Decellularized human pancreatic extracellular matrix-based physiomimetic microenvironment for human islet culture

A strategy that seeks to combine the biophysical properties of inert encapsulation materials like alginate with the biochemical niche provided by pancreatic extracellular matrix (ECM)-derived biomaterials, could provide a physiomimetic pancreatic microenvironment for maintaining long-term islet viability and function in culture. Herein, we have demonstrated that incorporating human pancreatic decellularized ECM within alginate microcapsules results in a significant increase in Glucose Stimulation Index (GSI) and total insulin secreted by encapsulated human islets, compared to free islets and islets encapsulated in only alginate. ECM supplementation also resulted in long-term (58 days) maintenance of GSI levels, similar to that observed in free islets at the first time point (day 5). At early time points in culture, ECM promoted gene expression changes through ECM- and cell adhesion-mediated pathways, while it demonstrated a mitochondria-protective effect in the long-term. STATEMENT OF SIGNIFICANCE: The islet isolation process can damage the islet extracellular matrix, resulting in loss of viability and function. We have recently developed a detergent-free, DI-water based method for decellularization of human pancreas to produce a potent solubilized ECM. This ECM was added to alginate for microencapsulation of human islets, which resulted in significantly higher stimulation index and total insulin production, compared to only alginate capsules and free islets, over long-term culture. Using ECM to preserve islet health and function can improve transplantation outcomes, as well as provide novel materials and platforms for studying islet biology in microfluidic, organ-on-a-chip, bioreactor and 3D bioprinted systems.

Size, Composition, and Support-Doping Effects on Oxygen Reduction Activity of Platinum-Alloy and on Non-platinum Metal-Decorated-Graphene Nanocatalysts

Recent investigations reported in the open literature concerning the functionalization of graphene as a support material for transition metal nanoparticle catalysts have examined isolated systems for their potential Oxygen Reduction Reaction (ORR) activity. In this work we present results which characterize the ability to use functionalized graphene (via dopants B, N) to upshift and downshift the adsorption energy of mono-atomic oxygen, O* (the ORR activity descriptor on ORR Volcano Plots), for various compositions of 4-atom, 7-atom, and 19-atom sub-nanometer binary alloy/intermetallic transition metal nanoparticle catalysts on graphene (TMNP-MDG). Our results show several important and interesting features: (1) that the combination of geometric and electronic effects makes development of simple linear mixing rules for size/composition difficult; (2) that the transition from 4- to 7- to 19-atom TMNP on MDG has pronounced effects on ORR activity for all compositions; (3) that the use of B and N as dopants to modulate the graphene-TMNP electronic structure interaction can cause shifts in the oxygen adsorption energy of 0.5 eV or more; (4) that it might be possible to make specific doped-graphene-Ni_xCu_y TMNP systems which fall close to the Volcano Peak for ORR. Our results point to systems which should be investigated experimentally and may improve the viability of future fuel cell or other ORR applications, and provide new paths for future investigations of more detail for TMNP-MDG screening.

P3842One-year efficacy and safety of prasugrel and ticagrelor in patients with Acute Coronary Syndromes: results from a prospective and multicenter ACHILLES Registry

Background

Prasugrel and Ticagrelor have demonstrated higher efficacy than clopidogrel in their main clinical trials for patients with Acute Coronary Syndrome (ACS). However, the long-term prognosis and different clinical characteristics related with the type of antiplatelet prescription in current clinical practice ACS patients have not been analyzed in depth.

Purpose

The objective of this study was to analyze the clinical profile of ACS and the efficacy and safety of new antiplatelet drugs (NAD) in current clinical practice patients discharged after an ACS.

Methods

We collected data from ACHILLES registry, and observational, prospective and multicenter registry of patients discharged after an ACS. We analyzed baseline characteristics, clinical profile and therapy during ACS admission and compared with the different treatments at discharge. After 1 year of follow-up, ischaemic and major bleeding events were analyzed. Multivariate Cox regression analysis and Kaplan Meier curves were also plotted.

