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Biomedical subjects

O Olafsson

Publications and source records attributed to O Olafsson.

At least 19 recordsLinked to original sources
PubMed2004

The improved survival of experimental animals fed with fish oil is suppressed by a leukotriene inhibitor.

Fish oil is believed to alter the immune response and improve survival after infections in experimental animals. This effect may be due to altered production of the leukotrienes (LT). We, therefore, performed a study in order to evaluate whether the effect of fish oil on the immune response of experimental animals is mediated through altered production of the LT. Female NMRI mice in four groups were fed with fish oil, fish oil with 5-lipoxygenase (5-LO) inhibitor (Zileuton, Abbott Laboratories, Chicago, IL, USA), corn oil or corn oil with 5-LO inhibitor. After 6 weeks, the mice were infected with Klebsiella pneumoniae and the survival was monitored. The experiment was performed twice. Analysis was performed mainly on data pooled from both experiments. The survival of the groups fed with fish oil was increased, compared to that of all the other groups and when compared to the groups fed with fish oil with 5-LO inhibitor (log-rank test) the difference was significant (P = 0.007). It has been postulated that the effect of fish oil on the immune system is mediated through altered production of LT. In our study, blocking of the production of the LT eliminated the beneficial effects of fish oil. Our results are in concord with the hypothesis that the effect of fish oil is, at least partly, mediated through altered production of LT.

Animals↗
PubMed2003

Development of immunoglobulin A in infancy and childhood.

Serum and salivary concentrations of immunoglobulin A1 (IgA1) and IgA2 were studied in 105 Icelandic children aged 0-12 years. Serum concentrations of both IgA1 and IgA2 increased slightly (P < 0.001) during childhood. The salivary IgA1/IgA2 ratio tended to decrease during the same period; this trend is less apparent when omitting the youngest children. The salivary IgA1 and IgA2 output could be high, even in children with low levels of serum IgA. Only polymeric IgA was found in whole saliva. Interestingly, in serum, most IgA1 and IgA2 were polymeric during infancy. The proportion of polymeric IgA decreased, when the concentration of IgA increased. The polymeric form of IgA might provide the infant with better protection against invading microorganisms by activation of the innate immune mechanisms.

Age Factors↗
PubMed2001

[Trends in overweight and obesity in 45-64 year old men and women in Reykjavik 1975-1994.].

OBJECTIVE: The aim of this study was to assess possible changes in the prevalence of overweight and obesity in Iceland during the last decades. Furthermore, the possible effect of dietary changes on the observed trend in obesity prevalence was evaluated. MATERIAL AND METHODS: Participants came from stages III-V in the Reykjavik Health Study and the Reykjavik part of the MONICA studies from the period 1975-1994. The age groups 45-54 years and 55-64 years were examined. Only the information from the first visit of each person was included. The body mass index (BMI) for the participants was calculated and the percentage of those subjects considered overweight and obese according to WHO standards evaluated, using 25BMI<30 kg/m(2) as the cut-off point for overweight and BMI30 kg/m(2) as the cut-off point for obesity. Also, the observed trend in obesity prevalence is compared to changes in diet that have occurred in the same period. RESULTS: The results show that the mean weight and height of both men and women have been increasing during the study period. However, weight has increased more than can be accounted for by increased height, resulting in increased BMI. At the same time, the prevalence of overweight and obesity have increased, the relative increase in obesity far exceeding the relative increase in overweight. The prevalence of obesity more than doubled in both age groups of women during the study period, according to trend analyses. At the end of the period, almost 15% (95% confidence interval (CI), 9-22%) in the younger group of women and 25% (95% CI, 17-34%) in the older group were classified as obese. In the younger group of men, the prevalence of obesity almost doubled, while the observed increase in the older group was not statistically significant, according to trend analyses. The prevalence of obesity in the final period was about 19% (95% CI, 13-27%) and 17% (95% CI, 11-25%) in the younger and older groups of men, respectively. According to the food supply statistics there have been insignificant changes in the consumption of energy nutrients during the period. CONCLUSIONS: Overweight and obesity are becoming more common among middle-aged men and women in Reykjavik, during the period 1975-1994 and the rate of increase being comparable to that observed in many Western countries. It is urgent to respond to this problem by promoting a healthier lifestyle, both with respect to diet and physical activity.

