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Biomedical subjects

G S Roi

Publications and source records attributed to G S Roi.

16 recordsLinked to original sources
PubMed2000

Pepsinogens: physiology, pharmacology pathophysiology and exercise.

Human gastric mucosa contains aspartic proteinases that can be separated electrophoretically on the basis of their physical properties into two major groups: Pepsinogen I (PGA, PGI); and Pepsinogen II (PGC, PGII). Pepsinogens consist of a single polypeptide chain with molecular weight of approximately 42,000 Da. Pepsinogens are mainly synthesized and secreted by the gastric chief cells of the human stomach before being converted into the proteolytic enzyme pepsin, which is crucial for the digestive processes in the stomach. Pepsinogen synthesis and secretion are regulated by positive and negative feed-back mechanisms. In the resting state pepsinogens are stored in granules, which inhibit further synthesis. After appropriate physiological or external chemical stimuli, pepsinogens are secreted in the stomach lumen where hydrochloric acid, secreted by the parietal cells, converts them into the corresponding active enzyme pepsins. The stimulus-secreting coupling mechanisms of pepsinogens appear to include at least two major pathways: one involving cAMP as a mediator, the other involving modification of intracellular Ca(2+)concentration. Physiological or external chemical stimuli acting through the intracellular metabolic adenyl cyclase are more effective in inducing ' de novo ' pepsinogen synthesis than those acting through intracellular Ca(2+). The activation of protein kinase C (PK-C) would appear to be involved in regulatory processes. The measurement of pepsinogens A and C in the serum is considered to be one of the non-invasive biochemical markers for monitoring peptic secretion and obtaining information on the gastric mucosa status of healthy subjects. Recently, pepsinogen measurements have been used as an effective biochemical method for evaluating and monitoring patients with gastrointestinal diseases and for checking the effects of drug treatment. The level of PGA in the serum is always high in normal gastritis, while in atrophic gastritis it is always low. In both cases the PGC level in the serum is high. In most gastrointestinal pathologies the ratio between the PGA/PGC decreases. Various reports concerning hormone and/or enzyme modification as well as gastrointestinal distress in the case of long distance exercise have been reported. It has been suggested that the origin of the gastrointestinal distress experienced by long distance runners is a transient ischaemia of the gastric mucosa; it is also suggested that a hypobaric-hypoxic environment could contribute to induce gastric mucosa necrosis. Interrelation between gastrointestinal distress, hypobaric-hypoxic environment and modifications of PGA and PGC, gastrin and cortisol was evaluated in 13 athletes after a marathon performed at 4300 m. Gastrointestinal symptoms occurred in approximately 40% of the athletes. After the race the athletes showed a significant increase of gastrin and cortisol, while the ratio between PGA/PGC decreased. No relationship was observed between gastrointestinal symptoms and hormonal changes after the race. A control group of five subjects, who had been exposed to the same environmental conditions, showed no gastrointestinal or hormonal alteration. Conversely, control subjects presented a significant decrease of cortisol related to the circadian rhythm. The same incidence of gastrointestinal symptoms at high altitude and at sea level and the absence of pathological alteration of PGA and PGC in the serum of the athletes indicates that running a marathon and living for 6 days at 4300 m does not induce gastric mucosa necrosis. Cortisol and gastrin alteration observed in the athletes at this altitude would seem to be related to an activation of the mesopontine and forebrain structures involved in the behavioural and metabolic integration of the autonomic control and arousal and psychophysical-exercise stress. 2000 Academic Press@p$hr

Altitude Sickness↗
PubMed1999

Marathons in altitude.

