Hemidesmosomes: molecular organization and their importance for cell adhesion and disease

In the skin, basal epithelial cells constantly divide to renew the epidermis. The newly formed epithelial cells then differentiate in a process called keratinization, ultimately leading to the death of these cells and a pile-up of cell material containing vast amounts of keratins. The basal keratinocytes in skin are attached to their underlying basement membrane via specialized adhesion complexes termed hemidesmosomes (HDs). These complexes ascertain stable adhesion of the epidermis to the dermis, and mutations in components of these complexes often result in tissue fragility and blistering of the skin. In this review, we will describe the various hemidesmosomal proteins in detail as well as, briefly, the protein families to which they belong. Specifically, we will report the protein-protein interactions involved in the assembly of hemidesmosomes and their molecular organization. Some signaling pathways involving primarily the alpha6beta4 integrin will be discussed, since they appear to profoundly modulate the assembly and function of hemidesmosomes. Furthermore, the importance of these hemidesmosomal components for the maintenance of tissue homeostasis and their involvement in various clinical disorders will be emphasized. Finally, we will present a model for the assembly of HDs, based on our present knowledge.

Role of binding of plectin to the integrin beta4 subunit in the assembly of hemidesmosomes

We have previously shown that plectin is recruited into hemidesmosomes through association of its actin-binding domain (ABD) with the first pair of fibronectin type III (FNIII) repeats and a small part of the connecting segment (residues 1328-1355) of the integrin beta4 subunit. Here, we show that two proline residues (P1330 and P1333) in this region of the connecting segment are critical for supporting beta4-mediated recruitment of plectin. Additional binding sites for the plakin domain of plectin on beta4 were identified in biochemical and yeast two-hybrid assays. These sites are located at the end of the connecting segment (residues 1383-1436) and in the region containing the fourth FNIII repeat and the C-tail (residues 1570-1752). However, in cells, these additional binding sites cannot induce the assembly of hemidesmosomes without the interaction of the plectin-ABD with beta4. Because the additional plectin binding sites overlap with sequences that mediate an intramolecular association of the beta4 cytoplasmic domain, we propose that they are not accessible for binding and need to become exposed as the result of the binding of the plectin-ABD to beta4. Furthermore, these additional binding sites might be necessary to position the beta4 cytoplasmic domain for an optimal interaction with other hemidesmosomal components, thereby increasing the efficiency of hemidesmosome assembly.

Alimentary diseases in the poor and middle class in London 1773-1815, and in New York poor 1797-1818

BACKGROUND

Although dyspepsia has been described for thousands of years, few studies have analysed its incidence before the 19th century when peptic ulcer first became a major dyspepsia-producing disease.

METHODS

The incidence of alimentary disease around 1800 was examined in three private practices for the fee-paying middle class and in five public dispensaries for the poor in London, as well as in one dispensary in New York.

RESULTS

The proportions of attendances for alimentary disorders were identical, 16%, in each of the three groups. Diarrhoea and dysentery were twice as common in the London dispensary than in private practice, presumably because of poor sanitation. Dyspepsia showed a similar incidence in the London dispensary and private practice, but was only half as common in New York. Worms were three times more common in dispensary patients in New York than in London. The incidence of diarrhoea and dyspepsia indicated no significant time trends over 43 years. None of the alimentary causes of death showed peptic ulcer at necropsy, and both haematemesis and intestinal haemorrhage were rare.

CONCLUSIONS

Around 1800, the infrequent deaths from alimentary conditions suggested that the ulcer epidemic had not yet started. Instead, it is probable that the dyspepsia was similar to the non-ulcer dyspepsia of today.

Inguinal hernia is not a sign of colon cancer: results of a prospective screening trial

BACKGROUND

It has been suggested that patients with an inguinal hernia harbour an increased risk for colorectal cancer.

