The evaluation of early stage oxidative status in streptozotocin induced diabetes in rats.

Early-stage diabetes can be defined as the stages before absolute insulin deficiency in patients. In this study, the early stage oxidative effect of streptozotocin(STZ) induced diabetes mellitus was evaluated. 28 male adult Sprague-Dawley rats were divided into four groups; control group and 7th, 14th, 21st days diabetic groups. Diabetic groups received single 65 mg/kg STZ injection intraperitoneally. Rats were decapitated at 7th, 14th and 21st days, liver tissues were taken. Nitric oxide(NO), malondialdehyde(MDA) levels and catalase, arginase activities were measured. MDA and NO levels were increased (respectively p < .001 and p < .01), mainly 14 and 21 days after STZ administration; moreover, while liver catalase activity was progressively decreased (p < .001), oppositely arginase was increased in the same time period (p < .01). Results show that MDA and nitric oxide together with catalase and arginase switch at an early stage of diabetes and they may contribute to subsequent complications related to diabetes via increased oxidative damage.

How to perform an excellent radiology board examination: a web-based checklist.

BACKGROUND: Board exams are now considered as means of quality procedures that aim to keep the professional knowledge and skills of the physicians at the highest level. In addition, for an assessment to be scientifically valid, it has to be done within defined standards. Although there are different sources in this field, there is a need for a resource that details the steps required for the examinations to be performed perfectly, brings descriptions of the reasons for the procedure and associates the steps with assessment standards. Experts with national and international experience both in radiology and medical education contributed to the preparation of this checklist. RESULTS: The guide includes 174 elements to consider before, after the exam order and examination. From the perspective of assessment standards, it has been observed that the steps to be considered before the exam have a greater impact on the validity and reliability of the exam. The standard in which the questions are most associated was validity with 117 (67.24%) questions. CONCLUSIONS: We think that our guide, which will be accessible in the web environment, will be useful to the teams with a development goal or just start the exam, the candidates who will take the exam and the examiners.

Calcium Fructoborate Prevents Skin Cancer Development in Balb-c Mice.

Tumor microenvironment, genetic, and non-genetic factors are responsible for the atypical metabolic feature of cancer cells. Aberrant activity of PI3K/Akt pathway, increased glycolytic flux, and decreased intracellular pH gradient are the leading causes of this feature. Calcium Fructoborate (CaFB), a sugar-borate ester, has major benefits for human health. The aim of this study was to explore the implication of CaFB on experimentally induced skin cancer in vivo. According to the treatment, 92 female Balb-c mice are divided into six groups: control, CaFB (3 mg/kg/day), 7,12-Dimethylbenz(a)anthracene (DMBA)+12-O-tetradecanoylphorbol-13-acetate (TPA) (97.5 nmol DMBA, 6.5 nmol TPA), T1: CaFB+DMBA+TPA (3 mg/kg/day CaFB together with DMBA), T2: DMBA+CaFB+TPA (3 mg/kg/day CaFB together with TPA), T3: DMBA+TPA+CaFB (3 mg/kg/day CaFB after tumor formation). Topical DMBA and TPA application resulted in a significant increase in the protein levels, immunoreactivity, and mRNA expression of HRAS, HIF1α, Akt, and PTEN (p < 0.05). Moreover, an increase in the number of TUNEL-positive cells was observed in DMBA-TPA group compared with the control group (p < 0.05). CaFB application reduced the protein levels, immunoreactivity, and mRNA expressions of HRAS, HIF1α, Akt, and PTEN and also decreased the number of TUNEL-positive cells. Recent evidence obtained from our study validated that CaFB treatment may have skin cancer-preventing effect.

