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Biomedical subjects

A Garnham

Publications and source records attributed to A Garnham.

At least 19 recordsLinked to original sources
PubMed2003

Microtibial embolectomy.

BACKGROUND: microtibial embolectomy is an important technique in cases of limb threatening acute arterial occlusion affecting native crural and pedal vessels. It is particularly useful when thrombolysis is contraindicated or ineffective as in "trash foot". METHODS: in order to evaluate the efficacy of this technique, a retrospective case note review was carried out for patients undergoing microtibial embolectomy from 1990 to 1999. Data collected included the causes and degree of ischaemia, additional procedures required, vessel patency, limb salvage and complications encountered. RESULTS: twenty-two limbs underwent exploration of the crural/pedal vessels with ankle level arteriotomies under local anaesthetic in 12 cases, general anaesthetic in nine and epidural in one. The causes of ischaemia were cardiac emboli (8), "trash foot" (7), emboli from aortic and popliteal aneurysms (3) and thrombotic occlusion of crural vessels (4). The vessel patency rate was 69% and limb salvage rate 62% (13/21) up to 5-years follow-up. Six of the seven cases with "trash foot" were salvaged while one required an amputation at 3-months post-operatively. The 30-day mortality was 22% (5/22). CONCLUSIONS: microtibial embolectomy is effective in acute occlusion of the crural/pedal arteries including cases of "trash foot", offering limb salvage to a worthwhile proportion of cases.

Aged↗
PubMed2002

UCP3 protein expression is lower in type I, IIa and IIx muscle fiber types of endurance-trained compared to untrained subjects.

Uncoupling protein 3 (UCP3) is a muscle mitochondrial protein believed to uncouple the respiratory chain, producing heat and reducing aerobic ATP production. Our aim was to quantify and compare the UCP3 protein levels in type I, IIa and IIx skeletal muscle fibers of endurance-trained (Tr) and healthy untrained (UTr) individuals. UCP3 protein content was quantified using Western blot and immunofluorescence. Skeletal muscle fiber type was determined by both an enzymatic ATPase stain and immunofluorescence. UCP3 protein expression measured in skeletal muscle biopsies was 46% lower ( P=0.01) in the Tr compared to the UTr group. UCP3 protein expression in the different muscle fibers was expressed as follows; IIx>IIa>I in the fibers for both groups ( P<0.0167) but was lower in all fiber types of the Tr when compared to the UTr subjects ( P<0.001). Our results show that training status did not change the skeletal muscle fiber hierarchical UCP3 protein expression in the different fiber types. However, it affected UCP3 content more in type I and type IIa than in the type IIx muscle fibers. We suggest that this decrease may be in relation to the relative improvement in the antioxidant defense systems of the skeletal muscle fibers and that it might, as a consequence, participate in the training induced improvement in mechanical efficiency.

Adult↗
PubMed2002

The playing habits and other commitments of elite junior Australian football players.

The Victorian Football League Under 18 (VFL U18) competition provides a pathway to the elite senior level of Australian football. Players involved in the VFL U18 competition also play football in other contexts, including for school and local clubs, and can have considerable additional work and educational demands. A total of 103 elite junior Australian football players from six VFL U18 clubs participated in a survey that asked about their football playing habits and other commitments. The median age of players when they first joined their VFL U18 squad was 16.3 years. The players participated in a median of five weekly training sessions during the last two weeks of the 1999 preseason and played a median of five preseason games. Fifty percent of the players expected to participate in 3-4 training sessions per week and 25% expected to play more than two games per week during the 1999 season. Half of the players reported ambitions to play Australian Football League (AFL) football. Further research is needed to determine whether or not high participation levels have negative impacts on performance and injury risk in these players.

Adolescent↗
PubMed2002

Slow component of [V]O(2) kinetics: the effect of training status, fibre type, UCP3 mRNA and citrate synthase activity.

