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Objective: Pulmonary blastoma is a rare, biphasic, adult-onset lung tumor. In this study, we investigate whether DICER1 pathogenic variants are a feature of pulmonary blastomas through in-depth analysis of the molecular events defining them., Methods: We performed exome-wide sequencing and DNA methylation profiling of 8 pulmonary blastomas from 6 affected persons., Results: We identified biallelic somatic DICER1 pathogenic variants in 7 of 8 cases. The remaining case had a solitary missense pathogenic variant in the RNase IIIb domain of DICER1. Six of 8 cases carried a CTNNB1 hotspot variant and 4 of 8 had a somatic pathogenic variant in TP53. Methylation analysis showed that the pulmonary blastomas clustered with other DICER1-mutated tumors and not with other more common types of lung cancer., Conclusion: We conclude somatic DICER1 pathogenic variants are the major driver of pulmonary blastoma and are likely to act in conjunction with CTNNB1 hotspot variants that are often present., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: MGE is an employee of Caris Life Sciences and owns stock in Caris Life Sciences. POF has received paid consulting services and honoraria outside of this work from Amgen, Astellas, AstraZeneca, Bristol Meyers Squibb, EMD Serono, Incyte, Merck, Novartis, Pfizer, and Precision Rx-Dx. AvD is a co-founder and shareholder of Heidelberg Epignostix GmbH and declares patents related to methods for diagnosing tumors using antibodies from Dianova and related to DNA-methylation based methods for classifying tumor species. All other authors declare no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Aims: The identification of haemophagocytosis in bone marrow (BM) is recurrently identified in patients with severe COVID-19. These initial COVID-19 autopsy studies have afforded valuable insight into the pathophysiology of this disease; however, only a limited number of case series have focused on lymphoid or haematopoietic tissues., Methods: BM and lymph node (LN) specimens were obtained from adult autopsies performed between 1 April 2020 and 1 June 2020, for which the decedent had tested positive for SARS-CoV-2. Tissue sections (H&E, CD3, CD20, CD21, CD138, CD163, MUM1, kappa/lambda light chains in situ hybridisation) were examined by two haematopathologists, who recorded morphological features in a blinded fashion. Haemophagocytic lymphohistiocytosis (HLH) was assessed based on HLH 2004 criteria., Results: The BM demonstrated a haemophagocytic pattern in 9 out of 25 patients (36%). The HLH pattern was associated with longer hospitalisation, BM plasmacytosis, LN follicular hyperplasia and lower aspartate aminotransferase (AST), as well as ferritin at demise. LN examination showed increased plasmacytoid cells in 20 of 25 patients (80%). This pattern was associated with a low absolute monocyte count at diagnosis, lower white cell count and lower absolute neutrophil count at demise, and lower ferritin and AST at demise., Conclusions: Autopsy results demonstrate distinct morphological patterns in BM, with or without haemophagocytic macrophages, and in LN, with or without increased plasmacytoid cells. Since only a minority of patients met diagnostic criteria for HLH, the observed BM haemophagocytic macrophages may be more indicative of an overall inflammatory state., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

The most common type of melanoma is cutaneous melanoma (CM). The predominant mutational signature is that of ultraviolet radiation (UVR) exposure. The Cancer Genome Atlas (TCGA) molecular classification includes four major subtypes of CM based on common genetic alterations involving the following genes: BRAF, NRAS, and NF1, with a small fraction being "triple" wild-type. The two main signaling pathway abnormalities in CM are the mitogen-activated protein kinase (MAPK) pathway and the phosphoinositol-3-kinase (PI3K) pathway. Other less common types include mucosal melanomas (MM) and uveal melanoma (UM), which have a significantly different genomic landscape. Although few studies reported rare cases with HPV-positive (HPV+) melanoma, the clinicopathological and molecular characteristic of this entity has not been well-described. Among the 2084 melanoma cases queried at our institution, we identified seven patients diagnosed with HPV+ melanoma (prevalence 0.03 %), including five instances of CM and two of MM. The majority of cases