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Biomedical subjects

J Ibáñez

Publications and source records attributed to J Ibáñez.

At least 19 recordsLinked to original sources
PubMed2006

Flat and uphill climb time trial performance prediction in elite amateur cyclists.

The aim of this study was to determine physiological, anthropometric, biomechanical and hormonal variables related to road flat and uphill climb performance. Eighteen elite level amateur road cyclists (21.1 +/- 3.8 yrs), homogeneous with regard to time trial performance (coefficient of variation: 2.9-5.2 %), were measured for frontal area (FA), maximal strength, power, cross-sectional area of the quadriceps femoris muscle and basal serum concentrations of total testosterone (TT), free testosterone (FT) and cortisol (C). Maximal (W (max)) and submaximal workload were measured during a progressive discontinuous maximal cycling laboratory test, and two all-out time trial performance tests (duration range: 1049-1251 s) were also conducted outdoors on two separate days: a 14-km flat road (average gradient of 0.2 %) and a 6.7-km uphill climb (average gradient of 6 %). Significant negative correlations (p < 0.01-0.001) were observed between the individuals' 14-km flat time values and the individual values of W (max) (r = - 0.90) and FA (r = - 0.73). Regression analysis showed that the individual values of the 6.7-km uphill climb trial performance time correlated significantly (p < 0.05-0.001) with those of FT (r = - 0.75) and W (max) x kg (-1) (r = - 0.66). The present results suggest that flat time trial performance in highly elite amateur cyclists is mainly related to absolute maximal workload and anthropometric variables, whereas uphill climb time trial performance is associated with maximal workload normalized to body mass, as well as with an increased anabolic-androgenic activity.

Adult↗
PubMed2006

Effect of loading on unintentional lifting velocity declines during single sets of repetitions to failure during upper and lower extremity muscle actions.

The purpose of this study was to examine the effect of different loads on repetition speed during single sets of repetitions to failure in bench press and parallel squat. Thirty-six physical active men performed 1-repetition maximum in a bench press (1 RM (BP)) and half squat position (1 RM (HS)), and performed maximal power-output continuous repetition sets randomly every 10 days until failure with a submaximal load (60 %, 65 %, 70 %, and 75 % of 1RM, respectively) during bench press and parallel squat. Average velocity of each repetition was recorded by linking a rotary encoder to the end part of the bar. The values of 1 RM (BP) and 1 RM (HS) were 91 +/- 17 and 200 +/- 20 kg, respectively. The number of repetitions performed for a given percentage of 1RM was significantly higher (p < 0.001) in half squat than in bench press performance. Average repetition velocity decreased at a greater rate in bench press than in parallel squat. The significant reductions observed in the average repetition velocity (expressed as a percentage of the average velocity achieved during the initial repetition) were observed at higher percentage of the total number of repetitions performed in parallel squat (48 - 69 %) than in bench press (34 - 40 %) actions. The major finding in this study was that, for a given muscle action (bench press or parallel squat), the pattern of reduction in the relative average velocity achieved during each repetition and the relative number of repetitions performed was the same for all percentages of 1RM tested. However, relative average velocity decreased at a greater rate in bench press than in parallel squat performance. This would indicate that in bench press the significant reductions observed in the average repetition velocity occurred when the number of repetitions was over one third (34 %) of the total number of repetitions performed, whereas in parallel squat it was nearly one half (48 %). Conceptually, this would indicate that for a given exercise (bench press or squat) and percentage of maximal dynamic strength (1RM), the pattern of velocity decrease can be predicted over a set of repetitions, so that a minimum repetition threshold to ensure maximal speed performance is determined.

Adult↗
PubMed2006

Multiple origins of cultivated grapevine (Vitis vinifera L. ssp. sativa) based on chloroplast DNA polymorphisms.

