Healthcare resource utilization in the management of oesophageal adenocarcinoma

OBJECTIVE

To study the natural history of oesophageal adenocarcinoma in terms of utilization of the healthcare resources and associated medical costs.

METHODS

All 29 patients treated at the University of New Mexico Health Center between 1 January 1992 and 1 December 1998 for an oesophageal adenocarcinoma were included in the study. For each individual patient, all medical resources utilized, facility costs, and physician fees were retrieved from the computerized databases of the collection departments.

RESULTS

During the progress of the disease, the same type of diagnostic or therapeutic procedure became necessary a number of times, and patients underwent, on average, three (range one to eight) upper gastrointestinal endoscopies, five (range one to 11) computerized tomography scans, 35 (five to 143) X-ray examinations, and 28 (three to 46) radiation therapies or 39 (10 to 74) chemotherapies. The large variation in the numbers of resources utilized was also reflected by a corresponding variation in total healthcare costs. The mean cost per patient was $48 127, ranging between $13 454 and $139 721. Facility costs comprised 88% of all costs compared to physician fees which comprised 12%. The largest cost items, in declining order, were physician encounters ($16 916), radiation plus chemotherapy ($9909 plus $4891, respectively), and pharmacy prescriptions ($7565).

CONCLUSIONS

The prolonged disease process and the many diagnostic and therapeutic procedures result in complications, side-effects, inconclusive tests, or failed therapies that all markedly increase the use of healthcare resources. Because such outcomes are the rule rather than the exception, the management of oesophageal adenocarcinoma is expensive.

The comorbid occurrence of other diagnoses in patients with ulcerative colitis and Crohn's disease

OBJECTIVES

The comorbidity between inflammatory bowel disease (IBD) and other diagnoses may help to shed light on the etiology and pathophysiology of IBD. The US Vital Statistics offer the opportunity to study causes of death broken down by comorbid disease associations. The aim of this study was to analyze the presence of comorbid conditions in persons who died from ulcerative colitis or Crohn's disease.

METHODS

The numbers of deaths from ulcerative colitis and Crohn's disease were retrieved from the computerized 1991-1996 data files of the National Center for Health Statistics. Comorbid associations between other diagnosis and ulcerative colitis or Crohn's disease were expressed as age-, gender-, and race-standardized proportional mortality ratios.

RESULTS

Ulcerative colitis and Crohn's disease showed, in general, similar patterns of comorbidity. Both diseases were associated with similar sets of GI complications, such as intestinal obstruction and stasis, mucosal inflammation and infection, vascular complications, and complications related to fistula and abscess formation. Extraintestinal complications of both IBD involved disorders of the hepatobiliary system, urinary system, and various coagulopathies. Ulcerative colitis alone was found to be associated with Hirschsprung's disease and schizophrenia, whereas Crohn's disease alone was found to be related with osteoporosis and amyloidosis.

CONCLUSIONS

No completely unexplained or hitherto undescribed association was revealed. The numerous intestinal and extraintestinal complications associated with IBD serve as a reminder of the systemic nature and the resultant clinical severity of both ulcerative colitis and Crohn's disease.

Comorbid occurrence of liver and pancreas disease in United States military veterans

OBJECTIVE

The clinical epidemiology of the comorbidity between liver and pancreas disease is unknown. The Patient Treatment File of the Department of Veterans Affairs contains the computerized records of all inpatients treated in 172 Department of Veterans Affairs hospitals distributed throughout the United States. This large database offers a unique opportunity to study the epidemiology of liver-pancreas comorbidity (LPC).

METHODS

In a case-control study, 6,393 LPC cases were compared to 34,513 controls with alcoholic liver disease and liver cirrhosis alone and 68,038 controls without liver or pancreas disease. Multivariate logistic regression analysis was used to assess the joint influence of multiple risk factors on the occurrence of LPC.

RESULTS

LPC occurred in 15.6% of patients with alcoholic liver disease and liver cirrhosis identified in the Patient Treatment File between 1990 and 1993. Compared to controls with liver disease alone, LPC cases were characterized by younger age (odds ratio = 0.88 per age decade, CI = 0.86-0.90) and African American (2.33, 2.18-2.48) or Hispanic (1.24, 1.12-1.38) ethnicity. Compared to controls with neither liver nor pancreas disease, LPC cases were characterized by male gender (1.67, 1.28-2.17), African American (1.41, 1.32-1.50) or Hispanic (2.04, 1.82-2.30) ethnicity, more frequent history of alcoholism (29.5, 26.7-32.6), and being divorced (1.35, 1.26-1.44).

