Does human endometrial LGR5 gene expression suggest the existence of another hormonally regulated epithelial stem cell niche?

STUDY QUESTION

Is human endometrial leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5) gene expression limited to the postulated epithelial stem cell niche, stratum basalis glands, and is it hormonally regulated?

SUMMARY ANSWER

LGR5 expressing cells are not limited to the postulated stem cell niche but LGR5 expression is hormonally regulated.

WHAT IS KNOWN ALREADY

The human endometrium is a highly regenerative tissue; however, endometrial epithelial stem cell markers are yet to be confirmed. LGR5 is a marker of stem cells in various epithelia.

STUDY DESIGN, SIZE, DURATION

The study was conducted at a University Research Institute. Endometrial samples from 50 healthy women undergoing benign gynaecological surgery with no endometrial pathology at the Liverpool Women's hospital were included and analysed in the following six sub-categories; proliferative, secretory phases of menstrual cycle, postmenopausal, those using oral and local progestagens and samples for in vitro explant culture.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In this study, we used the gold standard method, in situ hybridisation (ISH) along with qPCR and a systems biology approach to study the location of LGR5 gene expression in full thickness human endometrium and Fallopian tubes. The progesterone regulation of endometrial LGR5 was examined in vivo and in short-term cultured endometrial tissue explants in vitro. LGR5 expression was correlated with epithelial proliferation (Ki67), and expression of previously reported epithelia progenitor markers (SOX9 and SSEA-1) immunohistochemistry (IHC).

MAIN RESULTS AND THE ROLE OF CHANCE

LGR5 gene expression was significantly higher in the endometrial luminal epithelium than in all other epithelial compartments in the healthy human endometrium, including the endometrial stratum basalis (P < 0.05). The strongest SSEA-1 and SOX9 staining was observed in the stratum basalis glands, but the general trend of SOX9 and SSEA-1 expression followed the same cyclical pattern of expression as LGR5. Stratum functionalis epithelial Ki67-LI and LGR5 expression levels correlated significantly (r = 0.74, P = 0.01), however, they did not correlate in luminal and stratum basalis epithelium (r = 0.5 and 0.13, respectively). Endometrial LGR5 demonstrates a dynamic spatiotemporal expression pattern, suggesting hormonal regulation. Oral and local progestogens significantly reduced endometrial LGR5 mRNA levels compared with women not on hormonal treatment (P < 0.01). Our data were in agreement with in silico analysis of published endometrial microarrays.

LARGE SCALE DATA

We did not generate our own large scale data but interrogated publically available large scale data sets.

LIMITATIONS, REASONS FOR CAUTION

In the absence of reliable antibodies for human LGR5 protein and validated lineage markers for the various epithelial populations that potentially exist within the endometrium, our study does not formally characterise or examine the functional ability of the resident LGR5+ cells as multipotent.

WIDER IMPLICATIONS OF THE FINDINGS

These data will facilitate future lineage tracing studies in the human endometrial epithelium; to identify the location of stem cells and further complement the in vitro functional studies, to confirm if the LGR5 expressing epithelial cells indeed represent the epithelial stem cell population.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by funding from the Wellbeing of Women project grant (RTF510) and Cancer Research UK (A14895). None of the authors have any conflicts of interest to disclose.

Novel application of high-dose rate brachytherapy for severe, recalcitrant palmoplantar pustulosis

Palmoplantar pustulosis (PPP) is a chronic pustular dermatitis of the palms and soles, which is frequently associated with significant pruritus and pain, often limiting daily activities. We present the case of a 36-year-old man with severe PPP who had treatment failure with multiple medical therapies but showed marked improvement with high-dose rate brachytherapy. Brachytherapy has the advantage of providing a conformal dose distribution over complex curved surfaces, such as the foot and ankle. Our observations suggest that brachytherapy may be a well-tolerated treatment option for patients with severe, refractory PPP.

The stem cells of small intestinal crypts: where are they?

Recently, there has been resurgence of interest in the question of small intestinal stem cells, their precise location and numbers in the crypts. In this article, we attempt to re-assess the data, including historical information often omitted in recent studies on the subject. The conclusion we draw is that the evidence supports the concept that active murine small intestinal stem cells in steady state are few in number and are proliferative. There are two evolving, but divergent views on their location (which may be more related to scope of capability and reversibility than to location) several lineage labelling and stem cell self-renewing studies (based on Lgr5 expression) suggest a location intercalated between the Paneth cells (crypt base columnar cells (CBCCs)), or classical cell kinetic, label-retention and radiobiological evidence plus other recent studies, pointing to a location four cell positions luminally from the base of the crypt The latter is supported by recent lineage labelling of Bmi-1-expressing cells and by studies on expression of Wip-1 phosphatase. The situation in the human small intestine remains unclear, but recent mtDNA mutation studies suggest that the stem cells in humans are also located above the Paneth cell zone. There could be a distinct and as yet undiscovered relationship between these observed traits, with stem cell properties both in cells of the crypt base and those at cell position 4.

Haematopoietic lineage-committed bone marrow cells, but not cloned cultured mesenchymal stem cells, contribute to regeneration of renal tubular epithelium after HgCl 2 -induced acute tubular injury

OBJECTIVE

Our previous studies have demonstrated that endogenous bone arrow cells (BMCs) contribute to renal tubular regeneration after acute tubular injury. The aim of this study was to examine which fraction of BMCs, haematopoietic lineage marrow cells (HLMCs) or mesenchymal stem cells (MSCs), are effective.

MATERIALS AND METHODS

Six-week-old female mice were lethally irradiated and were transplanted with female enhanced green fluorescent protein-positive (GFP(+)), plastic on-adherent marrow cells (as a source of HLMCs) plus cloned cultured male GFP(-) MSCs. Four weeks later, they were assigned into two groups: control mice with vehicle treatment and mice treated with HgCl2. Tritiated thymidine was given 1 h before animal killing which occurred at intervals over 2 weeks. Kidney sections were stained for a tubular epithelial marker, cell origin indicated by GFP immunohistochemistry or Y chromosome in situ hybridization; periodic acid-Schiff staining was performed, and samples were subjected to autoradiography. One thousand consecutive renal tubular epithelial cells per mouse, in S phase, were scored as either female (indigenous) GFP+(HLMC-derived) or male (MSC-derived).

RESULTS

Haematopoietic lineage marrow cells and MSCs stably engrafted into bone marrow and spleen, but only HLMC-derived cells, not MSCs, were found in the renal tubules and were able to undergo DNA synthesis after acute renal injury. A few MSCs were detected in the renal interstitium, but their importance needs to be further explored.

CONCLUSION

Haematopoietic lineage marrow cells, but not cloned cultured MSCs, can play a role not only in normal wear-and-tear turnover of renal tubular cells, but also in repair after tubular injury.

Exogenous bone marrow cells do not rescue non-irradiated mice from acute renal tubular damage caused by HgCl2, despite establishment of chimaerism and cell proliferation in bone marrow and spleen

OBJECTIVE

Various studies have shown that bone marrow stem cells can rescue mice from acute renal tubular damage under a conditioning advantage (irradiation or cisplatin treatment) favouring donor cell engraftment and regeneration; however, it is not known whether bone marrow cells (BMCs) can contribute to repair of acute tubular damage in the absence of a selection pressure for the donor cells. The aim of this study was to examine this possibility.

