Accumulation Of Lipofuscin Granules Research Articles

Regulation of the apoptosis/autophagy switch by propionic acid in ventromedial hypothalamus of rats with type 2 diabetes mellitus

BackgroundHypothalamic dysregulation may cause abnormal glucose metabolism and type 2 diabetes mellitus (T2DM). The balance between autophagy and apoptosis is important for maintaining cellular/tissue homeostasis and may be disrupted in T2DM. ObjectivesSince propionic acid (PA) exerts neuroprotective effects, the aim was to investigate its effects on apoptosis/autophagy switch in the ventromedial hypothalamus (VMH) of T2DM rats. Materials and methodsMale Wistar rats were divided: 1) control; 2) T2DM; groups that received (14 days, orally): 3) metformin (60 mg/kg); 4) sodium salt of PA (60 mg/kg); 5) PA + metformin. Western blotting (Bax, Bcl-xl, LC3, Beclin-1, caspase-3), RT-PCR (Bax, Bcl-xl, LC3, Beclin-1), transmission electron microscopy and immunohistochemical staining (Bax, Bcl-xl) were performed on the VMH samples. ResultsT2DM-induced apoptosis and mitoptosis, enlarged endoplasmic reticulum (ER) tubules/cisterns were observed in VMH, and accompanied by an imbalance of pro- and anti-apoptotic factors: elevation of pro-apoptotic markers Bax and caspase-3, decrease in autophagy protein LC3 and anti-apoptotic Bcl-xl. Metformin and PA administration partially improved VMH ultrastructural changes by reducing mitochondrial swelling and diminishing the number of apoptotic neurons. Metformin inhibited neuronal apoptosis, however, caused reactive astrogliosis and accumulation of lipofuscin granules. Elevated number of autophagosomes was associated with the LC3, Beclin-1 and Bcl-xl increase and decrease in Bax and caspase-3 vs. T2DM. PA switched cell fate from apoptosis to autophagy by elevating LC3 and Beclin-1 levels, increasing Bcl-xl content that altogether may represent adaptive response to T2DM-induced apoptosis. PA + metformin administration lowered relative area of ER membranes/cisterns vs. control, T2DM and metformin, and was optimal considering ratio between the pro-apoptotic, anti-apoptotic and autophagy markers. ConclusionT2DM was associated with apoptosis activation leading to impairments in VMH. PA in combination with metformin may be effective against diabetes-induced cell death by switching apoptosis to autophagy in VMH.

Infl uence of coal-rock dust on the risk of developing morphological disorders of the cardiovascular system

Cardiovascular pathology prevails in the structure of somatic diseases of miners. As a complication of pneumoconiosis, the development of a chronic pulmonary heart in workers against the background of pulmonary hypertension and congestive heart failure is considered. Data from clinical studies also indicate remodeling of the blood vessel wall, the formation of atherosclerosis, endothelial dysfunction and others. There are practically no in-depth comprehensive studies on the contribution of industrial dust to the development and course of this pathology. To implement this task, the simulation of occupational diseases in animals helps to trace the dynamics of the pathological process from the moment of exposure to the body of the production factor.The aim of the study is to study the infl uence of coal-rock dust on the risk of developing morphological disorders of the cardiovascular system in an experiment.Experiments were conducted on white non-linear male rats that were exposed to inhaled coal-rock dust of the “gas-fat” brand. For histological study in animals aft er 1, 3, 6, 9 and 12 weeks of exposure to the damaging factor, fragments of the brain, lungs, heart, liver and kidneys were taken. The quantitative content of matrix metalloproteinases, their inhibitor and vascular endothelial growth factor in blood plasma was studied using enzyme immunoassay.Morphological changes in the heart muscle and blood vessels are a systemic response of the body to prolonged inhalation of coal-rock dust. Violations develop from the moment of exposure to the damaging factor, so they can be considered as one of the manifestations of pneumoconiosis, and not its late complication. In the early stages of the experiment (1-3 weeks), the development of diff use protein dystrophy of cardiomyocytes with pronounced thickening of some fi bers due to cell hypertrophy is noted in the heart muscle of experimental animals. Increasing the timing of seed leads to the progression of pathological changes, increased apoptotic activity of cells and the accumulation of lipofuscin granules in the perinuclear zone, as well as the formation of atrophic damage in muscle tissue. By the 12th week of the experiment, diff use cardiosclerosis and pronounced dystrophy of cardiomyocytes with fragmentation and myocytolysis of individual sections of muscle fi bers develop in the heart muscle. Long-term inhalation of coal-rock dust causes progressive development in the wall of blood vessels, regardless of their organ affi liation, of the same type of pathological changes in the form of endotheliosis, diff use hypertrophy of the smooth muscle component of the medial layer and perivascular fi brosis against the background of pronounced microcirculatory disorders.The obtained results indicate the need for pre-nosological diagnostics of cardiovascular diseases and their prevention among miners working in harmful working conditions.

