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1.
J Hum Nutr Diet ; 34(1): 115-123, 2021 02.
Article in English | MEDLINE | ID: mdl-32885486

ABSTRACT

BACKGROUND: Healthcare placements in dietetics education contribute significantly to student learning. Exploring students' self-conceptualisation of placement experiences may provide insights to better support learning. Self-determination theory (SDT) has been used to seek insight into clinical and educational settings but has not yet been applied to dietetic placement learning. The present study investigated dietetics students' reflections of key influences on placement learning experiences and their alignment with an SDT framework. METHODS: A post-placement two-stage critical incident debrief was conducted with seven successive cohorts (168 students) of dietetic undergraduate students on final placement. In debriefs, students' anonymous themes were collected and discussed, inductively analysed, and then mapped against an SDT framework of psychological and motivational constructs. RESULTS: Nine key themes were identified that impacted upon placement experiences. Four themes related to framework constructs: (1) Supervisor (and Peer) Autonomy Support; (2) Perceived Competence; (3) Relatedness; and (4) Autonomy and Intrinsic Motivation. Non-SDT themes were also present, including: (5) Learning Environment and Experience; as well as themes about professional behaviours and identity: (6) Teamwork and Interactions; (7) Managing Emotions and Self-Care; (8) Dietetic Communications and Behaviours; and (9) Developing a Professional Identity. CONCLUSIONS: Embedding a structured debrief in the curriculum and using a psychological motivational SDT framework to analyse themes arising can provide valuable information about the learning needs of students on placement with potential for wider application in dietetic learning and teaching and workforce employability. The current findings may have application in university curricula before and after professional placement.


Subject(s)
Dietetics/education , Preceptorship , Students, Health Occupations/psychology , Curriculum , Female , Humans , Learning , Male , Psychological Theory , Qualitative Research
2.
J Hum Nutr Diet ; 32(2): 259-266, 2019 04.
Article in English | MEDLINE | ID: mdl-30604495

ABSTRACT

BACKGROUND: Primary healthcare dietitians have a vital role to play in the prevention and management of chronic disease. Working in primary care requires efficient and effective management of practice to ensure client and practitioner needs are met. The present study aimed to explore the way in which primary care dietitians in Australia view the constructs of efficiency and effectiveness within the context of their practice. METHODS: The study used an exploratory qualitative design within a pragmatist framework. Individual semi-structured telephone interviews were conducted with Australian primary care dietitians. All interviews were audio-recorded, transcribed verbatim and analysed using an inductive thematic approach. RESULTS: Twenty dietitians (17 females) working as private practitioners in primary care from three Australian states participated in the present study. Three themes emerged from the data. The first theme revealed that seeking efficiency and especially effectiveness were important to primary care dietitians and that there was a tension between the two. The second theme identified that efficiency and effectiveness are influenced by personal and structural factors. The final theme explored how dietitians are actively seeking ways to be more efficient and effective, including supportive networks, as well as the utilisation of technology. CONCLUSIONS: Achieving a balance between efficiency and effectiveness in primary care dietetics is challenging to practitioners, who may require further training and support to enhance productivity, time management and resource utilisation. Structured issues exist for the workface. Further studies are required to quantify these findings and to explore whether it is possible to optimise efficiency and effectiveness and achieve sustainability of the dietetic workforce in primary care.


Subject(s)
Clinical Competence , Dietetics/methods , Nutritionists/psychology , Primary Health Care/methods , Work/psychology , Adult , Australia , Chronic Disease/prevention & control , Efficiency , Female , Humans , Male , Middle Aged , Qualitative Research , Workplace/psychology
3.
J Hum Nutr Diet ; 31(1): 47-57, 2018 02.
Article in English | MEDLINE | ID: mdl-29171120

ABSTRACT

BACKGROUND: High-quality research methodologies and clear reporting of studies are essential to facilitate confidence in research findings. The aim of the present study was to conduct an in-depth examination of the methodological quality and reporting of studies included in a recent systematic review of dietitians' effectiveness at providing individualised nutrition care to adult patients. METHODS: The methodological quality and reporting of 27 Randomised Controlled Trials (RCTs) were appraised using the UK Medical Research Council (MRC) Guidelines for complex interventions and the CONSORT checklist for reporting RCTs. A quality appraisal checklist was developed for each guideline/assessment tool aiming to evaluate the extent to which each study met the designated criteria. Excerpts from studies that best addressed criteria were collated to provide exemplary accounts of how criteria may be achieved in future studies. RESULTS: None of the reviewed studies met more than half of the MRC Guidance criteria, indicating that there is clear room for improvement in reporting the methodological underpinnings of these studies. Similarly, no studies met all criteria of the CONSORT checklist, suggesting that there is also room for improvement in the design and reporting of studies in this field. CONCLUSIONS: Dietitians, researchers and journal editors are encouraged to use the results and exemplary accounts from this review to identify key aspects of studies that could be improved in future research. Improving future research will enhance the quality of the evidence-base that investigates the outcomes of dietary interventions involving dietitians.


