Objectives and methods of iron chelation therapy.

Recent developments in the understanding of the molecular control of iron homeostasis provided novel insights into the mechanisms responsible for normal iron balance. However in chronic anemias associated with iron overload, such mechanisms are no longer sufficient to offer protection from iron toxicity, and iron chelating therapy is the only method available for preventing early death caused mainly by myocardial and hepatic damage. Today, long-term deferoxamine (DFO) therapy is an integral part of the management of thalassemia and other transfusion-dependent anemias, with a major impact on well-being and survival. However, the high cost and rigorous requirements of DFO therapy, and the significant toxicity of deferiprone underline the need for the continued development of new and improved orally effective iron chelators. Within recent years more than one thousand candidate compounds have been screened in animal models. The most outstanding of these compounds include deferiprone (L1); pyridoxal isonicotinoyl hydrazone (PIH) and; bishydroxy- phenyl thiazole. Deferiprone has been used extensively as a substitute for DFO in clinical trials involving hundreds of patients. However, L1 treatment alone fails to achieve a negative iron balance in a substantial proportion of subjects. Deferiprone is less effective than DFO and its potential hepatotoxicity is an issue of current controversy. A new orally effective iron chelator should not necessarily be regarded as one displacing the presently accepted and highly effective parenteral drug DFO. Rather, it could be employed to extend the scope of iron chelating strategies in a manner analogous with the combined use of medications in the management of other conditions such as hypertension or diabetes. Coadministration or alternating use of DFO and a suitable oral chelator may allow a decrease in dosage of both drugs and improve compliance by decreasing the demand on tedious parenteral drug administration. Combined use of DFO and L1 has already been shown to result in successful depletion of iron stores in patients previously failing to respond to single drug therapy, and to lead to improved compliance with treatment. It may also result in a "shuttle effect" between weak intracellular chelators and powerful extracellular chelators or exploit the entero-hepatic cycle to promote fecal iron excretion. All of these innovative ways of chelator usage are now awaiting evaluation in experimental models and in the clinical setting.

Plasma chitotriosidase activity in patients with beta-thalassemia.

Variable increases in chitotriosidase levels have been reported in Italian patients with beta-thalassemia major and intermedia. We measured plasma chitotriosidase levels in Israeli patients with beta-thalassemia to ascertain its use as a universal marker of disease and/or response to therapy. Chitotriosidase levels in 39 adults (16-53 years; 30 with beta-thalassemia major, 9 with intermedia), and in 14 children (0.7-15 years; 12 with beta-thalassemia major, 2 with intermedia) were compared with other measures of disease, such as ferritin, hemoglobin, liver function tests, and genotype. Plasma chitotriosidase levels were normal (0.37 +/- 0.04 mU/mL) in all children. Twelve adults (31%) had elevated levels (>1.33 mU/mL): 11 patients (37%) with thalassemia major and 1 patient (11%) with thalassemia intermedia. A significant correlation was only found between plasma chitotriosidase levels and ferritin levels, and with mean number of transfusions per year. The patient with the highest chitotriosidase (1,440 nmol/mL/hr) had the highest ferritin (5,175 microg/L), required the most transfusions per year (40), and had abnormal liver tests. Normal chitotriosidase levels in the pediatric cohort and increased levels in only some adults may reflect status of iron overload in macrophages; thus there may be a role for monitoring chitotriosidase in patients with beta-thalassemia. Our results confirm results of the Italian cohort; however, in the latter, a more universal correlation was noted and chitotriosidase levels were much higher.

High prevalence of low serum vitamin B12 in a multi-ethnic Israeli population.

This study ascertained serum vitamin B12 levels among patients with Gaucher disease and among healthy Israelis. Serum B12 and metabolites' levels were studied in consecutive adult patients with Gaucher disease not treated with enzyme plus Ashkenazi Jewish neighbour-controls, together with healthy blood-donor volunteers of various ethnicities. Each group showed a high incidence of low serum B12 concentrations, with a 22.3% incidence among Ashkenazi Jews and 40% among patients with Gaucher disease. These findings raise questions on the individual and community levels of serum B12. We recommend evaluation of B12 levels among geographically contingent peoples.

Lung involvement and enzyme replacement therapy in Gaucher's disease.

