404 research outputs found

    Natural parasitism of the Citrus Leafminer (Lepidoptera: Gracillariidae) over eight years in seven citrus regions of SĆ£o Paulo, Brazil

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    The citrus leafminer (CLM) Phyllocnists citrella Stainton (Lepidoptera: Gracillariidae) was frst recorded in Brazil in 1996. In 1998, the parasitoid Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtdae) was introduced and established in many regions of the country. In this study, 130 onehour-samplings of sweet orange leaves (Citrus sinensis [L.] Osbeck) hostng CLM pupal chambers were carried out to estmate the CLM parasitsm rate (%) by its parasitoids in 7 regions of SĆ£o Paulo State between 2000 and 2008. The sample sizes varied from 10 to 275 leaves (mean = 65). The most abundant parasitoid was the encyrtd A. citricola (found in 91.8% of the samplings). The highest level of CLM parasitsm by A. citricola was recorded in the southern region (Botucatu), 70.2 Ā± 6.6 (mean Ā± SEM), and the lowest level was recorded in the northern region (Barretos), 12.8 Ā± 5.7%. CLM parasitsm by A. citricola and by natve parasitoids (Galeopsomyia fausta LaSalle, Cirrospilus spp. and Elasmus sp.) did not diļ¬€er between seasons. The 6-fold increase in the use of insectcides in citrus groves, afer 2004 when the Huanglongbing (HLB) disease was found in SĆ£o Paulo State, did not reduce the level of CLM parasitsm. The level of parasitsm was 50.8 Ā± 4.2% before the advent of HLB (2000ā€“2004) and 56.0 Ā± 4.4% thereafer (2005ā€“2008), indicatng adaptaton of A. citricola in a disturbed agroecosystem.A minadora das folhas dos citros (MFC), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), foi encontrada pela primeira vez no Brasil em 1996. Em 1998, o parasitoide Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtidae) foi introduzido e se estabeleceu em vĆ”rias regiƵes do paĆ­s. Nesse estudo, foram feitas130 amostragens, de uma hora, de folhas de laranjeiras doces [Citrus sinensis (L.) Osbeck] com cĆ¢maras pupais da MFC, para se estimar o parasitismo da MFC em 7 regiƵes do estado de SĆ£o Paulo, entre 2000 e 2008. O tamanho das amostras variou de 10 a 275 folhas (mĆ©dia = 65). O parasitoide mais abundante foi o encirtĆ­deo A. citricola (encontrado em 91.8% das amostragens). O maior parasitismo da MFC por A. citricola foi observado na regiĆ£o sul do estado (Botucatu), 70,2 Ā± 6,6 (mĆ©dia Ā± EPM), e o menor parasitismo na regiĆ£o norte (Barretos), 12,8 Ā± 5,7%. O parasitismo da MFC por A. citricola e seus parasitoides nativos (Galeopsomyia fausta LaSalle, Cirrospilus spp. and Elasmus sp.) nĆ£o diferiram entre as estaƧƵes do ano. O aumento de seis vezes no uso de inseticidas nos pomares de citros, apĆ³s 2004, quando o Huanglongbing (HLB) foi encontrado no estado de SĆ£o Paulo, nĆ£o reduziu o nĆ­vel de parasitismo da MFC. O nĆ­vel mĆ©dio de parasitismo foi de 50,8 Ā± 4,2%, antes do HLB (2000-2004), e 56,0 Ā± 4,4%, apĆ³s o HLB (2005-2008), indicando a adaptaĆ§Ć£o de A. citricola a um agroecossistema perturbado.info:eu-repo/semantics/publishedVersio

    Measuring portfolio performance using a modified measure of risk

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    This paper reports the results of an investigation into the properties of a theoretical modification of beta proposed by Leland (1999) and based on earlier work of Rubinstein (1976). It is shown that when returns are elliptically symmetric, beta is the appropriate measure of risk and that there are other situations in which the modified beta will be similar to the traditional measure based on the capital asset pricing model. For the case where returns have a normal distribution, it is shown that the criterion either does not exist or reduces exactly to the conventional beta. It is therefore conjectured that the modified measure will only be useful for portfolios that have nonstandard return distributions which incorporate skewness. For such situations, it is shown how to estimate the measure using regression and how to compare the resulting statistic with a traditional estimated beta using Hotelling's test. An empirical study based on stocks from the FTSE350 does not find evidence to support the use of the new measure even in the presence of skewness.Journal of Asset Management (2007) 7, 388-403. doi:10.1057/palgrave.jam.225005

    Primary cilia elongation in response to interleukin-1 mediates the inflammatory response

