Dendritic spine degeneration:a primary mechanism in the aging process

Recent reports suggest that aging is not solely a physiological process in living beings;instead, it should be considered a pathological process or disease(Amorim et al., 2022). Consequently, this process involves a wide range of factors, spanning from genetic to environmental factors, and even includes the gut microbiome(GM)(Mayer et al., 2022). All these processes coincide at some point in the inflammatory process, oxidative stress, and apoptosis, at different degrees in various organs and systems that constitute a living organism(Mayer et al., 2022;AguilarHernández et al., 2023).

Altered Liver Gene Expression Due to Hypertension and Age in Rats

Hypertension and metabolic syndrome, both of which increase with age, are multifactorial disorders. Their etiology is complex, making it challenging to isolate involved genes. This study aimed to characterize the hepatic gene expression in spontaneously hypertensive rats (SHR) at different ages. Blood pressure in SHR was determined by tail-cuff method at one and three months of age. Hepatic RNA was isolated and gene expression was compared using microarrays. Comparison between SHR and normotensive rats revealed significant variation in gene expression: 98 genes were upregulated and 122 were downregulated in SHR;while 88 genes were upregulated and 139 genes were downregulated in age-matched normotensive rats. Furthermore, within the SHR group, 110 genes were found to be upregulated and 168 genes downregulated across different ages. Analyses via the Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathways revealed that several genes are potentially implicated in both, hypertension and metabolic syndrome. The results suggest that SHR display variations in gene expression due to aging, and when compared to normotensive rats. These variations could contribute to the development of hypertension and metabolic syndrome. Microarray studies involving older rats are necessary to further validate these findings.

Aquaporins:Their role in cholestatic liver disease

This review focuses on current knowledge on hepato-cyte aquaporins(AQPs)and their significance in bile formation and cholestasis.Canalicular bile secretion results from a combined interaction of several solute transporters and AQP water channels that facilitate water flow in response to the osmotic gradients created. During choleresis,hepatocytes rapidly increase their canalicular membrane water permeability by modulating the abundance of AQP8.The question was raised as to whether the opposite process,i.e.a decreased canalicular AQP8 expression would contribute to the development of cholestasis.Studies in several experimental models of cholestasis,such as extrahepatic obstructive cholestasis,estrogen-induced cholestasis, and sepsis-induced cholestasis demonstrated that the protein expression of hepatocyte AQP8 was impaired. In addition,biophysical studies in canalicular plasma membranes revealed decreased water permeability associated with AQP8 protein downregulation.The combined alteration in hepatocyte solute transporters and AQP8 would hamper the efficient coupling of osmotic gradients and canalicular water flow.Thus cholestasis may result from a mutual occurrence of impaired solute transport and decreased water permeability.

Hepatic drug transporters and nuclear receptors:Regulation by therapeutic agents

The canalicular membrane represents the excretory pole of hepatocytes.Bile is an important route of elimination of potentially toxic endo-and xenobiotics(including drugs and toxins),mediated by the major canalicular transporters:multidrug resistance protein 1(MDR1, ABCB1),also known as P-glycoprotein,multidrug resistance-associated protein 2(MRP2,ABCC2),and the breast cancer resistance protein(BCRP,ABCG2).Their activities depend on regulation of expression and proper localization at the canalicular membrane,as regulated by transcriptional and post-transcriptional events,respectively.At transcriptional level,specific nuclear receptors(NR)s modulated by ligands,co-activators and co-repressors,mediate the physiological requirements of these transporters.This complex system is also responsible for alterations occurring in specific liver pathologies.We briefly describe the major ClassⅡNRs, pregnane X receptor(PXR)and constitutive androstane receptor(CAR),and their role in regulating expression of multidrug resistance proteins.Several therapeutic agents regulate the expression of relevant drug transporters through activation/inactivation of these NRs.We provide some representative examples of the action of therapeutic agents modulating liver drug transporters, which in addition,involve CAR or PXR as mediators.

