Metabolic abnormalities in developmental dyslexia detected by 1H magnetic resonance spectroscopy

BACKGROUND: Neurological and physiological deficits have been reported in the brain in developmental dyslexia. The temporoparietal cortex has been directly implicated in dyslexic dysfunction, and substantial indirect evidence suggests that the cerebellum is also implicated. We wanted to find out whether the neurological and physiological deficits manifested as biochemical changes in the brain. METHODS: We obtained localised proton magnetic resonance spectra bilaterally from the temporo-parietal cortex and cerebellum of 14 well-defined dyslexic men and 15 control men of similar age. FINDINGS: We found biochemical differences between dyslexic men and controls in the left temporo-parietal lobe (ratio of choline-containing compounds [Cho] to N-acetylaspartate [NA] p< or =0.01) and right cerebellum (Cho/NA, p< or = 0.01; creatine [Cre] to NA p< or =0.05; (not significant). We found lateral biochemical differences in dyslexic men in both these brain regions (Cho/NA in temporo-parietal lobe, left vs right, p< or =0.01; Cre/NA in cerebellum, left vs right, p< or =0.001). We found no such lateral differences in controls. There was no significant relation between the degree of contralateral chemical difference and handedness in dyslexic or control men. INTERPRETATION: We suggest that the observed differences reflect changes in cell density in the temporo-parietal lobe in developmental dyslexia and that the altered cerebral structural symmetry in dyslexia is associated with abnormal development of cells or intracellular connections or both. The cerebellum is biochemically asymmetric in dyslexic men, indicating altered development of this organ. These differences provide direct evidence of the involvement of the cerebellum in dyslexic dysfunction.     

Rapid detection of different RNA respiratory virus species by multiplex RT-PCR: application to clinical specimens

Inconsistent findings from recent mortality studies of workers exposed to magnetic fields have led to calls for more detailed understanding of exposure distributions and metrics in various industries. The authors undertook personal monitoring at an automobile transmission plant to (a) learn if magnetic field exposure differences were present, (b) make assignments for a brain cancer study, and (c) compare two exposure indices. A wide range of average exposures occurred (i.e., 0.016-4.6 microtesla). Within-day variability was also large, and it reached 4 orders of magnitude for some workers. Unexpectedly, demagnetizers were found among the strong sources that contributed to elevated exposures. The authors used conventional summary measures to assign job groups to exposure categories, and they used a new index of exposure irregularity to make alternative assignments. These new assignments appeared to differ from the original ones with respect to work time in each exposure group (i.e., 54% of the work time fell into different exposure categories).     

Absorption of simple nutrients from the in vivo neurally isolated canine jejunum and ileum

BACKGROUND: The effects of intestinal transplantation on enteric absorptive function are not well understood. Our aim was to determine the effects of in situ isolation of the jejunoileum, a large animal model of jejunoileal autotransplantation, on absorption of simple nutrients from the jejunum and ileum separately. METHODS: Four groups of dogs were prepared with modified Thiry-Vella loops: group 1, neurally intact jejunum; group 2, neurally isolated jejunum; group 3, neurally intact ileum; and group 4, neurally isolated ileum. Intestinal loops were perfused with five different isosmolar solutions of NaCl alone, 30 mmol/L glucose, 2.5 mmol/L glycine, 2.5 mmol/L phenylalanine, and 5 mmol/L oleic acid at 1 to 2 weeks and 8 to 9 weeks after operation. RESULTS: Net absorption of water and electrolytes, glucose, glycine, phenylalanine, and oleic acid were not different statistically between neurally intact and neurally isolated intestinal loops at either time point. Ileal loops absorbed more than jejunal loops. CONCLUSIONS: Absorption of simple nutrients from the canine jejunum and ileum is not altered by this model of intestinal autotransplantation. These observations suggest that the extrinsic denervation that accompanies intestinal transplantation does not affect the transport systems for glucose, glycine, phenylalanine, or oleic acid.     

