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Bosio PM, Cannon S, McKenna PJ, O'Herlihy C, Conroy R, Brady H. Plasma P-selectin is elevated in the first trimester in women who subsequently develop pre-eclampsia. BJOG 2001; 108:709-15. [PMID: 11467696 DOI: 10.1111/j.1471-0528.2001.00170.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To report plasma concentrations of the adhesion cell molecule P-selectin during pregnancy to determine the effect of subsequent development of hypertension and pre-eclampsia. DESIGN A longitudinal study. METHODS A longitudinal study involving 70 women followed up from early pregnancy; 20 who subsequently developed pre-eclampsia were compared with 24 who developed gestational hypertension and 26 normotensive women with normal obstetric outcome. The determination of citrate plasma soluble P-selectin levels throughout pregnancy was performed using a commercial quantitative sandwich immunoassay kit. The temporal course of plasma P-selectin in the three groups of subjects was analysed. RESULTS There was no significant difference in mean plasma P-selectin concentration between normotensive and gestational hypertensive subjects at any stage of pregnancy. Using a cutoff level of 60 ng/mL, P-selectin concentration at 10-14 weeks had a negative predictive value for pre-eclampsia of almost 99%. Mean plasma P-selectin concentrations were significantly elevated by 10-14 weeks in women who later developed pre-eclampsia (P < 0.001). CONCLUSIONS Our data support an inflammatory model for pre-eclampsia whereby endothelial cell activation may be secondary to a primary inflammatory response. Plasma P-selectin has significant potential as a first trimester clinical marker of pre-eclampsia.
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Abstract
AIMS OF THE STUDY The first aim of the study was to identify the self-assessed support needs of women with breast cancer at various points of illness and, secondly, to establish if these needs formed clusters which could provide the basis for developing a standardized scale of needs for use by breast care teams in the evaluation of care. BACKGROUND It has been found that support given to women with breast cancer has a positive effect upon their reactions to the illness and may even prolong their survival. Given that breast cancer affects a large number of women it is obviously important that those affected receive, in addition to the best available medical treatment, the type of support that best meets their needs. This study aimed to provide information on the impact of breast cancer and the need for various types of support by examining women's own assessment of their needs at different stages of their illness. DESIGN AND METHODS A purposive sample of 12 women with a diagnosis of breast cancer was selected in one health authority in England, United Kingdom (UK). Women selected represented a wide age range (between 26 and 58), were married or in long-term cohabiting relationships and were at different points on the illness trajectory. Women were invited to take part in a semi-structured interview about their experiences of breast cancer. The data from these interviews were analysed using the software package Qualitative Solutions and Research, Nonnumerical Data Indexing, Searching and Theorizing (QSR*NUDIST). Following this content analysis, a questionnaire was formulated which divided statements into seven categories: diagnosis, treatment, support, femininity and body image, family and friends, information and after care, to be rated on a Likert scale ranging from "of no importance" to "extremely important". Questionnaire data were analysed by means of a one-way analysis of variance (for three independent variables) or t-test for two independent variables. Results. The questionnaire was sent to 971 women and achieved a response rate of 50.4%. The mean score for statements of need reached the level of point 4 on the Likert scale (important) with three exceptions: having professional help with family problems and domestic upheaval, coping with feelings of anger and dealing with the question "why me?" CONCLUSION With the above three exceptions, women experienced a high level of need associated with a diagnosis of breast cancer. Studies of this kind should enable resources to be targeted to areas of highest need.
