Procalcitonin for differential diagnosis of graft rejection and infection in patients with heart and/or lung grafts

OBJECTIVES

Investigation of the reliability of Procalcitonin (PCT) for differential diagnosis of acute rejections and non-viral infections in heart and lung transplanted patients.

DESIGN

Retrospective study.

SETTING

Transplant intensive care unit (ICU) at a university hospital.

PATIENTS

57 heart, 18 lung and 3 heart-lung transplant patients.

MEASUREMENTS

PCT was measured in plasma samples of heart and lung transplanted patients using a commercial immuno-luminescence assay and was compared with values of C-reactive protein (CRP) and leukocytes (WBC).

RESULTS

PCT was elevated in patients suffering from bacterial and fungal infections. The magnitude of values was clearly associated with the severity of the infection. Rejections and viral infections did not interfere with the PCT release.

CONCLUSION

PCT is a reliable predictor with discriminating power for non-viral systemic infections in patients after heart and/or lung transplantation. PCT allows an early differential diagnosis between rejection (AR) and bacterial/fungal infection (IF) and thus a rapid and focused therapeutic intervention. It avoids unnecessary antibiotic treatment which could be toxic for the graft itself in patients with rejection only. PCT provides vital information early to clinicians and allows them to improve the management of bacterial/fungal infections in immunocompromized transplant patients. PCT thus facilitates and improves the outcome of survival rate and the quality of life in the postoperative period of patients with heart and/or lung grafts.

Transgenic animals in experimental xenotransplantation models: orthotopic heart transplantation in the pig-to-baboon model

Pig organs are at risk for hyperacute and acute vascular rejection mediated by anti-pig antibodies, mainly binding to the Galalpha(1,3)Gal epitope. Acute cellular rejection is characterized by progressive infiltration of mononuclear cells. There is an ongoing search for immunosuppressive regimens that provide adequate protection against all patterns of xenograft rejection, but have no severe impact on the condition of xenograft recipients. Herein orthotopic heart transplantations were performed from hDAF or hCD46 piglets to nonsplenectomized baboons. Basic immunosuppression consisted of tacrolimus, sirolimus, GAS914, steroids, and ATG. Group 1 received basic immunosuppression. Group 2 was additionally treated with rituximab and group 3 with half-dose cyclophosphamide. Group 4 received cyclophosphamide and an anti-HLA-DR antibody. Three baboons received GAS914 and TPC. Monitoring included the regular assessment of anti-porcine antibodies, blood counts, therapeutic drug monitoring, and graft histology. Two grafts failed due to technical mistakes. In group 1, baboons died after 1 and 9 days. In group 2, maximum survival was 30 hours. In group 3, baboons lived 20 hours, 25 days, and 14 days. Group 4 survival times were 9.5 hours, 5.5 hours, 4 days, 34 hours, and 3 days. An increase of non-Galalpha(1,3)Gal antibodies was observed. Depositions of immunoglobulins and complement revealed a humoral rejection process. No cellular infiltration could be observed. In conclusion, suppressing cellular rejection with half-dose cyclophosphamide together with tacrolimus and sirolimus produced longer graft survival with a good general condition. Prevention of acute xenograft rejection further needs inhibition of non-Galalpha(1,3)Gal cytotoxicity by sufficient depression of B-cell activation.

Fluorescent microspheres reveal different regional blood flow in hyperacutely rejected nontransgenic and hDAF pig hearts

Classic features of hyperacute rejection show differential severity in the inner compared to the outer myocardium. In the present study, regional blood flow (RBF) measured by fluorescent microspheres served as a marker of the extent of hyperacute rejection. Using a working heart model, hearts of nontransgenic and hDAF transgenic pigs were perfused with human blood. Additionally, hDAF transgenic pig hearts were perfused with human blood containing GAS914 or the GPIIb/IIIa inhibitor tirofiban. Injections of fluorescent microspheres into the donor heart were performed in situ and during perfusion. Reference arterial blood samples were collected from the inferior aorta and the afterload line. Perfusion was terminated before hyperacutely rejected hearts failed to pump against the afterload column. RBF was determined in tissue samples of standardized areas of the left atrium and ventricle. Each specimen was divided into subepicardial and subendocardial tissue samples. Fluorescence intensity was measured using an automated luminescence spectrometer. At the end of perfusion with human blood, hyperacutely rejected nontransgenic pig hearts showed a higher RBF in the subendocardium. In hDAF-transgenic pig hearts perfused with unmodified human blood the subendocardial/subepicardial blood flow ratio changed in favor of the subepicardium. This ratio was not further improved by GAS914. In contrast, tirofiban was able to assimilate subepicardial and subendocardial blood flow. In conclusion, RBF of hyperacutely rejected pig hearts was inhomogeneous. Inhibition of complement activation improved the reduced subepicardial RBF, but depletion of antibodies had no positive effect. The ability of tirofiban to further increase subepicardial RBF affirms thrombosis of subepicardial veins as the defining characteristic of hyperacute rejection.

