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Biomedical subjects

I Keller

Publications and source records attributed to I Keller.

At least 19 recordsLinked to original sources
PubMed2006

Repetitive optokinetic stimulation induces lasting recovery from visual neglect.

PURPOSE: To evaluate whether repetitive optokinetic stimulation with active pursuit eye movements leads to substantial and greater recovery from visual neglect as compared to conventional visual scanning training. METHODS: Two groups of five patients with leftsided hemineglect were consecutively collected and matched for clinical and demographic variables as well as neglect severity. One group received five treatment sessions of repetitive optokinetic stimulation (R-OKS) within one week, while the other group received the same amount of conventional visual scanning training (VST) using identical visual stimuli and setup. All patients were treated in a single-subject baseline design with treatment-free intervals before (14 days) and after specific neglect therapy (14 days). Dependent variables were the improvements in digit cancellation, visuoperceptual and visuomotor line bisection and visual size distortion during treatment. The transfer of treatment effects was assessed by a paragraph reading test. RESULTS: The results showed superior effects of OKS treatment in all five patients which generalized across all tasks administered and remained stable at follow-up. In contrast, no significant improvements were obtained after VST training in any of these tasks, except in line bisection. CONCLUSION: We conclude that the presentation of moving visual stimulus displays with active smooth pursuit eye movements can be more efficient than conventional visual scanning training using static visual displays.

Adult↗
PubMed2005

Visuospatial neglect in near and far space: dissociation between line bisection and letter cancellation.

The differential performance on a line bisection and a cancellation task in near and far space was studied. A group of 10 patients with severe left-sided visuospatial neglect and a group of 10 right-brain damaged patients without neglect were examined. The stimuli were presented at a distance of 60 cm (near space) and 160 cm (far space), respectively, and corrected for visual angle. In the line bisection task, patients were asked to point to the estimated line centre with a pencil (near space) or a stick (far space). In the cancellation task, patients pointed to all target stimuli they could detect using either a pencil (near space) or a stick (far space). Most patients with left hemineglect showed a more prominent neglect in far space as compared to near space for the line bisection task, whereas no difference of performance between near and far space was found in the control patients. In contrast, no group showed a distance effect in the cancellation task. The observation that only line bisection is influenced by the distance of the stimulus suggests that line bisection and cancellation are processed differentially. It is proposed that line bisection requires an allocentric reference system focusing attention on objects, whereas cancellation tasks are based on an egocentric reference system responsible for visuospatial attention. Our results indicate that distance changes perception within the allocentric but not within the egocentric system.

Adult↗
PubMed2005

Estimation of effective population size and detection of a recent population decline coinciding with habitat fragmentation in a ground beetle.

We assess the impact of habitat fragmentation on the effective size (N(e)) of local populations of the flightless ground beetle Carabus violaceus in a small (<25 ha) and a large (>80 ha) forest fragment separated by a highway. N(e) was estimated based on the temporal variation of allele frequencies at 13 microsatellite loci using two different methods. In the smaller fragment, N(e) estimates ranged between 59 and a few hundred, whereas values between 190 and positive infinity were estimated for the larger fragment. In both samples, we detected a signal of population decline, which was stronger in the small fragment. The estimated time of onset of this N(e) reduction was consistent with the hypothesis that recent road constructions have divided a continuous population into several isolated subpopulations. In the small fragment, N(e) of the local population may be so small that its long-term persistence is endangered.

Animals↗
PubMed2005

A case of stunning of lung and bone metastases of papillary thyroid cancer after a therapeutic dose (3.7 GBq) of 131I and review of the literature: implications for sequential treatments.

Thyroid stunning is usually defined as the inhibition or suppression of iodide trapping by remnant thyroid tissue or by functioning metastases following a diagnostic dose of 131I. The risk of stunning increases progressively with larger doses. Because the threshold above which this effect occurs in thyroid remnants seems to be between 37 MBq and 111 MBq of 131I, therapeutic 131I doses of 3.7 GBq may cause stunning. We describe stunning of papillary thyroid cancer lung and bone metastases after a therapeutic dose of 131I (3.7 GBq). A T1 bone metastasis and bilateral lung metastases were diagnosed by post-therapeutic dose whole-body scan. Nuclear MRI detected another lesion at T4, whose 131I fixation was not obvious. An additional 0.7 GBq were given after recombinant TSH, 37 days after the therapeutic dose; 24 h later, uptake by the lung and T1 metastases had disappeared, but trapping was again seen 6 months later on the post-therapeutic scan. This re-appearance is evidence in favour of the transitory and reversible character of stunning, and confirms its correspondence to the decreased ability of viable thyroid cells to trap iodine and not to their destruction. A better understanding of stunning would make it possible, in the event of rapidly progressing disease and in conjunction with recombinant thyroid stimulating hormone (TSH), to give several therapeutic doses of 131I in close succession without each dose hampering the effectiveness of the subsequent one.

