Persistent High Long-term Excess Mortality After Elective AAA Repair Especially in Women: A Large Population-based Study

OBJECTIVE

The aim of this time-trend analysis is to estimate long-term excess mortality and associated cardiovascular risk for abdominal aortic aneurysm (AAA) patients after elective repair while addressing the changes in AAA management and patient selection over time.

BACKGROUND

Despite the intensification of endovascular aneurysm repair and cardiovascular risk management, Swedish population data suggest that AAA patients retain a persistently high long-term mortality after elective repair. The question is whether this reflects suboptimal treatment, a changing patient population over time, or a national phenomenon.

METHODS

Nationwide time-trend analysis including 40,730 patients (87% men) following elective AAA repair between 1995 and 2017. Three timeframes were compared, each reflecting changes in the use of endovascular aneurysm repair and intensification of cardiovascular risk management. Relative survival analyses were used to estimate disease-specific excess mortality. Competing risk of death analysis evaluated the risk of cardiovascular versus noncardiovascular death. Sensitivity analysis evaluated the impact of changes in patient selection over time.

RESULTS

Short-term excess mortality significantly improved over time. Long-term excess mortality remained high with a doubled mortality risk for women (relative excess risk=1.87, 95% CI: 1.73-2.02). Excess mortality did not differ between age categories. The risk of cardiovascular versus noncardiovascular death remained similar over time, with a higher risk of cardiovascular death for women. Changes in patient population (ie, older and more comorbid patients in the latter period) marginally impacted excess mortality (2%).

CONCLUSIONS

Despite changes in AAA care, patients retain a high long-term excess mortality after elective repair with a persistent high cardiovascular mortality risk. In this, a clear sex - but no age - disparity stands out.

Validating human and mouse tissues commonly used in atherosclerosis research with coronary and aortic reference tissue: similarities but profound differences in disease initiation and plaque stability

Objective

Characterization of the atherosclerotic process fully relies on histological evaluation and staging through a consensus grading system. So far, a head-to-head comparison of atherosclerotic process in experimental models and tissue resources commonly applied in atherosclerosis research with the actual human atherosclerotic process is missing.

Material and Methods

Aspects of the atherosclerotic process present in established murine atherosclerosis models and human carotid endarterectomy specimen were systematically graded using the modified American Heart Association histological classification (Virmani classification). Aspects were aligned with the atherosclerotic process observed in human coronary artery and aortic atherosclerosis reference tissues that were available through biobanks based on human tissue/organ donor material.

Results

Apart from absent intraplaque hemorrhages in aortic lesions, the histological characteristics of the different stages of human coronary and aortic atherosclerosis are similar. Carotid endarterectomy samples all represent end-stage "fibrous calcified plaque" lesions, although secondary, progressive, and vulnerable lesions with gross morphologies similar to coronary/aortic lesions occasionally present along the primary lesions. For the murine lesions, clear histological parallels were observed for the intermediate lesion types ("pathological intimal thickening," and "early fibroatheroma"). However, none of the murine lesions studied progressed to an equivalent of late fibroatheroma or beyond. Notable contrasts were observed for disease initiation: whereas disease initiation in humans is characterized by a mesenchymal cell influx in the intima, the earliest murine lesions are exclusively intimal, with subendothelial accumulation foam cells. A mesenchymal (and medial) response are absent. In fact, it is concluded that the stage of "adaptive intimal thickening" is absent in all mouse models included in this study.

Conclusions

The Virmani classification for coronary atherosclerosis can be applied for systematically grading experimental and clinical atherosclerosis. Application of this histological grading tool shows clear parallels for intermediate human and murine atherosclerotic lesions. However, clear contrasts are observed for disease initiation, and late stage atherosclerotic lesions. Carotid endarterectomy all represent end-stage fibrous calcified plaque lesions, although secondary earlier lesions may present in a subset of samples.

