64 research outputs found

    Determinants of vaccination coverage and consequences for rabies control in Bali, Indonesia

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    Maintaining high vaccination coverage is key to successful rabies control, but mass dog vaccination can be challenging and population turnover erodes coverage. Declines in rabies incidence following successive island-wide vaccination campaigns in Bali suggest that prospects for controlling and ultimately eliminating rabies are good. Rabies, however, has continued to circulate at low levels. In the push to eliminate rabies from Bali, high coverage needs to be maintained across all areas of the island. We carried out door-to-door (DTD) questionnaire surveys (n = 10,352 dog-owning households) and photographic mark–recapture surveys (536 line transects, 2,597 observations of free-roaming dogs) in 2011–2012 to estimate dog population sizes and assess rabies vaccination coverage and dog demographic characteristics in Bali, Indonesia. The median number of dogs per subvillage unit (banjar) was 43 (range 0–307) for owned dogs estimated from the DTD survey and 17 (range 0–83) for unconfined dogs (including both owned and unowned) from transects. Vaccination coverage of owned dogs was significantly higher in adults (91.4%) compared to juveniles (<1 year, 43.9%), likely due to insufficient targeting of pups and from puppies born subsequent to vaccination campaigns. Juveniles had a 10–70 times greater risk of not being vaccinated in urban, suburban, and rural areas [combined odds ratios (ORs): 9.9–71.1, 95% CI: 8.6–96.0]. Free-roaming owned dogs were also 2–3 times more likely to be not vaccinated compared to those confined (combined Ors: 1.9–3.6, 95% CI: 1.4–5.4), with more dogs being confined in urban (71.2%) than in suburban (16.1%) and rural areas (8.0%). Vaccination coverage estimates from transects were also much lower (30.9%) than household surveys (83.6%), possibly due to loss of collars used to identify the vaccination status of free-roaming dogs, but these unconfined dogs may also include dogs that were unowned or more difficult to vaccinate. Overall, coverage levels were high in the owned dog population, but for future campaigns in Bali to have the highest chance of eliminating rabies, concerted effort should be made to vaccinate free-roaming dogs particularly in suburban and rural areas, with advertising to ensure that owners vaccinate pups. Long-lasting, cheap, and quick methods are needed to mark vaccinated animals and reassure communities of the reach of vaccination campaigns

    Imbalance of flight-freeze responses and their cellular correlates in the Nlgn3-/y rat model of autism

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    Abstract Background Mutations in the postsynaptic transmembrane protein neuroligin-3 are highly correlative with autism spectrum disorders (ASDs) and intellectual disabilities (IDs). Fear learning is well studied in models of these disorders, however differences in fear response behaviours are often overlooked. We aim to examine fear behaviour and its cellular underpinnings in a rat model of ASD/ID lacking Nlgn3. Methods This study uses a range of behavioural tests to understand differences in fear response behaviour in Nlgn3 −/y rats. Following this, we examined the physiological underpinnings of this in neurons of the periaqueductal grey (PAG), a midbrain area involved in flight-or-freeze responses. We used whole-cell patch-clamp recordings from ex vivo PAG slices, in addition to in vivo local-field potential recordings and electrical stimulation of the PAG in wildtype and Nlgn3 −/y rats. We analysed behavioural data with two- and three-way ANOVAS and electrophysiological data with generalised linear mixed modelling (GLMM). Results We observed that, unlike the wildtype, Nlgn3 −/y rats are more likely to response with flight rather than freezing in threatening situations. Electrophysiological findings were in agreement with these behavioural outcomes. We found in ex vivo slices from Nlgn3 −/y rats that neurons in dorsal PAG (dPAG) showed intrinsic hyperexcitability compared to wildtype. Similarly, stimulating dPAG in vivo revealed that lower magnitudes sufficed to evoke flight behaviour in Nlgn3 −/y than wildtype rats, indicating the functional impact of the increased cellular excitability. Limitations Our findings do not examine what specific cell type in the PAG is likely responsible for these phenotypes. Furthermore, we have focussed on phenotypes in young adult animals, whilst the human condition associated with NLGN3 mutations appears during the first few years of life. Conclusions We describe altered fear responses in Nlgn3 −/y rats and provide evidence that this is the result of a circuit bias that predisposes flight over freeze responses. Additionally, we demonstrate the first link between PAG dysfunction and ASD/ID. This study provides new insight into potential pathophysiologies leading to anxiety disorders and changes to fear responses in individuals with ASD

