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Biomedical subjects

I Gillam

Publications and source records attributed to I Gillam.

9 recordsLinked to original sources
PubMed1997

Biochemical and ultrastructural indices of muscle damage after a twenty-one kilometre run.

Increased serum concentrations of intracellular proteins are generally accepted as good indicators of muscle damage. The mechanism of this damage is, however, poorly understood. Twenty male runners completed a 21 km run in as fast a time as possible. Blood samples were obtained from each subject just prior to, immediately after, and 24 hr after the run. Samples were analysed for haemoglobin, haematocrit, creatine kinase (CK), myoglobin (Mb) and malondialdehyde (MDA) concentrations and corrected for percentage change in plasma volume (PV). Percutaneous muscle biopsies were taken from the lateral gastrocnemius muscle of 6 of the subjects 24 hr before and 24 hr after the run and examined by electron microscopy. Mb levels in the serum increased significantly (p < 0.001) immediately post-exercise, while CK levels increased significantly (p < 0.001) at 24 hours post-exercise. The PV corrected serum MDA levels were very close (p = 0.06) to a significant increase immediately post-exercise. Ultrastructural examination of pre-exercise samples revealed evidence of muscle changes consistent with endurance exercise training, but no further damage was evident at 24 hr post-exercise. It is thus suggested that the increased serum levels of CK and Mb after the 21 km run may be a result of free radical induced cell membrane damage and increased permeability, as evidenced by elevated serum MDA levels, and not due to mechanical muscle damage.

Adult↗
PubMed1995

Changes in the susceptibility of red blood cells to oxidative and osmotic stress following submaximal exercise.

Red blood cell (RBC) susceptibility to oxidative and osmotic stress in vitro was investigated in cells from trained and untrained men before and after submaximal exercise. Whilst no significant change in peroxidative haemolysis occurred immediately after 1 h of cycling at 60% of maximal aerobic capacity (VO2max), a 20% increase was found 6h later in both groups (P < 0.05). The RBC osmotic fragility decreased by 15% immediately after exercise (P < 0.001) and this was maintained for 6h (P < 0.001). There was an associated decrease in mean cell volume (P < 0.05). Training decreased RBC susceptibility to peroxidative haemolysis (P < 0.025) but it did not influence any other parameter. These exercise-induced changes were smaller in magnitude but qualitatively similar to those found in haemopathological states involving haem-iron incorporation into membrane lipids and the short-circuiting of antioxidant protection. To explore this similarity, a more strenuous and mechanically stressful exercise test was used. Running at 75% VO2max for 45 min reduced the induction time of O2 uptake (peroxidation), consistent with reduced antioxidation capacity, and increased the maximal rate of O2 uptake in RBC challenged with cumene hydroperoxide (P < 0.001). The proportion of high-density RBC increased by 10% immediately after running (P < 0.001) but no change in membrane-incorporated haem-iron occurred. In contrast, treatment of RBC with oxidants (20-50 mumol.l-1) in vitro increased cell density and membrane incorporation of haem-iron substantially. These results showed that single episodes of submaximal exercise caused significant changes in RBC susceptibility to oxidative and osmotic stress. Such responses may account for the increase in RBC turnover found in athletes undertaking strenuous endurance training.

Adult↗
PubMed1975

An analysis of five serine transfer ribonucleic acids from Drosophila.

Crude tRNA from adult Drosophila melanogaster was fractionated on bensoylated-diethylaminoethyl cellulose columns. The eluate was assayed for both amino acid acceptance and cytokinin activity. Most of the cytokinin activity was associated with a peak of serine acceptance. The five major serine tRNAs were purified by chromatography on benzoylated-dietyhlaminoethyl cellulose and reversed phase chromatography-5 columns. The major species, tRNA7-Ser was isolated from this tRNA and was shown to be N-6-(delta-2-isopentenyl)adenosine (i-6A) on the basis of ultraviolet and mass spectral data. The nucleoside somposition of all five serine tRNAs was determined directly and by the 3-H derivative method. They all contain pseudouridine, ribothymidine, 1-methyladenosine, 5-methylcytosine, N-2-dimethylguanosine, 5, 6-hydrouridine, and 3-methylcytosine, while two contain an unidentified nucleoside, and one containes 1-methylguanosine. These techniques also confirmed the presence of i-6A in tRNA7-Ser as well as showing its presence in tRNA6-Ser and tRNA4-Ser. These three tRNA-Ser species exhibit marked changes in elution from reversed phase chromatography-5 columns as a function of temperature and this may be related to their minor base composition. The tRNAs-Ser were bound to ribosomes in response to the following triplets: tRNA2-Ser, AGU, AGC; tRNA4-Ser, UCG; tRNA5-Ser, AGU, AGC; tRNA7-Ser, UCG.

Adenosine↗
PubMed1969

Cytokinins: distribution in species of yeast transfer RNA.

Transfer RNA fractions from Saccharomyces lactis and Saccharomyces cerevisiae have been tested for cytokinin activity in the tobacco bioassay. Cysteine tRNA has been identified as a cytokinin-containing tRNA species in S. cerevisiae. Acid hydrolysates of S. lactis tRNA fractions (containing arginine tryptophan, and valine acceptor activities) and S. cerevisiae tRNA fractions (containing alanine, asparagine, aspartic acid, glutamic acid, glycine, histidine, tryptophan, and valine acceptor activities) were inactive in the tobacco bioassay. Cytokinins have been found only in those tRNA species corresponding to codons beginning with U.

Biological Assay↗
PubMedDate not supplied

1980 Melbourne marathon study.

Most of the 5423 entrants in the Melbourne 1980 Big M Marathon were non-elite athletes. A study of a stratified random sample of 459 entrants (which represented a 42% response rate) found that, while entrants reflected the community standards of disease, they pursued healthier lifestyles. Preparation for the marathon led to a number of positive changes in the health standard of runners. The principal negative consequence of marathon training was the high rate of musculoskeletal problems (30%). Before the race, only 4% of participants had an adequate fluid intake; 33% had pre-existing problems, mainly involving muscles and joints (63%) and viral or gastrointestinal illnesses (41%). These entrants had a 60% less chance of finishing the race. Symptoms during the race were reported by 92% of entrants, but most of these were not serious; only 6% of entrants were unable to finish the race. The pattern of symptoms after the race was similar to that during the race; 50% of these resolved within three hours. Ninety-seven entrants (2%) required medical attention during the race. Serious problems were rare (only in three entrants), and no runner required admission to hospital for longer than 24 hours. Entrants were at greater risk of requiring medical attention or experiencing problems during and after the race if they had a shorter preparation (less than two months), ran fewer kilometres per week (less than 60 km/week) in the last two or three months before the race, and had performed fewer long training runs (more than 24 km).

Athletic Injuries↗