were positive for HPV16 (n = 6). Most of the patients were elderly and with advanced disease (n = 6), although this finding may be attributed to the relative frequency of our institution testing advanced-stage tumors. Histologically, most cases showed high degree of pleomorphism and high mitotic count (5 or more mitoses/mm 2 ) (n = 6). UVR signature was present in the CM, but not in the MM cases. Alterations in either MAPK and/or PI3K pathways were detected in the majority of cases (n = 6). The most common genetic abnormalities detected in this study occurred in the TERT promoter (TERTp) (n = 5), a finding that has been reported to be associated with aggressive disease. Our data shows that while HPV+ melanoma is rare, identifying this disease entity could help guide therapy given the demonstrated genomic alterations., Competing Interests: Declaration of competing interest HG, CO, AE, DAB, MJO, and MGE disclose a financial association with Caris Life Sciences (full-time employment, travel/speaking expenses, stock/stock options)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Breast implant-associated anaplastic large cell lymphoma has been recognized as a distinct entity in the World Health Organization classification of hematolymphoid neoplasms. These neoplasms are causally related to textured implants that were used worldwide until recently. Consequently, there is an increased demand for processing periprosthetic capsules, adding new challenges for surgeons, clinicians, and pathologists. In the literature, the focus has been on breast implant-associated anaplastic large cell lymphoma; however, benign complications related to the placement of breast implants occur in up to 20% to 30% of patients. Imaging studies are helpful in assessing patients with breast implants for evidence of implant rupture, changes in tissues surrounding the implants, or regional lymphadenopathy related to breast implants, but pathologic examination is often required. In this review, we couple our experience with a review of the literature to describe a range of benign lesions associated with breast implants that can be associated with different clinical presentations or pathogenesis and that may require different diagnostic approaches. We illustrate the spectrum of the most common of these benign disorders, highlighting their clinical, imaging, gross, and microscopic features. Finally, we propose a systematic approach for the diagnosis and handling of breast implant specimens in general., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Germline and somatic pathogenic variants (PVs) in DICER1 , encoding a miRNA biogenesis protein, are associated with a wide variety of highly specific pathologic entities. The lung tumors pleuropulmonary blastoma, pulmonary blastoma (PB), and well-differentiated fetal lung adenocarcinoma (WDFLAC) are all known to harbor DICER1 biallelic variants (loss of function and/or somatic hotspot missense mutations), and all share pathologic features reminiscent of the immature lung. However, the role of DICER1 PVs in non-small cell lung cancer (NSCLC) is relatively unknown. Here, we aimed to establish the spectrum of lung pathologies associated with DICER1 hotspot PVs and to compare the mutational landscape of DICER1 -mutated NSCLC with and without hotspots. We queried DNA sequencing data from 12,146 NSCLCs featuring somatic DICER1 variants. 235 (1.9%) cases harboring ≥ 1 DICER1 PV were found and 9/235 (3.8%) were DICER1 hotspot-positive cases. Histologic review of DICER1 hotspot-positive cases showed that all but one tumor were classified as within the histologic spectrum of PB/WDFLAC, whereas all the DICER1 non-hotspot double variants were classified as lung adenocarcinomas, not otherwise specified. Comparison between the mutational landscape of DICER1 hotspot-positive and hotspot-negative cases revealed a higher frequency of CTNNB1 mutations in the hotspot-positive cases (5/9 vs. 2/225; P <0.00001). We conclude that DICER1 somatic hotspots are not implicated in the most common forms of NSCLC but rather select for morphologic features of lung tumor types such as PB and WDFLAC. As a corollary, cases showing this tumor morphology should undergo testing for DICER1 variants, and if positive, genetic counseling should be considered., Competing Interests: Conflicts of Interest and Source of Funding: M.E., J.S., and M.G.E. are employees of Caris Life Sciences. P.O.F. has received paid consulting services and honoraria