Biomedical subjects

A Alonso

Publications and source records attributed to A Alonso.

At least 343 records · Page 19Linked to original sources

PubMed1992

Genetic polymorphism of human alpha 2 HS-glycoprotein (AHSG) in the resident population of the Basque Country (northern Spain).

The genetic polymorphism of human alpha 2 HS-glycoprotein (AHSG) was studied in a sample of 466 healthy unrelated individuals resident in the Basque Country (Northern Spain) by isoelectric focusing on micro-ultrathin polyacrylamide gels followed by immunoblotting. The allele frequencies obtained were AHSG*1 = 0.7253, AHSG*2 = 0.2683 and AHSG*3 = 0.0064. These allele frequencies were compared with those reported in other European populations.

Blood Proteins↗

PubMed1992

Cholinergic nucleus basalis neurons display the capacity for rhythmic bursting activity mediated by low-threshold calcium spikes.

Acetylcholine has long been known to play an important role in the cortical activation that accompanies the states of wakefulness and paradoxical sleep (for review, see Refs 17, 21) when this neurotransmitter is released from the cerebral cortex at the highest rates. The major supply of acetylcholine to the cerebral cortex arises from the cholinergic neurons of Meynert's Basal-ganglion or nucleus basalis of the forebrain. Lying in the substantia innominata within the major ascending pathway from the brain stem reticular formation, magnocellular basalis neurons project upon the cerebral cortex as the important ventral, extrathalamic relay of the ascending reticular activating system. Although the cholinergic basalis nucleus neurons have been shown to be important for cortical activation, the precise manner in which they influence cortical activity has not as yet been elucidated, in part because the cholinergic cells of this nucleus have not been identified in electrophysiological studies. Using intracellular recording in guinea-pig brain slices, we were able to record and fill with biocytin nucleus basalis neurons which were subsequently revealed by immunohistochemical staining to be choline acetyltransferase-positive and thus cholinergic. The cholinergic cells displayed rhythmic bursting activity mediated by a low-threshold calcium spike in vitro, which would endow them with a capacity for phasic (in addition to tonic) firing in vivo. By virtue of these different modes, cholinergic basalis neurons may accordingly deter or facilitate the cortical response to sensory input and may furthermore modulate the major frequencies of cortical activity across the different states of the sleep-waking cycle.

Animals↗

PubMed1992

Human chromosome 12 is required for optimal interactions between Tat and TAR of human immunodeficiency virus type 1 in rodent cells.

Levels of trans activation of the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR) by the virally encoded transactivator Tat show marked species-specific differences. For example, levels of transactivation observed in Chinese hamster ovary (CHO) rodent cells are 10-fold lower than those in human cells or in CHO cells that contain the human chromosome 12. Thus, the human chromosome 12 codes for a protein or proteins that are required for optimal Tat activity. Here, the function of these cellular proteins was analyzed by using a number of modified HIV-1 LTRs and Tats. Neither DNA-binding proteins that bind to the HIV-1 LTR nor proteins that interact with the activation domain of Tat could be implicated in this defect. However, since species-specific differences were no longer observed with hybrid proteins that contain the activation domain of Tat fused to heterologous RNA-binding proteins, optimal interactions between Tat and the trans-acting responsive RNA (TAR) must depend on this factor(s).

Animals↗

PubMed1992

Platelet kinetics in asthmatic patients with and without aspirin intolerance.

