Strain-level bacterial identification by CeO2-catalyzed MALDI-TOF MS fatty acid analysis and comparison to commercial protein-based methods.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid approach for clinical bacterial identification. However, current protein-based commercial bacterial ID methods fall short when differentiating closely related species/strains. To address this shortcoming, we employed CeO2-catalyzed fragmentation of lipids to produce fatty acids using the energy inherent to the MALDI laser as a novel alternative to protein profiling. Fatty acid profiles collected from Enterobacteriaceae, Acinetobacter, and Listeria using CeO2-catalyzed metal oxide laser ionization (MOLI MS), processed by principal component analysis, and validated by leave-one-out cross-validation (CV), showed 100% correct classification at the species level and 98% at the strain level. In comparison, protein profile data from the same bacteria yielded 32%, 54% and 67% mean species-level accuracy using two MALDI-TOF MS platforms, respectively. In addition, several pathogens were misidentified by protein profiling as non-pathogens and vice versa. These results suggest novel CeO2-catalyzed lipid fragmentation readily produced (i) taxonomically tractable fatty acid profiles by MOLI MS, (ii) highly accurate bacterial classification and (iii) consistent strain-level ID for bacteria that were routinely misidentified by protein-based methods.

Incidence of and risk factors for falls among adults with an intellectual disability.

BACKGROUND: Falls among people with intellectual disability (ID) occur at a younger age than the general population and are a significant cause of injury and hospitalisation. There is very limited research investigating risk factors for falls among people with ID and none with people living outside of formal care arrangements, either independently or with their family.We used a medical chart audit to identify the incidence and risk factors for falls among people with ID living in a variety of settings. METHODS: We retrospectively identified 114 consecutive patients, aged 18 years and over who attended a clinic for people with developmental disabilities within a 15-month period. Fall information was measured by carer recall of falls in the past 12 months. Potential risk factors were extracted from medical reports and a patient information questionnaire. Potential predictors were identified using univariate analysis and entered into a multiple logistic regression. RESULTS: Of 114 participants, 39 (34%) reported a fall in the previous 12 months.The number of reported falls was similar for formal care and non-formal care arrangements.The vast majority of fallers (84%) reported sustaining an injury from a fall and many potential risk factors were identified. Multivariate analysis revealed having seizures in the past 5 years, a history of fracture and increasing age were risk factors for falls. CONCLUSIONS: Falls are a significant health concern for adults with ID of all ages as a result of their incidence and the resulting injuries. Falls appear to be equally an issue for people residing in formal and non-formal care accommodation. Further research is needed to develop screening tools and interventions for this population.

Comparison of S(-)-bupivacaine with racemic (RS)-bupivacaine in supraclavicular brachial plexus block.

Bupivacaine is used widely as a local anaesthetic but has potential for severe cardiovascular and central nervous system (CNS) toxicity. It has an asymmetric carbon atom giving it a chiral centre, and the commercial preparation is a racemic mixture of its two enantiomers: dextro or R(+)-bupivacaine and levo or S(-)-bupivacaine. Preclinical studies have demonstrated reduced cardiotoxicity and CNS toxicity for S(-)-bupivacaine. In this study we have compared the clinical efficacy of S(-)-bupivacaine with racemic RS-bupivacaine for supraclavicular brachial plexus block in 75 patients undergoing elective hand surgery. Patients received 0.4 ml kg-1 of either 0.25% or 0.5% S(-)-bupivacaine or 0.5% RS-bupivacaine in a randomized, double-blind study. Clinical assessments of sensory and motor block were performed at regular intervals. There were no significant differences in onset time, dermatomal spread or duration of both sensory and motor block between the three groups (the power of the study was 81% to detect a 4-h difference in duration). Duration of sensory block was prolonged with wide interpatient variation: 892 (SD 250) min, 1039 (317) min and 896 (284) min for 0.25% S(-)-bupivacaine, 0.5% S(-)-bupivacaine and 0.5% RS-bupivacaine, respectively. There were no differences in the overall success rate of the technique. We conclude that S(-)-bupivacaine was suitable for local anaesthetic use in brachial plexus block anaesthesia.