MATERIALS AND METHODS

Ten-week-old female mice were assigned into control non-irradiated animals having only vehicle treatment, HgCl(2)-treated non-irradiated mice, HgCl(2)-treated non-irradiated mice infused with male BMCs 1 day after HgCl(2), and vehicle-treated mice with male BMCs. Tritiated thymidine was given 1 h before animal killing.

RESULTS

Donor BMCs could not alleviate non-irradiated mice from acute tubular damage caused by HgCl(2), deduced by no reduction in serum urea nitrogen combined with negligible cell engraftment. However, donor BMCs could home to the bone marrow and spleen and display proliferative activity. This is the first report to show that despite no preparative myeloablation of recipients, engrafted donor BMCs can synthesize DNA in the bone marrow and spleen.

CONCLUSIONS

Exogenous BMCs do not rescue non-irradiated mice from acute renal tubular damage caused by HgCl(2), despite establishment of chimerism and cell proliferation in bone marrow and spleen.

Individual crypt genetic heterogeneity and the origin of metaplastic glandular epithelium in human Barrett's oesophagus

OBJECTIVES

Current models of clonal expansion in human Barrett's oesophagus are based upon heterogenous, flow-purified biopsy analysis taken at multiple segment levels. Detection of identical mutation fingerprints from these biopsy samples led to the proposal that a mutated clone with a selective advantage can clonally expand to fill an entire Barrett's segment at the expense of competing clones (selective sweep to fixation model). We aimed to assess clonality at a much higher resolution by microdissecting and genetically analysing individual crypts. The histogenesis of Barrett's metaplasia and neo-squamous islands has never been demonstrated. We investigated the oesophageal gland squamous ducts as the source of both epithelial sub-types.

METHODS

Individual crypts across Barrett's biopsy and oesophagectomy blocks were dissected. Determination of tumour suppressor gene loss of heterozygosity patterns, p16 and p53 point mutations were carried out on a crypt-by-crypt basis. Cases of contiguous neo-squamous islands and columnar metaplasia with oesophageal squamous ducts were identified. Tissues were isolated by laser capture microdissection and genetically analysed.

RESULTS

Individual crypt dissection revealed mutation patterns that were masked in whole biopsy analysis. Dissection across oesophagectomy specimens demonstrated marked clonal heterogeneity, with multiple independent clones present. We identified a p16 point mutation arising in the squamous epithelium of the oesophageal gland duct, which was also present in a contiguous metaplastic crypt, whereas neo-squamous islands arising from squamous ducts were wild-type with respect to surrounding Barrett's dysplasia.

CONCLUSIONS

By studying clonality at the crypt level we demonstrate that Barrett's heterogeneity arises from multiple independent clones, in contrast to the selective sweep to fixation model of clonal expansion previously described. We suggest that the squamous gland ducts situated throughout the oesophagus are the source of a progenitor cell that may be susceptible to gene mutation resulting in conversion to Barrett's metaplastic epithelium. Additionally, these data suggest that wild-type ducts may be the source of neo-squamous islands.

Biology of intestinal metaplasia in 2008: more than a simple phenotypic alteration

This review concentrates on one main aspect of cancerization in the oesophagus and stomach: principally, intestinal metaplasia. There are at least two other important pathways that lead to cancer and do not need such a morphological transformation. One is the gastric type of carcinoma on the Lauren classification, which arises directly from the stem cell zone and is the signet ring form of cancer, while the other is spasmolytic polypeptide-expressing metaplasia (SPEM)--spasmolytic polypeptide (TFF2) expressing metaplasia, where the gastric glands become filled with TFF2-expressing cells and may also lead to gastric dysplasia and cancer. The development of intestinal metaplasia is complex. Here, we examine intestinal metaplasia in molecular terms, noting the over-expression of Cdx1, Cdx2, Pdx1, Oct1, TFF3 and the downregulation of Hedgehog signalling; Runx3 is deactivated by epigenetic silencing, and pathways such as Wnt and MARK/ERK are involved. These changes start to explain the principles of the development of intestinal metaplasia and suggest that the regulation of these genes is of importance in the development of gastric cancer.

Side populations of gastrointestinal cancers are not enriched in stem cells

The side population (SP) phenotype, defined as the reserpine-blockable ability to efflux the nucleic acid dye Hoechst 33342, has been claimed to be enriched for stem cells in several human normal tissues, cancers and cell lines, and thus may be useful for the identification and isolation of cancer stem cells. We demonstrated the presence of SP fractions in all of seven tested gastrointestinal cancer cell lines. Four cell lines were selected (HT29, HGT101, Caco2 and HRA19a1.1) for detailed phenotypic and behavioural analysis with respect to stem cell characteristics. Cell surface marker analysis showed that, contrary to non-SP cells, the SPs entirely lack the expression of CD34. This difference, however, disappeared when the cells were cultured, rendering both populations CD34-positive. Expression of other putative stem cell markers (CD133, CD44, Hes-1, beta-catenin, Musashi-1, Oct-4 and CD117) was identical on SP and non-SPs before and after culturing. Sorted SP and non-SP cells were similarly clonogenic in vitro, tumourigenic in vivo, and displayed similar multipotential differentiation potential in vitro and in vivo. Additionally, culturing cytometrically-sorted SP and non-SP cells showed that the populations are interconvertible, each giving rise to the other. Expression of ABCG2 and Mdr-1, two membrane transporter proteins that have been suggested to be responsible for the drug-effluxing capacities of SP cells, including Hoechst 33342, was identical in non-SP and SP cells, indicating that there may be additional factors responsible for the Hoechst effluxing property in gastrointestinal cancer SP cells. Here, we show that the SP and non-SP fractions, albeit phenotypically distinct populations, do not differ with respect to stem cell-like cell number or behaviour. We thus conclude that the concept of the SP phenotype as a universal marker for stem cells does not apply to gastrointestinal cancer cells. These findings stand in contrast to the observations made in many other tissues and harbour important implications for the future search for intestinal cancer stem cell markers.

The development of duodenal microadenomas in FAP patients: the human correlate of the Min mouse

The morphological changes associated with the adenoma-carcinoma sequence are well documented in the colorectum. Small intestinal carcinogenesis is thought to progress through a similar adenoma-to-carcinoma pathway, but there is a relative dearth of studies examining the associated morphological changes. The best-known mouse model of intestinal neoplasia, the multiple intestinal neoplasia (Min) mouse, has been criticized as a genetic model of intestinal neoplasia, as the majority of its tumours occur in the small intestine. We examined pancreatico-duodenal resection specimens from seven familial adenomatous polyposis (FAP) patients. Serial sections of these were stained with haematoxylin and eosin for beta-catenin and its downstream target CD44, for BMPR1a, lysozyme, carbonic anhydrase II, and with MIB-1. Individual dysplastic crypts were isolated and mutations in the FAP (APC) gene compared between the top and bottom of the crypt. We found that: (a) duodenal microadenomas are extremely common in FAP patients; (b) these grow in the core of duodenal villi, forming lesions similar to those described in the Min mouse; (c) many lesions arise as monocryptal adenomas and grow by a process of crypt fission and branching; (d) migrating adenomatous cells lose their dysplastic phenotype as they migrate up the crypt villous axis; and (e) Paneth cells lose positional information.

