Molecular biology of Barrett's cancer

Oesophageal adenocarcinoma (OA) remains one of the more deadly forms of gastro-intestinal cancer with a mortality rate exceeding 90%. The incidence of OA remains unabated and has a reported fivefold increase since 1970 [Pera M, Cameron AJ, Trastek VF, Carpenter HA & Zinsmeister AR. Increasing incidence of adenocarcinoma of the esophagus and esophagogastric junction. Gastroenterology 1993; 104(2): 510-513]. Gastro-oesophageal reflux disease and its sequelae, Barrett's oesophagus, is one of the principle risk factors in the development of OA, with a 30-fold increased risk in Barrett's patients compared with the general population [Tytgat GNJ. Does endoscopic surveillance in esophageal columnar metaplasia (Barrett's-Esophagus) have any real value. Endoscopy 1995; 27(1): 19-26]. OA is thought to be a microcosm of evolution, developing sequentially along the metaplasia-dysplasia-adenocarcinoma sequence. Progression is attributed to a series of genetic and epigenetic events that ultimately allow for clonal selection of Barrett's cells via subversion of intrinsic control mechanisms regulating cellular proliferation and/or apoptosis. This review will describe the current suppositions of the mechanisms behind the selection and subsequent expansion of Barrett's clones, and focus on some of the principle hallmarks associated with this transition.

MAPK/AP-1 signal pathway in tobacco smoke-induced cell proliferation and squamous metaplasia in the lungs of rats

Overwhelming evidence has demonstrated tobacco smoke (TS) is causally associated with various types of cancers, especially lung cancer. Sustained epithelial cell hyperplasia and squamous metaplasia are considered as preneoplastic lesions during the formation of lung cancer. The cellular and molecular mechanisms leading to lung cancer due to TS are not clear. Mitogen-activated protein kinases (MAPK)/activator protein-1 (AP-1) can be activated by various stimuli and play a critical role in the control of cell proliferation and differentiation. To date, information on the response of the MAPK/AP-1 pathway during hyperplasia and squamous metaplasia induced by TS is lacking. We therefore investigated the effects of TS on the development of epithelial hyperplasia and squamous metaplasia, regulation of MAPK/AP-1 activation, and expression of AP-1-regulated cell cycle proteins and differentiation markers in the lungs of rats. Exposure of rats to TS (30 mg/m(3) or 80 mg/m(3), 6 h/day, 3 days/week for 14 weeks) dramatically induced cell proliferation and squamous metaplasia in a dose-dependent manner, effects that paralleled the activation of AP-1-DNA binding activity. Phosphorylated ERK1/2, JNK, p38 and ERK5 were significantly increased by exposure to TS, indicating the activation of these MAPK pathways. Expression of Jun and Fos proteins were differentially regulated by TS. TS upregulated the expression of AP-1-dependent cell cycle proteins including cyclin D1 and proliferating cell nuclear antigen (PCNA). Among the AP-1-dependent cell differentiation markers, keratin 5 and 14 were upregulated, while loricrin, filaggrin and involucrin were downregulated following TS exposure. These findings suggest the important role of MAPK/AP-1 pathway in TS-induced pathogenesis, thus providing new insights into the molecular mechanisms of TS-associated lung diseases including lung cancers.

[The significance of intestinal metaplasia related to gastric ulcer]

PURPOSE

Intestinal metaplasia is considered an intermediary stage of gastric carcinogenesis. Thus, we aim to investigate lesions of intestinal metaplasia diagnosed at patients with peptic ulcer.

MATERIAL AND METHODS

Our study was achieved on a group of 212 patients, clinically diagnosed with gastric ulcer and having partial gastrectomy. The fragments obtained from the circumference, the basis and from around the ulcer were formalin-fixed (10%) and paraffin included. The specimens were stained routinely (HE) and with special methods (van Gieson, Masson, Gomori, PAS and Alcian Blue).

