Monte-Carlo simulation of photon transport in a heterogeneous phantom--I. Application to chest counting of Pu and Am.
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The use of labelled bile salt retention is likely to be a major new technique in assessing the function of the terminal ileum. Papers to date have described two techniques to measure both the 100% and the seven-day retention values. These use whole body counters or uncollimated gamma cameras. We have compared the use of simple probe systems with an uncollimated gamma camera for the retention measurements. There was no significant difference in the results obtained with any of these systems. It is concluded that simple probe measurements can provide a precise and highly reproducible assessment of bile salt retention which greatly increases the availability of this test.
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The dispersion of microbiological counting measurements, when repeating the analysis on the same material both within a laboratory (repeatability) and between laboratories (reproducibility) can be characterized by the organization of interlaboratory studies, where several sets of identical test materials are sent to several laboratories. Using the example of data generated by an interlaboratory study on enumeration of Listeria monocytogenes in foods by the standardized reference method (colony-count technique), 2 types of robust estimators of reproducibility standard deviations, based on the median, were examined, in comparison with the classical estimators, based on the mean. Experimental evaluation indicated that the 3 approaches gave consistent results for most of the combinations. The usual log10 transformation of the enumeration results was also questioned before these calculations were conducted.
Based on immunoassay by particle counting, three methods for antithrombin III, von Willebrand factor and plasminogen were developed on an automated IMPACT machine and on a semi-automated MULTIPACT system. Precision of the techniques, measured at low, medium and high level of the calibration curve showed coefficients of variation varying from 4.3 to 13.8%. Accuracy was evaluated by dilution recovery test and by correlation with rocket immunoelectrophoresis and chromogenic substrate techniques. The results show that the proposed methods correlate well with existing techniques and that immunoassay by particle counting is applicable to several coagulation tests.
Strategic application of moxidectin pour-on (Cydectin) was evaluated in Uganda for its effect on pasture larval counts and gastrointestinal nematode faecal egg counts in village cattle kept under tethering (semi-intensive) grazing management. The strategic deworming schedule involved treating cattle twice at an interval of 2 months, at the end of the 1st wet season and during the 2nd wet season. Two groups of 30 cattle, each consisting of a treated and a control group, were examined for nematode infections every 4 weeks from June 1999 to January 2000. The treated group had significantly lower mean faecal egg counts than the untreated groups (t-value = 2.47, P < 0.05). Generally, the pasture larval counts on treated farms were lower than on untreated ones, but not significantly so (t-value = 2.22, P = 0.068). Pasture larval counts with different nematode species on treated farms were lower than on untreated ones, but the differences were not significant for Haemonchus spp. (t-value = 1.68, P = 0.145), Oesophagostomum spp. (t-value = 1.87, P = 0.111), Trichostrongylus spp. (t-value = 1.93, P = 0.102), Dictyocaulus spp. (t-value = -0.74, P = 0.485) and Cooperia spp. (t-value = -1.00, P = 0.356). Treated farms did, however, have significantly lower pasture larval counts of Bunostomum spp. (t-value = 4.64, P < 0.05). This study has revealed that the application of moxidectin pour-on on cattle has an effect on faecal egg count and pasture contamination under the tethering grazing system. Moxidectin pour-on and the strategic deworming schedule evaluated here could be used for the control of gastrointestinal nematode infections in cattle by small-scale farmers who practise tethering or semi-intensive grazing management in Uganda and other tropical countries, especially where there is a bimodal rainfall pattern.
The complete blood count and leukocyte differential count have no value in screening asymptomatic members of the general population. The complete blood count may be useful for screening infants in the first year of life, institutionalized elderly persons, pregnant women, and recent immigrants from Third World countries, if poor nutrition or inadequate iron intake is suspected. These tests are not useful for hospitalized patients, unless an abnormality is suspected or surgery with major blood loss is anticipated. It is appropriate to obtain the tests when a hematologic or infectious disorder is suspected, but they may not affect decision making if the diagnosis is clinically evident. The leukocyte differential count is unnecessary to confirm an infection in most cases in which leukocytosis is present. Repeat tests should be limited to situations where the clinical course is unclear, and at intervals long enough such that the results might affect clinical decision making.
Platelet counts and platelet size were determined in midtrimester fetuses to obtain reference values to be used in prenatal diagnosis of inheritable platelet disorders. In 17- to 21-week fetuses, platelet counts ranged between 135 and 283 x 10(9)/L, and thus did not differ from those of newborn infants and adults. Mean platelet volume fell between 6.0 and 7.0 fl, which is in the range for adults. The data were used to exclude Wiskott-Aldrich syndrome in an 18-week fetus at 50% risk of being affected.
We evaluate the morphometric point counting method (PCM) for qualitatively analyzing pulmonary inflammation and collagen deposits (i.e., fibrosis) in the assessment of the biological hazards of inhaled respirable particles at a realistic dose comparable to that of exposure in the work environment. Rats were exposed by intratracheal instillation to a 2-mg dose, which is close to the estimated overdose at which macrophage clearance is impared, of each of 3 kinds of particulate matter: crystalline silica, crocidolite asbestos, and titanium dioxide. The lung tissue was evaluated at 3 days, 1 wk, and 1, 3, and 6 mo after exposure. Digital images taken of the lung tissue after processing and staining of the lung sections were examined by the PCM under light microscopy. Evidence of inflammation along with progressive inflammatory changes occurred with crystalline silica and crocidolite, which are well-known hazardous particle types. In contrast, lung tissue from rats exposed to titanium dioxide particles demonstrated a decreasing pattern of histopathological change with increasing retention time. Differences in repair patterns of TiO(2) versus crocidolite and silica following the 2-mg dose exposure suggest that the PCM scoring system may be a useful and sensitive tool for qualitatively evaluating the biological hazards of new particle types, for which no toxicological information exists for low-dose exposure, by using the results from assessment of fibrogenic particle types (such as crocidolite and crystalline silica) as well as particle types with low toxicity (such as TiO(2)) as reference points.
This paper presents a Bayesian analysis of a time series of counts to assess its dependence on an explanatory variable. The time series represented is the incidence of the infectious disease ESBL-producing Klebsiella pneumoniae in an Australian hospital and the explanatory variable is the number of grams of antibiotic (third generation) cephalosporin used during that time. We demonstrate that there is a statistically significant relationship between disease occurrence and use of the antibiotic, lagged by three months. The model used is a parameter-driven model in the form of a generalized linear mixed model. Comparison of models is made in terms of mean square error.
Each column of amino acids in a multiple alignment of protein sequences can be represented as a vector of 20 amino acid counts. For alignment and searching applications, the count vector is an imperfect representation of a position, because the observed sequences are an incomplete sample of the full set of related sequences. One general solution to this problem is to model unobserved sequences by adding artificial 'pseudo-counts' to the observed counts. We introduce a simple method for computing pseudo-counts that combines the diversity observed in each alignment position with amino acid substitution probabilities. In extensive empirical tests, this position-based method out-performed other pseudo-count methods and was a substantial improvement over the traditional average score method used for constructing profiles.