C-8 Modifications of 3-alkyl-1,8-dibenzylxanthines as inhibitors of human cytosolic phosphoenolpyruvate carboxykinase

New modifications on the C-8 4-aminobenzyl unit of the previously reported 3-alkyl-1,8-dibenzylxanthine inhibitors of cPEPCK are presented. The most active compound reported here is the 5-chloro-1,3-dimethyl-1H-pyrazole-4-sulfonic acid amide derivative 2 with an IC(50) of 0.29+/-0.08 microM. An X-ray analysis of a heteroaromatic sulfonamide is presented showing a new pi-pi interaction.     

An interdisciplinary knowledge translation intervention in long-term care: Study protocol for the vitamin D and osteoporosis study (ViDOS) pilot cluster randomized controlled trial

ABSTRACT: BACKGROUND: Knowledge translation (KT) research in long-term care (LTC) is still in its early stages. This protocol describes the evaluation of a multifaceted, interdisciplinary KT intervention aimed at integrating evidence-based osteoporosis and fracture prevention strategies into LTC care processes. Methods and design The Vitamin D and Osteoporosis Study (ViDOS) is underway in 40 LTC homes (n = 21 intervention, n = 19 control) across Ontario, Canada. The primary objectives of this study are to assess the feasibility of delivering the KT intervention, and clinically, to increase the percent of LTC residents prescribed [greater than or equal to]800 IU of vitamin D daily. Eligibility criteria are LTC homes that are serviced by our partner pharmacy provider and have more than one prescribing physician. The target audience within each LTC home is the Professional Advisory Committee (PAC), an interdisciplinary team who meets quarterly. The key elements of the intervention are three interactive educational sessions led by an expert opinion leader, action planning using a quality improvement cycle, audit and feedback reports, nominated internal champions, and reminders/point-of-care tools. Control homes do not receive any intervention, however both intervention and control homes received educational materials as part of the Ontario Osteoporosis Strategy. Primary outcomes are feasibility measures (recruitment, retention, attendance at educational sessions, action plan items identified and initiated, internal champions identified, performance reports provided and reviewed), and vitamin D ([greater than or equal to]800 IU/daily) prescribing at 6 and 12 months. Secondary outcomes include the proportion of residents prescribed calcium supplements and osteoporosis medications, and falls and fractures. Qualitative methods will examine the experience of the LTC team with the KT intervention. Homes are centrally randomized to intervention and control groups in blocks of variable size using a computer generated allocation sequence. Randomization is stratified by home size and profit/nonprofit status. Prescribing data retrieval and analysis are performed by blinded personnel. DISCUSSION: Our study will contribute to an improved understanding of the feasibility and acceptability of a multifaceted intervention aimed at translating knowledge to LTC practitioners. Lessons learned from this study will be valuable in guiding future research and understanding the complexities of translating knowledge in LTC. Trial registration ClinicalTrials.gov NCT01398527.     

Drosophila telomeres: A variation on the telomerase theme

In Drosophila, the role of telomerase is carried out by three specialized retrotransposable elements, HeT-A, TART and TAHRE. Telomeres contain long tandem head-to-tail arrays of these elements. Within each array, the three elements occur in random, but polarized, order. Some are truncated at the 5' end, giving the telomere an enriched content of the large 3' untranslated regions, which distinguish these telomeric elements from other retrotransposons. Thus, Drosophila telomeres resemble other telomeres because they are long arrays of repeated sequences, albeit more irregular arrays than those produced by telomerase. The telomeric retrotransposons are reverse-transcribed directly onto the end of the chromosome, extending the end by successive transpositions. Their transposition uses exactly the same method by which telomerase extends chromosome ends--copying an RNA template. In addition to these similarities in structure and maintenance, Drosophila telomeres have strong functional similarities to other telomeres and, as variants, provide an important model for understanding general principles of telomere function and evolution.     

X-ray structures of two xanthine inhibitors bound to PEPCK and N-3 modifications of substituted 1,8-dibenzylxanthines

The analysis of the X-ray structures of two xanthine inhibitors bound to PEPCK and a comparison to the X-ray structure of GTP bound to PEPCK are reported. The SAR at N-1, N-7 and developing SAR at C-8 are consistent with information gained from the X-ray structures of compounds 1 and 2 bound to PEPCK. Representative N-3 modifications of compound 2 that led to the discovery of 3-cyclopropylmethyl and its carboxy analogue as optimal N-3 groups are presented.     

RNA interference has a role in regulating Drosophila telomeres

Unlike many other organisms, Drosophila maintains its telomeres by the transposition of retrotransposons to chromosome ends. Recent work shows that proteins in the RNA interference pathway specifically regulate the expression of these retrotransposons and frequency of transposition in germline cells, but do not affect retrotransposon expression or telomere function in the soma.     

Structure of the Drosophila HeT-A transposon: a retrotransposon-like element forming telomeres

Telomeres of Drosophila appear to be very different from those of other organisms. A transposable element, HeT-A, plays a major role in forming telomeres and may be the sole structural element, since telomerase-generated repeats are not found. HeT-A transposes only to chromosome ends. It appears to be a retrotransposon but has novel structural features, which may be related to its telomere functions. A consensus sequence from cloned HeT-A elements defines an element of 6 kb. The coding region has retrotransposon-like overlapping open reading frames (ORFs) with a –1 frameshift in a sequence resembling the frameshift region of the mammalian HIV-1 retrovirus. Both the HeT-A ORFs contain motifs suggesting RNA binding. HeT-A-specific features include a long non-coding region, 3 of the ORFs, which makes up about half of the element. This region has a regular array of imperfect sequence repeats and ends with oligo(A), marking the end of the element and suggesting a polyadenylated RNA transposition intermediate. This 3 repeat region may have a structural role in heterochromatin. The most distal part of each complete HeT-A on the chromosome, the region 5 of the ORFs, has unusual conserved features, which might produce a terminal structure for the chromosome.     

Modified 3-alkyl-1,8-dibenzylxanthines as GTP-competitive inhibitors of phosphoenolpyruvate carboxykinase

The first non-substrate like inhibitors of human cytosolic phosphoenolpyruvate carboxykinase (PEPCK) competitive with GTP are reported. An effort to discover orally active compounds that improve glucose homeostasis in Type 2 diabetics by reversibly inhibiting PEPCK led to the discovery of 1-allyl-3-butyl-8-methylxanthine (5). We now report modifications at N-1 and C-8 that improved the in vitro activity of the initial xanthine HTS hit by 100-fold and a developing SAR for this class of inhibitor.     

Seminested PCR for the detection and analysis of flue-cured tobacco (Nicotiana tabacum) expressing a chitinase transgene

Standard PCR was ineffective in detecting a baculovirus-derived chitinase transgene in the T1 generation of chitinase-expressingNicotiana tabacum cv. CF80 after leaves were flue-cured at high temperatures. Consequently, a seminested PCR method was developed using fresh leaves from T2 generation plants also expressing the chitinase protein. Seminested PCR was highly effective in detecting the chitinase transgene in fresh leaves ofN. tabacum cvs. Xanthi-nc and K326 and in both fresh and flue-cured leaves ofN. tabacum cv. CF80.