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Biomedical subjects

F J Alvarez

Publications and source records attributed to F J Alvarez.

At least 19 recordsLinked to original sources
PubMed2006

Prick-test evaluation to anaesthetics in patients attending a general allergy clinic.

BACKGROUND AND OBJECTIVES: To analyse the prevalence of positive prick-tests to all medicaments normally checked in allergy units when a patient is suspected of being allergic to anaesthetics. To establish the degree of agreement between the antecedents of a previous history of an allergic reaction to a medicament and the positive result, or not, to the specific prick-test for the said medicament. METHODS: This was a prospective study, during 2003 and 2004, which analysed 473 patients referred by their doctors to allergy units to make retrospective diagnoses of an allergy to a drug. The prick-test was done using the undiluted drug. All patients were tested for 41 drugs. These include antibiotics, trimethoprim-sulphamethoxazole, non-steroidal anti-inflammatory drugs (NSAIDs) and perioperative drugs (PD): neuromuscular blocking drugs, latex, iodine, local anaesthetics, hypnotics, opioids and coadjuvants. Cohen's Kappa Index was used to determine the degree of agreement. RESULTS: 71.5% of patients studied presented a positive prick-test. The largest number of positive cases was found in antibiotics (56.4%), followed by PD (15.6%), NSAIDs (14.4%) and trimethoprim-sulphamethoxazole (12.7%). Among PD, the highest prevalence of positive prick-tests was found for neuromuscular blocking drugs (5.3%). Agreement between the substance suspected of causing the allergic reaction and the positive prick-test was excellent for penicillin (Kappa = 0.74) and other antibiotics (Kappa = 0.721) and good for NSAIDs (Kappa = 0.47) and iodine (Kappa = 0.54). CONCLUSIONS: The prevalence of patients with positive prick-tests to PD occurred in 15.6% in this prospective cohort. Neuromuscular blocking drugs were found to have the highest prevalence of positive prick-tests. There is positive agreement when the substance responsible for the allergic reaction is suspected, otherwise agreement is low.

Adult↗
PubMed2006

Demand for prior treatment in alcoholic patients.

The aim of this study is to analyze the use of health care resources by alcoholic patients. A prospective study of 176 patients (147 males, 29 females; mean age 42.9 years) diagnosed as alcohol dependent, according to criteria DSM-IV, has been carried out over one year (June 2002 to June 2003) in three centers of treatment for alcoholics in Castilla y León (Spain). Of the 176 patients, 67% had previously requested treatment for their alcoholism in other centers, mainly in mental-health (37.5%), emergency (34.1%), and primary care (31.8%). On average, they had requested treatment 2.27 times, the women more frequently than the men. The current study shows that alcohol-dependent patients frequently use health care services during the history of their dependence to treat their illness.

Adult↗
PubMed2005

Respiratory loading intensity and diaphragm oxidative stress: N-acetyl-cysteine effects.

We hypothesized that resistive breathing of moderate to high intensity might increase diaphragm oxidative stress, which could be partially attenuated by antioxidants. Our objective was to assess the levels of oxidative stress in the dog diaphragm after respiratory muscle training of a wide range of intensities and whether N-acetyl-cysteine (NAC) might act as an antioxidant. Twelve Beagle dogs were anesthetized with 1% propophol, tracheostomized, and subjected to continuous inspiratory resistive breathing (IRB) (2 h/day for 2 wk). They were further divided into two groups (n = 6): NAC group (oral NAC administration/24 h for 14 days) and control group (placebo). Diaphragm biopsies were obtained before (baseline biopsy) and after (contralateral hemidiaphragm) IRB and NAC vs. placebo treatment. Oxidative stress was evaluated in all diaphragm biopsies through determination of 3-nitrotyrosine immunoreactivity, protein carbonylation, hydroxynoneal protein adducts, Mn-SOD, and catalase, using immunoblotting and immunohistochemistry. Both protein tyrosine nitration and protein carbonylation were directly related to the amount of the respiratory loads, and NAC treatment abrogated this proportional rise in these two indexes of oxidative stress in response to increasing inspiratory loads. A post hoc analysis revealed that only the diaphragms of dogs subjected to high-intensity loads showed a significant increase in both protein tyrosine nitration and carbonylation, which were also significantly reduced by NAC treatment. These results suggest that high-intensity respiratory loading-induced oxidative stress may be neutralized by NAC treatment during IRB in the canine diaphragm.