Histological evaluation of the aortic wall response following endovascular aneurysm repair and endovascular aneurysm sealing

Objective

The Nellix endovascular aneurysm sealing (EVAS) system was developed as an alternative to conventional endovascular aneurysm repair (EVAR) to minimize endoleaks. A significantly higher failure rate of EVAS may be related to an interaction between the filled endobags and the AAA wall. In general, biological information on aortic remodeling after traditional EVAR is scarce. In this light, we provide here the first histologic evaluation of aneurysm wall morphology after EVAR and EVAS.

Methods

Fourteen histological human wall samples of EVAS and EVAR explantation were systematically analysed. Primary open aorta repair samples were included as reference.

Results

Compared with primary open aortic repair samples, endovascular repair aortic samples were characterized by more pronounced fibrosis, a greater number of ganglionic structures, decreased cellular inflammation, less calcification, and a lower atherosclerotic load. EVAS was specifically associated with the presence of unstructured elastin deposits.

Conclusions

The biological response of the aortic wall after endovascular repair resembles the maturation process of a scar rather than a bona fide healing response. Moreover, the inflammatory response in the aortic wall after placement of endovascular protheses is less prominent than after primary open repair. A specific post-EVAS aortic wall characteristic was unstructured elastin fragments.

Donor characteristics and their impact on kidney transplantation outcomes: Results from two nationwide instrumental variable analyses based on outcomes of donor kidney pairs accepted for transplantation

BACKGROUND

Donor-characteristics and donor characteristics-based decision algorithms are being progressively used in the decision process whether or not to accept an available donor kidney graft for transplantation. While this may improve outcomes, the performance characteristics of the algorithms remains moderate. To estimate the impact of donor factors of grafts accepted for transplantation on transplant outcomes, and to test whether implementation of donor-characteristics-based algorithms in clinical decision-making is justified, we applied an instrumental variable analysis to outcomes for kidney donor pairs transplanted in different individuals.

METHODS

This analysis used (dis)congruent outcomes of kidney donor pairs as an instrument and was based on national transplantation registry data for all donor kidney pairs transplanted in separate individuals in the Netherlands (1990-2018, 2,845 donor pairs), and the United Kingdom (UK, 2000-2018, 11,450 pairs). Incident early graft loss (EGL) was used as the primary discriminatory factor. It was reasoned that a scenario with a dominant impact of donor variables on transplantation outcomes would result in high concordance of EGL in both recipients, whilst dominance of asymmetrical outcomes could indicate a more complex scenario, involving an interaction of donor, procedural and recipient factors.

FINDINGS

Incidences of congruent EGL (Netherlands: 1·2%, UK: 0·7%) were slightly lower than the arithmetical (stochastic) incidences, suggesting that once a graft has been accepted for transplantation, donor factors minimally contribute to incident EGL. A long-term impact of donor factors was explored by comparing outcomes for functional grafts from donor pairs with asymmetrical vs. symmetrical outcomes. Recipient survival was similar for both groups, but a slightly compromised graft survival was observed for grafts with asymmetrical outcomes in the UK cohort: (10-years Hazard Ratio for graft loss: 1·18 [1·03-1·35] p<0·018); and 5 years eGFR (48·6 [48·3-49·0] vs. 46·0 [44·5-47·6] ml/min in the symmetrical outcome group, p<0·001).

INTERPRETATION

Our results suggest that donor factors for kidney grafts deemed acceptable for transplantation impact minimally on transplantation outcomes. A strong reliance on donor factors and/or donor-characteristics-based decision algorithms could result in unjustified rejection of grafts. Future efforts to optimize transplant outcomes should focus on a better understanding of the recipient factors underlying transplant outcomes.

FUNDING

None.

Equivalent Long-term Transplantation Outcomes for Kidneys Donated After Brain Death and Cardiac Death: Conclusions From a Nationwide Evaluation

BACKGROUND

Despite growing waiting lists for renal transplants, hesitations persist with regard to the use of deceased after cardiac death (DCD) renal grafts. We evaluated the outcomes of DCD donations in The Netherlands, the country with the highest proportion of DCD procedures (42.9%) to test whether these hesitations are justified.

