Comparative pharmacology of human beta-adrenergic receptor subtypes--characterization of stably transfected receptors in CHO cells.

Although many beta1-receptor antagonists and beta2-receptor agonists have been used in pharmacotherapy for many years their pharmacological properties at all three known subtypes of beta-adrenergic receptors are not always well characterized. The aim of this study was, therefore, to provide comparative binding characteristics of agonists (epinephrine, norepinephrine, isoproterenol, fenoterol, salbutamol, salmeterol, terbutalin, formoterol, broxaterol) and antagonists (propranolol, alprenolol, atenolol, metoprolol, bisoprolol, carvedilol, pindolol, BRL 37344, CGP 20712, SR 59230A, CGP 12177, ICI 118551) at all three subtypes of human beta-adrenergic receptors in an identical cellular background. We generated Chinese hamster ovary (CHO) cells stably expressing the three beta-adrenergic receptor subtypes at comparable levels. We characterized these receptor subtypes and analyzed the affinity of routinely used drugs as well as experimental compounds in competition binding studies, using the non-selective antagonist 125I-cyanopindolol as a radioligand. Furthermore, we analyzed the beta-receptor-mediated adenylyl cyclase activity in isolated membranes from these cell lines. The results from our experiments show that all compounds exhibit distinct patterns of selectivity and activity at the three beta-receptor subtypes. In particular, a number of beta2- or beta3-receptor agonists that are inverse agonists at the other subtypes were identified. In addition, beta1-receptor antagonists with agonistic activity at beta2- and beta3-receptors were found. These specific mixtures of agonism, antagonism, and inverse agonism at different subtypes may have important implications for the therapeutic use of the respective compounds.

Validation of immunolocalization of the urokinase receptor expression in ductal carcinoma in situ of the breast: comparison with detection by non-isotopic in-situ hybridization.

AIMS: Ductal carcinoma in situ (DCIS) is a pre-invasive form of mammary carcinoma with no microscopic evidence of cancer cell invasion through the basement membrane. However, for initiation of invasion, tumour cells have to acquire and focus proteolytic activity on to the cell surface in order to infiltrate the surrounding extracellular matrix. The receptor (uPA-R or CD87) for the serine protease urokinase-type plasminogen activator (uPA) plays a central role in invasion and metastasis. This study was performed to determine and localize m-RNA and protein of uPA-R in ductal carcinoma in situ of the breast. METHODS AND RESULTS: We analysed uPA-R mRNA and protein expression by in-situ hybridization and immunohistochemistry, respectively, in 50 formalin-fixed, paraffin-embedded specimens of DCIS. Three different antibodies were used to stain cell-associated uPA-R; chicken polyclonal antibody (pAb) HU277 and monoclonal antibodies (mAb) IID7 and 3936. In all cases, myoepithelial and stromal cells reacted with either antibody. Especially, reaction of macrophage-like cells with mAb 3936 resulted in a well-marked and bright staining. Applying mAb IID7, in 46 of the 50 breast specimens tumour cells showed a positive immunoreaction. Likewise pAb HU277 stained tumour cells in 40 of the 50 cases, whereas mAb 3936 reacted with only 24 of the 50 tissue sections. Endothelial cells were marked by both mAb IID7 and pAb HU277 (46/50 and 35/50, respectively); mAb 3936 did not label at all. All of the cell types stained by mAb IID7 and pAb HU277 also displayed reactivity with uPA-R mRNA-specific antisense oligonucleotides in in-situ hybridization. CONCLUSIONS: Our results reveal the presence of the tumour invasion-related receptor for the protease uPA not only in invasive ductal breast carcinoma but also in different types of DCIS.

Aztreonam concentrations in human tissues obtained during thoracic and gynecologic surgery.

The concentrations of aztreonam in human tissues obtained during surgery were measured after a single 2-g intravenous dose. The average concentration in the skeletal muscle, atrial appendage, lung, sternum, pericardial fluid, endometrium, myometrium, fallopian tube, and ovary varied from 3 to 33 micrograms/g (or microgram/ml). These concentrations significantly exceed the MIC for 90% of strains for most members of the family Enterobacteriaceae.

Metabolism and pharmacokinetics of aztreonam in healthy subjects.

The metabolism and pharmacokinetics of aztreonam (SQ 26,776) were studied in four healthy male volunteers, each of whom received single 500-mg intravenous and intramuscular doses of 14C-labeled drug according to a two-way crossover design. Serial samples of serum, urine, and feces were assayed for aztreonam and metabolites. Serum pharmacokinetics of aztreonam administered intravenously were described by an open, linear, two-compartment kinetic model. Kinetics of intramuscular aztreonam followed a one-compartment model with first-order absorption and elimination. Intramuscular bioavailability was 100%. After either intravenous or intramuscular administration, aztreonam was eliminated primarily by urinary excretion of unchanged drug (about 66% of dose), whereas only 1% of the dose was found as unchanged drug in the feces, presumably owing to biliary secretion. The average elimination half-life of aztreonam was 1.6 and 1.7 h, respectively, for intravenous and intramuscular administration. Aztreonam did not undergo extensive metabolism; the most prominent biotransformation product of aztreonam was SQ 26,992, the compound resulting from the hydrolytic opening of the beta-lactam ring. Urinary and fecal SQ 26,992 constituted 7 and 3% of the administered dose, respectively. SQ 26,992 was eliminated at a considerably slower rate than was aztreonam.

Human serum protein binding of cephalosporin antibiotics in vitro.

The published values for serum protein binding of antibiotics vary considerably depending upon the method and experimental conditions used. A rapid, simple, and standardized ultrafiltration procedure for determination of the serum protein binding of antibiotics has been developed and used to compare the binding characteristics of four marketed cephalosporins. The human serum protein binding of cephradine, cephalexin, cephalothin, and cefazolin at 37 degrees C. and physiological pH (7.4) was found to be 13.8, 12.4, 71.2, and 89.2 per cent, respectively. These values fall within the range of published values for these antibiotics.