English Abstract↗
PubMed2001

[Homocysteine, folate and cobalamin in Icelandic men and women.].

OBJECTIVE: To determine reference intervals and interquartile ranges for total homocysteine (Hcy) folate and cobalamin in Icelandic men and women and to evaluate the correlation of Hcy to serum levels of the vitamins folate and cobalamin. MATERIAL AND METHODS: Blood samples were collected from 449 individuals over a period of three months, 291 men (mean age 48.3 years) and 158 women (mean age 49.8 years). Plasma Hcy was measured by a HPLC method with fluorescence detection; folate and cobalamin levels in serum were measured by an electroimmunochemical method on an ELECSYS system from Roche. RESULTS: The reference interval for Hcy, between 2.5% and 97.5% fractiles, estimated by parametric statistics, are 6.2-17.5 micromol/L for men and 4.8-14.1 micromol/L for women. Similarly the 95% reference intervals for folate and cobalamin were estimated using parametric statistics. A significant negative correlation was found between concentrations of folate and Hcy for both men and women (p<0.01) with a correlation coefficient of -0.39 and also between cobalamin and Hcy where the correlation coefficient is -0.20. CONCLUSIONS: Reference interval for Hcy from the general presumed healthy population is estimated here for the first time in Icelandic men and women and will be of value in cardiovascular risk assessments. The negative correlation between Hcy and folate and also Hcy and cobalamin, is in agreement with results from other studies and suggests that an improved vitamin status might be beneficial in lowering Hcy in a section of the population as has been suggested in numerous studies in other countries.

English Abstract↗
PubMed2000

Serum immunoglobulinD in infants and children.

Serum immunoglobulinD (IgD) concentration is usually low in healthy individuals as compared to other immunoglobulin classes. Most studies on serum IgD are concerned with serum levels in healthy adults but reference values for young children and infants are not easily available. In order to establish age specific reference values we measured IgD levels in serum of 184 healthy Icelandic children, age 0-14 years and 60 healthy blood donors age 18-63, using the ELISA technique. Special attention was paid to the youngest age groups. Results showed low IgD values in infants and young children, gradually increasing until the age of 10 but then decreasing with age. We conclude that IgD gradually increases with age in childhood as other immunoglobulin classes but later declines. These findings can be of importance in revealing the function of IgD in the immune system as well as in the diagnosis of the hyper-IgD syndrome.

Adolescent↗
PubMed1999

P.A. Schleisner: a pioneer in epidemiology.

In 1847 Schleisner (b. 1818) was sent from Copenhagen to the Vestmanna Islands in Iceland to study the epidemic of tetanus neonatorum. The neonatal mortality in those islands at that time was 600-740 per 1000 children. He built a small hospital and introduced treatment with Peru balsam of the umbilicus. Schleisner probably assumed that the infection was caused by airborne infection, contact infection or poor hygiene. The neonatal mortality fell to about 50 per 1000. Schleisner published his results in 1849. Semmelweiss published his observations in 1850 and Snow successfully fought the cholera epidemic in London in 1854. Schleisner deserves recognition as a pioneer in the field of epidemiology.

Epidemiology↗
PubMed1998

The ms2io6A37 modification of tRNA in Salmonella typhimurium regulates growth on citric acid cycle intermediates.

