The localization of bullous pemphigoid antigen 180 (BP180) in hemidesmosomes is mediated by its cytoplasmic domain and seems to be regulated by the beta4 integrin subunit

Bullous pemphigoid antigen 180 (BP180) is a component of hemidesmosomes, i.e., cell-substrate adhesion complexes. To determine the function of specific sequences of BP180 to its incorporation in hemidesmosomes, we have transfected 804G cells with cDNA-constructs encoding wild-type and deletion mutant forms of human BP180. The results show that the cytoplasmic domain of BP180 contains sufficient information for the recruitment of the protein into hemidesmosomes because removal of the extracellular and transmembrane domains does not abolish targeting. Expression of chimeric proteins, which consist of the membrane targeting sequence of K-Ras fused to the cytoplasmic domain of BP180 with increasing internal deletions or lacking the NH2 terminus, indicates that the localization of BP180 in hemidesmosomes is mediated by a segment that spans 265 amino acids. This segment comprises two important regions located within the central part and at the NH2 terminus of the cytoplasmic domain of BP180. To investigate the effect of the alpha6beta4 integrin on the subcellular distribution of BP180, we have transfected COS-7 cells, which lack alpha6beta4 and BP180, with cDNAs for BP180 as well as for human alpha6A and beta4. We provide evidence that a mutant form of BP180 lacking the collagenous extracellular domain as well as a chimeric protein, which contains the entire cytoplasmic domain of BP180, are colocalized with alpha6beta4. In contrast, when cells were transfected with cDNAs for alpha6A and mutant forms of beta4, either lacking the cytoplasmic COOH-terminal half or carrying phenylalanine substitutions in the tyrosine activation motif of the cytoplasmic domain, the recombinant BP180 molecules were mostly not colocalized with alpha6beta4, but remained diffusely distributed at the cell surface. Moreover, in cells transfected with cDNAs for alpha6A and a beta4/beta1 chimera, in which the cytoplasmic domain of beta4 was replaced by that of the beta1 integrin subunit, BP180 was not colocalized with the alpha6beta4/beta1 chimera in focal adhesions, but remained again diffusely distributed. These results indicate that sequences within the cytoplasmic domain of beta4 determine the subcellular distribution of BP180.

Relation between gastric cancer and previous peptic ulcer disease

BACKGROUND

It is presently not well understood to what extent peptic ulcer and gastric cancer represent related diseases.

AIMS

The objective of this study was to assess past occurrence of gastric and duodenal ulcers in patients with cancer of the gastric cardia or other parts of the stomach.

METHODS

The association between peptic ulcer and gastric cancer was studied among patients followed up at hospitals of the US Department of Veterans Affairs. Two populations of 1069 subjects with cancer of the cardia and 3078 subjects with cancer of other parts of the stomach were compared with a control population of 89082 subjects without gastric cancer. In multivariate logistic regressions, presence or absence of cancer served as the outcome variable, while age, sex, race, previous histories of gastric ulcer, duodenal ulcer, peptic ulcer site unspecified, gastric resection, or vagotomy served as modifier variables.

RESULTS

Old age, non-white ethnicity, and male sex proved strong and independent risk factors for non-cardiac gastric cancer. A previous history of gastric, but not duodenal ulcer was associated with a significantly raised odd ratio of 1.53 (95% confidence interval: 1.24 to 1.87). Cancer of the cardia affected predominantly whites, and was relatively more common in men than non-cardiac gastric cancer. Past gastric ulcers exerted no significant influence (1.02, 0.67 to 1.56), while duodenal ulcers and peptic ulcer site unspecified were protective (duodenal ulcer: 0.68, 0.47 to 0.95; peptic ulcer disease: 0.66, 0.47 to 1.00). Partial gastrectomy was a risk factor for non-cardiac gastric cancer (1.86, 1.32 to 2.63), but not for cancer of the cardia (1.09, 0.54 to 2.20).

CONCLUSION

These epidemiological patterns might stem from underlying differences in the influences of gastritis and acid secretion on the development of the two cancer types.

The subcellular distribution of the high molecular mass protein, HD1, is determined by the cytoplasmic domain of the integrin beta 4 subunit

