PubMed Health⌕ Search

Biomedical subjects

E Rocha

Publications and source records attributed to E Rocha.

At least 19 recordsLinked to original sources
PubMed2003

Effect of chronic stress on spatial memory in rats is attenuated by lithium treatment.

Stress is known to alter cognitive functions, such as memory, and it has been linked to the pathophysiology of mood and anxiety disorders. Chronic lithium treatment is used in some psychiatric disorders and has been suggested to act upon mechanisms which can enhance neuronal viability. The purpose of this work is to investigate a possible effect of lithium treatment in a chronic stress model. Adult male Wistar rats were divided in two groups, control and chronically stressed, treated either with normal chow or with chow containing LiCl for 40 days. Stress treatment was a chronic variable stress model, consisting of different stressors which were applied in a random fashion, once a day, every day. Memory was assessed by using the water maze task. The results demonstrated a marked decrease in reference memory in the water maze task in chronically stressed rats. This effect was attenuated by lithium treatment in all the parameters considered. No effect was observed in the working memory. These results indicate that lithium treatment may counteract some effects of chronic stress situations, particularly concerning spatial memory.

Animals↗
PubMed2003

Stereological characterization of bovine (Bos taurus) cumulus-oocyte complexes aspirated from small antral follicles during the metestrous and proestrous phases.

Bovine cumulus-oocyte complexes (COCs) aspirated from slaughterhouse ovaries are used for in vitro maturation and fertilization after selection on the basis of morphological appearance of the cumulus and ooplasm. In this context, a quantitative characterization of COCs could provide additional criteria for selecting the most competent complexes. Bovine COCs from small (1-4mm) antral follicles were aspirated from metestrous and proestrous stage ovaries of Holstein-Friesian cows, fixed in glutaraldehyde, randomly embedded in glycol-methacrylate, and sectioned at 20 microm. The unbiased nucleator principle of stereology was used for estimating the mean volumes of complexes, oocytes, cumulus cells, and nuclei of oocytes and cumulus cells. The thickness of the zona pellucida and the relative numerical percentages of the several morphological types (C1, C2 and C3) of cumulus cells were also evaluated. The optical dissector procedure was used for cumulus cell sampling. Quantitative data show that the variability among complexes is generally high, especially for the volume of COCs. There were no linear correlations between the studied parameters, except between the volume of the oocyte and nucleus at metestrus. At proestrus, the volumes of COCs, oocytes and nuclei of oocytes, the volume of follicular cells and the thickness of the inner zona pellucida, were significantly higher than at metestrus. The relative numerical frequency of follicular type C1 cells was lower whereas that of type C3 cells was higher at proestrus than at metestrus. In conclusion, small antral follicles had larger COCs and oocytes at proestrus compared to metestrus and the COCs also had a higher percentage of follicular type C3 cells. Results suggest that for the same type of follicle size there may exist different functional populations of COCs at distinct stages of the bovine ovarian cycle.

Animals↗
PubMed2003

Efficacy and safety of bemiparin compared with enoxaparin in the prevention of venous thromboembolism after total knee arthroplasty: a randomized, double-blind clinical trial.

In this randomized, multicenter, controlled, double-blind, sequential trial, 381 patients undergoing primary total knee replacement were randomly assigned to receive subcutaneous injections of either 3500 IU anti-factor Xa of bemiparin sodium, first dose 6 h after surgery, or 40 mg of enoxaparin, first dose 12 h before surgery, followed by daily doses for 10 +/- 2 days, for the prophylaxis of venous thromboembolism. The primary efficacy endpoint was venous thromboembolism up to postoperative day 10 +/- 2, defined as deep vein thrombosis detected by mandatory bilateral venography, documented symptomatic deep vein thrombosis and/or documented symptomatic pulmonary embolism. The primary safety endpoint was major bleeding. Eighty-seven percent of all randomized patients (333 of 381 patients) were evaluable for efficacy. The incidence of venous thromboembolism was 32.1% (53 of 165 patients) in the bemiparin group and 36.9% (62 of 168 patients) in the enoxaparin group. The absolute risk difference was 4.8% in favor of bemiparin [95% confidence interval (CI), -15.1% to 5.6%; non-inferiority P-value: 0.02; superiority P-value: 0.36]. The incidence of proximal deep vein thrombosis was 1.8% (three of 165 patients) in the bemiparin group and 4.2% (seven of 168 patients) in the enoxaparin group. Major bleeding occurred in six patients (three in each group). There were no deaths during the study. This trial shows that bemiparin started postoperatively is as effective and safe as enoxaparin started preoperatively in the prevention of venous thromboembolism in patients undergoing total knee replacement.

