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Biomedical subjects

L S Pereira

Publications and source records attributed to L S Pereira.

13 recordsLinked to original sources
PubMed2001

Production of reactive oxygen species by hemocytes from the cattle tick Boophilus microplus.

We have investigated the phagocytic activity and the production of reactive oxygen species (ROS) by hemocytes from the cattle tick Boophilus microplus. Two main types of hemocytes were detected in tick hemolymph: plasmatocytes and granulocytes. The plasmocytes were the most abundant cells, being responsible for the in vivo phagocytosis of yeast. ROS production was evaluated by luminol-amplified luminescence and phenol red oxidation. The luminescence increased when hemocytes were incubated with bacteria, zymosan, or phorbol 12-miristate 13-acetate (PMA). The luminescence was inhibited by superoxide dismutase and catalase, which are antioxidant enzymes that remove superoxide and hydrogen peroxide, respectively. The phenol red oxidation assay also showed an increase in the level of hydrogen peroxide produced by hemocytes stimulated with bacteria and PMA. Taken all together, our data indicate that tick hemocytes are able to produce ROS during the phagocytic process similarly to vertebrate phagocytes.

Animals↗
PubMed2001

Hyperalgesia and edema responses induced by rat peripheral blood mononuclear cells incubated with carrageenin.

The aim of this study was to verify the role played by mononuclear cells in an acute (nonimmune) inflammatory reaction. Mononuclear cells purified from rat peripheral blood were incubated for 1, 2, or 24 h with 100 or 250 microg/ml carrageenin (Cg). The resultant donor supernatant was injected into recipient rats to test its ability to induce hyperalgesia (reduction in threshold for paw pressure) and edema (increase in paw volume). Mononuclear cell supernatants (MnS) induced a significant time- and dose-dependent hyperalgesia and edema in rat paws, which reached a maximal effect at 3 h, lasted for 6 h, and returned to basal levels at 24 h of injection. Prostaglandins and cytokines (interleukin 1, 2, 6, 8, and tumor necrosis factor alpha) accounted for the hyperalgesia induced by MnS, as it was reduced (40 to 90%) by synthesis inhibitors such as indomethacin, dexamethasone, rolipram, and cyclosporin added to the cultures at a microgram dose-range. Edema was dependent on serotonin release in rat paws. These results indicate that mononuclear cells may be important contributors to acute inflammatory reactions, especially under those conditions where pain is an important component.

Animals↗
PubMed1998

[Cornual pregnancy].

Cornual ectopic pregnancy is a rare entity, found in 2-4% of all ectopic pregnancies, with an estimates incidence of one in every 2500 to 5000 deliveries. It represents a high rate of maternal mortality because of the growth and secondary rupture of the zone of implantation in advanced gestational ages, resulting in severe hemodynamic decompensation. We realizes a retrospective study from January 1989 to December 1994 at Instituto Nacional de Perinatologia. Only 6 cases of ectopic cornual pregnancies were found out of 35,080 deliveries reported, and of 149 ectopic pregnancies in general. Maternal age, gestational age at time of diagnosis, signs and symptoms, surgical treatment complications, and histopathologic report were some of the data collected. Maternal age in average was found to be 31.5, gestational age at time of diagnosis between 7.1 to 24 weeks. All patients referred diffuse abdominal pain and amenorrhea, with 2 cases of transvaginal bleeding. The 100% of cases required total abdominal hysterectomy as surgical treatment, and the most important complication found was shock, hence no maternal deaths were reported. We found this pathology to have an incidence of 1 of 5846 deliveries at our Institution, representing the 0.01% Of all ectopic pregnancies, we found to have an incidence of 4.02% that agrees with world literature.

Adult↗
PubMed1997

Cyclosporin inhibits hyperalgesia and edema in arthritic rats: role of the central nervous system.

Since arthritis induced by Mycobacterium products (adjuvant) in rats is considered to be immunologically driven, the objective of the present study was to determine if the immunosuppressor drug cyclosporin could affect hindpaw edema and joint hyperalgesia simultaneously. Female Holtzman rats (140-170 g) presented hyperalgesia and edema on the 8th and 12th day following adjuvant injection. Daily systemic (oral or intramuscular) administration of cyclosporin (0.5-5.0 mg kg (-1) day (-1)) or dexamethasone (0.01-0.1 mg kg (-1) day (-1)) for 15 days starting on day zero dose-dependently inhibited the hindpaw edema and hyperalgesia in arthritic rats. However, hyperalgesia but not edema could be detected two days after cyclosporin withdrawal. We concluded that a) the continuous presence of cyclosporin is essential to reduce the development of joint hyperalgesia and that b) different mechanisms underlie the appearance of hyperalgesia and edema in this model. The intracerebroventricular (i.c.v.) administration of 5-50-fold smaller doses of cyclosporin (1.5-150 micrograms/day) or dexamethasone (15 micrograms/day) also reduced the arthritic hindpaw edema and hyperalgesia. Peripheral blood from animals injected with effective systemic cyclosporin doses showed detectable levels of the drug, whereas peripheral blood from those injected with i.c.v. cyclosporin did not, as measured by specific RIA. Our results indicate that cyclosporin administered by the central route is as effective as by the systemic route to reduce joint hyperalgesia and hindpaw edema in arthritic rats. The antiarthritic effect induced by low doses of cyclosporin in the central nervous system (CNS) could be explored to avoid it often associated systemic side effects during chronic therapy. However, the mechanism(s) involved in the antiarthritic response to cyclosporin in the CNS remain to be elucidated.

Animals↗
PubMed1997

[The echocardiographic diagnosis of a rare complication of an aneurysm of the sinus of Valsalva].

