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D Bishop

Publications and source records attributed to D Bishop.

At least 37 records · Page 2Linked to original sources
PubMed2003

Comparison of Agrobacterium-mediated transformation of four barley cultivars using the GFP and GUS reporter genes.

Experiments were conducted to produce transgenic barley plants following infection of immature embryos with Agrobacterium tumefaciens. Transformed callus was obtained using hygromycin resistance as a selectable marker and either green fluorescent protein (GFP) or beta-glucuronidase (GUS) as a reporter. Significantly reduced plant transformation frequencies were obtained with the GFP gene compared to GUS. However, GFP proved to be an excellent reporter of early transformation events and was used to compare four barley cultivars for efficiency in two phases of transformation: the generation of stably transformed barley callus and the regeneration of plantlets from transformed callus. Transformed callus was generated at a high frequency (47-76%) in all four cultivars. Regeneration of transformed plantlets was also achieved for all four cultivars although the frequency was much higher for Golden Promise than for the other three genotypes, reiterating that genotype is an important determinant in the regenerative ability of barley. This study has demonstrated for the first time that Agrobacterium-mediated transformation can be used to transform the Australian cultivars Sloop and Chebec.

Agrobacterium tumefaciens↗
PubMed2003

Predictors of repeated-sprint ability in elite female hockey players.

The ability to maintain maximal power over a series of sprints may depend, in part, on the resynthesis of PCr and the buffering of hydrogen ions (H+). As a result, repeated-sprint ability may be related to VO2peak and changes in plasma pH. Fourteen elite female field-hockey players (Mean +/- SD body mass: 61.1 +/- 5.9 kg and VO2pea: 55.7 +/- 3.2 mL x kg(-1) x min(-1)) participated in this investigation. Tests consisted of a repeated-sprint ability test (5 x 6-s all-out sprints every 30 s) and a VO2peak test. Capillary and venous blood was sampled before and after the 5 x 6-s cycle test for the determination of lactate concentration and pH. There were no significant correlations between VO2peak (mL x kg(-1) x min(-1)) and total work (J.kg(-1); r = 0.35), or power decrement (r = 0.30) during the repeated-sprint ability test. There was, however, a significant correlation between power decrement and change in plasma [H+] (r = 0.66; P < 0.05). The results of this study show that in a homogenous group of elite, team-sport athletes, VO2peak (mL x kg(-1) x min(-1)) is not a strong predictor of repeated-sprint ability. However, in this group, there is a significant correlation between change in plasma [H+] and repeated-sprint ability.

Adult↗
PubMed2003

Effect of wearing an ice cooling jacket on repeat sprint performance in warm/humid conditions.

OBJECTIVE: To examine the effect of cooling the skin with an ice jacket before and between exercise bouts (to simulate quarter and half time breaks) on prolonged repeat sprint exercise performance in warm/humid conditions. METHODS: After an initial familiarisation session, seven trained male hockey players performed two testing sessions (seven days apart), comprising an 80 minute intermittent, repeat sprint cycling exercise protocol inside a climate chamber set at 30 degrees C and 60% relative humidity. On one occasion a skin cooling procedure was implemented (in random counterbalanced order), with subjects wearing an ice cooling jacket both before (for five minutes) and in the recovery periods (2 x 5 min and 1 x 10 min) during the test. Measures of performance (work done and power output on each sprint), heart rates, blood lactate concentrations, core (rectal) and skin temperatures, sweat loss, perceived exertion, and ratings of thirst, thermal discomfort, and fatigue were obtained in both trials. RESULTS: In the cooling condition, chest (torso) skin temperature, thermal discomfort, and rating of thirst were all significantly lower (p<0.05), but no significant difference (p>0.05) was observed between conditions for measures of work done, power output, heart rate, blood lactate concentration, core or mean skin temperature, perceived exertion, sweat loss, or ratings of fatigue. However, high effect sizes indicated trends to lowered lactate concentrations, sweat loss, and mean skin temperatures in the cooling condition. CONCLUSIONS: The intermittent use of an ice cooling jacket, both before and during a repeat sprint cycling protocol in warm/humid conditions, did not improve physical performance, although the perception of thermal load was reduced. Longer periods of cooling both before and during exercise (to lower mean skin temperature by a greater degree than observed here) may be necessary to produce such a change.

