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At least 271 records · Page 15Linked to original sources

PubMed1995

Temporomandibular joint mobility assessment: a comparison between four methods.

Temporomandibular joint (TMJ) mobility is assessed in different ways. Measurement of the interincisal distance in maximal mouth opening added to the vertical overlap of the dentition, i.e. linear mouth opening (LMO); measurement of angular displacement of the mandible relative to the cranium at maximal mouth opening, i.e. angle of mouth opening (AMO); assessment of the condylar position relative to the articular eminence performed on transpharyngeal radiographs in maximal mouth opening, i.e. condylar mobility (CM); measurement of angular displacement of the mandible at maximal mouth opening relative to the closed mouth position of the mandible, assessed on transpharyngeal radiographs in maximally opened and in closed mouth position, i.e., radiographic angle of mouth opening (RAMO). To compare these TMJ mobility assessment methods and to analyse the relationship between LMO, AMO and mandibular length (ML), 28 healthy volunteers (13 females, 15 males), mean age 29-6 years (range 21-41) with a symmetrical mouth opening pattern were assessed. LMO, AMO, ML, and RAMO were measured and CM was assessed on transpharyngeal radiographs. LMO and AMO were strongly and significantly related (r = 0.71). LMO was significantly influenced by AMO and ML. No significant differences between AMO and RAMO were found. CM was strongly and significantly related to AMO (r = 0.72) and weakly but significantly related to LMO (r = 0.42). Based on the results of this study recommendations are made regarding the appropriate application of TMJ mobility assessment methods.

Adult↗

PubMed2001

Development of an instrumented couch to measure forces during manual physiotherapy treatment.

This paper reports on an instrumented couch developed to measure the forces applied during posteroanterior (PA) mobilization to the lumbar spine. The couch was evaluated for reliability by applying known weights to the empty couch, while accuracy was investigated by applying weights both to the empty couch and to a human subject lying on the couch. The equipment appears highly reliable when measuring forces in three directions (ICC(2,1); 99% CI=0.99-1.00) and also demonstrates acceptable accuracy; a maximum error of less than 2% being obtained when measuring forces applied to human subjects. The results demonstrate a highly linear relationship (r2=0.99) between the force readings and the known weights. In conclusion, the instrumented couch demonstrates suitable accuracy and reliability for measuring the force applied to a subject during the application of PA mobilization to the lumbar spine.

Beds↗

PubMed1990

Effect of feedback on learning a vertebral joint mobilization skill.

This study was designed to investigate whether concurrent quantitative feedback of performance could improve the learning of a joint mobilization technique. A group of 110 physical therapy students had been randomly divided into two groups for teaching purposes. All students had previously learned mobilization of peripheral joints and were currently learning spinal mobilization. From one of the groups, 22 students volunteered to comprise a control group, which was taught a spinal mobilization technique in the traditional way. Additional concurrent quantitative feedback of the level of force applied to the patient was given to 31 volunteers from the other group. These students formed the experimental group. A force plate was used for force measurement, and the feedback was given via an oscilloscope. The average force applied by the students' instructors was taken as an "ideal" force. The oscilloscope showed both the applied force and the "ideal" force. Consistency was measured by the variance of the group's performance. Accuracy was assessed by calculating the difference between the applied force and the "ideal" force. Results indicated that this feedback was associated with a significant improvement in accuracy and consistency in the application of the mobilizing force. This improvement was still present at a follow-up test conducted one week later. This result supports a greater use of such feedback in the teaching and practice of joint mobilization techniques, although the need for further research is emphasized.

Adult↗

PubMed2002

In vivo skin penetration of salicylic compounds in hairless rats.

The in vivo skin penetration of four salicylic compounds was investigated using a hairless rat model, which allowed for non-occluded, finite dose application, and free mobility of the rats throughout the test period. The model compounds were applied in equimolal concentrations of 0.4 mmol/g dimethyl isosorbide. At certain times (0.5-24 h) the rats were killed, and the amount of test compound on the skin surface, in the stratum corneum, and in the deeper viable skin layers was determined. Significant different skin concentrations were found with the following ranking: [(14)C]diethylamine salicylate>[(14)C]salicylic acid>[(14)C]salicylamide>[(14)C]butyl salicylate. In addition, the in vivo percutaneous rate of absorption was in the following order: [(14)C]butyl salicylate>[(14)C]salicylic acid> or =[(14)C]salicylamide>[(14)C]diethylamine salicylate. [(14)C]Butyl salicylate was rapidly absorbed and completely depleted from the surface 3 h post application. In comparison with [(14)C]salicylic acid, the ionic [(14)C]diethylamine salicylate had larger surface depots and penetrated the skin at a lower rate. The relatively hydrophilic [(14)C]salicylamide also had larger surface depots but much lower skin levels. For comparison, the in vitro permeation of the formulations was studied through freshly excised hairless rat skin using Franz diffusions cells, and an agreement between the techniques was found.

