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Huang R, Shi J, Wei R, Li J. Challenges of insulin-like growth factor-1 testing. Crit Rev Clin Lab Sci 2024; 61:388-403. [PMID: 38323343 DOI: 10.1080/10408363.2024.2306804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 12/27/2023] [Accepted: 01/15/2024] [Indexed: 02/08/2024]
Abstract
Insulin-like growth factor 1 (IGF-1), primarily synthesized in the liver, was initially discovered due to its capacity to replicate the metabolic effects of insulin. Subsequently, it emerged as a key regulator of the actions of growth hormone (GH), managing critical processes like cell proliferation, differentiation, and apoptosis. Notably, IGF-1 displays a longer half-life compared to GH, making it less susceptible to factors that may affect GH concentrations. Consequently, the measurement of IGF-1 proves to be more specific and sensitive when diagnosing conditions such as acromegaly or GH deficiency. The recognition of the existence of IGFBPs and their potential to interfere with IGF-1 immunoassays urged the implementation of various techniques to moderate this issue and provide accurate IGF-1 results. Additionally, in response to the limitations associated with IGF-1 immunoassays and the occurrence of discordant IGF-1 results, modern mass spectrometric methods were developed to facilitate the quantification of IGF-1 levels. Taking advantage of their ability to minimize the interference caused by IGF-1 variants, mass spectrometric methods offer the capacity to deliver robust, reliable, and accurate IGF-1 results, relying on the precision of mass measurements. This also enables the potential detection of pathogenic mutations through protein sequence analysis. However, despite the analytical challenges, the discordance in IGF-1 reference intervals can be attributed to a multitude of factors, potentially leading to distinct interpretations of results. The establishment of reference intervals for each assay is a demanding task, and it requires nationwide multicenter collaboration among laboratorians, clinicians, and assay manufacturers to achieve this common goal in a cost-effective and resource-efficient manner. In this comprehensive review, we examine the challenges associated with the standardization of IGF-1 measurement methods, the minimization of pre-analytical factors, and the harmonization of reference intervals. Particular emphasis will be placed on the development of IGF-1 measurement techniques using "top-down" or "bottom-up" mass spectrometric methods.
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Affiliation(s)
- Rongrong Huang
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Department of Pathology and Laboratory Medicine, Harris Health System Ben Taub Hospital, Houston, TX, USA
| | - Junyan Shi
- Department of Pathology and Laboratory Medicine, Vancouver General Hospital, Vancouver Coastal Health, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ruhan Wei
- Department of Pathology, Duke University School of Medicine, Durham, NC, USA
| | - Jieli Li
- Department of Pathology, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
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Paragliola RM, Carrozza C, Corsello SM, Salvatori R. The biochemical diagnosis of acromegaly: revising the role of measurement of IGF-I and GH after glucose load in 5 questions. Expert Rev Endocrinol Metab 2022; 17:205-224. [PMID: 35485763 DOI: 10.1080/17446651.2022.2069558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/20/2022] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Acromegaly is a rare disorder characterized by the excessive secretion of growth hormone (GH), mostly caused by pituitary adenomas. While in full-blown cases the diagnosis is easy to establish, milder cases are more challenging. Additionally, establishing whether full cure after surgery is reached may be difficult. AREAS COVERED In this article, we will review the challenges posed by the variability in measurements of GH and its main effector insulin-like growth factor I (IGF-I) due to both biological changes, co-morbidities, and assays variability. EXPERT OPINION Interpretation of GH and IGF-I assays is important in establishing an early diagnosis of acromegaly, in avoiding misdiagnosis, and in establishing if cure is achieved by surgery. Physicians should be familiar with the variables that affect measurements of these 2 hormones, and with the performance of the assays available in their practice.
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Affiliation(s)
- Rosa Maria Paragliola
- Unit of Endocrinology, Department of Translational Medicine and Surgery - Universita' Cattolica del Sacro Cuore, Fondazione Policlinico "Gemelli", IRCCS, Rome, Italy
| | - Cinzia Carrozza
- Unit of Chemistry, Biochemistry and Clinical Molecular Biology - Università Cattolica Del Sacro Cuore, Fondazione Policlinico "Gemelli," IRCCS, Rome, Italy
| | - Salvatore M Corsello
- Unit of Endocrinology, Department of Translational Medicine and Surgery - Universita' Cattolica del Sacro Cuore, Fondazione Policlinico "Gemelli", IRCCS, Rome, Italy
- UniCamillus-Saint Camillus International University of Health Sciences, Rome, Italy
| | - Roberto Salvatori
- Division of Endocrinology Diabetes and Metabolism and Pituitary Center, Johns Hopkins University, Baltimore MD, USA
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Meshkini F, Ramezani‐Jolfaie N, Sargazi S, Clark CC, Soltani S. The effects of lycopene supplementation on
insulin‐like
growth factor‐1 and
insulin‐like
growth factor binding proteins: A systematic review of randomized controlled trials. Phytother Res 2022; 36:1633-1643. [DOI: 10.1002/ptr.7418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 01/23/2022] [Accepted: 01/29/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Fatemeh Meshkini
- Department of Biochemistry, School of medicine Shahid Sadoughi University of Medical Sciences Yazd Iran
- Student Research Committee Shahid Sadoughi University of Medical Sciences Yazd Iran
| | - Nahid Ramezani‐Jolfaie
- Department of Community Medicine, School of Medicine Hormozgan University of Medical Sciences Bandar Abbas Iran
| | - Saman Sargazi
- Cellular and Molecular Research Center, Research Institute of Cellular and Molecular Sciences in Infectious Diseases Zahedan University of Medical Sciences Zahedan Iran
| | - Cain C.T. Clark
- Faculty Research Centre for Intelligent Healthcare Coventry University Coventry UK
| | - Sepideh Soltani
- Yazd Cardiovascular Research Center, Non‐communicable Diseases Research Institute Shahid Sadoughi University of Medical Sciences Yazd Iran
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Gaddas M. Le dosage de l’Insulin-Like Growth Factor-1 : les difficultés de la détermination sérique et de l’interprétation des résultats. NUTR CLIN METAB 2022. [DOI: 10.1016/j.nupar.2021.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Cowan DA, Moncrieffe DA. Procollagen type III amino-terminal propeptide and insulin-like growth factor I as biomarkers of growth hormone administration. Drug Test Anal 2021; 14:808-819. [PMID: 34418311 PMCID: PMC9545871 DOI: 10.1002/dta.3155] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 01/19/2023]
Abstract
The acceptance in 2012 by the World Anti‐Doping Agency (WADA) of the biomarker test for human growth hormone (hGH) based on procollagen type III amino‐terminal propeptide (P‐III‐NP) and insulin‐like growth factor I (IGF‐I) was perhaps the first time that such a method has been used for forensic purposes. Developing a biomarker test to anti‐doping standards, where the strict liability principle applies, is discussed. An alternative WADA‐accepted approach is based on the measurement of different hGH isoforms, a method that suffers from the very short half‐life of hGH limiting the detection period. Modification or withdrawal of the immunoassays, on which the biomarker measurements largely depend, has necessitated revalidation of the assays, remeasurement of samples and adjustment of the decision limits above which an athlete will be assumed to have administered hGH. When a liquid chromatography coupled mass spectrometry (LC–MS) method became a reality for the measurement of IGF‐I, more consistency of results was assured. Measurement of P‐III‐NP is still dependent on immunoassays although work is underway to develop an LC–MS method. The promised long‐term detection time for the biomarker assay does not appear to have been realised in practice, and this is perhaps partly the result of decision limits being set too high. Nevertheless, more robust assays are needed before a further adjustment of the decision limit is warranted. In the meantime, WADA is considering using P‐III‐NP and IGF‐I as components of a biomarker passport system recording data from an individual athlete, rather than the population. Using this approach, smaller perturbations in the growth hormone (GH) score would mandate an investigation and possible action for hGH administration.
