Effects of the Perceived Risk of Contracting COVID-19 on Nursing Students' Well-Being

BACKGROUND

Although mental health symptoms increased during the coronavirus disease 2019 (COVID-19) pandemic, little is known about the associations between nursing students' perceived risk of contracting COVID-19 and their academic and psychological well-being. This study examined associations between perceived COVID-19 risk, likelihood of completing nursing education, and mental health factors of nursing students.

METHOD

A total of 979 nursing students completed self-report measures of perceived COVID-19 risk, anticipated academic completion, anxiety and depressive symptoms, stress, coping self-efficacy, hope, and social support.

RESULTS

Students with higher perceived COVID-19 risk reported increased anxiety and depression as well as decreased likelihood of graduating, coping self-efficacy, and levels of social support.

CONCLUSION

Findings indicate the need for increased mental health support for nursing students for successful completion of their programs. Educators should increase support and proactively strengthen positive psychology factors to mitigate the effects of COVID-19 and other crises on nursing students' well-being. [J Nurs Educ. 2022;61(11):641-645.].

Undergraduate versus graduate nursing students: Differences in nutrition, physical activity, and self-reported body mass index

ObjectiveThis study compared self-reported nutrition, physical activity, and body mass index (BMI) in undergraduate versus graduate nursing students.ParticipantsRespondents included 233 undergraduate and 230 graduate nursing students in a Southeastern public university.MethodsThe study was an exploratory, descriptive, cross-sectional comparison administered via online questionnaire including self-reported demographics, nutritional intake, physical activity, and BMI.ResultsUndergraduates reported exercising more than graduate students. Graduate students reported consuming significantly more vegetables than undergraduates; however, more graduate students self-reported BMIs in overweight and obese categories than undergraduates.ConclusionsFindings provide a foundational understanding that interventions or educational programs to improve self-care behaviors of nursing students should be tailored depending on the educational level of the students. Educators must establish self-care skills within nursing students at all levels to help them preserve their health in the fast-paced, strenuous, and stressful work of all echelons of nursing upon completion of the educational program.

Positive and negative psychosocial factors related to healthy and unhealthy weight control among nursing students

BACKGROUND

Although nursing students are educated on the importance of exercising regularly and maintaining a well-balanced diet, many do not practice healthy weight management behaviors, and some even use unhealthy weight loss methods. Yet, little research has examined both positive and negative psychosocial variables related to weight control among nursing students.

PURPOSE

The present study aimed to identify the most salient psychosocial variables related to healthy and unhealthy weight control among nursing students.

METHOD

Using survey data from 241 nursing students, structural equation modeling was conducted to examine the relative contributions of eight interrelated psychosocial variables, including constructs from a strengths perspective (health-specific hope, health self-efficacy, social support, and body satisfaction) and from a deficit perspective (depression, anxiety, weight perception, and barriers to physical activity).

RESULTS

Results showed that the degree to which individuals perceive themselves to be overweight was related to both healthy and unhealthy weight control. Aside from weight perception, health self-efficacy produced the strongest association with healthy weight control, and anxiety produced the strongest association with unhealthy weight control. The structural model explained 23 % of the variance in healthy weight control and 29 % of the variance in unhealthy weight control.

CONCLUSIONS

These findings emphasize the need for tailored, integrated weight management interventions for nursing students that equip them with effective anxiety management skills and build self-efficacy.

A Qualitative Exploration of Desired mHealth App Mechanisms Related to Daily Life Influences for College Nursing Students

Introduction

Mobile health (mHealth) apps are digital health tools that allow for the delivery and access to vital health information, support, and encouragement needed to foster positive behavior change. Designing and developing mHealth solutions based on daily life influences for nursing students is imperative to establishing healthier physical and mental health habits.

Methods

Multiple focus groups (n=10) were conducted, and a questionnaire (n=11) was administered to undergraduate students in the professional nursing component. Themed analysis of focus-group data was conducted along with descriptive analysis of the questionnaire.

Results

All participants stated it has been more difficult to maintain a healthy lifestyle since beginning the nursing program. This deterioration can be attributed to three key areas: mental health needs/support, rigor of nursing school, and decline in positive health choices. Participants stated they would use an mHealth app designed specifically for nursing students to combat deterioration of their health.

Conclusions

The results of this study (100% positive response rate) reveal mHealth applications might be a powerful tool in helping nursing students transform their physical and mental health. It appears that if an mHealth application is created with the specific "must-haves" of nursing students then we might experience a positive shift in health behaviors for nursing students, which will hopefully transcend into their careers as nurses.

