- Serial blood volume estimation in rabbits using trivalent chromium - An exploratory study. [Journal Article]
- MMethodsX 2019; 6:1068-1071
- Though often used in cardiac intensive monitoring set up, simultaneous evaluation of several variables like CVP, PCWP, SVV and hTEE for fluid volume resuscitation (especially when capillary permeabil…
Though often used in cardiac intensive monitoring set up, simultaneous evaluation of several variables like CVP, PCWP, SVV and hTEE for fluid volume resuscitation (especially when capillary permeability is major problem than cardiac performance) is a major challenge in many ICU setups. Therefore, repetitive determination of blood volume by trivalent chromium [51Cr (III)] as a direct single variable method may be a near ideal method during fluid volume resuscitation in cases where capillary permeability is a major problem (e.g. Burns). Hence, in the present article the repeatability and reliability of 51Cr (III) method in New Zealand white rabbits was explored. Mean blood volume values of initial measurement were 195.66 ± 47.30 ml or 89.81 ± 17.88 ml/kg body weight. Repeated mean blood volume values, measured after 1 h, was 181.98 ± 53.16 ml or 83.68 ± 22.09 ml/kg body weight. The average difference between the initial and repeated measurements was 10.93 ml (95% CI -3.33, 25.19 ml), which is not statistically significant (P = 0.128). The method using 51Cr (III) for repeat blood volume measurements after sixty minutes in rabbits is a reliable method. •Rapid•Repeatable•Reliable.
- Tumor-Specific Reactive Oxygen Species Accelerators Improve Chimeric Antigen Receptor T Cell Therapy in B Cell Malignancies. [Journal Article]
- IJInt J Mol Sci 2019 May 18; 20(10)
- Chimeric antigen receptor T cell (CART) therapy is currently one of the most promising treatment approaches in cancer immunotherapy. However, the immunosuppressive nature of the tumor microenvironmen…
Chimeric antigen receptor T cell (CART) therapy is currently one of the most promising treatment approaches in cancer immunotherapy. However, the immunosuppressive nature of the tumor microenvironment, in particular increased reactive oxygen species (ROS) levels, provides considerable limitations. In this study, we aimed to exploit increased ROS levels in the tumor microenvironment with prodrugs of ROS accelerators, which are specifically activated in cancer cells. Upon activation, ROS accelerators induce further generation of ROS. This leads to an accumulation of ROS in tumor cells. We hypothesized that the latter cells will be more susceptible to CARTs. CD19-specific CARTs were generated with a CD19.CAR.CD28.CD137zeta third-generation retroviral vector. Cytotoxicity was determined by chromium-51 release assay. Influence of the ROS accelerators on viability and phenotype of CARTs was determined by flow cytometry. The combination of CARTs with the ROS accelerator PipFcB significantly increased their cytotoxicity in the Burkitt lymphoma cell lines Raji and Daudi, as well as primary chronic lymphocytic leukemia cells. Exposure of CARTs to PipFcB for 48 h did not influence T cell exhaustion, viability, or T cell subpopulations. In summary, the combination of CARTs with ROS accelerators may improve adoptive immunotherapy and help to overcome tumor microenvironment-mediated treatment resistance.
- Reexamination of the chromium-51-labeled posttransfusion red blood cell recovery method. [Journal Article]
- TTransfusion 2019 Apr 19
- CONCLUSIONS: Sources of measurement error are inherent in the chromium-51 PTR method. Transfusion of an entire unlabeled RBC unit, followed by quantifying extravascular hemolysis markers, may more accurately measure true posttransfusion RBC recovery.
- Distinguishing essential thrombocythemia JAK2V617F from polycythemia vera: limitations of erythrocyte values. [Journal Article]
- HHaematologica 2019 Apr 04
- Distinguishing essential thrombocythemia JAK2V617F from polycythemia vera is difficult because of shared mutation and phenotypic characteristics. The World Health Organization suggested hemoglobin an…
Distinguishing essential thrombocythemia JAK2V617F from polycythemia vera is difficult because of shared mutation and phenotypic characteristics. The World Health Organization suggested hemoglobin and hematocrit values to diagnose polycythemia vera, but their sensitivity and specificity were not tested. Moreover, red cell values do not accurately predict red cell mass, which we use to discriminate essential thrombocythemia JAK2V617F from polycythemia vera. 83 polycythemia vera and 39 essential thrombocythemia JAK2V617F patients were diagnosed based on JAK2V617F positivity, chromium-51 red cell mass, and marrow biopsy findings. Red cell values used to construct a receiver operating characteristic analysis determined optimal thresholds for distinguishing essential thrombocythemia JAK2V617F from polycythemia vera. Red cell value frequencies were plotted determining if overlap existed. Chromium-51 red cell mass separated polycythemia vera from essential thrombocythemia JAK2V617F, but red cell values overlapped in 25.0-54.7%. Our data indicate that a significant proportion of polycythemia vera patients may be underdiagnosed by using only red cell values. A bone marrow biopsy was performed in 199/410 (48.5%) and a serum erythropoietin value was measured in 225/410 (54.9%) of potential polycythemia vera patients at our institution. Without isotope studies, marrow biopsies and serum erythropoietin values should improve diagnostic accuracy and become mandatory, but clinical data suggests these tests have not been routinely performed. Therefore, the clinical hematologist must be aware of imperfect accuracy when using only red cell values for distinguishing essential thrombocythemia JAK2V617F from polycythemia vera. .
