Pilot study of an EST approach of the coccolithophorid Emiliania huxleyi during a virus infection

Blooms of the coccolithophorid Emiliania huxleyi can be infected by viruses, which can lead to bloom-termination. This pilot study used an expressed sequence tag (EST) approach to get a first view of gene-expression changes that occur during viral infection of E. huxleyi. cDNA libraries were constructed from uninfected cultures and 6, 12, and 24 h after infection with E. huxleyi-specific virus 86 (EhV-86). From each library 60-90 ESTs were randomly selected and annotated manually with PhyloGena. Viral genes were identified using BLAST-Search of the known viral genome. The data of this study show, that 6 h after viral infection the algal transcriptome changed significantly although few viral transcripts were present. At this point, changes mainly concerned transcripts related to photosynthesis and protein metabolism. However, after 24 h viral transcripts were most abundant. Viral transcripts found at this stage of viral infection encode proteins involved in protein degradation, nucleic acid degradation, transcription and replication.

Comparative Analysis of Endodontic Pathfinders

Because no scientific literature exists regarding endodontic pathfinders, the aim of this study was to compare such instruments. Ten different pathfinder-type files were analyzed with respect to dimensional characteristics, pitch, and rigidity; efficiency, wear, and distortion were assessed by using an in vitro simulation exercise. SEM cross-sections and tip images were obtained and analyzed. To assess efficacy and distortion, 10 operators attempted to achieve patency with the files in small, S-shaped canals in acrylic blocks. Trends in canal negotiation efficiency and file distortion were recorded. Results showed that the Hi-5 (Miltex, York, PA) and C+ files (Dentsply/Maillefer, Johnson City, TN) were the least flexible, whereas the Pathfinder CS (SybronEndo, Glendora, CA) and Pathfinder SS (SybronEndo) files were the most. Pathfinder SS, S finder (JSDental/Sendoline, Ridgefield, CT), and D finder (Mani, Tochigi-ken, Japan) were the most efficient during the simulation exercise. Within the parameters of this study, pitch, taper, cross-section, heat tempering, metal type, tip geometry, and operator skills all influenced pathfinder efficiency.

Use of microarrays to assess viral diversity: from genotype to phenotype

The diversity among the coccolithovirus strains held in the Plymouth Virus Collection (PVC) was assessed using three complementary techniques: phylogeny based on DNA polymerase and major capsid protein gene sequence; host range; and a new, microarray-based genome-wide approach. The PVC is composed of three groups of strains that are geographically and temporally distinct. Virus strains clustered according to these groups in all three diversity assessments. Furthermore, the microarray approach based on genomic content showed that two strains, previously considered as identical to others in the PVC, are actually distinct. These results show the importance of genome-wide surveys for assessing strain diversity. Not only has the microarray provided an alternative to the phylogeny-derived pattern for virus evolution, it has also begun to provide some clues to the genes that may be responsible for the different phenotypes displayed by these viruses.

Use of a novel and highly selective oxytocin receptor antagonist to characterize uterine contractions in the rat

Spontaneous and induced uterine contractions in the rat were found to be inhibited by a novel and selective oxytocin receptor antagonist GSK221149A (3R,6R)-3-Indan-2-yl-1-[(1R)-1-(2-methyl-1,3-oxazol-4-yl)-2-morpholin-4-yl-2-oxoethyl]-6-[(1S)-1-methylpropyl]-2,5-piperazinedione. GSK221149A displayed nanomolar affinity (K(i) = 0.65 nM) for human recombinant oxytocin receptors with >1,400-fold selectivity over human V1a, V1b, and V2 receptors. GSK221149A had similar affinity (K(i) = 4.1 nM) and selectivity for native oxytocin receptors from rat and produced a functional, competitive block of oxytocin-induced contractions in isolated rat myometrial strips with a pA(2) value of 8.18. Intravenous administration of GSK221149A produced a dose-dependent decrease in oxytocin-induced uterine contractions in anesthetized rats with an ID(50) = 0.27 +/- 0.60 mg/kg (corresponding plasma concentrations were 88 ng/ml). Oral administration of GSK221149A (5 mg/kg) was effective in inhibiting oxytocin-induced uterine contractions after single and multiple (4-day) dosing. Spontaneous uterine contractions in late-term pregnant rats (19-21 days gestation) were significantly reduced by intravenous administration of 0.3 mg/kg of GSK221149A. These results provide further evidence that selective oxytocin receptor antagonism may offer an effective treatment for preterm labor.