Subject(s)
Dietetics , Guideline Adherence , Health Services Research/standards , Nutritionists , Primary Health Care , Research Design , Humans
4.
J Hum Nutr Diet ; 30(5): 588-595, 2017 10.
Article in English | MEDLINE | ID: mdl-28464296

ABSTRACT

BACKGROUND: Student confidence is an important contributor to a successful professional placement experience. The present study aimed to evaluate a placement preparation program for student dietitians and to assess the impact on self-rated confidence with respect to commencing placements. METHODS: The present study is part of a design-based research approach that involves students in a cyclic enquiry to evaluate and improve curricula. Nutrition and Dietetics students at an Australian university participated in a 1-week mandatory workshop - Pre-Placement week (PrePW), N = 98 students: in 2015 (n = 54) and 2016 (n = 44). An online survey was conducted before and after PrePW using a five-point Likert scale (1 = not confident; 5 = very confident) to assess self-rated confidence to commence placements. Mean (SD) scores were calculated. Paired and independent t-tests evaluated within- and between-group differences, respectively. RESULTS: Before PrePW, the mean (SD) for student confidence to commence placements overall (in all areas of practise) was 'somewhat confident' [2.9 (0.6) in 2015 and 3.0 (0.7) in 2016]. Students were least confident to commence Clinical Practice [2015: 2.5 (0.6); 2016: 2.8 (0.6)] compared to Food Service Management (FSM) [2015: 3.2 (0.9); 2016: 3.1 (0.9)] and Community and Public Health Nutrition (CPHN) [2015: 3.3 (0.9); 2016: 3.2 (0.8)]. Student feedback from PrePW 2015 was used to change the curriculum and PrePW program. The 2016 students reported significantly greater confidence within all areas of practice: Clinical Practice [3.4 (0.6)], FSM [3.7 (0.6)] and CPHN [3.8 (0.6)], including confidence to commence placements overall [3.6 (0.6)] (P < 0.05). CONCLUSIONS: Design-based research provides a useful framework for improvement to curricula and, in this case, was successful in enhancing student confidence in preparation for professional placement.


Subject(s)
Dietetics/education , Nutritionists/education , Professional Competence , Students, Health Occupations/psychology , Australia , Cohort Studies , Curriculum , Education, Professional , Exercise , Food Services , Humans , Life Style , Nutrition Assessment , Nutritionists/psychology , Surveys and Questionnaires
5.
J Hum Nutr Diet ; 30(3): 378-384, 2017 06.
Article in English | MEDLINE | ID: mdl-27709690

ABSTRACT

BACKGROUND: Nutrition studies in patients admitted to hospital frequently disregard oral intake because measurement is time-intensive and logistically challenging. In free-living populations, weighed food records (WFR) are the gold-standard and are conducted on weekend and weekdays to capture variations in intake, although this may not translate during hospitalisation. The present study aimed to determine whether oral intake differs between weekends and weekdays in hospitalised patients. METHODS: For adult patients initially admitted to the intensive therapy unit with a moderate-severe head injury over a 12-month period, WFR were conducted each week on Tuesday, Thursday and Saturday throughout hospitalisation. Meal components were weighed before and after consumption, and energy and protein intakes were calculated using specialised software. Data are reported as the mean (SD). Differences were assessed using paired t-tests and agreement using Bland-Altman plots. RESULTS: Thirty-two patients had WFR collected on 220 days, 68% (n = 149) on weekdays and 32% (n = 71) on weekends. Overall, daily intakes were 5.72 (3.67) MJ [1367 (877) kcal] and 62 (40) g protein. There were no differences in intake across all days (P = 0.937 energy, P = 0.797 protein), nor between weekdays and weekends, in weeks 1-3 of oral intake (all P > 0.1). Limits of agreement between mean intakes across days were wide for energy [range -11.20 to 9.55 MJ (-2680 to 2283 kcal)] and protein (range -125 to 110 g). CONCLUSIONS: Grouped energy and protein intakes from WFR in hospitalised patients are similar on weekdays and weekends, although large intra-patient variations occur. Future quantification of oral intake during hospitalisation should include as many days as feasible, although not necessarily weekend days, to reflect true intake.