IN CONCLUSION

(a) the morphological similarity of adenomas in the Min mouse and human suggest the Min mouse is a good model of FAP; (b) duodenal adenomas in FAP originate in monocryptal adenomas and follow the 'bottom-up' rather than the 'top-down' model of morphogenesis; (c) early microadenomas show evidence of cellular differentiation; (d) defects in the positioning of Paneth cells suggests disruption of the EphB2:EphB3 receptor system.

Reduced Shh expression in TFF2-overexpressing lesions of the gastric fundus under hypochlorhydric conditions

Expression of sonic hedgehog (Shh), a morphogen for the gastric fundic glands, is reduced in the atrophic mucosa that develops in association with Helicobacter pylori infection, resulting in impaired differentiation of the fundic gland cells, increased expression of trefoil factor family 2 (TFF2) and the formation of spasmolytic polypeptide (SP)-expressing metaplasia (SPEM), a preneoplastic lesion. However, it is still unresolved whether H. pylori-induced inflammation and the resultant reduction in parietal cell number or reduced parietal cell function per se reduces Shh expression. The present study was designed to clarify the expression of Shh and TFF2 in the context of parietal cell dysfunction in the absence of inflammation, using histamine H(2) receptor-knockout (H(2)R-null) mice and an acid exposure model. Age-matched H(2)R-null mice and wild-type (WT) mice were used. The expression of Shh and TFF2 mRNA was quantified by quantitative RT-PCR. Immunohistochemistry was also performed to detect the expression of Shh, TFF2 and cell markers. To study the effects of acid exposure, HCl solution was administered to the animals. The H(2)R-null mice exhibited higher gastric pH, increased TFF2 expression and reduced Shh expression. Impaired mucous neck-to-zymogenic cell differentiation was observed in the H(2)R-null mice. Furthermore, Shh expression increased in the presence of gastric acid and showed a significant correlation with gastric surface pH. In conclusion, our results suggest that persistent parietal cell dysfunction alone (suppressed gastric acid secretion), in the absence of inflammation or parietal cell loss caused by H. pylori infection, may be sufficient to down-regulate Shh expression in TFF2-overexpressing preneoplastic lesions of the gastric fundus. Since exposure to acid restored fundic Shh expression, appropriate gastric acid secretion may play an important role in the morphogen dynamics involved in the maintenance of gastric fundic gland homeostasis.

The cellular origin and proliferative status of regenerating renal parenchyma after mercuric chloride damage and erythropoietin treatment

OBJECTIVES

In this study, we have sought to establish the cellular origin and proliferative status of the renal parenchyma as it regenerates after damage induced by mercuric chloride, with or without erythropoietin treatments, that might alter the response.

MATERIALS AND METHODS

Female mice were irradiated and male whole bone marrow was transplanted into them. Six weeks later recipient mice were assigned to one of four groups: control, mercuric chloride treated, erythropoietin treated and treated with mercuric chloride plus erythropoietin.

RESULTS

Tubular injury scores were high 3 days after mercuric chloride and had recovered partially after 14 days, in line with serum urea nitrogen levels. Confocal microscopy confirmed the tubular location of bone marrow-derived cells. A 'four-in-one' analytical technique (identifying cell origin, tubular phenotype, tubular basement membranes and S-phase status) revealed that tubular necrosis increased bone marrow derivation of renal tubular epithelium from a baseline of approximately 1.3% to approximately 4.0%. Erythropoietin increased the haematocrit, but no other effects were detected.

CONCLUSION

As 1 in 12 proximal tubular cells in S-phase was derived from bone marrow, we conclude that in the kidney, the presence of bone marrow-derived cells makes a minor but important regenerative contribution after tubular necrosis.

Expansion of a mutated clone: from stem cell to tumour

Intestinal stem cells are adult, tissue-based stem cells located at the base of the intestinal crypt and are capable of regenerating all intestinal cell types. The progeny of mutated stem cells can expand to fill an entire crypt as a consequence of genetic drift, selective advantage or hitchhiking-eventually forming a clonal crypt population by a process called "niche succession". Cancer is believed to be a disease of stem cells. The digestive tract has a very high cancer prevalence partly due to rapid epithelial cell turnover and exposure to dietary toxins. Work on the hereditary cancer syndromes, including familial adenomatous polyposis (FAP), has led to significant advances, including the adenoma-carcinoma sequence. The initial mutation involved in this stepwise progression is in the "gatekeeper" tumour suppressor gene adenomatous polyposis coli (APC). In FAP somatic, second hits in this gene are non-random events, selected for by the position of the germline mutation. The early growth of adenomas is contentious, with two main theories, the "top-down" and "bottom-up" hypotheses, attempting to explain the spread of dysplastic tissue in the bowel. Initial X chromosome inactivation studies suggested that colorectal tumours were monoclonal; however, work on a rare XO/XY human patient with FAP and chimeric Min mice showed that approximately 76% of adenomas were polyclonal. A reduction in tumour multiplicity in the chimeric mouse model has been achieved by the introduction of a homozygous tumour resistance allele. This model has been used to suggest that short-range interaction between adjacent initiated crypts, not random polyp collision, is responsible for tumour polyclonality.

Stem cells and cancer: an intimate relationship

Tumour-wide 'omics' approaches have long held sway as the approach to identifying useful therapeutic targets. This view is changing with the realization that many, if not all, cancers contain a minority population of self-renewing stem cells, the cancer stem cells, which are entirely responsible for sustaining the tumour as well as giving rise to proliferating but progressively differentiating cells that are responsible for much of the cellular heterogeneity that is so familiar to histopathologists. Moreover, although many tumours probably have their origins in normal stem cells, persuasive evidence from the haematopoietic system suggests that genetic alterations in more committed progenitor cells can reactivate the self-renewal machinery, resulting in a further source of cancer stem cells. Thus, the bulk of the tumour is not the problem, and so the identification of cancer stem cells and the factors that regulate their behaviour are likely to have an enormous bearing on the way that we treat neoplastic disease in the future.

Bone marrow transplantation ameliorates pathology in interleukin-10 knockout colitic mice

The authors have previously reported the derivation of colonic subepithelial myofibroblasts (SEMFs) in both humans and mice from bone marrow (BM). In the pathogenesis of inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis, colonic SEMFs mediate several types of inflammatory response. In the present study, interleukin (IL)-10-/- mice were used as a model of IBD to investigate the involvement of BM-derived cells in the inflamed mucosa. Male whole BM [either C57/BL10 (wild type: WT) or IL-10-/- donor mice] was used to perform bone marrow transplantation (BMT) into both WT and IL-10-/- female mice. Tissue samples were evaluated by immunohistochemistry for alpha-smooth muscle actin expression and by in situ hybridization using a Y-chromosome-specific probe to track the donor-derived colonic SEMFs. The mucosal expression of mRNA for pro-inflammatory cytokines was analysed by reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, mRNA expression of matrix metalloproteinase (MMP)-7 and osteopontin in the inflamed mucosa was assessed using in situ hybridization. Body weights and histological scores showed that IL-10-/- mice that received WT BM had an improved course of colitis, decreased mucosal pro-inflammatory mRNA expression, and up to 30% of their SEMFs were of BM origin. Conversely, IL-10-/- mice receiving IL-10-/- BM progressed to extensive colitis, and Y probe analysis revealed that up to 45% of colonic SEMFs were of BM origin. WT mice receiving IL-10-/- or WT BM had no signs of colonic inflammation. The expression of MMP-7 and osteopontin was up-regulated in the inflamed mucosa. In conclusion, IL-10-/- mice displayed ameliorated disease activity after WT BMT, whilst colitis was not induced in WT mice by IL-10-/- BMT. The contribution of BM-derived cells to colonic SEMFs was significantly increased in the inflamed mucosa compared with non-inflamed mucosa.

