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1.
Cell Death Dis ; 5: e1048, 2014 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-24503540

RESUMO

miRNA let-7e is involved in stem cell differentiation, and metalloproteinases are among its potential target genes. We hypothesized that the inhibitory action of let-7e on regulation of MMP9 expression could represent a crucial mechanism during differentiation of adipose-derived stem cells (ASCs). ASCs were differentiated with all-trans retinoic acid (ATRA) to promote differentiation, and the effect of let-7 silencing during differentiation was tested. Results indicate that ASCs cultured with ATRA differentiated into cells of the epithelial lineage. We found that ASCs cultured with ATRA or transfected with miRNA let-7e expressed epithelial markers such as cytokeratin-18 and early renal organogenesis markers such as Pax2, Wt1, Wnt4 and megalin. Conversely, the specific knockdown of miRNA let-7e in ASCs significantly decreased the expression of these genes, indicating its vital role during the differentiation process. Using luciferase reporter assays, we also showed that MMP9 is a direct target of miRNA let-7e. Thus, our results suggest that miRNA let-7e acts as a matrix metalloproteinase-9 (MMP9) inhibitor and differentiation inducer in ASCs.


Assuntos
Adipócitos/citologia , Adipócitos/enzimologia , Adipogenia , Metaloproteinase 9 da Matriz/genética , Células-Tronco/citologia , Animais , Células Cultivadas , Humanos , Queratina-18/genética , Queratina-18/metabolismo , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Células-Tronco/enzimologia
2.
Cell Death Dis ; 3: e279, 2012 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-22402603

RESUMO

Injury due to cold ischemia reperfusion (I/R) is a major cause of primary graft non-function following liver transplantation. We postulated that I/R-induced cellular damage during liver transplantation might affect the secretory pathway, particularly at the endoplasmic reticulum (ER). We examined the involvement of ER stress in organ preservation, and compared cold storage in University of Wisconsin (UW) solution and in Institute Georges Lopez-1 (IGL-1) solution. In one group of rats, livers were preserved in UW solution for 8 h at 4 °C, and then orthotopic liver transplantation was performed according to Kamada's cuff technique. In another group, livers were preserved in IGL-1 solution. The effect of each preservation solution on the induction of ER stress, hepatic injury, mitochondrial damage and cell death was evaluated. As expected, we found increased ER stress after liver transplantation. IGL-1 solution significantly attenuated ER damage by reducing the activation of three pathways of unfolded protein response and their effector molecules caspase-12, C/EBP homologous protein-10, X-box-binding protein 1, tumor necrosis factor-associated factor 2 and eukaryotic translation initiation factor 2. This attenuation of ER stress was associated with a reduction in hepatic injury and cell death. Our results show that IGL-1 solution may be a useful means to circumvent excessive ER stress reactions associated with liver transplantation, and may optimize graft quality.


Assuntos
Transplante de Fígado , Fígado/metabolismo , Soluções para Preservação de Órgãos/farmacologia , Preservação de Órgãos/métodos , Transdução de Sinais/efeitos dos fármacos , Adenosina/farmacologia , Alopurinol/farmacologia , Animais , Apoptose/efeitos dos fármacos , Caspase 12/genética , Caspase 12/metabolismo , Isquemia Fria , Temperatura Baixa , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Glutationa/farmacologia , Insulina/farmacologia , Fígado/patologia , Masculino , Rafinose/farmacologia , Ratos , Fatores de Transcrição de Fator Regulador X , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/prevenção & controle , Transdução de Sinais/genética , Fator 2 Associado a Receptor de TNF/genética , Fator 2 Associado a Receptor de TNF/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Resposta a Proteínas não Dobradas/genética
3.
N Z Vet J ; 60(1): 21-6, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22175425

