Vitamin D Deficiency (VDD) and Benefits of Supplementation in Veterans with IBS-D

Many veterans deployed to Gulf War areas suffer from persistent chronic diarrhea that is disabling and affects their quality of life. The causes for this condition have eluded investigators until recently and recent literature has shed light on the effect of vitamin D on the brain-gut axis. This study focused on determining clinical causes contributing to diarrhea and assessed whether reversing the identified causes, specifically vitamin D deficiency (VDD), could reduce the incidence of diarrhea in Gulf War veterans (GWVs). All patients completed a workup that included serologies (IBD, celiac), routine laboratory tests (CBC, chemistry panels, TSH, T4, CRP), cultures for enteric pathogens (C diff, bacteria, viruses, small intestinal bacterial overgrowth (SIBO)), and upper and lower endoscopies with histology and a trial of cholestyramine to exclude choleretic diarrhea and rifaximin for dysbiosis. A total of 4221 veterans were screened for chronic diarrhea, yielding 105 GWVs, of which 69 GWVs had irritable bowel syndrome with diarrhea (IBS-D). Paired t-tests demonstrated that all GWVs had VDD (t-11.62, df68 and sig(2-tailed) 0.0001) (defined as a vitamin D level less than 30 ng/mL with normal ranges of 30-100 ng/mL) but no positive serologies, inflammatory markers, abnormal endoscopies, cultures, or histology to explain their persistent diarrhea. There was no correlation with age, BMI, or inflammation. Some zip codes had a higher frequency of GWVs with VDD, but the number of deployments had no impact. Treatment with vitamin D supplementation (3000-5000 units), given in the morning, based on weight, reduced the number of bowel movements per day (p < 0.0001) without causing hypercalcemia. We suggest that VDD is important in the etiology of IBS-D in GWVs and that vitamin D supplementation significantly reduces diarrhea.

Baseline Features and Reasons for Nonparticipation in the Colonoscopy Versus Fecal Immunochemical Test in Reducing Mortality From Colorectal Cancer (CONFIRM) Study, a Colorectal Cancer Screening Trial

Importance

The Colonoscopy Versus Fecal Immunochemical Test in Reducing Mortality From Colorectal Cancer (CONFIRM) randomized clinical trial sought to recruit 50 000 adults into a study comparing colorectal cancer (CRC) mortality outcomes after randomization to either an annual fecal immunochemical test (FIT) or colonoscopy.

Objective

To (1) describe study participant characteristics and (2) examine who declined participation because of a preference for colonoscopy or stool testing (ie, fecal occult blood test [FOBT]/FIT) and assess that preference's association with geographic and temporal factors.

Design, Setting, and Participants

This cross-sectional study within CONFIRM, which completed enrollment through 46 Department of Veterans Affairs medical centers between May 22, 2012, and December 1, 2017, with follow-up planned through 2028, comprised veterans aged 50 to 75 years with an average CRC risk and due for screening. Data were analyzed between March 7 and December 5, 2022.

Exposure

Case report forms were used to capture enrolled participant data and reasons for declining participation among otherwise eligible individuals.

Main Outcomes and Measures

Descriptive statistics were used to characterize the cohort overall and by intervention. Among individuals declining participation, logistic regression was used to compare preference for FOBT/FIT or colonoscopy by recruitment region and year.

Results

A total of 50 126 participants were recruited (mean [SD] age, 59.1 [6.9] years; 46 618 [93.0%] male and 3508 [7.0%] female). The cohort was racially and ethnically diverse, with 748 (1.5%) identifying as Asian, 12 021 (24.0%) as Black, 415 (0.8%) as Native American or Alaska Native, 34 629 (69.1%) as White, and 1877 (3.7%) as other race, including multiracial; and 5734 (11.4%) as having Hispanic ethnicity. Of the 11 109 eligible individuals who declined participation (18.0%), 4824 (43.4%) declined due to a stated preference for a specific screening test, with FOBT/FIT being the most preferred method (2820 [58.5%]) vs colonoscopy (1958 [40.6%]; P < .001) or other screening tests (46 [1.0%] P < .001). Preference for FOBT/FIT was strongest in the West (963 of 1472 [65.4%]) and modest elsewhere, ranging from 199 of 371 (53.6%) in the Northeast to 884 of 1543 (57.3%) in the Midwest (P = .001). Adjusting for region, the preference for FOBT/FIT increased by 19% per recruitment year (odds ratio, 1.19; 95% CI, 1.14-1.25).

Conclusions and Relevance

In this cross-sectional analysis of veterans choosing nonenrollment in the CONFIRM study, those who declined participation more often preferred FOBT or FIT over colonoscopy. This preference increased over time and was strongest in the western US and may provide insight into trends in CRC screening preferences.

