Biomedical subjects

A L Rodrigues

Publications and source records attributed to A L Rodrigues.

At least 19 recordsLinked to original sources

PubMed2006

Safety and pharmacokinetics of an intravitreal biodegradable implant of dexamethasone acetate in rabbit eyes.

The treatment of vitreoretinal diseases is limited and, nowadays, new drug delivery approaches have been reported in order to increase drug bioavailability. The objective of the current study was to determine the pharmacokinetic profile of a biodegradable dexamethasone acetate implant inserted into the vitreous of rabbits and to evaluate its potential signs of toxicity to the rabbits' eyes. The results showed that the intravitreous drug concentration remained within the therapeutic range along the 8-week period of evaluation. The system under study was not toxic to the normal rabbit retina, and no significant increase in intraocular pressure was observed.

Absorbable Implants↗

PubMed2006

Influence of fluoride-releasing restorative material on root dentine secondary caries in situ.

The usefulness of fluoride-releasing restorations in secondary caries prevention may be questioned because of the presence of other common sources of fluoride and because of ageing of the restorations. This study tested the hypothesis that glass-ionomer cement restorations, either aged or unaged, do not prevent secondary root caries, when fluoride dentifrice is frequently used. Sixteen volunteers wore palatal appliances in two phases of 14 days, according to a 2 x 2 crossover design. In each phase the appliance was loaded with bovine root dentine slabs restored with either glass-ionomer or resin composite, either aged or unaged. Specimens were exposed to cariogenic challenge 4 times/day and to fluoridated dentifrice 3 times/day. The fluoride content in the biofilm (FB) formed on slabs and the mineral loss (DeltaZ) around the restorations were analysed. No differences were found between restorative materials regarding the FB and the DeltaZ, for either aged (p = 0.792 and p = 0.645, respectively) or unaged (p = 1.00 and p = 0.278, respectively) groups. Under the cariogenic and fluoride dentifrice exposure conditions of this study, the glass-ionomer restoration, either aged or unaged, did not provide additional protection against secondary root caries.

Animals↗

PubMed2004

CaV 3.1 and CaV 3.3 account for T-type Ca2+ current in GH3 cells.

T-type Ca2+ channels are important for cell signaling by a variety of cells. We report here the electrophysiological and molecular characteristics of the whole-cell Ca2+ current in GH3 clonal pituitary cells. The current inactivation at 0 mV was described by a single exponential function with a time constant of 18.32 +/- 1.87 ms (N = 16). The I-V relationship measured with Ca2+ as a charge carrier was shifted to the left when we applied a conditioning pre-pulse of up to -120 mV, indicating that a low voltage-activated current may be present in GH3 cells. Transient currents were first activated at -50 mV and peaked around -20 mV. The half-maximal voltage activation and the slope factors for the two conditions are -35.02 +/- 2.4 and 6.7 +/- 0.3 mV (pre-pulse of -120 mV, N = 15), and -27.0 +/- 0.97 and 7.5 +/- 0.7 mV (pre-pulse of -40 mV, N = 9). The 8-mV shift in the activation mid-point was statistically significant (P < 0.05). The tail currents decayed bi-exponentially suggesting two different T-type Ca2+ channel populations. RT-PCR revealed the presence of alpha1G (CaV3.1) and alpha1I (CaV3.3) T-type Ca2+ channel mRNA transcripts.

Calcium Channels, T-Type↗

PubMed2003

Impairment of inflammatory response in adult rats submitted to maternal undernutrition during early lactation: role of insulin and glucocorticoid.