outside of this work from Amgen, Astellas, AstraZeneca, Bristol Meyers Squibb, EMD Serono, Incyte, Merck, Novartis, Pfizer, and Precision Rx-Dx. For the remaining authors none were declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Lymphoid aggregates are found in a minority of bone marrow biopsy and aspirate specimens, and when present, the distinction between benign and malignant aggregates can represent a diagnostic challenge. Morphologic and immunophenotypic evaluation of the aggregates can aid in that distinction but in a few cases, detection of immunoglobulin heavy chain (IGH) and kappa light chain (IGK) gene rearrangements may be needed to rule in or out a malignant disease process. We studied the role of testing for IGH/IGK rearrangements in the distinction between benign and malignant B cell-predominant lymphoid aggregates. Only a few studies have addressed this issue and most lacked an adequate number of cases for establishing statistical significance. Our study retrospectively evaluated 120 bone marrow aspirate and biopsy specimens, 79 cases originally diagnosed with benign lymphoid aggregates [4,5], and 41 demonstrating a B-cell lymphoma with malignant aggregates. Immunohistochemical stains were performed on all cases in our study and flow cytometry results were available in the vast majority of cases (98%). All patients included in our study but 9 had at least 2 years of clinical follow-up information. Of the malignant lymphoma cases, IGH/IGK rearrangements were demonstrated by polymerase chain reaction in 60% of the cases. Moreover, clonal rearrangements were identified in 15% of the cases with benign aggregates. After at least 2 years of follow-up, only one case with a positive clonality study occurring in the setting of morphologically benign-appearing bone marrow lymphoid aggregates experienced a relapse of non-Hodgkin lymphoma. Molecular analysis of the IGH and IGK genes may have utility in confirming the presence of malignancy in bone marrow aspirates and biopsy specimens. False-negative results, however, are possible due to testing limitations and sampling issues. Moreover, patients with conditions such as autoimmune disorders or infectious diseases are shown to also develop clonal B-cell lymphoid aggregates. As a result, we recommend a thorough morphological examination, informative immunohistochemical staining, accurate flow cytometric analysis, and current IGH/IGK rearrangement testing when evaluating bone marrow specimens containing B cell-predominant lymphoid aggregates, with the knowledge that molecular clonality results should be carefully interpreted in the context of morphological and immunophenotypic findings to prevent misdiagnosis., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Breast implant anaplastic large cell lymphoma (ALCL) is a T-cell neoplasm arising around textured breast implants that was recognized recently as a distinct entity by the World Health Organization. Rarely, other types of lymphoma have been reported in patients with breast implants, raising the possibility of a pathogenetic relationship between breast implants and other types of lymphoma. We report eight cases of Epstein-Barr virus (EBV)-positive large B-cell lymphoma associated with breast implants. One of these cases was invasive, and the other seven neoplasms were noninvasive and showed morphologic overlap with breast implant ALCL. All eight cases expressed B-cell markers, had a non-germinal center B-cell immunophenotype, and were EBV+ with a latency type III pattern of infection. We compared the noninvasive EBV+ large B-cell lymphoma cases with a cohort of breast implant ALCL cases matched for clinical and pathologic stage. The EBV+ large B-cell lymphoma cases more frequently showed a thicker capsule, and more often were associated with calcification and prominent lymphoid aggregates outside of the capsule. The EBV+ B-cell lymphoma cells were more often arranged within necrotic fibrinoid material in a layered pattern. We believe that this case series highlights many morphologic similarities between EBV+ large B-cell lymphoma and breast implant ALCL. The data presented suggest a pathogenetic role for breast implants (as well as EBV) in the pathogenesis of EBV+ large B-cell lymphoma. We also provide some histologic findings useful for distinguishing EBV+ large B-cell lymphoma from breast implant ALCL in this clinical setting., (© 2021. The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.)

