Binding of 125I-labeled ghrelin to membranes from human hypothalamus and pituitary gland

Ghrelin has been proposed as a natural ligand of the GH secretagogue receptor(s) (GHS-R), which was an orphan receptor activated by synthetic peptidyl (hexarelin) and non-peptidyl (MK-0677) GHS to strongly release GH in animals and humans. Herein we studied: 1) the binding of 125I-labeled human ghrelin to membranes from human hypothalamus and pituitary gland; 2) the ability of human ghrelin (either octanoylated or desoctanoylated), as well as of some GHS and neuropeptides to compete with the radioligand. The saturation binding analysis showed, in both tissues, the existence of a single class of high-affinity binding sites with limited binding capacity. The Bmax (maximal number of binding sites) values of ghrelin receptors in the hypothalamus were significantly greater (p<0.001) than those detected in the pituitary, whereas the Kd (dissociation constant) values in the two tissues were similar. 125I-ghrelin bound to hypothalamic membranes was displaced by ghrelin, hexarelin, MK-0677, various GHS antagonists (EP-80317, [D-Arg1-D-Phe5-D-Trp7,9-Leu11]-substance P) and some natural (cortistatin-14) and synthetic (vapreotide) SRIH-14 agonists. In contrast, no competition was seen in the presence of GHRH-44, SRIH-14 or desoctanoylated ghrelin, a ghrelin precursor that is devoid of GH-releasing properties. In conclusion, this preliminary study firstly demonstrates that ghrelin needs octanoylation to bind its hypothalamo-pituitary receptors. These receptors are the specific binding sites for GHS and their antagonists, as well as for SRIH analogs (vapreotide and cortistatin- 14), but not for native SRIH.     

EP1572: a novel peptido-mimetic GH secretagogue with potent and selective GH-releasing activity in man

EP1572 UMV1843 [Aib-DTrp-DgTrp-CHO]) is a new peptido-mimetic GH secretagogue (GHS) showing binding potency to the GHS-receptor in animal and human tissues similar to that of ghrelin and peptidyl GHS. EP1572 induces marked GH increase after s.c. administration in neonatal rats. Preliminary data in 2 normal young men show that: 1) acute i.v. EP1572 administration (1.0 microg/kg) induces strong and selective increase of GH levels; 2) single oral EP1572 administration strongly and reproducibly increases GH levels even after a dose as low as 0.06 mg/kg. Thus, EP1572 is a new peptido-mimetic GHS with potent and selective GH-releasing activity.     

Antilymphocyte globulin, cyclosporin, and granulocyte colony- stimulating factor in patients with acquired severe aplastic anemia (SAA): a pilot study of the EBMT SAA Working Party

Patients with severe aplastic anemia (SAA) and a neutrophil (PMN) count of less than 0.5 x 10(9)/L are exposed to a high risk of early mortality when treated with antilymphocyte globulin (ALG) and steroids, with the major problem being infectious complications. The addition of human recombinant granulocyte colony-stimulating factor (rhG-CSF) to ALG may reduce early mortality by improving neutrophil counts in the short term. To test the feasibility of this approach, the SAA Working Party of the European Group for Blood and Marrow Transplantation (EBMT) designed a pilot study that included rhG-CSF (5 micrograms/kg/d, days 1 through 90), horse ALG (HALG; 15 mg/kg/d, days 1 through 5), methylprednisolone (2 mg/kg/d, days 1 through 5, then tapering the dose), and cyclosporin A (CyA; 5 mg/kg/d orally, days 1 through 180). Patients with newly diagnosed acquired SAA (untreated) and with neutrophil counts of < or = 0.5 x 10(9)/L were eligible. Forty consecutive patients entered this study and are evaluable with a minimum follow up of 120 days: the median age was 16 years (range, 2 to 72 years), the interval from diagnosis to treatment was 24 days, and the median PMN count was 0.19 x 10(9)/L. Twenty-one patients had hemorrhages, and 19 were infected at the time of treatment. Overall, treatment was well tolerated: the median maximum PMN count during rhG- CSF administration was 12 x 10(9)/L (range, 0.4 x 10(9)/L to 44 x 10(9)/L). There were three early deaths (8%) due to infection. Four patients (10%) showed no recovery, whereas 33 patients (82%) had trilineage hematologic reconstitution and became transfusion- independent at a median interval of 115 days from treatment. Median follow up for surviving patients is 428 days (range, 122 to 1,005). Actuarial survival is 92%: 86% and 100% for patients with PMN counts less than 0.2 x 10(9)/L or between 0.2 x 10(9)/L and 0.5 x 10(9)/L, respectively. This study suggests that the addition of rhG-CSF to ALG and CyA is well tolerated, is associated with a low risk of mortality, and offers a good chance of hematologic response. This protocol would appear to be an interesting alternative treatment for SAA patients with a low PMN count who lack an HLA-identical sibling.     

