Discovery of an Acyclic Nucleoside Phosphonate that Inhibits Mycobacterium tuberculosis ThyX Based on the Binding Mode of a 5‐Alkynyl Substrate Analogue

The urgent need for new antibiotics poses a challenge to target un(der)exploited vital cellular processes. Thymidylate biosynthesis is one such process due to its crucial role in DNA replication and repair. Thymidylate synthases (TS) catalyze a crucial step in the biosynthesis of thymidine 5‐triphosphate (TTP), an elementary building block required for DNA synthesis and repair. To date, TS inhibitors have only been successfully applied in anticancer therapy due to their lack of specificity for antimicrobial versus human enzymes. However, the discovery of a new family of TS enzymes (ThyX) in a range of pathogenic bacteria that is structurally and biochemically different from the “classic” TS (ThyA) has opened the possibility to develop selective ThyX inhibitors as potent antimicrobial drugs. Here, the interaction of the known inhibitor 5‐(3‐octanamidoprop‐1yn‐1yl)‐2′‐deoxyuridine‐5′‐monophosphate ( 1 ) with Mycobacterium tuberculosis ThyX enzyme is explored using molecular modeling starting from published crystal structures, with further confirmation through NMR experiments. While the deoxyuridylate (dUMP) moiety of compound 1 occupies the cavity of the natural substrate in ThyX, the rest of the ligand (the “5‐alkynyl tail”) extends to the outside of the enzyme between two of its four subunits. The hydrophobic pocket that accommodates the alkyl part of the tail is formed by displacement of Tyr 44.C, Tyr 108.A and Lys 165.A. Changes to the resonance of the Lys 165 NH₃ group upon ligand binding were monitored in a titration experiment by 2D HISQC NMR. Guided by the results of the modeling and NMR studies, and inspired by the success of acyclic antiviral nucleosides, compounds where a 5‐alkynyl uracyl moiety is coupled to an acyclic nucleoside phosphonate (ANP) were synthesized and evaluated. Of the compounds evaluated, sodium (6‐(5‐(3‐octanamidoprop‐1‐yn‐1‐yl)‐2,4‐dioxo‐3,4‐dihydropyrimidin‐1(2H)‐yl)hexyl)phosphonate ( 3 e ) exhibited 43 % of inhibitory effect on ThyX at 50 μM . While only modest activity was achieved, this is the first example of an ANP inhibiting ThyX, and these results can be used to further guide structural modifications to this class to develop more potent compounds with potential application as antibacterial agents acting through a novel mechanism of action.     

The influence of user-generated content on traveler behavior: An empirical investigation on the effects of e-word-of-mouth to hotel online bookings

The increasing use of web 2.0 applications has generated numerous online user reviews. Prior studies have revealed the influence of user-generated reviews on the sales of products such as CDs, books, and movies. However, the influence of online user-generated reviews in the tourism industry is still largely unknown both to tourism researchers and practitioners. To bridge this knowledge gap in tourism management, we conducted an empirical study to identify the impact of online user-generated reviews on business performance using data extracted from a major online travel agency in China. The empirical findings show that traveler reviews have a significant impact on online sales, with a 10 percent increase in traveler review ratings boosting online bookings by more than five percent. Our results highlight the importance of online user-generated reviews to business performance in tourism.     

Rodney Cotterill,Enchanted Looms: Conscious Networks in Brains and Computers.

Minds and Machines -     

Robotic Assembly of Space Solar-Power Facilities

This paper profiles research relating to the robotic assembly, inspection, and maintenance of space solar-power facilities. Free-flying robots, fixed-base manipulators, and attached mobile manipulators are examined, the technical challenges facing them are outlined, and their roles in the construction process are illuminated. Themes include autonomous materials delivery, warehousing, large-scale payload handling and mating, payload attachment in confined spaces, and inspection. Research has addressed a fraction of the technologies needed to perform reliable autonomous assembly, inspection, and maintenance. Areas in need of further development are examined and potential research is outlined. Current technology cannot fulfill the requirements of orbital construction. The research and development needed can be completed in the near future, and substantive assembly inspection and maintenance can be achieved.     

