Influence of human haptoglobin polymorphism on oxidative stress induced by free hemoglobin on red blood cells

Association of Haptoglobin Phenotypes with Outcomes in Patients with Spontaneous Intracerebral Hemorrhage

Object. We aimed to investigate the association of Haptoglobin (Hp) phenotypes with perihematomal edema (PHE) and neurological outcomes after intracerebral hemorrhage (ICH). Methods. This prospective multicenter study enrolled patients that suffered ICH from March 2017 to February 2020. Hp phenotypes were determined using Western blotting; relative α1 intensity was calculated in patients with Hp2-1. A multivariable logistic regression analysis was then conducted to identify risk factors for increased relative PHE at 96 h and 3-month poor outcomes. Results. In total, 120 patients were ultimately enrolled: Hp1-1 (n = 15, 12.5%); Hp2-1 (n = 51, 42.5%); and Hp2-2 (n = 54, 45.0%). Hp phenotype was significantly associated with PHE (p = 0.028). With Hp1-1 as a reference value, Hp2-2 significantly increased the likelihood of increased rPHE (OR = 6.294, 95% CI: 1.283–30.881), while Hp2-1 did not (OR = 2.843, 95% CI: 0.566–14.284). Poor outcomes were found to be closely associated with hematoma volume at admission (OR = 1.057, 95% CI: 1.015–1.101) and surgical treatment (OR = 5.340, 95% CI: 1.665–17.122) but not Hp phenotypes (p = 0.190). Further, a high level of relative α1 intensity was identified to be significantly associated with decreased rPHE (OR = 0.020, 95% CI: 0.001–0.358). However, the relative α1 intensity was not associated with poor outcomes (OR = 0.057, 95% CI: 0.001–11.790). Conclusions: ICH patients with Hp2-2 exhibited a higher likelihood of increased rPHE than those with Hp1-1. Higher relative α1 intensities were identified to be closely associated with rPHE in patients with Hp2-1.

Association of Haptoglobin Phenotype With Neurological and Cognitive Outcomes in Patients With Subarachnoid Hemorrhage

Background

To assess the association of haptoglobin (Hp) phenotype with neurological and cognitive outcomes in a large cohort of patients with subarachnoid hemorrhage (SAH).

Methods

This prospective multicenter study enrolled patients with aneurysmal SAH between May 2015 and September 2020. The Hp phenotype was confirmed via Western blots. The relative intensities of α1 in individuals carrying Hp2-1 were compared with those of albumin. Multivariable logistic and Cox proportional-hazard regression analyses were used to identify the risk factors for 6-month and long-term outcomes, respectively.

Results

A total of 336 patients including the phenotypes Hp1-1 (n = 31, 9.2%), Hp2-1 (n = 126, 37.5%), and Hp2-2 (n = 179, 53.3%) were analyzed. The Hp phenotype was closely associated with 6-month outcome (p = 0.001) and cognitive function (p = 0.013), and long-term outcome (p = 0.002) and cognitive function (p < 0.001). Compared with Hp1-1 as the reference value, Hp2-2 significantly increased the risk of 6-month poor outcome (OR: 7.868, 95% CI: 1.764–35.093) and cognitive impairment (OR: 8.056, 95% CI: 1.020–63.616), and long-term poor outcome (HR: 5.802, 95% CI: 1.795–18.754) and cognitive impairment (HR: 7.434, 95% CI: 2.264–24.409). Long-term cognitive impairment based on the Hp phenotype was significantly higher in patients under 65 years of age (p < 0.001) and female gender (p < 0.001). A lower relative α1/albumin intensity (OR: 0.010, 95% CI: 0.000–0.522) was associated with poor outcome at 6 months but not cognitive impairment in patients with SAH expressing Hp2-1.

Conclusion

Hp2-2 increased the risk of poor neurological outcomes and cognitive impairment compared with Hp1-1. For Hp2-1, higher relative α1 intensities were related to 6-month favorable outcomes.