The domestication of the Eurasian grape (Vitis vinifera ssp. sativa) from its wild ancestor (Vitis vinifera ssp. sylvestris) has long been claimed to have occurred in Transcaucasia where its greatest genetic diversity is found and where very early archaeological evidence, including grape pips and artefacts of a 'wine culture', have been excavated. Whether from Transcaucasia or the nearby Taurus or Zagros Mountains, it is hypothesized that this wine culture spread southwards and eventually westwards around the Mediterranean basin, together with the transplantation of cultivated grape cuttings. However, the existence of morphological differentiation between cultivars from eastern and western ends of the modern distribution of the Eurasian grape suggests the existence of different genetic contribution from local sylvestris populations or multilocal selection and domestication of sylvestris genotypes. To tackle this issue, we analysed chlorotype variation and distribution in 1201 samples of sylvestris and sativa genotypes from the whole area of the species' distribution and studied their genetic relationships. The results suggest the existence of at least two important origins for the cultivated germplasm, one in the Near East and another in the western Mediterranean region, the latter of which gave rise to many of the current Western European cultivars. Indeed, over 70% of the Iberian Peninsula cultivars display chlorotypes that are only compatible with their having derived from western sylvestris populations.

DNA, Chloroplast↗
PubMed2005

Differences in physical fitness and throwing velocity among elite and amateur male handball players.

This study compared physical characteristics (body height, body mass [BM], body fat [BF], and free fatty mass [FFM]), one repetition maximum bench-press (1RM (BP)), jumping explosive strength (VJ), handball throwing velocity, power-load relationship of the leg and arm extensor muscles, 5- and 15-m sprint running time, and running endurance in two handball male teams: elite team, one of the world's leading teams (EM, n = 15) and amateur team, playing in the Spanish National Second Division (AM, n = 15). EM had similar values in body height, BF, VJ, 5- and 15-m sprint running time and running endurance than AM. However, the EM group gave higher values in BM (95.2 +/- 13 kg vs. 82.4 +/- 10 kg, p < 0.05), FFM (81.7 +/- 9 kg vs. 72.4 +/- 7 kg, p < 0.05), 1RM (BP) (107 +/- 12 kg vs. 83 +/- 10 kg, p < 0.001), muscle power during bench-press (18 - 21 %, p < 0.05) and half squat (13 - 17 %), and throwing velocities at standing (23.8 +/- 1.9 m . s (-1) vs. 21.8 +/- 1.6 m . s (-1), p < 0.05) and 3-step running (25.3 +/- 2.2 m . s (-1) vs. 22.9 +/- 1.4 m . s (-1), p < 0.05) actions than the AM group. Significant correlations (r = 0.67 - 0.71, p < 0.05 - 0.01) were observed in EM and AM between individual values of velocity at 30 % of 1RM (BP) and individual values of ball velocity during a standing throw. Significant correlations were observed in EM, but not in AM, between the individual values of velocity during 3-step running throw and the individual values of velocity at 30 % of 1RM (BP) (r = 0.72, p < 0.05), as well as the individual values of power at 100 % of body mass during half-squat actions (r = 0.62, p < 0.05). The present results suggest that more muscular and powerful players are at an advantage in handball. The differences observed in free fatty mass could partly explain the differences observed between groups in absolute maximal strength and muscle power. In EM, higher efficiency in handball throwing velocity may be associated with both upper and lower extremity power output capabilities, whereas in AM this relationship may be different. Endurance capacity does not seem to represent a limitation for elite performance in handball.

Adult↗
PubMed2005

[Comparison of the effectiveness of pentobarbital and thiopental in patients with refractory intracranial hypertension. Preliminary report of 20 patients].

