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At least 1,189 records · Page 66Linked to original sources
PubMed1997

A modular six-directional force sensor for prosthetic assessment: a technical note.

A device designed to measure the forces and moments transmitted through prostheses of persons with lower limb amputation is presented. The sensing unit design is an advancement over previous prosthesis force measurement devices in that it is very thin (19 mm) and lightweight (527.5 g, including signal-conditioning instrumentation). The disk-shaped transducer fits between the socket and socket adapter of a standard modular prosthesis, measuring all six force and moment components at this location. Twelve strain gages were used, configured into six two-arm active Wheatstone bridge circuits. A 6X6 matrix was constructed from calibration data to relate the 6-component bridge-output vector to a 6-component force and moment vector. In a bench-test setting, the sensor was evaluated under typical load combinations encountered during the walking of a person with transtibial amputation (TTA) and shown to have errors less than 7.2% of the full-scale output for each direction. Data collected on a subject with TTA walking at different speeds are presented.

Amputation, Surgical↗
PubMed1976

Modular total knee-replacement arthroplasty. A review of eighty-nine patients.

Fifty-eight osteoarthritic and thirty-one rheumatoid patients underwent modular total knee-replacement arthroplasty. The major indication for the operation was relief of pain. Contraindications to this resurfacing arthroplasty included varus-valgus instability of over 20 degrees, combined varus-valgus instability with flexion contracture of over 40 degrees, marked recurvatum, and predominant patellofemoral symptoms. In 59 per cent of the osteoarthritic and 58 per cent of the rheumatoid patients, complete relief of pain was evident when they were evaluated twenty-four months after surgery, while another 35 per cent of each group had only mild pain related to inclement weather. Their ability to walk long distances without support or limp was increased. Range of motion and ability to climb stairs were not significantly improved.

Aged↗
PubMed1997

[Development of treatment guidelines and procedure guidelines within the scope of developing case fees and a modular quality management system (MQM)].

Since 1991 Diagnostic Related Groups (DRGs) are systematically developed for standardized operation procedures. They are included in a Quality Management System of the DIN EN ISO 9001 ff. norm and are part of the process system. In additional the internal and external evaluation of quality completes a Modular Quality Management System (MQM). These procedures meet the requirements for a Total Quality Management (TQM).

Algorithms↗
PubMed1997

Modular data acquisition system updated using LabWindows/CVI Graphical User Interface.

The Biomechanics Laboratory of the Neuroscience Department of the Medical College of Wisconsin is currently engaged in research involving trauma biomechanics. For some experiments, 24 channels of analog data must be sampled at 10,000 Hertz. The Modular Data Acquisition System (MDAS) is able to acquire up to 60 channels of analog data at sampling intervals as low as 6 microseconds. This excellent hardware system has only menu-driven utility software that is no longer supported and required updating to a Graphical User Interface (GUI). Using National Instruments LabWindows/CVI software a GUI was developed. The GUI consists of 9 Graphical User Interface panels controlled by a 3000 line C program "MDAS3SAM". "MDAS3SAM" controls a driver program "MDAS_SAM" which communicates with the MDAS unit via a National Instruments GPIB interface. The 9 GUI panels allow the user to configure the MDAS system (selecting channels, sampling interval, triggering levels etc.), start sampling the data, writing the data to hard disk, graphing the data and printing the graphs. The new system allows the user to quickly reconfigure the MDAS unit and obtain accurate results.

Biomechanical Phenomena↗
PubMed1976

The Modular (Marmor) knee: case report with a minimum follow-up of 2 years.

A follow-up of 2 years or more on 105 patients with the Modular (Marmor) knee replacement revealed that 88 per cent of the patients had a successful result. The complications and failures are analyzed in depth. Late loosening of the components was not observed except with the 6 mm tibial plateau. Pain relief was dramatic as well as improved function, stability and motion.

Adult↗
PubMed1999

Multiple docking sites on substrate proteins form a modular system that mediates recognition by ERK MAP kinase.

MAP kinases phosphorylate specific groups of substrate proteins. Here we show that the amino acid sequence FXFP is an evolutionarily conserved docking site that mediates ERK MAP kinase binding to substrates in multiple protein families. FXFP and the D box, a different docking site, form a modular recognition system, as they can function independently or in combination. FXFP is specific for ERK, whereas the D box mediates binding to ERK and JNK MAP kinase, suggesting that the partially overlapping substrate specificities of ERK and JNK result from recognition of shared and unique docking sites. These findings enabled us to predict new ERK substrates and design peptide inhibitors of ERK that functioned in vitro and in vivo.

3T3 Cells↗
PubMed1999

High-efficiency gene targeting in Schizosaccharomyces pombe using a modular, PCR-based approach with long tracts of flanking homology.

