Morphopathological Effect of Ferrihydrite Nanoparticles in an Experimental Model of Toxic Hemolytic Anemia

We studied the effect of biogenic ferrihydrite nanoparticles synthesized as a result of the culturing of Klebsiella oxytoca on Wistar rats with experimental toxic hemolytic anemia. The pathology was simulated by single intraperitoneal injection of phenylhydrazine hydrochloride. On day 4, the functional parameters of erythrocytes in rats corresponded to the state of toxic hemolytic anemia. It is shown that ferrihydrite nanoparticles suspension has chronic toxicity and causes morphological changes in organs (mainly in the spleen), which are characterized by accumulation of nanoparticles. Administration of phenylhydrazine induced systemic vascular damage and the formation of extramedullary hematopoietic foci, which indicated a compensatory activation in hematopoiesis in the liver and spleen. Injection of nanoparticles reduced discirculatory and necrotic changes in the kidneys.

Erythrophagocytes in hemolytic anemia, wound healing, and cancer

Hemolysis is a ubiquitous pathology defined as premature red blood cell destruction within the circulation or local tissues. One of the most archetypal functions of macrophages is phagocytosis of damaged or extravasated red blood cells, preventing the extracellular release of toxic hemoglobin and heme. Upon erythrophagocytosis, spiking intracellular heme concentrations drive macrophage transformation into erythrophagocytes, leveraging antioxidative and iron recycling capacities to defend against hemolytic stress. This unique phenotype transformation is coordinated by a regulatory network comprising the transcription factors BACH1, SPI-C, NRF2, and ATF1. Erythrophagocytes negatively regulate inflammation and immunity and may modulate disease-specific outcomes in hemolytic anemia, wound healing, atherosclerosis, and cancer. In this opinion article, we outline the known and presumed functions of erythrophagocytes and their implications for therapeutic innovation and research.

Diagnosis and clinical management of enzymopathies

At least 16 genetically determined conditions qualify as red blood cell enzymopathies. They range in frequency from ultrarare to rare, with the exception of glucose-6-phosphate dehydrogenase deficiency, which is very common. Nearly all these enzymopathies manifest as chronic hemolytic anemias, with an onset often in the neonatal period. The diagnosis can be quite easy, such as when a child presents with dark urine after eating fava beans, or it can be quite difficult, such as when an adult presents with mild anemia and gallstones. In general, 4 steps are recommended: (1) recognizing chronic hemolytic anemia; (2) excluding acquired causes; (3) excluding hemoglobinopathies and membranopathies; (4) pinpointing which red blood cell enzyme is deficient. Step 4 requires 1 or many enzyme assays; alternatively, DNA testing against an appropriate gene panel can combine steps 3 and 4. Most patients with a red blood cell enzymopathy can be managed by good supportive care, including blood transfusion, iron chelation when necessary, and splenectomy in selected cases; however, some patients have serious extraerythrocytic manifestations that are difficult to manage. In the absence of these, red blood cell enzymopathies are in principle amenable to hematopoietic stem cell transplantation and gene therapy/gene editing.

Centrifugation Removes a Population of Large Vesicles, or "Macroparticles," Intermediate in Size to RBCs and Microvesicles

Microparticles or microvesicles (MPs/MVs) are sub-cellular vesicles with a growing number of known biological functions. Microvesicles from a variety of parent cells within the vascular system increase in numerous pathological states. Red blood cell-derived MVs (RMVs) are relatively less studied than other types of circulating MVs despite red blood cells (RBCs) being the most abundant intravascular cell. This may be in part due the echoes of past misconceptions that RBCs were merely floating anucleate bags of hemoglobin rather than dynamic and responsive cells. The initial aim of this study was to maximize the concentration of RMVs derived from various blood or blood products by focusing on the optimal isolation conditions without creating more MVs from artificial manipulation. We found that allowing RBCs to sediment overnight resulted in a continuum in size of RBC membrane-containing fragments or vesicles extending beyond the 1 µm size limit suggested by many as the maximal size of an MV. Additionally, dilution and centrifugation factors were studied that altered the resultant MV population concentration. The heterogeneous size of RMVs was confirmed in mice models of hemolytic anemia. This methodological finding establishes a new paradigm in that it blurs the line between RBC, fragment, and RMV as well as suggests that the concentration of circulating RMVs may be widely underestimated given that centrifugation removes the majority of such RBC-derived membrane-containing particles.

Hematological Manifestations among Patients with Rheumatic Diseases

BACKGROUND

Rheumatic diseases have many hematological manifestations. Blood dyscrasias and other hematological abnormalities are sometimes the first sign of rheumatic disease. In addition, novel antirheumatic biological agents may cause cytopenias.

SUMMARY

The aim of this review was to discuss cytopenias caused by systemic lupus erythematosus and antirheumatic drugs, Felty's syndrome in rheumatoid arthritis, and autoimmune hemolytic anemia, thrombosis, and thrombotic microangiopathies related to rheumatological conditions such as catastrophic antiphospholipid syndrome and scleroderma renal crisis. Key Message: The differential diagnosis of various hematological disorders should include rheumatic autoimmune diseases among other causes of blood cell and hemostasis abnormalities. It is crucial that hematologists be aware of these presentations so that they are diagnosed and treated in a timely manner.

Canonical signaling by TGF family members in mesenchymal stromal cells is dispensable for hematopoietic niche maintenance under basal and stress conditions

Mesenchymal stromal cells are an important component of the bone marrow hematopoietic niche. Prior studies showed that signaling from members of the transforming growth factor (TGF) superfamily in mesenchymal stromal cells is required for normal niche development. Here, we assessed the impact of TGF family signaling on niche maintenance and stress responses by deleting Smad4 in mesenchymal stromal cells at birth, thereby abrogating canonical TGF signaling. No alteration in the number or spatial organization of CXCL12-abundant reticular (CAR) cells, osteoblasts, or adipocytes was observed in Osx-Cre, Smad4^fl/fl mice, and expression of key niche factors was normal. Basal hematopoiesis and stress erythropoiesis responses to acute hemolytic anemia were normal. TGF-β potently inhibits stromal CXCL12 expression in vitro; however, G-CSF induced decreases in bone marrow CXCL12 expression and subsequent hematopoietic stem/progenitor cell mobilization were normal in Osx-Cre, Tgfbr2^fl/fl mice, in which all TGF-β signaling in mesenchymal stromal is lost. Finally, although a prior study showed that TGF-β enhances recovery from myeloablative therapy, hematopoietic recovery following single or multiple doses of 5-flurauracil were normal in Osx-Cre, Tgfbr2^fl/fl mice. Collectively, these data suggest that TGF family member signaling in mesenchymal stromal cells is dispensable for hematopoietic niche maintenance under basal and stress conditions.

