Desferrioxamine (DFO) conjugated with starch decreases NAD redox potential of intact red blood cells (RBC): evidence for DFO as an extracellular inducer of oxidant stress in RBC

Desferrioxamine (DFO) is an important iron-chelating agent. It has also been thought of as an agent with anti-oxidant potential as it chelates ferric iron in various parts of the body. However, there is evidence suggesting that it may paradoxically affect red blood cells (RBCs) by inducing intracellular oxidant stress. Recently we observed that incubation of RBCs with DFO decreases NAD redox potential in normal RBC. To further understand the mechanism of DFO's interaction with RBC, we conducted a study to determine the effect of extracellular DFO upon RBC's redox status. We examined NAD redox potential in intact RBC (N = 7) incubated with DFO conjugated to starch. RBCs were incubated with 4 mM DFO for 3(1/2) hr and with 6 mM DFO for 2 and 3(1/2) hr. Significant decreases in NAD redox potential were observed after the incubations. With 4 mM DFO at the 3 (1/2) hr time point the mean decrease was 12.37% +/- 9.96% (P < 0.0085). With 6 mM DFO, the mean decreases were 18.54% +/- 9.79% (P < 0.0013) and 19.16% +/- 8.78% (P < 0.0006) for the 2 and 3 (1/2) hr incubations, respectively. DFO by itself is very poorly permeable to RBC. Conjugation with starch further ensured impermeability of DFO. The data presented here confirm the oxidant effect of DFO on RBC. The data also demonstrate that the effect of DFO on RBC's NAD redox potential originates extracellularly.

Deferiprone, an oral iron chelator, ameliorates experimental colitis and gastric ulceration in rats

Iron is pivotal is producing tissue-damaging reactive oxygen metabolites. Our aim is to determine the antiinflammatory activity of deferiprone, an oral iron chelator, in experimental colitis and gastritis. Colitis was induced by intraceccal administration of 2 ml 5% acetic acid or by intracolonic administration of 0.1 ml 3% iodoacetamide, with or without cotreatment with deferiprone. Gastritis was induced by intragastric administration of ethanol or hydrochloric acid (HCl) and by subcutaneous injection of indomethacin, with and without deferiprone. Rats were killed 24 hours after acetic acid and iodoacetamide, 30 minutes after ethanol, one hour after HCl, and three hours after indomethacin administration. The colon or stomach was isolated, macroscopic damage was measured, and mucosal samples were obtained for determination of eicosanoid generation, myeloperoxidase (MPO), and nitric oxide synthase (NOS) activities. Deferiprone decreased iodoacetamide and acetic acid-induced macroscopic colonic damage by 67% and 69%, respectively, and macroscopic gastric damage by 91%, 68%, and 46% induced by ethanol, HCl, and indomethacin, respectively. The effect of deferiprone was accompanied by significant decrease in colonic and gastric, MPO and NOS activities, and colonic prostaglandin E2 (PGE2) generation, in acetic acid, ethanol, and indomethacin models, whereas in the iodoacetamide and HCl models attenuation of the decrease in PGE2 generation was seen. Deferiprone is protective in experimental colitis and gastritis, probably due to decreased production of iron-dependent oxygen-free radicals. Oral iron chelators may constitute a novel approach to ameliorate gastrointestinal inflammatory disorders.

Transport of 14C-deferiprone in normal, thalassaemic and sickle red blood cells

The transport of deferiprone (L1) in normal (N), sickle (S) and thalassaemic (T) red blood cells (RBC) was determined by incubation with 14C-L1 at 37 degrees C. Following incubation with 0.5 mM 14C-L1 for 4 h, the intracellular concentration of L1 in T RBC was 3 times higher than was found extracellularly. In contrast, no concentration gradient across N and S RBC membranes was detected. Efflux studies showed that T RBC released only 17 +/- 2% of 14C-L1 into the extracellular space. We hypothesize that L1 accumulation in T RBC results from their high content of chelatable iron and formation of large, hydrophilic L1-Fe(III) complexes trapped within the cytosol.

Deferiprone therapy in homozygous human beta-thalassemia removes erythrocyte membrane free iron and reduces KCl cotransport activity

Deposition of free iron is a characteristic feature of beta-thalassemia (beta-thal) red blood cells believed to play an important role in the generation of oxidative injury to the cell membrane. Increased red blood cell KCI cotransport, reduced K content, and cell dehydration are also found in beta-thal red blood cells. It is not known, however, whether deposition of free iron plays a role in these membrane transport changes. To explore this issue, we studied-both in vitro and in vivo-the effect on KCI cotransport of removing red blood cell membrane free iron from beta-thal erythrocytes. Eleven patients with beta-thal major who underwent long-term transfusion and were treated with deferiprone (75 mg/kg/day) for 9 months participated in the study. Deferiprone therapy removed membrane free iron from beta-thal erythrocytes, which was followed by reduced KCI cotransport activity. The reduced KCI cotransport activity was accompanied by an increase in the red blood cell K content. These data suggest that the increased activity of KCI cotransport in beta-thal red blood cells is mediated by the deposition of membrane free iron, a mechanism that may be attenuated by deferiprone therapy.

