Atilla Ertan

p53 Protein Accumulation Is a Specific Marker of Malignant Potential in Barrett's Metaplasia

Our aim was to determine the sensitivity andspecificity of p53 accumulation as a marker of malignantpotential in Barretts metaplasia (BM). One hundredeighty biopsies from 61 patients with BM were evaluated for p53 accumulation by immunohistochemistry.Of 25 patients with LGD, 9 had p53-positive biopsies,and of these 5 (56%) developed HGD/CA, whereas 16 hadp53-negative biopsies and none (0%) developed HGD/CA after similar follow-up times (P = 0.0108). Asa marker of malignant potential in BM, p53 accumulationhas a sensitivity of 100%, specificity of 93%, and apredictive value of a positive test of 0.56, compared to sensitivity of 100%, specificity of 64%, andpredictive value of a positive test of 0.2 for ahistologic diagnosis of LGD. We conclude that: (1) p53accumulation is more specific and has better predictive value for subsequent development of HGD/CA thanhistologic diagnosis of LGD. (2) Patients with LGD andp53-positive biopsies are more likely to develop HGD/CA;therefore, they should be followed up more closely than those with LGD and p53-negativebiopsies.

Incidence and Survival Trends of Esophageal Carcinoma in the United States: Racial and Gender Differences by Histological Type

Background: The incidence of esophageal adenocarcinoma in White males has been reported to be increasing. The aims of this study were to determine: 1) the incidence trends of esophageal carcinoma in the United States with an emphasis on histologic type, sex, and ethnicity, 2) whether the reported increase in stage IV tumors can be confirmed, and 3) survival trends and factors affecting survival. Methods: Data from the SEER program of the National Cancer Institute with submission dates 1973-98 were used. Data on Hispanics were available for analysis only for the years 1992-98. Statistical analysis was performed utilizing SEER*Stat and SAS statistical software packages. Results: The incidence of adenocarcinoma in White males is still rising (7.8%/year; P < 0.0001); however, the same trend was observed for White females (6.48%/year; P < 0.0001), Hispanic males (3.91%/year; P < 0.02), and Hispanic females (9.4%/ year; P < 0.04). The incidence of squamous cell carcinoma has been steadily declining in White males and females and in Black females since 1973, with the incidence showing a dramatic and significant decline in Black males beginning in 1992 (8.53%/year; P = 0.0009). Stage 4 carcinoma is declining in incidence. Survival of patients with esophageal carcinomas has been improving. In a Cox multivariate model, independent prognostic factors in esophageal carcinoma included tumor stage, tumor type, gender, race, age at diagnosis, and year of diagnosis. Conclusions: 1) The incidence of adenocarcinoma continues to rise in White males and females, but also in Hispanics, while squamous cell carcinoma is declining; 2) the incidence of stage 4 carcinomas has been declining, and 3) survival has been steadily improving, independently of all other risk factors.

Renal Failure and Nephrocalcinosis Associated With Oral Sodium Phosphate Bowel Cleansing: Clinical Patterns and Renal Biopsy Findings

Acute renal failure (ARF) is rarely reported after bowel preparation with sodium phosphate. We report a patient with mild Crohn disease (in remission), without history of renal disease, and with normal baseline renal function, who developed ARF 14 days after bowel preparation for colonoscopy with oral sodium phosphate. A renal biopsy showed multifocal calcium phosphate deposition in the renal tubules against a background of diffuse chronic tubulointerstitial injury. Review of the literature suggested 2 distinct patterns of ARF in the context of sodium phosphate bowel cleansing. One pattern is characterized by ARF, which develops a few hours or days after sodium phosphate administration, as a component of a systemic syndrome associated with severe hyperphosphatemia and hypocalcemia. Correction of these electrolyte abnormalities was frequently associated with rapid recovery of renal function. The cause of ARF in this context was not clear because the favorable outcome negated the need for renal biopsy. In the second pattern, exemplified by the current patient, ARF was identified incidentally. These patients did not have any features of an acute syndrome immediately after sodium phosphate administration and presented much later (usually weeks) with mild, nonspecific symptoms. At the time of presentation, the serum calcium and phosphate levels were normal. The renal biopsies in each of these patients showed nephrocalcinosis as the possible cause of ARF. The renal failure improved at least partially in most of these patients, but persisted in rare cases.

