Multicomponent analysis of heme protein spectra in biological materials

Low grade intravascular hemolysis associates with peripheral nerve injury in type 2 diabetes

Type 2 diabetes (T2D) induces hyperglycemia, alters hemoglobin (Hb), red blood cell (RBC) deformability and impairs hemorheology. The question remains whether RBC breakdown and intravascular hemolysis (IVH) occur in T2D patients. We characterized RBC-degradation products and vesiculation in a case-control study of 109 T2D patients and 65 control subjects. We quantified heme-related absorbance by spectrophotometry and circulating extracellular vesicles (EV) by flow cytometry and electron microscopy. Heme-related absorbance was increased in T2D vs. control plasma (+57%) and further elevated in obese T2D plasma (+27%). However, large CD235a+ EV were not increased in T2D plasma. EV from T2D plasma, or shed by isolated T2D RBC, were notably smaller in diameter (-27%) and carried heme-related absorbance. In T2D plasma, higher heme-related absorbance (+30%) was associated to peripheral sensory neuropathy, and no other vascular complication. In vitro, T2D RBC-derived EV triggered endothelial stress and thrombin activation in a phosphatidylserine- and heme-dependent fashion. We concluded that T2D was associated with low-grade IVH. Plasma absorbance may constitute a novel biomarker of peripheral neuropathy in T2D, while flow cytometry focusing on large EV may be maladapted to characterize RBC EV in T2D. Moreover, therapeutics limiting IVH or neutralizing RBC breakdown products might bolster vasculoprotection in T2D.

Quinone and nitrofurantoin redox cycling by recombinant cytochrome b5 reductase

NADH cytochrome b₅ reductase mediates electron transfer from NADH to cytochrome b₅ utilizing flavin adenine dinucleotide as a redox cofactor. Reduced cytochrome b₅ is an important cofactor in many metabolic reactions including cytochrome P450-mediated xenobiotic metabolism, steroid biosynthesis and fatty acid metabolism, hemoglobin reduction, and methionine and plasmalogen synthesis. Using recombinant human enzyme, we discovered that cytochrome b5 reductase mediates redox cycling of a variety of quinones generating superoxide anion, hydrogen peroxide, and, in the presence of transition metals, hydroxyl radicals. Redox cycling activity was oxygen-dependent and preferentially utilized NADH as a co-substrate; NADH was 5-10 times more active than NADPH in supporting redox cycling. Redox cycling activity was greatest for 9,10-phenanthrenequinone and 1,2-naphthoquinone, followed by 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone (menadione), nitrofurantoin and 2-hydroxyestradiol. Using menadione as the substrate, quinone redox cycling was found to inhibit reduction of cytochrome b₅ by cytochrome b₅ reductase, as measured by heme spectral changes in cytochrome b₅. Under anaerobic conditions where redox cycling is inhibited, menadione had no effect on the reduction of cytochrome b₅. Chemical redox cycling by cytochrome b₅ reductase may be important in generating cytotoxic reactive oxygen species in target tissues. This activity, together with the inhibition of cytochrome b₅ reduction by redox-active chemicals and consequent deficiencies in available cellular cytochrome b₅, are likely to contribute to tissue injury following exposure to quinones and related redox active chemicals.

Photobiomodulation devices for hair regrowth and wound healing: a therapy full of promise but a literature full of confusion

Photobiomodulation is reported to positively influence hair regrowth, wound healing, skin rejuvenation and psoriasis. Despite rapid translation of this science to commercial therapeutic solutions, significant gaps in our understanding of the underlying processes remain. The aim of this review was to seek greater clarity and rationality specifically for the selection of optical parameters for studies on hair regrowth and wound healing. Our investigation of 90 reports published between 1985 and 2015 revealed major inconsistencies in optical parameters selected for clinical applications. Moreover, poorly understood photoreceptors expressed in skin such as cytochrome c oxidase, cryptochromes, opsins etc. may trigger different molecular mechanisms. All this could explain the plethora of reported physiological effects of light. To derive parameters for optimal clinical efficacy of photobiomodulation, we recommend a more rational approach to underpin clinical studies, with research on molecular targets and pathways using well-defined biological model systems to enable translation of optical parameters from in vitro to in vivo. Furthermore, special attention needs to be paid when conducting studies for hair regrowth, aiming for double-blind, placebo-controlled randomized clinical trials as the gold standard for quantifying hair growth.

Heme of consumed red meat can act as a catalyst of oxidative damage and could initiate colon, breast and prostate cancers, heart disease and other diseases

Dietary epidemiological studies indicate correlations between the consumption of red meat and/or processed meat and cancer of the colon, rectum, stomach, pancreas, bladder, endometrium and ovaries, prostate, breast and lung, heart disease, rheumatoid arthritis, type 2 diabetes and Alzheimer's disease. The correlation of all these major diseases with dietary red meat indicates the presence of factors in red meat that damage biological components. This hypothesis will focus on the biochemistry of heme compounds and their oxidative processes. Raw red meat contains high levels of oxymyoglobin and deoxymyoglobin and oxyhemoglobin and deoxyhemoglobin and cytochromes in muscle and other tissues. Cooked and processed meat contain hemichromes and hemochromes. After being eaten heme proteins are hydrolyzed to amino acids and peptides and the heme group which is coordinated with strong ligands. The iron of heme coordinates to the sulfur, nitrogen or oxygen of amino acids and peptides and other biological components. The coordinated heme groups are absorbed and transported by the blood to every organ and tissue. Free and coordinated heme preferentially catalyze oxidative reactions. Heme catalyzed oxidations can damage lipids, proteins, DNA and other nucleic acids and various components of biological systems. Heme catalysis with hydroperoxide intermediates can initiate further oxidations some of which would result in oxidative chain reactions. Biochemical and tissue free radical damage caused by heme catalyzed oxidations is similar to that resulting from ionizing radiation. Oxidative biochemical damage is widespread in diseases. It is apparent that decreasing the amount of dietary red meat will limit the level of oxidative catalysts in the tissues of the body. Increasing consumption of vegetables and fruits elevates the levels of antioxidative components, for example, selenium, vitamin E, vitamin C, lycopene, cysteine-glutathione and various phytochemicals. These detrimental processes of heme catalysis of oxidative damage hypothesized here are not well recognized. More investigative studies in this field need to be done.

