Biomedical subjects

A Pérez

Publications and source records attributed to A Pérez.

At least 19 recordsLinked to original sources

PubMed2006

The influence of wire positioning upon the initial stability of scaphoid fractures fixed using Kirschner wires A finite element study.

A finite element model of the carpal scaphoid and its joints was developed to study how wire positioning affects the initial stability of the fixation of scaphoid waist fractures using Kirschner wires. A transverse fracture of the scaphoid waist was simulated along with its fixation using five different two-wire configurations. The resulting models were subjected to a load simulating a 200N force passing through the wrist. Friction between bony fragments was taken into account; as the friction coefficient of cancellous bone is unknown, three different values were analysed. For each of these friction coefficient values, the smallest transverse interfragmentary displacements, and consequently maximum initial stability, were obtained for the model that simulated the maximum gap between wires in the plane of fracture. Results also show that for a similar gap in the plane of fracture, more stable fixation can be achieved when wires cross each other not only in the frontal plane of the hand, but also perpendicularly to it.

Bone Wires↗

PubMed2006

Efficacy of aminocaproic, tranexamic acids in the control of bleeding during total knee replacement: a randomized clinical trial.

BACKGROUND: Risks and costs of allogeneic blood transfusions mandate strategies to reduce blood loss in surgery. The objective of this study was to assess the efficacy of antifibrinolytic treatment in reducing perioperative blood loss during total knee replacement. METHODS: A double-blind, randomized and placebo-controlled clinical trial was carried out on 127 patients undergoing total knee replacement. Patients in the study group received tranexamic acid 10 mg kg(-1) i.v. just before the tourniquet was deflated and 3 h later, or epsilon-aminocaproic acid 100 mg kg(-1) before tourniquet deflation followed by continuous perfusion (1 g h(-1)) during 3 h. External perioperative blood loss was measured and total blood loss was calculated. The number of patients transfused and number of packed red cell (PRC) units transfused was recorded and possible postoperative thromboembolic complications were investigated. RESULTS: Total blood loss [mean (sd)] was 1099 ml (535) in the group that received antifibrinolytic agents and 1784 ml (660) in the control group (P<0.001). Five patients (7.5%) in the study group and 23 (38.3%) in the control group (P<0.001) received blood transfusions; the first group received a mean of 0.10 PRC unit per patient and the second, 0.58 (P<0.001). Mean reduction in haemoglobin levels (g dl(-1)) between preoperative and fifth day postoperative readings was 2.5 (0.9) in the study group and 3.4 (1.2) in the control group (P<0.001). Clinical assessment did not reveal any thromboembolic complications. CONCLUSIONS: Antifibrinolytic agents produce a significant decrease in blood loss in patients undergoing total knee replacement, reflected in a reduction in the number of blood transfusions required.

Aged↗

PubMed2006

Postprandial thrombin activatable fibrinolysis inhibitor and markers of endothelial dysfunction in type 2 diabetic patients.

The aim of this study was to assess postprandial changes in thrombin activatable fibrinolysis inhibitor (TAFI) antigen, a thrombin-dependent fibrinolysis inhibitor with anti-inflammatory properties, and soluble markers of endothelial dysfunction in normotriglyceridemic type 2 diabetic patients. Fasting and postprandial TAFI antigen, thrombomodulin, tissue factor pathway inhibitor (TFPI), and plasminogen activator inhibitor 1 were assessed in 12 normotriglyceridemic type 2 diabetic patients treated with diet (hemoglobin A1c, 6.80% +/- 0.67%) and 14 controls. Fasting low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, free fatty acids and apolipoprotein B, and fasting and postprandial triglyceride, glucose, and insulin were also measured. Fasting TAFI was higher in the control group (102% +/- 16.9% vs 72.9% +/- 15.9%; P < .0005) and was inversely correlated with glycemic control. It decreased 4 hours after the meal (31.8% reduction [P < .005] for controls and 12.6% [P < .05] for diabetic patients) and returned to fasting levels after 8 hours. This decrement was correlated with fasting TAFI, glucose and hemoglobin A1c, and the area under the curve of glucose. Thrombomodulin, TFPI, and plasminogen activator inhibitor 1 were similar in both groups, with thrombomodulin and TFPI showing a transient postprandial increase. A fat-rich meal produces a transient increase in markers of endothelial dysfunction and a temporary reduction in TAFI, an anti-inflammatory molecule whose concentration is low in type 2 diabetes mellitus.