Preclinical students' views on medical ethics education: a focus group study in Turkey / Puntos de vista de estudiantes de pre-clínica sobre educación en ética médica: un estudio de grupo focal en Turquía / A perspectiva dos estudantes pré-clínicos sobre o ensino da ética médica: um estudo de grupo focal na Turquia

Abstract: 18. Aim: We aimed to receive the opinions of the preclinical medical students on medical ethics education, and to present some suggestions for the education program. Methods: Focus group discussions were held with third-grade medical students. The analyses were implemented using Creswell's six-step qualitative data analysis. Results: During the data analysis, themes with the following titles were identified: necessity of the education, content, education methods, assessment, participation, contribution of the education, moving to clinical training and suggestions. Discussion: The students stated that the discussions on movies/books/case-based scenarios are more useful than lectures. Although they believed that student assessment was necessary for the medical ethics education, they had negative attitudes towards Multiple Choice Questions. At the stage of moving to the clinical training, their feelings and thoughts about the learning outcomes they would gain from ethical education were contradictory. Conclusion: Each theme and code obtained from the students' expressions may contribute to improving medical ethics education for all institutions. Besides student education, it is also necessary the faculty development programs on medical ethics education for clinical teachers. Additionally, further studies can be conducted on the actions that need to be taken to help students internalize the ethical issues and feel the need of learning more.

Resumen: 22. Nuestro objetivo consistió en recibir las opiniones de estudiantes de medicina en pre-clínica sobre educación en ética médica y presentar algunas sugerencias para el programa de educación. Métodos: Se mantuvo discusiones de grupo focal con estudiantes de medicina de tercer grado. Se implementó el análisis cualitativo de datos de seis pasos de Creswell. Resultados: Mediante el análisis de datos, se identificaron los siguientes temas: necesidad de la educación, contenido, métodos de educación, evaluación, participación, contribución de la educación, el paso a formación clínica y sugerencias. Discusión: Los estudiantes consideraron que las discusiones sobre películas/libros/escenarios de casos eran más útiles que las clases dictadas. Aunque pensaban que la evaluación de los estudiantes era necesaria para la educación en ética médica, no valoraron positivamente las pruebas de preguntas con respuesta múltiple. En el paso a la formación clínica, sus sentimientos y pensamientos sobre los resultados del aprendizaje en educación ética eran contradictorios. Conclusión: Cada tema y código obtenido de las propuestas de los estudiantes puede contribuir a mejorar la educación en ética médica en las instituciones. Además de la educación, también es necesario desarrollar programas sobre educación ética médica para los profesores clínicos. Además, se pueden realizar más estudios sobre las acciones que se necesitan tomar para ayudar a los estudiantes a internalizar los temas éticos y sentir la necesidad de aprender más.

Resumo: 26. Objetivo: tivemos como objetivo coletar as opiniões dos estudantes pré-clínicos de medicina no ensino da ética médica e apresentar algumas sugestões para o programa de ensino. Métodos: foram realizadas discussões em grupos focais com estudantes do 3º período de medicina. As análises foram implementadas usando o método qualitativo de seis etapas de Creswell. Resultados: Durante a análise de dados, os seguintes temas foram identificados: a necessidade da educação, conteúdo, métodos de ensino, avaliação, participação, contribuição da educação, transição para o treinamento clínico e sugestões. Discussão: Os alunos concluíram que as discussões sobre filmes/livros/estudos de caso são mais úteis que aulas expositivas. Embora eles acreditassem que a avaliação de alunos era necessária para o ensino da ética médica, eles tinham atitudes negativas em relação a questões de múltipla escolha. Na fase de transição para o treinamento clínico, seus sentimentos e pensamentos sobre os resultados da aprendizagem, que eles obteriam com o ensino da ética eram contraditórios. Conclusão: Cada tema e código obtidos das opiniões dos alunos podem contribuir para melhorar o ensino da ética médica para todas as instituições. Além do ensino dirigido ao aluno, é necessário que haja também programas de desenvolvimento do corpo docente acerca da educação de ética médica. Ademais, mais estudos podem ser realizados sobre as ações que precisam ser tomadas para ajudar os alunos a interiorizar as questões éticas e sentir a necessidade de aprender mais a respeito.