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Lindop E, Cannon S. Experiences of women with a diagnosis of breast cancer: a clinical pathway approach. Eur J Oncol Nurs 2001; 5:91-9. [PMID: 12849036 DOI: 10.1054/ejon.2000.0116] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The study presented in this paper formed the first part of a large survey of breast cancer patients in one health authority in England, UK looking at individual needs expressed by women with a diagnosis of breast cancer. The paper provides an account of the experiences of 12 women with a diagnosis of breast cancer. The women represent a wide age range and different stages of illness. The transcribed accounts of the women were analysed by means of Qualitative Solutions and Research, Non-Numerical Unstructured Data Indexing Searching and Theorising (QSR*NUDIST). The study examined the individual experiences of women with a diagnosis of breast cancer and its aftermath as they passed through different stages related to it. The women's experiences are presented within the conceptual framework of the clinical pathway and their accounts represent their journey along the pathway. Various significant points in this journey are portrayed representing the women's reactions to diagnosis, treatment, femininity and body image, support, family and friends, information and after care.
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Pitts MK, Cannon S, Johnson I, Singh G, Clarke T, Rahman Q. Can we predict who will return to a genitourinary clinic? Int J STD AIDS 2001; 12:346-7. [PMID: 11368811 DOI: 10.1258/0956462011923075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
One hundred and eighty-eight first-time attenders at a genitourinary (GU) clinic were monitored to establish who returned following discharge after treatment. Thirty-six (19%) returned within 2 years with a new infection. The re-attenders did not differ significantly from the rest of the cohort by age, gender or occupation, nor did they differ in their sexual history and psychological variables. Re-attenders were significantly more likely to have consulted their general practitioner (GP) in the 6 months prior to their first clinic attendance.
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Lindop E, Cannon S. Support for patients with breast cancer: evaluation of needs. Eur J Oncol Nurs 2000; 4:179-81. [PMID: 12849650 DOI: 10.1054/ejon.2000.0049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Pitts MK, Woolliscroft J, Cannon S, Johnson I, Singh G. Factors influencing delay in treatment seeking by first-time attenders at a genitourinary clinic. Int J STD AIDS 2000; 11:375-8. [PMID: 10872910 DOI: 10.1258/0956462001916083] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We examined treatment-seeking behaviours amongst a consecutive sample of 188 first-time attenders at a busy genitourinary (GU) clinic in a general hospital. Participants were interviewed and completed a battery of questionnaires prior to receiving diagnosis or treatment. Delay in treatment seeking was measured in 3 ways: utilization delay, illness behaviour delay and appraisal delay. Appraisal delay and illness behaviour were significantly related, but were unrelated to utilization delay. Substantial delays were reported before seeking treatment, with a median of 30 days elapsing between first noticing symptoms and attending the clinic. Analysis of age groups indicated that the oldest groups--45 and above were likely to delay longest, on all 3 measures of delay.
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Jackson RW, Osborne K, Barnes G, Jolliff C, Zamani D, Roll B, Stillings A, Herzog D, Cannon S, Loveland S. Multiregional evaluation of the SimPlate heterotrophic plate count method compared to the standard plate count agar pour plate method in water. Appl Environ Microbiol 2000; 66:453-4. [PMID: 10618266 PMCID: PMC91848 DOI: 10.1128/aem.66.1.453-454.2000] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A new SimPlate heterotrophic plate count (HPC) method (IDEXX Laboratories, Westbrook, Maine) was compared with the pour plate method at 35 degrees C for 48 h. Six laboratories tested a total of 632 water samples. The SimPlate HPC method was found to be equivalent to the pour plate method by regression analysis (r = 0. 95; y = 0.99X + 0.06).
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Abstract
A 30-year-old man with a 7-month history of mild sacral pain and intermittant left sciatica was found to have an expansile lesion in the sacrum on a plain radiograph. Biopsy confirmed a chondromyxoid fibroma which was removed surgically. A 1-year follow-up showed no recurrence. The case is the fifth to be reported. Plain film and MRI appearances, histology and treatment are described. The previously reported cases are reviewed and the current literature is discussed.
