RESUMO
Recommendations on study designs that adequately evaluate the in-life effects leading to juvenile bone toxicity, the various imaging modalities that can aid interpretation of the bone effects, biomarkers that may be useful, and regulatory issues were presented in this 2020 ACT symposium. The pathologies encountered in past studies were briefly mentioned. The first speaker covered study design and the numbers of juveniles that may be necessary to power the evaluation. Changes in the International Council for Harmonisation (IHC) guidelines were reviewed. The second speaker launched the rest of the symposium by describing the tools that may help assess juvenile bone toxicity, specifically those used to monitor bone toxicity, healing, and remodeling as they relate or drive the study design including model, species selection, and age. The third speaker addressed in more depth the micro-Computed Tomography (CT) applications in juvenile toxicology for evaluation of skeletal elements and bone growth in both embryo-fetal development (EFD) and pre and postnatal development (PPND) studies. Lastly, a regulatory perspective on strategies to assess juvenile bone toxicity and the concerns of the regulatory agency with respect to these potential changes in the juvenile population was addressed.
Assuntos
Projetos de Pesquisa , Testes de Toxicidade , Testes de Toxicidade/métodos , Microtomografia por Raio-X , Biomarcadores , CicatrizaçãoRESUMO
Nonclinical implantation studies are a common and often critical step for medical device safety assessment in the bench-to-market pathway. Nonclinical implanted medical devices or drug-device combination products require complex macroscopic and microscopic pathology evaluations due to the physical presence of the device itself and unique tissue responses to device materials. The Medical Device Implant Site Evaluation working group of the Society of Toxicologic Pathology's (STP) Scientific and Regulatory Policy Committee (SRPC) was tasked with reviewing scientific, technical, and regulatory considerations for these studies. Implant site evaluations require highly specialized methods and analytical schemes that should be designed on a case-by-case basis to address specific study objectives. Existing STP best practice recommendations can serve as a framework when performing nonclinical studies under Good Laboratory Practices and help mitigate limitations in standards and guidances for implant evaluations (e.g., those from the International Organization for Standardization [ISO], ASTM International). This article integrates standards referenced by sponsors and regulatory bodies with practical pathology evaluation methods for implantable medical devices and combination products. The goal is to ensure the maximum accuracy and scientific relevance of pathology data acquired during a medical device or combination drug-device implantation study.
Assuntos
PolíticasRESUMO
The development of biomaterials, medical device components, finished medical products, and 3-D printed and regenerative medicine products is governed by a variety of international and country-specific standards and guidelines. Of greatest importance to planning, executing, and reporting biocompatibility, safety and efficacy studies for most biomaterials and medical components or products are the International Organization for Standardization guidelines, U.S. Pharmacopeial Convention, ASTM International, and Conformité Européenne (European Conformity) marking. The International Medical Device Regulators Forum publishes harmonized standards similar to the International Council for Harmonization. Good Laboratory Practices are applicable and guidance documents for the development of drugs and biologics can also be relevant to biomaterials, medical device components, and medical products and more recently to products produced by 3-D printing or additive manufacturing. Regenerative products may have medical device-based scaffolding and may be treated as biologics, reflecting the cell and tissue components. This compilation of international standards and guidelines provides toxicologic pathologists, toxicologists, bioengineers, and allied professionals with an overview of and source for important regulatory documents that may apply to the nonclinical development of their products.
Assuntos
Materiais Biocompatíveis/normas , Equipamentos e Provisões/normas , Cooperação Internacional , Teste de Materiais/normas , Legislação de Dispositivos Médicos , Alicerces Teciduais/normas , Animais , Humanos , Cooperação Internacional/legislação & jurisprudência , Impressão Tridimensional , Medicina Regenerativa/legislação & jurisprudência , Medicina Regenerativa/normasRESUMO
A number of issues may arise during the conduct of a study which can complicate interpretation of in vitro and in vivo datasets. Speakers discussed the implications of differing interpretations and how to avoid complicating factors during study planning and execution. Consideration needs to be given to study design factors including defining objectives, consideration of expected pharmacological effects, dose selection and drug kinetics, species used, and vehicle selection. In addition, the effects of vivarium temperature effects on various endpoints, how to control variables affecting clinical pathology, and how early death animals, common background findings, and artifacts can affect histopathology interpretation all play into the final interpretation of study data.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Projetos de Pesquisa , Experimentação Animal , AnimaisRESUMO
As the skin is the primary barrier to infection, the importance of wound healing has been understood since ancient times. This article provides a synopsis on the symposium presentations focusing on how wounds were traditionally treated, what models and pathology endpoints exist to study wound healing, special considerations for wound healing studies, an overview of regulatory aspects of new pharmaceutical and medical device development, and the clinical relevance of such models. The clinical treatment of small and large wounds is also considered.
