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1.
Methods Mol Biol ; 2561: 63-85, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36399265

RESUMO

In this protocol, we describe the specific steps required to prepare human postmortem brain samples for ultrastructural microglial analysis. A detailed procedure is provided to improve the ultrastructural quality of the samples, using aldehyde fixatives followed by immunoperoxidase staining of allograft inflammatory factor 1 (AIF1, also known as IBA1), a marker of myeloid cells, and cluster of differentiation 68 (CD68), a marker of phagolysosomal activity. Additionally, we describe an osmium-thiocarbohydrazide-osmium (OTO) post-fixation method that preserves and increases the contrast of cellular membranes in human postmortem brain samples, as well as the steps necessary to acquire scanning electron microscopy (SEM) images of microglial cell bodies. In the last section, we cover the quantitative analysis of various microglial cytoplasmic organelles and their interactions with other parenchymal elements.


Assuntos
Encéfalo , Microglia , Humanos , Microglia/ultraestrutura , Microscopia Eletrônica de Varredura , Autopsia , Fixadores
2.
Ann Anat ; 245: 152006, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36183939

RESUMO

BACKGROUND: Cell-cell communication through extracellular vesicles (EVs) including exosomes, microvesicles and apoptotic bodies has been shown to be important in physiological homoeostasis as well as pathological processes such as atherosclerosis. However, while the cellular machinery controlling EV formation and composition has been studied during the past decade, less is known about the morphological process of their formation and release. METHODS: Using different electron microscopic approaches including transmission-, scanning-, immun-, and serial block face electron microscopy we studied the morphogenetic events of EV formation and release. We analysed the different steps of EV formation and release in cultured myocardial endothelial (MyEnd) and aortic endothelial (AoEnd) cell lines under serum starvation and under inflammatory conditions. RESULTS: We show that in a narrow time frame, the number of active cells and microvesicle (MV) producing cells increased in dependence of time spent in cultivation and additional stimulation by TNF-α. However, MV secretion was a highly heterogeneous process which couldn´t be seen in all cells cultivated under the same conditions. Release of MVs could be observed all over the cells' surface with no preferred release site. While no single specific microscopic approach applied was sufficient to provide a comprehensive analysis of EV biogenesis, we show that the limitations of one technique could be compensated by the qualities of the respective other applied techniques, thus enabling us to provide a detailed ultrastructural analysis of MV and exosome biogenesis. Surprisingly, exosome release in endothelial cells occurred via a yet undescribed process indicating that MVBs were incorporated into a novel distinct cellular compartment covered by fenestrated endothelium before exosome release. Lastly, we could show that TNF-α stimulation of AoEnd cells leads not only to the upregulation of CD44 in parental cells, but also to incorporation of CD44 into the membranes of generated MVs and exosomes. CONCLUSIONS: Taken together, our data contribute to a better understanding of biogenesis and release of EVs. We conclude that under inflammatory conditions, EVs can mediate the transfer of CD44 from endothelial cells to target cells at distant sites including vessel wall cells and this could be a mechanism by which MVs may change the and thus contribute to the development and progression of atherosclerotic lesions.


Assuntos
Aterosclerose , Exossomos , Vesículas Extracelulares , Humanos , Células Endoteliais , Fator de Necrose Tumoral alfa/análise , Fator de Necrose Tumoral alfa/metabolismo , Vesículas Extracelulares/metabolismo , Exossomos/química , Exossomos/metabolismo , Exossomos/ultraestrutura , Endotélio
3.
Ann Anat ; 245: 152001, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36195291