PURPOSE: We examined the effect of altitude up to 5200 m on marathon (42,195 m) performances. METHODS: Eight elite and four good runners participated in a marathon at 4300-m altitude (A1), and five elite runners participated both in A1 and in a marathon at 5200-m altitude (A2). The maximal aerobic power (VO2max) was determined indirectly in altitude during A1 and A2 expeditions from the scores of a 12-min running test. The fractions of VO2max utilized during both races were calculated from the linear relationship between running speed and VO2 described by Costill and Fox (1969). RESULTS: VO2max significantly decreases with altitude (P<0.001). We found a linear relationship (R2 = 0.73, P<0.001) between the speed of each participant in the sea level marathon and the speed of A1. The mean difference between the sea level and the A1 speed was 35+/-9% (P<0.001). In A1, elite runners utilized 63+/-8% whereas good runners utilized 52+/-8% of VO2max (P<0.001). The five elite runners utilized 74+/-6%; 67+/-1% (P< 0.01), and 71+/-3% (P<0.01) of their VO2max at sea level, A1, and A2, respectively. In Al, the mean heart rate (HR) was higher in elite than in good runners (P<0.001), whereas the percentage of maximum theoretical HR was 83+/-3% and 81+/-5%, respectively (P>0.05). CONCLUSIONS: Marathon performance in altitude is mainly affected by the lower VO2max. The better performance of elite marathoners in altitude compared with good runners was related to the higher % of VO2max maintained during every marathon. The differences between the expected and the observed performances at high altitude depend on the uneven running path and on a poorer economy of running that is related to the higher mechanical work of breathing. The fractional utilization of VO2max seems lowered by acute exposure to altitude and slightly increases with acclimatization.

Adult↗
PubMed1996

Pepsinogens and gastrointestinal symptoms in mountain marathon runners.

Although there are various descriptive reports concerning exercise-induced gastrointestinal distress, the role of gastrointestinal hormones and/or enzymes is not definitively established. In this study we investigated the behaviour of pepsinogens (PGI and PGII) after an endurance race performed at an altitude of 4,300 m by 13 well-trained marathon runners, with the aim to establish their interrelationship with gastrointestinal distress and with the modifications of gastrin and cortisol. The athletes showed a significant rise in gastrin (p < 0.01) and in cortisol (p < 0.01) and a significant decrease in PGI (p < 0.01) and PGII (p < 0.05) after the race. The PGI/PGII ratio presented small variations indicating that heavy exercise has less effects on PGs than those observed for gastrin. Gastrointestinal symptoms occurred in 6 athletes (46%) during the race and in 8 athletes (62%) after the race. No relationship was found between gastrointestinal symptoms and hormonal modifications after the race. A control group of 5 subjects was used: they (n = 5) did not show any significant modification of gastrin and PGs during the period spent at the above altitude, indicating that travel, altitude and acclimatization, food and beverages, do not influence the behaviour of these hormones. Conversely, they presented a significant decrease of cortisol (p < 0.05) linked to the circadian rhythm. The data of the present study indicate that the potential damage of gastrointestinal apparatus in mountain marathon runners is not related to the above mentioned hormones.

Adult↗
PubMed1995

Platelet indices in athletes performing a race in altitude environment.

Physical activity could modify platelet count and platelet indices. Previous reports showed modifications after exercise linked to type and duration of sports performances. The shortage of studies in this field stems from the crucial methodological problem of EDTA (ethylenediaminetetraacetic acid)-dependent, mean platelet volume modifications: the published data on platelets count and indices were obtained by using a light-scattering system without standardization of the period elapsed from drawing to measurement. We present a study of platelet indices performed in athletes participating in an "extreme" performance, a race of 30 km in altitude (6,700 m of ascents and descents), using standardized measurement by an aperture-impedance instrument transferred in the field. The platelet count and mean platelet volume significantly increased in athletes, whereas platelet distribution width decreased. The mean initial values were 240.6*10(9)/L for platelet count, 8.79 fL for mean platelet volume, and 15.79% for platelet distribution width. The correspondent mean final values were 288.4*10(9)/L, 9.14 fL, and 15.48%. The modifications of platelet count and indices were always in the physiological reference range. The entity and the rapidity of platelet count and indices modifications suggest that the more probable source of variation is the recruitment of noncirculating pools of mature platelets. Strenuous exercise does not show abnormal changes of platelet parameters.

Adolescent↗
PubMed1994

Seasonal fluctuations of selected physiological characteristics of elite alpine skiers.

