Biomedical subjects

O F Bueno

Publications and source records attributed to O F Bueno.

At least 19 recordsLinked to original sources

PubMed2003

Cognitive performance, SPECT, and blood viscosity in elderly non-demented people using Ginkgo biloba.

The aging process is associated with several cognitive alterations. This study looks at the effects of taking dried extract of Ginkgo biloba, which has been used in several countries in an attempt to minimize these effects. The subjects were 48 men aged 60 - 70 matched between control and experimental groups for educational level. Evaluation was based on a number of neuropsychological tests in an attempt to cover the largest possible number of functions including Single Photon Emission Computer Tomography (SPECT) and measures of blood viscosity. The study was run on a double-blind basis with placebo and Ginkgo biloba groups evaluated over a period of 8 months. After treatment, the experimental group showed a reduction in blood viscosity, improved cerebral perfusion in specific areas and improved global cognitive functioning. The control group showed the opposite - higher blood viscosity, a reduction in cerebral perfusion (in specific areas), and cognitive deterioration in different functions. Although the mechanisms by which Ginkgo biloba may contribute to overall enhancement of the parameters evaluated have not been specified, this plant extract certainly appears to be effective in the treatment of cognitive deficits in older people. Further research into its use is called for on the basis of the results obtained here.

Aged↗

PubMed2001

Targeted inhibition of calcineurin attenuates cardiac hypertrophy in vivo.

The Ca(2+)-calmodulin-activated Ser/Thr protein phosphatase calcineurin and the downstream transcriptional effectors of calcineurin, nuclear factor of activated T cells, have been implicated in the hypertrophic response of the myocardium. Recently, the calcineurin inhibitory agents cyclosporine A and FK506 have been extensively used to evaluate the importance of this signaling pathway in rodent models of cardiac hypertrophy. However, pharmacologic approaches have rendered equivocal results necessitating more specific or genetic-based inhibitory strategies. In this regard, we have generated Tg mice expressing the calcineurin inhibitory domains of Cain/Cabin-1 and A-kinase anchoring protein 79 specifically in the heart. DeltaCain and DeltaA-kinase-anchoring protein Tg mice demonstrated reduced cardiac calcineurin activity and reduced hypertrophy in response to catecholamine infusion or pressure overload. In a second approach, adenoviral-mediated gene transfer of DeltaCain was performed in the adult rat myocardium to evaluate the effectiveness of an acute intervention and any potential species dependency. DeltaCain adenoviral gene transfer inhibited cardiac calcineurin activity and reduced hypertrophy in response to pressure overload without reducing aortic pressure. These results provide genetic evidence implicating calcineurin as an important mediator of the cardiac hypertrophic response in vivo.

A Kinase Anchor Proteins↗

PubMed2001

The dual-specificity phosphatase MKP-1 limits the cardiac hypertrophic response in vitro and in vivo.

Mitogen-activated protein kinase (MAPK) signaling pathways are important regulators of cell growth, proliferation, and stress responsiveness. A family of dual-specificity MAP kinase phosphatases (MKPs) act as critical counteracting factors that directly regulate the magnitude and duration of p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) activation. Here we show that constitutive expression of MKP-1 in cultured primary cardiomyocytes using adenovirus-mediated gene transfer blocked the activation of p38, JNK1/2, and ERK1/2 and prevented agonist-induced hypertrophy. Transgenic mice expressing physiological levels of MKP-1 in the heart showed (1) no activation of p38, JNK1/2, or ERK1/2; (2) diminished developmental myocardial growth; and (3) attenuated hypertrophy in response to aortic banding and catecholamine infusion. These results provide further evidence implicating MAPK signaling factors as obligate regulators of cardiac growth and hypertrophy and demonstrate the importance of dual-specificity phosphatases as counterbalancing regulatory factors in the heart.

Adenoviridae↗

PubMed2001

The transcription factor GATA4 is activated by extracellular signal-regulated kinase 1- and 2-mediated phosphorylation of serine 105 in cardiomyocytes.

