Kazuhiko Nakahara

Platelet-dependent thrombin generation in patients with diabetes mellitus: effects of glycemic control on coagulability in diabetes.

OBJECTIVESnThis study sought to assess the usefulness of platelet-dependent thrombin generation as an index of coagulability in diabetes and to determine the effect of glycemic control on coagulability in diabetes.nnnBACKGROUNDnIt is important to investigate the interaction of platelets and the coagulation factors to clarify the processes of the coagulation system in detail.nnnMETHODSnPlatelet-rich plasma (150 X 10(9)/liter), 0.5 ml, was prepared, and 40 mmol/liter of calcium chloride was added to initiate clotting. S-2238 was added to each sample in a microtiter plate every 10 min, and the absorbance of the released color product at 2 min was measured spectrophotometrically at a wavelength of 405 nm using a microtiter plate reader as thrombin generation. We measured the platelet-independent thrombin generation in patients with non-insulin-dependent diabetes mellitus grouped according to glycemic control.nnnRESULTSnPlatelet-dependent thrombin generation at 30 min after calcium chloride addition was significantly higher in 23 patients with poorly glycemic-controlled non-insulin-dependent diabetes mellitus without complications, such as diabetic retinopathy, nephropathy and neuropathy (hemoglobin [Hb] A1c >/= 9.0%) than in 46 healthy normal subjects (448 +/- 75 vs. 165 +/- 28 mU/min, p < 0.001). Thrombin generation in 31 well controlled diabetic patients without complications (Hb A1c < 9.0%) was intermediate (240 +/- 72 mU/min) between those of the poorly controlled group and healthy normal subjects. Platelet-poor plasma from diabetic patients increased platelet-dependent thrombin generation in normal subjects.nnnCONCLUSIONSnCoagulability is evidently enhanced in patients with non-insulin-dependent diabetes mellitus compared with that in healthy normal subjects on the basis of assessments of the platelet-dependent thrombin generation, and good glycemic control may help to correct a hypercoagulable state in diabetic patients.

GLUT2 expression in the rat retina: localization at the apical ends of Müller cells.

In order to understand the molecular basis of glucose regulation supporting visual function, this study examined the presence of GLUT2, a facilitated-diffusion glucose transporter isoform, and delineated its localization in the rat retina. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated the presence of GLUT2 mRNA, and immunoblot analysis using polyclonal antibody specific to rat GLUT2 revealed a band at a molecular weight of approximately 60 kDa, indicating the presence of GLUT2 protein in the rat retina. Fluorescence and electron microscopy localized GLUT2 expression to the apical ends of Müller cells that face the inter-photoreceptor space. These findings suggest that GLUT2 on Müller cells may control intra-retinal glucose homeostasis by performing both anterior and posterior glucose transport within the rat retina. This is the first study to provide evidence that GLUT2 is present in the mammalian central nervous system and indicates that GLUT2 may have local glucose homeostatic functions within the retina in addition to its role in the regulation of systemic blood glucose level.

Responsiveness of bone marrow erythroid progenitors (CFU‐E and BFU‐E) to recombinant human erythropoietin (rh‐Ep) in vitro in multiple myeloma

The responsiveness of bone marrow erythroid progenitors (CFU‐E and BFU‐E) to recombinant human erythropoietin (rh‐Ep) was investigated in vitro in 21 patients with multiple myeloma to assess the clinical usefulness of rh‐Ep in this disease. CFU‐E and BFU‐E assays were performed by methylcellulose culture methods. The myeloma patients were divided into two groups according to the percentage of plasma cells in the bone marrow (over 50% and under 50%). Among the patients with few plasma cells, some revealed normal CFU‐E and BFU‐E growth at 2 units of rh‐Ep, and no further increase was observed even with an increasing dose of rh‐Ep. Among the other patients, more than half demonstrated a good response to rh‐Ep. Among the patients with a high percentage of plasma cells, some revealed no response to rh‐Ep, but there were patients with a high percentage of plasma cells in the bone marrow who had a good response to rh‐Ep. High doses of rh‐Ep may be clinically effective in some patients with multiple myeloma independently of the level of plasma cells in the bone marrow.

Translin/TRAX Deficiency Affects Mesenchymal Differentiation Programs and Induces Bone Marrow Failure

The decision regarding self-renewal versus differentiation of hematopoietic stem cells (HSCs) is a crucial issue in bone marrow hematopoiesis. We have generated mice homozygous for an inactivating mutation of the whole Translin gene (Translin−/−) and investigated their hematopoietic status during early and later in life. Here we show that Translin deficiency affects mesenchymal differentiation and results in perturbation of self-renewal HSCs. Young Translin−/− mice, especially around 3 weeks of age, displayed markedly reduced lymphocyte counts in the peripheral blood, attributable to developmental arrest of B-lymphocytes in the earliest progenitor stage. With aging, progressive bone marrow failure was displayed, with developmental arrest of myeloid cells and B lymphocytes in a stroma-dependent manner, and eventually ectopic osteogenesis, vasculogenesis and adipogenesis resulted. Despite apparent hematopoietic aplasia, however, the frequency of HSCs in the bone marrow of mutant mice was remarkably increased. Furthermore, knockdown of Translin and its binding partner protein, TRAX, up-regulated genes associated with mesenchymal differentiation in a mesenchymal stem cell line. Taken together, these findings suggest that the Translin and TRAX complex influences both self-renewal and multilineage differentiation of HSCs by targeting mesenchymal stem/progenitor cells.

A case of POEMS syndrome with thrombocytopenia and biliverdinaemia

Summary This report describes a case of POEMS syndrome with extremely rare complications of thrombocytopenia and biliverdinaemia. The thrombocytopenia appeared to be due to immunopathogenesis. Steroid treatment resulted in complete disappearance of the biliverdinaemia in this patient as well as symptoms and signs of POEMS syndrome, suggesting that the biliverdinaemia was related to POEMS syndrome.