Lysosomal Membrane Stability in Hemocytes and Micronuclei in Gills of Perumytilus purpuratus Lamarck 1819 (Bivalvia: Mytilidae) Exposed to Copper.

The aim of this study was to determine the cytotoxic and genotoxic effects of copper on the bivalve Perumytilus purpuratus. The individuals were exposed to three copper concentrations: 1, 30 and 45 µg L-1 for 24, 48 and 96 h. Lysosomal membrane stability in hemocytes was determined through the neutral red retention time (NRRT) and micronucleus (MN) frequency tests in hemocytes and gills. The results show that the NRRT decreased significantly at 30 µg L-1 after 48 h of exposure. The frequency of MN was significantly greater in gills after 24 h in all concentrations tested. Copper is cytotoxic from 30 µg L-1 and genotoxic from 1 µg L-1. The use of these biomarkers of effects in P. purpuratus is proposed as an early warning tool for monitoring in environmental assessment of coastal ecosystems impacted by mining activities.

Mitochondrial swelling and incipient outer membrane rupture in preapoptotic and apoptotic cells.

Outer mitochondrial membrane (OMM) rupture was first noted in isolated mitochondria in which the inner mitochondrial membrane (IMM) had lost its selective permeability. This phenomenon referred to as mitochondrial permeability transition (MPT) refers to a permeabilized inner membrane that originates a large swelling in the mitochondrial matrix, which distends the outer membrane until it ruptures. Here, we have expanded previous electron microscopic observations that in apoptotic cells, OMM rupture is not caused by a membrane stretching promoted by a markedly swollen matrix. It is shown that the widths of the ruptured regions of the OMM vary from 6 to 250 nm. Independent of the perforation size, herniation of the mitochondrial matrix appeared to have resulted in pushing the IMM through the perforation. A large, long focal herniation of the mitochondrial matrix, covered with the IMM, was associated with a rupture of the OMM that was as small as 6 nm. Contextually, the collapse of the selective permeability of the IMM may precede or follow the release of the mitochondrial proteins of the intermembrane space into the cytoplasm. When the MPT is a late event, exit of the intermembrane space proteins to the cytoplasm is unimpeded and occurs through channels that transverse the outer membrane, because so far, the inner membrane is impermeable. No channel within the outer membrane can expose to the cytoplasm a permeable inner membrane, because it would serve as a conduit for local herniation of the mitochondrial matrix.

Effects of the extract of Anemopaegma mirandum (Catuaba) on Rotenone-induced apoptosis in human neuroblastomas SH-SY5Y cells.

Parkinson's disease (PD) is one of the most important neurodegenerative worldwide disorders. It is characterized by a selective and progressive degeneration of dopaminergic neurons, causing a series of symptoms which might ultimately induce programmed cell death. The potential cytoprotective effects of one of the commercial extracts of Anemopaegma mirandum (Catuaba), a Brazilian tree, on Rotenone-induced apoptosis in human neuroblastomas SH-SY5Y cells was demonstrated. The cell viability, analysis of cellular morphology, nuclei morphology and ultra structural research were done by MTT-tetrazole (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, phase contrast microscopy, stained with Hoechst 33258 and electron microscopy transmission, respectively. Three different concentrations of Catuaba extract were used (0.312, 0.625 and 1.250 mg/mL). These extracts promoted an increase of 22.3+/-3.6%, 22.0+/-2.1% and 15.8+/-0.7% on the cell viability. Notable changes in the cellular morphology, condensation of the cell body, nuclear fragmentation and condensation into discrete dense chromatin clumps were observed when the cells were treated with 300 nM Rotenone for 48 h. These effects were partially altered when the extract of A. mirandum was added to the Rotenone treatment. Ultra structural analysis by electron microscopy demonstrated that citoplasmatic membranes and mitochondria membrane were also clearly preserved in the group treated with the extract. Therefore, in this study, our findings indicated that extracts of A. mirandum have cytoprotective effects on Rotenone-induced apoptosis in human neuroblastomas SH-SY5Y cells.

Absence of vacuolar membrane involving Toxoplasma gondii during its intranuclear localization.

