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Biomedical subjects

H E Cohn

Publications and source records attributed to H E Cohn.

At least 37 records · Page 2Linked to original sources
PubMed1989

Adrenal secretion of glucocorticoids during hypoxemia in fetal sheep.

This work was undertaken to investigate the fetal adrenal corticoid secretory response to hypoxic stress in late gestation. Experiments were performed in two groups of fetal sheep of different gestational ages, group I, 129-132 (mean, 130) days and group II, 135-139 (mean, 136) days. Fetuses were prepared with chronic adrenal cannulas as well as peripheral arterial and venous catheters. With the fetus at rest and after 7, 9, 11 and, in some instances, 30 and 60 min of hypoxia (maternal FIO2 10%), precisely timed (2 min) samples of adrenal effluent were collected for determination of cortisol (F) and corticosterone (B) secretion rates. Peripheral samples were obtained intermittently for blood gas and lactate determinations. Resting corticoid secretory rates were highly variable, suggesting an episodic secretory pattern. Corticoid secretory responses to hypoxemia were significantly elevated at 7-11 min, peaked at 30 min, and remained stable at 60 min. Specifically, in group I, F secretion increased from a baseline value of 37 +/- 19 ng/min to a peak hypoxemic response of 376 +/- 80 ng/min; B secretion increased from 6 +/- 4 to 170 +/- 32 ng/min. In group II, F secretion increased from 99 +/- 20 to 653 +/- 107 ng/min; B secretion increased from 12 +/- 5 to 200 +/- 28 ng/min. When related to adrenal gland weight, there was no difference between F secretory responses in groups I and II, whereas relative B secretory responses were lower in group II than in group I at 9 and 11 min of hypoxemia. We conclude that the 129-139 day sheep fetal adrenal cortex is highly sensitive to hypoxic stress with the effect presumably mediated by elevated levels of endogenous ACTH. The B stress response decreases as gestational age advances from the 129-132 day range to 135-139 days.

Adrenal Cortex↗
PubMed1987

Plasma catecholamines in the hypoxaemic fetal rhesus monkey.

To assess the response of the sympathoadrenal system of the primate fetus to oxygen deprivation, we measured plasma catecholamines in 8 chronically catheterized fetal rhesus monkeys. A range of fetal hypoxaemia was produced by having the mother inspire 15, 10, or 9% oxygen mixtures while tranquilized with ketamine. Catecholamines from fetal carotid and maternal femoral arteries were measured by radioenzymatic assay. Fetal plasma norepinephrine and epinephrine concentrations increased significantly at all levels of hypoxaemia, but dopamine increased only at very low fetal oxygen tensions. Norepinephrine levels exceeded those of epinephrine and dopamine under all conditions. Relatively more severe hypoxaemia was necessary to elevate concentrations of epinephrine above baseline as compared with norepinephrine. A negative exponential correlation (P less than 0.001) was found between both fetal arterial PO2 and oxygen content and plasma norepinephrine and epinephrine, which was qualitatively similar to that observed previously in the sheep fetus. Maternal catecholamines were found to increase during hypoxaemia as well, but to a lesser degree than in the fetus.

Animals↗
PubMed1986

Bronchoalveolar cell carcinoma of the lung.

A multivariable analysis was performed of all patients registered and confirmed to have bronchoalveolar cell carcinoma of the lung in the Tumor Registry of Thomas Jefferson University Hospital between 1969 and 1983. These 122 patients were reviewed for age, sex, smoking history, occupational exposure, symptoms, radiographic findings, methods of diagnosis, clinical and pathologic staging, methods of treatment, survival, and complications of treatment. No correlation could be found in this series between a patient's age, sex, smoking history, or occupational exposure and the incidence or outcome of the disease. Seventy-one of the 122 patients in this series were asymptomatic, and the carcinoma was discovered in them by routine chest roentgenogram. Of these asymptomatic patients, 50 were seen with pathologic stage I disease. Of the 51 symptomatic patients, 32 (65%) were seen with stage IIIm0 or IIIm1 disease. Despite medical evaluations, 77% of the T1 and T2 lesions required thoracotomy for diagnosis. The overall five-year survival rate was 42.3%, ranging from 75% for those with stage I disease to 8.7% for those with stage IIIm1 disease.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1986

Dual tracer imaging for localization of parathyroid lesions.

