Biliary lipid composition in patients with nonoperated Crohn's disease

Association of serum lipids with inflammatory bowel disease: a systematic review and meta-analysis

Background

Serum lipid levels seem to be abnormal in Inflammatory bowel disease (IBD). However, the specific manifestation of abnormal serum lipid levels in IBD are heterogeneous among studies and have not been sufficiently determined yet.

Methods

PubMed, EMBASE, and Cochrane Library databases were searched. Serum lipid levels were compared between IBD patients and Health individuals, Crohn's (CD) and ulcerative colitis (UC), active and inactive, mild and non-mild patients, respectively. Meta-analyses were performed by using a random-effect model. Weight mean difference (WMD) with 95% confidence intervals (CIs) were calculated.

Results

Overall, 53 studies were included. Compared with healthy controls, IBD patients had significantly lower TC (WMD = -0.506, 95%CI = -0.674 to -0.338, p < 0.001), HDL-c (WMD = -0.122, 95%CI = -0.205 to -0.039, p = 0.004), and LDL-c (WMD = -0.371, 95%CI = -0.547 to -0.194, p < 0.001) levels. CD groups had a significantly lower TC (WMD = -0.349, 95%CI = -0.528 to -0.170, p < 0.0001) level as compared to UC groups. Active IBD and non-mild UC groups had significantly lower TC (WMD = -0.454, 95%CI = -0.722 to -0.187, p = 0.001) (WMD =0.462, 95%CI = 0.176 to 0.748, p = 0.002) and LDL-c (WMD = -0.225, 95%CI = -0.445 to -0.005, p = 0.045) (WMD =0.346, 95%CI = 0.084-0.609, p = 0.010) levels as compared to inactive IBD and mild UC groups, respectively.

Conclusion

The overall level of serum lipids in IBD patients is lower than that of healthy individuals and is negatively associated with disease severity.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022383885.

Bile acids as inflammatory mediators and modulators of intestinal permeability

Bile acids are critical for the digestion and absorption of lipids and fat-soluble vitamins; however, evidence continues to emerge supporting additional roles for bile acids as signaling molecules. After they are synthesized from cholesterol in the liver, primary bile acids are modified into secondary bile acids by gut flora contributing to a diverse pool and making the composition of bile acids highly sensitive to alterations in gut microbiota. Disturbances in bile acid homeostasis have been observed in patients with Inflammatory Bowel Diseases (IBD). In fact, a decrease in secondary bile acids was shown to occur because of IBD-associated dysbiosis. Further, the increase in luminal bile acids due to malabsorption in Crohn's ileitis and ileal resection has been implicated in the induction of diarrhea and the exacerbation of inflammation. A causal link between bile acid signaling and intestinal inflammation has been recently suggested. With respect to potential mechanisms related to bile acids and IBD, several studies have provided strong evidence for direct effects of bile acids on intestinal permeability in porcine and rodent models as well as in humans. Interestingly, different bile acids were shown to exert distinct effects on the inflammatory response and intestinal permeability that require careful consideration. Such findings revealed a potential effect for changes in the relative abundance of different bile acids on the induction of inflammation by bile acids and the development of IBD. This review summarizes current knowledge about the roles for bile acids as inflammatory mediators and modulators of intestinal permeability mainly in the context of inflammatory bowel diseases.

Pancreatic Disorders in Patients with Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) can involve multiple organ systems, and pancreatic manifestations of IBD are not uncommon. The incidence of several pancreatic diseases is more frequent in patients with Crohn's disease and ulcerative colitis than in the general population. Pancreatic manifestations in IBD include a heterogeneous group of disorders and abnormalities ranging from mild, self-limited disorders to severe diseases. Asymptomatic elevation of amylase and/or lipase is common. The risk of acute pancreatitis in patients with IBD is increased due to the higher incidence of cholelithiasis and drug-induced pancreatitis in this population. Patients with IBD commonly have altered pancreatic histology and chronic pancreatic exocrine dysfunction. Diagnosing acute pancreatitis in patients with IBD is challenging. In this review, we discuss the manifestations and possible causes of pancreatic abnormalities in patients with IBD.

