Immunological identification and determination of xanthine oxidase in cells and tissues.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
G Bruder
Publications and source records attributed to G Bruder.
Characteristics of membrane-bound and soluble forms of xanthine oxidase from milk and endothelial cells of capillaries.
Xanthine oxidase (xanthine:O2 oxidoreductase, EC 1.2.3.2) was purified from bovine milk lipid globules to electrophoretic homogeneity (Mr 155,000) and antibodies were raised against it in rabbits. By immunolocalization techniques, the xanthine oxidase antigen was detected in milk lipid globules and mammary gland epithelium, but also in capillary endothelium from various tissues, including liver, lung and intestine. These findings were paralleled by measurements of xanthine oxidase activities in the tissues, both in a membrane-associated and a soluble form. Addition of hypoxanthine to fractions containing native xanthine oxidase did not promote lipid peroxidation, in contrast to the widely used in vitro system for lipid peroxidation which involves addition of xanthine oxidase preparations. Extraction with buffers of high ionic strength and with nonionic detergents removed only part of the enzyme from the membranes. Immunoprecipitates from the soluble supernatant fractions, using anti-xanthine oxidase IgG, were enriched in the Mr 155,000 polypeptide. Patterns of proteolytic cleavage products of the xanthine oxidase monomer from capillaries and milk lipid globules were similar but not identical. Immunoprecipitates from soluble fractions of milk lipid globules and tissues were enriched in both xanthine oxidase and NADH-cytochrome c reductase activities. Electrophoretic separation of proteins from milk lipid globule membranes under non-denaturing conditions revealed a close correlation of xanthine oxidase and part of the NADH-cytochrome c reductase activity, but showed different activity profiles of NADH-ferricyanide reductase and xanthine oxidase.
Adipose Tissue↗
Localization of xanthine oxidase in mammary-gland epithelium and capillary endothelium.
Xanthine oxidase, an iron-sulfur molybdenum flavoprotein known to generate superoxide radical, was demonstrated in several bovine tissues. The enzyme (155 kd polypeptide) was purified from bovine milk lipid globules and antibodies were raised that allowed precipitation of the enzyme without inactivation of enzymatic activity. By immunolocalization techniques at light and electron microscope levels, the antigen was found in milk-secreting epithelial cells but not in epithelial cells of several other tissues. In a number of tissues, including mammary gland, liver, heart, lung and intestine, antibodies to xanthine oxidase stained only endothelial cells of capillaries, including sinusoids, but not endothelia of larger blood vessels and endocard. In both milk-secreting epithelial and capillary endothelial cells, xanthine oxidase was distributed throughout the cytoplasm. Results from biochemical and immunological studies suggest that xanthine oxidase is similar in the various tissues examined and may serve similar redox functions.
Animals↗
Lateralized auditory processing in depression: dichotic click detection.
The intensity needed to detect dichotic click stimuli was measured in 14 bipolar depressed patients, 19 unipolar depressed patients, and 15 normal controls. The results replicated, in unmedicated bipolar depressed patients, an earlier finding of reversed lateral asymmetry in medicated affective psychotic patients. Two new findings concern the relation of lateral asymmetry patterns to diagnostic subtypes of the Research Diagnostic Criteria and symptom ratings on the Schedule for Affective Disorders and Schizophrenia. First, patients with bipolar disorders (history of mania or hypomania) were more likely than patients with unipolar disorders to display reversed lateral asymmetry. Second, greater severity of depressive or endogenous symptoms was associated with less lateral asymmetry.
Adult↗
Plasma membranes from intestinal microvilli and erythrocytes contain cytochromes b5 and P-420.