Dynamic localization of hepatocellular transporters in health and disease

Vesicle-based traffi cking of hepatocellular transporters involves delivery of the newly-synthesized carriers from the rough endoplasmic reticulum to either the plasma membrane domain or to an endosomal,submembrane compartment,followed by exocytic targeting to the plasma membrane. Once delivered to the plasma membrane,the transporters usually undergo recycling between the plasma membrane and the endosomal compartment,which usually serves as a reservoir of pre-existing transporters available on demand. The balance between exocytic targeting and endocytic internalization from/to this recycling compartment is therefore a chief determinant of the overall capability of the liver epithelium to secrete bile and to detoxify endo and xenobiotics. Hence,it is a highly regulated process. Impaired regulation of this balance may lead to abnormal localization of these transporters,which results in bile secretory failure due to endocytic internalization of key transporters involved in bile formation. This occurs in several experimental models of hepatocellular cholestasis,and in most human cholestatic liver diseases. This review describes the molecular bases involved in the biology of the dynamic localization of hepatocellular transporters and its regulation,with a focus on the involvement of signaling pathways in this process. Their alterations in different experimental models of cholestasis and in human cholestatic liver disease are reviewed. In addition,the causes explaining the pathological condition (e.g. disorganization of actin or actin-transporter linkers) and the mediators involved (e.g. activation of cholestatic signaling transduction pathways) are also discussed. Finally,several experimental therapeutic approaches based upon the administration of compounds known to stimulate exocytic insertion of canalicular transporters (e.g. cAMP,tauroursodeoxycholate) are described.

Reversing gastric mucosal alterations during ethanol-induced chronic gastritis in rats by oral administration of Opuntia ficus-indica mucilage

AIM： To study the effect of mucilage obtained from cladodes of Opuntia ficus-indica （Cactaceae） on the healing of ethanol-induced gastritis in rats. METHODS： Chronic gastric mucosa injury was treated with mucilage （5 mg/kg per day） after it was induced by ethanol. Lipid composition, activity of 5＇-nucleotidase （a membrane-associated ectoenzyme） and cytosolic activities of lactate and alcohol dehydrogenases in the plasma membrane of gastric mucosa were determined. Histological studies of gastric samples from the experimental groups were included. RESULTS： Ethanol elicited the histological profile of gastritis characterized by loss of the surface epithelium and infiltration of polymorphonuclear leukocytes. Phosphatidylcholine （PC） decreased and cholesterol content increased in plasma membranes of the gastric mucosa. In addition, cytosolic activity increased while the activity of alcohol dehydrogenases decreased. The administration of mucilage promptly corrected these enzymatic changes. In fact, mucilage readily accelerated restoration of the ethanol-induced histological alterations and the disturbances in plasma membranes of gastric mucosa, showing a univocal anti-inflammatory effect. The activity of 5＇-nucleotidase correlated with the changes in lipid composition and the fluidity of gastric mucosal plasma membranes. CONCLUSION： The beneficial action of mucilage seems correlated with stabilization of plasma membranes of damaged gastric mucosa. Molecular interactions between mucilage monosaccharides and membrane phospholipids, mainly PC and phosphatidylethanolamine （PE）, may be the relevant features responsible for changing activities of membrane-attached proteins during the healing process after chronic gastric mucosal damage.

Polyubiquitination inhibition of estrogen receptor alpha and its implications in breast cancer

Estrogen receptor alpha(ERα) is detected in more than 70% of the cases of breast cancer. Nuclear activity of ERα, a transcriptional regulator, is linked to the development of mammary tumors, whereas the extranuclear activity of ERα is related to endocrine therapy resistance. ERα polyubiquitination is induced by the estradiol hormone, and also by selective estrogen receptor degraders, resulting in ERα degradation via the ubiquitin proteasome system. Moreover, polyubiquitination is related to the ERα transcription cycle, and some E3-ubiquitin ligases also function as coactivators for ERα. Several studies have demonstrated that ERα polyubiquitination is inhibited by multiple mechanisms that include posttranslational modifica-tions, intera-ctions with coregula-tors, a-nd forma-tion of specific protein complexes with ERα. These events are responsible for an increase in ERα protein levels and deregulation of its signaling in breast cancers. Thus, ERα polyubiquitination inhibition may be a key factor in the progression of breast cancer and resistance to endocrine therapy.

