RESUMO
Platelet activation contributes to the alteration of endothelial function, a critical initial step in atherogenesis through the production and release of prooxidant mediators. There is uncertainty about the precise role of polyphenols in interaction between platelets and endothelial cells (ECs). We aimed to investigate whether polyphenols are able to reduce endothelial activation induced by activated platelets. First, we compared platelet activation and flow-mediated dilation (FMD) in 10 healthy subjects (HS) and 10 patients with peripheral artery disease (PAD). Then, we evaluated the effect of epicatechin plus catechin on platelet-HUVEC interaction by measuring soluble cell adhesion molecules (CAMs), NOx production, and eNOS phosphorylation (p-eNOS) in HUVEC. Compared to HS, PAD patients had enhanced platelet activation. Conversely, PAD patients had lower FMD than HS. Supernatant of activated platelets from PAD patients induced an increase of sCAMs release and a decrease of p-eNOS and nitric oxide (NO) bioavailability compared to unstimulated HUVEC. Coincubation of HUVEC, with supernatant of PAD platelets patients, pretreated with a scalar dose of the polyphenols, resulted in a decrease of sCAMs release and in an increase of p-eNOS and NO bioavailability. This study demonstrates that epicatechin plus catechin reduces endothelial activation induced by activated platelets.
Assuntos
Plaquetas/efeitos dos fármacos , Catequina/farmacologia , Doença Arterial Periférica/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Plaquetas/metabolismo , Moléculas de Adesão Celular/metabolismo , Estudos Transversais , Feminino , Células Endoteliais da Veia Umbilical Humana , Humanos , Masculino , Pessoa de Meia-Idade , Óxido Nítrico Sintase Tipo III/metabolismo , Óxidos de Nitrogênio/metabolismo , Doença Arterial Periférica/metabolismo , Doença Arterial Periférica/patologia , Fosforilação/efeitos dos fármacos , Ativação Plaquetária/efeitos dos fármacosRESUMO
Polymorphous low-grade adenocarcinoma (PLGA) is a rare, malignant salivary gland tumor, which is found almost exclusively in minor salivary glands, primarily those in the palate. We report a case of PLGA arising from minor salivary gland of the palate in a 63-year-old female patient. The tumor was resected through the oral cavity performing a bilateral maxillectomy and surgical defect was reconstructed using a free radial forearm flap combined with iliac crest bone graft. The patient was free of disease at 48 months follow-up. The histopathological features of PLGA, the importance of differential diagnosis from pleomorphic adenoma and adenoid cystic carcinoma and the type of reconstruction are discussed in this article.
Assuntos
Adenocarcinoma/patologia , Neoplasias Maxilares/patologia , Adenocarcinoma/cirurgia , Feminino , Humanos , Neoplasias Maxilares/cirurgia , Pessoa de Meia-Idade , Gradação de TumoresRESUMO
Haemangiomas are benign vascular neoplasms characterized by an abnormal proliferation of blood vessels. They may occur in any vascularized tissue including skin, subcutaneous tissue muscle and bone. These tumours are common in infancy and childhood and commonly involve subcutaneous or mucosal tissues. Intramuscular haemangiomas, a distinctive type of haemangioma occurring within skeletal muscle, account for less than 1% of all haemangiomas. They occur more often in trunk and extremity muscles, whereas involvement of the temporal muscle is extremely rare. Herein, the case is reported of a 38-year-old male who presented with a round, painless mass in the left temporal fossa, which was interpreted as an intramuscular haemangioma after a magnetic resonance imaging scan. In this report, clinico-pathological findings are described in an additional case of haemangioma involving the temporal muscle, and a review is made of the international literature on this subject.
Assuntos
Hemangioma Cavernoso/patologia , Hemangioma/patologia , Neoplasias Musculares/patologia , Músculo Temporal/patologia , Adulto , Hemangioma/complicações , Hemangioma Cavernoso/complicações , Humanos , Imageamento por Ressonância Magnética , Masculino , Neoplasias Musculares/complicaçõesRESUMO
Chondromyxoid fibroma is a rare benign tumour of chondral origin. It usually involves the long bones of the lower extremity, whilst involvement of craniofacial skeleton is extremely unusual. The second case of chondromyxoid fibroma of the zygoma described in literature is presented and the surgical resection of the lesion with tumour-free margins as the key factor for avoiding local recurrence of this tumour is emphasised.
Assuntos
Condroblastoma/diagnóstico , Neoplasias Cranianas/diagnóstico , Zigoma/patologia , Calcinose/patologia , Seguimentos , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
This report describes the first case of primary leiomyosarcoma of the submandibular salivary glands and emphasizes the role of immunohistochemical study for a correct diagnosis of this tumour. In line with results of international literature, we associated surgery with radiotherapy and 2 years postoperatively there was no sign of recurrence.