Acetylcysteine↗
PubMed2005

Synaptic and subcellular localization of A-kinase anchoring protein 150 in rat hippocampal CA1 pyramidal cells: Co-localization with excitatory synaptic markers.

Excitatory and inhibitory ionotropic receptors are regulated by protein kinases and phosphatases, which are localized to specific subcellular locations by one of several anchoring proteins. One of these is the A-kinase anchoring protein (AKAP150), which confers spatial specificity to protein kinase A and protein phosphatase 2B in the rat brain. The distribution of AKAP150 was examined at rat hippocampal CA1 pyramidal cell asymmetric and symmetric post-synaptic densities and with respect to the distribution of markers of excitatory (vesicular glutamate transporter 1, glutamate receptor subunit 1) and inhibitory receptors (vesicular GABA transporter, GABA receptor type A beta2/3 subunits, gephyrin) and the Golgi marker, trans-Golgi network glycoprotein 38. AKAP150 was close to asymmetric synapses, consistent with numerous molecular and biochemical studies suggesting its interaction with components of the excitatory postsynaptic density. In contrast, we did not find AKAP150-immunoreactivity associated with inhibitory synapses in rat CA1 neurons, despite reports demonstrating an in vitro interaction between AKAP150 and GABA receptor type A receptor beta subunits, and the reported co-localization of these proteins in rat hippocampal cultures. There was some overlap between AKAP150 and GABA receptor type A receptor beta2/3-immunoreactivity intracellularly in perinuclear clusters. These findings support previous work indicating the integration of kinase and phosphatase activity at excitatory synapses by AKAP150, but do not support a role for selective targeting of AKAP150 and its accompanying proteins to inhibitory synapses.

A Kinase Anchor Proteins↗
PubMed2005

Magnetic resonance imaging findings in pre-clinical Creutzfeldt-Jakob disease.

The diagnosis of probable Creutzfeldt-Jakob disease (CJD) requires compatible clinical manifestations, typical electroencephalographical findings, and 14.3.3 protein positive in cerebrospinal fluid. Actually, MRI findings are not necessary, but they may support this diagnosis. The authors report a patient with definitive diagnosis of CJD who showed in a first MRI study performed two years before the clinical onset of the disease the same hyperintensities in caudate nuclei that were found in the last MRI. The authors think that these findings could be useful in detecting asymptomatic patients who need more extensive study and following.

Aged↗
PubMed2005

Expression of GABAB receptors in magnocellular neurosecretory cells of male, virgin female and lactating rats.

GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABA(B) receptors in magnocellular neurones in the SON and PVN. Robust GABA(B) receptor immunoreactivity (GABA(B)R; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABA(B)R immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABA(B)R immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABA(B)R was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABA(B)R immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABA(B) receptors in magnocellular neurosecretory cells.

Animals↗
PubMed2002

[Basic structure of respiratory and peripheral muscles in the beagle dog].

BACKGROUND: The dog is one of the most widely used animals in studies of respiratory physiopathology, mainly because of its physiological characteristics. However, ethical and legal constraints are placed on the use of some species in our context. OBJECTIVE: We studied the underlying structural features of respiratory and peripheral muscles in the beagle dog in order to suggest reference values for future studies. METHOD: Fourteen young beagles were selected. Samples were taken from the costal diaphragm (DFG), external intercostal (EI) and vastus medialis (VM) muscles. We analyzed fiber percentages and sizes (immunohistochemistry, using myosin heavy chain [MyHC (monoclonal antibodies), percentages and absolute number of MyHC isoforms (electrophoresis and ELISA), and level of membrane damage (immunohistochemistry, using anti-fibronectin monoclonal antibodies). RESULTS: In the EI muscle, type I fibers were larger (by 20%) than type II fibers. Fibers resistant to fatigue (type I) predominated greatly over fast contraction fibers (type II) in all three muscles analyzed (DFG 57% 11% vs. 45% 12%; EI 58% 5% vs. 43% 5%; and VM 70% 8% vs. 34% 7 %). Few hybrid fibers (co-expression of fast and slow MyHC) were found and their percentages were similar in all three muscles. The absolute expression of MyHC was greater in the VM than in the respiratory muscles, with a relative predominance of the MyHC I isoform in the DFG and VM muscles and a similar tendency in the EI muscle. Membrane damage was very slight in all three muscles. CONCLUSIONS: The phenotype characteristics of respiratory and peripheral muscles in the beagle correspond to what we would expect functionally for a breed initially selected for hunting, with minimal lesions under normal circumstances, a predominance of fibers and proteins that are resistant to fatigue, and larger fibers in the EI, a muscle that plays a role in respiration in dogs.