METHODS

In a prospective clinical trial, we compared the prevalence of colonic neoplasms in 100 cases with inguinal hernia and 100 controls without inguinal hernia. The number, size, histology type, and the location of all colorectal lesions found during a screening flexible sigmoidoscopy were recorded.

RESULTS

Not a single case of colorectal cancer was detected in the patients with inguinal hernia pending surgical repair. In the asymptomatic control subjects, one Dukes A and one Dukes B1 colon cancer were detected. Polypectomy was performed in 15% and 17% of the case and control subjects, respectively. During a 5-year period following the initial screening procedure, none of the case or control subjects was diagnosed with colon cancer.

CONCLUSIONS

The decision for or against performing an endoscopic procedure in a patient with inguinal hernia should be guided by the general principles of screening for colorectal cancer. The mere presence of an inguinal hernia does not automatically increase the risk of colorectal cancer.

General principles to enhance practice patterns in gastrointestinal endoscopy

AIM

To develop general rules on how to pursue a therapeutic goal of interventional endoscopy without getting lost in abundant details.

METHODS

The influences of various medical interventions on the survival of a patient with gastrointestinal haemorrhage are modelled by an influence diagram. Survival is the focal point of multiple influences affecting its overall strength. Any downstream influence can represent the focal point of other preceding upstream influences. The mathematics underlying the influence diagram are similar to those of a decision tree with some notable exceptions. Its formalism allows one to consider inhibitory and additive influences and to include in the same analysis non-commensurable qualities, such as correct diagnosis, haemostasis or survival.

RESULTS

The analysis reveals five general rules. First, the large number of factors involved in successful endoscopy render the influence of each individual factor less important. Second, a single factor that exerts its influence on many subsequent factors tends to be associated with an overall greater relevance. Third, remote influences are of lesser relevance than those directly linked to the final outcome. Fourth, factors multiplied by several consecutive probabilities lose their influence. Fifth, endoscopists need to assess the relevance of individual factors with respect to the immediate goals of endoscopy, as well as the general goals of patient well-being.

CONCLUSIONS

The influence model of endoscopic haemostasis reveals several general principles that can be utilized as tools in endoscopy training.

Hospital admissions for peptic ulcer and indigestion in London and New York in the 19th and early 20th centuries

The occurrence of peptic ulcer increased rapidly in all Western countries from the 19th to the 20th century, attributed to a possible epidemic of Helicobacter pylori, a new pathogenic strain, or a change in host susceptibility. The early trends in hospital admissions for peptic ulcer and dyspepsia in London and New York during the 19th century are reviewed to test these hypotheses.

There are no reliable symptoms for erosive oesophagitis and Barrett's oesophagus: endoscopic diagnosis is still essential

AIMS

To evaluate the sensitivity and specificity of different symptoms in erosive reflux oesophagitis and Barrett's oesophagus.

METHODS

The presence of reflux symptoms was compared between a case population of 306 patients with endoscopically determined erosive reflux oesophagitis, 235 patients with biopsy-proven Barrett's oesophagus and a control population of 198 subjects without reflux disease.

RESULTS

Heartburn at any time and heartburn at night represented the only two symptoms to be simultaneously sensitive and specific. Symptoms that were induced by various foods, such as fat, tomato, chocolate, citrus or spices, tended to cluster in the same sub-group of patients. Similarly, heartburn induced by exercise, lying down or bending over tended to occur in the same sub-groups. The frequency of symptoms was influenced more by the presence of mucosal erosions than by the presence of Barrett's oesophagus. Reflux symptoms occurred more frequently in the presence rather than the absence of Barrett's oesophagus, and in long segment rather than short segment of Barrett's mucosa.

CONCLUSIONS

Endoscopic inspection of the oesophageal mucosa remains the only certain method by which to reliably diagnose erosive reflux oesophagitis and Barrett's oesophagus.