Assuntos
Leiomiossarcoma/patologia , Neoplasias da Glândula Submandibular/patologia , Humanos , Leiomiossarcoma/radioterapia , Leiomiossarcoma/cirurgia , Masculino , Pessoa de Meia-Idade , Radioterapia Adjuvante , Neoplasias da Glândula Submandibular/radioterapia , Neoplasias da Glândula Submandibular/cirurgiaRESUMO
The low affinity neurotrophin receptor (p75(NTR)) is implicated in promoting oligodendrocytic death after nerve growth factor (NGF) stimulation but NGF and neurotrophin-3 (NT-3) can also potentiate oligodendrocytic survival. We show regional variability in p75(NTR) expression within the central nervous system of the postnatal rat; expression is readily detectable by immunohistochemistry upon a subset of CNPase-positive oligodendroglia in optic nerve but not within the cerebrum. Nevertheless, oligodendroglia isolated from the cerebrum and cultured for 16 hours express p75(NTR) as well as the trkC but not the TrkA gene. Viability was not, however, influenced by exposure to either NGF or NT-3. Cells overexpressing p75(NTR) remained unresponsive to NGF but exhibited potentiated survival with NT-3, correlating with the differential expression profile of their high affinity receptors.
Assuntos
Córtex Cerebral/citologia , Oligodendroglia/fisiologia , Receptores de Fator de Crescimento Neural/genética , Adenoviridae/genética , Animais , Animais Recém-Nascidos , Células Cultivadas , Regulação da Expressão Gênica no Desenvolvimento , Vetores Genéticos , Imuno-Histoquímica , Óperon Lac , Oligodendroglia/química , Oligodendroglia/citologia , RNA Mensageiro/análise , Ratos , Ratos Wistar , Receptor de Fator de Crescimento Neural/análise , Receptor de Fator de Crescimento Neural/genética , Receptor trkA/genética , Receptor trkC/análise , Receptor trkC/genética , Receptores de Fator de Crescimento Neural/análiseRESUMO
Genistein is a naturally occurring isoflavone that interacts with estrogen receptors and multiple other molecular targets. Human exposure to genistein is predominantly through consumption of soy products, including soy-based infant formula and dietary supplements. A dose range-finding study was conducted as a prelude to a multigeneration bioassay to assess potential toxicities associated with genistein consumption. Genistein was administered in a soy- and alfalfa-free diet at 0, 5, 25, 100, 250, 625, or 1250 ppm to pregnant dams starting on Gestation day 7 and continuing throughout pregnancy. Dietary exposure of the dams continued through lactation, and pups were maintained on the same dosed feed as their mother after weaning until sacrifice at Postnatal day 50. Body weight and feed consumption of the treated dams prior to parturition showed a decreasing trend with a significant reduction at the highest dose. Litter birth weight was depressed in the 1250 ppm dose group, and pups of both sexes in that dose group had significantly decreased body weights relative to controls at the time of sacrifice. The most pronounced organ weight effects in the pups were decreased ventral prostate weight in males at the 1250 ppm dose and a trend toward higher pituitary gland to body weight ratios in both sexes. Histopathologic examination of female pups revealed ductal/alveolar hyperplasia of the mammary glands at 250 to 1250 ppm. Ductal/alveolar hyperplasia and hypertrophy also occurred in males, with significant effects seen at 25 ppm and above. Abnormal cellular maturation in the vagina was observed at 625 and 1250 ppm, and abnormal ovarian antral follicles were observed at 1250 ppm. In males, aberrant or delayed spermatogenesis in the seminiferous tubules relative to controls was observed at 1250 ppm. There was a deficit of sperm in the epididymis at 625 and 1250 ppm relative to controls, although testicular spermatid head counts and epididymal spermatozoa counts did not show significant differences from controls at these doses. Both sexes showed an increase in the incidence and/or severity of renal tubal mineralization at doses of 250 ppm and above. Dietary genistein thus produced effects in multiple estrogen-sensitive tissues in males and females that are generally consistent with its estrogenic activity. These effects occurred within exposure ranges achievable in humans.
