GC-MS analysis of cuticular lipids in recent and older scavenger insect puparia. An approach to estimate the postmortem interval (PMI).

An analytical method was developed to characterize puparia cuticular lipids (hydrocarbons, waxes) and to compare the molecular distribution patterns in the extracts from either recent or older puparia. Acid-catalyzed transesterification and solvent extraction and purification, followed by combined gas chromatography coupled to mass spectrometry, were optimized for the determination of hydrocarbons and fatty acid ethyl esters from transesterified waxes, extracted from a single species of a fly scavenger (Hydrotaea aenescens Wiedemann, 1830). Comparison between recent (2012) or older (1997) puparia contents has highlighted significant composition differences, in particular, a general decrease of the chain length in the n-alkane distribution pattern and, on the contrary, an increase of the ester chain length. Both extracts contain traces of three hopane hydrocarbon congeners. Preliminary results evidence the change in puparia lipid composition over time, thus potentially providing new indices for estimating postmortem interval.

Safety of midazolam for sedation of HIV-positive patients undergoing colonoscopy.

OBJECTIVES: Because of concerns regarding interactions between midazolam and antiretroviral therapy (ART), alternative sedatives are sometimes used during procedural sedation. Our objective was to compare outcomes in patients on ART who received intravenous (iv) midazolam vs. iv diazepam, a second-line agent, during colonoscopy. METHODS: We conducted a retrospective analysis of adult HIV-positive patients who underwent colonoscopy over a 3.5-year period. Primary outcomes were sedation duration, nadir systolic blood pressure (SBP), nadir oxygen saturation, abnormal cardiac rhythm, and change in level of consciousness using a standardized scale. We calculated rates of adverse events according to benzodiazepine use and identified risk factors for complications using univariate and multivariate analyses. RESULTS: We identified 136 patients for this analysis: 70 received midazolam-based sedation and 66 received a diazepam-based regimen. There were no significant differences between the two groups with respect to sedation duration (mean 48.0 vs. 45.7 minutes for the midazolam and diazepam groups, respectively; P = 0.68), nadir SBP (mean 97.0 vs. 101.6 mmHg; P = 0.06), nadir oxygen saturation (mean 94.6 vs. 94.8%; P = 0.72) or rate of abnormal cardiac rhythm (11.4 vs. 19.7%; P = 0.18). More patients in the midazolam group experienced a depressed level of consciousness (91% vs. 74% in the diazepam group; P = 0.0075), but no patient required reversal of sedation or became unresponsive. CONCLUSIONS: We did not find evidence that patients who received midazolam for procedural sedation had clinical outcomes statistically different from those who received diazepam. These findings should be confirmed in prospective studies or in a randomized controlled trial.

Safety of enteral naloxone for the reversal of opiate-induced constipation in the intensive care unit.

BACKGROUND: Opiates are the mainstay of analgesia in the intensive care unit (ICU). Unfortunately, constipation is a common adverse effect associated with opioid use. Naloxone is a pure opiate antagonist that is frequently utilized in practice for the prophylaxis or treatment of opiate-induced constipation in the ICU. Despite extensive first pass metabolism in the liver there remains the potential for opiate reversal after oral administration. We sought to assess the safety of enteral naloxone in the ICU for the treatment of opiate-induced constipation. METHODS: Patients who were ordered enteral naloxone while in the ICU were identified through the Pharmacy's computer system. Patients were included in the data analysis if they had received at least one dose of enteral naloxone and had received standing opiates for at least 48 h prior to the initial naloxone dose. Patients were excluded from data analysis if the Richmond agitation-sedation scale (RASS) score was not utilized, they were paralysed or the medical record indicated that extubation was planned within the following 24 h. Data points were recorder at the following times with respect to each naloxone dose administered; time -2, -1, 0, 1, 2 and 4 h. The following data points were collected before and after each naloxone dose; blood pressure, heart rate, respiratory rate, RASS score, pain assessment score (recorded as present or absent), midazolam dose, propofol dose and fentanyl dose. In order to assess for possible opiate reversal the peak fentanyl, propofol and midazolam dose, vital sign value, RASS score and pain score were compared before and after each dose of naloxone. RESULTS: The mean naloxone dose was 3.6 +/- 0.9 mg. There was no significant change in RASS score around the naloxone doses, -2.9 +/- 1.4 before and -2.8 +/- 1.6 after (P = 0.28). There were no significant changes in mean fentanyl, propofol or midazolam dose around naloxone administration. There were also no significant changes in heart rate, blood pressure and respiratory rate or in the presence of pain. CONCLUSION: These results demonstrate that the administration of enteral naloxone to patients on intravenous opiates in the ICU setting was not associated with changes in sedation score, vital signs, fentanyl dose, midazolam dose or propofol dose.

Feasibility of dexmedetomidine in facilitating extubation in the intensive care unit.