Animals↗

PubMed2002

System for assisted mobility using eye movements based on electrooculography.

This paper describes an eye-control method based on electrooculography (EOG) to develop a system for assisted mobility. One of its most important features is its modularity, making it adaptable to the particular needs of each user according to the type and degree of handicap involved. An eye model based on electroculographic signal is proposed and its validity is studied. Several human-machine interfaces (HMI) based on EOG are commented, focusing our study on guiding and controlling a wheelchair for disabled people, where the control is actually effected by eye movements within the socket. Different techniques and guidance strategies are then shown with comments on the advantages and disadvantages of each one. The system consists of a standard electric wheelchair with an on-board computer, sensors and a graphic user interface run by the computer. On the other hand, this eye-control method can be applied to handle graphical interfaces, where the eye is used as a mouse computer. Results obtained show that this control technique could be useful in multiple applications, such as mobility and communication aid for handicapped persons.

Activities of Daily Living↗

PubMed2003

Chloride present in biological samples as a tool for enhancement of sensitivity in capillary zone electrophoretic analysis of anionic trace analytes.

Effects originating from the variability of the sample matrix can be efficiently eliminated when the separation conditions are selected so that compounds of like charge with high concentration referred to as macrocomponents are embodied into the system of transient isotachophoresis. For stacking and separation of anionic trace analytes in biological samples, the presence of chloride is shown to be important to balance out effects of other macrocomponents that act against isotachophoretic stacking. Having acetoacetate, malate, citrate, and some drug metabolites in untreated human serum samples, the stacking mechanism of these compounds in an electrolyte system comprising 5 mM mandelic acid and epsilon -aminocaproic acid, pH 3.8, is explained. Analytes are monitored by indirect UV-absorption detection. Attention is paid to the minimum chloride concentration required with respect to the concentration ratio of phosphate (stacker) and lactate (destacker) present in the sample so as to ensure both stacking and separation of trace analytes. Insight into the separation process is given both with computer simulations and experiments. For selected analytes, the effect of chloride concentration on quantitative evaluation, sensitivity and limit of detection is demonstrated as well. Moreover, the applicability of the mobility window between phosphate and lactate for an additional group of metabolites is sketched.

Anions↗

PubMed1999

Environmental hazards of mobile ground spraying with cyanophos and fenthion for quelea control in Senegal.

Seven roosts of red-billed quelea, Quelea quelea, in the Senegal River Valley and Delta were visited during and after aerial or terrestrial treatments with either Cyanox (cyanophos 500 g a.i. liter-1, five roosts) or Queletox (fenthion 640 g a.i. liter-1, two roosts). The primary goal of the observations was to provide data on environmental effects of cyanophos after mobile ground spraying operations. Twenty-six species of vertebrates (birds, reptile, fish) were found dead or debilitated near the spray sites. Effects on nontarget fauna were most pronounced among owls (cyanophos and fenthion) and blue-naped mousebirds, Urocolius macrourus (fenthion). Among terrestrial invertebrates ants and carabid, and tenebrionid beetles were the most conspicuously affected. Among aquatic invertebrates affected tadpole shrimps, Triops cancriformis, dominated. Extremely high residues were found immediately after spraying on tree leaves in the spillway of a vehicle-mounted Berthoud Super Puma airblast sprayer (up to 1380 mg kg-1) and on birds found dying under these trees (125-11,277 microg bird-1, average 2720 microg bird-1) in two roosts treated with cyanophos. Blue-naped mousebirds were identified as being particularly at risk. Side effects were not dose related. They were most severe after routinely practiced mobile ground spraying applications which led to overdosing. These application methods impose severe environmental hazards, and should be abandoned.

Animals↗

PubMed2005

Developing a Cyberinfrastructure for integrated assessments of environmental contaminants.

