Fragmented Erythrocytes Research Articles

Segmental Heterogeneity of Vasa Vasorum Neovascularization in Human Coronary Atherosclerosis

Our aim was to investigate the role of coronary vasa vasorum (VV) neovascularization in the progression and complications of human coronary atherosclerotic plaques. Accumulating evidence supports an important role of VV neovascularization in atherogenesis and lesion location determination in coronary artery disease. VV neovascularization can lead to intraplaque hemorrhage, which has been identified as a promoter of plaque progression and complications like plaque rupture. We hypothesized that distinctive patterns of VV neovascularization and associated plaque complications can be found in different stages of human coronary atherosclerosis. Hearts from 15 patients (age 52+/-5 years, mean+/-SEM) were obtained at autopsy, perfused with Microfil (Flow Tech, Inc., Carver, Massachusetts), and subsequently scanned with micro-computed tomography (CT). The 2-cm segments (n=50) were histologically classified as either normal (n=12), nonstenotic plaque (<50% stenosis, n=18), calcified (n=10) or noncalcified (n=10) stenotic plaque. Micro-CT images were analyzed for VV density (number/mm2), VV vascular area fraction (mm2/mm2), and VV endothelial surface fraction (mm2/mm3). Histological sections were stained for Mallory's (iron), von Kossa (calcium), and glycophorin-A (erythrocyte fragments) as well as endothelial nitric oxide synthase, vascular endothelial growth factor, and tumor necrosis factor-alpha. VV density was higher in segments with nonstenotic and noncalcified stenotic plaques as compared with normal segments (3.36+/-0.45, 3.72+/-1.03 vs. 1.16+/-0.21, p<0.01). In calcified stenotic plaques, VV spatial density was lowest (0.95+/-0.21, p<0.05 vs. nonstenotic and noncalcified stenotic plaque). The amount of iron and glycophorin A was significantly higher in nonstenotic and stenotic plaques as compared with normal segments, and correlated with VV density (Kendall-Tau correlation coefficient 0.65 and 0.58, respectively, p<0.01). Moreover, relatively high amounts of iron and glycophorin A were found in calcified plaques. Further immunohistochemical characterization of VV revealed positive staining for endothelial nitric oxide synthase and tumor necrosis factor-alpha but not vascular endothelial growth factor. Our results support a possible role of VV neovascularization, VV rupture, and intraplaque hemorrhage in the progression and complications of human coronary atherosclerosis.

Reversible posterior leukoencephalopathy syndrome (RPLS)を呈した血栓性血小板減少性紫斑病

A 48-year-old man presented with consciousness disturbance with vasogenic edema in the occipital lobe on brain CT. The diagnosis of reversible posterior leukoencephalopathy syndrome (RPLS) was made. His hypertension was refractory to treatment, and his neurological disabilities and CT abnormalities, along with renal dysfunction, became worse. Hemodialysis and strict management of blood pressure resolved the neurological findings and the lesions on brain CT. However, one week later, consciousness disturbance and brain CT abnormalities recurred. At that time, hemolytic anemia with fragmented erythrocytes, thrombocytopenia, and renal dysfunction became apparent. We therefore diagnosed thrombotic thrombocytopenic purpura (TTP). Plasma exchange and vincristine administration improved not only the clinical findings of TTP, but also consciousness disturbance and brain CT abnormalities. We concluded that latent TTP had caused RPLS in this patient.

Hemolytic anemia in a patient with hypertrophic obstructive cardiomyopathy

A 66-year-old woman was referred for further evaluation and treatment of normocytic and normochromic anemia with hemoglobin level of 8.6 g/dL. A peripheral blood smear showed fragmented erythrocytes. The patient was then referred to the department of cardiology because of systolic murmur, ECG abnormality, and red cell fragmentation. Transthoracic echocardiography revealed hypertrophic cardiomyopathy with particularly increased interventricular septal thickness of 24 mm and a hyperkinetic wall motion, resulting in marked obstruction to left ventricular outflow tract (pressure gradient of 200 mmHg). Mitral regurgitation due to systolic anterior motion of the mitral valve leaflets was also seen. The cause of anemia was thought to be mechanical intravascular hemolysis due to left ventricular outflow tract obstruction and mitral regurgitation. She was treated with atenolol and the class Ia antiarrhythmic drug cibenzoline to relieve the outflow tract obstruction, and the pressure gradient was reduced to 70 mmHg. After 3 months of treatment, her hemoglobin level had increased to 11.4 g/dL without additional treatment for anemia.

