Adverse effects of polymyxin B administration to healthy horses

Background: Polymyxin B (PolyB) is used to treat endotoxemia in horses; neurologic and nephrogenic adverse effects occur in humans. Objectives: To describe PolyB adverse effects in horses. Animals: Five healthy horses (ataxia 0/5), 1 horse with cervical osteoarthritis (ataxia 1/5). Methods: Prospective blinded randomized cross-over trial; 3-weeks wash out. Horses received PolyB (PolyB 6000 IU/kg IV, 7 doses q12h, n = 6) and PolyB/gentamicin (PolyB 6000 IU/kg IV, q12h 7 doses; gentamicin 10 mg/kg IV q24h 4 doses n = 4, or q12-24 h 5 doses because of an additional erroneous dose, n = 2). Daily neurological examinations were video recorded, and ataxia graded by 3 observers. Urine status, urinary GGT/creatinine ratio, plasma creatinine, and urea were assessed every other day, EMG daily. Mixed model analysis was used to evaluate factors associated with ataxia grade and [PolyB]. Results: Median ataxia score increased from 0/5 (range 0-2/5) to 2/5 (range 1-3/5) during administration and declined to 0.5/5 (range 0-2/5) after cessation. Gentamicin co-administration (P < .01, effect size: .8), number of PolyB doses (P < .001, effect size: .6), and time since last PolyB dose (P < .001, effect size: .5) had a significant effect on ataxia grades, while horse, day, [Genta], [PolyB], and [PolyB]CSF did not. Gentamicin co-administration and [Genta] Cpeak had no effect on median [PolyB] Cpeak (4.67 and 4.89 μg/ml for PolyB and PolyB/gentamicin, respectively). Urinary GGT/creatinine ratio was elevated in 3/6 horses receiving PolyB/gentamicin. The EMG remained unchanged. Conclusions and clinical importance: PolyB caused transient ataxia, worsening with cumulative PolyB doses and gentamicin co-administration. Nephrotoxicity of PolyB was only evident when gentamicin was co-administered

Preliminary Investigation of Side Effects of Polymyxin B Administration in Hospitalized Horses

Neuro- and nephrotoxicity of polymyxins are known but clinical studies in horses are lacking. The aim of this study was to describe neurogenic and nephrogenic side effects of hospitalized horses receiving Polymyxin B (PolyB) as part of their treatment plan. Twenty horses diagnosed with surgical colic (n = 11), peritonitis (n = 5), typhlocolitis (n = 2), pneumonia, and pyometra (each n = 1) were included. Antimicrobial treatment was randomized to GENTA (gentamicin 10 mg/kg bwt q24 h IV, penicillin 30.000 IU/kg q6 h IV) or NO GENTA (marbofloxacin 2 mg/kg bwt q24 h IV, penicillin 30.000 IU/kg q6 h IV). The duration of PolyB treatment ranged from 1 to 4 days. Clinical and neurological examinations were performed, and serum PolyB concentrations were measured daily during and three days following PolyB treatment. Urinary analysis, plasma creatinine, urea and SDMA were assessed every other day. Video recordings of neurological examinations were graded by three blinded observers. All horses showed ataxia during PolyB treatment in both groups (median maximum ataxia score of 3/5, range 1–3/5). Weakness was detected in 15/20 (75%) horses. In 8/14 horses, the urinary γ-glutamyltransferase (GGT)/creatinine ratio was elevated. Plasma creatinine was mildly elevated in 1/16 horses, and SDMA in 2/10 horses. Mixed-model analysis showed a significant effect of time since last PolyB dose (p = 0.0001, proportional odds: 0.94) on the ataxia score. Ataxia and weakness should be considered as reversible adverse effects in hospitalized horses receiving PolyB. Signs of tubular damage occurred in a considerable number of horses; therefore, the nephrotoxic effect of polymyxins should be considered and urinary function monitored

Preclinical investigations using [177Lu]Lu-Ibu-DAB-PSMA toward its clinical translation for radioligand therapy of prostate cancer

