Glutathione S-transferase: a potential new marker of intestinal ischemia.

BACKGROUND/PURPOSE: The accurate and early diagnosis of intestinal ischemia remains difficult chiefly because of a lack of a suitable marker that is noninvasive and easy to use. The glutathione S-transferases (GST) are a family of cytosolic enzymes involved in detoxification and released from a variety of cells when the cell membrane is damaged. The enzymes are distributed widely in the intestine and show isoform specificity in their distribution throughout the intestinal tract. Several previous reports have shown the utility of these enzymes in the diagnosis of liver and renal graft damage during and after organ transplantation. The object of this study was to determine if GST levels correlated with histologic changes of intestinal ischemia in a controlled animal model of mesenteric intestinal ischemia. METHODS: Control and experimental male Sprague-Dawley rats underwent laparotomy and ligation of the Superior Mesenteric Artery (SMA) and both control and experimental animals were studied at 30, 60, 90, 120, and 240 minutes. Blood taken from the Inferior Vena Cava (IVC) and Portal Vein (PV) and jejunal and ileal perfusates were assayed for alpha and mu isoforms of GST using a commercially available enzyme immunoassay. In addition, jejunal and ileal segments were sampled and reviewed by a histopathologist blinded to the group being studied. RESULTS: A reproducible pattern of intestinal ischemia was noted with worsening grades of injury observed with greater ligation times. Luminal alpha and mu GST release (as measured by the appearance in luminal perfusate) increased with increasing ischemia times. Increased ischemia times resulted in increased levels of alpha and mu GST in both portal and systemic venous samples but lagged behind the appearance of raised luminal GST values. CONCLUSIONS: The results suggest that GST may be an interesting and useful marker in the early detection of intestinal ischemia. Its detection in peripheral blood has implications for a more detailed study design to determine the sensitivity and specificity of this marker in more diverse clinical conditions such as necrotizing enterocolitis and superior mesenteric artery occlusion.

Gastric metaplasia and duodenal ulcer disease in children infected by Helicobacter pylori.

BACKGROUND: Helicobacter pylori infection of the gastric mucosa is vital in the pathogenesis of duodenal ulcer disease. H pylori will only colonise gastric epithelium and its association with duodenal disease is therefore not easily explained. AIMS: To determine if gastric metaplasia in the duodenum increases the risk of duodenal ulcer disease in children infected with H pylori. PATIENTS: All children undergoing upper endoscopy over a 20 month period in a children's hospital in Ireland. METHODS: Two biopsy specimens were obtained from the antral mucosa and two from the first part of the duodenum. One antral biopsy specimen was used in a rapid urease test (Clo Test). Biopsy sections were stained with haematoxylin and eosin and also with cresyl violet for identification of H pylori. Periodic acid Schiff (PAS) stain was performed to identify areas of gastric metaplasia. RESULTS: Gastric and duodenal biopsy specimens were obtained from 148 patients (M:F 1:2:1). Twenty five children (17%) had H pylori positive gastritis. Thirty four children (23%) had gastric metaplasia in the duodenum. Nine per cent of children under the age of 8 years had gastric metaplasia compared with 38% in those 12 years of age or over (p < 0.005). Seven children had duodenal ulcer disease. Gastric metaplasia was present in six of seven (86%) children with duodenal ulcer disease compared with 28 of 141 (20%) without ulceration (p < 0.001). While both H pylori and gastric metaplasia were each significant risk factors for duodenal ulcer disease, the combined presence of both factors was associated with a pronounced increase in duodenal ulcer disease. Duodenal ulcer disease occurred in over 50% of children with both H pylori infection and gastric metaplasia. In contrast duodenal disease did not occur in children (0 of 100) when both were absent. CONCLUSION: The presence of gastric metaplasia in the duodenum is the major risk factor for duodenal ulcer disease in patients colonised by H pylori.

Association of symptoms with Helicobacter pylori infection in children.

The aim of this study was to determine prospectively whether Helicobacter pylori-associated gastritis is associated with specific symptoms by evaluating whether these symptoms are relieved by treatment of the infection. Symptoms resolved after the eradication of H. pylori in only three of eight children with H. pylori-associated gastritis alone, in comparison with all six children with duodenal ulcer disease.

Evaluation of Ki-67 reactivity in neuroblastoma using paraffin embedded tissue.

AIMS: To examine the pattern of reactivity of Ki-67 in neuroblastoma and correlate this with a) clinical prognostic criteria and b) cell cycle statistics (using flow cytometry). METHODS: Four micron sections of paraffin embedded (PE) tissue from 55 patients (25 pre chemotherapy and 30 post) were placed on to aminosialinised slides, dewaxed and rehydrated. Slides were pretreated in a microwave oven, endogenous peroxidase activity blocked using 3% hydrogen peroxide and Ki-67 reactivity investigated using a streptavidin/biotin/peroxidase technique. DNA ploidy was also performed from an immediately adjacent section on the same block using a FACScan and Cellfit software. RESULTS: Ki-67 reactivity was well defined and highly reproducible. Eighteen out of 30 post chemotherapy samples were totally negative, despite evidence of proliferation on flow cytometry and all subsequently died of disease. As interpretation post chemotherapy was therefore deemed unreliable, this group was excluded from analysis. Reactivity in pretreatment samples ranged from 0% to 67%; staining was restricted to the nucleus with a distinct pattern noted in the nucleolus. Ki-67 positivity was lower in aneuploid compared with diploid tumours (mean 26% vs 36%, NS). Among diploid tumours, a lower percentage positivity was noted in those patients with better clinical prognostic parameters. Correlation however between Ki-67 and SG2M phases of cell cycle was poor (RS = 0.39, NS). CONCLUSION: Assessment of proliferation in neuroblastoma by Ki-67 reactivity in paraffin embedded tissue is reliable in pretreatment samples and can be incorporated into routine immunohistochemical evaluation. Larger multicentre studies are required to further evaluate Ki-67 reactivity as a prognostic indicator.

Reactivity of P-glycoprotein monoclonal antibodies in childhood cancers.

P-Glycoprotein (P-gp), the product of the mdr-1 gene, is implicated in the development of chemoresistance in a variety of, mostly adult, cancers. Its role in paediatric tumours, most of which are non-epithelial in origin, has yet to be fully elucidated. A study was undertaken to investigate reactivity of two P-gp monoclonal antibodies (MAbs), JBS-1 and MRK16, recognising cytoplasmic and surface epitopes, respectively, of the P-gp molecule, in a variety of newly diagnosed and relapsed childhood cancers. P-gp was not expressed in any of 36 tumours examined (neuroblastoma 13, nephroblastoma 12, rhabdomyosarcoma 6, lymphoma 3, teratoma 1, Ewings 1), 14 of whom had chemoresistant disease. Reactivity to both MAbs was also investigated in patients with acute leukaemia. Out of 10 diagnostic acute lymphoblastic leukaemia (ALL) samples, a positive reaction with JSB-1 was observed in 1 patient who failed to remit on standard induction therapy and in 3 of 6 patients in ALL relapse, only 1 of whom showed low grade positivity with MRK16. Both MAbs reacted positively in 1 patient with acute non-lymphocytic leukaemia (ANLL) at diagnosis who achieved remission with teniposide and cytosine arabinoside, but relapsed 7 months later and was again positive with both Mabs. JSB-1 also showed varying degrees of positivity in 4 out of 4 other patients in ANLL relapse. It would therefore appear that P-gp is unlikely to mediate chemoresistance in most solid tumours of childhood, but may well play a major role in the development of chemoresistance in acute leukaemia.