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Affiliation(s)
- David A Cowan
- Department of Analytical, Environmental and Forensic Science, King's College London, London, UK
| | - Danielle A Moncrieffe
- Department of Analytical, Environmental and Forensic Science, King's College London, London, UK.,Drug Control Centre, Department of Analytical, Environmental and Forensic Science, King's College London, London, UK
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6
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Schaefer S, Kooistra HS, Riond B, Suchodolski JS, Steiner JM, Prins M, Zini E, Reusch CE. Evaluation of insulin-like growth factor-1, total thyroxine, feline pancreas-specific lipase and urinary corticoid-to-creatinine ratio in cats with diabetes mellitus in Switzerland and the Netherlands. J Feline Med Surg 2017; 19:888-896. [PMID: 27578200 PMCID: PMC11104121 DOI: 10.1177/1098612x16664390] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
Objectives The aim of the study was to evaluate circulating insulin-like growth factor-1 (IGF-1), feline pancreas-specific lipase (fPLI) and total thyroxine (TT4) concentrations and urinary corticoid-to-creatinine ratio (UCCR) as indicators for the prevalence of acromegaly, pancreatitis, hyperthyroidism and hypercortisolism in cats with diabetes mellitus. Methods Blood and urine samples were collected from diabetic cats treated in primary care clinics in Switzerland and the Netherlands. Standardised questionnaires and physical examination forms provided clinical information from owners and veterinarians. Laboratory testing included serum biochemistry profile analysis and measurement of circulating fructosamine, IGF-1, fPLI, and TT4 concentrations and UCCR. CT of the pituitary gland was performed using a multidetector computed tomography scanner. Results Blood samples were available from 215 cats and urine samples were collected at home from 117 cats. Age ranged from 2-18 years (median 12 years) and body weight from 2.7-12.3 kg (median 5.5 kg). Sixty-five percent of the cats were castrated male and 35% were female (33% spayed); 82% were domestic shorthair cats. Eighty percent of cats received a porcine insulin zinc suspension, 19.5% insulin glargine and 0.5% a human neutral protamine hagedorn insulin. Thirty-six of 202 (17.8%) cats had IGF-1 concentrations >1000 ng/ml. Serum fPLI, and TT4 concentrations and UCCR were increased in 86/196 (43.9%), 9/201 (4.5%) and 18/117 cats (15.3%), respectively. Prevalence did not differ between countries. Conclusions Hyperthyroidism is rare, whereas increased fPLI concentration, possibly reflecting pancreatitis, is common in diabetic cats. The high UCCR may reflect activation of the hypothalamus-pituitary-adrenal axis, which also occurs in diabetic humans. The percentage of cats with increased IGF-1 was high but lower than reported in recent studies.
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Affiliation(s)
- Sandra Schaefer
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Hans S Kooistra
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Barbara Riond
- Clinical Laboratory, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Jan S Suchodolski
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, Texas A&M University, College Station, TX, USA
| | - Jörg M Steiner
- Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, Texas A&M University, College Station, TX, USA
| | - Marrit Prins
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Eric Zini
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
- Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Italy
- The Veterinary Institute of Novara, Granozzo con Monticello, Italy
| | - Claudia E Reusch
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Aneke-Nash CS, Dominguez-Islas C, Bůžková P, Qi Q, Xue X, Pollak M, Strickler HD, Kaplan RC. Agreement between circulating IGF-I, IGFBP-1 and IGFBP-3 levels measured by current assays versus unavailable assays previously used in epidemiological studies. Growth Horm IGF Res 2016; 26:11-16. [PMID: 26774400 PMCID: PMC4724357 DOI: 10.1016/j.ghir.2015.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 11/30/2015] [Accepted: 12/06/2015] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Levels of insulin-like growth factor (IGF) proteins are associated with the risk of cancer and mortality. IGF assays produced by Diagnostic Systems Laboratories (DSL) were widely used in epidemiological studies, were not calibrated against recommended standards and are no longer commercially available. DESIGN In a split sample study among 1471 adults participating in the Cardiovascular Health Study, we compared values obtained using DSL assays with alternative assays for serum IGF-I (Immunodiagnostic Systems, IDS), IGFBP-1 (American Laboratory Products Company, ALPCO) and IGFBP-3 (IDS). RESULTS Results were compared using kernel density estimation plots, quartile analysis with weighted kappa statistics and linear regression models to assess the concordance of data from the different assays. Participants had a mean age of 77years. Results between alternative assays were strongly correlated (IGF-I, r=0.93 for DSL versus IDS; log-IGFBP-1, r=0.90 for DSL versus ALPCO; IGFBP-3, r=0.92 for DSL versus IDS). Cross tabulations showed that participants were usually in the same quartile categories regardless of the assay used (overall agreement, 74% for IGF-I, 64% for IGFBP-1, 71% for IGFBP-3). Weighted kappa also showed substantial agreement between assays (kw, 0.78 for IGF-I, 0.69 for IGFBP-1, 0.76 for IGFBP-3). Regressions of levels obtained with DSL assays (denoted X) to alternative assays were, IGF-I: 0.52X+15.2ng/ml, log-IGFBP-1: 1.01X-1.73ng/ml IGFBP-3: 0.87X+791.1ng/ml. Serum values of IGF-I, IGFBP-1 and IGFBP-3 measured using alternative assays are moderately correlated. CONCLUSIONS Care is needed in the interpretation of data sets involving IGF analytes if assay methodologies are not uniform.
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Affiliation(s)
- Chino S Aneke-Nash
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States.
| | | | - Petra Bůžková
- Department of Biostatistics, University of Washington, Seattle, WA, United States
| | - Qibin Qi
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Xiaonan Xue
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Michael Pollak
- Department of Medicine and Oncology, McGill University, Montreal, Quebec, Canada
| | - Howard D Strickler
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Robert C Kaplan
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States
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Palta M, LeCaire T, Sadek-Badawi M, Herrera V, Danielson KK. The trajectory of IGF-1 across age and duration of type 1 diabetes. Diabetes Metab Res Rev 2014; 30:777-83. [PMID: 24845759 PMCID: PMC4236234 DOI: 10.1002/dmrr.2554] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/07/2014] [Indexed: 01/18/2023]
Abstract
BACKGROUND Individuals with type 1 diabetes may have low IGF-1, related to insulinopenia and insulin resistance. There are few longitudinal studies of IGF-1 levels to establish its pattern in type 1 diabetes with duration and age, and to examine whether IGF-1 tracks within individuals over time. We examine age and duration trends, and the relationship of IGF-1 to gender, glycaemic control, insulin level and other factors. METHODS Participants in the Wisconsin Diabetes Registry Study, an incident cohort study of type 1 diabetes diagnosed May 1987-April 1992, were followed for up to 18 years with IGF-1 samples up to age 45 for women and age 37 for men. RESULTS IGF-1 is lower with type 1 diabetes than in normative samples. Although, the pattern across age resembles that in normative samples with a peak in adolescence and slow decline after age 20, the adolescent peak is delayed for women with type 1 diabetes. There was low to moderate tracking of IGF-1 within an individual. Higher insulin dose was associated with higher IGF-1 as was puberty, and female gender. Adjusted for these factors, IGF-1 declined rapidly across early diabetes duration. Lower HbA1c was most strongly related to higher IGF-1 at Tanner stages 1 and 2. CONCLUSIONS IGF-1 is low in type 1 diabetes, with a delayed adolescent peak in women and is especially influenced by glycaemic control in early and pre-adolescence. High variability within an individual is likely a challenge in investigating associations between IGF-1 and long-term outcomes, and may explain contradictory findings.