Bähler et al.(1998) recently described a PCR-based system for the deletion, tagging and overexpression of endogenous genes in the fission yeast Schizosaccharomyces pombe. A small set of PCR primers can be used to generate gene-targeting substrates from each of several modules that differ in the selectable marker (ura4(+) or kanMX6), the presence or absence of specific epitope tags (HA, Myc, GST or GFP), the position in which the epitopes will be inserted (C- or N-terminal), and the presence or absence of a regulatable promoter (the nmt1 promoter). This is a straightforward and powerful system: nine different genes were C-terminal tagged at an average efficiency of 73%, using primers producing only 60-81 bp of homology. In contrast, when studying three transcriptionally-silent genes (rec8(+), rec10(+) and rec11(+)) we obtained an average homologous integration efficiency of 4% for 12 targeting constructs when using primers that contained 80 bp of homology. By using a PCR-based increase in the amount of flanking homology to >/=250 bp, we obtained homologous integration efficiencies of up to 100%. Thus, loci of S. pombe that are refractory to gene targeting when using short tracts of homology can be readily modified by increasing the extent of homology flanking the targeting modules. This straightforward and cost-effective approach might therefore be the one of choice for the modification of S. pombe loci in general and of targeting-refractory loci in particular.

Chromosome Mapping↗
PubMed1996

A high-performance modular data system for Fourier transform ion cyclotron resonance mass spectrometry.

The three major components of a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer include the vacuum system (including ion source), the magnet and a data system capable of performing the necessary instrument control for desired experiments. Most previous FTICR systems have used commercial data systems based on custom-built electronics controlled by proprietary mini-computers developed in the early 1980's. Here we present a high-performance data system based on a personal computer running user-friendly Windows software and readily available commercial components contained in a VXI chassis and a minimal complement of simple custom electronics. The system uses a VXI pattern generator to control all aspects of the experiment. The flexibility of the pattern generator allows for performance of all current FTICR experimental sequences.

Cyclotrons↗
PubMed1999

Modular organization of human leg withdrawal reflexes elicited by electrical stimulation of the foot sole.

Human withdrawal reflex receptive fields were determined for leg muscles by randomized, electrical stimulation at 16 different positions on the foot sole. Tibialis anterior, gastrocnemius medialis, peroneus longus, soleus, rectus femoris, and biceps femoris reflexes, and ankle joint angle changes were recorded from 14 subjects in sitting position. Tibialis anterior reflexes were evoked at the medial, distal foot and correlated well with ankle dorsal flexion. Gastrocnemius medialis reflexes were evoked on the heel and correlated with plantar flexion. Stimulation on the distal, medial sole resulted in inversion (correlated best with tibialis anterior activity), whereas stimulation of the distal, lateral sole evoked eversion. Biceps femoris reflexes were evoked on the entire sole followed by a small reflex in rectus femoris. A detailed withdrawal reflex organization, in which each lower leg muscle has its own receptive field, may explain the ankle joint responses. The thigh activity consisted primarily of flexor activation.

Adult↗
PubMed1996

Neural network modeling of the hippocampal formation spatial signals and their possible role in navigation: a modular approach.

Cells throughout the hippocampal formation show striking spatial firing correlates as a rat navigates through space. These cells are thought to play a critical role in orchestrating the navigational abilities of the animals, since damage to the hippocampal formation causes spatial learning deficits. Here, we present a theoretical framework aimed at explaining how the different spatial signals are generated, as well as how they may help guide navigational behavior. Earlier work from our laboratory has presented a simple model for how the location-related signals exhibited by hippocampal place cells could be generated, based on convergent sensory information. Here, the results of this work are combined with two more recent models, to provide a more comprehensive theoretical framework. Specifically, we present 1) A neural network model of head direction cells, based on the idea that the directional signals are generated using a path integration mechanism. Cells which combine directional and angular head velocity information project onto the head direction cells, to "update" the current directional signal. This model reproduces the basic phenomenon of direction-specific firing, as well as the anticipatory nature of this firing, reported for some head direction cells. 2) A network simulation of how the hippocampal spatial signals could be used to orchestrate instrumental learning. Here, place and directional signals converge onto motor cells, each of which are thus driven to fire to specific combinations of location and directional heading. Each active motor cell generates a small leftward or rightward "step" of the simulated animal. When the simulated goal is encountered, recently active synapses are strengthened, so that goal-directed trajectories are "stamped in". We have found these models useful in helping to clarify our thinking about the proposed theoretical principles, as well as in generating testable predictions.

Animals↗
PubMed2000

Novel Ruthenium Building Blocks for the Efficient Modular Construction of Heterobimetallic Molecular Squares of Porphyrins This work was supported by the Italian MURST. We thank Prof. L. G. Marzilli (Emory University, Atlanta, USA) for helpful discussions, and Johnson Matthey for a loan of RuCl(3) small middle dotx H(2)O. The CNR staff at ELETTRA is acknoweldged for help in the use of the facility supported by CNR and Elettra Scientific Division.

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Journal Article↗
PubMed2000

Modular regulation of the MLC1F/3F gene and striated muscle diversity.

