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Biomedical subjects

I Palacios

Publications and source records attributed to I Palacios.

At least 19 recordsLinked to original sources

Pathological effects of alcohol septal ablation for hypertrophic obstructive cardiomyopathy.

BACKGROUND: The pathological effects and the mechanisms of action of intracoronary administration of ethanol for alcohol septal ablation (ASA) for the management of hypertrophic obstructive cardiomyopathy (HOCM) are unknown. METHODS: We examined surgical specimens and, in one case, autopsy specimens from four patients who underwent surgical septal myectomy 2 days to 14 months after unsuccessful ASA. RESULTS: Pathological examination early after ASA showed coagulative necrosis of both the myocardium and the septal perforator arteries. Affected arteries were distended and occluded by necrotic intraluminal debris, without platelet-fibrin thrombi. Late after unsuccessful ASA, excised septal tissue was heterogeneous, containing a region of dense scar, and adjacent tissue containing viable myocytes and interspersed scar. CONCLUSIONS: Intracoronary administration of ethanol in patients with HOCM causes acute myocardial infarction with vascular necrosis. The coagulative necrosis of the arteries, their distension by necrotic debris and the absence of platelet-fibrin thrombi distinguish ethanol-induced infarction from that caused by atherosclerotic coronary artery disease. The direct vascular toxicity of ethanol may be an important aspect of the mechanism of successful ASA.

Adolescent↗

Histopathological correlation of cartilage swelling detected by magnetic resonance imaging in early experimental osteoarthritis.

OBJECTIVE: We previously reported that an increase of cartilage thickness is the earliest measurable change by magnetic resonance imaging (MRI) in early stages of experimental osteoarthritis (OA). Our present objective was to study the microscopic translation of this finding in order to know whether the cartilage thickness increment represents the earliest structural damage or whether it alternatively constitutes a non-progressive reversible phenomenon. METHODS: OA was induced by partial medial meniscectomy in rabbits. Normal and sham-operated animals were used as controls. Gross and microscopic cartilage changes were sequentially assessed after surgery at 0, 2, 4, 6, 8, 10 and 52 weeks, and compared to MRI findings. RESULTS: The swelling of cartilage detected by MRI correlated with depletion in matrix proteoglycans and cellular loss, which were closely related to the progression of OA at the earliest stages. Abnormalities of the cartilage structure appeared only in advanced OA. CONCLUSION: Cartilage swelling detected by MRI is due to proteoglycan depletion and represents the earliest abnormality in OA. Because it is accompanied by cellular loss, it cannot be merely attributed to surgical trauma and represents true tissue damage. The biological meaning of volume variations detected by MRI should be assessed carefully taking into account the disease stage as an increase in cartilage height also reflects cartilage damage and not a reparative process.

Animals↗

Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

Animals↗

Modulation of cell recruitment by anti-inflammatory agents in antigen-induced arthritis.

OBJECTIVE: To study the effect of meloxicam (MXC) and diclofenac (DCF) on the recruitment of leucocytes during acute experimental arthritis. METHODS: Rabbits with antigen-induced arthritis were treated with MXC, DCF, or not treated. After 48 hours, synovial fluid (SF) leucocyte influx and prostaglandin E(2) (PGE(2)) levels were evaluated. Interleukin 8 (IL8) and monocyte chemotactic peptide-1 (MCP-1) expression and synthesis were studied in the inflamed tissues. RESULTS: Arthritic knees showed synovial effusion with a high leucocyte count and PGE(2) concentration, and an increased expression of IL8 and MCP-1. Both non-steroidal anti-inflammatory drugs (NSAIDs) reduced PGE(2) levels and the polymorphonuclear cell (PMN) concentration in SF, while the mononuclear cell (MN) concentration was unchanged in the treated groups in comparison with controls. A definite reduction of IL8 levels was obtained with the treatments, but the drugs did not prevent the up regulation of MCP-1. CONCLUSION: The effect of these NSAIDs in acute arthritis may be related to the down regulation of IL8 production. The results suggest a differential effect of anti-inflammatory drugs on PMN and MN recruitment to the joint.

