Biomaterial Database

Methodological aspects of tear flow determination by means of a radioactive tracer. 1977

T Sorensen, and F T Jensen

Theoretical considerations on a simplified biological system representing the tear pathways lead to the assumption of an exponential pattern of elimination of tracer substances from the conjunctival sac. The tracer used in the present study was technetium, Tc99m, as sodium pertechnetate. The detection system consisted of a gamma camera coupled to a digital system, a minicomputer and a magnetic tape unit. After instillation of 10 microliter normal saline solution containing Tc99m the decay of activity was followed by means of an activity-time function curve to which exponential curves were approximated by the computer. As a parameter for tear flow the fractional turnover rate was calculated from 7 to 15 min after instillation. An initial faster elimination was found in the first 7 min following instillation. Corrections for background radiation, evaporation of water and transconjunctival transport of Tc99m were estimated.

UI	MeSH Term	Description	Entries
D007765	Lacrimal Apparatus	The tear-forming and tear-conducting system which includes the lacrimal glands, eyelid margins, conjunctival sac, and the tear drainage system.	Lacrimal Gland,Nasolacrimal Apparatus,Conjunctival Sacs,Lacrimal Ducts,Lacrimal Punctum,Lateral Canthus,Medial Canthus,Apparatus, Lacrimal,Apparatus, Nasolacrimal,Canthus, Lateral,Canthus, Medial,Conjunctival Sac,Duct, Lacrimal,Gland, Lacrimal,Lacrimal Duct,Lacrimal Glands,Lacrimal Punctums,Punctum, Lacrimal,Sac, Conjunctival
D008722	Methods	A series of steps taken in order to conduct research.	Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D011877	Radionuclide Imaging	The production of an image obtained by cameras that detect the radioactive emissions of an injected radionuclide as it has distributed differentially throughout tissues in the body. The image obtained from a moving detector is called a scan, while the image obtained from a stationary camera device is called a scintiphotograph.	Gamma Camera Imaging,Radioisotope Scanning,Scanning, Radioisotope,Scintigraphy,Scintiphotography,Imaging, Gamma Camera,Imaging, Radionuclide
D003228	Conjunctiva	The mucous membrane that covers the posterior surface of the eyelids and the anterior pericorneal surface of the eyeball.	Bulbar Conjunctiva,Palpebral Conjunctiva,Plica Semilunaris of Conjunctiva,Plicae Semilunares of Conjunctiva,Tunica Conjunctiva,Conjunctiva, Bulbar,Conjunctiva, Palpebral,Conjunctivas
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013666	Tears	The fluid secreted by the lacrimal glands. This fluid moistens the CONJUNCTIVA and CORNEA.	Meibomian Lipids,Meibum,Lipid, Meibomian,Meibomian Lipid,Tear
D013667	Technetium	The first artificially produced element and a radioactive fission product of URANIUM. Technetium has the atomic symbol Tc, and atomic number 43. All technetium isotopes are radioactive. Technetium 99m (m	Technetium 99m,99m, Technetium