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Biomedical subjects

S Naumann

Publications and source records attributed to S Naumann.

At least 19 recordsLinked to original sources
PubMed2003

Systematic characterisation of silicon-embedded accelerometers for mechanomyography.

Silicon soft suction sockets (roll-on sleeves) currently used in passive prostheses for below-elbow amputees could also be used in externally powered prostheses, enhancing their functionality and comfort. However, as it is extremely difficult to hold currently used electromyography (EMG) sensors in place reliably within a silicon socket, an alternative measurement of muscular activity as the control input is necessary. Mechanomyography (MMG) is the epidermal measurement of the low-frequency vibrations produced by a contracting muscle. MMG sensors do not have to be in direct contact with the skin. Moreover, the embedding of sensors in the roll-on sleeve may also solve attachment issues, making sensor placement flexible. Therefore the objective was to determine the feasibility of recording MMG signals using silicon-embedded, micro-machined accelerometers. Fifteen embedded accelerometers were excited with predefined vibration patterns. The signal-to-noise ratio (SNR) and frequency response of each sample were measured and compared with those of non-embedded accelerometers. The SNR of embedded samples (approximately equal to 19 dB) was significantly higher than that of non-embedded samples (approximately equal to 12 dB), owing to the considerable mechanical damping effect of the silicon in the 300-900 Hz bandwidth (p=0.0028). This has implications for the application of silicon-embedded accelerometers for externally powered prosthesis control.

Amputation, Surgical↗
PubMed2001

Complete karyotype characterization of the K562 cell line by combined application of G-banding, multiplex-fluorescence in situ hybridization, fluorescence in situ hybridization, and comparative genomic hybridization.

This study combines conventional cytogenetics, fluorescence in situ hybridization (FISH), multiplex-FISH and comparative genomic hybridization (CGH). In applying this multimodal approach on the human leukemia cell line K562, the chromosome composition was refined in detail and compared with data from the literature. A hypotriploid karyotype with a modal chromosome number of 67, and 21 unique marker chromosomes were identified. The classification of six markers was identical to published data and the composition of five further markers from the literature could be fully clarified for the first time. The composition of another five markers, which have been interpreted in divergent ways in different studies, were elucidated without doubt. Finally, five new markers of our study seem to have no equivalents in former studies, very likely due to limitations of conventional cytogenetics. The combinatory application of complementary techniques as shown in this study will be very useful to provide the basis of a refined genotype analysis on the chromosomal level.

Chromosome Mapping↗
PubMed2001

Managing waiting patients' perceptions: the role of process control.

In a study of 195 patients visiting the urgent care department of a hospital in the UK, we examined the effects of three elements of process control on patients' fairness and satisfaction perceptions. Patients who believed they had a voice in the triage process had higher fairness perceptions and waited a shorter period of time than those who believed they did not have a voice in the triage process. In addition, patients who were told the expected waiting time and were kept busy while waiting had higher satisfaction perceptions. We identify implications for hospital employees in managing the patient waiting process.

Adult↗
PubMed2001

Genomic imbalances in 61 renal cancers from the proximal tubulus detected by comparative genomic hybridization.

Comparative genomic hybridization (CGH) has been applied to characterize 61 primary renal cell carcinomas derived histogenetically from the proximal tubulus. The tumor samples comprised 46 clear-cell renal cell carcinomas (ccRCCs) and 15 papillary renal cell carcinomas (pRCCs). Changes in the copy number of entire chromosomes or subregions were detected in 56 tumors (92%). In ccRCCs, losses of chromosome 3 or 3p (63%); 14q (30%); 9 (26%); 1 and 6 or 6q (17% each); 4 and 8 or 8p (15% each); 22 (11%); 2 or 2q and 19 (9% each); 7q, 10, 16, 17p, 18, and Y (7% each); and 5, 11, 13, 15, and 21 (4% each) were detected. Most frequent genomic gains in ccRCC were found on chromosome 5 (63%); 7 (35%); 1 or 1q (33%); 2q (24%); 8 or 8q, 12, and 20 (20% each); 3q (17%); 16 (15%); 19 (13%); 6 and 17 or 17q (11% each); and 4, 10, 11, 21, and Y (9% each). In pRCCs, gains in the copy number of chromosomes 7 and 17 (7/15, each) and 16 and 20 (6/15, each) were frequent. One pRCC showed amplification of subchromosome regions 2q22-->q33, 16q, 17q and the entire X chromosome. In pRCC, losses were less frequently seen than gains. Losses of chromosomes 1, 14, 15, and Y (3/15 each) and 2, 4, 6, and 13 (2/15 each) were observed. In ccRCCs, statistical evaluation revealed significant correlations of chromosomal imbalances with tumor stage and grade, i.e., a gain in copy number of chromosome 5 correlated positively with low tumor grade, whereas a gain of chromosomes 10 and 17 correlated positively with high tumor grade. Furthermore, loss of chromosome 4 correlated positively with high tumor stage.