RESUMO

AIMS: To study the occurrence and spatial distribution of Shiga toxin-producing Escherichia coli (STEC) O157 in calves less than 1-week-old (bobby calves) born on dairy farms in the North Island of New Zealand, and to determine the association of concentration of IgG in serum, carcass weight, gender and breed with occurrence of E. coli O157 in these calves. METHODS: In total, 309 recto-anal mucosal swabs and blood samples were collected from bobby calves at two slaughter plants in the North Island of New Zealand. The address of the farm, tag number, carcass weight, gender and breed of the sampled animals were recorded. Swabs were tested for the presence of E. coli O157 using real time PCR (RT-PCR). All the farms were mapped geographically to determine the spatial distribution of farms positive for E. coli O157. K function analysis was used to test for clustering of these farms. Multiplex PCR was used for the detection of Shiga toxin 1 (stx1), Shiga toxin 2 (stx2), E. coli attaching and effacing (eae) and Enterohaemolysin (ehxA) genes in E. coli O157 isolates. Genotypes of isolates from this study (n = 10) along with human (n = 18) and bovine isolates (n = 4) obtained elsewhere were determined using bacteriophage insertion typing for stx encoding. RESULTS: Of the 309 samples, 55 (17.7%) were positive for E. coli O157 by RT-PCR and originated from 47/197 (23.8%) farms. E. coli O157 was isolated from 10 samples of which seven isolates were positive for stx2, eae and ehxA genes and the other three isolates were positive for stx1, stx2, eae and ehxA. Bacteriophage insertion typing for stx encoding revealed that 12/18 (67%) human and 13/14 (93%) bovine isolates belonged to genotypes 1 and 3. K function analysis showed some clustering of farms positive for E. coli O157. There was no association between concentration of IgG in serum, carcass weight and gender of the calves, and samples positive for E. coli O157, assessed using linear mixed-effects models. However, Jersey calves were less likely to be positive for E. coli O157 by RT-PCR than Friesian calves (p = 0.055). CONCLUSIONS: Healthy bobby calves are an asymptomatic reservoir of E. coli O157 in New Zealand and may represent an important source of infection for humans. Carriage was not associated with concentration of IgG in serum, carcass weight or gender.


Assuntos
Doenças dos Bovinos/microbiologia , Escherichia coli O157/isolamento & purificação , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Animais Recém-Nascidos , Bovinos , Doenças dos Bovinos/epidemiologia , Imunoglobulina G/sangue , Nova Zelândia/epidemiologia
4.
Vet Microbiol ; 151(1-2): 99-103, 2011 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-21420259

RESUMO

Bovine tuberculosis costs New Zealand more than $80 million per year, mostly because extensive areas of the country are occupied by brushtail possums infected with Mycobacterium bovis. AgResearch has a major programme to produce new live tuberculosis vaccines that can be delivered to possums. Primary work involved development of molecular biological methods to enable genetic manipulation of M. bovis, including the production of random and specific mutants. Many avirulent mutants of M. bovis have been produced and their vaccine efficacy has been compared to BCG in guinea pigs. Selected mutants that perform at least as well as BCG are retested in guinea pigs using an extended vaccination protocol in which animals are pre-sensitized to environmental mycobacteria to mimic natural exposure. Ten candidate vaccines that have induced good protection in guinea pigs have been subsequently tested as vaccines in possums. While the protective efficacy of an M. bovis mutant inoculated into guinea pigs reliably indicated that some protection would be induced in possums, the most protective mutant in guinea pigs was different from that in possums. This illustrates the importance of testing in the target species as part of new vaccine development. An important outcome of this work was the identification of an operon in M. bovis whose inactivation produced an avirulent M. bovis vaccine candidate that was better than BCG in protecting possums from experimental tuberculosis. Allelic exchange methods are now being used to produce vaccine strains with multiple specific mutations to improve safety and immunological characteristics.


Assuntos
Mycobacterium bovis/genética , Trichosurus/microbiologia , Vacinas contra a Tuberculose/imunologia , Tuberculose Bovina/prevenção & controle , Animais , Bovinos , Cobaias , Mutação , Mycobacterium bovis/imunologia , Nova Zelândia , Vacinas contra a Tuberculose/administração & dosagem , Tuberculose Bovina/imunologia , Vacinação/veterinária , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia
5.
Epidemiol Infect ; 138(7): 992-1003, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19883521

RESUMO

Campylobacter jejuni is a leading cause of human bacterial gastroenteritis throughout the industrialized world. We investigated whether or not differences in gene complement at the lipooligosaccharide (LOS) biosynthesis locus can identify epidemiologically useful binary genomotypes in 87 C. jejuni isolates from poultry-associated multilocus sequence types (STs) collected during the course of a sentinel surveillance study. Using a PCR-based approach, we correlated assignment of both isolate LOS locus class and binary genomotype with ST. We found that isolates within STs 45, 190, 354 and 474 displayed mosaicism in gene complement at the intra-ST level. For example, based upon their binary genomotypes, we assigned individual ST-45 isolates from human clinical cases as probably originating from either a poultry or wild-bird source. However, intra-ST mosaicism in gene complement was observed alongside broader patterns of congruence in LOS locus class and gene complement that distinguished between isolates from different STs.


