Conditions for view invariance in the neural response to visual symmetry

Symmetry detection is slow when patterns are distorted by perspective, perhaps due to a time‐consuming normalization process, or because discrimination relies on remaining weaker regularities in the retinal image. Participants viewed symmetrical or random dot patterns, either in a frontoparallel or slanted plane (±50°). One group performed a color discrimination task, while another performed a regularity discrimination task. We measured a symmetry‐related event‐related potential (ERP), beginning around 300 ms. During color discrimination, the ERP was reduced for slanted patterns, indexing only the remaining retinal structure. During regularity discrimination, the same ERP was view invariant, and identical for frontoparallel or slanted presentation. We conclude that normalization occurs rapidly during active symmetry discrimination, while symmetry‐sensitive networks respond only to regularity in the retinal image when people are attending to other features.     

The use of octadecyl-bonded microparticulate silica in the separation of free and bound fractions during saturation analysis of vitamin D metabolites.

The use of octadecyl-bonded microparticulate silica to separate free and bound fractions during the saturation analysis of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D has been investigated. A slurry of octadecyl-bonded silica in an appropriate incubation buffer was prepared and used in parallel with a conventional dextran-coated charcoal suspension in several assay procedures. Standard curves, non-specific binding and plasma values were compared. A competitive protein binding assay for 25-hydroxyvitamin D and two radioreceptor assays and one radioimmunoassay for 1,25-dihydroxyvitamin D were investigated. In most cases the octadecyl-bonded silica preparation gave the more favourable results; its action was rapid, time- and temperature-independent, and it produced low non-specific binding and higher B0 values in all the assays examined. It was in our hands easier to use than dextran-coated charcoal. The use of octadecyl-bonded silica is recommended as an efficient agent for the separation of free and bound fractions in the saturation analysis of vitamin D metabolites.     

C7 radiculopathy: importance of scapular winging in clinical diagnosis.

Lesions of the seventh cervical (C7) root are common and cause a readily recognised neurological syndrome. Recognition of this pattern is essential in differentiating C7 root lesions from lesions of the brachial plexus or peripheral nerves. Serratus anterior weakness is not generally included in this syndrome. We report six verified cases of C7 radiculopathy in which weakness of the serratus anterior was present in addition to the usual findings. This was manifest as winging of the scapula, when pushing forward against a wall, either with the hands at shoulder level or, in some cases, only when the hands were lowered to waist level. This latter method of testing places the muscle at a mechanical disadvantage and reveals partial paralysis. Analysis of this clinical finding complements anatomical evidence suggesting that the powerful lower digitations of the muscle may be primarily supplied by the C7 root in some cases. Scapular winging, apparent either in the usual position or the modified position described here, should be recognised as consistent with a diagnosis of C7 radiculopathy. When present, this sign serves to differentiate C7 radiculopathy from lesions of the brachial plexus or radial nerve.     

THE CURRENT MANAGEMENT OF PARACETAMOL OVERDOSAGE

SUMMARY Paracetamol overdosage is a common problem, but severe poisoning occurs in only a small percentage of cases. A patient who has suffered paracetamol overdosage should be monitored carefully to ensure that a specialist liver unit can be contacted at the earliest signs of severe poisoning for optimal management and transfer. Paracetamol overdosage remains the most common cause of fulminant hepatic failure in the UK, with a mortality rate of 90%, but survival rates can be improved dramatically by specialist intensive care management, and with the advent of transplantation a previously untreatable group of patients can be treated successfully. However, a patient who is inadequately monitored and treated in the early stages after an overdose may deteriorate to an extent that renders them unsalvable by the time they arrive at the specialist centre.     

A simple technique for thromboembolectomy of the upper limb

Brachial emboli account for only 18% of arterial emboli and present as an uncommon emergency to surgeons. We have examined the route taken and probable outcome of arterial embolectomy of the upper limb in 31 cadaveric limbs using standard and Coude tipped embolectomy catheters. Using a standard embolectomy catheter, the larger of the two upper limb arteries was cannulated in only 42% of our series. However, using a 30 degree Coude tipped catheter, both radial and ulnar arteries could be cannulated in 87% of limbs, ensuring a more complete embolectomy without the need formally to expose the brachial artery bifurcation.     

Monoclonal antibodies raised to colorectal carcinoma antigens

The search for tumour markers was intensified with the advent of monoclonal antibody technology. To date no tumour specific markers have been found. Despite this, monoclonal antibodies have helped to identify cells in terms of their origin and function and therefore added a different dimension to studies of both benign and malignant disease processes. Advances in molecular biology have made cooperation between scientists and clinicians in all branches of medicine essential in order to piece together a more complete picture of any disease. This article describes the production and characterisation of two epithelial specific monoclonal antibodies (CAM5.2 and CAM17.1) with potential clinical value by a surgeon temporarily transposed to a laboratory environment.     

Disruption of a stapled anastomosis following therapeutic ultrasonics—Is there a risk?

PURPOSE: We examined the theoretic possibility that therapeutic ultrasound can disrupt a stapled gastrointestinal anastomosis. METHOD: A case is reported in which leakage of a stapled ileocolic anastomosis occurred following therapeutic ultrasound. Calculations are performed on the power of the ultrasound beam and its adsorption and dispersion in the tissue between the probe and anastomosis to establish its intensity at the anastomosis. RESULTS: Ultrasound intensity at the anastomosis in this patient was calculated at 10 to 46 mW/cm ².CONCLUSION: Although the calculated ultrasound intensities at the anastomosis do not appear to be very high, other factors such as “pressure doubling” and “stress concentration” at the stapled surface suggest that therapeutic ultrasound may cause staple disruption.