RESULTS

Intestinal metaplasia was present in 36 cases (16.9%). It was noted as a unique lesion (in 10 cases), in association with chronic gastritis (23 cases) and with dysplasia (3 cases). Most of the cases (70%) displayed type I (complete) metaplasia characterized by the presence of enterocytes, goblet and Paneth cells. The glandular architecture was regular, with straight crypts, lined by mature, absorbtion cells and goblet cells producing sialomucins. 20% of the cases displayed type II (incomplete) metaplasia, with distort crypts, lined by a few absorptive and goblet cells and sparse Paneth cells. 10% of the cases presented type III (incomplete, colonic type) metaplasia with twisted crypts, increased cell density and stratification. The goblet cells in the adjacent mucosa of the malignant ulcers contained mainly sulphomucins, together with a few neutral mucins and sialomucins. The signification and the involvement of the intestinal metaplasia in the malignant transformation of the gastric ulcer are discussed.

CONCLUSION

Since it represents a risk factor for carcinogenesis the identification of intestinal metaplasia in the context of the gastric ulcer is extremely important.

Metaplasia in the pancreas

There is currently much interest in the possibility to treat chronic diseases by cell replacement or regenerative therapies. Most of these studies focus on the manipulation of undifferentiated stem cells. However, tissue repair and regeneration can also be achieved by differentiated cells, which, in certain conditions, can even transdifferentiate to other cell types. Such transdifferentiations can lead to tissue metaplasia. The pancreas is an organ wherein metaplasia has been well investigated and for which experimental models have been recently developed allowing to unravel the molecular basis of transdifferentiation. Pancreatic metaplasias studied so far include the conversion of exocrine acinar cells to duct cells, exocrine cells to endocrine islet cells, endocrine cells to duct cells, and acinar cells to hepatocytes. Epitheliomesenchymal transitions have also been described. The available evidence indicates that mature cells can be reprogrammed by specific environmental cues inducing the expression of cell type-specific transcription factors. For example, the glucocorticoid hormone dexamethasone induces pancreatic transdifferentiation to hepatocytes, whereas the combination of epidermal growth factor and leukemia-inhibitory factor induces exocrine-endocrine transdifferentiation in vitro. Further unravelling of the involved signal transduction pathways, transcription factor networks, and chromatin modifications is required to manipulate metaplasia at will and to apply it in tissue repair or regeneration.

High-magnification chromoscopic pouchoscopy: a novel in vivo technique for surveillance of the anal transition zone and columnar cuff following ileal pouch-anal anastomosis

BACKGROUND

Persistence of underlying disease in the residual rectal mucosa and anal transition zone (ATZ) following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis and familial adenomatous polyposis provides a site for potential malignancy. For this reason endoscopic surveillance is performed, although conventional assessment may be unreliable. We hypothesized that the novel technique of high-magnification chromoscopic pouchoscopy (HMCP) may permit accurate anatomical localization of this high risk zone in vivo and permit improved biopsy accuracy.

PATIENTS AND METHODS

We studied 132 patients with IPAA using HMCP. Three distinct zones were defined using magnification endoscopy: ATZ, appearing as a linear cellular marix; columnar cuff, identifiable by a type I crypt pattern; and ileal pouch body, appearing as villous projections. Quadrantic biopsies of these zones were taken in addition to biopsies of any other lesions noted.

RESULTS

A total of 1586 biopsies were taken from zones 1-3 (median, 12; range, 5-16 per patient). Overall biopsy-targeting accuracies using magnification guidance as compared with histopathology were 82%, 73% and 91% for the ATZ, cuff and pouch body, respectively. No dysplasia was identified in the quadrantic surveillance biopsies. Histologically confirmed columnar metaplasia was visualized in vivo using magnification chromoscopy. Patients with IPAA >3 years' duration were more likely to have pouch reservoir columnar metaplasia as compared to those <3 years (p<0.01). Pouch reservoir metaplasia was associated with a pre-morbid diagnosis of high-grade dysplasia or carcinoma within the premorbid colectomy specimen (p<0.001).

CONCLUSIONS

This is the first study to evaluate this novel application of high magnification chromoscopy. Magnification pouchoscopy is a valid predictor of ATZ and cuff anatomy, permitting accurate biopsy targeting. Further randomized studies validating this technique with an emphasis on dysplasia detection in larger cohorts are required.

Barrett's oesophagus and oesophageal adenocarcinoma: how does acid interfere with cell proliferation and differentiation?