Circulating siderophagocytes and erythrophagocytes in a corn snake (Elaphe guttata) after coelomic surgery

Leukocytes containing nonheme iron and phagocytosed fragments of erythrocytes were found in blood smears from a corn snake (Elaphe guttata) collected 20 and 79 days after coelomic surgery (ovariosalpingectomy). Numerous immature and mitotic erythrocytes also were seen in the sample taken 20 days postsurgically. Siderophagocytes and erythrophagocytes had not been observed before surgery and were not found in multiple subsequent blood samples collected 112-602 days after surgery. Other than these hematologic abnormalities, laboratory findings were unremarkable and the snake recovered uneventfully. Based on examination of sequential blood smears, the circulating siderophagocytes were interpreted as recirculating macrophages involved in the removal of blood from the coelomic cavity after mild postsurgical hemorrhage.

Thrombotic microangiopathy after treatment with bortezomib and dexamethasone in a patient with multiple myeloma

Bortezomib (Bz) is extensively used for treating patients with multiple myeloma. There has been an accumulation of information on its efficacy and safety. Thrombotic disorders after treatment with Bz are rare, except for complication caused by tumor lysis syndrome. Here, we report a rare case of thrombotic microangiopathy (TMA) after treatment with Bz and dexamethasone (Dexa) in a patient with multiple myeloma. A 54-year-old Japanese man with refractory IgAjtypemultiple myeloma was treated with Bz (1.3 mg/m, days 1, 4, 8, and 11 in 21-day cycles) and Dexa (20 mg/body, days 1, 2, 4, 5, 8, 9, 11, and 12) in November 2007. He had received high-dose melphalan with autologous peripheral blood stem cell transplantation in May 2005 and allogeneic bone marrow transplantation after a reduced-intensity conditioning regimen [fludarabine, busulfan, and 4 Gy of total body irradiation (TBI)] in November 2006. He had dry skin and bronchiolitis obliterans organizing pneumonia (BOOP) caused by chronic graft-versus-host disease (GVHD), and he was treated with oral tacrorimus (1.2 mg/ day) and prednisolone (10 mg/day) and showed improvement. He had not had TMA, thrombotic thrombocytoprnic purpura (TTP), hemolytic uremic syndrome (HUS) or veno-occlusive-disease (VOD). The patient complained of chest pain and dyspnea on the fifth day in the first course of treatment with Bz and Dexa. His oxygen saturation (SpO2) was 88% in room air. Computed tomography of the chest showed ground glass opacities throughout the bilateral upper and middle lobes (Fig. 1). He suffered from severe interstitial pneumonia (IP). Since we thought that Bz was the cause of his pneumonia, we administered methylpredonisolone at 1,000 mg/ body intravenously for 3 days and stopped the treatment with Bz and Dexa. His pneumonia improved rapidly and did not recur despite steroid tapering off. Three days after the onset of IP (first course, day 8), he had scattered petechiae and suggillation. His consciousness was clear and vital signs were normal. Results of laboratory tests are shown in Tables 1 and 2. Anemia and thrombocytopenia had progressed, and aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and indirect bilirubin were elevated and haptoglobin was decreased. Coombs test results were negative. Erythrocyte fragmentation ratio was 12.7% (Fig. 2). These data suggested microangiopathic hemolytic anemia. Decreased fibrinogen and extended prothrombin time observed by coagulation tests appeared 2 days before this event. Activity of ADAMTS-13 was slightly low (Table 2) and an inhibitor of ADAMTS-13 was not detected. Cytomegalovirus antigens were not detected, and beta-D-glucan, candida antigens and aspergillus antigens were normal. Bacterial cultures in sputa, stools, and urine were negative. We thought he suffered from TMA and administered fresh frozen plasma (240 ml/day) and haptoglobin (2,000 U/day). His symptoms improved gradually. Within 20 days, his laboratory data returned to the levels before treatment with Bz and Dexa. TMA is thought to be caused by endothelial damage derived from high-dose chemotherapy, TBI, GVHD, immunosuppressive agents and opportunistic infections in R. Morita (&) S. Hashino S. Shirai N. Fujita M. Onozawa K. Kahata T. Kondo M. Asaka Department of Gastroenterology and Hematology, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo 060-8638, Japan e-mail: r-mori@f3.dion.ne.jp