    Tapping a Foreign Subsidiarys Competence: An Empirical Test of Subsidiaries of Multinational Corporations in South Korea

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    This study examined the conditions under which a foreign subsidiary becomes the competence center within the multinational corporation (MNC)s network. We developed an integrated framework by investigating effects of both subsidiary-level factors and headquarter (HQ)-level factors on subsidiarys competence development. Survey data from 76 foreign subsidiaries of MNCs in South Korea largely supported our hypotheses. We found that subsidiaries with high management autonomy and high network embeddedness in the local market (South Korea) tend to build superior capabilities that would be useful throughout the entire MNC network. Concerning an MNCs management system, our results suggested that technological and managerial knowledge transfer from HQ to subsidiaries plays important roles in helping a subsidiary evolve into a competence center in the MNCs global network

    The theory of the firm and its critics: a stocktaking and assessment

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    Includes bibliographical references."Prepared for Jean-Michel Glachant and Eric Brousseau, eds. New Institutional Economics: A Textbook, Cambridge, Cambridge University Press.""This version: August 22, 2005."Since its emergence in the 1970s the modern economic or Coasian theory of the firm has been discussed and challenged by sociologists, heterodox economists, management scholars, and other critics. This chapter reviews and assesses these critiques, focusing on behavioral issues (bounded rationality and motivation), process (including path dependence and the selection argument), entrepreneurship, and the challenge from knowledge-based theories of the firm

    Effect of Hypothyroidism on Different Forms of Actin in Rat Cerebral Neuronal Cultures Studied by an Improved DNase I Inhibition Assay

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    An improved DNase I inhibition assay for the filamentous actin (F-actin) and monomeric actin (G-actin) in brain cells has been developed. Unlike other methods, the cell lysis conditions and postlysis treatments, established by us, inhibited the temporal inactivation of actin in the cell lysate and maintained a stable F-actin/G-actin ratio for at least 4-5 h after lysis. The new procedure allowed separate quantitation of the noncytoskeletal F-actin in the Tritonsoluble fraction (12,000 g, 10 min supernatant) that did not readily sediment with the Triton-insoluble cytoskeletal Factin (12,000 g, 10 min pellet). We have applied this modified assay system to study the effect of hypothyroidism on different forms of actin using primary cultures of neurons derived from cerebra of neonatal normal and hypothyroid rats. Our results showed a 20% increase in the Triton-insoluble cytoskeletal F-actin in cultures from hypothyroid brain relative to normal controls. In the Triton-soluble fraction, containing the G-actin and the noncytoskeletal F-actin, cultures from hypothyroid brain showed a 15% increase in G-actin, whereas the F-actin remained unaltered. The 10% increase in total actin observed in this fraction from hypothyroid brain could be totally accounted for by the enhancement of G-actin. The mean F-actin/G-actin ratio in this fraction was about 30% higher in the cultures from normal brain compared to that of the hypothyroid system, which indicates that hypothyroidism tends to decrease the proportion of noncytoskeletal F-actin relative to G-actin

    Thyroid hormone-induced morphological differentiation and maturation of astrocytes involves activation of protein kinase A and ERK signalling pathway

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    Thyroid hormone (TH) has a profound effect on astrocyte differentiation and maturation. Astrocytes cultured under TH-deficient conditions fail to transform from flat polygonal morphology to mature, process-bearing, stellate cells. Supplementation of physiological concentrations of TH initiate gradual transformation of the cells and the process takes �48 h to complete. The signal transduction pathways associated with TH-mediated maturation of astrocytes have been investigated. TH treatment caused an initial activation of protein kinase A (PKA), with a peak activity at 2 h which fell back to basal level there after. Although there was no visible change in morphology of the cells during the observed activation of PKA, it was sufficient to drive the process of transformation to completion, suggesting the involvement of downstream regulators of PKA. PKA inhibitors as well as the MEK inhibitor PD098059 attenuated the TH-induced morphological transformation. Further studies showed that TH treatment resulted in a biphasic response on the cellular phospho-MAP kinase (p-MAPK or p-ERK) level: an initial decline in the p-ERK level followed by an induction at 18– 24 h, both of which could be blocked by a PKA inhibitor. Such sustained activation of p-ERK levels by TH at this later stage coincided with initiation of morphological differentiation of the astrocytes and appeared to be critical for the transformation of astrocytes. The nitric oxide synthase (NOS) inhibitor 7-NI inhibited this induction of p-ERK activity. Moreover, the induction was accompanied by a parallel increase in phospho-CREB activity which, however, persisted at the end of the transformation of the astroglial cells