Acid, a principal component of gastro-oesophageal refluxate, may contribute to the development and malignant progression of Barrett's oesophagus. Oesophageal pH monitoring studies have demonstrated that patients with Barrett's oesophagus have severe and chronic acid reflux. However, there is overlap between the amount of acid exposure in patients with oesophagitis compared with patients with Barrett's oesophagus. This suggests that factors other than acid may be important in the aberrant oesophageal cell differentiation process that leads to the development of the metaplastic Barrett's mucosa. The other factors important in the aetiology of Barrett's oesophagus are poorly understood but probably include both genetic and environmental factors.

Osseous metaplasia in the setting of nephrogenic fibrosing dermopathy

BACKGROUND

Nephrogenic fibrosing dermopathy (NFD) is a new skin-fibrosing disorder associated with renal dysfunction. It is marked by the acute onset of induration involving the upper and lower limbs, and it is characterized by distinctive histopathologic findings.

METHODS

We report the case of a patient on hemodialysis who presented initially with the characteristic clinical and pathological features of NFD. The patient progressively developed painful hyperkeratotic spicules on both thighs and bone metaplasia was confirmed.

RESULTS

Histological studies were performed at different stages of the disease showing an evolution from the well-known initial phase of NFD, characterized by thickening of the dermis, increased number of fibroblast-like cells, and mucin deposits, to an end stage characterized by the presence of dermal ossification.

CONCLUSIONS

We report the exceptional finding of bone metaplasia in the setting of a case of NFD.

What is the role of cytokeratins in Barrett/cardia differentiation?

The importance of distinguishing between Barrett metaplasia and intestinal metaplasia of the gastric cardia is now accepted, and the management of each entity is quite different. Patients with Barrett metaplasia are enrolled in surveillance programs, consisting of periodic endoscopy and biopsy, because of the known risk of developing adenocarcinoma of the esophagus. Patients with intestinal metaplasia of the gastric cardia, however, are not currently enrolled in such programs, because this condition carries a low risk of developing adenocarcinoma of the gastric cardia. The distinction between both conditions by morphologic examination of routine histologic sections of endoscopic biopsies is extremely difficult if at all possible. A group of investigators proposed the use of immunostains for cytokeratin (CK) 7 and CK20 to overcome such difficulty. They concluded that the Barrett CK7/CK20 pattern was a highly sensitive and specific marker for Barrett metaplasia. Their observations, however, were not confirmed by other investigators. However, because it may be associated with premalignant lesions elsewhere in the gastric mucosa, we propose that intestinal metaplasia of the gastric cardia may have the same clinical implication as Barrett metaplasia.

[The picture of abdominal cavity wall after surgical treatment of postoperative abdominal hernia with the Matapurkar's method of "peritoneal sandwich" in pathomorphological examinations]

In this work the results of autopsy are presented--of a 45 years old man who died because of complications of cirrhosis in 24 months after repairing a postoperative hernia with the Matapurkar's "peritoneal sandwich" and polypropylene mesh. Macroscopically and histopathologically it has been shown that gradual healing of the mesh ends with formation of alloplastic-tissue connective structure, called neofascia that fills in the defect in fascia of the abdominal wall. Inflammatory process around implanted mesh maintains even after several months. It seems that parietal peritoneum of hernia sac that surrounds polypropylene mesh may have a tendency towards metaplasia in the direction of tissue-connective fascia layer.

Pro- and anti-inflammatory cytokines gene polymorphisms and Helicobacter pylori infection: interactions influence outcome

The aim of this study was to evaluate whether there was any correlation between Helicobacter pylori-associated diseases and (1) H. pylori virulence genes or (2) IL-1B, IL-1RN, IFN-G, TNF-A, IL-10 genetic polymorphisms. Patients with non-cardia gastric cancer (NCGC, n=129) or benign gastroduodenal diseases (n=792) were studied. IL-1RN intron 2 VNTR polymorphism (PCR), IL-1B -31 C/T (RFLP), the SNPs of IFN-G (+874 A/T), TNF-A (-1031 C/T, -857 C/T, -376 A/G, -308 A/G, -238 A/G), IL-10 (-1082 A/G, -819 C/T, -592 A/C) (Taqman chemistry) were studied. cagA, s1 and m1 vacA, were PCR amplified. Duodenal ulcer was more frequent in TNF-A -857 TT and in IL-1RN 1,2 subjects. TNF-A -857 TT genotype was also correlated with gastric ulcer. IL-10 -819 TT genotype was associated with intestinal metaplasia and NCGC. Antral inflammation was associated with TNF-A -1031 TT, while corpus activity with IL-10 -819 CC. H. pylori infection was associated with TNF-A -308 AG genotype, while IFN-G +874 AA genotype was associated with cagA. In conclusion, among host genetic factors contributing to H. pylori disease outcome, IFN-G +874 AA genotype favors cagA positive infections, TNF-A -857 TT duodenal ulcer while IL-10 -819 TT intestinal metaplasia and NCGC.