CONCLUSIONS

Comorbidity of liver and pancreas disease is relatively common in the veteran population. Such patients are more frequently divorced and of African American or Hispanic ethnicity, and present with a history of excessive alcoholism at a relatively young age.

Truncated typeXVII collagen expression in a patient with non-herlitz junctional epidermolysis bullosa caused by a homozygous splice-site mutation

SUMMARY

Type XVII collagen (180-kDa bullous pemphigoid antigen) is a structural component of hemidesmosomes. Mutations in the type XVII collagen gene (COL17A1) have been established to be the molecular basis of non-Herlitz junctional epidermolysis bullosa (JEB-nH), an inherited skin blistering disorder. Here we report for the first time truncated type XVII collagen expression, caused by homozygosity for a COL17A1 donor splice-site mutation (4261+1 g --> c), which was identified by PCR amplification on genomic DNA. By RT-PCR and sequencing of cDNA derived from mRNA from the patient's cultured keratinocytes, we provide evidence of cryptic splicing and exon skipping, most abundantly of exon 52. JEB-nH patients with COL17A1 splice-site mutations resulting in an exon skip often have no immunologically detectable type XVII collagen. However, in our patient with the generalized atrophic benign epidermolysis bullosa subtype, a small amount of type XVII collagen was detectable in the skin, and immunoblotting of cultured keratinocytes revealed that the 180-kDa protein was 10 kDa shorter. We hypothesize that the function of this truncated type XVII collagen polypeptide, which is expressed at low levels, is impaired, explaining the JEB-nH phenotype.

Long-term nonsurgical management of Barrett's esophagus with high-grade dysplasia

BACKGROUND & AIMS

Surgical resection of the esophagus is frequently recommended for Barrett's high-grade dysplasia (HGD) without cancer.

METHODS

During a 20-year period, patients were diagnosed and observed through an organized surveillance program at the Hines Veterans Affairs Hospital. The program was supported by Hines VA and organized and managed by 2 endoscopists using preestablished endoscopic criteria.

RESULTS

Barrett's esophagus was diagnosed in 1099 patients, and 36,251 esophageal mucosal specimens were reviewed. Seventy-nine of 1099 patients (7.2%) initially had HGD (34 prevalent) or subsequently developed HGD (45 incident) without evidence of cancer. Of the 75 HGD patients who remained without detectable cancer after the 1 year of intensive searching, 12 developed cancer (16%) during a mean 7.3-year surveillance period: 11 of the 12 who were compliant were considered cured with surgical or ablation therapy. Cancer did not develop in the remaining 63 HGD patients during the surveillance period.

CONCLUSIONS

HGD without cancer in Barrett's esophagus follows a relatively benign course in the majority of patients. In the patients who eventually progress to cancer during regular surveillance, surgical resection is curative. Surveillance endoscopies with biopsy is a valid and safe follow-up strategy for Barrett's patients who have HGD without cancer.

The interaction of plectin with actin: evidence for cross-linking of actin filaments by dimerization of the actin-binding domain of plectin

Plectin is a major component of the cytoskeleton and is expressed in a wide variety of cell types. It plays an important role in the integrity of the cytoskeleton by cross-linking the three filamentous networks and stabilizing cell-matrix and cell-cell contacts. Sequence analysis showed that plectin contains a highly conserved actin-binding domain, consisting of a pair of calponin-like subdomains. Using yeast two-hybrid assays in combination with in vitro binding experiments, we demonstrate that the actin-binding domain of plectin is fully functional and preferentially binds to polymeric actin. The sequences required for actin binding were identified at the C-terminal end of the first calponin homology domain within the actin-binding domain of plectin. We found that the actin-binding domain of plectin is able to bundle actin filaments and we present evidence that this is mediated by the dimerization of this domain. In addition we also show that plectin and another member of the plakin family, dystonin, can heterodimerize by their actin-binding domains. We propose a new mechanism by which plectin and possibly also other actin-binding proteins can regulate the organization of the F-actin network in the cell.

Is there a link between cervical inlet patch and Barrett's esophagus?

BACKGROUND

Heterotopic gastric-type mucosa occurs as a flat island or islands of red mucosa in the proximal third of the esophagus where it gives rise to the "cervical inlet patch" (CIP). The aim of the present study was to delineate the clinical epidemiology of the CIP, especially its possible relationship to Barrett's esophagus.

METHODS

A case-control study compared 53 case subjects with CIP and 4882 control subjects without CIP. In a multivariate logistic regression, the presence of CIP was chosen as the outcome variable, whereas demographic characteristics, social habits, and presence of other endoscopic diagnoses served as predictor variables.

