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Biomedical subjects

W Silen

Publications and source records attributed to W Silen.

At least 91 records · Page 5Linked to original sources
PubMed1985

Characteristics of sudden potential drop in bullfrog gastric mucosa.

An unusual sudden potential drop (SPD) has been described by Kidder in bullfrog gastric mucosa exposed to anoxia and a serosal pH less than or equal to 7.1. We found that anoxia was not a prerequisite, since under fully oxygenated conditions the SPD occurred reliably in metiamide-treated tissues when the pH of the nutrient solution (pHN) was below 7.1. The SPD was observed also in metiamide-treated tissues exposed to 20 mM luminal or nutrient acetylsalicylic acid (ASA) with pHN = 7.3, an effect that was abolished by increased nutrient HCO3- concentration. The SPD occurred when NO3- but not isethionate or acetate replaced Cl- in the bathing media. A marked increase in potential difference in response to changing luminal Cl- concentration was observed after the SPD, uptake of Cl- from the luminal solution into the tissue increased, but transmural fluxes of Cl- decreased bidirectionally. Permeability to H+ was unaltered in the post-SPD state. An SPD never occurred in antrum under conditions causing SPD in fundus, suggesting that oxyntic cells are prerequisite. We conclude that, under conditions which cause tissue or cellular acidosis and cessation of H+ secretion, fundic mucosae respond with an anion-selective increase in apical permeability manifest as the SPD.

Animals↗
PubMed1985

Differentiation between Crohn's disease and other inflammatory conditions by electron microscopy.

The authors previously have demonstrated axonal necrosis of autonomic nerves in the surgically resected ilea of patients with Crohn's disease both in grossly normal ileal resection margins and in diseased areas. The present study of ileal stomal biopsies was carried out to obviate the possibility that the observed axonal damage might be related to the prolonged surgical manipulations required for ileal resection. The authors present studies of biopsies of ileal stomas and of small bowel from patients with Crohn's disease and various control disorders, including ulcerative colitis. Stomal biopsies were fixed immediately after they were obtained. Widespread, severe axonal necrosis of autonomic nerves was present in all Crohn's disease specimens, regardless of the patient's clinical status or the gross or routine microscopic evaluation of the same specimen. Controls either had no necrosis or displayed a minor degree of focal necrosis involving single axons. The authors conclude that Crohn's disease is accompanied by a severe and extensive necrosis of gut axons, and that such electron microscopic findings may serve to differentiate Crohn's disease from other inflammatory disorders.

Adult↗
PubMed1984

15 (R)-15-methyl prostaglandin E2 does not prevent gastrointestinal bleeding in seriously ill patients.

A prospective, randomized trial was designed to compare the relative efficacy of 15 (R)-15-methyl prostaglandin E2 with antacid (usually Mylanta II) in 46 patients admitted to a respiratory-surgical intensive care unit. Bleeding was assessed by a modification of the Hemoccult slide test. Three of 22 patients in the antacid group bled, and 12 of 24 patients in the prostaglandin group bled, for a highly significant difference (p = 0.008). Patients in whom prophylaxis failed tended to have a greater number of risk factors. Other prostaglandin analogues that do not require conversion from an inactive to an active form, may be more useful than the agent we studied. Based on currently available data, the hourly titration of the gastric juice to a pH of greater than 3.5 remains the preferred method of prophylaxis for acute bleeding from the stomach in seriously ill patients.

Aged↗
PubMed1984

Rapid repair of injured gastric mucosa.

The morphology of the rat gastric mucosa superficially damaged by a 30-45 sec exposure to 100% ethanol caused over 99% of the luminal surface to be necrotic without extensive hemorrhage or hyperemia. However, this damaged area restituted or rapidly healed and the process was described. These findings were compared with in vitro gastric mucosae of bullfrogs and guinea pigs which were damaged with 1 or 1.25 M NaCl and allowed to restitute. The rat gastric mucosa showed evidence of cell migration within 5 min after ethanol damage and after 15 min as much as 50% of the denuded basement membrane was restituted. After 30 min about 75% of the mucosa was covered with cells and by 1 h there were only minor epithelial discontinuities. The in vitro frog mucosal restitution after hypertonic injury was slower and required 1-2 h to show appreciable cell migration and 4-6 h for completion of the repair process. Using chambered guinea pig gastric mucosa damaged with hypertonic NaCl restituted the necrotic surface almost as rapidly as the intact rat stomach necrotized with absolute ethanol. Since prostaglandin treatment did not prevent ethanol or hypertonic salt injury or affect the restitution process it was proposed that the term cytoprotection as it is generally used is not appropriate.

