A nationwide registry study to compare bleeding rates in patients with atrial fibrillation being prescribed oral anticoagulants

Aims

We aimed to evaluate bleeding risk in clinical practice in patients with atrial fibrillation (AF) being prescribed dabigatran, rivaroxaban, or apixaban compared with warfarin.

Methods

Using nationwide registries (Norwegian Patient Registry and Norwegian Prescription Database), we identified AF patients with a first prescription of oral anticoagulants between January 2013 and June 2015. Patients were followed until discontinuation or switching of oral anticoagulants, death, or end of follow-up. The primary endpoint was major or clinically relevant non-major (CRNM) bleeding.

Results

In total 32 675 AF patients were identified (58% men, median age 74 years): 11 427 patients used warfarin, 7925 dabigatran, 6817 rivaroxaban, and 6506 apixaban. After a median follow-up of 173 days (25th, 75th percentile 84, 340), 2081 (6.37%) patients experienced a first major or CRNM bleeding. Using a Cox proportional hazard model adjusting for baseline characteristics, use of apixaban [hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.61–0.80, P < 0.001] and dabigatran (HR 0.74, 95% CI 0.66–0.84, P < 0.001) were associated with a lower risk of major or CRNM bleeding compared with warfarin whereas use of rivaroxaban was not (HR: 1.05, 95% CI 0.94–1.17, P = 0.400). Use of dabigatran and rivaroxaban were associated with higher risk of gastrointestinal bleeding, whereas use of apixaban and dabigatran were associated with lower risk of intracranial bleeding, compared with warfarin.

Conclusion

In this nationwide cohort study in AF patients, apixaban and dabigatran were associated with a lower risk of major or CRNM bleeding compared with warfarin. The risk of gastrointestinal bleeding was higher with rivaroxaban and dabigatran compared with warfarin.

Endomyocardial, intralymphocyte, and whole blood concentrations of ciclosporin A in heart transplant recipients

Background

In the early phases following heart transplantation a main challenge is to reduce the impact of acute rejections. Previous studies indicate that intracellular ciclosporin A (CsA) concentration may be a sensitive acute rejection marker in renal transplant recipients. The aims of this study were to evaluate the relationships between CsA concentrations at different target sites as potential therapeutic drug monitoring (TDM) tools in heart transplant recipients.

Methods

Ten heart transplant recipients (8 men, 2 women) on CsA-based immunosuppression were enrolled in this prospective single-center pilot study. Blood samples were obtained once to twice weekly up to 12 weeks post-transplant. One of the routine biopsies was allocated to this study at each sampling time. Whole blood, intralymphocyte, and endomyocardial CsA concentrations were determined with validated HPLC-MS/MS-methods. Mann–Whitney U test was used when evaluating parameters between the two groups of patients. To correlate whole blood, intralymphocyte, and endomyocardial CsA concentrations linear regression analysis was used.

Results

Three patients experienced mild rejections. In the study period, the mean (range) intralymphocyte CsA trough concentrations were 10.1 (1.5 to 39) and 8.1 (1.3 to 25) ng/10⁶ cells in the rejection and no-rejection group, respectively (P=0.21). Corresponding whole blood CsA concentrations were 316 (153 to 564) and 301 (152 to 513) ng/mL (P=0.33). There were no correlations between whole blood, intralymphocyte, or endomyocardial concentrations of CsA (P >0.11).

Conclusions

The study did not support an association between decreasing intralymphocyte CsA concentrations and acute rejections. Further, there were no association between blood concentrations and concentrations at sites of action, potentially challenging TDM in these patients.

Urinary proteomic shotgun approach for identification of potential acute rejection biomarkers in renal transplant recipients

BACKGROUND

Acute rejection (AR) episodes in renal transplant recipients are suspected when plasma creatinine is elevated and other potential causes out ruled. Graft biopsies are however needed for definite diagnosis. Non-invasive AR-biomarkers is an unmet clinical need. The urinary proteome is an interesting source in the search for such a biomarker in this population.

