Sporadic pemphigus foliaceus and class II human leucocyte antigen allele associations in the white British and Indo-Asian populations in the UK.

BACKGROUND: Pemphigus foliaceus (PF) has both genetic and environmental susceptibility factors. Current data on human leucocyte antigen (HLA) in patients with sporadic PF are limited. AIM: To better define the distribution of HLA alleles in patients with PF in the UK. METHODS: We recruited 36 patients [26 of white British (WB) descent, 10 of Indo-Asian (IA) descent] with PF who were living in the UK and 159 ethnically matched normal controls, and analysed their class II HLA DRB1 and DQB1 allele distribution. RESULTS: There was an increased frequency of DRB1*1404 in association with DQB1*0503 in IA patients with PF. The DRB1*04 allele group as a whole had an increased frequency (P < 0.001) in the WB patient group compared with controls. The alleles contributing to this significance were DRB1*0401 (P = 0.03) and DRB1*0404 (P < 0.01). CONCLUSION: This is the largest HLA association study in sporadic PF from the UK to date. There appears to be a difference in PF susceptibility alleles between WB and IA patients, highlighting the importance of racial variation in genetic susceptibility to disease development.

Maternal depressive symptoms and early childhood cognitive development: a meta-analysis.

BACKGROUND: Previous findings have been mixed regarding the relationship between maternal depressive symptoms and child cognitive development. The objective of this study was to systematically review relevant literature and to perform a meta-analysis. METHOD: Three electronic databases (PubMed, EMBASE, PsycINFO) were searched. Initial screening was conducted independently by two reviewers. Studies selected for detailed review were read in full and included based on a set of criteria. Data from selected studies were abstracted onto a standardized form. Meta-analysis using the inverse variance approach and random-effects models was conducted. RESULTS: The univariate analysis of 14 studies revealed that maternal depressive symptoms are related to lower cognitive scores among children aged ⩽56 months (Cohen's d = -0.25, 95% CI -0.39 to -0.12). The synthesis of studies controlling for confounding variables showed that the mean cognitive score for children 6-8 weeks post-partum whose mothers had high depressive symptoms during the first few weeks postpartum was approximately 4.2 units lower on the Mental Developmental Index (MDI) of the Bayley Scales of Infant and Toddler Development (BSID) compared with children with non-symptomatic mothers (B̂ = -4.17, 95% CI -8.01 to -0.32). CONCLUSIONS: The results indicated that maternal depressive symptoms are related to lower cognitive scores in early infancy, after adjusting for confounding factors. An integrated approach for supporting child cognitive development may include program efforts that promote maternal mental health in addition to family economic wellbeing, responsive caregiving, and child nutrition.

Prognostic factors in pemphigus vulgaris and pemphigus foliaceus.

BACKGROUND: Pemphigus typically has a chronic course, although there is great variability in disease duration (DD) and time taken to disease remission (DR) between individuals with the disease. The reasons for this are unclear. OBJECTIVES: To explore the prognostic influence of epidemiological, clinical, immunological and genetic factors on disease course and remission in pemphigus vulgaris (PV) and pemphigus foliaceus (PF). METHODS: This was a retrospective study of patients with PV and PF, recruited from a single UK centre. Direct and indirect immunofluorescence and enzyme-linked immunosorbent assay studies for antidesmoglein (Dsg) antibodies were used to assess immunological factors. Polymerase chain reaction with sequence specific primers (PCR-SSP) was used to assess the Class II human leukocyte antigen status of patients. Prognostic endpoints investigated were time to initial first DR and total DD. RESULTS: Ninety-five patients were recruited (79 PV and 16 PF). Patients of Indo-Asian origin were significantly associated with longer DD than White-British patients (P = 0.029). In addition, younger age at onset was associated with a worse prognosis in terms of DD: the mean age at presentation of patients with DD of < 5 years was 49 years (SEM = 3.4) compared with 40 years (SEM = 1.9) in those with DD > 5 years (P = 0.039). A higher initial intercellular antibody titre on normal human skin substrate was associated with a greater time to initial DR (P = 0.007) and high anti-Dsg 3 levels at baseline were associated with a longer total DD (P = 0.03). CONCLUSIONS: Ethnic group, age at presentation, initial intercellular antibody titre and initial Dsg 3 antibody levels all had a significant impact on prognosis of pemphigus.

