Effects of a sudden change in curriculum delivery mode in postgraduate clinical studies, following the COVID-19 pandemic.

OBJECTIVE: To examine the effect of a change in the delivery mode of clinical neurology, a postgraduate subject at Macquarie University, following COVID-19 restrictions on face-to-face teaching. METHODS: Participants were master of chiropractic students (n = 212) who completed 2019 or 2020 clinical neurology. The main outcome measure was a comparison of objective structured clinical examination (OSCE) marks between the 2019 and 2020 cohorts. The 2019 group underwent traditional, face-to-face learning, whereas the 2020 group were taught and examined remotely in session 1 but returned to campus in session 2. Descriptive analyses, between-group differences, and generalized linear models were performed. RESULTS: Means for OSCE marks between the 2 groups were higher in the 2020 group in session 1 (p < .001). However, when students returned to campus in session 2, the means were significantly lower in the 2020 group compared with the 2019 group (p < .001). Generalized linear regression indicated that the web-based mode of delivery in 2020 might have had a significant impact on OSCE marks compared with their 2019 counterparts (p < .001). CONCLUSION: The sudden change in the mode of delivery from face-to-face to remote learning and the change in testing methods in response to the global COVID-19 pandemic had a significant effect on clinical neurology student performance scores. The OSCE marks in the 2020 cohort for session 1 were higher than those in 2019. However, when the 2020 cohort returned to on-campus tutorials in session 2, their marks were lower than those of their 2019 counterparts.

Chiropractic student diagnosis and management of headache disorders: A survey examining self-perceived preparedness and clinical proficiency.

OBJECTIVE: To explore the self-perceived preparedness and clinical proficiency in headache diagnosis and management of Australian chiropractic students in senior years of study. METHODS: Australian chiropractic students in the 4th (n = 134) and 5th year (n = 122) of 2 chiropractic university programs were invited to participate in an online cross-sectional survey. Descriptive analyses were conducted for all variables. Post hoc analyses were performed using simple linear regression to evaluate the relationship between self-perceived preparedness and correctness of headache diagnosis and management scores. RESULTS: Australian chiropractic students in senior years demonstrated moderate overall levels of self-perceived preparedness and proficiency in their ability to diagnose and manage headache disorders. Final-year students had a slightly higher self-perceived preparedness and proficiency in headache diagnosis and management compared to those students in the 4th year of study. There was no relationship between self-perceived preparedness and correctness of headache diagnosis and management for either 4th- or 5th-year chiropractic students. CONCLUSION: Our findings suggest that there may be gaps in graduate chiropractic student confidence and proficiency in headache diagnosis and management. These findings call for further research to explore graduate chiropractic student preparedness and proficiency in the diagnosis and management of headache disorders.

Team-based learning in neuroanatomy.

OBJECTIVE: Team-based learning (TBL) is an active learning method in which student teams participate in individual work, teamwork, and the application of learned concepts to problem solving. It has been widely adopted in the education of health professions. The aim of this study was to assess whether TBL in tutorials would be beneficial to students' assessed knowledge and subjective sense of satisfaction as compared to traditional modes of teaching. METHODS: In 2018, TBL was introduced into the tutorials of a clinically oriented undergraduate course of neuroanatomy, and its benefits in improving student grades and satisfaction were assessed. The Welch 2 sample t test was used for group differences in continuous variables, and Pearson's χ2 test with Yates' continuity correction was used for group differences in dichotomous variables. Linear modeling was used to look for group differences while adjusting for significant baseline characteristics. RESULTS: Our study found that in comparison to more traditionally delivered teaching, TBL did not improve grades or alter overall satisfaction. A post hoc pairwise comparison of satisfaction among lectures, tutorials, and practical classes showed that students appeared to be most dissatisfied with the TBL. CONCLUSION: Analysis of our methods, results, student comments, and the literature indicate that the length of the tutorials, at 1 hour, was too short to conduct TBL to the standards required. In addition, there is an imperative to persist in preparing students for a different knowledge-transfer paradigm, and it takes a few iterations to improve the approach and application of this method of teaching.

Exercise and Insulin Resistance.

