Endocannabinoid Levels in Ulcerative Colitis Patients Correlate With Clinical Parameters and Are Affected by Cannabis Consumption

BACKGROUND

Inflammatory bowel diseases (IBDs) are chronic, idiopathic, inflammatory, gastrointestinal disorders. The endocannabinoid system may have a role in the pathogenesis of IBD. We aimed to assess whether cannabis treatment influences endocannabinoids (eCBs) level and clinical symptoms of IBD patients.

METHODS

Blood samples and biopsies were taken from IBD patients treated by either cannabis or placebo for 8 weeks. Immunohistochemistry for N-acyl-phosphatidylethanolamine-selective phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH) expression was done on colon biopsies, and sample levels of anandamide (AEA), eCB2-arachidonylglycerol (2-AG), arachidonic acid (AA), palmitoylethanolamine (PEA), and oleoylethanolamine (OEA) were measured in patient's sera before and after cannabis treatment. Caco-2 cells were cultured with extracts of cannabis with/without tetrahydrocannabinol (THC) and their proteins extracted, and Western blotting for NAPE-PLD and FAAH expression was done.

RESULTS

Thirteen patients with Crohn's disease (CD) and nine patients with ulcerative colitis (UC) were treated with cannabis. Seventeen patients with CD and 10 with UC served as placebo groups. In all CD patients, the levels of eCBs remained unaltered during the treatment period. In UC patients treated with placebo, but not in those treated with cannabis, the levels of PEA, AEA, and AA decreased significantly. The percent reduction in bowel movements was negatively correlated with changes observed in the circulating AEA and OEA, whereas improvement in quality of life was positively correlated with the levels of 2-AG. In the biopsies from UC patients, FAAH levels increased over the study period. In Caco-2 cells, both cannabis extracts increased NAPE-PLD levels but reduced FAAH expression levels.

CONCLUSION

Our study supports the notion that cannabis use affects eCB "tone" in UC patients and may have beneficial effects on disease symptoms in UC patients.

Telomere Length, Aggregates, and Capture in Cirrhosis

BACKGROUND

Shortened telomeres were found in patients with cirrhosis, probably reflecting chronic liver injury, continuous regeneration, and destruction of hepatic nodules.

OBJECTIVES

To test whether telomere shortening is a general marker of cirrhosis, independent of disease etiology.

METHODS

We evaluated telomere length in patients with cryptogenic cirrhosis (largely a late sequela of steatohepatitis) compared to patients with cirrhosis caused by chronic hepatitis B and C (HBV/HCV). We also evaluated telomere aggregates, a sensitive parameter of telomere dysfunction and genetic instability. We analyzed peripheral lymphocytes from 25 patients with cryptogenic cirrhosis, 15 patients with cirrhosis due to chronic viral hepatitis, and 20 age-matched controls. Telomere length was analyzed using quantitative fluorescence in situ hybridization. Aggregate size was divided into three fusion groups of 2-5, 6-10, and 11-15 telomeres, relative to the size of a single telomere.

RESULTS

Shorter telomere length was found in patients with cirrhosis from all three etiologies (mean 121.3 ± 24.1) compared to controls (mean 63.5 ± 23.5). In contrast, there was significantly more fusion of > 5 telomeres only in the HBV/HCV cirrhosis group compared to healthy controls (P = 0.023), but not in the cryptogenic cirrhosis group.

CONCLUSIONS

While shortened telomeres in peripheral lymphocytes are a general marker of liver cirrhosis, telomere aggregates may signify a more sensitive genetic instability parameter for the diverse, etiology-based malignant potential of cirrhosis. This finding is in agreement with the well-known higher tendency toward developing hepatocellular carcinoma with cirrhosis caused by chronic hepatitis relative to steatohepatitis.

Asynchronous Replication in Lymphocytes from Patients with Inflammatory Bowel Disease and Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) are associated chronic inflammatory diseases with malignant potential. Loss of replication synchrony during the S-phase of the cell cycle has been shown to be linked to several malignant and premalignant states. This study evaluated temporal differences in replication timing between these diseases. The replication pattern of peripheral blood lymphocytes obtained from patients with PSC and IBD and healthy individuals was analyzed by fluorescence in situ hybridization (FISH) in 2 pairs of alleles, in 15qter and 13qter. Asynchrony was determined by the presence of 1 single and 1 set of double dots in the same cell. Samples from subjects with PSC showed significantly greater temporal differences in replication timing, in contrast to the high level of synchrony observed in samples from healthy individuals (p = 0.045). Samples from IBD patients exhibited a nonsignificant increase in replication asynchrony. We believe that these results reflect impairment in the replication control of structural homologous loci in PSC, and that this phenomenon may be correlated with the inflammation-induced malignant potential of this condition.

Prognosis of primary sclerosing cholangitis in israel is independent of coexisting inflammatory bowel Disease

BACKGROUND AND AIMS

Primary sclerosing cholangitis (PSC) is a rare chronic progressive cholestatic disorder. We assessed its characteristics and natural history in Israel and compared its outcome with respect to coexisting inflammatory bowel disease (IBD).

METHODS

Data on characteristics, course and outcome were retrospectively retrieved on patients diagnosed with PSC from five large Israeli medical centers between 1988 and 2012. Patients with isolated PSC were compared with those with coexisting IBD to identify predictors of outcome.

RESULTS

Of 141 patients (56% males) with confirmed PSC, 98 (69.5%) had coexisting IBD. The average age at presentation was 38.8 ± 15.4 years and duration of follow-up was 7.93 ± 6.26 years. The crude estimated point prevalence was 4 cases per 105 persons. Demographics and clinical characteristics were similar among all patients except for symptoms at diagnosis (which were more prevalent among PSC–IBD patients) and utilization of multiple diagnostic modalities (which was more prevalent among isolated-PSC patients). More than one-third of the entire cohort had cirrhosis. A total of 15 patients (10.6%) died and 19 patients (13.5%) developed malignancy during follow-up. Nine patients (6.3%) underwent liver transplantation. Mean survival for the entire cohort was 26.3 ± 1.4 years and mean transplant-free survival was 23.5 ± 1.6 years. Cox proportional hazard regression for transplantation or death revealed two independent risk factors: cirrhosis and malignancy [hazard ratio 4.25 (p = 0.004) and 2.58 (p = 0.046), respectively].

CONCLUSIONS

Survival rate of PSC patients in Israel is longer than reported rates worldwide and is independent of coexisting IBD.

Dietary enrichment with alpha-linolenic acid during pregnancy attenuates insulin resistance in adult offspring in mice

OBJECTIVE

Our objective was to test the contribution of dietary enrichment in essential or saturated fatty acids, in normocaloric diets, on the lipid accumulation and insulin resistance in the adult offspring in a C57Bl6/J mice model.

