A mathematical model of intestinal oedema formation

Comparison of Postoperative Outcome and Prognosis Among Laparoscopic Left Colectomy and Laparoscopic Sigmoidectomy in Sigmoid Colon Cancer Patients: A Propensity Score Matching Study

PURPOSE

The purpose of this study was to investigate the effect of laparoscopic left colectomy (LLC) and laparoscopic sigmoidectomy (LSD) on short-term outcomes and prognosis of sigmoid colon cancer (SCC) patients using propensity score matching (PSM).

METHODS

In this retrospective study, the SCC patients who underwent LLC or LSD surgery were collected from a single clinical center from Jan 2011 to Dec 2019. Short-term outcomes and prognosis were compared between patients who received LSD surgery and LLC surgery.

RESULTS

A total of 356 patients were included in this study. After 1:1 PSM analysis, there were 50 patients who underwent LLC surgery and 50 patients who underwent LSD surgery left in this study. No significant difference was found in baseline characteristics after PSM (P > .05). In comparison with the LLC surgery group, the LSD surgery group had shorter operation time (P = .003) after PSM. Moreover, the surgical procedure was not an independent predictor for overall survival (OS) (P = .918, 95% CI = .333-2.688) and disease-free survival DFS (P = .730, 95% CI = .335-2.150), but age (OS: P = .009, 95% CI = 1.010-1.075; DFS: P = .014, 95% CI = 1.007-1.061) and tumor stage (OS: P = .004, 95% CI = 1.302-3.844; DFS: P < .01, 95% CI = 1.572-4.171) were the independent risk factors for OS and DFS in SCC patients.

CONCLUSION

There was no significant difference between the two surgical procedures for prognosis of SCC patients. However, the possible reasons for changing the surgical procedures should be cautious by surgeons.

A comprehensive mathematical framework for modeling intestinal smooth muscle cell contraction with applications to intestinal edema

The contraction of intestinal smooth muscle cells (ISMCs) involves many coordinated biochemical and mechanical processes. In this work, we present a framework for modeling ISMC contractility that begins with chemical models of calcium dynamics, continues with myosin light chain phosphorylation and force generation, and ends with a cell model of the ISMC undergoing contraction-relaxation. The motivation for developing this comprehensive framework is to study the effects of edema (excess fluid build-up in the muscle tissue) on ISMC contractility. The hypothesis is that more fluid equates to dilution of an external stimulis, eventually leading to reduced contractility. We compare our results to experimental data collected from normal versus edematous intestinal muscle tissue.

Experimental evidence and mathematical modeling of thermal effects on human colonic smooth muscle contractility

It has been shown, in animal models, that gastrointestinal tract (GIT) motility is influenced by temperature; nevertheless, the basic mechanism governing thermal GIT smooth muscle responses has not been fully investigated. Studies based on physiologically tuned mathematical models have predicted that thermal inhomogeneity may induce an electrochemical destabilization of peristaltic activity. In the present study, the effect of thermal cooling on human colonic muscle strip (HCMS) contractility was studied. HCMSs were obtained from disease-free margins of resected segments for cancer. After removal of the mucosa and serosa layers, strips were mounted in separate chambers. After 30 min, spontaneous contractions developed, which were measured using force displacement transducers. Temperature was changed every hour (37, 34, and 31°C). The effect of cooling was analyzed on mean contractile activity, oscillation amplitude, frequency, and contraction to ACh (10(-5) M). At 37°C, HCMSs developed a stable phasic contraction (~0.02 Hz) with a significant ACh-elicited mean contractile response (31% and 22% compared with baseline in the circular and longitudinal axis, respectively). At a lower bath temperature, higher mean contractile amplitude was observed, and it increased in the presence of ACh (78% and 43% higher than the basal tone in the circular and longitudinal axis, respectively, at 31°C). A simplified thermochemomechanical model was tuned on experimental data characterizing the stress state coupling the intracellular Ca(2+) concentration to tissue temperature. In conclusion, acute thermal cooling affects colonic muscular function. Further studies are needed to establish the exact mechanisms involved to better understand clinical consequences of hypothermia on intestinal contractile activity.