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J D Ostrow

Publications and source records attributed to J D Ostrow.

At least 19 recordsLinked to original sources
PubMed1992

Isolation of a calcium-regulatory protein from black pigment gallstones: similarity with a protein from cholesterol gallstones.

We have previously isolated from 13 cholesterol gallstones a low molecular weight acidic bili-protein that inhibited the precipitation of calcium carbonate in vitro. We now report the isolation of a similar protein from seven black pigment gallstones. Cholesterol was removed from the stones by Soxhlet apparatus with methyl t-butyl ether, and bile acids were extracted with methanol. The protein was purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after demineralization of the stones with ethylenediaminetetraacetate. Structural and functional properties of the protein from the black stones that were similar to the protein from the cholesterol stones included the following: (a) an apparent molecular weight of about 5 kD; (b) a high content of acidic (19.8%) and hydrophobic (50.1%) amino acids with a low content of basic residues (8.4%) and little sulfide-containing amino acids (1.9%); (c) an inhibitory effect on both the initiation and growth of calcium carbonate crystals in vitro; and (d) very tight (possibly covalent) binding of a diazo-positive yellow pigment, presumably bilirubin, with maximum spectral absorbance at 410 nm. The structural and functional similarities of these bili-proteins from black pigment and cholesterol gallstones and their striking effects on calcium carbonate precipitation in vitro suggest that they play a common role in the regulation of precipitation of calcium salts during the formation of both types of gallstones.

Calcium Carbonate↗
PubMed1992

Epitope mapping of the human biliary amphipathic, anionic polypeptide: similarity with a calcium-binding protein isolated from gallstones and bile, and immunologic cross-reactivity with apolipoprotein A-I.

Biliary amphipathic anionic polypeptide (APF) the major protein of the pigment-lipoprotein complex in bile, and calcium-binding protein (CBP) from gallstones are both small (less than 10 kDa), highly acidic, amphipathic proteins present in bile and closely associated also with pigmented areas in human gallstones. Polyclonal antibodies against APF have shown cross-reactivity with plasma high density lipoproteins (HDL). This study examines the hypothesis that APF and CBP might be closely related or even identical, and might also share common epitopes with the larger apoA-I (23 kDa). To assess this, immunoreactivity of the three delipidated, highly purified proteins was determined against a panel of 12 monoclonal antibodies (MAbs) prepared against APF and a panel of 4 MAbs against apoA-I. APF was isolated from bile by zonal ultracentrifugation. CBP was isolated from proteins precipitated from bile by CaCl2, as well as from the calcium bilirubinate shells of cholesterol gallstones, by extraction successively with methyl-t-butyl ether, methanol, and Na2EDTA, followed by Sephadex G-25 chromatography and two-stage preparative SDS-PAGE. ApoA-I was prepared by two types of chromatography: Sephacryl S200 chromatography and heparin-chromatographic immunoaffinity. Specific polyclonal antibodies to APF and apoA-I were prepared from immunized rabbits. MAbs to APF and apoA-I were prepared by immunization of mice, using standard hybridoma technique. Western blotting of APF and CBP in 15% SDS-PAGE yielded one band with an apparent molecular weight of 6.5 kDa, which, along with apoA-I, was immunostained by polyclonal antibodies to APF and apoA-I. Using 12 MAbs against APF with three types of ELISA (direct antigen binding, competitive antigen displacement, and epitope competition between antibodies), it was shown that APF and delipidated apoA-I shared six epitopes, three of which were detected also on the surface of intact HDL particles. Six other epitopes were present in APF but not apoA-I, four of which were exposed on the surface of HDL. Four MAbs against apoA-I reacted with APF and CBP. Amino acid analyses of APF and CBP were similar with 20-23% acidic and 7-11% basic amino acids and low contents of cysteine, methionine, and tyrosine; both differed from apoA-I in containing isoleucine and cysteine. Using ELISA and one MAb (no. 32) against APF, this polypeptide was detected in human plasma HDL, the pigment-lipoprotein complex in the bile of humans, dogs, and rats, and in both pigment and cholesterol gallstones.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Ionization and self-association of unconjugated bilirubin, determined by rapid solvent partition from chloroform, with further studies of bilirubin solubility.