METHODS

In this proof of principle study, serial urine samples in the early post transplant phase from 6 patients with biopsy verified acute rejections and 6 age-matched controls without clinical signs of rejection were analyzed by shotgun proteomics.

RESULTS

Eleven proteins fulfilled predefined criteria for regulation in association with AR. They presented detectable regulation already several days before clinical suspicion of AR (increased plasma creatinine). The regulated proteins could be grouped by their biological function; proteins related to growth and proteins related to immune response. Growth-related proteins (IGFBP7, Vasorin, EGF and Galectin-3-binding protein) were significantly up-regulated in association with AR (P = 0.03) while proteins related to immune response (MASP2, C3, CD59, Ceruloplasmin, PiGR and CD74) tended to be up-regulated ( P = 0.13).

CONCLUSION

The use of shotgun proteomics provides a robust and sensitive method for identification of potentially predictive urinary biomarkers of AR. Further validation of the current findings is needed to establish their potential clinical role with regards to clinical AR diagnosis.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT00139009.

A population pharmacokinetic model of ciclosporin applicable for assisting dose management of kidney transplant recipients

BACKGROUND AND OBJECTIVE

The pharmacokinetic disposition of ciclosporin shows great intra- and interpatient variability, and that combined with a narrow therapeutic window makes therapeutic drug monitoring of ciclosporin necessary. The nonlinear mixed-effects population pharmacokinetic program NONMEM predicts individual pharmacokinetic parameters based not only on individual patient observations but also on population characteristics and the patient's covariates. The aim of this model development is to potentially use it in the clinical setting to optimize ciclosporin dosing in renal transplant recipients.

METHODS

A population pharmacokinetic model of ciclosporin has been developed with NONMEM using full 12-hour pharmacokinetic profiles from 29 renal transplant recipients, 3 months of daily follow-up data from an additional 11 recipients, and both 3 months of follow-up data and full 12-hour pharmacokinetic profiles from nine patients. The internal validation of the model was based on data splitting and jack-knife methods. In addition, the model was validated for its clinical applicability on standard trough and 2-hour post-dose concentration data from 12 additional patients with 3 months of follow-up.

RESULTS

The model that best described the ciclosporin data was a two-compartment model with first-order absorption process with lagged time. The population pharmacokinetic parameters were oral clearance (CL/F) = 26.9 L/h; central volume of distribution after oral administration (V(1)/F) = 24.4 L; absorption rate constant (k(a)) = 0.544 h-1; lag time = 0.460 h; peripheral volume of distribution = 1119 L and intercompartmental clearance after oral administration (Q/F) = 19.6 L/h. Three covariates had significant effect on a total of six pharmacokinetic parameters. These were bodyweight on V(1)/F and k(a), time after transplantation on k(a), and age on CL/F, k(a) and V(1)/F. Cytochrome P450 3A5 genotype was also a significant covariate but was not included in the final model since such information is not available in clinical practice. The external validation showed that the model was able to predict ciclosporin concentrations in the 12 new patients with an average predictive error of 17.4 +/- 14% when the standard sample concentrations from the previous week were given.

CONCLUSION

A NONMEM pharmacokinetic model for ciclosporin in renal transplant recipients was successfully developed and validated for the first 3 months post-transplantation. The model showed good predictability in a new patient cohort. After further clinical validation, the model may be applicable as a clinical tool for optimizing ciclosporin dosing in renal transplant recipients in the early post-transplant period.

Cinacalcet's effect on the pharmacokinetics of tacrolimus, cyclosporine and mycophenolate in renal transplant recipients

BACKGROUND

The calcimimetic drug cinacalcet offers a novel therapeutic option to treat post-transplant hypercalcemia and hyperparathyroidism; however, the interaction with calcineurin inhibitors and mycophenolate has not been evaluated.

METHODS

In the present study the effects of cinacalcet on the pharmacokinetics of cyclosporine A (CsA), tacrolimus (Tac) and mycophenolate were investigated in 14 renal transplant recipients with stable renal function (mean creatinine 126.4 +/- 45.3 micromol/L). The patients were treated with either CsA (n = 8) or Tac (n = 6) in combination with mycophenolate/azathioprine and steroids. Twelve-hour pharmacokinetic investigations to measure CsA and its six main metabolites, Tac and mycophenolate concentrations were performed before and after 1-week treatment with 30 mg cinacalcet once daily.

