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Biomedical subjects

R E Brashear

Publications and source records attributed to R E Brashear.

At least 19 recordsLinked to original sources
PubMed1988

Effect of alteration of cerebrospinal fluid bulk flow on nicotine cerebrospinal fluid exit transfer kinetics.

This study was undertaken to determine if a compound which alters the bulk flow of cerebrospinal fluid (CSF) alters the elimination kinetics of a compound in the CSF. Acetazolamide was chosen as the CSF bulk flow-altering agent. It produces a relatively large effect on the flow process, affecting both choroidal and extrachoroidal CSF production, and has been shown to affect CSF flow following iv administration. The compound monitored was nicotine. Acetazolamide was administered orally for one week before and intravenously during the experiment. Nicotine was administered by a bolus injection directly into the CSF via the cisterna magna. The results indicate that the introduction of acetazolamide into the general circulation increases the rate of removal of nicotine from the CSF. Subjects receiving acetazolamide had elevated CSF pressures. The increase in CSF pressure associated with the administration of acetazolamide suggests pressure as a possible factor in the observed increase in the rate of removal of nicotine.

Acetazolamide↗
PubMed1987

Esophageal fistula complicating mediastinal histoplasmosis. Response to amphotericin B.

A 41-year-old man was admitted for evaluation of hemoptysis, dysphagia, and pleuritic chest pain associated with a mediastinal mass. Esophagography demonstrated a fistula between the mass and the esophagus. Results of histoplasmosis complement fixation serologic testing suggested an active infection. A methenamine silver stain of a lymph node obtained at mediastinoscopy revealed Histoplasmosis capsulatum. The patient was successfully treated with amphotericin B. This is believed to be the first reported case of an esophageal fistula as a complication of mediastinal histoplasmosis successfully treated with amphotericin B.

Adult↗
PubMed1985

Cystic fibrosis. An adult perspective.

We treated a patient with an unusual case of cystic fibrosis in whom the diagnosis was not made until age 42 years, the predominant clinical manifestation was recurrent pancreatitis, and the chest roentgenogram and results of pulmonary function tests were normal between bouts of pneumonia. As cystic fibrosis may simulate more benign conditions often seen in adults, the diagnosis must be suspected and confirmed for optimal management. Internists must play an increasingly important role in the diagnosis and management of this disease.

Adult↗
PubMed1985

Activated charcoal in theophylline intoxication.

To test the hypothesis that orally administered activated charcoal alters the elimination kinetics of intravenously administered theophylline, six dogs were twice infused with theophylline, 28 mg/kg, over 20 minutes 1 week apart. In a random sequence separated by 1 week, they received either activated charcoal, 30 gm in a water suspension or water only through a nasogastric tube every 2 hours after theophylline infusion, for a total of four doses. The time needed for plasma levels to fall below 20 mg/L was approximately 5 hours regardless of charcoal treatment. However, activated charcoal decreased theophylline halflife from 4.02 to 2.76 hours and volume of distribution from 0.72 to 0.61 L/kg. We conclude that although activated charcoal hastened the elimination of theophylline in dogs, the usefulness of orally administered activated charcoal in the treatment of theophylline overdose may be limited by the inability to shorten the time during which plasma levels are toxic.

Administration, Oral↗
PubMed1984

Arrhythmias in patients with chronic obstructive pulmonary disease.

Cardiac arrhythmias are commonly associated with chronic obstructive lung disease and these arrhythmias can impair arterial blood oxygenation. The etiology of the arrhythmias is multifactorial. The treatment of the arrhythmias is largely the treatment of the deranged physiology and the underlying pulmonary disease. The association of arrhythmias with chronic obstructive lung disease portends a poor prognosis.

Anti-Arrhythmia Agents↗
PubMed1984

Clearance and metabolism of plasma pyridoxal 5'-phosphate in the dog.

This study was undertaken to characterize the metabolic fate of plasma pyridoxal 5'-phosphate (pyridoxal-P), the role of various organs in mediating its degradation, and the contribution of urinary excretion. Anesthetized dogs underwent sham operation, hepatectomy, nephrectomy, or combined surgical removal of the stomach, small intestine, and the spleen; however, the kinetics of plasma pyridoxal-P clearance after the intravenous administration of 2.5 mg of this B6 vitamin were not altered. In anesthetized sham-operated dogs and in unanesthetized dogs, pyridoxal (product of pyridoxal-P hydrolysis) but not 4-pyridoxic acid (oxidation product of pyridoxal) accumulated in plasma and urine after pyridoxal-P administration. Urinary excretion of pyridoxal-P was negligible and it could not account for the rapid clearance of pyridoxal-P from the plasma. The rate of pyridoxal-P hydrolysis mediated by plasma alkaline phosphatase and the cellular elements in whole blood in vitro was also too slow to account for the rapid disappearance of plasma pyridoxal-P in vivo. These results indicate that (1) normally, the overall capacity of the body to hydrolyze circulating pyridoxal-P in plasma is so large that removal of the liver, kidneys, or the intestinal tract and spleen has little or no effect on the rate of plasma pyridoxal-P decay; and (2) plasma pyridoxal-P decay normally proceeds by way of hydrolysis to form pyridoxal. Because pyridoxal is not further oxidized by the liver and the amount of pyridoxal excreted in the urine accounts for less than 25% of the pyridoxal that can be derived from the injected pyridoxal-P load, the preponderant metabolic fate of plasma pyridoxal-P most likely involves its hydrolysis to pyridoxal and then the uptake of pyridoxal by extrahepatic tissues.