Assuntos
Cicatrização/efeitos dos fármacos , Animais , Anti-Infecciosos/uso terapêutico , Congressos como Assunto , Modelos Animais de Doenças , Humanos , Pele/efeitos dos fármacos , Pele/microbiologia , Pele/patologia , Infecção dos Ferimentos/tratamento farmacológico , Infecção dos Ferimentos/microbiologia , Ferimentos e Lesões/tratamento farmacológico , Ferimentos e Lesões/microbiologiaRESUMO
Stem cells have great potential in basic research and are being slowly integrated into toxicological research. This symposium provided an overview of the state of the field, stem cell models, described allogenic stem cell treatments and issues of immunogenicity associated with protein therapeutics, and tehn concentrated on stem cell uses in regenerative medicine focusing on lung and testing strategies on engineered tissues from a pathologist's perspective.
Assuntos
Pesquisa com Células-Tronco , Células-Tronco , Animais , Diferenciação Celular , Congressos como Assunto , Modelos Animais de Doenças , Humanos , Medicina Regenerativa , Engenharia Tecidual , Transplante HomólogoRESUMO
BACKGROUND: A new scaffold design combined with a peptide growth factor was tested prospectively for safety and for improved tendon healing in sheep. METHODS: The infraspinatus tendon was detached and then surgically repaired to the humerus using sutures and anchors in 50 adult sheep. The repairs in 40 of these sheep were reinforced with a scaffold containing F2A, a peptide mimetic of basic fibroblast growth factor. The sheep were examined after 8 or 26 weeks with magnetic resonance imaging, full necropsy, and histopathologic analysis. A second cohort of 30 sheep underwent surgical repair--20 with scaffolds containing F2A. The 30 shoulders were tested mechanically after 8 weeks. RESULTS: The scaffold and F2A showed no toxicity. Scaffold-repaired tendons were 31% thicker than surgically repaired controls (P = .037) at 8 weeks. There was more new bone formed at the tendon footprint in sheep treated with F2A. Surgically repaired tendons delaminated from the humerus across 14% of the footprint area. The extent of delamination decreased to 1.3% with increasing doses of F2A (P = .004). More of the repair tissue at the footprint was tendon-like in the peptide-treated sheep. On mechanical testing, only 7 shoulders tore at the repair site. The repairs in the other 23 shoulders were already stronger than the midsubstance tendon at 8 weeks. CONCLUSIONS: The new scaffold and peptide safely improved tendon healing.
Assuntos
Implantes Absorvíveis , Colágeno Tipo I/administração & dosagem , Fator 2 de Crescimento de Fibroblastos/administração & dosagem , Tendões/cirurgia , Alicerces Teciduais , Animais , Regeneração Óssea , Imageamento por Ressonância Magnética , Modelos Animais , Estudos Prospectivos , Ovinos , Tendões/patologia , Resistência à TraçãoRESUMO
This continuing education course presented at the Society of Toxicologic Pathology's 31st Annual Symposium explored and defined the many roles that toxicologic pathologists serve Good Laboratory Practice (GLP)-conducted toxicology and carcinogenicity studies.
Assuntos
Patologia/normas , Toxicologia/normas , Avaliação Pré-Clínica de MedicamentosRESUMO
Female Fischer 344 (F344) rats were exposed to N-nitrosodiphenylamine (NDPA) by dietary feed at concentrations of 0, 250, 1000, 2000, 3000 or 4000 ppm for 5 days, 2, 4 and 13 weeks duration. Endpoints evaluated included clinical observations, body weights, urinary bladder weights, blood NDPA, gross pathology and urinary bladder histopathology. There were no NDPA exposure-related clinical signs of toxicity. The mean body weight decreased 3% to 5% compared with the control in the 4000 ppm group during study weeks 2 through to 13. Statistically significant increases in urinary bladder weight were observed as early as after 5 days exposure and were concentration dependent at ≥ 3000 ppm. NDPA-related urinary bladder microscopic alterations consisted of mixed cell infiltrates, increased mitosis, increased necrosis of epithelial cells, diffuse and/or nodular transitional epithelial hyperplasia and squamous metaplasia of transitional epithelium. These changes affected only rats exposed to NDPA concentrations ≥ 2000 ppm. Blood NDPA concentrations were negligible in animals exposed to ≤ 1000 ppm and ranged from 0.12 to 0.19 µg ml(-1) in rats of the ≥ 2000 ppm groups at the 5 days and 2 weeks time points. A no observable adverse effect level (NOAEL) of 1000 ppm NDPA (60 mg kg(-1) day(-1) ) was selected based on the absence of urinary bladder histopathology.
