Lack of antibody production against Hanganutziu-Deicher (H-D) antigens with N-glycolylneuraminic acid in patients with porcine exposure history

The significance of non-alphagalactosyl antigens remains unclear in pig-to-primate xenotransplantation. Hanganutziu-Deicher (H-D) antigens with terminal N-glycolylneuraminic acid (NeuGc) are widely expressed on endothelial cells of mammalian species, with the exception of humans. As baboons and monkeys also express H-D antigens, a pig-to-non-human primate experimental model cannot resolve the question of whether H-D antigens can elicit a potent humoral response in human recipients. The purpose of this study was to elucidate the clinical significance of H-D antigens by examining the sera from patients who have been previously exposed to porcine tissue. After the digestion of porcine aortic endothelial cells (PAEC) by neuraminidase, NeuGc and N-acetylneuraminic acid (NeuAc) were quantitated by HPLC. IgG and IgM antibody levels against H-D antigens were measured by NeuGc-GM3-coated ELISA plates in the sera of patients who had undergone ex vivo kidney perfusion 1 to 3 weeks and 2 years previously (n=2) or had been injected with fetal porcine islets 2 months previously (n= 10). HPLC determined that 9.7x 10(7) NeuAc and 6.3x 10(7) NeuGc residues per cell were released from PAEC by neuraminidase, while 25.7x 10(7) NeuAc and an undetectable level of NeuGc were released from human aortic endothelial cells (HAEC). No significant elevation of IgG or IgM antibody levels against NeuGc-GM3 was observed in sera from patients with a history of porcine exposure. Considering the active production of antibody against the foreign galactosyl antigens after pig-to-human xenotransplantation, some production of antibodies against the equally foreign H-D antigens would be expected, because large amounts of NeuGc terminated saccharides are present in the pig endothelial cell surface. However, no production of antibodies directed to H-D antigens could be found in patients exposed to porcine tissue. Further studies are warranted to explain why H-D antigens do not elicit a significant antibody production.     

Serum sialic acid in a random sample of the general population.

BACKGROUND: The serum sialic acid (SA) concentration has been reported to be a potentially useful but nonspecific disease marker. We wanted to study which factors influence SA concentration in a well-characterized healthy population. METHODS: SA was determined in 97 women and 96 men with a colorimetric Warren method. RESULTS: The mean +/- SD concentrations of SA were 634 +/- 109 (95% confidence interval, 612-656) and 630 +/- 106 (95% confidence interval, 608-651) mg/L for women and men, respectively. The serum SA showed a significant positive association with body mass index and with systolic and diastolic blood pressure among both women and men. SA also correlated significantly with the use of contraceptive pills and age among women and with smoking among men. CONCLUSIONS: Our study suggests that SA does not increase with age in men but appears to increase with female menopause. The strong positive association with blood pressure may explain why SA predicts cardiovascular mortality.     

Blood spillage during salvage

Recovery of blood components by salvage was evaluated in a randomized laboratory investigation using donor whole blood. Three methods of salvage were studied: conventional red cell salvage, red cell salvage with continuous processing, and salvage by haemofiltration using recirculation through a 30 000-Da filter. Less than 10% of the haemoglobin was wasted during processing by all three methods. About half of the leukocytes were recovered with no significant difference between the techniques. The recovery of platelets was 15, 4 and 41% during salvage with conventional red cell centrifugation, continuous centrifugation processing and haemofiltration, respectively. In contrast with the other methods, haemofiltration gave a major recovery of albumin.     

The complexity of the psychosocial situation in children and adolescents with heart disease

AIM: To describe the psychosocial situation of children/adolescents with heart disease and their families, an inventory method was worked out. METHODS: Ninety-seven children/adolescents with congenital heart disease (CHD) were graded into three categories with respect to complexity of CHD. Group I included 42 patients with malformations requiring standardized operations. Group II included 20 patients with more complicated malformations, and group III included 35 patients with very complex malformations. The patients were compared with controls without heart disease, matched for age and gender. The psychosocial impact of CHD was measured by the inventory. RESULTS: The most frequent problems in the patient group were healthcare and treatment-related needs (71/97) in the external sphere, family symptoms (68/97) in the interpersonal sphere, and somatic symptoms (19/97) in the personal sphere. Corresponding numbers in the controls were treatment-related needs (15/97), family (9/97) and somatic symptoms (25/97). Fifty per cent of the symptoms in the patient groups were mild, 30% moderate and 20% severe. The most severe symptoms were found in the interpersonal sphere, where family symptoms constituted the most severe variable. The frequency of severe problems in the personal sphere was 11% in the patients and 1% in the controls. This inventory method differentiates the grades of medical complexity both regarding number and severity of psychosocial symptoms. It indicates severe personal problems in the most complex group and shows that they have severe personal problems independent of family problems. CONCLUSION: This study elucidates the psychosocial complexity in children/adolescents with CHD, which has clinical implications in developing a psychosocial care programme.     