Our studies of equilibrium solubilization of crystals of unconjugated bilirubin (UCB) in buffered aqueous NaCl (1988. J. Lipid Res. 29: 335-348) suggested that the two carboxylic pKa values were 6.8 and 9.3 and the solubility of UCB diacid was 0.1 microM. These data, however, were not ideal, due to possible effects of crystal size, metastability, 96-h incubation times with formation of polar derivatives, impurities in the bilirubin, and imprecision of analyses at low concentrations of UCB ([UCB]). In the present study, designed to determine the pKa values and self-association of UCB, these problems were minimized by solvent partition of UCB from solution in CHCl3 into buffered aqueous NaCl. There was no crystal phase. Equilibrium was attained rapidly (10 min); UCB and CHCl3 were highly purified; and accurate diazo assay of low [UCB] in the aqueous phase, [Bw], was achieved by concentrating the UCB through back-extraction into a small volume of CHCl3. By determining effects on partition rations of varying the [UCB] in the CHCl3 phase, [Bc], we could assess also the self-association of UCB species in the aqueous phase. Partition ratios (P = Bw/Bc) did not differ between initial and repeat extractions, indicating insignificant concentrations of polar UCB derivatives. Similar P ratios were obtained when equilibrium was approached from a supersaturated aqueous phase. At 21-25 degrees C, mu = 0.15, the data (n = 76) fit the equation: log P = log Po + log[1 + 10(pH-A) + 10(2pH-B) + Bc.10(4pH-D)]; the bracketed terms reflect P for H2Bo (diacid), HB- (monoanion), B= (dianion), and (B=)2 dimer, respectively. Computer-fitted values for constants (+/- SD) were: Po = P for H2Bo = 5.79 x 10(-5); A = pK1 = 8.12 +/- 0.23; B = pK1 + pK2 = 16.56 +/- 0.10; pK2 = 8.44 +/- 0.33; D = pk22 + 2(pK1 + pK2) -log(2Po) = 37.64 +/- 0.07, and k22 = 0.26 microM-1 [formation constant of (B=)2 dimer]. In ancillary studies, multiple cycles of direct dissolution of UCB crystals revealed a progressive decrease in aqueous solubility of UCB as fine crystals were removed; this effect was minimal in CHCl3. Unlike in water, moreover, varied UCB crystal forms had similar solubilities in CHCl3, with [Bc] = 1.14 mM at saturation. As determined from [Bc]sat.Po, the aqueous solubility of H2Bo was 66 nM.(ABSTRACT TRUNCATED AT 400 WORDS)

Bilirubin↗
PubMed1991

Canine bile contains anticrystallization factors that inhibit precipitation of calcium carbonate.

Previous studies have strongly suggested that human bile contains a substance(s) that interferes with the precipitation of calcium phosphate and carbonate from solution. These studies, however, did not distinguish between calcium binding by biliary constituents resulting in decreased calcium carbonate saturation (alterations in solution thermodynamics) and true inhibition of calcium salt precipitation by kinetic factors. Because our recent studies have shown that canine common duct bile is always supersaturated with calcium carbonate (thermodynamically at risk for precipitation), we hypothesized that it must contain kinetic factors that inhibit formation and/or growth of calcium carbonate crystals. Effects of canine bile, bovine albumin and the bile salt taurocholate on calcium carbonate precipitation were studied in highly supersaturated solutions of calcium carbonate that spontaneously undergo rapid precipitation. Measured free ionized calcium concentrations, [Ca++], and calculated calcium carbonate saturation indices were compared in test solutions and controls to evaluate the thermodynamic effects of test solutions on the degree of saturation in the assay system. It is shown that addition of only 0.2 ml of normal canine gallbladder bile to the assay system (a 1:101 dilution of biliary components) abolished precipitation. A lesser inhibitory effect (a decrease in the rate of precipitation) was observed when gallbladder bile was diluted but was lost after 10-fold dilution. Canine common duct bile caused a decrease in the rate of precipitation similar to diluted gallbladder bile. In contrast, sodium taurocholate (250 mmol/L), the major bile salt in the dog, and albumin (1.5 gm/L), the most abundant protein in bile, had only a minimal inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Natural history and significance of esophageal squamous cell dysplasia.

Balloon-mesh cytologic screening for esophageal cancer done in 255 asymptomatic high-risk United States veterans (age greater than 40 years, ethanol abuse for greater than 20 years, and cigarette smoking greater than 20 pack years) identified 37 patients with squamous cell dysplasia. Of the 37 patients with dysplasia, 28 were re-evaluated prospectively at 6-month intervals for up to 36 months by balloon-mesh cytology, esophagoscopy with vital staining and biopsies, chest radiographs, oropharyngeal examination, and indirect laryngoscopy. During prospective follow-up evaluation, cytology specimens were repetitively normal in 16 patients (57%), showed inflammatory changes in eight patients (29%), persisted as dysplasia in two patients (7%) (both had endoscopic and histologic evidence of esophagitis), and progressed to carcinoma in two patients (7%) (one esophageal, one laryngeal). Although histologic findings concurred with the resolution of dysplasia, biopsy specimens were characterized by a similar difficulty in distinguishing dysplasia from inflammation. Erroneous histologic diagnoses of carcinoma in situ were made in two patients with reflux esophagitis evident endoscopically and confirmed during the course of a 24-36 month follow-up period. The authors conclude that squamous cell dysplasia detected by balloon-mesh cytology is seldom a precursor of esophageal cancer in the high-risk U.S. population but, rather, is often related to esophagitis. Thus, balloon-mesh cytology has limited use as a screening method for the early detection of esophageal cancer in the United States.

