Non-invasive capnodynamic mixed venous oxygen saturation during major changes in oxygen delivery.

Mixed venous oxygen saturation (SvO2) is an important variable in anesthesia and intensive care but currently requires pulmonary artery catheterization. Recently, non-invasive determination of SvO2 (Capno-SvO2) using capnodynamics has shown good agreement against CO-oximetry in an animal model of modest hemodynamic changes. The purpose of the current study was to validate Capno-SvO2 against CO-oximetry during major alterations in oxygen delivery. Furthermore, evaluating fiberoptic SvO2 for its response to the same challenges. Eleven mechanically ventilated pigs were exposed to oxygen delivery changes: increased inhaled oxygen concentration, hemorrhage, crystalloid and blood transfusion, preload reduction and dobutamine infusion. Capno-SvO2 and fiberoptic SvO2 recordings were made in parallel with CO-oximetry. Respiratory quotient, needed for capnodynamic SvO2, was measured by analysis of mixed expired gases. Agreement of absolute values between CO-oximetry and Capno-SvO2 and fiberoptic SvO2 respectively, was assessed using Bland-Altman plots. Ability of Capno- SvO2 and fiberoptic SvO2 to detect change compared to CO-oximetry was assessed using concordance analysis. The interventions caused significant hemodynamic variations. Bias between Capno-SvO2 and CO-oximetry was + 3% points (95% limits of agreements - 7 to + 13). Bias between fiberoptic SvO2 and CO-oximetry was + 1% point, (95% limits of agreements - 7 to + 9). Concordance rate for Capno-SvO2 and fiberoptic SvO2 vs. CO-oximetry was 98% and 93%, respectively. Capno-SvO2 generates absolute values close to CO-oximetry. The performance of Capno-SvO2 vs. CO-oximetry was comparable to the performance of fiberoptic SvO2 vs. CO-oximetry. Capno-SvO2 appears to be a promising tool for non-invasive SvO2 monitoring.

Hemodynamic evaluation of anesthetized baboons and piglets by transpulmonary thermodilution: Normal values and interspecies differences with respect to xenotransplantation.

BACKGROUND: Transpulmonary thermodilution is well established as a tool for in-depth hemodynamic monitoring of critically ill patients during surgical procedures and intensive care. It permits easy assessment of graft function following cardiac transplantation and guides post-operative volume and catecholamine therapy. Since no pulmonary catheter is needed, transpulmonary thermodilution could be useful in experimental cardiac pig-to-baboon xenotransplantation. However, normal values for healthy animals have not yet been reported. Here, we present data from piglets and baboons before xenotransplantation experiments and highlight differences between the two species and human reference values. METHODS: Transpulmonary thermodilution from baboons (body weight 10-34 kg) and piglets (body weight 10-38kg) were analyzed. Measurements were taken in steady state after induction of general anesthesia before surgical procedures commenced. Cardiac index (CI), mean arterial pressure (MAP), systemic vascular resistance index (SVRI), parameters quantifying cardiac filling (global end-diastolic volume index, GEDI), and pulmonary edema (extravascular lung water, ELWI) were assessed. RESULTS: Preload, afterload, and contractility parameters clearly correlated with total body weight or body surface area. Baboons had lower CI values than weight-matched piglets (4.2 ± 0.9l/min/m2 vs 5.3 ± 1.0/min/m2 , P < .01). MAP and SVRI were higher in baboons than piglets (MAP: 99 ± 22 mm Hg vs 62 ± 11 mm Hg, P < .01; SVRI: 1823 ± 581 dyn*s/cm5 *m2 vs 827 ± 204 dyn*s/cm5 *m2 , P < .01). GEDI and ELWI did differ significantly between both species, but measurements were within similar ranges (GEDI: 523 ± 103 mL/m2 vs 433 ± 78 mL/m2 , P < .01; ELWI: 10 ± 3 mL/kg vs 11 ± 2 mL/kg, P < .01). Regarding adult human reference values, CI was similar to both baboons and piglets, but all other parameters were different. CONCLUSIONS: Parameters of preload, afterload, and contractility differ between baboons and piglets. In particular, baboons have a much higher afterload than piglets, which might be instrumental in causing perioperative xenograft dysfunction and post-operative myocardial hypertrophy after orthotopic pig-to-baboon cardiac xenotransplantation. Most transpulmonary thermodilution-derived parameters obtained from healthy piglets and baboons lie outside the reference ranges for humans, so human normal values should not be used to guide treatment in those animals. Our data provide reference values as a basis for developing algorithms for perioperative hemodynamic management in pig-to-baboon cardiac xenotransplantation.

