Human bocavirus DNA detected by quantitative real-time PCR in two children hospitalized for lower respiratory tract infection.
Explore the source record for details and available documents.
Base Sequence↗
Biomedical subjects
T Schenk
Publications and source records attributed to T Schenk.
In situ and real-time probing of quasicrystal solidification dynamics by synchrotron imaging.
Quasicrystal growth remains an unsolved problem in condensed matter. The dynamics of the process is studied by means of synchrotron live imaging all along the solidification of icosahedral AlPdMn quasicrystals. The lateral motion of ledges driving faceted growth at the solid-melt interface is conclusively shown. When the solidification rate is increased, nucleation and free growth of new faceted grains occur in the melt due to the significant interface recoil induced by slow attachment kinetics. The detailed analysis of the evolution of these grains reveals the crucial role of aluminum rejection, both in the poisoning of their growth and driving fluid flow.
Journal Article↗
Physical activity is independently related to aerobic capacity in cystic fibrosis.
It is unclear whether a relationship between physical activity (PA) and maximal oxygen uptake (V'(O2,max)) exists in cystic fibrosis (CF) and, if so, whether the relationship reflects a direct effect or is mediated by the effects of confounding variables, such as pulmonary or muscle function. The objective of the present study was to determine the relationship between PA and V'(O2,max) in CF while adjusting for possible influences of confounding factors. In total, 36 female and 35 male patients with CF from Germany and Switzerland (aged 12-40 yrs, forced expiratory volume in one second (FEV1) 25-107% predicted) were studied. A Wingate test was employed to measure muscle power. PA was monitored for 7 days and expressed in two ways: 1) average daily accelerometer count (ADAC) and 2) time spent in moderate-to-vigorous PA (MVPA). V'(O2,max) was determined during an incremental cycle exercise test to volitional fatigue. PA was positively related to V'(O2,max). In a multiple linear regression analysis, height, sex, FEV1, muscle power and ADAC (additionally explained variance 2.5%) or time spent in MVPA (additionally explained variance 3.7%) were identified as independent predictors of V'(O2,max). In conclusion, high levels of physical activity in addition to good muscular and pulmonary functions are associated with a high aerobic capacity in cystic fibrosis.
Adolescent↗
Liquid chromatography coupled on-line to flow cytometry for postcolumn homogeneous biochemical detection.
The feasibility of flow cytometry as read-out principle for homogeneous cell- or bead-based assays coupled on-line to LC is demonstrated using digoxin-coated beads (Dig-Beads) and fluorescent-labeled anti-digoxin (AD-FITC) as model system. The assay is carried out in a postcolumn continuous-flow reaction detection system where the AD-FITC and Dig-Beads are simultaneously added to the eluate of an LC separation column. Binding of AD-FITC to Dig-Beads results in a constant amount of fluorescence associated with the beads, which is detected by the flow cytometer. The presence of active compounds, such as digoxin and its analogues, in the sample will results in a decrease of the AD-FITC-Dig-Bead complex and, consequently, in the bead-associated fluorescence. Hence, the bead-associated fluorescence detected is inversely related to the digoxin concentration. A data-handling algorithm was developed in-house for adequate analysis of raw data output from the flow cytometer. Various conditions that influence the performance of this novel LC-biochemical detection (LC-BCD) system were investigated to determine the optimal settings of the bead-based biochemical interaction. The optimized flow injection bead-based assay was capable of detecting very low concentrations of digoxigenin (0.5 nmol/L), digoxin (0.1 nmol/L), and gitoxigenin (50 nmol/L). The applicability of LC coupled on-line to flow cytometry was demonstrated by the individual detection of digoxin, digoxigenin, and gitoxigenin in a single LC analysis. The successful coupling of LC on-line to flow cytometry principally enables the use of a wide range of new homogeneous assay formats in LC-BCD, such as membrane-bound receptor assays, cell-binding assays, and functional cell-based assays. Next to the ability to use insoluble targets, and also multiplexing assays, i.e., performing a number of assays simultaneously, using color- or size-coded beads becomes at hand in LC-BCD.
Journal Article↗
A generic assay for phosphate-consuming or -releasing enzymes coupled on-line to liquid chromatography for lead finding in natural products.
