Erythromycin inhibition of 50S ribosomal subunit formation in Escherichia coli cells.

The effects of erythromycin on the formation of ribosomal subunits were examined in wild-type Escherichia coli cells and in an RNase E mutant strain. Pulse-chase labelling kinetics revealed a reduced rate of 50S subunit formation in both strains compared with 30S synthesis, which was unaffected by the antibiotic. Growth of cells in the presence of [14C]-erythromycin showed drug binding to 50S particles and to a 50S subunit precursor sedimenting at about 30S in sucrose gradients.

Structure-activity relationships for six ketolide antibiotics.

Six structurally related 3-keto-substituted macrolide antibiotics (ketolides) were compared for concentration-dependent inhibitory effects on growth rate, viable cell number, and protein synthesis rates in Staphylococcus aureus cells. Inhibitory effects on 50S ribosomal subunit formation were also examined, as this is a second target for these antibiotics. A concentration range of 0.

Specific inhibition of 50S ribosomal subunit formation in Staphylococcus aureus cells by 16-membered macrolide, lincosamide, and streptogramin B antibiotics.

The translational functions of the bacterial ribosome are the target for a large number of antimicrobial agents. The 14- and 16-membered macrolides, the lincosamides, and the streptogramin B type antibiotics are thought to share certain inhibitory properties, based on both biochemical and genetic studies. We have shown previously that the 14-membered macrolides, like erythromycin, have an equivalent inhibitory effect on translation and the formation of the 50S ribosomal subunit in growing bacterial cells.

Evernimicin (SCH27899) inhibits both translation and 50S ribosomal subunit formation in Staphylococcus aureus cells.

The effects of the everninomicin antibiotic evernimicin (SCH27899) on growing Staphylococcus aureus cells were investigated. Cellular growth rates and viable cell numbers decreased with increasing antibiotic concentrations. The rate of protein synthesis, measured as (35)S-amino acid incorporation, declined in parallel with the growth rate.

Macrolide and ketolide antibiotic separation by reversed phase high performance liquid chromatography.

Twenty different macrolide and ketolide antibiotics were analyzed by reversed phase high performance liquid chromatography on an ODS-2 cartridge column. Each of these compounds was uniquely separated and purified by varying the flow rate. Retention times of the individual drugs were proportional to the flow rate of the mobile phase.

Molecular investigation of the postantibiotic effects of clarithromycin and erythromycin on Staphylococcus aureus cells.

The kinetics of recovery after inhibition of growth by erythromycin and clarithromycin were examined in Staphylococcus aureus cells. After inhibition for one mass doubling by 0.5 microg of the antibiotics/ml, a postantibiotic effect (PAE) of 3 and 4 h duration was observed for the two drugs before growth resumed.

Superiority of 11,12 carbonate macrolide antibiotics as inhibitors of translation and 50S ribosomal subunit formation in Staphylococcus aureus cells.

Three pairs of related macrolide antibiotics, differing at the 11,12 position of the macrolactone ring, were compared for effects on growth rate, cell viability, protein synthesis, and 50S ribosomal subunit formation in Staphylococcus aureus cells. For each parameter measured, the 11,12 carbonate-derivatized compound was more inhibitory compared with the corresponding 11,12-hydroxy antibiotic. Substitution at the 3-position of the ring was also important in the relative inhibition observed.

Macrolide antibiotic inhibition of translation and 50S ribosomal subunit assembly in methicillin-resistant Staphylococcus aureus cells.

Methicillin-resistant Staphylococcus aureus cells were treated with three macrolide antibiotics to examine the inhibitory effect of the drugs on the growth rate and cell viability. Inhibition of protein synthesis and 50S ribosomal subunit assembly were also examined. The growth rate and cell viability were reduced by each antibiotic in both erythromycin-susceptible and erythromycin-resistant MRSA organisms.

Evidence for a unique elastic sheath surrounding the vesicular arteries of the rabbit urinary bladder--studies of the microvasculature with microscopy and vascular corrosion casting.

Because the urinary bladder stores and releases urine, its normal function includes filling and emptying, accompanied by distension and relaxation. It is known that chronic distension compromises blood flow. Recent studies of the rabbit bladder vasculature have described specializations of that vasculature that appear to enhance blood flow in the bladder wall during distension.

Inhibition of translation and 50S ribosomal subunit formation in Staphylococcus aureus cells by 11 different ketolide antibiotics.

Eleven structurally similar ketolide antibiotics were tested at a concentration of 1 microg/ml for their relative inhibitory effects on growth and ribosome activities in Staphylococcus aureus cells. Ten of the compounds examined had an inhibitory effect on protein synthesis at this concentration and eight of the 11 compounds were also effective inhibitors of the formation of the 50S ribosomal subunit. All of the drugs tested inhibited protein synthesis to a greater extent than they affected 50S subunit formation.

A comparison of the inhibition of translation and 50S ribosomal subunit formation in Staphylococcus aureus cells by nine different macrolide antibiotics.

Nine structurally similar macrolide antibiotics were tested at a concentration of 0.5 microg/ml for their relative inhibitory effects on ribosome functions in Staphylococcus aureus cells. Eight of the compounds examined inhibited protein synthesis at this concentration.