Adult↗
PubMed1990

Unconjugated bilirubin and cholesterol gallstone formation.

Cholesterol gallstones usually have small amounts of pigment at their centers and often have diffuse pigmentation or pigmented layers alternating with cholesterol layers and/or pigmented rims associated with calcium carbonate (eggshell calcification). The pigments are primarily monomeric calcium salts of unconjugated bilirubin anions and/or an insoluble, black, network polymer of tetrapyrroles. Bilirubin presumably can precipitate only if bile is supersaturated with calcium bilirubinates. Among various in vitro model systems, the aqueous solubilities and pK'a values for unconjugated bilirubin differ greatly. It is therefore not known whether normal bile is saturated with unconjugated bilirubin. However, all systems indicate that unconjugated bilirubin is solubilized by binding to bile salt monomers and oligomers, as well as micelles; marked metastable supersaturation of unconjugated bilirubin can occur in the presence of bile salt micelles, and both pK'a values of unconjugated bilirubin are greater than 6.0, probably because of internal hydrogen-bonding of the--COOH groups. Lecithin decreases equilibrium solubilization of unconjugated bilirubin crystals but enhances metastable supersaturation of unconjugated bilirubin. Calcium ions form insoluble salts with unconjugated bilirubin monoanions and dianions but soluble complexes with bilirubin conjugates. The solubility products of the calcium bilirubinate salts suggest that normal hepatic bile is not saturated with CaB or Ca(HB)2 but that gallbladder bile may be supersaturated with Ca(HB)2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Preparation and properties of bilirubin photoisomers.

Polar photoisomers of bilirubin were formed by irradiation of bilirubin in chloroform solution in the absence of O2. Two pairs of compounds were isolated with molecular weights identical with bilirubin. One pair reverted to bilirubin in polar media and gave chemical reactions similar to bilirubin; the other pair were not reconverted into bilirubin by chemical means and gave reactions distinct from those of bilirubin. However, both groups were reconverted into bilirubin by irradiation in chloroform solution in the absence of O2. The probable role of these photoisomers in the catabolism of bilirubin during phototherapy of neonatal jaundice is discussed.

Bilirubin↗
PubMed1978

Inaccuracies in measurement of conjugated and unconjugated bilirubin in bile with ethyl anthranilate diazo and solvent-partition methods.

A criticial evaluation was made of the ethyl anthranilate diazo and two solvent-partition methods for the determination of conjugated and unconjugated bilirubin in human and rat bile. The ethyl anthranilate diazo reagent, which reacts only with conjugated bilirubin in serum, also diazotized a variable proportion of unconjugated bilirubin in bile and thus overestimated the concentration of monoconjugates. With the Weber-Schalm and modified Folsch solvent-partition methods applied to human or rat bile, 4--9% of added 14C-labelled unconjugated bilirubin partitioned with the conjugated bilirubin in the upper phase, and 4--9% of added 14C-labelled conjugated bilirubin partitioned into the lower phase. With dog bile, the spill-over of 14C-labelled bilirubin into the lower phase was 9--11%. Analysis of azopigments from the Weber-Schalm partition confirmed that over two-thirds of the bilirubin in the lower phase represents monoconjugates, principally the less-polar monoxylosides and monoglucosides. These solvent-partition methods thus overestimate the concentration of unconjugated bilirubin in bile.

Animals↗
PubMed1978

Pigment gallstone composition in cirrhotic and noncirrhotic subjects.

The composition of pigment gallstones from patients with and without cirrhosis was compared. Carbonate-containing pigment stones were distinguished from noncarbonate stones by infrared spectroscopy. Calcium was the major cation of each stone group. The major anion in noncarbonate pigment stones was bilirubinate or phosphate, but was carbonate in carbonate stones. The composition of pigment stones from cirrhotic and noncirrhotic patients was similar except that significantly less carbonate was present in carbonate stones, and less pigment (bilirubinate) was present in noncarbonate stones from noncirrhotics. These data suggest that irrespective of the presence of cirrhosis, the formation of noncarbonate pigment stones involves the selective precipitation of calcium bilirubinate and phosphate, whereas carbonate stone formation involves the selective precipitation of calcium carbonate.

