1
|
van Walsum J, Kok B, Blans MJ. Point-of-care ultrasound (POCUS) use in dyspnea, nontraumatic hypotension and shock; how much training is needed for competency? Eur J Intern Med 2023; 113:122-124. [PMID: 37087387 DOI: 10.1016/j.ejim.2023.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 04/17/2023] [Indexed: 04/24/2023]
Affiliation(s)
- J van Walsum
- Intensive Care Unit, Rijnstate, Wagnerlaan 55, Arnhem, AD 6815, The Netherlands.
| | - B Kok
- Department of Internal Medicine, Radboudumc, The Netherlands
| | - M J Blans
- Intensive Care Unit, Rijnstate, Arnhem, The Netherlands
| |
Collapse
|
2
|
Olgers TJ, Lieveld AWE, Kok B, Heijmans J, Salet D, Assman NL, Postma DF, Bauer MP, Nanayakkara PWB, Meijer K, Bosch FH, Kooistra H. Screening for asymptomatic deep vein thrombosis in COVID-19 patients admitted to the medical ward: a cross-sectional study. J Ultrasound 2022; 26:163-168. [PMID: 35567703 PMCID: PMC9107005 DOI: 10.1007/s40477-022-00689-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 04/19/2022] [Indexed: 01/08/2023] Open
Abstract
Purpose Patients with COVID-19 have an increased risk for venous thrombo-embolism (VTE), especially pulmonary embolism. The exact prevalence of asymptomatic DVT is not known, as is the usefulness of screening for DVT in patients admitted to ward with COVID-19. We have studied the prevalence of asymptomatic DVT. Methods We performed a cross-sectional observational multi-center study at four university medical centers in The Netherlands. All adult patients admitted with COVID-19 to a medical ward were eligible for inclusion, including patients who were transferred back from the ICU to the ward. The study protocol consisted of weekly cross-sectional rounds of compression ultrasound. Results In total, 125 patients were included in the study. A significant proportion of patients (N = 34 (27%)) had developed a VTE during their admission for COVID-19 before the study ultrasound was performed. In most VTE cases (N = 27 (79%)) this concerned pulmonary embolism. A new asymptomatic DVT was found in 5 of 125 patients (4.0%; 95% CI 1.3–9.1%) (Table 2). Nine patients (7.2%; 95% CI 3.3–13.2%) developed a VTE (all PE) diagnosed within 28 days after the screening US was performed. Conclusion We have shown a low prevalence (4%) of newly discovered asymptomatic DVT outside the ICU-setting in COVID-19 patients. Despite this low prevalence, nine patients developed PE (7%) within 28 days after ultrasound. This favors the hypothesis of local thrombus formation in the lungs. Based on our findings and literature, we do not recommend US-screening of asymptomatic patients with COVID-19 admitted to the ward.
Collapse
Affiliation(s)
- T J Olgers
- Department of Internal Medicine, Section Acute Internal Medicine, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 970 RD, Groningen, The Netherlands.
| | - A W E Lieveld
- General and Acute Internal Medicine Department of Internal Medicine, Amsterdam Public Health Research Institute, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - B Kok
- Section Acute Internal Medicine, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - J Heijmans
- General and Acute Internal Medicine Department of Internal Medicine, Amsterdam Public Health Research Institute, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - D Salet
- General and Acute Internal Medicine Department of Internal Medicine, Amsterdam Public Health Research Institute, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - N L Assman
- Section Acute Internal Medicine, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - D F Postma
- Department of Internal Medicine, Infectious Diseases Service, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M P Bauer
- Department of Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - P W B Nanayakkara
- General and Acute Internal Medicine Department of Internal Medicine, Amsterdam Public Health Research Institute, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - K Meijer
- Department of Haematology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - F H Bosch
- Section Acute Internal Medicine, Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - H Kooistra
- Department of Haematology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| |
Collapse
|
3
|
Blans MJ, Kok B, Gils-Poppe HJV, Hoeven JGVD, Bosch FH. Correspondence - Evaluation of a basic point-of-care ultrasound course for residents in internal medicine. Acute Med 2022; 21:157-160. [PMID: 36427217 DOI: 10.52964/amja.0918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Point-of-care ultrasound (POCUS) integrates imaging into the physical examination at the bedside. This offers the advantage of instant clinical information and has shown to speed up the diagnostic process, and to improve diagnostic accuracy and correct treatment.
Collapse
Affiliation(s)
- M J Blans
- MD, PhD, Department of Intensive Care, Rijnstate Hospital, The Netherlands
| | - B Kok
- MD, Department of Internal Medicine, Radboud University Medical Center, The Netherlands
| | - H J van Gils-Poppe
- MSc. Department of Educational services, Rijnstate Hospital, The Netherlands
| | - J G van der Hoeven
- MD, PhD, Department of Intensive Care, Radboud University Medical Center, The Netherlands
| | - F H Bosch
- MD, PhD, Department of Internal Medicine, Rijnstate Hospital, The Netherlands
| |
Collapse
|
4
|
Kessler EL, Wang JW, Kok B, Brans MA, Nederlof A, van Stuijvenberg L, Huang C, Vink A, Arslan F, Efimov IR, Lam CSP, Vos MA, de Kleijn DPV, Fontes MSC, van Veen TAB. Ventricular TLR4 Levels Abrogate TLR2-Mediated Adverse Cardiac Remodeling upon Pressure Overload in Mice. Int J Mol Sci 2021; 22:ijms222111823. [PMID: 34769252 PMCID: PMC8583975 DOI: 10.3390/ijms222111823] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 12/15/2022] Open
Abstract
Involvement of the Toll-like receptor 4 (TLR4) in maladaptive cardiac remodeling and heart failure (HF) upon pressure overload has been studied extensively, but less is known about the role of TLR2. Interplay and redundancy of TLR4 with TLR2 have been reported in other organs but were not investigated during cardiac dysfunction. We explored whether TLR2 deficiency leads to less adverse cardiac remodeling upon chronic pressure overload and whether TLR2 and TLR4 additively contribute to this. We subjected 35 male C57BL/6J mice (wildtype (WT) or TLR2 knockout (KO)) to sham or transverse aortic constriction (TAC) surgery. After 12 weeks, echocardiography and electrocardiography were performed, and hearts were extracted for molecular and histological analysis. TLR2 deficiency (n = 14) was confirmed in all KO mice by PCR and resulted in less hypertrophy (heart weight to tibia length ratio (HW/TL), smaller cross-sectional cardiomyocyte area and decreased brain natriuretic peptide (BNP) mRNA expression, p < 0.05), increased contractility (QRS and QTc, p < 0.05), and less inflammation (e.g., interleukins 6 and 1β, p < 0.05) after TAC compared to WT animals (n = 11). Even though TLR2 KO TAC animals presented with lower levels of ventricular TLR4 mRNA than WT TAC animals (13.2 ± 0.8 vs. 16.6 ± 0.7 mg/mm, p < 0.01), TLR4 mRNA expression was increased in animals with the largest ventricular mass, highest hypertrophy, and lowest ejection fraction, leading to two distinct groups of TLR2 KO TAC animals with variations in cardiac remodeling. This variation, however, was not seen in WT TAC animals even though heart weight/tibia length correlated with expression of TLR4 in these animals (r = 0.078, p = 0.005). Our data suggest that TLR2 deficiency ameliorates adverse cardiac remodeling and that ventricular TLR2 and TLR4 additively contribute to adverse cardiac remodeling during chronic pressure overload. Therefore, both TLRs may be therapeutic targets to prevent or interfere in the underlying molecular processes.
Collapse
Affiliation(s)
- Elise L. Kessler
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
- Laboratory Experimental Cardiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3508GA Utrecht, The Netherlands;
- Correspondence: ; Tel.: +31-628706156
| | - Jiong-Wei Wang
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore; (J.-W.W.); (C.H.)
- Cardiovascular Research Institute, National University Heart Centre Singapore, Singapore 117599, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
- Nanomedicine Translational Research Programme, Centre for NanoMedicine, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - Bart Kok
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| | - Maike A. Brans
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
- Laboratory Experimental Cardiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3508GA Utrecht, The Netherlands;
| | - Angelique Nederlof
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| | - Leonie van Stuijvenberg
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| | - Chenyuan Huang
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore; (J.-W.W.); (C.H.)