We report the case of a patient with complete heart block caused by extension of a congenital aneurysm of the sinus of Valsalva into the upper interventricular septum, which was diagnosed by transthoracic and transesophageal echocardiography. We emphasize the rarity of this pathology and the value of transesophageal echocardiography in its assessment, providing a complete anatomicofunctional characterization and allowing surgical repair without previous cardiac catheterization.

Adult↗
PubMed1996

Analysis of exon and intron mutants in the cytochrome b mitochondrial gene of Saccharomyces cerevisiae.

The nucleotide changes present in a group of five cytochrome b mit- mutants were analyzed at the sequence level. Two single-base changes were found: one (M10-152) generated a nonsense codon in the first exon while the other (M8-181) created a missense substitution in the second exon. The other mutants all have multiple (three) substitutions that either resulted in a missense mutation in a coding region (M17-162) or else changed nucleotides in the last intron of the gene, so blocking its excision (M6-200 and M8-53). The synthesis of mitochondrial polypeptides and the steady state concentration of the complex-III subunits were examined. The Rieske protein and the core-4 and core-5 subunits were much reduced in all mutants. Consequently the overall stability of complex III is very sensitive even to amino-acid substitutions in the cytochrome b protein. Mutant M8-53 provides direct evidence for the proposed role of the P9.1 stem in the core structure of the group-I type last intron of this gene.

Apoproteins↗
PubMed1992

[Value of transesophageal echocardiography in the diagnosis of acute aortic dissection].

We describe our experience of six patients with clinical suspicion of acute aortic dissection (AAD) who were studied consecutively by transesophageal echocardiography (TEE) from April to July of 1991. All of them were previously submitted to transthoracic echocardiogram. The diagnosis was correctly established by TEE in five cases, confirmed by aortography and/or surgery (four cases), or by autopsy (one case). In one patient the diagnosis of AAD was excluded by TEE, and posteriorly by nuclear magnetic resonance. Four patients had a Stanford type A, and one patient a type B dissection. The site of entry was identified in three cases; the intimal entry tear of the type B dissection, not observed by TEE, was localized in the aortic arch by aortography. In three of the four type A dissection cases, a thrombus in the false lumen and an aortic regurgitation were found. No other noninvasive methods were used after the diagnosis of AAD by TEE. The surgical repair was successful in three cases, one of which, without previous necessity of aortography. In our experience, TEE increased extraordinarily the diagnosis efficacy of AAD, making possible an earlier therapeutic approach, and probably contributing to the improvement of the prognosis of this pathology.

Acute Disease↗
PubMed1990

[Ruptured aneurysm of the sinus of Valsalva into the right ventricle--apropos of a case].

A 37 year old man was referred to our institution because of a cardiac murmur, exertional dyspnea and fatigue, symptoms that began since 18 years of age. He reported a cardiac murmur since childhood, with no past history of rheumatic fever or infectious endocarditis. On clinic examination there was a systolic-diastolic murmur louder in the third and fourth left intercostal space, just at the sternal left border. The 2 D-echo revealed a small disruption in the aorto-septal continuity. Right heart catheterisation was performed, showing an increased pressure in the pulmonary artery and right ventricle; an increase in the oxygen saturation on the right heart chambers, suggested the presence of a left-to-right shunt, nevertheless the exact location of the defect was not possible to recognise. The study was complemented with Doppler color flow imaging that revealed a turbulent flow through the defect, with blood flowing from the aortic root into the right ventricular outflow tract. The diagnosis of ruptured aneurysm of sinus of Valsalva was made, being confirmed later by aortic angiography. A rare case is reported in which an aneurysm of the right coronary sinus ruptured into the right ventricle; we emphasize the important contribution of the Doppler color flow imaging to the correct diagnosis, technique rarely described in this type of complication.

Adult↗
PubMedDate not supplied

[Value of ventricular geometry in the evaluation of direct ventricular pressure].

OBJECTIVE: To determine the echocardiographic end-systolic ventricular geometry value in evaluating right ventricular systolic pressure (RVSP). MATERIAL AND METHODS: We studied prospectively 68 patients (mean age = 6.0 +/- 5.0 years), submitted to cardiac catheterization for cardiac disorders not involving left ventricular (LV) outflow tract obstruction, within 24 hours after two-dimensional echocardiographic (2D echo) examination. 2D echo evaluation of RVSP was performed using end-systolic LV transverse orthogonal diameters (TDR). The LV transverse orthogonal diameters (antero-posterior and supero-inferior) were measured on a parasternal short-axis image, at the tips of papillary muscles. 2D echo semi-quantitative evaluation of RVSP was tested correlating TDR with hemodynamic RVSP/LV systolic pressure (LVSP) ratio--group 1. We also used regression equation derived from the first 35 patients to quantify RVSP in the last 33 patients--group 2. In these cases, systolic systemic arterial pressure measured by sphygmomanometry was taken as LVSP. RESULTS: The TDR ranged from 1.0 to 2.1 (mean = 1.5 +/- 0.3) and the RVSP/LVSP ratio from 0.3 to 1.7 (mean = 0.7 +/- 0.4). All patients with RVSP/LVSP greater than or equal to 65% have TDR greater than or equal to 1.3 and when RVSP less than or equal to 35 mmHg we always obtained TDR less than or equal to 1.2. The correlation between 2D echo estimated and catheter measured RVSP shows, for group 1, r = 0.88 and y = 1.1X-0.88 and, for group 2'. r = 0.88. CONCLUSION: In the absence of LV systolic obstruction, TDR is a reliable non invasive method in evaluating the RVSP.

Adolescent↗