Extradural S(-)-bupivacaine: comparison with racemic RS-bupivacaine.

Bupivacaine has a chiral centre and is currently available as a racemic mixture of its two enantiomers: R(+)-bupivacaine and S(-)-bupivacaine. Preclinical studies have demonstrated that there is enantiomer selectivity of action with the bulk of central nervous system and cardiovascular toxicity residing with the R(+) isomer. The aim of this study was to compare the clinical efficacy and safety of S(-)-bupivacaine with racemic RS-bupivacaine for extradural anaesthesia. We studied 88 patients undergoing elective lower limb surgery under lumbar extradural anaesthesia who received 15 ml of 0.5% or 0.75% S(-)-bupivacaine, or 0.5% RS-bupivacaine in a randomized, double-blind study. There was no difference in onset time, maximum spread of sensory block or intensity of motor block between the three groups. Duration of sensory block was significantly longer for 0.75% S(-)-bupivacaine. We conclude that S(-)-bupivacaine has similar local anaesthetic characteristics to RS-bupivacaine when used for extradural anaesthesia.

A comparison of epidural infusions of fentanyl or pethidine with bupivacaine in the management of postoperative pain.

A double-blind randomised clinical trial was undertaken in 40 patients undergoing major abdominal surgery. Postoperative pain relief was provided using epidural infusions of 0.06% bupivacaine with fentanyl 4 micrograms.ml-1 (n = 20) (group F) or with pethidine 1.5 mg.ml-1 (n = 20) (group P). Postoperative pain scores using a visual analogue scale (0-100 mm) were not significantly different between the two groups. Median pain scores were 0-19 mm at all times of assessment indicating that good analgesia was provided by both regimens. There was no significant difference between the epidural infusion rates in the two groups. The side effects and effect on pulmonary function were similar in each group. Nine patients were withdrawn from the study (four from group F, five from group P) due to failure of the epidural technique or other complications. Fourteen patients, equally distributed, required a total of 24 epidural 'top-ups' by an anaesthetist because of inadequate analgesia. We demonstrated no advantage with epidural pethidine over fentanyl when used by infusion in combination with bupivacaine in the management of postoperative pain.

Dosimetric properties of p(90)+(Be + Ta) and p(101)+(Be + Al) neutrons.

Dosimetric data were obtained for p(90) + (Be + Ta) and p(101) + (Be + A1) radiation with field size 9 x 11 cm at a 125-cm SSD impinging on a tissue-equivalent liquid phantom with density 1.10. The radiation was unfiltered or filtered by 10 cm of polyethylene. Dose rates measured with a 0.5-cm3 ion chamber at a depth of 5 cm ranged from 0.046 Gy min-1 microA-1 for filtered p(90) + (Be + Ta) to 0.11 Gy min-1 microA-1 for unfiltered p(101) + (Be + A1). Neutron time of flight energy spectra in air averaged above 10 MeV indicate mean neutron energies ranging from 42.0-51.4 MeV for the four beams under study. The central axis depths at which 50% dose attentuation occurred ranged from 15 to 20 cm for these beams. At 3 cm depth the gamma dose component of the total p(101) + (Be + A1) dose was 14.5%, or 17% with filtration.

Gamma dose measurement in a d(80) + Be neutron beam.

The gamma-ray dose component of a d(80) + Be neutron beam was measured with a 6Li-shielded Geiger-Mueller counter in a tissue-equivalent liquid phantom. The proportion of gamma-ray dose to total dose increased from 0.07 near the surface to 0.09 at 25 cm depth. Due to thermal neutron sensitivity, the G-M count rate increased by 25% in the absence of 6Li shielding.