PRECLINICAL STUDENTS' VIEWS ON MEDICAL ETHICS EDUCATION: A FOCUS GROUP STUDY IN TURKEY.

AIM: We aimed to receive the opinions of the preclinical medical students on medical ethics education, and to present some suggestions for the education program. METHODS: Focus group discussions were held with third-grade medical students. The analyses were implemented using Creswell's six-step qualitative data analysis. RESULTS: During the data analysis, themes with the following titles were identified: necessity of the education, content, education methods, assessment, participation, contribution of the education, moving to clinical training and suggestions. DISCUSSION: The students stated that the discussions on movies/books/case-based scenarios are more useful than lectures. Although they believed that student assessment was necessary for the medical ethics education, they had negative attitudes towards Multiple Choice Questions. At the stage of moving to the clinical training, their feelings and thoughts about the learning outcomes they would gain from ethical education were contradictory. CONCLUSION: Each theme and code obtained from the students' expressions may contribute to improving medical ethics education for all institutions. Besides student education, it is also necessary that the faculty develop programs on medical ethics education for clinical teachers. Additionally, further studies can be conducted on the actions that need to be taken to help students internalize the ethical issues and feel the need of learning more.

Nuestro objetivo consistió en recibir las opiniones de estudiantes de medicina en pre-clínica sobre educación en ética médica y presentar algunas sugerencias para el programa de educación. Métodos: Se mantuvo discusiones de grupo focal con estudiantes de medicina de tercer grado. Se implementó el análisis cualitativo de datos de seis pasos de Creswell. Resultados: Mediante el análisis de datos, se identificaron los siguientes temas: necesidad de la educación, contenido, métodos de educación, evaluación, participación, contribución de la educación, el paso a formación clínica y sugerencias. Discusión: Los estudiantes consideraron que las discusiones sobre películas/libros/escenarios de casos eran más útiles que las clases dictadas. Aunque pensaban que la evaluación de los estudiantes era necesaria para la educación en ética médica, no valoraron positivamente las pruebas de preguntas con respuesta múltiple. En el paso a la formación clínica, sus sentimientos y pensamientos sobre los resultados del aprendizaje en educación ética eran contradictorios. Conclusión: Cada tema y código obtenido de las propuestas de los estudiantes puede contribuir a mejorar la educación en ética médica en las instituciones. Además de la educación, también es necesario desarrollar programas sobre educación ética médica para los profesores clínicos. Además, se pueden realizar más estudios sobre las acciones que se necesitan tomar para ayudar a los estudiantes a internalizar los temas éticos y sentir la necesidad de aprender más.

Objetivo: Coletar as opiniões dos estudantes pré-clínicos de medicina no ensino da ética médica e apresentar algumas sugestões para o programa de ensino. Métodos: foram realizadas discussões em grupos focais com estudantes do 3° período de medicina. As análises foram implementadas usando o método qualitativo de seis etapas de Creswell. Resultados: Durante a análise de dados, os seguintes temas foram identificados: a necessidade da educação, conteúdo, métodos de ensino, avaliação, participação, contribuição da educação, transição para o treinamento clínico e sugestões. Discussão: Os alunos concluíram que as discussões sobre filmes/livros/estudos de caso são mais úteis que aulas expositivas. Embora eles acreditassem que a avaliação de alunos era necessária para o ensino da ética médica, eles tinham atitudes negativas em relação a questões de múltipla escolha. Na fase de transição para o treinamento clínico, seus sentimentos e pensamentos sobre os resultados da aprendizagem, que eles obteriam com o ensino da ética eram contraditórios. Conclusão: Cada tema e código obtidos das opiniões dos alunos podem contribuir para melhorar o ensino da ética médica para todas as instituições. Além do ensino dirigido ao aluno, é necessário que haja também programas de desenvolvimento do corpo docente acerca da educação de ética médica. Ademais, mais estudos podem ser realizados sobre as ações que precisam ser tomadas para ajudar os alunos a interiorizar as questões éticas e sentir a necessidade de aprender mais a respeito.

