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Biomedical subjects

B Pascual

Publications and source records attributed to B Pascual.

17 recordsLinked to original sources
PubMed2006

[Repetition of pseudo-words in Spanish children with specific language disorder: a psycholinguistic marker].

AIMS: To analyze whether repetition of nonwords (NWR) is a good method to differentiate between Spanish-speaking children with specific language impairment (SLI), children with normal language development (NL), and children with articulation disorder (AD), and to study whether phonological and syllabical characteristics, which are present in nonwords used in this task, are compatible with a SLI explanation on the basis of the temporal auditory limitation. PATIENTS AND METHODS: Eighteen 5- and 6-year-old children with NL, 19 with SLI, and 19 with AD, performed verbal tasks (principally, lexical and verbal memory tasks), and two NWR tasks: one is formed by four nonwords series with frequent syllables, in accordance with the analysis of syllable frequency in Spanish, and the other task is formed by nonwords with infrequent syllables. RESULTS: Like in English, NWR is the best method to differentiate children with SLI and children with NL; yet children with a minor impairment, like AD, show deficits in this task. Therefore, this disorder could be considered as an 'intermediate zone' between NL and SLI. Then it seems that AD is not an unmixed impairment of production only, since in its origin there are difficulties linked with the formation of the phonological representations of the words. CONCLUSIONS: With regard to syllable frequency, results do not support the explanation on the basis of temporal auditory limitation in Spanish. Results are discussed in relation to other explanations: general limitation of processing, with special incidence of the phonological working memory, and connectionist perspectives.

Articulation Disorders↗
PubMed2006

[Magnetic resonance in moderate and severe head injury: comparative study of CT and MR findings. Characteristics related to the presence and location of diffuse axonal injury in MR].

INTRODUCTION: Cranial CT has been the most extended evaluation means for patients suffering head trauma. However, it has low sensitivity in the identification of diffuse axonal injury and posterior fossa lesions. Cranial MR is a potentially more sensitive test but difficult to perform in these patients, a fact that has hampered its generalised use. OBJECTIVE: To compare the identification capability of traumatic intracranial lesions by both diagnostic tests in patients with moderate and severe head injury and to determine which radiological characteristics are associated with the presence of diffuse injury in MR and their clinical severity. MATERIAL AND METHODS: 100 patients suffering moderate or severe head injury to whom a MR had been performed in the first 30 days after trauma were included. All clinical variables related to prognosis were registered, as well as the data from the initial CT following Marshall et al., classification. The MR was blindly evaluated by two neuroradiologists that were not aware of the initial CT results or the clinical situation of the patient. All lesions were registered as well as the classification following the classification of lesions related to DAI described by Adams et al. CT and MR findings were compared evaluating the sensitivities of each test. Factors related to the presence of diffuse injury in MR were studied by univariate analysis using chi2 test and simple correlations. RESULTS: MR is more sensitive than CT for lesions in cerebral white matter, corpus callosum and brainstem. It also detects a greater number of cerebral contussions. The presence of diffuse axonal injury depends on the mechanism of the trauma, being more frequent in higher energy trauma, specially in traffic accidents. Among the radiological characteristics associated to DAI the most clearly related is intraventricular haemorrhage. The presence of a deeper injury and a higher score in the scales of Adams is associated with a lower score in the GCS and motor GCS, and so with a worse level of consciousness and bigger severity of injury, confirming Ommaya's model.

Adolescent↗
PubMed2005

[Oncolytic viral therapy of gliomas: review of the literature].

Gliomas are the most frequent primary tumors of the brain. The standard treatment includes surgery, radiotherapy and chemotherapy, but the outcomes of patients with these tumors have remained nearly unchanged for past years. Hopefully, recent advances in molecular biology are rising new clinical expectation for patients with brain tumors. Among the novel techniques in this new field of research a new field of research, the use of oncolytic viruses has been explored in different trials during last years. In the present review we analyze the advances in the understanding of the oncolytic viral therapy of gliomas.

Brain Neoplasms↗
PubMed2005

[Value of serial CT scanning and intracranial pressure monitoring for detecting new intracranial mass effect in severe head injury patients showing lesions type I-II in the initial CT scan].