Medical decision analysis of endoscopic surveillance of Barrett's oesophagus to prevent oesophageal adenocarcinoma

BACKGROUND

Barrett's oesophagus is associated with an increased risk of the development of oesophageal adenocarcinoma. Endoscopic surveillance every 2-5 years has been recommended to prevent death from adenocarcinoma.

AIM

To assess the cost-effectiveness of this strategy.

METHODS

The incremental cost-effectiveness of surveillance (as compared to no surveillance) was analysed with a computer model of a Markov process.

RESULTS

Compared to no surveillance, the incremental cost-effectiveness of bi-annual endoscopy is 16,695 dollars per life-year saved. Surveillance is less cost-effective if the incidence rate of oesophageal adenocarcinoma is low and the 5-year survival rate is high. For surveillance to be cost-effective, there should be little reduction in health-related quality of life following surgical oesophagectomy to prevent death. Moreover, endoscopic surveillance and oesophagectomy need to be efficacious in reliably diagnosing high-grade dysplasia and preventing deaths from cancer. If such ideal conditions of surveillance are not met, the cost per life-year saved could rise five-fold.

CONCLUSIONS

Endoscopic surveillance of patients with Barrett's oesophagus may be a cost-effective means to prevent death from oesophageal adenocarcinoma.

Two different mutations in the cytoplasmic domain of the integrin beta 4 subunit in nonlethal forms of epidermolysis bullosa prevent interaction of beta 4 with plectin

The integrin alpha 6 beta 4 plays a crucial role in the assembly and maintenance of hemidesmosomes. Previous work has shown that the recruitment of plectin into hemidesmosomes is dependent on beta 4 and involves a region of the beta 4 cytoplasmic domain, which contains the first two fibronectin (FNIII) repeats and a short region of the connecting segment. Two missense mutations (R1225H and R1281W) in beta 4 that are responsible for nonlethal forms of epidermolysis bullosa are located in the second FNIII repeat. One of them is confined to a loop region that connects two beta strands (EC') whereas the other is located at the N-terminal end of the second FNIII repeat. We here report that these mutations render beta 4 unable to interact with plectin and prevent the localization of plectin in hemidesmosomes. Substitution of a lysine residue (K1279W) that forms part of the same loop as R1281 had no effect on the ability of beta 4 to recruit plectin. Furthermore, we show that an extended loop structure in beta 4, composed of the amino acids DDN (1262--1264), which resembles the RGD integrin-binding loop in fibronectin, is not involved in the binding to plectin. These results further demonstrate that binding of beta 4 to plectin is essential for the proper formation and function of hemidesmosomes and that loss of the interaction between beta 4 and plectin is associated with a mild form of epidermolysis bullosa.

A medical uncertainty principle

Acquisition of diagnostic knowledge and improvement of patient health often are mutually exclusive goals. A perfect understanding of a disease process is only obtained through unrestricted testing that exposes the patient to adverse events and discomfort. In a patient completely undisturbed by test procedures, the physician remains ignorant about the nature of the disease. The interplay of diagnostic knowledge and patient health can be formulated in terms of an uncertainty principle, which allows one to mathematically derive the parameters that influence the balance between the two competing goals. The majority of clinical conditions permit the pursuit of perfect diagnostic knowledge. Occasional medical disasters occur because physicians underestimate the patient's functional reserve or the cumulative toll exerted by multiple tests. Especially in emergency situations or serious illness, the maximum amount of knowledge that can be achieved is far less than perfect. Under such circumstances, the best management option takes into account a "calculated" amount of diagnostic uncertainty.

Gastric surgery is not a risk for Barrett's esophagus or esophageal adenocarcinoma

BACKGROUND & AIMS

The contribution of duodeno-gastroesophageal reflux to the development of Barrett's esophagus has remained an interesting but controversial topic. The present study assessed the risk for Barrett's esophagus after partial gastrectomy.

