ABO-incompatible heart transplantation in infants

BACKGROUND

Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens.

METHODS

We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors.

RESULTS

The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donor's blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent.

CONCLUSIONS

ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Preliminary Single-Center Canadian Experience of Human Normothermic Ex Vivo Liver Perfusion: Results of a Clinical Trial

After extensive experimentation, outcomes of a first clinical normothermic machine perfusion (NMP) liver trial in the United Kingdom demonstrated feasibility and clear safety, with improved liver function compared with standard static cold storage (SCS). We present a preliminary single-center North American experience using identical NMP technology. Ten donor liver grafts were procured, four (40%) from donation after circulatory death (DCD), of which nine were transplanted. One liver did not proceed because of a technical failure with portal cannulation and was discarded. Transplanted NMP grafts were matched 1:3 with transplanted SCS livers. Median NMP was 11.5 h (range 3.3-22.5 h) with one DCD liver perfused for 22.5 h. All transplanted livers functioned, and serum transaminases, bilirubin, international normalized ratio, and lactate levels corrected in NMP recipients similarly to controls. Graft survival at 30 days (primary outcome) was not statistically different between groups on an intent-to-treat basis (p = 0.25). Intensive care and hospital stays were significantly more prolonged in the NMP group. This preliminary experience demonstrates feasibility as well as potential technical risks of NMP in a North American setting and highlights a need for larger, randomized studies.

Controlled drinking by alcoholics? New findings and a reevaluation of a major affirmative study

Controlled drinking has recently become a controversial alternative to abstinence as an appropriate treatment goal for alcoholics. In this study we reexamine the evidence underlying a widely cited report by Sobell and Sobell of successful controlled drinking by a substantial proportion of gamma (physically dependent) alcoholic subjects in a behavior therapy experiment. A review of the evidence, including official records and new interviews, reveals that most subjects trained to do controlled drinking failed from the outset to drink safely. The majority were rehospitalized for alcoholism treatment within a year after their discharge from the research project. A 10-year follow-up (extended through 1981) of the original 20 experimental subjects shows that only one, who apparently had not experienced physical withdrawal symptoms, maintained a pattern of controlled drinking; eight continued to drink excessively--regularly or intermittently--despite repeated damaging consequences; six abandoned their efforts to engage in controlled drinking and became abstinent; four died from alcohol-related causes; and one, certified about a year after discharge from the research project as gravely disabled because of drinking, was missing.

Alcoholism

After heart disease and cancer, alcoholism is America's third largest health problem; it affects 10 million people, costs $ 60 billion, and is implicated in 200 000 deaths annually. Alcohol is involved in 50% of deaths by motor vehicle and fire, 67% of murders, and 33% of suicides. It contributes to morbidity in certain malignancies and to many diseases of the endocrine, cardiovascular, hematopoietic, gastrointestinal, and nervous systems. The fetal alcohol syndrome occurs in a third of the infants born to women who drink more than 150 g of ethanol daily during pregnancy; another third of the infants become mentally retarded. The prevalence of alcoholism is lower in elderly than in middle-aged persons, but detection is difficult and vulnerability to harm is great in the elderly, due to both pharmacokinetic factors and increased tissue sensitivity. Alcohol and aging are additive in their harmful effects. Although modern medical treatment is helpful, alcoholics are frequently misdiagnosed and mismanaged by health professionals. Total abstinence from alcohol should be a primary goal of treatment.

Defining critical windows in the development of the human immune system

Identifying critical windows in immune system development is crucial for determination of either safety or vulnerability to exposure to specific agents during rapidly changing phases of ontogeny. These phases in the human range from postconception early gestation through adolescence. A detailed understanding of these windows will facilitate avoidance of environmental toxins as well as allow improved planning for unavoidable exposures. Critical windows of immune development will be influenced by concomitant development, maturation and growth of other organ systems, thus the influence of potentially toxic exposures must be determined within a co-ordinated multisystem and multidisciplinary approach.