OBJECTIVE: To determine the incidence of pathological and intracranial pressure (ICP) changes during the acute posttraumatic period in severe head injury patients presenting with lesions Types I-II (TCDB classification) in the admission CT scan with the aim of defining the most appropriate strategy of sequential CT scanning and ICP monitoring for detecting new intra-cranial mass effect and improving the final outcome. MATERIAL AND METHODS: 56 patients (ages 15-80 years) consecutively admitted during a 2 years period were included. All had the initial CT scan < 24 hours after injury (mean interval = 150 min), several CT controls within the first days of the course and ICP monitoring after admission. Different epidemiological, clinical and radiological variables were recorded and deterioration defined as the development of sustained ICP over 20 mmHg requiring aggressive medical and/or surgical treatment was considered the dependent variable. Uni and multivariate analyses were made for determining the correlation between different parameters and the occurrence of deterioration and the final outcome as assessed with the GOS. RESULTS: The mean GCS score was 5 and 37% of the patients showed pupillary changes; 52.3% had peritraumatic hypotension-hypoxemia, 16.1% anemia and 12.3% coagulation changes. 50% of the patients showed petechial hemorrhages in the white matter or the brainstem, 66% SAH, 40% HIV, 39.3% brain contusion and 21.4% small extraaxial hematomas. 57.1% of the patients showed CT changes through the acute post-traumatic period consisting of new contusion (26.8% of the cases), growing of previous contusion (68.2%) or previous extraaxial hematoma (10.7%), and generalized brain swelling (10.7%). 64.9% of the patients made a favourable and 35.7% an unfavourable outcome. Overall, 27 (48.9%) patients developed deterioration, 21 (37.5%) with concurrent CT changes and 6 (10.7%) without new pathology as seen by the CT control. The remaining 29 (51.7%) patients in this series did not develop deterioration in spite that 11(19.6%) showed CT changes. The age, the initial score, the occurrence of peritraumatic hypotension-hypoxemia and coagulation disorders did not correlate with the risk of deterioration. By contrast, the presence of contusion at the initial CT scan (p= 0.01) and the occurrence of CT change (only generalized brain swelling, p= 0.003) significantly correlated with the risk of deterioration; in his turn deterioration increased by a factor of 10 (OR = 9.8) the risk of death and 7 out of the 8 patients who died developed intractable intracranial hypertension. The 8 (14.2%) patients requiring surgery showed simultaneous ICP deterioration and CT changes, but another 11 patients in a similar condition could be managed without surgery. With or without ICP deterioration, patients showing CT changes had a worse outcome than those without new pathologies, but the difference did not reach statistical significance, DISCUSSION AND CONCLUSIONS: Over 50% of the patients with initial Type I-II lesions developed new CT changes and nearly 50% showed intracranial hypertension during the acute posttraumatic period. Considering the high incidences of ICP and CT deterioration through the course, along with the absence of strong predictors and the discordances between CT and ICP changes (which were seen in 30.3% of the cases) we recommend ICP monitoring after admission in all patients and serial CT scanning at 2-4, 12, 24, 48 and 72 hours after injury with additional controls as indicated by clinical or ICP changes in all cases. Though it is clear that the presence of severe intra-cranial hypertension significantly increased the risk of death, the small size of the sample in this series prevented to assess to what extent the occurrence of new mass effect and/or raised ICP contributed to the development of moderate and severe disability in the survivors which were mainly due to the occurrence of diffuse axonal injury. Finally, demonstrating that sequential CT scanning and ICP monitoring improve the final outcome in this type of patients would require a prospective randomized trial which is impracticable for different reasons, among them the ethical ones.

Adolescent↗
PubMed2002

Motor circuitry re-organization after pallidotomy in Parkinson disease: a neurophysiological study of the bereitschaftspotential, contingent negative variation, and N30.

The aim of the study was to evaluate the reorganization changes in the motor circuitry of the basal ganglia following unilateral posteroventral pallidotomy in Parkinson disease (PD) patients using neurophysiological paradigms. Eight advanced PD patients received a neurophysiological battery 2 months prior and 6 months after unilateral pallidotomy. Examinations were all performed in the practically defined "off" situation. Bereitschaftspotential (BP) and N30 were recorded for each hand alternately. Contingent negative variation (CNV) was obtained using a visual Go/no-Go paradigm. ANOVAs (electrode position; surgery) were applied for BP and CNV results. N30 data were analyzed using Wilcoxon matched-pair tests. A significant increase in amplitude of the late component (NS') of the BP was evidenced with patient performing with the hand contralateral to pallidotomy. No significant amplitude differences were found in CNV after surgery in any lead, or in any of the time windows tested. A trend toward significance was observed corresponding to a postsurgical numerical increase in amplitude of the N30 peak in the hand contralateral to pallidotomy. These results suggest that neurophysiological changes after pallidotomy are mainly in the last stages of movement preparation and execution.