METHODS

The data of outpatients from a medicine and gastroenterology clinic who underwent upper gastrointestinal endoscopy for any reason were analyzed in a case-control study. A case population of 650 patients with short- segment and 366 patients with long-segment Barrett's esophagus was compared in a multivariate logistic regression to a control population of 3047 subjects without Barrett's esophagus or other types of gastroesophageal reflux disease.

RESULTS

In the case population, 25 (4%) patients with short-segment and 15 (4%) patients with long-segment Barrett's esophagus presented with a history of gastric surgery compared with 162 (5%) patients in the control population, yielding an adjusted odds ratio of 0.89 with a 95% confidence interval of 0.54-1.46 for short-segment and an adjusted odds ratio of 0.71 (0.30-1.72) for long-segment Barrett's esophagus. Similar results were obtained in separate analyses of 64 patients with Billroth-1 gastrectomy, 105 patients with Billroth-2 gastrectomy, and 33 patients with vagotomy and pyloroplasty for both short- and long-segment Barrett's esophagus. Caucasian ethnicity, the presence of hiatus hernia, and alcohol consumption were all associated with elevated risks for Barrett's esophagus.

CONCLUSIONS

Gastric surgery for benign peptic ulcer disease is not a risk factor for either short- or long-segment Barrett's esophagus. This lack of association between gastric surgery and Barrett's esophagus suggests that reflux of bile without acid is not sufficient to damage the esophageal mucosa.

Temporal associations between coughing or wheezing and acid reflux in asthmatics

BACKGROUND AND AIMS

The pulmonary symptoms of patients with lung disease may be ascribed to gastro-oesophageal reflux although a causal relationship between acid reflux and coughing or wheezing has not been proved. Does cough cause reflux or does reflux cause cough? The aim of this study was to evaluate 24 hour oesophageal pH tracings of asthmatics with gastro-oesophageal reflux to determine the temporal association between acid reflux and coughing or wheezing.

METHODS

The oesophageal tracings of 128 asthmatics from the outpatient clinics who underwent oesophagogastroduodenoscopy, oesophageal manometry, and 24 hour oesophageal pH monitoring were analysed. Three possible temporal relationships between the occurrence of acid reflux and the occurrence of coughs or wheezes were evaluated: (1) pulmonary symptoms preceding reflux; (2) reflux preceding pulmonary symptoms; and (3) unrelated occurrence of both events.

RESULTS

Of 128 asthmatics, 53 recorded five or more coughs and 19 recorded three or more wheezes during the 24 hour recording period. Mean acid contact time was similar in asthmatics with and without pulmonary symptoms (12.2 (1.2)% v 10.4 (0.6)%). Of all coughs and wheezes, 46% and 48%, respectively, were associated with acid reflux. For the individual asthmatic, the likelihood of reflux induced coughing increased as the number of coughs increased.

CONCLUSIONS

Half of all coughs and wheezes in asthmatics are associated with acid reflux into the oesophagus. While an occasional coughing episode can lead to reflux, it is rather the reflux episode in the vast majority of instances that leads to cough.

Reflux symptoms are associated with psychiatric disease

AIMS

To evaluate the frequency of reflux symptoms in patients with a diagnosed psychiatric disorder and to assess potential risk factors for symptom occurrence.

METHODS

The presence of reflux symptoms was compared between a case population of 94 psychiatric patients and a control population of 198 non-psychiatric patients.

RESULTS

Heartburn, exercise-induced heartburn, cough and dysphagia were all reported significantly more frequently by subjects with psychiatric disorders than by control subjects. The presence of any psychiatric diagnosis exerted an increased risk for both heartburn (odds ratio, 2.71; 95% confidence interval, 1.01-7.30) and exercise-induced heartburn (3.34; 1.12-9.96). The type of psychiatric disorder, the type of psychotropic medication and the lifestyle did not influence the presence of reflux symptoms.

