Megan M. McLaughlin

The ARO4 gene of Candida albicans encodes a tyrosine-sensitive DAHP synthase: evolution, functional conservation and phenotype of Aro3p-, Aro4p-deficient mutants

The enzyme 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP) synthase catalyses the first step in aromatic amino acid biosynthesis in prokaryotes, plants and fungi. Cells of Saccharomyces cerevisiae contain two catalytically redundant DAHP synthases, encoded by the genes ARO3 and ARO4, whose activities are feedback-inhibited by phenylalanine and tyrosine, respectively. ARO3/4 gene transcription is controlled by GCN4. The authors previously cloned an ARO3 gene orthologue from Candida albicans and found that: (1) it can complement an aro3 aro4 double mutation in S. cerevisiae, an effect inhibited by excess phenylalanine, and (2) a homozygous aro3-deletion mutant of C. albicans is phenotypically Aro(+), suggesting the existence of another isozyme(s). They now report the identification and functional characterization of the C. albicans orthologue of S. cerevisiae Aro4p. The two Aro4p enzymes share 68% amino acid identity. Phylogenetic analysis places the fungal DAHP synthases in a cluster separate from prokaryotic orthologues and suggests that ARO3 and ARO4 arose from a single gene via a gene duplication event early in fungal evolution. C. albicans ARO4 mRNA is elevated upon amino acid starvation, consistent with the presence of three putative Gcn4p-responsive elements (GCREs) in the gene promoter sequence. C. albicans ARO4 complements an aro3 aro4 double mutation in S. cerevisiae, an effect inhibited by excess tyrosine. The authors engineered Deltaaro3/Deltaaro3 Deltaaro4/MET3p::ARO4 cells of C. albicans (with one wild-type copy of ARO4 placed under control of the repressible MET3 promoter) and found that they fail to grow in the absence of aromatic amino acids when ARO4 expression is repressed, and that this growth defect can be partially rescued by aromatic amino acids and certain aromatic amino acid pathway intermediates. It is concluded that, like S. cerevisiae, C. albicans contains two DAHP synthases required for the first step in the aromatic amino acid biosynthetic pathway.

Initial exploration of oral pazopanib in healthy participants and patients with age-related macular degeneration.

IMPORTANCEnNeovascular age-related macular degeneration (AMD) is managed with intravitreal anti-vascular endothelial growth factor therapy; however, the burden of care is high and alternate approaches could be beneficial. OBJECTIVE To identify an acceptable dose of oral pazopanib for investigation in AMD.nnnDESIGN, SETTING, AND PARTICIPANTSnFourteen-day, placebo-controlled, dose-rising study in 72 healthy participants and 28-day phase 2a open-label study in 15 patients with subfoveal choroidal neovascularization secondary to AMD at a clinical unit for healthy participants and outpatient for patients with AMD.nnnINTERVENTIONnOral pazopanib tablets, 5 to 30 mg daily (healthy participants) and 15 mg daily (patients with AMD).nnnMAIN OUTCOMES AND MEASURESnSafety, pharmacokinetics, best-corrected visual acuity, central retinal lesion thickness, and central retinal thickness at day 29.nnnRESULTSnOral pazopanib up to 30 mg daily in healthy participants and 15 mg daily in patients with AMD was well tolerated. Six of 15 patients received rescue therapy before day 29; all had the CFH Y402H CC high-risk genotype for AMD. Nine patients completed the study without rescue with improvements from baseline in best-corrected visual acuity (8 Early Treatment Diabetic Retinopathy Study letters), central retinal lesion thickness (-50.94 µm), and central retinal thickness (-50.28 µm). There was a trend for association between the CFH Y402H T allele (low risk for AMD, n = 6) and improvement.nnnCONCLUSIONS AND RELEVANCEnOral pazopanib (15 mg daily) was well tolerated and resulted in improvements in mean best-corrected visual acuity, central retinal lesion thickness, and central retinal thickness at day 29 in a per-protocol, nonrescued AMD population (n = 9). It is postulated that CFH Y402H genotype may help predict which patients respond to pazopanib. The size and length limitations of this study warrant further investigation to determine if oral pazopanib may be an appropriate treatment for a subset of neovascular patients with AMD or as an adjunct to standard of care.nnnTRIAL REGISTRATIONnclinicaltrials.gov Identifier: NCT01051700 and NCT01154062.

Darapladib, a lipoprotein-associated phospholipase A2 inhibitor, in diabetic macular edema: a 3-month placebo-controlled study.

