RESUMO
We report the use of resazurin (AlamarBlue) dye in a robust assay for cell viability of primary cells. Human mononuclear cells were used here for immunological studies, but the method can be applied to monitor reduction potential of any living cell. Reduction of AlamarBlue dye is widely used in several commercial assays of cell viability. Although it is fast and easy with immortal cell lines, the method is impractical for the primary cells due to their slower metabolic activity. We propose that the viability of human primary cells can be determined with AlamarBlue by monitoring the increase in fluorescence intensity in a matter of a few hours. In the presence of AlamarBlue, the dynamic increase in cellular reduction capacity is linear for several hours or, alternatively, the assay can be repeated to monitor the viability at any time point of cell culture. In addition to testing cellular growth rates and cytotoxicity, the application can be used to compare sample quality of cells that have been frozen or represent a pool of multiple donors. This application of the AlamarBlue cell viability assay is simple, rapid, and cost-effective, and therefore it is also well suited for high-throughput studies.
Assuntos
Leucócitos Mononucleares/citologia , Espectrometria de Fluorescência/métodos , Sobrevivência Celular , Células Cultivadas , Corantes/metabolismo , Humanos , Oxazinas/metabolismo , Fatores de Tempo , Xantenos/metabolismoRESUMO
The growing disparity between organ supply and demand has become the greatest hurdle facing transplant professionals and life-saving transplants. Because the organ shortage has become the rate-limiting step to effective transplants, it is critical for the transplant community to identify viable mechanisms to expand the donor pool and use every available allograft. Although using kidneys from deceased donors whose demise was secondary to ethylene glycol (EG) toxicity requires great deliberation and precise timing as described by Barbas et al [5], using hepatic allografts in this setting involves far less risk. The following is a discussion of a 61-year-old male who was diagnosed with end-stage liver disease secondary to non-alcoholic steatohepatitis and ultimately underwent a life-saving transplant with a liver recovered from a donor with EG-induced brain death and allocated nationally due to trepidation by local and regional centers to use the liver from a donor after EG toxicity.
Assuntos
Morte Encefálica , Doença Hepática Terminal/cirurgia , Transplante de Fígado/métodos , Doadores de Tecidos/provisão & distribuição , Obtenção de Tecidos e Órgãos/métodos , Adulto , Etilenoglicol/intoxicação , Humanos , Masculino , Pessoa de Meia-Idade , Suicídio , Transplante Homólogo/métodos , Transplantes/fisiologiaRESUMO
BACKGROUND: These experiments investigated the ability of the donor-specific unresponsiveness created by the intrathymic inoculation of donor alloantigen to effectively prevent chronic rejection in an established rat model of chronic renal allograft rejection. METHODS: Three study groups were examined: (1) Allograft controls--F-344 rats received a Lewis renal allograft plus 10 days of low-dose cyclosporine (CsA); (2) isograft controls--F-344 rats received an F-344 renal isograft and low-dose CsA; (3) experimental group--F-344 rats received a T-cell depleted syngeneic bone marrow transplant and intrathymic injection of Lewis bone marrow. Twenty-one days after bone marrow transplant, these animals received a Lewis renal allograft. RESULTS: Allograft controls demonstrated severe parenchymal fibrosis; isograft controls and intrathymic (IT) animals failed to develop this lesion. Immunohistochemical analysis revealed increased CD4+ T cells infiltrating the cortex of the allograft controls. Cytokine interferon-gamma and interleukin-2 transcripts were strongly positive in allograft controls and were absent from isograft controls and IT allografts as determined by reverse transcriptase-polymerase chain reaction. Analysis of tolerant grafts by flow microfluorimetry and genomic DNA amplification could not detect chimerism to a level of < 0.1%. CONCLUSION: IT inoculation of donor alloantigen can confer long-term unresponsiveness and prevent the development of the characteristic lesions of chronic rejection.
Assuntos
Transplante de Medula Óssea/imunologia , Rejeição de Enxerto/prevenção & controle , Tolerância Imunológica , Isoantígenos/farmacologia , Transplante de Rim/imunologia , Quimeras de Transplante , Animais , Injeções , Isoantígenos/administração & dosagem , Isoantígenos/uso terapêutico , Transplante de Rim/patologia , Depleção Linfocítica , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Timo , Transplante HomólogoRESUMO
BACKGROUND: The major impediment to success in solid organ transplantation is chronic rejection (CR). The characteristic lesion of CR is transplant vascular sclerosis (TVS). Although the mechanism of TVS is thought to have an immunologic basis, in humans immunosuppression does not prevent or reverse it. One possible therapy to prevent TVS is induction of donor-specific tolerance. Bone marrow chimerism has been successful in inducing tolerance in acute and chronic rejection heart and kidney transplant models. The highly immunogenic small bowel (SB) allograft provides a rigorous test of the efficacy of this tolerance regimen. We examined whether induction of tolerance by bone marrow chimerism could prevent TVS in a model of Fisher 344 (F344) to Lewis (LEW) rat SB transplantation. METHODS: Bone marrow chimeras (BMC) were created by transplantation of T-cell-depleted F344 bone marrow into irradiated LEW rats. Chimerism was assessed by flow cytometric method. F344 SB, heterotopically transplanted into the chimeras, was clinically and histologically assessed for CR. F344 SB grafts, transplanted into cyclosporine-A-treated LEW recipients, served as control grafts for CR. RESULTS: Cyclosporine-A-treated LEW rats chronically rejected F344 SB grafts. By contrast, the BMC group demonstrated tolerance and had long-term SB graft survival (>120 days) without TVS. The BMC demonstrated immunocompetence by prompt rejection of third party ACI (RT1av1) SB allografts. CONCLUSIONS: Bone marrow chimerism prevents chronic graft failure secondary to TVS in a model of chronic SB rejection. TVS fails to develop when tolerance is established, suggesting that the mechanisms involved in TVS are, in part, immunologically mediated.
