than 0.01). Supine plasma aldosterone-stimulating factor was 81 +/- 5 ng per deciliter in 15 normal subjects and 185 +/- 10 (P less than 0.01) in the patients with idiopathic hyperaldosteronism. After removal of an aldosterone-producing adenoma, plasma aldosterone-stimulating factor was normal. The supine value in each patient with idiopathic hyperaldosteronism was above the normal range (61 to 91 ng per deciliter) and increased to 290 +/- 59 ng per deciliter after four hours of upright posture. Twenty-four hour urinary excretion of aldosterone-stimulating factor was 424 +/- 35 ng (normal, 145 +/- 3; P less than 0.01) by affinity chromatography and high-pressure liquid chromatography, and it was not suppressed after two days of treatment with dexamethasone (0.5 mg orally every six hours). At the end of 48 hours, plasma concentrations were 248 +/- 40 ng per deciliter. Plasma cortisol and ACTH concentrations were under 2 micrograms per deciliter and under 40 pg per milliliter, respectively. We conclude that increased secretion of aldosterone-stimulating factor may be the cause of idiopathic hyperaldosteronism.

Adenoma↗
PubMedDate not supplied

Hamartoma of the tuber cinereum: a comparison of MR and CT findings in four cases.

Hamartoma of the tuber cinereum is a well-recognized cause of central precocious puberty. We report three patients with an isodense, nonenhancing mass within the interpeduncular cistern identified by CT. In a fourth patient, the CT scan was normal. MR imaging was obtained in all cases and demonstrated a sessile or pedunculated mass of the posterior hypothalamus arising from the region of the tuber cinereum. The smallest mass was 2 mm in diameter and was found in the patient in whom the CT scan was normal. The signal intensity of the masses was generally homogeneous and isointense relative to gray matter on T1- and intermediate-weighted images, and hyper-intense on T2-weighted images. MR imaging accurately diagnoses hypothalamic hamartomas, identifies small hamartomas of the tuber cinereum more sensitively than CT does, and provides optimal imaging for serial evaluation while the patient is being treated medically.

Child↗