Detection of unwanted residues of ivermectin in bovine milk by dissociation-enhanced lanthanide fluoroimmunoassay

Avermectins are frequently used to control parasitic infestations in many animal species. Previous studies have shown the long-term persistence of unwanted residues of these drugs in animal tissues and fluids. An immunoassay screening test for the detection acid quantification of ivermectin residues in bovine milk has been developed. After an extensive extraction procedure, milk samples were applied to a competitive dissociation-enhanced lanthanide fluoroimmunoassay using a monoclonal antibody against an ivermectin-transferrin conjugate, The monoclonal antibody, raised in Balb C mice, showed cross-reactivity with eprinomectin (92%), abamectin (82%) and doramectin (16%). The limit of detection of the assay (mean + 3 SD), calculated from the analysis of 17 known negative samples, was calculated as 4.6 ng/mL. Intra- and inter-assay RSDs were determined as 11.6% and 15.8%, respectively, using a negative bovine milk sample fortified with 25 ng/mL ivermectin. Six Friesian milking cows were treated with ivermectin, three with a pour-on formulation of the drug and three with an injectable solution at the manufacturer's recommended dose rate. An initial mean peak in ivermectin residue concentration was detected at day 4 (mean level = 47.5 ng/mL) and day 5 post-treatment (mean level = 26.4 ng/mL) with the injectable form and pour-on treatment, respectively. A second peak in residue concentration was observed using the DELFIA(R) procedure 28 days post-treatment in both treatment groups (23.1 ng/mL injectable and 51.9 ng/mL pour-on). These second peaks were not confirmed by HPLC and must at this Lime be considered to be false-positive results. By day 35 after treatment the mean ivermectin residue concentration of both groups fell below the limit of detection of the assay. Copyright (C) 2000 John Wiley & Sons, Ltd.

DETERMINATION OF THE CONCENTRATIONS OF THE STEROIDS ESTRADIOL, PROGESTERONE AND TESTOSTERONE IN BOVINE SERA - COMPARISON OF COMMERCIAL DISSOCIATION ENHANCED LANTHANIDE FLUORESCENCE IMMUNOASSAY KITS WITH CONVENTIONAL RADIO AND ENZYME IMMUNOASSAYS

The performance of three conventional enzyme and radioimmunoassays routinely used to detect residues of anabolic steroids in cattle sera were compared with dissociation enhanced lanthanide fluorescence immunoassay (DELFIA) kits designed for the hospital market. Slight modifications to the kit reagents were required for the analysis of bovine sera. Owing to the large sample volumes used in conventional assays, detection limits were generally better than those obtained with DELFIA kits, however, assay reproducibility was enhanced using the DELFIA technology. Comparison of sera obtained from cattle implanted with anabolic steroids revealed a good correlation between alternate methods (r(2) from 0.91 to 0.97). The DELFIA kits offer a faster method for measuring estradiol, progesterone and testosterone with adequate sensitivity and in a safer environment than that encountered using radioimmunoassays.

Structural brain abnormalities in male schizophrenics reflect fronto-temporal dissociation

Background. Many studies have separately reported abnormalities of frontal and temporal lobe structures in schizophrenia, but little is known of structural fronto-temporal associations in this condition. We investigated whether male patients with chronic schizophrenia would show abnormal patterns of correlation between regional brain volumes.

Methods. Structural magnetic resonance images of the brain in 42 patients were compared with 43 matched unaffected controls. We explored the pattern of association between regional brain volumes by correlational analyses, and non-parametrically tested for significance of between-group differences by randomization.

Results. The schizophrenics demonstrated significant volume deficits in several brain regions (left temporal lobe and hippocampus, right dorsolateral prefrontal cortex), and significant volume increases in the ventricular system (third ventricle and left temporal horn of the lateral ventricle). Controls demonstrated large positive correlations (r > 0.4) between prefrontal and temporal lobe regions. By contrast, inter-regional correlations significantly reduced in schizophrenics included those between prefrontal, anterior cingulate and temporal regions, and between posterior cingulate and hippocampus (P < 0.05). The most salient abnormality in patients was a dissociation between prefrontal and superior temporal gyrus volumes (P < 0.01).

