Fat oxidation in men and women endurance athletes in running and cycling.

Recent studies showed that the maximal fat oxidation seems to be different in men and women and that it can be influenced by type and intensity of exercise. Nineteen endurance trained male (V.O (2)peak 61.3 +/- 4.4 ml x kg (-1) x min (-1)) and 17 female (V.O (2)peak 52.8 +/- 4.5 ml x kg (-1) x min (-1)) athletes were studied over 30 min at 55, 65 and 75 % V.O (2)peak on a treadmill and a cycling ergometer in order to find the intensity and kind of exercise with the highest absolute fat oxidation. For women, normalised (per body weight) fat oxidation was higher at 75 % V.O (2)peak than at 55 % V.O (2)peak for both running (p = 0.02) and cycling (p = 0.01). Women also oxidised a significantly higher percentage of fat with regard to total energy expenditure than men in running (p = 0.02) and cycling (p = 0.004). Normalised carbohydrate oxidation was significantly higher for men at each tested intensity (p < 0.05) and compared to kind of exercise in men (p = 0.006) and women (p = 0.002) in cycling than in running. Men and women showed a significantly higher normalised fat oxidation for running compared to cycling (p = 0.01). Cycling produced in men (p = 0.06) and women (p = 0.001) significantly more lactate than running. In summary, we found at 75 % V.O (2)peak a higher fat oxidation rate than at 65 % V.O (2)peak and 55 % V.O (2)peak for men and women in cycling and running. This is coincident with lactate threshold in men and women in cycling but not in running, where lactate threshold is higher than 75 % V.O (2)peak.

Fat oxidation at different intensities in wheelchair racing.

STUDY DESIGN: Determination of fat oxidation at three different intensities in trained wheelchair athletes on the treadmill. OBJECTIVE: The aim of the study was to assess the level and highest rate of fat oxidation in endurance-trained wheelchair athletes for recommendation on endurance training. SETTING: Institute of Sports Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland. METHODS: Nine (seven men and two women) endurance-trained wheelchair athletes (VO(2peak) 40.2+/-6.7 ml/kg/min) were studied over 20 min at 55, 65 and 75% VO(2peak) on a treadmill in their own racing wheelchairs in order to find the exercise intensity with the highest absolute fat oxidation. RESULTS: As presumed, total energy expenditure for wheelchair racing was highest at 75% VO(2peak), while absolute fat oxidation was statistically not significantly different at the three tested intensities. Percentage of energy expenditure from fat oxidation decreased with increasing intensity from 31.4% at 55% VO(2peak) to 20.9% at 75% VO(2peak), while percentage from carbohydrate oxidation increased from 68.6% at 55% VO(2peak) to 79.1% at 75% VO(2peak). CONCLUSION: For wheelchair athletes, we recommend training of fat metabolism for endurance exercise at an intensity of 55% VO(2peak), because absolute fat metabolism is not higher at higher intensities but less carbohydrates are used at lower intensity levels. At lower intensities, exercise can be performed over a longer time before the emptied glycogen stores will limit exercise duration. This may apply especially to paraplegic subjects whose active muscle mass is limited in contrast to able-bodied athletes.

Poor quality of oocytes from Xenopus laevis used in laboratory experiments: prevention by use of antiseptic surgical technique and antibiotic supplementation.

BACKGROUND AND PURPOSE: Episodic phases of continuous poor-quality oocytes obtained from South American Clawed Frogs (Xenopus laevis) often are observed. In publications dealing with the surgical technique of oocyte removal, the frogs' robust constitution and resistance against infections provided by magainins are pointed out. For this reason, clean rather than sterile conditions for the surgical procedure are mostly recommended. However, in most instances, antibiotics are added to the buffer medium when in vitro experiments are performed using oocytes. METHODS: After a long phase of poor oocyte quality at our facility, involving oocytes that had been obtained by use of a "clean" surgical procedure, we subsequently cultured oocytes in a buffer medium containing the three antibiotics: penicillin G, gentamicin, and streptomycin. RESULTS: During DNA injection experiments, the oocytes developed black spots on their surface by postoperative day two. Pure culture of the gram-negative non-fermentative rod Pseudomonas fluorescens was obtained from the impaired oocytes; the isolate was resistant to the three antibiotics. By contrast, after aseptic surgical removal and culture of oocytes in buffer medium containing the antibiotics tetracycline and gentamicin, perfect oocytes without bacterial contamination were obtained. CONCLUSION: Whenever impaired oocyte quality is observed, microbial contamination should be considered as a possible cause.

Anthelmintic treatment to eradicate cutaneous capillariasis in a colony of South African clawed frogs (Xenopus laevis).

The nematode Capillaria xenopodis (Pseudocapillaroides xenopi), a skin parasite of South African clawed frogs (Xenopus laevis), is quite common in laboratory animal facilities. It causes serious skin changes and may further lead to wasting and death of affected frogs. Various treatment protocols, using the anthelmintics ivermectin and levamisole, were successively tested for practicability of elimination of the parasite from a colony of clawed frogs. Nematodes were reduced below diagnostic levels by various methods of application of ivermectin (orally or by injection into the dorsal lymph sac, twice at intervals of 10 to 14 days). However, nematodes were found again in the treated animals 1 to 3 months later. Treatment by use of ivermectin-medicated tank water is not feasible due to its low water solubility. Elimination of the parasite was reliably achieved by use of levamisole-medicated tank water. Relapses were not seen during the 18-month posttreatment observation period. Levamisole concentration was 12 mg/L of water, with 4.17, 5.00, or 6.25 L of tank water/frog, and 50, 60, or 75 mg of levamisole available/frog, for at least 4 days, with treatments repeated after 10 to 14 days. Results were reproducible in two trials each with five tanks containing, in turn, four or five frogs each. A treatment trial carried out with a group of 20 adult frogs exposed to 12 mg of levamisole/L of tank water, but with only 2.5 L of tank water/frog (i.e., only 30 mg of levamisole available/animal), was not effective in eradicating the parasites. Not only the drug concentration, but also the amount of drug available per animal seems to be of importance. In contrast to thiabendazole, which is often reported in literature as treatment for cutaneous capillariasis, negative side effects were not observed with use of levamisole.

Hereditary compulsive self-mutillating behaviour in laboratory rabbits.

During the last few years an increasing number of cases of extensive automutilation has been observed in a rabbit breeding colony of Checkered crosses. Digits and pads of the front feet were traumatized. No other behavioural abnormalities or signs of disease were evident. Self-mutillation was seen both in stock, breeding and experimental animals, in rabbits kept singly in cages and in those housed in groups on the ground, in rabbits kept in different buildings and under the care of different staff members. This behavioural abnormality of Checkered crosses has also been observed in animals after being placed into other institutions or private homes. No evidence of an agent responsible for the occurrence of self-injury could be found with parasitological, mycological, histological, clinical or haematological examination. Twelve to 16 animals are affected yearly in a colony varying in size between 130 and 230 rabbits. Following complete healing, relapses occurred up to 3 times per year, on either the same or the opposite front foot. In the last 21 cases episodes of automutillation could be regularly interrupted with the dopamine antagonist, haloperidol. Similar signs of auto-mutillation were never seen in animals of another breeding line kept in the same building and under the same conditions nor in animals brought in from other breeding colonies. A relatively high coefficient of inbreeding can be presupposed in this 15-year-old breeding colony of Checkered crosses. A genetic predisposition for the behavioural anomaly described appears very likely.