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Affiliation(s)
- Mari Palta
- Department of Population Health Sciences, University of Wisconsin, Madison, WI
- Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, WI
| | - Tamara LeCaire
- Department of Population Health Sciences, University of Wisconsin, Madison, WI
| | - Mona Sadek-Badawi
- Department of Population Health Sciences, University of Wisconsin, Madison, WI
| | - Victor Herrera
- Facultad de Ciencias de la Salud, Universidad Autónoma de Bucaramanga, Bucaramanga, Colombia
| | - Kirstie K. Danielson
- Division of Epidemiology and Biostatistics, University of Illinois School of Public Health, Chicago, IL
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Lopes F, Cowan DA, Thevis M, Thomas A, Parkin MC. Quantification of intact human insulin-like growth factor-I in serum by nano-ultrahigh-performance liquid chromatography/tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1426-1432. [PMID: 24861591 DOI: 10.1002/rcm.6908] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 03/26/2014] [Accepted: 03/27/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE Insulin-like growth factor-I is one of the biomarkers used to detect growth hormone administration prohibited in human sport. Current testing approaches for IGF-I rely on commercial immunoassays, which may change from time to time requiring complex revalidation. Mass spectrometry (MS)-based approaches often rely on enzymatically digesting the protein and measuring specific peptide concentrations. In order to reinforce the current available methodology for IGF-I testing, a reliable and equally sensitive MS method is required for the analysis of intact protein using small sample volumes (<25 μL). METHODS IGF-I was extracted from human serum samples by a simple protein precipitation procedure. Separation was achieved via nano-ultrahigh-performance liquid chromatography and MS analysis was conducted by nano-electrospray ionisation triple-quadrupole mass spectrometry in the selected reaction monitoring mode using a stable-isotope-labelled internal standard. RESULTS A six-point calibration curve ranging from 50 to 1000 ng/mL of human IGF-I in rat serum was used to establish instrument response. The method provided a limit of quantification of 50 ng/mL, with intra- and inter-day precision ≤5% and intra- and inter-day accuracy ≥95%. CONCLUSIONS A quantitative method was developed for the quantification of intact IGF-I in human serum samples. The data generated provided important information for the development of a new reference method for the growth hormone biomarker test and helped create a reliable system for monitoring peptide hormones in individual athletes, a possible extension to the athlete biological passport system. Nano-electrospray has here been shown to be sufficiently robust for routine use in an analytical laboratory, allowing for the analysis of minute sample volumes.
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Affiliation(s)
- Filipe Lopes
- King's College London, Analytical and Environmental Science Division, Drug Control Centre, 150 Stamford Street, London, SE1 9NH, UK
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Serum insulin-like growth factor-I, iron, C-reactive protein, and serum amyloid A for prediction of outcome in dogs with pyometra. Theriogenology 2014; 82:43-8. [DOI: 10.1016/j.theriogenology.2014.02.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/11/2014] [Accepted: 02/20/2014] [Indexed: 12/19/2022]
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Ramadhin C, Pillay B, Olaniran AO. Cell-based assays for IGF-I bioactivity measurement: overview, limitations and current trends. Growth Factors 2014; 32:130-8. [PMID: 25060037 DOI: 10.3109/08977194.2014.939806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Insulin-like growth factor-I (IGF-I) is an important growth promoting protein that is involved in numerous cellular responses and multiple biological systems. Although the molecular structure, function and recombinant production of IGF-I in various hosts have been the subject of much researches over the recent past, methods to determine the bioactivity of this protein have not been fully explored. Several assays have traditionally been used to measure IGF-I bioactivity, but have not become a routine laboratory practice due to the high cost involved and technical problems. Thus, there is still a need for a rapid, technically simple and accurate assay to determine IGF-I bioactivity. This review highlights the various cell-based assays currently commercially available for measuring the bioactivity of IGF-I along with their limitations. This is aimed at presenting the modern-day IGF researcher with a holistic overview of the current trends and future prospects regarding IGF-I bioactivity determinations.
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Affiliation(s)
- Charlotte Ramadhin
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal , Durban , Republic of South Africa
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Varewijck AJ, van der Lely AJ, Neggers SJCMM, Lamberts SWJ, Hofland LJ, Janssen JAMJL. In active acromegaly, IGF1 bioactivity is related to soluble Klotho levels and quality of life. Endocr Connect 2014; 3:85-92. [PMID: 24692508 PMCID: PMC4001616 DOI: 10.1530/ec-14-0028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The value of measuring IGF1 bioactivity in active acromegaly is unknown. Soluble Klotho (S-Klotho) level is elevated in active acromegaly and it has been suggested that S-Klotho can inhibit activation of the IGF1 receptor (IGF1R). A cross-sectional study was carried out in 15 patients with active acromegaly based on clinical presentation, unsuppressed GH during an oral glucose tolerance test, and elevated total IGF1 levels (>+2 s.d.). Total IGF1 was measured by immunoassay, IGF1 bioactivity by the IGF1R kinase receptor activation assay and S-Klotho by an ELISA. Quality of Life (QoL) was assessed by Acromegaly QoL (AcroQoL) Questionnaire and Short-Form-36 Health Survey Questionnaire (SF-36). Out of 15 patients, nine had IGF1 bioactivity values within the reference range. S-Klotho was higher in active acromegaly compared with controls. Age-adjusted S-Klotho was significantly related to IGF1 bioactivity (r=0.75, P=0.002) and to total IGF1 (r=0.62, P=0.02). IGF1 bioactivity and total IGF1 were inversely related to the physical component summary of the SF-36 (r=-0.78, P=0.002 vs r=-0.60, P=0.03). Moreover, IGF1 bioactivity, but not total IGF1, was significantly inversely related to the physical dimension of the AcroQoL Questionnaire (r=-0.60, P=0.02 vs r=-0.37, P=0.19). In contrast to total IGF1, IGF1 bioactivity was within the reference range in a considerable number of subjects with active acromegaly. Elevated S-Klotho levels may have reduced IGF1 bioactivity. Moreover, IGF1 bioactivity was more strongly related to physical measures of QoL than total IGF1, suggesting that IGF1 bioactivity may better reflect physical limitations perceived in active acromegaly.
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Oei L, Zillikens MC, Dehghan A, Buitendijk GHS, Castaño-Betancourt MC, Estrada K, Stolk L, Oei EHG, van Meurs JBJ, Janssen JAMJL, Hofman A, van Leeuwen JPTM, Witteman JCM, Pols HAP, Uitterlinden AG, Klaver CCW, Franco OH, Rivadeneira F. High bone mineral density and fracture risk in type 2 diabetes as skeletal complications of inadequate glucose control: the Rotterdam Study. Diabetes Care 2013; 36:1619-28. [PMID: 23315602 PMCID: PMC3661786 DOI: 10.2337/dc12-1188] [Citation(s) in RCA: 272] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Individuals with type 2 diabetes have increased fracture risk despite higher bone mineral density (BMD). Our aim was to examine the influence of glucose control on skeletal complications. RESEARCH DESIGN AND METHODS Data of 4,135 participants of the Rotterdam Study, a prospective population-based cohort, were available (mean follow-up 12.2 years). At baseline, 420 participants with type 2 diabetes were classified by glucose control (according to HbA1c calculated from fructosamine), resulting in three comparison groups: adequately controlled diabetes (ACD; n = 203; HbA1c <7.5%), inadequately controlled diabetes (ICD; n = 217; HbA1c ≥ 7.5%), and no diabetes (n = 3,715). Models adjusted for sex, age, height, and weight (and femoral neck BMD) were used to test for differences in bone parameters and fracture risk (hazard ratio [HR] [95% CI]). RESULTS The ICD group had 1.1-5.6% higher BMD, 4.6-5.6% thicker cortices, and -1.2 to -1.8% narrower femoral necks than ACD and ND, respectively. Participants with ICD had 47-62% higher fracture risk than individuals without diabetes (HR 1.47 [1.12-1.92]) and ACD (1.62 [1.09-2.40]), whereas those with ACD had a risk similar to those without diabetes (0.91 [0.67-1.23]). CONCLUSIONS Poor glycemic control in type 2 diabetes is associated with fracture risk, high BMD, and thicker femoral cortices in narrower bones. We postulate that fragility in apparently "strong" bones in ICD can result from microcrack accumulation and/or cortical porosity, reflecting impaired bone repair.
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Affiliation(s)
- Ling Oei
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
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Tschuor F, Zini E, Schellenberg S, Wenger M, Boretti FS, Reusch CE. Evaluation of four methods used to measure plasma insulin-like growth factor 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. Am J Vet Res 2013; 73:1925-31. [PMID: 23176419 DOI: 10.2460/ajvr.73.12.1925] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate 4 methods used to measure plasma insulin-like growth factor (IGF) 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. ANIMALS 39 healthy cats, 7 cats with diabetes mellitus, and 33 cats with other diseases. PROCEDURES 4 assays preceded by different sample preparation methods were evaluated, including acid chromatography followed by radioimmunoassay (AC-RIA), acid-ethanol extraction followed by immunoradiometry assay (AEE-IRMA), acidification followed by immunochemiluminescence assay (A-ICMA), and IGF-2 excess followed by RIA (IE-RIA). Validation of the methods included determination of precision, accuracy, and recovery. The concentration of IGF-1 was measured with all methods, and results were compared among cat groups. RESULTS The intra-assay coefficient of variation was < 10% for AC-RIA, A-ICMA, and AEE-IRMA and 14% to 22% for IE-RIA. The linearity of dilution was close to 1 for each method. Recovery rates ranged from 69% to 119%. Five healthy cats had IGF-1 concentrations > 1,000 ng/mL with the AEE-IRMA, but < 1,000 ng/mL with the other methods. Compared with healthy cats, hyperthyroid cats had significantly higher concentrations of IGF-1 with the A-ICMA method, but lower concentrations with the IE-RIA method. Cats with lymphoma had lower IGF-1 concentrations than did healthy cats regardless of the method used. CONCLUSIONS AND CLINICAL RELEVANCE Differences in the methodologies of assays for IGF-1 may explain, at least in part, the conflicting results previously reported in diabetic cats. Disorders such as hyperthyroidism and lymphoma affected IGF-1 concentrations, making interpretation of results more difficult if these conditions are present in cats with diabetes mellitus.