- Improvement of in vitro potency assays by a resting step for clinical-grade chimeric antigen receptor engineered T cells. [Journal Article]
- CCytotherapy 2019; 21(5):566-578
- CONCLUSIONS: Cryopreservation is a challenge for the functional activity of CAR-T cells. However, CAR-T cells regain their potency by overnight incubation at 37°C, which mimics the clinical application setting. Therefore, an overnight resting step should be included in in vitro potency assays.
- Manganese-52 production cross-section measurements via irradiation of natural chromium targets up to 20 MeV. [Journal Article]
- ARAppl Radiat Isot 2019; 147:165-170
- Manganese-52g, 54 and Chromium-51 production cross-section measurements were conducted using natural chromium foils and copper monitor foils. Proton beam energies between 10 and 20 MeV were used for …
Manganese-52g, 54 and Chromium-51 production cross-section measurements were conducted using natural chromium foils and copper monitor foils. Proton beam energies between 10 and 20 MeV were used for target bombardment. After bombardment, the irradiated foils were allowed to decay for at least 48 h and radioactivity was quantified using a high-purity germanium detector. The maximum 52gMn cross-section was 90.8 ± 16.0 mb at 14.3 ± 0.8 MeV. These data contribute to the existing nuclear data for cyclotron production of 52gMn at low to medium proton energies.
- Measuring natural killer cell cytotoxicity by flow cytometry. [Journal Article]
- PPathology 2019; 51(3):286-291
- Natural killer (NK) cell cytotoxic function is critical in guarding an organism against viral infections and malignantly transformed cells. Although the 51Chromium (51Cr)-release assay is regarded as…
Natural killer (NK) cell cytotoxic function is critical in guarding an organism against viral infections and malignantly transformed cells. Although the 51Chromium (51Cr)-release assay is regarded as the gold standard for assessing NK cell cytolytic activity, this method is associated with a number of technical problems including the use of radioactive reagents and inconsistent assay performance, due to the lack of assay standardisation across laboratories. Here we describe the setup of a flow cytometry (FC) based method for the measurement of NK cell cytotoxicity, suitable for patient testing. The FC protocol was assessed using four normal samples, and reference values for NK activity of the local Hong Kong population were defined by 40 peripheral blood samples from healthy volunteers. For method validation, we tested a total of 13 specimens including nine healthy individuals and four patients with clinical conditions that were expected to have NK cell dysfunction. We directly compared those results between FC and the 51Cr-release assay and we were able to demonstrate that FC is a clinically valid method for measuring NK cell function in a clinical setting.
- Intestinal permeability after Mediterranean diet and low-fat diet in non-alcoholic fatty liver disease. [Clinical Trial]
- WJWorld J Gastroenterol 2019 Jan 28; 25(4):509-520
- CONCLUSIONS: Mediterranean diet is an effective strategy for treating overweight, visceral obesity and serum transaminase in patients with NAFLD. If the Mediterranean diet can improve intestinal permeability in patients with NAFLD, it deserves further investigation.
- Evaluating Antibody-Dependent Cell-Mediated Cytotoxicity by Chromium Release Assay. [Journal Article]
- MMMethods Mol Biol 2019; 1913:167-179
- Antibody-dependent cell-mediated cytotoxicity (ADCC) is a mechanism in which immune cell activation is induced by the cross-linking of CD16 with the Fc region of antibodies that at the same time bind…
Antibody-dependent cell-mediated cytotoxicity (ADCC) is a mechanism in which immune cell activation is induced by the cross-linking of CD16 with the Fc region of antibodies that at the same time bind specifically to cell surface antigens. ADCC stimulates the secretion of perforin, granzymes, and cytokines leading to lysis of the malignant cells. Natural killer (NK) cells express the CD16 receptor and can therefore be activated by ADCC to kill tumor cells. To study the cytotoxicity of NK cells against cancer cells, an ADCC-based assay is described: the chromium release assay. In this method, the antibody trastuzumab, which binds specifically to HER2-positive malignant cells, is used to trigger ADCC.
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- Measurement and Quantitative Characterization of Whole-Body Pharmacokinetics of Exogenously Administered T Cells in Mice. [Journal Article]
- JPJ Pharmacol Exp Ther 2019; 368(3):503-513
- Here we have investigated whole-body pharmacokinetics (PK) of exogenously administered T cells in a mouse model of melanoma and have developed a physiologically based pharmacokinetic (PBPK) model to …
Here we have investigated whole-body pharmacokinetics (PK) of exogenously administered T cells in a mouse model of melanoma and have developed a physiologically based pharmacokinetic (PBPK) model to quantitatively characterize the data. T cells were isolated from the spleen of tumor-bearing mice, activated, and labeled with chromium-51 to facilitate the quantification. Labeled T cells were injected in the tumor-bearing mice, and PK was measured in 19 different tissues. It was found that T cells disappear from the blood rapidly after administration and accumulate in the tissues to various extents. Spleen, liver, lung, kidney, bone, and lymph nodes accounted for more than 90% of T cells in the body. The distribution of T cells in solid tumors was found to be very low, hovering below 1%ID/g (percent of injected dose per gram of tissue) during the entire study. However, this observation may differ for targeted TCR-T and CAR-T cells. Observed PK profiles also suggest that T-cell-based therapies may be more successful in treating cancers of the lymphatic system and bone marrow metastases compared to solid tumors. A PBPK model was developed to characterize the whole-body PK of T cells, which incorporated key processes such as extravasation, elimination, and recirculation of T cells via lymph flow. Retention factors were incorporated into the spleen, liver, and kidney compartment to adequately capture the PK profiles. The model was able to characterize observed PK profiles reasonably well, and parameters were estimated with good confidence. The PK data and PBPK model presented here provide unprecedented insight into the biodistribution of exogenously administered T cells.