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Biomedical subjects

M Olsson

Publications and source records attributed to M Olsson.

At least 37 records · Page 2Linked to original sources
PubMed2002

Variation in heritability of tadpole growth: an experimental analysis.

Heritability characteristically shows large variation between traits, among populations and species, and through time. One of the reasons for this is its dependence on gene frequencies and how these are altered by selection and drift through the evolutionary process. We studied variation in heritability of tadpole growth rate in populations of the Swedish common frog, Rana temporaria. In populations evolving under warmer conditions, we have demonstrated elsewhere that tadpoles show better growth and physiological performance at relatively higher temperatures than tadpoles with an evolutionary history in a relatively cooler part of the distribution range. In the current study, we ask whether this process of divergence under natural selection has influenced the genetic architecture as visualised in estimates of heritability of growth rate at different temperature treatments under laboratory conditions. The results suggest that the additive genetic variance varies between treatments and is highest in a treatment that is common to both populations. Our estimates of narrow sense heritability are generally higher in the thermal regime that dominates in the natural environment. The reason for this appears not primarily to be because the component of additive genetic variation is higher in relation to the total phenotypic variation under these conditions, but because the part of the phenotypic variance explained by environmental variation increases at temperatures to which the current populations has been less frequently under selection.

Animals↗
PubMed2002

Acquired platelet dysfunction may be an aetiologic factor in Heyde's syndrome--normalization of bleeding time after aortic valve replacement.

BACKGROUND: There is a well-documented relationship, with unknown aetiology, between aortic valve stenosis and occult gastrointestinal bleeding in elderly patients. Despite several studies attempting to determine the prevalence and to discuss the aetiology, there are still many unanswered questions. METHODS: A total of 288 consecutive patients with valvular aortic stenosis--mean age 73 +/- 9 years aortic stenosis group (ASG)--were compared with 129 pacemaker-treated patients, mean age 73 +/- 9 years control group (CG). Screening for occult blood in stools was performed in both groups. Those with a positive Hemocult test or a history of gastrointestinal bleeding were scheduled for further examination including upper endoscopy and colonoscopy. Template bleeding time was performed on patients in both groups and in patients with a prolonged bleeding time with an extended coagulation evaluation was carried out. Patients referred to aortic valve replacement and with a preoperatively prolonged bleeding time were re-examined after surgery. RESULTS: There was a significant difference in the number of subjects with prolonged bleeding time between groups (ASG 19; CG 2; P = 0.028). Re-examination of the bleeding time after aortic valve surgery revealed normalized values in nine of 12 (P = 0.0003). The number of patients with positive Hemocult test did not differ between groups (ASG 29; CG 12; NS). Comparison of the pressure gradient over the aortic valve demonstrated a significantly higher maximal gradient amongst patients with a preoperatively prolonged bleeding time (113 mm HG vs. 90 mmHG; P = 0.005). CONCLUSION: Prolonged bleeding time is related to valvular aortic stenosis and seems to be caused by acquired platelet dysfunction. The normalization of the bleeding time after valve surgery supports the hypothesis that the calcified cusps may interact with the platelet function.

Aged↗
PubMed2002

Socioeconomic environmental factors and hospitalization for acute bronchiolitis during infancy.

UNLABELLED: Bronchiolitis is a major cause of hospitalization during infancy. The aim of this study was to evaluate the influence of socioeconomic factors on the hospitalization of infants with bronchiolitis. All infants below 1 y of age living in the city of Malmö, Sweden, and hospitalized at the University Hospital. Malmö, owing to bronchiolitis during the years 1998 and 1999 were identified. The bronchiolitis hospitalization rates (BHRs) were determined for the infants living in each of the 10 different administrative residential areas of Malmö and correlated with socioeconomic factors (percentage of immigrants, per capita income, unemployment rate and households receiving social benefit) in the respective residential areas. The severity of the disease on admission and during hospital care was assessed by comparing oxygen saturation, days with supplemental oxygen and length of stay. BHR varied more than fourfold between the 10 residential areas. BHR varied significantly with per capita income and the percentage of immigrants. Infants living in the area with the highest social burden were hospitalized almost twice as often as those from the rest of the city, but the severity of disease was similar. CONCLUSION: The association between socioeconomic factors and hospitalization indicates that these factors may have a significant influence on the hospitalization rate in bronchiolitis during infancy.

Acute Disease↗
PubMed2001

Fluorescence correlation spectroscopy detects galanin receptor diversity on insulinoma cells.

