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Biomedical subjects

J M Roper

Publications and source records attributed to J M Roper.

13 recordsLinked to original sources
PubMed1997

A single precursor protein for ferrochelatase-I from Arabidopsis is imported in vitro into both chloroplasts and mitochondria.

Ferrochelatase is the last enzyme of heme biosynthesis and in higher plants is found in both chloroplasts and mitochondria. We have isolated cDNAs for two isoforms of ferrochelatase from Arabidopsis thaliana, both of which are imported into isolated chloroplasts. In this paper we show that ferrochelatase-I is also imported into isolated pea mitochondria with approximately the same efficiency as into chloroplasts. Processing of the precursor was observed with both chloroplast stroma and mitochondrial matrix extracts. This was inhibited by EDTA, indicating it was due to the specific processing proteases. The specificity of import was verified by the fact that the mitochondrial preparation did not import the precursor of the light-harvesting chlorophyll a/b protein precursor or the precursor of porphobilinogen deaminase, an earlier enzyme of tetrapyrrole biosynthesis, both of which are exclusively chloroplast-located. Furthermore, import of ferrochelatase-I precursor into mitochondria was inhibited by valinomycin, but this had no effect on its import into chloroplasts. Thus a single precursor molecule is recognized by the import machinery of the two organelles. The implications for the targeting of ferrochelatase in a possible protective role against photooxidative stress are discussed.

Arabidopsis↗
PubMed1997

Molecular localisation of ferrochelatase in higher plant chloroplasts.

Within the chloroplast of higher plants, a crucial branchpoint of the tetrapyrrole synthesis pathway is the chelation of either Fe2+ to make haem, or Mg2+ for chlorophyll, catalysed by ferrochelatase or magnesium chelatase, respectively. One model that has been proposed for the control of this branchpoint, based on biochemical studies, is that the two enzymes are spatially separated within the chloroplast, ferrochelatase being exclusively in the thylakoids, while magnesium chelatase is associated with the envelope [Matringe, M., Camadro, J.-M., Joyard, J. & Douce, R. (1994) J. Biol. Chem. 269, 15010-15015]. We have used a sensitive molecular method to investigate this possibility. Radiolabelled precursor proteins for ferrochelatase from Arabidopsis have been imported into isolated chloroplasts. Their distribution in the different subchloroplastic fractions have then been determined, and compared with that for light-harvesting chlorophyll protein, which is exclusively thylakoidal, and the envelope-located phosphate translocator. Clear evidence for the specific association of ferrochelatase protein with both thylakoid and envelope membranes has been obtained, thus suggesting strongly that the control of the branchpoint cannot be by spatial separation of the two chelatases.

Arabidopsis↗
PubMed1997

The reality of political ethical conflicts. Nurse manager dilemmas.

Losing sleep and deciding your administrative job is not worth the pressures you feel could be symptoms that you are struggling with a political ethical conflict. The authors describe a variety of political ethical conflicts and how they can arise, giving examples of dilemmas experienced by nurse managers and offering suggestions for developing successful coping strategies.

Aged↗
PubMed1995

Isolation, characterisation and expression of a cDNA clone encoding plastid aspartate aminotransferase from Arabidopsis thaliana.

A clone encoding aspartate aminotransferase (AAT, EC 2.6.1.1) was isolated from an Arabidopsis thaliana leaf cDNA library. This clone contains a 1365 bp open reading frame encoding a polypeptide of 49.8 kDa, designated Ataat1. The clone was shown to contain a chloroplastic isoenzyme as an in organellar protein import assay demonstrated that a radiolabelled transcription/translation product of 49.8 kDa was imported into viable pea chloroplasts and was subsequently processed to yield a mature protein of 45 kDa. The open reading frame corresponding to the predicted mature AAT was manipulated into an expression construct (pEC14). Transformed Escherichia coli cells containing pEC14 expressed up to 16 times more AAT activity than vector only controls, thus demonstrating conclusively that the clone encoded AAT.

Amino Acid Sequence↗
PubMed1994

Isolation of a cDNA encoding chloroplast ferrochelatase from Arabidopsis thaliana by functional complementation of a yeast mutant.

Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX to form protoheme. It is located in the mitochondria in all eukaryotes and is also found in plastids in plants. Although it has been purified from animals and microorganisms, and genes for it isolated and characterized, very little is known about plant ferrochelatases. We have isolated a cDNA for ferrochelatase from the higher plant Arabidopsis thaliana by functional complementation of a mutant of Saccharomyces cerevisiae defective in this enzyme. The cDNA encodes a protein of 52 kDa, which has 25-35% sequence similarity to ferrochelatases from other organisms. There is an N-terminal extension of about 65 residues, which is almost certainly the chloroplast transit peptide, since the precursor protein, transcribed and translated in vitro, is efficiently imported and processed to the mature size by isolated pea chloroplasts. In contrast, the precursor was not processed by mitochondrial processing peptidase activity, nor could import into isolated yeast mitochondria be demonstrated conclusively, although, presumably, in the rescued yeast mutant, at least some of the Arabidopsis ferrochelatase must be present in the mitochondria. A single transcript the same size as the cDNA was detected in both Arabidopsis leaves and roots, although the amount of message was greater in the photosynthetic tissue. Southern analysis suggests that there is a single gene for chloroplast ferrochelatase in Arabidopsis.

Amino Acid Sequence↗
PubMed1994

The homicidal patient: when a plan of care violates standards of care.

1. The nursing care of an extraordinarily dangerous patient may necessitate implementing a treatment plan that should never be used under normal circumstances. 2. The subject whose case is described in this article presented management problems that required a plan violating accepted standards of care. 3. Although ultimately successful, the plan's restrictive mode (and the stress of coping with this patient) wearied nursing staff members and caused divisions among the staff and multidisciplinary team.

Adult↗
PubMed1991

The interactional dynamics of violence, Part I: An acute psychiatric ward.

The purpose of the following two articles is to shift the emphasis from a strictly patient-centered focus to an interaction-centered focus. Evidence from independent research projects in two different patient care settings demonstrates the interactional nature of violent behavior. One project was conducted on an acute adult psychiatric inpatient unit; the other project was conducted in a juvenile detention facility. Each of these articles describes one segment from two separate and independent parent research projects. Although these clinical research projects were conducted in two very different clinical facilities with very different patient populations, the researchers subsequently discovered common categories and themes regarding the issues of control and the interactional dynamics of violence in the two studies. Interactions between health care providers and patients in the acute psychiatric setting resembled the corresponding interactions in the juvenile detention setting. Both populations had been deprived of power, and all patients/adolescents had some restrictions on their freedom with few choices and opportunities to display positive conduct. Furthermore, the environment in each setting was structured according to the needs of the staff/caretakers, who assumed some degree of control over the individuals in the population being served. Labeling and control issues were identified in the findings from both studies. In the two articles that follow, the specific qualitative research methods used in each study are described. Common themes are discussed from each clinical perspective, using research data and case examples that exemplify the interactional basis of violent behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗
PubMed1991

Agitation in the demented patient. A framework for management.

The inability to manage agitation has led to institutionalization of the patient by the family, overuse of physical restraints, and inappropriate use of psychotropic medication, all of which confound the behavior of the demented individual. It is not only the behavior of the patient but also the interpretation of that behavior that is critically important in the successful management of agitation. Caregivers must be careful to assess their own reactions and responses to patient behaviors before actions are taken that may not lessen agitation but increase the frequency and intensity of patient action.

Aged↗
PubMedDate not supplied

Removal from stimuli for crisis intervention: using least restrictive methods to improve the quality of patient care.

The use of seclusion or seclusion and restraints (S/SR) may affect patients negatively, even if controlling their behavior in the short run, by placing them in the "victim" role and fostering a corrosive atmosphere of patient-caregiver mistrust and alienation. This project's goal was to reduce the use of the most restrictive measures by increasing the use of the less restrictive removal from stimuli (RFS). Verbally and even physically threatening patients in a psychiatric intensive care unit were removed from stimuli if their behaviors were not sustained and they ultimately cooperated with staff. RFS was deemed successful when a patient did not need more restrictive measures following its use. The data for this study were obtained by tabulating RFS and S/SR utilization rates for a year. Frequencies, measures of variance, ratios, and t ratios were used to analyze the data. The use of RFS and other nonrestrictive measures to reduce patient stress and frustration resulted in decreased utilization of seclusion and restraints. The frequency and severity of negativistic, aggressive behaviors of patients were also observed to have diminished.

Analysis of Variance↗
PubMedDate not supplied

Research in psychiatry: increasing staff knowledge and experience.

In a large psychiatric inpatient facility, a course on writing a research proposal was developed in response to nurses' requests to learn about conducting research. The research course was provided to a cross-section of registered nurses with a variety of education and experience backgrounds. The goal was the development of a proposal by each student by the end of the eight classes. The success of this first course was attributed to RN/instructor enthusiasm, support from nursing administration, and the ability to continue mentoring of RNs as they conducted their studies.

Education, Nursing, Continuing↗