Upper gastrointestinal endoscopy in normal asymptomatic volunteers

In a prospective study, 355 healthy, asymptomatic, male volunteers, 18 to 45 years of age, were screened by esophagogastroduodenoscopy before admission to clinical trials. One hundred thirty-four volunteers (38%) showed abnormal endoscopic findings. Some volunteers had more than one site of involvement or more than one grade of lesion in each anatomic location. In 49 (14%) of these subjects the esophagus was a site of involvement, while in 86 (24%) the stomach was involved, and in 71 (20%) the duodenum was involved. The point prevalences in these asymptomatic subjects were 8.5% for erosive esophagitis, 12% for erosive gastritis, 10% for erosive duodenitis, 2% for gastric ulcer, and 2% for duodenal ulcer.

Galanin binding sites in rat gastric and jejunal smooth muscle membrane preparations

Receptors for galanin in membranes from the rat gastric and jejunal smooth muscle were studied using [125I] radioiodinated synthetic porcine galanin. Specific binding was time and temperature dependent. At 32 degrees C radioligand was degraded in the presence of smooth muscle membranes in a time-dependent manner. At optimal experimental conditions, the equilibrium binding analyses showed the presence of a single population of high affinity binding sites in both the rat stomach and jejunum (Kd value of 2.77 +/- 0.78 nM and 4.93 +/- 1.74 nM for stomach and jejunal smooth muscle membranes, respectively). The concentration of the high affinity binding sites was 58.19 +/- 11.04 and 32.36 +/- 5.68 fmol/mg protein, for gastric and jejunal preparations, respectively. Specific binding was completely inhibited by 10(-6) M of nonradioactive galanin; was 75% blocked by 1 microM of galanin(9-29); it was 10% blocked by 1 microM of galanin(15-29). Galanin(1-15) at a concentration of 1 microM was ineffective for inhibiting [125I]galanin binding. Deletion of four C-terminal amino acid residues from galanin(9-29) to give galanin(9-25) also resulted in almost complete loss of affinity. Radioiodinated galanin and N-terminally deleted fragments had receptor binding potency in the following order: galanin(1-29) greater than galanin(9-29) greater than galanin(15-29). We conclude that the C-terminal part of the galanin chain is important for the rat gastric and jejunal smooth muscle membrane receptor recognition and binding and that N-terminal amino acid sequences are probably not so important, since galanin(1-15) was not active but galanin(9-29) retained most of the receptor binding activity.

Effect of pituitary adenylate cyclase activating polypeptide on rat pancreatic exocrine secretion

A novel neuropeptide, pituitary adenylate cyclase activating polypeptide (PACAP), which has been isolated from ovine hypothalami, shows 68% homology with vasoactive intestinal peptide (VIP). Since VIP stimulates amylase secretion from the pancreas, we investigated the effect of PACAP and VIP on rat pancreatic exocrine secretion after intravenous injections of PACAP-27, PACAP-38, or VIP at doses of 2.5, 5 or 10 nmol/kg. Results showed: 1) Bolus injection of PACAP stimulated pancreatic amylase and protein secretions in a dose-dependent manner; and 2) Stimulation of amylase secretion with 10 nmol/kg of PACAP-27 was greater than that induced with the same dose of VIP or PACAP-38 (p less than 0.05).

UPPER GASTROINTESTINAL LESIONS AFTER POTASSIUM CHLORIDE SUPPLEMENTS: A CONTROLLED CLINICAL TRIAL

The effects of a new microencapsulated potassium chloride formulation on upper gastrointestinal tract mucosa was compared with that of a popular wax-matrix formulation in 48 healthy volunteers. After a week of KCl, subjects were gastroscoped, the endoscopist being blind to the type of preparation taken. Wax-matrix formulations were associated with a higher incidence of upper gastrointestinal lesions. The lesions were not accompanied by epigastric symptoms. Glycopyrrolate, given to some volunteers to decrease gastric emptying, aggravated the effects of potassium chloride.

