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Keywords:

  • undergraduate;
  • toxicology;
  • laboratory techniques;
  • experimental design;
  • statistical analysis;
  • peer review process

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

This article describes a 13-week laboratory course called Human Toxicology taught at the University of Otago, New Zealand. This course used a guided inquiry based laboratory coupled with formative assessment and collaborative learning to develop in undergraduate students the skills of problem solving/critical thinking, data interpretation and written discussion of results. The laboratory practices were a guided inquiry based around retinol's ability to potentiate acetaminophen-mediated hepatotoxicity. To induce critical thinking, students were given a choice as to which assay they could use to determine how retinol affected acetaminophen hepatotoxicity. Short summaries were handed in following each assay and formed the bases of the formative assessment. To complete the feedback loop, a summative assessment that consisted of all the graphs and concepts from the short summaries were combined into a manuscript. To give the students exposure to science communication, the manuscript had to be written in accordance to the submission guidelines for Toxicological Sciences. Evaluation of this course was determined by a student questionnaire using a Likert scale and students' responses were very favorable. While the subject matter was toxicological centric, the content could be easily modified to suit another subject matter in biochemistry and molecular biology. © 2012 by The International Union of Biochemistry and Molecular Biology


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The three most important skills for students to gain from their undergraduate education are: (a) problem solving/critical thinking; (b) data interpretation; and (c) oral and written communication of results [1]. Written communication of results involves writing in a format that is suitable for publication in a specific journal and the peer review process: a process that is normally absence in undergraduate science teaching [2–6]. Our goal was to use a guided inquiry based laboratory coupled with formative assessment and collaborative learning to developed these skills in undergraduates students.

Laboratory teaching methods can take many forms based on the input from the student [7]. These range from no inquiry (i.e., cookbook laboratories), to middle level of inquiry (i.e., guided inquiry) to the highest level of inquiry (i.e., open end inquiry). Cookbook laboratories have minimal level of student inquiry because the students robotically follow the protocol with limited cognitive input [8]. Whereas inquiry based laboratories force the students to take a more active role within the laboratory [9, 10]. Inquiry based laboratories range from guided to open inquiry laboratories. In guided based laboratories, the course coordinator determines the scientific question, however, the students have input on experimental design, data collection, and analysis. In contrast, in open inquiry laboratories, there is minimal input from the teacher whereas the students have input on the experimental question, design, data collection, analysis, and data publication [9]. In open inquiry laboratories, the outcome of the experiment is not known and often occurs when the undergraduate students are assigned to a research laboratory [9]. The advantage of open inquiry laboratories is that ‘science is taught as science is practiced’ [11]. However, open inquiry laboratories have been criticized [12, 13], as it is unreasonable to expect an undergraduate student to go straight from a cookbook laboratory to an open inquiry laboratory. Here we describe a guided inquiry laboratory where the experimental question was set (i.e., does retinol modify acetaminophen toxicity?), but students had input into experimental design, data collection, and analysis. It was hoped that the students would develop skills that would then help them when they entered an open inquiry laboratory.

Guidance was provided to students via formative assessment. Formative assessments are designed to gauge how well students are learning and to provide feedback to students so that they can learn from their mistakes [14–16]. These assessments normally are low weighted (2%) frequent assessments. The advantage of this form of assessment is that students are not penalized for mistakes and have been shown to facilitate learning [14–16].

In line with Science for All Americans, Project 2061, science teaching should involve students working in a collaborative manner [17]. Science is not done alone, but in collaboration and a very important skill that undergraduates should learn is the ability to work with others. Collaborative learning, as defined by Tanner et al., (2003) is where students worked in small groups (n = 2) with the same learning goal and the resulting mark is awarded to both students [18]. The advantage of collaborative learning is that it increases the grade obtained by both students [19, 20]. Collaborative learning was also a component of this study, as students worked in pairs to complete the experiment and all assessments. Furthermore, all results obtained from the groups were combined into one set of class data. This meant that the students could compare their results to others and was an indirect way to check that their experimental technique was correct.

