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1.
J Small Anim Pract ; 65(6): 361-367, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38441325

RESUMO

OBJECTIVES: To use text mining approaches to identify instances of suspected adverse drug reactions recorded in first opinion veterinary free-text clinical narratives, and to evaluate whether these were also reported to either the Veterinary Medicines Directorate or the relevant Marketing Authorisation holder in order to derive an estimate of the suspected adverse drug reaction (sADR) minimum under-reporting rate. To characterise sADR reports and explore whether particular features are associated with report submission. MATERIALS AND METHODS: Two regular expressions were developed to identify mentions of "adverse drug reactions" and "side effects" in the free-text clinical narratives of electronic health records contained within the Small Animal Veterinary Surveillance Network database. Consultations containing a match for the developed regular expressions were manually reviewed for inclusion and further classified to determine the suspected product, seriousness and expectedness of the event, and an indication of whether the event had been reported. The associations between event characteristics and reporting were explored using Fisher's exact tests. RESULTS: A total of 10,565 records were manually reviewed from which 827 sADRs were identified. Approximately 90% of these sADRs were not recorded as reported. Suspected adverse drug reactions that were not considered "expected" were recorded as reported more frequently than "expected" sADRs. However, clinical severity did not appear to impact on whether there was a record of reporting. CLINICAL SIGNIFICANCE: This is the first estimate of under reporting sADRs based on real world evidence from veterinary clinical records. The under-reporting rate implied by this study highlights that further interventions are required to improve reporting rate within the veterinary profession in order to support pharmacovigilance activities and improve drug safety.


Assuntos
Sistemas de Notificação de Reações Adversas a Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Sistemas de Notificação de Reações Adversas a Medicamentos/estatística & dados numéricos , Animais , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/veterinária , Mineração de Dados , Drogas Veterinárias/efeitos adversos , Registros Eletrônicos de Saúde , Medicina Veterinária , Farmacovigilância
2.
J Small Anim Pract ; 63(2): 113-119, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34617607

RESUMO

OBJECTIVES: To determine the diagnostic accuracy of ultrasonography in the detection of lymphomatous infiltration of the liver and spleen in a population of dogs and cats with lymphoma. To determine if specific ultrasonographic features of the liver and spleen in dogs are associated with lymphomatous infiltration or a specific immunophenotype of multi-centric lymphoma. MATERIALS AND METHODS: A blinded retrospective evaluation of ultrasonographic images of the liver and/or spleen in dogs and cats with cytologically or histologically confirmed lymphoma was performed by two board-certified veterinary radiologists. RESULTS: A total of 161 animals met the inclusion criteria, comprising 132 dogs and 29 cats. Ultrasonography had a sensitivity, specificity, accuracy, positive predictive value and negative predictive value of 16.7%, 91.0%, 55.9%, 62.5% and 55.0% for the detection of lymphomatous infiltration of the liver, and 73.1%, 93.9%, 82.6%, 93.4% and 74.7% for the spleen. In dogs, an ultrasonographically normal liver was associated with not having lymphomatous infiltration, leopard-spotted splenic parenchyma and splenomegaly were independently associated with lymphomatous infiltration and leopard-spotted splenic parenchyma was also associated with the B cell immunophenotype of multi-centric lymphoma. CLINICAL SIGNIFICANCE: Ultrasonography of the spleen and liver is specific but not sensitive in the detection of lymphomatous infiltration. A leopard-spotted splenic parenchyma in dogs is highly specific for lymphomatous infiltration and in this population predicted a specific immunophenotype of multi-centric lymphoma.


Assuntos
Doenças do Gato/diagnóstico por imagem , Doenças do Cão/diagnóstico por imagem , Neoplasias Hepáticas/veterinária , Linfoma/veterinária , Neoplasias Esplênicas/veterinária , Animais , Doenças do Gato/patologia , Gatos , Doenças do Cão/patologia , Cães , Fígado/diagnóstico por imagem , Fígado/patologia , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/patologia , Linfoma/diagnóstico por imagem , Linfoma/patologia , Estudos Retrospectivos , Sensibilidade e Especificidade , Neoplasias Esplênicas/diagnóstico por imagem , Ultrassonografia/veterinária
3.
J Small Anim Pract ; 62(7): 507-520, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33974272