Sterile α-motif domain requirement for cellular signaling and survival

Hundreds of sterile α-motif (SAM) domains have predicted structural similarities and are reported to bind proteins, lipids, or RNAs. However, the majority of these domains have not been analyzed functionally. Previously, we demonstrated that a SAM domain-containing protein, SAMD14, promotes SCF/proto-oncogene c-Kit (c-Kit) signaling, erythroid progenitor function, and erythrocyte regeneration. Deletion of a Samd14 enhancer (Samd14-Enh), occupied by GATA2 and SCL/TAL1 transcription factors, reduces SAMD14 expression in bone marrow and spleen and is lethal in a hemolytic anemia mouse model. To rigorously establish whether Samd14-Enh deletion reduces anemia-dependent c-Kit signaling by lowering SAMD14 levels, we developed a genetic rescue assay in murine Samd14-Enh-/- primary erythroid precursor cells. SAMD14 expression at endogenous levels rescued c-Kit signaling. The conserved SAM domain was required for SAMD14 to increase colony-forming activity, c-Kit signaling, and progenitor survival. To elucidate the molecular determinants of SAM domain function in SAMD14, we substituted its SAM domain with distinct SAM domains predicted to be structurally similar. The chimeras were less effective than SAMD14 itself in rescuing signaling, survival, and colony-forming activities. Thus, the SAMD14 SAM domain has attributes that are distinct from other SAM domains and underlie SAMD14 function as a regulator of cellular signaling and erythrocyte regeneration.

Complementopathies and precision medicine

The renaissance of complement diagnostics and therapeutics has introduced precision medicine into a widened field of complement-mediated diseases. In particular, complement-mediated diseases (or complementopathies) with ongoing or published clinical trials of complement inhibitors include paroxysmal nocturnal hemoglobinuria, cold agglutinin disease, hemolytic uremic syndrome, nephropathies, HELLP syndrome, transplant-associated thrombotic microangiopathy, antiphospholipid antibody syndrome, myasthenia gravis, and neuromyelitis optica. Recognizing that this field is rapidly expanding, we aim to provide a state-of-the-art review of (a) current understanding of complement biology for the clinician, (b) novel insights into complement with potential applicability to clinical practice, (c) complement in disease across various disciplines (hematology, nephrology, obstetrics, transplantation, rheumatology, and neurology), and (d) the potential future of precision medicine. Better understanding of complement diagnostics and therapeutics will not only facilitate physicians treating patients in clinical practice but also provide the basis for future research toward precision medicine in this field.

A typical presentation of dengue fever in a G6PD deficient patient: A case report

Dengue is a mosquito-borne viral disease that has rapidly spread in the recent years, particularly in South Asia. While haematologic complications, such as cytopenia and bleeding, may occur in severe dengue infection, reports of haemolytic anaemia in dengue fever are scant. We report a patient who developed haemolytic anaemia following dengue fever. A 45 years old gentleman presented with five-day history of fever and was recently diagnosed with dengue fever. He developed jaundice and started vomiting on the third day of his clinical course. His laboratory investigations revealed deranged liver profile, Coombs negative haemolytic anaemia and G6PD deficiency. He was treated conservatively with fluids and blood transfusions. His liver functions and haemolytic anaemia gradually resolved. This case highlights the importance of recognising dengue fever-induced haemolytic anaemia in a G6PD deficient patient by physicians and pathologists, enabling better diagnosis and improved management of this life-threatening condition.

An integration-free iPSC line (MUSIi008-A) derived from a patient with severe hemolytic anemia carrying compound heterozygote mutations in KLF1 gene for disease modeling

We generated an induced pluripotent stem cell (iPSC) line from peripheral blood mononuclear cells (PBMNCs) isolated from a 1-year old female carrying compound heterozygote for KLF1 mutations (G176RfsX179 and A298P mutations). Non-integrating Sendai viral (SeV) vectors containing KOS, hc-MYC and hKLF4 were used for reprogramming. The established MUSIi008-A cell line contained the same mutations found in the patient, expressed pluripotent markers, differentiated into cells of three embryonic germ layers both in vitro and in vivo, and exhibited normal karyotype. This cell line may provide an alternative renewable source of cells for in vitro disease modeling of severe transfusion-dependent hemolytic anemia.

Hemolytic Anemia: Evaluation and Differential Diagnosis

Hemolytic anemia is defined by the premature destruction of red blood cells, and can be chronic or life-threatening. It should be part of the differential diagnosis for any normocytic or macrocytic anemia. Hemolysis may occur intravascularly, extravascularly in the reticuloendothelial system, or both. Mechanisms include poor deformability leading to trapping and phagocytosis, antibody-mediated destruction through phagocytosis or direct complement activation, fragmentation due to microthrombi or direct mechanical trauma, oxidation, or direct cellular destruction. Patients with hemolysis may present with acute anemia, jaundice, hematuria, dyspnea, fatigue, tachycardia, and possibly hypotension. Laboratory test results that confirm hemolysis include reticulocytosis, as well as increased lactate dehydrogenase, increased unconjugated bilirubin, and decreased haptoglobin levels. The direct antiglobulin test further differentiates immune causes from nonimmune causes. A peripheral blood smear should be performed when hemolysis is present to identify abnormal red blood cell morphologies. Hemolytic diseases are classified into hemoglobinopathies, membranopathies, enzymopathies, immune-mediated anemias, and extrinsic nonimmune causes. Extrinsic nonimmune causes include the thrombotic microangiopathies, direct trauma, infections, systemic diseases, and oxidative insults. Medications can cause hemolytic anemia through several mechanisms. A rapid onset of anemia or significant hyperbilirubinemia in the neonatal period should prompt consideration of a hemolytic anemia.

Report of Two Cases of Microangiopathic Haemolytic Anaemia Associated with Mucinforming Gastric Adenocarcinoma

Two cases of microangiopathic erythroblastic haemolytic anaemia are reported. In both of them mucinous gastric adenocarcinoma and bone marrow metastasis were present. The patients also showed hepatic and splenic haematopoiesis. In one of these cases neoplastic pulmonary microembolisation was demonstrated. The pathogenesis of both erythroblastosis and microangiopathic haemolisis are discussed.

Mycophenolate mofetil for refractory haemolytic anemia in systemic lupus erythematosus

Mycophenolate mofetil (MMF) has been increasingly used in patients with systemic lupus erythematosus (SLE). While most information concentrates on lupus nephritis, its efficacy in nonrenal manifestations of SLE has not been systematically studied. We describe the successful use of MMF in a patient with SLE-related hemolytic anemia that was refractory to cyclophosphamide, pulse methylprednisolone, intravenous immunoglobulin and cyclosporine. The mechanisms of action of MMF are briefly reviewed.

