Biomedical subjects

M Rabadán

Publications and source records attributed to M Rabadán.

15 recordsLinked to original sources

PubMed2006

Frequency of the VO2max plateau phenomenon in world-class cyclists.

We aimed to determine the frequency of the VO2max plateau phenomenon in top-level male professional road cyclists (n = 38; VO2max [mean +/- SD]: 73.5 +/- 5.5 ml.kg(-1).min(-1)) and in healthy, sedentary male controls (n = 37; VO2max: 42.7 +/- 5.6 ml.kg(-1).min(-1)). All subjects performed a continuous incremental cycle-ergometer test of 1-min workloads until exhaustion. Power output was increased from a starting value of 25 W (cyclists) or 20 W (controls) at the rate of 25 W.min(-1) (cyclists) or 20 W.min(-1) (controls) until volitional exhaustion. We measured gas-exchange and heart rate (HR) throughout the test. Blood concentrations of lactate (BLa) were measured at end-exercise in both groups. We defined maximal exercise exertion as the attainment of a respiratory exchange rate (RER) >or= 1.1; HR > 95 % age-predicted maximum; and BLa > 8 mmo.l(-1). The VO2max plateau phenomenon was defined as an increase in two or more consecutive 1-min mean VO2 values of less than 1.5 ml.kg(-1).min(-1). Most cyclists met our criteria for maximal exercise effort (RER > 1.1, 100 %; 95 % predicted maximal HR [HRmax], 82 %; BLa > 8 mmol.l(-1), 84 %). However, the proportion of cyclists attaining a V.O (2max) plateau was considerably lower, i.e., 47 %. The majority of controls met the criteria for maximal exercise effort (RER > 1.1, 100 %; predicted HRmax, 68 %; BLa > 8 mmol. l(-1), 73 %), but the proportion of these subjects with a VO2max plateau was only 24 % (significantly lower proportion than in cyclists [p < 0.05]). Scientists should consider 1) if typical criteria of attainment of maximal effort are sufficiently stringent, especially in elite endurance athletes; and 2) whether those humans exhibiting the VO2max plateau phenomenon are those who perform an absolute maximum effort or there are additional distinctive features associated with this phenomenon.

Adult↗

PubMed2006

ACTN3 genotype in professional endurance cyclists.

The Z-disk protein alpha-actinin-3 is only expressed in type II muscle fibres, which are responsible for generating forceful contractions at high velocity. Despite the evolutionary conservation of alpha-actinin-3, approximately one in every five Caucasians of European ancestry is totally deficient in this protein, due to homozygosity for a R577X polymorphism in the ACTN3 gene. This, together with the results of recent research on elite athletes, suggests that the "null" XX polymorphism might confer some advantage to endurance performance events. To test this hypothesis, we studied the frequency distribution of R577X genotypes in a group of 50 top-level male professional cyclists (26.9 +/- 0.4 yrs [mean +/- SEM]; VO2max: 73.5 +/- 0.8 ml x kg (-1) x min (-1)). Their results were compared with those of a group of 52 Olympic-class male endurance runners (26.8 +/- 0.6 yrs; VO2max: 73.3 +/- 0.8 ml x kg (-1) x min (-1)) and 123 healthy, sedentary male controls. All subjects were Caucasian, and of European ancestry. No significant differences (p > 0.05) were found between groups: RR: 28.5 %; RX: 53.6 % and XX: 17.9 % in controls; RR: 28.0 %; RX: 46.0 % and XX: 26.0 % in cyclists; and RR: 25.0 %; RX: 57.7 %; XX: 17.3 % in runners). No differences were found in indices of endurance performance (VO2peak or ventilatory thresholds) between athlete carriers of each R577X genotype. In summary, although the alpha-actinin-3 deficient XX genotype may be detrimental for sprint performance in humans, the R577X polymorphism of the ACTN3 gene does not appear to confer an advantage on the ability of male athletes to sustain extreme endurance performance.

Actinin↗

PubMed2005

Ventricular septal defect in a world class runner.

We report the case of an elite male, East African endurance runner (18 years old) who ranked in the top 15 in the World Cross Country Championships (sub 21 year old category) despite having a ventricular septal defect (VSD; width: 0.22 cm) that was diagnosed 2 weeks after this event with echocardiographic evaluation. This athlete was a moderate altitude native ( approximately 3000 m). Cardiac dimensions were within normal limits and no significant pathological signs were observed. His Vo(2max) was relatively low given his performance level (67.9 ml kg(-1) min(-1)). Despite his limited training background (only 1 year), his running economy was, however, better than the values reported in our laboratory for Caucasian runners of the same age. Further cardiological follow up might confirm that the VSD causes no pathological effects or any performance detriment in future years.

Adolescent↗

PubMed2000

Invasive bladder cancer: a single-institution experience with bladder-sparing approach.