Assuntos
Medula Óssea/fisiologia , Quimera/imunologia , Rejeição de Enxerto/complicações , Tolerância Imunológica/fisiologia , Intestino Delgado/irrigação sanguínea , Intestino Delgado/transplante , Doenças Vasculares/prevenção & controle , Animais , Doença Crônica , Rejeição de Enxerto/patologia , Intestino Delgado/patologia , Masculino , Ratos , Ratos Endogâmicos ACI , Ratos Sprague-Dawley , Esclerose/prevenção & controle , Doenças Vasculares/etiologia , Doenças Vasculares/patologiaRESUMO
Chronic rejection is a major cause of graft failure in solid organ transplants after the first year. A characteristic lesion in a variety of chronically rejecting organs is a fibrointimal proliferative arteriosclerosis. It has been speculated that approaches to tolerance induction may be effective in obviating not only acute, but also chronic, rejection. A picture of chronic rejection develops naturally in heart grafts transplanted from the Lewis-to-F-344 strain of rat. We examined whether tolerance induction by bone marrow transplantation and development of hematopoietic chimerism or tolerance induction by intrathymic inoculation of alloantigen could effectively prevent chronic rejection in an established model of chronic rejection. Bone marrow chimeras were developed in F-344 hosts by transplantation of T cell-depleted allogeneic marrow (TCD A BMT). Another set of F-344 hosts was inoculated with intrathymic allogeneic bone marrow cells. Heart grafts in these animals demonstrated tolerance for 120 days after transplantation. Control F-344 animals treated with a short course of cyclosporine consistently developed chronic rejection by 120 days following heart transplantation. Strikingly absent from the tolerant animals was any sign of graft arteriosclerosis, which was demonstrated in the vast majority of control animals. Analysis of cytokine mRNA profiles at 30 days following heart transplantation demonstrated differences between control and tolerant animals. These results suggest that tolerance induction can effectively prevent chronic rejection.
Assuntos
Arteriosclerose/prevenção & controle , Rejeição de Enxerto/prevenção & controle , Quimeras de Transplante/imunologia , Animais , Arteriosclerose/etiologia , Transplante de Medula Óssea/imunologia , Doença Crônica , Vasos Coronários/fisiologia , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Rejeição de Enxerto/complicações , Rejeição de Enxerto/imunologia , Transplante de Coração/efeitos adversos , Transplante de Coração/imunologia , Tolerância Imunológica , Isoantígenos/imunologia , Masculino , Miocárdio/patologia , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Linfócitos T/imunologiaRESUMO
This is the first report of the use of a free jejunal autograft vascularized by the internal thoracic (internal mammary) artery and vein to restore continuity of the digestive tract after total gastrectomy and distal 65% esophagectomy for recurrent bleeding esophagogastric varices caused by unshuntable extrahepatic portal hypertension. The procedure was used in two young adults who, because of numerous previous abdominal operations, had a severely scarred and contracted intestinal mesentery that precluded conventional use of the small or large intestine with an intact blood supply to bridge the gap between the upper thoracic esophagus and the abdominal jejunum. Before referral, the two patients had 21 and eight bouts of variceal hemorrhage, respectively, that necessitated a cumulative total of 108 and 74 units of blood transfusion, necessitated 17 and 12 admissions to the hospital, and failed to respond to four and five operations and 14 and 18 sessions of endoscopic sclerotherapy. After extensive esophagogastrectomy combined with a free jejunal autograft, both patients have done well during follow-up of 9 and 3 years, respectively. Both have been in good to excellent health with stable weight, freedom from digestive tract bleeding, normal liver function, and no encephalopathy. These results confirm our recently reported conclusions regarding the uniform long-term effectiveness of extensive esophagogastrectomy in the treatment of unshuntable extrahepatic portal hypertension and suggest that thoracic and general surgeons familiar with microvascular techniques may find the free jejunal autograft to be useful in various circumstances in which it is necessary to replace all or a substantial part of the thoracic esophagus.