Adenocarcinoma, Clear Cell↗
PubMed2000

Autologous transplantation of in vivo purged PBSC in CML: comparison of FISH, cytogenetics, and PCR detection of Philadelphia chromosome in leukapheresis products.

To determine the effectiveness of different methods for the detection of tumor cell contamination of collected peripheral stem cells, we performed a study on 39 chronic myelogenous leukemia (CML) patients who were consecutively treated at our department. Analyses of tumor cell contamination by fluorescence in situ hybridization (FISH), conventional cytogenetics, and polymerase chain reaction (PCR) showed marked differences in the percentage of evaluable results: Quantitative analysis of tumor cell contamination was feasible in 60 of 105 (57%) samples evaluated with the use of conventional cytogenetic analysis and in 105 of 107 (98%) samples analyzed by FISH. PCR was evaluable in all 85 samples tested (100%). Both methods were shown to be adequate overall in determining the number of BCR-ABL positive cells, although cytogenetics tended to produce slightly higher percentages. Based on these results, we conclude that FISH performed on leukapheresis products is a rapid and reliable method for assessing the quality of these products and should be used for routine evaluation of tumor cell contamination of CML stem cell products.

Adult↗
PubMed2000

A structure-function study of nucleic acid-fluorenone complexes.

Several 2.7-bis-[(dialkylamino)-acetylamino]-fluoren-9-one derivatives (fluoramides) were synthesized as analogues of the DNA binding compound tilorone (2,7-bis[(diethylamino)-ethoxy]-fluoren-9-one). Previous studies showed the drugs to induce cytokines and inhibit reverse transcription. Here, their binding to DNA was evaluated using UV and circular dichroism studies. Like tilorone, the fluoramides derivatives also intercalate resulting in increased Tm values and new CD signatures. A preference to alternating A-T and G-C sequences was detected; only minor interaction to homologous sequences was observed. Moreover, no upper limit in the drug/DNA ratio was found, testing limit being the precipitation of the drug. However, surface plasmon resonance (SPR) studies of tilorone and 2,7-bis-[(dipropylamino)-acetyl-amino]-fluoren-9-one, indicate an astonishing drug/base pair ratio (r > 1), which point to a multitude of interactions under SPR conditions. Molecular modeling calculations, where the geometries of the complexes optimized under the assumption of intercalative and multitude of suprahelical arrangements, rationalize the observations. Based on the thermodynamic and biological studies, a structure-function model is proposed.

Animals↗
PubMed2000

Biomesogenic matrix systems.

The bifunctionally reactive nucleoside and distant nucleoside analogs adenosine (Ado), S-[(adenine-9-yl)methoxyethyl]-L-cysteine (Na-salt) (cysA) and 9-vinyladenine (vA) in aqueous solutions assemble on complementary polyuridylic acid templates to form complex lyomesophases. The systems are investigated by polarizing microscopy, differential scanning calorimetry (DSC) and 1H- and 31P-nmr spectroscopies, assisted by molecular modeling studies. The results indicate the importance of biomesogenic (pre)ordering in nucleic acid native and artificial matrix reactions.

Adenine↗
PubMed1998

Quantification of antagonist muscle coactivation in children with spastic diplegia.

The purpose of this study was to investigate the use of the Pearson Product-Moment correlation coefficient to quantify muscle coactivation using electromyography. The subjects were two children with spastic diplegia. Surface electrodes were used to record muscle activity from the soleus and tibialis anterior muscles during voluntary attempts at dorsiflexion and plantarflexion of the ankle against resistance. The linear envelope signals were smoothed with a Hamming filter at a cutoff frequency of 4 Hz and intervals of the resultant pairs of curves subjected to the PPM test. Both subjects demonstrated significant coactivation on their right side and independent activity on the left, indicated by high positive and negative coefficients, respectively. This method shows promise for description of side differences in diplegics and for assessing the effects of physical therapy and other interventions.

Cerebral Palsy↗
PubMed1998

Evaluation of selective dorsal rhizotomy for the reduction of spasticity in cerebral palsy: a randomized controlled tria.