Pulsed intravenous cyclophosphamide and methylprednisolone therapy in refractory pemphigus.

BACKGROUND: Pemphigus is a rare autoimmune blistering disorder. The mainstay of current treatment is high-dose oral corticosteroid therapy in combination with a steroid-sparing agent. Adjuvant therapy is important for disease control and to reduce the iatrogenic effects of oral prednisolone. Pulsed therapy with intravenous methylprednisolone and cyclophosphamide (PPC) has been shown to be an effective treatment but there are currently few data on its use in patients who have failed to respond to conventional immunosuppression. OBJECTIVES: To report the clinical and immunological responses of 21 patients with pemphigus refractory to prednisolone and azathioprine or mycophenolate mofetil treated in our department with a standard protocol of monthly PPC. METHODS: Patients with pemphigus were identified who had undergone PPC therapy during the period between 1997 and 2006. Initial clinical severity and response to treatment was assessed. In addition, change in intercellular antibody titres and desmoglein 1 and 3 antibodies to PPC therapy was also recorded. RESULTS: Of the 21 patients treated, seven had an excellent response, two a good response, five a moderate response, six a minimal response and one patient had no clinical response. Four patients achieved complete clinical remission and the number of pulses for these patients varied between 11 and 22. We observed significant reductions in indirect immunofluorescence titres for normal human skin substrate (P = 0.0078) and antidesmoglein 1 and 3 autoantibody levels (P = 0.007 and P = 0.0085, respectively) from pre-PPC therapy to 1 year after the last pulse. All patients were able to reduce their prednisolone dose from a pre-pulsing median dose of 40-10 mg at the last pulse with a median dose reduction of 66% (P < 0.001). The most common adverse effect was transient lymphopenia (12 patients); nonlife-threatening sepsis (seven patients) and premature ovarian failure (two patients) also occurred. CONCLUSIONS: PPC can be an effective treatment for refractory pemphigus but its adverse effects should be considered prior to therapy and closely monitored in patients on treatment.

Biochemical and immunological analyses of cytoskeletal domains of neurons.

We have used cultured sympathetic neurons to identify microtubule proteins (tubulin and microtubule-associated proteins [MAPs]) and neurofilament (NF) proteins in pure preparations of axons and also to examine the distribution of these proteins between axons and cell bodies + dendrites. Pieces of sympathetic ganglia containing thousands of neurons were plated onto culture dishes and allowed to extend neurites. Dendrites remained confined to the ganglionic explant or cell body mass (CBM), while axons extended away from the CBM for several millimeters. Axons were separated from cell bodies and dendrites by dissecting the CBM away from cultures, and the resulting axonal and CBM preparations were analyzed using biochemical, immunoblotting, and immunoprecipitation methods. Cultures were used after 17 d in vitro, when 40-60% of total protein was in the axons. The 68,000-mol-wt NF subunit is present in both axons and CBM in roughly equal amounts. The 145,000- and 200,000-mol-wt NF subunits each consist of several variants which differ in phosphorylation state; poorly and nonphosphorylated species are present only in the CBM, whereas more heavily phosphorylated forms are present in axons and, to a lesser extent, the CBM. One 145,000-mol-wt NF variant was axon specific. Tubulin is roughly equally distributed between CBM and axon-like neurites of explant cultures. MAP-1a, MAP-1b, MAP-3, and the 60,000-mol-wt MAP are also present in the CBM and axon-like neurites and show distribution patterns similar to that of tubulin. In contrast, MAP-2 was detected only in the CBM, while tau and the 210,000-mol-wt MAP were greatly enriched in axons compared to the CBM. In immunostaining analyses, MAP-2 localized to cell bodies and dendrite-like neurites, but not to axon-like neurites, whereas antibodies to tubulin and MAP-1b localized to all regions of the neurons. The regional differences in composition of the neuronal cytoskeleton presumably generate corresponding differences in its structure, which may, in turn, contribute to the morphological differences between axons and dendrites.

The phosphorylation of coated membrane proteins in intact neurons.

