Search

Objective: Few studies focus on upper limbs in bilateral cerebral palsy (CP) despite potential bimanual deficits. Electroencephalography (EEG) was utilized to investigate brain mechanisms underlying upper limb tasks in bilateral CP and typical development (TD) and relationships to function., Methods: 26 (14 CP; 12 TD) completed the Box and Blocks Test and transport task with paper, sponge or mixed blocks, while recording EEG and motion data., Results: Group effects for path time, path length and Box and Blocks Test revealed bimanual deficits. Four sensorimotor-related EEG clusters were identified. Group effects were found in premotor and dominant motor clusters with greater beta event-related desynchronization (ERD) in CP. Hand and hand by group effects were found in the dominant motor cluster, showing greater ERD with the more affected hand in CP. Condition effects were prominent in the posterior parietal cluster with higher ERD reflecting greater difficulty in force modulation., Conclusions: Higher brain activation associated with greater bimanual deficits is similar to our lower limb findings but contrasts studies in TD or unilateral CP linking higher ERD to greater proficiency., Significance: Bilateral CP shows overreliance on the dominant hemisphere with the less functional hand and higher brain activity presumably related to excessive intracortical connectivity., Competing Interests: Disclosure None of the authors has any disclosures or conflicts related to this manuscript., (Published by Elsevier B.V.)

An immunoassay for prostatic acid phosphatase is described in which a high degree of specificity for the prostatic isoenzyme, obtained by the use of monoclonal antibodies, is combined with great sensitivity, made possible by enzyme-amplified measurement of the combination of the isoenzyme with its antibody. The increase in sensitivity thus achieved is of the order of 170 times that of conventional methods of measurement. The advantages of the enzyme-amplified method have been shown to be particularly useful in detecting and monitoring small abnormalities of prostatic acid phosphatase levels in patients with prostatic cancer.

Enzyme-amplified immunoassays have been adapted for electrochemical measurement, using an NAD+/NADH redox cycle coupled to an electrode via the active site of diaphorase. Two amperometric methods are described, the first employs an organic conducting salt electrode, NMP+/TCNQ-; the second a platinum wire with ferricyanide as electron transfer mediator. In an immunoenzymometric assay for human prostatic acid phosphatase the sensitivities of the electrochemical methods were comparable to that achieved with the existing optical technique, but the dynamic range of the electrochemical assays was increased by at least two orders of magnitude. It is proposed that electrochemical enzyme-amplified immunoassays may eventually replace their optical counterparts.

A method for greatly enhancing the sensitivity of assays employing enzyme labels is described which offers advantages in assays for a wide range of analytes. The principle of the new approach is that the enzyme label gives rise to a catalytic activator for a specific secondary detection system, the activity of which is measured and related back to the amount of label present and thus of the analyte it is being used to determine (C.H. Self, Eur. Pat. Appl. 80303478.4, 15.4.81 exclusively licenced to IQ (Bio) Ltd.). The general principle of enzyme amplification is illustrated by using alkaline phosphatase as the labelling enzyme and nicotinamide adenine dinucleotide phosphate (NADP) as its substrate. The nicotinamide adenine dinucleotide (NAD) formed catalytically activates a strictly NAD specific redox cycle which produces a coloured formazan as the end product. The measured absorbance is at least two orders of magnitude greater than that achieved by conventional methods. The application of this method to immunoassay is demonstrated by a sensitive, rapid and precise assay for human prostatic acid phosphatase (PAP). Some of the many other applications of this methodology are discussed.

Enzyme immunoassays (EIA) are now used for the quantitation of a wide range of clinically important analytes and have, in many cases, replaced radioimmunoassays, though without improving on the sensitivity of the latter technique. We describe a general enzyme-amplification method which can be used to increase both the speed and the sensitivity of EIA. In this method, the enzyme label is used to catalyse the dephosphorylation of nicotinamide adenine dinucleotide phosphate (NADP+); the NAD+ so formed then catalytically activates an NAD+-specific redox cycle, yielding an intensely coloured formazan dye. The application of this new enzyme detection method has made possible an assay for human thyroid-stimulating hormone (TSH) with a sensitivity of 1 X 10(-5) IU/1 and a progesterone assay which takes only 15 min to complete.

A method is described for increasing the response of enzyme immunoassays employing alkaline phosphatase as the label initiating 2 sequential catalytic reactions. First, NADP is dephosphorylated to produce NAD, which catalytically activates a specific redox-cycle involving the enzymes alcohol dehydrogenase and diaphorase. During each turn of the cycle 1 molecule of a tetrazolium salt is reduced to an intensely coloured formazan. The method is capable of detecting as little as 0.01 amol alkaline phosphatase, and when applied to an immunoassay for TSH a sensitivity (zero + 2.5 standard deviations) of 0.0013 mIU/l was obtained.