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Affiliation(s)
- Flurin Tschuor
- Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland
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15
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Ishaq RAR, Soliman SAZ, Foda MY, Fayed MMS. Insulin-like growth factor I: A biologic maturation indicator. Am J Orthod Dentofacial Orthop 2012; 142:654-61. [DOI: 10.1016/j.ajodo.2012.06.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 06/01/2012] [Accepted: 06/01/2012] [Indexed: 10/27/2022]
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16
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Analytical challenges in the detection of peptide hormones for anti-doping purposes. Bioanalysis 2012; 4:1577-90. [DOI: 10.4155/bio.12.128] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although significant progress has been achieved during the past few years with the introduction of new assays and analytical methodologies, the detection and quantification of protein analytes, in particular of peptide hormones, continues to pose analytical challenges for the World Anti-Doping Agency-accredited anti-doping laboratories. In this article, the latest achievements in the application of MS-based methodologies and specific biochemical and immunological assays to detect some of the prohibited substances listed in section S2 of the World Anti-Doping Agency List of Prohibited Substances and Methods are reviewed. In addition, we look towards the future by focusing on some of the most promising analytical approaches under development for the detection of so-called ‘biomarkers of doping’.
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Abstract
Disease activity of acromegaly can be measured in many ways. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) concentrations are the main biochemical markers used to measure the response to treatment. Both GH and IGF1 have been associated with prognosis, in particular mortality. In this review, we discuss the available parameters to assess disease activity in acromegaly.
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Affiliation(s)
- S J C M M Neggers
- Department of Medicine, Section Endocrinology, Erasmus University Medical Center Rotterdam, CA Rotterdam, The Netherlands.
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18
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Varewijck AJ, Janssen JAMJL, Vähätalo M, Hofland LJ, Lamberts SWJ, Yki-Järvinen H. Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases IGF-I bioactivity similarly. Diabetologia 2012; 55:1186-94. [PMID: 22237688 PMCID: PMC3296010 DOI: 10.1007/s00125-011-2435-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Accepted: 12/05/2011] [Indexed: 01/21/2023]
Abstract
AIMS/HYPOTHESIS The aim of this study was to compare IGF-I bioactivity 36 weeks after the addition of insulin glargine (A21Gly,B31Arg,B32Arg human insulin) or NPH insulin to metformin therapy in type 2 diabetic patients who had poor glucose control under metformin monotherapy. METHODS In the Lantus plus Metformin (LANMET) study, 110 poorly controlled insulin-naive type 2 diabetic patients were randomised to receive metformin with either insulin glargine (G+MET) or NPH insulin (NPH+MET). In the present study, IGF-I bioactivity was measured, retrospectively, in 104 out of the 110 initially included LANMET participants before and after 36 weeks of insulin therapy. IGF-I bioactivity was measured using an IGF-I kinase receptor activation assay. RESULTS After 36 weeks of insulin therapy, insulin doses were comparable between the G+MET (68 ± 5.7 U/day) and NPH+MET (71 ± 6.2 U/day) groups (p = 0.68). Before insulin therapy, circulating IGF-I bioactivity was similar between the G+MET (134 ± 9 pmol/l) and NPH+MET (135 ± 10 pmol/l) groups (p = 0.83). After 36 weeks, IGF-I bioactivity had decreased significantly (p = 0.001) and did not differ between the G+MET (116 ± 9 pmol/l) and NPH+MET (117 ± 10 pmol/l) groups (p = 0.91). At baseline and after insulin therapy, total IGF-I concentrations were comparable in both groups (baseline: G+MET 13.3 ± 1.0 vs NPH+MET 13.3 ± 1.0 nmol/l, p = 0.97; and 36 weeks: 13.4 ± 1.0 vs 13.1 ± 0.9 nmol/l, p = 0.71). Total IGF-I concentration did not change during insulin therapy (13.3 ± 0.7 vs 13.3 ± 0.7 nmol/l, baseline vs 36 weeks, p = 0.86). CONCLUSIONS/INTERPRETATION Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases serum IGF-I bioactivity in a similar manner.
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Affiliation(s)
- A. J. Varewijck
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, the Netherlands
| | - J. A. M. J. L. Janssen
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, the Netherlands
| | | | - L. J. Hofland
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, the Netherlands
| | - S. W. J. Lamberts
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, the Netherlands
| | - H. Yki-Järvinen
- Department of Medicine, University of Helsinki, Helsinki, Finland
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Kim WY, Kim MJ, Moon H, Yuan P, Kim JS, Woo JK, Zhang G, Suh YA, Feng L, Behrens C, Van Pelt CS, Kang H, Lee JJ, Hong WK, Wistuba II, Lee HY. Differential impacts of insulin-like growth factor-binding protein-3 (IGFBP-3) in epithelial IGF-induced lung cancer development. Endocrinology 2011; 152:2164-73. [PMID: 21447628 PMCID: PMC3100627 DOI: 10.1210/en.2010-0693] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The IGF axis has been implicated in the risk of various cancers. We previously reported a potential role of tissue-derived IGF in lung tumor formation and progression. However, the role of IGF-binding protein (IGFBP)-3, a major IGFBP, on the activity of tissue-driven IGF in lung cancer development is largely unknown. Here, we show that IGF-I, but not IGF-II, protein levels in non-small-cell lung cancer (NSCLC) were significantly higher than those in normal and hyperplastic bronchial epithelium. We found that IGF-I and IGFBP-3 levels in NSCLC tissue specimens were significantly correlated with phosphorylated IGF-IR (pIGF-IR) expression. We investigated the impact of IGFBP-3 expression on the activity of tissue-driven IGF-I in lung cancer development using mice carrying lung-specific human IGF-I transgene (Tg), a germline-null mutation of IGFBP-3, or both. Compared with wild-type (BP3(+/+)) mice, mice carrying heterozygous (BP3(+/-)) or homozygous (BP3(-/-)) deletion of IGFBP-3 alleles exhibited decreases in circulating IGFBP-3 and IGF-I. Unexpectedly, IGF(Tg) mice with 50% of physiological IGFBP-3 (BP3(+/-); IGF(Tg)) showed higher levels of pIGF-IR/IR and a greater degree of spontaneous or tobacco carcinogen [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone]-induced lung tumor development and progression than did the IGF(Tg) mice with normal (BP3(+/+;) IGF(Tg)) or homozygous deletion of IGFBP-3 (BP3(-/-); IGF(Tg)). These data show that IGF-I is overexpressed in NSCLC, leading to activation of IGF-IR, and that IGFBP-3, depending on its expression level, either inhibits or potentiates IGF-I actions in lung carcinogenesis.
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Affiliation(s)
- Woo-Young Kim
- Department of Thoracic Head, University of Texas M.D. Anderson Cancer Center, TX, USA
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20
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Abstract
Two important biomarkers for the identification of growth hormone or IGF-I administration are IGF-I and P-III-P. These substances are determined in plasma or preferably in serum. There are a number of assays on the market for IGF-I but only two for P-III-P. The principles behind these assays and the choice of assays for doping control purposes are discussed. The future possibility of quantification by mass spectrometry is also briefly discussed.
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Affiliation(s)
- David A Cowan
- Drug Control Centre, Department of Forensic Science and Drug Monitoring, King's College London, London SE1 9NH, United Kingdom.
