RESUMEN
BACKGROUND AND STUDY AIMS: The monopolar hot biopsy technique is a widespread method of removing and cauterizing small colonic polyps. Due to the insulated cups of the biopsy forceps, it also allows adequate histological interpretation of the resected specimen. In our experience, polyps removed using the monopolar hot biopsy technique have been less histologically interpretable in comparison with polyps removed using cold biopsy forceps. The aim of this study was to assess and compare the diagnostic quality of polyps obtained using the hot biopsy and cold biopsy techniques. PATIENTS AND METHODS: This was a prospective study of consecutive patients undergoing colonoscopy with removal of polyps using either hot biopsy or cold biopsy techniques. One experienced endoscopist using the same techniques carried out the biopsies. An experienced gastrointestinal pathologist, blinded to the technique used, evaluated the specimens for diameter, artifacts, cautery damage, tissue fragmentation, and general histological and diagnostic quality. Statistical analysis was carried out using the chi-squared test, Fisher's exact test, and Student's t-test. RESULTS: Forty-three consecutive patients (84 % men; mean age 63.8 +/- 15 years) underwent 88 biopsies (45 hot biopsies and 43 cold biopsies). There were no statistically significant differences between the two study groups with regard to demographic data, indications for colonoscopy, endoscopic findings, or polyp size. Cautery damage, architectural distortion, and tissue fragmentation occurred more frequently in polyps resected using the hot biopsy technique ( P < 0.001). CONCLUSIONS: The quality of the specimens removed by cold biopsy was generally better than when using hot biopsy technique. Histological evaluation is more difficult in polyps resected with the hot biopsy technique in comparison with the cold biopsy technique. When the nature of polyps affects the patient's management, a biopsy may be obtained before polyp coagulation.
Asunto(s)
Pólipos del Colon/patología , Pólipos del Colon/cirugía , Criocirugía , Electrocoagulación , Anciano , Biopsia/métodos , Colonoscopía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Reproducibilidad de los ResultadosRESUMEN
Streptozotocin (STZ), an analogue of GlcNAc, inhibits purified rat spleen O-GlcNAc-selective N-acetyl-beta-D-glucosaminidase (O-GlcNAcase), the enzyme that removes O-GlcNAc from protein. We have shown previously that STZ increases pancreatic islet O-linked protein glycosylation. In light of these data, we investigated the possibility further that STZ causes beta-cell death by inhibiting O-GlcNAcase. In isolated islets, the time course and dose curve of STZ-induced O-glycosylation correlated with beta-cell toxicity. STZ inhibition of rat islet O-GlcNAcase activity also paralleled that of its beta-cell toxicity, with significant inhibition occurring at a concentration of 1 mM. In contrast, STZ inhibition of rat brain O-GlcNAcase and beta-TC3 insulinoma cell O-GlcNAcase was significantly right-shifted compared with islets, with STZ only significantly inhibiting activity at a concentration of 5 mM, the same concentration required for beta-TC3 cell toxicity. In comparison, N-methyl-N-nitrosourea, the nitric oxide-donating portion of STZ, did not cause increased islet O-glycosylation, beta-cell toxicity or inhibition of beta-cell O-GlcNAcase. Enhanced STZ sensitivity of islet O-GlcNAcase compared with O-GlcNAcase from other tissues or an insulinoma cell line suggests why actual islet beta-cells are particularly sensitive to STZ. Confirming this idea, STZ-induced islet beta-cell toxicity was completely blocked by GlcNAc, which also prevented STZ-induced O-GlcNAcase inhibition, but was not even partially blocked by glucose, glucosamine or GalNAc. Together, these data demonstrate that STZ's inhibition of beta-cell O-GlcNAcase is the mechanism that accounts for its diabetogenic toxicity.
Asunto(s)
Acetilglucosamina/análogos & derivados , Acetilglucosaminidasa/antagonistas & inhibidores , Diabetes Mellitus Experimental/etiología , Islotes Pancreáticos/efectos de los fármacos , Estreptozocina/toxicidad , Animales , Encéfalo/enzimología , Relación Dosis-Respuesta a Droga , Glicosilación/efectos de los fármacos , Islotes Pancreáticos/enzimología , Ratas , Ratas Sprague-DawleyRESUMEN
A pigmented left atrial paraganglioma was found at autopsy in a 40-year-old black man who died unexpectedly. The cause of death was ascribed to coronary artery disease. The atrial mass was sharply demarcated and polypoid, measured 4 cm in greatest dimension, and had a cut surface that revealed dark red-brown soft tumor tissue. Histopathologically, the neoplasm exhibited a classic organoid clustering of cells (zellballen) with a prominent capillary network. The chief cells contained a brown-black pigment with histochemical characteristics of melanin. We report a case of pigmented cardiac paraganglioma because of its rarity. To our knowledge, no mention has been made of the presence of pigment in previously reported cases of cardiac paragangliomas.