Tyramine oxidase activity in needle biopsy of normal livers and diseased livers.

Tyramine oxidase and UDP-glucuronyl transferase activities were determined in 52 diseased livers obtained by needle biopsy. 14 liver specimens were also subjected to acetyl CoA carboxylase determination. Tyramine oxidase level was elevated in livers with nonalcoholic fatty change or toxic hepatitis, and reduced in livers with fibrosis or chronic alcoholic injury. UDP-glucuronyl transferase activity was reduced in livers with severe parenchymal damage or hyperbilirubinemia. Acetyl CoA carboxylase activity decreased markedly in an active alcoholic cirrhotic liver, and was elevated in alcoholic fatty livers as well as in a liver with acute venous stasis.     

Human livers with cirrhosis and hepatocellular carcinoma have less mitochondrial DNA deletion than normal human livers.

We measured the populations of mutated mitochondrial DNAs with the 7,436 bp or the 4,977 bp deletion from apparently normal human liver and human livers with chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The amount of the mutated mitochondrial DNA was at the same level between normal and chronically hepatitic livers but was significantly lower in human livers with cirrhosis and hepatocellular carcinoma, especially the latter, suggesting that the mutated mitochondrial DNAs may be decreased with the progress of liver disease from chronic hepatitis to cirrhosis and hepatocellular carcinoma. This phenomenon is opposite to that occuring in the ageing process.     

Use of texture analysis to discriminate between normal livers and livers with steatosis

We describe a technique for discriminating between livers that are normal and ones that have fatty infiltrate (livers with steatosis) based upon the application of a suitably defined texture measure to the corresponding digitized ultrasonographs. In brief, this texture measure sums, from some selected optimum spatial frequency to the upper limit set by the digitizing process, the frequency components of the normalized, radial power spectral density function. The analysis was run on six cases (two normal and four with steatosis) obtained from Dunedin Public Hospital, in New Zealand. Texture measure values for these six cases were compared with the corresponding biopsy scores. The results indicate the ability of the texture measure to discriminate between the two conditions; and furthermore, to quantitatively distinguish the severity of histological change.     

Microbial oxidation of oleic acid.

Resting cells of Saccharomyces cerevisiae (baker's yeast, type II; Sigma) were used to convert oleic acid into 10-hydroxyoctadecanoic acid with a 45% yield. Nocardia aurantia (ATCC 12674), Nocardia sp. (NRRL 5646), and Mycobacterium fortuitum (UI 53378) all converted oleic acid into 10-oxo-octadecanoic acid with 65, 55, and 80% yields, respectively. Structures of all metabolites were suggested by 1H and 13C nuclear magnetic resonance and by infrared and mass spectrometry. Structures of isomeric hydroxystearate and oxostearate derivatives and the stereochemical purity of hydroxystearates are difficult to prove unambiguously unless authentic standard compounds are available for spectral comparison. We describe the use of the chemical Baeyer-Villiger oxidation technique with 10-oxo-octadecanoic acid followed by mass spectral analysis of neutral extracts as a simple method to confirm the position of oxo-functional groups in the structures of fatty acid ketones. We further introduce a simple method based on 1H nuclear magnetic resonance analysis of diastereomeric S-(+)-O-acetylmandelate esters of hydroxystearates as a means of ascertaining stereochemical purities of hydroxy fatty acids.     

Microbial oxidation of oleic acid.

Resting cells of Saccharomyces cerevisiae (baker's yeast, type II; Sigma) were used to convert oleic acid into 10-hydroxyoctadecanoic acid with a 45% yield. Nocardia aurantia (ATCC 12674), Nocardia sp. (NRRL 5646), and Mycobacterium fortuitum (UI 53378) all converted oleic acid into 10-oxo-octadecanoic acid with 65, 55, and 80% yields, respectively. Structures of all metabolites were suggested by 1H and 13C nuclear magnetic resonance and by infrared and mass spectrometry. Structures of isomeric hydroxystearate and oxostearate derivatives and the stereochemical purity of hydroxystearates are difficult to prove unambiguously unless authentic standard compounds are available for spectral comparison. We describe the use of the chemical Baeyer-Villiger oxidation technique with 10-oxo-octadecanoic acid followed by mass spectral analysis of neutral extracts as a simple method to confirm the position of oxo-functional groups in the structures of fatty acid ketones. We further introduce a simple method based on 1H nuclear magnetic resonance analysis of diastereomeric S-(+)-O-acetylmandelate esters of hydroxystearates as a means of ascertaining stereochemical purities of hydroxy fatty acids.     