In insulin resistance, alterations occur in the signalling pathways that modulate glucose uptake into cells, especially skeletal muscle cells, resulting in impaired glucose homeostasis. Glucose uptake into cells is controlled by a number of pathways, some of which are insulin-dependent. During exercise glucose uptake can occur independently of insulin regulation, and hence research into the effects of exercise on insulin resistance must be clearly defined to reflect whether glucose uptake has been enhanced as a result of the utilisation of these insulin-independent pathways, or whether exercise directly affects insulin resistance in cells. Research into the benefits of exercise for insulin resistance is also problematic in the need to clarify whether it is the exercise itself, or the visceral fat/weight loss that has resulted from the exercise, that has led to improved insulin sensitivity. The research presents a promising picture for the benefits of exercise in insulin resistance.

Effects of Nonpharmaceutical Treatments on Symptom Management in Adults With Mild or Moderate Multiple Sclerosis: A Meta-analysis.

OBJECTIVE: The aim of this study was to conduct a meta-analysis of clinical trials on the effect of nonpharmaceutical treatments on outcomes for multiple sclerosis (MS). METHODS: The CINAHL, Mantis, Medline, PEDro, PubMed, and Scopus databases were searched. Final papers meeting inclusion criteria were scored with the Physiotherapy Evidence Database for quality and included in a meta-analysis. Forty papers in the meta-analysis totaled 1673 participants. The interventions were grouped into 6 subcategories: physical activity, technology, rehabilitation, alternative, resistance training, and psychological. RESULTS: The combined effect of interventions produced a large overall effect size for the outcome fatigue; medium effect sizes for functionality, balance, and quality of life; and no effect on pain or spasticity. Physical activity had the greatest effect, improving fatigue, function, and balance. Rehabilitation and resistance training had a large effect on functionality. Comparatively, psychological approaches had only a small effect on improving quality of life. Sample sizes of included papers tended to be small with large variability in design. Therefore, results should be interpreted cautiously. CONCLUSION: Our results suggest there may be effective nonpharmaceutical treatment options available that can improve the symptoms of fatigue, poor functionality, balance, and quality of life. We found that physical activity, alternative approaches, rehabilitation, and resistance training were effective for improving the management of a number of MS symptoms.

The usefulness of a novel patient management decision aid to improve clinical decision-making skills in final year chiropractic students.

Background: The process of developing patient management plans requires a series of clinical decision-making skills that can take years in practice to develop. For the inexperienced practitioner, providing a logical, systematic patient management framework may assist in clinical scenarios and accelerate their decision-making skill development. The purpose of this study was to assess whether a novel clinical management decision aid would improve the management decision-making of chiropractic students. Methods: A prospective before and after study tracked chiropractic master degree students in their final year of study across a 10-week period from February-May, 2017. Case-based assessments were performed at baseline, after initial exposure to the decision aid, and after repeated exposure over the course of the semester. Outcome measures included the results from the 3 assessments, scored out of 20 by two markers using a standardised marking rubric, then averaged and converted to percentages; and 2 feedback questionnaires, given after initial exposure and at 10 weeks. Results: A total of 75 students (44 males; 31 females) participated in the study. The mean score at baseline was 8.34/20 (41.7%) (95% CI: 7.98, 8.70; SD: 1.56) and after initial exposure was 9.52/20 (47.6%) (95% CI: 9.06, 9.98; SD: 2.02). The mean score after repeated exposure was 15.04/20 (75.2%) (95% CI: 14.46, 15.62; SD: 2.54). From baseline to initial exposure, there was a statistically significant absolute increase in mean score of 1.18/20 (5.9%) (95% CI: 0.6, 1.76; p < 0.0001), or a 2.82/20 (14.1%) relative improvement. From baseline to repeated exposure, there was a statistically significant absolute increase in mean score of 6.7/20 (33.5%) (95% CI: 6.02, 7.38; p < 0.0001), or a 16.06/20 (80.3%) relative improvement. The questionnaire results were also favourable. 56/75 (75%) participants agreed that the decision aid was easy to use and 46/75 (61%) of participants agreed that the decision aid improved their ability to integrate various management techniques. Conclusion: Implementing a clinical management decision aid into the teaching curriculum helped to facilitate the ability of chiropractic students to develop patient management plans.

A collaborative process for a program redesign for education in evidence-based health care.

