915 resultados para Sources of resistance
Resumo:
Haemonchus contortus is one of the most common and economically significant causes of disease in small ruminants worldwide, and the control programs of parasitic nematodes - including H. contortus - rely mostly on the use of anthelmintic drugs. The consequence of the use of this, as the sole sanitary strategy to avoid parasite infections, was the reduction of the efficacy of all chemotherapeutic products with a heavy selection for resistance. The widespread of anthelmintic resistance and the difficulty of its early diagnosis has been a major concern for the sustainable parasite management on farms. The objective of this research was to determine and compare the ivermectin (IVM) and moxidectin (MOX) effect in a selected field strain of H. contortus with a known resistance status, using the in vitro larval migration on agar test (LMAT). Third stage larvae of the selected isolate were obtained from faecal cultures of experimentally infected sheep and incubated in eleven increasing diluted concentrations of IVM and MOX (6, 12, 24, 48, 96, 192, 384, 768, 1536, 3072 and 6144µg/mL). The dose-response sigmoidal curves were obtained using the R² value of >0.90 and the lethal concentration (LC50) dose for the tested anthelmintic drugs using a four-parameter logistic model. The LC50 value for MOX was significantly lower than IVM (1.253µg/mL and 91.06µg/mL), identifying the H. contortus isolate as considerably less susceptible to IVM compared to MOX. Furthermore, the LMAT showed a high consistency (p<0.0001) and provided to be a useful diagnostic tool for monitoring the resistance status of IVM and MOX in H. contortus field isolate, as well as it may be used for official routine drug monitoring programs under the Ministry of Agriculture (MAPA) guidance.
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New challenges have been created in the modern work environment as the diversity of the workforce is greater than ever in terms of generations. There will become a large demand of generation Y employees as the baby boomer generation employees retire at an accelerated rate. The purpose of this study is to investigate Y generation specific characteristics and to identify motivational systems to enhance performance. The research questions are: 1. What are Y generation characteristics? 2. What motivational systems organizations can form to motivate Y generation employees and in turn, create better performance? The Y generation specific characteristics identified from the literature include; achievement oriented; confident; educated; multitasking; having a need for feedback; needing management support; sociable and tech savvy. The proposed motivational systems can be found in four areas of the organization; HRM, training and development, communication and decision making policies. Three focus groups were held to investigate what would motivate generation Y employees to achieve better performance. Two of these focus groups were Finnish natives and the third consisted of international students. The HRM systems included flexibility and a culture of fun. It was concluded that flexibility within the workplace and role was a great source of motivation. Culture of fun was not responded to as favorably although most focus group participants rated enjoyableness as one of their top motivating factors. Training and development systems include training programs and mentoring as sources of potential motivation. Training programs were viewed as a mode to gain a better position and were not necessarily seen as motivational systems. Mentoring programs were not concluded to have a significant effect on motivation. Communication systems included keeping up with technology, clarity and goals as well as feedback. Keeping up with technology was seen as an ineffective tool to motivate. Clarity and goal setting was seen as very important to be able to perform but not necessarily motivating. Feedback had a highly motivating effect on these focus groups. Decision making policies included collaboration and teamwork as well as ownership. Teams were familiar and meet the social needs of Y generation employees and are motivating. Ownership was equated with trust and responsibility and was highly valued as well as motivating to these focus group participants.
