Increased apolipoprotein E4 allele frequency is associated with vascular dementia in the Hungarian population

INTRODUCTION

The regulatory role of apolipoprotein E in lipid transport and metabolism was utilized to investigate the allelic association between the apolipoprotein E4 (apoE4) allele and vascular dementia (VD) in a selected sample of Hungarian patients with multiple deep subcortical infarcts and leukoaraiosis.

MATERIAL AND METHODS

Thirty-four Caucasian VD cases and 79 healthy control probands were involved in this study according to the criteria of ICD-10 and NINDS-AIREN International Workshop Diagnostic Criteria. The genomic DNA was isolated from whole blood and the apoE alleles were determined by polymerase chain reaction.

RESULTS

The E2, E3 and E4 allele frequencies in the VD group were 5%, 76%, and 19%, respectively; and significant (P<0.03) differences were found in comparison with the data on the healthy controls (E2, 6%; E3, 87%; E4, 8%). The apoE4 allele frequency was intermediate between HC and Alzheimer's dementia group (28%).

CONCLUSION

These results indicate that the apoE4 allele could be a risk factor not only for certain primary degenerative, but also for vascular dementias.

No mitochondrial haplotype was found to increase risk for Alzheimer's disease

BACKGROUND

Seventy Alzheimer's disease (AD) patients and 80 age- and sex-matched controls were analyzed for mitochondrial mutations T4336C and A3397G, reported to be associated with AD, and for mutations T4216C/G13708A characteristic for a normal human haplotype associated with increased frequency of occurrence of some hereditary diseases. The distribution of apolipoprotein E (apoE) alleles was also analyzed.

METHODS

Mitochondrial DNA was amplified by polymerase chain reaction, and the presence of mutations was detected by digestion with approximately chosen restriction endonucleases (restriction fragment length polymorphism).

RESULTS

One patient and 2 controls were found to belong to the T4336C/T1630C haplotype. No A3397G mutant was detected. The T4216C/G13708A haplotype occurred at 5/70 and 5/80 frequency in the two groups. Prevalence of the apoE4 allele was significantly higher in AD patients (25%) than in the control group (8.1%).

CONCLUSIONS

The T4336C/T16304C mutations were not found to associated with AD, and no predisposing mitochondrial haplotypes were found.

Cytokine regulation of the acute-phase protein levels in multiple myeloma

BACKGROUND

Interleukin (IL) 6 has an important role in the regulation of acute-phase proteins (APPs) during an acute-phase response. We studied IL-6 and other cytokines to determine if they regulate serum APP levels in the same way under the condition of the aberrant, long-lasting 'acute-phase response' that occurs in patients with chronic inflammation and cancer.

METHODS

Serum levels of nine positive APPs [CRP, SAA, C1-INH, Bf, C5, C8, C9, alpha 1-acidic glycoprotein (AGP) and haptoglobin] and two negative APPs [transferrin and alpha 2-HS glycoprotein (AHSG)] were measured using immunochemical methods in 59 multiple myeloma patients and in 72 healthy control subjects. Serum IL-6 and tumour necrosis factor (TNF) alpha levels were determined by bioassays.

RESULTS

IL-6 was negatively correlated with five out of nine (C1-INH, C8, C9, AGP and haptoglobin) positive APPs but positively correlated with C-reactive protein (CRP). When patients with high and low IL-6 serum concentration were compared, CRP levels were higher, AGP and haptoglobin levels were lower in the high- than in the low-L-6 group, whereas no significant difference between the two groups was found in levels of the other positive and negative APPs. TNF-alpha levels were negatively correlated with transferrin and AHSG levels. No difference in the levels of positive APPs was observed between patients with low and high TNF-alpha serum concentration. By contrast, levels of both transferrin and AHSG were significantly lower in the high- than in the low-TNF-alpha group.

CONCLUSIONS

These findings indicate that, except for regulation of the negative APPs by TNF-alpha, the mechanism of APP regulation is different under the conditions of the short-term and the chronic, long-lasting 'acute-phase reaction'.

