Light adaptation of cones in rabbits and guinea pigs

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: During light adaptation of the retina, cone electroretinograms (ERGs) can be obtained. It is known that during light adaptation considerable changes occur in the cone ERGs of man, monkeys and mice. All these species have vascular retinae. In the present study we examined whether the same applies to mammalian species with a limited retinal vasculature (rabbits) or avascular retinae (guinea pigs), and which both have two types of cones but scotopic ERGs with completely different morphology. Material and methods: ERGs were recorded from anaesthetized rabbits and guinea pigs with corneal electrodes made from steal wire. Copper wire placed in the mouth of the animal served as reference electrode, and a subcutaneous needle as ground. Recordings were amplified 1000-fold, with bandwidth settings at 1-1000 Hz, and fed into a computer via an A/D converter. Corneas were anaesthetized with a topical application of proparacaine, and pupils dilated with topical application of tropicamide. ERGs were elicited with brief (10 msec) light flashes, and the retina light adapted with a steady white background light. Results: The scotopic b-wave is more than twice the amplitude of the a-wave in rabbits, while the scotopic b-wave in guinea pigs is only slightly larger than the a-wave. The b-wave of the cone ERG is twice the amplitude of the cone a-wave in both species. Once a background light has been turned on, the amplitude increases in both species and the process of light adaptation reaches a peak about 10 minutes thereafter. The b-wave implicit time is shortened by light adaptation in rabbits, but not in guinea pigs. Oscillatory potentials are present in guinea pig ERGs when recorded in dark but not when recorded in light. Conclusions: Mammals that have avascular retinae and which are without long-wavelength cones show evidence of light adaptation of the cone ERG. In guinea pigs the cone ERG increases in amplitude during light adaptation without concomitant shortening of the implicit time. These changes occur at similar rate in rabbits and guinea pigs. The oscillatory potentials in rabbits increase in amplitude but not in guinea pigs. These results suggest that different mechanisms determine the light adaptation of the cone ERG in guinea pigs than in rabbits.Tilgangur: Þegar sjónhimna er aðlöguð að ljósi er hægt að skrá sjónhimnurit (electroretinogram, ERG) keilna. Vitað er að við ljósaðlögun verða miklar breytingar í sjónhimnuriti keilna hjá mönnum, öpum og músum. Þessar tegundir hafa æðar í sjónhimnu. Í þessari rannsókn var athugað hvort sama eigi við um tegundir spendýra með lítið af æðum í sjónu (kanínur) eða engar (marsvín) æðar í sjónu og sem hafa tvær tegundir keilna en alls ólík sjónhimnurit í rökkri. Efniviður og aðferðir: Sjónhimnurit voru skráð frá svæfðum kanínum og marsvínum með skráningarskautum úr stálvír, sem staðsett voru á hornhimnu augans. Koparvír staðsettur í munni var notaður sem viðmiðunarskaut og nál undir húð sem jarðtenging. Skráning var mögnuð 1000-falt, með bandvídd 1-1000 Hz, og niðurstöður fluttar í tölvu með A/D breytikorti. Hornhimna var staðdeyfð með próparakaíni, sjáaldur víkkað með trópikamíð dropum. Sjónhimnurit var vakið með stuttum (10msek) ljósblikkum, og sjónhimna aðlöguð að stöðugu hvítu bakgrunnsljósi. Niðurstöður: Í rökkri er b-bylgja meir en helmingi stærri en a-bylgja í sjónhimnuriti kanína, en b-bylgja aðeins eilítið stærri en a-bylgja hjá marsvínum. Í sjónhimnuriti keilna er hins vegar b-bylgja helmingi stærri en a-bylgja hjá báðum tegundum. Eftir að kveikt er á bakgrunnsljósi eftir aðlögun að rökkri hækkar spenna svara og nær hámarki eftir um 10 mínútur í báðum tegundum. Dvöl b-bylgju styttist hjá kanínum, en ekki hjá marsvínum. Í sjónhimnuriti keilna hjá kanínum eru sveifluspennur (oscillatory potentials), sem stækka að spennu við aðlögun að ljósi. Sveifluspennur eru í sjónhimnuriti marsvína, þegar það er skráð í rökkri, en engar í sjónhimnuriti keilna. Ályktanir: Spendýr með æðalausa sjónhimnu og engar langbylgjukeilur sýna ljósaðlögun sjónhimnurits keilna. Í marsvínum eykst sjónhimnurit keilna að spennu án þess að dvöl breytist við ljósaðlögun. Þessar breytingar eru svipaðar í tíma í kanínum og marsvínum. Sveifluspennur aukast að spennu í kanínum en ekki marsvínum. Niðurstöður benda til að önnur ferli ráði ljósaðlögun sjónhimnurits keilna hjá marsvínum en kanínum