The zinc finger-containing transcription factor GATA4 has been implicated as a critical regulator of multiple cardiac-expressed genes as well as a regulator of inducible gene expression in response to hypertrophic stimulation. Here we demonstrate that GATA4 is itself regulated by the mitogen-activated protein kinase signaling cascade through direct phosphorylation. Site-directed mutagenesis and phospho-specific GATA4 antiserum revealed serine 105 as the primary site involved in agonist-induced phosphorylation of GATA4. Infection of cultured cardiomyocytes with an activated MEK1-expressing adenovirus induced robust phosphorylation of serine 105 in GATA4, while a dominant-negative MEK1-expressing adenovirus blocked agonist-induced phosphorylation of serine 105, implicating extracellular signal-regulated kinase (ERK) as a GATA4 kinase. Indeed, bacterially purified ERK2 protein directly phosphorylated purified GATA4 at serine 105 in vitro. Phosphorylation of serine 105 enhanced the transcriptional potency of GATA4, which was sensitive to U0126 (MEK1 inhibitor) but not SB202190 (p38 inhibitor). Phosphorylation of serine 105 also modestly enhanced the DNA binding activity of bacterially purified GATA4. Finally, induction of cardiomyocyte hypertrophy with an activated MEK1-expressing adenovirus was blocked with a dominant-negative GATA4-engrailed-expressing adenovirus. These results suggest a molecular pathway whereby MEK1-ERK1/2 signaling regulates cardiomyocyte hypertrophic growth through the transcription factor GATA4 by direct phosphorylation of serine 105, which enhances DNA binding and transcriptional activation.

Adenoviridae↗

PubMed2001

A set of 400 pictures standardised for Portuguese: norms for name agreement, familiarity and visual complexity for children and adults.

The present article provides normative measures for 400 pictured objects (Cycowicz et al., 1997) viewed by Portuguese speaking Brazilian University students and 5-7 year-old children. Name agreement, familiarity and visual complexity ratings were obtained. These variables have been shown to be important for the selection of adequate stimuli for cognitive studies. Children's name agreement was lower than that of adults. The children also failed to provide adequate modal names for 103 concepts, rated drawings as less familiar and less complex, and chose shorter names for pictures. The differences in ratings between adults and children were higher than those observed in the literature employing smaller picture sets. The pattern of correlations among measures observed in the present study was consistent with previous reports, supporting the usefulness of the 400 picture set as a tool for cognitive research in different cultures and ages.

Adult↗

PubMed2000

The MEK1-ERK1/2 signaling pathway promotes compensated cardiac hypertrophy in transgenic mice.

Members of the mitogen-activated protein kinase (MAPK) cascade such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 are implicated as important regulators of cardiomyocyte hypertrophic growth in culture. However, the role that individual MAPK pathways play in vivo has not been extensively evaluated. Here we generated nine transgenic mouse lines with cardiac-restricted expression of an activated MEK1 cDNA in the heart. MEK1 transgenic mice demonstrated concentric hypertrophy without signs of cardiomyopathy or lethality up to 12 months of age. MEK1 transgenic mice showed a dramatic increase in cardiac function, as measured by echocardiography and isolated working heart preparation, without signs of decompensation over time. MEK1 transgenic mice and MEK1 adenovirus-infected neonatal cardiomyocytes each demonstrated ERK1/2, but not p38 or JNK, activation. MEK1 transgenic mice and MEK1 adenovirus-infected cultured cardiomyocytes were also partially resistant to apoptotic stimuli. The results of the present study indicate that the MEK1-ERK1/2 signaling pathway stimulates a physiologic hypertrophy response associated with augmented cardiac function and partial resistance to apoptotsis.

Actinin↗

PubMed2000

Cholinergic modulation of inhibitory avoidance impairment induced by paradoxical sleep deprivation.

1. Male Wistar rats were submitted to paradoxical sleep deprivation for 96 hr by a modified multiple platform technique. 2. Training of step-through inhibitory avoidance was performed immediately after the last day of paradoxical sleep deprivation. Twenty-four hr after training the animals were submitted to the retention test. 3. In Experiment 1, pilocarpine (4 mg/kg, i.p.) or atropine (4 mg/kg, i.p.) were administered daily during the paradoxical sleep deprivation period. Pilocarpine, but not atropine, reversed the impairment induced by PS deprivation. 4. In Experiment 2, pilocarpine (4, 8 and 12 mg/kg, i.p.) was injected 1 hr before training in order to verify if the reversal of memory impairment was an effect secondary to residual enhanced blood levels of pilocarpine during training. Acute treatment with pilocarpine, in any dose, did not reverse the impairment produced by paradoxical sleep deprivation 5. Activation of the cholinergic system during the period of deprivation is able to prevent memory deficits induced by paradoxical sleep deprivation.

Animals↗

PubMed2000

A double-dissociation of behavioural and event-related potential effects of two benzodiazepines with similar potencies.