Animals↗

Dimerization of the 3'UTR of bicoid mRNA involves a two-step mechanism.

The proper localization of bicoid (bcd) mRNA requires cis-acting signals within its 3' untranslated region (UTR) and trans-acting factors such as Staufen. Dimerization of bcd mRNA through intermolecular base-pairing between two complementary loops of domain III of the 3'UTR was proposed to be important for particle formation in the embryo. The participation in the dimerization process of each domain building the 3'UTR was evaluated by thermodynamic and kinetic analysis of various mutated and truncated RNAs. Although sequence complementarity between the two loops of domain III is required for initiating mRNA dimerization, the initial reversible loop-loop complex is converted rapidly into an almost irreversible complex. This conversion involves parts of RNA outside of domain III that promote initial recognition, and dimerization can be inhibited by sense or antisense oligonucleotides only before conversion has proceeded. Injection of the different bcd RNA variants into living Drosophila embryos shows that all elements that inhibit RNA dimerization in vitro prevent formation of localized particles containing Staufen. Particle formation appeared to be dependent on both mRNA dimerization and other element(s) in domains IV and V. Domain III of bcd mRNA could be substituted by heterologous dimerization motifs of different geometry. The resulting dimers were converted into stable forms, independently of the dimerization module used. Moreover, these chimeric RNAs were competent in forming localized particles and recruiting Staufen. The finding that the dimerization domain of bcd mRNA is interchangeable suggests that dimerization by itself, and not the precise geometry of the intermolecular interactions, is essential for the localization process. This suggests that the stabilizing interactions that are formed during the second step of the dimerization process might represent crucial elements for Staufen recognition and localization.

3' Untranslated Regions↗

Cartilage and bone biological markers in the synovial fluid of osteoarthritic patients after hyaluronan injections in the knee.

OBJECTIVE: To evaluate synovial fluid levels of cartilage and bone biological markers after repetitive intra-articular injections of sodium hyaluronate (HA) in knee osteoarthritis (OA) patients. METHODS: Twenty patients with knee OA were evaluated before and after 5 weekly injections of HA. To study cartilage and bone biological markers, synovial fluid and urine samples were collected simultaneously with the first (FI=week 0) and before the last injection (LI=week 4) of HA. Not commercially available markers (cartilage oligomeric matrix protein (COMP), proteoglycan monomers and cyanogen bromide peptide 11 of the type II collagen chains (alpha (II) CA11B)) were determined by an indirect inhibition ELISA developed and standardized in our laboratory. RESULTS: We found a significant reduction in levels of proteoglycan monomers (30+/-16 vs. 22+/-10 microg/ml, p<0.05), an increase in COMP concentration (2.9+/-0.9 vs. 3.6+/-0.9 microg/ml, p<0.05) and osteocalcin (BGP) levels (8.7+/-8 vs. 11.9+/-9 ng/ml, p<0.05). No significant changes were observed in the levels of alpha (II)CB11B), metalloproteinase-1 (MMP-1) or pyridinium cross-link/creatinine (Pyr/Cr). CONCLUSIONS: HA could elicit an indirect response on the cartilage and bone metabolism due to the increased overuse of the joint caused by the analgesic effect of HA. However, a direct HA action on the metabolism of chondrocytes must not be ruled out.

Aged↗

Argentine Randomized Study: Coronary Angioplasty with Stenting versus Coronary Bypass Surgery in patients with Multiple-Vessel Disease (ERACI II): 30-day and one-year follow-up results. ERACI II Investigators.