RESUMO

PURPOSE: To expand the routine of pathological diagnostics of surgical keratoplasty specimens via transmission electron microscopy. The target was to identify the best re-embedding method for optimal structural preservation of formalin fixed paraffin embedded (FFPE) corneal tissue re-embedded into resin for ultrastructural analysis. BASIC PROCEDURES: Bovine FFPE corneal tissue was re-embedded into resin with either a rapid osmium-free four-hour-method or a four-day-routine-method known from nephropathology, compared with primary resin embedded bovine corneal tissue. The analysis involved the ultrastructure of cytoplasm, the intercellular interfaces of superficial epithelial cells, deepest basal epithelial cells and corneal endothelial cells, cell matrix interfaces, Bowman layer, corneal stroma, its microfibril bundles and Descemet membrane. MAIN FINDINGS: The main observation was the equally reduced preservation status of re-embedded FFPE corneal tissue independent of the used re-embedding method. This extends to the intercellular contacts of superficial epithelial cells and the apical tight junctions of corneal endothelial cells. Hemidesmosomal cell matrix contacts showed less demarcation in re-embedded specimens. Cell matrix interfaces of Bowman layer and Descemet membrane were more clearly bordered in primary resin embedded than re-embedded tissue. In contrast, gap junctions in re-embedded tissue were detected in deepest basal epithelial cells and corneal endothelial cells with comparable preservation to primary resin embedding. Bowman layer, corneal stromal extracellular matrix, its microfibril bundles and Descemet membrane showed equal ultrastructural preservation in all evaluated methods. PRINCIPAL CONCLUSION: Corneal tissue can be successfully analysed with transmission electron microscopy after a rapid osmium-free four hour re-embedding procedure from FFPE material. A comparable morphology with primary resin embedded material can be obtained for gap junctions of deepest basal epithelial cells and corneal endothelial cells, further for Bowman layer, corneal stromal extracellular matrix, its microfibril bundles and Descemet membrane.


Assuntos
Córnea , Células Endoteliais , Bovinos , Animais , Córnea/patologia , Córnea/ultraestrutura , Substância Própria/ultraestrutura , Microscopia Eletrônica de Transmissão , Contagem de Células
4.
PLoS One ; 17(11): e0277616, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36378676

RESUMO

Woody cells, such as tracheids, fibers, vessels, rays etc., have unique structural characteristics such as nano-scale ultrastructure represented by multilayers, microfibril angle (MFA), micro-scale anatomical properties and spatial arrangement. Simultaneous evaluation of the above indices is very important for their adequate quantification and extracting the effects of external stimuli from them. However, it is difficult in general to achieve the above only by traditional methodologies. To overcome the above point, a new methodological framework combining polarization optical microscopy, fluorescence microscopy, and image segmentation is proposed. The framework was tested to a model softwood species, Chamaecyparis obtusa for characterizing intra-annual transition of MFA and tracheid morphology in a radial file unit. According our result, this framework successfully traced the both characteristics tracheid by tracheid and revealed the high correlation (|r| > 0.5) between S2 microfibril angles and tracheidal morphology (lumen radial diameter, tangential wall thickness and cell wall occupancy). In addition, radial file based evaluation firstly revealed their complex transitional behavior in transition and latewood. The proposed framework has great potential as one of the unique tools to provide detailed insights into heterogeneity of intra and inter-cells in the wide field of view through the simultaneous evaluation of cells' ultrastructure and morphological properties.


Assuntos
Chamaecyparis , Microfibrilas , Microscopia , Madeira , Parede Celular/ultraestrutura
5.
Sci Rep ; 12(1): 18517, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-36323867

RESUMO

In insects, females can keep sperm capable of fertilisation over a long period with the help of the spermatheca. The effectiveness of storing fertile sperm is expected to reflect in the reproductive strategy and, thus, the morphology of the involved organs. In this work, we focused on the relationship between reproduction and morphology in the haplodiploid Thysanoptera, especially if a loss of these traits occurs under thelytoky. The spermathecal morphology and the fate of stored spermatozoa were studied by microscopic techniques (high-resolution x-ray computed tomography and transmission electron microscopy) in three species with different reproductive modes and lifestyles (Suocerathrips linguis, Echinothrips americanus, Hercinothrips femoralis). Mating experiments were conducted to analyse the use of the transferred sperm in the thelytokous H. femoralis. Results show that the spermathecae are relatively simple, which can be explained by the availability of sperm and the short lifespan of the females. However, the spermatheca in H. femoralis seems to be vestigial compared to the arrhenotokous species and females do not use sperm for fertilisation. No substantial change was observed in the structure of spermatozoa, despite an enlargement of the sperm organelles being measured during storage in all three species. The results of this work demonstrate differences in the morphology of the spermatheca, especially concerning the reproduction mode, promoting the understanding of the complex interaction between morphology and behaviour.


