Toxicity of engineered nanomaterials with different physicochemical properties and the role of protein corona on cellular uptake and intrinsic ROS production.

The Organisation for Economic Co-operation and Development has listed thirteen engineered nanomaterials (ENM) in order to investigate their toxicity on human health. Silicon dioxide (SiO2) and titanium dioxide (TiO2) are included on that list and we added indium tin oxide (ITO) nanoparticles (NPs) to our study, which is not listed on OECD suggested ENM to be investigated, however ITO NPs has a high potential of industrial production. We evaluate the physicochemical properties of SiO2 NPs (10-20 nm), TiO2 nanofibers (NFs; 3 µm length) and ITO NPs (<50 nm) and the impact of protein-corona formation on cell internalization. Then, we evaluated the toxicity of uncoated ENM on human lung epithelial cells exposed to 10 and 50 µg/cm2 for 24 h. TiO2 NFs showed the highest capability to adsorb proteins onto the particle surface followed by SiO2 NPs and ITO NPs after acellular incubation with fetal bovine serum. The protein adsorption had no impact on Alizarin Red S conjugation, intrinsic properties for reactive oxygen (ROS) formation or cell uptake for all types of ENM. Moreover, TiO2 NFs induced highest cell alterations in human lung epithelial cells exposed to 10 and 50 µg/cm2 while ITO NPs induced moderated cytotoxicity and SiO2 NPs caused even lower cytotoxicity under the same conditions. DNA, proteins and lipids were mainly affected by TiO2 NFs followed by SiO2 NPs with toxic effects in protein and lipids while limited variations were detected after exposure to ITO NPs on spectra analyzed by Fourier Transform Infrared Spectroscopy.

The MPO system participates actively in the formation of an oxidative environment produced by neutrophils and activates the antioxidant mechanism of Naegleria fowleri.

Naegleria fowleri produces a fatal disease called primary amebic meningoencephalitis (PAM), which is characterized by an extensive inflammatory reaction in the CNS. It is known that the immune response is orchestrated mainly by neutrophils, which activate several defense mechanisms in the host, including phagocytosis, the release of different enzymes such as myeloperoxidase (MPO), and the production of neutrophil extracellular traps. However, the mechanisms by which amoebas evade the neutrophil response are still unknown. In this study, we analyzed the ability of N. fowleri to respond to the stress exerted by MPO. Interestingly, after the interaction of trophozoites with neutrophils, the amoeba viability was not altered; however, ultrastructural changes were observed. To analyze the influence of MPO against N. fowleri and its participation in free radical production, we evaluated its enzymatic activity, expression, and localization with and without the specific 4-aminobenzoic acid hydrazide inhibitor. The production of oxidizing molecules is the principal mechanism used by neutrophils to eliminate pathogens. In this context, we demonstrated an increase in the production of NO, superoxide anion, and reactive oxygen species; in addition, the overexpression of several antioxidant enzymes present in the trophozoites was quantified. The findings strongly suggest that N. fowleri possesses antioxidant machinery that is activated in response to an oxidative environment, allowing it to evade the neutrophil-mediated immune response, which may contribute to the establishment of PAM.

Aging and chromatoid body assembly: Are these two physiological events linked?