Assuntos
Nitrosaminas/toxicidade , Testes de Toxicidade Subcrônica , Bexiga Urinária/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Determinação de Ponto Final , Feminino , Masculino , Nível de Efeito Adverso não Observado , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Endogâmicos F344 , Bexiga Urinária/metabolismo , Bexiga Urinária/patologiaRESUMO
Female F344 rats were exposed to 4,4'-methylenebis(N,N'-dimethyl)aniline (MDA) by dietary feed at concentrations of 0, 50, 200, 375, 500, or 750 ppm for 5 d, 2 wk, 4 wk, and 13 wk duration. Endpoints evaluated included clinical observations, body weights, thyroid weights, serum thyroid hormones, blood MDA, gross pathology, and thyroid histopathology. There were no MDA exposure-related clinical signs of toxicity. Mean body weight decreased 5% compared to control in the 750 ppm group during study wk 6 through 13. Serum TSH increased and serum T4 and T3 levels decreased with increasing feed concentrations of MDA and time of exposure. Thyroid weight increases were both concentration- and exposure time-dependent and statistically significant at ≥375 ppm. Incidence and severity of decreased colloid, follicular cell hypertrophy and follicular cell hyperplasia were also related to MDA concentration and exposure time. A no-observed-adverse-effect level (NOAEL) of 200 ppm was selected based on the statistically significant increase in incidence of follicular cell hyperplasia at concentrations ≥375 ppm.
Assuntos
Compostos de Anilina/toxicidade , Indicadores e Reagentes/toxicidade , Glândula Tireoide/efeitos dos fármacos , Administração Oral , Compostos de Anilina/administração & dosagem , Compostos de Anilina/sangue , Compostos de Anilina/farmacocinética , Animais , Carcinógenos/administração & dosagem , Carcinógenos/análise , Carcinógenos/farmacocinética , Carcinógenos/toxicidade , Relação Dose-Resposta a Droga , Poluentes Ambientais/administração & dosagem , Poluentes Ambientais/sangue , Poluentes Ambientais/farmacocinética , Poluentes Ambientais/toxicidade , Feminino , Hiperplasia , Hipertrofia , Indicadores e Reagentes/administração & dosagem , Indicadores e Reagentes/análise , Indicadores e Reagentes/farmacocinética , Nível de Efeito Adverso não Observado , Tamanho do Órgão/efeitos dos fármacos , Distribuição Aleatória , Ratos , Ratos Endogâmicos F344 , Glândula Tireoide/crescimento & desenvolvimento , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/induzido quimicamente , Tireotropina/sangue , Tiroxina/sangue , Tri-Iodotironina/sangueRESUMO
Male Sprague-Dawley rats were exposed to 1,2,4-tribromobenzene (TBB) by gavage for 5 days, 2, 4, and 13 weeks at 0, 2.5, 5, 10, 25, or 75 mg/kg per d. There were no TBB exposure-related clinical signs of toxicity or changes in body weight. Liver weight increases were dose and exposure time related and statistically significant at ≥10 mg/kg per d. Incidence and severity of centrilobular cytoplasmic alteration and hepatocyte hypertrophy were dose and time related. The 75 mg/kg per d group had minimally increased mitoses within hepatocytes (5 days only). Hepatocyte vacuolation was observed (13 weeks) and was considered TBB exposure related at ≥25 mg/kg per d. Concentrations of blood TBB increased linearly with dose and at 13 weeks, ranged from 0.5 to 17 µg/mL (2.5-75 mg/kg per d). In conclusion, rats administered TBB doses of 10-75 mg/kg per d for 13 weeks had mild liver effects. A no observed adverse effect level of 5 mg/kg per d was selected based on the statistically significant incidence of hepatocyte hypertrophy at doses ≥10 mg/kg per d.
Assuntos
Bromobenzenos/toxicidade , Fígado/efeitos dos fármacos , Animais , Bromobenzenos/sangue , Bromobenzenos/farmacocinética , Fígado/patologia , Masculino , Nível de Efeito Adverso não Observado , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Testes de Toxicidade SubcrônicaRESUMO
Toxicity studies of intranasally administered, live attenuated influenza virus vaccine candidates conducted in male and female ferrets led to the microscopic observation of individual differences in the size of nasal turbinates, especially in the dorsal aspect of the nasal cavity. The association of these enlarged turbinates with acute to subacute inflammation, which is sometimes common in ferrets given live attenuated influenza virus vaccine candidates, led to this detailed microscopic evaluation of turbinate enlargement (cartilaginous and osseous thickening, or COT) in control animals dosed intranasally with saline. Results of this evaluation led to the conclusion that COT is a normal developmental feature of growing ferrets, irrespective of inflammation in nasal tissues or inflammatory exudate in the nasal cavity.