Effect of Heme Oxygenase-1 Deficiency on Glomerular Proteomics

BACKGROUND

The cytoprotective effect of heme oxygenase (HO)-1 in various forms of renal glomerular injury is established. However, little is known on the role of HO-1 in preserving glomerular structural/functional integrity in the absence of injury. The present study addressed this question in HO-1-deficient rats.

METHODS

HO-1-deficient rats were generated using zinc finger nuclease-mediated HO-1 gene (Hmox1) disruption and studied. Glomeruli were isolated from HO-1-deficient (Hmox1-/-) rats and their wild type (WT) littermates for proteomic analysis.

RESULTS

Glomerular lesions were characterized and differentially expressed proteins important for preserving integrity of the glomerular filtration barrier were identified. HO-1-deficient (Hmox1-/-) rats developed albuminuria with decreased glomerular filtration rate. In albuminuric rats, there were lesions resembling focal and segmental glomerulosclerosis (FSGS). Western blot analysis of the integral slit diaphragm proteins, nephrin and podocin revealed a significant decrease in nephrin, with no change in podocin. Proteomic analysis of glomerular protein lysates from Hmox1-/- and WT rats revealed differential expression of proteins previously linked with FSGS pathogenesis. Specifically, α-actinin-4, actin related protein 3, cytokeratins and novel candidates including transgelin-2 and lamins. Bioinformatic analysis predicted the upregulation of pathways implicated in platelet aggregation and fibrin clot formation.

CONCLUSION

HO-1 is a putative regulator of proteins important in preserving glomerular structural stability and integrity, and in minimizing the activity of proinflammatory pathways.

Cancer risk in East Asian patients associated with acquired haemolytic anaemia: a nationwide population-based cohort study

BACKGROUND

This study investigated whether patients with acquired haemolytic anaemia (AHA) would have elevated cancer risk including that for non-haematological solid tumours. We further examined whether the cancer risk would be different between patients with autoimmune type AHA (AIHA) and patients of non-AIHA.

METHODS

Using nationwide population-based insurance claims data of Taiwan we identified a cohort of patients with AHA with no pre-existing cancer, (n = 3902) and a comparison cohort (n = 39020) without AHA, frequency-matched by gender, age, urbanization of residency and diagnosis date. Incidence and Cox method estimated adjusted hazard ratios (aHR) of cancers controlling covariates by the end of 2010 were calculated. Risks between patients with AIHA and non-AIHA were compared. Sensitivity analysis was carried out to measure the risk of cancer between patients with and without AHA by follow-up years.

RESULTS

Patients with AHA had a 90% greater incidence of cancer than controls, with an aHR of 1.78 (95% confidence interval (CI), 1.50-2.12)]. The overall aHRs of cancer for patients with AIHA and non-AIHA were 2.01 (95% CI, 1.56-2.59) and 1.87 (95% CI, 1.53-2.29), respectively, compared with the comparison cohort. The aHRs for lymphatic-haematopoietic malignancy were 19.5 and 9.59 in the AIHA and non-AIHA cohorts, respectively. No hazard of colorectal, lung, liver or breast cancer was significant.

CONCLUSIONS

There is a near 2-fold elevated risk for subsequent cancer in patients with AHA, particularly for lymphatic-haematopoietic malignancy, which is much greater for patients with AIHA than non-AIHA. These findings can help clinicians decide patient-centred personalized long-term management.

Safety assessment of saponins extract in Dolichos falcatus Klein: Subchronic study in Sprague-Dawley rats

ETHNOPHARMACOLOGICAL RELEVANCE

Dolichos falcatus Klein (DF), a Chinese Dai ethnic medicine popularly known as "Tuoyeteng" in Yunnan province of China, has been widely used in China to treat fracture, rheumatoid arthritis and soft tissue injuries for a long time. Our previous study showed that saponins in DF (DFS) ameliorated the gouty arthritis induced by MSU crystals in vivo and in vitro. The present study was carried out to evaluate the no-observed-adverse-effect level (NOAEL) of DFS.

MATERIALS AND METHODS

Sprague-Dawley rats (10/sex/group) were gavaged with DFS at dose level of 0, 50, 100 and 200 mg/kg body weight /day for 90-days.

RESULTS

DFS administration did not result in mortality or show treatment-related changes in clinical signs of toxicity, body weights gain or feed consumption. Similarly, in addition to slightly hemolytic anemia and gastrointestinal tract lesion in males of high-dose treatment group, no toxicologically significant treatment-related changes in hematological, clinical chemistry, urine analysis parameters, organ weights, and macroscopic and microscopic abnormalities were noted during the testing period.

CONCLUSION

The results of subchronic toxicity study support the NOAEL for DFS as 200 mg/kg/d in females and as 100mg/kg/d in males. These results provide an important reference for further DFS-related clinical trials or new drug exploration.

Passenger lymphocyte syndrome in ABO and Rhesus D minor mismatched liver and kidney transplantation: A prospective analysis

The increasing demand for solid organs has necessitated the use of ABO and Rhesus (Rh) D minor mismatched transplants. The passenger lymphocyte syndrome (PLS) occurs when donor lymphocytes produce antibodies that react with host red blood cell (RBC) antigens and result in hemolysis. Our aim was to evaluate prospectively the role of PLS in post transplant anemia and hemolysis in ABO and RhD minor mismatched recipients of liver and kidney grafts and to study the association of PLS with donor lymphocyte microchimerism. We examined 11 liver and 10 kidney recipients at Day +15 for anemia, markers of hemolysis, direct antiglobulin test and eluates, and serum RBC antibodies. Microchimerism was determined in peripheral blood lymphocytes by genotyping of simple sequence length polymorphisms encoding short tandem repeats. Immune hemolytic anemia and anti-recipient RBC antibodies were observed in 2 out of 11 liver (18.2%) and 2 out of 10 kidney (20%) transplants. RBC antibody specificity reflected the donor to recipient transplant, with anti-blood group B antibodies identified in 2 cases of O to B and 1 case of A to AB transplants while anti-D antibodies were detected in 1 case of RhD-negative to RhD-positive transplant. Donor microchimerism was found in only 1 patient. In conclusion, passenger lymphocyte mediated hemolysis is frequent in minor mismatched liver and kidney transplantation. Recognizing PLS as a potential cause of post transplant anemia may allow for early diagnosis and management to decrease the morbidity and mortality in some patients.

