This review addresses the 100-year-old Hill equation (published in January 22, 1910), the first formula relating the result of a reversible association (e.g., concentration of a complex, magnitude of an effect) to the variable concentration of one of the associating substances (the other being present in a constant and relatively low concentration). In addition, the Hill equation was the first (and is the simplest) quantitative receptor model in pharmacology. Although the Hill equation is an empirical receptor model (its parameters have only physico-chemical meaning for a simple ligand binding reaction), it requires only minor a priori knowledge about the mechanism of action for the investigated agonist to reliably fit concentration-response curve data and to yield useful results (in contrast to most of the advanced receptor models). Thus, the Hill equation has remained an important tool for physiological and pharmacological investigations including drug discovery, moreover it serves as a theoretical basis for the development of new pharmacological models.

Vitamin D, besides having well‐known control functions of calcium and phosphorus metabolism, bone formation and mineralization, also has a role in the maintenance of immune‐homeostasis. The immune‐regulatory role of vitamin D affects both the innate and adaptive immune system contributing to the immune‐tolerance of self‐structures. Impaired vitamin D supply/regulation, amongst other factors, leads to the development of autoimmune processes in animal models of various autoimmune diseases. The administration of vitamin D in these animals leads to improvement of immune‐mediated symptoms. Moreover, in human autoimmune diseases, such as multiple sclerosis, or rheumatoid arthritis the pathogenic role of vitamin D has been described. The review aims at describing the complex immune‐regulatory role of vitamin D from the cellular level through autoimmune animal models and depicting the known contribution of vitamin D in the pathogenesis of human autoimmune diseases.

The in vitro activity of caspofungin and micafungin was determined with and without farnesol in RPMI-1640 against Candida parapsilosis biofilms. Drug interactions were examined using the XTT colorimetric assay-based broth microdilution checkerboard method. Drug-drug interactions were assessed utilizing a fractional inhibitory concentration index (

Protective mechanisms of resveratrol against ischemia-reperfusion-induced damage in hearts obtained from Zucker obese rats: the role of GLUT-4 and endothelin. Am J Physiol Heart Circ Physiol 294: H859-H866, 2008. First published December 7, 2007 doi:10.1152/ajpheart.01048.2007.-The resveratrol-induced cardiac protection was studied in Zucker obese rats. Rats were divided into five groups: group 1, lean control; group 2, obese control (OC); group 3, obese rats treated orally with 5 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 of resveratrol (OR) for 2 wk; group 4, obese rats received 10% glucose solution ad libitum for 3 wk (OG); and group 5, obese rats received 10% glucose for 3 wk and resveratrol (OGR) during the 2nd and 3rd wk. Body weight, serum glucose, and insulin were measured, and then hearts were isolated and subjected to 30 min of ischemia followed by 120 min of reperfusion. Heart rate, coronary flow, aortic flow, developed pressure, the incidence of reperfusioninduced ventricular fibrillation, and infarct size were measured. Resveratrol reduced body weight and serum glucose in the OR compared with the OC values (414 Ϯ 10 g and 7.08 Ϯ 0.41 mmol/l, respectively, to 378 Ϯ 12 g and 6.11 Ϯ 0.44 mmol/l), but insulin levels were unchanged. The same results were obtained for the OG vs. OGR group. Resveratrol improved postischemic cardiac function in the presence or absence of glucose intake compared with the resveratrolfree group. The incidence of ventricular fibrillation and infarct size was reduced by 83 and 20% in the OR group, and 67 and 16% in the OGR group, compared with the OC and OG groups, respectively. Resveratrol increased GLUT-4 expression and reduced endothelin expression and cardiac apoptosis in ischemic-reperfused hearts in the presence or absence of glucose intake. Thus the protective effect of resveratrol could be related to its direct effects on the heart. heart; ischemia-reperfusion; diabetes; rat IN THE PAST THREE DECADES, an explosive increase in the number of people diagnosed with diabetes was seen worldwide (7, 48).

Although the A1 adenosine receptor (A1 receptor), the main adenosine receptor type in cardiac muscle, is involved in powerful cardioprotective processes such as ischemic preconditioning, the atrial A1 receptor reserve has not yet been quantified for the direct negative inotropic effect of adenosine. In the present study, adenosine concentration-effect (E/c) curves were constructed before and after pretreatment with FSCPX (8-cyclopentyl-N3-[3-(4-(fluorosulfonyl)benzoyloxy)propyl]-N1-propylxanthine), an irreversible A1 receptor antagonist, in isolated guinea pig atria. To prevent the intracellular elimination of the administered adenosine, NBTI (S-(2-hydroxy-5-nitrobenzyl)-6-thioinosine), a nucleoside transport inhibitor, was used. As expected, NBTI alone and FSCPX-pretreatment alone shifted the adenosine E/c curve to the left and right, respectively. However, in the presence of NBTI, FSCPX-pretreatment appeared to increase the maximal response to adenosine. By means of the receptorial responsiveness method (RRM), our recently developed procedure, adenosine E/c curves generated in the presence of NBTI were corrected for the bias caused by the endogenous adenosine accumulated by NBTI. The corrected curves indicate a substantial A1 receptor reserve for the direct negative inotropy evoked by adenosine. In addition, our results suggest that accumulation of an endogenous agonist may bias the E/c curve constructed with the same or similar agonist that can lead to seemingly paradoxical results.