Lymphatic Drainage of the Splenic Flexure Defined by Intraoperative Scintigraphic Mapping.

BACKGROUND: The optimal surgical management of splenic flexure cancer is debated, partly because of an incomplete understanding of the lymphatic drainage of this region. OBJECTIVE: This study aimed to evaluate the normal lymphatic drainage of the human splenic flexure using laparoscopic scintigraphic mapping. DESIGN: This was a clinical trial. SETTINGS: The study was conducted at a single tertiary care center. PATIENTS: Thirty consecutive patients undergoing elective colorectal resections without splenic flexure pathology were recruited. INTERVENTION: Technetium-99m was injected subserosally at the splenic flexure. MAIN OUTCOME MEASURES: Lymphatic scintigraphic mapping was undertaken at 15, 30, and 60 minutes using a laparoscopic gamma probe at the left branch of the middle colic, left colic, inferior mesenteric, and ileocolic (control) lymphovascular pedicles. RESULTS: Lymphatic drainage at 60 minutes was strongly dominant in the direction of the left colic pedicle (96% of patients), with a median gamma count of 284 (interquartile range, 113-413), versus the left branch of the middle colic count of 31 (interquartile range, 15-49; p < 0.0001). This equated to a median 9.2-times greater flow to the left colic versus the middle colic. Counts at the left colic were greater than all of the other mapped sites at 15, 30, and 60 minutes (p < 0.001), whereas middle colic and inferior mesenteric artery counts were equivalent. The protocol increased operative duration by 20 to 30 minutes without complications. LIMITATIONS: These results report lymphatic drainage from patients with normal splenic flexures, and caution is necessary when extrapolating to patients with splenic flexure cancers. CONCLUSIONS: The lymphatic drainage of the normal splenic flexure is preferentially directed toward the left colic in the high majority of cases. Retrieving these nodes should be prioritized in splenic flexure cancer resections, with important secondary emphasis on left middle colic nodes, supporting segmental (left hemicolectomy) resection as the procedure of choice. Additional development of colonic sentinel node mapping using these techniques may contribute to individualized surgical therapy morbidity. See Video Abstract at http://links.lww.com/DCR/A495.

Mechanical characterization of human gastrocolic ligament until failure.

Road accidents can lead to abdominal injuries ranging from severe to lethal, that include hemorrhage of organs and their attachment system. A good understanding and prediction of abdominal injuries therefore requires investigation of the mechanical properties of the attachment systems of abdominal organs. In particular, the gastrocolic ligament (GCL) is one major link between the stomach and the transverse colon. This study aims to investigate the mechanical properties of the GCL under very low and high strain rate uniaxial tensile tests until failure. Thirty-five GCL samples were dissected from 7 embalmed cadavers and tested at a rate of 1 mm/s and 1 m/s. Incidence of freezing was also evaluated. The mechanical response of GCL samples showed an approximately bilinear curve. Within the first linear region (less than 5% of ligament strain), the apparent elastic modulus was estimated at 247±144 kPa, while in the second region, it was estimated at 690±282 kPa. The average failure stress (σfail) and failure strain (εfail) were 131.6±50 kPa and 29%±8%, respectively. High strain rate loading also showed high sensitivity to strain rate. The estimated GCL mechanical properties in this study can be implemented in finite element models of the abdomen to further investigate the mechanical contribution of the organ attachment system under traumatic loading conditions.

Nicotine-induced neurogenic relaxation in the mouse colon: changes with dextran sodium sulfate-induced colitis.

Nicotine has been shown to reduce both tone and muscular activity in the human colon by releasing nitric oxide (NO) from nerves. To our knowledge, however, the effect of nicotine on mouse colon has not been elucidated, and the response in tissue from ulcerative colitis (UC) has not been investigated. We examined nicotine-induced responses in colon from control mice and mice with dextran sodium sulfate (DSS)-induced UC. In controls, bath application of nicotine caused a transient relaxation in longitudinal preparations from the transverse and distal colons but not from the rectum. The response was observed in the presence of bethanechol, abolished by treatment with tetrodotoxin and hexamethonium, and mediated partially (>50%) by the NO pathway. In longitudinal preparations of the distal colon from DSS-treated mice, spontaneous contractions decreased markedly, and nicotine caused contraction without relaxation in half of the preparations tested. Nicotine-induced relaxation in the presence of bethanechol was significantly decreased in the DSS-treated distal colon without changing bethanechol-induced contractions. These data suggest that 1) responses to nicotine differ dependent on colon regions, 2) DSS treatment predominantly caused nicotine-sensitive neurogenic changes in distal colon, and 3) DSS treatment may reverse the direction of nicotine-evoked responses in the colon, in mice.