Results

Of 1,717 consecutive patients, 1,294 (75.4%) were discharged with a P2Y12 inhibitor without oral anticoagulation. NAD was indicated in 47%. Patients treated with clopidogrel were elderly (69.1±13.4 vs. 60.4±11.5 years; p<0.001) and with a higher prevalence of cardiovascular risk factors. GRACE and CRUSADE score were higher in the clopidogrel than in NAD group (p<0.001). After 1 year of follow-up, 64 (5.0%/year) patients had a new myocardial infarction, 127 (10.0%/year) had a MACE and 78 (6.1%/year) patients died. Patients treated with clopidogrel had significantly higher annual rate of cardiovascular mortality, MACE and all cause-mortality (all of them p<0.001) without differences in major bleeding (p=0.587) compared with NAD therapy. After multivariate adjustment for the main clinical variables related with adverse prognosis in ACS patients, the discharge with NAD was independently associated with lower risk of all-cause mortality [HR 0.49, 95% CI (0.24–0.99); p=0.043] and lower risk of MACE [HR 0.65, 95% CI (0.43–0.99); p=0.049].

Event Free Survival according NAD Use

Conclusions

In this prospective, observational and current clinical practice ACS registry, the use of NAD was associated with a reduction of adverse events compared with clopidogrel in patients with ACS. NAD prescription at discharge was independently associated with lower all-cause mortality and MACE without differences in bleeding events. However, clopidogrel remained the most common P2Y12 inhibitor employed for ACS, especially in older and high risk population.

P3840Impact of potent P2Y12 inhibitors in adverse events reduction in diabetic patients with Acute Coronary Syndromes. An analysis from ACHILLES Registry

Background

Diabetic patients (DM) with an acute coronary syndrome (ACS) have a worse prognosis than non-diabetic patients. The new P2Y12 inhibitors, both ticagrelor and prasugrel, have shown efficacy in cardiovascular event reduction in patients with DM and ACS.

Purpose

The main objective of this study was to analyze the use of antiplatelet agents, prognosis and adverse events during the follow-up in diabetic patients admitted after an acute coronary syndrome.

Methods

These patients belong to ACHILLES registry. All patients with type 1 ACS were included prospectively in a national, prospective and multicenter registry. We analyzed baseline characteristics and comorbidities focusing on the presence of DM and the use of potent antiplatelet agents (ticagrelor and prasugrel) in those patients. After 1 year of follow-up, adverse events in diabetic patients were analyzed according to the type of antiplatelet used [clopidogrel vs new antiplatelet drugs (NAD)].

Results

Of 1,717 patients, 1,294 patients [mean age 65.0±13.3 years, 952 (73.6%) male] were finally analyzed (excluding patients discharged with oral anticoagulation). Diabetic patients had high prevalence of cardiovascular risk factors such as hypertension (54.9% vs 81.1%; p<0.001), dyslipidemia (50.7% vs 72.8%; p<0.001) or chronic kidney disease (22.1% vs 31.9%; p<0.001). Diabetic patients had also higher rate of non-invasive management of ACS compared to non-diabetic patients (4.5% vs 9.1%; p=0.002). At discharge, the use of NAD in patients with DM was 40.4% compared to 50.8% in non-diabetic patients (p<0.001).

After 1 year of follow-up, 64 (5.0%/year) patients had a new ACS, 46 (3.6%/year) patients died due to cardiovascular causes, 76 (6.1%/year) died for any cause and 28 (2.2%/year) patients had a major bleeding events. The use of clopidogrel in diabetic patients was associated with an increase in all-cause mortality [HR 2.90; 95% CI (1.27–6.629), p=0.011] and in MACE [HR 2.14; 95% CI (1.22–3.77), p=0.008.] Diabetic patients treated with NAD had no differences in terms of major bleeding but those patients presented a significant reduction in cardiovascular mortality and MACE with NAD use.

Event Free Survival according NAD Use

Conclusions

Patients with DM and ACS had high prevalence of concomitant cardiovascular risk factors but lower use of NAD compared with non-diabetic patients, despite DM patients had greater baseline risk. The use of NAD therapy was associated with a significant reduction in all-cause mortality, cardiovascular mortality and MACE without differences in major bleeding events.

