In Vivo Antiviral Activity of 5-Amino-1-Methyl-3-β-D-Ribofuranosyl-Pyrazolo[4,3-d]Pyrimidin-7(6H)-One and Related Guanosine Analogues Prepared from Formycin

Abstract

A short and simple synthesis of 5-amino-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one, (7) was achieved from 7-amino-5-chloro-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidine (5), in two steps, first deamination of 5 with NOCI, followed by amination of 6 with MeOH/NH₃. Also, an efficient synthesis of 5-amino-1(or 2)-methyl-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one was accomplished from the corresponding 1 (or 2)-methyloxoformycin B in four steps by a sequence consisting of (i) 2′,3′,5′ acetylation with AC₂O, (ii) 5,7-chlorination with PhP(O)Cl₂, (iii) selective hydrolysis of the 7-chloro group with aqueous Na₂CO₃, (iv) followed by amination of the 5-chloro group with MeOH/NH₃. Single crystal X-ray analysis off 11 confirmed position 7 as the site of selective hydrolysis with Na₂CO₃. The three guanosine C-nucleosides prepared were evaluated for their ability to inhibit certain RNA and DNA viral replication in vitro and Semliki Forest virus infection in vivo. Only 5-amino-1-methyl-3-β-D-ribofuranosylpyrazolo[4,3-d]pyrimidin-7(6H)-one (13) provided protection (67% survivors, compared to 0% for placebo controls) against a lethal dose of Semliki Forest virus infection in mice. The antiviral effect of 13 is believed to be due to the enhancement of the host immune function.     

Towards a phylogeny and evolution of Acochlidia (Mollusca: Gastropoda: Opisthobranchia)

The Acochlidia are unique among opisthobranch gastropods in combining extremely high morphological and ecological diversity with modest species diversity. The phylogeny of acochlidians has never been addressed by cladistic means, as their evolution has remained unknown. This study gives a first overview on more than 150 biological and morphological characters that are potentially useful for phylogenetic analysis. Based on 107 characters, a parsimony analysis (PAUP) was performed for all 27 valid acochlidian species together with 11 (plus two) outgroup taxa. The resulting strict consensus tree shows a moderate overall resolution, with at least some bootstrap support for most resolved nodes. The Acochlidia are clearly monophyletic, and originate from an unresolved basal opisthobranch level. The Acochlidia split into the Hedylopsacea (Tantulum (Hedylopsis (Pseudunela (Strubellia (‘Acochlidium’, ‘Palliohedyle’))))) and Microhedylacea (Asperspina (Pontohedyle, ‘Parhedyle’, ‘Microhedyle’, (Ganitus, Paraganitus))). The formerly enigmatic Ganitidae, resembling sacoglossan opisthobranchs by having dagger‐like rachidian radular teeth, are likely to be highly derived microhedylids. The paraphyly of some of the traditionally recognized family level taxa induced a preliminary reclassification. From the phylogenetic hypothesis obtained, we conclude that the acochlidian ancestor was marine mesopsammic. The colonization of limnic systems occurred twice, independently: first in the Caribbean (with the development of the small interstitial Tantulum elegans), and second in the Indo‐Pacific, with a radiation of large‐sized benthic acochlidian species. The evolution of extraordinary reproductive features, such as hypodermic impregnation by a complex copulative aparatus in hedylopsaceans, cutaneous insemination via spermatophores in microhedylaceans, and gonochorism in Microhedylidae s.l. (including Ganitidae), is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 124–154.     

Triple Combination of Amantadine,Ribavirin, and Oseltamivir Is Highly Active and Synergistic against Drug Resistant Influenza Virus Strains In Vitro