Biochemische Serumparameter bei in Gefangenschaft gehaltenen Gazellen

Ziel der Untersuchung war, Serumparametervon klinisch unauffälligen Gazellen der Al Wabra Wildlife Preservation (AWWP), Qatar, mit Referenzbereichen von Haus- und anderen Wildwiederkäuern zu vergleichen, um einerseits Rückschlüsse auf den Ernährungszustand der Tiere zu ermöglichen und andererseits Referenzbereiche für die untersuchten Arten zu etablieren. Material und Methoden: Von 250 klinisch gesunden Tieren der Arten Sömmeringgazelle (Gazella soemmerringii), Spekegazelle (Gazella spekei), Dor-kasgazelle (Gazella dorcas), Saudigazelle (Gazella saudiya), Echtgazelle (Gazella gazella), Arabische Kropfgazelle (Gazella subgutturosa marica) und Chinkaragazelle (Gazella benetti) wurden biochemische Serumparameter und Mineralgehalte gemessen. Ergebnisse: Hinsichtlich des Ernährungszustandes war die Versorgung mit Spurenelementen (Selen, Kupfer, Zink, Eisen) in der AWWP gemäß den gemessenen Serumgehalten gewährleistet. Die Gehalte an Phosphor, Gesamtprotein und Albumin deuteten jedoch auf eine suboptimale Fütterung hin, die vermutlich mit der minderen Qualität des in der Region verfügbaren Raufutters zusammenhängt. Die Gehalte an Natrium, Kalium, Kalzium, Magnesium, Chlor, Triglyzeriden, Cholesterin, Kreatinin sowie die ALT- und γ-GT-Aktivität lagen-wie bei anderen Wildwiederkäuern auch - im Referenzbereich für Hauswiederkäuer, der daherfür die Beurteilung dieser Parameter bei Wiederkäuern generelle Gültigkeit besitzen dürfte. Die Gehalte an Glukose, Harnstoff-Stickstoff, Kreatinkinase sowie die AP-Aktivität hingegen scheinen bei Wildwiederkäuern generell erhöht zu sein. Während andere Wildwiederkäuer für AST mit Hauswiederkäuern vergleichbare Werte aufweisen, ist die Aktivität dieses Enzyms bei Gazellen in dieser und in anderen Studien durchweg erhöht. Schlussfolgerung und klinische Relevanz: Die in der Untersuchung festgestellten Besonderheiten müssen bei der Beurteilung von Blutanalysen beachtet werden.

Mean xenograft survival of 14.6 days in a small group of hDAF-transgenic pig hearts transplanted orthotopically into baboons

INTRODUCTION

In a discordant orthotopic xenotransplantation model (pig-to-baboon) donor pigs expressing human decay accelerating factor (hDAF) as a regulator of complement activity were used to prevent hyperacute xenograft rejection (HXR). We investigated a modified immunosuppressive therapy consisting of ERL080 (Novartis Pharma AG, Base, Switzerland), cyclosporin A (Neoral), steroids, and a cyclophosphamide (CyP) induction protocol with several reduced doses to prevent acute vascular rejection (AVR).

METHODS

Donor hearts were harvested from hDAF-transgenic pigs (18.8 +/- 2.6 kg, Imutran Ltd., a Novartis Pharma AG Company). Four adult baboons (25.6 +/- 2.7 kg) with high titers of xenoreactive antibodies (XAb) served as recipients. Serological and hemodynamic parameters were measured. Finally, myocardial tissue was sampled for histological and immunohistochemical examinations.

RESULTS

In the first baboon, an acute graft failure occurred after 1 hour due to preservation injury. The second succumbed after 11.1 day due to an acute renal failure. The third died after 13.1 days of an ileus. The fourth baboon had continuously excellent cardiac function (mean echocardiographic ejection fraction, 69.2%), but succumbed on day 20 due to anemia. Corrected mean xenograft survival (excluding the first baboon because of a technical failure) was 14.6 +/- 2.6 days. XAb decreased after day 3 to constantly low levels (<1:64 titer) after CyP induction. White blood cell count decreased from 10.3 +/- 0.8 to 0.9 +/- 0.3 G/L after day 3. Macroscopically and histologically no typical signs of HXR or severe AVR could be detected.

CONCLUSIONS

These results confirm that hDAF transgen blocks HXR in this life-supporting model. AVR was prevented by using a modified quadruple immunosuppressive drug combination (Neoral, ERL080, steroids, and several small single doses of CyP). An optimum "fine-tuning" of immunosuppression is required to achieve the best risk-benefit ratio.

Combination of hDAF-transgenic pig hearts and immunoadsorption in heterotopic xenotransplantation of immunosuppressed baboons

INTRODUCTION

Hyperacute xenograft rejection (HXR) and acute vascular rejection (AVR) after xenotransplantation are triggered by xenoreactive antibodies (XAb) and an activated complement cascade. In a heterotopic (abdominal) xenotransplantation model we combined immunoadsorption (IA, Ig-Therasorb column) and a quadruple immunosuppressive drug therapy in recipient baboons with donor pig hearts transgenic for human decay accelerating factor (hDAF).