Fluorescence correlation spectroscopy (FCS) allows the study of interactions of fluorescently labeled ligand with receptors in living cells at single-molecule detection sensitivity. From the autocorrelation functions of fluorescence intensity fluctuations, the diffusion time of molecules through the confocal volume is analyzed, and from that, the molecular weights of free and bound molecules can be calculated. We have applied FCS to study the receptor diversity for the neuropeptide galanin (GAL) in cultured cells. FCS measurement of the fluorophore rhodamine-labeled GAL (Rh-GAL) has been performed in 0.2-fL confocal volume elements of the laser beam. The analysis of autocorrelation functions of Rh-GAL in solution above cells and at cell membranes demonstrates that the diffusion time of unbound Rh-GAL is 0.16 ms, whereas diffusion times of membrane-bound Rh-GAL are 22 and 700 ms. Because both of the diffusion times (22 and 700 ms) are much longer as compared to that of unbound Rh-GAL, they correspond to slow-diffusing complexes when Rh-GAL is bound to the cell membranes. Addition of excess nonlabeled GAL is accompanied by competitive displacement. Full saturation of the GAL binding is obtained at nanomolar concentrations. Scatchard analysis of binding data reveal one binding process, assuming one binding site per Rh-GAL (n = 1). On the other hand, the appearance of two diffusion times, 22 and 700 ms, suggests the existence of two subpopulations of GAL receptor complexes or two subtypes of GAL receptor not detected before. This makes an important point that FCS permits the identification of receptors, which were not possible to detect before by conventional binding techniques. The inhibitory effect of pertussis toxin on the GAL binding considers a G-protein-involved allosteric system, important for the clarification of essential steps in the G-protein-related signal transduction. This study is of pharmaceutical significance, since it will provide insights into how FCS can be used as a rapid technique for studying ligand-receptor interactions in living cells, which is one step forward for large-scale drug screening in cell cultures.

Animals↗
PubMed2001

Different domains in the third intracellular loop of the GLP-1 receptor are responsible for Galpha(s) and Galpha(i)/Galpha(o) activation.

It has previously been shown that the GLP-1 receptor is primarily coupled to the adenylate cyclase pathway via activation of Galpha(s) proteins. Recent studies have shown that the third intracellular loop of the receptor is important in the stimulation of cAMP production. We have studied the effect of three synthetic peptide sequences derived from the third intracellular loop of the GLP-1 receptor on signal transduction in Rin m5F cell membranes. The whole third intracellular loop strongly stimulates both pertussis toxin and cholera toxin-sensitive G proteins, while the N-terminal half exclusively stimulates cholera toxin-sensitive G proteins and the C-terminal half only stimulates pertussis toxin-sensitive G-proteins as demonstrated by measurements of GTPase activity. These data confirm that the principal stimulatory G-protein interaction site resides in the third intracellular loop, but also suggest that the GLP-1 receptor is not only coupled to the Galpha(s) but also to the Galpha(i)/Galpha(o) type of G proteins and that distinct domains within the third intracellular loop are responsible for the activation of the different G-protein subfamilies.

Adenylate Cyclase Toxin↗
PubMed2001

Laparoscopy reduces unnecessary appendicectomies and improves diagnosis in fertile women. A randomized study.

BACKGROUND: The aim of this study was to study the value of diagnostic laparoscopy prospectively in fertile women scheduled for acute appendectomy. METHODS: For this study, 110 women, with acute abdominal pain ages 15 to 47 years, in whom the surgeon had decided to perform an appendectomy, were randomized to either open appendectomy or diagnostic laparoscopy, then open appendectomy if necessary. RESULTS: Appendicitis was diagnosed in 66% of the women after open surgery, and in 73% after laparoscopy. During laparoscopy, was appendicitis misdiagnosed in only 7% of the women, from whom the appendix unnecessarily removed, whereas 34% in the open surgery group had a healthy appendix removed. No appendicitis was missed in the laparoscopic group. The relative risk of removing a healthy appendix in open surgery was 6.6 relative risk (range, 2-21 C.I.) as compared with laparoscopy. Among the women with a healthy appendix, a gynecologic diagnosis was found in 73% after laparoscopy, as compared with 17% after open surgery. CONCLUSIONS: Laparoscopy reduces unnecessary appendectomies and improves diagnosis in fertile women.

Adolescent↗
PubMed2001

The otter (Lutra lutra) in Sweden--population trends in relation to sigma DDT and total PCB concentrations during 1968-99.

Polychlorinated biphenyl (PCB) has been suggested as the major cause of the European otter (Lutra lutra) population decline. This study investigates temporal and geographical changes in otter numbers as well as total PCB and sigma DDT concentrations in otters and their food in different parts of Sweden with various pollution impacts during three decades. In Sweden, rare species belong to the State and carcasses of such specimens are sent to the authorities. Two-hundred and eight specimens have been used to investigate temporal and spatial variation in the otter populations during 1968 and 1999. One-hundred and twenty-five of them have been chemically analysed. The population trends in northern Sweden coincide with the temporal trends of the contaminants. When concentrations of PCBs decrease in the environment, otter population increases. Neither aldrin/dieldrin nor mercury pollution seem to explain why the Swedish otter populations decreased dramatically during the 1960s-1980s. In southern Sweden total PCB concentrations are still high and the indications of improvement of the population are weak.