P939Cardiovascular outcomes in patients with Acute Coronary Syndrome and previous cardiovascular disease. An analysis from ACHILLES Registry

Background

Patients with acute coronary syndrome (ACS) and previous cardiovascular disease (CVD) [stroke, peripheral arterial disease (PAD) or coronary artery disease (CAD)] are at high risk of serious events and mortality. Current clinical guidelines recommend new antiplatelet drugs (NAD) for high cardiovascular risk patients with ACS; however, these drugs are underused in different scenarios.

Purpose

The aim of this study was to analyze the use of NAD and advese events in patients with ACS an previous CVD.

Methods

ACHILLES registry is and observational, multicenter and prospective registry of ACS patients. 1717 ACS patients were consecutively included in this study from 3 tertiary Hospitals. Of them, 641 (37.33%) suffered from previous CVD: 149 patients with stroke, 154 patients with PAD and 541 patients with CAD. Bleeding, mortality and major adverse cardiac events (MACE) at 1 year of follow-up after hospital discharge were analyzed.

Results

NADs administration during hospital stay and at discharge was less frequent in patients with previous CVDs. Cox analysis in this cohort of patients showed that clopidogrel prescription at discharge was independently associated with MACEs [HR: 1.59 (95% CI 1.03–2.45); p=0.036] and with death [HR: 1.99 (95% CI 1.00–3.98); p=0.049] in multivariate analysis. More specifically, when ticagrelor prescription at discharge was compared with clopidogrel prescription, a significant death reduction was found in both, the univariate and the multivariate Cox analysis [HR: 4.54 (95% CI 2.26–9.13); p<0.001 and HR: 2.61 (95% CI 1.16–5.90); p=0.021, respectively].

KM curves according NAD and CVD disease

Conclusion

New antiplatelet drugs, especially ticagrelor, showed lower rates of mortality in patients with CVD without differences for bleeding. Despite the recommendations of current clinical guidelines for high risk patients with ACS, the use of NADs is very low in “real-life” patients with previous CVD.

An Antiplatelet Monoclonal Antibody That Inhibits ADP and Epinephrine-Induced Aggregation

A monoclonal antibody (Mab) named EDU-3, was produced by fusing splenocytes from one Balb/c mouse, immunized with a mixture of platelets and non-T cells from heparinized human peripheral blood, with the HAT-sensitive myeloma line P3-NS1/ l.Ag4.1. By indirect immunofluorescence (IF) it was seen that this Mab reacted with all normal human platelets and bone marrow megakaryocytes, but did not react with lymphoid cells from normal donors, or platelets from Glanzmann’s thrombasthenia (GT) patients. Immunoprecipitation and SDS-PAGE experiments demonstrated that this Mab recognizes an epitope on the IIb-IIIa glycoprotein complex (GPC). EDU-3 inhibited platelet aggregation and release of ATP induced by ADP and epinephrine. Aggregation induced by arachidonic acid, ristocetin and bovine factor VIII were not inhibited by EDU-3. The difference between EDU-3 and other Mab directed against the IIb-IIIa GPC is discussed.

Management of Tizanidine Withdrawal Syndrome: A Case Report

Most drugs that act on the central nervous system (CNS) require dose titration to avoid withdrawal syndrome. Tizanidine withdrawal syndrome is caused by adrenergic discharge due to its α₂-agonist mechanism and is characterized by hypertension, reflex tachycardia, hypertonicity, and anxiety. Although tizanidine withdrawal syndrome is mentioned as a potential side effect of cessation, it is not common and there have been few reports. We present the case of a 31-year-old woman with tizanidine withdrawal syndrome after discontinuing medication prescribed for a muscle contracture (tizanidine). She showed high adrenergic activity with nausea, vomiting, generalized tremor, dysthermia, hypertension, and tachycardia. Symptoms were reversed and successful reweaning was achieved by restarting tizanidine followed by slow downward titration. Withdrawal syndrome should be considered when drugs targeting the CNS are suddenly stopped. Weaning regimens should be closely monitored for acute withdrawal reactions.

