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PubMed1992

[Liver biopsy in suspected alcoholic liver damage].

Alcohol can induce a wide spectrum of histological changes in the liver. Three morphologic patterns of alcoholic liver injury are now generally accepted, i.e. fatty change, alcoholic hepatitis and alcoholic cirrhosis, but a broad array of lesions has been added to this list in recent years. These damage patterns differ considerably in their significance as to indication and diagnostic power of liver biopsies. Liver biopsy is recommended in patients with clinically suspected alcoholic liver disease for diagnostic and prognostic reasons. Moreover, clinicians want to exclude nonalcoholic liver diseases that might otherwise be missed. Alcoholic hepatitis, which is associated with increased morbidity and mortality, has the highest degree of diagnostic specificity in biopsies, because its features are well-defined and are mimicked by a rather small group of other causes. When associated with perivenular and pericellular fibrosis, it may provide prognostic parameters. In contrast, fatty liver, which may be induced by alcohol as well as other etiologies, usually does not need liver biopsy, with some exceptions. It may lead to cholestasis severe enough to mimic obstructive jaundice, or may result in abnormal imaging studies suggesting metastases. Verification of histological findings may be important when these circumstances arise. Cirrhosis is easily verified in biopsies of appropriate quality; however, advanced cirrhosis is a morphologically nonspecific alteration, because cirrhotic tissue patterns converge irrespective of their cause. Liver biopsy may help to identify nonalcoholic liver disease in patients suspected of harboring alcoholic liver disease. In fact, up to 20% of biopsies may show other, potentially treatable disorders, thus extending the indication for liver biopsy in situations of complex clinical and laboratory patterns.

Biopsy, Needle↗
PubMed1996

A global verification study of a quasi-static knee model with multi-bundle ligaments.

The ligaments of the knee consist of fiber bundles with variable orientations, lengths and mechanical properties. In concept, however, these structures were too often seen as homogeneous structures, which are either stretched or slack during knee motions. In previous studies, we proposed a new structural concept of the ligaments of the knee. In this concept, the ligaments were considered as multi-bundle structures, with nonuniform mechanical properties and zero force lengths. The purpose of the present study was to verify this new concept. For this purpose, laxity characteristics of a human knee joint were compared as measured in an experiment and predicted in a model simulation study. In the experiment, the varus-valgus and anterior-posterior laxities of a knee-joint specimen containing the ligaments and the articular surfaces only, were determined. From this knee-joint, geometric and mechanical parameters were derived to supply the parameters for a three-dimensional quasi-static knee-joint model. These parameters included (i) the three-dimensional insertion points of bundles, defined in the four major knee ligaments, (ii) the mechanical properties of these ligament, as functions of their relative insertion orientations and (iii) three-dimensional representations of the articular surfaces. With this model the experiments were simulated. If knee-model predictions and experimental results agree, then the multi-bundle ligament models are validated, at least with respect to their functional role in anterior-posterior and varus-valgus loading of the joint. The model described the laxity characteristics in AP-translation and VV-rotation of the cadaveric knee-joint specimen reasonably well. Both display the same patterns of laxity changes during knee flexion. Only if a varus moment of 8 N m was applied and if the tibia was posteriorly loaded, did the model predict a slightly higher laxity than that measured experimentally. From the model-experiment comparisons it was concluded that the proposed structural representations of the ligaments and their mechanical property distributions seem to be valid for studying the anterior-posterior and varus-valgus laxity characteristics of the human knee-joint.

Biomechanical Phenomena↗
PubMed2000

Current role of platelet glycoprotein IIb/IIIa inhibitors in acute coronary syndromes.