Apolipoproteins B↗

PubMed2006

[The vacuum chest wall lifter in the treatment of pectus excavatum].

Since 2002, the Eckart Klobe vacuum has been used in our Service as an innovate and non-invasive procedure in patients with pectus excavatum. This vacuum method contributes not only to hold promise as a valuable adjunct in minimally invasive surgery, but also as an effective method to lift and fix the funnel for repairing pectus excavatum in some patients. Our experience is limited to the use of this device in 10 patients, during the Nuss technique. This procedure has been useful for safer passage of the introducer, and as a definitive treatment in a 10 years old girl with pectus excavatum and a Haller index of 5.1 with successful result after one year of treatment. The aim of this study is to report the safety and efficacy of this procedure in appropriate patients. Long-term results will be necessary to confirm this method as an alternative to more invasive techniques.

Child↗

PubMed2005

The inflammatory properties of electronegative low-density lipoprotein from type 1 diabetic patients are related to increased platelet-activating factor acetylhydrolase activity.

AIMS/HYPOTHESIS: Chemical and biological characteristics of LDL(-) from type 1 diabetic subjects were analysed. The diabetic patients were studied during poor and optimised glycaemic control. MATERIALS AND METHODS: Total LDL was subfractionated into electropositive LDL(+) and electronegative LDL(-) by anion exchange chromatography and the lipid and protein composition of the two determined. RESULTS: LDL(-) differed from LDL(+) in that it had higher triglyceride, non-esterified fatty acids, apoE, apoC-III and platelet-activating factor acetylhydrolase (PAF-AH), as well as lower apoB relative content. No evidence of increased oxidation was observed in LDL(-). LDL(-) increased two-fold the release of interleukin 8 (IL-8) and monocyte chemotactic protein 1 (MCP-1) in endothelial cells, suggesting an inflammatory role. Optimisation of glycaemic control after insulin therapy decreased the proportion of LDL(-), but did not modify the composition of LDL subfractions, except for a decrease in PAF-AH activity in LDL(-). The possibility that LDL(-) could be generated by non-enzymatic glycosylation was studied. Fructosamine and glycated LDL content in LDL subfractions from type 1 diabetic patients was greater than in LDL subfractions isolated from normoglycaemic subjects, and decreased after glycaemic optimisation in both subfractions. However, no difference was observed between LDL(+) and LDL(-) before and after insulin therapy. CONCLUSIONS/INTERPRETATION: These results provide evidence that LDL(-) is not produced by glycosylation. Nevertheless, LDL(-) from diabetic patients displays inflammatory potential reflected by the induction of chemokine release in endothelial cells. This proatherogenic effect could be related to the high PAF-AH activity in LDL(-).

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2005

Quantitative effect of glycaemic improvement on the components of diabetic dyslipidaemia: a longitudinal study.

In order to assess the effect of glycaemic improvement on lipoprotein concentrations, we studied 73 type 2 diabetic subjects before (HbA1c 10.1 (6.2-16)%) and after (HbA1c 6.6 (3.8-8.0)%) glycaemic improvement. Total triglyceride and cholesterol (c), LDLc, HDLc, non-HDLc and apolipoproteins AI (apoAI) and B (apoB) were measured. Bivariate correlations and step-wise, multivariate analysis were performed to find predictors of change in the different components of diabetic dyslipidaemia. Changes in HDLc (r = -0.358, P = 0.001), apoAI (r = -0.355, P = 0.003), apoAI/apoB ratio (r = -0.333, P = 0.005), weight (r = -0.245, P = 0.046) and BMI (r = -0.253, P = 0.039) correlated with that of HbA1c, but, in multivariate analysis, only changes in HDLc, apoAI and apoAI/apoB ratio were predicted by the decrease in HbA1c. For the median observed change in HbA1c (-3.3 percentage-points), the estimated changes were +0.14 mmol/l, +0.12 g/l and +0.20 for HDLc, apoAI and apoAI/apoB ratio, respectively, accounting for 81, 92 and 80% of the observed changes. In conclusion, for the component of diabetic dyslipidaemia for which less therapeutic tools are available, glycaemic improvement is most effective.

Aged↗

PubMed2005

The NK1 receptor is involved in the antitumoural action of L-733,060 and in the mitogenic action of substance P on neuroblastoma and glioma cell lines.

