Acute chest syndrome is associated with single nucleotide polymorphism‐defined beta globin cluster haplotype in children with sickle cell anaemia

Genetic diversity at the human β‐globin locus has been implicated as a modifier of sickle cell anaemia (SCA) severity. However, haplotypes defined by restriction fragment length polymorphism sites across the β‐globin locus have not been consistently associated with clinical phenotypes. To define the genetic structure at the β‐globin locus more thoroughly, we performed high‐density single nucleotide polymorphism (SNP) mapping in 820 children who were homozygous for the sickle cell mutation (HbSS). Genotyping results revealed very high linkage disequilibrium across a large region spanning the locus control region and the HBB (β‐globin gene) cluster. We identified three predominant haplotypes accounting for 96% of the β^S‐carrying chromosomes in this population that could be distinguished using a minimal set of common SNPs. Consistent with previous studies, fetal haemoglobin level was significantly associated with β^S‐haplotypes. After controlling for covariates, an association was detected between haplotype and rate of hospitalization for acute chest syndrome (ACS) (incidence rate ratio 0·51, 95% confidence interval 0·29–0·89) but not incidence rate of vaso‐occlusive pain or presence of silent cerebral infarct (SCI). Our results suggest that these SNP‐defined β^S‐haplotypes may be associated with ACS, but not pain or SCI in a study population of children with SCA.     

Efficacy and Safety of Indacaterol,a New 24-hour β 2-Agonist,in Patients with Asthma: A Dose-Ranging Study

Background. Indacaterol is a new once-daily inhaled β₂-agonist in clinical development for asthma as a component of a fixed-dose combination with an inhaled corticosteroid. Objectives. To investigate the efficacy and safety of indacaterol in patients with chronic persistent asthma. Methods. A total of 115 patients were randomized in a double-blind, incomplete-block cross-over design to sequences of four 7-day treatment periods (separated by 7-day washouts) with indacaterol 100, 200, 300, 400, or 600 μ g or placebo, once daily, via single-dose dry-powder inhaler. After the fourth washout, patients received 1 day of open-label formoterol 12 μ g twice daily. Forced expiratory volume in 1 second (FEV₁) was measured for 24 hours post-dose on days 1 and 7. Results. For standardized (with respect to time) FEV₁ area under the curve at 22 to 24 hours (AUC_22–24h) on day 1, indacaterol doses ≥200 μ g were superior to placebo (p < 0.05) and similar or greater than formoterol 12 μg twice daily. By day 7, mean differences from placebo in FEV₁ standardized AUC_22–24h were 0.08, 0.16, 0.15, 0.11, and 0.16 L for indacaterol 100, 200, 300, 400, and 600 μg, respectively (all p < 0.05 vs. placebo). Mean FEV₁ for indacaterol doses ≥ 200 μg on day 7 was higher than placebo (p < 0.05) pre-dose and at all post-dose time points. AEs were generally mild in severity; no serious AEs occurred. No clinically meaningful differences were observed between treatments in any safety assessments. Conclusions. Once-daily indacaterol demonstrated sustained 24-hour bronchodilator efficacy, with similar efficacy on days 1 and 7, and was generally well tolerated.     

A kit to facilitate and standardize the processing of sputum for measurements of airway inflammation

BACKGROUND:

The use of inflammometry has been shown to be effective for managing asthma. However, sputum processing can be time consuming. Furthermore, methods of sputum processing can vary among facilities. To help with standardization and to simplify the procedure for laboratory staff, a novel, commercially available processing device (Accufilter, Cellometrics Inc, Canada) has been developed.

OBJECTIVE:

To assess the validity of the Accufilter device and kit for recovery of treated specimens, and for quantitative sputum inflammatory cell counts by comparing intrasample measurements with those using the same procedure without the Accufilter device and kit.

METHODS:

The present study was a wet laboratory comparison of induced sputum cell counts obtained from sputum processed with versus without the device and kit. Comparisons of each sputum specimen were performed by the same technologist in random order.

RESULTS:

A total of 39 samples were processed using both the standard method and the Accufilter device. The intraclass correlation coefficients were high for the weight of the filtrate, and for eosinophil and neutrophil differential counts.

CONCLUSION:

A good degree of agreement of results was apparent when the two methods were compared. The differences noted between both methods were minimal and did not modify clinical interpretation. The use of the Accufilter device and kit can be used in place of the standard method for sputum quantitative analysis, especially in centres with large sample loads.     

Endotoxic shock alters the pharmacokinetics of lidocaine and monoethylglycinexylidide

Significant hepatic dysfunction occurs following endotoxin administration. Although the metabolism of lidocaine to one of the primary metabolites of lidocaine, monoethylglycinexylidide (MEGX), has been used as a marker of hepatic function under various conditions, it remains unknown whether these compounds can be used in vivo to evaluate hepatic function in a rat model of endotoxic shock. To study this, cytochrome P450-3A4 (CYP3A4) was determined after harvesting hepatic microsomes, hepatic blood flow was determined using radioactive microspheres, and the pharmacokinetics of lidocaine and MEGX were evaluated. Adult male Sprague-Dawley rats were divided into endotoxin (45 mg/kg, intraperitoneally; n = 28) or control (n = 32) groups. The CYP3A4 was significantly reduced after endotoxic shock. Carboxylesterase (hydrolase S) content, which was used as a control for microsomal protein, was not significantly different between groups. Total hepatic blood flow was significantly decreased (36.2 +/- 8.4 mL/min/100 g tissue vs. 120.4 +/- 10.6 mL/min/100 g tissue), which was due to the decreased portal blood flow. For the lidocaine and MEGX experiment, lidocaine (2 mg/kg) was administered followed by serial blood samples collected up to 2 h for determination of serum lidocaine and MEGX concentrations. Mean arterial pressure (MAP) was recorded throughout the experiment. The MAP was significantly lower in the endotoxin treated rats vs. control 7.5 to 8 h following endotoxin administration. Serum concentrations of lidocaine were higher in endotoxic shock versus control animals at 2 h following lidocaine administration (1.5 +/- 0.13 mg/L vs. 0.11 +/- 0.03 mg/L). Similarly, MEGX concentrations were significantly higher in endotoxic shock versus control animals (0.55 +/- 0.04 mg/L vs. 0.16 +/- 0.02, respectively) under such conditions. These data demonstrate that the elimination of lidocaine and MEGX is impaired during endotoxic shock. The elevated lidocaine and MEGX concentrations are likely to be the result of primarily reduced hepatic blood flow and secondarily due to impaired CYP450, one of which was CYP3A4. The reduced elimination of MEGX concentrations is not due to decreased hepatic metabolism of the compound via carboxylesterase. The ratio of MEGX to lidocaine concentrations, which decreased significantly following endotoxic shock, appears to be a useful measure of hepatic function during endotoxic shock where profound reductions of hepatic blood flow are observed in addition to significant reductions in CYP450. The use of only MEGX concentrations in this endotoxic shock model is not useful in evaluating liver function.