Multi-modal access method (eye-tracking + switch-scanning) for individuals with severe motor impairment: A preliminary investigation.

Individuals with severe motor impairments often require alternative means to access computers and communication technology. A range of alternative access devices exist; however, most rely on use of a single access modality. While this approach works for some individuals, it can be limiting for others. This study explored the use of a multi-modal prototype (eye-tracking + switch-scanning) on typing performance with a range of individuals with motor impairments. The multi-modal prototype was compared to eye-tracking alone for this study. Results indicated that the multi-modal prototype had significantly slower typing rate but significantly lower total errors compared to eye-tracking alone. Analysis of individual data revealed four subgroups of clinical relevance including individuals that 1) benefit from multi-modal, 2) benefit from eye-tracking, 3) demonstrate learning and 4) demonstrate fluctuating performance.

Multimodal Elimination for Intoxication with a Lethal Dose of Organic Mercury.

We here report on a case of massive organic mercury intoxication in a 40-year-old man that resulted in progressive multiorgan failure. We treated the patient intravenously and enterally with the chelating agent (RS)-2,3-bis(sulfanyl) propane-1-sulfonic acid (DMPS) in addition to hemodialysis. The patient was treated for 6 weeks and could successfully be weaned from mechanical ventilation and hemodialysis. He awoke and was sent to rehabilitation, but unfortunately died 7 months later from refractory status epilepticus. Autopsy revealed severe brain atrophy consistent with organ damage from massive mercury intoxication. The present case illustrates that bimodal DMPS application is sufficient for detoxification from lethal mercury levels, with an associated chance for weaning of organ support and survival to discharge. The case further reminds us of intoxication as a cause of multiorgan dysfunction. We propose to immediately initiate combined parenteral and enteral detoxification in cases of methyl mercury intoxication, especially in cases of high doses.

[Osteointegration of an alumina matrix composite ceramic with a porous surface: mechanical and histological results of an animal experiment]. / Osteointegration einer Alumina-Matrix-Composite-Keramik mit poröser Oberfläche: Eine mechanische und histologische Untersuchung im Tierversuch.

INTRODUCTION: The aim of this study was to analyse mechanically and histologically the osteointegration of porous-surfaced ceramic implants made of an alumina matrix composite (AMC) by assessing maximum shear strength and histomorphometric bone ongrowth. METHODS: The surfaces of the cylindrically shaped AMC test implants were characterised by a porosity of 40% and a pore size of 150 to 300 microm. A total of 24 test cylinders was implanted bilaterally into the femurs of 6 female adult Goettinger minipigs. 12 weeks after surgery the animals were sacrificed. 12 test implants were used for a push-out test and 12 test implants were evaluated histologically. RESULTS: The mean maximum shear strength of the bone-implant interface was 7.6 +/- 2.0 MPa. Direct bone attachment was found in 7.4 +/- 3.4% of the histologically analysed surfaces. CONCLUSION: In summary, porous-surfaced AMC test implants demonstrated good mechanical stability in spite of a low percentage of bone ongrowth. This discrepancy could potentially be explained by bone ingrowth into the pores and subsequent interlocking mechanisms.

High-throughput development and characterization of a genomewide collection of gene-based single nucleotide polymorphism markers by chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

We describe here a system for the rapid identification, assay development, and characterization of gene-based single nucleotide polymorphisms (SNPs). This system couples informatics tools that mine candidate SNPs from public expressed sequence tag resources and automatically designs assay reagents with detection by a chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry platform. As a proof of concept of this system, a genomewide collection of reagents for 9,115 gene-based SNP genetic markers was rapidly developed and validated. These data provide preliminary insights into patterns of polymorphism in a genomewide collection of gene-based polymorphisms.

User performance with speech recognition: a literature review.

The application of speech recognition to the computer access needs of people with disabilities continues to grow, and a greater understanding of user performance with such systems is needed. This article reviews what is known about user performance with speech recognition systems, with a focus on its application to accommodation of physical disability. Although current systems offer the potential of text entry at 150 words per minute, the literature suggests that users actually achieve somewhere between 8 and 30 words per minute. Barriers that may contribute to this gap, such as the costs associated with correcting recognition errors, are reviewed, and directions for future research are proposed. A major need is for additional research involving users who have physical disabilities.