Expression of a novel marine viral single-chain serine palmitoyltransferase and construction of yeast and mammalian single-chain chimera

The genus Coccolithovirus is a recently discovered group of viruses that infect the globally important marine calcifying microalga Emiliania huxleyi. Surprisingly, the viral genome contains a cluster of putative sphingolipid biosynthetic genes not found in other viral genus. To address the role of these genes in viral pathogenesis, the ehv050 gene predicted to encode a serine palmitoyltransferase (SPT), the first and rate-limiting enzyme of sphingolipid biosynthesis, was expressed and characterized in Saccharomyces cerevisiae. We show that the encoded protein is indeed a fully functional, endoplasmic reticulum-localized, single-chain SPT. In eukaryotes SPT is a heterodimer comprised of long chain base 1 (LCB1) and LCB2 subunits. Sequence alignment and mutational analysis showed that the N-terminal domain of the viral protein most closely resembled the LCB2 subunit and the C-terminal domain most closely resembled the LCB1 subunit. Regardless of whether the viral protein was expressed as a single polypeptide or as two independent domains, it exhibited an unusual preference for myristoyl-CoA rather than palmitoyl-CoA. This preference was reflected by the increased presence of C16-sphingoid bases in yeast cells expressing the viral protein. The occurrence of a single-chain SPT suggested to us that it might be possible to create other fusion SPTs with unique properties. Remarkably, when the two subunits of the yeast SPT were thus expressed, the single-chain chimera was functional and displayed a novel substrate preference. This suggests that expression of other multisubunit membrane proteins as single-chain chimera could provide a powerful approach to the characterization of integral membrane proteins.

2,5-diketopiperazines as potent, selective, and orally bioavailable oxytocin antagonists. 3. Synthesis, pharmacokinetics, and in vivo potency

A short, efficient, and highly stereoselective synthesis of a series of (3R,6R,7R)-2,5-diketopiperazine oxytocin antagonists and their pharmacokinetics in rat and dog is described. Prediction of the estimated human oral absorption (EHOA) using measured lipophilicity (CHI log D) and calculated size (cMR) has allowed us to rank various 2,5-diketopiperazine templates and enabled us to focus effort on those templates with the greatest chance of high bioavailability in humans. This rapidly led to the 2',4'-difluorophenyl-dimethylamide 25 and the benzofuran 4 with high levels of potency (pK(i)) and good bioavailability in the rat and dog. Dimethylamide 25 is more potent (>20-fold) than 4 in vivo and has a high degree of selectivity toward the vasopressin receptors, >10,000 for hV1a/hV1b and approximately 500 for hV2. It has a good Cyp450 profile with no time dependent inhibition and was negative in the genotoxicity screens with a satisfactory oral safety profile in rats.

Locus-specific gene expression pattern suggests a unique propagation strategy for a giant algal virus

Emiliania huxleyi virus strain 86 is the largest algal virus sequenced to date and is unique among the Phycodnaviridae since its genome is predicted to contain six RNA polymerase subunit genes. We have used a virus microarray to profile the temporal transcription strategy of this unusual virus during infection. There are two distinct transcription phases to the infection process. The primary phase is dominated by a group of coding sequences (CDSs) expressed by 1 h postinfection that are localized to a subregion of the genome. The CDS of the primary group have no database homologues, and each is associated with a unique promoter element. The remainder of the CDSs are expressed in a secondary phase between 2 and 4 hours postinfection. Compartmentalized transcription of the two distinctive phases is discussed. We hypothesize that immediately after infection the nucleic acid of the virus targets the host nucleus, where primary-phase genes are transcribed by host RNA polymerase which recognizes the viral promoter. Secondary-phase transcription may then be conducted in the cytoplasm.