PURPOSEnTo investigate the potential of lipoprotein-associated phospholipase A2 inhibition as a novel mechanism to reduce edema and improve vision in center-involved diabetic macular edema (DME).nnnDESIGNnProspective, multicenter, randomized, double-masked, placebo-controlled phase IIa study.nnnPARTICIPANTSnFifty-four center-involved DME patients randomized 2:1 to receive darapladib (n = 36) or placebo (n = 18).nnnMETHODSnDarapladib 160 mg or placebo monotherapy was administered orally once daily for 3 months, and patients were followed up monthly for 4 months.nnnMAIN OUTCOME MEASURESnMean change from baseline in best-corrected visual acuity (BCVA) and the center subfield and center point of the study eye at month 3 as determined by spectral-domain optical coherence tomography.nnnRESULTSnFive patients in the study received intravitreal anti-vascular endothelial growth factor rescue therapy before the day 90 assessment, 2 of 36 (6%) in the darapladib arm and 3 of 18 (17%) in the placebo arm. Administration of 160 mg darapladib for 3 months resulted in statistically significant mean improvements, from baseline to month 3, in BCVA of 4.1 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (95% confidence interval [CI], 2.3-5.8) and of 57 μm in central subfield thickness (95% CI, -84 to -30) in the study eyes. An increase in BCVA of 1.7 ETDRS letters (95% CI, -1.0 to 4.4) and a decrease in center subfield thickness of 34 μm (95% CI, -75 to 6.8) for the placebo group were not significant. No ocular severe adverse events (SAEs) or SAEs considered related to darapladib were reported. One SAE of myocardial infarction, not considered related to darapladib, was reported, and 1 SAE of severe diarrhea was reported in a placebo patient, subsequently withdrawn from the study. Study eye ocular adverse events (AEs) and nonocular AEs were similar between treatment groups.nnnCONCLUSIONSnOnce-daily oral darapladib administered for 3 months demonstrated modest improvements in vision and macular edema that warrant additional investigation of this novel lipoprotein-associated phospholipase A2 inhibitory mechanism for the treatment of DME.

Pazopanib eye drops: a randomised trial in neovascular age-related macular degeneration

Aims To evaluate pazopanib eye drops in patients with subfoveal choroidal neovascularisation secondary to age-related macular degeneration. Methods 70 patients with minimally classic or occult subfoveal choroidal neovascularisation were randomly assigned to 5u2005mg/mL TID, 2u2005mg/mL TID, and 5u2005mg/mL QD pazopanib eye drops for 28u2005days in a multicentre, double-masked trial with an optional safety extension for up to 5 additional months. The primary outcomes were central retinal thickness (CRT) and best-corrected visual acuity (BCVA) at Day 29. Results No significant decrease from baseline in CRT was observed overall; however, an exploratory analysis showed improvement in CRT (mean decrease of 89u2005μm) in patients with the CFH TT genotype who received 5u2005mg/mL TID (p=0.01, n=5). Mean increases in BCVA were observed in the 5u2005mg/mL TID overall (4.32 letters (p=0.002, n=26)) and in those that with CFH Y402H TT (6.96 letters (p=0.02, n=5)) and CT (4.09 letters (p=0.05, n=9)) genotypes. No safety signals that precluded continued investigation were detected. Conclusions 5u2005mg/mL pazopanib eye drops resulted in mean improvement in BCVA at Day 29 and improvements in vision. However, improvement in macular oedema for age-related macular degeneration was found only in the subset of subjects with the CFH Y402H TT genotype, warranting further investigation.

A bicistronic expression system for bacterial production of authentic human interleukin-18

Interleukin-18 (IL-18) is activated and released from immune effector cells to stimulate acquired and innate immune responses involving T and natural killer (NK) cells. The release of IL-18 from mammalian cells is linked to its proteolytic activation by caspases including interleukin 1 converting enzyme (ICE). The absence of a signal peptide sequence and the requirement for coupled activation and cellular release have presented challenges for the large-scale recombinant production of IL-18. In this study, we have explored methods for the direct production of authentic human IL-18 toward the development of a large-scale production system. Expression of mature IL-18 directly in Escherichia coli with a methionine initiating codon leads to the production of MetIL-18 that is dramatically less potent in bioassays than IL-18 produced as a pro-peptide and activated in vitro. To produce an authentic IL-18, we have devised a bicistronic expression system for the coupled transcription and translation of ProIL-18 with caspase-1 (ICE) or caspase-4 (ICE-rel II, TX, ICH-2). Mature IL-18 with an authentic N-terminus was produced and has a biological activity and potency comparable to that of in vitro processed mature IL-18. Optimization of this system for the maximal production yields can be accomplished by modulating the temperature, to affect the rate of caspase activation and to favor the accumulation of ProIL-18, prior to its proteolytic processing by activated caspase. The effect of temperature is particularly profound for the caspase-4 co-expression process, enabling optimized production levels of over 150 mg/L in shake flasks at 25 degrees C. An alternative bicistronic expression design utilizing a precise ubiquitin IL-18 fusion, processed by co-expressed ubiquitinase, was also successfully used to generate fully active IL-18, thereby demonstrating that the pro-sequence of IL-18 is not required for recombinant IL-18 production.

