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Biomedical subjects

E Voss

Publications and source records attributed to E Voss.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Diagnosis of phlebothrombosis using color-coded duplex sonography. A prospective comparison with phlebography].

In a prospective study the reliability of colour-coded duplex-sonography (CCDS) and phlebography in the diagnosis of deep leg and pelvic vein thrombosis was compared. In 82 consecutive in- or out-patients (42 men, 40 women; mean age 53 [19-86] years) with clinically suspected leg or pelvic vein thrombosis the results of 275 phlebographies (reference method) and 275 CCDS were compared on admission and during follow-up. The two methods were performed less than 6 hours apart. In the diagnosis of thrombosis the sensitivity of CCDS was 99%, specificity 80%. In 88% of all tests, the different thrombosis levels, as diagnosed by phlebography, were also demonstrated by CCDS. These data indicate that, if the clinical picture of suspected deep leg or pelvic vein thrombosis is unclear, CCDS should be done first. Phlebography should be performed only if the results of the former are inconclusive.

Adult↗
PubMed1993

In vitro production of toxin-coregulated pili by Vibrio cholerae El Tor.

Toxin-coregulated pili (TCP) have been shown to be a virulence determinant and protective antigen for Vibrio cholerae strains of classical biotype, but their role in infection by strains of the alternative El Tor biotype remains uncertain. In an attempt to demonstrate TCP production by El Tor vibrios we have over-expressed the El Tor tcpA gene in Escherichia coli, in order to prepare a biotype-specific anti-TcpA serum. This reagent proved to be a very sensitive indicator of TcpA production in immunoblotting studies, but failed to detect polymerized pili on the bacterial surface by immuno-electron microscopy (IEM). However, results with an analogous reagent which detects classical TcpA suggested that antisera to unprocessed TcpA do not efficiently recognize epitopes on native proteins. Accordingly we prepared a serum against a cell envelope fraction rich in processed El Tor TcpA. After extensive absorption this reagent reacted almost exclusively with TcpA by immunoblotting; when used in IEM, it allowed visualization of typical TCP bundles on the surfaces of each of five El Tor strains known to produce TcpA in vitro. We have previously reported that the El Tor strain O17 does not synthesize TcpA during growth in vitro, but that an O17 clone carrying a cosmid of classical origin expresses surface TCP. Using the biotype-specific anti-TcpA reagents in immunoblotting studies it has been possible to detect the product of the host chromosomal tcpA gene in such constructs; transcription of this gene was confirmed using biotype-specific tcpA probes. IEM revealed that El Tor TcpA was present in the TCP bundles associated with the O17 cosmid clones. Further studies suggest that regulation of the genes encoding TcpA and cholera toxin varies between different strains of El Tor biotype.

Antibodies, Bacterial↗
PubMed1993

The role of toxin-coregulated pili in the pathogenesis of Vibrio cholerae O1 El Tor.

Studies in the infant mouse cholera model have evaluated the significance of toxin-coregulated pili (TCP) in the pathogenesis of Vibrio cholerae strains of El Tor biotype. Four El Tor strains--two which produce TCP during in vitro growth and two which do not--were mutated by the insertion of an antibiotic-resistance cartridge into the tcpA gene (encoding the pilin monomer). The resulting mutants were otherwise indistinguishable from wild-type and in particular were unaltered in their sensitivity to antibody-dependent, complement-mediated bacteriolysis. All were dramatically attenuated and showed a marked impairment in terms of in vivo persistence in mixed-infection competition experiments. Virulence was restored by provision of a functional tcp operon in trans, confirming that the pathogenic potential of El Tor strains is critically dependent upon product(s) of this operon.

Animals↗
PubMed1993

A weighted time budget approach for the assessment of cognitive and social activities.

An instrument designed to assess potentially challenging cognitive and social activities in a wide range of both psychiatric and normal study populations is described in this paper. The technique used combines traditional time budget approaches with an additional, significant component, i.e. a rating indicating the amount of challenge for each activity that is sampled. Separate ratings reflecting the subject's and the interviewer's perspective are generated. Along with a detailed description of this weighted time budget instrument, preliminary data regarding practicality, reliability and validity are reported. An analysis based on time budget interviews with 30 schizophrenic patients showed overall interrater agreement to average 84% (kappa = 0.72). In a study with a possible bearing on the concurrent validity of the instrument, relapsing schizophrenics significantly differed from stable subjects in weighted time budget indices.