Proteome dynasmics and bioinformatics reveal major alterations in the turnover rate of functionally related cardiac and plasma proteins in a dog model of congestive heart failure

Protein pool turnover is a critically important cellular homeostatic component, yet it has been little explored in the context of heart failure (HF) pathophysiology. We employed in vivo ²H labeling/ proteome dynamics for non-biased discovery of turnover alterations involving functionally linked cardiac and plasma proteins in canine tachypacing-induced HF, an established preclinical model of dilated cardiomyopathy. Compared to control, dogs with congestive HF displayed bidirectional turnover changes of 28 cardiac proteins, i.e. reduced half-life of several key enzymes involved in glycolysis, homocysteine metabolism and glycogenesis, and increased half-life of proteins involved in proteolysis. Changes in plasma proteins were more modest: only 5 proteins, involved in various functions including proteolysis inhibition, hemoglobin, calcium and ferric-iron binding, displayed increased or decreased turnover rates. In other dogs undergoing cardiac tachypacing, we infused for 2 weeks the myokine Follistatin-like protein 1 (FSTL1), known for its ameliorative effects on HF-induced alterations. Proteome dynamics proved very sensitive in detecting the partial or complete prevention, by FSTL1, of cardiac and plasma protein turnover alterations. In conclusion, our study unveiled, for the first time in a large mammal, numerous HF-related alterations that may serve as the basis for future mechanistic research and/or as conceptually new molecular markers.

Heme Degradation in Pathophysiology of and Countermeasures to Inflammation-Associated Disease

The class of tetrapyrrol "coordination complexes" called hemes are prosthetic group components of metalloproteins including hemoglobin, which provide functionality to these physiologically essential macromolecules by reversibly binding diatomic gasses, notably O₂, which complexes to ferrous (reduced/Fe(II)) iron within the heme porphyrin ring of hemoglobin in a pH- and PCO₂-dependent manner-thus allowing their transport and delivery to anatomic sites of their function. Here, pathologies associated with aberrant heme degradation are explored in the context of their underlying mechanisms and emerging medical countermeasures developed using heme oxygenase (HO), its major degradative enzyme and bioactive metabolites produced by HO activity. Tissue deposits of heme accumulate as a result of the removal of senescent or damaged erythrocytes from circulation by splenic macrophages, which destroy the cells and internal proteins, including hemoglobin, leaving free heme to accumulate, posing a significant toxicogenic challenge. In humans, HO uses NADPH as a reducing agent, along with molecular oxygen, to degrade heme into carbon monoxide (CO), free ferrous iron (FeII), which is sequestered by ferritin protein, and biliverdin, subsequently metabolized to bilirubin, a potent inhibitor of oxidative stress-mediated tissue damage. CO acts as a cellular messenger and augments vasodilation. Nevertheless, disease- or trauma-associated oxidative stressors sufficiently intense to overwhelm HO may trigger or exacerbate a wide range of diseases, including cardiovascular and neurologic syndromes. Here, strategies are described for counteracting the effects of aberrant heme degradation, with a particular focus on "bioflavonoids" as HO inducers, shown to cause amelioration of severe inflammatory diseases.

Study of Correlation Between Hp α1 Expression of Haptoglobin 2-1 and Clinical Course in Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Haptoglobin (Hp) comprising 2 light (α) and 2 heavy (β) chains has an antioxidant effect following free hemoglobin binding. Among 3 phenotypes-Hp1-1 (two α1), Hp2-1 (α1 and α2), and Hp2-2 (two α2)-a greater protective effect for toxic-free hemoglobin was reported for Hp2-2 compared with Hp1-1. However, few studies have focused on the association of Hp2-1 with outcomes. This study examined α1 and α2 expression, and evaluated the correlation of Hp2-1 with outcomes of subarachnoid hemorrhage (SAH).

METHODS

Eighty-seven patients were enrolled prospectively, including 12 in the Hp1-1 group (13.8%), 36 in the Hp2-1 group (41.4%), and 39 in the Hp2-2 group (44.8%). Phenotypes were confirmed by Western blot analysis. The relative band intensities were measured as α subunit intensities normalized to albumin intensities and expressed as median (interquartile range). The differences in α intensities according to delayed cerebral ischemia (DCI), angiographic vasospasm (AV), and outcome were analyzed.

