Biomedical subjects
Publications and source records attributed to Angela Webb.
Our understanding of adult epidermal stem cells has increased substantially over the last two decades especially; however even more detailed knowledge is imperative for realizing potential medical therapies. We need to know how to identify these cells and what regulates their function. In this review, we describe the literature to date and elucidate the clinical relevance of these findings.
BACKGROUND: In a rural centre with limited resources and no endoscopic retrograde cholangiopancreatography facilities, a prospective cohort study was established to compare policies of routine and selective intraoperative cholangiography (IOC) in order to develop a local protocol. METHODS: Patients undergoing laparoscopic cholecystectomy from 1 February 1995 to 30 November 2002 were allocated to undergo routine or selective IOC according to birth date. Those with known common bile duct (CBD) stones were excluded. Selective IOC was performed on the basis of abnormal liver function tests or a dilated CBD on ultrasound. Study end points after 12 months follow-up were retained CBD stones, CBD injury, operating times and the effect of IOC on the management of patients with persistent biliary symptoms postoperatively. RESULTS: Of the 148 patients in the routine group, 94 underwent IOC and CBD stones were shown in 12. Of the 155 in the selective group, IOC was performed in 34 of 45 eligible patients and stones were shown in five. Sixteen patients re-presented with recurrent biliary symptoms or jaundice postoperatively and eight had proven retained CBD stones, of whom only one had undergone (false-negative) IOC. There was no significant difference in mean operating time (56 vs 61 min; t-test P = 0.15). There was one CBD injury in each group, both incurred after successful IOC. CONCLUSIONS: There was no difference between policies of routine or selective IOC in relation to operating times, retained CBD stone rates or CBD injury. However, the authors found management of patients with recurrent biliary symptoms easier if an IOC had been performed, and IOC was easier to perform when the staff were expecting it. Thus a policy of routine IOC has been adopted.
The location and identity of interfollicular epidermal stem cells of adult human skin remain undefined. Based on our previous work in both adult murine and neonatal human foreskin, we demonstrate that cell surface levels of the alpha6 integrin and the transferrin receptor (CD71) are valid markers for resolving a putative stem cell, transit amplifying and differentiating compartment in adult human skin by flow cytometry. Specifically, epidermal cells expressing high levels of alpha6 integrin and low levels of the transferrin receptor CD71 (phenotype alpha6 (bri)CD71(dim)) exhibit several stem cell characteristics, comprising a minor population (2%-5%) of the K14(bri) fraction, enriched for quiescent and small blast-like cells with high clonogenic capacity, lacking the differentiation marker K10. Conversely, the majority of K14(bri) K10(neg) epidermal cells express high levels of CD71 (phenotype alpha6 (bri)CD71(bri)), and represent the actively cycling fraction of keratinocytes displaying greater cell size due to an increase in cytoplasmic area, consistent with their being transient amplifying cells. The alpha6 (bri)CD71(bri) population exhibited intermediate clonogenic capacity. A third population of K14(dim) but K10 positive epidermal cells could be identified by their low levels of alpha6 integrin expression (i.e. alpha6 (dim) cells), representing the differentiation compartment; predictably, this subpopulation exhibited poor clonogenic efficiency. Flow cytometric analysis for the hair follicle bulge region (stem cell) marker K15 revealed preferential expression of this keratin in alpha6 (bri) cells (i.e., both stem and transient amplifying fractions), but not the alpha6 (dim) population. Given that K15 positive cells could only be detected in the deep rete ridges of adult skin in situ, we conclude that stem and transient amplifying cells reside in this location, while differentiating (K15 negative) cells are found in the shallow rete ridges.