Toxicology Paradise: Sorting Out Adverse and Non-adverse Findings in Animal Toxicity Studies.

A challenge for all toxicologists is defining what study findings are actually adverse versus non-adverse in animal toxicity studies, and which ones are relevant for generating a no observed adverse effect level (NOAEL) to assess human risk. This article presents views on this challenge presented by toxicologists, toxicologic pathologists, and regulatory reviewers at the 2019 annual meeting of the American College of Toxicology during a workshop entitled "Toxicology Paradise: Sorting Out Adverse and Non-adverse Findings." The speakers noted that setting a NOAEL is not always straightforward, not only for small molecules but also for biopharmaceuticals, and that a "weight of evidence" approach often is more useful than a rigid threshold-setting algorithm.

Spinal epidural hematoma following a thoracic epidural in a child with sickle cell disease.

Acute liver dysfunction in the perioperative period may increase the risk of epidural hematoma in a patient with a neuraxial catheter. Coagulation testing needs to be carefully monitored in these patients. An epidural hematoma should be ruled out urgently by CT or MRI in cases of a persistent motor block.

Increased prevalence of potential right-to-left shunting in children with sickle cell anaemia and stroke.

'Paradoxical' embolization via intracardiac or intrapulmonary right-to-left shunts (RLS) is an established cause of stroke. Hypercoagulable states and increased right heart pressure, which both occur in sickle cell anaemia (SCA), predispose to paradoxical embolization. We hypothesized that children with SCA and overt stroke (SCA + stroke) have an increased prevalence of potential RLS.

Stress reticulocytes lose transferrin receptors by an extrinsic process involving spleen and macrophages.

As they mature into erythrocytes during normal erythropoiesis, reticulocytes lose surface transferrin receptors before or concurrently with reticulin. Exosome release accounts for most of the loss of transferrin receptors from reticulocytes. During erythropoietic stress, reticulocytes are released early from hematopoietic tissues and have increased reticulin staining and transferrin receptors.

Hydroxycarbamide versus chronic transfusion for maintenance of transcranial doppler flow velocities in children with sickle cell anaemia-TCD With Transfusions Changing to Hydroxyurea (TWiTCH): a multicentre, open-label, phase 3, non-inferiority trial.

Background: For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions.

Methods: TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada.

Controlled trial of transfusions for silent cerebral infarcts in sickle cell anemia.

Background: Silent cerebral infarcts are the most common neurologic injury in children with sickle cell anemia and are associated with the recurrence of an infarct (stroke or silent cerebral infarct). We tested the hypothesis that the incidence of the recurrence of an infarct would be lower among children who underwent regular blood-transfusion therapy than among those who received standard care.

Methods: In this randomized, single-blind clinical trial, we randomly assigned children with sickle cell anemia to receive regular blood transfusions (transfusion group) or standard care (observation group).

Predictors of health-related quality of life over time among adolescents and young adults with sickle cell disease.

Little is known about what factors affect the health-related quality of life (HRQoL) of adolescents and young adults (AYAs) with sickle cell disease (SCD), and how their HRQoL changes over time. This retrospective study included 87 AYAs attending a SCD Adolescent Clinic who completed a measure of HRQoL at each visit over the course of approximately 1.3 years.

Silent cerebral infarction, income, and grade retention among students with sickle cell anemia.

Children with sickle cell anemia have a higher-than-expected prevalence of poor educational attainment. We test two key hypotheses about educational attainment among students with sickle cell anemia, as measured by grade retention and use of special education services: (1) lower household per capita income is associated with lower educational attainment; (2) the presence of a silent cerebral infarct is associated with lower educational attainment. We conducted a multicenter, cross-sectional study of cases from 22 U.

Outcomes of matched sibling donor hematopoietic stem cell transplantation for severe sickle cell disease with myeloablative conditioning and intermediate-dose of rabbit anti-thymocyte globulin.

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative therapy for sickle cell disease (SCD) in children. Despite excellent outcomes of matched sibling donor (MSD) HSCT, there is still 5-10% chance of rejection and transplant related mortality (TRM) with 12-23% incidence of graft versus host disease (GVHD). We postulated that an intermediate dose of rabbit anti-thymocyte globulin (r-ATG, 10 mg/kg cumulative) would be effective in preventing both rejection and GVHD.

Abdominal pain in children with sickle cell disease.

The differential diagnosis of abdominal pain is broad in any child, and further complicated in children with sickle cell disease (SCD). Acute causes of abdominal pain may require emergent surgery, such as for appendicitis or obstruction caused by a bezoar. Rapid intervention is necessary and life-saving in children with SCD and acute splenic or hepatic sequestration.

How to approach chronic anemia.

We present herein an approach to diagnosing the cause of chronic anemia based on a patient's history and complete blood cell count (CBC). Four patterns that are encountered frequently in CBCs associated with chronic anemias are considered: (1) anemia with abnormal platelet and/or leukocyte counts, (2) anemia with increased reticulocyte counts, (3) life-long history of chronic anemia, and (4) anemia with inappropriately low reticulocytes. The pathophysiologic bases for some chronic anemias with low reticulocyte production are reviewed in terms of the bone marrow (BM) events that reduce normal rates of erythropoiesis.

Assessing a theoretical risk of dolutegravir-induced developmental immunotoxicity in juvenile rats.