Equivalent outcomes for pediatric heart transplantation recipients: ABO-blood group incompatible versus ABO-compatible

ABO-blood group incompatible infant heart transplantation has had excellent short-term outcomes. Uncertainties about long-term outcomes have been a barrier to the adoption of this strategy worldwide. We report a nonrandomized comparison of clinical outcomes over 10 years of the largest cohort of ABO-incompatible recipients. ABO-incompatible (n = 35) and ABO-compatible (n = 45) infant heart transplantation recipients (< or =14 months old, 1996-2006) showed no important differences in pretransplantation characteristics. There was no difference in incidence of and time to moderate acute cellular rejection. Despite either the presence (seven patients) or development (eight patients) of donor-specific antibodies against blood group antigens, in only two ABO-incompatible patients were these antibodies implicated in antibody-mediated rejection (which occurred early posttransplantation, was easily managed and did not recur in follow-up). Occurrence of graft vasculopathy (11%), malignancy (11%) and freedom from severe renal dysfunction were identical in both groups. Survival was identical (74% at 7 years posttransplantation). ABO-blood group incompatible heart transplantation has excellent outcomes that are indistinguishable from those of the ABO-compatible population and there is no clinical justification for withholding this lifesaving strategy from all infants listed for heart transplantation. Further studies into observed differing responses in the development of donor-specific isohemagglutinins and the implications for graft accommodation are warranted.

Serious adverse drug reactions to pyrimethamine-sulphadoxine, pyrimethamine-dapsone and to amodiaquine in Britain

All reports of adverse reactions with pyrimethamine-sulphadoxine (Fansidar), pyrimethamine-dapsone (Maloprim), and amodiaquine spontaneously reported through the UK national post-marketing system were reviewed. Retrospective reporting rates of serious reactions associated with these drugs were analysed using prescription data from the Department of Health, derived from the Prescription Pricing Authority, and relevant pharmaceutical companies. Whilst interpretation of these data requires caution, they allowed comparison with reporting rates from other studies. The reported rate for all serious reactions to pyrimethamine-sulphadoxine was 1:2100 prescriptions, and for cutaneous reactions was 1:4900 prescriptions, with a fatality rate of 1:11,100. The reported rate for serious reactions to pyrimethamine-dapsone was 1:9100 prescriptions, and for blood dyscrasias was 1:20,000 prescriptions, with a fatality rate of 1:75,000. The reported rate of blood dyscrasias associated with amodiaquine was 1:2100 users with a fatality rate of 1:31,000. Serious hepatic disorders occurred in 1:11 1000 pyrimethamine-sulphadoxine prescriptions, 1:75,200 pyrimethamine-dapsone prescriptions, and in 1:15,650 amodiaquine users. 35% of cases received these drugs needlessly as they were not exposed to drug resistant strains of Plasmodium falciparum. Since few serious reactions have been reported to chloroquine plus proguanil, these data support guidelines which restrict the use of reviewed drugs for those at greatest risk of infection. Dosage data indicated that fatalities had taken higher doses and continued prophylaxis after onset of symptoms. Two thirds of serious reactions to the compound antimalarials were reported in females.

Discarded Human Thymus Is a Novel Source of Stable and Long-Lived Therapeutic Regulatory T Cells

Regulatory T cell (Treg)-based therapy is a promising approach to treat many immune-mediated disorders such as autoimmune diseases, organ transplant rejection, and graft-versus-host disease (GVHD). Challenges to successful clinical implementation of adoptive Treg therapy include difficulties isolating homogeneous cell populations and developing expansion protocols that result in adequate numbers of cells that remain stable, even under inflammatory conditions. We investigated the potential of discarded human thymuses, routinely removed during pediatric cardiac surgery, to be used as a novel source of therapeutic Tregs. Here, we show that large numbers of FOXP3(+) Tregs can be isolated and expanded from a single thymus. Expanded thymic Tregs had stable FOXP3 expression and long telomeres, and suppressed proliferation and cytokine production of activated allogeneic T cells in vitro. Moreover, expanded thymic Tregs delayed development of xenogeneic GVHD in vivo more effectively than expanded Tregs isolated based on CD25 expression from peripheral blood. Importantly, in contrast to expanded blood Tregs, expanded thymic Tregs remained stable under inflammatory conditions. Our results demonstrate that discarded pediatric thymuses are an excellent source of therapeutic Tregs, having the potential to overcome limitations currently hindering the use of Tregs derived from peripheral or cord blood.