Breast implant-associated anaplastic large cell lymphoma (ALCL) is a distinctive type of T-cell lymphoma that arises around textured-surface breast implants. In a subset of patients, this disease can involve surrounding tissues, spread to regional lymph nodes, and rarely metastasize to distant sites. The aim of this study was to assess sequential pathologic specimens from patients with breast implant-associated ALCL to better understand the natural history of early-stage disease. To achieve this goal, we searched our files for patients who had breast implant-associated ALCL and who had undergone earlier surgical intervention with assessment of biopsy or cytologic specimens. We then focused on the patient subset in whom a definitive diagnosis was not established, and patients did not receive current standard-of-care therapy at that time. We identified a study group of ten patients with breast implant-associated ALCL in whom pathologic specimens were collected 0.5 to 4 years before a definitive diagnosis was established. A comparison of these serial biopsy specimens showed persistent disease without change in pathologic stage in three patients, progression in five patients, and persistence versus progression in two patients. Eventually, six patients underwent implant removal with complete capsulectomy and four underwent partial capsulectomy. Seven patients also received chemotherapy because of invasive disease, three of whom also received radiation therapy, two brentuximab vedotin after chemotherapy failure, and one allogeneic stem cell transplant. Eight patients achieved complete remission and two had partial remission after definitive therapy. At time of last follow-up, six patients were alive without disease, one had evidence of disease, one died of disease, and two patients died of unrelated cancers. In summary, this analysis of sequential specimens from patients with breast implant-associated ALCL suggests these neoplasms persist or progress over time if not treated with standard-of-care therapy., (© 2021. The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.)

Since the first reported case in 1997, over 600 women with breast implant-associated anaplastic large cell lymphoma (BI ALCL) have been reported. BI ALCL is a CD30-positive T-cell lymphoma that carries clonal T-cell receptor gene rearrangements, and a subset of cases harbors mutations in the JAK-STAT signaling pathway. Rarely, other histologic types of lymphoma have been reported in association with breast implants, including fewer than 10 cases of B-cell origin. Here, we describe three additional patients with B-cell lymphoma occurring around breast implants. Two of these patients developed extranodal marginal zone lymphoma in the peri-implant capsule, one of which had a concurrent ALCL within the superficial lining of the capsule. The third patient presented with diffuse large B-cell lymphoma inside the breast parenchyma surrounding her implant. Determining the etiology and risk factors for the development of B-cell lymphomas associated with breast implants remains challenging, given the wide spectrum of histologic features and the rarity of these neoplasms. Ultimately, we document three new cases of B-cell lymphoma arising around breast implants and highlight their clinical and pathologic features in order to expand our understanding of this rare disease presentation., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The current literature credits Keech and Creech with the first report of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) in 1997. Here we discuss what we consider is the first ever description of BIA-ALCL, a recently recognized entity by the WHO. We unearthed the description of a patient that was diagnosed with primary effusion lymphoma (PEL), surrounding a breast implant in 1996. In light of the current state of knowledge, we evaluated the evidence presented in 1996 and consider that BIA-ALCL is a more appropriate diagnosis rather than PEL. We base our proposal on the following features: 1). clinical presentation of effusion around a breast implant, 2). occurring in an HIV negative patient, 3). absence of EBV co-infection, and 4). a historically questionable demonstration of HHV8. In effect we further support that HHV8 is not related with BIA-ALCL based on the following facts: 1). An extensive review of the literature did not disclose a similar case in the next 24 years, 2). Use of state of the art HHV8 by immunohistochemistry did not disclose any positive case among 30 randomly tested cases. We believe this matter is of importance because in the current WHO, the assertion that PEL is a possible complication of breast implants may lead to a diagnosis with poor prognosis and susceptible of morbidity related with aggressive therapy, in contrast with BIA-ALCL that can be cured with surgery alone., (Copyright © 2020. Published by Elsevier Inc.)