Assuntos
Técnicas de Tipagem Bacteriana/métodos , Campylobacter jejuni/classificação , Lipopolissacarídeos/biossíntese , Animais , Campylobacter jejuni/genética , Campylobacter jejuni/isolamento & purificação , Genes Bacterianos , Aves Domésticas/microbiologia
6.
Transplant Proc ; 41(6): 2069-72, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19715834

RESUMO

Acute kidney injury (AKI) which is mainly produced by nephrotoxic or ischemic insults is correlated with a high mortality and morbidity. Proximal tubular epithelial cells (PTEC) play a major role. They are the main target of ischemia/reperfusion injury. PTECs have also been proposed as the effectors of AKI reversibility, but also as the creator of the inflammatory milieu: cytokine, chemokine, and complement expression. An important chemokine implicated in this process is monocyte chemotactic protein-1 (MCP-1) due to its ability to recruit and activate monocytes. Hepatocyte growth factor (HGF) is a pleiotropic factor with mitogenic, anti-apoptotic, and proliferative effects which has recently been studied for its anti-inflammatory and antifibrogenic effects. Our aim was to evaluate the potential inflammatory effect of hypoxia and reoxygenation on rat PTECs. We created a stable human HGF (hHGF) expressing PTEC line that emulated in vivo transfection and analyzed the role of this cell type in the induction and reversibility of AKI. Our results showed the efficiency of transfection with the hHGF gene to promote sustained expression of the protein in the medium (7627.13 +/- 1144.078 to 8211.3 +/- 795.37 pg/mL). When rat PTECs were under a hypoxia/reoxygenation insult, MCP-1 was highly overexpressed (4479.3 +/- 154.3 pg/mL of protein and 5.099 +/- 1.23 times control gene expression). Transfected cells abrogated this effect (288.7 +/- 13.5 pg/mL and 1.169 +/- 0.0759 times control). In conclusion, we observed that the hypoxia/reoxygenation insult stimulated MCP-1 protein secretion in PTECs and that PTECs which were stably transfected and overexpressing hHGF abrogated the inflammatory reaction mediated by hypoxia/reoxygenation, being a suitable model for later studies.


Assuntos
Quimiocina CCL2/genética , Células Epiteliais/fisiologia , Fator de Crescimento de Hepatócito/genética , Hipóxia/fisiopatologia , Túbulos Renais Proximais/fisiologia , Animais , Divisão Celular , Células Epiteliais/citologia , Citometria de Fluxo , Regulação da Expressão Gênica , Humanos , Inflamação/fisiopatologia , Túbulos Renais Proximais/citologia , Ratos , Transfecção , Regulação para Cima
7.
J Pathol ; 214(1): 104-13, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17973244

RESUMO

Macrophage infiltration is a common feature of the early phase of renal ischaemia/reperfusion injury. Indeed, it is generally regarded as the cause of tissue injury in this phase, although it is also clear that it can lead to tissue repair in other phases. In order to ascertain whether macrophages are directly involved in the repair/late phase, which follows the pro-inflammatory and injury process of renal ischaemia/reperfusion, we used two different approaches based on macrophage depletion. Firstly, we produced renal ischaemia in mice that were previously treated with clodronate liposome. Secondly, during reperfusion we re-injected RAW 264.7 to macrophage-depleted mice 24 h prior to sacrifice. The results showed that regeneration, as evaluated by stathmin and PCNA markers, was macrophage-dependent: it was blocked when macrophage depletion was provoked and recovered with macrophage re-injection. The cytokine profile revealed the influence of the inflammatory environment on kidney repair: pro-inflammatory cytokines (MCP-1, MIP-1alpha) increased during the early stages of reperfusion, coinciding with low regeneration, and the anti-inflammatory cytokine IL-10 increased during the longer periods of reperfusion when regeneration was more evident. We conclude that macrophages induce renal regeneration after ischaemia/reperfusion, depending on the inflammatory milieu.


Assuntos
Rim/irrigação sanguínea , Rim/fisiologia , Macrófagos/fisiologia , Regeneração/fisiologia , Traumatismo por Reperfusão/fisiopatologia , Transferência Adotiva , Animais , Ácido Clodrônico/administração & dosagem , Citocinas/biossíntese , Expressão Gênica/fisiologia , Mediadores da Inflamação/metabolismo , Rim/metabolismo , Rim/patologia , Lipossomos , Macrófagos/transplante , Masculino , Camundongos , Antígeno Nuclear de Célula em Proliferação/genética , Antígeno Nuclear de Célula em Proliferação/metabolismo , RNA Mensageiro/genética , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia
8.
Am J Transplant ; 7(9): 2180-9, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17697262