Subject(s)
Diet Records , Time Factors , Adult , Body Mass Index , Critical Illness/therapy , Diet , Female , Hospitalization , Humans , Length of Stay , Male , Meals , Middle Aged , Nutrition Assessment , Prospective Studies
6.
Psychol Med ; 46(7): 1379-90, 2016 May.
Article in English | MEDLINE | ID: mdl-26847689

ABSTRACT

BACKGROUND: Lysergic acid diethylamide (LSD) is a potent serotonergic hallucinogen or psychedelic that modulates consciousness in a marked and novel way. This study sought to examine the acute and mid-term psychological effects of LSD in a controlled study. METHOD: A total of 20 healthy volunteers participated in this within-subjects study. Participants received LSD (75 Āµg, intravenously) on one occasion and placebo (saline, intravenously) on another, in a balanced order, with at least 2 weeks separating sessions. Acute subjective effects were measured using the Altered States of Consciousness questionnaire and the Psychotomimetic States Inventory (PSI). A measure of optimism (the Revised Life Orientation Test), the Revised NEO Personality Inventory, and the Peter's Delusions Inventory were issued at baseline and 2 weeks after each session. RESULTS: LSD produced robust psychological effects; including heightened mood but also high scores on the PSI, an index of psychosis-like symptoms. Increased optimism and trait openness were observed 2 weeks after LSD (and not placebo) and there were no changes in delusional thinking. CONCLUSIONS: The present findings reinforce the view that psychedelics elicit psychosis-like symptoms acutely yet improve psychological wellbeing in the mid to long term. It is proposed that acute alterations in mood are secondary to a more fundamental modulation in the quality of cognition, and that increased cognitive flexibility subsequent to serotonin 2A receptor (5-HT2AR) stimulation promotes emotional lability during intoxication and leaves a residue of 'loosened cognition' in the mid to long term that is conducive to improved psychological wellbeing.


Subject(s)
Affect/drug effects , Hallucinogens/pharmacology , Lysergic Acid Diethylamide/pharmacology , Personal Satisfaction , Receptor, Serotonin, 5-HT2A/drug effects , Adult , Cross-Over Studies , Hallucinogens/administration & dosage , Humans , Lysergic Acid Diethylamide/administration & dosage , Middle Aged , Young Adult
7.
J Hum Nutr Diet ; 29(4): 441-8, 2016 08.
Article in English | MEDLINE | ID: mdl-26879748

ABSTRACT

BACKGROUND: Childhood obesity is becoming more common as Malaysia experiences rapid nutrition transition. Current evidence related to parental influences on child dietary intake and body weight status is limited. The present study aimed to report, among Malay families, the prevalence of energy mis-reporting and dietary relationships within family dyads. METHODS: The cross-sectional Family Diet Study (n = 236) was conducted at five primary schools in central of Peninsular Malaysia. Each family consisted of a Malay child, aged 8-12 years, and their main caregiver(s). Information on socio-demographics, dietary intake and anthropometry were collected. Correlations and regression analyses were used to assess dietary relationships within family dyads. RESULTS: Approximately 29.6% of the children and 75.0% parents were categorised as being overweight or obese. Intakes of nutrients and food groups were below the national recommended targets for majority of children and adults. A large proportion of energy intake mis-reporters were identified: mothers (55.5%), fathers (40.2%) and children (40.2%). Children's body mass index (BMI) was positively associated with parental BMI (fathers, r = 0.37; mothers, r = 0.34; P < 0.01). For dietary intakes, moderate-to-strong (0.35-0.72) and weak-to-moderate (0.16-0.35) correlations were found between mother-father and child-parent dyads, respectively. Multiple regression revealed that maternal percentage energy from fat (Ɵ = 0.09, P < 0.01) explained 81% of the variation in children's fat intake. CONCLUSIONS: Clear parental dietary relationships, especially child-mother dyads, were found. Despite a significant proportion of families with members who were overweight or obese, the majority reported dietary intakes below recommended levels, distorted by energy mis-reporting. The findings of the present study can inform interventions targeting parent-child relationships to improve family dietary patterns in Malaysia.