Review article: from gastrin to gastro-oesophageal reflux disease--a century of acid suppression

To commemorate Edkins' discovery of gastrin in 1905, we review a century of progress in the physiology and pathobiology of gastrin and acid secretion especially as it pertains to clinical aspects of gastro-oesophageal reflux disease. Although initially ignored, Edkins' observations eventually led to the enthusiastic investigation of gastrin and acid regulation in peptic ulcer disease, culminating in important therapeutic advances in the management of acid peptic disease. Following the improved understanding of gastric secretory physiology, and the development of acid suppressants with increasing efficacy, the use of surgical intervention for peptic ulcer disease was almost eliminated. Surgery became obsolete with the discovery of Helicobacter pylori. Three other advances are also influencing modern practice: the gastrotoxicity of aspirin and non-steroidal anti-inflammatory drugs is now increasingly appreciated, the role of endoscopy in the diagnosis and therapy of upper gastrointestinal bleeding, and the use of intravenous acid-suppressive agents. The major issue for the future resides within the epidemic of gastro-oesophageal reflux disease. How to diagnose, categorize and treat this condition and how to identify and prevent neoplasia, are the challenges of the new century.

Trefoil factors: from ulceration to neoplasia

There is convincing evidence that trefoil factors (TFFs) do play an important role in tumourigenesis. However, their specific roles in cancer are not yet clear. Recently, TFFs have been shown to interfere with crucial biological processes such as cell proliferation, differentiation, apoptosis and angiogenesis. Research on the function of TFFs and its relationship with specific signal transduction pathways has also advanced significantly. As a consequence, some ideas about the role of TFFs in cancer have started to take shape. The objective of this review is to summarize and discuss current knowledge on the relationship between TFFs and cancer.

From gene mutations to tumours--stem cells in gastrointestinal carcinogenesis

Stem cells share many properties with malignant cells, such as the ability to self-renew and proliferate. Cancer is believed to be a disease of stem cells. The gastrointestinal tract has high cancer prevalence partly because of rapid epithelial cell turnover and exposure to dietary toxins. The molecular pathways of carcinogenesis differ according to the tissue. Work on hereditary cancer syndromes including familial adenomatous polyposis (FAP) has led to advances in our understanding of the events that occur in tumour development from a gastrointestinal stem cell. The initial mutation involved in the adenoma-carcinoma sequence is in the 'gatekeeper' tumour-suppressor gene adenomatous polyposis coli (APC). Somatic hits in this gene are non-random in FAP, with the type of mutation selected for by the position of the germline mutation. In the stomach, a metaplasia-dysplasia sequence occurs and is often related to Helicobacter pylori infection. Clonal expansion of mutated cells occurs by niche succession. Further expansion of the aberrant clone then occurs by the longitudinal division of crypts into two daughter units--crypt fission. Two theories seek to explain the early development of adenomas--the 'top down' and 'bottom up' hypotheses. Initial studies suggested that colorectal tumours were monoclonal; however, later work on chimeric mice and a sex chromosome mixoploid patient with FAP suggested that up to 76% of early adenomas were polyclonal. Introduction of a homozygous resistance allele has reduced tumour multiplicity in the mouse and has been used to rule out random collision of polyps as the cause of these observations. It is likely that short-range interaction between adjacent initiated crypts is responsible for polyclonality.

Markers of adult tissue-based stem cells

The expectation generated by the pluripotentiality of embryonic stem (ES) cells has initiated a renaissance in stem cell biology. While ES cells can be harvested in abundance and appear to be the most versatile of cells for regenerative medicine, adult stem cells also hold promise, but the identity and subsequent isolation of these comparatively rare cells remains problematic in most tissues, perhaps with the notable exception of the bone marrow. Identifying surface molecules (markers) that would aid in stem cell isolation is thus a major goal for stem cell biologists. Moreover, the characterization of normal stem cells in specific tissues may provide a dividend for the treatment of cancer. There is a growing belief that the successful treatment of neoplastic disease will require specific targeting of the cancer stem cells, cells that may well have many of the characteristics of their normal counterparts.

Intestinal stem cells

The intestinal tract has a rapid epithelial cell turnover, which continues throughout life. The process is regulated and maintained by a population of stem cells, which give rise to all the intestinal epithelial cell lineages. Studies in both the mouse and the human show that these cells are capable of forming clonal crypt populations. Stem cells remain hard to identify, however it is thought that they reside in a 'niche' towards the base of the crypt and their activity is regulated by the paracrine secretion of growth factors and cytokines from surrounding mesenchymal cells. Stem cell division is usually asymmetric with the formation of an identical daughter stem cell and committed progenitor cells. Progenitor cells retain the ability to divide until they terminally differentiate. Occasional symmetric division produces either 2 daughter cells with stem cell loss, or 2 stem cells and eventual clone dominance. This stochastic extinction of stem cell lines with eventual dominance of one cell line is called 'niche succession'. The discovery of plasticity, the ability of stem cells to engraft into, and in some cases replace the function of damaged host tissues has generated a large amount of scientific and clinical interest: however the concept remains controversial and is still a subject of hot debate. Studies are beginning to identify the complex molecular, genetic and cellular pathways underlying stem cell function such as Wnt signalling, bone morphogenetic protein (BMP) and Notch/Delta pathways. The derangement of these pathways within stem cells plays an integral part in the development of malignancy within the intestinal tract.

Gastrointestinal Stem Cells and Cancer: Bridging the Molecular Gap

Cancer is believed to be a disease involving stem cells. The digestive tract has a very high cancer prevalence partly owing to rapid epithelial cell turnover and exposure to dietary toxins. Work on the hereditary cancer syndromes including familial adenomatous polyposis (FAP) has led to significant advances, including the adenoma-carcinoma sequence. The initial mutation involved in this stepwise progression is in the "gatekeeper" tumor suppressor gene adenomatous polyposis coli (APC). In FAP somatic, second hits in this gene are nonrandom events, selected for by the position of the germ-line mutation. Extensive work in both the mouse and human has shown that crypts are clonal units and mutated stem cells may develop a selective advantage, eventually forming a clonal crypt population by a process called "niche succession." Aberrant crypt foci are then formed by the longitudinal division of crypts into two daughter units--crypt fission. The early growth of adenomas is contentious with two main theories, the "top-down" and "bottom-up" hypotheses, attempting to explain the spread of dysplastic tissue in the bowel. Initial X chromosome inactivation studies suggested that colorectal tumors were monoclonal; however, work on a rare XO/XY human patient with FAP and chimeric Min mice showed that 76% of adenomas were polyclonal. A reduction in tumor multiplicity in the chimeric mouse model has been achieved by the introduction of a homozygous tumor resistance allele. This model has been used to suggest that short-range interaction between adjacent initiated crypts, not random polyp collision, is responsible for tumor polyclonality.