METHODS

According to XAb titers between 6 and 14 cycles of IA were performed preoperatively in 4 recipient baboons (18.6 +/- 2.5 kg). Hearts of hDAF-transgenic donor pigs (6.1 +/- 1.1 kg, Imutran Ltd., a Novartis Pharma AG Company, Basel, Switzerland) were heterotopically transplanted using the abdominal technique in baboons. Immunosuppression consisted of cyclophosphamide (CyP) induction therapy, ERL080 (Novartis Pharma AG), cyclosporin A (CyA, Neoral), and steroids. Blood levels of mycophenolate, CyA, immunoglobulins (Ig), anti-pig-antibodies, complement factors, and cardiac enzymes were determined. Abdominal electrocardiography (ECG), echocardiography, and palpation were used for monitoring of the pig hearts. Myocardial tissue specimens were examined using immunohistochemistry, light microscope (LM), and electron microscope (EM).

RESULTS

Ten cycles of IA alone removed 78% of XAb and accordingly IgM, IgG, IgA, complement C3, and C4. None of the xenografts was hyperacutely rejected, but xenograft failure occurred after 5.0 +/- 1.3 days (range, 2.4-8.0 days) because of an AVR associated with a rapid XAb increase within 24 hours. White blood cell count (10.3 +/- 2.2 G/L) showed a maximum of 13.1 +/- 2.1 (day 1) and constant levels (1.4 +/- 0.3-2.1 +/- 1.3 G/L) between day 3 and 6. Histology (LM/EM) showed massive hemorrhage, necrosis, and vascular thrombi as signs of AVR.

CONCLUSION

Although HXR was prevented by using IA and hDAF-transgenic donor hearts, AVR was not avoided due to insufficient immunosuppressive regimen used and a missed postoperative IA treatment as a result of an inefficient control of XAb production.

Influence of Polyclonal ATGs on Expression of Adhesion Molecules: An Experimental Study

BACKGROUND

The aim of our study was to assess the influence of polyclonal antithymocyte globulins (ATGs) on the expression of adhesion molecules on lymphocytes, neutrophils, and thrombocytes by means of flow cytometry. ATGs are employed in various regimens for solid organ transplantation. Immunosuppression with ATGs may influence the expression of adhesion molecules on thrombocytes, lymphocytes, and neutrophils due to nonspecific antibodies directed against myeloid and nonmyeloid cells.

MATERIAL AND METHODS

Depletion, activation, and expression of adhesion molecules on thrombocytes (CD41, CD42, CD62p and CD107a), neutrophils, and lymphocytes (CD11, CD18, CD62L) were studied in vitro in whole blood of healthy volunteers by means of flow cytometry after incubation with different dosages of three ATGs.

RESULTS

Our data showed no ATG-mediated cytotoxic activity against platelets. ATGs were able, however, to induce activation of platelets through increased expression of P-selectin and hLAMP-1. ATGs also influenced the expression of adhesion molecules on lymphocytes and neutrophils by reducing the expression of CD62L. Furthermore, the effects of ATG on CD11/CD18 were dependent on the dosage and type of ATG.

CONCLUSION

Polyclonal ATGs induced expression of adhesion molecules and activation of unstimulated thrombocytes as well as reduced the expression of adhesion molecules on lymphocytes and neutrophils. Increased adhesion of thrombocytes may be responsible for the undesirable side effects observed in clinical practice such as thrombocytopenia. However, reduction in the expression of adhesion molecules on lymphocytes and neutrophils may decrease the effects of ischemia/reperfusion injury.

Combining the hDAF transgene with the GP IIb/IIIa inhibitor tirofiban improves heart performance and reduces myocardial damage following hyperacute rejection in an ex vivo perfusion model

Xenograft rejection is associated with vascular injury resulting at least in part from platelet activation, and rejected xenografts invariably demonstrate intravascular thrombosis. Assuming that complement activation is a major determinant of humoral immune reactions bringing about platelet-endothelial cell interactions, we tested the effects of the specific platelet glycoprotein IIb/IIIa inhibitor tirofiban in combination with the human decay accelerating factor (hDAF) transgene on hyperacute rejection of pig hearts. Four groups were studied in a working heart-perfusion model. Pig hearts transgenic for hDAF and nontransgenic pig hearts were perfused with human blood containing tirofiban or with unmodified human blood. Cardiac output, stroke work index, and creatine phosphokinases were measured for the evaluation of the extent of myocardial damage. Consumption of complement components was determined. Endothelial deposition of fibrin and intravascular thrombosis were evaluated. Tirofiban improved cardiac output and stroke work index of nontransgenic pig hearts and was able to further increase hemodynamic function of hDAF transgenic pig hearts. Low levels of creatine phosphokinases also revealed a cardioprotective effect of tirofiban. However, a further extension of the survival of hDAF transgenic pig hearts could not be achieved, although tirofiban prolonged beating time of nontransgenic pig hearts. Tirofiban was able to reduce the consumption of complement components independently of hDAF. Intravascular evidence of fibrin and thrombosis tended to be particularly reduced by the combination of tirofiban and hDAF. Thus, the application of tirofiban together with hDAF improves the performance of pig hearts by reducing myocardial damage and intravascular thrombosis.