Calcium dynamics associated with action potentials in single nerve terminals of pyramidal cells in layer 2/3 of the young rat neocortex.

Calcium dynamics associated with a single action potential (AP) were studied in single boutons of the axonal arbor of layer 2/3 pyramidal cells in the neocortex of young (P14-16) rats. We used fluorescence imaging with two-photon excitation and Ca2+-selective fluorescence indicators to measure volume-averaged Ca2+ signals. These rapidly reached a peak (in about 1 ms) and then decayed more slowly (tens to hundreds of milliseconds). Single APs and trains of APs reliably evoked Ca2+ transients in en passant boutons located on axon collaterals in cortical layers 2/3, 4 and 5, indicating that APs propagate actively and reliably throughout the axonal arbor. Branch point failures are unlikely to contribute to differences in synaptic efficacy and reliability in the connections made by layer 2/3 pyramidal cells. AP-evoked Ca2+ transients in boutons were mediated by voltage-dependent Ca2+ channels (VDCCs), predominantly by the P/Q- and N-subtypes. Ca2+ transients were, on average, of significantly larger amplitude in boutons than in the flanking segments of the axon collateral. Large amplitude Ca2+ transients in boutons were spatially restricted to within <= 3 m of axonal length. Single AP-evoked Ca2+ transients varied up to 10-fold across different boutons even if they were located on the same axon collateral. In contrast, variation of Ca2+ transients evoked by successive APs in a given single bouton was small (coefficient of variation, c.v. <= 0.21). Amplitudes of AP-evoked Ca2+ signals did not correlate with the distance of boutons from the soma. In contrast, AP-evoked Ca2+ signals in spines of basal dendrites decreased slightly (correlation coefficient, r2 = -0.27) with distance from the soma. Measurements with the low-affinity Ca2+ indicator Magnesium Green suggest that the volume-averaged residual free [Ca2+]i in a bouton increases on average by 500 nM following a single AP. Higher concentrations of indicator caused, on average, a decrease in the amplitude and an increase in the decay time constant of Ca2+ transients. Assuming a single-compartment model the concentration dependence of decay time constants suggests a low endogenous Ca2+ binding ratio close to 140, indicating that of the total Ca2+ influx ( approximately 2 fC) less than 1% remained free. The indicator concentration dependence of decay time constants further suggests that the residual free Delta[Ca2+]i associated with an AP decays with a time constant of about 60 ms (35 C) reflecting a high Ca2+ extrusion rate of about 2600 s(-1). The results show that AP-evoked volume-averaged Ca2+ transients in single boutons are evoked reliably and, on average, have larger amplitudes than Ca2+ transients in other subcellular compartments of layer 2/3 pyramidal cells. A major functional signature is the large variation in the amplitude of Ca2+ transients between different boutons. This could indicate that local interactions between boutons and different target cells modify the spatiotemporal Ca2+ dynamics in boutons and cause target cell-specific differences in their transmitter release properties.

NMDA spikes in basal dendrites of cortical pyramidal neurons.

Basal dendrites are a major target for synaptic inputs innervating cortical pyramidal neurons. At present little is known about signal processing in these fine dendrites. Here we show that coactivation of clustered neighbouring basal inputs initiated local dendritic spikes, which resulted in a 5.9 +/- 1.5 mV (peak) and 64.4 +/- 19.8 ms (half-width) cable-filtered voltage change at the soma that amplified the somatic voltage response by 226 +/- 46%. These spikes were accompanied by large calcium transients restricted to the activated dendritic segment. In contrast to conventional sodium or calcium spikes, these spikes were mediated mostly by NMDA (N-methyl-D-aspartate) receptor channels, which contributed at least 80% of the total charge. The ionic mechanism of these NMDA spikes may allow 'dynamic spike-initiation zones', set by the spatial distribution of glutamate pre-bound to NMDA receptors, which in turn would depend on recent and ongoing activity in the cortical network. In addition, NMDA spikes may serve as a powerful mechanism for modification of the cortical network by inducing long-term strengthening of co-activated neighbouring inputs.

Chromosome territories, interchromatin domain compartment, and nuclear matrix: an integrated view of the functional nuclear architecture.