OBJECTIVE: To assess the effectiveness of pentobarbital and thiopental to control raised intracranial pressure (ICP), refractory to first level measures, in patients with severe traumatic brain injury. MATERIAL AND METHODS: Prospective, randomized study to compare the effectiveness between two treatments: pentobarbital and thiopental. The patients will be selected from those admitted to the Intensive Care Unit with a severe traumatic brain injury (postresuscitation Glasgow Coma Scale equal or less than 8 points) and raised ICP (ICP>20 mmHg) refractory to first level measures according to the Brain Trauma Foundation guidelines. The adverse effects of both treatments were also collected. RESULTS: We present the results of the first 20 patients included. Ten received pentobarbital and the other ten thiopental. There were no statistically significance differences in patients'characteristics (age, sex, severity of the trauma at admission and comorbilities). There were no differences between both groups neither in the Glasgow Coma Scale at admission (thiopental six points; pentobarbital seven points; P=0.26) nor in the admission Cranial Tomography, according to the Traumatic Coma Data Bank Classification. Thiopental treatment controlled raised ICP in five cases and pentobarbital in two cases (P=0.16). Five patients in the thiopental group died and eight in the pentobarbital group (P=0.16). There were no statistically differences between both groups regarding to the presence of hypotension (P=1) or infectious complications. CONCLUSIONS: These preliminary results indicate that thiopental could be more effective than pentobarbital in patients with refractory intracranial hypertension. These results support previous experimental findings that show that both treatments are not equal and justify to continue this study.

Adult↗
PubMed2005

[Variability in the surgical indications for posttraumatic intradural lesions].

INTRODUCTION: The surgical treatment of focal intradural lesions is still a matter of considerable debate. This is especially important in the decision to evacuate brain contusions. We present the results of a prospective observational study in which the main goal was to analyze intracenter variability in the indication for surgery in focal posttraumatic intradural lesions in a department of Neurosurgery of a University Hospital with a specialized neurotrauma unit. CLINICAL MATERIAL AND METHODS: Between May 1 and December 31, 2001, 32 patients with a closed traumatic brain injury and an intradural posttraumatic focal lesion were included. The patients studied were a subgroup included in the European multicenter observational study of the management of intradural lesions conducted under the aegis of the European Brain Injury Consortium (EBIC). RESULTS: Intradural lesions > 25 cc were immediately evacuated. Nine out of thirteen patients with lesions < 25 cc also underwent surgery due to intracranial hypertension or neuroworsening. In all patients in whom lesions were surgically evacuated, the postoperative CT-scan showed neuroradiological improvement of the signs of mass effect or midline shift. CONCLUSIONS: In our center, we found no evidence of significant variability in the indications for surgery in intradural lesions of more than 25 cc. However, significant differences were detected among neurosurgeons in the surgical indications for lesions below 25 cc. The small sample analyzed precludes generalization of these conclusions. The definitive results of the EBIC study will provide the neurosurgical community with a better understanding of variability in the management of these lesions.

Adolescent↗
PubMed2004

Development of a standard set of microsatellite reference alleles for identification of grape cultivars.

In order to investigate the comparability of microsatellite profiles obtained in different laboratories, ten partners in seven countries analyzed 46 grape cultivars at six loci (VVMD5, VVMD7, VVMD27, VVS2, VrZAG62, and VrZAG79). No effort was made to standardize equipment or protocols. Although some partners obtained very similar results, in other cases different absolute allele sizes and, sometimes, different relative allele sizes were obtained. A strategy for data comparison by means of reference to the alleles detected in well-known cultivars was proposed. For each marker, each allele was designated by a code based on the name of the reference cultivar carrying that allele. Thirty-three cultivars, representing from 13 to 23 alleles per marker, were chosen as references. After the raw data obtained by the different partners were coded, more than 97% of the data were in agreement. Minor discrepancies were attributed to errors, suboptimal amplification and visualization, and misscoring of heterozygous versus homozygous allele pairs. We have shown that coded microsatellite data produced in different laboratories with different protocols and conditions can be compared, and that it is suitable for the identification and SSR allele characterization of cultivars. It is proposed that the six markers employed here, already widely used, be adopted as a minimal standard marker set for future grapevine cultivar analyses, and that additional cultivars be characterized by means of the coded reference alleles presented here. The complete database is available at http://www.genres.de/eccdb/vitis/ Cuttings of the 33 reference cultivars are available on request from the Institut National de la Recherche Agronomique Vassal collection (didier.vares@ensam.inra.fr).

