Incomplete antigenic cross-reactivity between platelets and megakaryocytes: relevance to ITP

Immune thrombocytopenias are usually associated with normal or increased numbers of megakaryocytes in the marrow. Therefore, the mechanism(s) responsible for the destruction of circulating platelets may not affect megakaryocytes in the same way. One of the possibilities which could account for the differential effect on the cells would be the development of antibodies to components of platelet membranes which are not exposed on the surface of all megakaryocytes. To investigate this possibility, a rabbit antiserum specific for mouse platelets was tested against fresh and cultured mouse megakaryocytes by indirect immunofluorescence. This antiserum cross-reacted with 46% of fresh murine megakaryocytes and 54% of cultured megakaryocytes. Phase- contrast microscopy revealed the reacting megakaryocytes to be fully granulated with irregular contours and in the process of releasing platelets. Nonreactive megakaryocytes demonstrated smooth contours and lacked morphological evidence of thrombocytopoiesis. Electron microscopy showed that only in megakaryocytes (MK) with an irregular contour had the demarcation membrane system (DMS) reached continuity with the plasma membrane. Ultrastructural analysis of megakaryocytes from patients with ITP showed approximately 25% to 50% of megakaryocytes without evidence of injury, whereas 50% to 75% had extensive damage. In undamaged cells, platelet territories had not yet reached the peripheral zone. The DMS of damaged megakaryocytes opened to the exterior elaborating platelets. The observations suggested that some platelet antibodies react only with megakaryocytes which have reached the stage of thrombocytopoiesis. Relevant target antigens may not be exposed on all megakaryocytes before cytoplasmic fragmentation occurs.     

Important landmarks and distances for posterior fossa surgery measured by temporal MDCT

Neurosurgical Review - In this retrospective study, we aimed to present important anatomical structures and distances for posterior fossa surgery by temporal multidetector computed tomography...     

Effects of storage on the binding of carboplatin to plasma proteins

Plasma ultrafiltrates are routinely used in pharmacokinetic studies of carboplatin. Experiments were performed to detect and quantitate artifactual decreases in the platinum concentration of ultrafiltrates prepared from plasma samples stored at –20°C and –70°C. Carboplatin was added to anticoagulated, whole human blood to produce a 20 g/ml concentration. Plasma produced from the blood was stored frozen at either –20°C or –70°C. Aliquots from each storage condition were thawed and ultrafiltered once a week for up to 100 days. Platinum concentrations in ultrafiltrates and plasma were determined by flameless atomic absorption spectrometry. There was no loss of ultrafilterable platinum in plasma samples stored at –70°C, whereas there was a steady decrease in free platinum concentration in ultrafiltrates prepared from plasma samples stored at –20°C. These results imply that pharmacokinetic studies of carboplatin should use ultrafiltrates prepared immediately or that plasma for such studies should be stored at –70°C. Storage of carboplatincontaining plasma at –20°C and subsequent ultrafiltration is not acceptable, because measurement of platinum in such ultrafiltrates will be artifactually low.     

Therapeutic and experimental therapeutic studies on acupuncture and itch: review of the literature

Itch accompanies most inflammatory skin diseases but may occur as a solitary sensation in otherwise normal skin. Chronic itch often requires combined treatments but some cases remain therapy resistant. Complementary medicine is becoming increasingly popular among patients. Acupuncture is the oldest and most well‐studied alternative option with evidence‐based effect on pain. This article summarizes the rational for the use of acupuncture in treatment of itch and reviews therapeutic and experimental therapeutic studies on acupuncture and itch.     

Comparison of biomechanical behaviour of maxilla following Le Fort I osteotomy with 2- versus 4-plate fixation using 3D-FEA: Part 2: Impaction surgery

The aim of the second part of this study was to evaluate the mechanical behaviour of 2- versus 4-plate fixation and bony structures after Le Fort I impaction surgeries using three-dimensional finite element analysis (3D-FEA). Two 3D-FEA models were created to fixate the impacted maxilla at the Le Fort I level as 2-plate fixation at the piriform rims (IMP-2 model) and 4-plate fixation at the zygomatic buttresses and piriform rims (IMP-4 model). The IMP-2 model contained 225 664 elements and 48 754 nodes and the IMP-4 model consisted of 245 929 elements and 53 670 nodes. The stresses in each maxillary model were computed. The models were loaded on one side, at the molar–premolar region, in vertical, horizontal and oblique directions to reflect the chewing process.It was concluded that the use of 4-plate fixation following Le Fort I advancement surgery provides fewer stress fields on the maxillary bones and fixation materials than 2-plate fixation from a mechanical point of view.     

Partial chimerism after T-cell-depleted allogeneic bone marrow transplantation in leukemic HLA-matched patients: a cytogenetic documentation

We evaluated serially by cytogenetics the blood and marrow chimerism of 38 leukemic recipients of HLA-matched bone marrow transplants (BMT) who were prepared by high doses of alkylating agents and fractionated total- body irradiation (2.2 Gy X 5). Donor or host mitoses were identified by examination of sex chromosomes in 32 patients or by evaluation of the polymorphism of other chromosomes after specific banding in six patients. Twenty-four patients were recipients of untreated BMT, and 14 were recipients of T-cell-depleted BMT. In the 24 patients who received untreated BMT, all showed successful engraftment, and only three had a transient mixed chimera. In the 14 recipients of T-cell-depleted BMTs, four rejected their grafts, and seven had mixed chimeras; these mixed chimeras were more frequent in blood lymphocytes than in marrow cells and could be detected up to 26 months after BMT. This high frequency of partial chimerism after T-cell-depleted BMT by comparison with a control group suggests that the donor's T cells play an important role in the eradication of host residual hematopoiesis after allogeneic BMT.