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Shankar AG, Pinkerton CR, Atra A, Ashley S, Lewis I, Spooner D, Cannon S, Grimer R, Cotterill SJ, Craft AW. Local therapy and other factors influencing site of relapse in patients with localised Ewing's sarcoma. United Kingdom Children's Cancer Study Group (UKCCSG). Eur J Cancer 1999; 35:1698-704. [PMID: 10674016 DOI: 10.1016/s0959-8049(99)00144-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Relapse patterns have been documented in 191 children with localised Ewing's sarcoma treated with the United Kingdom Children's Cancer Group (UKCCSG) Ewing's Tumour regimen ET2. All received chemotherapy comprising ifosfamide, vincristine, doxorubicin and actinomycin D. Local treatment modality was excision and or radiotherapy depending on tumour site and response to primary chemotherapy. Although not strictly comparable, due to the clinical indications used for each modality, local relapse rates were very low and were similar, irrespective of the type of local treatment modality: radiotherapy (3/56), surgery (7/114) or a combination (0/20). Combined relapse (local + distant) rates were similarly low irrespective of the type of local therapy: radiotherapy (4/56), surgery (4/114) or a combination (0/20). Overall survival was lower in females (P = < 0.04), older children (P = < 0.002) and those with primaries at sites other than long bones (P = < 0.02). It is concluded that with effective intensive chemotherapy combined with either radiotherapy or surgery, local control in this study was excellent at sites other than the pelvis. Preventing distant relapse, predominantly to lung and bone, remains the major challenge.
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Murphy M, Godson C, Cannon S, Kato S, Mackenzie HS, Martin F, Brady HR. Suppression subtractive hybridization identifies high glucose levels as a stimulus for expression of connective tissue growth factor and other genes in human mesangial cells. J Biol Chem 1999; 274:5830-4. [PMID: 10026205 DOI: 10.1074/jbc.274.9.5830] [Citation(s) in RCA: 292] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Accumulation of mesangial matrix is a pivotal event in the pathophysiology of diabetic nephropathy. The molecular triggers for matrix production are still being defined. Here, suppression subtractive hybridization identified 15 genes differentially induced when primary human mesangial cells are exposed to high glucose (30 mM versus 5 mM) in vitro. These genes included (a) known regulators of mesangial cell activation in diabetic nephropathy (fibronectin, caldesmon, thrombospondin, and plasminogen activator inhibitor-1), (b) novel genes, and (c) known genes whose induction by high glucose has not been reported. Prominent among the latter were genes encoding cytoskeleton-associated proteins and connective tissue growth factor (CTGF), a modulator of fibroblast matrix production. In parallel experiments, elevated CTGF mRNA levels were demonstrated in glomeruli of rats with streptozotocin-induced diabetic nephropathy. Mannitol provoked less mesangial cell CTGF expression in vitro than high glucose, excluding hyperosmolality as the key stimulus. The addition of recombinant CTGF to cultured mesangial cells enhanced expression of extracellular matrix proteins. High glucose stimulated expression of transforming growth factor beta1 (TGF-beta1), and addition of TGF-beta1 to mesangial cells triggered CTGF expression. CTGF expression induced by high glucose was partially suppressed by anti-TGF-beta1 antibody and by the protein kinase C inhibitor GF 109203X. Together, these data suggest that 1) high glucose stimulates mesangial CTGF expression by TGFbeta1-dependent and protein kinase C dependent pathways, and 2) CTGF may be a mediator of TGFbeta1-driven matrix production within a diabetic milieu.