A practical approach to obesity prevention: Healthy home habits

ABSTRACT

Families have the potential to foster a healthy home environment aimed at reducing the risk of overweight and obesity. Establishing habits associated with reduced risk of obesity and overweight early in childhood can have lasting effects into adulthood. Nurse practitioners can encourage families to participate in healthy habits by addressing areas of growth for obesity prevention within the home. A review of the most recent literature, approximately over the past decade, was used to provide a consolidated source of reference for healthy home habits for the nurse practitioner. The search included terms such as "obesity," "overweight," "healthy habits," "physical activity," "obesogenic behaviors," "family meals," "screen time," "depression," "sugary beverages," and "portion sizes." The information was synthesized into three content areas: nutrition and consumption, patterns of activity, and stress within the home. Establishing healthy habits early in life can protect against the development of overweight and obesity. Nurse practitioners can serve a vital role in the prevention of pediatric, adolescent, and adult obesity. Equipped with the unique role of assisting those from a diverse patient base, nurse practitioners can inform patients how to improve healthy habits to decrease the likelihood of obesity or overweight. Encouraging behavior change related to the healthy habits associated with the prevention of overweight and obesity can have a long-term impact on the health of an entire family.

Characteristics of Negative and Positive Mental Health Among Nursing Students in the United States

BACKGROUND: Researchers have documented significant psychological problems among nursing students, but findings have been inconclusive as to whether nursing students are "at-risk" for mental health problems compared with their non-nursing peers. AIMS: This study examined whether nursing students have unique mental health characteristics compared with students from other professions. METHOD: Undergraduates (N = 18,312; nursing n = 1,399) were selected from the 2016-2017 National Healthy Minds Study. Participants completed the Patient Health Questionnaire-9 (depression), the Generalized Anxiety Disorder-7 (anxiety), and the Flourishing Scale (positive psychology). RESULTS: Nursing students were equally likely to screen positive for depression and anxiety compared with their non-nursing peers. However, when controlling for gender, age, and year in school, multigroup structural equation modeling analyses revealed that female (but not male) nursing students reported significantly higher levels of specific anxiety symptoms and certain psychological strengths than female students from other professions. Nursing students are equally likely to screen positive for depression or anxiety as their non-nursing peers; however, anxiety disorders may reflect symptom profiles unique to nursing students. CONCLUSIONS: Findings suggest a need for tailored screening and interventions to reduce mental health problems and harness psychological strengths unique to nursing students.

Food insecurity among nursing students: A mixed methods study

BACKGROUND

College students are among 48.1 table million Americans who experience food insecurity, affecting aspects of daily living, health, and academic performance. This study sought to assess food security in nursing students to determine the prevalence and significance of this issue.

METHODS

A mixed-methods descriptive design was utilized to collect and analyze data through an online survey of junior and senior undergraduate nursing students. Both qualitative and quantitative questions were related to personal experience with food insecurity.

RESULTS

Approximately 40% of students responded that they were Sometimes/Often worried that food would run out before the next income arrived. In addition, 52% of the participants Sometimes/Often could not afford an adequate amount of food, and 35% reported having a shortage of food.

CONCLUSION

University leadership, College of Nursing administrators, and nursing faculty should be aware of food insecurity among their students and identify strategies to assess and decrease this issue.

Nursing students' resilience, depression, well-being, and academic distress: Testing a moderated mediation model

AIM

Academic distress is a leading cause of attrition among nursing students. The present study tested a positive psychology-oriented model detailing the potential links between nursing students': (a) psychological resilience; (b) depressive symptoms; (c) intrapersonal well-being; (d) interpersonal well-being; and (e) academic distress. Additionally, we tested whether the academic benefits of resilience were conditional upon nursing students' perceptions of their campus climate as supportive of mental health and well-being.

DESIGN

A correlational, cross-sectional design was employed.

METHOD

Nursing students (N = 933) were selected from the national 2017-2018 Healthy Minds Study (HMS). Students completed measures of resilience, depressive symptoms, intrapersonal well-being (flourishing), interpersonal well-being (belonging), and academic distress.

RESULTS

Conditional process modelling tested depression, belonging, and flourishing as mediators of the associations between resilience and academic distress variables. Furthermore, perceptions of campus climate were included as potential moderators of these mediation effects. Results indicated that the protective academic benefits of resilience were primarily explained by decreases in depression but that this effect was strongest for nursing students with negative perceptions of their campus climate.

