The effect of a progestin on gallbladder function in young women

Investigating gastrointestinal disorders in pregnancy

This article reviews anatomical and physiological changes and alterations in reference intervals for laboratory tests in healthy pregnancy, pertinent to investigation of the gastrointestinal system. The safety of procedures and radiological investigations relevant to the investigation of gastrointestinal disorders in pregnancy are also reviewed.

Association between the use of hormonal contraceptives and risk of cholecystectomy in women of reproductive age

PURPOSE

Previous studies have indicated an increased risk of gallbladder disease with hormonal contraceptives although with discordant results. The potential increased risk of gallbladder disease with hormonal contraceptives is concerning given that women are at increased risk of this disease. Thus, the aim of this study was to examine risk of surgery-confirmed gallbladder disease (cholecystectomy) with oral contraceptives, intrauterine devices, and injectable hormonal contraceptives.

METHODS

We conducted a retrospective cohort study. Females aged 15-45 who initiated hormonal contraceptive use were identified in the United States IQVIA Ambulatory electronic medical record database between 2008 and 2018. Cox proportional hazards models were used to estimate adjusted hazards ratios and 95% confidence intervals for cholecystectomy with eight formulations of contraceptives compared with levonorgestrel and ethinyl estradiol combined oral contraceptive. Sensitivity analysis was conducted by lagging exposure by 90 days and by excluding patients with history of gallbladder disease. Secondary analyses were conducted by cumulative duration of use.

RESULTS

We identified 1,425,821 females who initiated the use of hormonal contraceptives and generated 4417 cholecystectomy events. Overall, the use of medroxyprogesterone acetate (HR: 1.22, 95% CI: 1.07-1.40) and at least 1 year of levonorgestrel intrauterine device use (HR: 1.74: 95% CI: 1.19-2.54) were associated with increased risk of cholecystectomy when compared with levonorgestrel and ethinyl estradiol combined oral contraceptive. However, we did not observe an increased risk with other hormonal contraceptives. Consistent results were observed across sensitivity analyses.

CONCLUSION

In this large population-based study, there was an increased risk of cholecystectomy with medroxyprogesterone acetate and intrauterine device but not other hormonal contraceptives. Additional large observational studies are required to corroborate these findings.

The Hepatobiliary System: An Overview of Normal Function and Diagnostic Testing in Pregnancy

Pregnancy is associated with physiological adaptions that affect every organ system. Changes in liver function in pregnancy have important effects on nutrient metabolism, protein synthesis, and the biotransformation of substances in preparation for excretion. A clear understanding of the anatomic and functional changes of the hepatobiliary system is necessary for the diagnosis and evaluation of disease, as well as understanding how these changes predispose women to pregnancy-specific hepatic conditions. In this review, the effect of gestational changes in hepatobiliary function on laboratory tests and the role of diagnostic imaging of the liver and gallbladder in pregnancy will be discussed.

Effects of liraglutide on gallbladder emptying: A randomized, placebo-controlled trial in adults with overweight or obesity

AIMS

Treatment with liraglutide 3.0 mg has been associated with gallbladder-related adverse events. To conduct a single-centre, double-blind, 12-week trial comparing the effect of 0.6 mg liraglutide and steady-state liraglutide 3.0 mg with placebo on gallbladder emptying in adults with body mass index (BMI) ≥27 kg/m² and without diabetes.

METHODS

Participants were randomized 1:1 to once-daily subcutaneous liraglutide (n = 26) or placebo (n = 26), starting at 0.6 mg with 0.6-mg weekly increments to 3.0 mg, with nutritional and physical activity counselling. A 600-kcal (23.7 g fat) liquid meal test was performed at baseline, after the first dose and after 12 weeks. The primary endpoint was the 12-week maximum postprandial gallbladder ejection fraction (GBEF_max ), measured over 240 minutes after starting the meal.

RESULTS

Baseline characteristics were similar between groups (mean ± SD overall age 47.6 ± 10.0 years, BMI 32.6 ±3.4 kg/m² , 50% women). Mean 12-week GBEF_max (treatment difference -3.7%, 95% confidence interval [CI] -13.1, 5.7) and area under the GBEF curve in the first 60 minutes (-390% × min, 95% CI -919, 140) did not differ for liraglutide 3.0 mg (n = 23) vs placebo (n = 24). The median (range) time to GBEF_max was 151 (11-240) minutes with liraglutide 3.0 mg and 77 (22-212) minutes with placebo. Similar findings were noted after the first 0.6-mg liraglutide dose. Gastrointestinal disorders, notably nausea and constipation, were the most frequently reported adverse events.