This study was designed to explore the role of benzodiazepine affinity to benzodiazepine binding site on acute psychomotor, subjective and memory effects, as well as auditory Event Related Potential (ERP) latencies, in healthy volunteers. Two benzodiazepines with similar affinity to benzodiazepine binding sites, or potency, were compared: the atypical compound lorazepam (2.0 mg), which has been reported to impair priming, and a standard benzodiazepine, flunitrazepam (0.6 mg, 0.8 mg, 1.0 mg). The study followed a placebo-controlled, double-blind, parallel-group design. Sixty subjects completed a test battery before treatment and at theoretical peak plasma concentration of drugs. Lorazepam and 1.0 mg of flunitrazepam led to comparable alterations on psychomotor, subjective and auditory episodic memory measures. A double-dissociation was found for lorazepam and the equipotent dose of flunitrazepam (1.0 mg): lorazepam was more deleterious than flunitrazepam in time taken to identify fragmented shapes. Lorazepam also impaired direct and indirect stem-completion in comparison to placebo, but this effect was abolished when time to identify shapes was used as a covariate. By contrast, 1.0 mg of flunitrazepam prolonged auditory ERP latencies to a greater extent than lorazepam. High affinity to the benzodiazepine binding sites does not seem to explain the consistent lorazepam-induced impairment of indirect stem-completion. Differences in impairment profile between the benzodiazepines employed may relate to the modality (visual or not) of the tasks used.

Adolescent↗

PubMed2000

[Procedures to improve daily activities performance in individuals with cerebral anoxia: case report].

OBJECTIVE: To present a rehabilitation case study; procedures to improve the performance on daily activities were used by the caregiver. PATIENT: Cerebral anoxia due to cardiac arrest. He presented memory deficits for both visual and verbal material, temporal disorientation, abulia, psychomotor slowing and bradypsychism. METHODS: daily activities were developed in fixed hours; calendar was presented 3 times a day; daily walks were performed; self-care activities were performed by the patient with short verbal commands and cues from the caregiver. RESULTS: We observed improvement on initiative and autonomy for daily activities, attention, temporal orientation and bradypsychism. There was also reduction on response time. CONCLUSIONS: Behavioral control strategies result on improvement for patients and their family although limit their routine. Behavioral control strategy promotes learning through the preserved implicit memory mechanism and results on enhancement at patient's autonomy at home.

Activities of Daily Living↗

PubMed2000

[Implicit memory and its contribution to the rehabilitation of an amnesic patient: case report].

Even severe amnesic patients usually are able to learn new information using implicit memory strategies. In the present study we describe our experience in the rehabilitation of an amnesic patient who had suffered cerebral anoxia. He was taught to use a computer text editor, enabling him to sheltered work. The training program lasted 14 weeks and was based on errorless learning and drilling practice techniques. The patient succeeded in all tasks, even though he could not remember accurately the training sessions. These results meet previous studies which point out that interaction between implicit and residual explicit memory can provide a basis new learning in amnesic patients. The domain-specific knowledge acquisition is demonstrating effectiveness in neuropsychological rehabilitation of brain injured patients.

Adult↗

PubMed1999

Cognitive profile of patients with relapsing remitting multiple sclerosis.

Multiple sclerosis (MS) is a common disease in Western countries of temperate/cold climate, but in tropical countries an increasing number of cases have been diagnosticated. Moved by the lack of information about cognitive dysfunction of Brazilian MS patients, the present study attempted to describe features of neuropsychological alterations in patients with relapsing remitting MS living in the city of São Paulo. They were compared to healthy volunteers, matched for age and education. In the absence of global intellectual deterioration, the patients had a deficit: a) in learning and verbal long-term memory tasks and in visual long-term memory of complex figure; b) in timed tasks, accounted for by a slowness of mental processes; c) in tasks with a motor component. Tendency to depression was observed; anxiety levels were normal.

Adolescent↗

PubMed1998

Activation of protein kinase C induces gamma-aminobutyric acid type A receptor internalization in Xenopus oocytes.

