Sema-1a Reverse Signaling Promotes Midline Crossing in Response to Secreted Semaphorins.

Commissural axons must cross the midline to form functional midline circuits. In the invertebrate nerve cord and vertebrate spinal cord, midline crossing is mediated in part by Netrin-dependent chemoattraction. Loss of crossing, however, is incomplete in mutants for Netrin or its receptor Frazzled/DCC, suggesting the existence of additional pathways. We identified the transmembrane Semaphorin, Sema-1a, as an important regulator of midline crossing in the Drosophila CNS. We show that in response to the secreted Semaphorins Sema-2a and Sema-2b, Sema-1a functions as a receptor to promote crossing independently of Netrin. In contrast to other examples of reverse signaling where Sema1a triggers repulsion through activation of Rho in response to Plexin binding, in commissural neurons Sema-1a acts independently of Plexins to inhibit Rho to promote attraction to the midline. These findings suggest that Sema-1a reverse signaling can elicit distinct axonal responses depending on differential engagement of distinct ligands and signaling effectors.

Carrier-envelope offset frequency stabilization in a femtosecond optical parametric oscillator without nonlinear interferometry.

By exploiting the correlation between changes in the wavelength and the carrier-envelope offset frequency (f(CEO)) of the signal pulses in a synchronously pumped optical parametric oscillator, we show that f(CEO) can be stabilized indefinitely to a few megahertz in a 333 MHz repetition-rate system. Based on a position-sensitive photodiode, the technique is easily implemented, requires no nonlinear interferometry, has a wide capture range, and is compatible with feed-forward techniques that can enable f(CEO) stabilization at loop bandwidths far exceeding those currently available to OPO combs.

Psychological trauma in patients with psychogenic nonepileptic seizures: trauma characteristics and those who develop PTSD.

OBJECTIVES: The first objective of this study was to examine and describe the demographic, psychiatric, and trauma characteristics of our sample with PNESs as a whole. Subsequently, a comparison between traumatized and nontraumatized patients with PNESs was performed with regard to descriptive and trauma characteristics and general psychopathology symptoms. Lastly, we analyzed the predictive value in distinguishing patients with "likely" vs. "not likely" PTSD utilizing a model derived from our patients' psychometric test results. METHODS: We collected and tallied demographic and psychiatric information and trauma characteristics on 61 patients with PNESs who had confirmed or denied having experienced trauma in their lifetime. We then studied this group with the Trauma Symptom Inventory-2 (TSI-2) and the Minnesota Multiphasic Personality Inventory-2RF (MMPI-2RF). Traumatized patients were subsequently classified as "PTSD likely" and "PTSD not likely" based on TSI-2 criteria and compared on demographic, psychiatric, and trauma characteristics and MMPI-2RF scores. RESULTS: Our study revealed that 45 out of 61 (73.8%) patients reported experiencing at least one traumatic event in their lifetime. Approximately 40% reported physical or sexual abuse followed in percentage size by loss of a significant other, psychological abuse, witnessing the abuse of others, and medical trauma. Traumatized vs. nontraumatized and "PTSD likely" and "PTSD not likely" patients differed significantly on several clinical variables, as well as MMPI-2RF scores. Scores from TSI-2 produced a model that accurately predicted "no PTSD" in 21/26 (80.77%) subjects who denied a history of PTSD and "PTSD" in 5/6 subjects (83.33%) who endorsed a history of PTSD. CONCLUSION: This study showed that overall exposure to psychological trauma is much more prevalent in patients with PNESs than in the general population with an inordinately high exposure to sexual and physical abuse as well as a variety of other types of abuse. Psychopathology was identified in the group with PNESs as a whole with discrete distinctions in clinical symptoms and characteristics of the traumatized as well as the "PTSD likely" subgroups. These findings contribute useful information in understanding intragroup differences in what is increasingly appearing to be a heterogeneous psychiatric condition composed of distinguishable subgroups.

Stress coping strategies in patients with psychogenic non-epileptic seizures and how they relate to trauma symptoms, alexithymia, anger and mood.

