Haematological and respiratory gas changes in horses and mules exercised at altitude (3800 m).

REASON FOR PERFORMING STUDY: Despite the common use of equids as visitors to high altitude mountainous environments, there are a paucity of carefully orchestrated scientific approaches. Further, again as a function of a common perceived advantage of mules over horses in these similar environments there are needs for controlled comparisons between these 2 equids. OBJECTIVE: To measure haematological and respiratory function in horses and mules at low altitude (225 m), at rest and post exercise. In addition the rate and magnitude of these changes were followed over a 13 day period at high altitude (3800 m) to contrast acclimatisation. METHODS: Resting and exercise venous blood samples (1 min post exercise) were obtained from 6 horses and 5 mules housed at 225 m (LA) and then transported to 3800 m (HA) for 13 days. The standardised exercise tests at both LA and HA consisted of trotting (3.0 m/sec) up an incline (6%) for 2 km. Data were analysed with repeated measures ANOVA (comparison of altitude acclimatisation and species) for changes in haematological and respiratory gases. RESULTS: At low altitude, no group differences were found with both resting (P = 0.69) and exercising (P = 0.74) heart rates. Resting PCV was 8% lower in the mules (P = 0.02) and 20% lower during exercise (P = 0.02). Horses had significantly higher 2,3-diphosphoglycerate (2,3-DPG)/g Hb at both rest (P = 0.003) and exercise (P = 0.03). Exercise at HA increased PCV (P = 0.03) in both groups, but the increase was attenuated in the mules compared to horses. The increase with 2,3-DPG/g Hb was expressed at HA in both groups (P = 0.001) and was also attenuated in mules (P = 0.03). Both groups were alkalotic compared to LA (P = 0.001), and there were no group differences (P = 0.95). CONCLUSION: Of the variables measured, the most notable distinction between species was identified for only PCV and 2,3-DPG with both higher in horses, at both LA and HA. While the attenuated response of PCV in mules for the same exercise might argue for an improved adaptation to altitude, the lower 2,3-DPG might not. Other variables during the exercise bout were not different between species.

Dietary intakes in Ireland of a healthy elderly population.

The aim of this paper is to assess the adequacy of the diet of individuals over 60 yr of age, participating in the 1990 Irish National Nutritional Survey. A nationwide random sample based on the most recently updated electoral register was used. Demographic information was collected. Anthropometric measurements were taken and nutrient intake was assessed using the 7-day dietary history method. The randomly selected sample of 1213 subjects was considered to be representative of the Irish population. Of those selected, 163 individuals were over 60 yr of age, 79 of whom were male and 84 female. Mean energy intakes including alcohol for males and females were 9.55 +/- 3.09MJ and 7.07 +/- 2.39MJ respectively. The main sources of energy were bread, meat and meat products, potatoes and milk. As percentage energy, protein, fat and carbohydrate intakes were 14.90 per cent, 33.97 per cent and 48.22 per cent for men and 15.39 per cent, 34.09 per cent and 49.37 per cent for women respectively. Except for vitamin D and folate, micronutrient intakes were adequate. The body mass index (BMI [weight/height2] kg/m2) for men was 25.6 and for women 26.4. Fewer than 27.8 per cent of the males and 20.2 per cent of females take part in regular physical activity. In conclusion, the diet of a healthy elderly population in Ireland is nutritionally adequate with macronutrient intake in keeping with the recommended guidelines. Overall energy intakes are lower than those of a younger age group and may account for the lower intakes of certain micronutrients. An increase in fruit and vegetable consumption would improve vitamin and mineral intake. In order to allow for a higher energy intake an increase in physical activity is desirable.

Evaluation of lifestyle, food consumption and nutrient intake patterns among Irish teenagers.

Lifestyle, food consumption and nutrient intake patterns from a randomly selected group of 390 secondary pupils aged between 12-18 were evaluated. Demographic information and anthropometric measurements included weight, height, and skinfold thickness were taken. Nutrient intake was assessed using the 7-day dietary history method, using a photographic atlas as an aid. Mean energy intakes for boys and girls aged 12-15 and 15-18 were 11.3MJ and 14MJ and 9.1MJ and 8.9MJ respectively. As percentage energy, protein fat and carbohydrate intakes varied little between the different age-sex groupings and were approximately 13.7-14.5, 35.4-37 and 46.8-50 per cent respectively. For boys micronutrient intake for iron and folate achieving only 83 and 78 per cent and 98 and 90 per cent of the recommended nutrient intake (R.N.I.) for ages 12-15 and 15-18 respectively. Mean dietary fibre intakes were approximately 19.6-25g/day for boys aged 12-18 and 17g/day for girls of a similar age. The main sources of energy were bread, meat and meat products, potatoes/chips, confectionery and preserves. Fruit and vegetable consumption was low for all groups. The majority of those surveyed consumed the traditional main meals. Snacking was also common practice. The snack foods consumed were generally of a high fat/high sugar content. 1.1 per cent boys and 2.6 per cent of girls aged 12-15 and 5.5 per cent and 8.2 per cent of boys and girls aged 15-18 respectively had a BMI greater than 26 indicating a risk of overweight. Greater than 68 per cent of girls and 79.5 per cent of boys surveyed participated in some form of sport. Boys were more physically active than girls and older girls less active than younger. In conclusion, changes from present day practices would be beneficial to reduce incidence of chronic disease for present day teenagers.

