Search PubMed⌕ Search

Biomedical subjects

R R Gray

Publications and source records attributed to R R Gray.

At least 55 records · Page 3Linked to original sources
PubMed1992

Induced release of acetylcholine from guinea pig ileum longitudinal muscle-myenteric plexus by anatoxin-a.

Anatoxin-a (ANTX), a nicotinic agonist, has been shown to induce contraction of guinea pig ileum, which was abrogated by the muscarinic antagonist atropine and the nicotinic antagonists tubocurarine and hexamethonium. We showed here that the ganglionic nicotinic antagonist mecamylamine was a better inhibitor of the contraction of ileum induced by ANTX. The sodium channel blocker tetrodotoxin also abolished ANTX-induced contraction. In contrast, alpha-bungarotoxin, the muscle type nicotinic receptor blocker, had no effect on ANTX-induced contraction of guinea pig ileum. Longitudinal muscle-myenteric plexus prepared from guinea pig ileum, labeled with [3H]choline and then incubated with ANTX was shown for the first time to release [3H]acetylcholine (ACh) in a dose-dependent manner. Pretreatment of longitudinal muscle-myenteric plexus with tubocurarine, hexamethonium or mecamylamine blocked ANTX-induced release of [3H]ACh. In contrast, atropine was without effect. Mecamylamine was the most potent antagonist. As observed in ileum contraction, tetrodotoxin completely and potently blocked the release of [3H]ACh induced by ANTX. Neither alpha-bungarotoxin nor the neuromuscular junction blockers conotoxin G1 or M1 could inhibit the [3H]ACh release. Taken together, these results suggested that ANTX activated nicotinic receptors on ganglionic interneurons to trigger a release of ACh, which next stimulated muscarinic receptors and induced ileum contraction.

Acetylcholine↗
PubMed1991

Intravenous digital subtraction arteriography in the evaluation of vascular grafts.

Between 1982 and 1986 intravenous digital subtraction arteriography was used to evaluate vascular grafts in 97 patients (54 males, 43 females). Indications included recurrent symptoms, absent or diminished pulses, a drop in Doppler pressure measurements, and clinical uncertainty with respect to graft patency. Problems identified included graft stenosis, stenosis of the anastomosis or its distal vessels, false aneurysm, arteriovenous fistula and emboli. Forty-eight operations were carried out following intravenous digital subtraction arteriography, and radiographic findings were verified surgically. Twice, intravenous digital subtraction arteriography did not show significant graft findings which were discovered at surgery. Thus intravenous digital subtraction arteriography showed a sensitivity of 95.8% and specificity of 100%. Complications following intravenous digital subtraction arteriography were: two patients developed urticaria, and one superficial thrombophlebitis. There were no cases of pulmonary edema or death. In conclusion intravenous digital subtraction arteriography is very useful in the diagnosis of graft-related problems if done on a selective basis looking at graft and anastomosis site only. Intravenous digital subtraction arteriography is done on an outpatient basis, has high sensitivity and specificity, good patient acceptance, is safe, fast and is less expensive than conventional arteriography.

Adult↗
PubMed1989

Unusual tubular calcification of a nephrostomy tract.

Unusual tubular calcification occurred in the nephrostomy tract of a 30-year-old male, 6 months after percutaneous nephrostolithotomy. To our knowledge, this phenomena has not been previously reported. The main radiologic differential diagnoses are focal dystrophic calcification and vascular calcification. The etiology is unknown but may have been related to the patients' tendency to form renal calculi. The temporal sequence of events and the location of the nephrostomy catheter which correlated with the calcification suggests the correct diagnosis.

Adult↗
PubMed1989

Modified catheter for percutaneous gastrojejunostomy.

A catheter for gastrojejunostomy was modified to include a Cope-loop retention device in the proximal part of the catheter and multiple side holes in the distal part. The modification was made to prevent catheter dislodgment, which can lead to infusion of feeding solution into the peritoneum. The catheter has been used successfully in 71 patients, and only minor complications have been reported.

Adult↗
PubMed1989

Nonoperative management of complications of percutaneous renal nephrostomy.

Between 1984 and 1986 at the Wellesley Hospital in Toronto, 210 percutaneous renal nephrostomies were performed for drainage and 140 were done to provide access for nephrolithotomy. Less than 2% of the patients experienced complications requiring intervention and less than 0.5% required an open surgical approach for the management of procedure-related problems. Complications that were managed conservatively included splenic puncture, false aneurysm, laceration of the renal artery, arteriovenous fistula, hemorrhage requiring transfusion, pneumothorax-empyema, urinoma, septic shock and the hemolysis-hyponatremia-renal shutdown syndrome.

