Selective inhibition of the growth of human erythroid bursts by monoclonal antibodies against transferrin or the transferrin receptor

The relative requirements of colonies derived from erythroid (BFU-E) and myeloid (CFU-c) progenitors for transferrin were examined using monoclonal antibodies directed against the transferrin molecule (TF-6) or its cell surface receptor (TFR-A12, TFR1-2B). Growth of erythroid bursts was profoundly reduced at concentrations of all three antibodies that had no effect on CFU-c-derived colonies. When TFR1-2B was layered over cultures established one to seven days previously, further burst development was inhibited, and degeneration of early erythroid colonies was observed. Addition of erythropoietin augmented transferrin receptor expression on cells harvested after 1 to 2 weeks in culture and analyzed by flow cytometry. Recombinant human erythropoietin gave results comparable to those obtained in experiments using human urinary erythropoietin. Analysis of erythroblasts plucked directly from culture plates confirmed the presence of transferrin receptors on BFU-E-derived colonies. Thymidine incorporation was maximal early in the second week of culture and coincided with high transferrin receptor expression. These data demonstrate that transferrin must be available into the second week of culture to support the growth and differentiation of BFU- E-derived erythroid bursts, that the generation of erythroid colonies from BFU-E is more dependent on transferrin than myeloid colony formation from CFU-c, and that erythropoietin modulates the expression of transferrin receptors on growing bursts.     

Evaluation of AMSA in previously treated patients with acute leukemia: results of therapy in 109 adults

AMSA was evaluated in the treatment of 109 adults with previously treated acute leukemia. Of the 102 evaluable patients, 82 had AML, 17 ALL, and 3 CML in blastic phase. A number of different dose schedules of AMSA were explored, and we conclude that the optimum dose of AMSA for remission induction in acute leukemia is 120 mg/sq m/day for 5 days. Complete remissions were observed in 23 (28%) patients with AML and in 1 patient with ALL. Patients who achieved complete remission were maintained on AMSA using a dose of 30-40 mg/sq m/day for 5 days repeated at 4-wk intervals. The median duration of complete remission was 12 wk (3-59 wk), and the responders survived significantly longer than the failures (27 wk versus 8 wk, p = 0.002). The side effects associated with AMSA therapy included mild nausea and vomiting, stomatitis, diarrhea, phlebitis, alopecia, and myelosuppression-related infections. Our results indicate that AMSA is a useful new antileukemic agent for the treatment of relapsed acute leukemia and appears to have activity comparable to that of the currently available drugs, such as cytarabine and the anthracycline antibiotics.     

GSK1562590, a slowly dissociating urotensin-II receptor antagonist, exhibits prolonged pharmacodynamic activity ex vivo

BACKGROUND AND PURPOSE

Recently identified antagonists of the urotensin–II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity.

EXPERIMENTAL APPROACH

The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590, were compared using multiple bioassays.

KEY RESULTS

GSK1440115 (pK_i= 7.34–8.64 across species) and GSK1562590 (pK_i= 9.14–9.66 across species) are high affinity ligands of mammalian recombinant (mouse, rat, cat, monkey, human) and native (SJRH30 cells) UT. Both compounds exhibited >100-fold selectivity for UT versus 87 distinct mammalian GPCR, enzyme, ion channel and neurotransmitter uptake targets. GSK1440115 showed competitive antagonism at UT in arteries from all species tested (pA₂= 5.59–7.71). In contrast, GSK1562590 was an insurmountable UT antagonist in rat, cat and hUT transgenic mouse arteries (pK_b= 8.93–10.12 across species), but a competitive antagonist in monkey arteries (pK_b= 8.87–8.93). Likewise, GSK1562590 inhibited the hU-II-induced systemic pressor response in anaesthetized cats at a dose 10-fold lower than that of GSK1440115. The antagonistic effects of GSK1440115, but not GSK1562590, could be reversed by washout in rat isolated aorta. In ex vivo studies, GSK1562590 inhibited hU-II-induced contraction of rat aorta for at least 24 h following dosing. Dissociation of GSK1562590 binding was considerably slower at rat than monkey UT.

CONCLUSIONS AND IMPLICATIONS

Whereas both GSK1440115 and GSK1562590 represent high-affinity/selective UT antagonists suitable for assessing the (patho)physiological role of U-II, only GSK1562590 exhibited sustained UT residence time and improved preclinical efficacy in vivo.     

