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Biomedical subjects

H Z Park

Publications and source records attributed to H Z Park.

14 recordsLinked to original sources
PubMed1995

Structure and composition of primary intrahepatic stones in Korean patients.

We have analyzed the chemical composition of primary intrahepatic stones from 72 Korean patients. Two types of concretions have been identified: brown pigment (calcium bilirubinate) stones and black-colored mixed stones. Brown pigment stones were found in 68% of all cases and the remainder (32%) consisted of mixed stones. Intrahepatic mixed stones had mean cholesterol and bilirubin contents of 46.6% and 25.9%, respectively, whereas calcium bilirubinate stones had mean cholesterol and bilirubin contents of 14.1% and 43.6%, respectively. Intrahepatic mixed stones had a smooth black-colored surface and on cross section, exhibited a distinct outer shell surrounding an inner yellow, cholesterol-rich body. The finding of intrahepatic mixed stones with high cholesterol content suggests that primary hepatolithiasis may result from at least two different conditions or disorders and points to different approaches to their treatment.

Adult↗
PubMed1992

Biliary sludge as a cause of acute pancreatitis.

BACKGROUND: In about 20 to 40 percent of cases of acute pancreatitis, no cause can be found, and these are labeled idiopathic. In this study, we sought to determine the frequency with which patients with acute idiopathic pancreatitis have biliary sludge, a suspension of cholesterol monohydrate crystals or calcium bilirubinate granules that is found predominantly in the gallbladder. METHODS: Between 1980 and 1988, we prospectively studied 86 patients who had acute pancreatitis. In patients with no known cause of pancreatitis and no ultrasonographic evidence of gallstones or dilatation of the biliary ducts, we determined how often biliary sludge was present and its subsequent fate by repeated microscopical examinations of bile samples and abdominal ultrasonography. The outcome of patients treated by cholecystectomy or papillotomy was compared with that of untreated patients. RESULTS: The pancreatitis was considered idiopathic in 31 of the 86 patients (36 percent), of whom 23 had microscopical evidence of biliary sludge. Biliary sludge was detected by ultrasonography in only 11 of the 23 patients (48 percent). The sludge detected by ultrasonography was composed of calcium bilirubinate granules in 10 and cholesterol monohydrate crystals in 1 (P = 0.003). Calcium bilirubinate granules were found more frequently in men (nine men vs. four women, P less than 0.001). Of the 21 patients in whom biliary sludge was the only finding (2 patients also had dilasted bile ducts when restudied), the 6 treated by cholecystectomy and the 4 treated by papillotomy had fewer recurrences of acute pancreatitis during follow-up (up to seven years) than the 11 untreated patients (P = 0.011). The presence of biliary sludge appeared to increase the likelihood of recurrent attacks of pancreatitis (P = 0.020). CONCLUSIONS: Biliary sludge is an underestimated cause of acute idiopathic pancreatitis.

Acute Disease↗
PubMed1992

A calcium-binding protein in bile and gallstones.

Calcium salts are often present in the center of all types of gallstones. Matrix proteins are known to be essential for biomineralization and may therefore also be important in the formation and growth of gallstones. Other researchers have described an anionic peptide fraction of a biliary lipoprotein complex in bile and a low-molecular weight acidic glycoprotein present in gallstones. Our goal was to determine whether such a protein was present in bile and whether this protein has any calcium-binding properties. We identified a pigment-associated, highly acidic protein that precipitates from bile on addition of CaCl2 0.5 mol/L. In addition, the protein is selectively concentrated in cholesterol and pigment stones. We have, therefore, confirmed the findings of these other researchers, and we have extended the study of this protein's interactions with calcium. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrates a single band (molecular weight < or = 14 kD) that reacts positively with cationic stains. The protein was shown to inhibit the precipitation of CaCO3 from a supersaturated solution. The capacity to bind calcium was further confirmed by autoradiography with 45Ca++ and by a membrane adsorption-binding assay. Calcium-induced aggregation was demonstrated by equilibrium dialysis and by quasielastic light scattering studies. Protein measured by Lowry's assay method and amino acid analysis constitutes only 2% to 4% of the harvested material. We speculate that a substantial lipid component may also be present.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1991

Ceftriaxone-associated gallbladder sludge. Identification of calcium-ceftriaxone salt as a major component of gallbladder precipitate.