Subject(s)
Child Nutritional Physiological Phenomena , Diet/adverse effects , Family Health , Feeding Behavior , Food Preferences , Overweight/etiology , Pediatric Obesity/etiology , Body Mass Index , Child , Child Nutritional Physiological Phenomena/ethnology , Cross-Sectional Studies , Diet/ethnology , Energy Intake/ethnology , Family Health/ethnology , Feeding Behavior/ethnology , Female , Food Preferences/ethnology , Health Transition , Humans , Malaysia/epidemiology , Male , Nutrition Surveys , Nutritional Status/ethnology , Overweight/epidemiology , Overweight/ethnology , Parents , Pediatric Obesity/epidemiology , Pediatric Obesity/ethnology , Prevalence , Reproducibility of Results , Self Report
8.
Rural Remote Health ; 12(1): 1923, 2012.
Article in English | MEDLINE | ID: mdl-22506812

ABSTRACT

INTRODUCTION: Rural and remote communities in Australia are typically underserviced by dietitians. The recruitment of dietitians to rural areas has improved in recent years; however, retention remains an issue. Key factors that lead to an increase in funding and the development of more dietetic positions in rural areas are unknown. The purpose of this study was to describe dietetic services in rural areas and to determine the drivers for and barriers to the development of dietetic positions in rural areas. METHODS: A sequential explanatory mixed methods approach was used to examine six case study sites of dietetic service delivery in rural northern New South Wales (NSW) Australia between 1991 and 2006. The six sites represented different models of dietetic service delivery from the study area. Data sources included workforce documents and in-depth individual interviews on position development with 40 key informants, including past and present dietitians, dietetic managers and health service managers. Interview data were thematically analysed with the aid of NVivo7 (www.qsrinternational.com). Themes were coded into common categories, using a constant comparison inductive approach. RESULTS: Forty key informants agreed to participate in the in-depth, semi-structured interview. Participants included 28 dietitians (past and present), three dietetics managers and nine managers. The majority of participants were female (87.5%). Document analysis showed that the dietetic workforce had a 5.6-fold increase across the six sites over the 15 years. Themes that emerged from the interviews indicated that new positions were established through ad hoc and opportunistic funding, a gradual increase in funding or due to concerted efforts by champions advocating for increased funding. CONCLUSION: The findings from this study have important implications for the development of dietetic staffing in rural areas. There is an inconsistent approach to the development of dietetic positions in rural areas of Australia. Factors that inhibited the development of positions included a general lack of funds and competing priorities. A systematic, planned approach to the development of dietetic positions is needed in rural Australia. Champions for the development of positions were effective in increasing positions, particularly when they have management support.


Subject(s)
Dietary Services , Dietetics , Rural Health Services , Australia , Capital Financing/methods , Capital Financing/trends , Dietary Services/economics , Dietary Services/trends , Dietetics/economics , Dietetics/trends , Female , Humans , Interviews as Topic , Male , Medically Underserved Area , New South Wales , Organizational Case Studies , Personnel Selection , Personnel Turnover/trends , Rural Health Services/economics , Rural Health Services/trends , Workforce
9.
Nat Cell Biol ; 3(7): 628-36, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11433294

ABSTRACT

Wnt signalling regulates beta-catenin-dependent developmental processes through the Dishevelled protein (Dsh). Dsh regulates two distinct pathways, one mediated by beta-catenin and the other by Jun kinase (JNK). We have purified a Dsh-associated kinase from Drosophila that encodes a homologue of Caenorhabditis elegans PAR-1, a known determinant of polarity during asymmetric cell divisions. Treating cells with Wnt increases endogenous PAR-1 activity coincident with Dsh phosphorylation. PAR-1 potentiates Wnt activation of the beta-catenin pathway but blocks the JNK pathway. Suppressing endogenous PAR-1 function inhibits Wnt signalling through beta-catenin in mammalian cells, and Xenopus and Drosophila embryos. PAR-1 seems to be a positive regulator of the beta-catenin pathway and an inhibitor of the JNK pathway. These findings show that PAR-1, a regulator of polarity, is also a modulator of Wnt-beta-catenin signalling, indicating a link between two important developmental pathways.


