Acetylsalicylic acid--induced hemolysis and its mechanism.

Acetylsalicylic acid (ASA) is known to cause severe hemolytic anemia in some glucose-6-phosphate-dehydrogenase-deficient (G-6-PD-deficient) individuals. To study its mechanism, erythrocytes from an ASA-sensitive patient were transfused into a normal compatible recipient. The administration of 2,5-dihydroxybenzoic (gentisic) acid, a known ASA metabolite with redox properties, to the recipient resulted in a marked decrease in the survival of the patient's erythrocytes. Similar studies with red cells from individuals with A- and Mediterranean variants of G-6-PD revealed no alteration in the erythrocytes' survival. Further studies disclosed that both salicylate and gentisate competitively inhibited the G-6-PD from the ASA-sensitive patient resulting in a marked change in the K(m) for NADP. These drugs also inhibited the A- and Mediterranean variants of G-6-PD. The magnitude of inhibition, however, was comparatively small and not different from that observed with a normal enzyme. The above studies suggested that enzyme inhibition by salicylate and gentisate may play an important role in ASA-induced hemolysis. Such an inhibition would further curtail NADPH regeneration, rendering the cells more vulnerable to oxidants. In this connection, gentisate seems to play a major role in ASA-induced hemolysis for it is both a G-6-PD inhibitor and an "oxidant."

Lymphocyte dysfunction in congenital hypoplastic anemia.

Congenital hypoplastic anemia (Diamond-Blackfan syndrome) is thought to involve the erythropoietic cell line alone. In this study, the evaluation of lymphocyte function in five patients with this syndrome revealed a number of abnormalities. Peripheral blood T lymphocyte percentages as assessed by monoclonal antibodies were decreased in three patients. T-helper/T-suppressor cell (OKT4:OKT8) ratios were almost unity in four of the five patients. We usually find a ratio of 2:1 in normal populations. Studies of lymphocyte-mediated suppression of lymphoproliferation demonstrated an inability to generate concanavalin A-induced suppressor cells in the same four patients and impaired prostaglandin-mediated suppression in two patients. Co-culture studies revealed a T lymphocyte-mediated suppression of erythropoiesis in a single patient, who also showed suppression of the mixed lymphocyte reaction. The four remaining patients showed no excessive suppressor effects either upon erythropoiesis or lymphoproliferation. These studies demonstrate that in congenital hypoplastic anemia, the cellular defect is not restricted to the erythroid progenitor cells, but extends to the lymphocytes.

Effects of recombinant human interferon gamma on hematopoietic progenitor cell growth.

Human bone marrow BFU-E, CFU-E, and CFU-GM were cultured in the presence of varying concentrations of recombinant human interferon gamma (rHuIFN-gamma). Concentration-dependent inhibition of both erythroid and myeloid precursors by rHuIFN-gamma was demonstrated. A more pronounced suppressive effect of rHuIFN-gamma was seen on the BFU-E than on the CFU-E, with CFU-GM most resistant. rHuIFN-gamma was also added at varying time points during the marrow cultures, demonstrating different time-dependent sensitivities to rHuIFN-gamma; CFU-E were no longer sensitive to rHuIFN-gamma by day 2 of culture, BFU-E by day 6, and CFU-GM by day 9, indicating a loss of sensitivity with maturation. Finally, exposure of marrow cells to rHuIFN-gamma for varying periods of time prior to initiation of hematopoietic cultures failed to inhibit erythroid colony growth in the absence of rHuIFN-gamma in the culture. These studies demonstrate a suppressive effect of rHuIFN-gamma on human erythroid and myeloid progenitor cell growth. This effect appears to be most pronounced on the more primitive stages of committed progenitor cell development.

Cytokine transgene expression and promoter usage in primary CD34+ cells using particle-mediated gene delivery.

Induction or short-term transgenic expression of specific cytokines, growth factors, or other candidate therapeutic genes in hematopoietic progenitor or stem cells is potentially applicable to gene therapy for cancer. In this study, we explored the application of a gene gun technique, as an alternative to viral vectors, for ex vivo gene transfer into and transient gene expression in highly enriched CD34+ cells derived from human umbilical cord blood. Twenty-four hours posttransfection, 32.6 to 1500 pg/l x 10(6) CD34+ cells of transient gene expression was routinely obtained for specific cytokine and reporter genes. Transgene expression at the single-cell level was revealed by X-Gal staining of lacZ cDNA-transfected CD34+ cells. Expression of four candidate therapeutic genes, namely human granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, interleukin 2, and interferon gamma, was detectable for 4 to 7 days in CD34+ cells. A human elongation factor 1alpha promoter/intron 1 transcription unit was identified as a strong cellular promoter for CD34+ cells, exhibiting strength similar to that of the commonly employed cytomegalovirus immediate-early promoter. These results suggest that the nonviral, gene gun technique offers an efficient alternative approach for transient transgenic studies of hematopoietic cells and may provide new possibilities for certain cancer gene therapy strategies using CD34+ cells.

