Mice lacking mitochondrial uncoupling protein are cold-sensitive but not obese

The mitochondrial uncoupling protein (UCP) in the mitochondrial inner membrane of mammalian brown adipose tissue generates heat by uncoupling oxidative phosphorylation. This process protects against cold and regulates energy balance. Manipulation of thermogenesis could be an effective strategy against obesity. Here we determine the role of UCP in the regulation of body mass by targeted inactivation of the gene encoding it. We find that UCP-deficient mice consume less oxygen after treatment with a beta3-adrenergic-receptor agonist and that they are sensitive to cold, indicating that their thermoregulation is defective. However, this deficiency caused neither hyperphagia nor obesity in mice fed on either a standard or a high-fat diet. We propose that the loss of UCP may be compensated by UCP2, a newly discovered homologue of UCP; this gene is ubiquitously expressed and is induced in the brown fat of UCP-deficient mice.

Examining the diagnostic utility of the Fuld cholinergic deficit profile on the Japanese WAIS-R

The diagnostic utility of the Fuld cholinergic deficit profile (Fuld, 1984) to dementia of the Alzheimer type (DAT) was evaluated on the Japanese version of the WAIS-R. Profiles were calculated for groups of subjects with DAT(n = 236), vascular dementia (n = 29), frontotemporal dementia (n = 22), and hydrocephalic dementia (n = 10). The frequency of positive profile occurrence for the subject groups was as follows: 23/236 for DAT (9.7%), 2/29 (6.9%) for vascular dementia, 2/22 (9.1%) for frontotemporal dementia, and 2/10 (20%) for hydrocephalic dementia. No significant difference in the frequency of positive profile occurrence was revealed across four types of dementia. We conclude from these findings that the Fuld profile lacks the diagnostic utility on the Japanese WAIS-R.

Cholestyramine loading test to assess hepatic reserve for bile acid synthesis in patients with chronic liver diseases

BACKGROUND & AIMS

Serum 7alpha-hydroxycholesterol level reflects hepatic bile acid synthesis in humans. The aim of this study was to examine the maximal bile acid synthesis in patients with chronic liver diseases.

METHODS

Cholestyramine (12 g/day) was administered for 3 days to patients with compensated liver cirrhosis (n = 7), patients with chronic hepatitis (n = 10), and control subjects (n = 9), and serum total 7alpha-hydroxycholesterol level was measured by gas-liquid chromatography-mass spectrometry.

RESULTS

A preliminary study showed that cholestyramine increased the serum value to the maximum by the third day. Before cholestyramine treatment, there were no significant differences in serum 7alpha-hydroxycholesterol levels among the groups. Three days of cholestyramine treatment increased the serum levels 5.71 +/- 2.90-fold in the controls, 3.25 +/- 0.85-fold in patients with chronic hepatitis, and 1.70 +/- 0.78-fold in cirrhotic patients. Cirrhotic patients had significantly lower serum 7alpha-hydroxycholesterol levels after the treatment compared with other groups. Serum 7alpha-hydroxycholesterol levels stimulated by cholestyramine significantly correlated with serum albumin levels and indocyanine green retention rate.

CONCLUSIONS

Three days of cholestyramine loading increased the bile acid synthesis to its maximal level. The cholestyramine test showed that patients with chronic hepatitis had enough hepatic reserve for bile acid synthesis; however, patients with compensated liver cirrhosis had significantly decreased capacity.

Effect of smoking on the prevalence of albuminuria in Japanese men with non-insulin-dependent diabetes mellitus

Smoking is a risk factor for diabetic nephropathy in patients with IDDM and potentially those with NIDDM. We investigated the relationship between renal involvement and cigarette smoking in 148 men with NIDDM. The presence of renal involvement was assessed by determining the overnight urinary albumin/creatinine ratio (mg/g, ACR). The patients were divided into three groups, normo-, micro-, and macroalbuminuria, based on the ACR (< 30, 30-300, and 300 < or = mg/g, respectively). The incidence of micro-/macroalbuminuria in 81 smokers was significantly higher than that in 21 ex-smokers (stopped smoking at least 10 years prior to the study) or 40 non-smokers (53.1, 33.3, and 20.0%, respectively). The prevalence of smoking in the groups of patients with normo-, micro-, and macroalbuminuria were 45, 73, and 76%, respectively. The relative risk (odds ratio) for the prevalence of micro-/macroalbuminuria associated with smoking was 4.5 (95% CI, 1.9-11.6, P < 0.001) in smokers and was 2.0 (not significant) in ex-smokers. Our results indicate that stricter counselling about the importance of quitting smoking will be necessary in patients with NIDDM to protect against the development of diabetic nephropathy.