CONCLUSIONS

Treatment with liraglutide did not affect the GBEF_max but appeared to prolong the time to GBEF_max .

Postmenopausal estrogen therapy and risk of gallstone disease: a population-based case-control study

BACKGROUND

Female gender and increasing age are key risk factors for gallstone disease; therefore, postmenopausal women are at high risk. Estrogen increases cholesterol saturation of bile and may further increase gallstone risk, but population-based evidence is sparse.

OBJECTIVE

Our objective was to examine the association between postmenopausal estrogen therapy and risk of gallstone disease and the impact of duration of treatment and use of opposing progestin.

STUDY DESIGN

We conducted a population-based case-control study. Cases were postmenopausal women (defined as aged ≥45 years) with gallstone disease identified in the period 1996-2010. For each case, we selected ten population controls matched to cases by age and sex. We defined exposure as any use of estrogen (opposed and unopposed by progestin). Cases/controls were categorized as current estrogen users if their last prescription was redeemed <90 days before gallstone diagnosis (or corresponding date for controls); all other users were categorized as former users. The reference group consisted of cases/controls with no/rare estrogen use.

SETTING

Medical databases covering the population of Northern Denmark (2.4 million inhabitants through the period 1996-2010).

MAIN OUTCOME MEASURE

We used conditional logistic regression to compute adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) of gallstone disease in women treated with estrogen. The ORs were adjusted for relevant comorbidity, other drugs known to influence gallstone risk, and parity.

RESULTS

We identified 16,386 cases with gallstone disease and 163,860 controls. A total of 1,425 cases (8.7 %) and 8,930 controls (5.4 %) were current estrogen users, yielding an adjusted OR for gallstone disease of 1.74 (95 % CI 1.64-1.85) compared with non-users. The corresponding adjusted OR for former users was 1.35 (95 % CI 1.28-1.42). The results suggested a duration response for current users. Use of unopposed estrogen was associated with higher adjusted ORs than estrogen opposed by progestin.

CONCLUSION

Postmenopausal estrogen therapy was associated with increased risk of gallstone disease in current and former estrogen users. Use of unopposed estrogen was associated with higher risk than use of estrogen opposed by progestin; this finding needs to be confirmed and explored further in future studies.

Is there a link between oestrogen therapy and gallbladder disease?

Cholelithiasis is the most common form of benign gallbladder disease that results in major heath expenditure. Female sex hormones are causally related to cholesterol gallstone disease, which are more common in women than in men. The risk of development of cholelithiasis is further enhanced by the use of exogenous female sex hormones and by pregnancy. Oestrogens are used in oral contraceptives and in hormone replacement therapy (HRT). Oral contraceptives do not pose a greater risk for gallbladder disease. The findings from two randomised, controlled trials, the Heart and Oestrogen/Progestin Replacement Study and the Women's Health Initiative postmenopausal hormone trial, unequivocally confirm that oral oestrogen use in postmenopausal women is causally associated with gallbladder disease, and the magnitude of the effect is not influenced greatly by the presence or absence of progestins. A cautious approach should be observed when prescribing HRT. Women must be informed about the effect of oestrogen use on increased risk of benign gallbladder disease. HRT should be used in the lowest possible dose for the shortest possible time. Women harbouring asymptomatic gallstones should not receive oestrogens because of the possibility of developing cholecystitis.

Controversies concerning pathophysiology and management of acalculous biliary-type abdominal pain

Acalculous biliary-type abdominal pain is a commonly encountered clinical problem whose pathophysiology is unclear and evaluation and management are controversial. Cholecystokinin cholescintigraphy to measure the gallbladder ejection fraction (GEF) has been advocated as a criterion for cholecystectomy. However, there is no consensus regarding the dose and rate of infusion of cholecystokinin, both of which can alter the GEF, and the definition of an abnormal ejection fraction varies among studies. Many but not all studies have concluded that a low GEF predicts good outcomes after cholecystectomy, but most studies suffer from poor methodology and there is only one prospective randomized controlled trial. Also, some patients with a normal GEF have responded to cholecystectomy. Another controversial area has been the role of sphincter of Oddi dysfunction (SOD) in patients with biliary-type pain and gallbladder in situ. Some reports suggest an overlap between SOD and low GEF, although a causal relationship has not been established. Yet another subject of interest is the role of visceral hyperalgesia in patients with acalculous biliary-type pain. We have reviewed the relevant literature relating to these issues and have highlighted the controversial aspects. In the absence of high-quality studies, an evidence-based treatment algorithm is difficult to design but will be proposed. More prospective controlled trials are warranted to better define the appropriate evaluation and management of patients with this syndrome.