OBJECTIVE:: We outline the framework of a collaborative process to redesign an existing 5-year health education program, which may prove useful to other similar institutions. The aim was to strengthen evidence-based practice and curriculum alignment. METHODS:: A whole-of-program approach was used to restructure the existing courses into 3 "streams": professional practice, clinical research, and clinical science. The process incorporated a series of facilitated workshops organized by the department director of learning and teaching and the faculty facilitation team, and it was inclusive of all available members of the department, a clinic supervisor, a sessional (casual teaching) staff member, and a recent graduate of the program. RESULTS:: Unit content and assessments were restructured to progress the program learning outcomes from year to year. The undergraduate program was redesigned to create a more logical learning pathway for students. Consolidation of subject topics in the postgraduate program allowed for the development of stand-alone research-only units. CONCLUSION:: The mechanism of curriculum mapping allowed for discussion about the flow of information from year to year and how evidenced knowledge and understanding can be developed. It is necessary that everyone participates and understands the importance of program goals as developed by the process. Because drift in curriculum can occur incrementally over the years, to be effective, the program requires ongoing monitoring and regular collaboration to continue improvements.

Is Pilates an effective rehabilitation tool? A systematic review.

BACKGROUND: Pilates is a system of exercise focusing upon controlled movement, stretching and breathing. Pilates is popular today not only for physical fitness but also for rehabilitation programs. This paper is a review of the literature on the effectiveness of Pilates as a rehabilitation tool in a wide range of conditions in an adult population. METHODS: A systematic literature review was carried out according to the PRISMA guidelines. Electronic databases were searched for cohort studies or randomised controlled trials (RCTs), and inclusion and exclusion criteria were applied. The final RCTs were assessed using the PEDro and CONSORT 2010 checklists. RESULTS: Twenty-three studies, published between 2005 and 2016, met the inclusion criteria. These papers assessed the efficacy of Pilates in the rehabilitation of low back pain, ankylosing spondylitis, multiple sclerosis, post-menopausal osteoporosis, non-structural scoliosis, hypertension and chronic neck pain. Nineteen papers found Pilates to be more effective than the control or comparator group at improving outcomes including pain and disability levels. When assessed using the CONSORT and PEDro scales, the quality of the papers varied, with more falling toward the upper end of the scale. CONCLUSION: The majority of the clinical trials in the last five years into the use of Pilates as a rehabilitation tool have found it to be effective in achieving desired outcomes, particularly in the area of reducing pain and disability. It indicates the need for further research in these many areas, and especially into the benefits of particular Pilates exercises in the rehabilitation of specific conditions.

A cross-sectional study of chiropractic students' research readiness using the Academic Self-Concept Analysis Scale.

OBJECTIVE: The shift toward evidence-based health care has reoriented tertiary clinical education in a way that necessitates and incorporates research. This study assesses the inclination and suitability of chiropractic students for research over a 5-year educational program. METHODS: Research attributes of chiropractic students were assessed in this cross-sectional study using a validated and modified academic self-concept analysis scale. Students in first and final year were assessed in 4 domains: creativity, motivation, self-regulation, and general intellectual ability. Univariable differences were assessed using Welch 2-sample t tests, and multivariable analysis was carried out with multiple linear regression models. RESULTS: The response rate was 71% (n = 165). First- and fifth-year students scored highly on all 4 domains (80% to 96%). Compared to first-year students, fifth-year students rated themselves significantly lower in 3 of the domains: general intellectual abilities (t[126] = -2.01; p = 0.047), motivation (t[115] = -4.82; p < 0.001), and creativity (t[136] = -3.00; p = 0.003). CONCLUSION: Research suitability is high in chiropractic students. Both cohorts scored high in all domains despite the disparity between first and fifth years. First-year students outperformed fifth-year students in 3 domains, indicating a potential decline in the inclination to do research over time. However, unaccounted factors, such as the Dunning-Kruger effect, life changes, and "burnout," may have contributed to these differences. Future studies should include questions about stress, fatigue, clinical orientation, and educational environment to inform the interpretation of findings.

No differences in grades or level of satisfaction in a flipped classroom for neuroanatomy.

OBJECTIVE: The intensive nature of a 5- or 6-week teaching block poses unique problems for adequate delivery of content. This study was designed to compare the delivery of a unit of undergraduate neuroanatomy in a short summer school period, as a traditionally taught unit, with a rendition given in the form of the "Flipped Classroom." The aim was to evaluate the effectiveness of the flipped classroom in the intensive mode classroom. METHODS: The flipped classroom encompassed the same learning outcomes, but students were responsible for covering the content at home in preparation for tutorials that applied their acquired knowledge to higher levels of thinking. The main outcome measures were the final course grades and the level of satisfaction with the course. RESULTS: There were no significant differences between the 2 cohorts in final grades (p = .259), self-rated knowledge (p = .182), or overall satisfaction with the course (p = .892). CONCLUSION: This particular design of the flipped classroom did not add value to the intensive mode experience. It may be that this mode of delivery is ill suited to intensive classes for subjects that carry a lot of content. The use of the flipped classroom requires further research to fully evaluate its value.