Animals↗
PubMed2002

Procion orange tracer dye technique vs. identification of intrafibrillar fibronectin in the assessment of sarcolemmal damage.

BACKGROUND: The use of Procion orange dye (POD) is one of the most widely accepted techniques to assess sarcolemmal damage. This phenomenon has been related to functional adaptation in skeletal muscles. The POD method includes intravenous injection of this colorant in vivo, enabling its identification inside those fibres with membrane leaks (fluorescence). However, the safety of the use of POD has not been proven. AIM: This study was designed to compare POD with a safer alternative, involving the identification of intracellular fibronectin using specific antibodies. METHOD: Eight Swiss mice were submitted to electrical stimulation of the lower limbs at different frequencies (10-80 Hz). Subsequently, the POD solution was infused, and samples from the vastus medialis muscle were obtained 24 h later. Samples were processed and serial sections were analysed using immunohistochemistry (monoclonal antibodies against fibronectin) and epifluorescence microscopy. RESULTS: Ninety-eight per cent of the fibres were equally classified by both techniques, which in addition showed good correlation (percentages of damaged fibres, r = 0.998, P < 0.001) and concordance (R1 = 0.82) in quantitative terms. CONCLUSIONS: Although the two techniques compared here are based on different principles, both are comparable in assessing sarcolemmal damage. This would facilitate comparisons between human and experimental studies. In addition, the fibronectin technique appears to be a suitable alternative for long-term studies including repeated biopsies.

Animals↗
PubMed2001

Illicit drugs and fitness to drive: assessment in Spanish Medical Driving Test Centres.

This study investigated the incidence of problems related to illicit drugs and fitness to drive among 8043 Spanish drivers assessed in 25 Medical Driving Test Centres at national level. In accordance with Spanish and European Union legislation, driving licences cannot be issued or renewed to people suffering from illicit drug-related problems. A small percentage (0.3%; n=24) of drivers interviewed had problems relating to drug use (abuse, dependence and induced disorders) and half of them (n=12) were also diagnosed as having problems with alcohol. Drivers with illicit drug-related problems were more often involved in road accidents and committed more traffic infractions during the last year (33.3%, n=8, and 79.2%, n=19, respectively) than those without problems related to illegal drug taking (12.3%, n=986, and 9.3%, n=748, respectively). Of drivers with drug problems 70.8% (n=17) were considered fit to drive. The results show that the incidence of drug-related problems is rare among Spanish drivers, and that in three out of four cases drivers with drug-related problems were considered fit to drive.

Accidents, Traffic↗
PubMed2001

Application of sorption--desorption moisture transfer modeling to the study of chemical stability of a moisture sensitive drug product in different packaging configurations.

The sorption--desorption moisture transfer (SDMT) model was used to predict the effect of desiccant quantity, tablet quantity and tablet initial moisture content on the relative humidity inside high density polyethylene (HDPE) bottles containing a moisture sensitive drug product, roxifiban tablets. The effect of these variables on the stability of roxifiban tablets in the HDPE bottles was also evaluated. There was a good correlation between the calculated relative humidity values inside the package and stability results. Tablet degradant concentration increased with the increase in the relative humidity calculated by the SDMT model. Desiccant quantity was the most important factor in controlling degradation rate, which decreased as the quantity of desiccant in the bottle was increased. For a given desiccant quantity, degradation rate increased with an increase in the weight of tablets in the bottle. The inclusion of a desiccant in the package significantly reduced the effect of initial tablet moisture content on stability. Nevertheless, the effect of initial moisture content was still discernible. This study demonstrated the practical utility of the SDMT model in understanding the correlation between packaging variables and the stability of a moisture sensitive product.