Barrett's Esophagus: Diagnosis, Management, and Key Updates

Barrett's esophagus (BE) is the precursor lesion for esophageal adenocarcinoma (EAC) development. Unfortunately, BE screening/surveillance has not provided the anticipated EAC reduction benefit. Noninvasive techniques are increasingly available or undergoing testing to screen for BE among those with/without known risk factors, and the use of artificial intelligence platforms to aid endoscopic screening and surveillance will likely become routine, minimizing missed cases or lesions. Management of high-grade dysplasia and intramucosal EAC is clear with endoscopic eradication therapy preferred to surgery. BE with low-grade dysplasia can be managed with removal of visible lesions combined with endoscopic eradication therapy or endoscopic surveillance at present.

Artificial intelligence as a means to improve recognition of gastrointestinal angiodysplasia in video capsule endoscopy

Gastrointestinal angiodysplasia (GIAD) is defined as the pathological process where blood vessels, typically venules and capillaries, become engorged, tortuous and thin walled – which then form arteriovenous connections within the mucosal and submucosal layers of the gastrointestinal tract. GIADs are a significant cause of gastrointestinal bleeding and are the main cause for suspected small bowel bleeding. To make the diagnosis, gastroenterologists rely on the use of video capsule endoscopy (VCE) to “target” GIAD. However, the use of VCE can be cumbersome secondary to reader fatigue, suboptimal preparation, and difficulty in distinguishing images. The human eye is imperfect. The same capsule study read by two different readers are noted to have miss rates like other forms of endoscopy. Artificial intelligence (AI) has been a means to bridge the gap between human imperfection and recognition of GIAD. The use of AI in VCE have shown that detection has improved, however the other burdens and limitations still need to be addressed. The use of AI for the diagnosis of GIAD shows promise and the changes needed to enhance the current practice of VCE are near.

Vedolizumab Is Safe in Elderly Veteran Patients With Inflammatory Bowel Disease

Many medications used to treat inflammatory bowel disease (IBD) can increase the risk of infection and cancer, particularly in elderly patients. This study found that vedolizumab, a targeted therapy, was effective and safe in elderly patients with IBD.

Artificial intelligence in Barrett’s esophagus: A renaissance but not a reformation

Esophageal cancer remains as one of the top ten causes of cancer-related death in the United States. The primary risk factor for esophageal adenocarcinoma is the presence of Barrett’s esophagus (BE). Currently, identification of early dysplasia in BE patients requires an experienced endoscopist performing a diagnostic endoscopy with random 4-quadrant biopsies taken every 1-2 cm using appropriate surveillance intervals. Currently, there is significant difficulty for endoscopists to distinguish different forms of dysplastic BE as well as early adenocarcinoma due to subtleties in mucosal texture and color. This obstacle makes taking multiple random biopsies necessary for appropriate surveillance and diagnosis. Recent advances in artificial intelligence (AI) can assist gastroenterologists in identifying areas of likely dysplasia within identified BE and perform targeted biopsies, thus decreasing procedure time, sedation time, and risk to the patient along with maximizing potential biopsy yield. Though using AI represents an exciting frontier in endoscopic medicine, recent studies are limited by selection bias, generalizability, and lack of robustness for universal use. Before AI can be reliably employed for BE in the future, these issues need to be fully addressed and tested in prospective, randomized trials. Only after that is achieved, will the benefit of AI in those with BE be fully realized.

Outcomes Comparison of the Veterans' Choice Program With the Veterans Affairs Health Care System for Hepatitis C Treatment

BACKGROUND

The US Department of Veterans Affairs (VA) has been stressed by the large number of veterans requiring direct-acting antiviral (DAA) medications for hepatitis C virus (HCV) treatment. The Veterans Choice Program provides VA patients more options to receive treatment. This study compared the experience of veterans who received HCV treatment through the Veterans Choice Program and those that received treatment at the VA Loma Linda Healthcare System (VALLHCS) in fiscal year (FY) 2016.

METHODS

A chart review was performed on all veterans referred by VALLHCS to Choice for HCV treatment during FY 2016, and matched to veterans who received treatment at VALLHCS. Data collected included Fibrosis-4 score (Fib-4), platelet count, days elapsed between time of referral and time of appointment (wait time), rate of sustained virologic response at 12 weeks (SVR12), reason for treatment failure, and cost effectiveness.

RESULTS

One hundred veterans were referred to Choice; 71 were seen at least once by a Choice provider, and 61 completed a treatment course. Mean Fib-4 and platelet count was 1.9 and 228,000 for the Choice population and 3.4 and 158,000 for the VALLHCS population, respectively. There was no difference in SVR12 rate. Mean wait time was 42 days for Choice vs 29 days for VALLHCS (P < .001). Choice health care providers incurred a mean $8,561.40 in additional costs per veteran seen.