Animals↗
PubMed1984

Pathogenesis, diagnosis and treatment of acute gastric mucosal lesions.

Stress ulcers are multiple superficial mucosal lesions which occur mainly in the fundus of stomachs of seriously ill patients and should be differentiated from reactivation of a pre-existent ulcer diathesis, Cushing's ulcer following head injury, or drug-induced gastritis. It is generally agreed that luminal acid and pepsin are required for ulceration to develop. Experimental evidence suggests that backdiffusion of acid is closely related to the formation of ulcers. In the absence of overt disruption of the gastric mucosal barrier, ischaemia appears to compromise the ability of the gastric mucosa to dispose of backdiffusing acid, which then results in a decrease in intramural pH and ulceration. Reflux of duodenal contents and diffusion of urea from the blood may contribute to the formation of ulcers. Although endoscopic studies have demonstrated gross mucosal injury within hours of the stressful event in nearly 100 per cent of patients examined, most stress ulcers heal when normal gastric defence mechanisms are restored. However, in a small percentage of patients, stress ulceration may lead to frank gastrointestinal haemorrhage requiring medical and/or surgical intervention. Endoscopic findings in conjunction with the history usually differentiates stress ulcer from other bleeding lesions. Angiography may be used if endoscopy fails to identify the bleeding site. Most episodes of bleeding from stress ulceration resolve on medical management consisting of saline lavage, antacids, and adequate supportive measures. Pharmacoangiography with selective infusion of vasopressin or embolization may be of benefit in selected patients with continued bleeding. Surgery is a last resort and has a predictably high mortality. The operation of choice is controversial, but vagotomy, pyloroplasty and oversewing the ulcers may be a good initial operation. Continued bleeding subsequent to vagotomy and pyloroplasty would require near total gastrectomy. Since results of surgical therapy in established stress ulcer disease are poor, the prevention of bleeding is the most rational approach to the management of this disease. The key to prophylaxis is the maintenance of normal intragastric pH. Antacids appear to be superior to cimetidine in preventing bleeding from stress ulcers, so long as the gastric content is buffered to a pH of 3.5 or greater. In seriously ill patients found in respiratory-surgical intensive care units, hourly titration with antacids is the standard against which other forms of prophylaxis must be rigidly compared.

Antacids↗
PubMed1983

Recurrent cholangitis after biliary surgery.

After a biliary-enteric anastomosis, the development of cholangitis is usually assumed to be due to obstruction of the stoma. Six patients in whom this was not the case are described. Achlorhydria, duodenal diverticula, and foreign bodies are important predisposing factors. When bacterial contamination is severe in an abnormal intrahepatic biliary tree, especially that which follows long-standing intermittent common duct obstruction, symptomatic biliary infection may occur in the absence of extra-hepatic biliary obstruction.

Aged↗
PubMed1983

Axillary sampling in the definitive treatment of breast cancer by radiation therapy and lumpectomy.

Between January, 1967 and July, 1980, 176 women who were referred to the Joint Center for Radiation Therapy (JCRT) for definitive breast irradiation underwent low axillary dissection. A typical operative technique is described. The dissection stops short of the axillary vein although the vein is usually visualized. One hundred thirty-two axillae were thought to be N0 or N1a. Forty-six axillae were felt to be N1b. Seventeen percent of the T1 N0 patients had pathologically positive nodes. Twenty-seven percent of the T2 N0 patients had positive nodes. When 5 or less nodes were removed at axillary sampling the incidence of nodal involvement was very low. There were no differences in nodal positivity when comparing upper quadrant to lower or central lesions. Lateral lesions appeared to have higher positivity rates compared with either medial or central lesions. Ninety-four percent of axillae with N1b lesions were pathologically confirmed. The complication rate for this procedure was low. There were 5 transient non-surgical complications and 1 cellulitis resulting in a frozen shoulder, which required corrective surgery. There were no cases of moderate or severe arm edema. Axillary sampling is compared to axillary dissection as a diagnostic procedure. Axillary sampling may underestimate the true pathologic positive rate, but diagnostic accuracy appears excellent if level 1 and 2 nodes are sampled.

Axilla↗
PubMed1983

Significance of post-cholecystectomy subhepatic fluid collections.

A prospective ultrasound study of the right upper quadrant in 105 patients who had undergone cholecystectomy showed the incidence of fluid collection in the gall bladder fossa to be 24% 2 to 4 days after operation. In all but two patients, these fluid collections were of no clinical significance. The relationship between the presence of fluid and several other variables, such as use of drains and surgical techniques, are discussed.

