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Biomedical subjects

J D Cooper

Publications and source records attributed to J D Cooper.

At least 307 records · Page 17Linked to original sources
PubMed1982

Rapid assay for amino acids in serum or urine by pre-column derivatization and reversed-phase liquid chromatography.

This method for estimating clinically important amino acids in serum or urine within 40 min involves o-phthalaldehyde/2-mercaptoethanol derivatization and reversed-phase "high-pressure" liquid chromatography. Homocysteic acid is an internal standard, and homoserine and norvaline are reference peaks. For all the amino acids estimated, the between-run coefficients of variation ranged from 2.0 to 13.5%, and the mean analytical recoveries from both serum and urine samples was 101%. Peak areas vary linearly with concentration up to 1500 mumol/L for all the amino acids assayed. The limit of detection for each amino acid was estimated to be 38 fmol.

Amino Acids↗
PubMed1981

Aspiration needle biopsy of thoracic lesions.

We reviewed our experience with 2,114 percutaneous aspiration needle biopsies of intrathoracic lesions. Aspiration was performed for cytological diagnosis employing biplane fluoroscopy and a 20 gauge needle, 0.9 mm in outside diameter. A satisfactory specimen was obtained in 88% of biopsies, and the chance of obtaining a correct diagnosis of a malignant lesion was 81.5%. The false positive rate was 2.3%, and the cytologists could always distinguish between primary and secondary neoplasms. A false negative rare of 13.6% (36 patients) resulted in only three delayed thoracotomies and two instances of interval metastases discovered at mediastinoscopy. Cellular specificity in primary tumors was not sufficiently accurate to affect therapy. Pneumothoraces occurred frequently (31.9% of patients) but wee generally small; 10.4% of patients required chest drainage. There were no recorded instances of tumor implantation in needle tracts. We conclude that a rapid and accurate diagnosis of intrathoracic pathology can be obtained by this technique. It is associated with an acceptable morbidity and may greatly expedite both patient care and investigation.

Biopsy, Needle↗
PubMed1981

Gastroesophageal reflux: medical and surgical management.

The assessment of gastroesophageal reflux requires a carefully taken history and appropriate selection of the relevant diagnostic tests from among the many such tests available. Gastroesophageal reflux is generally produced by an imbalance between the intragastric pressure on the one hand and the degree of competence of the lower esophageal sphincter on the other. Medical management incorporates measures designed to promote gastric emptying, augment the resting tone of the lower esophageal sphincter, and favorably alter the nature of the refluxed material by dietary and pharmacological means. The surgical techniques commonly applied for the prevention of gastroesophageal reflux aim to restore an intraabdominal segment of esophagus and to augment sphincter competence by either a partial or complete fundoplication. Comparison of results obtained with various operations is difficult, as assessment is often imprecise, subjective, and partisan. Development of a uniform method of postoperative assessment, free from observed bias, would be a major advance.

Esophagoscopy↗
PubMed1981

Supradiaphragmatic ligation of the thoracic duct in intractable chylous fistula.

Spontaneous closure of a chylous fistula is usual, but the rare intractable fistula may lead to disastrous nutritional and immunological consequences. We report the surgical management of 5 patients with intractable fistulas with daily drainage averaging 2,060 ml. Conservative therapy failing, the 5 patients underwent 6 ligations of the thoracic duct. A limited posterolateral thoracotomy was used in 3, full right thoracotomy in 2, and left thoracotomy in 1. Ligations were carried out immediately above the diaphragm, and not at the fistula site, by a mass ligature technique encircling all tissue between the azygos vein and aorta. The ligation achieved immediate cessation of drainage in four of five initial procedures and in the fifth patient, at a second operation. High-output thoracic duct fistulas may be handled by supradiphragmatic ligation of the thoracic duct. Identification of the fistula site or the dissection of the thoracic duct itself is avoided by this technique.

Aged↗
PubMed1981

Critical dependence of respiratory rhythmicity on metabolic CO2 load.

We examined the dependence of respiratory rhythm generation on the rate of CO2 production (VCO2) in six awake sheep using a venous-to-venous extracorporeal perfusion circuit that included two carbon dioxide membrane lungs (CDML) designed to facilitate the removal of CO2 from blood. As progressively greater proportions of the resting VCO2, of the sheep were removed from the venous blood by the CDML, there were proportional reductions in pulmonary CO2 excretion and in minute volume of ventilation (VE); when CO2 was removed by the CDML at a rate equal to its metabolic production by the sheep, VE fell to zero, with normal values of arterial PCO2, pH, and PO2. The results indicate that effective respiratory rhythm generation is critically dependent on stimuli related to VCO2.

Animals↗
PubMed1981

Carotid chemoreceptors in ventilatory responses to changes in venous CO2 load.