CONCLUSIONS

While treatment success rates were similar between Choice and VALLHCS, the degree of liver fibrosis was more advanced in the VALLHCS population. The wait time for care was longer with Choice compared with a direct referral within the VA. While Choice offers a potential solution to providing care for veterans, the current program has unique problems that must be considered.

Randomized Trial of Medical versus Surgical Treatment for Refractory Heartburn

BACKGROUND

Heartburn that persists despite proton-pump inhibitor (PPI) treatment is a frequent clinical problem with multiple potential causes. Treatments for PPI-refractory heartburn are of unproven efficacy and focus on controlling gastroesophageal reflux with reflux-reducing medication (e.g., baclofen) or antireflux surgery or on dampening visceral hypersensitivity with neuromodulators (e.g., desipramine).

METHODS

Patients who were referred to Veterans Affairs (VA) gastroenterology clinics for PPI-refractory heartburn received 20 mg of omeprazole twice daily for 2 weeks, and those with persistent heartburn underwent endoscopy, esophageal biopsy, esophageal manometry, and multichannel intraluminal impedance-pH monitoring. If patients were found to have reflux-related heartburn, we randomly assigned them to receive surgical treatment (laparoscopic Nissen fundoplication), active medical treatment (omeprazole plus baclofen, with desipramine added depending on symptoms), or control medical treatment (omeprazole plus placebo). The primary outcome was treatment success, defined as a decrease of 50% or more in the Gastroesophageal Reflux Disease (GERD)-Health Related Quality of Life score (range, 0 to 50, with higher scores indicating worse symptoms) at 1 year.

RESULTS

A total of 366 patients (mean age, 48.5 years; 280 men) were enrolled. Prerandomization procedures excluded 288 patients: 42 had relief of their heartburn during the 2-week omeprazole trial, 70 did not complete trial procedures, 54 were excluded for other reasons, 23 had non-GERD esophageal disorders, and 99 had functional heartburn (not due to GERD or other histopathologic, motility, or structural abnormality). The remaining 78 patients underwent randomization. The incidence of treatment success with surgery (18 of 27 patients, 67%) was significantly superior to that with active medical treatment (7 of 25 patients, 28%; P = 0.007) or control medical treatment (3 of 26 patients, 12%; P<0.001). The difference in the incidence of treatment success between the active medical group and the control medical group was 16 percentage points (95% confidence interval, -5 to 38; P = 0.17).

CONCLUSIONS

Among patients referred to VA gastroenterology clinics for PPI-refractory heartburn, systematic workup revealed truly PPI-refractory and reflux-related heartburn in a minority of patients. For that highly selected subgroup, surgery was superior to medical treatment. (Funded by the Department of Veterans Affairs Cooperative Studies Program; ClinicalTrials.gov number, NCT01265550.).

Endocuff assisted colonoscopy significantly increases sessile serrated adenoma detection in veterans

BACKGROUND

Colorectal cancer (CRC) is the second most common cause of cancer related deaths in the United States. Colonoscopy is the gold standard for the detection of CRC. There are many colonoscopy quality measures and among these the adenoma detection rate (ADR) has demonstrated a significant impact in reducing mortality from CRC. The primary aim of our study was to compare ADR and distribution of polyp type in patients undergoing Endocuff-assisted colonoscopy (EAC) versus standard colonoscopy (SC) in a VA system.

METHODS

Retrospective data was collected from 496 patients who underwent routine screening, surveillance and diagnostic colonoscopies either via SC from January 6, 2014 through March 12, 2014 or EAC from September 24, 2014 through February 19, 2015. A total of 54 patients were excluded based on a personal history of CRC and prior resection, incomplete colonoscopy due to poor bowel preparation, and removal or loss of Endocuff (EC). Primary outcomes measured and compared were ADR and types of polyps found.

RESULTS

The overall ADR in the EAC group was higher at 59.91% versus 50.66% for SC, accounting for a 9% increase (P=0.0508). EAC was able to detect a total of 59 sessile serrated adenoma/polyps (SSA/Ps) compared to SC only detecting 8 (P≤0.0001). There was a significant increase in the SSA/P detection rate with EAC at 15% versus 3% in the SC group (P≤0.0001).

CONCLUSIONS

EAC significantly increases the detection of SSA/P and has shown a trend in improving ADR in our veteran population.