RESUMO

To assess the immediate and long-term effects of ischemic preconditioning (IPC) in deceased donor. liver transplantation (LT), we designed a prospective, randomized controlled trial involving 60 donors: control group (CTL, n = 30) or study group (IPC, n = 30). IPC was induced by 10-min hiliar clamping immediately before recovery of organs. Clinical data and blood and liver samples were obtained in the donor and in the recipient for measurements. IPC significantly improved biochemical markers of liver cell function such as uric acid, hyaluronic acid and Hypoxia-Induced Factor-1 alpha (HIF-1 alpha) levels. Moreover, the degree of apoptosis was significantly lower in the IPC group. On clinical basis, IPC significantly improved the serum aspartate aminotransferase (AST) levels and reduced the need for reoperation in the postoperative period. Moreover, the incidence of primary nonfunction (PNF) was lower in the IPC group, but did not achieve statistical significance. We conclude that 10-min IPC protects against I/R injury in deceased donor LT.


Assuntos
Precondicionamento Isquêmico/métodos , Transplante de Fígado/métodos , Doadores de Tecidos , Obtenção de Tecidos e Órgãos/métodos , Apoptose , Aspartato Aminotransferases/sangue , Biomarcadores/metabolismo , Western Blotting , Caspase 3/metabolismo , Feminino , Seguimentos , Humanos , Ácido Hialurônico/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Marcação In Situ das Extremidades Cortadas , Fígado/metabolismo , Fígado/patologia , Transplante de Fígado/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/prevenção & controle , Taxa de Sobrevida , Ácido Úrico/metabolismo
9.
Kidney Int ; 69(8): 1403-9, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16557219

RESUMO

In the last decade, various groups have found evidence of nitric oxide production by mitochondrial nitric oxide synthase (mNOS) in a range of experimental models. However, little is known about the role of mNOS in renal ischemia-reperfusion (I/R) injury and its possible involvement in the apoptotic pathway. We analyzed the role of mNOS in apoptosis promotion in rat kidney I/R and its direct implication through experiments in which isolated kidney mitochondria were subjected to hypoxia/reoxygenation. Results showed that neuronal NOS located in the inner mitochondrial membrane is upregulated during renal I/R and that this upregulation, together with the increase in nitric oxide production, is involved in the generation of intramitochondrial peroxynitrite, which in turn leads to cytochrome c release and apoptosis induction in renal I/R.


Assuntos
Apoptose , Isquemia/metabolismo , Mitocôndrias/enzimologia , Óxido Nítrico Sintase Tipo I/metabolismo , Ácido Peroxinitroso/metabolismo , Traumatismo por Reperfusão/metabolismo , Regulação para Cima , Animais , Biomarcadores , Western Blotting , Citocromos c/metabolismo , Densitometria , Inibidores Enzimáticos/farmacologia , Isquemia/etiologia , Rim/irrigação sanguínea , Masculino , Mitocôndrias/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Nitritos/metabolismo , Ratos , Ratos Wistar , Traumatismo por Reperfusão/etiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo
10.
Apoptosis ; 11(4): 563-71, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16528472

RESUMO

UNLABELLED: This study evaluated whether cytoskeletal alterations during the ischemic conditions associated with kidney preservation could determine apoptosis. Cytoskeletal alterations are among the main effects of ischemia and may induce apoptosis. Rat kidneys were preserved in University of Wisconsin (UW) solution for 24 h. Some groups of animals underwent 45 min of warm ischemia (WI) to evaluate its effect on both the actin cytoskeleton and apoptosis (assessed by caspase-3 activity and TUNEL staining). Swinholide A (SwinA) and Latrunculin B (LB), two actin cytoskeleton-targeted agents, were administered to assess the effect of direct actin disruption on apoptosis. Jasplakinolide (JP), a compound that stabilizes actin filaments, was administered to evaluate the effect of actin stabilization. Apoptosis was evaluated at 3 h of ex vivo reperfusion using the isolated perfused rat kidney (IPK) model. RESULTS: Apoptosis increased during reperfusion with WI or administration of actin disruptor agents. Administration of stabilizing agents reversed apoptosis in kidneys that had previously undergone WI or had received an actin disruptor agent. CONCLUSION: The disruption of the actin cytoskeleton during ischemic conditions associated with kidney preservation induces apoptosis upon reperfusion through caspase-3 activation.