Adolescent↗
PubMed2004

[Primary prevention of non-communicable diseases. Experiences from population based intervention in Finland for the global work of WHO].

Globally most people die from noncommunicable diseases. Especially in developing countries noncommunicable diseases are on the rise, effecting especially poorer societal segments. The noncommunicable diseases contribute greatly to societal and economic losses and inequities in health status. The North Karelia Project was started in Finland to prevent noncommunicable diseases and with the main aim to curb the high mortality from cardiovascular diseases. In collaboration with the community, the health sector, the food industry and mass media, initiatives were started to promote a healthy diet, physical activity and reduce smoking. Over the last 25 years, the age adjusted mortality rate among men of 25-64 years of age from cardiovascular diseases fell by 73%, from lung cancer by 71% and total mortality fell 49%. Each country should plan and implement its own prevention programs, but lessons can be learned from the North Karelia Project. The paper discusses some key lessons and recommendation from the project for countries and for global work. In the last few years WHO has started to up-grade its work to fight noncommunicable diseases. Some initiatives are presented and discussed.

Adult↗
PubMed2004

Recent habitat fragmentation due to roads can lead to significant genetic differentiation in an abundant flightless ground beetle.

Although habitat fragmentation is suspected to pose a major threat to biodiversity, its impact on abundant invertebrate species has been little investigated. We assessed the genetic population structure of the flightless ground beetle Abax parallelepipedus in a forest fragmented by two main roads and a highway using five microsatellite loci. We detected low levels of genetic differentiation, which was concordant with the high population densities of 632-1707 individuals/ha estimated with a mark-recapture method. A Mantel test detected a highly significant increase of pairwise F(ST)-values with the number of roads between sampling locations. As expected, the most pronounced effect of the isolation due to roads was observed in the sample from the smallest fragment (highway exit loop), which was differentiated significantly from most other locations. However, no signs of a recent bottleneck or a loss of genetic variability were detected in this population, indicating a still relatively large effective population size (N(e)). Computer simulations confirmed that the observed F(ST)-values were indeed compatible with a N(e) of a few hundred individuals in this fragment, assuming strong or absolute isolation since the construction of the roads. We discuss the implications of our findings for the conservation of abundant but poorly dispersing species in fragmented habitats.

Analysis of Variance↗
PubMed2002

Neck muscle vibration induces lasting recovery in spatial neglect.

OBJECTIVES: To evaluate whether neck muscle vibration is an effective technique for neglect rehabilitation, with lasting beneficial effects. METHODS: The effects of differential treatment of visual exploration training alone or in combination with neck muscle vibration were evaluated in a crossover study of two matched groups of 10 patients suffering from left sided neglect. Each group received a sequence of 15 consecutive sessions of exploration training and combined treatment. The effects of treatment were assessed with respect to different aspects of the neglect disorder such as impaired perception of the egocentric midline, exploration deficits in visual and tactile modes, and visual size distortion. The transfer of treatment effects to activities of daily living was examined by a reading test and a questionnaire of neglect related everyday problems. All variables were measured six times: three baseline measurements, two post-treatment measurements, and one follow up after two months. RESULTS: The results showed superior effects of combination treatment. A specific and lasting reduction in the symptoms of neglect was achieved in the visual mode, which transferred to the tactile mode with a concomitant improvement in activities of daily living. The improvement was evident two months after the completion of treatment. In contrast, isolated exploration training resulted in only minor therapeutic benefits in visual exploration without any significant transfer effects to other tasks. CONCLUSIONS: Neck muscle vibration is a decisive factor in the rehabilitation of spatial neglect and induces lasting recovery when given as a supplement to conventional exploration training.

Activities of Daily Living↗
PubMed2001

Presence for design: conveying atmosphere through video collages.