Impact of small variations of ischemia time after polyclonal antithymocyte globulins in a nonhuman primate model ofischemia–reperfusion injury

Ischemia-reperfusion injury leads to increased leukocyte adherence enhancing acute cellular rejection, causing microvascular dysfunction and tissue damage. The length of the ischemic time is important in clinical transplantation. Polyclonal antithymocyte globulins (pATGs) induce T-cell depletion and functional impairment of nondepleted lymphocytes. In this study cynomolgus monkeys were used to evaluate the impact of three different pATGs on the microcirculation, on leukocyte behavior and infiltration, as well as on tissue damage after two different periods of ischemia (60 and 150 minutes). pATGs were administered 30 minutes before ex vivo reperfusion. Using intravital fluorescence microscopy, the postreperfusion microcirculation was visualized in vivo. Morphologic analyses were performed on biopsies obtained after the experiments. Significant differences were observed between the two periods of ischemia in both the ATG-treated and control groups. Minimizing ischemia time, even in short intervals, improves the outcome of ischemia-reperfusion injury by reducing leukocyte adherence to the antigen-presenting endothelial cells, improving the microcirculation, and reducing tissue damage.

Hormonal Counterregulation during Severe Hypoglycaemia under Everyday Conditions in Patients with Type 1 and Insulin-Treated Type 2 Diabetes Mellitus

AIM

To determine the counterregulatory hormonal responses to severe hypoglycaemia (SH) in type 1 versus insulin-treated type 2 diabetic patients under everyday conditions.

METHODS

Counterregulatory hormones were determined in 28 consecutive type 1 and thirteen insulin-treated type 2 diabetic patients (age 54 +/- 18 vs. 75 +/- 13 yrs; diabetes duration 27 +/- 16 vs. 21 +/- 6 yrs) with SH requiring emergency treatment. Blood samples were taken prior to and after effective treatment of SH. SH was defined as an event with neuroglycopenic presentation requiring external intervention by administration of intravenous glucose or oral carbohydrates. 68 % (19/28) of type 1 diabetic patients but none of those with type 2 diabetes had reduced awareness of hypoglycaemia.

RESULTS

Plasma glucose levels were 30 +/- 14 prior to and 179 +/- 82 mg/dl after treatment of SH; the time between the two measurements was 54 +/- 26 minutes. With the exception of higher levels of human growth hormone in type 1 patients - which were attributed to younger age - the other counterregulatory responses to SH showed no significant differences in type 1 vs. type 2 diabetic patients. In both groups glucagon responses were virtually absent while moderate catecholamine responses could be demonstrated. Treatment with beta-blockers did not affect hormonal counterregulation in type 1 diabetic patients.

CONCLUSIONS

In patients approaching the insulin-deficient end of the spectrum of type 2 diabetes the hormonal responses to SH are comparable to those in patients with longstanding type 1 diabetes. Thus, in advanced type 2 diabetes the risk of developing SH may be similar to that in individuals with type 1 diabetes.

Xenotransplantation--will it bring the solution to organ shortage?

Xenotransplantation, the transplantation of organs, tissues and cells from animals, preferably pig-to-man, might be considered to become the transplantation of the future. Organs from domestic animals are available in unlimited numbers for xenogeneic transplantation and could swiftly solve the problem of organ shortages. Domestic animals of about the same size as human beings would be ideal organ sources. By selective breeding the anatomical and some physiological characteristics of these animals could be at least partly adapted to match the human body. However, the immunological mechanisms and the antigenicity of cells and their surface structures will remain obstinately unaltered. The only hope is that wide-reaching transgenic manipulation of animals, will soon achieve great changes in immunological and physiological circumstances.

Induction of immunosuppression with polyclonal antithymocyte globulins: an overview

The induction of immunological tolerance to solid organ allograft is currently a subject of major investigation due to the morbidity and mortality related to immunosuppressive therapy. Immunosuppression induction by recipient treatment may allow to tailoring the timing and dosage of standard therapy not only reducing adverse reactions but also improving the graft outcome. Depletion of recipient T cells with polyclonal antithymocyte globulins is one of the methods nowadays investigated both in experimental and clinical procedures, demonstrating a better outcome of organ engraftment. Our intention is to give an overview of the literature about the mechanisms of action of polyclonal ATGs, the status of induction treatment in clinical and experimental transplantation as well as of the possible pathophysiological relationships with acquired tolerance, delayed graft failure and ischemia-reperfusion injury.

Hormonal counterregulation and consecutive glimepiride serum concentrations during severe hypoglycaemia associated with glimepiride therapy

OBJECTIVE

To examine the release of counterregulatory hormones and consecutive glimepiride serum concentrations during severe hypoglycaemia (SH) associated with glimepiride therapy.

METHODS

In nine type-2 diabetic patients [age 81+/-9 (65-93) years; diabetes duration 9+/-4 (3-15) years; initial blood glucose 33+/-16 (10-54) mg/dl (1.8+/-0.9 mmol/l); HbA1c 7.2+/-1.1 (5.6-8.7)%; creatinine clearance 49+/-33 (15-107) ml/min] who experienced SH associated with glimepiride therapy with neuroglucopenic presentation, insulin, C-peptide, glucagon, epinephrine, norepinephrine, cortisol, adenocorticotrophic hormone (ACTH), human growth hormone (HGH) and pancreatic polypeptide (PP) were determined in blood samples taken at 4-h intervals prior to and during treatment with glucose i.v. Serum from the same samples was screened for sulphonylurea-type oral antidiabetics. Glimepiride concentrations were determined by a validated atmospheric pressure chemical ionization liquid chromatographic-mass spectrometry (APCI-LC-MS) assay.