Interactions between killer immunoglobulin-like receptors and their human leucocyte antigen Class I ligands influence the outcome of unrelated haematopoietic stem cell transplantation for thalassaemia: a novel predictive algorithm

In a study conducted on 114 patients undergoing unrelated donor haematopoietic stem cell transplantation (HSCT) for thalassaemia, we observed that the lack of activating killer immunoglobulin-like receptors (KIRs) on donor natural killer (NK) cells significantly increased the risk of graft-versus-host disease (GvHD) [hazard risk (HR) 4.2, 95% confidence interval (CI) 1.7-10.1, P = 0.002] and transplantation-related mortality (HR 4.7, 95% CI 1.6-14.2, P = 0.01). The risk of GvHD furthermore increased when recipients heterozygous for HLA-C KIR ligand groups (C1/C2) were transplanted from donors completely lacking activating KIRs (HR 6.1, 95% CI 1.9-19.2, P = 0.002). We also found that the risk of rejection was highest when the recipient was homozygous for the C2 HLA-KIR ligand group and the donor carried two or more activating KIRs (HR 6.8, 95% CI 1.9-24.4, P = 0.005). By interpolating the number of donor activating KIRs with recipient HLA-C KIR ligands, we created an algorithm capable of stratifying patients according to the immunogenetic risk of complications following unrelated HSCT. In clinical practice, this predictive tool could serve as an important supplement to clinical judgement and decision-making.     

Phase II study of sorafenib in patients with relapsed or refractory lymphoma

The safety and activity of the multikinase inhibitor sorafenib were investigated in patients with relapsed or refractory lymphoproliferative disorders who received sorafenib (400 mg) twice daily until disease progression or appearance of significant clinical toxicity. The primary endpoint was overall response rate (ORR). Biomarkers of sorafenib activity were analysed at baseline and during treatment. Thirty patients (median age, 61 years; range, 18-74) received a median of 4 months of therapy. Grade 3-4 toxicities included hand/foot skin reactions (20%), infections (12%), neutropenia (20%) and thrombocytopenia (14%). Two patients achieved complete remission (CR), and two achieved partial remission (PR) for an ORR of 13%. Stable disease (SD) and progressive disease (PD) was observed in 15 (50%) and 11 patients (37%), respectively. The median overall survival (OS) for all patients was 16 months. For patients who achieved CR, PR and SD, the median time to progression and OS was 5 and 24 months, respectively. Compared with patients with PD, responsive patients had significantly higher baseline levels of extracellular signal-regulated kinase phosphorylation and autophagy and presented a significant reduction of these parameters after 1 month of therapy. Sorafenib was well tolerated and had a clinical activity that warrants development of combination regimens.     

