Biomedical subjects

Michele Kessler

Publications and source records attributed to Michele Kessler.

4 recordsLinked to original sources

PubMed2006

Immunogenicity of biopharmaceuticals.

The availability of biopharmaceuticals has been increasing over the past decade and as their patents expire, the emergence of biosimilar agents approaches. The primary issue of concern for the safety of these agents is the potential for immunogenicity. Both product- and host-related factors have documented impact on the immune response, but many factors are still unknown. Although in many cases the presence of antibodies may have little clinical consequence, the upsurge of pure red cell aplasia cases further increased concerns about potential clinical consequences of extensive use of biopharmaceuticals and biosimilars. Available laboratory measurement methods are insufficient to predict biological and clinical properties of biopharmaceuticals, or even to compare their bioequivalence. Comparison of results from different studies is complicated by the variability of assay measurements, presentation of data and lack of standardization.

Animals↗

PubMed2005

Corticosteroid-free immunosuppression with tacrolimus, mycophenolate mofetil, and daclizumab induction in renal transplantation.

BACKGROUND: Corticosteroid-free maintenance immunosuppression after organ transplantation eliminates the well-known corticosteroid-related side effects and may help to improve long-term outcome. We investigated whether a corticosteroid-free tacrolimus (Tac)/mycophenolate mofetil (MMF) regimen, in combination with daclizumab (Dac) induction therapy, provides adequate immunosuppression after renal transplantation. METHODS: This 6-month, open-label, multicenter, parallel-group study involved 538 renal patients randomized (1:1) to a Dac/Tac/MMF regimen (n = 260) or a Tac/MMF/corticosteroids regimen (n = 278) as a control group. RESULTS: Of the patients who completed the study, 88.8% in the Dac/Tac/MMF group were free from corticosteroid therapy at month 6. The incidence of biopsy-proven acute rejection was 16.5% in both treatment groups; the incidence of biopsy-proven corticosteroid-resistant acute rejection was 4.3% and 5.0% with Tac/MMF/corticosteroids and Dac/Tac/MMF, respectively (P = NS for both comparisons). Renal function was also similar in both groups: median serum creatinine at month 6 was 125.0 micromol/L (Tac/MMF/corticosteroids) and 131.0 microml/L (Dac/Tac/MMF), P = 0.277. The overall safety profile was similar with both regimens. However, compared with the Tac/MMF/steroid regimen, a significantly reduced incidence of new-onset insulin-dependent diabetes mellitus (5.4% vs. 0.4%, P = 0.003) was found with steroid-free immunosuppression. Moreover, mean total cholesterol concentrations increased from baseline in the Tac/MMF/corticosteroids group by 0.19 mmol/L, whereas in the Dac/Tac/MMF group, levels decreased by 0.19 mmol/L, P = 0.005. CONCLUSIONS: Corticosteroid-free immunosuppression with a Dac/Tac/MMF regimen is as effective at preventing acute rejection after renal transplantation as a standard triple regimen of Tac/MMF/corticosteroids. Furthermore, the safety benefits reported with Dac/Tac/MMF treatment may help improve the long-term outcome for renal-transplant patients.

Adolescent↗

PubMed2003

Kidney warming during transplantation.

The objective of the present study was to describe kidney temperature variations during transplantation and to identify the factors responsible for kidney warming. Kidney temperature was recorded steadily during transplantation. Kidney weight, body mass index (BMI), second warm ischemia time (t), and kidney temperature at the time of being placed in the recipient were analyzed so that we could evaluate their influence on kidney temperature and on kidney warming during transplantation. Kidney temperature at the time of removal from the container was 1.6 degrees C and 6. 3 degrees C when the kidney was placed in the recipient. Kidney temperature in the recipient depended on kidney temperature after serum washing (P<0.0001), but was independent of kidney preparation time (P=0.94). Then, kidney temperature (T) increased according to the logarithmic curve given in the following equation: T=7.2 ln(t)-0.6. Kidney temperature at the end of anastomosis was 26.7 degrees C. Kidney warming speed was 0.48 degrees/min and was dependent on the length of time of vascular anastomosis (P<0.0001). Kidney weight decreased the kidney warming speed (P=0.02). In conclusion, kidney warming increases slowly during ex vivo preparation. Kidney temperature stays below the damaging ischemic temperature of 18 degrees C. Because of its major impact on kidney warming, it is desirable that vascular anastomosis time be reduced, and, consequently, ex vivo kidney preparation needs to be meticulous.

Adolescent↗

PubMed2003

Anti-HBs cellular immune response in kidney recipients before and 4 months after transplantation.

Patients with renal failure represent a population at risk for hepatitis B, since only 50 to 60% of them develop protective humoral responses after vaccination. As this could be due to an altered regulation of cellular immune responses, the objectives of the present study were to evaluate the proliferative abilities of lymphocytes from patients with chronic renal failure after stimulation in vitro with a mitogen (pokeweed mitogen [PWM]) or HBsAg. In order to differentiate between the immunodeficiency associated with renal failure and that due to immunosuppression posttransplantation, the same subjects were tested before and 4 months after kidney transplantation. The lymphoproliferation assay used was performed by flow cytometry, which is based on sequential analysis of the cell cycle and which allows analysis of cytokine production. Serologically, the group of 36 patients tested comprised 22% nonresponders, 30% poor responders, and 48% responders. Lymphocyte growth was observed for all patients after stimulation with PWM, indicating that these cells had the capacity to proliferate in vitro. The level of lymphoproliferation in response to PWM was significantly reduced after transplantation, yet both before and after transplantation, all serologic nonresponders developed cellular responses to at least two vaccines. No correlation between humoral and cellular responses was shown. Proliferating cells were lymphocytes, which mostly secreted interleukin 4 (IL-4) and IL-10 for the three serologic groups. This study suggests that even when repeated vaccination fails to induce significant antibody levels in patients with renal failure, specific HBs cellular responses develop, and these may prove to be efficient in protecting these patients against hepatitis B.

Adult↗