The human oesophageal squamous epithelium exhibits a novel type of heat shock protein response

The human oesophageal epithelium is subject to damage from thermal stresses and low extracellular pH that can play a role in the cancer progression sequence, thus identifying a physiological model system that can be used to determine how stress responses control carcinogenesis. The classic heat shock protein HSP70 is not induced but rather is down-regulated after thermal injury to squamous epithelium ex vivo; this prompted a longer-term study to address the nature of the heat shock response in this cell type. An ex vivo epithelial culture system was subsequently used to identify three major proteins of 78, 70, and 58 kDa, whose steady-state levels are elevated after heat shock. Two of the three heat shock proteins were identified by mass spectrometric sequencing to be the calcium-calmodulin homologue transglutaminase-3 (78 kDa) and a recently cloned oesophageal-specific gene called C1orf10, which encodes a 53-kDa putative calcium binding protein we have named squamous epithelial heat shock protein 53 (SEP53). The 70-kDa heat shock protein (we have named SEP70) was not identifiable by mass spectrometry, but it was purified and studied immunochemically to demonstrate that it is distinct from HSP70 protein. Monoclonal antibodies to SEP70 protein were developed to indicate that: (a) SEP70 is induced by exposure of cultured cells to low pH or glucose starvation, under conditions where HSP70 protein was strikingly down-regulated; and (b) SEP70 protein exhibits variable expression in preneoplastic Barrett's epithelium under conditions where HSP70 protein is not expressed. These results indicate that human oesophageal squamous epithelium exhibits an atypical heat shock protein response, presumably due to the evolutionary adaptation of cells within this organ to survive in an unusual microenvironment exposed to chemical, thermal and acid reflux stresses.

Fluid phase endocytosis in oral epithelia: variation with site and effect of cancer

The structure of the oral mucosa has been extensively studied but its cell physiology has been less well characterised. This study aimed to show the range in variation in fluid phase endocytic capability in biopsies from different oral sites. Oral epithelial cells were obtained from both biopsies and single-cell suspensions obtained by brushing the oral cavity. Biopsies in organ culture and single cells in suspension were incubated with fluorescent microspheres of 0.02, 0.1 or 1.0 microm diameter. Endocytosis of fluorescent microspheres was quantitated by flow cytometry and visualised by confocal microscopy. Epithelial cells from all oral sites that were sampled internalised 0.02 microm and 0.1 microm but not 1.0 microm microspheres, with no significant differences observed between oral regions. Single cells from non-cancer patients endocytosed significantly more 0.02 microm microspheres than cells removed from patients with oral cancer. This model may be used to study integrated oral cell function both in health and disease.

The study of the process of fluid-phase endocytosis in cervical squamous cells using fluorescent microspheres

Physiological processes in cervical squamous epithelium have not been extensively studied. Perhaps understandably, most of the research has concentrated on the pathology of the cervix, in particular dysplasia and malignancy. Fluid-phase endocytosis is a physiological process which has been demonstrated to be important in understanding disease development at other squamous epithelial sites, e.g. oesophagus. In this study, we have demonstrated by a new methodology developed in our laboratory using fluorescent microspheres and flow cytometry that fluid-phase endocytosis occurs in cervical squamous cells. The process has been shown to be dose- and time-dependent. This novel approach provides a means to improve our understanding of the physiological functions of the cervix and may provide insight into the pathogenesis of cervical neoplastic and non-neoplastic disease.

Merkel cells in the human oesophagus

Merkel cells (MCs) are well recognized in the basal layers of the skin and oral mucosa, but this paper describes for the first time the presence of MCs in the human oesophagus. These cells are not identified in neonatal oesophagus, but are seen singly and in clusters in adult specimens. Application of stereological techniques shows that MCs are more numerous in the mid-oesophageal region. Cells expressing established markers of MCs have also been demonstrated in two out of six primary small cell carcinomas of the oesophagus. Further investigation of the role of MCs in oesophageal innervation and epithelial biology will be of interest.

Decision analysis of histamine H2-receptor antagonist maintenance therapy versus Helicobacter pylori eradication therapy: a randomised controlled trial in patients with continuing pain after duodenal ulcer

BACKGROUND

Much has been published on the efficacy and cost effectiveness of Helicobacter pylori eradication treatment as an alternative to histamine H2-receptor antagonist maintenance treatment in peptic ulcer disease. However, most studies have analysed and emphasised H. pylori eradication rates rather than management/control of symptoms and the associated cost savings. Although H. pylori eradication therapy is very successful in clearing the infection, dyspeptic symptoms may persist and management of these can be expensive.

OBJECTIVE

The aim of this study was to assess the cost implications in controlling symptoms using either H2-receptor antagonist maintenance therapy or H. pylori eradication therapy in patients with duodenal ulcer disease.

DESIGN

This was a non-blind, prospective, randomised, parallel-group study comparing maintenance H2-receptor antagonist treatment using ranitidine with H. pylori eradication therapy, with a 1-year follow-up.

SETTING

This was a study of outpatients from general practices in Dundee, Scotland, or the Ninewells Hospital, Dundee, gastroenterology clinic.

PATIENTS AND PARTICIPANTS

119 patients with confirmed duodenal ulcer, free from active ulceration at study entry but positive for H. pylori infection, who were receiving maintenance H2-receptor antagonist therapy.

INTERVENTIONS

Patients were randomised to receive either continuing maintenance therapy with ranitidine (initially 150 mg daily; 58 patients) or H. pylori eradication therapy using an omeprazole/amoxicillin/metronidazole regimen (or omeprazole/clarithromycin if allergic to penicillin).

MAIN OUTCOME MEASURES AND RESULTS

Overall, H. pylori eradication rates were 100% per protocol and 95.1% intention-to-treat. At completion of 1 year of follow-up, 12 of the 61 (19.7%) patients successfully eradicated of H. pylori were still dependent on acid suppression for symptom relief. H. pylori eradication treatment was the least-cost strategy in managing/controlling symptoms at 1 year (168 Pounds vs 210 Pounds per patient; 1996 values). However, over time, post-eradication treatment costs were greater than H2-receptor antagonist therapy costs. Any potential savings were directly related to the proportion of patients needing further treatment post-eradication, the cost of endoscopy and the urea breath test.