- Cardiovascular Research Institute, National University Heart Centre Singapore, Singapore 117599, Singapore
- Nanomedicine Translational Research Programme, Centre for NanoMedicine, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 117597, Singapore
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, 3508GA Utrecht, The Netherlands;
| | - Fatih Arslan
- Laboratory Experimental Cardiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3508GA Utrecht, The Netherlands;
- Department of Cardiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3508GA Utrecht, The Netherlands
| | - Igor R. Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC 20052, USA;
| | - Carolyn S. P. Lam
- National Heart Centre Singapore and Duke-National University of Singapore, 5 Hospital Dr, Singapore 169609, Singapore;
- UMC Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands
| | - Marc A. Vos
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| | - Dominique P. V. de Kleijn
- Department of Vascular Surgery, The Netherlands & Netherlands Heart Institute, University Medical Center Utrecht, Utrecht University, 3508GA Utrecht, The Netherlands;
- The Netherlands Heart Institute, Moreelsepark 1, 3511EP Utrecht, The Netherlands
| | - Magda S. C. Fontes
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| | - Toon A. B. van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht University, 3584CM Utrecht, The Netherlands; (B.K.); (M.A.B.); (A.N.); (L.v.S.); (M.A.V.); (M.S.C.F.); (T.A.B.v.V.)
| |
Collapse
|
5
|
Le Large TYS, Bijlsma MF, El Hassouni B, Mantini G, Lagerweij T, Henneman AA, Funel N, Kok B, Pham TV, de Haas R, Morelli L, Knol JC, Piersma SR, Kazemier G, van Laarhoven HWM, Giovannetti E, Jimenez CR. Focal adhesion kinase inhibition synergizes with nab-paclitaxel to target pancreatic ductal adenocarcinoma. J Exp Clin Cancer Res 2021; 40:91. [PMID: 33750427 PMCID: PMC7941981 DOI: 10.1186/s13046-021-01892-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/24/2021] [Indexed: 02/08/2023] Open
Abstract
Background Pancreatic ductal adenocarcinoma (PDAC) is a very lethal disease, with minimal therapeutic options. Aberrant tyrosine kinase activity influences tumor growth and is regulated by phosphorylation. We investigated phosphorylated kinases as target in PDAC. Methods Mass spectrometry-based phosphotyrosine proteomic analysis on PDAC cell lines was used to evaluate active kinases. Pathway analysis and inferred kinase activity analysis was performed to identify novel targets. Subsequently, we investigated targeting of focal adhesion kinase (FAK) in vitro with drug perturbations in combination with chemotherapeutics used against PDAC. Tyrosine phosphoproteomics upon treatment was performed to evaluate signaling. An orthotopic model of PDAC was used to evaluate the combination of defactinib with nab-paclitaxel. Results PDAC cell lines portrayed high activity of multiple receptor tyrosine kinases to various degree. The non-receptor kinase, FAK, was identified in all cell lines by our phosphotyrosine proteomic screen and pathway analysis. Targeting of this kinase with defactinib validated reduced phosphorylation profiles. Additionally, FAK inhibition had anti-proliferative and anti-migratory effects. Combination with (nab-)paclitaxel had a synergistic effect on cell proliferation in vitro and reduced tumor growth in vivo. Conclusions Our study shows high phosphorylation of several oncogenic receptor tyrosine kinases in PDAC cells and validated FAK inhibition as potential synergistic target with Nab-paclitaxel against this devastating disease. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-021-01892-z.
Collapse
Affiliation(s)
- T Y S Le Large
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University Amsterdam, Amsterdam, The Netherlands.,Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.,Laboratory for Experimental Oncology and Radiobiology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - M F Bijlsma
- Laboratory for Experimental Oncology and Radiobiology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Oncode Institute, Amsterdam, The Netherlands
| | - B El Hassouni
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - G Mantini
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.,OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.,Cancer Pharmacology Lab, AIRC-Start-Up, Fondazione Pisana per la Scienza, Pisa, Italy
| | - T Lagerweij
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.,Department of Neurosurgery, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University Amsterdam, Amsterdam, The Netherlands
| | - A A Henneman
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - N Funel
- Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - B Kok
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - T V Pham
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - R de Haas
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - L Morelli
- Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - J C Knol
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - S R Piersma
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands
| | - G Kazemier
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University Amsterdam, Amsterdam, The Netherlands
| | - H W M van Laarhoven
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.,Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - E Giovannetti
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands. .,Cancer Pharmacology Lab, AIRC-Start-Up, Fondazione Pisana per la Scienza, Pisa, Italy.
| | - C R Jimenez
- OncoProteomics Laboratory, Department of Medical Oncology, Cancer, Cancer Center Amsterdam, Amsterdam University Medical Centers, VU University, De Boelelaan 1117, 1081, HV, Amsterdam, The Netherlands.
| |
Collapse
|
6
|
Badrising SK, Keijmel SP, Kok B. [Awake prone positioning in covid-19 patients]. Ned Tijdschr Geneeskd 2021; 165:D5634. [PMID: 33651518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Awake prone positioning in COVID-19 patients with respiratory failure has been applied worldwide. We hypothesize that early intervention of awake prone positioning in this patient category might avoid invasive mechanical ventilation and referral to ICU. We observed approximately 30 patients in Suriname in whom awake prone positioning was applied. Also, we reviewed the existing literature on awake prone positioning and discussion of the advantages and disadvantages of this relatively simple intervention. Prospective studies show an improvement in oxygenation, albeit sometimes temporary, but not a reduction in mortality rate or intubation. Mean duration of symptoms in these studies is 10-11 days. Awake prone positioning in COVID-19 patients with a longer duration of symptoms does not improve survival or need for intubation. No prospective studies on early prone position in COVID-19 patients have been conducted yet.
Collapse
Affiliation(s)
| | - S P Keijmel
- Radboudumc, afd. Interne Geneeskunde, Nijmegen
| | - B Kok
- Radboudumc, afd. Interne Geneeskunde, Nijmegen
- Contact: B. Kok
| |
Collapse
|
7
|
Le Large TY, Mantini G, Meijer LL, Pham TV, Funel N, van Grieken NC, Kok B, Knol J, van Laarhoven HW, Piersma SR, Jimenez CR, Kazemier G, Giovannetti E, Bijlsma MF. Microdissected pancreatic cancer proteomes reveal tumor heterogeneity and therapeutic targets. JCI Insight 2020; 5:138290. [PMID: 32634123 PMCID: PMC7455080 DOI: 10.1172/jci.insight.138290] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/24/2020] [Indexed: 12/12/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is characterized by a relative paucity of cancer cells that are surrounded by an abundance of nontumor cells and extracellular matrix, known as stroma. The interaction between stroma and cancer cells contributes to poor outcome, but how proteins from these individual compartments drive aggressive tumor behavior is not known. Here, we report the proteomic analysis of laser-capture microdissected (LCM) PDAC samples. We isolated stroma, tumor, and bulk samples from a cohort with long- and short-term survivors. Compartment-specific proteins were measured by mass spectrometry, yielding what we believe to be the largest PDAC proteome landscape to date. These analyses revealed that, in bulk analysis, tumor-derived proteins were typically masked and that LCM was required to reveal biology and prognostic markers. We validated tumor CALB2 and stromal COL11A1 expression as compartment-specific prognostic markers. We identified and functionally addressed the contributions of the tumor cell receptor EPHA2 to tumor cell viability and motility, underscoring the value of compartment-specific protein analysis in PDAC.
Collapse
Affiliation(s)
- Tessa Y.S. Le Large
- Department of Surgery and
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- Laboratory for Experimental Oncology and Radiobiology, Amsterdam University Medical Centers, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Giulia Mantini
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- Cancer Pharmacology Lab, Fondazione Pisana per la Scienza, Pisa, Italy
| | - Laura L. Meijer
- Department of Surgery and
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Thang V. Pham
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Niccola Funel
- Unit of Anatomic Pathology II, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy
| | | | | | - Jaco Knol
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Hanneke W.M. van Laarhoven
- Department of Medical Oncology, Amsterdam University Medical Centers, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Sander R. Piersma
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Connie R. Jimenez
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- OncoProteomics Laboratory, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | | | - Elisa Giovannetti
- Department of Medical Oncology, Amsterdam University Medical Centers, Free University Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- Cancer Pharmacology Lab, Fondazione Pisana per la Scienza, Pisa, Italy
| | - Maarten F. Bijlsma
- Laboratory for Experimental Oncology and Radiobiology, Amsterdam University Medical Centers, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
- Oncode Institute, Amsterdam, Netherlands
| |
Collapse
|
8
|
van den Heuvel FMA, Vos JL, Koop Y, van Dijk APJ, Duijnhouwer AL, de Mast Q, van de Veerdonk FL, Bosch F, Kok B, Netea MG, Hoogerwerf J, Hoefsloot W, Tjwa ETTL, de Korte CL, van Kimmenade RRJ, Nijveldt R. Cardiac function in relation to myocardial injury in hospitalised patients with COVID-19. Neth Heart J 2020; 28:410-417. [PMID: 32643071 PMCID: PMC7341471 DOI: 10.1007/s12471-020-01458-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Previous studies have reported on myocardial injury in patients with coronavirus infectious disease 19 (COVID-19) defined as elevated cardiac biomarkers. Whether elevated biomarkers truly represent myocardial dysfunction is not known. The aim of this study was to explore the incidence of ventricular dysfunction and assess its relationship with biomarker analyses. METHODS This cross-sectional study ran from April 1 to May 12, 2020, and consisted of all consecutively admitted patients to the Radboud university medical centre nursing ward for COVID-19. Laboratory assessment included high-sensitivity Troponin T and N‑terminal pro-B-type natriuretic peptide (NT-proBNP). Echocardiographic evaluation focused on left and right ventricular systolic function and global longitudinal strain (GLS). RESULTS In total, 51 patients were included, with a median age of 63 years (range 51-68 years) of whom 80% was male. Troponin T was elevated (>14 ng/l) in 47%, and a clinically relevant Troponin T elevation (10 × URL) was found in three patients (6%). NT-proBNP was elevated (>300 pg/ml) in 24 patients (47%), and in four (8%) the NT-proBNP concentration was >1,000 pg/ml. Left ventricular dysfunction (ejection fraction <52% and/or GLS >-18%) was observed in 27%, while right ventricular dysfunction (TAPSE <17 mm and/or RV S' < 10 cm/s) was seen in 10%. There was no association between elevated Troponin T or NT-proBNP and left or right ventricular dysfunction. Patients with confirmed pulmonary embolism had normal right ventricular function. CONCLUSIONS In hospitalised patients, it seems that COVID-19 predominantly affects the respiratory system, while cardiac dysfunction occurs less often. Based on a single echocardiographic evaluation, we found no relation between elevated Troponin T or NT-proBNP, and ventricular dysfunction. Echocardiography has limited value in screening for ventricular dysfunction.
