Influence of the COMT Genotype on Working Memory and Brain Activity Changes During Development

Background: The Valine158Methionine (Val158Met) polymorphism of the COMT gene leads to lower enzymatic activity and higher dopamine availability in Met carriers. The Met allele is associated with better performance and reduced prefrontal cortex activation during working memory (WM) tasks in adults. Dopaminergic system changes during adolescence may lead to a reduction of basal dopamine levels, potentially affecting Met allele benefits during development. Methods: We investigated the association of COMT genotype with behavioral (n = 322) and magnetic resonance imaging data (n = 81–84) collected during performance of a visuospatial WM task and potential changes in these effects during development (reflected in age × genotype interactions). Data were collected from a cross-sectional and longitudinal typically developing sample of 6- to 20-year-olds. Results: Visuospatial WM capacity exhibited an age × genotype interaction, with a benefit of the Met allele emerging after 10 years of age. There was a parallel age × genotype interaction on WM-related activation in the right inferior frontal gyrus and intraparietal sulcus (IPS), with increases in activation with age in the Val/Val group only. Main effects of COMT genotype were also observed in the IPS, with greater gray matter volumes bilaterally and greater right IPS activation in the Val/Val group compared with the Met carriers. Conclusions: These results suggest that COMT genotype effects on WM brain activity and behavior are not static during development. The full developmental picture should be considered when trying to understand the impact of genetic polymorphisms on the mature cognition of healthy adult or psychiatric populations

Boplatsval hos solitära getingar, bin och rovsteklar

Denna undersökning gjordes för att studera solitära steklars boplatsval speciellt med avseende på spatiala mönster. Aggregat av lämpliga bohål (bibatterier) tillverkades och gjordes tillgängliga förfrilevande steklar. Resultatet visade att steklar tenderar att anlägga bon i närheten av andra stekelbon. Ingen tendens fanns att anlägga bon i centralt belägna positioner. Steklarna verkar också föredra att anlägga bon till vänster om en tänkt mittllinje på bibatterierna. Aggregation kan vara ett sätt att undgå parasitering och predation vid boplatsen. Om detta orsakade aggregationstendensen var det dock något oväntat att inte också en central tendens kunde påvisas. Att steklarna föredrog bohål i bibatteriernas vänstra del är svårt att förklara

Time trends in Swedish patch test data from 1992 to 2000. A multi-centre study based on age-adjusted and sex-adjusted results of the Swedish standard series

Allergic contact dermatitis is recognized as a public health problem and some major allergens have been subject to intervention aiming at lowering skin exposure. There is an obvious interest in evaluating the effect of such interventions. Population studies are difficult to perform and epidemiological studies based on clinical data from testing patients with contact dermatitis are common surrogates. Our objective was to gather Swedish clinical standard series test data on two occasions in order to monitor trends in sensitization rates. Consecutive patch test results from the Swedish standard series were collected from 9 centres from 1991 to 1993 and from 1999 to 2001. In total, 3680 and 3790 patients, respectively, were included. Crude, age-adjusted and age-stratified prevalence are given separately for women and men. Our top 10 allergens are much in line with newly published European test data. Significant changes among those allergens are increasing sensitization rates for Myroxylon pereirae and decreasing rates for colophony, 5-chloro-2-methyl-4-isothiazolin-3-one, Amerchol L 101 and thiuram mix. Nickel allergy is decreasing among young women. Among less common allergens, a noteworthy increase of sensitization to 4-phenylendiamine is found. In conclusion, significant trends in sensitization rates of important allergen, reflecting changes in exposure, have been found

