Amphetamines in hair by enzyme-linked immunosorbent assay

Human hair was collected from the occipital crown region of the head from several subjects; these hair samples were presumptively positive for amphetamines by a previously evaluated immunoassay. Hair was washed briefly with methanol to remove external contamination, then extracted with hot methanol for 2 h to recover the drugs. The extracts were evaporated to dryness, reconstituted in buffer, and analyzed using a new enzyme-linked immunosorbent assay (ELISA) technique adapted for the detection of amphetamines in hair. Gas chromatography-mass spectrometry was used as the reference technique. Cross-reactivity of several related compounds was evaluated by equating the inverse of the ligand concentration at 50% antibody binding to the affinity constant for each compound. The ratio of a compound's affinity constant to that for d-methamphetamine was used to derive percent crossreactivity. These experiments yielded values of 30.8% for d-amphetamine, 7.4% for I-methamphetamine, 4.3% for phentermine, 2.9% for I-amphetamine, and <1% for ephedrine, methylenedioxyamphetamine, and methylenedioxymethamphetamine. Cross-reactivity of unrelated compounds was found to be non-existent. The optimum cutoff concentration was determined by receiver operating characteristic curve analysis to be 300 pg/mg and the observed limit of detection was 60 pg/mg. Intra-assay precision at 300 pg/mg was 3.3% (coefficient of variation, CV), and the interassay CV was 10.5%. The sensitivity and specificity of the method were 83% and 92%, respectively.     

Hydroxyapatite fiber reinforced poly(alpha-hydroxy ester) foams for bone regeneration

A process has been developed to manufacture biodegradable composite foams of poly(DL-lactic-co-glycolic acid) (PLGA) and hydroxyapatite short fibers for use in bone regeneration. The processing technique allows the manufacture of three-dimensional foam scaffolds and involves the formation of a composite material consisting of a porogen material (either gelatin microspheres or salt particles) and hydroxyapatite short fibers embedded in a PLGA matrix. After the porogen is leached out, an open-cell composite foam remains which has a pore size and morphology defined by the porogen. By changing the weight fraction of the leachable component it was possible to produce composite foams with controlled porosities ranging from 0.47 +/- 0.02 to 0.85 +/- 0.01 (n = 3). Up to a polymer:fiber ratio of 7:6, short hydroxyapatite fibers served to reinforce low-porosity PLGA foams manufactured using gelatin microspheres as a porogen. Foams with a compressive yield strength up to 2.82 +/- 0.63 MPa (n = 3) and a porosity of 0.47 +/- 0.02 (n = 3) were manufactured using a polymer:fiber weight ratio of 7:6. In contrast, high-porosity composite foams (up to 0.81 +/- 0.02, n = 3) suitable for cell seeding were not reinforced by the introduction of increasing quantities of hydroxyapatite short fibers. We were therefore able to manufacture high-porosity foams which may be seeded with cells but which have minimal compressive yield strength, or low porosity foams with enhanced osteoconductivity and compressive yield strength.     

Gi-mediated stimulation of type II adenylyl cyclase is augmented by Gq-coupled receptor activation and phorbol ester treatment

Synergism between Gs- and Gi- or Gq-dependent signaling pathways has been demonstrated in the stimulation of type II adenylyl cyclase (AC-II). Provision of activated alpha s is known to allow numerous Gi-coupled receptors to stimulate AC-II and to potentiate the responses to Gq-coupled receptors. To explore possible interactions between Gi- and Gq-coupled receptors that are independent of alpha s, the activity of AC-II was determined after the activation of Gi- and Gq-regulated pathways. Human embryonic kidney 293 cells were transiently cotransfected with cDNAs encoding AC-II and various G-protein-coupled receptors. Agonist-bound Gi-coupled receptors (including the formyl peptide, dopamine-D2, and delta-opioid receptors) stimulated AC-II activity in the absence of activated alpha s, provided that the cells were treated with 100 nM phorbol 12-myristate 13-acetate. Activation of protein kinase C (PKC) thus appears to relieve the requirement for the presence of activated alpha s. Stimulation of PKC via Gq-coupled receptors also allowed Gi-coupled receptors to activate AC-II. Coexpression of the m1 muscarinic receptor with the dopamine-D2 receptor permitted dopamine to stimulate AC-II in the presence of carbachol. The phorbol ester-permissive and alpha s-independent stimulation was mediated by G-protein beta gamma subunits because it was blocked by the beta gamma scavengers alpha t and beta-adrenergic receptor kinase. These results show that AC-II can efficiently integrate signals generated by Gq- and Gi-coupled receptors via a mechanism that is independent of Gs.     

