Juan Lechago

p53 protein accumulation in Barrett's metaplasia, dysplasia, and carcinoma: A follow-up study

BACKGROUND There is a significant interobserver and intraobserver variation in grading dysplasia in Barretts metaplasia. New markers are needed to optimize the assessment of potential risk of cancer development in these patients. The aim of this study is to explore the use of p53 as a marker of neoplastic progression in Barretts metaplasia. METHODS Immunohistochemistry was used to study p53 protein accumulation in 114 specimens from 54 patients with Barretts metaplasia. RESULTS Positive staining was found in 0% of the cases negative for dysplasia, 9% of those with low-grade dysplasia, 55% of those with high-grade dysplasia, and 87% of those with adenocarcinoma. Follow-up was available on 24 patients. Two patients who showed low-grade dysplasia and who were positive for p53 on biopsy showed high-grade dysplasia in follow-up biopsies. Of 21 patients who had biopsy specimens negative of p53, only one showed high-grade dysplasia on subsequent biopsy specimens. CONCLUSIONS Our data support the hypothesis that p53 plays an important role in the progression of Barretts metaplasia to adenocarcinoma. The follow-up study indicates that positive immunostaining for p53 may be an objective marker of neoplastic progression in Barretts metaplasia.

Diagnosing Primary and Metastatic Renal Cell Carcinoma: The Use of the Monoclonal Antibody `renal Cell Carcinoma Marker'

The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with ≥10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with ≥10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.

A pilot study of adalimumab in infliximab‐allergic patients

The anti-TNF-&agr; antibody infliximab (Remicade) is highly effective in the treatment of Crohns disease. A subset of patients experience allergic reactions as a result of antibodies to infliximab (ATIs). The purpose of the current study is to describe the safety and efficacy of adalimumab (Humira) in patients previously allergic or intolerant to infliximab. Adalimumab is an anti-TNF-&agr; agent containing only human peptide sequences. Seven patients have been treated with adalimumab who had experienced immediate- or delayed-hypersensitivity reactions to infliximab and one with infliximab-induced lupus. Except for injection site discomfort, adalimumab was well tolerated without signs or symptoms of allergic reactions. One patient who had previously received pooled human immunoglobulin developed a pruritic rash after each dose of adalimumab. Patients with active disease who had previously experienced a robust response to infliximab responded to adalimumab as reflected by an improvement in Harvey-Bradshaw index and inflammatory markers. Based on these preliminary data, adalimumab may be a safe and effective substitute for infliximab-allergic patients. Individuals who have been exposed to human antibodies may be sensitized to other human antibodies such as adalimumab.

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.

Depression of Antral and Serum Gastrin Concentration by Food Deprivation in The Rat

In rats fasted 4 days, immunoreactive gastrin concentrations decreased to one-third of the fed levels in antral tissue and to one-eight of the fed levels in serum. The number of antral cells that reacted with fluorescent antigastrin antiserum was also correspondingly decreased. After refeeding, serum gastrin returned to normal levels in 6 days, whereas antral gastrin concentration recovered after 9 days. Normal gastrin levels were maintained in rats fed a nutritious liquid diet over a 6-day period, whereas tissue and serum hormone concentrations decreased to low levels in rats placed on a high bulk non-nutritive diet over the same period. These results suggest that food in the gastrointestinal tract is necessary for the maintenance of normal serum and antral gastrin concentration in rats. The effect of food is most likely attributable to chemical constituents and not distention by bulk.

P16 and Ki67 immunostaining is a useful adjunct in the assessment of biopsies for HPV-associated anal intraepithelial neoplasia