The high molecular mass protein, HD1, is a structural protein present in hemidesmosomes as well as in distinct adhesion structures termed type II hemidesmosomes. We have studied the distribution and expression of HD1 in the GD25 cells, derived from murine embryonal stem cells deficient for the beta 1 integrin subunit. We report here that these cells possess HD1 but not BP230 or BP180; two other hemidesmosomal constituents, and express only traces of the alpha 6 beta 4 integrin. By immunofluorescence and interference reflection microscopy HD1 was found together with vinculin at the end of actin filaments in focal contacts. In OVCAR-4 cells, derived from a human ovarian carcinoma which, like GD25 cells, only weakly express alpha 6 beta 4, HD1 was also localized in focal contacts. Upon transfection of both GD25 and OVCAR-4 cells with cDNA for the human beta 4 subunit the subcellular distribution of HD1 changed significantly. HD1 is then no longer present in focal contacts but in other structures at cell-substrate contacts, colocalized with alpha 6 beta 4. These junctional complexes are probably the equivalent of the type II hemidesmosomes. Transfection of GD25 cells with beta 1 cDNA did not affect the distribution of HD1, which indicates that the localization of HD1 in focal contacts was not due to the absence of beta 1. Moreover, in GD25 cells transfected with cDNA encoding a beta 4/beta 1 chimera, in which the cytoplasmic domain of beta 4 was replaced by that of beta 1, the distribution of HD1 was unaffected. Our findings indicate that the cytoplasmic domain of beta 4 determines the subcellular distribution of HD1 and emphasize the important role of alpha 6 beta 4 in the assembly of hemidesmosomes and other junctional adhesive complexes containing HD1.

Economic aspects of endoscopic screening for intestinal precancerous conditions

The relationship of costs to effectiveness in endoscopic screening depends on the incidence rate of cancers arising from precancerous lesions, the sensitivity and specificity rates of endoscopic screening, and the effectiveness of timely diagnosis and surgery in preventing death. Because all these parameters, which enter a medical decision analysis, have a relatively large margin of error, it is not possible to resolve the issue whether a screening should be performed based on economic analyses alone. A crude "back of the envelope" comparison of different screening programs suggests that colonoscopy in ulcerative colitis would result in the highest yield and gastroscopy of the gastric stump in the lowest yield.

Association of esophagitis and esophageal strictures with diseases treated with nonsteroidal anti-inflammatory drugs

BACKGROUND

It has been speculated that intake of nonsteroidal anti-inflammatory drugs (NSAIDs) represents a risk factor for the occurrence of esophagitis and esophageal strictures.

METHODS

A case-control study was conducted to compare the occurrence of comorbid diseases treated with NSAIDs in case and control subjects with and without esophageal disease, respectively. The case population was comprised of all patients with esophagitis (International Classification of Diseases code 530.1) or esophageal stricture (code 530.3) who were discharged from hospitals of the Department of Veteran Affairs between 1981 and 1994. In separate multivariate logistic regressions, the occurrence of esophagitis or esophageal stricture served as the outcome variable, and age, gender, ethnicity, and comorbid occurrence of an NSAID-related diagnosis served as modifier variables.

RESULTS

A total of 101,366 individual case subjects were included, of whom 92,860 presented with esophagitis and 14,201 with stricture. The occurrence of erosive esophagitis was associated with osteoarthritis (odds ratio = 1.42, 95% confidence interval = 1.36-1.48), osteoporosis (1.38, 1.25-1.52), back pain (1.49, 1.42-1.56), femur bone fracture (1.46, 0.92-2.32), fibrositis (1.57, 1.41-1.75), tension headache (1.34, 1.27-1.40), ankylosing spondylitis (1.33, 1.24-1.42), rheumatoid arthritis (1.13, 1.05-1.21), sicca syndrome (1.15, 1.05-1.26), and systemic sclerosis (6.16, 4.65-8.14). NSAID-related diagnoses represented similar risk factors for both esophagitis and esophageal stricture.

CONCLUSIONS

A large variety of diseases treated by NSAIDs are associated with a significantly increased risk of esophageal erosion or stricture; the risk appears similar for both of these. In some comorbid conditions, the underlying disease process may contribute to the occurrence of esophageal pathology.

Colorectal cancer after gastric surgery: a meta-analysis

BACKGROUND

Until now, the question of whether previous gastric surgery results in an increased risk of colorectal cancer has remained controversial. A meta-analysis was performed to resolve this issue.

METHODS

The numbers of colorectal tumors in the two populations with and without gastric surgery were retrieved from all relevant articles found through a MEDLINE search. If available, the most detailed breakdown of the data by patient gender, type of peptic ulcer, type of surgery, time since gastric surgery, and by tumor location was chosen. The Mantel-Haenszel procedure was used to calculate a weighted odds ratio from the individual studies. The method of DerSimonian and Laird was used to calculate a weighted average of the difference between tumor rates in patients with and without gastric surgery.

RESULTS

The summary odds ratio was 1.09 with a 95% confidence interval of 0.96-1.24. The length of time after surgery, gender, tumor location, initial ulcer type, and different types of surgery were not associated with any significant influence. The summary rate difference was not significantly different from zero. The test for heterogeneity yielded a chi 2 = 26.87, df = 13, p = 0.013. After ignoring one obvious outlier study, the chi 2 test dropped to a nonsignificant level. A L'Abbé plot failed to show any prevailing influence of rate size on the overall heterogeneity among the various studies.