Collapse
Affiliation(s)
- F M A van den Heuvel
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - J L Vos
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Y Koop
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - A P J van Dijk
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - A L Duijnhouwer
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Q de Mast
- Department of Internal Medicine and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - F L van de Veerdonk
- Department of Internal Medicine and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - F Bosch
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - B Kok
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - M G Netea
- Department of Internal Medicine and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, The Netherlands
| | - J Hoogerwerf
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - W Hoefsloot
- Department of Pulmonology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - E T T L Tjwa
- Department of Gastroenterology and Hepatology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - C L de Korte
- Department of Radiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - R R J van Kimmenade
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - R Nijveldt
- Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands.
| |
Collapse
|
9
|
Le Large TY, Meijer LL, Paleckyte R, Boyd LN, Kok B, Wurdinger T, Schelfhorst T, Piersma SR, Pham TV, van Grieken NC, Zonderhuis BM, Daams F, van Laarhoven HW, Bijlsma MF, Jimenez CR, Giovannetti E, Kazemier G. Combined Expression of Plasma Thrombospondin-2 and CA19-9 for Diagnosis of Pancreatic Cancer and Distal Cholangiocarcinoma: A Proteome Approach. Oncologist 2020; 25:e634-e643. [PMID: 31943574 PMCID: PMC7160420 DOI: 10.1634/theoncologist.2019-0680] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 11/22/2019] [Indexed: 12/16/2022] Open
Abstract
Background Minimally invasive diagnostic biomarkers for patients with pancreatic ductal adenocarcinoma (PDAC) and distal cholangiocarcinoma (dCCA) are warranted to facilitate accurate diagnosis. This study identified diagnostic plasma proteins based on proteomics of tumor secretome. Materials and Methods Secretome of tumor and normal tissue was collected after resection of PDAC and dCCA. Differentially expressed proteins were measured by mass spectrometry. Selected candidate biomarkers and carbohydrate antigen 19‐9 (CA19‐9) were validated by enzyme‐linked immunosorbent assay in plasma from patients with PDAC (n = 82), dCCA (n = 29), benign disease (BD; n = 30), and healthy donors (HDs; n = 50). Areas under the curve (AUCs) of receiver operator characteristic curves were calculated to determine the discriminative power. Results In tumor secretome, 696 discriminatory proteins were identified, including 21 candidate biomarkers. Thrombospondin‐2 (THBS2) emerged as promising biomarker. Abundance of THBS2 in plasma from patients with cancer was significantly higher compared to HDs (p < .001, AUC = 0.844). Combined expression of THBS2 and CA19‐9 yielded the optimal discriminatory capacity (AUC = 0.952), similarly for early‐ and late‐stage disease (AUC = 0.971 and AUC = 0.911). Remarkably, this combination demonstrated a power similar to CA19‐9 to discriminate cancer from BD (AUC = 0.764), and THBS2 provided an additive value in patients with high expression levels of bilirubin. Conclusion Our proteome approach identified a promising set of candidate biomarkers. The combined plasma expression of THBS2/CA19‐9 is able to accurately distinguish patients with PDAC or dCCA from HD and BD. Implications for Practice The combined plasma expression of thrombospondin‐2 and carbohydrate antigen 19‐9 is able to accurately diagnose patients with pancreatic cancer and distal cholangiocarcinoma. This will facilitate minimally invasive diagnosis for these patients by distinguishing them from healthy individuals and benign diseases. This article identifies diagnostic plasma proteins to distinguish patients with pancreatic ductal adenocarcinoma and distal cholangiocarcinoma from benign disease and health donors and evaluates these new markers for additive value with CA19‐9 at different disease stages.
Collapse
Affiliation(s)
- Tessa Y.S. Le Large
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of AmsterdamAmsterdamThe Netherlands
| | - Laura L. Meijer
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Rosita Paleckyte
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Lenka N.C. Boyd
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Bart Kok
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Thomas Wurdinger
- Department of Neurosurgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Tim Schelfhorst
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Sander R. Piersma
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Thang V. Pham
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Nicole C.T. van Grieken
- Department of Pathology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Barbara M. Zonderhuis
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Freek Daams
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Hanneke W.M. van Laarhoven
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of AmsterdamAmsterdamThe Netherlands
| | - Maarten F. Bijlsma
- Laboratory of Experimental Oncology and Radiobiology, Cancer Center Amsterdam, Amsterdam University Medical Center, University of AmsterdamAmsterdamThe Netherlands
| | - Connie R. Jimenez
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| | - Elisa Giovannetti
- Department of Medical Oncology, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
- Cancer Pharmacology Lab, Associazione Italiana per la Ricerca sul Cancro (AIRC) Start‐Up Unit, Fondazione Pisana per la Scienza, University of PisaPisaItaly
| | - Geert Kazemier
- Department of Surgery, Cancer Center Amsterdam, Amsterdam University Medical Center, VU UniversityAmsterdamThe Netherlands
| |
Collapse
|
10
|
Qile M, Ji Y, Houtman MJC, Veldhuis M, Romunde F, Kok B, van der Heyden MAG. Identification of a PEST Sequence in Vertebrate K IR2.1 That Modifies Rectification. Front Physiol 2019; 10:863. [PMID: 31333502 PMCID: PMC6624654 DOI: 10.3389/fphys.2019.00863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/20/2019] [Indexed: 11/13/2022] Open
Abstract
KIR2.1 potassium channels, producing inward rectifier potassium current (IK1), are important for final action potential repolarization and a stable resting membrane potential in excitable cells like cardiomyocytes. Abnormal KIR2.1 function, either decreased or increased, associates with diseases such as Andersen-Tawil syndrome, long and short QT syndromes. KIR2.1 ion channel protein trafficking and subcellular anchoring depends on intrinsic specific short amino acid sequences. We hypothesized that combining an evolutionary based sequence comparison and bioinformatics will identify new functional domains within the C-terminus of the KIR2.1 protein, which function could be determined by mutation analysis. We determined PEST domain signatures, rich in proline (P), glutamic acid (E), serine (S), and threonine (T), within KIR2.1 sequences using the “epestfind” webtool. WT and ΔPEST KIR2.1 channels were expressed in HEK293T and COS-7 cells. Patch-clamp electrophysiology measurements were performed in the inside-out mode on excised membrane patches and the whole cell mode using AxonPatch 200B amplifiers. KIR2.1 protein expression levels were determined by western blot analysis. Immunofluorescence microscopy was used to determine KIR2.1 subcellular localization. An evolutionary conserved PEST domain was identified in the C-terminus of the KIR2.1 channel protein displaying positive PEST scores in vertebrates ranging from fish to human. No similar PEST domain was detected in KIR2.2, KIR2.3, and KIR2.6 proteins. Deletion of the PEST domain in California kingsnake and human KIR2.1 proteins (ΔPEST), did not affect plasma membrane localization. Co-expression of WT and ΔPEST KIR2.1 proteins resulted in heterotetrameric channel formation. Deletion of the PEST domain did not increase protein stability in cycloheximide assays [T½ from 2.64 h (WT) to 1.67 h (ΔPEST), n.s.]. WT and ΔPEST channels, either from human or snake, produced typical IK1, however, human ΔPEST channels displayed stronger intrinsic rectification. The current observations suggest that the PEST sequence of KIR2.1 is not associated with rapid protein degradation, and has a role in the rectification behavior of IK1 channels.
Collapse
Affiliation(s)
- Muge Qile
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Yuan Ji
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marien J C Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marlieke Veldhuis
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Fee Romunde
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Bart Kok
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
11
|
Le Large TYS, El Hassouni B, Funel N, Kok B, Piersma SR, Pham TV, Olive KP, Kazemier G, van Laarhoven HWM, Jimenez CR, Bijlsma MF, Giovannetti E. Proteomic analysis of gemcitabine-resistant pancreatic cancer cells reveals that microtubule-associated protein 2 upregulation associates with taxane treatment. Ther Adv Med Oncol 2019; 11:1758835919841233. [PMID: 31205498 PMCID: PMC6535709 DOI: 10.1177/1758835919841233] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/23/2019] [Indexed: 12/18/2022] Open
Abstract
Background: Chemoresistance hampers the treatment of patients suffering from pancreatic ductal adenocarcinoma (PDAC). Here we aimed to evaluate the (phospho)proteome of gemcitabine-sensitive and gemcitabine-resistant PDAC cells to identify novel therapeutic targets and predictive biomarkers. Methods: The oncogenic capabilities of gemcitabine-sensitive and resistant PDAC cells were evaluated in vitro and in vivo. Cultured cells were analyzed by label-free proteomics. Differential proteins and phosphopeptides were evaluated by gene ontology and for their predictive or prognostic biomarker potential with immunohistochemistry of tissue microarrays. Results: Gemcitabine-resistant cells had increased potential to induce xenograft tumours (p value < 0.001). Differential analyses showed that proteins associated with gemcitabine resistance are correlated with microtubule regulation. Indeed, gemcitabine-resistant cells displayed an increased sensitivity for paclitaxel in vitro (p < 0.001) and nab-paclitaxel had a strong anti-tumour efficacy in vivo. Microtubule-associated protein 2 (MAP2) was found to be highly upregulated (p = 0.002, fold change = 10) and phosphorylated in these resistant cells. Expression of MAP2 was correlated with a poorer overall survival in patients treated with gemcitabine in the palliative (p = 0.037) and adjuvant setting (p = 0.014). Conclusions: These data show an explanation as to why the combination of gemcitabine with nab-paclitaxel is effective in PDAC patients. The identified gemcitabine-resistance marker, MAP2, emerged as a novel prognostic marker in PDAC patients treated with gemcitabine and warrants further clinical investigation.
