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Biomedical subjects

A Holmén

Publications and source records attributed to A Holmén.

At least 19 recordsLinked to original sources
PubMed2002

Birthplace and social characteristics as risk factors for acute myocardial infarction in the province of Halland, Sweden.

The aim of the study was to explore the impact of birthplace and socio-economic characteristics on the risk of acute myocardial infarction (AMI) in a rural Swedish province. A case control study was performed and cases were all patients 30-72-y-old treated for the first time for an AMI during 1980-1992 and identified in a computerised hospital register. Three controls for each case were randomly selected from the national population register and were matched for gender, age and municipality. Birthplace ie within or outside the province, and a variety of socio-economic background factors were determined for cases and controls. The study comprised a total of 18 948 individuals including cases and controls. Altogether 4737 cases of AMI were identified whereof 3514 were men. Being born in the province was associated with the lowest risk for AMI in both sexes (RR=0.62, CI 0.57-0.67 for men and RR=0.61, CI 0.53-0.69 for women). A substantially reduced risk for men was found in farmers. In both sexes, high socio-economic status had a favourable effect on the risk to suffer an AMI. Being born in the province carried the lowest risk for AMI in both sexes and was independent of other tested socio-economic factors (income, education, occupation, and civil status). Province characteristics might be associated with this protective factor. Alternatively, migration as such might include unfavourable exposures that increase the risk for AMI among those who had moved to the province.

Adult↗
PubMed2000

Thermodynamics of sequence-specific binding of PNA to DNA.

For further characterization of the hybridization properties of peptide nucleic acids (PNAs), the thermodynamics of hybridization of mixed sequence PNA-DNA duplexes have been studied. We have characterized the binding of PNA to DNA in terms of binding affinity (perfectly matched duplexes) and sequence specificity of binding (singly mismatched duplexes) using mainly absorption hypochromicity melting curves and isothermal titration calorimetry. For perfectly sequence-matched duplexes of varying lengths (6-20 bp), the average free energy of binding (DeltaG degrees ) was determined to be -6.5+/-0.3 kJ mol(-1) bp(-1), corresponding to a microscopic binding constant of about 14 M(-1) bp(-1). A variety of single mismatches were introduced in 9- and 12-mer PNA-DNA duplexes. Melting temperatures (T(m)) of 9- and 12-mer PNA-DNA duplexes with a single mismatch dropped typically 15-20 degrees C relative to that of the perfectly matched sequence with a corresponding free energy penalty of about 15 kJ mol(-1) bp(-1). The average cost of a single mismatch is therefore estimated to be on the order of or larger than the gain of two matched base pairs, resulting in an apparent binding constant of only 0.02 M(-1) per mismatch. The impact of a mismatch was found to be dependent on the neighboring base pairs. To a first approximation, increasing the stability of the surrounding region, i.e., the distribution of A.T and G.C base pairs, decreases the effect of the introduced mismatch.

Base Pair Mismatch↗
PubMed2000

Soft tissue response to clinically contaminated and thereafter cleaned titanium surfaces. An experimental study in the rat.

The aim of the present study was to evaluate the soft tissue response to intra-orally exposed and contaminated titanium surfaces (machined, blasted or polished) after being chemically and/or mechanically cleaned. Eight adult Sprague-Dawley rats were used for histomorphometrical and histological analyses. A total of 44 experimental abutments (26 tests and 18 controls) were inserted into abdominal skinpockets of the rats for 6 weeks. No differences regarding the soft tissue response between the different surface characteristics analysed and between test and control could be observed.

Abdomen↗
PubMed1998

Hybridization of peptide nucleic acid.

The thermodynamics of hybridization and the conformations of decameric mixed purine-pyrimidine sequence PNA/PNA, PNA/DNA, and DNA/DNA duplexes have been studied using fluorescence energy transfer (FET), absorption hypochromicity (ABS), isothermal titration calorimetry (ITC), and circular dichroism (CD) techniques. The interchromophoric distances determined in the FET experiments on fluorescein- and rhodamine-labeled duplexes indicate that the solution structures of the duplexes are extended helices in agreement with available NMR (PNA/DNA) and crystal X-ray data (PNA/PNA). The melting thermodynamics of the duplexes was studied with both FET and ABS. The thermodynamic parameters obtained with ABS are in good agreement with the parameters from calorimetric measurements while FET detection of duplex melting gives in most cases more favorable free energies of hybridization. This discrepancy between FET and ABS detection is ascribed to the conjugated dyes which affect the stability of the duplexes substantially. Especially, the dianionic fluorescein attached via a flexible linker either to PNA or to DNA seems to be involved in an attractive interaction with the opposite dicationic lysine when hybridized to a PNA strand. This interaction leads to an increased thermal stability as manifested as a 3-4 degreesC increase of the melting temperature. For the PNA/DNA duplex where fluorescein is attached to the PNA strand, a large destabilization (DeltaTm = -12 degreesC) occurs relative to the unlabeled duplex, probably originating from electrostatic repulsion between the fluorescein and the negatively charged DNA backbone. In the case of the PNA/PNA duplex, the sense of helicity of the duplex is reversed upon conjugation of fluorescein via a flexible linker arm, but not when the fluorescein is attached without a linker to the PNA.