Adult↗
PubMed2003

A comparison between land and sand-based tests for beach volleyball assessment.

AIM: Vertical-jumping ability is critical for success in beach volleyball. However, as beach volleyball is a relatively new sport, its testing procedures have largely been adopted from the indoor game and are consequently performed on firm surfaces. The purpose of this paper was to determine whether vertical-jumping ability is specific to the test surface (i.e., wood or sand). METHODS: Eighteen beach volleyball players performed 4 different vertical jumps on a wood surface or on the sand, followed by the alternate surface, in a random, counterbalanced order. Correlation coefficients were calculated to determine the degree of association between the 4 jumps and between the test results on the 2 surfaces. RESULTS: When compared with the land condition, all jump heights were significantly lower when performed on sand (p<0.05). There was however, a significant correlation between the land and sand results for all jumps (mean r=0.93; p<0.05). While all 4 vertical jump variations were significantly correlated with each other (mean r=0.91; p<0.05), the correlation between static jumps and the spike jump (3-step run up) tended to be lower. CONCLUSION: It is likely that vertical jump height on sand is lower than on land due to a reduction in the ground reaction force. However, despite this, the strong correlation between land and sand scores suggests that vertical-jumping ability exists as a general quality and is not greatly influenced by test surface in the subjects tested. This suggests that land-based tests can be used to assess sand jumping ability in experienced beach volleyball players.

Adult↗
PubMed2002

Observation of structures of chain vortices inside anisotropic high- Tc superconductors.

In order to elucidate the formation mechanism of unconventional arrangements of vortices in high- Tc superconducting thin films at an inclined magnetic field to the layer plane, we investigated the structures of vortex lines inside the films by Lorentz microscopy using our 1-MV field-emission electron microscope. Our observation results concluded that vortex lines are tilted to form linear chains in YBaCu3O(7,8). Vortex lines in the chain-lattice state in Bi2Sr2CaCu2O(8+delta), on the other hand, are all perpendicular to the layer plane, and therefore only vortices lined up along Josephson vortices form chains.

Journal Article↗
PubMed2001

The validity of a repeated sprint ability test.

Many team sports require participants to repeatedly produce maximal or near maximal sprints of short duration (1-7s) with brief recovery periods, over an extended period of time (60-90 min). Therefore, an important fitness component for these sports is what is often termed repeated sprint ability (RSA). A variety of tests have been devised to assess RSA. However, while the reliability of some of these tests has been reported, there has been no published attempt to assess the validity of RSA tests. The purpose of the present paper was to assess the validity of a popular RSA test--the 5 x 6 s cycle test. Ten moderately-trained males (Mean+/-SD age: 23.6+/-3.0 yrs, mass: 71.8+/-7.4 kg, peak VO2: 46.32+/-4.16 ml.kg(-1)min(-1)) participated in the investigation. Following familiarisation, subjects reported to the laboratory at the same time of day, on three occasions, each separated by at least 48 hours. Testing consisted of a 5 x 6 s cycle test (5 x 6 s maximal sprints every 30 s), a graded exercise test (GXT) and a simulated game (3 x 15 min periods separated by five min). The simulated game consisted of a 1-min circuit that was repeated 15 times in each period. The circuit replicated typical movement patterns observed during motion analysis of field hockey games. Each circuit commenced with a 15-m maximum sprint through timing gates. Time to run 5, 10 and 15 m was recorded. Oxygen consumption was measured during both the GXT and the simulated game with a portable gas analysis system (Cosmed K4 b2, Italy). Correlation coefficients between dependent variables were calculated using Pearson's Product Moment (r). There was a significant correlation between power decrement during the 5 x 6 s cycle test and decrement in 15-m time across the three periods (r = 0.76, P<0.05), but not decrement in 10-m time (r = 0.54) or 5-m time (r = 0.42). These results suggest that the 5 x 6 s cycle test is valid for assessing the decrement in 15-m time, but not the decrement in 5 or 10m time. Thus, one measure of RSA (sprint decrement) appears to be specific to the test protocol, rather than a general quality. The most likely explanation is that the energy requirements of the 5 x 6 s cycle test more closely match those required to repeatedly run 15 m (mean time = 2.74 s) than to repeatedly run 10 m (mean time = 1.97 s) or 5 m (mean time = 1.13 s). It is therefore suggested that, while the 5 x 6 s cycle test is often used to assess RSA ability in a wide range of sports, it may need to be modified to reflect the common sprint distances found in specific sports.