CONCLUSIONS

Reflux symptoms occur more frequently in patients with than without a diagnosed psychiatric disorder. The reflux symptoms are not associated with any specific type of medication and may reflect a generally reduced threshold for or distorted perception of symptoms.

Step-down management of gastroesophageal reflux disease

BACKGROUND & AIMS

As the economic burden of gastroesophageal reflux disease (GERD) is largely weighted to maintenance as opposed to initial therapy, switching from more potent to less expensive medication once symptoms are alleviated (step-down therapy) may prove to be most cost-effective. This study aimed to prospectively evaluate the feasibility of step-down therapy in a cohort of patients with symptoms of uncomplicated GERD.

METHODS

Patients whose GERD symptoms were alleviated by proton pump inhibitors (PPIs) were recruited from outpatient general medicine clinics. After baseline demographic and quality of life information were obtained, PPIs were withdrawn from subjects in a stepwise fashion. Primary outcome was recurrence of symptoms during follow-up that required reinstitution of PPIs. Secondary outcomes included changes in quality of life and overall cost of management. Predictors of nonresponse to step-down were assessed.

RESULTS

Seventy-one of 73 enrolled subjects completed the study. Forty-one of 71 (58%) were asymptomatic off PPI therapy after 1 year of follow-up. Twenty-four of 71 (34%) required histamine 2-receptor antagonists, 5/71 (7%) prokinetic agents, 1/71 (1%) both, and 11/71 (15%) remained asymptomatic without medication. Quality of life did not significantly change, whereas management costs decreased by 37%. Multivariable analysis revealed younger age and a dominant symptom of heartburn to predict PPI requirement.

CONCLUSIONS

Step-down therapy is successful in the majority of patients and can decrease costs without adversely affecting quality of life.

No association between gallstones and gastroesophageal reflux disease

OBJECTIVES

Gallstones and hiatal hernia reportedly have been linked to similar dietary factors prevalent in western countries, and patients with cholelithiasis or previous cholecystectomy have been reported to have more duodenogastric reflux than healthy controls. Nonetheless, the contribution of duodenogastric reflux to the development of gastroesophageal reflux disease (GERD) remains controversial. The present study was aimed to assess the association between gallstone disease and GERD.

METHODS

Outpatients from general medical clinics who underwent upper GI endoscopy and abdominal ultrasonography were recruited into a case-control study. A case population of 790 patients with various grades of GERD was compared to a control population of 407 patients without GERD. In a multivariate logistic regression, the presence of GERD served as the outcome variable, whereas the presence of gallstones, hiatal hernia, social habits, and demographic characteristics served as predictor variables.

RESULTS

No associations were found between the presence of cholelithiasis or previous cholecystectomy and GERD or between the presence of cholelithiasis or previous cholecystectomy and hiatal hernia. The severity of GERD also remained unaffected by the presence of gallstones. The occurrence of GERD was influenced only by hiatal hernia (odds ratio [OR] = 3.15, 95% CI = 2.44-4.08), alcohol consumption (OR = 1.47, CI = 1.08-1.99), and not by cholelithiasis (OR = 1.02, CI = 0.68-1.51), or cholecystectomy (OR = 0.90, CI = 0.64-1.28). The frequency of GERD among hiatus hernia patients with gallstones (437/592 = 74%) was similar to the frequency of GERD among hiatus hernia patients without gallstones (168/220 = 76%, p = 0.516).

CONCLUSIONS

Neither cholelithiasis nor cholecystectomy poses a risk for the occurrence of GERD or hiatal hernia. Gallstone disease does not seem to influence the integrity of the esophageal mucosa through GERD.

Hospitalization with respiratory disease following hiatal hernia and reflux esophagitis in a prospective, population-based study

PURPOSE

Hiatal hernia and reflux esophagitis have been associated with respiratory manifestations, though the temporal sequence of this relationship is uncertain. This study examined prospectively the relationship of hiatal hernia and reflux esophagitis with respiratory outcomes in a representative sample of the United States population.