Activities of Daily Living↗
PubMed1992

Three-dimensional motility cycle in leukocytes.

A 3-dimensional dynamic image analyzing system (3D-DIAS) has been developed in which a translocating cell is optically sectioned in the z-axis within a 2 sec period; the perimeter of the cell in each section is digitized into the 3D-DIAS data file, and the digitized perimeters are wrapped in order to reconstruct the cell image in three dimensions. Using 3D-DIAS, we have obtained the first dynamic 3-dimensional description of human polymorphonuclear leukocytes (PMN) translocating on a glass surface. A general behavior cycle has emerged which includes two phases. In the first, an ellipsoidal PMN with significant z-axis extends anteriorly and descends to the substratum. When the ventral surface of the anterior end contacts the substratum, there is rapid anterior expansion, which correlates with velocity peaks. In the second phase, the elongate PMN stops translocating along the substratum, the anterior end lifts off of the substratum, sometimes to heights greater than the length of the PMN at the substratum, and finally the PMN retracts into an ellipsoidal morphology still capable of random protrusions. During this second phase, which correlates with velocity troughs, turning usually occurs. The degree of turning is restricted by the continuous integrity of the posterior uropod. The period of the behavior cycle varies from roughly 0.5 to 2 min between PMNs, but is relatively constant within each individual PMN.

Cell Movement↗
PubMed1990

Intracellular vesicle movement, cAMP and myosin II in Dictyostelium.

Dictyostelium amoebae were analyzed before and after rapid addition of 10(-6) M cAMP for cellular motility, dynamic shape changes, and intracellular particle movement. Before cAMP addition, amoebae moved in a persistent anterior fashion and were elongate with F-actin localized predominantly in the anterior pseudopod. Intracellular particles moved rapidly and anteriorly. Within seconds after 10(-6) M cAMP addition, cells stopped translocating, pseudopod formation ceased, intracellular particle movement was depressed, and F-actin was lost from the pseudopod and concomitantly relocalized in the cell cortex. After 10 seconds, expansion zones reappeared but were small and no longer anteriorly localized. Vesicle movement partially rebounded but was no longer anteriorly directed. The myosin II null mutant HS2215 exhibited both depressed cellular translocation and vesicle movement. The addition of cAMP to HS2215 cells did not result in any detectable change in the random, depressed movement of particles. The results with HS2215 suggest that myosin II is essential for (1) rapid cellular translocation, (2) cellular polarity, (3) rapid particle movement, (4) anteriorly directed particle movement, and (5) the cAMP response. Electron micrographs suggest that at least half of the particles examined in this study contain in turn smaller membrane bound vesicles or multilamellar membrane bodies. The possible role of these vesicles is discussed.

Actins↗
PubMed1990

Switching at the cellular level in the white-opaque transition of Candida albicans.

The 'white-opaque transition' in Candida albicans strain WO-1 provides a unique system for analysing high-frequency switching at the cellular level because of the difference in the budding phenotypes of the white and opaque phases. Single white and opaque cells were placed on agar and monitored for the dynamics of cell division, microcolony genesis and switching to the alternative phase. It is demonstrated that at 24 degrees C, opaque cells can switch directly to white cells but white cells first generate an elongate, pseudohyphal-shaped precursor in the transition to an opaque cell. Cells in either phase can generate a daughter cell in the alternative phase, then revert immediately to the genesis of subsequent daughter cells in the original phase. By developing a mathematical model for switching at the cellular level which subtracts mother cells and switched daughter cells from the pool of switching candidates, the probability for an opaque cell to generate a white daughter cell in any single generation was calculated to be 1.0 x 10(-1) and the probability for a white cell to generate an opaque daughter cell in any single generation was calculated to be 1.7 x 10(-5) at 24 degrees C on nutrient agar. The mean number of generations before an opaque cell generated a white daughter cell was calculated to be 3.4 and the mean number before a white cell formed an opaque cell was calculated to be 15.8 at 24 degrees C on nutrient agar. Finally, high-temperature induction of the opaque to white transition was analysed at the cellular level and demonstrated to involve frequent bipolar formation of white daughter cells on the original opaque mother cell, and in some cases intermediate phenotypes.