Advances in the specific fluorescent labeling of chromatin in fixed and living human cells in combination with three-dimensional (3D) and 4D (space plus time) fluorescence microscopy and image analysis have opened the way for detailed studies of the dynamic, higher-order architecture of chromatin in the human cell nucleus and its potential role in gene regulation. Several features of this architecture are now well established: 1. Chromosomes occupy distinct territories in the cell nucleus with preferred nuclear locations, although there is no evidence of a rigid suprachromosomal order. 2. Chromosome territories (CTs) in turn contain distinct chromosome arm domains and smaller chromatin foci or domains with diameters of some 300 to 800 nm and a DNA content in the order of 1 Mbp. 3. Gene-dense, early-replicating and gene-poor, middle-to-late-replicating chromatin domains exhibit different higher-order nuclear patterns that persist through all stages of interphase. In mitotic chromosomes early replicating chromatin domains give rise to Giemsa light bands, whereas middle-to-late-replicating domains form Giemsa dark bands and C-bands. In an attempt to integrate these experimental data into a unified view of the functional nuclear architecture, we present a model of a modular and dynamic chromosome territory (CT) organization. We propose that basically three nuclear compartments exist, an "open" higher-order chromatin compartment with chromatin domains containing active genes, a "closed" chromatin compartment comprising inactive genes, and an interchromatin domain (ICD) compartment (Cremer et al., 1993; Zirbel et al., 1993) that contains macromolecular complexes for transcription, splicing, DNA replication, and repair. Genes in "open," but not in "closed" higher-order chromatin compartments have access to transcription and splicing complexes located in the ICD compartment. Chromatin domains that build the "open" chromatin compartment are organized in a way that allows the direct contact of genes and nascent RNA to transcription and splicing complexes, respectively, preformed in the ICD compartment. In contrast, chromatin domains that belong to the "closed" compartment are topologically arranged and compacted in a way that precludes the accessibility of genes to transcription complexes. We argue that the content of the ICD compartment is highly enriched in DNA depleted biochemical matrix preparations. The ICD compartment may be considered as the structural and functional equivalent of the in vivo nuclear matrix. A matrix in this functional sense is compatible with but does not necessitate the concept of a 3D nuclear skeleton existing of long, extensively arborized filaments. In the absence of unequivocal evidence for such a structural matrix in the nucleus of living cells we keep an agnostic attitude about its existence and possible properties in maintaining the higher-order nuclear architecture. Quantitative modeling of the 3D and 4D human genome architecture in situ shows that such an assumption is not necessary to explain presently known aspects of the higher-order nuclear architecture. We expect that the interplay of quantitative modeling and experimental tests will result in a better understanding of the compartmentalized nuclear architecture and its functional consequences.

Adaptive one-switch row-column scanning.

Row-column scanning is a very slow method of communication. Options for increasing text entry rate include 1) dynamically changing the configuration of the row-column matrix or 2) using rate-enhancement techniques like word prediction, but evidence suggests that increased cognitive load imposed by these methods on the user can result in little or no improvement in text generation rate. An alternative we are investigating is adapting a system's scan delay during run-time. Our goal is to allow a scanning system to adjust its parameters "on the fly" (as opposed to the current practice of setting parameters during clinical assessments). This paper describes the evolution of a one-switch row-column scanning system that adapts its scan rate based on measurements of user performance. Two experiments have been performed to explore the effects of automatically adapting scan delay on users' text entry rate. Our results indicate that automatic adaptation has the potential to enhance text-entry rate without increasing task complexity.

Ca2+ fluorescence imaging with pico- and femtosecond two-photon excitation: signal and photodamage.

The signal and limitations of calcium florescence imaging using nonresonant multiphoton absorption of near-infrared femto- and picosecond laser pulses were examined. The fluorescence changes of various Ca(2+)-indicators induced by transient increases of the intradendritic calcium concentration were evaluated by evoking physiological activity in neocortical neurons in rat brain slices. Photodamage was noticeable as irreversible changes in the parameters describing the calcium fluorescence transients. At higher two-photon excitation rates, a great variety of irregular functional and structural alterations occurred. Thus, signal and observation time were limited by phototoxic effects. At lower excitation rates, photodamage accumulated linearly with exposure time. Femtosecond and picosecond laser pulses were directly compared with respect to this cumulative photodamage. The variation of the pulse length at a constant two-photon excitation rate indicated that a two-photon excitation mechanism is mainly responsible for the cumulative photodamage within the investigated window of 75 fs to 3.2 ps. As a direct consequence, at low excitation rates, the same image quality is achieved irrespective of whether two-photon Ca(2+)-imaging is carried out with femto- or picosecond laser pulses.