An evaluation of the Ektachem serum lithium method and comparison with flame emission spectrometry

We evaluated the performance of a new colorimetric method in dry chemistry for serum lithium (Li) assay using an Ektachem E500 analyser. Imprecision results were acceptable and the linearity was verified for concentrations within the range of 0.2-3.9 mmol l-1, i.e. y(measured) = 1.02x(calculated) + 0.07, r = 0.99. The Ektachem Li assay was unaffected by potassium (K), calcium (Ca) and magnesium (Mg) at all concentrations tested. Significant interference was caused by sodium (Na) and haemoglobin. Statistically and clinically significant interference was caused by high concentrations of Na (213 mmol l-1) with a bias of 0.20 mmol l-1 (p = 0.02) and by high levels of haemoglobin (280 mumol l-1) with a bias of 0.20 mmol l-1 (p = 0.01). Comparison of serum Li results from 80 patient samples assayed using the Ektachem method with those obtained using the IL943, a flame atomic emission spectrometry (FAES)-based method, gave a regression line equation: Ektachem = 0.95xFAES + 0.13, r = 0.96. The data revealed a mean difference of 0.10 mmol l-1 between the Ektachem and FAES results that was statistically significant (p = 0.01), but clinically negligible. We conclude that the Kodak method provides reliable Li serum results and represents a valid alternative to the FAES method.     

Blood cell transplantation: report from an International Consensus Meeting

An International Consensus Meeting on blood cell transplantation took place in Heemskerk, The Netherlands on 27-29 June 1994. The term 'blood cell transplantation' was preferred to peripheral blood stem cell transplantation. The following issues were addressed: stem cell assessment and ex vivo expansion, techniques for stem cell mobilization, applications of blood cell transplantation, malignant cell contamination and allogeneic blood cell transplantation.     

Phenylalanine and tyrosine metabolism in neonates receiving parenteral nutrition differing in pattern of amino acids

Tyrosine is considered to be an indispensable dietary amino acid in the neonate, yet achieving adequate parenteral tyrosine intake is difficult due to its poor solubility. Increasing the supply of phenylalanine is the most common means of compensating for low tyrosine levels. Unfortunately, plasma phenylalanine concentrations are sometimes elevated in infants receiving high phenylalanine intake. This led us to study the phenylalanine and tyrosine metabolism in 16 neonates randomized to receive total parenteral nutrition with either a high or a moderate phenylalanine-containing amino acid solution. A primed, 24-h continuous stable isotope infusion of L-[1-13C]phenylalanine and L-[3,3-2H2]tyrosine was given to enable the measurement of phenylalanine and tyrosine kinetics. Results demonstrated that 1) phenylalanine hydroxylation was significantly greater in infants receiving high phenylalanine, 2) phenylalanine oxidation and percent dose oxidized was also significantly greater in infants receiving high phenylalanine, 3) apparent phenylalanine retention was greater in neonates receiving high phenylalanine, and 4) alternate catabolites of phenylalanine and tyrosine metabolism were significantly greater in infants receiving high phenylalanine compared with moderate phenylalanine. We conclude that neonates respond to increased parenteral phenylalanine intake by increasing their hydroxylation and oxidation rates. The greater oxidation of phenylalanine in infants receiving high phenylalanine in conjunction with the urinary excretion of alternate catabolites of phenylalanine and tyrosine suggests that the high phenylalanine intake may be in excess of needs. However, the lower apparent phenylalanine retention observed in infants receiving moderate phenylalanine suggests that the total aromatic amino acid level of moderate phenylalanine may be deficient for neonatal needs.     

IL-10 regulates thrombus-induced vein wall inflammation and thrombosis

Vein wall inflammation associated with venous thrombosis is mediated by an imbalance in proinflammatory as compared with antiinflammatory molecules. We hypothesize that IL-10 is an important antiinflammatory cytokine that influences vein wall inflammation and thrombus propagation during venous thrombosis. To test this hypothesis a model of inferior vena caval thrombosis was used. Studies were performed at sacrifice 2 days after thrombus induction and included leukocyte morphometrics, myeloperoxidase activity, vein wall permeability, thrombus weight, and IL-10 ELISA analysis from the vein wall. IL-10 was elevated in the vein wall during venous thrombosis. Neutralization of IL-10 increased inflammation, while supplementation with rIL-10 demonstrated a dose- and time-dependent decrease in inflammation. Interestingly, a low 2.5-microg rIL-10 dose given at time of initiation of thrombosis most significantly decreased inflammation. Thrombus weight was importantly diminished by reconstitution of IL-10. These studies support an important role for IL-10 in the regulation of thrombus-associated inflammation and thrombosis and suggest that IL-10 could be used as a therapeutic agent in the treatment of venous thrombosis.