Biomedical subjects

M Almeida

Publications and source records attributed to M Almeida.

At least 37 records · Page 2Linked to original sources

PubMed2000

[The angioplasty of chronic coronary occlusions with the excimer laser for debulking followed by stent implantation].

UNLABELLED: Coronary angioplasty (PCI) of chronic total occlusions (CTO), even when successful, are associated to less favourable long term results. The recent use of coronary stents has improved the long term outcome of those interventions. PURPOSE: To evaluate the short term results and long term occurrence of major adverse coronary events (MACE): death, MI, urgent revascularization and the need for a new target vessel revascularization (TVR) in patients with CTO who had previously been submitted to a PCI with excimer laser for plaque debulking followed by a provisional stent. POPULATION: From our database, we selected 19 patients with a mean age of 51 +/- 13 years (18 male) submitted to PCI between 1994 and 1998. Of those patients, 10 had had of a previous MI. Hypertension, smoking habits and hypercholesterolemia were present in 9 patients (42%). Two patients had diabetes. The main reason for PCI was stable angina in 16 patients (84%) and unstable in 3 patients (16%). Single-vessel disease was present in 18 patients (94%) and multiple-vessel in 1 patient (6%); left ventricular ejection fraction was preserved in 18 patients (94%). Single vessel PCI was performed in 16 patients (84%) and double vessel in 3 patients. Plaque debulking with excimer laser was performed in all patients, followed by 23 stents (Multilink--8; Gianturco Roubin--5; Palmaz Schatz--4; others--6). The mean clinical follow-up was 19 months. RESULTS: There were no major short-term clinical events (death, MI or urgent revascularization). During follow-up, TVR was only required in 5 patients (26%), all of them in the first 7 months after PCI. CONCLUSIONS: In the highly selected population, PCI for chronic total occlusion, with excimer laser plaque debulking followed by provisional stents, was a safe procedure with a very acceptable rate of new target vessel revascularization in the follow-up period.

Adult↗

PubMed2000

Prognostic value of cardiac troponin I release kinetics in unstable angina.

BACKGROUND: Cardiac Troponins (cTn) are useful in unstable angina (UA). Moreover the different elevation patterns that can be observed in this condition seem to have different prognostic implications. AIM: To study cTn kinetics and cTn nadir in patients with UA, defined as angina at rest within the last 24 hours before admission accompanied by ischemic ECG changes and no myocardial infarction (MI) enzymatic criteria. POPULATION AND METHODS: Samples were collected from 156 patients for cardiac enzymes and cTnI at admission and at 6, 12, 18 and 24 hours. The chemilluminescence method (Access/Sanofi Pasteur) was used for cTnI. The primary end-point at 30 days was the combined occurrence of death, MI and recurrent ischemia. RESULTS: All determinations were below 0.10 ng/ml (group N) in 114 patients and the other 42 pts (group P) had at least one value equal to or above 0.10 ng/ml. The primary endpoint was observed in 24.6% of group N pts compared with 45.2% of group P pts (p = 0.02). Three different patterns of cTnI kinetics were observed. This enabled the identification of a subgroup--group N pts with increasing cTnI values within the first 12 hours and a total differential value > or = 0.03 ng/ml--with an increased risk (50.0% versus 21.4%--p = 0.02--Kaplan-Meier test). CONCLUSION: Besides the prognostic value conferred by cTnI elevation, cTnI kinetics analysis established another sub-group of patients with an adverse prognosis at 30 days follow-up, despite having a negative cTnI.

Adult↗

PubMed1999

Unusual self-association properties of transthyretin Y114C related to familial amyloidotic polyneuropathy: effects on detection and quantification.