The molecular pathobiology of cell membrane iron: the sickle red cell as a model

The molecular pathobiology of membrane-associated iron is clearly illustrated by the sickle red blood cell. The cytosolic aspect of the membranes of these cells carries several discrete iron compartments, including denatured hemoglobin and free heme, as well as molecular iron associated with membrane aminophospholipid and denatured globin. Affinity of the membrane for molecular iron is extraordinarily high and predicted to keep cytosolic free iron concentration < 10(-20) M. Membrane iron is bioactive and able to valence cycle, thus serving as a catalyst for generation of highly reactive hydroxyl radical. As a consequence of this oxidative biochemistry at the cytosol/membrane interface, multiple membrane defects arise that are of pathophysiologic importance. Thus, sickle red cells provide a pathobiologic paradigm for the membrane-damaging effect of iron-mediated targeting of oxidative damage at a sub-cellular level. This is relevant to a variety of biologic conditions accompanied by decompartmentalization of iron.

Removal of erythrocyte membrane iron in vivo ameliorates the pathobiology of murine thalassemia

Abnormal deposits of free iron are found on the cytoplasmic surface of red blood cell (RBC) membranes in beta-thalassemia. To test the hypothesis that this is of importance to RBC pathobiology, we administered the iron chelator deferiprone (L1) intraperitoneally to beta-thalassemic mice for 4 wk and then studied RBC survival and membrane characteristics. L1 therapy decreased membrane free iron by 50% (P = 0.04) and concomitantly improved oxidation of membrane proteins (P = 0.007), the proportion of RBC gilded with immunoglobulin (P = 0.001), RBC potassium content (P < 0.001), and mean corpuscular volume (P < 0.001). Osmotic gradient ektacytometry confirmed a trend toward improvement of RBC hydration status. As determined by clearance of RBC biotinylated in vivo, RBC survival also was significantly improved in L1-treated mice compared with controls (P = 0.007). Thus, in vivo therapy with L1 removes pathologic free iron deposits from RBC membranes in murine thalassemia, and causes improvement in membrane function and RBC survival. This result provides in vivo confirmation that abnormal membrane free iron deposits contribute to the pathobiology of thalassemic RBC.

Isolated beta-globin chains reproduce, in normal red cell membranes, the defective binding of spectrin to alpha-thalassaemic membranes

Alpha-thalassaemic erythrocytes develop a specific membrane skeletal defect that is manifest as a loss of normal spectrin-binding sites on the inner surface of the thalassaemic membranes. To test whether this lesion could be caused by the excess free beta-globin chains that accumulate in alpha-thalassaemic red cells, we incubated normal red cell membranes with native, haem-containing alpha or beta globin chains or with haemoglobin A. Spectrin-depleted inside-out membrane vesicles (IOVs) derived from membranes incubated with beta-globin chains bound only 9 +/- 3% as much spectrin as IOVs from control membranes incubated with bovine serum albumin. In contrast. IOVs from membranes incubated with alpha-globin chains or haemoglobin A were nearly normal (79 +/- 3% and 86 +/- 5% of controls, respectively). This differential effect of globin chains was not seen when membranes were first transformed into spectrin-depleted IOVs and then incubated with the isolated globin chains. Under these conditions, both alpha and beta globin chains reduced the spectrin-binding capacity of the IOVs by approximately 45% (alpha 46 +/- 7%, beta 43 +/- 6%) whereas haemoglobin A had no effect. Unlike IOVs, spectrin isolated from membranes exposed to alpha or beta globin chains bound normally to IOVs and to actin (in the presence of protein 4.1). These studies show that isolated beta-globin chains (but not alpha-globin chains) can produce a spectrin-binding defect in normal red cell membranes similar to that seen in alpha thalassaemia. The existence of similar defects in the membrane skeletons of red cells from other diseases with unstable beta globins suggests a common pathophysiology for the premature destruction of these cells.

Extremely high avidity association of Fe(III) with the sickle red cell membrane

Red blood cells (RBCs) from patients with sickle cell anemia and thalassemia carry abnormal accumulations of molecular Fe(III) at the cytosol/membrane interface. The avidity of the red cell membrane for this iron has not been defined. Using open ghost membranes prepared from sickle RBC, we examined the ability of membrane-associated Fe(III) to resist removal by 15 chelators representing a 40-log range of affinities for Fe(III). Efficacy of chelators was compared with literature values for their idealized affinity for iron as represented by the cummulative stability constant (beta n), their effective stability constant reflecting affinity under biologic conditions (Keff), and an indicator of their ability to chelate Fe(III) in the presence of an insoluble phase of iron (Ksol). Deferoxamine, a very high affinity chelator having log beta n = 30.6, was found to be the lowest affinity chelator able to remove RBC membrane Fe(III). Regardless of chelator beta n, only those agents able to preserve log Keff > or = 12 were able to do so, indicating that the membrane's effective avidity for Fe(III) is on the order of 10(12). Additional confirmation that membrane avidity for Fe(III) is extremely high is found in the observation that only chelators having log Ksol > 0 were effective. Potential physiologic iron chelators in cytoplasm of pathologic red cells are unable to prevent or reverse iron accumulation on the membrane because they do not have sufficiently high affinity for iron. These data argue that RBC membrane Fe(III) is truly pathologic.