Subject(s)
Caenorhabditis elegans Proteins , Phosphoproteins/metabolism , Protein Serine-Threonine Kinases/physiology , Proto-Oncogene Proteins/physiology , Trans-Activators , Zebrafish Proteins , Adaptor Proteins, Signal Transducing , Amino Acid Sequence , Animals , CHO Cells , Cricetinae , Cytoskeletal Proteins/drug effects , Dishevelled Proteins , Drosophila/embryology , Drosophila Proteins , Humans , JNK Mitogen-Activated Protein Kinases , Mitogen-Activated Protein Kinases/drug effects , Mitogens/physiology , Molecular Sequence Data , Phosphorylation , Protein Binding , Protein Serine-Threonine Kinases/metabolism , Protein Serine-Threonine Kinases/pharmacology , Proto-Oncogene Proteins/drug effects , Proto-Oncogene Proteins/pharmacology , Sequence Alignment , Signal Transduction/drug effects , Transcriptional Activation/drug effects , Tumor Cells, Cultured , Wnt Proteins , Xenopus , Xenopus Proteins , beta Catenin
10.
J Exp Med ; 189(3): 451-60, 1999 Feb 01.
Article in English | MEDLINE | ID: mdl-9927507

ABSTRACT

Secondary lymphoid organ chemokine (SLC) is expressed in high endothelial venules and in T cell zones of spleen and lymph nodes (LNs) and strongly attracts naive T cells. In mice homozygous for the paucity of lymph node T cell (plt) mutation, naive T cells fail to home to LNs or the lymphoid regions of spleen. Here we demonstrate that expression of SLC is undetectable in plt mice. In addition to the defect in T cell homing, we demonstrate that dendritic cells (DCs) fail to accumulate in spleen and LN T cell zones of plt mice. DC migration to LNs after contact sensitization is also substantially reduced. The physiologic significance of these abnormalities in plt mice is indicated by a markedly increased sensitivity to infection with murine hepatitis virus. The plt mutation maps to the SLC locus; however, the sequence of SLC introns and exons in plt mice is normal. These findings suggest that the abnormalities in plt mice are due to a genetic defect in the expression of SLC and that SLC mediates the entry of naive T cells and antigen-stimulated DCs into the T cell zones of secondary lymphoid organs.


Subject(s)
Chemokines, CC/genetics , Chemokines, CC/immunology , Dendritic Cells/immunology , Epidermis/immunology , T-Lymphocytes/immunology , Animals , Antigen Presentation , Cell Movement , Chemokine CCL19 , Chemokine CCL21 , Chemokines, CC/biosynthesis , Chemokines, CC/deficiency , Chemotaxis, Leukocyte , Coronavirus Infections/immunology , Dendritic Cells/cytology , Hepatitis, Viral, Animal/immunology , Immune System/abnormalities , Lymph Nodes/immunology , Mice , Mice, Mutant Strains , Murine hepatitis virus/immunology , Murine hepatitis virus/pathogenicity , RNA, Messenger/isolation & purification , Receptors, CCR7 , Receptors, Chemokine/metabolism , Spleen/immunology , T-Lymphocytes/cytology
11.
Science ; 243(4898): 1564-70, 1989 Mar 24.
Article in English | MEDLINE | ID: mdl-2538922

ABSTRACT

When platelet-derived growth factor (PDGF) binds to its receptor on a quiescent fibroblast or smooth muscle cell, it stimulates a remarkably diverse group of biochemical responses, including changes in ion fluxes, activation of several kinases, alterations in cell shape, increased transcription of a number of genes, and stimulation of enzymes that regulate phospholipid metabolism. These and other reactions culminate, hours later, in DNA replication and cell division. How does the receptor for PDGF recognize and bind its specific ligand and then transduce this signal across the cell membrane via a single membrane-spanning region? Which of the immediate cellular responses are directly involved in the biochemical pathways that lead to DNA synthesis? How does the PDGF receptor trigger a diverse group of responses? Recent studies of the PDGF receptor have provided insight into these issues.