METHODS

6928 participants in the first National Health and Nutrition Examination Survey, a population-based sample initially examined in 1971-1975, who were hospitalized during follow-up through 1992-1993 composed the study population. The relationship between hiatal hernia and reflux esophagitis hospitalization and a subsequent hospitalization with respiratory outcomes was measured in persons free of respiratory disease at baseline and at first hospitalization.

RESULTS

Multivariable survival analysis showed higher rates of hospitalization with any respiratory diagnosis [rate ratio (RR) = 1.4, 95% confidence interval (CI) 1.2-1.7] in persons with preceding hiatal hernia or reflux esophagitis hospitalization. Individually, rate ratios of pharyngitis (RR = 5.6, CI 2.0-15.7), tonsillitis (RR = 8.0, CI 2.5-25.8), bronchitis (RR = 1.8, CI 1.2-2.7), pneumonia (RR = 1.3, CI 1.0-1.7), emphysema (RR = 2.9, CI 1.5-5.5), asthma (RR = 2.1, CI 1.1-4.2), bronchiectasis (RR = 6.2, CI 1.1-34.3), and empyema or abscess (RR = 7.4, CI 1.3-42.3) were all higher following hiatal hernia and reflux esophagitis. Rate ratios were similar when reflux esophagitis and hiatal hernia were examined separately.

CONCLUSIONS

A prior hiatal hernia or reflux esophagitis hospitalization increased risk of respiratory disease hospitalization.

Period- and cohort-age contours of deaths from gastric and duodenal ulcer in New York 1804-1998

OBJECTIVES

Mortality data of peptic ulcer are mostly national and limited to the 20th century. The New York City data from 1804 have therefore been examined by both year of death and year of birth (cohort analysis), to consider whether the increases and subsequent decreases in deaths from gastric, followed by duodenal ulcer, can be attributed to Helicobacter pylori.

METHODS

The annual mortality reports of New York City described gastric ulcer from 1838 and duodenal ulcer from 1931. The age-specific death rates per 100,000 population were calculated in 10-yr periods both by year of death and by year of birth for each disease according to age and sex.

RESULTS

For gastric ulcer the period-of-death-age contours from the 1850s to the 1990s showed an increase to a mid-19th century plateau, but the cohort-age contours revealed a peak mortality for those born in the 1870s. Women born between about 1770 and 1880 showed a faster increase in mortality. For duodenal ulcer the period of birth contours showed a decline from a peak for those born in the 1880s and 1890s, with no sex difference.

CONCLUSIONS

This urban study with data regarding deaths from gastric ulcer registered from 1838 and in those born from the 1770s, revealed by cohort analysis a peak in the 1870s, and for duodenal ulcer in the 1880s, comparable to national data worldwide. These time changes in fatalities are compatible with a change in the environment of children born in these decades, as, for example infection by a pathogenic strain of H. pylori.

Risk factors of oesophagitis in arthritic patients

BACKGROUND

The risk factors that precipitate the occurrence of oesophageal mucosal injury in patients on continuous nonsteroidal anti-inflammatory drug (NSAID) therapy are unknown.

METHODS

Outpatients who regularly consumed NSAIDs for osteoarthritis were recruited from a rheumatology clinic into a prospective case-control study. All patients answered a structured interview and underwent upper gastrointestinal endoscopy.

RESULTS

Of 450 eligible patients, 195 (43%) consented to be interviewed and undergo upper gastrointestinal endoscopy. Oesophagitis was diagnosed in 41 of these 195 patients (21%). The occurrence of gastric or duodenal ulcer in individual patients did not predict the concomitant damage of the oesophageal mucosa. Young age (odds ratio: 1.79 per decade of life; 95% confidence interval: 1.11-2.86) and hiatus hernia (odds ratio: 3.72; 95% confidence interval: 1.63-8.49) both increased the risk of developing oesophagitis. When questioned, all oesophagitis patients revealed at least one gastrointestinal symptom, heartburn being named most frequently (odds ratio: 4.78; 95% confidence interval: 2.04-11.17). The type of anti-inflammatory medication, the use of alcohol and the use of nicotine were not associated with any significant risk for erosive oesophagitis.