RESULTS

The prevalence of CIP was 1.1%. Its presence was associated with hiatal hernia (odds ratio 2.26: 95% CI [1.12, 4.56]) gastric ulcer (2.93: 95% CI [1.34, 6.40]) and Barrett's esophagus (4.41: 95% CI [2.31, 8.41]).

CONCLUSIONS

The coincidence of the cervical inlet patch and Barrett's esophagus could suggest a shared embryonic etiology.

Epithelial development and differentiation in the mammary gland is not dependent on alpha 3 or alpha 6 integrin subunits

In the mammary gland, both laminin and integrins have been shown to be required for normal ductal morphogenesis during development in vivo, and for functional differentiation in culture models. Major integrin receptors for laminins in the mammary gland are alpha 3 beta 1, alpha 6 beta 1, and alpha 6 beta 4. However, the specific subunits that contribute to laminin-mediated mammary cell function and development have not been identified. In this study, we use a genetic approach to test the hypothesis that laminin-binding integrins are required for the function of the mammary gland in vivo. Rudiments of embryonic mammary gland were shown to develop in the absence of these integrin subunits. Postnatal development of the mammary gland was studied in integrin null tissue that had been transplanted into the mammary fat pads of syngeneic hosts. In mammary epithelium lacking alpha 6 integrin, the beta 4 subunit was not apparent and hemidesmosome formation was only rudimentary. However, despite this deficiency, normal ductal morphogenesis and branching of the mammary gland occurred and myoepithelial cells were distributed normally with respect to luminal cells. Mammary alveoli devoid of alpha 3 or alpha 6 integrin formed in pregnancy and were histologically and functionally identical to those in wild-type mammary gland. The tissue underwent full morphological differentiation, and the epithelial cells retained the ability to synthesize beta-casein. This work demonstrates that mammary tissue genetically lacking major laminin-binding integrin receptors is still able to develop and function.

Reduced symptoms and need for antisecretory therapy in veterans 3 years after Helicobacter pylori eradication with ranitidine bismuth citrate/amoxicillin/clarithromycin

OBJECTIVE

The most effective combination therapy to eradicate Helicobacter pylori has not yet been found. The perfect combination would be effective, relatively free of side effects, and easy to comply with. We studied a 14-day course of three medications taken twice daily by H. pylori-infected patients who were enrolled in the outpatient Veterans Affairs (VA) clinics. The two major objectives were 1) to determine the effectiveness of the combination therapy and 2) to determine the compliance of patients in a VA population.

METHODS

Fifty-two male patients were identified with H. pylori infection by positive CLO (Rapid Urease Test) test, positive Giemsa stain, or positive serology. Active infection was confirmed by a positive 13C urea breath test (UBT). Patients were treated for 14 days with open-label triple-combination therapy of ranitidine bismuth citrate (RBC; 400 mg b.i.d.), amoxicillin (1000 mg b.i.d.), and clarithromycin (500 mg b.i.d.). Successful eradication of H. pylori was confirmed by repeat UBT at 6-8 wk after the final dose of therapy.

RESULTS

Of the 52 enrolled patients, 49 (94.2%) met the criteria for successful completion of the study (per protocol analysis based on compliance with at least 80% of medication and performance of both UBTs). Of the three patients who did not successfully complete, one was cured (after 6 days of treatment), and two remained infected (after 3 days and 9 days of treatment). Of the 49 completed patients, 45 (91.8%) were cured, and four remained infected. Overall, regardless of compliance (intent-to-treat analysis), 46 of the 52 (88.4%) patients had documented cure of H. pylori infection as determined by the posttreatment UBT. By 3 yr after H. pylori eradication, two of 15 (13.3%) patients who were not on baseline medications had developed the need for antisecretory therapy, but 18 of 31 (58.1%) who were on baseline medications were able to stop therapy. Thus, at 3 yr, successful H. pylori eradication decreased the need for antisecretory therapy from 67.4% of the H. pylori-infected population to 43% of the H. pylori-eradicated population. The effect of H. pylori eradication in improving symptoms at 3 yr was statistically significant in both the ulcer population and the nonulcer population. Adverse events were mild, and included diarrhea (26 patients), bad taste in mouth (24 patients), nausea/upset stomach (nine patients), and headache (two patients). The diarrhea was self-limiting in 25 of the 26 patients. Only two patients discontinued medication because of adverse events.

CONCLUSION

The RBC/amoxicillin/clarithromycin combination was, in our VA population, an easily complied with, highly effective, and safe triple therapy with a 90% H. pylori eradication rate. Successful eradication of H. pylori leads to a dramatic decrease in upper-gut symptoms and decreased need for antisecretory therapy.