Somatic mosaicism in Fanconi anemia: molecular basis and clinical significance.

Approximately 25% of patients with Fanconi anemia (FA) have evidence of spontaneously occurring mosaicism as manifest by the presence of two subpopulations of lymphocytes, one of which is hypersensitive to cross-linking agents (e.g. mitomycin C) while the other behaves normally in response to these agents. The molecular basis of this phenotypic reversion has not yet been determined. We have investigated 8 FA patients with evidence of mosaicism. Epstein-Barr virus-immortalized lymphoblastoid cell lines established from these patients exhibited an IC50 for mitomycin C of 25 to > 100 nM compared to a mean of 2 +/- 2 nM for 20 nonmosaic FA patients and 49 +/- 11 nM for 8 healthy controls. In 3 patients who were compound heterozygotes for pathogenic FAC gene mutations the molecular mechanism of the mosaicism was investigated by haplotype analysis. The results indicated that an intragenic mitotic recombination must have occurred leading to a segregation of a wild-type allele in the reverted cells and suggested two patterns of recombination. In 1 patient a single intragenic crossover between the maternally and paternally inherited mutations occurred associated with markers located distally to the FAC gene; in the other 2 patients (sibs) the mechanism appears to have been gene conversion resulting in segregants which have lost one pathogenic mutation. In 6 of the 8 patients the hematological symptoms were relatively mild despite an age range of 9-30 years.

Androgen dependency in acquired aplastic anemia.

We describe three patients with acquired aplastic anemia showing dependency on androgens, with blood counts that correlated directly with variation in oxymetholone dosage. In two of the patients, red cells, neutrophils and platelets showed parallel fluctuations, whereas in one patient the red cells and white cells, but not the platelets, fluctuated in relationship to oxymetholone therapy. There was no hematologic response to dromostanolone in two patients. These results support the benefit of androgen therapy in some patients with acquired aplastic anemia.

Phlebotomy with iron therapy to correct the microcytic polycythemia of chronic hypoxia.

Patients with chronic hypoxia develop a physiologically appropriate "secondary" polycythemia that improves oxygen carrying capacity. Supplemental iron is often required to maintain this. In severe cases when hematocrit levels approach 70%, iron is withheld in order to avoid dangerously high hematocrit levels and the risks of vascular sludging due to "hyperviscosity." Some patients even require reduction of viscosity by exchange of their polycythemic blood for plasma when symptoms develop. Iron deficiency with microcytic polycythemia can then develop. Management of such patients is unclear. Continued blood withdrawal will worsen the iron deficiency; iron supplementation will increase the hematocrit level and the risks of hyperviscosity. The combination of frequent phlebotomy with oral iron therapy should improve iron stores while safely maintaining a stable hematocrit level in patients with microcytic polycythemia. This combination should also have multiple beneficial effects on tissue oxygen delivery and utilization. This approach has been discussed and used for a patient with microcytic polycythemia due to Eisenmenger syndrome. While on therapy the patient's clinical symptoms decreased, and his serum iron level, hematologic indices, and treadmill tolerance tests all improved.

Synergistic and antagonistic effects of combinations of cyclosporine A and its metabolites on inhibition of phytohemagglutinin-induced lymphocyte transformation in vitro.

Cyclosporine A (CsA) and purified CsA metabolites were tested alone and in combination in cell culture to determine their effects on phytohemagglutinin (PHA)-induced lymphocyte proliferation. CsA was significantly more inhibitory than its metabolites at all concentrations tested (0-1000 ng/mL). CsA exerted maximum inhibition (70% decrease in [methyl-3H]thymidine incorporation) at concentrations of 300 ng/mL or greater; metabolites M1, M17, and M21 depressed the response 46, 39, and 23%, respectively, at 300 ng/mL. Metabolites M8, M18, M26, M25, M13, and M203-218 were non-inhibitory. When combinations of M17 and CsA were tested for the effects on PHA-induced lymphocyte transformation, a synergistic effect occurred at combinations of low concentrations of M17 and CsA and an antagonistic effect at the higher concentrations. Of the 49 combinations of CsA and M17 tested, 30 were antagonistic, 16 synergistic and 3 undecided (approaching addition). When 49 combinations of CsA and the non-immunosuppressive metabolite M8 were tested, 29 of the 49 combinations were synergistic, 17 antagonistic, 1 additive and 2 undecided (approaching addition). Of the 29 synergistic combinations, 14 were strongly synergistic. The importance of the interaction of CsA and metabolites to the immunopharmacology of CsA therapy is discussed.