[$^{177}$Lu]Lu-Ibu-DAB-PSMA was previously characterized with moderate albumin-binding properties enabling high tumor accumulation but reasonably low retention in the blood. The aim of this study was to investigate [$^{177}$Lu]Lu-Ibu-DAB-PSMA in preclinical in vivo experiments and compare its therapeutic efficacy and potential undesired side effects with those of [$^{177}$Lu]Lu-PSMA-617 and the previously developed [$^{177}$Lu]Lu-PSMA-ALB-56. BALB/c nude mice without tumors were investigated on Day 10 and 28 after injection of 10 MBq radioligand. It was revealed that most plasma parameters were in the same range for all groups of mice and histopathological examinations of healthy tissue did not show any alternations in treated mice as compared to untreated controls. Based on these results, a therapy study over twelve weeks was conducted with PC-3 PIP tumor-bearing mice for comparison of the radioligands’s therapeutic efficacy up to an activity of 10 MBq (1 nmol) per mouse. In agreement with the increased mean absorbed tumor dose, [$^{177}$Lu]Lu-Ibu-DAB-PSMA (~ 6.6 Gy/MBq) was more effective to inhibit tumor growth than [$^{177}$Lu]Lu-PSMA-617 (~ 4.5 Gy/MBq) and only moderately less potent than [$^{177}$Lu]Lu-PSMA-ALB-56 (~ 8.1 Gy/MBq). As a result, the survival of mice treated with 2 MBq of an albumin-binding radioligand was significantly increased (p < 0.05) compared to that of mice injected with [$^{177}$Lu]Lu-PSMA-617 or untreated controls. The majority of mice treated with 5 MBq or 10 MBq [$^{177}$Lu]Lu-Ibu-DAB-PSMA or [$^{177}$Lu]Lu-PSMA-ALB-56 were still alive at study end. Hemograms of immunocompetent mice injected with 30 MBq [$^{177}$Lu]Lu-Ibu-DAB-PSMA or 30 MBq [$^{177}$Lu]Lu-PSMA-617 showed values in the same range as untreated controls. This was, however, not the case for mice treated with [$^{177}$Lu]Lu-PSMA-ALB-56 which revealed a drop in lymphocytes and hemoglobin at Day 10 and Day 28 after injection. The data of this study demonstrated a significant therapeutic advantage of [$^{177}$Lu]Lu-Ibu-DAB-PSMA over [$^{177}$Lu]Lu-PSMA-617 and a more favorable safety profile as compared to that of [$^{177}$Lu]Lu-PSMA-ALB-56. Based on these results, [$^{177}$Lu]Lu-Ibu-DAB-PSMA may has the potential for a clinical translation

Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs.

Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient's coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication

Evaluation of the Effect of Storage Time on ROTEM S® Parameters in Healthy and Ill Dogs

Viscoelastic testing as a bedside test to assess global haemostasis has gained popularity in the past decade, with rotational thromboelastometry (ROTEM) and thromboelastography (TEG) being the two commonly used devices. TEG studies suggest analysis 30 min after blood sampling. However, the reproducibility of results over time for ROTEM analysis using lyophilized samples in dogs has not been established. In this study, we investigated the influence of time on viscoelastic testing, using 33 healthy staff-/client-owned dogs for blood sampling and repeated measurements of ROTEM tracings at three different time points after blood collection. Additionally, a group of 21 hospitalized patients with suspected coagulation disorders were included to investigate whether stability over time was comparable between healthy and ill dogs. We demonstrated a significant difference of ROTEM tracings over time, with a tendency towards hypocoagulability over time. These changes do have a clinical relevance as they exceed reference intervals and could therefore lead to erroneous conclusions about a patient’s coagulation status. Therefore, time-specific reference intervals are proposed and presented in this publication

Comparison of Jugular vs. Saphenous Blood Samples, Intrarater and In-Between Device Reliability of Clinically Used ROTEM S Parameters in Dogs

Rotational Thromboelastometry (ROTEM) allows for the global assessment of hemostasis in whole blood samples. Preanalytical and analytical factors may influence test results, and data about the reliability and reproducibility of lyophilized ROTEM tests are scarce. Therefore, the objective of this study was to evaluate the influence of blood collection site on ROTEM S parameters and to assess intrarater and in-between device variability. A total of thirty, healthy, staff-owned dogs were included. Blood collection and ROTEM analysis were performed by trained staff according to a standardized protocol. Extrinsically activated (tissue factor; Ex-TEM S), with the addition of cytochalasin for platelet inhibition (Fib-TEM S), and intrinsically activated (In-TEM) analyses were performed. Analysis of our data showed significant variability for various Ex-TEM S and Fib-TEM S parameters from different collection sites and intrarater and in-between device measurements. We conclude that serial monitoring with ROTEM should be performed on the same device, with blood always taken from the same collection site using a standardized blood sampling technique. While In-TEM S, apart from maximum lysis, showed very stable and reliable results, we suggest interpreting especially clotting and clot formation parameters from Ex-TEM S and Fib-TEM S tests with caution and using duplicate measurements to detect outliers and to prevent initiation of incorrect therapies

Comparison of Jugular vs. Saphenous Blood Samples, Intrarater and In-Between Device Reliability of Clinically Used ROTEM S Parameters in Dogs.

Rotational Thromboelastometry (ROTEM) allows for the global assessment of hemostasis in whole blood samples. Preanalytical and analytical factors may influence test results, and data about the reliability and reproducibility of lyophilized ROTEM tests are scarce. Therefore, the objective of this study was to evaluate the influence of blood collection site on ROTEM S parameters and to assess intrarater and in-between device variability. A total of thirty, healthy, staff-owned dogs were included. Blood collection and ROTEM analysis were performed by trained staff according to a standardized protocol. Extrinsically activated (tissue factor; Ex-TEM S), with the addition of cytochalasin for platelet inhibition (Fib-TEM S), and intrinsically activated (In-TEM) analyses were performed. Analysis of our data showed significant variability for various Ex-TEM S and Fib-TEM S parameters from different collection sites and intrarater and in-between device measurements. We conclude that serial monitoring with ROTEM should be performed on the same device, with blood always taken from the same collection site using a standardized blood sampling technique. While In-TEM S, apart from maximum lysis, showed very stable and reliable results, we suggest interpreting especially clotting and clot formation parameters from Ex-TEM S and Fib-TEM S tests with caution and using duplicate measurements to detect outliers and to prevent initiation of incorrect therapies

