Mouse spinal cord in cell culture. I. Morphology and intrinsic neuronal electrophysiologic properties.

1. Reliable methods for establishing fetal mouse spinal cord (SC) and dorsal root ganglion (DRG) cells in long term (greater than 1 mo) dissociated cell cultures are described. These cells have been studied by morphologic and intracellular electrophysiologic techniques. 2. Cells studied electrophysiologically can be relocated after preparation for electron microscopy and examined in thin sections. The electron microscope shows that the surface membranes of these cells were directly accessible to the culture medium. The surfaces of SC cells were studded with synaptic boutons, whereas the DRG cell surfaces generally had none. 3. Current-voltage relationships and linear electrotonic properties of the neurons are described. Delayed and anomalous rectification were seen in both cell types. The length of SC cell dendrites was about one characteristic electrotonic length, while little or no contribution of the relatively sparse DRG cell processes was seen in the transient responses of the DRG cells. 4. Postspike and posttetanic hyperpolarizations in DRG cells were due to a surface membrane conductance increase; this was probably primarily an increase in K+ conductance. Post-activation hyperpolarization in SC cells was primarily due to activation of an electrogenic Na+ pump.     

Can the apparent adaptation of dopamine neurons’ mismatch sensitivities be reconciled with their computation of reward prediction errors?

According to modern reinforcement learning theories, midbrain dopamine (DA) neurons are part of an adaptive system within which learned expectations filter reward-related signals to enable computation of reward prediction errors (RPEs). Recent electrophysiological data on DA neuron responses to probabilistic reward schedules inspired the idea that DA neurons might be adapting their mismatch sensitivities to reflect variances of expected rewards. Taken literally as a mathematical hypothesis, this idea contradicts reinforcement learning theory, and most computational models of basal ganglia learning. Here, we report a qualitative mathematical derivation of the implications of a generic class of circuit models for learning to compute RPEs. This analysis and concordant circuit simulations, both of which predict DA neuron responses on probabilistic schedules, support a reinterpretation of the electrophysiological data that is fully compatible with the examined class of RPE models. This reinterpretation implies a novel and readily testable prediction.     

Sensitization to inhaled antigen by intratracheal instillation of dendritic cells

BACKGROUND: Airway dendritic cells (DCs) capture and present inhaled antigen. It is not known whether antigen presentation by DCs in the airways is sufficient to induce sensitization to inhaled antigen in vivo. METHODS: Rats were immunized by intratracheal instillation of ovalbumin (OVA) -pulsed bone marrow-derived DCs or macrophages and exposed 10 days later to a 30-min aerosol of OVA on 3 consecutive days. Total and differential cell counts and flow cytometry on bronchoalveolar lavage (BAL) fluid, airway histology and serum OVA-immunoglobulin (Ig) E levels were analysed 24 h after the last exposure. RESULTS: As few as 2 x 104 OVA-DC induced sensitization to inhaled OVA. The secondary response to OVA-aerosol consisted of an antigen-specific increase in the number of bronchoalveolar mononuclear cells, activated CD4-positive alphabeta-TCR T lymphocytes, neutrophils and few eosinophils. Peribronchial and perivascular mononuclear cell infiltrates were seen on histological analysis. There was no production of systemic OVA-IgE. Bone marrow-derived macrophages did not induce sensitization. CONCLUSION: Delivering antigen to the respiratory tract via professional antigen-presenting DCs sensitizes for a secondary response to inhaled antigen leading to airway inflammation. This model will prove very useful for studying the early events of sensitization to inhaled antigen using the respiratory route.     

Posttraumatic stress disorder among low-income women exposed to perinatal intimate partner violence