Collapse
Affiliation(s)
- Tessa Ya Sung Le Large
- Surgery, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, NetherlandsLEXOR, Center for Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, NetherlandsCancer Pharmacology Lab, AIRC-Start-Up, University Hospital of Pisa, Pisa, Italy
| | - Btissame El Hassouni
- Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Niccola Funel
- Cancer Pharmacology Lab, AIRC-Start-Up, University Hospital of Pisa, Pisa, Italy
| | - Bart Kok
- Surgery, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Sander R Piersma
- Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Thang V Pham
- Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Kenneth P Olive
- Departments of Medicine and Pathology and Cell Biology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York City, NY, USA
| | - Geert Kazemier
- Surgery, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Hanneke W M van Laarhoven
- Medical Oncology, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Connie R Jimenez
- Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Maarten F Bijlsma
- LEXOR, Center for Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, Netherlands
| | - Elisa Giovannetti
- Medical Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, Amsterdam, Netherlands
| |
Collapse
|
12
|
Evans B, Kok B, Wiebe E, Mather C, Zepeda-Gomez S. A64 TOTAL AGENESIS OF THE DORSAL PANCREAS (ADP) ASSOCIATED WITH PANCREATIC ADENOCARCINOMA: A CASE REPORT. J Can Assoc Gastroenterol 2019. [DOI: 10.1093/jcag/gwz006.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- B Evans
- General Surgery, Memorial University of Newfoundland, St. John’s, Canada
| | - B Kok
- University of Alberta Hospital, Edmonton, AB, Canada
| | - E Wiebe
- University of Alberta Hospital, Edmonton, AB, Canada
| | - C Mather
- University of Alberta Hospital, Edmonton, AB, Canada
| | - S Zepeda-Gomez
- Gastroenterology, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
13
|
Kok B, Sandha GS. A185 EUS-GUIDED LUMEN-APPOSING METAL STENT PLACEMENT SHOULD BE THE PREFERRED ENDOSCOPIC TREATMENT FOR ACUTE CHOLECYSTITIS IN A NON-SURGICAL PATIENT. J Can Assoc Gastroenterol 2019. [DOI: 10.1093/jcag/gwz006.184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- B Kok
- Endoscopy, University of Alberta Hospital, Edmonton, AB, Canada
| | - G S Sandha
- Medicine, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
14
|
Kok B, Zepeda-Gomez S. A266 OUTCOMES OF ENDOSCOPIC TREATMENT OF ZENKER’S DIVERTICULUM: EXPERIENCE IN A CANADIAN CENTRE. J Can Assoc Gastroenterol 2019. [DOI: 10.1093/jcag/gwz006.265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- B Kok
- Gastroenterology, University of Alberta, Edmonton, AB, Canada
| | - S Zepeda-Gomez
- Gastroenterology, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
15
|
Stams TRG, Dunnink A, van Everdingen WM, Beekman HDM, van der Nagel R, Kok B, Bierhuizen MFA, Cramer MJ, Meine M, Vos MA. Deleterious acute and chronic effects of bradycardic right ventricular apex pacing: consequences for arrhythmic outcome. Basic Res Cardiol 2017. [DOI: 10.1007/s00395-017-0636-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
16
|
Qile M, Ji Y, Houtman MJC, Romunde F, Veldhuis M, Kok B, Vos MA, Van Der Heyden MAG. P1077Identification of a PEST domain in the inward rectifier channel KIR2.1 involved in protein stability. Europace 2017. [DOI: 10.1093/ehjci/eux150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
17
|
Takanari H, Bourgonje VJA, Fontes MSC, Raaijmakers AJA, Driessen H, Jansen JA, van der Nagel R, Kok B, van Stuijvenberg L, Boulaksil M, Takemoto Y, Yamazaki M, Tsuji Y, Honjo H, Kamiya K, Kodama I, Anderson ME, van der Heyden MAG, van Rijen HVM, van Veen TAB, Vos MA. Calmodulin/CaMKII inhibition improves intercellular communication and impulse propagation in the heart and is antiarrhythmic under conditions when fibrosis is absent. Cardiovasc Res 2016; 111:410-21. [PMID: 27357638 PMCID: PMC4996261 DOI: 10.1093/cvr/cvw173] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 06/09/2016] [Accepted: 06/21/2016] [Indexed: 11/14/2022] Open
Abstract
AIM In healthy hearts, ventricular gap junctions are mainly composed by connexin43 (Cx43) and localize in the intercalated disc, enabling appropriate electrical coupling. In diseased hearts, Cx43 is heterogeneously down-regulated, whereas activity of calmodulin/calcium-calmodulin protein kinase II (CaM/CaMKII) signalling increases. It is unclear if CaM/CaMKII affects Cx43 expression/localization or impulse propagation. We analysed different models to assess this. METHODS AND RESULTS AC3-I mice with CaMKII genetically inhibited were subjected to pressure overload (16 weeks, TAC vs. sham). Optical and epicardial mapping was performed on Langendorff-perfused rabbit and AC3-I hearts, respectively. Cx43 subcellular distribution from rabbit/mouse ventricles was evaluated by immunoblot after Triton X-100-based fractionation. In mice with constitutively reduced CaMKII activity (AC3-I), conduction velocity (CV) was augmented (n = 11, P < 0.01 vs. WT); in AC3-I, CV was preserved after TAC, in contrast to a reduction seen in TAC-WT mice (-20%). Cx43 expression was preserved after TAC in AC3-I mice, though arrhythmias and fibrosis were still present. In rabbits, W7 (CaM inhibitor, 10 µM) increased CV (6-13%, n= 6, P< 0.05), while susceptibility to arrhythmias decreased. Immunoconfocal microscopy revealed enlarged Cx43 cluster sizes at intercalated discs of those hearts. Total Cx43 did not change by W7 (n= 4), whereas Triton X-100 insoluble Cx43 increased (+21%, n= 4, P< 0.01). Similar findings were obtained in AC3-I mouse hearts when compared with control, and in cultured dog cardiomyocytes. Functional implication was shown through increased intercellular coupling in cultured neonatal rat cardiomyocytes. CONCLUSION Both acute and chronic CaM/CaMKII inhibition improves conduction characteristics and enhances localization of Cx43 in the intercalated disc. In the absence of fibrosis, this reduced the susceptibility for arrhythmias.
Collapse
Affiliation(s)
- Hiroki Takanari
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan Department of Pathophysiology, Oita University School of Medicine, Yufu, Japan
| | - Vincent J A Bourgonje
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Magda S C Fontes
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Antonia J A Raaijmakers
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Helen Driessen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - John A Jansen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Roel van der Nagel
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Bart Kok
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Leonie van Stuijvenberg
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mohamed Boulaksil
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yoshio Takemoto
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Masatoshi Yamazaki
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Yukiomi Tsuji
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Haruo Honjo
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Kaichiro Kamiya
- Department of Cardiovascular Research, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | | | - Mark E Anderson
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MA, USA
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Harold V M van Rijen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Toon A B van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| |
Collapse
|
18
|
Boulaksil M, Bierhuizen M, Engelen M, Stein M, Kok B, Van Amersfoorth S, Vos M, Van Rijen H, De Bakker J, Van Veen T. 96-01: Spatial Heterogeneity of Cx43 and Its Non-phosphorylated Form Is an Arrhythmogenic Substrate of Polymorphic Ventricular Tachycardias in Compensated Cardiac Hypertrophy in Rats. Europace 2016. [DOI: 10.1093/europace/18.suppl_1.i59c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
19
|
Kok B, van de Ven MJT, van Leeuwen HJ. [Acute respiratory failure caused by minocycline]. Ned Tijdschr Geneeskd 2016; 160:D635. [PMID: 27879182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
BACKGROUND In the case of pneumonia an infectious cause is always considered first. However, toxic agents and medicines can also be the cause of pneumonia. CASE DESCRIPTION A 54-year-old woman was referred to the emergency department because of progressive dyspnoea, a non-productive cough, headache, and fever. She was admitted with the diagnosis community acquired pneumonia. Despite treatment with antibiotics and oxygen she developed hypoxic respiratory failure, which necessitated invasive mechanical ventilation. Imaging diagnostics showed extensive bilateral pulmonary consolidation, despite the absence of a causative agent in cultures. Further medical history-taking revealed that the patient had recently commenced a course of minocycline. She had used this medicine previously and had twice before developed pneumonia without the presence of a proven causative agent. Our differential diagnosis included the toxic effect of minocycline and we treated the patient with methylprednisolone. This resulted in rapid clinical improvement and full recovery of our patient. CONCLUSION Acute respiratory failure as a side effect of medication is rare, but nonetheless potentially life-threatening. Despite repeated exposure to minocycline, the link with pneumonia was not previously made in this patient.