Pituitary adenylate cyclase-activating polypeptide relaxes rat gastrointestinal smooth muscle

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a new member of the secretin/glucagon peptides family, being most homologous to vasoactive intestinal peptide (VIP). The present study was designed to investigate a possible effect of PACAP on the rat gastrointestinal smooth muscle in vitro. We demonstrated that 1) PACAP reduced basal smooth-muscle contractions in all portions of the gastrointestinal tract, but the effect of VIP was region-specific. The inhibitory effect of PACAP in midcolon was approximately 100 times greater than that of VIP. 2) PACAP significantly inhibited smooth-muscle contractions induced by acetylcholine or carbachol. The inhibitory effect of PACAP was not affected by hexamethonium and was additive to the inhibitory effect of atropine and pirenzepine. 3) PACAP inhibited smooth-muscle contractions induced by substance P, cholecystokinin, and galanin, even after atropine treatment. Although the exact mechanism of the inhibitory action of PACAP remains to be clarified, PACAP appears to exert its effect in the rat at a site other than muscarinic receptors, probably through a direct effect on gastrointestinal smooth muscle in vitro.

Acid suppression therapy may not alter malignant progression in Barrett's metaplasia showing p53 protein accumulation

Abstract OBJECTIVES: Several previous studies have shown that malignant progression in Barrett’s metaplasia (BM) occurs even in patients treated with fundoplication or acid suppression therapy (AST). The aim of this study was to test the hypothesis that AST may not alter malignant progression in BM if key genes involved in DNA repair and cell cycle control, particularly p53, are defective. METHODS: Initial and follow-up biopsies from 21 patients with BM treated with AST and observed for 1–13 yr were entered in the study. All biopsies were graded for dysplasia and evaluated for p53 protein accumulation and oxidative DNA damage by immunohiostochemistry, using antibodies to p53 and to 8-hydroxydeoxyguanosine, respectively. DNA ploidy was determined using image analysis. Statistical analysis was performed using Kaplan-Meier curves, log rank test, and multivariate regression. RESULTS: Patients with p53 positive initial biopsies were more likely to have progression in dysplasia grade (p = 0.022) and DNA ploidy status (p = 0.023) than those with p53 negative biopsies. In eight patients AST resulted in significant reduction in oxidative DNA damage in the five patients with p53-negative initial biopsies, but not the three with p53 positive ones (p = 0.0007). CONCLUSIONS: We conclude that failure of AST to alter malignant progression in BM may be due, at least in part, to defects in DNA repair and cell cycle control resulting from p53 gene mutation, present before AST treatment. Although AST may be effective in preventing further DNA damage, it is unlikely to alter progression in genetically unstable cells.

Effect of PACAP on gastric acid secretion in rats

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a new VIP-like brain-gut peptide. Its effects on the motility and secretory functions of the gastrointestinal system have been shown in previous studies. In this study we investigated the effect of intravenous PACAP on gastric acid secretion in conscious pylorus-ligated rats and in gastric fistula rats. PACAP showed significant inhibitory effects on pentagastrin- and histamine-stimulated gastric acid secretion, but no effect on basal or carbachol-stimulated secretion in pylorus-ligated rats. It did show dose-related inhibitory effects both on basal gastric acid secretion and on secretion stimulated by pentagastrin, histamine, or carbachol in gastric fistula rats. PACAP did not alter serum gastrin levels. Inhibition of prostaglandin synthesis with indomethacin and immunoneutralization of somatostatin with anti-somatostatin serum did not prevent the inhibitory effect of PACAP on gastric acid secretion in pylorus-ligated rats. We conclude that PACAP most likely has a direct effect on parietal cells and that this effect may be mediated, at least partially, by inhibition of the action of histamine on parietal cells.