CONCLUSIONS

Patients on chronic NSAID therapy for rheumatological disease suffer frequently from erosive oesophagitis. While the risk may be higher in patients with a pre-existing tendency for gastro-oesophageal reflux, any concomitant history of NSAID-induced peptic ulcer disease does not add to the risk. Erosive oesophagitis should be considered especially in patients on NSAIDs who complain of heartburn.

Function and interactions of integrins

Integrins are heterodimeric cell adhesion molecules that link the extracellular matrix to the cytoskeleton. The integrin family in man comprises 24 members, which are the result of different combinations of 1 of 18 alpha- and 1 of 8 beta-subunits. Alternative splicing of mRNA of some alpha- and beta-subunits and postranslational modifications of integrin subunits further increase the diversity of the integrin family. In their capacity as adhesion receptors that organize the cytoskeleton, integrins play an important role in controlling various steps in the signaling pathways that regulate processes as diverse as proliferation, differentiation, apoptosis, and cell migration. The intracellular signals that lead to these effects may be transduced via cytoplasmic components, which have been identified as integrin-binding proteins in yeast two-hybrid screens and which could mediate the coupling of integrins to intracellular signaling pathways. In this review an overview is given of the function and ligand-binding properties of integrins as well as of proteins that associate with integrins and may play a role in their signaling function.

When William of Ockham meets Thomas Bayes: finding a few diagnoses among a great many symptoms

Bayes' formula is a means to estimate disease probability based on the presence of symptoms and the outcome of clinical tests. The probability helps to decide among competing diagnostic options. If, however, several diseases present with similar symptoms, they may appear equally probable, and Bayes' formula will fail as an aid to reach a diagnostic decision. The aim of this study is to show how a merger of Bayes' principle with that of Ockham can help to decide in favour of one diagnosis among multiple, seemingly equally probable diagnostic hypotheses. The hypotheses are compared to each other with respect to those tests and symptoms which they fail to explain. The unexplained tests and symptoms are used to estimate the probabilities for a set of secondary diagnoses that match each one of the primary diagnoses. The more likely a secondary diagnosis appears, the less likely its corresponding primary diagnosis will remain as the sole diagnosis to explain all the clinical findings. Even without a detailed calculation, the proposed concept of using unexplained tests and symptoms to rate competing differential diagnoses could help the clinician to select the most probable diagnosis.

The hemidesmosomal protein bullous pemphigoid antigen 1 and the integrin beta 4 subunit bind to ERBIN. Molecular cloning of multiple alternative splice variants of ERBIN and analysis of their tissue expression

The bullous pemphigoid antigen 1 (eBPAG1) is a constituent of hemidesmosomes (HDs), cell-substrate adhesion complexes in stratified epithelia. Although its COOH terminus interacts with intermediate filaments, its NH(2) terminus is important for its recruitment into HDs. To identify proteins that interact with the NH(2) terminus of human eBPAG1, we performed a yeast two-hybrid screen, which uncovered a protein belonging to the LAP/LERP (for LRR and PDZ domain) protein family with 16 NH(2)-terminal leucine-rich repeats and a COOH-terminal PDZ domain. The gene for this LAP/LERP protein comprises at least 26 exons located on the long arm of chromosome 5. In most human tissues, several transcripts were detected differing in the coding region situated upstream of or within the PDZ domain. One of the encoded variants was found to correspond to the recently described protein ERBIN. In yeast and in vitro binding experiments, ERBIN was shown to interact not only with eBPAG1 but also with the COOH-terminal region of the cytoplasmic domain of the integrin beta4 subunit, another component of HDs. Antibodies raised against the COOH terminus showed that ERBIN is expressed in keratinocytes. In transfected epithelial cells the protein, however, was not localized in HDs but was either diffusely distributed over the cytoplasm or concentrated at the basolateral plasma membrane. Because ERBIN had been shown previously to interact with the transmembrane tyrosine kinase receptor Erb-B2, which in turn associates with the integrin beta4 subunit, we suggest that ERBIN provides a link between HD assembly and Erb-B2 receptor signaling.