Assuntos
Sêmen , Espermatozoides , Animais , Feminino , Masculino , Espermatozoides/ultraestrutura , Reprodução , Fertilidade , Insetos
6.
Science ; 378(6619): 500-504, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36378967

RESUMO

A comprehensive description of how neurons and entire brain regions are interconnected is fundamental for a mechanistic understanding of brain function and dysfunction. Neuroimaging has shaped the way to approaching the human brain's connectivity on the basis of diffusion magnetic resonance imaging and tractography. At the same time, polarization, fluorescence, and electron microscopy became available, which pushed spatial resolution and sensitivity to the axonal or even to the synaptic level. New methods are mandatory to inform and constrain whole-brain tractography by regional, high-resolution connectivity data and local fiber geometry. Machine learning and simulation can provide predictions where experimental data are missing. Future interoperable atlases require new concepts, including high-resolution templates and directionality, to represent variants of tractography solutions and estimates of their accuracy.


Assuntos
Encéfalo , Conectoma , Neuroimagem , Humanos , Encéfalo/ultraestrutura , Conectoma/métodos , Imagem de Difusão por Ressonância Magnética , Neuroimagem/métodos , Neurônios
7.
Science ; 378(6619): eadc9020, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36378959

RESUMO

Astrocytes, a type of glia, are abundant and morphologically complex cells. Here, we report astrocyte molecular profiles, diversity, and morphology across the mouse central nervous system (CNS). We identified shared and region-specific astrocytic genes and functions and explored the cellular origins of their regional diversity. We identified gene networks correlated with astrocyte morphology, several of which unexpectedly contained Alzheimer's disease (AD) risk genes. CRISPR/Cas9-mediated reduction of candidate genes reduced astrocyte morphological complexity and resulted in cognitive deficits. The same genes were down-regulated in human AD, in an AD mouse model that displayed reduced astrocyte morphology, and in other human brain disorders. We thus provide comprehensive molecular data on astrocyte diversity and mechanisms across the CNS and on the molecular basis of astrocyte morphology in health and disease.


Assuntos
Doença de Alzheimer , Astrócitos , Sistema Nervoso Central , Transcriptoma , Animais , Humanos , Camundongos , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Astrócitos/classificação , Astrócitos/metabolismo , Astrócitos/ultraestrutura , Modelos Animais de Doenças , Sistema Nervoso Central/citologia , Sistema Nervoso Central/metabolismo
8.
Science ; 378(6619): 505-510, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36378968

RESUMO

There is more to brain connections than the mere transfer of signals between brain regions. Behavior and cognition emerge through cortical area interaction. This requires integration between local and distant areas orchestrated by densely connected networks. Brain connections determine the brain's functional organization. The imaging of connections in the living brain has provided an opportunity to identify the driving factors behind the neurobiology of cognition. Connectivity differences between species and among humans have furthered the understanding of brain evolution and of diverging cognitive profiles. Brain pathologies amplify this variability through disconnections and, consequently, the disintegration of cognitive functions. The prediction of long-term symptoms is now preferentially based on brain disconnections. This paradigm shift will reshape our brain maps and challenge current brain models.


Assuntos
Encéfalo , Cognição , Conectoma , Rede Nervosa , Humanos , Encéfalo/fisiologia , Encéfalo/ultraestrutura , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/ultraestrutura
9.
Science ; 378(6619): 486-487, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36378965
10.
Science ; 378(6619): 488-492, 2022 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-36378966

RESUMO

Detailed knowledge about the neural connections among regions of the brain is key for advancing our understanding of normal brain function and changes that occur with aging and disease. Researchers use a range of experimental techniques to map connections at different levels of granularity in rodent animal models, but the results are often challenging to compare and integrate. Three-dimensional reference atlases of the brain provide new opportunities for cumulating, integrating, and reinterpreting research findings across studies. Here, we review approaches for integrating data describing neural connections and other modalities in rodent brain atlases and discuss how atlas-based workflows can facilitate brainwide analyses of neural network organization in relation to other facets of neuroarchitecture.