Review of idiopathic eosinophilic meningitis in dogs and cats, with a detailed description of two recent cases in dogs : review and clinical communication

Eosinophilic meningoencephalitis (EME) has been described in various species of animals and in humans. In dogs it has been associated with protozoal infections, cuterebral myiasis and various other aetiologies. Ten cases of idiopathic eosinophilic meningoencephalitis have been reported in dogs and one in a cat where the origin was uncertain or unknown. The dogs were all males, of various breeds but with a predominance of Golden Retrievers and Rottweilers; they generally had a young age of onset. Two cases with no apparent underlying aetiology were diagnosed on post mortem examination. The 18-month-old, male Boerboel presented with sudden onset of cerebellar ataxia, as well as various asymmetrical cranial nerve deficits of 2 weeks' duration and without progression. Haematology revealed a peripheral eosinophilia. Necropsy showed extreme generalised congestion especially of the meninges and blood smear and histological sections of various tissues showed intravascular erythrocyte fragmentation with the formation of microcytes. Histopathology revealed severe diffuse cerebrocortical subarachnoidal meningitis and submeningeal encephalitis, the exudate containing variable numbers of eosinophils together with neutrophils and mononuclear cells. There was also deeper white matter and hippocampal multifocal perivascular mononuclear encephalitis and multifocal periventricular malacia, gliosis and phagocytosis of white matter. The cerebellum, brain stem and spinal c showed only mild multifocal oedema or scattered occasional axon and myelin degeneration respectively, with no inflammation. Immunohistochemical staining of central nervous tissue for Toxoplasma gondii failed to show any antigen in the central nervous tissue. Ultrastructure of a single submeningeal suspected parasitic cyst showed it to be chromatin clumping within a neuron nucleus indicating karyorrhexis. Gram stain provided no evidence of an aetiological agent. The 3-year-old Beagle bitch had a Caesarian section after developing a non-responsive inertia 8 days prior to presentation. This animal's clinical signs included status epilepticus seizures unrelated to hypocalcaemia and warranted induction of a barbiturate coma. She died 4 hours later. Post mortem and histopathological findings in the brain were almost identical to those of the Boerboel and she also showed histological evidence of recent active intravascular haemolysis with microcyte formation. Rabies, distemper and Neospora caninum immunohistochemical stains were negative in the brains of both dogs. Immunohistochemical staining of the cerebral and meningeal exudates of the Beagle for T- and B-lymphocyte (CD3 and CD79a) markers showed a predominance of T-lymphocytes with fewer scattered B lymphocytes. A possible allergic response to amoxicillin/clavulanate is considered, as this appeared to be the only feature common to the recent history of both animals. An overview of EME in humans, dogs and cats is given and the previously published cases of idiopathic EME in dogs and the single published cat case are briefly reviewed.

Dematin and Adducin Provide a Novel Link between the Spectrin Cytoskeleton and Human Erythrocyte Membrane by Directly Interacting with Glucose Transporter-1

Dematin and adducin are actin-binding proteins located at the spectrin-actin junctions, also called the junctional complex, in the erythrocyte membrane. Here we propose a new model whereby dematin and adducin link the junctional complex to human erythrocyte plasma membrane. Using a combination of surface labeling, immunoprecipitation, and vesicle proteomics approaches, we have identified glucose transporter-1 as the receptor for dematin and adducin in the human erythrocyte membrane. This finding is the first description of a transmembrane protein that binds to dematin and adducin, thus providing a rationale for the attachment of the junctional complex to the lipid bilayer. Because homologues of dematin, adducin, and glucose transporter-1 exist in many non-erythroid cells, we propose that a conserved mechanism may exist that couples sugar and other related transporters to the actin cytoskeleton.