We examined the role of the carotid chemoreceptors in the ventilatory response to changes in venous CO2 load in 12 awake sheep using a venovenous extracorporeal perfusion circuit and two carbon dioxide membrane lungs (CDML). Three of the sheep had undergone surgical denervation of the carotid bodies (CBD). In the nine intact sheep, as CO2 was removed from or added to the peripheral venous blood through the CDML under normoxic conditions, there was a linear relationship between the rate of pulmonary CO2 excretion (VCO2) and the resulting rate of ventilation over a VCO2 range of 0--800% of control, so that arterial PCO2 remained close to isocapnic. In contrast, in the three CBD sheep, the ventilatory response to changes in VCO2 was significantly decreased under normoxic conditions, resulting in marked hypercapnia. The results indicate that the carotid chemoreceptors exert a major influence on the ventilatory response to changes in venous CO2 load.

Animals↗
PubMed1981

Preservation of platelets during extracorporeal circulation in sheep. A comparison between aspirin and sulfinpyrazone.

We studied the effect of aspirin and sulfinpyrazone on changes in platelet count, thromboxane B2 production, and pulmonary vascular resistance following the onset of veno-venous membrane oxygenator perfusion in sheep. Perfusion under identical circumstances was performed in three groups of animals, with one group serving as controls, one group receiving pretreatment with 1.5 grams of sulfinpyrazone iv, and one group receiving pretreatment with aspirin 50 mg/kg, iv. Both aspirin and sulfinpyrazone eliminated the rise in thromboxane B2 and the increase in pulmonary vascular resistance seen in control animals. Platelet preservation was improved significantly with sulfinpyrazone pretreatment, but not affected by aspirin. We conclude that sulfinpyrazone and aspirin have different mechanisms of action as far as platelet preservation during extracorporeal perfusion is concerned. The major difference may be sulfinpyrazone's ability to reduce platelet adhesion to the membrane surface. Since both aspirin and sulfinpyrazone eliminated the pulmonary vascular-response, but only sulfinpyrazone preserved platelets, it is apparent that the pulmonary vascular response is more closely related to thromboxane synthesis than to platelet disappearance.

Animals↗
PubMed1981

Role of metabolic CO2 production in ventilatory response to steady-state exercise.

We examined the role of metabolic CO2 production in the hyperpnea of muscular exercise by comparing the response of alveolar ventilation to moderate levels of exercise with the response to venous infusion of CO2 at rest. Studies were performed in four awake sheep that were trained to run on a treadmill. The sheep had been cannulated for veno-venous extracorporeal perfusion so that CO2 could be infused into the peripheral venous blood through membrane lungs in the perfusion circuit. The sheep breathed room air through an endo-tracheal tube inserted through a tracheostomy, and samples of expired gas were collected for measurement of the rates of CO2 production and O2 consumption. All measurements were made in the steady state. In each of the four sheep, the relationship between alveolar ventilation and the rate of CO2 production could be described by a single linear function (r greater than 0.99; P less than 0.001), regardless of whether CO2 production was increased by exercise, venous CO2 infusion, or combinations of both procedures. This relationship applied for values of CO2 production up to 350% of control. In contrast, no unique relationship was found between the rate of alveolar ventilation and either the rate of O2 consumption, cardiac output, or mixed venous blood gas pressures. The findings indicate that the hyperpnea of mild to moderate steady-state exercise can be attributed to the associated increase in the rate of CO2 production. Therefore, there is no need to invoke obligatory nonmetabolic stimuli to account for the ventilatory response to steady-state exercise.

Animals↗
PubMed1981

The palliative value of surgical resection for carcinoma of the esophagus.

The authors review their experience with primary resection for carcinoma of the esophagus and compare the palliative results with those of a recently reported series of similar patients treated with radiotherapy alone. Between 1971 and 1977, 104 patients with carcinoma of the esophagus underwent resection as the primary therapy. The operative mortality was 7.7% (1.7% in the latter half of the series). At least 80% of the 104 patients had complete, continuing palliation of their dysphagia. Radiotherapy in a similar group of patients reported resulted in an 8% mortality from complications of the treatment and there was local recurrence of the tumour, usually associated with dysphagia, in 80%. The authors conclude that the palliation achieved with surgical resection is substantially better than that achieved with radical radiotherapy applied to a similarly staged group of patients with carcinoma of the esophagus.

Adenocarcinoma↗
PubMed1981

Prospective, randomized, double-blind study using prophylactic cephalothin for major, elective, general thoracic operations.

A total of 211 patients were entered into a randomized, double-blind study of postoperative infection in which an antibiotic (cephalothin) and a placebo were used. The antibiotic was effective in reducing sleep wound infections (p less than 0.05) and superficial wound infections (p less than 0.01). The incidence of pulmonary infections was decreased, but the change was not statistically significant, and the incidence of empyema was unaffected.

Bacterial Infections↗
PubMed1981

Effects of methylprednisolone and azathioprine on bronchial healing following lung autotransplantation.

