Untersuchungen zur idiopathischen Hypertriglyceridämie des Zwergschnautzers in Nordamerika [Elektronische Ressource] = Investigations into idiopathic hypertriglyceridemia in the miniature schnauzer in North America / von Panagiotis G. Xenoulis

Panagiotis Xenoulis

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2008
• Nombre de lectures: 62
• Langue: Deutsch

Extrait

Ausdem
GastrointestinalLaboratory
DepartmentofSmallAnimalClinicalSciences
CollegeofVeterinaryMedicineandBiomedicalSciences
TexasA&MUniversity,CollegeStation,Texas,USA
Vorstand:SandeeHartsfield,DVM,MS,Dipl.ACVA

AngefertigtunterderLeitungvon
JörgM.Steiner,Dr.med.vet.,PhD,Dipl.ACVIM,Dipl.ECVIM,CA

Vorgelegtüber
Prof.Dr.med.vet.Dr.med.vet.habil.JohannesHirschberger
MedizinischeKleintierklinikderTierärztlichenFakultät
Ludwig,Maximilians,UniversitätMünchen
Vorstand:Prof.Dr.med.vet.Dr.med.vet.habil.KatrinHartmann


Untersuchungen zur idiopathischen Hypertriglyceridämie
des Zwergschnauzers in Nordamerika


Investigations into idiopathic hypertriglyceridemia in the
Miniature Schnauzer in North America


Inaugural,Dissertation
zurErlangungdertiermedizinischenDoktorwürde
derTierärztlichenFakultätder
Ludwig,Maximilians,UniversitätMünchen

von
PanagiotisG.Xenoulis
aus
Athens,Greece

München2008



GedrucktmitGenehmigungderTierärztlichenFakultät
derLudwig,Maximilians,UniversitätMünchen





Dekan:Univ.,Prof.Dr.Braun
Berichterstatter:Univ.,Prof.Dr.Hirschberger
Korreferent/en:Univ.,Prof.Dr.Stangassinger




TagderPromotion:18.Juli2008







Thisthesisisdedicatedto
MyparentsGiorgosandAndromachi,mysisterMaria,andPatricia Listofabbreviations
List of abbreviations


°C degreesCelsius
95%CI 95%confidenceinterval
=g microgram
ACTH adenocorticotropichormone
ALP alkalinephosphatase
ALT alanineaminotransferase
AST aspartateaminotransferase
CETP cholesterylestertransferprotein
dL deciliter
EDTA ethylenediaminetetraaceticacid
GGT gamma,glutamyltransferase
HDL highdensitylipoprotein
IDL intermediatedensitylipoprotein
L liter
LCAT lecithincholesterolacyltransferase
LDL lowdensitylipoprotein
LPL lipoproteinlipase
mg milligram
min minutes
mL milliliter
NAFLD nonalcoholicfattyliverdisease
NEFA nonesterifiedfattyacid
p pvalue
PLN proteinloosingnephropathy
rpm revolutionsperminute
VLDL verylowdensitylipoprotein
xg centrifugalforce,expressedasxgravity

ITableofcontents
Table of contents

I Introduction 1

II Literature review 3
1. Lipids 3
2. Lipoproteins 4
3. Apolipoproteins 6
3.1. ApolipoproteinC,II 8
4. Plasmalipidenzymes 8
4.1. Lipoproteinlipase 8
4.2. Hepatictriglyceridelipase 9
4.3. Lecithincholesterolacyltransferase(LCAT) 10
4.4. Cholesterylestertransferprotein(CETP) 10
5. Lipidmetabolism 10
5.1. Exogenouspathway 11
5.2. Endogenouspathway 12
6. Disordersoflipidmetabolism 14
6.1. Definitions 14
6.2. Laboratoryevaluationoflipiddisorders 15
6.2.1. Serumturbidity 15
6.2.2. Refrigerationtest 17
6.2.3. Methodsforquantificationandcharacterizationoflipidsinblood 19
6.3. Causesofhyperlipidemiaindogs 19
6.3.1. Secondarycausesofhyperlipidemiaindogs 19
6.3.1.1. Endocrinediseases 19
6.3.1.2. Pancreatitis 20
6.3.1.3. Obesity 21
6.3.1.4. Proteinlosingnephropathy(PLN) 21
6.3.1.5. Cholestasis 22
6.3.1.6. Othercauses 22
6.3.2. Primarycausesofhyperlipidemiaindogs 23
IITableofcontents
6.4. Clinicalsignsandcomplicationsofhyperlipidemia 24
6.4.1. Pancreatitis 24
6.4.2. Atherosclerosis 26
6.4.3. Insulinresistanceanddiabetesmellitus 27
6.4.4. Liverdisease 28
6.4.5. Oculardisease 29
6.4.6. Otherpossiblecomplicationsofhyperlipidemiaindogs 30
6.5. Treatmentofhyperlipidemia indogs 30
6.5.1. Dietarymanagement 31
6.5.2. Medicalmanagement 31

III Publications 34
1. InvestigationofhypertriglyceridemiainhealthyMiniature 34
Schnauzers
1.1. Abstract 35
1.2. Keywords 35
1.3. Introduction 36
1.4. MaterialsandMethods 37
1.5. Results 40
1.6. Discussion 49
1.7. Footnotes 54
1.8. References 55
2. SerumliverenzymeactivitiesinhealthyMiniatureSchnauzers 57
withandwithouthypertriglyceridemia
2.1. Abstract 58
2.2. Abbreviations 58
2.3. Introduction 59
2.4. MaterialsandMethods 60
2.5. Results 62
2.6. Discussion 69
2.7. Footnotes 73
2.8. References 74