BACKGROUND: A reduced platelet survival time has been described in asthmatic patients. There is also good evidence that platelets are involved in aspirin induced asthma. Since aspirin intolerant patients usually suffer from an active disease and often require anti-inflammatory treatment, it has been suggested that platelet survival time may be shorter in aspirin intolerant asthmatic subjects than in aspirin tolerant subjects. The objective of this study was to investigate this hypothesis. METHODS: Thirteen asthmatic subjects (six aspirin tolerant and seven aspirin intolerant) in a stable clinical condition and ten healthy subjects were studied. Platelet kinetics and survival time were measured with indium-111 labelled autologous platelets. RESULTS: Mean (SD) platelet sequestration ratios in the spleen and liver were lower in asthmatic (2.3 (0.9) and 0.6 (0.2) respectively) than in healthy subjects (3.2 (0.7) and 1.1 (0.4) respectively). However, mean (SD) platelet survival time in asthmatic subjects (8 (2.7) days) did not differ from that in healthy subjects (7.6 (1.1) days). No differences were observed in platelet kinetics between aspirin tolerant and aspirin intolerant patients. CONCLUSIONS: These results suggest the existence of an active non-splenic pool of platelets in patients with asthma. However, they failed to show platelet kinetic differences among asthmatic subjects with and without aspirin intolerance and do not support previous studies suggesting an altered platelet survival in stable asthma.

Adult↗

PubMed1992

Effects of training on muscle O2 transport at VO2max.

To quantify the relative contributions of convective and peripheral diffusive components of O2 transport to the increase in leg O2 uptake (VO2leg) at maximum O2 uptake (VO2max) after 9 wk of endurance training, 12 sedentary subjects (age 21.8 +/- 3.4 yr, VO2max 36.9 +/- 5.9 ml.min-1.kg-1) were studied. VO2max, leg blood flow (Qleg), and arterial and femoral venous PO2, and thus VO2leg, were measured while the subjects breathed room air, 15% O2, and 12% O2. The sequence of the three inspirates was balanced. After training, VO2max and VO2leg increased at each inspired O2 concentration [FIO2; mean over the 3 FIO2 values 25.2 +/- 17.8 and 36.5 +/- 33% (SD), respectively]. Before training, VO2leg and mean capillary PO2 were linearly related through the origin during hypoxia but not during room air breathing, suggesting that, at 21% O2, VO2max was not limited by O2 supply. After training, VO2leg and mean capillary PO2 at each FIO2 fell along a straight line with zero intercept, just as in athletes (Roca et al. J. Appl. Physiol. 67: 291-299, 1989). Calculated muscle O2 diffusing capacity (DO2) rose 34% while Qleg increased 19%. The relatively greater rise in DO2 increased the DO2/Qleg, which led to 9.9% greater O2 extraction. By numerical analysis, the increase in Qleg alone (constant DO2) would have raised VO2leg by 35 ml/min (mean), but that of DO2 (constant Qleg) would have increased VO2leg by 85 ml/min, more than twice as much. The sum of these individual effects (120 ml/min) was less (P = 0.013) than the observed rise of 164 ml/min (mean). This synergism (explained by the increase in DO2/Qleg) seems to be an important contribution to increases in VO2max with training.

Adaptation, Physiological↗

PubMed1992

Electrophysiology of the mammillary complex in vitro. I. Tuberomammillary and lateral mammillary neurons.

