A new type of inherited catalase deficiencies: its characterization and comparison to the Japanese and Swiss type of acatalasemia

Role of Oxidative Stress in the Pathogenesis of Atherothrombotic Diseases

Oxidative stress is generated by the imbalance between reactive oxygen species (ROS) formation and antioxidant scavenger system’s activity. Increased ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical and peroxynitrite, likely contribute to the development and complications of atherosclerotic cardiovascular diseases (ASCVD). In genetically modified mouse models of atherosclerosis, the overexpression of ROS-generating enzymes and uncontrolled ROS formation appear to be associated with accelerated atherosclerosis. Conversely, the overexpression of ROS scavenger systems reduces or stabilizes atherosclerotic lesions, depending on the genetic background of the mouse model. In humans, higher levels of circulating biomarkers derived from the oxidation of lipids (8-epi-prostaglandin F_2α, and malondialdehyde), as well as proteins (oxidized low-density lipoprotein, nitrotyrosine, protein carbonyls, advanced glycation end-products), are increased in conditions of high cardiovascular risk or overt ASCVD, and some oxidation biomarkers have been reported as independent predictors of ASCVD in large observational cohorts. In animal models, antioxidant supplementation with melatonin, resveratrol, Vitamin E, stevioside, acacetin and n-polyunsaturated fatty acids reduced ROS and attenuated atherosclerotic lesions. However, in humans, evidence from large, placebo-controlled, randomized trials or prospective studies failed to show any athero-protective effect of antioxidant supplementation with different compounds in different CV settings. However, the chronic consumption of diets known to be rich in antioxidant compounds (e.g., Mediterranean and high-fish diet), has shown to reduce ASCVD over decades. Future studies are needed to fill the gap between the data and targets derived from studies in animals and their pathogenetic and therapeutic significance in human ASCVD.

Mechanism-Based Biomarker Prediction for Low-Grade Inflammation in Liver and Adipose Tissue

Metabolic disorders, such as obesity and type 2 diabetes have a large impact on global health, especially in industrialized countries. Tissue-specific chronic low-grade inflammation is a key contributor to complications in metabolic disorders. To support therapeutic approaches to these complications, it is crucial to gain a deeper understanding of the inflammatory dynamics and to monitor them on the individual level. To this end, blood-based biomarkers reflecting the tissue-specific inflammatory dynamics would be of great value. Here, we describe an in silico approach to select candidate biomarkers for tissue-specific inflammation by using a priori mechanistic knowledge from pathways and tissue-derived molecules. The workflow resulted in a list of candidate markers, in part consisting of literature confirmed biomarkers as well as a set of novel, more innovative biomarkers that reflect inflammation in the liver and adipose tissue. The first step of biomarker verification was on murine tissue gene-level by inducing hepatic inflammation and adipose tissue inflammation through a high-fat diet. Our data showed that in silico predicted hepatic markers had a strong correlation to hepatic inflammation in the absence of a relation to adipose tissue inflammation, while others had a strong correlation to adipose tissue inflammation in the absence of a relation to liver inflammation. Secondly, we evaluated the human translational value by performing a curation step in the literature using studies that describe the regulation of the markers in human, which identified 9 hepatic (such as Serum Amyloid A, Haptoglobin, and Interleukin 18 Binding Protein) and 2 adipose (Resistin and MMP-9) inflammatory biomarkers at the highest level of confirmation. Here, we identified and pre-clinically verified a set of in silico predicted biomarkers for liver and adipose tissue inflammation which can be of great value to study future development of therapeutic/lifestyle interventions to combat metabolic inflammatory complications.