Significance of hemorrhagic endovasculitis in placentae from stillbirths

Hemorrhagic endovasculitis (HEV) is an alteration of fetal chorionic blood vessels within the placenta. This disruption of the integrity of the parietal blood vessels has been reported in association with poor pregnancy outcomes and perinatal complications. In stillbirths, its presence has been implicated as part of the mechanism of the cessation of fetal circulation in postmortem retention of the placenta. The purpose of this study was to give an interpretation of this type of blood vessel damage: whether it is related to the arrest of blood circulation after stillbirth, or whether it constitutes an alteration of the integrity of placental chorionic circulation contributing to the death of the fetus. From 1232 reviewed placentae, we analyzed 46 cases with HEV, 70% from livebirths and 30% from stillbirths. The most frequent lesions encountered in placentae were categorized microscopically. The distribution of these lesions in placentae from livebirth and stillbirth pregnancies was then described. In association with HEV, villitis of unknown etiology and chorionic vessel thrombi occurred more frequently in placentae from livebirths. Fragmented erythrocytes and erythroblasts were more frequent in placentae from stillbirths. Our study demonstrates that HEV is more consistently associated with other placental lesions in liveborn than in stillborn infants.

Hemosiderin-Laden Macrophages in the Cerebrospinal Fluid of a Neonate After Traumatic Lumbar Puncture

Macrophages in cerebrospinal fluid are described as indicators of pathology. We present findings from the lumbar puncture of a child without neurologic disease. Cerebrospinal fluid obtained after an initial, traumatic lumbar puncture attempt included a high proportion of macrophages, some containing erythrocyte fragments and hemosiderin. This suggests that although macrophages may indicate pathology, they can also accumulate after traumatic lumbar puncture.

Hemolytic uremic syndrome following Hemiscorpius lepturus (scorpion) sting

Scorpion envenomations are a public health problem in many countries. Scorpions are second only to snakes in causing human fatalities from envenomation. Species of scorpions capable of inflicting fatal stings are living in North and South Africa, the Middle East, India, America, Trinidad, and Tobago. Hemiscorpius lepturus (from the Hemiscorpiidae family) is the most medically important scorpion in Iran which accounts for 92% of all hospitalized scorpion sting cases. The venom from H. lepturus is primarily a cytotoxic agent and has hemolytic, nephrotoxic, and to some extent, hepatotoxic activities. We found a combination of microangiopatic hemolytic anemia, thrombocytopenia, and acute renal failure in a seven year-old female child who was referred to us with a 12 h history of bloody urine following a H. lepturus sting. Her blood smear showed fragmented erythrocytes and burr cells, leading us to a diagnosis of hemolytic uremic syndrome (HUS). This report highlights the importance of acceptable prophylaxis and therapeutic protocols for HUS in these patients.

Hemoglobin Hagley Park: A Novel (α82Ala→Thr) Substitution Identified in an Infant with Severe Hemolytic Anemia

The identification of new hemoglobin mutations and the correlation of structural changes with potential pathology continue to provide insights into how normal structure and function are preserved in the tetrameric molecule. Hematological investigation of a 6-week-old infant with severe hemolytic anemia revealed a decreased hemoglobin concentration of 53 g/L, a decreased hematocrit of 0.15, and a decreased erythrocyte count of 1.8 × 1012/L. In addition the infant had an increase in reticulocytes (322 × 109/L) and bilirubin (96 μmol/L). Blood films showed a normochromic picture with irregularly shaped cells, elliptocytes, and erythrocyte fragments suggestive of an erythrocyte membrane defect. G6PD and pyruvate kinase concentrations were within reference intervals, and a presumptive diagnosis of hereditary elliptocytosis was made. Cellulose acetate and citrate agar electrophoresis results were both within reference intervals, as was cation exchange chromatography on the Bio-Rad Variant β-thalassemia system. Examination of whole lysate by electrospray ionization mass spectrometry on a VG Platform (1) showed that the complement of β (15 867 Da), γG (15 995 Da), and γA (16 010 …

