FLT3 receptor expression on the surface of normal and malignant human hematopoietic cells

FLT3 ligand is a hematopoietic growth factor that plays a key role in growth of primitive hematopoietic cells. FLT3 receptor mRNA is found in early hematopoietic progenitors and in human myeloid leukemia blasts. Much less is known about the surface expression of FLT3 receptor on human hematopoietic cells. Using human 125I-FLT3 ligand, we have identified and characterized surface FLT3 receptors on normal and malignant human hematopoietic cells and cell lines. Our results showed that surface display of FLT3 receptor was greatest in fresh myeloid leukemia blast cells and myeloid leukemia cell lines. Erythroleukemic and megakaryocytic leukemia cell lines (n = 5) bound little to no 125I- FLT3 ligand. Scatchard analysis of 125I-FLT3 ligand binding data shows that three myeloid leukemia cell lines, ML-1, AML-193, and HL-60, as well as normal human marrow mononuclear cells, exhibit high affinity FLT3 receptors. Crosslinking of 125I-FLT3 ligand to FLT3 receptors on the surface of ML-1 myeloid leukemia cells indicates that the FLT3 ligand. The rates of FLT3 ligand internalization and degradation were determined by binding 125I-FLT3 ligand to ML-1 cells and acid stripping to distinguish surface bound from internalized ligand. Internalized 125I-FLT3 ligand was detected within 5 minutes after binding to ML-1 cells. In addition, we evaluated the effect of FLT3 ligand on megakaryocytic colony growth and nuclear endoreduplication, alone or in the presence of thrombopoietin. FLT3 ligand did not promote colony forming unit megakaryocyte (CFU-Meg) colony growth or megakaryocyte nuclear maturation, nor did FLT3 ligand augment the effects of thrombopoietin on these measures of megakaryopoiesis. These data indicate that the FLT3 receptor shares several characteristics with the c-kit receptor including dimerization and rapid internalization. However, the more restricted cellular distribution of the FLT3 receptor may target the effects of FLT3 ligand to primitive hematopoietic cells and to myeloid and lymphoid progenitor cells, in contrast to the pleiotropic effects of the c-kit receptor ligand, stem cell factor.     

The influence of a hydrogen peroxide and glycerol containing mouthrinse on plaque accumulation: a 3-day non-brushing model

Abstract: Aim: To evaluate the inhibition of plaque growth by an experimental mouthrinse (BioXyl^®) based on hydrogen peroxide/glycerol. Design: It was a double‐blind, randomized study involving 40 volunteers in good general health. At the start of the trial, all participants received a dental prophylaxis to remove all plaque deposits. During the next 3 days subjects refrained from any mechanical oral hygiene procedure, except for the allocated mouthrinse being either the hydrogen peroxide (H₂O₂; 0.013% H₂O₂/0.004% glycerol) or the placebo without H₂O₂. At the third day of appointment, plaque levels were assessed at six sites per tooth. Results: The test group had a mean overall plaque score of 2.66 and the placebo group of 2.70. The difference in plaque scores between the two groups was not statistically significant. Conclusions: The results of this pilot study showed that there was no statistically significant difference between the H₂O₂/glycerol group and the placebo group with respect to plaque inhibition within this study design.     

Physiologic features of hemolysis axxociated with altered cation and 2,3-diphosphoglycerate content

A hemolytic disorder characterized by altered RBC cation composition (increases Na, decreases K), reduced monovalent cation content (decreased Na + K/liter RBC), and decreased levels of 2,3- diphosphoglycerate (2,3-DPG) is described. The etiology of these RBC abnormalities was not elucidated following extensive laboratory evaluation, although two important physiologic principles were manifested by this case: (1) Hemolysis was relatively well compensated (41% hematocrit) despite a significantly decreased RBC survival (51 Cr t 1/2 = 10.5 days). This effect presumably was due to reduced 2,3-DPG content (1.9 mumol/ml RBC) and the associated increase in whole blood oxygen affinity (P50 = 19.6 mm hg). (2) RBC size and water content were normal in spite of marked cation depletion. This anomaly was thought to reflect the osmotic effects of reduced polyvalent anion (2,3-DPG) content.     

Appendiceal intussusception mistaken for a polyp at colonoscopy: case report and review of literature

We report a case of appendiceal intussusception which was erroneously labelled as a 10-mm polypoid caecal lesion on colonoscopy and, therefore, followed up over an 11-year period before the correct diagnosis was made. We present the radiological and endoscopic appearance of appendiceal intussusception and a review of the literature.