CONCLUSIONS

If dyspepsia persists long term, H. pylori eradication treatment may not be the least-cost option for patients with duodenal ulcer.

Ectopic expression of the minimal whiE polyketide synthase generates a library of aromatic polyketides of diverse sizes and shapes

The single recombinant expressing the Streptomyces coelicolor minimal whiE (spore pigment) polyketide synthase (PKS) is uniquely capable of generating a large array of well more than 30 polyketides, many of which, so far, are novel to this recombinant. The characterized polyketides represent a diverse set of molecules that differ in size (chain length) and shape (cyclization pattern). This combinatorial biosynthetic library is, by far, the largest and most complex of its kind described to date and indicates that the minimal whiE PKS does not independently control polyketide chain length nor dictate the first cyclization event. Rather, the minimal PKS enzyme complex must rely on the stabilizing effects of additional subunits (i.e., the cyclase whiE-ORFVI) to ensure that the chain reaches the full 24 carbons and cyclizes correctly. This dramatic loss of control implies that the growing polyketide chain does not remain enzyme bound, resulting in the spontaneous cyclization of the methyl terminus. Among the six characterized dodecaketides, four different first-ring cyclization regiochemistries are represented, including C7/C12, C8/C13, C10/C15, and C13/C15. The dodecaketide TW93h possesses a unique 2,4-dioxaadamantane ring system and represents a new structural class of polyketides with no related structures isolated from natural or engineered organisms, thus supporting the claim that engineered biosynthesis is capable of producing novel chemotypes.

Fluid phase endocytosis within buccal mucosal cells of alcohol misusers

The structure of the oral mucosa is now well characterised, although studies on oral epithelial cell function have received less attention. The aims of this study were to see whether endocytosis could be demonstrated in cells from oral smears and if so, to assess the effect of chronic high alcohol intake on such uptake. Buccal mucosal smears were collected from 135 patients (91 non- or social drinkers, and 44 patients with harmful alcohol use). Name, age, sex, and alcohol history (for alcohol problem patients) were recorded. Cell suspensions were incubated in a solution of bovine serum albumin (BSA)-coated fluorescently labelled latex microspheres (0.02 micron diameter) in Ham's F-10 culture medium for 1 h at 37 degrees C as a marker of fluid phase endocytosis. Uptake of microspheres was confirmed by confocal microscopy, and mean endocytosed fluorescence levels determined by flow cytometry. A repeat smear from 11 of the alcohol patients was taken 9-14 days later. Endocytosis was significantly reduced in both male (P < 0.01) and female (P < 0.01) alcohol problem patients compared to controls. Units of alcohol consumed and cigarettes smoked per day did not show a dose-response correlation with endocytosis in the alcohol problem patients. Apparent abstinence from alcohol had no further effect on endocytic uptake at days 9-14. This study shows that normal oral squamous cells removed as buccal smears readily endocytose fluorescent microspheres and that this capacity can be affected by alcohol. Chronic high alcohol intake would appear to down regulate endocytosis in buccal cells even up to 14 days of abstinence. This may have implications for the pathogenesis of oral mucosal disorders in long-term users.

H2-antagonist maintenance therapy versus Helicobacter pylori eradication in patients with chronic duodenal ulcer disease: a prospective study

BACKGROUND

Few outcome studies directly compare Helicobacter pylori eradication therapy with maintenance H2-antagonist therapy in duodenal ulcer disease.

AIM

To examine prospectively the efficacy of H. pylori eradication therapy with ranitidine maintenance therapy over 1 year in patients with confirmed chronic duodenal ulcer.

METHODS

One hundred and nineteen patients with active H. pylori infection were randomized to receive ranitidine, 150 mg/day initially (58 patients), or omeprazole, 40 mg/day, amoxycillin 2 g/day and metronidazole 1.2 g/day for 14 days, or omeprazole 40 mg/day and clarithromycin 1.5 g/day, for 14 days (if penicillin-allergic). Symptoms were assessed using the Gastrointestinal System Rating Scale (GSRS) and SF36 quality of life index.

RESULTS

13C urea breath testing confirmed overall treatment success in 100% of patients (58/58) per protocol and 95.1% (58/61) on an intention-to-treat basis. At 4 and 12 months there were no differences in any GSRS symptoms between treatment groups. SF36 analysis showed a perceived health improvement at 4 and 12 months in patients who received H. pylori eradication. However, despite successful H. pylori eradication, one-fifth of patients still required antisecretory therapy.

CONCLUSION

Following successful H. pylori eradication, chronic duodenal ulcer patients were at least as well symptomatically as when taking maintenance ranitidine. They perceived that their health had improved, but a subgroup was still acid-suppression dependent.

Microwaves and heat in aldehyde fixation: model experiments with bovine serum albumin

Most model experiments concerning tissue fixation have used low concentrations of fixatives and proteins. Here, high concentrations (up to 32%) of bovine serum albumin (BSA) were reacted with formaldehyde (1-20%) and glutaraldehyde (0.5-4%). Gels were formed between 16% BSA and 10-20% formaldehyde at room temperature, but not with percentages of formaldehyde lower than 4%. Microwave application or heating in a water bath to 50 degrees C gave a gel from 1 to 20% formaldehyde. Sixteen percent BSA also gave a gel with glutaraldehyde from 0.5 to 4%. Cone and plate viscometry showed rapidly increasing viscosity at 4% formaldehyde and 16% BSA at room temperature. At 50 degrees C, gels formed at a low concentration of formaldehyde. Tissue fixation in which the local concentrations of protein may be in excess of 30% is probably more complete than in vitro experiments in which low concentrations of reagents have been used to permit subsequent spectrometry. This was confirmed by polyacrylamide gel electrophoresis of liver.

Putative protein serine/threonine kinase genes are located in several positions on the chromosome of Streptomyces coelicolor A3(2)

Seven DNA fragments containing putative protein serine/threonine kinase genes were cloned from Streptomyces coelicolor A3(2) by hybridization with a 165-bp amplified polymerase chain reaction product of pkaB containing kinase subdomains VI, VII and VIII. Among them, the nucleotide sequences of three fragments containing subdomains VI, VII and VIII were identical, while those of one fragment were identical with that of afsK, another protein serine/threonine kinase gene. However, these kinase-like genes with very similar nucleotide sequences were distributed on the chromosome of S. coelicolor A3(2).