RESULTS

Cinacalcet treatment induced a significant 14.3 +/- 12.1% decrease in Tac AUC(0-12) (P = 0.039). Tac C(max), T(max) and T(1/2) also tended to decrease. The pharmacokinetics of CsA and mycophenolate were not significantly affected by concomitant treatment with cinacalcet. However, the secondary CsA metabolite, AM19, showed a significant increase of 9.0 +/- 9.5% during cinacalcet treatment (P = 0.040). Renal function decreased significantly from 78 +/- 11 to 72 +/- 12 mL/min (P = 0.019) and correlated with the increased levels of metabolite AM19 in the CsA group. Renal function was unchanged in the Tac group.

CONCLUSION

Cinacalcet treatment showed a moderate effect on the Tac, but not CsA or mycophenolate, pharmacokinetics after 1-week concomitant treatment. This interaction appears to have minor clinical relevance. However, it is advisable to monitor renal function in CsA-treated patients due to the observed decrease in renal function.

Determination of ciclosporin A and its six main metabolites in isolated T-lymphocytes and whole blood using liquid chromatography–tandem mass spectrometry

A specific and sensitive method for determination of intracellular ciclosporin A (CsA) and its six main metabolites AM1, AM9, AM1c, AM1c9, AM19 and AM4N, in isolated T-lymphocytes and whole blood is described. T-lymphocytes were separated from whole blood using Prepacyte. The analytes were extracted and purified from isolated lymphocytes and whole blood by protein precipitation followed by solid-phase extraction (SPE). The analytes and the internal standard, ciclosporin C (CsC), were separated on a reversed phase C8 column (30 mm x 2.1mm, 3 microm) with a 10 mm x 2 mm, 5 microm Drop-In Guard Cartridge, using gradient elution chromatography and tandem ion trap mass spectrometry detection. The method has been validated in accordance with FDA guidelines and showed linear range from 0.25 to 500 ng/mL for CsA, 0.5 to 500 ng/mL for AM1, AM9 and AM19, 1 to 500 ng/mL for AM4N, AM1c and AM1c9 in intracellular matrix, and 2.5 to 3000 ng/mL for all analytes in whole blood. The applicability of the method is shown on patient samples.

Cranial neural crest cells contribute to connective tissue in cranial muscles in the anuran amphibian, Bombina orientalis

The contribution of cranial neural crest cells to the development and patterning of cranial muscles in amphibians was investigated in the phylogenetically basal and morphologically generalized frog, Bombina orientalis. Experimental methods included fluorescent marking of premigratory cranial neural crest and extirpation of individual migratory streams. Neural crest cells contributed to the connective tissue component, but not the myofibers, of many larval muscles within the first two branchial arches (mandibular and hyoid), and complex changes in muscle patterning followed neural crest extirpation. Connective tissue components of individual muscles of either arch originate from the particular crest migratory stream that is associated with that arch, and this relationship is maintained regardless of the segmental identity-or embryonic derivation-of associated skeletal components. These developmental relations define a pattern of segmentation in the head of larval anurans that is similar to that previously described in the domestic chicken, the only vertebrate that has been thoroughly investigated in this respect. The fundamental role of the neural crest in patterning skeleton and musculature may represent a primitive feature of cranial development in vertebrates. Moreover, the corresponding developmental processes and cell fates appear to be conserved even when major evolutionary innovations-such as the novel cartilages and muscles of anuran larvae-result in major differences in cranial form.