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Miller MJ, Rioux L, Prendergast GV, Cannon S, White MA, Meinkoth JL. Differential effects of protein kinase A on Ras effector pathways. Mol Cell Biol 1998; 18:3718-26. [PMID: 9632754 PMCID: PMC108954 DOI: 10.1128/mcb.18.7.3718] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1997] [Accepted: 03/26/1998] [Indexed: 02/07/2023] Open
Abstract
Ras mutants with the ability to interact with different effectors have played a critical role in the identification of Ras-dependent signaling pathways. We used two mutants, RasS35 and RasG37, which differ in their ability to bind Raf-1, to examine Ras-dependent signaling in thyroid epithelial cells. Wistar rat thyroid cells are dependent upon thyrotropin (TSH) for growth. Although TSH-stimulated mitogenesis requires Ras, TSH activates protein kinase A (PKA) and downregulates signaling through Raf and the mitogen-activated protein kinase (MAPK) cascade. Cells expressing RasS35, a mutant which binds Raf, or RasG37, a mutant which binds RalGDS, exhibited TSH-independent proliferation. RasS35 stimulated morphological transformation and anchorage-independent growth. RasG37 stimulated proliferation but not transformation as measured by these indices. TSH exerted markedly different effects on the Ras mutants and transiently repressed MAPK phosphorylation in RasS35-expressing cells. In contrast, TSH stimulated MAPK phosphorylation and growth in cells expressing RasG37. The Ras mutants, in turn, exerted differential effects on TSH signaling. RasS35 abolished TSH-stimulated changes in cell morphology and thyroglobulin expression, while RasG37 had no effect on these activities. Together, the data indicate that cross talk between Ras and PKA discriminates between distinct Ras effector pathways.
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Maxfield MC, Lewis RE, Cannon S. Training staff to prevent aggressive behavior of cognitively impaired elderly patients during bathing and grooming. J Gerontol Nurs 1996; 22:37-43. [PMID: 8698962 DOI: 10.3928/0098-9134-19960101-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
1. Cognitively impaired elderly patients often become aggressive toward caregivers who are providing assistance with bathing and grooming, but caregivers can learn methods to prevent or reduce some of the aggression. 2. The R.E.S.P.E.C.T. model describes key practices caregivers can use to better meet patient needs and reduce aggression, increasing their understanding and skill. 3. In addition to training, observation of performance and consultation are important steps in enabling caregivers to apply and maintain their skills.
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Morrison M, Bell JP, Brodsky MH, Cannon S, Elkins ER, Funk B, Gehring T, Indyk H, Katz SE, Layloff TP, Sabater JT, Thiex N. Membership Committee. J AOAC Int 1996. [DOI: 10.1093/jaoac/79.1.323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Green R, Saifuddin A, Cannon S, Renton P. Primary osteosarcoma of the spine. Clin Radiol 1994. [DOI: 10.1016/s0009-9260(05)82844-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Hale H, Saifuddin A, Cannon S. Imaging of periosteal osteosarcomas. Clin Radiol 1994. [DOI: 10.1016/s0009-9260(05)82846-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Callaway E, Truelson JM, Wolf GT, Thomas-Kincaid L, Cannon S. Predictive value of objective esophageal insufflation testing for acquisition of tracheoesophageal speech. Laryngoscope 1992; 102:704-8. [PMID: 1602920 DOI: 10.1288/00005537-199206000-00018] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This prospective study was undertaken to assess the predictive value of esophageal insufflation on the acquisition of tracheoesophageal (TE) speech. Fourteen total laryngectomy patients were evaluated prior to tracheoesophageal puncture (TEP) using objective esophageal pressure measurements. These patients then were followed prospectively for 6 to 13 months. Speech was assessed at the time of prosthesis fitting, at 1 month, at less than 6 months, and at greater than 6 months post-TEP. No patient underwent pharyngeal myotomy. Pre-TEP esophageal insufflation pressure was associated (P = .065) with successful TE speech at the time of prosthesis fitting, but was not associated with successful TE speech acquisition after 6 months. This study's results suggest that patients with poor pre-TEP esophageal insufflation test results will usually obtain successful TE speech given adequate time and training, even without pharyngeal myotomy.
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Stein RC, Cannon S, Cassoni A, Pringle JS, Stoker DJ, Souhami RL. Clinical oncology: case presentations from oncology centres. 1. Ewing's sarcoma. The London Bone Tumour Service. Eur J Cancer 1991; 27:1525-33. [PMID: 1835871 DOI: 10.1016/0277-5379(91)90042-c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The management of a case of Ewing's sarcoma of the left proximal humerus in a 15-year-old girl is presented, and the radiological and pathological findings are described. The chemotherapeutic, radiotherapeutic and surgical management of Ewing's sarcoma are discussed with reference to the case.