Alterations in Bile Acid Metabolism Associated With Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder closely related to gut dysbiosis, which is associated with alterations in an important bacterial metabolite, bile acids (BAs). Although certain findings pertinent to BA changes in IBD vary among studies owing to the differences in sample type, quantitated BA species, study methodology, and patient characteristics, a specific trend concerning variations of BAs in IBD has been identified. In elaborating on this observation, it was noted that primary BAs and conjugated BAs are augmented in fecal samples but there is a reduction in secondary BAs in fecal samples. It is not entirely clear why patients with IBD manifest these changes and what role these changes play in the onset and development of IBD. Previous studies have shown that IBD-associated BA changes may be caused by alterations in BA absorption, synthesis, and bacterial modification. The complex relationship between bacteria and BAs may provide additional and deeper insight into host-gut microbiota interactions in the pathogenesis of IBD. The characteristic BA changes may generate profound effects in patients with IBD by shaping the gut microbiota community, affecting inflammatory processes, causing BA malabsorption associated with diarrhea, and even leading to intestinal dysplasia and cancer. Thus, therapeutic strategies correcting the alterations in the composition of BAs, including the elimination of excess BAs and the supplementation of deficient BAs, may prove promising in IBD.

The Vat-AIEC protease promotes crossing of the intestinal mucus layer by Crohn's disease-associated Escherichia coli

The aetiology of Crohn's disease (CD) involves disorders in host genetic factors and intestinal microbiota. Adherent-invasive Escherichia coli (AIEC) are receiving increased attention because in studies of mucosa-associated microbiota, they are more prevalent in CD patients than in healthy subjects. AIEC are associated both with ileal and colonic disease phenotypes. In this study, we reported a protease called Vat-AIEC from AIEC that favours the mucosa colonization. The deletion of the Vat-AIEC-encoding gene resulted in an adhesion-impaired phenotype in vitro and affected the colonization of bacteria in contact with intestinal epithelial cells in a murine intestinal loop model, and also their gut colonization in vivo. Furthermore, unlike LF82Δvat-AIEC, wild-type AIEC reference strain LF82 was able to penetrate a mucus column extensively and promoted the degradation of mucins and a decrease in mucus viscosity. Vat-AIEC transcription was stimulated by several chemical conditions found in the ileum environment. Finally, the screening of E. coli strains isolated from CD patients revealed a preferential vat-AIEC association with AIEC strains belonging to the B2 phylogroup. Overall, this study revealed a new component of AIEC virulence that might favour their implantation in the gut of CD patients.

Escherichia coli in chronic inflammatory bowel diseases: An update on adherent invasive Escherichia coli pathogenicity

Escherichia coli (E. coli), and particularly the adherent invasive E. coli (AIEC) pathotype, has been increasingly implicated in the ethiopathogenesis of Crohn’s disease (CD). E. coli strains with similar pathogenic features to AIEC have been associated with other intestinal disorders such as ulcerative colitis, colorectal cancer, and coeliac disease, but AIEC prevalence in these diseases remains largely unexplored. Since AIEC was described one decade ago, substantial progress has been made in deciphering its mechanisms of pathogenicity. However, the molecular bases that characterize the phenotypic properties of this pathotype are still not well resolved. A review of studies focused on E. coli populations in inflammatory bowel disease (IBD) is presented here and we discuss about the putative role of this species on each IBD subtype. Given the relevance of AIEC in CD pathogenesis, we present the latest research findings concerning AIEC host-microbe interactions and pathogenicity. We also review the existing data regarding the prevalence and abundance of AIEC in CD and its association with other intestinal diseases from humans and animals, in order to discuss the AIEC disease- and host-specificity. Finally, we highlight the fact that dietary components frequently found in industrialized countries may enhance AIEC colonization in the gut, which merits further investigation and the implementation of preventative measures.

Systematic review: The epidemiology of the hepatobiliary manifestations in patients with inflammatory bowel disease

BACKGROUND

Extraintestinal manifestations are frequent in inflammatory bowel diseases (IBD). Most studies published so far focused on viral hepatitis and liver toxicity of IBD-related drugs.

AIM

To conduct a systematic review of hepatobiliary manifestations associated with IBD. We excluded viral hepatitis and liver toxicity of IBD-related drugs.

METHODS

Studies were identified through the electronic database of MEDLINE, EMBASE and the annual meetings of Digestive Disease Week, the American College of Gastroenterology, the United European Gastroenterology Week and the European Crohn's and Colitis Organization.

