1,721,025 research outputs found
How differential somatic cell counting can help in sustainable herd management.
No full textBovine mastitis is a major cause of economical losses in dairy production. Identification of
infected animals is often difficult, for the etiopathological aspects of the disease, and for the costs of
cyto-bacteriological exams. In the present study we explored the possibility of identifying diseased
animals using only cytological tests.
Milk was sampled from 184 quarters of 50 cows, in 3 herds, and submitted to somatic cell
counting and bacteriological analysis, according to NMC guidelines. Each sample was also
centrifuged, the cell pellet was spread on a slide, stained with May-Grünwald Giemsa, and
evaluated by light microscopy. Relative percentages of leukocytes and three ratios were calculated:
lymphocytes (L%), macrophages (M%), neutrophils (PMN%), and phagocytes per lymphocytes
(Ph/L), macrophages per neutrophils (M/PMN) and neutrophils per lymphocytes (PMN/L). The
ratios were normalized to natural logarithm. Receiver operating characteristic (ROC) curves were
generated for each percentage and ratio. Statistical analysis was performed using Student’s-t test.
Quarters were classified as healthy or diseased based on SCC and bacteriological results. Herd
B and C showed a low and high prevalence of Staphylococcus aureus infected quarters,
respectively, while herd A was free from contagious pathogens.
Differences between groups were significant (P<0.05) for all variables, except for M%.
Natural logarithm (PMN/L) and L% gave the best area under curve values (0.813 and 0.795,
respectively). The overall sensitivity was 82.7% (69.2%, 87.5% and 96.8% in herd A, B and C,
respectively), and the specificity was 63.9%. Based on the different etiologic agents in herd A, a
new ROC analysis for herds free of contagious pathogens was run for both Ln (PMN/L) and L%,
thereby achieving a sensitivity of 79.4%. In conclusion, differential cell count could be used as a
good screening method, reducing the number of bacteriological tests needed, and increasing the
income for farmers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Duplex real-time PCR assay for rapid identification of Staphylococcus aureus isolates from dairy cow milk
No full textStaphylococcus aureus isolates from dairy cow mastitis are not always consistent with the characteristic morphology described, and molecular investigation is often needed. The aim of the study was to develop a duplex real-time PCR assay for rapid identification of S. aureus isolates, targeting both nuc and Sa442. Overall, 140 isolates collected from dairy cow mastitis in 90 different herds, were tested. All strains had been identified using morphological and biochemical characteristics. DNA from each strain was amplified in real-time PCR assay, to detect nuc or Sa442. Thereafter, a duplex real-time PCR assay was performed, and specificity of the amplified products was assessed by high resolution melting curve analysis. Out of 124 S. aureus isolates, 33 did not show the typical morphology or enzymatic activity; in 118 strains, the two melt-curve peaks consistent with nuc and Sa442 were revealed, while 2 isolates showed only the peak consistent with Sa442. Four isolates bacteriologically identified as S. aureus, were PCR-negative and were further identified as S. pseudintermedius by sequencing. Staphylococcus pseudintermedius and coagulase-negative staphylococci did not carry nuc or Sa442. The results showed the correct identification of all isolates, comprehending also coagulase- or nuc-negative S. aureus, while other coagulase-positive Staphylococci were correctly identified as non-S. aureus. Both sensitivity and specificity were 100%. High resolution melting analysis allowed easy detection of unspecific products. Finally, the duplex real-time PCR was applied directly to 40 milk samples, to detect infected mammary quarters. The assay confirmed the results of bacteriological analysis, on S. aureus-positive or -negative samples. Therefore, the proposed duplex real-time PCR could be used in laboratory routine as a cost-effective and powerful tool for high-throughput identification of atypical S. aureus isolates causing dairy cow mastitis. Also, it could be applied directly to milk samples, to detect S. aureus mammary infections avoiding bacteriological analysis
Valutazione della conta differenziale delle cellule del latte in relazione allo stato sanitario della mammella
No full textIn dairy herd management, somatic cell counting is largely used as an indicator of mastitis. Differential cell counts been indicated as a more accurate method for mastitis identification. Little is known, though, about the expected profile in healthy milk samples. This cross-sectional study explored the inflammatory profiles in milk from 2 dairy herds known to be affected by mammary gland infections from different Staphylococcus aureus strains, and 1 herd known to be free of contagious milk pathogens. Milk sampling was performed on 50 animals. Somatic cell counts and bacteriological examination were performed as described on NMC guidelines. Relative percents of lymphocytes (L), macrophages (M), polymorphonuclear cells (PMN); and their ratios were assessed through milk cytology. Results confirmed that herd A was free from contagious pathogens, herd B was positive for a coagulase negative strain of S. aureus, and herd C was positive for S. aureus. In all herds, healthy quarters as well as subclinically mastitic quarters were found. When cytology results were grouped by herd, the inflammatory profiles resulted markedly different. Our results suggest that milk immune response can vary from herd to herd. We do not know, though, if the differences are given to different genetic background, or from different stimulus from the different pathogen strains. Further studies must be done to determinate if a sole factor could be implicated, or if this differences are given to a combination of those factors
Evaluation of biofilm formation using milk in a flow cell model and microarray characterization of Staphylococcus aureus strains from bovine mastitis
No full textIt was hypothesized that biofilm could play an important role in the establishment of chronic . Staphylococcus aureus bovine mastitis. The . in vitro evaluation of biofilm formation can be performed either in closed/static or in flow-based systems. Efforts have been made to characterize the biofilm-forming ability of . S. aureus mastitis isolates, however most authors used static systems and matrices other than UHT milk. It is not clear whether such results could be extrapolated to the mammary gland environment. Therefore, the present study aimed to investigate the biofilm-forming ability of . S. aureus strains from subclinical bovine mastitis using the static method and a flow-based one. One hundred and twelve strains were tested by the classic tissue culture plate assay (TCP) and 30 out of them were also tested by a dynamic semi-quantitative assay using commercial UHT milk as culture medium (Milk Flow Culture, MFC) or Tryptic Soy Broth as control medium (TS Flow Culture, TSFC). Only 6 (20%) strains formed biofilm in milk under flow conditions, while 36.6% were considered biofilm-producers in TCP, and 93.3% produced biofilm in TSFC. No agreement was found between TCP, MFC and TSFC results. The association between strain genetic profile, determined by microarray, and biofilm-forming ability in milk was evaluated. Biofilm formation in MFC was significantly associated with the presence of those genes commonly found in bovine-associated strains, assigned to clonal complexes typically detected in mastitis. Based on our results, biofilm-forming potential of bovine strains should be critically analysed and tested applying conditions similar to mammary environment
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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