Ascites↗
PubMed1983

Effect of luminal pH and nutrient bicarbonate concentration on restitution after gastric surface cell injury.

Frog fundic mucosas whose surface layers were severely injured by exposure to 1 M NaCl for 10 minutes in an Ussing chamber uniformly recovered both physiologically and anatomically within 4 to 6 hours. The purpose of the present study was to examine the effects of luminal H+ and nutrient HCO-3 concentrations on this process of reconstitution. With 18 mM HCO-3, return of the transmucosal potential difference, tissue electrical resistance, and short-circuit current toward normal and anatomic recovery occurred at luminal pH of 7.4, 5.0, and 4.0 but not at 3.0. An inhibitor of pepsin did not favorably affect the outcome of luminal pH 3.0, but a nutrient HCO-3 concentration of 47.8 mM completely prevented the adverse effects of luminal pH 3.0. Reconstitution of epithelial integrity did not occur in the absence of HCO-3 at luminal pH 4.0. Thus, low luminal pH inhibits and high nutrient HCO-3 concentration supports the epithelial restitution after mucosal damage caused by hyperosmolar NaCl.

Animals↗
PubMed1982

Effect of hyperparathyroidism and hypercalcemia on lower esophageal sphincter pressure.

Heartburn is a frequent and sometimes initial complaint in hyperparathyroidism, and it is often relieved by successful parathyroid surgery. Four of five patients with primary hyperparathyroidism and heartburn obtained relief of symptoms and had an increase in lower esophageal sphincter pressure after successful operative treatment. Four of five volunteers undergoing calcium infusion exhibited a decrease in lower esophageal sphincter pressure after about 2.5 to 3 hours of infusion. Calcium infusion in a treated patient who had an increase in lower esophageal sphincter pressure postoperatively resulted in a transient return of lower esophageal sphincter pressure to preoperative levels.

Calcium↗
PubMed1982

Lessons of parathyroid reoperations.

The case histories of the 23 patients in this series demonstrate the importance of a systematic approach to parathyroid surgery. Ligation of the superior thyroid vessels and mobilization of the upper pole of the thyroid are often necessary to find the superior parathyroid glands that are located on the posterior surface of the thyroid. Devascularization of the thyroid gland does not occur with this maneuver because of abundant collateral circulation from the inferior thyroid artery and tracheal vessels. Normal appearing parathyroid glands should not be resected because this procedure does not treat hypercalcemia and may leave the patient with insufficient parathyroid tissue if an adenoma is found at a later date. Bilateral cervical exploration [35,36] is performed before resection of any abnormal appearing parathyroid tissue. Patients may also have supernumerary parathyroid glands [16], especially in the inferior cervical and superior mediastinal areas that are associated with the thymus [37,38].

Adenoma↗
PubMed1982

Mechanism of luminal alkalinization by bullfrog fundic mucosa.

Metiamide-inhibited fundic mucosa of bullfrog secreted alkali (OH-) at 0.1-0.2 mueq.cm-2.h-1.OH- was abolished by dinitrophenol (DNP) and was decreased significantly by 4,4-didsothiocyano-2,2-disulfonate stilbene (DIDS), anoxia, or HCO3(-)-free nutrient solution. In Na+ solutions, increasing nutrient, [HCO3(-)] augmented OH- and Isc linearly while resistance (R) decreased. No such changes occurred in Na+-free nutrient solution. In all experiments, delta Isc was approximately 12 X delta OH. Replacement of Cl- in the secretory solutions or in the nutrient solutions had no significant influence on OH-. When Na+-free nutrient solutions and Cl--free secretory solutions were present, OH- decreased significantly (P less than 0.01). Increasing nutrient [Cl-] in the absence of secretory Cl- significantly (P less than 0.01) augmented OH- and Isc. In the absence of secretory Cl-, OH- and Isc were linearly related to varying nutrient [Cl-]. In tissues with nutrient solutions on the secretory side and vice versa, apparent OH- was 0.4-0.5 mueq.cm-1.h-1 and was dependent on secretory [HCO3(-)] but was not affected by DNP, DIDS, or replacement of Cl- on secretory or nutrient solutions. We conclude that 1) OH- secretion is dependent on nutrient HCO3(-) and Na+ and oxidative metabolism, 2) endogenous HCO3(-) does not contribute significantly, and 3) adequate tissue Cl- must be present for normal OH-.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