CONTEXT: The central role of platelet-rich thrombus in the pathogenesis of acute coronary syndromes (ACSs) is well-known. Glycoprotein IIb/IIIa (Gp IIb/IIIa) receptor antagonists are potent inhibitors of platelet function that may be expected to affect favorably the natural history of ACSs. OBJECTIVE: To define the optimal role of Gp IIb/IIIa inhibitors in treatment strategies for ACSs. DATA SOURCES: A MEDLINE search was performed to identify all English-language articles regarding use of Gp IIb/IIIa inhibitors in ACSs published between 1966 and June 2000. In addition, relevant abstracts from the annual meetings of the American Heart Association, American College of Cardiology, and the European Society of Cardiology were reviewed. STUDY SELECTION: Only studies of 500 or more patients were included. Of 15 studies identified, 10 randomized, placebo-controlled, double-blind trials of Gp IIb/IIIa inhibitors in ACSs were selected for review. DATA EXTRACTION: Data quality was determined by publication in the peer-reviewed literature or presentation at an official cardiology society-sponsored meeting, as well as by verification with the primary author. DATA SYNTHESIS: Three members of this class of drugs are available for intravenous use. Abciximab, eptifibatide, and tirofiban hydrochloride, each have data demonstrating their value in improving the outcomes of patients presenting with ACSs. Current evidence supports use of these drugs in both conservative and invasive treatment strategies. Glycoprotein IIb/IIIa-blocking therapy is safe, and with proper precautions, bleeding risks can be minimized. Biological differences exist among these agents, but as of yet, no head-to-head comparisons have been made of their clinical efficacy. Unlike intravenous Gp IIb/IIIa inhibitors, available data regarding any role of oral Gp IIb/IIIa inhibitors are not favorable. CONCLUSION: Current data indicate that intravenous Gp IIb/IIIa inhibitor therapy merits a prominent role in the initial management of patients with ACSs. JAMA. 2000;284:1549-1558.

Abciximab↗
PubMed1994

Characterization of recombinant proteins: biochemical and biophysical criteria for the identity of native and renatured human tissue plasminogen activator and its mutants.

Rapid progress in recombinant DNA techniques has led to the production of a great variety of native and modified proteins in bacteria which, however, frequently occur in non-native conformations or in aggregated form. Renaturation methods must necessarily include criteria for the confirmation of the native structure and function of the refolded macromolecules. This Review describes some of the spectroscopic and thermodynamic techniques which can provide powerful tests for the identity of native and renatured proteins. Emphasis was laid on the concentration requirements of the methods and on the ease of application and availability of instrumentation. As an example we used the single-chain recombinant tissue plasminogen activator (rt-PA) at different pH values and buffer systems. t-PA is a monomeric serine proteinase of M(r) 68,000 that converts plasminogen into plasmin, thereby promoting the degradation of the fibrin network. This enzyme is a promising candidate for thrombolytic therapy of acute myocardial infarction. On the basis of the cDNA sequence the 527 amino acids of t-PA are likely to occur in five distinct structural domains. Specifically we exemplify the application of microcalorimetric studies for the verification of structural identity on rt-PA.

Amino Acid Sequence↗
PubMed2006

Extracting biochemical parameters for cellular modeling: A mean-field approach.

Recent developments in molecular biology have made it feasible to carry out experimental verification of mathematical models for biochemical processes, offering the eventual prospect of creating a detailed, validated picture of gene expression. A persistent difficulty with this long-term goal is the incompleteness of the kinetic information available in the literature: Many rate constants cannot or have not yet been measured. Here, we present a method of filling in missing parameters using an approach conceptually analogous to mean-field approaches in statistical mechanics: When studying a particular gene, we extract key parameters by considering the averaged effect of all other genes in the system, analogously to considering the averaged magnetic field in a physical spin model. This methodology has been applied to account for the effect of the presence of the Escherichia coli genome on the availability of key enzymes involved in gene expression (RNA polymerases and ribosomes), yielding the number of free enzymes as a function of cellular growth rate. These conclusions have been obtained by deriving genome-wide averages and matching them to bulk literature values of E. coli K-12 and B/r. Average rate constants have been found for RNA polymerases and ribosomes binding to promoter and ribosome-binding sites, respectively; these results suggest that cells vary not only their production rates of RNA polymerase and ribosomes under different growth-rate conditions but also change their global level of transcriptional/translational activation and repression, thus altering the average binding rate constants for these enzymes. To test the mean-field method, the results from the genome-wide averages have been applied to the induced lac operon, where our derived on-rate for binding of RNA polymerase to the promoter is in good agreement with previous experimental results.