1. The electrophysiological properties of the tuberomammillary and lateral mammillary neurons in the guinea pig mammillary body were studied using an in vitro brain slice preparation. 2. Tuberomammillary (n = 79) neurons were recorded mainly ventral to the lateral mammillary body as well as ventromedially to the fornix within the rostral part of the medial mammillary nucleus. Intracellular staining with horseradish peroxidase (n = 9) and Lucifer yellow (n = 3) revealed that these cells have several thick, long, spiny dendrites emerging from large (20-35 microns) fusiform somata. 3. Most tuberomammillary neurons (66%) fired spontaneously at a relatively low frequency (0.5-10 Hz) at the resting membrane potential. The action potentials were broad (2.3 ms) with a prominent Ca(2+)-dependent shoulder on the falling phase. Deep (17.8 mV), long-lasting spike afterhyperpolarizations were largely Ca(2+)-independent. 4. All tuberomammillary neurons recorded displayed pronounced delayed firing when the cells were activated from a potential negative to the resting level. The cells also displayed a delayed return to the baseline at the break of hyperpolarizing pulses applied from a membrane potential level close to firing threshold. Analysis of the voltage- and time dependence of this delayed rectification suggested the presence of a transient outward current similar to the A current (IA). These were not completely blocked by high concentrations of 4-aminopyridine, whereas the delayed onset of firing was always abolished when voltage-dependent Ca2+ conductances were blocked by superfusion with Cd2+. 5. Tuberomammillary neurons also displayed inward rectification in the hyperpolarizing and, primarily, depolarizing range. Block of voltage-gated Na(+)-dependent conductances with tetrodotoxin (TTX) selectively abolished inward rectification in the depolarizing range, indicating the presence of a persistent low-threshold sodium-dependent conductance (gNap). In fact, persistent TTX-sensitive, plateau potentials were always elicited following Ca2+ block with Cd2+ when K+ currents were reduced by superfusion with tetraethylammonium. 6. The gNap in tuberomammillary neurons may subserve the pacemaker current underlying the spontaneous firing of these cells. The large-amplitude spike afterhyperpolarization of these neurons sets the availability of the transient outward rectifier, which, in conjunction with the pacemaker current, establishes the rate at which membrane potential approaches spike threshold. 7. Repetitive firing elicited by direct depolarization enhanced the spike shoulder of tuberomammillary neurons. Spike trains were followed by a Ca(2+)-dependent, apamine-sensitive, slow afterhyperpolarization. 8. Lateral mammillary neurons were morphologically and electrophysiologically different from tuberomammillary neurons. All lateral mammillary neurons neurons recorded (n = 44) were silent at rest (-60 mV).(ABSTRACT TRUNCATED AT 400 WORDS)

4-Aminopyridine↗

PubMed1992

Electrophysiology of the mammillary complex in vitro. II. Medial mammillary neurons.

1. The electrophysiological properties of guinea pig medial mammillary body (MMB) neurons were studied using an in vitro slice preparation. 2. The neurons (n = 80) had an average resting potential of -57 +/- 5.5 (SD) mV, an input resistance of 176 +/- 83 M omega, and a spike amplitude of 58 +/- 15.7 mV. Most of the neurons were silent at rest (n = 52), but some fired spontaneous single spikes (n = 16) or spike bursts (n = 14). 3. The main electrophysiological characteristic of MMB neurons was the ability to generate Ca(2+)-dependent regenerative events, which resulted in very robust burst responses. However, this regenerative event was not the same for all neurons, ranging from typical low-threshold Ca2+ spikes (LTSs) to intermediate-threshold plateau potentials (ITPs). 4. The ITPs were distinct from the LTSs in that they lasted > or = 100 ms and were not inactivated at membrane potentials at or positive to -55 mV. 5. Some cells with a prominent ITP and no LTS (n = 36) displayed repetitive, usually rhythmic, bursting (n = 14). This ITP could be powerful enough to maintain rhythmic membrane potential oscillations after pharmacological block of Na+ conductances. 6. A group of 32 MMB neurons displayed complex bursting that was generated by activation of both LTSs and ITPs. This was established on the basis of their distinct time- and voltage-dependent characteristics. In a group of neurons (n = 14), the burst responses were exclusively generated by an LTS; however, a Ca(2+)-dependent plateau potential contributed to the generation of rebound-triggered oscillatory firing. 7. In addition to the Ca(2+)-dependent LTS and/or ITP, MMB neurons always displayed high-threshold Ca2+ spikes after reduction of K+ conductances with tetraethylammonium. 8. MMB neurons display one of the richer varieties of voltage-dependent Ca2+ conductances so far encountered in mammalian CNS. We propose that the very prominent endogenous bursting and oscillatory properties of MB neurons allow this nuclear complex to function as an oscillatory relay for the transmission of low-frequency rhythmic activities throughout the limbic circuit.

Animals↗

PubMed1992

Effects of sodium hyaluronate on tympanic membrane perforations.

