Biomedical subjects

H M Alessio

Publications and source records attributed to H M Alessio.

13 recordsLinked to original sources

PubMed2000

Generation of reactive oxygen species after exhaustive aerobic and isometric exercise.

UNLABELLED: Many studies have implicated elevated oxygen consumption (VO2) associated with aerobic exercise as contributing to oxidative stress. Only a few studies have investigated nonaerobic exercise and its relation to pro-oxidant and antioxidant activities. PURPOSE: The purpose of this study was to compare biomarkers of oxidative stress: lipid peroxidation, protein oxidation, and total antioxidants in blood after exhaustive aerobic (AE) and nonaerobic isometric exercise (IE). METHODS: Blood samples were collected from 12 subjects who performed a maximum AE and IE test and were analyzed for thiobarbituric acid (TBARS), carbonyls, lipid hydroperoxides (LH), and oxygen radical absorbance capacity (ORAC). RESULTS: VO2 increased 14-fold with AE compared with 2-fold with IE. Protein carbonyls increased 67% (P < 0.05) pre- to immediately and 1 h post-AE, and 12% pre- to immediately post-IE and returned to baseline 1 h post-IE. TBARS did not increase significantly with either treatment. LH increased 36% above rest during IE compared with 24% during AE (P < 0.05). ORAC increased 25% (P < 0.05) pre- to post-AE, compared with 9% (P < 0.05) pre- to post-IE. CONCLUSION: There was evidence of oxidative stress after both exhaustive aerobic and isometric exercise. Lipid hydroperoxides, protein carbonyls, and total antioxidants increased after both IE and AE. Due to the different metabolic demands of aerobic and isometric exercise, we can rule out a mass action effect of VO2 as the sole mechanism for exercise-induced oxidative stress.

Adult↗

PubMed1998

Effects of exercise training on hearing ability.

This study was designed to determine whether improvements in both cardiovascular fitness and hearing sensitivity occurred following 2 months of aerobic exercise training. Seventeen moderately-low fit (VO2 peak <32 ml/kg/min) young adults were evaluated for cardiovascular fitness and pure-tone and temporary threshold shifts (TTS) at 2, 3, and 4 kHz before and following 10 min of noise. Subjects exercised for 8 weeks by cycling on a bicycle ergometer at 70% of their peak oxygen consumption (VO2 peak). Average VO2 peak increased 34% (p < 0.05) above pre-exercise training levels. Both pure-tone hearing (2 and 3 kHz) and TTS improved following 2 months of exercise training at the evaluated frequencies (2, 3, and 4 kHz) (p < 0.05). Cardiovascular health as indicated by VO2 peak was associated with hearing sensitivity. Although the mechanisms have not been identified, these results support the existence of a cardiovascular health-hearing synergism.

Adult↗

PubMed1997

Physical activity as a natural antioxidant booster and its effect on a healthy life span.

The recent Surgeon General's report (U.S. Department of Health and Human Services, 1996) promotes regular physical activity to enhance health. A possible mechanism by which physical activity contributes to a healthy life span is via enhanced antioxidant status. The purpose of this paper is to summarize findings from human studies on life span, health, antioxidants, and the effectiveness of physical activity as a natural antioxidant booster. Epidemiological studies concur that some antioxidants are inversely related to mortality. A single bout of exercise elevates some antioxidant enzyme and coenzyme activities. Regular physical activity enhances some antioxidants; however, strenuous exercise may diminish others. Results generally show that antioxidants play a mediating role in the way in which physical activity positively affects a healthy life span.

Aging↗

PubMed1997

Circumstances and consequences of falls in independent community-dwelling older adults.

BACKGROUND: knowledge of the circumstances and consequences of falls in older adults is important for understanding the aetiology of falls as well as for effective clinical assessment and design of fall prevention strategies. Such data, however, are relatively scarce, especially in community-dwelling elders. METHOD: accidental falls (including their circumstances and consequences) occurring in 96 male and female participants between 60 and 88 years of age were monitored prospectively for 1 year. After the monitoring period, participants were divided into three groups based on fall status: non-fallers (n = 46), one-time fallers (n = 27) and recurrent fallers (n = 23). Frequency distributions were created for selected circumstances and consequences of falls and the prevalence of these consequences were examined. RESULTS: 50 participants (52%) fell during the 1 year period, amassing 91 falls. Trips and slips were the most prevalent causes of falls, accounting for 59% of falls. Falls most often occurred during the afternoon and while subjects walked on level or uneven surfaces. Fallers most commonly attributed falls to hurrying too much. Fractures resulted from five of the 91 falls and eight other falls resulted in soft tissue injuries that required treatment by a physician. There were no differences between one-time and recurrent fallers in the circumstances and consequences of falls. However, several notable differences were found between men (n = 20) and women (n = 30) who fell. Falls by men most often resulted from slips whereas falls by women most often resulted from trips. Moreover, women and men differed in the time of the year in which falls occurred, with men falling most often during winter and women during summer. CONCLUSIONS: the results of this study provide insight into the circumstances and consequences of falls among independent community-dwelling older adults and suggest some possible ways of preventing falls. Preventive services, however, should not solely target recurrent fallers, nor should the type of services necessarily differ for one-time and recurrent fallers.