OBJECTIVE: Early nutritional environment may program permanent metabolic alterations, predisposing to later diseases. We have investigated the interference of maternal malnutrition during lactation with the development of acute inflammation in adult rats. MATERIALS AND METHODS: Adult rats, offspring of dams fed with either protein-free diet (UN group) or 22% protein diet (C group) during the first 10 days of lactation, were submitted to pleurisy with carrageenan (500 microg/cavity). Pleural edema, neutrophil migration and ICAM expression, were evaluated 4 h after and correlated with alterations in plasma insulin and corticosterone. Leukocyte-endothelium interactions were evaluated by intravital microscopy 1 h after inflammation. RESULTS: Compared to controls, UN rats showed a decrease in pleural edema formation (50%), neutrophil migration (50%), endothelial ICAM-1 expression on pulmonary tissue, and impairment in leukocyte adhesion (50%) and migration (80%) through endothelium. Circulating insulin was lower (42%) and corticosterone was higher (34%) in UN, compared to controls. Pre-treatment of UN with insulin (5 IU/day) or RU486 (20 mg/kg/day), inhibitor of glucocorticoid receptor, restored leukocyte functions and ICAM-1 expression. CONCLUSION: Postnatal maternal malnutrition, programming for permanent alterations in insulin and glucocorticoid secretion in progeny, that were unable to properly mount an inflammatory response, probably predisposes to chronic diseases in adult life.

Animals↗

PubMed2003

Analysis of surface roughness of glass-ionomer cements and compomer.

The purpose of this study was to evaluate the surface roughness of two glass-ionomer cements (Vitremer and Chelon-Fil), and one compomer (Dyract) when submitted to different finishing/polishing procedures at different times. A hundred 80-sample discs were made of each material and randomly divided into six finishing/polishing groups: mylar strip (control); Sof-Lex discs; diamond burs; diamond burs/Sof-Lex discs; 30-fluted carbide bur; 30-fluted carbide bur/Sof-Lex discs. These procedures were carried out immediately after preparation of the samples, after 24 and 168 h. Average surface roughness (Ra) was measured with a profilometer and the values were compared using anova (P < 0.05). The smoothest surface for all materials was obtained when cured in contact with the mylar strip. All other tested products increased surface roughness of restorative materials, but Sof-lex discs lead to better results. The worst results were verified with diamond burs. The finishing/polishing procedures, when performed immediately, can improve the roughness of glass-ionomer cements but not of the compomer tested.

Analysis of Variance↗

PubMed2002

In situ microhardness evaluation of glass--ionomer/composite resin hybrid materials at different post-irradiation times.

The purpose of this paper was to evaluate in situ the microhardness of a composite resin, two resin-modified glass-ionomers and two polyacid-modified composite resins at different post-irradiation times. The materials analysed were: Z 100/3M (Z1); Fuji II LC/GC Corporation (Fu); Vitremer/3M (Vi); Freedom/SDI (Fr); and Dyract/Dentsply (Dy). Palatal intra-oral acrylic resin appliances were made for each of the 24 volunteers in the experiment. In each appliance, a specimen of each material was fixed. Microhardness tests were performed at 30 min, 1, 2, 4, 8, 24 and 48 h, 7, 10, 14, 17 and 21 days after initial light-curing. The analysis of variance followed by the Tukey test showed significant differences of microhardness among all materials (Fu < Vi < Fr < Dy < Z1) up to 48 h. From the seventh to the fourteenth day, statistical differences were not found between Freedom and Dyract (Fu < Vi < Fr=Dy < Z1). On the seventeenth and twenty-first days, Vitremer, Freedom and Dyract did not present statistical differences, but differed from Fuji II LC and Z 100 (Fu < Vi=Fr=Dy < Z1). The polynomial regression showed an increase of microhardness over time for the glass-ionomers/composite resin hybrid materials, although there were differences of microhardness among these materials. There was no significant changes in microhardness levels for the composite resin over time.

Adult↗

PubMed2002

Effect of storage media upon the surface micromorphology of resin-based restorative materials.

