Microtubular response to colchicine in adult and fetal rat hepatocytes

1. Colchicine and related anti-microtubular drugs impair plasma protein secretion from adult rat liver explants 2-3-fold more than from fetal tissue. 2. Indirect immunofluorescence microscopy of cultured adult and fetal hepatocytes demonstrated that hepatocytes of both ages contain large numbers of densely packed microtubules which are equally disassembled by 10 microM colchicine. 3. Colchicine (10 microM) reduced secretion of [14C]leucine-labelled proteins from cultured adult hepatocytes by about 50% but did not significantly impede fetal secretion. 4. These results confirmed that plasma protein secretion can proceed without an intact microtubular system in fetal hepatocytes.

Radiological evaluation of hepatic artery aneurysms

The authors report 4 cases of hepatic artery aneurysm confirmed by computed tomography, sonography, angiography, and/or surgery. Three aneurysms involved the right hepatic artery and 1 involved the common hepatic artery. Two cases were treated with surgery, and the other 2 cases with transcatheter embolization. The clinical and radiological features of this entity are described together with a review of the pertinent literature.

Interaction of glyceraldehyde-3-phosphate dehydrogenase with AMP as studied by means of a spin-labeled analog

The binding of a spin-labeled AMP analog to tetrameric glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle is described. The spin label, perdeuterated and 15N-substituted 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, was attached to C-8 of AMP (C8-SL-AMP). Up to 8 equivalents of C8-SL-AMP bind per enzyme tetramer, i.e., 2 per monomer. Combining sites are the adenine subsite of the coenzyme-binding domain and the phosphate site. Glyceraldehyde 3-phosphate causes a conformational change in the enzyme that brings C8-SL-AMP molecules bound to adjacent R-axis-related subunits closer to one another by 0.2-0.3 nm and allows for spin-spin interaction between the nitroxide radicals. Similar, but less pronounced structural changes take place upon lowering the pH from 8 to 7. Addition of a single equivalent of NAD+ to a complex of the enzyme with 7.6 equivalents of C8-SL-AMP leads to the release of almost 4 C8-SL-AMP molecules. This supports our previous findings that binding of just one NAD+ molecule induces conformational changes in all four subunits.

Takayasu arteritis: angiographic findings and results of angioplasty

Takayasu arteritis is a systemic disease characterized by occlusion of the aorta and its branches. We performed coronary angiography and thoracic and abdominal aortography on 47 patients with Takayasu arteritis. Angiographic findings included arterial stenosis, occlusion, or aneurysm. The left subclavian artery was involved in 26 cases (55%), the abdominal aorta in 25 cases (53%), the right renal artery in 21 cases (45%), the right subclavian and left renal arteries in 18 cases (38%), the descending thoracic aorta in 15 cases (32%), and the left common carotid artery in 14 cases (30%). The coronary arteriograms in the 47 patients showed coronary involvement in seven (15%). Proximal or osteal lesions were present in six cases. Percutaneous transluminal angioplasty was performed successfully in eight patients for treatment of three aortic lesions, nine renal artery lesions, one subclavian artery lesion, and one coronary artery lesion. In the three cases with recurrence after 4-7 months, repeated angioplasty was successful. For appropriate management of Takayasu arteritis, we suggest thorough angiographic evaluation and proper intervention, including percutaneous transluminal angioplasty in selected cases for revascularization.

Small hepatocellular carcinoma: detection with sonography, computed tomography (CT), angiography and Lipiodol-CT

Seventy-three small hepatocellular carcinomas under 5 cm in diameter in 47 patients were examined by sonography, computed tomography (CT), hepatic angiography and CT after intra-arterial injection of iodized poppy-seed oil (Lipiodol-CT). The imaging techniques that first led to detection of small hepatocellular carcinomas were sonography in 53 cases (72.6%), CT in 10 (13.7%), angiography in eight (11%) and Lipiodol-CT in two (2.7%). Sensitivity for detecting small hepatocellular carcinomas was 73% with sonography, 82% with CT, 86% with angiography and 96% with Lipiodol-CT. As a screening method, sonographic and CT results in detecting small hepatocellular carcinomas were not significantly different (p greater than 0.05). Lipiodol-CT was superior to sonography (p less than 0.01), CT (p less than 0.01) and angiography (p less than 0.05) in detecting small hepatocellular carcinomas. We believe that the combined use of Lipiodol-CT with screening methods such as sonography or CT is indispensable for the accurate detection of small hepatocellular carcinomas.