Assuntos
Moduladores de Receptor Estrogênico/toxicidade , Genisteína/toxicidade , Reprodução/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Dieta , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Moduladores de Receptor Estrogênico/administração & dosagem , Feminino , Genisteína/administração & dosagem , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/patologia , Masculino , Glândulas Mamárias Animais/efeitos dos fármacos , Glândulas Mamárias Animais/patologia , Nefrocalcinose/induzido quimicamente , Nefrocalcinose/patologia , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Próstata/efeitos dos fármacos , Próstata/patologia , Ratos , Ratos Sprague-Dawley , Testes de ToxicidadeRESUMO
We recently reported that nitrotyrosine and acetaminophen (APAP)-cysteine protein adducts colocalize in the hepatic centrilobular cells following a toxic dose of APAP to mice. Whereas APAP-adducts are formed by reaction of the metabolite N-acetyl-p-benzoquinone imine with cysteine, nitrotyrosine residues are formed by reaction of tyrosine with peroxynitrite. Peroxynitrite is formed from nitric oxide (NO) and superoxide. This manuscript examines APAP (300 mg/kg) hepatotoxicity in mice lacking inducible nitric oxide synthase activity (NOS2 null or knockout mice; C57BL/6-Nos2(tm1Lau)) and in the wildtype mice. In a time course the ALT levels in the exposed NOS2 null mice were approximately 50% of the wildtype mice; however, histological examination of liver sections indicated similar levels of centrilobular hepatic necrosis in both wild-type and NOS2 null mice. Serum nitrate plus nitrite levels (NO synthesis) were identical in saline-treated NOS2 null and wild-type mice (53 +/- 2 microM). APAP increased NO synthesis in wild-type mice only. The increases paralleled the increases in ALT levels with peak levels of serum nitrate plus nitrite at 6 h (168 +/- 27 microM). In wild-type mice hepatic tyrosine nitration was greatly increased relative to saline treated controls. Tyrosine nitration increased in NOS2 null mice also, but the increase was much less. APAP increased hepatic malonaldehyde levels (lipid peroxidation) in NOS2 null mice only. The results suggest the presence of multiple pathways to APAP-mediated hepatic necrosis, one via nitrotyrosine, as in the wild-type mice, and another that is not dependent upon inducible nitric oxide synthase activity, but which may involve increased superoxide.
Assuntos
Acetaminofen/toxicidade , Analgésicos não Narcóticos/toxicidade , Fígado/efeitos dos fármacos , Óxido Nítrico Sintase/deficiência , Tirosina/análogos & derivados , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Deleção de Genes , Técnicas Imunoenzimáticas , Peroxidação de Lipídeos , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Nitratos/metabolismo , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo II , Nitritos/metabolismo , Tirosina/metabolismoRESUMO
The carcinogenicity of fumonisin B1 (FB1), a worldwide contaminant of corn produced by Fusaria species of fungi, has been tested recently in 2-year feeding studies in Fischer F344 rats and B6C3F1 mice. Inclusion of FB1 at 50 and 80 ppm in the diet induced liver tumors in female mice, and at 50 and 150 ppm induced renal tumors in male rats (22). In the present study, the kidneys from the rat bioassay were examined to characterize the various histopathological changes associated with renal tumor induction. In all high-dose (150 ppm) and mid-dose (50 ppm) male rats, and to a lesser extent in high-dose (100 ppm) female rats, there was evidence of sustained nephrotoxicity manifested as basophilia, apoptosis, cell regeneration, and simple tubule hyperplasia, affecting proximal convoluted tubules in the deep cortex, extending into the outer region of the outer stripe of outer medulla. A further alteration consisted of sporadic areas of interstitial hyalinization in deep cortex, suggestive of expanded basement membrane, coupled with tubule atrophy. The continued presence of nephrotoxicity throughout chronic exposure to FB1 suggested that renal tumor development may have been an outcome of sustained cell loss and compensatory regeneration. In some cases, preneoplastic tubules or incipient renal tumors presented an immature or fetal form in association with interstitial hyalinization. The renal tubule tumors induced by FB1 were typified by a rare, highly malignant, anaplastic variant capable of growth by infiltration. Of the 10 renal tubule tumors diagnosed in the mid-dose males, and the 16 in the high-dose males, 8 and 10, respectively, were graded as carcinomas. Anaplastic variants represented 50% of the mid-dose carcinomas and 80% of the high-dose carcinomas. One of the anaplastic carcinomas in a mid-dose male was a true sarcomatoid phenotype not previously recorded in the rodent. Metastatic invasion of the lung occurred with 25% of the mid-dose carcinomas and 50% of the high-dose carcinomas. It was speculated that FB1 may have been influencing the growth characteristics of the induced renal tumors via its inhibitory action on the synthesis of sphingolipids, which in turn, participate in regulating cell contact, growth, and differentiation, or alternatively by affecting cell adhesion molecules.