HIV-1 integrase inhibitors (INIs) are a promising class of antiretrovirals for the treatment of HIV in adults; there is interest in expanding their use into pediatric populations. A theoretical concern for developmental immunotoxicity was raised after a publication suggested that two HIV INI tool compounds inhibited in vitro cleavage activity of recombination activating genes 1 and 2 (RAG1/2) through the inhibition of their binding to recombination signal sequences. RAG1/2 are required for the development of mature B and T lymphocyte populations.

Associated risk factors for silent cerebral infarcts in sickle cell anemia: low baseline hemoglobin, sex, and relative high systolic blood pressure.

The most common form of neurologic injury in sickle cell anemia (SCA) is silent cerebral infarction (SCI). In the Silent Cerebral Infarct Multi-Center Clinical Trial, we sought to identify risk factors associated with SCI. In this cross-sectional study, we evaluated the clinical history and baseline laboratory values and performed magnetic resonance imaging of the brain in participants with SCA (HbSS or HbSβ° thalassemia) between the ages of 5 and 15 years with no history of overt stroke or seizures.

Young adults with SCD in US children's hospitals: are they different from adolescents?

Background: The period of transition from pediatric to adult care is a vulnerable time for patients with sickle cell disease (SCD). The optimal time for transition is unknown and there is no standard of care regarding this timing in the United States.

Procedures: We collected administrative data from the Pediatric Health Information System for all SCD admissions from 2000 to 2009.

Caregivers' perspectives on barriers to transcranial Doppler screening in children with sickle-cell disease.

Background: Current guidelines recommend that children with HbSS or HbSβ°thal undergo yearly transcranial Doppler screenings (TCD) to identify those at high risk for stroke. Compliance is low with yearly TCD screenings. Our objective was to describe caregiver experiences and knowledge of TCD screenings as well as barriers that may prevent screening.

Sickle cell trait, hemoglobin C trait, and invasive pneumococcal disease.

Background: The cause of historically higher rates of invasive pneumococcal disease among blacks than whites has remained unknown. We tested the hypothesis that sickle cell trait or hemoglobin C trait is an independent risk factor for invasive pneumococcal disease.

Method: Eligible children were born in Tennessee (1996-2003), had a newborn screen, enrolled in TennCare aged <1 year, and resided in a Tennessee county with laboratory-confirmed, pneumococcal surveillance.

Toxicity and toxicokinetics of metformin in rats.

Metformin is a first-line drug for the treatment of type 2 diabetes (T2D) and is often prescribed in combination with other drugs to control a patient's blood glucose level and achieve their HbA1c goal. New treatment options for T2D will likely include fixed dose combinations with metformin, which may require preclinical combination toxicology studies. To date, there are few published reports evaluating the toxicity of metformin alone to aid in the design of these studies.

Growth patterns in children with sickle cell anemia during puberty.

Background: Previous studies of children with homozygous sickle cell anemia (SCA) show impaired growth and maturation. The correlation of this suboptimal growth with metabolic and hematological factors during puberty is poorly understood.

Procedure: We studied a group of pre-adolescent children with SCA (19 males, 14 females) and healthy controls (16 males, 15 females) matched for race, sex, body size, and pubertal development.

Adherence to macrophages in erythroblastic islands enhances erythroblast proliferation and increases erythrocyte production by a different mechanism than erythropoietin.

Erythroblasts adhere to central macrophages forming erythroblastic islands in hematopoietic tissues, but the function of these islands is not understood. Murine erythroblastic islands were reconstituted in vitro with macrophages and developmentally synchronous proerythroblasts. Erythroblasts cocultured with macrophages proliferated 3-fold greater than erythroblasts cultured alone.

The anticancer activity of the transcription inhibitor terameprocol (meso-tetra-O-methyl nordihydroguaiaretic acid) formulated for systemic administration.

Terameprocol (meso-tetra-O-methyl nordihydroguaiaretic acid, formerly known as EM-1421 and M4N) is a semi-synthetic small molecule with antitumor activity occurring via selective targeting of Sp1-regulated proteins, including survivin and cdc2 that control cell cycle and apoptosis. Terameprocol is in clinical development as a site-specific transcription inhibitor in solid refractory tumors. The present studies were designed to investigate the in-vitro and in-vivo anticancer activity of terameprocol in a novel hydroxypropyl beta-cyclodextrin and polyethylene glycol solvent formulation (designated CPE) designed for safe parenteral administration.

Utility of FDG-PET/CT in follow-up of children treated for Hodgkin and non-Hodgkin lymphoma.

Positron emission tomography using F-flurodeoxyglucose (FDG-PET) is considered an excellent tool for staging and monitoring disease status in adults with lymphoma. We retrospectively reviewed results of PET/CT and diagnostic computed tomography (CT) scans performed during follow-up after completion of therapy in 41 children <18 years of age with Hodgkin lymphoma and non-Hodgkin lymphoma. PET/CT scan with uptake greater than that of the liver was considered positive.

The identification of a recurrent phosphoglycerate kinase mutation associated with chronic haemolytic anaemia and neurological dysfunction in a family from USA.

Phosphoglycerate kinase (PGK) deficiency is a rare X-linked disease that is characterised by mild to severe haemolytic anaemia, rhabdomyolysis, and variable defects in the central nervous system. In a white American family, two sons presented with haemolytic anaemia, seizures, and developmental delay. The diagnosis of PGK deficiency was made based on the remarkably low (<5% of normal) erythrocyte PGK enzyme activity level and the identification of a missense (c.