We have carried out an in vitro study to investigate the ability of substance P to activate cell growth and the NK1 receptor antagonist L-733,060 to inhibit cell growth in the SKN-BE(2) neuroblastoma and GAMG glioma cell lines. A coulter counter was used to determine viable cell numbers, followed by application of the tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)2-(4-sulfophenyl)-2H-tetrazolium], inner salt, colorimetric method to evaluate cell viability in this cytotoxicity assay. Nanomolar concentrations of substance P increased, and micromolar concentrations of L-733,060 inhibited the growth of both cell lines studied, with and without previous administration of substance P. In addition, we have demonstrated by immunoblot analysis that NK1 receptors are present in both cancer cell lines studied here. Thus, this study demonstrates that substance P acts as a mitogen in the SKN-BE(2) neuroblastoma and GAMG glioma cell lines, and that the antitumoural action of L-733,060 on both human cell lines occurs through the NK1 receptor. This action suggests that the NK1 receptor is a new and promising target in the treatment of human neuroblastoma and glioma.

Antineoplastic Agents↗

PubMed2005

[Advantages and characteristics of the laparoscopic approach in the elderly].

Both the age of the population and anesthetic and surgical techniques are advancing. Currently, 40% of surgical activity is performed in patients older than 65 years, who present a higher surgical risk than younger patients. The aim of treatment in the elderly is to provide the best possible quality of life, even though this represents a surgical challenge because of associated comorbidity and reduced cardiopulmonary reserve. From the moment at which laparotomy becomes an increased stress in the elderly, laparoscopic surgery can be particularly advantageous in this population. Therefore, minimally invasive surgery may have a greater impact in these individuals than in younger patients in reducing postoperative pain, cardiorespiratory complications, hospital stay, and recovery time before resuming physical activity. The recent advances in anesthesia, together with improved patient selection and perioperative cardiac care, and the general adoption of minimally invasive access have enabled more complex gastrointestinal procedures to be performed in the elderly. The factors that could influence the development of this type of approach in the elderly, as well as the precautions that should be taken, should be further analyzed.

Aged↗

PubMed2005

Cerebellar hematoma following transsphenoidal surgery.

Cerebellar hemorrhage after supratentorial surgery is a very infrequent complication. Most cases occur following aneurysm or brain tumor surgery, or evacuation of extracerebral collections. The underlying mechanism of formation of these hematomas is unclear. We present an example of cerebellar hemorrhage following transsphenoidal resection of a pituitary adenoma. To our knowledge, this is the first case reported of hemorrhage in the posterior fossa after a transsphenoidal approach.

Adenoma↗

PubMed2005

[Infectious complications after epidural analgesia to control pain after abdominal surgery].

Epidural abscess as a complication of spinal analgesia is rare, but because of its potential clinical implications it must always be watched for in patients who have undergone epidural procedures. The case we report is of interest because of the long latency period between removal of the catheter and the onset of clinical signs and because of the rarity of the pathogen implicated in forming the abscess (Candida albicans).

Ampulla of Vater↗

PubMed2004

Influence of exogenous insulin on C-peptide levels in subjects with type 2 diabetes.

AIM: The aim of this study was to determine whether the influence of insulin therapy on fasting and stimulated C-peptide levels in type 2 diabetic subjects is due to plasma glucose reduction or a direct effect of exogenous insulin. METHODS: Plasma glucose and serum C-peptide levels were determined before and after IV injection of 1mg glucagon on three separate days in 21 type 2 diabetic subjects. Day 1: without pharmacological treatment and fasting plasma glucose > 11.1 mmol/L; day 2: fasting plasma glucose 4.4-7.8 mmol/L, 1h after withdrawing intravenous regular insulin infusion; day 3: fasting plasma glucose 4.4-7.8 mmol/L with bed-time NPH insulin. RESULTS: Fasting and glucagon stimulated C-peptide levels were higher on day 1 than days 2 and 3. Fasting, but not stimulated C-peptide levels, were lower on day 3 than day 2. These differences were not appeared when the percentage of C-peptide increment or the C-peptide/glucose ratio were compared in the three days. CONCLUSIONS: Blood glucose reduction instead of exogenous insulin is responsible for the C-peptide decrease during insulin therapy in type 2 diabetic subjects.

