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At least 1,405 records · Page 78Linked to original sources
PubMed1998

Changes in cytochrome oxidase activity in brown adipose tissue during oestrous cycle in the rat.

Cold-acclimated female Wistar rats were killed at a known phase of the oestrous cycle to investigate whether natural fluctuations of female sex steroids during the cycle are mirrored by changes in brown adipose tissue (BAT) activity. Four phases: proestrus, oestrus, dioestrus I and dioestrus II, were identified by the cells types appearing in vaginal smears. BAT was removed and analysed for composition and specific indicators of BAT activity. No changes in BAT mass, protein or mitochondrial content were detected during the cycle. Thermogenesis was also unchanged as judged by both lipid multilocularity and mitochondrial GDP-binding. However, cytochrome c oxidase (COX) activity did cycle with a minimum at proestrus and a maximum at dioestrus I. The involvement of oestradiol in such a cycle is suggested by the fact that oestradiol treatment decreased COX activity to values similar to those found in proestrus. The physiological function of a cyclic oxidative capacity remains to be elucidated.

Adipose Tissue, Brown↗
PubMed1983

Changes in tissue growth, concentrations of copper, iron, cytochrome oxidase and superoxide dismutase subsequent to dietary or genetic copper deficiency in mice.

Experiments were conducted in suckling mice to investigate copper-dependent anemia. Brindled (Mobr/y) mice, which are not anemic, were compared to their normal brothers (Mo+/y) as well as to anemic suckling mice that were copper-deficient (-Cu) because their dams were consuming a diet low in copper and a fourth group of suckling mice that served as dietary controls (+Cu). Compared to +Cu and Mo+/y mice, -Cu mice were smaller and exhibited cardiac hypertrophy and significant atrophy of lymphoid tissues (spleen and thymus), Mobr/y mice were also small and demonstrated modest atrophy of both liver and spleen. Cu levels were decreased in all -Cu mouse tissues studied, whereas Fe levels tended to be unaltered. Mobr/y mice also exhibited lower tissue Cu levels in soft tissues, except for kidney and small intestine; however, Cu levels in Mobr/y mice were greater than in -Cu mice. Functional copper deficiency was demonstrated in -Cu tissues by decreases in cytochrome c oxidase (CO) and cuprozinc-superoxide dismutase (SOD). The magnitude of the change was tissue specific. Mobr/y tissues, which were low in Cu, also exhibited decreased SOD and CO activity. However, the drop in Mobr/y tissue was less than in -Cu tissue. This was most pronounced in bone marrow, where both CO and SOD were four times higher in Mobr/y than in -Cu mice. Both Mobr/y and -Cu mice had low serum ceruloplasmin activities. The presence of anemia in -Cu mice and the absence of anemia in Mobr/y mice may result from a more severe copper-deficient state in erythropoietic tissues in -Cu mice rather than from differences in ceruloplasmin activity.

Animals↗
PubMed1999

Maturation of NADPH-d activity in the rat's barrel-field cortex and its relationship to cytochrome oxidase activity.

Histochemical detection of NADPH-d activity in rat barrel-field cortex reveals four types of distributions. (i) A transient, diffuse neuropil staining is visible in the cortical plate and in deeper layers until postnatal day (P) 4. Thereafter, until P15, it is segregated in whisker-specific patches in layer IV, then the pattern gradually disappears, becoming virtually indistinct by P21. This transient patterning of diffuse NADPH-d activity in layer IV disappears after cortical injections of kainic acid and is affected by neonatal damage to the contralateral snout. An intense labeling (ii) of scattered cells and (iii) of a plexus of fibers is present. With maturation, the cells become localized mostly in layers II/III, in the lower part of layer V, and in layer VI. They are sparse in layer I, in upper layer V, and in layer IV where their somata are located primarily in the interbarrel septa. (iv) Light staining of cortical neurons is detected mostly in layers II-IV but occasionally also in layers V-VI. Cytochrome c oxidase (CO)-positive patches associated with barrels are first detected in layer IV around P4-P5; their staining density increases with development, then stays high. In the adult, CO activity is moderate in supragranular layers, highest in the barrels in layer IV, low in upper layer V, medium dense in the deeper half of layer V, and low in lamina VI. Thus, NADPH-d and CO activities are not necessarily colocalized in the rodent barrel-field cortex. The varied (transient and long-lasting) distributions of NADPH-d activity indicate that the enzyme and its associated production of NO serve multiple roles in developing and adult barrel-field cortex.

Animals↗
PubMed1995

Regional distributions of hippocampal Na+,K(+)-ATPase, cytochrome oxidase, and total protein in temporal lobe epilepsy.