The chromatoid body is a cytoplasmic male germ cell structure that plays a role in the regulation of mRNA transcription during spermatogenesis. A proteomic analysis of this structure has identified the presence of its classic molecular markers (MVH and MIWI), as well as a significant number of transient proteins. Circadian locomotor output cycles protein kaput (CLOCK) and brain and muscle ARNT-like 1 (BMAL1), which are molecular components of the circadian clock, are likely located in the chromatoid body in a transient fashion. This study sought to determine whether aging produces morphological changes in the chromatoid bodies of round spermatids similar to those previously observed in BMAL1 knockout mice. A sample of 30 male mice was divided into three groups: juvenile mice (45 days old), adult mice (120 days old), and old mice (+180 days old). Aging was confirmed by viability and sperm count analyses and testosterone dosage. Squash slides prepared with fragments of seminiferous tubules were immunostained for MVH, MIWI, BMAL1, and CLOCK detection. In juvenile and adult specimens, single round chromatoid bodies were observed using MVH/BMAL1 and MIWI/CLOCK immunostaining. In old specimens, many chromatoid bodies displayed changes in number and morphology, as well as an increase in the interactions between MVH and BMAL1; MIWI and CLOCK. Changes in chromatoid body morphology increased interactions between the proteins analyzed herein, and decreased amounts of these proteins in seminiferous tubules of older mice may indicate that aging influences the assembly and physiology of chromatoid bodies, which may, in turn, affect fertility. Impact statement The results discussed in this paper indicate that aging compromises the structure and physiology of chromatoid bodies (CBs) in post-meiotic male cells. Since CB is a fundamental structure for the differentiation of the mature male germ cell it is possible that this imbalance in CB physiology may play a role in the reduction of fertility in older men. It is important to note that not only the classic CB markers (such as the MIWI and MVH proteins) were used to showcase the structural changes in the CBs but also the main components of circadian cycle control (the CLOCK and BMAL1 proteins), indicating that the reduction of circadian control in aged males may contribute to these changes in CBs as well. Therefore, it is intriguing to evaluate the hypothesis that controlling these physiological/structural changes in CBs may be a way of delaying the effects of aging in males.

Kinetics of human sperm acrosomal exocytosis.

The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.

O programa de assistência pré-natal nos Cuidados de Saúde Primários em Portugal: uma reflexão / The prenatal care program in Primary Care in Portugal: a reflection / El programa de vigilancia prenatal en la Atención Primaria en Portugal: una reflexión

A melhoria da qualidade dos cuidados prestados à grávida e ao recém-nascido é uma das áreas de intervenção prioritária do Plano Nacional de Saúde. Embora se reconheça que as medidas introduzidas nos últimos anos têm contribuído para diminuir os valores da mortalidade materna e perinatal, é necessário referir, também, que continuam a ocorrer gravidezes não planeadas que, não raras vezes, resultam do início tardio, ou mesmo da ausência, da assistência pré-natal. Neste artigo, procuramos refletir sobre a assistência pré-natal no contexto de saúde reprodutiva, de forma a constituir um contributo para os enfermeiros que prestam uma assistência integral e humanizada às grávidas e às suas famílias. Concluímos que a assistência pré-natal engloba um conjunto de cuidados específicos dirigidos a um grupo vulnerável, constituindo uma área muito importante na avaliação dos cuidados de saúde primários.

The quality improvement of care provided to the pregnant women and newborn is one of the priority areas for intervention of the National Health Plan. While acknowledging that the measures introduced in recent years have contributed to lower the values of maternal and perinatal mortality, it should also be mentioned that unplanned pregnancies continue to occur, and that they often result in a delayed or absent prenatal surveillance. In this paper, we seek to reflect on the prenatal surveillance program under Primary Health Care relating to quality of health care provided in the context of reproductive health. We concluded that prenatal surveillance includes a set of specific care services targeted at a vulnerable group, constituting an important and susceptible area of evaluation in primary care.

Mejorar la calidad de la atención a embarazada y recién nacido es una de las áreas prioritarias de intervención del plan nacional de salud. Aunque se reconoce que las medidas adoptadas en los últimos años han contribuido a reducir los valores de la mortalidad materna y perinatal, es necesario mencionar, también, que embarazos no planificados siguen produciéndose a menudo resultado de la aparición, o incluso ausencia, de vigilancia prenatal. En este artículo, reflexionamos sobre el programa de vigilancia prenatal en el marco de la atención primaria de salud, vinculándola con la calidad de la atención de la salud en el contexto de la salud reproductiva. Concluimos que la vigilancia prenatal comprende un conjunto de cuidados específicos dirigidos a un grupo vulnerable, lo que constituye un área sensible y evaluación importante en atención primaria.

Pigment granule translocation in red ovarian chromatophores from the palaemonid shrimp Macrobrachium olfersi (Weigmann, 1836): functional roles for the cytoskeleton and its molecular motors.