COURSE AND STUDENT INFORMATION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The Human Toxicology (PHAL306) course at the University of Otago, New Zealand is restricted to third year science majors that have taken two pharmacology courses in their second year at university. Note that the Bachelor of Science degree in New Zealand has a duration of three years. The aim of this course is to introduce students to the diverse discipline of toxicology. Principles and concepts are taught by focusing on the mechanisms underlying the toxic effect of a wide variety of chemicals and environmental pollutants. Student numbers fluctuate each year, but the class size is normally between 40–50 students. In 2011, there were 41 students enrolled in this class (age 22 ± 2 years (mean ± SD) with a female:male ratio of 1.7:1. The course ran for 13 weeks and consisted of 23 one hour lectures and six, 3 hour laboratories. Note that only the laboratory component will be described here.

SCIENCE BEHIND THE LABORATORY

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The practical sessions focused on investigating the underlying mechanism behind the ability of retinol to increase acetaminophen-mediated hepatotoxicity. The rationale for choosing this drug interaction is that both retinol and acetaminophen are commonly used in New Zealand. Furthermore, the rationale for using acetaminophen is its metabolic pathway (Fig. 1), which uses different classes of drug metabolizing enzymes. The background knowledge was taught in a lecture and cookbook format the year before (PHAL211: Introductory to Pharmacology). In this course, the concept of inducer (a drug that increases the activity of a enzyme that metabolizes a drug), inhibitor (a drug that inhibits the activity of a enzyme that metabolizes a drug) and substrate (a drug that is metabolized by the enzyme) was introduced. Students in this course also had a session on the ethics of animal use. Furthermore, in third year additional concepts such as co-factors (a compound that is required for a drug to be metabolized) were introduced to enable students to use this information and apply it to a novel problem.

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Figure 1. Metabolic pathway of acetaminophen and the possible ways in which retinol could induce acetaminophen hepatotoxicity At therapeutic doses, acetaminophen undergoes glucuronidation by the enzyme uridine diphosphate-glucuronosyltransferase (UDPGT) and its cofactor uridine diphosphosphoglucuronic acid (UDPGA) and is excreted safely. In addition, acetaminophen can be metabolized by CYP2E1 and CYP3A enzymes to the toxic metabolite, N-acetyl p-benzoquinoneimine (NAPQI). If there is sufficient level of glutathione and the enzyme glutathione-S-transferase (GST) available, NAPQI undergoes conjugation and is excreted safely. In theory, retinol could potentiate acetaminophen-induced hepatotoxicity by interfering with five parts of the acetaminophen's metabolic pathway. First, retinol could act as an inducer of CYP2E1 and/or CYP3A thereby increasing the production of the toxic NAPQI (Pathway 1 on Fig. 1). Second, retinol could act as an inhibitor of GST and thereby reducing NAPQI metabolism (Pathway 2 on Fig. 1). Third, retinol could deplete the levels of glutathione and decrease NAPQI metabolism (Pathway 3 on Fig. 1). Fourth, retinol could act as an inhibitor of UDPGT, thereby reducing the metabolism of acetaminophen via this pathway and resulting in more acetaminophen being metabolized to NAPQI (Pathway 4 on Fig. 1). Fifth, retinol could deplete the levels of UDPGA and in a similar manner as stated for an inhibitor of UDPGT and thereby result in a higher concentration of NAPQI being present (Pathway 5 on Fig. 1). Lastly, it is possible that a combination of the above mention pathways may contribute to the retinol's potential of acetaminophen-induced hepatotoxicity.

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COURSE OBJECTIVES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The objectives of this course were to develop skills in hypothesis testing, experimental design, laboratory technique, statistical analysis, paper preparation, as well as to gain insight into the peer review process. This was achieved by the following: first, to develop skills in hypothesis testing and experimental design, students were given the choice as to which experiment they wanted to perform to determine the underlying mechanisms behind the ability of retinol to increase acetaminophen hepatotoxicity. Furthermore, within each experiment, they had a choice as to which samples to run. The students had to explain their choice of samples run. Third, the students had to combine all of the results from the experiments that were run over several weeks into a coherent manuscript. This was done so that students understood that scientific insight does not result from one experiment performed in one afternoon, but comes about by several experiments done over many months or more likely over many years. Lastly, the manuscript was marked in a manner that mimicked the peer review process so that students could experience the publication process.