Analysis of two P-element enhancer-trap insertion lines that show expression in the giant fibre neuron of Drosophila melanogaster

The giant fibre system (GFS) of Drosophila is a simple neural circuit that mediates escape responses in adult flies. Here we report the initial characterization of two genes that are preferentially expressed in the GFS. Two P-element insertion lines, carrying the GAL4 transcriptional activator, were identified that exhibited pronounced expression in elements of the GFS and relatively low levels elsewhere within the adult central nervous system. Genomic DNA flanking the P-element insertion site was recovered from each of these lines, sequenced, and nearby transcripts identified and confirmed to exhibit GFS expression by in situ hybridization. This analysis revealed that these P-elements were in previously characterized genes. Line P[GAL4]-A307 has an insert in the gene short stop for which we have identified a novel transcript, while line P[GAL4]-141 has an insert in the transcription factor ken and barbie. Here we show that ken and barbie mutants have defects in escape behaviour, behavioural responses to visual stimuli and synaptic functions in the GFS. We have therefore revealed a neural role for a transcription factor that previously had no implicated neural function.

The response of Escherichia coli to exposure to the biocide polyhexamethylene biguanide

The global response of Escherichia coli to the broad-spectrum biocide polyhexamethylene biguanide (PHMB) was investigated using transcriptional profiling. The transcriptional analyses were validated by direct determination of the PHMB-tolerance phenotypes of derivatives of E. coli MG1655 carrying either insertionally inactivated genes and/or plasmids expressing the cognate open reading frames from a heterologous promoter in the corresponding chromosomally inactivated strains. The results showed that a wide range of genes was altered in transcriptional activity and that all of the corresponding knockout strains subsequently challenged with biocide were altered in tolerance. Of particular interest was the induction of the rhs genes and the implication of enzymes involved in the repair/binding of nucleic acids in the generation of tolerance, suggesting a novel dimension in the mechanism of action of PHMB based on its interaction with nucleic acids.

The coccolithovirus microarray: an array of uses

The Coccolithoviridae is a recently discovered family of giant algal viruses. Here, we review the genomic and transcriptomic characterization of this family based on the results generated from a coccolithovirus microarray. The microarray has been used to aid the annotation of the genome, to investigate the infection process at the transcriptional level and to assess the diversity in genomic content within the family.

Effects of radiation therapy on chondrocytes in vitro

The negative irradiation complications of growth loss leading to limb length asymmetry and pathological fracture incurred following radiation therapy in pediatric patients has led to a renewed interest in understanding the specific effects of irradiation on the growth plate and the surrounding bone. In the present report, we examined the radiation therapy effects on primary rat growth cartilage chondrocytes in order to determine the chondrocyte radiosensitivity relative to other bone cell constituents and tumor cells, the postirradiation temporal progression of radiation-induced alterations in chondrocyte function, and the time course for the functional restoration of chondrocyte pathways that drive the eventual recovery in growth function. We employed an in vitro primary rat costochondral growth cartilage cell culture model system to evaluate the radiation therapy effects on proliferative chondrocytes using serial radiation doses (0-20 Gy) that are well within the clinically relevant range. Following irradiation, all of the following occurred in a dose-dependent manner: proliferation decreased, cytotoxicity increased, several markers of apoptosis increased, markers of radiation-induced cellular differentiation increased, and cell synthetic activity was disturbed. Alterations in proliferation, cell death, and induction of apoptosis are likely due to a transient radiation-induced derangement of the parathyroid hormone-related protein-Indian hedgehog proliferation-maturation pathway. Alterations in cellular differentiation and cell synthetic activity are novel observations for chondrocytes. Further, these results correspond very well to our previous work in an in vivo Sprague-Dawley rat model, making this model particularly relevant to researching the radiation therapy effects on longitudinal growth.

Genome comparison of two Coccolithoviruses

Background

The Coccolithoviridae is a recently discovered family of viruses that infect the marine coccolithophorid Emiliania huxleyi. Following on from the sequencing of the type strain EhV-86, we have sequenced a second strain, EhV-163.

Results

We have sequenced approximately 80% of the EhV-163 genome, equating to more than 200 full length CDSs. Conserved and variable CDSs and a gene replacement have been identified in the EhV-86 and EhV-163 genomes.

