Search PubMed⌕ Search

Biomedical subjects

K Kontula

Publications and source records attributed to K Kontula.

At least 127 records · Page 7Linked to original sources
PubMed1991

DNA polymorphisms of apolipoprotein B and AI/CIII genes and response to gemfibrozil treatment.

Apolipoprotein B XbaI polymorphism and apolipoprotein AI/CIII SstI polymorphism have been found to be associated with variations in serum lipoprotein levels. We investigated whether these gene polymorphisms are involved in determining the lipid-modulating action of gemfibrozil. Of the 221 male subjects with hyperlipidemia studied, 121 responded well to the treatment with more than a 25% reduction in the non-high-density lipoprotein cholesterol level, whereas 100 were nonresponders. Among responders, but not nonresponders, homozygosity for the apolipoprotein B X2 allele (XbaI site present) and heterozygosity for the apolipoprotein AI/CIII S2 allele (SstI site present) were associated with elevated baseline serum low-density lipoprotein cholesterol and triglyceride levels, respectively. However, the hypolipidemic effect of gemfibrozil among the responders was independent of these gene polymorphisms. These data indicate that common polymorphisms of the apolipoprotein B and apolipoprotein AI/CIII gene loci influence serum lipid levels by mechanisms that are amenable to an intervention with gemfibrozil.

Adult↗
PubMed1991

Physical exercise after alcohol intake: effect on plasma catecholamines and lymphocytic beta-adrenergic receptors.

The combined effects of alcohol intoxication and intense physical exercise on the adrenergic system were studied in eight healthy male volunteers. Ethanol (0.8 g/kg body weight) was administered perorally to bring about a mean serum concentration of 21 mmol/liter (0.1%); each subject also participated in an identical control session without alcohol. Acute alcohol intake alone did not change the concentrations of plasma adrenaline or noradrenaline or the density, affinity, and functioning (ability to mediate catecholamine-stimulated production of cAMP) of lymphocytic beta-adrenergic receptors. In contrast, acute ergometer exercise brought about an approximately 10-fold increase of plasma adrenaline and noradrenaline concentrations, a 2- to 3-fold increase of beta-adrenergic receptor density and an enhancement of isoproterenol-stimulated cAMP production. Alcohol intake immediately before the ergometer exercise did not modify these changes. In conclusion, acute physical exercise activates the human adrenergic system, with an increase of both plasma catecholamines and lymphocytic beta-adrenergic receptors. Moderate alcohol intoxication does not affect exercise-induced alterations of these parameters.

Adult↗
PubMed1991

Association of apolipoprotein E and B polymorphisms with serum lipids.

Genetic polymorphism of apolipoprotein E (apoE) and the Xbal restriction-fragment-length polymorphisms (RFLP) of the gene for apolipoprotein B (apoB) have both been shown to be associated with plasma lipid concentration. We studied the combined effect of these gene polymorphisms on serum cholesterol concentrations in 300 subjects aged nine to 18 years. In three way ANOVA, there was a statistically significant interaction between the effects of apoE phenotype and gender on serum cholesterol (P = 0.009). Therefore, males and females were analysed separately by two way ANOVA: there was no interaction between the effects of apoE phenotype and apoB Xbal polymorphism in either gender. In females, there were independent effects of both the apoE phenotype (P = 0.020) and the apoB Xbal genotype (P = 0.037) on serum cholesterol, but in males these effects were not statistically significant. These data suggest that variations at the apolipoprotein B and E gene locus play a role in the determination of serum cholesterol concentration in young female Finns.

Adolescent↗
PubMed1991

DNA polymorphisms of the apolipoprotein B and A-I/C-III genes are associated with variations of serum low density lipoprotein cholesterol level in childhood.