Symptomatic lung involvement in Gaucher's disease is relatively rare, being restricted to patients with other severe manifestations. We describe our experience in eight of 411 patients in our referral clinic, who presented with prominent pulmonary signs or symptoms. There were four adults and four children; all have been successfully treated with enzyme replacement therapy. Routine means of monitoring pulmonary status including clinical assessment, chest X-ray, pulmonary function tests, and high-resolution CT (HRCT) were used. Enzyme treatment resulted in decreased hepatosplenomegaly, improved haematological parameters, and increased well-being; There was decreased clubbing and decreased dyspnoea in some of the patients, although on radiology, lung pathology had not normalized. All four children showed improved respiratory compliance, with significant improvement of the radiological findings in one and unchanged disease in the others. Two adults showed improvement in oxygen saturation but worsening of pulmonary hypertension. On chest X-ray, both had increased interstitial markings; one had gradual progression of pulmonary artery accentuation and fine interstitial stable pattern on HRCT. The other two adults had no change in lung function or on chest X-ray, but on HRCT there was apparent improvement in one patient. There is great heterogeneity in presentation and response to enzyme therapy in patients with Gaucher's disease and symptomatic lung involvement. Clinically, some benefited significantly from enzyme therapy, but in contrast to the dramatic reduction in organomegaly, there was no normalization in pulmonary function or lung architecture.

Viral infections and phenotypic heterogeneity in Gaucher disease.

Gaucher disease, the most common lysosomal storage disorder, is remarkable for its tremendous phenotypic heterogeneity even among patients with the same genotype. Beyond mutations at the 1q21 locus, there may be other genetic and environmental factors that impact on the natural course of Gaucher disease and indeed may trigger symptoms and signs. Among candidate events are viral infections such as the Epstein-Barr virus (EBV) or cytomegalovirus (CMV). The purpose of this study was to ascertain if indeed prior infection with EBV or CMV in patients homozygous for the most common mutation, N370S (1226G), is predictive of a more severe phenotype. Evidence for an EBV virus was IgG and IgM antibodies to early antigen and IgG anti-EBNA. For CMV infection, IgG and IgM antibodies were sought. This study failed to demonstrate any correlation between prior EBV or CMV infection and clinical course of Gaucher disease in patients homozygous for the N370S (1226G) mutation. The only positive finding was a higher level of anti-EBNA antibodies among patients with moderate/severe disease. In conclusion, other than a small subset of patients who showed a pattern comparable to immunosuppression, there was no association between severity of Gaucher disease and prior EBV or CMV infection.

A new exon 9 glucose-6-phosphate dehydrogenase mutation (G6PD "Rehovot") in a Jewish Ethiopian family with variable phenotypes.

Hereditary nonspherocytic hemolytic anemia (HNSHA) is a rare manifestation of glucose-6-phosphate dehydrogenase (G6PD) gene mutations, caused mainly by mutations located in exon 10 of the G6PD gene and less commonly by mutations in other parts of the gene. A new, exon 9, single-base mutation representing a T --> C transition at cDNA nucleotide 964 was found in three brothers and their carrier mother of Jewish Ethiopian descent. Biochemical characterization of the resultant protein was not performed. Though clinical manifestations included HNSHA in all cases, the severity of hemolysis and the transfusion requirement differed markedly. Severe congenital neutropenia (Kostmann's syndrome)--a disorder never reported before in conjunction with G6PD deficiency--was observed in one case. Levels of white blood cell G6PD activity of the three patients were 0-5% of normal controls. Neutrophil oxidative and bactericidal activities were inherently impaired in the patient with Kostmann's syndrome, but were well preserved in his two siblings.

Withdrawal of enzyme replacement therapy in Gaucher's disease.

Although enzyme replacement therapy is safe and effective in ameliorating the signs and symptoms of Gaucher's disease, some patients have withdrawn from treatment. The purpose of this study was to evaluate the response to withdrawal and to discuss the implications for patients currently on unaltered therapy regimens since the advent of treatment. Fifteen patients, who had been treated with enzyme replacement for 5-56 months and then withdrew for 8-47 months, were assessed for changes in haematological parameters and in liver and spleen index volume. Despite non-uniformity of duration of on and off periods, degree of organomegaly, anaemia and thrombocytopenia, most patients did not revert to respective baseline values in most parameters after withdrawal. None of the patients suffered exacerbation of bone involvement or had new or aggravated pulmonary hypertension. Adult patients with stable Gaucher's disease may be withdrawn from therapy for circumscribed periods without forfeiting most gains accrued during enzyme therapy. Therefore, stopping and restarting may be considered in some patients. Alternatively, maintenance at reduced dosage and/or frequency may be appropriate in some adult patients who are stable or non-responsive after the first years of enzyme therapy. This caveat does not apply to children.

Is there a correlation between degree of splenomegaly, symptoms and hypersplenism? A study of 218 patients with Gaucher disease.