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21
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Erotokritou-Mulligan I, Bassett EE, Cowan DA, Bartlett C, McHugh C, Sönksen PH, Holt RIG. Influence of ethnicity on IGF-I and procollagen III peptide (P-III-P) in elite athletes and its effect on the ability to detect GH abuse. Clin Endocrinol (Oxf) 2009; 70:161-8. [PMID: 18616716 DOI: 10.1111/j.1365-2265.2008.03319.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
CONTEXT A method based on the two GH dependent markers, IGF-I and procollagen III peptide (P-III-P) has been proposed to detect exogenously administered GH. As previous studies involved predominantly white European elite athletes, it is necessary to validate the method in other ethnic groups. OBJECTIVE To examine serum IGF-I and P-III-P in elite athletes of different ethnicities within 2 h of competing at national or international events. DESIGN Cross-sectional observational study. SETTING National and International sporting events. SUBJECTS 1085 elite athletes of different ethnicities. INTERVENTION Serum IGF-I and P-III-P were measured and GH-2000 discriminant function score was calculated. Effect of ethnicity was assessed. RESULTS In men, IGF-I was 21.7 +/- 2.6% lower in Afro-Caribbeans than white Europeans (P < 0.0001) but there were no differences between other ethnic groups. In women, IGF-I was 14.2 +/- 5.1% lower in Afro-Caribbeans (P = 0.005) and 15.6 +/- 7.0% higher in Orientals (P = 0.02) compared with white Europeans. P-III-P was 15.2 +/- 3.5%, 26.6 +/- 6.6% and 19.3 +/- 5.8% lower in Afro-Caribbean (P < 0.0001), Indo-Asian (P < 0.0001) and Oriental men (P = 0.001), respectively, compared with white European men. In women, P-III-P was 15.7 +/- 4.7% lower in Afro-Caribbeans compared to white Europeans (P =0.0009) but there were no differences between other ethnicities. Despite these differences, most observations were below the upper 99% prediction limits derived from white European athletes. All GH-2000 scores lay below the cut-off limit proposed for doping. CONCLUSIONS The GH-2000 detection method based on IGF-I and P-III-P would be valid in all ethnic groups.
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Affiliation(s)
- Ioulietta Erotokritou-Mulligan
- Endocrinology and Metabolism Unit, Developmental Origins of Health and Disease Division, School of Medicine, University of Southampton, Southampton, UK
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22
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Brugts MP, Ranke MB, Hofland LJ, van der Wansem K, Weber K, Frystyk J, Lamberts SWJ, Janssen JAMJL. Normal values of circulating insulin-like growth factor-I bioactivity in the healthy population: comparison with five widely used IGF-I immunoassays. J Clin Endocrinol Metab 2008; 93:2539-45. [PMID: 18397983 DOI: 10.1210/jc.2007-2454] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND IGF-I immunoassays are primarily used to estimate IGF-I bioactivity. Recently an IGF-I-specific kinase receptor activation assay (KIRA) has been developed as an alternative method. However, no normative values have been established for the IGF-I KIRA. OBJECTIVE The objective of the study was to establish normative values for the IGF-I KIRA in healthy adults. DESIGN This was a cross-sectional study in healthy nonfasting blood donors. STUDY PARTICIPANTS Participants included 426 healthy individuals (310 males, 116 females; age range 18-79 yr). MAIN OUTCOME MEASURES IGF-I bioactivity determined by the KIRA was measured. Results were compared with total IGF-I, measured by five different IGF-I immunoassays. RESULTS Mean (+/- sd) IGF-I bioactivity was 423 (+/- 131) pmol/liter and decreased with age (beta = -3.4 pmol/liter.yr, P < 0.001). In subjects younger than 55 yr, mean IGF-I bioactivity was significantly higher in women than men. Above this age this relationship was inverse, suggesting a drop in IGF-I bioactivity after menopause. This drop was not reflected in total IGF-I levels. IGF-I bioactivity was significantly related to total IGF-I (r(s) varied between 0.46 and 0.52; P < 0.001). CONCLUSIONS We established age-specific normative values for the IGF-I KIRA. We observed a significant drop in IGF-I bioactivity in women between 50 and 60 yr, which was not perceived by IGF-I immunoassays. The IGF-I KIRA, when compared with IGF-I immunoassays, theoretically has the advantage that it measures net effects of IGF-binding proteins on IGF-I receptor activation. However, it has to be proven whether information obtained by the IGF-I KIRA is clinically more relevant than measurements obtained by IGF-I immunoassays.
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Affiliation(s)
- Michael P Brugts
- Department of Internal Medicine, Erasmus MC, Dr. Molewaterplein 50, Rotterdam, The Netherlands.
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23
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Granada ML, Ulied A, Casanueva FF, Pico A, Lucas T, Torres E, Sanmartí A. Serum IGF-I measured by four different immunoassays in patients with adult GH deficiency or acromegaly and in a control population. Clin Endocrinol (Oxf) 2008; 68:942-50. [PMID: 17980002 DOI: 10.1111/j.1365-2265.2007.03120.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND IGF-I is a useful tool in GH disorders diagnosis, however, the use of commercially available kits needs to be validated. OBJECTIVE To validate the use of serum IGF-I concentrations measured by four immunoassays in the diagnosis of adult GH deficiency and acromegaly. DESIGN Cross-sectional study. PATIENTS Fifty GH-deficient (GHD) patients, 41 acromegaly patients and 405 controls. MEASUREMENTS Serum IGF-I concentrations were measured by four commercial immunoassays: (1) RIA-NICHOLS; (2) ICMA-IMMULITE; (3) IRMA-IMMUNOTECH; and (4) non-extraction-IRMA-DSL. Reference values were established from the control population in six age groups. Individual results were transformed to standard deviation score (SD score) from the age-related reference population and reference data provided by each assay manufacturer. Diagnostic sensitivity for GH deficiency was calculated. RESULTS IGF-I measured by the four assays differed significantly. In controls, assay 2 yielded the lowest results, followed by assays 1, 3 and 4 (P < 0.0001 for all comparisons). IGF-I declined with age, but no sex-related differences were observed. When IGF-I was standardized with respect to reference data obtained from the manufacturers, it showed better sensitivity in assays 1 and 2, than with our controls (65%vs. 77.5% and 58%vs. 70%, respectively) for GHD diagnosis. With assays 3 and 4, higher sensitivity was obtained when standardized with our controls (62%vs. 52% and 56%vs. 36%, respectively). In acromegaly, IGF-I was > 2 SD score with all assays. CONCLUSIONS IGF-I SD score for GHD diagnosis differed according to the normative data used. All assays proved to be useful for active acromegaly diagnosis.
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Affiliation(s)
- Maria Luisa Granada
- Department of Clinical Biochemistry, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain.
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Huang Y, Shi R, Zhong X, Wang D, Zhao M, Li Y. Enzyme-linked immunosorbent assays for insulin-like growth factor-I using six-histidine tag fused proteins. Anal Chim Acta 2007; 596:116-23. [PMID: 17616248 DOI: 10.1016/j.aca.2007.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 03/28/2007] [Accepted: 06/04/2007] [Indexed: 11/22/2022]
Abstract
The fusion proteins of insulin-like growth factor-I (IGF-I) and six-histidine tag (IGF-I-6H, 6H-IGF-I-6H) were cloned, expressed, purified and renatured, with their immunoreaction properties and biological activities intact. The binding kinetics between these fusion proteins and anti-IGF-I antibody or anti-6H antibody were studied using surface plasmon resonance (SPR). Two enzyme-linked immunosorbent assay (ELISA) modes, which proved feasible in the measurement of human serum samples, were used to detect IGF-I with the help of the six-histidine tagged proteins. Furthermore, combining the production technique of the six-histidine tagged fusion protein with the competitive sandwich ELISA mode, using an enzyme labeled anti-6H antibody as a tracer, can be a universal immunochemical method to quantitate other polypeptides or proteins.