A number of restriction fragment length polymorphisms (RFLPs) of the apolipoprotein B (apoB) and apolipoprotein A-I/C-III(apoA-I/C-III) genes have been found to be associated with serum lipoprotein levels in many adult populations. In order to examine whether these genetic polymorphisms influence serum lipoprotein levels in childhood and adolescence, we determined the apoB XbaI and apoA-I/C-III SstI genotypes and serum lipoprotein concentrations in 307 healthy Finns aged 9 to 21 years. In the age groups of 9, 12, and 15 years, subjects homozygous for the X2 allele (the XbaI site present) of the apoB gene had mean serum low-density lipoprotein (LDL) cholesterol levels (3.69, 3.43, and 3.15 mmol/l, respectively) that were 12-20% higher than those in subjects homozygous for the absence of this allele (3.08, 3.02, and 2.80 mmol/l, respectively). This association was more significant in males than in females. At the age of 9 to 18 years, subjects carrying the S2 allele (SstI site present) of the apoA-I/C-III gene complex had an approximately 6-15% higher mean serum LDL-cholesterol level than those homozygous for its absence. The combined genotype X2+S2+ (the simultaneous presence of the X2 allele and the S2 allele) was associated with an even more marked elevation of serum LDL-cholesterol level than either allele alone. As an example, the serum LDL cholesterol concentration was 20% higher in 9-year-old subjects with at least one X2 and one S2 allele than in those without either allele (3.55 vs. 2.97 mmol/l, P less than 0.005). The S2 allele was found to be significantly more frequent in eastern than in western Finland, whereas no significant areal differences were seen in the occurrence of the X2 allele. In conclusion, genetic variations of the apoB and apoA-I/C-III gene loci influence serum lipoprotein concentrations already in childhood.

Adolescent↗
PubMed1990

Absence of familial defective apolipoprotein B-100 in Finnish patients with elevated serum cholesterol.

Familial defective apolipoprotein B-100 is a genetic disorder which is associated with elevated plasma LDL levels. It appears to result from a G----A mutation at nucleotide 10,708 in exon 26 of the apolipoprotein B-100 gene leading to a substitution of glutamine for arginine at amino acid residue 3500. We explored the possible role of this point mutation as a cause of elevated plasma cholesterol among the Finns, a genetically isolated population in which both hypercholesterolemia and coronary heart disease are common: 552 hyperlipidemic patients from Western and Southern Finland were screened either by assaying patient sera with monoclonal antibody MB47 or by amplifying the region of the apo B gene containing the nucleotide 10,708 followed by hybridization of the amplified DNA with allele-specific oligonucleotide probes. Not a single individual with this particular mutation could be found. We conclude that familial defective apo B-100 is not a common cause of elevated plasma cholesterol in this population.

Apolipoprotein B-100↗
PubMed1990

A primer-guided nucleotide incorporation assay in the genotyping of apolipoprotein E.

We describe a new technique by which single base changes in human genes can be conveniently detected. In this method the DNA fragment of interest is first amplified using the polymerase chain reaction with an oligonucleotide primer biotinylated at its 5'-end. The amplified 5'-biotinylated DNA is immobilized on an avidin matrix and rendered single-stranded. The variable nucleotide in the immobilized DNA is identified by a one-step primer extension reaction directed by a detection step primer, which anneals to the DNA immediately upstream of the site of variation. In this reaction a single labeled nucleoside triphosphate complementary to the nucleotide at the variable site is incorporated. The method is highly sensitive, allowing the use of nucleoside triphosphates labeled with radioisotopes of low specific activity (3H) as well as nonradioactive markers (digoxigenin). The procedure consists of few and simple operations and is thus applicable to the analysis of large numbers of samples. Here we applied it to the analysis of the three-allelic polymorphism of the human apolipoprotein E gene. We were able to correctly identify all possible combinations of the three apo E alleles.

Apolipoproteins E↗
PubMed1990

Effect of propranolol and pindolol on the up-regulation of lymphocytic beta adrenoceptors during acute submaximal physical exercise. A placebo-controlled double-blind study.

