Going, going, gone . . . ? Implicit and explicit tests of conceptual knowledge in a longitudinal study of semantic dementia

Patients suffering from semantic dementia provide important constraints on theories of the structure and organisation of semantic memory. In this article we report one such patient, AM, whose progressive deterioration of semantics enables us to address the much-debated issue of whether conceptual structure is hierarchically organised. The hierarchical account predicts that brain damage should impair lower levels of the hierarchy (property information) before affecting higher level (category) information (Warrington and Shallice, Q. J. Exp. Psychol. 1975, 27, 635–657). We evaluate this prediction by repeated testing of AM in two studies—a semantic priming task and a verification task—over an 18 month period, contrasting the progressive deterioration of properties (functional and perceptual) and category relations (category co-ordinates and category labels). Properties were preserved longer than category information, arguing against a hierarchical account of semantic memory. In addition, functional properties were most robust to brain damage, supporting our claim that functional information plays a special role in semantic representations (Durrant-Peatfield et al., Proc. 19th Ann. Conf. of the Cognitive Science Society. Erlbaum, Mahwah, NJ, 1997, pp. 193–198. Tyler et al., Cognitive Neuropsychol. 1997, 14, 511–545).     

Estimating IQ from Adaptive Behaviour Information in People with Moderate or Severe Intellectual Disability

It is often useful in studies of intellectual disability to be able to stratify the sample in terms of intellectual level. However, this information is sometimes difficult to obtain, and can involve a great deal of time if full IQ assessments are performed. This study explores the accuracy with which IQ scores can be projected by multiple regression from adaptive behaviour scores provided by informants. Fifty-one people with moderate, severe or profound intellectual disability received IQ assessments using the Kaufman Assessment Battery, and adaptive behaviour assessments using the Adaptive Behavior Scales (ABS). Ninety percent of projected estimates differed by less than 30% from that estimated by the K-ABC. Mean percentage divergence between actual and predicted estimates of IQ for the 51 cases for which all data were available was 15.0%. Limitations of the technique are discussed. The actual coefficients for calculating IQ are given in tabular form.     

Starch, gloves and extradural catheters

We have investigated contamination of extradural catheters during normal handling with starch powdered gloves. In the laboratory, extradural catheters were handled in sterile fields with both powdered and non-powdered gloves, simulating preparation for patient insertion. The catheters together with glove samples were then examined using a Zeiss 940 scanning electron microscope. Microscopy of samples revealed starch contamination of the catheters handled with powdered gloves, especially in the side hole areas. We conclude that extradural catheters may be contaminated easily by starch powder from surgical gloves. This powder may then be deposited into the extradural space. The effect of starch in the extradural space is not known but starch is known to cause inflammatory and granulomatous reactions in other parts of the body as well as being directly allergenic. Powder contamination of catheters may be avoided easily by the use of powder-free gloves and we feel that these should be used whenever possible.      

Outcomes of cardiopulmonary resuscitation in dialysis patients.

Patients with renal failure are believed to have a poor survival rate after cardiopulmonary resuscitation, but there is little specific information about the outcomes of cardiopulmonary resuscitation in dialysis patients. To be better able to inform dialysis patients and assist them in decision making about cardiopulmonary resuscitation, the eight-year experience with cardiopulmonary resuscitation in dialysis patients at a university dialysis program was analyzed and outcomes were compared with those of a control group of nondialysis patients undergoing cardiopulmonary resuscitation during the same time period in the same hospital. Of 221 dialysis patients experiencing cardiopulmonary arrest, 74 (34%) had CPR compared with 247 (21%) of 1,201 control patients (P = 0.0002). Six of 74 (8%; 95% confidence interval, 2 to 14%) dialysis patients survived to hospital discharge compared with 30 of 247 (12%; 95% confidence interval, 8 to 16%) control patients (P = not significant). At 6 months after CPR, 2 (3%) of 74 dialysis patients were still alive compared with 23 (9%) of 247 controls (P = 0.044); this difference was not explained by age or comorbid conditions. Twenty-one (78%) of the 27 successfully resuscitated dialysis patients died a mean of 4.4 days later; 95% were on mechanical ventilation in an intensive care unit at the time of death. It was concluded that cardiopulmonary resuscitation is a procedure that rarely results in extended survival for dialysis patients. In discussions about cardiopulmonary resuscitation with dialysis patients, nephrologists should provide this information.     

Artificial blood: current status of hemoglobin solutions.

Attempts to develop a hemoglobin-based red cell substitute have spanned many decades, but no clinically useful product has been produced to date. The issues preventing clinical application primarily are ones of safety--not efficacy. Numerous animal studies have documented the efficacy of SFH. Although effective, the solution has limitations that have caused concern. Oncotic considerations limit the concentration of the infusate SFH to 6 to 8 g/dL, or half-normal. Owing to the loss of organic phosphate modulators of P50, such as 2,3-DPG, the P50 of SFH is typically between 12 and 14 mm Hg, which is also half the normal value. And finally, the intravascular half-life of SFH is too short, ranging only from 2 to 6 hr. Polymerization provides a means of correcting these limitations. The high oxygen affinity can be greatly diminished by covalent binding of pyridoxal-5'-phosphate to the N-terminal of the chains. Colloid osmotic pressure exerted by a protein solution is proportional to the number of discrete colloid particles. Through polymerization, the number of colloid particles is reduced, leading to a decrease in COP. Data show that this can be achieved in a reproducible fashion. The rate at which COP diminishes determines the yield of polymeric species, as well as their molecular weight distribution. Polymerization can be controlled to result in a yield of 75% to 85% polymers with a molecular weight distribution of 128 to 400 kd. The number average and the weight average molecular weights indicate that the large proportion of polymers represent the cross linking of two tetramers. The data that reflect the interaction of oxygen with poly-SFH-P indicate that the oxygen carrying function of hemoglobin has not been significantly altered by the chemical modifications. The binding coefficient of oxygen is unchanged. As anticipated, there is a loss of cooperativity (diminished Hill coefficient) between the hemoglobin chains, suggesting structural restrictions in the polymeric species because of cross linking. A reduced alkaline Bohr effect is the expected result, and data confirm this. Finally, some increase in oxygen affinity is to be expected with polymerization. This is indeed the case, although the P50 of poly-SFH-P is comparable to banked blood (18 to 22 mm Hg). To be clinically useful, a modified hemoglobin solution requires a reasonable shelf-life.(ABSTRACT TRUNCATED AT 400 WORDS)