Biomedical subjects
K Okuda
Publications and source records attributed to K Okuda.
Emergence of malignant lesions within an adenomatous hyperplastic nodule in a cirrhotic liver. Observations in five cases.
Five cases of an adenomatous hyperplastic nodule or a similar lesion resected from a cirrhotic liver in which early malignant foci were seen as small nodule-in-nodule lesions are described. These hyperplastic lesions were detected by imaging diagnosis in patients with nonalcoholic cirrhosis, mostly during routine clinical follow-up. In 2 patients, recurrence of hepatocellular carcinoma occurred 11 mo and 15 mo postresection. Thus, these nodule-in-nodule lesions in an adenomatous hyperplastic nodule seem to represent an early stage of hepatocarcinogenesis in humans. In nonalcoholic cirrhotic patients from Japan and Southeast Asia, in whom hepatocellular carcinoma is endemic, an adenomatous hyperplastic nodule or a similar hyperplastic lesion that occurs in cirrhotic livers may be preneoplastic and already committed to malignant transformation.
Transformation of inferior vena caval thrombosis to membranous obstruction in a patient with the lupus anticoagulant.
A 24-yr-old woman with hemolytic anemia developed multiple thrombosis of the hepatic vein and inferior vena cava. She was found to have circulating lupus anticoagulant that could have been causally related to the thrombosis and hence the Budd-Chiari syndrome. On her first admission to the hospital vena cava and hepatic vein catheterizations revealed partial thrombotic occlusion of the cava at the level of the diaphragm, which was subsequently transformed into complete membranous obstruction. The right hepatic vein, which was patent on the first admission, was also completely occluded. These observations support the theory that membranous obstruction of the inferior vena cava is a sequela to inferior vena caval thrombosis rather than a congenital anomaly.
Resolution of diffuse granulomatous fibrosis of the liver with antituberculous chemotherapy.
A 71-yr-old man with pulmonary tuberculosis developed jaundice, and an ultrasound examination suggested hepatolithiasis. The liver was markedly enlarged and of stony consistency. Two 2.5-cm biopsy specimens of the liver each disclosed diffuse fibrosis with giant cells; practically no normal parenchyma was seen. Ultrasonography and computed tomography disclosed multiple intrahepatic calcifications, and percutaneous cholangiography revealed stenosis of the right hepatic duct. One year after treatment with antituberculous drugs, liver biopsy specimens taken from the same areas of the liver showed nearly normal histology.
Foscarnet decreases serum and liver duck hepatitis B virus DNA in chronically infected ducks.
Foscarnet (trisodium phosphonoformate) is a new antiviral compound with in vitro inhibitory effects against the DNA polymerases of hepadna viruses. To study the effects of the drug in chronic hepadna virus infection, we treated ducks chronically infected with duck hepatitis B virus for 10 days with either low-dose foscarnet (50 mg/kg i.p. b.i.d.), high-dose foscarnet (250 mg/kg i.p. b.i.d.), or sterile water injections. Serum duck hepatitis B virus DNA and intrahepatic replicative forms of the virus were measured using molecular biological techniques with both a double-stranded radiolabeled DNA probe and a plus-strand (noncoding) specific RNA probe. We found a dose-related decrease in serum and intrahepatic duck hepatitis B virus DNA during treatment, with a rapid return toward baseline values after the cessation of treatment. There was a disproportionate decrease in the plus strand of viral DNA with treatment. We conclude that foscarnet exerts its effect in hepadna virus infection through inhibition of viral DNA polymerase. Further study is necessary to determine whether foscarnet, by itself or in combination with other treatment modalities, has a role to play in the treatment of chronic hepatitis B infections in humans.
Natural history of minute hepatocellular carcinoma smaller than three centimeters complicating cirrhosis. A study in 22 patients.
Twenty-two patients with cirrhosis and minute hepatocellular carcinoma less than 3 cm in diameter were followed for periods of 6-37 mo without specific treatment. The survival curve drawn by the Kaplan-Meier method showed a 1-yr survival of 90.7%, a 2-yr survival of 55.0%, and a 3-yr survival of 12.8%. The ultrasonic patterns of these masses in the liver were correlated with the size and showed a tendency to change from a low echo pattern to a low periphery and, finally, to a massive pattern. The growth speed calculated from the doubling time for tumor volume varied considerably from case to case with an average of 6.5 +/- 5.7 mo; it also changed in some cases during the observation period. Serum alpha-fetoprotein levels were generally low, rarely assisted in diagnosis, but tended to increase when the mass attained a diameter of greater than 3 cm; sudden acceleration in the rate of increase in alpha-fetoprotein level often coincided with a change of ultrasonic pattern to the massive one.
Study on the appearance of the cavity in the corpus luteum of cows by using ultrasonic scanning.