RESUMO

Molecular pathology is a developing sub-microscopic discipline of pathology that studies the effects of molecular variations and mutations on disease processes. The ultimate goal of molecular pathology in cancer is to predict risk, facilitate diagnosis and improve prognostication based on a complete understanding of the biological impact of specific molecular variations, mutations and dysregulations. This knowledge will provide the basis for customised cancer treatment, so-called precision medicine. Rapid developments in genomics have placed this field at the forefront of clinical molecular pathology and there are already a number of well-established genetic tests available for clinical use including PCR of antigen receptor rearrangement and KIT mutational analysis. Moving beyond tests assessing a single gene, there are significant research efforts utilising genomics to predict cancer risk, forecast aggressive behaviour and identify druggable mutations and therapeutic biomarkers. Researchers are also investigating the use of circulating cells and nucleic acid for clinically useful low morbidity genomic assessments. If we are to realise the full potential of molecular pathology and precision medicine there are a number of challenges to overcome. These include developing our understanding of the underlying biology (in particular intra-tumoural heterogeneity), methodological standardisation of assays, provision of adequate infrastructure and production of novel therapeutics backed by high-quality clinical data supporting the precision medicine approach. The era of molecular pathology holds the potential to revolutionise veterinary cancer care, but its impact on clinical practice will depend upon the extent to which the inherent challenges can be overcome.


Assuntos
Neoplasias , Patologia Molecular , Animais , Genômica , Mutação , Neoplasias/genética , Neoplasias/veterinária , Medicina de Precisão/veterinária
4.
Aust Vet J ; 98(3): 69-78, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31769013

RESUMO

OBJECTIVE: Cytarabine, a cell-cycle phase-specific antimetabolite, has been reported to improve outcomes in dogs with bone marrow (BM) or central nervous system (CNS) lymphoma involvement receiving combination chemotherapy. The objective of this study was to evaluate the incidence and severity of toxicity of cytarabine constant rate infusion (CRI) in dogs with high-grade non-Hodgkin lymphoma. METHODS: Medical records of canine lymphoma patients with confirmed or suspected BM (group 1) or CNS (group 2) involvement, treated with a modified cyclophosphamide, epirubicin, vincristine and prednisolone protocol, including a single dose of cytarabine given as CRI, were reviewed and adverse events graded. RESULTS: Twenty-six dogs were included. Gastrointestinal toxicity occurred in 17 dogs (65.3%), with 5 (19.2%) experiencing grade III or IV toxicity. Neutropenia occurred in nine dogs (34.6%), but was grade I or II in most cases. Three dogs (11.5%) had thrombocytopenia: one grade III and two grade IV. Four dogs (15.3%) experienced increases in alanine amino transferase: one each grade I and II and two grade III. Five dogs (19.2%) required hospitalisation to manage toxicity after completing cytarabine CRI, and haematological toxicity resulted in treatment delays in five dogs (median delay of 4 days, range: 3-7 days). CONCLUSION: Our findings suggest that gastrointestinal toxicity should be expected in lymphoma patients undergoing cytarabine CRI.


Assuntos
Doenças do Cão/tratamento farmacológico , Linfoma não Hodgkin/veterinária , Animais , Protocolos de Quimioterapia Combinada Antineoplásica , Medula Óssea , Citarabina/uso terapêutico , Cães , Sistema Nervoso
5.
J Small Anim Pract ; 60(9): 534-542, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31245847

RESUMO

OBJECTIVES: To determine whether dogs with surgically excised mast cell tumours receiving a vinblastine/prednisolone chemotherapy protocol in combination with radiation therapy are at greater risk of myelosuppression than patients receiving the chemotherapy protocol alone. MATERIALS AND METHODS: Retrospective study of clinical records of dogs with mast cell tumours that, subsequent to surgical excision, had received combination vinblasine/prednisolone chemotherapy. Dogs were assigned to two groups: those treated with adjunctive radiotherapy and vinblastine/prednisolone (RT group) and those treated with surgery followed by vinblastine/prednisolone alone (control group). Haematology results were compared between groups. RESULTS: Forty-three cases and 43 controls of similar breed, age and bodyweight were included. Concurrent radiation and vinblastine chemotherapy did not appear to increase the risk of neutropenia, which was observed in 18.6 and 23.2% of cases in the RT and control groups, respectively. CLINICAL SIGNIFICANCE: Radiation and vinblastine chemotherapy can be safely combined in dogs with mast cell tumours without increasing the risk of clinically important myelosuppression.