To complement studies that have demonstrated the prominent phosphorylation of a 50-kD coated vesicle polypeptide in vitro, we have evaluated the phosphorylation of coated membrane proteins in intact cells. A co-assembly assay has been devised in which extracts of cultured rat sympathetic neurons labeled with [32P]-Pi were combined with unlabeled carrier bovine brain coat proteins and reassembled coat structures were isolated by gradient centrifugation. Two groups of phosphorylated polypeptides, of 100-110 kD (pp100-110) and 155 kD (pp155) apparent molecular mass, were incorporated into reassembled coats. The neuronal pp100-110 are structurally and functionally related to the 100-110-kD component of the bovine brain assembly protein (AP), a protein complex that also contains 50-kD and 16.5-kD components and is characterized by its ability to promote the reassembly of clathrin coat structures under physiological conditions of pH and ionic strength (Zaremba, S. and J. H. Keen, 1983, J. Cell Biol., 97:1337-1348). The neuronal pp155 detected in reassembled coat structures was readily observable in total extracts of [32P]-Pi-labeled neurons dissolved in SDS-containing buffer. A bovine brain counterpart to the neuronal pp155 was also observed when brain coated vesicles were subjected to two-dimensional gel electrophoresis. Phosphoserine was the predominant phosphoaminoacid found in both the pp100 and pp155. A structural and functional counterpart to the 50-kD brain assembly polypeptide (AP50) was also identified in these neurons. Although the brain AP50 is prominently phosphorylated by an endogenous protein kinase in isolated coated vesicle preparations, the neuronal AP50 was not detectably phosphorylated in intact cells as assessed by two-dimensional non-equilibrium pH gradient gel electrophoresis of labeled cells dissolved directly in SDS-containing buffers. These results demonstrate that the bovine brain assembly polypeptides of 50 kD and 100-110 kD that we have previously described, as well as a novel 155-kD polypeptide reported here, have structural and functional counterparts in cultured neurons. They also indicate that phosphorylation of the 100-110-kD AP may be involved in the regulation of coated membrane structure and function. The extent of phosphorylation of the AP50 in intact cells and in isolated coated vesicles is strikingly different: it has been suggested that the latter process reflects an autophosphorylation reaction (Campbell C., J. Squicciarini, M. Shia, P. F. Pilch, and R. E. Fine, 1984, Biochemistry, 23:4420-4426).(ABSTRACT TRUNCATED AT 400 WORDS)

Newly assembled microtubules are concentrated in the proximal and distal regions of growing axons.

We have investigated the sites of microtubule (MT) assembly in neurons during axon growth by taking advantage of the relationship between the proportion of tyrosinated alpha-tubulin (tyr-tubulin) in MTs and their age. Specifically, young (newly assembled) MTs contain more tyr-tubulin than older (more long-lived) MTs. To quantify the relative proportion of tyr-tubulin in MTs, cultured rat sympathetic neurons were permeabilized under conditions that stabilize existing MTs and remove unassembled tubulin. The MTs were then double-stained with antibodies to tyr-tubulin (as a measure of the amount of tyr-tubulin in MTs) and to beta-tubulin (as a measure of total MT mass), using immunofluorescence procedures. Cells were imaged with a cooled charge-coupled device camera and the relative proportion of tyr-tubulin in the MTs was quantified by computing the ratio of the tyr-tubulin fluorescence to the beta-tubulin fluorescence using a novel application of digital image processing and analysis techniques. The amount of tyr-tubulin in the MTs was highest in the cell body and at the growth cone; peak ratios in these two regions were approximately 10-fold higher than for the axon shaft. Moving out from the cell body into the axon, the tyr-tubulin content declined over an average distance of 40 microns to reach a constant low value within the axon shaft and then rose again more distally, over an average distance of 110 microns, to reach a peak at the growth cone (average axon length = 358 microns). These observations indicate that newly assembled MTs are concentrated in the proximal and distal regions of growing axons and therefore that the cell body and growth cone are the most active sites of MT assembly dynamics in neurons that are actively extending axons.

Microtubule-associated proteins of neurons.