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Astrup A, Toubro S, Cannon S, Hein P, Madsen J. Thermogenic synergism between ephedrine and caffeine in healthy volunteers: a double-blind, placebo-controlled study. Metabolism 1991; 40:323-9. [PMID: 2000046 DOI: 10.1016/0026-0495(91)90117-f] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Animal and human studies have suggested a thermogenic synergism between ephedrine (E), a beta-agonist, and caffeine (C), an adenosine antagonist, which may be suitable for the treatment of obesity. To study this phenomenon, the thermogenic effect of single doses of oral placebo, E 10 mg, E 20 mg, C 100 mg, and C 200 mg were compared with the effects of three different combinations of E + C, 10 mg/200 mg, 20 mg/100 mg, and 20 mg/200 mg, measured by indirect calorimetry in six healthy, lean subjects. The thermogenic effect after E + C 20 mg/200 mg was larger than that of any of the other combinations. In this dose ratio, ephedrine and caffeine exerted a supra-additive synergism, whereas the thermogenic effects of the other two combinations were only additive. The 3-hour postintake increase in systolic blood pressure after all three combinations averaged 5 to 7 mm Hg more than placebo (P less than .01), which exceeded the predicted additive effect fivefold to sevenfold. Diastolic blood pressure was not increased by E + C 20 mg/200 mg, whereas the other two combinations increased it by approximately 4 mm Hg more than placebo. E + C 20 mg/100 mg and 20 mg/200 mg increased heart rate more than placebo, while E + C 10 mg/200 mg had no effect on heart rate. As expected, all combinations increased plasma glucose, insulin, and C-peptide from their ephedrine content. No significant effects of the combinations were found on plasma lactate, glycerol, nonesterified fatty acids (NEFA), triglyceride, potassium, or sodium.(ABSTRACT TRUNCATED AT 250 WORDS)
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Astrup A, Toubro S, Cannon S, Hein P, Breum L, Madsen J. Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers. Am J Clin Nutr 1990; 51:759-67. [PMID: 2333832 DOI: 10.1093/ajcn/51.5.759] [Citation(s) in RCA: 176] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In humans caffeine stimulates thermogenesis by unknown mechanisms and its effect on body weight has not been studies. The effect of placebo and 100, 200, and 400 mg oral caffeine on energy expenditure, plasma concentrations of substrates and hormones, blood pressure, and heart rate was investigated in a double-blind study in healthy subjects who had a moderate habitual caffeine consumption. Caffeine increased energy expenditure dose dependently and the thermogenic response was positively correlated with the response in plasma caffeine (r = 0.52; p less than 0.018), plasma lactate (r = 0.79; p less than 0.000001), and plasma triglyceride (r = 0.53; p less than 0.02). Stepwise regression analysis with the thermogenic response as the dependent variable excluded plasma caffeine and yielded the following equation: thermic effect (kcal/3 h) = -0.00459 X heart rate + 0.30315 X (triglyceride) + 0.53114 X (lactate) + 15.34 (r = 0.86; p = 0.0001). The results suggest that lactate and triglyceride production and increased vascular smooth muscle tone may be responsible for the major part of the thermogenic effect of caffeine.