RESULTS

Once treatment had begun, normoglycaemia was maintained; most glimepiride levels were below the limit of detection (LOD <0.01 mg/l) and further sulphonylureas could be excluded. The secretion of glucagon and epinephrine as counterregulatory hormonal responses was unaffected. In addition, protracted marked increases of cortisol and norepinephrine levels were demonstrated. Protracted stimulation of insulin and C-peptide occurred in a period of up to 24 h after SH. No significant protracted responses were observed for ACTH, HGH or PP.

CONCLUSION

In SH associated with glimepiride therapy, no correlation between glimepiride serum concentrations and the protracted stimulation of insulin and C-peptide was observed. The secretion of glucagon and epinephrine as counterregulatory hormonal responses was unaffected. Protracted increased release of cortisol might be a medium-term indicator of glimepiride-associated SH.

Direct assessment and distribution of regional portal blood flow in the pig by means of fluorescent microspheres

Measurement of regional organ blood flow by means of fluorescent microspheres (FM) is an accepted method. However, determination of regional portal blood flow (RPBF) cannot be performed by microspheres owing to the entrapment of the spheres in the upstream capillary bed of the splanchnic organs. We hypothesized that an adequate experimental setting would enable us to measure RPBF by means of FM and to analyze its distribution within the pig liver. A mixing chamber for the injection of FM was developed, and its capability to distribute FM homogeneously in the blood was evaluated in vitro. The chamber was implanted into the portal vein of six anesthetized pigs (23.5 +/- 2.9 kg body wt). Three consecutive, simultaneous injections of FM of two different colors into the chamber were performed. Reference portal blood samples were collected by means of a Harvard pump. At the end of the experiment, the liver was explanted and fixed in formalin before dissection. FM were isolated from the tissue samples by an automated process, and fluorescence intensity was determined. Comparison of 5,458 single RPBF values, determined by simultaneously injected FM, revealed good agreement (bias 2.5%, precision 12.7%) and high correlation (r = 0.97, r2 = 0,95, slope = 1.04, intercept = 0.05). Median RPBF was 1.07 +/- 0.78 ml x min(-1) x g(-1). Allocation of the blood flow values to the anatomic regions of the liver revealed a significantly higher RPBF (P = 0.01) in the liver tissue located close to the diaphragm compared with the rest of the organ and a significantly lower RPBF (P = 0.01) in the left liver lobe compared with the median and right lobes. The results show that the model presented makes it possible to measure RPBF by means of FM reliably and that RPBF is distributed heterogeneously in the porcine liver.

Characteristics and time course of severe glimepiride- versus glibenclamide-induced hypoglycaemia

OBJECTIVE

To compare the clinical characteristics and time course of severe hypoglycaemia (SH) on glimepiride and the reference drug glibenclamide.

METHODS

SH was defined as a symptomatic event requiring administration of i.v. glucose or of glucagon. Four hundred doctors working in acute care hospitals were randomly selected from the membership directory of the German Diabetes Association and sent a standardised questionnaire about sulphonylurea-induced SH that occurred between June 2001 and August 2002. Detailed data on history, medication, laboratory parameters, treatment and time course of the SH were analysed.

RESULTS

Altogether, 93 episodes of SH were registered, 37 on glimepiride and 56 on glibenclamide. The characteristics of the glimepiride- versus glibenclamide-induced SH were as follows: initial blood glucose 1.9+/-0.66 mmol/l versus 1.8+/-0.89 mmol/l, P=0.17; age 77+/-11.2 years versus 78+/-9.6 years, P=0.35; HbA1c 5.4+/-0.7% versus 5.2+/-0.9%, P=0.18; creatinine clearance 38+/-23 ml/min versus 54+/-32 ml/min, P=0.005; co-medication 6.2.+/-3 versus 3.6+/-3 preparations, P< 0.0001. Even very low doses of glimepiride (0.5 mg) and glibenclamide (0.88 mg) were associated with SH. Prolonged hypoglycaemia requiring more than 12 h i.v. glucose administration occurred in 8 of 37 of the glimepiride-treated subjects and 5 of 56 of those on glibenclamide. Prolonged hypoglycaemia necessitated infusion of 308+/-256 g (104-862 g) i.v. glucose over 43+/-16 h (24-64 h) in glimepiride-treated patients compared with 168+/-98 g (66-300 g) over 33+/-28 h (14-80 h) in glibenclamide-treated patients. Impaired renal function was present in 11 of 13 of all patients with prolonged hypoglycaemia and impaired liver function in 1 of 13.

CONCLUSION

In glimepiride- and glibenclamide-treated individuals with SH, no essential differences in the clinical characteristics or time course were shown; prolonged courses also occurred on glimepiride. Even in patients with only mild renal failure both preparations should be used with caution.

Xenotransplantation: the good, the bad, and the ugly or how far are we to clinical application?

On the way to successful clinical XTP many obstacles have to be overcome, and new difficulties might still arise. For clinical XTP all "players of the concert" have to harmonize. It is not enough if one molecule is recognized by its receptor. A chain is only as strong as its weakest link; this is also true for xenogeneic immunology, physiology, and pharmacology. The phylogeneic distance between man and pig comprises 180 million years. This tremendous distance has to be bridged by new and still unknown methods to outwit evolution.

