In vitro 2,3,7,8-tetrachlorodibenzo-p-dioxin interference with the anterior pituitary hormone adrenocorticortropin

Pharmacological effects of acute treatment with venlafaxine (VEN), a clinically active antidepressant [a noradrenaline (NA) and 5-hydroxytryptamine (5-HT) reuptake inhibitor without any affinity for neurotransmitter receptors] were studied in mice and rats. VEN inhibited the reserpine- or apomorphine-induced hypothermia and enhanced the L-5-HTP-induced head twitches in mice. It reduced the immobility time in Porsolt's test in mice and rats, but either did not change the locomotor activity (mice) or decreased it (rats). VEN reduced the locomotor hyperactivity induced by amphetamine (AMP), apomorphine (APO) and quinpirole (QUI), as well as the APO-induced stereotypy; the stereotypy induced by AMP in rats was prolonged. VEN neither changed the clonidine-induced aggressiveness in mice nor the behavioral syndrome induced by oxotremorine in rats. The obtained results indicate that VEN, given acutely, shows a pharmacological profile similar to that of tricyclic NA and 5-HT reuptake inhibitors. In contrast to the antidepressants mentioned above, VEN does not exhibit an alpha 1-adrenolytic or a cholinolytic activity (in vivo tests).     

The effect of varying stimulus rate and duration on brain activity during reading

The effect of the presentation rate and exposure duration of visually presented words on brain activity was investigated using positron emission tomography. Subjects either read aloud or silently mouthed the names of words. In regions associated with early visual analysis, activity increased with both rate and duration; in regions associated with response generation, activity increased with increasing rate but was unaffected by duration; and in regions associated with word recognition, activity decreased with increasing duration. The variable responses of different brain regions illustrate the functional segregation of these regions. Of particular interest was the dissociation between activity in the posterior fusiform gyri and that in the medial lingual gyrus--in the former, activity increased with rate and duration but the latter was unaffected by either variable. This finding suggests that word processing in the lingual gyrus during reading is distinct from that in the posterior fusiform gyri. A further observation was that during reading aloud, when subjects can hear the sound of their own voice, the response in the primary auditory cortices increased with stimulus rate, demonstrating that subjects process the sound of their own voice in a qualitatively similar way to words spoken by another.     

Prospects for insulin delivery by ex-vivo somatic cell gene therapy

The principle of insulin delivery by ex-vivo somatic cell gene therapy involves the removal of non-B-cell somatic cells (e.g. fibroblasts) from a diabetic patient, and genetically altering them in vitro to produce and secrete insulin. The cells can be grown in culture and returned to the donor as a source of insulin replacement. Cells modified in this way could be evaluated before implantation, and reserve stocks could be cryopreserved. By using the patient's own cells, the procedure should obviate the need for immunosuppression and overcome the problem of tissue supply, while avoiding a recurrence of cell destruction. Ex-vivo somatic cell gene therapy requires an accessible and robust cell type that is amenable to multiple transfections and subject to controlled proliferation. Special problems associated with the use of non-B-cell somatic cells include the processing of proinsulin to insulin, and the conferment of sensitivity to glucose-stimulated proinsulin biosynthesis and regulated insulin release. Preliminary studies using fibroblasts, pituitary cells, kidney (COS) cells and ovarian (CHO) cells suggest that these challenges could be met, and that ex-vivo somatic cell gene therapy offers a feasible approach to insulin replacement therapy.     

The membrane affinities of the aliphatic amino acid side chains in an alpha-helical context are independent of membrane immersion depth

Understanding, predicting, and designing the binding of peptides and proteins to bilayers require quantifying the intrinsic propensities of individual amino acid residues to bind membranes as a function of structural context and bilayer depth. A host-guest study was performed using the peptide host named helix5 in order to determine the membrane affinities of the aliphatic side chains both in an alpha-helical context and as a function of bilayer depth. Use of the alpha-helical host with a constrained geometry allowed the placement of guest sites at three different depths in bilayers and minimized secondary structural changes due to guest substitutions. Circular dichroism and electron paramagnetic resonance (EPR) were used to characterize the aqueous and bilayer-bound structures of the peptide variants. EPR was also used to measure the bilayer-water partition constants of the peptide variants, and the Delta DeltaGtr values (relative to Gly) of the aliphatic amino acid side chains were subsequently calculated. Surprisingly, the DeltaDeltaGtr values did not significantly vary as a function of the guest site depth in bilayers. In addition, the Delta DeltaGtr values determined in an alpha-helical context are reduced to approximately two-thirds of Delta DeltaGtr values determined in other studies for the bilayer-water and octanol-water partitioning of amino acid side chains in extended and unstructured hosts. Both the relative reduction in Delta DeltaGtr values in the context of an alpha-helical host and the invariance of Delta DeltaGtr values with respect to bilayer depth are consistent with the membrane affinities of the aliphatic residues being largely determined by the classical hydrophobic effect.     

Validation of highly polymorphic fluorescent multiplex short tandem repeat systems using two generations of DNA sequencers

Validation studies are a crucial requirement before implementation of new genetic typing systems for clinical diagnostics or forensic identity. Two different fluorescence-based multiplex DNA profiling systems composed of amelogenin, HumD21S11 and HumFGA (referred to as multiplex 1A), and HumD3S1358, HumD21S11 and HumFGA (multiplex 1B) have been evaluated for use in forensic identification using the Applied Biosystems Model 373A and Prism 377 DNA Sequencers, respectively. Experiments were aimed at defining the limit of target DNA required for reliable profiling, the level of degradation that would still permit amplification of the short tandem repeat (STR) loci examined, and the robustness of each locus in the multiplexes after samples were exposed to environmental insults. In addition, the specificity of the multiplexes was demonstrated using nonhuman DNAs. Forensically relevant samples such as cigarette butts, chewing gum, fingernails and envelope flaps were processed using both an organic extraction procedure and a QIAamp protocol. DNAs and resultant multiplex STR profiles were compared. The validation of the triplex STR systems was extended to include over 140 nonprobative casework specimens and was followed with a close monitoring of initial casework (over 300 exhibits). Our results document the robustness of these multiplex STR profiling systems which, when combined with other multiplex systems, could provide a power of discrimination of approximately 0.9999.