Assuntos
Esofagectomia , Gastrectomia , Hipertensão Portal/cirurgia , Jejuno/transplante , Adulto , Anastomose em-Y de Roux , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/cirurgia , Esôfago/cirurgia , Feminino , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/cirurgia , Humanos , Hipertensão Portal/complicações , Masculino , Transplante AutólogoRESUMO
BACKGROUND: The induction of specific tolerance would greatly improve survival and functional state of organ transplant recipients. One approach that has recently received attention is the creation of mixed hematopoietic chimerism through the transplantation of allogeneic and syngeneic T-cell-depleted (TCD) bone marrows. In these studies we examined whether tolerance to highly immunogenic small-bowel transplants could be induced by mixed allogeneic chimerism. Tolerance induction depends on the sharing of antigens between bone marrow cells and small-bowel tissue. METHODS: Adult Lewis rats were lethally irradiated and reconstituted with a mixture of 50 x 10(6) TCD bone marrow cells. Thirty days after reconstitution, animals were tested for chimerism by fluorescence-activated cell sorter analysis. Chimeric animals then received ACI heterotopic small-bowel allografts and were assessed daily for rejection. Small-bowel allograft survival was compared to three control groups: (1) untreated Lewis recipients, (2) irradiated TCD syngeneically reconstituted Lewis recipients, and (3) Lewis bone marrow recipients that did not develop chimerism. RESULTS: Median graft survival in control groups was 8 days. Graft survival in eight mixed chimeras ranged from more than 135 to more than 304 days (p < 0.0001), and no episode of rejection or graft-versus-host disease was observed. Mixed lymphocyte reactivity of chimeric lymphocytes confirmed in vivo observation of tolerance. CONCLUSIONS: Bone marrow cells share tissue-specific antigens with small-bowel cells to permit induction of tolerance.
Assuntos
Tolerância Imunológica , Intestino Delgado/transplante , Animais , Quimera , Doença Enxerto-Hospedeiro/etiologia , Intestino Delgado/patologia , Depleção Linfocítica , Masculino , Ratos , Ratos Endogâmicos ACI , Ratos Endogâmicos BN , Ratos Sprague-Dawley , Transplante HomólogoRESUMO
The induction of tolerance to organ allografts would eliminate acute and chronic rejection as well as the need for nonspecific immunosuppression. We have shown that tolerance induced through the creation of mixed allogeneic bone marrow chimeras allows for the long-term engraftment of cardiac and small bowel allografts across strong multiple major histocompatibility barriers. The possibility that tolerance might render the host susceptible to graft-versus-host disease (GVHD) has not been investigated in this or other models of tolerance. To test this possibility chimeras were created by transplantation of T-cell depleted ACI and Lewis bone marrow into lethally irradiated Lewis rats. Chimerism was determined post bone marrow transplant (BMTx) by flow cytometry of lymphocytes from reconstituted animals. ACI/Lew chimeras (ALC), Lewis/ACI F1 (LACF1), and Lewis (LEW) rats all received heterotopic ACI vascularized small bowel grafts. A second group of chimeras received small bowel grafts from ACI rats pretreated with low dose irradiation to eliminate T-cells from the graft. LEW-->LEW small bowel isografts were also performed. Animals were examined for evidence of GVHD by clinical signs and histologic examination of biopsied tissues. GVHD was quantified using the popliteal lymph node enlargement assay. All LACF1 rats developed severe lethal GVHD following ACI small bowel transplant. Bone marrow chimeras, ALC (n = 6), developed fatal GVHD in a similar fashion after receiving a small bowel transplant. LEW-->LEW isografts and chimeras receiving bowel from irradiated ACI rats survived long term without GVHD while ACI-->LEW allogeneic transplants all underwent acute rejection. GVHD or its absence was confirmed histologically. Popliteal lymph node enlargement indices reflected the presence of GVHD in the chimeras (1.87) and LACF1 (5.4) receiving allografts, but not in isografts or chimeras receiving irradiated allogeneic transplants. Analysis of cytokines in the tongues of rats undergoing GVHD showed elaboration of Th1 type proinflammatory cytokines which was not seen in isografted rats or rats receiving preirradiated small bowel. These results demonstrate that tolerance induction through mixed chimerism results in susceptibility to small bowel induced GVHD. Preirradiating the donor bowel prior to SBTx can prevent GVHD.
