Myelinosome organelles in pathological retinas: ubiquitous presence and dual role in ocular proteostasis maintenance

The timely and efficient elimination of aberrant proteins and damaged organelles, formed in response to various genetic and environmental stressors, is a vital need for all cells of the body. Recent lines of evidence point out several non-classical strategies employed by ocular tissues to cope with aberrant constituents generated in the retina and in the retinal pigmented epithelium cells exposed to various stressors. Along with conventional strategies relying upon the intracellular degradation of aberrant constituents through ubiquitin-proteasome and/or lysosome-dependent autophagy proteolysis, two non-conventional mechanisms also contribute to proteostasis maintenance in ocular tissues. An exosome-mediated clearing and a myelinosome-driven secretion mechanism do not require intracellular degradation but provide the export of aberrant constituents and “waste proteins” outside of the cells. The current review is centered on the non-degradative myelinosome-driven secretion mechanism, which operates in the retina of transgenic Huntington’s disease R6/1 model mice. Myelinosome-driven secretion is supported by rare organelles myelinosomes that are detected not only in degenerative Huntington’s disease R6/1 retina but also in various pathological states of the retina and of the retinal pigmented epithelium. The intra-retinal traffic and inter-cellular exchange of myelinosomes was discussed in the context of a dual role of the myelinosome-driven secretion mechanism for proteostasis maintenance in different ocular compartments. Special focus was made on the interplay between degradative and non-degradative strategies in ocular pathophysiology, to delineate potential therapeutic approaches to counteract several vision diseases.

Metformin prevents hormonal and metabolic disturbances and 1,2-dimethylhydrazine-induced colon carcinogenesis in non-diabetic rats

Effects of two doses of the anti-diabetic drug, metformin(MF), on hormonal and metabolic levels of serum of non-diabetic male Wistar rats with 1,2-dimethylhydrazine(DMH)-induced colon tumor adenocarcinomas were studied. Carcinogenesis in the animals was also observed. Rats with DMH-induced colon adenocarcinomas had elevated levels of serum glucose, insulin, insulinlike growth factor-1, total cholesterol, triglycerides, catalase, malonic dialdehyde, glycated hemoglobin, aspartate aminotransferase,and alanine aminotransferase and decreased hemoglobin. Treatment with two doses of MF normalized majority of these changes in DMH-treated rats, whereas the drug was ineffective in rats without DMH treatment. The only exception was the decreased triglyceride levels in MF-treated rats. A 100 mg/kg dose of MF increased DMH-induced exophytic colon carcinomas and decreased endophytic tumors compared with untreated rats. Moreover, both MF doses increased DMH-induced and highly differentiated tumors and decreased the invasiveness of colon carcinomas compared with rats provided with DMH and water. Therefore, effects of MF on metabolic homeostasis are critical for preventing colon cancer.

Age-Related Changes in Probability Density Function of Pairwise Euclidean Distances between Multichannel Human EEG Signals

The probability density functions (pdf’s) and the first order structure functions (SF’s) of the pairwise Euclidean distances between scaled multichannel human EEG signals at different time lags under hypoxia and in resting state at different ages are estimated. It is found that the hyper gamma distribution is a good fit for the empirically derived pdf in all cases. It means that only two parameters (sample mean of EEG Euclidean distances at a given time lag and relevant coefficient of variation) may be used in the approximate classification of empirical pdf’s. Both these parameters tend to increase in the first twenty years of life and tend to decrease as healthy adults getting older. Our findings indicate that such age-related dependence of these parameters looks like as age- related dependence of the total brain white matter volume. It is shown that 15 min hypoxia (8% oxygen in nitrogen) causes a significant (about 50%) decrease of the mean relative displacement EEG value that is typical for the rest state. In some sense the impact of the oxygen deficit looks like the subject getting older during short-term period.

Mammalian Auditory Cortex Structure as the Basis of Cortical Sound Processing

The basic morphological aspects of auditory cortex organization in different orders of eutherian mammals are considered in the present review. The modern data describing a partitioning of mammalian auditory cortex into subfields are presented. A detailed observation of the structural organization of primary auditory cortex is given, as well as a review of recent morphological data about secondary auditory areas. Another section describes the system of auditory cortical projections. The data are considered from the perspective of possible homologies existing between the auditory cortices in different mammalian species.