Assuntos
Furões/crescimento & desenvolvimento , Conchas Nasais/crescimento & desenvolvimento , Animais , Calcificação Fisiológica/fisiologia , Proliferação de Células , Feminino , Hipertrofia , Masculino , Cavidade Nasal/anatomia & histologia , Osteogênese/fisiologia , Estudos Retrospectivos , Rinite/patologia , Conchas Nasais/anatomia & histologia , Conchas Nasais/fisiologiaRESUMO
The prophylactic use of zidovudine (3'-azido-3'-deoxythymidine, AZT) during pregnancy greatly reduces transmission of HIV-1 from infected mothers to their infants; however, the affinity of host cell DNA polymerases for AZT also allows for its incorporation into host cell DNA, predisposing to cancer development. To expand upon previous transplacental carcinogenesis assays performed in CD-1 mice, the transplacental carcinogenicity of AZT was evaluated in a second mouse strain and a second rodent species. Date-mated female mice and rats were gavaged daily with 0, 80, 240, or 480 mg AZT/kg bw during the last 7 days of gestation. At 2 years postpartum, male and female B6C3F1 mouse and F344 rat offspring (n = 44-46 of each sex and species/treatment group) were necropsied for gross and microscopic tissue examinations. Under the conditions of these two-year studies, there was clear evidence of carcinogenic activity based upon significant dose-related trends and increases in the incidences of hemangiosarcoma in male mice and mononuclear cell leukemia in female rats. There was some evidence of carcinogenic activity in the livers of male mice based upon a positive trend and an increased incidence of hepatic carcinoma in the high-dose AZT group. The incidence of gliomas in female rats exceeded the historical background rates for gliomas in F344 rats. P53 overexpression was detected in some AZT-treated mouse neoplasms. These and other cancer-related findings confirm and extend those of previous transplacental carcinogenicity studies of AZT in mice, support the need for long-term follow-up of nucleoside reverse transcriptase inhibitor (NRTI)-exposed children, and indicate the necessity for effective protective strategies against NRTI-induced side effects.
Assuntos
Fármacos Anti-HIV/toxicidade , Carcinógenos/toxicidade , Neoplasias/induzido quimicamente , Inibidores da Transcriptase Reversa/toxicidade , Zidovudina/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Feminino , Masculino , Troca Materno-Fetal , Camundongos , Camundongos Endogâmicos , Neoplasias/metabolismo , Neoplasias/patologia , Gravidez , Ratos , Ratos Endogâmicos F344 , Proteína Supressora de Tumor p53/metabolismoRESUMO
In 1989, an epidemic of eosinophilia-myalgia syndrome (EMS) occurred in the United States that was attributed to contaminated l-tryptophan (LT). Features of tryptophan-induced EMS included debilitating myalgia and marked peripheral eosinophilia. Although the contaminant(s) was found only in the product produced by a single manufacturer (Showa Denko), all LT was withdrawn from the market and replaced by 5 hydroxytryptophan (5HTP). The belief was that the latter should not contain the implicated contaminant(s), because it was manufactured by a process entirely different from the banished LT. Nevertheless, in 1994 a case diagnosed as EMS appeared. Although the exact causative factor(s) in LT and the possible 5-HTP-induced EMS are uncertain, many reported finding "Peak E" in contaminated LT and the presence of "Peak X" in the 5-HTP of the 1994 case. The latter finding led some to assume that Peak X was a potential pathological agent in 5-HTP that might cause future cases of EMS. To determine whether 5-HTP could cause EMS, we followed 120 male Sprague-Dawley rats, 7 to 8 weeks of age (body weight 200-250 g), for 1 year. They were divided into three groups of 40. One group acted as control, drinking only water; a second group received a low dose of 5-HTP in their drinking water (87.5 mg/dL); and the last group drank a high dose of 5-HTP, 875 mg/dL. No significant differences in the body weights of these three groups of animals were observed over the year. After 2 months, systolic blood pressures (SBP) in the 5-HTP groups were significantly lower for the duration of the study. At the end of 12 months, SBP of the control group averaged 140 mm Hg, the low-dose 5-HTP group averaged 133 mm Hg, and the high-dose group averaged 125 mm Hg. Even though enough 5-HTP was given to cause a physiological response, no significant differences were found in the hematological values, including eosinophil count. Also, no significant differences were found in hepatic and renal values. In the histological studies, no treatment-related changes were noted in the hearts, livers, pancreases, leg striated muscles, and small intestines. In particular, there was no evidence of eosinophilic infiltration and fascial/perimysial inflammation. Accordingly, no significant evidence of EMS was seen in rats receiving high-dose 5-HTP for 1 year.