PURPOSE: The purpose of the present study was to assess stress coping strategies employed by patients with psychogenic non-epileptic seizures (PNES) and determine whether these approaches were associated with other psychopathological features. Ineffective stress coping strategies can have a variety of unhealthy consequences fueling psychopathology just as psychopathology can also have an impact on stress coping. Because of this, the study of stress coping has the potential to inform our understanding of the PNES condition and underscore a potential target for psychological treatment. METHODS: Eighty-two consecutive patients with PNES were studied using the Coping Inventory for Stressful Situations (CISS). The CISS is a self-rating coping strategies scale that has three main subscales (Task-Oriented, Emotion-Focused, and Avoidance-Oriented). Other psychological variables that were thought to potentially influence the chosen coping mechanisms including alexithymia, symptoms of post-traumatic stress disorder, anger expression and select scales from the Minnesota Multiphasic Personality Inventory 2-RF (MMPI 2-RF) were also evaluated. RESULTS: Fifty patients (60.9%) endorsed using at least one coping strategy that was 1.5 standard deviations or more away from the normal adult mean. Over 30% of the participants endorsed using elevated Emotion-Focused coping strategies (T score ≥ 65), and just over 25% endorsed underusing Task-Oriented coping strategies (T score ≤ 35). Elevations in avoidance strategies were endorsed by only 15.9% of the respondents. ANOVA comparing T scores between the coping strategies was significant (F=13.4, p=.0001) with a significantly lower Task-Oriented strategy than Emotion-Focused (p=.001) and Avoidance (p=.005) strategies. Patients with high scores of Emotion-Focused coping strategies also had significantly high scores on diverse psychopathology factors including elevations on depressive mood, intrusive experiences, anger state, and general anger scores. In contrast, those who used Task-Oriented strategies and who used Avoidance-Focused strategies had less psychopathology including low positive emotion scores (RC2). CONCLUSION: Nearly one-third of patients with PNES tended to use the less effective Emotion-Oriented coping strategies and one fourth reported underusing the more effective Task-focused strategies. Substantial differences were noted between coping strategies with a significantly lower Task-Oriented strategy than Emotion-Focused and Avoidance strategies. In addition, high Emotion-Focused coping was seen in patients with underlying psychological symptoms that were not observed in other coping strategies. This information supports the relevance of assessing stress coping in patients with PNES because it allows the identification of useful behavioral targets for the psychotherapist.

Expression of human glutathione S-transferase P1 confers resistance to benzo[a]pyrene or benzo[a]pyrene-7,8-dihydrodiol mutagenesis, macromolecular alkylation and formation of stable N2-Gua-BPDE adducts in stably transfected V79MZ cells co-expressing hCYP1A1.

Transgenic cell lines were constructed to study dynamic competition between activation versus detoxification of benzo[a]pyrene (B[a]P) and its metabolites. Transfected V79MZ cells expressing human cytochrome P4501A1 (hCYP1A1) alone, or expressing hCYP1A1 in combination with human glutathione S-transferase P1 (hGSTP1), were used to determine how effectively GST protects against macromolecular damage or mutagenicity of B[a]P or its enantiomeric dihydrodiol metabolites (+)-benzo[a]pyrene-7,8-dihydrodiol [(+)B[a]P-7,8-diol] and (-)-benzo[a]pyrene-7,8-dihydrodiol [(-)-B[a]P-7,8-diol]. Mutagenicity of B[a]P at the hprt locus was dose- and time-dependent in cells that expressed hCYP1A1. Mutagenicity was reduced in cells further modified to co-express hGSTP1. Dose-response and time-course studies indicated that mutagenicity was reduced up to 3-fold by hGSTP1 expression, compared with cells expressing hCYP1A1 alone. Mutagenicity induced by the B[a]P 7,8-dihydrodiols was also dose-dependent, and was reduced 2- to 5-fold by hGSTP1. Expression of hGSTP1 reduced B[a]P adducts in total cellular macromolecules by 3.8-fold, which correlated with the reduction in B[a]P mutagenicity and with reduction in the formation of the proximate metabolite B[a]P 7,8-dihydrodiols from B[a]P. However, measurement of total B[a]P metabolites bound to DNA isolated from cells incubated with [3H]-B[a]P revealed only 12, 33 and 24% reduction at 12, 24 and 48 h, respectively, by GSTP1 expression. Nevertheless, (32)P-post-labeling analysis demonstrated nearly total prevention of the known B[a]P-DNA adduct, N2-guanine-benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), in cells co-expressing hGSTP1. This adduct, thought to be the most mutagenic of the stable B[a]P adducts, accounts for 15% or less of the total DNA adducts observed. These results indicate that the reduction in hCYP1A1-mediated B[a]P mutagenesis by hGSTP1 is probably largely due to prevention of the N2-guanine-BPDE adduct. However, the significant fraction (30-40%) of this mutagenesis and the majority of the total DNA binding that are not prevented together suggest formation by hCYP1A1 of a subset of mutagenic metabolites of B[a]P that are not effectively detoxified by hGSTP1.