Barrett metaplasia: reassessment of treatment and follow-up

PURPOSE OF REVIEW

The incidence of esophageal adenocarcinoma continues to rise in the Western world, with a mean 5-year survival of less than 20%. There has therefore been increasing interest in the precursor lesion, Barrett's esophagus. However, adenocarcinoma will not develop in most patients with Barrett's esophagus. This review summarizes the data on the management of Barrett's esophagus that have been published since January 2003.

RECENT FINDINGS

The control of reflux symptoms significantly improves quality of life, and surgical antireflux therapy may gradually cause regression of the Barrett segment compared with proton pump inhibitor therapy. The data substantiate the claim that the cancer risk in Barrett esophagus is lower than had hitherto been suggested. The risk factors for progression include increasing age and length of segment, macroscopic inflammatory changes, loss of heterozygosity over several genetic loci, and increased proliferation status. The extent of high-grade dysplasia may not accurately predict cancer development, and continued surveillance, rather than intervention, for such patients may decrease the chances of curative treatment. Long-term follow-up data are beginning to accumulate for nonsurgical treatment strategies. Chemoprevention trials are under way to evaluate the role of acid suppression and nonsteroidal anti-inflammatory drugs and their derivatives.

SUMMARY

At this time, endoscopic surveillance and surgical management remain the mainstay, but continued research efforts should enable risk stratification and cancer prevention in the future.

Cardiac mucosa in the remnant esophagus after esophagectomy is an acquired epithelium with Barrett's-like features

BACKGROUND

The cervical esophagus is normally lined by squamous epithelium and is usually not exposed to gastroesophageal reflux. The aims of this study were, first, to investigate whether cardiac mucosa can be acquired in the remnant cervical esophagus after esophagectomy and cervical esophagogastrostomy and, second, to characterize this mucosa if present.

METHODS

The medical records of 100 patients who had undergone esophagectomy with gastric pull-up reconstruction were studied retrospectively to identify those who had biopsies from the cervical esophagus proximal to the gastroesophageal anastomosis during postoperative follow-up. The histopathology and immunohistochemical stains were reviewed to assess similarity to Barrett's mucosa (cytokeratins [CK] 7 and 20 and DAS-1), cellular proliferation (topoisomerase 2alpha), and the potential for dysplasia (cyclo-oxygenase 2 [COX-2] and ornithine decarboxylase [ODC]).

RESULTS

Supra-anastomotic biopsies were performed in 20 patients. Cardiac mucosa was present in 10 of 20 (50%) patients in whom biopsies were performed. Four patients had areas of intestinal metaplasia, and dysplasia, and adenocarcinoma developed in 1 patient. The CK7/20 and DAS-1 staining of the columnar mucosa showed a pattern similar to Barrett's mucosa. Topoisomerase 2alpha protein expression was present in 50% of patients with cardiac mucosa. DAS-1 protein was expressed in cervical columnar mucosa but not in normal squamous esophagus mucosa. The cardiac mucosa stained weakly for COX-2 and ODC.

CONCLUSIONS

Cardiac mucosa can be acquired. Its expression profile is similar to cardiac mucosa and intestinal metaplasia found in Barrett's esophagus, and different from normal esophageal or gastric mucosa. The development of cardiac mucosa is likely to be related to reflux of acid into the remnant cervical esophagus as the first step in the development of Barrett's esophagus. These findings are applicable to the development of similar changes at the gastroesophageal junction.