Calcium dynamics in single spines during coincident pre- and postsynaptic activity depend on relative timing of back-propagating action potentials and subthreshold excitatory postsynaptic potentials.

We compared the transient increase of Ca2+ in single spines on basal dendrites of rat neocortical layer 5 pyramidal neurons evoked by subthreshold excitatory postsynaptic potentials (EPSPs) and back-propagating action potentials (APs) by using calcium fluorescence imaging. AP-evoked Ca2+ transients were detected in both the spines and in the adjacent dendritic shaft, whereas Ca2+ transients evoked by single EPSPs were largely restricted to a single active spine head. Calcium transients elicited in the active spines by a single AP or EPSP, in spines up to 80 micro(m) for the soma, were of comparable amplitude. The Ca2+ transient in an active spine evoked by pairing an EPSP and a back-propagating AP separated by a time interval of 50 ms was larger if the AP followed the EPSP than if it preceded it. This difference reflected supra- and sublinear summation of Ca2+ transients, respectively. A comparable dependence of spinous Ca2+ transients on relative timing was observed also when short bursts of APs and EPSPs were paired. These results indicate that the amplitude of the spinous Ca2+ transients during coincident pre- and postsynaptic activity depended critically on the relative order of subthreshold EPSPs and back-propagating APs. Thus, in neocortical neurons the amplitude of spinous Ca2+ transients could encode small time differences between pre- and postsynaptic activity.

[Effects of quality assurance measures on surgical gynecology treatment]. / Effekte qualitätssichernder Massnahmen auf die operativgynäkologische Versorgung.

Basing on the example of the project "Quality assurance in gynaecological surgery", we show which effects due to participation in an externally supported quality assurance measure can be reached short-term. 44 gynaecological clinics documented 42,433 operative procedures within the project in 1994. In 1995, seven participants continued the documentation (9,430 operations). We measured the quality of care over time, using 20 quality indicators that were formulated in the project. Quality improvements were achieved in the two-year study period particularly for indicators which focused on less complex processes of care (i.e. thromboprophylaxis with heparin). However, more complex processes of care, such as the indication for an operation, have not yet changed. Nevertheless, according to the results of structured interviews, we expect long-term quality improvements: due to the participation in the project, 26 clinics reported increasing attention to the quality of care, 12 clinics changed their organisation of the quality assurance system and 11 clinics began internal quality improvement projects on the basis of the study benchmarks.

Learning and performance of able-bodied individuals using scanning systems with and without word prediction.

This study examines how the cognitive and perceptual loads introduced by a word prediction feature impact learning and performance. Two groups of able-bodied subjects transcribed text using two row-column scanning systems for 10 consecutive trials each. The two systems differed only in that one system had a word prediction feature. Subject groups differed in their order of system use. The results show that, under the conditions of this study, the word prediction system was not substantially more difficult to learn, but it did not yield a statistically significant improvement in text generation rate. This suggests that the cost of using this word prediction system balanced the benefit of the keystroke savings achieved by these subjects. The relationship between keystroke savings, cost in item selection rate, and improvement in text generation rate is explored in order to provide insight into this outcome.

[A district psychiatric clinic and therapeutic pedagogic facility--development of a management concept for mentally handicapped patients]. / Psychiatrische Landesklinik und Heilpädagogisches Heim--Entwicklung eines Versorgungskonzeptes für geistig Behinderte.

There is a general consensus of opinion that adult mentally handicapped persons--if we leave aside the treatment of severe and psychiatrically relevant concomitant diseases or abnormal behaviour--are misfits in a psychiatric hospital. The aim of an independent care of the mentally handicapped can be achieved in different ways based on medical paedagogy. The Home for Medical Paedagogy in Düren, Lower Rhine District, is a case in point. Despite many difficulties and conflicts this hospital attained an outstanding standard of medical care within just ten years. Its location is on the same site as that of the psychiatric hospital.