Assuntos
Doenças do Cão/tratamento farmacológico , Hematologia , Neoplasias/veterinária , Animais , Protocolos de Quimioterapia Combinada Antineoplásica , Cães , Mastócitos , Prednisolona/uso terapêutico , Estudos Retrospectivos , Resultado do Tratamento , Vimblastina/uso terapêutico
6.
J Comp Pathol ; 162: 50-58, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30060843

RESUMO

BRCA1-associated protein-1 (BAP1) is a nuclear localized deubiquitylating enzyme that belongs to the ubiquitin c-terminal hydrolase subfamily. The encoded protein is highly homologous between man and dogs, suggesting a functional significance preserved by evolution. BAP1 has multiple properties, including tumour suppressor activity. Loss of BAP1 function is implicated in the oncogenesis of several types of cancers including uveal, mucosal and some cutaneous melanomas in humans, as well as in mesothelioma. In this study we investigate the significance of BAP1 in canine melanoma. Nuclear BAP1 protein was detected in five canine oral melanoma cell lines using an antibody commonly used for analysis of human tissues. BAP1 loss of function mutations often lead to loss of nuclear BAP1 (nBAP1) expression in humans; this is associated with a poorer prognosis in uveal and mucosal melanoma. Therefore, as a prelude to a study evaluating the prognostic significance of nBAP1 expression in dogs, immunohistochemistry (IHC) was used to assess cases of canine melanoma for nBAP1 expression. In 89 cases where tumour cells were identified by melan-A labelling, 100% of tumour cells were positive for nBAP1 expression, including eight uveal tract and 29 oral mucosal melanomas. This finding indicates that BAP1 IHC cannot be used as a prognostic marker in canine uveal and mucosal melanoma. Moreover, this observation suggests that either BAP1 has a different functional significance in canine melanoma or that loss of BAP1 function is achieved by a different route. This is a novel finding that warrants further investigation to determine the comparative biological relevance.


Assuntos
Biomarcadores Tumorais/análise , Doenças do Cão/diagnóstico , Melanoma/veterinária , Proteínas Supressoras de Tumor/biossíntese , Ubiquitina Tiolesterase/biossíntese , Animais , Linhagem Celular Tumoral , Cães , Humanos , Prognóstico
7.
Vet Comp Oncol ; 16(4): 431-440, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29761612

RESUMO

Mast cell tumours (MCTs) are commonly treated with radiation therapy, most often in a microscopic disease setting. Poorer outcomes are expected in patients with gross disease, and irradiation of gross disease may be associated with greater toxicity. The aim of this study was to compare acute radiation adverse events (AE) in dogs with gross and microscopic MCTs receiving radiotherapy. Fifty-seven dogs were included, 28 with gross disease and 29 with microscopic. In order to assess mucosal and skin toxicity, patients were assigned to 2 groups: head (29 patients, 14 patients with gross and 15 microscopic) and other sites (28 patients, 14 each). All were treated with external beam radiotherapy, and toxicity assessed at the end of treatment and 10 to 14 days later (first recheck). All patients developed some acute radiation toxicity by the end of the course. However, there was no difference in the severity of toxicity between gross and microscopic disease in either site group at either time point. The only variable associated with an increased frequency of grade 2 or 3 toxicity at the first recheck was the use of prednisolone prior to radiotherapy (P = .05). No other factors were identified which were associated with increased toxicity. For the head group, the site of highest grade toxicity was mucosa or, if included in the field, nasal planum, which was often more severely affected than the mucosa. No significant late toxicity was identified. Two dogs developed acute haematemesis during the radiotherapy course, but both completed the course without further events.