Assuntos
Atlas como Assunto , Mapeamento Encefálico , Encéfalo , Animais , Envelhecimento , Encéfalo/ultraestrutura
11.
Medicina (Kaunas) ; 58(11)2022 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-36363464

RESUMO

Background and Objectives: The post-mortem diagnosis of hypothermia is challenging in forensics. The aim of our study was to detect the kidney and heart histopathological changes that occurred in a group of hypothermia-related fatalities. Materials and Methods: The cohort included 107 cases identified in the database of our department between 2007 and 2021, which have been associated with extreme cold stress. Demographic and clinicopathological data were collected from the medico-legal reports. Archived tissue samples were evaluated to identify the histopathological features, in routine haematoxylin-eosin (H&E), Periodic acid-Schiff (PAS), and Masson's trichrome stainings, while cardiac sirtuin1 (SIRT1) and renal ubiquitin (Ub) immunostaining have been performed. Results: The majority of cases exposed to low temperatures were males (76%) from rural regions (68.2%) during the cold season. Paradoxical undressing was documented in 9.3% of cases. The common comorbidities included alcoholism (50.5%), neuropsychiatric diseases (10.3%), diabetes mellitus (3.7%), and lung tuberculosis (4.7%). The microscopic heart exam revealed areas of myocardial degeneration (100%), contraction bands (95.3%), fatty change (13.1%) and focal wavy contractile myocardial cells. Basal vacuolisation of renal tubular epithelial cells (Armanni-Ebstein lesions) (21.5%), focal tubular necrosis (7.5%), tubular renal cysts (7.5%), interstitial haemorrhages (5.6%), diabetic kidney disease (3.7%), background benign nephroangiosclerosis (42.1%), variable thickening of tubules and corpuscles basement membranes, capsular space amorphous material, and intratubular casts were identified in kidney tissue samples. Myocardial cells displayed SIRT1 weak expression, with a loss of immunopositivity correlated with areas with contraction bands, while a variable Ub expression was observed in renal corpuscles capsules, proximal, distal, and collecting renal tubules, Henle's loops, urothelium, and intratubular casts. Conclusions: In the context of the current concept that death associated with hypothermia is still a diagnosis of exclusion, our findings suggest that the microscopic exam provides relevant data that support the diagnosis of hypothermia-related fatalities in appropriate circumstances of death. A deeper insight into the histopathologic findings in hypothermic patients may lead to new therapeutic approaches in these cases.


Assuntos
Hipotermia , Masculino , Humanos , Feminino , Sirtuína 1 , Rim/patologia , Túbulos Renais/patologia , Túbulos Renais/ultraestrutura , Miocárdio/patologia
12.
Sci Rep ; 12(1): 20172, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36424494

RESUMO

Insect antennae are astonishingly versatile and have multiple sensory modalities. Audition, detection of airflow, and graviception are combined in the antennal chordotonal organs. The miniaturization of these complex multisensory organs has never been investigated. Here we present a comprehensive study of the structure and scaling of the antennal chordotonal organs of the extremely miniaturized parasitoid wasp Megaphragma viggianii based on 3D electron microscopy. Johnston's organ of M. viggianii consists of 19 amphinematic scolopidia (95 cells); the central organ consists of five scolopidia (20 cells). Plesiomorphic composition includes one accessory cell per scolopidium, but in M. viggianii this ratio is only 0.3. Scolopale rods in Johnston's organ have a unique structure. Allometric analyses demonstrate the effects of scaling on the antennal chordotonal organs in insects. Our results not only shed light on the universal principles of miniaturization of sense organs, but also provide context for future interpretation of the M. viggianii connectome.


Assuntos
Antenas de Artrópodes , Mecanorreceptores , Animais , Mecanorreceptores/ultraestrutura , Órgãos dos Sentidos/ultraestrutura , Microscopia Eletrônica , Insetos
13.
An Acad Bras Cienc ; 94(suppl 3): e20211145, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36417605

