ABSTRACT
A capacitive measurement of the biosignals is a very comfortable and unobtrusive way suitable for long-term and wearable monitoring of health conditions. This type of sensing is very susceptible to noise from the surroundings. One of the main noise sources is power-line noise, which acts as a common-mode voltage at the input terminals of the acquisition unit. The origin and methods of noise reduction are described on electric models. Two methods of noise removal are modeled and experimentally verified in the paper. The first method uses a passive capacitive grounding electrode, and the second uses an active capacitive Driven Right Leg (DRL) electrode. The effect of grounding electrode size on noise suppression is experimentally investigated. The increasing electrode area reduces power-line noise: the power of power-line frequency within the measured signal is 70.96 dB, 59.13 dB, and 43.44 dB for a grounding electrode area of 1650 cm2, 3300 cm2, and 4950 cm2, respectively. The capacitive DRL electrode shows better efficiency in common-mode noise rejection than the grounding electrode. When using an electrode area of 1650 cm2, the DRL achieved 46.3 dB better attenuation than the grounding electrode at power-line frequency. In contrast to the grounding electrode, the DRL electrode reduces a capacitive measurement system's financial costs due to the smaller electrode area made of the costly conductive textile.
ABSTRACT
Collagen type IV in the lamina propria mucosae is one of the main components of the basement membrane of normal and transitional colon mucosa. The aim of the present study was to assess the use of anti-collagen type IV antibodies in the evaluation of biological activity of epithelial tumours of the colon. Formalin-fixed and paraffin-embedded specimens of polyps and carcinomas of the colon from 14 patients were analyzed. In transitional mucosa around epithelial tumours, only minor deformities of the evenly thick collagen type IV-containing basement membranes were found. This pattern was different in polyps where collagen type IV-positive basement membrane components extended between basolateral membranes of epithelial cells. Local changes of collagen type IV positivity in basement membranes of polyps were observed. Positivity of epithelial basement membranes disappeared in adenocarcinomas but there was an increased positivity in fibrillar components of stroma. Basement membranes of microvessels in lamina propria mucosae were also positive for collagen type IV. Similar observations were made in the stroma of polyps. Our results indicate that loss of collagen type IV in basement membranes of adenocarcinomas is related to loss of differentiation and the malignant potential of epithelial tumours of colon.
