The influence of matrix type, diurnal rhythm and sample collection and processing on the measurement of plasma β-amyloid isoforms using the INNO-BIA plasma Aβ forms multiplex assay

Objective  The aim of the study was to determine the extent to which plasma matrix types, diurnal rhythm and sample collection and processing procedures contribute to overall variability of measurements with the INNO-BIA plasma Aβ forms assay. Methods  Plasma samples from healthy volunteers were collected at BARC-CRI. Analyte concentrations from various plasma matrix types (EDTA, heparin, fluoride) were compared to serum after collection of blood in commercial plastic and glass tubes. Sample processing variables including time and temperature before and after centrifugation, centrifugal force and plasma dilution factor were also investigated. Diurnal variability in plasma Aβ isoforms was determined in 29 healthy volunteers by analysis of EDTA plasma specimens serially collected over 24 hours and stored frozen following oral administration of a placebo treatment. All plasma samples from a given individual and experiment were analyzed in a single analytical run. Results  Highest Aβ levels were obtained using EDTA-plasma samples (in contrast to serum, heparin, citrate, or fluoride). Addition of aprotinin to EDTA plasma had no effect on Aβ peptide recovery. The elapsed time and temperature exposure, before and after sample processing affects the recovery of Aβ isoforms. Analyte recovery was not significantly affected by the presence of platelets in plasma samples. At the subject level, analysis of serially collected EDTA plasma specimens from healthy volunteers revealed no evidence of diurnal variation in any of the Aβ isoforms investigated and results from samples collected on a monthly basis showed only very limited intra-individual variation. Conclusions  Optimal recovery of Aβ peptides was obtained from blood drawn into EDTA tubes and processed within 4 h. Plasma that was refrigerated after separation and analysed within 4 h gave comparable results to samples immediately processed and frozen at −70 °C.     

Postural drainage and gastro-oesophageal reflux in infants with cystic fibrosis

Gastro-oesophageal reflux is increased in cystic fibrosis and it is possible that postural drainage techniques may exacerbate reflux, potentially resulting in aspiration and further impairment of pulmonary function. AIM: To evaluate the effects of physiotherapy with head down tilt (standard physiotherapy, SPT) on gastroesophageal reflux and to compare this with physiotherapy without head down tilt (modified physiotherapy, MPT). METHOD: Twenty (mean age 2.1 months) infants with cystic fibrosis underwent 30 hour oesophageal pH monitoring during which SPT and MPT were carried out for two sessions each on consecutive days. RESULTS: The number of reflux episodes per hour, but not their duration, was significantly increased during SPT compared with MPT (SPT 2.5 (0.4) v MPT 1.6 (0.3), p = 0.007) and to background (1.1 (0.)1, p = 0.0005). Fractional reflux time was also increased during SPT (11.7 (2.6)%) compared with background (6.9 (1.3)%) p = 0.03) but not compared with MPT (10.7 (2.7)%). There was no significant difference between MPT and background for number of reflux episodes, their duration, or fractional reflux time. CONCLUSIONS: SPT, but not MPT, was associated with a significant increase in gastro-oesophageal reflux in infants with cystic fibrosis.     

The effect of glycopyrrolate on postoperative pain and analgesic requirements following laparoscopic sterilisation

In order to evaluate the contribution of tubal spasm to pelvic pain following laparoscopic sterilisation, we have studied the effect of glycopyrrolate, an anticholinergic agent with antispasmodic properties, on 60 ASA 1 and 2 patients presenting as day-cases for laparoscopic sterilisation using Filshie clips. In a randomised, double-blind, controlled trial, patients received either glycopyrrolate 0.3mg or saline intravenously prior to induction of anaesthesia. Compared with the control group, patients receiving glycopyrrolate had significantly reduced immediate postoperative pain scores (p < 0.02) and required significantly less postoperative morphine (p < 0.01). Nausea, vomiting and anti-emetic requirements were also reduced though not significantly. We conclude that glycopyrrolate 0.3mg at induction of anaesthesia is an effective method of improving the quality of recovery after day-case laparoscopic sterilisation using clips.