Computer Simulation↗
PubMed2006

Lymphocytic choriomeningitis virus mx strain does not induce the expression of tumor-associated carbonic anhydrase IX in persistently infected HeLa cells.

Summary. - Lymphocytic choriomeningitis virus (LCMV) is an arenavirus that readily causes persistent infections, in which it does not interfere with vital functions of the cells, but can affect expression of "luxurious" genes. MX strain of LCMV (MX LCMV) has been identified as an agent transmissible by cell-to-cell contact in the human carcinoma MaTu cells grown in a mixed culture with HeLa cells. When compared to uninfected HeLa, the MaTu-MX-infected HeLa cells, to which the virus was transmitted via co-cultivation with mitomycin C-treated MaTu cells, showed an elevated expression of a protein called MN, suggesting that MN can be induced by MX LCMV. MN protein was later identified as the carbonic anhydrase isoform IX (CA IX), whose expression has been predominantly associated with hypoxic tumors of poor prognosis. Since the proposal that MX LCMV can induce such a cancer-related protein could substantially change our view on the biology of LCMV-host interaction we undertook its verification. Instead of co-cultivation, we used MaTu cell-free extracts to transmit MX LCMV to HeLa cells. These cells were then grown for more than 30 passages, but the level of MN/CA IX did not increase throughout the whole cultivation period as compared to uninfected HeLa cells. Moreover, a treatment of MaTu-MX-infected HeLa cells with ribavirin eliminated the virus, but did not reduce the MN/CA IX expression. Our results clearly showed that MN/CA IX is independent of MX LCMV and that the virus itself does not influence the MN/CA IX level in HeLa cells.

Antigens, Neoplasm↗
PubMed2007

Photoionization affected by chemical anisotropy.

The kinetic constants of rhodamine 3B quenching by N,N-dimethyl aniline were extracted from the very beginning of the quenching kinetics, recently studied in a few solvents of different viscosities. They were well fitted with the conventional kinetic constant definition, provided the radial distribution function of simple liquids was ascribed to the reactant pair distribution and the contact electron transfer rate was different in all the cases. This difference was attributed to the chemical anisotropy averaging by the rotation of reactants, which is the faster in solvents of lower viscosity. With the proper choice of a space dependent encounter diffusion, the whole quenching kinetics was well fitted with an encounter theory, using the Marcus [J. Chem. Phys. 24, 966 (1956); 43, 679 (1965)] transfer rate instead of the contact Collins-Kimball [J. Colloid. Sci. 4, 425 (1949)] approximation. Not only the beginning and middle part of the quenching were equally well fitted, but the long time (Markovian) rate constant was also found to be the same as previously obtained. Moreover, the concentration dependencies of the fluorescence quantum yield and the Stern-Volmer constant were specified and await their experimental verification.

Journal Article↗
PubMed2006

Phylogenetically widespread alternative splicing at unusual GYNGYN donors.