Conclusion

The sequencing of EhV-163 has provided a wealth of information which will aid the re-annotating of the EhV-86 genome and identified a gene insertion in EhV-163.

2,5-diketopiperazines as potent, selective, and orally bioavailable oxytocin antagonists. 2. Synthesis, chirality, and pharmacokinetics

A short stereoselective synthesis of a series of chiral 7-aryl-2,5-diketopiperazines oxytocin antagonists is described. Varying the functionality and substitution pattern of substituents in the 7-aryl ring and varying the chirality of this exocyclic ring have produced potent oxytocin antagonists (pK(i) > 8.5). SAR and pharmacokinetic profiling of this series of (3R,6R,7R)-2,5-diketopiperazines together with the introduction of an ortho F group in the 7-aryl ring to improve rat pK has culminated in the 2',4'-difluorophenyldiketopiperazine derivative 37, a highly potent oxytocin antagonist against the human oxytocin receptor (pK(i) = 8.9) that has >1000-fold selectivity over all three vasopressin receptors V1a, V2, and V1b. It has good bioavailability (46%) in the rat and moderate bioavailability (13-31%) in the dog and is more active in vivo in the rat than atosiban (rat DR(10) = 0.44 mg/kg iv).

A randomized trial to assess childhood circumcision with the Plastibell device compared to a conventional dissection technique

A randomized trial of routine circumcision in children using the Plastibell device is described and compared to a dissection suturing technique. One hundred children were studied with a mean age of 4·7 years. The device was applicable to all boys up to the age of 8, and a few older. General discomfort was carefully assessed and slightly less common after Plastibell circumcision, but dysuria more so. No serious complication was encountered with either method; infection was slightly more common after the conventional procedure. Cosmetic results were similar for both methods. It is concluded that the Plastibell device is a satisfactory method for circumcising children of this age.

2,5-Diketopiperazines as potent and selective oxytocin antagonists 1: Identification, stereochemistry and initial SAR

This paper covers efforts to discover orally active potent and selective oxytocin antagonists. Screening pooled libraries identified a novel series of 2,5-diketopiperazine derivatives with antagonist activity at the human oxytocin receptor. We report the initial structure-activity relationship investigations and the determination of the stereochemistry of the most potent compounds.

Preliminary characterisation of repeat families in the genome of EhV-86, a giant algal virus that infects the marine microalga Emiliania huxleyi

EhV-86 is a large double stranded DNA virus with a 407,339 base pair circular genome that infects the globally important microalga Emiliania huxleyi. It belongs to a new genus of viruses termed the Coccolithoviridae within the algal virus family Phycodnaviridae. By plotting the EhV-86 genome against itself in a dot-plot analysis we revealed three families of distinctly different repeat sequences throughout its genome, designated Family A, B and C. Family A repeats are non-coding, found immediately upstream of 86 predicted coding sequences (CDSs) and are likely to play a crucial role in controlling the expression of the associated CDSs. Family B repeats are GC rich, coding and correspond to possible calcium binding sites in 22 proline-rich domains found in the protein products of eight predicted EhV-86 CDSs. Family C repeats are AT-rich, non-coding and are likely to form part of the origin of replication. We suggest that these repeat regions are of fundamental importance during virus propagation being involved with transcriptional control (Family A), virus adsorption/release (Family B) and DNA replication (Family C).

Evolutionary history of the Coccolithoviridae

We recently determined the genome sequence of the Coccolithoviridae strain Emiliania huxleyi virus 86 (EhV-86), a giant double-stranded DNA (dsDNA) algal virus from the family Phycodnaviridae that infects the marine coccolithophorid E. huxleyi. Here, we determine the phylogenetic relationship between EhV-86 and other large dsDNA viruses. Twenty-five core genes common to nuclear-cytoplasmic large dsDNA virus genomes were identified in the EhV-86 genome; sequence from eight of these genes were used to create a phylogenetic tree in which EhV-86 was placed firmly with the two other members of the Phycodnaviridae. We have also identified a 100-kb region of the EhV-86 genome which appears to have transferred into this genome from an unknown source. Furthermore, the presence of six RNA polymerase subunits (unique among the Phycodnaviridae) suggests both a unique evolutionary history and a unique lifestyle for this intriguing virus.