We performed biochemical and immunological examinations of heterozygotic carriers of the transthyretin (TTR) mutant Y114C associated with familial amyloidotic polyneuropathy (FAP). The total serum TTR levels in Y114C TTR carriers were extremely low when analyzed by single radial immunodiffusion (SRID), whereas by indirect enzyme-linked immunosorbent assay (ELISA) procedure, their total TTR concentrations were increased. Recombinant homozygotic Y114C TTR showed no immunoreactivity towards a TTR antibody when analyzed by SRID, whereas by the ELISA procedure presented the same degree of reactivity as that of normal TTR or isolated serum heterozygotic Y114C TTR. These results indicate that immunodifusion based techniques cannot properly determine TTR serum levels in Y114C carriers. Analyses of serum TTR of the Y114C TTR carriers by electrospray ionization mass spectrometry (ESI-MS) with the orifice corn voltage at 60 V revealed a small peak of the free Y114C TTR in addition to large TTR peaks of normal TTR. The levels of the free mutant TTR increased with the orifice corn voltage at 90 V. In contrast, increase in orifice voltage from 60 to 90 V produced a reduction in the level of normal TTR. The results suggest a different pattern of association between monomers in Y114C relative to normal TTR.

Adult↗

PubMed1999

Porosity control of hydroxyapatite implants.

Conformation of hydroxyapatite (HAp) bodies was carried out using a multiple slip-casting technique, in order to obtain dual-layer samples with differential sized porosities. The external layer, because of its porosity, controlled by the addition of organic compounds (polyvinyl polyacrylate, PVC), will promote bone ingrowth. The internal denser layer, due to the addition of lithium phosphate (Li3PO4) as sintering additive, will give mechanical resistance to the implant. HAp aqueous suspensions were characterized by rheological measurements. Scanning electron microscopy (SEM) and intrusion mercury porosimetry (MP) were used to characterize sintered bodies. It can be concluded that it is possible to introduce gross porosity in HAp bodies by the addition of organic compounds. The results show that a compatible shrinking of the layers during the sintering process and a good frequency of pores with an appropriate size in the external layer can be achieved with the use of organic additives.

Journal Article↗

PubMed1999

[Elective coronary angioplasty in acute coronary syndromes: early versus delayed treatment].

BACKGROUND: In patients with acute coronary syndromes (ACS) the optimal time required to stabilize the patient before attempting coronary intervention (PTCA) is uncertain. The recent use of newer devices and antiplatelet drugs allowed earlier percutaneous intervention. OBJECTIVE: We examined the efficacy and safety of coronary angioplasty in patients with ACS according to the period of stabilization with medical therapy. METHODS: We included 83 patients, 15 female, 54 with unstable angina and 29 with non-ST elevation myocardial infarction. We studied the rate of complications related to the procedure, the duration of CCU and hospital stay according to the period of stabilization with medical therapy: < 48 hours (early PTCA) and > or = 48 hours (delayed PTCA). RESULTS: No significant differences were found between the two groups of patients with respect to success rate (92% in early PTCA vs 98% in delayed PTCA), stents implantation (74% vs 78%), use of abeiximab (42% vs 24%), abrupt closure during procedure (3% vs 2%), infarct related procedure (0% vs 7%), re-PTCA (5% vs 7%) and surgical revascularization (0% vs 2%). No deaths occurred, CCU stay (2.5 vs 6.7 days, p < 0.001) and hospital stay (4 vs 9.4 days, p = 0.001) were significantly shorter in the group of early PTCA. CONCLUSIONS: In the present group of patients with ACS, early coronary intervention was a safe procedure with a shorter CCU and hospital stay compared with deferred PTCA.

Abciximab↗

PubMed1999

[Peripheral revascularization by cardiologists].

