Standardless semiquantitative analysis of metals using single-shot laser ablation inductively coupled plasma time-of-flight mass spectrometry.

A method has been developed that allows the accurate, standardless measurement of the elemental composition of metal samples from single laser ablation (LA) pulses. This technique provides a fast, low-sample-consumption means for the characterization of samples having a range of matrixes. The method directly compares adjusted elemental signals with the total mass spectrometric signal to produce relative percent composition information. Three mathematical techniques were used to determine the accuracy and precision of single-shot LA measurement. Comparison of the techniques showed that a linear regression calculation, which plots individual elemental signals as a function of the summed signal for all elements in the sample on a point-by-point basis during a laser ablation transient proved superior. The simultaneous extraction capability of time-of-flight mass spectrometry permits the sampling of all analytes from any temporal position within the transient laser ablation pulse, thereby reducing quantitation error. A typical concentration dynamic range of 3 orders of magnitude, from 0.1 to 100%, was achieved. However, by measuring low-abundance isotopes for matrix elements, the dynamic range of the technique was extended to 4 orders of magnitude. The new technique is largely immune to sample matrix effects commonly experienced in laser ablation. By performing a complete elemental analysis from a single ablation pulse, high spatial resolution should be achieved.

Bioconcentration and distribution of 4-tert-octylphenol residues in tissues of the rainbow trout (Oncorhynchus mykiss).

Branched chain alkylphenols are weak oestrogen mimics which are present in the aquatic environment and have been implicated in the feminisation of fish. This study reports the biotransformation, bioconcentration and tissue distribution of the xenoestrogen 4-tert-octylphenol (t-OP) in juvenile rainbow trout. Fish were exposed for 10 days to a concentration of 4 micrograms/l of [14C] t-OP in a flow-through system and were sampled after 1, 4, 7 and 10 days of exposure. t-OP residues were extracted from all tissues and analysed by radio-high-performance liquid chromatography. After 1 day of exposure radioactive residues were detected in all tissues and reached steady state conditions in the whole fish after 4 days of exposure. The concentration of t-OP residues were highest in bile, followed by faeces, pyloric caeca, liver and intestine. In these tissues the majority of alkylphenol was in the form of two metabolites which were identified by gas chromatography-mass spectroscopy as the glucuronide conjugates of t-OP and t-octylcatechol. t-OP accumulated as the parent compound in fat with a bioconcentration factor (BCF) of 1190, and in brain, muscle, skin, bone, gills, and eye with BCFs of between 100 and 260. This study suggests that exposure to water-borne alkylphenols results in rapid conjugation and elimination of the chemical via the liver/bile route, but that high amounts of the parent xenoestrogen can accumulate in a variety of other fish tissues.

Prediction of haloperidol steady-state levels in plasma after a single test dose.

Because of large interindividual variabilities in the pharmacokinetics of haloperidol (HPDL), empirically adjusting the dose to achieve steady-state levels in plasma (Css) is a time-consuming process. We report a method to individualize dose to achieve a desired Css from an observed drug level 24 hours after a single 15-mg test dose of HPDL. Drug-free schizophrenic and schizo-affective patients were blindly and randomly assigned to achieve a low (< 5 ng/ml), medium (10-18 ng/ml), or high (> 25 ng/ml) Css range of HPDL. On day 1 of the study, each patient received an oral "test" dose of HPDL (15 mg), and blood was drawn 24 hours later to determine drug levels in plasma (C24h). The first 34 patients (group I) were then maintained empirically on 2, 5 to 8, or 10 to 15 mg twice daily of oral HPDL concentrate for 5 days to achieve a low, medium, or high Css range, respectively. For the next 58 patients (group II), the dose of HPDL to achieve the assigned Css range was computed by using C24h in a prediction formula. Application of the C24h correctly predicted the maintenance dose required to achieve the Css in 73.2% of the cases. Further, there was a highly significant correlation (R2 = 0.877, p < 0.0001) between the predicted dose and the actual dose required to achieve the targeted Css range. On the basis of these results, we have formulated a nomogram to help predict the maintenance dose required to achieve low, medium, or high HPDL targeted ranges at various C24h values.

Respiratory allergy and specific immunoglobin E and immunoglobin G antibodies to reactive dyes used in the wool industry.

Respiratory symptoms among six employees in wool dye-houses in the United Kingdom were investigated. Clinical histories revealed that all had work-related respiratory symptoms, which they associated with exposure to Lanasol dyes. Five of the six subjects had specific Immunoglobin E to human serum albumin conjugates of one or more of the dyes to which they were exposed, providing evidence of sensitization to these dyes. In two subjects there was a definite association between symptoms to a particular dye, and specific IgE to an albumin conjugate of that dye. Specific IgG was found in exposed subjects, irrespective of the presence of allergic symptoms, indicating that specific IgG reflects exposure rather than clinical sensitization. Four of the six subjects had specific IgG4; this was only present in the subjects with respiratory allergy and specific IgE.

Familial aspects of Gilles de la Tourette syndrome.

The authors present two cases in which Gilles de la Tourette syndrome was present in at least two family members: the first case is a mother and her son and the second an uncle and his nephew. the increasing severity of the syndrome from one generation to the next and some similar clinical features in the two cases are noted. The authors also speculate that the incidence of family cases of Tourette syndrome may be underestimated because of the painstaking efforts required to obtain this kind of history.