Oxidative stress pathways in pancreatic β-cells and insulin-sensitive cells and tissues: importance to cell metabolism, function, and dysfunction

It is now accepted that nutrient abundance in the blood, especially glucose, leads to the generation of reactive oxygen species (ROS), ultimately leading to increased oxidative stress in a variety of tissues. In the absence of an appropriate compensatory response from antioxidant mechanisms, the cell, or indeed the tissue, becomes overwhelmed by oxidative stress, leading to the activation of intracellular stress-associated pathways. Activation of the same or similar pathways also appears to play a role in mediating insulin resistance, impaired insulin secretion, and late diabetic complications. The ability of antioxidants to protect against the oxidative stress induced by hyperglycemia and elevated free fatty acid (FFA) levels in vitro suggests a causative role of oxidative stress in mediating the latter clinical conditions. In this review, we describe common biochemical processes associated with oxidative stress driven by hyperglycemia and/or elevated FFA and the resulting clinical outcomes: β-cell dysfunction and peripheral tissue insulin resistance.

Pharmacogenetic considerations in the treatment of gout

Gout is one of the most common forms of arthritis and the prevalence is increasing. Management comprises rapid and effective control of the inflammation in acute gout and sustained urate lowering in the long term. Improving the outcomes for cheaper old drugs and for the increasing number of new, more expensive agents is an important clinical goal. The role of pharmacogenetics in predicting response and adverse events to gout therapies is of considerable interest. Currently, prospective screening is employed to detect HLA-B*5801 carriage and glucose-6-phosphate dehydrogenase deficiency, to minimize occurrence of allopurinol hypersensitivity and pegloticase-related hemolytic anemia. In the future it is likely that other genetic markers of drug response will make the transition to clinical practice to further improve the efficacy and safety of gout therapies. In this review, we will examine the potential clinical relevance of specific genetic variants in the management of gout.

Manganese superoxide dismutase and oxidative stress modulation

Oxidative stress is characterized by imbalanced reactive oxygen species (ROS) production and antioxidant defenses. Two main antioxidant systems exist. The nonenzymatic system relies on molecules to directly quench ROS and the enzymatic system is composed of specific enzymes that detoxify ROS. Among the latter, the superoxide dismutase (SOD) family is important in oxidative stress modulation. Of these, manganese-dependent SOD (MnSOD) plays a major role due to its mitochondrial location, i.e., the main site of superoxide (O(2)(·-)) production. As such, extensive research has focused on its capacity to modulate oxidative stress. Early data demonstrated the relevance of MnSOD as an O(2)(·-) scavenger. More recent research has, however, identified a prominent role for MnSOD in carcinogenesis. In addition, SOD downregulation appears associated with health risk in heart and brain. A single nucleotide polymorphism which alters the mitochondria signaling sequence for the cytosolic MnSOD form has been identified. Transport into the mitochondria was differentially affected by allelic presence and a new chapter in MnSOD research thus begun. As a result, an ever-increasing number of diseases appear associated with this allelic variation including metabolic and cardiovascular disease. Although diet and exercise upregulate MnSOD, the relationship between environmental and genetic factors remains unclear.

Development of a new biosensor for determination of catalase activity

Catalase is one of the major antioxidant enzymes that catalyzes the hydrolysis of H2O2. The aim of this study was to suggest a new method for the assay of catalase activity. For this purpose, an amperometric biosensor based on glucose oxidase for determination of catalase activity was developed. Immobilization of glucose oxidase was made by a cross-linking method with glutaraldehyde on a Clark-type electrode (dissolved oxygen probe). Optimization and characterization properties of the biosensor were studied and determination of catalase activity in defined conditions was investigated in artificial serum solution. The results were compared with a reference method.

The MnSOD Ala16Val SNP: relevance to human diseases and interaction with environmental factors