Epigenetic basis of Alzheimer disease

Alzheimer disease(AD)is the primary form of dementia that occurs spontaneously in older adults.Interestingly,the epigenetic profile of the cells forming the central nervous system changes during aging and may contribute to the progression of some neurodegenerative diseases such as AD.In this review,we present general insights into relevant epigenetic mechanisms and their relationship with aging and AD.The data suggest that some epigenetic changes during aging could be utilized as biomarkers and target molecules for the prevention and control of AD.

Diabetic nephropathy,autophagy and proximal tubule protein endocytic transport:A potentially harmful relationship

Diabetic nephropathy(DN)is the most frequent cause of chronic renal failure.Until now,the pathophysiological mechanisms that determine its development and progression have not yet been elucidated.In the present study,we evaluate the role of autophagy at early stages of DN,induced in type 2 diabetes mellitus(T2DM)mouse,and its association with proximal tubule membrane endocytic receptors,megalin and cubilin.In T2DM animals we observed a tubule-interstitial injury with significantly increased levels of urinary GGT and ALP,but an absence of tubulointerstitial fibrosis.Kidney proximal tubule cells of T2DM animals showed autophagic vesicles larger than those observed in the control group,and an increase in the number of these vesicles marked with LBPA by immunofluorescence.Furthermore,a significant decrease in the ratio of LC3II/LC3I isoforms and in p62 protein expression in DN affected animals is shown.Finally,we observed a marked increase in urinary albumin and vitamin D binding-protein levels in T2DM animals as well as a significant decrease in expression of megalin in the renal cortex.These results indicate an alteration of the tubular endocytic transporters in DN,which could be related to autophagic dysfunction,which would in turn result in impaired organelle recycling,thus contributing to the progression of this disease.

Resveratrol effects on neural connectivity during aging

Aging has been considered a natural process of any living being.The rate of aging depends on many factors,including genetic and environmental factors.For this reason,many researchers in this field suggest that aging is an epigenetic process.Nowadays,the age groups have undergone a change.

Historical perspective of cell transplantation in Parkinson's disease

Cell grafting has been considered a therapeutic approach for Parkinson's disease(PD) since the 1980 s. The classical motor symptoms of PD are caused by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to a decrement in dopamine release in the striatum. Consequently, the therapy of celltransplantation for PD consists in grafting dopamineproducing cells directly into the brain to reestablish dopamine levels. Different cell sources have been shown to induce functional benefits on both animal models of PD and human patients. However, the observed motor improvements are highly variable between individual subjects, and the sources of this variability are not fully understood. The purpose of this review is to provide a general overview of the pioneering studies done in animal models of PD that established the basis for the first clinical trials in humans, and compare these with the latest findings to identify the most relevant aspects that remain unanswered to date. The main focus of the discussions presented here will be on the mechanisms associated with the survival and functionality of the transplants. These include the role of the dopamine released by the grafts and the capacity of the grafted cells to extend fibers and to integrate into the motor circuit. The complete understanding of these aspects will require extensive research on basic aspects of molecular and cellular physiology, together with neuronal network function, in order to uncover the real potential of cell grafting for treating PD.

Cerebral dopamine neurotrophic factor transfection in dopamine neurons using neurotensin-polyplex nanoparticles reverses 6-hydroxydopamine-induced nigrostriatal neurodegeneration

Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system,a hallmark in Parkinson's disease.The human cerebral dopamine neurotrophic factor(h CDNF)has recently emerged as a strong candidate for Parkinson's disease therapy.This study shows that h CDNF expression in dopamine neurons using the neurotensinpolyplex nanoparticle system reverses 6-hydroxydopamine-induced morphological,biochemical,and behavioral alterations.Three independent electron microscopy techniques showed that the neurotensin-polyplex nanoparticles containing the h CDNF gene,ranging in size from 20 to 150 nm,enabled the expression of a secretable h CDNF in vitro.Their injection in the substantia nigra compacta on day 21 after the 6-hydroxydopamine lesion resulted in detectable h CDNF in dopamine neurons,whose levels remained constant throughout the study in the substantia nigra compacta and striatum.Compared with the lesioned group,tyrosine hydroxylase-positive(TH^(+))nigral cell population and TH+fiber density rose in the substantia nigra compacta and striatum after h CDNF transfection.An increase inβIII-tubulin and growth-associated protein 43 phospho-S41(GAP43 p)followed TH^(+)cell recovery,as well as dopamine and its catabolite levels.Partial reversal(80%)of drugactivated circling behavior and full recovery of spontaneous motor and non-motor behavior were achieved.Brain-derived neurotrophic factor recovery in dopamine neurons that also occurred suggests its participation in the neurotrophic effects.These findings support the potential of nanoparticle-mediated h CDNF gene delivery to develop a disease-modifying treatment against Parkinson's disease.The Institutional Animal Care and Use Committee of Centro de Investigación y de Estudios Avanzados approved our experimental procedures for animal use(authorization No.162-15)on June 9,2019.

Preliminary examination of early neuroconnectivity features in the R6/1 mouse model of Huntington's disease by ultra-high field diffusion MRI

During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.

Random noise stimulation in the treatment of patients with neurological disorders

Random noise stimulation technique involves applying any form of energy(for instance,light,mechanical,electrical,sound)with unpredictable intensities through time to the brain or sensory receptors to enhance sensory,motor,or cognitive functions.Random noise stimulation initially employed mechanical noise in auditory and cutaneous stimuli,but electrical energies applied to the brain or the skin are becoming more frequent,with a series of clinical applications.Indeed,recent evidence shows that transcranial random noise stimulation can increase corticospinal excitability,improve cognitive/motor performance,and produce beneficial aftereffects at the behavioral and psychological levels.Here,we present a narrative review about the potential uses of random noise stimulation to treat neurological disorders,including attention deficit hyperactivity disorder,schizophrenia,amblyopia,myopia,tinnitus,multiple sclerosis,post-stroke,vestibular-postural disorders,and sensitivity loss.Many of the reviewed studies reveal that the optimal way to deliver random noise stimulation-based therapies is with the concomitant use of neurological and neuropsychological assessments to validate the beneficial aftereffects.In addition,we highlight the requirement of more randomized controlled trials and more physiological studies of random noise stimulation to discover another optimal way to perform the random noise stimulation interventions.

Potential role of noise to improve intracortical microstimulation in tactile neuroprostheses

The intracortical microstimulation(ICMS) from 40 to 100 μA is useful to elicit tactile sensations,which could be employed in neuroprostheses to control the robotic arms' movement.However,this electrical current applied for prolonged periods of time could damage the neuronal tissue.Therefore,there is a necessity to create new strategies for the practical use of ICMS in a safe intensity range for potential clinical applications in tetraplegic patients.Here we describe crucial studies supporting the use of electrical and optical noise to guarantee a safe ICMS delivered through brain-machine interface technologies.

Leishmaniasis in the Argentine Republic: Temporal and geographical distribution from 2013 to 2017

Objective: To assess the temporal and geographical distribution of confirmed cases of cutaneous, mucocutaneous and visceral leishmaniasis in the Argentine Republic from 2013 to 2017. Methods: A retrospective study was carried out using data collected from the Integrated Surveillance Bulletin database of the National System of Health Surveillance. Confirmed cases of cutaneous, mucocutaneous and visceral leishmaniasis up to the 52 nd epidemiological week of each year was included. Results: In the 5 years period, 1 295 confirmed leishmaniasis cases were reported in the Argentine Republic. One thousand twenty-eight(1 028) cases corresponded to cutaneous leishmaniasis(87.10%), being the most common type of leishmaniasis. Mucocutaneous leishmaniasis was in the second place in the country with 115 cases reported, mostly in the Northwest and Northeast regions. A total of 52 individuals with visceral leishmaniasis were identified and Misiones Province was the most affected. Conclusions: It is important to analyze the temporal and geographical distribution of leishmaniasis in order to provide an adequate management and surveillance.