Catalysis of soluble hemoglobin oxidation by free iron on sickle red cell membranes

Abnormal deposition of hemichrome on the inner aspect of the sickle red cell membrane promotes premature cell demise. The steps proximate to hemichrome formation in these cells are poorly understood. To test the hypothesis that the pathologic deposits of free ferric iron located on the inner aspect of sickle cell membranes would be redox active and promote oxidation of soluble oxyhemoglobin, we incubated native versus iron-stripped sickle or normal ghost membranes with oxyhemoglobin S. We found that sickle membranes exerted an exaggerated effect on methemoglobin formation in solution, an effect completely accounted for by their abnormal content of free iron. This ability of sickle membranes to promote hemoglobin oxidation was not diminished by catalase or by presence of a high-affinity, iron-inactivating chelator that is unable to remove membrane iron. Examination of those membranes likewise revealed that their free iron content promoted deposition of additional heme-protein. These results establish that the potential redox couple formed by membrane-associated ferric iron and cytoplasmic oxyhemoglobin is promotive of hemoglobin oxidation and deposition of hemichrome on the membrane. This predicts that removal of pathologic membrane iron might help prevent the detrimental formation of methemoglobin and hemichrome in vivo, insofar as this is accelerated by transition metal.

Deferiprone (L1) chelates pathologic iron deposits from membranes of intact thalassemic and sickle red blood cells both in vitro and in vivo

Red blood cell (RBC) membranes from patients with the thalassemic and sickle hemoglobinopathies carry abnormal deposits of iron presumed to mediate a variety of oxidative-induced membrane dysfunctions. We hypothesized that the oral iron chelator deferiprone (L1), which has an enhanced capacity to permeate cell membranes, might be useful in chelating these pathologic iron deposits from intact RBCs. We tested this hypothesis in vitro by incubating L1 with RBCs from 15 patients with thalassemia intermedia and 6 patients with sickle cell anemia. We found that removal of RBC membrane free iron by L1 increased both as a function of time of incubation and L1 concentration. Thus, increasing the time of incubation of thalassemic RBCs with 0.5 mmol/L L1 from 0.5 to 6 hours, enhanced removal of their membrane free iron from 18% +/- 9% to 96% +/- 4%. Dose-response studies showed that incubating thalassemic RBC for 2 hours with L1 concentrations ranging from 0.125 to 0.5 mmol/L resulted in removal of membrane free iron from 28% +/- 15% to 68% +/- 11%. Parallel studies with sickle RBCs showed a similar pattern in time and dose responses. Deferoxamine (DFO), on the other hand, was ineffective in chelating membrane free iron from either thalassemic or sickle RBCs regardless of dose (maximum, 0.333 mmol/L) or time of incubation (maximum, 24 hours). In vivo efficacy of L1 was shown in six thalassemic patients whose RBC membrane free iron decreased by 50% +/- 29% following a 2-week course of L1 at a daily dose of 25 mg/kg. As the dose of L1 was increased to 50 mg/kg/d (n = 5), and then to 75 mg/kg/d (n = 4), 67% +/- 14% and 79% +/- 11%, respectively, of their RBC membrane free iron was removed. L1 therapy--both in vitro and in vivo--also significantly attenuated the malondialdehyde response of thalassemic RBC membranes to in vitro stimulation with peroxide. Remarkably, the heme content of RBC membranes from L1-treated thalassemic patients decreased by 28% +/- 10% during the 3-month study period. These results indicate that L1 can remove pathologic deposits of chelatable iron from thalassemic and sickle RBC membranes, a therapeutic potential not shared by DFO. Furthermore, membrane defects possibly mediated by catalytic iron, such as lipid peroxidation and hemichrome formation, may also be alleviated, at least in part, by L1.

[A national qualifying internal medicine examination for Israeli medical students]

In 1991 the deans of the 4 medical schools in Israel decided to institute a national qualifying examination in internal medicine. This marked the beginning of the process of unifying the qualifying examinations in all major medical fields. We describe the development of the examination, experience with its administration to 720 students in 1992-1994, and the outcome of this initial effort. The examinations were prepared by a committee of senior faculty from the 4 schools, representing all the relevant clinical areas. Professional consultation was provided by the Unit for Medical Education of Tel Aviv University. Each examination consisted of 180 multiple choice items, reflecting an agreed representation of the various medical specialties, and was designed to test both comprehension and problem-solving ability. A syllabus was published by the committee and distributed to students and faculty in preparation for the examination. In composing the examination, the committee took into consideration differences in general policy and varying emphases in the curricula of the 4 schools. Analysis of the results of the 3 annual examinations showed both a high level of reliability and high quality of the majority of the individual test items. There was a trend with time to slightly lower average scores, and fewer passed the exam last year. There was improvement in the results after the first 2 years in the area of problem-solving related to interpretation of imaging, blood smears and clinical photographs, but this trend did not continue into 1994. The introduction of a high level examination based on a common syllabus provided important feedback, improving both student motivation and clinical teaching. For all schools, the outcome of the examination served as an important external indicator of teaching standards. Following this positive experience, uniform examinations in surgical subjects and pediatrics were introduced for the first time in 1993. The committee recommends that Israeli medical schools gradually introduce a comprehensive qualifying examination based on a mutually agreed list of objectives and syllabus.