Microtubule-associated proteins (MAP) have been identified in cultures of rat sympathetic neurons. In all of the experiments performed here, the cultures consisted of greater than 97% neurons. 26 proteins were identified in these neuronal cultures that (a) remained associated with cytoskeletons prepared with a Triton X-100-containing microtubule-stabilizing buffer, (b) were released from such cytoskeletons by incubation in microtubule-depolymerizing buffers, (c) were not detected in cytoskeletons prepared from cultures depleted of microtubules by treatment with podophyllotoxin, and (d) co-cycled with rat brain microtubule proteins. We conclude that these 26 proteins are associated with microtubules in sympathetic neurons. Two of these proteins have molecular weights of approximately 30,000 and isoelectric points of approximately 6.2; the rest of the proteins range in molecular weight from 60,000 to 76,000 and isoelectric point from 6.3 to 6.9. This latter group of MAPs was heat labile. Several other proteins in the neuronal cultures had the solubility properties and drug-lability expected of MAP. All of these proteins had apparent molecular weights greater than 200,000; one of these putative MAP co-migrated with rat brain MAP-1. We did not detect any putative MAP in these cultures that co-migrated with rat brain MAP-2. In isoelectric focusing-SDS PAGE, the 24 MAP with molecular weights of 60,000-76,000 appeared to comprise four distinct molecular weight classes. Each molecular weight class was in turn composed of several proteins that varied in isoelectric point. In peptide mapping experiments, the isoelectric variants of each molecular weight class gave rise to very similar peptide maps. These observations suggest that each molecular weight class consists of several closely related proteins. It was also determined that all except the most basic member of the four MAP classes could be phosphorylated in vivo, raising the possibility that differential phosphorylation contributed to the variation in the isoelectric points of the members of each MAP class. We performed pulse-chase experiments to further evaluate the contribution of posttranslational modification to the generation of the complex population of MAP in the molecular weight range of 60,000 to 76,000. In cultures labeled for 20 min, only the more basic members of each MAP class were detectably labeled, while in cultures labeled for 20 min and then chased for 220 min the more acidic members of the MAP classes became labeled.(ABSTRACT TRUNCATED AT 400 WORDS)

Slow components of axonal transport: two cytoskeletal networks.

We have identified two slowly moving groups of axonally transported proteins in guinea pig retinal ganglion cell axons (4). The slowest group of proteins, designated slow component a (SCa), has a transport rate of 0.25 mm/d and consists of tubulin and neurofilament protein. The other slowly transported group of proteins, designated slow components b (SCb), has a transport rate of 2-3 mm/d and consists of many polypeptides, one of which is actin (4). Our analyses of the transport kinetics of the individual polypeptides of SCa and SCb indicate that (a) the polypeptides of SCa are transported coherently in the optic axons, (b) the polypeptides of SCb are also transported coherently but completely separately from the SCa polypeptides, and (c) the polypeptides of SCa differ completely from those comprising SCb. We relate these results to our general hypothesis that slow axonal transport represents the movements of structural complexes of proteins. Furthermore, it is proposed that SCa corresponds to the microtubule-neurofilament network, and that SCb represents the transport of the microfilament network together with the proteins complexed with microfilaments.

Antigen-induced changes in lymphoid cell histones. 3. In vitro and in extract.

Previous papers in this series have reported an acute, transitory effect of antigens on lymphoid cell nuclei. In the previous reports the effect was related to a change in ammoniacal silver (A-S) stainability of smears and cryostat sections. The variable substrate was identified as histone. This paper reports the results of an extended series of studies of histone and chromatin extracts from thymus glands exposed to antigen in vivo and in vitro. The antigen effect on A-S stainability is demonstrable not only in vitro but also in chromatin fibers representing a DNA-histone complex. However, it is not demonstrable in isolated histone fractions. The inference is drawn that the antigen-induced alteration in A-S stainability is brought about not by any quantitative change in histone, but by a biologically significant shift in histone binding, perhaps to DNA. It is suggested that alteration in DNA-histone binding during gene activation may alter A-S stainability of histones.

Antigen-induced changes in lymphoid cell histones. IV. Changes in solubility of isolated chromatin.