Na+,K(+)-ATPase (the sodium pump) is a ubiquitous enzyme that consumes ATP to maintain an adequate neuronal transmembrane electrical potential necessary for brain function and to dissipate ionic transients. Reductions in sodium pump function augment the sensitivity of neurons to glutamate, increasing excitability and neuronal damage in vitro. Temporal lobe epilepsy (TLE) is one disease characterized by hyperexcitability and marked hippocampal neuronal losses that could depend in part, on impaired sodium pump capacity secondary to changes in sodium pump levels and/or insufficient ATP supply. To assess whether abnormalities in the sodium pump occur in this disease, we used [3H]ouabain to determine the density of Na+,K(+)-ATPase for each anatomic region of hippocampus by in vitro autoradiography. Tissues were surgically obtained from epileptic patients with hippocampal sclerosis and compared with specimens from patients with seizures originating from temporal lobe tumors and autopsy controls. Changes in cellular population arising from neuronal losses or gliosis were assessed by protein densities derived from quantitative computerized densitometry of Coomassie-stained tissue sections. We estimated regional differences in capacity for ATP generation by determining cytochrome c oxidase (CO) activity. Principal neurons of hippocampus exhibit high levels of sodium pump enzyme. Both epilepsy groups exhibited slight but significant increases in sodium pump density/unit mass of protein in the dentate molecular layer, CA2, and subiculum as compared with autopsy controls. Greater hilar sodium pump density was also observed in sclerotic hippocampi. In contrast, CO activity was reduced in both epilepsy types throughout hippocampus. Results suggest that although sodium pump protein in surviving neurons appears to be upregulated in epilepsy, sodium pump capacity may be limited by the reduced levels of CO activity. Functional reduction in sodium pump capacity may be an important factor in hyperexcitability and neuronal death.

Autoradiography↗
PubMed1983

Interaction in cytochrome c oxidase between cytochrome a3 ligated with nitric oxide and cytochrome a.

EPR spectra of nitric oxide complexes of cytochrome c oxidase were studied as a function of temperature in the fully reduced form and in a mixed valence form. In the 12-77 K range, temperature-dependent motion changed the EPR spectral line shape of the mixed valence form but not the fully reduced form. Two separate hypotheses which both indicate cytochrome a-cytochrome a3 interaction could account for this phenomenon: i.e. either, in response to redox changes at cytochrome a, a changed ligand binding environment occurs at cytochrome a3 which has conformations that down to 40 K can interconvert on a 10(8) s-1 time scale, or dipolar spin-spin interaction occurs between the NO-liganded a3 center and a paramagnetic metal center in cytochrome a. This interaction is then modulated by the temperature-dependent spin-lattice relaxation behavior of the center in cytochrome a. If this latter hypothesis is correct, the intercenter distance can be estimated at 15 A, and the more likely interacting center can be predicted to be the heme moiety of cytochrome a.

Animals↗
PubMed1992

Baculovirus mediated expression of human phagocytic cell oxidase cytochrome b558 in sf9 insect cells.

Chronic granulomatous disease (CGD) results from deficient production of components of the phagocyte NADPH oxidase. Most commonly affected is cytochrome b558, a heterodimer composed of a 22-kDa protein (p22phox) noncovalently bound to a 91-kDa transmembrane glycoprotein (gp91phox). CGD phagocytes lack both p22phox and gp91phox peptides when either gene is affected, suggesting that both peptides must be produced for individual subunit stability. Both genes have been cloned, but eukaryotic expression of recombinant gp91phox has not been reported. To investigate the stability and interaction of cytochrome b558 subunits, we introduced p22phox and gp91phox cDNA into recombinant baculoviruses. Recombinant gp91phox (rgp91phox) and p22phox (rp22phox) were detected individually and together in the same cells by in situ immunofluorescence and by SDS-PAGE immunoblotting of membranes from sf9 cells infected with baculovirus constructs. Formation of rp22phox/rgp91phox complexes was demonstrated by coprecipitation using subunit-specific antibodies. This study demonstrates for the first time that cDNA encoding either subunit is capable of initiating production of stable recombinant cytochrome b558 subunits in eukaryotic cells.

Animals↗
PubMed1994

Mitochondrial enzyme deficiencies in Down's syndrome.

Defects in cytochrome oxidase (CO; complex 4) have recently been demonstrated in blood platelets and in brain tissue from patients with Alzheimer's disease (AD) with possible etiological implications. Because of pathogenetic similarities with AD, we have measured the activities of several mitochondrially localised enzymes in the blood platelets of individuals afflicted with trisomy-21 (Down's syndrome). The activities of monoamine oxidase, cytochrome oxidase, isocitrate dehydrogenase, and glutamate dehydrogenase were assayed in washed platelets from sixty caucasian, male and female control individuals (ages 18-60) and ten, young Down's Syndrome patients (ages 9-21). Significant reductions in the activities of monoamine oxidase, cytochrome oxidase, and isocitrate dehydrogenase were found. In all cases the average activities in Down's syndrome individuals were approximately two-thirds those of controls (DS/Controls = 0.68, 0.67, 0.64 respectively). The activity of the fourth enzyme studied, glutamate dehydrogenase, was found to be similar to controls. Results suggest that these reductions are a consequence of a generalised mitochondrial disturbance which may lie behind some pathogenetic aspect(s) of the disease.

Adolescent↗