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Biomedical subjects

R T Bailey

Publications and source records attributed to R T Bailey.

At least 19 recordsLinked to original sources
PubMed1992

Endothelial cell seeding after carotid endarterectomy in a canine model reduces platelet uptake.

Post-endarterectomy platelet deposition may play an important role not only in vessel wall healing, but also in the development of progressive stenosis. Using a canine model, we investigated the effect of endothelial cell seeding on platelet deposition on endarterectomised arteries. Thirteen dogs underwent bilateral carotid intimectomy (5 cm long) and one side was seeded with an average of 2 x 10(6) viable freshly harvested endothelial cells. Blood flow was restored 20 min after seeding. On the contralateral side, a sham-seeding was performed. Deposition of 111indium-labelled autologous platelets was studied with sequential gamma camera images 3-5 h, 1, 2, 3, 4 days and 4 weeks after surgery. Platelet uptake was statistically reduced on the seeded side. Animals were killed at 4 weeks (nine dogs) and 5 weeks (four dogs) after surgery. Seven arteries for each group were found to be occluded. We conclude that endothelial cell seeding on endarterectomised arteries is feasible and reduces platelet uptake. Improvement in the efficiency of seeding and reduction of endothelial cell loss might permit clinical application of this technique.

Animals↗
PubMed1992

Effect of alprazolam (Xanax) on esophageal motility and acid reflux.

Recent studies suggest that psychotropic drugs may help the symptoms associated with spastic esophageal motor disorders. However, the physiologic effects of central nervous system depression (a side effect of such therapy) on esophageal function is not known. Therefore, we studied the effect of alprazolam (Xanax), a popular new benzodiazepine anxiolytic, in 10 healthy volunteers, using a randomized, placebo-controlled design. Stationary esophageal motility, 24-h pH monitoring, and 24-h ambulatory motility monitoring was done while on placebo or one tablet (0.25 mg) of alprazolam taken three times a day. Alprazolam had no significant effect on lower esophageal sphincter pressure or motility in the esophagus. Upper esophageal sphincter pressure, however, was significantly decreased. What is more important, one-third of the healthy volunteers had abnormal amounts of nocturnal acid reflux during the alprazolam phase of the study. This effect was probably due to alprazolam-induced central nervous system depression interfering with normal nocturnal acid clearance mechanisms triggered by arousal from sleep.

Adult↗
PubMed1990

Ten-year results with the St. Jude Medical prosthesis.

Although the hemodynamic characteristics and durability of the St. Jude valve prosthesis have been reported, the need for and the degree of anticoagulation in patients who receive these valves remain uncertain. Our 10-year experience with 165 patients (100 men and 65 women, mean age of 58 +/- 13 years), who underwent valve replacement with St. Jude prostheses, is reported. Of the 165 patients, 147 were treated with warfarin. A prothrombin time 1.3 to 1.8 times control (range 15 to 20 seconds) was maintained in 134 patients with single valve and 1.8 to 2 times control (range 20 to 25 seconds) in 13 patients with double valve prostheses. The 10-year actuarial event-free incidence from thromboembolic and hemorrhagic complications was 84 and 95%, respectively. Of the 8 patients receiving antiplatelet therapy alone, 4 had thromboembolic events. Of the 10 patients on neither warfarin nor antiplatelet therapy, 3 had thromboembolic events. The 10-year actuarial event-free incidence from valve failure was 95%. The 10-year actuarial patient survival was 55%. Thus, the St. Jude valve is a safe and reliable prosthesis with acceptable overall long-term performance in patients given a modest anticoagulation regimen. Patients who receive St. Jude prosthetic valves without anticoagulants have a high incidence of thromboembolic events despite therapy with antiplatelet agents.

Adolescent↗
PubMed1990

Drug-induced esophageal injury. Histopathological study in a rabbit model.

The purpose of this animal study was to investigate the histopathologic consequences of esophageal exposure to a variety of medications known to be injurious to the human esophagus. Twenty-four New Zealand white rabbits were utilized. Tablets or control plastic beads were secured to a silk suture thread and positioned in the rabbit esophagus through a proximal esophagostomy and a gastrostomy. Test medications were allowed to dissolve passively on the surface of the esophageal mucosa in the anesthetized rabbits. After 1 hr of drug exposure, the rabbits were killed and the esophagus removed and examined. No gross abnormalities were detected with the exception of a mild degree of erythema at some of the exposure sites. All medications and control beads produced microscopic mucosal changes when compared to suture controls. The beads and test medications caused thinning of the epithelium and increased subepithelial edema (P less than 0.05). Two changes, however, were unique to animals exposed to test medications: fraying and/or splitting of the epithelium and the presence of balloon cells (P less than 0.05). Balloon cells represent damaged squamous epithelial cells recognizable by their distended, globoid shape. The prevalence of balloon cells ranged from 22% to 89% of sites exposed to drug and was most commonly associated with potassium. Of all drugs reported to cause injury to the human esophagus, potassium chloride has been reported to produce the most severe lesions, including esophageal stricture and perforation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Influence of dissolution rate and pH of oral medications on drug-induced esophageal injury.