A thermolabile aldolase A mutant causes fever-induced recurrent rhabdomyolysis without hemolytic anemia

Aldolase A deficiency has been reported as a rare cause of hemolytic anemia occasionally associated with myopathy. We identified a deleterious homozygous mutation in the ALDOA gene in 3 siblings with episodic rhabdomyolysis without hemolytic anemia. Myoglobinuria was always triggered by febrile illnesses. We show that the underlying mechanism involves an exacerbation of aldolase A deficiency at high temperatures that affected myoblasts but not erythrocytes. The aldolase A deficiency was rescued by arginine supplementation in vitro but not by glycerol, betaine or benzylhydantoin, three other known chaperones, suggesting that arginine-mediated rescue operated by a mechanism other than protein chaperoning. Lipid droplets accumulated in patient myoblasts relative to control and this was increased by cytokines, and reduced by dexamethasone. Our results expand the clinical spectrum of aldolase A deficiency to isolated temperature-dependent rhabdomyolysis, and suggest that thermolability may be tissue specific. We also propose a treatment for this severe disease.

Inborn defects in the antioxidant systems of human red blood cells

Red blood cells (RBCs) contain large amounts of iron and operate in highly oxygenated tissues. As a result, these cells encounter a continuous oxidative stress. Protective mechanisms against oxidation include prevention of formation of reactive oxygen species (ROS), scavenging of various forms of ROS, and repair of oxidized cellular contents. In general, a partial defect in any of these systems can harm RBCs and promote senescence, but is without chronic hemolytic complaints. In this review we summarize the often rare inborn defects that interfere with the various protective mechanisms present in RBCs. NADPH is the main source of reduction equivalents in RBCs, used by most of the protective systems. When NADPH becomes limiting, red cells are prone to being damaged. In many of the severe RBC enzyme deficiencies, a lack of protective enzyme activity is frustrating erythropoiesis or is not restricted to RBCs. Common hereditary RBC disorders, such as thalassemia, sickle-cell trait, and unstable hemoglobins, give rise to increased oxidative stress caused by free heme and iron generated from hemoglobin. The beneficial effect of thalassemia minor, sickle-cell trait, and glucose-6-phosphate dehydrogenase deficiency on survival of malaria infection may well be due to the shared feature of enhanced oxidative stress. This may inhibit parasite growth, enhance uptake of infected RBCs by spleen macrophages, and/or cause less cytoadherence of the infected cells to capillary endothelium.

Circulating contact-pathway-activating microparticles together with factors IXa and XIa induce spontaneous clotting in plasma of hematology and cardiologic patients

Background and Objective

Using an in vitro experimental model of immobilized tissue factor-initiated clot growth in platelet-free plasma (thrombodynamics), we observed formation of activator-independent isolated spontaneous clots (SC) throughout the plasma volume in patients with cardiac infarction, acute leukemia, hemolytic anemia, and some other disorders. The aim of this work was to characterize this phenomenon and to identify the mechanisms of SC formation.

Methods and Results

Tissue factor inhibitor (VIIai) prevented SC in only 2 out of 23 patient plasma samples. Specific inhibitors of factors IXa and XIa were efficient in all 8 cases that we tested. Also, only factors IXa and XIa added to normal donors’ plasma induced SC formations from isolated centers, in a pattern similar to that in patients’ plasma. In contrast, factors VIIa, Va, tissue factor induced uniform plasma clotting. SC disappeared after high-speed centrifugation. However, phospholipid supplementation of centrifuged plasma returned them at least partially in 5 out of 22 patients’ plasmas, indicating some other role of microparticles than providing phospholipid surface. Circulating procoagulant microparticles isolated from plasma directly activated factor XII in buffer and in diluted plasma. Flow cytometry revealed an increase in procoagulant microparticles in patients’ plasmas with SC.

Conclusion

Our data suggest that combination of circulating active factors (specifically, factors IXa and XIa) with circulating procoagulant and contact-pathway-activating microparticles is the predominant mechanism causing spontaneous clotting in patient plasma.

Thrombotic thrombocytopenic purpura: a hematological emergency

Thrombotic thrombocytopenic purpura (TTP) is a rare but severe disease characterized by mechanical hemolytic anemia and consumptive thrombocytopenia leading to disseminated microvascular thrombosis that causes signs and symptoms of organ ischemia and functional damage. TTP is diagnosed by the presence of microangiopathic hemolytic anemia and thrombocytopenia in a patient who frequently presents with central nervous system involvement and, to a lesser extent, renal dysfunction.

CASE REPORT

We present the case of a 23-year-old female with TTP, diagnosed by the presence of the neurological symptoms, microangiopathic hemolytic anemia and severe thrombocytopenia (platelets 4000/μL). During the clinical evolution, the patient presented the hepatic cytolysis syndrome, following disseminated microvascular thrombosis inside the liver, representing an atypical damage. The diagnosis was difficult because it was necessary to make differential diagnosis with other diseases that evolve with microangiopathic hemolytic anemia in a short time to be able to initiate plasmapheresis. Initiation of the plasmapheresis as soon as possible was the goal of our treatment. Following the plasmapheresis combined with administration of corticosteroids was achieved complete resolution of all symptoms.

CONCLUSIONS

TTP is a hematological emergency and diagnostic challenge. The critical determinant of outcome is timely diagnosis and treatment. Once the diagnosis is suspected, life-saving therapeutic plasma exchange therapy is initiated.

More complications occur in macrolide-resistant than in macrolide-sensitive Mycoplasma pneumoniae pneumonia

We sought to understand the situation of macrolide-resistant genotypes of Mycoplasma pneumoniae, and analyze the relationship between macrolide-resistant genotypes and clinical manifestations of Mycoplasma pneumoniae pneumonia (MPP). Full-length sequencing of the 23S rRNA gene of M. pneumoniae was performed in 235 nasopharyngeal aspirates (NPAs) from children with MPP. We also retrospectively compared the clinical characteristics of macrolide-resistant (MR) M. pneumoniae infections and macrolide-sensitive (MS) M. pneumoniae infections. A total of 206 patients had point mutations in the M. pneumoniae 23S rRNA gene, and these patients are referred to as MR patients. The remaining 29 patients without point mutations are referred to as MS patients. Among 206 MR patients, 199 (96.6%) had A2063G mutations, 6 had A2063T mutations, and the remaining patients had an A2064G mutation. Among the clinical manifestations, we found that the median fever durations were 8 days (range, 0 to 42 days) and 6 days (0 to 14 days) (P < 0.01), the median hospitalization durations were 8 days (2 to 45 days) and 6 days (3 to 16 days) (P < 0.01), and the median fever durations after macrolide therapy were 5 days (0 to 42 days) and 3 days (0 to 10 days) (P < 0.01), respectively, in the MR and MS groups. We also found that the incidence of extrapulmonary complications in the MR group was significantly higher than that in the MS group (P < 0.05). Moreover, the radiological findings were more serious in the MR group than in the MS group (P < 0.05). The increasing prevalence of MR M. pneumoniae has become a significant clinical issue in the pediatric patients, which may lead to more extrapulmonary complications and severe clinical features and radiological manifestations.