The aim of this study was to evaluate the effect of different storage media upon the surface micromorphology of resin-based restoratives. One resin-modified glass-ionomer (Fuji II LC Improved), one polyacid-modified composite resin (Dyract AP), one microfilled composite resin (Durafill VS), and one hybrid composite resin (Filtek Z250) were tested. For each material, 45 standardized cylindrical specimens were randomly made. After 24 h, samples were finished and polished, and their surface roughness measured to obtain Ra (micro m) baseline values (Bv). Fifteen specimens of each material were then stored at 37 +/- 1 degrees C, for 24 h, either in distilled deionized water or in artificial saliva, or else subjected to a pH-cycling regimen. At the end of 10 days of storage, final readings (Fv) of surface roughness were obtained. The Analysis of Covariance (alpha=0.05), considering the covariate Bv showed a significant interaction between restorative materials and storage media (P value=0.0000). Multiple comparison Tukey's test revealed that the surface roughness of resin-based restoratives subjected to a pH-cycling model was significantly higher compared with both distilled deionized water and artificial saliva. Micromorphological changes were noticed in a situation of acid challenge.

Acids↗

PubMed2002

Electromyographic study of the masseter muscle in individuals with Class II malocclusion.

The objective of this work was to study the action of the masseter muscle through electromyography and to analyze the difference of action potential generated by several pre-established jaw movements in individuals with Class II malocclusion. It was studied nine young individuals from both sexes, with ages ranging from 17 to 35, with no history of orthodontic treatment and/or having some kind of alteration in the temporomandibular joint (T.M.J.). In order to collect the electromyographic signs we have used a TECA TE-4 Electromygraph and surface electrodes type Beckman. The data were submitted to nonparametric statistical analysis by Friedman test. The response variables left occlusive contact, free protraction, protraction with occlusive contact, incisor mastication, right molar mastication and forced central occlusion movements showed significant outcomes. Thus we have concluded that as the occlusive balance suffers alterations, the malocclusions become predominant and the masseter muscle undergoes functional and structural modifications.

Action Potentials↗

PubMed2001

Influence of cross-head speed on resin-dentin shear bond strength.

OBJECTIVE: To evaluate the influence of different cross-head speeds on shear bond strength test on the dentin surface. METHODS: One hundred and twenty extracted bovine incisors were embedded in polystyrene resin. The specimens were prepared by wet grinding with 320-, 400- and 600-grit Al2O3 paper exposing dentin. After the application of the adhesive system Single Bond (3M) to etched dentin, the composite resin Z-100 (3M) was applied and light cured. The specimens were randomly assigned to four groups (n=30). The shear bond strength tests were performed with an EMIC DL 500 universal testing machine at four different cross-head speeds: 0.50 (A); 0.75 (B); 1.00 (C); and 5.00 mm/min (D). RESULTS: The mean values of shear bond strength in MPa (SD) were: A, 11.78 (3.91); B, 11.82 (4.78); C, 16.32 (6.45); D, 15.46 (5.94). The data were analyzed with one-way ANOVA and Tukey's test (alpha=0.05). The results indicated that A=B<C=D. The fracture pattern was evaluated by visual analysis in a stereomicroscope (25x). The percentage of fractures that occurred at the adhesive interface were: A, 92.5%; B, 91.6%; C, 70.0%; D, 47.0%. The Student's t-test to percentages (alpha=0.05) indicated that there were no significant differences among A, B and C; A and B differed from D, and there was no significant difference between C and D. SIGNIFICANCE: Different cross-head speeds may influence the shear bond strength and the fracture pattern in dentin substrate. Shear bond strength using cross-head speeds of 0.50 and 0.75 mm/min should be preferred.

Acid Etching, Dental↗

PubMed2001

Effects of lead and/or zinc exposure during the second stage of rapid postnatal brain growth on delta-aminolevulinate dehydratase and negative geotaxis of suckling rats.