OBJECTIVE: In healthy individuals performing constant-load exercise at intensities above the lactate threshold a secondary rise in pulmonary oxygen uptake ([V]O(2)) occurs. [V]O(2) reaches a maximum and exhaustion rapidly prevails for a range of work rates lower than the maximal work rate achieved during a conventional rapid-incremental test. This phenomenon is called the slow component (SC) of [V]O(2) kinetics and represents an increase in [V]O(2) without an increase in work rate. Although still under debate, the magnitude of the SC is believed to be associated with the percentage of type II muscle fibres and their recruitment. In this study we investigated the relationship between the magnitude of the relative SC, citrate synthase activity, UCP2 and UCP3 mRNA levels and muscle fibre composition in both endurance-trained and recreationally active subjects. METHOD: The magnitude of the relative SC was measured in 12 endurance-trained (Tr) and 15 recreationally active (RA) male subjects. The magnitude of the relative SC was determined as the difference between the end-exercise [V]O(2) and 3 min [V]O(2) divided by the difference between end-exercise [V]O(2) and baseline [V]O(2). UCP2 and UCP3 mRNA expression in the vastus lateralis was measured by RT-PCR with beta-actin mRNA used as an internal control. These values were also normalized against cytochrome-b mRNA to control for training induced changes in mitochondria when comparing the Tr and RA groups. Type I, IIa and IIx skeletal muscle fibre composition was determined using a routine myosin ATPase histochemical staining technique. Citrate synthase (CS) activity was measured using spectrophotometric detection. RESULTS: The magnitude of the relative SC of the Tr group had the highest correlation with citrate synthase activity (r=-0.90, P<0.001) and that of the RA group with [V]O(2) peak (r=-0.68, P<0.01). For the Tr group other correlations with the magnitude of the relative SC included UCP3 mRNA levels (r=0.69, P<0.05) and the percentage of type I fibres (r=-0.58, P<0.05), while for the RA group they included UCP3 mRNA (r=0.58, P<0.05) and the percentage of type IIa muscle fibres (r=0.59, P<0.05). The Tr subjects had a lower relative SC (P=0.04) and a lower expression of UCP2 (P=0.04), and UCP3 mRNA (P=0.01) than the RA subjects. When the groups were combined the magnitude of the relative SC correlated with UCP3 mRNA (r=0.70, P<0.01), percentage of type IIa muscle fibres (r=0.60, P<0.01) and [V]O(2) peak (r=-0.73, P<0.01). Additionally UCP3 mRNA correlated with the percentage of type IIa muscle fibres (r=0.63, P<0.001). CONCLUSION: Citrate synthase activity and [V]O(2) peak are indicators of aerobic fitness. The high negative correlations between the magnitude of the relative SC and citrate synthase activity and [V]O(2) peak, of the Tr and RA subjects, respectively, suggests that the magnitude of the relative SC is inversely correlated with aerobic fitness. Additionally the correlations between UCP3 mRNA and the magnitude of the relative SC for both groups individually and combined suggest that the uncoupling activity of the UCP3 protein may also influence the magnitude of the relative SC.

Adult↗
PubMed2002

Safety attitudes and beliefs of junior Australian football players.

OBJECTIVES: To describe the safety attitudes and beliefs of junior (aged 16-18 years) Australian football players. SETTING: Six Victorian Football League Under 18 (VFL U18) clubs in Victoria, Australia. METHODS: Cross sectional survey. Altogether 103 players completed a self report questionnaire about their safety beliefs and perceptions of support when injured, across three contexts in which they played: VFL U18 club, local club, and school. RESULTS: Although only 6% believed it was safe to play with injuries, 58% were willing to risk doing so. This increased to almost 80% when players perceived that their chances of being selected to play for a senior elite team would be adversely affected if they did not play. There were significant differences in the perceived level of support for injured players and in the ranking of safety as a high priority across the three settings. In general, the VFL U18 clubs were perceived as providing good support for injured players and giving a high priority to safety issues, but local clubs and particularly schools were perceived to address these issues less well. CONCLUSIONS: Junior Australian football players have certain beliefs and perceptions in relation to injury risk that have the potential to increase injuries. These negative beliefs need to be addressed in any comprehensive injury prevention strategy aimed at these players.

Adolescent↗
PubMed2001

Exercise increases serum Hsp72 in humans.

Recent evidence suggests that heat shock proteins (Hsps) may have an important systemic role as a signal to activate the immune system. Since acute exercise is known to induce Hsp72 (the inducible form of the 70-kDa family of Hsp) in a variety of tissues including contracting skeletal muscle, we hypothesized that such exercise would result in the release of Hsp72 from stressed cells into the blood. Six humans (5 males, 1 female) ran on a treadmill for 60 minutes at a workload corresponding to 70% of their peak oxygen consumption. Blood was sampled from a forearm vein at rest (R), 30 minutes during exercise, immediately postexercise (60 minutes), and 2, 8, and 24 hours after exercise. These samples were analyzed for serum Hsp72 protein. In addition, plasma creatine kinase (CK) was measured at these time points as a crude marker of muscle damage. With the exception of the sample collected at 30 minutes, muscle biopsies (n = 5 males) were also obtained from the vastus lateralis at the time of blood sampling and analyzed for Hsp72 gene and protein expression. Serum Hsp72 protein increased from rest, both during and after exercise (0.13 0.10 vs 0.87+/-0.24 and 1.02+/-0.41 ng/mL at rest, 30 and 60 minutes, respectively, P < 0.05, mean SE). In addition, plasma CK was elevated (P < 0.05) 8 hours postexercise. Skeletal muscle Hsp72 mRNA expression increased 6.5-fold (P < 0.05) from rest 2 hours postexercise, and although there was a tendency for Hsp72 protein expression to be elevated 2 and 8 hours following exercise compared with rest, results were not statistically significant. The increase in serum Hsp72 preceded any increase in Hsp72 gene or protein expression in contracting muscle, suggesting that Hsp72 was released from other tissues or organs. This study is the first to demonstrate that acute exercise can increase Hsp72 in the peripheral circulation, suggesting that during stress these proteins may indeed have a systemic role.

Adult↗
PubMed2000

Activation of human leukocytes by acute hypoxia.

