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Biomedical subjects

Jonathan Adams

Publications and source records attributed to Jonathan Adams.

4 recordsLinked to original sources

Components for high speed atomic force microscopy.

Many applications in materials science, life science and process control would benefit from atomic force microscopes (AFM) with higher scan speeds. To achieve this, the performance of many of the AFM components has to be increased. In this work, we focus on the cantilever sensor, the scanning unit and the data acquisition. We manufactured 10 microm wide cantilevers which combine high resonance frequencies with low spring constants (160-360 kHz with spring constants of 1-5 pN/nm). For the scanning unit, we developed a new scanner principle, based on stack piezos, which allows the construction of a scanner with 15 microm scan range while retaining high resonance frequencies (>10 kHz). To drive the AFM at high scan speeds and record the height and error signal, we implemented a fast Data Acquisition (DAQ) system based on a commercial DAQ card and a LabView user interface capable of recording 30 frames per second at 150 x 150 pixels.

Animals↗

The use of knockout mouse technology to achieve tissue selective expression of angiotensin converting enzyme.

The resin angiotensin system (RAS) plays an essential role in blood pressure regulation and electrolyte homeostasis. The effecter peptide of the RAS, angiotensin II, is produced by angiotensin converting enzyme (ACE) in multiple tissues. Genetic deletion of ACE in mice resulted a phenotype of low blood pressure, anemia and kidney defects. However, it is not clear whether the lack of the systemic or the local production of angiotensin II caused these defects. To understand the role of local angiotensin II production, we developed a method to achieve tissue specific ACE expression through homologous recombination. In this review, we discuss mouse models in which endothelial ACE was eliminated and replaced by hepatic ACE. These studies suggest that both circulating angiotensin II and local angiotensin II production play a role in angiotensin II generation; the elimination of local angiotensin II generation up-regulates systemic production and maintains physiologic homeostasis.

Angiotensin II↗