The in vitro dissolution time and pH were measured for 16 drug products in capsule or tablet form representative of oral medications known to cause esophageal injury. The test drugs included Vibramycin, Minocin, quinidine sulfate, Cleocin HCl, Indocin, Tolectin 200, ferrous sulfate, vitamin C, aspirin, Procardia, phenobarbital, Dilantin, Butazolidin, Noctec, K-Dur, and Quinaglute. Artificial saliva (10 mL) was placed in a small beaker along with a pH probe connected to a digital display pH meter and a strip-chart recorder. The salivary pH was measured at baseline and continuously during the dissolution of each test medication and the time taken for complete dissolution was recorded. This experiment was repeated six times for each drug. Baseline and final dissolution pH were compared statistically for differences using the Wilcoxon matched-pairs signed-ranks test. Significance was established at the 0.05 level. Only three medications tested (vitamin C, aspirin, and Dilantin) produced a dissolution pH outside the range of physiological esophageal pH values. Although the majority of the test drugs significantly altered the baseline pH, the final dissolution pH did not fall outside the physiologic range. Nine of the 16 test drugs dissolved completely within 10 minutes, whereas the remaining 7 drugs took 30 minutes or longer (up to 24 hours) to dissolve. We conclude that the dissolution pH of potentially caustic medications does not appear to be a primary mechanism of drug-induced esophageal injury, whereas a rapid dissolution rate may play an important role in the pathogenesis of the lesion.

Administration, Oral↗
PubMed1989

Analysis of thirty-two patients with Schatzki's ring.

Schatzki's ring is a distinct anatomical entity associated with hiatal hernia; however, its significance is unclear. Thirty-two patients with a radiologically demonstrated Schatzki's ring were compared with 32 patients with hiatal hernia and no Schatzki's ring. Schatzki's ring was confirmed on endoscopy in 59 percent of patients. Seventy-five percent of patients with Schatzki's ring presented with dysphagia compared with 41 percent of control patients (p less than 0.01). Heartburn and regurgitation were less frequent than in control subjects (38 percent versus 91 percent, p less than 0.0001). Schatzki's ring patients were found to have a lower incidence of proven gastroesophageal reflux on 24-hour pH monitoring. Those with proven reflux were found to have a more efficient lower esophageal sphincter than control patients. Sixty-two percent of Schatzki's ring patients without proven reflux had a history of chronic ingestion of drugs known to be damaging to the esophageal mucosa, whereas only 26 percent of patients with reflux had this history. This was found in 16 percent of controls. Sixty-two percent of Schatzki's ring patients without reflux responded to a single dilatation compared with 37 percent of those with reflux. These findings suggest an etiologic relationship between pill lodgement and Schatzki's ring in patients without reflux and indicate that different therapy should be employed in these patients.

Adult↗
PubMed1989

Drug-induced esophageal injury: a case report of percogesic.

This is the first case report of esophageal injury caused by Percogesic. A 31-year-old healthy white woman presented with dysphagia and retrosternal pain following the ingestion of a Percogesic tablet. The patient felt the tablet lodge in her mid-esophagus even though she ingested it with a cupful of water and in the upright position. Additional fluid was taken to dislodge the tablet with no success. Past medical history was unremarkable for heartburn, regurgitation, or dysphagia. Upper gastrointestinal endoscopy revealed a well-circumscribed deep ulceration in the mid-esophagus. Hospitalization was required due to persistent dysphagia. Treatment consisted of a three-day regimen of liquid antacid, intravenous ranitidine hydrochloride, and metoclopramide. This case emphasizes that pill entrapment can occur in the esophagus in healthy individuals, even when taken in the upright position with plenty of fluid; and mucosal injury can be produced by drugs not generally reported to cause gastrointestinal adverse effects or mucosal injury.

Acetaminophen↗
PubMed1989

Misoprostol: a prostaglandin E1 analog with antisecretory and cytoprotective properties.