The learning style preferences of chiropractic students: A cross-sectional study.

Objective : The aims of our study were to measure the learning style preferences of chiropractic students and to assess whether they differ across the 5 years of chiropractic study. Methods : A total of 407 (41.4% females) full-degree, undergraduate, and postgraduate students enrolled in an Australian chiropractic program agreed to participate in a cross-sectional survey comprised of basic demographic information and the Visual, Aural, Read/Write, Kinesthetic (VARK) questionnaire, which identifies learning preferences on four different subscales: visual, aural, reading/writing, and kinesthetic. Multivariate analysis of variance and the χ(2) test were used to check for differences in continuous (VARK scores) and categorical (VARK category preference) outcome variables. Results : The majority of chiropractic students (56.0%) were found to be multimodal learners. Compared to the other learning styles preferences, kinesthetic learning was preferred by a significantly greater proportion of students (65.4%, p < .001) and received a significantly greater mean VARK score (5.66 ± 2.47, p < .001). Conclusions : To the best of our knowledge, this is the first time chiropractic students have been shown to be largely multimodal learners with a preference for kinesthetic learning. While this knowledge may be beneficial in the structuring of future curricula, more thorough research must be conducted to show any beneficial relationship between learning style preferences and teaching methods.

Intensive mode delivery of a neuroanatomy unit: lower final grades but higher student satisfaction.

In 2011, Macquarie University moved to a three-session academic year which included two 13-week sessions (traditional mode) and one seven-week session (intensive mode). This study was designed to compare the intensive and traditional modes of delivery in a unit of undergraduate neuroanatomy. The new intensive mode neuroanatomy unit provided the same quantity and quality of material to the same standard, delivered by the same teachers and over the same total hours, but in a shorter timeframe. All students enrolled in session 2 (traditional mode) and session 3 (intensive mode) were invited to participate in this study. The main outcome measures were the final course grades and level of satisfaction with the course. Although there was no significant difference between the two cohorts in self-rated level of knowledge (P = 0.148), the traditional mode cohort achieved significantly higher final grades compared to the intensive mode cohort (P = 0.001). Similarly, the distribution of final grades was also different between the two cohorts. The two cohorts were equally satisfied with the unit overall, and with the lectures and tutorials. However, the intensive mode cohort was more satisfied with the laboratory practical classes compared to the traditional mode cohort (P < 0.001). Thus this study demonstrates that in the case of neuroanatomy, which is high in content, when the course is taught to the same standards as exist in the traditional mode of delivery, the students do not do as well even though they enjoy the course equally.

The effect of face-to-face teaching on student knowledge and satisfaction in an undergraduate neuroanatomy course.

The total number of anatomy teaching hours has declined in medical courses worldwide. Conversely, face-to-face teaching in undergraduate neuroanatomy at Macquarie University increased by 50% in 2011. Our aim was to investigate whether this influenced student performance and overall satisfaction with the course. One hundred eighty-one students consented to participate in this study. A questionnaire was administered to rate the course, and final grades from the old and new unit cohorts were compared. The old and new unit cohorts did not differ in their final grades (P = 0.249). However, the new unit cohort rated their knowledge of the material higher compared to the old unit cohort (P = 0.013), and reported higher levels of satisfaction with the course (P < 0.001). In an era in which teaching time for anatomy has been reduced at tertiary institutions, and there is much lamenting of the effect this will have, there is a paucity of literature on whether the decrease really influences neuroanatomical knowledge. This is the first study, to the best of our knowledge, to show that an increase in total face-to-face teaching hours does not improve student grades, but does increase student satisfaction with the course.

Glutamine and α-ketoglutarate as glutamate sources for glutathione synthesis in human erythrocytes.

