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Biomedical subjects

J T Robertson

Publications and source records attributed to J T Robertson.

At least 109 records · Page 6Linked to original sources
PubMed1988

Carotid endarterectomy: what is its current status?

The plethora of recent articles regarding carotid endarterectomy has tended to confuse rather than clarify its indications, efficacy, and acceptability. The National Institutes of Health has recently funded two large multicenter controlled clinical trials, one including asymptomatic persons with carotid stenoses, and the other, patients having transient ischemic episodes or minor strokes. Eight academic professors of neurology (four), neurosurgery (two), and vascular surgery (two) with a long and abiding interest in cerebrovascular disease prepared a statement delineating acceptable levels of mortality and morbidity from this procedure. These might serve as guidelines until the large trials have been completed.

Arteriosclerosis↗
PubMed1988

The effect of transportation between the recovery room and intensive care unit on postoperative acoustic tumor patients.

Cardiovascular changes have been noted to occur during movement from the operating room or recovery room (RR) to the intensive care unit (ICU). This study examined blood pressure changes and related variables during transport from the RR to the ICU in 135 postoperative acoustic tumor patients. Although there was no significant change in blood pressure values from the RR to the ICU, patients with pre-existing hypertension and elevated RR blood pressures were noted to have an increased frequency of postoperative complications. In addition, a relationship was noted between administration of halothane and frequency of postoperative complications. Results highlight the need for nurses not only to monitor, but also closely control postoperative blood pressure in this population.

Blood Pressure↗
PubMed1988

Infection-related spontaneous atlantoaxial dislocation in an adult. Case report.

This paper reports the third described case of infection-related atlantoaxial subluxation in an adult. Like most of the similar cases seen in the pediatric literature, this case was associated with a parapharyngeal beta-hemolytic streptococcal abscess. Based upon this experience, the authors advocate intravenous antibiotic therapy and 1) immediate reduction followed by application of a halo brace; 2) immobilization in a halo brace for at least 3 months; and 3) a C1-2 wiring and fusion procedure for patients who fail this trial of conservative therapy.

Abscess↗
PubMed1988

Opioid peptide profile in human pituitary.

The comprehensive metabolic profile of endogenous opioid peptides is established here for human pituitary for the first time. Sixteen human pituitaries, obtained postmortem, were analyzed individually by gradient reversed-phase high-performance liquid chromatography together with a radio-receptor assay with [3H]etorphine as ligand. This combination was used to detect opioid receptor activity. The 16 assay profiles were sufficiently consistent for a composite of them to serve as a comparative basis for other studies on the pathophysiology of the human pituitary. To demonstrate one selected comparison, we present data on a distinctively different profile of opioid receptor activity in the pituitary of one patient who died from a drug overdose.

Adolescent↗
PubMed1987

Congenital sinus cyst in a foal.

Radiography and endoscopy of a 17-day-old Standardbred foal that had right-sided facial swelling and dyspnea since birth revealed a soft tissue mass in the right nasal passage and right maxillary and frontal sinuses. A bone flap was used to expose the mass, and a fluid-filled structure was removed surgically. After surgery, the dyspnea was alleviated. The facial deformity resolved by the time the foal was 6 months old. The upper airway obstruction was absent clinically and endoscopically by the time the foal was 17 months old.

Animals↗
PubMed1987

Pharmacodynamic evaluation of human cerebral arteries in the genesis of vasospasm.