Functional biliary-type pain: update and controversies

Recurrent biliary-type abdominal pain is a perplexing clinical dilemma that occurs in patients with an acalculous gallbladder in situ or in patients who have undergone a previous cholecystectomy. The pathogenesis of functional biliary-type pain is often unclear; therefore, evaluation and management remain controversial. In patients with an acalculous gallbladder in situ, critical importance has been given to delayed gallbladder emptying using cholescintigraphy (CCK-CS) to determine if gallbladder dysfunction is present. However, several issues remain unresolved, including methodology, definition of delayed emptying, and the absence of high-quality studies to determine if CCK-CS can predict who will do well with cholecystectomy. In patients with previous cholecystectomy, the main area of controversy is the evaluation of patients with sphincter of Oddi Type III, including the role of endoscopic retrograde cholangiopancreatography with SO manometry and sphincterotomy in these patients. Suggested algorithms for management of both clinical scenarios are provided.

Intracellular liposomes and cholesterol deposits in chronic cholecystitis and biliary sludge

Ultrastructural study of a group of selected specimens of chronic cholecystitic gallbladders reveals cholecystocyte changes characterized by abraded and altered microvilli accompanied by mitochondrial damages in the apical regions as well as mucus accumulation with aggregated, angulated lysosomes and heterogeneous liposomes. These liposomes contain needle-like crystals, probably rich in cholesterol. Many fragments of cholecystocystes and damaged organelles or contents can be found in the biliary sludge. These data support previous reports suggesting that there is an association between cholecystitis and the presence of cholelithiasis, subsequent to the production of altered bile. The present data suggest that disintegrating, sloughed cholecystocyte contents also contribute to the bile sludge, a complex milieu enriched by lipids, cholesterol deposits, altered mucus due in part to changes in expression of apomucins. The instability of prolonged storage of such modified bile, caused and/or accompanied by other associated metabolic defects, including gallbladder sluggishness, would favor the nucleation and the enlargement of gallstones. Based on the aforementioned data, a comprehensive sequence for cholecystocyte ultrastructural alterations and pathologies is proposed, as a result of chronic cholecystitis.

Compounded Versus Proprietary Sincalide for Evaluation of Gallbladder Ejection Fraction

OBJECTIVE

To report a comparison of compounded and proprietary sincalide in the evaluation of gallbladder ejection fraction during hepatobiliary scintigraphy.

CASE SUMMARIES

Two patients were referred to nuclear medicine with symptoms consistent with hepatobiliary dysfunction. Both underwent hepatobiliary scintigraphy to evaluate anatomic and physiologic tract patency of the hepatobiliary system. Compounded sincalide, an adjuvant pharmaceutical used to evaluate gallbladder ejection fraction, was infused during hepatobiliary scintigraphy, and gallbladder ejection fractions were 11% and 24%, respectively. Hepatobiliary scintigraphy was repeated on both patients 72 hours later with proprietary sincalide used as the adjuvant pharmaceutical. The gallbladder ejection fractions were 32% and 72%, respectively.

DISCUSSION

The use of sincalide to evaluate gallbladder ejection fraction in hepatobiliary scintigraphy is widely accepted in the surgical and nuclear medicine community. In late 2001, the sole manufacturer of sincalide announced indefinite unavailability of the product. Following the announcement, several compounding pharmacies began selling extemporaneously compounded sincalide as a replacement. Use of the compounded product has assumed therapeutic equivalence.

CONCLUSION

Significant differences in gallbladder ejection fraction between compounded sincalide and sincalide in our patients are likely due to the intrinsic variability in response to sincalide. Clinicians should be aware of this variability, as well as the potential effect of concomitant medications.

Incidence of gallstones in chronic renal failure patients undergoing hemodialysis: experience of a center in Turkey

OBJECTIVE

In this case-control study, we sought to determine whether the incidence of gallbladder stones (GBS) was increased in chronic renal failure (CRF) patients on a hemodialysis (HD) program. We also evaluated factors, such as lipid profiles and gallbladder motility, that could affect the formation of GBS. In addition, we reviewed other available studies on this subject and compared the factors that might have some influence on the development of GBS.

METHODS

A total of 182 CRF patients (135 male, 47 female, mean age 32.1 yr) undergoing chronic HD and who were referred to our transplantation center in the last 10 yr and 194 healthy controls (137 male, 57 female, mean age 33.3 yr) were included in the study. Abdominal ultrasound was performed on all patients, and ALT, AST, and lipid profiles were determined. In addition, 19 patients with CRF (12 male, 7 female, mean age 33.5 yr) and 22 controls (14 male, 8 female, mean age 33.2 yr) who were age and sex matched were randomly chosen for gallbladder emptying, monitored by ultrasound at 30-min intervals for 2 h after a mixed meal. Fasting volume, minimal residual volume, and ejection fraction of the gallbladder were assessed. For statistical analysis, chi(2), t test, and logistic regression analysis were used.

