Biomedical subjects

R C Tschumper

Publications and source records attributed to R C Tschumper.

6 recordsLinked to original sources

PubMed1990

Glycosaminoglycans of human trabecular meshwork in perfusion organ culture.

The synthetic profile of glycosaminoglycans (GAGs) of human trabecular meshwork in perfusion organ culture was studied in a series of 34 human eyes. The anterior segments of these eyes were cultured for periods of two to 28 days and received medium containing 3H-glucosamine and 35S-sulfate during the final 48 hours of culture. The meshwork was then dissected and the GAGs isolated and subjected to sequential enzyme digestion. Active labelling of hyaluronic acid, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparan sulfate was found in all time periods. Eyes cultured seven and 14 days had similar incorporation profiles to "fresh" eyes (cultured 48 hours to allow for labelling). Eyes cultured 21 days showed an increase in dermatan sulfate labelling and a slight decrease in keratan sulfate labelling when compared with "fresh" eyes. Light microscopic autoradiography confirmed the trabecular meshwork incorporation of the radiolabelled precursors at all time periods. Thus, the trabecular meshwork remains metabolically active and GAG synthetic profiles remain reasonably similar to fresh eyes for up to three weeks in a perfusion organ culture system. This system may serve as a model for future studies of human trabecular meshwork GAGs.

Adult↗

PubMed1990

Human trabecular meshwork phagocytosis. Observations in an organ culture system.

Perfusion organ culture of the trabecular meshwork was used to study the phagocytic ability of human trabecular cells. Cultured eyes were challenged with blood, latex microspheres, or zymosan particles for periods of 1 hour to 7 days. Trabecular cells were capable of ingesting all three types of particles. The presence of a foreign particle did not necessarily induce a phagocytic response, however, as free particles were seen in the intertrabecular spaces and Schlemm's canal. In contrast to studies in animals which indicate trabecular cell migration from the eye may play a role in the removal of foreign debris, limited human trabecular cell migration was observed. The effect of the culture process on trabecular cell phagocytosis was also studied, using adult cats. One eye received a phagocytic challenge in vivo with the fellow eye later receiving the phagocytic challenge in vitro. Phagocytosis was demonstrated in each eye, although more cells were involved with phagocytosis in vivo. The additional cells involved in vivo may have been recruited by an accompanying inflammation. Organ culture of human trabecular meshwork may be useful in the study of trabecular cell phagocytosis, and it allows separation of the effects of inflammation from the potential effects of phagocytosis itself.

Aged↗

PubMed1990

Stimulation of cell division by argon and Nd:YAG laser trabeculoplasty in cynomolgus monkeys.

Although laser treatment of the trabecular meshwork is the most common form of surgery for glaucoma, the tissue response to this therapy is still incompletely understood. We applied argon or Nd:YAG laser to the trabecular meshwork of six monkeys. Cell division was identified by injecting tritiated thymidine into the anterior chamber 24 hr after laser application. Autoradiography of tissue sections revealed significantly more labelled cells in eyes treated with laser than in the untreated controls. In addition, cells in neighboring tissues such as iris, ciliary body and sclera showed labelling in association with laser application. Furthermore, comparison of argon-induced lesions with those caused by pulsed Nd:YAG suggests that there are quantitative and qualitative differences in the response of trabecular meshwork and surrounding tissues to these two forms of laser energy.

Animals↗

PubMed1990

Trabecular meshwork cellularity. Differences between fellow eyes.

The difference in trabecular meshwork cellularity between fellow eyes was determined in a series of seven pairs of normal human eyes. Variations in cellularity between different quadrants of individual eyes also were determined. Characterization of these differences and development of appropriate sampling techniques to determine trabecular cellularity has become important in light of recent studies that find a decrease in trabecular cell numbers with age and with primary open-angle glaucoma, and the apparent stimulation of trabecular cell division by laser trabeculoplasty. The difference in absolute cell numbers (nuclei per section) between fellow eyes was 12.8% +/- 4.3% (standard error of the mean, SEM). The difference in cellularity (nuclei per solid tissue area) was 9.4% +/- 4.5% (SEM) in a subgroup of five pairs of these eyes. The coefficient of variation between different quadrants of an eye was 18.4% for absolute cell numbers and 17.3% for cellularity for the entire group of eyes. Sample size calculations indicate that for future studies, four pairs of eyes would be needed to detect a 20% difference in absolute cell numbers between fellow eyes and three pairs needed for detecting a similar difference in cellularity (alpha = 0.05, beta = 0.1). At least two quadrants per eye should be examined.

Aged↗

PubMed1989

The effect of organ culture on human trabecular meshwork.

The effect of organ culture on the trabecular meshwork was studied in a series of human eyes using a perfusion culture system. One eye of a pair was cultured while the fellow eye was immediately fixed in glutaraldehyde. Culture periods ranged from 2 to 28 days, during which a mean intraocular pressure of 27 mmHg +/- 15 was maintained. The perfused culture medium appeared to leave the eye via Schlemm's canal and collector channels, mimicking the in vivo situation. The trabecular meshwork was well maintained with this system in 21 of 25 eyes. Cells remained in position on trabecular lamellae, cellular organelles usually remained normal, and the lamellae remained intact. Culture-induced changes were noted, with some cells developing intracytoplasmic lipid vacuoles and other cells developing swollen mitochondria. In addition, scattered focal cell necrosis was observed, most often in the uveal meshwork. Meshwork cellularity (nuclei:solid tissue) was determined with an image analysis system; there was an average cell loss of 20-40% in the cultured eyes as compared to their respective fellow control eyes. Overall, organ culture appears to maintain the human trabecular meshwork for at least 28 days, allowing controlled experimental studies to be performed.

Aged↗

PubMed1987

Human trabecular meshwork organ culture. A new method.

A new method has been developed for organ culture of human trabecular meshwork. Human eyebank eyes are sectioned at the equator and lens and vitreous are removed. The anterior segments are placed in a modified culture dish, cornea side up, and then sealed in place. Culture media (Dulbecco's modified Eagle media) are perfused through a cannula built into the bottom of the dish. The sealed system forces media to flow through the trabecular meshwork, Schlemm's canal, and exit through the normal limbal pathways. Intraocular pressure can be maintained at normal (or elevated) levels throughout the culture period. Corneal clarity is maintained. Trabecular cells remain in normal position on trabecular beams and maintain many of their usual morphologic characteristics. Cultures appear to be viable for up to 4 weeks. This technique should allow study of intact human trabecular meshwork in a controlled experimental fashion.

Aged↗