Novel substituted aminoalkylguanidines as potential antihyperglycemic and food intake-reducing agents.

We report the synthesis and evaluation of aminoalkylguanidine analogues and derivatives in C57BL/KsJ db/db diabetic mice, following identification by random screening of 1a and 1b as potential antihyperglycemics and/or modulators of food intake. These compounds are related to galegine, a gamma,gamma-dimethylallylguanidine. Between the newly identified compounds, 1h N-(cyclopropylmethyl)- N'-(4-(aminomethyl)cyclohexylmethyl)guanidine showed the most balanced activity as antihyperglycemic and food intake-reducing agent.

L-carnitine inhibits a subset of platelet activation responses in chronic uraemia.

BACKGROUND: Activated uraemic platelets expose the aminophospholipid phosphatidylserine (PS) at their outer surface, which generates a cell procoagulant phenotype and seems at least partly due to an increase in cell caspase-3 activity. L-carnitine (LC) may decrease surface-exposed PS in stored apheresis platelets and inhibit the activity of recombinant caspases, but its effects on platelet activation response with PS externalization have not been ascertained in chronic renal failure. In the present study, we investigated in vitro and in vivo the effects of LC on PS exposure in platelets from chronic uraemic patients. METHODS: Platelet PS-exposure was assayed by flow cytometry using annexin V. Caspase activity in platelets was determined by the cleaving activity of the specific substrate DEVD-pNA and by a flow cytometric assay using rhodamine-fluorescence. The effects of LC in vivo were examined in a prospective cross-over trial including 10 patients on maintenance haemodialysis (HD) who were randomly allocated to two different treatment groups: LC (2 g i.v.) for 4 months followed by placebo (2 g i.v.) for another 4 months (group A), or placebo followed by LC (group B). RESULTS: PS-exposing platelets in blood samples obtained from HD patients were significantly higher than in healthy subjects (P<0.001) under both unstimulated and agonist-stimulated conditions. When uraemic platelets were pre-incubated with LC before agonist stimulation, platelet PS exposure proved to be significantly reduced (-13.7% for 0.5 mM LC and -25% for 5 mM LC). Pre-incubation of uraemic platelets with LC again significantly decreased the cells' caspase activity (P<0.05). In HD patients (Group A), LC supplementation was associated with a significant decrease (P<0.05) in platelet PS exposure followed by a progressive increase during treatment with placebo. In the other group of patients, while no change in platelet PS exposure was observed during the first 4 months of treatment with placebo, a significant reduction (P<0.05) in PS-positive platelets occurred after 2 and 4 months of LC therapy. CONCLUSION: Our data show that LC may reduce, possibly via inhibition of caspase activity, the exposure of PS in activated uraemic platelets. These findings may have implications for the thrombophilic tendency of uraemia.

Cellular properties of human erythrocytes preserved in saline-adenine-glucose-mannitol in the presence of L-carnitine.

L-Carnitine (LC) in the preservation medium during storage of red blood cells (RBC) can improve the mean 24-hr percent recovery in vivo and increase RBC life-span after reinfusion. The purpose of the study was to investigate the differences in the biochemical properties of RBCs stored in the presence or absence of LC, and the cell-age related responses to storage conditions and to LC. RBC concentrates in saline-adenine-glucose-mannitol (SAG-M) were stored in the presence or absence of 5 mM LC at 4 degrees C for up to 8 weeks. RBC subpopulations of different densities were prepared by centrifugation on Stractan density gradient. Cells were sampled at 0, 3, 6, and 8 weeks, and hematological and cellular properties analyzed (MCV, MCHC, 4.1a/4.1b ratio as a cell age parameter, intracellular Na(+) and K(+)). After 6 weeks, MCV of RBC stored in the presence of LC was lower than that of controls (6 weeks MCV: controls 95.4 +/- 1.8 fl; LC 91.5 +/- 2.0 fl; n = 6; P < 0.005). This was due to swelling of control cells, and affected mainly older RBCs. LC appeared to reduce or retard cell swelling. Among the osmotically active substances whose changes during storage could contribute to cell swelling, only intracellular Na(+) and K(+) differed between stored control RBCs and LC-treated cells. LC reduces the swelling of older cells during storage at 4 degrees C in SAG-M, possibly by acting on the permeability of cell membrane to monovalent cations.

Removal of uraemic plasma factor(s) using different dialysis modalities reduces phosphatidylserine exposure in red blood cells.

BACKGROUND: Solute(s) retained during uraemia cause increased exposure of aminophospholipid phosphatidylserine (PS) on the outer surface of erythrocyte membranes, and this phenomenon may be involved in the pathophysiology of uraemia by promoting abnormal erythrocyte interactions. METHODS: We examined in a prospective randomized cross-over fashion the ability of various dialysis modalities to remove the circulating uraemic factor(s) causing increased PS externalization in red cells. Each patient was treated with haemodialysis (HD) and with on-line haemodiafiltration (HDF) using standard high-flux polysulphone membranes or with the new polisulphone-based Helixone membrane to compare the effects of dialysis technique and membrane type on PS exposure. Removal of PS was assessed indirectly by measuring PS-expressing normal erythrocytes exposed to uraemic plasma or to ultrafiltrate obtained at various time points during the extracorporeal session. RESULTS: Removal of the uraemic plasma factor(s) causing PS exposure was demonstrated by the reduced ability of uraemic plasma at the end of dialysis to induce PS exposure in normal erythrocytes, and by the capacity of ultrafiltrate from the dialysate side of the dialyzer membrane to markedly increase PS-positive red cells. However, the degree of removal varied according to the dialyzer type and to dialysis technique. Removal was greater for on-line HDF using the Helixone membrane, intermediate and comparable with HD with Helixone and with on-line HDF using standard polysulphone, and lower for HD using polysulphone membrane. The putative uraemic compound causing PS exposure seems to be highly lipophilic, somehow associated with plasma proteins, and apparently having a molecular weight between 10 and 10.8 kDa. CONCLUSIONS: Uraemia is associated with retention of compound(s) that are lipophilic, possibly protein-bound and which cause an abnormal exposure of PS in erythrocytes. Our findings, that such compound(s) can be removed during dialysis and at higher rates with convection techniques, indicate a potential benefit for uraemic patients. The present results also seem to confirm the marked ability of high-flux Helixone membranes to eliminate high molecular weight solutes.