The objective of this study was to design and implement prototype software for capturing field data and automating the process for reporting and analyzing the distribution of mercury. The four phase process used to design, develop, deploy and evaluate the prototype software is described. Two different development strategies were used: (1) design of a mobile data collection application intended to capture field data in a meaningful format and automate transfer into user databases, followed by (2) a re-engineering of the original software to develop an integrated database environment with improved methods for aggregating and sharing data. Results demonstrated that innovative use of commercially available hardware and software components can lead to the development of an end-to-end digital cyberinfrastructure that captures, records, stores, transmits, compiles and integrates multi-source data as it relates to mercury.

Automation↗

PubMed2005

Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri.

Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd.

Arabidopsis↗

PubMed2004

The investigation of functional brain lateralization by transcranial Doppler sonography.

Functional transcranial Doppler sonography (fTCD) adds to the techniques of functional imaging. fTCD measures cerebral perfusion changes related to neural activation in a way comparable to functional magnetic resonance tomography. fTCD contends itself with comparison of averaged, event-related blood flow velocity changes within the territories of two cerebral arteries, for example the left versus the right middle cerebral artery. It can thus serve to evaluate the functional lateralization of higher cognitive functions like hemispheric language dominance (HLD). We present typical applications of fTCD by summarizing studies employing the technique. Then, the physical and physiological underpinnings of fTCD are reviewed. After a brief description of a prototype paradigm for assessing HLD, a detailed outline of the fTCD data analysis is presented. Caveats for fTCD, like other functional imaging techniques, are that the validity of results depends on adequate control of the task parameters, particularly cooperation and reference conditions. We complete the review with examinations of the reliability and validity of the fTCD technique. We conclude that fTCD can be employed to substitute the invasive amobarbital procedure to determine language lateralization in individual patients before undergoing brain surgery. Because of its easy applicability, robustness and mobility, fTCD can also be used to examine many subjects (including children) to obtain representative data on the variability of lateralization of higher cognitive functions, or to scan for atypical patterns of lateralization.

Algorithms↗

PubMed1998

Chromatographic separations of aromatic carboxylic acids.

The purpose of this review is to present methods of chromatographic analysis of aromatic carboxylic acids. The separation, identification and quantitative analysis of aromatic carboxylic acids are necessary because of their importance as non-steroid antiphlogistic drugs, semi-products of biosynthesis of aromatic amino-acids in plants (phenolic acids), metabolites of numerous toxic substances, drugs and catecholamines. HPLC separation of ionic samples tends to be more complicated than separation of non-ionic compounds. The review describes the dependence of the retention of ionic solutes on pH and solvent composition as well as on the ionic strength of a mobile phase. The application of the ion-suppressing RP-HPLC method using organic modifiers (aqueous buffer solutions) as eluents in aromatic carboxylic acid analysis is also presented. In more difficult cases of analysis the addition of an ion-pairing reagent, such as the quaternary alkylammonium ion, is necessary to obtain satisfactory separations. Hypotheses of ion-pair formation in reversed-phase systems as well as the influence of various agents on the separation of ionic solutes in IP-RP systems are explained. Examples of the application of ion-pair liquid chromatography to the analysis of aromatic carboxylic acids have also been reviewed. The principles and application of ion-exchange chromatography to the purification, isolation and less frequently, to chromatographic analysis are discussed. Polar adsorbents and polar bonded stationary phases are also widely used in carboxylic acid separation in normal-phase systems, mainly by TLC, often coupled with densitometry. The review also shows examples of separation of chiral benzoic acids and their derivatives in LC systems. The possibilities of application of gas chromatography preceded by derivatisation or pyrolysis of acidic compounds and applications of GC-MS and Py-GC-MS coupled methods in identification and quantitation of aromatic carboxylic acids is also reviewed.

Carboxylic Acids↗

PubMed2001

A capillary-based supersonic jet inlet system for resonance-enhanced laser ionization mass spectrometry: principle and first on-line process analytical applications.