The inhibition of gamma-aminobutyric acid (GABA)-gated chloride currents by the protein kinase C (PKC) activator 4beta-phorbol 12-myristate 13-acetate (PMA) was investigated using recombinant human GABAA receptors expressed in Xenopus oocytes. PMA (5 nM) reduced the GABA response in oocytes expressing the alpha1 beta2 gamma2L receptor construct, as measured by the two-electrode voltage-clamp method. GABA responses declined to approximately 25% of their pretreatment value within 45 min. GABA responses in oocytes expressing a receptor construct from which the known PKC phosphorylation sites were absent, alpha1 beta2(S410A), were comparably inhibited. Phorbol 12-monomyristate (PMM; 5 nM), which does not activate PKC, did not alter the GABA response in either construct, while the PKC inhibitor calphostin C (0.5 microM) prevented the PMA effect. To further investigate PMA inhibition of the GABA response, a GABAA receptor alpha1 subunit/green fluorescent protein (GFP) chimera (alpha1GFP) was used to visualize GABAA receptor distribution. Similar to the wild type constructs, PMA robustly decreased GABA responses in oocytes expressing alpha1GFP beta2 gamma2L and alpha1GFP beta2(S410A) receptor constructs. Following PMA treatment, GFP fluorescence in the oocyte plasma membrane was decreased to approximately 45% of the pretreatment values indicating GABAA receptor internalization. This effect of PMA was prevented by calphostin C and was not produced by PMM. Experiments with bd24, a monoclonal antibody which recognizes an extracellular epitope of the alpha1 subunit, were used to demonstrate that PMA, but not PMM, decreases alpha1 subunit immunoreactivity in the plasma membrane of intact oocytes expressing the alpha1 beta2 gamma2L construct, thus confirming the results obtained with the chimeric receptor. It is concluded that, in Xenopus oocytes, PMA induces an internalization of the GABAA receptor through PKC-mediated phosphorylation of an unidentified protein(s) and that this contributes to the decrease in electrophysiological responses to GABA following PKC activation.

Animals↗

PubMed1998

Functional characterization and visualization of a GABAA receptor-GFP chimera expressed in Xenopus oocytes.

The GABAA receptor is a ligand-gated chloride channel belonging to the superfamily of ligand-gated ion channels of which the nicotinic acetylcholine (nACh) receptor is prototypic. In the central nervous system the GABAA receptor mediates fast neuronal inhibition. To facilitate the study of this receptor, a GABAA receptor-green fluorescent protein (GABAAR-GFP) chimera was constructed by fusing green fluorescent protein (GFP) to the C-terminus region of the GABAA receptor alpha1 subunit. When expressed in Xenopus oocytes, this chimera responded in a manner indistinguishable from the wild-type GABAA receptor with respect to agonist potency, receptor desensitization, allosteric modulation, rectification, and ion selectivity of the channel. The addition of GFP to the GABAA receptor alpha1 subunit did not appear to alter the assembly or efficiency of expression of the GABAA receptor complex. The GABAAR-GFP chimera generated a strong fluorescent signal that was restricted to the animal pole of the oocyte plasma membrane. This signal was readily detectable using either epifluorescence or laser confocal microscopy. To confirm the extracellular location of the GFP portion of the chimera, non-permeabilized oocytes were immunolabeled with an anti-GFP antibody. Fluorescence microscopy showed that GFP was located extracellularly since it was accessible to the GFP antibody. These results confirm the predicted extracellular location of the C-terminus of the GABAA receptor alpha1 subunit and also demonstrate that GFP retains its fluorescent property when expressed extracellularly. The usefulness of the GABAAR-GFP chimera in receptor trafficking was investigated using non-hydrolyzable GTP analogues since GTP binding proteins participate in protein transport in oocytes. Microinjections of GTP-gamma-S but not GDP-beta-S reduced both GABA-gated chloride currents and cell surface GFP fluorescence in oocytes expressing the GABAAR-GFP chimera indicating that the chimera undergoes internalization upon stimulation of oocyte GTP-binding proteins. The results of the present study show that the GABAAR-GFP chimera is functionally similar to the wild-type GABAA receptor and can be used to study receptor trafficking in living cells. This is the first demonstration of a ligand-gated ion channel-GFP chimera for an ion channel belonging to this superfamily and also is the first example of the fusion of GFP to an extracellular domain of an integral membrane protein.

Anesthetics↗

PubMed1998

Colchicine inhibits GABA(A) receptors independently of microtubule depolymerization.