Assuntos
Doenças do Cão/radioterapia , Mastocitose Sistêmica/veterinária , Lesões por Radiação/veterinária , Radioterapia/veterinária , Animais , Doenças do Cão/patologia , Cães , Feminino , Masculino , Mastocitose Sistêmica/patologia , Mastocitose Sistêmica/radioterapia , Gradação de Tumores/veterinária , Lesões por Radiação/patologia , Radioterapia/efeitos adversos
8.
Vet Comp Oncol ; 16(3): 361-369, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29380942

RESUMO

The standard of care treatment for canine lymphoma is multi-agent chemotherapy containing prednisolone, cyclophosphamide, vincristine and an anthracycline such as doxorubicin (CHOP) or epirubicin (CEOP). Lomustine, vincristine, procarbazine, and prednisone (LOPP) has been evaluated as a rescue, with encouraging results; however, resistance to vincristine is likely in patients relapsing on CHOP/CEOP, and this agent may enhance LOPP toxicity without improving efficacy. The aim of this study was to evaluate responses to a modified-LOPP protocol that does not include vincristine (LPP) and is administered on a 21-day cycle. Medical records of dogs with high-grade multicentric lymphoma from 2012 to 2017 were reviewed. Dogs with relapsed lymphoma that received LPP as a rescue protocol were enrolled. Response, time from initiation to discontinuation (TTD) and toxicity of LPP were assessed. Forty-one dogs were included. Twenty-five dogs (61%) responded to LPP including 12 complete responses (CR) and 13 partial responses (PR). Responders had a significantly longer TTD (P < .001) compared to non-responders with 84 days for CR and 58 days for PR. Neutropenia was documented in 20 dogs (57%): 12 grade I to II, 8 grade III to IV. Thrombocytopenia was infrequent (20%): 5 grade I to II, 2 grade III to IV. Twelve dogs developed gastrointestinal toxicity (30%): 10 grade I to II and 2 grade III. Nineteen dogs had elevated ALT (59%): 9 grade I to II, 10 grade III to IV. Treatment was discontinued due to toxicity in 8 dogs (19%). The LPP protocol shows acceptable efficacy and toxicity-profile and minimizes in-hospital procedures.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Doenças do Cão/tratamento farmacológico , Lomustina/administração & dosagem , Linfoma não Hodgkin/veterinária , Prednisolona/administração & dosagem , Procarbazina/administração & dosagem , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Cães , Feminino , Lomustina/uso terapêutico , Linfoma não Hodgkin/tratamento farmacológico , Masculino , Neutropenia/induzido quimicamente , Prednisolona/uso terapêutico , Procarbazina/uso terapêutico , Recidiva , Resultado do Tratamento
9.
Vet Comp Oncol ; 15(3): 868-880, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27001524

RESUMO

One of the primary objectives of the Oncology Pathology Working Group (OPWG), a joint initiative of the Veterinary Cancer Society and the American College of Veterinary Pathologists, is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects of and provide guidelines for oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup's particular focus. In this document, the authors provide descriptions of the literature reviewed, the review process, and a summary of the information gathered on immunocytochemistry. The intent of this publication is to help educate practitioners and pathologists on the process of immunocytochemistry and to provide a guide for the use of this technique in veterinary medicine. This document represents the opinions of the working group and the authors and does not constitute a formal endorsement by the American College of Veterinary Pathologists or the Veterinary Cancer Society.


Assuntos
Imuno-Histoquímica/veterinária , Neoplasias/veterinária , Patologia Veterinária/métodos , Animais , Anticorpos/imunologia , Imuno-Histoquímica/métodos , Imuno-Histoquímica/tendências , Neoplasias/imunologia , Neoplasias/patologia , Patologia Veterinária/tendências , Guias de Prática Clínica como Assunto
10.
Vet Comp Oncol ; 15(3): 1041-1050, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27278115

RESUMO

Radiotherapy represents the standard of care for intranasal carcinomas. Responses to tyrosine kinase inhibitors (TKIs) have been reported but data on expression of target receptor tyrosine kinases (rTKs) is limited. This study characterizes the expression of vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR)-α and PDGFR-ß in canine intranasal carcinomas. Histological samples from 187 dogs were retrieved. Immunohistochemistry was performed using commercially available antibodies. Expression of rTKs was classified into weak, moderate or intense and additionally recorded as cytoplasmic, membranous, cytoplasmic-membranous, nuclear or stromal. VEGFR was expressed in 158 dogs with predominantly moderate expression (36.9%) and a cytoplasmic-membranous expression pattern (70.9%). PDGFR-α was detected in 133 with predominantly weak expression (57.9%) and cytoplasmic pattern (87.9%). PDGFR-ß was identified in 74 patients with a predominantly moderate expression (17.6%) and cytoplasmic expression pattern (63.5%). Co-expression of rTKs was common. These results confirm expression of VEGFR, PDGFR-α and PDGFR-ß in canine intranasal carcinomas and support the utility of TKIs.