Biochemical and morphological correlations in human gallbladder with reference to membrane permeability

There is good evidence that gallbladder epithelium is permeable to a diverse range of molecules which move into the epithelial cell from the lumen or the basement membrane. Morphological investigations have shown both secretory mucous droplets, components of the endocytosis pathway together with evidence of a system allowing passage of molecules across the basement membrane. This indicates that the gallbladder epithelium may be influenced by molecules presented via the apical and basal membranes, complicating our understanding of gallbladder function, particularly in disease. Gallbladder disease increases the proteoglycan content of the basement membrane, but the implication of this in terms of permeability remains to be defined. Indeed, it remains unknown whether this precedes disease or is a manifestation of the disease process. The removal of water from hepatic bile by gallbladder involves two counter ion transport systems. Autoradiography shows that ion transport occurs into the lateral intracellular spaces but it remains unclear whether this leads to a hypertonic solution in these spaces causing an osmotically driven water absorption or if the process involves an osmotically linked isotonic secretion. These ion pumps are reversible, for water is absorbed during the interdigestive phase but fluid is secreted into the lumen during digestion or in the presence of disease. Appropriate neural stimulation can increase or decrease fluid absorption from the lumen while vasoactive intestinal peptide or secretin promote fluid secretion, probably mediated by prostaglandins leading to raised cyclic AMP acting at the cellular level. Immediate control may depend on intracellular Ca2+ which activates a calmodulin-protein kinase, phosphorylating the counter ion transporters to downregulate their activity. Failure of this regulatory process may explain the initial increase in bile concentrating potential seen in the development of gallstones although the mechanism of such failure remains unknown. More concentrated bile increases movement of biliary compounds into gallbladder epithelial cells which alter gallbladder function in a complex manner. Secondary bile acids are raised in gallstone disease and increase permeability of the gallbladder epithelium to molecules including cholesterol. This cholesterol absorbed from the lumen may have paramount importance to gallbladder function. Raised biliary cholesterol reduces gallbladder motility, possibly by increasing the amount of cholesterol in gallbladder muscle membranes and reducing contraction in response to cholecystokinin. However, increased secondary bile acids are also associated with an alteration in phospholipid acyl groups which may alter ion transport activity and/or cholesterol solubility within the micelle/vesicle. As the acyl groups show increased arachidonate levels the production of prostaglandins could be raised, although currently it is not known if this phospholipid arachidonate enters the epithelial cells. In addition, gallbladder inflammation is associated with raised phospholipase A2 activity, leading to formation of fatty acids and lysophospholipid which causes membrane damage. The fatty acids are likely to displace cholesterol from the micelle but may also act directly on the epithelium, possibly increasing prostaglandin production and thus stimulating mucin secretion. Increased mucin secretion is seen early in gallstone disease but the evidence presently available cannot determine if this is a causative factor.

Biochemical analysis of the stress protein response in human oesophageal epithelium

BACKGROUND

The oesophageal epithelium is exposed routinely to noxious agents in the environment, including gastric acid, thermal stress, and chemical toxins. These epithelial cells have presumably evolved effective protective mechanisms to withstand tissue damage and repair injured cells. Heat shock protein or stress protein responses play a central role in protecting distinct cell types from different types of injury.

AIM

To determine (i) whether biochemical analysis of stress protein responses in pinch biopsy specimens from human oesophageal epithelium is feasible; (ii) whether undue stresses are imposed on cells by the act of sample collection, thus precluding analysis of stress responses; and (iii) if amenable to experimentation, the type of heat shock protein (Hsp) response that operates in the human oesophageal epithelium.

METHODS

Tissue from the human oesophagus comprised predominantly of squamous epithelium was acquired within two hours of biopsy and subjected to an in vitro heat shock. Soluble tissue cell lysates derived from untreated or heat shocked samples were examined using denaturing polyacrylamide gel electrophoresis for changes in: (i) the pattern of general protein synthesis by labelling epithelial cells with 35S-methionine and (ii) the levels of soluble Hsp70 protein and related isoforms using immunochemical protein blots.

RESULTS

A single pinch biopsy specimen is sufficient to extract and analyse specific sets of polypeptides in the oesophageal epithelium. After ex vivo heat shock, a classic inhibition of general protein synthesis is observed and correlates with the increased synthesis of two major proteins of molecular weight of 60 and 70 kDa. Notably, cells from unheated controls exhibit a "stressed" biochemical state 22 hours after incubation at 37 degrees C, as shown by inhibition of general protein synthesis and increased synthesis of the 70 kDa protein. These data indicate that only freshly acquired specimens are suitable for studying stress responses ex vivo. No evidence was found that the two heat induced polypeptides are previously identified Hsp70 isoforms. In fact, heat shock results in a reduction in the steady state concentrations of Hsp70 protein in the oesophageal epithelium.

CONCLUSION

Systematic and highly controlled studies on protein biochemistry are possible on epithelial biopsy specimens from the human oesophagus. These technical innovations have permitted the discovery of a novel heat shock response operating in the oesophageal epithelium. Notably, two polypeptides were synthesised after heat shock that seem to differ from Hsp70 protein. In addition, the striking reduction in steady state concentrations of Hsp70 protein after heat shock suggests that oesophageal epithelium has evolved an atypical biochemical response to thermal stress.

Helicobacter pylori infection status in relation to antibiotic and non-steroidal prescribing in patients on maintenance treatment for chronic duodenal ulcer

It has been suggested that establishing Helicobacter pylori infection status is irrelevant prior to H. pylori eradication treatment in chronic duodenal ulcer, as virtually all may benefit from therapy.

OBJECTIVE

The aim of the present study was (i) to determine the prevalence of active H. pylori infection in patients with proven chronic duodenal ulcer on long-term H2-antagonist prophylactic treatment and whether knowledge of this would influence the use of eradication therapy and (ii) to assess other factors which might influence the clinical diagnosis or H. pylori status, such as non-steroidal and antibiotic use.