P16 is a tumor suppressor gene product, shown to be overexpressed in most cervical carcinomas and dysplasias associated with high-risk human papilloma virus (HPV) infection. HPV is also associated with anal squamous dysplasias and carcinomas. Significant interobserver and intraobserver variation exists in the interpretation of biopsies for anal intraepithelial neoplasia (AIN). This study was undertaken to assess the potential role of p16 and Ki67 immunohistochemical expression in refining the diagnosis and grading of AIN.One-hundred and four anal biopsies from 74 patients were retrieved from the surgical pathology files of the department. After discrepancies were resolved and concurrence was achieved by at least 2 of 3 reviewing pathologists, the diagnoses were as follows: 37 negative, 12 condylomas without overt dysplasia, 14 AIN I, 25 AIN II, and 16 AIN III. p16 and Ki67 expression was evaluated by ABC immunoperoxidase staining whereas the presence of the high-risk subtypes of HPV virus was determined by in situ hybridization on a subset of the biopsies. Results were reviewed by 2 pathologists and positive and negative staining was correlated with H&E diagnoses. Nuclear and/or nuclear and cytoplasmic staining was considered as positive for p16 when present in >10% of squamous cells. Two patterns of positive p16 staining were observed: (1) “spotty” in which positive cells were scattered throughout the lesion and (2) “band” in which >90% of contiguous cells in the lesion stained positive. A band-like pattern of p16 immunoreactivity was seen in 21.4% AIN I, 80% AIN II, and 87.5% AIN III cases. None of the condylomas and only 1 of the negative cases showed a band of p16 positive staining. Spotty p16 immunoreactivity was observed in 8.1% negative, 8.3% condyloma, 14.3% AIN I, 12.0% AIN II, and 12.5% AIN III cases. More than 50% of nuclei stained positive for Ki67 in 28.6% AIN I, 48.0% AIN II, and 75.0% AIN III cases but in none of the negative or condyloma cases. On the basis of these results, a band-like pattern of p16 staining and Ki67 positivity in >50% of the squamous cell nuclei were strongly associated with high-grade AIN. Conversely, absence of a p16 band of positivity coupled with Ki67 positivity in <50% of nuclei was frequently associated with benign lesions. Band like p16 staining also correlated strongly with the presence of high-risk HPV. Most AIN I lesions stained similar to the nondysplastic cases. A small subset of biopsies studied did not conform to the pattern described above: 4 of 14 (28.6%) AIN I lesions showed a band-like pattern of p16 staining and/or >50% Ki67 positive nuclei. Two of these cases were positive for high-risk HPV DNA. 4 of 25 (16.0%) AIN II lesions comprising 9.8% of the 41 high-grade AINs (AIN II and III) showed spotty p16 positivity and <50% Ki67 positive nuclei. One was positive for high-risk HPV DNA. We conclude that when used together and evaluated in conjunction with H&E stained sections, p16 and Ki67 immunoexpression is a useful adjunct in the diagnosis and grading of AIN.

Antral G-cell and D-cell numbers in Helicobacter pylori infection: Effect of H. pylori eradication

BACKGROUND It has recently been recognized that Helicobacter pylori infection is associated with abnormalities in the regulation of gastrin secretion. We investigated whether there was a relationship between H. pylori infection and G-cell and D-cell numbers. METHODS The numbers of antral G cells and D cells were compared between 20 patients with duodenal ulcer and 24 volunteers, 12 with and 12 without H. pylori infection. The effect of eradication of H. pylori infection on G-cell number was also evaluated. Antral mucosal biopsy specimens were examined using immunohistochemical techniques specific for the presence of gastrin and somatostatin. RESULTS The number of G cells was significantly (P < 0.02) less in patients with duodenal ulcer than in either infected or uninfected controls (3.7 +/- 0.3 vs. 6.2 +/- 0.6 and 5.3 +/- 0.5 G cells per gland for infected and uninfected controls, respectively). The ratio of G-cells to D-cells was similar in duodenal ulcer patients (2.2) and uninfected controls (2.0). It was found that, although eradication of the H. pylori infection results in a dramatic reduction in stimulated gastrin secretion, it is not associated with a change in the numbers of antral G cells or D cells in patients with duodenal ulcer. CONCLUSIONS It is concluded that H. pylori infection-associated increase in gastrin secretion appear to be related to local factors regulating G-cell function.

Role of luminal ammonia in the development of gastropathy and hypergastrinemia in the rat

BACKGROUND/AIMS Chronic infection with Helicobacter pylori causes persistent elevations in gastric juice ammonia levels. Thus, we studied the effects of experimentally induced increases in gastric juice ammonia levels on gastric structure and function and gastrin homeostasis. METHODS Rats were fed either normal chow or the diet supplemented (20 g/dL) with ammonium or sodium acetate. RESULTS Long-term dietary ammonium loading for 2 weeks or longer resulted in a 1.5-2-fold increase in the weight and mucosal thickness of the stomach and proximal duodenum with evidence of mild gastritis and enterochromaffinlike cell hyperplasia. The ammonium-containing diet also induced a significant 2-3-fold increase in both circulating gastrin levels of fed rats and an increase in the postprandial gastrin responses over control values. Antral gastrin levels were also markedly elevated by long-term ingestion of the test diet, which was increased 3-4-fold over control values in fasted animals and less so after meal stimulation. Consistent with these findings, gastrin-specific messenger RNA was increased 2.5-3-fold in the antrum of ammonium fed rats, whereas actin-specific messenger RNA was not affected or decreased. Animals fed a diet supplemented with 20 g/dL sodium acetate sustained modest increases in mucosal thickness and serum and antral gastrin concentration, suggesting that nonspecific gastric injury and inflammation is also a factor that influences G-cell function. CONCLUSIONS Long-term exposure of the antral mucosa to elevated levels of ammonia in the gastric juice in the presence of gastritis, conditions similar to that occurring in subjects infected with H. pylori, seem to be causative factors in the development of G-cell hyperfunction.

Bile duct carcinoma associated with multiple von meyenburg complexes in the liver

A 61-year-old white woman was found to have disseminated abdominal carcinoma at autopsy. The primary site proved to be a bile duct carcinoma arising from ductal epithelium of multiple von Meyenburg complexes of the liver. No other neoplastic lesion was found elsewhere after careful, gross, microscopic examination. This case is thought to represent malignant transformation of the hamartomatous growth, previously reported only exceptionally.

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.