RESUMO

The spore morphology and wall ultrastructure of 12 species of Ctenitis from Southern Cone of America were studied using light microscope, scanning and transmission electron microscope. The study was carried out with herbarium material from Argentine and Brazilian institutions. Equatorial diameters, polar diameters and laesura length were measured. The spores are monolete with echinate or folded ornamentation. In the echinate type, the spines are conical, with broad base and attenuate apex. In the rugate type, the folds are inflated, linear, sinuous, subglobose or handle-shape. The perispore surface is scabrate, rugulate, microverrucose or psilate. Stratification and ultrastructure in the species analyzed are very similar. The exospore is smooth and two-layered in section. Simple and branched channels are observed mainly in the outer exospore. The perispore is composed of two layers, the inner one forms the ornamentation and the outer covers all the outer and inner surfaces. Immature spores were found in all samples of C. fenestralis. The characteristics of the studied spores like macro-ornamentation, color and fold length provide relevant information to differentiate some species or groups of species within the genus.


Assuntos
Dryopteridaceae , Esporos/ultraestrutura , Microscopia , Brasil
14.
BMC Bioinformatics ; 23(1): 453, 2022 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-36316652

RESUMO

BACKGROUND: Nanoscale connectomics, which aims to map the fine connections between neurons with synaptic-level detail, has attracted increasing attention in recent years. Currently, the automated reconstruction algorithms in electron microscope volumes are in great demand. Most existing reconstruction methodologies for cellular and subcellular structures are independent, and exploring the inter-relationships between structures will contribute to image analysis. The primary goal of this research is to construct a joint optimization framework to improve the accuracy and efficiency of neural structure reconstruction algorithms. RESULTS: In this investigation, we introduce the concept of connectivity consensus between cellular and subcellular structures based on biological domain knowledge for neural structure agglomeration problems. We propose a joint graph partitioning model for solving ultrastructural and neuronal connections to overcome the limitations of connectivity cues at different levels. The advantage of the optimization model is the simultaneous reconstruction of multiple structures in one optimization step. The experimental results on several public datasets demonstrate that the joint optimization model outperforms existing hierarchical agglomeration algorithms. CONCLUSIONS: We present a joint optimization model by connectivity consensus to solve the neural structure agglomeration problem and demonstrate its superiority to existing methods. The intention of introducing connectivity consensus between different structures is to build a suitable optimization model that makes the reconstruction goals more consistent with biological plausible and domain knowledge. This idea can inspire other researchers to optimize existing reconstruction algorithms and other areas of biological data analysis.


Assuntos
Elétrons , Processamento de Imagem Assistida por Computador , Consenso , Processamento de Imagem Assistida por Computador/métodos , Neurônios/ultraestrutura , Algoritmos
15.
Front Endocrinol (Lausanne) ; 13: 984081, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36339398

RESUMO

The leopard coral trout generally exhibited numerous round, minute blue spots covering its head (about the size of nostril) and body (except ventral side). This is a characteristic that distinguishes them from similar species. Recently, however, we found the leopard coral trout with black spots. Here, the distribution and ultrastructure of chromatophores in the blue and black spots were investigated with light and transmission electron microscopies. The results showed that in the blue spots, two types of chromatophores are present in the dermis, with the light-reflecting iridophores located in the upper layer and the aggregated light-absorbing melanophores in the lower layer. Black spots have a similar chromatophore composition, except that the melanosomes within the melanophores disperse their dendritic processes to encircle the iridophores. Interestingly, after the treatment of forskolin, a potent adenylate cyclase activator, the blue spots on the body surface turned black. On the other hand, using the skin preparations in vitro, the electrical stimulation and norepinephrine treatment returned the spots to blue color again, indicating the sympathetic nerves were involved in regulating the coloration of blue spots. Taken together, our results revealed that the blue spots of the leopard coral trout can change color to black and vice versa, resulting from the differences in the distribution of melanosomes, which enriches our understanding of the body color and color changes of fishes.


