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Biomedical subjects

C M Alves

Publications and source records attributed to C M Alves.

14 recordsLinked to original sources
PubMed2003

Preliminary study on human protein adsorption and leukocyte adhesion to starch-based biomaterials.

In this study, the adsorption of human serum albumin (HSA), fibronectin (FN) and vitronectin (VN) onto the surface of novel biodegradable materials was evaluated by immunostaining. Specifically, polymeric blends of corn starch with cellulose acetate (SCA), ethylene vinyl alcohol copolymer (SEVA-C), and polycaprolactone (SPCL) were immersed in unitary and competitive systems; that is, binary and more complex protein solutions. For binary solutions, different HSA and FN protein distribution patterns were observed depending on the starch-based surface. Furthermore, the relative amount of proteins adsorbed onto starch-based surfaces was clearly affected by protein type: a preferential adsorption of VN and FN as compared to HSA was observed. On tests carried out with unitary, binary and more complex solutions, it was found that vitronectin adsorption ability was enhanced in competitive systems, which was associated with a lower amount of adsorbed albumin. In order to assess the effect of these human proteins on cell behavior, a mixed population of human lymphocytes and monocytes/macrophages was cultured over pre-coated SEVA-C surfaces. Through anti-CD3 and CD-14 monoclonal antibody labeling and cell counting, leukocyte adhesion onto pre-coated SEVA-C surfaces was analyzed. Based on the results, it was possible to detect albumin long-term effects and fibronectin short-term effects on cell adhesion proving that previously adsorbed proteins modulate leukocyte behavior.

Journal Article↗
PubMed2003

Apoptosis in the cerebellum of dogs with distemper.

Canine distemper virus (CDV) may induce multifocal demyelination in the central nervous system of infected dogs. The pathogenesis of this process is not clear. The present work identifies the presence of apoptotic cells in white and grey matter of dogs'cerebellum, naturally infected with CDV. Fifteen dogs with clinical signs of canine distemper that tested positive for CDV nucleoprotein were used. Brain specimens were processed and embedded in paraffin. Sections 5 microm thick were stained with hematoxylin-eosin and Shorr. Other sections were submitted to TUNEL reaction and to immunohistochemistry for CDV nucleoprotein detection. Acute and chronic demyelinated plaques were observed in the white matter, while apoptosis occurred particularly in the granular layer of grey matter. Apoptosis seems to play an important role in the pathogenesis of canine distemper demyelination.

Animals↗
PubMed2002

Cell adhesion and proliferation on biomimetic calcium-phosphate coatings produced by a sodium silicate gel methodology.

The present study describes a methodology to produce bioactive coatings on the surface of starch based biodegradable polymers or other polymeric biomaterials. As an alternative to the more typical bioactive glass percursors, a sodium silicate gel is being employed as a nucleating agent, for inducing the formation of a calcium-phosphate (Ca-P) layer. The method has the advantage of being able to coat efficiently both compact materials and porous 3D architectures aimed at being used on tissue replacement applications and as bone tissue engineering scaffolds. This treatment is also very effective in reducing the incubation periods, being possible to observe the formation of an apatite-like layer, only after 6 h of immersion in a simulated body fluid (SBF). The influence of the SBF concentration on the formation of the apatite coating was also studied. The apatite coatings formed under different conditions were analyzed and compared in terms of morphology, chemical composition and structure. After the first days of SBF immersion, the apatite-like films exhibit the typical cauliflower like morphology. With increasing immersion times, these films exhibited a partially amorphous nature and the Ca/P ratios became very closer to the value attributed to hydroxyapatite (1.67). The obtained results are very promising for pre-calcifying bone tissue engineering scaffolds. Therefore, in order to study cell behavior and response to these apatite coatings, adhesion, morphology, and proliferation of a human osteoblast cell line (SaOS-2) was also analyzed after being cultured in the coatings formed after 15 days of immersion in SBF. Results indicate a good correlation between crystallinity of the apatite like coatings formed in these conditions and respective cell spreading and morphology. In general, higher cell proliferation was observed for higher crystalline Ca-P coatings.

Journal Article↗
PubMed2001

Percutaneous balloon mitral valvuloplasty in comparison with open mitral valve commissurotomy for mitral stenosis during pregnancy.

