Molecular Effects of L-dopa Therapy in Parkinson’s Disease

Parkinson’s disease (PD) is one of the most common neurological diseases in elderly people. The mean age of onset is 55 years of age, and the risk for developing PD increases 5-fold by the age of 70. In PD, there is impairment in both motor and nonmotor (NMS) functions. The strategy of PD motor dysfunction treatment is simple and generally based on the enhancement of dopaminergic transmission by means of the L-dihydroxyphenylalanine (L-dopa) and dopamine (DA) agonists. L-dopa was discovered in the early -60''s of the last century by Hornykiewicz and used for the treatment of patients with PD. L-dopa treatment in PD is related to decreased levels of the neurotransmitter (DA) in striatum and ab-sence of DA transporters on the nerve terminals in the brain. L-dopa may also indirectly stimulate the receptors of the D1 and D2 families. Administration of L-dopa to PD patients, especially long-time therapy, may cause side effects in the form of increased toxicity and inflammatory response, as well as disturbances in biothiols metabolism. Therefore, in PD pa-tients treated with L-dopa, monitoring of oxidative stress markers (8-oxo-2’-deoxyguanosine, apoptotic proteins) and in-flammatory factors (high-sensitivity C-reactive protein, soluble intracellular adhesion molecule), as well as biothiol com-pounds (homocysteine, cysteine, glutathione) is recommended. Administration of vitamins B6, B12, and folates along with an effective therapy with antioxidants and/or anti-inflammatory drugs at an early stage of PD might contribute to improvement in the quality of the life of patients with PD and to slowing down or stopping the progression of the disease.     

Molecular docking study on the “back door” hypothesis for product clearance in acetylcholinesterase

Acetylcholinesterase (AChE) is one of the fastest enzymes known, even though the active site is buried inside the protein at the end of a 20-A deep narrow gorge. Among the great variety of crystal structures of this enzyme, both in the absence and presence of various ligands and proteins, the structure of a complex of AChE with the pseudo-irreversible inhibitor Mf268 is of particular interest, as it assists in the proposal of a back door for product clearance from the active site. Binding of Mf268 to AChE results in the carbamoylation of Ser200 and liberation of an eseroline-fragment as the leaving group. The crystal structure of the AChE-Mf268 complex, however, proves that eseroline has escaped from the enzyme, despite the fact that the Ser-bound inhibitor fragment blocks the gorge entrance. The existence of alternative routes other than through the gorge for product clearance has been postulated but is still controversially discussed in the literature, as an experimental proof for such a back door is still missing. We have used Monte Carlo-based molecular docking methods in order to examine possible alternative pathways that could allow eseroline to be released from the protein after being cleaved from the substrate by Ser200. Based on our results, a short channel at the bottom of the gorge seems to be the most probable back-door site, which begins at amino acid Trp84 and ends at the enzyme surface in a cavity close to amino acid Glu445. [Figure: see text].     

Molecular Basis of Etiological Implications in Alzheimer’s Disease: Focus on Neuroinflammation

Significant bodies of evidences have shown different mechanisms known to be the etiological cause of Alzheimer’s disease (AD) involving amyloid-beta protein accumulation, chronic inflammatory reactions, oxidative stress, proteasome inhibition, and high-cholesterol level, but the presize etiology of AD still remains enigmatic. Recent studies indicate that these mechanisms seem to be interlinked, and neuroinflammation emerges as a major regulatory and commen factor in all these mechanisms. In amyloid-beta protein, induced neurodegenerative hypothesis of AD inflammatory cytokines IFN-γ, TNF-α, interleukin (IL)-1α plays an important role in the progression of the disease. In cholesterol induced hypothesis liver X receptor mediated IL-4 also plays a major role in the progression of neuroinflammation. Notably, Omi and HtrA2 proteases play very important functions in neuronal dysfunction, which may lead to neurodegeneration. Further at genetic level, alterations in the genes occur especially in APP, PSEN1, PSEN2, APO E(ε4), ADAM12, and SH3MD1 which mediate neurodegeneration. Additionaly, The role of SP-1, NF-κB, and BCAE-1 is critical in the regulation of neuroinflammation-associated disease pathogenesis. All together, in this review, we discus the importance of neuroinflammatory mediators and their mechanistic role in the process of AD neurodegeneration.     

Dad’s Snoring May Have Left Molecular Scars in Your DNA: the Emerging Role of Epigenetics in Sleep Disorders

The sleep-wake cycle is a biological phenomena under the orchestration of neurophysiological, neurochemical, neuroanatomical, and genetical mechanisms. Moreover, homeostatic and circadian processes participate in the regulation of sleep across the light–dark period. Further complexity of the understanding of the genesis of sleep engages disturbances which have been characterized and classified in a variety of sleep–wake cycle disorders. The most prominent sleep alterations include insomnia as well as excessive daytime sleepiness. On the other side, several human diseases have been linked with direct changes in DNA, such as chromatin configuration, genomic imprinting, DNA methylation, histone modifications (acetylation, methylation, ubiquitylation or sumoylation, etc.), and activating RNA molecules that are transcribed from DNA but not translated into proteins. Epigenetic theories primarily emphasize the interaction between the environment and gene expression. According to these approaches, the environment to which mammals are exposed has a significant role in determining the epigenetic modifications occurring in chromosomes that ultimately would influence not only development but also the descendants’ physiology and behavior. Thus, what makes epigenetics intriguing is that, unlike genetic variation, modifications in DNA are altered directly by the environment and, in some cases, these epigenetic changes may be inherited by future generations. Thus, it is likely that epigenetic phenomena might contribute to the homeostatic and/or circadian control of sleep and, possibly, have an undescribed link with sleep disorders. An exciting new horizon of research is arising between sleep and epigenetics since it represents the relevance of the study of how the genome learns from its experiences and modulates behavior, including sleep.     

Hodgkin’s disease in the spleen

Spleens with proven though small Hodgkin lesions were examined expecially in relation to the lymphoid tissue normally engaged in the immune response. These Hodgkin foci were always very close to small arteries and surrounded by a lymphocyte corona. Most of the red and white pulp seemed normal, but in some instances abnormal looking large and also multinucleated cells were found scattered through the p.a.l.s. and especially through some follicles. It is considered possible that these isolated cellular abnormalities in the white pulp, when associated with pre-existent Hodgkin foci, represent early Hodgkin lesions. The implications for the dissemination of the disease are discussed. Spread of malignant cells to the spleen is only acceptable within the concept of a homing principle. It is also possible that the lesions arise "de novo". The nature of the observed abnormal cells is not clear. An explanation for the origin of these Sternberg-Reed-like cells from B-lymphocytes would be in accordance with recent data, but another possibility still is that they originate from antigen trapping cells.