Collapse
Affiliation(s)
- B Kok
- Rijnstate Ziekenhuis, Arnhem
| | | | | |
Collapse
|
20
|
Burgers PP, van der Heyden MAG, Kok B, Heck AJR, Scholten A. A Systematic Evaluation of Protein Kinase A–A-Kinase Anchoring Protein Interaction Motifs. Biochemistry 2014; 54:11-21. [DOI: 10.1021/bi500721a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Pepijn P. Burgers
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Marcel A. G. van der Heyden
- Department
of Medical Physiology, Division of Heart and Lungs, University Medical Centre Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Bart Kok
- Department
of Medical Physiology, Division of Heart and Lungs, University Medical Centre Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| | - Arjen Scholten
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular
Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- Netherlands Proteomics Centre, Padualaan
8, 3584 CH Utrecht, The Netherlands
| |
Collapse
|
21
|
Abstract
Experiments are described in which we used a mass spectrometer to monitor O(2) uptake of enclosed soil samples as a function of temperature. We found that an Arrhenius plot of the rate of O(2) uptake showed pronounced local maxima attributable to biological activity, whereas similar plots of rates obtained with abiotic soils yielded straight lines. This procedure thus provides a basis for distinguishing biological from chemical activity for reactions, such as O(2) uptake, that can occur via either biological or chemical pathways.
Collapse
Affiliation(s)
- R J Radmer
- Martin Marietta Laboratories, Baltimore, Maryland 21227
| | | |
Collapse
|
22
|
de Boer TP, Nalos L, Stary A, Kok B, Houtman MJC, Antoons G, van Veen TAB, Beekman JDM, de Groot BL, Opthof T, Rook MB, Vos MA, van der Heyden MAG. The anti-protozoal drug pentamidine blocks KIR2.x-mediated inward rectifier current by entering the cytoplasmic pore region of the channel. Br J Pharmacol 2010; 159:1532-41. [PMID: 20180941 DOI: 10.1111/j.1476-5381.2010.00658.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Pentamidine is a drug used in treatment of protozoal infections. Pentamidine treatment may cause sudden cardiac death by provoking cardiac arrhythmias associated with QTc prolongation and U-wave alterations. This proarrhythmic effect was linked to inhibition of hERG trafficking, but not to acute block of ion channels contributing to the action potential. Because the U-wave has been linked to the cardiac inward rectifier current (I(K1)), we examined the action and mechanism of pentamidine-mediated I(K1) block. EXPERIMENTAL APPROACH Patch clamp measurements of I(K1) were made on cultured adult canine ventricular cardiomyocytes, K(IR)2.1-HEK293 cells and K(IR)2.x inside-out patches. Pentamidine binding to cytoplasmic amino acid residues of K(IR)2.1 channels was studied by molecular modelling. KEY RESULTS Pentamidine application (24 h) decreased I(K1) in cultured canine cardiomyocytes and K(IR)2.1-HEK293 cells under whole cell clamp conditions. Pentamidine inhibited I(K1) in K(IR)2.1-HEK293 cells 10 min after application. When applied to the cytoplasmic side under inside-out patch clamp conditions, pentamidine block of I(K1) was acute (IC(50)= 0.17 microM). Molecular modelling predicted pentamidine-channel interactions in the cytoplasmic pore region of K(IR)2.1 at amino acids E224, D259 and E299. Mutation of these conserved residues to alanine reduced pentamidine block of I(K1). Block was independent of the presence of spermine. K(IR)2.2, and K(IR)2.3 based I(K1) was also sensitive to pentamidine blockade. CONCLUSIONS AND IMPLICATIONS Pentamidine inhibits cardiac I(K1) by interacting with three negatively charged amino acids in the cytoplasmic pore region. Our findings may provide new insights for development of specific I(K1) blocking compounds.
Collapse
Affiliation(s)
- T P de Boer
- Department of Medical Physiology, Division Heart & Lungs, UMCU, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Van Der Heyden MAG, Kok B, Kouwenhoven EN, Tøien Ø, Barnes BM, Fedorov VG, Efimov IR, Opthof T. Cloning, sequence analysis and phylogeny of connexin43 isolated from American black bear heart. ACTA ACUST UNITED AC 2008; 18:380-4. [PMID: 17654014 DOI: 10.1080/10425170701400589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Conduction in the heart requires gap junctions. In mammalian ventricular myocytes these consist of connexin43 (Cx43). Hearts of non-hibernating species display conduction disturbances at reduced temperatures. These may exacerbate into lethal arrhythmias. Hibernating species are protected against these arrhythmias by a non-resolved mechanism. To analyze whether the amino acid composition of Cx43 from the hibernating American black bear displays specific features, we cloned the full coding sequence of Ursus americanus Cx43 and compared with that of other (non)hibernating species. UaCx43 displays 99.7% identity to rabbit Cx43 at the amino acid level. No specific features were observed in UaCx43 when compared to previously cloned Cx43 from hibernating and non-hibernating mammals. Phylogenetic tree reconstruction of this and other published full-length Cx43 sequences reveals a very high level of conservation from fish to men. Finally, one of the previously identified six mammalian characteristic amino acids, is not conserved in the black bear.
Collapse
Affiliation(s)
- Marcel A G Van Der Heyden
- Department of Medical Physiology, Heart Lung Center Utrecht, University Medical Center Utrecht, Utrecht, The Netherlands.
| | | | | | | | | | | | | | | |
Collapse
|
24
|
de Boer TP, van Veen TAB, Bierhuizen MFA, Kok B, Rook MB, Boonen KJM, Vos MA, Doevendans PA, de Bakker JMT, van der Heyden MAG. Connexin43 repression following epithelium-to-mesenchyme transition in embryonal carcinoma cells requires Snail1 transcription factor. Differentiation 2007; 75:208-18. [PMID: 17359298 DOI: 10.1111/j.1432-0436.2006.00133.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Embryonic stem (ES) cells and embryonal carcinoma (EC) cells express high amounts of functional connexin43 (Cx43). During mesoderm formation and subsequent cardiac differentiation, Cx43 is initially down-regulated but is up-regulated again as the emerging cardiomyocytes mature. In this study, we investigated the regulation of Cx43 expression during early phases of differentiation in F9 and P19 EC cells. We found a striking inverse correlation between the expression of Cx43 and that of the transcriptional repressor Snail1. No clear relationship was found with Smad-interacting-protein1 (SIP1), another transcription factor inducing epithelium-to-mesenchyme transition (EMT). Promoter-reporter assays indicated Cx43 repression at the promoter level by ectopically expressed Snail1. To establish whether the Cx43 down-regulation depends on endogenous Snail1, MES-1 cells, differentiated derivatives of P19 EC, were stably transfected by an siRNA construct silencing Snail1 expression. This resulted in a mesenchyme-to-epithelium transition, which was accompanied by increased levels of Cx43 mRNA and protein and enhanced metabolic and electrical coupling. We conclude that Snail1-mediated EMT results in a Cx43 repression.
Collapse
Affiliation(s)
- Teun P de Boer
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
de Boer TP, van Rijen HVM, Van der Heyden MAG, Kok B, Opthof T, Vos MA, Jongsma HJ, de Bakker JMT, van Veen TAB. Beta-, Not Alpha-Adrenergic Stimulation Enhances Conduction Velocity in Cultures of Neonatal Cardiomyocytes. Circ J 2007; 71:973-81. [PMID: 17526999 DOI: 10.1253/circj.71.973] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND During both cardiac maturation and myopathy, elevated levels of circulating catecholamines coincide with alterations in impulse propagation. An in vitro model of cultured cardiomyocytes was used to study the effects of adrenergic stimulation on the conduction characteristics of immature heart cells. METHODS AND RESULTS Neonatal rat cardiomyocytes were cultured on preparations designed to measure conduction velocity (CV). CV was measured on the same preparation twice at t=0 and at t=24 h. Under control conditions (n=7), CV at t=0 (30.9+/-1.9 cm/s) and t=24 (32.4+/-4.4 cm/s) was similar (p=0.70). Immunohistochemistry revealed expression of the gap junction proteins connexin (Cx) 40, Cx43 and Cx45, with Cx43 being highly predominant. Stimulation for 24 h with the beta-adrenergic agonist isoproterenol (ISO) significantly increased CV from 28.0 +/-2.0 cm/s at t=0 to 34.8+/-2.2 cm/s at t=24 (p=0.002, n=5). Microelectrode recordings showed a faster upstroke of the action potential (AP) of ISO-treated cells. Reverse transcribed-polymerase chain reactions (RT-PCR) showed that ISO increased expression of SCN5A and alpha(1c) (alpha-subunit of the cardiac sodium and L-type calcium channel, respectively). Stimulation of cells with ISO did not induce alterations in distribution or expression of Cx40, Cx43 and Cx45 (both mRNA and protein), but slightly increased the phosphorylation of Cx43. Stimulation for 24 h with the alpha-adrenergic agonist phenylephrine did neither affect CV nor the expression of the connexin isoforms, SCN5A and alpha(1c). CONCLUSIONS Alpha- and beta-adrenergic stimulation differently affect propagation of the electric impulse, which is primarily not caused by a differential effect on intercellular coupling. RT-PCR analysis and an enhanced AP upstroke velocity indicate a higher functional expression level of alpha(1c) and SCN5A in beta-adrenergic stimulated cells, which may explain the observed increase in CV.