Catalytic mechanism and interactions of NAD+ with glyceraldehyde-3-phosphate dehydrogenase: correlation of EPR data and enzymatic studies

Perdeuterated spin label (DSL) analogs of NAD+, with the spin label attached at either the C8 or N6 position of the adenine ring, have been employed in an EPR investigation of models for negative cooperativity binding to tetrameric glyceraldehyde-3-phosphate dehydrogenase and conformational changes of the DSL-NAD+-enzyme complex during the catalytic reaction. C8-DSL-NAD+ and N6-DSL-NAD+ showed 80 and 45% of the activity of the native NAD+, respectively. Therefore, these spin-labeled compounds are very efficacious for investigations of the motional dynamics and catalytic mechanism of this dehydrogenase. Perdeuterated spin labels enhanced spectral sensitivity and resolution thereby enabling the simultaneous detection of spin-labeled NAD+ in three conditions: (1) DSL-NAD+ freely tumbling in the presence of, but not bound to, glyceraldehyde-3-phosphate dehydrogenase, (2) DSL-NAD+ tightly bound to enzyme subunits remote (58 A) from other NAD+ binding sites, and (3) DSL-NAD+ bound to adjacent monomers and exhibiting electron dipolar interactions (8-9 A or 12-13 A, depending on the analog). Determinations of relative amounts of DSL-NAD+ in these three environments and measurements of the binding constants, K1-K4, permitted characterization of the mathematical model describing the negative cooperativity in the binding of four NAD+ to glyceraldehyde-3-phosphate dehydrogenase. For enzyme crystallized from rabbit muscle, EPR results were found to be consistent with the ligand-induced sequential model and inconsistent with the pre-existing asymmetry models. The electron dipolar interaction observed between spin labels bound to two adjacent glyceraldehyde-3-phosphate dehydrogenase monomers (8-9 or 12-13 A) related by the R-axis provided a sensitive probe of conformational changes of the enzyme-DSL-NAD+ complex. When glyceraldehyde-3-phosphate was covalently bound to the active site cysteine-149, an increase in electron dipolar interaction was observed. This increase was consistent with a closer approximation of spin labels produced by steric interactions between the phosphoglyceryl residue and DSL-NAD+. Coenzyme reduction (DSL-NADH) or inactivation of the dehydrogenase by carboxymethylation of the active site cysteine-149 did not produce changes in the dipolar interactions or spatial separation of the spin labels attached to the adenine moiety of the NAD+. However, coenzyme reduction or carboxymethylation did alter the stoichiometry of binding and caused the release of approximately one loosely bound DSL-NAD+ from the enzyme. These findings suggest that ionic charge interactions are important in coenzyme binding at the active site.

Giant cavernous hemangioma of the liver: CT and MR imaging in 10 cases

Ten giant cavernous hemangiomas of the liver in eight patients were examined with both MR imaging and dynamic bolus CT. The maximal diameters of the tumors were 6.5-19 cm (mean, 10.8 cm). MR imaging was done with a 2.0-T superconducting magnet and spin-echo imaging. CT was done with single-bolus dynamic scans. On MR images, all 10 hemangiomas had a heterogeneous appearance. The main part of the tumor comprised uniform, well-defined, high-intensity areas on T2-weighted images, with increasing intensity ratios with prolongation of TR and TE. Other parts of the tumor were cleftlike and were of lower intensity than the remainder of the tumor on T1-weighted images and of higher intensity on heavily T2-weighted images. These parts corresponded to the areas of the tumor that were of lower density on dynamic bolus CT scans. Internal septa in the tumor of low intensity were also noted on all MR pulse sequences. These parts corresponded to low-density areas on delayed contrast-enhanced CT. Familiarity with the characteristics of the internal architecture of giant cavernous hemangiomas on MR imaging or dynamic bolus CT might be useful in making the correct diagnosis of this tumor.