OBJECTIVE: The purpose of this study was to compare percutaneous transluminal coronary revascularization (PTCR) employing stent implantation to conventional coronary artery bypass graft surgery (CABG) in symptomatic patients with multivessel coronary artery disease. BACKGROUND: Previous randomized studies comparing balloon angioplasty versus CABG have demonstrated equivalent safety results. However, CABG was associated with significantly fewer repeat revascularization procedures. METHODS: A total of 2,759 patients with coronary artery disease were screened at seven clinical sites, and 450 patients were randomly assigned to undergo either PTCR (225 patients) or CABG (225 patients). Only patients with multivessel disease and indication for revascularization were enrolled. RESULTS: Both groups had similar clinical demographics: unstable angina in 92%; 38% were older than 65 years, and 23% had a history of peripheral vascular disease. During the first 30 days, PTCR patients had lower major adverse events (death, myocardial infarction, repeat revascularization procedures and stroke) compared with CABG patients (3.6% vs. 12.3%, p = 0.002). Death occurred in 0.9% of PTCR patients versus 5.7% in CABG patients, p < 0.013, and Q myocardial infarction (MI) occurred in 0.9% PTCR versus 5.7% of CABG patients, p < 0.013. At follow-up (mean 18.5 +/- 6.4 months), survival was 96.9% in PTCR versus 92.5% in CABG, p < 0.017. Freedom from MI was also better in PTCR compared to CABG patients (97.7% vs. 93.4%, p < 0.017). Requirements for new revascularization procedures were higher in PTCR than in CABG patients (16.8% vs. 4.8%, p < 0.002). CONCLUSIONS: In this selected high-risk group of patients with multivessel disease, PTCR with stent implantation showed better survival and freedom from MI than did conventional surgery. Repeat revascularization procedures were higher in the PTCR group.

Aged↗

High-resolution MRI detects cartilage swelling at the early stages of experimental osteoarthritis.

OBJECTIVE: The progressive early changes in cartilage and subchondral bone in an experimental model of osteoarthritis (OA) were investigated with high-resolution magnetic resonance imaging (MRI) and microradiography. METHODS: Partial medial meniscectomy was performed in the left knee of 16 rabbits. Four normal and four sham-operated additional rabbits were used as controls. Changes in cartilage and subchondral bone were sequentially assessed after surgery with MRI at 0, 2, 4, 6, 8 and 10 weeks, subchondral bone variations quantified postoperatively on microradiographs of sagittal sections at 6 and 10 weeks and the macroscopic alterations graded according to the severity of joint changes. RESULTS: MRI demonstrated a progressive increase in the articular cartilage thickness in the weight-bearing area of the femur at weeks 4, 6 and 8 vs basal. Tibial cartilage thickness only showed a significant increment at week 6. No significant abnormalities were detected on X-rays in subchondral bone when compared to controls. Macroscopically, 4 weeks after the operation OA rabbits had only slight cartilage discoloration. Cartilage eburnation, pitting, superficial erosions and osteophytes were detected at week 6. These abnormalities were more evident at 8 and 10 weeks after meniscectomy. CONCLUSION: The focal increase in cartilage thickness is one of the earliest measurable changes in OA and preceeds subchondral bone remodeling. The measurement of cartilage thickness variations with MRI can be used to follow the course of OA and to evaluate the potential beneficial effect of novel therapies.

Animals↗

Cyclosporin A prevents the histologic damage of antigen arthritis without inducing fibrosis.

OBJECTIVE: To study the effects of cyclosporin A (CSA) in a model of rheumatoid arthritis (RA) and the activation of growth factors related to pannus development at the site of injury. METHODS: Antigen arthritis was induced in the knees of 14 New Zealand rabbits, and the animals were randomized into 2 therapeutic groups: CSA at 10 mg/kg/day and CSA solvent. After 3 weeks of treatment, the rabbits were killed, and synovial tissues were obtained and compared with healthy specimens with regard to histopathologic lesions, deposition of transforming growth factor beta (TGFbeta) and collagens, and messenger RNA expression of platelet-derived growth factor B (PDGF-B) and TGFbeta. The effect of CSA on the expression of TGFbeta and PDGF-B was also examined in cultured synovial cells. RESULTS: CSA administration alleviated the histologic damage and avoided the overdeposition of matrix elements in the injured tissue. It was also able to normalize the enhanced expression of TGFbeta and PDGF-B observed in the untreated rabbits. Despite this modulation found in vivo, CSA up-regulated in a dose-dependent manner the gene expression of both trophic factors by healthy cultured synovial cells. CONCLUSION: The present study shows that continuous administration of CSA prevents the development of chronic synovitis in an experimental model of RA. As reported in other cell types, CSA promoted TGFbeta transcription by synovial cells in vitro, but failed to display a profibrogenic effect in the inflamed environment.