Women exposed to intimate partner violence (IPV) and other forms of lifetime trauma may be at risk for negative mental health outcomes including posttraumatic stress disorder (PTSD). The purpose of this study was to examine potential predictors of PTSD among low-income women exposed to perinatal IPV. This study analyzed baseline cross-sectional data from 239 low-income pregnant women in the USA who participated in a nurse home visitation intervention between 2006 and 2012 after reporting recent IPV. PTSD was assessed with the Davidson Trauma Scale (DTS) in which participants answer questions about the most disturbing traumatic event (MDTE) in their lifetime that affected them the week before the interview. In total, 40 % of the women were identified as having PTSD (DTS ≥40). PTSD prevalence significantly increased with age to nearly 80 % of women ages 30 and older (n?=?23). Age was also the strongest predictor of PTSD (p?<?0.001). Most participants (65 %) identified non-IPV-related traumas as their MDTEs. Psychological (94 %), physical (82 %), and sexual (44 %) violence were not significantly associated with PTSD status. Despite recent exposure to IPV, most participants identified other traumatic events as more disturbing than IPV-related trauma. Further, the risk for PTSD increased with age, suggesting that the cumulative effect of trauma, which may include IPV, increases the risk for PTSD over a lifetime. Implementing comprehensive screening for trauma during prenatal care may lead to the early identification and treatment of PTSD during pregnancy in a community setting.     

Pragmatism in modeling peer influence: dynamics,outcomes, and change processes

This paper reviews the model-building approach to developmental psychopathology as it applies to understanding the influence of peers on adolescent problem behavior. Considerable longitudinal evidence suggests that deviant peer involvement is prognostic of escalations in various forms of problem behavior, including substance use, delinquent behavior, and violence. Most convincing, however, are data from randomized intervention trials that show alarming iatrogenic effects for aggregating high-risk peers. This paper shows that intervention research can also clarify the role of parents in reducing deviant peer involvement. Results from a 4-year prevention trial are reported for a community sample of multiethnic middle school youth. Random assignment to family-centered services in a school Family Resource center produced reduced growth in deviant peer involvement. The extensiveness of the parenting intervention was correlated with reduced growth in deviant peer involvement, especially among high-risk youth. Findings are discussed with respect to developmental theory and the design of future intervention trials that clarify the role of adults in structuring the emerging adolescents' world of peers.     

Is multiple SNP testing in BRCA2 and BRCA1 female carriers ready for use in clinical practice? Results from a large Genetic Centre in the UK

BRCA1 and BRCA2 are major breast cancer susceptibility genes. Nineteen single nucleotide polymorphisms (SNPs) at 18 loci have been associated with breast cancer. We aimed to determine whether these predict breast cancer incidence in women with BRCA1/BRCA2 mutations. BRCA1/2 mutation carriers identified through the Manchester genetics centre between 1996 and 2011 were included. Using published odds ratios (OR) and risk allele frequencies, we calculated an overall breast cancer risk SNP score (OBRS) for each woman. The relationship between OBRS and age at breast cancer onset was investigated using the Cox proportional hazards model, and predictive ability assessed using Harrell's C concordance statistic. In BRCA1 mutation carriers we found no association between OBRS and age at breast cancer onset: OR for the lowest risk quintile compared to the highest was 1.20 (95% CI 0.82–1.75, Harrell's C = 0.54), but in BRCA2 mutation carriers the association was significant (OR for the lowest risk quintile relative to the highest was 0.47 (95% CI 0.33–0.69, Harrell's C = 0.59). The 18 validated breast cancer SNPs differentiate breast cancer risks between women with BRCA2 mutations, but not BRCA1. It may now be appropriate to use these SNPs to help women with BRCA2 mutations make maximally informed decisions about management options.     

Hoechst staining and exposure to UV laser during flow cytometric sorting does not affect the frequency of detected endogenous DNA nicks in abnormal and normal human spermatozoa

Controlling the sex of offspring by the separation of X and Y chromosome-bearing spermatozoa using flow cytometry has been reported as a clinical technique aiding prevention of X-linked diseases. Although this technique has resulted in several hundred normal births in animals and at least one human birth, there is still concern over its genetic safety due to the involvement of two potentially mutagenic agents: UV light and the fluorochrome dye, Hoechst 33342 (H33342). Human spermatozoa, particularly those considered abnormal, may be more likely to suffer DNA damage following exposure to mutagenic agents, compared with other mammalian species. The stability of normal fresh and decondensed human spermatozoa were examined after exposure to a range of levels of UV and H33342 staining, using an assay that detects endogenous nicks in the DNA of spermatozoa. The stability of abnormal and normal, fresh and frozen-thawed human spermatozoa was examined following UV laser, H33342 staining and flow cytometry treatments utilizing the same assay. There was an increase in the presence of endogenous nicks when spermatozoa were decondensed compared with fresh spermatozoa. There was no increase in the incidence of nicks in any group of spermatozoa after UV and fluorochrome exposure compared with controls without exposure.      