    Thyroid Hormone-Induced Maturation of Astrocytes Is Associated with the Expression of New Variants of Vimentin and Their Phosphorylation

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    The role of thyroid hormone (TH)-induced vimentin expression in promoting the maturation of astrocytes has been investigated. Comparative immunocytochemical staining with vimentin antibody demonstrated distinctly different patterns of expression of vimentin during the progressive maturation of astrocytes of normal and TH-deficient astrocyte cultures. [35S]Methionine labeling of cells showed a significant decline in the level of vimentin in the hypothyroid cultures at all ages from day 5 to 20. Western blot analysis suggested that the maturation of normal astrocytes was associated with the appearance of several acidic and basic variants of vimentin, whose expression was significantly delayed or reduced in the TH-deficient astrocytes. In normal astrocyte cultures, two acidic variants of vimentin, one of similar molecular weight and the other of lower molecular weight, were found to be phosphorylated during the final transformation of the epithelioid form into the mature stellate form. None of these phosphorylated forms was evident in the TH-deficient astrocytes. This was further confirmed by negative immunocytochemical staining of 5- to 18-dayold cultures of TH-deficient astrocytes with antibody TM71, specific to phosphorylated vimentin, compared with age-matched normal astrocytes, which displayed consistent positive staining. The overall results indicate that TH-induced expression of phosphorylated forms of vimentin may be essential for the intracellular organization of the cytoskeleton in a way conducive to the morphological maturation of astrocytes. Key Words: Astrocytes— Morphology—Hypothyroidism—Vimentin— Variants—Phosphorylation

    Role of Thyroid Hormone in the Morphological Differentiation and Maturation of Astrocytes: Temporal Correlation with Synthesis and Organization of Actin

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    Morphological changes and the molecular mechanisms associated with the maturation of astrocytes were studied under normal and thyroid hormone-deficient conditions using long-term (30 days) primary cultures derived from the neonatal rat brain. lmmunocytochemical staining of cells with a monoclonal antibody specific to glial fibrillary acidic protein demonstrated for the first time that, similar to their maturation in vivo, astrocytes maintained in normal serum-containing medium can undergo complete maturation involving two distinct stages of morphological differentiation (from radial glia to flat polygonal cells with epithelioid morphology and then to mature process-bearing cells with stellate morphology). Deficiency of thyroid hormone delays the first step and totally blocks the second stage of differentiation in the maturation process. Comparative staining of normal and thyroid hormone-deficient astrocytes with filamentous actin-specific fluorescein isothiocyanate-phalloidin and quantitation of the various forms of intracellular actin using an improved DNase I assay demonstrated that maturation of astroglial cells is associated with characteristic alterations in the level of cytoskeletal and non- cytoskeletal filamentous (F) actin. In particular, the maintenance of the epithelioid form of the hypothyroid astrocytes is associated with a progressive increase in the level of cytoskeletal F-actin and a concomitant decline in the level of non-cytoskeletal F-actin. Quantitation of actin mRNA by Northern blot analysis and studies on the rate of actin synthesis at various stages of differentiation showed that the initial transformation into the epithelioid form is associated with an increase in the rate of synthesis of actin and the expression of its mRNA, while the final transformation into the mature process-bearing form is correlated with a decline in these parameters. The results indicate that thyroid hormone plays an obligatory role in promoting the differentiation and maturation of astrocytes, and that during this process the hormone regulates the expression of actin and its intracellular organization in a way conducive to morphological differentiation
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