Cranial neural crest cell migration in the Australian lungfish, Neoceratodus forsteri

A crucial role for the cranial neural crest in head development has been established for both actinopterygian fishes and tetrapods. It has been claimed, however, that the neural crest is unimportant for head development in the Australian lungfish (Neoceratodus forsteri), a member of the group (Dipnoi) which is commonly considered to be the living sister group of the tetrapods. In the present study, we used scanning electron microscopy to study cranial neural crest development in the Australian lungfish. Our results, contrary to those of Kemp, show that cranial neural crest cells do emerge and migrate in the Australian lungfish in the same way as in other vertebrates, forming mandibular, hyoid, and branchial streams. The major difference is in the timing of the onset of cranial neural crest migration. It is delayed in the Australian lungfish in comparison with their living sister group the Lissamphibia. Furthermore, the delay in timing between the emergence of the hyoid and branchial crest streams is very long, indicating a steeper anterior-posterior gradient than in amphibians. We are now extending our work on lungfish head development to include experimental studies (ablation of selected streams of neural crest cells) and fate mapping (using fluoresent tracer dyes such as Dil) to document the normal fate as well as the role in head patterning of the cranial neural crest in the Australian lungfish.

PDGFB regulates the development of the labyrinthine layer of the mouse fetal placenta

PDGFB is a growth factor which is vital for the completion of normal prenatal development. In this study, we report the phenotypic analysis of placentas from mouse conceptuses that lack a functional PDGFB or PDGFRbeta gene. Placentas of both types of mutant exhibit changes in the labyrinthine layer, including dilated embryonic blood vessels and reduced numbers of both pericytes and trophoblasts. These changes are seen from embryonic day (E) 13.5, which coincides with the upregulation of PDGFB mRNA levels in normal placentas. By E17, modifications in shape, size, and number of the fetal blood vessels in the mutant placentas cause an abnormal ratio of the surface areas between the fetal and the maternal blood vessels in the labyrinthine layer. Our data suggest that PDGFB acts locally to contribute to the development of the labyrinthine layer of the fetal placenta and the formation of a proper nutrient-waste exchange system during fetal development. We point out that the roles of PDGFB/Rbeta signaling in the placenta may be analogous to those in the developing kidney, by controlling pericytes in the labyrinthine layer and mesangial cells in the kidney.

Neurotrophin-7: a novel member of the neurotrophin family from the zebrafish

A novel member of the neurotrophin family, zebrafish neurotrophin-7 (zNT-7), was isolated from the zebrafish Danio rerio. The amino acid sequence of zNT-7 is more closely related to that of fish nerve growth factor (NGF) and neurotrophin-6 (NT-6) than to that of any other neurotrophin. zNT-7 is, however, equally related to fish NGF and NT-6 (65% and 63% amino acid sequence identity, respectively) indicating that it represents a distinct neurotrophin sequence. zNT-7 contains a 15 amino acid residue insertion in a beta-turn region in the middle of the mature protein. Recombinant zNT-7 was able to bind to the human p75 neurotrophin receptor and to induce tyrosine phosphorylation of the rat TrkA receptor tyrosine kinase, albeit less efficiently than rat NGF. zNT-7 did not interact with rat TrkB or TrkC, indicating a similar receptor specificity as NGF. We propose that a diversification of the NGF subfamily in the neurotrophin evolutionary tree occurred during the evolution of teleost fishes which resulted in the appearance of several additional members, such as zNT-7 and NT-6, structurally and functionally related to NGF.

Characterization of human neutrophils adherent to organic polymers

The adherence of human neutrophils to surfaces from organic polymers (Pellethane, two types of polyvinyl chloride (PVC), polypropylene and polyethylene) is associated to a different extent with O2- formation. No comparable differences were observed for the liberation of the granular enzyme elastase. Only cells attached to Pellethane responded strongly after a second stimulation by opsonized zymosan, N-formyl-methionyl-leucyl-phenylalanine (FMLP) and aggregated IgG. The expression of related antigens on adherent cells was measured by a cell-ELISA (enzyme-linked immunosorbent assay). Cells adherent to five various untreated organic polymers show no differences of their Fc gamma- and C3bi-receptors. A considerable increase of all investigated cellular antigens was observed for neutrophils adherent to films precoated with autologous plasma. The adherence rates and the viability for cells adherent to different materials were similar and may not account for the observed differences in O2- production during the primary adherence reaction and a further secondary stimulation.