The modified nucleoside 2-methylthio-N-6-isopentenyl adenosine (ms2i6A) is present in position 37 (adjacent to and 3' of the anticodon) of tRNAs that read codons beginning with U except tRNA(i.v. Ser) in Escherichia coli. In Salmonella typhimurium, 2-methylthio-N-6-(cis-hydroxy)isopentenyl adenosine (ms2io6A; also referred to as 2-methylthio cis-ribozeatin) is found in tRNA, most likely in the species that have ms2i6A in E. coli. Mutants (miaE) of S. typhimurium in which ms2i6A hydroxylation is blocked are unable to grow aerobically on the dicarboxylic acids of the citric acid cycle. Such mutants have normal uptake of dicarboxylic acids and functional enzymes of the citric acid cycle and the aerobic respiratory chain. The ability of S. typhimurium to grow on succinate, fumarate, and malate is dependent on the state of modification in position 37 of those tRNAs normally having ms2io6A37 and is not due to a second cellular function of tRNA (ms2io6A37)hydroxylase, the miaE gene product. We suggest that S. typhimurium senses the hydroxylation status of the isopentenyl group of the tRNA and will grow on succinate, fumarate, or malate only if the isopentenyl group is hydroxylated.

Chromosome Mapping↗
PubMed1997

Influenza vaccination in 22 developed countries: an update to 1995.

This study expands and updates through 1995 our earlier report on influenza vaccine use in 18 developed countries. Five of the six countries with high levels of vaccine use in 1992 (> or = 130 doses/1000 population) showed little change or slight declines over the subsequent 3 years. The exception was the United States, where a new federal program for vaccination reimbursement for the elderly helped to increase vaccine distribution from 144 to 239 doses/1000 population. The six countries with medium levels of vaccine use in 1992 (76-96 doses/1000 population) increased to > or = 100 doses/1000 population by 1995. Among the six low-use countries in 1992 (< or = 65 doses/1000 population), only Finland showed substantial improvement (96 doses/1000 population) in 1995. Four new countries were added to the study. In Germany, vaccine use increased to 80 doses/1000 population in 1995, but in Ireland it remained at a low level (48 doses/1000 population). In Korea, vaccine use increased from 17 to 95 doses/ 1000 population during the period 1987-1995. In Japan, very high levels of vaccine use (approximately 280 doses/1000 population) in the early 1980s were associated with vaccination programs for school children. However, vaccine use fell precipitously when these programs were discontinued, and only 2 and 8 doses/1000 population were used in 1994 and 1995, respectively. In all 22 countries, higher levels of vaccine use were associated with vaccination reimbursement programs under national or social health insurance and were not correlated with different levels of economic development. Excluding Japan, in 1995 there was still a greater than fourfold difference between the highest and lowest levels of vaccine use among the other 21 countries in the study. Given its well established clinical effectiveness and cost-effectiveness, none of these countries has yet achieved the full benefits of its programs for influenza vaccination.

Developed Countries↗
PubMed1997

Users of antiasthma drugs in Iceland: a drug utilization study.

There has been an increasing consensus worldwide on how to treat asthma, and, simultaneously, an increase in the sales of antiasthma drugs. However, little is known about actual drug use, dosage, combinations of drugs, etc., or about the clinical characteristics of patients using these drugs. All individuals with prescriptions for antiasthma drugs, who came to Icelandic pharmacies during March 1994, were invited to participate. By means of questionnaires, the pharmacists recorded the age and gender of the patient, the specialty of the prescribing doctor, as well as the name of the drug, total amount prescribed, and dosage. The patients were asked to answer another questionnaire on their clinical diagnosis, usage of other antiasthma drugs, etc. The pharmacists registered 2,026 individuals, with 2,687 prescriptions: 1,574 for beta2-agonists, 838 for inhaled corticosteroids, 208 for theophylline, 48 for anticholinergic drugs, and 19 for cromoglycates. One thousand, three hundred and fifty one patients answered the questionnaires. The majority (67%) claimed to have asthma, 18% chronic bronchitis, 11% emphysema and 5% other diseases or symptoms. Among those aged > or = 16 yrs with asthma, 93% used beta2-agonists, 62% inhaled corticosteroids, 19% theophylline, and very few used other drugs. The most commonly used combination (57%) was beta2-agonists with inhaled corticosteroids. Thirty one per cent used beta2-agonists as monotherapy, and 5% used only inhaled corticosteroids. Theophylline was used mainly in combination with beta2-agonists and inhaled corticosteroids. In conclusion, our data suggest that two thirds of antiasthma drug users have asthma and that most are treated according to present guidelines. The use of inhaled corticosteroids, however, seems somewhat less than optimal.