Assuntos
Adenoma/induzido quimicamente , Ácidos Carboxílicos/toxicidade , Carcinógenos Ambientais/toxicidade , Carcinoma/induzido quimicamente , Fumonisinas , Neoplasias Renais/induzido quimicamente , Túbulos Renais Proximais/patologia , Micotoxinas/toxicidade , Adenoma/patologia , Animais , Ácidos Carboxílicos/administração & dosagem , Testes de Carcinogenicidade , Carcinógenos Ambientais/administração & dosagem , Carcinoma/secundário , Dieta , Relação Dose-Resposta a Droga , Feminino , Hiperplasia/induzido quimicamente , Hiperplasia/patologia , Neoplasias Renais/patologia , Masculino , Micotoxinas/administração & dosagem , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/patologia , Ratos , Ratos Endogâmicos F344RESUMO
Previously we have shown that hepatotoxicity of thioacetamide (TA) was increased in streptozotocin (STZ)-induced diabetic (DB) rats due to combined effects of enhanced bioactivation-based liver injury of TA and compromised liver tissue repair response. We have also shown that TA is primarily bioactivated by hepatic CYP2E1. The present study was done to further investigate the importance of liver tissue repair in determining the final outcome of hepatotoxicity. STZ-induced DB rats were pretreated with a CYP2E1 inhibitor, diallyl sulfide (DAS), to decrease the bioactivation-based liver injury of TA. The treatments were as follows: DB/DAS/TA, DB/corn oil/TA, and DB/DAS/saline. Nondiabetic (non-DB) rats received the same treatments as controls. A dose of TA (300 mg/kg ip), which was nonlethal in non-DB rats, caused 92 and 90% mortality in DB/DAS/TA and DB/corn oil/TA groups, respectively. At various times (0--60 h) after treatment, liver injury was assessed by plasma alanine aminotransferase and histopathology. Cell proliferation was evaluated by [(3)H]thymidine incorporation and immunohistochemical staining of proliferating cell nuclear antigen (PCNA). In the DB/DAS/TA rats, DAS pretreatment markedly reduced the CYP2E1-dependent liver injury of TA compared to that in DB/corn oil/TA rats. However, subsequent hepatic DNA synthesis in both DB groups was inhibited approximately 50%. PCNA analysis showed a corresponding decrease in cell-cycle progression. This compromised tissue repair response in DB rats was insufficient to compensate for cell loss, resulting in progression of liver injury and culminating in high mortality in both DB groups. Furthermore, non-DB rats were pretreated with a CYP2E1 inducer, isoniazid, to increase the bioactivation-based TA liver injury equal to the liver injury observed in DB/DAS/TA rats. Despite equal injury up to 36 h following TA treatment, the tissue repair response in the non-DB rats was highly stimulated to compensate for liver injury and led to 70% survival in this group. These studies underscore the importance of adequate and timely tissue repair in compensating for liver injury and protecting from lethality.
Assuntos
Compostos Alílicos/farmacologia , Doença Hepática Induzida por Substâncias e Drogas , Inibidores do Citocromo P-450 CYP2E1 , Diabetes Mellitus Experimental/complicações , Inibidores Enzimáticos/farmacologia , Sulfetos/farmacologia , Tioacetamida/toxicidade , Alanina Transaminase/sangue , Animais , Divisão Celular , DNA/biossíntese , Imuno-Histoquímica , Fígado/patologia , Hepatopatias/mortalidade , Hepatopatias/patologia , Masculino , Antígeno Nuclear de Célula em Proliferação/análise , Ratos , Ratos Sprague-DawleyRESUMO
Fumonisin B1 (FB1) is a mycotoxin isolated from Fusarium fungi that contaminate crops worldwide. A previous study demonstrated that FB1 promoted preneoplastic foci in initiated rats and induced hepatocellular carcinomas in BD IX rats at 50 parts per million (ppm), but fundamental dose-response data were not available to assist in setting regulatory guidelines for this mycotoxin. To provide this information, female and male F344/N/Nctr BR rats and B6C3F1 Nctr BR mice were fed for two years a powdered NIH-31 diet containing the following concentrations of FB1: female rats, 0, 5, 15, 50, and 100 ppm; male rats, 0, 5, 15, 50, and 150 ppm; female mice, 0, 5, 15, 50, and 80 ppm; male mice, 0, 5, 15, 80, and 150 ppm. FB1 was not tumorigenic in female F344 rats with doses as high as 100 ppm. Including FB1 in the diets of male rats induced renal tubule adenomas and carcinomas in 0/48, 0/40, 9/48, and 15/48 rats at 0, 5, 15, 50, and 150 ppm, respectively. Including up to 150 ppm FB1 in the diet of male mice did not affect tumor incidence. Hepatocellular adenomas and carcinomas were induced by FB1 in the female mice, occurring in 5/47, 3/48, 1/48, 19/47, and 39/45 female mice that consumed diets containing 0, 5, 15, 50, and 80 ppm FB1, respectively. This study demonstrates that FB1 is a rodent carcinogen that induces renal tubule tumors in male F344 rats and hepatic tumors in female B6C3F1 mice.
