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Biomedical subjects

R Gaddis

Publications and source records attributed to R Gaddis.

4 recordsLinked to original sources
PubMed1987

Acceleration of coronary collateral development by heparin in conscious dogs.

We evaluated whether heparin pretreatment accelerates the development of coronary collateral vessels induced by repeated, brief coronary occlusions. Sixteen dogs were instrumented for the measurement of subendocardial segment length in the area perfused by the left circumflex coronary artery (LCCA), LCCA flow and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the LCCA. Two min coronary occlusions (CO) at rest were repeated hourly until there was no reduction in ischemic segment systolic shortening at the end of CO and negligible reactive hyperemia following the release of CO. Eight control dogs developed collaterals sufficient for resting myocardial oxygen requirements in the LCCA region by 129 +/- 45 (SD) CO. The remaining 8 dogs given heparin daily developed collaterals by 81 +/- 33 CO (p less than 0.05). Thus, in the presence of severe myocardial ischemia known to promote collateralization, heparin accelerated the development of coronary collaterals.

Animals↗
PubMed1977

A procedure for dissociating Ayre scrape samples.

The dissociation of cervical cell suspensions after various chemical and enzymatic treatments was monitored by using the Centrifugal Cytology rotor to produce glutaraldehyde-fixed dispersions on conventional microscope slides and subsequent Pap staining. A special program was written in RPG II to record and analyze the results of the dissociation experiments in terms of white blood cells and the true cervical cells ("other cells"), and the degree of dissociation and recovery of both classes of cells. Since accurate differential counts on the untreated Ayre scrapes were difficult, the samples were syringed gently to break up the large or adventitious clumps. Cumulated results from control preparations indicate that the white blood cells and "other cells" are composed respectively of 92 and 63% single cells. The cells were further dissociated by: dissolving the cervical mucin sequentially with dithiothreitol and iodoacetic acid; depolymerizing the nucleohistone gel with ribonuclease; solubilizing the desmosomes with EDTA; removing the remaining cellular agglutinins with Varidase; and finally mechanical dispersion by hypertonic shock. The optimum procedure for dissociation involves the use of ribonuclease, dithiothreitol, iodoacetic acid EDTA, Varidase and sucrose shock. The white blood cells are now monodisperse and 81% of the "other cells" are found as single cells. If nuclear separation by two diameters is considered sufficient 98% of the "other cells" are single. The slide preparations are now sufficiently good that a scanning system is feasible.

Autoanalysis↗
PubMed1977

Optimization of the binding of dissociated exfoliated cervico-vaginal cells to glass microscope slides.

In order to monitor the development of a cell dissociation technique, it was essential to utilize the Centrifugal Cytology rotor to produce glutaraldehyde-fixed even cellular dispersions. The Cytology rotor has been improved to insure rapid alignment with the centrifugal field during both acceleration and deceleration, and the fixative is now delivered to the surface of the slide. The dissociation of the cells results in a loss of their adhesion to glass slides. Three bonding agents were tested: (a) Poly-L-Lysine; (b) Mayer's albumin fixative; (c) positively charging the slides with a silicone coating. The results with 65% albumin-coated slides were clearly superior to the other two. The addition of a postfixation step of 95% ethanol/4% polyethylene glycol did not significantly affect the recovery of the cells, but did eliminate some unevenness in the Centrifugal Cytology preparations, flattened the cells and expedited the procedure.

Albumins↗