Acute alcohol blocks neurosteroid modulation of synaptic transmission and long-term potentiation in the rat hippocampal slice

Effects of ethanol (22 mM) on the modulation of synaptic transmission and long-term potentiation (LTP) by the neurosteroid dehydroepiandrosterone sulfate (DHEAS; 10 microM) was examined in the in vitro rat hippocampal slice preparation. The synaptic responses were elicited by Schaffer collateral stimulation and recorded extracellularly in the somatic and dendritic regions of CA1 pyramidal neurons. LTP induction produced an increase (approximately 55% to 75%) in the amplitude of synaptic responses in ethanol and ethanol plus DHEAS (ethanol/DHEAS) treated slices. These increases were significantly smaller than the approximately 130% increase observed previously in slices treated with DHEAS, but were not significantly different from the approximately 82% increase observed in control slices. These results indicate that an ethanol/DHEAS interaction prevents the enhancement of LTP normally observed with DHEAS treatment of hippocampal slices. An ethanol/DHEAS interaction also altered DHEAS's effects on individual synaptic components of the synaptic response to Schaffer collateral stimulation. Ethanol applied before but not after DHEAS prevented DHEAS's enhancement of the NMDA receptor-mediated synaptic component. DHEAS's depression of the GABAA receptor-mediated synaptic component was also blocked by ethanol. Ethanol or DHEAS individually had no effect on the AMPA receptor-mediated synaptic component, but application of ethanol after DHEAS resulted in a small enhancement of this synaptic component, an effect that was not observed if ethanol was applied before DHEAS. These results show that ethanol and DHEAS interact, altering DHEAS's effects on synaptic transmission and LTP in the hippocampus. Such an interaction may be involved in ethanol's actions on the CNS and raises the possibility that ethanol and DHEAS may act via a common site or pathway.     

A review of the significance of animal food products as potential pathways of human exposures to dioxins

The polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are groups of compounds with similar chemical and toxicological properties. Carcinogenicity was considered the most serious toxic end point when setting previous regulatory policies, but recent concerns have focused on the possible endocrine-disrupting activities of the dioxins. Toxicity is related to the 2,3,7,8 pattern of chlorine substitution, a pattern that also leads to chemical and metabolic stability. Dioxins are practically insoluble in water and concentrate in lipids of biological systems, leading to low background concentrations in fat of the general human population. Major environmental sources of dioxins are emissions from industrial chlorination processes and combustion of materials containing chlorine. Inhalation and water have been ruled out as significant exposure pathways, which suggests that food is the primary source. Pathways of entry into food chains are atmospheric transport of emissions and their subsequent deposition on plants, soils, and water. The major food sources seem to be fat-containing animal products and some seafoods. This conclusion is based on evaluations of potential environmental pathways involving dioxins and related compounds. Generally, dioxins and other lipophilic compounds are not taken up and translocated by plants, so residues in foods and feeds derived from seeds should be negligible. Animals on high-roughage diets, or those that ingest contaminated soil, are the most likely to accumulate dioxin residues from the environment. The conclusion that animal products are a major source of human exposure requires verification by appropriate food sampling programs and animal metabolism studies. If it is desirable to reduce human exposure to dioxins via the food supply, reduction of sources would be a more effective strategy than changing agricultural practices and food consumption patterns.     

Computer-assisted measurement of lumbar spine radiographs

RATIONALE AND OBJECTIVES: The authors evaluated a method for obtaining reproducible, reliable measurements from standard lumbar spine radiographs for determining the degree of spondylolisthesis, vertebral body height, intervertebral disk space height, disk space angle, and degree of vertebral body wedging. MATERIALS AND METHODS: Four to six easily defined points were identified on each vertebral body on anteroposterior and lateral plain radiographs of the lumbosacral spine of patients. From these points, the degree of spondylolisthesis, the vertebral body height, the intervertebral disk space height, the disk space angle, and the degree of vertebral body wedging were easily calculated by using well-known geometric relationships. This method requires the use of a personal computer and a standard spreadsheet program but does not require the use of any other specialized radiographic equipment, computer hardware, or custom software. RESULTS: Calculations of intra- and interobserver variability for the measurement of spondylolisthesis, disk space height, disk space angle, and vertebral body height measurement showed that the technique is extremely reproducible. CONCLUSION: This technique may prove useful in the prospective evaluation of potential candidates for lumbar spinal stenosis surgery.     

