87 research outputs found
APP controls the formation of PI(3,5)P2 vesicles through its binding of the PIKfyve complex
Phosphoinositides are signalling lipids that are crucial for major signalling events as well as established regulators of membrane trafficking. Control of endosomal sorting and endosomal homeostasis requires phosphatidylinositol-3-phosphate (PI(3)P) and phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2), the latter a lipid of low abundance but significant physiological relevance. PI(3,5)P2 is formed by phosphorylation of PI(3)P by the PIKfyve complex which is crucial for maintaining endosomal homeostasis. Interestingly, loss of PIKfyve function results in dramatic neurodegeneration. Despite the significance of PIKfyve, its regulation is still poorly understood. Here we show that the Amyloid Precursor Protein (APP), a central molecule in Alzheimer’s disease, associates with the PIKfyve complex (consisting of Vac14, PIKfyve and Fig4) and that the APP intracellular domain directly binds purified Vac14. We also show that the closely related APP paralogues, APLP1 and 2 associate with the PIKfyve complex. Whether APP family proteins can additionally form direct protein–protein interaction with PIKfyve or Fig4 remains to be explored. We show that APP binding to the PIKfyve complex drives formation of PI(3,5)P2 positive vesicles and that APP gene family members are required for supporting PIKfyve function. Interestingly, the PIKfyve complex is required for APP trafficking, suggesting a feedback loop in which APP, by binding to and stimulating PI(3,5)P2 vesicle formation may control its own trafficking. These data suggest that altered APP processing, as observed in Alzheimer’s disease, may disrupt PI(3,5)P2 metabolism, endosomal sorting and homeostasis with important implications for our understanding of the mechanism of neurodegeneration in Alzheimer’s disease
Hyperresponsiveness to inhaled but not intravenous methacholine during acute respiratory syncytial virus infection in mice
BACKGROUND: To characterise the acute physiological and inflammatory changes induced by low-dose RSV infection in mice. METHODS: BALB/c mice were infected as adults (8 wk) or weanlings (3 wk) with 1 × 10(5 )pfu of RSV A2 or vehicle (intranasal, 30 μl). Inflammation, cytokines and inflammatory markers in bronchoalveolar lavage fluid (BALF) and airway and tissue responses to inhaled methacholine (MCh; 0.001 – 30 mg/ml) were measured 5, 7, 10 and 21 days post infection. Responsiveness to iv MCh (6 – 96 μg/min/kg) in vivo and to electrical field stimulation (EFS) and MCh in vitro were measured at 7 d. Epithelial permeability was measured by Evans Blue dye leakage into BALF at 7 d. Respiratory mechanics were measured using low frequency forced oscillation in tracheostomised and ventilated (450 bpm, flexiVent) mice. Low frequency impedance spectra were calculated (0.5 – 20 Hz) and a model, consisting of an airway compartment [airway resistance (Raw) and inertance (Iaw)] and a constant-phase tissue compartment [coefficients of tissue damping (G) and elastance (H)] was fitted to the data. RESULTS: Inflammation in adult mouse BALF peaked at 7 d (RSV 15.6 (4.7 SE) vs. control 3.7 (0.7) × 10(4 )cells/ml; p < 0.001), resolving by 21 d, with no increase in weanlings at any timepoint. RSV-infected mice were hyperresponsive to aerosolised MCh at 5 and 7 d (PC(200 )Raw adults: RSV 0.02 (0.005) vs. control 1.1 (0.41) mg/ml; p = 0.003) (PC(200 )Raw weanlings: RSV 0.19 (0.12) vs. control 10.2 (6.0) mg/ml MCh; p = 0.001). Increased responsiveness to aerosolised MCh was matched by elevated levels of cysLT at 5 d and elevated VEGF and PGE(2 )at 7 d in BALF from both adult and weanling mice. Responsiveness was not increased in response to iv MCh in vivo or EFS or MCh challenge in vitro. Increased epithelial permeability was not detected at 7 d. CONCLUSION: Infection with 1 × 10(5 )pfu RSV induced extreme hyperresponsiveness to aerosolised MCh during the acute phase of infection in adult and weanling mice. The route-specificity of hyperresponsiveness suggests that epithelial mechanisms were important in determining the physiological effects. Inflammatory changes were dissociated from physiological changes, particularly in weanling mice
Deliberate self-harm and attachment: mediating and moderating roles of depression, anxiety, social support and interpersonal problems among Pakistani school going adolescents
Introduction: In Pakistan there is dearth of research on deliberate self-harm (DSH) and
its predictors among adolescents. While the lack of research in Pakistan can be partly
attributed to the sacrilegious status, criminalization and stigmatization attached to DSH, it
is also an attribute of paucity of Urdu versions of the standardized psychological
instruments. Previous research in developed countries has indicated that attachment theory
can be used as a useful framework to understand the development of austere
psychopathologies like DSH, as well as for studying pathways of interaction of
interpersonal and intrapersonal factors of psychopathologies. In this study, standardized
psychological instruments are translated into Urdu language as a first step. These
instruments are then used to study pathways of interaction of interpersonal and
intrapersonal factors of DSH, conceptualized within attachment framework.
Method: The study was conducted in two steps. In step 1, Youth Health Risk Behavior
Survey (YHRB), Inventory of Interpersonal Problems-32 (IIP-32) and Significant Others
Scale (SOS), were translated into Urdu language. Along with these scales, Urdu translated
versions of Hospital Anxiety and Depression Scale (HADS), Adolescent Relationship
Scales Questionnaire (ARSQ), Life Events scale (LES) from CASE questionnaire and
Family Affluence Scale-II (FAS-II) were reviewed for accuracy of translation through
expert judgement and psychometric evaluation. Secondly, a cross sectional survey was
conducted with 1290 adolescents (10 - 19 years age) using the translated Urdu versions of
the instruments and demographic pro forma. Structural equation modelling was used to
study the pathways of associations between predictors of DSH.
Results: The extensive process of translation resulted in establishment of semantic,
content, technical and construct equivalence of the translated instruments with the original
English versions. Multiple imputation was performed to account for missing values in
SPSS 20. Important structural adaptations were made in the scales based on factor analyses
conducted in M plus. After modifications, all scales showed satisfactory CFI (≥ 0.90) and
RMSEA (≤ 0.06). Results of the survey indicated that the prevalence of DSH (with, without
and ambivalent suicidal intentions) was 7%. Two SEM models were constructed involving
both mediation and moderation pathways. Results of Model 1 showed association of
attachment with DSH was double mediated by social support, depression and anxiety.
Model 2 also confirmed association of attachment with DSH with double mediation
through relationship style problems, depression and anxiety. In order to understand the
contextual picture of the concepts studied in this research both SEM models were also
constructed by controlling for demographic factors. This resulted in confirming age,
gender and family affluence as significant contributors but with very small effects.
Discussion and conclusion: In the present study translation of the instruments helped in
building a reservoir for future research. The results of translation and validation of
instruments indicated that cultural differences, language needs and age must be accounted
for while using standardized psychological instruments. Taking into consideration specific
cultural and demographic background of Pakistan, this study also confirms the key role of
attachment in influencing interaction of predictors of DSH. It is suggested that
intrapersonal and interpersonal factors are influential points of intervention for designing
clinical, school and community based awareness and prevention programs for DSH. The
thesis also discusses the implications for policy guidelines along with recommendations
for future research and other applications of the study
Financial and Economic Well-Being: A Decade Review from Journal of Family and Economic Issues
Evidence for an association between suicide and religion: a 33-year retrospective autopsy analysis of suicide by hanging during the month of Ramadan in Istanbul
- …