Animals↗
PubMed2001

The serotonin reuptake inhibitor fluoxetine reduces sex steroid-related aggression in female rats: an animal model of premenstrual irritability?

The aggressive behavior displayed by some (but not all) female Wistar rats when an unfamiliar rat is being introduced into their home cage (the resident intruder paradigm) was found to be higher in non-receptive phases (metestrus, diestrus) than in the receptive phases (proestrus, estrus) of the estrus cycle, and effectively reduced by ovariectomy. When removal of the ovaries was followed by administration of estradiol and progesterone, in a regimen mimicking the normal cyclical release of these hormones, aggressive behavior was elicited, two days after estrus, in animals that had displayed aggressive behavior before ovariectomy, but not in those that had not. Short-term administration of a serotonin reuptake inhibitor (fluoxetine hydrochloride; 10 mg/kg, i.p.; 4-5 days) reduced both the aggressive behavior displayed during the diestrus phase by normally cycling rats, and the aggressive behavior elicited by administration of estradiol plus progesterone after ovariectomy. It is suggested that the aggressive behavior displayed by the female Wistar rat in the resident intruder paradigm may serve as an animal model of premenstrual dysphoria.

Aggression↗
PubMed2001

Clinical significance of nested polymerase chain reaction and immunofluorescence for detection of Pneumocystis carinii pneumonia.

OBJECTIVE: To study the clinical significance of a nested polymerase chain reaction (PCR) method compared to immunofluorescence (IF) for detection of Pneumocystis carinii. METHODS: The medical records of 89 patients with 91 episodes of pneumonia were scrutinised retrospectively. The pneumonia episodes were divided into categories according to the likelihood that the patient had had clinical Pneumocystis carinii pneumonia (PCP). All respiratory tract samples from the 89 patients (34 broncho-alveolar lavage (BAL) and 57 sputa) were tested for Pneumocystis carinii by IF and nested PCR. RESULTS: Fifteen episodes, as diagnosed by IF, were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 60%, specificity 97%). Among the P. carinii DNA-positive episodes, detected with nested PCR, 24 were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 96%, specificity 59%), since all IF-positive samples were nested PCR positive. Only one pneumonia episode classified as a probable PCP, was negative with both methods, as applied to a BAL sample. CONCLUSIONS: IF applied to BAL or sputum seems to be the most specific method for diagnosis of clinical PCP. Additional clinical cases can be found by nested PCR, although this then gives a high risk of detecting subclinical colonisation of P. carinii.

Adolescent↗
PubMed2001

Frequent use of the hospital emergency department is indicative of high use of other health care services.

STUDY OBJECTIVE: We sought to determine the proportion of emergency department patients who frequently use the ED and to compare their frequency of use of other health care services at non-ED sites. METHODS: A computerized patient database covering all ambulatory visits and hospital admissions at all care facilities in the county of Stockholm, Sweden, was used. Frequent ED patients were defined as those making 4 or more visits in a 12-month period. RESULTS: Frequent users comprised 4% of total ED patients, accounting for 18% of the ED visits. The ED was the only source of ambulatory care for 13% of frequent versus 27% of rare ED users (1 ED visit). Primary care visits were made by 72% of frequent ED users versus 57% by rare ED visitors. The corresponding figures for hospital admission were 80% and 36%, respectively. Frequent ED visitors were also more likely to use other care facilities repeatedly: their odds ratio (adjusted for age and sex) was 3.43 (95% confidence interval [CI] 3.10 to 3.78) for 5 or more primary care visits and 29.98 (95% CI 26.33 to 34.15) for 5 or more hospital admissions. In addition, heavy users had an elevated mortality (standardized mortality ratio 1.55; 95% CI 1.26 to 1.90). CONCLUSION: High ED use patients are also high users of other health care services, presumably because they are sicker than average. A further indication of serious ill health is their higher than expected mortality. This knowledge might be helpful for care providers in their endeavors to find appropriate ways of meeting the needs of this vulnerable patient category.

Adolescent↗
PubMed2001

Genotypes of clustered cases of Pneumocystis carinii pneumonia.

Reports of outbreaks of Pneumocystis carinii pneumonia (PCP) among human immunodeficiency virus-negative immunocompromised patients have suggested a person-to-person transmission of P. carinii. In this study, 17 bronchoalveolar lavage isolates from patients in 3 PCP outbreaks were genotyped, 2 in renal transplant recipients and 1 outbreak among patients with haematological disorders. Genotypes in the P. carinii sp. f. hominis (P. carinii f.sp. hominis) mt large subunit ribosomal RNA site 85 were detected by 2 methods: direct sequencing and 3 different allele-specific polymerase chain reaction assays. Although limited data on patient contacts were available, the detected P. c. hominis genotypes do not support person-to-person transmission as the predominant transmission route of P. carinii in humans.