Structural and functional aspects of filamins

Filamins are a family of high molecular mass cytoskeletal proteins that organize filamentous actin in networks and stress fibers. Over the past few years it has become clear that filamins anchor various transmembrane proteins to the actin cytoskeleton and provide a scaffold for a wide range of cytoplasmic signaling proteins. The recent cloning of three human filamins and studies on filamin orthologues from chicken and Drosophila revealed unexpected complexity of the filamin family, the biological implications of which have just started to be addressed. Expression of dysfunctional filamin-A leads to the genetic disorder of ventricular heterotopia and gives reason to expect that abnormalities in the other isogenes may also be connected with human disease. In this review aspects of filamin structure, its splice variants, binding partners and biological function will be discussed.

Occupational mortality from inflammatory bowel disease in the United States 1991-1996

OBJECTIVE

The occupational distribution of inflammatory bowel disease (IBD) may help to shed light on its yet unknown etiology. The U.S. vital statistics offer the opportunity to study cause of death by occupation and industry.

METHODS

The numbers of deaths from Crohn's disease and ulcerative colitis were retrieved from the computerized 1991-1996 data files of the National Center for Health Statistics. Deaths were grouped by gender, ethnicity, disease type, occupation, and industry. Mortality by occupation and industry were expressed as proportional mortality ratio (PMR), adjusted for gender and ethnicity.

RESULTS

Between 1991 and 1996, 2399 subjects died from Crohn's disease and 2419 subjects died from ulcerative colitis. Significant correlations were found between the PMR values of ulcerative colitis and Crohn's disease regarding their distribution by occupation, r = 0.36 and p < 0.05, as well as by industry, r = 0.37, p < 0.01. IBD mortality by occupation was significantly reduced among farmers (PMR: 70, 95% confidence interval [CI]: 42-97), mining machine operators (31, 95% CI: 0-74), and laborers (71. 95% CI: 45-98). A nonsignificant increase was found among sales persons (117, 95% CI: 95-139) and secretaries (122, 95% CI: 83-161). IBD mortality by industry was significantly reduced in agricultural production of livestock (39, 95% CI: 1-78), mining (46, 95% CI: 9-83), grocery stores (55, 95% CI: 17-94), and work in private households (64, 95% CI: 30-97). A nonsignificant increase was found in food production (128, 95% CI: 74-182), investment and insurance business (137, 95% CI: 77-198), and administration (122, 95% CI: 81-163).

CONCLUSIONS

IBD mortality is low in occupations associated with manual work and farming and relatively high in sedentary occupations associated with indoor work. Crohn's disease and ulcerative colitis show a similar distribution.

Occupational mortality from inflammatory bowel disease in the United States 1991-1996

OBJECTIVE

The occupational distribution of inflammatory bowel disease (IBD) may help to shed light on its yet unknown etiology. The U.S. vital statistics offer the opportunity to study cause of death by occupation and industry.

METHODS

The numbers of deaths from Crohn's disease and ulcerative colitis were retrieved from the computerized 1991-1996 data files of the National Center for Health Statistics. Deaths were grouped by gender, ethnicity, disease type, occupation, and industry. Mortality by occupation and industry were expressed as proportional mortality ratio (PMR), adjusted for gender and ethnicity.

RESULTS

Between 1991 and 1996, 2399 subjects died from Crohn's disease and 2419 subjects died from ulcerative colitis. Significant correlations were found between the PMR values of ulcerative colitis and Crohn's disease regarding their distribution by occupation, r = 0.36 and p < 0.05, as well as by industry, r = 0.37, p < 0.01. IBD mortality by occupation was significantly reduced among farmers (PMR: 70, 95% confidence interval [CI]: 42-97), mining machine operators (31, 95% CI: 0-74), and laborers (71. 95% CI: 45-98). A nonsignificant increase was found among sales persons (117, 95% CI: 95-139) and secretaries (122, 95% CI: 83-161). IBD mortality by industry was significantly reduced in agricultural production of livestock (39, 95% CI: 1-78), mining (46, 95% CI: 9-83), grocery stores (55, 95% CI: 17-94), and work in private households (64, 95% CI: 30-97). A nonsignificant increase was found in food production (128, 95% CI: 74-182), investment and insurance business (137, 95% CI: 77-198), and administration (122, 95% CI: 81-163).

CONCLUSIONS

IBD mortality is low in occupations associated with manual work and farming and relatively high in sedentary occupations associated with indoor work. Crohn's disease and ulcerative colitis show a similar distribution.