Morphological structure of rat epiphysis exposed to electromagnetic radiation from communication devices

Pineal gland is one of the most important components of homeostasis - the supporting system of the body. It participates in the launch of stress responses, restriction of their development, prevention of adverse effects on the body. There was proved an impact of electromagnetic radiation on the epiphysis. However, morphological changes in the epiphysis under exposure to electromagnetic radiation of modern communication devices are studied not sufficiently. For the time present the population is daily exposed to electromagnetic radiation, including local irradiation on the brain. These date determined the task of this research - the study of the structure of rat pineal gland under the exposure to electromagnetic radiation from personal computers and mobile phones. These date determined the task of this research - the study of the structure of rat pineal gland under the exposure to electromagnetic radiation from personal computers and mobile phones. Performed transmission electron microscopy revealed signs of degeneration of dark and light pinealocytes. These signs were manifested in the development of a complex of general and specific morphological changes. There was revealed the appearance of signs of aging and depletion transmission electron microscopy both in light and dark pinealocytes. These signs were manifested in the accumulation of lipofuscin granules and electron-dense "brain sand", the disappearance of nucleoli, cytoplasm vacuolization and mitochondrial cristae enlightenment.

Mild heat stress induces hormetic effects in protecting the primary culture of mouse prefrontal cerebrocortical neurons from neuropathological alterations

Hormesis is a dose response phenomenon of cells and organisms to various types of stressors. Mild stress stimulates prosurvival pathways and makes the cells adaptive to stressful conditions. It is a widely used fundamental dose-response phenomenon in many biomedical and toxicological sciences, radiation biology, health science etc. Mild heat stress is an easily applicable hormetic agent that exerts consistent results. In the present investigations mouse cerebrocortical prefrontal neurons from E17 mouse embryos were grown in the laboratory on poly-L-lysine coated glass cover slips. The cells from the mild heat stressed group were subjected to a hyperthermic stress of 38 °C for 30 min every alternate day (i.e. mild heat stress was repeated after 48 h) up to the sixth day. After completion of twenty four hours of the final i.e. third exposure of the mild heat stress, the neurons were fixed for the cytochemical studies of neurofibrillary tangles, senile plaques, lipofuscin granules and Nissl substance. There was highly significant decrease in the neuropathological alterations (viz. deposition of Neurofibrillary tangles, deposition of senile plaques, accumulation of Lipofuscin granules) in the neurons from the mild heat stressed group as compared to control. Moreover, the Nissl substance was significantly preserved in the mild heat stressed group as compared to control. The results indicate that the applied mild heat stress (38 °C for 30 min) exerts beneficial effects on the prefrontal cerebrocortical neurons by slowing down the neuropathological alterations, suggesting the hormetic effect of the mild heat stress.