Inhibitory effect of leukemic plasma on periodate-induced lymphocyte transformation.

Plasma from nine out of 18 patients with untreated acute lymphoblastic leukemia (ALL) depressed the transformation of normal blood lymphocytes induced by sodium periodate (NaIO4) as judged by reduction of blast cell formation and [3H]thymidine and [3H]uridine incorporation into DNA and RNA respectively. The depressed mitogen responsiveness of lymphocytes cultured in the presence of leukemic plasma was due to the presence of inhibitory factor(s) present in the plasma rather than the absence of components present in normal plasma. The inhibitory effect of leukemic plasma on periodate-induced cell stimulation indicated that the leukemic plasma inhibitory factor(s) exert their action very rapidly and directly on the cell. Transfer of the inhibitory factor(s) from the leukemic plasma to the cultured cells was supported by the finding that the depressive action of leukemic plasma on lectin and non-lectin mitogen-induced transformation of lymphocytes was reduced if the leukemic plasma was preincubated with either resting or mitogen-treated lymphocytes prior to testing with lymphocytes not previously exposed to leukemic plasma or mitogen.

A boy with congenital malformations and chromosome breakage.

A patient with increased chromosome breakage and multiple congenital malformations is described. The lack of any apparent quantitative or qualitative disturbance in hemopoiesis and adequate number of myeloid and erythroid progenitor cells and the absence of certain clinical features such as webbed neck and absence of dark pigmentation in the patient did not support the diagnosis of the Fanconi pancytopenia syndrome. The cytogenetic studies revealed increased chromosome breakage at G1 phase, a finding which is also at variance with that observed in patients with the Fanconi pancytopenia syndrome.

A review of the chemistry, biological action, and clinical applications of anabolic-androgenic steroids.

BACKGROUND: Since its discovery in 1935, numerous derivatives of testosterone have been synthesized, with the goals of prolonging its biological activity in vivo, producing orally active androgens, and developing products, commonly referred to as anabolic-androgenic steroids (AAS), that are more anabolic and less androgenic than the parent molecule. OBJECTIVE: This article reviews the structure, biotransformation, and mechanism of action of testosterone and some of the most commonly used AAS. Clinical applications of the AAS are discussed, and guidelines and therapeutic maneuvers for minimizing their side effects are outlined. METHODS: Literature for inclusion in this review was identified using the libraries of the University of Wisconsin Medical School and School of Pharmacy, the author's files, and searches of MEDLINE, Science Citation Index, Biological Abstracts, and Chemical Abstracts. RESULTS: The myotrophic action of testosterone and its derivatives and their stimulatory effects on the brain have led to widespread use of AAS by athletes and "recreational" drug users. Consequently, all AAS were classified as class III controlled substances in 1991. Nonetheless, AAS have shown benefit in a variety of human disorders, including HIV-related muscle wasting and other catabolic conditions such as chronic obstructive pulmonary disease, severe burn injuries, and alcoholic hepatitis. Because of their diverse biological actions, AAS have been used to treat a variety of other conditions, including bone marrow failure syndromes, constitutional growth retardation in children, and hereditary angioedema. AAS therapy is associated with various side effects that are generally dose related; therefore, illicit use of megadoses of AAS for the purpose of bodybuilding and enhancement of athletic performance can lead to serious and irreversible organ damage. The most common side effects of AAS are some degree of masculinization in women and children, behavioral changes (eg, aggression), hepatotoxicity, and alteration of blood lipid levels and coagulation factors. CONCLUSIONS: To minimize or avoid serious toxicities with AAS therapy, close medical supervision and periodic monitoring are important, with dose adjustment as appropriate to achieve the minimum effective dose. Given the biological effects and potential adverse effects of AAS, administration of these agents should be avoided in pregnant women, women with breast cancer or hypercalcemia, men with carcinoma of the prostate or breast, and patients with nephrotic syndromes or significant liver dysfunction.

The role of aminocaproic acid in lacrimal surgery in dyskeratosis congenita.

A 14-year-old boy with bilateral epiphora since birth had absent lacrimal puncta, oral leukoplakia, agenesis of the nails, cutaneous dyschromia, and pancytopenia, findings noted in the rare syndrome of dyskeratosis congenita. Bilateral conjunctivodacryocystorhinostomy was complicated by persistent hemorrhage despite preoperative platelet transfusion. The hemorrhage was controlled by administration of an antifibrinolytic agent, aminocaproic acid. Lacrimal excretory anomalies may be the initial manifestation of a serious systemic disorder, dyskeratosis congenita. Surgical management in this disorder should include appropriate hematologic support.