METHODS

Pregnant mothers were fed normocaloric diets containing 6% fat enriched in essential fatty acids (EFA): alpha-linolenic (ALA-18:3, n-3), linoleic (LA-18:2, n-6), or saturated fatty acids (SFA). After a washing-out period with regular diet, the offspring received a high-fat diet before euthanization.

RESULTS

Adult mice fed maternal ALA showed lower body weight gain and lower liver fat accumulation, lower HOMA index and lower stearoyl-CoA desaturase (SCD1) activity than those fed maternal SFA.

CONCLUSION

The results observed using this novel model suggest that ALA in maternal diet may have the potential to inhibit insulin resistance in adult offspring.

Ziziphus jujuba extract for the treatment of chronic idiopathic constipation: a controlled clinical trial

PURPOSE

To investigate the safety and efficacy of an extract of Ziziphus jujuba for chronic constipation.Constipated patients received liquid Z. jujuba or placebo for 12 weeks. Subjects completed questionnaires, a visual analog scale and transit time (TT) tests before and after treatment.

RESULTS

Of 37 patients with a prolonged TT, 18 received the study drug and 19 a placebo. Two (12%) of the study and 16 (84%) of the control group dropped out due to severe constipation. The TT decreased from 12.2 particles for the study group to 3 particles at week 11. Symptom severity ratings decreased from 6 and 6.2 to 2 and 5, and the quality of life score improved from 1.9 and 2.3 to 1.3 and 1.4 in the study and control groups, respectively.

CONCLUSION

Z. jujuba extract is an effective and safe treatment for chronic constipation.

Nonspecific esophageal motility disorders may be an early stage of a specific disorder, particularly achalasia

The clinical significance of nonspecific esophageal motility disorder (NEMD) is unclear. Our aim was to investigate the natural history of NEMD. All manometries performed at Meir Hospital from 1997 to 2004 and diagnosed as NEMD were reviewed. Manometric criteria for NEMD included either low-amplitude peristalsis, nonprogression of peristalsis, prolonged retrograde or triple-peaked waves, or incomplete relaxation of the lower sphincter. Patients determined to have NEMD were contacted and asked to complete a questionnaire and undergo a second manometry. NEMD had been diagnosed in 137 patients. Upon review of manometry results, 65 patients were eligible for the study (36 men and 29 women). The other 72 patients did not have NEMD when we reviewed their manometry tracing, applying strict criteria as specified in Table 1. The average age was 64 +/- 16 years (range 24-83 years). The average follow-up period was 7 +/- 2 years. All 65 patients were symptomatic at their initial prestudy visit. By the second visit, symptoms had resolved in 33 (51%) patients and improved in 13 (19%). Dysphagia, chest pain, and food regurgitation had improved, whereas heartburn and respiratory symptoms had not. Of 37 patients with triple-peaked waves, only 11 (30%) had improved clinically. Of the 65 study patients, 17 (26%) had a second manometry during the study, which was normal in 2 (12%), unchanged in 11 (69%), and revealed achalasia in 4 (23%), representing 6% of all study patients. NEMD is generally a benign disorder that improves clinically in most cases. Nevertheless, in about 6% of patients, NEMD may evolve into achalasia.

The clinical significance of bile duct sludge: is it different from bile duct stones?

BACKGROUND

Some patients with suspected common bile duct (CBD) stones are found to have sludge and no stones. Although sludge in the gallbladder is a precursor of gallbladder stones, the significance of bile duct sludge (BDS) is poorly defined. This study aimed to compare BDS with bile duct stones in terms of frequency, associated risk factors, and clinical outcome after endoscopic therapy.

METHODS

The study enrolled 228 patients who underwent therapeutic endoscopic retrograde cholangiopancreatography (ERCP) for suspected choledocholithiasis. The patients were divided into two groups: patients with BDS but no stones on ERCP and patients with CBD stones. The presence of risk factors for bile duct stones (age, periampullary diverticulum, ductal dilation or angulation, previous open cholecystectomy) were assessed at ERCP. Follow-up data (36 +/- 19 months) were obtained from medical records and by patient questioning.

RESULTS

Bile duct sludge occurred in 14% (31/228) of patients and was more common in females. After endoscopic clearance, CBD stones recurred in 17% (33/197) of the patients with CBD stones, and in 16% (5/31) of the patients with BDS (p = 0.99). Common bile duct dilation was less common in the sludge group. The other known risk factors for recurrent CBD stones (age, previous open cholecystectomy, bile duct angulation, and the presence of a peripampullary diverticulum) were not statistically different between the two groups.

CONCLUSIONS

The findings indicate that the clinical significance of symptomatic BDS is similar to that of CBD stones. Bile duct sludge seems to be an early stage of choledocholithiasis.

An angulated common bile duct predisposes to recurrent symptomatic bile duct stones after endoscopic stone extraction

BACKGROUND

Endoscopic sphincterotomy and stone extraction are standard procedures for the removal of bile duct stones. Stone recurrence can, however, occur in up to 25% of cases. Risk factors have been poorly defined, but are believed to be related to bile stasis. This study investigated whether an angulated common bile duct (CBD) that may predispose to bile stasis influences symptomatic stone recurrence after successful endoscopic therapy.

METHODS

This study included 232 consecutive patients (mean age, 64.1 years; 86 men) who had undergone therapeutic endoscopic retrograde cholangiopancreatography for bile duct stones. Data from the follow-up period (36 +/- 17 months) were obtained from medical records and patient questioning. Common bile duct angulation and diameter were measured from the cholangiogram after stone removal.

RESULTS

Symptomatic bile duct stones recurred in 16% of the patients (36/232). Three independent risk factors were identified by multivariate analysis: an angulated CBD (angle, < or = 145 degrees; relative risk [RR], 5.2; 95% confidence interval [CI], 2.2-12.5; p = 0.0002), a dilated CBD (diameter, > or = 13 mm; RR, 2.6; 95% CI, 1.2-5.7; p = 0.017), and a previous open cholecystectomy (RR, 2.7; 95% CI, 1.3-5.9; p = 0.0117). Gender, age, urgency of procedure, or a periampullary diverticulum did not influence the recurrence rate.

CONCLUSIONS

Angulation of the CBD (< or = 145 degrees) on endoscopic cholangiography, a dilated CBD, and a previous open cholecystectomy are independent risk factors for symptomatic recurrence of bile duct stones. The findings support the role of bile stasis in stone recurrence. Further studies using these data prospectively to identify high-risk patients are warranted.

Endoscopic sphincterotomy and temporary internal stenting for bile leaks following complex hepatic trauma

Background

Biliary leak secondary to blunt or penetrating hepatic trauma and damage to the intrahepatic biliary tree remains a challenging problem. The role and safety of endoscopic retrograde cholangiopancreatography (ERCP) and stenting in this setting were studied.

