Automation for clinical CD4 T-cell enumeration, a desirable tool in the hands of skilled operators.

BACKGROUND: Automation in HIV clinical flow cytometry when appropriately applied brings considerable standardisation benefits. The Canadian Immunology Quality Assessment Program (CIQAP) detected situations where operators did not manually override automated software in the event of improper output on the Epics XL and FC500 CD4 immunophenotyping platforms. The automated gating algorithm identifies lymphocytes using a double gate strategy based on CD45 × side scatter (SS) gating and a light scatter FS × SS gate known to fail with sub optimal specimens. METHOD: To generate correct interpretation and results CIQAP introduced a simple protocol modification, bypassing the light scatter gate to include all cells characterized by the CD45 gate. Seventeen problem cases were reanalysed for both absolute and relative T-cell subsets accuracy and compared to the CIQAP group mean values. Results were found to be associated with the percentage of lymphocytes excluded by the automated light scatter gate. RESULTS: The modified manual protocol resolved poor performance in 14 instances out of 17 problem cases. It was found to improve accuracy when the light scatter gate excluded greater than 5% of the cells. The remaining three cases had a lymphocyte recovery of greater than 94.6% in the original automated analysis. CONCLUSION: There is a risk in relying solely on automated gating procedures when using the Epics XL and FC500 CD4 immunophenotyping platforms. Laboratory managers have the responsibility to intervene when required. EQA providers are equally responsible to alert the clinical laboratories of the need to update operator training to deal with stressed specimens. © 2016 International Clinical Cytometry Society.

Ultrastructural morphometric study of follicular center lymphocytes: II. Analyses of cleaved-cell populations do not support the Lukes-Collins' concept.

Ultrastructural morphometric analysis was carried out on six cases of lymph node biopsies with reactive hyperplasia to establish the frequency and depth of invaginations in nuclear profiles situated in the mantle zones and follicular centers. The frequency distribution of the depth of invaginations was similar in nuclear profiles whether in the small lymphocytes of mantle zones or the small, partially transformed (centrocytes) and fully transformed (centroblasts) lymphocytes of follicular centers. Invaginated and cleaved lymphocytes were not confined to the partially transformed (centrocytic) lymphocytes of follicular centers, and nuclear profiles with invaginations bore no resemblance to those depicted in the Lukes-Collins model. A considerable proportion of mantle zone lymphocyte nuclear profiles had invaginations (ranging from 7.5% to 53.6%) and there was no difference between the frequency of deep indentations or clefts in mantle zone lymphocytes (8.1 +/- 5.4%) and the small unstimulated (9.3 +/- 5.3%) and partially transformed (8.4 +/- 1.4%) lymphocytes in follicular centers. Computer modeling of stylized nuclei with conical indentations indicated that all lymphocytic nuclei likely have multiple invaginations or groove-like creases.

Ultrastructural morphometric study of follicular center lymphocytes: I. Nuclear characteristics and the Lukes-Collins' concept.

A combined ultrastructural and morphometric image analysis study was carried out on the nuclear profiles of follicular center and mantle zone lymphocytes of six cases of reactive hyperplasia in human lymph node biopsies. For accuracy of morphological observations and sampling at low magnifications, sections were mounted on formvar-covered slot grids. Measurements of nuclear profile features of small (untransformed) lymphocytes in mantle zones served as the standard for a supposed unimodal population in each case. Analysis of nuclear profile area values indicated that during lymphocyte transformation in follicular centers nuclei had a gradual and progressive increase in size and that the sampled nuclear profiles in both the mantle zone and follicular center were unimodal. Lymphocyte nuclear shape (contour index) was a more complex, and likely biologically independent, feature than nuclear area in both the mantle zone and follicular center. Nuclear profile contour indexes of mantle zone lymphocytes were more irregular than suspected and in some cases had mean values greater than those of follicular center lymphocytes. Furthermore, the frequency distribution of nuclear contour index was not normally distributed in either the follicular center or mantle zone due to the presence of a small proportion of highly irregularly shaped nuclear profiles in both sites. The results indicated that some premises of existing concepts of follicular center cells and the process of lymphocyte transformation in follicular centers were incorrect and should not be directly extrapolated to the nuclear profile characteristics in non-Hodgkin's lymphoma.

An investigation of shear bond strengths of various resin-bonded inner surface rest seat designs for removable partial dentures.

Results and conclusions that can be drawn from this study are: All smooth, mesh, and seating preparation groups produced mean bond strengths significantly greater than that of the control group (p less than 0.01). The cast mesh rest seats exhibited significantly greater bond strengths at 24 hours (p = .0072). However, at 30 days, statistically significant differences between the three groups were not evident. Mean bond strengths for the electrolytically etched rest seat groups increased significantly at 30 days compared with the 24-hour means (p less than .05). These results suggest that an electrolytically etched resin-bonded rest seat can easily withstand the functional stresses exerted by a removable partial denture. The incorporation of seating preparation on an abutment tooth for an etched resin-bonded lingual rest seat seems to offer no advantage in terms of retentive strength.