Natural history of asymptomatic bile duct stones at time of cholecystectomy

OBJECTIVES

There is little data on the natural history of asymptomatic bile duct stones and hence there is uncertainty on the management of asymptomatic bile duct stones discovered incidentally at the time of laparoscopic cholecystectomy. We retrospectively reviewed a group of patients who had previously underwent laparoscopic cholecystectomy, but who did not have a pre-operative suspicion of intra-ductal stones, to determine if any biliary complications had subsequently developed. A group of patients who had no pre-operative suspicion of intra-ductal stones, but routinely underwent intraoperative cholangiogram (IOC) at time of cholecystectomy, served as the control group.

METHODS

A telephone questionnaire was completed by each patient's family practitioner in 59 of 79 (75%) patients who underwent laparoscopic cholecystectomy. In the remaining 20 patients additional information was obtained from hospital records and from the central services agency (CSA). These patients had no pre-operative suspicion of bile duct stones and therefore did not undergo an IOC or ERCP. The control group (73 patients) had no pre-operative suspicion of bile duct stones but had a routine IOC performed to define the biliary anatomy.

RESULTS

59 patients were followed up for an average of 57 months (range 30-78 months) after laparoscopic cholecystectomy. None of these patients developed pancreatitis, jaundice, deranged liver function tests (LFT's), or required ERCP or other biliary intervention. In the additional 20 patients where no information was available from the family practitioner, 11 patients had follow up appointments with no documentation of biliary complications or abnormal LFT's. 19 of 20 patients were traceable through the CSA and were all alive. Only 1 patient was untraceable and therefore unknown if biliary complications had developed. In the control group, 4 of 73 (6%) patients had intraductal stones detected and extracted. Thus the prevalence of asymptomatic bile duct stones during the time of cholecystectomy in our population was 6%.

CONCLUSIONS

Asymptomatic bile duct stones discovered at the time of cholecystectomy do not appear to cause any biliary complications over a 5-year follow up. Incidental bile duct stones found in patients undergoing laparoscopic cholecystectomy may not need to be removed.

Complete genome sequence and lytic phase transcription profile of a Coccolithovirus

The genus Coccolithovirus is a recently discovered group of viruses that infect the globally important marine calcifying microalga Emiliania huxleyi. Among the 472 predicted genes of the 407,339-base pair genome are a variety of unexpected genes, most notably those involved in biosynthesis of ceramide, a sphingolipid known to induce apoptosis. Uniquely for algal viruses, it also contains six RNA polymerase subunits and a novel promoter, suggesting this virus encodes its own transcription machinery. Microarray transcriptomic analysis reveals that 65% of the predicted virus-encoded genes are expressed during lytic infection of E. huxleyi.

Cooperativity in the binding of the cationic biocide polyhexamethylene biguanide to nucleic acids

The interaction between the broad-spectrum antimicrobial agent, polyhexamethylene biguanide (PHMB), and various nucleic acids was investigated. Titration of either single- or double-stranded 100-bp DNA, or mixed-molecular weight marker DNA, or tRNA with PHMB caused precipitation of a complex between nucleic acid and PHMB in which the nucleotide/biguanide ratio was always close to unity. Binding of PHMB was highly cooperative, with apparent Hill coefficients 10.3-14.6. When a fluorescent derivative of PHMB was titrated with increasing amounts of nucleic acid, all four forms of nucleic acid caused strong polarisation of fluorescence, demonstrating the association with PHMB. The intensity and broad-spectrum binding of PHMB to all forms of nucleic acid has significant implications for the mechanism of action of this biocide.