Animals↗

Changes in the pattern of fibronectin mRNA alternative splicing in acute experimental mesangioproliferative nephritis.

Fibronectins (FN) regulate cell migration, proliferation, and matrix formation during tissue injury. In humans, up to 20 different FN isoforms are generated by alternative splicing in three regions called EIIIA, EIIIB, and V, which have been implicated in the process undergoing wound healing and embryonic development. Specifically, EIIIA- and EIIIB-containing isoforms have been implicated in the regulation of cell proliferation and migration, whereas FN isoforms containing the full-length V region (named V120) are ligands to the VLA-4 integrin. To study the changes in the expression of FN isoforms in the anti-Thy-1 nephritis, an acute and self-resolutive model of mesangioproliferative nephritis, we analyzed the FN splicing patterns by means of ribonuclease protection assays. At Day 7 after anti-Thy-1 monoclonal injection, time of the maximal matrix expansion and glomerular hypercellularity, EIIIA+, EIIIB-, and V120 FN mRNA isoforms were increased. In accordance with the mRNA studies, FN proteins, including the EIIIA and V120 regions, increased in the mesangium of nephritic rats, as assayed by immunohistochemistry. Coinciding with the EIIIA and V120 isoforms up-regulation, there was an increase in mesangial cell proliferation and in the number of VLA-4+ infiltrating cells. At Day 14, in parallel with a remission of the above-mentioned changes, there was a decline in the mRNA and protein FN isoforms increased in the previous phase. The marked and reversible changes in the pattern of FN isoforms and their temporal association with other indicators of glomerular injury suggest that certain FN isotypes are important and coordinated components of the mechanisms attempting to reverse glomerular damage.

Acute Disease↗

A platelet activating factor receptor antagonist prevents the development of chronic arthritis in mice.

OBJECTIVE: To examine the effect of treatment with the platelet activating factor (PAF) receptor antagonist BN 50730 on the clinical and morphological evolution of collagen induced arthritis in mice. METHODS: Mice with collagen induced arthritis were treated with BN 50730 (0.3, 1, 3 mg/kg) or vehicle (0.1% Tween-20 in saline) once a day, from 3 days before the induction of the arthritis to 70 days after. Disease evolution was followed daily by inspection of inflammatory signs and measurement of the knee joint diameter on Days 0, 40, and 70. At the end of the treatment period, the morphological evaluation of the synovial membrane, the immunodetection of fibronectin, and the content of cartilage proteoglycans were studied. RESULTS: On Day 40, mice receiving the highest dose of BN 50730 (3 mg/kg) showed a reduction in the knee joint diameter in comparison with untreated (2.1 +/- 0.2 vs 2.8 +/- 0.4 mm, p < 0.01). On Day 70, animals receiving 1 and 3 mg/kg had a normal knee diameter, while it remained enlarged in the untreated ones. In BN 50730 treated mice (3 mg/kg) we also observed a significant reduction of the inflammation score (0.1 +/- 0.1 vs 2.5 +/- 0.2 in the untreated) and deposition of fibronectin. Depletion of cartilage proteoglycans was also reversed with BN 50730. CONCLUSION: The beneficial effects in this model of joint injury after administration of the PAF antagonist BN 50730 suggest that PAF could be implicated in the pathogenesis of chronic arthritis.

Animals↗

In-hospital and late results of coronary stents versus conventional balloon angioplasty in acute myocardial infarction (GRAMI trial). Gianturco-Roubin in Acute Myocardial Infarction.