The effects of heavy resistance training and jumping exercise were examined during the 1989-1990 season in 12 international level alpine skiers. The athletes were tested before, during, immediately after training and during the period off training (June, July, October 1989, April 1990). Their mechanical behaviour was investigated using firstly squat jumps performed without (SJ) or with low extra loads (20 kg, SJ20kg) and high extra loads (equivalent to body mass on the shoulders, SJbm) and secondly 15-30 s continuous jumping. These tests allowed the assessment of explosive dynamic strength production (SJ and SJ20kg), slow dynamic strength (SJbm) and maximal mechanical power (continuous jumping). The training adopted resulted in specific changes in neuromuscular performance; in fact all the variables studied showed a significant improvement (P < 0.01) from the beginning compared to the end of training. The range of improvement was between 55.4% (SJbm) and 12.5% (average power during 15-s continuous jumping). The enhancement of SJ had become significant by July. Surprisingly, even when no strength or jumping training was performed during the competition period (November-April), no deterioration in the neuromuscular performance was observed, there being no significant difference between the test values obtained in October 1989 and April 1990. It was concluded that the demanding competition programme of alpine skiers may provide a training stimulus adequate to maintain the neuromuscular improvement induced by training throughout the competition season.

Adult↗
PubMed1994

Aspirin does not affect exercise performance.

A single-blind, cross-over study was carried out to evaluate the effects of acetylsalicylic acid (ASA) on cardiorespiratory performance during exercise. Eighteen young men, 9 athletes and 9 untrained but active subjects, performed a progressive maximal exercise test on a cycle ergometer (30 watt, 3 min steps, starting at 60 watt) on three different occasions, after a single administration of plain aspirin (1000mg of ASA), chewable buffered aspirin (1000mg of ASA and 600 mg of calcium carbonate) and placebo. Continuous measurement of breath-by-breath ventilation, oxygen consumption, carbon dioxide output, respiratory frequency and heart rate was carried-out at rest and during the exercise test. Blood lactate concentration was measured just before the start of exercise and at the third minute of each step in order to detect the anaerobic threshold. The pharmacokinetics of aspirin during exercise was also investigated in ten of the eighteen participants. The analysis of all investigated variables did not show any statistically significant difference between treatments, suggesting that a single dose of 1000mg of aspirin does not affect physical performance during submaximal and maximal exercise.

Adolescent↗
PubMed1994

Maximal isometric force and muscle cross-sectional area of the forearm in fencers.

The maximal isometric force (MIF) of a muscle is directly related to its cross-sectional area (CSA). Strength training produces an increase in muscular force while muscular hypertrophy becomes appreciable at a later time; in asymmetric sports, training causes significant increases in force and muscular mass of the dominant limb of the athlete. The aim of this study was to analyse the differences in muscular force and trophism between the dominant and non-dominant forearms in fencers and in controls. The data of 17 male distance runners (age 21.4 +/- 2.4 years, body mass 74.0 +/- 5.0 kg, height 180 +/- 6 cm) were compared with those of 58 male fencers (age 23.0 +/- 6.7 years, body mass 71.9 +/- 9.3 kg, height 178 +/- 7 cm) drawn from the ranking lists of the National Fencing Committee. They trained for a mean of 11.4 +/- 6.0 (range 2-36) years, commencing at 10.7 +/- 4.5 years of age. Cross-sectional area (muscle plus bone) was estimated in the dominant and non-dominant forearm using a simplified anthropometric method. Maximal isometric force was determined using a mechanical handgrip dynamometer. The differences in CSA and isometric force between the two limbs and between fencers and controls were tested using paired and unpaired Student's t-tests, respectively. Significant differences in CSA and maximal force were observed between the dominant and non-dominant forearm in fencers (both P < 0.001) and in controls (P < 0.005 and P < 0.001, respectively). The fencers showed a greater CSA (P < 0.001) and force (P < 0.001) in the dominant forearm compared with the control group. Furthermore, the differences between the dominant and non-dominant limb of the fencers were significantly greater than the differences between the dominant and non-dominant limb of the controls (P < 0.001 for CSA and P < 0.05 for force). No significant differences in stress ratio (force/CSA) were obtained in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Cortisol, testosterone, and free testosterone in athletes performing a marathon at 4,000 m altitude.