Clinical relevance of gestational thrombocytopenia of < 100,000/microliters

We identified 22 women with thrombocytopenia of < 100,000/microliters found incidentally during pregnancy and prospectively monitored their platelet count and clinical outcome for a minimum of 6 months postpartum. During the study period, four women became pregnant twice, accounting for a total of 26 pregnancies. The lowest platelet count during pregnancy was 65,600/microliters +/- 19,400 (mean +/- SD), and at delivery 84,500/microliters +/- 32,300 (P < 0.02). The thrombocytopenia was virtually asymptomatic in all patients during the pregnancy and delivery, whether vaginal or surgical. Neonatal platelet counts (n = 18) were normal (270,700/microliters +/- 69,900), and none of the newborns (n = 24) had a bleeding diathesis. Normalization of the platelet count (i.e., > 150,000/microliters) was documented in 18 patients within 1 month postpartum, in five within 3 months postpartum, and in two as late as 5 months after delivery. One woman did not recover from the thrombocytopenia and eventually developed other stigmata of an autoimmune disease. Long-term follow-up showed recurrence of thrombocytopenia in four patients: three in the context of a subsequent pregnancy and one who developed idiopathic thrombocytopenic purpura. Retrospective analysis of blood counts obtained from 12 previous pregnancies demonstrated thrombocytopenia of a similar degree to the index pregnancy. We conclude that gestational thrombocytopenia of < 100,000/microliters is clinically a benign phenomenon that can recur in subsequent pregnancies and is not accompanied by neonatal thrombocytopenia. In some cases, however, pregnancy-associated thrombocytopenia may be a manifestation of an autoimmune disease with its attendant implications for the neonate. Since the differential diagnosis between the two conditions may be difficult to establish when first encountered during pregnancy, a conservative approach emphasizing careful surveillance and guarded reassurance is justified as long as the platelet counts are > 50,000/microliters.

First trimester listeriosis with normal fetal outcome

The case of a pregnant woman who in the 13th week of gestation presented with a non-specific influenza-like illness ultimately proven to be symptomatic of Listeria monocytogenes septicemia, is described. The patient elected to continue the pregnancy and following antibiotic therapy recovered and delivered a normal infant. At 18 months of age the child was healthy with normal psychomotor development. This case underscores the need to consider the possibility of Listeria monocytogenes septicemia at any stage of pregnancy, and suggests that early institution of antibiotic treatment may result in complete recovery of both mother and fetus.

[Glucose phosphate isomerase deficiency with congenital nonspherocytic hemolytic anemia]

Glucose phosphate isomerase (GPI) deficiency is an unusual cause of hereditary nonspherocytic hemolytic anemia described in Israel in 2 families of Arab ancestry. The disease, inherited as an autosomal recessive disorder, manifests itself by symptoms and signs of chronic hemolysis which are often ameliorated by splenectomy. A variety of defective GPI variants, characterized by modified physicochemical and/or kinetic properties of the enzyme have been reported, suggesting extensive polymorphism for this enzyme deficiency. We recently diagnosed GPI deficiency in a 23-year-old Jewish Ashkenazi man. Since the age of 1 year, when a diagnosis of hemolytic anemia of undetermined etiology was made, he has required frequent blood transfusion. Since splenectomy, performed when he was 6 years old, the requirement for blood transfusions diminished drastically, restricted to hemolytic crises following intercurrent febrile illnesses. To the best of our knowledge, this is the first report of GPI deficiency in an Israeli family of Ashkenazi-Russian origin.

Nonrandom association of free iron with membranes of sickle and beta-thalassemic erythrocytes

To further define the nature of abnormal iron deposits on the membranes of pathologic red blood cells, we have used sickle cell anemia (HbSS), HbSC, and beta-thalassemic erythrocytes (RBCs) to prepare inside-out membranes (IOM) and insoluble membrane aggregates (AGGs) containing coclustered hemichrome and band 3. Study of IOM from HbSC and thalassemic patients showed that amounts of heme iron and, especially, free iron were much higher in patients who had undergone surgical splenectomy. The membrane AGGs from HbSS and beta-thalassemic RBCs contained much more globin than heme, with this discrepancy being variable from patient to patient. Although these AGGs were enriched (compared with the ghosts from which they were derived) for heme, as expected, less than 10% of total ghost heme was recovered in them. Remarkably, these AGGs also were enriched for nonheme iron, markedly so in some patients. Iron binding studies showed that the association of free iron with these hemichrome/band 3 AGGs is explained by the fact that free iron binds to denatured hemoglobin. These results document that free iron is nonrandomly associated with the membranes of sickle and beta-thalassemic RBCs. Whether this plays a causative role in the premature removal of such cells from the circulation remains to be seen.

Combined spectrin and ankyrin deficiency is common in autosomal dominant hereditary spherocytosis

The common autosomal dominant form of hereditary spherocytosis (HS) has been genetically linked to defects of the erythroid ankyrin gene in a few families; however, the frequency of ankyrin deficiency and its relationship to red blood cell (RBC) spectrin content are unknown. To test these questions, we measured RBC spectrin and ankyrin by radioimmunoassay in 39 patients from 20 families with dominant HS. Normal RBCs contained 242,000 +/- 20,500 spectrin heterodimers and 124,500 +/- 11,000 ankyrins per cell. In dominant HS, RBC spectrin and ankyrin ranged from about 40% to 100% of normal and were continuously distributed. Measurements in the same patient on different occasions were reproducible (+/- 5% to 10%) and RBCs from affected members of a kindred contained similar amounts of spectrin and ankyrin (+/- 3% to 4%). Spectrin and ankyrin levels were almost always less than the assay controls, but were less than the normal range in only 75% and 80% of kindreds, respectively. Remarkably, the degree of RBC spectrin and ankyrin deficiency was very similar in 19 of 20 HS kindreds. One otherwise typical family differed, with marked ankyrin deficiency (45% of control) and a relatively mild spectrin deficit (81%). We conclude that most patients with dominant HS have combined ankyrin and spectrin deficiency and that the two proteins are usually about equally deficient, suggesting that defects in ankyrin expression, ankyrin stability, or ankyrin band 3 (AE1) interactions may be common in dominant HS.