Superiority of dutasteride 0.5 mg and tamsulosin 0.2 mg for the treatment of moderate-to-severe benign prostatic hyperplasia in Asian men

To assess the effectiveness and safety of dutasteride 0.5 mg + tamsulosin 0.2 mg combination compared with tamsulosin 0.2 mg in Asian men with moderate‐to‐severe benign prostatic hyperplasia.

Lp-PLA2 activity is associated with increased risk of diabetic retinopathy: a longitudinal disease progression study

Aims/hypothesisThe aim of the study was to examine the association between lipoprotein-associated phospholipase A2 (Lp-PLA2) activity levels and incident diabetic retinopathy and change in retinopathy grade.MethodsThis was a cohort study of diabetic participants with serum collected at baseline and routinely collected diabetic retinal screening data. Participants with type 2 diabetes from the GoDARTS (Genetics of Diabetes Audit and Research in Tayside Scotland) cohort were used. This cohort is composed of individuals of white Scottish ancestry from the Tayside region of Scotland. Survival analysis accounting for informative censoring by modelling death as a competing risk was performed for the development of incident diabetic retinopathy from a disease-free state in a 3xa0year follow-up period (nu2009=u20091364) by stratified Lp-PLA2 activity levels (in quartiles). The same analysis was performed for transitions to more severe grades.ResultsThe hazard of developing incident diabetic retinopathy was 2.08 times higher (95% CI 1.64, 2.63) for the highest quartile of Lp-PLA2 activity compared with the lowest. Higher Lp-PLA2 activity levels were associated with a significantly increased risk for transitions to all grades. The hazards of developing observable (or more severe) and referable (or more severe) retinopathy were 2.82 (95% CI 1.71, 4.65) and 1.87 (95% CI 1.26, 2.77) times higher for the highest quartile of Lp-PLA2 activity compared with the lowest, respectively.Conclusions/interpretationHigher Lp-PLA2 levels are associated with increased risk of death and the development of incident diabetic retinopathy, as well as transitions to more severe grades of diabetic retinopathy. These associations are independent of calculated LDL-cholesterol and other traditional risk factors. Further, this biomarker study shows that the association is temporally sensitive to the proximity of the event to measurement of Lp-PLA2.

A systematic review and meta-analysis to compare the efficacy of acyclovir 3% ophthalmic ointment to idoxuridine in curing herpetic keratitis by Day 7 of treatment

BackgroundThis objective of the review and analysis is to demonstrate that acyclovir (ACV) 3% ophthalmic ointment is superior to idoxuridine (IDU) in treating herpetic keratitis (HK) presenting as dendritic and geographic ulcer sub-types.MethodsData sources: Publications in human subjects were identified by searching the Ovid MEDLINE database through April 2011, combining medical subject headings (MESH) “Keratitis, Herpetic/” AND “Acyclovir/” limiting by the key words “topical” OR “ointment” and also restricted to MESH “Administration, Topical/” OR “Ointments/”. The results were cross checked with the references used in the Cochrane Database Syst Rev. 1:1–134, 2009 and GlaxoSmithKline clinical documents related to acyclovir.Study selection: Randomized, double-masked studies in subjects diagnosed with HK with head to head comparator arms of ACV ophthalmic ointment and topical IDU that had actual or calculable healing rates at Day seven.Data extraction: Data independently extracted from identified articles by two authors of this manuscript.Data synthesis: Data from seven randomized, controlled trials (RCT) evaluating 432 subjects that met inclusion criteria (214 were treated with ACV and 218 were treated with IDU) and had Day seven healing rates calculable. All sub-classified lesions were identified as either dendritic ulcers (nu2009=u2009185) or geographic ulcers (nu2009=u200935). The Cochran-Mantel-Haenszel (CMH) method in Biometrics 10:417-51, 1954 and JNCI 22:719-48, 1959, controlling for study, was performed as the primary analysis using SAS v9.Homogeneity was assessed using Breslow-Day-Tarone (BDT) test in IARC 1:1-32, 1980 and Biometrika 72:91-5, 1985. The analysis was performed with outliers removed to assess their impact.ResultsACV showed statistically significant greater odds of healing HK at Day seven in all subjects (Odds Ratio 3.95, 95% CI2.60, 6.00, p <0.0001), in dendritic ulcers (Odds Ratio 4.22, 95% CI: 2.14, 8.32; pu2009<u20090.0001) and geographic ulcers (Odds Ratio 5.31, 95% CI: 1.09, 25.93; p =0.0244).ConclusionACV 3% ophthalmic ointment is a valuable intervention for dendritic and geographic corneal ulcers. ACV and IDU were generally well tolerated in the studies reviewed.