Collapse
Affiliation(s)
- Teun P de Boer
- Department of Medical Physiology, Heart Lung Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
26
|
de Boer TP, Kok B, Roël G, van Veen TAB, Destrée OHJ, Rook MB, Vos MA, de Bakker JMT, van der Heyden MAG. Cloning, embryonic expression, and functional characterization of two novel connexins from Xenopus laevis. Biochem Biophys Res Commun 2006; 349:855-62. [PMID: 16950205 DOI: 10.1016/j.bbrc.2006.08.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 08/20/2006] [Indexed: 11/26/2022]
Abstract
Vertebrate gap junctions are constituted of connexin (Cx) proteins. In Xenopus laevis, only seven different Cxs have been described so far. Here, we identify two new Cxs from X. laevis. Cx28.6 displays > 60% amino acid identity with human Cx25, Cx29 displays strong homology with mouse Cx26 and Cx30. Cx29 is expressed throughout embryonic development. Cx28.6 mRNA is only transiently found from stage 22 to 26 of development. While no Cx28.6 expression could be detected by whole mount in situ hybridization, expression of Cx29 was found in the developing endoderm, lateral mesoderm, liver anlage, pronephros, and proctodeum. Ectopic expression of Cx28.6 failed to produce functional gap-junctions. In contrast, ectopic expression of full-length Cx29 in HEK293 and COS-7 cells resulted in the formation of gap junction-like structures at the cell-cell interfaces. Ectopic expression of Cx29 in communication deficient N2A cell pairs led to functional electrical coupling.
Collapse
Affiliation(s)
- Teun P de Boer
- Department of Medical Physiology, HLCU, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Firouzi M, Bierhuizen MFA, Kok B, Teunissen BEJ, Jansen AT, Jongsma HJ, Groenewegen WA. The human Cx40 promoter polymorphism -44G-->A differentially affects transcriptional regulation by Sp1 and GATA4. Biochim Biophys Acta 2006; 1759:491-6. [PMID: 17050003 DOI: 10.1016/j.bbaexp.2006.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/05/2006] [Accepted: 09/08/2006] [Indexed: 11/24/2022]
Abstract
Expression of the tissue-specific gap junction protein connexin(Cx)40 is regulated by the interaction of ubiquitous and tissue-specific factors such as Sp1 and GATA4. Cardiac Cx40 expression is altered under pathological conditions such as atrial fibrillation. A human promoter polymorphism, a G-->A change at position -44 that has been associated with atrial-specific arrhythmias, is located between the TBE-NKE-Sp and GATA consensus transcription factor binding sites important for the regulation of the mouse Cx40 gene. The presence of the A-allele at position -44 in promoter-reporter constructs significantly reduces promoter activity. Using electrophoretic mobility shift assays and luciferase reporter assays in various cell types, we show that Sp1 and GATA4 are important regulators of human Cx40 gene transcription and that the -44 G-->A polymorphism negatively affects the promoter regulation by the transcription factors Sp1 and GATA4.
Collapse
Affiliation(s)
- Mehran Firouzi
- Department of Medical Physiology, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
28
|
de Boer TP, van der Heyden MAG, Rook MB, Wilders R, Broekstra R, Kok B, Vos MA, de Bakker JMT, van Veen TAB. Pro-arrhythmogenic potential of immature cardiomyocytes is triggered by low coupling and cluster size. Cardiovasc Res 2006; 71:704-14. [PMID: 16824499 DOI: 10.1016/j.cardiores.2006.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 05/30/2006] [Accepted: 06/01/2006] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Cell transplantation strategies to regenerate compromised myocardium take advance of in vitro generated cardiomyocytes. Common in those immature myocytes is spontaneous impulse formation and a restricted ability to establish proper electrical interaction. Spontaneous impulse formation and impaired cell-to-cell coupling have been shown to be arrhythmogenic. To investigate whether these features harbour a pro-arrhyhmogenic potential for cell transplantation, a co-culture of spontaneously active neonatal rat cardiomyocytes (NRC) and quiescent adult dog cardiomyocytes (ADC) was used. METHODS ADCs and NRCs were isolated and cultured on laminin-coated substrates. Connexin43, N-cadherin and alpha-actinin expression was evaluated with immunohistochemistry. Intercellular coupling was measured in cell pairs using the dual voltage clamp technique and fluorescent dye injection. RESULTS One day after isolation, NRCs were beating spontaneously, while ADCs remained quiescent in monoculture. ADC resting membrane potential was -80.3+/-0.2 mV (mean+/-SEM, N=24) and did not change significantly over time. NRCs had a maximal diastolic potential of -65.0+/-2.8 mV (N=4). After one day of co-culture, pseudopodia-like extensions developed at the former intercalated discs of ADCs, contacting the NRCs. Only ADCs that contacted three or more NRCs started to beat in synchrony. Expression of connexin43 and N-cadherin indicated presence of electrical and mechanical junctions at the interface between the two cell-types. Transfer of Lucifer Yellow demonstrated junctional permeability between ADCs and NRCs. Junctional conductance between ADC-ADC (31.9+/-5.1 nS, N=10) and NRC-NRC (35.0+/-9.6 nS, N=6) pairs was significantly higher compared to ADC-NRC pairs (9.7+/-2.9 nS, N=8). Gap-junctional blockade with halothane reversibly abolished NRC-triggered beating of ADCs. Computer simulations demonstrated that within a delicate 'window' of gap junctional conductance small clusters of spontaneously active cells are able to induce triggered activity in quiescent mature myocytes but also in a two-dimensional sheet of ventricular cells. CONCLUSION Spontaneously active immature cardiomyocytes are able to trigger mature cardiomyocytes depending on their level of electrical coupling and the amount of coupled immature myocytes.
Collapse
Affiliation(s)
- Teun P de Boer
- Heart Lung Center Utrecht, Department of Medical Physiology, Yalelaan 50, 3584 CM Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
de Boer T, van Veen T, Kok B, Bierhuizen M, Rook M, Boonen K, Vos M, Doevendans P, de Bakker J, van der Heyden M. Connexin isoform switching in stem cells undergoing epithelium-to-mesenchyme transition: connexin43 is a direct target of Snail1 transcription factor. J Mol Cell Cardiol 2006. [DOI: 10.1016/j.yjmcc.2006.03.204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
30
|
Firouzi M, Kok B, Spiering W, Busjahn A, Bezzina CR, Ruijter JM, Koeleman BPC, Schipper M, Groenewegen WA, Jongsma HJ, de Leeuw PW. Polymorphisms in human connexin40 gene promoter are associated with increased risk of hypertension in men. J Hypertens 2006; 24:325-30. [PMID: 16508580 DOI: 10.1097/01.hjh.0000200512.40818.47] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Gap junctions, formed by connexins (Cx), are important in the regulation of vascular tone. Previously, we reported two closely linked polymorphisms (-44G --> A and +71A --> G) within regulatory regions of the gene for Cx40, a major connexin in the vascular wall and the kidney. In the present study, we examined the hypothesis that these polymorphic variants are associated with hypertension and that they interact with blood pressure in healthy individuals. METHODS Cx40 genotypes were determined in 191 subjects with essential hypertension, 198 normotensive individuals, and a healthy control population (178 twin pairs, 108 monozygotic, 70 dizygotic). RESULTS We found a significant contribution of the minor Cx40 allele or genotype (-44AA/+71GG) to the risk of hypertension in men (P = 0.013 or P = 0.035; odds ratio, 1.87 or 2.10, respectively), but not in women. Moreover, in the healthy control population a significant effect of Cx40 genotype and sex on systolic blood pressure was found (P < 0.05 and P < 0.0001, respectively). Women carrying the minor Cx40 genotype had significantly higher systolic blood pressure compared with non-carriers (P < 0.05). In men, systolic blood pressure in carriers of the minor Cx40 genotype was not significantly different from the other two genotypes, possibly because of the small number of men in this group. However, men carrying the -44GA/+71AG genotype had higher standing systolic blood pressure compared with the more common Cx40 genotype (-44GG; P = 0.033). CONCLUSION These findings suggest that the Cx40 polymorphisms may form a genetic susceptibility factor for essential hypertension in men.
Collapse
Affiliation(s)
- Mehran Firouzi
- Department of Medical Physiology, University Medical Center, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
De Boer TP, Kok B, Neuteboom KIE, Spieker N, De Graaf J, Destrée OHJ, Rook MB, Van Veen TAB, Jongsma HJ, Vos MA, De Bakker JMT, Van Der Heyden MAG. Cloning and functional characterization of a novel connexin expressed in somites of Xenopus laevis. Dev Dyn 2005; 233:864-71. [PMID: 15895416 DOI: 10.1002/dvdy.20420] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Connexin-containing gap junctions play an essential role in vertebrate development. More than 20 connexin isoforms have been identified in mammals. However, the number identified in Xenopus trails with only six isoforms described. Here, identification of a new connexin isoform from Xenopus laevis is described. Connexin40.4 was found by screening expressed sequence tag databases and carrying out polymerase chain reaction on genomic DNA. This new connexin has limited amino acid identity with mammalian (<50%) connexins, but conservation is higher (approximately 62%) with fish. During Xenopus laevis development, connexin40.4 was first expressed after the mid-blastula transition. There was prominent expression in the presomitic paraxial mesoderm and later in the developing somites. In adult frogs, expression was detected in kidney and stomach as well as in brain, heart, and skeletal muscle. Ectopic expression of connexin40.4 in HEK293 cells, resulted in formation of gap junction like structures at the cell interfaces. Similar ectopic expression in neural N2A cells resulted in functional electrical coupling, displaying mild, asymmetric voltage dependence. We thus cloned a novel connexin from Xenopus laevis, strongly expressed in developing somites, with no apparent orthologue in mammals.