BACKGROUND: Splice donor sites have a highly conserved GT or GC dinucleotide and an extended intronic consensus sequence GTRAGT that reflects the sequence complementarity to the U1 snRNA. Here, we focus on unusual donor sites with the motif GYNGYN (Y stands for C or T; N stands for A, C, G, or T). RESULTS: While only one GY functions as a splice donor for the majority of these splice sites in human, we provide computational and experimental evidence that 110 (1.3%) allow alternative splicing at both GY donors. The resulting splice forms differ in only three nucleotides, which results mostly in the insertion/deletion of one amino acid. However, we also report the insertion of a stop codon in four cases. Investigating what distinguishes alternatively from not alternatively spliced GYNGYN donors, we found differences in the binding to U1 snRNA, a strong correlation between U1 snRNA binding strength and the preferred donor, over-represented sequence motifs in the adjacent introns, and a higher conservation of the exonic and intronic flanks between human and mouse. Extending our genome-wide analysis to seven other eukaryotic species, we found alternatively spliced GYNGYN donors in all species from mouse to Caenorhabditis elegans and even in Arabidopsis thaliana. Experimental verification of a conserved GTAGTT donor of the STAT3 gene in human and mouse reveals a remarkably similar ratio of alternatively spliced transcripts in both species. CONCLUSION: In contrast to alternative splicing in general, GYNGYN donors in addition to NAGNAG acceptors enable subtle protein variations.

Alternative Splicing↗
PubMed1978

[Reproducibility of bronchial provocative testing in bronchitis (author's transl)].

Bronchial reactivity was examined every 3 month in a follow-up study of 40 subjects mostly showing chronic nonspecific lung disease and all having bronchial hyperreactivity at the beginning of the study. Only 7 of them (17.5%) had constant hyperreactivity for the time of observation. There has been parallelism between test results and complaints in 72% of patients with chronic bronchitis and in 65.2% of the second group (mostly subjects with bronchitis). Seasons had no strong influence on bronchial reactivity. Bronchial provocative testing has proved as a valuabel method for verification of obstructive complaints. The test results shouldn't be interpreted without regarding clinical data. Using as a screening test a more detailed diagnostic and follow-up are necessary to avoid false and premature consequences. As to expert opinions and decisions on compensation the test results can correctly be interpreted only if reproducibility in the single case has been proved and if they are in agreement with the clinical signs and symptoms of the case.

Acetylcholine↗
PubMed1998

H-NS regulates DNA repair in Shigella.

We report a new role for H-NS in Shigella spp.: suppression of repair of DNA damage after UV irradiation. H-NS-mediated suppression of virulence gene expression is thermoregulated in Shigella, being functional at 30 degrees C and nonfunctional at 37 to 40 degrees C. We find that H-NS-mediated suppression of DNA repair after UV irradiation is also thermoregulated. Thus, Shigella flexneri M90T, incubated at 37 or 40 degrees C postirradiation, shows up to 30-fold higher survival than when incubated at 30 degrees C postirradiation. The hns mutants BS189 and BS208, both of which lack functional H-NS, show a high rate of survival (no repression) whether incubated at 30 or 40 degrees C postirradiation. Suppression of DNA repair by H-NS is not mediated through genes on the invasion plasmid of S. flexneri M90T, since BS176, cured of plasmid, behaves identically to the parental M90T. Thus, in Shigella the nonfunctionality of H-NS permits enhanced DNA repair at temperatures encountered in the human host. However, pathogenic Escherichia coli strains (enteroinvasive and enterohemorrhagic E. coli) show low survival whether incubated at 30 or 40 degrees C postirradiation. E. coli K-12 shows markedly different behavior; high survival postirradiation at both 30 and 40 degrees C. These K-12 strains were originally selected from E. coli organisms subjected to both UV and X irradiation. Therefore, our data suggest that repair processes, extensively described for laboratory strains of E. coli, require experimental verification in pathogenic strains which were not adapted to irradiation.

Bacterial Proteins↗
PubMed1977

Thermal properties of human skin related to nondestructive measurement of epidermal thickness.