Adolescent↗
PubMed1997

What is the long term value of multiphasic health screening and the initial judgement of benefit?

The long term effects of multiphasic health screening (MHS) are rarely studied. In 1964 a random sample of 546 women and 544 men born 1899, 1904, 1909, 1914 or 1919 equally distributed on cohorts from the Swedish town Eskilstuna were invited to examination. For several reasons 167 persons (15%) did not participate in the study. In 1969 the whole sample was invited to a second MHS together with a control group that had not been exposed to MHS. Furthermore, 79 of those alive 1989 born 1899 or 1904 and examined 1964 and 1969 were reexamined. Over all survival rate 1989 for those examined 1964 was for males 18% and for females 35%. Screening instruments 1964 and 1969 were questionnaires, laboratory tests, antropometric measurements, ECG, measurement of blood pressure, chest radiography, peak expiratory flow (PEF), tonometry and fundoscopy of the eyes, audiometric screening, dental, gynecological and general clinical examination. Systolic hypertension for both sexes, low PEF and smoking, low cholesterol in women were negatively related to survival. Of 18 diabetics only one was alive at follow-up. No association was found between BMI and mortality for men, but some (1964 p < 0.01; 1969 p < 0.05) for women. Altogether 87 individuals were 1969 judged to have had some benefit of the MHS in 1964, 40 of them substantial. This was, however, not statistically significantly associated with improved survival. Of the reexamined survivors 86% reported to be generally satisfied with their life situation. The prognostic value of graded benefit was analysed in some detail. The survival to age 85 in the group allotted any benefit was somewhat less good (37%) than in the group with no benefit (44%). The difference did not reach statistical significance.

Aged↗
PubMed1996

Mutation in the structural gene for release factor 1 (RF-1) of Salmonella typhimurium inhibits cell division.

A temperature-sensitive mutant of Salmonella typhimurium LT2 was isolated. At the nonpermissive temperature cell division stopped and multinucleated filaments were formed. DNA, RNA, or protein synthesis was not affected until after about two generations. Different physiological conditions, such as anaerobiosis and different growth media, suppress the division deficiency at high temperatures. Certain mutations causing a reduced polypeptide chain elongation rate also suppress the division deficiency. The mutation is recessive and shown to be in the structural gene for release factor I (prfA). DNA sequencing of both the wild-type (prfA+) and mutant (prfA101) allele revealed a GC-to-AT transition in codon 168. Like other known prfA mutants, prfA101 can suppress amber mutations. The division defect in the prfA101 mutant strain could not be suppressed by overexpression of the ftsQAZ operon. Moreover, at the nonpermissive temperature the mutant shows a normal heat shock and SOS response and has a normal ppGpp level. We conclude that the prfA101-mediated defect in cell division is not directed through any of these metabolic pathways, which are all known to affect cell division. We speculate that the altered release factor I induces aberrant synthesis of an unidentified protein(s) involved in the elaborate process of septation.

Aldehyde Oxidoreductases↗
PubMed1995

Influenza vaccination in 18 developed countries, 1980-1992.