Ultraviolett strålning och hälsa : ett kunskapsunderlag

Ultraviolet radiation and health Exposure to ultraviolet radiation can cause adverse effects on skin, eyes, and the immune system. Some effects are acute : they appear after short duration of exposure to ultraviolet radiation. Such effects are erythema, increased pigmentation, photokeratitis and photoconjunctivitis. Other effects such as elastosis and certain forms of skin cancer are regarded as irreversible and appear after chronic exposure. The acute effects and the photoageing of the skin are commonly occurring, while the more serious cancer forms are less common : but their occurrences have increased in recent years. This is considered to be at least partly attributed to an increased exposure to ultraviolet radiation. Thus, there is an obvious need to limit the total exposure to ultraviolet radiation. Internationally, ICNIRP have developed guidelines for the limitation of exposure to ultraviolet radiation. These limitations give individuals with normal sensitivity a protection against acute effects on skin and eyes, and are also thought to protect against some of the long-term effect (e.g. certain cancer forms). Several forms of malignant melanoma are, on the other hand, thought to be a result of single episodes of heavy exposure. High levels of UV radiation can occur within Swedish industry at e.g. welding and UV curing of surface coatings. The possibilities to locally measure and control these levels at a relevant cost have improved during the last decade.Ultraviolett strålning (UV) indelas vanligen i UVA, UVB och UVC. Den dos som ger upphov till en definierad skada kallas tröskeldos. Tröskeldosen plottad som funktion av våglängd benämns aktionsspektrum. Lämplig längsta expositionstid kan beräknas på basis av aktionsspektrum genom att addera de viktade doskomponenterna från varje våglängdsområde i en exponering. UV orsakar skador på lipider och proteiner i cellmembran och inne i cellen samt på DNA. UV har flera olika skadeeffekter på huden som beror på intensitet, exponeringstid och våglängdsområde (UVA eller/och UVB). UV kan skada arvsanlagen i hudens celler samt orsaka hudrodnad, brännskador, elastos (förtjockad och rynkig hy) samt godartade och elakartade former av hudcancer. En liten andel av befolkningen har hud som är abnormt känslig för UV. Hornhinnan blockerar all UV med kortare våglängd än 290 nm. Linsen filtrerar bort merparten av all UV mellan 290-400 nm. En överdos av UV mot ögat ger akut ögonlocksrodnad och svullnad och inflammatorisk reaktion i bindehinna och hornhinna som är reversibel inom 1-2 dygn. Om dosen är mycket hög uppkommer irreversibel grå starr. Långvarig exponering av ögat för UV är associerat till förändringar i bindehinnan, hornhinnan och linsen. Iakttagelser att UV-strålning har en hämmande effekt på immunsystemet har gjorts såväl i djurexperiment som i studier på människor. Solljusexponering reducerade bl a mängden cirkulerande T-lymfocyter och naturliga mördarceller i blodet hos friska kontrollpersoner. De immunhämmande effekterna av UV-strålning kan tänkas ha negativa hälsoeffekter genom att nedsätta motståndskraften för infektioner samt eventuellt främja tumöruppkomst. Det föreligger en individuell variabilitet i känslighet för immunsuppression efter UVB-bestrålning. Den skyddande effekten av solskyddskrämer mot UV-inducerad immunsuppression är fortfarande otillräckligt studerad. Tidigare ansatser att erhålla en bättre kontroll av yrkesmässig exponering för UV-strålning har försvårats av bristen på praktiskt och ekonomiskt försvarbara mätinstrument. Numera finns sådana instrument för mätning av absolutnivåer samt även olika former av billiga och tillförlitliga persondosimetrar vilket kan vara ett alternativ för övervakning av UV-exponering hos utsatta yrkesgrupper. Den i arbetslivet mest frekventa exponeringen för UV-strålning är självfallet utomhusvistelse. Vid inomhusarbete kan dock exponering för väsentligt högre nivåer av UV-strålning uppkomma vid bristande avskärmning av ljuskällan i samband med UV-härdning av akrylatlacker, elektrosvetsning och lasersvetsning. Även lysrör för medicinska UV-behandlingar och ofiltrerade halogenlampor kan medföra höga nivåer

Renal versus splenic maximum slope based perfusion CT modelling in patients with portal-hypertension

PURPOSE To assess liver perfusion-CT (P-CT) parameters derived from peak-splenic (PSE) versus peak-renal enhancement (PRE) maximum slope-based modelling in different levels of portal-venous hypertension (PVH). MATERIAL AND METHODS Twenty-four patients (16 men; mean age 68 ± 10 years) who underwent dynamic P-CT for detection of hepatocellular carcinoma (HCC) were retrospectively divided into three groups: (1) without PVH (n = 8), (2) with PVH (n = 8), (3) with PVH and thrombosis (n = 8). Time to PSE and PRE and arterial liver perfusion (ALP), portal-venous liver perfusion (PLP) and hepatic perfusion-index (HPI) of the liver and HCC derived from PSE- versus PRE-based modelling were compared between the groups. RESULTS Time to PSE was significantly longer in PVH groups 2 and 3 (P = 0.02), whereas PRE was similar in groups 1, 2 and 3 (P > 0.05). In group 1, liver and HCC perfusion parameters were similar for PSE- and PRE-based modelling (all P > 0.05), whereas significant differences were seen for PLP and HPI (liver only) in group 2 and ALP in group 3 (all P < 0.05). CONCLUSION PSE is delayed in patients with PVH, resulting in a miscalculation of PSE-based P-CT parameters. Maximum slope-based P-CT might be improved by replacing PSE with PRE-modelling, whereas the difference between PSE and PRE might serve as a non-invasive biomarker of PVH. KEY POINTS • Peak-splenic enhancement is decreased and delayed in patients with portal-venous hypertension • The maximum-slope method uses PSE to calculate arterial and portal-venous liver perfusion • Peak-renal enhancement (PRE) is insensitive to PVH and might improve perfusion modelling • The difference between PSE and PRE might serve as a non-invasive PVH biomarker

Visualization of dialysis fistula by computed tomography using time-resolved 3D volume rendering

BACKGROUND To evaluate the function of arteriovenous (AV) dialysis fistula using dynamic computed tomography (CT) and time-resolved 3-dimensional (3D) volume rendering (VR). METHODS Seven patients referred for angiographic CT examination of the AV dialysis fistula were enrolled. Twenty-four grams of iodine were administered intravenously (iomeprol 400 mg I/mL at 6 mL/sec) followed by a 50-mL saline flush. Dynamic scanning was performed for 15-24 sec. CT images were then postprocessed on a dedicated workstation creating time-resolved 3D VR images and movies. RESULTS All studies showed good image quality showing pathology in 6 of 7 patients. Unexpected findings were observed in 1 patient, aneurysm (n = 1). Radiation dose was 5 mSv. CONCLUSIONS The function of AV dialysis fistula can be visualized using dynamic CT and time-resolved 3D VR