PubMed Health⌕ Search

Biomedical subjects

S Visvikis

Publications and source records attributed to S Visvikis.

At least 91 records · Page 5Linked to original sources
PubMed1990

Familial resemblance of plasma apolipoprotein B: the Nancy study.

The familial resemblance of plasma apolipoprotein B (apo B) was investigated in a sample of 102 families including 419 members who volunteered for a free health checkup in the Preventive Center of Vandoeuvre-lès-Nancy, France. The mean levels (+/- SD) of apo B were 141.0 (+/- 32.6), 121.8 (+/- 27.7), and 98.6 (+/- 22.6) mg/dl in fathers, mothers, and offspring, respectively. The familial correlations were 0.04, 0.13, 0.21 (P less than .01), and 0.47 (P less than .001) between spouses, father-offspring, mother-offspring, and siblings, respectively, after adjustment on age, body mass index, and sex. A genetic analysis was performed using the approach proposed by Bonney, which indicated that a recessive and a dominant major-locus model appeared nearly equally supported by the data. Under the recessive model, the frequency q of the most common allele was estimated as 0.825, with a mean difference of 60.4 mg/dl between high and low homozygotes. Under the dominant model, q was estimated as 0.875, with a mean increase of 34.2 mg/dl in heterozygotes and high homozygotes. However, the hypothesis of Mendelian transmission and the environmental hypothesis could not be formally tested because of great numeric difficulties encountered in the estimation of the three transmission probabilities. Given these analytical restrictions, we cannot conclude in favor of a major locus influencing apo B level in our population, even though the evidence is suggestive. The genetic heterogeneity underlying the familial aggregation of apo B level, suggested by several recent publications, might explain the difficulty in discerning a single major locus in a population sample of small nuclear families, not ascertained through patients enriching the sample in high values of apo B. These findings call into question the relevance of the approach through "healthy" populations in the search for major loci influencing biological traits.

Adult↗
PubMed1990

An insertion deletion polymorphism in the signal peptide of the human apolipoprotein B gene.

In this communication we report the genetic properties of an insertion/deletion polymorphism in the signal peptide of the human apolipoprotein B (apo b) gene. There are two alleles of the apo B signal peptide; one codes for a peptide 27 amino acids in length and the other a peptide only 24 amino acids in length. Using the polymerase chain reaction the difference of nine nucleotides between the two alleles is readily detectable after electrophoresis of the amplification products. The relative frequencies of the Ins and Del alleles are 0.655 and 0.345, respectively. The apo B signal peptide genotypes are transmitted in a manner consistent with an autosomal codominant mode of inheritance with two alleles.

Alleles↗
PubMed1990

Frequency and effects of the apolipoprotein A-IV polymorphism.

Plasma from 158 presumed healthy nuclear families has been analyzed by high-resolution, two-dimensional electrophoresis to study the frequency and effects of the genetic polymorphism in human apolipoprotein A-IV. Two common alleles, apo A-IV 1 and apo A-IV 2 were detected with relative frequencies of 0.943 and 0.057, respectively. Autosomal codominant transmission of these two alleles coded for by a single structural locus was demonstrated. Furthermore, we studied the effects of this apo A-IV variability on total plasma cholesterol, triglyceride, glucose levels and gamma-glutamyltransferase activity. Statistically significant differences among apo A-IV genotypes for the average glucose level were detected. The average effect of the apo A-IV 1 allele was to lower plasma glucose levels by 0.013 mmol/l, whereas the average effect of the apo A-IV 2 allele was to raise glucose levels by 0.213 mmol/l.

Adult↗
PubMed1990

Variations in apolipoproteins serum amyloid A, A-I, A-II, and C-III in severely head-injured patients.