The binding of red pigment concentrating hormone (RPCH) to membrane receptors in crustacean chromatophores triggers Ca²âº/cGMP signaling cascades that activate cytoskeletal motors, driving pigment granule translocation. We investigate the distributions of microfilaments and microtubules and their associated molecular motors, myosin and dynein, by confocal and transmission electron microscopy, evaluating a functional role for the cytoskeleton in pigment translocation using inhibitors of polymer turnover and motor activity in vitro. Microtubules occupy the chromatophore cell extensions whether the pigment granules are aggregated or dispersed. The inhibition of microtubule turnover by taxol induces pigment aggregation and inhibits re-dispersion. Phalloidin-FITC actin labeling, together with tannic acid fixation and ultrastructural analysis, reveals that microfilaments form networks associated with the pigment granules. Actin polymerization induced by jasplaquinolide strongly inhibits RPCH-induced aggregation, causes spontaneous pigment dispersion, and inhibits pigment re-dispersion. Inhibition of actin polymerization by latrunculin-A completely impedes pigment aggregation and re-dispersion. Confocal immunocytochemistry shows that non-muscle myosin II (NMMII) co-localizes mainly with pigment granules while blebbistatin inhibition of NMMII strongly reduces the RPCH response, also inducing spontaneous pigment dispersion. Myosin II and dynein also co-localize with the pigment granules. Inhibition of dynein ATPase by erythro-9-(2-hydroxy-3-nonyl) adenine induces aggregation, inhibits RPCH-triggered aggregation, and inhibits re-dispersion. Granule aggregation and dispersion depend mainly on microfilament integrity although microtubules may be involved. Both cytoskeletal polymers are functional only when subunit turnover is active. Myosin and dynein may be the molecular motors that drive pigment aggregation. These mechanisms of granule translocation in crustacean chromatophores share various features with those of vertebrate pigment cells.

Evaluation of the mechanical damage on wheat starch granules by SEM, ESEM, AFM and texture image analysis.

The effect of mechanical damage on wheat starch granules surface, at a microstructural level, was investigated by scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM), and image textural analysis. The SEM and ESEM images of the native sample showed that the starch granules had smooth, flat surfaces and smooth edges. The samples with higher damaged starch content exhibited granular distortion, irregularity and less uniformity. The fractal dimension of contour parameter increased with mechanical damage, indicating that the surface irregularities quantitatively increased due to the damage. The surfaces of damaged granules showed depressions of different shapes and sizes. The roughness parameters and fractal dimension of the surface increased as a result of the mechanical damage. The surface of damaged granules showed higher entropy and lower homogeneity values when damaged starch increased. The results indicated that the mechanical process caused structural modifications at nano level.

Ultrastructural characterization of the hemocytes of Lasiodora sp. (Koch, 1850) (Araneae: Theraphosidae).

This paper is the first descriptive review of hemolymph cell types in the circulation of the tarantula spider Lasiodora sp. These animals are more long-lived than other arthropods, and may live for approximately twenty years. Such remarkable longevity may result from a highly successful immune system, which in turn is directly correlated with hemocyte function. Since the literature on the genus Lasiodora sp. is limited, the main goal of the present study was to identify the different cell types by optical and transmission microscope. Six hemocyte types were characterized and called prohemocyte, granulocyte type I, granulocyte type II, spherulocyte, oenocytoid and plasmatocyte. Prohemocytes presented a large nucleus, elongated granulocytes type I showed the nucleus with the same cell format, elliptical granulocytes type II showed the central nucleus of identical shape, spherulocytes exhibited the nucleus filling almost the whole cell, oval oenocytoids showed eccentric nucleus and less dense cytoplasm, and irregular plasmatocytes showed a nucleus and no granules in cytoplasm. These polymorphic granulocytes presented a round, elongated, elliptical, oval or irregular profile with large and varied numbers of granules, except for plasmatocytes, that were agranular. Different densities and different concentrations of these granules were found at the periphery of the cell. The possible reasons and implications of differences and similarities between arthropods hemocytes are discussed. It can be concluded that there are six cell types in Lasiodora sp. This study is of the first step in the elucidation of the role these cells play in the circulatory and immune system in spiders.

Morphology of the epidermis of the neotropical catfish Pimelodella lateristriga (Lichtenstein, 1823) with emphasis in club cells.

