In vivo characterization of distinct modality-specific subsets of somatosensory neurons using GCaMP

Mechanistic insights into pain pathways are essential for a rational approach to treating this vast and increasing clinical problem. Sensory neurons that respond to tissue damage (nociceptors) may evoke pain sensations and are typically classified on the basis of action potential velocity. Electrophysiological studies have suggested that most of the C-fiber nociceptors are polymodal, responding to a variety of insults. In contrast, gene deletion studies in the sensory neurons of transgenic mice have frequently resulted in modality-specific deficits. We have used an in vivo imaging approach using the genetically encoded fluorescent calcium indicator GCaMP to study the activity of dorsal root ganglion sensory neurons in live animals challenged with painful stimuli. Using this approach, we can visualize spatially distinct neuronal responses and find that >85% of responsive dorsal root ganglion neurons are modality-specific, responding to either noxious mechanical, cold, or heat stimuli. These observations are mirrored in behavioral studies of transgenic mice. For example, deleting sodium channel Nav1.8 silences mechanical- but not heat-sensing sensory neurons, consistent with behavioral deficits. In contrast, primary cultures of axotomized sensory neurons show high levels of polymodality. After intraplantar treatment with prostaglandin E2, neurons in vivo respond more intensely to noxious thermal and mechanical stimuli, and additional neurons (silent nociceptors) are unmasked. Together, these studies define polymodality as an infrequent feature of nociceptive neurons in normal animals

Medical evaluation for suspected sexual violence against girls

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesInngangur: Kynferðisofbeldi gegn börnum hefur verið falið vandamál. Læknisskoðun er æskileg til að leita áverka, útiloka sýkingar, safna réttarlæknisfræðilegum gögnum og tryggja velferð barnsins. Samantekt var gerð á framkvæmd og niðurstöðum læknisfræðilegs mats á Landspítala og í Barnahúsi. Efniviður og aðferðir: Rannsóknin var afturskyggn og lýsandi fyrir árin 2001-2010. Upplýsingum um staðlaðar skoðanir var safnað í Barnahúsi og úr læknabréfum og matsblöðum á Landspítala um aldur, kyn, biðtíma frá tilvísun að skoðun og skráð frábrigði á ytri kynfærum. Lýsingar á frábrigðum voru flokkaðar með tilliti til tengsla við kynferðisofbeldi í samræmi við læknisfræðilegt flokkunarkerfi Adams. Upplýsingar um alvarleikastig meintra kynferðisbrota fengust frá Barnahúsi. Niðurstöður: Fjöldi læknisskoðana/-mats var 224 hjá 220 stúlkum á aldrinum 1-17 ára. Í gögnum um 218 staðlaðar skoðanir hjá stúlkum voru fullnægjandi skoðanir 201 (92%). Flestar skoðanir fóru fram innan mánaðar frá tilkynningu (meðalbiðtími 28 dagar; bil 1-166). Meyjarhaftslýsingar voru í 24 tilvikum metnar sem mögulegt kynferðislegt ofbeldi, þar með talið 21 tilvik „rofins meyjarhafts“ hjá stúlku sem var ekki kynferðislega virk. Tvö kynfæravörtutilvik greindust (1%) og ein klamýdíusýking (0,5%). Hjá stúlkum sem ekki voru kynferðislega virkar voru skoðanir eðlilegar hjá 85% (165/193); 28 sýndu hugsanleg ummerki kynferðisofbeldis eða höfðu frábrigði með óljósa/umdeilda þýðingu. Efsta alvarleikastigi var lýst hjá 71 stúlku. Ályktun: Meirihluti læknisskoðananna voru hjá ókynþroska stúlkum, töldust ekki bráðatilvik, og niðurstaðan innan eðlilegra marka. Hugsanleg ummerki um kynferðisofbeldi voru hjá einni af 8. Frábrigðum frá eðlilegri skoðun var sjaldan lýst og sýkingar sjaldgæfar. Vanda þarf aðferðir og verkferla við valkvæðar og bráðar læknisskoðanir vegna gruns um kynferðisofbeldi.Introduction: Sexual violence against children is a hidden problem. Medical examination and evaluation is needed to search for possible injuries, exclude infections, procure legal evidence and ensure the child´s welfare. We assessed medical evaluations done at Landspitali University Hospital and in the Reykjavik Children's House, a specialized clinic for childhood abuse cases. Material and methods: Retrospective descriptive analysis was performed on the standardized medical examinations. Age, sex, waiting time from reported violence until examination and recorded aberrant external genitalia findings were noted, and classified by the medically-­oriented Adams system. Offence severity stages were assigned. Results: Medical examination cases numbered 224 for 220 girls aged 1-17 years. Records were available on 218 standarized examinations among girls; 201 were adequate (92%). Most were conducted within a month (medium waiting-time 28 days; range 1-166). Hymenal changes were in 24 cases possibly associated with sexual violence, including 21 in a girl not sexually active. Two girls had human papillomavirus warts (1%) and one chlamydial infection (0.5%). Medical examination was normal in 85% (165/193) of girls who were not sexually active; 24 had possibly experienced sexual violence and four results were uncertain/controversial. For 71 offence severity was serious. Conclusion: Most examinations were conducted on prepubertal girls, were not a matter of urgency and showed normal results. Possible relation to sexual violence was described for one in eight. Infections were rare. When child sexual abuse is suspected, care with methodology and procedures is needed, both for elective and acute medical examinations

Influence of shape of quantum dots on their far-infrared absorption

We investigate the effects of the shape of quantum dots on their far-infrared absorption in an external magnetic field by a model calculation. We focus our attention on dots with a parabolic confinement potential deviating from the common circular symmetry, and dots having circular doughnut shape. For a confinement where the generalized Kohn theorem does not hold we are able to interprete the results in terms of a mixture of a center-of-mass mode and collective modes reflecting an excitation of relative motion of the electrons. The calculations are performed within the time-dependent Hartree approximation and the results are compared to available experimental results.Comment: RevTeX, 16 pages with 10 postscript figures included. Submitted to Phys. Rev.

Rectangular quantum dots in high magnetic fields

We use density-functional methods to study the effects of an external magnetic field on two-dimensional quantum dots with a rectangular hard-wall confining potential. The increasing magnetic field leads to spin polarization and formation of a highly inhomogeneous maximum-density droplet at the predicted magnetic field strength. At higher fields, we find an oscillating behavior in the electron density and in the magnetization of the dot. We identify a rich variety of phenomena behind the periodicity and analyze the complicated many-electron dynamics, which is shown to be highly dependent on the shape of the quantum dot.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Magnetization of noncircular quantum dots

We calculate the magnetization of quantum dots deviating from circular symmetry for noninteracting electrons or electrons interacting according to the Hartree approximation. For few electrons the magnetization is found to depend on their number, and the shape of the dot. The magnetization is an ideal probe into the many-electron state of a quantum dot.Comment: 11 RevTeX pages with 6 included Postscript figure

Energy levels and far-infrared spectroscopy for two electrons in a semiconductor nanoring

The effects of electron-electron interaction of a two-electron nanoring on the energy levels and far-infrared (FIR) spectroscopy have been investigated based on a model calculation which is performed within the exactly numerical diagonalization. It is found that the interaction changes the energy spectra dramatically, and also shows significant influence on the FIR spectroscopy. The crossings between the lowest spin-singlet and triplet states induced by the coulomb interaction are clearly revealed. Our results are related to the experiment recently carried out by A. Lorke et al. [Phys. Rev. Lett. 84, 2223 (2000)].Comment: 17 pages, 6 figures, revised and accepted by Phys. Rev. B (Dec. 15