CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 1, January/February 2013
284
AFRICA
pressure overload.
Methods:
RV pressure overload was induced by partial pulmonary
arterial banding (PAB) in three-week-old rats. The rats were divided
into two groups: mild pulmonary stenosis (PS) group (20–40% steno-
sis,
n
=
20) and severe PS group (40–70% stenosis,
n
=
28). Sham-
operated animals (sham group,
n
=
30) underwent the same surgical
procedure without PAB.
Pressure-overloaded RV hypertrophy, which
was documented by weighing the heart, evaluation of echocardio-
grams, and cardiac hypertrophy-associated gene expression. The RV
MPI was checked one, two, three, five, and eight weeks after PAB.
Results
: The RV MPI of the mild PS group did not differ signifi-
cantly from that of the sham group. The RV MPI of the severe PS
group, however, was paradoxically lower than that of the sham group
(
p
<
0.05).
Conclusions:
The RV MPI was paradoxically deceased in severe RV
pressure overload hypertrophy induced by PAB.
898: GLYCOGEN KINASE-3 INHIBITION: GOOD OR BAD
FOR THE HEART?
Barbara Huisamen
1
, Brian Flepisi
2
, Tandekile Lubelwana-Hafver
1
1
Division of Medical Physiology, Faculty of Medicine and Health
Sciences, University of Stellenbosch, Tygerberg, South Africa
2
Department of Pharmacy, Faculty of Medicine and Health Sciences,
University of Stellenbosch, Tygerberg, South Africa
Background:
Glycogen synthase kinase-3 (GSK-3) is a serine-thre-
onine kinase that was discovered as a regulator of glycogen synthase
and known as a role player in cardioprotection. Myocardial GSK-3
(1) may regulate expression of SERCA-2a, affecting contractility; (2)
may phosphorylate and inhibit IRS-1, disrupting insulin signalling,
(3) may regulate growth via interaction with Wnt and hypertrophic
signalling pathways. GSK-3 inhibitors are being developed for clini-
cal use.
Aim:
To determine whether myocardial GSK-3 and its substrate
proteins are dysregulated in obesity and pre-diabetes, and to study the
effects of GSK-3 inhibition on the hearts of obese, pre-diabetic rats.
Methods:
Pre-diabetic Wistar rats [induced by a diet causing
hyperphagia (DIO) for 16 weeks] were compared to age-matched
controls. Half of each group was treated with the GSK-3 inhibitor
(CHIR118637 – 30 mg/kg/day) for four weeks (weeks 12 to 16 of
the diet period). After 16 weeks, echocardiography was performed
and glucose tolerance was established, biometric and biochemical
parameters were determined, myocardial performance was veri-
fied by
ex vivo
perfusion, and protein expression was ascertained
in snap-frozen hearts by Western blotting and specific antibodies.
Ca
2
+
ATPase activity was determined spectrophotometrically and
cardiomyocytes were used to determine cell size and localisation of
NFATc3 and GATA4.
Results:
Treated and untreated DIO gained more body weight and
intra-peritoneal fat. GSK-3 inhibition improved glucose tolerance
and echo parameters in DIO. CHIR had no effect on GSK-3 expres-
sion but increased phosphorylation in CHIR. CHIR was associated
with increased NFATc3 and GATA4 nuclear translocation. CHIR
elevated IRS-2 expression but had no effect on IRS-1 and SERCA-
2a.CHIR increased PKB/Akt and phospholamban phosphorylation
in DIO rats.
Conclusion:
GSK-3 protein may play a role in glucose homeostasis
and regulation of IRS-2 expression but its inhibition did not enhance
IRS-1 or SERCA-2a expression. CHIR reversed cardiac hypertrophy
in DIO rats but it caused hypertrophy in the controls.