Medical diagnoses and procedures associated with clostridium difficile colitis

OBJECTIVES

The aim of this study was to examine the associations of Clostridium difficile colitis with other comorbid conditions and procedural interventions among hospitalized patients.

METHODS

The Patient Treatment File of the Department of Veterans Affairs contains the computerized records of all inpatients treated in 172 Veterans Affairs hospitals distributed throughout the United States. The computerized medical records of 15,091 cases with C. difficile colitis and 61,931 controls without the diagnosis were extracted from the annual files between 1993 and 1998. In a multivariable logistic regression, the occurrence of C. difficile colitis served as outcome variable, whereas the occurrences of other diagnoses or procedures served as predictor variables.

RESULTS

The total numbers of diagnoses in the case and control group were 136,840 and 465,972, respectively. The numbers of procedures were 75,479 and 129,612, respectively. C. difficile colitis was significantly associated with HIV infection, candidiasis, malignant neoplasm and chemotherapy, malnutrition, pneumonia, aspiration pneumonitis, intestinal obstruction, diverticulitis, renal failure, urinary tract infection, decubitus, and osteomyelitis. Interventional procedures involving the respiratory tract, bone marrow biopsy, arterial and venous catheterization, urinary catheterization, dialysis, gastrostomy tube, and physical therapy were also frequently associated with the development of C. difficile colitis.

CONCLUSIONS

These associations reflect the influence of causal relationships (such as the use of antibiotics and chemotherapy), an increased risk of exposure to C. difficile among immobilized bedridden patients with chronic disease states, or a general system failure in patients with end-stage disease. Knowledge of such associations could help to alert physicians to an increased risk of C. difficile colitis among particular groups of susceptible patients.

Cost-effectiveness of endoscopy in irritable bowel syndrome

BACKGROUND

It is unknown to what extent at what expense flexible sigmoidoscopy and colonoscopy add to the diagnosis of irritable bowel syndrome (IBS). The aim of the study was to assess the incremental cost-effectiveness of endoscopic procedures in the workup for IBS.

METHODS

Using the Bayes formula, we calculated the increase in diagnostic certainty for a consecutive number of tests. We also calculated the incremental cost-effectiveness ratio, which corresponds to the test costs divided by the increment in diagnostic certainty.

RESULTS

The diagnosis of IBS can be established with a relatively high probability of more than 80% relying on relatively inexpensive and noninvasive tests only. Flexible sigmoidoscopy or colonoscopy constitute the most costly portion of any workup for IBS, which amounts to 50% to 75% of the overall costs. Because of their high incremental cost-effectiveness ratio, endoscopic procedures should not be used at the beginning of the diagnostic workup. This outcome of the analysis remains largely unaffected within reasonable ranges of the sensitivity and specificity of various tests.

CONCLUSIONS

In the diagnosis of IBS, inexpensive, noninvasive tests should be used first to rule out other diagnoses. Despite their high incremental cost-effectiveness ratio, flexible sigmoidoscopy and colonoscopy are indicated when a serious organic disease is reasonably likely and needs to be ruled out.

Walking and chewing reduce postprandial acid reflux

BACKGROUND

Gastro-oesophageal reflux is worse after meals, and antacids are usually consumed after dietary indiscretion.

AIM

To investigate whether walking or gum chewing affect meal-induced gastro-oesophageal reflux.

METHODS

The study population comprised 12 case subjects with gastro-oesophageal reflux disease and 24 healthy controls. Each subject was studied using pH-metry for 5 h on 3 separate days. After baseline recording of pH for 1 h, all subjects were fed a standard breakfast over a 20-min period. On one of the days, oesophageal pH was recorded after the 20-min eating period for an additional 4 h in the sitting position. On another day, postprandial oesophageal pH was recorded for the first hour whilst walking, and for 3 subsequent hours whilst sitting. During a third day, oesophageal pH was recorded for the first postprandial hour whilst gum-chewing, followed by 3 h of sitting.

RESULTS

Food intake promoted gastro-oesophageal reflux in case subjects with GERD as well as in healthy controls, although postprandial reflux was more pronounced amongst the refluxers than amongst the controls. Chewing gum for 1 h after the meal reduced the acid contact time in both groups, with a more profound effect in refluxers than in controls. Whilst the beneficial effect of 1-h of gum-chewing lasted for up to 3 h in both groups, the beneficial effect of 1-h of walking was apparent only in refluxers, only to a mild degree, and only for a short duration.

CONCLUSIONS

Chewing gum after a meal helps to reduce postprandial oesophageal acid exposure.