The effect of beta-adrenoceptor antagonists, with and without intrinsic sympathomimetic activity, on the regulation of lymphocytic beta adrenoceptors during acute physical exercise was studied. Seven healthy volunteers underwent a graded maximal ergometer test after treatment for 7 days with placebo, propranolol (2 x 80 mg/day), or pindolol (2 x 10 mg/day). Each subject received the three types of drug treatment in a double-blind, randomized fashion, with 3 weeks wash-out periods between the on-drug periods. The mean resting density of lymphocytic beta adrenoceptors was 46 +/- 5 fmol/mg protein (mean +/- SEM) during placebo, 53 +/- 5 fmol/mg protein during propranolol, and 29 +/- 4 fmol/mg protein during pindolol treatment (p less than 0.05, pindolol vs. propranolol). Exercise induced a significant up-regulation of the beta-adrenoceptor density during each treatment modality, but the increment was attenuated during propranolol (mean elevation, 16 +/- 2 fmol/mg protein, p less than 0.05) and pindolol intake (13 +/- 4 fmol/mg protein, p less than 0.02) as compared with the placebo value (56 +/- 13 fmol/mg protein). Moreover, exercise-induced increment of lymphocytic cyclic AMP (cAMP) production was virtually abolished by the two beta-adrenoceptor antagonists. In conclusion, administration of beta-adrenoceptor antagonists is associated with a subnormal up-regulation of the lymphocytic beta-adrenoceptors and alterations in their functioning during heavy physical effort. This attenuation is not modified by intrinsic sympathomimetic activity of the compound.

Adult↗
PubMed1990

Human granulosa cells contain insulin-like growth factor-binding protein (IGF BP-1) mRNA.

Previous studies have demonstrated expression of insulin-like growth factor-binding protein (IGF BP-1) in secretory and decidualized endometrium, in adult and fetal liver, and in HepG2 liver cancer cells. We have studied the expression of IGF BP-1 in various types of ovarian neoplasias, normal ovary, and granulosa cells from hyperstimulated human ovarian follicles by RNA blot hybridization. A single 1.6 kb mRNA species, similar to that present in human decidua, was identified in poly(A)RNA-containing preparations of granulosa cells and of a borderline malignant ovarian cystadenoma. This finding verifies the postulated production of IGF BP-1 by the human ovary.

Adult↗
PubMed1990

Reduction of lymphocytic beta-adrenoceptor level in chronic alcoholics and rapid reversal after ethanol withdrawal.

Plasma catecholamine levels, lymphocytic beta-adrenoceptor densities and lymphocytic cAMP production were studied in 10 male subjects attending a withdrawal clinic after prolonged alcohol abuse. On admission the mean beta-adrenoceptor density was 29 +/- 9 fmol mg-1 protein (about 60% of the mean level of healthy control subjects, P less than 0.002). The following day a significant elevation of the beta-adrenoceptor level up to 46 +/- 19 fmol mg-1 protein (P less than 0.05) took place. This was accompanied by a parallel activation of the beta-adrenoceptor-mediated cAMP production of the lymphocytes. No major changes in beta-adrenoceptor levels or cAMP production took place during the next 7 days. Plasma catecholamine levels were elevated at arrival and decreased steadily during the withdrawal period. In conclusion, chronic alcoholism is associated with a reduction of lymphocytic beta-adrenoceptor density and functioning, which is followed by a rapid reversal during abrupt ethanol withdrawal. Thus an accelerated responsiveness to catecholamines may occur during the first ethanol-free day of chronic alcoholics.

Adult↗
PubMed1990

The beta-adrenergic system in man: physiological and pathophysiological response. Regulation of receptor density and functioning.