Methods

All trauma victims who developed a bile leak secondary to hepatic trauma were included. Bile leak was defined as the appearance of bile in a surgical wound or intra-abdominal drain after surgery, following percutaneous drainage of a perihepatic bile collection, or evidence of a leak on hepatobiliary scintigraphy. ERCP was performed within 24 h of diagnosis and included biliary sphincterotomy and internal stenting. Recovery was defined as cessation of leakage.

Results

Between 1996 and 2004, six patients with penetrating injuries and five with blunt abdominal injuries were treated according to the study protocol. Eight underwent surgery to control bleeding or for additional intra-abdominal injuries. All bile leaks resolved completely within 10 days of ERCP. One patient died from pulmonary sepsis; ten recovered without hepatobiliary sequelae.

Conclusion

ERCP, biliary sphincterotomy and temporary internal stenting, together with percutaneous drainage of intra-abdominal or intrahepatic bile collections, represent a safe and effective strategy for the management of bile leaks following both blunt and penetrating hepatic trauma.

Faecal sterol output is increased by arachidyl amido cholanoic acid (Aramchol) in rats

Fatty acid-bile acid conjugates (FABACs) were shown recently to have important and multiple effects on cholesterol metabolism. In human fibroblasts, they were found to markedly enhance cholesterol efflux by an ATP-binding cassette transporter A1-dependent pathway. In C57L/J mice, they increased CYP7A1 activity and RNA expression, while decreasing moderately 3-hydroxy-3-methylglutaryl-CoA reductase activity. In C57L/J mice and in hamsters, they also decreased serum cholesterol levels, whereas in other animals, this effect was not seen in short-term experiments. In the present study, we investigated potential mechanisms of action of arachidyl amido cholanoic acid (Aramchol), with particular reference to biliary and faecal sterol outputs in rats. Supplementation with Aramchol at a dose of 150 mg x kg(-1) x day(-1) increased neutral sterol output by approx. 50%, while the faecal outputs of bile salts and total sterols increased by almost 2-fold. Biliary lipid outputs were not significantly different between the control and FABAC-supplemented animals. These findings indicate an overall catabolic effect of FABACs on body cholesterol.

Arachidyl amido cholanoic acid (Aramchol) is a cholesterol solubilizer and prevents the formation of cholesterol gallstones in inbred mice

We have recently synthesized fatty acid bile acid conjugates (FABAC) that were able to reduce and retard cholesterol crystallization in model and human biles. When given orally, they prevented the formation of cholesterol crystals in the bile of hamsters. The aim of the present study was to determine whether the FABAC are cholesterol solubilizers, whether they can dissolve pre-existing crystals, whether they can prevent the formation of cholesterol gallstones, and to investigate the optimal type of bond between the fatty acid and bile acid. The presence of cholesterol crystals was determined by light microscopy, and the total crystal mass of precipitated crystals was measured by chemical means. Inbred (C57J/L) mice on a lithogenic diet were used to evaluate cholesterol crystal formation, dissolution, and gallstone formation in vivo. Arachidyl amido cholanoic acid (Aramchol) was the FABAC used in the present experiments. At equimolar amounts, the cholesterol-solubilizing capacity of Aramchol was higher than that of taurocholate and similar to that of phosphatidylcholine. The addition of Aramchol dissolved approximately 50% of pre-existing crystals in model bile solutions. The same phenomenon was demonstrated in human bile ex vivo, with a dose-response effect. All inbred mice developed cholesterol crystals in bile after 10-14 d on the lithogenic diet. Thereafter, supplementation of the diet with Aramchol progressively reduced the proportion of mice with crystals to 25% after 28 d. On the lithogenic diet, 100% of inbred mice developed cholesterol gallstones in the gallbladder by day 21. None of the mice whose diet was supplemented with 0.5 mg or 1.0 mg of Aramchol/d developed stones or crystals. FABAC are a new class of molecules that are cholesterol solubilizers and which are able to dissolve cholesterol crystals in bile. Upon oral administration, they dissolve pre-existing cholesterol crystals and prevent the formation of gallstones in gallstone-susceptible mice.

Cytokine network in nonresponding chronic hepatitis C patients with genotype 1: role of triple therapy with interferon alpha, ribavirin, and ursodeoxycholate

OBJECTIVE

(i) to characterize the profile of tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), IL 10, Fas-ligand and transforming growth factor beta (TGF beta), chronic hepatitis C (HCV) patients with genotype 1; (ii) to determine the influence of triple therapy (TT) with interferon alpha (IFN alpha) + ribavirin + ursodeoxycholic acid on these cytokines and (iii) to establish the relationship between the pro-inflammatory cytokines and the outcome of treatment.

DESIGN AND METHODS

22 patients infected with HCV-genotype 1 a/b and non responsive to IFN-alpha monotherapy were enrolled in the TT. The controls were 49 HCV naïve patients with genotype 1 a/b. Cytokine levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The baseline TNF alpha values (pg/mL) in the sustained responders (SRs) (63+/-3) were significantly lower than non-responders (NRs) (140+/-16) (p < 0.001). Baseline Fas (ng/mL) levels were also lower in SRs (4.3+/-0.2) than NRs (5.4+/-0.4) (p < 0.05).

CONCLUSIONS

Fas and TNF alpha may be used as serological markers of inflammation and effectiveness of therapy.

Additive deleterious effect of smoking on gastroduodenal pathology and clinical course in Helicobacter pylori-positive dyspeptic patients

BACKGROUND

Cigarette smoking has long been regarded as an important factor in the pathogenesis of peptic ulcer disease.

OBJECTIVE

To investigate whether cigarette smoking has an additive effect on the clinical presentation and course of disease in Helicobacter pylori-positive dyspeptic patients.

PATIENTS AND METHODS

The study group comprised 596 consecutive H. pylori-positive dyspeptic patients (334 males and 262 females, mean age 50.6, range 12-81 years). Following upper gastrointestinal endoscopy, patients were subdivided by diagnosis as follows: Non-ulcer patient group (n = 312: gastritis 193, duodenitis 119), gastric ulcer (n = 19), and duodenal ulcer (n = 265). H. pylori infection was confirmed by histology and/or rapid urease test. In addition, 244 patients had a positive 14C-urea breath test prior to antimicrobial treatment. The patients' medical history and smoking habits were obtained using a detailed questionnaire completed by the patients and their referring physicians.

RESULTS

There were 337 non-smoking patients, 148 current smokers and 111 past smokers. Gastric and duodenal ulcers were significantly less prevalent in non-smokers than in current or past smokers (gastric 1.8%, 4.1%, 6.3%; duodenal 39.8%, 50%, 51.4%, respectively) (P < 0.05). The incidence of gastrointestinal bleeding was significantly lower in non-smokers than in current or past smokers (7.1%, 8.1% and 20.7%, respectively) (P < 0.05). Bacterial density, as assessed by the UBT value in 244 patients, was higher in non-smokers (mean 352.3 +/- 273 units) than in past smokers (mean 320.8 +/- 199) or current-smokers (mean 229.9 +/- 162) (P < 0.05). Logistic regression analysis revealed that male gender, current smoking, and immigration from developing countries were all significant independent risks for developing duodenal ulcer, while only past smoking was associated with a higher rate of upper gastrointestinal bleeding in the past.