Aged↗
PubMed2002

ATP stimulates human placental 11beta-hydroxysteroid dehydrogenase type 2 activity by a novel mechanism independent of phosphorylation.

The human placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) is believed to play a key role in fetal development since this enzyme protects the fetus from exposure to high levels of maternal cortisol by virtue of converting maternal cortisol to its inert metabolite cortisone. The present study was undertaken to examine the effect of ATP on 11beta-HSD2 activity in human placental microsomes. Enzyme activity, reflected by the rate of conversion of cortisol to cortisone, was stimulated more than six-fold by 0.5 mM ATP (EC(50) = 0.2 mM). Such stimulation appears to be mediated through a novel mechanism independent of ATP-induced phosphorylation of the reaction components since AMP-PNP, a non-hydrolyzable analogue of ATP, was equally effective. The ATP-induced stimulation of 11beta-HSD2 activity is adenine nucleotide specific in that a similar stimulation was observed with ADP and AMP but not with CTP, GTP, or UTP. Furthermore, ATP increased the maximal velocity (V(max)) of the 11beta-HSD2 catalyzed conversion of cortisol to cortisone without altering the apparent K(m) of 11beta-HSD2 for cortisol, suggesting that ATP may stimulate enzyme activity by interacting with the enzyme at a site other than that involved in substrate binding. In conclusion, the present study has identified ATP as a novel regulator of human placental 11beta-HSD2 in vitro. It is conceivable that intracellular ATP may have a profound effect on 11beta-HSD2 function in vivo.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2001

An investigation of the neuroprotective effect of lithium in organotypic slice cultures of rat hippocampus exposed to oxygen and glucose deprivation.

Brain ischemia results in cellular degeneration and loss of function. Here we investigated the neuroprotective effect of lithium in an in vitro model of ischemia. Organotypic hippocampal slice cultures were exposed to oxygen and glucose deprivation. Cellular death was quantified by measuring uptake of propidium iodide (PI). Lithium chloride (0.2-1.2 mM) was added to the medium before, during and after lesion induction. A decrease in incorporation of PI was observed, indicating a neuroprotective effect in all doses tested. We also studied the effect of lithium on the phosphorylation of HSP27, a heat shock protein involved in cellular protection in its dephosphorylated state. In the lesioned hippocampus, 0.4 mM lithium chloride decreased the proportion of phosphorylated HSP27 to total HSP27. These results suggest that lithium may be useful in the treatment of brain ischemia.

Animals↗
PubMed2001

Thrombopenic purpura induced by a monoclonal antibody directed to a 35-kilodalton surface protein (p35) expressed on murine platelets and endothelial cells.

OBJECTIVE: With the aim of obtaining monoclonal antibodies (mAbs) against mouse endothelial surface antigens, immunization of rats with a mouse-derived endothelial cell line (PY4.1) and subsequent hybridoma production were performed. MATERIALS AND METHODS: One of the mAbs produced by hybridoma EOL5F5 was selected for its surface binding to endothelial cell lines, and identification of the mAb-recognized antigen was performed by immunoprecipitation. Experiments were performed to analyze the effects of EOL5F5 on systemic administration to mice. RESULTS: EOL5F5-recognized antigen was a single band of 35 kDa under reducing and nonreducing conditions, features that do not match other known differentiation antigens with comparable tissue distribution. In vivo administration of purified EOL5F5 mAb to mice (n = 20) induced intense cutaneous purpura as well as severe but transient thrombocytopenia. Expression of EOL5F5-recognized antigen was detected on platelets from which it immunoprecipitated a moiety of identical electrophoretic pattern in SDS-PAGE, as the one recognized on endothelial cells. Immunohistochemically, EOL5F5-recognized antigen (p35) also was expressed on dermal capillaries, suggesting that, in addition to thrombocytopenia, damaging effects of the antibody on endothelial cells also might cause the observed purpura. CONCLUSIONS: Our results show induction of thrombocytopenic purpura in mice with an mAb against a single antigenic determinant expressed on both platelets and endothelium. EOL5F5 mAb injection sets the stage for useful experimental models that resemble immune thrombocytopenic purpura.