The effects of topically applied 1% sodium hyaluronate as an alternative treatment to surgery for tympanic membrane perforations was studied. In an open study, the inclusion criteria were increased by accepting patients previously treated by surgery or with placebo and, compared with a previous study, the frequency at which sodium hyaluronate was applied was reduced. Reduction in the size of the perforation was detected in 12/16 (75.0%) patients, six (37.5%) of whom showed complete tympanic healing, and in the remaining four (25.0%) there was no healing. The average percentage reduction in the perforation area was 80.5%. The two factors altered in this trial, i.e. inclusion criteria and frequency of administration of treatment, had little influence on the degree of membrane healing.

Administration, Topical↗

PubMed1992

Foot-and-mouth disease virus typing by complement fixation and enzyme-linked immunosorbent assay using monovalent and polyvalent antisera.

An indirect "sandwich" enzyme-linked immunosorbent assay (ELISA) using polyvalent and monovalent antisera was compared with the 50% complement fixation (CF50) test for the detection of foot-and-mouth disease (FMD) O, A, and C virus types. ELISA was more sensitive than CF50 tests when polyvalent antisera were used for detecting the 3 types of virus in epithelial samples, whereas ELISA using monovalent antisera was the least sensitive technique. The ELISA performed with polyvalent antisera was 9 times more sensitive for detecting FMD virus than that with monovalent antisera. However, viral isolation in cell culture was the most sensitive detection system. The combined use of ELISA with polyvalent antisera and cell culture inoculations was the most effective procedure for identifying FMD virus in epithelial samples from the field.

Animals↗

PubMed1992

Transcription of BPV-1 genes in transfected F9 cells.

In F9 cells transformed with bovine papillomavirus type 1 (BPV-1) sequences two different phenotypes can be recognized. One cell type shows the characteristics of the parental stem cell line, whereas the other comprises cells with spindle-like morphology that do not adhere to each other, similar to retinoic acid-treated F9 embryonal carcinoma cells. The phenotypically altered cells plate more efficiently than the stem cells, grow well in soft agar and show an extended lifespan in the differentiated stage. Both types of cells contain BPV-1 DNA sequences as episomes, but only the non-stem-like cells have RNA transcripts for the unspliced E5 reading frame as well as for the spliced E6/E4.

Animals↗

PubMed1991

Phospholipase C activity-induced fusion of pure lipid model membranes. A freeze fracture study.

The structural effects of in situ production of diacylglycerol by phospholipase C in pure lipid model membranes have been examined by freeze fracture electron microscopy. Phospholipase C-activity induces massive aggregation and fusion of large unilamellar lipid vesicles and leads to the formation of a 'sealed' lipid aggregate; the outer membrane of this aggregate appears to be continuous. In some areas lipid arranges into a honeycomb structure; this structure is probably a precursor of a discontinuous inverted (type II) cubic phase. Similarly, enzyme treatment of multilamellar vesicles leads to extensive membrane fusion and vesiculation. Thus morphological evidence is obtained showing the ability of phospholipase C to induce bilayer destabilization and fusion. It is speculated that phospholipase C-induced membrane fusion involves a type II fusion intermediate induced by diacylglycerol produced locally.

Freeze Fracturing↗

PubMed1991

[Hypertensive encephalopathy: contribution of magnetic resonance].

We report a patient with hypertensive encephalopathy and we analyze his clinical and neurological imaging peculiarities. Computed tomography showed hypodense corticosubcortical lesions, whereas magnetic resonance scan disclosed extensive, wholly reversible enhanced signal lesions due to cerebral edema.

Brain Diseases↗

PubMed1991

Identification of human esterase D subunits from the homodimeric and heterodimeric forms of five phenotypes by a new two-dimensional isoelectric focusing method.

A new two-dimensional isoelectric focusing method was developed to identify the human esterase D (EsD) subunits from the homodimeric and heterodimeric forms of five EsD phenotypes. EsD polymorphism was also analyzed by one-dimensional isoelectric focusing under reducing and mild denaturing conditions to study the influence of dithiothreitol and low concentrations of urea on the focusing pattern of the EsD dimers.