Transcranial magnetic stimulation

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenTranscranial Magnetic Stimulation (TMS) is a new non-invasive method to investigate the central nervous system. Initially it was used to assess the functional integrity of the pyramidal pathways but more recently various other aspects of brain function have been studied including cortical excitability. By localised interference with brain function, it is possible to use TMS to assess the relationship between various brain regions and cognitive functions. The therapeutic effect of TMS has been explored in the treatment of neurological diseases and psychiatric disorders such as epilepsy, cerebellar ataxia and depressive illness.Segulörvun heila í gegnum höfuðkúpu er notuð til rannsókna á miðtaugakerfi. Upphaflega var þessi aðferð þróuð til að meta starfsemi og ástand hreyfitauga­brauta milli heila og mænu, en er nú einnig notuð til margvíslegra rannsókna á heilastarfsemi. Meta má hömlunar- og örvunarástand heilabarkar sem getur breyst vegna heilasjúkdóma og við lyfjagjöf. Með staðbundinni truflun á starfsemi taugafrumna eftir segulörvun hefur verið hægt að kanna tengsl milli heilasvæða og hugrænna ferla. Í ljós hefur komið möguleg notkun segulörvunar í meðferð taugasjúkdóma og geðraskana. Rannsóknir hvað þetta varðar hafa meðal annars beinst að flogaveiki, mænu- og hnykilhrörnun og djúpri geðlægð

Care-Seeking Pattern among Persons with Depression and Anxiety: A Population-Based Study in Sweden

Background. In primary care, a vast majority of patients affected with depression and anxiety present with somatic symptoms. Detection rate of psychiatric symptoms is low, and knowledge of factors influencing care seeking in persons affected by depressive and anxiety disorders on a population level is limited. Objective. This study aims to describe if persons, affected by depression and anxiety disorders, seek care and which type of care they seek as well as factors associated with care seeking. Method. Data derives from a longitudinal population-based study of mental health conducted in the Stockholm County in 1998–2010 and the present study includes 8387 subjects. Definitions of anxiety and depressive disorders were made according to DSM-IV criteria, including research criteria, using validated diagnostic scales. 2026 persons (24%) fulfilled the criteria for any depressive or anxiety disorder. Results. Forty-seven percent of those affected by depression and/or anxiety had been seeking care for psychological symptoms within the last year. A major finding was that seeking care for psychological symptoms was associated with having treatment for somatic problems. Conclusions. As a general practitioner, it is of great importance to increase awareness of mild mental illness, especially among groups that might be less expected to be affected

Consequences of rape : injuries, posttraumatic stress and neuroendocrinological changes