Selective dorsal rhizotomy (SDR) is widely used to treat spasticity in children with diplegic cerebral palsy (CP) but has never been shown conclusively to improve functional outcome. The study was designed to measure changes in gross motor function in children 1 year following rhizotomy compared with a control group receiving equivalent physiotherapy (PT) and occupational therapy (OT) with the exception that the rhizotomy group initially underwent a 6-week postoperative in-patient therapy program. Twenty-four children (mean age 58 months) with mild to moderate CP with spastic diplegia were randomly assigned to a therapy-only control group (CG) (N=12) or rhizotomy and therapy group (RG) (N=12). The Gross Motor Function Measure (GMFM) was administered at the baseline, 6-, and 12-month assessments. Extremity tone, range of motion (ROM), biomechanics of the ankle-stretch reflex, isometric contraction, and temporal gait components were also evaluated. GMFM scores in the RG improved by 12.1 percentage points versus 4.4 percentage points in the CG (P<0.02). RG knee and ankle tone was significantly reduced (P<0.005), associated with increased passive ankle ROM (P<0.001), and decreased soleus EMG reflex activity on forced dorsiflexion (P<0.008). Foot-floor contact pattern improved in the RG compared with the CG (P<0.05). In conclusion, SDR combined with PT and OT leads to significantly greater functional motor improvement at 1 year following surgery compared with PT and OT alone. This was achieved in part through reduced knee and ankle tone, increased ankle dorsiflexion ROM, and more normal foot-floor contact during walking.

Analysis of Variance↗
PubMed1996

Outcomes measurement of assistive technologies: an institutional case study.

The assistive technology (AT) community has been challenged to effectively measure the outcomes of AT services. There has been much discussion recently in the literature about how to conceptualize and respond to this challenge. In this paper, we suggest that these objectives are best accomplished when AT services are understood within the contexts of the total rehabilitation of AT users and the institutional culture in which services are delivered. We provide examples of outcome priorities we have identified and the tools and approaches we have used. These include projects in the areas of clinical, functional, and psychosocial outcomes assessment of ATs.

Activities of Daily Living↗
PubMed1994

Feedback of triceps surae EMG in gait of children with cerebral palsy: a controlled study.

Children with spastic hemiplegia secondary to cerebral palsy show disrupted patterns of work and power in gait. A computer-assisted feedback system was used to deliver EMG feedback from the triceps surae muscle group to walking subjects in conjunction with amplitude and timing targets for muscle relaxation and activation. Biofeedback of triceps surae muscle activity during gait was compared with physical therapy (PT) in a two-period crossover design, with intervening biomechanical gait analyses to assess the effects of each type of treatment. Kinematic and kinetic gait variables were affected differently by each type of treatment. Stride length and velocity were positively affected by the biofeedback protocol. Positive work done by the affected ankle increased through PT, but gait symmetry was negatively affected, such that the stance phase was prolonged, and peak ankle power at push-off was not improved. In contrast, the biofeedback treatment improved gait symmetry, and was associated with greater ankle power for push-off, as well as increases in total positive work at the hip and ankle. It is concluded that the feedback protocol might be an effective adjunct to physical therapy in hemiplegic children.

Adolescent↗
PubMed1993

Analytical procedures and quality assurance criteria for the determination of major and minor deoxynucleosides in fish tissue DNA by liquid chromatography-ultraviolet spectroscopy and liquid chromatography-thermospray mass spectrometry.

Analytical procedures and quality assurance criteria have been established for enzymatic hydrolysis of fish tissue DNA to free nucleosides and their subsequent characterization by liquid chromatography-photodiode-array ultraviolet spectroscopy and liquid chromatography-thermospray mass spectrometry. Optimization of enzymatic efficiency to assure minimal loss of modified nucleosides is described. Variability in analyte capacity factors and multiwavelength response have been compared for analyte standards and hydrolysates, and results have been used to derive qualitative and quantitative quality assurance criteria. A comparison of DNA mole percent calculated using single-wavelength quantification and multiwavelength averaging quantification indicates that less variability in data may be expected using the multiwavelength technique. Finally, the composition of DNA from liver of three species of fish widely used in mutagen/carcinogen laboratory and field studies, rainbow trout (Onchorynchus mykiss), medaka (Oryzias latipes), and brown bullhead (Ictalurus nebulosus), has been determined. Identification of deoxyuridine in the DNA hydrolysates of each fish indicates that this analyte should be measured to accurately report DNA deoxynucleoside mole percent, especially when reporting data for the methylation of deoxycytidine.

Animals↗
PubMed1993

In vivo microdialysis sampling of phenol and phenyl glucuronide in the blood of unanesthetized rainbow trout: implications for toxicokinetic studies.