The assessment of transplantation tolerance induced by anti-CD4 monoclonal antibody in the murine model

Transplantation tolerance can be induced in the adult mouse by the selective manipulation of the CD4+ T cell subset. C3H/He recipients with prolonged survival (> 120 days) of C57BL/10 cardiac allografts induced by treatment, at the time of transplantation, with the anti-CD4 mAb, YTS 191.1, were skin grafted simultaneously with donor-specific and third-party (BALB/c) skin. The development of donor-specific tolerance was proved by the specific prolongation of C57BL/10 skin graft survival, while third-party grafts were rejected. Further investigation of recipients with long-term surviving primary heart allografts showed that donor-specific tolerance was associated with organ-specific differences. Secondary cardiac allografts were universally accepted, even at 42 days after the primary heart transplant, while prolonged survival of donor-specific skin grafts was not obtained until more than 120 days after primary cardiac transplantation. Analysis of leukocyte reactivity in the mixed leukocyte culture (MLC) showed no correlation between the proliferative response of recipient T cells in vitro to either donor or third-party alloantigen and the survival of either heart of skin allografts. These results illustrate the significant challenge presented when attempting to define and assess accurately the state of transplantation tolerance.

Quality of life and function following cardiac transplantation in adolescents

Quality of life and functional status are important outcome measures following heart transplantation. The present study evaluated the quality of life and function of 10 adolescent heart transplant recipients at the Hospital for Sick Children. Subjects were surveyed using a visual analog quality of life scale, the Children's Depression Inventory, The Pediatric Quality of Life Scale 4.0, and the Functional Status IIR. Results demonstrated excellent perceived quality of life and psychologic well-being, comparable to healthy norms. Subscale results for physical, social, and emotional function provide evidence for positive responses to transplantation. As well, results on factors such as self-esteem, school, interpersonal function, and mood demonstrate gender differences that may influence outcomes. Studies are currently underway to further delineate these important quality of life, function, and psychosocial issues to ensure optimal outcomes are achieved in our patients.

ABH-Glycan Microarray Characterizes ABO Subtype Antibodies: Fine Specificity of Immune Tolerance After ABO-Incompatible Transplantation

Organ transplantation from ABO blood group-incompatible (ABOi) donors requires accurate detection, effective removal and subsequent surveillance of antidonor antibodies. Because ABH antigen subtypes are expressed differently in various cells and organs, measurement of antibodies specific for the antigen subtypes in the graft is essential. Erythrocyte agglutination, the century-old assay used clinically, does not discriminate subtype-specific ABO antibodies and provides limited information on antibody isotypes. We designed and created an ABO-glycan microarray and demonstrated the precise assessment of both the presence and, importantly, the absence of donor-specific antibodies in an international study of pediatric heart transplant patients. Specific IgM, IgG, and IgA isotype antibodies to nonself ABH subtypes were detected in control participants and recipients of ABO-compatible transplants. Conversely, in children who received ABOi transplants, antibodies specific for A subtype II and/or B subtype II antigens-the only ABH antigen subtypes expressed in heart tissue-were absent, demonstrating the fine specificity of B cell tolerance to donor/graft blood group antigens. In contrast to the hemagglutination assay, the ABO-glycan microarray allows detailed characterization of donor-specific antibodies necessary for effective transplant management, representing a major step forward in precise ABO antibody detection.