Breast implant anaplastic large cell lymphoma is an entity recently recognized by the World Health Organization. The tumor arises around textured-surface breast implants and is usually confined to the surrounding fibrous capsule. Currently, there are no recommendations for handling and sampling of capsules from patients with suspected breast implant anaplastic large cell lymphoma without a grossly identifiable tumor. We analyzed complete capsulectomies without distinct gross lesions from patients with breast implant anaplastic large cell lymphoma. The gross appearance of the capsules as well as the presence, extent and depth of tumor cells on the luminal side and number of sections involved by lymphoma were determined by review of routine stains and CD30 immunohistochemistry. We then used a mathematical model that included the extent of tumor cells and number of positive sections to calculate the minimum number of sections required to identify 95% of randomly distributed lesions. We identified 50 patients with breast implant anaplastic large cell lymphoma who had complete capsulectomies. The implants were textured in all 32 (100%) cases with available information. Anaplastic large cell lymphoma was found in 44/50 (88%) capsules; no tumor was found in six (12%) patients who had lymphoma cells only in the effusion. The median number of sections reviewed was 20 (range, 2-240), the median percentage of sections involved by tumor was 6% (range, 0-90%), and the median percentage of sections involved by lymphoma was 10% (range, 0-90%). Invasion deep into or through the capsule was identified in 18/50 (36%) patients. In patients with breast implant anaplastic large cell lymphoma without a grossly identifiable tumor we identified a spectrum of involvement and we propose a protocol for handling, sampling and reporting these cases. The number of sections to exclude the presence of lymphoma with more than 95% certainty was supported by a mathematic rationale.

Tanezumab, an anti-nerve growth factor (NGF) antibody, is in development for management of chronic pain. During clinical trials of anti-NGF antibodies, some patients reported unexpected adverse events requiring total joint replacements, resulting in a partial clinical hold on all NGF inhibitors. Three nonclinical toxicology studies were conducted to evaluate the effects of tanezumab or the murine precursor muMab911 on selected bone and joint endpoints and biomarkers in cynomolgus monkeys, Sprague-Dawley rats, and C57BL/6 mice. Joint and bone endpoints included histology, immunohistochemistry, microcomputed tomography (mCT) imaging, and serum biomarkers of bone physiology. Responses of bone endpoints to tanezumab were evaluated in monkeys at 4 to 30 mg/kg/week for 26 weeks and in rats at 0.2 to 10 mg/kg twice weekly for 28 days. The effects of muMab911 at 10 mg/kg/week for 12 weeks on selected bone endpoints were determined in mice. Tanezumab and muMab911 had no adverse effects on any bone or joint parameter. There were no test article-related effects on bone or joint histology, immunohistochemistry, or structure. Reversible, higher osteocalcin concentrations occurred only in the rat study. No deleterious effects were observed in joints or bones in monkeys, rats, or mice administered high doses of tanezumab or muMab911.

Vascular inflammation, infusion reactions, glomerulopathies, and other potentially adverse effects may be observed in laboratory animals, including monkeys, on toxicity studies of therapeutic monoclonal antibodies and recombinant human protein drugs. Histopathologic and immunohistochemical (IHC) evaluation suggests these effects may be mediated by deposition of immune complexes (ICs) containing the drug, endogenous immunoglobulin, and/or complement components in the affected tissues. ICs may be observed in glomerulus, blood vessels, synovium, lung, liver, skin, eye, choroid plexus, or other tissues or bound to neutrophils, monocytes/macrophages, or platelets. IC deposition may activate complement, kinin, and/or coagulation/fibrinolytic pathways and result in a systemic proinflammatory response. IC clearance is biphasic in humans and monkeys (first from plasma to liver and/or spleen, second from liver or spleen). IC deposition/clearance is affected by IC composition, immunomodulation, and/or complement activation. Case studies are presented from toxicity study monkeys or rats and indicate IHC-IC deposition patterns similar to those predicted by experimental studies of IC-mediated reactions to heterologous protein administration to monkeys and other species. The IHC-staining patterns are consistent with findings associated with generalized and localized IC-associated pathology in humans. However, manifestations of immunogenicity in preclinical species are generally not considered predictive to humans., (© 2014 by The Author(s).)