Effects of concentrated ambient particles on normal and hypersecretory airways in rats

Epidemiological studies have reported that elevated levels of particulate air pollution in urban communities are associated with increases in attacks of asthma based on evidence from hospital admissions and emergency department visits. Principal pathologic features of chronic airway diseases, like asthma, are airway inflammation and mucous hypersecretion with excessive amounts of luminal mucus and increased numbers of mucus-secreting cells in regions of the respiratory tract that normally have few or no mucous cells (ie, mucous cell metaplasia). The overall goal of the present project was to understand the adverse effects of urban air fine particulate matter (PM2.5; < or = 2.5 pm in aerodynamic diameter)* on normal airways and airways compromised with airway inflammation and excess mucus. Our project was specifically designed to (1) examine the chemical and physical characteristics of PM2.5 and other airborne pollutants in the outdoor air of a local Detroit community with a high incidence of childhood asthma; (2) determine the effects of this community-based PM2.5 on the airway epithelium in normal rats and rats compromised with preexisting hypersecretory airway diseases (ie, animal models of human allergic airway disease--asthma and chronic bronchitis); and (3) identify the chemical or physical components of PM2.5 that are responsible for PM2.5 -induced airway inflammation and epithelial alterations in these animal models. Two animal models of airway disease were used to examine the effects of PM2.5 exposure on preexisting hypersecretory airways: neutrophilic airway inflammation induced by endotoxin challenge in F344 rats and eosinophilic airway inflammation induced by ovalbumin (OVA) challenge in BN rats. A mobile air monitoring and exposure laboratory equipped with inhalation exposure chambers for animal toxicology studies, air pollution monitors, and particulate collection devices was used in this investigation. The mobile laboratory was parked in a community in southwestern Detroit during the summer months when particulate air pollution is usually high (July and September 2000). We monitored the outdoor air pollution in this community daily, and exposed normal and compromised rats to concentrated PM2.5 from this local urban atmosphere. Rats in the inhalation studies were exposed for 1 day or for 4 or 5 consecutive days (10 hours/day) to either filtered air (controls) or concentrated ambient particles (CAPs) delivered by a Harvard ambient fine particle concentrator. Rats were killed 24 hours after the end of the exposure. Biochemical, morphometric, and molecular techniques were used to identify airway epithelial and inflammatory responses to CAPs. Lung lobes were also either intratracheally lavaged with saline to determine cellular composition and protein in bronchoalveolar lavage fluid (BALF) or removed for analysis by inductively coupled plasma-mass spectrometry (ICPMS) to detect retention of ambient PM2.5--derived trace elements. The Harvard concentrator effectively concentrated the fine ambient particles from this urban atmosphere (10-30 times) without significantly changing the major physicochemical features of the atmospheric particles. Daily CAPs mass concentrations during the 10-hour exposure period (0800-1800) in July ranged from 16 to 895 microg/m3 and in September ranged from 81 to 755 microg/m3. In general, chemical characteristics of ambient particles were conserved through the concentrator into the exposure chamber. Single or repeated exposures to CAPs did not cause adverse effects in the nasal or pulmonary airways of healthy F344 or BN rats. In addition, CAPs-related toxicity was not observed in F344 rats pretreated with bacterial endotoxin. Variable airway responses to CAPs exposure were observed in BN rats with preexisting allergic airway disease induced by OVA sensitization and challenge. Only OVA-challenged BN rats exposed to CAPs for 5 consecutive days in September 2000 had significant increases in airway mucosubstances and pulmonary inflammation compared to saline-challenged/air-exposed control rats. OVA-challenged BN rats that were repeatedly exposed to CAPs in July 2000 had only minor CAPs-related effects. In only the September 5-day exposure protocol, PM2.5 trace elements of anthropogenic origin (La, V, and S) were recovered from the lung tissues of CAPs-exposed rats. Recovery of these specific trace elements was greatest in rats with OVA-induced allergic airway disease. Additional laboratory experiments using intratracheal instillations of ambient PM2.5 samples were performed to identify bioactive agents in the CAPs to which rats had been exposed in the inhalation exposure component. Because the most pronounced effects of CAPs inhalation were found in BN rats with OVA-induced allergic airways exposed in September, we used ambient PM2.5 samples that were collected on 2 days during the September CAPs inhalation exposures to use for instillation. Ambient PM2.5 samples were collected, fractionated into soluble and insoluble species, and then compared with each other and with total PM2.5 for their effects in healthy BN rats and those with OVA-induced allergic airway disease. Intratracheal instillation of the insoluble fraction of PM2.5 caused mild neutrophilic inflammation in the lungs of healthy rats. However, total PM2.5 or the soluble or insoluble fractions instilled in rats with OVA-induced airway inflammation did not enhance the inflammation or the airway epithelial remodeling that was evident in some of the BN rats exposed to CAPs by inhalation. Therefore, the results from this instillation component did not suggest what fractions of the CAPs may have been responsible for enhancing OVA-induced airway mucosubstances and pulmonary inflammation observed in the inhalation exposure component. In summary, inhaled CAPs-related pulmonary alterations in the affected OVA-challenged rats appeared to be related to the chemical composition, rather than the mass concentration, to which the animals were exposed. Results of the trace element analysis in the lungs of CAPs-exposed BN rats exposed in September suggested that air particles derived from identified local combustion sources were preferentially retained in allergic airways. These results demonstrate that short-term exposures to CAPs from this southwestern Detroit community caused variable responses in laboratory rats and suggest that adverse biological responses to ambient PM2.5 may be associated more closely with local sources of particles and weather patterns than with particle mass.