Assuntos
Doenças do Cão/metabolismo , Neoplasias Nasais/veterinária , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Animais , Doenças do Cão/patologia , Cães , Feminino , Masculino , Neoplasias Nasais/metabolismo , Neoplasias Nasais/patologia , Análise Serial de Tecidos/veterinária
11.
J Small Anim Pract ; 56(4): 229-41, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25704119

RESUMO

Over the last 50 years, the significance of the immune system in the development and control of cancer has been much debated. However, recent discoveries provide evidence for a role of immunological mechanisms in the detection and destruction of cancer cells. Forty years ago veterinary oncologists were already investigating the feasibility of treating neoplasia by enhancing anticancer immunity. Unfortunately, this research was hindered by lack of a detailed understanding of cancer immunology, this limited the specificity and success of these early approaches. The great forward strides made in our understanding of onco-immunology in recent years have provided the impetus for a resurgence of interest in anticancer immunotherapy for canine patients. In this article both these initial trials and the exciting novel immunotherapeutics currently in development are reviewed.


Assuntos
Doenças do Cão/terapia , Imunoterapia/veterinária , Neoplasias/veterinária , Animais , Cães , Desenho de Fármacos , Imunoterapia/tendências , Neoplasias/terapia
12.
Vet Comp Oncol ; 10(2): 113-23, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22236353

RESUMO

Epirubicin is a stereoisomer of doxorubicin that is widely used in human oncology. The purpose of this study was to evaluate the toxicity associated with epirubicin administration in dogs. Three hundred and fifteen treatments were administered to 139 dogs. Patients received between one and seven doses. One hundred and sixteen treatments were associated with toxicity in 81 patients (50 episodes of lethargy, 49 of diarrhoea, 42 of vomiting, 40 of anorexia, 2 hypersensitivity reactions and 2 suspected extravasations). Thirty-six (11%) adverse events resulted in hospitalization in 33 (24%) patients, of which 15 were neutropenic and 9 pyrexic. Mean duration of hospitalization was 3.4 days and 33 patients recovered uneventfully. Owners of 11 patients declined further treatment after toxicity occurred. After 25 treatments associated with toxicity, dose reductions reduced toxicity. The use of prophylactic anti-emetics, gastroprotectants and antibiotics did not reduce the frequency of gastrointestinal toxicity.


Assuntos
Antibióticos Antineoplásicos/efeitos adversos , Antibióticos Antineoplásicos/uso terapêutico , Doenças do Cão/tratamento farmacológico , Epirubicina/efeitos adversos , Epirubicina/uso terapêutico , Neoplasias/veterinária , Animais , Cães , Feminino , Febre/induzido quimicamente , Febre/veterinária , Gastroenteropatias/induzido quimicamente , Gastroenteropatias/veterinária , Masculino , Neoplasias/tratamento farmacológico , Neutropenia/induzido quimicamente , Neutropenia/veterinária , Estudos Retrospectivos
13.
J Small Anim Pract ; 52(9): 469-75, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21896021

RESUMO

OBJECTIVE: To assess whether wounds from incomplete mast cell tumour excisions are at greater risk of healing complications than wounds from complete excisions, or cutaneous histiocytomas. METHODS: Mast cell tumours and cutaneous histiocytomas submitted to Nationwide Laboratories between November 1, 2007 and April 30, 2008 were selected. Questionnaires were sent to submitting veterinarians requesting details of tumour characteristics, clinical approach to the tumour and wound healing. RESULTS: Three hundred and eighty-six mast cell tumours and 524 cutaneous histiocytomas were identified. One hundred and eighty-five mast cell tumours and 244 cutaneous histiocytomas questionnaires were returned (47% response). Wound complications arose in 20% of mast cell tumours and 21% of cutaneous histiocytomas. Multivariable analysis confirmed that larger tumours, tumours on the feet and a soft/"baggy" appearance, were significantly associated with a greater frequency of problems, leading to delayed wound healing and dehiscence. CLINICAL SIGNIFICANCE: Incomplete mast cell tumour excision does not lead to greater risk of wound complications. Mast cell tumour surgical wounds have a similar rate of wound complications as cutaneous histiocytoma wounds.


