Two-tiered DNA-based diagnosis of transthyretin amyloidosis reveals two novel point mutations

We analyzed 11 consecutive unrelated cases of polyneuropathy due to transthyretin amyloidosis. Direct sequencing of the promoter region, exons, and splice junctions revealed that each patient was heterozygous for a mutation: six patients had valine 30 substituted by methionine (V30----M; Portuguese-Japanese type), one had threonine 60 substituted by alanine (T60----A; Appalachian type), and two had serine 77 substituted by tyrosine (S77----Y; Illinois type). In addition, two patients had previously undescribed mutation: phenylalanine 33 substituted by leucine (F33----L) and phenylalanine 64 substituted by leucine (F64----L). From present information, the probands of these novel mutations do not exhibit any pathology that clearly distinguishes them from individuals with the other mutations. The mutations extend the range of mutations associated with amyloidotic polyneuropathy. In our 11 patients, the different mutations did not seem to correlate with distinct clinical phenotypes. We developed PASA assays (PCR amplification of specific alleles) for each of the five mutations. PASA can be used by any diagnostic laboratory that can perform PCR to rapidly detect any of the known mutations. The minority of samples with an undescribed mutation can be sent to a specialty laboratory for delineation of the mutation by direct genomic sequencing. The presently described combination of methods may have widespread utility in the diagnosis of genetic disease.     

Great Safety Performance: an improvement process using leading indicators.

The Great Safety Performance model uses leading indicators to drive injury prevention and provides a process to improve a company's safety outcomes by maximizing the conditions for safety within the workplace. The model asserts that leaders and workers need to jointly create conditions whereby everyone will know what to do, be able to do it, be equipped to do it, want to do it, and experience interactions that support safe performance in their job duties. These factors are referred to as the conditions for great performance. The Great Safety Performance model can serve as a vehicle to quantify, document, and demonstrate the efforts a company invests to create a safe workplace with safe work practices. By using the Great Safety Performance model, organizations can design and implement a variety of high leverage improvement initiatives specific to their business situations.     

Use of an enzyme immunoassay to detect serum IgG antibodies to Haemophilus ducreyi

An experimental enzyme immunoassay (EIA) for detecting serum IgG antibody to Haemophilus ducreyi was developed using an ultrasonicated whole-cell antigen. The mean optical densities (OD) for sera from men with proven chancroid from Nairobi (47 patients) and Bangkok (72 patients) were significantly higher than those obtained from Nairobi men with genital ulcers not due to H. ducreyi, from Nairobi men with urethritis, from pregnant women in Nairobi, and from European men with sexually transmitted disease. When an OD of 0.500 was taken as the cutoff value, 89% and 55% of men with proven chancroid in Nairobi and Bangkok, respectively, were positive for H. ducreyi antibody, as compared with 2%-17% in the control groups. A rise in OD was observed in five of 18 patients with clinical chancroid. These results confirm the development of circulating antibodies in chancroid and suggest that this EIA may be useful for the diagnosis and epidemiological study of H. ducreyi infection.     

The pharmacokinetics of lignocaine in humans during a computer-controlled infusion.