Adsorption↗
PubMed2001

Immunolocalization of the Na(+)-K(+)-2Cl(-) cotransporter in peripheral nervous tissue of vertebrates.

Efflux of Cl(-) through GABA(A)-gated anion channels depolarizes the cell bodies and intraspinal terminals of sensory neurons, and contributes to the generation of presynaptic inhibition in the spinal cord. Active accumulation of Cl(-) inside sensory neurons occurs through an Na(+)-K(+)-2Cl(-) cotransport system that generates and maintains the electrochemical gradient for this outward Cl(-) current. We studied the immunolocalization of the Na(+)-K(+)-2Cl(-) cotransporter protein using a monoclonal antibody (T4) against a conserved epitope in the C-terminus of the molecule. Western blots of frog, rat and cat dorsal root ganglion membranes revealed a single band of cotransporter immunoreactivity at approximately 160kDa, consistent with the molecular mass of the glycosylated protein. Deglycosylation with N-glycosidase F reduced the molecular mass to approximately 135kDa, in agreement with the size of the core polypeptide. Indirect immunofluorescence revealed strong cotransporter immunoreactivity in all types of dorsal root ganglion cell bodies in frog, rat and cat. The subcellular distribution of cotransporter immunoreactivity was different amongst species. Membrane labeling was more apparent in frog and rat dorsal root ganglion cell bodies than in cat. In contrast, cytoplasmic labeling was intense in cat and weak in frog, being intermediate in the rat. Cotransporter immunoreactivity also occurred in satellite cells, particularly in rat and cat dorsal root ganglia. The membrane region and axoplasm of sensory fibers were heavily labeled in cat and rat and less in frog. Three-dimensional reconstruction of confocal optical sections and dual immunolocalization with S-100 protein showed that the cotransporter immunoreactivity was prominently expressed in the nodal and paranodal regions of the Schwann cells. Ultrastructural immunolocalization confirmed the presence of immunoreactivity on the membranes of the axon and the Schwann cell in both the nodal region and the paranode. Treatment with sodium dodecylsulfate and beta-mercaptoethanol also uncovered intense cotransporter immunoreactivity in Schmidt-Lanterman incisures at the light microscopic level. The localization of the Na(+)-K(+)-2Cl(-) cotransporter protein is consistent with its function as a Cl(-)-accumulating mechanism in sensory neurons. Its distinctive presence in Schwann cells suggests that it could also be involved in K(+) uptake from the extracellular space, particularly in the paranodal region of myelinated axons, thereby regulating the extracellular ionic environment and the excitability of axons.

Action Potentials↗
PubMed2001

Differential in vitro and in vivo behavior of mouse ascorbate/Fe3+ and diamide oxidized erythrocytes.

Chemical oxidation of mouse erythrocytes has been carried out using two different oxidizing systems namely: Diamide and Ascorbate/Fe3+ together with different concentrations of the oxidant. These oxidation treatments produced different extents of modification in membrane proteins as was observed by electrophoretic analyses that showed a possible formation of high molecular weight aggregates. Lipid peroxidation was also observed as the result of these chemical treatments. The action of these two oxidation treatments produced different extents of lipid peroxidation in which the effect Ascorbate/Fe3+ reached higher values than that shown by diamide treatments. To study the resulting in vitro behavior of such oxidized erythrocytes, we have evaluated the recognition of oxidized erythrocytes by peritoneal macrophages. In the conditions used, diamide oxidized erythrocytes were more highly recognized by macrophages than Ascorbate/Fe3+ treated erythrocytes. However, in both cases an influence of serum factors in the recognition process can be inferred. Additionally, we have correlated on one side the action of different oxidation systems on mouse erythrocytes with different in vivo behavior and organ uptake of the oxidized erythrocytes. On the other side, differential targeting of oxidized erythrocytes to a liver or spleen was observed on dependence of the oxidant used.

Animals↗
PubMed2001

In vitro phagocytosis of carrier mouse red blood cells is increased by Band 3 cross-linking or diamide treatment.

