Eight years'' experience with a structured clinical examination

A structured clinical examination has been an integral component of the final-year examinations conducted by the Departments of Medicine and Surgery at the University of Adelaide for the last 8 years. It has been used as an alternative to the traditional clinical examination. This paper describes the results of ongoing student and examiner surveys carried out to determine their views and satisfaction with this new approach. It also briefly discusses the feasibility of introducing such an examination into a conventional medical school environment. The surveys showed a remarkable level of acceptance and support by both students and examiners. This positive reaction has been maintained over the 8-year period. The main reasons seem to be its perceived relevance and fairness. Students also appear to be directing their learning in a direction thought desirable by teachers. No significant problems have been encountered with the practical implementation of the method.     

The Effect of Quisqualic Acid-Induced Lesions of the Nucleus Basalis Magnocellularis on Latent Inhibition

Latent inhibition (LI) is a reduction in the rate of acquisition of a Pavlovian conditioned response that results from prior nonreinforced preexposure to a conditioned stimulus (CS). LI has been suggested to reflect the operation of mechanisms involved in stimulus selection for subsequent cognitive processing. The present experiment was conducted to assess the effect of bilateral lesions of the nucleus basalis magnocellularis (NBM) on LI employing a conditioned emotional response paradigm. Bilateral lesions of the NBM were produced by administration of 0.12 M quisqualic acid and resulted in decreased cortical acetylcholinesterase staining, as well as a 40% reduction in cortical choline acetyltransferase activity. Following lever press training, preexposed animals received 40 presentations of a 60-s tone CS. Nonpreexposed animals received no tone presentations. Acquisition of conditioned suppression was then assessed over the course of 4 tone-shock (0.6 mA, 0.5 s) pairings. Control, preexposed animals displayed a retarded rate of acquisition in comparison to nonpreexposed controls, thereby demonstrating that the parameters used in the present experiment produced LI. In contrast, lesioned animals preexposed to the CS acquired conditioned suppression as readily as non-preexposed lesioned animals. However, the acquisition of conditioned suppression in both lesioned groups was found to be similar to that displayed in the preexposed control group. This pattern of results was interpreted as being attributable to a lesion-induced impairment in the ability to maintain stimulus processing, rather than a deficit in the ability to filter a stimulus. Copyright © 1996 Elsevier Science Inc.     

Advances in processing of surface myoelectric signals: Part 1

During sustained voluntary or electrically elicted muscle contractions the surface myoelectric signal is nonstationary and it undergoes progressive changes reflecting the modifications of the motor unit action potentials and their propagation velocity. In particular, during sustained electrical stimulation, the evoked signals show progressive amplitude, time scaling and shape modification. The quantitative evaluation of these changes is important for non-invasive muscle characterisation and may be performed in either the time or frequency domain using parametric and nonparametric spectral analysis as well as alternative methodologies. The paper introduces the detection techniques, reviews and compares the methods of spectral estimation based on FFT and autoregressive models, and discusses their applications and limitations in extracting information from the surface myoelectric signal with particular regard to myoelectric manifestations of localised muscle fatigue during sustained contractions.     

羊水细胞培养宫内诊断的应用(附120例分析)

报告120例羊膜腔穿刺羊水细胞培养结果:在成功的99例中,发现二例染色体异常,核型为47,xy,+18和46,xx/47,xx,+F,在21例失败中出现一例眼球畸形。培养成功率为82.5%;染色体异常检出率为2.02%。无一例因羊膜腔穿刺而导致流产,但出现一例轻度羊水栓塞合并症。并对羊水细胞培养在产前宫内诊断中应用价值及术后并发症进行了讨论。     

Titration of duration discrimination in behavioral pharmacology and toxicology

This study investigated a discrete-trial, titration duration discrimination procedure in behavioral pharmacology. Pentobarbital and d-amphetamine, measured with this procedure, selectively affected discrimination more than response tendencies. Pentobarbital also tended to affect selectively discrimination of longer durations, whereas d-amphetamine did not. Further experiments showed that (1) other algorithms for modulating stimulus duration are useful in behavioral pharmacology and toxicology, (2) threshold estimates are similar with the method of constant stimuli and the method of titration, and (3) this titration procedure permits the separate examination of drug effects upon discrimination and upon response tendencies; the fixed-interval procedure does not. Baseline variability was an important correlate of drug effects in that the endpoints with more variable baselines were also more sensitive to drugs.     

