An unusual case of CD4+ CD7+ CD56+ acute leukemia with overlapping features of type 2 dendritic cell (DC2) and myeloid/NK cell precursor acute leukemia.

Type 2 dendritic cell (DC2) acute leukemia has been recently described. We report here an unusual case of a 17-yr-old adolescent with overlapping features of DC2 and myeloid/NK cell precursor acute leukemia as defined by Suzuki et al. The patient presented with lymphadenopathy and hepatosplenomegaly without extranodal manifestations in skin or elsewhere. The morphologic, cytochemical and immunophenotypic features were compatible with those described in DC2 acute leukemia, with co-expression of CD4, CD56 and CD123 antigens. The novel markers BDCA-4 and BDCA-2 considered specific for DC2s were co-expressed. However, bright CD7 positivity along with a dim expression of CD33 (57%) and CD117 (27%) were also noted. Additionally, there was bright expression of NG2 monoclonal antibody 7.1, a frequent finding in myeloid/NK cell precursor acute leukemia. The interpretation of the immunophenotypic profile leads to the hypothesis on the existence of borderline cases between DC2 and myeloid/NK cell precursor acute leukemia. Still, other hypotheses can not be overlooked, such as the possibility for a kind of variant monoblastic leukemia or of another rare entity of acute unclassified leukemia.

Triethylene glycol poisoning treated with intravenous ethanol infusion.

INTRODUCTION: Poisoning with triethylene glycol has been rarely reported in humans. Triethylene glycol is thought to be metabolized by alcohol dehydrogenase to acidic products resulting in the production of a metabolic acidemia. Triethylene glycol metabolism has previously been shown to be inhibited by fomepizole (4-methyl pyrazole) administration. We report a case of triethylene glycol ingestion, presenting with a metabolic acidemia, treated with intravenous ethanol administration. CASE REPORT: A 23-year-old female presented to the emergency department approximately 1-1.5 hours following ingestion of a gulp of triethylene glycol (99%) brake fluid with coma (GCS-3) and metabolic acidemia (pH 7.03, PCO2 44 mm Hg, Bicarbonate 11 mmol/L, anion gap 30 mmol/L, serum creatinine 90 mumol/L). She was intubated and given 100 mmol of intravenous sodium bicarbonate. An ethanol loading dose was administered followed by an infusion to maintain serum ethanol at 100 mg/dL. Acidemia gradually resolved over the next 8 hours and she was extubated 12 hours later. The ethanol infusion was continued for a total of 22 hours. There was no recurrence of acidemia. Serum ethanol, ethylene glycol, and methanol levels were nondetectable on presentation, as was serum salicylate. Urine drug of abuse screen and thin-layer chromatography revealed no other coingested substances. The patient was discharged to a psychiatric ward 36 hours postingestion. CONCLUSION: Pure triethylene glycol poisoning results in coma and metabolic acidemia and may be treated with alcohol dehydrogenase inhibitors such as ethanol.

Targeted inactivation of murine band 3 (AE1) gene produces a hypercoagulable state causing widespread thrombosis in vivo.

Only 5% to 10% of band 3 null mice survive the neonatal period. To determine the cause of death, 3 adult and 11 newborn band 3 null mice were submitted for histopathologic examination. All but 1 pup showed evidence of thrombosis including: (1) large thrombotic lesions in the heart, which were partially organized, calcified in some fields, and endothelialized, indicating a process that developed premortem (3 of 3 adults and 6 of 11 pups). (2) Subcapsular necrotic areas in the liver suggestive of premortem ischemic events caused by arteriolar occlusions (8 of 11 pups). (3) Large vein thrombi (4 of 11 pups). To investigate the etiology of this hypercoagulable state, we have used the Russell's viper venom test (RVV) to show that red blood cells (RBCs) from band 3 null mice significantly shorten the RVV clotting time of normal plasma in a dose-dependent fashion, whereas RBCs from normal mice have no effect, suggesting that the membrane of band 3 null RBCs provides a suitable surface for activation of the prothrombinase complex. Using flow cytometry, we have examined the phosphatidylserine (PS)-specific binding of fluorescein isothiocyanate (FITC)-annexin V to normal and band 3 null RBCs. A subpopulation of cells (3% to 5% of RBCs) with increased FITC-annexin V binding was detected in band 3 null RBCs as compared with normal RBCs. Furthermore, the entire cell population of band 3 null RBCs shows a measurable increase in the mean fluorescence intensity, suggesting that band 3 null RBCs may have increased PS exposure on the outer membrane leaflet. These findings are further supported by direct fluorescence microscopy of normal and band 3 null RBCs labeled with FITC-annexin V. Based on these observations, we postulate that the high mortality of band 3 null mice may be related to a hypercoagulable state, which appears to originate from changes in the phospholipid composition of the membrane leading to PS exposure on the outer leaflet.

Characterization of the underlying molecular defect in hereditary spherocytosis associated with spectrin deficiency.

Several subsets of patients with hereditary spherocytosis (HS) have been defined based on the specific red blood cell membrane protein deficiencies involving spectrin, ankyrin, band 3, and protein 4.2. Mutations of the genes encoding these proteins are currently being uncovered. Regarding spectrin, only three isolated cases of beta-spectrin gene mutations were recently reported in association with HS and spectrin deficiency. We have screened the coding region of the beta-spectrin gene using the SSCP technique, in 40 families with HS associated with spectrin deficiency or combined spectrin and ankyrin deficiencies. In this report we describe six frameshift and nonsense mutations and four missense mutations of the beta-spectrin gene in 11 unrelated families. Taking advantage of modifications in the restriction enzyme recognition sequences introduced by the mutations, we show, in all cases of frameshift and nonsense mutations, the loss of heterozygosity at the cDNA level when compared to genomic DNA, reflecting the absence of the mutant mRNA transcripts. In one family with a large pedigree including six generations and 112 members, we firmly establish the autosomal dominant inheritance of one of the beta-spectrin null mutations. Most of the mutations described are responsible for a phenotype of mild to moderate autosomal dominant form of HS associated with a conspicuous spherocytosis with frequent spiculated cells (8% to 15% acanthocytes). One missense mutation appears to be associated with a recessive form of the disease. Five common restriction enzyme polymorphisms of the coding region of the beta-spectrin gene are also described. Overall, these findings underscore the importance of the beta-spectrin gene mutations in the pathogenesis of HS and reemphasizes the extreme heterogeneity of the underlying molecular basis of this condition.