Animals↗
PubMed2001

Age-related changes in rat cerebellar basket cells: a quantitative study using unbiased stereological methods.

Cortical cerebellar basket cells are stable postmitotic cells; hence, they are liable to endure age-related changes. Since the cerebellum is a vital organ for the postural control, equilibrium and motor coordination, we aimed to determine the quantitative morphological changes in those interneurons with the ageing process, using unbiased techniques. Material from the cerebellar cortex (Crus I and Crus II) was collected from female rats aged 2, 6, 9, 12, 15, 18, 21 and 24 mo (5 animals per each age group), fixed by intracardiac perfusion, and processed for transmission electron microscopy, using conventional techniques. Serial semithin sections were obtained (5 blocks from each rat), enabling the determination of the number-weighted mean nuclear volume (by the nucleator method). On ultrathin sections, 25 cell profiles from each animal were photographed. The volume density of the nucleus, ground substance, mitochondria, Golgi apparatus (Golgi) and dense bodies (DB), and the mean surface density of the rough endoplasmic reticulum (RER) were determined, by point counting, using a morphometric grid. The mean total volumes of the soma and organelles and the mean total surface area of the RER [SN (RER)] were then calculated. The results were analysed with 1-way ANOVA; posthoc pairwise comparisons of group means were performed using the Newman-Keuls test. The relation between age and each of the parameters was studied by regression analysis. Significant age-related changes were observed for the mean volumes of the soma, ground substance, Golgi, DB, and SN (RER). Positive linear trends were found for the mean volumes of the ground substance, Golgi, and DB; a negative linear trend was found for the SN (RER). These results indicate that rat cerebellar basket cells endure important age-related changes. The significant decrease in the SN (RER) may be responsible for a reduction in the rate of protein synthesis. Additionally, it may be implicated in a cascade of events leading to cell damage due to the excitotoxic activity of glutamate, which could interfere in the functioning of the complex cerebellar neuronal network.

Aging↗
PubMed2001

Customized bicarbonate buffered dialysate and replacement solutions for continuous renal replacement therapies: effect of crystallization on the measured levels of electrolytes and buffer.

The aim of this study was to investigate the impact of the addition of calcium to bicarbonate solutions for continuous renal replacement therapy (CRRT). We tested single bag (bicarbonate and calcium mixed 24 h before testing) and double bag solutions (mixed immediately before) with and without the addition of 4 mEq/L of acetate. Prescribed calcium varied from 0 to 5 mEq/L. All test solutions containing calcium showed crystallization at light microscopy. The double bag solutions decreased but did not prevent crystallization. The addition of acetate did not interfere with crystallization. Crystallization, as measured by the weight of the crystals after filtration of the solutions, showed a significant positive correlation with the calcium deficit (prescribed minus measured) and with partial pressure of carbon dioxide. The measured level of calcium was lower than expected and correlated with crystallization. Our results suggest that the use of bicarbonate solutions containing calcium as replacement fluids for CRRT is a potentially unsafe procedure.

Bicarbonates↗
PubMed2001

Stereologic characterization of bovine (Bos taurus) cumulus-oocyte complexes aspirated from small antral follicles during the diestrous phase.

Bovine ovarian cumulus-oocyte complexes (COCs) are used for in vitro maturation and fertilization after selection by size and morphology, but their developmental potential remains low. Stereology could provide more objective criteria for selecting the most competent complexes, but its application is lacking in cattle. COCs from small (1-4 mm) antral follicles were aspirated from diestrous ovaries of Holstein-Friesian cows, fixed in glutaraldehyde, randomly embedded in glycol-methacrylate, and sectioned at 20 microm. The unbiased nucleator principle was used for estimating the mean volumes of complexes, oocytes, cumulus cells, and nuclei of oocytes and cumulus cells. The thickness of the zona pellucida and the relative numerical percentages of the several morphologic types of cumulus cells were also evaluated. The optical disector procedure was used for cumulus cell sampling. Volume estimation based on a real physical unique point did not differ from those based on a particular point among many or on a virtual central point, and the mean cumulus cell volume was estimated by using the single section bearing the unique reference point. Quantitative data showed that COCs appear heterogeneous for all studied parameters and that the cumulus mass contains three different cell populations.

Animals↗
PubMed2001

The hepatocytes of the brown trout (Salmo trutta f. fario): a quantitative study using design-based stereology.

