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M I Berría

Publications and source records attributed to M I Berría.

At least 19 recordsLinked to original sources
PubMed2003

Long-lasting astrocyte reaction to persistent Junin virus infection of rat cortical neurons.

Immunoperoxidase labeling was performed in histological sections from rat brain harvested during acute (10-30 days), clinically inapparent (90-270 days) and late (450-540 days) stages of Junin virus-induced neurological disease. In frontoparietal cortex, count of viral antigen (+) neurons peaked during the acute period (27.7+/-6.8), dropped within the intermediate (4.8+/-4.0 to 1.4+/-1.1) and increased (7.6+/-4.3) at the onset of the late neurological syndrome. In infected vs. control rats, the number of GFAP (+) astrocytes maximized during the acute stage (19+/-4 vs. 11+/-5), and from the end of the intermediate (27+/-5 vs. 21+/-5) up to the late (37+/-7 vs. 26+/-6) periods. In turn, surface density of GFAP (+) material in infected samples peaked at 0.196+/-0.066, while it failed to exceed 0.090+/-0.043 in controls. Both astrocyte hypertrophy relapsing into chronicity, as depicted by surface density, and astrocyte hyperplasia preceding the onset of the late neurological syndrome, support their pathogenic contribution to disease expression.

Animals↗
PubMed2001

Host selenium status selectively influences susceptibility to experimental viral myocarditis.

The purpose of the present work was to determine whether dietary selenium (Se) deficiency could influence the injurious effect of human viruses other than Coxsackie virus B3 (CVB3) on mouse heart. Weanling C3H/HeN mice were fed a Se-deficient or Se-adequate diet for 4 wk and then were inoculated intraperitoneally with one of the following viruses: Coxsackie virus B1 (CVB1), echovirus 9 (EV9), Coxsackie virus A9 (CVA9), or herpes simplex 1 (HSV1). Polio virus 1 (PV1) was employed as a negative control. Prior to inoculation, mean serum Se levels were 430 versus 61 ng/mL in adequate versus deficient mice, respectively. Ten days later, hearts were removed and processed by routine histological procedures. Cardiac lesions were scored according to the number and size of myocarditic foci. Significantly greater heart damage resulting from CVB1 and EV9 was observed in Se-deficient than in Se-adequate mice, and the Se status had no influence on CVA9-induced myocarditis. In contrast, heart damage caused by HSV1 was significantly milder in Se-deficient than in Se-adequate mice. Therefore, it may be concluded that the Se status of the murine host selectively influences the degree of viral-induced myocarditic lesions.

Animals↗
PubMed2000

A quantitative approach to correlate astrocyte differentiation and phagocytic activity.

A triple staining procedure (PAP labeling for GFAP, PAS reaction for added yeast cells and hematoxylin for nuclear staining of the whole cell monolayer) had disclosed that Junin virus infection enhanced phagocytic activity by inducing greater astrocyte differentiation. Here, we resorted to a mathematical approach for simultaneous evaluation of astrocyte differentiation and potential phagocytosis. At light microscopy level, the total number of: a) PAS-stained yeast cells, b) PAS-stained yeast cells associated to GFAP-positive astrocytes, c) GFAP-positive astrocytes, and d) total number of GFAP-labeled and non-labeled astrocytes, were counted within the monolayer area delimited by a grid with a total area of 0.01 mm2. As the percentage of PAS-stained yeast cells associated to GFAP-positive astrocytes correlated significantly with the percentage of GFAP-positive astrocytes for the three yeast cell incubation times (24, 48 and 72 h), a mathematical approach involving a so-called beta parameter representing the percentage of differentiated astrocytes capable of taking up 50% of added yeast cells, was developed. Since beta value dropped along yeast cell incubation time, and more markedly in Junin-virus infected samples, a numerical value was thus available to assess enhanced phagocytic activity in astrocytes undergoing differentiation. Therefore, the application of a mathematical approach to cell monolayers subjected to current staining techniques, allows more objective analysis of data provided by cursory visualization at light microscopy level.

