Endoscopic submucosal dissection: a safe technique for colorectal tumors.

BACKGROUND AND STUDY AIMS: Endoscopic submucosal dissection (ESD) aims to resect large neoplastic lesions en bloc, allowing for more precise histopathological analysis. The present retrospective study aimed to analyze the technical and clinical outcomes after ESD of colorectal tumors. PATIENTS AND METHODS: ESD was performed for the treatment of 71 colorectal neoplasms in 70 patients (38 men, 32 women; mean age 63.4 years). Lesion size, procedure time, complications, and immediate and follow-up outcomes were evaluated. The results for these 71 lesions were compared with those for a group of 32 lesions treated by conventional piecemeal endoscopic mucosal resection (EMR) performed during the same period. RESULTS: For the ESD-treated group of lesions, the average lesion size was 32.7 mm (range 13-80 mm), and the mean operating time was 61.1 minutes (range 7-164 minutes). One perforation occurred in the ESD group (1.4%) and this was treated conservatively with clipping. The majority of these lesions (n = 50) were laterally spreading tumors. Histological examination showed low-grade adenoma in 12 cases; high-grade intraepithelial neoplasia in 47 cases; and submucosally invasive cancer in 11 cases, of which four were sm1, and seven were sm2 or sm3 (these seven patients underwent surgery). The en bloc resection rate was 98.6%. For the 64 tumors that were treated by radical endoscopic resection, no tumor recurrence was found after a mean follow-up period of 12.2 months (range 3-34 months) and a mean of 2.1 follow-up endoscopies (range 1-4). This contrasted with the 6.3% recurrence rate in the 32 piecemeal EMR cases (mean tumor size 28.7 mm, range 20-60 mm). CONCLUSION: In our hands, ESD is a safe and effective resection technique for large colorectal neoplasms. As experience with the technique increases, it might gradually replace piecemeal EMR in the majority of cases.

Endoscopic mucosal resection of the colon: the Japanese technique.

Early colorectal neoplasms, especially flat-type and depressed-type lesions, should be treated with an EMR technique. In general because depressed-type lesions, in contrast to flat-type or protruded-type lesions, tend to invade the submucosa rapidly, they ought to be treated by EMR at an early stage. Histopathologically in the case of lesions that only minimally invade the submucosa without vessel invasion (sm1a and sm1b without vessel invasion), a treatment can be completed with EMR. Massive submucosal invasive cancers ought to be resected by surgical treatment because of the risk of recurrence or metastasis. In addition, pit pattern diagnosis with magnifying colonoscopy is useful to determine a therapeutic method for colonic neoplasms. Lesions with the type VN pit pattern represent malignancy and usually invade the submucosa massively, so it is better to treat them surgically from the outset. Endoscopic mucosal resection should be conducted under fully controlled endoscopy to prevent complications. EMR is a superior therapeutic method and will be performed frequently in the future. It is necessary for colonoscopists to determine a suitable therapy for each colorectal neoplastic lesion. They also need to master the EMR technique in the correct manner.

Colonoscopic diagnosis and management of nonpolypoid early colorectal cancer.

Nonpolypoid colorectal neoplasms are grossly classified into three groups: slightly elevated (small flat adenomas), laterally spreading, and depressed. Flat adenomas are not invasive until they are rather large, whereas depressed lesions can invade the submucosa even when they are extremely small. Nonpolypoid lesions are difficult to detect and are often overlooked. Keys to detect them are their slight color change, interruption of the capillary network pattern, slight deformation of the colonic wall, spontaneously bleeding spots, shape change of the lesion with insufflation and deflation of air, and interruption of the innominate grooves. Spraying of indigo carmine dye helps to clarify the lesions. A pit pattern analysis with a zoom colonoscope is useful for the diagnosis and staging of early colorectal cancer. Small flat adenomas are thought to be precursors of protruded polyps and lateral spreading tumors, whereas depressed lesions are thought to grow endophytically and become advanced cancers. Small depressed lesions are treated with an endoscopic mucosal resection (EMR) technique; but when they massively invade the submucosa, surgical resection is indicated. Laterally spreading tumors are not as invasive despite their large size and therefore are good indications for the EMR or piecemeal EMR method. Small flat adenomas need not be treated urgently, as almost none is invasive. Accurate diagnosis with dye-spraying and zoom colonoscopy is vital for deciding the treatment strategy.

Molecular conformation of porcine amelogenin in solution: three folding units at the N-terminal, central, and C-terminal regions.

Circular dichroism (CD) studies were conducted to gain a better insight into the conformation of amelogenins, which were isolated from developing enamel of piglets. The intact porcine amelogenin and its degraded products were purified chromatographically. The 25-residue peptide corresponding to the segment at the C-terminus was synthesized. CD spectra of these samples were measured at pH 5.0-5.3 in the temperature range between 4 and 90 degrees C. The most remarkable finding was that the CD spectrum of the intact amelogenin was accounted for by the sum of the spectra of the three fragments at the N-terminal, central, and C-terminal regions, supporting the hypothesis that the structure of the whole protein consists of discrete folding units. Furthermore, low-angle laser light scattering analysis provided evidence that the 20 kDa amelogenin, the most abundant extracellular matrix protein in forming enamel tissue, exists in a monomeric form at pH 5.3 and 25 degrees C. It was tentatively concluded that the N-terminal region contains beta-sheet structures, while the spectral characteristics of the C-terminal region are similar to those of a random coil conformation. The conformation of the central region was characterized by a strong negative ellipticity at 203 nm, although its nature remains to be defined.