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Aminoglycoside antibiotics are pseudosaccharides decorated with ammonium groups that are critical for their potent broad-spectrum antibacterial activity. Despite over three decades of speculation whether or not modulation of pKa is a viable strategy to curtail aminoglycoside kidney toxicity, there is a lack of methods to systematically probe amine-RNA interactions and resultant cytotoxicity trends. This study reports the first series of potent aminoglycoside antibiotics harboring fluorinated N1-hydroxyaminobutyryl acyl (HABA) appendages for which fluorine-RNA contacts are revealed through an X-ray cocrystal structure within the RNA A-site. Cytotoxicity in kidney-derived cells was significantly reduced for the derivative featuring our novel β,β-difluoro-HABA group, which masks one net charge by lowering the pKa without compromising antibacterial potency. This novel side-chain assists in evasion of aminoglycoside-modifying enzymes, and it can be easily transferred to impart these properties onto any number of novel analogs.

Biosynthetically inspired manipulation of the antibiotic paromomycin led, in six high-yielding steps, to a ring A harboring an α,β-unsaturated 6'-aldehyde and an allylic 3'-methylcarbonate group. Tsuji deoxygenation in the presence of 5 mol % Pd(2)(dba)(3) and Bu(3)P granted access to a novel series of 3',4'-dideoxy-4',5'-dehydro ring A hybrids. The neomycin-sisomicin hybrid exhibited superior in vitro antibacterial activity to the parent compound neomycin.

Deoxygenation of the diol groups in rings A and D of neomycin in combination with the introduction of an N1-(l)-HABA group in the 2-deoxystreptamine subunit (ring B) leads to a novel and potent antibiotic (1) with activity against strains of S. aureus carrying known aminoglycoside resistance determinants, as well as against an extended panel of Methicillin-resistant S. aureus isolates (n = 50). Antibiotic 1 displayed >64 fold improvement in MIC50 and MIC90 against this MRSA collection when compared to the clinically relevant aminoglycosides amikacin and gentamicin. The synthesis was achieved in six steps and 15% overall yield.

ACHN-490 is a neoglycoside, or "next-generation" aminoglycoside (AG), that has been identified as a potentially useful agent to combat drug-resistant bacteria emerging in hospitals and health care facilities around the world. A focused medicinal chemistry campaign produced a collection of over 400 sisomicin analogs from which ACHN-490 was selected. We tested ACHN-490 against two panels of Gram-negative and Gram-positive pathogens, many of which harbored AG resistance mechanisms. Unlike legacy AGs, ACHN-490 was active against strains expressing known AG-modifying enzymes, including the three most common such enzymes found in Enterobacteriaceae. ACHN-490 inhibited the growth of AG-resistant Enterobacteriaceae (MIC(90), ≤4 μg/ml), with the exception of Proteus mirabilis and indole-positive Proteae (MIC(90), 8 μg/ml and 16 μg/ml, respectively). ACHN-490 was more active alone in vitro against Pseudomonas aeruginosa and Acinetobacter baumannii isolates with AG-modifying enzymes than against those with altered permeability/efflux. The MIC(90) of ACHN-490 against AG-resistant staphylococci was 2 μg/ml. Due to its promising in vitro and in vivo profiles, ACHN-490 has been advanced into clinical development as a new antibacterial agent.

We determined the in vitro MIC of arbekacin against 200 Acinetobacter isolates recovered from wounded soldiers. The median MIC was 2 microg/ml (range, 0.5 to > 64 microg/ml). A total of 97.5% of the isolates had arbekacin MICs of < 8 microg/ml and 86.5% had MICs of < or = 4 microg/ml. There was no association between the arbekacin MIC and susceptibility to 16 other antibiotics or the specimen source (P = 0.7239). Synergy testing suggested an enhanced effect of arbekacin-carbapenem combinations.

Gallstones form when the ratio of bile cholesterol to bile acids and phospholipids is elevated, causing cholesterol to precipitate. Physical inactivity is hypothesized to increase gallstone development, but experimental evidence supporting this is lacking, and potential mechanisms for the antilithogenic effects of exercise have not been described. The purpose of this study was to examine the effect of endurance exercise training on gallstone formation and the expression of genes involved in bile cholesterol metabolism in gallstone-sensitive (C57L/J) mice. At 10 wk, 50 male mice began a lithogenic diet and were randomly assigned to an exercise-training (EX) or sedentary (SED) group (n = 25 per group). Mice in the EX group ran on a treadmill at approximately 15 m/min for 45 min/day for 12 wk. At the time animals were euthanized, gallstones were collected, pooled by group, and weighed. The weight of the gallstones was 2.5-fold greater in the SED mice compared with EX mice (143 vs. 57 mg, respectively). In the EX mice, hepatic expression of the low-density lipoprotein receptor (LDLr), scavenger receptor class B type 1 (SRB1), and sterol 27 hydroxylase (Cyp27) was increased by approximately 2-fold (P < 0.05 for each). The LDLr and SRB1 increase cholesterol clearance by low-density lipoprotein and high-density lipoprotein particles, respectively, while Cyp27 promotes the catabolism of cholesterol to bile acids. Taken together, these data indicate that exercise promotes changes in hepatic gene expression that increase cholesterol uptake by the liver but simultaneously increase the catabolism of cholesterol to bile acids, effectively reducing cholesterol saturation in the bile. This suggests a mechanism by which exercise improves cholesterol clearance from the circulation while simultaneously inhibiting gallstone formation.

