Donatella Canistro

The non-peptidyl low molecular weight radical scavenger IAC protects human pancreatic islets from lipotoxicity

BACKGROUNDnChronic exposure to high free fatty acids (FFA) can lead to irreversible damage of beta-cell accounting for impaired insulin secretion. Multiple mechanisms concur in generating the damage, but activation of oxidative stress may contribute to the final toxic effect. To better understand the phenomenon of lipotoxicity in human beta-cells, we evaluated the effects of 24-h pre-culture with 1.0 mmol/l FFA on the function, survival and mRNA expression of several enzymes involved in the generation and scavenging of reactive oxygen species (ROS).nnnMATERIAL AND METHODSnHuman islets, prepared by collagenase digestion and density gradient purification from 9 pancreases of multiorgan donors, were incubated for 24-h in the presence 1.0 mmol/l long-chain mixture (oleate:palmitate, 2:1) FFA, with or without 100 micromol/l IAC, a non-peptidyl low molecular weight radical scavenger. At the end of incubation period, insulin secretion was measured by static incubation, and mRNA expression of insulin, Cu/Zn-SOD, Mn-SOD, Catalase, Glutathione peroxidase (GSH-px) and HO-1 by quantitative Real-Time RT-PCR. Nitrotyrosine levels were determined by an ELISA technique.nnnRESULTSnAs compared to control incubation (Ctrl, no FFA), exposure to FFA was associated with impaired insulin release and reduced insulin mRNA expression. The presence of IAC in the incubation medium increased insulin release significantly and prevented changes in mRNA expression. Exposure to FFA was associated with oxidative stress as indicated by a significant accumulation of nitrotyrosine and IAC restrained such an increase. mRNA expression of Cu/Zn-SOD, Mn-SOD, Catalase, GSH-Px, and HO-1 were all modified after FFA exposure. These changes were partially prevented in the presence of IAC.nnnCONCLUSIONSnIn human islets 24-h exposure to high FFA causes oxidative stress associated with changes of several enzymes involved in ROS scavenging. These effects were prevented by the use of an antioxidant molecule.

Beneficial effect of the nonpeptidyl low molecular weight radical scavenger IAC on cultured human islet function.

We examined a possible protective effect of the nonpeptidyl low molecular weight radical scavenger IAC [bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)decanedioate di-hydrochloride] on isolated human islet cells against isolation and culture oxidative stress. Islets isolated from pancreases of nondiabetic multiorgan donors by collagenase digestion were purified by density gradient centrifugation. After the isolation, islets were either exposed or not exposed for 7 days to 10 μmol/L IAC. We found that IAC markedly reduced oxidative stress and ameliorated islets function. These results suggest that the use of IAC could be an interesting pharmacological approach for the treatment of the islets before transplantation.

Hidden Paradoxes in Generic Drug Substitution Affecting Pharmacotherapy

The issue of the generic versus brand-name drug interchangeability is an intensely debated theme historically focused on whether bioequivalence testing can guarantee therapeutic efficacy. The controversy is supported by reports of the lack of therapeutic equivalence between some generic medicinal products and brand-name drugs, as well as by a great deal of editorials expressing a negative view on generic drug substitution. This could be of particular concern for critical therapeutic categories such as psychotropic, cardiovascular, and metabolic/endocrine drugs as well as for special subpopulations such as elderly, debilitated/psychoneurotic patients, infants and children [1, 2]. To deal with this issue, large, prospective controlled evaluations have been proposed, providing information on how current bioequivalence and pharmacological equivalence translate into clinical equivalence [3]. In our opinion, however, although on one hand this strategy could be suitable in clinical trials to ascertain the “essential similarity” requirement in drug substitution—in terms of active ingredient (amount and type), route of administration, and therapeutic effectiveness—on the other hand, it might be insufficient in real practice to support the therapeutic equivalence for the general population. This could also be due to the possible influence of the marketing to patients response.

Neuroprotective properties of the non-peptidyl radical scavenger IAC in rats following transient focal cerebral ischemia

Experimental evidence suggests that reactive free radicals are generated during brain ischemia. We investigated the effect of a novel brain penetrant, low molecular weight, non-peptidyl carbon, oxygen- and nitrogen-centered radical scavenger, IAC, on infarct volume and sensory-motor performance in a rat transient middle cerebral artery occlusion model (tMCAO). Rats received 90 min tMCAO and treated with i.p. or i.v. injections of vehicle or IAC following tMCAO. Sensory-motor performance was evaluated by neuroscore tests (NS). Cerebral infarct volume was evaluated at 72 h after tMCAO. Rats treated with IAC i.p. (1 or 6 h after the onset of tMCAO) or i.v. (1 h after the onset of tMCAO) showed significant improvement in NS during the 3 or 21 day follow-up period when compared to vehicle treated rats. Cerebral infarct volumes were significantly decreased compared to vehicle in rats receiving IAC i.p. 1 h or 6 h after occlusion, approximately 30.5% decrease compared to vehicle, or i.v. 1 h after the onset of tMCAO, 48.6% decrease compared to vehicle. These results demonstrate that IAC has neuroprotective properties with a wide therapeutic window following tMCAO in rats. IAC could therefore be a candidate for the treatment of stroke.