A transrectal real-time B mode linear scanner was used to learn if the appearance of a cavity in the corpus luteum (CL) in cows causes infertility. Sixty-one cows that were confirmed to have ovulated after artificial insemination (AI) were used. Some of the cows that returned to estrus were examined two or three times; thus, a total of 78 observations were made. The rate of cavity appearance was 37.2% (29 78 ). In relation to the size of cavity, the rates of appearance were 30.8% of CL with cavities of 7 mm or greater and 24.4% with cavities of 10 mm or greater in diameter. It took more than 21 days for the cavity more than 10 mm to disappear. In the cows that were observed two or three times, the cavity did not tend to reappear. The mean period for return to estrus, mean serum progesterone concentration and mean pregnancy rate were not significantly different (P>0.05) for cows that had CL with or without a cavity. Our results suggest that the cavity mentioned above does not cause infertility.
Experimental gold nephropathy in guinea pigs: detection of autoantibodies to renal tubular antigens.
Renal tubular dysfunction was induced in Hartley guinea pigs by injection of sodium aurothiomalate (gold) as manifested by excretion of tubular basement membrane (TBM) antigen and renal tubular epithelial (RTE) antigen in urine and tubular proteinuria. Following the tubular dysfunction, autoimmune tubulointerstitial nephritis (TIN) and/or immune complex nephropathy (ICN) developed in a large proportion of animals. TIN was associated with anti-TBM antibodies, and the histological features were characterized by tubular lesions with interstitial mononuclear cell infiltration, destruction of tubules, and interstitial fibrosis. In ICN, the glomerular lesions consisted of partial thickening of capillary walls and mesangial cellularity, and granular immune deposits were seen in the mesangial area and on capillary walls. Furthermore, electron-dense deposits were demonstrated in the mesangial area and in the glomerular basement membrane (GBM) by electron microscopy. Anti-RTE antibodies were detected in the sera and eluates from the kidney of animals with ICN. RTE antigens were also detected in the glomerular deposits by indirect immunofluorescence using anti-guinea pig RTE antibody. These results suggest that TBM and RTE antigens released from renal tubules damaged by a direct toxic action of gold may lead to antibody formation against these antigens and induce TIN and/or ICN.
Two types of immunoglobulin-negative Abelson murine leukemia virus-transformed cells: implications for B-lymphocyte differentiation.
Both alleles of immunoglobulin (Ig) heavy-chain joining region (JH) genes in three Ig-negative Abelson murine leukemia virus (Ab-MuLV)-transformed cell lines were characterized by DNA cloning and nucleotide sequence determination. These studies unambiguously identified two distinct types of Ig-negative B-lineage cells. The first type of cell (e.g., R8) is an "immature pre-B cell," and it contains at least one intermediate recombinant structure containing heavy-chain diversity (DH) and JH sequences but no variable region (VH) sequence. This type of cell, which has also been characterized by other investigators, generates mu-positive sublines during subsequent culturing of cells and represents a precursor stage to pre-B cells. The second type of cell (e.g., RAW253) is an "abortive pre-B cell," in that both JH alleles contain nonfunctional VH-DH-JH structures. The nucleotide sequence determinations in this study demonstrated that these nonfunctional V-D-J structures were generated by nonproductive somatic recombinations, involving either out-of-phase joining events, or the formation of termination codons in the DH coding sequences. The identification of abortive pre-B cells suggests that the recombinational joining of Ig VH, DH, and JH segments is not actively regulated by a putative recombinase to preserve the translational reading frame. This in turn implies that a large portion of precursor cells at the early stage of B-cell differentiation are abortive and possibly blocked to further differentiation.
Isolation of a cytochrome P-450 that catalyzes the 25-hydroxylation of vitamin D3 from rat liver microsomes.
A molecular species of cytochrome P-450 that catalyzes the 25-hydroxylation of cholecalciferol (P-450cc25) was purified from rat liver microsomes on the basis of its catalytic activity. The purification procedure consisted of polyethylene glycol fractionation, and column chromatographies on octylamino Sepharose 4B, hydroxylapatite, DEAE-Sepharose CL-6B, and CM-Sepharose CL-6B. The specific cytochrome P-450 content of the final preparation was 17.0 nmol/mg of protein. The enzymatic activity was reconstituted with the purified cytochrome P-450, NADPH-cytochrome P-450 reductase, an NADPH-generating system, and dilauroylglyceryl-3-phosphorylcholine, the specific activity obtained being 3.7 nmol/min/mg of protein, which was 4,000 times as high as that in microsomes. The apparent molecular weight of the P-450cc25 was 50,000, based on the results of sodium dodecyl sulfate polyacrylamide gel electrophoresis. The absorption spectra of the oxidized form of the enzyme showed a Soret band at 416 nm, which is typical of the low spin state of cytochrome P-450, and alpha and beta bands at 570 and 536 nm, respectively. The Soret peak of the reduced cytochrome P-450-CO complex was at 450 nm. The purified enzyme not only catalyzed the 25-hydroxylation of cholecalciferol but also showed hydroxylation activity toward a variety of substrates, i.e. 1 alpha-hydroxycholecalciferol (at 25), testosterone (at 2 alpha and 16 alpha) and dehydroepiandrosterone (at 16 alpha). Amino terminal sequence of the purified cytochrome P-450 was determined by the manual sequence method to be H2N-Met-Asp-Pro-Val-leu-Val-Leu-Val-. The antibody elicited against the purified enzyme in a rabbit inhibited the cholecalciferol 25-hydroxylation activity by more than 90% with a concentration of 2 mg of immunoglobulin per nmol of cytochrome P-450.