METHODS

One hundred and forty-five patients receiving long-term H2-antagonists for chronic duodenal ulcer were recruited. Their case records and a prescribing database were reviewed. Patients underwent endoscopy with biopsies for rapid urease test, histology and H. pylori culture. Serum was immunoblotted and an enzyme-linked immunosorbent assay for H. pylori was performed.

RESULTS

Of the 145 patients, 128 (88%) were H. pylori biopsy positive. Twelve of the 17 H. pylori biopsy-negative patients had anti-H. pylori immunoglobulin G (IgG) antibodies and 10 of the 17 H. pylori-negative patients had previously received antibiotics for other indications. Nine patients were exposed to non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) and one had additional aspirin exposure.

CONCLUSION

Only 11.7% of patients on maintenance treatment for chronic duodenal ulcer had no current infection with H. pylori, although more than 70% of these had serological evidence of previous infection. Confirmation of active infection may be indicated where there is a history of NSAID or antibiotic exposure and may result in more precise targeting of eradication therapy, thus avoiding unnecessary and potentially hazardous treatment.

Carbonic anhydrase isoenzymes I, II, III, and IV are present in human esophageal epithelium

Carbonic anhydrase (CA) isoenzymes have been widely studied in the gastrointestinal tract, where they mediate membrane transport events and pH regulation. However, the esophagus has generally received scant attention. In an immunohistochemical study confirmed by Western blotting, we have detected for CA isoenzymes (CAI, II, III, and IV) in the epithelium of human esophagus. Isoenzymes I, III, and sometimes IV (< 10%) were present in the cytoplasm of basal cells and II and IV in the cytoplasm and cell surface membranes, respectively, of suprabasal cells (prickle cells). The localization of CAIV to the plasma membranes was confirmed by electron microscopic immunocytochemistry. CA was effectively divided at the basal-suprabasal interface between low-activity CAI and III (basal) and high-activity CAII and IV (suprabasal). Carbonic anhydrase in esophageal epithelial cells may have several functions: elimination of CO2 and metabolites, participation in membrane transport events during active cell growth, and pH regulation as a protective mechanism against acidic gastric reflux.

An immunocytochemical study of the carbonic anhydrase I isoenzyme in human oral Merkel cells

Merkel cells in human buccal mucosa and hard palate possess the carbonic anhydrase I isoenzyme (CAI). CAI colocalized immunocytochemically with a range of Merkel cell cytokeratins, namely CK 7, 8, 18, 19 and 20. No other cells in the oral epithelium were immunoreactive for the CAI antibody. The presence of the enzyme may be related to the function of sensory receptors that produce a sustained response to a maintained mechanical stimulus.

The effects of mercaptoethanol-formaldehyde on tissue fixation and protein retention

The study compared the effects of mercaptoethanol-formaldehyde and formaldehyde alone, on tissue fixation and protein retention in human and mouse tissues. Shrinkage of tissues and the penetration rate of the fixatives were assessed. The cross-linking ability of the fixatives was determined by viscometry, sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and spectrophotometry, using bovine serum albumin and human haemoglobin. Tissues fixed in buffered 0.0025% mercaptoethanol-4% formaldehyde showed good nuclear and cytoplasmic detail, better than those fixed in buffered 4% formaldehyde. There was no significant difference in shrinkage. A mixture of 0.0025% mercaptoethanol-4% formaldehyde penetrated faster into adult liver than 4% formaldehyde. The mean penetration rate (+/-SE) or coefficient of diffusibility of 0.0025% mercaptoethanol-4% formaldehyde into adult liver was 1.32 +/- 0.01 and that of 4% formaldehyde was 1.12 +/- 0.06 (p < 0.04). Both fixatives diffused more rapidly into mouse liver than into human liver. The cross-linking ability of mercaptoethanol-formaldehyde depends on the concentration of the fixative and the time of fixation. Bovine serum albumin (15%) and 0.1% mercaptoethanol alone formed a gel, whilst electrophoresis showed monomers in the supernatant. Mercaptoethanol (0.1%) also rapidly decreased the absorption at 420 nm, suggesting denaturation. It seems that mercaptoethanol increases the number of thiol groups available to form cross-links with formaldehyde. This study demonstrated that mercaptoethanol-formaldehyde fixed and cross-linked tissues better than formaldehyde at 3 h and 4 h, but not at 1 h and 2 h. The most effective concentration of mercaptoethanol for tissue fixation in 4% formaldehyde is 0.0025%.

Endocytosis of fluorescent microspheres by human oesophageal epithelial cells: comparison between normal and inflamed tissue

This paper examines the presence and characteristics of endocytosis by oesophageal epithelial cells. Biopsy specimens from normal and inflamed oesophagus were incubated in organ culture with fluorescent microspheres (0.1 and 0.01 microns diameter). These markers were taken into early endosomes and the lysosomes of both the smaller differentiating prickle cells and the larger mature squamous cells. Confocal and electron microscopy showed that markers passed to the early endosomes and the lysosomes by endocytosis. The process was energy dependent. Larger, 1 micron microspheres adhered to the epithelial cells but were not phagocytosed. Disaggregated cells were analysed by flow cytometry. Microspheres were endocytosed in proportion to the concentration in the culture medium in a dose dependent manner. Cells from inflamed oesophagus were significantly smaller (p = 0.013) and took up significantly more microspheres than cells from normal biopsy specimens (p = 0.015). In conclusion, endocytosis occurs in oesophageal epithelial cells and is increased in inflammation.

Carbonic anhydrase is present in human oesophageal epithelium and submucosal glands

Carbonic anhydrase (EC 4.2.1.1) activity was investigated in normal human oesophageal mucosa using the Hansson and Ridderstråle catalytic cobalt methods. The enzyme was detected in the cell membranes and nuclei and, to a lesser extent, in the cytoplasm of the epithelial cells of the mucosa giving a 'chicken wire' appearance. Activity decreased towards the lumen. Other stratified squamous epithelia--buccal mucosa, ectocervix and skin--gave a similar pattern. Acinar cells of oesophageal submucosal glands also exhibited activity for the enzyme, but the ducts did not. The formation of reaction product was prevented by acetazolamide and ethoxzolamide and by the omission of bicarbonate frm the substrate medium. Carbonic anhydrase in oesophageal squamous epithelium may be involved in the control of intra- and extracellular pH, while that in the glands is more likely to be concerned with bicarbonate secretion.