RESULTS

DCI and AV were more frequently associated with Hp2-2 than with Hp1-1 (DCI: 21 [53.8%] vs. 3 [25.0%]; AV: 22 [56.4%] vs. 3 [25.0%]). The α1 intensities of Hp2-1 without DCI and AV were significantly higher than those with DCI and AV (without DCI: 0.70 [interquartile range (IQR), 0.54-0.89]; with DCI: 0.24 [IQR, 0.14-0.32]; P < 0.001; without AV: 0.65 [IQR, 0.32-0.88]; with AV: 0.32 [IQR, 0.17-0.67]; P = 0.046). No significant difference was noted with α2 intensities. The α1 (P = 0.359) and α2 (P = 0.233) intensities did not differ significantly according to outcome.

CONCLUSIONS

Higher α1 intensities in Hp2-1 are associated with a lower risk of DCI and AV. The degree of α1 intensity may provide additional information about the individual risk of secondary injury following SAH in patients with Hp2-1.

Association between haptoglobin gene and insulin resistance in Arab-Americans

AIM

To analyze associations between variation in the HP gene and lipid and glucose-related measures in Arab-Americans. Secondary analyses were performed based on sex.

PATIENTS & METHODS

Genomic DNA was extracted from samples obtained from a previous epidemiological study of diabetes in Arab-Americans. The HP 1 and 2 alleles were analyzed by polymerase chain reaction and gel electrophoresis. Associations were analyzed by linear regression.

RESULTS & CONCLUSION

Associations were identified between the heterozygous haptoglobin 2-1 genotype and insulin resistance, fasting insulin and fasting c-peptide. The effect of sex did not remain significant after adjustment for relevant variables. HP genetic variation may have utility as a biomarker of insulin resistance and diabetes risk in Arab-Americans, however, future prospective studies are needed.

The role of haptoglobin genotypes in Chagas disease

Although the number of people infected with T. cruzi is on the rise, host genetic and immune components that are crucial in the development of the Chagas disease have been discovered. We investigated the frequency of polymorphisms in the gene encoding haptoglobin of patients with chronic Chagas disease. The results suggest that while the HP1-1 genotype may confer protection against infection and the development of chronic Chagas disease due to the rapid metabolism of the Hp1-1-Hb complex and its anti-inflammatory activity, the presence of HP2-2 genotype may increase susceptibility towards a chronic condition of the disease due to a slow metabolism of the Hp2-2-Hb complex, lower antioxidant activity, and increased inflammatory reactivity, which lead to cell damage and a deterioration of the cardiac function. Finally, correlations between HP genotypes in different age groups and cardiac manifestations suggest that HP polymorphism could influence the prognosis of this infectious disease. This study shows some of the relevant aspects of the haptoglobin gene polymorphism and its implications in the T. cruzi infection.

Haptoglobin genotype and risk markers of cardiovascular disease in patients with chronic kidney disease

Sudden cardiac death and atherosclerosis have a major impact on cardiovascular mortality in chronic kidney disease (CKD). Inflammation with elevated high-sensitive C-reactive protein (hs-CRP) is involved in both sudden cardiac death and atherosclerosis, and decreased heart rate variability (HRV) is a predictor of both sudden cardiac death and atherosclerosis. Haptoglobin (Hp) is characterised by three genotypes (1-1, 2-1, and 2-2) with different antioxidant abilities. The aim was to examine whether HRV and hs-CRP were associated with Hp genotype in CKD patients. Fifty-six patients with CKD stage 2-5 were included. Hp genotype was determined by high-performance liquid chromatography. HRV was analysed from the 24 h Holter recordings. Hs-CRP was measured using an immunoturbidimetric assay. The results show that the HRV indices SDNN and SDANN were significantly lower in the Hp 2-2 patients (P = 0.02 and 0.04, resp.). In an adjusted linear regression model, Hp 2-2 was associated with both SDNN (P = 0.005) and SDANN (P = 0.01). Hs-CRP was higher in the Hp 2-2 patients (P = 0.002). In an adjusted linear regression model, the association between Hp 2-2 and hs-CRP remained significant (P = 0.003). In conclusion, a negative association was observed between Hp 2-2 and HRV, and Hp 2-2 was positively associated with hs-CRP in CKD patients.