Trend analysis and survival of primary gallbladder cancer in the United States: a 1973-2009 population-based study

Primary gallbladder cancer is an aggressive and uncommon cancer with poor outcomes. Our study examines epidemiology, trend, and survival of gallbladder cancer in the United States from 1973 to 2009. We utilized the Surveillance Epidemiology and End Results database (SEER). Frequency and rate analyses on demographics, stage, and survival were compared among non-Hispanic whites, Hispanics, African American, and Asian/Pacific Islanders. A total of 18,124 cases were reported in SEER from 1973 to 2009 comprising 1.4% of all reported gastrointestinal cancers. Gallbladder cancer was more common in females than males (71 vs. 29%, respectively). The age-adjusted incidence rate was 1.4 per 100,000, significantly higher in females than males (1.7 vs. 1.0). Trend analysis showed that the incidence rate has been decreasing over the last three decades for males. However, among females, the incidence rate had decreased from 1973 to mid-90s but has remained stable since then. Trend analysis for stage at diagnosis showed that the proportion of late-stage cases has been increasing significantly since 2001 after a decreasing pattern since 1973. Survival has improved considerably over time, and survival is better in females than males and in Asian/Pacific Islanders than other racial groups. The highest survival was in patients who received both surgery and radiation. Trend analysis revealed a recent increase of the incidence of late-stage gallbladder cancer. Highest survival was associated with receiving both surgery and radiation.

The efficacy of intracolonic vancomycin for severe Clostridium difficile colitis: a case series

Background

Clostridium difficile infection (CDI) unresponsive to the standard treatments of metronidazole and oral vancomycin requires aggressive medical management and possible surgical intervention including colectomy. Intracolonic vancomycin therapy has been reported to be particularly promising in the setting of severe CDI in the presence of ileus. This is a descriptive case series exploring the effect of adjunctive intracolonic vancomycin therapy on the morbidity and mortality in patients with moderate to severe CDI.

Methods

A retrospective chart review was conducted on 696 patients with CDI seen at a single institution. Each patient was assigned a severity score and 127 patients with moderate to severe CDI were identified. We describe the clinical presentation, risk factors and hospital course comparing those that received adjunctive intracolonic vancomycin to those that only received standard therapy.

Results

The group that received adjunctive intracolonic vancomycin had higher rates of toxic megacolon, intensive care unit (ICU) admission, and colectomy, and yet maintained a similar mortality rate as the group that received only standard treatment.

Conclusion

The intracolonic vancomycin group experienced more complications but showed a similar mortality rate to the standard therapy group, suggesting that intracolonic vancomycin may impart a protective effect. This study adds further evidence for the need of a randomized controlled study using intracolonic vancomycin as adjunctive therapy in patients presenting with severe CDI.

Health disparities in colorectal cancer among racial and ethnic minorities in the United States

In the 2010 Census, just over one-third of the United States (US) population identified themselves as being something other than being non-Hispanic white alone. This group has increased in size from 86.9 million in 2000 to 111.9 million in 2010, representing an increase of 29 percent over the ten year period. Per the American Cancer Society, racial and ethnic minorities are more likely to develop cancer and die from it when compared to the general population of the United States. This is particularly true for colorectal cancer (CRC). The primary aim of this review is to highlight the disparities in CRC among racial and ethnic minorities in the United States. Despite overall rates of CRC decreasing nationally and within certain racial and ethnic minorities in the US, there continue to be disparities in incidence and mortality when compared to non-Hispanic whites. The disparities in CRC incidence and mortality are related to certain areas of deficiency such as knowledge of family history, access to care obstacles, impact of migration on CRC and paucity of clinical data. These areas of deficiency limit understanding of CRC's impact in these groups and when developing interventions to close the disparity gap. Even with the implementation of the Patient Protection and Affordable Healthcare Act, disparities in CRC screening will continue to exist until specific interventions are implemented in the context of each of racial and ethnic group. Racial and ethnic minorities cannot be viewed as one monolithic group, rather as different segments since there are variations in incidence and mortality based on natural history of CRC development impacted by gender, ethnicity group, nationality, access, as well as migration and socioeconomic status. Progress has been made overall, but there is much work to be done.

Higher prevalence of proximal colon polyps and villous histology in African-Americans undergoing colonoscopy at a single equal access center

BACKGROUND

In the United States, African Americans (AA) have the highest incidence and mortality from colorectal cancer (CRC) of any racial group. Few studies have evaluated if AA who undergo colonoscopy are more likely to have aggressive neoplasia (polyp) tumor biology compared to Caucasians (C). The primary aim of the study was to compare polyp characteristics between AA and C undergoing outpatient colonoscopy.

METHODS

A single center retrospective cohort study was performed at a single Veteran Administration (VA) health care system. The charts of 4,038 veterans undergoing colonoscopy from 2005 to 2008 were reviewed. After applying exclusion criteria, data was analyzed for 1,388 persons. Categorical variables were compared using the chi-square test and data were expressed as percentages. Continuous variables were compared using student's t-test and the data were expressed as mean with standard deviation.