Lysosomal and network alterations in human mucopolysaccharidosis type VII iPSC-derived neurons

Mucopolysaccharidosis type VII (MPS VII) is a lysosomal storage disease caused by deficient β-glucuronidase (β-gluc) activity. Significantly reduced β-gluc activity leads to accumulation of glycosaminoglycans (GAGs) in many tissues, including the brain. Numerous combinations of mutations in GUSB (the gene that codes for β-gluc) cause a range of neurological features that make disease prognosis and treatment challenging. Currently, there is little understanding of the molecular basis for MPS VII brain anomalies. To identify a neuronal phenotype that could be used to complement genetic analyses, we generated two iPSC clones derived from skin fibroblasts of an MPS VII patient. We found that MPS VII neurons exhibited reduced β-gluc activity and showed previously established disease-associated phenotypes, including GAGs accumulation, expanded endocytic compartments, accumulation of lipofuscin granules, more autophagosomes, and altered lysosome function. Addition of recombinant β-gluc to MPS VII neurons, which mimics enzyme replacement therapy, restored disease-associated phenotypes to levels similar to the healthy control. MPS VII neural cells cultured as 3D neurospheroids showed upregulated GFAP gene expression, which was associated with astrocyte reactivity, and downregulation of GABAergic neuron markers. Spontaneous calcium imaging analysis of MPS VII neurospheroids showed reduced neuronal activity and altered network connectivity in patient-derived neurospheroids compared to a healthy control. These results demonstrate the interplay between reduced β-gluc activity, GAG accumulation and alterations in neuronal activity, and provide a human experimental model for elucidating the bases of MPS VII-associated cognitive defects.

Mechanisms of Age-Dependent Loss of Dietary Restriction Protective Effects in Acute Kidney Injury.

Dietary restriction (DR) is one of the most efficient approaches ameliorating the severity of different pathological conditions including aging. We investigated the protective potential of short-term DR in the model of acute kidney injury (AKI) in young and old rats. In kidney tissue, the levels of autophagy and mitophagy were examined, and proliferative properties of renal cells obtained from rats of different age were compared. DR afforded a significant nephroprotection to ischemic kidneys of young rats. However, in old rats, DR did not provide such beneficial effect. On the assessment of the autophagy marker, the LC3 II/LC3 I ratio, and after staining the tissue with LysoTracker Green, we concluded that in old rats activity of the autophagic-lysosomal system decreased. Mitophagy, as assessed by the levels of PINK-1, was also deteriorated in old animals. Renal cells from old rats showed impaired proliferative capacity, a worse rate of recovery after ischemic injury, increased levels of oxidative stress, accumulation of lipofuscin granules and lower mitochondria membrane potential. The results suggest that the loss of DR benefits in old animals could be due to deterioration in the autophagy/mitophagy flux.

25.1 OLIGODENDROCYTE PATHOLOGY IN PREFRONTAL WHITE MATTER IN SCHIZOPHRENIA

BackgroundRecent neuroimaging studies have shown altered brain connectivity in patients with schizophrenia, associated with disturbed myelination in different fiber tracts and disruptions of white matter (WM) integrity, including prefrontal WM. We aimed to perform a qualitative and morphometric study of the ultrastructure of oligodendrocytes, myelin-forming cells, in prefrontal WM in schizophrenia and normal controls.MethodsWM of the prefrontal cortex (Brodmann’s area 10) was studied by transmission electron microscopy and morphometry. Size, volume density (Vv) and the number (N) of organelles in oligodendrocytes were estimated in 21 patients with schizophrenia and 20 normal matched controls. Pearson correlation analysis was performed to assess possible correlations between the parameters measured and age, post-mortem interval, neuroleptic treatment and duration of the disease. ANCOVA tests were used for group comparisons.ResultsQualitative study showed swelling, vacuolation, paucity of ribosomes and mitochondria and accumulation of lipofuscin granules in oligodendrocytes in schizophrenia as compared to controls. Morphometry detected lowered Vv and N of mitochondria and higher Vv and N of lipofuscin granules and vacuoles in oligodendrocytes in the schizophrenic group as compared to the control group (all p<0.01).DiscussionAltered metabolism of oligodendrocytes, previously reported reduced number of oligodendrocytes, disrupted myelin/axon integrity, damage and progressive degeneration of myelin sheaths in prefrontal WM in schizophrenia may lead to disturbances in myelination, deficiency of nerve impulses propagation and contribute to network dysfunctions in schizophrenia. Oligodendrocyte and myelin abnormalities may be a target to prevent or restore WM abnormalities and dysfunction of neuronal connectivity in schizophrenia.