Glutathione (GSH) is an intracellular antioxidant synthesized from glutamate, cysteine and glycine. The human erythrocyte (red blood cell, RBC) requires a continuous supply of glutamate to prevent the limitation of GSH synthesis in the presence of sufficient cysteine, but the RBC membrane is almost impermeable to glutamate. As optimal GSH synthesis is important in diseases associated with oxidative stress, we compared the rate of synthesis using two potential glutamate substrates, α-ketoglutarate and glutamine. Both substrates traverse the RBC membrane rapidly relative to many other metabolites. In whole RBCs partially depleted of intracellular GSH and glutamate, 10 mm extracellular α-ketoglutarate, but not 10 mm glutamine, significantly increased the rate of GSH synthesis (0.85 ± 0.09 and 0.61 ± 0.18 µmol·(L RBC)(-1) ·min(-1), respectively) compared with 0.52 ± 0.09 µmol·(L RBC)(-1) ·min(-1) for RBCs without an external glutamate source. Mathematical modelling of the situation with 0.8 mm extracellular glutamine returned a rate of glutamate production of 0.36 µmol·(L RBC)(-1) ·min(-1), while the initial rate for 0.8 mM α-ketoglutarate was 0.97 µmol·(L RBC)(-1) ·min(-1). However, with normal plasma concentrations, the calculated rate of GSH synthesis was higher with glutamine than with α-ketoglutarate (0.31 and 0.25 µmol·(L RBC)(-1) ·min(-1), respectively), due to the substantially higher plasma concentration of glutamine. Thus, a potential protocol to maximize the rate of GSH synthesis would be to administer a cysteine precursor plus a source of α-ketoglutarate and/or glutamine.

The effects of long-term storage of human red blood cells on the glutathione synthesis rate and steady-state concentration.

BACKGROUND: Banked red blood cells (RBCs) undergo changes that reduce their viability after transfusion. Dysfunction of the glutathione (GSH) antioxidant system may be implicated. We measured the rate of GSH synthesis in stored RBCs and applied a model of GSH metabolism to identify storage-dependent changes that may affect GSH production. STUDY DESIGN AND METHODS: RBC units (n = 6) in saline-adenine-glucose-mannitol (SAGM) solution were each divided into four transfusion bags and separate treatments were applied: 1) SAGM (control), 2) GSH precursor amino acids, 3) aminoguanidine, and 4) glyoxal. RBCs were sampled during 6 weeks of storage. Rejuvenated RBCs were also analyzed. RESULTS: After 6 weeks, the ATP concentration declined to 50 ± 5.5% (p < 0.05) of that in the fresh RBCs. For control RBCs, the GSH concentration decreased by 27 ± 6.5% (p < 0.05) and the rate of GSH synthesis by 45 ± 8% (p < 0.05). The rate of GSH synthesis in rejuvenated and amino acid-treated RBCs was unchanged after 6 weeks. Modeling identified that the decline in GSH synthesis was due to decreased intracellular substrate concentrations and reduced amino acid transport, secondary to decreased ATP concentration. CONCLUSION: This study has uniquely shown that the glutathione synthesis rate decreased significantly after 6 weeks in stored RBCs. Our results have identified potential opportunities for improvement of banked blood storage.

Glutathione synthesis and turnover in the human erythrocyte: alignment of a model based on detailed enzyme kinetics with experimental data.

The erythrocyte is exposed to reactive oxygen species in the circulation and also to those produced by autoxidation of hemoglobin. Consequently, erythrocytes depend on protection by the antioxidant glutathione. Mathematical models based on realistic kinetic data have provided valuable insights into the regulation of biochemical pathways within the erythrocyte but none have satisfactorily accounted for glutathione metabolism. In the current model, rate equations were derived for the enzyme-catalyzed reactions, and for each equation the nonlinear algebraic relationship between the steady-state kinetic parameters and the unitary rate constants was derived. The model also includes the transport processes that supply the amino acid constituents of glutathione and the export of oxidized glutathione. Values of the kinetic parameters for the individual reactions were measured predominately using isolated enzymes under conditions that differed from the intracellular environment. By comparing the experimental and simulated results, the values of the enzyme-kinetic parameters of the model were refined to yield conformity between model simulations and experimental data. Model output accurately represented the steady-state concentrations of metabolites in erythrocytes suspended in plasma and the changing glutathione concentrations in whole and hemolyzed erythrocytes under specific experimental conditions. Analysis indicated that feedback inhibition of gamma-glutamate-cysteine ligase by glutathione had a limited effect on steady-state glutathione concentrations and was not sufficiently potent to return glutathione concentrations to normal levels in erythrocytes exposed to sustained increases in oxidative load.