The diagnostic pursuit of gastrointestinal symptoms

The present article attempts to model the reasoning underlying the process of diagnostic workup in a patient with GI symptoms. Diagnostic reasoning consists of two consecutive and repetitive steps. Test procedures help to contract a list of multiple competing diagnoses to one focal diagnosis. In a subsequent step, the focal diagnosis again becomes expanded to a second list of new diagnoses that are more precise than those on the first list. In the process of expansion, the focal diagnosis itself serves as a test with its own sensitivity values to generate the second list of associated diagnoses. The process of contraction and expansion repeats itself, until the focal diagnosis of the last contraction is no longer expansible or until diagnostic knowledge gained from further expansion loses therapeutic relevance. The process of contraction and expansion can be formalized by Bayes' formula.

Risk factors for erosive reflux esophagitis: a case-control study

OBJECTIVES

It is presently not fully understood which risk factors contribute to the occurrence of reflux esophagitis and how such factors might influence the severity of the disease. The aim of this study was to delineate the clinical epidemiology of erosive reflux esophagitis.

METHODS

Outpatients from a medicine and gastroenterology clinic who underwent upper GI endoscopy were recruited into a case-control study. A total of 1,533 patients with and 3,428 patients without endoscopically diagnosed reflux esophagitis were categorized as case and control subjects, respectively. Using multivariate logistic regressions for statistical analysis, the presence of esophageal erosions, ulcers or strictures, served as three separate outcome variables. Demographic characteristics, intake of nonsteroidal anti-inflammatory drugs (NSAIDs), consumption of alcohol and cigarettes, and the presence of hiatus hernia or peptic ulcer served as predictor variables.

RESULTS

Erosive reflux esophagitis tended to occur more frequently in Caucasian male patients. Hiatus hernia was associated with a strong risk for developing esophageal erosions, ulcers, and strictures. Although statistical significance was demonstrated only for esophageal erosions, in all grades of reflux esophagitis alike, gastric and duodenal ulcer exerted a protective influence. Consumption of NSAIDs increased the risk for esophageal ulcers only. Smoking and alcohol were not associated with an increased risk of developing any type of erosive reflux esophagitis.

CONCLUSIONS

The results stress the critical role played by hiatus hernia in all grades of erosive reflux esophagitis. NSAIDs may act through a mechanism of topically induced esophageal injury. Our data also suggest that the presence of either gastric or duodenal ulcer exerts a protective influence against the development of reflux disease.

Dual stimulation of Ras/mitogen-activated protein kinase and RhoA by cell adhesion to fibronectin supports growth factor-stimulated cell cycle progression

In cellular transformation, activated forms of the small GTPases Ras and RhoA can cooperate to drive cells through the G1 phase of the cell cycle. Here, we show that a similar but substrate-regulated mechanism is involved in the anchorage-dependent proliferation of untransformed NIH-3T3 cells. Among several extracellular matrix components tested, only fibronectin supported growth factor-induced, E2F-dependent S phase entry. Although all substrates supported the mitogen-activated protein kinase (MAPK) response to growth factors, RhoA activity was specifically enhanced on fibronectin. Moreover, induction of cyclin D1 and suppression of p21(Cip/Waf) occurred specifically, in a Rho-dependent fashion, in cells attached to fibronectin. This ability of fibronectin to stimulate both Ras/MAPK- and RhoA-dependent signaling can explain its potent cooperation with growth factors in the stimulation of cell cycle progression.

Special review: game theory to analyse management options in gastro-oesophageal reflux disease

This study aims to demonstrate the applicability of linear programming to threshold analysis, using, as an example, patients with new onset of gastro-oesophageal reflux disease (GERD). The choice amongst competing management options is modelled as a decision tree, using threshold analysis, as well as an m x n matrix on an Excel spreadsheet. The different options of medical management correspond to the m rows, whilst the different disease states correspond to the n columns of the matrix. Each number at the intersection of a row and a column represents the outcome associated with that particular combination of management and disease state. The threshold values are calculated by the built-in functions for linear programming of Excel using its Solver tool. Varying the cost estimates in the sensitivity analysis translates into solving a set of different matrices. Threshold analysis provides a formalism to phrase problems of medical decision analysis in a concise fashion.