Age-related adaptive responses of mitochondria of the retinal pigment epithelium to the everyday blue LED lighting.

The effect of everyday blue light (λ = 440-460 nm) on mitochondria of the retinal pigment epithelium of different age groups of Japanese quail was studied using electron microscopy, morphometric methods, and biochemical analysis. We have found a significant increase in the number of mitochondria, including those modified, mainly in young birds. In addition, cell metabolic activity increased in response to blue lighting. These changes are assumed to reflect an adaptive response of mitochondria aimed at neutralizing the phototoxic effect of blue light caused by accumulation of lipofuscin granules.

Dry age-related macular degeneration like pathology in aged 5XFAD mice: Ultrastructure and microarray analysis.

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. The two types of AMD are: dry and wet AMD. While laser-induced choroidal neovascularization has been used extensively in the studies of wet AMD, there is no established mouse model that fully recapitulates the cardinal features of dry AMD. A lack of appropriate mouse model for dry AMD has hampered the translational research on the pathogenesis of the disease and the development of therapeutic agents. We hypothesized that 5XFAD mice, an animal model for the study of Alzheimer’s disease, can be used as a mouse model for dry AMD with regard to the amyloid beta (Aβ) related pathology. In this study, the ultrastructure of the retinal pigment epithelium (RPE) of 5XFAD mice was analyzed using transmission electron microscopy. Of importance, the aged 5XFAD mice show ultrastructural changes in the RPE and Bruch’s membrane (BM) that are compatible with the cardinal features of human dry AMD, including a loss of apical microvilli and basal infolding of the RPE, increased BM thickness, basal laminar and linear deposits, and accumulation of lipofuscin granules and undigested photoreceptor outer segment-laden phagosomes. In microarray-based analysis, the RPE complex of the aged 5XFAD mice shows differential gene expression profiles consistent with dry AMD in the inflammation response, immune reaction pathway, and decreased retinol metabolism. Taken together, we suggest that aged 5XFAD mice can be used as a mouse model of dry AMD to study Aβ related pathology and develop a new therapeutic approaches.

Ultrastructural alterations of oligodendrocytes in prefrontal white matter in schizophrenia: A post-mortem morphometric study

ObjectiveNeuroimaging studies showed abnormalities in frontal white matter (WM) in schizophrenia that were associated with clinical symptoms. Previously, we reported ultrastructural alterations of myelinated fibers and reduction in the numerical density of oligodendrocytes in BA 10 WM in patients with schizophrenia. We aimed to perform a qualitative and morphometric study of the ultrastructure of oligodendrocytes in BA 10 WM in schizophrenia and in normal controls. MethodsThe study was performed using electron microscopy and morphometry. Size, volume density (Vv) and the number (N) of organelles of oligodendrocytes were estimated in 21 patients with schizophrenia and 20 normal controls. The data were examined using the Kolmogorov–Smirnov test for normality. Pearson correlation analysis was performed to assess possible correlations between the parameters measured and age, post-mortem interval, neuroleptic treatment and duration of the disease. Comparisons between the schizophrenia patients and controls were performed using ANCOVA tests. ResultsWe found oligodendrocyte swelling, vacuolation, paucity of ribosomes and mitochondria and accumulation of lipofuscin granules in schizophrenia as compared to controls. Morphometry detected a significant reduction in Vv and N of mitochondria and the increase in Vv and N of lipofuscin granules and vacuoles in oligodendrocytes in the schizophrenic group as compared to controls. ConclusionAlterations of oligodendrocytes in schizophrenia provide evidence for the disturbance of their energy, lipid and protein metabolism in prefrontal WM. Oligodendrocyte abnormalities might disturb axonal integrity and circuitry and contribute to the pathophysiology of schizophrenia.