Circulating mesenchymal stem cells

Mesenchymal precursor cells (MPCs) are multipotent cells capable of differentiating into various mesenchymal tissues, such as bone, cartilage, fat, tendon and muscle. They are present within both mesenchymal tissues and the bone marrow (BM). If marrow-derived MPCs are to have a role in repair and fibrosis of mesenchymal tissues, transit of these cells through the peripheral blood is to be expected. Although there is evidence for the existence of MPCs within the peripheral blood, results are debated and are not always reproducible. Variations in the methods of cell purification, culture and characterisation may explain the inconsistent results obtained in different studies.

Aberrant epithelial expression of trefoil family factor 2 and mucin 6 in Helicobacter pylori infected gastric antrum, incisura, and body and its association with antralisation

AIMS

To determine gastric expression of trefoil family factor 2 (TFF2) and MUC6 in Helicobacter pylori positive and negative subjects, and its association with antralisation at the gastric incisura.

METHODS

Gastric biopsies from the antrum, incisura, and body of 76 dyspeptic patients without ulcers were used for the determination of H. pylori infection, histological changes, and epithelial TFF2 and MUC6 expression.

RESULTS

In the foveola, the rates of TFF2 and MUC6 immunostaining were greater in H. pylori infected (n = 27) than in uninfected patients (n = 49) at the antrum (59.3% v 4.1% for TFF2 and 63.0% v 4.1% for MUC6; both p < 0.001) and incisura (44.4% v 2.0% for TFF2 and 48.1% v 0% for MUC6; both p < 0.001). In the deeper glands, the rates were also greater in H. pylori infected than in uninfected patients at the incisura (85.2% v 22.4% for both TFF2 and MUC6; p < 0.001). Antral-type mucosa was present at the incisura in 28 of the 76 patients. TFF2 and MUC6 expression in the foveola and deeper glands was significantly associated with antral-type mucosa, independent of H. pylori status.

CONCLUSIONS

Helicobacter pylori infection increases the expression of TFF2 and MUC6 in the gastric epithelium. Aberrant TFF2 and MUC6 expression is associated with antralisation of gastric incisura.

The gastrointestinal stem cell

The longevity of adult stem cells, and their potential for vast tissue regeneration, makes them a focal point of current research and debate, with future aspirations for the use of stem cells in the treatment of a number of human pathological conditions. Due to the rapid rate of cell turnover in the gastrointestinal tract, the stem cells of this tissue are amongst the most assiduous in the body, although they remain unidentified to this day due to their immature, undifferentiated phenotype. However, our knowledge of the mechanisms regulating gastrointestinal stem cell function is evolving, with the identification of putative cellular markers and the elucidation of signalling pathways which regulate cell behaviour in the normal and neoplastic gastrointestinal tract. This review describes the fundamental properties of the gastrointestinal stem cell including: (i) their number, location and origins, (ii) their primary function of deriving gastrointestinal cell lineages and maintaining tissue homeostasis, (iii) the acquisition of gastrointestinal cell lineages from adult stem cells of extraneous tissues and the consequences of this in a therapeutic context, and (iv) the genetic and morphological phenomena surrounding neoplastic transformation in the gastrointestinal tract.

Recipes for adult stem cell plasticity: fusion cuisine or readymade?

A large body of evidence supports the idea that certain adult stem cells, particularly those of bone marrow origin, can engraft at alternative locations, particularly when the recipient organ is damaged. Under strong and positive selection pressure these cells will clonally expand/differentiate, making an important contribution to tissue replacement. Similarly, bone marrow derived cells can be amplified in vitro and differentiated into many types of tissue. Despite seemingly irrefutable evidence for stem cell plasticity, a veritable chorus of detractors has emerged, some doubting its very existence, motivated perhaps by more than a little self interest. The issues that have led to this situation include the inability to reproduce certain quite startling observations, and extrapolation from the behaviour of embryonic stem cells to suggest that adult bone marrow cells simply fuse with other cells and adopt their phenotype. Although these issues need resolving and, accepting that cell fusion does appear to allow reprogramming of haemopoietic cells in special circumstances, criticising this whole new field because some areas remain unclear is not good science.

Gastric stem cells: an update

Cells of the gastric mucosa undergo constant renewal, the rate depending on the health of the tissue (inflammation, ulceration, carcinogenesis). While much attention has been focused on the mechanism of mucosal damage and the pathogenesis of ulceration, there has recently been the recognition that elucidation of the nature of the gastric stem cell lineages as well as the regulators of phenotype expression of this system may yield considerable biological information as well as open the door to the identification of areas of therapeutic relevance. Chimeric and X-inactivation studies in mice and humans demonstrate that each region of the gastric mucosa is morphologically diverse (antrum is different to the fundus), with its own repertoire of cell types and glandular structures. The current evidence suggests that a single stem cell in every gastric gland indirectly gives rise to a clone of all differentiated cells, by production of committed progenitor cells. It is also this multipotential cell that produces new crypts by crypt fission, repairs entire crypts when damaged, and gives rise to the ulcer-associated cell lineage and gastric carcinomas. It is likely that this stem cell occupies a niche in the isthmus composed of mesenchymal cells and extracellular matrix factors, which regulates the function of the cell via mesenchymal-epithelial cross talk. The molecular events (IGF-signaling) that regulate the development of the gastric gland in the mice have begun to be understood. Ultimately, the identification of these pathways will play an important role in identifying new molecular targets for the treatment of gastric disease.

The new stem cell biology: something for everyone

The ability of multipotential adult stem cells to cross lineage boundaries (transdifferentiate) is currently causing heated debate in the scientific press. The proponents see adult stem cells as an attractive alternative to the use of embryonic stem cells in regenerative medicine (the treatment of diabetes, Parkinson's disease, etc). However, opponents have questioned the very existence of the process, claiming that cell fusion is responsible for the phenomenon. This review sets out to provide a critical evaluation of the current literature in the adult stem cell field.

Use of the 'nutriceutical', bovine colostrum, for the treatment of distal colitis: results from an initial study

BACKGROUND

Bovine colostrum is a rich source of nutrients, antibodies and growth factors.

AIM

To examine the efficacy of colostrum enemas in the treatment of distal colitis using a randomized, double-blind, controlled protocol.

METHODS

Fourteen patients (eight female), with a mean age of 45 years (range, 16-75 years) and mild to moderately severe distal colitis (Powell-Tuck scoring system), received colostrum enema (100 mL of 10% solution) or placebo (albumin solution) b.d. for 4 weeks. Both groups also received mesalazine (1.6 g/day) or, if already taking it, had a dose increment of 1.6 g/day. Disease activity was documented at 0, 2 and 4 weeks.