Lead has been shown to produce cognitive and motor deficits in young rats that could be mediated, at least in part, by inhibition of the zinc-containing heme biosynthetic enzyme delta-aminolevulinate dehydratase (ALA-D). In the present study we investigated the effects of lead and/or zinc treatment during the second stage of rapid postnatal brain development on brain, kidney and blood ALA-D specific activity, as well as the negative geotaxis behavior of rats. Eight-day-old Wistar rats were injected intraperitoneally with saline, lead acetate (8 mg/kg) and/or zinc chloride (2 mg/kg) daily for five consecutive days. Twenty-four hours after treatment, ALA-D activity was determined in the absence and presence of DL-dithiothreitol (DTT). The negative geotaxis behavior was assessed in 9- to 13-day-old rats. Treatment with lead and/or zinc did not affect body, brain or kidney weights or brain- or kidney-to-body weight ratios of the animals. In spite of the absence of effect of any treatment on ALA-D specific activity in brain, kidney and blood, the reactivation index with DTT was higher in the groups treated with lead or lead + zinc than in the control group, in brain, kidney and blood (mean +/- SEM; brain: 33.33 +/- 4.34, 38.90 +/- 8.24, 13.67 +/- 3.41; kidney: 33.50 +/- 2.97, 37.60 +/- 2.67, 15.80 +/- 2.66; blood: 63.95 +/- 3.73, 56.43 +/- 5.93, 31.07 +/- 4.61, respectively, N = 9-11). The negative geotaxis response behavior was not affected by lead and/or zinc treatment. The results indicate that lead and/or zinc treatment during the second stage of rapid postnatal brain growth affected ALA-D, but zinc was not sufficient to protect the enzyme from the effects of lead in brain, kidney and blood.

Animals↗

PubMed2001

Mycobacterial spindle cell pseudotumor of the appendix vermiformis in a patient with aids.

Mycobacterial pseudotumor (MP) is a rare pathologic presentation of both Mycobacterium tuberculosis and non-tuberculous mycobacterial disease, hitherto reported to occur only in immunosuppressed patients with or without human immunodeficiency virus infection. This lesion shares close pathologic resemblance to certain mesenchymal neoplasms, particularly Kaposi's sarcoma (KS), from which it must be properly differentiated due to distinct prognosis and therapy. We report a case of MP obliterating the lumen of the appendix vermiformis in a 34-year-old patient who died of complications of AIDS at our hospital in Rio de Janeiro. A total of 24 cases of MP (including our patient) have been described in the literature. MP has been found especially in lymph nodes, but extranodal lesions have been described in the skin, spleen, lung, bone marrow, brain and, in our patient, the appendix vermiformis. We offer a review of the other 23 published case reports of MP in both HIV-infected and uninfected patients and discuss the pathologic features that differentiate MP from KS.

AIDS-Related Opportunistic Infections↗

PubMed2001

Microleakage of hydrophilic adhesive systems in Class V composite restorations.

PURPOSE: To investigate the microleakage of four hydrophilic adhesive systems: one "multiple-bottles" (Scotchbond Multi-Purpose Plus); two "one-bottle" (Single Bond, Stae); and one self-etching (Etch & Prime 3.0). MATERIALS AND METHODS: 120 bovine incisor teeth were divided into four groups (n = 30) and Class V cavities were prepared at the cemento-enamel junction. The cavities were restored with the adhesive systems and with Z100 composite. The teeth were thermocycled 1,000 times between 5+/-2 degrees C and 55+/-2 degrees C with a dwell time of 1 min, and then placed in a 2% methylene blue dye (pH 7.0) for 4 hrs, washed and sectioned vertically through the center of the restorations. The qualitative evaluation was made by three examiners who distributed pre-established scores (0-4) for each tooth using a stereomicroscope at x30 magnification. RESULTS: In enamel margins little microleakage was observed and the Kruskal-Wallis analysis did not show differences. In dentin margins the Kruskal-Wallis and multiple comparison analyses were applied: microleakage was significantly greater with Stae (median 3) and Scotchbond MP Plus (median 4). Single Bond (median 1) and Etch & Prime 3.0 (median 2) showed the best results in dentin margins, and the statistical analysis did not demonstrate differences in microleakage among these groups.

Animals↗

PubMed2001

Radiopacity of esthetic restorative materials compared with human tooth structure.