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Affiliation(s)
- Yong Huang
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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25
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Pokrajac A, Wark G, Ellis AR, Wear J, Wieringa GE, Trainer PJ. Variation in GH and IGF-I assays limits the applicability of international consensus criteria to local practice. Clin Endocrinol (Oxf) 2007; 67:65-70. [PMID: 17437512 DOI: 10.1111/j.1365-2265.2007.02836.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND There is increasing reliance on consensus criteria for decision making. Recent criteria state that acromegaly is excluded by a nadir GH during an oral glucose tolerance test (OGTT) of < 1 microg/l and a normal level of IGF-I. OBJECTIVE To study GH and IGF-I assay performance close to cut-off values for active acromegaly. DESIGN AND METHODS Two serum samples known to give borderline results were sent to all centres participating in the UK National External Quality Assessment Service (NEQAS). Sample A was assigned to be a nadir during an OGTT and sent for GH assessment to 104 centres. Sample B, with a clinical scenario, was sent to 23 centres that measure IGF-I, and these centres were asked to measure IGF-I, interpret the result and provide the source of their reference ranges (RRs). RESULTS For sample A, the median GH was 2.6 mU/l (range 1.04-3.5 mU/l). Applying a conversion factor (CF) of 2.0 (1 microg/l = 2 mU/l), the most negatively biased method classified 10% of the values consistent with acromegaly, while the most positively biased method classified all values as consistent with the diagnosis. Applying a CF of 3.0 (1 microg/l = 3 mU/l), only 11% of results were consistent with acromegaly. For sample B, the median IGF-I was 50.8 nmol/l (range 24.3-60.9 nmol/l). All centres used age-related RRs. There was a 50% variation in the upper limit of the RRs between centres. Overall, 30% of the IGF-I results were against the diagnosis. There was little agreement in the RRs quoted by centres using the same method. CONCLUSION Variability in assay performance, coupled with use of inappropriate CFs and RRs, undermines the applicability of international consensus criteria to local practice.
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Affiliation(s)
- A Pokrajac
- Christie Hospital NHS Trust, Department of Endocrinology, Manchester, UK
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26
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Hovind P, Lamberts S, Hop W, Deinum J, Tarnow L, Parving HH, Janssen JAMJL. An IGF-I gene polymorphism modifies the risk of developing persistent microalbuminuria in type 1 diabetes. Eur J Endocrinol 2007; 156:83-90. [PMID: 17218729 DOI: 10.1530/eje.1.02308] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Derangements of the GH-IGF-I axis have been associated with microalbuminuria (MA) in type 1 diabetes. The aim of this study was to investigate whether an IGF-I gene promoter polymorphism influenced the development of persistent MA in type 1 diabetes. DESIGN A prospective follow-up study of a cohort of 277 patients with newly diagnosed type 1 diabetes consecutively enrolled between September 1979 and August 1984. METHODS Urinary albumin excretion rate over 24 h was measured in each patient at least once a year. Persistent MA was defined as a urinary albumin excretion rate between 30 and 300 mg/24 h. RESULTS During a median follow-up of 18.0 years (range 1.0-21.5), 79 of 277 patients developed persistent MA. IGF-I gene genotype was available for 216 subjects; in 73% of the subjects, the wild-type genotype of this IGF-I gene polymorphism was present, while 27% had the variant type. At baseline, there were no differences in IGF-I levels and HbA(1c) values between subjects with the wild type and subjects with variant type. By Kaplan-Meier analysis, subjects with the variant type of this polymorphism had during follow-up a higher risk of development of MA compared subjects with the wild type (P = 0.03). CONCLUSIONS Subjects with the variant type of an IGF-I gene polymorphism had a significantly increased risk of developing MA. This risk was not mediated through changes in circulating IGF-I levels. Our study suggests that in type 1 diabetes, this IGF-I gene polymorphism is a risk factor of MA.
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Abstract
The diagnosis of disorders of growth hormone (GH) is dependent upon accurate measurement of insulin-like growth factor-I (IGF-I) concentrations since serum IGF-I assays have been found to be useful as a screening tests for the presence of growth hormone deficiency (GHD) in children and in both children and adults they have been found very useful in establishing the diagnosis of acromegaly. IGF-I is also used extensively to monitor the response to GH treatment in children and adults and to monitor the response to treatment in acromegaly. Since IGF-I is influenced by several other hormones and physiologic factors as well as GH, a knowledge of its regulation is essential to understanding how to properly interpret the measurements. Several technical criteria are required for successful laboratory estimation of IGF-I values. These include elimination of interference of IGF-I-binding proteins (IGFBP), utilization of adequate numbers of normal subjects to define the normal ranges and importantly the use of high affinity, high specificity antisera that allow precise and reproducible measurements of the biologically active peptide. Cross comparisons of various commercial assays show that the results generally are similar when values are in the normal range. However, the assays have different performance characteristics when concentrations are either above or below the normal range. To obtain cross laboratory standardization for values outside the normal range requires utilization of similar, high-quality reagents and techniques that are reasonably comparable. Without this degree of standardization, cross comparisons among various reference laboratories are likely to continue to show wide divergence for values that are above or below the 95% confidence interval. A future goal should be the development of standard procedures and reagents that eliminate this degree of variability.
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Affiliation(s)
- David R Clemmons
- CB# 7170, 8024 Burnett-Womack, Division of Endocrinology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7170, USA.
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Littlejohn EE, Weiss RE, Deplewski D, Edidin DV, Rosenfield R. Intractable early childhood obesity as the initial sign of insulin resistant hyperinsulinism and precursor of polycystic ovary syndrome. J Pediatr Endocrinol Metab 2007; 20:41-51. [PMID: 17315528 DOI: 10.1515/jpem.2007.20.1.41] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE We report that intractable early childhood obesity may be associated with severe insulin resistance syndromes (pseudo-Cushing's syndrome and pseudo-acromegaly) and precede polycystic ovary syndrome (PCOS). STUDY DESIGN/RESULTS Patient 1 had prepubertal obesity followed by early puberty and was diagnosed with pseudo-Cushing's syndrome and insulin resistance at 10.3 years. Oligomenorrhea, androgen excess, and type 2 diabetes mellitus (DM2) emerged at 13.5 years. Patient 2 developed intractable prepubertal obesity followed by atypical true sexual precocity and pseudo-Cushing's syndrome in early childhood. By 11.3 years, oligomenorrhea, androgen excess, and DM2 had appeared. Patient 3 had prepubertal overgrowth in weight and height and was diagnosed with pseudo-acromegaly, menstrual irregularity, androgen excess, and impaired glucose tolerance at 14.3 years of age. Patient 4 had prepubertal overgrowth that evolved into pseudo-acromegaly, insulin resistance, secondary amenorrhea, and androgen excess at 15.6 years. CONCLUSIONS Intractable prepubertal obesity was recognized to culminate in early childhood pseudo-Cushing's syndrome or pseudo-acromegaly, which are manifestations of insulin-resistant hyperinsulinism, and to herald adolescent PCOS.
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Affiliation(s)
- Elizabeth E Littlejohn
- University of Chicago, Pritzker School of Medicine, Department of Pediatrics, Section of Pediatric Endocrinology, 5841 S. Maryland Avenue, IL 60637, USA.
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Anckaert E, Schiettecatte J, Vanbesien J, Smitz J, Velkeniers B, De Schepper J. Variability among five different commercial IGF-1 immunoassays in conditions of childhood-onset GH deficiency and GH therapy. Acta Clin Belg 2006; 61:335-9. [PMID: 17323843 DOI: 10.1179/acb.2006.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
IGF-1 measurement is used for screening of GH deficiency and monitoring of GH therapy in children. However, several commercial immunoassays are currently used and reference values provided by manufacturers are very different. The aim of this study was to compare commercial IGF-1 assays 1) in terms of absolute values and 2) in terms of clinical interpretation of results based on IGF-1 reference values in serum samples from children with GH therapy, with untreated GH deficiency and with obesity. Serum samples of 9 patients were sent frozen to 5 university hospitals using 5 different IGF-1 assays. The inter-laboratory coefficient of variation (CV) was calculated for the 9 samples. For clinical interpretation, results were expressed as SD scores based on reference values provided by manufacturers (and used in these laboratories). The mean inter-laboratory CV (range) for the 9 serum samples was 25.8% (16.7-35.9%). Major variability was noted in the SD-scores between IGF-1 assays for 3 tested serum samples from GH-treated patients with a difference between the lowest and highest SD score of 2.6 up to 3.2. In conclusion, there is a large variability among commercial IGF-1 immunoassays, not only in terms of absolute values, but also in terms of clinical interpretation in pediatric serum samples. There is a need for IGF-1 immunoassay harmonization and for the establishment of adequate reference values.
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Affiliation(s)
- E Anckaert
- Laboratorium Radioimmunologie, Academisch Ziekenhuis Vrije Universiteit Brussel, Brussels, Belgium.