Purpose: Taprenepag isopropyl is an EP2 receptor agonist that is in development for the treatment of glaucoma. Iritis, photophobia, and increased corneal thickness observed in a Phase 2 clinical trial with taprenepag isopropyl were not previously observed in topical ocular toxicity studies in rabbits and dogs. In vivo studies using cynomolgus monkeys and in vitro models were used to elucidate the mechanisms underlying these ocular events., Methods: Monkeys were dosed daily for 28 days in 1 eye with taprenepag and in the other with vehicle control. Complete ophthalmic examinations were performed at baseline and weekly thereafter. Serial sections of eyes were examined histopathologically at the end of the study. Recovery after the discontinuation of taprenepag was assessed for 28 days in the monkeys in the high-dose group. In vitro studies evaluated cell viability, paracellular permeability, and cytokine induction with human corneal epithelial or endothelial cell cultures., Results: Monkeys demonstrated a dose-related incidence of iritis and increased corneal thickness that resolved within 28 days of discontinuing taprenepag. There was no evidence in vivo of taprenepag toxicity to the corneal endothelium or epithelium. Cell viability of stratified epithelial cells was primarily affected by excipients and was similar to Xalatan(®). The viability of HCEC-12 cells was not affected by taprenepag at concentrations up to 100 μM., Conclusions: The lack of in vivo or in vitro endothelial cytotoxicity and the reversibility of the increase in corneal thickness and iritis in the monkey provide confidence to permit further clinical development of taprenepag.

Background: This study compared infusion set function for up to 1 week using either a Teflon(®) (Dupont(™), Wilmington, DE) catheter or a steel catheter for insulin pump therapy in type 1 diabetes mellitus., Subjects and Methods: Twenty subjects participating in a randomized, open-labeled, crossover study were asked to wear two Quick-Set(®) and two Sure-T(®) infusion sets (both from Medtronic Minimed, Northridge, CA) until the infusion set failed or was worn for 1 week. All subjects wore a MiniMed continuous glucose monitoring system for the duration of the study., Results: One subject withdrew from the study. There were 38 weeks of Sure-T wear and 39 weeks of Quick-Set wear with no difference in the survival curves of the infusion sets. There was, however, a 15% initial failure rate with the Teflon infusion set. After 7 days, both types of infusion sets had a 64% failure rate. Overall, 30% failed because of hyperglycemia and a failed correction dose, 13% were removed for pain, 10% were pulled out by accident, 10% had erythema and/or induration of>10 mm, 5% fell out because of loss of adhesion, and 4% were removed for infection. The main predictor of length of wear was the individual subject. There was no increase in hyperglycemia or daily insulin requirements when an infusion set was successfully used for 7 days (n=25 of 77 weeks)., Conclusions: We found no difference between steel and Teflon infusion sets in their function over 7 days, although 15% of Teflon sets failed because of kinking on insertion. The strongest predictor of prolonged 7-day infusion set function was the individual subject, not the type of infusion set.

