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Evaluation of T Cell Subsets by an Immunocytochemical Method Compared to Flow Cytometry in Four Countries (1997)

LISSE, I. M. ; BÖTTIGER, B. ; CHRISTENSEN, L. B. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Scandinavian journal of immunology 45 (1997), S. 0

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ISSN: 1365-3083

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: The authors tested an alternative method for CD4 and CD8 T lymphocytes enumeration, the immunoalkaline phosphatase method (IA), in three African countries and in Denmark. The IA determinations from 136 HIV antibody positive and 105 HIV antibody negative individuals were compared to the corresponding results obtained by flow cytometry (FC) performed in the respective countries. The authors found good correspondence between the two methods for measurements of CD4 and CD8 T lymphocytes independent of serological status and geographical site. However, the CD4 and CD8 T lymphocyte values obtained by the two methods are not interchangeable as IA compared to FC consistently gives higher percentage of CD4 T lymphocytes, and lower percentages of CD8 T lymphocytes. Mean differences between the two methods did not differ between the three African countries indicating that the IA method provides systematic results. Replicate measurements suggested good correspondence between results obtained by IA. By using an IA level of 〈 300 CD4 T lymphocytes/μl, the sensitivity was 81% and specificity 96% for detecting an FC level of 〈 200 CD4 T lymphocytes/μl. Using an IA level of 〈 20% CD4 T lymphocytes, the sensitivity was 89% and specificity 95% for detecting an FC level of 〈14% CD4 T lymphocytes, The FC and IA methods had the same internal correspondence between low absolute CD4 T cell counts and low CD4 percentages; the sensitivity and specificity for detecting a low absolute CD4 T cell count with a low CD4 percentage was 92% and 68% for FC and 91% and 73% for IA, respectively. The IA method is 10-fold cheaper than FC, is independent of advanced laboratory facilities, and does not need immediate processing of samples as blood smears can be stored for long periods. The IA method is therefore suitable for use in areas with limited resources and laboratory facilities where there is a need for immunological surveillance in hospital or community studies.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3083.1997.d01-440.x

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Turnover of residual 15N-labelled fertilizer N in soil following harvest of oilseed rape (t Brassica napus L.) (1997)

Jensen, L.S. ; Christensen, L. ; Mueller, T. ; [et al.]

Springer

Plant and soil 190 (1997), S. 193-202

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ISSN: 1573-5036

Keywords: extractable organic N ; fertilizer N ; mineral N ; 15N ; N loss ; oilseed rape ; soil microbial biomass N

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract We studied the fate of 15N-labelled fertilizer nitrogen in a sandy loam soil after harvest of winter oilseed rape (Brassica napus L. cv. Ceres) given 100 or 200 kg N ha-1 in spring, with or without irrigation. Our main objective was to quantify the temporal variations of the soil mineral N, the extractable soil organic N and soil microbial biomass N, and fertilizer derived N in these pools during autumn and winter. Nitrogen use efficiency of the oilseed rape crop varied from 47% of applied N in the 100N, irrigated treatment to 34% in the 200N, non-irrigated treatment. However, only in the latter treatment did we find significantly higher fertilizer derived soil mineral N than in the three other treatments which all had low soil mineral N contents at the first sampling after harvest (8 days after stubble tillage). Between 31% and 42% of the applied N could not be accounted for in the harvested plants or 0-15 cm soil layer at this first sampling. Over the following autumn and winter none of the remaining fertilizer derived soil N was lost from the 0–5 cm depth, but from the 5–15 cm depth a marked proportion of N derived from fertilizer was lost, probably by leaching. Negligible amounts of fertilizer derived extractable soil organic and mineral N (〈1 kg N ha-1, 0-15 cm) were found in all treatments after the first sampling. Soil microbial biomass N was not significantly affected by treatments and showed only small temporal variability (±11% of the mean 76 kg N ha-1, 0- 15 cm depth). Surprisingly, the average amount of soil microbial biomass N derived from fertilizer was significantly affected by the treatments, with the extremes being 5.5 and 3.1 kg N ha-1 in the 200N, non-irrigated and 100N, irrigated treatments, respectively. Also, the estimated exponential decay rate of microbial biomass N derived from fertilizer, differed greatly (2 fold) between these two treatments, indicating highly different microbial turnover rates in spite of the similar total microbial biomass N values. In studies utilising 15N labelling to estimate turnover rates of different soil organic matter pools this finding is of great importance, because it may question the assumption that turnover rates are not affected by the insertion of the label.