RESUMO
We identified 100 scientific questions that, if answered, would have the greatest impact on conservation practice and policy. Representatives from 21 international organizations, regional sections and working groups of the Society for Conservation Biology, and 12 academics, from all continents except Antarctica, compiled 2291 questions of relevance to conservation of biological diversity worldwide. The questions were gathered from 761 individuals through workshops, email requests, and discussions. Voting by email to short-list questions, followed by a 2-day workshop, was used to derive the final list of 100 questions. Most of the final questions were derived through a process of modification and combination as the workshop progressed. The questions are divided into 12 sections: ecosystem functions and services, climate change, technological change, protected areas, ecosystem management and restoration, terrestrial ecosystems, marine ecosystems, freshwater ecosystems, species management, organizational systems and processes, societal context and change, and impacts of conservation interventions. We anticipate that these questions will help identify new directions for researchers and assist funders in directing funds.
Assuntos
Biodiversidade , Mudança Climática , Conservação dos Recursos Naturais/métodos , Ecologia/métodos , Recuperação e Remediação Ambiental/métodos , Pesquisa/tendências , Organizações sem Fins Lucrativos , Meio Social , Especificidade da EspécieRESUMO
Sporadic, non-familial Parkinson's disease is characterized by a 15-30% reduction in complex I activity of the electron transport chain. A pharmacological model of reduced complex I activity was created by prolonged treatment of SH-SY5Y cells with low doses (5-20 nM) of rotenone, a selective inhibitor of complex I. Short-term (less than 2 week) exposure to rotenone did not influence calcium signaling, production of reactive oxygen species, or mitochondrial morphology. However, following 2 weeks of rotenone exposure, SH-SY5Y cells showed unusual calcium dynamics, specifically multiple calcium responses to carbachol, a muscarinic agonist. These secondary calcium responses were not seen in control SH-SY5Y cells and were dependent upon calcium influx. Mitochondrial membrane potential was also reduced in low dose rotenone-treated cells. These results demonstrate that a chronic, partial reduction in complex I activity, such as that seen in Parkinson's disease, can alter cell signaling events and perhaps increase the susceptibility of cells to calcium overload and subsequent cell death.
Assuntos
Sinalização do Cálcio/fisiologia , Mitocôndrias/enzimologia , NADH NADPH Oxirredutases/metabolismo , Doença de Parkinson/enzimologia , Células Tumorais Cultivadas/enzimologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Morte Celular/fisiologia , Complexo I de Transporte de Elétrons , Humanos , Mitocôndrias/efeitos dos fármacos , Modelos Biológicos , NADH NADPH Oxirredutases/efeitos dos fármacos , Degeneração Neural/enzimologia , Degeneração Neural/fisiopatologia , Neuroblastoma , Doença de Parkinson/fisiopatologia , Espécies Reativas de Oxigênio/metabolismo , Rotenona/farmacologia , Células Tumorais Cultivadas/efeitos dos fármacos , Desacopladores/farmacologiaRESUMO
To study the regulation of striatal acetylcholine (ACH) release, adult male rat striata were dissociated and incubated with 3H-choline to synthesize 3H-ACH. Fractional 3H-ACH efflux per min during continuous perifusion was: (1) tightly regulated; (2) dependent on calcium influx; (3) stimulated by 10 mM K+ and 1 mM glutamate; and (4) comparable to ACH release detected by HPLC. Thus, acutely dissociated striata exhibit calcium-sensitive, voltage-dependent secretion of 3H-ACH and direct receptor-mediated stimulation of release through the glutamate receptor family. This new approach toward cholinergic secretory physiology will help clarify complex striatal circuitry.
Assuntos
Acetilcolina/metabolismo , Corpo Estriado/metabolismo , Animais , Cálcio/metabolismo , Cromatografia Líquida de Alta Pressão , Corpo Estriado/citologia , Ácido Glutâmico/farmacologia , Masculino , Potássio/farmacologia , RatosRESUMO
Fractional release of [3H]ACh was evaluated under basal and evoked conditions in striatal slices from normal and acutely dopamine-depleted adult rats for the influence of D1- and D2-DA receptor agonists. The D1 ligand had no effect on normal slices but DA depletion unmasked two independent but simultaneous supersensitive responses: augmentation of K(+)-evoked and inhibition of glutamate-evoked release. The D2 ligand inhibited evoked release in normal slices and this effect was not potentiated. This is a new cholinergic model of acute D1 receptor supersensitivity.
