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Biomedical subjects

S R Silva

Publications and source records attributed to S R Silva.

30 records · Page 2Linked to original sources
PubMed1994

Thalidomide for the treatment of uremic pruritus: a crossover randomized double-blind trial.

Our observation that thalidomide administration to a dialysis patient with leprosy alleviated his pruritus led us to conduct this short-term study to assess the efficacy of the drug in this regard. From 210 hemodialysis patients, 29 cases of refractory uremic pruritus were entered into the study. Patients were instructed to score their symptoms from 0 to 3, three times a day and assigned to receive thalidomide or placebo at bed time for 7 days. After a washout period of 7 days, drugs were crossed over. Response was defined as a reduction of at least 50% in the pruritus scoring. Eighteen patients finished the study. In the first phase, 55% of patients responded showing a mean reduction in their pruritus scoring of 78% (p < 0.05 vs. placebo); no response to placebo was observed. A similar proportion of patients responded to thalidomide in the second phase with a mean reduction in their pruritus scoring of 81%. In conclusion, thalidomide can be a precious tool in the handling of uremic pruritus unresponsive to available therapy.

Aged↗
PubMed1994

5-HT2 receptor blockade by ICI 170,809 does not affect the inhibitory effect of the 5-HT1A receptor ligand gepirone on neuroleptic-induced catalepsy.

Considerable experimental evidence suggests that central dopaminergic (DA) transmission is under serotonergic (5-HTergic) modulation. For instance, neuroleptic-induced catalepsy (NIC) in rodents, a behavior mainly due to blockade of DA receptors in the striatum, can be affected by 5-HTergic manipulation. It has been shown that ligands of 5-HT1A receptors (e.g. buspirone, gepirone) reduce NIC, while 5-HT2 receptor antagonists (e.g. ritanserin) do not affect this phenomenon. However, the role of 5-HT2 receptors in the modulation of NIC is still controversial and there is evidence from behavioral models other than NIC suggesting the existence of functional interaction between the two subtypes of 5-HT receptors. The present study was designed to evaluate the effect of ICI 170,809 (a selective 5-HT2 receptor antagonist) on NIC and to test the possible effect of this drug on the anticataleptic effect of gepirone (GP). Male Wistar rats weighing 300-350 g were used, and each animal (7 per group, 4 groups) was used only once. Catalepsy was induced with haloperidol (H; 1 mg/kg, i.p.) and measured at 30-min intervals by means of a bar test. Animals received either ICI 170,809 (3 mg/kg, i.p.) or 0.9% saline (SL; 0.8 ml, i.p.) 30 min before H. At 110 min after H, the rats received GP (1 mg/kg, i.p.) or SL (0.8 ml, i.p.). GP significantly attenuated NIC (e.g. 739 +/- 106 s vs 1009 +/- 85 s for controls, at 150 min after H), while ICI 170,809 did not significantly affect the phenomenon (e.g. 978 +/-89 s vs 1009 +/- 85 s for controls, at 150 min after H). Pretreatment with ICI 170,809 did not significantly modify the anticataleptic effect of GP (e.g. 617 +/- 90 s vs 739 +/- 106 s for SL-pretreated animals, at 150 min after H). These results confirm reports of the anticataleptic effect of GP and the lack of effect of 5-HT2 receptor antagonists on NIC. Moreover, these data also suggest the absence of functional interactions between central 5-HT1A and 5-HT2 receptors in this model of DA transmission.

Animals↗
PubMed1994

Prevalence of caries and dental care status of schoolchildren from urban and rural areas in Araraquara, SP, Brazil.

The research reported was carried out to assess the prevalence of caries and dental care status in schoolchildren from urban and rural areas in Araraquara, SP, Brazil. Schoolchildren from an urban area (1,472) and from a rural area (355), aged 7-12 years were examined by two examiners previously trained using the DMFT index. The results showed that the DMFT index was similar in both areas. At 12 years-of-age, the DMFT was 3.8 in urban schoolchildren and 4.0 in rural schoolchildren, considered moderate according to WHO classification. The dental care status was different in the urban and rural areas. In the urban area, 82.9 per cent of the decayed teeth were filled and in the rural area, only 22.1 per cent. The moderate prevalence of dental caries and the high proportion of filled teeth in the urban area suggest that the implementation of primary prevention programmes is necessary, in both, urban and rural populations.