The epidermis of Ostariophysi fish is composed of 4 main cell types: epidermal cells (or filament containing cells), mucous cells, granular cells and club cells. The morphological analysis of the epidermis of the catfish Pimelodella lateristriga revealed the presence of only two types of cells: epidermal and club cells. The latter were evident in the middle layer of the epidermis, being the largest cells within the epithelium. Few organelles were located in the perinuclear region, while the rest of the cytoplasm was filled with a non-vesicular fibrillar substance. Club cells contained two irregular nuclei with evident nucleoli and high compacted peripheral chromatin. Histochemical analysis detected prevalence of protein within the cytoplasm other than carbohydrates, which were absent. These characteristics are similar to those described to most Ostariophysi studied so far. On the other hand, the epidermal cells differ from what is found in the literature. The present study described three distinct types, as follows: superficial, abundant and dense cells. Differences among them were restricted to their cytoplasm and nucleus morphology. Mucous cells were found in all Ostariophysi studied so far, although they were absent in P. lateristriga, along with granular cells, also typical of other catfish epidermis. The preset study corroborates the observations on club cells' morphology in Siluriformes specimens, and shows important differences in epidermis composition and cell structure of P. lateristriga regarding the literature data.

New insights into sexually dimorphic skin glands of anurans: the structure and ultrastructure of the mental and lateral glands in Hypsiboas punctatus (Amphibia: Anura: Hylidae).

Many anuran species are characterized by sexually dimorphic skin glands. These glands often are concentrated on specific areas, such as the mental region, flanks, or the nuptial pads. We studied the histology and histochemistry of mental and lateral glands in Hypsiboas punctatus, and compared them to skin from other body regions. We describe four types of dermal glands, two types of mucous and two types of serous glands. The mucous glands are formed by a single layered epithelium. The mucocytes surrounding a central lumen are filled with polyhedral granules. Ordinary mucous glands are small sized glands with cubical epithelium, mucoid content, and small granules. Specialized mucous glands are characterized by a larger size, a columnar epithelium, a proteinaceous content and larger granules. Both types of serous glands are syncytial and share some structural features including size, shape, and morphology of secretory granules. However, ordinary and specialized serous glands differ in their histochemical properties, size and appearance of secretory granules, and glandular outlets. The specialized type of mucous glands in H. punctatus resembles most SDSGs described in anurans, whereas the presence of specialized serous glands that are sexually dimorphic is less common. Both specialized glands occur only in mental and lateral regions of males, whereas ordinary mucous and ordinary serous glands occur in males and females.

Analysis of the morphology and distribution of argentaffin, argyrophil and insulin-immunoreactive endocrine cells in the small intestine of the adult opossum Didelphis aurita (Wied-Neuwied, 1826).

The aim of this study was to identify and quantify the argyrophil, argentaffin and insulin-immunoreactive cells (IIC) in the small intestine of the opossum Didelphis aurita. Seven adult male specimens of opossums were investigated. The animals were captured, and their blood insulin levels were determined. After euthanasia, fragments of the small intestine were processed for light microscopy and transmission electron microscopy, and submitted to histochemistry and immunohistochemistry for identification of argyrophil and argentaffin endocrine cells, and IIC. Argyrophil and argentaffin cells were identified in the intestinal villi and Liberkühn crypts, whereas IIC were present exclusively in the crypts. Ultrastructure of the IIC revealed cytoplasmic granules of different sizes and electron densities. The numbers of IIC per mm(2) in the duodenum and jejunum were higher than in the ileum (p<0.05). The animals had low levels of blood insulin (2.8 ± 0.78 µIU/ml). There was no correlation between insulin levels and the number of IIC in the small intestine. The IIC presented secretory granules, elongated and variable morphology. It is believed that insulin secretion by the IIC may influence the proliferation of cells in the Liberkühn crypts, and local glucose homeostasis, primarily in animals with low serum insulin levels, such as the opossum.

Entamoeba histolyticaelectrondense granules secretion in vitro and in vivo: ultrastructural study.