Assuntos
Citoesqueleto de Actina/ultraestrutura , Apoptose , Rim/irrigação sanguínea , Traumatismo por Reperfusão/patologia , Citoesqueleto de Actina/efeitos dos fármacos , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Caspase 3 , Caspases/metabolismo , Rim/patologia , Rim/ultraestrutura , Masculino , Toxinas Marinhas/farmacologia , Técnicas de Cultura de Órgãos , Ratos , Ratos Wistar , Traumatismo por Reperfusão/enzimologia , Tiazóis/farmacologia , Tiazolidinas
11.
Apoptosis ; 9(3): 353-61, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15258467

RESUMO

Ischemic preconditioning has shown to reduce apoptosis in the intestinal mucosa during ischemia/reperfusion. This study evaluated if the decrease of apoptotic events found during preconditioning could be related with a reduction of the substrate (i.e., xanthine/hypoxanthine) available for xanthine oxidase (XO). Animals were randomly assigned to the following study groups: C, control; I/R, ischemia/reperfusion; P+I/R, ischemic preconditioning; P+I/R+H/X, ischemic preconditioning plus hypoxanthine/xanthine, and P+I/R+H/X+Allo, ischemic preconditioning plus hypoxanthine/xanthine plus allopurinol. Caspase-3 activity, DNA fragmentation and TUNEL staining increased in the I/R group compared to control. Ischemic preconditioning (P+I/R group) was able to reverse these apoptotic variables to a level similar to that of control rats. The addition of hypoxanthine/xanthine to rats subjected to ischemic preconditioning (P+I/R+H/X group) showed the highest apoptotic activity; however, further addition of allopurinol (P+I/R+H/X+Allo group) decreased significantly apoptotic activity and events. In conclusion, intestinal ischemic preconditioning is able to reduce apoptosis during the following sustained ischemia/reperfusion event because of a reduced accumulation of xanthine/hypoxanthine nucleotide.


Assuntos
Apoptose , Mucosa Intestinal/irrigação sanguínea , Intestino Delgado/fisiologia , Precondicionamento Isquêmico , Xantina Oxidase/metabolismo , Xantina/farmacologia , Alopurinol/farmacologia , Animais , Caspases/metabolismo , Inibidores Enzimáticos/farmacologia , Hipoxantinas/metabolismo , Mucosa Intestinal/citologia , Mucosa Intestinal/metabolismo , Masculino , Malondialdeído/análise , Malondialdeído/metabolismo , Ratos , Ratos Wistar , Traumatismo por Reperfusão/etiologia , Xantina/sangue , Xantina/metabolismo , Xantina Oxidase/antagonistas & inibidores , Xantina Oxidase/farmacologia
12.
Pflugers Arch ; 447(4): 387-91, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14605885

RESUMO

Renal injury due to ischaemia/reperfusion (I/R) leads to impaired renal function. One of the essential pathological changes thereby is cell death due to apoptosis. This study investigated the effect of adenosine administration on caspase-3 (C3) activity and expression during warm renal ischaemia in rat kidney and the role of nitric oxide (NO) as a mediator of the adenosine-induced effect. The following experimental groups were studied: control, ischaemia, ischaemia with adenosine administration, ischaemia with adenosine and N-nitro- l-arginine methyl ester (L-NAME) treatment and ischaemia with NO donor administration. C3 activity was measured and its protein expression determined by Western blot analysis. Supplementation of adenosine or NO during ischaemia increased C3 activity and protein expression but the effect of adenosine was reversed in rats treated with L-NAME. We conclude that adenosine increases C3 activity through an NO-dependent mechanism.


Assuntos
Adenosina/farmacologia , Caspases/metabolismo , Isquemia/metabolismo , Rim/irrigação sanguínea , Animais , Caspase 3 , Inibidores Enzimáticos/metabolismo , Marcação In Situ das Extremidades Cortadas , Isquemia/patologia , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Masculino , NG-Nitroarginina Metil Éster/metabolismo , Óxido Nítrico/metabolismo , Doadores de Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Traumatismo por Reperfusão
13.
Biosens Bioelectron ; 19(4): 391-9, 2003 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-14615098

RESUMO

It is commonly accepted that electrical impedance provides relevant information about the physiological condition of living tissues. Currently, impedance measurements are performed with relatively large electrodes not suitable for studies in small animals due to their poor spatial resolution and to the damage that they cause to the tissue. A minimally invasive needle shaped probe for electrical impedance measurements of living tissues is presented in this paper. This micro-probe consists of four square platinum electrodes (300 microm x 300 microm) on a silicon substrate (9 mm x 0.6 mm x 0.5 mm) and has been fabricated by using standard Si microelectronic techniques. The electrodes are not equally spaced in order to optimise the signal strength and the spatial resolution. Characterisation data obtained indicate that these probes provide high spatial resolution (measurement radius <4 mm) with a useful wide frequency band going from 100 Hz to 100 kHz. A series of in vivo experiments in rat kidneys subjected to ischemia was performed to demonstrate the feasibility of the probes and the measurement system. The impedance modulus and phase were measured at 1 kHz since this frequency is sufficiently low to permit the study of the extracellular medium. The extracellular pH and K+ were also simultaneously measured by using commercial miniaturised Ion Selective Electrodes. The induced ischemia period (45 min) resulted in significant changes of all measured parameters (Delta/Z/ approximately 65%; DeltapH approximately 0.8; DeltaK+ approximately 30 mM).