CONCLUSION

Findings highlight the psychological and academic benefits of greater resilience and the moderated mediation results suggest that such benefits were conditional on the broader campus climate.

IMPACT

Nurse educators and policymakers should consider addressing contextual factors, such as campus climate, in addition to resilience training in their efforts to reduce the negative academic impacts of mental health problems and stress in nursing school.

Sleep, screen time, and family meal frequency in preschool children: A pilot study

This exploratory pilot study identified the prevalence and perceptions of three healthy habits in preschool-age children by surveying their parents/caregivers. Researchers examined children's hours of sleep, screen time, and number of family meals per week.

Nurse practitioner students' observations of preceptor engagement in obesity management and weight bias: A mixed-methods approach

BACKGROUND

Obesity is considered a growing epidemic in the United States. Nurse practitioners (NPs) have the opportunity to serve as leaders in addressing concerns related to disease management, particularly obesity. Currently, we lack an awareness of how NP students are learning obesity management from their preceptors.

PURPOSE

Thus, the current study sought to explore how NP students perceive preceptors' behaviors when managing patients with obesity.

METHODOLOGICAL ORIENTATION

This study used a mixed-methods design. Participants were asked to report how often they observed their preceptors engage in different strategies when interacting with patients with obesity (e.g., calculate body mass index, identify goals). Students were then asked to respond to the statement: "share observations you made of how patients with obesity were treated in this environment." Students completed 2 clinical rotations during this period and, thus, were asked to answer the questions twice to capture experiences at both clinical sites.

SAMPLE

Researchers surveyed 225 NP students completing clinical rotations in 3 settings (Family Practice, Pediatrics, and Obstetrics/Gynecology).

CONCLUSIONS

Quantitative results revealed significant differences in the frequency of observed obesity management behaviors by all preceptors. Qualitative results revealed that NP students most often observed preceptors displaying interpersonal warmth without weight bias when working with patients with obesity. Contrary to current literature, this sample of NP students observed their preceptors engaging in positive interactions with individuals with obesity.

IMPLICATIONS FOR PRACTICE

Educators must continue to teach students to engage in unbiased behavior toward patients. It is critical to continue to improve obesity management content offered in NP programs.

Characteristics of and Factors Influencing College Nursing Students' Willingness to Utilize mHealth for Health Promotion

More than half of practicing nurses have suboptimal physical or mental health. Impaired health is associated with a 76% higher likelihood that nurses will make medical errors. Improving the health habits of nursing students is essential to shaping and sustaining health prior to joining the workforce. Technology such as mobile health applications holds great promise in facilitating behavioral change and encouraging healthy habits in nursing students. Identifying the predictors of willingness to use mobile health is essential to creating mobile health applications that will engage nursing students and promote sustainable usage. Evaluation of psychological, attitudinal, and health-related correlates of mobile health can highlight predictors of willingness to use mobile health, which can influence nursing students' utilization and long-term engagement with mobile health applications. Analysis of these correlates shows that psychological attributes, such as hope, play a role in the willingness to use and may facilitate engagement in the utilization of a mobile health application. Development of a mobile health application that increases hope and helps establish healthy habits may enable nursing students to remain healthy throughout their lives, creating a new generation of happier, healthier nurses and, ultimately, improving safety for patients under their care.

Advanced Practice Nursing student knowledge in obesity management: A mixed methods research study

BACKGROUND

Obesity, the most prevalent chronic disease affecting multiple systems, is associated with increased mortality and a decreased life expectancy.

OBJECTIVES

The purpose of this study was to identify Advanced Practice Nursing (APN) students' confidence of obesity management as well as satisfaction of APN curriculum on and curricular recommendations regarding obesity management.

DESIGN

Modified convergent mixed-methods design.

SETTING

A university-based college of nursing in the Deep South.

PARTICIPANTS

Graduate APN Students.

METHODS

An exploratory mixed methods online survey was administered to APN students. The survey included demographics; confidence in obesity management; knowledge of pharmacological treatment; self-reported height and weight; experiences and challenges related to obesity management; and suggestions of curricular content changes for the treatment of obesity that would increase student expertise and confidence.