Product designers use imagery for inspiration in their creative design process. To support creativity, designers apply many tools and techniques, which often rely on their ability to be inspired by found and previously made visual material and to experience the atmosphere of the user environment. Computer tools and developments in VR offer perspectives to support this kind of imagery and presence in the design process. But currently these possibilities come at too high a technological overhead and price to be usable in the design practice. This article proposes an expressive and technically lightweight approach using the possibilities of VR and computer tools, by creating a sketchy environment using video collages. Instead of relying on highly realistic or even "hyperreal" graphics, these video collages use lessons learned from theater and cinema to get a sense of atmosphere across. Product designers can use these video collages to reexperience their observations in the environment in which a product is to be used, and to communicate this atmosphere to their colleagues and clients. For user-centered design, video collages can also provide an environmental context for concept testing with prospective user groups.

Communication↗
PubMed2001

Contrast-enhanced carotid MR angiography with commercially available triggering mechanisms and elliptic centric phase encoding.

OBJECTIVE: The technical feasibility of contrast-enhanced MR angiography of the carotid arteries was evaluated with routinely available timing sequences and elliptic centric acquisition. The image quality of the contrast-enhanced MR angiography was compared with that of multiple overlapping thin-section acquisition MR angiography (MOTSA MR angiography). SUBJECTS AND METHODS: Sixty-three patients were enrolled. A 2-mL test bolus and commercially available software were used to time the gadolinium bolus. High-resolution contrast-enhanced MR angiography was performed with elliptic centric acquisition. RESULTS: The average time of bolus arrival was 17.3 sec (range, 12-25 sec). In 60 of the 63 patients, we had excellent or good visualization of the carotid bifurcation using contrast-enhanced MR angiography with little or no venous contamination. Two observers ranked delineation of stenosis and morphology of proximal internal carotid artery and overall diagnostic confidence statistically significantly higher for contrast-enhanced MR angiography compared with MOTSA: Ulceration, length of stenosis, and slow flow distal to a critical stenosis were better depicted with contrast-enhanced MR angiography than with MOTSA: Venetian blind artifact, saturation of slow or in-plane flow, and artifactual narrowing in carotid artery kinks plagued MOTSA but were not seen on contrast-enhanced MR angiography. MOTSA was graded superior to contrast-enhanced MR angiography in nine of 120 carotid bifurcations analyzed. CONCLUSION: High-resolution carotid contrast-enhanced MR angiography is technically feasible. We found a 95% success rate using commercially available hardware and software. The image quality with carotid contrast-enhanced MR angiography has improved so that it is equal or superior to the longer MOTSA in most patients.

Adult↗
PubMed2000

Size distortion in spatial neglect.

One of the suggested theories to explain some aspects of neglect in patients with right parietal lesions is the spatial distortion hypothesis. To determine whether a distorted representation of space can account for the performance of neglect patients in visuospatial tasks we asked 27 neglect patients to compare the width of two horizontally aligned bars. The bars were presented symmetric to the body midline or either on the left or right side of egocentric space. The size comparison data are in accordance with the hypothesis of a distorted egocentric representation based on a dynamic remapping of space. The results support the idea that the abnormalities observed in the size comparison tasks are due to a distorted internal representation of the outside world. There are some hints that this distortion could be based on a dynamic mapping of space determined by the distribution of visuospatial attention.

Aged↗
PubMed2000

Comparative pharmacokinetics of ciprofloxacin, gatifloxacin, grepafloxacin, levofloxacin, trovafloxacin, and moxifloxacin after single oral administration in healthy volunteers.

In an open, randomized, six-period crossover study, the pharmacokinetics of ciprofloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, and trovafloxacin were compared after a single oral dose in 12 healthy volunteers (6 men and 6 women). The volunteers received 250 mg of ciprofloxacin, 400 mg of gatifloxacin, 600 mg of grepafloxacin, 500 mg of levofloxacin, 400 mg of moxifloxacin, and 200 mg of trovafloxacin. The concentrations of the six fluoroquinolones in serum and urine were measured by a validated high-performance liquid chromatography method. Blood and urine samples were collected before and at different time points up to 48 h after medication. Levofloxacin had the highest peak concentration (C(max), in micrograms per milliliter) (6.21+/-1.34), followed by moxifloxacin (4.34+/-1.61) and gatifloxacin (3.42+/-0.74). Elimination half-lives ranged from 12.12+/-3.93 h (grepafloxacin) to 5.37+/-0.82 h (ciprofloxacin). The total areas under the curve (AUC(tot), in microgram-hours per milliliter) for levofloxacin (44.8+/-4.4), moxifloxacin (39.3+/-5.35), and gatifloxacin (30+/-3.8) were significantly higher than that for ciprofloxacin (5.75+/-1.25). Calculated from a normalized dose of 200 mg, the highest C(max)s (in micrograms per milliliter) were observed for levofloxacin (2.48 +/-0.53), followed by moxifloxacin (2.17+/-0.81) and trovafloxacin (2.09+/-0.58). The highest AUC(tot) (in microgram-hours per milliliter) for a 200-mg dose were observed for moxifloxacin (19.7+/-2.67) and trovafloxacin (19.5+/-3.1); the lowest was observed for ciprofloxacin (4.6+/-1.0). No serious adverse event was observed during the study period. The five recently developed fluoroquinolones (gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, and trovafloxacin) showed greater bioavailability, longer half-lives, and higher C(max)s than ciprofloxacin.