Morphological assessment of reperfusion injury in a concordant xenogeneic primate model

Ischemia and consecutive reperfusion injury of the graft cannot be avoided in organ transplantation. One principal characteristic of this process is the temporary and permanent adherence of leukocytes to endothelial cells of the graft as well as damage of the associated tissue. Polyclonal antithymocyte globulins (ATGs) are used to prevent acute rejection after transplantation and to overcome graft vs. host disease. ATGs induce apoptosis and complement-mediated cell death in peripheral T-lymphocytes having the potential to inhibit leukocyte adhesion by direct binding to adhesion molecules. The aim of the present study was to analyse in a non-human primate model (cynomolgus monkeys) morphological changes within the microvasculature and the different cell-subpopulations upon ischemia/reperfusion after immunosuppressive treatment. Our results show a decrease of the tissue damage and WBC infiltration in muscular structures as well as a lower number of mononuclear cells in peripheral blood in the ATG-treated group compared to a non-treated control group. We may conclude that pATGs have a beneficial effect on the early mechanisms of ischemia/reperfusion injury.

Use of RNA arbitrarily primed PCR to identify genomic alterations in the digestive gland of the freshwater bivalve Unio tumidus at a contaminated site

The technique of RNA arbitrarily primed polymerase chain reaction (RAP-PCR) was developed to detect DNA damage and variations in gene expression in response to exposure to toxic compounds. This approach was tested on the freshwater bivalve Unio tumidus to explore the ability of RAP-PCR to detect effects induced by river sediment contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and metals. In a first step the primer concentration was optimized to obtain reproducible amplifications of both high- and low-molecular-weight products. Optimized conditions allowed us to detect variations corresponding to the loss of PCR products in some animals exposed at the contaminated site compared with the control. Our results for the RAP-PCR approach performed on separate animals in field studies showed that interindividual variations could correspond to DNA damage and/or variations in gene expression.

Xenotransplantation for liver therapy or: Can porcine hepatocytes generate physiological functions sufficient for a human patient in ALF?

Detailed knowledge about physiology, biochemistry and function is required before artificial liver devices using porcine hepatocytes may be used successfully. Improvement of cell culture conditions and tissue engineering may permit the generation of human hepatocytes as substitutes for grafts in a transplantation setting. The physiological functions of xenografts have to be compatible with those of the recipient. However, first observations indicate that most physiological interaction in widely divergent species combinations such as pig and man are considerably different. This may be crucial for the selection of a suitable organ, tissue or cell for a clinical set-up. These differences vary from organ to organ and cell to cell. Only very conservative molecules, like for example insulin or calcitonin function properly in both species, while others such as complement, albumin and erythropoietin do not fulfill their task properly or not at all.

In vivo microscopic assessment of microcirculatory changes in a concordant xenogeneic primate experimental set up

Organ transplantation is always connected with ischemia and thus reperfusion injury of the graft. One of the characteristics in this process is the temporary and permanent adherence of leukocytes to the endothelium of the graft. This cell-to-cell interaction allows the immunocompetent cells to interact in the sense of antigen recognition with mainly defect endothelial cells. It was the aim to study whether induction therapy with poly-clonal ATG's would reduce or even prohibit these early interactions.

MATERIAL AND METHODS

The distal extremities of cynomolgus monkeys were flushed via the femoral vessels and reperfused with ABO-compatible human heparinised blood of a hct of 30%. Microcirculation was observed applying intra-vital microscopy. The images taken by a CCD-camera are recorded on video tapes for later off line evaluation. pATG 1 is directed against jurkat cells, pATG 2 against human thymocytes. In controls the blood vessels were perfused with untreated blood. In groups 2 and 3 the blood was treated with the amount of the ATG's used in clinical therapy 15 min. prior to perfusion. The total ischemia time was 1 hour.

RESULTS

Five minutes after perfusion rolling was seen in the untreated animal, this increased to change into sticking after 30 min. The blood flow (RBC) in larger venoles remained almost normal. Both polyclonal ATG's inhibited the adhesion to a large extend.

CONCLUSION

Ischemia reperfusion results in increasing adherence of leukocytes in the described model. pATG's suppress this phenomenon completely. This suggests that pATG's contain a number of antibodies directed against various types of cell surface molecules which are involved in reperfusion injury and that pATG's have a favourable influence on the early I/R-mechanisms after organ transplantation and a protective action when used as pre-operative induction therapy.

Xenotransplantation: perspectives and limits

Xenotransplantation faces the dilemma of an unlimited supply of cells, tissues and organs on the one hand and severe obstacles and limits on the other. One reason for the limitations is that the source animal of choice, the pig, and the human recipient separated 90 million years ago during evolution, a time in which biological characteristics such as anatomy, physiology and immunology have had much time to drift far apart. The acceptance of such an evolutionary widely divergent organ, especially the heart of a pig, could evoke refusal of xenotransplantation in conservative and religious patients. New legal aspects of allocation of xenografts have therefore to be reflected upon and appropriate guidelines developed. Inquiries show, however, that the acceptance of all types of porcine organs would be high if the quality of life after receiving such a xenograft is comparable to that after receiving the same allograft. This individual benefit of a xenograft could lead to a disregard of the collective risk in terms of xenozoonoses, often presented as a catastrophic scenarium. Therefore, transplantation societies and ethics committees have published comments and even guidelines for handling future clinical xenotransplantation. All three monotheistic religions and Hinduism support the idea of saving and improving human life with the help of an animal organ.