Assuntos
Ácidos Carboxílicos/toxicidade , Carcinógenos Ambientais/toxicidade , Fumonisinas , Neoplasias Renais/induzido quimicamente , Neoplasias Hepáticas Experimentais/induzido quimicamente , Micotoxinas/toxicidade , Ração Animal/efeitos adversos , Animais , Bioensaio , Peso Corporal/efeitos dos fármacos , Ácidos Carboxílicos/administração & dosagem , Carcinógenos Ambientais/administração & dosagem , Relação Dose-Resposta a Droga , Feminino , Fusarium , Rim/citologia , Rim/efeitos dos fármacos , Neoplasias Renais/patologia , Túbulos Renais/citologia , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/fisiopatologia , Fígado/citologia , Fígado/efeitos dos fármacos , Fígado/fisiopatologia , Neoplasias Hepáticas Experimentais/patologia , Masculino , Camundongos , Camundongos Endogâmicos , Micotoxinas/administração & dosagem , Ratos , Ratos Endogâmicos F344 , Análise de SobrevidaRESUMO
Fumonisin B1(FB1) is a fungal metabolite of Fusarium verticillioides (= F. moniliforme), a fungus that grows on many crops worldwide. Previous studies demonstrated that male BD IX rats consuming diets containing 50 ppm fumonisin B1 developed hepatocellular carcinomas. In our recent studies, diets containing FB1 at 50 ppm or higher concentrations induced renal tubule carcinomas in male F344/N/Nctr BR rats and hepatocellular carcinomas in female B6C3F1/Nctr BR mice. The carcinogenicity of FB1 in rats and mice is not due to DNA damage, as several laboratories have demonstrated that FB1 is not a genotoxin. FB1 induces apoptosis in cells in vitro. Including FB1 in the diets of rats results in increased hepatocellular and renal tubule epithelial cell apoptosis. In studies with F344/N/Nctr BR rats consuming diets containing up to 484 ppm FB1 for 28 days, female rats demonstrated more sensitivity than male rats in the induction of hepatocellular apoptosis and mitosis. Conversely, induction of renal tubule apoptosis and regeneration were more pronounced in male than in female rats. Induction of renal tubule apoptosis and hyperplasia correlated with the incidence of renal tubule carcinomas that developed in the 2-year feeding study with FB1 in the F344/N/Nctr BR rats. The data are consistent with the hypothesis that the induction of renal tubule carcinomas in male rats could be partly due to the continuous compensatory regeneration of renal tubule epithelial cells in response to the induction of apoptosis by fumonisin B1.
Assuntos
Ácidos Carboxílicos/toxicidade , Carcinógenos Ambientais/toxicidade , Fumonisinas , Neoplasias Renais/induzido quimicamente , Rim/efeitos dos fármacos , Neoplasias Hepáticas Experimentais/induzido quimicamente , Micotoxinas/toxicidade , Regeneração/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Bioensaio , Sobrevivência Celular , Epitélio/efeitos dos fármacos , Epitélio/fisiopatologia , Feminino , Hepatócitos/efeitos dos fármacos , Rim/fisiologia , Neoplasias Renais/fisiopatologia , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/fisiopatologia , Neoplasias Hepáticas Experimentais/fisiopatologia , Masculino , Mitose/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Endogâmicos F344RESUMO
Reperfusion injury can cause liver dysfunction after cold storage and warm ischemia. Recently it has been suggested that more than 50% of hepatocytes and sinusoidal endothelial cells (SEC) are undergoing apoptosis during the first 24 hours of reperfusion. The aim of our study was to quantify apoptotic and necrotic hepatocytes and apoptotic SEC after 60 or 120 minutes of warm, partial no-flow ischemia and 0 to 24 hours reperfusion in male SD rats. Apoptotic cells were identified by TUNEL assay in combination with morphological criteria. After 60 minutes of ischemia and 1 hour of reperfusion there was a significant increase of apoptotic hepatocytes (0.7 +/- 0.1% vs. 0.3 +/- 0.1% in controls) and SEC (1.5 +/- 0.6% vs. 0.3 +/- 0.1% in controls). The number of apoptotic SEC and hepatocytes was not different from controls at 6 hours or 24 hours of reperfusion. In contrast, the number of necrotic hepatocytes was quantified as 12 +/- 2% at 1 hour, 34 +/- 6% at 6 hours, and 57 +/- 11% at 24 hours. These results correlated with the increase in plasma ALT levels at these time points. Longer (120 min) ischemia times did not affect the number of apoptotic cells but increased hepatocellular necrosis to 58 +/- 4% at 6 hours reperfusion. No significant increase in caspase-3 activity and processing was detectable in any of these livers. Moreover, the caspase inhibitor Z-Asp-cmk (2 mg/kg IV) had no significant effect on reperfusion injury. Our results suggest that only a small minority of SEC and hepatocytes undergo apoptosis after 60 to 120 minutes of warm ischemia followed by 0 to 24 hours of reperfusion. Oncotic necrosis appears to be the principal mechanism of cell death for both cell types.