RESULTS

A total of 37% of AA had proximal polyps compared to 21% of C (P<0.0001). Twenty-four percent of AA had polyps with villous histology compared to 16% of C (P=0.01). Twelve percent of AA had hyperplastic polyps compared to 20% of C (P=0.02). There was no difference in the overall prevalence of tubular adenomas, adenomatous polyps with high-grade dysplasia, number, size or polyp morphology between groups.

CONCLUSIONS

In an equal access healthcare system and under varying indications, AA have more proximal polyps and polyps with more aggressive histology compared to C. This could partially explain the higher incidence of CRC in AA, and the increased likelihood for AA to develop advanced proximal neoplasia.

Increased risk for colorectal cancer under age 50 in racial and ethnic minorities living in the United States

Colorectal cancer (CRC) is the second most common cause of cancer death in USA. We analyzed CRC disparities in African Americans, Hispanics, Asians/Pacific Islanders, and American Indians/Alaska Natives compared to non‐Hispanic Whites. Current guidelines recommend screening for CRC beginning at age 50. Using SEER (Surveillance, Epidemiology, and End Results) database 1973–2009 and North American Association of Central Cancer Registries (NAACCR) 1995–2009 dataset, we performed frequency and rate analysis on colorectal cancer demographics and incidence based on race/ethnicity. We also used the SEER database to analyze stage, grade, and survival based on race/ethnicity. Utilizing SEER database, the median age of CRC diagnosis is significantly less in Hispanics (66 years), Asians/Pacific Islanders (68 years), American Indians/Alaska Natives (64 years), and African Americans (64 years) compared to non‐Hispanic whites (72 years). Twelve percent of Asians/Pacific Islanders, 15.4% Hispanics, 16.5% American Indians/Alaska Natives, and 11.9% African Americans with CRC are diagnosed at age <50 years compared to only 6.7% in non‐Hispanic Whites (P < 0.0001). Minority groups have more advanced stages at diagnosis compared to non‐Hispanic Whites. Trend analysis showed age‐adjusted incidence rates of CRC diagnosed under the age of 50 years have significantly increased in all racial and ethnic groups but are stable in African Americans. These results were confirmed through analysis of NAACCR 1995–2009 dataset covering nearly the entire USA. A significantly higher proportion of minority groups in USA with CRC are diagnosed before age 50 compared to non‐Hispanic Whites, documenting that these minority groups are at higher risk for early CRC. Further studies are needed to identify the causes and risk factors responsible for young onset CRC among minority groups and to develop intervention strategies including earlier CRC screening, among others.

Bleeding Meckel's diverticulum diagnosed and treated by double-balloon enteroscopy

Meckel's diverticulum (MD) is the most common congenital anomaly of the gastrointestinal (GI) tract. The diagnosis of symptomatic MD has been cumbersome. Several case reports been published regarding direct visualization of MD with double balloon enteroscopy (DBE); diagnosing a bleeding MD leading to surgical resection. We report the use of DBE for the treatment of a bleeding MD.

A pilot study to assess feasibility of the water method to aid colonoscope insertion in community settings in the United States

BACKGROUND: The water method decreases patient discomfort and sedation requirement. Applicability in non-veteran community settings in the United States (U.S.) has not been reported. AIMS: Our aim is to perform a pilot study to establish feasibility of use the water method at 2 community sites. We tested the hypothesis that compared with air insufflation patients examined with the water method would require less sedation without adverse impact on outcomes. METHODS: Two performance improvement projects were carried out. Consecutive patients who consented to respond to a questionnaire after colonoscopy were enrolled. Project 1: The design was single-blinded (patient only); quasi-randomized - odd days (water), even days (air). Colonoscopy was performed by a staff attending. Project 2: A supervised trainee performed the reported procedures. In both, patient demographics (age, gender and body mass index), amount of sedation required during colonoscopy and procedure-related variables were recorded. The patients completed a questionnaire that enquired about discomfort during colonoscopy and willingness to repeat the procedure within 24 hours after the procedure. RESULTS: Project 1: Significantly lower doses of fentanyl and midazolam were used and a higher adenoma detection rate (ADR) was demonstrated in the water group. Project 2: 100% cecal intubation rate was achieved by the supervised trainee. CONCLUSION: This is the first pilot report in the U.S. documenting feasibility of the water method as the principal modality to aid colonoscope insertion in both male and female community patients. In a head-to-head comparison, significant reduction of sedation requirement is confirmed as hypothesized. No adverse impact on outcomes was noted.