Chemical alteration of red blood cells (RBCs) can induce increased phagocytosis of modified cells by macrophages. In this study we have used different chemical treatments for the modification of the mouse red-blood-cell membrane surface, namely oxidant compounds, such as ascorbate/Fe(+2) and diamide [azodicarboxylic acid bis(dimethylamide)], or Band 3-cross-linking reagents. We monitored the phagocytosis of oxidized or Band 3-cross-linked mouse red blood cells by peritoneal macrophages. The extent of phagocytosis of RBCs is not affected by oxidation with ascorbate/Fe(3+), but it is increased (up to 10%) by oxidation with 2 mM diamide. Furthermore, phagocytosis is greatly increased (up to 40%) as a result of cross-linking with either of two Band 3 bifunctional reagents [bis(sulphosuccinimidyl) suberate (BS(3)) and 3,3'-dithiobis(sulphosuccinimidyl propionate) (DTSSP)]. To evaluate targeting towards macrophages of such modified RBCs for therapeutical purposes, we have determined the phagocytosis of Band 3 carrier RBCs loaded with carbonic anhydrase. In this case phagocytosis is high enough (25%) to deliver the enzyme into macrophages. We have also assayed the influence of serum components and IgG on the efficiency of phagocytosis and discuss the possible phagocytosis mechanisms. In the case of BS(3)-cross-linked carrier RBCs, phagocytosis is markedly enhanced (from 12% up to 25%) by serum components. This opens a way for therapeutic application of these carrier RBCs, with special relevance in short-term delivery to cells of the mononuclear phagocytic system.

Animals↗
PubMed2001

Development of a time-cycled volume-controlled pressure-limited respirator and lung mechanics system for total liquid ventilation.

Total liquid ventilation can support gas exchange in animal models of lung injury. Clinical application awaits further technical improvements and performance verification. Our aim was to develop a liquid ventilator, able to deliver accurate tidal volumes, and a computerized system for measuring lung mechanics. The computer-assisted, piston-driven respirator controlled ventilatory parameters that were displayed and modified on a real-time basis. Pressure and temperature transducers along with a lineal displacement controller provided the necessary signals to calculate lung mechanics. Ten newborn lambs (<6 days old) with respiratory failure induced by lung lavage, were monitored using the system. Electromechanical, hydraulic, and data acquisition/analysis components of the ventilator were developed and tested in animals with respiratory failure. All pulmonary signals were collected synchronized in time, displayed in real-time, and archived on digital media. The total mean error (due to transducers, analog-to-digital conversion, amplifiers, etc.) was less than 5% compared with calibrated signals. Components (tubing, pistons, etc.) in contact with exchange fluids were developed so that they could be readily switched, a feature that will be important in clinical settings. Improvements in gas exchange and lung mechanics were observed during liquid ventilation, without impairment of cardiovascular profiles. The total liquid ventilator maintained accurate control of tidal volumes and the sequencing of inspiration/expiration. The computerized system demonstrated its ability to monitor in vivo lung mechanics, providing valuable data for early decision making.

Analysis of Variance↗
PubMed2001

Liquid ventilation: from experimental use to clinical application.

Despite advances in perinatal care of preterm infants, complications of prematurity are still common. If new conventional ventilatory interventions fail, ECMO is the only alternative method, but is a complex, invasive and costly technique and difficult to apply to small infants. Perfluorocarbon liquid ventilation is a promising technique. It has been demonstrated to be effective in experimental models, in mature and immature animals. However, its role in the management of human neonates, infants, older children and adults with acute respiratory failure is still not established. Both liquid ventilation strategies, total and partial, are able not only to maintain gas exchange, but also to reduce inflammatory changes. While total liquid ventilation remains as an experimental technique, partial liquid ventilation could be readily applied, but its implementation in clinical practice awaits results from ongoing and future clinical trials that may define its effectiveness.

Fluorocarbons↗
PubMed2001

Bilateral diaphragmatic paralysis after open heart surgery.

The purpose of the present case report is to present a case of bilateral diaphragmatic paralysis as a complication of open-heart surgery. A 47-year-old male was operated for aortic and mitral valve replacement. After discontinuation of sedation, bilateral diaphragmatic paralysis as well as motor and sensitive dysfunction in the four extremities was observed. The patient remained with mechanical ventilation support for twenty months. Two years after the operation a complete normalisation of the diaphragmatic motion was observed. Although uncommon, bilateral diaphragmatic paralysis after open-heart surgery could take place, being necessary long term mechanical ventilation support until recovery.

Aortic Valve↗