PURPOSE: To compare the radiopacity of 13 restorative materials, (a conventional glass-ionomer cement, three resin-modified glass-ionomer cements, six polyacid-modified resin-based composites, and three resin-based composites) to sound tooth structure. MATERIALS AND METHODS: 315 specimens were made of the restorative materials (n = 21), of 2 mm height and 4.1 mm diameter. Radiographs were taken of the specimens, together with the tooth structure sample and an aluminum step wedge. The radiopacity values of each specimen were taken using a transmission densitometer. RESULTS: ANOVA and Tukey's test (95% level of confidence) revealed that, except for a resin-based composite, a polyacid-modified resin-based composite, a resin-modified glass-ionomer cement and the conventional glass-ionomer cement, all the evaluated restorative materials were more radiopaque than the tooth structure.

Absorptiometry, Photon↗

PubMed2000

Evidence for dual effects of nitric oxide in the forced swimming test and in the tail suspension test in mice.

L-Arginine (L-Arg), a substrate for nitric oxide synthase (NOS) at a dose of 250-500 mg/kg, i.p., significantly reduced the duration of immobility both in the forced swimming test (FST) and in the tail suspension test (TST), two models of depression in mice, without changing locomotion in an open field. Paradoxically, a similar effect was observed with the administration of N(G)-nitro-L-arginine (L-NNA) (0.3-10 mg/kg, i.p.), an inhibitor of NOS. However, higher doses of L-Arg (750-1000 mg/kg) and L-NNA (30 mg/kg) did not produce any anti-immobility effect in FST and TST. The inactive isomers D-Arg (100-1000 mg/kg, i.p.) and D-NNA (0.3-30 mg/kg, i.p.) did not affect immobility duration in either the FST and TST. Preadministration of L-NNA (30 mg/kg, i.p.), but not of D-NNA completely blocked the anti-immobility effect of L-Arg (500 mg/kg, i.p.) in the FST. Similarly, L-Arg (750 mg/kg, i.p.), but not D-Arg blocked the anti-immobility effect of L-NNA (3 mg/kg, i.p.) in the FST. The results indicate that either the synthesis of NO or the inhibition of its synthesis may produce antidepressant-like effects when assessed in the FST and TST. The physiological meaning of this finding is still obscure, but it could indicate that NO has a dual role in the modulation of depression.

Animals↗

PubMed2000

Acute treatments with GMP produce antidepressant-like effects in mice.

This study examined the effect of GMP in two models of depression in mice. The immobility times in the forced swimming test (FST) and in the tail suspension test (TST) were significantly reduced by GMP (dose range: 5-50 mg/kg and 5-100 mg/kg, i.p., respectively), without accompanying changes in ambulation in an open-field. I.c.v. injection of GMP (320-480 nmol/site) also reduced the immobility in the FST without affecting ambulation. The immobility of mice treated with MK-801 (0.01 mg/kg) + GMP (50 mg/kg) was not significantly different from the result obtained with MK-801 or GMP alone, but GMP (or MK-801) + imipramine (15 mg/kg) treatment induced a stronger effect in FST than administration of either drug alone. Pretreatment with p-chlorophenylalanine (100 mg/kg, 4 days) completely blocked the anti-immobility effect of GMP, MK-801 or fluoxetine (32 mg/kg), but only partially that of imipramine in the FST. The results suggest that the antidepressant-like effects produced by the administration of GMP, like MK-801, may be due to an indirect serotonin activation resulting from blockade of NMDA receptors.

Animals↗

PubMed2000

Composite surfaces after finishing and polishing techniques.

PURPOSE: To evaluate the effect of finishing and polishing techniques on surface roughness of resin-based composites (RBCs). MATERIALS AND METHODS: Forty specimens of each material were cured under Mylar strips and immersed in artificial saliva for 1 wk. Samples were tested with a profilometer to obtain baseline average surface roughness (Ra). Specimens of both RBCs were then finished and polished according to four techniques: (1) Sof-Lex disks; (2) Sof-Lex disks followed by Prisma Gloss; (3) Enhance points; (4) Enhance points followed by Prisma Gloss application. New readings of the roughness pattern were carried out and the difference of post-polishing and baseline values were analyzed. RESULTS: ANOVA test (alpha = 0.05) did not show differences between materials (P = 0.9393) nor interaction effects (P = 0.3094), but significant difference among the finishing/polishing techniques were detected (P = 0.0157). Tukey's test showed that the smoothest surface was obtained when the specimens were treated by Sof-Lex followed by Prisma Gloss polishing paste; and the worst results were obtained after using Enhance points alone.