Morphological Characteristics of the Hippocampus in OXYS and Wistar Rats during the Aging Process

Light and electron microscopy studies were performed to evaluate structural changes in the hippocampus in prematurely aging rats of the OXYS strain (n = 20) and Wistar rats (n = 20) as they aged. Light microscopy showed neurons with signs of chromatolysis in fields CA1 and CA3 and the dentate gyrus of the hippocampus, along with hyperchromic neurons, providing evidence that OXYS rats had signs of degeneration as early as age four months. By 18 months of age, structural changes developed in all areas of the hippocampus in OXYS rats. Ultramicroscopy studies at age four months identified that these animals showed signs of destruction of mitochondria and accumulation of lipofuscin granules; these changes progressed with age, such that animals aged 18 months were characterized by significant organelle destruction. The data obtained here provide evidence of more extensive age-related changes to neurons in OXYS rats than in Wistar rats.

Subcellular aging markers of retinal pigment epithelium in Japanese quail Coturnix japonica

Age-related changes of retinal pigment epithelium of the Japanese quail, which at present is a promising experimental model of accelerated aging, were studied by electron microscopy using morphometric analysis. It was established that, along with accumulation of lipofuscin granules and ultrastructural changes of the Bruch’s membrane, changes in the shape of nuclei and mitochondria (increase in the portion of ring-shaped and dumbbell-like mitochondria), decrease in the amount of myeloid bodies, and disorganization of basal infoldings are also aging markers of retinal pigment epithelium.

Imaging in vitreoretinal diagnostics

Imaging in vitreoretinal diagnostics

The changes of age-related molecules in the trophocytes and fat cells of queen honeybees (Apis mellifera)

Queen honeybees (Apis mellifera) have much longer lifespans than worker bees. Although the expression of age-related molecules in the trophocytes and fat cells of young and old workers have been determined, the expression of age-related molecules in queens is unknown. In this study, we examined the expression of age-related molecules in the trophocytes and fat cells of young and old queens. Molecular analyses detected no differences in telomerase activity or telomere lengths between trophocytes and fat cells from young and old queens, indicating that these cells do not divide in adulthood. Further assays showed that old queens has higher non-homogeneous cellular morphology, senescence-associated β-galactosidase (SA-β-Gal) activity, accumulation of lipofuscin granules, lipid peroxidation, and protein oxidation compared to young queens. These results demonstrate that age-related molecules can be used to evaluate aging in the trophocytes and fat cells of queens and to lay the foundation for further study of the mechanisms that delay cellular aging in the trophocytes and fat cells of queens.

Autofluorescence: new tool to follow dry eye AMD?

Abstract Purpose In the pathophysiolgy of dry (atrophic) age related macular degeneration (AMD) aging of the retinal pigment epithelium (RPE) plays a key role. Accumulation of lipofuscin granules in the RPE cells represents a common downstream pathogenetic pathway in AMD. Lipofuscin is derived from chemically modified residues of incompletely digested photoreceptor outer segment discs. Detection of lipofuscin in vivo is possible by using fundus autofluorescence (FAF) imaging. The clinical application and possible implications of autofluorescence imaging in dry AMD will be discussed. Methods When stimulated with light in the blue to green range, lipofuscin granules emit a characteristic yellow fluorescence. FAF imaging using a scanning laser ophthalmoscope allows visualization of the topographic distribution of lipofuscin over large retinal areas. Examples of FAF images will be presented to demonstrate various FAF patterns and to discuss the clinical significance of these findings. Results In areas of geographic atrophy FAF images show very low autofluorescence intensity. This is due to the loss of RPE cells including the lipofuscin granules. In the junctional zone between atrophic and normal retina, levels of increased autofluorescence intensity may occur due to excessive accumulation of lipofuscin in the RPE cells. Longitudinal observations further suggest that the extension of the total area with increased autofluorescence intensity surrounding atrophy at baseline has a strong positive correlation with atrophy progression rate over time. Conclusion FAF imaging is an important diagnostic tool to follow the progression of dry AMD and other degenerative macular diseases and should always be considered in cases were the status of the RPE is unknown.