Assuntos
Doença Enxerto-Hospedeiro/imunologia , Tolerância Imunológica/imunologia , Intestino Delgado/imunologia , Intestino Delgado/transplante , Quimeras de Transplante/imunologia , Animais , Medula Óssea/imunologia , Transplante de Medula Óssea/imunologia , Citocinas/análise , Doença Enxerto-Hospedeiro/patologia , Masculino , Ratos , Ratos Endogâmicos Lew , Doadores de Tecidos , Transplante Homólogo/imunologiaRESUMO
BACKGROUND: Chronic rejection is the leading cause of late graft loss in kidney transplantation. We tested the ability of mixed hematopoietic chimerism to prevent chronic renal allograft rejection in an established rat model and described possible mechanisms responsible for this tolerance. METHODS: Mixed hematopoietic chimerism was established in lethally irradiated F-344 rats by reconstitution with Lewis bone marrow. Four groups (n = 5 each) received orthotopic kidney transplants: (1) allograft controls, (2) isograft controls, (3) experimental chimeras, and (4) specificity control. After 120 days kidney grafts were examined histologically, immunohistochemically, and for cytokine interferon-gamma, interleukin-2 (IL-2), IL-4, and IL-10 gene transcripts by means of reverse transcriptase polymerase chain reaction techniques. RESULTS: Allograft control group exhibited severe parenchymal fibrosis; isograft control and chimera groups failed to develop this lesion. Immunohistochemical analysis revealed increased CD8+ lymphocytes and ED-1+ monocyte-macrophages infiltrating the tubulointerstitium of control allografts. Interferon-gamma and IL-2 were absent in isografts. IL-4 was absent and IL-10 was positive in all grafts. Chimeras promptly rejected third-party allografts. CONCLUSIONS: Induction of specific tolerance through mixed hematopoietic chimerism prevents chronic renal allograft rejection. These results support the hypothesis of an immunologic basis of chronic rejection and advance previous observations that the induction of specific tolerance enables long-term solid organ transplantation without the use of immunosuppression.
Assuntos
Rejeição de Enxerto/prevenção & controle , Tolerância Imunológica/imunologia , Transplante de Rim/imunologia , Animais , Transplante de Medula Óssea/imunologia , Quimera , Doença Crônica , Citocinas/genética , Hematopoese/imunologia , Imuno-Histoquímica , Leucócitos Mononucleares/citologia , Contagem de Linfócitos , RNA Mensageiro/análise , Ratos , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Transcrição Gênica/imunologia , Transplante Homólogo/imunologiaRESUMO
BACKGROUND: The induction of specific tolerance could prevent acute and chronic rejection, as well as immunosuppressive complications, in recipients of vascularized organ allografts. Mixed hematopoietic chimerism is one approach to allogeneic tolerance. In these studies we examined whether mixed chimerism can confer tolerance to heart allografts across major and minor histocompatiblity barriers. We also examined the transcription of cytokine genes within the allografts of tolerance animals and in cell culture. METHODS: Adult Lewis rats were lethally irradiated and reconstituted with a mixture of 50 x 10(6) T-cell depleted bone marrow cells. Chimeric animals received heterotopic donor strain and third-party heart allografts and were assessed daily for rejection. Another set of chimeras received heart allografts that were examined at varying time points for transcription of cytokine genes by reverse-transcriptase polymerase chain reaction. RESULTS: Median graft survival in control animals was 6 days. Graft survival in 11 mixed chimeras ranged from more than 165 to more than 274 days (p < 0.001), and no episode of rejection or graft-versus-host disease was observed. Examination of cytokine transcriptions revealed dramatic alterations in interleukin-4 transcription in vivo and in vitro. CONCLUSIONS: Alterations in cytokine gene transcription are descriptive of tolerance in this model. Mixed chimerism confers long-term unresponsiveness to heart allografts across major and minor histocompatibility barriers with desirable features for clinical application.
Assuntos
Quimera , Hematopoese , Tolerância Imunológica , Interleucina-4/metabolismo , Animais , Transplante de Medula Óssea , Citocinas/genética , Sobrevivência de Enxerto , Interleucina-4/genética , Masculino , Ratos , Ratos Endogâmicos BN , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Transcrição GênicaRESUMO
Thirty-three patients with Budd-Chiari syndrome were studied for 1 to 19 years following portal decompression. All had ascites, hepatomegaly, abnormal liver function, angiographic demonstration of inferior vena cava and/or hepatic vein occlusion, and biopsy specimens showing intense hepatic congestion and necrosis. When thrombosis was confined to hepatic veins (20 patients), side-to-side portacaval shunt resulted in 95% operative survival, 90% prolonged survival, permanent shunt patency, relief of ascites, reversal of liver dysfunction, and reversal or improvement of hepatic lesions. When thrombosis involved the inferior vena cava, mesoatrial shunt (eight patients) was unsatisfactory because of a 63% mortality rate from liver failure due to shunt thrombosis. In contrast, a new procedure consisting of combined portacaval and caval-atrial shunts (five patients) has been highly successful, with 100% survival, shunt patency, relief of ascites, and reversal of pathologic abnormalities.