[Breast feeding studies 1981-1983 in 1,500 mothers in Dortmund and Haltern. III. Rates of breast feeding and duration of breast feeding in the first half year]. / Stillstudien 1981-1983 bei 1500 Müttern in Dortmund und Haltern. III. Stillraten und Stilldauer im 1. Lebenshalbjahr.

With two collectives of mothers from the large maternity wards in Dortmund (n = 998) and Haltern (n = 500) breast-feeding patterns were studied prospectively after dismissal. 95 and 93% of initially breast-feeding mothers kept simple protocols of duration and intensity of breast-feeding. 20 and 13% respectively of the breast-feeding mothers in Dortmund and Haltern stopped breast-feeding within 3 days following discharge, only 2 and 6% respectively of all mothers fully breast-fed for a period of a months as recommended. Already from the beginning of the 2nd month some mothers introduced (unnecessarily) juices as Beikost. Reasons given by the mothers for termination of breast-feeding were mostly connected with problems concerning the mother (50%) and nursing problems (35%). Statistical analysis (Cox proportional hazards model) revealed that the mothers' age (less than 25 years), low educational level, bad breast-feeding experience and use of a pump significantly reduce duration of breast-feeding. Promotion and support of breast-feeding is urgently needed especially during the first weeks after birth and with inexperienced, young and less educated mothers.

[1981-1983 breast feeding studies of 1,500 mothers in Dortmund and Haltern. II. Volume of breast milk in the maternity ward]. / Stillstudien 1981-1983 bei 1500 Müttern in Dortmund und Haltern. II. Muttermilchmengen auf der Entbindungsstation.

In two large maternity wards encouraging breast-feeding, breast-milk volumes (weighing of the baby before and after each feeding) and weight development of the infants were determined until dismissal. On days 2, 3 and 4, 20-30%, 60-70%, and 80-90% of the mothers, respectively, produced milk. The largest increase in milk volume ("Einschuss") usually took place between days 3 and 4. Milk volume increased from an average of 150-180 ml on day 4 to 270-300 ml on day 6. Development of milk production was independent of type of delivery; however, the usual delay of one day following caesarean section was not made up for until discharge. Fully breast-feeding mothers produced on the average the same amounts of milk as mothers at the turn of the century. Throughout their stay in the maternity ward, mothers with good breast-feeding experience produced more milk than those with bad or without any breast-feeding experience. Nursing all infants at fairly regular intervals during the day and at night is recommended in order to achieve that as many mothers as possible are fully breast-feeding on discharge. Comparing energy intake and weight development between groups of fully, partially and non breast-fed infants suggested a better utilization of breast-milk.

[1981-1983 breast feeding studies of 1,500 mothers in Dortmund and Haltern. I. Collectives studied and rates of breast feeding in the maternity ward]. / Stillstudien 1981-1983 bei 1,500 Müttern in Dortmund und Haltern. I. Studienkollektive und Stillraten auf der Entbindungsstation.

Rates of breast-feeding were studied in collectives of 998 mothers (Dortmund) and 500 mothers (Haltern) in two large maternity wards encouraging breast-feeding. In both hospitals the collectives were representative for the population in the surrounding region. Mothers were asked to take part in the study as they were admitted. Response rates were 99%. Age and parity of mothers in Dortmund were in agreement with population statistics, whereas in the Haltern collective there was a smaller proportion of younger mothers. The collective in Haltern had a slight edge with respect to social background. The different types of delivery had the same percentages in both wards. Birthweight was on the average 100 g higher in Haltern neonates. There were no differences in mean length. In both wards feeding on demand was practised during the rooming-in period during daytime, whereas at night infants were bottle-fed on demand in the infant's room. In Haltern supplementary formula feeding was offered more liberally. In Dortmund 92%, in Haltern 97% of the mothers tried to breast-feed; only 5% and 2% respectively were unsuccessful. Mothers who did not want to breast-feed (8% and 3% respectively) rarely mentioned relevant obstacles as a reason for their decision. On discharge 80-90% of the mothers were breast-feeding, with only about one half of them fully breast-feeding. Caesarean section was hardly detrimental to initiation of breast-feeding, but often to success.