Strain differences in sensitivity to the promoting effect of sodium L-ascorbate in a two-stage rat urinary bladder carcinogenesis model

Rat strain differences in sensitivity to the promoting effect of sodium L-ascorbate (SA) on the development of urinary bladder tumors were investigated. In experiment 1, WS/Shi (WS), ODS/Shiod/od (ODS), and LEW/Crj (LEW) rats were initiated with 0.05% N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) in their drinking water and subsequently given basal Oriental MF diet (M) with or without a 5% SA supplement. In LEW rats the SA treatment increased the induction of neoplastic lesions in the urinary bladder, whereas WS and ODS animals proved unresponsive to its promoting effects. In experiment 2, WS and F344 rats were maintained on two kinds of commercial basal diets, M and CLEA CA-1 (C), during administration of SA, since dietary factors can influence promoting effects. Feeding M during the promotion period in F344 rats yielded significantly more neoplastic lesions than feeding C, but in WS rats no such dietary influence was apparent. In experiment 3, strain differences in biosynthesis of alpha-2u-globulin (alpha 1a-g) were assessed because both alpha 2a-g in the urine and administration of sodium salts of organic acids such as SA have been reported to be involved in tumor promotion. Immunohistochemical analysis of renal tubules and Western blotting analysis of urine revealed the presence of alpha 2a-g in all three strains examined. These data suggest that differences in susceptibility to promotion are due to genetic factors rather than dietary factors and the ability to synthesize alpha 2a-g.

[Japanese version of the Neuropsychiatric Inventory--a scoring system for neuropsychiatric disturbance in dementia patients]

BACKGROUND AND PURPOSE

Neuropsychiatric disturbances are common and burdensome symptoms of dementias. Assessment and measurement of neuropsychiatric disturbances are indispensable to the management of patients with dementia and for clinical research. No standardized instruments have been developed for these purposes in Japan. The Neuropsychiatric Inventory (NPI), developed by Cummings et al., is a standardized, validated, and reliable tool to assess a wide range of neuropsychiatric derangements in patients with dementia, and has been used in clinical studies in North America. In this study, we prepared a Japanese version of the NPI and tested its reliability and usefulness in dementia patients.

SUBJECTS AND METHODS

The subjects were 174 patients with dementia, including Alzheimer's disease (140), frontotemporal dementia (12), vascular dementia (19), and normal pressure hydrocephalus (3), whose diagnosis was made on the basis of the results of extensive examinations including MRI and PET/SPECT of the brain and appropriate clinical diagnostic criteria for each disorder. The subjects consisted of 133 women and 41 men; their mean age was 72.6 +/- 7.7 years (S.D.; range: 49 to 88) years. An examiner (neurologist) used the NPI to interview a caregiver familiar with the patient's everyday behavior. In 24 randomly selected patients interview was repeated by another examiner (psychiatrist) one month later, and test-retest reliability was evaluated. The Clinical Dementia Rating (CDR), the Mini-Mental State Examination (MMSE), and the Alzheimer's Disease Assessment Scale (ADAS) were used to assess the severity of the dementia and cognitive impairment.

RESULTS

The MMSE scores ranged from 5 to 29 (mean +/- SD = 19.0 +/- 4.8) and the ADAS scores ranged from 7 to 63 (24.3 +/- 10.9). The CDR score was 0.5 in 17 patients, 1 in 95 patients, 2 in 52 patients, and 3 in 10 patient. Test-retest reliability of each score was acceptably high, and the correlation coefficient for each score obtained by repeated assessments in this study was similar to the coefficient in the original report. Apathy was the most common behavior in the ten abnormal behavioral domains, and euphoria was the least common. The prevalence of abnormal findings was also comparable to the results in the original report. The total NPI scores and many of the NPI subscale scores were significantly correlated with both the severity of dementia and cognitive impairment.

CONCLUSIONS

This Japanese version of NPI, whose reliability and competency are comparable to those of the original version, is a reliable and useful tool for measuring neuropsychiatric disturbances in dementia patients.