IIITableofcontents
IV Discussion 77

V Summary 84

VI Zusammenfassung 86

VII References 88

VIII Legends for tables and figures 105

IX Acknowledgements 106



IVIntroduction
I Introduction
Hypertriglyceridemia, which refers to abnormally increased serum triglyceride
concentrations,isarelativelycommonclinicopathologicfindingindogs.Idiopathic
hypertriglyceridemia appearsto beassociated withspecific breeds,mostcommonly
the Miniature Schnauzer (ROGERS et al., 1975a; WHITNEY, 1992; FORD, 1993;
WHITNEY et al., 1993; BAUER, 2004). Idiopathic hypertriglyceridemia has been
reportedinMiniatureSchnauzersintheUnitedStates,buthasnotbeendocumented
in this breed elsewhere (ROGERS et al., 1975a; WHITNEY, 1992; FORD, 1993;
WHITNEYetal.,1993).ThecauseofhypertriglyceridemiainMiniatureSchnauzers
remainsunclear,butpossiblemechanismsincludeincreasedproductionofVLDLand
chylomicrons,decreasedclearanceofVLDLandchylomicrons,orboth.Thefactthat
hypertriglyceridemia is more prevalent in a specific breed suggests a possible
hereditary mechanism (ROGERS et al., 1975a; FORD, 1993; WHITNEY et al.,
1993). Although it is generally accepted that idiopathic hypertriglyceridemia is a
commondisorderinMiniatureSchnauzersintheUnitedStates,anddespitethefact
that it can potentially be associated with serious diseases (e.g., pancreatitis), it has
received limited attention. The assumption that Miniature Schnauzers have a high
incidence of primary hypertriglyceridemia compared to other breeds is largely
anecdotal or basedonsmallcaseseries (ROGERS et al., 1975a; WHITNEYet al.,
1993).Studiesinvestigatingtheprevalenceandclinicalimplicationsofthiscondition
inlargepopulationsofMiniatureSchnauzersarelacking.Also,theeffectsofage,sex,
and reproductive status on serum triglyceride concentrations have not been
sufficientlystudiedinMiniatureSchnauzers.

Inhumanbeings,hypertriglyceridemiahasbeenassociatedwiththedevelopmentof
fatty liver and a condition known as nonalcoholic fatty liver disease (NAFLD)
(ASSYetal.,2000;ANGULO,2002;NEUSCHWANDER,TETRI&CALDWELL,
2003; DE BRUIN et al., 2004; BROUWERS et al., 2007). The prevalence offatty
liver in patients with hyperlipidemia, including both hypertriglyceridemia and
hypercholesterolemia, has been reported to be about 50% (ASSY et al., 2000;
BROUWERSetal.,2007).MosthumanpatientswithNAFLDremainasymptomatic
1Introduction
forlongperiodsandmanyofthesepatientshaveonlyabnormallyhighserumhepatic
enzyme activities as the initial manifestation of NAFLD (ASSY et al., 2000;
ANGULO,2002;NEUSCHWANDER,TETRI&CALDWELL,2003).Liverenzyme
activitiesareusuallyonlymildlyincreased(i.e.,<2timestheupperreferencelimit),
with high concentrations typically being identified during routine screening
(ANGULO, 2002; NEUSCHWANDER,TETRI & CALDWELL, 2003). Studies
investigating a possible association between hypertriglyceridemia, high serum liver
enzymeactivities,andliverdiseaseindogshavenotbeendescribed.

Thepresentstudyconsistedoftwoparts.Thehypothesisofthefirstpartofthisstudy
wasthathypertriglyceridemiaisprevalentamongMiniatureSchnauzersthatappearto
behealthy.Toproveordisprovethishypothesis,theaimofthisfirstpartofthestudy
was to determine the prevalence of hypertriglyceridemia in a large population of
healthyMiniatureSchnauzersandtofurthercharacterizethisconditioninthisbreed.

Thehypothesisofthesecondpartofthepresentstudywasthathypertriglyceridemia
in overtly healthy Miniature Schnauzers is associated with increased serum liver
enzymeactivities.Toproveordisprovethishypothesisthegoalofthesecondpartof
this study was to measure serum hepatic enzyme activities in healthy
hypertriglyceridemicMiniatureSchnauzers.
2Literaturereview
II Literature review
1. Lipids
Lipids are water,insoluble organic compounds, which are present in almost every
living organism (RIFAI et al., 1999). They are highly polymorphic and chemically
diversebiomolecules,whichmakesitdifficulttodefinethemstructurally(RIFAIet
al.,1999).Lipidsareessentialformanynormalfunctionsoflivingorganisms:they
areimportantcomponentsofcellmembranes,theyareusedtostoreenergy,andthey
play significant roles as enzymecofactors, hormones, and intracellular messengers
(RIFAIetal.,1999).

Ofthe many groups of lipids, threeare mostimportantfromaclinical perspective:
fatty acids, sterols (mainly cholesterol), and acylglyceroles (mainly triglycerides)
(GINSBERG,1998;RIFAIetal.,1999).Fattyacidsarerelativelysimplelipid