RESULTS

GBS were detected in seven patients with CRF (3.85%, 5 male, 2 female) and three controls (1.55%, one male, two female) (p > 0.05). The mean follow-up time of CRF patients after diagnosis was 39.3 months (range: 2-168), the mean duration of HD was 21.8 months (range: 1-120). The analysis of seven stones in the CRF group revealed that five were cholesterol-rich stones, and two were mixed (cholesterol and bilirubin) stones. Cholesterol levels were higher in the control group, and triglycerides were higher in the CRF group, but these findings were nonsignificant (p > 0.05). Other biochemical values were not significantly different between the groups. CRF patients with and without GBS were similar in their duration of CRF and HD, age, and other biochemical parameters (p > 0.05). When gallbladder emptying was considered, there was no difference between the two groups in fasting volume, residual volume, and ejection fraction (CRF: 89.7%; controls: 92.3%) of the gallbladders (p > 0.05).

CONCLUSIONS

We detected similar incidences of GBS in CRF patients undergoing HD and healthy controls, and this was comparable to the results of most of the previous studies. Young male CRF patients had a nonsignificantly higher incidence of GBS than control males. Although cholesterol-rich GBS were predominant, we could not find any significant difference between the groups when factors that could affect GBS formation, such as lipid profiles and gallbladder motility, were taken into account.

Ultrasonographic assessment of gallbladder bile exchanges in healthy subjects and in gallstone patients

Impaired gallbladder motility may contribute to gallstone pathogenesis by providing time for nucleation and aggregation of cholesterol crystals. Simultaneous scintigraphic-ultrasonographic techniques have been proposed to assess alternating phases of gallbladder emptying and filling. To evaluate patterns of gallbladder motility and of postprandial bile flow by means of a single ultrasonographic technique, 12 healthy volunteers and 20 gallstone patients underwent minute-by-minute gallbladder ultrasonography for 3 h postprandially. Mathematical analysis of volume measurements was used to estimate hepatic and cholecystic bile flux through the gallbladder. Compared to controls, gallstone patients showed greater amounts of unexchanged cholecystic-to-hepatic bile (11% vs. 1%, p <.001) and most of them showed impaired gallbladder washout efficacy. Utrasonographic values of bile exchanges were similar to those derived from scintigraphic-sonographic studies in comparable groups of subjects. This study provides new ultrasonographic variables, which better express gallbladder bile retention in gallstone patients and strongly discriminate gallstone patients from controls.

Progesterone alters biliary flow dynamics

OBJECTIVE

To test the hypothesis that progesterone alters sphincter of Oddi and gallbladder function and, therefore, bile flow dynamics.

SUMMARY BACKGROUND DATA

Although the effects of progesterone on the biliary tract have been implicated in the increased incidence of gallstones among women, the specific effects of prolonged elevation of progesterone levels, such as occurs with contraceptive progesterone implants and during pregnancy, on the sphincter of Oddi and biliary flow dynamics are still incompletely understood.

METHODS

Adult female prairie dogs were randomly assigned to receive subcutaneous implants containing either progesterone or inactive pellet matrix only. Hepatic bile partitioning and gallbladder emptying were determined 14 days later using 99mTc-Mebrofenin cholescintigraphy.

RESULTS

Significantly less hepatic bile partitioned into the gallbladder in progesterone-treated than in control animals. The gallbladder ejection fraction was significantly reduced from 73+/-6% in controls to 59+/-3% in the progesterone-treated animals. The rate of gallbladder emptying was significantly reduced from 3.6+/-0.3%/minute to 2.9+/-0.1%/minute.

CONCLUSIONS

Progesterone administered as subcutaneous implants alters partitioning of hepatic bile between gallbladder and small intestine and, therefore, gallbladder filling. Progesterone also significantly impairs gallbladder emptying in response to cholecystokinin. The effects of progesterone on the sphincter of Oddi and the gallbladder may contribute to the greater prevalence of gallstones and biliary motility disorders among women.

