Jan Cornelis

Validity and reliability of the Kinect within functional assessment activities: comparison with standard stereophotogrammetry.

The recent availability of the Kinect™ sensor, a cost-effective markerless motion capture system (MLS), offers interesting possibilities in clinical functional analysis and rehabilitation. However, neither validity nor reproducibility of this device is known yet. These two parameters were evaluated in this study. Forty-eight volunteers performed shoulder abduction, elbow flexion, hip abduction and knee flexion motions; the same protocol was repeated one week later to evaluate reproducibility. Movements were simultaneously recorded by the Kinect (with Microsoft Kinect SDK v.1.5) MLS and a traditional marker-based stereophotogrammetry system (MBS). Considering the MBS as reference, discrepancies between MLS and MBS were evaluated by comparing the range of motion (ROM) between both systems. MLS reproducibility was found to be statistically similar to MBS results for the four exercises. Measured ROMs however were found different between the systems.

UV-reactivation, virus production and mutagenesis of SV40 in UV-irradiated monkey kidney cells

The survival of UV-irradiated simian virus 40 (SV40) is higher in VU-irradiated than in non-irradiated monolayers of BSC-1 monkey cells. A similar reactivation is found when cells are infected with SV40-DNA, suggesting that reactivation acts on viral DNA. The enhanced reactivation of VU-irradiated SV40 and SV40-DNA is optimal when infection is delayed for 2--3 days after irradiation of the cells. UV-pretreated cells infected with SV40-DNA produce more virus than infected control cells; the time curve of this process is similar to that found for enhanced virus reactivation and suggests that facilitated virus production in UV-irradiated cells and enhanced virus reactivation might be manifestations of the same process. If the non-irradiated SV40 thermosensitive mutant BC245 is propagated in UV-irradiated BSC-1 cells the rate of back mutation to phenotypically wild-type is increased compared with that of the control. This suggests that an inducible error-prone system is functional in these cells. When the UV-irradiated tsBC245 is propagated in non-irradiated cells the reversion frequency is greatly enhanced, which suggest that either the introduction of UV-irradiated SV40-DNA is sufficient to induce an error-generating system, or that a constitutive error-prone mechanism is operative on this DNA.

A SENSITIVE METHOD FOR MEASURING PYRIMIDINE DIMERS IN SITU

Abstract. –An immunocytological method for detecting pyrimidine dimers in situ has been developed. The technique is based on the fixation in cell nuclei of radiolabelled antibodies directed against ultraviolet irradiated DNA. The relative amount of bound antibodies was estimated by radioautography. Pyrimidine dimers induced by a dose as low as 2 J m‐2 can easily be detected. With this technique, the dose response of DNA photoproducts and their elimination by excision and photoreactivation were followed in eukaryotic cell cultures.

Immunocytochemical localization of chromatin regions UV-microirradiated in S phase or anaphase : Evidence for a territorial organization of chromosomes during cell cycle of cultured Chinese hamster cells

Chinese hamster cells (M3-1 line) in S phase were laser-UV-microirradiated (lambda, 257 nm) at a small site of the nucleus. Cells were fixed either immediately thereafter or in subsequent stages of the cell cycle, including prophase and metaphase. The microirradiated chromatin was visualized by indirect immunofluorescence microscopy using antibodies specific for UV-irradiated DNA. During the whole post-incubation period (4-15 h) immunofluorescent labelling was restricted to a small part of the nucleus (means, 4.5% of the total nuclear area). In mitotic cells segments of a few chromosomes only were labelled. Following microirradiation of chromosome segments in anaphase, immunofluorescent labelling was observed over a small part of the resulting interphase nucleus. A territorial organization of interphase chromosomes, i.e. interphase chromosomes occupying distinct domains, has previously been demonstrated by our group for the nucleus of Chinese hamster cells in G1. Our present findings provide evidence that this organization pattern is maintained during the entire cell cycle.

Determination of the precision and accuracy of morphological measurements using the Kinect™ sensor: comparison with standard stereophotogrammetry

The recent availability of the Kinect™ sensor, a low-cost Markerless Motion Capture (MMC) system, could give new and interesting insights into ergonomics (e.g. the creation of a morphological database). Extensive validation of this system is still missing. The aim of the study was to determine if the Kinect™ sensor can be used as an easy, cheap and fast tool to conduct morphology estimation. A total of 48 subjects were analysed using MMC. Results were compared with measurements obtained from a high-resolution stereophotogrammetric system, a marker-based system (MBS). Differences between MMC and MBS were found; however, these differences were systematically correlated and enabled regression equations to be obtained to correct MMC results. After correction, final results were in agreement with MBS data (p = 0.99). Results show that measurements were reproducible and precise after applying regression equations. Kinect™ sensors-based systems therefore seem to be suitable for use as fast and reliable tools to estimate morphology. Practitioner Summary: The Kinect™ sensor could eventually be used for fast morphology estimation as a body scanner. This paper presents an extensive validation of this device for anthropometric measurements in comparison to manual measurements and stereophotogrammetric devices. The accuracy is dependent on the segment studied but the reproducibility is excellent.