The thermal and physical properties of skin are reviewed briefly in the light of their relationship to skin functions and their influence on temperature measurement and related methodology. Thermal conductivity and epidermal thickness have a direct bearing on the majority of skin functions as these significantly affect heating rates, thermal pain thresholds, and blister formation, as will be seen from the experimental data. The accumulated data on both temperature and pain threshold are used to estimate epidermal thickness in the intact individual. The procedure to accomplish this end utilizes the measured thermal pain threshold, surface temperature, exposure time, and incident energy on a standardized skin site (volar surface of the forearm) to obtain conductivity values. These values are then used in a two-layer system heat flow equation to determine epidermal thickness in other skin sites (fingers) referred to the standard area. Systematic exposures to various materials at high temperatures in contact-burn studies provide data for checking the reliability of this procedure by alternative computations and comparison with predicted tissue temperatures derived from earlier work. Certainly, blister formation and physical measurement of the excised epidermis would provide direct verification of the accuracy of the procedure but these measures have not been undertaken. It is quite possible that over a period of time verification data could be accumulated incidentally in the clinic where skin grafting procedures are carried out. For this purpose only relatively simple measurements of skin temperature and pain threshold, as described herein, would be required to be performed on skin graft donors to provide epidermal thickness measurements for comparison with direct measurements of excised skin immediately after removal.

Fingers↗
PubMed2000

[Neuropsychological syndromes of arteriovenous malformation of cinguli gyrus and hippocampus].

41 patients with arteriovenous malformations (AVM) of gyrus cinguli and 39 ones with AVM of hippocamp were examined. AVM verification was performed according to the data of angiography and computer tomography of the brain during the operation. 4 patients had generalized tonic-clonic seizures and absans. In these cases AVM spread from gyrus cinguli and hippocamp to the cortical medio-basal regions of frontal and temporal lobes of the brain. Autonomic paroxysms weren't found in the patients. Before the operation 73 patients had disorders of memory that progressed after the operation. Disorders of memory weren't completely identical in damages of gyrus cinguli or of hippocamp, namely: in damages of gyrus cinguli such disorders were similar in terms of their characteristics with those observed in damages of medio-basal regions of the frontal lobes, while in pathology of hippocamp--with those of diencephalic region (region of III ventricle). A conclusion was made about different participation of the structures studied in realization of the memory function.

Cerebral Angiography↗
PubMed2004

Application of AgaR repressor and dominant repressor variants for verification of a gene cluster involved in N-acetylgalactosamine metabolism in Escherichia coli K-12.

The agaZVWEFASYBCDI gene cluster encodes the phosphotransferase systems and enzymes responsible for the uptake and metabolism of N-acetylgalactosamine and galactosamine in Escherichia coli. In some strains of E. coli, particularly the common K-12 strain, a portion of this cluster is missing because of a site-specific recombination event that occurred between sites in agaW and agaA. Strains that have undergone this recombination event have lost the ability to utilize either N-acetylgalactosamine or galactosamine as sole sources of carbon. Divergently transcribed from this gene cluster is the gene agaR encoding a transcriptional repressor belonging to the DeoR/GlpR family of transcriptional regulators. Promoters upstream of agaR, agaZ and agaS were characterized. All three promoters had elevated activity in the presence of N-acetylgalactosamine or galactosamine, were regulated in vivo by AgaR and possessed specific DNA-binding sites for AgaR upstream from the start sites of transcription as determined by DNase I footprinting. In vivo analysis and DNase I footprinting indicated that the promoter specific for agaZ also requires activation by cAMP-CRP. Previous work with GlpR and other members of the DeoR/GlpR family have identified highly conserved amino acid residues that function in DNA-binding or response to inducer. These residues of AgaR were targeted for site-directed mutagenesis and yielded variants of AgaR that were either negatively dominant or non-inducible. The apparent ability to produce negatively dominant and non-inducible variants of proteins of the DeoR/GlpR family of currently unknown function will likely facilitate screening for function.

Acetylgalactosamine↗
PubMed1996

Cloning, sequencing and proposed structure for a prostaglandin F2 alpha receptor regulatory protein.