RESULTS

Ninety-nine surveys were completed by 94 female and five male APN students aged 26 to 61 years. The majority (70.7%) were white with BMIs ranging from 19.57 to 51.37 (x̅=27.81). Areas where students were least comfortable were prescribing anti-obesity medications and accurately billing for obesity management. Fourteen percent of APN students reported feeling that their graduate nursing education program did not prepare them well in obesity management, 25.3% reported feeling slightly well prepared, 32% reported feeling moderately well prepared, and 27.8% reported feeling very well or extremely well prepared. Qualitative responses accentuated insecurity in areas such as initiating a discussion on obesity management with patients who have obesity.

CONCLUSIONS

Overall, APN students requested that their curriculum incorporate more instruction on how to begin the discussion of weight loss and provide clear evidence-based guidelines that include diet, exercise, and medication options. An efficient way to affect the management and treatment of obesity is to ensure that the next generation of providers is thoroughly prepared to implement the best evidence-based obesity management for patients.

Exploring Family Communication About Sickle Cell Disease in Adolescence

Sickle cell disease (SCD) is a lifelong disorder that involves progressive organ damage and requires ongoing medical attention to prevent and treat episodic acute complications. Children with SCD need ongoing monitoring and extra attention that may be stressful to family members. Communication within families can help resolve family stress and may be associated with medical follow-up and management of SCD. Focus groups were conducted with 12 African American families to explore the communication that occurred within and outside of the family from the perspectives of adolescents with SCD, siblings, and parents. Factors that influence family communication were explored. The extended family was an important social network and resource to adolescents, siblings, and parents. Family member knowledge of SCD was an important factor that influenced communication about SCD; adolescents and parents communicated more easily than siblings and also reported having more knowledge of SCD than siblings. Future research focusing on the knowledge of immediate and extended family members and their recognition of their contribution to the child with SCD is recommended.

A novel 96-well scintillation proximity assay for the measurement of apoptosis

The translocation of phospholipids across the plasma membrane has been widely documented as one of the earliest measurable biochemical events of apoptosis. Using fluorescently labelled annexin V, which preferentially binds phosphatidylserine (PS) in the presence of Ca(2+), the externalization of PS can be measured and apoptosis quantified using flow cytometry. Conventional detection methods utilizing annexin V, while faster than in situ DNA end-labelling or DNA laddering, require extensive sample preparation which may compromise samples and makes rapid, high volume screening prohibitive. This paper describes a novel assay for the measurement of apoptosis based upon binding of radiolabelled annexin V to apoptotic cells attached to the growth surface of a 96-well scintillating microplate (Cytostar-T(R)). We compared measurements of apoptosis made by flow cytometry to those obtained with the scintillating microplate in three model systems, treatment of: mouse connective tissue (L-M) cells with lymphotoxin (LT), human lung carcinoma (H460) cells with Apo-2 ligand and human umbilical vein endothelial (HUVE) cells with staurosporine. In this assay, we compare both direct and indirect labelling methods by utilizing either iodinated annexin V or biotinylated annexin V/[(35)S] streptavidin to radiolabel apoptotic cells. The signal detected is a direct consequence of the binding of annexin V to externalized PS on apoptotic cells and the proximity of the label to the base of the plate. Using this method, separation of bound and unbound radiolabel signal occurs directly within the well resulting in a sensitive assay that requires minimal manipulation and can accomodate a large number of samples.

DNA sequence analysis of methylene chloride-induced HPRT mutations in Chinese hamster ovary cells: comparison with the mutation spectrum obtained for 1,2-dibromoethane and formaldehyde

Glutathione-S-transferase-mediated metabolism of methylene chloride (MC) generates S-chloromethylglutathione, which has the potential to react with DNA, and formaldehyde, which is a known mutagen. MC-induced mutations in the HPRT gene of Chinese hamster ovary cells have been sequenced and compared with the mutations induced by 1, 2-dibromoethane (1,2-DEB), which is known to act through a glutathione conjugate, and formaldehyde. All three compounds induced primarily point mutations, with a small number of insertion and deletion events. The most common point mutations induced by MC were GC-->AT transitions (4/8), with two GC-->CG transversions and two AT-->TA transversions. This pattern of mutations showed greater similarity with 1,2-DBE, where the dominant point mutations were GC-->AT transitions (7/9), than formaldehyde, where all mutations were single base transversions and 5/6 occurred from AT base pairs. The mutation sequence results for MC suggest that S-chloromethylglutathione plays a major role in MC mutagenesis, with only a limited contribution from formaldehyde. The involvement of a glutathione (GSH) conjugate in MC mutagenicity would be analogous to the well-characterized pathway of activation of 1,2-DBE.