A stereological study was performed on brown trout hepatocytes aiming to disclose whether there are basic gender differences when minimal levels of sex hormones exist, and also to establish a platform for both interspecific comparisons and physiological correlations. We used the so-called "design-based stereology" (with no shape, size or orientation assumptions) and also some new related statistics. Two-year-old brown trout were collected in April, and the livers were fixed by perfusion. From liver slicing to microscopical field selection, systematic sampling was used. Stereology was applied at light and electron microscopy. Target parameters were the relative and total hepatocyte number, the mean individual hepatocyte volume and surface, and also both relative and total volumes, and surfaces, either of organelles or of cell compartments. Observed variability was usually high, but the precision of estimates was proved to be globally adequate facing the true biological variation amongst specimens. Females had more hepatocytes per liver (1.79x10(9) vs. 1.12x10(9)). Considering the individual hepatocytes, whereas no gender differences were detected in the cell volume, males had higher values of nuclear volume (199 vs. 151 microm3) and surface (170 vs. 131 microm2), endoplasmic reticulum volume (1,300 vs. 824 microm3), and microvilli volume (82 vs. 54 microm3) and surface (1,445 vs. 975 microm2). However, when dealing with quantities per liver, gender differences were found only in the volumes of dense bodies (56 vs. 97 mm3) and of residual cytoplasm (169 vs. 341 mm3)--both volumes were higher in females. Functional implications of data are discussed, namely that females seem to have basic structural traits for coping with the later demands of breeding. Data also support that structural remodelling of hepatocytes occurs after breeding, urging to pursue seasonal studies (namely on lysosomes). We advanced the hypothesis that genders differ in microvilli surface just to maintain an optimal physiological surface-to-volume ratio. Interspecific similarities and differences were disclosed. For example, the number of hepatocytes/cm3 of parenchyma of brown trout was much lower than those reported in rainbow trout, but in both trouts females seem to have an higher cell number. In addition, when comparing the size of hepatocytes of brown trout with that from other fish and mammals it was suggested that major interspecific differences exist.

Animals↗
PubMed2000

Hemostatic disturbances in patients with systemic inflammatory response syndrome (SIRS) and associated acute renal failure (ARF).

Endothelial damage plays a central role in the development of an SIRS-related Multiple Organ Dysfunction Syndrome (MODS) as a consequence of the establishment of a hemostatic imbalance between coagulation and fibrinolysis systems. Until now, sepsis is the SIRS model that has been most studied. The aim of this study was to assess the endothelial damage and the hemostatic imbalance in early stages of an SIRS of different origins, and to study if there are any differences in these disturbances between infectious and noninfectious SIRS. The endothelial damage and hemostatic changes were studied in 40 patients with SIRS (with less than 12 h of evolution) and an acute renal failure. Infectious SIRS was diagnosed in 19 cases and noninfectious SIRS in the remaining 21 patients. Patients with SIRS presented significantly higher values (p<0.001) for factors related to endothelial damage [von Willebrand factor (vWF), thrombomodulin, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor type 1 (PAI-1) antigen], hypercoagulability [prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complexes (TAT)], and fibrinolysis (D-dimer and PAI activity) with respect to the control group. However, although the group with infectious SIRS presented higher values for all the factors except for the t-PA and D-dimer with respect to SIRS of other origins, none of these differences reached statistical significance (p>0.05). Our data show that patients with SIRS and associated acute renal failure, irrespective of the origin (infectious or noninfectious), show signs of intense endothelial damage and hypercoagulability throughout the process.

Acute Disease↗
PubMed2000

Virus-expressed, recombinant single-chain antibody blocks sporozoite infection of salivary glands in Plasmodium gallinaceum-infected Aedes aegypti.

Transgenic mosquitoes resistant to malaria parasites are being developed to test the hypothesis that they may be used to control disease transmission. We have developed an effector portion of an antiparasite gene that can be used to test malaria resistance in transgenic mosquitoes. Mouse monoclonal antibodies that recognize the circumsporozoite protein of Plasmodium gallinaceum can block sporozoite invasion of Aedes aegypti salivary glands. An anti-circumsporozoite monoclonal antibody, N2H6D5, whose corresponding heavy- and light-chain gene variable regions were engineered as a single-chain antibody construct, binds to P. gallinaceum sporozoites and prevents infection of Ae. aegypti salivary glands when expressed from a Sindbis virus. Mean intensities of sporozoite infections of salivary glands in mosquitoes expressing N2scFv were reduced as much as 99.9% when compared to controls.

Aedes↗