Brazil↗
PubMed1993

Influence of median raphe nucleus lesions on neuroleptic-induced catalepsy and on the anticataleptic effect of buspirone.

Catalepsy induced by neuroleptics in rats can be modified by 5-hydroxytryptaminergic (5-HTergic) manipulation. For example, buspirone (BUS) and other central 5-HT1A receptor ligands reduce neuroleptic-induced catalepsy (NIC). The dorsal (DRN) and median (MRN) raphe nuclei are reported to be important sources of 5-HTergic projections to the basal ganglia, the site of action of neuroleptics in producing NIC. A previous study showed that lesion of DRN did not affect NIC or the anticataleptic effect of BUS. The present study was designed to evaluate the participation of MRN in NIC and in the anti-NIC effect of BUS. Twenty-four male Wistar rats (N = 6/group) weighing 220-250 g were used. Electrolytic lesion of MRN was carried out in anesthetized rats along with sham operations (electrode inserted but no current applied). Ten days later, the rats were injected with BUS (5 mg/kg, ip) or saline (1 ml, ip). Catalepsy was induced 20 min later with haloperidol (H; 1 mg/kg, ip) and measured at 30-min intervals by means of a bar test. The Costall & Naylor method of scoring (range 0-5 points) was used. Saline-injected MRN-lesioned rats displayed significantly lower catalepsy scores than sham-lesioned rats (1.5 +/- 0.2 vs 3.8 +/- 0.3 at 90 min after H). In sham-lesioned rats, BUS significantly reduced the catalepsy scores in comparison with saline-treated animals (1.3 +/- 0.2 vs 3.8 +/- 0.3 at 90 min after H). However, BUS was not able to further reduce NIC in the MRN-lesioned animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effects of the 5-HT receptor antagonists cyanopindolol, ICI 169,369, cisapride and granisetron on neuroleptic-induced catalepsy in mice.

Typical neuroleptics (e.g. haloperidol) can induce catalepsy in rodents. Selective 5-hydroxytryptamine1A (5-HT1A) receptor antagonists reduce neuroleptic-induced catalepsy (NIC), suggesting that this subtype of serotonin receptor plays a role in the modulation of nigrostriatal dopaminergic transmission. The present study was designed to evaluate the participation of other 5-HT receptor subtypes in NIC. Adult albino mice (both sexes, 26-35 g) were used. Catalepsy was induced with haloperidol (H; 1.5 mg/kg, ip) and measured at 30-min intervals by means of a bar test. Cyanopindolol (a 5-HT1B receptor antagonist), ICI 169,369 (a 5-HT1C/2 receptor antagonist) and granisetron (a 5-HT3 receptor antagonist) were used. Buspirone, a 5-HT1A partial antagonist, cisapride, a 5-HT3/5-HT4 ligand and clomipramine, a 5-HT neuronal uptake blocker, were also employed. These drugs were injected ip, 20 min before H, with each animal (9-10 per group) used only once. Cyanopindolol (0.3 mg/kg) or ICI 169,369 (5 mg/kg) did not significantly affect NIC (375 +/- 39 and 378 +/- 34 s vs 372 +/- 44 s for controls, at 2 h after H). Buspirone (1 mg/kg) reduced, while pretreatments with either granisetron (0.5 mg/kg), cisapride (5 mg/kg) or clomipramine (5 mg/kg) potentiated the cataleptic effect of H (107 +/- 19, 576 +/- 52, 815 +/- 76 and 800 +/- 97 s vs 374 +/- 40 s in the control group, at 2 h after H).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Dorsal raphe nucleus lesions have no effect on neuroleptic-induced catalepsy and on the anticataleptic activity of buspirone.