Calcium in red blood cells-a perilous balance

Ca2+ is a universal signalling molecule involved in regulating cell cycle and fate, metabolism and structural integrity, motility and volume. Like other cells, red blood cells (RBCs) rely on Ca2+ dependent signalling during differentiation from precursor cells. Intracellular Ca2+ levels in the circulating human RBCs take part not only in controlling biophysical properties such as membrane composition, volume and rheological properties, but also physiological parameters such as metabolic activity, redox state and cell clearance. Extremely low basal permeability of the human RBC membrane to Ca2+ and a powerful Ca2+ pump maintains intracellular free Ca2+ levels between 30 and 60 nM, whereas blood plasma Ca2+ is approximately 1.8 mM. Thus, activation of Ca2+ uptake has an impressive impact on multiple processes in the cells rendering Ca2+ a master regulator in RBCs. Malfunction of Ca2+ transporters in human RBCs leads to excessive accumulation of Ca2+ within the cells. This is associated with a number of pathological states including sickle cell disease, thalassemia, phosphofructokinase deficiency and other forms of hereditary anaemia. Continuous progress in unravelling the molecular nature of Ca2+ transport pathways allows harnessing Ca2+ uptake, avoiding premature RBC clearance and thrombotic complications. This review summarizes our current knowledge of Ca2+ signalling in RBCs emphasizing the importance of this inorganic cation in RBC function and survival.

Alterations in bone and erythropoiesis in hemolytic anemia: comparative study in bled, phenylhydrazine-treated and Plasmodium-infected mice

Sustained erythropoiesis and concurrent bone marrow hyperplasia are proposed to be responsible for low bone mass density (BMD) in chronic hemolytic pathologies. As impaired erythropoiesis is also frequent in these conditions, we hypothesized that free heme may alter marrow and bone physiology in these disorders. Bone status and bone marrow erythropoiesis were studied in mice with hemolytic anemia (HA) induced by phenylhydrazine (PHZ) or Plasmodium infection and in bled mice. All treatments resulted in lower hemoglobin concentrations, enhanced erythropoiesis in the spleen and reticulocytosis. The anemia was severe in mice with acute hemolysis, which also had elevated levels of free heme and ROS. No major changes in cellularity and erythroid cell numbers occurred in the bone marrow of bled mice, which generated higher numbers of erythroid blast forming units (BFU-E) in response to erythropoietin. In contrast, low numbers of bone marrow erythroid precursors and BFU-E and low concentrations of bone remodelling markers were measured in mice with HA, which also had blunted osteoclastogenesis, in opposition to its enhancement in bled mice. The alterations in bone metabolism were accompanied by reduced trabecular bone volume, enhanced trabecular spacing and lower trabecular numbers in mice with HA. Taken together our data suggests that hemolysis exerts distinct effects to bleeding in the marrow and bone and may contribute to osteoporosis through a mechanism independent of the erythropoietic stress.

The pleiotropic effects of erythropoietin in infection and inflammation

Erythropoietin (EPO) is a multi-functional cytokine, which exerts erythropoietic effects but also carries anti-apoptotic and immune-modulatory activities upon binding to two distinct receptors which are expressed on erythroid, parenchymal and immune cells, respectively. Whereas EPO ameliorates hemolytic anemia in malaria or trypanosomiasis and improves the course of autoimmune diseases such as inflammatory bowel disease or autoimmune encephalomyelitis, it deleteriously inhibits macrophage functions in Salmonella infection in animal models. Thus, the specific modulation of extra-erythropoietic EPO activity forms an attractive therapeutic target in infection and inflammation.

Apolipoprotein J/Clusterin is a novel structural component of human erythrocytes and a biomarker of cellular stress and senescence

BACKGROUND

Secretory Apolipoprotein J/Clusterin (sCLU) is a ubiquitously expressed chaperone that has been functionally implicated in several pathological conditions of increased oxidative injury, including aging. Nevertheless, the biological role of sCLU in red blood cells (RBCs) remained largely unknown. In the current study we identified sCLU as a component of human RBCs and we undertook a detailed analysis of its cellular topology. Moreover, we studied the erythrocytic membrane sCLU content during organismal aging, in conditions of increased organismal stress and accelerated RBCs senescence, as well as during physiological in vivo cellular senescence.

METHODOLOGY/PRINCIPAL FINDINGS

By using a combination of molecular, biochemical and high resolution microscopical methods we found that sCLU is a novel structural component of RBCs extra- and intracellular plasma membrane and cytosol. We observed that the RBCs membrane-associated sCLU decreases during organismal aging or exposure to acute stress (e.g. smoking), in patients with congenital hemolytic anemia, as well as during RBCs in vivo senescence. In all cases, sCLU reduction paralleled the expression of typical cellular senescence, redox imbalance and erythrophagocytosis markers which are also indicative of the senescence- and oxidative stress-mediated RBCs membrane vesiculation.

CONCLUSIONS/SIGNIFICANCE

We propose that sCLU at the mature RBCs is not a silent remnant of the erythroid precursors, but an active component being functionally implicated in the signalling mechanisms of cellular senescence and oxidative stress-responses in both healthy and diseased organism. The reduced sCLU protein levels in the RBCs membrane following cell exposure to various endogenous or exogenous stressors closely correlates to the levels of cellular senescence and redox imbalance markers, suggesting the usefulness of sCLU as a sensitive biomarker of senescence and cellular stress.

Cardiac remodelling, blood chemistry, haematology and oxygen consumption of Atlantic cod, Gadus morhua L., induced by experimental haemolytic anaemia with phenylhydrazine

Anaemia is a common pathology associated with many infectious and non-infectious diseases. The effects of haemolytic anaemia induced by i.p. injection of phenylhydrazine (PHZ) were studied in Atlantic cod. Phenylhydrazine injection (0.3 mg kg(-1)) in a DMSO and saline vehicle induced a reproducible and stable anaemia reducing haematocrit, (Hct) by 62% over 3 weeks. Controls consisted of fish injected with saline and DMSO/saline vehicle with minimal effects on Hct or whole blood haemoglobin (Hb). Although anaemia resulted in reduced blood lactate and glucose in PHZ injected fish, there were no effects of anaemia on blood, sodium, chloride or potassium. Similarly, there were no changes in the relative proportions of leucocytes in the blood although an increase in the number of immature erythrocytes was observed in the anaemic fish. Anaemic fish showed a 29 and 22% increase in cardiac somatic index (CSI) relative to saline and vehicle controls, respectively, although there were no significant differences in the linear dimensions of the ventricle. Changes in cardiac somatic and ventricular somatic index correlated positively and significantly with Hct but not with whole blood Hb concentration. Anaemic fish had significantly reduced resting routine oxygen consumption compared with vehicle controls but were not able to increase oxygen consumption following a bout of exhaustive exercise. Plasma lactate concentrations increased significantly after exercise to a greater extent in anaemic fish compared with vehicle control fish. Phenylhydrazine is a useful model for studying haemolytic anaemia in Atlantic cod with minimal effects on blood biochemistry and haematology and clearly reduces the aerobic capacity in Atlantic cod.

