Analysis of fenthion in postmortem samples by HPLC with diode-array detection and GC-MS using solid-phase extraction

Fenthion (O,O-dimethyl-O-[3-methyl-4-(methylthio)-phenyl]-thiophos-phate ) is an organophosphate insecticide. A specific method to quantitate fenthion in postmortem matrices with solid-phase extraction combined with high-performance liquid chromatography-diode-array detection (HPLC-DAD) and gas chromatography-mass spectrometry (GC-MS) is presented. Fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenyl]-thiophosphate) is selected as the internal standard. For sample cleanup, a simple but selective solid-phase extraction is chosen after comparison with traditional liquid-liquid extraction procedures. Homogenized and appropriately diluted aqueous samples are applied, and the analytes are desorbed with 5 mL of dichloromethane. Aliquots of the extract are used for HPLC-DAD and GC-MS analysis, Liquid and GC conditions are as follows: gradient elution with a mixture of methanol and water (10:90 to 90:10, v/v) containing 0.0125M NaOH on an Aluspher RP-Select B column monitoring at 250 nm, and temperature programming from 60 to 300 degrees C on a dimethylpolysiloxane column in the SCAN mode, respectively. This method is applied to a suicidal case involving unsuspected acute intoxication with fenthion (concentration in blood, 3.8 micrograms/mL).

[Simulation of attempted homicide by dog bite in unconscious state]

It is reported on the unusual event of dog scavenging in an unconscious and intoxicated (alcohol) person. Due to the particular circumstances a case of attempted homicide was primarily suspected. Peculiarities of the case were a small dog (dachshund) as the responsible cause and the survival of the injured woman. Intensive and partly deep wounds due to scavenging were found on both shoulders/upper arms in nearly symmetrical order. Vomit from the dog could be assigned to the unconscious person by DNA typing. The typical morphological features of dog bites and injuries due to scavenging, respectively, and the possible motivation of the animal are discussed.

Signal-enhancing switched protocols to study higher-order cognitive tasks with PET

We tested the effectiveness of a switched protocol when it is used to detect signals that result from the study of a higher-order cognitive task with PET. Using language tasks that have been studied extensively in our laboratories, we compared the signal-to-noise ratio (S/N) and statistical significance of the activation signals detected in PET images of regional cerebral blood flow (rCBF), obtained using a standard activation protocol, and of activity concentration, obtained using a switched protocol.

METHODS

Four volunteers were studied with PET while they were performing synonym-generation and word-repetition tasks (activation and baseline tasks, respectively). Each volunteer had three activation/baseline and three baseline/ activation scans. Data for each scan were collected in two frames (60 and 120 sec long). During the first 60 sec, data were collected using a standard activation protocol. Subjects then switched tasks, and acquisition continued for 120 sec. Two images were obtained from each scan: an rCBF image using the first frame and an activity-concentration image using both frames. Images were transformed into Talairach space, subtracted and averaged within and across subjects. Parametric t-statistic images were generated for each protocol, and the magnitude and significance of the activation signals yielded by the two acquisition methods were compared.

RESULTS

All the activation foci detected using measurements of rCBF were detected when the switched protocol was used; this protocol, in addition, yielded better S/N values. The cognitive component introduced by task-switching in switched protocols did not yield extra statistically significant foci. In single subjects, the average improvement in the signal significance from regions of activation, at a 95% confidence level, was between 6% and 25%. When scans were averaged across subjects, the switched protocol yielded improvements in signal statistical significance of up to 38%.

CONCLUSION

We present evidence suggesting that switched protocols can be used to study higher-order cognitive tasks and that they yield activation foci with S/N values that are greater than those of equivalent foci detected using an rCBF protocol. Switched protocols appear to be easy to apply to the testing of higher-order cognitive functions. However, the extra cognitive requirement of switching tasks during data acquisition may be a limiting factor when switched protocols are used to study memory processes.