In this study we have examined the solubility of deoxyribonucleoprotein (DNP) isolated from control and antigen-affected thymocytes. 2-M sodium chloride extracts containing the DNP of rat thymus glands were serially diluted. A comparison was made of the effect of dilution on fiber formation in the control and test series. Fiber formation is usually complete for the control material at a salt concentration between 0.63 and 0.57 M. The test material shows some fiber formation within this range. However, a significant portion of the DNP is precipitated at dilutions of 0.54-0.48 M. Ammoniacal silver (A-S) stains the control fibers a characteristic yellowish color. With the test material, those fibers formed within the control range tended to be stained yellowish brown by A-S, whereas those formed only after greater dilution stained blackish. These data, coupled with our previous observations on altered A-S staining, clearly demonstrate an antigen-induced physical and/or chemical alteration of the histone or histone-DNA complex of lymphoid cell chromatin.

Changes in the colchicine susceptibility of microtubules associated with neurite outgrowth: studies with nerve growth factor-responsive PC12 pheochromocytoma cells.

The PC12 line of nerve growth factor (NGF)-responsive rat pheochromocytoma cells was used as a model system to determine whether properties of microtubules change during neurite growth and maturation. In the absence of NGF, PC12 cells lack processes. After several days with NGF, PC12 cells begin extending neurites and, by 2-3 wk with NGF, PC12 cells have long (approximately 1 mm), highly branched neurites. We examined the effect of colchicine on microtubules of PC12 cells grown without NGF or with NGF for 1 or 21 d. PC12 cells grown under the various conditions were exposed to 50 microM colchicine for 1 or 6 h, and were then assayed for their content of polymerized tubulin using a biochemical assay. Microtubule levels in drug-treated cultures were compared to those in non-drug-treated control sister cultures. PC12 cells grown without NGF or with NGF for 1 d were depleted of MT by 1 h with colchicine. In contrast, microtubule levels in long-term NGF-treated cells exposed to colchicine for 6 h were reduced to only approximately 57% of those in control cells. Control experiments indicated that the observed differential susceptibility to colchicine was not due to differences in colchicine uptake or to the effects of colchicine on cell viability. These observations suggest that microtubules of PC12 cells grown without NGF or with NGF for 21 d differ in their properties. Such differences may be related to one or more of the changes in structure and/or motility that result from treatment with NGF.

Individual microtubules in the axon consist of domains that differ in both composition and stability.

We have explored the composition and stability properties of individual microtubules (MTs) in the axons of cultured sympathetic neurons. Using morphometric means to quantify the MT mass remaining in axons after various times in 2 micrograms/ml nocodazole, we observed that approximately 48% of the MT mass in the axon is labile, depolymerizing with a t1/2 of approximately 5 min, whereas the remaining 52% of the MT mass is stable, depolymerizing with a t1/2 of approximately 240 min. Immunofluorescence analyses show that the labile MTs in the axon are rich in tyrosinated alpha-tubulin, whereas the stable MTs contain little or no tyrosinated alpha-tubulin and are instead rich in posttranslationally detyrosinated and acetylated alpha-tubulin. These results were confirmed quantitatively by immunoelectron microscopic analyses of the distribution of tyrosinated alpha-tubulin among axonal MTs. Individual MT profiles were typically either uniformly labeled for tyrosinated alpha-tubulin all along their length, or were completely unlabeled. Roughly 48% of the MT mass was tyrosinated, approximately 52% was detyrosinated, and approximately 85% of the tyrosinated MTs were depleted within 15 min of nocodazole treatment. Thus, the proportion of MT profiles that were either tyrosinated or detyrosinated corresponded precisely with the proportion of MTs that were either labile or stable respectively. We also observed MT profiles that were densely labeled for tyrosinated alpha-tubulin at one end but completely unlabeled at the other end. In all of these latter cases, the tyrosinated, and therefore labile domain, was situated at the plus end of the MT, whereas the detyrosinated, and therefore stable domain was situated at the minus end of the MT, and in each case there was an abrupt transition between the two domains. Based on the frequency with which these latter MT profiles were observed, we estimate that minimally 40% of the MTs in the axon are composite, consisting of a stable detyrosinated domain in direct continuity with a labile tyrosinated domain. The extreme drug sensitivity of the labile domains suggests that they are very dynamic, turning over rapidly within the axon. The direct continuity between the labile and stable domains indicates that labile MTs assemble directly from stable MTs. We propose that stable MTs act as MT nucleating structures that spatially regulate MT dynamics in the axon.