Collapse
Affiliation(s)
- Teun P De Boer
- Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Firouzi M, Ramanna H, Kok B, Jongsma HJ, Koeleman BPC, Doevendans PA, Groenewegen WA, Hauer RNW. Association of human connexin40 gene polymorphisms with atrial vulnerability as a risk factor for idiopathic atrial fibrillation. Circ Res 2004; 95:e29-33. [PMID: 15297374 DOI: 10.1161/01.res.0000141134.64811.0a] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Alterations in distribution, density, and properties of cardiac gap junctions, which mediate electrical coupling of cardiomyocytes, are considered potentially arrhythmogenic. We recently reported 2 linked polymorphisms within regulatory regions of the gene for the atrial gap junction protein connexin40 (Cx40) at nucleotides -44 (G-->A) and +71 (A-->G), which were associated with familial atrial standstill. The present study examined whether these Cx40 polymorphisms were associated with increased atrial vulnerability in vivo and arrhythmia susceptibility. In 30 subjects without structural heart disease, of whom 14 had documented sporadic paroxysmal atrial fibrillation (AF) and 16 had no AF history, inducibility of AF was assessed using an increasingly aggressive atrial stimulation protocol. Coefficient of spatial dispersion of refractoriness (CD) was calculated. CD was defined as the SD of 12 local mean fibrillatory intervals recorded at right atrial sites, expressed as a percentage of the overall mean fibrillatory interval. Cx40 genotypes were determined by direct DNA sequencing. Subjects were stratified according to normal or increased CD with a cutoff value of 3.0, because CD >3.0 was previously shown to be strongly associated with enhanced atrial vulnerability. The prevalence of the minor Cx40 allele (-44A) and -44AA genotype was significantly higher in subjects with increased dispersion (n=13) compared with those with CD < or =3.0 (n=17; P=0.00046 and P=0.025; odds ratios of 6.7 and 7.4) and a control population (n=253; P=0.00002 and P=3.90x10(-7)). Carriers of -44AA genotype had a significantly higher CD compared with those with -44GG genotype (6.37+/-1.21 versus 2.38+/-0.39, P=0.018), whereas heterozygotes had intermediate values (3.95+/-1.38, NS). All subjects with increased CD had a history of idiopathic AF compared with only 1 subject with normal CD. The -44A allele and -44AA genotype were significantly more frequent in subjects with prior AF than in those without (P=0.0019 and P=0.031; odds ratios 5.3 and 6.2). This study provides strong evidence linking Cx40 polymorphisms to enhanced atrial vulnerability and increased risk of AF. The full text of this article is available online at http://circres.ahajournals.org.
Collapse
Affiliation(s)
- Mehran Firouzi
- Department of Medical Physiology,University Medical Center Utrecht, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Radmer R, Kok B. An integrated multi-purpose biology instrument utilizing a single detector, the mass spectrometer. Life Sci Space Res 2002; 10:211-25. [PMID: 11898840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
A mass spectrometer is used to analyze the gas phase in a number of reaction vessels filled with Martian soil. By choosing appropriate incubation conditions this instrument can be used to perform a wide spectrum of experiments ranging from the observation of general indices of life, i.e. processes and patterns unexplainable by physico-chemical mechanisms, to assays utilizing isotopes which probe for specific metabolic processes. Of particular interest is the in situ incubation in which a Martian soil sample is maintained at a constant temperature and its gas phase composition analyzed with time. Properly interpreted, this is a very general life-detection probe which makes minimal assumption as to the nature of Martian biology. Other assays and measurements concerning the soil and the atmosphere compatible with this method are also described.
Collapse
Affiliation(s)
- R Radmer
- Research Institute for Advanced Studies, Baltimore, Md, USA
| | | |
Collapse
|
34
|
Moshage H, Kok B, Huizenga JR, Jansen PL. Nitrite and nitrate determinations in plasma: a critical evaluation. Clin Chem 1995; 41:892-6. [PMID: 7768008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed. In this study the recovery and stability of nitrite and nitrate in whole blood and in plasma, the relation between nitrite and nitrate concentrations in plasma, and possible sources of artifacts were investigated. The main conclusions are: (a) Recovery of nitrite and nitrate from plasma is near-quantitative (87%) and reproducible; (b) nitrite and nitrate are stable in (frozen) plasma for at least 1 year; (c) nitrite in whole blood is very rapidly (> 95% in 1 h) oxidized to nitrate, and therefore plasma nitrite determination alone is meaningless; (d) the ranges of nitrite and nitrate concentrations in plasma samples of 26 healthy persons are 1.3-13 mumol/L (mean 4.2 mumol/L) and 4.0-45.3 mumol/L (mean 19.7 mumol/L), respectively; (e) plasma nitrite and nitrate concentrations were not correlated (nitrite as % of total nitrite + nitrate varied from 3.9% to 88% in plasma samples); and (f) plasma samples should be deproteinized, and background controls for each sample should be included in the assay, to avoid measuring artifactually high nitrite and nitrate concentrations in plasma.
Collapse
Affiliation(s)
- H Moshage
- Department of Medicine, University Hospital Groningen, The Netherlands
| | | | | | | |
Collapse
|
35
|
Abstract
Abstract
Plasma nitrite and nitrate determinations are increasingly being used in clinical chemistry as markers for the activity of nitric oxide synthase and the production of nitric oxide radicals. However, a systematic evaluation of the determination of nitrite and nitrate in plasma has not been performed. In this study the recovery and stability of nitrite and nitrate in whole blood and in plasma, the relation between nitrite and nitrate concentrations in plasma, and possible sources of artifacts were investigated. The main conclusions are: (a) Recovery of nitrite and nitrate from plasma is near-quantitative (87%) and reproducible; (b) nitrite and nitrate are stable in (frozen) plasma for at least 1 year; (c) nitrite in whole blood is very rapidly (> 95% in 1 h) oxidized to nitrate, and therefore plasma nitrite determination alone is meaningless; (d) the ranges of nitrite and nitrate concentrations in plasma samples of 26 healthy persons are 1.3-13 mumol/L (mean 4.2 mumol/L) and 4.0-45.3 mumol/L (mean 19.7 mumol/L), respectively; (e) plasma nitrite and nitrate concentrations were not correlated (nitrite as % of total nitrite + nitrate varied from 3.9% to 88% in plasma samples); and (f) plasma samples should be deproteinized, and background controls for each sample should be included in the assay, to avoid measuring artifactually high nitrite and nitrate concentrations in plasma.
Collapse
Affiliation(s)
- H Moshage
- Department of Medicine, University Hospital Groningen, The Netherlands
| | - B Kok
- Department of Medicine, University Hospital Groningen, The Netherlands
| | - J R Huizenga
- Department of Medicine, University Hospital Groningen, The Netherlands
| | - P L Jansen
- Department of Medicine, University Hospital Groningen, The Netherlands
| |
Collapse
|
36
|
Abstract
The primary photochemical quencher Q and the secondary electron acceptor pool in Photosystem II have been titrated. We used particles of Scenedesmus mutant No. 8 that lack System I and allowed the system to equilibrate with external redox mediators in darkness prior to measurement of the fluorescence rise curve. The titration of Q, as indicated by the dark level of Fi, occurs in two discrete steps. The high-potential component (Qh) has a midpoint potential of +68 mV (pH 7.2) and accounts for approximately 67% of Q. The pH sensitivity of the midpoint potential is -60 mV, indicating the involvement of 1 H+/e. The low-potential component (Q1) accounts for the remaining 33% of Q and shows a midpoint potential near--300 mV (pH 7.2). The plastoquinone pool, assayed as the half-time of the fluorescence rise curve, titrates as a single component with a midpoint potential 30--40 mV more oxidizing than that of Qh, i.e., at 106 mV (pH 7.2). The Em shows a pH sensitivity of -60 mV/pH unit, indicating the involvement of 1 H+/e. The observation that all 12--14 electron equivalents in the pool titrate as a single component indicates that the heterogeneity otherwise observed in the secondary acceptor system is a kinetic rather than a thermodynamic property. Illumination causes peculiar, and as yet unclarified, changes of both Q and the secondary pool under anaerobic conditions that are reversed by oxygen.
Collapse
|
37
|
Golbeck JH, Velthuys BR, Kok B. Evidence that the intermediate electron acceptor, A2, in photosystem I is a bound iron-sulfur protein. Biochim Biophys Acta 1978; 504:226-30. [PMID: 708722 DOI: 10.1016/0005-2728(78)90020-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Absorption changes accompanying the formation of light-induced P-700+ were investigated in a highly enriched Photosystem I preparation where an intermediate electron acceptor preceding P-430 could be detected. In an enriched Photosystem I particle, light-induced reversible absorption changes observed at 700 nm in the presence of dithionite resembled those previously seen at 703 nm and 820 nm [9], thus indicating the presence of a backreaction between P700+ and A-2. After this same Photosystem I particle was treated to denature the bound iron-sulfur centers, the photochemical changes that could be attributed to P-700 in equilibrium A2 were completely lost. These results provide evidence that the intermediate electron acceptor, A2, is a bound iron-sulfur protein. Additional studies in the 400--500 nm region with Photosystem I particles prepared by sonication indicate that the spectrum of A2 is different from that of P-430.