Our objective was to assess the efficacy and safety of a selective bladder-preserving approach by transurethral resection and sequential chemoradiotherapy in patients with muscle-invasive bladder cancer. From 1989 through 1997, 40 patients with biopsy-confirmed bladder cancer, clinical stages T2-4NxM0, were treated with induction by aggressive transurethral resection (TUR) and three cycles of methotrexate, cisplatin, and vinblastine (MCV) chemotherapy. Tumor response was evaluated by cystoscopy and biopsy. In complete responders, the treatment was continued by radiotherapy (60 Gy to the bladder and 50 Gy to pelvic lymph nodes). Radical cystectomy was recommended to patients with residual tumor. Clinical complete response rate to TUR and MCV chemotherapy was 70%. The 4-year actuarial overall survival rate for the whole series was 80.5%. Among 36 patients who completed chemotherapy and radiotherapy, the 4-year actuarial survival was 84%, with 82.6% surviving with their bladders intact. Freedom from local failure in complete responders to TUR-chemotherapy was 84%. Multivariate analysis revealed that the extent of initial TUR and status after TUR-chemotherapy were independent prognostic factors associated with survival and disease-free survival. This study confirms that the combination of aggressive TUR and sequential chemoradiotherapy with bladder preservation is an alternative treatment option to primary cystectomy for selected patients with invasive bladder carcinoma.

Aged↗

PubMed2000

[Guidelines of the Spanish Society of Cardiology for clinical practice in exercise testing].

Most exercise testing is performed in adults with known or suspected ischemic heart disease. In the last few years cardiac imaging techniques have been applied in this field, improving the information obtained with the procedure. However, the exceptions to this rule are emerging rapidly not only in healthy people (asymptomatic individuals, athletes, handicapped people) but also in cardiac patients (advanced congestive heart failure, hypertension, rhythm disorders, congenital heart disease, etc.). All the-se issues justify the need for a multidisciplinary consensus document in Spain. This paper reviews and updates the methodological aspects of the stress test, including those related to oxygen consumption measurements. The main aim of this review was to determine the role of exercise testing in the evaluation of ischemic heart disease as well as the applications of imaging stress testing. The usefulness of this test in other non-ischemic cardiac disorders and in selected subsets of healthy people is also reviewed.

Adult↗

PubMed1997

[Bladder neoplasms in patients under 40 years of age].

The incidence, presentation and clinical evolution of vesical tumours diagnosed in our Centre over the last 10 years (1986-1995) in patients under forty are examined. This retrospective study included 19 of the 643 neoplasias treated during that period; 7 of these in patients under 30 and 12 in patients over 31. Haematuria was the most frequent reason for visiting the Centre. At the time of diagnosis, all cases were surface tumours and none progressed to the infiltrant stage. Tumours in patients over 30 are characterised by a higher histological grade and greater relapse rate versus those in patients under 30. Therefore, age may be a favourable prognostic factor in patients under 30 versus the older group who follow a course more similar to the remainder of usual patients. Diagnosis and treatment of these neoplasias should be just the same as for tumours in older patients.

Adult↗

PubMed1995

Ageing and prostate: age-related changes in androgen receptors of epithelial cells from benign hypertrophic glands compared with cancer.

Total and nuclear androgen receptors (AR) were studied from epithelial cells in internal and external prostatic zones in 51- to 86-year-old individuals with benign prostatic hyperplasia (BPH) (n = 68) and prostatic cancer (n = 9). We focussed on the role played by androgens on those processes, despite the fact that at these ages, its secretion has normally decreased. In BPH, the nuclear AR do not change, but total measured androgen receptors rise with age (r = 0.5, P < 0.01). Total or nuclear AR do not correlate with gland volume, despite its increase with age (r = 0.8, P < 0.05). In prostates less than 180 cc in volume, there is a significant correlation between size, serum total testosterone level (r = 0.53, P < 0.05) and prostatic specific antigen (PSA) (r = 0.63, P < 0.05). The amount of nuclear AR in cells from the external zone (infiltrated by cancer or healthy) is two times greater than in those from the internal region. Total receptor content of the external zone cells is also high, but the sample is too small to demonstrate an age dependence. The results suggest that ageing is accompanied by an accumulation of non-nuclear AR in the cytosol, that does not play a role in the development of BPH because the amount of nuclear receptors remains unaltered. The enrichment in nuclear receptors of the external zone cells, independently of the presence of cancer, points to a greater androgen dependence in these cells than in cells of the internal region.

Aged↗

PubMed1995

[The index of PSA age vs PSA density. 2 new instruments in the detection of prostatic carcinoma].

A prospective study was designed to get to know the reliability of PSA density and PSA age index as tools in the diagnostic approach for prostate carcinoma. It was noted that PSA age index is more susceptible than PSA density to diagnose prostate cancer. We noted also that up to 80% of patients with prostate cancer and intermediate PSA levels have PSA density < 0.15 and that, according to current protocols biopsy should not have been performed. It was concluded that the value of PSA age index is at least equal to PSA density, but it eradicates the subjectivity introduced by this data because of the need of measuring prostate volume. We believe that in the future it may be indicated to perform biopsies at PSA levels above 4 ng/ml, and it may be necessary to decrease PSa normal density levels down to 0.1 or less.

Adult↗

PubMed1983