Candida albicans↗
PubMed1990

Computer-assisted methods for assessing strain relatedness in Candida albicans by fingerprinting with the moderately repetitive sequence Ca3.

When used to probe EcoRI-digested Candida albicans DNA, the moderately repetitive sequence Ca3 generated a Southern blot hybridization pattern which included 15 to 25 bands, depending upon the strain. The pattern was stable through 400 generations in each of three independent strains but variable between most of 46 unrelated tester strains, making it a very effective probe for discrimination between strains. Computer-assisted methods (Dendron) were developed for storage of Ca3 patterns in data files, calculation of similarity (SAB) values between strains based upon band positions and intensities, and generation of histograms and dendrograms based on SAB values for all strains or any subset of strains in large epidemiological studies. In testing the effectiveness of the system, it was found that (i) multiple isolates from different body locations of the same healthy individual could represent either the same strain or different strains, (ii) isolates from oral lesions of a husband and wife represented the same strain, (iii) strains isolated from the mouths of 10 healthy individuals on the same day and in the same geographical location were as dissimilar on average as the 46 unrelated tester strains, and (iv) strains isolated from seven immunocompromised patients hospitalized over a 2.5-month period in the same hospital were highly similar, indicating nosocomial origin. The apparent effectiveness of these fingerprinting methods and the Dendron program suggests that interlaboratory procedures for fingerprinting should be standardized and all patterns should be analyzed and stored in a common and accessible data base for broad epidemiological analysis.

Blotting, Southern↗
PubMed1990

Differential regulation of right and left ventricular beta-adrenergic receptors in newborn lambs with experimental cyanotic heart disease.

To determine whether chronic hypoxemia secondary to an intracardiac right-to-left shunt alters regulation of the myocardial beta-adrenergic receptor/adenylate cyclase system, we produced chronic hypoxemia in nine newborn lambs by creating right ventricular outflow obstruction and an atrial septal defect. Oxygen saturation was reduced to 65-74% for 2 wk. Eight lambs served as normoxemic controls. beta-receptor density (Bmax) and ligand affinity (KD) were determined with the radio-ligand [125I]iodocyanopindolol and adenylate cyclase activity determined during stimulation with isoproterenol, sodium fluoride (NaF), and forskolin. During chronic hypoxemia, Bmax decreased 45% (hypoxemic, 180.6 +/- 31.5 vs. control, 330.5 +/- 60.1 fmol/mg) in the left ventricle (exposed to hypoxemia alone) but was unchanged in the right ventricle (exposed to hypoxemia and pressure overload). KD was not different from control in either ventricle. Left ventricular isoproterenol-stimulated adenylate cyclase activity was decreased by 39% (30.0 +/- 4.3% increase vs. 44.1 +/- 9.5% increase) whereas right ventricular adenylate cyclase activity was unchanged. Stimulation of adenylate cyclase with NaF or forskolin was not different from control in either ventricle. Circulating epinephrine was increased fourfold whereas circulating and myocardial norepinephrine were unchanged. These data demonstrate a down-regulation of the left ventricular beta-adrenergic receptor/adenylate cyclase system during chronic hypoxemia secondary to an intracardiac right-to-left shunt.

Adenylyl Cyclases↗
PubMed1989

A prospective study of the active management of labor in women of high parity.

High parity has been suggested as contra-indication for the use of oxytocin stimulation in labor. The aim of our study was to prospectively evaluate a protocol of oxytocin administration in 130 consecutive low-risk patients having their sixth or subsequent delivery. Induction of labor failed only in 5 cases. No adverse effect on maternal and perinatal outcome was found. We conclude that with the introduction of electronic fetal monitoring and direct recording of uterine activity, oxytocin can be safely used for low-risk grand multiparae.

Adult↗
PubMed1989

cAMP-mediated inhibition of intracellular particle movement and actin reorganization in Dictyostelium.