A new supersonic jet inlet system for resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS), based on a fused-silica capillary with an integral nozzle has been developed. The new jet inlet system generates a supersonic molecular beam that originates in the center of the ion source of the time-of-flight mass spectrometer. Because of the design of the inlet system, high spatial overlap of sample and laser beam (i.e., increased detection sensitivity) and excellent jet beam qualities are achieved with good adiabatic cooling properties of analyte molecules (i.e., considerably enhanced optical selectivity of the REMPI process). Furthermore, the inlet is very robust and chemically inert and contains no moving parts. As a result of these properties, the new inlet is perfectly suited for field applications of jet-REMPI. A first field application of a mobile supersonic jet-REMPI mass spectrometer equipped with the novel inlet technique is reported; namely, the concentration of monochlorobenzene, which is an indicator for the formation and emission of toxic polychlorinated dibenzo-p-dioxins/furans, PCDD/F) was measured on-line in the flue gas of a waste incineration plant.

Journal Article↗

PubMed1997

Evidence that up-regulation of the parotid Na(+)-K(+)-2Cl- cotransporter by hypertonic shrinkage is not duplicated by isotonic shrinkage.

The application of Ca2+ mobilizing secretagogues to rat parotid acini results in a significant decrease in cell volume (15-30%) due to isotonic salt loss. It is often assumed that the effects of such an isotonic volume decrease can be mimicked by anisotonic cell shrinkage. We demonstrate that the Na(+)-K(+)-2Cl- cotransporter in these cells is up-regulated by Ca2+ mobilizing secretagogues as well as by cell shrinkage in hypertonic media. However, we find that although the protein kinase inhibitors staurosporine (0.3 microM) and K252a (0.6 microM) significantly blunt the latter up-regulation, they are without effect on the former. These observations suggest that hypertonic and isotonic shrinkage do not result in the activation of the same intracellular signalling pathways, and indicate that anisotonic volume perturbations may not provide good experimental models of physiologic isotonic volume changes.

Ammonium Chloride↗

PubMed2002

Interaction of the cardiovascular system with an implanted rotary assist device: simulation study with a refined computer model.

In recent years, implanted rotary pumps have achieved the level of extended clinical application including complete mobilization and physical exercise of the recipients. A computer model was developed to study the interaction between a continuous-flow pump and the recovering cardiovascular system, the effects of changing pre- and afterloads, and the possibilities for indirect estimation of hemodynamic parameters and pump control. A numerical model of the cardiovascular system using Matlab Simulink simulation software was established. Data of circulatory system modules were derived from patients, our own in vitro and in vivo experiments, and the literature. Special care was taken to simulate properly the dynamic pressure-volume characteristics of both left and right ventricle, the Frank-Starling behavior, and the impedance of the proximal vessels. Excellent correlation with measured data was achieved including pressure and flow patterns within the time domain, response to varying loads, and effects of previously observed pressure-flow hysteresis in rotary pumps. Potential energy, external work, pressure-volume area, and other derived heart work parameters could be calculated. The model offers the possibility to perform parameter variations to study the effects of changing patient condition and therapy and to display them with three-dimensional graphics (demonstrated with the effects on right ventricular work and efficiency). The presented model gives an improved understanding of the interaction between the pump and both ventricles. It can be used for the investigation of various clinical and control questions in normal and pathological conditions of the left ventricular assist device recipient.

Computer Simulation↗

PubMed1995

Consumer participation in identifying research and development priorities for power wheelchair input devices and controllers.

A focus group comprised of persons who use power wheelchairs and professionals working in the field were asked to participate in a brainstorming session to determine priorities for the development and application of power mobility input devices and control concepts. The group consensus was that durability and reliability are the most important criteria. Essentially, the expectation is that a power wheelchair must work everyday in the way a person needs it and wants it. At the same time, there is a desire to enhance and advance the features of input devices and control systems. Many would say these changes constitute designing "smarter" power wheelchairs, such as systems that can independently detect obstacles and can provide users with more feedback. This paper presents the rationale behind forming this focus group and details of the results of a brainstorming session where ideas were generated and prioritized. The five most important issues as determined by the group are discussed in depth.

Community Participation↗

PubMed2003

Efficient charge recovery method for driving piezoelectric actuators with quasi-square waves.

In this paper, an efficient charge recovery method for driving piezoelectric actuators with low frequency square waves in low-power applications such as mobile microrobots is investigated. Efficiency issues related to periodic mechanical work of the actuators and the relationship among the driving electronics efficiency, the piezoelectric coupling factor, and the actuator energy transmission coefficient are discussed. The proposed charge recovery method exploiting the energy transfer between an inductor and a general capacitive load is compared with existing techniques that lead to inherent inefficiencies. A charge recovery method is then applied to piezoelectric actuators, especially to bimorph ones. Unitary efficiency can be obtained theoretically for purely capacitive loads while intrinsic losses such as hysteresis necessarily lower the efficiency. In order to show the validity of the method, a prototype driving electronics consisting of an extended H-bridge is constructed and tested by experiments and simulations. Preliminary results show that 75% of charge (i.e., more than 56% of energy) can be recovered for bending actuators such as bimorphs without any component optimization at low fields.