Push enteroscopy has a 96% cecal intubation rate in colonoscopies that failed because of redundant colons

BACKGROUND

Performing a complete colonoscopy to the cecum is important for ruling out malignancy and other lesions, but failure rates are significant with a standard colonoscope. A previous study using a push enteroscope for failed colonoscopies had a completion rate of 68.7%.

OBJECTIVE

To improve the cecal intubation rate by using a newer version of a push enteroscope.

DESIGN

Retrospective study at first, then a prospective study.

SETTING

Single-center veterans health care system.

PATIENTS

A total of 47 patients in whom the cecum was not reached with a regular adult colonoscope between January 2007 and December 2010 were included. Those with poor bowel preparation were excluded.

INTERVENTIONS

Repeat colonoscopy using a new version of a push enteroscope.

MAIN OUTCOME MEASUREMENTS

The rate of cecal intubation and additional pathological findings.

RESULTS

The cecum or terminal ileum was reached in 45 patients (96%). Additional significant pathological findings in the previously unexamined colon were seen in 18 patients (38%).

LIMITATIONS

Small sample size, lack of comparison with other endoscopes.

CONCLUSIONS

Colonoscopy with a push enteroscope could be advanced to either the terminal ileum or cecum in 96% of patients, which is one of the highest known completion rates in patients in whom colonoscopy failed. Clinical management changed in all patients with additional findings.

Mesenteric vascular thromboembolism in inflammatory bowel disease: a single center experience

BACKGROUND

Vascular thrombotic complications in inflammatory bowel disease (IBD) are well recognized, although mesenteric vascular thrombotic disease is rare.

METHODS

We describe nine patients in a tertiary care center with IBD that developed thrombosis of the mesenteric arterial or venous vasculature (e.g., mesenteric thrombosis, MT).

RESULTS

Eight subjects developed mesenteric venous thrombosis (five located in the superior mesenteric vein and three located in a branch of the portal vein) and one had a mesenteric arterial embolus, located in the splenic artery. Five subjects had Crohn's disease (CD), and four had ulcerative colitis. The one subject diagnosed with an arterial thrombosis had CD. Mean time from diagnosis of IBD to diagnosis of thrombosis was 24.6 ± 13.5 years. Five of the nine subjects developed mesenteric venous thrombosis while their IBD was clinically in remission. Seven of nine subjects were symptomatic from the development of MT, including bowel infarction that led to development of short bowel syndrome.

CONCLUSION

Mesenteric thrombosis is a rare complication of IBD and may develop during clinical remission, suggesting a potential role for factors other than clinically significant inflammation in its pathogenesis.

Prevention of colorectal cancer with vitamin D

The fact that colorectal cancer (CRC) is the second leading cause of cancer mortality in the United States emphasizes the need for more effective preventive and therapeutic modalities. There is growing evidence that vitamin D may reduce the incidence of CRC. Results of epidemiologic, in vitro, in vivo animal and clinical studies suggest that a low serum vitamin D level may be a serious risk factor for CRC and a high serum vitamin D level may reduce the risk of CRC. On a molecular level, vitamin D suppresses CRC development and growth by affecting cell proliferation, differentiation, apoptosis, and angiogenesis. Vitamin D insufficiency and CRC are common in the elderly population. Vitamin D insufficiency is simple to screen for and treatable with vitamin D supplementation. Serum 25-hydroxyvitamin D (calcidiol) is the best measure of vitamin D status and should be checked routinely for individuals with risk factors for CRC. Maintaining serum concentrations of calcidiol above 32 ng/ml (80 nmol/l) in individuals whose serum calcidiol level is low may help prevent CRC as well as osteoporosis, fractures, infections, and cardiovascular disease. Daily calcidiol intake of 1000 International Units can increase serum vitamin D to sufficient levels in most elderly persons and, based on available data, may substantially lower the incidence of CRC with minimal risks.

Metabolic labeling with fatty acids

Covalent attachment of radiolabeled fatty acids (e.g., [(3)H]myristate or palmitate) is an alternative method for labeling proteins. This unit contains methods for biosynthetic labeling with fatty acids, analysis of the fatty acid linkage with protein, analysis of total protein-bound fatty acid level in cell extracts, and analysis of the identity of the bound fatty acid.

The nutritional management of short bowel syndrome

Short bowel syndrome (SBS) is the predominant cause of intestinal failure and is associated with a high degree of morbidity and mortality. One of the reasons this occurs is because of the dramatic reduction in nutrient absorptive capacity. There are many causes for the development of SBS, but the most common is extensive surgical resection. The bowel has an impressive ability to adapt both morphologically and functionally. This adaptation becomes critical in decreasing morbidity and mortality. It is also critical for the improvement of quality of life and long-term outcomes. Provision of sufficient nutritional and fluid support is essential to the management of SBS patients. The primary goal is to prevent or eliminate the need for total parenteral nutrition. Specific diets and hormonal therapy may enhance the adaptation process depending on the characteristics of the remaining bowel. For those patients who experience both intestinal failure and life-threatening complications from total parenteral nutrition, bowel transplantation may be indicated.

