Constructing tailored isoprenoid products by structure-guided modification of geranylgeranyl reductase.

The archaeal enzyme geranylgeranyl reductase (GGR) catalyzes hydrogenation of carbon-carbon double bonds to produce the saturated alkyl chains of the organism's unusual isoprenoid-derived cell membrane. Enzymatic reduction of isoprenoid double bonds is of considerable interest both to natural products researchers and to synthetic biologists interested in the microbial production of isoprenoid drug or biofuel molecules. Here we present crystal structures of GGR from Sulfolobus acidocaldarius, including the structure of GGR bound to geranylgeranyl pyrophosphate (GGPP). The structures are presented alongside activity data that depict the sequential reduction of GGPP to H6GGPP via the intermediates H2GGPP and H4GGPP. We then modified the enzyme to generate sequence variants that display increased rates of H6GGPP production or are able to halt the extent of reduction at H2GGPP and H4GGPP. Crystal structures of these variants not only reveal the structural bases for their altered activities; they also shed light onto the catalytic mechanism employed.

Dexamethasone intravitreal implant for treatment of diabetic macular edema in vitrectomized patients.

PURPOSE: To evaluate the safety and efficacy of Ozurdex (dexamethasone intravitreal implant) 0.7 mg in the treatment of diabetic macular edema in vitrectomized eyes. METHODS: This was a prospective, multicenter, open-label, 26-week study. Fifty-five patients with treatment-resistant diabetic macular edema and a history of previous pars plana vitrectomy in the study eye received a single intravitreal injection of 0.7-mg dexamethasone intravitreal implant. The primary efficacy outcome measure was the change in central retinal thickness from baseline to Week 26 measured by optical coherence tomography. RESULTS: The mean age of patients was 62 years. The mean duration of diabetic macular edema was 43 months. The mean (95% confidence interval) change from baseline central retinal thickness (403 µm) was -156 µm (-190, -122 µm) at Week 8 (P < 0.001) and -39 µm (-65, -13 µm) at Week 26 (P = 0.004). The mean (95% CI) increase in best-corrected visual acuity from baseline (54.5 letters) was 6.0 letters (3.9, 8.1 letters) at Week 8 (P < 0.001) and 3.0 letters (0.1, 6.0 letters) at Week 26 (P = 0.046). At Week 8, 30.4% of patients had gained ≥10 letters in best-corrected visual acuity. Conjunctival hemorrhage, conjunctival hyperemia, eye pain, and increased intraocular pressure were the most common adverse events. CONCLUSION: Treatment with dexamethasone intravitreal implant led to statistically and clinically significant improvements in both vision and vascular leakage from diabetic macular edema in difficult-to-treat vitrectomized eyes and had an acceptable safety profile.

Active comparator trial of teriparatide vs alendronate for treating glucocorticoid-induced osteoporosis: results from the Hispanic and non-Hispanic cohorts.

Glucocorticoid use is a leading cause of secondary osteoporosis. This post hoc analysis compared teriparatide vs alendronate on bone mineral density (BMD) in Hispanic and non-Hispanic patients with glucocorticoid-induced osteoporosis. The 18-mo results from all patients (N=428) in a double-blind trial of teriparatide (20 microg/d) and alendronate (10 mg/d) who had taken glucocorticoids for >or=3 mo were reported (Saag et al. N Engl J Med 2007). The present study analyzed results from the Hispanic (n=61) and non-Hispanic (n=367) cohorts. The BMD was measured by dual-energy X-ray absorptiometry (DXA). In the Hispanic cohort at 18 mo, there were significantly greater increases from baseline in the teriparatide vs alendronate group in lumbar spine BMD (9.8%+/-1.7% vs 4.2%+/-1.4%; p<0.001; mean+/-SE) and total hip BMD (5.9%+/-1.6% vs 1.3%+/-1.3%, p<0.001), with no significant difference between groups at the femoral neck (4.3%+/-2.2% vs 2.0%+/-1.8%, p=0.228). Within each treatment group, the BMD responses were not significantly different in the Hispanic vs non-Hispanic cohort. The number of patients reporting >or=1 adverse event was not significantly different between treatments in either cohort, with more patients reporting nausea in the teriparatide group. In summary, teriparatide was more efficacious than alendronate in increasing BMD in Hispanic and non-Hispanic patients with glucocorticoid-induced osteoporosis. Both treatments were generally well tolerated.