Digitonin and sodium dodecylsulfate-solubilized frog rho-dopsin: Behavior under native and denaturing polyacrylamide gel electrophoresis

Rhodopsin oligomerization and dissociation in vivo and under experimental conditions is an important topic both for a basic understanding of photoreceptor structure-function but also as a potential eye disease mechanism. In this study, to estimate a state rhodopsin after solubilization with mild and harsh detergents, we applied the native (blue native-PAGE, BN- PAGE) and denaturing electrophoresis (blue-urea- PAGE, BU-PAGE;blue-SDS-PAGE, BSDS-PAGE and SDS- PAGE). After blue BN-PAGE and BSDS- PAGE, rhodopsin and opsin, respectively, were presented in gels a major band of dimer with slight contents of higher oligomers without any traces of monomer, thus testifying in favor dimer-heteromeric state of frog rhodopsin in the photoreceptor membrane. Despite all oligomer bands gave positive staining with the rhodopsin-specific monoclonal antibodies (mAb), subsequent SDS-PAGE in combination with electroelution in denaturing conditions showed that stained bands are not homogenous and besides of opsin oli-gomers contain a small admixture of proteins with unknown function. Unfolding of opsin oligomers by solubilization in SDS, as compared with folded opsin in digitonin, induces their transition to a more compact conformation. It was manifested in a more rapid migration of opsin oligomers toward to anode. Cooling of digitonin/SDS mixed extracts at 4?C for 24 hours led to a partial reverse transition of unfolded opsin dimer to initial folded conformation, thus de- monstrating the entropic nature of this transition. Opsin monomer can be observed in the gels only after harsh dissociation of oligomers under BU-PAGE or SDS-PAGE. The electro elution of the individual opsin oligomers with denaturing buffer followed by SDS-PAGE resulted in dissociation of dimer to monomers. However, unexpectedly, the trimer was dissociated to a prevailing dimer and a small portion of monomer. The products dissociation of both opsin tetramer and pentamer are difficult to determine precisely, but they are neither monomer nor dimer. Dissociation data show that the degree of opsin oli- gomerization by unknown reasons affects the pattern of dissociation of its aggregates. Obtained in this paper data indicate a need for further detailed study the obscure mechanisms of aggregation-dissociation of rhodopsin.

Erythrocyte shape transformation in physiological regulation of blood viscosity

The study was carried out to evaluate deformable and aggregative erythrocyte properties in humans under normal and pathological states and in rats exposed to various stressors. A strong correlation between the erythrocyte rheological determinants, i.e. deformability index and aggregation rate, was found under pathological and stress-induced states. The physiological significance of this phenomenon is to maintain the native structure of blood flow.

Autoimmunity in acute ischemic stroke and the role of bloodbrain barrier: the dark side or the light one?

This article presents a synopsis of the current data on the mechanisms of blood-brain barrier (BBB) alteration and autoimmune response in acute ischemic stroke. Most researchers confirm the relationship between the severity of immunobiochemical changes and clinical outcome of acute ischemic stroke. Ischemic stroke is accompanied by aseptic inflammation, which alters the brain tissue and exposes the co-stimulatory molecules of the immune system and the neuronal antigens. To date, BBB is not considered the border between the immune system and central nervous system, and the local immune subsystems are found within and behind the BBB. BBB disruption contributes to the leakage of brain autoantigens and induction of secondary autoimmune response to neuronal antigens and long-term inflammation. Glymphatic system function is altered and jeopardized both in hemorrhagic and ischemic stroke types. The receptors of innate immunity (toll-like receptor-2 and toll-like receptor-4) are also involved in acute ischemia-reperfusion injury. Immune response is related to the key processes of blood clotting and fibrinolysis. At the same time, the stroke-induced immune activation may promote reparation phenomena in the brain. Subsequent research on the reduction of the acute ischemic brain injury through the target regulation of the immune response is promising.

Autophagy is increased in cryptorchid testis resulting in abnormal spermatozoa

Autophagy is invoIved in spermatogenesis by regulating germ cell maturation.This catabolic process increases with hyperthermic conditions to prevent the accumulation of damaged organelles.Cryptorchidism is associated with impairment of germ cell maturation revealed by the presence of immature forms of sperm cells in ejaculates.The aim of the present study was to evaluate the status of autophagy in sperm cells from cryptorchid patients.Semen samples of cryptorchid patients and normozoospermic controls were analyzed by immuno cytochemistry and electron microscopy.Autophagy protei ns,autophagy-related protein 9(ATG9)and microtubule-associated protein,lA/lB-light chain 3(LC3)were localized by immunocytochemistry on the acrosome and on the equatorial segment of sperm cells.LC3 was also detected in the midpiece of cryptorchid sperm tail.Autophagy substrate p62 protein was present in the acrosome and in the postequatorial segment of sperm in control samples,but not in the cryptorchid ones.Transmission electron microscopy revealed double-membrane-limited autophagosomes in postequatorial part of spermatozoa head and midpiece in cryptorchid samples.Partly degraded mitochondria were frequently discerned in autophagic vacuoles.In conclusion,autophagy is increased in sperm cells from patients with cryptorchid history comparatively to control.Our work provides insights into the role of autophagy in the maturation and survival of human male gametes in pathological conditions.Thus,regulating autophagy could represent a potential way to improve sperm quality in cryptorchid men.