Metabolic effects of arginine in a healthy elderly population.

Recently there has been much interest in the use of arginine to stimulate immune responses and to promote wound healing. In the present study, the effect of an oral supplementation with arginine on the metabolism of 45 healthy, nonsmoking, elderly volunteers was investigated. Subjects were divided into two groups that received either arginine aspartate (17 g free arginine) (n = 30) or a placebo (n = 15). The supplements were taken for a period of 14 days. Dietary intake of food was not controlled. Blood chemistry, lipid profiles, and as an index of nutritional status, serum insulin-like growth factor-1 levels and nitrogen balance were compared before and after supplementation. Two weeks of arginine supplementation led to a significant elevation of serum insulin-like growth factor concentrations and an improved and positive nitrogen balance (2.0 +/- 0.41 g N) when compared with controls (0.11 +/- 0.47 g N; p = 0.0114). In addition the arginine-supplemented group demonstrated a decreased total serum cholesterol with a reduction in the low-density lipoprotein but not the high-density lipoprotein fraction resulting in a increase in the ratio of low- to high-density lipoprotein fraction. No adverse effects were observed at this dosage of arginine. The data suggest that oral arginine supplementation may be used safely in elderly humans.

Arginine stimulates wound healing and immune function in elderly human beings.

BACKGROUND: Experimentally, arginine enhances immune function and promotes wound healing. In this randomized double-blind study we investigated the effect of oral arginine supplementation on wound healing and T-cell function in elderly human beings (more than 65 years of age). METHODS: Thirty elderly, healthy, human volunteers (15 men and 15 women) received daily supplements of 30 gm arginine aspartate (17 gm free arginine). Fifteen volunteers (nine men and six women) received a placebo syrup. Fibroplastic wound responses were assessed by inserting a polytetrafluoroethylene catheter subcutaneously into the right deltoid region. Epithelialization was examined by creating a 2 x 2 cm split thickness wound on the lateral aspect of the upper thigh. Mitogenic response of peripheral blood lymphocytes to concanavalin A, phytohemagglutinin, pokeweed mitogen, and allogeneic stimuli was assayed at the beginning and end of supplementation. Polytetrafluoroethylene catheters were analyzed for alpha-amino nitrogen (assessment of total protein accumulation), hydroxyproline (index of reparative collagen synthesis), and DNA accumulation (index of cellular infiltration). RESULTS: Arginine supplementation for 2 weeks significantly enhanced wound catheter hydroxyproline accumulation (26.49 +/- 2.39 nmol/cm vs 17.41 +/- 2.04 nmol/cm) and total protein content (43.47 +/- 3.85 micrograms/cm vs 21.95 +/- 2.5 micrograms/cm). Arginine did not influence the DNA content of the catheters or the rate of epithelialization of the skin defect. Peripheral blood lymphocyte responses to mitogenic and allogenic stimulation were greater in the arginine supplemented group. Serum insulin-like growth factor-1 levels were significantly elevated in the arginine group. CONCLUSIONS: The data suggest that arginine supplementation may improve wound healing and immune responses in the elderly.

Tumor necrosis factor-alpha inhibits in vivo collagen synthesis.

In this study we sought to determine the in vivo role of tumor necrosis factor-alpha (TNF-alpha) at the wound-healing site. In vivo abrogation of endogenous TNF-alpha activity in experimental wounds by administration of anti-murine TNF-alpha rabbit serum resulted in a significant 77.5% increase in wound collagen deposition, as assessed by wound sponge granuloma hydroxyproline content. Administration of pharmacologic doses of recombinant murine TNF-alpha into subcutaneously inserted polyvinyl alcohol sponges resulted in an increase in collagen deposition (1594 +/- 117 vs 1014 +/- 49 and 1588 +/- 135 vs 1014 +/- 49 micrograms/100 mg sponge, for TNF-alpha in situ administration at a dose of 0.05 and 0.5 micrograms, respectively). This effect could be abolished by the simultaneous systemic treatment of the animals with the antiinflammatory drug indomethacin. The data suggest that the enhanced collagen deposition after TNF-alpha administration is a consequence of a nonspecific inflammatory activity that indirectly promotes collagen synthesis. The data also support the hypothesis that endogenous wound TNF-alpha down-regulates collagen synthesis during normal wound healing.

Effect of age on wound healing in healthy human beings.

BACKGROUND: Although the elderly clinically have a higher rate of wound complications, the physiologic effect of age on wound healing in human beings is unknown. METHODS: Healthy young (18 to 55 years of age) and elderly (more than 65 years of age) human volunteers had a 2 x 2 cm, superficial, split-thickness wound created on the anterior aspect of the thigh, and the rate of epithelialization was assessed. For studies of fibroplasia, similar groups underwent subcutaneous implantation of polytetrafluoroethylene catheters, which were removed after 14 days. Biochemical analyses of the catheters included determinations of hydroxyproline, total alpha-amino nitrogen, and DNA. RESULTS: The elderly volunteers had a significant delay of 1.9 days in epithelialization. Analyses of the subcutaneously implanted catheters showed no difference in DNA content or hydroxyproline-accumulation; however, the young volunteers had a significantly higher amount of total alpha-amino nitrogen. CONCLUSIONS: In healthy humans, aging leads to delayed epithelialization. No effect of age on collagen synthesis was noted, although accumulation of wound noncollagenous protein was decreased. This decrease may impair the mechanical properties of scarring in aged human beings.