Circular Dichroism↗
PubMed1998

Micronuclei in lymphocyte subsets in relation to immune proteins and allergic disease.

This is an investigation of 54 boys and 23 girls with a median age of 19 years (range 18-22 years). The study group contained 12 boys and five girls with asthma and 23 boys and seven girls with allergic rhinitis. Sensitivity to pollen and furred animals were reported by 22 boys and eight girls and by 17 boys and six girls, respectively. The levels of serum immune proteins (IgA, IgE and IgG with subclasses, and IgM) were determined by immunological techniques. As a biomarker of chromosomal damages, the lymphocyte micronuclei was used. We analyzed the frequencies of micronuclei in 3000 B-lymphocytes and in equal numbers of T4- and T8-lymphocytes. The lymphocytes were separated by magnetic attraction in T4 (CD4), T8 (CD8) and B (CD19) fractions using Dynabeads(R). The most interesting finding of this investigation was that the three markers of atopic disease, asthma, hypersensitivity to pollen and IgE levels, associated significantly with increased frequencies of micronuclei in B-lymphocytes. There was also a relation between IgA and the frequency of micronuclei in B-cells. In an epidemiological study of 7000 individuals with allergic diseases, we have found an over-risk for lymphomas in the group with positive skin prick test. Hypothetically, we think that there may be a link between our present finding of an increased mutagenic activity and the lymphoma over-risk among individuals with allergic disease since most lymphomas stem from B-lymphocytes.

Antigens, CD↗
PubMed1998

Long-term effects of a change from a mixed diet to a lacto-vegetarian diet on human urinary and faecal mutagenic activity.

This is an investigation of the long-term effects of a shift from a mixed diet to a lacto-vegetarian diet and of a return to a mixed diet on the mutagenic activity in urine and faeces. The participants were 20 normal weight, non-smoking subjects. Dietary surveys and urinary and faecal samples were collected before and 3, 6 and 12 months after the dietary shift as well as 3 years after termination of the lacto-vegetarian diet period. The faecal samples were assayed for direct acting mutagens with the fluctuation test for weak mutagens and the urinary samples were assayed with the same assay but with a metabolic activation system, the so-called S9 fraction. The dietary data showed an increase in consumption of fruits, vegetables and dairy products and a decrease in meat, fish, eggs, sweets and biscuits during the vegetarian diet period. These changes led to an increase in total carbohydrates, fibre, vitamin C and calcium and a decrease in fat and protein intake. Mutagenic activity in both urine and faeces decreased after shift to the vegetarian diet and mutagenic activity in faeces increased when the volunteers returned to a mixed diet (P = 0.025 and 0.035 respectively when comparing the diets). These data indicate that dietary factors may effect mutagenic activity in urine and faeces. However, it is still not clear whether a decrease in animal products, a change in other nutritional factors or a decrease in frying are the main contributors to this change.

Adult↗
PubMed1997

Frequency of patients with acute asthma in relation to ozone, nitrogen dioxide, other pollutants of ambient air and meteorological observations.

OBJECTIVE: To study the association of the daily frequency of registration of patients with acute asthma at the emergency department of a central hospital in the south-west of Sweden with levels of air pollution and meteorological observations. METHODS: A retrospective longitudinal study was made of asthma patients taken from a hospital registry. This information was correlated with measurements of ozone, nitrogen dioxide, sulphur dioxide, toluene, temperature and relative humidity. Patients were from the catchment area of the Central Hospital of Halmstad containing around 120,000 inhabitants. A total of 4127 visits of patients with acute asthma to the emergency department at the Central Hospital of Halmstad were registered during a period of 1247 days from January 1990 to May 1993. The differential optical absorption spectroscopy (DOAS) technique was used to monitor levels of air pollutants over a distance of 1000 m in the central part of the town of Halmstad. Data on temperature, relative humidity, precipitation, wind speed and wind direction for the time period were supplied by the Swedish Meteorological and Hydrological Institute (SMHI). RESULTS: There were many statistically significant correlations between the levels of air pollutants and the meteorological measurements and a strong negative correlation between ozone and nitrogen dioxide. There was a statistically significant effect on asthma visits in children of low temperature and high nitrogen dioxide levels, and on asthma visits in adults of high temperature and high levels of ozone. CONCLUSIONS: There was a different reaction pattern in children and adults with asthma regarding temperature and ozone/nitrogen dioxide. The strong correlations between temperature and air pollution and between the levels of ozone and nitrogen dioxide made the true relation between asthma, air pollution and temperature hard to evaluate statistically.