Alkaline Phosphatase↗
PubMed1983

Theophylline blood-brain barrier transfer kinetics in dogs.

A simple diffusion-based pharmacokinetic model is proposed relating blood-brain barrier transfer kinetics of theophylline to the difference in the free concentrations of the drug in serum and cerebrospinal fluid (CSF). The model predicts that the CSF drug level is proportional to the serum drug level convoluted by exp(-kt), where k is the blood-brain barrier diffusion rate constant. An excellent agreement was found by nonlinear regression analysis between serum and CSF theophylline data in eight dogs and the proposed model for the blood-brain barrier transfer kinetics of theophylline. The ratio of the free fractions of theophylline in serum and CSF predicted from the model also agrees with the value determined experimentally.

Animals↗
PubMed1983

Diffusion and flow transfer of theophylline across the blood-brain barrier: pharmacokinetic analysis.

Two possible schemes describing the transfer of theophylline across the blood-brain barrier are investigated. The first, the "diffusion only model," assumes that the rate of transfer is proportional to the difference in free drug concentration in the serum and cerebrospinal fluid. The second, the "diffusion and flow model," has the added feature that drug may be transferred from the CSF to the blood by the continuous secretion of CSF into the blood. Comparison of the results of nonlinear regression for the two proposed schemes indicated that the "diffusion and flow" model best describes the transfer process. The analysis indicates that the parameters obtained for the "diffusion and flow" model are physiologically meaningful.

Animals↗
PubMed1983

The ventilatory response to intravenous and ventriculo-cisternal theophylline.

The stimulatory effect of theophylline on ventilation was studied in nine anesthetized dogs. Theophylline infused intravenously (10 mg/kg bolus, then 1.00 mg/kg/hr) for 210 minutes significantly increased the minute volume of ventilation (P less than 0.05 at 210 minutes). After a recovery period of seven to fourteen days, ventriculo-cisternal perfusion was performed with mock cerebrospinal fluid (CSF). Theophylline added to the mock CSF did not significantly change the minute ventilation. ventriculo-cisternal perfusion utilizing mock CSF not containing theophylline combined with intravenous theophylline infusion stimulated ventilation similarly to the previous intravenous theophylline infusion. Therefore, stimulation of ventilation by theophylline appears to relate to the serum theophylline concentration and not the ventricular CSF theophylline concentration.

Aminophylline↗
PubMed1983

Pulmonary infiltrates following butane 'fire-breathing'.

Rapidly progressive bilateral pulmonary infiltrates occurred in a 19-year-old man following an unusual hydrocarbon abuse. The acute illness was the result of a "trick" known as "fire-breathing." Fire-breathing involves filling the oral cavity with butane gas, from an ordinary butane cigarette/cigar lighter, and exhalation of the volatile vapors over an open flame producing a flame-throwing effect. Because of the pulmonary toxic reaction, this activity could have a serious or even fatal outcome.

Adult↗
PubMed1983

Pleural effusion in a young woman with myxedema.

Untreated myxedema occurred with bilateral pleural effusions. There are 13 previous cases reported in the literature. This unusual finding may be the most obvious manifestation of hypothyroidism, and this association can be an important clue in diagnosing an unexplained pleural effusion.

Adult↗
PubMed1982

Cough: diagnostic considerations with normal chest roentgenograms.

Cough is the second most frequent symptomatic reason given by patients visiting office-based physicians. The patient with cough and normal chest roentgenograms requires further evaluation in addition to a detailed history, careful general physical examination, meticulous otorhinolaryngology examination, and posterior-anterior and lateral chest roentgenograms. Additional studies may need to include bronchoscopy, paranasal sinus roentgenograms, pulmonary function tests (with possible inhalation challenge and exercise studies), biopsy of lung parenchyma, assessment for gastroesophageal reflux, esophogram, bronchography, echocardiography, and consideration of psychiatric factors.

Adult↗