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30
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Shi R, Huang Y, Wang D, Zhao M, Li Y. Expression and characterization of insulin growth factor-I-enhanced green fluorescent protein fused protein as a tracer for immunoassay. Anal Chim Acta 2006; 578:131-6. [PMID: 17723704 DOI: 10.1016/j.aca.2006.06.071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2006] [Revised: 06/27/2006] [Accepted: 06/27/2006] [Indexed: 11/16/2022]
Abstract
The insulin-like growth factor-I (IGF-I) is an important polypeptide hormone under investigation for body metabolism study and for doping detection. Here, we describe for the first time the expression of a recombinant fusion protein of IGF-I and the enhanced green fluorescent protein (EGFP). The genetic fusion approach enables preparation of conjugates with 1:1 stoichiometry and homogeneous structure. The fused protein (EGFP-IGF-I) was expressed as a soluble protein in cytoplasm of Escherichia coli and its fluorescence and immunoreaction properties were thoroughly characterized. Finally, we demonstrated the utility of the EGFP-IGF-I fusion protein for the fluorescence immunoassay of IGF-1. The linear range of the assay is 1.6 x 10(-8) to 2.0 x 10(-6) M with a detection limit of 1.6 x 10(-8) M. To our knowledge, this is the first time that EGFP has been used as a quantitative label in a fusion protein to develop a quantitative assay for IGF-I. Furthermore, the use of genetically engineered fusion proteins, which combine peptide hormones with fluorescent protein, can lead to a new labeling approach to a number of bioanalytical applications.
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Affiliation(s)
- Ruina Shi
- College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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31
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Derr RL, Cameron SJ, Golden SH. Pre-Analytic Considerations for the Proper Assessment of Hormones of the Hypothalamic-Pituitary Axis in Epidemiological Research. Eur J Epidemiol 2006; 21:217-26. [PMID: 16547837 DOI: 10.1007/s10654-006-0011-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2006] [Indexed: 11/24/2022]
Abstract
There is growing epidemiological interest in hormones as predictors of chronic diseases. The correct handling and analysis of hormones can be cumbersome, and great care must be taken in these processes in order to gain the most information possible. Given differences in sampling, processing, and stability of the various hormonal assays, we sought to provide a comprehensive review to aid future epidemiological research. We have coupled a thorough literature search with our own analytical experience to outline common laboratory problems one must consider in analyzing the hormones of the hypothalamic-pituitary axis. In addition, we describe the benefits and limitations of using alternative media--including urine, saliva, and blood spots on filter paper--to measure endocrine hormones in epidemiological studies.
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Affiliation(s)
- Rachel L Derr
- Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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32
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Feinberg EC, Molitch ME, Endres LK, Peaceman AM. The incidence of Sheehan's syndrome after obstetric hemorrhage. Fertil Steril 2006; 84:975-9. [PMID: 16213852 DOI: 10.1016/j.fertnstert.2005.04.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2005] [Revised: 04/15/2005] [Accepted: 04/15/2005] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To estimate the incidence of Sheehan's syndrome in a well-described cohort of patients with obstetric hemorrhage. DESIGN Retrospective cohort study. SETTING Tertiary care center. PATIENT(S) Two hundred patients. INTERVENTION(S) Questionnaires were sent to study and comparison patients asking about menstrual dysfunction, lactation difficulty, cold intolerance, fatigue, axillary and pubic hair loss, and secondary infertility. MAIN OUTCOME MEASURE(S) Women who experienced two or more symptoms were referred for hormone testing of insulin-like growth factor 1 (IGF-1), T4, PRL, and early morning cortisol (F) levels. RESULT(S) A total of 109 patients responded to the survey, a 55% response rate. Fourteen of 55 (25%) patients in the hemorrhage group identified themselves as suffering from two or more symptoms on the questionnaire. Eight of the 14 patients were tested, but none had hormonal evidence of hypopituitarism. Four of 54 (7%) comparison patients also identified themselves as suffering from two or more symptoms, but neither of the two tested had hormonal evidence of hypopituitarism. CONCLUSION(S) Among women with postpartum hemorrhage, subsequent development of clinical symptoms does not correlate well with laboratory evidence of hypopituitarism. Clinically significant Sheehan syndrome is an uncommon consequence of obstetric hemorrhage in today's environment.
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Affiliation(s)
- Eve C Feinberg
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, Illinois, USA.
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33
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Abstract
Biochemical assessment of growth hormone (GH) status is required in both suspected GH deficiency and GH excess. GH secretion can either be measured through investigation of the pituitary or by monitoring markers that change as a consequence of GH action on its target tissues. The two most widely used and, to date, best validated biochemical parameters are immunoassay measurement of either human GH (hGH) or insulin-like growth factor (IGF)-I. The fundamental difference between measurement of hGH and IGF-I is that the first reflects GH secretion while the second reflects GH action. However, because GH secretion is pulsatile in nature, random blood sampling for determination of hGH levels is only minimally informative. Analytical methods for measuring GH and IGF-I show considerable between-method variability. Since these parameters are used in establishing diagnoses and in monitoring GH-related diseases, the endocrinologist should be aware of the specifications and limitations of the analytical methods available.
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Pokrajac-Simeunovic A, Trainer PJ. Pitfalls in the diagnosis of acromegaly. HORMONE RESEARCH 2005; 62 Suppl 3:74-8. [PMID: 15539804 DOI: 10.1159/000080504] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acromegaly is a disfiguring and disabling illness which, when inadequately treated, reduces life expectancy. An implication of the ability to offer effective treatment is the increased onus on physicians of all sorts to ensure acromegaly is diagnosed and treated as early as possible. To this end, criteria for the diagnosis of acromegaly have been proposed in the consensus statement of Giustina et al. However, other data suggest that the proposed criteria are not rigorous enough and strict adherence to the guidelines would result in failure to diagnose a significant number of patients. A review of published experience suggests that the combination of a GH nadir during an oral glucose tolerance test of <0.25 microg/l plus a normal age-related insulin growth factor-I level makes the diagnosis of acromegaly extremely unlikely.
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Paisley AN, Trainer PJ. The Challenges of Reliance on Insulin-Like Growth Factor I in Monitoring Disease Activity in Patients with Acromegaly. Horm Res Paediatr 2005; 62 Suppl 1:83-8. [PMID: 15761238 DOI: 10.1159/000080764] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Serum insulin-like growth factor I (IGF-I) is an important marker of disease activity in patients with acromegaly, and epidemiological data indicate control of circulating IGF-I in patients with acromegaly restores life expectancy to normal. Improvements in the quality of, and access to, IGF-I assays has encouraged monitoring of acromegaly with IGF-I, although circulating growth hormone (GH) and IGF-I values provide different information, so ideally both should be monitored. However, the introduction of the GH receptor antagonist pegvisomant poses new challenges. Pegvisomant binds with high affinity to GH receptors, thereby blocking the action of GH at the tissue level and rendering the hormone biologically inactive. This leaves IGF-I as the principal marker of disease activity. It is conceptually possible to induce a state of functional GH deficiency (GHD) with pegvisomant with IGF-I values within the normal range. With the goal of minimizing the risk of over-treatment and GHD, we have provided preliminary guidance on the target range for IGF-I in patients receiving pegvisomant based on the gender- and decade-based percentile ranges for IGF-I of adult patients with untreated GHD enrolled in the Pfizer International Metabolic Database (KIMS).
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Nelson RW, Nedelkov D, Tubbs KA, Kiernan UA. Quantitative Mass Spectrometric Immunoassay of Insulin Like Growth Factor 1. J Proteome Res 2004; 3:851-5. [PMID: 15359740 DOI: 10.1021/pr0499388] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reported in this work are the development of mass spectrometric immunoassay (MSIA) devices and methods for the qualitative analysis of IGF-1 and -2, and the rigorous quantification of IGF-1 from human plasma. A method involving addition of SDS in moderate concentration to unfractionated plasma for disrupting IGF/IGFBP complexes was initially developed. The method is suitable for the direct extraction of the IGFs and subsequent mass spectrometric analysis. Rat plasma, containing IGF-1 that is mass shifted from human IGF-1, was used as an internal reference standard (IRS) for the quantification of IGF-1 directly from human plasma. A standard curve with linear dynamic range of at least 2 orders of magnitude was constructed from serially diluted IGF-1 standards containing equal amounts of rat plasma. Using the standard curve, IGF-1 levels in plasma samples from eight individuals were determined. The limit of detection for the IGF-1 MSIA was also evaluated and established to be approximately 15 pM. The assay is rapid and can be performed in parallel via high-throughput robotics processing. Furthermore, the mass spectrometry aspect of the developed IGF-1 immunoassay offers a new dimension in the ongoing study of IGF-1 and related diseases.
