Platelet glycoprotein IIb/IIIa inhibition using eptifibatide with primary coronary stenting for acute myocardial infarction: a 30-day follow-up study.

The results of primary coronary stenting for acute myocardial infarction (AMI) have been reported to improve significantly with the concomitant administration of platelet glycoprotein IIb/IIIa inhibitor abciximab. There are, however, no data available with the use of eptifibatide, a more cost-effective, small-molecule GP IIb/IIIa blocker with a shorter half-life. In a prospective multicenter feasibility and efficacy study, we assigned 55 consecutive patients with AMI being taken up for primary stenting to receive eptifibatide just before the procedure (two boluses of 180 microg/kg 10 min apart and a 24-hr infusion of 2 microg/kg/min). Clinical outcomes were evaluated at 30 days after the procedure. The angiographic patency of the vessel with TIMI flow rates, TIMI myocardial perfusion (TMP) grade, and corrected TIMI frame counts were assessed at the end of procedure and before hospital discharge. At 30 days, the primary endpoint, a composite of death, myocardial infarction, and urgent target vessel revascularization (TVR) was seen in 12.7% of patients. The TIMI 3 and TMP grade 3 flow, which was seen in 93% and 86% of patient, respectively, at the end of the procedure, declined to 86% and 78%, respectively (P < 0.05) before hospital discharge. Corrected TIMI frame counts also decreased from 25.7 +/- 7.2 to 22.9 +/- 6.8 (P < 0.05). There were five (9.1%) instances of subacute thrombosis (SAT) presenting as AMI, needing urgent TVR in all, within 3-5 days of the primary procedure. No excessive bleeding complication, directly attributable to the use of eptifibatide, was observed. The study was terminated prematurely because of an unacceptable SAT rate. Administration of eptifibatide along with primary stenting for AMI is associated with a high TIMI 3 and TMP grade 3 flow acutely. However, these flows decline significantly before hospital discharge and lead to a high rate of SAT. The dosage and duration of infusion of eptifibatide in this setting needs further evaluation.     

Measurement of Free Versus Total Therapeutic Monoclonal Antibody in Pharmacokinetic Assessment is Modulated by Affinity,Incubation Time,and Bioanalytical Platform

Decisions about efficacy and safety of therapeutic proteins (TP) designed to target soluble ligands are made in part by their ex vivo quantification. Ligand binding assays (LBAs) are critical tools in measuring serum TP levels in pharmacokinetic, toxicokinetic, and pharmacodynamic studies. This study evaluated the impact of reagent antibody affinities, assay incubation times, and analytical platform on free or total TP quantitation. An ELISA-based LBA that measures monoclonal anti-sclerostin antibody (TPx) was used as the model system. To determine whether the method measures free or total TPx, the effects of K_on, K_off, and K_D were determined. An 8:1 molar ratio of sclerostin (Scl) to TPx compared to a 1:1 molar ratio produced by rabbit polyclonal antibodies to TPx was required to achieve IC₅₀, a measure of TPx interference effectiveness, making it unclear whether the ELISA truly measured free TPx. Kinetic analysis revealed that Scl had a rapid dissociation rate (K_off) from TPx and that capture and detection antibodies had significantly higher binding affinities (K_D) to TPx. These kinetic limitations along with long ELISA incubation times lead to the higher molar ratios (8:1) required for achieving 50% inhibition of TPx. However, a microfluidic platform with the same reagent pairs required shorter incubations to achieve a lower Scl IC₅₀ molar ratio (1:1). The findings from this study provide the bioanalytical community with a deeper understanding of how reagent and platform selection for LBAs can affect what a particular method measures, either free or total TP concentrations.KEY WORDS: affinity and kinetics, association and dissociation, free versus total, interference, ligand binding assay     

Influence of relative hypoparathyroidism on the responsiveness to recombinant human erythropoietin in hemodialysis patients

BACKGROUND/AIM: It has been shown in a few studies examining small patient groups that high levels of intact parathyroid hormone (iPTH) were associated with a less efficient response to recombinant human erythropoietin (rHuEPO). However, the responsiveness to rHuEPO in hemodialysis (HD) patients with relative hypoparathyroidism remains undetermined. This study examines the responsiveness to rHuEPO in HD patients with relative hypoparathyroidism. METHODS: We retrospectively studied 19 nondiabetic patients (mean age 44.3 +/- 8.2 years, age range 29.4-55.6 years) treated with HD for chronic glomerulonephritis. Of the 19 patients, 8 (group A) had iPTH levels <100 pg/ml for the preceding 6 months without administration of 1,25-(OH)(2)-vitamin D(3). Eleven patients had iPTH levels >100 pg/ml (group B). Hematocrit (Hct) and rHuEPO doses were recorded for statistical analysis. RESULTS: In patients of groups A and B, the rHuEPO dose (U/kg/week) was 55.21 +/- 16.23 vs. 84.08 +/- 24.56 (p = 0.01); Hct (%) 33.29 +/- 1.72 vs. 31.43 +/- 2.98 (p = 0.67), and rHuEPO resistance index (weekly rHuEPO dose/Hct) 81.38 +/- 16.64 vs. 155.63 +/- 42.22 (p < 0.001). Furthermore, weekly rHuEPO dose and rHuEPO resistance index correlated positively with serum iPTH levels (R = 0.765, p < 0.001; R = 0.764, p < 0.001), whereas the Hct correlated negatively with serum iPTH levels (R = -0.400, p = 0.045). The alkaline phosphatase level (IU/l) was lower (50.46 +/- 12.87 vs. 69.61 +/- 20.68, p = 0.17) in group A. CONCLUSION: Our observations suggest that the lower the iPTH levels of chronic HD patients, even with relative hypoparathyroidism, the better the responsiveness to rHuEPO.     