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The resistance of barnyardgrass (Echinochloa crus-galli) to imidazolinone herbicides is a worldwide problem in paddy fields. A rapid diagnosis is required for the selection of adequate prevention and control practices. The objectives of this study were to develop expedite bioassays to identify the resistance to imidazolinone herbicides in barnyardgrass and to evaluate the efficacy of alternative herbicides for the post-emergence control of resistant biotypes. Three experiments were conducted to develop methods for diagnosis of resistance to imazethapyr and imazapyr + imazapic in barnyardgrass at the seed, seedling and tiller stages, and to carry out a pot experiment to determine the efficacy of six herbicides applied at post-emergence in 13 biotypes of barnyardgrass resistant to imidazolinones. The seed soaking bioassay was not able to differentiate the resistant and susceptible biotypes. The resistance of barnyardgrass to imidazolinones was effectively discriminated in the seedlings and tiller bioassays seven days after incubation at the concentrations of 0.001 and 0.0001 mM, respectively, for both imazethapyr and imazapyr + imazapic. The biotypes identified as resistant to imidazolinones showed different patterns of susceptibility to penoxsulam, bispyribac-sodium and pyrazosulfuron-ethyl, and were all controlled with profoxydim and cyhalofop-butyl. The seedling and tiller bioassays are effective in the diagnosis of barnyardgrass resistance to imidazolinone herbicides, providing an on-season opportunity to identify the need to use alternative herbicides to be applied at post-emergence for the control of the resistant biotypes.
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Parasitic weed species of the genus Orobanche are serious threat for the production of several crops in Europe, Africa and Asia. Research on resistant host plant varieties is one of the most effective management strategies for this parasitic weed. In this study, the susceptibility of twenty-nine tomato varieties to broomrape infection (Orobanche aegyptiaca) under greenhouse conditions was investigated. The employed experimental design was completely randomized with three replications. Differences in susceptibility to infection were monitored among tomato varieties based on their difference in the number of emerged shoots of broomrape and broomrape dry weight (shoots and tubercles). Date of Orobanche emergence varied over a period of 3 to 30 days between varieties. Very late infection was monitored for varieties of Cal-jN3, Viva, Caligen 86, Packmor, CSX 5013, Hyb. PS 6515 and Hyb Petopride5. Differences in the growth and fruit yield among tomato varieties were also found in response to broomrape infestation. Moderate levels of resistance were obtained in Viva, Caligen 86, Hyb. PS 6515, Hyb.Firenze (PS 8094) and Cal-jN3 among other tomato varieties. In contrast, varieties of Kimia-Falat, Hyb. Petopride II and Hyb.AP865 were the most susceptible hosts to Orobanche aegyptiaca.
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Six wheat genotypes and their F1 and F2 generations were exposed to the action of Helminthosporium sativum culture filtrates to examine the genetics of hexaploid wheat resistance. The objective was to improve the efficiency of breeding programs by identifying the action and number of genes involved in the resistance. The varied response of the tested genotypes to the culture filtrates allowed division of the genotypes into four groups: resistant, moderately resistant, moderately susceptible and susceptible. This variability was detected in the progeny, suggesting that the parents have distinct genetic constitutions. Additive gene action predominated and genetic gain was shown to be possible through selection. The genetic control of the resistance trait seems to be complex because of the presence of gene interaction and the difficulty of eliminating the environmental effects. The inheritance seems to be oligogenic
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The role of different cytokines in the peripheral blood mononuclear cell (PBMC) proliferative response and in in vitro granuloma formation was evaluated in a cross-sectional study with patients with the different clinical forms and phases of Schistosoma mansoni infection, as well as a group of individuals "naturally" resistant to infection named normal endemic (NE). The blockage of IL-4 and IL-5 using anti-IL-4 and anti-IL-5 antibodies significantly reduced the PBMC proliferative response to soluble egg (SEA) and adult worm (SWAP) antigens in acute (ACT), chronic intestinal (INT) and hepatosplenic (HS) patients. Similar results were obtained in the in vitro granuloma formation. Blockage of IL-10 had no significant effect on either assay using PBMC from ACT or HS. In contrast, the addition of anti-IL-10 antibodies to PBMC cultures from INT patients significantly increased the proliferative response to SEA and SWAP as well as the in vitro granuloma formation. Interestingly, association of anti-IL-4 and anti-IL-10 antibodies did not increase the PBMC proliferative response of these patients, suggesting that IL-10 may act by modulating IL-4 and IL-5 secretion. Addition of recombinant IL-10 decreased the proliferative response to undetectable levels when PBMC from patients with the different clinical forms were used. Analysis of IFN-g in the supernatants showed that PBMC from INT patients secreted low levels of IFN-g upon antigenic stimulation. In contrast, PBMC from NE secreted high levels of IFN-g. These data suggest that IL-10 is an important cytokine in regulating the immune response and possibly controlling morbidity in human schistosomiasis mansoni, and that the production of IFN-g may be associated with resistance to infection.