CONCLUSIONS

Surgery for peptic ulcer does not result in an increased risk for colorectal tumors. This lack of influence was shown consistently by all tests of the present meta-analysis.

Distribution of laminin variants and their integrin receptors in human secondary lymphoid tissue. Colocalization suggests that the alpha 6 beta 4-integrin is a receptor for laminin-5 in lymphoid follicles

Laminins are a family of multifunctional basement membrane glycoproteins. Over the last years, many laminin isoforms have been characterized, which were shown to be composed of distinct combinations of variant alpha, beta and gamma chains. Some of these isoforms show remarkable tissue specificity, which suggests functional involvement in local processes. In this study the previously described mAb 4C7, which recognize epithelial basement membranes as well as endothelial basement membranes in lymphoid follicles, was identified as an anti-laminin-5 antibody. Using a set of mAbs against various variant laminin chains we established that specifically the gamma 2 chain of laminin-5 was confined to the endothelial basement membranes of vessels in lymphoid follicles, whereas other variant laminin chains were also expressed elsewhere in the lymphoid follicles, whereas other variant laminin chains were also expressed elsewhere in the lymphoid tissue. Additionally, the expression of the known integrin receptors of laminin-5 was also examined. The alpha 6 beta 4 integrin-receptor for laminin was found to be colocalized with the laminin-5 gamma 2 chain on the abluminal surface of endothelial cells, whereas the alpha 3 integrin chain could not be detected in lymphoid follicles. This finding suggests that the alpha 6 beta 4 integrin (and not the alpha 3 beta 1 integrin) serves as a laminin-5 receptor on endothelial cells in the follicular compartment of lymphoid tissue. Furthermore, alpha 6 beta 4 was also found in the same punctuated pattern on FDCs as laminin-5. The function of the laminin-alpha 6 beta 4 complex in this particular localisation is still obscure, but a role in the maintainance of the follicular compartment via hemidesmosome-like attachment sites is postulated.

The role of the cytoplasmic domain of alpha 6 integrin in the assembly and function of alpha 6 beta 1 and alpha 6 beta 4

We have studied the role of the cytoplasmic domain of alpha 6 in the assembly and function of the alpha 6 beta 4 integrin, and compared it with the role of alpha 6 in the assembly and function of alpha 6 beta 1, by transfection of cDNAs encoding cytoplasmic mutants of alpha 6 into K562 cells with or without full-length beta 4 cDNA. Des-(1022-1050)-alpha 6, which contains a deletion C-terminal to the GFFKR motif, was expressed in association with beta 1, but associated preferentially with beta 4, whereas the wild-type alpha 6 subunit associated efficiently with beta 1 and beta 4. Des-(1016-1050)-alpha 6, which lacked also the GFFKR sequence, was only expressed at the cell surface when beta 4 was available. Transient expression in COS-7 cells showed that des-(1016-1050)-alpha 6 was retained in the endoplasmic reticulum as a monomer, which suggests that truncation of the cytoplasmic domain reduces the affinity of alpha 6 for beta 1, particularly when the GFFKR sequence is absent. Although the GFFKR motif is not essential for association of alpha 6 with beta 4, it increases the stability of the alpha 6 beta 4 integrin. The cytoplasmic domain of alpha 6 is essential for inside-out and outside-in signaling via the alpha 6 beta 1 receptor, but not for adhesion via alpha 6 beta 4. We show that alpha 6 beta 4 is a constitutively active receptor. Thus, unlike adhesion by most other integrins, adhesion by alpha 6 beta 4 does not seem to depend on any active cellular process. Binding of alpha 6 beta 4 to ligand was only slightly affected by truncation of the alpha 6 cytoplasmic domain N-terminal to the GFFKR sequence and became partially dependent on metabolic energy. These data indicate that truncations of the cytoplasmic domain of the alpha 6 subunit affect the assembly and function of alpha 6 beta 1 more strongly than those of alpha 6 beta 4. This difference may be due to the greater affinity of alpha 6 for beta 4 than for beta 1, which makes alpha 6 beta 4 less susceptible to the effect of truncations.

Comorbid occurrence of cholelithiasis and gastrointestinal cancer

OBJECTIVE

To test whether gallstone disease represents a general risk factor for gastrointestinal cancer.

METHODS

The comorbid occurrences of cholelithiasis or choledocholithiasis with cancers of the biliary tract, pancreas, small and large intestine were analysed in a population of 3.41 million military veterans who were discharged from VA hospitals distributed throughout the USA between 1981 and 1993. Comorbidity was calculated as the ratio between the observed and expected number of hospitalized veterans with cholelithiasis plus cancer. A 95% confidence interval was calculated based on the Poisson distribution of the observed number of patients with comorbidity.