Assuntos
Técnicas Biossensoriais/instrumentação , Impedância Elétrica , Eletrodos , Nefropatias/diagnóstico , Nefropatias/fisiopatologia , Rim/fisiopatologia , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Agulhas , Animais , Técnicas Biossensoriais/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Isquemia/complicações , Isquemia/diagnóstico , Isquemia/fisiopatologia , Nefropatias/etiologia , Testes de Função Renal/instrumentação , Testes de Função Renal/métodos , Masculino , Ratos , Ratos Wistar , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
14.
Transplant Proc ; 35(5): 1931-2, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12962853

RESUMO

INTRODUCTION: Nitric oxide (NO) is an important mediator of both physiological and pathological responses. Its dual role in the ischemia-reperfusion syndrome is still a matter of controversy. The aim of this study was to analyze the effect of NO on apoptosis and cell necrosis associated with heterotopic small bowel transplant. METHODS: Sprague-Dawley rats underwent heterotopic small bowel transplants with 3 hours of cold ischemia and 5 hours of reperfusion. Animals were assigned to the following study groups: Sham; bowel transplant (Trp); bowel transplant + NO donor (Trp + NONOS); bowel transplant + NO synthesis inhibitor (Trp + L-NAME). We studied histological changes and bacterial translocation in mesenteric nodes, liver and spleen as parameters of cell necrosis and caspase-3 activity as a parameter of apoptosis. RESULTS: Histological changes and bacterial translocation showed that exogenous administration of NO protected the transplant. Simple bowel transplant, with or without inhibition of NO synthesis, did not display this protective effect. Significantly greater levels of apoptosis were observe in grafts among the group administered NO at pharmacological doses. CONCLUSIONS: In experimental bowel transplantation rats administered exogenous NO show less necrosis but at the same time stimulation of apoptosis.


Assuntos
Apoptose/fisiologia , Translocação Bacteriana , Sobrevivência de Enxerto/efeitos dos fármacos , Intestinos/patologia , Intestinos/transplante , NG-Nitroarginina Metil Éster/uso terapêutico , Doadores de Óxido Nítrico/uso terapêutico , Óxido Nítrico/uso terapêutico , Espermina/análogos & derivados , Espermina/uso terapêutico , Transplante Homólogo/patologia , Animais , Apoptose/efeitos dos fármacos , Masculino , Necrose , Óxidos de Nitrogênio , Ratos , Ratos Sprague-Dawley , Transplante Heterólogo , Transplante Homólogo/métodos
15.
Clin Exp Pharmacol Physiol ; 30(4): 242-8, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12680841

RESUMO

1. The present study investigated the effects of kidney ischaemia duration on nitric oxide (NO) and superoxide (O2-) generation at reperfusion and the role of xanthine and adenosine as mediators of NO/O2- generation. 2. The effect of the duration of ischaemia on renal nucleotide levels was studied in two ischaemic groups (10 and 30 min). The role of adenosine and xanthine was studied in ischaemic-reperfused groups (subjected to 10 and 30 min ischaemia and 60 min reperfusion). 3. Tissue levels of adenosine decreased significantly after 30 min ischaemia, whereas xanthine/hypoxanthine levels increased concomitantly with renal dysfunction and histological damage. 4. Nitric oxide production increased significantly after 10 min ischaemia and 60 min reperfusion, whereas lipoperoxidation increased significantly after 30 min ischaemia and 60 min reperfusion. The administration of theophylline (40 mg/kg, i.p.) reversed the early increase in NO production. 5. Xanthine supplementation decreased renal function and increased lipoperoxidation. 6. In conclusion, NO/O2- production and the subsequent renal injury/dysfunction may be modified by changes in the adenosine and xanthine levels of the injured kidney, although the present data show a significant in vivo role only for xanthine.