Conclusions. These results support the existence of a relative 'fronto-temporal dissociation' in schizophrenia which we suggest may be due to lack of mutually trophic influences during frontal and temporal lobe development.

Complex trauma and intimate relationships: The impact of shame, guilt and dissociation

Background: This study examined dissociation, shame, guilt and intimate relationship difficulties in those with chronic and complex PTSD. Little is known about how these symptom clusters interplay within the complex PTSD constellation. Dissociation was examined as a principle organizing construct
within complex PTSD. In addition, the impact of shame, guilt and dissociation on relationship difficulties was explored.
Methods: Sixty five treatment-receiving adults attending a Northern Irish service for conflict-related trauma were assessed on measures of dissociation, state and trait shame, behavioral responses to shame, state and trait guilt, complex PTSD symptom severity and relationship difficulties.
Results: Ninety five percent (n=62) of participants scored above cut-off for complex PTSD. Those with clinical levels of dissociation (n=27) were significantly higher on complex PTSD symptom severity, state and trait shame, state guilt, withdrawal in response to shame and relationship preoccupation than subclinical dissociators (n=38). Dissociation and state and trait shame predicted complex PTSD. Fear of relationships was predicted by dissociation, complex PTSD and avoidance in response to shame, while complex PTSD predicted relationship anxiety and relationship depression.
Limitations: The study was limited to a relatively homogeneous sample of individuals with chronic and complex PTSD drawn from a single service.
Conclusions: Complex PTSD has significant consequences for intimate relationships, and dissociation makes an independent contribution to these difficulties. Dissociation also has an organizing effect on
complex PTSD symptoms.

Exchange-correlation energy and potential as approximate functionals of occupied and virtual Kohn-Sham orbitals: Application to dissociating H-2

The standard local density approximation and generalized gradient approximations fail to properly describe the dissociation of an electron pair bond, yielding large errors (on the order of 50 kcal/mol) at long bond distances. To remedy this failure, a self-consistent Kohn-Sham (KS) method is proposed with the exchange-correlation (xc) energy and potential depending on both occupied and virtual KS orbitals. The xc energy functional of Buijse and Baerends [Mol. Phys. 100, 401 (2002); Phys. Rev. Lett. 87, 133004 (2001)] is employed, which, based on an ansatz for the xc-hole amplitude, is able to reproduce the important dynamical and nondynamical effects of Coulomb correlation through the efficient use of virtual orbitals. Self-consistent calculations require the corresponding xc potential to be obtained, to which end the optimized effective potential (OEP) method is used within the common energy denominator approximation for the static orbital Green's function. The problem of the asymptotic divergence of the xc potential of the OEP when a finite number of virtual orbitals is used is addressed. The self-consistent calculations reproduce very well the entire H-2 potential curve, describing correctly the gradual buildup of strong left-right correlation in stretched H-2. (C) 2003 American Institute of Physics.

A Preliminary Qualitative Investigation of Voice Hearing and Its Association with Dissociation in Chronic PTSD

Following on from a quantitative study, this research used a qualitative methodology to investigate the lived experience of 3 men with chronic posttraumatic stress disorder associated with the conflict in Northern Ireland who reported auditory hallucinations. Data analysis used the Framework method. Results showed that beliefs about voices, dissociation of identity and body, and interpersonal impact were central superordinate themes associated with auditory hallucinations in posttraumatic stress disorder. Central subordinate themes included feeling a lack of controllability over voices, experiencing them as ego-dystonic, and feeling an increased sense of isolation and shame because of their presence. Results provide an in-depth analysis of participants' lived experiences and enhance understanding of previous quantitative findings.

Non-Markovian qubit dynamics induced by Coulomb crystals

We investigate the backflow of information in a system with a second-order structural phase transition, namely, a quasi-one-dimensional Coulomb crystal. Using standard Ramsey interferometry which couples a target ion (the system) to the rest of the chain (a phononic environment), we study the non-Markovian character of the resulting open system dynamics. We study two different time scales and show that the backflow of information pinpoints both the phase transition and different dynamical features of the chain as it approaches criticality. We also establish an exact link between the backflow of information and the Ramsey fringe visibility.