The basis for progesterone impairment of gallbladder contractility in male guinea pigs in vitro

Progesterone suppresses gallbladder smooth muscle function but its exact mechanism is unknown. We sought to determine the cellular site where progesterone impairs gallbladder smooth muscle. Sixty-four adult male guinea pigs were injected with either progesterone (2 mg/kg/day sc) or normal saline (controls) for 7 days. Dose-response curves of gallbladder strips to cholecystokinin (CCK), bethanechol, and potassium (K+) were constructed in vitro. To better define the basis for the progesterone effect, gallbladder contractile response was determined to specific agonists: aluminum fluoride and mastoparan (direct G-protein activators), cyclopiazonic acid (CPA), and a calcium ionophore (A-23187). Gallbladder from animals on progesterone exhibited a marked decrease in contractile response to CCK and bethanechol compared with controls (P < 0.05). Further, gallbladder contraction remained depressed (P < 0.05) in progesterone-treated animals, when the G protein was directly activated with aluminum fluoride and mastoparan. In contrast, the responses to K+ (acting independent of receptor G-protein) and to A-23187 and CPA (agonists that bypassed the membrane) were comparable in both groups (NS). It is concluded that progesterone directly inhibits gallbladder smooth muscle contractility in vitro to a standard hormone, CCK, and a cholinergic agent. Such depressed contraction is not due to an altered contractile machinery, since it is normal with agonists that act independently of G-protein activation. Progesterone thus interferes with signaling through the G-protein, either by directly becoming closely associated with the cell membrane or by indirectly perturbing its receptor products.

Cholelithiasis induced in the Syrian hamster: evidence for an intramucinous nucleating process and down regulation of cholesterol 7 alpha-hydroxylase (CYP7) gene by medroxyprogesterone

This report reviews previously published studies from our laboratory and shows some recent morphological data obtained with scanning and transmission electron microscopy regarding gallstone formation and alteration of the gallbladder epithelium in the Syrian hamster model. Both male and female hamsters were treated with female sex steroids (estradiol alone, estradiol and medroxyprogesterone, medroxyprogesterone alone) during one month. The results show that the Syrian hamster is a good model to study bile changes, gallbladder structure changes, including gallstone formation, and the regulation of cholesterol metabolism at the molecular level. Arguments in favor of this animal model are presented and, during gallstone formation, epithelial cell changes, anionic mucus secretion, and formation of gallbladder luminal deposits can be demonstrated. Recent molecular biology observations related to the effect of female sex steroids on liver cholesterol 7 alpha-hydroxylase (CYP7) gene suggest that progestin alone or primed by estrogen down regulates CYP7 transcription and activity. In addition, progesterone in cell culture systems has been shown to enhance intracellular accumulation of free cholesterol by increasing its uptake and synthesis and by decreasing its esterification by inhibiting the activity of acylcoenzyme A: cholesterol acyltransferase. Non-esterified cholesterol is free to migrate to the extracellular spaces and may contribute to nucleation within the bile. It is suggested that these effects of progesterone on cholesterol metabolism combined with the CYP7 gene down regulation, physical changes in the mucus and the hypomotility of the gallbladder and biliary ducts result in hypersaturation of cholesterol in the bile which favors gallstone formation.

Ultrastructural aspects of human gallbladder epithelial cells in cholelithiasis: production of anionic mucus

The surface epithelium of 28 gallbladders removed during elective cholecystectomies and pathology collection was studied ultrastructurally. Focusing on 10 of the 28 cases that were diagnosed as cholecystitis, we found that the epithelium displayed numerous apical mucous granules and bulging apical apices. Mucous granule changes included 1) hyperproduction of secretory granules of neutral type containing an electron-dense proteinaceous spherule, similar to that described in other mucus-producing glands of the digestive system, and 2) production of anionic, osmiophilic secretory mucus. Other alterations of the surface epithelial cells included the production of bizarre surface appendages resembling primitive cilia without axoneme and epithelial excrescences.

Postprandial gallbladder motor function: refilling and turnover of bile in health and in cholelithiasis

BACKGROUND & AIMS

Impaired gallbladder emptying is implicated in gallstone disease. Ultrasonography and scintigraphy have shown conflicting results because the former is influenced by postprandial refilling, whereas the latter is not influenced by refilling. The aim of this study was to measure postprandial refilling and turnover of bile by combining the two techniques.

METHODS

Simultaneous scintigraphy and ultrasonography were used in 14 patients with gallstones and 11 healthy controls. Measurements were performed while the patients were fasting and at 10-minute intervals after a standard meal for 90 minutes, and the measurements were used to calculate postprandial refilling, turnover of bile (in milliliters), and turnover index.

RESULTS

Ultrasonography and scintigraphy provided different gallbladder emptying patterns. Compared with controls, patients with gallstones had impaired emptying by both scintigraphy (P < 0.0001) and ultrasonography (P < 0.01). Postprandial refilling and turnover were both reduced between 60 and 90 minutes (P < 0.05), and the turnover index was markedly reduced (1.8 vs. 3.5; P < 0.001).