[Magnetic resonance imaging of brainstem lesions in a case of neuro-Behçet disease]

We reported a 28-year-old man with multiple lesions in the brainstem which were clearly identified and followed up with MRI. He had been treated for Behçet uveitis using cyclosporine and colchicine during the past 5 years, and he acutely presented with fever and headache, followed left hemiparesis, dysarthria and dysphagia. MRI on admission revealed multiple lesions in the ventral pontine region which showed mixed-intensity on T1WI, high-intensity on T2WI and enhancement with Gd-DTPA. His clinical symptoms spontaneously and gradually improved, but more rapidly improved due to additional administration of corticosteroid. The lesions in the brainstem became smaller and finally rudimentary during two months after the onset of neurological symptoms.

Cholesterol and bile acid metabolism after selective portal vein ligation

AIM

To examine the regulatory effect of bile acid level on bile acid synthesis in the liver.

METHODS

The portal branch perfusing left lateral and median lobes of the liver was ligated in rats and the activities of hepatic microsomal cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme of bile acid synthesis, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, and intrahepatic concentrations of cholesterol and bile acids were determined in the liver lobes deprived of and supplied with portal blood on Days 0, 1, 2, 4, and 7 after selective portal vein ligation (SPVL).

RESULTS

In the portal vein (PV)-ligated lobes, liver weight decreased, hepatic cholesterol concentration was unchanged, and microsomal cholesterol concentration increased after SPVL. In the PV-nonligated lobes, liver weight increased, hepatic cholesterol concentration increased, and microsomal cholesterol concentration was unchanged. There were no significant differences in the activities of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase among the PV-ligated and PV-nonligated lobes and the sham-operated controls. Intrahepatic bile acid level increased significantly in the PV-nonligated lobes for 4 days after SPVL, whereas those were essentially constant in the PV-ligated and the sham-operated control liver. Despite significant changes in the concentrations of intrahepatic cholesterol and bile acid, no significant correlations were observed between these concentrations and the activities of cholesterol 7 alpha-hydroxylase.

CONCLUSIONS

SPVL causes atrophy and hypertrophy of the PV-ligated and nonligated liver lobes, respectively, without any significant changes in cholesterol and bile acid synthesis. Intrahepatic concentrations of bile acids and cholesterol have no regulatory effect on cholesterol 7 alpha-hydroxylase activity in the SPVL rat model.

Linkage map of Syrian hamster with restriction landmark genomic scanning

We have constructed the linkage map with precise genetic analysis of the Syrian hamster, Mesocricetus auratus, according to the restriction landmark genomic scanning (RLGS) spot mapping method. Although only 3.2-6.6% of the total RLGS spots between the two strains, ACN and BIO 14.6, showed genetic variance, 572 loci were found to be polymorphic. Out of 569 RLGS loci and 3 other loci, 531 were mapped with the backcross (ACN x BIO 14.6) F1 x BIO 14.6. The cumulative map was 1111.6 cM, indicating that the spots/loci are located throughout the genome at 1.94 cM intervals on average. Thus, RLGS provides us with a rapid tool to construct the genetic map of any species, even if it has less genetic variation.

A unique downregulation of h2-calponin gene expression in Down syndrome: a possible attenuation mechanism for fetal survival by methylation at the CpG island in the trisomic chromosome 21

To understand the effect of trisomic chromosome 21 on the cause of Down syndrome (DS), DNA methylation in the CpG island, which regulates the expression of adjacent genes, was investigated with the DNAs of chromosome 21 isolated from DS patients and their parents. A methylation-sensitive enzyme, BssHII, was used to digest DNAs of chromosome 21, and the resulting DNA fragments were subjected to RLGS (restriction landmark genomic scanning). Surprisingly, the CpG island of the h2-calponin gene was shown to be specifically methylated by comparative studies with RLGS and Southern blot analysis. In association with this methylation, h2-calponin gene expression was attenuated to the normal level, although other genes in the DS region of chromosome 21 were expressed dose dependently at 1.5 times the normal level. These results and the high miscarriage rate associated with trisomy 21 embryos imply that the altered in vivo methylation that attenuates downstream gene expression, which is otherwise lethal, permits the generation of DS neonates. The h2-calponin gene detected by the RLGS procedure may be one such gene that is attenuated.

Alteration of white matter MR signal intensity in frontotemporal dementia

PURPOSE

To determine the diagnostic potential of MR imaging to show white matter involvement in frontotemporal dementia.