Regulation of microtubule composition and stability during nerve growth factor-promoted neurite outgrowth.

We have used the nerve growth factor (NGF)-responsive line of PC12 pheochromocytoma cells as a model system to study microtubule specializations associated with neurite outgrowth. PC12 cells treated with NGF cease proliferating and extend neurites. Long-term NGF treatment results in a two- to threefold increase in the proportion of total cellular tubulin that is polymerized in PC12 cells. The increase in this parameter first becomes apparent at 2-4 d with NGF and increases steadily thereafter. Several changes in microtubule-associated proteins (MAPs) of PC12 cells also occur after exposure to NGF. In immunoprecipitation assays, we observed the levels of MAP-2 to increase by at least several-fold after treatment with NGF. We also found that the compositions of three MAP classes with apparent Mr of 64K, 67K, and 80K are altered by NGF treatment. These MAPs, recently designated "chartins," are biochemically and immunologically distinct from the similarly-sized tau MAPs (Peng et al., 1985 Brain Res. 361: 200; Magendantz and Solomon, 1985 Proc. Natl. Acad. Sci. 82: 6581). In two-dimensional isoelectric focusing x SDS polyacrylamide gels, each chartin MAP class resolves into a set of proteins of similar apparent Mr but distinct pI. Peptide mapping analyses confirm that the isoelectric variants comprising each chartin MAP class are closely related in primary structure. Several striking differences in the composition of the chartin MAPs of PC12 cells grown with or without NGF were consistently observed. In particular, following longterm NGF treatment, the abundances of the more acidic variants of each chartin MAP class were markedly enhanced relative to the more basic members. This occurs without substantial changes in the abundance of each MAP class as a whole relative to total cell protein. The combined results of in vivo phosphorylation and peptide mapping experiments indicate that the NGF-inducible chartin MAP species are not primary translation products, but are generated posttranslationally, apparently by differential phosphorylation of other chartin MAPs. These observations suggest that NGF treatment of PC12 cells leads to changes in the posttranslational processing of the chartin MAPs. The time course of these changes closely resembles that for the increase in the proportion of cellular tubulin that is polymerized and for neurite outgrowth. One of the important events in the growth and stabilization of neurites appears to be the formation of microtubule bundles that extend from the cell body to the tips of the neurites.(ABSTRACT TRUNCATED AT 400 WORDS)

Changes in microtubule polarity orientation during the development of hippocampal neurons in culture.

Microtubules in the dendrites of cultured hippocampal neurons are of nonuniform polarity orientation. About half of the microtubules have their plus ends oriented distal to the cell body, and the other half have their minus ends distal; in contrast, microtubules in the axon are of uniform polarity orientation, all having their plus ends distal (Baas, P.W., J.S. Deitch, M. M. Black, and G. A. Banker. 1988. Proc. Natl. Acad. Sci. USA. 85:8335-8339). Here we describe the developmental changes that give rise to the distinct microtubule patterns of axons and dendrites. Cultured hippocampal neurons initially extend several short processes, any one of which can apparently become the axon (Dotti, C. G., and G. A. Banker. 1987. Nature [Lond.]. 330:477-479). A few days after the axon has begun its rapid growth, the remaining processes differentiate into dendrites (Dotti, C. G., C. A. Sullivan, and G. A. Banker. 1988. J. Neurosci. 8:1454-1468). The polarity orientation of the microtubules in all of the initial processes is uniform, with plus ends distal to the cell body, even through most of these processes will become dendrites. This uniform microtubule polarity orientation is maintained in the axon at all stages of its growth. The polarity orientation of the microtubules in the other processes remains uniform until they begin to grow and acquire the morphological characteristics of dendrites. It is during this period that microtubules with minus ends distal to the cell body first appear in these processes. The proportion of minus end-distal microtubules gradually increases until, by 7 d in culture, about equal numbers of dendritic microtubules are oriented in each direction. Thus, the establishment of regional differences in microtubule polarity orientation occurs after the initial polarization of the neuron and is temporally correlated with the differentiation of the dendrites.