Before addition of cAMP, Dictyostelum amoebae rapidly translocating in buffer are elongate, exhibit expansion zones primarily at the anterior end and filamentous actin (F-actin) localization primarily in the anterior pseudopodia. Intracellular particle movement is primarily in the anterior direction, and the average rate of particle movement is roughly five times the rate of cellular translocation. Within seconds after the addition of 10(-6)M cAMP, there is a dramatic suppression of cellular translocation, an inhibition of pseudopod formation, a freeze in cellular morphology, a dramatic depression in intracellular particle movement, loss of F-actin localization in pseudopodia concomitant with relocalization of F-actin in the general cytoplasmic cortex under the plasma membrane, and a doubling of F-actin content. After 10 s, expansion zones are again visible at the cell perimeter, but they no longer are localized in the original anterior portion of the cell. There is a slight rebound in particle movement after 10 s, but particles with persistent tracks now show no directionality towards the original anterior portion of the cell, as they did before cAMP addition. Finally, in parallel with the resumption of peripheral expansion and the small rebound in particle movement, there is a decrease in total cellular F-actin to the untreated level. The pattern of microtubule organization is unaffected by the addition of cAMP.

Actins↗
PubMed1989

Controlled prospective study of oral amoxycillin/clavulanate vs ciprofloxacin in acute exacerbations of chronic bronchitis.

This investigation compared the efficacy of oral formulations of amoxycillin/clavulanate and ciprofloxacin in acute exacerbations of chronic bronchitis. Forty patients were randomized to receive either Augmentin (1,000 mg amoxycillin +250 mg clavulanate) tds or ciprofloxacin (500 mg) bd. During and before therapy sputum samples were taken for bacteriology, sputum volume measurement and histamine determination. Lung function was also monitored. From sputum, 143 bacterial isolates and 15 yeast strains were obtained before therapy. During therapy with amoxycillin/clavulanate the incidence of Gram-positive isolates decreased significantly whereas ciprofloxacin left their frequency unchanged. On the other hand, ciprofloxacin more effectively diminished the incidence of Gram-negative isolates. Yeasts were grown from the sputum of several patients before and during therapy. Their number did not increase during amoxycillin/clavulanate therapy while it increased under ciprofloxacin. The groups showed no significant differences with regard to sputum production, histamine concentration or lung function. The majority of patients (28/40) acknowledged improvement of their symptoms. There was no significant difference between the groups. On the basis of these results both amoxycillin/clavulanate and ciprofloxacin appear of similar value for treatment of patients with exacerbations of chronic bronchitis.

Aged↗
PubMed1988

"Dynamic Morphology System": a method for quantitating changes in shape, pseudopod formation, and motion in normal and mutant amoebae of Dictyostelium discoideum.

An automated, video-driven system was used to measure approximately 30 parameters of cell motion and accompanying changes in shape. This "Dynamic Morphology System" is based upon the Expertvision Motion Analysis System and is driven by a SUN computer. With the aid of this system, amoebic movement and shape changes were compared for vegetative wild-type Dictyostelium discoideum amoebae and a motility mutant, Mo-1. The measured parameters included speed, angle change, bearing, length, width, roundness, boundary flow, and curvature; and cell behavior was visualized monitoring amoebic tracks, difference pictures, and a newly developed ring expansion plot. Wild-type cells remained elongated, moved continuously and retained polarity throughout migration. In contrast, Mo-1 did not translocate, was round rather than elongated, formed bulges rather than elongated pseudopods, and exhibited no polarity. In contrast to the anterior f-action distribution in wild-type cells, f-actin in Mo-1 was distributed evenly as a shell just under the entire plasma membrane, a distribution consistent with the lack of polar cytoplasmic expansion.

Actins↗
PubMed1987

Amebae of Dictyostelium discoideum respond to an increasing temporal gradient of the chemoattractant cAMP with a reduced frequency of turning: evidence for a temporal mechanism in ameboid chemotaxis.