GPI Mount Scopus--a variant of glucosephosphate isomerase deficiency

Glucosephosphate isomerase (GPI) deficiency is an unusual cause of hereditary nonspherocytic hemolytic anemia. The disease, inherited as an autosomal recessive disorder, is most often manifested by symptoms and signs of chronic hemolysis, ameliorated by splenectomy. We recently diagnosed GPI deficiency in a 23-year-old Ashkenazi Jewish man who displayed the typical clinical course of this disorder. The biophysical characteristics of the GPI variant are slow electrophoretic mobility, presence of only one of the two bands normally present, and extreme thermolability. To the best of our knowledge, this is the first report of GPI deficiency in a patient of Jewish descent, and we propose to designate this enzyme variant "GPI Mount Scopus".

Envenomation by Echis coloratus (Mid-East saw-scaled viper): a review of the literature and indications for treatment

Envenomation by the snake Echis coloratus causes a local swelling and hemostatic failure. Most cases recover uneventfully, however about one-third of the victims bleed or develop anemia, and one known death due to renal failure has been reported. Uncontrolled observations suggest that treatment by a specific antivenom reduces the duration of the hemostatic failure. Still the management of victims of E coloratus remains uncertain. Some authors advocate antivenom treatment for all patients, while others recommend its use only in the event of complications. We review reported data on the effect of the venom in vitro, in laboratory animals and in humans, and reexamine alternative treatment strategies by applying a revised version of a published decision model. The probability of bleeding and the efficacy of antivenom treatment were the main determinants in the choice between antivenom treatment and expectant management of victims of E. coloratus. Assuming a therapeutic efficacy of 32%, the decision model favored antivenom treatment when the risk of bleeding exceeded 7.5%. The estimated risk of bleeding exceeds this threshold in patients who present with either proteinuria, a blood urea of > 7 mmol/l, a platelet count of < 100,000/microliters, or a hemoglobin level of < 13 g/dl. In patients who had been exposed to antiserum in the past, or in whom the annual probability of future envenomation exceeds 0.9%, antivenom treatment was preferred only when bleeding was certain. Errors in our estimates of the efficacy of antivenom treatment, of the mortality after a bleeding event and of the risk of anaphylaxis after a repeated exposure to antiserum may have affected our conclusions. Nonetheless, they are consistent with presently available information and, pending more reliable estimates, may be considered as guidelines for treatment.

Complete heart block and seizures in an adult with systemic lupus erythematosus. A possible pathophysiologic role for anti-SS-A/Ro and anti-SS-B/La autoantibodies

OBJECTIVE

To determine the serum autoantibody profile in an adult patient with systemic lupus erythematosus manifested by complete heart block (CHB) and seizures, and to investigate the source of autoantibodies found in the patient's cerebrospinal fluid (CSF).

METHODS

The serum and CSF autoantibody profiles were determined by serologic testing and Western blot studies. An antibody activity index was devised to determine the source of the autoantibodies found in the CSF.

RESULTS

The patient's serum contained anti-SS-A (52 kd and 60 kd), anti-SS-B, anti-U1 RNP, and anti-Sm autoantibodies. Studies of her CSF, however, revealed only anti-SS-A and anti-SS-B autoantibodies, with a high antibody activity index.

CONCLUSION

The finding of anti-SS-A (52 kd and 60 kd) and anti-SS-B autoantibodies was similar to reported findings in congenital CHB. Intrathecal synthesis of anti-SS-A and anti-SS-B was the source of autoantibodies found in the CSF. This patient's symptoms may be pathophysiologically linked to an immune reaction between the anti-SS-A and anti-SS-B autoantibodies and neural tissue in the brain and heart.

Posttransfusional hemolysis in recipients of glucose-6-phosphate dehydrogenase-deficient erythrocytes

To test the hypothesis that transfusion of blood donated by individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency may result in a hemolytic reaction, we conducted a prospective longitudinal study in which 10 patients transfused with 1 unit of G6PD-deficient and 1 unit of normal red blood cells (RBC) were compared with 10 patients transfused with 2 units of age-matched normal RBC. We found that 24 h after transfusion serum bilirubin (mumol/l) in the recipients of G6PD-deficient RBC was significantly higher than in the recipients of normal RBC (36 +/- 14 vs. 18 +/- 5, respectively, p > 0.004). A parallel increase was found in the serum lactate dehydrogenase (LDH; IU/l) between the two groups (378 +/- 151 vs. 264 +/- 56, p < 0.001). The difference in serum bilirubin (26 +/- 10 vs. 15 +/- 5, p < 0.03) was still noted 48 h after transfusion, with only a marginal difference (p < 0.08) in LDH. We conclude that an immediate posttransfusional hemolytic reaction can occur in recipients of G6PD-deficient RBC and therefore suggest that the differential diagnosis of posttransfusional hemolysis, particularly in populations where G6PD deficiency is prevalent, includes transfusion of erythrocytes from G6PD-deficient donors.

Primaquine-induced superoxide production by beta-thalassemic red blood cells

Primaquine, a prooxidant antimalarial drug, incubated with human red blood cells (RBC) induced marked superoxide generation in the cells as detected by exogenous cytochrome c reduction. In the presence of primaquine, beta-thalassemic RBC produced significantly more superoxide than normal RBC, thus reflecting the vulnerability of beta-thalassemic cells to oxidative stress.

