Description:ProductNameInsulinGrowthFactor-1.CategoryGrowthFactors.SampleTypeSerum.Sensitivity4,9ng/mL.DescriptionEnzymelinkedimmunosorbentassayforthedeterminationofInsulinlikeGrowthFactor-1inhumanserum.#ofSamples1X96Assays.IntendedUseImmunoenzymetricassayfortheinvitroquantitativemeasurementofhumanInsulin-likeGrowthFactor-I(IGF-I)inserum.BackgroundA.BIOLOGicalactivitiesInsulin-likegrowthfactorI(IGF-I)orSomatomedin-C(SM-C)isabasic70aminoacidsinglechainpolypeptide(MW:7649Da)similartoproinsulin(50%sequencehomology),andtotheotherwell-characterizedmemberofthesomatomedinfamily:IGFII(67AA,70%sequencehomologywithIGF-I).IGF-Iisthemostimportantfactor,whichmediatesthegrowthpromotingactionsofgrowthhormone,apituitaryhormonewithhighlyfluctuatingbloodlevelsduetopulsatilerelease.ThebloodconcentrationofIGF-Iismorestableduetothebindingtocarrierproteins.Theconcentrationofthepredominantbindingprotein(MW53000)aswellastheproductionofIGF-I,areregulatedbygrowthhormone.IGF-Iisproducedbytheliver,andothertissues,andithasendocrine,paracrineandautocrineactivities.Itstimulatesgrowthandregulatesdifferentiationofvarioustissues,displaysinsulin-likeactivitiesandpromotescartilagegrowth.AlthoughGHisthemostimportantfactorcontrollingIGF-Isecretionandconcentration,otherfactorsarealsodeterminant:theage(withapeakatadolescence),thesex,thenutritionalstatus,andotherhormones(oestrogen,thyroxin,prolactin,..).SpecifictrophicstimulimainlycontrolIGF-Isecretioninthelocalmicroenvironmentofaparticularorgan(paracrineactivities),whilebloodIGF-Iconcentrationisthemostimportantvariableforbalancedsystemicgrowth(endocrineactivities).B.Clinicalapplications•Growthretardation:Growthretardationmaybeduetoseveralcauses,amongwhichdeficientGHproduction(hypopituitarism),whichisassociatedwithlowIGF-Ibloodlevels.BecauseofthedifficultiestogetinterpretableresultsfromGHmeasurements(bydynamicmultipleorstimulationtests),thedeterminationofthestableIGF-Iconcentrationinplasmaisoftenconsideredasasimplescreeningtesttoevaluation"GHimpregnation"ofthepatientbeforedecidingmoreextensiveinvestigations.Inseveralclinicalsituationswithimpairedgrowth,lowIGF-IlevelsmaybeobserveddespitenormalorhighGHproduction(i.e.malnutrition,chronicdiseasesstates,somegeneticdwarfslikePygmies,..).Interestingly,childrenwithdiscreteGHneuro-secreterydysfunctionmaydisplaylowIGF-IvaluesdespitenormalGHlevelsbyconventionaltesting.TheresultsofIGF-IassaymustbeinterpretedcautiouslybyconsideringthenormalvariationsofIGF-Iduringchildhoodandadolescence(seeRosenfeldetal).•Acromegaly:IGF-Ilevelsareelevatedinacromegaly(excessproductionofGH)andmayserveasanindicatorofdiseaseseverity.ResultsaremorereADIlyinterpretedbecausethenormalvaluesaremoreeasilydefinedinadults.IGF-Imeasurementsarealsousefultomonitortreatment.