OBJECTIVES: We sought to compare the maternal and fetal outcomes of patients with severe mitral stenosis submitted to percutaneous balloon dilation versus open mitral valve commissurotomy (MVC) during pregnancy. BACKGROUND: Heart failure in patients with mitral stenosis complicating pregnancy is a common problem in developing countries. Since 1984, percutaneous dilation of the mitral valve using a balloon catheter has become a therapeutic alternative to open heart surgery. Although the efficacy of percutaneous mitral valve balloon dilation is well established, its results have never before been compared with the results of commissurotomy during pregnancy. METHODS: We compared the clinical and obstetric complications in 45 women who were treated with percutaneous mitral valve balloon dilation (group I, n = 21; from 1990 to 1995) or open MVC (group II, n = 24; from 1985 to 1990) for severe heart failure due to mitral stenosis during pregnancy. RESULTS: In our study, percutaneous balloon dilation of the mitral valve had a success rate of 95% (Gorlin formula) and 90.5% (echocardiographic "pressure half-time" method), as demonstrated by the final mitral valve area achieved. This improvement was followed by a marked decrease in the mitral valve gradient, left atrial pressure and mean pulmonary artery pressure. Patients in both groups had similar improvements in symptoms. Patients who underwent percutaneous balloon dilation had significantly fewer fetal complications, with a reduction in fetal and neonatal mortality (1 death in group I vs. 8 in group II, p = 0.025). CONCLUSIONS: Percutaneous balloon mitral valvuloplasty is safe and effective and appears to be preferable for the fetus, compared with open MVC during pregnancy.

Adult↗
PubMed2000

Effect of low-dose prednisone in vivo on the ability of complement receptor to mediate an oxidative burst in rat neutrophils.

Glucocorticoids have been used in the treatment of a variety of inflammatory processes including autoimmune diseases. However, the influence of low-dose glucocorticoids on the respiratory burst activity of neutrophils has not been studied. The aim of this work was to study the effect of treatment with low-dose prednisone on the oxidative burst of rat peripheral blood neutrophils. Wistar male rats were treated with prednisone by gavage (28, 87 or 257 microg/animal/day) for 7 or 15 days. These doses are equivalent to 10, 30 or 90 mg/adult human ( approximately 70 kg)/day, respectively. Sera from normal rats were used to opsonize zymosan (opZy). Neutrophils (1x10(5)) were stimulated by opZy and the oxidative burst of control or treated rat cells was measured by luminol-dependent chemiluminescence (CL). Prednisone did not affect the CL of rat neutrophils for either period of treatment, or any studied doses, when compared with controls. These results suggest that the low-dose prednisone has no effect on the oxidative burst mediated by complement receptors during the rat neutrophil phagocytosis of complement-opZy.

Animals↗
PubMed1998

[Stenting for iatrogenic coronary dissection treatment].

Catheter-induced coronary dissection is rare but has a significant mortality and morbidity. The ideal management of acute coronary occlusion, whatever the cause, is the prompt restoration of the vessel patency to limit the extent and duration of ischemia. In the setting of dissection during angiography the usual approach to myocardial salvage has been emergency aortocoronary bypass surgery preceded by insertion of an intra-aortic balloon. The main disadvantages of this approach is the delay in performing emergency surgery, mainly in centers without surgical back-up on site. The authors present a case of an elderly woman with left circumflex artery dissection caused by the catheter during coronary angiography. This problem was successfully managed using an intracoronary stent. This technique has potential advantages in terms of the speed of reperfusion and availability in centers performing diagnostic angiography without surgical back-up on site.

Aged↗
PubMed1998

[Utilization of self-expandable prosthesis (stent) introduced through the femoral artery for treatment of dissection of the descending aorta].

PURPOSE: We present four cases of dissection of the thoracic descending aorta that underwent treatment with an auto expandable dácron-covered stent. METHODS: The stent was deployed through the femoral artery in the hemodynamic laboratory after sedation, local anesthesia in both inguinal areas and systemic heparinization. The catheter with the stent was introduced through a cutdown in the left femoral artery until the area in the thoracic aorta with the previously diagnosed tear. RESULTS: The stent was expanded with immediate occlusion of the false lumen. The whole procedure took 90 minutes and the patients were discharged without complications. CONCLUSION: Stent utilization is an important step to improve treatment results in type B aortic dissection.

Acute Disease↗
PubMed1996

Human immune response to epitopes on the meningococcal outer membrane class 5 protein following natural infection.

Two monoclonal antibodies (mAbs) were produced against a serogroup B Neisseria meningitidis strain. These mAbs recognized two epitopes in the class 5 outer membrane proteins (OMP), designated P5.7 and P5.Bm, and were able to kill the homologous strain through complement activation. Both epitopes were surface exposed and 68% of group B meningococcal clinical isolates had one or both epitopes present in their class 5 OMP. Antibodies to one or both epitopes were demonstrated in 17 patients with meningococcal meningitis using an ELISA inhibition assay. Of the 17 paired sera, 41% and 29% of the acute-phase sera had antibodies to the P5.7 and P5.Bm epitopes, respectively. Immunoglobulin G to P5.Bm were found in all 17 convalescent-phase sera while specific antibodies against P5.7 were only found in 6 of these sera. These results demonstrate the potential importance of the P5.Bm and P5.7 epitopes on the class 5 OMP as candidates for vaccine composition.

Antibodies, Bacterial↗
PubMed1995

Decrease in the ratio of high- to low-affinity isozymes of (Na+ +K+)-ATPase during the development of rat cardiac ventricles.

