A novel way of liver preservation improves rat liver viability upon reperfusion

Background/aim： Currently, the liver is cold-preserved at 0-4 ℃ for experimental and clinical purposes. Here, we investigated whether milder hypothermia during the initial phase of the preservation period was beneficial for liver viability upon reperfusion. Methods： In the first set of experiments, rat livers were preserved either conventionally in clinically used histidine-trypthopan-ketoglutarate （HTK） solution （Group A： 45 min and Group B： 24 h） or by slow cooling HTK solution （from 13 ℃ to 3 ℃） during the initial 45 min of preservation （Group C： 24 h）. In the second set of experiments, additional groups of livers were evaluated： Group BB-preservation according to Group B and Group CC-preservation according to Group C. Further, some livers were preserved at 13 ℃ for 24 h. Livers were then reperfused using a blood-free perfusion model. Results： Bile production was approximately 2-fold greater in Group C compared to Group B. Alanine transaminase （ALT） and aspartate transaminase （AST） release into perfusate were 2-3-fold higher in Group B compared to Group C. No significant differences were found in ALT and AST release between Group C and Group A. Livers in Group CC compared to Group BB exhibited significantly lower portal resistance, greater oxygen consumption and bromosulfophthalein excretion into bile and lower lactate dehydrogenase （LDH） release into perfusate. Histological evaluation of tissue sections in Group BB showed parenchymal dystrophy of hepatocytes, while dystrophy ofhepatocytes was absent in Group CC. Livers preserved at 13 ℃ for 24 h exhibited severe ischemic injury Conclusion： These results suggest that the conventional way of liver preservation is not suitable at least for rat livers and that slow cooling of HTK solution during the initial phase of cold storage can improve liver viability during reperfusion.     

The effect of inspiratory muscle fatigue on acid-base status and performance during race-paced middle-distance swimming

The aim of this study was to investigate the effect of pre-induced inspiratory muscle fatigue (IMF) on race-paced swimming and acid-base status. Twenty-one collegiate swimmers performed two discontinuous 400-m race-paced swims on separate days, with (IMF trial) and without (control trial) pre-induced IMF. Swimming characteristics, inspiratory and expiratory mouth pressures, and blood parameters were recorded. IMF and expiratory muscle fatigue (P < 0.05) were evident after both trials and swimming time was slower (P < 0.05) from 150-m following IMF inducement. Pre-induced IMF increased pH before the swim (P < 0.01) and reduced bicarbonate (P < 0.05) and the pressure of carbon dioxide (PCO₂) (P < 0.05). pH (P < 0.05), bicarbonate (P < 0.01) and PCO₂ (P < 0.05) were lower during swimming in the IMF trial. Blood lactate was similar before both trials (P > 0.05) but was higher (P < 0.01) in the IMF trial after swimming. Pre-induced IMF induced respiratory alkalosis, reduced bicarbonate buffering capacity and slowed swimming speed. Pre-induced and propulsion-induced IMF reflected metabolic acidosis arising from dual role breathing and propulsion muscle fatigue.     

Effect on development of proportional reasoning skill of physical experience and cognitive abilities associated with prefrontal lobe activity

The present study tested the hypothesis that maturing prefrontal lobes play a role in the development of proportional reasoning skill because the prefrontal lobes are involved in the inhibition of task‐irrelevant information and the representation of task‐relevant information. The hypothesis that reasoning development is in part dependent upon physical experience was also tested. Students (all males) who failed to solve a diagnostic proportions task were administered several tests of prefrontal lobe functions. The students were then randomly assigned to manipulative or verbal tutoring groups. Both groups received a series of individual testing, tutoring and testing sessions on proportional reasoning. As predicted, performance on the prefrontal lobe tasks (measures of inhibiting ability, planning ability, dissembedding ability, and working memory capacity) significantly predicted performance on proportional reasoning tasks following tutoring. Students' computational skills were not a significant predictor. Also, the manipulative group's proportional reasoning performance was significantly higher than that of the verbal tutoring group. Therefore, the present results provide support for the hypothesis that maturing prefrontal lobes and physical experience play roles in the development of proportional reasoning skill. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 1171–1182, 2000     

Development of Scientific Reasoning in College Biology: Do Two Levels of General Hypothesis‐Testing Skills Exist?

The primary purpose of the present study was to test the hypothesis that two general developmentally based levels of hypothesis‐testing skills exist. The first hypothesized level presumably involves skills associated with testing hypotheses about observable causal agents; the second presumably involves skills associated with testing hypotheses involving unobservable entities. To test this hypothesis, a hypothesis‐testing skills test was developed and administered to a large sample of college students both at the start and at the end of a biology course in which several hypotheses at each level were generated and tested. The predicted positive relationship between level of hypothesis‐testing skill and performance on a transfer problem involving the test of a hypothesis involving unobservable entities was found. The predicted positive relationship between level of hypothesis‐testing skill and course performance was also found. Both theoretical and practical implications of the findings are discussed. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 81–101, 2000     

Stories of the three-legged stool: English, media, drama, from critique to production

The three authors have, between them, extensive experience of teaching English, Drama and Media, as well as teaching teachers in these fields. The article explores the implications of the apparently straightforward proposition that these three related domains, whose histories are so closely entangled, should enjoy parity. The proposition is explored with reference to the historical constitution of these elements of what we currently know as ‘English’; and to three vignettes illustrating work in schools which productively confuses the three domains.     

Motivating students of diverse sociocultural backgrounds to achieveLa motivación al logro de estudiantes de ambientes socioculturales diversosLa motivation à l'accomplissement d'étudiants ayant un passé socioculturel différent

This paper addresses a problem of major importance to educators: the motivation of students of differing sociocultural backgrounds. While the analysis builds on the earlier work of McClelland, the focus is by no means confined to that perspective. Indeed, achievement motivation is essentially redefined and a more comprehensive analysis is attempted in which personality, situation, and situation x personality factors are all concerned. The central thrust of the article, of course, is on what one can change about personality and situations to increase the achievement motivation of students. In this regard, various intervention studies are reviewed and evaluated, and new possibilities are suggested. There is a decided emphasis on the efficiency, practicality, and general appropriateness of concentrating on situations (or contextual) change rather than attempting to change enduring personality patterns.