Fenton chemistry. Amino acid oxidation

The oxidation of amino acids by Fenton reagent (H2O2 + Fe(II] leads mainly to the formation of NH+4, alpha-ketoacids, CO2, oximes, and aldehydes or carboxylic acids containing one less carbon atom. Oxidation is almost completely dependent on the presence of bicarbonate ion and is stimulated by iron chelators at levels which are substoichiometric with respect to the iron concentration but is inhibited at higher concentrations. The stimulatory effect of chelators is not due merely to solubilization of catalytically inactive polymeric forms of Fe(OH)3 nor to the conversion of Fe(II) to complexes incapable of scavenging hydroxyl radicals. The results suggest that an iron chelate and another as yet unidentified form of iron are both required for maximal rates of amino acid oxidation. The metal ion-catalyzed oxidation of amino acids is likely a "caged" process, since the oxidation is not inhibited by hydroxyl radical scavengers, and the relative rates of oxidation of various amino acids by the Fenton system as well as the distribution of products formed (especially products of aromatic amino acids) are significantly different from those reported for amino acid oxidation by ionizing radiation. Several iron-binding proteins, peptides, and hemoglobin degradation products can replace Fe(II) or Fe(III) in the bicarbonate-dependent oxidation of amino acids. In view of their ability to sequester metal ions and their susceptibility to oxidation by H2O2 in the presence of physiological concentrations of bicarbonate, amino acids may serve an important role in antioxidant defense against tissue damage.     

Alterations in nicotinamide and adenine nucleotide systems during mixed-function oxidation of p-nitroanisole in perfused livers from normal and phenobarbital-treated rats

When rat liver nuclei were incubated with [adenine-3H]NAD, besides histone 1, histone 2A and especially histone 2B accepted 3H radioactivity. 3H radioactivity was also found on the non-histone proteins and on the small amounts of histones 1 and 3 released into the supernatant during incubation. [14C]Adenine uptake in vivo by liver and thymus nuclei showed radioactivity in histones 1 and 3. After digestion with Pronase and leucine aminopeptidase 14C- or 32P-labelled histone 3 released a serine phosphate-containing nucleotide, which on acid hydrolysis yielded ADP-ribose and serine phosphate. Serine phosphate was also found in the material from the nucleotide peaks from histones 2A and 2B. ADP-ribosylated histones 1 and 3 were more easily released from nuclei than their unmodified forms and showed higher [32P]Pi and [3H]lysine uptakes in vivo [Ord & Stocken (1975) FEBS Meet. Proc. 34, 113-125].     

Age-related changes in function of transfer ribonucleic acid of rat livers.

Changes in transfer ribonucleic acids during aging could be caused by alterations in regulation or mutation and give rise to slower and less accurate protein synthesis. Rodent liver parenchymal cells, purified from disaggregated livers, do decrease in ability to incorporate labeled amino acids during aging. Moreover, old rodents have a rapidly degraded fraction of liver soluble RNA which is absent from middle-aged animals. In addition, tRNAs purified from old unfractionated liver cannot be acylated as well as from young. High speed supernatant tRNAs from old and young liver are quite similar in acylation capacity. Analysis indicates that a defective subfraction of tRNA may be bound to the ribosomal fraction of the liver cell. Some evidence indicates that base modification levels differ in young and old rodent liver. Shifts in the proportions of lysine and serine isoacceptors during aging are consistent with this idea. One isoacceptor change is an increase in tRNAlys4, which is correlated with cell division capacity in other systems.     

Ascorbic acid and copper in linoleate oxidation. II. Ascorbic acid and copper as oxidation catalysts

Both ascorbic acid and copper were strong prooxidants in the oxidation of linoleate in a buffered (pH 7.0) aqueous dispersion at 37 degrees C. Minimum concentrations at which catalytic activity was detected were 1.3 x 10(-7) m for copper and 1.8 x 10(-6) m for ascorbic acid. For concentrations up to 10(-3) m, the increase in rate of oxidation with increase in concentration of catalyst was greater for ascorbic acid than for copper. Ascorbic acid had maximum catalytic activity at 2.0 x 10(-3) m, but was still prooxidant at the highest concentration tested (5.0 x 10(-2) m). Dehydroascorbic acid was a weaker prooxidant than ascorbic acid. Further degradation products of ascorbic acid were not prooxidant. In early stages of the oxidation autocatalytic behavior was observed with copper, but not with ascorbic acid. Ascorbic acid functioned as a true catalyst, i.e., it accelerated the reaction but it was not oxidized simultaneously with the linoleate. It is proposed that the dehydroascorbic acid radical initiates the linoleate oxidation reaction.