Publications

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) is characterized by variations (sometimes extreme) by country and geographic region. The conventional association of MRSA with healthcare settings has been upset by the emergence of community-associated MRSA infections in many areas. With this surge in MRSA comes a renewed interest in alternative agents to vancomycin for treatment of MRSA infections, including older drugs, such as clindamycin, doxycycline and trimethoprim- sulfamethoxazole. Newer agents, such as linezolid and daptomycin, are aiming to improve on the poor cure rates found with vancomycin in serious MRSA infections, but definitive studies showing superiority of these drugs are not yet available. Finally, the drug-development pipeline contains a number of agents for the treatment of MRSA infections, including enhanced glycopeptides (dalbavancin, oritavancin and telavancin) and anti-MRSA cephalosporins (ceftobiprole). As MRSA becomes the 'new normal' in many areas, clinicians will have to sort out the proper role of a dozen or more anti-MRSA drugs.

BACKGROUND

There is growing evidence for the role of oxidative damage in chronic diseases. Although ozone (O3) is an oxidant pollutant to which many people are exposed, few studies have examined whether O3 induces oxidative stress in humans.

OBJECTIVES

This study was designed to assess the effect of short-and long-term O(3) exposures on biomarkers of oxidative stress in healthy individuals.

METHODS

Biomarkers of lipid peroxidation, 8-isoprostane (8-iso-PGF), and antioxidant capacity ferric reducing ability of plasma (FRAP) were analyzed in two groups of healthy college students with broad ranges of ambient O3 exposure during their lifetimes and previous summer recess either in Los Angeles (LA, n = 59) or the San Francisco Bay Area (SF, n = 61).

RESULTS

Estimated 2-week, 1-month, and lifetime O3 exposures were significantly correlated with elevated 8-iso-PGF. Elevated summertime exposures resulted in the LA group having higher levels of 8-iso-PGF than the SF group (p = 0.02). Within each location, males and females had similar 8-iso-PGF. No regional difference in FRAP was observed, with significantly higher FRAP in males in both groups (SF: p = 0.002; LA: p = 0.004). An exposure chamber substudy (n = 15) also showed a significant increase in 8-iso-PGF as well as an inhibition of FRAP immediately after a 4-hr exposure to 200 ppb O3, with near normalization by 18 hr in both biomarkers.

CONCLUSIONS

Long-term exposure to O3 is associated with elevated 8-iso-PGF, which suggests that 8-iso-PGF is a good biomarker of oxidative damage related to air pollution.

OBJECTIVE

To assess the safety and tolerability of atacicept in patients with systemic lupus erythematosus (SLE) and the biologic effect of atacicept on B lymphocyte and immunoglobulin levels. Atacicept is a TACI-Ig fusion protein that inhibits B cell stimulation by binding to B lymphocyte stimulator and a proliferation-inducing ligand.

METHODS

This phase Ib, double-blind, placebo-controlled, dose-escalating trial comprised 6 cohorts of patients treated with atacicept or placebo in a 3:1 ratio of active drug to placebo (n = 8 per group; n = 7 in cohort 5). Cohorts 1-4 received a single subcutaneous dose of placebo or either 0.3 mg/kg, 1 mg/kg, 3 mg/kg, or 9 mg/kg of atacicept. Cohorts 5 and 6 received weekly doses of placebo or either 1 mg/kg or 3 mg/kg of atacicept for 4 weeks. Patients were followed up for 6 weeks (cohorts 1-4) or 9 weeks (cohorts 5 and 6). Patients with mild-to-moderate SLE were enrolled.

RESULTS

Biologic activity of atacicept was demonstrated by dose-dependent reductions in immunoglobulin levels and in mature and total B cell numbers. This effect was most pronounced in the repeated-dose cohorts and was sustained throughout the followup period. There were no changes in the numbers of T cells, natural killer cells, or monocytes. Mild injection-site reactions occurred more frequently among the atacicept group than the placebo group. There were no differences in the frequency or type of adverse events and no severe or serious adverse events in patients treated with atacicept.

CONCLUSION

Atacicept administered subcutaneously was well tolerated and demonstrated biologic activity consistent with the proposed mechanism of action.