The ratio of (Na+ +K+)-ATPase (EC 3.6.1.3.)isoforms with high and low affinity for cardiac glycosides was studied in heart preparations from neonatal, 3-month and 6-month old Wistar rats. Biphasic ouabain inhibition curves of (Na+ +K+)-ATPase activity indicated that the relative contribution of the high-affinity process decreased from 34% at 9 days to 23% at 3 months and to 10% at 6 months. Scatchard plots for [3H]ouabain binding were curvilinear and indicated that the relative contribution of the high-affinity sites (Kd = 0.1-0.25 microM) decreased by about one-half between 3 months (19-24%, N = 2) and 6 months (9-11%, N = 2).

Age Factors↗
PubMed1993

Pyrexia in hospitalised spinal cord injury patients.

To discover the frequency of pyrexia in spinal cord injury (SCI) patients in the Hospital for Medicine of the Locomotor System (HMLS/SARAH), a review study was undertaken. For a period of 3 months, all new episodes of fever were recorded. During the study 221.3 patients/month were observed. The age ranged from 14 to 60 years and time of lesion from 1 to 6,264 days: 85 patients were paraplegia or paraparetic, and 44 tetraplegic or tetraparetic. At the beginning of the study 10.8% of the patients had fever. During follow up, we observed a rate of 33.9 new incidences per 100 patients/month. In 77.3% only one cause was identified, and in 8% no cause could be defined. The commonest causes were urinary tract infection (UTI) (44.3%), and soft tissue infections (11.4%). Frequent causes of fever in the acute stage other than UTI were complications related to the initial trauma and thromboembolic disease (p < 0.05). These results demonstrate the high incidence of fever in patients with SCI, in addition to providing a useful approach for diagnosis and management.

Adolescent↗
PubMed1993

[Hemodynamic study with Swan-Ganz catheterization, concomitant to endomyocardial biopsy in heart transplantation patients. Importance in the early diagnosis of rejection].

PURPOSE: To evaluate the role of hemodynamic parameters in the diagnosis of acute rejection who underwent orthotopic cardiac transplantation. METHODS: A protocol was carried out in 19 patients who underwent heart transplantation and in whom Swan-Ganz hemodynamics was performed immediately prior to routine endomyocardial biopsy in the first few months postoperatively. The results of 28 biopsies were divided in group I--severe rejection who needed pulse-therapy (n = 10) and group II--No or mild/moderate rejection who did not need any pulse (n = 18). Hemodynamic parameters were compared between both groups. RESULTS: There were significant differences among hemodynamic parameters in groups I and II. Group I had higher mean right atrial pressures (13.0 x 7.3 mmHg), mean pulmonary pressure (26.3 x 20.4 mmHg), mean wedge pressure (14.4 x 10.9 mmHg) and lower cardiac index (2.57 x 3.10 l/min/m2). CONCLUSION: In a routine situation, hemodynamic measurements, as obtained with Swan-Ganz catheter, simultaneously with endomyocardial biopsies, show significant alterations in transplanted patients who develop acute rejection. This information, obtained earlier than the biopsy results, could shorten the time to initiate pulse-therapy in patients with severe rejection.

Adult↗
PubMed1993

[Percutaneous retrieval of intravascular foreign bodies].

PURPOSE: To report our experience on percutaneous vascular foreign body retrieval and to analyse current techniques employed. METHODS: From 1985 to 1991, 15 (0.18%) of 7,963 procedures performed in the Cardiac Catheterization Laboratory-Hospital São Paulo were intravascular foreign body retrieval: 9 (60%) intracath, 4 (26.8%) diagnostic catheters, one Swan Ganz catheter entrapped at superior cava vein and one fragment of angioplasty guide-wire in the circumflex branch of the left coronary artery. The snare technique was used in 11 cases, a endomyocardial bioptome device in 1 case and modified snare technique for the intracoronary wire fragment retrieval was used in 1 case. In two cases of embolized fragment in peripheral arteries, no attempt was done for retrieval. RESULTS: All (100%) of the 13 attempted procedures were successful. The two foreign bodies not removed had an uneventful follow-up. CONCLUSION: The snare technique for percutaneous retrieval of intravascular foreign bodies is safe and has excellent results. The management peripheral fragments is not well defined yet.

Adult↗
PubMed1992

Traumatic injury to the spinal cord. Prevalence in Brazilian hospitals.

Traumatic spinal cord lesions have a worldwide high morbidity and mortality, and in many developed countries the problem has received special attention, based on epidemiological studies. In Brazil these studies have been restricted to institutional data. In 1988 a survey conducted by the Integrated System of Traumatology and Orthopaedics, covering 36 public hospitals from 7 Brazilian capitals, revealed a point prevalence of 8.6% (108 patients) with spinal cord injury, aged from 6-56 years; 81% were men. The most frequent causes were traffic accidents (42%), firearms (27%) and falling from heights (15%). The main complications were pressure ulcers (54%) and urinary infections (32%).

Adolescent↗