RESULTS

After 4 weeks, the colostrum group showed a mean reduction in symptom score of - 2.9 (95% confidence interval (CI), - 5.4 to - 0.3), whereas the placebo group showed a mean response of + 0.5 (95% CI, - 2.4 to +3.4). The histological score improved in five of the eight patients in the colostrum group (mean response, - 0.9; 95% CI, - 1.69 to - 0.03), whereas the histological scores only improved in two of the six patients in the placebo group (mean response, 0.2; 95% CI, - 2.4 to +2.6).

CONCLUSIONS

Bovine colostrum enema shows potential as a novel therapy for left-sided colitis with additional benefits over using mesalazine alone. Further studies appear to be warranted.

Bone marrow derivation of pericryptal myofibroblasts in the mouse and human small intestine and colon

BACKGROUND AND AIMS

In order to establish whether extraintestinal cells contribute to the turnover and repair of gastrointestinal tissues, we studied the colons and small intestines of female mice that had received a male bone marrow transplant, together with gastrointestinal biopsies from female patients that had developed graft versus host disease after receiving a bone marrow transplant from male donors.

METHODS

Using in situ hybridisation to detect Y chromosomes and immunohistochemistry, we demonstrated that cells derived from injected bone marrow frequently engrafted into the intestine and differentiated into pericryptal myofibroblasts.

RESULTS

In the human intestine, we confirmed by combining in situ hybridisation with immunostaining for smooth muscle actin that the bone marrow derived cells within the intestine exhibited a myofibroblast phenotype. In female mouse recipients of male bone marrow grafts, we observed colocalisation of Y chromosomes and clusters of newly formed marrow derived myofibroblasts. While few of these were present at seven days after bone marrow transplantation, they were numerous at 14 days, and by six weeks entire columns of pericryptal myofibroblasts could be seen running up the sides of crypts in both the small intestine and colon. These columns appeared to extend into the villi in the small intestine. Within the intestinal lamina propria, these Y chromosome positive cells were negative for the mouse macrophage marker F4/80 antigen and CD34.

CONCLUSIONS

Bone marrow derived pericryptal myofibroblasts were present in the mouse intestine following irradiation and bone marrow transplant, and in the intestines of human patients suffering graft versus host disease following a bone marrow transplant. Our data indicate that bone marrow cells contribute to the regeneration of intestinal myofibroblasts and epithelium after damage, and we suggest that this could be exploited therapeutically.

Hepatic and renal differentiation from blood-borne stem cells

The recognition that adult bone marrow stem cells (BMSCs) can traffic into the liver and kidney and differentiate into a variety of cell types such as epithelial cells, endothelial cells and myofibroblasts has caused excitement. This has expanded our knowledge of how these organs regenerate following damage and provides new opportunities for therapeutic exploitation. BMSC transplants have already been used to correct a murine model of metabolic liver disease. Bone marrow stem cells that transdifferentiate into long-lasting cells within the liver and kidney are proposed as suitable targets for gene therapy and may be used in the correction of single gene defects, or the delivery of antiviral and anti-inflammatory genes to the liver and kidney. There is growing evidence that BMSCs can repopulate the endothelium of transplanted livers and kidneys and thus may potentially be manipulated to induce graft tolerance within solid organ transplants. However, there are technical barriers to be overcome before the theoretical benefits of this exiting new area becomes a practical prospect.

Lectins can reverse the distal intestinal atrophy associated with elemental diets in mice

BACKGROUND

Elemental diets cause intestinal atrophy and reduced intestinal integrity, which can lead to significant increases in intestinal permeability and bacterial translocation. Recently, several lectins have been shown to have trophic effects on the intestine.

AIMS

We examined the effects of concanavalin-A and phytohaemagglutinin on cell proliferation and crypt fission throughout the intestine of mice fed on elemental diets.

METHODS

Mice were randomized to chow fed, elemental diet, elemental diet plus concanavalin-A and elemental diet plus phytohaemagglutinin groups. Cell proliferation and crypt fission were estimated in microdissected crypts. Plasma gastrin and enteroglucagon levels were measured by radioimmunoassay.

RESULTS

Elemental diet feeding significantly decreased cell proliferation and crypt fission of the middle and distal small intestine and throughout the colon. Phytohaemagglutinin significantly increased the weight of the intestine, but concanavalin-A had little effect. Cell proliferation in the small intestine was significantly increased by both lectins. However, in the stomach and colon, only phytohaemagglutinin increased proliferation. Crypt fission in the colon was dramatically increased by phytohaemagglutinin. Phytohaemagglutinin increased the plasma gastrin level, but not the enteroglucagon level.

CONCLUSIONS

Lectins have significant trophic effects on the small intestine and colon of mice fed elemental diets, and these actions vary between different sites in the gastrointestinal tract.

Histogenesis of human colorectal adenomas and hyperplastic polyps: the role of cell proliferation and crypt fission

BACKGROUND

The histogenesis of human colorectal hyperplastic polyps and colorectal adenomas is poorly understood even now.

METHOD

Human colorectal adenomas, hyperplastic polyps, and normal colorectal mucosae (patients with familial adenomatous polyposis and hereditary non-polyposis colorectal carcinoma were excluded) were obtained during colonoscopy and microdissected into individual crypts. Morphology, cell proliferation characteristics, and fission indices of crypts isolated from these lesions were then studied.

RESULTS

Crypts isolated from colorectal adenomas and colorectal hyperplastic polyps were significantly larger (p<0.001) than crypts from normal colorectal mucosae. Crypt fission was an uncommon event in normal colonic mucosae but common in crypts isolated from adenomas and hyperplastic polyps (p<0.001). Analysis of the distribution of mitoses suggested an upward expansion of the proliferation compartment in adenomas to the surface of the crypt with no reversal of proliferating cell distribution, as has previously been described.

CONCLUSIONS

Sporadic human colorectal adenomas and hyperplastic polyps grow by the process of crypt fission. Expansion of the proliferative compartment was demonstrated in crypts from adenomas, consistent with deregulation of cell cycle control.

Comprehensive analysis of SMAD4 mutations and protein expression in juvenile polyposis: evidence for a distinct genetic pathway and polyp morphology in SMAD4 mutation carriers

Juvenile polyposis syndrome (JPS; OMIM 174900) is a rare disorder which is characterized by the presence of hamartomatous polyps throughout the gastrointestinal tract and an increased risk of gastrointestinal malignancy. Mutations of the SMAD4 gene on chromosome 18q21.1 have been shown to cause a subset of JPS cases, with estimates ranging from 20% to >50%. Characterization of the genes that cause the remainder of JPS cases relies on the certainty that SMAD4 is not the causative gene. We have undertaken a comprehensive analysis of germline SMAD4 mutations in a cohort of JPS patients to define the spectrum of mutations that cause JPS. We have analyzed a series of polyps from these patients for SMAD4 protein expression. We have also performed a blinded assessment of polyp material to look for morphological differences between polyps from patients with and without a germline SMAD4 mutation. The results indicate that almost all germline SMAD4 mutations are readily detectable by screening genomic DNA using polymerase chain reaction-based methods; SMAD4 can be excluded as the causative gene in the majority of our JPS cohort. Loss of SMAD4 expression occurs in most polyps from SMAD4 mutation carriers, even those with missense germline mutations. SMAD4 loss in polyps is, however, not a feature of cases that are not caused by SMAD4 mutations, indicating that these polyps develop along a SMAD4-independent pathway. The morphology of polyps from SMAD4 mutation carriers is subtly different from other JPS polyps, notably including a more prominent epithelial component in the former.