Accidental Falls↗

PubMed1997

Exercise-induced oxidative stress before and after vitamin C supplementation.

Vitamin C (ascorbic acid) was supplemented (1 g/day) for 1 day and 2 weeks in the same subjects. Plasma thiobarbituric acid reacting substances (TBARS) and oxygen radical absorbance capacity (ORAC) before and after 30 min submaximal exercise were measured. Different vitamin C supplementations did not affect resting TBARS or ORAC. Following 30 min exercise, values for TBARS were 12.6 and 33% above rest with 1 day and 2 weeks of vitamin C supplementation, respectively, compared to 46% higher with placebo. ORAC did not significantly change (11%) after exercise with a placebo, nor when subjects were given vitamin C supplements for 1 day or 2 days (4.9% and 5.73%, respectively). TBARS:ORAC, a ratio representing oxidative stress, increased 32% (p < .05) with placebo compared to 5.8 and 25.8% with vitamin C supplements for 1 day and 2 weeks, respectively. It was concluded that exercise-induced oxidative stress was highest when subjects did not supplement with vitamin C compared to either 1 day or 2 weeks of vitamin C supplementation.

Adult↗

PubMed1994

Does cardiovascular health mediate hearing ability?

Exercise and noise exposure causes temporary hearing loss. Yet, a direct relationship may exist between cardiovascular health and hearing. The purpose of this study was to determine whether noise and exercise caused different levels of hearing loss depending on one's cardiovascular fitness. Twenty-eight volunteers were considered: high fit VO2peak = 48.5 +/- 1.6 ml.kg-1.min-1, N = 10), moderately fit VO2peak = 38.1 +/- 0.9 ml.kg-1.min-1, N = 9), and low fit VO2peak = 30.4 +/- 0.9 ml.kg-1.min-1, N = 9). Hearing ability at 2000, 3000, and 4000 Hz was assessed following 10 min of noise (N), exercise (E), and noise-and-exercise (N&E). The high fit group consistently demonstrated better hearing after all conditions compared to the low fit group. Significant differences between the high and low fit groups always occurred during N&E and sometimes during N. E did not cause significant hearing loss in any group. Cardiovascular health as indicated by a mean VO2peak = 48.5 ml.kg-1.min-1 is associated with less hearing loss after 10 min of either N or N&E. Although the mechanisms have not been identified, these results support the existence of a cardiovascular health-hearing synergism.

Adult↗

PubMed1993

Oxygen-radical absorbance capacity assay for antioxidants.

A relatively simple but sensitive and reliable method of quantitating the oxygen-radical absorbing capacity (ORAC) of antioxidants in serum using a few microliter is described. In this assay system, beta-phycoerythrin (beta-PE) is used as an indicator protein, 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a peroxyl radical generator, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, a water-soluble vitamin E analogue) as a control standard. Results are expressed as ORAC units, where 1 ORAC unit equals the net protection produced by 1 microM Trolox. The uniqueness of this assay is that total antioxidant capacity of a sample is estimated by taking the oxidation reaction to completion. At this point all of the nonprotein antioxidants (which include alpha-tocopherol, vitamin C, beta-carotene, uric acid, and bilirubin) and most of the albumin in the sample are oxidized by the peroxyl radical. Results are quantified by measuring the protection produced by antioxidants. This solves many problems associated with kinetics or lag-time measurements. A linear correlation of ORAC value with concentration of serum. Trolox, vitamin C, uric acid, and bovine albumin is demonstrated. The coefficient of variation within a run is found to be about 2% and from run to run about 5%. Trolox, alpha-tocopherol, vitamin C, beta-carotene, uric acid, and bilirubin completely protect beta-PE from oxidation, while bovine albumin protects beta-PE only partially. On a molar basis, the relative peroxyl radical absorbance capacity of Trolox, alpha-tocopherol acid succinate, uric acid, bilirubin, and vitamin C is 1:1:0.92:0.84:0.52. Bovine albumin per unit weight has a lower peroxyl absorbing capacity than these antioxidants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Exercise-induced oxidative stress.

The role of exercise in free radical processes is not clear; however, recent evidence suggests that elevated oxygen consumption may increase free radical activity. Direct measurement of free radical signals can be made by electron spin resonance and indirect measures include mitochondrial membrane damage, conjugated dienes, hydroperoxides, thiobarbituric acid reactive substances, short chain hydrocarbons, and oxidized nucleosides. Although exact levels are not known, the type, duration, and intensity of exercise affect biomarkers of free radical activity, as does one's training status. Oxidative stress associated with exercise-induced free radical activity seems to be better tolerated by trained subjects exercising at moderate intensity.

Animals↗

PubMed1992

Cardiovascular adjustments to high- and low-intensity exercise do not regulate temporary threshold shifts.

