Biomedical subjects

Marc Bonnefoy

Publications and source records attributed to Marc Bonnefoy.

7 recordsLinked to original sources

PubMed2006

Could linear MRI measurements of hippocampus differentiate normal brain aging in elderly persons from Alzheimer disease?

Although mild progressive specific structural brain changes are commonly associated with normal human aging, it is unclear whether automatic or manual measurements of these structures can differentiate normal brain aging in elderly persons from patients suffering from cognitive impairment. The objective of this study was primarily to define, with a standard high resolution MRI, the range of normal linear age-specific values for the hippocampal formation (HF), and secondarily to differentiate hippocampal atrophy in normal aging from that occurring in Alzheimer disease (AD). Two MRI-based linear measurements of the hippocampal formation at the level of the head and of the tail, standardized by the cranial dimensions, were obtained from coronal and sagittal T1-weighted MR images in 25 normal elderly subjects, and 26 patients with AD. In this study, dimensions of the HF have been standardized and they revealed normal distributions for each side and each sex: the width of the hippocampal head at the level of the amygdala was 16.42 +/- 1.9 mm, and its height 7.93 +/- 1.4 mm; the width of the tail at the level of the cerebral aqueduct was 8.54 +/- 1.2 mm, and the height 5.74 +/- 0.4 mm. There were no significant differences in standardized dimensions of the HF between sides, sexes, or in comparison to head dimensions in the two groups. In addition, the median inter-observer agreement index was 93%. In contrast, the dimensions of the hippocampal formation decreased gradually with increasing age, owing to physiological atrophy, but this atrophy is more significant in the group of AD.

Aged↗

PubMed2005

[The handling of anti-cancer drugs in elderly patients].

UNLABELLED: The management of elderly patients with cancer is not established. The use of antineoplastic agents (particularly of chemotherapy) raises a lot of questions. Efficiency and toxicity. Data come from subgroups of clinical trials and from selected populations. Chronological age itself does not contra-indicate chemotherapy. Pharmacokinetics. Physiologic and functional changes occur with aging but there is great inter-patient variability. Oral chemotherapy. Oral treatments underline the problem of compliance. Under-treatment. Elderly patients are under-represented in clinical trials. Relevant issues have to be defined individually and cancer's real place in patient's general situation has to be specified. Geriatric assessment. This tool has proved its usefulness in many domains for global management of elderly patients. A multidisciplinary team is necessary, under geriatrician coordination. The aim is to elaborate an individualized medico-social intervention program. Geriatric assessment in oncology. Its interest for cancer patients is shown by emerging reports but its routine use by oncologists is impossible. Treatment strategies. They are not validated. FUTURE: New clinical and pharmacokinetic studies are necessary in order to specify the place of the various tools and to enhance the handling of such molecules.

Administration, Oral↗

PubMed2005

Suitability of physical activity questionnaires for older adults in fall-prevention trials: a systematic review.

The purpose of the study was to identify physical activity questionnaires for older adults that might be suitable outcome measures in clinical trials of fall-injury-prevention intervention and to undertake a systematic quality assessment of their measurement properties. PubMed, CINAHL, and PsycINFO were systematically searched to identify measurements and articles reporting the methodological quality of relevant measures. Quality extraction relating to content, population, reliability, validity, responsiveness, acceptability, practicality, and feasibility was undertaken. Twelve outcome measures met the inclusion criteria. There is limited evidence about the measures' properties. None of the measures is entirely satisfactory for use in a large-scale trial at present. There is a need to develop suitable measures. The Stanford 7-day Physical Activity Recall Questionnaire and the Community Health Activities Model Program for Seniors questionnaire might be appropriate for further development. The results have implications for the designs of large-scale trials investigating many different geriatric syndromes.

Accidental Falls↗

PubMed2003

Anabolic and catabolic hormonal responses to experimental two-set low-volume resistance exercise in sedentary and active elderly people.

BACKGROUND AND AIMS: The influence of acute low-volume resistance exercise on serum growth hormone (GH), insulin-like growth factor I (IGF-I), dehydroepiandrosterone sulphate (DHEAS), total testosterone (TT) and cortisol was ascertained in elderly subjects. METHODS: Forty-seven independent, community-dwelling volunteers aged >65 years were recruited: 23 (11 men, 12 women) were sedentary individuals, and 24 (12 men, 12 women) had been regularly involved in physical activity for several years. The protocol consisted of two sets of leg extensions: one graded by loading to reach maximal power; the other consisted of 10 consecutive leg extensions using a load corresponding to maximal power. RESULTS: IGF-I levels increased immediately after exercise, returning almost completely to pre-exercise values by the 15-minute post-exercise time point. The changes in all four study groups were similar. Not any of the groups presented systematic exercise-induced changes in circulating GH, DHEAS and TT levels. With respect to pre-exercise cortisol levels, significant decreases were observed both at the immediate and at the 15-minute post-exercise time points. These changes were independent of gender and physical activity level. CONCLUSIONS: Our data indicate that low-volume resistance exercise may decrease cortisol levels and increase serum anabolic/catabolic hormone ratios. In view of the experimental character of our resistance training protocol and the lack of control-day data, these results should be corroborated by long-term low-volume resistance training programs.