Assuntos
Acetilcolina/metabolismo , Dopamina/fisiologia , Neostriado/metabolismo , Receptores de Dopamina D1/fisiologia , Animais , Antipsicóticos/farmacologia , Agonistas de Dopamina/farmacologia , Inibidores Enzimáticos/farmacologia , Ácido Glutâmico/farmacologia , Técnicas In Vitro , Masculino , Metiltirosinas/farmacologia , Neostriado/efeitos dos fármacos , Ratos , Receptores de Dopamina D1/agonistas , Reserpina/farmacologia , Tirosina 3-Mono-Oxigenase/antagonistas & inibidores , alfa-MetiltirosinaRESUMO
Dithizone (DTZ) is a recognized diabetogenic agent in vivo, and a supravital stain commonly used for identification of islets to be used for transplantation. In the present studies, we compared DTZ staining of freshly isolated and cultured canine, bovine, and porcine islets, and the effect of DTZ on the function and viability of islets. Incubation with DTZ resulted in staining of canine and porcine islets, but no discernible staining with bovine islets. Insulin content of porcine, canine, and bovine islet was 2.0 +/- 0.2, 2.2 +/- 0.3, and 1.9 +/- 0.2 mU/EIN, indicating a lack of correspondence of DTZ staining and insulin content. Seven days of culture with canine islets resulted in > or = 50% reduction of DTZ stained cells. Exposure to DTZ at 50 micrograms/mL resulted in a maximal number of stained cells in preparations of purified islets (80-85%; counted after dispersion), a lower percentage of cells stained faintly at 20 micrograms/mL (50-55%), with no discernible staining at 10 micrograms/mL. Prolonged exposure of islets (4-48 h) to 20 micrograms/mL DTZ led to reduced insulin secretion and islet cell death. Incubation of canine or porcine islets with 100 micrograms/mL of DTZ for 0.5 h resulted in a dramatic loss of viability and diminished insulin secretory function, which was not reversed with continued culture. The concentration dependence of toxic effects paralleled the concentration dependence of cellular staining. The minimally effective staining concentration (20 micrograms/mL) also resulted in a loss of viability. An additional assessment of DTZ toxicity was made using the RIN-38 beta-cell line, which shows no discernible staining with DTZ.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ditizona/toxicidade , Ilhotas Pancreáticas/efeitos dos fármacos , Animais , Antimicina A/análogos & derivados , Antimicina A/farmacologia , Bovinos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cães , Relação Dose-Resposta a Droga , Glucose/farmacologia , Técnicas In Vitro , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/fisiopatologia , Coloração e Rotulagem , SuínosRESUMO
We report the successful application of a hybrid artificial pancreas device for the treatment of severe diabetes mellitus induced by total pancreatectomy in two dogs. Control of the blood sugar was achieved for more than 1 year in these two animals without any immunosuppressive therapy. Although exogenous insulin was required therapy. Although exogenous insulin was required during the latter part of the study period, removal of the devices resulted in a rapid increase in the fasting blood sugar levels and the exogenous insulin requirements (P < 0.001 versus weeks 1-52 in both dogs). Metabolic studies, postexplant in vitro studies, and histologic analyses confirmed islet cell survival and insulin production by the devices. This hybrid artificial pancreas has a clear clinical potential for islet cell transplantation without immunosuppression.