RESULTS

In cholelithiasis, the ratio of comorbid occurrence with biliary cancer was 4.59 (4.06-5.31). In choledocholithiasis, the ratio of comorbid occurrence with biliary cancer was 9.31 (7.20-11.84) and with pancreatic cancer 4.34 (3.80-4.94). These ratios remained significant when the analyses were confined to cholelithiasis or choledocholithiasis documented before the first diagnosis of cancer. The ratios of the comorbid occurrences between cholelithiasis and cancers of the small or large intestine were only significant when total comorbid occurrences were analysed, but vanished in the analysis restricted to cholelithiasis or choledocholithiasis documented before the first diagnosis of cancer.

CONCLUSION

The occurrence of gallstones represents a risk factor for pancreaticobiliary cancer, but not cancers involving other parts of the gastrointestinal tract. This association appears particularly strong in patients with choledocholithiasis.

Hemidesmosomes: roles in adhesion, signaling and human diseases

Our understanding of the role of hemidesmosomes in cell-substratum adhesion has greatly improved both as a result of targeted gene mutation experiments and by means of observations of several blistering disorders of the skin in which the absence or defects of hemidesmosomal proteins have been demonstrated. Functionally important domains within the proteins that constitute hemidesmosomes have recently been identified by transfection and mutagenesis studies. These multiprotein complexes appear not only to mediate cell adhesion, but also to transduce signals from the extracellular matrix to the cell interior that may profoundly modulate cell behavior.

Cost-benefit analysis of testing for Helicobacter pylori in dyspeptic subjects

OBJECTIVES

It has remained controversial how to manage patients who present with symptoms of dyspepsia. Should all dyspeptic patients undergo a radiological or endoscopic procedure to diagnose peptic ulcer, or would a serological test for Helicobacter pylori provide sufficient evidence to start all H. pylori-positive patients on empirical antibiotic therapy?

METHODS

The outcome of serological testing for H. pylori in dyspepsia is analyzed using a decision tree. Successful eradication is associated with the potential benefits of healing dyspepsia and preventing peptic ulcer or gastric cancer. In a sensitivity analysis, all of the transition rates and benefits are varied over a wide range to test the robustness of the calculated decision outcomes.

RESULTS

The cost-benefit relationship of serological screening for H. pylori in dyspeptic patients is influenced primarily by the response rate of nonulcer dyspepsia to H. pylori eradication and secondly by the monetary benefit of ulcer prevention and the prevalence rate of peptic ulcer in H. pylori-positive patients. A response to H. pylori eradication in 5-10% of all patients with nonulcer dyspepsia would make screening and treatment for H. pylori a beneficial option, irrespective of any other potential benefits. If ulcer prevention were associated with long term benefit of $4000 or more and if the ulcer prevalence rate exceeded 10% of all dyspeptic patients, serological screening for H. pylori would also pay off.

CONCLUSIONS

As long as no unequivocal evidence exists that nonulcer dyspepsia responds to eradication of H. pylori, treating all dyspeptic patients who test positive for H. pylori cannot be recommended. At the present time, antibiotic therapy should be reserved to patients with proven ulcer or to patients with nonulcer dyspepsia for whom other measures have failed.

Epithelial detachment due to absence of hemidesmosomes in integrin beta 4 null mice

Integrins are heterodimeric transmembrane glycoproteins which are engaged in a variety of cellular functions, such as adhesion, migration and differentiation1. The integrin alpha 6 beta 4 is expressed on squamous epithelia, on subsets of endothelial cells, immature thymocytes and on Schwann cells and fibroblasts in the peripheral nervous system. In stratified epithelia, alpha 6 beta 4 is concentrated in specialised adhesion structures, called hemidesmosomes, which are implicated in the stable attachment of the basal cells to the underlying basement membrane by connecting the intermediate filaments with the extracellular matrix. The nature of the interactions between the various hemidesmosomal proteins, that lead to the formation of hemidesmosome is poorly understood. To study the contribution of the integrin alpha 6 beta 4 in hemidesmosome formation and their anchoring properties, we inactivated the beta 4 gene in mice by targeted gene disruption. Homozygous beta 4 null mice died shortly after birth and displayed extensive detachment of the epidermis and other squamous epithelia. The dramatically reduced adhesive properties of the skin was accompanied by the absence of hemidesmosomes at the basal surface of keratinocytes. No evidence was found for impaired T-cell development, nor for defects in myelination in the peripheral nervous system.