The relevance of reactive oxygen species (ROS) production relies on the dual role shown by these molecules in aerobes. ROS are known to modulate several physiological phenomena, such as immune response and cell growth and differentiation; on the other hand, uncontrolled ROS production may cause important tissue and cell damage, such as deoxyribonucleic acid oxidation, lipid peroxidation, and protein carbonylation. The manganese superoxide dismutase (MnSOD) antioxidant enzyme affords the major defense against ROS within the mitochondria, which is considered the main ROS production locus in aerobes. Structural and/or functional single nucleotide polymorphisms (SNP) within the MnSOD encoding gene may be relevant for ROS detoxification. Specifically, the MnSOD Ala16Val SNP has been shown to alter the enzyme localization and mitochondrial transportation, affecting the redox status balance. Oxidative stress may contribute to the development of type 2 diabetes, cardiovascular diseases, various inflammatory conditions, or cancer. The Ala16Val MnSOD SNP has been associated with these and other chronic diseases; however, inconsistent findings between studies have made difficult drawing definitive conclusions. Environmental factors, such as dietary antioxidant intake and exercise have been shown to affect ROS metabolism through antioxidant enzyme regulation and may contribute to explain inconsistencies in the literature. Nevertheless, whether environmental factors may be associated to the Ala16Val genotypes in human diseases still needs to be clarified.

Low catalase activity in blood is associated with the diabetes caused by alloxan

BACKGROUND

Hydrogen peroxide is enzymatically processed by catalase, and catalase deficiency in blood is known as acatalasemia. We examined whether low catalase activity is a risk factor for diabetes mellitus.

METHODS

Blood glucose, insulin and glucose tolerance test were examined in acatalasemic and normal mice under non-stress and oxidative stress conditions. Alloxan administration was used as oxidative stress.

RESULTS

Alloxan, which was a drug that caused diabetes mellitus, mostly generated hydrogen peroxide by the reaction of alloxan and reduced glutathione, in vitro. Incidence of hyperglycemia in alloxan-untreated acatalasemic mice was as low as that in the normal mice. However, the incidence of acatalasemia mice treated with alloxan was higher than that in normal mice, and the number of pancreatic beta-cells in the acatalasemic mice was less than that in normal mice.

CONCLUSION

These results indicate that low catalase activity in the blood is associated with the diabetes mellitus caused by alloxan administration.

Evolution of catalases from bacteria to humans

Excessive hydrogen peroxide is harmful for almost all cell components, so its rapid and efficient removal is of essential importance for aerobically living organisms. Conversely, hydrogen peroxide acts as a second messenger in signal-transduction pathways. H(2)O(2) is degraded by peroxidases and catalases, the latter being able both to reduce H(2)O(2) to water and to oxidize it to molecular oxygen. Nature has evolved three protein families that are able to catalyze this dismutation at reasonable rates. Two of the protein families are heme enzymes: typical catalases and catalase-peroxidases. Typical catalases comprise the most abundant group found in Eubacteria, Archaeabacteria, Protista, Fungi, Plantae, and Animalia, whereas catalase-peroxidases are not found in plants and animals and exhibit both catalatic and peroxidatic activities. The third group is a minor bacterial protein family with a dimanganese active site called manganese catalases. Although catalyzing the same reaction (2 H(2)O(2)--> 2 H(2)O+ O(2)), the three groups differ significantly in their overall and active-site architecture and the mechanism of reaction. Here, we present an overview of the distribution, phylogeny, structure, and function of these enzymes. Additionally, we report about their physiologic role, response to oxidative stress, and about diseases related to catalase deficiency in humans.

Catalase deficiency may complicate urate oxidase (rasburicase) therapy

Patients with low (inherited and acquired) catalase activities who are treated with infusion of uric acid oxidase because they are at risk of tumour lysis syndrome may experience very high concentrations of hydrogen peroxide. They may suffer from methemoglobinaemia and haemolytic anaemia which may be attributed either to deficiency of glucose-6-phosphate dehydrogenase or to other unknown circumstances. Data have not been reported from catalase deficient patients who were treated with uric acid oxidase. It may be hypothesized that their decreased blood catalase could lead to the increased concentration of hydrogen peroxide which may cause haemolysis and formation of methemoglobin. Blood catalase activity should be measured for patients at risk of tumour lysis syndrome prior to uric acid oxidase treatment.