METHODS

This study included all procedures with grafts donated after brain death (DBD) (n = 3611) and cardiac death (n = 2711) performed between 2000 and 2017. Transplant outcomes were compared by Kaplan Meier and Cox regression analysis, and factors associated with short (within 90 days of transplantation) and long-term graft loss evaluated in multi-variable analyses.

FINDINGS

Despite higher incidences of early graft loss (+ 50%) and delayed graft function (+ 250%) in DCD grafts, 10-year graft and recipient survival were similar for the two graft types (Combined 10-year graft survival: 73.9% (95% CI: 72.5-75.2), combined recipient survival: 64.5% (95 CI: 63.0-66.0%)). Long-term outcome equivalence was explained by a reduced impact of delayed graft function on DCD graft survival (RR: 0.69 (95% CI: 0.55-0.87), p < 0.001). Mid and long-term graft function (eGFR), and the impact of incident delayed graft function on eGFR were similar for DBD and DCD grafts.

INTERPRETATION

Mid and long term outcomes for DCD grafts are equivalent to DBD kidneys. Poorer short term outcomes are offset by a lesser impact of delayed graft function on DCD graft survival. This nation-wide evaluation does not justify the reluctance to use of DCD renal grafts. A strong focus on short-term outcome neglects the superior recovery potential of DCD grafts.

The Consequences of Real Life Practice of Early Abdominal Aortic Aneurysm Repair: A Cost-Benefit Analysis

BACKGROUND

The reported 54 mm median intervention diameter for endovascular aneurysm repair (EVAR) in the Vascular Quality Initiative and European data from the Pharmaceutical Aneurysm Stabilisation Trial (PHAST) implies that in real life the majority of abdominal aortic aneurysm (AAA) repairs occur at diameters smaller than the consensus intervention threshold of 55 mm. This study explores the potential consequences of this practice.

METHODS

The differences between real life AAA repair and consensus based intervention threshold were explored in reported data from vascular quality initiatives and PHAST. The subsequent consequences of advancement of endovascular aneurysm repair (EVAR) were estimated using a multistate model based on life tables for the EVAR Medicare population.

RESULTS

There appears an approximate 5 mm difference in AAA diameter between real life practice and consensus intervention threshold. Assuming a 2.5 mm annual growth rate, this results in an approximately 2 year advancement of AAA repair. According to the model used, early repair reduces overall small aneurysm patient mortality by 2.3%, it results in 21.9% more EVAR procedures, more EVAR related deaths, and 42.3% and 36.8% more open and endovascular re-interventions, respectively. Cost-benefit estimates imply 482 fewer AAA related deaths, but 140 extra EVAR related deaths for a population of more than 30,000 AAA patients, and a 300 million USD increase in health costs for the 8 year observation period in the Medicare population.

CONCLUSIONS

In the real life situation a large proportion of EVAR procedures appear to occur before reaching the consensus threshold. Although this reduces mortality, it comes at a cost of approximately 1 million USD per prevented rupture related death.

Myostatin mediates abdominal aortic atherosclerosis progression by inducing vascular smooth muscle cell dysfunction and monocyte recruitment