Animals↗
PubMed1999

Cell differentiation increases astrocyte phagocytic activity. A quantitative analysis of both GFAP labeling and PAS-stained yeast cells.

Since efficiency of phagocytic potential in activated astrocytes is still a subject of controversy, an attempt was made to quantify simultaneously phagocytic activity and astrocyte differentiation. Resorting to Junin virus, known to induce astrocyte activation, infected vs control samples of cultured rat astroglial cells were serially harvested up to day 12 post-inoculation (pi), and subjected to a triple staining procedure consisting in immunoperoxidase labeling of GFAP, periodic acid-Schiff (PAS) reaction in added baker's yeast cells and hematoxylin for nuclear staining of the whole cell monolayer. Adopting GFAP labeling as a specific marker of astrocyte differentiation, the immunoprecipitate development over time was measured. Direct calculation of the initial reaction rate was feasible given its linear behavior during the first 10 min, so that GFAP amount was regarded proportional to peroxidase activity. As determined by digital image analysis, mean optical density (MOD) values of GFAP in infected samples increased from 0.618 +/- 0.082 at day 1 pi to 0.825 +/- 0.125 at day 3, leveling off at 1.010 +/- 0.101 as from day 9, while control uninfected samples remained unchanged at roughly 0.6 during the entire observation period. In turn, phagocytosis was quantified by PAS staining densitometry, whose intensity varied according to wall degradation of yeast cells. MOD levels of PAS-stained phagocytized yeast cells were significantly lower (p < 0.05) in infected vs control cultures at 48 and 72 h following their addition to the astroglial monolayer. According to simultaneous quantification of two components of astrocyte response to viral infection, it is concluded that phagocytic activity increases with astrocyte differentiation.

Animals↗
PubMed1996

Age-dependent morphological changes in dBcAMP-treated astrocytes.

Since changes in cell morphology are conspicuous features of astrocyte reaction, we resorted to an histometric approach to evaluate age influence on such morphological response to activating stimuli. To this end, first subculture of rat brain astrocytes at 1, 9 or 21 days in vitro (DIV) were treated during 2 hs with 1 mM of dBcAMP, a chemical compound known to induce cell differentiation. Following treatment, immunoperoxidase labeling of GFAP, specific marker of astrocyte activation, was carried out. Although total count of GFAP-positive cell foci was greater in treated samples in all times tested, when such cell foci were evaluated by image analysis, differences between perimeter/area ratios of such foci were only statistically significant at 1 DIV. It may be concluded that while dBcAMP effect is maintained despite astrocyte aging, the morphological pattern of response varies markedly along the observation period.

Animals↗
PubMed1995

Glial fibrillary acidic protein (GFAP) immunochemical profile after junin virus infection of rat cultured astrocytes.

Cultured astrocytes derived from newborn rat brain were inoculated with Junin virus (JV) to characterize their response to infection by means of their glial fibrillary acidic protein (GFAP) immunochemical profile. Samples from 1 to 11 days post-inoculation (pi), as well as matched controls, were serially harvested for GFAP labeling by peroxidase-antiperoxidase (PAP) method. It was only at day 3 that significantly greater values of GFAP staining (P < 0.05) were disclosed by three complementary approaches: image analysis, ELISA and immunoblot densitometry. Since such increase was abolished by Triton X-100 treatment, soluble GFAP fraction appeared responsible for the early though transient enhancement of GFAP immunoreactivity that followed viral inoculation.

Animals↗
PubMed1995

Growth inhibition of herpes simplex virus-type 1 in calphostin C-treated astrocytes.

The aim was to evaluate the effects of calphostin C (CC), a protein kinase C inhibitor, on lytic herpes simplex virus-type 1 infection of cultured rat astrocytes. At 24 h postinjection, the cell culture receiving CC treatment at 50 nM concentration showed decreased cell detachment and retraction versus untreated infected controls; likewise, the infective virus yield was significantly lower in a dose-dependent manner. In contrast, image analysis failed to disclose differences in viral antigen immunolabeling at low drug concentrations thus suggesting that CC-induced inhibition of cytopathic effects and infectivity taken place through mechanisms not involving viral protein synthesis. Given the low dose required and the apparent lack of cytotoxic effects, present findings encourage additional studies on CC antiviral potential in the whole organism.