CONCLUSIONS

In H. pylori-positive dyspeptic patients, current smoking as well as male gender and immigration from developing countries are associated with an increased risk for duodenal ulcer. This effect does not seem to be related to the bacterial density or increased urease activity of H. pylori organisms.

Microstructural analysis of bile: relevance to cholesterol gallstone pathogenesis

The study of physical-chemical factors and pathways leading to cholesterol crystallization in bile has important clinical relevance. The major processes in cholesterol gallstone formation can be subdivided into nucleation, formation and precipitation of solid crystals (crystallization), crystal growth, crystal agglomeration and stone growth. A clear understanding of the microstructural events occurring during the earliest stages of these processes in bile is crucial for the identification of factors possibly delaying or preventing precipitation of cholesterol crystals and, therefore, gallstone formation in bile. Detection and characterization of microstructures in native and model biles can be achieved by both direct and indirect techniques. Direct imaging techniques provide more readily interpretable information, but sample preparation problems, particularly for electron microscopy, are a source of artifacts. Moreover, microscopic techniques provide only qualitative data without the possibility to quantitate or to analyse the composition of microstructures. Several indirect techniques have been used to obtain additional microstructural information about nucleating bile. These techniques have the disadvantage of often being model dependent in addition to constraints specific for each method. The systematic, judicious use of a combination of complementary direct and indirect techniques have led to a comprehensive understanding of the various microstructural processes and interactions occurring during bile secretion, flow in the biliary tract and storage in the gallbladder. This forms the basis for our current understanding of cholesterol nucleation, crystallization and gallstone formation.

Microstructural evolution of lipid aggregates in nucleating model and human biles visualized by cryogenic transmission electron microscopy

Obtaining reliable information on the physical state and ultrastructure of bile is difficult because of its mixed aqueous-lipid composition and thermodynamic metastability. We have used time-lapse cryogenic transmission electron microscopy (cryo-TEM) combined with video-enhanced light microscopy (VELM) to study microstructural evolution in nucleating bile. A well-characterized model bile and gallbladder biles from cholesterol and pigment gallstone patients were studied sequentially during cholesterol nucleation and precipitation. In model bile, cholesterol crystallization was preceded by the appearance of the following distinct microstructures: spheroidal micelles (3-5 nm), discoidal membrane patches (50-150 nm) often in multiple layers (2-10), discs (50-100 nm), and unilamellar (50-200 nm) and larger multilamellar vesicles (MLVs). The membrane patches and discs appeared to be short-lived intermediates in a micelle-to-vesicle transition. Vesicular structures formed by growth and closure of patches as well as by budding off from vesicles with fewer bilayers. MLVs became more abundant, uniform, and concentric as a function of time. In native bile, all the above microstructures, except discoidal membrane patches, were observed. However, native MLVs were more uniform and concentric from the beginning. When cholesterol crystals appeared by light microscopy, MLVs were always detected by cryo-TEM. Edges of early cholesterol crystals were lined up with micelles and MLVs in a way suggesting an active role in feeding crystal growth from these microstructures. These findings, for the first time documented by cryo-TEM in human bile, provide a microstructural framework that can serve as a basis for investigation of specific factors that influence biliary cholesterol nucleation and crystal formation.

The effects of short term lipid infusion on plasma and hepatic bile lipids in humans

BACKGROUND

Patients on parenteral nutrition have an increased incidence of gall bladder sludge and gallstone disease, thought to be related to bile stasis. Intravenous lipid emulsions, especially those containing medium chain triglycerides, have also been shown to have a lithogenic effect on the composition of bile in the gall bladder.

AIMS

To determine whether lipid infusion influences hepatic bile composition in patients with an indwelling T tube following cholecystectomy and choledochotomy.

METHODS

In eight patients undergoing the above surgical procedure, the time at which effects of the interrupted enterohepatic circulation were minimal was determined. Twenty two cholesterol gallstone patients with bile fistula were then randomised to receive an infusion of a lipid emulsion containing either long chain triglycerides or a mixture of long and medium chain triglycerides.

RESULTS

Lipid infusion resulted in a significant increase in plasma levels of triglycerides and phospholipids. Both lipid emulsions caused an increase in hepatic biliary cholesterol level and cholesterol saturation index, but this effect was more pronounced with medium chain triglycerides. The fatty acid composition of biliary phospholipids showed a significant enrichment of linoleic acid by both lipid infusions.

CONCLUSIONS

Infusion of triglycerides causes lithogenic changes in hepatic bile composition in humans, the lithogenic effect of infusion of medium chain triglycerides being more pronounced than that of long chain triglycerides. This effect, coupled with gall bladder stasis, may be responsible for the increased risk of biliary sludge and gallstone formation in patients on long term lipid infusion.

The efficacy of omeprazole-based short-term triple therapy in Helicobacter pylori-positive older patients with dyspepsia

OBJECTIVE

To evaluate the efficacy of 1-week triple therapy with omeprazole, clarithromycin,and tinidazole (OCT) in Helicobacter pylori-positive older patients with dyspepsia.

DESIGN

A prospective, nonrandomized therapeutic study.

SETTING

The primary care and referral center of a gastroenterological outpatient clinic at a central university hospital serving an urban population (>1 million) in Israel.

PARTICIPANTS

The study group consisted of 134 patients (71 men, and 63 women) more than 60 years old who were referred for evaluation of symptoms of dyspepsia and were endoscopically diagnosed as H. pylori positive. The patients were divided into two groups: those who received their first course of anti-H. Pylori therapy during this study (Group 1) and those who had previously received standard metronidazole and bismuth combination therapies that failed to eradicate the H. pylori (Group 2).

MEASUREMENTS

All the patients underwent upper gastrointestinal endoscopy, and H. pylori infection was confirmed by a rapid urease test (CUTest) and/or histological staining. Therapeutic efficacy was assessed by a 13C-urea breath test 4 weeks after completion of treatment.

RESULTS

The mean age of the study population was 68.8 years (range 60-87). There were 112 patients in Group 1 and 22 patients in Group 2. Endoscopic findings were: gastritis (in 46), gastric ulcer (8), duodenal ulcer (52), and duodenitis (28). The H. pylori eradication rate was significantly higher in Group 1 patients (104/112, 92.9%) than in patients of Group 2 (15/22, 68.2%). There was no difference in the eradication rate in relation to gender, endoscopic diagnosis, more advanced age, place of birth, or smoking habits. The compliance in both groups was equally good, and no major side effects were recorded.