Alleles↗
PubMed2004

In-hospital and 2-year survival of patients treated with mechanical ventilation for acute exacerbation of COPD.

OBJECTIVE: To analyze in-hospital and 2-year survival of patients who require mechanical ventilation with intubation after acute respiratory failure due to exacerbation of chronic obstructive pulmonary disease (COPD). The secondary objective was to identify the prognostic factors for in-hospital mortality and mortality at 2 years. PATIENTS AND METHODS: We retrospectively studied 101 patients with suspected COPD admitted to the intensive care unit between July 1993 and December 1998. Variables potentially related to mortality were analyzed with a univariate model and by logistic regression. RESULTS: In-hospital survival was 74.3% and 2-year survival was 55.4%. Survival at 2 years was 81% for patients discharged from hospital. The variables associated with in-hospital mortality were age greater than 65 years, electrocardiographic diagnosis of chronic cor pulmonale, and development of multiorgan dysfunction syndrome. No factors predictive of mortality at 2 years were identified. CONCLUSIONS: The in-hospital survival rate for patients with an acute exacerbation of COPD who require mechanical ventilation is good and the 2-year survival rate is acceptable. Age, electrocardiographic signs of cor pulmonale, and development of multiorgan dysfunction syndrome were associated with greater risk of in-hospital mortality.

Acute Disease↗
PubMed2003

Strength training effects on physical performance and serum hormones in young soccer players.

To determine the effects of simultaneous explosive strength and soccer training in young men, 8 experimental (S) and 11 control (C) players, aged 17.2 (0.6) years, were tested before and after an 11-week training period with respect to the load-vertical jumping curve [loads of 0-70 kg (counter-movement jump CMJ0-70)], 5- and 15-m sprint performances, submaximal running endurance and basal serum concentrations of testosterone, free testosterone and cortisol. In the S group, the 11-week training resulted in significant increases in the low-force portion of the load-vertical jumping curve (5-14% in CMJ0-30, P<0.01) and in resting serum total testosterone concentrations (7.5%, P<0.05), whereas no changes were observed in sprint running performance, blood lactate during submaximal running, resting serum cortisol and resting serum free testosterone concentrations. In the C group, no changes were observed during the experimental period. In the S group, the changes in CMJ0 correlated ( P<0.05-0.01) with the changes in the 5-m ( r=0.86) and 15-m ( r=0.92) sprints, whereas the changes in CMJ40 correlated negatively with the changes in the testosterone:cortisol ratio ( r=-0.84, -0.92, respectively, P<0.05). These data indicate that young trained soccer players with low initial strength levels can increase explosive strength by adding low-frequency, low-intensity explosive-type strength training. The inverse correlations observed between changes in CMJ40 and changes in the testosterone:cortisol ratio suggest that a transient drop in this ratio below 45% cannot always be interpreted as a sign of overstrain or neuroendocrine dysfunction.

Adaptation, Physiological↗
PubMed2003

Magnetotunneling spectroscopy of dilute Ga(AsN) quantum wells.

We use magnetotunneling spectroscopy to explore the admixing of the extended GaAs conduction band states with the localized N-impurity states in dilute GaAs(1-y)N(y) quantum wells. In our resonant tunneling diodes, electrons can tunnel into the N-induced E- and E+ subbands in a GaAs(1-y)N(y) quantum well layer, leading to resonant peaks in the current-voltage characteristics. By varying the magnetic field applied perpendicular to the current direction, we can tune an electron to tunnel into a given k state of the well; since the applied voltage tunes the energy, we can map out the form of the energy-momentum dispersion curves of E- and E+. The data reveal that for a small N content (approximately 0.1%) the E- and E+ subbands are highly nonparabolic and that the heavy effective mass E+ states have a significant Gamma-conduction band character even at k=0.

Journal Article↗
PubMed2003

[Intraoperative detection of ischemic brain hypoxia using oxygen tissue pressure microprobes].