Potent bifunctional anticoagulants: Kunitz domain-tissue factor fusion proteins

A strategy to design potent antagonists of human coagulation factor VIIa (FVIIa) by linking two proteins that independently inhibit activity and bind at separate, nonoverlapping sites is presented. A bifunctional inhibitor (KDTF5), comprising a Kunitz-type domain engineered to inhibit the FVIIa active site and a soluble tissue factor (TF) variant that is defective as a cofactor for factor X (FX) activation, was developed from structure-based modeling of a ternary FVIIa-Kunitz domain-TF complex. KDTF5 inhibited FVIIa-dependent FX activation with a Ki* of 235 +/- 45 pM, a 193-fold and 398-fold increase in potency compared to the TF variant and Kunitz domain individually. Similarly, KDTF5 was a more potent anticoagulant in vitro compared to either inhibitory domain alone. The results demonstrate the harnessing of a macromolecular chelate effect by fusing two inhibitory ligands that bind a target at spatially distinct sites.     

In situ interleukin 5 gene expression in pediatric Crohn's disease

BACKGROUND: Eosinophils contribute to the intestinal inflammatory infiltrate in Crohn's disease (CD). Eosinophilic infiltration occurs early in Crohn's recurrences, and a release of eosinophil cationic proteins has been observed in active CD. The proliferation, differentiation, and activation of eosinophils are highly dependent on the cytokine interleukin 5 (IL5). In the present study, we used in situ hybridization (ISH) to investigate the expression of the IL5 gene in intestinal specimens from patients with CD. METHODS: We studied 14 intestinal samples from eight children who had undergone ileocolectomy for advanced CD. The samples were examined for the intensity of the inflammatory infiltrate. Normal pediatric intestine specimens served as controls. In situ hybridization was performed on frozen tissue using radiolabeled IL5 mRNA probes. RESULTS: Positive signal with the IL5 antisense probe was observed within numerous cells infiltrating the specimens involved with CD. The number of IL5-expressing cells correlated with the histological grade of inflammation. Most of the labeled cells were eosinophils, characterized by their bilobed nuclei. Rare IL5-positive cells were detected in the control tissues. No positive signal was obtained with the IL5 sense probe. CONCLUSION: These results suggest that IL5 can be produced by eosinophils at the sites of inflammation in active CD and could be involved in the immune response by activating eosinophils, at least in part through an autocrine pathway, and perhaps by interacting with B and T cells.     

Magnetoencephalographic evidence for non-geniculostriate visual input to human cortical area V5

The aim of this study was to establish whether there is non-geniculostriate input to the extrastriate motion-sensitive area V5 in humans. Responses were measured with a SQUID neuro-magnetometer to motion stimuli presented within the blind hemifield of GY, a well-documented subject with a complete absence of the left primary visual cortical area V1. The motion stimulus was a 0.5c/deg, rapidly drifting (16Hz) achromatic sinusoidal grating. With this stimulus, the magnetic responses recorded over the temporo-parieto-occipital region in normals are well modelled by localized current sources in areas V1 and V5 (Anderson, S. J. et al., Proceedings of the Royal Society, London, Series B, 1996, 263, 423-431). As a control, evoked responses were measured to a 1.0 c/deg, stationary, photometrically isoluminant red/green sinusoidal grating. With the chromatic stimulus, the principal component of the magnetic responses recorded over the occipital pole in normals is well modelled by a current source in area V1 (Fylan, F. et al., Investigative Ophthalmology and Visual Science, 1995, 36, s1053). Both stimuli subtended 4 deg vertically by 6 deg horizontally, positioned such that the stimulus extended beyond the area of macular sparing into the lower field quadrant of the blind (or sighted) hemifield. Chromatic stimuli failed to evoked responses from GY's blind (contralateral) hemifield, consistent with there being no V1 activity in his left cortical hemisphere. However, motion stimuli did evoke responses from GY's blind hemifield, originating from a location consistent with activity in area V5. We further observed that both colour and motion stimuli evoked responses from GY's sighted (ipsilateral) hemifield. We conclude that there is non-geniculostriate input to extrastriate motion-sensitive areas in the human visual system, and that this pathway subserves the residual visual sensitivity to motion in the blind hemifield that has been demonstrated psychophysically in observer GY.