Progress in brain research
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Over the last years, a plethora of genetic findings have completely changed our views on the aetiology of Parkinson's disease (PD). Linkage studies and positional cloning strategies have identified mutations in a growing number of genes which cause monogenic autosomal-dominant or autosomal-recessive forms of the disorder. ⋯ Thus, an increasingly complex network of genes contributing in different ways to disease risk and progression is emerging. These findings provide the 'genetic entry points' to identify molecular targets and readouts necessary to design rational disease-modifying treatments.
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Somatostatin (SS) and SS receptors (ssts) are broadly expressed in the human body where they exert many physiological actions. Moreover, they can be expressed in many pathological tissues. Particularly, a high density of ssts has been described in human neuroendocrine tumors (NETs). ⋯ Indeed, SS-analogues coupled with (111)In are used to perform sst-scintigraphy, which is a very useful first-line imaging technique in the diagnosis and follow-up of GEP-NETs. Moreover, SS-analogues conjugated to (111)In or to other radioisotopes, such as (177)Lu or (90)Y, have promising effects in the treatment of advanced NETs. ssts are expressed in some non-neuroendocrine tumors as well and in some non-tumoral diseases, suggesting that SS-analogues might have a role in the diagnosis and treatment of these pathological conditions as well. The development of novel SS-analogues with new pharmacokinetic and pharmacodynamic characteristics may further improve the clinical applications of such compounds.
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A dramatic paradigm shift is taking place in our understanding of the pathophysiology of multiple sclerosis (MS). An important contribution to such a shift has been made possible by the advances in magnetic resonance imaging (MRI) technology, which allows structural damage to be quantified in the brains of patients with MS and to be followed over the course of the disease. Modern quantitative MR techniques have reshaped the picture of MS, leading to the definition of the so- called "axonal hypothesis" (i.e., changes in axonal metabolism, morphology, or density are important determinants of functional impairment in MS). ⋯ The inflammatory and neurodegenerative components of the disease process are present from the earliest observable phases of the disease, but appear to be, at least partially, dissociated. In addition, recovery and repair play an important role in the genesis of the clinical manifestations of the disease, involving both structural changes and plastic reorganization of the cortex. This new picture of MS has important implications in the context of treatment options, since it suggests that agents that protect against neurodegeneration or promote tissue repair may have an important role to play alongside agents acting on the inflammatory component of the disease.
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Alzheimer's disease (AD) is the most prevalent form of neurodegeneration; however, therapies to prevent or treat AD are inadequate. Amyloid-beta (Abeta) protein accrues in cortical senile plaques, one of the key neuropathological hallmarks of AD, and is elevated in brains of early onset AD patients in a small number of families that bear certain genetic mutations, further implicating its role in this devastating neurological disease. In addition, soluble Abeta oligomers have been shown to be detrimental to neuronal function. ⋯ Preclinical trials in nonhuman primates, and human clinical trials using similar Abeta immunogens, are now underway. Abeta immunotherapy looks promising but must be made safer and more effective at generating antibody titers in the elderly. It is hoped that these novel immunogens will enhance Abeta antibody generation across a broad population and avoid the adverse events seen in the earlier clinical trial.
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The search for a "magic bullet" drug targeting a single receptor for the treatment of stroke or traumatic brain injury (TBI) has failed thus far for a variety of reasons. The pathophysiology of ischemic brain injury and TBI involves a number of mechanisms leading to neuronal injury, including excitotoxicity, free radical damage, inflammation, necrosis, and apoptosis. Brain injury also triggers auto-protective mechanisms, including the up-regulation of anti-inflammatory cytokines and endogenous antioxidants. ⋯ Laboratories around the world have shown that progesterone and allopregnanolone act through numerous metabolic and physiological pathways that can affect the injury response in many different tissues and organ systems. Furthermore, progesterone is a natural hormone, synthesized in both males and females, that can act as a pro-drug for other metabolites with their own distinct mode of action in CNS repair. These properties make progesterone a unique and compelling natural agent to consider for testing in clinical trial for CNS injuries including TBI and stroke.