Journal Article↗

PubMed2006

Extracellular ATP stimulates exocytosis via localized Ca(2+) release from acidic stores in rat pancreatic beta cells.

Three different methods, membrane capacitance (C(m)) measurement, amperometry and FM dye labeling were used to investigate the role of extracellular ATP in insulin secretion from rat pancreatic beta cells. We found that extracellular application of ATP mobilized intracellular Ca(2+) stores and synchronously triggered vigorous exocytosis. No influence of ATP on the readily releasable pool of vesicles was observed, which argues against a direct modulation of the secretory machinery at a level downstream of Ca(2+) elevation. The stimulatory effects of ATP were greatly reduced by intracellular perfusion of BAPTA but not EGTA, suggesting a close spatial association of fusion sites with intracellular Ca(2+) releasing sites. ATP-induced Ca(2+) transients and exocytosis were not blocked by thapsigargin (TG), by a ryanodine receptor antagonist or by dissipation of pH in acidic stores by monensin alone, but they were greatly attenuated by IP(3) receptor inhibition as well as ionomycin plus monensin, suggesting involvement of IP(3)-sensitive acidic Ca(2+) stores. Taken together, our data suggest that extracellular ATP triggers exocytosis by mobilizing spatially limited acidic Ca(2+) stores through IP(3) receptors. This mechanism may explain how insulin secretion from the pancreas is coordinated through diffusible ATP that is co-released with insulin.

Adenosine Triphosphate↗

PubMed1989

Two calcium-activated chloride conductances in Xenopus laevis oocytes permeabilized with the ionophore A23187.

1. Currents evoked by elevated intracellular free Ca2+ in Xenopus laevis oocytes were studied using the two-electrode voltage clamp technique. The elevation in Ca2+ concentration was achieved in three ways: by the use of the divalent cation ionophore A23187; by application of Ca2+-mobilizing neurotransmitters serotonin and acetylcholine (ACh); by the entry of Ca2+ through voltage-dependent channels. 2. In most experiments, the membrane was permeabilized to Ca2+ by a 15 min pretreatment with A23187 in a Ca2+-free solution. Exposure of the ionophore-treated oocytes to external Ca2+ elicited an inward current (at holding potentials of -40 to -60 mV). At external Ca2+ concentrations ([Ca2+]) between 0.1 and 1 mM, the current had a time-to-peak of at least 10 s, and slowly decayed over tens of seconds. At [Ca2+] greater than 2 mM, the inward current had two distinct kinetic components, a fast and transient one (Ifast) and a slow one (Islow). 3. The main carrier of the Ca2+-evoked inward current was Cl-. Several data indicate the existence of a tetraethylammonium (TEA)-sensitive K+ conductance. No evidence for a Na+ current was found. 4. The two components of the Ca2+-evoked inward current in ionophore-permeabilized oocytes, and the two components of the current evoked by ACh and serotonin (the latter in oocytes injected with rat brain RNA but untreated with A23187), were blocked by intracellular injection of the Ca2+ chelator, ethyleneglycolbis-(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid (EGTA). The two components of these currents displayed different sensitivity to Ca2+ buffering; higher doses of EGTA were necessary to inhibit the slow component than the fast one. 5. One to two minutes of treatment with 2 mM-9-anthracene carboxylic acid (9-AC) fully blocked Ca2+-dependent Cl- current evoked by Ca2+ influx through voltage- dependent Ca2+ channels in intact (untreated with A23187) oocytes. In ionophore-treated oocytes, block of Ifast was observed at holding potentials at which the current was outward (i.e. due to Cl- influx); Islow was inhibited only partially. The block of Ca2+-evoked Cl- efflux by 9-AC developed much more slowly and was less potent. to explain these results, the existence of two sites of 9-AC action is proposed. 6. Exposure of the ionophore-permeabilized oocytes to 0.1-0.2 mM [Ca2+] strongly reduced the response to higher concentrations of Ca2+. Ifast displayed stronger Ca2+-dependent inactivation than Islow.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