Haptoglobin polymorphism in relation to antioxidative enzymes activity in type 2 diabetes mellitus

BACKGROUND

Increased oxidative stress and impaired antioxidative capacity are common findings in diabetics. This study reports on the status of antioxidative enzymes in relation to haptoglobin (Hp) polymorphism in type 2 diabetes.

METHODS

The study comprised 165 type 2 diabetic patients and 94 controls. Erythrocytic superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT), and plasmatic ceruloplasmin ferroxidase (Cp) were measured by spectrophotometry and Hp phenotypes were determined by gel electrophoresis.

RESULTS

Irrespective of Hp phenotype, while the activities of Cp ferroxidase and GPx were significantly higher in patients than in controls, those of SOD were significantly lower. No significant differences observed for CAT. However, significant Hp-phenotype dependent differences were observed between patients and controls regarding the activity of these enzymes. While ferroxidase activity in Hp2-2 patients was significantly higher than that in Hp1-1 or Hp2-1 patients, that of SOD and GPx were significantly lower. When patients were analyzed as a single group, Spearman's univariate analysis has demonstrated that HbA1c positively correlates with ferroxidase activity and negatively correlates with levels of GPx and SOD. However, when patients were treated as separate Hp-dependent groups, similar but stronger correlations between these variable were noted only in the case of Hp2-2 patients.

CONCLUSIONS

These findings suggest that Hp polymorphism has some bearing on the activity of antioxidative enzymes in type 2 diabetes and that Hp2-2 diabetics are under increased oxidative stress as compared with those expressing Hp1-1 or Hp2-1.

Protein antioxidants in thalassemia

It is common knowledge that thalassemic patients are under significant oxidative stress. Chronic hemolysis, frequent blood transfusion, and increased intestinal absorption of iron are the main factors that result in iron overload with its subsequent pathophysiologic complications. Iron overload frequently associates with the generation of redox-reactive labile iron, which in turn promotes the production of other reactive oxygen species (ROS). If not neutralized, uncontrolled production of ROS often leads to damage of various intra- and extracellular components such as DNA, proteins, lipids, and small antioxidant molecules among others. A number of endogenous and exogenous defense mechanisms can neutralize and counteract the damaging effects of labile iron and the reactive substances associated with it. Endogenous antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and ferroxidase, may directly or sequentially terminate the activities of ROS. Nonenzymatic endogenous defense mechanisms include metal binding proteins (ceruloplasmin, haptoglobin, albumin, and others) and endogenously produced free radical scavengers (glutathione (GSH), ubiquinols, and uric acid). Exogenous agents that are known to function as antioxidants (vitamins C and E, selenium, and zinc) are mostly diet-derived. In this review, we explore recent findings related to various antioxidative mechanisms operative in thalassemic patients with special emphasis on protein antioxidants.

Quantitative mass spectrometry defines an oxidative hotspot in hemoglobin that is specifically protected by haptoglobin

The reaction of hemoglobin (Hb) with hydrogen peroxide (H(2)O(2)) results in free radicals generated at the heme iron, followed by radical transfer to the porphyrin/globin. In the present work, we employed isobaric tagging for relative and absolute quantification (iTRAQ) and a LC-MALDI-MS/MS-based proteomic approach to identify the extent of oxidative changes within tetrameric Hb and dimeric Hb-haptoglobin (Hb-Hp) complexes. Extensive oxidative modifications were found to be restricted to peptides containing alphaTyr42, betaTyr145, and betaCys93. The protein region composed of these peptides appears to define an area of oxidative activity within the Hb tetramer that extends across the critical alpha1beta2/alpha2beta1 interface. Extensive oxidative modifications occurring at betaCys93 indicate that this surface amino acid is an important end point for free radical induced protein oxidation within Hb. Conversely when Hp 1-1 or 2-2 was complexed with dissociable Hb, oxidative changes in Hp complexed dimeric Hb were prevented. This protection was not observed in a stabilized tetrameric Hb, which displays a weak binding affinity for Hp. Therefore, dimerization of Hb and Hp binding may interfere with free radical translocation and play an important role in the overall antioxidant mechanism of Hp. Interestingly, the prevention of peroxide induced Hb amino acid oxidation in purified Hb-Hp1-1 and Hb-Hp2-2 was found to be equal, indicating a phenotype independent specificity in the process of oxidative protection. Taken together, these data suggest differences in oxidative modifications resulting from peroxide induced heme emanated free radical distribution in tetrameric compared to Hp1-1/Hp2-2 stabilized dimeric Hb.