907: GENETIC POLYMORPHISMS ASSOCIATED WITH
ALLOGENEIC RED BLOOD CELL TRANSFUSION
REQUIREMENTS IN PAEDIATRIC PATIENTS UNDERGO-
ING CARDIAC SURGERY
Cedric Manlhiot, Colleen E Gruenwald, Seema Mital, Helen M
Holtby, Ashok K Manickaraj, V Ben Sivarajan, Steven M Schwartz,
Christopher A Caldarone, Brian W McCrindle
The Hospital for Sick Children, University of Toronto, Toronto,
Canada
Background:
Patients undergoing repair of congenital heart disease
require allogeneic blood transfusions, mainly to allow cardiopulmo-
nary bypass and to offset blood loss from bleeding. Clinical factors
associated with increased bleeding risk, including coagulation
system activity, platelet reactivity, use of deep hypothermic circu-
latory arrest, and surgery duration and complexity. We sought to
determine whether genetic polymorphisms known to be associated
with the coagulation/fibrinolytic system or with platelet function are
associated with red blood cell transfusion requirements associated
with paediatric cardiac surgery.
Methods:
A total of 625 cardiac surgeries in 383 patients were
reviewed. Ninety-six SNPs on 53 genes involved in the coagula-
tion/fibrinolysis pathways were assayed using the the Illumina
GoldenGate
®
custom SNP panel; genotyping was successful for
>
99% of SNPs. Associations between SNPs and red blood cell transfu-
sions within 48 hours of surgery (adjusted for age at surgery, surgical
complexity and pre-operative oxygen saturation) were assessed in
regression models adjusted for repeated measures. Bootstrap resa-
mpling (1 000 samples) was used to offset multiple comparison bias
and exclude SNPs with very low minor allele frequencies.
Results:
Median red blood cell requirement was 114 ml/kg (interquar-
tile range: 73–174 ml/kg). Coagulation factor polymorphisms associ-
ated with increased red blood cell requirements included factor VIII
rs100873005 CC/CG SNPs [
+
40 (14) ml/kg,
p
=
0.004] and factor
XI rs2036914 CC SNPs [
+
51 (16) ml/kg,
p
=
0.001]. Additional
SNPs associated with a higher volume of red blood cell require-
ments included alpha-2-macroglobulin precursor rs669 GG SNPs
[
+
91 (23) ml/kg,
p
<
0.001], guanine nucleotide-binding protein
β
3
rs5443 CC SNPs [
+
35 (18) ml/kg,
p
=
0.05] and chemokine receptor
2 rs1799864 AA/AG SNPs [
+
42 (16) ml/kg,
p
=
0.008]. Both alpha-
2-macroglobulin precursor rs669 and factor XI rs2036914 were also
found to be associated with low pre-operative antithrombin activity,
a key marker of heparin resistance and increased bleeding volumes.
Conclusions:
Patients with congenital heart disease have substantial
transfusion requirements during and immediately after paediatric
cardiac surgery. While clinical factors are critical in determining the
required amount of transfusions, genetic polymorphisms also have a
key role in this process.
908: ASSESSING THE INTERLEUKIN-6 -174 G/C SINGLE
NUCLEOTIDE POLYMORPHISM AND CORONARY
ARTERY DISEASE
Alisa Phulukdaree
1
, Sajidah Khan
2
, Devapregasan Moodley
3
,
Prithiksha Ramkaran
1
, Rishalan Govender
1
, Anil Chuturgoon
1
1
Department of Medical Biochemistry, University of KwaZulu-Natal,
South Africa
2
Department of Cardiology, University of KwaZulu-Natal, South
Africa
3
Division of Immunology, Harvard Medical School, Boston MA, USA
Background:
Interleukin 6 (IL6) is a pro-inflammatory cytokine
involved in the pathogenesis of chronic inflammatory diseases such
as coronary artery disease (CAD). The -174 IL6 G/C promoter poly-
morphism influences mRNA and protein levels and is implicated in
CAD. This polymorphism has been investigated but limited data are
available on South African Indian (SAI) and black (SAB) population
groups, despite high disease prevalence. This study aimed to assess
the -174 IL6 G/C polymorphism in SAI subjects with CAD.
Methods:
Polymorphic variants were assessed by polymerase chain
reaction–restriction fragment length polymorphism, and IL6 levels
were measured by ELISA.
Results:
The -174 IL6 C allele was found at a higher frequency in
the total SAI subjects (23%) compared to SABs (2%), irrespective
of disease status (
p
<
0.0001, OR
=
0.0503, 95% CI: 0.0183–0.1388)
and in healthy SAI (29%) and SAB (2%) controls (
p
<
0.0001, OR
=
0.0507, 95% CI: 0.0152–0.1699). A significant association between