In five severely head-injured patients we determined the plasma concentrations of apolipoproteins serum amyloid A, A-I, A-II, C-III, and B, prealbumin and C-reactive protein on day 1, 5, 10 and 15 after head injury where possible. A dramatic increase in apolipoprotein serum amyloid A up to a mean plasma level of 0.764 g/l was accompanied by a considerable decrease in apolipoprotein A-I, apolipoprotein A-II and apolipoprotein C-III concentrations. The variations observed by immunological methods were confirmed by two-dimensional gel electrophoresis performed on plasma and different lipoprotein fractions. In addition to its association with high density lipoproteins, apolipoprotein serum amyloid A was also found with lipoproteins of low and very low density. Two-dimensional electrophoresis also showed the presence of several different serum amyloid A-peptides not seen in plasmas from healthy subjects. We propose that apolipoprotein serum amyloid A may be responsible for the decrease of the main HDL apolipoproteins in head-injured patients.

Apolipoprotein A-I↗
PubMed1990

Biological factors affecting concentrations of serum LpAI lipoprotein particles in serum, and determination of reference limits.

We used an electroimmunoassay to measure LpAI lipoprotein particles (lipoproteins containing apolipoprotein AI but not apolipoprotein AII) in serum of a presumably healthy population of about 1000 subjects, noting sex- and age-related variations for the age interval four to 70 years. Results were higher for women than men. For males, the value for the 50th percentile of the distribution was highest in the 10- to 14-year subgroup, 0.69 g/L, decreasing to 0.60 g/L in adults. For females, the values increased regularly, from 0.59 g/L at ages four to 10 years to 0.79 g/L after age 55 years. The influence of puberty, menopause, oral contraceptives, alcohol consumption, and morphometric characteristics was studied. Only being overweight by more than 20% statistically influenced LpAI values in men and in women. We used these results to select a reference population and to establish reference limits of LpAI at ages 25 to 35 years: 0.40-0.95 g/L for men and 0.46-1.05 g/L for women.

Adolescent↗
PubMed1989

Two-dimensional electrophoresis of plasma proteins and high density lipoproteins during inflammation.

Plasma protein and lipoprotein fractions of five patients were analyzed on day 1, 5, and 15 after severe head injury by combining three types of two-dimensional electrophoresis (2-DE) to obtain information on lipoprotein and apolipoprotein composition. On analysis under nondenaturing conditions in both dimensions on day 5, the samples show modifications of isoelectric point (pI) and molecular weight (Mr) properties of the high density lipoprotein (HDL) fraction in addition to an increase in inflammatory proteins and a return to a normal pattern on day 15. In the second type of 2-DE the samples were analyzed employing isoelectric focusing without denaturant in the first dimension, followed by sodium dodecyl sulfate (SDS) in the second dimension in order to study the protein composition of lipoprotein fractions. On day 5, a decrease of the apolipoproteins apo A-I, apo A-II, and apo C were noted, with simultaneous appearance of an unidentified protein with Mr 12,000 and pI 6.0. In the third type of 2-DE, employing urea and Nonidet P-40 in the first and SDS in the second dimension, the plasma polypeptide composition was studied. The presence of an unidentified polypeptide could be confirmed on day 5, tending to disappear thereafter. This Mr 12,000 component consists of two major spots at pI 5.7 and 6.0 and four minor ones between pI 6.0 and 8.0. These properties suggest that this protein corresponds to serum amyloid A apolipoprotein.

Apolipoprotein A-I↗
PubMed1989

An analysis of genotype effects and their interactions by using the apolipoprotein E polymorphism and longitudinal data.

We investigate the interaction between the apolipoprotein E polymorphism and changes in weight and height as they affect the longitudinal profile of total cholesterol, triglyceride, beta lipoprotein, and glucose levels. Data were available on a sample of 466 individuals in 158 nuclear families from Nancy, France. Longitudinal data analyses were carried out on 128 unrelated adults and 56 unrelated children. We estimate the relative frequencies of the epsilon 2, epsilon 3, and epsilon 4 apolipoprotein E alleles in this population to be .120, .764, and .116, respectively. There is no significant evidence from these data that supports an effect of the apolipoprotein E polymorphism on the longitudinal profile of any of the variables considered. There is a significant interaction between the effects of this gene and weight change on the longitudinal change of serum triglyceride and beta lipoprotein levels in adults. In conjunction with weight gain, individuals with an epsilon 4 allele are expected to show a larger increase in triglyceride levels (0.15 +/- 0.03 mmol/L/kg) compared with individuals with no epsilon 4 allele. An increased production of very-low-density lipoprotein (VLDL) as one gains weight, along with retarded VLDL clearance attributable to the effects of the epsilon 4 allele, may account for this results. The significant interaction between the apolipoprotein E polymorphism and changes in weight on the longitudinal change in triglyceride levels corroborates epidemiological studies reporting that the epsilon 4 allele increases the risk of hypertriglyceridemia among obese individuals.