Hereditary spherocytosis with spectrin deficiency due to an unstable truncated beta spectrin.

Red cell membrane protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and direct quantitation by radioimmunoassay or cytofluorometry defines four distinct subsets of patients with hereditary spherocytosis: Patients with isolated spectrin deficiency, combined spectrin and ankyrin deficiency, band 3 deficiency, and protein 4.2 deficiency. In regard to the first group, only one mutation of beta spectrin has been reported in the literature. We describe a spectrin variant characterized by a truncated beta chain, and associated with hereditary spherocytosis and isolated spectrin deficiency. The clinical phenotype consists of a moderate hemolytic anemia with spherocytosis and frequent spiculation of the red cells. We present the biochemical characteristics of this mutant protein and show that it constitutes only 12% of the total spectrin on the membrane. We show that the truncation of the protein is the result of a single point mutation at position +1 (G-->A) of the donor consensus splice site of intron 17 leading to an aberrant beta spectrin transcriptional message lacking exons 16 and 17. To elucidate the basis for the decreased amount of the truncated protein on the membrane and the overall spectrin deficiency, we provide evidence that the mutated gene is transcribed but its mRNA is less abundant than its normal counterpart in reticulocytes; we also show that the mutant protein is synthesized in decreased amounts in the cytoplasm of erythroid progenitor cells, and appears to be susceptible to proteolytic degradation. This mutant spectrin underscores the importance of the regulatory role played by the beta spectrin molecule in the assembly of alphabeta spectrin heterodimers on the membrane.

Molecular basis of spectrin deficiency in beta spectrin Durham. A deletion within beta spectrin adjacent to the ankyrin-binding site precludes spectrin attachment to the membrane in hereditary spherocytosis.

We describe a spectrin variant characterized by a truncated beta chain and associated with hereditary spherocytosis. The clinical phenotype consists of a moderate hemolytic anemia with striking spherocytosis and mild spiculation of the red cells. We describe the biochemical characteristics of this truncated protein which constitutes only 10% of the total beta spectrin present on the membrane, resulting in spectrin deficiency. Analysis of reticulocyte cDNA revealed the deletion of exons 22 and 23. We show, using Southern blot analysis, that this truncation results from a 4.6-kb genomic deletion. To elucidate the basis for the decreased amount of the truncated protein on the membrane and the overall spectrin deficiency, we show that (a) the mutated gene is efficiently transcribed and its mRNA abundant in reticulocytes, (b) the mutant protein is normally synthesized in erythroid progenitor cells, (c) the stability of the mutant protein in the cytoplasm of erythroblasts parallels that of the normal beta spectrin, and (d) the abnormal protein is inefficiently incorporated into the membrane of erythroblasts. We conclude that the truncation within the beta spectrin leads to inefficient incorporation of the mutant protein into the skeleton despite its normal synthesis and stability. We postulate that this misincorporation results from conformational changes of the beta spectrin subunit affecting the binding of the abnormal heterodimer to ankyrin, and we provide evidence based on binding assays of recombinant synthetic peptides to inside-out-vesicles to support this model.

A novel mobile element inserted in the alpha spectrin gene: spectrin dayton. A truncated alpha spectrin associated with hereditary elliptocytosis.

Nonviral retrotransposons, retropseudogenes, and short interspersed nuclear elements (SINEs) are mobile DNA segments capable of transposition to new genomic locations, where they may alter gene expression. De novo integration into specific genes has been described in both germ and somatic cells. We report a family with hereditary elliptocytosis and pyropoikilocytosis associated with a truncated alpha-spectrin protein. We present the biochemical characteristics of this abnormal protein and show that the alpha-spectrin gene is disrupted by a mobile element resulting in exon skipping. This element causes duplication of the insertion site and is terminated by a long poly-A tail downstream of multiple consensus polyadenylation signals. Southern blot analysis of human genomic DNA, using this element as probe, reveals one to three copies per individual. This element has no homology to any previously reported sequence and therefore appears to be a member of a novel family of mobile elements.

Rupture of the pericardium presenting as postpericardial trauma syndrome late after blunt chest injury.

A 40-year-old man presented with a clinical picture of postpericardial trauma syndrome six weeks after blunt injury to the chest. Posttraumatic pericardial rupture was diagnosed at exploratory thoracotomy. The presence of aortic regurgitation due to a previously undiagnosed congenital sinus of Valsalva aneurysm complicated the clinical picture. To our knowledge this is the first report of postpericardial trauma syndrome associated with pericardial rupture after blunt chest injury. It emphasizes the high index of suspicion required for diagnosis of pericardial rupture, a condition with potentially lethal complications.

On the explanation of the M-mode echocardiographic image of an atrial myxoma.

Two experimental models were used to simulate the motion of a valve leaflet and atrial myxoma in order to investigate the echocardiographic images produced. Both support the view that an endogenous contrast effect, i.e. surfaces of different acoustic densities that are produced as a result of turbulence in a fluid medium and give rise to echo images, contributes to the echocardiographic M-mode appearance of the atrial mass.