Deficiency of the integrin beta 4 subunit in junctional epidermolysis bullosa with pyloric atresia: consequences for hemidesmosome formation and adhesion properties

Junctional epidermolysis bullosa (JEB) comprises a group of inherited autosomal recessive blistering disorders characterized by dermo-epidermal separation through the lamina lucida of the basement membrane. We identified a patient with JEB associated with pyloric atresia (PA), in whom the integrin beta 4 subunit was completely absent. At the ultrastructural level, the hemidesmosomes were reduced in number, appeared rudimentary and lacked a subbasal dense plate and frequently an inner attachment plaque. However, keratin filaments were still anchored to the cytoplasmic plaque of the hemidesmosome. Immunofluorescence analysis showed that the beta 4 subunit was absent in the skin of the PA-JEB patient, whereas the alpha 6 subunit appeared to be normally distributed along the basement membrane zone, as were the other hemidesmosomal components BP230, BP180 and HD1. Furthermore, the alpha 3 and beta 1 subunits were not only detected at the lateral membranes of basal cells in PA-JEB skin, as in normal skin, but also along the basement membrane zone. The few hemidesmosome-like structures found in cultured keratinocytes from the PA-JEB patient contained the hemidesmosomal components BP230, BP180 and HD1, but not the integrin alpha 6 subunit. Like alpha 3, this subunit was colocalized with vinculin in focal contacts at the ends of actin stress fibers. Immunoprecipitation analysis revealed that alpha 6 was associated with beta 1 on PA-JEB keratinocytes, whereas normal human keratinocytes (NHKs) exclusively express alpha 6 beta 4 on their cell surface. The initial adhesion of PA-JEB and normal keratinocytes to laminin-1 and laminin-5, both ligands for alpha 6 beta 1 and alpha 6 beta 4, was similar. In migration assays, the PA-JEB keratinocytes were more motile on laminin-5 than normal keratinocytes. Our observations indicate that the integrin alpha 6 beta 4 plays a crucial role in the proper assembly of hemidesmosomes and in the stabilization of the dermal-epidermal junction. The fragility of the skin and the blistering in this patient appear to have been due to the deficiency of the integrin beta 4 subunit, which results in the formation of too few and structurally abnormal hemidesmosomes.

Genomic organization of the mouse beta 1 gene: conservation of the beta 1D but not of the beta 1B and beta 1C integrin splice variants

We have determined the genomic organization of the 3'-region of the murine beta 1 gene and cloned the murine beta 1D integrin splice variant. Overlapping genomic clones encompassing the region of the beta 1D-specific exons were isolated from a phage lambda FIXII library, mapped and partially sequenced. All of the exon-intron junctions identified in the murine beta 1 gene fit with the consensus splice donor and acceptor sequences and occur at the same positions as in their human counterparts. cDNA clones for the beta 1D integrin were isolated from a murine skeletal muscle library. The human and murine beta 1D sequences are conserved at the nucleotide (93%) and amino acid (100%) level, suggesting an important role of this muscle-specific variant throughout mammalian phylogenesis. In contrast, murine sequences for beta 1B are very different from human beta 1B at both the nucleotide as well as amino acid level. Moreover, no specific polyadenylation signal for the beta 1B variant could be identified in genomic clones, suggesting that this variant is not present in the mouse. Finally, we were not able to identify a murine beta 1C splice variant by sequencing analysis, Southern hybridization techniques or polymerase chain reaction of mRNA from platelets. These findings indicate that the beta 1B and beta 1C variants emerged relatively late in the phylogenesis of the beta 1 integrin family.

Cleavage of the alpha6A subunit is essential for activation of the alpha6Abeta1 integrin by phorbol 12-myristate 13-acetate

The alpha6 integrin subunit is proteolytically cleaved during biosynthesis in a covalently associated heavy and light chain. To examine the importance of cleavage for the function of the alpha6 subunit, we introduced mutations in the cDNA encoding the RKKR (876-879) sequence, the presumed cleavage site, in which either one or two basic residues were replaced by glycine. Wild-type and mutant alpha6A cDNAs (alpha6GKKR, alpha6RKKG and alpha6RGGR) were transfected into K562 cells. The mutant alpha6A integrin subunits were expressed in association with endogenous beta1, at levels comparable to that of the wild-type alpha6Abeta1. A single alpha6A polypeptide chain (150 kDa) was precipitated from surface-labeled alpha6GKKR, alpha6RKKG, and alpha6-RGGR transfectants, while the separate heavy (120 kDa) and light chains (31 or 30 kDa) were precipitated from the wild-type alpha6RKKR transfectant. Thus, a change in the RKKR sequence prevents cleavage of alpha6. After activation by the anti-beta1 stimulatory mAb TS2/16 both cleaved and uncleaved alpha6Abeta1 integrins bound and spread on laminin-1. Remarkably, the phorbol ester phorbol 12-myristate 13-acetate, which activates wild-type alpha6Abeta1 to bind to laminin-1, did not activate uncleaved alpha6Abeta1. We conclude that uncleaved alpha6Abeta1 is capable of ligand binding and transducing outside/in signals, like wild-type alpha6A-beta1. However, inside/out signaling is affected. It appears that cleavage of alpha6 is required to generate the proper conformation in alpha6 that enables affinity modulation of the alpha6A-beta1 receptor by phorbol 12-myristate 13-acetate.