Influence of ischemic time on hyperacute xenograft rejection of pig hearts in a working heart perfusion model with human blood

In xenotransplantation long ischemic time of grafts is supposed to have a marked influence on hyperacute rejection (HXR). We investigated the influence of different cold ischemic times on HXR of ex vivo "working pig hearts" perfused with human blood. Xenoreactive natural antibodies (XNAb) as a trigger of HXR were eliminated by Ig-Therasorb immunoadsorption (IA). Explanted Landrace pig hearts of group G1 and group G3 (with additional IA) underwent 4 h of cold ischemia prior to xenoperfusion. Control groups G2 and G4 (with IA) were kept ischemic for only 46.6 +/- 15.8 and 51.2 +/- 4.2 min, respectively. Ischemic time prolonged the perfusion time in our working heart model (G1: 356 +/- 46.1 min; G2: 125 +/- 31 min; P < 0.05). IA had no additional impact on perfusion time but was effective by itself. The heart weight increased fourfold more in G2 as compared to the other groups. IA without ischemia significantly improved cardiac output in G4 (G3: 198.8 +/- 15.4 mL/min; G4: 338.5 +/- 16.0 mL/min). Coronary flow in G2 was significantly lower than in G1 (G1: 157.9 +/- 9.15 mL/min; G2: 59.4 +/- 20.1 mL/min). Histological signs of HXR (light and electron microscopy) could be found in G2 in contrast to the other groups. Parameters of serological damage showed a minimum in G4 and the maximum in G2. In G1 XNAb were nearly equally eliminated immediately after the start of xenoperfusion as in IA groups G4 and G3. Four hours of ischemic time showed beneficial effects in preventing HXR, possibly caused by changes of the endothelial cell surface (for example, glycosylation or loss of alpha1-3Gal epitopes with a hapten effect).

Prevention of hyperacute xenograft rejection in orthotopic xenotransplantation of pig hearts into baboons using immunoadsorption of antibodies and complement factors

To prevent hyperacute xenograft rejection (HXR) caused by preformed natural antibodies (XNAb) after orthotopic heart xenotransplantation (oXHTx) of landrace pig hearts into baboons, we used immunoadsorption of immunoglobulins IgG, IgM and IgA and complement with the reusable Ig-Therasorb column. In addition to functional data, tissue was sampled for histological, immunohistochemical and electron microscopical analysis. We performed three oXHTx of landrace pig hearts to baboons using extracorporeal circulation (ECC) connected to the immunoadsorption unit. Intraoperative treatment consisted of four cycles of immunoabsorption (IA). One oXHTx of a baboon without IA served as a control. A mismatch of donor and recipient heart size was prevented by selecting a 30-40% lower body weight of donor pigs than recipients. Four cycles of IA removed more than 80% of IgG, IgM and IgA, 86% of antipig antibodies and 66% of complement factors C3 and C4 from plasma. The graft of the control animal failed after 29 min. Orthotopic xenotransplantation with IA was selectively terminated after 100 min, 11 h and 21 h, respectively without any histological signs of HXR in light and electron microscopy. After weaning off from ECC these donor xenografts showed sufficient function with normal ECG and excellent cardiac output in echocardiography and invasive measurement (1.93 +/- 0.035 l/min). The myocardium of the control xenograft demonstrated more deposits of Ig and complement components (C3, C4) than in the IA group. Baboons survive HXR after orthotopic pig heart xenotransplantation due to antibody depletion by reusable Ig-Therasorb column treatment. Long-term survival in an orthotopic baboon xenotransplantation model after IA, especially in combination with transgenic pig organs, could be a reliable preclinical trial for future clinical xenotransplantation programs.

Evaluation of a system for the perfusion of isolated, rodent organs

Perfusion of isolated organs is a common experimental approach. However, the surfaces of the perfusion system might alter the components of the blood and thereby negatively affect organ function. The aim of this study was to minimize the influence of the perfusion system on the blood components and to evaluate the system. Pressure and flow in the perfusion system consisting of a roller-pump, reservoir, oxygenator, hemo-filter and bubble-trap with a total tubing length of 4.5 m are controlled by a computer software (DASYLAB, Datalog, Moenchengladbach, Germany) via a transducer connected to the system. The organ to be perfused is positioned under a microscope (Orthoplan, Leica, Bensheim, Germany), allowing the investigation of microcirculatory parameters. The images raised are recorded on video tapes. To evaluate the system it was perfused with human blood (Hct 28 to 30%) for 90 min. Heparin (n = 6) or citrate (n = 6) served as anti-coagulants. The disappearance of cells from the blood was determined at time points 0, 1, 5, 10, 15, 20, 30, 45, 60, 75 and 90 min by means of a cell counter (AC T8, Coulter Beckmann, Krefeld, Germany). Cell activation was assessed by analysis of the expression of L- and P-selectin and CD11b. The activation of the complement system was examined by measuring the serum levels of the complement factors C3c and C4. There was no significant loss or activation of the blood cells at any of the above given time points. The serum levels of the complement factors remained within the physiological range and showed no changes throughout the whole experiments. Thus, the perfusion system does not have a negative influence on the blood and its individual components, and is therefore a reliable tool for perfusion experiments.