[Incidence of familial defective apolipoprotein B-100 in cases of patients diagnosed with familial hypercholesterolemia]

Familial Hypercholesterolemia (FH) and Familial Defective Apolipoprotein B-100 (FDB) are monogenic, autosome, dominantly inherited diseases appearing as type II/a primary hypercholesterolemia. The frequency of the heterozygositic forms is 1:700-1:500 in European population. Both forms of hypercholesterolemia causes early onset coronary heart diseases (CHD). According to the recommendations of the international MED-PED program (Make Early Diagnoses--Prevent Early Death), we found 73 FH cases and their 377 first relatives (parents, siblings, children) were also assessed. 156 patients were diagnosed clinically FH (131 alive and 25 deceased), and 31.8% of the males and 32.4% of females suffered from early onset CHD. One family with FH consists of 5.46 members on the average and there are 2.39 FH patients in one family. In our FH cohort four patients with FDB (R3500Q mutation) were diagnosed with allelspecific PCR, and the mutation was detectable also in 9 cases out of 11 living family members. The plasma total cholesterol level of the FDB patients--especially at younger age--was very close to the normal values, which is in contrast to the findings in FH patients. Nevertheless, FDB can be one of the independent causes of the early onset CHD. Therefore, in families with high frequency of cardiovascular diseases the R3500Q mutation has to be considered.

Association of angiotensin II type 1 receptor polymorphism with resistant essential hypertension

Angiotensin II type 1 receptor (AT1) mediates the vasoconstrictive and growth-promoting effect of angiotensin II in humans. It has been reported that a polymorphism of the AT1 gene (an A/C transversion at position 1166: A-C1166) occurs more frequently in resistant hypertensives taking two or more antihypertensive drugs. On the contrary, a recent study of the influence of the A-C1166 polymorphism on aortic stiffness demonstrated that the distribution of the genotypes did not differ between normotensive and hypertensive subjects. In addition, a recent population-based survey of Caucasian hypertensives reported lower blood pressure values in CC homozygotes than in heterozygotes and AA homozygotes. Because of these controversial results and the lack of a sufficient amount of data the present study was designed to assess the contribution of the AT, gene A-C1166 polymorphism to resistant essential hypertension. Forty-eight subjects with resistant essential hypertension (HT) and 48 normotensive (NT), age and sex-adjusted controls (from a population of 300 healthy blood donors) were selected. All subjects were genotyped for the A-C1166 polymorphism in the 3'-UTR of the AT1 gene using PCR-based techniques. The influence of genotype on blood pressure (BP) was investigated using ANOVA Randomized Complete Block (ANOVA RCB) design according to sex, age and BMI. There were no significant differences in allele or genotype frequencies between HT and NT subjects (X2 = 0.61; P = NS). In HT subjects higher values of systolic blood pressure were associated with the C allele of the AT1 gene only in older and overweight patients (P < 0.001 and P < 0.001, respectively). Also in HT patients an association between the presence of the C allele of the AT1 gene and higher values of diastolic blood pressure was present in overweight patients (P = 0.001). These results suggest that in resistant hypertensive subjects the AT1 A-C1166 polymorphism is potentially involved in the regulation of blood pressure. As the effects of genotypes on blood pressure are pronounced in older and overweight subjects this polymorphism may amplify the effects of age and BMI on resistant essential hypertension.

[Characteristics of apolipoprotein polymorphism in a Hungarian population]

One of the main risk factors of ischaemic heart disease is the dyslipidaemia. In the development of altered lipid metabolism genetic factors play a significant role. The hereditary backgrounds have to be known in order to reveal the most important possibilities in diagnostics and prevention.