Role of N-acetylcysteine and cystine in glutathione synthesis in human erythrocytes.

Glutathione is an intracellular antioxidant that often becomes depleted in pathologies with high oxidative loads. We investigated the provision of cysteine for glutathione synthesis to the human erythrocyte (red blood cell; RBC). Almost all plasma cysteine exists as cystine, its oxidized form. In vitro, extracellular cystine at 1.0 mM sustained glutathione synthesis in glutathione-depleted RBCs, at a rate of 0.206 +/- 0.036 micromol (L RBC)(-1)min(-1) only 20% of the maximum rate obtained with cysteine or N-acetylcysteine. In plasma-free solutions, N-acetylcysteine provides cysteine by intracellular deacetylation but to achieve maximum rates of glutathione synthesis by this process in vivo, plasma N-acetylcysteine concentrations would have to exceed 1.0 mM, which is therapeutically unattainable. (1)H-NMR experiments demonstrated that redox exchange reactions between NAC and cystine produce NAC-cysteine, NAC-NAC and cysteine. Calculations using a mathematical model based on these results showed that plasma concentrations of N-acetylcysteine as low as 100 microM, that are attainable therapeutically, could potentially react with plasma cystine to produce approximately 50 microM cysteine, that is sufficient to produce maximal rates of glutathione synthesis. We conclude that the mechanism of action of therapeutically administered N-acetylcysteine is to reduce plasma cystine to cysteine that then enters the RBC and sustains glutathione synthesis.

Glutathione synthesis by red blood cells in type 2 diabetes mellitus.

Oxidative stress is implicated in the pathogenesis and complications of type 2 diabetes mellitus (NIDDM). Glycoxidation may damage the enzymes that synthesise glutathione (GSH), an endogenous intracellular antioxidant. Erythrocytes (RBCs) taken from NIDDM subjects, and non-diabetic controls, were GSH-depleted using 1-chloro-2,4-dinitrobenzene, incubated in a solution containing GSH-rebuilding substrates, and sampled for GSH using a 5,5'-gamma-dithiobis-(2-nitrobenzoic acid)/enzymatic recycling procedure. NIDDM subjects, on average, had the same GSH concentration and synthesising ability as non-diabetic controls, indicating normal function of the synthesis enzymes. A positive correlation between synthesis and concentration of GSH seen in non-diabetic controls did not exist in NIDDM, due to their putatively larger oxidative load. The results, to the best of our knowledge, provide the first evidence that, despite a higher oxidative load, intact RBCs from NIDDM subjects are able to synthesise GSH normally. It is hypothesised that increased rates of GSH synthesis would maintain a normal steady-state GSH concentration.

Kinetics of uptake and deacetylation of N-acetylcysteine by human erythrocytes.

Overproduction of reactive oxygen species associated with several diseases including sickle cell anaemia reduces the concentration of glutathione, a principal cellular antioxidant. Glutathione depletion in sickle erythrocytes increases their conversion to irreversible sickle cells that promote vaso-occlusion. Therapeutically, N-acetylcysteine partially restores glutathione concentrations but its mode of action is controversial. Following glutathione depletion, glutathione synthesis is limited by the supply of cysteine and it has been assumed that deacetylation of N-acetylcysteine within erythrocytes provides cysteine to accelerate glutathione production. To determine whether this is the case we studied the kinetics of transport and deacetylation of N-acetylcysteine. Uptake of N-acetylcysteine had a first order rate constant of 2.40+/-0.070min(-1) and only saturated above 10mM. Inhibition experiments showed that 56% of N-acetylcysteine transport was via the anion exchange protein. Deacetylation, measured using (1)H NMR, had a K(m) of 1.49+/-0.16mM and V(max) of 2.61+/-0.08micromolL(-1)min(-1). Oral doses of N-acetylcysteine increase glutathione concentrations in sickle erythrocytes at plasma N-acetylcysteine concentrations of approximately 10microM. At this concentration, calculated rates of N-acetylcysteine uptake and deacetylation were approximately 5% of the rate required to maintain normal glutathione production. We concluded that on oral administration, intracellular deacetylation of N-acetylcysteine supplies little of the cysteine required for accelerated glutathione production. Instead, N-acetylcysteine acts by freeing bound cysteine in the plasma that then enters the erythrocytes. To be effective, intracellular cysteine precursors must be designed to enter erythrocytes rapidly and employ enzymes with high activity within erythrocytes to liberate the cysteine.