Assuntos
Síndrome de Budd-Chiari/cirurgia , Derivação Portocava Cirúrgica/métodos , Adulto , Síndrome de Budd-Chiari/patologia , Feminino , Seguimentos , Átrios do Coração/cirurgia , Veias Hepáticas/patologia , Humanos , Fígado/patologia , Fígado/fisiopatologia , Cirrose Hepática/prevenção & controle , Masculino , Veias Mesentéricas/transplante , Pessoa de Meia-Idade , Sistema Porta/fisiologia , Qualidade de Vida , Taxa de Sobrevida , Trombose/patologia , Grau de Desobstrução Vascular , Veia Cava Inferior/patologiaRESUMO
BACKGROUND: Mesangial enlargement (ME) is one of the hallmark lesions of diabetic nephropathy and plays a major role in diabetic renal failure. Conventional treatment of type 1 diabetes mellitus with insulin injections, diet, and medications has often failed to prevent development and progression of ME, presumably because of difficulty in achieving tight metabolic control. Although many pancreas transplantations have been done in patients with type 1 diabetes mellitus, there is insufficient information about their influence on ME or other diabetic lesions that are responsible for its morbidity and mortality. HYPOTHESIS: Whole pancreas transplantation will prevent diabetic ME throughout the life of the rat with alloxan-induced diabetes mellitus. DESIGN: Mesangial enlargement was studied for 28 months by a highly reproducible quantitative morphologic method in 55 nondiabetic control rats, 57 control rats with alloxan-induced diabetes mellitus, 97 diabetic rats that received a pancreaticoduodenal isograft shortly after the induction of diabetes mellitus, and 126 diabetic rats that received a duct-ligated pancreas isograft shortly after the induction of diabetes mellitus. Mesangial enlargement was determined by measuring the area occupied by camera lucida tracings of the mesangium using an electronic planimeter connected to a computer. RESULTS: Monthly metabolic studies showed that whole pancreas transplantation maintained very tight metabolic control of diabetes mellitus. Alloxan-induced diabetes mellitus produced progressive accumulation of mesangial matrix and progressive enlargement of all elements of the mesangium during the study. The 2 types of whole pancreas transplants provided lifelong protection against abnormal ME (P = .006). CONCLUSIONS: These results, combined with our previous finding of lifelong prevention of abnormal glomerular capillary basement membrane thickening, demonstrate that whole pancreas transplantation performed early in the course of alloxan-induced diabetes mellitus is capable of preventing diabetic kidney lesions. Moreover, these results suggest that whole pancreas transplants might be useful preventive therapy in patients with diabetes mellitus who undergo kidney transplantation for renal failure, in whom recurrence of nephropathy often develops in the transplanted kidney.
Assuntos
Diabetes Mellitus Experimental/cirurgia , Nefropatias Diabéticas/prevenção & controle , Mesângio Glomerular/patologia , Transplante de Pâncreas , Animais , Duodeno/transplante , Ratos , Ratos Endogâmicos LewRESUMO
The decapeptide form of human gastrin releasing peptide was isolated from acid extracts of liver tissue containing a metastatic human bronchial carcinoid tumor. A larger form also was isolated and partially characterized. During gel permeation chromatography the major immunoreactive peak eluted in the same region as synthetic gastrin releasing decapeptide while a second minor immunoreactive peak eluted near gastrin releasing peptide. Bombesin-like immunoreactivity (BLI) was purified by successive applications to reverse phase high pressure liquid chromatography (HPLC) columns. After four successive HPLC purifications a single peak of bombesin-like immunoreactivity was detected. Amino acid analysis, microsequence analysis and coelution with synthetic peptide indicated that the predominant form present in metastatic tumor tissue was identical to the decapeptide form of canine gastrin-releasing peptide. The less abundant form was purified by cation exchange chromatography followed by reverse phase high pressure liquid chromatography. Partial microsequence analysis of this peptide, through the first 11 residues, was Val-Pro-Leu-Pro-Ala-Gly-Gly-Gly-Thr-Val-Leu. This sequence differed from that of hog heptacosapeptide gastrin releasing peptide at positions 1,3,4 and 5 and from the canine peptide as positions 1,3,5, and 7.
Assuntos
Bombesina/isolamento & purificação , Peptídeos/isolamento & purificação , Sequência de Aminoácidos , Aminoácidos/análise , Neoplasias Brônquicas/análise , Neoplasias Brônquicas/patologia , Carcinoma Adenoide Cístico/análise , Carcinoma Adenoide Cístico/patologia , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Humanos , Fígado/análise , Neoplasias Hepáticas/análise , Neoplasias Hepáticas/secundárioRESUMO
The catabolism of two gastric neuropeptides, the C-terminal decapeptide of gastrin releasing peptide-27 (GRP10) and substance P (SP), by membrane-bound peptidases of the porcine gastric corpus and by porcine endopeptidase-24.11 ("enkephalinase") has been investigated. GRP10 was catabolized by gastric muscle peptidases (specific activity 1.8 nmol min-1 mg-1 protein) by hydrolysis of the His8-Leu9 bond and catabolism was inhibited by phosphoramidon (I50 approx. 10(-8) M), a specific inhibitor of endopeptidase-24.11. The same bond in GRP10 was cleaved by purified endopeptidase-24.11, and hydrolysis was equally sensitive to inhibition by phosphoramidon. SP was catabolized by gastric muscle peptidases (specific activity 1.7 nmol min-1 mg-1 protein) by hydrolysis of the Gln6-Phe7, Phe7-Phe8 and Gly9-Leu10 bonds, which is identical to the cleavage of SP by purified endopeptidase-24.11. The C-terminal cleavage of GRP10 and SP would inactivate the peptides. It is concluded that a membrane-bound peptidase in the stomach wall catabolizes and inactivates GRP10 and SP and that, in its specificity and sensitivity to phosphoramidon, this peptidase resembles endopeptidase-24.11.