Aged↗

PubMed2004

Pneumococcal bacteremia in children: an 8-year review in two hospitals in Barcelona.

In this study, 90 episodes of pneumococcal bacteremia that occurred over an 8-year period in two hospitals in Barcelona were analyzed retrospectively to determine the clinical and bacteriological characteristics of pneumococcal bacteremia, the risk factors for antibiotic resistance, the outcome, and the vaccine coverage. The mean age of the patients was 3.1 years and the male/female ratio was 1.7. The overall rates of penicillin-non-susceptible, cefotaxime-non-susceptible, and erythromycin-resistant isolates were 48.8, 24.4, and 25.5%, respectively. Antibiotic resistance was associated with children under the age of 2 years and with previous antibiotic treatment. The percentage of antibiotic resistance was higher in the nine episodes that occurred in patients with an underlying illness. The most prevalent serotypes identified were 1, 14, 6B, 18C, 5, and 19A. Serotypes 6A/B, 14, and 19A/F were isolated primarily from children under 2, whereas serotypes 1 and 5 were recovered more frequently from older children. Apparent relationships between serotypes 6A/B, 14, and 19A/F and occult bacteremia and between serotypes 1 and 5 and bacteremic pneumonia were confounded by the age variable. The proportion of bacteremic episodes preventable by all (7-valent, 9-valent, and 11-valent) of the conjugate pneumococcal vaccines was 60% in children under 2. In older children, the serotype coverage rate for the three formulations was 48, 87, and 87%, respectively. In summary, these data expand upon previous Spanish studies in which serotypes 1 and 5 were reported to be among the leading causes of severe systemic pneumococcal infections in children over 2, findings that should be taken into consideration when planning vaccine programmes.

Adolescent↗

PubMed2004

Rapid diagnosis of Staphylococcus aureus bacteremia using S. aureus PNA FISH.

In the study presented here, the performance of the S. aureus PNA FISH assay was evaluated using 285 blood cultures (from 104 patients) that had gram-positive cocci resembling staphylococci on Gram stain. The new molecular test is based on a fluorescence in situ hybridization assay using peptide nucleic acid probes targeting Staphylococcus aureus 16S rRNA and is designed for the rapid identification of Staphylococcus aureus directly from positive blood cultures. The sensitivity, specificity, and positive and negative predictive values of the S. aureus PNA FISH for the rapid identification of Staphylococcus aureus directly from positive blood culture bottles were 100, 99.4, 99.2 and 100%, respectively.

Bacteremia↗

PubMed2004

Superior gluteal nerve: safe area in hip surgery.

Injuries to the superior gluteal nerve are very bad complications in hip surgery. An exact knowledge of its course may be helpful in avoiding such problems. Nineteen half pelvises from ten male and female adult cadavers were dissected. Dissections revealed that the nerve divided into two (89.48%) or three (10.52%) branches after leaving the pelvis. The more caudal branch was responsible for innervation of tensor fascia latae. The distance and the angle from the entry points of all branches of the superior gluteal nerve into the deep surface of the gluteus medium and minimus muscles to the mid-point of the superior border of the greater trochanter were measured. The branch that innerved the tensor fascia latae was also followed. These data were subjected to several statistical tests. Based on these findings, and in order to prevent nerve damage, we propose to define a 2-3 cm safe area above the great trochanter.

Adult↗

PubMed2004

Emerging cardiovascular risk factors in subclinical hypothyroidism: lack of change after restoration of euthyroidism.

Subclinical hypothyroidism (SH) is a frequent condition that may be associated with increased cardiovascular risk. There is current interest in determining the effect, if any, of substitutive therapy with l-thyroxine (L-T4) on cardiovascular risk factors in SH and, particularly, on those associated with emerging cardiovacular risk, such as apolipoprotein (apo) B, lipoprotein (Lp) (a), total homocysteine (t-Hcy), and C-reactive protein (CRP). Thus, the aim of this study was to assess the impact of euthyroidism restoration on these emerging risk factors in SH. Forty-two patients diagnosed with SH were consecutively recruited before treatment. These patients were treated with L-T4 for 3 to 6 months with the dose necessary to restore euthyroidism. Lp(a), fasting and postmethionine (n = 28) t-Hcy, and CRP did not change with substitutive therapy, regardless of the respective baseline values, and the decrease in apo B paralleled that of low-density lipoprotein (LDL) cholesterol. Similarly, no treatment effect was observed on homocysteine or CRP in patients with thyrotropin-stimulating hormone (TSH) >10 mIU/L. Monitoring of emerging risk factors did not offer additional arguments for treating patients with SH and, thus, is not justified in their clinical management.