BACKGROUND: Spontaneous breathing trials (SBT) and intermittent mandatory ventilation (IMV) are common techniques utilized to expedite the ventilator weaning process. These techniques often require the reduction and/or discontinuation of sedatives and analgesics. Reducing these medications can lead to agitation and the inability to conduct SBTs or weaning by IMV. Adding dexmedetomidine (dex), a potent alpha-2-adrenergic receptor agonist that possesses sedative, anxiolytic and analgesic effects without causing significant respiratory depression, may facilitate extubation in these patients. OBJECTIVE: To assess the feasibility of adding dex to facilitate extubation in a group of difficult-to-extubate patients secondary to agitation. METHODS: Mechanically ventilated patients who were deemed difficult to wean and extubate secondary to agitation were evaluated for dex therapy. Inclusion criteria were location in an intensive care unit, intubated and mechanically ventilated, required IV sedation, deemed suitable by unit criteria for weaning and extubation within 24 h of dex initiation, previous attempts at weaning sedation and/or analgesia resulted in agitation causing either severe patient ventilator dyssynchrony, prolong need for intubation, or an inability to conduct a successful SBT. Additional inclusion criteria were unsuccessful use of traditional intravenous agents to control agitation. Recommended dex dosing was a bolus of 1 microg/kg followed by an infusion of 0.2-0.7 microg/kg/h. RESULTS: Twenty-five patients were evaluated for dex therapy with 20 meeting the criteria to treat. All had failed prior attempts at weaning. Fourteen of the 20 patients were successfully weaned and extubated and one patient was reintubated within 48 h, giving a 65% success rate. Heart rate trended down after dex initiation in most patients but did not result in the discontinuation of dex in any patient. The addition of dex was associated with minimal changes in mean arterial pressure. CONCLUSIONS: Dexmedetomidine was initiated in a group of mechanically ventilated patients who failed previous attempts at weaning and extubation secondary to agitation. After dex initiation, 65% of the patients was successfully extubated. Dexmedetomidine was associated with a reduction in concomitant sedative and analgesic use with minimal adverse effect.

Determination of traces of pesticides in water by solid-phase extraction and liquid chromatography-ionspray mass spectrometry.

A multi-residue analytical method for six pesticides (atrazine, hydroxyatrazine, carbofuran, promecarb, linuron and monolinuron) in drinking water has been developed. The method combines liquid chromatography and mass spectrometry using an ionspray interface. The linearity domain, as well as the limits of detection and quantification, were determined for each compound. Although satisfactory performance could be achieved, present drinking water regulations (0.1 microgram l-1 for single pesticide) requires a pre-concentration step. This was performed using solid-phase extraction with octadecyl-bonded silica cartridges. The analytical procedure was tested on water samples spiked at the 0.04 and 0.08 microgram l-1 levels, and allowed the determination of the investigated pesticides (except hydroxyatrazine) at these trace concentrations.

Analysis of linear oligogalacturonic acids by negative-ion electrospray ionization mass spectrometry.

Linear oligogalacturonic acids (1,4-linked alpha-D-galacturonic acid oligomers), obtained by partial acid hydrolysis of orange polygalacturonides, were studied by negative-ion electrospray ionization mass spectrometry, without prior sample derivatization. After preparative separation using high-resolution anion-exchange chromatography, some fractions enriched in uronic acids were desalted, transferred into a methanol+water solution adjusted to pH 10, and directly submitted to electrospray ionization mass spectrometry in the negative-ion recording mode. Clear molecular mass assignments of the oligomers, covering a degree of polymerization between 4 and 7, were obtained.

Recent methods for the determination of volatile and non-volatile organic compounds in natural and purified drinking water.

Four analytical protocols for the extraction and preconcentration of organic residues in natural or purified drinking water were investigated and compared: closed loop stripping analysis; simultaneous extraction-distillation; purge and trap analysis; continuous liquid-liquid extraction. Organic extracts were submitted to a variety of separation and identification techniques. Volatiles were determined by conventional capillary column gas chromatography with tandem mass spectrometry, using triple-stage quadrupole instruments. Non-volatile and thermally labile molecules were investigated by several different techniques (high-temperature gas chromatography, capillary column supercritical fluid chromatography, pyrolysis gas chromatography-mass spectrometry, thermospray liquid chromatography with tandem mass spectrometry and conventional fast-atom bombardment with tandem mass spectrometry). Several samples recently examined in the laboratory provide examples of this multitechnique approach for a more complete knowledge of the organic carbon distribution in water-dissolved organic matter, taking into account organic substances with widely different volatilities, polarities and thermal stabilities.

Polypeptide sequencing by liquid chromatography mass spectrometry.

Key steps in a proposed automated system for polypeptide sequencing utilizing a liquid chromatograph mass spectrometer computer system have been tested with mixtures containing up to six model oligopeptides. At the low nanomole level it was possible to obtain complete sequence information for all components in many, but not all, of the mixtures tried. Interpretation of the results is complicated by the presence of numerous side-products formed in the derivatization process. Minimization of such impurities will be necessary to reduce the ambiguity of the sequence information resulting from more complex mixtures, such as those expected from the degradation of larger polypeptides, and to reduce sample requirements to the subnanomole level. However, the present system appears to have unique advantages over other proposed automated methods.