Mutation in erythroid specific transcription factor KLF1 causes Hereditary Spherocytosis in the Nan hemolytic anemia mouse model

KLF1 regulates definitive erythropoiesis of red blood cells by facilitating transcription through high affinity binding to CACCC elements within its erythroid specific target genes including those encoding erythrocyte membrane skeleton (EMS) proteins. Deficiencies of EMS proteins in humans lead to the hemolytic anemia Hereditary Spherocytosis (HS) which includes a subpopulation with no known genetic defect. Here we report that a mutation, E339D, in the second zinc finger domain of KLF1 is responsible for HS in the mouse model Nan. The causative nature of this mutation was verified with an allelic test cross between Nan/+ and heterozygous Klf1(+/-) knockout mice. Homology modeling predicted Nan KLF1 binds CACCC elements more tightly, suggesting that Nan KLF1 is a competitive inhibitor of wild-type KLF1. This is the first association of a KLF1 mutation with a disease state in adult mammals and also presents the possibility of being another causative gene for HS in humans.

Bone marrow mitogen-stimulated direct antiglobulin test in a case of erythroblastic synartesis

In this article we report a case of erythroblastic synartesis, a rare disease characterized by ineffective erythropoiesis, clusters of erythroblasts due to membrane invaginations, in which an autoimmune pathogenesis is hypothesized. We investigated the presence of anti-erythroblast autoimmunity in bone marrow cultures using a mitogen-stimulated direct antiglobulin test, a method reported to be able to disclose a latent autoimmunity in various diseases. The test revealed the presence of erythroblast-bound IgG, supporting the hypothesis of the autoimmune pathogenesis of erythroblastic synartesis. Supernatants induced the same specific morphological features, i.e erythroblastic clustering and diserythropoietic signs (multiple nuclei, nuclear inclusions, and intercellular bridges) in normal progenitors.

[Transformations of erythrocytes shape and its regulation]

Erythrocytes can occur in many different shapes. Most of them are pathological and can be involved in diseases such a hemolytic anemia's and sickle cell anemia. Only three kinds of red blood cells are no pathological. Echinocytes, stomatocytes and discocytes can occure in blood stream of healthy organism. The echinocyte-dyscocyte-stomatocyte transformation protects red blood cells from lysis caused by echinocytogenic agents (hypertonic saline, basic pH, vanadate, anionic amphiphiles, ATP depletion etc.) or stomatocytogenic agents (hypotonic saline, acidic pH, cationic amphiphiles etc.). Mechanisms of these transformations can be classified in three group: redistribution of bilayer's lipid, modification Donnan's equilibrium and interaction of band 3 protein with different type of external factors.

Alcohol induced burr cell (echinocytic) haemolytic anaemia and haemochromatosis

A 51-year-old man with chronic alcoholic liver disease developed a severe haemolytic anaemia characterized by the presence of circulating burr-shaped cells (echinocytes). Several transfusions of packed red cells were ineffective in raising the haemoglobin concentration, showing that the abnormality was acquired by the transfused cells. Liver biopsies revealed haemochromatosis. Haematological parameters normalized four months after the patient stopped drinking alcohol, but burr cells were still present and erythrocyte life-span was still markedly shortened at one year follow-up. Since serum cholesterol, HDL-cholesterol, and Apo-AI and Apo-B lipoproteins were considerably decreased, the lipid composition of the red cell membrane was studied. Findings showed that echinocytosis occurred with no change in membrane cholesterol content, nor in cholesterol:phospholipid ratio, but with an alteration in the phosphatidylserine and phosphatidylinositol concentrations. While haemochromatosis was most likely the cause of the erythrocyte anomaly, alcohol intake was probably responsible for the acute onset of haemolytic anaemia with effects directly on the erythrocyte membrane as well as mediated by the progressive hepatic injury, with alterations in the plasma and successively in the intramembrane lipid composition.

Pathologic changes in mice induced by subtilase cytotoxin, a potent new Escherichia coli AB5 toxin that targets the endoplasmic reticulum

Subtilase cytotoxin (SubAB) is the prototype of a recently discovered AB(5) cytotoxin family produced by certain strains of Shiga toxigenic Escherichia coli (STEC). The catalytic A subunit is a highly specific subtilase-like serine protease that cleaves the endoplasmic reticulum chaperone BiP. The toxin is lethal for mice, but the pathology it induces is poorly understood. Here, we show that intraperitoneal injection of SubAB causes microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment in mice--characteristics typical of Shiga toxin-induced hemolytic uremic syndrome. SubAB caused extensive microvascular thrombosis and other histologic damage in the brain, kidneys, and liver, as well as dramatic splenic atrophy. Peripheral blood leukocyte levels were increased at 24 h; there was also significant neutrophil infiltration in the liver, kidneys, and spleen and toxin-induced apoptosis at these sites. These findings raise the possibility that SubAB directly contributes to pathology in humans infected with strains of STEC that produce both Shiga toxin and SubAB.

Toxicogenomics of Drug-Induced Hemolytic Anemia by Analyzing Gene Expression Profiles in the Spleen

Hemolytic anemia is a serious adverse effect of therapeutic drugs that is caused by increased destruction of drug-damaged erythrocytes by macrophages in the spleen and liver. We previously applied a toxicogenomic approach to the toxicity by analyzing microarray data of the liver of rats dosed with two hemolytic agents: phenylhydrazine and phenacetin. In the present study, we analyzed gene expression profiles in the spleen, the primary organ for destruction of damaged erythrocytes, of the same models in order to identify splenic gene expression alterations that could be used to predict the hematotoxicity. Microarray analyses revealed hundreds of genes commonly deregulated under all severe hemolytic conditions, which included genes related to splenic events characteristic of the hematotoxicity, such as proteolysis and iron metabolism. Eleven upregulated genes were selected as biomarker candidates, and their expression changes were validated by quantitative real-time PCR. The transcript levels of most of these genes showed strong correlation with the results of classical toxicological assays (e.g., histopathology and hematology). Furthermore, hierarchical clustering analysis suggested that altered expression patterns of the 11 genes sensitively reflected the erythrocyte damage even under a condition that caused no decrease in erythrocyte counts. Among the selected genes, heme oxygenase 1 was one of the most promising biomarker candidates, the upregulation of which on the protein level was confirmed by immunohistochemistry. These results indicate that altered splenic expression of a subset of genes may allow detection of drug-induced hemolytic anemia, with better sensitivity than that of erythrocyte counts in the blood.