Apolipoproteins E↗
PubMed1988

[Application of bidimensional electrophoresis in the determination of genetic variants].

Study of the polymorphism of human plasma proteins presents a major advantage in clinical biology to discover abnormal or rare forms, associated with risks or involved with well-specified pathological conditions. If this polymorphism corresponds to structural differences causing a variation of the isoelectric point (Ip) or the molecular weight, it is easily visualized with bidimensional electrophoresis, starting with a few microliters of plasma. On a single mapping per patient, we were able to establish the frequency of various isoforms of Gc globulin, transferrin, haptoglobin, alpha-1-antitrypsin and apolipoproteins E as well as A-IV, in a Lorraine population consulting for a health check-up. This method has already enabled us to demonstrate the effect of polymorphic apolipoproteins on the cholesterol and triglycerides level: patients carrying the epsilon 2 allele of the Apo E, have a mean cholesterol level which is lower than that of the carriers of allele epsilon 3. Patients carrying allele epsilon 4 have the highest mean cholesterol level.

Blood Proteins↗
PubMed1987

The use of measured genotype information in the analysis of quantitative phenotypes in man. II. The role of the apolipoprotein E polymorphism in determining levels, variability, and covariability of cholesterol, betalipoprotein, and triglycerides in a sample of unrelated individuals.

Recent advances in molecular biology provide measures of genotypes at loci involved in lipid metabolism. Genotypes for apolipoprotein E (apo E) and quantitative levels of total plasma cholesterol, betalipoprotein, and triglycerides were measured in a sample of 223 unrelated individuals from Nancy, France. The frequencies of the epsilon 2, epsilon 3, and epsilon 4 alleles are 0.13, 0.74, and 0.13, respectively, in this sample. Significant differences among apo E genotypes were detected for these lipoprotein phenotypes. The average effect of the epsilon 2 allele was to reduce total plasma cholesterol and betalipoprotein levels by 0.52 mmol/L and 0.98, respectively, while the epsilon 4 allele raised these levels by 0.26 mmol/L and 0.61, respectively. Apo E genotype specific correlations suggest that this locus also has an effect on the coordinated metabolism between cholesterol and triglycerides. We infer that approximately 17% of the genetic variability in total plasma cholesterol may be attributable to this apo E polymorphism. No other single locus has been identified with such a large contribution to cardiovascular disease risk factors in the general population.

Alleles↗
PubMed1987

Plasma apolipoproteins in Tangier disease, as studied with two-dimensional electrophoresis.

Tangier disease is characterized by a deficiency of high-density lipoproteins and of their major protein constituent, apolipoprotein (apo) A-I. We used high-resolution two-dimensional electrophoresis to examine the principal plasma apolipoproteins (A-I, A-II, A-IV, E, C-II, and C-III) of three persons with Tangier disease, one homozygous patient and his two heterozygous children, comparing the patterns with those for healthy subjects. Characteristic abnormalities were found in the distribution of the isoproteins of apo A-I, there being a normal concentration of pro apo A-I but dramatically decreased concentrations of the other apo A-I isoproteins. We also found hitherto-undescribed polypeptide abnormalities in apo C-III: sialylated and nonsialylated forms of apo C-III appear as double spots having the same isoelectric points but different molecular masses. No other substantial difference was detected in the polypeptide distribution of the other plasma apolipoproteins.

Adult↗
PubMed1987

Evaluation of lipoproteins and apolipoproteins in serum of a Tangier patient by micro-scale two-dimensional electrophoresis.