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Roy H, Cannon S, Gilson M. Assembly of Rubisco from native subunits. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 957:323-34. [PMID: 3058207 DOI: 10.1016/0167-4838(88)90221-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Large subunits of ribulosebisphosphate carboxylase/oxygenase (Rubisco) (3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39) from prokaryotic sources can assemble into intact enzyme either in vitro or in Escherichia coli cells. Large subunits of higher plant Rubisco do not assemble into Rubisco in E. coli cells, nor is it possible to reconstitute higher plant Rubisco from its dissociated subunits in vitro. This behavior represents an obstacle to any practical attempts at engineering the higher plant enzyme, and it suggests that the in vivo assembly mechanism of higher plant Rubisco must be more complex than is commonly expected for oligomeric proteins of organelles. In pea chloroplasts, a binding protein interacts with newly synthesized large subunits, in quantities expected for an intermediate in the assembly process, as judged by Western blotting. Radiotracer-labeled large subunits which interact with this binding protein can be shown to assemble into Rubisco in reactions which lead to changes in the aggregation state of the binding protein. Antibody to this binding protein specifically inhibits the assembly of these subunits into Rubisco. Rubisco synthesis appears to be subject to many types of control: gene dosage, transcription rate, selective translation of message, post-translational degradation and threshold concentration effects have been observed in various organisms' synthesis of Rubisco. The biochemical mechanisms underlying most of these effects have not been elucidated. The post-translational assembly mechanism in particular appears to require further study.
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Roy H, Cannon S. Ribulose bisphosphate carboxylase assembly: what is the role of the large subunit binding protein? Trends Biochem Sci 1988; 13:163-5. [PMID: 3255196 DOI: 10.1016/0968-0004(88)90139-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Roy H, Hubbs A, Cannon S. Stability and Dissociation of the Large Subunit RuBisCO Binding Protein Complex in Vitro and in Organello. PLANT PHYSIOLOGY 1988; 86:50-3. [PMID: 16665892 PMCID: PMC1054426 DOI: 10.1104/pp.86.1.50] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We are studying the stability of the binding protein which associates with newly synthesized large subunits of ribulose bisphosphate carboxylase. In chloroplast extracts, it has been shown that a dodecameric complex of the large subunit binding protein dissociates extensively into binding protein monomers and 7S (117 kilodaltons) large subunit-containing complexes in the presence of ATP. The concentrations of ATP which bring this about are quite low, prompting some investigators to suggest that the dodecameric complex might not exist in vivo. We have found, however, that in concentrated chloroplast extracts, at protein concentrations which are closer to those which occur in organello, the dissociation of the binding protein complex by ATP is much less extensive. For this reason, we have tested the stability of the binding protein in organello, by illuminating chloroplasts followed by lysis and polyacrylamide gel electrophoresis of the extracts. Radioactive large subunits associated with the dodecameric binding protein dissociated extensively in the light. The results are consistent with the idea that the high molecular weight form of the binding protein can function as a reservoir of large subunits which can be tapped in vivo, in a reaction dependent on light and ATP.
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Roy H, Chaudhari P, Cannon S. Incorporation of Large Subunits into Ribulose Bisphosphate Carboxylase in Chloroplast Extracts : Influence of Added Small Subunits and of Conditions during Synthesis. PLANT PHYSIOLOGY 1988; 86:44-9. [PMID: 16665891 PMCID: PMC1054425 DOI: 10.1104/pp.86.1.44] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The incorporation of newly synthesized large subunits into ribulose bisphosphate carboxylase/oxygenase (RuBisCO) in pea chloroplast extracts occurs at the expense of intermediate forms of the large subunit which are complexed with a binding protein. Most subunits of this binding protein are found in dodecameric complexes in chloroplast extracts. Addition of small subunits to these extracts results in approximately 40 to 60% increased incorporation of newly made large subunits into RuBisCO at low or zero concentrations of ATP, but is without significant effect at high concentrations of ATP, a condition in which the dodecameric binding protein complex is dissociated into subunits. Overall, these data support the assumption that the incorporation of large subunits into RuBisCO in chloroplast extracts reflects de novo assembly rather than ;mere' exchange of subunits. The in vitro assembly of large subunits into RuBisCO is a function of the conditions under which the large subunits are synthesized in organello. When the large subunits are made in chloroplasts suspended in 188 millimolar sorbitol, they are approximately 2- to 3-fold better able to assemble into RuBisCO when subsequently incubated in vitro than when they are synthesized in chloroplasts suspended in 375 millimolar sorbitol. This observation indicates that mere synthesis of large subunits is not sufficient to confer maximal assembly competence on large subunits.
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