The Effect of Deinsuring Chlorpropamide on the Prescribing of Oral Antihyperglycemics for Nova Scotia Seniors’ Pharmacare Beneficiaries

On behalf of the Nova Scotia Seniors' Pharmacare Program, the Drug Evaluation Alliance of Nova Scotia developed a multicomponent intervention plan to facilitate the removal of chlorpropamide as an insured benefit. Chlorpropamide has caused serious hypoglycemia in seniors to a greater extent than some other agents. Pharmacy administrative claims were used to compute monthly use rates for insulin and each oral antihyperglycemic drug from January 1, 2000-December 30, 2002, in an intervention cohort (patients receiving chlorpropamide) and a control cohort (patients receiving an antihyperglycemic agent other than chlorpropamide). Initially, 630 patients were receiving chlorpropamide therapy. By the time chlorpropamide was deinsured, only 10% of the treatment cohort continued receiving chlorpropamide; shortly after deinsurance, no beneficiaries continued receiving the drug. The antihyperglycemics with the greatest increase in prescription were glyburide and gliclazide. The deinsuring of chlorpropamide and the educational strategies that accompanied it resulted in the selection of more appropriate antihyperglycemics for Nova Scotia seniors.

Force spectroscopy of the double-tethered concanavalin-A mannose bond

We present the measurement of the force required to rupture a single protein-sugar bond using a methodology that provides selective discrimination between specific and nonspecific binding events and helps verify the presence of a single functional molecule on the atomic force microscopy tip. In particular, the interaction force between a polymer-tethered concanavalin-A protein (ConA) and a similarly tethered mannose carbohydrate was measured as 47 +/- 9 pN at a bond loading rate of approximately 10 nN/s. Computer simulations of the polymer molecular configurations were used to determine the angles that the polymers could sweep out during binding and, in conjunction with mass spectrometry, used to separate the angular effects from the effects due to a distribution of tether lengths. We find that when using commercially available polymer tethers that vary in length from 19 to 29 nm, the angular effects are relatively small and the rupture distributions are dominated by the 10-nm width of the tether length distribution. In all, we show that tethering both a protein and its ligand allows for the determination of the single-molecule bond rupture force with high sensitivity and includes some validation for the presence of a single-tethered functional molecule on the atomic force microscopy tip.

Voriconazole, a novel wide-spectrum triazole: oral pharmacokinetics and safety

AIMS

Voriconazole is a potent new triazole with broad-spectrum antifungal activity against clinically significant and emerging pathogens. The present study evaluated the safety, toleration, and pharmacokinetics of oral voriconazole after single and multiple dosing.

METHODS

Sixty-four healthy subjects were randomized to receive treatment and 56 completed the study. Groups of eight subjects each received voriconazole doses of 2 mg kg-1 twice daily, 4 mg kg-1 once daily, 2 mg kg-1 three times daily, or 3 mg kg-1 twice daily. Eleven subjects received 1.5 mg kg-1 three times daily, and 21 subjects were administered placebo.

RESULTS

Voriconazole exhibited nonlinear (dose- and time-dependent) pharmacokinetics. This deviation from linear pharmacokinetics was confirmed by linearity ratios of > 1 and decreasing kel values on multiple dosing, with a consequent increase in the terminal phase t1/2. There was also notable intersubject variability in Cmax and AUCtau. The absorption of voriconazole was rapid (mean tmax= 0.9-1.7 h) after single and multiple dosing and the decline in plasma concentration-time curves after tmax was generally biphasic. By day 12, the Cmax, AUCtau, tmax, and t1/2 values for the 3 mg kg-1 twice-daily group were 2356 ng ml-1, 11 170 ng.h ml-1, 1.1 h, and 6.4 h, respectively. The observed accumulation of voriconazole after multiple dosing was greater than predicted from single-dose data. Accumulation ratios for Cmax and AUCtau, which were 1.97 and 3.55, respectively, for the group given voriconazole 3 mg kg-1 twice daily, varied between treatment groups and appeared to be influenced by total daily dose and the frequency and duration of dosing. Visual inspection of Cmin values together with statistical analyses of Cmax and AUCtau values suggest that steady-state levels were achieved by the fifth to sixth day of multiple dosing. Plasma concentrations of voriconazole were well above the minimum inhibitory concentrations (MICs) for Aspergillus spp., Candida spp., and for most emerging fungal pathogens (Cmin > 0.8 micro g ml-1). Voriconazole was well tolerated: most treatment-related adverse events (abnormal vision, headache, dizziness) were mild and resolved within an hour of dosing.

CONCLUSIONS

The oral dosing regimen selected for subsequent Phase II/III clinical trials on the basis of these results was 200 mg twice daily, equivalent to 3 mg kg-1 twice daily.