Catecholamines play an essential role in the activation of the cardiovascular system and in the regulation of energy metabolism in a variety of physiological conditions. Many of these effects are mediated through beta-adrenoceptors located on cell membranes. Binding of catecholamines to beta-adrenoceptor increases the concentration of intracellular cyclic AMP which in turn activates protein kinase A. This enzyme phosphorylates a number of other intracellular enzymes influencing cell metabolism and functions. The primary structures of the receptor and its topography in the cell membrane as well as its binding domains have been partially clarified. In studies of the human beta-adrenergic receptors blood lymphocytes have mostly been used as model cells. These cells carry receptors of mainly the beta 2-subtype. The adequacy of this model system has been demonstrated in several studies. In clinical work receptor assays have had limited use until now. However, studies on the pathophysiology of the adrenergic system in several diseases have revealed that receptor alterations may constitute an important factor in the disease process. Measurements of adrenergic receptors may also have increasing usefulness in determining optimal drug concentrations. Our own studies have primarily focused on physiological adjustments in the beta-adrenergic system during acute or prolonged physical exercise as well as receptor changes in heart failure, muscle diseases and the alcohol withdrawal syndrome. We have also explored receptor dynamics during therapy with beta-blocking agents. These studies, briefly reviewed in this communication, have led to the following conclusions: (1) High aerobic capacity is associated with an increased density and ability of lymphocytic beta-adrenoceptors to respond to catecholamines. (2) Both short-and long-term physical exercise induce a rapid up-regulation and more effective functioning of lymphocytic beta-adrenoceptors. (3) Administration of beta-blocking drugs is associated with a subnormal exercise-induced up-regulation and decreased functioning of the lymphocytic beta-adrenoceptors. (4) The exercise-provoked up-regulation and improved functioning of beta-adrenoceptors is blunted in heart failure patients. (5) Patients with Duchenne-type of muscular dystrophy have a reduced number of lymphocytic beta-adrenoceptors. (6) In chronic alcoholics the lymphocytic beta-adrenoceptor level is subnormal but during abrupt ethanol withdrawal a rapid increase in the number and functioning of the receptors to a normal level takes place. This sequence of events may lead to a condition of relative adrenergic hypersensitivity.

Adrenal Gland Neoplasms↗
PubMed1990

Apolipoprotein E polymorphism determined by restriction enzyme analysis of DNA amplified by polymerase chain reaction: convenient alternative to phenotyping by isoelectric focusing.

Three common alleles determine six apolipoprotein E (apo E) phenotypes that are associated with variations in serum cholesterol in the population. This genetic variation results from single nucleotide alterations at two DNA loci encoding the amino acid residues 112 and 158 of apo E. We compared results of apo E phenotyping carried out by isoelectric focusing with those of apo E genotyping accomplished by direct DNA analysis. In the latter, the target DNA was amplified by the polymerase chain reaction (PCR) and subsequently analyzed by digestion with the restriction enzyme Hha I, followed by polyacrylamide gel electrophoresis of the cleavage products. With one exception, these two techniques yielded similar results from all 40 samples tested. In addition, a rare variant form of apo E (phenotype E1) was analyzed separately and incorrectly diagnosed as E2 by the Hha I digestion method; the anticipated mutation in the codon 127 was, however, confirmed by demonstration of a new Taq I restriction site in this variant gene. These data confirm that the common isoforms of apo E usually arise from genetic variation of the codons 112 and 158 and demonstrate the feasibility of the PCR technique in apo E genotyping.

Adolescent↗
PubMed1990

Use of polymerase chain reaction to detect heterozygous familial hypercholesterolemia.

We used a modification of the polymerase chain reaction (PCR), involving two pairs of oligonucleotide primers, to detect a mutation in the low-density lipoprotein (LDL) receptor gene, commonly occurring among patients with familial hypercholesterolemia (FH) in Finland. This mutation, called FH-Helsinki, involves a large (about 9500 base pairs, bp) deletion in the LDL receptor gene extending from intron 15 to exon 18. For the PCR, one pair of primers was designed to cover both sides of the deletion in its immediate vicinity. In the presence of the deletion, the primers were brought close enough to each other to allow the amplification and electrophoretic detection of a 300-bp amplification product. In the absence of the deletion, no amplification occurred and this band accordingly was not visible in the gel. To render the interpretation of the results unequivocal, we designed a second pair of oligonucleotide primers. This pair of primers allowed another amplification product (158 bp) to appear in samples containing a normal exon 17, i.e., in DNA specimens from healthy subjects and FH heterozygotes with or without the FH-Helsinki deletion. The technique is easy to perform, avoids the use of radioactive reagents, and is applicable to the detection of any extensive DNA deletion.

Base Sequence↗
PubMed1989

Direct sequencing of affinity-captured amplified human DNA application to the detection of apolipoprotein E polymorphism.