Serum cholinesterase in patients with fatty liver.
In search of a practical biochemical test that will reflect hepatic steatosis, we assessed the significance of serum cholinesterase activity in 48 patients with nonalcoholic fatty liver, 16 obese subjects without fatty liver, 30 cases of chronic persistent hepatitis, 38 cases of chronic active hepatitis, and 20 cases of liver cirrhosis. Increased cholinesterase activity was observed in nonobese as well as obese patients with fatty liver, whereas obese subjects without fatty liver showed levels in the upper normal range. When we set a cutoff level above the upper normal limit, half of the patients with fatty liver showed values above it, with only a few overlaps with other patients. When obese patients with fatty liver took a low-caloric diet, cholinesterase activity decreased, clearly reflecting improvement of hepatic steatosis. Thus, measurement of cholinesterase activity is of diagnostic value and an alternative to computed tomography in hepatic steatosis, and will provide a practical measure for the assessment of effects during follow-up.
Synthetic Salmonella-type lipid A antigen with high serological specificity.
A synthetic compound (compound 516), beta(1-6)-linked D-glucosamine disaccharide 1,4'-bisphosphate, which is acylated by (R)-3-hexadecanoyloxytetradecanoyl, (R)-3-hydroxytetradecanoyl, (R)-3-dodecanoyloxytetradecanoyl, and (R)-3-tetradecanoyloxytetradecanoyl groups at positions 2,3,2', and 3', respectively, exhibited in vitro antigenic reactivity of high specificity comparable to that of free lipid A from Salmonella minnesota R595. This was confirmed by an enzyme-linked immunosorbent assay and an enzyme-linked immunosorbent assay inhibition test with monoclonal and conventional antibodies. The results of comparative analysis performed with several synthetic lipid A analogs as well as three monosaccharide derivatives suggested that the complete structure involving both phosphate groups at the C-1 and C-4' positions and the 3-acyloxyacyl groups at the C-2, C-2', and C-3' positions of the glucosamine disaccharide are required for the expression of the serological specificity of Salmonella-type lipid A. This was deduced from the observations that compound 506, a synthetic Escherichia coli-type lipid A which has the same structure as that of compound 516, except that 3-hydroxytetradecanoyl group is substituted for an acyloxyacyl residue at the C-2 position, exhibited significantly reduced antigenic reactivity as compared with compound 516 and that the replacement by the hydrogen atom of the phosphoryl group at the C-1 position or by 3-hydroxytetradecanoyl or tetradecanoyl groups of acyl residues at the 2, 3, 2', and 3' positions of compound 516 results in a marked reduction of reactivity with monoclonal antibodies 5G and 36G. Similar results were obtained by assays with conventional rabbit antibodies, but the structural difference between compounds 516 and 506 could not be distinguished by these polyclonal antibodies. The results of cross-reactions among synthetic analogs with monoclonal antibodies 161M and 1-9M, which have been confirmed to exhibit different serological specificities from the 5G or 36G antibody, also suggested that the nature and linkage of fatty acyl residues as well as the backbone structure of lipid A play an important role in determining serological specificity of the lipid A molecule.
Purification and properties of hemagglutinin from culture supernatant of Bacteroides gingivalis.