A pharmacological action of vitamin E unrelated to its antioxidant capacity.

The pharmacological action of vitamin E on the mechanical activity of isolated guinea pig colonic smooth muscle was examined in normoxic and hypoxic conditions. In hypoxia, but not normoxia, alpha-tocopherol (1-160 microM) evoked rapid concentration-dependent contractions from the colon. This was also seen with other members of the vitamin E family, and potency measurements gave EC(50) values (microM) of 10.6 +/- 0.9 for D-alpha-tocopherol, 6.0 +/- 1.2 for D-beta-tocopherol, 7.5 +/- 0.7 for D-gamma-tocopherol, and 6.1 +/- 1.5 for D-delta-tocopherol. This order of potency for the components of the vitamin differs from previously studied bioassay systems and from their antioxidant activity. A range of potent natural and synthetic antioxidants was not active in this system. Compounds with structural similarities to the side chain of vitamin E produced similar stimulatory responses and some, like phytol, were more potent than the vitamin (EC(50): 1.0 +/- 0.2 microM), whereas ring structures related to the vitamin, like Trolox C, antagonized the stimulant responses in a concentration-dependent manner. Therefore, this model system measures, directly, vitamin E-induced responses through a mechanism that does not appear to be related to the known antioxidant capacity of these agents.

[Study on the biomechanical behavior of human intestine].

To investigate the biomechanical behavior of human intestines. The tensile test human intestine was performed with the electronic tension machine in this paper. The results indicate that the exponential relationship for the stress-strain of the human intestine was obtained, and the exponential coefficient a of each segment of the intestine is almost the same although the constant C is different. It also shows that the relative rate of stretch length of each segment intestines is different in longitudinal and circumferential directions. And the incremental elastic modulus of colon is less than those of small intestine. It is considered that the colon can be more easily deformed. The experimental results provide the theoretic basis for research on intestinal endoscopic microrobot.

Electrophysiologic identification of the location of the colonic pacemakers in humans: further study.

We recently defined the sites of four colonic pacemakers that appear to generate the electric waves assumed to be responsible for the colonic motility. We hypothesized that a dysfunction of one or more of these pacemakers might interfere with the generation of electric waves and the colonic motility. This hypothesis was investigated in the current communication. The tests were performed during the repair of huge incisional hernia of 8 subjects (5 F, 3 M; mean age 42.8 +/- 3.3 SD years). Two electrodes were applied to each of the terminal ileum (TI), cecum (C), and ascending (AC), transverse (TC), descending (DC), and sigmoid (SC) colon. The electric activity of the TI and the various colonic segments was recorded using surface silver-silver chloride electrodes applied to the colon. The site of change of the wave variables between the TI and the C and between the different other colonic segments was determined by changing the position of the electrodes placed over the segments to be examined. Presumably, the sites where the wave variables changed represent the potential location of the pacemakers. We anesthetized these sites individually by injection of 2% Xylocaine, and then recorded the electric activity after 20 min in all the subjects and after 2 h in only 5 subjects. Electric waves in the form of pacesetter and action potentials were recorded from the TI and the colon. The sites of potential pacemakers could be defined at the ileocecal and cecocolonic junctions, at the mid third of the TC, and at the colosigmoid junction. Anesthetization of the cecal pole resulted in disappearance of the cecal electric waves, with persistence of the waves from the other colon segments. Anesthetization of the cecocolonic junction eliminated the electric waves of the AC and the right half of the TC, while the waves in the rest of the colon persisted. The remaining two pacemaker sites produced similar results when anesthetized. The electric waves reappeared after the anesthetic effect had waned. Thus, the colon possesses at least four pacemakers that appear to mediate the colonic motor activity. Individual pacemaker block by anesthetization effected disappearance of electric waves in the relative colonic segment, which reappeared after waning of the anesthetic effect. The disappearance of these waves upon pacemaker anesthetization supports a relationship between the pacemakers at the anesthetized site and the electric waves. The electric waves seem to be generated by these pacemakers. We suggest that colonic inertia, segmental or total, results from the dysfunction of one or more pacemakers, and that an artificial pacemaker could be applied for the treatment of such conditions. These suggestions need to be further studied.