CONCLUSIONS

Simultaneous scintigraphy and ultrasonography provide a new model of gallbladder motor function showing that refilling begins immediately postprandially. In healthy controls, the gallbladder postprandially handles up to six times its basal volume within a period of 90 minutes, but this turnover of bile is markedly reduced in cholelithiasis causing a reduced washout effect of the gallbladder contents, including cholesterol crystals.

Oral contraceptive use and benign gallbladder disease; revisited

An analysis is described of 482 women with benign gallbladder disease (surgically confirmed in 407) identified in the Oxford Family Planning Association contraceptive study. There was no significant overall association between oral contraceptive use and gallbladder disease (relative risk ever use to never use 1.1, 95% confidence interval 0.9 to 1.3). Likewise, duration of oral contraceptive use had no significant effect (relative risk 97 or more months use to never use 1.1, 95% confidence interval 0.8 to 1.5). There was no indication of any interaction between oral contraceptive use and body mass index or oral contraceptive use and age in the production of disease. It is concluded that it is unlikely that oral contraceptives are of either clinical or public health significance in relation to the occurrence of gallbladder disease.

Influence of oral contraceptives on fasting gallbladder volume

A total of 615 healthy fertile women (518 pill users and 97 non-users) were examined by real-time ultrasonography for fasting gallbladder volume, gallstones and biliary dysmorphism. None of the six examined combinations of oral contraceptives appeared to influence fasting gallbladder volume significantly. When fasting gallbladder volumes were reanalyzed according to the presence or absence of recognized biliary risk factors, significant modifications were detected, in both pill users and non-users. These changes related only to age and parity. Relative risks of cholelithiasis and biliary dysmorphism were not affected by contraceptive treatment.

Apical excrescences in the gallbladder epithelium of the female Syrian hamster in response to medroxyprogesterone

All the intact female Syrian hamsters treated with medroxyprogesterone (MP) for a one-month period, without dietary manipulation, display gallbladder surface epithelial changes, and intraluminal deposits. These changes include excrescences in various stages, bulging, and extrusion of material from the epithelial cells. The most striking scanning electron microscopic observations are the dramatic events, comparable to apocrine-like secretory events observed in another related study using oophorectomized hamsters. Since the hamster gallbladder does not possess mucous goblet cells, it appears that this phenomenon could be a response to the MP treatment, thus providing a larger amount of mucous product than usual with cellular material, in addition to the possible alteration in the quality of the bile following this treatment. As a result of MP treatment, intraluminal deposits were also confirmed by using light and transmission electron microscopy. In control hamsters these events were not observed, however, small blebs outlining surface epithelial cells are seen. The results in this report complement the previous studies using the male and oophorectomized Syrian hamster model subjected to similar experimental conditions.

Plasma concentrations of motilin and somatostatin are increased in late pregnancy and postpartum

OBJECTIVE

To examine plasma levels of motilin and somatostatin throughout pregnancy.

DESIGN

Prospective observational study.

SETTING

University Hospital, Norway.

SUBJECTS

Eight healthy pregnant women (aged 24-38 years) six of them primigravidae and eight healthy non-pregnant women of similar age with ovulatory menstrual cycles.

INTERVENTIONS

In the pregnant women blood samples were obtained at 4-week intervals from 8 weeks gestation throughout pregnancy and again at 5 days and 28 days postpartum. In the non-pregnant controls blood samples were obtained on cycle days 4, 7, 10, 13, 14, 15, 18, 21 and 24.

MAIN OUTCOME MEASURES

Plasma levels of motilin and somatostatin.

RESULTS

Plasma concentrations of both motilin and somatostatin rose continuously during pregnancy, and motilin levels increased still further to a peak of 165.1 (SE 35.8) pmol/l at 5 days postpartum. Plasma motilin levels were significantly higher during the third trimester and at 5 days postpartum compared with non-pregnant controls (P less than 0.0001). The highest plasma somatostatin levels were found at 40 weeks gestation and at 5 days postpartum (mean 32.1 SE 1.1 pmol/l). Somatostatin levels were significantly higher during the second and third trimester and the postpartum period compared with levels in the follicular phase of the non-pregnant controls (P less than 0.0001).

CONCLUSIONS

Circulating levels of motilin cannot play a major role in the relaxation of the gut in pregnancy, but somatostatin may play a part in regulating motility.