LABORATORY SESSIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

PHAL306 is a 13-week course (Table I). The first six weeks involved practicals that were carried out in the teaching laboratory. Two weeks (Weeks 7 and 10) were manuscript work sessions so that the students could have access to computer programmes and have time to meet with their collaborator to work on their manuscript. Two weeks were mid semester break (Weeks 8 and 9). The manuscript was submitted on Week 11 and returned to the student's on Week 12. The students had a week to respond to reviewer's comments (refer to section 5). The first (introduction session) and second practical (does retinol alter acetaminophen-hepatotoxicity?) were mandatory, but the other four practicals were not.

Table I. Practical timetable
WeekPractical session
1Laboratory Introduction/Statistics Tutorial
2Does retinol alter paracetamol-induced hepatotoxicity?
3CYP3A or CYP2E1
4UDPGA OR GSH
5CYP3A or CYP2E1
6UDPGA OR GSH
7Manuscript work session
8Mid semester break
9Mid semester break
10Manuscript work session
11Manuscript due
12Manuscript returned
13Revised manuscript due

Laboratory Session 1: Introduction Session

At the introduction session, the students were informed about the assessment process (refer to section 4) and given the laboratory manual. Within the laboratory manual was a list of references that students were told they may find useful for the summaries and the manuscript (Table II).

Table II. List of background references
Review articleG. Farrell (1994) Paracetamol-induced hepatotoxicity. In: Farrell G (ed). Drug-induced liver diseases, Churchill Livingstone: New York, pp 205–224.
General TextbookA. Parkinson (1996) Biotransformation of Xenobiotics. In: Klaassen CD (ed). Cassarett and Doull's Toxicology. McGraw Hill: New York, pp 113–186.
Specific research articlesM. Murray, E. Cantril, R. Martini, G. C. Farrell (1991) Increased expression of cytochrome P450IIIA2 in male rat liver after dietary vitamin A supplementation Arch. Biochem. Biophys. 286, 618–624.
B. J. Bray, R. J. Rosengren (2001) Retinol potentiates acetaminophen-induced hepatotoxicity in the mouse: Mechanistic studies, Toxicol. Appl. Pharmacol. 173, 129–136.
B. J. Bray, M. G. Goodin, R. E. Inder, R. J. Rosengren (2001) The effect of retinol on hepatic and renal drug metabolising enzymes. Food Chem. Toxicol. 39, 1–9.
A. E. D. El Sisi, P. Hall, W. W. Sim, D. L. Earnest, I. G. Sipes (1993) Characterization of vitamin A potentiation of carbon tetrachloride-induced liver injury, Toxicol. Appl. Pharmacol. 119, 280–288.
D. Badger, J. Kraner, D. Fraser, N. Hoglen, J. Halpert, I. G. Sipes (1998) Reduction of thyroid hormone may participate in the modulation of cytochromes P4502C11 and 3A2 by retinol, Life Sci. 63, PL367–372.
M. J. Rowling, M. H. McMullen, K. C. Schalinske (2002) Vitamin A and its derivatives induce hepatic glycine N-methyltransferase and hypomethylation of DNA in rats, J. Nutr. 132, 365–369.
D. A. Badger, J. M. Sauer, N. C. Hoglen, C. S. Jolley, I. G. Sipes (1996) The role of inflammatory cells and cytochrome P450 in the potentiation of CCl4-induced liver injury by a single dose of retinol. Toxicol. Appl. Pharmacol. 141, 507–519.

Practical 2: Does Retinol Alter Acetaminophen-Induced Hepatotoxicity?

This laboratory session was designed to define the research question and provide evidence that retinol does modify acetaminophen-induced liver toxicity. The students measured plasma alanine aminotransferase (ALT), a common biochemical indicator of liver damage obtained from the following groups of treated rats: (1) untreated; (2) acetaminophen (1 g/kg, 24 hrs prior to euthanasia); (3) retinol (75 mg/kg/d, oral gavage for 4 days and acetaminophen's vehicle, ip 24 hrs prior to euthanasia); (4) acetaminophen + retinol (75 mg/kg/d, oral gavage for 4 days and acetaminophen, ip 24 hrs prior to euthanasia); and (5) CCl4 (100 μl/kg). The students were informed that CCl4 was used as a positive control. All treatments, dissections, and tissue preparation were preformed by the teaching laboratory staff. All experiments were approved by the Animal Ethics Committee at the University of Otago which evaluates the use of animals for both teaching and research. A good student who followed the protocol for the ALT assay would have produced result as shown in Fig. 2. Students were told to use an ANOVA and the Dunnett post-hoc test to determine if there is significant difference between any of the groups and untreated. In addition, they were told that if they require more information regarding the differences between treatment groups (i.e., acetaminophen and retinol + acetaminophen) then the post-hoc test to use was the Student-Newman.