Experiments were performed on isolated human cerebral arteries to evaluate the role desensitization and tachyphylaxis might play in preventing certain agonists from producing prolonged vasoconstriction after subarachnoid hemorrhage. In addition, the antiproteases leupeptin and pepstatin were studied to ascertain whether these peptides might inhibit contraction as does antithrombin III. The maximal contraction to KCl was used as a standard for comparing the responses elicited by the agonists, the decay of the responses to the agonists over 15 minutes was used as an index of desensitization, and the percentage of decrease in response to a second application of the agonist over the first was a measure of tachyphylaxis. The results showed that desensitization and tachyphylaxis greatly reduced or abolished the contractile responses to norepinephrine, serotonin, angiotensin II, arginine vasopressin, substance P, neuropeptide Y, neurotensin, thrombin, uridine triphosphate, linoleic acid, melittin, and cathepsin D. Moreover, some arteries failed to respond to some of these agonists, and no contractile response was elicited by acetylcholine or bradykinin. In contrast, prostaglandins E2, D2, and F2 alpha, as well as plasmin, produced sustained contractions, without tachyphylaxis, but only prostaglandin E2 and plasmin produced contractions at concentrations of 10(-7) M or less that were comparable to those of KCl. None of the antiprotease peptides inhibited the responses to KCl whereas small concentrations (6 X 10(-8) M) of antithrombin III did. The results support the hypotheses that the phenomenon of desensitization and tachyphylaxis would prevent many diverse agents from acting as spasmogens and that substances like antithrombin III present in the cerebrospinal fluid after hemorrhage could immediately protect patients from cerebral vasospasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Tracheal reconstruction in a foal.

A 6-month-old Standardbred foal was admitted for repair of an acquired tracheal deformity. At 2 months of age, 4 midcervical tracheal rings had been transected and, as a result, that portion of the trachea would collapse when the foal became excited or was exercising. At surgery, partial chondrotomies allowed remodeling of the deformed rings, which were then anchored to 2 partially encircling, polypropylene prostheses. After surgical repair, the horse raced successfully.

Animals↗
PubMed1986

Opioid peptides in the cerebrospinal fluid of Alzheimer patients.

Endogenous opioid receptoractive peptides in the cerebrospinal fluid (CSF) of human controls and in those patients diagnosed as having senile dementia of the Alzheimer's type (SDAT) are measured with a radioreceptorassay following HPLC separation. [3H]Etorphine is the ligand used to detect in the HPLC fractions the presence of those endogenous peptides that preferentially interact with several opioid receptors. The RRA uses a receptor-rich P2 fraction extracted from a canine limbic system. The total opioid peptide content found in the HPLC fractions 6-20 (to avoid salts in fractions 1-5) of SDAT CSF (383 +/- 187 pmol ME-equivalents per ml CSF) is significantly higher than the corresponding total from patients with no known neurological disorders (89.1 +/- 46.3 pmol ME-equivalents per ml).

Aged↗
PubMed1986

Surgical treatment of cerebrovascular occlusive disease.

Surgical therapy for cerebrovascular occlusive disease has a rich and fascinating history. Carotid endarterectomy is the most commonly performed operation for cerebrovascular disease. Other ingenious efforts have been tried and, of these, only the superficial temporal middle cerebral artery bypass procedure has been prospectively studied. All efforts at extracranial and intracranial vascular surgery are under scrutiny presently and many feel that the extracranial-intracranial bypass procedure has little, if any, future. The efficacy of carotid endarterectomy will probably be studied prospectively, but, for the immediate future, endarterectomy is a well-established therapy for certain cases of carotid stenosis or ulceration.

Carotid Artery Diseases↗
PubMed1985

Metabolic profiling of radioreceptor-assayable opioid peptides in a human pituitary ACTH-secreting tumor.

The profile of endogenous opioid peptides in the peptide-rich fraction obtained from a homogenate of an ACTH-secreting human pituitary tumor is presented. Gradient RP-HPLC is used to separate the mixture into peptide constituents. A preparation of opioid receptors is used in a radioreceptor assay with ethorphine - a relatively non-specific ligand that is used as a screen because it interacts with mu, sigma, and delta receptors - as the HPLC detector to detect a range of peptides that derive from proenkephalin A and POMC.

Adrenocorticotropic Hormone↗
PubMed1985

Contribution of the nasal septum to the radiographic anatomy of the equine nasal cavity.

The radiopacity of the equine cartilaginous nasal septum and its covering mucosa seen on dorsoventral radiographs was determined to be of sufficient density to be useful in the diagnosis of any disorder of this anatomic structure. Radiographically, the frontal and nasal bones dorsally and the vomer and palatine process of the incisive bone ventrally do not completely obscure the nasal septum and its covering mucous membrane.

Animals↗
PubMed1985

Evaluation of the efficacy of intrathecal nimodipine in canine models of chronic cerebral vasospasm.