Combined Deletion of Mouse Dematin-Headpiece and β-Adducin Exerts a Novel Effect on the Spectrin-Actin Junctions Leading to Erythrocyte Fragility and Hemolytic Anemia

Dematin and adducin are actin-binding proteins of the erythrocyte "junctional complex." Individually, they exert modest effects on erythrocyte shape and membrane stability, and their homologues are expressed widely in non-erythroid cells. Here we report generation and characterization of double knock-out mice lacking beta-adducin and the headpiece domain of dematin. The combined mutations result in altered erythrocyte morphology, increased membrane instability, and severe hemolysis. Peripheral blood analysis shows evidence of severe hemolytic anemia with reduced number of erythrocytes/hematocrit/hemoglobin and an approximately 12-fold increase in the number of circulating reticulocytes. The presence of a variety of misshapen and fragmented erythrocytes correlates with increased osmotic fragility and reduced in vivo life span. Despite the apparently normal protein composition of the mutant erythrocyte membrane, the retention of the spectrin-actin complex in the membrane under low ionic strength conditions is significantly reduced by the double mutation. Atomic force microscopy reveals an increase in grain size and a decrease in filament number of the mutant membrane cytoskeleton, although the volume parameter is similar to wild type erythrocytes. Aggregated, disassembled, and irregular features are visualized in the mutant membrane, consistent with the presence of large protein aggregates. Importantly, purified dematin binds to the stripped inside-out vesicles in a saturable manner, and dematin-membrane binding is abolished upon pretreatment of membrane vesicles with trypsin. Together, these results reveal an essential role of dematin and adducin in the maintenance of erythrocyte shape and membrane stability, and they suggest that the dematin-membrane interaction could link the junctional complex to the plasma membrane in erythroid cells.

THROMBOTIC MICROANGIOPATHIES - AN ISSUE FOR INTENSIVISTS?

(2007). THROMBOTIC MICROANGIOPATHIES - AN ISSUE FOR INTENSIVISTS? Acta Clinica Belgica: Vol. 62, No. sup2, pp. 385-388.

Recurrent Idiopathic Thrombotic Thrombocytopenic Purpura: A Role for Vaccination in Disease Relapse?

The presence of antibodies against a disintegrin-like metalloproteinase with thrombospondin type 1 motif, isoform 13 (ADAMTS 13 protease) is the main cause (70% to 80%) of idiopathic and recurrent thrombotic thrombocytopenic purpura (TTP). However, etiologic factors that trigger the onset and potential relapses of TTP remain unclear. Immunologic deregulation and infectious agents are suspected. We report the case of a 51-year-old white man presenting with idiopathic TTP caused by autoantibodies against ADAMTS 13 protease. The first acute TTP episode needed long-term plasma exchanges because of early relapses. Consequently, vincristine therapy and splenectomy were performed. Those treatments induced TTP remission for 18 months. Relapses occurred twice between 1 and 3 months after vaccination. However, those relapses were not as severe as the first acute episode and responded to short-course plasma exchanges. ADAMTS 13 antibodies and decreased ADAMTS 13 protease activity were searched for and detected first during the second relapse. This case challenges the role of vaccination as an etiologic factor in the recurrence of idiopathic TTP.

Thrombotic microangiopathies: An update

Thrombotic microangiopathies (TMA) are microvascular occlusive disorders characterized by hemolytic anemia caused by fragmentation of erythrocytes and thrombocytopenia due to increased platelet aggregation and thrombus formation, eventually leading to disturbed microcirculation with reduced organ perfusion. Although several disease states may manifest as TMA, the two most relevant conditions associated with TMA are thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), characterized by prominent brain or renal lesions, respectively. However, occasionally the clinical distinction between these two conditions can be difficult. In this review, we focus on the epidemiologic and diagnostic criteria as well as on the most recent insights into the pathophysiology and treatment of these two conditions.

