Barbara Bonamassa

Hydrodynamic Gene Delivery and Its Applications in Pharmaceutical Research

ABSTRACTHydrodynamic delivery has emerged as the simplest and most effective method for intracellular delivery of membrane-impermeable substances in rodents. The system employs a physical force generated by a rapid injection of large volume of solution into a blood vessel to enhance the permeability of endothelium and the plasma membrane of the parenchyma cells to allow delivery of substance into cells. The procedure was initially established for gene delivery in mice, and its applications have been extended to the delivery of proteins, oligo nucleotides, genomic DNA and RNA sequences, and small molecules. The focus of this review is on applications of hydrodynamic delivery in pharmaceutical research. Examples are provided to highlight the use of hydrodynamic delivery for study of transcriptional regulation of CYP enzymes, for establishment of animal model for viral infections, and for gene drug discovery and gene function analysis.

Long-term dietary administration of valproic acid does not affect, while retinoic acid decreases, the lifespan of G93A mice, a model for amyotrophic lateral sclerosis

Mice bearing the mutated gene for Cu/Zn superoxide dismutase (G93A) are a good model for human amyotrophic lateral sclerosis (ALS). They develop progressive limb paralysis paralleled by loss of motor neurons of the cervical and lumbar spinal cord, which starts at 3–3.5 months of age and ends with death at 4–5 months. Several treatments have been attempted to delay clinical symptoms and to extend lifespan, and some have had modest beneficial effects. One such treatment, based on long‐term administration of valproic acid (VPA), resulted in controversial results. We report here that, while dietary supplementation with high VPA dosage slows down motor neuron death, as assessed by measurement of a specific marker for cholinergic neurons in the spinal cord, it has no significant effect on lifespan. Recently, the hypothesis has been put forward that a deficiency of retinoic acid (RA) and its signaling may have a role in ALS. We report that long‐term dietary supplementation with RA has no effect on the decrease of the cholinergic marker in the spinal cord, but it significantly shortens lifespan of G93A mice. Muscle Nerve 39: 548–552, 2009

The roles of hepatitis B virus-encoded X protein in virus replication and the pathogenesis of chronic liver disease

Introduction: Hepatitis B virus (HBV) is a major cause of chronic liver disease (CLD) and hepatocellular carcinoma (HCC) worldwide. More than 350 million people are at risk for HCC, and with few treatment options available, therapeutic approaches to targets other than the virus polymerase will be needed. This review suggests that the HBV-encoded X protein, HBx, would be an outstanding target because it contributes to the biology and pathogenesis of HBV in three fundamental ways. Areas covered: First, HBx is a trans-activating protein that stimulates virus gene expression and replication, thereby promoting the development and persistence of the carrier state. Second, HBx partially blocks the development of immune responses that would otherwise clear the virus, and protects infected hepatocytes from immune-mediated destruction. Thus, HBx contributes to the development of CLD without virus clearance. Third, HBx alters patterns of host gene expression that make possible the emergence of HCC. The selected literature cited is from the National Library of Medicine (Pubmed and Medline). Expert opinion: Understanding the mechanisms, whereby HBx supports virus replication and promotes pathogenesis, suggests that HBx will be an important therapeutic target against both virus replication and CLD aimed at the chemoprevention of HCC.

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

BACKGROUND Chronic 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). MATERIAL AND METHODS Human 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. RESULTS As 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. CONCLUSIONS In 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.

Nonviral gene transfer as a tool for studying transcription regulation of xenobiotic metabolizing enzymes

Numerous xenobiotic metabolizing enzymes are regulated by nuclear receptors at transcriptional level. The challenge we currently face is to understand how a given nuclear receptor interacts with its xenobiotics, migrates into nucleus, binds to the xenobiotic response element of a target gene, and regulates transcription. Toward this end, new methods have been developed to introduce the nuclear receptor gene into appropriate cells and study its activity in activating reporter gene expression under the control of a promoter containing xenobiotic response elements. The goal of this review is to critically examine the gene transfer methods currently available. We concentrate on the gene transfer mechanism, advantages and limitations of each method when employed for nuclear receptor-mediated gene regulation studies. It is our hope that the information provided highlights the importance of gene transfer in studying the mechanisms by which our body eliminates the potentially harmful substances and maintains the homeostasis.

The novel radical scavenger IAC is effective in preventing and protecting against post-ischemic brain damage in Mongolian gerbils

The removal of pathologically generated free radicals produced during ischemia, reperfusion and intracranical hemorrhage seems to be a viable approach to neuroprotection. However, at present, no neuroprotective agent has proven effective in focal ischemic stroke phase III trials, despite the encouraging data in animal models. This study aimed to explore the effect of the brain penetrant low molecular weight radical scavenger bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)-decandioate (IAC) in neurological damage subsequent to ischemia-reperfusion injury in Mongolian gerbils. We examined the intraperitoneal effects of IAC on temporary bilateral common carotid artery occlusion (BCCO) by means of morphological and histological analysis of the hippocampus. Significant dose-dependent protective effects of IAC (1 to 10mg/kg b.w.) against neuropathological and morphological brain changes were seen when administered i.p. 1h before temporary BCCO in Mongolian gerbils. When administered up to 6h after BCCO, IAC actually reverses the neurodegenerative processes (e.g. hippocampal cell viability) induced by ischemia in a dose-dependent fashion. Data show that IAC is highly effective in protecting and preventing oxidative brain damage associated with cerebral flow disturbances. It is also effective even in late treatment of the insult, emphasizing its potential role for the management of ischemic stroke patients.

Redox-Based Flagging of the Global Network of Oxidative Stress Greatly Promotes Longevity

Despite more than 50 years of investigations into the free radical theory, the direct role of oxidative stress (OS) in aging and age-related diseases remains unproven. Little progress in identifying antioxidant drugs promoting longevity has been made, likely due to selectivity toward one or few radical species, variable efficacy in vivo, inherent pro-oxidant behavior of such drugs, or lack of synergism with metabolic redox homeostasis. Silencing the wide range of reactive free radicals has a great impact on OS-linked outcomes and age-related disorders. Here we show that an innovative, redox-active, multi-radical-scavenger catalytic drug delays the age-associated decline in physiological processes and markedly prolongs the mean lifespan of the adult freshwater annelids Aeolosoma viride by 170%. This unprecedented extension is associated with a decreased OS status. Consistently, treatment of annelids increases their natural resistance to oxygen-derived damage without affecting mitochondrial respiration or reproductive activity. Conversely, the superoxide dismutase (SOD)-mimetic EUK 134 that we selected as a positive control led to an increase in lifespan of ~50%, the same increase previously observed in nematodes. Our results show that reduction of the global network of OS has a profound impact on aging, prompting the development of a possible redox-based therapeutic intervention to counteract the progression of aging.

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.