RESULTS

One hundred and forty six articles were included in this systematic review. Cholelithiasis is more frequent in Crohn's disease (CD) than in general population. Prevalence of cholelithiasis in CD ranged from 11% to 34%, whereas it ranges from 5.5% to 15% in non-IBD patients. PSC is more frequent in UC than in CD. Prevalence of PSC ranges from 0.76% to 5.4% in UC and from 1.2% to 3.4% in CD. There is a male predominance when PSC is associated with UC, with a male/female ratio ranging from 65/35 to 70/30. No conclusion can be made on a possible increased risk of gall-bladder carcinoma. Mean prevalence of fatty liver is 23% (range, 1.5-55%). Hepatic amyloidosis occurs in less than 1% of IBD. Liver abscess is encountered mainly in CD. Portal vein thrombosis occurs in 39% to 45% of IBD patients undergoing proctocolectomy.

CONCLUSIONS

Hepatobiliary manifestations associated with inflammatory bowel diseases are frequent and probably underdiagnosed.

Gallstones increase the risk of developing renal stones: a nationwide population-based retrospective cohort study

BACKGROUND

This study identifies the effects of gall stone on the risks of developing renal stone in a nationwide cohort study.

AIM

Studies on the association between gall stone and renal stone are scarce.

METHODS

We identified patients with gallstones using the catastrophic illness registry of the Taiwan National Health Insurance Research Database (NHIRD). We selected a comparison cohort, random frequency-matched by age, sex and index year, from the general population. We analyzed the risk of renal stones by using Cox proportional hazards regression models for sex, age and comorbidities.

RESULTS

Of the 23.74 million people in the database, we followed 25 258 gallstone patients (54.5% female) and 101 029 control patients. The risk of developing renal stones was 1.68-fold greater in gallstone patients, compared with patients without gallstones after adjusting for age, sex and comorbidities. The substantially increased risk of renal stones was also significant in gallstone patients regardless of comorbidities. In the follow-up period <1 year, the adjusted hazard ratio was 2.51 (95% CI = 2.25-2.80) compared to non-gallstone group. The cumulative incidence of renal stone in the gallstone group was higher than in the non-gallstone group (P < 0.0001, in the log-rank test).

CONCLUSION

This nationwide cohort study demonstrates that the risk of renal stones is significantly higher in gallstone patients, compared with the general population. This study provides information to enable physicians to implement adequate prevention measures to decrease both stones formation.

Bile salts induce long polar fimbriae expression favouring Crohn's disease-associated adherent-invasive Escherichia coli interaction with Peyer's patches

Ileal lesions of patients with Crohn's disease are colonized by adherent-invasive Escherichia coli (AIEC). The earliest lesions of recurrent Crohn's disease are erosions of Peyer's patches (PP). We recently reported the presence of a functional lpf operon in AIEC, encoding long polar fimbriae (LPF), that allows AIEC bacteria to interact with PP and to translocate across M cells. The aim of this study was to analyse the effect of gastrointestinal conditions on LPF expression in AIEC strains. The LF82 bacterial growth in an acid pH medium or at high osmolarity medium had no effect on lpf transcription level, in contrast to bacterial growth in the presence of bile salts, which promoted activation of lpf transcription. When cultured in the presence of bile salt, LF82 wild-type bacteria, but not the isogenic mutant deleted for lpfA, exhibited a higher level of interaction with PP and a higher level of translocation through M cell monolayers. The FhlA transcriptional factor was found to be a key bacterial regulator at the origin of LPF expression in the presence of bile salts.

Pancreatitis in inflammatory bowel diseases

Crohn's disease and ulcerative colitis, together popularly known as inflammatory bowel disease (IBD), are characterized by a number of extraintestinal manifestations. Although infrequent, acute pancreatitis, and less often chronic pancreatitis, may occur as a result of the disease itself or secondary to the medications used in the treatment. The increased incidence of acute pancreatitis in Crohn's disease can be explained based on the high predisposition to cholesterol as well as pigment stones as a result of ileal disease, anatomic abnormalities of the duodenum, immunologic disturbances associated with IBD, and, above all, to the side effects of many medications used in the treatment. Sulfasalazine, 5-aminosalicylic acid, azathioprine, and 6-mercaptopurine are well known to cause acute pancreatitis as a result of a possible idiosyncratic mechanism. Crohn's disease and ulcerative colitis share many clinical manifestations and treatment modalities. Nonspecific elevations of serum pancreatic enzymes in IBD make it difficult to avoid over diagnosis of acute pancreatitis, particularly in patients with Crohn's disease who suffer from abdominal pain often. The IBD-pancreas association is further reflected in many reports of exocrine as well as endocrine pancreatic insufficiency.