Adaptation, Physiological↗
PubMed2000

Abnormalities of the acoustic startle reflex and reaction time in gilles de la tourette syndrome.

OBJECTIVE: To study the startle reflex and the effect of the startle reflex stimulus over reaction time (start-react effect) in Gilles de la Tourette syndrome (GTS). METHOD: Ten GTS patients and ten matched healthy volunteers underwent a simple RT paradigm (4 blocks of 50 trials). Forty acoustic startle reflex stimuli (110 dB) were randomly delivered with a 20% occurrence probability and presented unexpectedly at the same time as the imperative stimuli of the RT. Variables of interest were: amplitude, onset latency, degree of spread and rate of habituation of the startle response, and RT and the start-react effect caused by the startle stimuli. RESULTS: GTS patients showed a significantly higher amplitude, a major degree of spread and fewer habituation phenomena of the startle reflex. GTS patients showed poorer non statistically significant RT performance compared to controls, with a significant correlation between RT and severity of the disease. The start-react effect was significantly less pronounced in GTS patients. CONCLUSIONS: The present study confirms that GTS has an exaggerated startle reflex response and extend the spectrum of abnormalities to the start-react effect. A state of dopaminergic hyperactivity may have contributed to these results.

Adolescent↗
PubMed1999

Characterization of new acrylic bone cement based on methyl methacrylate/1-hydroxypropyl methacrylate monomer.

New formulations of acrylic bone cement based on methyl methacrylate/1-hydroxypropyl methacrylate (MMA/HPMA) monomers were developed with the purpose of obtaining more ductile materials with reduced polymerization shrinkage. In this way, the ductility of such materials increased, but the introduction of high percentages of the hydrophilic component produced an important decrease in Young's modulus and strength. To ascertain the reason for the deterioration of the tensile parameters, an analysis by scanning electron microscopy of these formulations was carried out; it revealed poor adhesion between the matrix and poly(MMA) beads. We also observed that the polymerization shrinkage increased as the amount of hydrophilic monomer in the formulation decreased, and the 50% (v/v) HPMA modified bone cement compensated for this volume reduction with its water uptake swelling. Measurements taken on the setting time and polymerization exotherm showed a decrease in the former and an increase in the latter, because of the introduction of a more reactive monomer in the bone cement formulation.

Bone Cements↗
PubMed1999

Modified acrylic bone cement with high amounts of ethoxytriethyleneglycol methacrylate.

One cause of arthroplasty failure is the brittle mechanical behavior of bone cements. However, the improvement of cement formulations must also be accompanied by the maintenance of a wide variety of characteristics. New bone cements were obtained by the substitution of high percentages, up to 60% (v/v), of methyl methacrylate (MMA) by a higher molecular weight and more hydrophilic monomer, ethoxytriethyleneglycol methacrylate (TEG). The essential advantages of these materials were the decrease of maximum temperature together with a decrease in the residual monomer content with respect to conventional cement formulations. The water absorption process obeyed diffusion laws and the equilibrium water content increased by the introduction of higher percentages of the hydrophilic component. This characteristic had an appreciable effect on the viscoelastic behavior analyzed by DMTA. These modified bone cements had reduced polymerization shrinkage and similar levels of porosity. Tensile test revealed that the introduction of TEGMA gave rise to an important modification of the mechanical behavior, with a noticeable increase in the fracture strain. This fact was also confirmed by means of the analysis of the fracture surfaces by SEM.

Absorption↗
PubMed1999

Influence of the modification of P/L ratio on a new formulation of acrylic bone cement.

The use of smaller powder/liquid (P/L) ratio favours the handling and wetting of poly(methyl methacrylate) (PMMA) beads in bone cement formulations. In this paper a P/L ratio of 1.86 is tested to overcome adhesion problems found in hydroxypropyl methacrylate (HPMA) modified bone cements and the influence on bone cement characteristics was analysed. The reduction of the P/L ratio leads to higher temperature peaks and shorter setting times, whereas the residual monomer content increases slightly. Water uptake obeys the diffusion laws, and the introduction of a more hydrophilic monomer gives rise to an increase of this parameter, which does not present significant changes with modification of the P/L ratio. Polymerization shrinkage is slightly greater because of the introduction of higher proportions of monomer in the formulation. Mechanical properties are similar to those obtained with conventional P/L ratios. The analysis of scanning electron microscopy (SEM) reveals an improvement of the adhesion between phases with respect to P/L = 2 formulations.

Acrylic Resins↗
PubMed1997

Application of tertiary amines with reduced toxicity to the curing process of acrylic bone cements.