A histochemical study of carbonic anhydrase in the plasma membranes of human oral epithelial cells

Carbonic anhydrase (EC 4.2.1.1) was detected histochemically from the following regions in patients of various ages (14-84 yr): buccal mucosa, buccal flap, hard palate and tongue. The enzyme was principally located in the cell membranes but was also present in nuclei. There was a gradation in activity from basal (strong) to superficial cells (weak/negative). The carbonic anhydrase inhibitors ethoxyzolamide and acetazolamide abolished activity at 0.001 mM, but were ineffective, even at 1.2 mM, against a reaction associated with the granules of the stratum granulosum. No activity was detected in the absence of bicarbonate from the substrate.

A comparison of membrane enzymes of human and pig oesophagus; the pig oesophagus is a good model for studies of the gullet in man

The distribution and relative catalytic activities of five plasma membrane enzymes (alkaline phosphatase, dipeptidyl peptidase IV, gamma-glutamyl transpeptidase, microsomal alanyl aminopeptidase and glutamyl aminopeptidase) were examined in human and pig oesophagus. In both species, alkaline phosphatase activity occurred in basal and suprabasal cells of the epithelium and in capillaries. Stromal cells in the human submucosa were particularly reactive. Dipeptidyl peptidase IV was present in blood vessels and capillaries in man and pig and in submucous glands in the pig. The enzyme was also present in both species in the lamina propria cells immediately adjacent to the epithelial basal lamina. In the human, gamma-glutamyl transpeptidase occurred in the epithelial basal cells and in isolated basal and lower prickle cells in the pig. Stromal cells in the human submucosa were strongly reactive and capillaries in the muscularis propria in both species moderately active. Microsomal alanyl aminopeptidase was detected in lamina propria cells adjacent to the epithelial basal cell layer in man and pig and at the apices of mucous cells in pig submucous glands. Weak glutamyl aminopeptidase activity was confined to capillaries in both species. The findings of this study, along with the ready availability of pig oesophagus, suggest that the pig may be a suitable model for studies of the gullet in man.

Oesophageal defence mechanisms

Various defence mechanisms are found in the oesophagus which can be elicited by reflux damage. Premucosal defence includes bicarbonate ions and epidermal growth factor (EGF) secreted by salivary and oesophageal glands. The mucosa can respond by increasing epithelial cell turnover and upregulating EGF receptor and endocytosis. The intercellular barrier can be increased by the contents of membrane-coating granules. Local pH can be regulated by carbonic anhydrase. The whole viscus can exhibit peristalsis to effect a mechanical clearance of the refluxed gastric and duodenal material.

Regulation of cell number in the mammalian gastrointestinal tract: the importance of apoptosis

The regulation of cell number in adult tissues is determined by the balance of cell production and cell loss. In the gastrointestinal tract, where there are well defined zones of proliferation and migration of both epithelial cells and associated fibroblasts, it is widely held that cell loss occurs by shedding into the gut lumen. Since the evidence for this is not compelling, we investigated the distribution and amount of apoptosis in the normal mammalian gut. In the stomach, small intestine and colon of rodents and man, there is a small number of apoptotic bodies in the epithelium and in the immediate sub-epithelial connective tissue. Engulfment by adjacent epithelial cells and sub-epithelial macrophages accounts for the removal of apoptotic bodies. Apoptotic bodies are not randomly distributed but are found towards the distal end of the known cellular migration routes of both epithelial and mesenchymal cells. Furthermore, consideration of the absolute numbers of apoptotic bodies, their rapid clearance and the dimensions of the small intestinal villi and colonic crypts indicates that the cell loss in the normal murine intestine can largely be explained on the basis of the observed apoptosis. Despite being inconspicuous in histological material, apoptosis probably accounts for the bulk of cell loss in the gut and is a central feature of the regulation of cell number in adult tissues.

Cell adhesion molecules in oesophageal epithelium

The distribution of a range of integrins, E-cadherin, and carcino-embryonic antigen (CEA) like molecules in normal human oesophageal epithelium was investigated immunohistochemically on frozen sections of endoscopic biopsy specimens. The integrin subunits alpha 2, alpha 3, alpha 6, alpha v, beta 1, and beta 5 were expressed throughout the epithelium. There was strong expression of alpha 2, alpha 3, and beta 1 subunits in the basal cell layer and for all the subunits studied the intensity of the staining decreased as cells moved towards the lumen. The heterodimer alpha v beta 3 was expressed weakly in the basal aspect of the basal cell layer only. The CEA molecules were not present in the basal cells layer but there was weak expression in the prickle cell layer and strong positivity in the mature functional layer. E-cadherin was found throughout the epithelium but was weakly expressed at the basal aspect of the basal cells layer and showed strong positivity in the prickle cell and squamous cell layers. These results indicate that cell-cell (E-cadherin, CEA) and cell-matrix (integrins) adhesion molecules show a well defined spatial pattern of immunoreactivity in the oesophageal mucosa and may play a part in the maintenance of normal tissue architecture and physiological homeostasis.

The prognostic significance of the accumulation of p53 tumour-suppressor gene protein in gastric adenocarcinoma

We have studied the expression of p53 in 206 patients with gastric adenocarcinomas. A standard immunohistochemical technique employing the CM-1 anti-p53 polyclonal antibody was applied to the routinely fixed and paraffin-embedded material from these tumours; overexpression of p53 was defined as positive nuclear staining: 46% (94/206) of gastric carcinomas expressed high levels of p53. There was no significant correlation between p53 positivity and the tumour grade, growth pattern, the Lauren type or lymph node metastases. Correlation with disease stage was only marginally significant (P = 0.05). Life table analysis revealed a highly significant association between p53 expression and survival (P = 0.0062), the odds ratio of death being 1.89 (95% confidence interval 1.33-2.69). The overall 5-year survival of patients with p53-positive tumours was 3% compared with 16% for those with p53-negative tumours (median survival time being 5.6 and 11.4 months respectively). These data suggest that overexpression of the p53 oncoprotein is an independent marker of shortened survival in gastric cancer patients.