Thrombotic thrombocytopenic purpura induced by trimethoprim-sulfamethoxazole in a Jehovah's Witness

We report a case of Thrombotic Thrombocytopenic Purpura occurring as an allergic response to trimethoprim-sulfamethoxazole therapy (Bactrim, Septra) in a Jehovah's Witness patient. The patient presented with fulminant microangiopathic hemolytic anemia and thrombocytopenia within 48 hr of initiating therapy with trimethoprim-sulfamethoxazole. Other symptoms of drug hypersensitivity included nausea, vomiting, urticarial rash, and leukopenia. Because of her religious faith, the patient was supported without plasma therapy with use of intravenous immunoglobulin, steroids, rituximab, and erythropoietin.

Hb Indianapolis [beta112 (G14) Cys-->Arg] as the probable cause of moderate hemolytic anemia and renal damage in a Brazilian patient

Hemoglobin (Hb) Indianapolis [beta112 (G14) Cys-->Arg] is a rare and slightly unstable beta-globin variant. All carriers described to date were clinically normal with only mild reticulocytosis. We report here a case of a Brazilian patient in whom hemolytic anemia and acute renal failure were probably caused by the presence of this variant.

Erythrocyte membrane defects in hemolytic anemias found through derivative thermal analysis of electric impedance

Hereditary hemolytic anemias originate mainly from defects in hemoglobin and plasma membrane proteins. Here, we propose a new method, thermal analysis of impedance, sensitive to membrane defects. It detects three processes in erythrocyte membrane; fall in membrane capacity at 49.5 degrees C and activation of passive PO(4)(2+) permeability at 37 degrees C and inorganic ions at 61.5 degrees C. The denaturation of spectrin is involved in the first process whilst the anion channel is involved in latter processes. Using this method three persons with xerocytosis were found whereby the fall in membrane capacity and spherization of erythrocytes were both postponed (53 degrees C) compared to control (49.5 degrees C). In contrast to control cells, strong activation of passive permeability for Cl(-) at 37 degrees C and sucrose at 61 degrees C were detected that were both eliminated by pre-inhibition of the anion channel with 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS). In addition, erythrocytes from 15 patients with various forms of anemia were studied in intact state and after refreshment. The results were compared with the data of clinical laboratory and osmotic fragility test. The final conclusion is that this method detects membrane defects with altered spectrin and anion channel syndrome (hereditary xerocytosis, spherocytosis, poikilocytosis and pyropoikilocytosis, elliptocytosis and stomatocytosis) and, after refreshment, helps differentiate them from the anemia with hemoglobinopathy.

Enhanced suicidal death of erythrocytes from gene-targeted mice lacking the Cl-/HCO(3)(-) exchanger AE1

Genetic defects of anion exchanger 1 (AE1) may lead to spherocytic erythrocyte morphology, severe hemolytic anemia, and/or cation leak. In normal erythrocytes, osmotic shock, Cl(-) removal, and energy depletion activate Ca(2+)-permeable cation channels with Ca(2+)-induced suicidal erythrocyte death, i.e., surface exposure of phosphatidylserine, cell shrinkage, and membrane blebbing, all features typical for apoptosis of nucleated cells. The present experiments explored whether AE1 deficiency favors suicidal erythrocyte death. Peripheral blood erythrocyte numbers were significantly smaller in gene-targeted mice lacking AE1 (AE1(-/-) mice) than in their wild-type littermates (AE1(+/+) mice) despite increased percentages of reticulocytes (AE1(-/-): 49%, AE1(+/+): 2%), an indicator of enhanced erythropoiesis. Annexin binding, reflecting phosphatidylserine exposure, was significantly larger in AE1(-/-)erythrocytes/reticulocytes ( approximately 10%) than in AE1(+/+) erythrocytes ( approximately 1%). Osmotic shock (addition of 400 mM sucrose), Cl(-) removal (replacement with gluconate), or energy depletion (removal of glucose) led to significantly stronger annexin binding in AE1(-/-) erythrocytes/reticulocytes than in AE1(+/+) erythrocytes. The increase of annexin binding following exposure to the Ca(2+) ionophore ionomycin (1 muM) was, however, similar in AE1(-/-) and in AE1(+/+) erythrocytes. Fluo3 fluorescence revealed markedly increased cytosolic Ca(2+) permeability in AE1(-/-) erythrocytes/reticulocytes. Clearance of carboxyfluorescein diacetate succinimidyl ester-labeled erythrocytes/reticulocytes from circulating blood was more rapid in AE1(-/-) mice than in AE1(+/+) mice and was accelerated by ionomycin treatment in both genotypes. In conclusion, lack of AE1 is associated with enhanced Ca(2+) entry and subsequent scrambling of cell membrane phospholipids.

Infectious haemolytic anaemia causes jaundice outbreaks in seawater-cultured coho salmon, Oncorhynchus kisutch (Walbaum), in Chile

In the last 9 years, epizootics of an icterus condition has affected coho salmon, Oncorhynchus kisutch (Walbaum), reared in seawater cages in southern regions of Chile. At necropsy, fish from field cases exhibited signs of jaundice accompanied by pale light-brown livers and dark spleens. Histopathological and haematological results indicated that these fish presented haemolytic anaemia. After microbiological examination no bacterial or viral agents could be identified as aetiological agents of this disease. In an infectivity trial, coho salmon, Atlantic salmon, Salmo salar L., and rainbow trout, Oncorhynchus mykiss (Walbaum), were inoculated intraperitoneally with a filtrate of an organ homogenate (0.45 microm) from a diseased coho salmon and held for 60 days in tanks supplied with fresh water. The disease was only reproduced in coho salmon in which mortalities, beginning at day 23 post-inoculation (p.i.), reached a cumulative value of 24% at day 27 p.i. This condition was transmitted to non-inoculated cohabiting coho salmon suggesting that it is a waterborne disease. Thus, this icteric condition is caused by an infectious form of haemolytic anaemia, probably of viral aetiology, and coho salmon are more susceptible than either Atlantic salmon or rainbow trout.

Circulating Endothelial Cells as a Prognostic Marker in Thrombotic Microangiopathy

BACKGROUND

Circulating endothelial cells (CECs) are a reliable marker of disease activity in a variety of vascular disorders. Damage to microvascular endothelial cells is a hallmark of thrombotic microangiopathy (TMA). The aim of this study is to identify and count CECs during the course of TMA and evaluate whether cell numbers may serve as a prognostic marker in patients undergoing plasma exchange.

METHODS

Fifteen patients (8 women, 7 men) aged 31 to 66 years with TMA of different causes were studied before and after 4 sessions of plasma exchange. CECs were isolated by using anti-CD146-driven immunomagnetic isolation and counted after staining with Ulex Europaeus lectin-1.