Acute Disease↗
PubMed1997

Dietary influence on some proposed risk factors for colon cancer: fecal and urinary mutagenic activity and the activity of some intestinal bacterial enzymes.

This investigation studied the effects of a shift from a well-balanced mixed diet to a lacto-vegetarian diet on the mutagenic activity in urine and feces and on some cancer-associated bacterial enzymes in human feces (beta-glucuronidase, beta-glucosidase, and sulphatase). Three months after the shift to the lacto-vegetarian diet, there was a significant decrease in mutagenic activity in urine and feces, beta-glucuronidase, beta-glucosidase, and sulphatase per gram feces wet weight. In contrast, the fecal mutagenic activity and the enzyme activities remained unchanged if expressed per daily output. However, the urinary mutagenic activity expressed as total daily output decreased. Part of the explanation for the decreased fecal mutagenic activity and the decreased enzyme activities is obviously a dilution effect, because much of the increased fecal weight after the shift in diet was associated with a higher water content.

Adult↗
PubMed1996

Acute glomerulonephritis, Henoch-Schönlein purpura and dental amalgam in Swedish children: a case-control study.

The issue of adverse health effects from dental amalgam and the concurrent low-dose exposure to inorganic mercury have been scrutinized by several Swedish expert groups during the past years. Only rarely have amalgam fillings in children been related to health effects. Experimental studies in genetically disposed animals have shown that low doses of inorganic mercury can induce autoimmune glomerulonephritis. The present case-control study included 31 children with acute glomerulonephritis and 33 with Henoch-Schönlein purpura retrieved from an in-patient register for the period 1973-1992 at the county hospital in Halmstad, Sweden. The median age was 10 and 9 years, respectively, for the two diagnostic groups. Dental clinics reported amalgam burden of the patients during the year before the date of diagnosis. Corresponding data were obtained for three randomly selected controls for each case, drawn from the case records of the same dental clinics, with matching for age and sex. Odds ratios (95% confidence interval) were 1.42 (0.49, 4.11) for Henoch-Schönlein purpura, 0.59 (0.25, 1.38) for acute glomerulonephritis and 0.84 (0.40, 1.75) for both diseases combined. The results of this study did not indicate increased disease risk in relation to amalgam burden.

Adolescent↗
PubMed1995

Increased frequencies of micronuclei in T8 lymphocytes of smokers.

Micronucleus frequencies and mitotic indices were analyzed in B, T4, and T8 lymphocytes from 40 smokers and 42 non-smoking referents. The highest level of micronuclei was found in T4 cells followed by T8 and B cells. These differences were statistically significant. There were statistically significant linear correlations between the micronucleus frequencies of all three subsets. There was a statistically significant effect of smoking only in the T8 cells. Smoking also increased the number of neutrophilic granulocytes and lymphocytes in the peripheral blood. There was a statistically significant effect of age on the micronucleus frequencies in T4 and T8 lymphocytes. The mitotic indices did not have any effect on the micronucleus frequencies and they were not influenced by smoking, age or sex.

Adult↗
PubMed1995

A prospective study of cancer incidence in a cohort examined for allergy.

In order to assess the association between atopy and cancer risk, a cohort of 6593 skin-prick-tested patients was established. Among atopic subjects, no overall increased cancer risk was found, but the incidence of both breast cancer (standardized incidence ratio (SIR) 2.50, 95% CI 1.01-5.16) and malignant lymphomas (SIR 4.40, 95% CI 1.20-11.3) was significantly enhanced. Atopic subjects with asthma showed a decreased overall cancer risk (SIR 0.73, 95% CI 0.27-1.60), as compared with the other asthmatic subjects (SIR 1.46, 95% CI 1.03-2.04). The cancer risk for subjects with rhinitis was near unity (SIR 1.11), irrespective of whether the subjects were atopic or not. An almost significant risk increase for cancer was observed among subjects with urticaria (SIR 1.70, 95% CI 0.99-2.80). Our results support neither the original hypothesis of an overall cancer protective effect of atopy, nor that of an opposite effect; rather, they strengthen the view that the association between atopic diseases and cancer is complex.

Adolescent↗
PubMed1994

Does transurethral resection of a clinically benign prostate gland increase the risk of developing clinical prostate cancer? A 10-year follow-up study.