Characterization of acatalasemic erythrocytes treated with low and high dose hydrogen peroxide. Hemolysis and aggregation

The effects of hydrogen peroxide on normal and acatalasemic erythrocytes were examined. Severe hemolysis of acatalasemic erythrocytes and a small tyrosine radical signal (g = 2.005) associated with the formation of ferryl hemoglobin were observed upon the addition of less than 0.25 mM hydrogen peroxide. However, when the concentration of hydrogen peroxide was increased to 0.5 mM, acatalasemic erythrocytes became insoluble in water and increased the tyrosine radical signal. Polymerization of hemoglobin and aggregation of the erythrocytes were observed. On the other hand, normal erythrocytes exhibited only mild hemolysis by the addition of hydrogen peroxide under similar conditions. From these results, the scavenging of hydrogen peroxide by hemoglobin generates the ferryl hemoglobin species (H-Hb-Fe(IV)=O) plus protein-based radicals (*Hb-Fe(IV)=O). These species induce hemolysis of erythrocytes, polymerization of hemoglobin, and aggregation of the acatalasemic erythrocytes. A mechanism for the onset of Takarara disease is proposed.

Simple PCR heteroduplex, SSCP mutation screening methods for the detection of novel catalase mutations in Hungarian patients with type 2 diabetes mellitus

BACKGROUND

The enzyme catalase is the main regulator of hydrogen peroxide metabolism. Deficiency of catalase may cause high concentrations of hydrogen peroxide and increase the risk of the development of pathologies for which oxidative stress is a contributing factor, for example, type 2 diabetes mellitus. Catalase deficiency has been reported to be associated with increased frequency of diabetes mellitus in a cohort of patients in Hungary. In this cohort, the majority of mutations in the catalase gene occur in exon 2.

METHODS

Type 2 diabetic patients (n=308) were evaluated for mutations in intron 1 (81 bp), exon 2 (172 bp) and intron 2 (13 bp) of the catalase gene. Screening for mutations utilized PCR single-strand conformational polymorphism (SSCP) and PCR heteroduplex methods. Verification of detected mutations was by nucleotide sequence analysis.

RESULTS

A total of 11 catalase gene mutations were detected in the 308 subjects (3.57%, p<0.001). Five of the 11 were at two previously reported mutation sites: exon 2 (79) G insertion and (138) GA insertion. Six of the 11 were at five previously unreported catalase mutation sites: intron 1 (60) G-->T; intron 2 (7) G-->A and (5) G-->C; exon 2 (96) T-->A; and exon 2 (135) T-->A. The novel missense mutations on exon 2 (96 and 135) are associated with 59% and 48% decreased catalase activity, respectively; the novel G-->C mutation on intron 2 (5) is associated with a 62% decrease in catalase activity. Mutations detected on intron 1 (60) and intron 2 (7) showed no change in catalase activity. The G-->C mutation on intron 2 (5) might be a splicing mutation. The two missense mutations on exon 2 (96) and (135) cause substitutions of amino acids 53 (Asp-->Glu) and 66 (Glu-->Cys) of the catalase protein. These are close to amino acids that are important for the binding of heme to catalase, 44 (Val) and 72-75 (Arg, Val, Val, His). Changes in heme binding may be responsible for the activity losses.

CONCLUSION

Mutations that cause decreased catalase activity may contribute to susceptibility to inherited type 2 diabetes mellitus. Exon 2 and neighboring introns of the catalase gene may be minor hot spots for type 2 diabetes mellitus susceptibility mutations.