Respiratory syncytial virus (RSV)-induced chemokine gene expression occurs through the activation of a subset of transcription factors, including Interferon Regulatory Factor (IRF)-3. In this study, we have investigated the signaling pathway leading to RSV-induced IRF-3 activation and whether it is mediated by intracellular reactive oxygen species (ROS) generation. Our results show that RSV infection induces expression and catalytic activity of IKKepsilon, a noncanonical IKK-like kinase. Expression of a kinase-inactive IKKepsilon blocks RSV-induced IRF-3 serine phosphorylation, nuclear translocation and DNA-binding, leading to inhibition of RANTES gene transcription, mRNA expression and protein synthesis. Treatment of alveolar epithelial cells with antioxidants or with NAD(P)H oxidase inhibitors abrogates RSV-induced chemokine secretion, IRF-3 phosphorylation and IKKepsilon induction, indicating that ROS generation plays a fundamental role in the signaling pathway leading to IRF-3 activation, therefore, identifying a novel molecular target for the development of strategies aimed to modify the inflammatory response associated with RSV infection of the lung.

Platelet interactions with adhesive ligands exposed at sites of vascular injury initiate the normal hemostatic response but may also lead to arterial thrombosis. Platelet membrane glycoprotein (GP)VI is a key receptor for collagen. Impairment of GPVI function in mice results in a long-term antithrombotic protection and prevents neointimal hyperplasia following arterial injury. On the other hand, GPVI deficiency in humans or mice does not result in serious bleeding tendencies. Blocking GPVI function may thus represent a new and safe antithrombotic approach, but no specific, potent anti-GPVI directed at the human receptor is yet available. Our aim was to produce accessible antagonists of human GPVI to evaluate the consequences of GPVI blockade. Amongst several monoclonal antibodies to the extracellular domain of human GPVI, one, 9O12.2, was selected for its capacity to disrupt the interaction of GPVI with collagen in a purified system and to prevent the adhesion of cells expressing recombinant GPVI to collagen and collagen-related peptides (CRP). While 9O12.2 IgGs induced platelet activation by a mechanism involving GPVI and Fc gamma RIIA, 9O12.2 Fab fragments completely blocked collagen-induced platelet aggregation and secretion from 5 microg mL-1 and fully prevented CRP-induced activation from 1.5 microg mL-1. 9O12.2 Fabs also inhibited the procoagulant activity of collagen-stimulated platelets and platelet adhesion to collagen in static conditions. Furthermore, 9O12.2 Fabs impaired platelet adhesion, and prevented thrombi formation under arterial flow conditions. We thus describe here for the first time a functional monoclonal antibody to human GPVI and demonstrate its effect on collagen-induced platelet aggregation and procoagulant activity, and on thrombus growth.

The CD2 family is a growing family of Ig domain-containing cell surface proteins involved in lymphocyte activation. Here we describe the cloning and expression analysis of a novel member of this family, B lymphocyte activator macrophage expressed (BLAME). BLAME shares the structural features of the CD2 family containing an IgV and IgC2 domain and clusters with the other family members on chromosome 1q21. Quantitative PCR and Northern blot analysis show BLAME to be expressed in lymphoid tissue and, more specifically, in some populations of professional APCs, activated monocytes, and DCS: Retroviral forced expression of BLAME in hematopoietic cells of transplanted mice showed an increase in B1 cells in the peripheral blood, spleen, lymph nodes, and, most strikingly, in the peritoneal cavity. These cells do not express CD5 and are CD23(low)Mac1(low), characteristics of the B1b subset. BLAME may therefore play a role in B lineage commitment and/or modulation of signal through the B cell receptor.

The specific activity of 17 beta-hydroxysteroid oxidoreductase (17-HOR) with estradiol-17 beta (E2), estrone (E1) and testosterone (T), as well as that of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) were measured in homogenates of CF-1 mouse placenta during the latter half of pregnancy. 17-HOR activity with E2 and T increased over 100-fold between days 9 and 12, and 3- to 4-fold between days 15 and 19, with no further change to day 21. In contrast, activity with E1 increased 39-fold between days 9 and 12, 3.8-fold between days 15 and 19 but then decreased between days 19 and 21. The E2/T activity ratio was constant while the E2/E1 ratio increased between days 9 and 21. LDH increased 2-fold between days 9 and 12 with no further increase to day 19. MDH was constant from day 9 to 19. Activity with E2 was inhibited by T, 5 alpha-dihydrotestosterone (5 alpha-DHT) and DHA but not by E1, androstenedione (A) or 20 alpha-dihydroprogesterone. Activity with T was inhibited by E2, 5 alpha-DHT and DHA, but not by A. In contrast, activity with E1 was inhibited by A and DHA but not by E2, T or 5 alpha-DHT. The results suggest placental 17-HOR is developmentally regulated. Although the results are also suggestive of multiple forms of 17-HOR, a single enzyme with an ordered kinetic mechanism cannot be ruled out.