We describe a method for the direct sequencing of DNA amplified by the polymerase chain reaction (PCR). Biotin is introduced into one strand of the amplified DNA using a 5'-biotinylated PCR primer. The synthesized fragment is captured on an avidin-matrix and rendered single stranded, whereafter the nucleotide sequence of the immobilized strand is determined by the chain termination method. The method involves few and simple operations and is thus applicable to the analysis of human genes for routine diagnostic purposes. Here we applied the method for determination of the three-allelic polymorphism of the apolipoprotein E (apo E) gene. We were able to correctly identify the alleles in both homozygous and heterozygous samples.

Affinity Labels↗
PubMed1989

Response of the beta-adrenergic system to maximal dynamic exercise in congestive heart failure secondary to idiopathic dilated cardiomyopathy.

In congestive heart failure (CHF), prolonged exposure to high plasma catecholamine levels may reduce the responsiveness of the adrenergic system to physiologic stimuli. In healthy subjects, exercise is known to induce a rapid up-regulation of lymphocytic beta adrenoceptors. Lymphocytic beta-adrenoceptor density, lymphocytic basal and isoproterenol-stimulated cyclic adenosine monophosphate (cAMP) response, plasma catecholamine concentrations and plasma cAMP levels were studied during maximal ergometer exercise in 11 patients with CHF secondary to dilated cardiomyopathy and in 6 healthy control subjects. At rest, there was no difference in the lymphocytic beta-adrenoceptor levels between the patients and control subjects (48 +/- 3 vs 42 +/- 5 fmol/mg protein, respectively). However, the exercise-induced increase in lymphocytic beta adrenoceptors was attenuated in patients when compared with controls (26 +/- 6 fmol/mg protein [56%] vs 75 +/- 16 fmol/mg protein [204%], respectively, p less than 0.02). A subgroup of 4 patients with the lowest exercise capacity (peak oxygen uptake less than 12.5 ml/min/kg) had even more reduced up-regulation compared with the other 7 patients (13 +/- 1 fmol/mg protein [29%] vs 34 +/- 9 fmol/mg protein [71%], p less than 0.05). The lymphocytic cAMP response at rest and during exercise tended to be lower in patients compared with controls, but the differences did not reach statistical significance. The plasma levels of epinephrine and norepinephrine at rest were higher in patients compared with controls, but no difference was found in the exercise values. The plasma levels of cAMP correlated closely with plasma catecholamine levels at rest, but not during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Genetic polymorphism of the apolipoprotein B gene locus influences serum LDL cholesterol level in familial hypercholesterolemia.

An XbaI restriction fragment length polymorphism (RFLP) within the coding region of the apolipoprotein B (apoB) gene has been found to be associated with serum cholesterol and triglyceride levels in several populations. Mutations in another genetic locus, the low density lipoprotein (LDL) receptor gene, give rise to familial hypercholesterolemia (FH), a disease characterized by hypercholesterolemia, tendon xanthomas and atherosclerosis. We determined the XbaI genotypes and serum lipoprotein levels of 120 unrelated patients with the heterozygous form of FH. A non-parametric analysis of variance showed a significant association between elevated serum total cholesterol concentration (P less than 0.05), serum LDL-cholesterol concentration (P less than 0.025) and the presence of the XbaI restriction site (X2 allele). Thus, patients homozygous for the presence of the XbaI restriction site (genotype X2X2, n = 28) had on average a 14% higher serum total cholesterol level and a 21% higher serum LDL-cholesterol level than those homozygous for the absence of this site (genotype X1X1, n = 29); patients heterozygous for the XbaI restriction site (genotype X1X2, n = 63) had intermediate serum total and LDL-cholesterol levels. No significant differences were seen in serum triglyceride or high-density lipoprotein (HDL)-cholesterol values between these patient groups. These data demonstrate that genetic polymorphism of the principal ligand for the LDL receptor, apoB, may contribute to serum cholesterol regulation, even in patients with grossly distorted cholesterol homeostasis.

Adult↗