Oxidant and antioxidant balance in the airways and airway diseases

Although oxygen is a prerequisite to life, at concentrations beyond the physiological limits it may be hazardous to the cells. Since the lungs are directly exposed to very high amounts of oxygen, it is imperative for the organ to possess defences against possible oxidative challenge. The lungs are therefore endowed with an armamentarium of a battery of endogenous agents called antioxidants. The antioxidant species help the lungs ward off the deleterious consequences of a wide variety of oxidants/reactive oxygen species such as superoxide anion, hydroxyl radical, hypohalite radical, hydrogen peroxide and reactive nitrogen species such as nitric oxide, peroxynitrite, nitrite produced endogenously and sometimes accessed through exposure to the environment. The major non-enzymatic antioxidants of the lungs are glutathione, vitamins C and E, beta-carotene, uric acid and the enzymatic antioxidants are superoxide dismutases, catalase and peroxidases. These antioxidants are the first lines of defence against the oxidants and usually act at a gross level. Recent insights into cellular redox chemistry have revealed the presence of certain specialized proteins such as peroxiredoxins, thioredoxins, glutaredoxins, heme oxygenases and reductases, which are involved in cellular adaptation and protection against an oxidative assault. These molecules usually exert their action at a more subtle level of cellular signaling processes. Aberrations in oxidant: antioxidant balance can lead to a variety of airway diseases, such as asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis which is the topic of discussion in this review.

Detection of a novel familial catalase mutation (Hungarian type D) and the possible risk of inherited catalase deficiency for diabetes mellitus

The enzyme catalase is the main regulator of hydrogen peroxide metabolism. Recent findings suggest that a low concentration of hydrogen peroxide may act as a messenger in some signalling pathways whereas high concentrations are toxic for many cells and cell components. Acatalasemia is a genetically heterogeneous condition with a worldwide distribution. Yet only two Japanese and three Hungarian syndrome-causing mutations have been reported. A large-scale (23 130 subjects) catalase screening program in Hungary yielded 12 hypocatalasemic families. The V family with four hypocatalasemics (60.6 +/- 7.6 MU/L) and six normocatalasemic (103.6 +/- 23.5 MU/L) members was examined to define the mutation causing the syndrome. Mutation screening yielded four novel polymorphisms. Of these, three intron sequence variations, namely G-->A at the nucleotide 60 position in intron 1, T-->A at position 11 in intron 2, and G-->T at position 31 in intron 12, are unlikely to be responsible for the decreased blood catalase activity. However, the novel G-->A mutation in exon 9 changes the essential amino acid Arg 354 to Cys 354 and may indeed be responsible for the decreased catalase activity. This inherited catalase deficiency, by inducing an increased hydrogen peroxide steady-state concentration in vivo, may be involved in the early manifestation of type 2 diabetes mellitus for the 35-year old proband.

Catalase enzyme mutations and their association with diseases

Enzyme catalase seems to be the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide at high concentrations is a toxic agent, while at low concentrations it appears to modulate some physiological processes such as signaling in cell proliferation, apoptosis, carbohydrate metabolism, and platelet activation. Benign catalase gene mutations of 5' noncoding region (15) and intron 1 (4) have no effect on catalase activity and are not associated with disease. Catalase gene mutations have been detected in association with diabetes mellitus, hypertension, and vitiligo. Decreases in catalase activity in patients with tumors is more likely to be due to decreased enzyme synthesis rather than to catalase mutations.Acatalasemia, the inherited deficiency of catalase has been detected in 11 countries. Its clinical features might be oral gangrene, altered lipid, carbohydrate, homocysteine metabolism and the increased risk of diabetes mellitus. The Japanese, Swiss, and Hungarian types of acatalasemia display differences in biochemical and genetic aspects. However, there are only limited reports on the syndrome causing these mutations. These data show that acatalasemia may be a syndrome with clinical, biochemical, genetic characteristics rather than just a simple enzyme deficiency.