Atherogenic diet causes lethal ileo-ceco-colitis in cyclooxygenase-2 deficient mice

Cyclooxygenases (COX) regulate a variety of inflammatory diseases, including inflammatory bowel disease (IBD). While the pathological effects of COX-1 inhibition by NSAIDs on intestinal ulceration are well established, the role of COX-2 on intestinal inflammation remains under investigation. In this paper, we report a protective role for COX-2 against diet-mediated intestinal inflammation in mice. COX-2(-/-) mice fed an atherogenic diet or diet containing cholate, but not chow or fat alone, had a high mortality whereas COX-1(-/-) mice and wild-type mice were unaffected by the dietary changes. Histological analysis identified the cause of death in COX-2(-/-) mice due to severe intestinal inflammation that was surprisingly limited to the ileo-ceco-colic junction. COX-2 expression is induced in the cecum of wild-type mice fed an atherogenic diet. Our findings show that COX-2 plays an anti-inflammatory role at the ileo-ceco-colic junction in mice, and the pathology of diet-mediated intestinal inflammation in COX-2(-/-) mice offers an excellent model system to elucidate the molecular mechanisms of intestinal inflammation.

Gallstone disease: Epidemiology of gallbladder stone disease

Gallstone disease is common: >700,000 cholecystectomies and costs of approximately 6.5 billion dollars annually in the U.S. The burden of disease is epidemic in American Indians (60-70%); a corresponding decrease occurs in Hispanics of mixed Indian origin. Ten to fifteen per cent of white adults in developed countries harbour gallstones. Frequency is further reduced in Black Americans, East Asia and sub-Saharan Africa. In developed countries, cholesterol gallstones predominate; 15% are black pigment. East Asians develop brown pigment stones in bile ducts, associated with biliary infection or parasites, or in intrahepatic ducts (hepatolithiasis). Certain risk factors for gallstones are immutable: female gender, increasing age and ethnicity/family (genetic traits). Others are modifiable: obesity, the metabolic syndrome, rapid weight loss, certain diseases (cirrhosis, Crohn's disease) and gallbladder stasis (from spinal cord injury or drugs like somatostatin). The only established dietary risk is a high caloric intake. Protective factors include diets containing fibre, vegetable protein, nuts, calcium, vitamin C, coffee and alcohol, plus physical activity.

Epidemiology and risk factors for gallstone disease: has the paradigm changed in the 21st century?

Gallstone disease is common and costly, creating over 700,000 cholecystectomies annually. Its complications consume approximately $6.5 billion in the United States. Surveys using noninvasive ultrasonography have identified its true prevalence and the associated risk factors. In developed countries, at least 10% of white adults harbor cholesterol gallstones; women have twice the risk, and age further increases the prevalence in both sexes. Gallstones reach epidemic proportions in the North and South American Indian populations, accompanied by an increased risk for gallbladder cancer. In contrast, the rate in sub-Saharan Africa and Asia is quite low. Obesity, a major risk factor, likely relates to insulin resistance (the metabolic syndrome). Evolution and circumstance in American Indians may have ironically selected those with "thrifty" genes that conserve energy. Our abundant access to food places us at the increased risk of obesity and cholelithiasis. The general rise in obesity in many countries raises the specter of heightened disease, best identified by epidemiologic studies.

Epidemiology and risk factors for gallstone disease: has the paradigm changed in the 21st century?

Gallstone disease is common and costly, creating over 700,000 cholecystectomies annually. Its complications consume approximately $6.5 billion in the United States. Surveys using noninvasive ultrasonography have identified its true prevalence and the associated risk factors. In developed countries, at least 10% of white adults harbor cholesterol gallstones; women have twice the risk, and age further increases the prevalence in both sexes. Gallstones reach epidemic proportions in the North and South American Indian populations, accompanied by an increased risk for gallbladder cancer. In contrast, the rate in sub-Saharan Africa and Asia is quite low. Obesity, a major risk factor, likely relates to insulin resistance (the metabolic syndrome). Evolution and circumstance in American Indians may have ironically selected those with "thrifty" genes that conserve energy. Our abundant access to food places us at the increased risk of obesity and cholelithiasis. The general rise in obesity in many countries raises the specter of heightened disease, best identified by epidemiologic studies.