OBJECTIVE: To analyse the initial experience in peripheral arterial revascularization, using percutaneous techniques, by interventional cardiologists. DESIGN: Retrospective clinical study. SETTING: Cardiology department of a specialised public non-university hospital. PATIENTS: Twenty patients, 18 male and 2 female, with ages between 37 and 84 years, who underwent peripheral interventions between May 5 1989 and February 20 1998. INTERVENTIONS: Patients were subdivided into two groups: Group I, 9 patients, 8 male, average age of 56 +/- 13 years, undergoing renal artery angioplasty; Group II, 11 patients, 10 male, average age of 63 +/- 10 years, undergoing angioplasty of the distal aorta (1), of the right subclavian artery (1), of the iliac arteries (6) and of the femoral arteries (3). In Group I, 11 arteries were dilated, 6 by balloon angioplasty and 5 with stent implantation (Palmaz-Schatz--4 and Symphony--1). In Group II, 12 arteries were dilated, 5 by balloon angioplasty and 7 with 12 stent implantations (Palmaz-Schatz--6, Symphony--5 and NIRTM--1). In 8 patients, 1 of Group I and 7 of Group II, coronary angioplasty was also performed in 14 arteries and 18 segments, exclusively by balloon (3 patients) or with 10 stent implantations (5 patients). RESULTS: There was angiographic success in all patients (100%) and clinical success in 85% (17/20) of patients. All clinical complications occurred in Group I patients: retroperitoneal bleeding in one; right femoral artery pseudoaneurysm requiring surgery in one patient: acute renal failure in one patient. There were no cardiac complications in patients undergoing peripheral and cardiac angioplasties at the same stage. In the mean follow-up period of 26 months, one patient required reangioplasty of a right iliac artery and another underwent iliac-femoral bypass, both of Group II and before peripheral stents were available. CONCLUSIONS: Percutaneous peripheral arterial revascularization performed by experienced interventional cardiologists seems safe and efficient, being perfectly justified in patients requiring simultaneous coronary angioplasty.

Adult↗

PubMed1998

NF-kappaB mediates alphavbeta3 integrin-induced endothelial cell survival.

The alphavbeta3 integrin plays a fundamental role during the angiogenesis process by inhibiting endothelial cell apoptosis. However, the mechanism of inhibition is unknown. In this report, we show that integrin-mediated cell survival involves regulation of nuclear factor-kappa B (NF-kappaB) activity. Different extracellular matrix molecules were able to protect rat aorta- derived endothelial cells from apoptosis induced by serum withdrawal. Osteopontin and beta3 integrin ligation rapidly increased NF-kappaB activity as measured by gel shift and reporter activity. The p65 and p50 subunits were present in the shifted complex. In contrast, collagen type I (a beta1-integrin ligand) did not induce NF-kappaB activity. The alphavbeta3 integrin was most important for osteopontin-mediated NF-kappaB induction and survival, since adding a neutralizing anti-beta3 integrin antibody blocked NF-kappaB activity and induced endothelial cell death when cells were plated on osteopontin. NF-kappaB was required for osteopontin- and vitronectin-induced survival since inhibition of NF-kappaB activity with nonphosphorylatable IkappaB completely blocked the protective effect of osteopontin and vitronectin. In contrast, NF-kappaB was not required for fibronectin, laminin, and collagen type I-induced survival. Activation of NF-kappaB by osteopontin depended on the small GTP-binding protein Ras and the tyrosine kinase Src, since NF-kappaB reporter activity was inhibited by Ras and Src dominant-negative mutants. In contrast, inhibition of MEK and PI3-kinase did not affect osteopontin-induced NF-kappaB activation. These studies identify NF-kappaB as an important signaling molecule in alphavbeta3 integrin-mediated endothelial cell survival.

Animals↗

PubMed1998

Orientation of the heme vinyl groups in the hydrogen sulfide-binding hemoglobin I from Lucina pectinata.