Previous studies have examined whether calcium antagonists given sublingually, intravenously, or orally affect an experimentally induced vasospasm. This study was designed primarily to determine the efficacy of nimodipine given intracisternally in reversing the cerebral vasospasm produced in dogs by the injection of 4 ml of autogenous blood into the cisterna magna. The magnitude of the vasospasm and the vascular response to nimodipine were determined arteriographically. One group of animals was studied acutely to determine the dose and pharmacodynamic effects of intrathecal nimodipine, a second group was studied 1 to 4 days after the intrathecal injection of blood, and a third group was studied 3 to 6 days after successive injections of cisternal blood given 48 hours apart. Some animals were studied further 24 hours after the nimodipine treatment. Intrathecal administration of 4 ml of 10(-3) M nimodipine promptly and completely reversed the cerebral vasospasm in all groups. This effect lasted at least 4 hours but had disappeared by 24 hours. The intrathecal administration of nimodipine produced a transient drop in blood pressure. In contrast, nimodipine given sublingually (0.28 to 0.58 mg/kg) or intravenously (0.1 mg/kg) produced a persistent hypotensive effect without affecting the vasospasm. The results show that the presence of nimodipine in the cerebrospinal fluid will reverse the blood-induced vasospasm, and suggest that this calcium antagonist administered intrathecally would be an effective emergency treatment of cerebral arterial spasm.

Animals↗
PubMed1985

Role of plasmin, thrombin, and antithrombin III as etiological factors in delayed cerebral vasospasm.

The fibrinolytic enzyme plasmin at 0.25 units/ml produced a contraction of isolated canine basilar arteries that developed slowly and was sustained for at least 2 hours. Plasmin and thrombin (1 unit/ml) acted synergistically to enhance the contractile response. In contrast to plasmin, the marked contraction elicited by thrombin ended within 1 hour, and afterward the artery was completely tachyphylactic to thrombin. Fibrin clot, fibrinopeptides, and fibrin degradation products did not prolong significantly the effect of thrombin or prevent the tachyphylaxis. Plasmin and thrombin may occupy a common membrane receptor because exposing the artery briefly to trypsin (24 micrograms/ml) thereafter abolished the contractile effect of plasmin and thrombin without affecting the action of other agonists. Antithrombin III (1.0 unit/ml) relaxed basilar arteries that were precontracted with plasmin (0.5 unit/ml), thrombin (1.0 unit/ml), serotonin (10(-5) M), uridine triphosphate (10(-4) M), or KCl (8 X 10(-2) M). The results suggest that the vasoconstrictor effect of thrombin might contribute to hemostasis after subarachnoid hemorrhage (SAH) but, because of tachyphylaxis, not to delayed vasospasm. On the other hand, the constrictor action of plasmin might appear late in the course of SAH in association with clot lysis and tissue repair. Last, the level of the vasorelaxant antithrombin III in cerebrospinal fluid could control the appearance and severity of cerebral arterial spasm in SAH.

Aminocaproic Acid↗
PubMed1985

Comparison of three suture techniques for anastomosis of the small intestine in the horse.

Seven horses were used to compare the Gambee, the crushing, and a 2-layer inverting suture pattern composed of a simple continuous layer in the mucosa oversewn with a continuous Lembert pattern in the seromuscular layer. Horses were evaluated at 30 days for adhesion formation, lumen diameter, and quality of healing at the anastomotic sites. One horse was euthanatized 9 days after surgery after 24 hours of ileus and colic; necropsy revealed septic peritonitis and widespread adhesions. One horse had no adhesions. The remaining horses had adhesions associated with 50% of the Gambee and 50% of the crushing anastomoses. There were no adhesions related to the 2-layer inverting techniques in these 6 horses. There was no significant difference in percentage reduction of lumen diameters between the 3 techniques, and there was no evidence of chronic obstruction resulting from any of the anastomotic techniques. Histologically, the inflammatory response and fibrosis were minimal in the single layer patterns, but there was increased fibrosis and suture tract inflammation in the 2-layer inverting technique.

Anesthesia, General↗