METHODS

We evaluated MR signal intensity in cerebral white matter by visually inspecting and by quantitatively measuring signal intensity on MR images in 22 patients with frontotemporal dementia. The findings were compared with those in 22 age- and sex-matched patients who had had Alzheimer disease for the same length of time and with 16 age- and sex-matched healthy control subjects.

RESULTS

Patients with frontotemporal dementia had a significant increase in white matter signal intensity in the frontal and/or temporal lobes on T2- and proton density-weighted images. Visual inspection of regular proton density-weighted images and measurements made on the T2- and proton density-weighted images were sensitive to changes in white matter signal.

CONCLUSION

Increased MR signal intensity in the frontotemporal white matter on T2- and proton density-weighted MR images is a useful diagnostic sign of frontotemporal dementia and distinguishes this condition from Alzheimer disease.

Clinical significance of bcl-2 gene expression in human breast cancer tissues

The expression of estrogen receptor (ER) and bcl-2 (Bcl-2), an apoptosis protective oncogene, in normal and cancerous breast duct epithelia was immunohistochemically examined in fresh frozen tumor tissues from 142 Japanese breast cancer patients. The clinico-pathological characteristics and the disease free survival of the patients were analyzed. The expression of both the proteins was also observed in intraductal components of breast cancer. Although less than 1% of normal duct epithelia expressed ER, Bcl-2 was diffusely expressed. The expression of both these proteins in breast cancer significantly correlated with each other. Their expression significantly correlated negatively with tumor size but not with lymph node status. The papillo-tubular sub-type of invasive ductal carcinoma expressed Bcl-2 significantly more frequently than the solid-tubular sub-type. Patients with Bcl-2 expressing tumors survived without recurrence significantly more than those with tumors exhibiting reduced expression. Papillary-cribriform type intraductal components expressed both those proteins more often than the solid-comedo type.

Premorbid brain size as a determinant of reserve capacity against intellectual decline in Alzheimer's disease

OBJECTIVE

Both the magnitude of brain atrophy and premorbid brain size determine the volume of the brain affected by Alzheimer's disease. To examine the possibility that premorbid brain volume is a determinant of cognitive reserve in patients with Alzheimer's disease, the relation between diffuse brain atrophy and cognitive decline and the impact of premorbid brain size on cognitive decline were studied in patients with Alzheimer's disease.

METHOD

By measuring whole brain volume and intracranial volume in 60 patients with probable Alzheimer's disease, mild to moderate in severity, with the use of high-resolution magnetic resonance imaging and image processing, the authors studied the impact of premorbid brain volume and magnitude of diffuse brain atrophy on cognitive functions. On the basis of the normative brain-calvarium relationship derived from data an 28 healthy adults and the total intracranial volume measure of each patient, the magnitude of brain atrophy and premorbid brain volume were estimated.

RESULTS

After control for the effects of age, sex, and education as confounding factors, it was found that the Alzheimer's disease patients' intelligence was correlated both positively with premorbid brain volume and negatively with magnitude of brain atrophy, while impairments in language and memory were correlated with magnitude of brain atrophy but not with premorbid brain volume.

CONCLUSIONS

These findings partially support the hypothesis that premorbid brain volume is a determinant of reserves against intellectual decline in Alzheimer's disease.

Osmotic modulation in glutamatergic excitatory synaptic inputs to neurons in the supraoptic nucleus of rat hypothalamus in vitro

To clarify influence of osmotic stimulation on the excitatory synaptic inputs to the neurosecretory cells of the supraoptic nucleus (SON), the blind patch technique was used in rat hypothalamic slice preparations. Stable whole-cell recordings were made from 22 neurons in the SON. To observe spontaneous excitatory postsynaptic currents (sEPSCs) in the SON neurons, membrane potentials were clamped between -50 and -90mV. The effects of hypertonic stimulation on the frequency of the sEPSCs were tested in 18 SON neurons. Bath application of mannitol 30 or 60 mM increased the frequency of the sEPSCs. During the application of mannitol (60 mM), the frequency of the sEPSCs increased in 12 of 15 neurons without a change in amplitude. Hypertonic stimulation with NaCl (30 mM) had similar effects to that of mannitol. The increased frequency of miniature EPSCs (mEPSCs) during mannitol application persisted in the presence of TTX in all 8 SON neurons tested with no change in amplitude. Both the non-NMDA antagonist CNQX at 10-30 microM (n = 6) and the non-selective glutamate antagonist kynurenic acid at 1 mM (n = 3) almost completely blocked the EPSCs while the NMDA antagonist AP-5 at 10 microM had no effect on the frequency of the EPSCs in the 4 neurons tested. During application of CNQX, mannitol (60 mM) was added to the perfusion medium in 3 SON neurons. Under these conditions, mannitol had no effect on the frequency of EPSCs. We conclude that hypertonic stimulation directly influences glutamatergic inputs to the neurosecretory cells of the SON by an action on the presynaptic terminals and enhances the excitatory synaptic events.