Mouse liver glutathione S-transferase mediated metabolism of methylene chloride to a mutagen in the CHO/HPRT assay

Although methylene chloride (MC) is readily detectable as a bacterial mutagen, published studies in mammalian cells have been inconclusive. We have previously shown (Graves et al., 1995) that glutathione S-transferase (GST)-mediated metabolism of MC by mouse liver cytosol (S100 fraction) causes DNA single-strand (ss) breaks in CHO cells. In this study, MC GST metabolites were shown to cause mutations at the HPRT locus of CHO cells. The mutagenicity of MC was enhanced by exposing the cells in suspension rather than as attached cultures. The MC GST metabolite formaldehyde was mutagenic in independent experiments, although the number of mutants induced was lower than with the MC. CHO HPRT mutations were also induced by the reference genotoxin 1,2-dibromoethane (1,2-DBE), which is activated to a mutagen by GST-mediated metabolism. Assay of DNA ss breaks and DNA-protein cross-links at mutagenic concentrations of MC, formaldehyde or 1,2-DBE, showed that all three compounds induced DNA ss breaks, but only formaldehyde induced significant DNA-protein cross-linking. These results suggest that whilst formaldehyde may play a role in MC mutagenesis, its weak mutagenicity and the absence of significant DNA-protein cross-linking after MC exposure, leads to the conclusion that the MC DNA damage and resulting mutations are induced by the glutathione conjugate of MC, S-chloromethylglutathione.

Methylene chloride-induced DNA damage: an interspecies comparison

DNA single-strand (ss) breaks were detected in the livers of B6C3F1 mice immediately following exposure to 4000-8000 p.p.m. methylene chloride (MC) for 6 h. This damage was undetectable 2 h after exposure, suggesting an active DNA repair process. Similarly, DNA ss breaks were detected in whole lung homogenates taken from mice exposed to 2000-6000 p.p.m. MC. The DNA of mouse Clara cells incubated in vitro with MC was also damaged at concentrations of 5 mM MC and above. Pre-treatment of mice with the glutathione depletor buthionine sulphoximine (BSO) caused a decrease in the amount of DNA damage detected, suggesting a GST-mediated mechanism. DNA damage was also reduced in Clara cells when incubated in vitro with MC in the presence of BSO. In CHO cells induction of DNA damage was dependent upon exogenous MC metabolism by mouse liver S100 fraction (but not microsomes) in the presence of GSH. DNA ss breaks were not induced by MC in hamster hepatocytes in vitro at concentrations from 5 to 90 mM MC, nor in eight individual samples of normal human hepatocytes exposed to MC at similar concentrations. The ability of MC to induce DNA ss breaks in the four species studied is entirely compatible with the known carcinogenicity of this chemical in animals and offers experimental evidence to suggest that humans would not be susceptible to MC-induced liver cancer. The DNA ss breaks correlate with the metabolism of MC by the GST pathway and provide an explanation for the lack of sensitivity of hamsters and rats to MC-induced liver cancer.

Relations between upper limb soft tissue disorders and repetitive movements at work

To make a preliminary assessment of whether upper limb soft tissue disorders might be associated with activities at work, we have conducted a case-control study of subjects attending orthopedic clinics in three cities. All subjects between the ages of 16 and 65 years, in whom defined soft tissue conditions of the upper limb were diagnosed by the participating orthopedic surgeons, were invited to take part. Controls were subjects attending the same clinics within the same age range whose clinical diagnosis did not include disease of the upper limb, cervical or thoracic spine. Information concerning repetitive movements of the upper limbs at work was elicited by questionnaire. Five hundred eighty cases and 996 controls were studied, representing 96% and 93%, respectively, of those invited to participate. The diagnoses of the cases included soft tissue conditions affecting the shoulder, elbow, forearm, wrist, thumb, hand, and fingers. The diagnoses of the controls included traumatic, degenerative, and inflammatory conditions, mostly of the legs and lower back. Women predominated among the cases (70%) and men among the controls (56%). Of 221 female cases with injury to the wrist and forearm, 32 were cleaner/domestics (14.5%) compared to 35 to 439 controls (8%), a difference statistically significant at the 2 1/2% level. Other jobs significantly overrepresented (5% level) among female cases with injuries at various anatomical sites included hairdressers, secretary/temps, assembly line workers, and machine operators (type unspecified). Among male cases, electricians were significantly overrepresented (5% level). Jobs for which there was a suggestion (p < 0.1) of overrepresentation among cases included butchers and teacher/lecturers (both males only) and the combined job groups (chosen a priori for analysis) of keyboard operators, machine operators, and music teachers (all three jobs, females only).