Loss of leucine-rich repeat kinase 2 causes impairment of protein degradation pathways, accumulation of α-synuclein, and apoptotic cell death in aged mice

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of Parkinson's disease. LRRK2 is a large protein containing a small GTPase domain and a kinase domain, but its physiological role is unknown. To identify the normal function of LRRK2 in vivo, we generated two independent lines of germ-line deletion mice. The dopaminergic system of LRRK2(-/-) mice appears normal, and numbers of dopaminergic neurons and levels of striatal dopamine are unchanged. However, LRRK2(-/-) kidneys, which suffer the greatest loss of LRRK compared with other organs, develop striking accumulation and aggregation of alpha-synuclein and ubiquitinated proteins at 20 months of age. The autophagy-lysosomal pathway is also impaired in the absence of LRRK2, as indicated by accumulation of lipofuscin granules as well as altered levels of LC3-II and p62. Furthermore, loss of LRRK2 dramatically increases apoptotic cell death, inflammatory responses, and oxidative damage. Collectively, our findings show that LRRK2 plays an essential and unexpected role in the regulation of protein homeostasis during aging, and suggest that LRRK2 mutations may cause Parkinson's disease and cell death via impairment of protein degradation pathways, leading to alpha-synuclein accumulation and aggregation over time.

Interaction of pyridinium bis-retinoid (A2E) with bilayer lipid membranes

The accumulation of lipofuscin granules within the retinal pigment epithelium (RPE) cells is correlated with the progression of age-related macular degeneration. One of the fluorophores contained in lipofiscin granules is pyridinium bis-retinoid (A2E). To test its membrane–toxic effect, the interaction of A2E with bilayer lipid membranes (BLM) was studied. The incorporation of charged A2E molecules into the membranes has been detected as a change of either ζ-potential of multilayer liposomes or boundary potential of BLM. It was shown that the presence of up to 25 mol% of A2E did not destabilize the bilayers made of saturated phosphatidylcholine (PC). However, the destabilizing effect became very significant when BLM contained negatively charged lipids such as cardiolipin or phosphatidylserine. The electrical breakdown measurements revealed that the A2E-induced decrease of BLM stability was primarily associated with the growing probability of lipid pore formation. It was found from the measurements of boundary potential of BLM that exposure of A2E to light initiates its transformation into at least two products. One of them is epoxy-A2E, which, being hydrophilic, moves from the membrane into water solution. The other product is a non-identified hydrophobic substance. Illumination of A2E-containing BLM made from unsaturated PC by visible light caused the membrane damage presumably due to oxidation of these lipids by singlet oxygen generated by excited A2E molecules. However, this effect was very weak compared to the effect of known photosensitizers. The illumination of BLM with A2E also leads to the damage of gramicidin incorporated into the membrane, as was detected by measuring the conductance of channels formed by this peptide.