RESULTS

Numbers of CECs were markedly elevated in all patients before treatment (64 to 672 CEC/mL; mean, 320 +/- 205 CEC/mL) compared with healthy controls (0 to 16 CEC/mL; mean, 6.4 +/- 4.2 CEC/mL; P < 0.001). Patients with a favorable outcome had significantly greater initial CEC levels (mean, 426 +/- 175 CEC/mL; P < 0.001), and cell numbers decreased significantly after 4 treatments of plasma exchange (mean, 101 +/- 53 CEC/mL; P = 0.001). Patients with disease unresponsive to plasma exchange presented with lower initial CEC levels (mean, 108 +/- 36 CEC/mL), and numbers failed to decrease after plasma exchange (mean, 114 +/- 57 CEC/mL; P = 0.827).

CONCLUSION

Markedly elevated numbers of CECs reflect severe and widespread endothelial damage in patients with TMA. Cell numbers at presentation and their degree of decrease after 4 sessions of plasma exchange could provide important prognostic clues.

Adult murine hematopoiesis can proceed without β1 and β7 integrins

The function of α4β1 and α4β7 integrins in hematopoiesis is controversial. While some experimental evidence suggests a crucial role for these integrins in retention and expansion of progenitor cells and lymphopoiesis, others report a less important role in hematopoiesis. Using mice with a deletion of the β1 and the β7 integrin genes restricted to the hematopoietic system we show here that α4β1 and α4β7 integrins are not essential for differentiation of lymphocytes or myelocytes. However, β1β7 mutant mice displayed a transient increase of colony-forming unit (CFU-C) progenitors in the bone marrow and, after phenylhydrazine-induced anemia, a decreased number of splenic erythroid colony-forming units in culture (CFUe's). Array gene expression analysis of CD4+CD8+ double-positive (DP) and CD4–CD8– double-negative (DN) thymocytes and CD19+ and CD4+ splenocytes did not provide any evidence for a compensatory mechanism explaining the mild phenotype. These data show that α4β1 and α4β7 are not required for blood cell differentiation, although in their absence alterations in numbers and distribution of progenitor cells were observed.

Essential mixed cryoglobulinemia type II

We report a rare case of essential mixed cryoglobulinemia type II with membrano-proliferative glomerulonephritis (MPGN) type I in which HCV was not found. Long-term history of palindromic rheumatism, skin leukocytoclastic vasculitis attacks and micro-normocytic anemia preceded the appearance of cryoglobulinemia. Cryoprecipitate consisted of monoclonal IgMk-RF and polyclonal IgG (essential mixed type II). The newly appreciated cryoglobulinemia was associated with Coombs positive hemolytic anemia. The MPGN in this case had a benign course and responded to complex simple therapies including prevention of exposure to cold, low antigen content diet, treatment of provoking factors such as UTI, and maximal dose of ACE inhibitor. Responsiveness of skin vasculitis to colchicine therapy was restored after a two-month colchicine withdrawal period and therefore corticosteroid and immunosuppressive therapy was postponed.

Evaluation of dysmyelopoiesis in cats: 34 cases (1996–2005)

OBJECTIVE

To further classify dysmyelopoiesis as diagnosed by use of a general classification scheme and to determine clinical features and laboratory test results that could be used to differentiate between the various forms of dysmyelopoiesis in cats.

DESIGN

Retrospective case series. Sample Population-Bone marrow slides from 34 cats.

PROCEDURES

Medical records of cats in which dysmyelopoiesis was diagnosed on the basis of blood and bone marrow analyses from 1996 to 2005 were reviewed. Criteria for inclusion in the study were findings of > 10% dysplastic cells in 1 or more hematologic cell lines in the bone marrow and concurrent cytopenias in the blood. Cats that met these criteria were classified into subcategories of myelodysplastic syndromes or secondary dysmyelopoiesis on the basis of reevaluation of slides.

RESULTS

Of 189 bone marrow slides reviewed, 34 (14.9%) had > 10% dysplastic cells in 1 or more cell lines. Cats were subcategorized as having myelodysplastic syndrome with excessive numbers of blast cells (n = 13), myelodysplastic syndrome with refractory cytopenias (8), a variant form of myelodysplastic syndrome (1), and secondary dysmyelopoiesis (12). Findings of dysmyelopoiesis and autoagglutination in cats with myelodysplastic syndrome and in those with immune-mediated anemia complicated differentiating between the 2 conditions.

CONCLUSIONS AND CLINICAL RELEVANCE

Differentiating cats with myelodysplastic syndromes from cats with immune-mediated hemolytic anemia was difficult because severe anemia and autoagglutination may be concurrent findings in both conditions. Differentiating between myelodysplastic syndrome with excessive numbers of blast cells and myelodysplastic syndrome with refractory cytopenias was useful in predicting clinical outcome.

Studies on the biomechanical properties of maturing reticulocytes

We investigated the biomechanical properties of reticulocytes obtained from an animal model of hemolytic anemia induced by antibody injection. The hemorheological indices, membrane viscoelasticity, membrane fluidity, and the secondary structure of membrane proteins of the reticulocytes were monitored continuously during the course of their maturation into erythrocytes. The results indicate that reticulocytes had lower deformability, lower membrane fluidity, greater viscoelastic modulus and lesser proportions of alpha-helices and beta-sheets in protein secondary structures than mature erythrocytes. All these indices approached to the level of normal erythrocytes when reticulocytes transformed during maturation. The results help to enhance our understanding of the biomechanical properties of the reticulocytes in their maturing process with clinical diagnosis significances.

Identification of two new members, XPLAC and XTES, of the XK family

XK, a putative membrane transporter, is a component of the XK/Kell complex of the Kell blood group system. XK's substrate is unknown but absence of the protein, as occurs in the McLeod phenotype, is associated with red cell acanthocytosis and late onset central nervous system and neuromuscular abnormalities known as the McLeod syndrome. We have cloned two cDNAs, XPLAC (GenBank accession no. AY589511) and XTES (GenBank accession no. AY989815), which are closely related to XK and define them together as the XK family. XPLAC has a 2.9 kb cDNA that encodes 462 amino acids and XTES has a 1.6 kb cDNA coding 459 amino acids. The predicted molecular weights are 53.6 kDa for XPLAC and 53.4 kDa for XTES, which are similar to that of XK, which is 50.9 kDa. Unlike XK which is ubiquitously expressed XPLAC is expressed mostly in placenta and adrenal gland while XTES is exclusively expressed in primate testis. XPLAC has 37% and XTES has 31% amino acid identity with XK protein and they are predicted to have a similar topology to XK. XPLAC, like XK, has 3 exons and is located on X chromosome at q22.1, while XTES has 4 exons and is located at 22q11.1. Phylogenetic analysis shows that there are at least 5 additional vertebrate genes that are evolutionarily distantly related to the XK family. A domain with consensus sequences (ced-8 domain) for the extended family is described.