A generic continuous-flow assay for phosphate-consuming or -releasing enzymes coupled on-line to liquid chromatography (LC) has been developed. Operating the LC-biochemical assay in combination with mass spectrometry allows the fast detection and identification of inhibitors of these enzymes in complex mixtures. The assay is based on the detection of phosphate, released by the on-line continuous-flow enzymatic reaction, using a fluorescent probe. The probe consists of fluorophore-labeled phosphate-binding protein, which shows a strong fluorescence enhancement upon binding to inorganic phosphate. To detect very small changes of the phosphate concentration in a postcolumn enzymatic reaction medium, the enzymatic removal of phosphate impurities from solvents, reagents, and samples was optimized for application in continuous flow. The potential of the phosphate probe is demonstrated by monitoring the enzymatic activity, i.e., the phosphate release, from alkaline phosphatase. The selectivity of the phosphate readout, necessary to distinguish between phosphate containing substrate or product and free inorganic phosphate released after enzymatic conversion, is shown. The applicability of LC coupled to the enzymatic assay using the phosphate readout was demonstrated by detection of tetramisole in a plant extract as inhibitor of alkaline phosphatase. Parallel mass spectrometry allowed the simultaneous confirmation of the identity of the inhibitor.
Alkaline Phosphatase↗
Screening of natural products extracts for the presence of phosphodiesterase inhibitors using liquid chromatography coupled online to parallel biochemical detection and chemical characterization.
The ability to rapidly identify active compounds in a complex mixture (e.g., natural products extract) is still one of the major problems in natural products screening programs. An elegant way to overcome this problem is to separate the complex mixture by gradient liquid chromatography followed by online biochemical detection parallel with chemical characterization, referred to as high-resolution screening (HRS). To find and identify phosphodiesterase (PDE) inhibitors in natural products extracts using the HRS technology, the authors developed a continuous-flow PDE enzymatic assay. The suitability of the continuous-flow PDE enzymatic assay for natural products screening was demonstrated. After optimization of the continuous-flow PDE assay, the limit of detection for 3-isobutyl-1-methyl-xanthine (IBMX) was 1 muM, with a dynamic range from 1 to 100 muM IBMX. The applicability of the HRS technology for the detection of PDE inhibitors in natural products extracts was demonstrated by the analysis of a plant extract spiked with 2 naturally occurring PDE inhibitors. The plant extract was analyzed with 2 assay lines in parallel, enabling background fluorescence correction of the sample. The simultaneous quantification of the active compounds using evaporative light-scattering detection allowed the estimation of the IC(50) value of the active compounds directly in the crude extract.
1-Methyl-3-isobutylxanthine↗
Icosahedral short-range order in deeply undercooled metallic melts.
Experimental evidence of icosahedral short-range order in stable and deeply undercooled melts of pure metallic elements is obtained using the combination of electromagnetic levitation with neutron scattering. This icosahedral short-range order is shown to occur in the bulk metallic melt independently of the system investigated. It strongly increases with the degree of undercooling.
Journal Article↗
Is writer's cramp caused by a deficit of sensorimotor integration?
Writer's cramp is a highly specific movement disorder in which handwriting is impaired while most other manual skills are often unaffected. On the basis of abnormal findings in experiments measuring the control of grip forces, it has been suggested that writer's cramp is caused by a deficit of sensorimotor integration. The aim of our study was to determine whether there is a functional link between sensory deficits, abnormalities in the control of grip force, and handwriting disorders. We compared the grip force and handwriting performance of writer's cramp patients with that of control subjects and with that of a stroke patient suffering a purely somatosensory deficit of his dominant hand (patient S1). We found that: (1) writer's cramp patients and patient S1 had elevated grip-force levels; (2) training reduced the grip force to near-normal levels in all writer's cramp patients but not in S1; (3) effortful writing performance also induced increased grip-force levels in healthy subjects; and (4) patient S1 had normal handwriting movements. These findings suggest that the elevated pretraining gripforce levels of writer's cramp patients might be a consequence of their effortful writing style and do not reflect a deficit of sensorimotor integration. Moreover, the good handwriting performance of patient S1 shows that a severe somatosensory deficit is not a sufficient condition for a handwriting disorder. These findings disagree with the sensorimotor explanation of writer's cramp.
Adult↗
Potential of on-line micro-LC immunochemical detection in the bioanalysis of cytokines.
An on-line liquid chromatography-immunochemical detection (LC-ICD) system for the quantification of cytokines in cell extracts has been developed using a post-column continuous-flow reaction detection system using fluorescence labelled antibodies. Cytokines eluting from the micro-HPLC column react with antibodies to form fluorescent complexes. In a second step the excess of free antibody is trapped on a cytokine bound support prior to fluorescence detection. The concentration detection limit of the flow injection-ICD system was 50 pM (20 microl injection volume) for interleukin 4 (IL-4). An absolute detection limit of 1 fmol was obtained for IL-4. Similar to ICD systems for small non-protein analytes developed earlier, reaction times were in the order of 1 minute. The immobilised cytokine affinity columns can easily be regenerated and used for months. The present ICD system for interleukins 4, 6, 8 and 10 was coupled to ion exchange-, size exclusion- and reversed phase chromatography. Important parameters (reaction times, reaction conditions) were investigated to get a better understanding of post-column ICD systems for macromolecules.