Preservatives are used in ocular medications to prevent microbial contamination. The use of benzalkonium chloride (BAC), the most widely used preservative in ocular medications, has been scrutinized with a number of studies indicating its toxicity to monolayer cultures of corneal and conjunctival epithelial cells. The purpose of this study was to evaluate and compare the toxicity of BAC and other preservatives and common components of ocular formulations on monolayer and stratified air-lifted cultures of Chang conjunctival cells. Air-lifting Chang cells grown on transwell filters increased stratification as assessed by transepithelial electrical resistance and histology. Unlike monolayer cultures in which ocular medications containing BAC caused near complete loss of cell viability, stratified, air-lifted cultures were not affected by the presence of BAC in ocular medications with up to 30-min exposures. Stratification shifted the dose-response curve to the right for benzalkonium chloride, thimerosal, chlorhexidine digluconate, potassium sorbate and EDTA. These results demonstrate that stratification significantly affects cell viability of Chang conjunctival cells in response to preservatives and additives of ophthalmic preparations., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Three-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are associated with adverse skeletal muscle effects, but the underlying mechanisms remain unclear. To determine whether toxicity involves the level of drug exposure in muscle tissue and to test the effect of exercise on cerivastatin (CVA)-induced skeletal muscle damage, female rats were administered vehicle or CVA at 0.1, 0.5, and 1.0 mg/kg/day by gavage for two weeks and exercised or not on treadmills for 20 min/day. Clinical chemistry and plasma and tissue pharmacokinetics were evaluated; light and transmission electron microscopy (TEM) of Type I and Type II fiber-predominant skeletal muscles were performed. Serum levels of AST, ALT, CK, and plasma lactic acid were significantly elevated dose-dependently. CVA treatment decreased psoas and quadriceps weights. At 1 mg/kg all muscles except soleus demonstrated degeneration. Exercise-exacerbated severity of CVA-induced degeneration was evident in all muscles sampled except soleus and quadriceps. Early mitochondrial involvement in toxicity is suggested by the numerous membranous whorls and degenerate mitochondria observed in muscles at 0.5 mg/kg. No significant differences in CVA concentrations between either EDL and soleus or plasma and muscle were found. We found that CVA had no effect on cleaved caspase 3. In summary, we found that treadmill exercise exacerbated the incidence and severity of CVA-induced damage in Type II fiber-predominant muscles. Tissue exposure is likely not the key factor mediating CVA-induced skeletal muscle toxicity.

Purpose: The purpose of this study was to characterize the morphological abnormalities in the retinas of chicks (Gallus gallus) suffering from the autosomal recessive disease, retinopathy, globe enlarged (rge/rge)., Methods: rge/rge affected and age matched control retinas were examined from hatch up to 730 days of age. Thickness of retinal layers at six retinal regions was measured from plastic embedded sections. Morphological features were examined on semi-thin sections by light microscopy and on ultra-thin sections by transmission electron microscopy. Immunohistochemistry was performed using a panel of several different antibodies. Additionally, comparative counting of rod outer segments, rows of cells in the inner nuclear layer, and ganglion cells per unit length was performed., Results: The earliest changes observed in rge/rge retinas were disorganization of the outer plexiform layer and abnormal location of the endoplasmic reticulum of the photoreceptors. In rge/rge retinas, cone pedicles were larger, irregular in shape, and usually contained multivesicular bodies. In addition, synaptic ribbons of the cone pedicles and rod spherules in rge/rge retinas were less numerous compared to controls. Large glycogen deposits progressively accumulated in the perinuclear cytoplasm associated with the abnormally located endoplasmic reticuli in accessory cones and rods. Total retinal thickness progressively decreased with age in rge/rge birds. This was accompanied by a decrease in the number of cells in the inner nuclear layer and a decrease in the number of rod outer segments (OSs). Several changes were detected in the rge/rge retinas using immunohistochemistry, including mislocalized opsin immunoreactivity of rod photoreceptors, a decrease in number and disorganization of opsin positive rod OSs (especially in the peripheral regions), a decrease in number of tyrosine hydroxylase positive neurites in the distal inner plexiform layer, and activation of macroglial and microglial cells., Conclusions: As we previously reported, the rge/rge chick has vision loss that is not the result of photoreceptor loss and is unusual in that electroretinographic responses, although abnormal, are maintained until well after vision loss has developed. The phenotype is associated with a developmental disruption of both rod and cone photoreceptor synaptic terminals that progresses with age. It is possible that these changes may be indicative of abnormal circuitry within the outer plexiform layer, and that they underlie the progressive loss of vision in rge/rge birds. Other early changes suggesting photoreceptor abnormality are dilation of photoreceptor cell bodies, abnormal positioning of endoplasmic reticulum in the perinuclear region that is associated with abnormal glycogen deposition, and mislocalization of opsin immunoreactivity in rods. The rge/rge birds develop globe enlargement after the morphological and electroretinographic abnormalities. Globe enlargement in chicks can be induced by a number of different environmental factors. It is possible that abnormal signaling of photoreceptors to inner retinal cells could induce excessive ocular growth in the rge/rge birds. Many of the morphological changes such as retinal thinning seen in older rge/rge birds may be partly the result of the considerable globe enlargement that occurs later in the disease process. Molecular genetic studies to identify the causal gene mutation should help explain the morphological features of the rge/rge phenotype and clarify their association with vision loss and electroretinographic abnormalities.

