Phonological disorders in children: changes in phonological process use during treatment

Unintelligible speech in childhood is often characterised by the use of unusual or deviant (i.e. non-developmental) phonological processes, e.g. initial consonant deletion. These processes are reported to appear at speech onset and to undergo little spontaneous change during the preschool years. The study reported here documents the changes that occurred in the phonological systems of seven phonologically disordered children during remediation that targeted unusual phonological processes. Qualitative changes in phonological process use were observed for all children. Six of the children made quantitative improvement in terms of the percentage consonants produced correctly in spontaneous speech. Individual differences in phonological learning strategy use are described.     

Ultrasensitive analysis of the intestinal absorption and compartmentalization of aluminium in uraemic rats: a 26Al tracer study employing accelerator mass spectrometry

BACKGROUND: Developments in accelerator mass spectrometry (AMS) now permit the determination of femtogram amounts of 26Al in blood and in various tissues with good precision and free of external contamination. METHODS: In the present study we used trace quantities of 26Al to investigate the intestinal absorption and compartmentalization of aluminium in rats with renal failure (Nx, 5/6 nephrectomy) and in pair- fed controls (C). Single oral doses of 20 ng 26Al were administered to six animals in each group and, subsequently, 24-h post-load 26Al was analysed in serum, urine, bone, liver, and spleen by means of AMS. RESULTS: Serum concentrations of 26Al were significantly lower in uraemic rats compared to controls, whereas urinary excretion was comparable (Nx, 7.11 +/- 5.78 pg/day vs C, 9.46 +/- 6.10 pg/day), suggesting a higher fraction of ultrafiltrable serum 26Al in uraemia. The target tissues of cellular transferrin-mediated 26Al uptake, liver and spleen, tended to show a larger degree of aluminium accumulation in controls (0.26 +/- 0.31 pg/g vs Nx, 0.14 +/- 0.10 pg/g and 0.37 +/- 0.27 pg/g vs Nx, 0.25 +/- 0.27 pg/g respectively). In contrast, in bone, a site of extracellular aluminium deposition, 26Al concentrations were more elevated in uraemia (1.22 +/- 0.59 pg/g vs C: 0.68 +/- 0.30 pg/g). Estimated total 26Al accumulation in all measured target tissues was significantly higher in uraemic rats (28.15 +/- 9.90 pg vs C: 17.03 +/- 7.03 pg) and total recovery of 26Al from tissue and urine was 26.58 +/- 6.74 pg in controls and 35.75 +/- 7.03 pg in uraemic animals, suggesting a fractional absorption of 0.133% and 0.175% respectively. CONCLUSIONS: Our data suggest that fractional absorption from a dietary level dose of 26Al is about 0.13%. Compartmentalization occurs in transferrin-dependent target tissues such as liver and spleen; however, in quantitative terms extracellular deposition in bone is more important. Uraemia has a significant effect on the intestinal absorption and compartmentalization of aluminium. It enhances fractional absorption and increases subsequent extracellular deposition of aluminium in bone. However, at the same time uraemia does not increase transferrin-dependent cellular accumulation of aluminium in liver and spleen.      

Reversible Adsorption of Soluble Hexameric Insulin onto the Surface of Insulin Crystals Cocrystallized with Protamine: An Electrostatic Interaction

Mixing pharmaceutical preparations of soluble neutral regular insulin solution (NRI) and neutral protamine Hagedorn (NPH) crystalline insulin suspension leads to a reduction in the measurable amount of soluble insulin in the formulation supernatant. However in spite of the loss in soluble insulin, the time-actions of these components have been shown, in clinical trials, to be unaffected. The interaction between these different physical forms of insulin has been studied using reversed-phase HPLC, isothermal titrating calorimetry, and Doppler electrophoretic light scattering analysis. Sorbent surface and solution perturbation studies revealed that the NRI adsorbs to the surface of the NPH crystal with an equilibrium constant ranging from 10⁴ M^–1 to 10⁷ M^–!, depending on the protamine concentration, pH, ionic strength, and temperature. This adsorption behavior suggests that the binding is mediated by electrostatic interactions arising between the positively-charged NPH crystal and the negatively-charged NRI hexamer. Doppler electrophoretic light scattering results, used to probe the pH-dependent surface charge of NPH and soluble insulin hexamer, support the conclusion that electrostatic interactions mediate the adsorption process. Adsorption studies under physiological conditions indicate that the elevated temperature and ionic strength, in a subcutaneous depot, are sufficient to lead to the dissociation of the NRI/NPH complex that exists in these NPH mixture formulations.     

Enhancement of performance by methyl β-carboline-3-carboxylate, in learning and memory tasks

Benzodiazepines are known to induce a profound anterograde amnesia in man. In this report, it is shown that methyl β-carboline-3-carboxylate (β-CCM), an inverse agonist of the benzodiazepine receptor, has the opposite effect; it enhances performance in learning and memory tasks. Three different learning models were used: habituation to a new environment and passive avoidance in mice and imprinting in chicks. The opposite effects of both β-CCM and the benzodiazepine diazepam were blocked by administration of the benzodiazepine receptor antagonist Ro 15-1788, provicling evidence that the benzodiazepine receptor is involved in these effects.