Subject(s)
Platelet-Derived Growth Factor/physiology , Receptors, Cell Surface/physiology , Animals , Binding Sites , Gene Expression Regulation , Humans , Membrane Proteins/physiology , Membrane Proteins/ultrastructure , Molecular Structure , Protein-Tyrosine Kinases/physiology , Receptors, Cell Surface/ultrastructure , Receptors, Platelet-Derived Growth Factor
12.
Science ; 266(5192): 1862-5, 1994 Dec 16.
Article in English | MEDLINE | ID: mdl-7527937

ABSTRACT

Src homology 2 (SH2) domains bind specifically to tyrosine-phosphorylated proteins that participate in signaling by growth factors and oncogenes. A protein domain was identified that bound specifically to the tyrosine-phosphorylated form of its target protein but differs from known SH2 sequences. Phosphotyrosine-binding (PTB) domains were found in two proteins: SHC, a protein implicated in signaling through Ras; and SCK, encoded by a previously uncharacterized gene. The PTB domain of SHC specifically bound to a tyrosine-phosphorylated 145-kilodalton protein. PTB domains are an alternative to SH2 domains for specifically recruiting tyrosine-phosphorylated proteins into signaling complexes and are likely to take part in signaling by many growth factors.


Subject(s)
Adaptor Proteins, Signal Transducing , Adaptor Proteins, Vesicular Transport , Phosphoproteins/metabolism , Proteins/metabolism , Signal Transduction , Tyrosine/analogs & derivatives , 3T3 Cells , Amino Acid Sequence , Animals , Cell Line , Humans , Mice , Molecular Sequence Data , Phosphorylation , Phosphotyrosine , Platelet-Derived Growth Factor/pharmacology , Protein Binding , Protein-Tyrosine Kinases/chemistry , Protein-Tyrosine Kinases/metabolism , Proteins/chemistry , Shc Signaling Adaptor Proteins , Src Homology 2 Domain-Containing, Transforming Protein 1 , Tyrosine/metabolism
13.
Science ; 239(4842): 914-6, 1988 Feb 19.
Article in English | MEDLINE | ID: mdl-2829358

ABSTRACT

Autocrine activation of platelet-derived growth factor (PDGF) receptors is the mechanism of transformation by the v-sis oncogene. Since the addition of PDGF does not transform normal cells, autocrine mechanisms may involve unique pathways of receptor activation. In this study autocrine stimulation of the PDGF receptor was observed in v-sis-transformed normal rat kidney (NRK) cells. In contrast to receptor activation in normal cells, autocrine activation of PDGF receptors in v-sis-transformed cells occurred in intracellular compartments, disrupting receptor processing and diverting receptors and their precursors to a chloroquine-sensitive degradation pathway. These findings show that intracellular activation of receptors by autocrine mechanisms may play a role in cell transformation.


Subject(s)
Oncogenes , Receptors, Cell Surface/metabolism , Ammonium Chloride/pharmacology , Animals , Cell Line, Transformed , Cell Membrane/metabolism , Chloroquine/pharmacology , Half-Life , Hexosaminidases/pharmacology , Immunosorbent Techniques , Molecular Weight , Phosphorylation , Platelet-Derived Growth Factor/pharmacology , Protein Precursors/metabolism , Rats , Receptors, Cell Surface/drug effects , Receptors, Platelet-Derived Growth Factor , Trypsin/metabolism
14.
Science ; 192(4241): 791-3, 1976 May 21.
Article in English | MEDLINE | ID: mdl-4894

ABSTRACT

A radioactively labeled alpha-adrenergic antagonist, [3H]dihydroergocryptine, binds specifically to a site on rabbit uterine membranes. Binding is rapid, reaching equilibrium in less than 17 minutes at 25 degrees C. Adrenergic agonists compete for this binding site with an order of affinities identical to the pharmacological potency order of these agents as alpha-adrenergic agonists (epinephrine greater than norepinephrine greater than isoprotereonl). The (-) stereoisomers of epinephrine and norepinephrine are 30 times more potent in competing for the site than the corresponding (+) stereoisomers. alpha-Adrenergic antagonists, such as phentolamine and phenoxybenzamine, potently compete for the binding sites while the beta-adrenergic antagonist propranolol does not. Structural analogs of catecholamines that are devoid of alpha-adrenergic physiological activity do not compete for [3H]dihydroergocryptine binding sites. These data suggest that alpha-adrenergic receptors can be directly identified and studied by [3H]dihydroergocryptine binding.


