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Biomedical subjects

Oliver Brand

Publications and source records attributed to Oliver Brand.

6 recordsLinked to original sources
PubMed2005

HLA , CTLA-4 and PTPN22 : the shared genetic master-key to autoimmunity?

Several genetic loci appear to be involved in susceptibility to autoimmune disease. Some loci are disease specific, whereas others appear to exert a general effect on the autoimmune disease process. Despite a large number of studies of many different diseases, consistent associations with multiple autoimmune disorders have been restricted to three gene regions: the human leukocyte antigen (HLA) class II region on chromosome 6p21, the gene encoding cytotoxic T lymphocyte-associated 4 (CTLA-4) on chromosome 2q33, and the PTPN22 gene encoding lymphoid tyrosine phosphatase (LYP) on chromosome 1p13. Each of these loci is likely to encode molecules that are crucial in the immune cascade and are actively involved in T-cell activation. Moreover, gene polymorphisms that affect function might contribute to the triggering of autoimmune disease by as-yet-unknown mechanisms. This review summarises recent developments and current understanding of the way in which molecules encoded by these susceptibility loci contribute to T-cell activation, and hypothesises how aberrant function of these molecules might trigger autoimmunity.

Antigens, CD↗
PubMed2005

Association of the TSHR gene with Graves' disease: the first disease specific locus.

The development of autoimmune thyroid disease (AITD) is associated with autoantibodies directed against the thyroid stimulating hormone receptor (TSHR). Previous studies have failed to demonstrate a consistent association between the TSHR and AITD, or any of its sub-phenotypes. In the present study, we analysed the linkage disequilibrium (LD) structure encompassing the TSHR, to identify LD 'blocks' and SNPs, which capture the majority of intra-block haplotype diversity. The haplotype tagging SNPs, plus all common SNPs reported in previous studies were genotyped in 1,059 AITD Caucasian cases and 971 Caucasian controls. A haplotype, across two LD blocks, showed association (P<1 x 10(-6), OR 1.7) with Graves' disease (GD) but not autoimmune hypothyroidism (AIH). We replicated these findings by genotyping the most associated GD SNP, rs2268458, in a separate UK Caucasian cohort of 1,366 AITD cases and 1,061 controls (GD, P=2 x 10(-6), OR 1.3; AIH, P=NS). These results in two independent Caucasian data sets suggest that the TSHR is the first replicated GD-specific locus meriting further fine mapping and functional analysis to identify the aetiological variants.

Case-Control Studies↗
PubMed2004

Single-chip mechatronic microsystem for surface imaging and force response studies.

We report on a stand-alone single-chip (7 x 10 mm) atomic force microscopy unit including a fully integrated array of cantilevers, each of which has an individual actuation, detection, and control unit so that standard atomic force microscopy operations can be performed by means of the chip only without any external controller. The system offers drastically reduced overall size and costs as well as increased scanning speed and can be fabricated with standard complementary metal oxide semiconductor technology with some subsequent micromachining steps to form the cantilevers. Full integration of microelectronic and micromechanical components on the same chip allows for the controlling and monitoring of all system functions. The on-chip circuitry, which includes analog signal amplification and filtering stages with offset compensation, analog-to-digital converters, a powerful digital signal processor, and an on-chip digital interface for data transmission, notably improves the overall system performance. The microsystem characterization evidenced a vertical resolution of < 1 nm and a force resolution of < 1 nN as shown in the measurement results. The monolithic system represents a paradigm of a mechatronic microsystem that allows for precise and fully controlled mechanical manipulation in the nanoworld.

Journal Article↗
PubMed2002

Complementary metal oxide semiconductor cantilever arrays on a single chip: mass-sensitive detection of volatile organic compounds.

The sensing behavior of polymer-coated resonant cantilevers for mass-sensitive detection of volatile organic compounds was investigated. Industrial complementary metal oxide semiconductor (CMOS) technology combined with subsequent CMOS-compatible micromachining was used to fabricate a single-chip system comprising the transducers and all necessary driving and signal-conditioning circuitry. An analytical model was developed to describe the mass-sensing mechanism of polymer-coated resonant cantilevers. The model was validated by measurements of various gaseous analytes. As an exemplary application, the quantitative analysis of a binary mixture using an array of four cantilevers is described. Experimental results are given for the concentration prediction of a mixture of n-octane and toluene. Finally, it was established that the limit of detection achieved with cantilever sensors is comparable to that of other acoustic wave-based gas sensors.

Journal Article↗
PubMed2002

A complementary-metal-oxide-semiconductor-field-effect-transistor-compatible atomic force microscopy tip fabrication process and integrated atomic force microscopy cantilevers fabricated with this process.

A complementary-metal-oxide-semiconductor-field-effect-transistor-compatible process for the fabrication of atomic force microscopy cantilevers with integrated tips has been developed. For the first time, the tips are fabricated after the completion of the regular complementary metal-oxide-semiconductor-field-effect-transistor fabrication process sequence. On-chip circuit components, such as piezoresistive deflection sensors, deflection actuators, and amplifiers, are fabricated on the mirror-polished surface of the wafer, ensuring optimal performance. The tip fabrication process is based on anisotropic silicon etching at low temperature using a tetramethylammonium hydroxide solution. The anisotropic etching process has been optimized to ensure process controllability. Using the described process, complementary-metal-oxide-semiconductor-field-effect-transistor-based cantilevers with piezoresistive deflection sensors and integrated tips have been successfully fabricated. Force-distance curves and scanning images in constant-force mode have been recorded.

Journal Article↗