Oxidative Enzymopathies and Vascular Disease

In the vasculature, reactive oxygen species (ROS) generated by both mitochondrial respiration and enzymatic sources serve as integral components of cellular signaling and homeostatic mechanisms. Because ROS are highly reactive biomolecules, the cellular redox milieu is carefully maintained by small-molecule antioxidants and antioxidant enzymes to prevent the deleterious consequences of ROS excess. When this redox balance is perturbed, because of either increased ROS production or decreased antioxidant capacity, oxidant stress is increased in the vessel wall and, if not offset, vascular dysfunction ensues. A number of heritable polymorphisms of pro-oxidant enzymes, including 5-lipoxygenase, cyclooxygenase-2, nitric oxide synthase-3, and NAD(P)H oxidase, have been identified and found to modulate ROS production and, thereby, the risk of atherothrombotic cardiovascular disease in individuals with these genetic polymorphisms. Similarly, heritable deficiency of the antioxidant enzymes catalase, glutathione peroxidases, glutathione- S -transferases, heme oxygenase, and glucose-6-phosphate dehydrogenase favors ROS accumulation, and has been associated with an increased risk of vascular disease. Individually, each of these polymorphisms imposes a state of uncompensated oxidant stress on the vasculature and collectively comprise the oxidative enzymopathies.

The Catalase -262C/T Promoter Polymorphism and Aging Phenotypes

A low level of the central antioxidant enzyme catalase has been suggested to be a risk factor for diseases influenced by oxidative stress. In this study, we investigated the possible association of the catalase -262C/T polymorphism with survival, physical and cognitive functioning, and a number of oxidative stress-mediated disorders. The study population was 2223 Danish individuals, aged 45-93 years, drawn from three population-based surveys. The results suggest that the catalase -262C/T polymorphism is not associated with either survival, or the majority of the age-related phenotypes investigated. However, our data indicate a statistical significant association of TT homozygosity with improved physical functioning as well as a trend of the T allele conferring an improved general cognitive functioning, although these results did not remain significant after correcting for multiple testing. The results raise the hypothesis that the catalase -262T allele serves as protection against neurodegenerative and physical decline, although replication in other studies is warranted for confirmation of these findings.

Phenotypic variability (heterogeneity) of peroxisomal disorders

Peroxisomes perform a multitude of biosynthetic and catabolic functions, many of which are related to lipid metabolism. Peroxisomal disorders result either from deficiency of a single peroxisomal enzyme or protein, or from a defect in the complex mechanism of peroxisomal biogenesis, resulting in deficiency of several or multiple peroxisomal functions. These can be assessed by a battery of biochemical assays, enabling a biochemical phenotype to be defined that is specific and diagnostic for each of the peroxisomal disorders. Some peroxisomal disorders have unique and specific clinical phenotypes, which may be diagnostic. Others share patterns of clinical abnormalities (particularly neurological dysfunction, craniofacial dysmorphism, skeletal defects, sensory deafness, retinopathy) consistent with defined clinical phenotypes, but with considerable overlap and heterogeneity. To a certain extent, the clinical features of a particular disorder reflect the accumulation or deficiency of specific metabolites. Thus, the same clinical phenotypes may be caused by both single enzyme defects and PBDs. Furthermore, the same defect may present with different clinical phenotypes. In general, the severity of the clinical phenotype correlates with the degree of biochemical dysfunction. The clinical heterogeneity of peroxisomal disorders constitutes a diagnostic challenge demanding a high index of suspicion on the clinician's part.

Acatalasemia sensitizes renal tubular epithelial cells to apoptosis and exacerbates renal fibrosis after unilateral ureteral obstruction

Tissue homeostasis is determined by the balance between oxidants and antioxidants. Catalase is an important antioxidant enzyme regulating the level of intracellular hydrogen peroxide and hydroxyl radicals. The effect of catalase deficiency on renal tubulointerstitial injury induced by unilateral ureteral obstruction (UUO) has been studied in homozygous acatalasemic mutant mice (C3H/AnLCsbCsb) compared with wild-type mice (C3H/AnLCsaCsa). Complete UUO caused interstitial cell infiltration, tubular dilation and atrophy, and interstitial fibrosis with accumulation of type IV collagen in obstructed kidneys (OBK) of both mouse groups. However, the degree of injury showed a significant increase in OBK of acatalasemic mice compared with that of wild-type mice until day 7. The deposition of lipid peroxidation products including 4-hydroxy-2-hexenal, malondialdehyde, and 4-hydroxy-2-nonenal was severer in dilated tubules of acatalasemic OBK. Apoptosis in tubular epithelial cells significantly increased in acatalasemic OBK at day 4. Expression of caspase-9, a marker of mitochondrial pathway-derived apoptosis, increased in dilated tubules of acatalasemic mice. The level of catalase activity remained low in acatalasemic OBK until day 7 without compensatory upregulation of glutathione peroxidase activity. The data indicate that acatalasemia exacerbated oxidation of renal tissue and sensitized tubular epithelial cells to apoptosis in OBK of UUO. This study demonstrates that catalase deficiency enhanced tubulointerstitial injury and fibrosis in a murine model of UUO and thus supports the protective role of catalase in this model.