Hemoglobin I (HbI) from the claim Lucina pectinata is a unique heme protein that binds and transfers hydrogen sulfide (H2S) to a symbiotic bacteria. The metcyano, metaquo, carbon monoxy, oxy, and deoxy complexes of HbI were studies by resonance Raman (RR) spectroscopy, and the metacyano and carbon monoxy complexes were also studied by 1H-NMR. The results indicate a unique orientation of the heme 2-vinyl group relative to other heme proteins. The RR spectra of the HbICO, metHbICN, metHbIH2O, HbIO2 and deoxyHbI heme derivatives show a band at 1621 cm-1 and a shoulder at 1626 cm-1, indicative of an out-of-plane position for one of the vinyls relative to the other one. Spin-lattice relaxation properties of protons in the metHbICN complex also suggest a unique orientation for the heme 2-vinyl group of HbI. The longitudinal relaxation time (T1) for the 2-H alpha, 2-H beta c, and H beta t protons are 120 ms, 115 ms, and 135 ms, respectively. The data from both techniques suggest an out-of-plane and trans-oriented 2-vinyl group, and an in-plane and cis-oriented 4-vinyl group for the low-spin complexes of HbI. These results imply that the electron withdrawing character of the out-of-plane vinyl group contributes to the stability of the heme Fe+3 oxidation state, facilitates the binding of the H2S ligand, and promotes the stability of this ferric H2S complex.

Animals↗

PubMed1998

Evidence for a role of osteopontin in macrophage infiltration in response to pathological stimuli in vivo.

Previous studies have suggested that osteopontin, an arginine-glycine-aspartate-containing secreted protein, might be important in macrophage accumulation during interstitial nephritis and wound healing. The current study investigated the role of osteopontin in intradermal macrophage infiltration using immunohistochemistry and neutralizing antibodies. Purified osteopontin induced macrophage accumulation after injection in rat dermis and facilitated adhesion and migration of cultured macrophage-like cells in vitro. Intradermal injection of N-formyl-met-leu-phe (FMLP), a potent macrophage chemotactic peptide, induced a macrophage-rich infiltrate at the site of injection. Most of these macrophages expressed high levels of osteopontin as shown by immunochemical analysis. To determine whether osteopontin expressed by macrophages was required for their infiltration, we treated rats with either anti-osteopontin neutralizing antibody (OP199) or nonimmune antibody. We found that FMLP-induced macrophage accumulation was largely inhibited (>60%) by anti-osteopontin antibody treatment compared with rats receiving nonimmune antibody. These data support the hypothesis that osteopontin may be a critical mediator of inflammation in specific disease and injury states, potentially by promoting macrophage adhesion and migration.

Animals↗

PubMed1998

[Revascularization in patients with prior coronary bypass surgery].

UNLABELLED: Increasingly over the past several years, patients have returned after coronary surgery for reintervention procedures. This reflects immediate postsurgical complications and the relentless progression of coronary artery disease in the native circulation and in the bypass grafts. Although there are randomized comparative data for coronary bypass surgery (CABG) versus percutaneous transluminal coronary angioplasty (PTCA) and medical therapy, these trials have always excluded patients with previous (GABG). OBJECTIVES: We attempted to compare the risks and benefits of percutaneous transluminal coronary angioplasty (PTCA) and repeat coronary artery bypass grafting (re-CABG) in patients with previous coronary bypass surgery (CABG). METHODS AND RESULTS: This study examines follow up data (15.4 +/- 11.0 months) from 130 patients with previous CABG, who required either PTCA (Group A, n = 73) or re-CABG (Group B; n = 57) at a single center from 1994 to 1997. Follow up data were obtained from subsequent office visits and telephone calls. The PTCA and re-CABG groups were similar with respect to gender (86% vs 94% males), mean age (62 +/- 9 vs 59 +/- 10 years), angina CCS classes 3 and 4 (73% vs 69%), diminished left ventricular function (23% vs 26%), risk factors such as diabetes (19% vs 17%), hypercolesterolemia (49% vs 45%) and smoking (48% vs 39%) and three-vessel native coronary artery disease (67% vs 72%). The symptomatic status prior to the revascularization procedure was similar in both groups. Complete and functional revascularization was achieved in 85% of the PTCA group and in 92% of those with re-CABG (p = NS). During the hospital stay the complication rates were lower in the PTCA group. Actuarial survival was different at follow up (p = 0.04). Both PTCA and re-CABG groups resulted in equivalent event-free survival (freedom from death, myocardial infarction, unstable angina and urgent revascularization). The need for repeat revascularization at follow up was significantly higher in the PTCA group (PTCA 28% vs re-CABG 10%, p < 0.01). CONCLUSIONS: In this non-randomized study of patients with previous CABG requiring revascularization procedures, PTCA resulted in lower procedural morbidity and mortality risks. At follow up, both PTCA or CABG were similar for event-free survival; PTCA offered lower overall mortality, although it is associated to a greater need for subsequent revascularization procedures.