Deoxycholic acid is not related to lithogenic factors in gallbladder bile

The influence of deoxycholic acid (DCA) on the factors in gallbladder bile responsible for cholesterol gallstone disease has been a controversial subject of discussion. This might be partially due to patient selection or inappropriate methods. Therefore, we investigated the relationship between the percentage of DCA and lithogenic factors in the gallbladder bile of patients with cholesterol gallstones and with normal or moderately impaired gallbladder contractility. Patients with pigment stones served as a control group. The percentage of DCA in the gallbladder bile of 20 patients with cholesterol stones (23.2%+/-6.5%; mean+/-SD) was comparable to the DCA percentage in the gallbladder bile of 11 patients with pigment stones (26.5%+/-8.5%). No correlation was seen between the DCA percentage of total bile acids and the crystal observation time, cholesterol saturation index (CSI), total protein value, mucin level, and amount of cholesterol in vesicles or crystals in the total group of patients or in the subgroups with cholesterol or pigment stones, respectively. The lack of correlation between DCA percentage and CSI was determined in native bile (r = 0.048) as well as in crystal-free bile after ultracentrifugation (r = 0.107). Our findings demonstrate that in patients with gallstones, the percentage of DCA in gallbladder bile is not related to any of the known biliary factors associated with cholesterol gallstone disease. We conclude that in patients with normal or moderately impaired gallbladder function, an elevated DCA level in the gallbladder bile is of minor pathophysiologic significance for the formation of cholesterol gallstones.

Bile composition in patients with ileal resection due to Crohn's disease

Patients with Crohn's disease (CD) have an increased risk of developing gallstones, but the mechanisms are unknown. In a previous study, we found a subnormal cholesterol saturation in the bile of patients with short ileal resections due to CD. The aim of this study was to test the hypothesis that (a) CD patients with a long ileal resection have an altered biliary composition and (b) that CD patients with short or long ileal resection have an increased content of bilirubin in their bile. Biliary lipid composition, cholesterol saturation, bile acid pattern, and bilirubin concentration were determined in fasting duodenal bile of 10 CD patients with long ileal resections and in 4 patients with short resections. Ten healthy subjects served as controls. Cholesterol saturation was significantly lower in those CD patients who had a long or short resection compared with the healthy subjects. Bile acid composition in the CD patients was characterized by a significant decrease in the deoxycholic acid fraction and a prominent increase in the ursodeoxycholic acid fraction. The bilirubin concentrations, expressed as micromoles of bilirubin per millimole bile acid, were 45-50% higher in patients who had a long or a short ileal resection compared with healthy controls. Based on these results, CD patients who had had an ileal resection seem not to be at an increased risk of cholesterol gallstone formation but rather at risk of developing pigment stones.

Gallbladder motility and cholecystokinin release during long-term enteral nutrition in patients with Crohn's disease

BACKGROUND

Gallbladder bile stasis during long-term continuous enteral feeding may contribute to the high prevalence of gallstones in patients with Crohn's disease. We therefore examined the effects of continuous enteral nutrition on gallbladder motility and cholecystokinin (CCK) release in six patients.

METHODS

Gallbladder volume was measured ultrasonographically for 12 h on days 1 (start), 8, 22 (6-h interruption of enteral feeding), 36, and 43 (end) of enteral feeding. Plasma CCK was assessed at several time points.

RESULTS

Initial fasting gallbladder volume was 19.3 +/- 4.5 (mean +/- SEM) ml, which decreased to 4.9 +/- 3.6 ml after start of feeding. CCK increased from 1.5 +/- 0.3 to 3.9 +/- 1.1 pmol/l. On days 8 and 36 the gallbladder was almost completely contracted, and CCK increased to 7.5 +/- 2.7 and 8.3 +/- 2.6 pmol/l, respectively. On days 22 and 43 gallbladder volume increased, and CCK decreased rapidly to fasting concentrations after interruption of feeding.

CONCLUSIONS

During continuous enteral nutrition the gallbladder is completely contracted, and CCK concentrations remain elevated. It is therefore unlikely that long-term enteral nutrition contributes to the increased prevalence of gallstones in patients with Crohn's disease.