One hundred four patients presenting with acute myocardial infarction < 24 hours after onset were randomized to 2 groups: group I (n = 52) was treated with balloon angioplasty followed electively with Gianturco Roubin II stents, and group II was treated with conventional balloon angioplasty alone (n = 52). All lesions were suitable for stenting. Baseline clinical, demographic, and angiographic characteristics were similar in the 2 groups. Procedural success was defined as no laboratory death or emergent coronary bypass, Thrombolysis In Myocardial Infarction (TIMI) trial 2 or 3 flow after the procedure in a culprit vessel, and a residual stenosis < or = 30% for coronary angioplasty and < 20% for stent. Procedural success was 98% in group I versus 94.2% in group II, p = NS. Thirteen patients in group II (25%) had bailout stenting during the initial procedure. Adverse in-hospital events including either death, nonelective coronary bypass, recurrent ischemia, and reinfarction occurred in 3.8% in group I versus 19.2% in group II, p = 0.03. Repeat angiography performed routinely before hospital discharge revealed TIMI 3 flow in the infarct-related artery in 98% in group I versus 83% in group II, p < 0.03. At late follow-up, event-free survival was significantly better in the stent (83%) than in the coronary angioplasty (65%) group (p = 0.002). The procedural in-hospital and late outcomes of this randomized study demonstrate that balloon angioplasty followed electively by coronary stents can be used as the primary modality for patients undergoing coronary interventions for acute myocardial infarction, increasing TIMI 3 flow, reducing in-hospital adverse events, and improving late outcome compared with balloon angioplasty alone.

Adult↗

In vitro systems for the reconstitution of snRNP and protein nuclear import.

In this chapter we have presented the most recent methods for the preparation of cell extracts and recombinant protein factors for the reconstitution of nuclear protein and snRNP import in vitro. In addition, we have discussed methods available for the quantitation of the level of import into nuclei. Accurate quantitation is particularly important when the effects of inhibitors are to be compared and when estimates of nuclear import rate are required.

Animals↗

Tenidap decreases IL-8 and monocyte chemotactic peptide-1 (MCP-1) mRNA expression in the synovial tissue of rabbits with antigen arthritis and in cultured synovial cells.

Since IL-8 and MCP-1 are chemoattractant proteins that participate in the recruitment of inflammatory cells into the arthritic joint, we examined the effects of tenidap, a new anti-inflammatory drug of the oxindole family, on IL-8 and MCP-1 expression in the joints of rabbits with acute antigen arthritis. The model was induced by injecting 5 mg/ml ovalbumin into the knees of 20 preimmunized rabbits. Animals were randomized into two groups: treated with tenidap (15 mg/kg per 12 h), or untreated. The effect of tenidap treatment was evaluated on chemokine production in synovial membranes of rabbits with arthritis and in cultured monocytic and synovial cells (SC). By immunoperoxidase staining, chemokines were localized in the synovial tissue. Chemokine messenger RNA levels in the synovial membranes and in cultured cells were analysed by reverse transcription-polymerase chain reaction (RT-PCR). At the end of the study, tenidap significantly reduced neutrophil infiltration into the joint cavity (27+/-4 x 10(6) cells/ml versus 45+/-6 x 10(6) cells/ml in untreated; P<0.05), and synovial effusion (134+/-15 microl versus 236+/-19 microl in untreated; P<0.005). Untreated rabbits showed synovial membrane up-regulation in mRNA expression of IL-8 and MCP-1 (11- and seven-fold versus healthy rabbits, respectively) that was markedly decreased by tenidap (two- and three-fold versus healthy rabbits, respectively). IL-8 and MCP-1 were localized in the synovial tissue in a perivascular pattern and areas of the interstitium and lining, mostly coinciding with cell infiltration. Tenidap also reduced the accumulation of IL-8 and MCP-1 proteins. In cultured synovial and monocytic cells, tumour necrosis factor-alpha (TNF-alpha) elicited an increase in gene expression of IL-8 (four- and nine-fold, respectively) and MCP-1 (nine- and four-fold, respectively) that was significantly reversed in both cell types by 10 microM tenidap. These results suggest that the beneficial effect of tenidap in acute antigen arthritis could be related to the down-regulation in gene expression and synthesis of IL-8 and MCP-1, two key chemokines involved in the recruitment of inflammatory cells.