Female sex steroid induced epithelial changes in the gallbladder of the ovariectomized Syrian hamster

Ovariectomized Syrian hamsters treated by female sex steroids during a 1-month period show gallbladder surface epithelial changes in the fundic area consistent with apical bulging and decapitations of the epithelial cells. These events were detected in the infundibulum and the fundic or body regions of estrogen- and estrogen+progesterone-treated hamsters. In control hamsters, these events were restricted to the region in the vicinity of the bile duct. Following steroid treatment, intraluminal deposits detected resembled Ca-bilirubinate deposits described in previous studies while decapitations are similar to endometrial epithelium changes associated with hormonal physiological changes or treatments. Moreover some small electron-dense deposits are comparable to those found in human cholesterol gallstones. This report indicates that, besides an alteration in bile composition, cell fragments originating from the surface epithelium of the bile duct and/or of the gallbladder mucosal epithelium could participate in gallstone nucleation.

Gall bladder emptying patterns in response to a normal meal in healthy subjects and patients with gall stones: ultrasound study

In this study gall bladder emptying patterns in response to a solid meal were studied using ultrasound. A similar triphasic pattern was seen in eight healthy control subjects and eight patients with gall stones, with 'early' and 'late' net emptying phases separated by a period of net refilling with peak postprandial gall bladder volumes occurring at (mean (SD)) 33.1 (17.9) minutes and 27.4 (18.8) minutes in control subjects and patients, respectively. A phase of slower net emptying followed, which was complete at 146 (33) minutes in control subjects and 125 (33) minutes in the gall stone patients (not significant). Superimposed upon this overall triphasic pattern, postprandial gall bladder emptying was punctuated by repeated short lived episodes of filling and emptying. The mean (SD) estimated postprandial bile outputs were 0.83 (0.34) ml/min in four control subjects and 1.2 (1.1) ml/min in seven patients with gall stones. We propose a 'washout' model to reconcile this large turnover of bile with the concentrating and storage functions of the gall bladder and predict that the extent rather than the rate of gall bladder emptying is important in determining stasis of bile in the gall bladder.

Motor function of the gallbladder: measurement and clinical significance

Abnormalities in gallbladder emptying commonly occur in gallstone patients. Similar changes can be found in patients without gallstones that have disease that may predispose to stones, such as diabetes. Decreased contractility of the gallbladder can be measured clinically with variety of radiological techniques, and ultrasonography seems to have a number of advantages over others. In addition to a role in pathogenesis, decreased gallbladder emptying may determine the clearance of gallstones from the gallbladder during dissolution and after lithotripsy.

The association of oral contraception with kidney cancer, colon cancer, gallbladder cancer (including extrahepatic bile duct cancer) and pituitary tumours

This paper reviews the evidence for a relationship between oral contraceptive use and certain neoplasms: cancers of the kidney, colon and gallbladder (including the extrahepatic bile ducts) and tumours (benign or malignant) of the pituitary. Special reference is made to controlled epidemiological studies, both case-control and cohort. There is no convincing evidence that oral contraceptive use is causally related, either negatively or positively, to any of the tumours studied.

Augmented cholescintigraphy: its role in detecting acute and chronic disorders of the hepatobiliary tree

Cholecystagogue cholescintigraphy can be employed as a means of (1) confirming the surgeon's and/or gastroenterologist's clinical impression of symptomatic chronic acalculous biliary disease, (2) better understanding the pathophysiology of gallbladder disease, (3) preparing patients for hepatobiliary scintigraphy who have fasted for longer than 24-48 hours and who are suspected of acute cholecystitis, and (4) reducing the time required to confirm the clinical impression of acute cholecystitis. Morphine-augmented cholescintigraphy is also used to decrease the time required to determine cystic duct patency. Phenobarbital-augmented cholescintigraphy is used as a means of increasing the accuracy of hepatobiliary scintigraphy in differentiating neonatal hepatitis from biliary atresia. Nonpharmacological interventions and augmentations have been employed to maintain the high degree of accuracy of cholescintigraphy in confirming the clinical impression of acute cholecystitis. The efficacy of these modalities in detecting acute and chronic disorders of the hepatobiliary tree as well as how and why they are performed comprise the contents of this article.

