Therapeutic effect of atorvastatin on kidney functions and urinary excretion of Glimepiride in healthy adult human male subjects

Glimepiride and atorvastatin in combination are commonly employed for treating the hyperglycemia and dyslipidemia, respectively, in patients of type 2 diabetes. The present study was designed to find out the influence of atorvastatin on urinary excretion and renal clearance of Glimepiride in healthy adult male volunteers. In each experimental subject, Glimepiride 2mg was given orally after an overnight fasting. Samples of blood and urine were taken at different specific time intervals. After a washout period of ten days, Glimepiride 2mg was co-administered with atorvastatin 20mg orally. Post-medication, blood and urine samples were collected following the same sampling schedule as for Glimepiride alone. The samples were analyzed for Glimepiride and creatinine concentration by HPLC-UV and Spectrophotometer, respectively. Mean (±SE) values for blood pH 7.445±0.05 and 7.382±0.05, urine pH 4.972±0.08 and 5.08±0.10, diuresis 0.0207±0.00 and 0.0237±0.00ml/min/kg, endogenous creatinine in plasma 9.048±0.33 and 8.613±0.024µg/ml, endogenous creatinine in urine 512.34±18.20 and 556.72±4.60µg/ml, Glimepiride plasma concentration 0.16069±0.00 and 0.3227±0.01µg/ml, Glimepiride urine concentration 1.5994±0.03 and 0.8665±0.04µg/ml, renal clearance of creatinine 1.224±0.09 and 1.550±0.09ml/min/kg, renal clearance of Glimepiride 0.2064±0.01 and 0.0641±0.00ml/min/kg and clearance ratio 0.1791±0.01 and 0.0414±0.00 were observed for Glimepiride alone and its concurrent administration with atorvastatin, respectively. Atorvastatin decreased the urinary excretion and renal clearance of Glimepiride due to which chances of hypoglycemia provokes and renal handling of Glimepiride involves back diffusion besides glomerular filtration and no influence of atorvastatin was seen on these mechanisms.

IGIF does not drive Th1 development but synergizes with IL-12 for interferon-gamma production and activates IRAK and NFkappaB

In these studies, IFN gamma-inducing factor (IGIF), unlike IL-12, did not drive Th1 development in BALB/c or C57BL/6 mice, but like IL-1alpha, potentiated IL-12-driven Th1 development in BALB/c mice. IGIF and IL-12 synergized for IFN gamma production from Th1 cells. Unlike IL-1alpha, IGIF had no effect on Th2 cells. IGIF signaled through IRAK, IL-1 receptor-associated kinase, to induce nuclear translocation of p65/p50 NFkappaB in Th1 cells. IL-1alpha had no effect on proliferation, cytokine production, or NFkappaB activation in Th1 cells but activated NFkappaB and proliferation in Th2 cells. Thus, Th1 and Th2 cells may differ in responsiveness and receptor expression for IL-1 family molecules. IGIF and IL-1alpha may differentially amplify Th1 and Th2 effector responses, respectively.

Kinetic analysis of ligand binding to interleukin-2 receptor complexes created on an optical biosensor surface

The interleukin-2 receptor (IL-2R) is composed of at least three cell surface subunits, IL-2R alpha, IL-2R beta, and IL-2R gamma c. On activated T-cells, the alpha- and beta-subunits exist as a preformed heterodimer that simultaneously captures the IL-2 ligand as the initial event in formation of the signaling complex. We used BIAcore to compare the binding of IL-2 to biosensor surfaces containing either the alpha-subunit, the beta-subunit, or both subunits together. The receptor ectodomains were immobilized in an oriented fashion on the dextran matrix through unique solvent-exposed thiols. Equilibrium analysis of the binding data established IL-2 dissociation constants for the individual alpha- and beta-subunits of 37 and 480 nM, respectively. Surfaces with both subunits immobilized, however, contained a receptor site of much higher affinity, suggesting the ligand was bound in a ternary complex with the alpha- and beta-subunits, similar to that reported for the pseudo-high-affinity receptor on cells. Because the binding responses had the additional complexity of being mass transport limited, obtaining accurate estimates for the kinetic rate constants required global fitting of the data sets from multiple surface densities of the receptors. A detailed kinetic analysis indicated that the higher-affinity binding sites detected on surfaces containing both alpha- and beta-subunits resulted from capture of IL-2 by a preformed complex of these subunits. Therefore, the biosensor analysis closely mimicked the recognition properties reported for these subunits on the cell surface, providing a convenient and powerful tool to assess the structure-function relationships of this and other multiple subunit receptor systems.

Soluble IL-2 receptor beta and gamma subunits: ligand binding and cooperativity

Biologically relevant interleukin-2 receptors (IL-2Rs) are present in two affinity states on responsive cells. High affinity receptors (HAR) apparently exist as heterotrimers (alpha, beta and gamma) while the other functional complex, the intermediate affinity receptor (IAR), is comprised of beta and gamma chains. The mechanisms by which the beta and gamma subunits contribute the formation of HAR and IAR are still unclear. Soluble forms of the beta and gamma chains were cloned, epitope-tagged, expressed in insect cells and purified. IL-2 binding and neutralization of IL-2 bioactivity by beta and gamma extracellular domains (ectodomains) was analyzed by several biochemical and biological approaches. The results indicate that beta clearly binds IL-2 with low affinity (KI-KD = 3 microM) whereas gamma binding is detectable, but of very low affinity (apparent KI > 15 microM) in the absence of beta. Interestingly, combinations of beta and gamma ectodomains interact to bind IL-2 with higher affinity and greater stability than either chain alone. An apparent stable binding complex is formed when beta, gamma, and IL-2 are combined. Ligand binding by the beta and gamma chains in solution is specific for IL-2 and is of sufficient affinity and stability to effectively neutralize IL-2 in biological assays (binding IC50 = biological IC50). Direct analyses of binding kinetics by surface plasmon resonance reveals that the increased affinity and biological neutralizing ability of beta gamma, as compared to beta, is due to a very slow dissociation rate contributed by the gamma ectodomain. While IL-2R beta and gamma cytoplasmic and transmembrane domains are not essential for interactive binding of IL-2, they may contribute to IL2 binding affinity. The recognition and association of IL-2 by the beta gamma IAR appears to be contributed primarily by the beta chain while the stability and dissociation is likely dominated by the gamma chain. It is anticipated that the gamma subunit functions in a similar manner when participating in high affinity IL-4 and IL-7 binding.