Chromatography, Gel↗
Expression of bcr-abl mRNA in individual chronic myelogenous leukaemia cells as determined by in situ amplification.
We present the results of a novel method developed for evaluation of in situ amplification, a molecular genetic method at the cellular level. Reverse transcription polymerase chain reaction (RT-PCR) was used to study bcr-abl transcript levels in individual cells from patients with chronic myelogenous leukaemia (CML). After hybridizing a fluorochrome-labelled probe to the cell-bound RT-PCR product, bcr-abl mRNA-positive cells were determined using image analysis. A dilution series of bcr-abl-positive BV173 into normal cells showed a good correlation between expected and actual values. In 25 CML samples, the percentage of in situ PCR-positive cells showed an excellent correlation with cytogenetic results (r = 0.94, P < 0.0001), interphase fluorescence in situ hybridization (FISH) (r = 0.95, P = 0.001) and hypermetaphase FISH (r = 0.81, P < 0.001). The fluorescence intensity was higher in residual CML cells after interferon (IFN) treatment than in newly diagnosed patients (P = 0.004), and was highest in late-stage CML resistant to IFN therapy and lowest in CML blast crisis (P = 0.001). Mean fluorescence values correlated with bcr-abl protein levels, as determined by Western blot analysis (r = 0.62). Laser scanning cytometry allowing automated analysis of large numbers of cells confirmed the results. Thus, fluorescence in situ PCR provides a novel and quantitative approach for monitoring tumour load and bcr-abl transcript levels in CML.
Analysis of Variance↗
Arthroscopic capsular release for the treatment of refractory postoperative or post-fracture shoulder stiffness.
BACKGROUND: Arthroscopic capsular release is used to treat idiopathic adhesive capsulitis (frozen shoulder) that is refractory to nonoperative treatment or manipulation under anesthesia. The role of arthroscopic capsular release in the treatment of frozen shoulder after shoulder surgery or fracture is less clearly understood. The purposes of this study were to define the outcome of arthroscopic capsular release in the management of frozen shoulder after surgery or fracture and to compare these results with those of arthroscopic capsular release in the treatment of idiopathic frozen shoulder. METHODS: We evaluated the results of arthroscopic capsular release in three different groups of patients with shoulder contracture refractory to nonoperative management and manipulation under anesthesia. The three groups consisted of patients who had an idiopathic frozen shoulder, shoulder stiffness after surgery, or shoulder stiffness after fracture. We evaluated pain, function, patient satisfaction, and range of motion in all three groups before and after the study treatment. RESULTS: At a mean of twenty months (range, twelve to forty-six months) after the operation, fifty patients were available for assessment of function and range of motion of the involved shoulder. At the time of follow-up, each group had a significant improvement in the scores for pain, patient satisfaction, and functional activity as well as in the overall outcome score (p < 0.01). Comparison of the scores among the different groups revealed that all had a similar degree of improvement in range of motion of the involved shoulder, but patients with postoperative frozen shoulder had significantly (p < 0.05) lower scores for pain (p < 0.03), patient satisfaction (p < 0.004), and functional activity (p < 0.002) than did those with idiopathic or post-fracture frozen shoulder. CONCLUSIONS: Arthroscopic capsular release was as effective for improving range of motion in patients with postoperative contracture of the shoulder as it was in patients with idiopathic and post-fracture contracture. However, there was less improvement in the subjective scores for pain, function, and patient satisfaction in the postoperative group.
Analysis of Variance↗
A system for the study of visuomotor coordination during reaching for moving targets.
Prehensile behavior is a popular task in current research on human motor control. Most studies on reaching used stationary target objects and, therefore, most models do not address the challenges the motor system must respond to when reaching for moving objects. The machines used in earlier studies to produce object motion offered a limited range of trajectories and restricted control over various movement parameters. We have developed a device that allows a great variety of object trajectories along a flat-table surface and gives the experimenter full control over all movement parameters. A linear positioning system is used to move a sled beneath the table surface. Magnetic coupling transfers the sled's movement to the target object on the tabletop. This arrangement allows fast movements of the object (up to 5 m/s) and at the same time protects subjects from any harm due to the moving parts. The system is connected to LC shutter glasses, a 3-D movement registration device, and a switch that detects the onset of hand motion. This allows the selective withdrawal of vision during the reaching task or the introduction of changes in the object motion depending on the subject's reactions.
