BackgroundA 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.ObjectiveTo investigate the regulation of stem cell-driven tissue renewal by canonical Wnt and TGFβ/bone morphogenetic protein (BMP) pathways in the native human colonic epithelium.DesignIntact 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.ResultsNative human colonic crypts exhibited distinct activation profiles for canonical Wnt, TGFβ 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 TGFβ 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.ConclusionsSteady-state tissue renewal in the native human colonic epithelium is dependent on canonical Wnt signals combined with suppressed TGFβ/BMP pathways. Stem/progenitor cell proliferation is uncoupled from crypt cell migration and shedding, and is required to constantly replenish the crypt cell population.

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Letrozole is a drug used in the treatment of postmenopausal women with breast and ovarian tumours. There is no evidence in the literature indicating its use in treating gastric cancer. We present a 68 year old lady admitted from the emergency department with weight loss, malaise and anaemia. Investigations confirmed the presence of two different primary tumours in the left breast and the stomach. Following that this patient with oestrogen receptor positive breast cancer and oestrogen receptor negative gastric cancer was treated with letrozole for her breast cancer followed by a gastric resection. Independent histology by two pathologists pre-operatively diagnosed gastric adenocarcinoma. Post-operatively, independent analysis of the resected stomach, omentum and lymph nodes revealed no evidence of gastric cancer. Therefore we conclude that there is a possibility of letrozole having an effect on gastric cancer. Further studies are needed.

Laparoscopic Adjustable Gastric Banding (LAGB) was done for the first time in Belgium in 1993. Gastric torsion after band slippage is extremely rare. Literature review of gastric banding and complications in pregnancy did not reveal any case of gastric torsion. Hence, we report this rare case of gastric torsion in a pregnant lady following gastric banding.