Cytochrome P450 regulation: the interplay between its heme and apoprotein moieties in synthesis, assembly, repair, and disposal

Heme is vital to our aerobic universe. Heme cellular content is finely tuned through an exquisite control of synthesis and degradation. Heme deficiency is deleterious to cells, whereas excess heme is toxic. Most of the cellular heme serves as the prosthetic moiety of functionally diverse hemoproteins, including cytochromes P450 (P450s). In the liver, P450s are its major consumers, with >50% of hepatic heme committed to their synthesis. Prosthetic heme is the sine qua non of P450 catalytic biotransformation of both endo- and xenobiotics. This well-recognized functional role notwithstanding, heme also regulates P450 protein synthesis, assembly, repair, and disposal. These less well-appreciated aspects are reviewed herein.

Haptoglobin polymorphism and infection

The haptoglobin gene is highly polymorphic in humans with strong evidence of functionally distinct biochemical phenotypes. In all human populations, three major haptoglobin phenotypes Hp 1-1, Hp 2-1, and Hp 2-2 are present, but additional phenotypes have been identified. Haptoglobin polymorphism has important biological and clinical significance. In this review, we examine the putative role of haptoglobin polymorphism in parasitic, bacterial, and viral infections. Despite many striking effects of haptoglobin polymorphism in infectious conditions, the effects of haptoglobin genetic variation upon infections are not always predictable due to the multifunctional character of the plasma protein (e.g., antibody-like properties, immunomodulation, iron metabolism). More studies on the interplay of haptoglobin polymorphism, vaccination, and susceptibility or resistance to common infections seem warranted.

Dietary carotenoid-rich oil supplementation improves exercise-induced anisocytosis in runners: influences of haptoglobin, MnSOD (Val9Ala), CAT (21A/T) and GPX1 (Pro198Leu) gene polymorphisms in dilutional pseudoanemia (sports anemia)

Physical training induces beneficial adaptation, whereas exhaustive exercises increase reactive oxygen-species generation, thereby causing oxidative damage in plasma and erythrocytes, fractions susceptible to lipid peroxidation. Pequi (Caryocar brasiliense Camb.) is a Brazilian Cerrado fruit containing a carotenoid-rich oil. The aim was to investigate the effects of pequi-oil on exercise-induced oxidative damage in plasma and erythrocytes, after running in the same environment and undergoing weekly training under the same conditions as to type, intensity and length. Evaluations were accomplished after outdoor running on flat land before and after ingestion of 400 mg pequi-oil capsules for 14 days. Blood samples were taken after running and submitted to TBARS assay and erythrogram analysis. Haptoglobin, MnSOD (Val9Ala), CAT (21A/T) and GPX1 (Pro198Leu) gene polymorphisms were priorly investigated, so as to estimate genetic influence The reduction in erythrocytes, hemoglobin and hematocrit after pequi-oil treatment was notably associated with higher plasma expansion. Except for MCHC (mean corpuscular hemoglobin concentration) and RDW (red cell distribution width), the results were influenced by the polymorphisms studied. The best response to pequi-oil was presented by MnSOD Val/Val, CAT AA or AT genotypes and the GPX1 Pro allele. The significantly lower RDW and higher MHCH values were related to pequi-oil protective effects. Pequi oil, besides possessing other nutritional properties, showed protective blood effects.