Axonal transport: each major rate component reflects the movement of distinct macromolecular complexes.

The proteins of the three major rate components of axonal transport in guinea pig retinal ganglion cells were analyzed by one- and two-dimensional gel electrophoresis. Each rate component consisted of a different set of proteins that remained associated with each other during transport. This suggests that each rate component represents a distinct macromolecular complex and that these complexes may be definable organelles such as microtubules, microfilaments, and smooth endoplasmic reticulum. Thus, the transport of radiolabeled proteins in the axon reflects the movement of complete subcellular rather than the movement of individual proteins.

Cortisol reactivity and weight gain among adolescents who vary in prenatal drug exposure.

OBJECTIVE: Low inhibitory control is linked with weight gain among youth. Inhibitory problems are associated with disruption to the hypothalamic-pituitary-adrenal axis cortisol response. Increased cortisol predicts appetite and weight gain (though may be gender specific). This study hypothesized that cortisol reactivity explains the association between inhibition and weight gain while considering the moderating factors of early stressors to the hypothalamic-pituitary-adrenal axis (e.g. prenatal-drug exposure) and gender. METHODS: Adolescents with prenatal-drug exposure (n = 76) and non-exposed comparison adolescents (NE; n = 61) completed the Conner's Continuous Performance Test and provided salivary cortisol samples. BMI z-score were measured at the initial and 12-month follow-up evaluations. A bootstrapped moderated mediation analysis was conducted to test for conditional indirect effects of cortisol reactivity. RESULTS: Lower inhibition was associated with increased cortisol reactivity among youth who were NE, and increased cortisol reactivity was associated with weight gain among girls. Cortisol reactivity mediated the relation between inhibition and BMI z-score change for the girls in the group who was NE. CONCLUSION: Increased cortisol reactivity may play a mechanistic role in predicting weight gain among non-prenatally drug-exposed girls. Cortisol reactivity may be a biomarker for targeted interventions to improve biological regulation and ultimately health risk among girls.

The home environment and toddler physical activity: an ecological momentary assessment study.

BACKGROUND: Physical activity (PA) promotion/obesity prevention in toddlerhood should include home environments. OBJECTIVE: The aim of the study was to determine social/physical home environment factors associated with toddler PA using ecological momentary assessment (EMA, real-time data collection). METHODS: Low-income mother-toddler dyads were recruited and given a handheld EMA device (53 random beeps followed by social/physical environment survey over 8 d). Simultaneously, PA was assessed via accelerometry (data extracted 15 min before/after response, average activity counts per minute). Linear mixed-effects models were used, adjusting for toddler age, urban/suburban residence and time of day; covariate moderating effects were examined; within-subjects and between-subjects findings were reported. PA was hypothesized to be greater when toddlers are outside (vs. inside), children are nearby (vs. alone), toddlers are interacting with their mothers (vs. not) and TV is off (vs. on). RESULTS: The final count was 2454 EMA/PA responses for 160 toddlers (mean age 20 months, range 12-31; 55% male, 66% Black and 54% urban). Associations with PA include (within subjects) the following: outside location (212 additional counts min-1 ), children nearby (153 additional counts min-1 ) and interacting with mother (321 additional counts min-1 ), compared with alternatives. Age was moderated by outside location/PA association (within subjects), with 90 additional counts min-1 per 3-month age group outside vs. inside. No between-subjects or television/PA associations were found. CONCLUSIONS: Home environment factors were associated with PA, including outside location, children nearby and mother interaction. EMA is a novel method, allowing identification of contextual factors associated with behaviours in natural environments.

The basis of polarity in neurons.

It has been recognized since the very early studies on the cytology of vertebrate nervous systems that neurons produce two fundamentally different types of neurite, the axon and the dendrite. Contemporary studies using electron microscopy have defined in detail the many structural differences between axons and dendrites. Perhaps the best known of these differences concerns ribosomes and Golgi elements, which are present in dendrites, but are absent from axons. In this article, we present a possible explanation for this compartmentalization which is based on current understanding of organelle transport in cells and our recent demonstration of a fundamental difference in the organization of the microtubule-based transport systems that convey organelles into the axon or into the dendrite.