[Analysis of T-cell subpopulations and expression patterns of lymphocytic activation markers in patients in the early phase following kidney transplantation using laser flow cytometry]

In 10 patients after kidney transplantation the T cell subpopulations (CD4, CD8) and the number of activated lymphocytes (IL-2R and transferrin receptor+, 4F2+, HLA-DR+, CD3+) in the peripheral blood were determined. In 9 out of 9 cases with rejection a clear immune activation could observed. In patients with CMV-associated rejection crisis the CD4/CD8 ratio was significantly higher compared with patients with rejection crisis but without CMV infection. In all patients with CMV infection (n = 5) an increase of activated lymphocytes was observed. In a clinical-immunological monitoring the dynamics of the CD4/CD8 ratio, the expression of activation marker (especially CD3+, HLA-DR+ and 4F2+) and the absolute number of lymphocyte subpopulations should included.

The influence of interferon-gamma and various phagocytic stimuli on the expression of MHC-class II antigens on human monocytes--relation to the generation of reactive oxygen intermediates

Human monocytes show a dose-dependent decrease of the MHC-class II antigen expression (HLA-DR and HLA-DQ) after addition of zymosan or Staphylococcus aureus Cowan I particles. Interferon-gamma did not prevent this process. The expression of MHC-class I antigens was not affected. The dose-response and kinetic curves showed individual differences. An association between the capacity to form reactive oxygen intermediates and the downregulation of MHC-class II antigen expression was observed. In addition, after digestion of the phagocytosed particles interferon-gamma could restore the MHC-class II antigen expression on the cultured monocytes. The possible biological significance of these interactions between interferon-gamma and phagocytosis for the function of monocytes/macrophages in the local inflammatory process is discussed.

The influence of phagocytic stimuli on the expression of HLA-DR antigens; role of reactive oxygen intermediates

Human peripheral blood mononuclear cells show after one day of culture with opsonized zymosan a decreased expression of HLA-DR (but not HLA-A, B, C) antigens, which can be prevented by the scavenger of reactive oxygen intermediates beta-carotene, or superoxide dismutase or indomethacin. Mononuclear cells of a patient with a heterozygous form of chronic granulomatous disease show no alterations in HLA-DR antigen expression after culture with opsonized zymosan. Possible roles of reactive oxygen intermediates or prostaglandins in the modulation of HLA-DR antigens are discussed.

Histamine and immune reactions. 3. Inhibition of early events of human lymphocyte activation by histamine

Histamine inhibits the chemiluminescence response of human lymphocytes to Concanavalin A by interfering with early triggering events. The inhibition seems to be mediated via H2 receptors, acts immediately, and is reversible by washing. A longer incubation in a histamine-containing medium induces a refractory state of the cells. The inhibitory effect described here is compared with the inhibitory action of histamine in the lymphocyte transformation test.

Circulating immune complexes after cadaver kidney transplantation

351 sera from 27 human recipients of renal allografts and 21 healthy blood donors were assayed for circulating immune complexes by the Clq solid-phase radioimmune assay. Increased Clq-binding activity (Clq-BA) was detected in pretransplant sera from 5 patients with chronic pyelonephritis (PN) and 3 patients with chronic glomerulonephritis (GN). A significant decrease of Clq-BA immediately after transplantation could not be found. 6 weeks after transplantation only 2 patients of the PN group showed increased Clq-BA. Serial studies in 17 patients with rejection crises did not show any correlation between the level of serum Clq-BA and the occurrence of rejections. Furthermore, no correlation could be found between the occurrence of complement-dependent lymphocytotoxic antibodies measured by the 51Cr release technique and the level of serum Clq-BA. In contrast, our results show that the probability of graftectomy or graft failure is significantly higher, at least in the early phase after transplantation, when the serum Clq-BA is lowered for several weeks.

[Radioimmunological detection of soluble immune complexes in serum (author's transl)]

Immune complexes could be measured in sera with the use of plastfixed Clq and 125J-labeled anti-Ig-antibody. The sensitivity of the system is 0.1 microgram aggregated human IgG, the working range is between 0.1 and 10 micrograms per 0.5 ml. In 58% of the sera from patients with systemic lupus erythematosus was found an increase in the immune complex content.