Generalized atrophic benign epidermolysis bullosa. Either 180-kd bullous pemphigoid antigen or laminin-5 deficiency

BACKGROUND

Generalized atrophic benign epidermolysis bullosa (GABEB) is a form of nonlethal junctional epidermolysis bullosa, clinically characterized by generalized blistering after birth, atrophic healing, and incomplete universal atrophic alopecia with onset in childhood. Recently, we discovered a deficiency of the 180-kd bullous pemphigoid antigen (BP180) and a reduced amount of BP180 messenger RNA in three patients with GABEB. It is not yet clear, however, whether GABEB is invariably caused by BP180 deficiency.

RESULTS

We examined 18 patients with nonlethal junctional epidermolysis bullosa from unrelated families; nine of these individuals presented with the clinical characteristics of GABEB. Specimens of clinically normal skin obtained from the patients were stained by immunofluorescence with monoclonal antibodies to BP180 and laminin-5. The BP180 epitopes were not expressed in eight patients, all of whom were sharing the typical clinical features of GABEB. In one of the nine patients with GABEB, the BP180 level was sufficient, but the laminin-5 level was reduced. Among the nine patients with junctional epidermolysis bullosa without atrophic alopecia, laminin-5 level was not expressed in one patient, while in the other patients both antigens were normally expressed.

CONCLUSIONS

Not all patients with GABEB are deficient in BP180, since some individuals with GABEB only exhibit reduction of the laminin-5 expression. The BP180 deficiency in the skin invariably seems to result in GABEB. Immunofluorescence analysis using monoclonal antibodies against BP180 (and laminin-5) may allow early subtyping, which is of prognostic significance, in children born with junctional epidermolysis bullosa.

The prevalence of self-reported peptic ulcer in the United States

OBJECTIVES

The purpose of this study was to draw a current picture of the sociodemographic characteristics of peptic ulcer in the United States.

METHODS

During the National Health Interview Survey of 1989, a special questionnaire on digestive diseases was administered to 41,457 randomly selected individuals. Data were retrieved from public use tapes provided by the National Center for Health Statistics. Odds ratios were calculated by logistic regression after adjustment for sample weights in the survey.

RESULTS

Of adult US residents, 10% reported having physician-diagnosed ulcer disease, and one third of these individuals reported having an ulcer in the past year. Old age, short education, low family income, being a veteran, and smoking acted as significant and independent risk factors. Gastric and duodenal ulcer occurred in both sexes equally often. Duodenal ulcer was more common in Whites than non-Whites, while gastric ulcer was more common in non-Whites.

CONCLUSIONS

The age-related rise and socioeconomic gradients of peptic ulcer represent the historic scars of previous infection rates with Helicobacter pylori. The racial variations reflect different ages at the time of first infection; younger and older age at the acquisition of H. pylori appear to be associated with gastric and duodenal ulcer, respectively.

Risk factors of colorectal cancer in inflammatory bowel disease

BACKGROUND

It is unknown whether colorectal cancer (CRC) in patients with inflammatory bowel disease (IBD) behaves differently from regular CRC in patients without IBD. A case-control study was conducted to compare CRC in patients with and without underlying IBD.

METHODS

The Department of Veterans Affairs (VA) maintains a computerized file of all hospital discharges among U.S. military veterans since 1970. This file accrues the data of 1 million hospital discharges per year. All patients with IBD and all patients with CRC who had been discharged from a VA hospital between 1981 and 1993 were selected. The influence of various risk factors on the occurrence of CRC in IBD and its mortality in patients with and without IBD was tested by logistical regression analyses.

RESULTS

Of the 11,446 subjects with IBD, 371 had colon cancer. CRC was diagnosed in 52,243 subjects without IBD. CRC patients with IBD were 7 yr younger than those without IBD, but in patients with Crohn's disease, more cancers were located in the proximal colon (chi 2 = 18.10, df = 5, p = 0.003). The occurrence of CRC in IBD was influenced by the following risk factors: age [odds ratio (OR) = 1.45, 95% confidence interval (CI) = 1.35-1.57], sclerosing cholangitis (OR) = 3.41, CI = 2.03-5.73), and history of a disease associated with consumption of nonsteroidal anti-inflammatory drugs (NSAID) (OR = 0.84, CI = 0.65-1.09). Sex, race, and type of IBD did not exert a significant influence on the development of cancer. Cancer-related mortality was influenced by the following risk factors: age (OR = 1.16, CI = 1.14-1.18), male gender (OR = 1.23, CI = 1.06-1.44), white race (OR) = 0.97, CI = 0.96-0.99), and history of NSAID consumption (OR = 0.68, CI = 0.65-0.72). Presence of IBD was not associated with a significant influence on CRC mortality (OR = 1.00, CI = 0.70-1.43).