Myostatin (Mstn) is a skeletal muscle growth inhibitor involved in metabolic disorders and heart fibrosis. In this study we sought to verify whether Mstn is also operative in atherosclerosis of abdominal aorta. In human specimens, Mstn expression was almost absent in normal vessels, became detectable in the media of non-progressive lesions and increased with the severity of the damage. In progressive atherosclerotic lesions, Mstn was present in the media, neointima, plaque shoulder and in infiltrating macrophages. Mstn co-localized with α-smooth muscle actin (α-SMA) staining and with some CD45+ cells, indicating Mstn expression in VSMCs and bloodstream-derived leukocytes. In vitro, Mstn was tested in VSMCs and monocytes. In A7r5 VSMCs, Mstn downregulated proliferation and Smoothelin mRNA, induced cytoskeletal rearrangement, increased migratory rate and MCP-1/CCR2 expression. In monocytes (THP-1 cells and human monocytes), Mstn acted as a chemoattractant and increased the MCP-1-dependent chemotaxis, F-actin, α-SMA, MCP-1 and CCR2 expression; in turn, MCP-1 increased Mstn mRNA. Mstn induced JNK phosphorylation both in VSMCs and monocytes. Our results indicate that Mstn is overexpressed in abdominal aortic wall deterioration, affects VSMCs and monocyte biology and sustains a chronic inflammatory milieu. These findings propose to consider Mstn as a new playmaker in atherosclerosis progression.

Succinate Accumulation and Ischemia-Reperfusion Injury: Of Mice but Not Men, a Study in Renal Ischemia-Reperfusion

A recent seminal paper implicated ischemia-related succinate accumulation followed by succinate-driven reactive oxygen species formation as a key driver of ischemia-reperfusion injury. Although the data show that the mechanism is universal for all organs tested (kidney, liver, heart, and brain), a remaining question is to what extent these observations in mice translate to humans. We showed in this study that succinate accumulation is not a universal event during ischemia and does not occur during renal graft procurement; in fact, tissue succinate content progressively decreased with increasing graft ischemia time (p < 0.007). Contrasting responses were also found with respect to mitochondrial susceptibility toward ischemia and reperfusion, with rodent mitochondria robustly resistant toward warm ischemia but human and pig mitochondria highly susceptible to warm ischemia (p < 0.05). These observations suggest that succinate-driven reactive oxygen formation does not occur in the context of kidney transplantation. Moreover, absent allantoin release from the reperfused grafts suggests minimal oxidative stress during clinical reperfusion.

Abstract 63: CXCL8 Signaling Pathways and the Aortic Abdominal Aneurysm: The Oral CXCR2 Antagonist DF2156A Fully Abrogates Aneurysm Formation

An aneurysm of the abdominal aorta (AAA) is part of the atherososclerotic spectrum of diseases. The disease is characterized by a localized dilatation of the infrarenal artery and rupture of the weakened segment is now responsible for more than 15.000 annual deaths in the US alone. The pathology of AAA is complex and poorly understood. It is generally conceived that AAA is characterized by a localized general pro-inflammatory response and an accompanying protease imbalance that is held responsible for the progressive weakening of the aortic wall. The exact inflammatory pathways that drive aneurysm progression and that distinguish AAA from occlusive atherosclerotic disease have not yet been identified. We previously reported a 21-fold increase in CXCL8 mRNA expression and an approx. 300-fold increase in CXCL8 protein levels in human AAA, as compared to human occlusive atherosclerotic disease (p<0.001); suggesting that activation of the CXCL8/CXCR1-2 axis is a distinctive feature of AAA.

We now performed a histological and protein analysis of human AAA and human occlusive atherosoclerotic disease, showing abundant presence of the CXCL8 receptors CXCR1 and 2 as well as increased ERK phosphorylation in AAA. Evaluation on cellular level identified abundant neutrophils (fully absent in atherosoclerosis) as well as increased neovascularization as clear distinctive features of AAA, a finding that is consistent with increased CXCL8 signaling. To test a putative role of CXCL8/CXCR1-2 system in AAA we next tested whether the oral CXCR2 antagonist DF2156A prevents aneurysm formation in the elastase model, a well established model of the disease. This study showed that a once daily dose of 15mg/kg DF2156A fully abrogates aneurysm formation in the elastase model (71.86% aortic diameter growth in 14 days (SEM 4.88) in untreated animals vs. 17.66% growth (SEM 1.71) in animals treated with DF2156A) (p<0.001).