Effect of humic substances on Cu(II) solubility in kaolin-sand soil

The type and amount of organic matter present in industrially contaminated soils will influence the risk they pose. Previous studies have shown the importance of humic and fulvic acids (FAs) (important components of soil organic matter) in increasing the solubility of toxic metals but were not carried out using toxic metal levels and the pH range typical of industrially contaminated soils. This study investigated the influence of three humic substances (HSs: humates, fulvates and humins) on the solubility of copper(II) ions in kaolinitic soil spiked with Cu at levels representative of industrially contaminated soil. Humates, fulvates and humin were extracted from Irish moss peat, and controlled pH batch leaching tests were conducted on an artificial kaolin-sand soil that was spiked with each. Further leaching tests were conducted on soil spiked with each HS and copper nitrate. Dissolved organic contents were determined by titration and total and free aqueous copper concentrations in the leachate were measured using AAS and ion selective electrode (ISE) potentiometry respectively (dissolved complexed copper levels were determined by difference). It was found that humates and fulvates are partially sorbed by the soil, probably by chemisorption on positively charged gibbsite (Al-hydroxide) sites in the kaolinite. The addition of 340 mg/kg Cu(II) ions did not significantly affect the amount of humate or fulvate sorbed. Dissolved humates and fulvates form soluble complexes with copper over the pH range 3-11. However, in the presence of kaolinite, soluble copper humates and fulvates are unable to compete with the kaolinite for Cu ions at pH 6-7. Above pH 8, humate and fulvate complexes are the only forms of dissolved Cu. Humin is largely insoluble and has little effect on Cu mobility between pH 2 and 12. The implication of this study is that measurement of total soil organic content and water leaching tests should be a standard part of contaminated site investigation.

Chemical Basis for Qualitative and Quantitative Differences Between ABO Blood Groups and Subgroups: Implications for Organ Transplantation

Blood group ABH(O) carbohydrate antigens are carried by precursor structures denoted type I-IV chains, creating unique antigen epitopes that may differ in expression between circulating erythrocytes and vascular endothelial cells. Characterization of such differences is invaluable in many clinical settings including transplantation. Monoclonal antibodies were generated and epitope specificities were characterized against chemically synthesized type I-IV ABH and related glycans. Antigen expression was detected on endomyocardial biopsies (n = 50) and spleen (n = 11) by immunohistochemical staining and on erythrocytes by flow cytometry. On vascular endothelial cells of heart and spleen, only type II-based ABH antigens were expressed; type III/IV structures were not detected. Type II-based ABH were expressed on erythrocytes of all blood groups. Group A1 and A2 erythrocytes additionally expressed type III/IV precursors, whereas group B and O erythrocytes did not. Intensity of A/B antigen expression differed among group A1 , A2 , A1 B, A2 B and B erythrocytes. On group A2 erythrocytes, type III H structures were largely un-glycosylated with the terminal "A" sugar α-GalNAc. Together, these studies define qualitative and quantitative differences in ABH antigen expression between erythrocytes and vascular tissues. These expression profiles have important implications that must be considered in clinical settings of ABO-incompatible transplantation when interpreting anti-ABO antibodies measured by hemagglutination assays with reagent erythrocytes.

Fetal liver haematopoietic cells and tolerance to organ allografts

Fetal liver haematopoietic cells were used to induce neonatal tolerance to cardiac allografts. Newborn mice were injected with fetal or newborn haematopoietic liver cells in two fully allogeneic strain combinations. There was no clinical evidence of graft-versus-host disease. Long-term survival of subsequent cardiac allografts occurred in both strains without immunosuppressants. Unresponsiveness was found not be be donor-specific with prolongation of third-party allografts as well as donor-type grafts. These findings have important implications for inducing tolerance in paediatric organ transplantation.

Outcomes for children with cardiomyopathy awaiting transplantation

OBJECTIVE

To determine factors associated with outcomes after listing for transplantation in children with cardiomyopathies.

BACKGROUND

Childhood cardiomyopathies form a heterogeneous group of diseases, and in many, the prognosis is poor, irrespective of the etiology. When profound heart failure develops, cardiac transplantation can be the only viable option for survival.

METHODS

We included all children with cardiomyopathy listed for transplantation between 12/89 and 4/98 in this historical cohort study.