Adult↗

PubMed2004

Engraftment syndrome after autologous peripheral blood progenitor cell transplantation in pediatric patients: a prospective evaluation of risk factors and outcome.

We prospectively analyzed the incidence, risk factors and outcome of engraftment syndrome (ES) in 112 patients undergoing autologous peripheral blood progenitor cell transplantation with different malignancies between January 1999 and December 2003. The median age was 8 years (range 1-18). There were 73 males. There were 37 hematological neoplasias and 75 solid tumors. Disease status at transplantation was early in 49, intermediate in 15 and 48 in advanced phase. The median CD34+ cells infused was 4.6 x 10(6)/kg. With a median follow-up of 23 months (1-116 months), 38 patients developed ES. The cumulative incidence of ES was 34.5 +/- 4.5% and the event-free survival was 58.3 +/- 12%. There were no differences in the causes of death between patients with or without ES. A high number of CD34+ cells/kg infused, patients transplanted in early phase, the type of malignancy (solid tumor) and conditioning regimens other than busulfan based were significantly associated with ES in a multivariate analysis.

Adolescent↗

PubMed2004

Histoplasma capsulatum yeast cells attach and agglutinate human erythrocytes.

The ability of yeast cells of Histoplasma capsulatum to attach and agglutinate human erythrocytes has been described. This is the first report involving these yeasts in the hemagglutination phenomenon. Results revealed that the yeast cells were able to bind to erythrocytes irrespective of blood groups and to agglutinate them when a high density of yeast cells was used. Assays on the inhibition of yeast attachment to erythrocytes were also performed, using sugar-treated yeast cells. Results indicate that galactose (Gal), mainly the beta-anomer, specially inhibited yeast attachment. Disaccharides (Gal-derivatives) and glycosaminoglycans containing Gal residues, mainly chondroitin sulfate C, promote this type of inhibition. In addition, preliminary data of inhibition assays also involved a probable ionic strength driven mechanism mediated by sialic acid and heparan sulfate, suggesting that yeast binding to erythrocytes could be associated with negative charges of both molecules.

Blood Group Antigens↗

PubMed2004

HIV-infected children with moderate/severe immune-suppression: changes in the immune system after highly active antiretroviral therapy.

The objective of this study was to monitor the changes in the immune system of HIV-infected children with moderate or severe immunodeficiency after highly active antiretroviral therapy (HAART), comprising a follow-up study in 14 HIV-infected children on HAART at two time points separated approximately by 11.8 +/- 0.4 (9.9; 15.4) months. HIV-infected children had significantly lower TREC levels than the control group, but 1 year after HAART the levels increased significantly (P < 0.05). In contrast, viral load (VL) did not change significantly. A positive correlation between T cell receptor excision circle (TREC) levels and both CD4(+) T cell absolute counts (r = 0.558; P = 0.05) and percentages (r = 0.625; P = 0.030) was found. During follow-up on HAART, the percentages and absolute counts of naive CD4(+) and CD8(+) T cell subsets were increased significantly (P < 0.05). CD4(+) CD45RA(hi+) CD62L(+), CD4(+) CD45RA(+) and CD4(+) CD38(+) percentages, and the CD8(+) CD45RA(hi+) CD62L(+) counts reached similar values to the control group. Also, CD8(+) CD45RO(+) CD38(+) and CD8(+) CD45RO(+) percentages, and CD8(+) CD45RO(+) CD38(+) absolute counts (P < 0.05) decreased with respect to the baseline. Lymphoproliferative responses to pokeweed mitogen (PWM) before HAART were lower in HIV-infected children than the control group, but they recovered to normal levels after a year on HAART. Tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma production by PHA-activated peripheral blood mononuclear cells (PBMC) was lower before HAART (P < 0.001), but reached similar levels to the control group 1 year after HAART. In HIV-infected children IgG, IgG(1) and IgG(3) plasma levels decreased significantly after HAART. The immune system reconstitution induced by HAART in HIV-infected children seems to be the consequence of decreased immune system activation and naive T cell reconstitution, mainly of thymic origin.

Adolescent↗