Transitional Cell Metaplasia and Ectopic Prostatic Tissue in the Uterine Cervix and Vagina in a Patient with Adrenogenital Syndrome: Report of a Case Suggesting a Possible Role of Androgen in the Histogenesis

A case of extensive transitional cell metaplasia (TCM) and ectopic prostatic tissue was encountered in the uterine cervix and vagina of a 23-year-old woman with the adrenogenital syndrome. A previously described case of ectopic prostatic tissue in the cervix in a patient with female pseudohermaphroditism and our case suggest that prolonged androgen stimulation plays a role in the development of prostatic tissue. Similarly, the occurrence of TCM in the perimenopausal and postmenopausal periods when the ovaries secrete androgens, in female transsexuals treated with androgens, and in our patient with high endogenous androgen levels suggest that androgen has a major role in the histogenesis of TCM. Significantly decreased Ki-67 immunopositivity in TCM compared with the normal cervical mucosa of women in the reproductive age indicates that TCM is a mild form of epithelial atrophy, presumably caused by the neutralizing effect of androgens.

[A case of squamous metaplasia of the ureter]

This paper reports a 73-year-old man who developed ureteral squamous metaplasia. Preoperative drip infusion pyelography showed a ureteral tumor with a major axis measuring 2.5 cm, which had a smooth surface and a broad base. Computed tomography findings suggested that the lesion might be a submucous mesodermal tumor or inverted papillary transitional cell carcinoma. Therefore, retroperitoneal laparoscopic left nephroureterectomy was performed.

Human model of duodenogastro-oesophageal reflux in the development of Barrett's metaplasia (Br J Surg 2003; 90: 1120-1128)

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Bile duct cancer developing 21 years after choledochoduodenostomy

BACKGROUND

Cholangiocarcinoma in patients with choledochoenterostomy has been a rare condition with few cases reported in the literature written in English, and there have been few pathological descriptions of this disease. However, it has recently been documented as a late complication of choledochoenteric anastomosis, and has become a serious issue today since choledochoenterostomy and sphincteroplasty for benign biliary lesions were frequently resorted to in the 1970s and 1980s. The authors here present a case of a 67-year-old woman who developed a cholangiocarcinoma 21 years after choledochoduodenostomy.

METHODS

The patient underwent a curative resection of the tumor with a hepatopancreatoduodenectomy after a detailed preoperative assessment, including cholangiography and cholangioscopy.

RESULTS

Although this tumor has been reported to have a poor prognosis, a precise preoperative evaluation and aggressive surgery may contribute to better survival. Pathologically, the tumor originated in the bile duct mucosa of the choledochoduodenostomy, and was accompanied by intestinal and pyloric gland-like metaplasia.

CONCLUSION

These epithelial changes presumably induced by chronic inflammation due to the reflux of intestinal contents and bile stasis may be responsible for the carcinogenesis.