BACKGROUND

The relationship between body mass index (BMI), weight loss, and mortality in older adults is not entirely clear. The purpose of this article is to evaluate the associations between BMI, weight loss (either intentional or unintentional), and 3-year mortality in a cohort of older adults participating in the University of Alabama at Birmingham (UAB) Study of Aging.

METHODS

This article reports on 983 community-dwelling older adults who were enrolled in the UAB Study of Aging, a longitudinal observational study of mobility among older African American and white adults.

RESULTS

In both raw and adjusted Cox proportional hazards models, unintentional weight loss and underweight BMI were associated with elevated 3-year mortality rates. There was no association with being overweight or obese on mortality, nor was there an association with intentional weight loss and mortality.

CONCLUSIONS

Our study suggests that undernutrition, as measured by low BMI and unintentional weight loss, is a greater mortality threat to older adults than is obesity or intentional weight loss.

The second messenger cAMP acts via protein kinase A (PKA) to induce apoptosis by mechanisms that are poorly understood. Here, we assessed a role for mitochondria and analyzed gene expression in cAMP/PKA-promoted apoptosis by comparing wild-type (WT) S49 lymphoma cells and the S49 variant, D(-) (cAMP-deathless), which lacks cAMP-promoted apoptosis but has wild-type levels of PKA activity and cAMP-promoted G(1) growth arrest. Treatment of WT, but not D(-), S49 cells with 8-CPT-cAMP (8-(4-chlorophenylthio)-adenosine-3':5'-cyclic monophosphate) for 24 h induced loss of mitochondrial membrane potential, mitochondrial release of cytochrome c and SMAC, and increase in caspase-3 activity. Gene expression analysis (using Affymetrix 430 2.0 arrays) revealed that WT and D(-) cells incubated with 8-CPT-cAMP have similar, but non-identical, extents of cAMP-regulated gene expression at 2 h (approximately 800 transcripts) and 6 h (approximately 1000 transcripts) (|Fold| > 2, p < 0.06); by contrast, at 24 h, approximately 2500 and approximately 1100 transcripts were changed in WT and D(-) cells, respectively. Using an approach that combined regression analysis, clustering, and functional annotation to identify transcripts that showed differential expression between WT and D(-) cells, we found differences in cAMP-mediated regulation of mRNAs involved in transcriptional repression, apoptosis, the cell cycle, RNA splicing, Golgi, and lysosomes. The two cell lines differed in cAMP-response element-binding protein (CREB) phosphorylation and expression of the transcriptional inhibitor ICER (inducible cAMP early repressor) and in cAMP-regulated expression of genes in the inhibitor of apoptosis (IAP) and Bcl families. The findings indicate that cAMP/PKA-promoted apoptosis of lymphoid cells occurs via mitochondrial-mediated events and imply that such apoptosis involves gene networks in multiple biochemical pathways.

G protein-coupled receptors (GPCRs) coupled to activation of Gs, such as the PTH1 receptor (PTH1R), have long been known to regulate skeletal function and homeostasis. However, the role of GPCRs coupled to other G proteins such as Gi is not well established. We used the tet-off system to regulate the expression of an activated Gi-coupled GPCR (Ro1) in osteoblasts in vivo. Skeletal phenotypes were assessed in mice expressing Ro1 from conception, from late stages of embryogenesis, and after weaning. Long bones were assessed histologically and by microcomputed tomography. Expression of Ro1 from conception resulted in neonatal lethality that was associated with reduced bone mineralization. Expression of Ro1 starting at late embryogenesis resulted in a severe trabecular bone deficit at 12 wk of age (>51% reduction in trabecular bone volume fraction in the proximal tibia compared with sex-matched control littermates; n = 11; P < 0.01). Ro1 expression for 8 wk beginning at 4 wk of age resulted in a more than 20% reduction in trabecular bone volume fraction compared with sex-matched control littermates (n = 16; P < 0.01). Bone histomorphometry revealed that Ro1 expression is associated with reduced rates of bone formation and mineral apposition without a significant change in osteoblast or osteoclast surface. Our results indicate that signaling by a Gi-coupled GPCR in osteoblasts leads to osteopenia resulting from a reduction in trabecular bone formation. The severity of the phenotype is related to the timing and duration of Ro1 expression during growth and development. The skeletal phenotype in Ro1 mice bears some similarity to that produced by knockout of Gs-alpha expression in osteoblasts and thus may be due at least in part to Gi-mediated inhibition of adenylyl cyclase.