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Kartta kuuluu A. E. Nordenskiöldin kokoelmaan
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Shigella spp are Gram-negative, anaerobic facultative, non-motile, and non-sporulated bacilli of the Enterobacteriaceae family responsible for "Shigellosis" or bacillary dysentery, an important cause of worldwide morbidity and mortality. However, despite this, there are very few epidemiological studies about this bacterium in Brazil. We studied the antibiotic resistance profiles and the clonal structure of 60 Shigella strains (30 S. flexneri and 30 S. sonnei) isolated from shigellosis cases in different cities within the metropolitan area of Campinas, State of São Paulo, Brazil. We used the following well-characterized molecular techniques: enterobacterial repetitive intergenic consensus, repetitive extragenic palindromic, and double-repetitive element-polymerase chain reaction to characterize the bacteria. Also, the antibiotic resistance of the strains was determined by the diffusion disk method. Many strains of S. flexneri and S. sonnei were found to be multi-resistant. S. flexneri strains were resistant to ampicillin in 83.3% of cases, chloramphenicol in 70.0%, streptomycin in 86.7%, sulfamethoxazole in 80.0%, and tetracycline in 80.0%, while a smaller number of strains were resistant to cephalothin (3.3%) and sulfazotrim (10.0%). S. sonnei strains were mainly resistant to sulfamethoxazole (100.0%) and tetracycline (96.7%) and, to a lesser extent, to ampicillin (6.7%) and streptomycin (26.7%). Polymerase chain reaction-based typing supported the existence of specific clones responsible for the shigellosis cases in the different cities and there was evidence of transmission between cities. This clonal structure would probably be the result of selection for virulence and resistance phenotypes. These data indicate that the human sanitary conditions of the cities investigated should be improved.
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The objective of the present study was to assess the effects of the immunosuppressant rapamycin (Rapamune®, Sirolimus) on both resistance vessel responsiveness and atherosclerosis in apolipoprotein E-deficient 8-week-old male mice fed a normal rodent diet. Norepinephrine (NE)-induced vasoconstriction, acetylcholine (ACh)- and sodium nitroprusside (SNP)-induced vasorelaxation of isolated mesenteric bed, and atherosclerotic lesions were evaluated. After 12 weeks of orally administered rapamycin (5 mg·kg-1·day-1, N = 9) and compared with untreated (control, N = 9) animals, rapamycin treatment did not modify either NE-induced vasoconstriction (maximal response: 114 ± 4 vs 124 ± 10 mmHg, respectively) or ACh- (maximal response: 51 ± 8 vs 53 ± 5%, respectively) and SNP-induced vasorelaxation (maximal response: 73 ± 6 vs 74 ± 6%, respectively) of the isolated vascular mesenteric bed. Despite increased total cholesterol in treated mice (982 ± 59 vs 722 ± 49 mg/dL, P < 0.01), lipid deposition on the aorta wall vessel was significantly less in rapamycin-treated animals (37 ± 12 vs 68 ± 8 µm² x 10³). These results indicate that orally administered rapamycin is effective in attenuating the progression of atherosclerotic plaque without affecting the responsiveness of resistance vessels, supporting the idea that this immunosuppressant agent might be of potential benefit against atherosclerosis in patients undergoing therapy.