Aged↗

PubMed1997

Osteopontin regulation in cultured rat renal epithelial cells.

Osteopontin is a secreted, arginine-glycine-aspartate (RGD)-containing phosphoprotein that is up-regulated in kidney cortical tubular epithelial cells in many experimental models of tubulointerstitial fibrosis. Its close association with infiltrating macrophage in this disease and its ability to directly stimulate macrophage migration has made it a key target as a molecule likely to be important in mediating renal inflammation. The mechanism responsible for osteopontin up-regulation in kidney disease is unknown, but may involve induction by specific cytokines released by damaged glomeruli or other parts of the kidney, prior to the onset of interstitial disease. We have investigated this hypothesis by testing the effects of angiotensin II, bFGF, TGF beta 1, EGF, and IGF, important renal cytokines, on osteopontin regulation in cultured NRK52E cells, a rat renal epithelial cell line. Using Northern blot, Western blot, and ELISA analyses, we find that NRK52E cells constitutively express low levels of osteopontin mRNA and protein. TGF beta 1 and EGF are potent inducers of osteopontin mRNA and protein in those cells. mRNA stability and nuclear run on assays suggest that induction of osteopontin expression by TGF beta 1 and EGF is via increased transcription of the osteopontin gene. In contrast, IGF-1, angiotensin II, and PDGF BB did not significantly modulate osteopontin expression in NRK52E cells. These studies are consistent with the hypothesis that release of potent cytokines by the injured kidney might be one mechanism whereby elevated levels of osteopontin are synthesized by cortical tubular epithelial cells early in tubulointerstitial disease.

Animals↗

PubMed1997

[The prognostic significance of late potentials in patients with chronic coronary disease].

OBJECTIVE: The prognostic value of late potentials (LP) in the subacute phase of myocardial infarction (MI) is well known, but its prognostic value in long-standing coronary disease (LSCD) has not yet been established. In a population with LSCD we searched for a relation between the presence of LP in signal-averaged ECG (SAECG) performed before cardiac catheterization, and the incidence of cardiac events. METHODS: Based on our department's casuistics, we selected 50 consecutive patients with coronary disease confirmed by an angiogram and LP, and a control group without LP, in SAECG. We selected 91 men and nine women with an average age of 59 +/- 8 years. None of the patients had had ischemic events or revascularization procedures, in the 3 month period before catheterization. The follow-up was made between the time of the SAECG and the last medical visit. The events recorded were: ventricular arrhythmia, cardiac death, coronary angioplasty, coronary artery by-pass graft, MI or unstable angina. RESULTS: During a follow-up period of 20.1 +/- 8 months, we found no statistically significant difference between the two groups, regarding the incidence of such events. However, there was a higher incidence of ventricular arrhythmic events in the group with LP (four patients with ventricular tachycardia against none in the control group). All patients with ventricular tachycardia had had a previous MI. CONCLUSIONS: In this study, the presence of LP in SAECG did not have the same prognostic value found in the subacute phase of MI, but a higher incidence of arrhythmic events was observed in the group with LP and a previous MI.

Adult↗

PubMed1997

Longstanding traumatic tricuspid regurgitation with severe right ventricular failure.

A very unusual case of traumatic tricuspid regurgitation is reported, with severe symptoms of right ventricular failure, extreme dilatation of the right heart, echocardiographic and angiographic criteria of major tricuspid regurgitation, and severe right ventricular systolic dysfunction. The patient was referred for heart transplantation, on the assumption that conventional surgery was not possible. After careful evaluation, as the patient had normal pulmonary artery pressure and resistance, a tricuspid valve was replaced with good surgical outcome.

Accidents, Traffic↗

PubMed1997