Analysis of protein acylation

Protein acylation is the covalent attachment of fatty acids to a protein; the most commonly added fatty acids are myristate (14:0) and palmitate (16:0). In this unit, protocols describe the use of radiolabeled fatty acids to label eukaryotic cells in vitro. The radiolabeled material produced can then be analyzed by the various methods described here: determination of the type of fatty acid linkage, checking for interconversion by determining the nature of the protein-bound label, and identification of the protein-bound fatty acid.

Pseudo-enzymatic S-acylation of a myristoylated yes protein tyrosine kinase peptide in vitro may reflect non-enzymatic S-acylation in vivo

Covalent attachment of a variety of lipid groups to proteins is now recognized as a major group of post-translational modifications. S-acylation of proteins at cysteine residues is the only modification considered dynamic and thus has the potential for regulating protein function and/or localization. The activities that catalyse reversible S-acylation have not been well characterized and it is not clear whether both the acylation and the deacylation steps are regulated, since in principle it would be sufficient to control only one of them. Both apparently enzymatic and non-enzymatic S-acylation of proteins have previously been reported. Here we show that a synthetic myristoylated c-Yes protein tyrosine kinase undecapeptide undergoes spontaneous S-acylation in vitro when using a long chain acyl-CoA as acyl donor in the absence of any protein. The S-acylation was dependent on myristoylation of the substrate, the length of the incubation period, temperature and substrate concentration. When COS cell fractions were added to the S-acylation reaction no additional peptide:S-acyltransferase activity was detected. These results are consistent with the possibility that membrane-associated proteins may undergo S-acylation in vivo by non-enzymatic transfer of acyl groups from acyl-CoA. In this case, the S-acylation-deacylation process could be controlled by a regulated depalmitoylation mechanism.

Catalytic antibody activity elicited by active immunisation. Evidence for natural variation involving preferential stabilization of the transition state

1. The hydrolytic activity of IgG purified from (a) 13 samples of ovine antiserum collected from three animals during a two-year immunisation programme using a phosphate immunogen (comprising the amide conjugate bonded through the carboxy group of 4-nitrophenyl 4-carboxymethylphenyl hydrogen phosphate and amino groups of keyhole-limpet haemocyanin) and (b) a sample of ovine antiserum collected from another animal during an 18-week immunisation programme using an analogous sulphone immunogen (comprising the amide conjugate bonded through the amino group of 4-nitrobenzyl, 4-(4-aminobutoxy)benzyl sulphone and carboxyl groups of keyhole-limpet haemocyanin) were evaluated kinetically by using 4-nitrophenyl 4-(3-aza-2-oxoheptyl)phenyl carbonate and 4-nitrophenyl 4-(2-hydroxyethoxy)phenyl carbonate as substrates. 2. Catalytic activity was found in all 13 samples of anti-phosphate IgG but was absent in the sample of anti-sulphone IgG as well as in all samples of IgG isolated from the serum of non-immunised animals. These findings, taken together with the lack of catalytic activity of the anti-phosphate IgG towards the 2-nitrophenyl 4-(3-aza-2-oxoheptyl)phenyl carbonate, compel the view that the catalytic activity of the anti-phosphate IgG preparation is entirely antibody-mediated and is not due to contaminant hydrolytic enzymes. The fact that catalytic activity was found in all 13 samples of the anti-phosphate IgG provides the first evidence that it is possible, as a routine, to elicit a catalytic antibody response in a host animal via active immunisation. 3. The nature of the, albeit small, variation in the catalytic characteristics of the anti-phosphate IgG (increase in both kcat, the catalytic rate constant calculated as V/2[IgG] and kcat/Km, the apparent second-order rate constant for the overall catalysed conversion of substrate to products, with increase in Km suggests simultaneous improvement in transition state binding and deterioration in substrate binding as predicted from immunogen design and the postulated general mechanistic basis of antibody catalysis. 4. This interpretation is supported by the difference in the values of the dissociation constant Ki for the competitive inhibition by the transition-state analogue 4-methylphenyl 4-nitrophenyl hydrogen phosphate of reactions catalysed by two representative anti-phosphate IgG samples: for the catalysis with Km = 4.5 microM, Ki = 9 nM and for that with Km = 1.3 microM, Ki = 80 nM.(ABSTRACT TRUNCATED AT 400 WORDS)

