Brain parenchymal TNF-α and IL-1ß induction in experimental pneumococcal meningitis.

Triggers of brain inflammation in pneumococcal meningitis are unknown. TNF-α and IL-1ß were upregulated (real time PCR and in situ hybridization) in neurons and astrocytes time-dependently and maximally in the hippocampus during murine pneumococcal meningitis. Upregulation of TNF-α and IL-1ß mRNA in the brain parenchyma was independent of cerebrospinal fluid leukocytosis, pneumococcal pneumolysin and H2O2, but it was potently induced by pneumococcal cell wall (PCW) fragments. Brain TNF-α mRNA was downregulated by a matrix metalloproteinases inhibitor. PCW fragments were located in the brain parenchyma. In conclusion, PCW fragments and matrix metalloproteinases trigger cytokine induction in the brain parenchyma during pneumococcal meningitis.

Is serum phosphorus control related to parathyroid hormone control in dialysis patients with secondary hyperparathyroidism?

BACKGROUND: Elevated serum phosphorus (P) levels have been linked to increased morbidity and mortality in dialysis patients with secondary hyperparathyroidism (SHPT) but may be difficult to control if parathyroid hormone (PTH) is persistently elevated. We conducted a post hoc analysis of data from an earlier interventional study (OPTIMA) to explore the relationship between PTH control and serum P. METHODS: The OPTIMA study randomized dialysis patients with intact PTH (iPTH) 300-799 pg/mL to receive conventional care alone (vitamin D and/or phosphate binders [PB]; n=184) or a cinacalcet-based regimen (n=368). For patients randomized to conventional care, investigators were allowed flexibility in using a non-cinacalcet regimen (with no specific criteria for vitamin D analogue dosage) to attain KDOQI™ targets for iPTH, P, Ca and Ca x P. For those assigned to the cinacalcet-based regimen, dosages of cinacalcet, vitamin D sterols, and PB were optimized over the first 16 weeks of the study, using a predefined treatment algorithm. The present analysis examined achievement of serum P targets (≤ 4.5 and ≤ 5.5 mg/dL) in relation to achievement of iPTH ≤ 300 pg/mL during the efficacy assessment phase (EAP; weeks 17-23). RESULTS: Patients who achieved iPTH ≤ 300 pg/mL (or a reduction of ≥ 30% from baseline) were more likely to achieve serum P targets than those who did not, regardless of treatment group. Of those who did achieve iPTH ≤ 300 pg/mL, 43% achieved P ≤ 4.5 mg/dL and 70% achieved P ≤ 5.5 mg/dL, versus 21% and 46% of those who did not achieve iPTH ≤ 300 pg/mL. Doses of PB tended to be higher in patients not achieving serum P targets. Patients receiving cinacalcet were more likely to achieve iPTH ≤ 300 pg/mL than those receiving conventional care (73% vs 23% of patients). Logistic regression analysis identified lower baseline P, no PB use at baseline and cinacalcet treatment to be predictors of achieving P ≤ 4.5 mg/dL during EAP in patients above this threshold at baseline. CONCLUSIONS: This post hoc analysis found that control of serum P in dialysis patients was better when serum PTH levels were lowered effectively, regardless of treatment received. TRIAL REGISTRATION: Clinicaltrials.gov identifier NCT00110890.

Bacterial pore-forming cytolysins induce neuronal damage in a rat model of neonatal meningitis.

BACKGROUND: Group B Streptococcus (GBS) and Streptococcus pneumoniae (SP) are leading causes of bacterial meningitis in neonates and children. Each pathogen produces a pore-forming cytolytic toxin, ß-hemolysin/cytolysin (ß-h/c) by GBS and pneumolysin by SP. The aim of this study was to understand the role of these pore-forming cytotoxins, in particular of the GBS ß-h/c, as potential neurotoxins in experimental neonatal meningitis. METHODS: Meningitis was induced in 7- and 11-day-old rats by intracisternal injection of wild type (WT) GBS or SP and compared with isogenic ß-h/c- or pneumolysin-deficient mutants, or a double mutant of SP deficient in pneumolysin and hydrogen peroxide production. RESULTS: GBS ß-h/c and SP pneumolysin contributed to neuronal damage, worsened clinical outcome and weight loss, but had no influence on the early kinetics of leukocyte influx and bacterial growth in the cerebrospinal fluid. In vitro, ß-h/c-induced neuronal apoptosis occurred independently of caspase-activation and was not preventable by the broad spectrum caspase-inhibitor z-VAD-fmk. CONCLUSIONS: These data suggest that both cytolytic toxins, the GBS ß-h/c and SP pneumolysin, contribute to neuronal damage in meningitis and extend the concept of a key role for bacterial pore-forming cytolysins in the pathogenesis and sequelae of neonatal meningitis.

Ecto-5'-nucleotidase-positive cells in the choroid and ciliary body of the rat eye.