Secretory and absorptive activity of oesophageal epithelium: evidence of circulating mucosubstances

The space between the oesophageal basal and prickle epithelial cells appears empty by standard ultrastructural preparative techniques. Fixation of human oesophageal biopsies with a variety of agents, including tannic acid, glutaraldehyde-lysine, cetylpyridinium chloride and Ruthenium Red shows that this space is filled with mucosubstances, some free, some attached to the cells as a glycocalyx. There is evidence that this material is secreted constitutively by the basal and prickle cells. This secretion may be changed or blocked by incubating oesophageal biopsies in the presence of colchicine or dinitrophenol. Incubation at 16 degrees C has the same effect. Absorption from the intercellular space may be followed using the fluid phase marker, horseradish peroxidase. Early endosomes may also be shown by their acid phosphatase activity. Incubation of biopsies at 20-22 degrees C allows early endosomes to accumulate material, but not pass it on the late endosomes.

Enzyme-linked immunosorbent assay for p53 in gastrointestinal malignancy: comparison with immunohistochemistry

Mutations in the p53 nuclear oncogene occur frequently in a wide spectrum of human malignancies and the mutant protein may prove to be a useful diagnostic or prognostic marker. It can be detected in fixed tissues by immunohistochemistry, but the type of fixative and conditions of fixation used can introduce variability. For routine clinical use, a method of analysis which is more easily standardized would, therefore, be of benefit. A two-site enzyme-linked immunosorbent assay (ELISA) was used to measure the level of p53 protein in soluble extracts from 20 gastrointestinal cancers (11 colonic, nine gastric). Immunohistochemistry was also performed on the paraffin-embedded sections of these tumours and the results of the two assays were compared. ELISA detected p53 at various levels in 10 cases, all of which were also positive by immunohistochemistry. Of the other 10, eight were immunohistochemically negative but two were positive. When the immunohistochemically positive specimens were ranked by scoring the degree of staining, there was a highly significant correlation with the quantitative ELISA results. Our study shows that the ELISA is sensitive and highly specific. It offers an alternative and simple method of assessing the p53 status in human tissues.

Monoclonal antibodies to cytoskeletal proteins: an immunohistochemical investigation of human colon cancer

Monoclonal antibodies raised to a number of microfilament-associated proteins were shown to recognize the appropriate proteins in extracts from human colon tissue. They were then used in an immunohistochemical study of normal colonic mucosa, adenomas, and adenocarcinomas. A strong reaction was seen in stromal cells within the tumours (both adenomas and adenocarcinomas) when frozen sections were stained with antibodies to filamin and caldesmon. In addition, a similar reaction was seen in the adenocarcinomas when stained with antibodies to talin and gelsolin. We believe that immunohistochemical staining with these antibodies reveals a tumour-induced process in the surrounding cells, possibly related to a host response to tumours.

Expression of p53 protein in normal, dysplastic, and malignant gastric mucosa: an immunohistochemical study

Mutations in the p53 nuclear oncogene are the most frequent genetic abnormalities encountered in human malignancies. Using the polyclonal antibody CM-1, we have examined the expression of the p53 oncoprotein immunohistochemically in archival material of normal, dysplastic, and malignant gastric mucosa. Abnormal expression of this protein was not observed in biopsies of normal gastric tissue (n = 30) but was detected in 22 of the 36 gastric cancers analysed (61 per cent). Nuclear staining was diffuse in 15 of the positive cancer cases, the remaining seven showing a more varied heterogeneous staining pattern. Abnormal p53 protein was not detected in mild (n = 14) or moderate (n = 16) gastric dysplasia but was present in 3 out of 15 severe dysplasia cases. The results suggest that expression of the p53 oncoprotein is a common finding in gastric cancer and occurs as a late event in the malignant transformation process.

Departmental audit in histopathology

Audit is now part of any laboratory service. Histopathology is no exception, and we have set up a system which allows us to review 4% of our specimens. These specimens are identified using a random number generator and reviewed by a consultant pathologist. Both slides and wet specimens are reviewed and graded according to a set scheme. The results from the first year of operation (1990) show a high rate of accuracy with no serious diagnostic disagreements between the auditor and the reporting pathologist. However, some errors which we would wish to prevent were detected and the audit has allowed us to take corrective measures. In our opinion, this form of audit is useful and necessary to maintain good clinical practice. The cost is considerable--histopathology is by its nature labour intensive. Recognition of this fact by health boards is essential if such systems are to continue.

Hyperplastic polyps: a cell lineage which both synthesizes and secretes trefoil-peptides and has phenotypic similarity with the ulcer-associated cell lineage

Hyperplastic polyps are common benign lesions of uncertain histogenesis, which occur in the colon in populations at risk for colorectal carcinoma. They contain neutral/MUC1 gene-related mucin which in turn is closely associated with the trefoil-peptide pS2, a major component of the ulcer-associated cell lineage, previously termed pseudopyloric metaplasia. We have examined 17 hyperplastic polyps for expression of the trefoil-peptides pS2 and human spasmolytic polypeptide by in situ hybridization and immunohistochemistry, as well as by using antisera to epidermal growth factor/urogastrone and its receptor and to epitopes of the product of the MUC1 gene to characterize any further similarity between these lesions and the ulcer-associated cell lineage and thus help elucidate the nature of the lesions. Our investigations show both human spasmolytic polypeptide and pS2 messenger RNA within the polyps, whereas only pS2 peptide could be demonstrated immunohistochemically. Epidermal growth factor/urogastrone, its receptor, and antisera to the MUC1 gene also showed widespread staining of these polyps. We suggest that hyperplastic polyps are formed of a lineage that both synthesizes and secretes trefoil-peptides and the MUC1 mucin and that hyperplastic polyps may be related to the phenotypically similar ulceration-associated cell lineage.

