The heterogeneity of the gamma-chain of fetal hemoglobin in HbS heterozygotes

The relative quantities of the three types of gamma chain (G gamma, A gamma I, A gamma T) were determined in 18 AS parents of selected SS patients, in 15 additional HbS heterozygotes, as well as in additional SS patients, and in 35 SS and 24 AS newborn babies. The low amount of HbF in all AS adults (less than 1%) made it necessary to further improve the isolation procedure of HbF, which was accomplished by introducing an HPL chromatographic method. The additional data for older SS patients confirmed the existence of two groups characterized by either low G gamma (40%) or high G gamma (60%) values in their HbF. A distinction into "high G gamma" and "low G gamma" producers could also be made for HbS heterozygotes. Family studies, however, make it unlikely that the "high G gamma" condition is inherited in a simple mendelian fashion assuming a change in a regulatory mechanism. The presence of the A gamma T mutation, occurring either in cis or in trans to the beta S mutation, has been used to evaluate the possible contribution by specific gamma-chain genes to the gamma-chain composition of the HbF of adult AS persons. No clear pattern because evident, suggesting that most of the gamma-chain of this small amount of HbF could originate from gamma-chain genes in cis or in trans to the beta S gene or from both sets of genes. It is speculated that heterogeneity among "F-cells" may be a primary cause of the observed differences in gamma-chain composition of HbF in HbS heterozygotes.     

Impact of New Scatter Correction Strategies on High-Resolution Research Tomograph Brain PET Studies

Purpose

The aim of this study is to evaluate the impact of different scatter correction strategies on quantification of high-resolution research tomograph (HRRT) data for three tracers covering a wide range in kinetic profiles.

Procedures

Healthy subjects received dynamic HRRT scans using either (R)-[¹¹C]verapamil (n?=?5), [¹¹C]raclopride (n?=?5) or [¹¹C]flumazenil (n?=?5). To reduce the effects of patient motion on scatter scaling factors, a margin in the attenuation correction factor (ACF) sinogram was applied prior to 2D or 3D single scatter simulation (SSS).

Results

Some (R)-[¹¹C]verapamil studies showed prominent artefacts that disappeared with an ACF-margin of 10 mm or more. Use of 3D SSS for (R)-[¹¹C]verapamil showed a statistically significant increase in volume of distribution compared with 2D SSS (p?<?0.05), but not for [¹¹C]raclopride and [¹¹C]flumazenil studies (p?>?0.05).

Conclusions

When there is a patient motion-induced mismatch between transmission and emission scans, applying an ACF-margin resulted in more reliable scatter scaling factors but did not change (and/or deteriorate) quantification.

     

Sustained extracellular signal-regulated kinase1/2 mitogen-activated protein kinase signalling is related to increased p21 expression in cholesteatoma epithelium

CONCLUSION: These results show for the first time that the RAS/RAF/ERK1/2 MAPK signalling pathway is active and involved in p21-mediated cell cycle arrest in human cholesteatoma epithelium. OBJECTIVE: In a previous report we have demonstrated that the epithelium in human cholesteatoma is characterized by high p53-dependent p21 expression. The RAS/RAF/extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) signalling pathway can induce p21 expression and subsequent cell cycle arrest via p53-dependent or -independent mechanisms. We designed the present study to investigate whether the RAS/RAF/ERK1/2 MAPK signalling pathway is involved in p53-dependent and p21-mediated cell cycle arrest in human cholesteatoma. MATERIAL AND METHODS: A total of 18 cholesteatoma samples and 18 paired control retro-auricular skin samples were immunohistochemically stained for p53, p21, phosphorylated ERK1/2 (pERK1/2) and total ERK1/2. Positive cells were counted by means of digital image analysis. Double-label fluorescence immunohistochemistry was performed to demonstrate co-expression of p21 and pERK1/2. RESULTS: Protein expression of p53, p21 and pERK1/2 differed significantly between cholesteatoma epithelium and retro-auricular skin (p <0.01). In cholesteatoma, co-expression of p21 and pERK1/2 was prominent, whereas in retro-auricular skin there was hardly any co-expression. Positive correlations were found between p53 and p21 (p =0.003) and between p21 and pERK1/2 (p =0.013).     

Adverse effect of severe marrow fibrosis on hematologic recovery after chemoradiotherapy and allogeneic bone marrow transplantation

We reviewed the records and marrow biopsy specimens of 75 patients with leukemic, myelodysplastic, or myeloproliferative disorders to determine whether the presence of marrow fibrosis affected engraftment after allogeneic marrow transplantation. While 28 control patients without fibrosis achieved prompt engraftment, two of 32 patients (6%) with mild and five of 15 patients (33%) with severe fibrosis failed. The rate of myeloid recovery was significantly slower and the dependence on platelet and red blood cell transfusions was significantly longer in patients with severe fibrosis than in patients with no fibrosis. A finding of severe marrow fibrosis should therefore be taken into account when evaluating the risks and benefits of marrow transplantation.     

SOS chromotest, a direct assay of induction of an SOS function in Escherichia coli K-12 to measure genotoxicity.

We present and evaluate the SOS chromotest, a bacterial test for detecting DNA-damaging agents. It is a colorimetric assay based on the induction by these agents of the SOS function sfiA, whose level of expression is monitored by means of a sfiA::lacZ operon fusion. The response is rapid (a few hours), and does not require survival of the tester strain. Dose-response curves for various chemicals include a linear region. The slope of this region is taken as a measure of the SOS inducing potency. Comparison for a number of substances of known genotoxicity of the SOS inducing potency determined in the SOS chromotest with the mutagenic potency determined in the Salmonella assay (mutatest) revealed a striking quantitative correlation over more than 7 orders of magnitude. The sensitivity of the SOS chromotest (lowest amount detected) is equal to that of the mutatest and generally 4-40 times higher than that of a phage induction assay (inductest). From a practical point of view our observations contribute to the validation of the SOS chromotest as a test for detecting genotoxins and in particular genotoxic carcinogens. From a theoretical standpoint the results suggest that mutagenic potency measured in the mutatest reflects the level of induction of an SOS function and that most genotoxins are inducers of the SOS response in bacteria.