Marsupial BRCA1: conserved regions in mammals and the potential effect of missense changes.

More than half of the reported missense changes in the breast cancer susceptibility protein BRCA1 occur in exon 11, but none has been clearly identified as disease associated and only 28 are designated 'probable' neutral polymorphisms. Previously, in a comparison of sequences from 57 eutherian mammal species, we found seven 'highly conserved regions' between amino acids 282 and 1103, and identified 38 missense changes as likely to disrupt gene function. These conserved regions were also present in birds and amphibians and included only six of the mutations predicted to affect function. In this new analysis, we hypothesized that using 37 ancestral sequences derived from the 57 GenBank sequences and including eight marsupial sequences would allow us to identify regions unique to mammals and refine our predictions of disease-associated missense changes. We identified 13 conserved regions, three of which appear to be unique to mammals, and 21 likely disease-associated missense changes, 11 of which occur in conserved regions. Seven regions identified in this analysis, including the three found only in mammalian sequences, and nine missense changes predicted to affect function are in the putative STAT1-interaction domain, suggesting that the role of STAT1 in immune response is important to mammary function. The reduction in the number of missense changes predicted to be disease associated and the identification of conserved regions specific to mammals can facilitate the further study of the role of missense changes in BRCA1-associated breast cancers.

Understanding missense mutations in the BRCA1 gene: an evolutionary approach.

The role of missense changes in BRCA1 in breast cancer susceptibility has been difficult to establish. We used comparative evolutionary methods to identify potential functionally important amino acid sites in exon 11 and missense changes likely to disrupt gene function, aligning sequences from 57 eutherian mammals and categorizing amino acid sites by degree of conservation. We used Bayesian phylogenetic analyses to determine relationships among orthologs and identify codons evolving under positive selection. Most conserved residues occur in a region with the highest concentration of protein-interacting domains. Rapidly evolving residues are concentrated in the RAD51-interacting domain, suggesting that selection is acting most strongly on the role of BRCA1 in DNA repair. Investigation of the functional role of missense changes in breast-cancer susceptibility should focus on 38 missense changes in conserved and 3 in rapidly evolving regions of exon 11.

Loss of genetic diversity in sea otters (Enhydra lutris) associated with the fur trade of the 18th and 19th centuries.

Sea otter (Enhydra lutris) populations experienced widespread reduction and extirpation due to the fur trade of the 18th and 19th centuries. We examined genetic variation within four microsatellite markers and the mitochondrial DNA (mtDNA) d-loop in one prefur trade population and compared it to five modern populations to determine potential losses in genetic variation. While mtDNA sequence variability was low within both modern and extinct populations, analysis of microsatellite allelic data revealed that the prefur trade population had significantly more variation than all the extant sea otter populations. Reduced genetic variation may lead to inbreeding depression and we believe sea otter populations should be closely monitored for potential associated negative effects.

Phylogeography of endemic ermine (Mustela erminea) in southeast Alaska.

The North Pacific Coast (NPC) of North America is a region of high mammalian endemism, possibly due to its highly fragmented landscape and complex glacial history. For example, four island and one mainland subspecies of ermine, Mustela erminea, have been described as endemic to southeast Alaska alone. To better understand the role of past climatic change in generating diversity in the region, we examined DNA sequence variation in the mitochondrial cytochrome b gene of 210 ermine from across North America, with an emphasis on Alaska and British Columbia. We found three distinct (1.5-3.6% uncorrected 'p') lineages of ermine, all of which occur in southeast Alaska. One lineage includes a southeast Alaska endemic and specimens from Alaska (outside of southeast) and Eurasia. A second lineage includes two southeast Alaskan endemics and ermine from western Canada and the coterminous United States. The close relationships of these purported endemics to ermine outside of southeast Alaska suggest that they colonized the region from Beringian and southern glacial refugia, respectively, following deglaciation of the NPC. The third lineage appears restricted to the Prince of Wales Island complex in southeast Alaska (two subspecies) and Graham Island (Haida Gwaii), British Columbia. This restricted distribution suggests that these populations may be derived from relicts that persisted in a coastal refugium during the Wisconsin glaciation. Studies of nuclear genes and adaptive morphological evolution are necessary to further explore discrepancies between the geographical pattern of differentiation based on mtDNA and the existing subspecific taxonomy based on morphology.