Adult↗
PubMed2001

Evaluation of the Accusport lactate analyser.

It has been suggested that lactate concentrations may provide a guide to an optimal training intensity. However, lactate concentrations established during incremental exercise in the laboratory are not always indicative of what is occurring during constant-load exercise at the same intensity. Ideally, lactate concentrations should be measured during a training session and immediately reported to the athlete to ensure that the athlete is working at the desired intensity. The purpose of this investigation was, therefore, to determine the reliability and validity of a compact, portable lactate analyser (ACCUSPORT; Boeringer Mannheim, Castle Hill, Australia). A total of 224 capillary blood samples were taken from athletes who took part in routine laboratory testing. Seventy-three of these capillary blood samples were analysed in duplicate with the Accusport for determination of intraclass, single-trial reliability. Day-to-day intraclass reliability of the Accusport was assessed by analyzing known concentrations of aqueous lactate solutions on seven consecutive days. The validity of the Accusport analyser was assessed by comparing the 224 capillary blood lactate concentrations determined on the Accusport with the lactate concentration obtained using a MICRO STAT LM3 (Analox Instruments Ltd., London, UK). In addition, lactate parameters derived from the lactate concentrations obtained with the two analysers were compared. The Accusport showed high single-trial intraclass reliability (R = 0.992; Standard Error of Measurement [SE(M)] = 0.3 mmol x l(-1); n = 73) and high day-to-day intraclass reliability (R = 0.993; SE(M) = 0.4 mmol x l(-1); n = 42). Despite a strong correlation between blood lactate concentrations obtained on the two analysers (r = 0.96; n = 224) the limits of agreement were + 1.9 to - 2.2 mmol x l(-1). Although the mean values for power output, HR and lactate concentration associated with the lactate parameters were not significantly different when determined on the Accusport or Micro Stat, some individuals did record large differences between analysis methods. In summary, the results of this investigation have shown that lactate concentrations can be reliably determined within a single trial and from day-to-day using the Accusport analyser. However, for some athletes, it is not valid to compare lactate concentrations or lactate parameters determined on the Accusport with those determined using the Micro Stat LM3 lactate analyser.

Adult↗
PubMed2001

The effect of three different warm-up intensities on kayak ergometer performance.

PURPOSE: The purpose of this study was to investigate the influence of warm-up (WU) intensity on supramaximal kayak ergometer performance. METHODS: In the initial testing session, eight institute of sport kayak squad members performed a graded exercise test for determination of VO2max and lactate (La) parameters. In a random, counterbalanced order, subjects subsequently performed WU for 15-min at either their aerobic threshold (W1), their anaerobic threshold (W3), or mid-way between their aerobic threshold and anaerobic threshold (W2). A 5-min passive rest period and then a 2-min, all-out kayak ergometer test followed the WU. RESULTS: For the three different WU conditions, no significant differences were observed for average power, peak VO2, total VO2, total VCO2, or accumulated oxygen deficit (AOD) during the 2-min test. However, when compared with W3, differences in average power approached significance after both W1 (P = 0.09) and W2 (P = 0.10). Furthermore, when compared with W3, average power during the first half of the 2-min test was significantly greater after W2 (P < 0.05) and approached significance after W1 (P = 0.06). After each WU period, there was a significant difference in blood pH (W1>W2>W3; P < 0.05) and blood [La] (W1<W2<W3; P < 0.05). Despite the significantly different metabolic acidemia after each WU condition, there were no significant differences in the VO2 responses to the 2-min test. However, the greater metabolic acidemia after W3 was associated with impaired 2-min kayak ergometer performance. CONCLUSIONS: It was concluded, that although a degree of metabolic acidemia may be necessary to speed O2 kinetics, if the WU is too intense, the associated metabolic acidemia may impair supramaximal performance by reducing the anaerobic energy contribution and/or interfering with muscle contractile processes.

Adolescent↗
PubMed2001

Nonoverlapping clusters: approximate distribution and application to molecular biology.