The effects of hydrogen peroxide promoted by homocysteine and inherited catalase deficiency on human hypocatalasemic patients

Elevated plasma homocysteine can generate oxygen free radicals and hydrogen peroxide. The enzyme catalase is involved in the protection against hydrogen peroxide. We examined the effect of oxidative stress promoted by homocysteine on erythrocyte metabolism (blood hemoglobin, MCV, folate, B12, serum LDH, LDH isoenzymes, haptoglobin) in the oxidative stress sensitive Hungarian patients with inherited catalase deficiency. The plasma homocysteine (HPLC method, Bio-Rad), folate, B12 (capture binding assay, Abbott), blood hemoglobin concentrations, blood catalase activity (spectrophotometric assay of hydrogen peroxide), and MCV values were determined in 7 hypocatalasemic families including hypocatalasemic (male:12, female:18) patients and their results were compared to those of the normocatalasemic (male:17 female: 12) family members. We found decreased (p <.036) folate (ng/ml) concentrations (male hypocatalasemic 5.44 +/- 2.81 vs. normocatalasemic 7.56 +/- 1.97, female 5.01 +/- 1.93 vs. 6.61 +/- 1.91), blood hemoglobin (p <.010, male:140.2 +/- 11.0 vs. 153.6 +/- 11.6 g/l, female: 128.4 +/- 10.9 vs. 139.6 +/- 9.2 g/l). Increased levels of MCV (p <.001) were detected in hypocatalasemic patients (male: 98.6 +/- 3.4 vs. 90.1 +/- 7.5 fl, female: 95.9 +/- 3.9 vs. 90.1 +/- 2.5 fl), plasma homocysteine (p <.049, male: 9.72 +/- 3.61 vs. 7.36 +/- 2.10 umol/l, female: 9.06 +/- 3.10 vs. 6.84 +/- 2.50 umol/l) and not significant (p >.401) plasma B12 (male: 336 +/- 108 vs. 307 +/- 76 pg/ml, female: 373 +/- 180 vs. 342 +/- 75 pg/ml). The serum markers of hemolysis (LDH, LDH isoenzymes, haptoglobin) did not show significant (p >.228) signs of oxidative erythrocyte damage. We report firstly on increased plasma homocysteine concentrations in inherited catalase deficiency. The increased plasma homocysteine and inherited catalase deficiency together could promote oxidative stress via hydrogen peroxide. The patients with inherited catalase deficiency are more sensitive to oxidative stress of hydrogen peroxide than the normocatalasemic family members. This oxidative stress might be responsible for the decreased concentration of the blood hemoglobin via the oxidation sensitive folate and may contribute to the early development of arteriosclerosis and diabetes in these patients.

Antioxidant enzyme expression in health and disease: effects of exercise and hypertension

Antioxidant enzymes (superoxide dismutases, catalase and glutathione peroxidase) are components of an organism's mechanisms for combating oxidative stress which is generated in normal metabolism and which may also be a reaction in response to external stimuli. This review identifies the general significance of antioxidant enzymes in health and disease, and some of the diseases that are now believed to have oxidative stress as a component. A discussion is then presented of the molecular mechanisms by which antioxidant enzyme expression is controlled at the transcriptional and post-transcriptional levels. The final sections of the review highlight the effects of exercise and hypertension on antioxidant enzyme expression in a number of different tissues, and the possibilities for future studies in these areas are discussed.