Increased expression of epidermal growth factor receptors in Barrett's esophagus associated with alkaline reflux: a putative model for carcinogenesis

A 49-yr-old male was reviewed who had a 10-yr history of reflux esophagitis. He presented initially with frequent heartburn of moderate severity and, on subsequent endoscopy, was noted to have erosive esophagitis and, at that time, a high maximal gastric acid output. During the next 5 yr, his symptoms and acid output diminished. Eight years after presentation, he was noted to have developed a small area of Barrett's metaplasia, without dysplastic change. Ten years after the initial presentation he was completely asymptomatic, despite having extensive Barrett's metaplasia, now with high grade dysplasia. As a result, he was referred for esophagogastrectomy. At the time of surgery, he had alkaline reflux, with antacid gastric contents and, subsequently, hypochlorhydria was proven by a pentagastrin test. A second individual (male, 46 yr) who presented initially with reflux symptoms and gastric-type metaplasia, underwent gastric secretory studies that revealed a peak acid output of 16 mmol/L in 1986. During the period 1989 to 1991, his symptoms progressed despite H2 antagonist therapy. In this regard he was reinvestigated, and his peak acid output in 1991 was 0 mmol/L, and subsequent esophageal biopsies demonstrated intestinal metaplasia in four of six biopsies (two biopsies had high-grade dysplasia; the two others had gastric-type metaplasia). He has refused esophageal resection, and is being reviewed regularly at the endoscopy clinic. Flow cytometric analysis of the esophagus in both individuals revealed expression of epidermal growth factor receptor which was increased in the areas of high grade dysplasia, compared with Barrett's mucosa without dysplasia or normal cardiac mucosa. We conclude that alkaline reflux may accelerate the development of Barrett's esophagus (and intestinal type metaplasia) in patients with gastroesophageal reflux disease. The increased expressed of epidermal growth factor receptors in Barrett's mucosa with dysplasia compared with Barrett's mucosa without dysplasia may reflect the higher malignant potential of the former mucosa.

Expression of epidermal growth factor, transforming growth factor alpha and their receptor in gastro-oesophageal diseases

This article is a review of aspects of the expression of the regulatory peptides; epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and their receptor (EGF-R) in the epithelium of the human oesophagus and stomach in health and disease. It has become clear that TGF-alpha has increased expression in metaplastic, dysplastic and neoplastic tissue of the oesophagus compared with normal mucosa. The degree of abnormal expression becomes more marked as dysplasia increases. TGF-alpha expression is also increased in gastric neoplasias. EGF has a different pattern of expression, being decreased in oesophagitis and increased in gastritis. Although EGF is present in Barrett's oesophagitis, the expression of EGF does not discriminate between dysplastic and neoplastic epithelium. EGF-R is normally expressed on all gastro-intestinal epithelia, but its expression is increased in Barrett's epithelium, as well as in adenocarcinomas of the oesophagus and the stomach. The two peptides bind to their receptors on the mucosal cell membranes, and the co-expression of peptide and receptor is positively associated with varying degrees of cellular proliferation. The density of receptor expression may modulate the proliferative stimulus, leading to either mitogenic (regulated) or oncogenic (unregulated) growth.

Adverse influence of fibrin sealant on the healing of high-risk sutured colonic anastomoses

The effect of fibrin glue sealing on sutured colonic anastomoses was studied using a 'high-risk' colon anastomosis model in the rat. Animals (n = 104) were randomized to have their sutured anastomosis sealed with fibrin glue or left untreated. They were assessed clinically until they were killed on the fourth day after surgery when contrast radiology, detailed post-mortem examination, anastomotic bursting pressure (ABP) and assessment of adhesion formation were performed. The clinical outcome was worse in the glued group (toxic or death from sepsis: 18 versus seven in the non-glued group; P = 0.0354), which also showed a significantly higher moderate to major leak rate (17 versus two in the non-glued group; P = 0.0009). The median ABP was significantly higher in the glued anastomosis group (96 versus 68 cmH2O in the non-glued group; P = 0.0367). Excessive perianastomotic adhesion formation was significantly greater in the glued group. Microscopic examination showed an extremely intense inflammatory reaction in the glued anastomoses compared with that in the untreated group. These results indicate that sealing of a sutured anastomosis with fibrin glue containing an antiproteinase impairs healing the of anastomotic wound, probably by resisting the ingrowth of vascular granulation tissue during the early stages of repair.

Epidermal growth factor in the oesophagus

Epidermal growth factor (EGF) has been implicated in mitogenesis and oncogenesis in the gastrointestinal tract. To determine the role of EGF in oesophageal disease, its quantity and distribution in the oesophageal mucosa of control subjects and patients with oesophageal disease were studied. Oesophageal biopsy specimens, taken 20-40 cm from the incisors in 72 patients, were graded histologically and adjacent specimens were taken for immunohistochemical analysis of the distribution of EGF. In patients with Barrett's columnar lined oesophagus, specimens were also taken from the gastric cardia for comparison. Twenty two biopsy specimens showed oesophagitis, 20 Barrett's mucosa, and 30 were histologically normal. EGF was found in the capillary endothelium of the normal oesophageal papillae and basal mucosa. Significantly more EGF positive papillae were found in the normal mucosa (81%) than in the inflamed mucosa (42%) (p < 0.001). The 20 patients with Barrett's mucosa showed abnormal expression of EGF in 25% of the isthmus and superficial epithelial cells. This study has shown that EGF is found only in the endothelial cells of the capillaries of the normal oesophageal mucosa and that the peptide is detectable significantly less frequently than normal in the inflamed oesophageal mucosa. EGF is also abnormally present, in large quantities, in the cytoplasm of the epithelial cells of Barrett's mucosa compared with gastric mucosa.