Relationship between hepatic DNA damage and methylene chloride-induced hepatocarcinogenicity in B6C3F1 mice

Methylene chloride (MC) induced DNA damage in freshly isolated hepatocytes from mice and rats, which was detectable as single-strand (ss) breaks by alkaline elution. The lowest in vitro concentration of MC needed to induce DNA damage in mouse hepatocytes (0.4 mM) was much lower than for rat hepatocytes (30 mM), and is close to the calculated steady-state concentration of MC in the mouse liver (1.6 mM) at a carcinogenic dose (4000 p.p.m. by inhalation). DNA ss breaks were also detectable in hepatocyte DNA from mice which had inhaled 4000 p.p.m. MC for 6 h, but not in hepatocyte DNA from rats similarly exposed. In studies with hepatocytes cultured overnight in the presence of buthionine sulfoximine to deplete glutathione (GSH), subsequent exposure to MC resulted in less DNA damage in the GSH-depleted cells. This shows that conjugation of MC with GSH is important in its activation of DNA-damaging species in the liver. The GSH pathway of MC metabolism produces two potential DNA-damaging species, formaldehyde and S-chloromethylglutathione (GSCH2Cl). Formaldehyde is known to cause DNA ss breaks in cells. However, the lowest concentration of formaldehyde required to induce a significant amount of DNA ss breaks in mouse hepatocytes (0.25 mM) is unlikely to be formed following in vitro or in vivo metabolism of MC at concentrations that induce similar amounts of DNA damage. That formaldehyde does not play a role in this DNA damage has been confirmed in experiments with CHO cells exposed to MC and an exogenous activation system from mouse liver (S9 fraction). Formaldehyde was responsible for the DNA- protein cross-linking effect of MC, but did not cause the DNA damage leading to ss breaks. These DNA ss breaks are likely to be caused by GSCH2Cl. The results suggest a genotoxic mechanism for MC carcinogenicity in the mouse liver, and support the proposal that the observed species differences in liver carcinogenicity result from differences in the amount of MC metabolism via the GSH pathway in the target organ.

The role of formaldehyde and S-chloromethylglutathione in the bacterial mutagenicity of methylene chloride

Methylene chloride was less mutagenic in Salmonella typhimurium TA100/NG-11 (glutathione-deficient) compared to TA100, indicating that glutathione is involved in the activation of methylene chloride to a mutagen in bacteria. In rodents, the pathway of methylene chloride metabolism utilizing glutathione produces formaldehyde via a postulated S-chloromethylglutathione conjugate (GSCH2Cl). Formaldehyde is known to cause DNA-protein cross-links, and GSCH2Cl may act as a monofunctional DNA alkylator by analogy with the glutathione conjugates of 1,2-dihaloalkanes. The lack of sensitivity of Salmonella TA100 towards formaldehyde (Schmid et al., Mutagenesis, 1 (1986) No. 6, 427-431) suggests that GSCH2Cl is responsible for methylene chloride mutagenicity in Salmonella. In Escherichia coli K12 (AB1157), formaldehyde was mutagenic only in the wild-type, a characteristic shared with cross-linking agents, whereas 1,2-dibromoethane (1,2-DBE) was more mutagenic in uvrA cells (AB1886). Methylene chloride, activated by S9 from mouse liver, was mutagenic only in wild-type cells, suggesting a mutagenic role for metabolically derived formaldehyde in E. coli. Mouse-liver S9 also enhanced the cell-killing effect of methylene chloride in the uvrA, and a recA/uvrA double mutant (AB2480) which is very sensitive to DNA damage. This pattern was consistent with formaldehyde damage. However, a mutagenic role in bacteria for the glutathione conjugate of methylene chloride cannot be ruled out by these E. coli experiments because S9 fractions did not increase 1,2-DBE mutagenicity, suggesting lack of cell wall penetration by this reactive species. Rat-liver S9 did not activate methylene chloride to a bacterial mutagen or enhance methylene chloride-induced cell-killing, which is consistent with the carcinogenicity difference between the species.