Association of the apolipoprotein A-IV codon 360 mutation in patients with Alzheimer's disease

Specific apolipoprotein E (apoE) alleles determines, in large part, the risk and mean age of onset familial and sporadic Alzheimer disease. The unresolved issues in this relationship support the contribution of other environmental and genetic parts. Among the candidates the apolipoprotein A-IV (apoA-IV) a component of plasma lipid particles similar to apoE has been suggested to play a role in brain metabolism. Since apoA-IV has a common DNA based protein polymorphism with a different function we determined apoA-IV (360:Gln:His) DNA polymorphism in 63 late-onset sporadic Alzheimer's patients. We found that the APOA-IV (360:His) heterozygosity occurs significantly more frequent (20.6% vs. 7.0%, P = 0.021, odds ratio 3.4 (confidence interval 1.1-10.2)) comparing age-matched controls with normal mental score. The significant difference in apoA-IV allelic distribution has been detected dominantly in patients with non-apoE4 genotype. Our data indicate that the apoA-IV-2 allele may confer one of the susceptibility markers for Alzheimer's disease (AD) and strengthen the polygenic risk determination of the variability in expression of AD.

[Study of low density lipoprotein (LDL) receptor mutations, using restriction endonucleases, in familial hypercholesterolemia]

Familial hypercholesterolemia (FH) is an autosomal dominant metabolic disorder caused by different mutations in the low density lipoprotein receptor (LDLR) gene. We analyzed 13 families (23 patients) with FH and 36 subjects with normocholesterolemia by restriction fragment polymorphism (RFLP) using enzymes Xbal, BgIII and PvuII. At the 3' end of LDLR an extra 4.4 kb band has been found by Xbal digestion in one patient and it has been proved to be a "de novo" form of mutation. In the 5' end of LDLR gene a combined mutation has been identified in two FH families. The Xbal RFLP has yielded an extra band of 24.5 kb and an another extra band of 17.5 kb has been found by BgIII digestion. It has been suggested that the simultaneous occurrence of 3.3 kb extended deletion (intron 3) and 4.8 kb extended insertion (intron 1) is present. In our study the frequency of P2 allele (PvuII RFLP) in FH patients did not differ from normocholesterolemic controls.

Apolipoprotein E allele frequencies in patients with late-onset sporadic Alzheimer's dementia in Hungary

INTRODUCTION

The presence of the apolipoprotein E4 allele (apoE4) has been recognized as a risk factor for the development of presenile and senile forms of Alzheimer's dementia (AD).

MATERIAL AND METHODS

The apoE alleles frequency of 71 normal controls (NC), 60 demented controls (DC) and 50 senile type AD subjects was determined by polymerase chain reaction in order to get data about the apoE polymorphism of the Hungarian AD population.

RESULTS

The apoE3/3 genotype was the most common in all groups. The apoE4 frequency was significantly higher (28%) in the AD group than that was (7% and 9%) in the NC and DC populations, respectively. No apoE4 homozygotes were found in the DC group and the number of heterozygotes was lower in the DC than in the AD group.

CONCLUSION

The results are in good agreement with others in the literature and support the occurrence of an increased apoE4 allele frequency in Hungarian senile AD population.

Lipoprotein(a) concentration and phenotypes in primary biliary cirrhosis

We studied a selected group of 39 female patients suffering from primary biliary cirrhosis (PBC). This disease is characterized by typical lipoprotein alterations and elevated concentrations of serum cholesterol. Despite the increased concentration of atherogenic lipoproteins, enhanced atherogenesis is not characteristic of PBC. Serum total cholesterol, triglycerides, HDL2 and HDL3-cholesterol concentrations were measured by enzymatic methods or in combination with precipitation procedures. Apolipoproteins were determined by using immunonephelometric methods. ELISA sandwich method was used for lipoprotein(a) determinations. Apoprotein(a) phenotyping (isoforms) was performed by Western blotting with specific antibodies. The concentrations of serum lipids, lipoproteins and apoproteins (AI, AII and B) were found in the range of earlier investigations. The serum lipoprotein(a) concentration did not differ between the PBC patients and control subjects (10.0/0.1-54/, median 2.55 vs. 11.5/0-75/, median 5.2 mg/dl). In the advanced stages of PBC we found a higher number of patients with low lipoprotein concentration (lower than 1 mg/dl). In patients with shorter durations and milder histological alterations high HDL2 cholesterol subfractions has been detected (stage I = 0.42 +/- 0.18, stage II = 0.53 +/- 0.29 and stage III = 0.62 +/- 0.41 vs. stage IV = 0.26 +/- 0.15 mmol/l, P < 0.05). Despite the elevation of atherogenic lipoproteins, high HDL2-cholesterol and normal lipoprotein(a) concentrations may be one of the reasons why patients with advanced PBC are not placed at increased risk for atherosclerosis.