The effect of low-dose immunosuppressive therapy upon the healing of the bronchial anastomosis and skin wound following lung autotransplantation was evaluated. Autotransplantation was performed in two groups of dogs: Group 1 (15 dogs) received no immunosuppression and Group 2 (13 dogs) received postoperative immunosuppression with methylprednisolone (2 mg/kg) and azathioprine (1.5 mg/kg). Two to four skin incisions 7 cm in length were made in the dorsal region of each dog. Dogs were put to death at 4, 9, 16, and 23 days postoperatively and the bronchial anastomoses and skin wounds were evaluated by breaking strength measurements. Bronchus and skin breaking strength increased with time in both groups. Bronchus breaking strength was similar in the two groups at day 4 and day 9. However, by day 23 bronchus breaking strength was significantly higher in Group 1 (p less than 0.001). Skin breaking strength was significantly higher in Group 1 on days 9 and 16 (p less than 0.005) and on day 23 (p less than 0.001). Our results suggest that low-dose methylprednisolone and azathioprine significantly affect the breaking strength of both bronchial anastomoses and healing skin incisions following canine lung autotransplantation.

Animals↗
PubMed1981

Use of the silicone tracheal T-tube for the management of complex tracheal injuries.

This paper reports on the use of the silicone Montgomery T-tube for the management of 18 patients with complex tracheal injuries. Our use of the tube was as follows: prior to definitive resection, as a better alternative to tracheostomy tube, while we were awaiting the most appropriate time for resection; at the time of resection, as an adjunct to segmental subglottic resection, used to stent residual abnormal laryngeal mucosa: following tracheal resection for uncertain or unsatisfactory healing: as sole treatment, when resection was deemed unsuitable or inappropriate. When stenting the high region, the upper limb of the T-tube can be brought through the vocal cords with preservation of a functional voice and without injury to the vocal cords even with prolonged use. In contrast to a tracheostomy tube, the T-tube provides respiration through the the nasopharynx, so that humidification and phonation are maintained. It is generally trouble free, requires little if any maintenance, and can remain in place for a year or more when necessary.

Adolescent↗
PubMed1981

Developmental bronchopulmonary disease in adults: practical clinical considerations.

Developmental abnormalities of the tracheobronchial tree and its vascular components may be seen in both pediatric and adult patients. These abnormalities occur as pure bronchial anomalies (in which the vascular organization is normal), as pure vascular anomalies (in which the bronchial arborization has proceeded normally) or as combined bronchial and vascular anomalies. The clinical syndromes associated with these anomalies may usefully be considered together as different aspects of potential failure of bronchovascular development. In the adult the bronchogenic cyst is the most commonly encountered pure bronchial abnormality, arteriovenous malformation the commonest pure vascular anomaly and sequestration the most frequent mixed defect. Between 1958 and 1978, 32 bronchogenic cysts, 14 sequestrations and 18 parenchymal aneurysms were treated at the Toronto General Hospital. Diagnostic and therapeutic considerations suggest that surgical intervention is warranted in most cases.

Adolescent↗
PubMed1980

Pulmonary leukostasis and its relationship to pulmonary dysfunction in sheep and rabbits.

Pulmonary leukostasis, as a result of complement activation, has been invoked as a cause of pulmonary dysfunction. To investigate this phenomenon, we studied the pulmonary response to infusion of autologous complement-activated plasma in sheep and rabbits. Complement activation was produced by plasma incubation with zymosan. Leukopenia, with selective loss of polymorphonuclear leukocytes into the lungs, occurred in all animals immediately after the onset of plasma infusion. Complement-activated plasma infusion in sheep produced a significant fall in the arterial PO2 and a marked rise in pulmonary vascular resistance, whereas no such effects were observed in rabbits. Pretreatment of the sheep with sulfinpyrazone eliminated the pulmonary response to complement-activated plasma without altering the leukopenic response. Pulmonary histology in rabbits and sheep confirmed the presence of intracapillary leukostasis after the plasma infusions, whether or not sulfinpyrazone had been administered previously. The pulmonary response to complement activation is associated with pulmonary capillary leukostasis, but leukostasis alone is not an adequate explanation of the phenomenon.

Animals↗
PubMed1980

A rapid method for the determination of perhexiline in serum using gas-liquid chromatography.

A rapid method for the estimation of perhexiline in serum is presented. The procedure employs a single extraction, and no derivatisation is required. The procedure is linear over the range 0.4-4.0 mg/l, and the limit of detection is 0.09 mg/l. The within- and between-batch coefficients of variation at a concentration of 2.0 mg/l were 2.5 and 4.1%, respectively. Recoveries over the range 0.4-4.0 mg/l produced a mean of 104%. The method is free from interference by other common drugs used in the treatment of angina.

Adrenergic beta-Antagonists↗
PubMed1980

Human lung transplantation.

The 38th attempt at allotransplantation of a human lung is described in a patient with injury due to smoke inhalation. The innovative features in the procedure included prolonged support with an extracorporeal membrane oxygenator during and for four days following transplantation, pharmacologic control of platelet function with sulfinpyrazone, continuous monitoring with a fiberoptic ear oximeter, and pretreatment of the transplanted lung with cytotoxic durgs. The patient survived until the 18th postoperative day, with no evidence of tissue rejection, but he died following ischemic disruption of the bronchial anastomosis. We conclude that the major determinant in the future of human lung transplantation is related to the establishment of a bronchial arterial supply to the transplanted bronchus.

Adolescent↗