Adult↗
PubMed1988

Pancreatic pseudocysts drained through a percutaneous transgastric approach: further experience.

Percutaneous transgastric placement of a drainage catheter under ultrasonographic and fluoroscopic guidance was performed in 12 patients with pancreatic pseudocysts. Complete resolution of the pseudocysts was obtained in eight patients, and the result was indeterminate in one patient due to early death from unrelated causes. Surgical intervention followed in two patients, one with a multiloculated pseudocyst that was incompletely drained and another with a pseudocyst that became infected following drainage. In one patient with metastatic tumor to the head of the pancreas the pseudocyst resolved initially, but a pseudocyst later recurred. There were no pancreaticocutaneous fistulas or other major complications. The transgastric route of pseudocyst drainage is safe and effective, and it offers a low risk of recurrence and fistula formation.

Adult↗
PubMed1988

Oophorovesicular-colonic fistula: a rare complication of Crohn's disease.

Salpingitis and vesicular fistulas are rare complications of Crohn's disease. In this report the authors describe a case of oophorovesicular-colonic fistula secondary to Crohn's disease. The patient presented with bleeding from the bladder during menstruation, fecaluria and pneumaturia. A single-stage left salpingo-oophorectomy, sigmoid resection and repair of the fistula were carried out, with complete resolution of symptoms and preservation of fertility potential.

Adult↗
PubMed1987

Percutaneous gastrostomy and gastro-jejunostomy.

Percutaneous gastrostomy and gastro-jejunostomy are new techniques which may be used instead of surgical or endoscopic gastrostomy to feed patients with an intact small bowel. We have successfully performed 72 gastrostomies on 67 patients who had had unsuccessful procedures and required surgery. Two patients developed peritonitis when their catheter dislodged into the peritoneal space.

Adult↗
PubMed1987

The role of CT and DSA in cranial sino-venous occlusion.

Twenty-three patients with a clinical and a radiological diagnosis of cranial sino-venous occlusion (CSO) were randomly assembled and selectively studied in a retrospective manner. Eleven instances were related to the presence of a meningioma and 12 were not. Patients in the meningioma group were older and had a better prognosis than the patients in the nonmeningioma group, but angiography was still necessary in all those with meningioma to diagnose CSO, whereas computed tomography (CT) was most helpful in permitting the diagnosis in the nonmeningioma group. The most frequent CT abnormality seen in this latter group was the "delta" or empty triangle sign (75% of scans), followed by cerebral edema (42%) and venous infarction (33%). One patient had a normal scan. The recent availability of intravenous digital subtraction angiography has helped confirm the diagnosis in a faster, safer and more reliable way. Careful interpretation of CT, especially in patients with CSO unrelated to meningioma, may result in decreased morbidity and mortality as a result of earlier diagnosis and treatment.

Cerebral Angiography↗
PubMed1987

Percutaneous conversion of surgical gastrostomy to jejunostomy: indications and technique.

Should a surgical gastrostomy prove to be inappropriate it can readily be converted to a jejunostomy using standard percutaneous techniques. We have used this technique in six patients with gastro-esophageal reflux, four with gastric perforation, two with gastric outlet obstruction, two with duodenal perforations, and two patients with gastrostomy breakdown. Technical success was achieved in all and clinical success in 15 of 16.

Adult↗
PubMed1986

Disposition of aprophen in rats.

The pharmacokinetics of [14C]aprophen and its distribution were determined after intravenous administration to rats. The drug was distributed rapidly with a t1/2 (alpha) of 4 min to highly perfused organs like the brain, kidney and adrenals. An elimination phase was apparent 10 min after injection with a t1/2 (beta) of 23.5 min. The high plasma clearance of the drug was due both to a large volume of distribution and to a high metabolic rate. Aprophen could be hydrolysed to diphenylpropionic acid and diethylaminoethanol in-vivo and in-vitro. Diethylaminoethanol competed with [3H]QNB binding to muscarinic receptors of N4TG1 cells, whereas diphenylpropionic acid did not. The lower plasma concentrations and lower binding activity of diethylaminoethanol compared with aprophen indicate that unchanged aprophen is largely responsible for the in-vivo actions.

Animals↗
PubMed1986

Failure in placement of trocar-mounted catheters.

Some commercially available catheters have a trocar with a small knob at the tip. If the catheter is pushed retrograde on the trocar such that the tip lies behind the knob, it may be impossible to advance it again. To avoid this problem, we suggest dilating the track to two French sizes larger than the catheter, using a larger stylet, or using a more rigid catheter.

Catheterization↗