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Figure 2. Example of mean class data for the ALT assay illustrating hepatotoxicity resulting from retinol and acetaminophen (APAP) administration in rats. Rats were treated as follows: (1) untreated; (2) acetaminophen (1 g/kg, 24 hr prior to euthanasia); (3) retinol (75 mg/kg/d, oral gavage for 4 days and acetaminophen's vehicle, ip 24 hr prior to euthanasia); (4) acetaminophen + retinol (75 mg/kg/d, oral gavage for 4 days and acetaminophen, ip 24 hr prior to euthanasia); and (5) CCl4 (100 μL/kg, ip). Plasma from treated rats was assayed. Statistical analysis was performed with a one-way ANOVA coupled with the post-hoc Student-Newman-Keuls test. *Significantly different from untreated, p < 0.05. #Significantly different from untreated and acetaminophen, p < 0.05. Bars represent the mean ± SEM.

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In the laboratory session, students were also told to examine liver sections stained with hematoxylin and eosin from the treatment groups. Students would have observed that there was a correlation between the increase in plasma ALT activity and the presence of histological damage. That is, there was a lack of liver damage in the histological sections taken from untreated and retinol groups, but slight damage present in the acetaminophen group as indicated by mild centrilobular necrosis, but a lack of hepatocytes swelling. In the retinol + acetaminophen group, extensive centrilobular necrosis was present. Having two independent methods to determine damage teaches students that whilst the ALT assay will determine damage, it provides no indication of location and damage type. In contrast, histological techniques allows for the determination of location and damage type. The disadvantage of the histological technique is unlike the ALT assay where quantitative data is obtained, the data is descriptive and therefore difficult to be analyzed, without using a rating scale.

The students then needed to determine the mechanism by which retinol modified acetaminophen-mediated hepatotoxicity. To provide guided inquiry, students had the option to answer the following experimental questions: is retinol altering acetaminophen-inducing hepatotoxicity by: (a) inducing CYP3A; (b) inducing CYP2E1; (c) inhibiting GST; (d) depleting the levels of glutathione; (e) inhibiting UDPGT; and/or (f) depleting the levels of UDPGA (Fig. 1). Due to learning, being by nature an evolutionary process, students were given two opportunities to answer each question over the next four laboratory sessions.

Is Retinol's Potentiation of Acetaminophen-Induced Hepatotoxicity Due to Changes in Hepatic CYP3A And/Or CYP2E1 Activity?

Students had a choice to run assays for either CYP3A or CYP2E1 in laboratory sessions 3 and 5. Due to the involvement of both isoforms in the metabolism of acetaminophen to NAPQI [21] students who understood the literature (Table I), would know that previous papers indicated that retinol can alter both CYP2E1 and CYP3A activity in rats [22–25]. Students had a choice of the following samples: untreated, retinol, acetaminophen/retinol, dexamethasone, or CCl4. The laboratory manual clearly states that it is not necessary to run all samples. There is a rationale for running dexamethasone for the CYP3A activity due to it being an inducer of CYP3A, however, there is no reason to run CCl4 for this assay. In contrast, there is a rationale for running CCl4 for the CYP2E1 activity because it is an inhibitor of CYP2E1, but not dexamethasone because it does not affect this enzyme. It was hoped that working out when and when not to use CCl4 and dexamethasone would reinforce in students the concept of inhibitor and inducer of CYP450 enzymes. If students followed the protocol correctly they would have generated the data in Fig. 3. Students were given the same statistical advice as in laboratory session 2.

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Figure 3. Example of mean class for the CYP3A and CYP2E1 assay illustrating the relationship of acetaminophen (APAP), retinol, and acetaminophen + retinol treatment on these enzymes. Microsomes from treated rats were assayed. Statistical analysis was performed with a one-way ANOVA coupled with the post-hoc Student-Newman-Keuls test. *Significantly different from untreated, p < 0.05. Bars represent the mean ± SEM.