Acute Disease↗

Acute Occlusion During Coronary Interventions: The Changing Pattern in the Era of Stents.

Acute procedural Occlusion continues to be a major cause of morbidity and mortality associated with coronary interventions. The incidence, management, and clinical outcomes of procedural occlusion of 2,138 patients undergoing coronary intervention were analyzed. The acute occlusion rate increased from 5.2% in 1994 to 8.0% in 1995 (p = 0.001). The success rate for managing such acute procedural occlusion improved significantly from 93% in 1994 to 100% in 1995 (p = 0.003). The composite endpoints of coronary artery bypass surgery, non-fatal myocardial infarction or death decreased from 16.4% in 1994 to 11.4% in 1995 (p = ns). The increased acute procedural occlusion rate in 1995 likely represents a more aggressive approach on more complex lesion types as well as higher total numbers of evolving myocardial infarctions, while the improvement in successful management of acute occlusion probably represents increased utilization of stents, improved and modified procedural technique and better antiplatelet/anticoagulation therapy.

Journal Article↗

Nuclear import of U snRNPs requires importin beta.

Macromolecules that are imported into the nucleus can be divided into classes according to their nuclear import signals. The best characterized class consists of proteins which carry a basic nuclear localization signal (NLS), whose transport requires the importin alpha/beta heterodimer. U snRNP import depends on both the trimethylguanosine cap of the snRNA and a signal formed when the Sm core proteins bind the RNA. Here, factor requirements for U snRNP nuclear import are studied using an in vitro system. Depletion of importin alpha, the importin subunit that binds the NLS, is found to stimulate rather than inhibit U snRNP import. This stimulation is shown to be due to a common requirement for importin beta in both U snRNP and NLS protein import. Saturation of importin beta-mediated transport with the importin beta-binding domain of importin alpha blocks U snRNP import both in vitro and in vivo. Immunodepletion of importin beta inhibits both NLS-mediated and U snRNP import. While the former requires re-addition of both importin alpha and importin beta, re-addition of importin beta alone to immunodepleted extracts was sufficient to restore efficient U snRNP import. Thus importin beta is required for U snRNP import, and it functions in this process without the NLS-specific importin alpha.

Biological Transport↗

Antifibroproliferative effect of tenidap in chronic antigen-induced arthritis.

OBJECTIVE: To determine whether tenidap regulates extracellular matrix metabolism in chronic arthritis. METHODS: Antigen arthritis was induced in the knees of 30 rabbits. Animals were distributed into 3 groups: untreated, tenidap-treated, and diclofenac-treated rabbits. Three weeks after disease induction, synovial membranes were extracted and processed for histopathologic examination and detection of type I collagen (CI) and fibronectin (FN) by immunoperoxidase. Simultaneously, we analyzed the in vitro effect of tenidap on healthy synovial cell (SC) proliferation, FN expression and synthesis, and expression of transforming growth factor beta1 (TGFbeta1) messenger RNA. RESULTS: Untreated animals showed synovial lining hyperplasia, cellular infiltration at the sublining, and increased deposition of matrix proteins. These findings were not apparent in tenidap-treated rabbits, where CI and FN had the same distribution as in healthy synovial membranes. In vitro, tenidap inhibited SC proliferation (> or =25 microM) and down-regulated the expression and synthesis of FN in a dose-dependent manner (> or =1 microM). This antifibrotic effect was associated with a reduction of TGFbeta1 message. CONCLUSION: Tenidap down-regulates the fibroproliferative changes typical of chronic arthritis, an effect that fits the profile of a disease-modifying agent for rheumatoid arthritis.

Animals↗