Assuntos
Diabetes Mellitus Experimental/terapia , Sistemas de Infusão de Insulina , Animais , Glicemia/análise , Cães , Jejum , Feminino , Teste de Tolerância a Glucose , Pancreatectomia , Fatores de TempoAssuntos
Glicemia/metabolismo , Diabetes Mellitus Experimental/cirurgia , Sistemas de Infusão de Insulina , Transplante das Ilhotas Pancreáticas/métodos , Análise de Variância , Animais , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/tratamento farmacológico , Cães , Feminino , Teste de Tolerância a Glucose , Insulina/uso terapêutico , Pancreatectomia , Fatores de Tempo , Transplante HomólogoAssuntos
Diabetes Mellitus Experimental/imunologia , Sobrevivência de Enxerto/imunologia , Transplante das Ilhotas Pancreáticas/imunologia , Membranas Artificiais , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 1/imunologia , Cultura em Câmaras de Difusão , Cães , Feminino , Insulina/metabolismo , Secreção de Insulina , Ratos , Ratos Endogâmicos BB , Ratos Endogâmicos Lew , Transplante Heterólogo/imunologiaRESUMO
Extended survival of canine islet xenografts implanted in spontaneously diabetic BB/Wor rats has been achieved by islet encapsulation inside cylindrical chambers fabricated from permselective acrylic membranes. Intraperitoneal implantation of the encapsulated islets reversed the diabetic state of the 10 recipients within 24 h. Plasma glucose levels declined from a preimplantation level of 459 +/- 30 to 102 +/- 14 mg/dl during the first 10 days. All of the animals sustained these levels for at least 1 month, and 2 animals for at least 2 and 8 months, respectively. To confirm that glucose homeostasis resulted from the encapsulated islet grafts, the implants were removed from 2 rats 1 month postimplantation, whereas a third was removed at 2 months. Hyperglycemia was observed immediately in all 3 animals, with glucose levels rising from 100 +/- 3 to 510 +/- 43 mg/dl within 1 day. In contrast, diabetic control rats (n = 4) receiving nonencapsulated islets became hyperglycemic in less than 1 week. The iv glucose tolerance test K value (decline in glucose levels, percent per min) at 10 days was 2.3 +/- 0.4 compared with 0.6 +/- 0.1 (P less than 0.005) and 3.1 +/- 0.1 (P less than 0.02) for untreated diabetic (n = 4) and normal control (n = 4) groups. Histological analyses and electron microscopy of long term functioning grafts revealed well preserved islets, with hormone-producing alpha-, beta-, and delta-cells; the membranes were generally free of fibrosis and host cell adherence. These results demonstrate that permselective artificial membranes can protect discordant islet xenografts from both graft rejection and autoimmune destruction for more than 1 month in an animal model that is similar in several respects to human type I diabetes.
Assuntos
Diabetes Mellitus Tipo 1/cirurgia , Terapia de Imunossupressão , Transplante das Ilhotas Pancreáticas/métodos , Animais , Glicemia/metabolismo , Peso Corporal , Glucagon/análise , Teste de Tolerância a Glucose , Técnicas Imunoenzimáticas , Ilhotas Pancreáticas/química , Ilhotas Pancreáticas/ultraestrutura , Masculino , Membranas Artificiais , Microscopia Eletrônica , Ratos , Ratos Endogâmicos BB , Somatostatina/análiseRESUMO
The use of a selectively permeable membrane to transplant nonsyngeneic tissue without accompanying immunosuppressive therapy has been investigated using two approaches. The first hybrid artificial pancreas is implanted as a vascular shunt in which blood circulates through the lumen of a tubular membrane. The islet tissue is distributed within a chamber surrounding the membrane enclosed by an acrylic housing. Studies with diabetic dogs that have had pancreatectomies have demonstrated that these devices could replace exogenous insulin therapy for at least 6 months in five animals. This report presents data on two of these dogs, demonstrating viability and function of the transplanted tissue after 1 year. As an alternative to the vascular device, islets sealed within cylindrical permselective membrane chambers have been implanted in the peritoneum. Preliminary data from three dogs indicate that the nonvascular implants can also regulate fasting glucose levels in the diabetic dog model.
Assuntos
Sistemas de Infusão de Insulina , Transplante das Ilhotas Pancreáticas/métodos , Animais , Glicemia/metabolismo , Cães , Estudos de Avaliação como Assunto , Feminino , Insulina/administração & dosagem , Membranas Artificiais , Pancreatectomia , PermeabilidadeRESUMO
Long-term survival of dog islet allografts implanted in diabetic pancreatectomized dogs was achieved by islet encapsulation inside cylindrical chambers fabricated from permselective acrylic membranes (nominal M(r) exclusion of 50,000-80,000). Dog islets were isolated from the pancreases of outbred mongrel dogs by collagenase digestion. Chambers containing mean +/- SE 316 +/- 63K islet equivalents (mean islet volume, 558 +/- 111 mm3, purity 90-95%) were peritoneally implanted into six totally pancreatectomized dogs. The dogs were monitored for glycemic control by fasting and postprandial blood glucose determinations, and responses to both intravenous glucose (intravenous glucose tolerance test 0.5 g/kg) and oral glucose (oral glucose tolerance test 1 g/kg). All of the dogs required appreciably lower dosages of exogenous insulin therapy for control of fasting blood glucose levels, with the mean daily insulin dose dropping from 38 +/- 7 to 5 +/- 1 U/day during the 1st wk. Three recipients required no insulin for greater than 82, greater than 68, and 51 days. Intravenous glucose tolerance test K values (decline in glucose levels, %/min) at 1 and 2 mo postimplantation were 2.7 +/- 0.4 and 2.0 +/- 0.5, respectively compared with 3.5 +/- 0.5 before pancreatectomy. The glucose values during oral glucose tolerance tests at 2 wk, although returning to less than 125 mg/dl (less than 7.0 mM) by 2 h, exceeded the normal range, with peak values of 174 to 202 mg/dl (9.7 to 11.3 mM). These preliminary results are encouraging, and represent an important step in determining the feasibility of using this type of diffusion-based hybrid artificial pancreas as treatment for diabetes mellitus in humans.