The effect of lead in tap water on blood lead in children in a smelter town

Hettstedt, a city in eastern Germany with a long history of mining and smelting of non-ferrous ores, has multiple lead waste deposits and the remains of a former lead smelter and a copper-silver smelter. As part of a cross-sectional study, an analysis of lead concentrations in drinking water and in blood was undertaken to determine the impact of lead in drinking water on the internal burden of lead in children. The geometric mean of blood lead levels among children 5-14 years old was 35.0 micrograms/l with a 95% confidence interval (C.I.) of 33.4-36.7. The geometric mean of lead in the random tap water samples was 0.5 microgram/l (95% C.I., 0.5-0.6) and 0.7 microgram/l (95% C.I., 0.6-0.8) in the stagnant tap water samples. Blood lead levels were somewhat correlated with the random water measures but not the stagnant water measures (random sample: r = 0.12, P = 0.012; stagnant sample: r = 0.04, P = 0.396). After adjustment for relevant confounders, lead in drinking water (random sample) was not significantly associated with blood lead levels. Factors that were significantly associated with blood lead included gender, the city area of residence, lead in house dust, regular contact with dogs and dirtiness of the child after playing outdoors. Based on this study, lead in domestic tap water contributed little to the lead exposure of children in the lead contaminated region of Hettstedt.

Regional lumped constant differences and asymmetry in fluorine-18-FDG uptake in temporal lobe epilepsy

To date, there has been no satisfactory explanation for the observation that interictal uptake of the glucose analog [18F]fluorodeoxyglucose (FDG) is consistently reduced in the temporal lobe ipsilateral to the seizure focus in patients with temporal lobe epilepsy. We examined the hypothesis that regional differences in tracer uptake in temporal lobe epilepsy reflect regional differences in the lumped constant (lambda).

METHODS

In 9 control subjects and 10 patients with temporal lobe epilepsy, we obtained regional estimates of lambda by expressing lambda in terms of transfer coefficients for FDG and parameters which are likely to remain constant throughout both the brain and under different functional states.

RESULTS

In the patients, lambda was lower in the temporal lobe ipsilateral to the epileptic focus (0.53 +/- 0.06; p < 0.005) than in the contralateral temporal lobe (0.56 +/- 0.06). Interside differences in lambda were highly correlated with asymmetry in tracer uptake. Furthermore, the use of regional estimates of lambda reduced the asymmetry in estimated rCMRglc in patients with temporal lobe epilepsy but not in controls.

CONCLUSION

In these patients, a change in tracer uptake may not indicate a change in glucose consumption of corresponding magnitude, raising the possibility that in at least some patients with temporal lobe epilepsy, the term hypometabolism does not accurately describe reductions in tracer uptake.

The STR loci HumTPO and HumLPL: population genetic data in eight populations

The two STR systems HumTPO and HumLPL were investigated in eight human populations (Moroccans, Ovambos, Papuans, Australian aborigines, Germans, Turks, Japanese and Chinese). After electrophoresis, seven and eight alleles were identified in the HumTPO and HumLPL systems, respectively. In each population, no deviations from Hardy-Weinberg equilibrium were observed, but considerable differences in phenotype frequencies of each system were found between major ethnic groups.

Clinical characteristics and long-term postoperative results of infantile esotropia and myopia

PURPOSE

To determine the short-term (6 month) and long-term (4 year) surgical results of infantile esotropia in a control group of 100 patients, as compared to a myopia (-2.0 to -5.0 diopters [D]) group of 13 patients and to a high-myopia (greater than -8.0 D) group of 14 patients.

METHOD

A retrospective chart review with selection according to inclusion criteria.

RESULTS

All 14 high-myopic patients (100%) achieved short-term unacceptable result of large-angle (greater than 20 prism diopters) deviation as compared to 29 (29%) and four (31%) of the patients in the control and myopia groups, respectively (P < 0.0001). Eighty (80%) of the patients in the control group and 10 (77%) in the myopia group achieved long-term favorable postoperative results of subnormal binocular vision, microtropia, or small-angle (less than 20 prism diopters) deviation, with no statistical differences between the two groups. In contrast, 10 (71%) of the patients in the high-myopia group achieved a final unacceptable result of large-angle deviation, as compared to 20 (20%) and three (23%) in the control and myopia groups, respectively (P < 0.0001). Persistent preoperative amblyopia was associated with a higher percentage of unfavorable surgical results and was more frequent in the high-myopia group (50%) as compared to the control group (14%) (P = 0.0004).

CONCLUSIONS

Careful attention must be directed preoperatively toward reversing amblyopia and correcting refractive errors because persistent amblyopia at the time of surgery was associated with a higher percentage of unacceptable postoperative large-angle deviation. The conventional amount of recession or resection of muscles should be increased in high-myopic cases with infantile esotropia, because less effect is produced per millimeter of recession/resection initially and, in the long-term, the constant stimulus to accommodative convergence apparently causes recurrent esotropia.