Microdialysis (MD) is a sampling method that allows continuous in vivo collection of free, unbound chemicals in blood and interstitial fluids. In the present study we describe a surgical method for placement of a MD probe in the dorsal aorta of 600- to 900-g rainbow trout (Onchorhynchus mykiss). A specially designed probe guide was inserted into the dorsal aorta via the mouth. A PE-50 polyethylene cannula was then inserted into the probe guide and used to further position and maintain the probe guide in the dorsal aorta. Once proper placement of the probe guide was ascertained, the cannula was removed and a CMA-10 MD probe (4-mm tip) was inserted. The animal was then placed into a respirometer-metabolism chamber and allowed to recover from anesthesia. The placement and functionality of the probe were evaluated by examining the in vivo toxicokinetics of phenol (PH) and phenyl glucuronide (PG) in the blood of an unanesthetized rainbow trout exposed to water-borne PH (7.0 mg/liter). Prior to and following the introduction of PH into the metabolism chamber, MD samples (150 microliters) were collected at 30-min intervals and analyzed for free plasma PH and PG by HPLC. Total PH in exposure water and blood was also monitored every 30 min. Free PH and total PH in plasma accumulated rapidly and reached apparent steady-state levels of 54 and 142 pmol/microliters, respectively, in about 60 min. A blood:water partition coefficient of 2.0-2.6 was determined from these data, while bound and free plasma PH were 60 and 40%, respectively. PG was not detected until approximately 90 min of PH exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Soluble intercellular adhesion molecule-1 levels in patients with psoriasis.

A newly developed ELISA was used to detect and quantify the presence of a soluble form of intercellular adhesion molecule-1 (sICAM-1) in the circulation of healthy individuals compared with patients with psoriasis vulgaris. Seventeen psoriatic patients were studied. The extent of skin lesions was rated by the psoriasis area and severity index (PASI). Seventeen age- and sex-matched healthy individuals served as controls. Serum levels were measured by an ELISA technique utilizing an anti-ICAM-1 murine monoclonal antibody bound to the solid phase, and a second, peroxidase-conjugated monoclonal antibody reacting with sICAM-1. Serum levels in controls were 358.8 +/- 87.9 ng/ml sICAM-1, and 480.5 +/- 133.6 ng/ml in psoriatics (mean +/- SD; P = 0.02). In psoriasis, sICAM-1 levels were found to be directly proportional to the PASI score (y = 363.002 + 8.525x, R = 0.55, P = 0.021). These data suggest that the concentration of sICAM-1 in serum increases during psoriatic inflammation. The origin and function of sICAM-1 in psoriasis remain to be defined.

Adolescent↗
PubMed1992

Analysis of mechanical and metabolic factors in the gait of congenital below knee amputees. A comparison of the SACH and Seattle feet.

Prosthetic feet have been developed with the intention that they deform during the first half of the stance phase to store energy that can be released at the end of stance and contribute to push-off. The purpose of this study was to examine the three-dimensional kinematics and kinetics of gait and metabolic energy cost in children and adolescents with below-knee amputations using the SACH and Seattle prosthetic feet. The metabolic test consisted of an 8-min walk around an oval track while expired gases were collected and analyzed. The biomechanical test consisted of 10 walking trials: 5 for each of the prosthetic and sound limbs. Stance and swing phase moments and powers were calculated for both the prosthetic and sound limbs. A four-camera VICON system recorded movements of the limb segments to calculate joint kinematics, and these were combined with ground reaction force data in a three-dimensional model to determine moments and powers about the hip, knee and ankle joints. The Seattle foot produced a small increase in stride length, which led to a small increase in walking velocity. Biomechanical data revealed that the Seattle foot was less resistant to passive dorsiflexion in midstance, and although there was no effect on the work done across the prosthetic ankle, a knee flexor moment dominated the stance phase when the SACH foot was tested, whereas the Seattle foot allowed a normal extensor moment. The profile of work was unaffected by the type of foot. On the sound side, the hip produced most of the positive work while the ankle output was below normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Stretch reflex inhibition using electrical stimulation in normal subjects and subjects with spasticity.

The effect of electrically stimulating the tibialis anterior muscle on the stretch reflex of the soleus muscle in normal subjects and subjects with spasticity is investigated. Stimulation of the tibialis anterior just prior to the onset of a mechanical disturbance, which causes a stretch in the soleus, inhibits the stretch reflex of the soleus in normal subjects and may inhibit clonus in subjects with spasticity.

Biomechanical Phenomena↗
PubMed1990

Development of an integrated wheelchair tray system for augmentative communication.

This paper describes the development of a wheelchair tray system for persons with physical disabilities who require an augmentative communication system. The tray system offers advantages over existing systems by providing a convenient anterior/posterior tilt feature, a means for stowing the tray when not in use, and a method of accommodating communication systems and powered wheelchair controls. Caregivers of seven subjects fitted with the prototype system assessed its performance through the completion of questionnaires provided at the end of 6-week field trials. The technical performance of the systems was also monitored. The prototype system was favorably received by six participants. Several recommendations are made to further increase consumer acceptance of the final tray design.

Adolescent↗