Is there an association between lateral preference and delinquent behavior?

Results of recent research suggests an association between left lateral preference and delinquent behavior. In this study the lateral preferences of 881 seven-year-old children were determined using behavioral indicators of hand and foot use. Mixed-handedness was associated with parent-reported problem behavior scores and self-reported delinquency scores at ages 13 and 15. However, preference for left hand and foot use was found to be unrelated to the delinquency measures. The distribution of lateral preferences in an identified delinquent group was not significantly different from the distribution in the sample remainder. The lack of an association between left preference and delinquency may be accounted for by an increased cultural acceptance of individual preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stenosis of the tubular neck: a possible mechanism for progressive renal failure

OBJECTIVE: To study the influence of continuous administration of heparin on platelet function in intensive care patients. DESIGN: Prospective, serial investigation. SETTING: Clinical investigation on a surgical and neurosurgical intensive care unit in a university hospital. PATIENTS: The study included 45 patients: 15 postoperative with patients sepsis (Acute Physiology and Chronic Health Evaluation II score between 15 and 25), 15 trauma patients (Injury Severity Score 15 to 25), and 15 neurosurgical patients. INTERVENTIONS: Management of the patients was carried out according to the guidelines for modern intensive care therapy. Sepsis and trauma patients received standard (unfractionated) heparin continuously [aim: an activated partial thromboplastin time (aPTT) approximately 2.0 times normal value; sepsis-heparin and trauma-heparin patients], whereas neurosurgical patients received no heparin (neurosurgical patients). MEASUREMENTS AND RESULTS: From arterial blood samples, platelet aggregation was measured by the turbidimetric method. Platelet aggregation was induced by adenosine diphosphate (ADP; 2.0 mumol/l), collagen (10 micrograms/ml), and epinephrine (25 mumol/l). Measurements were carried out on the day of diagnosis of sepsis or 12 h after hemodynamic stabilization (trauma and neurosurgery patients) (baseline) and during the next 5 days at 12.00 noon. Standard coagulation parameters [platelet count and fibrinogen and antithrombin III (AT III) plasma concentrations] were also monitored. Heparin 4-10 U/kg per h (mean dose: approximately 500 U/h) was necessary to reach an aPTT of about 2.0 times normal. Platelet count was highest in the neurosurgical patients, but it did not decrease after heparin administration to the trauma and sepsis patients. AT III and fibrinogen plasma levels were similar in the three groups of patients. In the sepsis group, platelet aggregation variables decreased significantly (e.g., epinephrine-induced maximum platelet aggregation:-45 relative % from baseline value). Platelet function recovered during the study and even exceeded baseline values (e.g., ADP-induced maximum platelet aggregation: +42.5 relative % from baseline value). Continuous heparinization did not blunt this increase of platelet aggregation variables. In the heparinized trauma patients, platelet aggregation variables remained almost stable and were no different to platelet aggregation data in the untreated neurosurgical patients. CONCLUSIONS: Continuous administration of heparin with an average dose of approximately 500 U/h did not negatively influence platelet function in the trauma patients. Recovery from reduced platelet function in the sepsis group was not affected by continuous heparinization. Thus, continuous heparinization with this dose appears to be safe with regard to platelet function in the intensive care patient.     

Is local biotransformation the key to understanding the pharmacological activity of salicylates and gold drugs?

It is suggested that some drugs may be converted by inflammatory cells to yield active species. The transformation may be non-enzymatic, although being driven by the enzymatic production of highly reactive species which are normal products of activated leukocytes, such as singlet oxygen, hydrogen peroxide, hypochlorite, hydroxyl radical and nitric oxide. Drugs which may be transformed in this fashion are the anti-rheumatic gold complexes which may be converted either to aurocyanide or to Au(III) complexes by myeloperoxidase in polymorphonuclear leukocytes. Salicylate may also be activated by its oxidation to dihydroxybenzoates although evidence for its transformation is weaker than for the gold complexes.