Toxicologic Pathology最新文献

Recommendations and practical considerations for sample collection, fixation, preparation and imaging of peripheral nerves and ganglia for resin embedding, light microscopic evaluation and transmission electron microscopy for ultrastructural pathology evaluation, based on the experience of the authors. Uses and limitations of transmission election microscopy in nonclinical safety studies is demonstrated through case studies of control and test article-dosed nonclinical material to highlight common artifacts and findings in this increasingly important tissue for emerging pharmaceutical modalities.

The high metabolic demand and complex blood supply of the central nervous system (CNS) render it susceptible to both global and focal ischemic insults, which represent a leading cause of morbidity and mortality in humans. The effects of ischemia in the CNS are determined by duration, severity, and neuroanatomical location of the insult. The pathophysiology of ischemic cell death represents a dynamic process in which necrosis, apoptosis, and other forms of regulated cell death (i.e., necroptosis, pyroptosis, ferroptosis, and autophagic cell death) can be involved. Multiple molecular signaling pathways are implicated in ischemic cell death associated with ATP depletion, excitotoxicity, calcium overload, oxidative stress, mitochondrial dysfunction, and rough endoplasmic reticulum dysfunction. Multiple animal models have been developed to advance knowledge in the field, though translational gaps remain. Therapeutic approaches focus on timely reperfusion and emerging cytoprotective strategies. Toxicologic pathologists play a pivotal role in expanding translational research and supporting the development of emerging therapies.

Male Wistar Crl: WI(Han) rats received 40 mg methyl methanesulfonate (MMS)/kg body weight (5 mL/kg) for five consecutive days. After a three-week recovery period, all animals were terminated, and sperm was collected from vasa deferentia (adjacent to cauda epididymidis) and cauda epididymidis. Sperm was analyzed for vital parameters and by light microscopy. Samples were also collected for laser scanning microscope (LSM) evaluation. Findings comprised changes in cytoplasmic droplets (reduced number, misplacement), sperm head abnormalities (pyknosis, misshapen, elongated, stretched, thickened or thinned), curvature abnormalities (kinked, coiling, one double-headed sperm), sperm tail abnormalities (coiling, spiral winding, fusion of outer layers of tails between two sperm cells), sperm tail core (axoneme and dense fibers) abnormalities (doubling and branched structures), and outer layer of tail abnormalities (partial or complete loss, formation of bulging structures). Findings induced by the genotoxic substance MMS generally confirmed those published previously. LSM can help visualize morphological details as counterparts of the genotoxic and cytotoxic effects of MMS. LSM permits high magnifications, rapid analysis of large numbers of sperm, precise morphological details, and fewer diagnostic artifacts, consequently preventing some missed or misdiagnoses, and making it superior to classical light microscopy for morphological sperm analysis.

The nomenclature for the female reproductive system was originally published in 2014. After 10 years of practical use, the scientific community requested from the organ working group (OWG) a review of the terminology and criteria for diagnosing ovarian sex cord/stromal lesions. As a result, OWG proposes the use of "sex cord/stromal" as the base terminology for hyperplasia and tumors to better reflect their origin from the sex cord/stroma and make the terminology internally consistent. When no predominant cell type is present, these lesions should then be designated as mixed cell type (e.g., "hyperplasia, sex cord/stromal, mixed," or "tumor, sex cord/stromal, mixed, benign"). When a clear, predominate cell type is present, the diagnosis should indicate that cell type (e.g., "sex cord/stromal, granulosa cell" or "sex cord/stromal, theca cell"). In the case of tumors, benign or malignant would be applied as appropriate. With these diagnostic revisions, the OWG for the female reproductive system attempts to provide clarification and refinement of criteria to be used for sex cord/stromal lesions.

Male reproductive organs are rarely examined microscopically in developmental and reproductive toxicity (DART) studies. Therefore, few background histopathological data exist for breeding animals. Yet, toxicologic pathologists must be able to recognize spontaneous lesions in a particular organ or tissue so that these changes are not incorrectly attributed to the test item. Inflammation of the secondary sex organs is described as a common background finding in laboratory rats and mice. Breeding activity may increase the risk of infection of the male accessory glands. In the present communication, we report microscopic changes in seminal vesicles observed in Control rats mated to Control females from three fertility and early embryonic development (FEED) studies. Acute inflammation, inflammatory cell infiltrate, hypertrophy, and increased apoptosis of the glandular epithelium were frequent findings.