Isoform diversity in striated muscle is largely controlled at the level of transcription. In this review we will concentrate on studies concerning transcriptional regulation of the alkali myosin light chain 1F/3F gene. Uncoupled activity of the MLC1F and 3F promoters, together with complex patterns of transcription in developing skeletal and cardiac muscle, combine to make analysis of this gene particularly intriguing. In vitro and transgenic studies of MLC1F/3F regulatory elements have revealed an array of cis-acting modules that each drive a subset of the expression pattern of the two promoters. These cis-acting regulatory modules, including the MLC1F and 3F promoter regions and two skeletal muscle enhancers, control tissue-specificity, cell or fibre-type specificity, and the spatiotemporal regulation of gene expression, including positional information. How each of these regulatory modules acts and how their individual activites are integrated to coordinate transcription at this locus are discussed.

Animals↗
PubMed2002

Ways of assembling complex natural products on modular nonribosomal peptide synthetases.

Nonribosomal peptide synthetases (NRPSs) catalyze the assembly of a large number of complex peptide natural products, many of which display therapeutically useful activity. Each cycle of chain extension is carried out by a dedicated module of the multifunctional enzymes. A module harbors all the catalytic units, which are referred to as domains, necessary for recognition, activation, covalent binding, and optionally modification of a single building block monomer, as well as for peptide-bond formation with the growing chain. A terminal domain releases the full-length peptide chain from the enzyme complex. Recent characterization of many NRPS systems revealed several examples where the sequence of the product does not directly correspond to the linear arrangement of modules and domains within the enzyme(s). It is now obvious that these systems cannot be regarded as rare exceptions of the common NRPS architecture but rather represent more complicated variations of the NRPS repertoire to increase their biosynthetic potential. In most of these cases unusual peptide structures of the products are observed, such as structures with side-chain acylation, cyclization involving the peptide backbone and/or side chains, and transfer of the peptide chain onto soluble small-molecule substrates. These findings indicate a previously unexpected higher versatility of the modules and domains in terms of both catalytic potential and interaction within the multifunctional protein templates. We propose to classify the known NRPS systems into three groups, linear NRPSs (type A), iterative NRPSs (type B), and nonlinear NRPSs (type C), according to their biosynthetic logic. Understanding the various biosynthetic strategies of NRPSs will be crucial to fully explore their potential for engineered combinatorial biosynthesis.

Acylation↗
PubMed2000

Modular chemistry with aluminum phosphanides: cluster formation of (AlP)n (n=3,6,7), Al4P3, and Al4Li4P6 frameworks.

The Al3P3 heterocycle 1 is formed in 94% yield by the reaction of the primary silylphosphane 6a with Me3Al in toluene at 70 degrees C. While 1 crystallizes in an isomerically pure form, in which the six-membered Al3P3 ring prefers the chair conformation and the P-H hydrogen atoms adopt exo positions, it isomerizes in solution to give different diastereomers as shown by 1H and 31P NMR spectroscopy. Intermolecular cyclocondensation of 1 at 110 degrees C in toluene leads, under liberation of methane, to the distorted hexameric-prismatic (AlP)6 cluster 2 in 98% yield. The capability of 1 to function as a building block was further used for the synthesis of the solvent-separated ion pair [Li(thf)2]+ [(Me2Al)4(PR)3]- (3) which was prepared by a one-pot reaction of 1 with nBuLi and Me2AlCl in 15% yield. The structure of 3 was established by an X-ray diffraction analysis. Double deprotonation at phosphorus in 1 with RPLi2 (R = iPr3Si) (molar ratio 1:2), and subsequent transformation of the reaction mixture with Me3Al afforded the novel donor-solvent-free cluster 4 in 62% yield. The latter consists of a rhombododecahedral Al4Li4P6 framework, in which the Li centers are three-coordinate. The reaction of the silylphosphane 6b with the trimethylamine adduct of alane furnishes not only the hexamer (RPAIH)6 (R = (iPrMe2C)-Me2Si) but also the corresponding heptamer 5, which has a nonregular polyhedral (AIP)7 framework and represents the first cluster of this type.

Journal Article↗
PubMed2002

Modular bis(oxazoline) ligands for palladium catalyzed allylic alkylation: unprecedented conformational behaviour of a bis(oxazoline) palladium eta3-1,3-diphenylallyl complex.

New families of enantiopure bis(oxazolines) with 4,5-trans (5 a-g) or 4,5-cis (6 c) stereochemistry at the individual rings have been prepared in high yield. Their eta(3)-allyl palladium complexes (8 a-g, 9 c and 10) have been used as catalytic precursors in allylic alkylation reactions with excellent enantioselectivities (up to 96 %) for the trans oxazoline derivatives, while Pd/6 c system was inactive. NMR studies on palladium eta(3)-1,3-diphenylallyl intermediates (11 a, c and e) showed the presence of syn/syn- and syn/anti-allyl isomers in solution; this resembles the first example of eta(3)-eta(1)-eta(3) isomerism in Pd allylic complexes containing bis(oxazolines) derived from malonic acid.

Journal Article↗