Scanning Electron Microscopy of Oral Mucosa In Vivo and In Vitro: A Review

The oral mucosa is classified by function into lining, masticatory and specialized oral mucosa, with regional structural adaptation. In this review, the surface structures of the human oral mucosa have been studied in the scanning electron microscope (SEM). Regional variations in regard to keratinization, cell arrangements and microplications with related specific structures observed in SEM are described and correlated with the appearance of similar areas observed in the light microscope. Furthermore, human oral tissue and cell cultures have also been studied. These systems offer usable and complementary models for performing similar studies in vitro under controlled experimental conditions. We now show that explant cultures of human oral mucosa can propagate both normal epithelial cells and fibroblasts. The surface morphology of both cell types has been investigated in SEM

The simultaneous and nearly-collinear K0K^{0} beams for experiment NA48

A system of simultaneous and nearly-collinear beams of long- and short-lived neutral kaons has been installed and extensively studied. These beams form an integral part of the NA48 experiment at the CERN SPS, which aims to study direct CP-violation. The beam splitting is achieved by a novel application of a bent silicon crystal. The principles and design of these beams, as well as their performance are described

The simultaneous long- and short-lived neutral kaon beams for experiment NA48

Simultaneous, nearly-collinear beams of long- and short-lived neutral kaons are an essential feature of the precision CP-violation experiment NA48 *) at the SPS. The present report describes the design and performance of these beams in relation to the requirements of the experiment

Tissue response of radiation therapy assessed by electrical impedance spectroscopy (EIS) in subcutaneous tumours in rats.

The present investigation aims to evaluate the possibility of using bio-impedance spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance measurements performed with CythorLab™ equipped with a signal generator with a known high output impedance and signal measuring device able to measure the voltage applied by the generator. The control unit triggers the signal generator that generates an MLS-sequence. The same control unit process the signal that simultaneously measured by the voltage-recording device. An FFT analysis performed to obtain the magnitude of the real and imaginary parts of the impedance spectrum. The effect of various numbers of fractions of radiation therapy (RT) on the impedance measured with surface plate electrodes investigated in male rats of the Fischer-344 strain with rat glioma N32 tumours implanted subcutaneously on the flank. Tumours produced by injecting 100 000 N32 tumour cells just below the skin. Tumours were treated about four weeks after injection when a solid tumour has developed with a diameter of 1-1.5 cm. Before treating the tumours, animals anaesthetised, and the fur over the tumour shaven and carefully to ensure good electrical contact between electrodes and skin. The electrical impedance dispersion of tissue modelled with an RC-equivalent circuit from which collective impedance parameters corresponding the cell membranes, Rm Cm intra -cellular resistance, Ri, and extra-cellular resistance R0.Impedance measurements performed over a tumour before irradiation to 5 Gy and every minute after the irradiation up to 8 minutes. A slight increase of impedance, and with a time constant of 10 minutes. The growth might be due to dry skin after irradiation or a decrease of tumour vascularity during the treatment. The capacitance of the cell membrane related to the characteristic frequency fc does not change significantly before and after radiation exposure. A special parameter, the "Loss Change Index" (LCI) which defined to vary between zero if there is no change in the phase angle and one if the phase angle after exposure approach zero. LCI reach an extreme at the characteristic frequency. The LCI value recorded at the characteristic frequency fc varied with the accumulated absorbed dose and fitted to a sigmoidal dose/response relationship

Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of Pb ion operation in the LHC, with focus on the ALICE interaction region, and show that the expected heat load during nominal Pb operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.Comment: 17 pages, 20 figure

A 23 kDa membrane glycoprotein bearing NeuNAcα2-3Galβ1-3GalNAc O-linked carbohydrate chains acts as a receptor for Streptococcus sanguis OMZ 9 on human buccal epithelial cells

Streptococcus sanguis colonizes several human oral surfaces, including both hard and soft tissues. Large salivary mucin like glycoproteins bearing sialic acid residues are known to bind various S.sanguis strains. However, the molecular basis for the adhesion of S.sanguis to human buccal epithelial cells (HBEC) has not been established. The present study shows that S.sanguis OMZ 9 binds to exfoliated HBEC in a sialic acid-sensitive manner. The desialylation of such cells invariably abolhhes adhesion of S.sanguis OMZ 9 to the cell surface. A soluble glycopeptide bearing short sialylated O-linked carbohydrate chains behaves as a potent inhibitor of the attachment of S.sanguis OMZ 9 to exfoliated HBEC. The resialylation of desialylated HBEC with CMP-sialic acid and Galβ1,3GalNAc α2,3-sialyltransferase specific for O-glycans restores the receptor function for S.sanguis OMZ 9, whereas a similar cell resialylation with the Galβ1,4GlcNAc α2,6-sialyltmnsferase specific for N-glycans is without effect. Finally, ceinyl-sialic acid as a substrate yeilds exfoliated HBFC bearing flurescence as the catalyst. The latter finding demonstrates that this 23kDa cell surface glycoprotein bears NeuNAcα2-3Galβ1-3GalNAc O-linked sugar chains, a carbohydrate sequence which is recongnized by S.sanguis OMZ 9 on exfoliated HBEC. In similar experiments carried out with a buccal carcinoma cell line termed SqCC/Y1 S.sanguis OMZ 9 did not attach in great numbers to such cultured cells, and these cells were shown to not express membrane glycoprotien bearing α2,3-sialylated O-linked carbohydrate chain