A non-clinical comparative study of IL-23 antibodies in psoriasis.

Four antibodies that inhibit interleukin (IL)-23 are approved for the treatment of moderate-to-severe plaque psoriasis. Here, we present non-clinical data comparing ustekinumab, guselkumab, tildrakizumab and risankizumab with regard to thermostability, IL-23 binding affinity, inhibitory-binding mode, in vitro potency and in vivo efficacy. Risankizumab and guselkumab exhibited 5-fold higher affinity for IL-23 and showed more potent inhibition of IL-23 signaling than ustekinumab and tildrakizumab. Risankizumab and guselkumab completely blocked the binding of IL-23 to IL-23Rα as expected, whereas tildrakizumab did not. In vitro, risankizumab and guselkumab blocked the terminal differentiation of TH17 cells in a similar manner, while tildrakizumab had minimal impact on TH17 differentiation. In a human IL-23-induced ear-swelling mouse model, risankizumab and guselkumab were more effective than ustekinumab and tildrakizumab at reducing IL-17, IL-22, and keratinocyte gene expression. Our results indicate that the four clinically approved antibodies targeting IL-23 differ in affinity and binding epitope. These attributes contribute to differences in in vitro potency, receptor interaction inhibition mode and in vivo efficacy in preclinical studies as described in this report, and similarly may affect the clinical performance of these drugs.

The BTG/TOB family protein TIS21 regulates stage-specific proliferation of developing thymocytes.

As thymocytes undergo differentiation in the thymus, they progress through distinct phases of quiescence and proliferation. Identifying cellular mechanisms that maintain thymocytes in a non-dividing state is critical to fully understand T cell development. A member of the B cell translocation gene/transducer of ErbB-2 (BTG/TOB) family of anti-proliferative proteins was identified as a key mediator of the quiescent state in peripheral anergic and unstimulated T cells. Here, we demonstrate that the BTG/TOB family member TPA-inducible sequence 21 (TIS21) is expressed in quiescent CD44+ CD25- early progenitor thymocytes and CD44- CD25+ cells prior to TCR beta-selection. However, TIS21 expression is decreased in proliferating CD25+ CD44+ progenitor thymocytes and CD25(low) CD44- beta-selected cells, suggesting that its regulated expression may enable thymocytes to remain quiescent in the absence of mitogenic signals. We addressed the role of TIS21 in regulating thymocyte stage-specific expansion by ectopically expressing TIS21 in developing thymocytes and hematopoietic progenitors. Dysregulated expression of TIS21 inhibited the expansion of thymocytes even in the presence of endogenous mitogenic signals, while thymocyte differentiation was unimpeded. These findings imply that the intracellular mechanisms regulating thymocyte differentiation and proliferation, which are induced downstream of developmental cues, function independently during early T cell development.

High frequency of leukemic clones in newborn screening blood samples of children with B-precursor acute lymphoblastic leukemia.

The detection of leukemia cells on newborn genetic screening cards ("Guthrie cards") of a small group of patients and several sets of identical twins developing acute lymphoblastic leukemia (ALL) with identical phenotypic and chromosomal markers has provided evidence that childhood ALL cases may arise in utero. We conducted a retrospective study of a randomly selected group of childhood B-precursor ALL patients to determine the frequency of the presence of "leukemic" clones prenatally in ALL cases by testing newborn screening cards. The 17 ALL patients analyzed had a median age of 46 months (range, 18 months to 13 years) and had median presenting white blood cell (WBC) counts of 10 950/microL (range, 2900-70 300/microL) at diagnosis. A clonal rearrangement of the immunoglobulin heavy chain (IgH) gene was identified in diagnostic lymphoblasts and sequenced and patient-specific primers were used to amplify DNA from blood samples on the patient's newborn screening cards. Twelve of the 17 (71%) analyzed newborn cards had detectable IgH rearrangements amplified by seminested polymerase chain reaction. DNA sequencing confirmed that the IgH rearrangements detected matched the IgH sequences identified from diagnostic leukemia cells, indicating the presence of a "leukemic" clone at birth. There were no differences in age or presenting WBC counts between the cases with or without positive newborn screening cards. All 6 patients with hyperdiploid ALL had detectable "leukemic" clones on their cards. The results of our study support the notion that a high proportion of childhood B-precursor ALL cases arise in utero, although postnatal events are also important factors in leukemogenesis.