Osteoarthritis (OA) is a degenerative joint disease characterized by joint pain and a progressive loss of articular cartilage. Studies to elucidate the pathophysiology of OA have been hampered by the lack of a rapid, reproducible animal model that mimics both the histopathology and symptoms associated with the disease. Injection of mono-iodoacetate (MIA), an inhibitor of glycolysis, into the femorotibial joint of rodents promotes loss of articular cartilage similar to that noted in human OA. Here, we describe the histopathology in the subchondral bone and cartilage of rat (Wistar) knee joints treated with a single intra articular injection of MIA (1 mg) and sacrificed at 1, 3, 5, 7, 14, 28, and 56 days postinjection. Histologically, the early time points (days 1-7) were characterized by areas of chondrocyte degeneration/necrosis sometimes involving the entire thickness of the articular cartilage in the tibial plateaus and femoral condyles. Changes to the subchondral bone, as evidenced by increased numbers of osteoclasts and osteoblasts, were noted at by day 7. By 28 days, there was focal fragmentation and collapse of bony trabeculae with fibrosis and increased osteoclastic activity. By 56 days there were large areas of bone remodeling evidenced by osteoclastic bone resorption and newly formed trabeculae with loss of marrow hematopoietic cells. Subchondral cysts and subchondral sclerosis were present in some rats. In conclusion, intra-articular injection of MIA induces loss of articular cartilage with progression of subchondral bone lesions that mimic those of OA. This model offers a rapid and minimally invasive method to reproduce OA-like lesions in a rodent species.

d-Methylphenidate (d-MPH) was approved as a treatment for attention deficit hyperactivity disorder (ADHD) in children. The repeated-dose toxicity of the d enantiomer of d,l-methylphenidate (d,l-MPH) was assessed in male and female Beagle dogs. Dogs were orally dosed twice a day in equally divided doses 6 hours apart for total daily doses of 1, 3, and 10 mg/kg/day d-MPH or 20 mg/kg/day d,l-MPH for 90 days, followed by a 30-day recovery period. The top d-MPH dose of 10 mg/kg was equimolar to 20 mg/kg d,l-MPH in d-MPH content. The 10-mg/kg d-MPH and d,l-MPH doses were at least 13 times the maximum therapeutic dose giving rise to systemic exposures that were equivalent to or at least 2 times greater than those at the maximum therapeutic doses in children. The 10-mg/kg d-MPH and 20-mg/kg d,l-MPH doses had systemic exposures that were equivalent to or two to five times greater than the maximum therapeutic plasma levels in children respectively. There was no treatment-related mortality in all doses tested. Reversible salivation, hyperactivity, and diarrhea were seen in the high-dose d-MPH and d,l-MPH groups. Significant body weight loss and reduction in food consumption were observed in males for both high-dose groups with weights comparable to control values by the end of the recovery period. There were no abnormal clinical pathology or macroscopic or microscopic findings. Based on body weight changes, the no-observed-adverse-effect level (NOAEL) of d-MPH in beagle dogs was 3 mg/kg/day.