CONCLUSIONS

CRC affects IBD patients at a younger age and is characterized by a more proximal localization when compared with CRC of non-IBD patients. NSAID exert a protective influence against CRC in patients with IBD similarly as in patients without IBD. Sclerosing cholangitis is associated with a strong risk of developing colon cancer in patients with IBD.

Prevention of colorectal cancer by flexible endoscopy and polypectomy. A case-control study of 32,702 veterans

OBJECTIVE

To determine whether patients with colorectal cancer are less likely than unaffected controls to have had one or more endoscopic procedures (flexible sigmoidoscopy, colonoscopy, or polypectomy) before being diagnosed with cancer.

DESIGN

Case-control study.

SETTING

Hospitals of the Department of Veterans Affairs.

PATIENTS

8722 and 7629 case-patients with colon and rectal cancer, respectively, and age-, sex-, race-matched controls who were discharged at the same time as the corresponding case-patients.

MEASUREMENTS

Number and type of endoscopic procedures of the large bowel done from 1981 until the development of colorectal cancer in each case-patient. The influence of endoscopic procedures on the development of colorectal cancer was tested by conditional multiple logistic regression analysis.

RESULTS

Compared with controls, patients with colorectal cancer were less likely to have had an endoscopic procedure of the large bowel before being diagnosed with cancer (odds ratio for colon cancer, 0.51 [95% CI, 0.44 to 0.58]; odds ratio for rectal cancer, 0.55 [CI, 0.47 to 0.64]). In patients who had flexible sigmoidoscopy, colonoscopy, and polypectomy, the odds ratios were even smaller. When analyzed by separate 1-year intervals, patients with cancer had significantly fewer procedures during periods of up to 6 years before their onset of their cancer. Similarly, fewer inpatient and outpatient procedures were done in patients than in controls.

CONCLUSIONS

Endoscopic procedures of the large bowel reduce the risk for developing colon and rectal cancer by 50%, their protective influence lasting 6 years.

Expression patterns of laminin receptor splice variants alpha 6A beta 1 and alpha 6B beta 1 suggest different roles in mouse development

The alpha 6 beta 1 integrin is a receptor for laminins and is present from early stages of mouse embryogenesis. In the present study we determined the temporal and spatial expression of the two cytoplasmic splice variants of the alpha 6 integrin subunit, alpha 6A and alpha 6B, in the early- and mid-gestation mouse postimplantation embryo using RT-PCR, in situ hybridization, and immunofluorescence. Our results show that alpha 6B is present in the embryo at all stages studied and is expressed before alpha 6A. alpha 6A expression begins in 8.5 day p.c. embryos and is initially exclusively localized to the developing heart. In 8.5 (and 9.5) day p.c. embryos alpha 6A mRNA and protein are present in a gradient in the myocardium of the heart tube from strongest expression in the sinus venosus and in the common atrial chamber to a weakening expression along the ventricle and bulbus cordis. In 10.5 day p.c. embryos this gradient is less evident and in 12.5 day p.c. embryos alpha 6A mRNA and protein are present in comparable amounts between atria and ventricles. Neither alpha 6A nor alpha 6B is present in endocardial cushion tissue. By day 12.5 p.c. alpha 6A expression is also present in the developing epidermis, dental primordia, lens, gonads, and in a few epithelia such as those of the digestive tract. alpha 6B expression is always much more widespread than alpha 6A expression. For example, only alpha 6B is present in the myotome of the somites of 9.5 day p.c. embryos, in the developing central and peripheral nervous systems, and in the nephrogenic system at all stages studied, except after the differentiation of the gonads when alpha 6A is also present. Furthermore, alpha 6B is the only splice variant present on endothelial cells. We also examined the distribution of the beta 4 integrin subunit to determine whether the alpha 6 beta 4 integrin was present during these stages of development. Beta 4 protein was absent in early postimplantation stages but was present in the epidermis and digestive tract of 12.5 day p.c. embryos. These results show a differential distribution of alpha 6A and alpha 6B during mouse development and thus strongly suggest a different function of these splice variants during embryogenesis. Our results point to a possible role for the alpha 6A beta 1 integrin in the development of the myocardium of the developing heart, but not in the migration of endocardial cushion cells, while alpha 6B beta 1 could be important in the developing nephrogenic and nervous systems.