Stress response of two coral species in the Kavaratti atoll of the Lakshadweep Archipelago, India

Frequent occurrences of coral bleaching and the ensuing damage to coral reefs have generated interest in documenting stress responses that precede bleaching. The objective of this study was to assess and compare physiological changes in healthy, semi-bleached and totally bleached colonies of two coral species, Porites lutea and Acropora formosa, during a natural bleaching event in the Lakshadweep Archipelago in the Arabian Sea to determine the traits that will be useful in the diagnosis of coral health. In April 2002, three “health conditions” were observed as “appearing healthy,” “semi-bleached” and “bleached” specimens for two dominant and co-occurring coral species in these islands. Changes in the pigment composition, zooxanthellae density (ZD), mitotic index (MI) of zooxanthellae, RNA/DNA ratios and protein profile in the two coral species showing different levels of bleaching in the field were compared to address the hypothesis of no difference in health condition between species and bleaching status. The loss in chlorophyll (chl) a, chl c and ZD in the transitional stage of semi-bleaching in the branched coral A. formosa was 80, 75 and 80%, respectively. The losses were much less in the massive coral P. lutea, being 20, 50 and 25%, respectively. The decrease in zooxanthellar density and chl a was accompanied by an increased MI of zooxanthellae and RNA/DNA ratios in both the species. There was an increase in accumulation of lipofuscin granules in partially bleached P. lutea tissue, which is an indication of cellular senescence. Multivariate statistical analyses showed that colonies of P. lutea ranked in different health conditions differed significantly in chl a, chl c, ZD, RNA/DNA ratios, and protein concentrations, whereas in A. formosa chl a, chl c, chl a/c, phaeopigments and MI contributed to the variance between health conditions.

Glial activation and TNFR-I upregulation precedes motor dysfunction in the spinal cord of mnd mice.

Mice homozygous for the spontaneous motor neuron degeneration mutation (mnd) show at the age of 8 months a marked impairment of the motor function and accumulation of lipofuscin granules in the cytoplasm of almost all neurons of the central nervous system. We previously reported a significant increase in GFAP protein levels in the lumbar spinal cord homogenates by western blot analysis and upregulation of TNF, a proinflammatory cytokine, in the motor neurons of lumbar spinal cord of mnd mice, already in a presymptomatic stage (4 months of age). In the present study, using immunohistochemical analysis, we performed a time course in mnd mice (1, 4 and 9 months of age) evaluating the expression and the distribution of astroglial and microglial cells and the expression of both TNF receptors, TNFR-I and TNFR-II. We observed a marked increase in astroglial and microglial cells and in TNFR-I immunoreactivity already at the 4th month. Since motor neuron dysfunction occurs in mnd mice in the absence of evident loss of spinal motor neurons, the present results indicate that the activation of microglial cells and astrocytes is independent from neuronal degeneration. The role of TNF and TNFR-I on motor neurons is still to be demonstrated.

Electrophysiologic-structural correlations in chagasic aneurysms causing malignant arrhythmias

We studied the structure and ultrastructure of three chagasic aneurysms, the excision of which abolished malignant arrhythmias. Chronic recurrent ventricular tachycardia often occurs in patients with chagasic aneurysms, and ventricular mapping indicates that these arrhythmias originate in regions adjacent to those aneurysms. In our patients, ventricular tachycardia had been refractory to medical treatment. During surgery, epicardial and endocardial mapping showed abnormal potentials. Sutures were placed in the areas of resection, their sizes approximating those of earliest activation so that these sites could be identified. The myocardium showed chronic inflammatory reaction, myocytolysis and fibrosis. The presence of “islets” was common (normal, “early” damaged or “established” necrotic myocytes surrounded by fibrous tissue). The “early” lesions were predominant at the previously identified areas of arrhythmogenic activity. The ultrastructural studies showed hypertrophy of myocytes and partial or complete loss of myofibrils, swelling of mitochondria and disruption of mitochondrial cristae, accumulation of lipofuscin granules, and intracellular oedema. A most striking alteration was the thickening of the basement membranes of myocytes and vascular endothelial and smooth muscle cells. The interlaced fronts of respectively healthy (fast conducting) and “early” damaged (slow conducting) myocytes seen in serial sectioning produced an ideal configuration for reentry circuits. The final proof that the arrhythmias originated in these endocardial regions was their abolition by resection of the aneurysm.