Despite the prevalence of splenomegaly as a sign in many disorders, there have been no studies that correlate the degree of organomegaly with the symptoms generally ascribed to splenic enlargement. The degree of splenomegaly was compared with five overt symptoms of mechanical displacement, i.e. chronic abdominal pain, abdominal discomfort, early satiety, pain while lying on the side, or attacks of acute (colicky) left upper quadrant pains. We have also employed splenomegaly as seen in Gaucher disease as a paradigm to determine whether there is a correlation between the degree of splenomegaly and the parameters of hypersplenism. Although there was a statistically significant correlation between degree of splenomegaly and blood counts, this proved to be clinically negligible. Surprisingly, there was also no correlation between degree of splenomegaly and any of symptoms investigated.

Cytokines in Gaucher's disease.

Gaucher's disease (GD) is characterized by hepatosplenomegaly, bone marrow infiltration, osteonecrosis, which may all be associated with the presence of pathological macrophages that contain undegraded glycosphingolipids. Levels of serum cytokines, which are soluble products of mononuclear phagocytes (MNP), were evaluated in 24 GD patients. Levels of interleukin-1beta (IL-1beta), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and soluble interleukin-2 receptor (sIL-2R) in GD patients were significantly higher than in normal controls. We attempted to correlate cytokine levels with disease severity. Type I GD patients with more severe clinical manifestations had significantly higher levels of IL-1beta, IL-1Ra and IL-6, relative to type I patients with milder disease. Three patients homozygous for the 1448C mutation with neuropathic type III disease, had significantly higher levels of sIL-2R than type I patients or controls. We speculate that cytokine over-expression may relate to the pathophysiology of some of the clinical manifestations of GD. Thus, the elevated IL-1beta, TNF-alpha and IL-6 levels may induce the bone manifestations, the neutrophil chemotaxis and the increased incidence of hyper-gammaglobulinemia present in GD patients.

Platelet function abnormalities in Gaucher disease patients.

Bleeding manifestations are common in Gaucher disease patients. Although usually attributed to thrombocytopenia, some patients with relatively high platelet counts and normal coagulation tests have hemorrhagic phenomena. To investigate whether perturbed platelet function could explain these bleeding manifestations we performed platelet aggregation tests on 32 type I adult Gaucher patients who were not severely thrombocytopenic (platelet counts >50 x 10(9)/L). Seven patients (22%) had abnormal platelet aggregation. In five, platelet aggregation was markedly reduced in response to collagen and ADP and virtually absent in response to epinephrine, whereas two patients had isolated severely impaired epinephrine-induced aggregation. In one patient platelet aggregation markedly improved following one year of enzyme replacement therapy. Incubating normal platelets with high concentrations of glucocerebroside did not impair their ability to aggregate, suggesting that plasma glucocerebroside does not directly interfere with platelet function. Platelet dysfunction is a hitherto unrecognised, relatively common cause of excessive bleeding in Gaucher patients.

Gaucher's disease with valve calcification: possible role of Gaucher cells, bone matrix proteins and integrins.

Gaucher's disease, an autosomal recessive storage disease, leads to deposition of glucocerebrosides in various organs, especially those of the reticuloendothelial system. The heart is not thought to be frequently involved and studies of patients with cardiac involvement have concentrated on myocardial involvement. Despite careful prior investigation Gaucher cells have never been detected in the valves of these patients. Pathological findings of a patient with Gaucher's disease, type IIIc, with prominent cardiac valvular involvement are reported and, for the first time, the presence of Gaucher cells in the valve tissue is documented. There is evidence that the pathogenesis of the valvular injury may be by way of a cell-mediated mechanism involving bone matrix proteins and integrins.

Favism by proxy in nursing glucose-6-phosphate dehydrogenase-deficient neonates.

Two nursing neonates deficient in glucose-6-phosphate dehydrogenase developed severe hyperbilirubinemia despite phototherapy. Mothers of both the infants had recently eaten fava beans. The hemolytic triggers found in fava beans may have been absorbed by the mothers and excreted in their breast milk. Carboxyhemoglobin determination performed on one of the infants reflected ongoing hemolysis.

Low-dose low-frequency imiglucerase as a starting regimen of enzyme replacement therapy for patients with type I Gaucher disease.

The issue of the interplay of optimal dosage and frequency regimens for enzyme replacement therapy in type I Gaucher disease has been a source of controversy during the 7 years since the introduction of the placenta-derived enzymatic preparation in 1991. We present the results of treatment with the human recombinant form of the enzyme in 28 type I Gaucher patients, who have been treated for 6 to 24 months. As long as cost is an important factor in the management of patients with Gaucher disease, low-dose low-frequency imiglucerase promises satisfactory clinical improvement without compromising quality of life.