An approach is developed for the screening of genomic sequence data to identify gene regulatory regions. This approach is based on deciding if putative transcription factor binding sites are clustered together to a greater extent than one would expect by chance. Given n events occurring on an interval of width L (L base pairs), an r:w cluster is defined as r + 1 consecutive events all contained within a window of length wL. Accurate and easily computable approximations are derived for the distribution of the number of nonoverlapping r:w clusters under the model that the positions of the n events have a uniform distribution. Simulations demonstrate that these approximations have greater accuracy than existing methods. The approximation is applied to detect erythroid-specific regulatory regions in genomic DNA sequences, first in an artificial case where r is specified a priori and then as part of an exploratory approach.

Binding Sites↗
PubMed2000

Effects of agitation level on the adsorption, desorption, and activities on cotton fabrics of full length and core domains of EGV (Humicola insolens) and CenA (Cellulomonas fimi).

The activities (at pH 7 and 50 degrees C) of purified EGV (Humicola insolens) and CenA (Cellulomonas fimi) were determined on cotton fabrics at high and low levels of mechanical agitation. Similar activity measurements were also made by using the core domains of these cellulases. Activity experiments suggested that the presence of cellulose binding domains (CBDs) is not essential for cellulase performance in the textile processes, where high levels of mechanical agitation are applied. The binding reversibilities of these cellulases and their cores were studied by dilution of the treatment liquor after equilibrium adsorption. EGV showed low percentage of adsorption under both levels of agitation. It was observed that the adsorption/desorption processes of cellulases are enhanced by higher mechanical agitation levels and that the binding of cellulase with CBD of family I (EGV) is more reversible than that of CBD of the cellulase of family II (CenA).

Journal Article↗
PubMed2000

Physiological predictors of flat-water kayak performance in women.

This study was conducted to investigate the relationship between selected physiological variables and 500-m flat-water kayak (K500) performance. Nine female, high-performance kayak paddlers, mean (SD) age 23 (5) years, participated in this investigation. Testing was conducted over 6 days and included anthropometric measurements (height, body mass and skinfolds), an incremental test to determine both peak VO2 and the "anaerobic threshold" (Th(an)), and a 2-min, all-out test to calculate accumulated oxygen deficit (AOD). Blood lactate concentrations were measured during the incremental test and at the completion of both tests. Subjects also completed a K500 race under competition conditions. K500 time was significantly correlated with both peak VO2 (r = -0.82, P < 0.05) and the power output achieved at the end of the incremental test (r = -0.75, P < 0.05). However, the variable most strongly correlated with K500 time was Th(an) (r = -0.89, P < 0.05). A stepwise multiple regression, for which r = 0.95 and the standard error of estimate = 1.6 s, yielded the following equation: K500time(s) = 160.6-0.154 x AOD x kg(-1) - 0.250 x Th(an). In conclusion, the results of this study have demonstrated that although K500 performance is a predominantly aerobic activity, it does require a large anaerobic contribution. The importance of both the aerobic and anaerobic energy systems is reflected by the K500 time being best predicted by a linear combination of Th(an) and AOD x kg(-1). This suggests the need to develop and implement training programmes that develop optimally both of these physiological attributes. Further research is required to elucidate the most effective means by which to develop both the aerobic and anaerobic energy systems.

Adult↗
PubMed2000

Relationship between plasma lactate parameters and muscle characteristics in female cyclists.