In an aggregation territory of Dictyostelium discoideum, outwardly moving, nondissipating waves of the chemoattractant cAMP sweep across each ameba. At the front of each wave, an ameba experiences an increasing temporal and a positive spatial gradient of cAMP. At the back of a wave, an ameba experiences a decreasing temporal and a negative spatial gradient of cAMP. Employing a perfusion chamber, we have mimicked the temporal dynamics of these waves in the absence of a spatial gradient and demonstrated that the frequency of lateral pseudopod formation and the frequency of turning are dramatically affected by the direction and dynamics of the temporal gradient. In addition, since an ameba will move in a directed fashion up a shallow, nonpulsatile gradient of cAMP, we also mimicked the increasing temporal gradient generated by an ameba moving up a shallow spatial gradient. The frequency of lateral pseudopod formation and the frequency of turning were depressed. Together, these results demonstrate that amebae can assess the direction of a temporal gradient of chemoattractant in the absence of a spatial gradient and alter both the frequency of pseudopod extension and turning, accordingly. Although these results do not rule out the involvement of a spatial mechanism in assessing a spatial gradient, they strongly suggest that the temporal dynamics of a cAMP wave or the temporal gradient generated by an ameba moving through a spatial gradient may play a major role in chemotaxis.

Cell Movement↗
PubMed1987

Frequency and orientation of pseudopod formation of Dictyostelium discoideum amebae chemotaxing in a spatial gradient: further evidence for a temporal mechanism.

Amebae of Dictyostelium discoideum normally chemotax to aggregation centers by assessing the direction of outwardly moving, nondissipating waves of the chemoattractant cAMP. However, D. discoideum amebae can also assess the direction of a relatively stable spatial gradient. We demonstrate that amebae migrating towards the "source" of a stable, spatial gradient move faster, extend fewer pseudopodia, and turn less frequently than amebae migrating away from the "source" in the same spatial gradient. In addition, amebae extend lateral pseudopods in a polarized fashion from the anterior half of the cell, and do so as frequently towards the source as away from the source. However, those formed towards the source more often produce a turn than those formed away from the source. These results suggest that there may be two decision-making systems, one localized in the pseudopods, and one along the entire cell body; they support the suggestion that Dictyostelium amebae may employ a temporal mechanism to assess the direction of a spatial gradient of chemoattractant.

Cell Movement↗
PubMed1986

Enzyme immunoassay of serum cortisol using a new transferable needle lid technique.

A simple enzyme immunoassay of serum cortisol using for the first time a transferable needle lid as solid phase has been developed. The needles coated with second antibody and dipped into the wells of a microtitre plate bind the specific antibody of a competitive enzyme immunoassay mixture. Bound enzyme activity is estimated in the wells of another microtitre plate. This technique provides further advantages on the frequently used microtitre plate version. Washes between the immunological and the enzymatic reaction take very short time and are less laborious. Due to the facility of simultaneous starting and stopping of all reactions, a better precision and sensitivity is achieved. In the present cortisol assay, horseradish peroxidase covalently coupled to cortisol-21-hemisuccinate was used as enzyme label and tetramethylbenzidine as the chromogen for measuring enzyme activity. No extraction or deproteinization steps are involved. The turn around time for 41 samples (in duplicate) is 2.5 h. The detection limit of the assay is 5 pg of cortisol per well. Results of the present method correlated well (r = 0.92) with those of a commercial radioimmunoassay using iodinated cortisol.

Humans↗
PubMed1986

Simultaneous enzyme immunoassay of cortisol and dehydroepiandrostone-sulphate from a single serum sample using a transferable solid phase system.

An enzyme immunological methodology for the direct and simultaneous estimation of serum cortisol and dehydroepiandrosterone-sulphate (DHEA-S) useful for the biochemical differential diagnosis of Cushing's syndrome has been developed. The combined estimation of both steroids is more economical in time, work and materials than two separate assays. Two solid phases, a microtitre plate and a covering transferable needle lid system were used in the present procedure. Both solid phases are first coated with anti-rabbit IgG and then each with a specific antiserum. Horseradish peroxidase was used as marker enzyme and tetramethylbenzidine as the chromogen for measuring enzyme activity. No extraction or deproteinization steps are involved. The turn around time for 41 samples (in duplicate) is 3 h. The detection limit of the assay is 5 pg/well for cortisol and 10 pg/well for DHEA-S. Results of the present method correlated well (cortisol, r = 0.95; DHEA-S, r = 0.98) with those of commercial radioimmunoassays using iodinated labels. Thus, this technique offers a convenient non-isotopic procedure in the routine clinical laboratory.

Dehydroepiandrosterone↗