We examined lipoproteins and apolipoproteins in serum of a Tangier-disease patient. We used three different techniques of micro-scale two-dimensional electrophoresis: (a) no denaturants; (b) with sodium dodecyl sulfate (SDS) used only in the slab gel electrophoresis; (c) and with urea and a detergent used in isoelectric focusing and with SDS in slab gel electrophoresis. By technique a, an extremely low concentration of high-density lipoproteins (HDL) in the Tangier serum was seen, and lipoproteins that cannot form HDL complexes were detected as multiple spots in the acidic (pl 4 approximately 5) and relatively low apparent molecular mass (20,000 approximately 80,000) region. By technique b, Tangier low-molecular-mass lipoproteins were dissociated into their constituent apolipoproteins, and we observed a higher proportion of apoC-III, together with lower proportions of apoA-I and apoA-II, than in the normal HDL fraction. Technique c showed the total content of apolipoproteins in the whole Tangier serum, as several workers have reported. The presence of low-molecular-mass lipoproteins and a high concentration of apoC-III in this lipoprotein fraction characterized the Tangier serum.

Adult↗
PubMed1986

Immunochemical study of the plasma low and high density lipoproteins in Tangier disease.

Major disturbances of the lipoproteins in Tangier serum have been investigated using electrophoretic and immunochemical techniques. Previously described anomalies concerning the striking deficiency in HDL and the very low levels of apo A-I and apo A-II in Tangier patients are illustrated and explained. Anomalies concerning the fast LDL of Tangier serum are attributed to different forms of apo B not previously described. These data are strengthened by the features of a 2-dimensional electrophoresis method elaborated in the laboratory which allows apoproteins to separate in the second dimension. These apoproteins are obtained by the delipidation of the lipoproteins fractionated in a first polyacrylamide discontinuous gel. This method clearly shows the distribution of apoproteins in the first lipoprotein track and is in perfect accordance with the new concept of lipoprotein particles.

Apolipoprotein A-I↗
PubMedDate not supplied

Decreased high-density lipoprotein cholesterol and serum apolipoprotein AI concentrations are highly correlated with the severity of Alzheimer's disease.

Serum apolipoprotein (apo) AI concentration was studied in 98 Alzheimer's disease (AD) patients (77.56+/-8.83 years) and 59 healthy, elderly controls (75.37+/-5.27 years). ApoAI levels were significantly lower (p<10(-7)) in AD patients. An apoAI cutoff value of 1.50 g/L, could distinguish between the two groups with a sensitivity of 71% and a specificity of 69%. ApoAI levels were highly correlated with mini-mental state (MMSE) scores of patients (p<0.0001). These relationships remained significant after adjustment for multiple testing. Our findings raise the question of the potential implication of apoAI in the etiopathology of AD and bring serum apoAI concentration to the fore as an important biochemical marker.

Aged↗
PubMedDate not supplied

[Apolipoprotein E polymorphism in a Moroccan population: allele frequency and relation to plasma lipid concentrations].

To date, no data are available on relationship between apolipoprotein E (apo E) polymorphism and lipid levels in Moroccan population. The present work reports an apo E polymorphism repartition in Moroccan population and relationship between this polymorphism and the levels of plasma cholesterol, triglycerides, apo A1, B and E. Blood samples from 168 healthy Moroccan individuals from Rabat area (90 men and 78 women), aged from 20 to 50 years (32 9 years), were analysed for serum apo E, A1 and B, triglycerides, and total cholesterol. In parallel, genotyping by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) was performed. The apo E allelic frequencies were 11% for epsilon4, 84% for epsilon3 and 5% for epsilon2. There were correlation between apo E alleles and serum lipid concentrations, E2/E3 carriers had significantly higher level of apo E than E3/E3, and E4/E3 carriers had significantly higher total cholesterol apo B and triglycerides than E3/E3 and E2/E3 carriers. The total cholesterol and apo B concentrations are significantly higher in women than in men but the triglycerides are lower. The apo A1 concentration is independent of both sex and apo E genotype. Thus, the results demonstrate an influence of apo E alleles on serum cholesterol, triglycerides, apo E and apo B concentrations among healthy Moroccan.

Adult↗