CONCLUSIONS

A 1-week OCT triple therapy is well tolerated and effective as first line therapy for H. pylori among older people. It is less effective in patients previously treated.

Decreased fecal bile acid output in patients with coronary atherosclerosis

In most patients with atherosclerosis, the underlying metabolic derangement remains undefined. Animal experiments have suggested that the ability to produce and excrete large amounts of bile acids may be an adaptation mechanism to cholesterol overload protecting against the atherogenic effects of cholesterol. However, there are very few data on bile acid excretion in human atherosclerosis. In the present study, we have investigated fecal bile acid secretion in subjects with and without coronary artery disease. The target group consisted of 30 patients with proven coronary artery disease and the control group consisted of 27 matched subjects without clinical or laboratory evidence of coronary atherosclerosis. Fecal bile acids were measured by gas-liquid chromatography from 24-hr stool collections under a controlled diet. The patients excreted significantly less bile acids than the controls (325+/-135 vs. 592+/-223 mg/day, respectively, p < 0.0001). The difference was primarily due to a reduced excretion of secondary bile acids. Less than 50% of deoxycholate was excreted by patients (180+/-81 mg/day) as compared to controls (367+/-168 mg/day, p < 0.0002), while lithocholic acid excretion was 111+/-62 mg/day in patients vs. 190 +/-70 mg/day in controls (p < 0.005). The fecal output of the two primary bile acids, cholic and chenodeoxycholic acid, did not differ significantly between patients and controls. The fecal output of total bile acids correlated with that of both secondary bile acids in patients as well as in controls. These findings suggest that patients with coronary heart disease are unable to excrete adequate amounts of bile acids to rid themselves of excess cholesterol, even if they are able to maintain a plasma cholesterol level comparable to that of healthy controls.

The effects of phospholipid molecular species on cholesterol crystallization in model biles: the influence of phospholipid head groups

BACKGROUND/AIMS

Variations in the molecular species of biliary phospholipids have been shown to exert major effects on cholesterol solubility and carriers in model and human biles. The aim of this study was to explore systematically the effects of various phospholipid head groups on the cholesterol crystallization process in model biles.

METHODS

Three different control model biles were prepared using varying proportions of egg lecithin, cholesterol and Na taurocholate. In the test biles, 20% of the egg lecithin was replaced with synthetic phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol or phosphatidylcholine, keeping the phospholipid acyl chains and other biliary lipids constant in each experiment.

RESULTS

Phosphatidylserine and phosphatidylglycerol significantly prolonged the crystal observation time, from 2 days to 10 and 6 days, respectively (p<0.02), while phosphatidylethanolamine had little and phosphatidylcholine no effect. The crystal growth rate was significantly slowed down with 20% phospholipid replacement in the following order: phosphatidylglycerol >phosphatidylserine >phosphatidylethanolamine. The total crystal mass after 14 days, as measured by chemical analysis, was reduced by 59% with phosphatidylserine (p<0.05), and by 73% with phosphatidylglycerol (p<0.05); while phosphatidylethanolamine had little effect. The precipitable cholesterol crystal fractions after 14 days were significantly reduced with phosphatidylserine (54%) and phosphatidylglycerol (37%), but not with phosphatidylethanolamine or phosphatidylcholine.

CONCLUSIONS

Variations in the head groups of biliary phospholipids may markedly slow down the cholesterol crystallization process in model biles.

Increased saturation of the fatty acids in the sn-2 position of phospholipids reduces cholesterol crystallization in model biles

Changes in the molecular structure of biliary phospholipids were shown to have major effects on cholesterol solubility, carriers and crystallization in human and model biles. This study investigated systematically the effects of varying saturation of the phosphatidylcholine (PC) sn-2 fatty acid on the cholesterol crystallization process in 3 different model biles. Twenty % of the egg PC (EPC) in these biles were replaced by synthetic PC's with 16:0-18:0, 16:0-18:1, or 16:0-18:2 fatty acyl chains. With 18:0 in the sn-2 position, the crystal observation time (COT) was prolonged from 2 days in the control EPC solution to 14 days (p<0.05). The crystal growth rate (CGR) was reduced from 0.1 OD/day to unmeasurable levels, and the total crystal mass on day 14 decreased by 86%. The introduction of one (18:1), and two (18:2) double bonds in the sn-2 fatty acid rapidly reversed these effects. Ultracentrifugal analysis showed precipitable cholesterol as monohydrate crystals. In the 16:0-18:0 test solution, most of the precipitable cholesterol remained in the supersaturated multilamellar vesicles. Saturation of the biliary PC sn-2 fatty acyl chain prolongs the COT, slows the CGR, reduces the crystal mass, and extends cholesterol solubility in multilamellar vesicles. Desaturation of the sn-2 fatty acid reverses these effects.

Imaging supramolecular aggregates in bile models and human bile

Investigation of cholesterol crystallization is essential for the understanding of gallstone formation. Previous work has revealed a variety of aggregates of different sizes and shapes prior to the appearance of "classical" plate-like cholesterol monohydrate crystals both in native biles and model systems. In this article, we review existing data based on various microscopic techniques and present data on microstructural pathways leading to cholesterol crystal formation in two different bile models and in native bile. In continuation of our recent investigation of microstructures in nucleating human bile, we now present data suggesting that polymorphism is not limited to complex native bile, but also appears in two, simplified model systems. These studies employed cryo-transmission electron microscopy (cryo-TEM) and video-enhanced light microscopy, using Nomarski optics (VELM). Only the combined use of these two complementary, non-perturbing direct methods can cover the whole range of microstructures ranging from a few nanometers to several microns. Concentrated isotropic solutions of bile models, composed of cholesterol, lecithin and taurocholate, were diluted to induce cholesterol supersaturation and start an evolution of microstructures, leading to cholesterol crystallization. Initially, small spheroidal micelles were observed by cryo-TEM. Subsequently, uni-, oligo- and multilamellar vesicles, compatible with structures seen at the same time by VELM, appeared in coexistence with micelles. Thereafter, during a dynamic phase of cholesterol crystallization, filaments, tubular and helical microstructures, as well as classical plate-like cholesterol monohydrate crystals were noted by light microscopy. Eventually, large plate-like crystals were observed by VELM, while cryo-TEM revealed only small spheroidal micelles. The crystallization process in native human bile during ex vivo incubation was found to bear close resemblance to the findings in the model systems, further supporting the applicability of these systems to the exploration of microstructural aspects of nucleating human bile.

Calcium and the anionic polypeptide fraction (APF) have opposing effects on cholesterol crystallization in model bile

BACKGROUND/AIMS

Cholesterol gallstones contain both calcium and biliary proteins, but their respective roles in gallstone pathogenesis are unknown. We have studied the effects of calcium and a major biliary protein, anionic polypeptide fraction, on the process of cholesterol crystallization in bile.