High lipoprotein(a) levels with predominance of high molecular weight apo(a) isoforms in patients with pulmonary embolism

Lipoprotein(a) (Lp(a)) may interact with the cellular components and protein co-factors of fibrinolysis. To evaluate the effect of Lp(a) in thromboembolic diseases of the venous system, we measured serum levels and the isoform distribution of apo(a) in 25 patients with pulmonary embolism (18 men, 7 women, aged 21-77 years). The control group was adjusted for sex and age (P = 0.189). Serum Lp(a) concentration was significantly higher in the study group (median: 9.3 vs. 4.3 mg dL-1). As the distribution of high and low molecular weight subtypes of apo(a) did not show any differences (P = 0.127) between the two groups, the elevated Lp(a) levels in patients with pulmonary embolism could not be attributed to the investigated kringle-4 polymorphism of the apo(a) gene and therefore other genetic or non-genetic implications are indicated.

Kringle 4 of human apolipoprotein[a] shares a linear antigenic site with human catalase

Monoclonal antibody (mab) 1A2, directed against human apolipoprotein[a] (apo[a]), revealed a strong reaction with peroxisomes as shown by immuno-gold labeled cryosections of human liver biopsies. This reactivity was not due to the presence of apo[a] in peroxisomes but to a cross-reactivity of mab 1A2. Immunoblot analysis of peroxisomal fractions and purified human catalase demonstrated that mab 1A2 reacts with catalase. Conversely, an anti-catalase antibody also recognized apo[a]. By sequence comparison we identified a 4-amino acid motif (Y-Y-P-N) that is shared between the highly repetitive kringle 4 motif of apo[a] and the carboxy-terminal third of the peroxisomal marker enzyme catalase. No other identical sequences were identified in these proteins. Results from the following experiments indicated that 1A2 recognizes this short linear epitope. i) Mab 1A2 reacted only with the 4 amino acid peptide sequence in a pin-ELISA using immobilized overlapping peptides. ii) A synthetic peptide including this sequence completely inhibited the 1A2 immunoreactivity to apo[a] and catalase. iii) A recombinant fusion protein tagged with the putative epitope was recognized by mab 1A2. Our findings demonstrate that unknown linear epitopes in native proteins can be identified by sequence comparison between known proteins. The practical implication is that antibodies against apo[a] must be controlled for this cross-reactivity before using them for immunohistochemical studies of intracellular apo[a] in tissues or cells.

Apolipoprotein A-IV polymorphism in the Hungarian population: gene frequencies, effect on lipid levels, and sequence of two new variants

The genetic polymorphism of human apolipoprotein A-IV was investigated in Hungarian blood donors (n = 202) by isoelectric focusing (IEF) of plasma samples followed by immunoblotting. The frequency of apo A-IV alleles was f(A-IV1) = 0.95, f(A-IV2) = 0.039 and f(A-IV3) = 0.002. This frequency distribution is significantly different from other Caucasian populations (P < 0.05). The association of apo A-IV phenotypes with HDL-cholesterol concentration which was previously described for two other European populations was only of borderline significance (P = 0.08). Three previously undescribed apo A-IV variants, designated Budapest-1, Budapest-2 and Budapest-3, were detected by IEF. The mutant proteins are not associated with alterations in the lipid/lipoprotein concentrations in heterozygotes. DNA-sequencing revealed two point mutations (Arg285-->Cys and Thr347-->Ser) in exon 3 of apo A-IV-Budapest-1 and a Glu-->Lys substitution at position 24 in exon 2 of apo A-IV-Budapest-2.