4-Dimethylaminobenzyl alcohol (DMOH) and 4-dimethylaminobenzyl methacrylate (DMMO) were used as the activators in the benzoyl peroxide initiated redox polymerization for the preparation of acrylic bone cement based on poly(methylmethacrylate) beads of different particle size. The residual monomer content of the cured cements was about 2 wt %, independent of the redox system used in the polymerization, indicating that the activating effect of the tertiary aromatic amines DMOH or DMMO was sufficient to reach a polymerization conversion similar to that obtained with the benzoyl peroxide (BPO) N,N-dimethyl-4-toluidine (DMT) system. The BPO/DMOH and BPO/DMMO redox systems provided exotherms of decreasing peak temperature and increasing setting time, and the cured materials presented higher average molecular weight and similar glass transition temperatures in comparison with those obtained when DMT was used as the activator. In addition, these activators are three times less toxic than the classical DMT.

Acrylates↗
PubMed1997

Comparative study of four different pharmacokinetic computer programs: case study of a factor VIII preparation.

OBJECTIVE: To compare the pharmacokinetic parameters after a single dose of a monoclonally purified factor VIII concentrate in four different computer programs for pharmacokinetic analysis. SETTING: Haemophilia unit of a tertiary care university hospital. METHODS: Ten patients with severe haemophilia A were administered a single dose of 30-50 IU kg-1 body weight. Blood samples were drawn at different times during the first 48 h after infusion of factor VIII. Plasma factor VIII activity was measured by standard one-stage clotting assay and experimental data were analysed using four computer programs: JANA, PKCALC, F8SD and PCNONLIN. The pharmacokinetic models of analysis employed in the study were both compartmental and non-compartmental. The parameters compared were half-lives (t1/2) and mean residence time (MRT), volumes of distribution (V) and clearance (CL). Values obtained for each pharmacokinetic parameter in each program for the same model were tested for differences with a multiple analysis of variance (MANOVA). Linear correlation with the equivalent parameters for each program was also performed. RESULTS: Pharmacokinetic parameters differed depending on the computer program used to analyse the same data set. There were differences of statistical significance in t1/2 and V for one-compartment and two-compartment models derived by some of the programs, but none with the non-compartmental one. CL, considered model independent, showed differences between the programs evaluated. Correlations for each parameter generated were in general good (P < 0.05). CONCLUSION: Pharmacokinetic parameters differed depending on the computer program used to analyse the same data set. The same patient data used in different computer programs will result in significantly different parameter estimations, although the non-compartmental approach is less affected by variation, and this should be taken into consideration for comparative purposes, for the development of new preparations and for the implications in patient care and therapy monitoring.

Adolescent↗
PubMed1996

New aspects of the effect of size and size distribution on the setting parameters and mechanical properties of acrylic bone cements.

The effect of the size and the size distribution of poly(methyl methacrylate) (PMMA) beads on the classical kinetic parameters, peak temperature and setting time, for acrylic bone cement formulations prepared with PMMA particles in the range 10-60 microns of average diameter and a relatively wide size distribution is analysed. In addition, the combined effects of the concentration of the free radical initiator benzoyl peroxide and the activator N, N-dimethyl-4-toluidine for the different particle sizes are studied and compared with those commercially available formulations like CMW or Rostal. The results obtained indicated that the use of PMMA particles with average diameter of 50-60 microns, and a relatively wide size distribution (10-140 microns diameter), significantly changes the curing parameters (peak temperature and setting time) of the cement formulations in comparison with the classical behaviour of the commercial systems of CMW and Rostal, without any noticeable loss in the mechanical properties, such as tensile strength, elastic moduli, and compressive strength and plastic strain.

Benzoyl Peroxide↗
PubMed1996

Pharmacokinetics of conventional formulation versus fat emulsion formulation of amphotericin B in a group of patients with neutropenia.