Animals↗
PubMed1994

Neural spread of Junin virus in intraperitoneally inoculated rats.

On the basis of an already demonstrated Junín virus (JV) neural route after peripheral footpad infection of newborn rats, here we attempted to determine the viral pathway following intraperitoneal inoculation. As from the 2nd week post-infection, neurological disease developed reaching 84% mortality at 30 days. Immunoperoxidase labeling of viral antigen, concomitantly with infectivity assays and histological examination, was carried out in serially harvested samples. Whenever infectivity was detected, whether by viral rescue from coculture or by conventional isolation, viral antigen staining was achieved. Infective JV was present at threshold levels in spleen and liver from days 2 to 10, and in blood from days 5 to 15. In neural tissues, viral antigen was initially disclosed at day 5 in thoracic rachideal ganglia and related spinal cord segments. From day 7 thereafter, the entire spinal cord was involved; at this stage, first evidence of viral infection was found in brain stem, with subsequent spread to other encephalon structures at day 10. According to harvested samples, no significant differences were found in labeled cell percentages at thoracic vs cervical or lumbar levels of spinal cord. In contrasts, greater involvement of cerebral cortex versus brain stem, hippocampus or cerebellum was demonstrated shortly before death. Although JV antigen was overwhelmingly predominant in neurons, no morphological changes were apparent in such cells. Since rachideal spinal ganglia and spinal cord infection invariably preceded viral spread to encephalon, concomitantly with viral clearance from lymphoreticular organs and blood, a neural pathway seems warranted.

Animals↗
PubMed1993

Differential behaviour in pancreas and heart of two coxsackievirus B3 variants.

In order to characterize viral kinetics and pathogenic properties of two intratypic variants of coxsackievirus B type 3, Balb/c mice were intraperitoneally inoculated and serial samples harvested from days 2 to 28. Although both CB3o (amyocarditic) and CB3m (myocarditic) variants induced similar early infectivity titres in pancreas, only the latter led to severe acinar necrosis, followed in turn by patent viraemia and subsequent focal myocarditis. Nevertheless, when both variants were inoculated in cultured cardiac cells, neither infectivity nor cell death rate differed noticeable. Therefore, our findings indicate that overt myocarditis is not attributable to contrasting cardiomyocyte susceptibility to the tested variants but rather to prior viral events in pancreatic tissues.

Animals↗
PubMed1992

Immunoperoxidase tracing of Junin virus neural route after footpad inoculation.

To determine the pathway adopted by peripherally inoculated Junin virus (JV) to reach the CNS, rat tissues were serially harvested to trace the sequence of viral progression from right hind footpad to brain. Immunoperoxidase (PAP) labeling of viral antigen, concomitantly with infectivity assays and histological examination of each selected sample, were carried out. As from the 2nd week post-infection (pi), neurological disease inducing 100% mortality at 1 month was evident. At day 5 pi, viral antigen was first detected at footpad level in epidermic and dermic cells, as well as in neighbouring myocytes; labeled macrophages infiltrating small nerve branches were also disclosed. As from 10-15 days pi, viral antigen became apparent along ipsilateral sciatic nerve structures and within lumbar spinal ganglion neurons, followed by a fast viral spread throughout CNS neurons that involved spinal cord and brain. Concurrent histopathology featured minimal inflammatory reaction together with generalized astrocytic activation. Hematogenous viral transport was negligible, since JV was isolated much earlier and in higher infectivity titers in neural tissues than in blood. It may be concluded that after viral replication in footpad, JV neural route was demonstrated by its PAP labeling from peripheral nerves to cerebral cortex.