Electron dense granules (EDGs) were identified by transmission electron microscopy in Entamoeba histolytica trophozoites recovered from hamster liver lesions. Abundant granules were present in trophozoites recovered after 15 min of liver inoculation. Variation in the size and morphology of these EDGs was also observed. Numerous granules were present in the plasma membrane when these parasites were incubated for 5 min with MDCK monolayers. Release of these EDGs was suggested by the presence of granules in contact with the surface of the target cell plasma membrane. Parasite phagocytic invaginations were observed after 10 min of parasite-monolayer interaction. In these structures, scarce granules were seen. Granules secretion was corroborated by obtaining of a pellet of these small structures from the incubation of trophozoites with collagen supernatant. Collagenase and gellatinase activity of this pellet was identified in SDS-PAGE gels. EDGs were also present in amebic hamster liver lesions. Our observations corroborate that these granules are secreted and suggest that may participate in the cytopathic effect of E. histolytica both in vitro and in vivo.

Storaged products and presence of acid phosphatase in fat body cells at pre-pupal worker stage of Apis mellifera Linnaeus, 1758 (Hymenoptera, Apidae).

Fat body cells or throphocytes of individuals during beginning of pupation (pre-pupae) of Apis mellifera were collected and studied by routine and cytochemical preparations for transmission electron microscopy (TEM). The results showed that the trophocytes present large reserves of lipids, proteins, and glycogen. Imidazole osmium treatment revealed that lipids are deposited as droplets in the cytoplasm and also within protein granules. Thiery's reaction showed the presence of glycogen inside protein granules. An acid phosphatase reaction was performed to verify the role of this enzyme in the mobilization of stored reserves during metamorphosis. Positive reaction for acid phosphatase was detected at larger protein granules, at the periphery of the large lipid droplets, and free in the cytoplasm. The contents of protein, lipid and glycogen are stored in the trophocytes at larval phase to be used during metamorphosis. The acid phosphatase present in the products stored might be responsible for their metabolization, while acid phosphatase free in cytoplasm might actuates in the trophocytes histolysis that occurs during metamorphosis for energy production.

Production of functional platelet-like particles by the megakaryoblastic DAMI cell line provides a model for platelet biogenesis.

The aim of this study was to evaluate cell maturation and the platelet production capacity of the megakaryoblastic DAMI cell line, to characterize platelet-like particles produced and to investigate the mechanisms involved in their production. DAMI cell maturation was induced by phorbol myristate acetate (PMA) and thrombopoietin (TPO). Expression levels of GATA-1, Fli-1 and NF-E2 were evaluated using real-time PCR and western blot. Platelet-like particles were characterized by the presence of GPIb and GPIIb by flow cytometry, while the soluble fragment of GPIb, glycocalicin, was detected by enzyme immunoassay. Dense and alpha granules were evaluated by mepacrine staining and thrombospondin-1 detection, respectively, and by electron microscopy. Functional capacity of platelet-like particles was studied by measuring P-selectin membrane after thrombin stimulation by flow cytometry and actin polymerization using phalloidin-FITC by immunofluorescence. We found that stimulation of DAMI cells with high concentration of PMA and TPO induced the expression of transcription factors GATA-1 and Fli-1 followed by an increase in the isoform a of NF-E2. Mature DAMI cells give rise to extensions resembling proplatelets and later, produce platelet-like particles expressing GPIIb and GPIb on their surface and containing dense and alpha granules, which were confirmed by electron microscopy. Platelet functionality was demonstrated by the increase in P-selectin membrane expression after thrombin stimulation and by their ability to spread on fibrinogen matrices. DAMI cell line induced to differentiate into mature megakaryocytes is able to produce functional platelets providing a suitable model to study the mechanisms involved in platelet generation.

Adverse effects of 2,4-dichlorophenoxyacetic acid on rat cerebellar granule cell cultures were attenuated by amphetamine.