Evaluation of gene polymorphisms in exercise-induced oxidative stress and damage

Many potentially significant genetic variants related to oxidative stress have been identified and performance in endurance sports is a multi-factorial phenotype. Thus, it was decided to investigate the influences of the haptoglobin (Hp), MnSOD (Val9Ala), CAT (21A/T), GPX1 (Pro198Leu), ACE, glutathione S-transferases M1 (GSTM1) and T1 (GSTT1) genes' polymorphisms on the oxidative stress and damage suffered by human athletes (runners). Blood samples taken immediately after a race were submitted to genotyping, comet and TBARS assays, biochemical analyses of creatine kinase (CK), aspartate aminotransferase (AST) and alanine aminotransferase (ALT). MnSOD significantly influenced results of CK and a possible association between Hp1F-1S and Hp1S-2 genotypes with a superior TBARS values was found. Higher or lower TBARS and CK values or DNA damage also depended on the interaction between Hp and ACE or GST genotypes, indicating that MnSOD and Hp polymorphisms can be determining factors in performance, at least for runners.

Gene polymorphisms against DNA damage induced by hydrogen peroxide in leukocytes of healthy humans through comet assay: a quasi-experimental study

BACKGROUND

Normal cellular metabolism is well established as the source of endogenous reactive oxygen species which account for the background levels of oxidative DNA damage detected in normal tissue. Hydrogen peroxide imposes an oxidative stress condition on cells that can result in DNA damage, leading to mutagenesis and cell death. Several potentially significant genetic variants related to oxidative stress have already been identified, and angiotensin I-converting enzyme (ACE) inhibitors have been reported as possible antioxidant agents that can reduce vascular oxidative stress in cardiovascular events.

METHODS

We investigate the influences of haptoglobin, manganese superoxide dismutase (MnSOD Val9Ala), catalase (CAT -21A/T), glutathione peroxidase 1 (GPx-1 Pro198Leu), ACE (I/D) and gluthatione S-transferases GSTM1 and GSTT1 gene polymorphisms against DNA damage and oxidative stress. These were induced by exposing leukocytes from peripheral blood of healthy humans (N = 135) to hydrogen peroxide (H2O2), and the effects were tested by comet assay. Blood samples were submitted to genotyping and comet assay (before and after treatment with H2O2 at 250 microM and 1 mM).

RESULTS

After treatment with H2O2 at 250 microM, the GPx-1 polymorphism significantly influenced results of comet assay and a possible association of the Pro/Leu genotype with higher DNA damage was found. The highest or lowest DNA damage also depended on interaction between GPX-1/ACE and Hp/GSTM1T1 polymorphisms when hydrogen peroxide treatment increased oxidative stress.

CONCLUSIONS

The GPx-1 polymorphism and the interactions between GPX-1/ACE and Hp/GSTM1T1 can be determining factors for DNA oxidation provoked by hydrogen peroxide, and thus for higher susceptibility to or protection against oxidative stress suffered by healthy individuals.

Heme degradation and vascular injury

Heme is an essential molecule in aerobic organisms. Heme consists of protoporphyrin IX and a ferrous (Fe(2+)) iron atom, which has high affinity for oxygen (O(2)). Hemoglobin, the major oxygen-carrying protein in blood, is the most abundant heme-protein in animals and humans. Hemoglobin consists of four globin subunits (alpha(2)beta(2)), with each subunit carrying a heme group. Ferrous (Fe(2+)) hemoglobin is easily oxidized in circulation to ferric (Fe(3+)) hemoglobin, which readily releases free hemin. Hemin is hydrophobic and intercalates into cell membranes. Hydrogen peroxide can split the heme ring and release "free" redox-active iron, which catalytically amplifies the production of reactive oxygen species. These oxidants can oxidize lipids, proteins, and DNA; activate cell-signaling pathways and oxidant-sensitive, proinflammatory transcription factors; alter protein expression; perturb membrane channels; and induce apoptosis and cell death. Heme-derived oxidants induce recruitment of leukocytes, platelets, and red blood cells to the vessel wall; oxidize low-density lipoproteins; and consume nitric oxide. Heme metabolism, extracellular and intracellular defenses against heme, and cellular cytoprotective adaptations are emphasized. Sickle cell disease, an archetypal example of hemolysis, heme-induced oxidative stress, and cytoprotective adaptation, is reviewed.