Assuntos
Temperatura Alta , Isquemia/fisiopatologia , Circulação Hepática , Fígado/fisiopatologia , Traumatismo por Reperfusão/fisiopatologia , Alanina Transaminase/sangue , Animais , Apoptose , Caspase 3 , Caspases/metabolismo , Contagem de Células , Morte Celular/fisiologia , Endotélio Vascular/patologia , Endotélio Vascular/fisiopatologia , Isquemia/patologia , Fígado/patologia , Necrose , Ratos , Traumatismo por Reperfusão/patologia , Fatores de TempoRESUMO
Diabetes is known to potentiate thioacetamide (TA)-induced liver injury via enhanced bioactivation. Little attention has been given to the role of compensatory tissue repair on ultimate outcome of hepatic injury in diabetes. The objective of this study was to investigate the effect of diabetes on TA-induced liver injury and lethality and to investigate the underlying mechanisms. We hypothesized that hepatotoxicity of TA in diabetic rats would increase due to enhanced bioactivation-mediated liver injury and also due to compromised compensatory tissue repair, consequently making a nonlethal dose of TA lethal. On day 0, male Sprague-Dawley rats (250-300 g) were injected with streptozotocin (STZ, 60 mg/kg ip) to induce diabetes. On day 10 the STZ-induced diabetic rats and the nondiabetic rats received a single dose of TA (300 mg/kg ip). This normally nonlethal dose of TA caused 90% mortality in the STZ-induced diabetic rats. At various times (0-60 h) after TA administration, liver injury was assessed by plasma alanine aminotransferase (ALT), sorbitol dehydrogenase (SDH), and liver histopathology. Liver function was evaluated by plasma bilirubin. Cell proliferation and tissue repair were evaluated by [(3)H]thymidine ((3)H-T) incorporation and proliferating cell nuclear antigen (PCNA) assays. In the nondiabetic rat, liver necrosis peaked at 24 h and declined thereafter toward normal by 60 h. In the STZ-induced diabetic rat, however, liver necrosis was significantly increased from 12 h onward and progressed, culminating in liver failure and death. Liver tissue repair studies showed that, in the liver of nondiabetic rats, S-phase DNA synthesis was increased at 36 h and peaked at 48 h following TA administration. However, DNA synthesis was approximately 50% inhibited in the liver of diabetic rats. PCNA study showed a corresponding decrease of cell-cycle progression, indicating that the compensatory tissue repair was sluggish in the diabetic rats. Further investigation of tissue repair by employing equitoxic doses (300 mg TA/kg in the non-diabetic rats; 30 mg TA/kg in the diabetic rats) revealed that, despite equal injury up to 24 h following injection, the tissue repair response in the diabetic rats was much delayed. The compromised tissue repair prolonged liver injury in the diabetic rats. These studies suggest that the increased TA hepatotoxicity in the diabetic rat is due to combined effects of increased bioactivation-mediated liver injury of TA and compromised compensatory tissue repair.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas/etiologia , Diabetes Mellitus Experimental/complicações , Regeneração Hepática/efeitos dos fármacos , Fígado/efeitos dos fármacos , Tioacetamida/toxicidade , Alanina Transaminase/sangue , Animais , Bilirrubina/sangue , Doença Hepática Induzida por Substâncias e Drogas/sangue , Doença Hepática Induzida por Substâncias e Drogas/patologia , DNA/biossíntese , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/patologia , Sinergismo Farmacológico , L-Iditol 2-Desidrogenase/sangue , Fígado/patologia , Masculino , Necrose , Antígeno Nuclear de Célula em Proliferação/metabolismo , Ratos , Ratos Sprague-Dawley , Taxa de Sobrevida , Timidina/metabolismo , Fatores de TempoRESUMO
Schwann cells express the low-affinity neurotrophin receptor (p75), but no role for either the neurotrophins or their cognate receptors in Schwann cell development has been established. We have found that Schwann cells isolated from postnatal day 1 (P1) or P2 mice that were p75-deficient exhibited potentiated survival compared to wild-type cells after growth factor and serum withdrawal. There was, however, no disparity in the survival of p75-deficient and wild-type Schwann cells isolated at embryonic day 15, suggesting that the death-inducing effects of p75 are developmentally regulated. A comparable degree of cell death was also observed in the sciatic nerves of both wild-type and p75-deficient mice at P1. However, 24 hr after axotomy, there was a 13-fold increase in the percentage of apoptotic nuclei in the distal nerve stumps of the transected sciatic nerves of neonatal wild-type but not p75-deficient mice. The expression of both the p75 and nerve growth factor (NGF) genes was upregulated after axotomy in neonatal wild-type nerves. Collectively, these results suggest that NGF-mediated activation of p75 is likely to be an important mediator of Schwann cell apoptosis in the context of peripheral nerve injury.
