Taming the sphinx: Mechanisms of cellular sphingolipid homeostasis.

Sphingolipids are important structural membrane components of eukaryotic cells, and potent signaling molecules. As such, their levels must be maintained to optimize cellular functions in different cellular membranes. Here, we review the current knowledge of homeostatic sphingolipid regulation. We describe recent studies in Saccharomyces cerevisiae that have provided insights into how cells sense changes in sphingolipid levels in the plasma membrane and acutely regulate sphingolipid biosynthesis by altering signaling pathways. We also discuss how cellular trafficking has emerged as an important determinant of sphingolipid homeostasis. Finally, we highlight areas where work is still needed to elucidate the mechanisms of sphingolipid regulation and the physiological functions of such regulatory networks, especially in mammalian cells. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

Genomic analysis of severe hypersensitivity to hygromycin B reveals linkage to vacuolar defects and new vacuolar gene functions in Saccharomyces cerevisiae.

The vacuole of Saccharomyces cerevisiae has been a seminal model for studies of lysosomal trafficking, biogenesis, and function. Several yeast mutants defective in such vacuolar events have been unable to grow at low levels of hygromycin B, an aminoglycoside antibiotic. We hypothesized that such severe hypersensitivity to hygromycin B (hhy) is linked to vacuolar defects and performed a genomic screen for the phenotype using a haploid deletion strain library of non-essential genes. Fourteen HHY genes were initially identified and were subjected to bioinformatics analyses. The uncovered hhy mutants were experimentally characterized with respect to vesicular trafficking, vacuole morphology, and growth under various stress and drug conditions. The combination of bioinformatics analyses and phenotypic characterizations implicate defects in vesicular trafficking, vacuole fusion/fission, or vacuole function in all hhy mutants. The collection was enriched for sensitivity to monensin, indicative of vacuolar trafficking defects. Additionally, all hhy mutants showed severe sensitivities to rapamycin and caffeine, suggestive of TOR kinase pathway defects. Our experimental results also establish a new role in vacuolar and vesicular functions for two genes: PAF1, encoding a RNAP II-associated protein required for expression of cell cycle-regulated genes, and TPD3, encoding the regulatory subunit of protein phosphatase 2A. Thus, our results support linkage between severe hypersensitivity to hygromycin B and vacuolar defects.

Occupational health nursing in Canada: its social foundation and future.

Our purpose in examining the social foundation of occupational health nursing is to better determine the future direction of the profession and its impact on a diverse workforce. Part of what makes up the profession of occupational health nursing is found in its definition: a process that is determined by the interaction between the occupational health nurse, worker, work and workplace; its goal is to assist the worker to achieve his or her optimal level of functioning, primarily through health education, health promotion, prevention of disease and injury and crisis intervention. Much of occupational health nursing is also based on its history and the traditions that have been established. A true understanding, then, of what occupational health nursing's future can be comes from a solid understanding of the history of the profession. As social trends in the past affected the profession, so will they in the future.

Effect of suckling on pituitary responsiveness to gonadotropin-releasing hormone throughout the early postpartum period of beef cows.

The objective of this study was to compare pituitary responsiveness to gonadotropin-releasing hormone (GnRH) throughout the early postpartum period (PP) in beef cows suckling in single calf vs cows which had calves removed at birth. The experiment utilized 48 cows in a 2 X 4 factorial. Main effects studied were suckling status (suckled or nonsuckled) and days PP (d 3, 10, 20 or 30). Covariates studied were pre-treatment concentrations of progesterone (P), estradiol-17 beta (E), luteinizing hormone (LH) and follicle stimulating hormone (FSH). Suckled (S) cows nursed one calf, while nonsuckled (NS) cows had calves removed at birth. Treatment was a single im injection of 100 micrograms GnRH dissolved in saline. Pre-GnRH plasma concentrations of E, P, LH and FSH and post-treatment plasma concentrations of LH and FSH were determined at 15 min intervals (-30 to 360 min) in blood samples collected via jugular cannulae. Post-treatment plasma concentrations of P were determined at 6 (n = 23) or 8 (n = 23) days after treatment to monitor ovarian response. Concentrations of E, LH and FSH before GnRH injection did not differ (P greater than .1) between S and NS cows at any PP stage and data were pooled for statistical analyses. Pre-treatment LH, but not FSH, increased (r = .43; P less than .002 (with days PP and concentrations of LH were greater (P less than .05) at 30 d than at 3 d PP. Pre-treatment P was greater (P less than .05) in NS than in S cows on d 30 PP and P was correlated (r = .51; P less than .01) with days PP in NS cows. However, the frequency of cows exhibiting plasma P greater than or equal to 1 ng/ml prior to GnRH was low on all days studied and was similar for both groups. LH release after GnRH was correlated with increasing days PP in both S (r = .73; P less than .001) and NS (r = .61; P less than .002) cows, Releasable FSH was not related to days PP in either group. Mean peak LH and total LH released were greater (P less than .025 and P less than .05), respectively) in S than in NS cows at 30 d PP. Mean peak FSH and total FSH released were greater (P less than .05 and P less than .07, respectively) at 10 and 30 d PP in S cows than in NS cows. Pre-treatment E, but no P, LH or FSH was positively related (P less than .01) to GnRH-mediated LH release in both groups. When pre-treatment E was partitioned into separated regressions for S (ES) and NS (ENS) cows, increased pituitary LH response in S cows on d 30 appeared to be due in part to a greater sensitivity of S cows to E modulation. We found no evidence to suggest that pituitary responsiveness per se is decreased in beef cows suckling a single calf.