Fpg protein of Escherichia coli is a zinc finger protein whose cysteine residues have a structural and/or functional role

The Fpg protein of Escherichia coli is a DNA repair enzyme with DNA glycosylase, abasic site nicking, and deoxyribose excising activities. Analysis of the amino acid sequence of this protein suggests that the Fpg protein is a zinc finger protein with a Cys-X2-Cys-X16-Cys-X2-Cys motif. Competition experiments show that the Fpg protein substitutes Cu(II), Cd(II), and Hg(II), metal ions classically associated with substitutions in zinc finger proteins. The Fpg protein activities are inhibited following the reaction with a Cys-specific reagent at low protein:reagent ratios, suggesting that these residues are important for the enzymatic activities. Site-directed mutagenesis was used to produce 6 mutant Fpg proteins with Cys-->Gly mutations. Substitution of the zinc in these proteins by 65Zn(II) indicates that all the proteins bind zinc, but the Zn(II) is not retained as strongly in the zinc finger mutants. The mutations in the Fpg protein outside the zinc finger consensus sequence do not eliminate the Fapy-DNA glycosylase and abasic site nicking. One of the Fpg mutant proteins outside the zinc finger has a reduced capacity to release deoxyribose from abasic sites. Cys-->Gly mutations in the zinc finger consensus sequence reduce all three aforementioned activities substantially. The purified Fpg proteins with Cys-->Gly mutations in the zinc finger consensus sequence do not incise DNA at abasic sites with the same efficiency nor mechanism as the native Fpg protein. The wild type Fpg protein and the Fpg proteins mutated outside the zinc finger sequence bind an oligonucleotide with a unique chemically reduced abasic site in a defined sequence as assayed by retention on nitrocellulose filters, whereas the mutant Fpg proteins within the zinc finger sequence do not bind to the same oligonucleotide. Therefore, the disruption of zinc coordination in the zinc finger of the Fpg protein is associated with decreased binding capacity to DNA as well as decreased enzymatic activities.

Clearance of N-nitrosodimethylamine and N-nitrosodiethylamine by the perfused rat liver. Relationship to the Km and Vmax for nitrosamine metabolism

The first-pass clearance of dietary N-nitrosodimethylamine (NDMA) by the liver is the most important factor in the pharmacokinetics of this carcinogen in the rat, but is less important in the pharmacokinetics of N-nitrosodiethylamine (NDEA). The reason for the difference in clearance of these two nitrosamines is not known. These experiments were carried out to see whether the general characteristics of the clearance of these two carcinogens in vivo could be reproduced in the perfused liver, and whether the clearance could be correlated with the Michaelis-Menten parameters Km and Vmax for their metabolism. If this could be done one would be able to predict the possible extent of first-pass clearance of nitrosamines in man from measurement of Km and Vmax for nitrosamine metabolism by the human liver. The Km (22 microM) and Vmax (10.2 and 13.4 nmol/g liver/min) for the metabolism of NDMA by slices from two human livers, the inhibition of that metabolism by ethanol (Ki 0.5 microM), and the rate of N-7 methylation of DNA when slices are incubated with NDMA, were measured. These results are similar to those reported previously with rat liver. The Km (27 microM) for the metabolism of NDEA by rat liver slices and the inhibition of that metabolism by ethanol (Ki 1 microM) were estimated from the rate of ethylation of the DNA of the slices. The clearance of both these nitrosamines by the perfused rat liver was measured, and the results appeared to parallel those in vivo with a striking difference between the clearance of NDMA and NDEA. The maximal rate of clearance of NDMA was 11.2 nmol/g liver/min and of NDEA 8.9 nmol/g liver/min, similar to the Vmax for metabolism of NDMA by liver slices and to the estimated maximal rate of liver metabolism of both nitrosamines in the living rat. However, although the Km for metabolism of these two nitrosamines by liver slices is similar (about 25 microM), the logarithmic mean sinusoidal concentration [see Bass and Keiding, Biochem Pharmacol 37: 1425-1431, 1988] giving half maximal clearance during perfusion (the equivalent to Km) was 2.3 microM for NDMA and 10.6 microM for NDEA. The almost 5-fold difference between these two values is the basis for the difference between the clearance of the two nitrosamines.(ABSTRACT TRUNCATED AT 400 WORDS)

Excision of 5'-terminal deoxyribose phosphate from damaged DNA is catalyzed by the Fpg protein of Escherichia coli