Sixteen adults cycled for 10 min at low and high intensities--with and without noise. The noise consisted of a 1/3 octave band-filtered noise with a 2,000 Hz center frequency at 104 dB SPL. Regardless of whether or not noise was present, systolic blood pressure increased 14% and 40% above rest during low- and high-intensity exercise, respectively. Heart rate also increased above rest (36% and 90%) during low- and high-intensity exercise, respectively. Temporary threshold shifts (TTS) at 3,000, 4,000 and 6,000 Hz could not be differentiated following low- and high-intensity exercise when noise was not present. We report significant TTS at the three frequencies following 10 min of noise exposure with or without low- or high-intensity exercise. TTS was not influenced by either the 14-40% increase in blood pressure or the 36-90% increase in heart rate induced by exercise. The inability of noise alone to influence either blood pressure or heart rate appears to implicate systems other than the cardiovascular in the regulation of hearing sensitivity.

Adult↗

PubMed1991

Effects of submaximal exercise and noise exposure on hearing loss.

A recent Scandinavian study reported that persons cycling at moderate intensity for 10 min suffered hearing loss when the exercise was accompanied by noise. The noise consisted of a 1/3 octave band-filtered noise with a 2000 Hz center frequency at 104 dB SPL. In the present study, adults cycled at 50 rev.min-1 against a force that elicited an oxygen cost equal to 70% of VO2max--an intensity frequently recommended in exercise prescriptions--with and without noise administered via headphones. Repeated measures ANOVA with three factors revealed that although a temporary hearing loss occurred following exercise-and-noise, a similar and slightly greater hearing loss occurred following noise-only. Hearing sensitivity was not significantly altered by exercise-only (p greater than .05). In general, hearing loss values were greatest between 3000 and 4000 Hz. In conclusion, temporary hearing loss was driven by noise exposure, not exercise. However, persons who choose to exercise with personal headphones or in a noisy environment should be aware of potential premature hearing loss.

Adult↗

PubMed1991

Effects of low-intensity exercise and noise exposure on temporary threshold shift.

It is not known if an individual who is susceptible to temporary threshold shift (TTS) may also suffer permanent hearing loss. Risk for hearing loss is caused by the physical properties (frequency, intensity, and duration) of noise and other possible factors including physical exercise. Seventeen subjects cycled at 40% of maximum oxygen consumption (VO2 max) with and without noise administered via personal headphones. Exercising at 40% of VO2 max is considered to be low intensity. Hearing tests before and after these two exercise conditions and a noise-only condition indicated that TTS only occurred when noise was present, that is, exercise alone did not result in TTS. Therefore TTS and subsequent hearing loss (which only persisted for 24-48 h) was found to be driven by noise exposure, not low-intensity exercise.

Adult↗

PubMed1988

MDA content increases in fast- and slow-twitch skeletal muscle with intensity of exercise in a rat.

Previous work has shown that high-intensity (HI) exercise results in total body increased production of lipid peroxidation. These results suggest that exercise induces a higher level of oxidative stress in muscles leading to the production of various peroxides and aldehydes that are potentially toxic to cells. However, these past studies were carried out only with subjects that were exercised to exhaustion or at a very high intensity. In this paper, we report how a moderate-intensity (MI) exercise, which is more normally experienced, as well as a HI acute bout of exercise influenced oxidative stress-related reactions by measuring malonaldehyde (MDA) and lipid hydroperoxides (LH) in red vastus, white vastus, and soleus muscle. The muscles from untrained male Sprague-Dawley rats were removed immediately after either a HI 1-min run at 45 m/min (n = 8) or a 20-min MI run at 20 m/min (n = 8) and compared with a control group that did not run. MI exercise resulted in a 90% increase in MDA in white vastus and a 62% increase in red vastus muscle (P less than 0.05). HI exercise resulted in a 157, 167, and 83% increase in MDA in white vastus, red vastus, and soleus muscle, respectively. LH values in red and white vastus after HI exercise increased an average of 33%, but this proved not to be statistically significant. These results confirm earlier studies that HI exercise does increase MDA in skeletal muscle, and when intensity of exercise is considerably lowered, elevated MDA is still found but at a relatively lesser amount.

Animals↗

PubMed1988

Lipid peroxidation and scavenger enzymes during exercise: adaptive response to training.

This study was designed to determine whether endurance training would influence the production of lipid peroxidation (LI-POX) by-products as indicated by malondialdehyde (MDA) at rest and after an acute exercise run. Additionally, the scavenger enzymes catalase (CAT) and superoxide dismutase (SOD) were examined to determine whether changes in LIPOX are associated with alterations in enzyme activity both at rest and after exercise. Male Sprague-Dawley rats (n = 32) were randomly assigned to either trained or sedentary groups and were killed either at rest or after 20 min of treadmill running. The training program increased oxidative capacity 64% in leg muscle. After exercise, the sedentary group demonstrated increased LIPOX levels in liver and white skeletal muscle, whereas the endurance-trained group did not show increases in LIPOX after exercise. CAT activity was higher in both red and white muscle after exercise in the trained animals. Total SOD activity was unaffected by either acute or chronic exercise. These data suggest that endurance training can result in a reduction in LIPOX levels as indicated by MDA during moderate-intensity exercise. It is possible that activation of the enzyme catalase and the increase in respiratory capacity were contributory factors responsible for regulating LIPOX after training during exercise.

Acclimatization↗