Exposure of human leukocytes to 12% and 6% O(2) in vitro resulted in striking ultrastructural and morphological changes. These changes included the appearance of crater-like holes, a reduction in granular size and disruption of the cellular membrane. The implications of these findings is discussed.

Adult↗
PubMed1998

Can any ostrich fly?: some new data on belief bias in syllogistic reasoning.

According to one version of the mental models theory (Oakhill, J.V., Johnson-Laird, P.N., Garnham, A., 1989. Believability and syllogistic reasoning. Cognition 31, 117-140) beliefs exert their influence on reasoning in three ways. First they can affect the interpretation of the premises, for example by conversion. Second, they can curtail the search for alternative models of the premises, if an initial model supports a believable conclusion. Third, they can act as a filter on any conclusion that is eventually generated. This last influence is important in explaining the effects of belief bias in one-model syllogisms with no convertible premises, since such syllogisms, by definition, have no alternative models. However, the most natural interpretation of such a filter is that it filters out conclusions and leads to the response 'no valid conclusion'. The present study, which was conducted with groups of both British and Italian subjects, looked at the effect of prior knowledge on syllogistic reasoning, and showed that: (1) invalid conclusions for such one model syllogisms, either thematic or abstract, are typically not of the type 'no valid conclusion', but state invalid relations between the end terms; (2) belief-bias is completely suppressed when previous knowledge is incompatible with the premises, and therefore the premises themselves are always considered. The results are compatible with a version of the mental models theory in which a representation of prior knowledge precedes modelling of the premises, which are then incorporated into the representation of this knowledge. The relation between this theory and other accounts of belief bias in syllogistic reasoning, and the implications of these findings for reasoning more generally, are considered.

Adult↗
PubMed1996

The use of stereotypical gender information in constructing a mental model: evidence from English and Spanish.

Four experiments were carried out to investigate how general knowledge about the stereotypical gender of participants in a text influences comprehension. A self-paced reading task was used to present short texts comprising one, two, or three sentences. The first sentence of each text introduced a stereotypically masculine or feminine participant (e.g. doctor, nurse), or a neutral one. The last sentence introduced a pronoun (he/she) that could match or mismatch the gender of the referent. The first experiment, which was carried out in English, showed that reading times for the last sentence were longer when there was a mismatch than when there was a match between the gender of the pronoun in the last sentence and the stereotypical gender of the referent in the first sentence. In contrast to English, the gender of the participant can be disambiguated by a preceding article (el/la) in Spanish. The results of the second, third, and fourth experiments, which were carried out in Spanish, showed that reading times for the first sentences were longer when there was a mismatch than when there was a match between the gender of the article and the stereotypical gender of the participant. However, reading times for the last sentences did not differ. Overall, the results suggest that information about the stereotypical gender of the participants in a text is incorporated into the representation as soon as it becomes available, and that it affects the ease with which the text is understood.

Cognition↗
PubMed1993

Development of a catheterised bladder model to evaluate urinary drainage equipment.

A catheterised bladder model was developed to examine the design features of urinary drainage bags. The drainage bag of 4 commonly used products was inoculated with either Escherichia coli or Proteus mirabilis. The speed of retrograde contamination towards the "bladder" was determined over 96 h. The effect of lifting the drainage bag above the level of the "bladder" was examined also. Within 4 days micro-organisms were detected in the backflow valves/drip chambers of all products, but contamination had not progressed as far as the catheter. Ps. mirabilis appeared to migrate more rapidly than Esch. coli. Lifting the drainage bag had no effect on the migration of either organism. The implications of these results for clinical practice are discussed.

Drainage↗
PubMed1989

A unified theory of the meaning of some spatial relational terms.

This paper presents a unified account of the meaning of the spatial relational terms right, left, in front of, behind, above and below. It claims that each term has three types of meanings, basic, deictic and intrinsic, and that the definitions of each type of meaning are identical in form for all six terms. Restrictions on the use of the terms, which are different for above and below than for the rest, are explained by a general constraint on all uses of spatial relational terms, the framework vertical constraint. This constraint depends on the existence of a fourth type of meaning for above and below, one defined by the framework in which the related objects are located. It is argued that a theory centred on the framework vertical constraint is preferable to one centred on the principle of canonical orientation (Levelt, 1984).

Gravitation↗
PubMed1989

Believability and syllogistic reasoning.

In this paper we investigate the locus of believability effects in syllogistic reasoning. We identify three points in the reasoning process at which such effects could occur: the initial interpretation of premises, the examination of alternative representations of them (in all of which any valid conclusion must be true), and the "filtering" of putative conclusions. The effect of beliefs at the first of these loci is well established. In this paper we report three experiments that examine whether beliefs have an effect at the other two loci. In experiments 1 and 2 subjects drew their own conclusions from syllogisms that suggested believable or unbelievable ones. In the third experiment they evaluated conclusions that were presented to them. The data show that beliefs both affect the examination of alternative models and act as a filter on putative conclusions. We conclude by showing how some types of problem and some problem contents make the existence of alternative models more obvious than others.

Humans↗