The hemagglutinating factor (hemagglutinin) of Bacteroides gingivalis was prepared from the supernatant of a 5-day diffusate broth culture by ammonium sulfate precipitation and column chromatography with a hydrophobic column of Phenyl-Sepharose CL-4B, DEAE-Sephadex A-50, and Sephadex G-100 gel filtration. The hemagglutinating activity of the preparation was 53.3 times higher than that of ammonium sulfate precipitate. In electron microphotographs, hemagglutinin appears to have a vesicle or tubelike structure. The hemagglutinating activity of intact cells was completely destroyed by heating at 100 degrees C for 10 min, but the activity of extracted hemagglutinin was heat stable. The activity of hemagglutinin was inhibited by L-arginine and L-lysine and partially inhibited by phospholipase D, but it was not affected by proteolytic enzymes, neuraminidase, hyaluronidase, lipase, phospholipase A and C, or sugars. The B. gingivalis hemagglutinin appeared to be comprised mainly of a 40,000-molecular-weight material. The Fab fragment of immunoglobulin G prepared from rabbit antiserum to whole cells of B. gingivalis and monoclonal antibody against the hemagglutinin bound to the cell surface and inhibited the hemagglutinating activity of both the cells and the purified hemagglutinin.
Antigenic characteristics and serological identification of 10 black-pigmented Bacteroides species.
Strains of 10 black-pigmented Bacteroides species were serologically characterized using absorbed and unabsorbed rabbit antisera. An agglutination test using intact cells or heated cells (100 degrees C for 60 min) from each species and unabsorbed antisera revealed only homologous reactions with little or no reactivity in heterologous assays. Immunodiffusion tests using sonicated antigen demonstrated that Bacteroides gingivalis, B. endodontalis, B. asaccharolyticus, B. macacae, and B. levii are antigenically distinct. Strains of B. gingivalis, B. endodontalis, and B. asaccharolyticus were also clearly identified by the indirect immunofluorescent antibody method. B. intermedius, B. corporis, B. loescheii, B. melaninogenicus, and B. denticola possessed common antigens; however, species-specific antigens detectable with immunoabsorbed antisera were also demonstrated. B. intermedius strains isolated from the human oral cavity included at least two serogroups. In each black-pigmented Bacteroides species, lipopolysaccharide constituted one of the species-specific antigens.
Precipitating antibody against lipopolysaccharide of Haemophilus actinomycetemcomitans in human serum.
Approximately 6% of 50 tested human sera possessed precipitating antibody against lipopolysaccharide from Haemophilus actinomycetemcomitans (Actinobacillus actinomycetemcomitans).
Diagnosis of small hepatocellular carcinoma: correlation of MR imaging and tumor histologic studies.
Magnetic resonance (MR) images of the liver were used to study 43 patients with relatively small hepatocellular carcinomas (HCCs) and 36 with other hepatic mass lesions. In 27 HCC patients, histologic findings were available. All focal lesions detectable by CT without contrast media were delineated with greater contrast by MR imaging. The rate of detection depended on tumor size, being 97.5% for HCCs greater than 2 cm in the longest axis and 33.3% for those less than 2 cm. MR imaging demonstrated the ring sign characteristic of encapsulated HCC twice as frequently as CT scans. Inversion recovery (IR) images depicted the internal structure of the HCC better than T2-weighted spin-echo images. Lesions were classified into four patterns of intensity: low, iso, high, and mixed. The latter three were relatively characteristic of HCC and related closely with steatosis of cancer tissue. HCCs with fibrosis tended to have long T1 values; those with steatosis had short T1 values. T1 and T2 relaxation times were useful in the differential diagnosis.
Aryl hydrocarbon hydroxylase activity in rat submandibular glands.
The activities of aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-de-ethylase in the rat submandibular gland, both of which are normally very low, were increased about 10- and 25-fold, respectively, by administration of 3-methylcholanthrene. The increased activity of aryl hydrocarbon hydroxylase was inhibited by 7,8-benzoflavone but little if any by metyrapone and SKF-525A. The submandibular gland aryl hydrocarbon hydroxylase was also inhibited by antibodies elicited against rat liver cytochrome P-448 and NADPH-cytochrome P-450 reductase, respectively, and slightly by anti-cytochrome b 5 antibody, suggesting that submandibular gland aryl hydrocarbon hydroxylase resembles that of the liver, not only in the immunochemical properties of cytochrome P-450 involved, but also in the entire enzyme complex, including the electron transferring system. Cofactor(s) required by aryl hydrocarbon hydroxylase in submandibular gland was NADPH, whereas NADH sustained the reaction at a much slower rate (about 20%). NADH showed some additive action when added with NADPH.
Susceptibility of Bacteroides gingivalis to bactericidal activity of human serum.
Susceptibility of Bacteroides gingivalis strains to the complement-mediated bactericidal activity of human serum was examined under anaerobic conditions. Serum containing high concentrations of IgG antibody to B. gingivalis enhanced the bactericidal activity. No enhancement was found in serum which did not contain the specific antibody or in serum absorbed with intact cells. The sensitivity to the killing by pooled serum differed among B. gingivalis strains. Cells of B. gingivalis activated the pooled human serum complement not only through the classic pathway but also through an alternative pathway. It was found that the susceptibility of B. gingivalis to the bactericidal activity was classic-pathway-dependent.