Repair of central upper lip (philtral) surgical defects with island pedicle flaps

BACKGROUND: Surgical defects of the central upper lip (philtrum) are a particularly difficult area to achieve satisfactory cosmetic and functional repair. Reconstruction of the central upper lip has been accomplished primarily through the use of side-to-side closure, bilateral advancement or rotation flap, and full-thickness graft. Repair may be complicated by distortion of the vermilion border, obliteration of the normal contour of the philtrum, eclabium, and trapdooring of the flap. OBJECTIVE: We review the options for reconstruction of this area and describe our experience using an island pedicle flap to complete reconstruction. METHODS: Four patients presented with basal cell carcinomas of the mid upper lip (philtrum). Tumors were cleared by Mohs micrographic surgery. Reconstruction was achieved by island pedicle flaps utilizing donor tissue from the superior philtrum. RESULTS: The patients had excellent cosmetic results with minimal distortion of the vermilion border or obliteration of the philtrum or philtral ridges. Scars healed in a nearly imperceptible fashion, keeping within one cosmetic unit (the philtrum) without extending along the vermilion border as seen in bilateral advancement or rotation flaps. CONCLUSIONS: Island pedicle flaps may be an effective cosmetic and functional repair of selected surgical defects of the central upper lip involving the philtrum.     

Morphological and molecular characterization of Giardia isolated from the straw-necked ibis (Threskiornis spinicollis) in Western Australia

Following the first report of avian Giardia infection in Australia, isolates of the parasite recovered from naturally infected straw-necked ibis (Theskiornis spinicollis) were characterized using median body morphology, scanning electron microscopy, multilocus enzyme electrophoresis, random amplified polymorphic DNA (RAPD), and small subunit ribosomal RNA (SSU-rRNA) analyses. Results were compared with Giardia from other birds and mammals, and the extent of genetic diversity between a range of ibis isolates collected in Western Australia was determined. The ibis isolates of Giardia were genetically relatively homogeneous, which is in contrast to the extensive genetic heterogeneity often displayed by mammalian Giardia isolates. Morphologically, Giardia from ibis were similar to Giardia ardeae although they differed genetically and by the fact that the ibis isolates could not be established in in vitro culture. Sequence data of the DNA coding for the SSU-rRNA found a 96% homology between the ibis isolates from Western Australia and G. ardeae, suggesting that they represent distinct strains of the same species. In contrast, the ibis isolates were genetically and morphologically very different than Giardia duodenalis and Giardia muris from mammals.     

Vincristine disturbs spontaneous firing of the afferent nerve fibre in ampullary electroreceptor organs

Ampullary electroreceptor organs of the catfish were apically exposed to 0.3 mM vincristine in order to investigate the part played by the microtubular system in stimulus transduction. The main effects were repetitive firing of the afferent fibre, a reduction of the mean spontaneous activity and a reduction of the spike amplitude two to four days after exposure to vincristine. The mean sensitivity was less susceptible to vincristine than the spontaneous activity. Since the shape of the frequency curves remained unchanged and similar effects as described above were also observed after denervation, we conclude that vincristine most likely does not affect electroreceptor cell functioning, but causes degeneration of the afferent fibre.