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37
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Pandian R, Nakamoto JM. Rational use of the laboratory for childhood and adult growth hormone deficiency. Clin Lab Med 2004; 24:141-74. [PMID: 15157561 DOI: 10.1016/j.cll.2004.01.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
No laboratory test has sufficient diagnostic sensitivity and specificity to serve as a gold standard for the diagnosis for GHD: therefore, test results must be interpreted after assessment of risk for GHD is determined on clinical grounds. Growth data are particularly crucial for diagnosis of childhood GHD;history of known pituitary damage and presence or absence of other pituitary hormone deficiencies are the critical elements for the diagnosis of adult GHD. New reference preparations are available for GH and IGF-I and should greatly aid interassay comparisons when the preparations are universally adopted.GH stimulation testing remains a key part of the diagnosis of adult GHD, but is currently being de-emphasized for the diagnosis of pediatric GHD. Better interassay comparative data and organized clinical collaboration between clinicians and test manufacturers/laboratories to set rational clinical diagnostic cutoffs would improve greatly the clinical usefulness of GH stimulation testing. The availability of statistically sound age- and sex-related normative data for IGF-I and IGFBP3 make these key tests for the diagnosis of childhood GHD. Although IGF-I may not be a perfect test for the diagnosis of adult GHD, it may be sufficiently informative in many cases to warrant using it ona routine basis. IGF-I also has a role in monitoring the safety of adult patients who are on GH treatment; studies are underway to determine if IGF-I may be useful in the future for optimization of GH dosaging.
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Affiliation(s)
- Raj Pandian
- Quest Diagnostics Nichols Institute, San Juan Capistrano, CA 92690, USA.
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38
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Meinhardt U, Eblé A, Besson A, Strasburger CJ, Sraer JD, Mullis PE. Regulation of growth-hormone-receptor gene expression by growth hormone and pegvisomant in human mesangial cells. Kidney Int 2003; 64:421-30. [PMID: 12846737 DOI: 10.1046/j.1523-1755.2003.00117.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Mice transgenic for growth hormone develop mesangial proliferation, glomerular hypertrophy, and progressive glomerular sclerosis suggesting that the growth hormone-insulin-like growth factor I (IGF-I) pathway plays an important role. Therefore, we studied the impact of variable concentrations of 22 kD, 20 kD growth hormone, as well as of the growth hormone receptor antagonist pegvisomant (B2036-PEG), on both the growth hormone receptor (GHR/GHBP) gene expression and growth hormone binding protein (GHBP) formation in a human glomerular mesangial cell line. Further, the impact on collagen, IGF-I and IGF binding protein-1 (IGFBP-1) formation was studied. METHODS In order to assess transcription, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used. RESULTS Physiologic doses of 22 kD or 20 kD growth hormone caused a dose-dependent and significant (P < 0.01) up-regulation of GHR/GHBP gene transcription, whereas supraphysiologic doses (50 and 500 ng/mL) resulted in down-regulation (P < 0.001). Whenever pegvisomant was used, there was no increase in GHR/GHBP expression. These data were confirmed using run-on experiments. Further, the assessment of GHBP presented a constant, dose-dependent increase, which was completely abolished in the experiments where pegvisomant was used. CONCLUSION We present data showing that growth hormone has a direct impact on GHR/GHPB gene transcription and that pegvisomant is a potent growth hormone receptor antagonist in human mesangial cells. In addition, although the GHR/GHBP gene transcription is down-regulated by supraphysiologic growth hormone concentrations, this effect was not found when GHBP levels were measured. This finding may reflect a self-inhibitory effect of growth hormone on the level of GHR/GHBP gene transcription, which does not involve the regulation of the shedding of GHBP and may, therefore, be of physiologic interest.
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Affiliation(s)
- Udo Meinhardt
- Paediatric Endocrinology, University Children's Hospital, Inselspital, Bern, Switzerland
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Janssen JAMJL, van der Lely AJ, Lamberts SWJ. Circulating free insulin-like growth-factor-I (IGF-I) levels should also be measured to estimate the IGF-I bioactivity. J Endocrinol Invest 2003; 26:588-94. [PMID: 12952376 DOI: 10.1007/bf03345225] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Free IGF-I by analogy with sex and adrenal steroids and thyroid hormones, may be the major biologically active hormonal form of IGF-I. Because of methodological difficulties in measuring the free IGF-I the measurement of total IGF-I in blood is often used to assess the activity of the endocrine GH-IGF-I axis in clinical studies. However, there is currently no reliable standard reference method for circulating total IGF-I against which individual samples can be calibrated. In addition, in many of the common methods used to measure circulating total IGF-I levels, remaining insulin-like growth factor, binding proteins (IGFBPs) or binding protein fragments after sample extraction, may still interfere and produce falsely increased or decreased circulating total IGF-I levels. This latter phenomenon occurs especially under pathologic conditions. In addition, it has also been suggested that altered post-sampling integrity of IGF-I in vitro might contribute to the reported inconsistencies in circulating total IGF-I levels in literature. Although at the moment there is also no "golden standard" for the measurement of circulating free IGF-I levels, we discuss some studies in this paper that in our opinion, have demonstrated conclusively that circulating free IGF-I levels in several conditions reflect the IGF-I bioactivity better than circulating total IGF-I levels. Therefore, when evaluating the IGF-I bioactivity in health and disease, we recommend measuring also circulating free IGF-I.
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Affiliation(s)
- J A M J L Janssen
- Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands.
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40
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Gruden G, Araf S, Zonca S, Burt D, Thomas S, Gnudi L, Viberti G. IGF-I induces vascular endothelial growth factor in human mesangial cells via a Src-dependent mechanism. Kidney Int 2003; 63:1249-55. [PMID: 12631341 DOI: 10.1046/j.1523-1755.2003.00857.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Both insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) have been implicated in the pathogenesis of early renal dysfunction in diabetes. We investigated whether IGF-I affects VEGF gene expression and protein secretion in human mesangial cells. Furthermore, we studied the intracellular signaling pathway involved and the interaction of IGF-I with mechanical stretch, a known VEGF inducer. METHODS Human mesangial cells were exposed to IGF-I in the presence and in the absence of (1) anti-IGF-I type I receptor antibody (alpha IR3) (1 microg/mL), a monoclonal antibody blocking the IGF-I type I receptor; (2) wortmannin (600 nmol/L), a phosphatidylinositol 3-kinase (PI3K) inhibitor; (3) 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), a specific Src inhibitor (10 micromol/L); and (4) cyclic stretch (approximately 10% elongation). RESULTS IGF-I induced a dose-dependent increase in VEGF protein levels (10(-11) mol/L, 5%; 10(-10) mol/L, 14%; 10(-9) mol/L, 46%; 10(-8) mol/L, 66%; 10(-7) mol/L, 68%; P < 0.001). IGF-I-induced VEGF production rose by 6 hours with a peak at 12 hours, and declined by 24 hours (52%, 72%, and 34%, respectively; P < 0.01 at 12 hours). A corresponding 50% increase in VEGF mRNA levels was seen at 6 hours (P < 0.01). IGF-I-induced VEGF protein secretion was not affected by the addition of wortmannin (IGF-I, 76% vs. IGF-I + wortmannin, 79% increase over control; P = NS), but was abolished by alpha IR3 (IGF-I, 69% vs. IGF-I +alpha IR3, 0%; P < 0.001) and significantly reduced by PP2 (IGF-I, 50% vs. IGF-I + PP2, 14%; P < 0.01). Simultaneous exposure of human mesangial cells to both IGF-I and stretch failed to further increase VEGF production (IGF-I, 1.49 +/- 0.05; stretch, 1.76 +/- 0.05; and IGF-I + stretch, 1.83 +/- 0.11). CONCLUSION IGF-I induces VEGF gene expression and protein secretion in human mesangial cells via a Src-dependent mechanism.
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Affiliation(s)
- Gabriella Gruden
- Department of Diabetes and Endocrinology, GKT School of Medicine, King's College London, London, England, United Kingdom.
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