Regulation of periodontal ligament cell functions by interleukin-1beta

Periodontal ligament (PDL) cells maintain the attachment of the tooth to alveolar bone. These cells reside at a site in which they are challenged frequently by bacterial products and proinflammatory cytokines, such as interleukin-1beta (IL-1beta), during infections. In our initial studies we observed that IL-1beta down-regulates the osteoblast-like characteristics of PDL cells in vitro. Therefore, we examined the functional significance of the loss of the PDL cell's osteoblast-like characteristics during inflammation. In this report we show that, during inflammation, IL-1beta can modulate the phenotypic characteristics of PDL cells to a more functionally significant lipopolysaccharide (LPS)-responsive phenotype. In a healthy periodontium PDL cells exhibit an osteoblast-like phenotype and are unresponsive to gram-negative bacterial LPS. Treatment of PDL cells with IL-1beta inhibits the expression of their osteoblast-like characteristics, as assessed by the failure to express transforming growth factor beta1 (TGF-beta1) and proteins associated with mineralization, such as alkaline phosphatase and osteocalcin. As a consequence of this IL-1beta-induced phenotypic change, PDL cells become responsive to LPS and synthesize proinflammatory cytokines. The IL-1beta-induced phenotypic changes in PDL cells were transient, as removal of IL-1beta from PDL cell cultures resulted in reacquisition of their osteoblast-like characteristics and lack of LPS responsiveness. The IL-1beta-induced phenotypic changes occurred at concentrations that are frequently observed in tissue exudates during periodontal inflammation (0.05 to 5 ng/ml). The results suggest that, during inflammation in vivo, IL-1beta may modulate PDL cell functions, allowing PDL cells to participate directly in the disease process by assuming LPS responsiveness at the expense of their normal structural properties and functions.     

Rotationplasty as a limb salvage procedure for malignant bone tumours

We report two patients with severe haemophilia A, factor VIII < 2 u dL-1, diagnosed at birth, through isolated bleeding in the adrenal gland (case 1) and through a haematoma in the liver (case 2). In these two clinical cases, the vital emergency, with haemorrhagic shock, required early diagnosis of the hereditary coagulation defect. Generally at birth, any unexplained bleeding should prompt screening for haemophilia. In the newborn period, the PTT is inadequate for many reasons and the laboratory evaluation must include factor VIII and IX levels.     

New mode scrambler for optical fibre measurements

A new design of a mode scrambler for optical fibre measurements is presented. A rotation-splice technique has been used to mix the incoming mode power distribution in the fibre. The device is tested under different launch conditions to check its efficiency to produce a definite mode power distribution. Experimental results are presented.     

Data Flow Anomaly Detection

The occurrence of a data flow anomaly is often an indication of the existence of a programming error. The detection of such anomalies can be used for detecting errors and to upgrade software quality. This paper introduces a new, efficient algorithm capable of detecting anomalous data flow patterns in a program represented by a graph. The algorithm based on static analysis scans the paths entering and leaving each node of the graph to reveal anomalous data action combinations. An algorithm implementing this type of approach was proposed by Fosdick and Osterweil [2]. Our approach presents a general framework which not only fillls a gap in the previous algorithm, but also provides time and space improvements.     

Variation of minority carrier lifetime with level of injection in p-n-junction devices

Minority-carrier lifetime as a function of level of injection has been measured for a number of Si and Ge p-n-junction diodes using reverse recovery and forward current-induced voltage decay methods. It is found that the lifetime always increases with injection level if the effect of the finite thickness of the base of the diode is taken into account while interpreting the experimental results. The decrease in the life-time values reported in the literature appears to be due to erroneous interpretation of the experimental data.     

Texture characterization of autogenous Nd:YAG laser welds in AA5182-O and AA6111-T4 aluminum alloys

This article reports a study of texture characterization in Nd:YAG laser welds of AA5182-O and AA6111-T4 alloys. Electron backscattering diffraction (EBSD) in the scanning electron microscope was used to determine the texture. The determination was made as a function of thickness through the sample. The results show that the welds can develop significant texture. In particular, the columnar grains that grow from the base metal into the weld have a strong 001 texture along the direction of growth. The work at Brown University was supported by GM through the GM Collaborative Research Lab at Brown University.     

Use of statistical methods for estimation of total number of charges in a mass spectrometry experiment

Estimation of the number of ions in a mass spectrometry experiment is needed to determine instrumentation parameters such as ionization efficiency, collision-induced dissociation efficiency, ion-transfer efficiency, ion trapping efficiency, and preamplifier detection limit. This work aims at analyzing the statistical characteristics (primarily variance) in the intensities of the isotopic distributions, which depend on the number of ions in the cell. A mathematical derivation was developed based on the maximum likelihood estimation method, which estimates the most likely number of ions in the cell using a method known as nonrandom parameter estimation. The performance of the method improves with increase in the number of observed distributions. The method works well provided the spectra show isotopic resolution and is independent of the instrument or method used to arrive at the spectra.