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    Primary cilia are singular, cytoskeletal organelles present in the majority of mammalian cell types where they function as coordinating centres for mechanotransduction, Wnt and hedgehog signalling. The length of the primary cilium is proposed to modulate cilia function, governed in part by the activity of intraflagellar transport (IFT). In articular cartilage, primary cilia length is increased and hedgehog signaling activated in osteoarthritis (OA). Here, we examine primary cilia length with exposure to the quintessential inflammatory cytokine interleukin-1 (IL-1), which is up-regulated in OA. We then test the hypothesis that the cilium is involved in mediating the downstream inflammatory response. Primary chondrocytes treated with IL-1 exhibited a 50Ā % increase in cilia length after 3Ā h exposure. IL-1-induced cilia elongation was also observed in human fibroblasts. In chondrocytes, this elongation occurred via a protein kinase A (PKA)-dependent mechanism. G-protein coupled adenylate cyclase also regulated the length of chondrocyte primary cilia but not downstream of IL-1. Chondrocytes treated with IL-1 exhibit a characteristic increase in the release of the inflammatory chemokines, nitric oxide and prostaglandin E2. However, in cells with a mutation in IFT88 whereby the cilia structure is lost, this response to IL-1 was significantly attenuated and, in the case of nitric oxide, completely abolished. Inhibition of IL-1-induced cilia elongation by PKA inhibition also attenuated the chemokine response. These results suggest that cilia assembly regulates the response to inflammatory cytokines. Therefore, the cilia proteome may provide a novel therapeutic target for the treatment of inflammatory pathologies, including OA

    The taxanes: toxicity and quality of life considerations in advanced ovarian cancer

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    The taxanes paclitaxel and docetaxel show good activity in the management of advanced ovarian cancer when used in conjunction with platinum agents. Accumulating evidence from clinical studies, particularly the latest results from the phase III comparative SCOTROC study, indicates that the two drugs confer similar rates of tumour response and survival in women with this condition. However, it is clear that paclitaxel and docetaxel differ in their tolerability profiles and in other respects, and cannot be regarded as directly equivalent drugs. In particular, paclitaxel is associated with significant neurotoxicity; peripheral neuropathy has also been reported with docetaxel, but to a lesser extent. Neutropenia appears more prevalent with docetaxel than with paclitaxel, although clinical trial data show that this adverse effect is manageable and need not compromise dose delivery. Docetaxel is also associated with potential benefits accruing from shorter infusion times and lack of need for premedication with intravenous histamine H1 and H2 antagonists. Emerging quality of life data are expected to shed further light on the overall benefit of chemotherapy in women with advanced ovarian cancer in general, and on taxaneāˆ’platinum combinations in particular

    The evolution of rotating stars

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    First, we review the main physical effects to be considered in the building of evolutionary models of rotating stars on the Upper Main-Sequence (MS). The internal rotation law evolves as a result of contraction and expansion, meridional circulation, diffusion processes and mass loss. In turn, differential rotation and mixing exert a feedback on circulation and diffusion, so that a consistent treatment is necessary. We review recent results on the evolution of internal rotation and the surface rotational velocities for stars on the Upper MS, for red giants, supergiants and W-R stars. A fast rotation is enhancing the mass loss by stellar winds and reciprocally high mass loss is removing a lot of angular momentum. The problem of the ``break-up'' or Ī©\Omega-limit is critically examined in connection with the origin of Be and LBV stars. The effects of rotation on the tracks in the HR diagram, the lifetimes, the isochrones, the blue to red supergiant ratios, the formation of W-R stars, the chemical abundances in massive stars as well as in red giants and AGB stars, are reviewed in relation to recent observations for stars in the Galaxy and Magellanic Clouds. The effects of rotation on the final stages and on the chemical yields are examined, as well as the constraints placed by the periods of pulsars. On the whole, this review points out that stellar evolution is not only a function of mass M and metallicity Z, but of angular velocity Ī©\Omega as well.Comment: 78 pages, 7 figures, review for Annual Review of Astronomy and Astrophysics, vol. 38 (2000

    Specific fatty acid intake and the risk of pancreatic cancer in Canada

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    The possible association of specific fatty acid (FA) intake and pancreatic cancer risk was investigated in a population-based caseā€“control study of 462 histologically confirmed cases and 4721 frequency-matched controls in eight Canadian provinces between 1994 and 1997. Dietary intake was assessed by means of a self-administered food frequency questionnaire. Unconditional logistic regression was used to assess associations between dietary FAs and pancreatic cancer risk. After adjustment for age, province, body mass index, smoking, educational attainment, fat and total energy intake, statistically significant inverse associations were observed between pancreatic cancer risk and palmitate (odds ratios (ORs)=0.73; 95% confidence intervals (CIs) 0.56ā€“0.96; P-trend=0.02), stearate (OR=0.70; 95% CI 0.51ā€“0.94; P-trend=0.04), oleate (OR=0.75; 95% CI 0.55ā€“1.02; P-trend=0.04), saturated FAs (OR=0.67; 95% CI 0.50ā€“0.91; P-trend=0.01), and monounsaturated FAs (OR=0.72; 95% CI 0.53ā€“0.98; P-trend=0.02), when comparing the highest quartile of intake to the lowest. Significant interactions were detected between body mass index and both saturated and monounsaturated FAs, with a markedly reduced risk associated with intake of stearate (OR=0.36; 95% CI 0.18ā€“0.70; P-trend=0.001), oleate (OR=0.36; 95% CI 0.19ā€“0.72; P-trend=0.002), saturated FAs (OR=0.35; 95% CI 0.18ā€“0.67; P-trend=0.002), and monounsaturated FAs (OR=0.32; 95% CI 0.16ā€“0.63; P-trend<0.0001) among subjects who are obese. The results suggest that substituting polyunsaturated FAs with saturated or monounsaturated FAs may reduce pancreatic cancer risk, independently of total energy intake, particularly among obese subjects