Adenosine is known to exert multiple functions within the eye. The aim of this report was to find out if adenosine can be produced locally in the choroid and ciliary body. Therefore, I investigated the distribution of ecto-5'-nucleotidase (5'-NT), the key enzyme for the production of extracellular adenosine. This report provides evidence that 5'-NT is expressed in the choroid and in the ciliary body (and its processes) of the rat eye, predominantly in endothelial cells. These locations of 5'-NT indicate strategically important production sites of adenosine regulating choroid and ciliary body functions (e.g., blood flow, aqueous fluid production, and immune response).

Impact of vitamin D dose on biochemical parameters in patients with secondary hyperparathyroidism receiving cinacalcet.

BACKGROUND/AIMS: The calcimimetic cinacalcet (Mimpara/Sensipar) simultaneously lowers parathyroid hormone (PTH), phosphorus (P) and calcium (Ca) levels in patients with secondary hyperparathyroidism. The OPTIMA study demonstrated that cinacalcet and adjusted doses of vitamin D maximized control of these parameters. This post-hoc analysis of OPTIMA data assessed the impact of reducing or increasing the dose of concomitant vitamin D on PTH, P and Ca in patients receiving cinacalcet. METHODS: Dialysis patients with mean baseline intact PTH (iPTH) 300-800 pg/ml (31.8-84.8 pM) received doses of cinacalcet titrated to achieve an iPTH of 150-300 pg/ml (15.9-31.8 pM). The dose of vitamin D could then be decreased to further reduce serum P or Ca, or increased/initiated to further decrease PTH levels if iPTH >300 pg/ml or to increase Ca if Ca <8.0 mg/dl (2.0 mM). RESULTS: Vitamin D dose was assessed for 345 patients during a 23-week period. A total of 91 and 129 patients had an increase or decrease in vitamin D dose, respectively. By study end, mean iPTH, P, and Ca were similar in both vitamin D groups, although there were differences in biochemical parameters between groups at the start of the study. There were statistically significant reductions from baseline to study end in iPTH and Ca in both groups (p < 0.001). Although P was significantly reduced by week 23 in the group in which vitamin D dose was decreased (p = 0.007), the reduction in P was less and did not achieve significance in the group in which vitamin D dose was increased (p = 0.71). CONCLUSIONS: After initiating cinacalcet, the dose of vitamin D can be adjusted to maximize reductions in PTH, P and Ca; however, vitamin D-induced decreases in PTH need to be balanced with the diminished response in P and Ca.

Inducible nitric oxide synthase mediates hippocampal caspase-3 activation in pneumococcal meningitis.

Brain damage in bacterial meningitis is still a major problem. More knowledge about the triggers and mechanisms of neuronal damage in bacterial meningitis is needed to improve outcome in bacterial meningitis. The most common bacterial meningitis pathogen--Streptococcus pneumoniae--causes caspase activation and neuronal apoptosis in the hippocampus via its toxins and extensive inflammatory potential. Nitric oxide (NO)--produced by inducible nitric oxide synthase (iNOS)--is a major inflammatory mediator clearly upregulated in the cerebrospinal fluid during pneumococcal meningitis. However, its effects in bacterial meningitis are still controversial. This article demonstrates that genetic inactivation of iNOS results in a marked reduction of caspase-3-mediated neuronal damage in experimental murine pneumococcal meningitis. Protection of hippocampal neurons in iNOS knockout mice was not due to differences in intrathecal growth of S. pneumoniae and must therefore be attributed to differences of host inflammatory mediators. This indicates that NO plays an important role in hippocampal caspase-3 activation during pneumococcal meningitis.

Intravenous C.E.R.A. maintains stable haemoglobin levels in patients on dialysis previously treated with darbepoetin alfa: results from STRIATA, a randomized phase III study.

BACKGROUND: Extending the administration interval of erythropoiesis-stimulating agents (ESAs) represents an opportunity to improve the efficiency of anaemia management in patients with chronic kidney disease (CKD). However, effective haemoglobin (Hb) maintenance can be challenging with epoetin alfa and epoetin beta administered at extended intervals. C.E.R.A., a continuous erythropoietin receptor activator, has a unique pharmacologic profile and long half-life ( approximately 130 h), allowing administration at extended intervals. Phase III results have demonstrated that C.E.R.A. administered once every 4 weeks effectively maintains stable Hb levels in patients with CKD on dialysis. METHODS: STRIATA (Stabilizing haemoglobin TaRgets in dialysis following IV C.E.R.A. Treatment for Anaemia) was a multicentre, open-label randomized phase III study to evaluate the efficacy and safety of intravenous C.E.R.A. administered once every 2 weeks (Q2W) for Hb maintenance following direct conversion from darbepoetin alfa (DA). Adult patients on dialysis receiving stable intravenous DA once weekly (QW) or Q2W were randomized (1:1) to continue their current DA regimen (n = 156) or receive intravenous C.E.R.A. Q2W (n = 157) for 52 weeks. Doses were adjusted to maintain Hb levels within +/- 1.0 g/dl of baseline and between 10.0 and 13.5 g/dl. The primary endpoint was the mean Hb change between baseline and the evaluation period (weeks 29-36). RESULTS: Most patients (>80%) received DA QW before randomization. The mean (95% CI) difference between C.E.R.A. and DA in the primary endpoint was 0.18 g/dl (-0.05, 0.41), within a pre-defined non-inferiority limit. C.E.R.A. was clinically non-inferior to DA (P < 0.0001) in maintaining Hb levels. Both treatments were well tolerated. CONCLUSIONS: Stable Hb levels were successfully maintained in patients on haemodialysis directly converted to Q2W intravenous C.E.R.A. from DA.