Plasma lipoprotein (a) concentration and phenotypes in diabetes mellitus

Patients with Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus are at increased risk of developing atherosclerotic vascular diseases. A variety of lipoprotein abnormalities have been described as being associated with this increased risk. In this study, apo(a) isoform frequencies and lipoprotein(a) [Lp(a)] concentrations were determined in Type 1 and Type 2 diabetic patients in order to investigate a possible contribution of Lp(a) to the increased risk for atherosclerosis in diabetes. No significant differences in plasma Lp(a) concentrations were found in two ethnically different populations (Austrians from the province of Tyrol and Hungarians from Budapest) in either type of diabetes when compared to respective control groups (91 Type 1 and 112 Type 2 diabetic patients vs 202 control subjects in the Hungarian study and 44 Type 1 diabetic and 44 Type 2 diabetic vs 125 control subjects in the Austrian study). There were also no significant apo(a) isoform frequency differences between both patient groups and control subjects in the two study groups. These data, obtained from two large ethnically different populations, provide no evidence of a contribution of Lp(a) to the increased risk for atherosclerosis in diabetes.

[Distribution of apolipoprotein A I and B in the blood according to age and gender, as well as their relation to blood cholesterol levels in the Hungarian blood donor population]

In this study we assessed the plasma CHOL, HDL cholesterol (HDL-C), apoprotein A I, apoprotein B levels and the polymorphic isoforms of apoprotein A I in Hungarian blood donors (n = 202, average age: 37.5 year). The mean values are presented for age and sex groups, and the data are compared to the international measurements. The mean CHOL concentration was 5.7 +/- 1.1 mmol/l. The CHOL level correlated with age and no significant association was observed with sex. The level of HDL-C showed no correlation with the age and--in opposite to the international data--there were no significant sex differences (women: 1.42 +/- 0.45, men: 1.34 +/- 0.44 mmol/l), which may be explained by the relative high HDL-C concentration of Hungarian men. Both apo A I and apo B showed an increase with advancing age. The only difference between the sexes was found in apoprotein A I levels, i. e. it was higher in women than in men (women: 156.3 +/- 23.6, men: 143.8 +/- 26.8 mg/dl). In contrary with the results from other countries, the apoprotein B concentrations in men did not differ from that measured in women (women: 72.1 +/- 17.4, men: 69 +/- 15.8 mg/dl). In relation to the age, in the fifth decade the CHOL, the HDL-C and the apo B levels were higher in women than in men.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the apolipoprotein(a) size polymorphism on the lipoprotein(a) concentration in 7 ethnic groups

Apolipoprotein(a) [apo(a)] exhibits a genetic size polymorphism explaining about 40% of the variability in lipoprotein(a) [Lp(a)] concentration in Tyroleans. Lp(a) concentrations and apo(a) phenotypes were determined in 7 ethnic groups (Tyrolean, Icelandic, Hungarian, Malay, Chinese, Indian, Black Sudanese) and the effects of the apo(a) size polymorphism on Lp(a) levels were estimated in each group. Average Lp(a) concentrations were highly significantly different among these populations, with the Chinese (7.0 mg/dl) having the lowest and the Sudanese (46 mg/dl) the highest levels. Apo(a) phenotype and derived apo(a) allele frequencies were also significantly different among the populations. Apo(a) isoform effects on Lp(a) levels were not significantly different among populations. Lp(a) levels were however roughly twice as high in the same phenotypes in the Indians, and several times as high in the Sudanese, compared with Caucasians. The size variation of apo(a) explains from 0.77 (Malays) to only 0.19 (Sudanese) of the total variability in Lp(a) levels. Together these data show (I) that there is considerable heterogeneity of the Lp(a) polymorphism among populations, (II) that differences in apo(a) allele frequencies alone do not explain the differences in Lp(a) levels among populations and (III) that in some populations, e.g. Sudanese Blacks, Lp(a) levels are mainly determined by factors that are different from the apo(a) size polymorphism.