Tachyzoites of Toxoplasma gondii were located inside the nucleus of both skeletal muscle cells infected in vitro and peritoneal exudate cells collected from infected mouse in vivo. Ultrastructural analysis demonstrated that T. gondii invades the nucleus of host cells by the parasite apical region and with constriction of its body. We noted that the rhoptry, a secretory organelle of the parasite that is involved in the host cell invasion mechanism, was empty in the intranuclear T. gondii. The parasites were found in the nuclear matrix without evidence of the vacuolar membrane. Frequently, new parasites invaded host cell nucleus, which was already infected. The significance of this nuclear invasion could reflect an alternative route of T. gondii for its transitory survival or an escape mechanism from the host immune response during the in vivo infection (or both).

Apoptogenic effect of the lipophilic o-naphthoquinone CG 10-248 on rat hepatocytes: light and electron microscopy studies.

CG 10-248 (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione; CG-NQ), a beta-lapachone analogue, modified the ultrastructure of rat hepatocytes, as demonstrated by light and electron microscopy. After 4 h incubation with 100 microM CG-NQ, the following effects were observed: (a) nuclear chromatin condensation; (b) chromatin fragmentation; (c) displacement of mitochondria, concentrated around the nucleus; (d) disruption or expansion of mitochondrial outer or inner membranes, respectively; (e) displacement and alteration of endoplasmic reticulum (rough and smooth); (f) decrease of microvilli; (g) blebbing of plasma membrane and production of apoptotic bodies formed by folding of plasma membrane fragments around mitochondria or peroxysomes; and (h) production of hydrogen peroxide. Expression of such effects varied according to hepatocyte samples and taken together strongly support an apoptotic action of CG-NQ dependent on "reactive oxygen species".

Apoptogenic effect of the lipophilic o-naphthoquinone CG 10-248 on rat hepatocytes: light and electron microscopy studies

CG 10-248 (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione; CG-NQ), a beta-lapachone analogue, modified the ultrastructure of rat hepatocytes, as demonstrated by light and electron microscopy. After 4 h incubation with 100 microM CG-NQ, the following effects were observed: (a) nuclear chromatin condensation; (b) chromatin fragmentation; (c) displacement of mitochondria, concentrated around the nucleus; (d) disruption or expansion of mitochondrial outer or inner membranes, respectively; (e) displacement and alteration of endoplasmic reticulum (rough and smooth); (f) decrease of microvilli; (g) blebbing of plasma membrane and production of apoptotic bodies formed by folding of plasma membrane fragments around mitochondria or peroxysomes; and (h) production of hydrogen peroxide. Expression of such effects varied according to hepatocyte samples and taken together strongly support an apoptotic action of CG-NQ dependent on reactive oxygen species.

Apoptogenic effect of the lipophilic o-naphthoquinone CG 10-248 on rat hepatocytes: light and electron microscopy studies

CG 10-248 (3,4-dihydro-2,2-dimethyl-9-chloro-2H-naphtho[1,2b]pyran-5,6-dione; CG-NQ), a beta-lapachone analogue, modified the ultrastructure of rat hepatocytes, as demonstrated by light and electron microscopy. After 4 h incubation with 100 microM CG-NQ, the following effects were observed: (a) nuclear chromatin condensation; (b) chromatin fragmentation; (c) displacement of mitochondria, concentrated around the nucleus; (d) disruption or expansion of mitochondrial outer or inner membranes, respectively; (e) displacement and alteration of endoplasmic reticulum (rough and smooth); (f) decrease of microvilli; (g) blebbing of plasma membrane and production of apoptotic bodies formed by folding of plasma membrane fragments around mitochondria or peroxysomes; and (h) production of hydrogen peroxide. Expression of such effects varied according to hepatocyte samples and taken together strongly support an apoptotic action of CG-NQ dependent on reactive oxygen species. (AU)

[Idiopathic membranous glomerulonephritis]. / Glomerulonefritis membranosa idiopática.

The only case of idiopathic membranous glomerulonephritis seen out of 106 nephropathic patients biopsied in the two last years at the C. H. 20 de Noviembre, I.S.S.S.T.E., is reported. Twenty-six showed nephrotic syndrome not associated to systemic disease, including the present case, which gave us an incidence of 3.8% of this entity. We were impressed by the low frequency of this disease, so we made a statistical epidemiological analysis localizing it geographically based on the available medical literature. On comparing the results of these studies we confirmed that this disease is significantly low in our environment.