PubMed · 9348984
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P Carroll. 1997. Lab reports--clarifying the CBC.. https://pubmed.ncbi.nlm.nih.gov/9348984/
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The flow cytometric analysis of reticulated platelets based on the fluorescent derivatization of their RNA content is increasingly used for the diagnostic classification of patients with thrombocytopenia as well as the monitoring of thrombopoiesis recovering under therapy. Many different modifications of the analytical protocol have been published following the first description in 1990 but consensus on the method has not yet been established. We have now reevaluated the assay's methodology in order to optimize sensitivity and specificity and reduce the time length of incubation and washing procedures. In the modified experimental approach native whole blood is incubated for 15 min with an increased amount of thiazole orange (1 microg/ml) in the presence of phycoerythrin labeled antibodies directed against the constitutively surface expressed antigen GPlb. Data acquisition on the flow cytometer can be started immediately after stopping and stabilization of the reaction by paraformaldehyde fixation. Thiazole orange fluorescence was not significantly changed in thrombin-activated, degranulated platelets compared to resting platelets indicating no significant non-specific staining of platelet granules under the selected test conditions. In addition, experiments employing RNAse digestion demonstrated specificity of thiazole orange staining for platelet RNA.
The gene frequency of the most important hemoglobin (Hb) abnormalities is reported in a population of 171 Togolese newborns. Hb phenotypes, hematological parameters, and the more frequently described alpha-gene deletions were analyzed. Structural abnormalities of beta-globin were observed in 35.7% of the children with a gene frequency of 0.105 for beta(S) and 0.091 for beta(C). The frequency of the different alpha-globin genotypes was alpha alpha/ = 0.71, -alpha/ = 0.28, and alpha alpha alpha/ = 0.01. All of the individuals homozygous for the -alpha genotypes, and most of the heterozygous individuals, carried Hb Bart's. Within the alpha alpha/alpha alpha and the -alpha/alpha alpha groups, several individuals with or without Hb Bart's were found; they did not differ from the others by their red blood cell (RBC) parameters but by their levels of fetal hemoglobin (Hb F). The African alpha2 polymorphism marker, characterized by the replacement of G by TCGGCCC at position 7238 (EMBL HSHBA4, 1993) and of T 7174 by G, was found in 21 newborns. The mean value of Hb F was calculated for each genotype, the mean (G)gamma percentage was 69.4 +/- 4.0%, and the gene frequency of the AgammaT marker was 0.10; this marker was linked to the normal beta-globin cluster.
Quadruples of skin cancer patients with and without psoriasis and referents with and without psoriasis (4 x 20 study persons) were identified and examined for DNA damage by single cell gel electrophoresis (comet-assay) and DNA-repair by UV-induced unscheduled DNA synthesis (UDS) in mononuclear blood cells (lymphocytes and monocytes). DNA damage (strand breaks and alkaline labile sites) as assessed by the comet assay and DNA repair as assessed by UDS were significantly associated with the season in which blood sampling took place. This variation might be explained by an increased exposure to solar radiation. When the comet tail moment data were stratified by sampling period, an interaction between psoriasis and skin cancer was detected, with patients with psoriasis and skin cancer exhibiting more DNA damage. Patients with psoriasis and skin cancer also had lower UDS compared to healthy study persons, suggesting that the more DNA damage may be caused by a lower rate of DNA repair. In all study persons, the extent of UDS correlated positively with the amount of DNA damage determined by the comet assay.