Simultaneous quantitative analyses of c-erbB-2 protein, epidermal growth factor receptor, cathepsin D, and hormone receptors in breast cancer

The overexpression of c-erbB-2 protein (ErbB2), epidermal growth factor receptor (EGFR), and/or cathepsin D (CD) in breast cancer is known to be a poor prognostic factor. Eighty frozen breast cancer specimens obtained at the initial operation were examined for ErbB2, EGFR, and CD by immunohistochemical assay (ICA) and enzyme immunoassay (EIA). Estrogen and progesterone receptors (ER and PgR) were measured simultaneously by EIA. The mean values +/- 1SD for ErbB2, EGFR and CD were 141 +/- 400 U/mg membrane protein (range: 0-3385), 4.88 +/- 4.33 fmol/mg membrane protein (range: 0-21.1), and 47.1 +/- 32.8 pmol/mg cytosol protein (range: 4.7-182), respectively. The percentage of specimens positive for ErbB2, EGFR, and CD was 12.5, 38.8, and 35%, when the tentative cutoff value were used as 200 U/mg protein, 5 fmol/mg protein, and 50 pmol/mg protein, respectively. These E1A results were correlated with ICA, EGFR and ER were negatively correlated. Although the prognostic value of ErbB2 and EGFR was superior to hormone receptors, ErbB2 and EGFR were interior as predictors compared with lymph node involvement and tumor size. Quantitation of ErbB2, EGFR, and CD can be performed readily using the same specimen in which hormone receptors are measured.

Leiomyosarcoma of the colon presenting as acute suppurative peritonitis

A surgical case of leiomyosarcoma arising from the ascending colon, presenting as acute suppurative peritonitis, is herein described. A 70-year-old woman complaining of lower abdominal pain presented to our clinic on October 12, 1994. She was admitted with a tentative diagnosis of peritonitis. At emergency laparatomy, purulent intraabdominal fluid was present, and a fist-sized mass was seen in the ascending colon just proximal to the hepatic flexure. A right hemicolectomy was thus performed based on a diagnosis of perforating colon cancer. The histologic findings were consistent with leiomyosarcoma with abscess formation in and around the tumor. Five mitotic figures per field were observed at 10x magnification. Immunohistochemical studies revealed immunoreactivity for alpha-smooth muscle antigen (alpha-SMA), vimentin, and desmin. After reviewing the clinicopathologic characteristics of colon leiomyosarcoma as described in 78 Japanese cases and 70 cases from the foreign literature, we thus propose that colon leiomyosarcoma frequently arises from the transverse colon. In addition, our case also represents the only reported case in Japan in which an adult patient underwent a successful operation for perforated leiomyosarcoma of the colon.

[A resected case of bronchogenic cyst of the left hemidiaphragm with elevated serum CA19-9]

A rare case of bronchogenic cyst of the left hemidiaphragm is reported. A 53-year-old woman referred to our institution for an abnormal shadow on chest roentgenogram. Chest X-ray showed a 6 x 6 cm mass in the left lower lung filed. The margin of the mass was clear and the surface was smooth. The lateral view showed a mass on the diaphragm with the extrapleural sign. Chest CT demonstrated the mass as a multi loculated cyst. Celiac angiography demonstrated the branch of the inferior diaphragmatic artery at the margin of the mass. Her serum CA19-9 level was 470 U/ml. The patient underwent surgical exploration. Operative findings showed the smooth surface mass was on the diaphragm covered with pleura. Resected tumor was large as 7.5 x 6.5 x 4.0 cm. The surface was smooth and white-yellowish, and the cut surface presented a multi loculated cyts. Histopathological examination showed a bronchogenic cyst. CA19-9 in the cyst fluid was elevated as 445,900 U/ml. The serum CA19-9 level returned to normal after the operation.