Microcholangiography. Normal microbiliary system and its alteration after extrahepatic bile duct obstruction

The authors used microcholangiography to demonstrate the feasibility of the technique and the features of the normal and the obstructed biliary systems. Furthermore, they attempted to explain the pathophysiology of cholangiography-related septicemia with this technique. Extrahepatic bile ducts (EHBD) of 40 rabbits were ligated, and microcholangiography was carried out with infusion of barium suspension immediately as well as one, three, and five days after ligation. Microradiographic technique was used and the findings were correlated with histopathologic features. The intrahepatic microbiliary system such as interlobular bile ducts and ductules were well visualized. After EHBD ligation, ductules were tortuously dilated. The histologically observed ductular proliferation in many hepatobiliary diseases could be attributed in part to the tortuosity of bile ductules, particularly when biliary obstruction is present. Regurgitation of barium into hepatic sinusoids was demonstrated in 36 rabbits (90%) and probably was caused by rupture of interlobular bile ducts and ductules.

Expression of cloned rpoB gene of Escherichia coli: a genetic system for the isolation of dominant negative mutations and overproduction of defective beta subunit of RNA polymerase

The rifampin resistance rifD18 allele of rpoB, carried on the expression plasmid pXT7 beta, is controlled by a strong bacteriophage T7 late promoter and two weak Escherichia coli promoters. Depending on the host strain, pXT7 beta specifies different levels of Rifr beta subunit, providing a system for the isolation, maintenance, and overexpression of dominant lethal alleles of rpoB. In rpoB+ hosts, pXT7 beta confers the Rifr phenotype on the Rifs host. Negative rpoB mutations in the plasmid DNA can thus be scored by screening transformants for Rifs. In an rpoB(Am) supD(Ts) host in which chromosomal rpoB expression is decreased as the temperature goes up, some of the negative plasmid-borne rpoB mutations displayed a dominant phenotype. In a host harboring inducible T7 RNA polymerase, the defective beta subunits could be overexpressed independently of the E. coli transcriptional machinery. With this system, we isolated several negative rpoB mutations induced in vitro by hydroxylamine. Seven of the mutant rpoB alleles, when overexpressed, were found to specify normal-size beta polypeptides. Two of them displayed the dominant lethal phenotype in the rpoB(Am) supD(Ts) background. We also constructed a mutation (rpoB1800) in which 24 carboxy-terminal amino acids were substituted with a random 19-amino-acid sequence. The nonfunctional rpoB1800 beta polypeptide was isolated and assembled in vitro into the core enzyme molecule.

Suppression of diamine oxidase activity enhances postresection ileal proliferation in the rat

To assess the influence of diamine oxidase activity on the adaptive process of the small bowel after resection, we administered aminoguanidine, a potent diamine oxidase inhibitor, to rats for 10 days after either small bowel transection (n = 5) or 80% jejunoileal resection (n = 7). Five or more additional animals from each group received saline as controls. Ileal mucosal homogenates from the resection group receiving aminoguanidine, when compared with those from resection controls, showed no diamine oxidase activity with increased putrescine content and ornithine decarboxylase activity. Mucosal proliferation, as measured by mucosal mass, protein content, and deoxyribonucleic acid content, was greater in the resected animals receiving aminoguanidine when compared with that of resection controls. Sucrase activity per gram of mucosa was almost identical in both resection groups. These results show that the suppression of diamine oxidase during the postresection adaptive period results in enhanced mucosal proliferation with no effect on mucosal functional differentiation. Diamine oxidase may play a regulatory role in adaptive intestinal proliferation.