Assuntos
Apoptose/fisiologia , Receptor de Fator de Crescimento Neural/genética , Receptor de Fator de Crescimento Neural/metabolismo , Células de Schwann/citologia , Nervo Isquiático/fisiologia , Fatores Etários , Animais , Axotomia , Células Cultivadas , Regulação da Expressão Gênica no Desenvolvimento , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Fator de Crescimento Neural/genética , Fator de Crescimento Neural/metabolismo , Doenças do Sistema Nervoso Periférico/genética , Doenças do Sistema Nervoso Periférico/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Nervo Isquiático/citologiaRESUMO
In this study, the rodent air pouch model was used to examine the production and processing of oxidative DNA damage in two strains of rats commonly used in toxicity testing. An inflammatory response was induced by injecting zymosan A (50 mg) into an air pouch on male CD (Sprague-Dawley [S-D]) and Fisher 344 (F-344) rats, and the animals were then sacrificed at 1, 3, 7, 14, and 28 days (n = 6 per time point per strain). Tissues from the lining of the air pouch were collected for 8-hydroxy-2'-deoxyguanosine (8-OH-dG) analysis and for paraffin embedding. Significant (P < 0.01) increases in 8-OH-dG were observed after 1 day in the DNA from cells lining the air pouch of zymosan A-treated versus control S-D (101.5 +/- 27.1 vs. 23.1 +/- 2. 7 8-OH-dG/dG x 10(5)) and F-344 (51.4 +/- 5.3 vs. 14.4 +/- 0.6 8-OH-dG/dG x 10(5)) rats. By 28 days, 8-OH-dG levels had returned to background in S-D rats, but remained elevated in F-344 rats. The frequency of apoptosis was evaluated using the in situ end-labeling (TUNEL) assay, which revealed that zymosan A-treated S-D rats had a significantly (P < 0.05) higher frequency of apoptosis compared to zymosan A-treated F-344 rats. To examine the potential consequences of these differences in endogenously produced DNA damage and apoptosis, we measured mutations at the hprt locus in fibroblasts of the pouch lining and observed a significant (P < 0.05) increase in the mutant frequency at day 28 in F-344 rats (54.2 +/- 13.6 mutants per 10(6) cells) compared to controls (4.5 +/- 2.0 mutants per 10(6) cells). The mutant frequency was not increased in S-D rats. These data demonstrate that strain differences in the production and processing of oxidative DNA damage due to an inflammatory response may impact the long-term pathologic consequences of chronic inflammation. Environ. Mol. Mutagen. 35:336-342, 2000 Published 2000 Wiley-Liss, Inc.
Assuntos
Inflamação/induzido quimicamente , Mutação , Estresse Oxidativo , Animais , Cromatografia Líquida de Alta Pressão , Eletroquímica , Hipoxantina Fosforribosiltransferase/genética , Marcação In Situ das Extremidades Cortadas , Inflamação/metabolismo , Masculino , Ratos , Ratos Endogâmicos F344 , Ratos Sprague-Dawley , Especificidade da EspécieRESUMO
Upregulated expression of the low-affinity neurotrophin receptor (p75) in the central nervous system (CNS) during experimental autoimmune encephalomyelitis (EAE) has recently been demonstrated. To investigate whether p75 plays a role in disease pathogenesis, we adopted a gene therapy approach, utilizing antisense oligonucleotides to downregulate p75 expression during EAE. Phosphorothioate antisense oligonucleotides (AS), nonsense oligonucleotides (NS) or phosphate buffered saline (PBS) were injected daily for 18 days after immunization of SJL/J (H-2s)-mice with myelin proteolipid protein (PLP) peptide 139-151. In the AS group, there was a statistically significant reduction in both the mean maximal disease score (1.85 in the AS, 2.94 in the NS and 2.75 in the PBS-groups, respectively, P < 0.025) and in the cumulative disease incidence ( approximately 60% in the AS group and approximately 90% in the control groups). Histological and immunohistochemical analysis showed reduced inflammation and demyelination, as well as reduced p75 expression at the blood-brain barrier (BBB) in the AS-treated mice in comparison with both control groups. There was no difference, however, in p75 expression on neural cells within the CNS between the three groups of mice. We conclude that p75 could play a proactive role in the pathogenesis of EAE and may exert its effect at the level of the BBB.