Cholelithiasis and bile acid absorption after truncal vagotomy and gastroenterostomy

Gallbladder disease in the form of gallstones demonstrated by ultrasonography or previous cholecystectomy was found in 15 of 26 women of median age 69 (range 52-82) years who had had truncal vagotomy and gastroenterostomy performed a median of 27 (range 11-30) years previously, compared with eight of 31 healthy age- and sex-matched controls drawn from the community (P < 0.02). Bile acid malabsorption identified by retention of 23-selena, 25-homotaurocholate (75SeHCAT) occurred in only two of the 26 patients after vagotomy and there was no relationship between retention and the presence or absence of gallbladder disease. The serum concentration of 7 alpha-hydroxycholestenone, an indicator of bile acid turnover, was significantly lower in patients with gallbladder disease after vagotomy than in controls (mean(s.e.m.) 19.1(3.7) versus 31.4(4.4) ng/ml, P < 0.05). Bile acid malabsorption does not play a significant role in the pathogenesis of gallstones after vagotomy but decreased bile acid synthesis may be important. There is no correlation between retention of 75SeHCAT and 7 alpha-hydroxycholestenone levels in patients after vagotomy, indicating that bile acid synthesis and absorption are uncoupled in this situation.

Phospholipase activation and arachidonic acid release in intestinal epithelial cells from patients with Crohn's disease

A method for studying the mobilization of free arachidonic acid (AA) in viable isolated human intestinal epithelial cells has been developed and applied to the study of patients with Crohn's disease. Cells were isolated from morphologically unaffected parts of the distal ileum and incubated with 14C-AA; most of the incorporated 14C-AA was then found in phospholipids (mainly phosphatidylcholine) and in a pool of neutral lipids (mainly triacylglycerols). Cells from patients with Crohn's disease incorporated more 14C-AA into their neutral lipids than did cells from control patients. When the labeled cells were stimulated with phospholipase C from Clostridium perfringens or with the calcium ionophore A23187, they released significant amounts of AA, mainly from phosphatidylcholine. There was no difference between cells from Crohn patients and controls in the 14C-AA amounts released, but unstimulated and phospholipase C-stimulated cells from prednisolone-treated Crohn patients released less AA than cells from control patients. The A23187-stimulated AA release was completely inhibited by the phospholipase A2 inhibitor 4-bromophenacyl bromide, whereas the phospholipase C-stimulated release was not. These findings suggest that AA release in human small-intestinal epithelial cells may be caused by calcium-mediated phospholipase A2 activation or by products of microbial phospholipase C activity and that prednisolone reduces the mobilization of free AA in intestinal epithelial cells. They also illustrate the potential use of isolated epithelial cells for revealing mechanisms underlying AA release in the intestinal mucosa in different disease states.

Lipid metabolism in bile acid malabsorption

Malabsorption of bile acid increases cholesterol synthesis and activates hepatic LDL receptors which leads to enhanced elimination of cholesterol from the body. Interruption of enterohepatic circulation of bile acids may lead to a smaller bile acid pool, which, in turn, impairs cholesterol and fat absorption by reduced micellar solubilization. Together with reduced cholesterol absorption, the increased cholesterol loss as bile acids also reduces plasma cholesterol concentrations and the biliary cholesterol excretion, too. Diminished biliary cholesterol in bile acid malabsorption may contribute to the increased incidence of gallstones associated with ileal dysfunction. Malabsorption of bile acid leads to a fall in LDL-cholesterol concentration, and an increase of HDL-cholesterol concentration has been reported. VLDL-triglyceride concentrations are almost invariably raised. Enhanced cholesterol and bile acid synthesis in ileal dysfunction is reflected by raised concentrations of plasma cholesterol precursors, especially lathosterols, which can be used as an indicator of increased bile acid loss to faeces. Cholesterol absorption, in turn, correlates positively with plasma plant sterol concentrations levels and the ratio of lathosterols to campesterols can be used as a screening measurement for ileal dysfunction. Plasma fatty acid composition is also altered as a response to fat malabsorption associated with ileal dysfunction. The proportion of essential fatty acids is inversely correlated with faecal fat excretion and endogenous fatty acid synthesis is activated.