The cDNA has been cloned for a protein which copurifies with and colocalizes with [3H]PGF2 alpha binding activity, yet differs from the previously cloned prostaglandin F2 alpha receptor. Polyclonal antibody, produced against one of two protein bands present in a highly purified preparation of [3H]PGF2 alpha binding activity isolated from pregnant bovine corpus luteum, was used to screen a rat ovary cDNA expression library. A single strongly positive clone was identified containing a 4 kilobase (kb) insert. Northern analysis using this cDNA as a probe revealed the expression of a 6 kb mRNA with a tissue distribution similar to that seen by immunohistochemical analysis with the polyclonal antibody. Tissues possessing the largest quantity of the protein's mRNA are reproductive tissues, lung, and heart. Directed cDNA synthesis was required to clone the 5' end of the cDNA. Verification that the correct cDNA was cloned is provided by alignment of the predicted protein's mature amino terminal amino acid sequence with sequence observed by protein sequencing. Translation of the predicted 879 amino acid open reading frame (ORF) suggests a protein structure exhibiting six glycosylated immunoglobulin type loops, one of which may either be membrane associated or may be the site of association with another protein, a transmembrane region, and a short, highly charged, carboxy terminal cytoplasmic tail. Based upon searches of the NIH and EMBL protein databanks, this is a unique protein. The FPRP mRNA is notable for a highly structured G,C rich 5' end and over 3 kb of 3' untranslated region (UTR) that includes 7 ATTTA 'destabilization sequences' and an 'inflammatory mediator'-like sequence. These characteristic sequences in the 3' UTR suggest that the mRNA is tightly regulated and may code for a protein that is functionally related to an inflammatory mediator. Functional studies in the accompanying report suggest a negative regulatory function for this protein. We suggest the name prostaglandin F2 alpha receptor regulatory protein (FPRP).

Amino Acid Sequence↗
PubMed2006

Modulation of respiratory pattern and upper airway muscle activity by the pedunculopontine tegmentum: role of NMDA receptors.

The pedunculopontine tegmental nucleus (PPT) is postulated to have important functions relevant to the regulation of rapid eye movement (REM) sleep and arousal, and various motor control systems including respiration. We have recently shown that pharmacologic activation of a neuronal subpopulation within the PPT, induced by micropipette injection of glutamate in nanoliter volumes, can produce respiratory rhythm disturbances and changes in genioglossus muscle activity in anesthetized rats. The aim of this study was to determine whether the respiratory pattern disturbance and increased genioglossus muscle tone induced by glutamate injection within the PPT are mediated by activation of N-methyl-D-aspartate (NMDA) receptors within the PPT. Experiments were performed in eight adult male spontaneously breathing Sprague-Dawley rats anesthetized using nembutal. Respiratory movements were monitored by piezoelectric strain gauge. Three-barrel glass pipettes were used to pressure inject glutamate (as a probe for respiratory modulating sites), ketamine (an NMDA channel blocker), and oil-red dye (to aid in histological verification of the injection sites) within the PPT. Electroencephalograms were recorded from the sensorimotor cortex, the hippocampus, and the pons, contralateral to the injection site. Electromyograms (EMGs) were recorded from the genioglossus muscle. The typical response to glutamate injection within the PPT respiratory-modulating region was immediate apnea followed by tachypnea and increased genioglossal tonic activity. The noncompetitive NMDA receptor channel-antagonist ketamine, injected at the same site and in the same volume as glutamate (5 nl), blocked respiratory dysrhythmia and genioglossal EMG responses to subsequent glutamate injections. For the first time, the present results suggest that respiratory rhythm and upper airway muscle tone are controlled by the activation of pedunculopontine tegmental nucleus NMDA receptors.

Animals↗
PubMed1989

Exercise tolerance in chronic obstructive pulmonary disease: importance of active and passive components of the ventilatory system.