Electronic Data Processing↗
Cell-surface exposure of phosphatidylserine correlates with the stage of fludarabine-induced apoptosis in chronic lymphocytic leukemia and expression of apoptosis-regulating genes.
BACKGROUND: Programmed cell death (PCD) is characterized by a sequence of tightly regulated events that result in the activation of caspases and in internucleosomal DNA cleavage. Late apoptotic events such as DNA-strand breaks can be assayed by in situ end labeling (ISEL) and DNA measurement (sub G1) using flow cytometry. Phosphatidylserine (PS) redistribution from the inner plasma membrane leaflet to the outer leaflet, an early event in PCD, can be detected by annexin V (AxV) binding to PS. AxV-fluorescein isothiocyanate (FITC) fluorescence intensity is variable and characterizes different cell populations, denoted here as AxV-negative (AxV(neg)), AxV-low-positive (AxV(lo)), and AxV-high-positive (AxV(hi)). METHODS: We investigate the correlation of three methods (ISEL, sub G1 DNA content, and AxV assay) for detecting apoptosis with focus on differences between populations with different levels of PS. We also examined the expression of PCD-regulating Bcl-2 family members in these cell populations by reverse transcription-polymerase chain reaction (RT-PCR). Chronic lymphocytic leukemia (CLL) cells exposed to fludarabine (FAMP) were used as an in vitro model. Cells with different PS/AxV levels were separated using fluorescence-activated cell sorting (FACS). RESULTS: Only purified AxV(hi) cells had high positivity in the ISEL and sub G1 assays (94 +/- 0.6%, 88.6 +/- 6.6%, and 98.6 +/- 0.6%, respectively), indicating that late apoptotic cells are detected equally by all three methods. In the AxV(lo) population, ISEL was positive in 21% +/- 13% and DNA sub G1 in 20% +/- 6.6% of cells, suggesting that AxV identifies early apoptotic cells better than the other assays. Anti-apoptotic Bcl-2 and Bcl-X(L) were upregulated by FAMP when cells entered apoptosis (AxV(lo)), as was pro-apo- ptotic Bcl-X(S), which was undetectable in nonapoptotic AxV(neg) cells. Pro-apoptotic Bax was only expressed in AxV(neg) and AxV(lo) cells. Late apoptotic AxV(hi) cells did not express Bcl-X(S) or Bax. RESULTS: (1) AxV staining is more sensitive than sub G1 or ISEL in detecting early apoptotic cells; (2) only late apoptotic cells are equally detected by all assays; (3) AxV is a valuable tool in the detection and isolation of apoptotic cells at different stages of PCD; and (4) pro-apoptotic Bcl-X(S) and Bax are expressed at early, not late, stages of apoptosis.
Annexin A5↗
Dose-dependent effect of angiotensin II on human erythropoietin production.
Current evidence suggests that angiotensin II may be involved in the regulation of renal erythropoietin (EPO) production. The present study assessed the role of angiotensin II (A II) in different doses in the control of EPO production in humans. In a parallel, randomized, placebo-controlled open design, 60 healthy male volunteers received a 6-h intravenous infusion of: placebo (placebo, electrolyte solution), a pressor dose of A II (1-3 microg/min; A II press), a combination of a pressor dose of A II and the selective AT1-receptor blocker losartan, 50 mg (A II press + L), a subpressor dose of A II (0.0375-0.15 microg/min; A II subpress) and a combination of a subpressor dose of A II and losartan (A II subpress + L). A II press treatment resulted in a significant increase of the maximum EPO concentration (CmaxEPO, 41% higher versus placebo) and the amount of EPO produced in 24 h (AUCEPO(0-24 h), 61% larger versus placebo), A II subpress treatment increased CmaxEPO (35% higher versus placebo) and AUC(EPO)(0-24 h) (34% larger versus placebo). A II press + L and A II subpress + L treatments did not significantly increase CmaxEPO and AUCEPO(0-24 h) compared to placebo. A II affects EPO production in a dose-dependent manner. The signal seems to be mediated via AT1-receptors. A II appears to be one modulator EPO production in humans.
Adolescent↗
Kinematic analysis of laryngeal movements in patients with neurogenic dysphagia before and after swallowing rehabilitation.