PURPOSE: In a previous study, we showed that when six different plasma lactate parameters (LPs) were compared, the LP determined by the Dmax method was the best predictor of 1-h cycling performance in women. The present study extended these findings to determine whether or not the relationship between the following six LPs and endurance performance could be explained by their relationship with muscle fiber characteristics: 1) lactate threshold (LT; the power output at which plasma lactate concentration begins to increase above the resting level during an incremental exercise test), 2) LT1 (the power output at which plasma lactate increases by 1 mmol x L(-1) or more), 3) LT(D) (the lactate threshold calculated by the Dmax method), 4) LT(MOD) (the lactate threshold calculated by a modified Dmax method), 5) L4 (the power output at which plasma lactate reaches a concentration of 4 mmol x L(-1)), and 6) LT(LOG) (the power output at which plasma lactate concentration begins to increase when the log([La-]) is plotted against the log(power output)). METHODS: Twelve trained female cyclists (27.3 +/- 5.4 yr) first completed an incremental cycle test to determine both their LPs and peak VO2. One week later, endurance performance was assessed as the average absolute power output maintained during a 1-h endurance test (OHT). Resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, 2-oxoglutarate dehydrogenase (OGDH) activity, and phosphofructokinase (PFK) activity. RESULTS: OHT performance was more strongly correlated with all LPs (r = 0.71-0.89, P < 0.05) than with peak VO2 (L x min(-1), r = 0.65, P < 0.05). OGDH activity, PFK activity, and the percentage of Type I fibers were not related to peak VO2, any of the LPs, or OHT performance. The diameter of the Type II fibers, however, was negatively related to OHT performance (r = -0.77, P < 0.01) and to four of the LPs (r = -59 to -0.86, P < 0.001). CONCLUSIONS: These correlations, which indicate that large Type II fibers may impair endurance performance, may be the result of greater production and/or reduced removal of lactate from the larger, glycolytic Type II fibers. LPs most strongly correlated with Type II fiber diameter were also most strongly correlated with OHT performance.

Adult↗
PubMed1999

The effects of strength training on endurance performance and muscle characteristics.

PURPOSE: The purpose of this study was to determine the effects of resistance training on endurance performance and selected muscle characteristics of female cyclists. METHODS: Twenty-one endurance-trained, female cyclists, aged 18-42 yr, were randomly assigned to either a resistance training (RT; N = 14) or a control group (CON; N = 7). Resistance training (2X x wk(-1)) consisted of five sets to failure (2-8 RM) of parallel squats for 12 wk. Before and immediately after the resistance-training period, all subjects completed an incremental cycle test to allow determination of both their lactate threshold (LT) and peak oxygen consumption VO2). In addition, endurance performance was assessed by average power output during a 1-h cycle test (OHT), and leg strength was measured by recording the subject's one repetition maximum (1 RM) concentric squat. Before and after the 12-wk training program, resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, and the activities of 2-oxoglutarate dehydrogenase and phosphofructokinase. RESULTS: After the resistance training program, there was a significant increase in 1 RM concentric squat strength for RT (35.9%) but not for CON (3.7%) (P < 0.05). However, there were no significant changes in OHT performance, LT, VO2, muscle fiber characteristics, or enzyme activities in either group (P > 0.05). CONCLUSION: The present data suggest that increased leg strength does not improve cycle endurance performance in endurance-trained, female cyclists.

Adolescent↗
PubMed1999

Stages of change for increasing fruit and vegetable consumption among adults and young adults participating in the national 5-a-Day for Better Health community studies.

Higher fruit and vegetable consumption is associated with a reduced risk of certain cancers and chronic diseases. The 5-a-Day for Better Health community studies are evaluating population-based strategies to achieving dietary behavior change using the stages-of-change model and associated theories. The authors present baseline comparisons of stages of change for fruit and vegetable consumption among adults and young adults in eight study sites representing diverse regions of the United States and diverse populations and settings. Three dominant stages, precontemplation, preparation, and maintenance, were found across sites. Women and those with college degrees were more likely to be in action/maintenance. Fruit and vegetable consumption, self-efficacy, and knowledge of the 5-a-Day recommendation were positively associated with more advanced stages of change in all study sites. The authors discuss the findings in relation to possible limitations of this and other dietary stages-of-change measures and suggest directions for future research.

Adolescent↗
PubMed1999

Observations on medical device design, Part I: Current practice.

Medical devices must be designed and proven to be fit for the purpose that they were intended. Good design practice ensures this fitness for purpose and is reflected in the commercial success of products. This two-part article focuses on current industry design practice and proposes that there are significant benefits to be obtained by defining good design practice: better products and reduced development costs.

Equipment Design↗
PubMed1999

Observations on medical device design, Part II: Good practice.

Current guidance on design is inadequate. This second article in a two-part series presents a framework for good design practice that attempts to improve designers' awareness of manufacturing and validation issues. Seven design tactics, derived from observations of current industry practice and design literature, seek to encourage good practice and achieve safer, more profitable devices.

Equipment Design↗