Homogeneous Fpg protein of Escherichia coli has DNA glycosylase activity which excises some purine bases with damaged imidazole rings, and an activity excising deoxyribose (dR) from DNA at abasic (AP) sites leaving a gap bordered by 5'- and 3'-phosphoryl groups. In addition to these two reported activities, we show that the Fpg protein also catalyzes the excision of 5'-terminal deoxyribose phosphate (dRp) from DNA, which is the principal product formed by the incision of AP endonucleases at abasic sites. Moreover, the rate of the Fpg protein catalysis for the 2,6-diamino-4-hydroxy-5-formamidopyrimidine-DNA glycosylase activity is slower than the activities excising dR from abasic sites and dRp from abasic sites preincised by endonucleases. The product released by the Fpg protein in the excision of 5'-terminal dRp from an abasic site preincised by an AP endonuclease is a single base-free unsaturated dRp, suggesting that the excision results from beta-elimination. The release of 5'-terminal dRp by crude extracts of E. coli from wild type and fpg-mutant strains shows that the Fpg protein is one of the major EDTA-resistant activities catalyzing this reaction.

Repair of O6-methylguanine, O6-ethylguanine, O6-isopropylguanine and O4-methylthymine in synthetic oligodeoxynucleotides by Escherichia coli ada gene O6-alkylguanine-DNA-alkyltransferase

Self-complementary oligodeoxynucleotides have been synthesized containing O6-methylguanine (O6meG), O6-ethylguanine (O6etG), O6-isopropylguanine (O6iprG) and O4-methylthymine (O4meT). They anneal in solution to give double-stranded DNA. These double helices have been used as substrates for the DNA repair protein O6-alkylguanine-DNA-alkyltransferase coded for by the ada gene of Escherichia coli. The repair followed second-order chemical kinetics. O6meG was repaired by the 19-kd transferase at a rate of 2.54 x 10(7) M-1 s-1 which is close to the theoretical limit for a diffusion-controlled reaction; O6etG and O4meT are repaired 1,000 and 10,000 times more slowly. The 39-kd alkyltransferase (which is precursor to the 19-kd form) and the 19-kd transferase repaired O6etG at similar rates. O6iprG was not repaired. The repair of oligomers containing O6meG was only slightly inhibited by the presence of nonalkylated oligomers. Oligomers containing O6etG were only slightly more effective as inhibitors of repair than the nonalkylated oligomers, indicating that the transferase does not bind selectively to alkylated DNA. Parallel structural studies have shown that O6-alkylguanine:C and O4-alkylthymine:A base pairs have a similar geometry with the alkylated base displaced into the major groove of the DNA in contrast to O6-alkylguanine:T and O4-alkylthymine:G base pairs which retain the Watson-Crick alignment with N1 of the purine juxtaposed to N3 of the pyrimidine. Measurement of the rate of repair of these different base pairs suggests that pairs with the alkyl group exposed in the major groove may be repaired more rapidly than those with the alkyl group more deeply buried in the helix.

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/6. Effect of ethanol on nitrosamine metabolism and distribution. Implications for the role of nitrosamines in human cancer and for the influence of alcohol consumption on cancer incidence

Alcohol consumption is associated with an increase in the incidence of cancers of several sites, including oesophagus, larynx and mouth. The mechanism of the induction of cancer by alcohol is not clear. Humans are exposed to a variety of carcinogenic N-nitroso compounds. Ethanol changes the pharmacokinetics of nitrosamines in rats particularly by decreasing the ability of the liver to metabolize them. A hypothesis is put forward that the influence of alcohol on human cancer is mediated by its effect on the metabolism and distribution of nitrosamines from the diet, from tobacco smoke and from endogenous synthesis.

Intra-abdominal pressure responses of mineworkers to standard loads

Intra-abdominal pressure (IAP) has been used as the basis for a series of force limits for manual handling based on a limiting pressure criterion of 12 kPa (90 mm Hg). Measurements of the IAP responses to a series of standard loads were carried out on a group of eight instructors from the British coal mining industry. The results showed that there was a very low probability (.0016 or less) of obtaining an IAP value of 12 kPa or greater from the population represented by our sample. Average responses were 33% lower than would have been expected from previous reports on force limits based on IAP measurements. While more data are necessary in order to confirm the applicability of these findings to the general mining population, the results clearly suggest that greater loads could safely be lifted by mineworkers than can be lifted by the industrial population represented by the guidelines.