During the period from July 1983 through October 1984, a group of 38 patients with elevated serum calcium, parathormone (PTH) and/or clinical suspicion of hyperparathyroidism were studied by TI-201 Tc-99m dual tracer parathyroid imaging (DTPI). Seventeen of 18 parathyroid lesions were identified correctly. There was one false-negative, and the size of the adenoma missed by DTPI was less than 1.0 cm in diameter (1.0 x 0.5 x 0.2). There was one true-negative case. The other fifteen with negative scans are being followed clinically. Because of the small population studied, statistical analysis was not ascertained. However, this simple, noninvasive procedure has become a very useful diagnostic tool for the detection and localization of parathyroid lesions causing hyperparathyroidism, and the DTPI should be used in conjunction with ultrasonography and CT scanning in the preoperative evaluation in primary and secondary hyperparathyroidism.

Adenoma↗
PubMed1985

Complications and mortality associated with cardiac catheterization in infants under one year: a prospective study.

To evaluate complications and mortality following cardiac catheterization (CC) in patients under one year of age, we prospectively examined 312 CC on 273 patients from the centers in the New England Regional Infant Cardiac Program during a one-year period. Among CC performed on patients less than four months old, the incidence of complications requiring treatment was 12%; for patients 4-12 months, it was 1.5% (p less than 0.02). By pre-CC risk assessment, 13% of CC were high risk, 21% medium risk, and 66% low risk. The incidence of major complications was much greater among the High Risk (30%) compared with Medium Risk (14%) (p less than 0.05) and with Low Risk (4%) (p less than 0.001). The overall mortality rates 24 h, 48 h, and one week after CC were 3.8%, 8.3%, and 13.5%, including patients with inoperable lesions and those having cardiac surgery, while deaths directly attributable to a CC complication were 0, 0.3%, and 0.3%, respectively. We can predict, prior to CC, the high-risk cases where major complications and death are likeliest to occur. The incidence of death from CC-related complications is extremely low in patients under one year of age, compared with death from the underlying lesion or following cardiac surgery.

Age Factors↗
PubMed1985

The use of autografts for vertebral body replacement of the thoracic and lumbar spine.

Thirty-seven patients with fractures of the thoracic or lumbar spine underwent anterior corpectomy (partial or complete) and vertebral body replacement for either destructive lesions from tumor or infection (13 patients) or trauma (24 patients). The vertebral bodies were replaced using either rib (12 patients) or tricortical iliac crest (25 patients) autografts. The Dunn device was utilized in conjunction with the autografts in 19 patients. Posterior stabilization was used in five patients; three prior to anterior stabilization and two after anterior stabilization. Within 2 weeks of the operative procedure, all patients began walking or sitting. Of the 37 patients, 21 with incomplete neurologic deficits improved, and 10 of those went onto complete recovery. Of the 27 patients who have been followed for a minimum of 1 year, 25 have obtained solid fusions, one developed a pseudarthrosis that required regrafting, and one had a delayed union prior to death from metastatic disease. There were two deaths in the immediate postoperative period and three deaths in the first six postoperative wounds due to metastatic disease. The purpose of this study is to present a consecutive series of patients who have undergone corpectomy and vertebral body replacement as well as to define the adequacy of stabilization.

Adolescent↗
PubMed1985

Fetal cardiovascular responses to asphyxia induced by decreased uterine perfusion.

Cardio-respiratory responses to asphyxia produced by decreased uterine perfusion were studied in 15 sheep fetuses. In chronic (spinal-anesthetized) and acute (inhalation-anesthetized) preparations, we measured fetal PO2, PCO2, pH, heart rate, arterial and umbilical venous pressures at rest and 5 min after controlled reductions of maternal aortic blood flow. Umbilical blood flow was determined by electromagnetic flow transducer on the fetal descending aorta with the iliac arteries ligated, in conjunction with radionuclide-labelled microspheres. In contrast to previous studies in which fetal hypoxaemia was produced by decreased maternally inspired O2 concentrations, decreasing degrees of uterine perfusion were associated with increasing degrees of hypercapnea and acidemia, as well as hypoxaemia. In chronic experiments, heart rate and umbilical blood flow fell significantly in response to decreased uterine perfusion with all degrees of hypoxaemia studied. In acute experiments, during the control period, PO2 values were similar to those of chronic experiments while values for pH and umbilical blood flow were lower and those for umbilical vascular resistance were higher. In the acute experiments, hypoxic stresses identical to those in the chronic studies failed to produce significant hemodynamic changes, except for bradycardia in response to severe hypoxaemia. These differences were apparently due to the pharmacologic effects of halothane and the operative stresses.