2,4-Dichlorophenoxyacetic acid (2,4-D), a worldwide-used herbicide, has been shown to produce a wide range of adverse effects in the health--from embryotoxicity and teratogenicity to neurotoxicity--of animals and humans. In this study, neuronal morphology and biochemical events in rat cerebellar granule cell (CGC) cultures have been analyzed to define some of the possible mechanisms involved in 2,4-D-induced cell death. For that purpose, amphetamine (AMPH) that has been shown to accelerate the recovery of several functions in animals with brain injury has been used as a pharmacologycal tool and was also investigated as a possible protecting agent. Addition of 2,4-D to CGC cultures produced a drastic decrease in cell viability, in association with an increased incidence of necrosis and apoptosis, and an increased level of reactive oxygen species, a decrease in glutathione content, and an abnormal activity of some enzymes with respect to the control group. The adverse effects of 2,4-D were partly attenuated in presence of AMPH. Some deleterious effects on several ultrastructural features of the cells, as well as the enhanced incidence of apoptosis, were partially preserved in AMPH-protected cultures as compared with those which were exposed to 2,4-D alone. The collected evidences (1) confirms the previously observed, deleterious effects of 2.4D on the same or a similar model; (2) suggests that the 2,4-D-induced apoptosis could have been mediated by or associated to an oxidative imbalance in the affected cells, and (3) shows some evidence of a protective effect of AMPH on 2,4-D-induced cell death, which could have been exerted through a reduction in the oxidative stress.

Electron microscopic evaluation of the secretory mechanisms of renin from juxtaglomerular cells / Evaluación con microscopía electrónica de los mecanismos secretorios de renina desde las células juxtaglomerulares

Although the structure and the functions of juxtaglomerular cells (JG) have been well defined, there is still a controversy about the secretory mechanisms of renin from these cells. It has been assumed that exocytosis is the main secretory mechanism in these cells in many studies, while others suggest that secretion occurs in a quite different way in these cells. There are several studies suggesting that diacrine secretion, which is very difficult to visualize, might be the other mechanism for secretion of renin. This study is an attempt to find the answers of these questions by identifying the fine structural features of the secretory granules in juxtaglomerular cells. Cyclosporin A (CyA) has been used in the current experimental study since it has already been reported that this drug increases the number of JG cells and stimulates secretion of Renin. Twelve female Sprague-Dawley rats had daily intraperitoneal injections of CyA for ten weeks. Tissue specimens from the kidneys of these animals were examined by electron microscopy. Fine structural characteristics of the secretory granules of juxtaglomerular cells have been examined. Considerable amount of granules, which goes to the exocytotic process, have been observed. Additionally, several cells, which their granules had been secreting their contents in a different way, were found. This was interpreted as the secretion type of diacrine secretion. In conclusion, this in vivo study presents morphologic evidences demonstrating that both exocytosis and diacrine secretion might occur in JG cells. We also had a chance to observe secretory granule probably exhibiting "diacrine secretion", which is very difficult to visualize, at electron microscope level for the first time. This report also provides morphologic proof which shows that these two distinct secretory mechanisms might occur simultaneously in the same juxtaglomerular cell.

Aunque la estructura y las funciones de las células yuxtaglomerulares (JG) han sido bien definidas, todavía existe controversia acerca de los mecanismos de secreción de renina en estas células. Se ha supuesto, en muchos estudios, que la exocitosis es el principal mecanismo de secreción de estas células, mientras que otros autores sugieren que la secreción se produce de una manera muy diferente en estas células. Hay varios estudios que plantean que la secreción diacrina, que es muy difícil de visualizar, podría ser otro mecanismo para la secreción de renina. Este estudio tiene como objetivo encontrar las respuestas a estas interrogantes mediante la identificación de las características estructurales de la secreción de gránulos en las células yuxtaglomerulares. Ciclosporina A (CyA) se ha utilizado en el estudio experimental actual, debido a que se ha informado que este medicamento aumenta el número de células JG y estimula la secreción de renina. Doce ratas hembras Sprague-Dawley fueron diariamente inyectadas por vía intraperitoneal, con CyA durante diez semanas. Las muestras de tejido renal de estos animales fueron examinadas a través de microscopía electrónica. Detalladas características estructurales han sido examinadas en los gránulos secretores de las células yuxtaglomerulares. Se ha observado una cantidad considerable de gránulos, que va con el proceso de exocitosis. Además, se encontaron células que habían secretado el contenido de sus gránulos de manera diferente. Esto fue interpretado como secreción de tipo diacrina. En conclusión, este estudio in vivo presenta evidencias morfológicas que demuestran que tanto la exocitosis y la secreción diacrina podría ocurrir en células JG. También tuvimos la oportunidad de observar probables gránulos secretores, que mostrarían "la secreción diacrina", que es muy difícil de visualizar, a nivel de microscopía electrónica. Este informe también proporciona la prueba morfológica que demuestra que estos dos mecanismos...

