Endogenous Pancreatic Protease Activity and Methods for Impeding Their Function

Umeadi, C.; Bentsi-Barnes, K.; Kandeel, Fouad; Al-Abdullah, Ismail H.

doi:10.1016/j.transproceed.2008.01.033

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…Pefabloc, a serine protease inhibitor, is one commercial product that has been successfully used in animal and human islet isolations to decrease the measured activity of proteases (32), increase islet yield (33), and improve islet functional viability (34). Similarly, ulinastatin has also been shown to inhibit chymotrypsin and elastase activity during pancreas digestion (35). While protease activity has been beneficially decreased at the early stages of islet isolation, until this report, there has been a lack of information regarding the impact of TCE during islet culture, specifically impure islet culture.…”

Section: Discussionmentioning

confidence: 99%

Insulin Degradation by Acinar Cell Proteases Creates a Dysfunctional Environment for Human Islets Before/After Transplantation: Benefits of α-1 Antitrypsin Treatment

et al. 2011

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Background Pancreatic acinar cells are commonly co-transplanted along with islets during auto-and allo-transplantations. The aims of this study were to identify how acinar cell proteases cause human islet cell loss before and after transplantation of impure islet preparations and to prevent islet loss and function with supplementation of alpha-1 antitrypsin (A1AT). Methods Acinar cell protease activity, insulin levels, and percent islet loss were measured after culture of pure and impure clinical islet preparations. The effect of proteases on ultra-structure of islets and beta cell insulin granules were examined by transmission electron microscopy (TEM). The number of insulin granules and insulin-labeled immune-gold particles were counted. The in vivo effect of proteases on islet function was studied by transplanting acinar cells adjacent to islet grafts in diabetic mice. The effects of A1AT culture supplementation on protease activity, insulin levels, and islet function were assessed in pure and impure islets. Results Islet loss after culture was significantly higher in impure relative to pure preparations (30 vs. 14%, p<0.04). Lower islet purity was associated with increased protease activity and decreased insulin levels in culture supernatants. Reduced beta cell insulin granules and insulin degradation by proteases were confirmed by TEM. Transplantation results showed delayed islet graft function when acinar cells were transplanted adjacent to the islets under the kidney capsule. Supplementation of A1AT to impure islet cultures maintained islet mass, restored insulin levels, and preserved islet functional integrity. Conclusions Culture of impure islets in the presence of A1AT prevents insulin degradation and improves islet recovery.

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Section: Discussionmentioning

confidence: 99%

Insulin Degradation by Acinar Cell Proteases Creates a Dysfunctional Environment for Human Islets Before/After Transplantation: Benefits of α-1 Antitrypsin Treatment

et al. 2011

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“…The calculation of the percent inhibition was obtained by subtracting the experimental value (with inhibitor) from the control (without inhibitor), which results in a value that is divided by the control and multiplied by one hundred [58]. For all of the tested molecules, the higher the concentration, the higher the percentage of inhibition, this demonstrates a dose-dependent response ( Figure 3 The relevant activity of synthetic compounds is generally expressed by the IC 50 and SI toward the supporting host (Table 3).…”

Section: In Vitro Studiesmentioning

confidence: 99%

Discovery of antiviral molecules for dengue: In silico search and biological evaluation

Cabarcas-Montalvo

Maldonado-Rojas

Montes-Grajales

et al. 2016

European Journal of Medicinal Chemistry

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Background: Dengue disease is a global disease that has no effective treatment. The dengue virus (DENV) NS2B/NS3 protease complex is a target for designing specific antivirals due to its importance in viral replication and its high degree of conservation.Methods: NS2B/NS3 protease complex structural information was employed to find small molecules that are capable of inhibiting the activity of the enzyme complex. This inhibitory activity was probed with in vitro assays using a fluorescent substrate and the complex NS2B/NS3 obtained by recombinant DNA techniques, for testing the activity against dengue virus replication, HepG2 cells infected with dengue virus serotype 2 were used. Results: A total of 210,903 small molecules from PubChem were docked in silico to the NS2B/NS3 structure (PDB: 2FOM) to find molecules that were capable of inhibiting this protein complex. Five of the best 500 leading compounds, according to their affinity values (-11.6 and -13.5 kcal/mol), were purchased. The inhibitory protease activity on the recombinant protein and antiviral assays was tested. Conclusions: Chemicals CID54681617, CID54692801 and CID54715399 were strong inhibitors of NS2B/NS3, with IC 50 values (µM) and percentages of viral titer reductions of 19.9, 79.9%; 17.5, 69.8%; and 9.1, 73.9 %, respectively. Multivariate methods applied to the molecular descriptors showed two compounds that were structurally different from other DENV inhibitors. General significance: This discovery opens new possibilities for obtaining drug candidates against Dengue virus.

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“…Attempts to use Pefabloc during the isolation process instead of organ preservation phase have been made, showing that the Pefabloc can inhibit serine protease activity throughout the tissue digestion process; but, with controversial results on islet yield and function [94–96]. In addition, two research papers recently published by the same group show that when human islets were cultured or perifused with Pefabloc postisolation, insulin secretion of human islets in response to glucose stimulation was compromised, suggesting that the Pefabloc is not suitable for human islet isolation [97, 98]. …”

Section: Mitochondria and Mitoprotection In Islet Isolation And Cumentioning

confidence: 99%

Implication of Mitochondrial Cytoprotection in Human Islet Isolation and Transplantation

Wang

Mendoza-Elias

et al. 2012

Biochemistry Research International

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Islet transplantation is a promising therapy for type 1 diabetes mellitus; however, success rates in achieving both short- and long-term insulin independence are not consistent, due in part to inconsistent islet quality and quantity caused by the complex nature and multistep process of islet isolation and transplantation. Since the introduction of the Edmonton Protocol in 2000, more attention has been placed on preserving mitochondrial function as increasing evidences suggest that impaired mitochondrial integrity can adversely affect clinical outcomes. Some recent studies have demonstrated that it is possible to achieve islet cytoprotection by maintaining mitochondrial function and subsequently to improve islet transplantation outcomes. However, the benefits of mitoprotection in many cases are controversial and the underlying mechanisms are unclear. This article summarizes the recent progress associated with mitochondrial cytoprotection in each step of the islet isolation and transplantation process, as well as islet potency and viability assays based on the measurement of mitochondrial integrity. In addition, we briefly discuss immunosuppression side effects on islet graft function and how transplant site selection affects islet engraftment and clinical outcomes.

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Endogenous Pancreatic Protease Activity and Methods for Impeding Their Function

Cited by 3 publications

References 7 publications

Insulin Degradation by Acinar Cell Proteases Creates a Dysfunctional Environment for Human Islets Before/After Transplantation: Benefits of α-1 Antitrypsin Treatment

Insulin Degradation by Acinar Cell Proteases Creates a Dysfunctional Environment for Human Islets Before/After Transplantation: Benefits of α-1 Antitrypsin Treatment

Discovery of antiviral molecules for dengue: In silico search and biological evaluation

Implication of Mitochondrial Cytoprotection in Human Islet Isolation and Transplantation

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