METHODS

Anionic polypeptide fraction was purified from human bile. Model bile composed of cholesterol, egg yolk lecithin and sodium taurocholate was prepared in a lipid concentration (18 mM, 37 mM, and 120 mM, respectively) simulating lithogenic human gallbladder bile. The crystallization process was observed by phase contrast light microscopy, and sequential separation of precipitable cholesterol structures by sucrose density gradient ultracentrifugation.

RESULTS

Addition of calcium, or anionic polypeptide fraction alone, or both together did not influence the crystal observation time of bile (the time which elapsed from initiation of supersaturation to the first appearance of crystals). However, the rate and quantity of cholesterol precipitation and crystal formation were affected by both. Calcium increased in a dose-dependent manner the cholesterol monohydrate crystal mass before apparent equilibrium was reached. This effect was inhibited by anionic polypeptide fraction, which increased the amount of cholesterol within precipitable phospholipid vesicles, and decreased the rate of crystal formation. Fluorescence-labeled anionic polypeptide fraction revealed that anionic polypeptide fraction (with and without calcium) was primarily associated with vesicle aggregates.

CONCLUSIONS

Our data demonstrate that calcium and anionic polypeptide fraction have opposing effects on the process of cholesterol crystallization and the resultant crystal mass without influencing the crystal observation time of bile. These findings suggest that biliary proteins, in addition to being crystallization effectors by themselves, may further influence cholesterol crystallization and gallstone formation by interacting with calcium and possibly other elements that coexist in bile.

The absorption of low-dose methotrexate in patients with inflammatory bowel disease

BACKGROUND

Recent clinical trials have demonstrated that methotrexate may have an important therapeutic role in the treatment of patients with inflammatory bowel disease, who are either refractory or intolerant to traditional medical therapy. The aim of this study was to evaluate the pharmacokinetics of low-dose oral methotrexate in patients with inflammatory bowel disease.

METHODS

Methotrexate (12.5 mg) was given orally to nine patients with inflammatory bowel disease: five with Crohn's disease, and four with ulcerative colitis, and to six patients with rheumatoid arthritis who served as a control group. Blood samples were drawn at specific intervals to evaluate methotrexate plasma levels.

RESULTS

Methotrexate was rapidly absorbed in all patients. Peak concentrations (Cmax) varied considerably, ranging from 0.25-0.87 micro M. The mean Cmax values were similar in all patient groups (0.59 +/- 0.12, 0.69 +/- 0.16 and 0.54 +/- 0.18 micro M, P not significant) for Crohn's disease, ulcerative colitis and rheumatoid arthritis, respectively. The mean area under curve in 120 min (AUC0-120) was also similar in all patient groups (32.9 + 11.3, 43.6 + 9.9 and 41.8 + 14.9 ng.min/mL, P not significant) for Crohn's disease, ulcerative colitis and rheumatoid arthritis, respectively. The mean time to reach Cmax, (tmax), varied between patient groups (84, 112 and 95 min, respectively, with a significant difference, P < 0.02, between the Crohn's disease and ulcerative colitis groups. A negative correlation was found between methotrexate dosage/kg and Cmax (r = -0.74) only in Crohn's disease patients but not in the other patient groups.

CONCLUSIONS

Orally administered methotrexate is well absorbed in patients with inflammatory bowel disease including those with severe small bowel disease or resection. If methotrexate is proven to be effective in inflammatory bowel disease, it should be administered orally.

A new method for the rapid measurement of cholesterol crystallization in model biles using a spectrophotometric microplate reader

Measurements of the cholesterol crystal observation time, and particularly the crystal growth rate in model biles, are important in biliary pathophysiology. The aim of this study was to develop a semi-automated method permitting multiple, simultaneous, and precise measurements of the crystal growth rate in model biles. Incubated model biles were mixed with a high concentration of NaTDC to solubilize non-crystalline turbidity and spectrophotometric measurements were performed. In parallel, samples were observed by light microscopy. The absorbance correlated linearly with the crystal mass and permitted quantitation of the crystal growth rate. Polarized light microscopy was more sensitive than spectrophotometry for determining the initial crystal observation time, while spectrophotometry was more precise and quantitative for measuring the crystal growth rate.

Monitoring cholesterol crystallization from lithogenic model bile by time-lapse density gradient ultracentrifugation

BACKGROUND/AIMS

Cholesterol crystallization in a dilute, bile salt-rich model bile is a multiphase process in which early filamentous crystals gradually transform to classical cholesterol monohydrate plates. The pertinence of similar transformations in more complex model systems or native bile is, however, unclear. The aim of the present study was to characterize and monitor cholesterol crystallization in a model bile of physiological relevance.

METHODS

A supersaturated model bile was prepared with a lipid composition (18 mM cholesterol, 37 mM lecithin, 120 mM taurocholate) that was derived from analyzing 10 gallbladder biles from cholesterol gallstone patients. Cholesterol crystallization was followed by light and electron microscopy, and sequential density gradient analysis of cholesterol-containing precipitates.

RESULTS

During cholesterol crystallization a reproducible sequence of events was recorded. First (T<18 h), cholesterol-rich vesicular and multilamellar structures (density 1.005-1.015 g/ml) were observed. Later, (T>60 h) filamentous, helical, tubular (density 1.015-1.04 g/ml) and plate-like (density 1.04-1.06 g/ml) cholesterol crystals appeared. The concentration of crystals increased gradually, while bilayer structures became desaturated with cholesterol and disappeared, and early crystal forms were replaced by plates. Eventually (T>25 days) only classical plate-like cholesterol monohydrate crystals were present. Exposure of cholesterol-containing precipitates to micellar (100 mM) deoxycholate dissolved the bilayer structures but not the crystals.

CONCLUSIONS

These data demonstrate that cholesterol crystallization in a physiologically relevant model bile is a multiphase process consisting of a sequence of transitions from vesicular and multilamellar structures to early crystal forms and to classical plate-like cholesterol monohydrate crystals. These transitions are associated with increasing density and decreasing phospholipid content of cholesterol precipitates. We suggest that time-lapse density gradient ultracentrifugation is a useful method for investigating and quantitating the process of cholesterol crystallization and factors that influence this process in bile.

One week triple therapy with omeprazole, clarithromycin and tinidazole for Helicobacter pylori: differing efficacy in previously treated and untreated patients

BACKGROUND

Triple therapy with omeprazole, clarithromycin, and tinidazole (OCT) has been found to be highly effective against Helicobacter pylori infection. However, its efficacy as a second line regimen for patients who failed metronidazole-based triple therapy has not been evaluated.

AIM

The aim of this study was to evaluate the efficacy of low-dose, short-term OCT therapy in an Israeli population, and to compare results obtained in previously treated and untreated patients.

METHODS

Patients with duodenal or gastric ulcers and chronic antral gastritis with H. pylori infection as assessed by rapid urease test and/or 14C urea breath test (14C-UBT), were studied. All patients received omeprazole 20 mg b.d., clarithromycin 250 mg b.d. and tinidazole 500 mg b.d. for 7 days. Eradication was assessed by 14C-UBT 4 weeks after treatment.