Transformation of established murine fibroblasts with an activated cellular Harvey-ras oncogene or the polyoma virus middle T gene increases cell permissiveness to parvovirus minute-virus-of-mice.

Transformation of permanent rodent fibroblast cells by the polyoma virus middle T gene or the activated human Harvey-ras oncogene results in increased cellular permissiveness to the autonomous parvovirus minute-virus-of-mice. Parvoviral DNA amplification is restricted in the untransformed parental cell lines. Analysis of various parameters of the parvoviral life cycle shows that this block is partially overcome in the transformed lines.

The influence of inhibitors on dimer removal and repair of single-strand breaks in normal and bromodeoxyuridine substituted DNA of HeLa cells

The elimination of cyclobutane pyrimidine dimers from the nuclear DNA of ultraviolet irradiated HeLa cells has been examined by means of chromatography and immunoautoradiography. The extent and duration of the process was similar when dimers were assayed by both methods, proving that the anti-sera recognized pyrimidine dimers. The rate of dimer excision did not differ through the cell cycle with the exception of mitosis during which no dimers were removed. Dimer excision is a relatively fast process which is terminated within a few hours, but it leaves many dimers in the DNA. Excision is depressed by inhibitors of semiconservative DNA synthesis that affect the DNA precursor pool or DNA polymerases. Cells whose DNA is partly substituted with bromodeoxyuridine instead of thymidine, repair single-strand breaks and remove dimers at the same rate but to different extents. On the other hand, inhibitors limit repair of breaks and removal of dimers to the same degree suggesting that the repair of the two types of lesion is coordinated.

The effect of cell irradiation on mutation in ultraviolet-irradiated and intact simian virus 40

The induction of phenotypic wild-type revertants in the progeny of an unirradiated or UV-irradiated temperature-sensitive late mutant of simian virus 40 was studied after low multiplicity passages in normal or UV-irradiated confluent monkey kidney cells. The production of wild-type revertants in the progeny of undamaged tsBC245 was followed by infecting the cells at distinct times after irradiation of the cells. Mutation frequencies reached a maximum when infection was delayed for 3--4 days after irradiation of the host cells, and declined gradually thereafter. Virus grown in unirradiated cells did not show such an alteration in mutation frequency. The temporarily higher mutation frequency of virus in UV-pretreated cells is due to a transient mutator activity operating in these cells rather than to an increased number of replications performed in UV-irradiated cells. A similar time course was found for the reactivation of UV-damaged SV40. This might suggest that reactivation and mutagenesis are manifestations of the same process. The yield of mutants due to irradiation of the virus alone was enhanced when infection was delayed for some days after the cells reached confluency; UV pretreatment of the host cells did not enhance the level of mutation obtained by UV irradiation of the virus.

Wavelet-based scalable L-infinity-oriented compression

Among the different classes of coding techniques proposed in literature, predictive schemes have proven their outstanding performance in near-lossless compression. However, these schemes are incapable of providing embedded Linfin-oriented compression, or, at most, provide a very limited number of potential Linfin bit-stream truncation points. We propose a new multidimensional wavelet-based Linfin-constrained scalable coding framework that generates a fully embedded Linfin-oriented bit stream and that retains the coding performance and all the scalability options of state-of-the-art L2-oriented wavelet codecs. Moreover, our codec instantiation of the proposed framework clearly outperforms JPEG2000 in Linfin coding sense

UNSCHEDULED DNA SYNTHESIS: A QUANTITATIVE INDICATOR OF RESIDUAL IMMUNODETECTABLE PYRIMIDINE DIMERS IN HUMAN FIBROBLASTS AFTER ULTRAVIOLET‐B IRRADIATION

Abstract— We have addressed the question whether the level of UV‐B induced DNA damage can be accurately assessed by the measurement of the rate of unscheduled DNA synthesis (UDS). Cultured human fibroblasts were irradiated with UV radiation at 290, 313 or 365 nm. The LD50 was 85 J/m2 at 290 nm, 4500 J/m2 at 313 nm, and 70 kJ/m2 at 365 nm. The analysis of UDS measurements indicate complete arrest of repair processes within 24 h after irradiation, irrespective of the dose (in the range 10–60 J/m2 at 290 nm, and 250–1000 J/m2 at 313 nm). Irradiation at 365 nm failed to yield detectable evidence of UDS. Incubation of irradiated cells with an antiserum directed against both 6–4 type and cyclobutane‐type pyrimidine dimers shows a clear parallelism between the disappearance of the antibody‐binding determinants and the variation of the rate of UDS vs time after the end of the irradiation. Thus it is concluded that in UV‐B irradiated normal cultured human fibroblasts, the lack of UDS reflects the absence of immunodetectable pyrimidine dimers.