Episodic and semantic contributions to older adults' autobiographical recall.

The authors examined episodic and semantic contributions to 2 salient features of older adults' autobiographical recall: the reminiscence bump and the retention effect. Forty well-educated and healthy older men (mean age = 72.5 years; SD = 1.

The role of dispositional and situational factors in cognitive interference.

Two studies investigated the cross-temporal stability and cross-situational consistency of cognitive interference. In Study 1, 70 college students reported on the intrusive thoughts they experienced during 2 course examinations and a self-reflective task. In Study 2, 55 college athletes reported on intrusive thoughts following 2 course examinations and 2 regular season football games.

Finding final postures.

In this study, a model of movement planning (Rosenbaum, Engelbrecht, Bushe, & Loukopoulos, 1993a, 1993b; Rosenbaum, Loukopoulos, Meulenbroek, Vaughan, & Engelbrecln, 1995), in which movements are generated on the basis of the efficacy of different possible goal postures, was tested. The model predicts which limb segments will be used and how the segments will be combined in reaching. The model's predictions were compared with observations from a study in which seated participants reached for targets in a sagittal plane, using the hip, shoulder, and elbow.

Apoptosis in cavitation of middle ear space.

Mesenchyme cells surround early ossicles in the developing middle ear, then are replaced by space that is created by what has been described as an expansion of the pharyngeal pouch. Cell death has not been considered important in cavitation of chick middle ear (Jaskoll and Maderson [1978] Anat. Rec.

The Saccharomyces cerevisiae YCC5 (YCL025c) gene encodes an amino acid permease, Agp1, which transports asparagine and glutamine.

The yeast YCC5 gene encodes a putative amino acid permease and is homologous to GNP1 (encoding a high-affinity glutamine permease). Using strains with disruptions in the genes for multiple permeases, we demonstrated that Ycc5 (which we have renamed Agp1) is involved in the transport of asparagine and glutamine, performed a kinetic analysis of this activity, and showed that AGP1 expression is subject to nitrogen repression.

Right-left asymmetry of cell proliferation predominates in mouse embryos undergoing clockwise axial rotation.

Background: Differential growth is fundamental to most mechanisms proposed for axial rotation in amniotes. Other mechanisms such as changes in cell shape are not consistently suggested by ultrastructure. Lateral asymmetries in cell proliferation exist in mouse and chick embryos undergoing normal, anticlockwise axial rotation, but there has been no investigation of inverse clockwise rotation that could test the correlation.

The control of morphogenesis in Saccharomyces cerevisiae by Elm1 kinase is responsive to RAS/cAMP pathway activity and tryptophan availability.

Many fungi undergo a morphological transition to filamentous growth in response to limiting nutrient conditions. Constitutively elongated Saccharomyces cerevisiae mutants (elm) have been isolated; the ELM1 gene encodes a putative serine/threonine protein kinase. A novel allele, elm1-15, has been isolated in an S288C-derived strain, which causes a pleiotropic phenotype, including media-specific growth effects, abnormal morphology and altered stress response, in cells that are auxotrophic for tryptophan.

Psychometric and psychodynamic correlates of first memories in younger and older adults.

We conducted two studies that identified some of the psychometric and psychodynamic correlates of the first memories of younger and older adults. Collectively, these studies revealed that: (a) performance on the Weschler Adult Intelligence Scale-Revised (WAIS-R) vocabulary and digit-span backwards tasks was negatively related to the age of younger and older adults' first memories, (b) performance on the death preparation subscale of the Reminiscence Function Scale was inversely related to age of older adults' first memories, but positively related to the age of younger adults' first memories, and (c) the use of internalizing defenses as measured by the Defense Mechanism Inventory was predictive of the age of younger, but not older, adults' first memories. The implications of these data for theories of infantile amnesia and life review are discussed.

Crystal structure and resonance Raman studies of protocatechuate 3,4-dioxygenase complexed with 3,4-dihydroxyphenylacetate.

The crystal structure of the anaerobic complex of Pseudomonas putida protocatechuate 3,4-dioxygenase (3,4-PCD) bound with the alternative substrate, 3,4-dihydroxyphenylacetate (HPCA), is reported at 2.4 A resolution and refined to an R factor of 0.17.

The branched-chain amino acid permease gene of Saccharomyces cerevisiae, BAP2, encodes the high-affinity leucine permease (S1).

The amino acid leucine has been shown previously to be transported into a yeast cell by at least three permeases: the general amino acid permease, a high-affinity permease (S1) and a low-affinity permease (S2). We isolated the gene BAP2 as a multicopy suppressor of the YPD- phenotype of aat1leu2 yeast. BAP2 has been identified previously as encoding an amino acid permease which transports branched-chain amino acids.

The effects of skin temperature on the detection and discrimination of tactile stimulation.

Detection thresholds and intensity-difference thresholds were measured on four subjects ranging in age from 19 to 22 years. The stimuli were 250-Hz bursts of vibration applied through a 3.0 cm2 contactor to the thenar eminence of the right hand.

Olfactory conditioning impairment following posttraining NMDA receptor blockade in neonatal rats.

Six-day-old Sprague-Dawley rat pups were exposed to peppermint odor paired with tactile stimulation (stroking the skin with a paint brush) for twenty 10-s conditioning trials, and their olfactory preference was tested the next day. In Experiment 1, pups that had received an injection of the noncompetitive N-methyl-D-aspartate receptor antagonist MK-801 (0.1 mg/kg, i.