A multicenter study: how do medical students perceive clinical learning climate?

BACKGROUND: The relationship between students and instructors is of crucial importance for the development of a positive learning climate. Learning climate is a multifaceted concept, and its measurement is a complicated process. The aim of this cross-sectional study was to determine medical students' perceptions about the clinical learning climate and to investigate differences in their perceptions in terms of various variables. METHODS: Medical students studying at six medical schools in Turkey were recruited for the study. All students who completed clinical rotations, which lasted for 3 or more weeks, were included in the study (n=3,097). Data were collected using the Clinical Learning Climate Scale (CLCS). The CLCS (36 items) includes three subscales: clinical environment, emotion, and motivation. Each item is scored using a 5-point Likert scale (1: strongly disagree to 5: strongly agree). RESULTS: The response rate for the trainees was 69.67% (n=1,519), and for the interns it was 51.47% (n=917). The mean total CLCS score was 117.20±17.19. The rotation during which the clinical learning climate was perceived most favorably was the Physical Therapy and Rehabilitation rotation (mean score: 137.77). The most negatively perceived rotation was the General Internal Medicine rotation (mean score: 104.31). There were significant differences between mean total scores in terms of trainee/intern characteristics, internal medicine/surgical medicine rotations, and perception of success. CONCLUSION: The results of this study drew attention to certain aspects of the clinical learning climate in medical schools. Clinical teacher/instructor/supervisor, clinical training programs, students' interactions in clinical settings, self-realization, mood, students' intrinsic motivation, and institutional commitment are important components of the clinical learning climate. For this reason, the aforementioned components should be taken into consideration in studies aiming to improve clinical learning climate.

Exposure of Students to Emotional and Physical Violence in the School Environment.

INTRODUCTION: While peer abuse or physical violence in school is emphasized more, the physical and emotional violence caused by school staff has been emphasized less. The purpose of this study was to investigate the variables related to emotional and physical violence that students are exposed to in the school environment. METHODS: This cross-sectional and descriptive study was conducted by applying a questionnaire to 434 fifth-grade students receiving education in the primary schools in Konak district of Izmir province. Being prepared by the researchers of this study, the questionnaire consisted of questions about the socio-demographic features of the child and the family, the place where the child has been raised, family income, average grade, and the emotional and physical violence of teachers, parents, and peers s/he has been exposed to within the last year. The Chi-square test, Mann-Whitney U test, and logistic regression analysis were used for statistical analyses. RESULTS: The study group consisted of 214 (49.3%) female and 220 (50.7%) male students. Students reported that they were exposed to at least one type of emotional violence from 59.4% of teachers, 52.8% of parents, and 61.8% of children at school; they were exposed to at least one type of physical violence from 42.9% of teachers, 33.6% of parents, and 24.9% of children at school. While the rate of encountering with the beating of another child was 53%, the rate of watching this in television/cinema was 52.8%. Regarding exposure to at least one type of violence, males were found to be significantly more exposed to emotional and physical violence from male teachers, female teachers, and fathers and physical violence from children at school. The factors regarding the exposure to emotional and physical violence by teachers were evaluated using logistic regression analysis, and it was determined that the physical violence from teachers, emotional violence from children in school, and emotional violence from parents could predict the emotional violence from teachers. For males, physical violence from children in school and emotional violence from teachers could predict the physical violence from teachers. CONCLUSION: In this study, the determination of the tendency of togetherness of different types of violence applied to students from different people groups like teachers, parents, and children in school makes us think about the possibility of common risk factors in terms of violence exposure. The risk factors determined in this study may guide us in planning protective interventions aimed at violence.

Sexual attitudes, behaviour changes and opinions of interns in Izmir, Turkey.