Influenza continues to be an important cause of preventable morbidity and mortality. Although influenza vaccine is widely recommended for older high-risk individuals, no studies have compared its use in different countries. We gathered information on influenza vaccine distribution in 18 developed countries for the period 1980-1992. During the 1980s there was a > or = 10-fold difference in annual per capita vaccine distribution among these countries, and in 1992 the difference was still more than 7-fold. Several countries demonstrated large increases in vaccine use over the study period, some showing substantial increases in specific years. Thirteen of the 18 countries recommend influenza vaccination for all elderly persons and 11 countries provide reimbursement for vaccination through national or social health insurance. These countries tend to have higher levels of vaccine use. Historical, economic and political factors also affect vaccination practices and policies, but their relationships to differences in vaccine use between countries are not known. A better understanding of why the use of influenza vaccine varies among countries will be important if its protective benefits are to be fully realized.

Developing Countries↗
PubMed1994

Synthesis and function of isopentenyl adenosine derivatives in tRNA.

Isopentenyl adenosine derivatives can be found next to the anticodon (position 37) in tRNA from both the Bacteria and Eucarya domains. These modified nucleosides improve the efficiency of tRNA in translation, can increase and decrease translational fidelity, and make the tRNA less codon context sensitive. In bacteria the synthesis of isopentenyl adenosine derivatives seems to be linked to iron metabolism and central metabolic pathways.

Adenosine↗
PubMed1992

National registration of accidents in Iceland.

Community based registration of accidents has been employed in Iceland from 1987. A form developed in the emergency ward at the city Hospital of Reykjavik has been used for the registration. The following issues have been registered: the type and the seriousness of the injury, treatment, place of accident and time of accident. Health centres in Iceland have been computerized from 1976. At the time being about half of the health centres participate in the registration with the information included in the form as the source. Every health center has its well defined district. The accidents among the inhabitants in each district is registered, while accidents among other people, e.g. tourists, is registered separately. At this moment 183,000 out of a total number of 259,000 inhabitants are covered by the registration, i.e. 71% of the population. In 1989 the frequency of accidents was 198 per 100,000 inhabitants. 26% of the accidents occurred at home, 11% at work, 9% during physical activity, 6% was traffic accidents, whereas the same proportion occurred at school. This registration system has been created as a result of annual conferences on accidents arranged by the Director General of public health since 1984. Representatives for the following parties have been invited; medical doctors working in hospitals and health centres, clinical nurses, physiotherapists, the National Insurance Service, other insurance companies, rescue and ambulance personal, fire departments, the Automobile Association, the communication Council. Local communities members of the parliament, voluntary organizations, e.g. Red Cross, the Sea Rescue Service and the Aviation Board. This activity has stimulated measures aiming at preventing accidents in several local communities.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents↗
PubMed1991

Structure of TGF-beta 1-induced human immunoglobulin C alpha 1 and C alpha 2 germ-line transcripts.

We have characterized the structure of the human immunoglobulin C alpha 1 and C alpha 2 germ-line transcripts that are synthesized upon treatment of human B lymphocytes with Branhamella catarrhalis (a B cell mitogen) and transforming growth factor beta 1 (TGF-beta 1). These transcripts initiate upstream of the switch alpha 1 and switch alpha 2 regions and contain, together with the C alpha 1 and C alpha 2 sequences, additional exons designated according to the generally accepted nomenclature I alpha 1 and I alpha 2 respectively. The I alpha exons are spliced directly onto the acceptor splice site of the CH1 domains of the C alpha 1 and C alpha 2 genes. As in other previously characterized germ-line transcripts, stop codons present in all three reading frames prevent translation of the C alpha 1 and C alpha 2 heavy-chain coding sequences. The longest open reading frame (ORF) present in the I exons can code for a polypeptide of only 26 amino acids. The human I alpha exons do not show any significant sequence homology with the corresponding mouse I alpha exon. However, comparison of nucleotide sequences of the genomic mouse and human I alpha regions demonstrated the presence of an approximately 300 bp highly conserved element located immediately upstream of the transcription initiation sites of the human and mouse C alpha germ-line transcripts. The isolation of the C alpha 1 and C alpha 2 germ-line transcripts will further facilitate the characterization of the molecular events responsible for the regulation of the human C alpha heavy chain loci.

Base Sequence↗