Age Factors↗
PubMed1978

Stimulation of bilirubin catabolism in jaundiced Gunn rats by an induced of microsomal mixed-function monooxygenases.

The homozygous, jaundiced Gunn rat compensates for its inability to form bilirubin conjugates by production of polar bilirubin metabolites which can be excreted in the bile without conjugation. To assess whether microsomal mixed-function monooxygenases might be involved in formation of these metabolites, a potent inducer of these enzymes, 2,3,7,8-tetrachlorodibenzo-p-dioxin, was administered to Gunn rats in a single intraperitoneal dose of 10 mug/kg. Four to 6 days after treatment, plasma bilirubin levels had declined by a mean of 61%, whereas no significant change was observed in control Gunn rats that received only the dioxane vehicle. Use of tracer [(14)C]bilirubin showed that the decline in plasma bilirubin was the result of a 7-fold increase in fractional bilirubin turnover which reduced the bilirubin pool to an average of 11% of the control values. In the new steady state, total bilirubin turnover was unaltered. The accelerated fractional bilirubin turnover was associated with augmented biliary excretion of polar bilirubin metabolites and a 16-fold increase in hepatic benzo[a]-pyrene hydroxylase activity. Hepatic bilirubin-UDPglucuronate transferase was not induced, and no bilirubin conjugates appeared in the bile. This chemical simulation of the alternate pathways of bilirubin catabolism by the inducer suggests that microsomal cytochrome P(448)-dependent monooxygenases may be involved in the formation of the polar bilirubin metabolites excreted by the Gunn rat.

Animals↗
PubMed1977

Pigment gallstones.

Pigment gallstones are defined as any dark brown-to-black stone, consisting of calcium salts of bilirubin, phosphate, carbonate and other anions, and can be separated into carbonate- and noncarbonate-containing groups. Pigment stones predominate in the rural Orient, in cirrhosis, and in elderly United States patients undergoing cholecystectomy. Clinical associations include bile duct obstruction, stasis, and possibly hemolysis. Of pigment stones, 50% are radioopaque and account for two-thirds of all opaque stones. The concentrations of bile salts, phospholipids,, cholesterol, and total bilirubin in bile are similar to normal levels, but the concentration of unconjugated bilirubin is increased in the bile of some patients. Increased unconjugated bilirubin in bile may be caused by increased hydrolysis of excreted conjugated bilirubin. Unconjugated bilirubin is solubilized by bile salts, but the interaction is primarily nonmicellar. Ionized calcium and pH are important determinants of solubility. Sulfated glycoproteins, excreted in increased amounts in patients with cholelithiasis, may be the site of pigment stone precipitation because these compounds bind calcium salts tightly. E coli is frequently cultured from pigment stones in Japan but not in the United States; thus, bacterial beta-glucuronidase may be important in stone formation in Japan but probably not in the West. Stasis leads to increased calcium secretion and to increases in the concentration of sparingly soluble compounds that may then precipitate. Incomplete emptying of the gallbladder may result in the same concentration process. Unsaturated fats and chronic vagal stimulation cause pigment stone formation in animals. At present, surgery is the only treatment for pigment lithiasis.

Adolescent↗
PubMed1977

Pigment versus cholesterol cholelithiasis: identification and quantification by infrared spectroscopy.

We previously reported that 27% of 92 cholecystectomized patients had pigment stones (Am J Dig Dis 19:585-590, 1974). Using standard biochemical methods, we found that cholesterol accounted for an average of 77% of the dry weight of cholesterol stones, but that unconjugated bilirubin represented a mean of only 7% of pigment stones. This quantitation of pigment stones was limited because approximately 66% of their weight was insoluble. To characterize pigment and cholesterol stone composition further, we used infrared spectroscopy--a technique requiring neither crystallinity nor solubilization--to quantitate pigment, carbonate, and cholesterol in gallstones. Other organic and inorganic components of stones were measured by standard methods. By infrared spectroscopy, two types of pigment stones were identified: carbonate-containing and noncarbonate pigment stones. Carbonate pigment stones contained significantly more calcium, carbonate, and phosphate, but less pigment than noncarbonate stones. Compared to our initial report, the total measured components of all pigment stones were increased 6-fold from 10 to 63%. Cholesterol was the major component of cholesterol stones by chemical assay or infrared spectroscopy. Among five cholesterol stones with limited solubility, 80% of the insoluble residue was identified as cholesterol by infrared spectroscopy. This study extends our knowledge of pigment stone and cholesterol stone composition by the use of quantitative infrared spectroscopy in conjunction with standard biochemical methods; furthermore, it confirms that pigment and cholesterol stones differ in composition and form by different mechanisms.

Carbonates↗
PubMed1977

Hemoccult testing.

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Blood Chemical Analysis↗