The OPTIMA study: assessing a new cinacalcet (Sensipar/Mimpara) treatment algorithm for secondary hyperparathyroidism.

BACKGROUND AND OBJECTIVES: Cinacalcet, a novel calcimimetic, targets the calcium-sensing receptor to lower parathyroid hormone (PTH), calcium, and phosphorus levels in dialysis patients with secondary hyperparathyroidism (SHPT). This study compared the efficacy of a cinacalcet-based regimen with unrestricted conventional care (vitamin D and phosphate binders) for achieving the stringent National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) targets for dialysis patients. STUDY DESIGN: In this multicenter, open-label study, hemodialysis patients with poorly controlled SHPT were randomized to receive conventional care (n = 184) or a cinacalcet-based regimen (n = 368). Doses of cinacalcet, vitamin D sterols, and phosphate binders were adjusted during a 16-wk dose-optimization phase with the use of algorithms that allowed cinacalcet to be used with adjusted doses of vitamin D. The primary end point was the proportion of patients with mean intact PTH < or =300 pg/ml during a 7-wk efficacy assessment phase. RESULTS: A higher proportion of patients receiving the cinacalcet-based regimen versus conventional care achieved the targets for PTH (71% versus 22%, respectively; P < 0.001), Ca x P (77% versus 58%, respectively; P < 0.001), calcium (76% versus 33%, respectively; P < 0.001), phosphorus (63% versus 50%, respectively; P = 0.002), and PTH and Ca x P (59% versus 16%, respectively, P < 0.001), and allowed a 22% reduction in vitamin D dosage in patients receiving vitamin D at baseline. Achievement of targets was greatest in patients with less severe disease (intact PTH range, 300 to 500 pg/ml) and the cinacalcet dose required was lower in these patients (median = 30 mg/d). CONCLUSIONS: Compared with conventional therapy, a cinacalcet-based treatment algorithm increased achievement of KDOQI treatment targets in dialysis patients in whom conventional therapy was no longer effective in controlling this disease.

Protection from brain damage and bacterial infection in murine stroke by the novel caspase-inhibitor Q-VD-OPH.

Infarction size and infections are important determinants of stroke outcome in humans. Bacterial infections are promoted by stroke-induced immunodeficiency which in experimental stroke is mainly characterized by extensive lymphocyte apoptosis and dysfunction. Pharmacological inhibition of caspases may improve stroke outcome not only by reducing apoptotic brain damage but also by attenuating stroke-induced immunodeficiency. We investigated the effects of systemic administration of the novel, non-toxic caspase-inhibitor quinolyl-valyl-O-methylaspartyl-[-2,6-difluorophenoxy]-methyl ketone (Q-VD-OPH) on stroke-induced neuronal and lymphocyte apoptosis, susceptibility to infections, and mortality in a murine model of stroke induced by middle cerebral artery occlusion (MCAO). Q-VD-OPH reduced ischemic brain damage and stroke-induced programmed cell death in thymus and spleen, decreased susceptibility to post-stroke bacteremia, and improved survival. Therefore, Q-VD-OPH may be a promising therapeutic agent in stroke.

Pneumolysin causes neuronal cell death through mitochondrial damage.

Bacterial toxins such as pneumolysin are key mediators of cytotoxicity in infections. Pneumolysin is a pore-forming toxin released by Streptococcus pneumoniae, the major cause of bacterial meningitis. We found that pneumolysin is the pneumococcal factor that accounts for the cell death pathways induced by live bacteria in primary neurons. The pore-forming activity of pneumolysin is essential for the induction of mitochondrial damage and apoptosis. Pneumolysin colocalized with mitochondrial membranes, altered the mitochondrial membrane potential, and caused the release of apoptosis-inducing factor and cell death. Pneumolysin induced neuronal apoptosis without activating caspase-1, -3, or -8. Wild-type pneumococci also induced apoptosis without activation of caspase-3, whereas pneumolysin-negative pneumococci activated caspase-3 through the release of bacterial hydrogen peroxide. Pneumolysin caused upregulation of X-chromosome-linked inhibitor of apoptosis protein and inhibited staurosporine-induced caspase activation, suggesting the presence of actively suppressive mechanisms on caspases. In conclusion, our results indicate additional functions of pneumolysin as a mitochondrial toxin and as a determinant of caspase-independent apoptosis. Considering this, blocking of pneumolysin may be a promising cytoprotective strategy in pneumococcal meningitis and other infections.