Obligatory role of the LIFG in synonym generation: evidence from PET and cortical stimulation

We report results from a patient in whom we obtained converging evidence from positron emission tomography (PET) and intraoperative stimulation mapping to support a one-way dissociation between the functional areas involved in word repetition and synonym generation. Intraoperative stimulation mapping interfered with synonym generation but did not disturb word repetition at the same left inferior frontal site at which a cerebral blood flow (CBF) increase had been observed for a synonym generation task. The results for this single subject suggest that the functional areas involved in different aspects of linguistic processing are dissociable and that specific disruption under conditions of cortical stimulation can be correlated with the brain regions identified via PET as the most active during performance of a specific task.

Sperm ultrastructure of six Australian hylid frogs from two genera (Litoria and Cyclorana): phylogenetic implications

The spermatozoa of four fossorial (Litoria alboguttata, Cyclorana brevipes, Cyclorana novaehollandiae and Cyclorana cryptotis) and two non-fossorial australian hylid frogs (Litoria aurea and Litoria moorei) together with previously examined Litoria (Hylidae: Anura) are compared. In spermatozoal ultrastructure (in particular the structure of the sperm tail) Cyclorana includes species which appear derived (apomorphic) relative to non-fossorial species of Litoria while the fossorial L. alboguttata groups with Cyclorana. All hylid species examined here are united by the bufonoid synapomorphy of a conical subacrosomal cone consisting of separate sheaves and the eubufonoid synapomorphy of a mitochondrial sheath or collar separated by a cytoplasmic canal from the centriolar region and tail. Spermatozoal symplesiomorphies for the Eubufonoidea, seen in Litoria (with the exception of L. alboguttata), are the well developed thin undulating membrane with juxta-axonemal and axial fibre. L. alboguttata, C. novaehollandiae and C. brevipes appear monophyletic in the apomorphic modification of the undulating membrane as a thick, dense structure. In L. alboguttata and C. novaehollandiae this structure retains a swelling, at the free edge, homologized with the axial rod. C. brevipes has a further apomorphy as the undulating membrane forms a parallel-sided dense structure with no separate differentiation of an axial fibre. C. cryptotis, however, retains the plesiomorphic sperm tail with a thin undulating membrane, juxta-axonemal and axial fibre. That these differences in spermatozoal ultrastructure have phylogenetic significance is endorsed by the similarity of the fertilization biology of the species examined. On the basis of sperm ultrastructure three separate lineages are discerned within Cyclorana s. lat.: 1) C. cryptotis; 2) L. alboguttata and C. novaehollandiae; and 3) C. brevipes. The evidence of sperm ultrastructure, supported by previously published molecular, morphological and karyological data, clearly places Litoria alboguttata within the genus Cyclorana.

Short tandem repeat HumACTBP2 (SE33) and HumVWA: population genetic study on a north Italian population

Allele frequencies at the short tandem repeat (STR) loci HumACTBP2 and HumVWA were determined in 118 unrelated individuals from Northern Italy (Milan area). For locus HumACTBP2 (SE33) a total of 39 alleles was observed. Furthermore, two interalleles (N18m+N19m) and one allele (> N35) were found which were not observed in a wider German population survey (n = 560). For the STR system HumVWA, 7 alleles could be detected. Both systems showed no significant deviation from Hardy-Weinberg equilibrium. A comparison of Italian and German population data revealed no significant differences for locus HumVWA, while significant differences were observed for locus HumACTBP2.

Prevalence of intestinal parasites in the human population of León, Nicaragua

Intestinal parasites appear to be prevalent in Nicaragua, which motivated a more extensive prevalence study in which socioeconomic conditions such as degree of crowding, quality of water supply, type of floor and disposal of excretion, were considered. The study was performed on 1267 stool samples from about 8% of the citizens of the city of León. The overall prevalence of intestinal pathogenic parasites among the 1267 individuals was found to be 47.2%. The prevalence of Entamoeba histolytica/dispar was 18.6% followed by Giardia (15.9%) and Ascaris (13.4%). Other helminths such as hookworms and Strongyloides sp. were found at very low rates. Giardia, in contrast to worm infections, was prevalent already in children under 5 years of age. E. histolytica/dispar increased with age and remained high. Of 595 individuals with intestinal parasites 81% were living in 'poor' conditions and in 13 clusters of households, a lower prevalence of parasites was seen in households characterised as having good socioeconomic conditions. However, several variables appear to be important in determining the prevalence of the individual intestinal protozoa and helminths encountered.