Modeling Filler Dispersion along a Twin-Screw Extruder

Particle size distribution strongly affects physical and mechanical properties of filled polymers. A new model has been developed to predict agglomerate size distribution in a twin-screw extruder (TSE). The model considers the break-up and erosion processes and it uses agglomerate size population balance in its mathematical formulation. The model parameters were evaluated in simple field flow. This paper shows the validation of the model along the extruder using different screw configurations of a short twin screw extruder. Flow parameters along of the TSE necessaries to apply the new dispersion model have been calculated with ©Ludovic software. Calcium carbonate filled polypropylene system was used as model compound. The agglomerate size distribution was evaluated from micrographs of polished samples at different locations along the extruder obtained by reflected light microscopy in conjunction with-semiautomatic image analysis.

Comparison of the effects of nerve growth factor and superoxide dismutase on vascular extravasation in experimental burns

Superoxide dismutase (SOD), a free-radical scavenger, inhibits the increase of vascular permeability in experimental burn lesions in rats. In this study the aim was to determine whether Nerve Growth Factor (NGF), which has been implicated in the modulation of some inflammatory reactions, behaves in an analogous way. The study compares the haematocrit (Ht) and haemoglobin (Hb) variations in three groups of rats treated respectively with saline solution, SOD and NGF, immediately after causing a 25 per cent dermal burn injury. Statistical comparison (Student's t test) of the Ht and Hb variations between the Control group (Ht and Hb increase) and the NGF group (Ht and Hb decrease), shows significant differences in the intervals between 15 and 60 min (P < 0.01) and between 60 and 120 min (P < 0.05). Although SOD is able to control extravasation in the immediate postburn period (basal-15 min), NGF has a comparable effect in subsequent periods. The overall action of NGF shows that this agent is able to maintain Ht and Hb values at basal levels even after 120 min postburn. These results seem to be the first evidence of an inhibitory effect of NGF on the vascular permeability in burn lesions.

Defective platelet adhesion on vessel subendothelium in uremic patients

Bleeding time, platelet retention on glass beads, and ristocetin-induced platelet agglutination (RIPA) in platelet-rich plasma were simultaneously determined for 20 patients with chronic renal failure and previous hemorrhagic history. In seven patients chosen at random out of a group of 16 in whom the three tests were abnormal, RIPA of uremic-isolated platelets in presence of normal platelet-poor plasma (PPP) and of normal platelets in presence of patient PPP were performed. In all cases, the first assay showed diminished agglutination, suggesting a platelet defect; however, uremic PPP did not inhibit the agglutination of normal platelets. In the same patients, the interaction of platelets with subendothelium was evaluated using Baumgartner's perfusion method. The subendothelial surface covered by platelets was significantly decreased in experiments with uremic whole blood when compared to normal controls. The interaction of platelets with subendothelium was also decreased when perfusions were carried out with platelet-plasma mixtures containing either normal washed platelets and uremic PPP or uremic washed platelets and normal PPP. These results show an impaired platelet adhesion caused both by a platelet and a plasmatic abnormality. Since uremic PPP decreased the adhesion of normal platelets to subendothelium but did not inhibit RIPA, it seems probable that the plasmatic defect could result in a defective binding between vWF and subendothelium. The influence of the red cell count on the platelet adhesion to subendothelium was reconfirmed by comparing perfusions of reconstituted blood with hematocrit values of 20% to 23% and 40% to 45%. In summary, a defective platelet adhesion to subendothelium has been postulated in uremic patients, caused by platelet and plasmatic alterations that are influenced by a low hematocrit.

An antiplatelet monoclonal antibody that inhibits ADP and epinephrine-induced aggregation

A monoclonal antibody (Mab) named EDU-3, was produced by fusing splenocytes from one Balb/c mouse, immunized with a mixture of platelets and non-T cells from heparinized human peripheral blood, with the HAT-sensitive myeloma line P3-NS1/1.Ag4.1. By indirect immunofluorescence (IF) it was seen that this Mab reacted with all normal human platelets and bone marrow megakaryocytes, but did not react with lymphoid cells from normal donors, or platelets from Glanzmann's thrombasthenia (GT) patients. Immunoprecipitation and SDS-PAGE experiments demonstrated that this Mab recognized an epitope on the IIb-IIIa glycoprotein complex (GPC). EDU-3 inhibited platelet aggregation and release of ATP induced by ADP and epinephrine. Aggregation induced by arachidonic acid, ristocetin and bovine factor VIII were not inhibited by EDU-3. The difference between EDU-3 and other Mab directed against the IIb-IIIa GPC is discussed.