Effects of dietary linoleic acid on mucosal adaptation after small bowel resection

We have shown that dietary long-chain triglycerides and 16,16-dimethyl prostaglandin E2 enhance and aspirin impairs postresection mucosal adaptation in rats. The present studies examined the hypothesis that supplemental linoleic acid (LA) above the minimum requirement may enhance postresection mucosal adaptation through altered prostaglandin (PG) synthesis. Forty male Sprague-Dawley rats (105 +/- 5 g) were fed purified diet containing either 5% LA or 4% palmitic acid and 1% LA. After 2 weeks, 12 rats from each dietary group underwent 70% proximal jejunoileal resection and the remainder were sham-operated. Dietary regimens were continued for an additional 13 days. Mucosal fatty acid analysis of 1% LA group revealed a ratio of 20:3 n-9/20:4 n-6 lower than 0.2, indicating normal essential fatty acid status. Mucosal protein per centimeter bowel was higher in the 5% LA group compared to the 1% group, but mucosal DNA, maltase, and ex vivo PG synthesis were not affected. These results indicate that LA stimulates postresection mucosal hypertrophy, which does not appear to be related to PG synthesis.

Energy metabolism of the untrained muscle of elite runners as observed by 31P magnetic resonance spectroscopy: evidence suggesting a genetic endowment for endurance exercise

The purpose of this study was to investigate whether genetically determined properties of muscle metabolism contribute to the exceptional physical endurance of world-class distance runners. ATP, phosphocreatine, inorganic phosphate, and pH were quantitatively determined by 31P nuclear magnetic resonance spectroscopy in the wrist flexor muscles of elite long-distance runners and sedentary control subjects. These muscles had not been exposed to any specific program of exercise training in either group of subjects. The "untrained" muscles were examined at rest, during two cycles of three grades of exercise, and in recovery. The flexor muscles of the athletes had higher concentrations of phosphocreatine and ATP than did those of the control subjects at rest and during exercise. The athletes' muscles possessed a higher capacity for generation of ATP by oxidative metabolism than did control subjects' muscles according to the following criteria: (i) high force output, 60% of maximum voluntary contraction, was more easily reached and better maintained in both exercise cycles; (ii) the ratio of inorganic phosphate to phosphocreatine rose less during exercise and recovered faster in the postexercise period; (iii) there was no loss of adenine nucleotides or total phosphate from the athletes' muscles but significant losses from the control subjects' muscles; and (iv) the pH decreased no more than 0.1 unit in the athletes' muscles during exercise, attesting to a relatively slow glycolysis and/or a rapid oxidation of lactate. In the muscles of the control subjects, on the other hand, the pH decreased nearly 0.4 unit early in the first exercise cycle, indicating a relatively fast glycolysis and/or slower oxidation of lactate. In the second exercise cycle, the pH returned to near normal in the control subjects' muscles, reflecting diminished lactate formation because of glycogen depletion and lactate washout by the high blood flow induced by exercise. By the end of the exercise program, the maximum voluntary contractile force for the control subjects had declined to less than 60% of the initial value. This decline could be explained best by exhaustion of the glycolytic contribution to muscle contraction. Therefore, the residual maximum strength provided a measure of the oxidative capacity to support contraction, as is discussed. In conclusion, we suggest that a greater oxidative capacity relative to glycolytic capacity for support of contraction in untrained muscle of world-class runners reflects a genetic endowment for physical endurance. Additional systemic effects of training cannot be completely excluded. 31P magnetic resonance spectroscopy provides a noninvasive method for assessing this endowment.

Clinical investigation in Duchenne muscular dystrophy: penicillamine and vitamin E

A double-blind controlled trial of penicillamine and vitamin E against placebo was conducted in 106 boys with Duchenne muscular dystrophy. Nine dropped out of the study after being randomized. Patients were evaluated using an established protocol that measures muscle strength, joint contractures, functional grade, and pulmonary function. The trial lasted for 18 months. The power of the study to detect a 75% slowing of the disease was 0.95 at a P less than 0.05. No therapeutic effect was observed in the patients taking penicillamine and vitamin E as compared with those taking placebo.