Subject(s)
Adrenergic alpha-Agonists/metabolism , Adrenergic alpha-Antagonists/metabolism , Ergoloid Mesylates/metabolism , Receptors, Adrenergic , Animals , Binding, Competitive , Dopamine/metabolism , Female , Kinetics , Propranolol/metabolism , Rabbits , Stereoisomerism , Uterus/metabolism
15.
Science ; 252(5007): 844-8, 1991 May 10.
Article in English | MEDLINE | ID: mdl-1851331

ABSTRACT

A mutated form of the platelet-derived growth factor (PDGF) beta receptor lacking most of its cytoplasmic domain was tested for its ability to block wild-type PDGF receptor function. PDGF induced the formation of complexes consisting of wild-type and truncated receptors. Such complexes were defective in autophosphorylation. When truncated receptors were expressed in excess compared to wild-type receptors, stimulation by PDGF of receptor autophosphorylation, association of phosphatidylinositol-3 kinase with the receptor, and calcium mobilization were blocked. Thus, a truncated receptor can inactivate wild-type receptor function by forming ligand-dependent receptor complexes (probably heterodimers) that are incapable of mediating the early steps of signal transduction.


Subject(s)
Receptors, Cell Surface/antagonists & inhibitors , Signal Transduction/physiology , Animals , Cells, Cultured , Centrifugation, Density Gradient , Cricetinae , In Vitro Techniques , Ligands , Mice , Mice, Inbred BALB C , Phosphorylation , Platelet-Derived Growth Factor , Receptors, Cell Surface/physiology , Receptors, Platelet-Derived Growth Factor
16.
Science ; 234(4780): 1117-9, 1986 Nov 28.
Article in English | MEDLINE | ID: mdl-3465038

ABSTRACT

The bombesin-like peptides are potent mitogens for Swiss 3T3 fibroblasts, human bronchial epithelial cells, and cells isolated from small cell carcinoma of the lung. The mechanism of signal transduction in the proliferative response to bombesin was investigated by studying the effect of Bordetella pertussis toxin on bombesin-stimulated mitogenesis. At nanomolar concentrations, bombesin increased levels of c-myc messenger RNA and stimulated DNA synthesis in Swiss 3T3 cells. Treatment of the cells with pertussis toxin (5 nanograms per milliliter) completely blocked bombesin-enhanced c-myc expression and eliminated bombesin-stimulated DNA synthesis. This treatment had essentially no effect on the mitogenic responses to either platelet-derived growth factor or phorbol 12,13-dibutyrate. These results suggest that the mitogenic actions of bombesin-like growth factors are mediated through a pertussis toxin-sensitive guanine nucleotide-binding protein. Furthermore they indicate that bombesin-like growth factors act through pathways that are different from those activated by platelet-derived growth factor.


Subject(s)
Bombesin/pharmacology , DNA, Neoplasm/biosynthesis , Oncogenes/drug effects , Pertussis Toxin , Virulence Factors, Bordetella/pharmacology , Animals , Cells, Cultured , Humans , Mice , Phorbol 12,13-Dibutyrate , Phorbol Esters/pharmacology , Platelet-Derived Growth Factor/pharmacology
17.
Science ; 268(5214): 1177-9, 1995 May 26.
Article in English | MEDLINE | ID: mdl-7539155

ABSTRACT

Src homology 2 (SH2) domains mediate assembly of signaling complexes by binding specifically to tyrosine-phosphorylated proteins. A phosphotyrosine binding (PTB) domain has been identified which also binds specifically to tyrosine-phosphorylated targets, but is structurally different from SH2 domains. Expression cloning was used to identify targets of PTB domains. PTB domains bound to phosphotyrosine within a sequence motif, asparagine-X1-X2-phosphotyrosine (where X represents any amino acid), that is found in many signaling proteins and is not recognized by SH2 domains. Mutational studies indicated that high affinity binding of PTB domains may require a specific conformation of the motif.


Subject(s)
Phosphopeptides/metabolism , Protein Binding/physiology , Signal Transduction/physiology , Tyrosine/analogs & derivatives , Amino Acid Sequence , Binding Sites/physiology , Binding, Competitive , Cell Line , Humans , Molecular Sequence Data , Phosphotyrosine , Recombinant Proteins/metabolism , Tumor Cells, Cultured , Tyrosine/metabolism
18.
Science ; 271(5250): 808-10, 1996 Feb 09.
Article in English | MEDLINE | ID: mdl-8628997

ABSTRACT

Genetic studies indicated that the Drosophila melanogaster protein REAPER (RPR) controls apoptosis during embryo development. Induction of RPR expression in Drosophila Schneider cells rapidly stimulated apoptosis. RPR-mediated apoptosis was blocked by N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk), which suggests that an interleukin-1 beta converting enzyme (ICE)-like protease is required for RPR function. RPR-induced apoptosis was associated with increased ceramide production that was also blocked by Z-VAD-fmk, which suggests that ceramide generation requires an ICE-like protease as well. Thus, the intracellular RPR protein uses cell death signaling pathways similar to those used by the vertebrate transmembrane receptors Fas (CD95) and tumor necrosis factor receptor type 1.