We investigated which components of ventilatory function are related to exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. Physical characteristics, usual lung function, timing and neuromuscular components of ventilation were measured in 113 outpatients in whom FEV1/VC was less than 75% of the predicted value and exercise was limited by breathlessness. These variables were used to predict the maximum work load during progressive bicycle exercise. The prediction was obtained using a stepwise procedure in men and women separately. Among the variables selected, age, body weight, FEV1/VC, PImax, and P0.1/VT/TI accounted for 79% of the variability in maximum performance in men. The predictive model was statistically verified and was stable. The mean prediction error was 12 Watts. Among these variables, P0.1/VT/TI, PImax, and FEV1/VC were the main determinants of maximum work load (MWL). These results show that exercise limitation in COPD is related to impairment of both the active (inspiratory muscles) and passive (respiratory impedance) components of the ventilatory system. The same conclusions concerning passive components are proposed for women, despite a smaller population which prevented verification of the prediction.

Adult↗
PubMed1984

A technique for the detection, decomposition and analysis of the EMG signal.

In the present paper we have described a system for acquiring, processing and decomposing EMG signals for the purpose of extracting as many motor unit action potential trains as possible with the greatest level of accuracy. This system consists of 4 main sections. The first section consists of methodologies for signal acquisition and quality verification. Three channels of EMG signals are acquired using a quadripolar needle electrode designed to enhance discrimination among different MUAPs. An automated experiment control system is devised to free the experimenter from the burden of experiment detailed surveillance and bookkeeping; and to allow on-line assessment of the EMG signal quality in terms of decomposition suitability. The second section consists of methodologies for signal sampling and conditioning. The EMG signal is bandpass filtered (between 1 kHz and 10 kHz), sampled and compressed by eliminating parts of the signal under a preset threshold level. The third section consists of a signal decomposition technique where motor unit action potential trains are extracted from the EMG signal using a highly computer assisted interactive algorithm. The algorithm uses a continuously updated template matching routine and firing statistics to identify MUAPs in the EMG signal. The templates of the MUAPs are continuously updated to enable the algorithm to function even when the shape of a specific MUAP undergoes slow variations. The fourth section deals with ways in which to analyze and display the results. The more frequently used representation formats are: (1) display of MUAP wave shapes; (2) impulse trains representing motor unit firings; (3) IPI plots where time interval between successive firings of the same motor unit is plotted vs. time of the muscle contraction; (4) firing rate plots where the estimated time-varying mean firing rate of the detected motor units is plotted vs. time of the muscle contraction. The performance of the system has been tested in terms of: (1) consistency among results obtained by different operators; (2) accuracy evaluated on synthetic EMG signal; (3) indirect measure of accuracy on real EMG signal by comparing results pertaining the same motor unit action potential trains derived by two EMG signals, independently and simultaneously recorded from two different electrodes.

Action Potentials↗
PubMed2006

Analysis of the roles of FlgP and FlgQ in flagellar motility of Campylobacter jejuni.

Flagellar motility is an important determinant of Campylobacter jejuni that is required for promoting interactions with various hosts to promote gastroenteritis in humans or commensal colonization of many animals. In a previous study, we identified a nonmotile mutant of C. jejuni 81-176 with a transposon insertion in Cj1026c, but verification of the role of the encoded protein in motility was not determined. In this study, we have determined that Cj1026c and the gene immediately downstream, Cj1025c (here annotated as flgP and flgQ, respectively), are both required for motility of C. jejuni but not for flagellar biosynthesis. FlgP and FlgQ are not components of the transcriptional regulatory cascades to activate sigma(28)- or sigma(54)-dependent expression of flagellar genes. In addition, expression of flgP and flgQ is not largely dependent on sigma(28) or sigma(54). Immunblot analyses revealed that the majority of FlgP in C. jejuni is associated with the outer membrane. However, in the absence of FlgQ, the amounts of FlgP in the outer membrane of C. jejuni are greatly reduced, suggesting that FlgQ may be required for localization or stability of FlgP at this location. This study provides insight into features of FlgP and FlgQ, two proteins with previously undefined functions that are required for the larger, multicomponent flagellar system of C. jejuni that is necessary for motility.

Bacterial Outer Membrane Proteins↗