1,721,029 research outputs found

    Identifying risk profiles in liver transplant candidates and implications for induction immunosuppression

    No full text
    Changes in recipient and donor characteristics are redefining the role of induction in liver transplant recipients. Older recipients are more common, with greater concomitant comorbidity. Moderate or severe renal dysfunction is now estimated to affect 40% of liver transplant recipients. Donors are also becoming older, and other factors such as more frequent non-alcoholic fatty liver disease (NAFLD) compromise the quality of some grafts. Rejection rates are now relatively low (-10%) but some patients have a markedly increased risk such as younger recipients and those undergoing re-transplantation. Induction immunosuppression is associated with a significant reduction in rejection risk but due to various factors universal induction is not justified. Steroid-free therapy without induction increases the risk of biopsy-proven acute rejection (BPAR) but randomized trials have shown that induction with an interleukin-2 antagonist receptor (IL-2RA) agent or with rabbit antithymocyte globulin (rATG) maintains immunosuppressive efficacy in steroid-free regimens. Delayed calcineurin inhibitor (CNI) initiation (e.g. to days 4-5 post transplant) can prevent deterioration of renal function during the first year post-transplant, but requires induction with an IL-2RA agent or rATG to maintain early immunosuppressive efficacy.IL-2RA induction may be inadequate to ensure a low risk of rejection in a steroid-free regimen combined with delayed tacrolimus. Randomized trials of CNI withdrawal at month 1 post-transplant have only achieved an acceptable rate of BPAR when induction is administered. In terms of safety, an increased rate of infection does not seem to be a concern. The most recent large-scale analyses have not indicated any evidence for an increased risk of malignancy, or specifically post-transplant lymphoproliferative disease. In summary, the place of induction in the management of liver transplant patients is becoming established. Selective use in high-risk individuals to avoid graft rejection is still relevant, but the key rationale for induction is to facilitate steroid-sparing and CNI-sparing regimens to reduce long-term complications. (C) 2018 The Authors. Published by Elsevier Inc

    In-vivo 31 P Magnetresonanzspektroskopie bei repetitiver transarterieller Chemoembolisation maligner Lebertumoren

    Full text link
    Mit der palliativen transarteriellen Chemoembolisation (TACE) läßt sich eine Verkleinerung von malignen Lebertumoren und eine Verlängerung des Überlebens erreichen. Im Verlauf des Therapiezyklus diente die Phosphor-Magnetresonanzspektroskopie mittels Chemical-Shift-Imaging einem nichtinvasiven Einblick in den zellulären Energie- und Membranstoffwechsel. Eine Differenzierung zwischen primären und sekundären Lebertumoren war anhand der 31P-Spektren nicht möglich. Posttherapeutisch zeigten die Patienten einen Anstieg des anorganischen Phosphats bei Abfall des ß-NTP-Signals, die sich während des sechswöchigen Intervalls vor der nächsten Intervention wieder normalisierten. Therapieansprechen und -versagen zeigten während des Therapiezyklus unterschiedliche spektroskopische Quotientenverläufe. Eine deutliche Volumenreduktion als auch eine homogene und dauerhafte Lipiodoleinlagerung im Tumor gehen zuverlässig mit einem spektroskopischen Therapieansprechen einher. Dies zeigte sich bei der ersten Patientengruppe während der Untersuchung direkt nach der Embolisation und bei der zweiten Gruppe erst vor der nächsten Intervention. Therapieversagen, Tumorprogression und geringe Lipiodoleinlagerung bzw. rasche Entspeicherung im Verlauf ließen sich spektroskopisch nach-weisen. Schwierig bleibt die Zuordnung der Patienten mit uneinheitlichen Quotienten-verläufen. Die MRS kann früher als die klinische Routinediagnostik eine Aussage über das Therapieansprechen treffen. Für den Patienten ergibt sich die Vermeidung einer ineffektiven Therapie. Bei nachgewiesenem Ansprechen hingegen profitiert der Patient durch die wiederholte Anwendung der TACE. Der hohe personelle, technische und zeitliche Aufwand für die Phosphorspektroskopie verhindert bisher den klinischen Routineeinsatz dieses Verfahrens. Im Rahmen der klinischen Forschung, insbe-sondere in der onkologischen Therapiekontrolle, hat die MRS als nichtinvasive Methode heute einen großen Stellenwert.Using palliative transarterial chemoembolization (TACE) a reduction of malignant liver neoplasms and a prolongation of survival time can be achieved. During the course of therapy phosphorous magnetic resonance spectroscopy by means of chemical-shift-imaging was used for noninvasive examination of the cellular metabolism of energy and membranes. Differentiation between primary and secondary liver tumors was not feasible using 31P-spectra. After therapy patients had shown increased inorganic phosphate signal and reduction of the ß-NTP-signals, which normalized during six week intervall before next intervention. Response and non-response to therapy showed different courses of spectroscopic quotients during therapy cycle. Prominent reduction of volume as well as homogeneous and continous retention of lipiodol within the tumor are reliable combined with spectroscopic response to therapy. The first group of patients showed these signs at the examination immediately after embolization whereas patients of the second group showed these signs not before next intervention. Failure of therapy, progression of tumor and slight retention of lipiodol or rapid elemination during course of therapy were detectable by spectroscopy. Categorization of patients with non-uniform courses of quotients remains difficult. Magnetic resonance spectroscopy is able to determine response to therapy earlier than standard diagnostic methods. As a result ineffective therapy is avoided for the patient. On the other hand the patient profits from repeated administration of TACE. Great expense of personnel, equipment and time so far prevents clinical use of phosphorous spectroscopy as a matter of routine. In conjunction with clinical research MRS is an important non-invasive method especially for oncological therapy monitoring

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
    corecore