Assuntos
Diabetes Mellitus Experimental/cirurgia , Transplante das Ilhotas Pancreáticas , Animais , Glicemia/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Cães , Feminino , Teste de Tolerância a Glucose , Insulina/uso terapêutico , Transplante das Ilhotas Pancreáticas/métodos , Transplante das Ilhotas Pancreáticas/fisiologia , Masculino , Pancreatectomia , Transplante HomólogoAssuntos
Sistemas de Infusão de Insulina , Transplante das Ilhotas Pancreáticas/métodos , Ilhotas Pancreáticas/metabolismo , Animais , Glicemia/metabolismo , Separação Celular , Células Cultivadas , Diabetes Mellitus Experimental/cirurgia , Cães , Feminino , Bombas de Infusão Implantáveis , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/citologia , PancreatectomiaAssuntos
Transplante das Ilhotas Pancreáticas , Ilhotas Pancreáticas/metabolismo , Transplante Heterólogo , Animais , Animais Recém-Nascidos , Bovinos , Separação Celular/métodos , Células Cultivadas , Centrifugação Zonal/métodos , Glucose/farmacologia , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacosAssuntos
Diabetes Mellitus Experimental/cirurgia , Transplante das Ilhotas Pancreáticas/métodos , Animais , Glicemia/metabolismo , Peso Corporal , Bovinos , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/tratamento farmacológico , Cães , Feminino , Sistemas de Infusão de Insulina , Insulina de Ação Prolongada/uso terapêutico , Transplante das Ilhotas Pancreáticas/fisiologia , Pancreatectomia , Transplante Heterólogo/métodos , Transplante Heterólogo/fisiologiaAssuntos
Diabetes Mellitus Experimental/cirurgia , Transplante das Ilhotas Pancreáticas/métodos , Transplante Heterólogo/métodos , Alginatos , Análise de Variância , Animais , Glicemia/metabolismo , Bovinos , Separação Celular , Diabetes Mellitus Experimental/sangue , Cães , Ácido Glucurônico , Ácidos Hexurônicos , Sistemas de Infusão de Insulina , Ilhotas Pancreáticas/citologia , Transplante das Ilhotas Pancreáticas/patologia , Transplante das Ilhotas Pancreáticas/fisiologia , Membranas Artificiais , Ratos , Ratos Endogâmicos Lew , Suínos , Transplante Heterólogo/patologia , Transplante Heterólogo/fisiologiaRESUMO
Immunoisolation of nonsyngeneic tissue using a selectively permeable membrane is designed to facilitate transplantation without the use of immunosuppression. The authors' studies have evaluated a hybrid artificial pancreas device that is implanted as an arteriovenous vascular shunt. Devices containing allogeneic or xenogeneic islets were implanted in diabetic dogs who had undergone pancreatectomies, and the devices eliminated the requirement for exogenous insulin for control of fasting glycemia in 11 animals for periods ranging from 1 to 8 months. Furthermore, unseeded devices in normal dogs have been shown to remain patent for over 2 years with low doses of aspirin as the only anticoagulant. These results indicate that this approach has potential as a therapy for diabetes.