Glicentin, an active enteroglucagon, has a significant trophic role on the small intestine but not on the colon in the rat

BACKGROUND

Many experiments have indicated that the gut glucagons (enteroglucagons) are associated with cell proliferation in the small intestine. However, recent studies have failed to show trophic effects of glicentin (enteroglucagon) on the intestine.

AIMS

To examine the effects of glicentin on intestinal proliferation in vivo in the rat.

METHODS

Rats were established on total parenteral nutrition for 6 days. Four experimental groups were given daily doses of 1, 4, 20 and 80 microg/rat of glicentin via the jugular vein. Rats fed by total parenteral nutrition and rats fed chow ad libitum were used as controls. Tissues taken from the duodenum, jejunum, ileum and colon were fixed in Carnoy's fluid and microdissected to determine the metaphase arrest scores and crypt fission ratios.

RESULTS

The mean metaphase arrest scores per crypt of the small intestine were significantly increased in the rats given 4, 20 and 80 microg of glicentin. These responses were dose-dependent, and were most prominent in the ileum. Crypt fission of the ileum was significantly decreased in the 20 and 80 microg glicentin groups. Glicentin had no effects on proliferation or fission in the colon.

CONCLUSIONS

Glicentin is trophic to the rat small intestine, but not the colon.

Bone marrow contributes to renal parenchymal turnover and regeneration

In order to establish whether extra-renal cells contribute to the turnover and repair of renal tissues, this study examined kidneys of female mice that had received a male bone marrow transplant and kidney biopsies from male patients who had received kidney transplants from female donors. By using in situ hybridization to detect Y-chromosomes it could be demonstrated that circulating stem cells frequently engraft into the kidney and differentiate into renal parenchymal cells. In the human renal grafts it was confirmed that some of the recipient-derived cells within the kidney exhibited a tubular epithelial phenotype, by combining in situ hybridization with immunostaining for the epithelial markers CAM 5.2 and the lectin Ulex europaeus. Female mouse recipients of male bone marrow grafts showed co-localization of Y-chromosomes and tubular epithelial markers Ricinus communis and Lens culinaris, and a specific cytochrome P450 enzyme (CYP1A2) indicating an appropriate functional capability of clustered newly formed marrow-derived tubular epithelial cells. Y-chromosome-containing cells were observed within glomeruli, with morphology and location appropriate for podocytes. Within the murine kidney, these Y-chromosome-positive cells were negative for the mouse macrophage marker F4/80 antigen and leukocyte common antigen, but were vimentin-positive. The presence of bone marrow-derived cells was noted in both histologically normal mouse kidneys and in human transplanted kidneys suffering damage from a variety of causes. These data indicate that bone marrow cells contribute to both normal turnover of renal epithelia and regeneration after damage, and it is suggested that this could be exploited therapeutically.

Effect of ectopic expression of rat trefoil factor family 3 (intestinal trefoil factor) in the jejunum of transgenic mice

To further examine the function of the trefoil factor family (TFF), the expression of which is up-regulated at sites of injury, we have produced transgenic mice that chronically express rat TFF3 within the jejunum (using a rat fatty acid-binding protein promoter). The expression of rat TFF3 was limited to the villi of the jejunum and had no effect on base-line morphology. Rat TFF3 expression did result, however, in a reduced sensitivity to indomethacin (85 mg/kg subcutaneously), which only caused a 29% reduction in villus height in transgenics versus 51% reduction in controls (p < 0.01). Indomethacin increased initial intestinal epithelial cell proliferation and migration, but the presence of rat TFF3 caused no additional change in proliferation (bromodeoxyuridine), cell migration ([(3)H]thymidine and bromodeoxyuridine), apoptosis (terminal deoxyuridine nucleotidyl nick end labeling), or E-cadherin immunostaining. In vitro studies following changes in resistance of intestinal strips in Ussing chambers (voltage-clamp technique) showed increased base-line resistance in the rat TFF3-expressing region (326 +/- 60 versus 195 +/- 48 ohm.cm(2) in controls, p < 0.05) and reduced the fall in resistance following HCl exposure by about 40% (p < 0.01). Overexpression of TFF3 stabilizes the mucosa against noxious agents, supporting its role in mucosal protection/repair. It may therefore provide a novel approach to the prevention and/or treatment of intestinal ulceration.

Use of ambulatory electrocardiography for detection of ventricular premature complexes in healthy dogs

OBJECTIVE

To evaluate the use of 24-hour ambulatory electrocardiography (AECG) for the detection of ventricular premature complexes (VPC) in healthy dogs.

DESIGN

Case series.

ANIMALS

50 healthy mature dogs.

PROCEDURE

A 24-hour AECG was performed on each dog and evaluated for the presence of VPC.

RESULTS

Fifty dogs weighing between 18.2 to 40.9 kg (40 and 90 lb) representing 13 breeds were evaluated; there were 4 sexually intact females, 21 spayed females, 4 sexually intact males, and 21 castrated males. Ages ranged from 1 to 12 years. Thirty-four dogs had no VPC; 16 dogs had between 1 and 24 VPC. The grade of arrhythmia ranged from 1 to 4, with 4 dogs having an arrhythmia with a grade > 1. Significant differences were not detected between the group of dogs with VPC and those without VPC with regard to sex, age, and minimum, maximum, or mean heart rate.

CONCLUSIONS AND CLINICAL RELEVANCE

We conclude that healthy mature dogs have infrequent VPC, as detected by use of 24-hour AECG. The presence of numerous or sequential VPC may be suggestive of cardiac or systemic disease and may indicate the need for thorough clinical evaluation.

Clinical features of dilated cardiomyopathy in Great Danes and results of a pedigree analysis: 17 cases (1990-2000)

OBJECTIVE

To determine clinical features of dilated cardiomyopathy (DCM) in Great Danes and to determine whether DCM is familial in this breed.

DESIGN

Retrospective study.

ANIMALS

17 Great Danes with DCM.

PROCEDURE

Medical records of Great Danes in which DCM was diagnosed on the basis of results of echocardiography (fractional shortening < 25%, end-systolic volume index > 30 ml/m2 of body surface area) were reviewed. Pedigrees were obtained for affected animals, as well as for other Great Danes in which DCM had been diagnosed.

RESULTS

Dilated cardiomyopathy appeared to be familial and was characterized by ventricular dilatation, congestive heart failure (left-sided or biventricular), and atrial fibrillation. Pedigree analysis suggested that DCM was inherited as an X-linked recessive trait, but the mode of inheritance could not be definitively identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that DCM may be an X-linked recessive trait in Great Danes. Thus, dogs with DCM probably should not be used for breeding, and female offspring of affected dogs should be used cautiously. Male offspring of affected females are at an increased risk of developing DCM and should be evaluated periodically for early signs of disease. Results of pedigree analysis were preliminary and should be used only as a guide for counseling breeders, rather than as a basis for making breeding decisions.