OBJECTIVES: To evaluate sexual attitudes, behaviour and opinions of students at the end of their medical education studies in Izmir, Turkey, and compare findings with the results of the study carried out when they were first-year students. METHODS: A cross-sectional and longitudinal study, with data collected via a questionnaire. RESULTS: 'Friends' were most often mentioned as the source of their personal sexual information by students on both occasions. Use of the 'internet' increased significantly during the five years. Pornography and health professionals/specialists' also gained in importance but remained among the less frequently used sources of information. The most frequent factor affecting sexual attitudes and behaviour for both years was 'my own desire and values'. Most (74.8%) interns had taken only a few sexual health histories and 16.5% never; 35% believed their education would enable them to take one. Nearly half (48.5%) said being a medical student changed their opinions on sexuality and 25.7% said they changed their behaviour. DISCUSSION: Although changes were observed in sexual attitudes, behaviour and opinions between the two questionnaires many problems still exist. This study may add to the improvement of medical education regarding sexual health education and its practices.

An example of program evaluation project in undergraduate medical education.

Revisions to existing program evaluation approaches of the Dokuz Eylul University School of Medicine (DEUSM) were made by the Medical Education Department in June 2005. After considering several evaluation models, a mixed evaluation model was developed to meet institutional needs. The general program evaluation plan was structured as areas of inquiry under the three main program evaluation questions: what are the effects of the educational program on students and graduates, what are the effects of the educational program on trainers, and is the educational program being implemented as planned. The School's first report made through its new program evaluation approach was prepared in July 2006, leading to important revisions to the educational program. This article presents DEUSM's project to revise its program evaluation approach and briefly discusses its early implementation.

Sexual attitudes and risk-taking behaviors of high school students in Turkey.

BACKGROUND: The risk of sexually transmitted diseases is high but opportunities of sexual education for adolescents are limited in Turkey. The aim of this study was to evaluate sexual attitudes and behaviors and to determine the predictors of sexual initiation among adolescents. METHODS: A questionnaire designed by the researchers was administered to 861 senior year high school students in their classrooms. RESULTS: The rates of masturbation and sexual intercourse and the median partner numbers among males were higher than females. The rates of having negative feelings after the first sex among females were higher than males. The rates of having sexual intercourse and the mean age at first sexual intercourse among males were similar to developed countries. However, the use of a condom at first intercourse was low. Lower academic performance and grade repetition experience among males and cigarette smoking among both gender groups were related to having sexual intercourse. CONCLUSIONS: This is one of the first studies about sexual risk-taking behaviors among high school students in Turkey. Differences found between gender groups regarding attitudes and behaviors reflect the social structure in Turkey. These findings may be helpful in producing effective solutions for improving education and preventive health care.

Effects of febrile and afebrile seizures on oxidant state in children.

No comparative studies have addressed the oxidant and antioxidant states of blood and cerebrospinal fluid. To reveal this differential state, the study was designed to identify the seizure type with the worse prognosis by determining erythrocyte arginase and erythrocyte catalase, plasma and cerebrospinal fluid malondialdehyde, and plasma and cerebrospinal fluid nitric oxide levels. Study groups were classified as febrile (group 1, n = 21), afebrile (group 2, n = 21), and control (group 3, n = 41, subdivided as 3a, febris positive, convulsion negative, and 3b, febris negative, convulsion negative). Levels of erythrocyte arginase, erythrocyte catalase, plasma malondialdehyde, cerebrospinal fluid malondialdehyde, plasma nitric oxide, and cerebrospinal fluid nitric oxide levels were determined for all groups. A difference was detected between the control and febrile seizure groups with respect to erythrocyte catalase and plasma and cerebrospinal fluid levels of nitric oxide (P < 0.05). Both febrile states and convulsions influence oxidative mechanism. Oxidative stress-generating potential differs for febrile and afebrile seizures. In afebrile seizures, greater levels of oxidative stress might affect prognosis adversely. This phenomenon can be interpreted in terms of fever as a protective factor against possible neurological damage during convulsive seizures.

Sexual behaviours and contraception among university students in Turkey.