Assuntos
Encefalomielite Autoimune Experimental/terapia , Terapia Genética , Oligonucleotídeos Antissenso/farmacologia , Receptor de Fator de Crescimento Neural/genética , Animais , Divisão Celular/fisiologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/patologia , Progressão da Doença , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/fisiopatologia , Camundongos , Camundongos Endogâmicos , Receptor de Fator de Crescimento Neural/metabolismo , Baço/citologia , Baço/metabolismo , Resultado do TratamentoRESUMO
Oligodendrocytes, the myelinating cells of the central nervous system, arise from a profilerating pool of motile progenitor cells. The proliferation and survival of these cells is dependent on signal transduction via several protein tyrosine kinases (PTKs) including receptors for fibroblast growth factor -2, the platelet-derived growth factor receptors and the neurotrophin receptor, trkC. We hypothesized that additional PTKs could also influence oligodendroglial development. Utilizing RTPCR, we amplified from post-natal day 6 rat oligodendroglia 17 distinct kinase domain sequences, 14 of which were not previously known to be expressed by oligodendroglia. Amongst the sequences identified were the c-met and Fak genes, whose protein products regulate the motility of other epithelial cell types. Utilizing immunohistochemistry, we confirmed that both c-met and Fak are expressed by cultured oligodendroglia, suggesting that these proteins could also be implicated in regulating the motility of these cells.
Assuntos
Moléculas de Adesão Celular/genética , Movimento Celular/genética , Células Epiteliais/metabolismo , Oligodendroglia/metabolismo , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas c-met/genética , Animais , Animais Recém-Nascidos , Técnicas de Cultura de Células , Quinase 1 de Adesão Focal , Proteína-Tirosina Quinases de Adesão Focal , Fator de Crescimento de Hepatócito/metabolismo , RNA Mensageiro/análise , Ratos , Ratos Sprague-Dawley , Células-Tronco/metabolismoRESUMO
The rodenticide alpha-naphthylthiourea (ANTU) causes pulmonary edema and pleural effusion that leads to death via pulmonary insufficiency. Rats become resistant to the lethal effect of ANTU if they are first exposed to a small, nonlethal dose of ANTU. Young rats are also resistant to ANTU. The mechanism by which rats develop resistance by a prior, small dose exposure has yet to be determined. Growth factor induced-pulmonary hyperplasia has been demonstrated to attenuate ANTU-induced lung leak. We hypothesized that a small dose of ANTU protects against a large dose through pulmonary cell hyperplasia induced by the protective dose. Furthermore, we hypothesized that this hyperplasia is associated with altered transcription of growth factors. Male Sprague-Dawley rats (175-225 g) were treated with a low dose of ANTU (5 mg ANTU/kg; ANTU(L)) 24 h before challenge with a 100% lethal dose of ANTU (70 mg ANTU/kg; ANTU(H)) resulting in 100% protection against the lethal effect of ANTU(H). ANTU(L) protection against ANTU(H) lasted for 5 days, slowly phased out, all being lost by day 20. Injury was assessed by estimating pulmonary vascular permeability and through histopathological examination. ANTU(H) alone resulted in an increase in pulmonary edema leading to animal death. However, injury was prevented if the rats were first treated with ANTU(L). There was a stimulation of pulmonary cell hyperplasia in the lungs of ANTU(L) treated rats as measured by [3H]-thymidine and bromodeoxyuridine incorporation. Treatment with the antimitotic agent colchicine abolished ANTU(L)-induced resistance to ANTU(H). ANTU resistant rats were also resistant to the lethal effect of paraquat. Paraquat is not taken up by pneumocytes if they are undergoing hyperplasia. ANTU(L) administration resulted in an up regulation of gene transcription for keratinocyte growth factor, transforming growth factor-beta, keratinocyte growth factor receptor and epidermal growth factor receptor as determined through reverse transcription-polymerase chain reaction. A significant increase in transforming growth factor-alpha was not observed. These findings collectively suggest that ANTU(L)-induced pulmonary cell hyperplasia underlies resistance to ANTU(H). Furthermore, the stimulation of hyperplasia may be due to altered growth factor and growth factor receptor expressions.