Expression of carbohydrate xenoantigens on porcine peripheral nerve

BACKGROUND: The use of thin easily revascularized cutaneous nerve autografts, which has been the gold standard, or the alternative use of nerve allografts or artificial grafts for nerve reconstructing have all their pros and cons. Nerve xenotransplantation may offer a potential alternative. In a potential pig to human nerve xenograft transplantation set-up several porcine antigen barriers have to be considered such as carbohydrate antigens system like the blood group A/O, the Galalpha1-3Gal (alphaGal) and the Hanganutziu-Deicher (HD) antigens. The swine leukocyte protein antigens system may also have to bee considered. The knowledge of the antigen expression on pig peripheral nerves is today limited. The present study describes the distribution of glycolipid based carbohydrate xenoantigens in ischiadicus nerve from blood group A and O pigs. METHODS: Glycolipid fractions were separated on thin layer chromatography plates and immunostained with human AB sera, biotinylated Griffonia simplicifolia isolectin B4, monoclonal antibodies reacting with the HD antigen and with blood group A antigens based on different core saccharide structures. In addition, the subcellular distribution of alphaGal and HD antigens were studied by light- and electron-microscopical immunohistochemistry. The total amount of neutral glycolipids was 15 mg/g tissue for both blood group A and O nerves with mono-glycosylceramides as the dominating component. RESULTS and CONCLUSIONS: The total amount of acidic glycolipids (gangliosides and sulpholipids) was 9 mg/g tissue for both the blood group O and A nerves with sulphatides as the dominating components. Analyses of the glycolipid fractions showed strong expression of both the alphaGal and the HD antigens in nerves from both blood group A and O pigs. In addition, small amounts of blood group A antigens were expressed in nerves from blood group A pigs. Staining of neutral glycolipids from blood group A pigs using monoclonal antibodies reacting with A antigen having different core structures suggested that the A epitope expressed on pig ischiadicus nerves is based on the type 1 core chain structure. Light and electron microscopical studies on the alphaGal and HD-antigen distribution revealed that the neural cells were alphaGal antigen negative. Endothelial cells of blood vessels, and lymphatic and perineural cells expressed alphaGal antigen. Both endothelial cells and myelinized axons revealed positively labelled for the HD antigen.     

Release of pig leukocytes during pig kidney perfusion and characterization of pig lymphocyte carbohydrate xenoantigens

The Galalpha1-3Gal (alphaGal) antigen is considered the main xenoantigen in the pig to human species combination but other porcine antigens have to be considered such as the swine lymphocyte antigen (SLA), the blood group A/O and the Hanganutziu-Deicher (H-D) antigens. The H-D antigens are N-glycolyl-neuraminic acid (NeuGc) terminated gangliosides that are widely distributed in mammalian species but absent in humans. Upon exposure to a vascularized pig organ, the human recipient can be immunized by direct interaction with the pig tissue or/and by transfer of tissue/cells from the organ into the recipient. In the present work, we describe the release of cells from porcine kidneys upon perfusion and the expression of glycolipid based alphaGal, blood group A/O and H-D antigens in pig lymphocytes. Pig kidneys were flushed with 20 ml of NaCl or Lidocain containing 5000 U heparin, and thereafter perfused with 3000-ml perfusion solution and the cells released were counted and examined microscopically. Neutral glycolipid and ganglioside fractions were extracted from purified pig lymphocytes. The extracted components were characterized by thin layer chromatography, degradation and mass spectrometry. The expression of alphaGal and H-D epitopes on cells released from pig kidneys and purified pig lymphocytes were studied by immune electron microscopy. A total amount of about 300 x 106 leukocytes, mainly lymphocytes were released in the perfusate from the kidneys, of which about 100 x 106 cells were eluated in the 600 to 2400 ml perfusate fraction. Immunelectron microscopical analysis with Griffonia simplicifolia isolectin B4 showed staining of pig leukocytes and other cells, morphologically similar to endothelial cells, released in the perfusate. The purified porcine lymphocytes contained 930 microg neutral glycolipid (4.2 microg/mg cell protein) of which 95% was glycolipids with one to four sugar residues. Immunostaining of the neutral glycolipid fractions revealed alphaGal terminated compounds migrating in the five and 10 to 12 sugar regions and blood group A compounds in the six and eight sugar regions. Two major gangliosides NeuGc-GM3 and NeuGc-GD3 were found in the pig lymphocytes. In a patient extracorporeally xenoperfused with a pig kidney, an increased staining of both alphaGal terminated structures as well as the H-D reactive gangliosides were found in the post-perfusion serum samples. In summary, leukocytes, mainly lymphocytes are released from pig kidneys during perfusion which may contribute to immunization of human xenograft recipients.     

Fundamentals of multichannel CT

Multichannel CT has become a very valuable tool in diagnostic imaging. It provides a combination of fast and long coverage in conjunction with thin slices. The fast scanning allows for single-breathhold scanning, fewer motion artifacts, and better use of intravenous contrast media. The brains of the MCCT scanners are the sophisticated detector arrays packed with electronics to handle the flow of image information. The submillimeter detectors rows offer isotropic properties to the image voxels, thereby creating viewing in any plane and better three-dimensional renderings.