RESUMO
A recent study further investigated the potential effects of maternal thyroid function and morphology on fetal development upon maternal exposure to ammonium perchlorate during gestation and lactation. Female Sprague-Dawley rats (25/group) were given continual access to 0 (carrier), 0.01, 0.1, 1.0, and 30.0 mg/kg-day perchlorate in drinking water beginning 2 weeks prior to cohabitation through lactation day 10. Maternal, fetal, and pup serum thyroid hormone (thyroid-stimulating hormone [TSH], triiodo thyronine [T(3)], thyroxine [T(4)]) levels and thyroid histopathology were evaluated on gestation day 21, and lactation days 5, 10, and 22. No effects of exposure were observed on cesarean-sectioning, litter parameters, or fetal alterations. Reproductive parameters, including gestation length, number of implants, litter size, pup viability, and lactation indices, were comparable among all groups. Thyroid weights of dams sacrificed on gestation day 21, and lactation days 10 and 22 were significantly increased at 30.0 mg/kg-day. Increased thyroid weights were observed in male and female pups as early as postpartum days 5 and 10, respectively. Changes in maternal and neonatal thyroid histopathology were detectable at 1.0 mg/kg-day exposure. The maternal no-observable-effect level (NOEL) was 0.1 mg/kg-day (follicular cell hyperplasia was present at 1.0 and 30.0 mg/kg-day). The developmental NOEL was less than 0.01 mg/kg-day; thyroid weights of postpartum day 10 pups were increased at all exposures. Colloid depletion at 1.0 and 30.0 mg/kg-day exposures and changes of hormone levels at all exposures were considered an adaptive effect and appeared reversible in the rodent.
Assuntos
Percloratos/toxicidade , Efeitos Tardios da Exposição Pré-Natal , Compostos de Amônio Quaternário/toxicidade , Reprodução/efeitos dos fármacos , Glândula Tireoide/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Administração Oral , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Feminino , Lactação , Masculino , Exposição Materna , Nível de Efeito Adverso não Observado , Tamanho do Órgão/efeitos dos fármacos , Percloratos/administração & dosagem , Gravidez , Compostos de Amônio Quaternário/administração & dosagem , Ratos , Ratos Sprague-Dawley , Glândula Tireoide/crescimento & desenvolvimento , Glândula Tireoide/patologia , Tireotropina/sangue , Tiroxina/sangue , Tri-Iodotironina/sangue , Poluentes Químicos da Água/administração & dosagemRESUMO
A developmental toxicity study was conducted with ammonium perchlorate (AP) in the drinking water at doses of 0.0, 0.01, 0.1, 1.0, and 30.0 mg/kg-day beginning 14 days before cohabitation and continuing through sacrifice. Twenty-four rats/group were cesarean-sectioned on day of gestation (DG) 21 and fetuses examined for visceral and skeletal alterations. An additional 16 litters/group were sacrificed on DG 21 for maternal and fetal serum TSH, T(3), and T(4) (thyroid-stimulating hormone, triiodothyronine, and thyroxine) levels and thyroid histopathology. Clinical and necropsy observations, body weights, feed and water consumption, and cesarean-sectioning parameters were comparable among the groups with only delays in ossification observed in the 30 mg/kg-day group. Maternal thyroid weights were increased in the 30.0 mg/kg-day group. Decreased colloid was present in male and female fetal thyroids in the 1.0 and 30.0 mg/kg-day groups. Maternal TSH was increased and T(4) was decreased at all levels, and T(3) was reduced at 30.0 mg/kg-day. Fetal TSH was increased at 1.0 and 30.0 mg/kg-day, T(4) was reduced at 30.0 mg/kg-day, and T(3) was decreased at all levels. The maternal no-observable-adverse-effect level (NOAEL) was 1.0 mg/kg-day; exposures of 30.0 mg/kg-day increased absolute and relative maternal thyroid weights and histopathology findings. The developmental NOAEL was 1.0 mg/kg-day; developmental delays in ossification occurred in the 30.0 mg/kg-day group. The colloid depletion in the thyroids and increased TSH and decreased T(3) and T(4) levels at lower exposures were considered adaptive and not adverse. No adverse effects on development at occurred levels that did not cause maternal toxicity. AP is not a selective developmental toxicant.