Oncogenes and onco-suppressor gene in adenocarcinoma of the oesophagus

While the activation of the proto-oncogenes has been implicated in the development and progression of cancer of many tissues, the role of oncogenes in the development of oesophageal adenocarcinoma has not been defined. Fifteen patients who had undergone resection for oesophageal adenocarcinoma and 15 who had undergone oesophagectomy or biopsy for Barrett's oesophagus were studied. The latter patients also had adjacent normal gastric mucosa biopsied for comparison with the metaplastic oesophageal mucosa. The mucosal samples were snap frozen and subsequently stained with monoclonal antibodies to the following oncogene associated proteins; c-erbB2 (neu and CE-1) (external domain), c-erbB2 (NCL-CB11) (internal domain), c-src, c-ras, c-myc, c-fos, c-jun, and the onco-suppressor gene--p53. All tumours were well or moderately differentiated adenocarcinomas arising from the lower third of the oesophagus. Eleven specimens showed strong membraneous staining with both c-erbB2 (neu) and c-erbB2 (CBL-CB11). Seven specimens showed strong nuclear staining with p53 onco-suppressor gene. Three specimens were positive for c-ras and c-src, and two were positive for c-jun. In Barrett's epithelium, nine specimens were positive for c-erbB2 (neu and CB11), three were positive for c-src, two were positive for c-ras and c-jun, and one was positive for c-fos. Two of the gastric mucosal biopsy specimens expressed c-erbB2 weakly but no other oncogenes were found. The frequency of positive staining for c-erbB2 is very high, compared with the expression of these genes in other tumours. It is also concluded that errors in the onco-suppressor gene p53, and especially in the external and internal domains of c-erbB2, which is also often expressed in Barrett's mucosa, may be implicated in the development of adenocarcinoma of the oesophagus.

Flow cytometry of oesophageal mucosal biopsies; epidermal growth factor receptor, and CD15

Flow cytometry may be used to examine the properties of single or isolated cells. We have shown that it is possible to disaggregate and label oesophageal epithelial cells for two surface markers, CD15 and epidermal growth factor receptor. We have previously demonstrated these markers in oesophageal squamous cells using immunoperoxidase techniques. These labelled disaggregated cells could then be measured by flow cytometry.

Proliferating cell nuclear antigen in oesophageal diseases; correlation with transforming growth factor alpha expression

This study was designed to correlate mucosal proliferation in Barrett's oesophagus with expression of a growth promoting peptide, transforming growth factor alpha (TGF alpha). Oesophageal mucosa was studied from 50 patients with oesophageal disease who had been treated by oesophagectomy. Histological analysis showed a range of oesophageal pathology - 18 patients had gastric type Barrett's mucosa, 18 had intestinal type Barrett's mucosa, and 14 had oesophageal adenocarcinomas. Sections were stained immunohistochemically for proliferating cell nuclear antigen (PCNA) (an index of cellular proliferation) and TGF alpha. PCNA immunostaining was seen mainly in the basal cells of the neck/foveolar epithelial compartment of the glands in Barrett's oesophagus. However, in mucosa with high grade dysplasia, the proliferative compartment extended upwards into the superficial layers of the glands. At least 2000 cells were counted in each patient to determine the proportion with PCNA immunoreactivity (PCNA labelling index). The labelling index was highest in adenocarcinoma (25%) and in Barrett's intestinal type mucosa with high grade dysplasia (26%) compared with intestinal type mucosa with no significant dysplasia (20%) and Barrett's gastric type mucosa (12%). There was a significant positive correlation between PCNA labelling indices and TGF alpha expression in Barrett's mucosa (p less than 0.01). In glands showing high grade dysplasia, TGF alpha immunoreactivity was seen in the same regions of the glands as PCNA immunoreactivity, indicating the possibility of involvement of TGF alpha in (pre) neoplastic proliferation in Barrett's oesophagus.

Growth regulatory peptides in gastric mucosa

1. Epidermal growth factor and the related peptide transforming growth factor alpha have been implicated in the stimulation of gastric mucosal proliferation. We assessed the immunohistochemical distribution of these peptides and their receptor, epidermal growth factor receptor, in mucosa from the antrum and body of the stomach from 28 patients. Twenty-three of the 56 biopsies were histologically normal (12 antrum and 11 body), whereas the other 33 showed varying degrees of inflammation. 2. Epidermal growth factor, transforming growth factor alpha and epidermal growth factor receptor had maximal density of distribution on the apical surfaces of the superficial epithelial cells, but were also expressed to a lesser extent on neck and body cells of the glandular tissue (P less than 0.05). We also demonstrated that epidermal growth factor expression was greater in the epithelial cells of inflamed mucosa than in those of normal mucosa (P less than 0.05). 3. We assessed mucosal proliferation by the Ki-67 labelling index. Ki-67-positive cells were found predominantly in the neck area of the glands and were more frequent in glandular antral tissue than in body glandular tissue (P less than 0.05). Expression of epidermal growth factor receptor in the neck and isthmus cells had a significant correlation with the Ki-67 labelling index (P less than 0.05). 4. We conclude that epidermal growth factor and epidermal growth factor receptor may be important in the adaptation of gastric mucosa to inflammation.

Membranous expression of carcinoembryonic antigen (CEA) in the normal cervical squamous mucosa

Using a panel of polyclonal and monoclonal antibodies to CEA-related antigens in paraffin-processed cervical biopsies, CEA and NCA expression has been demonstrated on the cell membrane of normal mature cervical squames. Cytofluorimetry of disaggregated cervical squames confirmed membranous expression and immunogold labelling of ultrathin cryostat sections localized CEA to the glycocalyx and to within cytoplasmic membrane-bound vesicles of mature squames. Immunoblotting of cervical tissue showed that most of the CEA reactivity was expressed as a glycoprotein of molecular weight around 180 k, probably CEA itself. Localization of the CEA to the cell membrane of mature cervical squames suggests a key role for these antigens in maintaining the integrity of the squamous mucosa, through the putative function of an adhesion molecule.

Epidermal growth factor receptors in the oesophagus

The quantity and distribution of epidermal growth factor receptors (EGF-R) in oesophageal mucosa was studied in the oesophagus in order to determine its role in oesophageal disease. Fifty five biopsies were taken from different levels of the oesophagus in 25 consecutive patients undergoing endoscopy. Another group of eight patients with histologically proven Barrett's oesophagitis had a biopsy taken from the area of columnar lined oesophagus. A peripheral, membranous pattern was seen predominantly confined to the basal and immediately suprabasal cells in all of the first group of patients. In the superficial cells a few granular cytoplasmic structures were positive. All patients with Barrett's oesophagitis showed EGF-R staining of the surface epithelium. A computerised planimeter was used to determine the proportion of stained areas of squamous cells which were expressed as a percentage of the total area of squamous cells. The difference in the area of cells stained for EGF-R between normal and inflamed oesophageal mucosa (29.5% and 43.1% respectively) was significant (p less than 0.001).