The anxiolytic drug buspirone (BUS) and other central 5-HT-1A receptor ligands are capable of reducing neuroleptic-induced catalepsy in rodents. The dorsal raphe nucleus (DRN) is reported to be an important source of serotonergic projections to the basal ganglia, the site of neuroleptic action. The present study was designed to evaluate the participation of the DRN in the anticataleptic effect of BUS on male Wistar rats. Rats were submitted to electrolytic or sham DRN lesion under barbiturate anesthesia. Ten days later, the animals were injected with BUS (5 mg/kg, ip) or saline (1 ml, ip) and catalepsy was induced 20 min later with haloperidol (1 mg/kg, ip). Saline-injected DRN-lesioned and sham-lesioned rats displayed similar catalepsy scores and BUS significantly and similarly reduced the catalepsy scores in both groups. The results suggest that, in producing anticataleptic effects, BUS interacts at sites other than the DRN. The participation of other raphe nuclei in the anticataleptic effect of BUS is currently under investigation.

Animals↗
PubMed1990

Inhibition of chlorpromazine-induced catalepsy by the 5-HT-1A ligands pindolol and buspirone in mice.

Neuroleptics such as chlorpromazine and haloperidol are capable of inducing catalepsy in rodents. Non-selective 5-hydroxytryptamine (5-HT) antagonists such as methysergide reduce the cataleptic effect of haloperidol. The present study was designed to evaluate the participation of 5-HT-1A receptors in chlorpromazine-induced catalepsy in mice. Pindolol and buspirone, two putative 5-HT-1A receptor ligands, were used. Pretreatment with these drugs reduced the cataleptic effect of chlorpromazine. Clomipramine, a 5-HT neuronal uptake blocker, reversed the inhibitory effect of buspirone. Pretreatment with clomipramine alone caused a potentiation of neuroleptic-induced catalepsy. These results suggest that central 5-HT-1A receptors play an important role in neuroleptic-induced catalepsy in mice.

Animals↗
PubMed1989

Effects of physostigmine on the activity of medullary raphe neurons in anesthetized rats.

Medullary raphe neurons are involved in the control of sympathetic activity during desynchronized sleep. To determine if cholinergic stimulation of these sites has any effect on raphe unit activity, we administered physostigmine to urethane-anesthetized rats. Most of the neurons (68%) were excited by physostigmine, suggesting the existence of cholinergic synapses which are excitatory for the majority of medullary raphe neurons.

Action Potentials↗
PubMed1982

Mechanism of entry of Toxoplasma gondii into vertebrate cells.

Mouse macrophages and LA-9 cells were infected with Toxoplasma gondii. The percentages of cells containing parasites inside cytoplasmic vacuoles and with parasites attached to the cell surface were determined. Treatment of macrophages or LA-9 cells with either cytochalasin B or 4 degrees C before interaction with T. gondii decreased, but did not totally prevent their infection by the parasite. Observation of the host cell/parasite interaction by scanning electron microscopy revealed images of parasite penetration into cells, even when the cells had been incubated at 4 degrees C or in the presence of cytochalasin B. Two types of cytoplasmic vacuoles, which contained parasites were seen in thin sections of infected macrophages: in one type there was a small space between the membrane of the parasite and the membrane of the vacuole; in the second type the vacuole was very large and contained tubular structures. The results obtained are interpreted as indicative that two mechanisms are used by T. gondii to enter vertebrate cells.

Animals↗
PubMedDate not supplied

Prenatal diagnosis of Down's syndrome in the presence of isolated Ebstein's anomaly.

Ebstein's anomaly is a rare congenital cardiac defect, characterized by the displacement of the tricuspid valve into the right ventricle, that occurs approximately once in 20,000 live births. The association of Ebstein's anomaly and chromosomal abnormalities, such as Down's syndrome, is extremely unusual. Prenatal diagnosis of trisomy 21 in a fetus with isolated Ebstein's anomaly has not been previously reported.

Abortion, Eugenic↗
PubMedDate not supplied

[Arterial hypertension due to mercury intoxication with clinical and laboratorial syndrome simulating pheochromocytoma].

A 17-year-old boy was admitted to hospital because of severe hypertension (200/130 mmHg), headache, irritability, sweating, etc. Initial biochemical tests suggested pheochromocytoma, being treated with nifedipina, clonidina and propranolol. On reporting exposure to mercury vapour, he underwent twenty-four-hour urine screening and measurement of blood mercury which confirmed intoxication. The patient received courses of chelation therapy with dimercaprol (BAL) and penicillamine with remission of symptoms and normalisation of hypertension after 2 months. This case is relevant to current practice regarding similarity between mercury intoxication and hypertension secondary to pheochromocytoma.

English Abstract↗