The aim of this study was to evaluate the sexual attitudes and behaviours of university students. An anonymous questionnaire was administered to 550 final-year university students aged 20-25 years in Izmir, Turkey. Male students opposed premarital sexual intercourse for both genders more than female students did. The frequency of sexual intercourse among male students (61.2%) was higher than that among female students (18.3%). The mean age of first sexual intercourse was lower among male than among female respondents. The rate of condom use at first sexual intercourse was 47.4%. The frequency of having two or more past sexual partners and masturbation was higher among males than females. It was found that there were culture-specific and gender-dependent differences in sexual attitudes and behaviours of the university students. These results may help in the planning of education and health policies in Turkey.

Effects of additional Vitamin E and selenium supply on G6PDH activity in rats treated with high doses of glucocorticoid.

The aim of this work was to determine the effects of dietary intake Vitamin E and selenium (Se) on glucose-6-phosphate dehydrogenase (G6PDH) activity in rats treated with high doses of prednisolone. Two hundred and fifty adult male Wistar rats were randomly divided into five groups. The rats were fed a normal diet, but groups 3, 4, and 5 received a daily supplement in their drinking water of 20mg Vitamin E, 0.3mg Se, and a combination of Vitamin E and Se, respectively, for 30 days. For 3 days subsequently, the control group (group 1) was treated with a placebo, and the remaining four groups were injected intramuscularly with 100 mg/kg body weight prednisolone. After the last administration of prednisolone, 10 rats from each group were killed at 4, 8, 12, 24, and 48 h and the activities of G6PDH enzymes in their tissues were measured. Hepatic and spleen G6PDH activities in the prednisolone treatment group began to decrease gradually at 8 h, while enzyme activities did not change in the kidney and heart. However, the administration of Vitamin E alone did not affect G6PDH activity in any of the tissues. Se supplementation had a preventive effect on the decrease of G6PDH caused by prednisolone and improved the diminished activities of G6PDH. Therefore, the present study demonstrates that a high dose of prednisolone may alter the effects of normal dose glucocorticoids and that Se is effective in reducing damage in prednisolone-treated rats. Se may prevent the changes in G6PDH activity in various tissues caused by prednisolone in various tissues.

Perceptions of first and third year medical students on self-study and reporting processes of problem-based learning.

BACKGROUND: The objective of this study is to investigate the perceptions of first and third year medical students on self-study and reporting processes of Problem-based Learning (PBL) sessions and their usage of learning resources. METHODS: The questionnaire applied to the students consisted of; questions about students' perceptions on searching and preparing phases of the self-study process, the breadth and depth of discussion during reporting phase and the usage of learning resources. RESULTS: First-year students spent more time for self-study and more highly rated the depth of discussion compared to third-year students. The searching and preparing phases of the self-study process were considered as statistically important factors strongly influencing the breadth and depth of discussion during the reporting phase. The effect of extensiveness of searching on the depth of discussion was negative among the first-year students, and positive among third-year students. CONCLUSIONS: The relative shortness of third-year students' self-study periods can be related to their mental weariness, decreased motivation or first-year students' slowness in accessing appropriate resources. The third-year students' more frequent use of textbooks may be due to the improvement of their abilities in reaching relevant learning resources. The findings implied that the increase in students' PBL experience paralleled the development of their discussion skills using different learning resources.

Oxidative damage and antioxidant enzyme activities in experimental hypothyroidism.

Free radicals are now well known to damage cellular components. To investigate whether age and thyroid level affect peroxidation speed, we examined the levels of malondialdehyde and antioxidant enzyme activities in different age groups of hypothyroid rats. Hypothyroidism was induced in 30- and 60-day-old Wistar Albino rats by the i.p. administration of propylthiouracil (10 mg kg(-1) body weight) for 15 days. While malondialdehyde levels of 30- or 60-day-old hypothyroid rats were increased in liver, they were decreased in the tissues of the heart and thyroid. While glucose-6-phosphate dehydrogenase activity levels did not change in heart, brain and liver tissues of 30-day-old rats, they increased in brain and heart tissues of 60-day-old experimental groups, but decreased in the liver. Catalase activities decreased in the liver and heart of rats with hypothyroidism, but increased in erythrocytes. In control groups while malondialdehyde levels increased in brain, heart and thymus with regard to age, they decreased in plasma. Glucose-6-phosphate dehydrogenase and catalase activities were not affected by age in tissues of the thymus, thyroid and brain, but they were decreased in the heart tissue. The changes in the levels of lipid peroxidation and antioxidant enzyme activities which were determined in different tissues of hypothyroid rats indicate a cause for functional disorder of these tissues. Moreover, there may be changes depending on age at lipid peroxidation and antioxidant enzyme activity levels.