Mechanisms of gallstone formation in women. Effects of exogenous estrogen (Premarin) and dietary cholesterol on hepatic lipid metabolism

Our aim was to define mechanisms whereby conjugated estrogens (Premarin, exogenous estrogen; Ayerst Laboratories, New York) increase the risk of developing cholesterol gallstones and to determine the role, if any, of dietary cholesterol. We studied gallbladder motor function, biliary lipid composition and secretion, cholesterol absorption, cholesterol synthesis and esterification by peripheral blood mononuclear cells, the clearance of chylomicron remnants, and bile acid kinetics in 29 anovulatory women. 13 were studied on both a low (443 +/- 119 mumol/d) and high (2,021 +/- 262 mumol/d) cholesterol diet. Premarin increased the lithogenic index of bile (P less than 0.05), increased biliary cholesterol secretion (P less than 0.005), lowered chenodeoxycholate (CDCA) pool (P less than 0.001) and synthesis (P less than 0.05), altered biliary bile acid composition [( CA + DCA]/CDCA increases, P less than 0.005), stimulated cholesterol esterification (P less than 0.03), and enhanced the clearance of chylomicron remnants (P = 0.07). Increases in dietary cholesterol stimulated the biliary secretion of cholesterol (P = 0.07), bile acid (P less than 0.05), phospholipid (P = 0.07), and as a result, did not alter lithogenic index. The reduction in CDCA pool and synthesis by Premarin was reversed by increasing dietary cholesterol. Off Premarin, only 24% of the increase in cholesterol entering the body in the diet was recovered as biliary cholesterol or newly synthesized bile acid. On Premarin, 68% of this increase in cholesterol was recovered as these biliary lipids. We conclude that Premarin increases biliary cholesterol by enhancing hepatic lipoprotein uptake and inhibiting bile acid synthesis. These actions of Premarin divert dietary cholesterol into bile.

Changes in postprandial release patterns of gastrointestinal hormones in late pregnancy and the early postpartum period

Intestinal transit time increases and gastrointestinal incretin effect is reported to decrease in pregnancy. The release patterns of gastrointestinal hormones related to these functions were studied in eight women before and after ingestion of a standardized meal at 32-34 weeks gestation and at 4 days postpartum. Basal plasma motilin and the integrated meal response of motilin, pancreatic polypeptide (PP) and gastric inhibitory polypeptide (GIP) were significantly lower in pregnancy than postpartum. The meal-induced rise of somatostatin and vasoactive intestinal polypeptide (VIP) was, however, absent in late pregnancy; whereas the somatostatin response recovered postpartum, and the plasma VIP concentrations stabilized at significantly higher levels postpartum without any meal response. Basal and meal-induced plasma insulin were significantly higher in pregnancy.

The effects of prosthetic gallstones on gallbladder function and bile composition

Diminished gallbladder emptying has been implicated in the pathogenesis of gallstone formation. This study assessed the effect of the physical presence of inert, prosthetic gallstones on gallbladder contractility, histopathology, and bile composition. Three glass beads, each 3 mm in diameter, were implanted in the guinea pig gallbladder. Six weeks later the in vitro contractility was assessed in response to cholecystokinin. Sham-operated animals underwent cholecystotomy without bead implantation. The gross and microscopic appearance of gallbladders from sham-operated and implanted animals was the same. The presence of stones moderately inhibited gallbladder contraction reaching 20.5% (P less than 0.05) at the maximally effective dose of cholecystokinin compared to sham-operated animals. Sham-operated and control (unoperated) animals had similar gallbladder contractility. Thus surgery itself did not alter gallbladder motility. The presence of stones had no effect on biliary lipid composition. It thus appears that gallstones, in the unobstructed gallbladder, cause only a moderate inhibition of gallbladder contractility and have little effect on biliary physiology.

Abnormal gallbladder emptying in a subgroup of patients with gallstones

Gallbladder stasis has been implicated in gallstone formation. Gallbladder filling and emptying were quantitated by computer-assisted cholescintigraphy in 41 normal subjects versus 26 patients with gallstones. Gallbladder contraction was induced by low-dose (1.2 U/kg . h) cholecystokinin infusion. Gallstone patients exhibited normal gallbladder filling, but emptying was significantly (p less than 0.01) reduced compared with controls. On closer inspection, the patients fell into two subgroups, separated by t1/2, the time to empty 50% of gallbladder contents, 19.1 min (mean + 2 SD of control). Fifteen patients (57.7%) with a normal t1/2 (less than 19.1 min) exhibited both normal filling and normal emptying. The remaining 11 patients (43.3%) with t1/2 greater than 19.1 min had grossly abnormal gallbladder emptying, significantly (p less than 0.001) different from both the previous patient subgroup and the controls. There was no significant difference in age, sex, prevalence of obesity, presence or absence of biliary colic, and gallstone size, number, or calcification between these two subgroups. Thus, defective gallbladder emptying is evident in a subgroup of gallstone patients, and is independent of clinical features, stone size, and number. Impaired emptying should be considered when assessing pathogenesis or medical therapy.