Cause of death in patients with inflammatory bowel disease

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) can both result in disease-related mortality. The aim of the present study was to analyze the comorbid medical conditions that contribute to death of patients with inflammatory disease.

METHODS

The United States' vital statistics offer the opportunity to study causes of death broken down by primary and contributing secondary conditions. Deaths from UC and CD were retrieved from the 1991-1996 data files of the National Center for Health Statistics. The strengths of individual associations between each comorbid condition and UC or CD were expressed as proportional mortality ratios, adjusted to the age-, gender-, and race-distribution of the general population.

RESULTS

Deaths from UC and CD were found to be associated with a similar set of comorbid conditions and complications. Shock, volume depletion, protein/calorie malnutrition, and anemia were the most frequent comorbid conditions in the group of nutritional, fluid, and electrolyte disturbances. Both diseases were frequently associated with peritonitis and septicemia. Lastly, a large number of deaths were associated with complications following medical and surgical interventions.

CONCLUSIONS

Deaths due to inflammatory bowel disease appear to be related to complications from multiple medical interventions and surgical procedures. In managing inflammatory bowel disease, the physician must keep in mind the potential for complications that may be associated with aggressive treatment.

Gastroesophageal reflux disease is a risk factor for laryngeal and pharyngeal cancer

OBJECTIVE

Gastroesophageal reflux disease (GERD) is a proposed risk factor for developing laryngeal and pharyngeal cancers. No controlled study has examined this association.

METHODS

A case-control-study was performed using the computerized hospitalization and outpatient databases of the US Department of Veterans Affairs. All patients, who were veterans, had been identified as being hospitalized with laryngeal or pharyngeal during 1991 to 1997. In addition, all persons diagnosed with laryngeal or pharyngeal cancer in 1999 in the outpatient files were identified. From the same patient populations, four nonmatched control subjects were randomly assigned for each case. The medical history for cases and controls was retrospectively searched for GERD diagnoses, tobacco use, and alcohol dependence. Multivariable logistic regression analyses were performed to assess the risk factors for laryngeal and pharyngeal cancers.

RESULTS

A total of 8,228 hospitalized patients with laryngeal cancers and 1,912 with pharyngeal cancers were compared to 32,912 and 7,648 hospitalized controls, while 9,292 outpatients with laryngeal cancer and 2,769 outpatients with pharyngeal cancer were compared with 37,168 and 11,076 outpatient controls without cancer. Among hospitalized persons, the prevalence of GERD was higher among patients with laryngeal cancer (8.9 vs 4.0%, p < 0.0001) and pharyngeal cancer (6.2 vs 3.8%, p < 0.0001). In a multivariable logistic regression analysis that was controlled for age, gender, ethnicity, smoking, and alcohol, GERD was associated with an adjusted odds ratio (OR) of 2.40 for laryngeal cancer among hospitalized patients (95% CI 2.15-2.69, p < 0.0001) and an adjusted OR of 2.38 (95% CI 1.87-3.02, p < 0.0001) for pharyngeal cancer. For outpatients, GERD was associated with an adjusted OR = 2.31 (95% CI 2.10-2.53) for laryngeal cancer and adjusted OR = 1.92 (95% CI 1.72-2.15).

CONCLUSIONS

Among US veterans, the risk for laryngeal or pharyngeal cancers is modestly increased in the presence of GERD. This effect seems to be independent of age, gender, smoking, and alcohol intake.