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Is Retinol's Potentiation of Acetaminophen-Induced Hepatotoxicity Due to Changes in Hepatic UDPGA/UDPGT and/or GSH/GST?

During the fourth and sixth laboratory sessions, students had the choice to investigate whether retinol alters the catalytic activity of UDPGT or deplete UDPGA levels. Acetaminophen metabolism and the resulting hepatotoxicity was discussed on multiple occasions in lectures and in laboratory introduction sessions, thus students would have learnt that the isozymes that mediates the glucuronidation of acetaminophen is UGT1A1 [26], whilst retinol is mediated by UGT2B7 [27] and therefore it is illogical to run the UDPGT assay. It is logical to run the UDPGA assay because previous literature indicates that retinol is metabolized via conjugation with UDPGA [28] and furthermore a depletion of UDPGA would push the metabolism of acetaminophen through to the toxic NAPQI pathway. For the UDPGA assay, students had a choice of the following samples: untreated, retinol, acetaminophen, retinol/acetaminophen, CCl4, and phenobarbitone. They were told that phenobarbitone is a classic UDPGA depletor and hence a positive control and therefore it is logical to include this. There is no interaction between CCl4 and UDPGA and therefore it is unnecessary to run this sample. Students who followed the protocol would have generated results as shown in Fig. 4. Students were given the same statistical advice as in laboratory session 2. Because of time restraints, a brief tutorial on how the UDPGT assay works was given and “class” data was available on Blackboard.

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Figure 4. Example of mean class data for the UDPGA assay illustrating the relationship of acetaminophen (APAP), retinol, and acetaminophen + retinol treatment on this cofactor. Statistical analysis was performed with a one-way ANOVA coupled with the post-hoc Student-Newman-Keuls test. *Significantly different from untreated, p < 0.05. #Significantly different from acetaminophen, p < 0.05. Bars represent the mean ± SEM.

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Students had the choice to investigate whether retinol alters the catalytic activity of GST or deplete GSH levels during the fourth and sixth laboratory sessions. Retinol-induced changes in either one or a combination of both would limit the metabolism of NAPQI thus resulting in liver damage. Furthermore, students who have read the recommended literature will know that other chemicals that deplete GSH levels have been demonstrated to increase the hepatotoxicity of acetaminophen [29]. Due to the assay being very similar for measuring GST activity and GSH levels, class data was provided for GST assay, however, students still had to analyze the data. Correct statistical analysis of the results would have indicated that retinol did not alter the catalytic activity of GST. For the GSH assay, students had the choice of untreated, retinol, acetaminophen/retinol, CCl4, or diethyl maleate. Students were told that diethyl maleate is a glutathione depletor (i.e., positive control). If students followed the protocol they would have generated the data shown in Fig. 5. Students were given the same statistical advice as in laboratory session 2. The concepts of metabolites, enzymes, and co-factors were routinely discussed in both 2nd and 3rd year pharmacology classes. Thus, even though the abbreviations are similar, no student has done the wrong assay because they confused an enzyme with a cofactor.

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Figure 5. Example of the mean class data for the GSH assay illustrating the relationship of acetaminophen, retinol and acetaminophen + retinol treatment on this cofactor. Liver homogenates from treated rats were assayed. Statistical analysis was performed with a one-way ANOVA coupled with the post-hoc Student-Newman-Keuls test. *Significantly different from untreated, p < 0.05. #Significantly different from acetaminophen, p < 0.05. Bars represent the mean ± SEM.

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ASSESSMENT

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The assessment consisted of several formative assessments (i.e., short summaries) and one summative assessment (i.e., manuscript). The formative assessment consisted of short summaries that were handed in one week after the practical session and were worth 1% of the final grade. These short summaries involved; (1) a publication quality graph or table, (2) statistical analysis of the results, (3) explanation of the results in the context of the literature (4) references listed in the style of Toxicological Science (5) a list of how each person contributed to the experiments and to the writing of the summaries (6) an answer to the whiteboard question. In an attempt to provide good feedback to the students; an essential component of formative assessment [16, 30], an exemplar of a research summary was included in their laboratory manual. The advantage of using exemplars is that it provides clear standard for the marking criteria and aids in learning [30]. To emphasize to students that the summaries were there to induce learning it was written in their laboratory manual ‘Mistakes will be corrected so that students can refer to the old summaries when necessary to help with either lecture material or with future lab summaries and the final manuscript (i.e., we expect you to learn from your mistakes)’. Furthermore, these short summaries were performed in groups of two. Working in a group results in both students providing peer-feedback to each other. Lastly, the marked summaries were handed back within 3 days so that the student could modify the next summary based on the feedback from their previous one (i.e., prompt feedback [16]). Furthermore, these summaries provided a framework in which to write the summative assessment (i.e., the manuscript).