Effects of dietary vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of glucocorticoid.

The effects of dietary intake of vitamin E and selenium on arginase activity in the liver, kidneys, and heart of rats treated with high doses of prednisolone were investigated. Rats were divided into five groups. Groups 3, 4, and 5 received a daily supplement in their drinking water of vitamin E, Se, and a combination of vitamin E and Se, respectively, for 30 days. For 3 days subsequently, the control group (group 1) was given a placebo, and the remaining four groups were injected intramuscularly with prednisolone. The tissue samples were collected from each group at 4, 8, 12, 24, and 48 h after the last administration of prednisolone. In the group treated with prednisolone alone, arginase activity in the liver was found to have increased at all the time periods, whereas it had decreased significantly in the heart at 48 h. Arginase activity in the kidneys was not affected by prednisolone. Compared to the control and prednisolone groups, arginase activity in the kidneys and heart of the vitamin E- and Se-supplemented groups was found to be significantly increased at all time periods, however, no difference was seen in the combination group. Arginase activity in the liver of the vitamin E-supplemented group was found to have decreased at all time periods, however, in the Se group compared to the prednisolone group it had reduced at 24 and 48 h only. In the combination group compared to the prednisolone group, liver arginase activity increased constantly up to 12 h returning to normal values at 48 h. Vitamin E and Se in combination may prevent the changes in arginase activity in various tissues caused by prednisolone.

Comparison of pyruvate kinase variants from breast tumor and normal breast.

BACKGROUND: Pyruvate kinase isozymes in human breast tumor tissue were compared in this study with normal human breast tissue. Two forms of pyruvate kinase present in normal and tumor human breast were purified by ammonium sulfate precipitation, dialysis, gel filtration, ion exchange, and affinity chromatography. Molecular weight of the native enzyme was determined. METHODS: Presence of pyruvate kinase activity was examined in normal and tumor breast tissues. Pyruvate kinase was purified with Sephadex DEAE-50, Sepharyl S-200, and Blue Sepharose CL-6B chromatography. Spectrophotometric methods were used to determine activities of pyruvate kinase. RESULTS: Molecular weights of fractions I and II as determined by gel filtration on Sepharyl S-200 were 135,000 Da, 260,000 Da in normal breast tissue, and 72,000 Da, 250,000 Da in tumor breast tissue, respectively. Fractions I and II of pyruvate kinase may be purified approximately 1,591-fold, 636.4-fold in normal breast tissue and 219-fold, 318-fold in tumor breast tissue, respectively. Pyruvate kinase activity in tumor tissue was found higher than in normal tissue. Only tumor fraction II showed tumor-specific sensitivity to L-cysteine. L-phenylalanine inhibited both fractions I and II of normal breast and fraction I of tumor breast, but not fraction II of pyruvate from tumor. ATP inhibited normal and tumor fraction I of pyruvate kinase. The influence of ATP on enzyme activity from normal and tumor fraction II depended upon its concentration. CONCLUSIONS: It was thought that isozymes of pyruvate kinase from human breast tissue might be M1 and M2 isozymes when compared with those of other tissue pyruvate kinase isoenzymes. Fraction II from breast tumor represented different sensitivity to L-cysteine, L-phenylalanine, and specific activity in comparison with fraction II from normal breast. Different kinetic behavior of fractions in the human breast tumors may support the concept of an isozyme shift.