Aged↗

PubMed2002

[Antioxidants to slow aging, facts and perspectives].

FREE RADICALS AND THE THEORY OF AGING: Severe oxidative stress progressively leads to cell dysfunction and ultimately cell death. Oxidative stress is defined as an imbalance between pro-oxidants and/or free radicals on the one hand, and anti-oxidizing systems on the other. The oxygen required for living may indirectly be responsible for negative effects; these deleterious effects are due to the production of free radicals, which are toxic for the cells (superoxide anions, hydroxyl radicals, peroxyl radicals, hydrogen peroxide, hydroperoxides and peroxinitrite anions). Free radical attacks are responsible for cell damage and the targeted cells are represented by the cell membranes, which are particularly rich in unsaturated fatty acids, sensitive to oxidation reactions; DNA is also the target of severe attacks by these reactive oxygen species (ROS). THE DEFENCE SYSTEMS: These are represented by the enzymes and free radical captors. The latter are readily oxidizable composites. The free radical captor or neutralization systems of these ROS use a collection of mechanisms, vitamins (E and C), enzymes [superoxide dismutase (SOD), glutathion peroxidase (GPx) and others], and glutathion reductase (GSH), capable of neutralizing peroxinitrite. The efficacy of this system is dependent on the genome for the enzymatic defence systems, and on nutrition for the vitamins. Some strategies aimed at reducing oxidative stress-related alterations have been performed in animals. However, only a few can be used and are efficient in humans, such as avoidance of unfavourable environmental conditions (radiation, dietary carcinogens, smoking...) and antioxidant dietary supplementation. DIETARY SUPPLEMENTATION: Epidemiological data suggest that antioxidants may have a beneficial effect on many age-related diseases: atherosclerosis, cancer, some neurodegenerative and ocular diseases. However, the widespread use of supplements is hampered by several factors: the lack of prospective and controlled studies; insufficient knowledge on the pro-oxidant, oxidant and ant-oxidant properties of the various supplements; growing evidence that free radicals are not only by-products, but also play an important role in cell signal transduction, apoptosis and infection control. RECOMMENDATIONS: Although current data indicate that antioxidants cannot prolong maximal life span, the beneficial impact of antioxidants on various age-related degenerative diseases may forecast an improvement in life span and enhance quality of life. The current lack of sufficient data does not permit the systematic recommendation of anti-oxidants. Nevertheless, antioxidant-rich diets with fruit and vegetables should be recommended.

Aging↗

PubMed2002

[Physical activity to delay the effects of aging on mobility].

SARCOPENIA: Aging is accompanied by the progressive reduction in cardio-pulmonary capacity and muscular strength. These two phenomena are partly related to the decrease in muscle mass, or sarcopenia. CARDIO-PULMONARY CAPACITY: Measured by maximum oxygen consumption (VO2max), it demonstrates the individual's capacity for movement. It is also the principle marker of mortality due to cardiovascular events. VO2max decreases by around 0.8% each year, in close correlation with the evolution in muscle mass. These phenomena are partly related to reduced physical activity and, particularly, intense activity greater than 6 MET. Regular practice of moderately intense physical activity can maintain VO2max at a level 20 to 35% superior to that of the mean level in the same age range, and is associated with increased autonomic nervous system activity. DECREASED MUSCULAR STRENGTH: Sarcopenia and the proportional decrease in fast-twitch muscle fibers are related to a reduction in physical activity. The decrease in muscular strength is a handicapping factor and increases the risk of falls. Two sessions of training per week can increase by more than 30% the strength of the muscles concerned, by increasing the muscle volume and the maximum frequency of emission of motoneuron influx. The production of somatotropin, insulin-like growth factor-I and testosterone can also be increased. High-resistance exercises are themselves sufficient to increase bone density. In the light of these advantages, the practice of workouts in endurance and strength should be encouraged.

Accidental Falls↗

PubMedDate not supplied

[Preventing dependency in elderly persons: randomized study in the community].

The number of elderly people aged > 85 years will double by the year 2020. Helping the elderly to live independently at home is a major challenge for society. Physical exercise and protein energy intake might both be effective in preventing dependency. This paper describes the organisation of an ongoing study aimed at evaluating the preventive effect of such measures, involving 102 elderly persons randomised into two groups, one receiving preventive measures but not the other. The study organisation was based on representatives and selected workers from associations involved in home assistance for elderly. Their role consisted in recruiting persons for participation in the trial, encouraging them to perform exercises and take dietary supplements, and notifying the research team of all health-related events. This organisation has reached its objectives, even though the supervision of the domestic workers needs to be improved. This network, comprising stable workers (14 years of work experience on average in this study) offers the potential for future research in the community to evaluate preventive measures.

Activities of Daily Living↗