Polyclonal antibody-catalysed amide hydrolysis

1. The activated amide (4-nitroanilide), N-(4-nitrophenyl) N'-butyl-1,4-phenylenediacetamide (III) was synthesized. 2. A polyclonal antibody preparation (PCA 270-29) was elicited in a multigeneration cross-bred sheep (no. 270) and isolated 29 weeks into the immunization schedule by procedures described previously for PCA 270-22 [Gallacher, Jackson, Searcey, Badman, Goel, Topham, Mellor & Brocklehurst (1991) Biochem J. 271, 871-881]. These involved the use of an amide conjugate bonded through the carboxy group of 4-nitrophenyl 4'-carboxymethylphenyl phosphate and an amino group of keyhole-limpet haemocyanin as the immunogen. 3. PCA 270-29 was shown to catalyse the hydrolysis of both the carbonate ester substrate 4-nitrophenyl 4'-(3-aza-2-oxoheptyl)phenyl carbonate (I) and the amide substrate (III). Both catalyses obeyed the Michaelis-Menten equation with the following values of the parameters at 25 degrees C: for the hydrolysis of (I) at pH 8.0, Km = 3.96 +/- 0.28 microM and k(cat.) = 0.135 +/- 0.004 s-1 (k(non-cat.) = 1.99 x 10(-4) s-1); for the hydrolysis of (III) at pH 9.0, Km = 5.4 +/- 1.4 microM and k(cat.) = (5.95 +/- 0.75) x 10(-5) s-1 (k(non-cat.) = approx. 2 x 10(-7) s-1). 4. The finding that PCA 270-29 is almost equally effective as a catalyst for the hydrolysis of the amide (III) as for that of the carbonate ester (I) when allowance is made for the different intrinsic reactivities of the two types of substrate is discussed. The catalytic characteristics of PCA 270-29, the first example of a polyclonal catalytic antibody preparation shown to catalyse the hydrolysis of an amide and the first example of an antibody preparation (monoclonal or polyclonal) with such catalytic character to be produced by use of a phosphate immunogen, are compared with those of the small number of other antibody-mediated hydrolyses of amides in the literature.

A polyclonal antibody preparation with Michaelian catalytic properties

1. 4-Nitrophenyl 4'-(3-aza-2-oxoheptyl)phenyl carbonate (I), an amide conjugate (XI) involving the carboxy group of 4-nitrophenyl 4'-carboxymethylphenyl phosphate and an amino group of keyhole-limpet haemocyanin, and a fluorescein derivative (XVII) were synthesized. 2. The conjugate (XI) was used as an immunogen with which to raise polyclonal antibodies in multigeneration cross-bred sheep; the fluorescent derivative (XVII) was used for the initial assessment of the antisera via binding assays monitored by fluorescence polarization; the carbonate ester (I) was used as a chromogenic substrate for the investigation of catalytic activity. 3. The IgG from the antiserum of sheep no. 270 was isolated by Na2SO4 precipitation and chromatography on Protein G-Sepharose. 4. This preparation of IgG catalysed the hydrolysis of the carbonate ester (I); the catalysis at pH 8.0 and 25 degrees C obeyed Michaelis-Menten kinetics with at least 25 turnovers, Km = 3.34 microM, and lower limits for kcat. of 0.029 s-1 and for kcat./Km of 8.77 x 10(3) M-1.S-1, on the unlikely assumption that the concentration of catalytic antibody is provided by twice the total IgG concentration (two sites per molecule); probable estimates of the fraction of the total IgG that is anti-haptenic IgG and of the fraction of this that is catalytically active suggest that the values of kcat./Km are actually very much larger than these lower limits. 5. The failure of the antibody preparation to catalyse the hydrolysis of the isomeric 2-nitrophenyl carbonate (II), which differs from compound (I) only in the position of the nitro substituent in the leaving group, compels the view that catalytic activity is due to antibody rather than contaminant enzyme; this conclusion is supported by (a) the failure of the following to discriminate effectively between the isomeric substrates (I) and (II): pig liver carboxylesterase, rabbit liver carboxylesterase (collectively EC 3.1.1.1), whole serum from a non-immunized sheep and whole serum from a sheep immunized with a derivative of 3-O-methylnoradrenaline and (b) the lack of catalytic activity in IgG preparations from sheep immunized with sulphoxide or sulphone analogues of immunogen (XI). 6. The various parameters used for the comparison of the kinetic characteristics of hydrolytic catalytic antibodies are discussed. 7. The characteristics of hydrolysis of compound (I) catalysed by the present polyclonal antibody preparation are shown to be substantially better in most respects than those of analogous reactions of two other carbonate esters catalysed by monoclonal antibodies.