Sidetracks in the diagnosis of gastrointestinal disease

Patients usually visit a physician for a particular reason, which medicine has termed the "chief complaint." As patients often have more than a single complaint, it is common for physicians to lose focus, get distracted, and venture down a path other than the one toward resolution of the chief complaint--in other words, to get sidetracked. The aim of the present review is to describe the nature of diagnostic sidetracking, why it occurs, mechanisms in action, and means to prevent it. During a regular diagnostic process, the physician's suspicions about a diagnosis advance from broad and general to narrow and specific concepts. Each step in the diagnostic process is potentially driven by its own hypothesis, and each individual hypothesis becomes verified or falsified by pointed questions during the history or by medical tests. If a diagnostic process were to focus on the correct diagnosis that eventually explained the chief complaint, the intersections among the consecutively refined diagnostic concepts would converge toward one specific set, with the final diagnosis located inside the nonzero intersection of all consecutive diagnostic concepts. In a faulty diagnostic process, consecutive diagnostic concepts fail to converge, and the final diagnosis and chief complaint do not intersect. In this regard, the physician has pursued a false path and has become sidetracked. The effects of sidetracking range from minimal to disastrous. Sidetracking can delay diagnosis, delay treatment, and waste resources investigating or treating irrelevant medical problems. To avoid sidetracking, physicians should focus on the main problem, avoid getting involved with complementary solutions to secondary medical problems, and verify repetitively during the diagnostic process the relationship between each current working hypothesis and the patient's major medical problem.

Timing of surgery for enterovesical fistula in Crohn's disease: decision analysis using a time-dependent compartment model

OBJECTIVES

Previous decision analyses of inflam matory bowel diseases (IBD) have used decision trees and Markov chains. Occasionally IBD patients present with medical problems that are difficult or even impossible to phrase in terms of such established decision tools. This article aims to introduce modeling by a time-dependent compartment mode and demonstrate its feasibility for decision analysis in IBD METHODS: A Crohn's disease patient presented with a pelvic abscess and an enterovesical fistula. Being hesitant to operate in an acutely inflamed area, the surgeon recommended that the patient continue antibiotic therapy until the abscess had re solved. The gastroenterologist argued that the patient had already been treated with antibiotics for a prolonged time period and expressed concern that the patient's overall diminished health status would deteriorate by further delay of surgery. The occurrence of fistula, abscess, urinary tract infection, antibiotic therapy, surgical operation, and health-related quality of life were modeled as separate compartments, with time-dependent relationships among them. The simulation was carried out on an Excel spreadsheet.

RESULTS

In the model, the surgeon's predictions were associated with rapid resolution of the pelvic abscess under antibiotic therapy and improvement of the patient's health status. The gastroenterologist's predictions resulted in a smaller decline in abscess size and further deterioration of the patient's health while waiting for a definitive treatment. The disagreement between surgery and gastroenterology arose from predicting different time courses for the individual disease events, in essence, from assigning different time constants to the time-dependent influences of the disease model.

CONCLUSIONS

The compartment model provides a simple and generally applicable method to assess time dependent-changes of a complex disease. The present analysis also serves to illustrate the usefulness of such models in simulating disease behavior.

The LIM-only protein DRAL/FHL2 binds to the cytoplasmic domain of several alpha and beta integrin chains and is recruited to adhesion complexes

LIM proteins contain one or more double zinc finger structures (LIM domains) mediating specific contacts between proteins that participate in the formation of multiprotein complexes. We report that the LIM-only protein DRAL/FHL2, with four and a half LIM domains, can associate with alpha(3A), alpha(3B), alpha(7A), and several beta integrin subunits as shown in yeast two-hybrid assays as well as after overexpression in human cells. The amino acid sequence immediately following the conserved membrane-proximal region in the integrin alpha subunits or the C-terminal region with the conserved NXXY motif of the integrin beta subunits are critical for binding DRAL/FHL2. Furthermore, the DRAL/FHL2 associates with itself and with other molecules that bind to the cytoplasmic domain of integrin alpha subunits. Deletion analysis of DRAL/FHL2 revealed that particular LIM domains or LIM domain combinations bind the different proteins. These results, together with the fact that full-length DRAL/FHL2 is found in cell adhesion complexes, suggest that it is an adaptor/docking protein involved in integrin signaling pathways.

Cost-effectiveness of colonoscopy in screening for colorectal cancer

BACKGROUND

Fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy are used to screen patients for colorectal cancer.

OBJECTIVE

To compare the cost-effectiveness of fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy.

DESIGN

The cost-effectiveness of the three screening strategies was compared by using computer models of a Markov process. In the model, a hypothetical population of 100 000 persons 50 years of age undergoes annual fecal occult blood testing, sigmoidoscopy every 5 years, or colonoscopy every 10 years. Positive results on fecal occult blood testing or adenomatous polyps found during sigmoidoscopy are worked up by using colonoscopy. After polypectomy, colonoscopy is repeated every 3 years until no polyps are found.

DATA SOURCES

Transition rates were estimated from U.S. vital statistics and cancer statistics and from published data on the sensitivity, specificity, and efficacy of various screening techniques. Costs of screening and cancer care were estimated from Medicare reimbursement data.