Modulation of disease severity of dystrophic epidermolysis bullosa by a splice site mutation in combination with a missense mutation in the COL7A1 gene

Dystrophic epidermolysis bullosa (EBD) is a clinically heterogeneous skin disorder, characterized by abnormal anchoring fibrils (AF) and loss of dermal-epidermal adherence. EBD has been linked to the COL7A1 gene at chromosome 3p21 which encodes collagen VII, the major component of the AF. Here we investigated two unrelated EBD families with different clinical phenotypes and novel combinations of recessive and dominant COL7A1 mutations. Both families shared the same recessive heterozygous 14 bp deletion at the exon-intron 115 boundary of the COL7A1 gene. The deletion caused in-frame skipping of exon 115 and the elimination of 29 amino acid residues from the pro-alpha1(VII) polypeptide chain. As a result, procollagen VII was not converted to collagen VII and the C-terminal NC-2 propeptide which is normally removed from the procollagen VII prior to formation of the anchoring fibrils was retained in the skin. All affected individuals also carried missense mutations in exon 73 of COL7A1 which lead to different glycine- to-arginine substitutions in the triple-helical domain of collagen VII. Combination of the deletion mutation with a G2009R substitution resulted in a mild phenotype. In contrast, combination of the deletion with a G2043R substitution led to a severe phenotype. The G2043R substitution was a de novo mutation which alone caused a mild phenotype. Thus, different combinations of dominant and recessive COL7A1 mutations can modulate disease activity of EBD and alter the clinical presentation of the patients.      

清除骨髓中癌细胞的磁性微球研究 II.聚苯乙烯磁性微球的研制

为制备能用于清除骨髓中癌细胞的磁性微球,首先合成了单分散、大粒径的多孔聚苯乙烯交联微球,借助微球多孔结构对其进行磁化。探讨了影响磁化效果的主要因素。为使其与单抗连接紧密,在微球表面聚合了一层聚丙烯醛膜,使其表面带上易与单抗反应的醛基。同时测定了所制微球的磁响应性。X-射线衍射证明磁性物质为γ-Fe₂O₃。     

Erythrocyte membrane proteins reactive with IgG (warm-reacting) anti- red blood cell autoantibodies: II. Antibodies coprecipitating band 3 and glycophorin A

In our initial immunochemical study of the red blood cell (RBC) membrane proteins targeted in 20 cases of warm-antibody autoimmune hemolytic anemia (AHA), RBC eluates of 6 patients mediated immunoprecipitation (IP) of both band 3 and glycophorin A (GPA). This dual IP pattern had previously been observed with murine monoclonal antibodies (MoAbs) against the high frequency blood group antigen, Wrb (Wright), suggesting that the Wrb epitope may depend on a band 3-GPA interaction. Earlier, anti-Wrb had been identified serologically as a prominent non-Rh specificity of AHA autoantibodies. In the present study, 6 autoantibody eluates immunoprecipitating band 3 and GPA from common Wr(b+) RBCs were retested, in parallel with murine anti-Wrb MoAbs, against very rare Wr(a+b-)En(a+)RBCs. One patient's autoantibodies were unreactive with the Wr(b-) RBCs by either IP or indirect antiglobulin test (IAT) and were judged to have "pure" anti- Wrb specificity. Two other patients' autoantibodies displayed both IP and serologic evidence for anti-Wrb as a major component in combination with one or more additional specificities. However, among 3 other patients whose autoantibodies coprecipitated band 3 and GPA, there was no reduction in IP or IAT reactivity with Wr(b-) RBCs in 2 and only slight reduction in the third. We conclude (1) that human anti-Wrb autoantibodies, like their murine monoclonal counterparts, coprecipitate band 3 and GPA from human RBCs; but (2) that not all antibodies with this IP behavior have anti-Wrb serologic specificity, as defined by this donor's Wr(b-) RBCs. The possibility of an additional (non-Wrb) RBC epitope dependent on a band 3-GPA interaction is raised.