Each year, approximately 3-4% of the Swedish female population experiences a sexual assault. Only a small percentage of these women will report the assault to the police, and even fewer will seek medical help. This thesis is based on studies on women seeking medical help at the Emergency Clinic for Raped Women at Stockholm South General Hospital, in Stockholm, Sweden, after having been sexually assaulted. The aim of the thesis was to improve the knowledge about women seeking medical help after rape, explore risk the factors for the development of PTSD, and explore the neuroendocrinological changes in PTSD patients. Study I compared intimate partner assaults to assaults by other known assailants and to assaults by strangers in terms of the use of physical violence and risk of sustaining injuries. A retrospective review of patient files and forensic examinations from the acute visits of 690 consecutive women showed that women who were sexually assaulted by their intimate partners more frequently reported physical violence (OR 4.1) than women assaulted by strangers (OR = 2.0) and acquaintances (OR = 1.0). Extragenital injuries showed a trend towards being more frequently seen after intimate partner assaults as compared to the two other groups. Genital injury prevalence was not related to the victim-assailant relationship. Study II aimed to explore the prevalence of PTSD six months after sexual assault and explore the potential risk factors for the development of PTSD. Two hundred and one women were assessed at baseline regarding mental health using self-rating questionnaires and followed up after six months with questionnaires, as well as a clinical interview for PTSD diagnosis. Thirty-nine percent of the women had developed PTSD at the six-month assessment, and 47% suffered from moderate or severe depression. The major risk factors for PTSD were having been assaulted by multiple assailants, suffering from acute stress disorder shortly after the assault, having been exposed to several acts during the assault, having been injured, having co-morbid depression, and having a history of two or more earlier traumas. Study III was conducted in order to adjust the concentrations of various endogenous steroids in Study IV for possible diurnal variation. Blood samples were taken every 4th hour during a 24-hour period in 10 premenopausal women in the follicular phase of the menstrual cycle and assessed regarding their concentrations of allopregnanolone, cortisol, cortisone, 11-deoxycortisol, progesterone, 17OH-progesterone, pregnenolone, 17OH-pregnenolone, DHEA, androstenedione, testosterone, estrone, and estradiol. The results suggested that all steroids, apart from the estrogens, had a diurnal variation in the follicular phase. All steroids, apart from allopregnanolone, had a diurnal curve similar to that of cortisol (i.e., with a peak in the morning just after awakening and the lowest concentrations during the night). Allopregnanolone had a less steep curve, with high concentrations throughout the day and a peak around noon. Study IV assessed whether concentrations of the same endogenous steroids measured in Study III in the immediate aftermath of rape could predict the development of PTSD and depression. The study design was the same as in Study II but with a blood sample added at the acute visit. Low concentrations of cortisol and the Δ5 steroids (pregnenolone, 17OH-pregnenolone, and DHEA) shortly after rape were associated with a history of earlier traumatization, and low allopregnanolone concentrations shortly after rape were associated with a psychiatric treatment history. However, there was no association between any of the steroids and pre-existing PTSD or the development of PTSD after six months. Results also suggested an association between menstrual cycle phase and the HPA axis. Study V assessed the sensitivity of the GABA-A receptor in 10 drug naïve patients with PTSD as compared to 10 healthy controls measured with saccadic eye velocity (SEV) and subjective ratings of sedation. SEV was measured after injections of the positive GABA-A receptor modulator allopregnanolone, the GABA-A receptor agonist diazepam and the GABA-A receptor antagonist flumazenil, each on separate occasions, and during the follicular phase of the menstrual cycle. The results showed that the PTSD patients were less sensitive to GABA-A-receptor-active substances, probably due to an acquired chronic tolerance to these substances caused by chronic exposure of neuroactive steroids over a long period of time. Conclusions: Sexual assaults by intimate partners are more violent and result in injuries just as often as assaults by strangers. However, physical injuries after sexual assaults are generally few and genital injuries minor. PTSD and depression, on the other hand, are common after sexual assaults, and an increased risk of developing PTSD is caused by a combination of victim vulnerability and the extent and nature of the current assault. Concentrations of endogenous steroids in the immediate aftermath of sexual assault (after having been adjusted for their diurnal variation) cannot predict the development of PTSD. However, low concentrations of several steroids are seen in previously traumatized women and in women with a psychiatric morbidity, two factors that have both been shown to increase the risk of developing PTSD. Finally, as a consequence of the reduced sensitivity of the GABA-A receptor in PTSD patients, the use of GABA-A-receptor-active compounds, such as sleeping pills, will be less useful for this group of patients