RESULTS

One hundred and fourty-four patients (M/F = 81/63) were enrolled (mean age 48.1 years, range 12-78). Eradication of H. pylori was significantly different between patients who were initially treated with this regimen (90/94, 96%) and patients who had previously failed to eradicate H. pylori with standard triple therapy (27/50, 54%). Moreover, the eradication rate was significantly decreased in patients with more than one previous failure (9/22, 41%) compared to that in patients with only one failure (18/29, 62%). No other differences such as age, gastric pathology, ethnic origin, smoking habits, or pre-treatment urease activity were found to influence the eradication rate.

CONCLUSIONS

One-week low-dose triple therapy with OCT is highly effective as an initial therapy in eradicating H. pylori infection. The efficacy is significantly lower when given as a second line treatment in patients who have previously failed to eradicate H. pylori with bismuth-based standard triple therapy.

Lithogenicity of human bile is reduced by freezing and thawing

We examined the effects of freezing and thawing upon the nucleation time and the distribution of cholesterol between micelles and vesicles in 9 human gallbladder and 7 hepatic biles. The nucleation time was significantly longer after freezing when compared to fresh samples (22.4 +/- 2.6 vs. 7.4 +/- 1.9 days, respectively). Concomitantly, a substantial shift of cholesterol from vesicles to micelles was noted, with the proportion of vesicular cholesterol decreasing from 26.5% +/- 6.0% in fresh biles to 8.6% +/- 2.3% after freezing. These effects were observed in all types of human biles, regardless of origin, cholesterol saturation or initial presence of cholesterol crystals, and were most notable after the first week of freezing. The decrease in vesicular cholesterol in all biles and the increase in nucleation time of gallbladder biles correlated with the time the samples had been in a frozen state. It is concluded that the lithogenic properties of human bile are not maintained during storage at -20 degrees C. Freezing results in a shift of cholesterol from vesicles to micelles and reduces the tendency of cholesterol to crystallize from bile samples.

The effects of dietary phospholipids enriched with phosphatidylethanolamine on bile and red cell membrane lipids in humans

The role of phospholipids in biliary cholesterol solubilization and crystallization has only recently begun to be appreciated. Phospholipid vesicles are believed to be the metastable carrier from which cholesterol nucleates. Cholesterol crystallization is influenced by the phospholipid species in bile. Feeding rats and hamsters with diets enriched in phospholipids or their precursors, especially ethanolamine, resulted in reduced cholesterol saturation of bile. Although whole phospholipids are normal dietary constituents, the effects and safety of phospholipid components have not been tested in humans. In the present study, we have evaluated the effects of a dietary phospholipid mixture, enriched with phosphatidylethanolamine, on human bile and red blood cell membrane lipid composition. Five ambulatory volunteers having a chronic indwelling T-tube, with an intact enterohepatic circulation, were investigated. Thirty-six grams of phospholipids (54% phosphatidylethanolamine, 54% linoleyl acyl chains) were added to their daily diet for fourteen days. Biliary nucleation time, cholesterol carriers, as well as plasma, red blood cell membrane, and bile lipid compositions, were monitored. Following phospholipid supplementation, the proportion of linoleyl chains (18:2) in biliary phospholipids increased significantly from 31.1 +/- 1.2 to 37.7 +/- 5.3%, while that of oleyl chains (18:1) decreased from 11.4 +/- 1.6 to 9.6 +/- 1.1%. These changes were accompanied by an increase of linoleate and its metabolite, arachidonate, in red cell membranes. Phospholipid feeding did not cause any side effects, and no significant changes in biliary nucleation time, cholesterol, phospholipid, or bile salt concentrations, or in the distribution of cholesterol within micelles or vesicles. We conclude that phospholipid feeding is safe, and can be effective as a vehicle for lecithin fatty acyl chain modulation of bile and lipid membranes. These findings may provide a basis for a controlled modulation of biliary phospholipids to increase cholesterol solubility in bile.

High Helicobacter pylori numbers are associated with low eradication rate after triple therapy

This study tested the influence of pretreatment bacterial density on the eradication rate of Helicobacter pylori with triple therapy. One hundred and thirty two patients with endoscopically confirmed H pylori positive, duodenal ulcer or antral gastritis were treated with triple therapy (colloidal bismuth/metronidazole/amoxicillin) for two weeks. Pretreatment urease activity was assessed by the 14C-urea breath test (UBT) in all patients. The mean (SD) pretreatment UBT concentration was similar in patients with duodenal ulcers (318.4 (175.0)) and patients with antral gastritis (288.9 (165.5)). Overall eradication of H pylori was achieved in 85 of 132 patients (64.4%), but was significantly different between patients with high, intermediate, or low pretreatment urease activity (37.5%, 69.5%, and 87.8% respectively). The mean post-treatment UBT value of patients in whom eradication failed was in direct correlation with the pretreatment UBT values. In conclusion, bacterial density, as assessed by urease activity, is an important factor in predicting H pylori eradication. It is suggested that the pretreatment UBT has the potential to identify patients who require modification of the standard therapeutic regimen.

Increased serum iron and iron saturation without liver iron accumulation distinguish chronic hepatitis C from other chronic liver diseases

One hundred twenty-three patients with chronic liver diseases of various etiologies were evaluated for their iron status. The patients were divided into four distinct groups: chronic hepatitis C (63), chronic hepatitis B (14), B + C (3) and nonviral chronic liver diseases (43). In 107 patients (87%) the chronic liver disease was confirmed by biopsy. Mean serum iron (+/- SD) levels in the above four groups were: 166 +/- 62, 103 +/- 52, 142 +/- 48, and 115 micrograms/dl; iron-binding capacity was 346 +/- 80, 325 +/- 72, 297 +/- 27, and 374 +/- 75 micrograms/dl, and iron saturation 50 +/- 18, 32 +/- 16, 48 +/- 16, and 28 +/- 10%, respectively. Serum ferritin, increased in all four groups, was highest in HCV; however, no evidence of hepatic iron accumulation could be found in any of the patients. There were no significant differences in liver function parameters measured in the four groups. We conclude that serum iron, iron saturation, and ferritin are increased in patients with hepatitis C in comparison to hepatitis B or other nonviral, nonhemochromatotic liver diseases. The increased iron status in hepatitis C patients is not manifested by increased liver iron. Awareness of these distinct features of chronic hepatitis C is essential in the diagnosis and treatment of chronic liver diseases.

Seasonal variation in the frequency of Helicobacter pylori infection: a possible cause of the seasonal occurrence of peptic ulcer disease

OBJECTIVES

The seasonal variation of duodenal ulcer disease and its complications have been repeatedly demonstrated in Israel by several independent studies. The aim of this study was to determine possible seasonal variations in the occurrence of H. pylori infection among dyspeptic patients in Israel.

