Marked differences in olfactory sensitivity and apparent speed of forebrain neuroblast migration in three inbred strains of mice

In the adult forebrain, new neuroblasts constantly migrate from the subventricular zone along the rostral migratory stream to the olfactory bulb, where many become neurons. It is unclear whether this process is different in commonly used mouse strains and whether it is related to olfactory function. Adult male BALB/c, C57BL/6, and 129/S1 (formerly 129SV) mice were tested for olfactory sensitivity plus discrimination, using male mouse urine from the two other strains. BALB/c mice had the greatest olfactory sensitivity, followed by 129/S1, and C57BL/6 mice, by an order of magnitude each. Newly formed cells were pulse-labeled for 3 h with i.p. 5-bromo-2'-deoxyuridine (BrdU) injections and the animals analyzed 24 h later. In 129/S1 mice, a greater proportion of neuroblasts were present closer to the olfactory bulb than in BALB/c mice, followed by C57BL/6 mice. The total number of BrdU-labeled cells did not differ, suggesting differences in migration and not proliferation. The impaired olfactory function in C57BL/6 mice might be caused by the reduced number of neuroblasts that reach the olfactory bulbs. However, olfactory function in BALB/c and 129/S1 mice did not correlate with their putative migration speed, suggesting a more complex nature of cellular processes that contribute to olfactory function. These results caution against comparing studies of olfactory function or neural precursors that use different strains of mice, and question the use of C57BL/6 mice as a "normal" strain or as transgenic background. Perhaps more importantly, the results point to an opportunity to identify genes that regulate olfactory function and neuroblast behavior.     

Sexual assault and other types of sexual harassment by workplace personnel: a comparison of antecedents and consequences

Although sexual assault by workplace personnel is widely viewed as a type of sexual harassment, little is known about whether these overlapping constructs may possess some unique characteristics. This article compares the theoretical antecedents and consequences of sexual assault by workplace personnel and other types of sexual harassment among 22,372 women employed in the U.S. military. Path analysis revealed that low sociocultural and organizational power are associated with an increased likelihood of both types of victimization. Organizational climate and job gender context are directly associated with sexual harassment but are only indirectly associated with sexual assault by workplace personnel. Both types of victimization are associated with a variety of negative outcomes, but the pattern of negative consequences differs.     

Costello syndrome: Clinical phenotype,genotype, and management guidelines

Costello syndrome (CS) is a RASopathy caused by activating germline mutations in HRAS. Due to ubiquitous HRAS gene expression, CS affects multiple organ systems and individuals are predisposed to cancer. Individuals with CS may have distinctive craniofacial features, cardiac anomalies, growth and developmental delays, as well as dermatological, orthopedic, ocular, and neurological issues; however, considerable overlap with other RASopathies exists. Medical evaluation requires an understanding of the multifaceted phenotype. Subspecialists may have limited experience in caring for these individuals because of the rarity of CS. Furthermore, the phenotypic presentation may vary with the underlying genotype. These guidelines were developed by an interdisciplinary team of experts in order to encourage timely health care practices and provide medical management guidelines for the primary and specialty care provider, as well as for the families and affected individuals across their lifespan. These guidelines are based on expert opinion and do not represent evidence‐based guidelines due to the lack of data for this rare condition.     

On the use of scaling and clustering in the study of semantic deficits

In the past decade, several studies have used scaling and clustering techniques to document semantic storage deficits in patients with Alzheimer's disease and in schizophrenia. In this article the authors argued that many of the conclusions drawn from these studies are unjustified by the data. They reviewed the methodology used in these studies and presented data from simulation studies to further investigate the validity of their conclusions. The authors elaborate on the criteria needed to exclude alternative accounts of the data and present empirical data from patients with Alzheimer's disease and normal control participants to demonstrate that analyses of the patients' proximity data do not provide unambiguous evidence for a generalized semantic storage deficit.     

Is auditory evoked potential augmenting/reducing affected by acute tryptophan depletion?