Characterization of mitochondrial and extra-mitochondrial oxygen consuming reactions in human hematopoietic stem cells. Novel evidence of the occurrence of NAD(P)H oxidase activity

This study was aimed to characterize the mitochondrial and extra-mitochondrial oxygen consuming reactions in human CD34+ hematopoietic stem cells. Cell samples were collected by apheresis following pre-conditioning by granulocyte colony-stimulating factor and isolated by anti-CD34 positive immunoselection. Polarographic analysis of the CN-sensitive endogenous cell respiration revealed a low mitochondrial oxygen consumption rate. Differential absorbance spectrometry on whole cell lysate and two-dimensional blue native-PAGE analysis of mitoplast proteins confirmed a low amount of mitochondrial respiratory chain complexes thus qualifying the hematopoietic stem cell as a poor oxidative phosphorylating cell type. Confocal microscopy imaging showed, however, that the intracellular content of mitochondria was not homogeneously distributed in the CD34+ hematopoietic stem cell sample displaying a clear inverse correlation of their density with the expression of the CD34 commitment marker. About half of the endogenous oxygen consumption was extra-mitochondrial and completely inhibitable by enzymatic scavengers of reactive oxygen species and by diphenylene iodinium. By spectral analysis, flow cytometry, reverse transcriptase-PCR, immunocytochemistry, and immunoprecipitation it was shown that the extra-mitochondrial oxygen consumption was contributed by the NOX2 and NOX4 isoforms of the O2-*. producer plasma membrane NAD(P)H oxidase with low constitutive activity. A model is proposed suggesting for the NAD(P)H oxidase a role of O2 sensor and/or ROS source serving as redox messengers in the activation of intracellular signaling pathways leading (or contributing) to mitochondriogenesis, cell survival, and differentiation in hematopoietic stem cells.

Analysis of oxidized heme proteins and its application to multiple antioxidant protection

Oxidation in tissues and homogenates can be determined by the analysis of oxidized heme proteins. Oxidation of heme proteins can be measured by spectral changes and the deconvolution of the spectra of mixtures of heme proteins by a spreadsheet heme spectra analysis program (HSAP), incorporating the spectra of the individual pure heme proteins. HSAP also is used to analyze the spectra of mixtures of heme proteins found in the literature. HSAP is applied in measuring the protective effects in rats of multiple antioxidants suitable for use in humans for protection against diseases.

Fluorescent lipid oxidation products and heme spectra index antioxidant efficacy in kidney tissue of hamsters

Studies ranging from epidemiological to molecular suggest that dietary antioxidants protect against chronic diseases. The hypothesis was investigated that hamster kidney homogenate are better protected against induced oxidative damage after animals were fed a purified vitamin E deficient diet supplemented with 30 international units (IU) vitamin E/kg (30 IU diet) than fed the minimum required 3 IU vitamin E/kg (3 IU diet). The addition of 200 mg (+)-catechin to the 3 IU diet may offer protection. The effects of dietary (+)-catechin and alpha-tocopherol on tissue oxidizability were investigated by measuring (i) fluorescent products in lipid extracts, (ii) heme protein oxidation and (iii) heme destruction. A rapid initial increase of oxidation markers was measured over the 4 h incubation period for iron + ascorbate induced oxidation and a constant increase for lipoxygenase catalyzed products. Analysis of covariance over time and comparison at specific incubation times showed that iron + ascorbate induced homogenates from hamsters fed the 30 IU diet generated less fluorescent products and oxidized heme proteins than homogenates from the 3 IU or the 3 IU plus (+)-catechin fed animals. Incubation with lipoxygenase produced more lipid fluorescent products and heme protein oxidation in the 3 IU than in the 30 IU vitamin E group. In conclusion, supplementary dietary vitamin E but not supplementary (+)-catechin in a diet containing the minimum requirement of vitamin E for the species enhances oxidative resistance of kidney tissue.

Measuring the oxidation of heme compounds in heart homogenates from rats supplemented with dietary antioxidants

Protection by antioxidant nutrients against oxidative damage in rat heart homogenates was studied. Following spontaneous oxidation of heart homogenates from rats fed vitamin E, selenium, or beta-carotene, oxidized heme proteins (OHP) and thiobarbituric acid reactive substances (TBARS) were measured. The absorbance spectra of oxidized and reduced heme proteins were analyzed with a heme spectral analysis program (HSAP) developed in this laboratory. HSAP is a multicomponent analysis program that uses successive approximations and computer spread-sheet solver functions to deconvolute a complex absorbance spectrum into individual heme protein spectra. Vitamin E markedly decreased formation of OHP, and vitamin E, selenium, or beta-carotene significantly lowered the production of TBARS during spontaneous oxidation of heart homogenates compared with homogenates from rats fed antioxidant-deficient diets. Pyridine hemochrome analysis showed that the total amounts of heme proteins present in the homogenates decreased during the oxidative incubation period. The formation of OHP correlated significantly with the amount of TBARS produced and could be simulated as a function of the oxidative and protective reactions involved in the oxidation of rat heart homogenates.