The rapid emergence and subsequent spread of the novel 2009 Influenza A/H1N1 virus (2009 H1N1) has prompted the World Health Organization to declare the first pandemic of the 21^st century, highlighting the threat of influenza to public health and healthcare systems. Widespread resistance to both classes of influenza antivirals (adamantanes and neuraminidase inhibitors) occurs in both pandemic and seasonal viruses, rendering these drugs to be of marginal utility in the treatment modality. Worldwide, virtually all 2009 H1N1 and seasonal H3N2 strains are resistant to the adamantanes (rimantadine and amantadine), and the majority of seasonal H1N1 strains are resistant to oseltamivir, the most widely prescribed neuraminidase inhibitor (NAI). To address the need for more effective therapy, we evaluated the in vitro activity of a triple combination antiviral drug (TCAD) regimen composed of drugs with different mechanisms of action against drug-resistant seasonal and 2009 H1N1 influenza viruses. Amantadine, ribavirin, and oseltamivir, alone and in combination, were tested against amantadine- and oseltamivir-resistant influenza A viruses using an in vitro infection model in MDCK cells. Our data show that the triple combination was highly synergistic against drug-resistant viruses, and the synergy of the triple combination was significantly greater than the synergy of any double combination tested (P<0.05), including the combination of two NAIs. Surprisingly, amantadine and oseltamivir contributed to the antiviral activity of the TCAD regimen against amantadine- and oseltamivir-resistant viruses, respectively, at concentrations where they had no activity as single agents, and at concentrations that were clinically achievable. Our data demonstrate that the TCAD regimen composed of amantadine, ribavirin, and oseltamivir is highly synergistic against resistant viruses, including 2009 H1N1. The TCAD regimen overcomes baseline drug resistance to both classes of approved influenza antivirals, and thus may represent a highly active antiviral therapy for seasonal and pandemic influenza.     

Biphenyl amide p38 kinase inhibitors 2: Optimisation and SAR

The biphenyl amides are a novel series of p38 MAP kinase inhibitors. Structure-activity relationships of the series against p38alpha are discussed with reference to the X-ray crystal structure of an example. The series was optimised rapidly to a compound showing oral activity in an in vivo disease model.     

Introns and reading frames: correlation between splicing sites and their codon positions

Computer analyses of the entire GenBank database were conducted to examine correlation between splicing sites and codon positions in reading frames. Intron insertion patterns (i.e., splicing site locations with respect to codon positions) have been analyzed for all of the 74 codons of all the eukaryote taxonomic groups: primates, rodents mammals, vertebrates, invertebrates, and plants. We found that reading frames are interrupted by an intron at a codon boundary (as opposed to the middle of a codon) significantly more often than expected. This observation is consistent with the exon shuffling hypothesis, because exons that end at codon boundaries can be concatenated without causing a frame shift and thus are evolutionarily advantageous. On the other hand, when introns interrupt at the middles of codons, they exist in between the first and second bases much more frequently than between the second and third bases, despite the fact that boundaries between the first and second bases of codons are generally far more important than those between the second and third bases. The reason for this is not clear and yet to be explained. We also show that the length of an exon is a multiple of 3 more frequently than expected. Furthermore, the total length of two consecutive exons is also more frequently a multiple of 3. All the observations above are consistent with results recently published by Long, Rosenberg, and Gilbert (1995).      

Metabolome and metaboproteome remodeling in nuclear reprogramming

Nuclear reprogramming resets differentiated tissue to generate induced pluripotent stem (iPS) cells. While genomic attributes underlying reacquisition of the embryonic-like state have been delineated, less is known regarding the metabolic dynamics underscoring induction of pluripotency. Metabolomic profiling of fibroblasts vs. iPS cells demonstrated nuclear reprogramming-associated induction of glycolysis, realized through augmented utilization of glucose and accumulation of lactate. Real-time assessment unmasked downregulated mitochondrial reserve capacity and ATP turnover correlating with pluripotent induction. Reduction in oxygen consumption and acceleration of extracellular acidification rates represent high-throughput markers of the transition from oxidative to glycolytic metabolism, characterizing stemness acquisition. The bioenergetic transition was supported by proteome remodeling, whereby 441 proteins were altered between fibroblasts and derived iPS cells. Systems analysis revealed overrepresented canonical pathways and interactome-associated biological processes predicting differential metabolic behavior in response to reprogramming stimuli, including upregulation of glycolysis, purine, arginine, proline, ribonucleoside and ribonucleotide metabolism, and biopolymer and macromolecular catabolism, with concomitant downregulation of oxidative phosphorylation, phosphate metabolism regulation, and precursor biosynthesis processes, prioritizing the impact of energy metabolism within the hierarchy of nuclear reprogramming. Thus, metabolome and metaboproteome remodeling is integral for induction of pluripotency, expanding on the genetic and epigenetic requirements for cell fate manipulation.     