[Association between sleep apnea syndrome and coronary artery disease]

Patients with sleep apnea syndrome often suffer from cardiovascular disease, but the incidence of coronary artery disease (CAD) with coronary spasm in these patients is not known. In the present study, 14 of 37 men with sleep apnea syndrome diagnosed by all-night polysomnography were suspected to also have CAD, based on the results of non-invasive clinical examinations. Coronary angiography confirmed the diagnosis of CAD either organic stenosis or coronary spasm in 8 of the 14 patients. Those 8 did not differ significantly from the 21 patients without CAD, with regard to coronary risk factors or to the severity of their sleep apnea (apnea index, 4% desaturation ratio, and nadir of SaO2). Eleven patients received intracoronary injections of acetylcholine, which induced coronary spasm in 4 (36.4%) and coronary contraction in 2 (18.2%). Coronary spasm was induced in 4 of the patients with CAD (50.0%). Although the pathophysiologic link between sleep apnea syndrome and CAD is still unclear, these results suggest that patients with this syndrome frequently suffer from CAD, particularly from coronary spasm.

The internal biliary fistula--reappraisal of incidence, type, diagnosis and management of 33 consecutive cases

To reevaluate the current features of spontaneous internal biliary fistulas, we reviewed 1,929 consecutive patients who had been treated for biliary tract diseases during the recent 12-year period. Thirty-three patients had internal biliary fistulas and the incidence was 1.9%. Of 33 patients, 20 were women and 13 were men with the average age 63 years, and their mean duration of illness was 4 years. A total of 37 fistulas were found and the most common type was choledochoduodenal (62%), followed by cholecystoduodenal (19%), cholecystocholedochal (11%) and cholecystocolonic (8%) fistulas. Internal biliary fistulas of thirty-one patients were caused by biliary stones and those of two patients by malignant tumors. All of the 17 bile samples examined were bacteria positive and the majority of calculi were brown pigment stones. All of the choledochoduodenal fistulas were correctly diagnosed by endoscopic retrograde cholangiography. In 14 patients with cholecystoenteric or cholecystocholedochal fistulas, direct evidence of the internal fistula was obtained only in 7 patients (50%) preoperatively. Pneumobilia, a small atrophic gallbladder adherent to the neighboring organs and a history of spontaneous disappearance of jaundice in elderly patients may indicate the presence of a cholecystoentric fistula. Since the preoperative diagnostic rate for internal biliary fistula involving the gallbladder is still low, care is necessary before and at the time of surgery especially during laparoscopic cholecystectomy for elderly patients with cholelithiasis.

PACAP type I receptor gene expression in the paraventricular and supraoptic nuclei of rats

We have examined the distribution of pituitary adenylate cyclase-activating polypeptide (PACAP) type I receptor gene expression in the rat paraventricular (PVN) and supraoptic nuclei (SON) using in situ hybridization histochemistry. PACAP type I receptor gene was expressed moderately in the whole area of the PVN and the SON. In particular, PACAP type I gene transcripts were found in both the magnocellular and the parvocellular parts of the PVN. The results are consistent with the hypothesis that neurosecretory cells in the PVN and the SON might be modulated by PACAP through PACAP type I receptor.

Deconjugation of bilirubin accelerates coprecipitation of cholesterol, fatty acids, and mucin in human bile--in vitro study

To examine the initial step of brown pigment gallstone formation, sterile human gallbladder bile samples were incubated with or without beta-glucuronidase in vitro. Enhanced bilirubin deconjugation achieved by adding beta-glucuronidase significantly accelerated the formation of a precipitate that contained bilirubin (28.2 +/- 3.8% of dry weight), cholesterol (14.3 +/- 5.2%), free fatty acids (12.0 +/- 1.3%), and glycoprotein (10.0 +/- 6.7%). Both the composition and scanning electron microscopic appearance of the precipitate were similar to these features in brown pigment gallstones. The cholesterol saturation index and nucleation time in the supernatant did not change with various incubation periods. The weight ratios of bilirubin to cholesterol in the precipitates correlated with those in bile (r = 0.76; P = 0.017). Gel chromatography of the precipitate showed high molecular weight glycoprotein to be the major constituent. Bilirubin, cholesterol, fatty acids, and mucin were found to coprecipitate in accordance with bilirubin deconjugation, which process may play an important role in an early stage of the formation of brown pigment gallstones.