Alleles↗

PubMed1991

In situ right gastroepiploic artery. A conduit for coronary revascularization.

The internal mammary artery is widely recognized as the graft of choice for coronary artery bypass grafting at present. Alternative conduits have been investigated in order to find other adequate long-term grafts. The right gastroepiploic artery has been recently used as a graft to bypass distal coronary vessels. From November 1989 to June 1990, we have implanted this artery in 46 cases. Pedicled grafts were implanted in 20 patients to the main right coronary artery, in 21 patients we grafted the right distal branches, in 3 patients the left anterior descending, and in 2 the circumflex branches. Mean grafts per patient were 3 in this series, with a mean of 2.2 arterial grafts per patient. One patient died in the early postoperative period. The remaining patients had an uncomplicated postoperative evolution. Thirteen patients underwent graft and coronary angiography. Direct or indirect graft patency was confirmed in all cases. The final important issue concerning the long-term patency of this graft will be solved in the future, but short-term patency rates of the right gastroepiploic artery can be anticipated when proper techniques are used.

Adult↗

PubMed1991

Adenoid cystic carcinoma of the infraspheno-temporal fossa. Latero-facial resection combined with multiple osteotomies.

Two cases of Adenoid Cystic Carcinoma (ACC) of the infrasphenotemporal fossa with invasion of the floor of the middle fossa are presented. Preoperative studies included CT-scan and cervical and cerebral angiography. The exposure and operative management comprised a latero-facial approach combined with multiple exposure osteotomies of the ascending mandibular ramus, orbitozygomatic region and a frontosphenotemporal craniotomy. This approach provides wide exposure of the posterolateral orbit, sphenoid wing and infratemporal and pterygomaxillary fossa. One of our patients died from massive recurrence in proximity to the cavernous sinus and the other is free of disease after 30 months.

Carcinoma, Adenoid Cystic↗

PubMed1991

Cavernomas of the central nervous system: clinical and neuroimaging manifestations in 47 patients.

Forty seven cases of central nervous system cavernous angioma (21 males and 26 females) are described. The main clinical signs were epilepsy and brainstem syndromes. Digital subtraction intra-arterial angiography, when used, failed to reveal cavernoma. CT detected many of the lesions, but the most successful supplementary diagnostic procedure was MRI which produces highly characteristic images of cavernous angioma. The diagnosis of cavernous angioma was confirmed in the 18 cases in which the tumour was removed surgically.

Adolescent↗

PubMed1991

Genetic polymorphism of alpha-2-HS-glycoprotein in a Spanish population.

The genetic polymorphism of alpha-2-HS-glycoprotein (AHSG) was analyzed in 489 unrelated individuals living in Madrid (central Spain), by isoelectric focusing in miniaturized polyacrylamide gels followed by immunoblotting. The allele frequencies were estimated to be 0.7147 and 0.2771 for AHSG*1 and AHSG*2, respectively. In addition to the common alleles, 3 rare variants (AHSG*3, AHSG*10 and AHSG*11) have been found in this study.

Alleles↗

PubMed1991

Development and evaluation of an enzyme-linked immunosorbent assay for detection, typing, and subtyping of vesicular stomatitis virus.

An indirect sandwich enzyme-linked immunosorbent assay (ELISA) has been used for vesicular stomatitis virus (VSV) typing using sets of monovalent and polyvalent rabbit/guinea pig antisera for identification of VSV types New Jersey (VNJ) and Indiana (VIND). The VIND polyvalent antiserum (VIND-P) detects any strain of the 3 subtypes of the VIND type (VIND-1, VIND-2, and VIND-3) with the same strong reactivity. It is also possible to subtype the VIND strains using VIND-P rabbit antiserum as capture antibody and monovalent VIND-1, VIND-2, or VIND-3 guinea pig antisera as detector. The ELISA proposed has about 10 times more sensitivity and provides 10% more positive results than does the complement fixation 50% (CF50) test when epithelial samples are tested.

Animals↗