Assuntos
Adenosina/metabolismo , Nefropatias/metabolismo , Óxido Nítrico/biossíntese , Traumatismo por Reperfusão/metabolismo , Superóxidos/metabolismo , Xantina/metabolismo , Animais , Nitrogênio da Ureia Sanguínea , Creatinina/sangue , Rim/irrigação sanguínea , Rim/metabolismo , Rim/patologia , Nefropatias/patologia , Peroxidação de Lipídeos , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
16.
Transplantation ; 75(6): 744-9, 2003 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-12660495

RESUMO

BACKGROUND: Microelectrode technology is a promising tool for monitoring kidney ischemia and the changes induced by its therapeutic management. Ischemic preconditioning, that is, brief ischemic periods before sustained ischemia, has been shown to protect several organs, including the kidney, from ischemia-reperfusion injury. We tested whether the effect of preconditioning could be appraised by real-time measurement of parameters representative of tissue hypoxia. METHODS: In a sample of pentobarbital-anesthetized and mechanically ventilated rats, we studied the effect of renal ischemic preconditioning (10-min ischemia and 10-min reflow interval) on subsequent ischemia-reperfusion (45 min and 60 min). Renal tissue electrical impedance, extracellular pH, and potassium concentration [K+] were measured continuously by implanted microelectrodes. RESULTS: Ischemia induced an early, rapid rise in extracellular potassium and impedance module, followed by a phase of slower increase, whereas pH decreased rapidly, reaching a plateau. Preconditioning treatment did not cause significant changes in interstitial pH and [K+] but increased ischemic tissue impedance. During reperfusion, the three variables recovered progressively; however, after a decline, electrical impedance showed a clear postischemic increase. This rise was suppressed by preconditioning. CONCLUSIONS: Real-time measurement of any of the three parameters showed capability for early detection of ischemia. In contrast with findings in myocardial tissue, preconditioning in the kidney did not increase potassium cell loss during ischemia or improve ischemic acidosis or tissue impedance. Electrical impedance increased for a second time during reperfusion, indicating the presence of a postischemic cellular edema; concealing this episode was the most noticeable effect of the preconditioning treatment.


Assuntos
Precondicionamento Isquêmico , Transplante de Rim , Rim/irrigação sanguínea , Monitorização Fisiológica/métodos , Traumatismo por Reperfusão/diagnóstico , Acidose/diagnóstico , Animais , Modelos Animais de Doenças , Impedância Elétrica , Rim/fisiologia , Masculino , Microeletrodos , Potássio/metabolismo , Ratos , Ratos Wistar , Artéria Renal/fisiologia , Instrumentos Cirúrgicos
17.
Microbiology (Reading) ; 148(Pt 10): 3019-3027, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12368435

RESUMO

A better tuberculosis vaccine is urgently required to control the continuing epidemic. Molecular techniques are now available to produce a better live vaccine than BCG by producing avirulent strains of the Mycobacterium tuberculosis complex with known gene deletions. In this study, 1000 illegitimate recombinants of Mycobacterium bovis were produced by illegitimate recombination with fragments of mycobacterial DNA containing a kanamycin resistance gene. Eight recombinant strains were selected on the basis of their inability to grow when stationary-phase cultures were inoculated into minimal medium. Five of these recombinants were found to be avirulent when inoculated into guinea pigs. Two of the avirulent recombinants produced vaccine efficacy comparable to BCG against an aerosol challenge in guinea pigs with M. bovis. One of these recombinants had an inactivated glnA2 gene encoding a putative glutamine synthetase. Transcriptional analysis showed that inactivation of glnA2 did not affect expression of the downstream glnE gene. The other recombinant had a block of 12 genes deleted, including the sigma factor gene sigG. Two avirulent recombinants with an inactivated pckA gene, encoding phosphoenolpyruvate carboxykinase which catalyses the first step of gluconeogenesis, induced poor protection against tuberculosis. It is clear that live avirulent strains of the M. tuberculosis complex vary widely in their ability as vaccines to protect against tuberculosis. Improved models may be required to more clearly determine the difference in protective effect between BCG and potential new tuberculosis vaccines.


Assuntos
Mutação , Mycobacterium bovis/crescimento & desenvolvimento , Mycobacterium bovis/patogenicidade , Recombinação Genética , Vacinas contra a Tuberculose , Tuberculose/prevenção & controle , Animais , Vacina BCG/administração & dosagem , Vacina BCG/imunologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Deleção de Genes , Glutamato-Amônia Ligase/genética , Glutamato-Amônia Ligase/metabolismo , Cobaias , Mycobacterium bovis/genética , Mycobacterium bovis/imunologia , Tuberculose/microbiologia , Tuberculose/fisiopatologia , Vacinas contra a Tuberculose/administração & dosagem , Vacinas contra a Tuberculose/imunologia , Vacinação , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , Virulência
18.
Shock ; 16(5): 403-8, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11699082