Purification and Characterization of Thermostable Pullulanase from Bacillus stearothermophilus and Molecular Cloning and Expression of the Gene in Bacillus subtilis

A thermostable pullulanase (α-dextrin 6-glucanohydrolase [EC 3.2.1.41]) from a newly isolated Bacillus stearothermophilus strain (TRS128) was purified and characterized. The enzyme hydrolyzed (1→6)-α- d -glucosidic linkages of pullulan to produce maltotriose, and the optimum temperature was 65°C. About 90% of the enzyme activity was retained after treatment at 65°C for 60 min. By using pTB522 as a vector plasmid, the pullulanase gene was cloned and expressed in Bacillus subtilis.

Peripheral cholangiocarcinoma and clonorchiasis: CT findings

Sixteen patients with peripheral cholangiocarcinoma of the liver were examined with computed tomography (CT). None of the 16 patients presented with jaundice or had documented cirrhosis. On scans obtained both before and after the injection of contrast material, the tumors were depicted as low-attenuation masses in all cases, with wide variations in homogeneity. The tumor margin was irregular in 12 cases, and there was minimal contrast enhancement of the tumor in 14 cases. In 11 (69%) patients, CT demonstrated masses of markedly low attenuation, which corresponded to areas of diffuse microcystic change seen at histologic examination of resected specimens. In ten (63%) patients, the results of stool or intradermal tests for Clonorchis sinensis were positive. In all ten cases of clonorchiasis, mild, diffuse dilatation of the intrahepatic bile ducts was seen in addition to the low-attenuation masses, but there was no dilatation of the extrahepatic biliary tree. In five of the ten patients with clonorchiasis, stippled or aggregated, powderlike areas of high attenuation were seen on precontrast CT scans; at pathologic examination, those areas were found to be mucin. Extrahepatic metastases were demonstrated in ten (63%) patients. Peripheral cholangiocarcinoma should be the primary diagnostic consideration when these characteristic CT findings are detected in a noncirrhotic patient.

Infective endocarditis in a patient with Williams' syndrome--case report

An 18-year-old male was admitted to Seoul National University Hospital for the evaluation of fever and chill on February 3, 1988.

On physical examination, his face showed a characteristic “elfin” facial appearance. His face was characterized by abnormalities of dental development, a broad overhanging upper lip, high arched palate and gum hypertrophy. He also showed mental retardation.

Cardiac catheterization with selective cineangiocardiography demonstrated a supravalvular aortic narrowing, grade 2 aortic insufficiency, and moderately dilated proximal coronary arteries with normal distribution without an intraluminal narrowing. There was a systolic pressure gradient (55mmHg) between the aortic root and ascending aorta distal to a stenotic segment.

MRI showed a supravalvular aortic stenosis.

Vegetation was not found on echocardiograpghy. Unidentified G(−) rods were isolated in 3 out of 9 bottles in blood culture test.

He was treated with Na-penicillin and gentamicin for 28 days.

Analysis of signals controlling expression of the Chinese hamster ovary aprt gene

The 5' end of the Chinese hamster ovary aprt gene was sequenced and transcription start sites were determined by both S1 nuclease protection and primer extension assays. Deletion mutants covering the same area were constructed, and adenine phosphoribosyltransferase (APRT) or chloramphenicol acetyltransferase (CAT) activity was measured by transient-expression assays. The aprt gene uses a single cluster of transcription start sites and lacks consensus sequences such as TATA and CCAAT, which are general components of eucaryotic promoters. The 5' deletion mutations of the promoter sequences demonstrated that (i) there is no decrease in either APRT activity or transcription extending to position -89 (relative to the main transcription start site); (ii) an additional 29-base-pair (bp) deletion decreases APRT activity and transcription twofold; and (iii) a deletion past the transcription start sites (P5' delta +27) abolishes both APRT activity and transcription, indicating that a 60-bp fragment immediately upstream of the main transcription start site is involved in basic transcription and a 29-bp fragment just upstream of the 60 bp-fragment stimulates transcription twofold. The 3' deletion mutations showed that a deletion of a 61-bp fragment in the 5' leader and coding sequence abolishes the efficient translation of an aprt-CAT gene transcript. In addition, there are two polyadenylation signals at the genomic 3' end, with the proximal one being sufficient for functional polyadenylation.