    Relation of mitral valve morphology and motion to mitral regurgitation severity in patients with mitral valve prolapse

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    <p>Abstract</p> <p>Background</p> <p>Mitral valve thickness is used as a criterion to distinguish the classical from the non-classical form of mitral valve prolapse (MVP). Classical form of MVP has been associated with higher risk of mitral regurgitation (MR) and concomitant complications. We sought to determine the relation of mitral valve morphology and motion to mitral regurgitation severity in patients with MVP.</p> <p>Methods</p> <p>We prospectively analyzed transthoracic echocardiograms of 38 consecutive patients with MVP and various degrees of MR. In the parasternal long-axis view, leaflets length, diastolic leaflet thickness, prolapsing depth, billowing area and non-coaptation distance between both leaflets were measured.</p> <p>Results</p> <p>Twenty patients (53%) and 18 patients (47%) were identified as having moderate to severe and mild MR respectively (ERO = 45 Ā± 27 mm<sup>2 </sup>vs. 5 Ā± 7 mm<sup>2</sup>, p < 0.001). Diastolic leaflet thickness was similar in both groups (5.5 Ā± 0.9 mm vs. 5.3 Ā± 1 mm, p = 0.57). On multivariate analysis, the non-coaptation distance (OR 7.9 per 1 mm increase; 95% CI 1.72-37.2) was associated with significant MR. Thick mitral valve leaflet as traditionally reported (ā‰„ 5 mm) was not associated with significant MR (OR 0.9; 95% CI 0.2-3.4).</p> <p>Conclusions</p> <p>In patients with MVP, thick mitral leaflet is not associated with significant MR. Leaflet thickness is probably not as important in risk stratification as previously reported in patients with MVP. Other anatomical and geometrical features of the mitral valve apparatus area appear to be much more closely related to MR severity.</p

    Sweets, sweetened beverages, and risk of pancreatic cancer in a large population-based caseā€“control study

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    We examined the associations between sweets, sweetened and unsweetened beverages, and sugars and pancreatic cancer risk. We conducted a population-based caseā€“control study (532 cases, 1,701 controls) and used multivariate logistic regression models to calculate odds ratios (OR) and 95% confidence intervals (CI). Because associations were often different by sex, we present results for men and women combined and separately. Among men, greater intakes of total and specific sweets were associated with pancreatic cancer risk (total sweets: ORĀ =Ā 1.9, 95% CI: 1.0, 3.6; sweet condiments: ORĀ =Ā 1.9, 95% CI: 1.2, 3.1; chocolate candy: ORĀ =Ā 2.4, 95% CI: 1.1, 5.0; other mixed candy bars: ORĀ =Ā 3.3, 95% CI: 1.5, 7.3 for 1Ā +Ā servings/day versus none/rarely). Sweets were not consistently associated with risk among women. Sweetened beverages were not associated with increased pancreatic cancer risk. In contrast, low-calorie soft drinks were associated with increased risk among men only; while other low-/non-caloric beverages (e.g., coffee, tea, and water) were unassociated with risk. Of the three sugars assessed (lactose, fructose, and sucrose), only the milk sugar lactose was associated with pancreatic cancer risk (ORĀ =Ā 2.0, 95% CI: 1.5, 2.7 comparing extreme quartiles). These results provide limited support for the hypothesis that sweets or sugars increase pancreatic cancer risk

    Reproductive and hormonal factors and mortality among women with colorectal cancer in the NIH-AARP Diet and Health Study

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    BACKGROUND: Although use of menopausal hormone therapy (MHT) and some reproductive factors have been associated with colorectal cancer (CRC) risk, relations between these factors and survival after CRC diagnosis are unclear. METHODS: Among 2053 post-menopausal women diagnosed with incident CRC in the NIH-AARP Diet and Health Study, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) using multivariable Cox proportional hazards regression to test associations between oral contraceptive (OC) use, menarche age, age at first birth, parity, menopausal age, and MHT use with all-cause and CRC-specific mortality. RESULTS: There were 759 deaths (332 CRC-related deaths) over a median follow-up of 7.7 years. We observed no statistically significant associations between OC use, menarche age, age at first birth, parity, menopausal age, and mortality. Compared with never MHT use, former use was not associated with mortality, but we found an inverse association among baseline current users, for both all-cause (HR=0.79, 95% CI 0.66ā€“0.94) and CRC mortality (0.76, 0.59ā€“0.99). CONCLUSION: Future studies should further focus on the mechanisms by which exogenous oestrogen exposure might affect tumour progression and CRC survival
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