Administration, Oral↗
PubMed2000

The greying world: a challenge for the twenty-first century.

As we approach the next millennium, an unprecedented rapid increase of total and relative numbers of older persons in both the developed and the developing world is being observed. The total aged population (aged more than 60 years) world-wide will rise from 605 million in the year 2000 to 1.2 billion in 2025. Population ageing is due to two factors: increased life expectancy and decreasing fertility rates. Public health interventions are major contributor to both. A significant consequence of ageing is the shift from communicable to non-communicable diseases. The World Health Organization (WHO) is addressing the multiple challenges posed by population ageing through integrated activities that include consolidation of databases, capacity building (research and training), advocacy and policy development. These are all approached through WHO perspectives on ageing and health: life-course, health promotion, socio-economic, community based, intergenerational, cultural, gender and ethical.

Aged↗
PubMed1999

Visual background motion reduces size distortion in spatial neglect.

Patients with visual neglect show deficits in horizontal size perception in their neglected hemispace, as previously reported. The present study examined whether this size distortion can be modulated by visual background motion to the left or right while the patient performs a visual size judgment task. Six neglect patients and six normal subjects were investigated with a psychophysical size judgment task. All neglect patients showed a significant perceptual underestimation of horizontal bars in their left hemispace expressed as an overestimation of horizontal object size in the baseline (no motion) condition. Slow visual motion of background stimuli towards the right, ipsilesional side aggravated the deficit slightly, but not significantly, whereas leftward background motion completely normalized the size distortion (in four cases) or even led to an overcompensation (in two cases). This facilitatory effect was specific as it was obvious for the constant errors in the size judgments, but not in their accuracy as reflected by unchanged difference thresholds. These results suggest that coherent background motion restores temporarily the disturbed perception and representation of horizontal object size in spatial neglect.

Adult↗
PubMed1999

Family, religion, and depressive symptoms in caregivers of disabled elderly.

STUDY OBJECTIVE: To explain the variations in depressive symptomatology among primary caregivers of community dwelling activities of daily living disabled elderly and to evaluate the role of family and religiosity on the mental health consequences of caregiving in Spain. DESIGN: Cross sectional study. SETTING: City of Leganés in the metropolitan area of Madrid, Spain. PARTICIPANTS: All caregivers of a representative sample of community dwelling activities of daily living disabled persons, aged 65 and over were approached. The response rate was 85% (n = 194). Depression was assessed by the Center for Epidemiologic Studies Depression (CES-D) Scale. MAIN RESULTS: Controlling for caregivers' income, education, health status, and caregiving stress, religiosity was associated with more depressive symptoms among children caregivers while for spouses the association was negative. Emotional support was negatively associated with depression, but instrumental support was not significant. CONCLUSIONS: Depressive symptomatology is frequent among Spanish caregivers of disabled elderly. This study concludes that religiosity and family emotional support play an important part in the mental health of Spanish caregivers. The role of religiosity may be different according to kinship tie and needs further investigation.

Activities of Daily Living↗
PubMed1999

Patient care following carotid endarterectomy.

Individuals with carotid artery disease often enter the health care system for surgery. Since carotid endarterectomy is a surgical procedure with associated risks, it is essential for health care providers to understand operative interventions and cardiac and neurologic responses to provide competent postoperative care.

Carotid Stenosis↗
PubMed1996

Jugular thrombophlebitis complicating bacterial pharyngitis (Lemierre's syndrome).

Lemierre s syndrome is a rare syndrome caused by Fusobacterium necrophorum, a gram-negative anaerobic organism that normally inhabits the oropharynx. The syndrome follows primary oropharyngeal infection and affects previously healthy adolescents in a characteristic manner with fatal results if left untreated. The authors present two cases seen at their institution and discuss the clinical and radiologic features of the syndrome, along with considerations for patient management.

Adolescent↗