Biomedical subjects

Stefan Hansen

Publications and source records attributed to Stefan Hansen.

5 recordsLinked to original sources

PubMed2006

Cognitive deficits and CTG repeat expansion size in classical myotonic dystrophy type 1 (DM1).

BACKGROUND: This study was designed to investigate cognitive abilities and their correlations with CTG repeat expansion size in classical Myotonic dystrophy type 1 (DM1), given that earlier studies have indicated cognitive deficits, possibly correlating with blood CTG repeats expansion size. METHODS: A measurement of CTG repeat expansion in lymphocytes and an extensive neuropsychological examination was made in 47 patients (25 women and 22 men). Individual results in the examination were compared with normative data. RESULTS: A substantial proportion of patients with DM1 (> 40%) scored worse in comparison to normative collectives on tests measuring executive, arithmetic, attention, speed and visuospatial abilities. We found significant correlations between longer CTG repeat expansion size and lower results on most tests associated with these abilities. Furthermore, the association between executive (frontal) deficits and DM1 were strengthened when considering both test results and correlations with CTG repeat expansion size in lymphocytes. CONCLUSION: This study showed deficits in several cognitive abilities when patients with DM1 are compared to normative collectives. Some of the neuropsychological tests associated with these abilities are correlated to CTG repeat expansion size in blood. These data highlight the importance of considering cognitive deficits when seeing patients with classical DM1 in clinical practice, but also the utility of using blood CTG repeat expansion size as a broad predictor of finding cognitive deficit in DM1.

Journal Article↗

PubMed2005

Executive function and memory in posttraumatic stress disorder: a study of Bosnian war veterans.

The present study assessed neuropsychological functions related to attention, executive function and everyday memory in a group of men with a diagnosis of combat-related posttraumatic stress disorder (PTSD). Twenty Bosnian male combat veterans with a diagnosis of PTSD were tested using the Sustained Attention to Response Task, the Hayling Sentence Completion Test, the Trail Making Test, Rivermead Behavioral Memory Test and Wechsler Adult Intelligence Scale (verbal scales). Their performance was compared with age- and IQ-matched male war veterans with no PTSD. The study disclosed pervasive cognitive impairments with large effect sizes pertaining to attention, working memory, executive function, and memory. The effects did not appear to be attributable to alcohol abuse, loss of consciousness, or educational level. We speculate that, in the present group of combat veterans, PTSD was associated with dysfunction of a higher-level attentional resource which in turn affected the activity in other systems concerned with memory and thought.

Adult↗

PubMed2005

Temperamental development in the rat: the first year.

Behavioral continuity and change was studied in 32 (16 male) Wistar rats observed in the hole board and canopy tests, considered to measure exploration and anxiety, respectively. Subjects were tested at 6, 11, 16, 21, 37, and 52 weeks of age. In comparison to 16-week-old rats (the standard age of rats in many experiments), juveniles seemed more anxious and exploratory, whereas mature rats were more anxious and less exploratory. There was substantial behavioral consistency between week 6 and 52, the correlations being especially high between weeks 11 and 52. Principal components analyses revealed one temperamental dimension reflecting harm avoidance in juvenile and mature rats, whereas adult rats were characterized by a further dimension, reflecting novelty seeking.

Age Factors↗

PubMed2002

Interaction of spiral ganglion neuron processes with alloplastic materials in vitro(1).

The cochlear implant (CI) involves the introduction of alloplastic materials into the cochlea. While current implants interact with cochlear neurons at a distance, direct interactions between spiral ganglion (SG) neurites and implants could be fostered by appropriate treatment with neurotrophic factors. The interactions of fibroblasts and osteoblasts with alloplastic materials have been well studied in vitro and in vivo. However, interactions of inner ear neurons with such alloplastic materials have yet to be described. To investigate survival and growth behavior of SG neurons on different materials, SG explants from post-natal day 5 rat SG were cultured for 72 h in the presence of neurotrophin-3 (10 ng/ml) on titanium, gold, stainless steel, platinum, silicone and plastic surfaces that had been coated with laminin and poly-L-lysine. Neurite outgrowth was investigated after immunohistological staining for neurofilament, by image analysis to determine neurite extension and directional changes. Neurite morphology and adhesion to the alloplastic material were also evaluated by scanning electron microscopy (SEM). On titanium, SG neurites reached the highest extent of outgrowth, with an average length of 662 microm and a mean of 31 neurites per explant, compared to 568 microm and 21 neurites on gold, 574 microm and 24 neurites on stainless steel, 509 microm and 16 neurites on platinum, 281 microm and 12 neurites on silicone and 483 microm and 31 neurites on plastic. SEM revealed details of adhesion of neurites and interaction with non-neuronal cells. The results of this study indicate that the growth of SG neurons in vitro is strongly influenced by alloplastic materials, with titanium exhibiting the highest degree of biocompatibility with respect to neurite extension. The knowledge of neurite interaction with different alloplastic materials is of clinical interest, as development in CI technology leads to closer contact of implanted electrodes with surviving inner ear neurons.

Animals↗

PubMedDate not supplied

Novelty seeking and harm avoidance in relation to alcohol drinking in intact rats and following axon-sparing lesions to the amygdala and ventral striatum.

Our previous research has pointed to a behavioural pattern in rats similar to the one seen in the prototypic Type 2 alcoholic, where male rats bearing basal forebrain excitotoxin axon-sparing lesions show an increased alcohol intake, lowered responsiveness to threat (harm avoidance) and an enhanced tendency to exploring novel surroundings (novelty seeking). The purpose of the present study was to: (1) examine whether excessive alcohol-consuming rats have a diminished response to potential danger and an enhanced tendency to explore novel surroundings; (2) investigate a possible relationship between the above-mentioned behavioural parameters and two of the emotional motor systems in the basal forebrain, i.e. the extended amygdala and the ventral striato-pallidal system. Thus, we compared the effect of ibotenic axon-sparing lesions (3.5 microg/0.35 microl) to the temporal part of the amygdala with lesions in the ventral striatum on alcohol intake, harm avoidance (stretched attend postures) and novelty seeking (nose pokes), before and after surgery. Our results suggest that: (1) intact animals high in novelty seeking drink more alcohol than rats low on this trait; (2) lesions of the amygdala decrease harm avoidance and fluid intake, especially in animals showing above-average levels of risk assessment pre-operatively; (3) neuronal loss in the ventral striatum stimulates novelty seeking and alcohol intake, particularly in rats which initially show less novelty seeking than average.

Alcohol Drinking↗