The white board questions that were part of the short summaries were designed to test students' ability in the following categories: (1) basic laboratory math; (2) understanding the principles behind the techniques; (3) understanding lecture material; and (4) applying knowledge to unfamiliar situations. Because of time constraints of a 3-h laboratory, there is not enough time for students to prepare their own chemicals, however, this is an important skill for graduate students and research technicians and therefore to insure that the students understood the math behind making solutions an example of a white board questions included “show a sample calculation for preparing 100 mL of 0.4 mM erythromycin.” To ensure that students knew the principles behind the techniques: questions such as “why can you read yellow samples from a pink standard curve” were included. Reinforcement of lecture material included questions such as “napthol is a hydroxylated form of what compound?” “Draw the structure of X and one other member of the class to which these belong?” It has been shown that frequent testing of knowledge results in consolidation of memory [31, 32].

The above questions fall into the first and second domains of Bloom's taxonomy for cognitive domain [33]. There were also questions designed to test the third level of Bloom's taxonomy of cognitive domain. These questions included: “based on the class results, would you expect retinol to change the efficacy of tamoxifen. Explain your answer”. Students needed to apply their knowledge of tamoxifen and provide rational explanation for their answer.

In their summaries, students were also given an option to write an abstract. This was to ensure that they had an opportunity to receive feedback; however, no students took this option.

The manuscript was a summative assessment and was a high-stakes assignment due to it being worth 22% of the final grade. The manuscript was also there to “complete the feedback loop” [34] and all components (the abstract, graphs, and concepts) from the summaries were included in the manuscript. The advantage of resubmitting work is that it reinforces student learning and provide insight into whether the feedback was utilized by students [35]. Furthermore, the subject of the manuscript was on the mechanism of retinol's potentiation of acetaminophen-induced liver injury. Thus, students were required to argue/present their mechanism based on the experiments they performed. If they did not examine a key metabolic pathway then they were required to support their proposed mechanism with previously published literature.

The manuscript involved presenting the class results from all practicals in a format prepared according to a submission guidelines for Toxicological Sciences (see supplement information). This journal was chosen because it is a specialized toxicological journal and PHAL306 is a toxicology course. Students were told that failure to follow Toxicological Sciences guideline's would result in a 10% deduction in their grade. Furthermore, they were told that the grades for the manuscript would be weighted as follows in order of importance:

  • 1
    Discussion: Must contain a full discussion of the meaning of class results and how these related to previous work published in journal articles.
  • 2
    Introduction: Give a clear and concise introduction.
  • 3
    Results: Provide clear and concise results and follow all journal guidelines for presentation of graphs and tables.
  • 4
    Methods: Provide concise methods and proper references for each assay.
  • 5
    References: Must cite a minimum of 6 journal articles and follow the format of Toxicological Sciences.

Grades were placed into categories that matched those given to authors who submit manuscripts. Therefore the manuscript fell into one of these classifications:

  • 1
    Accepted without revision (90–100% mark given)
  • 2
    Accepted with minor revision (80–89% mark given)
  • 3
    Accepted with major revision (65–79% mark given)
  • 4
    Rejected (50–64% mark given)
  • 5
    Not reviewed (less than 50% mark given)

The manuscripts were returned with one of the following classifications accompanied by reviewer comments. Students had the option to address the reviewer comments (i.e., revise their manuscript). This was not mandatory, but students who chose to revise the manuscript had the opportunity to increase their mark. All of the students resubmitted their manuscript. Students had two weeks to revise their manuscripts. Note that if the manuscript was below 50% (i.e., classification 5), the manuscript was not reviewed. This was to ensure students did not use the opportunity of resubmitting the manuscript as a crutch for submitting a bad first manuscript. Students were instructed to response to the reviewers comments in bullet point format to mimic the peer-reviewed process. Students were also told to mark their changes in their manuscript in red font. The mean manuscript grade awarded in 2011 was 69% ± 12 (SD) with a range of 55–88%.