Human mast cell tryptase fibrinogenolysis: kinetics, anticoagulation mechanism, and cell adhesion disruption.

Tryptase is a 31 kDa, glycosylated, trypsin-like enzyme stored in and released from mast cell granules. Human tryptase exists as a tetramer, binds heparin, and has a limited substrate specificity, yet it displays remarkable resistance to inhibition by blood plasma proteinase inhibitors. In this study we have examined the cleavage of human fibrinogen by tryptase.

Azithromycin and clarithromycin inhibition of 50S ribosomal subunit formation in Staphylococcus aureus cells.

The ID50 values for azithromycin and clarithromycin inhibition of translation and of 50S assembly in Staphylococcus aureus cells have been measured. For clarithromycin, 50% inhibition of growth occurred at 0.075 microg/ml, and the effects on translation and 50S formation were equivalent at 0.

Inactivation of human lung tryptase: evidence for a re-activatable tetrameric intermediate and active monomers.

Human lung tryptase (HLT), a trypsin-like serine proteinase stored as an active enzyme in association with heparin in mast cell granules, is released into the extracellular environment when mast cells are activated. Tryptases are unusual in that they form tetramers and bind heparin. As there are no known endogenous tryptase inhibitors, loss of heparin and dissociation of the active tetrameric enzyme to inactive monomers has been proposed as the mechanism of control.

50S ribosomal subunit synthesis and translation are equivalent targets for erythromycin inhibition in Staphylococcus aureus.

Macrolide antibiotics like erythromycin can prevent the formation of the 50S ribosomal subunit in growing bacterial cells, in addition to their inhibitory effect on translation. The significance of this novel finding has been further investigated. The 50% inhibitory doses of erythromycin for the inhibition of translation and 50S subunit assembly in Staphylococcus aureus cells were measured and were found to be identical.

Macrolide antibiotics inhibit 50S ribosomal subunit assembly in Bacillus subtilis and Staphylococcus aureus.

Macrolide antibiotics are clinically important antibiotics which are effective inhibitors of protein biosynthesis in bacterial cells. We have recently shown that some of these compounds also inhibit 50S ribosomal subunit formation in Escherichia coli. Now we show that certain macrolides have the same effect in two gram-positive organisms, Bacillus subtilis and Staphylococcus aureus.

Erythromycin inhibits the assembly of the large ribosomal subunit in growing Escherichia coli cells.

Erythromycin and other macrolide antibiotics have been examined for their effects on ribosome assembly in growing Escherichia coli cells. Formation of the 50S ribosomal subunit was specifically inhibited by erythromycin and azithromycin. Other related compounds tested, including oleandomycin, clarithromycin, spiramycin, and virginiamycin M1, did not influence assembly.

Human mast cell tryptase isoforms: separation and examination of substrate-specificity differences.

Tryptases are trypsin-like enzymes found in mast cell granules that appear to exist as tetramers. These enzymes are not controlled by blood plasma proteinase inhibitors and only cleave a few physiological substrates in vitro, including high-molecular-mass kininogen (HMMK) and vasoactive intestinal peptide (VIP). Purified human lung mast cell tryptase (HLT) contained two bands of approx.

The effect of prefixation on the quality of vascular corrosion casts of rat heart.

To help define the optimal conditions for the preparation of vascular corrosion casts of rat heart, we examined the effect of prefixation with aldehyde fixatives on the perfusion rates of rat heart and on the quality of vascular casts. For these studies, beating hearts were removed from rats, cannulated via the aortic stump, arrested with KCl, perfused retrograde with buffered saline or fixative, and infused with resin to prepare corrosion casts. Fixatives used were 2.

Ozone, but not nitrogen dioxide, fragments elastin and increases its susceptibility to proteolysis.

The effects of ozone (O3) and nitrogen dioxide (NO2) on the solubility and proteolytic susceptibility of elastin were examined to better understand how these oxidant air pollutants might damage the lung. In vitro O3 exposures at pH 7.4 resulted in the complete solubilization of elastin, but NO2 had no effect on solubility.

Case report: the anticardiolipin (antibody) syndrome.

The anticardiolipin antibody syndrome is relatively uncommon. It should be suspected mostly in young people with unexplained embolic or thrombotic events. A young patient with an abnormal prothrombin time, partial thromboplastin time, or venereal disease research lab test with one of the above noted vascular events would be a suspect for this disorder.

Absence of denervation supersensitivity to neurokinin A in the rat vas deferens.

1. Unilateral denervation of the rat vas deferens (RVD) was performed under anesthesia. The animals were allowed to recover 4 or 10 days and then concentration-effect (C-E) curves to noradrenaline (NA) and neurokinin A (NKA) were constructed in denervated and control RVD.

Non-T-cell lymphoblastic lymphoma with extensive osteolytic lesions and hypercalcemia.

The syndrome of osteolytic lesions and hypercalcemia is commonly associated with well-differentiated B-cell neoplasms, such as multiple myeloma. The association of this syndrome with high-grade non-Hodgkin's lymphoma is rare. We have described a 20-year-old man with a non-T-cell lymphoblastic lymphoma manifested by extensive osteolytic lesions and hypercalcemia (serum calcium value of 13.