Identifying sources of disease in agriculture: a role for occupational health nurses.

1. Agriculture is one of the most hazardous industries in the United States, vying with mining and construction as the industry with the highest work fatality rate. 2. Over 40% of Midwestern farm operators also work off the farm. Understanding the disease risks of farming can help the occupational health nurse provide comprehensive care to these dual workers. 3. Sources of disease in agriculture may be physical, chemical, biological, or psychosocial in nature. 4. Effective strategies in the control of agricultural hazards include engineering modifications, use of personal protection products, and educational efforts.

Health care worker incidents reported in a rural health care facility: a descriptive study.

About eight million workers, or 6.4% of the total United States work force, are employed by the health care industry. Frequency of injury has continued to rise from 6 per 100 full time workers in 1980 to over 10 in 1992 (US Department of Labor, 1994). This descriptive, retrospective study characterizes host, agent, and environmental variables for 120 incidents reported in 1990 at a rural nursing home and acute care hospital with 290 employees. Incident is defined as an event that results in injury or has the potential to result in an injury. Based on an estimate of full time equivalents (190.4 FTE) calculated at 9 months, the incident rate per 100 FTEs was 63 for this facility. Injury was reported in 114 incidents, resulting in an overall injury rate per 100 FTEs of 59.9. Sprains and strains were the most frequently reported nature of injury followed by cuts, lacerations, and punctures. Female and male workers reported similar proportions of incidents. At midyear, 85% of the employee population was female, 15% male. Females represented 83.3% of the subjects reporting incidents; males represented 16.7%. These data from a small rural facility differ from many of the findings on the injury experience of health care workers reported in the literature.

Pesticides and their control.

1. Pesticides account for a small but important number of acute human poisonings. 2. When considering interventions for pesticide poisoning in the workplace, interaction may occur on a continuum from a one-to-one encounter to planning or educating in the context of the aggregate. 3. Occupational health nurses need to be aware of the potential harm inherent in human exposure to pesticides and to be prepared to initiate intervention strategies at all phases of injury--pre-event, event, and post-event.

Asbestos review and update.

Concurrent with the widespread use of asbestos in buildings were noticeable increases in the incidence of certain types of lung disease and cancer among workers who mined, milled, manufactured, and applied asbestos containing products. OSHA and EPA initiated efforts to reduce exposure to asbestos in 1971 and 1973, respectively. The approach taken by these agencies can best be understood through knowing the epidemiology of asbestos. The role of the occupational health nurse is centered around prevention of exposure to asbestos by educating employees on the risks of exposure, implementing engineering controls, and enforcing OSHA standards.

Agricultural health nurses. Job analysis of functions and competencies.

Agricultural health nurses address the health and safety issues of farmers, agricultural workers, and farm families. This nurse role incorporates both public health and occupational health nurse specialty practice. The purpose of this study was to describe agricultural health nurse job functions and competencies used in providing services to agricultural populations. A two round modified Delphi technique was used to attain a consensus among participants related to agricultural health nurse functions and competencies. In Round I, a mailed survey assessing demographic characteristics, and job functions and competencies was sent to an identified list of 61 nurses. A second mailed survey, with categorized job function and competency responses elicited through Round I, was sent to the 32 Round I respondents to assess the importance of the job functions and competencies and the frequency of performing each job function. Twenty four Round II surveys were returned. Job functions rated highest were: Serve as a liaison for the agricultural, health and medical, and nonfarm communities. Promote agricultural health and safety issues through the media. Implement educational courses for various groups. Conduct follow up assessment of injury, illness, or disease occurring as a result of an agricultural exposure. Function as a resource for information to victims of agricultural injury and illness and their families. The competencies of greatest importance were interpersonal communication skills, knowledge of injury prevention principles and measures, ability to recognize potential hazards within the work and home environment, and demonstrate a strong sense of self. This study adds to the body of knowledge needed to define the agricultural health nurse role.

Technology enhanced learning for occupational and environmental health nursing: a global imperative.