Effects of stimulus duration on the amplitude difference limen for vibrotaction.

Vibrotactile amplitude difference limens (DLs) were measured by the continuous pedestal and gated pedestal methods. In both cases, the relative DL decreased as a function of the intensity of the stimulus and the results, in most cases, could be described as a near miss to Weber's law. DLs measured by the continuous pedestal method were found to decrease substantially as a function of increases in stimulus duration over a range of 12 to 1000 ms.

Apoptosis removes chick embryo tail gut and remnant of the primitive streak.

Removal of transient features in morphogenesis of chick embryo tail is by programmed cell death. We used ApopTagTM (Oncor, Gaithersburg, MD) with the peroxidase/diaminobenzidine (DAB) procedure to correlate apoptosis with earlier reports of patterns of cell death in stage HH17-25 embryos, and our results suggest that the cell death inferred with supravital staining and appearance of cells in morphogenesis of the tail bud is programmed cell death called apoptosis. Apoptosis markers in tail bud are most abundant in the median cell cord of occluded degenerating tail gut.

Cognitive effects of life stress and learned helplessness.

Abstract Stressful life events and learned helplessness attributional styles have been shown to impact a variety of personal outcomes. This study examined how these factors influence two classes of cognitive behaviors: the occurrence of intrusive thoughts and performance in memory and verbal-spatial reasoning tasks. Negative life change and attributions for negative events predicted different types of cognitive responses.

The effects of aging on information-processing channels in the sense of touch: III. Differential sensitivity to changes in stimulus intensity.

Detection thresholds and difference limens were measured for 16 subjects ranging from 19 to 91 years of age. The stimuli were 250-Hz bursts of vibration applied through a 3.0-cm2 contactor to the thenar eminence of the right hand.

Cooperative selection of movements: the optimal selection model.

How one selects a movement when faced with alternative ways of doing a task is a central problem in human motor control. Moving the fingertip a short distance can be achieved with any of an infinite number of combinations of knuckle, wrist, elbow, shoulder, and hip movements. The question therefore arises: how is a unique combination chosen? In our model, choice is achieved by consideration of the similarity between the task requirements and the optimal biomechanical performance of each limb segment.

Some temporal parameters in vibrotactile forward masking.

Tactile thresholds for detecting a 250-Hz signal of variable duration presented at variable times after the termination of a 250-Hz 700-ms masking stimulus were measured. It was found that the threshold shift resulting from the presentation of the masking stimulus declined as functions of the duration of the signal and the duration of the time interval between the masking stimulus and signal. Both of these effects were found to be attributable to an increase in the time interval between the offset of the masking stimulus and the offset of the signal.

Vibrotactile forward masking: effects of the amplitude and duration of the masking stimulus.

Tactile thresholds for detecting a 50-ms signal presented 25 ms after the termination of a masking stimulus increased as a function of the amplitude level and duration of the masking stimulus. The effects were similar in both the P and NP I channels measured at 250 and 20 Hz, respectively. It was concluded that the increased masking caused by increasing the duration of the masking stimulus resulted from processes other than or in addition to temporal integration--the latter being a characteristic of the P, but not the NP I, channel.

The effects of masking on the growth of vibrotactile sensation magnitude and on the amplitude difference limen: a test of the equal sensation magnitude-equal difference limen hypothesis.

In this study, the hypothesis that the difference limen (DL) for the detection of differences in amplitude of vibrotactile stimuli is independent of the slope of the sensation magnitude function was tested. The slope of the sensation magnitude function was varied by presenting test stimuli in the presence of or in the absence of vibrotactile noise. The slopes of the sensation magnitude functions were determined through a matching technique in which the subject adjusted stimulus amplitudes of a 250-Hz stimulus presented alone and a 250-Hz stimulus presented simultaneously with a masking noise, so that their sensation magnitudes were equated.

Lymphocytes and promonocytes attach to the synthetic [Tyr5,12, Lys7]- polyphemusin II peptide.

The [Tyr5,12,Lys7]-polyphemusin II peptide (T22) has been shown to inhibit HIV-1 replication in lymphocytes. The mechanism of T22 inhibition of HIV-1 replication is not known but may involve T22 competition with HIV-1 for attachment sites on the plasma membrane of targeted cells. Here we find that three human immunocyte cell lines (H9, Jurkat, and U-937) attach to T22.

Domains of differential cell proliferation and formation of amnion folds in chick embryo ectoderm.

Patterns of cell proliferation in ectoderm epithelium that will form avian amnion correlate with morphogenesis, but not in an obvious pattern with respect to large-scale folding. At sites where the pre-axial amnion folds will first appear in 4- to 8-somite embryos, patterns of proliferation do not separate into domains that presage location of the single pre-axial fold that is commonly described in embryology texts. Instead, increased cell proliferation occurs in a significant, bilateral pattern.

The effects of masking on vibrotactile temporal summation in the detection of sinusoidal and noise signals.

Thresholds for the detection of vibrotactile signals of varied duration applied to the thenar eminence were measured in the absence of and in the presence of a masking stimulus. Signals were 250- and 500-Hz sinusoids and noise bursts with bandwidth limited to 250-1000 Hz. The masking stimulus was either a 250-Hz sinusoid, which was presented in phase with the signal when it was sinusoidal, or noise.