In conclusion, these studies identify activation of the CXCL8/CXCR1-2 pathway as a distinctive feature of AAA and characterize this pathway as a potential target for the stabilization of AAA.

Intramuscular or combined intramuscular/intra-arterial administration of bone marrow mononuclear cells: a clinical trial in patients with advanced limb ischemia

AIM

Recent evidence indicates that bone marrow mononuclear cells (BMC) promote collateral vessel formation in patients with severe peripheral arterial disease (PAD). However, aspects concerning optimal administration mode, durability and long-term safety require consideration. Combined intra-arterial (IA) plus intramuscular (IM) BMC delivery may be more effective than exclusive intramuscular injections. The aim of this study was to evaluate feasibility, safety and effect of exclusive IM versus combined IM+IA delivery of autologous BMC in patients who were not candidates for surgical or endovascular treatment.

METHODS

Twenty-seven patients were treated with either combined IA+IM (N=12) or sole IM (N=15) administration of autologous BMC. Efficacy was assessed after 1, 6 and 12 months. Limb salvage, pain-free walking distance, ankle-brachial pressure index (ABI) and pain scores were evaluated.

RESULTS

There were no adverse reactions related to injection of the cells. Three patients died within the first year of follow-up due to non-procedure related causes. Two patients in the IA+IM group required limb amputation because of ongoing critical ischemia versus 7 patients in the IM group (P=0.17). BMC treatment in the remaining patients resulted in a significant and sustained (>12 months) improvement. Pain-free walking distance improved from 81+/-56 meters at baseline to 257+/-126 meters at t=6 months (P=0.0002). Mean ABI increased 23% after 6 months (P=0.01) and pain score reduced for up to 50% as shown by Brief Pain Inventory (P=0.001).

CONCLUSION

Both IM and combined IM/IA delivery of autologous BMC are safe, and result in relevant and sustained improvement in a considerable proportion of patients with severe PAD who are not amenable for conventional treatment.

Postnatal changes in plasma ceruloplasmin and transferrin antioxidant activities in preterm babies

Postnatal changes in plasma ceruloplasmin ferroxidase and transferrin iron-binding antioxidant activity were studied in 10 healthy preterm babies during the first 6 weeks of life. Ceruloplasmin levels and ceruloplasmin ferroxidase activity were low at birth, remained stable for the first 3 weeks, and increased between 3 and 6 weeks. The transferrin levels were also low at birth, and this finding persisted throughout the 6-week study period. However, although the plasma iron-binding antioxidant activity was correspondingly low at birth, it thereafter rose and remained high. In four cord blood samples, but not in subsequent postnatal samples, peroxidation was actually stimulated in the assay measuring plasma iron-binding antioxidant activity. We have previously shown that this phenomenon is probably due to the presence of non-protein-bound iron.

Vitamin E status in preterm infants: assessment by plasma and erythrocyte vitamin E-lipid ratios and hemolysis tests

BACKGROUND

Vitamin E is an essential component of the antioxidant defenses, but supplementation can have side effects in the preterm infant. Careful monitoring of vitamin E status is thus essential, however no consensus has been reached on the best clinical method.

METHODS

In 47 healthy preterm infants, several methods for assessment of vitamin E status were evaluated: plasma and erythrocyte vitamin E levels were measured, vitamin E lipid ratios were calculated, and two variations of the hydrogen peroxide hemolysis test were conducted.

RESULTS

At birth, the plasma and erythrocyte vitamin E levels were low. After birth, the plasma levels rose gradually, whereas the erythrocyte levels remained low. In contrast, the vitamin E-total-lipid ratio was in the low normal range from birth onwards. Vitamin E-lipid ratios using two lipid components (cholesterol with triglycerides, or cholesterol with phospholipids) or one lipid component (cholesterol) correlated with the vitamin E-total-lipid ratio with a good sensitivity and specificity. The susceptibility of erythrocytes to hydrogen peroxide-induced damage (measured as potassium release or malondialdehyde production) was high at birth and declined after birth. However, this susceptibility did not correlate with plasma or erythrocyte vitamin E levels or vitamin E-total-lipid ratio, and the hydrogen peroxide hemolysis test is not a reliable indicator of vitamin E status in preterm infants.