The pharmacokinetics of amphotericin B administered in a conventional 5% dextrose (glucose) (5% D) solution and in a 20% fat emulsion formulation (Intralipid; 20% IL) were compared in 16 patients (mean age, 42 years [range, 18 to 70 years]) who had been hospitalized for hematological malignancies and with proven or suspected fungal infections. All of the patients received 50 mg (approximately 1 mg/kg of body weight per day) of amphotericin B daily in random order, either as a 50-ml lipid emulsion (20% IL) (group I) or in 500 ml of 5% D (group II). Five serum samples were taken during the 24 h after drug administration, and the levels of amphotericin B were measured by high-pressure liquid chromatography. Serum amphotericin B concentrations declined rapidly during the first 6 h, and subsequent measurements revealed a slow terminal elimination phase in both groups. The maximum serum amphotericin B concentration was significantly lower when the drug was administered in 20% IL (1.46 +/- 0.61 versus 2.83 +/- 1.17 micrograms/ml; P = 0.02). The area under the concentration-time curve from 0 to 24 h was also much lower in group I (17.22 +/- 11.15 versus 28.98 +/- 15.46 micrograms.h/ml). The half-life of the distribution phase was approximately three times longer in group I (2.92 +/- 2.34 h versus 0.64 +/- 0.24 h; P = 0.011). Conversely, the half-lives of the elimination phase were approximately equal in the two groups (11.44 +/- 5.18 versus 15.23 +/- 5.25 h). The mean residence times were also similar in both groups (19.41 +/- 11.13 versus 19.65 +/- 7.86 h). The clearance and the steady-state volume of distribution of amphotericin B in group I were about twice as great as those in group II (62.97 +/- 35.51 versus 33.01 +/- 14.33 ml/kg/h and 1,043.92 +/- 512.10 versus 562.32 +/- 152.05 ml/kg [P = 0.034], respectively). Finally, the volume of distribution in the central compartment was greater in group I than in group II (618.17 +/- 231.80 versus 328.19 +/- 151.71 ml/kg; P = 0.013), but there were no differences in the volume of distribution in the peripheral compartment (425.75 +/- 352.87 versus 234.14 +/- 75.92 ml/kg). These results suggest that amphotericin B has a different pharmacokinetic profile when it is administered in 20% IL than when it is administered in the standard 5% D form and that the main difference is due to a clear-cut difference in the steady-state volume of distribution, especially that in the central compartment.

Adolescent↗
PubMed1995

Administration of lipid-emulsion versus conventional amphotericin B in patients with neutropenia.

OBJECTIVE: To evaluate the usefulness of a 20% lipid emulsion as a delivery system for amphotericin B (1 mg/mL) administered over 1 hour to patients with neutropenia with hematologic malignancies compared with amphotericin B (0.1 mg/mL) administered in dextrose 5% solution over the same time. DESIGN: A prospective, comparative, randomized, labeled study. SETTING: Hematology unit, pharmacy service, university general hospital. PARTICIPANTS: Twenty patients with neutropenia with hematologic malignancies and proven or suspected fungal infections, 10 in the fat emulsion group (group 1) and 10 in the dextrose 5% group (group 2). MAIN OUTCOME MEASURES: Clinical tolerance (i.e., fever, shaking chills, nausea, blood pressure, pulse rate) and biologic tolerance (i.e., urea, creatinine, sodium, potassium). RESULTS: Clinical tolerance was comparable in both groups although amphotericin B in fat emulsion was better tolerated. Medication for symptoms related to the administration of amphotericin B was given in 6 cases in group 1 and in 8 cases in group 2. There was a statistically significant difference in the urea concentrations between the 2 groups (p = 0.023); there was an observed increase between the initial and the final serum urea (56.8 mg/d in group 1, 79.8 mg/dL in group 2). Statistically significant differences in creatinine serum concentrations (84.9 mumol/L in group 1, 123.8 mumol/L in group 2) (p = 0.047) were found. No differences were found in the antifungal efficacy of the treatment. However, as amphotericin B was started in the majority of cases (75%) as empiric treatment for fever unresponsive to antibiotic therapy, it is difficult to compare the efficacy of both preparations. CONCLUSIONS: The clinical tolerance of lipid-emulsion infusions is similar to that of conventionally administered amphotericin B therapy. Renal toxicity appears to be decreased when the drug is administered in a fat emulsion. This type of preparation permits the reduction of the volume and the time of administration for amphotericin B therapy.

Adolescent↗
PubMedDate not supplied

[Hematological changes and cerebrovascular disorders].

Stroke is due to abnormalities in the vascular wall, heart disease or hematological abnormalities. This last cause has a low causal rate in stroke but despite this its importance is self evident given that there still exists a number of stroke patients where etiology cannot be established. An exhaustive check was carried out on the different hematological phenomena which may play a part in the etiology of ischaemic or hemorrhagic strokes. We analyzed abnormalities in the red series, white series and blood cells; coagulapathies; discrasias of the plasmic cells and antiphospholipid antibodies. For each of the hematological entities, conceptual criteria, their role in brain hemorrhage or ischaemia, and therapeutic measures were established.

Antibodies, Antiphospholipid↗