RESULTS

We listed 31 patients, 15 male and 16 female, 27 with dilated and 4 with restrictive cardiomyopathy, for transplantation. The median age at listing was 5.7 years, with a range from fetal life to 17.8 years. Transplantation was achieved in 23 (74%), with a median interval from listing of 54 days, and a range from zero to 11.4 years. Of the patients, 14 were transplanted within 30 days of listing. Five patients (16%) died before transplantation. Within the Canadian algorithm, one of these was in the third state, and four in the fourth state. One patient was removed from the list after 12 days, having recovered from myocarditis, and two remain waiting transplantation after intervals of 121 and 476 days, respectively. Patients who died were more likely to be female (5/5 vs. 11/26; p=0.04) and to have been in the third or fourth states at listing (5/5 vs. 15/26; p=0.04). The use of mechanical ventricular assistance, in 10 patients, was not a predictor of an adverse outcome. While not statistically significant, survival to transplantation was associated with treatment using inhibitors of angiotensin converting enzyme, less mitral regurgitation, a higher mean ejection fraction and cardiac index, and lower right ventricular systolic pressure.

CONCLUSIONS

Children with cardiomyopathy awaiting transplantation have a mortality of 16% related to their clinical state at the time of listing.

Dental management of the patient with major depression

Major depression is a psychiatric disorder in which mood, thought content, and behavioral patterns are impaired for long periods of time. It is a common disorder, with an increasing prevalence among young adults. It may be associated with a disinterest in performing appropriate preventive oral hygiene techniques, a cariogenic diet, diminished salivary flow, rampant dental decay, advanced periodontal disease, and oral dysesthesias. Many medications used to treat the disease magnify the xerostomia and increase the incidence of dental disease. Appropriate dental management necessitates a vigorous preventive dental education program, the use of saliva substitutes and anticaries agents containing fluoride, and special precautions when prescribing or administering analgesics and local anesthetics.

Groundwater flow velocities in a fractured carbonate aquifer-type: Implications for contaminant transport

Contaminants that are highly soluble in groundwater are rapidly transported via fractures in mechanically resistant sedimentary rock aquifers. Hence, a rigorous methodology is needed to estimate groundwater flow velocities in such fractured aquifers. Here, we propose an approach using borehole hydraulic testing to compute flow velocities in an un-faulted area of a fractured carbonate aquifer by applying the cubic law to a parallel plate model. The Cadeby Formation (Yorkshire, NE England) - a Permian dolostone aquifer present beneath the University of Leeds Farm - is the fractured aquifer selected for this hydraulic experiment. The bedding plane fractures of this dolostone aquifer, which are sub-horizontal, sub-parallel and laterally persistent, largely dominate the flow at shallow (<~40 mBGL) depths. These flowing bedding plane discontinuities are separated by a rock matrix which is relatively impermeable (K_well-test/K_core-plug~10⁴) as is common in fractured carbonate aquifers. In the workflow reported here, the number of flowing fractures - mainly bedding plane fractures - intersecting three open monitoring wells are found from temperature/fluid conductivity and acoustic/optical televiewer logging. Following well installation, average fracture hydraulic apertures for screened intervals are found from analysis of slug tests. For the case study aquifer, this workflow predicts hydraulic apertures ranging from 0.10 up to 0.54 mm. However, groundwater flow velocities range within two order of magnitude from 13 up to 242 m/day. Notably, fracture apertures and flow velocities rapidly reduce with increasing depth below the water table; the upper ~10 m shows relatively high values of hydraulic conductivity (0.30-2.85 m/day) and corresponding flow velocity (33-242 m/day). Permeability development around the water table in carbonate aquifer-types is common, and arises where high pCO₂ recharge water from the soil zone causes calcite/dolomite dissolution. Hence, agricultural contaminants entering the aquifer with recharge water are laterally transported rapidly within this upper part. Computation of groundwater flow velocities allows determination of the Reynolds number. Values of up ~1, indicating the lower limit of the transition from laminar to turbulent flow, are found at the studied site, which is situated away from major fault traces. Hence, turbulent flow is likely to arise in proximity to tectonic structures, such as normal faults, which localize flow and enhance karstification. The occurrence of turbulent flow in correspondence of such tectonic structures should be represented in regional groundwater flow simulations.