Falciparum malaria-induced hypoglycaemia in a diabetic patient

We report a patient with diabetes mellitus who suffered severe falciparum malaria complicated by profound and persistent hypoglycaemia. The hypoglycaemia evolved before therapy with quinine was begun and resolved with eradication of the parasitaemia. The patient reverted to her baseline hyperglycaemia despite continuation of quinine. This case illustrates the critical role of falciparum malaria in the pathogenesis of malaria-associated hypoglycaemia, rather than quinine-mediated mechanisms. Anticipation of hypoglycaemia in falciparum malaria and its vigorous treatment may improve the poor prognosis associated with this complication.

Primary fibrinogenolysis complicating second trimester placental separation

We present a case of second trimester placental separation complicated by severe bleeding diathesis. Primary fibrinogenolysis is suggested as the cause of the coagulopathy.

Risk indicators after envenomation in humans by Echis coloratus (mid-east saw scaled viper)

To determine the frequency, severity and predictors of bleeding and azotemia after envenomation in humans by Echis coloratus, a retrospective survey of 68 cases in Israel between 1970 and 1989 was carried out. We used univariate and multivariate analyses of clinical variables on admission for the outcome variables of bleeding, hemoglobin and platelet levels, and blood urea. Within hours or days after envenomation, a major bleeding episode occurred in 18% of the victims, a drop in hemoglobin to 10 g/dliter or less in 14%, and an increase in blood urea to 9 mmole/liter or more in 15%. These complications correlated with time interval between envenomation and hospital admission, and the following admission variables: degree of bleeding, hemoglobin level, platelet and white blood cell counts, blood urea and proteinuria. Complications were unlikely in patients who were presented with all of the following: a hemoglobin level of 13 g/dliter or more, a platelet count of 100,000/mm3 or more, a blood urea level of 7 mmole/liter or less, no proteinuria and no bleeding. Treatment on admission with a specific monovalent antiserum was associated with a shorter duration of hemostatic failure and a reduced incidence of anemia and thrombopenia. Infusion of fresh frozen plasma on admission did not appear to be effective in preventing complications.

Long-term, low-dose aspirin is safe in glucose-6-phosphate dehydrogenase deficiency

Forty-four patients with Mediterranean-type glucose-6-phosphate dehydrogenase (G-6-PD) deficiency receiving long-term, low-dose aspirin were monitored over three months for evidence of hemolysis. Complete blood count, reticulocyte count and serum bilirubin were normal in all patients before treatment and upon periodic retesting. We conclude that there is sufficient current evidence to remove the hemolytic stigma of aspirin in G-6-PD deficiency, thereby establishing its safety for long-term therapy in this condition.

Multiple brain abscesses caused by Streptococcus bovis

A case of multiple brain abscesses caused by Streptococcus bovis in a 28-year-old man is described. Infected bronchiectasis is presumed to be the source of infection. Streptococcus bovis infection is a rare cause of brain abscess. The aetiology and manifestations of this infection are discussed.

Cimetidine and ranitidine may not cross-react to cause thrombocytopenia

We report the case of a patient with peptic ulcer disease who developed cimetidine-induced thrombocytopenia. The thrombocytopenia resolved spontaneously following discontinuation of cimetidine, and did not recur with ranitidine. We concluded that cimetidine and ranitidine do not necessarily cross-react to induce thrombocytopenia. Thus the exclusion of both H2-blockers in the event that one has caused thrombocytopenia may not be justified.

[Viper envenomation by Echis coloratus]

Clinical and therapeutic experience with 24 cases of envenomation by Echis coloratus, the Mideast saw-scaled viper, is reported. These cases were seen between 1979-1989 at this hospital (Mt. Scopus). A clinical classification is proposed, based on severity of the bleeding diathesis and platelet count at presentation. It is suggested as a predictor of clinical outcome and as a guide to whether antiserum should be administered.

Decreased erythrocyte (Ca2+ + Mg2+)-ATPase activity in hemodialyzed uremic patients

Erythrocyte (Ca2+ + Mg2+)-ATPase activity and calcium content were determined in 15 uremic-hemodialyzed patients and 15 normal controls. A decrease in the activity of the enzyme (mean +/- SD = 65 +/- 7 vs. 79 +/- 12 mumol Pi/g Hb/h, p less than 0.001) and a parallel increase in the calcium content (17.2 +/- 6.4 vs. 5.1 +/- 4.2 mumol/L RBC, p less than 0.05) were found in the patients' erythrocytes when compared with those of the controls. It is proposed that malfunction of the calcium pump in hemodialyzed uremic patients is pathophysiologically significant in the accumulation of intracellular calcium. The increased intracellular calcium found in other tissues in uremia may be the result of the systemic malfunction of (Ca2+ + Mg2+)-ATPase in this disorder.