Anesthesia↗
PubMed1984

Adrenal secretion of catecholamines during hypoxemia in fetal lambs.

A new method for quantifying adrenal secretory function in chronically catheterized fetal lambs was developed. This preparation included insertion of a catheter distally into the fetal left renal vein and placement of a remotely operated, hydraulically controlled choker around the renal vein at its junction with the vena cava. With the choker open, adrenal venous blood flowed into the renal vein and then into the vena cava. With the choker closed, adrenal blood flowed into the catheter so that timed samples of adrenal venous effluent could be obtained. With this technique, left adrenal secretory rates of norepinephrine and epinephrine were determined across a spectrum of oxygen concentrations in five near-term fetal lambs. There was a rapid rise in norepinephrine secretion after induction of hypoxemia. Maximum secretory rates occurred at about 5 min, concomitantly with the lowest attained fetal arterial partial pressure of oxygen (PO2s). There was an inverse exponential relation between these catecholamine secretion rates and fetal arterial PO2 (P less than 0.001). Norepinephrine secretion appeared to increase in response to lesser degrees of hypoxemia than did epinephrine, although a longer time delay between stimulation and epinephrine response may have been a factor. Overall, norepinephrine secretion was greater than that of epinephrine. The ratios of norepinephrine to epinephrine in individual adrenal samples varied considerably and in some instances were less than one. These ratios did not correlate significantly with the degree of hypoxemia. During 25 min of a relatively steady state of hypoxemia, norepinephrine secretion declined markedly after about 5 min, although it remained above control levels throughout. Epinephrine secretion rose more gradually but then was relatively stable during the remaining period of hypoxemia.

Adrenal Glands↗
PubMed1983

Intrathoracic chordoma presenting as a posterior superior mediastinal tumor.

A case of thoracic chordoma successfully treated with surgical excision is reported and described. Thoracic chordomata presenting as posterior superior mediastinal tumors occur infrequently and may be highly malignant lesions. Early radical surgery through thoracotomy provide the best hope of cure, and radiation offers only temporary regression of tumor.

Adolescent↗
PubMed1982

The effect of beta-adrenergic stimulation on fetal cardiovascular function during hypoxemia.

The effect of beta-adrenergic stimulation on fetal cardiovascular function during hypoxemia was studied in six lamb fetuses with gestational ages of 119 to 140 days. In chronic preparations, we determined fetal heart rate, umbilical blood flow (by electromagnetic flowmeter), PO2, PCO2, and pH and calculated fetal cardiac output and organ blood flows (using 15 mu nuclide-labeled microspheres). Observations were made during control periods and periods of hypoxemia, beta-adrenergic blockade by propranolol, and hypoxemia superimposed upon the beta-adrenergic blockade. Beta blockade effected a decrease in fetal heart rate both at rest and with hypoxemic stress. Propranolol produced a fall in cardiac output with hypoxemia, but the meaning of this in regard to beta-adrenergic effects is unclear. Beta blockade did not alter fetal arterial pressure or general blood flow distribution. However, we observed a decrease in umbilical blood flow in response to propranolol under both normoxic and hypoxemic conditions.

Animals↗
PubMed1980

The effect of fetal heart rate on cardiovascular function during hypoxemia.

The effect of heart rate changes on cardiovascular function during hypoxemia was studied in lamb fetuses. In chronic preparations, we determined fetal heart rate, descending aortic blood flow (by electromagnetic flowmeter), PO2, PCO2, and pH and calculated fetal cardiac output (CO) and organ blood flows (with the use of 15 mu nuclide-labeled microspheres). Observations were made during control and hypoxemic states either alone or in the presence of parasympathetic blockade by atropine. Fetuses exposed to moderate hypoxemia (ewe breathing 10% oxygen) developed a significant bradycardia which was prevented by atropine pretreatment; no significant change in CO occurred in either case. Fetuses exposed to severe hypoxemia (8% oxygen) developed bradycardia and a significant decrease in CO; atropine pretreatment prevented the bradycardia but failed to prevent the decrease in CO. Atropine administered to the already severely hypoxemic fetus increased the heart rate but did not restore the depressed CO. The redistribution of blood flow from low-priority (e.g., viscera) to high-priority (e.g., myocardium) tissues correlated with the degree of hypoxemia. Myocardial blood flow was greater during hypoxemia when bradycardia was prevented by atropine than during hypoxemia alone; otherwise, blood flow distribution in response to hypoxemia was unaffected by atropine blockade.

Acetylcholine↗