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Abstract The reduction of skeletal muscle loss in pathological states, such as muscle disuse, has considerable effects in terms of rehabilitation and quality of life. Since there is no currently effective and safe treatment available for skeletal muscle atrophy, the search for new alternatives is necessary. Resistance exercise (RE) seems to be an important tool in the treatment of disuse-induced skeletal muscle atrophy by promoting positive functional (strength and power) and structural (hypertrophy and phenotypic changes) adaptive responses. Human and animal studies using different types of resistance exercise (flywheel, vascular occlusion, dynamic, isometric, and eccentric) have obtained results of great importance. However, since RE is a complex phenomenon, lack of strict control of its variables (volume, frequency, intensity, muscle action, rest intervals) limits the interpretation of the impact of the manipulation on skeletal muscle remodeling and function under disuse. The aim of this review is to critically describe the functional and morphological role of resistance exercise in disuse-induced skeletal muscle atrophy with emphasis on the principles of training.
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The aim of this study was to compare the effect of an intermittent intense aerobic exercise session and a resistance exercise session on blood cell counts and oxidative stress parameters in middle-aged women. Thirty-four women were selected and divided into three groups: RE group (performing 60 min of resistance exercises, N = 12), spinning group (performing 60 min of spinning, N = 12), and control group (not exercising regularly, N = 10). In both exercise groups, lymphocytes and monocytes decreased after 1-h recuperation (post-exercise) compared to immediately after exercise (P < 0.05). Immediately after exercise, in both exercised groups, a significant increase in TBARS (from 16.5 ± 2 to 25 ± 2 for the spinning group and from 18.6 ± 1 to 28.2 ± 3 nmol MDA/mL serum for the RE group) and protein carbonyl (from 1.0 ± 0.3 to 1.6 ± 0.2 for the spinning group and from 0.9 ± 0.2 to 1.5 ± 0.2 nmol/mg protein for the RE group) was observed (P < 0.05). A decrease in antioxidant activities (non-protein sulfhydryl, superoxide dismutase, catalase) was also demonstrated with a negative correlation between damage markers and antioxidant body defenses (P < 0.05). These results indicate that an acute bout of intermittent or anaerobic exercise induces immune suppression and increases the production of reactive oxygen species, causing oxidative stress in middle-aged and trained women. Furthermore, we demonstrated that trained women show improved antioxidant capacity and lower oxidative damage than sedentary ones, demonstrating the benefits of chronic regular physical activity.
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Starch derivatives of taro (Colocasia esculenta L. Schott) and rice were characterized as wall materials of orange oil (d-limonene) by spray drying. Native starches were initially hydrolyzed with HCl and then esterified. Succinylated starches were modified using a conventional method in a slurry and were extruded; whereas, the phosphorylated starches were modified using the extrusion process. Viscosity and solubility of starches reduced after acid hydrolysis, derivatization, and extrusion. The particle size of the wall materials ranged between 20.05 and 31.81 µm. The encapsulation efficiency of the phosphorylated taro, rice, and waxy corn starches was 96.9, 96.8 and 97.1% respectively, and 98.6, 98.1, and 98.8% for succynilated taro, rice, and waxy corn starches, respectively. Starch derivatives of taro and rice could potentially be used as wall materials of orange oil d-limonene.
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The intake of carotenoids is associated with antioxidant properties and some of these substances have activity of pro-vitamin A. This study aimed to estimate the intake of carotenoids (average values) by the Brazilian population focusing on beneficiaries of the 'Bolsa Família' Program and identify the dietary sources, according to the purpose and degree of processing and the inclusion of food additives. The database used is the personal food consumption module of the Household Budget Survey of 2008-2009, conducted by the Brazilian Institute of Geography and Statistics. The content of carotenoids in foods was obtained primarily from a National data source. Food products were classified into three categories: 1) fresh and minimally processed foods; 2) processed foods (containing food additives, except for flavoring and coloring agents); and 3) highly processed foods (containing flavoring and coloring agents). Insufficient intakes were identified for the conditional cash transfer program beneficiaries (3,547.1 µg). Fresh and minimally processed foods supplied between 48.6% (for girls) and 65.7% (for male adults) of pro-vitamin carotenoids. Processed foods were sources of between 55.5% and 57.0% of lutein + zeaxanthin for elderly and between 58.0% and 67.8% of lycopene for adults. Highly processed foods contributed to less than 5.0% of total carotenoids.