Distribution of extracellular and cytoplasmic domains of the alpha 3 and alpha 6 integrin subunits in solid tumors

Integrins play an important role in malignant transformation and the invasion of tumors. They mediate cell-cell and cell-matrix interactions and participate in transduction of signals across the plasma membrane, processes dependent on the extracellular and cytoplasmic domains of integrins. We studied a selection of solid tumors by immunohistochemistry using monoclonal antibodies (MAbs) against the extracellular domain and the cytoplasmic variants (A and B) of the alpha 3 and alpha 6 integrin subunits. The tissue-specific expression of ecto- and cyto-domains of alpha 3 and alpha 6 is maintained in a subset of breast, colon, kidney and parotid tumors. In a few breast tumors, there was a switch in variant expression in that alpha 6B was detected instead of alpha 6A in normal breast tissue. In many colon and parotid tumors, one of the variants of alpha 6 was missing, while both were detectable in the corresponding normal tissues. In contrast, coexpression of the alpha 6 variants was found in some kidney tumors, whereas only one of the variants was detected in the normal tissue. In a minority of colon and kidney tumors, the cyto-domains of alpha 3 and alpha 6 were undetectable and total absence of alpha 3 and alpha 6 was noted in a subset of breast, colon, kidney and parotid tumors. These observations show that expression of the integrin variants in tumors varies considerably and support the concept that changes in expression may contribute to malignant behavior.

Protection by endoscopy against death from colorectal cancer. A case-control study among veterans

BACKGROUND

Although several clinical and epidemiologic studies suggest that timely diagnostic procedures of the large bowel may reduce mortality from colorectal cancer, the evidence for this relationship is primarily circumstantial.

METHODS

A case-control study was conducted among hospitalized US military veterans to investigate whether diagnostic procedures of the large bowel were performed in the period preceding the diagnosis of colorectal cancer less frequently in patients dying of colorectal cancer than in control patients. Data files of a total of 4411 veterans dying of colorectal cancer between 1988 and 1992 were extracted from the records of the US Department of Veterans Affairs, Washington, DC. Data of four living control patients and four dead control patients without colorectal cancer were matched by age, sex, and race to each case patient. The case and the two control populations were compared by conditional logistic regression, calculating odds ratios, and their 95% confidence interval.

RESULTS

Diagnostic procedures of the large bowel reduced mortality from colorectal cancer, the odds ratio being 0.41 (range, 0.33 to 0.50) for the comparison with living control patients. The protective effects of proctosigmoidoscopy, colonoscopy, and polypectomy lasted for 5 years. The procedures were protective against death from cancer of the colon, as well as cancer of the rectum. The most protective influence was associated with removal of tissue through biopsy, fulguration, and polypectomy. Similar influences were found comparing case patients with dead control patients.

CONCLUSION

Removal of tissue represents the most effective means to reduce mortality from cancers of the large bowel. It retains its efficacy over a time period of 5 years.

Associations of peptic ulcer and gastric cancer with other diseases in US veterans

OBJECTIVES

The purpose of this study was to examine, through the database of the Department of Veterans Affairs, the joint occurrence of different diseases in individual patients.

METHODS

Patients with a diagnosis of gastric cancer, gastric ulcer, or duodenal ulcer were extracted from the 1987 through 1990 computer files. A random sample of patients from each annual file served as a control population. All previous discharges of each case or control patient between 1970 and 1990 were searched for the occurrence of hypertensive diseases or chronic diseases of the joints, lungs, pancreas, and liver. The relative frequencies of such diagnoses in case and control patients were compared by multivariate logistic regression.

RESULTS

Gastric ulcer and duodenal ulcer, but not gastric cancer, were significantly associated with chronic diseases of the joints, lungs, pancreas, and liver. None of the three diagnoses showed any significant association with hypertensive diseases.

CONCLUSIONS

These relationships may reflect the influence of nonsteroidal anti-inflammatory drugs, smoking, and alcohol. They stress the importance of environmental risk factors other than Helicobacter pylori in terms of damage to the upper gastrointestinal mucosa.

A novel beta 1 integrin isoform produced by alternative splicing: unique expression in cardiac and skeletal muscle

The mRNA's of several integrin subunits are alternatively spliced in the region encoding cytoplasmic domains, that may potentially provide alternative integrin-cytoskeleton interactions and transmembrane signaling pathways. We identified a novel cytoplasmic tail variant of the human beta 1 subunit by reverse transcriptase polymerase chain reaction. This fourth beta 1 variant, named beta 1D, is specific for skeletal and cardiac muscle. The determined genomic organization of the 3'-region of the human beta 1 gene reveals that beta 1D is produced by alternative splicing of mRNA. In addition, we show that the expression of beta 1D is developmentally regulated during murine myoblast differentiation, suggesting a role for beta 1D in myogenesis.