Several lines of evidence suggest that the auditory evoked potential (AEP) augmenting/reducing slope may serve as a biological marker of central serotonergic activity. According to Hegerl and Juckel (Biol. Psychiatry, 33, 1993, 173), reduced serotonergic activity is hypothesized to increase the slope of the AEP amplitude stimulus intensity function (ASF-slope). Hints for this hypothesis were investigated by employing the acute tryptophan depletion paradigm in 18 healthy females. A within-subject, placebo controlled double-blind cross over design was used for that purpose. Subjects ingested both a 50 g amino-acid drink with (placebo condition) and without tryptophan (depletion condition). With respect to the N1/P2-slope, test-retest reliability of a 1 week interval ranged between r=0.56 and 0.58 for the pre-ingestion baseline recording sessions. Affect was not altered by tryptophan depletion and not related to the ASF-slope. The comparison between placebo and depletion conditions did not reveal significant alterations of the ASF-slope, neither after 5 nor 6 h post-ingestion. Thus, the results do not support the assumption of the ASF-slope reflecting central serotonergic function.     

Response involvement in brain stimulation reward

The hypothesis that responding contributes to the reward value of brain stimulation was tested in two novel experimental paradigms. In the first experiment rats lever-presssed for rewarding brain stimulation during 90 sec periods. After each period the lever automatically retracted and experimenter-administered stimulation (EAS) was presented at the same rate and current parameters as during the self-stimulation (SS). The rats could demonstrate a preference for SS (vs EAS) by pressing a reset lever on the opposite wall of the test chamber. This action terminated the EAS and reinstated the SS-lever for an additional 90 sec. Results showed that the rats preferred to respond for stimulation than to have that same stimulation administered by the experimenter. This was true even when a signal preceded each train of EAS or when subjects had a great deal of previous EAS experience. In the second experiment conditioned taste preferences were observed following novel taste/SS pairings but not following novel taste/EAS pairings. The data from these two experiments suggest that responding contributes to the rewarding value of brain stimulation.     

Hypothalamic knife-cut hyperphagia and obesity in weanling rats

In previous reports weanling female rats fed a high-fat diet had a delayed response to hypothalamic knife cuts. In the present report similar cuts in similar rats fed a standard low fat diet became overweight without delay, suggesting that dietary fat is a critical variable in juvenile onset obesity. Adult rats given knife-cuts comparable to those in the weanlings gained weight far more rapidly and achieved higher weights than did those cut as weanlings, suggesting that appetite modulating axons can develop after weaning. Finally, group vs single housing did not influence the age of onset or the magnitude of knife-cut obesity.     

The projection of the temporal retina in rats,studied by retrograde transport of horseradish peroxidase

Summary Horseradish peroxidase (HRP) was injected unilaterally into the lateral geniculate nucleus or tectum, or both, in 26 hooded rats in order to mark the exact extent of the retina from which uncrossed optic axons arise. This region occupied about a quarter of the retina, in the temporal periphery, following thalamic injections, but a much smaller region following tectal injections. By comparing the proportions of HRP positive neurones in nasal and temporal retinae of both eyes it was shown that: (1) within the region supplying uncrossed axons the majority of the ganglion cells nevertheless project contralaterally, (2) a large proportion of the ganglion cells from the temporal crescent project bilaterally, which does not occur from the remainder of the retina, (3) ganglion cells of all sizes contribute to both ipsilateral and contralateral projections. The results also support earlier suggestions that the smallest neurones in the ganglion cell layer do not send an axon into the brain, and are therefore not ganglion cells     

Psychotherapy for depression: current and future directions in research, theory, practice and public policy

This article is based on a symposium held at the 1998 Annual Meeting of Society for Psychotherapy Research (Snow Bird, Utah). Recognized experts addressed current and future directions in psychotherapy for depression from the perspectives of process and outcome research, basic research, theoretical models, clinical practice and training, and public policy. The specific issues discussed at the symposium included the strengths and limitations of major forms of psychotherapy; the therapeutic factors common and unique to different approaches; the future viability of current theories of depression; the role of treatment manuals in clinical practice and training; the development of new interventions based on basic research; and the priorities that should guide federal funding.