Animals↗
PubMed1992

Extracellular matrix remodelling after coxsackievirus B3-induced murine myocarditis.

Weanling inbred Balb/c mice were intraperitoneally inoculated with a myocarditic variant of coxsackievirus B3. At days 1, 2, 4, 6, 8, 10, 14, 24 and 30 post-infection (p.i.), myocardial tissue was harvested for viral infectivity titrations and histological studies, including routine techniques (haematoxylin-eosin, Masson trichrome and von Kossa) and specialized procedures (silver impregnation for reticulin, picrosirius red stain for collagen and immunoperoxidase labelling for laminin). Virus was isolated as from day 2, reached maximal infectivity at days 6-8 and decreased gradually to become undetectable by day 14. Early histological findings during the 1st week consisted mainly of scattered foci of necrotic myocytes showing calcium deposits; slight mononuclear cell infiltration and fragmentation of both reticulin fibres and pericellular laminin were also present. From the 2nd up to 4th week p.i., inflammatory reaction abated concomitantly with the gradual development of fibrosis, as evidenced by reticulin fibre thickening, irregular laminin distribution and collagen fibre increase. Our results suggest that viral-induced necrosis is able to trigger marked extracellular matrix remodelling even in the case of minimal inflammation.

Animals↗
PubMed1991

Murine acinar pancreatitis preceding necrotizing myocarditis after Coxsackievirus B3 inoculation.

Balb/C weanling mice were inoculated intraperitoneally with a myocarditic variant of coxsackie-virus B3, with the aim of characterizing more fully the cell damage induced in the heart as well as in other organs. During the first week postinfection (pi), all animals developed acinar pancreatitis, followed by focal myocarditis. In accordance with the increasing infectivity titers, such progressive histopathological changes correlated with local viral replication. From day 4 pi, acinar degeneration accompanied by diffuse inflammatory exudate was observed in the pancreas, followed by fatty tissue replacement by day 8. In the heart, focal necrosis rather than inflammatory reaction first appeared at 4 days pi and became widespread by 6-8 days pi. Necrotic foci usually presented calcium deposits, with absence of myofibrils in the affected fibers. The fact that both periodic acid Schiff (PAS) and Best carmine staining remained positive even after diastase treatment ruled out basophilic necrosis. In summary, the pancreas appeared to be the site of primary viral replication leading to viremia.

Animals↗
PubMed1991

A triple staining procedure to evaluate phagocytic role of differentiated astrocytes.

To determine whether phagocytic activity is affected by a viral infection known to induce astrocyte differentiation, a triple procedure (PAP labeling for GFAP, PAS reaction for added baker's yeast cells and hematoxylin for nuclear staining of the whole monolayer) was applied to Junin virus-inoculated cultures, as well as matched controls. The three-step staining simplified yeast cell count for subsequent statistical analysis, which discerned preferential uptake by differentiated rather than immature astrocytes. Accordingly, greater cell maturation induced by Junin virus was concomitant with early enhancement of phagocytic activity.

Acid Phosphatase↗
PubMed1990

Fibronectin involvement following herpes simplex infection of cultured rat astrocytes.

To evaluate the potential impact of a strongly neurotropic virus on the matricial fibronectin (FN) of a given neural cell type, first subculture of rat astrocytes were inoculated with either a low (0.1-0.5) or a high MOI (10-100) of Herpes simplex virus-type 1 (HSV-1). Infected samples, as well as matched controls, were harvested from 12 to 72 h post-inoculation and processed for extracellular FN labeling by the peroxidase-antiperoxidase (PAP) method. Following low MOI, multinucleated cell formation and syncytial development drastically modified peripheral FN, since the typical loose network was largely replaced by a patch-like appearance. At high MOI, when viral action caused further cytoplasmic retraction leading to rounded or stellate cells, the FN pattern was remarkably altered, even with total FN loss around highly retracted cells. It may be concluded that a virus such as HSV-1, capable of modifying astrocyte morphology, induces a redistribution or loss of pericellular FN.

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