Ceftriaxone, a third-generation cephalosporin, is partially excreted into bile. With its clinical use, the formation of gallbladder sludge detected by ultrasonography has been reported. Four surgical specimens were examined and no gallstones were found. Instead, fine precipitates of 20-250 microns were present. Microscopically, there was a small number of cholesterol monohydrate crystals and bilirubin granules among an abundant amount of granular-crystalline material that was not morphologically cholesterol monohydrate crystals. The chemical composition of the precipitates (n = 4) was determined. There was a small amount of cholesterol (1.7% +/- 0.8%) and bilirubin (13.9% +/- 0.74%). The major component of the precipitate was a residue. On further analysis using thin-layer chromatography, high-performance liquid chromatography, and electron microprobe analysis, the residue was identified as a calcium salt of ceftriaxone. The residue also had identical crystal morphology and chromatographic elution profile as authentic calcium-ceftriaxone standards. It is concluded that ceftriaxone, after excretion and being concentrated in the gallbladder bile, can form a precipitate. The major constituent has been identified as a ceftriaxone-calcium salt.

Bile↗
PubMed1991

Isolation and partial characterization of a soluble mucin in human pancreatic juice.

Morphological and histochemical abnormalities in pancreatic mucin occur in many pancreatic disorders. However, the composition of pancreatic mucin is poorly understood. Purified mucin was isolated from pure pancreatic juice by sequential chromatography on Sepharose CL-2B and CL-4B followed by CsCl density gradient ultracentrifugation. The mucin preparation consists of 24% protein and 73% carbohydrate. Reduction of the macromolecule (greater than 2 x 10(6)) by mercaptoethanol resulted in the formation of subunits of molecular weight 500,000 and released several small molecular weight proteins, including a glycoprotein of an average molecular weight of 116,000. Cellulose acetate electrophoresis separated the mucin into three species of different staining properties for periodic acid-Schiff reagent and Alcian blue, suggesting the presence of microheterogeneity with respect to sulphation and sialation. Threonine, serine, and proline composed 48% of the total amino acids, while the oligosaccharide moiety contained N-acetylglucosamine, N-acetylgalactosamine, fucose, galactose, sialic acid, and sulphate. We also detected the presence of C16:0 and C18:0 fatty acids which were probably noncovalently bound to the pancreatic mucin.

Adolescent↗
PubMed1988

Effect of pepsin on partially purified pig gastric mucus and purified mucin.

Partially purified native-pig gastric mucus and purified pig gastric mucin, prepared by column chromatography and caesium chloride (CsCl) density-gradient ultracentrifugation, were subjected to pepsin digestion. The products of peptic digestion were chromatographed on Sepharose CL-2B, and fractions were assayed for carbohydrate by the periodic acid-Schiff reaction. The polymeric gastric mucin in the purified mucin samples was readily degraded by pepsin. In sharp contrast, the polymeric mucin in the partially purified mucus was relatively resistant to pepsin digestion. In 45 min, pepsin degraded 40% of the polymeric mucin in the purified samples, whereas it produced no significant degradation (less than 10%) in the partially purified mucus samples. In partially purified gastric mucus, treated with CsCl but not fractionated by ultracentrifugation, digestion with pepsin was also slow and incomplete. This showed that differences in susceptibility between partially purified and purified preparations are not due to the chaotropic effects of CsCl. In addition, the recombination of low-density nonmucin fractions in CsCl ultracentrifugation with the mucin also resisted pepsin digestion. Finally, we have shown that the low-density fractions in mucus exhibited a strong inhibitory effect of peptic activity in vitro. We conclude that under our experimental conditions, pepsin has little effect on partially purified mucus, and our findings indicate an inhibitor of peptic digestion is present in native gastric mucus. It is likely, but unproven, that this inhibitor is a noncovalently bound lipid present in the low-density fraction.

Animals↗
PubMed1987

Partial characterization of a nonmicellar system of cholesterol solubilization in bile.

We have shown that there were two distinctly separate cholesterol-containing fractions in human hepatic and gallbladder bile. In addition to mixed micelles that were composed of bile salts, cholesterol, and phospholipids and measured at approximately 25 A by quasi-elastic light scattering spectroscopy, there was a nonmicellar fraction made up of cholesterol and phospholipids with no, or only trace amount of bile salts. This fraction had a mean hydrodynamic radius of 600 A. When studied with electron microscopy, the fraction consisted of particle spherical in shape that measured 900-1,300 A in diameter and were monodisperse. This form of cholesterol had a low buoyant density of less than 1.05 g/ml by density gradient ultracentrifugation and eluted as a macromolecular aggregate (mol wt greater than 200,000) employing Sephadex G-75 chromatography. The quantity of nonmicellar cholesterol in bile correlated positively with the cholesterol saturation index (r = 0.649; P less than 0.001) and inversely with relative bile salt concentration (r = -0.572, P less than or equal to 0.03) and total lipid concentration (r = -0.844, P less than 0.0001). In vitro and in vivo addition of bile salts resulted in a shift of nonmicellar cholesterol to micellar cholesterol. In hepatic bile, nonmicellar cholesterol was the predominant and sometimes the exclusive form of cholesterol transport. When nucleation experiments were performed on gallbladder bile samples, the cholesterol that had nucleated were almost exclusively derived from the nonmicellar fraction.