Methemoglobinemia, Increased Deformability and Reduced Membrane Stability of Red Blood Cells in a Cat with a CYB5R3 Splice Defect

Methemoglobinemia is an acquired or inherited condition resulting from oxidative stress or dysfunction of the NADH-cytochrome b5 reductase or associated pathways. This study describes the clinical, pathophysiological, and molecular genetic features of a cat with hereditary methemoglobinemia. Whole genome sequencing and mRNA transcript analyses were performed in affected and control cats. Co-oximetry, ektacytometry, Ellman’s assay for reduced glutathione concentrations, and CYB5R activity were assessed. A young adult European domestic shorthair cat decompensated at induction of anesthesia and was found to have persistent methemoglobinemia of 39 ± 8% (reference range A. Subsequent mRNA studies confirmed a splice defect and demonstrated expression of two mutant CYB5R3 transcripts. Erythrocytic glutathione levels were twice that of controls. Mild microcytosis, echinocytes, and multiple Ca2+-filled vesicles were found in the affected cat. Erythrocytes were unstable at high osmolarities although highly deformable as follows from the changes in elongation index and maximal-tolerated osmolarity. Clinicopathological presentation of this cat was similar to other cats with CYB5R3 deficiency. We found that methemoglobinemia is associated with an increase in red blood cell fragility and deformability, glutathione overload, and morphological alterations typical for stress erythropoiesis

Altered serum thyrotropin concentrations in dogs with primary hypoadrenocorticism before and during treatment

BACKGROUND: Thyrotropin (TSH) can be increased in humans with primary hypoadrenocorticism (HA) before glucocorticoid treatment. Increase in TSH is a typical finding of primary hypothyroidism and both diseases can occur concurrently (Schmidt's syndrome); therefore, care must be taken in assessing thyroid function in untreated human patients with HA. OBJECTIVE: Evaluate whether alterations in cTSH can be observed in dogs with HA in absence of primary hypothyroidism. ANIMALS: Thirty dogs with newly diagnosed HA, and 30 dogs in which HA was suspected but excluded based on a normal ACTH stimulation test (controls) were prospectively enrolled. METHODS: cTSH and T4 concentrations were determined in all dogs and at selected time points during treatment (prednisolone, fludrocortisone, or DOCP) in dogs with HA. RESULTS: cTSH concentrations ranged from 0.01 to 2.6 ng/mL (median 0.29) and were increased in 11/30 dogs with HA; values in controls were all within the reference interval (range: 0.01-0.2 ng/dL; median 0.06). There was no difference in T4 between dogs with increased cTSH (T4 range 1.0-2.1; median 1.3 μg/dL) compared to those with normal cTSH (T4 range 0.5-3.4, median 1.4 μg/dL; P=0.69) and controls (T4 range 0.3-3.8, median 1.8 μg/dL; P=0.35). After starting treatment, cTSH normalized after 2-4 weeks in 9 dogs and after 3 and 4 months in 2 without thyroxine supplementation. CONCLUSIONS AND CLINICAL RELEVANCE: Evaluation of thyroid function in untreated dogs with HA can lead to misdiagnosis of hypothyroidism; treatment with glucocorticoids for up to 4 months can be necessary to normalize cTSH

Iron- and erythropoietin-resistant anemia in a spontaneous breast cancer mouse model

Anemia of cancer (AoC) with its multifactorial etiology and complex pathology is a poor prognostic indicator for cancer patients. One of the main causes of AoC is cancer-associated inflammation that activates mechanisms, commonly observed in anemia of inflammation, where functional iron deficiency and iron-restricted erythropoiesis is induced by increased hepcidin levels in response to IL-6 elevation. So far only a few AoC mouse models have been described, and most of them did not fully recapitulate the interplay of anemia, increased hepcidin levels and functional iron deficiency in human patients. To test if the selection and the complexity of AoC mouse models dictates the pathology or if AoC in mice per se develops independently of iron deficiency, we characterized AoC in Trp53floxWapCre mice that spontaneously develop breast cancer. These mice developed AoC associated with high IL-6 levels and iron deficiency. However, hepcidin levels were not increased and hypoferremia coincided with anemia rather than causing it. Instead, an early shift in the commitment of common myeloid progenitors from the erythroid to the myeloid lineage resulted in increased myelopoiesis and in the excessive production of neutrophils that accumulate in necrotic tumor regions. This process could neither be prevented by iron nor erythropoietin (EPO) treatment. Trp53floxWapCre mice are the first mouse model where EPO-resistant anemia is described and may serve as a disease model to test therapeutic approaches for a subpopulation of human cancer patients with normal or corrected iron levels that do not respond to EPO