CONCLUSIONS

Our study indicated that a gold standard for clinical assessment of vitamin E status in preterm infants is yet to be found.

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes in neonatal respiratory distress syndrome

Markers of oxidative stress and antioxidant activity in plasma and erythrocytes were studied for 14 d after birth in infants with neonatal respiratory distress syndrome (n = 9) and controls (n = 36). In plasma, the total radical trapping antioxidant capacity and the chain-breaking antioxidants vitamin C, sulfhydryl groups and bilirubin were similar. The differences in uric acid levels were not consistent, but vitamin E levels and vitamin E/total-lipid ratio were lower in the neonatal respiratory distress group (p < 0.01). In erythrocytes, the antioxidant enzymes glutathione peroxidase, glutathione reductase and superoxide dismutase did not differ postnatally. Indicators of oxidative damage in plasma (sulfhydryl/protein ratio and thiobarbituric acid reactive substances) showed the same postnatal course in both groups and were not influenced by oxygen therapy. In erythrocytes the reduced/oxidized glutathione ratio showed no consistent differences. In conclusion, this study, using erythrocytes and plasma, does not provide convincing evidence of oxidative damage and diminished antioxidant defenses in preterm infants with neonatal respiratory distress syndrome.

Measured versus calculated latent iron binding capacity in plasma of newborns

Iron overload as well as iron deficiency may play a role in the pathogenesis of diseases in the newborn and infant and therefore knowledge of the iron status is essential. Using an automated method for the determination of plasma latent iron-binding capacity (LIBC) we measured the LIBC in 20 full term and 20 preterm babies and 20 adults. LIBC was also calculated from transferrin and iron concentration.

Diminished protection against copper-induced lipid peroxidation by cord blood plasma of preterm and term infants

BACKGROUND

Blood plasma of neonates is less able to inhibit iron induced lipid peroxidation than plasma of older patients. Copper, also a powerful pro-oxidant, may accumulate in ill babies because of excess intake or decreased excretion. We assessed in vitro the ability of plasma of neonates to inhibit copper induced peroxidation damage.

METHODS

Peroxidation of phospholipid liposomes, induced by CuCl2, was measured with a thiobarbituric acid assay. The ability of plasma from venous blood of adults and cord blood of babies to inhibit peroxidation was compared. The levels of the copper binding plasma proteins, albumin and ceruloplasmin, were also measured.

RESULTS

Protection against copper induced lipid peroxidation was much higher with adult plasma compared to neonatal plasma. Despite their lower albumin and ceruloplasma levels the protection by the plasma of preterm babies was higher than that of the term babies.

CONCLUSIONS

At birth, babies have a limited ability to inhibit copper induced oxidative damage in vitro. Postnatal studies are needing to assess the influence of maturation and nutrition on these findings and their relevance in diseases induced by reactive oxygen species.

Postnatal changes in plasma chain-breaking antioxidants in healthy preterm infants fed formula and/or human milk

Concentrations of chain-breaking antioxidants were studied in the first 6 postnatal weeks in 29 healthy preterm infants (gestational age 30-35 wk). Vitamin C, uric acid, and sulfhydryl groups declined, whereas vitamin E rose and bilirubin followed its typical biphasic postnatal course. The influence of these changes on the plasma peroxyl radical trapping capacity was assessed in vitro (TRAP assay). The trapping capacity decreased postnatally and this appeared to be related to the coincident fall in uric acid concentrations. Results did not differ between babies fed with only preterm formula (n = 12) and those fed predominantly with human milk (n = 6), except for higher bilirubin and TRAP values in the breast-fed infants. There are major postnatal changes in the concentrations of the plasma chain-breaking antioxidants and this may influence the susceptibility of the preterm baby to oxygen toxicity.