Cortisol, testosterone, free testosterone and the ratio between free testosterone and cortisol (FTCR) were monitored in six athletes participating in a marathon starting at 3,860 and finishing at 3,400 m, having reached the top at 5,100 m altitude. Blood was drawn at sea level before the departure for the mountain area, after a week of acclimatization, immediately after the marathon and after a 24-hour recovery period from the run. Cortisol increased after acclimatization and especially after the marathon; it decreased to normal values after recovery. Testosterone decreased after acclimatization, especially after the run; it presented a partial recovery 24 h after the race. Free testosterone did not decrease after acclimatization and presented partial recovery. FTCR could also be useful for monitoring fitness, overtraining and overstrain in strenuous and ultraendurance exercise.

Adult↗
PubMed1994

Growth hormone and insulin-like growth factor I in athletes performing a marathon at 4000 m of altitude.

Human growth hormone (hGH) characteristically increases during physical exercise. In sports medicine, hGH changes have mostly been described in short-term performances under standardized laboratory procedures. We studied hGH and insulin-like growth factor I (IGF-I) under field conditions in 7 runners performing a marathon at 4000 m of altitude, to study the hormonal changes under extreme endurance effort and to evaluate the release of 22 kDa and 20 kDa monomers under these conditions, in comparison with a control group. The blood samples were taken at sea level, after 1 week of acclimatization, immediately after the run, and after a recovery of 24 h from the marathon. hGH was quantified by using a polyclonal method, a 22 kDa specific monoclonal method and a monoclonal method recognizing both 22 kDa and 20 kDa isoforms. A significant increase in hGH was noted using all methods after the marathon, followed by a significant decrease after recovery. Significant differences between athletes and controls were found only for the measurement after the marathon. No statistically reliable decrease of IGF-I was observed in athletes and controls. We obtained more limited hGH rises than previously described in athletes; the importance of lactate levels indicates that the use of physical exercise as a stimulation test for hGH should be closely standardized. The 20 kDa monomer and other hGH molecular forms played a limited role in the hormone increase: in our experience, elevation of hGH in heavy exercise corresponds mostly to the 22 kDa isoform. We suggest that the evaluation of hGH elevation in sports medicine could be accurately performed using specific 22 kDa monoclonal assays.

Adult↗
PubMed1993

Usefulness of free testosterone/cortisol ratio during a season of elite speed skating athletes.

Free testosterone/cortisol ratio (FTCR) was used in eight elite speed skaters (five males, three females), during an eight-month season, to study the effectiveness of the hormonal parameter as a marker of the condition of overstrain and/or incomplete recovery. We did not find values lower than 0.35 x 10(-3). We confirmed the reliability of the criterion of FTCR decrease of 30% or more to indicate temporary incomplete recovery from intensive training and residual weariness and, consequently, of reduced effectiveness for competitive purposes; a formula was used in this case to calculate FTCR. When FTCR was calculated by using directly measured FT, we remarked that such threshold criterion could not be used and the significant decrease was of 18% or more. The major problem of FTCR is the limitation of its use to male athletes, although the trend found in females was similar to that presented in males. FTCR is a useful index in elite speed skaters: broader application of this index and further investigation are required to set testing times, to use direct measurement of free testosterone and, finally, to find an equivalent support for women.

Adult↗
PubMed1990

Partial rupture of the pectoralis major muscle in athletes.

Partial rupture of the pectoralis major muscle is quite a rare event in sports traumatology and information about its treatment is lacking in literature. In this paper the long term effect of conservative non-surgical treatment in two body-builders and one shot-putter is discussed, who reported the partial rupture while performing bench lifts with barbells. Functional recovery was evaluated a few years after the injury (from 4 to 7) with an isokinetic dynamometer (Cybex II, Lumex INC N.Y.), measuring maximal shoulder adduction-abduction torques at different angular speeds (60, 180, and 300 degrees/s). The results were compared with those of five healthy athletes practicing either body-building or weight-lifting. From the present study we conclude the following: the non-invasive treatment of a partial rupture of the pectoralis major muscle may produce almost complete functional recovery; in normal subjects adduction muscles are advantageous in comparison to the abduction ones.