Validation of a self-administered diet history questionnaire using multiple diet records

The validity of a self-administered diet history questionnaire has been estimated using as the reference data the mean of three 4-day diet records collected over the year prior to the administration of the questionnaire, in 1985–1986. Subjects were women ages 45–70 years, participants in the Women's Health Trial Feasibility Study, a multi-center clinical trial in which some women were randomized to be taught to adopt and maintain a low-fat diet, while others maintained their usual diet. The questionnaire produced group mean nutrient estimates closely approximating the values obtained by three 4-day records, e.g. in the usual-diet group, 37.7% of calories from fat by both food records and by questionnaire, and in the low-fat, group, 21.3% of calories from fat by food records and 23.7% of calories from fat by questionnaire. Correlations between questionnaire and diet records for per cent of calories from fat were 0.67 and 0.65 respectively in the two groups; most correlations were in the 0.5–0.6 range, and were similar to those achievable by a single 4-day food record.     

Students teaching students: a medical school peer tutorial programme

A peer tutorial programme which is available to all first- and second-year medical students has been in operation at Case Western Reserve University School of Medicine since 1972. A retrospective study of the classes of 1982, 1983 and 1984 was undertaken to assess the participation levels in the tutorial programme and to compare the participation level to available performance parameters. The analysis revealed that 54% of the first-year classes and 22% of the second-year classes participated in the peer tutorial programme. X2 analysis of the data demonstrated that the relationship between participation in the tutorial programme and performance on examinations reached statistical significance. The results suggested that an open peer tutorial programme responded to the needs, both cognitive and affective, of medical students.     

Pixel value modification using RVG-4 automatic exposure compensation for instant high-contrast images

The RVG-4 permits automatic exposure compensation (AEC). The purpose of this investigation was to determine the effects of AEC on image contrast. Images were made either with or without a dental QA jaw phantom using a fixed image projection geometry. Exposures were 6.3 through 27.3 μC/kg using an X-ray generator operated at 70 kVp. Region of interest pixel value distributions were measured at tissue thicknesses in this phantom, and the average pixel values and signal-to-noise ratios (SNR) were calculated. The use of AEC without an object in place resulted in a disproportionate relationship between pixel value and exposure with a marked reduction in SNR. The use of AEC on under- and over-exposed images of the phantom simultaneously enhanced image contrast and reduced SNR. Thus, AEC provides a convenient and quick method for achieving high-contrast images with sub-optimal exposures, however, this could lead to inappropriate patient dosages if the function is used for over-exposed images. AEC reduces the SNR and produces disproportionate pixel values relative to exposure.     

Calcium intake in the elderly: validation of a dietary questionnaire

Epidemiological studies of calcium and osteoporosis have been hampered by the lack of a suitable tool for assessing calcium intake. This report describes a new frequency and amount questionnaire for measuring present and past calcium intake in the elderly. The validity of the questionnaire was tested against two commonly used standards of dietary assessment, five-day duplicate diets and seven-day weighed dietary inventories. The resulting correlation coefficients were, respectively, r = 0.76 and r = 0.69, while that for repeatability was r = 0.84. Furthermore, the questionnaire categorized subjects into thirds of the distribution of intake with almost no gross misclassification. It is suggested that the present findings may be extended to the majority of normal, healthy elderly subjects, implying wide application for the questionnaire in the assessment of calcium intake in the elderly.