OBJECTIVE AND IMPORTANCE: Detection of intraoperative ischemic events could lead to the resolution of their cause and to the prevention of the definitive establishment of a postoperative infarct. We want to illustrate the possibilities that intraoperative monitoring of oxygen tissue pressure (PtiO2) in critical areas during a neurosurgical vascular procedure offers, enhancing its reliability and immediacy in obtaining information about tissue oxygenation status as a marker of ischemia in the vascular territory at risk. CLINICAL PRESENTATION: We report the case of a 32 year-old male with a deep arteriovenous malformation (AVM) localised in the insular region. The patient had been previously treated with radiosurgery without achieving a satisfactory result. INTERVENTION: AVM removal was performed through a transylvian transinsular approach. PtiO2 was monitorised at the temporal pole (reference area) and at the posterior temporal region (risk area). Both probes maintained close tissue oxygenation levels until the last stage of the AVM resection when, during the coagulation of a supposed afferent vessel, a brisk fall of the oxygen tissue pressure in the posterior temporal region was detected. An ischemic infarct in this area was observed postoperatively. CONCLUSIONS: PtiO2 monitoring has a high reliability in the detection of intraoperative tissue hypoxia. Data obtained could lead to early identification of these events and, whatever possible, to resolve this situation preventing the definitive establishment of an ischemic infarct.

Adult↗
PubMed2001

Increased blood ammonia in hypoxia during exercise in humans.

The effect of acute hypoxia on blood concentration of ammonia ([NH3]b) and lactate (la-]b) was studied during incremental exercise(IE), and two-step constant workload exercises (CE). Fourteen endurance-trained subjects performed incremental exercise on a cycle ergometer under normoxic (21% O2) and hypoxic (10.4% O2) conditions. Eight endurance-trained subjects performed two-step constant workload exercise at sea level and at a simulated altitude of 5000 m (hypobaric chamber, P(B)=405 Torr; P(O2)=85 Torr) in random order. In normoxia, the first step lasted 25 minutes at an intensity of 85 % of the individual ventilatory anaerobic threshold (AT(vent), ind) at sea level. This reduced workload was followed by a second step of 5 minutes at 115% of their AT(vent), ind. This test was repeated into a hypobaric chamber, at a simulated altitude of 5,000 m. The first step in hypoxia was at an intensity of 65 % of AT(vent), ind., whereas workload for the second step at simulated altitude was the same as that of the first workload in normoxia (85 % of AT(vent), ind). During IE, [NH3]b and [la-]b were significantly higher in hypoxia than in normoxia. Increases in these metabolites were highly correlated in each condition. The onset of [NH3]b and [la-]b accumulation occurred at different exercise intensity in normoxia (181W for lactate and 222W for ammonia) and hypoxia (100W for lactate and 140W for ammonia). In both conditions, during CE, [NH3]b showed a significant increase during each of the two steps, whereas [la-]b increased to a steady-state in the initial step, followed by a sharp increase above 4 mM x L(-1) during the second. Although exercise intensity was much lower in hypoxia than in normoxia, [NH3]b was always higher at simulated altitude. Thus, for the same workload, [NH3]b in hypoxia was significantly higher (p<0.05) than in normoxia. Our data suggest that there is a close relationship between [NH3]b and [la-]b in normoxia and hypoxia during graded intensity exercises. The accumulation of ammonia in blood is independent of that of lactate during constant intense exercise. Hypoxia increases the concentration of ammonia in blood during exercise.

Adult↗
PubMed2001

[Minor head injury management in Spain: a multicenter national survey].