Studies on the release of interleukin-1 (IL-1), tumor necrosis factor (TNF) and lysozyme from human non-adherent mononuclear cells (nMNC) in vitro after treatment with cisplatin and other biological response modifiers.

The supernatants collected from cisplatin, lipopolysaccharide (LPS), muramyl dipeptide (MDP) or recombinant interferon gamma (rIFN-gamma) treated non-adherent mononuclear cells (with NK cell activity) enhanced thymocyte proliferation by a submitogenic concentration of concanavalin A as compared to untreated nMNC. Supernatants collected from cisplatin or rIFN-gamma treated nMNC also demonstrated enhanced cytotoxicity against actinomycin-D treated L929 cells, suggesting that cisplatin or rIFN-gamma treated nMNC release tumor necrosis factor (TNF) into the culture supernatant. On the other hand, supernatant collected from untreated nMNC showed little TNF activity. Treatment of nMNC with cisplatin, LPS, MDP or rIFN-gamma resulted in enhanced release of lysozyme into the culture medium as compared to untreated nMNC.     

A case of hypersensitivity to soluble and isophane insulins but not to insulin glargine

Insulin is an important agent for the treatment of diabetes mellitus (DM). Allergic reactions to insulin therapy, although rare, have been evident since animal insulin became available for the treatment of DM in 1922. Hypersensitivity to insulin has considerably been reduced with the introduction of human insulin produced by recombinant deoxyribonucleic acid technology. Here, we present a case of Type 2 DM who demonstrated immediate (Type 1) hypersensitivity reaction on the sites of subcutaneous injection of soluble and isophane insulin but insulin glargine was tolerated well and provided good glycemic control.KEY WORDS: Allergic reaction, diabetes mellitus, hypersensitivity, insulin     

Angiotensin II receptor blocker irbesartan attenuates sleep apnea–induced cardiac apoptosis and enhances cardiac survival and Sirtuin 1 upregulation

Background

The purpose of this study was to investigate whether or not angiotensin II type 1 receptor blocker irbesartan (ARB) with a partial agonist of PPAR-γ could protect against chronic nocturnal intermittent hypoxia (CIH)–induced cardiac Fas/FasL-mediated to mitochondria-mediated apoptosis.

Methods

Sprague–Dawley rats were in a normoxic control group (CON-G), or rats were in a chronic nocturnal intermittent hypoxia group (HP-G, from 3 to 7% oxygen versus 21% oxygen per forty seconds cycle, nocturnally 8 h per day for 1 month), or rats were in a chronic nocturnal intermittent hypoxia group pretreated with ARB (50 mg/kg/day, S.C.) (ARB-HP-G). Echocardiography, H&E staining, TUNEL staining, and Western blotting were measured in the left ventricle.

Results

Hypoxia-induced SIRT1 degradation, Fas receptors, FADD, active caspase-8 and caspase-3 (Fas/FasL apoptotic pathway) and Bax, tBid, active caspase-9 and -3 (mitochondrial apoptotic pathway) and TUNEL-positive apoptosis were reduced in ARB-HP-G when compared with HP-G. IGF-I, IGF1 receptor, p-PI3k, p-Akt, Bcl2, and Bcl-XL (IGF1/PI3K/AKT pro-survival pathway) were increased in ARB-HP-G compared to HP-G.

Conclusions

Our findings suggest that the ARB may prevent cardiac Fas/FasL to mitochondrial apoptotic pathways and enhance cardiac IGF1/PI3K/AKT pro-survival pathway in the sleep apnea model associated with JNK de-activation and SIRT1 upregulation. ARB prevents chronic sleep apnea–enhanced cardiac apoptosis via enhancing survival pathways.

     

Pathophysiology,Diagnosis, and Management of Coronary No-Reflow Phenomenon

Coronary no-reflow phenomenon is a lethal mechanism of ongoing myocardial injury, following successful revascularization of an infarct-related coronary artery. Incidence of this phenomenon is high following percutaneous intervention, and is associated with adverse in-hospital and long-term outcomes. Several mechanisms such as ischemia-reperfusion injury and distal microthromboembolism in genetically susceptible patients and those with preexisting endothelial dysfunction have been implicated. However, the exact mechanism in humans is still poorly understood. Several investigative and treatment strategies within and outside the cardiac catheterization laboratory have been proposed, but have not uniformly shown success in reducing mortality or in preventing adverse left ventricular remodeling resulting from this condition. The aim of this article is to provide a brief and concise review of the current understanding of the pathophysiology, clinical predictors, and investigations and management of coronary no-reflow phenomenon.