One strategy for decreasing the barriers to higher education and for increasing the competency and performance of the occupational and environmental health nurse in the information age is technology enhanced learning. Technology enhanced learning encompasses a variety of technologies employed in teaching and learning activities of presentation, interaction, and transmission to on campus and distant students. Web based learning is growing faster than any other instructional technology, offering students convenience and a wealth of information.

Incidence, prevalence, and variables associated with low back pain in staff nurses.

The morbidity, lost work time, and interference with effective work due to low back pain are markedly underestimated when only employee health service data are used. Injured subjects averaged more years of generic, orthopedic, and rehabilitation nursing experience than the non-injured group. Of the studied nurses who experienced work related low back pain within the past 6 months, 78% did not report it to management. More attention should be given to adequate staff availability for shared lifting activities, better design and use of mechanical lifting aids, and further research in how to safely perform tasks from the side of the bed.

Crafting strategy: a constituency plan for the future.

1. The difference in planning and crafting strategy is the level of involvement in the process. It is the crafting of strategy that requires the involvement of state and local constituencies. 2. Creating vision enables constituencies to clarify and realize what they really want, independently of what presently seems possible at the state or local level. 3. By developing an ideal reality or vision first, a bridge can be built between the current and desired organization without loss of purpose. The purpose of the organization is defined by AAOHN's Mission Statement. 4. The bridge is built by using a decision making process similar to the nursing process.

Form follows function. Occupational health nursing as a member of the management team.

Role, often designated by a given title, e.g., manager, has been one of the most common means of defining occupational health nursing practice. A function based model provides an opportunity to reframe the occupational health nurse as a member of the management team. This descriptive study characterized the functions of a random sample (40%) of members of the American Association of Occupational Health Nurses from eight Midwestern states (463) in 1994. With a 78% response rate, the most frequently performed function for all respondents was "evaluate status of employees returning to work after absence" (68%). The relative frequencies for functions performed by the associates degree nurses were very similar to those for diploma nurses (r = .889 based on a perfect relationship value of 1). Subjects with baccalaureates in nursing performed more educational programming than subjects with non-nursing baccalaureates who performed more frequently in a policy area. Type of masters preparation represented different functional activities. The department to which the respondent reported affected functions. Reviewing function by salary level revealed a linear relationship with certain functions by frequency. To facilitate the investigation of the role construct based on functions, the researchers conducted a principle components analysis of the data. Four principle components were found representing groups of functions that tended to be performed by the same sets of respondents. The functions in each component tended to cluster around common skills as defined by Hersey (1988).

Credentialing. Concerns and issues affecting occupational health nursing.

1. Mechanisms for credentialing affecting occupational health nursing include licensure and certification of individuals and accreditation of educational and health care organizations. 2. Issues of control of entry into practice, geographic mobility, and whether licensure will be single or two tiered, national or institutional, are currently under debate. 3. The purpose of certification is to acknowledge the individual and assure the public that the individual has mastered a body of knowledge of a particular specialty. 4. The purpose of accreditation is to evaluate the performance of a service (i.e., education or health care) and to provide consumers of that service necessary information on which to base decisions on use of the services. 5. Occupational health nurses must participate actively in the process of credentialing clarification and reform to be prepared to advance the specialty and respond to the health care needs of the working population in the 21st century.

The impact of educational research centers on occupational health and safety alumni competence. A program evaluation.

1. A 10 step method for program evaluation can be used to evaluate the success of a program in meeting its major goals and objectives. This evaluation examined the 20 year impact of the Midwest Center for Occupational Health and Safety, a NIOSH supported Educational Research Center, on its alumni. 2. The majority of alumni (89%) reported the primary focus of their work after graduation was the provision of occupational and environmental health and safety products and services--consistent with the legislative intent of Educational Research Centers (ERC). 3. Alumni reported the most highly valued ERC products and services included interdisciplinary interactions during and after graduate school, research training, and the presence of the ERC as a regional focal point for occupational health and safety graduate and continuing education. 4. The program evaluation design and survey instrument employed in this study are recommended for adaptation by other ERCs or educational programs faced with the challenge of providing evaluation data with minimal resources.

Minnesota workplace drug testing. Analysis of policy and procedures.

1. An employer's decision whether to drug test or not was found to correlate with the size of the company and how extensively the employer perceives a drug abuse problem exists among its work force. 2. A company's drug testing program must be designed, implemented, and evaluated within a medical-legal framework. This includes issues of: confidentiality, employee actions that trigger a drug test, the presence of a drug and alcohol policy, communicating the program to employees and unions, the employee's rights, the consequences of an employee's positive drug test, and the procedures to be followed when collecting a specimen. 3. Future studies need to explore the issue of dealing with job performance problems; in particular, the cost and effectiveness of employee drug testing vs. the use of discipline alone.