Trends in incidence and prevalence of specialized intestinal metaplasia, barrett's esophagus, and adenocarcinoma of the gastroesophageal junction

Most available information on the epidemiology of Barrettacute;s esophagus (BE) relates to patients with long segments (> 3 cm) of specialized intestinal metaplasia (SIM). Its prevalence is 3% in patients undergoing endoscopy for reflux symptoms and 1% in those undergoing endoscopy for any clinical indication. The latter prevalence is similar to the 1% found in autopsy series. A "silent majority" with BE remain unrecognized in the general population. BE is more common in men, and the prevalence rises with age. Recent endoscopic series document a rise in the diagnosis of endoscopically apparent short segments (< 3 cm) of BE (SSBE). The prevalence of SSBE in both unselected and reflux patients is 8% to 12%. Specialized intestinal metaplasia at the cardia, below a normal-appearing squamocolumnar junction, has been reported to vary from 6% to 25% in patients presenting for upper endoscopy. Unlike patients with long segment Barrett's esophagus (LSBE), the role of gastroesophageal reflux disease in the pathogenesis of SSBE and SIM of the cardia is controversial. Recent data suggest that the etiology of SIM of the cardia might be secondary to Helicobacter pylori infection, although the role of other environmental factors cannot be ruled out. The incidence of adenocarcinoma of the esophagus and esophagogastric juction (EGJ) has been increasing over the past 15 years in Western countries. Surgical series and population-based studies show that by 1994 adenocarcinomas of the esophagus accounted for half of all esophageal cancer among white men. LSBE and SSBE predispose to the development of adenocarcinoma of the esophagus and EGJ. The role of SIM of the cardia as a precursor lesion for EGJ adenocarcinoma is still unclear. The prevalences of dysplasia in LSBE and SSBE are around 6% and 8%, respectively. The incidence of adenocarcinoma in patients with LSBE is about 1 in 100 patient-years. Cancer risk for SSBE and SIM at the cardia is unknown. Smoking and obesity increase the risk for esophageal and EGJ adenocarcinomas.

Human model of duodenogastro-oesophageal reflux in the development of Barrett's metaplasia

BACKGROUND

Patients with an intrathoracic oesophagogastrostomy after subtotal oesophagectomy experience profound duodenogastro-oesophageal reflux (DGOR). This study investigated the degree of mucosal injury and histopathological changes in oesophageal squamous epithelium after subtotal oesophagectomy with gastric interposition in relation to the extent of postoperative DGOR.

METHODS

Serial endoscopic assessment and systematic biopsy at the oesophagogastric anastomosis was undertaken in 40 patients following curative radical subtotal oesophagectomy and reconstruction with a gastric conduit subjected to a pyloroplasty. Thirty patients subsequently underwent combined 24-h ambulatory pH and bilirubin monitoring.

RESULTS

Grade I-III oesophagitis was identified in 14 patients and oesophageal columnar epithelium in 19 patients. Biopsies from columnar regeneration revealed cardiac-type epithelium in ten patients and intestinal metaplasia in nine. Seven patients followed serially showed progression from cardiac-type epithelium to intestinal metaplasia. The incidence of Barrett's metaplasia was similar irrespective of the histological subtype of the resected tumour. Patients with oesophageal columnar epithelium had significantly higher acid (P = 0.015) and bilirubin (P = 0.011) reflux.

CONCLUSION

Severe DGOR occurs following subtotal oesophagectomy and provides an environment for the acquisition of Barrett's metaplasia via a sequence of cardiac epithelium and eventual intestinal metaplasia.

Pathogenesis of mucous cell metaplasia in a murine asthma model

Increased mucus production in asthma is an important cause of airflow obstruction during severe exacerbations. To better understand the changes in airway epithelium that lead to increased mucus production, ovalbumin-sensitized and -challenged mice were used. The phenotype of the epithelium was dramatically altered, resulting in increased numbers of mucous cells, predominantly in the proximal airways. However, the total numbers of epithelial cells per unit area of basement membrane did not change. A 75% decrease in Clara cells and a 25% decrease in ciliated cells were completely compensated for by an increase in mucous cells. Consequently, by day 22, 70% of the total epithelial cell population in the proximal airways was mucous cells. Electron microscopy illustrated that Clara cells were undergoing metaplasia to mucous cells. Conversely, epithelial proliferation, detected with 5-chloro-2-deoxyuridine immunohistochemistry, was most marked in the distal airways. Using ethidium homodimer cell labeling to evaluate necrosis and terminal dUTP nick-end labeling immunohistochemistry to evaluate apoptosis, this proliferation was accompanied by negligible cell death. In conclusion, epithelial cell death did not appear to be the stimulus driving epithelial proliferation and the increase in mucous cell numbers was primarily a result of Clara cell metaplasia.