INTRODUCTION AND OBJECTIVES: Despite of the high incidence of minor head injury, there is still controversy and disparity of criteria regarding its management. The lack of consensual protocols and clinical guidelines can lead to deficiencies in the attention to these patients and to inadequate use of resources. The objective of this study has been to describe the present situation of the management of this entity in the neurosurgical departments of the Spanish public hospitals, and to compare it with other European countries. MATERIAL AND METHODS: A 57-item questionnaire regarding different aspects of minor head injury was designed and distributed to the 66 neurosurgical departments of the Spanish National Health System between December 1999 and February 2000. RESULTS: A 83.3% of responses were obtained. More than 92,000 patients per year are assisted at the Spanish third-level hospitals (general hospitals) after suffering a minor head injury. In-hospital on duty neurosurgeons are not available in 49.1% of the Spanish neurosurgical departments. Only in 7.3% of the centres the neurosurgeon is the first physician that assists these patients. However, in 52.7% of the hospitals neurosurgical evaluation is required if the patient refers transient loss of consciousness. A GCS score of 13 is still included in the group of minor head injuries in 29.1% of the centres. Although 89.1% of the surveyed neurosurgical departments considered as satisfactory the attention they provide to these patients, 85.5% think that it would be convenient to elaborate clinical guidelines. Cranial x-ray is considered a useful diagnostic tool by only 38.2% of the centres, however, 89.1% of them still use it as a routine. CT-scan is systematically indicated in all patients after suffering a mild head trauma only in 5.5% of the centres, although it is completely available in 74.5% of them. The study of economical costs shows that choosing cranial CT as screening tool in these patients would mean a 40.6% reduction in costs compared to a management based on x-ray plus in-hospital observation. CONCLUSIONS: This study shows the inter-hospital variability of minor head injury management in Spain. Clinical guidelines are considered as positive and necessary. Although the Spanish situation is similar to that in other European countries, following the tendency toward a broader cranial CT utilisation, would improve diagnosis profitability and economical efficiency. The results of this study may contribute to the creation of consensual protocols and clinical guidelines in our country that help in daily practice decision-making optimising assistance quality.

Adult↗
PubMed2001

[The use of moderate hypothermia in the treatment of patients with severe craniocerebral trauma].

Traumatic brain injury initiates several metabolic processes that can increase the primary injury. It is well established that in severe head injuries, posttraumatic secondary insults, such as brain hypoxia, hypotension or anemia, exacerbate neuronal injury and lead to a poorer outcome. Experimental and clinical evidence suggests that moderate hypothermia (32-34 degrees C), may limit some of these deleterious secondary metabolic responses. Recent laboratory studies and prospective controlled clinical trials of induced moderate hypothermia for relatively short periods (24-48 h) in patients with severe head injury, have demonstrated good intracranial pressure control and better outcome when compared with patients maintained in normothermia and given conventional treatment. Despite its proven clinical role in neuroprotection, hypothermia research has been inconstantly followed for various reasons. In this paper we review the mechanisms of neuroprotection in hypothermia, the different preclinical and clinical studies that favor its use as a neuroprotector in severe head injury or in patients in whom high intracranial pressure is refractory to first tier measures. The evidence that favors hypothermia is discussed. We also discuss the negative results of the still unpublished multicentre trial on prophylactic moderate hypothermia developed in the USA. The main problem with moderate hypothermia is the lack of a systematic methodology to induce and maintain it. Also, optimal duration of its use and the methodology and timing for rewarming have not been determined. Consequently, the results of different trials are difficult to analyze and compare. However, most evidence suggests that hypothermia provides remarkable protection against the adverse effects of neuronal damage that is exacerbated by secondary injury. Further prospective controlled trials with clearly defined methodology are needed before this method is implemented in daily clinical practice. The most important task for the years to come may be to focus on refining this procedure, defining the optimal time of cooling and rewarming and to optimize the methods of rapidly inducing and maintaining low temperature. It is also essential to define the most appropriate method and velocity of the rewarming phase, in which many successfully controlled patients deteriorate and die.

Brain Injuries↗
PubMed2001

Neuropsychological and psychiatric complications in endoscopic third ventriculostomy: a clinical case report.