To examine whether kinematic analysis of laryngeal movements (which are closely linked to pharyngeal swallowing) can differentiate between normal and disturbed swallowing, we used a three-dimensional ultrasound movement recording system to measure the movements of the larynx during swallowing in 32 patients with neurogenic dysphagia caused by central nervous system lesions and in 32 age- and sex-matched healthy individuals. At the beginning of an inpatient rehabilitation swallowing program, laryngeal movements in 24 patients were highly disturbed in terms of velocity curve irregularities. After rehabilitation, the majority of patients with hitherto irregular velocity profiles exhibited laryngeal kinematics that were indistinguishable from those of 32 healthy subjects. Kinematic analysis of laryngeal movements, therefore, is suitable for monitoring motor recovery of swallowing disturbances in patients with neurogenic dysphagia while undergoing swallowing rehabilitation.
Adult↗
Can a motion-blind patient reach for moving objects?
It has been claimed that the visual brain is organized in two separate processing streams for spatial vision: one for perception and one for action. To determine whether motion vision is also divided into vision for action and for perception we examined the interceptive behaviour of the motion-blind patient LM. The task for LM and three age-matched control subjects was to reach-and-grasp for an object that moved away. Three experiments were conducted to examine the effects on perfomance of target speed (Expt 1), observation time (Expt 2) and visual feedback (Expt 3). As LM is only able to reach for objects which move at 0.5 m/s or less, her performance is inferior to that of controls who can reach for objects moving at 1.0 m/s, but it is better than would be expected from her performance in psychophysical experiments on her motion vision. Kinematic analysis of LM's reaching movements showed that she adapted the speed of her moving hand to the speed of the target but only when full vision was available. In contrast to normal subjects, LM required long observation times and vision of her moving hand to produce successful reaching responses. Thus, the impairment of both perception and action in LM suggests that the motion area MT/V5 is located at an early stage of the extrastriate hierarchy and provides input to both the perception and the action processing streams.
Aged↗
Closed- and open-loop handwriting performance in patients with multiple sclerosis.
Normal subjects use an open-loop motor control strategy in handwriting, but they are able to switch to closed-loop motor control when the demands on accuracy increase. These closed-loop handwriting movements of normal subjects resemble the inefficient movements found in writing-impaired patients. The hypothesis that such movement deficits may in fact reflect the use of a closed-loop strategy was tested in a group of writing-impaired patients with multiple sclerosis (MS). The handwriting movements of 10 MS patients and 20 control subjects were examined with a digitizing tablet. Three conditions were used: a standard writing task (expt 1), a closed-loop condition (expt 2), and an open-loop condition (expt 3). Individual stroke movements were analysed. Stroke duration and segmentation were increased for MS patients in the standard writing task. The same was found for control subjects when they wrote under closed-loop conditions. However, under open-loop conditions, the handwriting movements of the MS patients were as fast and fluent as that of control subjects. The results support the hypothesis that the movement characteristics of the writing-impaired MS patients reflect an inadequate use of a closed-loop motor control strategy.
Adult↗
Effective depletion of alloreactive lymphocytes from peripheral blood mononuclear cell preparations.
BACKGROUND: T cells present in an allogeneic bone marrow transplant may produce graft-versus-host disease but also contribute to immune reconstitution and enhance engraftment. Our aim was to separate alloreactive from nonalloreactive T lymphocytes, by performing a mixed lymphocyte culture (MLC) stimulation of donor cells, followed by selective depletion of activated cells expressing the high-affinity interleukin 2 receptor. We then characterized the resulting depleted cell fraction. METHODS: Donor peripheral blood mononuclear cells were cocultured with irradiated peripheral blood mononuclear cells from HLA-nonidentical recipient stimulators in an MLC. After 3 days, CD25+ lymphocytes (alloreactive cells expressing the alpha chain of the interleukin 2 receptor) were removed by immunomagnetic separation. The depleted donor fraction and untreated cells were then rechallenged in a secondary MLC with the original irradiated stimulator cells or a third party to assess relative alloreactivity. RESULTS: Inhibition of the secondary MLC and of host-specific cytotoxic activities was observed as well as a disappearance of interleukin 2 receptor-positive cells. Alloreactivity against unrelated third-party cells was preserved. Limiting dilution analysis of residual alloantigen-reactive T lymphocytes demonstrated a 1.3 log reduction of antihost reactivity. The depletion largely removed host-specific alloreactive CD4+ cells. CONCLUSIONS: This method reduces alloreactivity while retaining reactivity against third-party targets. This approach may allow therapeutic infusion of T cells after HLA-nonidentical allografts with a reduced capacity to produce graft-versus-host disease.
Blood Component Removal↗