title: Enzyme activity down to −100°C

authors: Bragger, J.M.

subjects: Alkaline phosphatise

abstract: The activities of two enzymes, beef liver catalase (EC 1.11.1.6) and calf intestine alkaline phosphatase (EC 3.1.3.1), have been measured down to −97°C and −100°C, respectively. Enzyme activity has not previously been measured at such low temperatures. For catalase, the cryosolvents used were methanol:ethylene glycol:water (70:10:20) and DMSO:ethylene glycol:water (60:20:20). For alkaline phosphatase, methanol:ethylene glycol:water (70:10:20) was used. All of the Arrhenius plots were linear over the whole of the temperature range examined. Since the lowest temperatures at which activity was measured are well below the dynamic transition observed for proteins, the results indicate that the motions which cease below the dynamic transition are not essential for enzyme activity. In all cases the use of cryosolvent led to substantial increases in Arrhenius activation energies, and this imposed practical limitations on the measurement of enzyme activity below −100°C. At even lower temperatures, enzyme activity may be limited by the effect of solvent fluidity on substrate/product diffusion, but overall there is no evidence that any intrinsic enzyme property imposes a lower temperature limit for enzyme activity.

text: Enzyme activity down to −100°C The activities of two enzymes, beef liver catalase (EC 1.11.1.6) and calf intestine alkaline phosphatase (EC 3.1.3.1), have been measured down to −97°C and −100°C, respectively. Enzyme activity has not previously been measured at such low temperatures. For catalase, the cryosolvents used were methanol:ethylene glycol:water (70:10:20) and DMSO:ethylene glycol:water (60:20:20). For alkaline phosphatase, methanol:ethylene glycol:water (70:10:20) was used. All of the Arrhenius plots were linear over the whole of the temperature range examined. Since the lowest temperatures at which activity was measured are well below the dynamic transition observed for proteins, the results indicate that the motions which cease below the dynamic transition are not essential for enzyme activity. In all cases the use of cryosolvent led to substantial increases in Arrhenius activation energies, and this imposed practical limitations on the measurement of enzyme activity below −100°C. At even lower temperatures, enzyme activity may be limited by the effect of solvent fluidity on substrate/product diffusion, but overall there is no evidence that any intrinsic enzyme property imposes a lower temperature limit for enzyme activity.

year: 2000

title: Improving road safety and health: Understandng kava's impact on driver fitness.

authors: Aporosa, S. 'Apo'

abstract: Kava (Piper methysticum) is a traditional and culturally significant Pacific Island beverage that produces a soporific relaxant effect. Kava’s psychopharmacological action is similar to the anti-anxiety drug Benzodiazepine. Traditional users often consume the kava drink at volumes as much as 30 times greater than pharmacologically recommended doses. Prompted by concerns regarding driver impairment post kava drinking, a study was undertaken replicating traditional kava sessions in terms of duration and kava consumption, to investigate the effects of kava on driving capability.
Kava consumers (n=20) attended two six-hour kava sessions, each participant drinking an average 3.52 litres of kava. A non-kava consuming control group (n=20) was included in the study. At baseline all the participants completed computerised industry standard driver safety assessment tests (Vienna Test System: Traffic WAFA Alertness and WAFG Divided Attention) to measure reaction time, perception and attention. Re-testing was conducted at hourly intervals over the six-hour period. Pre/post analysis compared person to person and between groups change. Statistical modeling was based on ANOVA, independent t-tests and Bayesian analysis.
Data analysis indicated no statistically significant (p<0.05) difference between reaction time and divided attention, both within individuals and between groups, at any measurement point over the six-hour testing period. The mean reaction time and divided attention time at the baseline measurement was 249.95msec (milliseconds) and 583.58msec respectively. The control and active group mean reaction time at the final test was 256.70msec and 271.8msec respectively. The mean divided attention times for the control and active groups at the final test were 499.75msec and 568.32msec.
Kava at traditional consumption volumes was not correlated to response latency or impairment on perception and attention tasks, when measured using authoritative driver assessment tests. From this it could be inferred that kava use at traditionally influenced consumption volumes does not compromise driver safety. However, it can be argued that current industry standard accepted cognitive measures of driver safety, assess impairment from the use of euphoric and hallucinogenic drug substances (such as alcohol and marijuana), and fail to account for kava’s unique form of ‘intoxication’. Further research beyond the assessment of these two cognitive functions is, it seems, desirable to better understand if kava has any effect on driver ability.
The study was funded by the Health Research Council of New Zealand (16/462) and the University of Waikato, and the test battery was generously donated by Vienna Tests Systems, Germany.

text: Improving road safety and health: Understandng kava's impact on driver fitness. Kava (Piper methysticum) is a traditional and culturally significant Pacific Island beverage that produces a soporific relaxant effect. Kava’s psychopharmacological action is similar to the anti-anxiety drug Benzodiazepine. Traditional users often consume the kava drink at volumes as much as 30 times greater than pharmacologically recommended doses. Prompted by concerns regarding driver impairment post kava drinking, a study was undertaken replicating traditional kava sessions in terms of duration and kava consumption, to investigate the effects of kava on driving capability.
Kava consumers (n=20) attended two six-hour kava sessions, each participant drinking an average 3.52 litres of kava. A non-kava consuming control group (n=20) was included in the study. At baseline all the participants completed computerised industry standard driver safety assessment tests (Vienna Test System: Traffic WAFA Alertness and WAFG Divided Attention) to measure reaction time, perception and attention. Re-testing was conducted at hourly intervals over the six-hour period. Pre/post analysis compared person to person and between groups change. Statistical modeling was based on ANOVA, independent t-tests and Bayesian analysis.
Data analysis indicated no statistically significant (p<0.05) difference between reaction time and divided attention, both within individuals and between groups, at any measurement point over the six-hour testing period. The mean reaction time and divided attention time at the baseline measurement was 249.95msec (milliseconds) and 583.58msec respectively. The control and active group mean reaction time at the final test was 256.70msec and 271.8msec respectively. The mean divided attention times for the control and active groups at the final test were 499.75msec and 568.32msec.
Kava at traditional consumption volumes was not correlated to response latency or impairment on perception and attention tasks, when measured using authoritative driver assessment tests. From this it could be inferred that kava use at traditionally influenced consumption volumes does not compromise driver safety. However, it can be argued that current industry standard accepted cognitive measures of driver safety, assess impairment from the use of euphoric and hallucinogenic drug substances (such as alcohol and marijuana), and fail to account for kava’s unique form of ‘intoxication’. Further research beyond the assessment of these two cognitive functions is, it seems, desirable to better understand if kava has any effect on driver ability.
The study was funded by the Health Research Council of New Zealand (16/462) and the University of Waikato, and the test battery was generously donated by Vienna Tests Systems, Germany.

year: 2018

title: Bucking the Trends: Increasing retention rates of Māori students enrolled in Faculty of Arts and Social Sciences courses at the University of Waikato

authors: Levy, Michelle Patricia

subjects: Maori

abstract: Reports on the success of the Faculty of Arts and Social Sciences at the University of Waikato’s monitoring and support for Maori students initiative. The aim of the initative was to implement a support system in the FASS that would enhance retention rates for
Māori students in the Faculty.

text: Bucking the Trends: Increasing retention rates of Māori students enrolled in Faculty of Arts and Social Sciences courses at the University of Waikato Reports on the success of the Faculty of Arts and Social Sciences at the University of Waikato’s monitoring and support for Maori students initiative. The aim of the initative was to implement a support system in the FASS that would enhance retention rates for
Māori students in the Faculty.

year: 2003