The clinical case report of a patient who underwent an endoscopic third ventriculostomy for the treatment of a slit ventricle syndrome is presented. After surgery the patient developed a severe complication consisting of an organic personality disorder, characterised by impulsiveness, physical heteroaggressiveness, binge eating, hypersomnia and impairment of memory, and frontal-executive functions.A frontal lobe lesion may explain some of the symptoms presented, such as the uncontrolled impulses, the aggressive behaviour, and even the binge eating. However, a longitudinal neuropsychological evaluation showed a severe deficit in immediate memory and difficulties in planning and consolidation of newly learned information, which may be best related to damage in the frontal basal structures of the brain: the fornix and its connection to the hippocampus and the mamillary bodies. Postoperative MR images confirmed the clinical hypothesis. The emergence of such a severe organic personality disorder and cognitive disturbances as a psychiatric complication of an endoscopic third ventriculostomy has not, it seems, been previously reported elsewhere. Clinicians should take these possible complications into account when recommending this so-called minimally invasive neuroendoscopic procedure.

Adult↗
PubMed2000

Factors influencing surgical complications of intra-axial brain tumours.

OBJECT: Extensive surgical resection remains nowadays the best treatment available for most intra-axial brain tumours. However, postoperative sequelae can outweigh the potential benefits of surgery. The goal of this study has been to review the results of this treatment in our Department in order to quantify morbidity and mortality and determine predictive risk factors for each patient. METHOD: We report a retrospective study of 200 patients submitted to a craniotomy for intra-axial brain tumours including gliomas and metastases. Postoperative major complications are analysed and related to different variables. An exhaustive review of the literature concerning the main controversial points about primary and metastatic brain tumours surgery is done. FINDINGS: The overall major complication rate was 27.5%, with neurological complications being the most frequently encountered. We did not find a statistically significant relation between them and the grade of eloquence of the tumoural area. Infratentorial tumour location, previous radiotherapy and reoperations were factors strongly related to the incidence of regional complications. Age over 60 and severe concomitant disease were risk factors for systemic complications. INTERPRETATION: The results from published series concerning surgical complications after craniotomies for brain tumours are not comparable because of the lack of homogeneity between them. The knowledge of the complications rate in each particular neurosurgical department turns out essentially to provide the patient with tailored information about risks before surgery.

Adolescent↗
PubMed2000

Intermittent hypobaric hypoxia induces altitude acclimation and improves the lactate threshold.

The physiological responses to short-term intermittent exposure to hypoxia in a hypobaric chamber were evaluated. The exposure to hypoxia was compatible with normal daily activity. The ability of the hypoxia program to induce hematological and ventilatory adaptations leading to altitude acclimation and to improve physical performance capacity was tested. Six members of a high-altitude expedition were exposed to intermittent hypoxia and low-intensity exercise (in cycle-ergometer) in the INEFC-UB hypobaric chamber over 17 d, 3-5 h x d(-1), at simulated altitude of 4,000 m to 5,500 m. Following this hypoxia exposure program, significant increases were found in packed cell volume (41 to 44.6%; p<0.05), red blood cells count (4.607 to 4.968 10(6) cells x microL(-1); p<0.05), and hemoglobin concentration (14.8 to 16.4 g x dL(-1); p<0.05), thus implying an increase in the blood oxygen transport capacity. Significant differences in exercise blood lactate kinetics and heart rate were also observed. The lactate vs. exercise load curve shifted to the right and heart rate decreased, thus indicating an improvement of aerobic endurance. These results were associated with a significant increase in the ventilatory anaerobic threshold (p<0.05). Significant increases (p<0.05) in pulmonary ventilation, tidal volume, respiratory frequency, O2 uptake, CO2 output and ventilatory equivalents to oxygen (VE/Vo2) and carbon dioxide (VE/co2) were observed at the ventilatory threshold and within the transitional zone of the curves. We conclude that short-term intermittent exposure to moderate hypoxia, in combination with low-intensity exercise in a hypobaric chamber, is sufficient to improve aerobic capacity and to induce altitude acclimation.

Acclimatization↗