Ultrastructural megakaryocyte modifications after vanadium inhalation in spleen and bone marrow.

Previous reports from our laboratory informed in mice an increase in platelets in blood, and megakaryocytes in spleen and bone marrow after vanadium inhalation. This element has become important in recent years because of its increased presence as an air pollutant. With this precedent, we evaluate the ultrastructural modifications in MKs from the spleen and bone marrow in our mouse experimental model. Mice inhaled 0.02 M V(2)O(5) 1 h twice a week for 12 weeks. Tissues were processed for transmission electron microscopy. Results indicate an increase in the size and cytoplasmic granular content, as well as nuclear changes in MKs of exposed mice, changes which correlate with the time of exposure. Modifications in MKs described here suggest that inhaled vanadium induce megakaryocytic maturation, a raise in its granules content and demarcation membrane systems, which may lead to a rise in circulating platelet production and an increased risk for thromboembolic events.

Mammalian Staufen 1 is recruited to stress granules and impairs their assembly.

Stress granules are cytoplasmic mRNA-silencing foci that form transiently during the stress response. Stress granules harbor abortive translation initiation complexes and are in dynamic equilibrium with translating polysomes. Mammalian Staufen 1 (Stau1) is a ubiquitous double-stranded RNA-binding protein associated with polysomes. Here, we show that Stau1 is recruited to stress granules upon induction of endoplasmic reticulum or oxidative stress as well in stress granules induced by translation initiation blockers. We found that stress granules lacking Stau1 formed in cells depleted of this molecule, indicating that Stau1 is not an essential component of stress granules. Moreover, Stau1 knockdown facilitated stress granule formation upon stress induction. Conversely, transient transfection of Stau1 impaired stress granule formation upon stress or pharmacological initiation arrest. The inhibitory capacity of Stau1 mapped to the amino-terminal half of the molecule, a region known to bind to polysomes. We found that the fraction of polysomes remaining upon stress induction was enriched in Stau1, and that Stau1 overexpression stabilized polysomes against stress. We propose that Stau1 is involved in recovery from stress by stabilizing polysomes, thus helping stress granule dissolution.

Effects of H+ concentration on amorphous mineral granules: structural stability and elemental mobilization.

Phosphate-rich amorphous mineral granules (AMG) have been studied in a number of organisms, and show different physical and chemical properties according to their organic and mineral composition. We studied AMG isolated from the hepatopancreas of the land crab Ucides cordatus, which were subjected to different pHs in order to mimic the possible effects of H(+) on these structures. We used scanning and transmission electron microscopy (SEM, TEM), energy-filtering transmission electron microscopy (EFTEM), energy-dispersive X-ray analysis (EDXA) and nuclear magnetic resonance (NMR). TEM showed that granules were structurally disrupted when subjected to pH 5. The granules contain a soluble fraction that is rich in orthophosphate, which was the most abundant form of phosphate, although pyrophosphate and glucose-6-phosphate were also detected by (31)P NMR analysis. The redistribution of elements in the structure and pH conditions is discussed, focusing on their possible implications for AMG structure, function and dynamics.

Relationship between the physicochemical properties of starches and the glycemic indices of some Jamaican yams (Dioscorea spp.).

Starch granules from round leaf yellow yam (RY), Lucea yam (LY), white yam (WY), and Chinese yam (CY) grown in Jamaica were isolated and the relationship between starch amylose content, crystallinity, microscopic properties, in vitro digestibility, and the glycemic index (GI) of the tubers was investigated. The results indicate that RY had the highest amylose content (265.30 +/- 0.09 g/kg starch) while CY the lowest (111.44 +/- 0.03 g/kg starch). A corresponding variation in starch digestibility and GI was also observed, as CY which had the highest in vitro digestibility had the highest GI (21.27 +/- 0.01 and 97.42 +/- 0.62%, respectively), while RY, LY, and WY starches with low digestibility had lowest GI. Differences in the crystalline pattern of the different starches were observed, where RY, LY, and WY displayed the type B crystalline pattern while CY had the intermediate crystallite (type C).