Suicidal death of erythrocytes in recurrent hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia with fragmented erythrocytes, thrombocytopenia, and acute renal failure. Lack of complement inactivating factor H predisposes to the development of atypical HUS. Little is known about mechanisms linking complement activation with loss of erythrocyte integrity during HUS. Recent studies disclosed that increased cytosolic Ca2+ activity and cellular ceramide trigger programmed erythrocyte death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the erythrocyte surface. In the present study, we investigated whether eryptosis occurs during the course of HUS. To this end, erythrocytes from healthy volunteers were exposed to plasma from a patient with severe idiopathic recurrent HUS secondary to factor H depletion. Phosphatidylserine exposure (Annexin binding), cell volume (forward scatter), cytosolic Ca2+ activity (Fluo3 fluorescence), and ceramide formation [anti-ceramide antibody and enzymatic (diacylgycerol kinase) analysis] were determined. Exposure of erythrocytes to plasma from the patient, but not to plasma from healthy individuals, triggered Annexin binding. The effect of plasma on erythrocyte Annexin binding was abolished by plasmapheresis or filtration at 30 kDa. It was paralleled by formation of ceramide and increase of cytosolic Ca2+ activity. Enhanced Annexin binding of erythrocytes from healthy individuals was observed after exposure to plasma from three other patients with HUS. The proeryptotic effect of patient plasma was mimicked by exposure to the Ca2+ ionophore ionomycin, and eryptosis was potentiated in the presence of cell membrane-permeable C6-ceramide. Furthermore, in vitro complement activation similarly triggered erythrocyte phosphatidylserine exposure, an effect which was blunted by the addition of factor H. In conclusion, our present observations disclose a novel, pathophysiological, factor-H dependent mechanism leading to injury of erythrocytes during the course of hemolytic uremic syndrome.

Renal Injury Is a Consistent Finding in Dutch Belted Rabbits Experimentally Infected with EnterohemorrhagicEscherichia coli

Enterohemorrhagic Escherichia coli (EHEC) produces Shiga toxin (Stx) and causes renal disease in humans. Dutch Belted (DB) rabbits naturally infected with EHEC O153 develop hemolytic-uremic syndrome-like disease. The aims of this study were to experimentally reproduce O153-induced renal disease in DB rabbits and investigate bacterial and host factors involved in pathogenesis. The pathogenicity of E. coli O157:H7 was also investigated in rabbits. The stx1AB region of O153 was sequenced. By use of liquid chromatography-tandem mass spectrometry, we identified homologs of the Stx receptor, globotriaosylceramide (Gb3), in rabbit kidney extracts. Infected rabbits developed clinical signs and intestinal and kidney lesions. Renal pathological changes consisted of intimal swelling, perivascular edema, erythrocyte fragmentation, capillary thickening, luminal constriction, leukocytic infiltration, mesangial deposits, and changes in Bowman's capsule and space. Sequence analysis of a approximately 7-kb region of the O153 chromosome indicated homology to the Stx1-producing bacteriophage H19B. Our findings indicate that DB rabbits are suitable for the study of the renal manifestations of EHEC infection in humans.

Familial Thrombotic Thrombocytopenic Purpura in Three Siblings.

Thrombotic thrombocytopenic purpura (TTP) is characterized by microangiopathic hemolytic anemia, systemic platelet aggregation, organ ischemia, thrombocytopenia, and fragmentation of erythrocytes. The disease is caused either by congenital deficiency of von Willebrand factor-cleaving protease (ADAMTS 13) or due to acquired autoantibodies against ADAMTS 13. We have been treating three siblings with recurrent episodes of hemolytic anemia, thrombocytopenia, neurological and renal dysfunctions during last 10 years. The oldest brother presented with thromboangiopathic anemia, thrombocytopenia (platelets account below 30x103/μl), episode of unconsciousness, proteinuria and splenomegaly at the age of 15 years. Splenectomy was done with the improvement in thrombocytopenic purpura. But he has suffered from permanent microangiopathic hemolytic anemia, and developed renal insufficiency. He died due to intestinal bleeding last year. Two younger siblings, a 12 year old girl and an 11 year old boy also presented with recurrent symptoms of microangipathic hemolytic anemia and thrombopcytopenia with or without renal dysfunction since early childhood. The diagnosis of congenital TTP in this family was based on clinical symptoms and tests of ADAMTS 13 and its inhibitor. The activity of ADAMTS 13 in two younger siblings performed according to the method of Gerritsen et al. was unmeasurable (<3%, reference range 30 – 120%). The ADAMTS 13 inhibitor was undetectable. Both patients are treated with fresh frozen plasma (FFP) infusions every 4 weeks. Precise diagnosis is very important for proper treatment. Only regular FFP infusions as ADAMTS 13 supplementation can assure normal health condition of children with familial TTP.