Assuntos
Hormônios Gastrointestinais/metabolismo , Peptídeo Hidrolases/metabolismo , Peptídeos/metabolismo , Estômago/enzimologia , Substância P/metabolismo , Animais , Membrana Celular/enzimologia , Peptídeo Liberador de Gastrina , Glicopeptídeos/farmacologia , Cinética , Inibidores de Proteases/farmacologia , Substância P/análogos & derivados , Especificidade por Substrato , SuínosRESUMO
The purpose of this investigation was to examine the pathway of substance P (SP) and neurotensin (NT) catabolism in the gastric wall of the rat and identify some of the enzymes involved. Under anaesthesia an infusion catheter and a bundle of dialysis fibres were implanted into the stomach wall of the rat. Experiments commenced on conscious rats 2 days after surgery. In control experiments [3H]-SP(Pro-2,4) or [3H]-NT(Tyr-3,11) were injected into gastric tissues through the catheter and catabolites were collected in the dialysis fibres and separated by high pressure liquid chromatography. In other studies captopril, MK422 (inhibitors of angiotensin converting enzyme) or phosphoramidon (an inhibitor of endopeptidase-24.11, 'enkephalinase') were injected into gastric tissues before the peptide label. SP1-11 was degraded to mainly SP1-2, SP3-4 with some SP1-6, SP1-7 and SP1-8. Catabolism was partially but significantly (5% level) inhibited by MK422 and captopril, but not by phosphoramidon. NT1-13 was degraded to NT1-8, NT9-13, NT1-11 and NT1-12. NT catabolism was partially but significantly (5% level) inhibited by MK422. It is concluded that an enzyme resembling angiotensin converting enzyme is involved in the initial stages of SP and NT catabolism in the rat stomach. The involvement of other peptidases cannot be excluded because inhibition of breakdown was not complete.
Assuntos
Inibidores da Enzima Conversora de Angiotensina , Captopril/farmacologia , Enalapril/análogos & derivados , Mucosa Gástrica/metabolismo , Glicopeptídeos/farmacologia , Neurotensina/metabolismo , Substância P/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Enalapril/farmacologia , Enalaprilato , Cinética , Masculino , Fragmentos de Peptídeos/análise , Ratos , Ratos Endogâmicos , Termolisina/antagonistas & inibidoresRESUMO
BACKGROUND: Intractable ascites, refractory to medical therapy, occurs in approximately 10 percent of patients with ascites from cirrhosis and is almost always fatal. Sinusoidal hypertension resulting from hepatic venous outflow obstruction plays a primary role in the pathogenesis of cirrhotic ascites and provides the rationale for decompression of the liver by side-to-side portacaval shunt in treatment of intractable ascites. This report presents the experimental basis for the use of side-to-side shunt and long-term results of a prospective study in 34 selected patients with intractable cirrhotic ascites. STUDY DESIGN: In the experimental studies, hepatic venous outflow obstruction and massive ascites were produced in dogs by ligation of the hepatic veins, and the effect of portacaval shunts on ascites, thoracic duct lymph flow, and aldosterone secretion were measured. In the clinical study, 34 carefully selected patients with cirrhosis (91 percent alcoholic) and truly intractable ascites (failure of medical therapy for 5 to 24 months) underwent side-to-side portacaval shunt. The effects on ascites, survival, metabolic abnormalities, and quality of life were studied prospectively during follow-up that was longer than 5 years in all but two patients. Quantitative Child's risk classes in percent of patients were A in 0, B in 68, and C in 32. RESULTS: In the experimental studies, side-to-side portacaval shunt permanently relieved severe ascites, reduced the 13-fold increase in thoracic duct lymph flow rate to almost normal, and abolished the aldosterone hypersecretory response to minimal hepatic venous outflow obstruction. End-to-side portacaval shunt was much less effective. In the clinical study, side-to-side portacaval shunt reduced mean portal vein-inferior vena cava pressure gradient from 282 mm saline to 4 mm and permanently relieved all patients of ascites without subsequent requirement of diuretic therapy. Two patients who died of hepatoma, and one who died of heart failure developed terminal ascites. Thirty-day mortality rate was 6 percent, and long-term survival rates at 5, 10, and 15 years were 75 percent, 74 percent, and 73 percent. In metabolic studies, side-to-side shunt produced marked diuresis and natriuresis and abolished hypersecretion of aldosterone. Quality of life was generally improved as a result of a low incidence of recurrent portal-systemic encephalopathy (6 percent), abstinence from alcohol in 91 percent, improvement in liver function in 81 percent, and improvement in Child's risk class. The portacaval anastomosis remained permanently patent in every patient. CONCLUSIONS: Side-to-side portacaval shunt is very effective treatment of intractable ascites from cirrhosis. Our results are attributable to careful selection of patients, an organized system of care, and a program of rigorous, lifelong follow-up that emphasizes abstinence from alcohol and dietary protein restriction.