Sequence-specific epigenetic effects of the maternal somatic genome on developmental rearrangements of the zygotic genome in Paramecium primaurelia

In ciliates, the germ line genome is extensively rearranged during the development of the somatic macronucleus from a mitotic product of the zygotic nucleus. Germ line chromosomes are fragmented in specific regions, and a large number of internal sequence elements are eliminated. It was previously shown that transformation of the vegetative macronucleus of Paramecium primaurelia with a plasmid containing a subtelomeric surface antigen gene can affect the processing of the homologous germ line genomic region during development of a new macronucleus in sexual progeny of transformed clones. The gene and telomere-proximal flanking sequences are deleted from the new macronuclear genome, although the germ line genome remains wild type. Here we show that plasmids containing nonoverlapping segments of the same genomic region are able to induce similar terminal deletions; the locations of deletion end points depend on the particular sequence used. Transformation of the maternal macronucleus with a sequence internal to a macronuclear chromosome also causes the occurrence of internal deletions between short direct repeats composed of alternating thymines and adenines. The epigenetic influence of maternal macronuclear sequences on developmental rearrangements of the zygotic genome thus appears to be both sequence specific and general, suggesting that this trans-nucleus effect is mediated by pairing of homologous sequences.

Tissue distribution of amphetamine isomers in a fatal overdose

A young man (22 years old) died of a cardiorespiratory arrest a few hours following admission to the emergency department of a hospital. He was found lying seriously ill in the parking lot of a dance club. Screening of postmortem blood and urine with enzyme multiplied immunoassay (EMIT) detected only amphetamines, caffeine, and cotinine. Further screening of blood, urine, and stomach contents with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) was negative for all three matrices. Specific conditions for amphetamines were used for the gas chromatographic (GC) screening (GC-mass spectrometric [MS] and GC-nitrogen-phosphorus detection). This resulted in the preliminary identification of amphetamine in both blood and urine. Confirmation of the presence of amphetamine in all available postmortem specimens was provided by mass and infrared spectral data (GC-MS and GC-Fourier transform infrared spectrometry) after derivatization. Quantitative results and differentiation between the enantiomers of amphetamine were obtained after chiral derivatization. The calculated concentrations disclosed amphetamine ingestion as the cause of this fatality.

Tissue distribution of trichloroethylene and its metabolites in a forensic case

A fatality that was due to the ingestion of the halogenated solvent trichloroethylene is presented. The decedent was a 43-year-old male who was found dead at his home. Screening of the blood and stomach contents with the enzyme multiplied immunoassay technique and radioimmunoassay demonstrated the presence of ethanol, amphetamine-like compounds, caffeine, cotinine, and acetaminophen. These compounds were present in toxicologically irrelevant concentrations as confirmed by thin-layer chromatography, high-performance liquid chromatography, and gas chromatography (GC). The Fujiwara reaction was performed on all available matrices, and it revealed the presence of chlorinated hydrocarbons in high concentrations. A specific GC method with electron capture detection allowed the quantitation of trichloroethylene and its metabolites trichloroethanol and trichloroacetic acid in different matrices. GC with Fourier-transform infrared detection was used for the confirmation of the identity of trichloroethylene.

Cable properties of dendrites in hippocampal neurons of the rat mapped by a voltage-sensitive dye

Dendrites of pyramidal neurons from embryonic rat hippocampus are investigated in culture using a voltage-sensitive fluorescent dye. The electrical response to somatic stimulation is observed as a time-resolved map with a resolution of 0.9 microm at a time constant of 0.4 ms without signal averaging. The data are interpreted in terms of a tapering cable with Hodgkin-Huxley parametrization. The spread of short hyperpolarizing transients is damped by capacitive shunting. The invasion of an action potential is boosted by voltage-gated conductances of a low density. No irregularity is observed at a bifurcation. The passive cable parameters of internal resistance and membrane resistance at resting voltage are Ri = 300 omega cm and Rm = 40 (k)omega cm2 respectively, at a maximum sodium conductance of approximately 4.4 mS/cm2. The electrotonic length constant and the dynamic length constant at 1 kHz are 580 and 90 microm respectively. These results are compatible with electrophysiological data of dendrites in slices of adult hippocampus and with optical data of narrow processes of leech neurons in culture. The functional implications of boosting an action potential by voltage-gated channels of low density are considered.