Several types of chronic pain syndromes are effectively treated with sodium channel blockers such as lignocaine. Further investigation of this therapeutic modality would be facilitated by refinement of the parameters describing lignocaine distribution and elimination. This would allow precise lignocaine infusion by a computer-controlled infusion to attain and maintain stable target lignocaine concentrations. Arterial blood samples were obtained at frequent intervals during a computer-controlled infusion of lignocaine in 12 adult human volunteers. Plasma lignocaine concentrations of 1, 2, 3, 4 and 5 microg/ml were targeted for 15 min at each concentration. A three-compartment mammillary pharmacokinetic model best described the resulting concentration vs time profile. A population pharmacokinetic analysis was performed using three different techniques; the two-stage, pooled and mixed effects modelling. There was marked overshoot of the plasma concentration above the target prior to refinement of the pharmacokinetic parameters. The best parameters of a three-compartment mammillary model fit to the measured concentration using the pooled data approach were: V(1) = 7.44, V(2) =11.5 and V(3) = 97.71; Cl(1) = 0.585, Cl(2) = 2.23 and Cl(3) =1.64 l/min. Similarly calculated parameters using NONMEM were V(1) = 6.99, V(2) =12.2 and V(3) =1341; Cl(1) = 0.703, Cl(2) =1.24 and Cl(3) =1.49 l/min. The addition of age as a covariate of the pharmacokinetic parameters improved the model in both cases. Height, lean body mass and body surface area as covariates of the pharmacokinetic parameters did not improve the predicted value of the model. Prospective testing of the pharmacokinetic parameters will be required to define whether they function well. The refinement of pharmacokinetic parameters for the computer-controlled intravenous infusion of lignocaine will facilitate further research in pain therapy. Published lignocaine pharmacokinetic values have a relatively large central volume of distribution, and hence, when implemented as a computer-controlled infusion, result in dramatic overshoot shortly after targeting a higher plasma concentration. In light of the long-lasting pain relief provided by sodium channel blockade in neuropathic pain states, overshoot of plasma concentrations must be avoided if the concentration vs effect relationship is to be defined.     

Enrichment of glutamate in zinc-containing terminals of the cat visual cortex.

The presence of glutamate and GABA was examined in zinc-containing terminals of the cat visual cortex using a post-embedding immunogold method. The surface density of immunogold-labelling was also evaluated in morphologically defined ultrastructural elements, namely terminals having round synaptic vesicles and making asymmetrical synapses (RA boutons), terminals with flat vesicles and symmetrical synapses (FS) and glial cell processes. Glutamate immunoreactivity was highest in RA terminals and in zinc-containing boutons. It was lower in FS terminals and lowest in glial cell processes. GABA immunoreactivity was highest in FS terminals and low in all other ultrastructural elements analysed, including zinc-containing terminals. Therefore, zinc-containing terminals show an enrichment of glutamate and they are likely to use this amino acid as their neurotransmitter. Moreover, the fact that many RA terminals that are negative for zinc show an enrichment of immunoreactive glutamate suggests that zinc-containing fibres represent a subpopulation of the glutamate axonal network.     

The Rochester Diabetic Neuropathy Study: design, criteria for types of neuropathy, selection bias, and reproducibility of neuropathic tests

A cross-sectional survey and subsequent longitudinal study among diabetic residents of Rochester, MN--The Rochester Diabetic Neuropathy Study (RDNS)--is population-based and uses quantitative, validated, and unique end points to detect, classify, and stage neuropathy. Nondiabetic persons, drawn from the same population, serve as controls. For patients 10 to 70 years old, the RDNS cohort is representative of diabetics living in Rochester, MN. We assessed reproducibility of tests used to characterize and quantitate severity of neuropathy in 20 diabetic subjects without neuropathy and with varying severities of neuropathy. Using intraclass correlation coefficient (rI) as a measure of test reproducibility, we found high rI (usually 0.9 or better) with small confidence intervals for the Neurologic Disability Score (NDS); weakness subset of NDS (W-NDS); vibratory and cooling detection thresholds (using computer-assisted sensory examination [CASE] IV); compound muscle action potentials; sensory nerve action potentials; and motor nerve conduction velocities. There was good agreement among three trained observers for NDS and the W-NDS.     

F-19 MR imaging of glucose metabolism in the rabbit

Noninvasive metabolic magnetic resonance (MR) imaging reflecting glucose metabolism in the aldose-reductase-sorbitol (ARS) pathway was performed in the rabbit head; after administration of the fluorinated glucose analogue 3-fluoro-3-deoxy-D-glucose (3FD-glucose), fluorine-19 images were generated. Images of 3FD-glucose showed significant 3FD-glucose uptake by adipose tissue, indicating its buffering effects in case of excess loads of glucose. Images of 3-fluoro-3-deoxy-D-sorbitol (3FD-sorbitol) demonstrated the spatial distribution of aldose reductase activities and significant sorbitol accumulation in the lens. Images of 3-fluoro-3-deoxy-D-fructose (3FD-fructose) showed preferential uptake of fructose by muscle tissue. The extremely low toxicity of 3FD-glucose indicates promise for its clinical application in metabolic imaging.