Reconstructing and understanding the impacts of storms and surges, southern North Sea

Coastal barriers are ubiquitous globally and provide a vital protective role to valuable landforms, habitats and communities located to landward. They are, however, vulnerable to extreme water levels and storm wave impacts. A detailed record of sub-annual to annual; decadal; and centennial rates of shoreline retreat in frontages characterized by both high (> 3 m) and low (< 1 m) dunes is established for a barrier island on the UK east coast. For four storms (2006–2013) we match still water levels and peak significant wave heights against shoreline change at high levels of spatial densification. The results suggest that, at least in the short-term, shoreline retreat, of typically 5–8 m, is primarily driven by individual events, separated by varying periods of barrier stasis. Over decadal timescales, significant inter-decadal changes can be seen in both barrier onshore retreat rates and in barrier extension rates alongshore. Whilst the alongshore variability in barrier migration seen in the short-term remains at the decadal scale, shoreline change at the centennial stage shows little alongshore variability between a region of barrier retreat (at 1.15 m a$^{−1}$) and one of barrier extension. A data-mining approach, synchronizing all the variables that drive shoreline change (still water level, timing of high spring tides and peak significant wave heights), is an essential requirement for validating models that predict future shoreline responses under changing sea level and storminess.This paper was completed while the first author (SB) was a recipient of a Leverhulme Research Fellowship (RF-2015-045) for a project entitled Development and Application of a shoreline response model. This paper is a contribution to NERC BESS Consortium grant A hierarchical approach to the examination of the relationship between biodiversity and ecosystem service flows across coastal margins (grant reference NE/J015423/1). Table 1 reports information gathered as part of an EU FP7 Collaborative Project (grant agreement no: 603458) Resilience-Increasing Strategies for Coasts – toolkit (http://www.risckit.eu).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/esp.390

Svensk blick på nordisk litteraturhistoria

Margareta Petersson &amp; Rikard Schönström (red.), Nordens litteratur. Lund: Student­litteratur 2017, 574 s

Throw Them All in One Pot? Differences in Stereotypes About Subgroups of Pre-Service Teachers

According to the stereotype content model, stereotypes can be described by using the dimensions competence and warmth. Compared to other professions, teaching is associated with a paternalistic stereotype consisting of high warmth and low competence. In four studies, stereotypes about different subgroups of pre-service teachers were compared. The aim was to understand sub-stereotypes better that could lead to different levels of stereotype threat and adverse behavioral tendencies. In Study 1 (N = 335), we compared stereotypes about elementary school pre-service teachers, grammar school pre-service teachers, computer science students, law students, and psychology students reported by pre-service teachers and psychology students. In contrast to nonteaching students, both groups of pre-service teachers corresponded to the paternalistic stereotype. In Study 2 (N = 243), pre-service teachers reported stereotypes about pre-service teachers for elementary schools, special education schools, comprehensive schools, vocational schools, and grammar schools. Elementary school pre-service teachers were stereotyped most paternalistically, while grammar school pre-service teachers matched the paternalistic stereotype the least. The ratings of other school types mostly fell between these extremes. In Studies 3a (N = 133, open-ended questions) and 3b (N = 308, closed-ended questions), students of various study programs compared pre-service teachers majoring in German and history (representing a non-STEM major combination) to pre-service teachers with the majors mathematics and physics (representing a STEM major combination). Pre-service teachers studying German and history were rated warmer but less competent than pre-service teachers with the majors mathematics and physics, confirmed by both methods of measuring stereotypes. In Studies 1, 3a, and 3b, ingroup favoritism in the ratings by pre-service teacher participants was tested and only found for competence in Study 1. The importance of our results and their implications for stereotype threat effects and possible interventions are discussed