Misoprostol, a methylester analog of prostaglandin E1, with antisecretory and cytoprotective properties, has undergone extensive investigation and has received Food and Drug Administration approval for the prevention of nonsteroidal-induced ulceration. The drug represents the first synthetic, orally active prostaglandin evaluated for the treatment of peptic ulcer disease. Clinical studies reveal a trend toward slightly lower healing rates with misoprostol when compared with histamine (H2)-receptor antagonists in the treatment of gastric and duodenal ulcers. In addition, misoprostol was less effective than H2-blockers in reducing ulcer pain, and caused a higher incidence of adverse reactions, particularly diarrhea occurring in up to 13 percent of the patients treated. Several studies have shown misoprostol to be superior to cimetidine and sucralfate in the prevention of alcohol- and drug-induced gastritis. This report summarizes the biopharmaceutics, pharmacokinetics, and clinical efficacy of misoprostol in the treatment of gastric and duodenal ulcers and in the prevention of mucosal injury.

Alprostadil↗
PubMed1989

Natural history of recurrent carotid artery disease.

Controversy exists as to whether early and late recurrent stenosis of the carotid artery represents two distinct types of recurrence or whether it is the same type of lesion detected at different times. Eleven specimens from patients whose carotid arteries were reoperated upon were examined. A temporal sequence was noted: with increasing intervals, the relative presence of areas of myointimal hyperplasia tended to decrease, whereas the relative presence of features of atherosclerosis tended to increase. The clinical data and B-mode ultrasound studies performed from one to 190 months after 210 carotid endarterectomies were reviewed. Twenty-seven carotid arteries (12.9 per cent) exhibited hemodynamically significant restenosis. Three ultrasonographic patterns were described: homogenous soft plaque, homogenous hard plaque and heterogenous plaque. A previous correlation between ultrasonographic and pathologic findings showed the three ultrasound patterns to correlate with myointimal hyperplasia, fibrous atherosclerotic plaque and complex atherosclerotic plaque, respectively. Soft plaques were detected earlier than heterogenous plaques (p less than 0.001). Results from serial studies showed progression of soft plaque to hard or heterogenous plaque, or both. Early and late recurrent lesions are the same type of lesion detected at different intervals. Symptoms of cerebral ischemia are more common at the stage of heterogenous plaque (p = 0.02).

Aged↗
PubMed1987

Reliability of implantable central venous access devices in patients with cancer.

We reviewed complications requiring removal of Hickman catheters (HCs) and implantable central venous access devices (ICVADs) in patients with cancer over a 30-month period. The study was unique in the sense that patients chose which system would be inserted, unless continuous infusion was anticipated. A total of 115 systems were inserted in 102 patients. Forty-four HCs were inserted in 34 patients (total system days, 8533 [mean, 194 days]); 71 ICVADs were inserted in 68 patients (total system days, 18,681 [mean, 263 days]). Complications required removal in 38.6% of HCs and 18.3% of ICVADs. Complication rates were one in 501 days in the HC group and one in 1450 days in the ICVAD group. Although 15 systems were removed for suspected infection, closer analysis revealed that bacteremia ultimately found to be unrelated to the catheter resulted in premature removal in many cases. The catheter tip was located high in the superior vena cava or in the subclavian vein in all systems removed due to thrombosis. Miscellaneous complications in HCs included dislodgment and catheter embolism. The increased longevity, lower complication rate, and decreased maintenance requirements in the use of ICVADs support their superiority over HCs in the treatment of patients with cancer.

Adolescent↗
PubMed1987

Drug-induced esophageal strictures.

A retrospective study of 55 patients with a benign esophageal stricture showed that in 11 patients (20%) the cause was a drug-induced lesion due to potassium chloride (3), tetracyclines (3), aspirin (2), vitamin C (1), phenytoin (1), and quinidine (1). Five of the 11 patients would have been diagnosed as having a reflux etiology of their stricture if 24-hour esophageal pH monitoring was not performed. Six patients responded to dilatation and five patients required resection or bypass. A prospective study of 18 asymptomatic volunteers showed a high incidence of esophageal lodgment of a radiolabeled medicinal capsule, with subsequent dissolution and release of the isotope. This occurred most frequently in elderly subjects and was reduced by increasing the volume of water chaser. The sites of lodgment correspond to the location of the observed strictures in the patient population. An in vitro study showed that, when the causative drugs were mixed with saliva, dissolution occurred within 60 minutes and was associated with significant changes in pH. These investigations show that drug-induced esophageal strictures are more common than previously appreciated, and can be confused with a reflux etiology. Diagnosis is suggested by a history of drug ingestion, location of the stricture, and a normal esophageal acid exposure on 24-hour pH monitoring. The severity of the esophageal injury is variable and requires dilatation to resection for therapy.

Adolescent↗
PubMed1987

Factors influencing the transit of a gelatin capsule in the esophagus.