BACKGROUND: Theoretical considerations have raised the suspicion that transurethral resection of the prostate (TURP) may increase the risk of developing prostate cancer in clinically benign prostate glands. Previous studies have not shown an increased risk among men who had undergone TURP for benign prostatic hyperplasia compared with the risk in age-matched control subjects. However, in all of these studies, all men with stage T1 prostate cancer in the TURP-group were excluded, possibly creating a bias, because no similar exclusion could be made for the controls. METHODS: The incidence and mortality of clinical prostate cancer were studied in 198 patients who had TURP and in 203 age-matched male control subjects. In both groups, all patients with known prostate cancer and patients with suspected cancer by digital rectal examination were excluded from the study. However, patients with stage T1 cancer found by the TURP were included in the comparison between the groups. RESULTS: The mean age in the two groups was 67 +/- 6 years. The patients were followed for an average of 10.2 +/- 1.2 years and 10.4 +/- 1.8 years in the TURP group and the control group, respectively. Clinical prostate cancer developed in six patients who had TURP and subsequently in five control (odds ratio, 0.8 [0.2-3.1]; P < 0.97). Before follow-up, three men in each group died because of prostate cancer (odds ratio, 1.3 (0.24-7.45); P < 0.97). CONCLUSIONS: The results of this study suggest that neither benign prostatic hyperplasia nor TURP increased the risk of developing clinical prostate cancer over the next 10 years in patients with a benign prostate gland determined by rectal examination before TURP.

Aged↗
PubMed1994

Micronuclei and mitotic index in B-, T4- and T8-cells treated with mitomycin C and gamma-irradiation.

Lymphocytes were treated in vitro with mitomycin C and gamma-radiation at different doses (0-250 nmol/l and 0-2 Gy, respectively). After incubation in RPMI 1640 medium and stimulation with phytohemagglutinin for 72 h, the lymphocyte subgroups T4 (CD4), T8 (CD8) and B (CD19) were separated by an immunomagnetic method and analyzed for the presence of micronuclei. With mitomycin C the highest levels were found in T4- and B-cells. When micronuclei were induced by irradiation the T4-cells showed the highest frequencies and the B-cells the lowest. The outcome of B-cells with gamma-irradiation was probably due to a pronounced cytotoxic reaction in this cell type, which could be measured as a decrease in mitotic index.

B-Lymphocytes↗
PubMed1994

Effect of acid precipitation on retention and excretion of elements in man.

From a population of 8918 farmers, 237 were selected whose consumption of locally produced foods was high. The subjects' water sources, private wells, were of different degrees of acidity. Significant associations between pH (median 6.7, range 4.7-8.6) of the drinking water and element concentrations were found. The correlation was negative for aluminium (Al; median 0.07 mumol/l), cadmium (Cd; 0.44 nmol/l), copper (Cu; 0.24 mumol/l) and lead (Pb; 1.9 nmol/l), and positive for calcium (Ca; 0.62 mmol/l) and magnesium (Mg; 0.21 mmol/l). Associations could not be found between the pH of, or element concentrations in, the water and concentrations of A1 (0.17 mumol/l), Mg (0.86 mmol/l) and selenium (Se; 1.0 mumol/l) in plasma, Cd (2.0 nmol/l), Pb (0.19 mumol/l) and mercury (Hg; 13 nmol/l) in blood, or A1 (12 mumol/mol creatinine) and Cu (11 mumol/mol creatinine) in urine. The concentrations of Hg in blood and Se in plasma were related to fish consumption, Cd and Pb in blood to smoking, A1 in urine to antacid intake, Pb in blood to rifle activities and hunting, and Hg in blood to hunting. Acid precipitation has an effect on element concentrations in drinking water, but not on the retention of those elements in the subjects investigated.

Acid Rain↗
PubMed1994

Increased frequency of micronuclei in lymphocytes of Swedish chimney sweeps.

Forty-five Swedish chimney sweeps and 49 controls were investigated with micronuclei stimulated by phytohemagglutinin and pokeweed mitogen and by analysis of lymphocyte subgroups and neutrophilic leukocytes. There was a statistically significant effect among sweeps with respect to both micronuclei variables and neutrophilic leukocytes. The effect on lymphocyte micronuclei was most prominent in pokeweed mitogen-stimulated cells, which may imply that the T4 lymphocytes were preferentially damaged by the occupational exposure.

Adolescent↗
PubMed1993

Micronucleus induction in human B and T lymphocytes separated by an immunomagnetic technique.

Micronuclei were induced in human lymphocytes by mitomycin C or gamma radiation. After the incubation the cells were separated in B- and T-cells by an immunomagnetic method, i.e., Dynabeads. The cultures were stimulated by PHA. The effect of different incubation times (60-110 h) as well as different doses of mitomycin C (0-100 nmol/l) and gamma radiation (0-2 Gy) at an incubation time of 72 h were studied. There were significantly higher frequencies of micronuclei in B- than in T-cells, when micronuclei were induced by mitomycin C. This was not found with gamma radiation, probably because of a cytotoxic effect of this agent on the B-cells.

B-Lymphocytes↗