Reduced mucosal prostaglandin synthesis after massive small bowel resection

Exogenous 16,16-di-methyl-prostaglandin (PG) E2 administration augments mucosal hyperplasia after massive small bowel resection in the rat. We, therefore, evaluated the ability of aspirin to inhibit mucosal PG synthesis in the small intestine and further evaluated the effects of reduced PG synthesis on mucosal adaptation after a 70% jejunoileal resection in male Sprague-Dawley rats. Sixteen of 27 resected and 8 of 16 sham-operated rats were given aspirin 20 mg/kg body wt subcutaneously every 8 h for 12 days; the remainder were given vehicle only. Although mucosal PGE2, PGF2 alpha, and thromboxane B2 synthesis were all reduced by aspirin administration to 20-40% of the control values, mucosal adaptation in resected animals as measured by mucosal weight, DNA, protein, and maltase levels was only inhibited in the distal ileum. Aspirin did not affect these values in the duodenum, the upper jejunum, and the midileum. This study provides evidence for some involvement of endogenous PGs in regulation of the mucosal adaptation process in the distal ileum after massive small bowel resection in the rat. However, lack of inhibition more proximally suggests that factors other than PGs are more important.

Essential fatty acid deficiency and postresection mucosal adaptation in the rat

The effect of short-term (biochemical) and long-term (clinical) essential fatty acid (EFA) deficiency on mucosal adaptation was studied in a surgical model of short bowel syndrome. Rats fed an EFA-deficient diet for 4 wk had biochemical evidence of EFA deficiency (hepatic and red blood cell triene to tetraene ratios greater than 0.4). Resected animals (70% proximal jejunoileal resection) receiving an EFA-deficient diet had a significantly impaired intestinal mucosal hyperplasia response in all remaining small bowel segments compared with resected controls. The effect of refeeding a control diet to clinically EFA-deficient resected rats was also evaluated. Short-term refeeding (2 wk) of a control diet resulted in a significant return toward normal tissue triene to tetraene ratios. Concomitantly, refed animals had significantly greater mucosal adaptation in the remaining duodenal/jejunal segment compared with resected animals maintained on an EFA-deficient diet postoperatively. These experiments underscore the dynamic nature of tissue EFA status and the importance of fatty acids in the normal compensatory mechanisms of mucosal adaptation after resection.

Purification and characterization of protease Re, a cytoplasmic endoprotease in Escherichia coli

Protease Re, a new cytoplasmic endoprotease in Escherichia coli, was purified to homogeneity by conventional procedures, using [3H]casein as the substrate. The enzyme consists of a single polypeptide of 82,000 molecular weight. It is maximally active between pH 7 and 8.5 and is independent of ATP. It has a pI of 6.8 and a Km of 10.8 microM for casein. Since diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride inhibited this enzyme, it appears to be a serine protease. Protease Re was sensitive to inhibition by L-1-tosylamido-2-phenylethylchloromethylketone but not to that by 1-chloro-3-tosylamido-7-aminoheptanone, thiol-blocking reagents, chelating agents, or various peptide aldehydes. Re also degraded [125I]globin, [125I]glucagon, and 125I-labeled denatured bovine serum albumin to acid-soluble products (generally oligopeptides of greater than 1,500 daltons), but it showed no activity against serum albumin, growth hormone, insulin, or a variety of fluorometric peptide substrates. It also hydrolyzed oxidatively inactivated glutamine synthetase (generated by ascorbate, oxygen, and iron) four- to fivefold more rapidly than the native protein. Protease Re appears to be identical to the proteolytic enzyme isolated by Roseman and Levine (J. Biol. Chem. 262:2101-2110, 1987) by its ability to degrade selectively oxidatively damaged glutamine synthetase in vivo. Its role in intracellular protein breakdown is uncertain.