The presence of cytochromes b5, P-450 and P-420 and activities of NADH- and NADPH-cytochrome c redutases were determined in plasma membranes isolated from microvilli of the chick and rat intestinal epithelium and erythrocyte membranes from chick, rat and man. The results are compared with the amounts of these components found in microsomal fractions from intestinal epithelium and in nuclear membranes from chick erythrocytes. Plasma membranes from intestinal microvilli and from erythrocytes contained significant amounts of NADH-cytochrome c reductase activity and of a pigment spectrophotometrically indistinguishable from rat liver microsomal cytochrome b5. In addition, cytochrome b5 fragments were prepared from the membranes by limited trypsin digestion and consisted of two to four components with Mr values in the range 10 000-13 500. In low-temperature difference spectra, the presence of a second cytochrome was noted which was similar to cytochrome P-420. Cytochrome P-450 and NADPH-cytochrome c reductase activities were not detected in plasma membrane fractions in significant concentrations but were present in the corresponding endomembrane fractions. These findings in highly purified, well defined plasma membrane fractions, in which contamination by endomembranes is minimal, strengthen the evidence for the existence of cytochrome-containing redox systems in plasma membranes of various cells and suggest that such redox components are general components of the cell surface. Possible functions and origins of these redox components in plasma membranes are discussed.
Animals↗
Auditory sensitivity in psychiatric patients and non-patients: monotic click detection.
The sensitivity in detecting a click was measured separately for the right and left ear of psychiatric patients and non-patient controls using a three-interval forced-choice staircase procedure. Patients with affective disorders showed reduced right ear sensitivity, while schizophrenic patients did not show reduced sensitivity. Lower sensitivity correlated with higher structured-interview ratings of speech retardation.
Adolescent↗
Reaction time facilitation in affective psychotic patients.
The extent to which the second member of a pair of monotic clicks facilitates simple reaction time was examined for 35 psychiatric patients and 43 non-patient controls across 2 studies. Affective psychotic patients showed greater reaction time facilitation than did either schizophrenic patients or non-patient controls. Computer simulations of a 'statistical facilitation' model for these data are also presented.
Adolescent↗
Distribution of enzymes involved in metabolism of polycyclic aromatic hydrocarbons among rat liver endomembranes and plasma membranes.
The distribution of membrane-bound enzymes involved in the metabolism of polycyclic aromatic hydrocarbons was investigated in the same animals, in membrane fractions from rat liver: monooxygenase, cytochromes P-450 and P-420, NADPH-cytochrome P-450 reductase, cytochrome b5, NADH-cytochrome b5 reductase, epoxide hydrolase, glutathione-S-transferase, and UDP-glucuronyltransferase. The purity of the fractions (rough and smooth endoplasmic reticulum (ER), nuclei, nuclear membranes, Golgi apparatus, plasma membranes, and mitochondria) was controlled by electron microscopic morphometry, chemical analysis, and determination of marker enzyme activities. Specific activities invariably were highest in ER. With respect to the distribution between smooth and rough ER, the enzymes fell into two groups: Epoxide hydrolase, monooxygenase, NADPH-cytochrome P-450 reductase, NADH-cytochrome b5 reductase, and the concentrations of cytochromes P-450 and b5 were higher in smooth ER; by contrast, UDP-glucuronyltransferase (maximally activated) and membrane-associated glutathione-S-transferase activities were lower in smooth ER. The non-ER fractions also had significant activities of the enzymes, but to different extents: (1) Nuclei and nuclear membranes showed high UDP-glucuronyltransferase activities (on a phospholipid basis 55-65% of that of rough ER) which did not exhibit latency. (2) Plasma membrane, Golgi apparatus, and nuclear membrane fractions had relatively high epoxide hydrolase and NADH-cytochrome b5 reductase activities as well as high concentrations of cytochromes b5 and P-450 (20-30% of levels present in smooth ER on a phospholipid basis). (3) In mitochondria (whole organelles), glutathione-S-transferase. UDP-glucuronyltransferase, and NADH-cytochrome b5 reductase activities were high, in contrast to exceedingly low (or absent) amounts of cytochrome P-450 and activities of cytochrome P-450 reductase, monooxygenase, and epoxide hydrolase. The data show that (i) aromatic hydrocarbons are metabolized not only in ER membranes but also in other kinds of membranes, including Golgi apparatus and plasma membrane, and (ii) the mode and extent of this metabolism can differ in different membranes. Such differences of activities of enzymes present in the specific membranes might lead to differences of the intracellular distribution of reactive and inactive metabolites of aromatic hydrocarbons and thus may be important in diversification and regulation of metabolic pathways of carcinogenic compounds.