Effect of an exchange transfusion on plasma antioxidants in the newborn

The effect of an exchange transfusion on antioxidants in the plasma of newborns with rhesus hemolytic disease was studied. The antioxidant concentrations in donor blood were similar to normal adult values except for the lower vitamin C concentrations. Exchange transfusion decreased the newborns' iron and ferritin levels and increased their ceruloplasmin and transferrin (primary antioxidants) concentrations and latent iron-binding capacity. The changes in secondary antioxidant concentrations were variable; uric acid and thiols were stable, vitamin C and bilirubin fell, and vitamin E rose. The total peroxyl-radical trapping capacity of the secondary antioxidants did not change significantly. The fall in levels of thiobarbituric acid reactive substances, an index of lipid peroxidation, was related to the lower levels present in the donor blood. Exchange transfusion rapidly produced variable changes in the concentrations of prooxidant and antioxidant substances in plasma and may thus influence free radical metabolism in the newborn.

Limited protection against iron-induced lipid peroxidation by cord blood plasma

The ability of plasma from newborn babies (cord blood) and adults to inhibit iron-induced lipid peroxidation was compared. The caeruloplasmin and transferrin concentrations, and latent iron-binding capacity were lower in the babies (p less than 0.001). The plasma of many of the babies had no latent iron-binding capacity and contained non-protein-bound iron (measured by the bleomycin assay). The in vitro ability of plasma to inhibit iron-induced liposome peroxidation by either ferroxidase antioxidant activity (caeruloplasmin) or iron-binding antioxidant activity (transferrin) was measured. The antioxidant activity in both assays was decreased in the babies (p less than 0.001). The percentage inhibition of peroxidation in the iron-binding antioxidant assay correlated positively with the latent iron-binding capacity (p less than 0.001) and negatively with the presence of bleomycin-detectable iron (p less than 0.02) in the babies. This assay produced stimulation of peroxidation in 42% of the babies but none of the adults. The diminished capacity of cord blood plasma to prevent iron-induced lipid peroxidation may predispose the newborn baby to the toxic effects of oxygen.

Iron overload, free radical damage, and rhesus haemolytic disease

To test the hypothesis that iron overload induces free radical damage in rhesus haemolytic disease (RHD), cord blood plasma of babies with RHD was compared with that of controls matched for gestational age. Babies with RHD had higher ferritin levels, lower latent iron-binding capacity, increased concentrations of lipid-peroxidation products, and low vitamin C levels. Plasma of 3 RHD babies did not inhibit peroxidation stress. These findings, of iron overload and free radical damage, have implications for treatment of RHD.

The total free radical trapping ability of cord blood plasma in preterm and term babies

The interaction between various antioxidants may be important in protecting the newborn baby against oxygen toxicity. We studied the total radical trapping capacity of the antioxidants in plasma (TRAP) and compared the TRAP level in the preterm and term baby (cord blood) with that in adults. In addition, the concentrations of various known antioxidants were measured and the theoretical contribution of these antioxidants to the TRAP calculated. The measured and calculated TRAP were higher in the newborn babies than the adults. The uric acid concentration was similar in the three groups but the vitamin C concentration was higher and the vitamin E and sulfhydryl concentrations were lower in the newborn babies. In contrast to the adult group, the measured TRAP in the newborn babies did not correlate with the calculated TRAP. This may be due to differences in inhibition or recycling of antioxidants in the newborn and adult groups. Theoretical considerations showed that there may be a large unidentified group of antioxidants that contribute to measured TRAP in plasma. Bilirubin and beta-carotene were measured (higher and lower concentrations, respectively, in the newborn) in an attempt to identify these antioxidants. The efficient plasma radical trapping capacity in the cord blood may partly compensate for deficiencies in other components of the antioxidant defenses, e.g. cellular enzymes, at the time of birth.