Instantaneous peripheral vascular resistance changes rendered by critical closing phenomenon.
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Animals↗
Biomedical subjects
R M Olson
Publications and source records attributed to R M Olson.
Aortic blood pressure and velocity as a function of time and position.
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Animals↗
Evaluation of collagen crosslinking techniques.
The properties of collagen films crosslinked by physical and chemical techniques were compared to the properties of films crosslinked with glutaraldehyde (GTA). Physical techniques studied include exposure to short wave (254 nm) u.v. irradiation and severe dehydration. Chemical techniques studied include immersion of collagen films in aqueous solutions of cyanamide or GTA. Collagen films exposed to combinations of aqueous solutions of cyanamide and severe dehydration had moduli of elasticity, swelling ratios and resistance to bacterial collagenase similar to films crosslinked with GTA. Theoretical calculations based on amino acid composition indicate that approximately seven times as many amino acid residues are capable of forming crosslinks using cyanamide or severe dehydration procedures as compared to GTA crosslinking. In addition, using severe dehydration or cyanamide forms crosslinks involving both amino and carboxyl residues which may allow these procedures to act synergistically. Based on our studies this two-step procedure effectively crosslinks collagen-based biomaterials while the only by-product of this reaction is water-soluble urea. Preliminary biocompatibility studies suggest that this crosslinking procedure may allow for pronounced tissue ingrowth.
Amino Acids↗
Human carotid artery diameter and flow by a noninvasive technique.
This paper presents a technique tested in vitro and in dogs and used in humans to measure carotid artery blood flow continuously by placing a transducer on the skin over the artery. The tranducer consists of a pulse echo crystal used to locate the carotid artery and measure its diameter and wall velocity. It also has a pair of Doppler shift crystals used to measure the velocity of the artery wall and blood flow in the vessel. It was found that the pulsatile artery wall distension was between 8 and 13 percent of the diastolic diameter. The peak blood flow varied inversely with pulse rate. Occlusion of one carotid resulted in an increase in diastolic but not systolic flow in the other.
Adult↗