METHODS

All 14C-urea breath tests performed in dyspeptic patients at the gastroenterology department in the Tel Aviv Medical Center from January 1991 to December 1992 were reviewed. The monthly variation in the proportion of patients with H. pylori infection was determined, and compared with that of an unrelated 14C-cholyl-glycine breath test.

RESULTS

Altogether, 702 patients were examined, and 371 (52.8%) of them were found to be infected with H. pylori. During summer months (July-September), a significant decrease in the percentage of patients infected with H. pylori was found, compared with winter months (December-January, 42.3% vs. 60.9%, p < 0.007). No seasonal variation was found in the results of 14C-cholyl-glycine test. The fluctuations in H. pylori infection were highly correlated with the seasonal occurrence of peptic ulcer disease in Israel.

CONCLUSIONS

The frequency of H. pylori infection in dyspeptic patients in Israel is significantly increased during the winter months and decreased in the summer. This seasonal variation is identical to that found in duodenal ulcer disease. Thus, the seasonal variation of peptic ulcer disease could be explained by H. pylori infection, as seen in other communicable infectious diseases.

Direct visualization of lipid aggregates in native human bile by light- and cryo-transmission electron-microscopy

The evolution of microstructures present in human gallbladder and hepatic bile was observed simultaneously by video-enhanced light microscopy (VELM) and transmission electron microscopy of vitrified specimens (cryo-TEM), as a function of time after withdrawal from patients. Fresh centrifuged gallbladder bile samples contained small (6 nm) spherical micelles in coexistence with vesicles (40 nm). Out of the seven bile samples investigated four contained, in addition, two types of elongated aggregates that have not been previously described. Uncentrifuged gallbladder bile also contained a mixture of ribbon- and plate-like crystals seen by VELM, but not by cryo-TEM. In aged (3-6-week-old) gallbladder bile samples VELM also revealed spiral and helical crystal structures. No such crystals were present in hepatic bile samples, although microcrystals, not observable by VELM were seen by cryo-TEM in addition to micelles and vesicles. The similarity of these observations to those observed in bile models lends strong support for the validity of the model systems. Furthermore, the presence of microcrystals in hepatic bile samples, apparently devoid of crystals by light microscopy, indicates that under certain conditions the common criterion of 'nucleation time' (NT), based on light microscopy, does not represent the real time of nucleation. In the human bile samples investigated in this study the dissociation between NT and the time of observation of microcrystals was seen in hepatic but not in gallbladder bile samples. Hence, crystal growth may be rate limiting only in dilute biles.

Phospholipid molecular species influence crystal habits and transition sequences of metastable intermediates during cholesterol crystallization from bile salt-rich model bile

Despite its importance in cholesterol gallstone formation, crystallization of cholesterol from bile is poorly understood, especially with respect to the influences of other biliary lipids. We reported recently (Konikoff et al. J. Clin. Invest. 1992. 90: 1155-1160) that cholesterol can crystallize from model and native biles as filamentous crystals covered by a surface layer of lecithin molecules. During growth, filamentous crystals transformed via metastable intermediates into classical plate-like cholesterol monohydrate crystals. Using the same dilute (1.2 g/dl total lipid) bile salt-rich (97.5 moles %) model bile supersaturated with cholesterol, we have studied the effects of natural egg yolk, soy bean as well as single molecular species of lecithins, other phospholipids and related lipid classes on early filamentous cholesterol crystallization, as well as transformations between crystal habits and their growth to equilibrium cholesterol monohydrate plates. After extraction and derivatization, HPLC analysis revealed that the surfaces of filamentous crystals were enriched preferentially with lecithin molecular species having longer and more saturated sn-1 and sn-2 acyl chains compared to mixed lecithin species of whole bile. In contrast, the molecular species distribution of lecithins on equilibrium plate-like crystals resembled that of whole bile. After incubation of pre-formed anhydrous cholesterol and cholesterol monohydrate crystals in cholesterol-free lipid solutions, we demonstrated that surface-adsorbed lecithins were not preferentially enriched excluding nonspecific lecithin adsorption. Time-sequences and transformations between metastable crystalline intermediates were altered markedly by specific phospholipid species: model biles composed of saturated short-chain, medium-chain, and polyunsaturated long-chain lecithins induced rapid precipitation of short filamentous crystals that became plate-like slowly by an "arborization pattern." Long-chain saturated lecithins and natural sphingomyelins retarded cholesterol crystallization markedly, and filamentous as well as metastable intermediate crystals made transient appearances only after plate-like crystals had formed. These observations suggest that phospholipid molecular species and class influence the earliest events in cholesterol crystallization from bile salt-rich model bile. Furthermore, as the molecular species of lecithins adsorbed onto filamentous cholesterol crystals were more saturated than in whole bile and essentially identical to those in biliary vesicles, this finding provides chemical evidence for a vesicular origin of the critical cholesterol nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Elastic free energy of anisotropic helical ribbons as metastable intermediates in the crystallization of cholesterol

We report measurements of the geometrical structure and temporal evolution of metastable helical intermediates in the pathway for cholesterol crystallization in native and model biles. We find that the lecithin component in the bile can dramatically affect the kinetics along this pathway. We also present a theoretical description of these helical intermediates using an elastic free energy appropriate for anisotropic bilayers of tilted chiral amphiphiles, which provides a quantitative description of the observed helical ribbon geometry and insight into the relative free energies of the observed metastable intermediates.

Filamentous, helical, and tubular microstructures during cholesterol crystallization from bile. Evidence that cholesterol does not nucleate classic monohydrate plates

Precipitation of cholesterol in gallbladder bile is believed to produce platelike cholesterol monohydrate crystals directly. We report complementary time-lapse microscopic studies of cholesterol crystallization from model bile that reveal initial assembly of filamentous cholesterol crystals covered by a monomolecular layer of lecithin. Over a few days, the filaments evolved through needle, helical, and tubular microstructures to form classical platelike cholesterol monohydrate crystals. Similar crystallization phenomena were observed in human gallbladder biles from cholesterol but not pigment stone patients. Synchrotron x-ray diffraction of the earliest filaments suggested a cholesterol monohydrate polymorph or admixture with an anhydrous cholesterol precursor. However, density gradient centrifugation of filamentous crystals revealed that their density was 1.032 g/ml, consistent with anhydrous cholesterol. Conventional x-ray diffraction of transitional crystalline forms was consistent with pure cholesterol monohydrate crystals, as were the equilibrium platelike crystals. These novel findings suggest that crystalline cholesterol in bile may not be completely mature or hydrated initially, but undergoes a series of transformations to become thermodynamically stable monohydrate plates. These observations have important implications for understanding the control of cholesterol crystallization in bile, as well as explaining putative crystal cytotoxicity during gallstone formation.