RESUMO

During intestinal ischemia, CO2 accumulates in tissue as a result of bicarbonate buffering of anaerobic acid generation. Previous studies have shown that nitric oxide (NO) generated during ischemic preconditioning acts as a glycolytic modulator, thus decreasing tissue lactate production. We studied if ischemic preconditioning induces NO-dependent changes in static mesenteric venous blood Pco2 values and CO2 accumulation during intestinal ischemia. Superior mesenteric venous (smv) acid base variables were studied in 4 groups of rats: a control group (C), an ischemic (90-min period of flow arrest) group (I), an ischemic group subjected to previous ischemic preconditioning (P), and an ischemic group subjected to previous ischemic preconditioning in which nitric oxide synthase (NOS) was inhibited by N-nitro-L-arginine methyl ester (L-NAME) administration (P+N). Preconditioning induced acidosis in smv blood during reperfusion before ischemia, but this effect was counteracted by L-NAME. Group P showed the lowest values of end-ischemic tissue lactate, smv blood CO2 accumulation, and LDH in perfusate, whereas group P+N showed the highest level of LDH in perfusate but the lowest end-ischemic smv blood Pco2 and acidity. We conclude that lower ischemic CO2 accumulation in static smv blood, but not lower end-ischemic Pco2, was related with the protective effect of ischemic preconditioning in our rat model. Thus, the use of stagnant smv blood Pco2 as an indicative of intestinal dysoxia can lead to misinterpretations if a broader acid-base picture is not considered.


Assuntos
Dióxido de Carbono/sangue , Intestinos/irrigação sanguínea , Isquemia/sangue , Precondicionamento Isquêmico , NG-Nitroarginina Metil Éster/farmacologia , Anaerobiose , Animais , Biomarcadores/sangue , Concentração de Íons de Hidrogênio , Isquemia/fisiopatologia , L-Lactato Desidrogenase/análise , Lactatos/sangue , Masculino , Óxido Nítrico/sangue , Ratos , Ratos Wistar , Fatores de Tempo
19.
Br J Surg ; 88(10): 1366-75, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11578294

RESUMO

BACKGROUND: During cold preservation, cellular consumption of adenosine triphosphate leads to the accumulation of nucleotides and nucleosides. The precise role of adenosine in modulating the inflammatory response of cold-preserved pancreas after reperfusion remains to be elucidated. The aim of this study was to assess the influence of adenosine on the inflammatory response associated with the process of ischaemia-reperfusion in rat pancreas transplantation. METHODS: The effect of adenosine from preservation solution on the levels of high-energy nucleotides and their breakdown products after cold ischaemic preservation was determined. In addition, the inflammatory response associated with the process of ischaemia-reperfusion in pancreas transplantation was quantified with and without pretreatment with the adenosine antagonist theophylline, and during preservation of the organ in University of Wisconsin solution with and without adenosine. RESULTS: Adenosine from preservation solution is able to modify the nucleotide and nucleoside content of preserved pancreas, indicating that adenosine is incorporated and metabolized in tissue. Administration of the adenosine antagonist to transplanted rats moderated the increases in nitrite and nitrate, myeloperoxidase activity and lipoperoxidation levels in the pancreas. CONCLUSION: Adenosine in the preservation solution may enhance the inflammatory response in rat pancreas transplantation.


Assuntos
Adenosina/farmacologia , Transplante de Pâncreas/efeitos adversos , Traumatismo por Reperfusão/etiologia , Adenosina/fisiologia , Animais , Sobrevivência de Enxerto , Inflamação , Lipase/sangue , Masculino , Neutrófilos/patologia , Óxido Nítrico/análise , Nucleotídeos/metabolismo , Ratos , Ratos Sprague-Dawley
20.
FEMS Microbiol Lett ; 200(2): 151-5, 2001 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-11425467

RESUMO

A 17-kDa protein (CadI) was induced by cadmium in Mycobacterium bovis and Mycobacterium tuberculosis. Comparison of the N-terminal sequence from M. bovis CadI with the annotated M. tuberculosis genome database identified Rv2641 as the encoding gene. Long and short promoter fragments from M. bovis cadI were fused to the lacZ reporter gene in pYUB76. Only the long fragment directed cadmium-inducible activity when electroporated into M. bovis. The cadI promoter has potential for both constitutive and inducible expression studies in M. bovis and M. tuberculosis.


Assuntos
Cádmio/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Mycobacterium bovis/efeitos dos fármacos , Mycobacterium tuberculosis/efeitos dos fármacos , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Dados de Sequência Molecular , Peso Molecular , Mycobacterium bovis/genética , Mycobacterium tuberculosis/genética , Regiões Promotoras Genéticas/efeitos dos fármacos , Homologia de Sequência de Aminoácidos
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