Assuntos
Antozoários , Bass , Cromatóforos , Panthera , Animais , Cromatóforos/ultraestrutura , Truta
16.
Molecules ; 27(22)2022 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-36431808

RESUMO

Diabetes mellitus is one of the most prevalent metabolic disorders characterized by hyperglycemia due to impaired glucose metabolism. Overproduction of free radicals due to chronic hyperglycemia may cause oxidative stress, which delays wound healing in diabetic conditions. For people with diabetes, this impeded wound healing is one of the predominant reasons for mortality and morbidity. The study aimed to develop an Ocimum sanctum leaf extract-mediated green synthesis of titanium dioxide (TiO2) nanoparticles (NPs) and further incorporate them into 2% chitosan (CS) gel for diabetic wound healing. UV-visible spectrum analysis recorded the sharp peak at 235 and 320 nm, and this was the preliminary sign for the biosynthesis of TiO2 NPs. The FTIR analysis was used to perform a qualitative validation of the biosynthesized TiO2 nanoparticles. XRD analysis indicated the crystallinity of TiO2 NPs in anatase form. Microscopic investigation revealed that TiO2 NPs were spherical and polygonal in shape, with sizes ranging from 75 to 123 nm. The EDX analysis of green synthesized NPs showed the presence of TiO2 NPs, demonstrating the peak of titanium ion and oxygen. The hydrodynamic diameter and polydispersity index (PDI) of the TiO2 NPs were found to be 130.3 nm and 0.237, respectively. The developed TiO2 NPs containing CS gel exhibited the desired thixotropic properties with pseudoplastic behavior. In vivo wound healing studies and histopathological investigations of healed wounds demonstrated the excellent wound-healing efficacy of TiO2 NPs containing CS gel in diabetic rats.


Assuntos
Diabetes Mellitus Experimental , Hiperglicemia , Nanopartículas , Óleos Voláteis , Ratos , Animais , Titânio/farmacologia , Ocimum sanctum/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Nanopartículas/ultraestrutura , Cicatrização , Extratos Vegetais/farmacologia , Extratos Vegetais/metabolismo
17.
PLoS One ; 17(10): e0273505, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36190996

RESUMO

Calcareous red algae are foundation species and ecosystem engineers with a global distribution. The principles governing their calcification pathways are still debated and the morphological characters are frequently unreliable for species segregation, as shown by molecular genetics. The recent description of the new species Lithophyllum pseudoracemus, previously undetected and morphologically confused with Lithophyllum racemus, offered a challenging opportunity to test the effectiveness of microanatomy and ultrastructural calcification traits as tools for the identification of these two species, for integrative taxonomy. High resolution SEM images of molecularly identified samples showed that the different size of the perithallial cells and the features of the asexual conceptacle chambers may contribute to the separation of the two species. The two species share the same crystallite morphology in the primary and secondary cell-wall calcification, as previously described in other species belonging to the same clade. However, the perithallial secondary calcification was significantly thicker in L. racemus than in L. pseudoracemus. We described a granular calcified layer in the innermost part of the cell wall, as a putative precursor phase in the biomineralization and formation of the secondary calcification. The hypothesis of different pathways for the formation of the primary and secondary calcification is supported by the observed cell elongation associated with thicker and higher Mg/Ca primary calcification, the inverse correlation of primary and secondary calcification thickness, and the absence of primary calcification in the newly formed wall cutting off an epithallial cell from the meristem.


Assuntos
Biomineralização , Rodófitas , Calcificação Fisiológica , Ecossistema , Fenótipo , Rodófitas/ultraestrutura
18.
Philos Trans R Soc Lond B Biol Sci ; 377(1864): 20210323, 2022 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-36189807

RESUMO

Diabetic cardiomyopathy is a leading cause of heart failure in diabetes. At the cellular level, diabetic cardiomyopathy leads to altered mitochondrial energy metabolism and cardiomyocyte ultrastructure. We combined electron microscopy (EM) and computational modelling to understand the impact of diabetes-induced ultrastructural changes on cardiac bioenergetics. We collected transverse micrographs of multiple control and type I diabetic rat cardiomyocytes using EM. Micrographs were converted to finite-element meshes, and bioenergetics was simulated over them using a biophysical model. The simulations also incorporated depressed mitochondrial capacity for oxidative phosphorylation (OXPHOS) and creatine kinase (CK) reactions to simulate diabetes-induced mitochondrial dysfunction. Analysis of micrographs revealed a 14% decline in mitochondrial area fraction in diabetic cardiomyocytes, and an irregular arrangement of mitochondria and myofibrils. Simulations predicted that this irregular arrangement, coupled with the depressed activity of mitochondrial CK enzymes, leads to large spatial variation in adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio profile of diabetic cardiomyocytes. However, when spatially averaged, myofibrillar ADP/ATP ratios of a cardiomyocyte do not change with diabetes. Instead, average concentration of inorganic phosphate rises by 40% owing to lower mitochondrial area fraction and dysfunction in OXPHOS. These simulations indicate that a disorganized cellular ultrastructure negatively impacts metabolite transport in diabetic cardiomyopathy. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.


