Method of pedicle division during laparoscopic right hemicolectomy affects lymph node yield and short-term outcomes.

BACKGROUND: Several ways of performing laparoscopic right hemicolectomy (RHC) have evolved. The vascular pedicle can be divided into extracorporeal (RHC-EC) or intracorporeal (RHC-IC). It is not known whether vessel ligation during RHC-EC is as central as during RHC-IC. We compare these approaches in terms of pathological and short-term clinical outcomes. METHODS: Patients undergoing elective laparoscopic RHC in a single centre (July 2013-September 2016) were identified. Data collection included operative details, length of stay, complications, specimen parameters including number and involvement of lymph nodes and recurrence. RESULTS: One hundred and sixty-nine patients were included (94 RHC-IC, 75 RHC-EC). For caecal and ascending colon cancers, mesocolic width was greater after RHC-IC than RHC-EC (7.9 cm versus 6.6 cm, P < 0.05), as was lymph node yield (19.5 versus 17.3, P < 0.05). There was no significant difference in length of colon resected, distal resection margin, number of positive nodes, proportion of node-positive tumours and R1 rate. Operative duration was higher for RHC-IC (163 min versus 91 min, P < 0.001), as was incidence of ileus (35% versus 15%, P < 0.05). Length of stay also tended to be higher (7.4 days versus 6.0 days, P = 0.19). There was no difference in disease recurrence (follow-up 12 months). Body mass index was positively correlated with lymph node yield for RHC-EC, but not for RHC-IC. CONCLUSION: Lymph node yield after laparoscopic RHC is adequate, whether the vascular pedicle is taken intracorporeal or extracorporeal, supporting the use of both approaches. RHC-IC yields more lymph nodes and greater mesocolic width, but involves a longer operation and higher incidence of ileus.

Elevated O-GlcNAc levels activate epigenetically repressed genes and delay mouse ESC differentiation without affecting naïve to primed cell transition.

The differentiation of mouse embryonic stem cells (ESCs) is controlled by the interaction of multiple signaling pathways, typically mediated by post-translational protein modifications. The addition of O-linked N-acetylglucosamine (O-GlcNAc) to serine and threonine residues of nuclear and cytoplasmic proteins is one such modification (O-GlcNAcylation), whose function in ESCs is only now beginning to be elucidated. Here, we demonstrate that the specific inhibition of O-GlcNAc hydrolase (Oga) causes increased levels of protein O-GlcNAcylation and impairs differentiation of mouse ESCs both in serum-free monolayer and in embryoid bodies (EBs). Use of reporter cell lines demonstrates that Oga inhibition leads to a reduction in the number of Sox1-expressing neural progenitors generated following induction of neural differentiation as well as maintained expression of the ESC marker Oct4 (Pou5f1). In EBs, expression of mesodermal and endodermal markers is also delayed. However, the transition of naïve cells to primed pluripotency indicated by Rex1 (Zfp42), Nanog, Esrrb, and Dppa3 downregulation and Fgf5 upregulation remains unchanged. Finally, we demonstrate that increased O-GlcNAcylation results in upregulation of genes normally epigenetically silenced in ESCs, supporting the emerging role for this protein modification in the regulation of histone modifications and DNA methylation.

Canonical Wnt signals combined with suppressed TGFß/BMP pathways promote renewal of the native human colonic epithelium.

BACKGROUND: A defining characteristic of the human intestinal epithelium is that it is the most rapidly renewing tissue in the body. However, the processes underlying tissue renewal and the mechanisms that govern their coordination have proved difficult to study in the human gut. OBJECTIVE: To investigate the regulation of stem cell-driven tissue renewal by canonical Wnt and TGFß/bone morphogenetic protein (BMP) pathways in the native human colonic epithelium. DESIGN: Intact human colonic crypts were isolated from mucosal tissue samples and placed into 3D culture conditions optimised for steady-state tissue renewal. High affinity mRNA in situ hybridisation and immunohistochemistry were complemented by functional genomic and bioimaging techniques. The effects of signalling pathway modulators on the status of intestinal stem cell biology, crypt cell proliferation, migration, differentiation and shedding were determined. RESULTS: Native human colonic crypts exhibited distinct activation profiles for canonical Wnt, TGFß and BMP pathways. A population of intestinal LGR5/OLFM4-positive stem/progenitor cells were interspersed between goblet-like cells within the crypt-base. Exogenous and crypt cell-autonomous canonical Wnt signals supported homeostatic intestinal stem/progenitor cell proliferation and were antagonised by TGFß or BMP pathway activation. Reduced Wnt stimulation impeded crypt cell proliferation, but crypt cell migration and shedding from the crypt surface were unaffected and resulted in diminished crypts. CONCLUSIONS: Steady-state tissue renewal in the native human colonic epithelium is dependent on canonical Wnt signals combined with suppressed TGFß/BMP pathways. Stem/progenitor cell proliferation is uncoupled from crypt cell migration and shedding, and is required to constantly replenish the crypt cell population.