Aluminum Oxide↗

PubMed1999

Effects of lead on adenylate cyclase activity in rat cerebral cortex.

Lead decreased in a dose dependent manner the basal AC activity in membranes of rat cerebral cortex (IC50 = 2.5 +/- 0.1 microM). In membranes preincubated under basal conditions, AC activity was stimulated by approximately two and fourfold by 10 microM Gpp(NH)p or forskolin, respectively. Under basal conditions, lead (3 microM) inhibited enzyme activity up to 50%, but was not able to inhibit the Gpp(NH)p- or the forskolin-stimulated AC activity. However, in membranes preincubated with Gpp(NH)p (10 microM), lead (3 microM) had no significant effect on enzyme activity, but it partly blocked the stimulation of AC activity elicited by forskolin (10 microM). In membranes preincubated with 10 microM lead, the addition of 10 microM Gpp(NH)p or forskolin in the incubation medium did not stimulate AC activity. However, when added together in the incubation medium Gpp(NH)p + forskolin produced an increase in enzyme activity. In membranes preincubated with 10 microM lead + 10 microM Gpp(NH)p, Gpp(NH)p (10 microM) or forskolin (10 microM) added alone or in combination to the incubation medium did not stimulate AC activity. Moreover, under these latter conditions lead had no further effect on enzyme activity. These results indicate that lead may interact with G-proteins and with the catalytic subunit of cerebral cortical AC to produce inhibition of the enzyme activity.

Adenylyl Cyclases↗

PubMed1999

Antidepressant-like effect of lead in adult mice.

It has been reported that lead can cause behavioral impairment by inhibiting the N-methyl-D-aspartate (NMDA) receptor complex. MK-801, a noncompetitive NMDA receptor antagonist, exhibits an antidepressant-like action in the forced swimming test. The purpose of the present study was to determine whether subacute lead exposure in adult male Swiss mice weighing 30-35 g causes an antidepressant-like action in a forced swimming test. Mice were injected intraperitoneally (ip) with 10 mg/kg lead acetate or saline daily for 7 consecutive days. Twenty-four hours after the last treatment, the saline and lead-treated mice received an injection of MK-801 (0.01 mg/kg, ip) or saline and were tested in forced swimming and in open-field tests. Immobility time was similarly reduced in the saline-MK-801, Pb-saline and Pb-MK-801 groups compared to the saline-saline group (mean +/- SEM; 197.3 +/- 18.5, 193.5 +/- 15.8, 191.3 +/- 12.3 and 264.0 +/- 14.4 s, respectively; N = 9). These data indicate that lead may exert its effect on the forced swimming test by directly or indirectly inhibiting the NMDA receptor complex. Lead treatment caused no deficit in memory of habituation and did not affect locomotor activity in an open-field (N = 14). However, mice that received MK-801 after lead exhibited a deficit in habituation (22% reduction in rearing responses between session 3 and 1; N = 14) as compared to control (41% reduction in rearing responses; N = 15), further suggesting that lead may have affected the NMDA receptor activity. Forced-swim immobility in a basin in two daily consecutive sessions was also significantly decreased by lead exposure (mean +/- SEM; day 1 = 10.6 +/- 3.2, day 2 = 19.6 +/- 3.6; N = 16) as compared to control (day 1 = 18.4 +/- 3.8, day 2 = 34.0 +/- 3.7; N = 17), whereas the number of crossings was not affected by lead treatment, further indicating a specific antidepressant-like action of lead.

Animals↗