Transcriptomic and genomic evolution under constant cold in Antarctic notothenioid fish

The antifreeze glycoprotein-fortified Antarctic notothenioid fishes comprise the predominant fish suborder in the isolated frigid Southern Ocean. Their ecological success undoubtedly entailed evolutionary acquisition of a full suite of cold-stable functions besides antifreeze protection. Prior studies of adaptive changes in these teleost fishes generally examined a single genotype or phenotype. We report here the genome-wide investigations of transcriptional and genomic changes associated with Antarctic notothenioid cold adaptation. We sequenced and characterized 33,560 ESTs from four tissues of the Antarctic notothenioid Dissostichus mawsoni and derived 3,114 nonredundant protein gene families and their expression profiles. Through comparative analyses of same-tissue transcriptome profiles of D. mawsoni and temperate/tropical teleost fishes, we identified 177 notothenioid protein families that were expressed many fold over the latter, indicating cold-related up-regulation. These up-regulated gene families operate in protein biosynthesis, protein folding and degradation, lipid metabolism, antioxidation, antiapoptosis, innate immunity, choriongenesis, and others, all of recognizable functional importance in mitigating stresses in freezing temperatures during notothenioid life histories. We further examined the genomic and evolutionary bases for this expressional up-regulation by comparative genomic hybridization of DNA from four pairs of Antarctic and basal non-Antarctic notothenioids to 10,700 D. mawsoni cDNA probes and discovered significant to astounding (3- to >300-fold, P < 0.05) Antarctic-specific duplications of 118 protein-coding genes, many of which correspond to the up-regulated gene families. Results of our integrative tripartite study strongly suggest that evolution under constant cold has resulted in dramatic genomic expansions of specific protein gene families, augmenting gene expression and gene functions contributing to physiological fitness of Antarctic notothenioids in freezing polar conditions.

Hemoglobin induces cytotoxic damage of glycine-preserved renal tubules

In isolated tubular segments (ITS) of rat kidney cortex, we studied the effect of hemoglobin (Hb) on reoxygenation damage. All tubules were suspended in Ringer's solution containing 5-mm glycine and oxygenated for 30 min with 95% O(2):5% CO(2), followed by a 30-min period with 95% N(2):5% CO(2), and final reoxygenation for 60 min. Untreated tubules served as controls. Different concentrations of free Hb and equivalent amounts of intact erythrocytes were added to the incubation medium. Secondly, we added deferoxamine (DFO) to Hb and erythrocytes. Membrane leakage and lipid peroxidation were measured by lactate dehydrogenase and glutamate dehydrogenase and the development of thiobarbituric acid reactive substances. Cell function was quantified by gluconeogenesis and intracellular potassium accumulation. Hb exerted concentration-dependent cytotoxic effects indicated by significantly increased enzyme leakage rates, lipid peroxidation and a significantly decreased cell function (P < 0.05), in ITS during hypoxia, and subsequent reoxygenation. Moreover, we found that toxicity of both Fe(2+) and Fe(3+) ions increased with rising concentration. However, Fe(2+) showed a higher tissue toxicity than Fe(3+). DFO reduced significantly the reoxygenation damage of free Hb and iron ions. Our data clearly demonstrate a pronounced cytotoxic effect of free Hb in ITS, which critically depended on the reduction state of the iron ions.

Haptoglobin: a review of the major allele frequencies worldwide and their association with diseases

Haptoglobin (Hp) is a plasma alpha(2)-glycoprotein which binds free haemoglobin, thus preventing oxidative damage. The complex is rapidly removed from the circulation by a specific receptor (CD163) found on macrophages. Three major subtypes, Hp1-1, Hp2-1 and Hp2-2 are the product of two closely related genes HP(1) and HP(2). The frequency of the HP(1) and HP(2) genes varies worldwide depending on racial origin: the HP(1)frequency varying from about 0.07 in parts of India to over 0.7 in parts of West Africa and South America. Both HP(1) and HP(2) have been linked to susceptibility to various diseases. Such associations may be explained by functional differences between the subtypes in the binding of Hb and its rate of clearance from the plasma. However, there are also corresponding negative reports for disease associations. The conflicting evidence on disease association and the lack of association between disease and particular populations, despite the wide range of HP(1) and HP(2) gene frequencies across the world, may indicate that any associations are marginal.