Simultaneous Loss of Mouse Dematin and beta-Adducin Results in Severe Erythrocyte Fragility and Hemolytic Anemia.

The mechanical strength and stability of the erythrocyte membrane are regulated by a network of proteins that participate in both horizontal and vertical interactions. The actin-containing junctional complexes, located at the tail ends of spectrin molecules, serve as the critical regulatory nodes for the maintenance of membrane stability. Dematin and beta-adducin, two actin-binding proteins of the junctional complex, are known to play essential roles in the regulation of erythrocyte shape and membrane stability, as revealed recently by the development of mouse knockout models. Here, we show that simultaneous loss of functional dematin (headpiece domain deletion) and beta-adducin results in severe fragility and abnormal shape of erythrocytes, despite the presence of major skeletal proteins. Adducin/Dematin Double Knockout (ADKO) mice are viable and can be distinguished at birth by their pallor with pronounced spleomegaly and regenerative hematopoiesis. Hematological evaluations show a reduction of erythrocytes, reduced hematocrit and hemoglobin, and a ~52% increase in the number of reticulocytes. The presence of a variety of misshapen and fragmented erythrocytes in the ADKO mice correlates with increased osmotic fragility and reduced erythrocyte life span in vivo. Despite an apparently normal composition of ghosts and skeletal proteins, the retention of spectrin in the ADKO erythrocyte plasma membrane is significantly compromised. Atomic force microscopy (AFM) revealed similar volume parameters in the four genotypes examined, but an increased grain size, and a decreased filament number in the ADKO erythrocyte membrane. In addition, highly aggregated, disassembled, and irregular features were visualized by AFM in the ADKO erythrocyte membrane. Staining of filamentous actin provided further evidence for the existence of large protein aggregates in the ADKO erythrocyte membrane. Together, these results demonstrate a crucial function of dematin and beta-adducin in the maintenance of erythrocyte shape and membrane stability, and more importantly, suggest the existence of an alternate mechanism for the linkage of junctional complexes to the plasma membrane.

Intestinal thrombotic microangiopathy following reduced-intensity umbilical cord blood transplantation

Thrombotic microangiopathy (TMA) is a significant complication after hematopoietic stem-cell transplantation (HSCT); however, there is little information on it following reduced-intensity cord blood transplantation (RI-CBT). We reviewed the medical records of 123 adult patients who received RI-CBT at Toranomon Hospital between January 2002 and August 2004. TMA was diagnosed in seven patients based on intestinal biopsy (n = 6) or autopsy results (n = 1). While these patients showed some clinical symptoms such as diarrhea and/or abdominal pain, mental status alterations or neurological disorders were not observed in any of them. Laboratory results were mostly normal at the onset of TMA; >2% fragmented erythrocytes (n = 1), <10 mg/dl haptoglobin (n = 1), and >200 IU/dl lactic dehydrogenase (LD) (n = 4). On endoscopic examination, TMA lesions, consisting of ulcers, erosions, and diffuse exfoliation, were distributed spottily from terminal ileum to rectum. Intestinal graft-versus-host disease (GVHD) and cytomegalovirus (CMV) colitis were confirmed in five and four patients, respectively. With therapeutic measures including supportive care (n = 4), fresh frozen plasma (n = 1), and a reduction of immunosuppressive agents (n = 1), TMA improved in four patients. The present study demonstrates that intestinal TMA is a significant complication after RI-CBT. Since conventional diagnostic criteria can overlook TMA, its diagnosis requires careful examination of the gastrointestinal tract using endoscopy with biopsy.