Assuntos
Ascite/cirurgia , Cirrose Hepática Experimental/cirurgia , Cirrose Hepática/cirurgia , Derivação Portocava Cirúrgica/métodos , Adulto , Animais , Ascite/mortalidade , Ascite/fisiopatologia , Diurese , Cães , Feminino , Humanos , Cirrose Hepática/mortalidade , Cirrose Hepática/fisiopatologia , Masculino , Pessoa de Meia-Idade , Natriurese , Estudos Prospectivos , Qualidade de Vida , Taxa de Sobrevida , Resultado do TratamentoRESUMO
BACKGROUND: Emergency treatment of acute bleeding is of singular and paramount importance in the therapy of portal hypertension and esophagogastric varices. Accordingly, for more than three decades we have conducted prospective studies of emergency therapy, and particularly of emergency portacaval shunt (EPCS). STUDY DESIGN: Emergency portacaval shunt was performed upon 400 patients with cirrhosis of the liver and acutely bleeding esophagogastric varices according to three principles: operation within eight hours of initial contact; unselected patients, meaning that no patient with variceal bleeding caused by hepatic disease was excluded from EPCS, and prospective study, meaning that a well-defined protocol was consistently used and data were collected on-line. Patients were divided into an early group of 180 treated from 1963 to 1978 and a recent group of 220 treated from 1978 to July, 1990, with similar characteristics, but strikingly different outcome. Follow-up rates at one, five, and ten years were 100, 98, and 97 percent, respectively; 96 percent of patients underwent EPCS five or more years ago. Proof of acute variceal bleeding and of cirrhosis of the liver (alcoholic in 95 percent) was obtained in every patient. Child's risk classes determined quantitatively were A in 11 percent of the patients, B in 65 percent, and C in 24 percent. All patients had a direct portacaval shunt, side-to-side in 85 percent, which reduced the mean portal vein to inferior vena cava pressure gradient from 271 to 21 mm saline solution. RESULTS: All but four patients (99 percent) had immediate and permanent control of variceal bleeding. Thrombosis of the shunt occurred in only two patients (0.5 percent). Survival rates at 30 days, five years, ten years, and 15 years in the early group were 58, 40, 30, and 30 percent, respectively, while in the recent group they were 85, 78, 71, and 57 percent, respectively (p < 0.0001). Other striking gains in the recent group were abstention from alcohol, improvement in liver function and improvement in Child's class, all in 70 percent of patients. Recurrent portal-systemic encephalopathy occurred in 9 percent of the early group and 8 percent of the recent group. CONCLUSIONS: Emergency portacaval shunt substantially improved survival and quality of life of patients with cirrhosis of the liver and bleeding varices. Our results are attributable to rapid and simplified diagnosis, prompt operation, an organized system of care, and rigorous, lifelong follow-up evaluation that emphasized abstinence from alcohol and dietary protein control. Transplantation of the liver is infrequently required in patients whose bleeding is permanently controlled.
Assuntos
Varizes Esofágicas e Gástricas/cirurgia , Hemorragia Gastrointestinal/cirurgia , Cirrose Hepática Alcoólica/complicações , Derivação Portocava Cirúrgica , Adulto , Idoso , Pressão Sanguínea/fisiologia , Emergências , Varizes Esofágicas e Gástricas/prevenção & controle , Feminino , Seguimentos , Hemorragia Gastrointestinal/prevenção & controle , Encefalopatia Hepática/etiologia , Humanos , Hipertensão Portal/complicações , Hipertensão Portal/fisiopatologia , Cirrose Hepática Alcoólica/fisiopatologia , Masculino , Pessoa de Meia-Idade , Derivação Portocava Cirúrgica/efeitos adversos , Derivação Portocava Cirúrgica/métodos , Veia Porta/fisiopatologia , Estudos Prospectivos , Qualidade de Vida , Recidiva , Taxa de Sobrevida , Temperança , Resultado do Tratamento , Veia Cava Inferior/fisiopatologiaRESUMO
Organized thrombus in the main trunk of the portal vein was encountered in 85 (6.5%) of 1300 patients with cirrhosis and variceal hemorrhage who underwent direct portacaval shunt (PCS). The thrombus was successfully removed with restoration of portal blood flow in all patients by phlebothrombectomy and balloon catheter extraction. Of the 85 patients, 65 were among 400 unselected patients who underwent emergency PCS (16%), and 20 were among 900 selected patients who underwent elective PCS (2%). All patients were closely followed for at least 5 years. Patients with portal vein thrombosis (PVT) had more advanced liver disease than those without PVT, reflected preoperatively in significantly higher (P < 0.01) incidences of ascites (75%), severe muscle wasting (52%), varices of very large size (94%), the hyperdynamic state (94%), severe hypersplenism with a platelet count of less than 50,000/mm3 (92%), and placement in Child's class C (52%). Side-to-side PCS