A 28-year-old, female Rhesus macaque (Macaca mulatta) was lethargic and inappetent despite supportive treatment. Euthanasia was elected. Necropsy revealed numerous nodules in the liver and lung. Microscopically, the liver and lung were multifocally effaced by a poorly demarcated proliferation of neoplastic epithelial cells arranged in irregular and tortuous tubules and nests. Neoplastic cells showed positive immunolabeling for CK7 and negative immunolabeling for Hep-Par1. Findings in the liver and lung were consistent with cholangiocarcinoma, which is a rare neoplasm in non-human primates and has not been previously reported as a spontaneous finding in laboratory-kept Rhesus macaques. Rhesus macaques exhibit increased tumor incidence with age similar to humans, emphasizing the need for a comprehensive understanding of spontaneous neoplasia in this species.

Thrombotic complications including myocardial infarction, stroke, venous thrombosis and pulmonary thromboembolism are common causes of drug attrition often discovered at late stages of drug development. Current nonclinical safety assessments include screening tests that detect hemorrhagic complications but do not identify conditions signaling a risk of thrombosis. Our study aimed to identify sensitive tests for detecting prothrombotic imbalance, without overt thrombosis, for use in early nonclinical drug safety assessments in rodents. Sprague Dawley rats were administered different doses of thromboplastin or tranexamic acid to induce variable intensity hypercoagulable or hypofibrinolytic states, respectively. A panel of functional and quantitative assays measuring hemostatic proteins and pathways were evaluated, in concert with traditional coagulation screening tests and blood cell counts. Profound changes were observed with different patterns of test abnormalities for the different stimuli. Measurements of D-dimer and thrombin antithrombin complex concentrations, plasminogen activator inhibitor-1 and Factor VIIa activity were among the most sensitive tests of hypercoagulability. In contrast, hypofibrinolysis was best characterized in a kinetic, turbidimetric assay. Traditional coagulation screening tests were relatively insensitive, and no single test defined the cause of prothrombotic imbalance. Our results demonstrate that customized biomarker panels can detect early drug-induced prothrombotic states in rats arising from distinct mechanisms.

Conscious telemetry-instrumented dogs are used during cardiovascular safety assessment in early drug development for the collection of cardiovascular function parameters such as electrocardiography (ECG), heart rate, mean arterial pressure, and cardiac contractility. To refine the use of animals for exploratory toxicology studies, these dogs may be repurposed into these studies following failure of their implanted device. Telemetry instrumentation involves surgical placement of a pressure catheter through the left ventricular apex of the heart. Slight variations in placement and extension of the catheter tip into the ventricular chamber lead to variability in cardiac pathology associated with the instrumentation. Reuse of these animals in toxicologic assessments therefore requires the pathologist to be aware of the spectrum of histologic changes that may occur because of telemetry instrumentation. This report describes cardiac findings in 12 telemetry-instrumented male dogs with implant duration ranging from 7 to 37 months and discusses considerations and recommendations for use of these animals.

Digital pathology (DP) for the purpose of primary reads has emerged as a transformative tool in the practice of histopathology and has already proved to be suitable, bringing numerous advantages over traditional light microscopy (LM). This position paper promotes the adoption of DP, particularly whole slide imaging (WSI), within toxicologic pathology, emphasizing its applicability in Good Laboratory Practice (GLP)-compliant nonclinical safety assessments. With established benefits such as efficiency, remote collaboration, data security, and compatibility with artificial intelligence AI-based tools, DP represents a reliable and advanced alternative. This paper offers a counterpoint to recent skepticism expressed in the literature on the readiness of DP including discussion of implementation strategies, technical requirements, and the growing body of validation evidence supporting DP's utility in toxicologic pathology.

The molecular identification of alpha2 urinary protein in male rat kidneys is crucial in distinguishing human relevant from rat-specific cases of nephropathy caused by protein accumulation. As protein accumulation in the kidney presents uniformly as hyaline eosinophilic droplets, the identification of the causative protein can be very difficult, especially if suitable antibodies are lacking. We describe the successful identification of two morphologically similar protein accumulations (alpha2u protein and lysozyme) in rat kidneys by the matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MSI). The potential benefits of MSI may extend to other areas of toxicologic pathology, including instances where the protein accumulation must be characterized and the initial steps are unclear or the composition is unknown.