Assuntos
Diabetes Mellitus , Cardiomiopatias Diabéticas , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Creatina Quinase/metabolismo , Diabetes Mellitus/metabolismo , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/metabolismo , Metabolismo Energético , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/ultraestrutura , Miócitos Cardíacos/metabolismo , Fosfatos/metabolismo , Ratos
19.
Philos Trans R Soc Lond B Biol Sci ; 377(1864): 20210332, 2022 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-36189815

RESUMO

Bird cardiomyocytes are long, thin and lack transverse (t)-tubules, which is akin to the cardiomyocyte morphology of ectothermic non-avian reptiles, who are typified by low maximum heart rates and low pressure development. However, birds can achieve greater contractile rates and developed pressures than mammals, whose wide cardiomyocytes contain a dense t-tubular network allowing for uniform excitation-contraction coupling and strong contractile force. To address this apparent paradox, this paper functionally links recent electrophysiological studies on bird cardiomyocytes with decades of ultrastructure measurements. It shows that it is the strong transsarcolemmal Ca2+ influx via the L-type Ca2+ current (ICaL) and the high gain of Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR), coupled with an internal SR Ca2+ release relay system, that facilitates the strong fast contractions in the long thin bird cardiomyocytes, without the need for t-tubules. The maintenance of an elongated myocyte morphology following the post-hatch transition from ectothermy to endothermy in birds is discussed in relation to cardiac load, myocyte ploidy, and cardiac regeneration potential in adult cardiomyocytes. Overall, the paper shows how little we know about cellular Ca2+ dynamics in the bird heart and suggests how increased research efforts in this area would provide vital information in our quest to understand the role of myocyte architecture in the evolution of the vertebrate heart. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'. Please see glossary at the end of the paper for definitions of specialized terms.


Assuntos
Cálcio , Miócitos Cardíacos , Animais , Aves , Mamíferos , Retículo Sarcoplasmático/fisiologia , Retículo Sarcoplasmático/ultraestrutura , Vertebrados
20.
J Psychiatr Res ; 155: 401-409, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36182770

RESUMO

BACKGROUND: According to previous studies, myelin damage may be involved in the occurrence of depression. However, to date, no study has quantitatively investigated the changes in myelinated fibers and myelin sheaths in the hippocampal formation (HF) and hippocampal subfields in the context of depression. METHODS: Male Sprague-Dawley (SD) rats (aged 4-5 weeks) were evenly divided into the control group and chronic unpredictable stress (CUS) group. Behavioral tests were performed, and then changes in myelinated fibers and myelin ultrastructure in hippocampal subfields in depression model rats were investigated using modern stereological methods and transmission electron microscopy techniques. RESULTS: After a four-week CUS protocol, CUS rats showed depressive-like and anxiety-like behaviors. The total length and total volume of myelinated fibers were reduced in the CA1 region and DG in the CUS group compared with the control group. The total volumes of myelin sheaths and axons in the CA1 region but not in the DG were significantly lower in the CUS group than in the control group. The decrease in the total length of myelinated nerve fibers in the CA1 region in CUS rats was mainly due to a decrease in the length of myelinated fibers with a myelin sheath thickness of 0.15 µm-0.20 µm. LIMITATIONS: The exact relationship between the degeneration of myelin sheaths and depression-like, anxiety-like behaviors needs to be further investigated. CONCLUSIONS: CUS induces depression- and anxiety-like behaviors, and the demyelination in the CA1 region induced by 4 weeks of CUS might be an important structural basis for these behaviors.


Assuntos
Depressão , Bainha de Mielina , Animais , Cobre , Depressão/etiologia , Modelos Animais de Doenças , Hipocampo , Masculino , Bainha de Mielina/ultraestrutura , Ratos , Ratos Sprague-Dawley , Estresse Psicológico/complicações
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