Athletic Injuries↗
PubMed1989

Changes in force, cross-sectional area and neural activation during strength training and detraining of the human quadriceps.

Four male subjects aged 23-34 years were studied during 60 days of unilateral strength training and 40 days of detraining. Training was carried out four times a week and consisted of six series of ten maximal isokinetic knee extensions at an angular velocity of 2.09 rad.s-1. At the start and at every 20th day of training and detraining, isometric maximal voluntary contraction (MVC), integrated electromyographic activity (iEMG) and quadriceps muscle cross-sectional area (CSA) assessed at seven fractions of femur length (Lf), by nuclear magnetic resonance imaging, were measured on both trained (T) and untrained (UT) legs. Isokinetic torques at 30 degrees before full knee extension were measured before and at the end of training at: 0, 1.05, 2.09, 3.14, 4.19, 5.24 rad.s-1. After 60 days T leg CSA had increased by 8.5% +/- 1.4% (mean +/- SEM, n = 4, p less than 0.001), iEMG by 42.4% +/- 16.5% (p less than 0.01) and MVC by 20.8% +/- 5.4% (p less than 0.01). Changes during detraining had a similar time course to those of training. No changes in UT leg CSA were observed while iEMG and MVC increased by 24.8% +/- 10% (N.S.) and 8.7% +/- 4.3% (N.S.), respectively. The increase in quadriceps muscle CSA was maximal at 2/10 Lf (12.0% +/- 1.5%, p less than 0.01) and minimal, proximally to the knee, at 8/10 Lf (3.5% +/- 1.2%, N.S.). Preferential hypertrophy of the vastus medialis and intermedius muscles compared to those of the rectus femoris and lateralis muscles was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Functional assessment of high level ice-dancing.

In these studies the anthropometric characteristics and some functional characteristics of ice-dancers are analysed. It has been shown that the maximum oxygen uptake is similar to that of classical ballet dancers. Tests effected on the ice revealed a high production of lactate, the involvement of the anaerobic metabolism, and high heart rates. It is concluded that the high production of lactate during the free dance on ice is due to the isometric muscular contraction, necessary to maintain certain positions.

Adolescent↗
PubMed1989

[Muscle weakness and intolerance to exercise in mitochondrial myopathies].

Muscle weakness and intolerance to exercise are two of the main features commonly shown by patients affected by mitochondrial myopathies. In order to obtain an objective and quantitative evaluation of muscle weakness and endurance, we studied an evaluation protocol devoted to the assessment of 1) muscle strength by the isokinetic ergometer and 2) the metabolic aspects of exercise by means of Maximal Oxygen Consumption and endurance by a Steady State Submaximal exercise evaluation. The protocol has been applied to the study of patients affected by mitochondrial diseases and proved to be a reliable method to quantitate the defect in the oxidation pathways, either before or during the therapeutic follow-up.

Humans↗
PubMed1988

Force of knee extensor and flexor muscles and cross-sectional area determined by nuclear magnetic resonance imaging.

The maximal strengths of knee extensor (E) and flexor (F) muscles were compared in a group of 6 male subjects aged 24-31 years. Cross-sectional area (CSA) of E and F was evaluated from planimetric measurements of Nuclear Magnetic Resonance (NMR) imaging axial scans, carried out at five levels along the thigh. Maximal CSA for E was found at 2/3 upper femur height and at 1/3 lower femur height for F. Maximum isometric force (MIF) of E was found to be 135% greater than that of F. The maximum CSA of E was found to be 93% larger than CSA of F. The calculated mechanical advantage of the flexors was estimated to be 13.8% higher than that of the knee extensors (0.116 +/- 0.012 and 0.132 +/- 0.005, respectively). However, when MIF of E and F were standardised for their respective CSA, no significant difference was found between their stress: 80.1 +/- 15.5 N.cm-2 for E and 70.5 +/- 7.0 N.cm-2 for F. From the present study, it is concluded that no significant difference exists between the maximum stress of knee extensor and flexor muscles despite large differences in their absolute values of force and CSA and that the NMR imaging technique enables accurate in-vivo determination of the CSA of individual muscles.

Adult↗