Hereditary spherocytosis associated with deletion of human erythrocyte ankyrin gene on chromosome 8

Hereditary spherocytosis (HS) is one of the most common hereditary haemolytic anaemias. HS red cells from both autosound dominant and recessive variants are spectrin-deficient, which correlates with the severity of the disease. Some patients with recessive HS have a mutation in the spectrin alpha-2 domain (S.L.M. et al., unpublished observations), and a few dominant HS patients have an unstable beta-spectrin that is easily oxidized, which damages the protein 4.1 binding site and weakens spectrin-actin interactions. In most patients, however, the cause of spectrin deficiency is unknown. The alpha- and beta-spectrin loci are on chromosomes 1 and 14 respectively. The only other genetic locus for HS is SPH2, on the short arm of chromosome 8 (8p11). This does not correspond to any of the known loci of genes for red cell membrane proteins including protein 4.1 (1p36.2-p34), the anion exchange protein (AE1, band 3; 17q21-qter), glycophorin C (2q14-q21), and beta-actin (7pter-q22). Human erythrocyte ankyrin, which links beta-spectrin to the anion exchange protein, has recently been cloned. We now show that the ankyrin gene maps to chromosome 8p11.2, and that one copy is missing from DNA of two unrelated children with severe HS and heterozygous deletions of chromosome 8 (del(8)(p11-p21.1)). Affected red cells are also ankyrin-deficient. The data suggest that defects or deficiency or ankyrin are responsible for HS at the SPH2 locus.

Treatment of envenomation by Echis coloratus (mid-east saw scaled viper): a decision tree

Envenomation by Echis coloratus causes a transient hemostatic failure. Systemic symptoms, hypotension and evident bleeding are rare, with only one reported fatality. In this paper, we examine the decision to treat victims of Echis coloratus by a specific horse antiserum. The decision model considers the mortality of treated and untreated envenomation, and the side effects of antiserum treatment: fatal anaphylaxis, serum sickness and increased risk of death after a possible repeated exposure to horse antiserum in the future. The results of the analysis are not sensitive to variations in the probability of side effects of antiserum treatment. They are sensitive to variations in the risk of bleeding after envenomation, in the degree of reduction of this risk by antiserum treatment and in the risk of dying after an event of bleeding. Prompt administration of antiserum appears to be the treatment of choice if it reduces the risk of bleeding from 23.6% to 20.3% and if 1.6% or more of the bleeding events are fatal. We conclude that presently available data support antiserum treatment of victims of Echis coloratus who present with hemostatic failure, even though the advantage imparted by this treatment appears to be small.

Inadequate utilization of routine electronic RBC counts to identify beta thalassemia carriers

We investigated physician awareness of the diagnosis of beta thalassemia minor as suggested by RBC indices obtained from routine electronic counts; and, the knowledge of the carriers of their genetic trait. Out of 17,000 counts, 324 were compatible with the diagnosis of beta thalassemia minor, but, only 175 (54 per cent) were identified by physicians as possibly thalassemic and in 47 of these (27 per cent) was the diagnosis verified. Twenty-four of 39 interviewed patients in whom the diagnosis of beta thalassemia minor was established knew about their carrier state.

Calcium transport and ultrastructure of red cells in beta-thalassemia intermedia

Reported findings of elevated total calcium (Ca) contents in erythrocytes (RBCs) from patients with beta-thalassemia intermedia (beta-TI) prompted the question of whether the state and transport of Ca in these RBCs are similar to those in sickle cell anemia (SS) RBCs where the increased Ca is compartmentalized in endocytic inside-out vesicles and extracted by exposure of the cells to the Ca ionophore A23187 and a Ca chelator (ethylene glycol tetraacetic acid) and the levels of cytoplasmic free ionized Ca [( Ca2+]i) are normal. We confirmed a high total Ca content of 51 +/- 13 mumol/L RBCs in splenectomized (SPX) beta-TI and 24 +/- 1 mumol/L RBCs in non-SPX beta-TI. Unlike SS RBCs, however, most of the increased Ca was in the lighter, presumably younger beta-TI RBCs, and about half the Ca was not ionophore mobilizable but apparently firmly bound, possibly to remnants of organelles in nucleated and other young RBCs. In the denser RBCs from non-SPX beta-TI, total and extractable Ca amounts were normal. beta-TI RBCs loaded with the Ca chelator Benz 2 showed an initial influx of 45Ca in the normal range, which indicated normal Ca permeability, and near-steady-state levels of [Ca2+]i that were normal (22 +/- 7 nmol/L RBCs in non-SPX beta-TI) or minimally increased (40 +/- 19 nmol/L RBCs in SPX beta-TI). Serial-section electron microscopy of beta-TI ghosts from the denser cell fractions showed more fully enclosed vesicles in non-SPX ghosts than were seen in normal ghosts and many large vesicles and structured, electron-dense material in SPX ghosts. A delayed extrusion of ionophore-preloaded 45Ca only by the SPX beta-TI RBCs together with normal [Ca2+]i suggested compartmentalization of the loaded Ca in these RBCs, perhaps in endocytic inside-out vesicles, and normal Ca pumps. Since beta-TI RBCs show essentially normal levels of [Ca2+]i and normal Ca influx, their high total Ca content should not be associated with any of the deleterious effects observed in vitro with increased levels of [Ca2+]i.

Sickle cell trait in a white Jewish family presenting as splenic infarction at high altitude

We report the presence of sickle cell trait in several members of a white Jewish family. The trait was discovered when the propositus developed massive splenic infarction at high altitude. No erythrocyte markers characteristic of African ancestry were detected in any of the family members. This is the first bona fide documentation of sickle trait among white Jews.

Reversible busulfan-induced ovarian failure

A 26-yr-old woman with chronic myeloid leukemia developed busulfan-induced ovarian failure. The ovarian failure was manifested by amenorrhea and climacteric symptoms and was verified by elevated plasma levels of luteinizing and follicle-stimulating hormones concomitant with low 17 beta-estradiol levels. The amenorrhea proved to be reversible when, during hematological relapse one year later, the patient was found to be four months pregnant. The busulfan which she was receiving at that time was stopped and amniocentesis revealed a normal karyotype. The remainder of the pregnancy was unremarkable and was terminated by the normal delivery of a healthy child.