7-Alkoxycoumarin O-Dealkylase↗
B-type cytochromes in plasma membranes isolated from rat liver, in comparison with those of endomembranes.
Fractions of plasma membranes, Golgi apparatus, endoplasmic reticulum (ER), and nuclear envelope were isolated from rat liver and were characterized by electron microsocpe and biochemical methods. The purity of the fractions was controlled by morphometry and by marker enzyme activities. Amounts of cytochromes b5, P-450, and P-420 were measured, as well as the NADPH- and NADPH-cytochrome c reductase activities. The pigments of the microsomal electron transport system were found in all membrane fractions in relatively high amounts, thus excluding an origin by microsomal contamination. Purified preparations of plasma membrane and Golgi apparatus contained approximately 30% of the cytochrome b5 and cytochrome P-450 + P-420 found in ER membranes. Plasma membranes were also characterized by a high ratio of P-420/450. Degradation of cytochromes P-450 and P-420 was relatively rapid in all fractions, except in the ER. Cytochrome b5 extracted from plasma membranes was spectrophotometrically and enzymatically indistinguishable from ER cytochrome b5. However, immunnlogical characterization with rabbit antibodies against the trypsin-resistant core of microsomal cytochrome b5 showed the presence of at least two types of cytochrome b5 in ER membranes, in contrast to the plasma membranes in which only one of these components was detected. This immunological differentiation also demonstrates that the plasma membrane-bound cytochrome b5 is endogenous to this membrane and does not reflect contamination by ER elements. We conclude that cytochromes b5, P-450, and P-420 are not confined only to ER and nuclear membranes but also occur in signficant amounts in Golgi apparatus and plasma membranes. The findings are discussed in relation to observations of similar redox components in Golgi apparatus, secretory vesicles, and plasma membranes of other cells.
Animals↗
Dichotic perception: evidence for right hemisphere dysfunction in affective psychosis.
The association between lateralized hemispheric dysfunction and psychiatric diagnosis was investigated with a measure of summation of dichotic clicks and with a dichotic competing message task. Ear asymmetries of affective psychotic patients were similar to those of right temporal lesioned controls and differed from those of schizophrenic patients and normal controls. In contrast, schizophrenic patients did not display abnormal auditory perceptual asymmetries.
Adult↗
The B-type cytochrome in endoplasmic reticulum of mammary gland epithelium and milk fat globule membranes consists of two components cytochrome b5 and cytochrome P-420.
Explore the source record for details and available documents.
Animals↗
Redox constituents in milk fat globule membranes and rough endoplasmic reticulum from lactating mammary gland.
Milk fat globule membranes (MFGM) and rough endoplasmic reticulum (RER) membranes were isolated from milk and lactating mammary gland from the cow and were characterized by biochemical and electron microscope methods in terms of gross composition (proteins, phospholipids, neutral lipids, cholesterol, RNA, and DNA) and purity. Both fractions contained significant amounts of a b-type cytochrome with several properties similar to those of cytochrome b5 from liver, as well as a rotenone-insensitive NADH- and NADPH-cytochrome c reductase. The b-type cytochrome content in the apical plasma membrane-derived MFGM was of the same order of magnitude as it was in RER membranes. It was characterized by a high resistance to extraction by low- and high-salt concentrations and nonionic detergents. MFGM contained much more flavin and much higher activities of xanthine oxidase than the RER membranes. The same redox components were found in MFGM and mammary RER from women, rats, mice, and goats, but in absolute contents great differences between the species were noted. The cytochromes described here differed from liver cytochrome b5 in some spectral properties. The alpha-band of the reduced hepatic cytochrome b5 is asymmetric with a maximum at 555 nm that is split into two distinct peaks at low temperatures. The alpha-band of the b-type cytochromes from MFGM and mammary RER appears as one symmetrical peak at about 560 nm that is not split at low temperatures. When treated with cyanide, MFGM and mammary microsomes showed difference spectra of a reduced b-type cytochrome. Under the same conditions, liver microsomes gave a completely different spectrum. These findings demonstrate the presence of a b-type cytochrome and associated redox enzymes in MFGM, i.e., a derivative of the apical cell surface membrane that is regularly used for envelopment of the milk fat globule during secretion.
Animals↗