Chronic persistent knee pain after repeated diagnostic arthroscopy: osteoid osteoma, a primarily overlooked diagnosis in a young woman

We report a case of osteoid osteoma of the distal femur in an adolescent female patient that was primarily overlooked and led to repeated diagnostic arthroscopy of the knee. A thorough history and physical examination of the joint as well as adequate roentgenographic studies could have spared this patient two unnecessary arthroscopies and indicated the correct therapy.

Production of proinflammatory cytokines and adhesion molecules in ex-vivo xenogeneic kidney perfusion

Xenogeneic transplantation of solid organs is limited due to hyperacute rejection. In concordant systems, the mechanisms of rejection can be studied due to cross-reactivity of mediators with anti-human monoclonal antibodies. The aim of this study was to obtain information about the kinetics of proinflammatory cytokines and production of soluble adhesion molecules in the acute phase of reperfusion, eight kidneys from rhesus monkeys were perfused ex-vivo with human blood (group B/0) for 1 hour in a closed system. Blood levels of IL-1b, IL-6, TNFalpha, soluble ICAM, and E-selectin were measured using an ELISA technique under steady-state conditions. Cytokine levels rose significantly within the 60-min interval (IL-1b, 6.1 +/- 2.6-161.1 +/- 98.5 pg/ml; IL-6, 30.2 +/- 7.7-274.2 +/- 75.8 pg/ml; TNFalpha, 544.2 +/- 363.6-1651.0 +/- 25.7 pg/ml; P < 0.05). Immediately after the beginning of reperfusion, soluble ICAM-1 and selectin levels were abnormally high and rose constantly throughout the observation period, reaching significance at 60 min. High levels of proinflammatory cytokines may lead to an induction of adhesion molecules, thus, upregulating the leukocyte-endothelial interaction in a complement-independent mechanism. Specific pretreatment with monoclonal antibodies against ICAM-1, LFA-1, or other soluble mediators may be useful in down-regulating hyperacute rejection in trans-species transplantation.

Xenogeneic ex vivo hemoperfusion of rhesus monkey livers with human blood

In order to copy the clinical situation of concordant xenotransplantation, Rhesus Monkey livers were hemoperfused with human blood. Changes of immunological (TNFalpha, IL-1beta, IL-2, IL-2R, IL-6, IFNgamma, TXB2, 6kPGF1alpha, sICAM-1, sELAM-1, sHLA-I-Ag) and pathophysiological (GOT, GPT, LDH, CK) parameters were followed. Our experiment proves that all phenomena start in the first hour of xenogeneic blood circulation. Xenogeneic rejection in our concordant system is surprisingly severe. Preformed natural antibodies only cannot be the reason of such a damage. We think that beside other important immunological mechanisms, humoral mediators play a considerable role at the beginning of a xenogeneic rejection.

The prevention and treatment of vascular graft infection with a Triclosan (Irgasan)-bonded Dacron graft: an experimental study in the pig

OBJECTIVES

to evaluate the role of Triclosan (Irgasan(R)) in the prevention of prosthetic graft infection.

MATERIAL AND METHODS

fifty-one pigs were assigned randomly to six groups. Group I (graft) and II (graft and Triclosan) were control groups. Groups III (graft) and IV (grafts and Triclosan) were contaminated with 2 x 10(7)CFU/ml S. aureus. Groups V (graft) and VI (graft and Triclosan) were intraoperatively contaminated with 2 x 10(7)CFU/ml S. aureus and reoperated on after 7 days. Remaining animals were sacrificed on day 28. The end point of the investigation was vascular graft infection, defined as the bacteriological and/or histological proof of infection. Results in both control groups no vascular graft infections were detected in Groups I and II. All of the group III animals presented but none of the group IV developed a graft infection (p <0.02). All of the group V animals presented and 10 of 12 animals developed a graft infection.

CONCLUSION

in this animal model Triclosan bonding appears effective in preventing prosthetic graft infection. However, the in situ replacement of Triclosan-protected grafts was not successful in the treatment of graft infection.

Impact of Ig-Therasorb immunoapheresis on stability of xenogeneic ex vivo porcine liver perfusion--value of aminotransferases and flow rates for the assessment of metabolic graft viability

Due to growing shortage of donor organs, the concept of extracorporeal pig liver perfusion in the treatment of acute liver failure has been rediscovered. Immunomodulation, such as immunoapheresis or inhibition of complement, results in long-term perfusion without exact knowledge of the remaining metabolic graft viability. This study was aimed at the comparison of conventional parameters of graft stability such as perfusion rates and release of aminotransferases with parameters of metabolic graft function. Ig-Therasorb immunoapheresis (IA) of the xenogeneic perfusate was performed to protect the discordant pig livers from hyperacute rejection, mediated by preformed naturally occurring human xenogeneic antibodies. The application of IA created stable autologous graft reperfusion after a short time of xenoperfusion, but it was not able to prevent the livers from severe synthetic and functional damage. In the future, improvement of xenogeneic graft function, rather than pure prolongation of perfusion, must be the principal aim.