Comparison of in-hospital versus 24-hour ambulatory electrocardiography for detection of ventricular premature complexes in mature Boxers

OBJECTIVE

To evaluate the use of in-hospital electrocardiography (ECG) for detection of ventricular premature complexes (VPC), compared with 24-hour ambulatory ECG.

DESIGN

Original study.

ANIMALS

188 Boxers > 9 months old; 31 had a history of syncope, and 157 were healthy (no history of syncope).

PROCEDURE

In-hospital ECG was performed on all Boxers for at least 2 minutes. Within 7 days after the in-hospital ECG was completed, 24-hour ambulatory ECG was performed.

RESULTS

The specificity of in-hospital ECG was 100% for the detection of at least 50 VPC in a 24-hour period in dogs with syncope and 93% in healthy dogs. In-hospital ECG had poor sensitivity, although sensitivity increased as the number of VPC per 24 hours increased.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of in-hospital ECG is highly specific for detection of at least 50 VPC during a 24-hour period. However, in-hospital ECG is insensitive, and a lack of VPC does not suggest that the dog does not have a substantial number of VPC during that same period. The use of in-hospital ECG appears to be inadequate for screening purposes and therapeutic evaluations in mature Boxers with ventricular arrhythmic disease.

Coordinated localisation of mucins and trefoil peptides in the ulcer associated cell lineage and the gastrointestinal mucosa

BACKGROUND AND AIMS

Trefoil factor family (TFF) peptides and the chromosome 11p15.5 mucin glycoproteins are expressed and secreted in a site specific fashion along the length of the gastrointestinal tract. Evidence for coexpression of mucins and trefoil peptides has been suggested in numerous gastrointestinal mucosal pathologies. The ulcer associated cell lineage (UACL) occurs at sites of chronic ulceration in Crohn's disease, expresses all three trefoil peptides, and is implicated in mucosal restitution. We tested the hypothesis that individual trefoil peptides are uniquely localised with specific mucins in the UACL and normal gastrointestinal epithelia.

METHODS

Expression of mucin genes in the UACL from small bowel tissue of patients with Crohn's disease was detected by in situ hybridisation, and localisation of the products by immunohistochemistry. Colocalisation of mucins and trefoil peptides was demonstrated by immunofluorescent colabelling in UACL and normal gastrointestinal epithelia.

RESULTS

MUC5AC and TFF1 were colocalised in distal ductular and surface elements of the UACL and in foveolar cells of the stomach, whereas MUC6 and TFF2 were colocalised to acinar and proximal ductular structures in the UACL, in the fundus and deep antral glands of the stomach, and in Brunner's glands of the duodenum. MUC5B was found sporadically throughout the UACL and gastric body. MUC2 was absent from the UACL, Brunner's glands, and stomach. MUC2 and TFF3 were colocalised throughout the large and small bowel mucosa.

CONCLUSIONS

The UACL has a unique profile of mucin gene expression. Coordinated localisation of trefoil peptides and mucins in UACL and normal gastrointestinal epithelia suggests they may assist each others' functions in protection and repair of gastrointestinal mucosa.

Effects of pemoline on spontaneous and event-related electrical activity of the brain

The effect of pemoline on the electrical activity of the brain (electroencephalogram, EEG) was studied in relation to time since sleep and time of day in 6 healthy subjects carrying out periods of work lasting 18 h. Power of the spontaneous EEG increased with time since sleep and amplitude of the P3 event-related response decreased. The changes may be interpreted as the reduction in alertness with time awake. In contrast, pemoline decreased power of the spontaneous EEG and increased the amplitude the P3 response, effects that are consistent with improved alertness. The changes in brain activity were paralleled by effects on performance, in terms of percentage of correct responses and reaction time. Performance decreased with time awake, and was improved by pemoline compared with placebo. The drug counteracted the adverse effects of time since sleep, with the beneficial effect of the drug persisting over the 18-hour period of work. The findings emphasise that spontaneous and event-related activity of the EEG may be used both to complement measures of performance in the laboratory and to assess behaviour in occupational situations where performance testing is impractical.

Duodenal-content reflux esophagitis induces the development of glandular metaplasia and adenosquamous carcinoma in rats

Recent studies have demonstrated that refluxed duodenal contents cause esophageal carcinoma in rats without exposure to carcinogens. The histopathological spectrum of these carcinomas includes squamous-cell carcinoma, adenocarcinoma and adenosquamous carcinoma. Pure adenocarcinomas are thought to arise in areas of columnar metaplasia adjacent to the anastomosis, similar to Barrett's esophagus in humans. In contrast, the histogenesis of adenosquamous carcinomas is unclear. The purpose here was to investigate the pathogenesis of esophageal adenosquamous carcinomas in a time-course experiment of chronic duodenal-content reflux without carcinogen. Forty-two 8-week-old male Sprague-Dawley rats were divided into seven groups and exposed to duodenal-content esophageal reflux during 10, 15, 20, 25, 30, 35 and 40 weeks, respectively. All animals underwent an esophagojejunostomy with gastric preservation in order to produce chronic esophagitis. The rats received a standard diet without addition of carcinogens. An increasing incidence of glandular metaplasia and carcinoma was observed over the time course, starting at 20 weeks. After 40 weeks of reflux, multiple foci of glandular metaplasia and adenosquamous carcinoma were found in 83 and 50% of the animals, respectively. Most of the carcinomas occurred in the middle and proximal esophagus and had a dual pattern of differentiation, glandular and squamous. These findings confirm that duodenal content reflux alone has a carcinogenic effect. We propose that chronic duodenal reflux induces the development of metaplastic cells with glandular differentiation from the stem cells of squamous epithelium, and that glandular metaplastic foci are the morphological element from which tumors with a dual pattern of differentiation arise.

Endogenous peptides and peptide therapy in gut defense and repair

The gastrointestinal tract shows a remarkable ability to withstand injury. Factors important in maintaining integrity include rapid proliferation, an excellent blood supply and, in the stomach and colon, the presence of a protective mucus layer. When an injury occurs, the healing process consists of an initial phase of cell migration (restitution), followed by an increase in proliferation and remodeling. There is now a large body of evidence suggesting that at least 30 different peptides are involved in maintaining mucosal integrity and in stimulating the repair process. Insights into the pathophysiological function of these peptides can be gained from considering them as belonging to broad groups based on their overall role in maintaining gut growth or in stimulating repair. Considered in this way, they can be usefully compartmentalized into: 1) mucosal integrity peptides, which are predominantly involved in maintaining normal mucosal integrity; 2) luminal surveillance peptides, which are constantly present in the lumen but which only stimulate proliferation and repair at sites of injury; and 3) rapid response peptides, whose production is rapidly regulated at sites of injury and the function of which is to stimulate the repair process. If peptide therapy for gastrointestinal conditions is to be used, potential methods of delivery include oral, systemic and gene therapy; however, orally delivered peptides may be digested in the gut lumen, systemic administration may result in side effects at sites distant to the gut and methodological problems remain when considering gene therapy. Peptides play a key role in maintaining mucosal homeostasis in the gut. Over the next five years, recombinant peptides are likely to be increasingly used to treat a wide variety of gastrointestinal disorders such as inflammatory bowel disease and necrotizing enterocolitis.