reduced the portal vein-inferior vena cava pressure gradient to a mean of 23 mm saline solution in patients with PVT, similar to the marked pressure reduction obtained in patients without PVT. PCS promptly stopped variceal bleeding in all patients in the emergency PCS group. Permanent prevention of recurrent variceal bleeding was successful in 95% of patients with PVT and more than 99% of patients without PVT. Survival rates were similar in patients with and without PVT. In patients with PVT, survival rates at 30 days and 1, 5, 10, and 15 years following emergency PCS were 69%, 66%, 65%, 55%, and 51%, respectively, and following elective PCS were 95%, 90%, 70%, 65%, and 60%, respectively. Quality of life was similar in patients with and without PVT. Long-term PCS patency was demonstrated yearly in 93% of patients in the group with PVT and in 99.7% of patients without PVT. Other similarities after 5 years between patients with and without PVT, respectively, were the incidences of recurrent encephalopathy (9% vs. 8%), alcohol abstinence (61% vs. 64%), improved liver function (68% vs. 62% to 75%), and return to work (52% vs. 56% to 64%). It was concluded that in patients with cirrhosis and variceal hemorrhage it is almost always possible to remove portal vein thrombus by means of phlebothrombectomy and then perform a direct PCS with results similar to those achieved in the absence of PVT.
Assuntos
Varizes Esofágicas e Gástricas/complicações , Hemorragia Gastrointestinal/complicações , Cirrose Hepática/complicações , Veia Porta , Trombose/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Varizes Esofágicas e Gástricas/cirurgia , Feminino , Hemorragia Gastrointestinal/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Derivação Portocava Cirúrgica , Estudos ProspectivosRESUMO
The aim of this study was to examine the catabolism of substance P (SP) in the stomach wall of the rat. Catabolism in vitro was investigated by incubation of unlabelled and tritiated SP (prolyl 2,4-3,4(n)-3H SP) with membrane bound-peptidases prepared from the rat gastric corpus. Catabolism was studied in vivo by use of a catheter chronically implanted in the stomach wall to deliver tritiated SP to the gastric tissues and implanted dialysis fibers to collect the catabolic products. The products from both experiments were separated by high pressure liquid chromatography and identified by their retention times or amino acid analysis. Membrane-bound peptidases in vitro hydrolyzed both unlabelled and tritiated SP and the products of hydrolysis were consistent with the cleavage of three bonds: Gln6-Phe7, Phe7-Phe8 and Gly9-Leu10. None of the peptide fragments would be expected to be biologically active. Only those fragments with tritiated Pro residues could be detected in vivo. The major identified products were SP(1-2) and SP(3-4), with smaller amounts of SP(1-4), SP(1-6), SP(1-7), SP(1-8) and SP(1-9). The enzymes that may be responsible for these cleavage patterns are discussed.
Assuntos
Estômago/enzimologia , Substância P/metabolismo , Aminoácidos/análise , Animais , Cromatografia Líquida de Alta Pressão , Dipeptidil Peptidase 4 , Dipeptidil Peptidases e Tripeptidil Peptidases/metabolismo , Endopeptidases/metabolismo , Ratos , Ratos EndogâmicosRESUMO
The aim of this study was to examine the distribution of dopamine and norepinephrine in the proximal alimentary tract of the rat and to assess the contributions of sympathetic and vagal fibers to the tissue concentrations of both catecholamines. Tissues were extracted in perchloric acid and the catecholamines were separated by high pressure liquid chromatography and detected electrochemically. In untreated rats (controls) both catecholamines were concentrated in the gastric muscle but norepinephrine levels were 6-8 times higher (corpus, dopamine 35 +/- 7 ng . g-1, norepinephrine 265 +/- 50 ng . g-1, mean +/- SE, n = 6). In the mucosa norepinephrine concentrations were 10-12 times higher (corpus, dopamine 12 +/- 3 ng . g-1, norepinephrine 140 +/- 26 ng . g-1). Chemical sympathectomy (6 hydroxydopamine, 100 mg . kg-1 ip 3 days) significantly reduced dopamine concentrations in muscle and norepinephrine in muscle, mucosa, pylorus and duodenum. In all tissues the effects on norepinephrine were greater. Surgical vagotomy significantly reduced dopamine concentrations in the gastric muscle, but not the mucosa. Norepinephrine concentrations in the stomach of vagotomized rats were significantly reduced only in the pylorus. Differences in the relative concentrations of dopamine and norepinephrine in gastric tissues of the normal rat and differences in the effects of sympathectomy and vagotomy suggest that dopamine and norepinephrine exist, to an extent, in separate populations of cells and that dopamine is not merely a precursor of norepinephrine. Gastric mucosal dopamine, which was mainly unaffected by either treatment, may exist in APUD cells.