Failure of propranolol to improve exercise tolerance in patients with mitral stenosis in sinus rhythm

Propranolol reduces left atrial pressure at rest and during exercise in patients with mitral stenosis by lowering cardiac output and heart rate. Ten patients (aged 19-56) with moderate to severe isolated mitral stenosis were studied to determine whether propranolol increased their exercise tolerance. All were in sinus rhythm and free of left or right ventricular failure. Patients were trained in an individually graded bicycle or treadmill exercise protocol that provoked a reproducible degree of near maximal dyspnoea during the second three minute stage of exercise. Propranolol (80 mg or 120 mg) or matching placebo in two or three divided daily doses was given for one week in random double blind fashion. Exercise testing and questioning about subjective clinical response were carried out at the end of each week by an investigator who was unaware of the patient's heart rate. During propranolol treatment the heart rate was 19 beats/minute slower at rest and 38 beats/minute slower at peak exercise, but there was no change in mean exercise time to dyspnoea (274 s during propranolol vs 283 s during placebo). Four patients felt worse during the propranolol week, one patient felt better during the propranolol week, and five patients felt no difference between the two weeks. Propranolol did not improve objective or subjective exercise tolerance in patients with isolated mitral stenosis in sinus rhythm.

Erythrocyte membrane skeleton abnormalities in severe beta-thalassemia

The protein composition of ghosts, inside-out vesicles (IOV), and membrane skeletons (MS) of erythrocytes (RBC) from splenectomized (spx) and nonsplenectomized (non-spx) patients with beta-thalassemia major and beta-thalassemia intermedia was determined. Ghosts from spx thalassemia intermedia patients had a significant increase in their globin content (which was mostly heme reactive) and contained extra polypeptides in the protein 4.2 to 5 and 6-globin areas. The Triton-extracted MS from all of the thalassemic patients showed two major abnormalities: they retained up to twice the amount of protein 3 when compared with controls; they had a significant increase in their globin content, the concentration of which was independent of their protein 3 content. Analysis of the IOV revealed no differences between those prepared from normal controls and those of the patients. MS from spx thalassemia intermedia patients were grossly abnormal when examined by scanning electron microscopy and they exhibited aggregates of material that on transmission electron microscopy suggested the presence of globin precipitates. We propose that, although the integral protein composition, as reflected in the IOV, from severely affected beta-thalassemics is intact, their MS assembly is deranged. The altered skeletal structure of thalassemic RBC could result from attachment of denatured globin to the skeleton components. These abnormalities may contribute to the premature cell death seen in severe beta-thalassemia.

Masked phenytoin-induced megaloblastic anemia in beta-thalassemia minor

We report the occurrence of megaloblastic hematopoiesis with peripheral microcytosis in a beta-thalassemic heterozygote who developed profound anemia secondary to folate deficiency. The folate deficiency was precipitated by prolonged therapy with diphenylhydantoin. In thalassemic heterozygotes who develop anemia, the possibility of a megaloblastic pathogenesis should be pursued even when the RBC indices maintain their microcytic-hypochromic expression.

Inhibition of erythrocyte Ca2+-ATPase by activated oxygen through thiol- and lipid-dependent mechanisms

We have studied erythrocyte Ca2+-ATPase as a model target for elucidating effects of activated oxygen on the erythrocyte membrane. Either intracellular or extracellular generation of activated oxygen causes parallel decrements in Ca2+-ATPase activity and cytoplasmic GSH, oxidation of membrane protein thiols, and lipid peroxidation. Subsequent incubation with either dithiothreitol or glucose allows only partial recovery of Ca2+-ATPase, indicating both reversible and irreversible components which are modeled herein using diamide and t-butyl hydroperoxide. The reversible component reflects thiol oxidation, and its recovery depends upon GSH restoration. The irreversible component is largely due to lipid peroxidation, which appears to act through mechanisms involving neither malondialdehyde nor secondary thiol oxidation. However, some portion of the irreversible component could also reflect oxidation of thiols which are inaccessible for reduction by GSH, since we demonstrate existence of different classes of thiols relevant to Ca2+-ATPase activity. Activated oxygen has an exaggerated effect on Ca2+-ATPase of GSH-depleted cells. Sickle erythrocytes treated with dithiothreitol show a heterogeneous response of Ca2+-ATPase activity. These findings are potentially relevant to oxidant-induced hemolysis. They also may be pertinent to oxidative alteration of functional or structural membrane components in general, since many components share with Ca2+-ATPase both free thiols and close proximity to unsaturated lipid.

Erythrocyte (Ca+2 + Mg+2)-ATPase activity: increased sensitivity to oxidative stress in glucose-6-phosphate dehydrogenase deficiency

The effect of the thiol-oxidizing agent diamide on erythrocyte (Ca+2 + Mg+2)-ATPase activity was measured in normal and glucose-6-phosphate-dehydrogenase-deficient (G6PD-) cells. Although the enzyme activity before the oxidative stress was similar in both groups, diamide induced a markedly greater inhibition in the enzyme activity in the G6PD- cells than in the normal controls. These data indicate dependence of erythrocyte (Ca+2 + Mg+2)-ATPase, in part, on the redox status of the cell. The increased vulnerability of (Ca+2 + Mg+2)-ATPase to oxidative stress in G6PD- may be of pathophysiological relevance to their premature destruction in oxidant-induced hemolysis.