•Research:TheIGF-IEASIAkitisaninvaluabletooltostudythemodificationsofthisgrowthfactorduringphysiologic(i.e.pregnancy)orpathologic(i.e.diabetes)situations,andthelocalregulationofIGF-Iproductioninrelationtoitsparacrineandautocrineactivities(woundhealing,organregeneration,neoplasticgrowth,foetaldevelopment,gonadalregulation,etc).PrinciplesofthemethodTheIGF1-EASIAisasolidphaseEnzymeAmplifiedSensitivityImmunoassayperformedonbreakablemicrotiterplates.Inthepresentkit,hasintroducedapre-treatmentstepinordertoimprovetheclinicalperformanceoftheassay.ItiswellestablishedthatthebindingproteinsinterferewiththeEASIAassayforIGF1.Thepre-treatmentstepusedbyistheacid-ethanolprocedureofDaughadayetal.(8)AfixedamountofIGF1-labelledwithhorseradishperoxidase(HRP),competewithunlabelledIGF1presentinthecalibrators,controlsandsamplesforalimitednumberofbindingsitesonaspecificantibody.After1hourincubationatroomtemperature,themicrotiterplateiswashedtostopthecompetitionreaction.TheChromogenicsolution(TMB)isaddedandincubatedfor30min.ThereactionisstoppedwiththeadditionofStopSolutionandthemicrotiterplateisthenreadattheappropriatewavelength.Theamountofsubstrateturnoverisdeterminedcolourimetricallybymeasuringtheabsorbance,whichisinverselyproportionaltotheIGF1concentration.AcalibrationcurveisplottedandIGF1concentrationinsamplesisdeterminedbyinterpolationfromthecalibrationcurve.StorageandStABIlity•Beforeopeningorreconstitution,allkitcomponentsarestableuntiltheexpirydate,indicatedontheviallabel,ifkeptat2to8°C.•Unusedstripsmustbestored,at2°C-8°C,inasealedbagcontainingadesiccantuntilexpirationdate.Afterreconstitution,calibratorsandcontrolsarestableforoneweekat2to8°C.Forlongerstorageperiods,aliquotsshouldbemadeandkeptat-20°Cformaximum3months.AvoidsuccessivefreezingandthawingTheconcentratedWashSolutionisstableatroomtemperatureuntilexpirationdate.•FreshlypreparedWorkingWashsolutionshouldbeusedonthesameday.TheWorkingIGF1-HRPconjugateisstablefor4hoursatroomtemperature,avoiddirectsunlight.Alterationsinphysicalappearanceofkitreagentsmayindicateinstabilityordeterioration.ProductNameInsulinGrowthFactor-1.CitationZhongD,XiongL,LiuT,LiuX,LiuX,ChenJ,SunSY,KhuriFR,ZongY,ZhouQ,ZhouW.Theglycolyticinhibitor2-deoxyglucoseactivatesmultipleprosurvivalpathwaysthroughIGF1R.JBiolChem.2009Aug28;284(35):23225-33.Epub2009Jul1.PubMedPMID:19574224;PubMedCentralPMCID:PMC2749096.ExperimentNameActivefreeIGF-1ELISA.ExperimentBackground1.Dianshenget.al.discoveredthat2-DGtreatmentsdisruptedthebindingbetweeninsulin-likegrowthfactor1(IGF-1)andIGF-bindingprotein3(IGFBP3)sothatthefreeformofIGF-1couldbereleasedfromtheIGF-1.IGFBP3complextoactivateIGF-1receptor(IGF1R)signaling.2.2-deoxyglucose(2-DG)iswellcharacterizedasaglycolyticinhibitor.ExperimentSteps1.Incubate100pgoffreeIGF-1with20ngofIGFBP3ina10-ulvolumeat4°CovernighttoformtheIGF-1.IGFBP3complex.2.Treatthiscomplextovariousconcentrationsof2-DGfor15minatroomtemperature.3.DeterminetheactivefreeIGF-1ELISAkitusingaprotocolprovidedbythemanufacturer.FunctionTheinsulin-likegrowthfactors,isolatedfromplasma,arestructurallyandfunctionallyrelatedtoinsulinbuthaveamuchhighergrowth-promotingactivity.SubcellularLocationSecreted.SimilarityBelongstotheinsulinfamily.AdditionalInformation:NameInsulinGrowthFactor-1ELISAKitRelatedProductNamesInsulinGrowthFactor-1ELISAKit;IGF-I;SomatomedinIgf-1InsulinGrowthFactor-1IGF-1MolecularWeight17093SwissProtNumberP05017IntendedUseResearchUseOnly