Assuntos
Doenças do Cão/patologia , Doenças do Cão/cirurgia , Histiocitoma Fibroso Maligno/veterinária , Mastocitose/veterinária , Complicações Pós-Operatórias/veterinária , Cicatrização , Animais , Doenças do Cão/epidemiologia , Cães , Feminino , Pé/patologia , Histiocitoma Fibroso Maligno/epidemiologia , Histiocitoma Fibroso Maligno/patologia , Histiocitoma Fibroso Maligno/cirurgia , Modelos Logísticos , Masculino , Mastocitose/epidemiologia , Mastocitose/patologia , Mastocitose/cirurgia , Complicações Pós-Operatórias/epidemiologia , Inquéritos e Questionários , Resultado do Tratamento , Reino Unido/epidemiologia
14.
Proc Natl Acad Sci U S A ; 104(9): 3663-6, 2007 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-17360699

RESUMO

La Isabela, the first European town in the New World, was established in 1494 by the second expedition of Christopher Columbus but was abandoned by 1498. The main motive for settlement was to find and exploit deposits of precious metals. Archaeological evidence of silver extraction at La Isabela seemed to indicate that the expedition had located and tested deposits of silver-bearing lead ore in the Caribbean. Lead isotope analysis refutes this hypothesis but provides new evidence of the desperation of the inhabitants of La Isabela just before its abandonment.


Assuntos
Chumbo/análise , Mineração/história , Prata , Sulfetos/análise , Arqueologia , História do Século XV , Humanos , Microscopia Eletrônica de Varredura , Índias Ocidentais
15.
Chem Res Toxicol ; 9(8): 1414-24, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8951247

RESUMO

High resolution 19F NMR spectroscopy has been used to investigate the kinetics of internal acyl migration and hydrolysis of the synthetic beta -1-O-acyl-D-glucopyranuronates of 2-, 3-, and 4-(trifluoromethyl) benzoic acids (TFMBAs) in phosphate buffer solutions at 30 degrees C as models of drug ester glucuronides. Apparent first-order degradation of the 1-O-acyl glucuronide and the sequential appearance of 2-, 3-, and 4-O-acyl isomers as both alpha- and beta-anomeric forms were observed for each TFMBA isomer. The overall degradation rate constants of the 2-, 3-, and 4-TFMBA 1-O-acyl isomers were 0.065 h-1, 0.25 h-1, and 0.52 h-1. In order to probe the reasons for these differences in reactivity, theoretical structural and electronic parameters for the beta-anomers of the 1-O-acyl glucuronides, their beta-2-O-acyl isomers, and both structures of the postulated ortho-acid ester intermediate were computed using semiempirical molecular orbital (AM1 and PM3) methods. The distinction between the slowly reacting 2-TFMBA glucuronide and the much faster reacting 3- and 4-TFMBA glucuronides could be observed by calculation of the relative bond order of the C-O bonds in the ortho-acid ester intermediates. The slow internal acyl migration rate of the 2-TFMBA isomer was also partly attributed to the high degree of steric hindrance of the trifluoromethyl group obstructing attack by the glucuronic acid 2-hydroxy group on the carbonyl carbon to form the ortho-acid ester intermediate. Some calculated molecular orbital properties, namely, dipole moment, energy of the lowest unoccupied molecular orbital (LUMO), LUMO density, and nucleophilic frontier density on the carbonyl carbon, were also shown to be related to the measured half-lives. This work gives insight into the molecular physicochemical properties that influence the acyl migration kinetics of simple model drug glucuronides and is of potential importance in understanding more complex drug glucuronide acyl migration reactions of toxicological interest.


Assuntos
Benzoatos/química , Espectroscopia de Ressonância Magnética , Polissacarídeos/química , Acilação , Soluções Tampão , Fenômenos Químicos , Físico-Química , Glucuronatos/química , Meia-Vida , Conformação Molecular , Ligação Proteica , Espectrometria de Massas de Bombardeamento Rápido de Átomos
16.
Med Leg J ; 45(3): 82-93, 1977.
Artigo em Inglês | MEDLINE | ID: mdl-607135
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