TARGET POPULATION

Persons 50 years of age in the general population.

TIME HORIZON

The study population was followed annually until death.

PERSPECTIVE

Third-party payer.

OUTCOME MEASURE

Incremental cost-effectiveness ratio.

RESULTS OF BASE-CASE ANALYSIS

Compared with colonoscopy, annual screening with fecal occult blood testing costs less but saves fewer life-years. A screening strategy based on flexible sigmoidoscopy every 5 or 10 years is less cost-effective than the other two screening methods.

RESULTS OF SENSITIVITY ANALYSIS

Screening with fecal occult blood testing is more sensitive to changes in compliance rates, and it becomes easily dominated by colonoscopy under most conditions assuming less than perfect compliance. Other assumptions about the sensitivity and specificity of fecal occult blood testing, screening frequency, efficacy of colonoscopy in preventing cancer, and polyp incidence have a lesser influence on the differences in cost-effectiveness between colonoscopy and fecal occult blood testing.

CONCLUSIONS

Colonoscopy represents a cost-effective means of screening for colorectal cancer because it reduces mortality at relatively low incremental costs. Low compliance rates render colonoscopy every 10 years the most cost-effective primary screening strategy for colorectal cancer.

Waiting lines in the endoscopy unit

BACKGROUND

The efficient management of the endoscopy unit involves issues of scheduling. The aim of this study was to assess efficient use of an endoscopy unit and its relationship to patient waiting.

METHODS

Formulas of queueing theory are applied to patient scheduling in endoscopy. The M/M/n queueing model assumes exponential (Markovian) distributions underlying both patient arrival and endoscopy times with n as the number of endoscopists, while the D/M/n model assumes a constant (deterministic) patient arrival rate.

RESULTS

As the use of the facility increases, so does the probability that patients will have to wait. It is impossible for an endoscopy facility to have a 100% rate of use without patients being forced to wait. Any increase in the use rate of an endoscopy unit results in a concomitant increase in waiting times. A facility with multiple endoscopists can reduce waiting probability at a higher rate of facility use. A table is included that physicians and administrators can use as a guide to estimate the use rate and waiting characteristics of different types of endoscopy facilities.

CONCLUSIONS

Endoscopy units must find a balance between patient waiting and underuse of their resources. Endoscopists will occasionally find themselves idle at the benefit of providing patients with tolerable waiting times. It needs to be explained to patients that even under the best of circumstances some waiting cannot be prevented.

Defects in adhesion and migration, but not in proliferation and differentiation, of embryonic stem cells upon replacement of integrin subunit beta1A by beta1D

Beta1D is a skeletal muscle-specific splice variant of the beta1 integrin subunit, while beta1A integrin subunit has a wide tissue distribution. We have previously shown that replacement of beta1A by beta1D by homologous recombination (knockin) in all mouse tissues was embryonic lethal. Through two successive rounds of homologous recombination, we have now produced embryonic stem (ES) cells expressing beta1D instead of beta1A, and analyzed the ability of beta1D to support ES cell differentiation in vitro and in teratomas in vivo. Beta1D knockin (KI) ES cells grew at a similar rate but as more compact colonies than the beta1A-expressing cells. Increased cell cohesiveness, however, did not appear to involve changes in cadherin activity. Although in both beta1A and beta1D-KI ES cells only one beta1 allele is active; the expression of beta1 integrins in the beta1D-KI ES cells was reduced by 50%, compared with that in the beta1A-expressing cells; this correlated with impaired adhesive and migratory capacities. It appeared that during in vitro cardiac differentiation, in spite of a slight delay in the induction of two cardiac-specific transcripts, the alpha- and beta-myosin heavy chains, contracting cardiomyocytes were detected in similar numbers and at the same time in embryoid bodies (EB) derived from beta1D-KI and from beta1A cells. Furthermore, replacement of beta1A by beta1D in ES cells did not affect neurite differentiation in embryoid bodies in the presence of retinoic acid suggesting that beta1D supports neurogenesis. However, the impaired migration of other cells from the EB, including endodermal cells, prevented the normal outgrowth of neurites in beta1D-KI EB. Finally, injection of beta1D-KI ES cells in the flank of syngeneic mice gave rise to fully developed teratomas containing simple and pluristratified epithelia, muscle, cartilage, blood vessels, and tissues from the neural lineage. These results show that the muscle-specific splice variant beta1D, in spite of its specific cytoplasmic domain, supports the differentiation of many cell types. This further suggests that the embryonic lethality in the beta1D-KI embryos was mainly due to the different ability of beta1 A and beta1D to mediate cell adhesion and migration.