Butterflies on the brink: habitat requirements for declining populations of the marsh fritillary (Euphydryas aurinia) in SW England

1. The marsh fritillary Euphydryas aurinia is one of our most endangered butterflies, and the only to be protected under European legislation as well as British. It persists in fragile subpopulations threatened by habitat fragmentation and degradation. 2. A combination of swaling and cattle grazing are accepted to be best practice for managing wet, unimproved grasslands??the favoured habitat for E. aurinia in Cornwall. These two well-endorsed methods of management were used to increase and improve the quality of habitat for E. aurinia over a 5 years period, 2004?C2008, at a stronghold network of habitat patches in mid Cornwall, south-west England. 3. Analyses of adult and larval densities over 5 years in fifty-four transects across nine sites found E. aurinia to favour habitat patches with higher densities of the larval food plant (Devil??s-bit scabious Succisa pratensis), higher sward height in autumn, and intermediate optimum levels of stock grazing. 4. Main findings indicated most sites experienced significant declines in numbers. Unfavourable weather in the last 2 years of monitoring was likely to have had a significant impact on the response of individual subpopulations to habitat management though poor recovery rates may also reflect a time-lag in colonisation events after habitat improvement has occurred. 5. Habitat management produced an improvement, albeit an inconsistent improvement in habitat variables across patches??S. pratensis shows a clear recovery at some sites. Autumn sward height increased significantly at one site, and a quadratic relationship between stock grazing and important habitat variables has been found which will aid further improvement over all sites for the long term persistence of E. aurinia.     

Anti-cowpox virus activities of certain adenosine analogs, arabinofuranosyl nucleosides, and 2'-fluoro-arabinofuranosyl nucleosides

Nucleoside analogs were investigated for their potential to inhibit cowpox virus (a surrogate for variola and monkeypox viruses) in cell culture and in lethal respiratory infections in mice. Cell culture antiviral activity was determined by plaque reduction assays, with cytotoxicity determined by cell proliferation assays. Selectivity indices (SI's, 50% cytotoxic concentration divided by 50% virus-inhibitory concentration) were determined for 15 compounds. Three arabinofuranosyl (Ara) nucleosides showed activity in mouse mammary tumor (C127I) cells: guanine (Ara-G), thymine (Ara-T), and adenine (Ara-A) with SI's of 113, 61, and 95, respectively. The 2'-fluoro-Ara nucleosides of 5-F-cytosine (FIAC), 5-methyluracil (FMAU), and 5-iodouracil (FIAU) exhibited SI's of 148, 77, and 29, respectively. Other potent compounds included cidofovir (a positive control) and 3'-O-methyladenosine, with SI values of 164 and 56, respectively. In general, assays performed in African green monkey kidney (Vero) cells produced lower SI's than in C127I cells, except for 5-iodo-2'-deoxyuridine (IDU) which had an SI of > 71 in Vero cells and 3.1 in C127I cells. Intranasal infection of mice with cowpox virus was followed a day later by twice daily intraperitoneal treatment with compounds for 5 days. Ara-A was active at 300 mg/kg/day (40% survival), FMAU at 100 mg/kg/day (70% survival), and cidofovir (given for 1 day only) at 100 mg/kg (80-100% survival). None of the other compounds, including IDU, prevented death nor delayed the time to death. Cidofovir had the best potential for treating orthopoxvirus infections of those tested.     

Phylogenetic analysis using insertion sequence fingerprinting in Escherichia coli

Chromosomal DNA from 23 closely related, pathogenic strains of Escherichia coli was digested and probed for the insertion sequences IS1, IS2, IS4, IS5, and IS30. Under the assumption that elements residing in DNA restriction fragments of the same apparent length are identical by descent, parsimony analysis of these characters yielded a unique phylogenetic tree. This analysis not only distinguished among bacterial strains that were otherwise identical in their biochemical characteristics and enzyme electrophoretic mobilities, but certain aspects of the topology of the tree were consistent across several unrelated insertion elements. The distribution of IS elements was then reexamined in light of the inferred phylogenetic relationships to investigate the biological properties of the elements, such as rates of insertion and deletion, and to discover apparent recombinational events. The analysis shows that the pattern of distribution of insertion elements in the bacterial genome is sufficiently stable for epidemiological studies. Although the rate of recombination by conjugation has been postulated to be low, at least two such events appear to have taken place.