Bile composition after total proctocolectomy with interposed jejunal segment as neorectum

Changes of bile composition in gallbladder bile and serum chemistries were investigated in nine dogs after proctocolectomy and ileoanal anastomosis, using an interposed jejunal segment as a neorectum. A significant decrease in cholic acid and an increase in deoxycholic acid were observed 24 weeks after the operation, although there was no significant change of total bile acid and phospholipids in the bile. Concentration of cholesterol and cholesterol saturation index in bile increased after total proctocolectomy. Although serum triglyceride levels became lower compared with the nontreated control group, concentrations of total protein, serum cholesterol, total lipids, blood sugar, and electrolytes showed no significant difference. This operative procedure apparently did not impair intestinal absorption of bile acid, but did increase the biliary cholesterol saturation index.

Role of primary and secondary bile acids as feedback inhibitors of bile acid synthesis in the rat in vivo

The effect of various primary and secondary bile acids on the rates of synthesis of all major bile acids was studied in the live rat with an extracorporal bile duct. Bile acid synthesis was determined using HPLC based on mass or by isotope dilution. Derepressed rates of bile acid synthesis (30-54 h) were inhibited by an infusion of taurocholic acid only at a supraphysiological dose of 500 mumol/kg per h, but not at 300 mumol/kg per h, which approximates the initial bile acid secretion (250 mumol/kg per h). When administered together with taurocholic acid (200 mumol/kg per h) only a high dose of taurochenodeoxycholic acid (100 mumol/kg per h) decreased taurocholic but not tauromuricholic or taurochenodeoxycholic acid synthesis. The only bile acid suppressing taurocholic acid (36-71%) and taurochenodeoxycholic acid (up to 33%) formation at an infusion rate close to the normal portal flux was deoxy- or taurodeoxycholic acid at 15-50 mumol/kg per h. It may be concluded that deoxycholic acid and possibly other secondary bile acids are much more potent inhibitors than primary bile acids.

Healing, relapse rates and prophylaxis of reflux esophagitis

Gastroesophageal reflux is a daily occurrence in the general population. Reflux esophagitis is less common but still a considerable clinical problem. The results of medical therapy are generally clearly inferior to those seen in peptic ulcer disease. After healing relapse is rapid and maintenance has not been proved superior to placebo. The promising results with omeprazole (inducing pronounced acid inhibition) and surgery (strengthening anti-reflux mechanisms) indicate that a more aggressive approach may be needed in future treatment. Additional studies also using combinations of drugs both in the healing stage and during maintenance is needed. These should be compared to the long-term results of surgery.

Lactosylceramide in inflammatory bowel disease: a biochemical study

A simple technique for isolating lipids from small pieces of tissue was applied to mucosal biopsies and samples of resected intestine from patients with inflammatory bowel disease. Scanning densitometry of two dimensional chromatograms showed increased concentrations of the membrane associated glycosphingolipid lactosylceramide in Crohn's disease, on comparison with ulcerative colitis (p less than 0.01), or controls (p less than 0.01). This indicates either that normal glycosphingolipid metabolism is altered, or that a novel source of lactosylceramide is present in the inflamed mucosa of patients with Crohn's disease.

Effects of partial ileocolectomy and Crohn's disease on biliary lipid secretion

The effects of interruption of the enterohepatic circulation of bile acids on biliary lipid secretion have only been studied experimentally, and quantitative data in patients are lacking. Therefore, biliary lipid secretion during steady-state meal perfusion of the duodenum was studied in six patients with partial ileocolectomy, five patients with Crohn's disease, and five normal subjects. Bile acid outputs in the resection patients were significantly lower than in normal controls, (6.87 +/- 2.10 mmol/6 hr and 13.5 +/- 2.16, respectively; P less than 0.001) and were also decreased in two of the five Crohn's disease patients. Bile acid outputs in patients with resection progressively decreased in the course of the perfusion study; phospholipid and cholesterol secretion did not decrease to the same extent, and cholesterol saturation gradually increased. Bile of these patients, therefore, was frequently supersaturated due to uncoupling of bile acid secretion and outputs of the other biliary lipids. Bile acid outputs, although decreased, did not reach very low values, which shows that the enterohepatic circulation was not totally interrupted. Chenodeoxycholic acid was the main bile acid component of bile in patients with ileocolonic resection. Deoxycholic acid was absent from bile of four resected patients and two Crohn's patients. Two patients with active Crohn's disease had low bile acid outputs despite only moderate fecal bile acid losses. Therefore, decreased outputs may be caused by decreased bile acid pool not compensated for by increased bile acid synthesis in severely ill patients.