Rehabilitation of chronic graft versus host disease in children. A clinical series

The study was aimed at evaluating clinical and functional assessment and results obtained following rehabilitative treatment in children affected by chronic graft versus host disease (cGVHD) after allogeneic transplantation of hemopoietic stem cells (HSCT). From 1999 to 2003 we evaluated 6 children with cGVHD after HSCT presenting severe complications and disabilities. Clinical and functional assessment was performed prior to rehabilitative treatment (T1), at follow-up at 6 (T6) and 12 (T12) months after treatment. Each child received a personalized rehabilitative treatment program based on the use of neuromotor re-education techniques, massotherapy, chest rehabilitation and occupational therapy. Six children presented sclerodermoid skin lesions, joint contractures, anchylosis, respiratory insufficiency, postural and walking alterations which led to reduction in motor performance and autonomy in daily living activity. After 1 year of rehabilitation treatment, 3 patients showed improvement in motor performance, 2 remained stable and 1 patient worsened. Rehabilitative treatment associated with pharmacological therapy has proven to be useful in patients affected by cGVHD. We believe that cGVHD is a pathology which must be seen by a physiatrist as early as possible at onset of first cutaneous signs of cGVHD to limit its invalidating evolution.     

Shiga Toxin Promotes Podocyte Injury in Experimental Hemolytic Uremic Syndrome via Activation of the Alternative Pathway of Complement

Shiga toxin (Stx)–producing Escherichia coli is the offending agent of postdiarrhea-associated hemolytic uremic syndrome (HUS), a disorder of glomerular ischemic damage and widespread microvascular thrombosis. We previously documented that Stx induces glomerular complement activation, generating C3a responsible for microvascular thrombosis in experimental HUS. Here, we show that the presence of C3 deposits on podocytes is associated with podocyte damage and loss in HUS mice generated by the coinjection of Stx2 and LPS. Because podocyte adhesion to the glomerular basement membrane is mediated by integrins, the relevance of integrin-linked kinase (ILK) signals in podocyte dysfunction was evaluated. Podocyte expression of ILK increased after the injection of Stx2/LPS and preceded the upregulation of Snail and downregulation of nephrin and α-actinin-4. Factor B deficiency or pretreatment with an inhibitory antibody to factor B protected mice against Stx2/LPS-induced podocyte dysregulation. Similarly, pretreatment with a C3a receptor antagonist limited podocyte loss and changes in ILK, Snail, and α-actinin-4 expression. In cultured podocytes, treatment with C3a reduced α-actinin-4 expression and promoted ILK-dependent nuclear expression of Snail and cell motility. These results suggest that Stx-induced activation of the alternative pathway of complement and generation of C3a promotes ILK signaling, leading to podocyte dysfunction and loss in Stx-HUS.     

High Magnesium and Sirolimus on Rabbit Vascular Cells—An In Vitro Proof of Concept

Drug-eluting bioresorbable scaffolds represent the last frontier in the field of angioplasty and stenting to treat coronary artery disease, one of the leading causes of morbidity and mortality worldwide. In particular, sirolimus-eluting magnesium-based scaffolds were recently introduced in clinical practice. Magnesium alloys are biocompatible and dissolve in body fluids, thus determining high concentrations of magnesium in the local microenvironment. Since magnesium regulates cell growth, we asked whether high levels of magnesium might interfere with the antiproliferative action of sirolimus. We performed in vitro experiments on rabbit coronary artery endothelial and smooth muscle cells (rCAEC and rSMC, respectively). The cells were treated with sirolimus in the presence of different concentrations of extracellular magnesium. Sirolimus inhibits rCAEC proliferation only in physiological concentrations of magnesium, while high concentrations prevent this effect. On the contrary, high extracellular magnesium does not rescue rSMC growth arrest by sirolimus and accentuates the inhibitory effect of the drug on cell migration. Importantly, sirolimus and magnesium do not impair rSMC response to nitric oxide. If translated into a clinical setting, these results suggest that, in the presence of sirolimus, local increases of magnesium concentration maintain normal endothelial proliferative capacity and function without affecting rSMC growth inhibition and response to vasodilators.