Colchicine is a microtubule depolymerizing agent used extensively in the study of cytoskeleton-dependent cell functions. In studying the possible functional interaction between the GABA(A) receptor and the cytoskeleton, we found that colchicine inhibits GABA(A) receptor function by mechanisms independent of microtubule depolymerization. Human GABA(A) receptor alpha1beta2gamma2L subunits were co-expressed in Xenopus oocytes and the effects of colchicine on GABA(A) receptor function was assessed using the two-electrode voltage-clamp technique. Co-application of GABA (10 microM) with colchicine (100 microM) resulted in a 59.9% inhibition of GABA-gated chloride currents. This effect was instantaneous in onset with no pre-incubation required and reversed within seconds. Other depolymerizing agents, such as nocodazole (20 microM) and vinblastine (200 microM), did not affect GABA(A) receptor function using the same co-application protocol used with colchicine. The polymerizing agent taxol (10-50 microM) did not affect colchicine inhibition of the GABA responses and did not itself alter GABA-gated chloride currents. The inhibitory effect of colchicine was present under conditions in which the oocyte microtubules had been depolymerized by cold temperature. These results indicate that colchicine inhibits the GABA(A) receptor via mechanisms unrelated to microtubule depolymerization. To further examine the inhibitory effect of colchicine on the GABA response, GABA (10-3000 microM) concentration-response curves were performed in the absence or presence of various concentrations of colchicine (30-300 microM). In the presence of colchicine, the GABA concentration-response curve was shifted to the right in a parallel fashion. A Schild plot of this data yielded a linear slope indicating that colchicine acts as a competitive antagonist at the GABA binding site. We conclude that colchicine is a competitive antagonist at the GABA(A) receptor and that studies using colchicine to examine the functional interaction between GABA(A) receptors and microtubules should be interpreted with caution.

Animals↗

PubMed1998

Preliminary adaptation into Portuguese of a standardised picture set for the use in research and neuropsychological assessment.

Pictorial stimuli and words have been widely used to evaluate mnemonic processes in clinical settings, neuropsychological investigations, as well as in studies on the mechanisms underlying the phenomena of memory. However, there seem to be few studies of standardisation of pictures for research in this field. The present paper aimed at adapting the use of a set of pictures standardised for English speaking subjects for Portuguese speakers. Name agreement of 150 pictures was assessed in 100 high-school students. Ninety pictures were found to present the same name for over 90 subjects. Results yield data that may help create more controlled tests for the study of memory for pictorial stimuli in Brazil.

Adolescent↗

PubMed1998

Anterograde effects of a single electroconvulsive shock on inhibitory avoidance and on cued fear conditioning.

A single electroconvulsive shock (ECS) or a sham ECS was administered to male 3-4-month-old Wistar rats 1, 2, and 4 h before training in an inhibitory avoidance test and in cued classical fear conditioning (measured by means of freezing time in a new environment). ECS impaired inhibitory avoidance at all times and, at 1 or 2 h before training, reduced freezing time before and after re-presentation of the ECS. These results are interpreted as a transient conditioned stimulus (CS)-induced anxiolytic or analgesic effect lasting about 2 h after a single treatment, in addition to the known amnesic effect of the stimulus. This suggests that the effect of anterograde learning impairment is demonstrated unequivocally only when the analgesic/anxiolytic effect is over (about 4 h after ECS administration) and that this impairment of learning is selective, affecting inhibitory avoidance but not classical fear conditioning to a discrete stimulus.

Amnesia↗

PubMed1997

Strategies used by hippocampal- and caudate-putamen-lesioned rats in a learning task.

In rats, hippocampal lesions result in impairment of spatial navigation, although other learning abilities remain unaltered. When learning a left/right discrimination task, rats can use a spatial strategy (with external maze landmarks-Situation 1) or are forced to use an egocentric strategy (without external or internal maze cues-Situation 2). Little is known about the extrahippocampal systems involved in the utilization of egocentric strategy. It is suggested that striatum could play an important role in the learning abilities that are spared after hippocampal lesion. The aim of our study was to investigate which strategy is used by rats bearing hippocampal or caudate-putamen lesions in the acquisition of a left/right discrimination task in an elevated T-maze in both Situations 1 and 2. We also investigated the effect of each lesion on the reversal of discrimination in both situations. Acquisition was not altered in any of the situations; however, a transfer test showed that hippocampal-lesioned rats used a different strategy (egocentric) from control animals (spatial) in Situation 1. In addition, reversal of the discrimination was impaired in Situation 2. Caudate-putamen lesion produced a transient effect on reversal of discrimination only in the egocentric task (Situation 2), but did not impair acquisition of the task in either situation, thus suggesting that the animals were able to use either strategy.

Animals↗

PubMed1994

Long-lasting effects of chronic ethanol administration on the activity of antioxidant enzymes.

The aim of this study was to investigate the long-lasting effects of prolonged administration of ethanol doses on oxidative processes of aged rats. We determined the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in erythrocytes of rats 15, 20, and 24 months old treated with an average daily dose of 1.5 g/Kg of ethanol or saline administered intraperitoneally for 13 weeks and after a 2 month period of withdrawal from treatment. The activity of all three enzymes decreased significantly with aging in the controls, while no age-related changes were found among treated rats. These findings are important since they are the first to show a long-lasting toxic effect of low ethanol doses observed in association with the aging process.

Aging↗