The tendency of a gelatin capsule to lodge in the esophagus, dissolve, and release its contents, as a potential etiology of drug-induced esophageal injury, was studied in 18 asymptomatic volunteers. Their ages ranged from 21 to 81 years, with nine subjects over 70 years old. Esophageal transit time of liquids was measured in all subjects after which the esophageal transit time of a #00 gelatin capsule containing technetium (99mTc) sulfur colloid was measured with a 120 ml and a 15 ml water bolus. The capsule lodged in three subjects (17 percent) with the 120 ml bolus and in 11 subjects (61 percent) with the 15 ml bolus. Esophageal manometry demonstrated a lower mean amplitude of esophageal contractions in subjects in whom the capsule lodged with the 120 ml bolus and in the elderly subjects. We conclude that the esophageal transit time of a gelatin capsule is related to the volume of fluid chaser. Our findings that a lower amplitude of esophageal contractions was associated with elderly patients and those in whom the capsule lodged with the large fluid bolus are worthy of further investigation.

Adult↗
PubMed1987

A simple technique for constructing a loop enterostomy which allows immediate placement of an ostomy appliance.

A technique for constructing a loop enterostomy using a red Robinson catheter as a stabilizing "rod" is described. The catheter is placed subcutaneously and exits through skin stab wounds placed far enough from the stoma to allow immediate placement of a standard ostomy appliance. By eliminating the skin level rod common to most descriptions of loop enterostomy construction techniques, difficulty with good fixation of skin appliances is eliminated.

Catheterization↗
PubMed1986

An in-vitro morphological study of Q-switched neodymium/YAG laser trabeculotomy.

Laser trabeculotomies produced by directing a pulsed neodymium/YAG laser beam at specimens of human anterior chamber angle obtained post mortem or after enucleation were studied by light microscopy and by scanning and transmission electron microscopy to assess the dimensions of the openings created in the trabecular meshwork, their penetrance to the canal of Schlemm, and the extent or absence of laser induced cellular damage in immediately adjacent tissue. A pulse duration of 40-50 ns at energy levels of around 30 mJ was used and the laser cavity carefully tuned to give a Gaussian spatial mode pattern. Openings in the trabecular meshwork typically of 100 microns in diameter and penetrating through to the canal of Schlemm could be regularly created with only minimal damage to adjacent tissue as judged by transmission electron microscopy. The information so gained may be useful in determining the parameters required for successful laser trabeculotomy as a treatment for primary open-angle glaucoma.

Aged↗
PubMed1986

Heparin-associated thrombocytopenia: a prospective comparison of bovine lung heparin, manufactured by a new process, and porcine intestinal heparin.

Heparin-associated thrombocytopenia has been reported most commonly with bovine lung preparations. We prospectively evaluated the incidence of thrombocytopenia in 43 patients receiving intravenous continuous infusions of either bovine lung heparin, manufactured by a new process, or a standard porcine intestinal mucosa heparin for a minimum of five days in a double-blind, randomized fashion. The decision to continue heparin therapy beyond five days was made by the patient's primary physician. All patients had documented acute thromboembolic disease, pretherapy platelet counts greater than 150 000/mm3, and no evidence of prior coagulation disturbance. No patients had undergone cardiopulmonary bypass or hemodialysis within seven days previous to the initiation of heparin therapy. Thrombocytopenia was defined as a decline in platelet count from the normal range of 150 000-350 000/mm3 to less than 100 000/mm3. Thrombocytopenia occurred in one patient (4.6 percent) receiving bovine lung heparin on day nine of therapy and in no patients (0 percent) receiving porcine intestinal mucosa heparin. Adverse reactions occurred in nine patients (42.9 percent) receiving porcine intestinal heparin and five patients (22.7 percent) receiving bovine lung heparin. This difference was not statistically significant. The results of this study indicate that the incidence of thrombocytopenia is low (less than five percent) with both bovine lung heparin, manufactured by a new process, and porcine intestinal mucosa heparin when therapy is limited to short therapeutic courses (less than 1 week).

Aged↗
PubMed1985

In vitro studies with a pulsed neodymium/YAG laser.

The relationships between the destructive effects of Q-switched Nd/YAG laser pulses and a number of experimental parameters were studied for various target materials including in particular excised, fixed samples of human trabecular meshwork. The laser parameters altered were the pulse energy, the convergence angle of the focused beam, and the position of the focus of the beam relative to the target's axial position. The main finding was that it was possible to make deep holes, of a diameter less than 100 micron, in virtually transparent samples of trabecular meshwork with a laser delivery system of 6 degrees convergence and pulse energies of 14 mJ or more. The relevance of this and the other experimental results to the development of a reliable system for performing internal trabeculotomies for the treatment of open-angle glaucoma is presented.

Cornea↗