Subject(s)
Apoptosis , Ceramides/metabolism , Cysteine Endopeptidases/metabolism , Drosophila Proteins , Drosophila melanogaster/cytology , Peptides/physiology , Amino Acid Chloromethyl Ketones/pharmacology , Amino Acid Sequence , Animals , Apoptosis/drug effects , Caspase 1 , Cell Line , Ceramides/pharmacology , Copper/pharmacology , Copper Sulfate , Drosophila melanogaster/embryology , Drosophila melanogaster/genetics , Drosophila melanogaster/metabolism , Enzyme Activation , Gene Expression , Molecular Sequence Data , Peptides/genetics , Protease Inhibitors/pharmacology , Signal Transduction , Transfection
19.
Science ; 243(4895): 1191-4, 1989 Mar 03.
Article in English | MEDLINE | ID: mdl-2466336

ABSTRACT

The molecules with which the platelet-derived growth factor (PDGF) receptor interacts to elicit the biochemical reactions responsible for cell proliferation have not been identified. Antisera directed against specific PDGF receptor peptides coprecipitated a phosphatidylinositol (PI) kinase and the PDGF receptor. Immunoprecipitates from PDGF-stimulated cells contained 10 to 50 times as much PI kinase as those from unstimulated cells. Mutation of the PDGF receptor by deletion of its kinase insert region resulted in a receptor markedly less effective than the wild type in eliciting cell proliferation and defective in PDGF-stimulated PI kinase, but still capable of PDGF-induced receptor autophosphorylation and phosphoinositide hydrolysis. These data show that the PDGF receptor is physically associated with a PDGF-sensitive PI kinase that is distinct from tyrosine kinase and is not required for PDGF-induced PI hydrolysis. The finding that the mutant PDGF receptor missing the kinase insert domain elicited known early biochemical responses to PDGF, but did not associate with or regulate PI kinase, suggests a novel role for the receptor-associated PI kinase in the transmission of mitogenic signals.


Subject(s)
Phosphotransferases/metabolism , Receptors, Cell Surface/metabolism , Signal Transduction , 1-Phosphatidylinositol 4-Kinase , Animals , Cell Line , Chromatography , Cricetinae , Immunoassay , Immunosorbent Techniques , Mice , Mice, Inbred BALB C , Mutation , Phosphatidylinositols/metabolism , Phosphorylation , Phosphotyrosine , Platelet-Derived Growth Factor/pharmacology , Protein-Tyrosine Kinases/metabolism , Receptors, Cell Surface/genetics , Receptors, Platelet-Derived Growth Factor , Tyrosine/analogs & derivatives , Tyrosine/metabolism
20.
Science ; 268(5207): 100-2, 1995 Apr 07.
Article in English | MEDLINE | ID: mdl-7701328

ABSTRACT

Phosphatidylinositol (Pl)-3 kinase is one of many enzymes stimulated by growth factors. A constitutively activated mutant, p110, that functions independently of growth factor stimulation was constructed to determine the specific responses regulated by Pl-3 kinase. The p110 protein exhibited high specific activity as a Pl-3 kinase and as a protein kinase. Expression of p110 in NIH 3T3 cells induced transcription from the fos promoter. Co-expression of dominant negative Ras blocked this response. When expressed in Xenopus laevis oocytes, p110 increased the amount of guanosine 5'-triphosphate-bound Ras, caused activation of the Ras effector Raf-1, and induced Ras-dependent oocyte maturation. These findings show that Pl-3 kinase can stimulate diverse Ras-dependent cellular processes, including oocyte maturation and fos transcription.


Subject(s)
Phosphotransferases (Alcohol Group Acceptor)/physiology , Signal Transduction/physiology , ras Proteins/physiology , 3T3 Cells , Animals , Genes, fos/genetics , Mice , Phosphatidylinositol 3-Kinases , Phosphotransferases (Alcohol Group Acceptor)/biosynthesis , Promoter Regions, Genetic/physiology , Recombinant Fusion Proteins/biosynthesis , Transcription, Genetic/physiology , Xenopus laevis
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