Testis-specific and sex-associated hexokinases in Drosophila melanogaster.

Hexokinases of Drosophila melanogaster were investigated by starchgel electrophoresis. A hexokinase is present in both sexes during earlier stages of development, but it persists only in male adults. In addition, in this species there is a testis-specific hexokinase which is first observed during the pupal period.

Developmental variation in the isoenzymes of human liver and gastric alchhol dehydrogenase.

The isoenzyme patterns of alcohol dehydrogenase from human liver and stomach are different in the fetal, newborn, childhood, and adult periods of life. This provides additional evidence that the fetal and adult alcohol dehydrogenases are qualitatively different. Gastric and hepatic isoenzyme patterns also differed from each other.

Deriving behavioural receptive fields for visually completed contours.

The visual system is constantly faced with the problem of identifying partially occluded objects from incomplete images cast on the retinae. Phenomenologically, the visual system seems to fill in missing information by interpolating illusory and occluded contours at points of occlusion, so that we perceive complete objects. Previous behavioural [1] [2] [3] [4] [5] [6] [7] and physiological [8] [9] [10] [11] [12] studies suggest that the visual system treats illusory and occluded contours like luminance-defined contours in many respects. None of these studies has, however, directly shown that illusory and occluded contours are actually used to perform perceptual tasks. Here, we use a response-classification technique [13] [14] [15] [16] [17] [18] [19] [20] to answer this question directly. This technique provides pictorial representations - 'classification images' - that show which parts of a stimulus observers use to make perceptual decisions, effectively deriving behavioural receptive fields. Here we show that illusory and occluded contours appear in observers' classification images, providing the first direct evidence that observers use perceptually interpolated contours to recognize objects. These results offer a compelling demonstration of how visual processing acts on completed representations, and illustrate a powerful new technique for constraining models of visual completion.

Time course of amodal completion revealed by a shape discrimination task.

We measured the extent of amodal completion as a function of stimulus duration over the range of 15-210 msec, for both moving and stationary stimuli. Completion was assessed using a performance-based measure; a shape discrimination task that is easy if the stimulus is amodally completed and difficult if it is not. Specifically, participants judged whether an upright rectangle was longer horizontally or vertically, when the rectangle was unoccluded, occluded at its corners by four negative-contrast squares, or occluded at its corners by four zero-contrast squares. In the zero-contrast condition, amodal completion did not occur because there were no occlusion cues; in the unoccluded condition, the entire figure was present. Thus, comparing performance in the negative-contrast condition to these two extremes provided a quantitative measure of amodal completion. This measure revealed a rapid but measurable time course for amodal completion. Moving and stationary stimuli took the same amount of time to be completed (approximately 75 msec), but moving stimuli had slightly stronger completion at long durations.

Impact of spinal cord injury on self-perceived pre- and postmorbid cognitive, emotional and physical functioning.

STUDY DESIGN: Cross-sectional study with repeated measurements. OBJECTIVES: To examine the patient's perspective of the impact of spinal cord injury (SCI) on physical, cognitive, emotional function, and quality of life (QOL). SETTING: Australia. METHODS: A sample of 63 patients with SCI, 32 of whom had recent injuries, and 31 with established injuries were administered the Ruff Neurobehavioral Inventory to examine patients' subjective evaluation of pre- and post-injury functioning. Current happiness levels were also evaluated using the Subjective Happiness Scale. A follow up assessment was performed 6 months later to examine changes over time. RESULTS: A significant difference was found between perception of pre- and postmorbid function on composite Cognitive (t=5.99, df=62, P<0.001), Physical (t=11.56, df=62, P<0.001), and QOL (t=7.16, df=62, P<0.001) scales and on several of the Emotional subscales including anxiety, paranoia and suspicion, and substance abuse (P<0.001). A series of hierarchical regression analyses indicate that post-SCI pain was a significant predictor of: cognitive (R(2)=0.20, P<0.001); emotional (R(2)=0.13, P<0.004); and of QOL (R(2)=0.22, P<0.001) functioning. With the exception of a decrease in happiness (P<0.01), there were no significant changes in any measures over the 6 month time period. CONCLUSIONS: There are significant changes in patients' perceptions of physical and cognitive functioning, and of QOL before and after SCI and some aspects of emotional functioning. Pain has a significant adverse effect on functioning. Happiness decreased slightly in the 6 months between surveys.

Approaches to the evaluation of the genetic counselor.

Regular, formal structured evaluation of the counseling skills of the genetic counselor should be a part of every counseling program. There is no ideal method of evaluation. Each has advantages and disadvantages. A combination of methods, determined by funds and equipment available probably presents the best approach to this problem. Formal studies of the optimum methods of counselor evaluation and the best criteria to be used are needed to provide definitive answers to the problem of how best to evaluate the performance of genetic counselors.

Tests of so-called genetic susceptibility.

During the past two decades a number of inherited polymorphic proteins and enzymes have been identified in different ethnic groups. Certain biochemical markers appear to be associated with susceptibility to harmful effects of the environment. This paper reviews the potential for using these markers to determine whether affected persons ought to be excluded from certain jobs or from the environment(s) of specific settings in the workplace. This paper will also attempt to identify the criteria that should be used before it is scientifically and ethically justified to use these markers to "protect" workers and/or persons from harm by not allowing them to work in a specific setting or with specific agents to which they have been deemed to be at special risk for injury.

Psychosocial aspects of genetic counseling.

A competent and effective genetic counselor must recognize and deal with the psychological defense mechanisms which affected persons and parents of affected children use to cope with the strain of genetic disease in the family. Denial, guilt, hostility, grief and mourning and the psychology of defectiveness are all potent emotional factors that must be dispelled or worked through before parents should make reproductive decisions. If the counseling experience is to be satisfactory, the counselor must help parents meet the immediate and long term social needs of affected individuals in addition to their medical needs.

PIP: Genetic counseling involves a complex interaction of social, medical, and psychological factors. It is not enough for a genetic counselor to present information about the genetic aspects and risks of the situation. The counselor must help the parents deal with the psychosocial aspects of their situation. Such defense mechanisms as denial, guilt, hostility, grief, and mourning are discussed. The counselor must help the parents deal with these feelings before an informed decision can be made regarding future reproductive behavior.

Linkage studies in Lenz microphthalmia.

Glucose-6-phosphate dehydrogenase (G6PD) phenotype studies were done on a black family with X-linked heredofamilial bilateral microphthalmia (HBM). Three crossovers and three non-crossovers were detected in three informative matings of four generations yielding a recombination value of 0.5. These findings do not provide evidence for linkage between the G6PD and HBM loci, suggesting either that the G6PD and HBM loci are far apart on the X chromosome or that HBM in this family is inherited as an autosomal dominant male sex-limited trait.

Special considerations for minority participation in prenatal diagnosis.

Parents who use information from prenatal diagnosis in family planning may be faced with difficult decisions. For a variety of reasons, the communications and decision-making process may be substantially more complex and difficult if the parents are members of a minority group. Unless a number of special considerations are kept in mind when programs of prenatal diagnosis for minorities are developed, such programs may be more harmful than beneficial.