How mind-body therapies might reduce pathological features of Alzheimer’s disease

Alzheimer’s disease(AD)is an irreversible neurodegenerat i ve disorder that i s responsible for around 60-80%of all dementia cases and currently affects around 50 million people worldwide.As the population’s life span tends to increase,current predictions suggest that by 2050,152 million people worldwide will suffer from dementia(Balsinha,2019).While the exact cause of AD remains obscure,various hypotheses regarding AD etiology have been described in the last decades.According to the amyloid hypothesis,the pathogenic changes related to AD start with the accumulation of amyloid-beta(Aβ)in the brain.These Aβpeptides form oligomers and insoluble amyloid plaques which are neurotoxic and trigger harmful downstream events such as the aggregation of the microtubule-associated protein Tau into neurofibrillary tangles,chronic inflammation,and brain atrophy.

Identification of the autotransporter Pet toxin in Proteus mirabilis strain isolated from patients with urinary tract infections

Proteus mirabilis, a motile Gram-negative bacterium, represents a common cause of complicated urinary tract infections. Autotransporters are a family of secreted proteins from Gram-negative bacteria that direct their own secretion across the outer membrane (type V autotransporter secretion mechanism). Serine protease autotransporters of Enterobacteriaceae (SPATEs) include adhesins, toxins, and proteases that can contribute to the virulence. Plasmid-encoded toxin (Pet) is the predominant protein in culture supernatants of enteroaggregative E. coli prototype strain 042 and has been extensively studied. Pet toxin is encoded on the 65-MDa adherence-related plasmid of EAEC 042 strain. In this work, Pet protein was found in the supernatant obtained from Proteus mirabilis RTX339 strain isolated from a psychiatric patient suffering complicated urinary tract infections (UTIs). The nucleotide sequence of pet gene was obtained using primers designed from E. coli 042 pet gene reported. The alignment of the sequence showed 100% identity with the pet gene reported. Is important to note that Proteus mirabilis RTX339 pet gene has chromosomal location. The chromosomal location of the gene was established since no plasmids were harbored by this strain.

Exocytosis,endocytosis and recycling of secretory vesicles in neuroendocrine cells,and its regulation by cortical actin

The cortical actin network is a mesh of filaments distributed beneath the plasmalemma that dynamically reacts in response to stimuli.This dynamic network of cortical filaments,together with motor myosin partners,adjusts the plasmalemma tension,organizes membrane protein microdomains,remodels the cell surface and drives vesicle motion in order to fine-tune exocytosis,endocytosis and recycling of secretory vesicles.In this review,we discuss how these mechanisms work in secretory cells.

The impact of paralog genes:detection of copy number variation in spinal muscle atrophy patients

Spinal muscular atrophy(SMA)is caused by dysfunction of the alpha motor neurons of the spinal cord.It is an autosomal recessive disease associated to the SMN1 gene,located in the subtelomeric region of 5q13.A paralog SMN2 gene is located at the centromeric region of the same chromosome,which apparently originated by an ancestral inverted duplication occurring only in humans.The exon sequence differs in two nucleotides in exon 7 and exon 8,which leads to an SMN2 transcript that lacks exon 7 and results in a truncated protein.Part(10%)of the SMN2 transcripts avoids the splicing of exon 7 but most of the copies are dysfunctional.In a disease scenario,the more SMN2 copies the higher possibility to restore at least partly the effects of SMN1 deficiency.Some therapeutic approaches are being developed to increase the expression of SMN2.To determine the number of SMN1 and SMN2 copies,the methodology must distinguish accurately between both genes.In this work,we present the results obtained using multiplex ligation-dependent probe amplification(MLPA)in 60 SMA suspected patients/carriers derived from different regions of Argentina.In 32 of these DNA samples we found alterations in SMN1.Among these,16 presented a heterozygous deletion(carrier status)and 14 an homozygous deletion(patient status)in exon 7 and 8 of SMN1.In one case,exon 7 was found homozygously deleted but exon 8 presented a single copy,and in another case,exon 7 was found heterozygously deleted while exon 8 was normal.Almost half of the patients(7/15)presented a normal diploid number of SMN2 while the other half(8/15)presented an increased number.In this work we showed how a probe-based methodology such as MLPA was able to distinguish between the paralog genes and determine the amount of copies in DNA samples from suspected patients/carriers of SMA.