Assuntos
Diabetes Mellitus Experimental/terapia , Sistemas de Infusão de Insulina , Transplante das Ilhotas Pancreáticas/métodos , Animais , Glicemia/metabolismo , Cães , Desenho de Equipamento , Estudos de Avaliação como Assunto , Feminino , Membranas Artificiais , Pancreatectomia , Fatores de TempoRESUMO
Permselective acrylic membranes were employed to prevent immune rejection of discordant islet xenografts isolated from various large animals. Canine, porcine, and bovine islets were seeded into tubular diffusion chambers and transplanted into the peritoneum of 27 nonimmunosuppressed streptozotocin-induced diabetic Lewis rats. Six recipients received islet grafts from bovine calves, 7 received grafts from pigs, and 14 received grafts from dogs. Four of the latter were removed at 1 month. In the control group of 10 diabetic rats, 4 received nonencapsulated canine islets, 3 received nonencapsulated bovine islets, and 3 received nonencapsulated porcine islets. Recipients of encapsulated islets promptly dropped from a pretransplantation plasma glucose level of 487 +/- 36 (mean +/- SEM) to 84 +/- 2 (canine), 81 +/- 4 (bovine), and 81 +/- 3 mg/dl (porcine) during the first week. All of the animals sustained these levels for at least 1 month. One rat spontaneously reverted to diabetes at 54 days posttransplantation; 4 other rats became hyperglycemic (glucose, greater than 600 mg/dl) after membrane removal on day 30. The remaining 22 rats maintained fasting euglycemia for greater than 10 weeks. In contrast, rats that received nonencapsulated islets became hyperglycemic in less than 7 days. Intravenous glucose tolerance test K values (decline in glucose levels, %/min) at 1 month for the canine and bovine encapsulated islet transplant group were 3.5 +/- 0.3 and 3.3 +/- 0.1 compared with 3.3 +/- 0.1 (P = 0.63) and 0.91 +/- 0.1 (P less than 0.0001) for normal (n = 4) and diabetic (n = 4) control groups. Morphologic studies of long-term functioning grafts (30-130 days) revealed well-preserved alpha, beta, and delta cells, with varying degrees of granulation. These results demonstrate that immune isolation of islet tissue using permselective artificial membranes can protect discordant islet xenografts from immune rejection in the absence of any immunosuppressive drugs.
Assuntos
Diabetes Mellitus Experimental/cirurgia , Transplante das Ilhotas Pancreáticas/fisiologia , Transplante Heterólogo/fisiologia , Análise de Variância , Animais , Glicemia/metabolismo , Bovinos , Diabetes Mellitus Experimental/sangue , Cães , Glucose/farmacologia , Técnicas Imunoenzimáticas , Terapia de Imunossupressão , Insulina/análise , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Transplante das Ilhotas Pancreáticas/imunologia , Ratos , Ratos Endogâmicos Lew , Suínos , Transplante Heterólogo/imunologiaRESUMO
Previously the authors reported on a Hybrid Artificial Pancreas device that maintained patent vascular anastomoses in normal dogs and, when seeded with allogeneic canine islets, maintained normal fasting blood sugars (FBS) in diabetic pancreatectomized dogs. Eventual failure of these devices was believed to be related to loss of islet viability and/or insufficient islet mass. The current study evaluates the effect of increased islet mass produced by implantation of two islet-seeded devices in pancreatectomized dogs and compares the results with those from dogs that received a single device. Twelve of fifteen dogs receiving single devices showed initial function as determined by elimination or reduction of exogenous insulin requirement; four showed initial function and seven showed extended function (100 to 284 days). Excessive weight loss (more than 20%), despite normal FBS and insulin dependence, required that four animals in this latter group be killed. Devices seeded with xenogeneic islets have met with limited success. One dog that received two bovine islet-seeded devices achieved function for more than 100 days; the remaining bovine-seeded devices (n = 8) functioned for only 3 to 16 days. Porcine islet-seeded devices were assessed by intravenous glucose tolerance tests (IVGTT). Recipients of two devices seeded with allogeneic islets demonstrated improved IVGTT results when compared to those from pancreatectomized dogs and recipients of single devices but were abnormal when compared to intact animals. Histologic examination of device and autopsy material from all failed experiments was performed and showed no mononuclear cell infiltration of the islet chamber or vascular graft material, only a few incidence of device thrombosis, and varying degrees of islet viability as judged by morphologic and immunohistochemical evaluation. The authors believe they have demonstrated progress toward the development and clinical applicability of the Hybrid Artificial Pancreas.
Assuntos
Diabetes Mellitus Tipo 1/cirurgia , Insulina/administração & dosagem , Transplante das Ilhotas Pancreáticas/instrumentação , Próteses e Implantes , Animais , Glicemia/análise , Peso Corporal , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/metabolismo , Cães , Falha de Equipamento , Seguimentos , Teste de Tolerância a Glucose , Transplante das Ilhotas Pancreáticas/mortalidade , Transplante das Ilhotas Pancreáticas/patologia , Transplante das Ilhotas Pancreáticas/fisiologia , Pancreatectomia , Transplante Heterólogo , Transplante HomólogoRESUMO
Diabetic complications such as neuropathy, retinopathy, and renal and cardiovascular disease continue to pose major health risks for diabetic patients. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. The biohybrid perfused artificial pancreas was designed to incorporate islet tissue and a selectively permeable membrane that isolates this tissue from the immune system of the recipient. Biohybrid pancreas devices containing canine islet allografts were implanted in ten pancreatectomized dogs requiring 18 to 32 units of injected insulin daily. These implants resulted in good control of fasting glucose levels in six of these animals without further exogenous insulin for periods of up to 5 months.