Adult↗
PubMed2001

Repeated use of the emergency department: qualitative study of the patient's perspective.

OBJECTIVE: To explore what lies behind repeated emergency department (ED) use, from the patients' own perspectives. METHODS: Qualitative study based on in depth interviews with frequent users of the ED at the Huddinge University Hospital, Sweden. Ten adult patients having visited the ED 6-17 times in the previous 12 months were interviewed. The personal meaning they attached to the symptoms and their encounters at the ED were inductively analysed, thereby relating patient behaviour to life conditions. RESULTS: The frequent ED visitors perceive pain or other symptoms as a threat to life or to personal autonomy. Irrespective of whether or not the patients relate their health problems to a traumatic event, overwhelming anxiety compels them to seek urgent help. Clear cut diagnoses are seldom mentioned. Although none of the patients is homeless or totally lacking in means, the narratives reveal struggles with adverse life circumstances and medical, psychological and/or social problems, including alcohol or other substance misuse. Occasional referrals from the ED to a psychiatrist seem not to lead to any continuous treatment or to a change in the patients' health seeking behaviour. Satisfaction with care becomes adversely affected when the patients perceive that the ED staff classifies their use of the ED as inappropriate or when their symptoms are belittled. CONCLUSIONS: From their own perspectives, frequent ED visitors are in need of urgent care. It is particularly important to these patients that the personal meaning they attach to their symptoms is attended to and respected by the ED staff.

Adult↗
PubMed2000

Testosterone, ticks and travels: a test of the immunocompetence-handicap hypothesis in free-ranging male sand lizards.

The immunocompetence-handicap hypothesis suggests that androgen-dependent male characters constitute honest signals of mate and/or rival quality because of the imposed costs through immune suppression associated with elevated testosterone levels. We demonstrate in a field experiment that male sand lizards (Lacerta agilis) exposed to elevated testosterone suffered from increased mass loss and tick load compared to control males. Although the first of these two results could be due to an elevated basal metabolic rate from increased plasma testosterone levels, the increased parasite load was statistically independent of the loss in body condition and is likely to be due to compromised immune function. Testosterone-treated males showed greater mobility than control males, and greater mobility resulted in higher mating success. Our experiment thus lends support to the immunocompetence-handicap hypothesis, suggesting that male testosterone levels have been moderated by balancing selection for reproductive success and sustained immune function.

Animals↗
PubMed2000

[Atrial septal defect--catheter-based closure now feasible!].

Atrial septal defects (ASD) of hemodynamic significance are usually treated surgically in early childhood. However, many cases will not be detected until the patient has become an adult. As there is a risk of development of pulmonary hypertension and tachyarrythmia in hemodynamically significant defects, closure is necessary. Although surgery is considered a safe procedure with very low perioperative mortality, there is a risk of complications and prolonged hospitalization, and postoperative convalescence is two months. Today we are able to offer patients with ASD of the secundum type an alternative treatment using catheter technique. The devices used are self expanding and easy to deploy, with a high success rate and low complication rate. Post-procedural convalescence is two days.

Cardiac Catheterization↗
PubMed2000

Differential expression of mouse laminin gamma2 and gamma2* chain transcripts.

Laminins are large heterotrimeric basement membrane proteins that consist of alpha, beta, and gamma chains. We have previously shown that the human gamma2 and gamma2* transcripts result from the alternative use of the LAMC2 gene 3'-end exons. To explore the biological significance of the alternative gamma2 transcripts, we isolated the cDNA coding for the mouse laminin gamma2* transcript, characterized the 3'-end of the murine LAMC2 gene, and studied the expression of alternative gamma2 transcripts in several mouse tissues. The sequence reported here is the first one containing a full-length gamma2* 3'-UTR from any species. The mouse gamma2* transcript is 4110 bases and encodes a putative polypeptide of 1110 amino acids. This polypeptide lacks the C-terminal cysteine residue thought to be important for heterotrimer formation. The mouse gamma2* transcript was found to be expressed in several tissues by polymerase chain reaction (PCR), but at very low levels. The clearest signals were obtained on embryonic day 7, and in heart and testis of adult tissues. When the laminin gamma2* transcript expression pattern was compared with that of the gamma2 chain, a similar tissue distribution was observed. There was, however, a significant difference in expression levels. The longer gamma2 transcript was found to be much more abundant than the shorter gamma2* variant. Moreover, by whole-mount in situ hybridization, the shorter gamma2* form was localized in the mesenchyme of the developing kidney whereas the longer gamma2 form was exclusively present in the epithelium of the Wolffian (nephric) duct and ureteric bud. The results indicate different functions for the gamma2 variants.

Alternative Splicing↗