Collapse
|
38
|
Hardt H, Kok B. Comparison of photosynthetic activities of spinach chloroplasts with those of corn mesophyll and corn bundle sheath tissue. Plant Physiol 1978; 62:59-63. [PMID: 16660469 PMCID: PMC1092055 DOI: 10.1104/pp.62.1.59] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Bundle sheath and mesophyll chloroplasts from Zea mays showed comparable rates of O(2) evolution, which amounted to about half of the rate observed in spinach (Spinacia oleracea) chloroplasts.Ratios of 4.5, 4.6, and 6.2 Mn(2+) atoms per 400 chlorophylls were observed in mesophyll, bundle sheath, and spinach chloroplasts, respectively. These ratios roughly correspond to the observed O(2) evolution rates.Rates of electron transport from water to methylviologen (photosystem I and II) in both types of corn chloroplasts were about one-third that in spinach. Compared to spinach, transport rates from reduced diaminodurene to methylviologen (photosystem I) were about one-third and greater than one-half in mesophyll and bundle sheath material, respectively.In both types of corn chloroplasts, electron flow from photosystem II to P700 was abnormal. This observation, together with the low rates of all activities, suggests that damage occurred during isolation. Such damage may limit the quantitative significance of observations made with these materials (including the following data).Measurements of flash yields of O(2) evolution or O(2) uptake showed that the size of the photosynthetic unit was the same in photosystems I and II and in all three types of chloroplasts (about 400 chlorophylls per equivalent).Similarity of the photochemical cross-section of the two photosystems in the three preparations was also found in optical experiments: that is the half-times of the fluorescence rise in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (photosystem II) and of the photooxidation of P700 (photosystem I).The ratio of P700 to chlorophyll appeared to be about 2-fold higher in bundle sheath chloroplasts than in the other materials (1/200 versus 1/400).
Collapse
Affiliation(s)
- H Hardt
- Martin Marietta Laboratories, 1450 South Rolling Road, Baltimore, Maryland 21227
| | | |
Collapse
|
39
|
Golbeck JH, Kok B. Further studies of the membrane--bound iron--sulfur proteins and P700 in a photosystem I subchloroplast particle. Arch Biochem Biophys 1978; 188:233-42. [PMID: 209749 DOI: 10.1016/s0003-9861(78)80005-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
40
|
Radmer R, Kok B, Ollinger O. Kinetics and Apparent K(m) of Oxygen Cycle under Conditions of Limiting Carbon Dioxide Fixation. Plant Physiol 1978; 61:915-7. [PMID: 16660425 PMCID: PMC1092011 DOI: 10.1104/pp.61.6.915] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A mass spectrometer with a membrane inlet was used to monitor light-driven O(2) evolution, O(2) uptake, and CO(2) uptake in suspensions of algae (Scenedesmus obliquus). We observed the following. (a) The rate of O(2) uptake, which, in the presence of iodoacetamide, replaces the uptake of CO(2), showed a distinct plateau (V(max)) beyond approximately 30% O(2) and was half-maximal at approximately 8% O(2). We concluded that this light-driven O(2) uptake process, which does not involve carbon compounds, is saturated at lower O(2) concentrations than are photorespiration and glycolate formation. (b) In the absence of inhibitor, O(2) evolution was relatively unaffected by the presence or absence of CO(2). During the course of CO(2) depletion, electron flow to CO(2) was replaced by an equivalent flow to O(2). (c) There was a distinct delay between the cessation of CO(2) uptake and the increase in O(2) uptake. We ascribe this delay to the transient utilization of another electron acceptor-possibly bicarbonate or another bound form of CO(2).
Collapse
Affiliation(s)
- R Radmer
- Martin Marietta Laboratories, 1450 South Rolling Road, Baltimore, Maryland 21227
| | | | | |
Collapse
|
41
|
Abstract
A study was made of the interactions of flash-illuminated chloroplasts with hydrogen peroxide. We conclude: 1. The oxygen precursor system can be reduced beyond the S0 state to an S-1 state, which can be oxidized to S0 by a single flash. 2. In the dark, a two-electron donation by H2O2 takes place which reduces S2 to S0 and S1 to S-1. 3. At the same time, two-electron oxidations by H2O2 re-form, S2 from S0 and S1 from S-1. 4. The catalase-like activity due to this cyclic oxidation and reduction of the S enzyme is higher with the S2 in equilibrium S0 couple than with the S1 in equilibrium S-1 couple. Another process, however, is responsible for most of the O2 evolution from H2O2 in the light. Our evidence indicates that this process: (1) is independent of the S states and insensitive to Tris washing, (2) turns over rapidly in high concentrations of peroxide, (3) yields 1 O2 per electron passing through system II; (4) dismutates two H2O2 molecules, so that there is no net consumption of 'holes'.
Collapse
|
42
|
Abstract
Treatment of spinach chloroplasts with glutaraldehyde causes an inhibition in the electron transport chain between the two photosystems. Measurements of O(2) flash yields, pH exchange, and fluorescence induction show that the O(2) evolving apparatus, photosystem II and its electron acceptor pool are not affected. The behavior of P700 indicates that its reduction but not its oxidation, is severely inhibited. Cytochrome f is still reducible by photosystem II but also slowly oxidizable by photosystem I. The sensitivity of isolated plastocyanin to glutaraldehyde further supports the conclusion that glutaraldehyde inhibits at the plastocyanin level and thereby induces a break between P700 and cytochrome f.
Collapse
Affiliation(s)
- H Hardt
- Martin Marietta Laboratories, 1450 South Rolling Road, Baltimore, Maryland 21227
| | | |
Collapse
|
43
|
Abstract
Treatment of isolated chloroplasts with glutaraldehyde affects their ability to photoreduce artificial electron acceptors. The remaining rate of O2 evolution approaches zero with methyl viologen, is low with ferricyanide, but nearly normal with lipophilic Photosystem II acceptors, like oxidized p-phenylenediamine and oxidized diaminodurene. Since Photosystem I donor reactions are also affected, a specific site of inhibition of electron transport to Photosystem I is indicated. At the same time, glutaraldehyde prolongs the longevity of the chloroplasts stored in dark. In control samples the half-life of Photosystem II activity varied between 5 days at 4degreesC and 1 day at 25degreesC. Glutaraldehyde treatment increased these half times approx. 3-fold. The glutaraldehyde doses required to induce inhibition and stabilization were very similar.
Collapse
|
44
|
Abstract
A mass spectrometer with a membrane inlet system was used to monitor directly gaseous components in a suspension of algae. Using labeled oxygen, we observed that during the first 20 seconds of illumination after a dark period, when no net O(2) evolution or CO(2) uptake was observed, O(2) evolution was normal but completely compensated by O(2) uptake. Similarly, when CO(2) uptake was totally or partially inhibited, O(2) evolution proceeded at a high (near maximal) rate. Under all conditions, O(2) uptake balanced that fraction of the O(2) evolution which could not be accounted for by CO(2) uptake.From these observations we concluded that O(2) and CO(2) are in direct competition for photosynthetically generated reducing power, with O(2) being the main electron acceptor during the induction process and under other conditions in which CO(2) reduction cannot keep pace with O(2) evolution. The high rate of the O(2) uptake reaction observed in the presence of iodoacetamide, KCN, or carbonyl cyanide p-trifluoromethyoxyphenylhydrazone, suggests that a special high capacity oxidase distinct from ribulose diphosphate oxygenase exists in whole cells. The rapid reduction of molecular O(2) after a period of darkness probably serves as a priming reaction for the photosynthetic apparatus. The high steady state rate of the O(2) cycle in the absence of CO(2) fixation suggests that the regulation of photosynthesis does not involve significant changes in the rate of photochemical electron transport.
Collapse
Affiliation(s)
- R J Radmer
- Martin Marietta Laboratories, Baltimore, Maryland 21227
| | | |
Collapse
|
45
|
Abstract
Using a rapid pH electrode, measurements were made of the flash-induced proton transport in isolated spinach chloroplasts. To calibrate the system, we assumed that in the presence of ferricyanide and in steady-state flashing light, each flash liberates from water one proton per reaction chain. We concluded that with both ferricyanide and methylviologen as acceptors two protons per electron are translocated by the electron transport chain connecting Photosystem II and I. With methyl viologen but not with ferricyanide as an acceptor, two additional protons per electron are taken up due to Photosystem I activity. One of these latter protons is translocated to the inside of the thylakoid while the other is taken up in H2O2 formation. Assuming that the proton released during water splitting remains inside the thylakoid, we compute H+/e- ratios of 3 and 4 for ferricyanide and methylviologen, respectively. In continuous light of low intensity, we obtained the same H+/e- ratios. However, with higher intensities where electron transport becomes rate limited by the internal pH, the H+/e- ratio approached 2 as a limit for both acceptors. A working model is presented which includes two sites of proton translocation, one between the photoacts, the other connected to Photosystem I, each of which translocates two protons per electron. Each site presents a approximately 30 ms diffusion barrier to proton passage which can be lowered by uncouplers to 6-10 ms.
Collapse
|
46
|
|
47
|
|
48
|
|
49
|
|
50
|
Radmer R, Kok B. A kinetic analysis of the oxidizing and reducing sides of the O2-evolving system of photosynthesis. Biochim Biophys Acta 1973; 314:28-41. [PMID: 4741592 DOI: 10.1016/0005-2728(73)90061-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|