Unlike previous peer-review teaching methods, the written manuscript generated by the students was a research article and not a review article [4, 6]. The advantage of this is that it more closely mimics the academic world where the majority of articles are research papers and not reviews. A limitation of the course described here is that student peer-review was not employed. In this case, peer-review was done by the teaching assistants and course coordinator. As previously described, having students peer-review each others work provides an appreciation of the delicate nature of writing unemotional reviewer reports, the complexities of peer review [36], and fosters critical thinking [2, 4–6].

EVALUATION OF THE COURSE BY STUDENTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

On the last day of the semester, students were given a questionnaire that used a Likert scale to gauge their attitude towards the course. Overall, students were very positive about their experience with the laboratory (Table III). Seventy-one percent of the class indicated that the ability to choose which assay to perform helped with their understanding of the metabolic pathway of acetaminophen. Similarly, 79% of the class indicated that the written summaries help develop an understanding of how retinol modifies acetaminophen toxicity. Furthermore, 79% of the students indicated that the short summaries aided with writing the manuscript. Lastly, 82% were in favor of the method of assessment used in this class. The percentage of students in favor of the reviewer's comments was 64%. Students were also asked which produced a better learning environment: a single laboratory report handed in after every individual laboratory or a single manuscript handed in at the end of the semester. Seventy-one percentage of the class said that they prefer the single manuscript as opposed to the single laboratory practice. The Likert scale data indicates that the students felt that the teaching methods used were beneficial.

Table III. Student questionnaire responses
Questions1 & 234 & 5
  1. The students had the option to circle 1, 2, 3, 4, 5 with 1 being very helpful and 5 being not at all helpful.

Did the ability to choose which assay to perform, help with understanding of the metabolic pathway  of paracetamol?71%18%11%
Did the 3 short written summaries following the individual laboratories aid with the understanding the interaction between retinol and paracetamol79%7%14%
Did the short written summaries following the individual laboratory aid with writing the manuscript?79%11%11%
Did the chance to address the reviewer's comments (i.e., revise your manuscript) aid with the learning of the laboratory material?64%14%22%
Overall, how effective have you found the PHAL306 method of laboratory report assessment?82%18%0%

Students were also allowed to provide comments free on the laboratory assessment. Three students indicated that the manuscript helped them to understand the laboratory content. One student commented on the limitation of the teaching paradigm in that only one topic is taught. Two students commented that they did all assays because they assumed that they were included for a reason. Two commented that the workload for the summaries was in their opinion too high.

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES

The three most important skills for students to gain are (a) problem solving/critical thinking; (b) interpreting data; and (c) oral and written communication of results [1]. Our goal was to develop a course that aided in the development of these skills using the following teaching methods: guided inquiry based laboratory coupled with formative assessment and collaborative learning.

Critical thinking has been defined as “purposeful, self-regulatory judgment that drives problem-solving and decision-making” [37]. As the course progressed, using the guided inquiry based laboratory teaching model, the results from the experiments began to alter how the students thought about retinol-induced acetaminophen toxicity (i.e., cognitive flexibility). Furthermore, they used these results as a decision-making tool to choose which assay to do next. Last, during their paper writing, they formulated the results into a conceptual framework (or schemata) to describe how retinol modifies acetaminophen toxicity? These higher order cognitive skills are not induced by cookbook form of laboratory work.

The design of the formative assessment allows for the student to develop their skills in interpreting data. Prompt feedback was provided to avoid student misconception. Lastly, the summative assessment was modeled after the peer-reviewed process to give the students an insight into publishing. We believe these teaching paradigms aided in the development of these skills. Furthermore, the students were very receptive to this form of teaching. While the educational content describe here is very toxicological centric, the experimental question and suggested experiments could be modified to suit another topic in biochemistry or molecular biology.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. COURSE AND STUDENT INFORMATION
  5. SCIENCE BEHIND THE LABORATORY
  6. COURSE OBJECTIVES
  7. LABORATORY SESSIONS
  8. ASSESSMENT
  9. EVALUATION OF THE COURSE BY STUDENTS
  10. CONCLUSIONS
  11. REFERENCES
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