DERMAL NEUROVASCULAR DYSFUNCTION IN TYPE 2 DIABETES

The present article summarizes recent observations obtained in our laboratory which clearly indicate that sex steroids exert relevant effects on the peripheral nervous system. In particular, the following important points have emerged: (1) Steroids exert stimulatory actions on the synthesis of the proteins proper of the peripheral myelin (e.g., glycoprotein Po and peripheral myelin protein 22) in vivo and on the Schwann cells in culture; (2) in many cases the actions of hormonal steroids are not due to their native molecular forms but rather to their metabolites (e.g., dihydroprogesterone and tetrahydroprogesterone in the case of progesterone; dihydrotestosterone and 5 alpha-androstane-3 alpha,17 beta -diol in the case of testosterone); (3) the mechanism of action of the various steroidal molecules may involve both classical (progesterone and androgen receptors) and nonclassical steroid receptors (GABA, receptor); and finally, (4) the stimulatory action of steroid hormones on the proteins of the peripheral myelin might have clinical significance in cases in which the rebuilding of myelin is needed (e.g., aging, peripheral injury, demyelinating diseases, and diabetic neuropathy).     

Treatment of retinopathy of prematurity:a review of conventional and promising new therapeutic options

Retinopathy of prematurity (ROP), a retinal vascular disease of premature infants, continues to be a major cause of preventable childhood blindness all over the world. The incidence of ROP varies among countries, being influenced by the quality of the level of neonatal intensive care. Here, we discuss the potential treatments that are now available or will soon or probably be available for ROP. Although ablation of the avascular retina with laser photocoagulation remains the current gold standard and well established therapy for ROP, some new therapeutic options including angiostatic therapies are being explored based on our knowledge of the pathophysiology of the ROP and complications and efficacy of laser treatment. However, prevention of the development of severe ROP and screening for ROP seem to be the best strategy in avoiding visual impairment caused by ROP in premature infants. New therapeutic interventions including vascular endothelial growth factor antibody administration, gene therapy and supplemental therapies should be supported with evidence-based data for the treatment of ROP.     

Effects of iron deficiency versus iron deficiency anemia on brainstem auditory evoked potentials in infancy

There has been little or no evidence of brainstem auditory evoked potentials (BAEPs) among infants with iron deficiency (ID) that is not severe enough to cause anemia. To our knowledge, the effect of ID on auditory functions and/or potentials has not been investigated previously, though it seems reasonable that it should be associated with BAEP measures intermediate between those observed in iron deficiency anemia (IDA) and in iron sufficiency, considering the role of iron in myelin formation and maintenance. We therefore aimed in this study to investigate the effect of ID on BAEPs by comparing three groups of infants with ID, IDA and iron sufficiency (control) both before and after iron treatment (in iron-deficient groups). Three groups of infants (IDA, n = 25; ID, n = 24; Control, n = 44) were compared on the basis of hematological laboratory parameters and BAEP measurements both at entry into and after (12 weeks treatment with oral iron in IDA and ID groups) the study. BAEP measurements recorded at 85 dB both at entry into and after the study were not significantly different among the groups, although a sufficient response to iron treatment was achieved in iron-deficient groups (Group I and Group II). The only positive finding determined in our study was a slight decrease in latencies obtained at the end of the study when compared to the pre-study values in all three groups of the study in accordance with the expected age-dependent developmental changes. Although no negative electrophysiological effect of ID on brainstem auditory functions was found in the present study, further longer term (late childhood or adult) studies are necessary to elucidate the relationships among anemia (maybe other than IDA), ID and auditory functions, and clinical implications of hearing loss (if any) should be questioned.     

Hemolytic disease of the newborn due to isoimmunization with anti-E antibodies: a case report

Minor blood group hemolytic disease is extremely rare, since the overall potency of minor blood groups in inducing antibodies is significantly lower when compared with that of Rh (D) antigen. We hereby report a very rare case of severe neonatal anti-E hemolytic disease due to E minor blood group incompatibility. A term newborn born to a 27-year-old, gravida 3, para 3 mother was referred due to a high and increasing serum bilirubin level despite phototherapy on the 4th day of life. On admission physical examination was normal except for the jaundice, and results of the laboratory investigation demonstrated a moderate-to-severe anemia (hemoglobin 7.8 g/dl) and a severe hemolytic hyperbilirubinemia (serum total and indirect bilirubin levels 36 mg/ dl and 32.8 mg/dl, respectively; reticulocyte count 15%; and a positive direct antiglobulin test). As there was no apparent cause of the hemolytic disease such as Rh or ABO incompatibilities, further investigation (a positive indirect antiglobulin test and a positive irregular anti-E antibody in both the patient and mother, and minor blood group antigen profiles in family members compatible with E minor blood group isoimmunization) revealed the presence of anti-E hemolytic disease due to E minor blood group incompatibility. Two exchange transfusions with a 12-hour-interval were performed with minor blood group compatible fresh whole blood, and the patient was discharged in a healthy condition on the 10th postnatal day. If the most common causes of severe neonatal hemolytic disease such as Rh and ABO incompatibilities cannot be demonstrated in a newborn with significant hemolytic hyperbilirubinemia, anti-E hemolytic disease should strongly be considered in differential diagnosis. It should be kept in mind that a very severe from of minor group antibody hemolytic disease characterized by anemia and severe hyperbilirubinemia many exchange transfusions may be encountered during the course of the disease.