238 research outputs found
Exploring the capability of wireless near infrared spectroscopy as a portable seizure detection device for epilepsy patients
AbstractPurposeNear infrared spectroscopy (NIRS) has proved useful in measuring significant hemodynamic changes in the brain during epileptic seizures. The advance of NIRS-technology into wireless and portable devices raises the possibility of using the NIRS-technology for portable seizure detection.MethodsThis study used NIRS to measure changes in oxygenated (HbO), deoxygenated (HbR), and total hemoglobin (HbT) at left and right side of the frontal lobe in 33 patients with epilepsy undergoing long-term video-EEG monitoring. Fifteen patients had 34 focal seizures (20 temporal-, 11 frontal-, 2 parietal-lobe, one unspecific) recorded and analyzed with NIRS. Twelve parameters consisting of maximum increase and decrease changes of HbO, HbR and HbT during seizures (1min before- to 3min after seizure-onset) for left and right side, were compared with the patients’ own non-seizure periods (a 2-h period and a 30-min exercise-period). In both non-seizure periods a 4min moving windows with maximum overlapping were applied to find non-seizure maxima of the 12 parameters. Detection was defined as positive when seizure maximum change exceeded non-seizure maximum change.ResultsWhen analyzing the 12 parameters separately the positive seizure detection was in the range of 6–24%. The increase in hemodynamics was in general better at detecting seizures (15–24%) than the decrease in hemodynamics (6–18%) (P=0.02).ConclusionNIRS did not seem to be a suitable technology for generic seizure detection given the device, settings, and methods used in this study. There are still several challenges to overcome before the NIRS-technology can be used as a home-monitoring seizure detection device
Indirect measurement of the magnetocaloric effect using a novel differential scanning calorimeter with magnetic field
Curli
are bacterial appendages involved in the adhesion of cells
to surfaces; their synthesis is regulated by many genes such as <i>csgD</i> and <i>ompR</i>. The expression of the two
curli subunits (CsgA and CsgB) in <i>Escherichia coli</i> (<i>E. coli</i>) is regulated by CsgD; at the same time, <i>csgD</i> transcription is under the control of OmpR. Therefore,
both genes are involved in the control of curli production. In this
work, we elucidated the role of these genes in the nanomechanical
and adhesive properties of <i>E. coli</i> MG1655 (a laboratory
strain not expressing significant amount of curli) and its curli-producing
mutants overexpressing OmpR and CsgD, employing atomic force microscopy
(AFM). Nanomechanical analysis revealed that the expression of these
genes gave origin to cells with a lower Young’s modulus (<i>E</i>) and turgidity (<i>P</i><sub>0</sub>), whereas
the adhesion forces were unaffected when genes involved in curli formation
were expressed. AFM was also employed to study the primary structure
of the curli expressed through the freely jointed chain (FJC) model
for polymers. CsgD increased the number of curli on the surface more
than OmpR did, and the overexpression of both genes did not result
in a greater number of curli. Neither of the genes had an impact on
the structure (total length of the polymer and number and length of
Kuhn segments) of the curli. Our results further suggest that, despite
the widely assumed role of curli in cell adhesion, cell adhesion force
is also dictated by surface properties because no relation between
the number of curli expressed on the surface and cell adhesion was
found
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