Bile↗
PubMed1976

Light microscopic localization of labile calcium in hypertrophied chondrocytes of long bone with alizarin red S.

A method which localizes labile 5% ethylene glycol-bis-(beta-amino-ethyl ether)N-N'-tetraacetic acid-removable calcium in spherules within hypertrophied chondrocytes and in pericellular matrix using alizarin red S (ARS) is described. Fresh blocks of epiphyseal cartilage approximately 1 mm thick were immersed into 0.5-2% ARS solution containing 7% mounted on glass slides in 7% sucrose or in glycerol-gelatin. The stained tissue blocks were also dehydrated in acetone, cleared in xylene and mounted in Preservaslide. The ARS precipitated ionic calcium as red Ca-ARS salt which was birefringent in polarizing microscope, stable in water at pH 4-9 and in nonpolar organic solvent but soluble in polar solvents, especially in dimethyl sulfoxide. In contrast, ARS-stained insoluble calcium phosphate was stable even in dimethyl sulfoxide. Calcium in the hypertrophied chondrocytes, therefore, was thought to be present in a readily ionizable state instead of as insoluble calcium phosphate. Since addition of 7% sucrose retained as well as improved ARS localization of cellular calcium, the calcium was believed to be present in an osmotically sensitive, membrane-bound cytoplasmic compartment. The ARS-positive labile calcium in spherules which develop in the hypertrophied chondrocytes as well as in the pericellular matrix at the zone of provisional calcification suggested a preparatory stage in the process of cartilage calcification.

Animals↗
PubMed1975

Calcium localized in juxtanuclear granules of epiphyseal chondrocytes with a dilute glyoxal bis(2-hydroxyanil) solution.

The glyoxal bis(2-hydroxyanil) (GBHA) method for staining labile calcium deposits in chondrocytes was modified. Fresh blocks of epiphyseal cartilage stained in this dilute GBHA solution revealed calcium in the juxtanuclear Golgi vesicles, each approximately 1 mu in diameter. Prolonged staining revealed previously described 0.5 mu granules throughout the cytoplasm which tended to mask the juxtanuclear reaction. The red GBHA reaction product was believed to be a chelate of calcium since it was removable with EGTA, and stable in Na2CO3 and KCN solution. When the tissue blocks stained with the dilute GBHA solution were restained with the original concentrated GBHA solution, refractile bodies containing red GBHA-positive granules were revealed at the periphery of the hypertrophied chondrocytes. The presence of calcium in the juxtanuclear Golgi vesicles and in the pericellular refractile bodies may indicate that the Golgi is involved in the transport of minerals to the matrix.

Aminophenols↗
PubMed1975

Chondroitin sulfate and electron lucent bodies in the pericellular rim about unshrunken hypertrophied chondrocytes of chick long bone.

Direct observation of unstained, 1 mm thick blocks of fresh epiphyseal cartilage from tibia of 15- and 18-day-old chick embryos revealed shrunken chondrocytes on its cut surfaces but unshrunken chondrocytes deep within the tissue blocks. The unshrunken hypertrophied chondrocytes are rimmed with refractile substance identified as chondroitin sulfate removable with hyaluronidase. This substance is stained metachromatically red with toluidine blue, and is stained with ruthenium red and with ruthenium red-OsO4. The latter, observed with the electron microscope, is present as an electron dense rim, specifically about the unshrunken, hypertrophied chondrocytes between the plasma membrane and lacunar wall. By rendering the chondroitin sulfate electron dense with RR-OsO4, electron lucent bodies (ELB) were revealed specifically about the hypertrophied chondrocytes. The ELB contain an electron dense core with radiating fibrils. The content and source of ELB, also found in the intercellular matrix, are not known. The 0.1% toluidine blue solution containing 0.2 M MgC12 or 0.4% NaCl or KCl stained juxtanuclear clusters of granules metachromatically red. The location of intracellular granules was believed to represent a cluster of Golgi-derived vesicles. The pericellular metachromatic, RR-OsO4-positive rim is believed to be an accumulation of externalized juxtanuclear metachromatic granules. The possibility that the ELB may also be externalized content of Golgi vesicles was entertained.

Animals↗