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Biomedical subjects

R E Cunningham

Publications and source records attributed to R E Cunningham.

At least 19 recordsLinked to original sources
PubMed1995

Lamellar-phase polymorphism in interdigitated bilayer assemblies.

Bilayers composed of 1-octadecanoyl-2-decanoyl-sn-glycero-3-phosphocholine (C(18)C(10)PC) adopt a mixed-interdigitated gel-phase packing where the short chains of the C(18)C(10)PC molecules pack end-to-end while their long chains span the entire hydrocarbon width of the bilayer. Calorimetric cooling scans of freshly prepared hand-shaken bilayer suspensions of C(18)C(10)PC exhibit a single exothermic phase transition at 14.6 degrees C, whereas suspensions incubated at temperatures below 2 degrees C for several days exhibit an additional phase-transition exotherm at 17.9 degrees C. Calorimetric and electron microscopic evidence is presented that low-temperature incubation of C(18)C(10)PC bilayer suspensions composed of liposomes of heterogeneous size leads to the conversion of those liposomes in the suspension below about 0.2 microns in diameter into planar lamellar sheets. These lamellar sheets are the origin of the phase-transition exotherm at 17.9 degrees C, whereas the phase-transition exotherm at 14.6 degrees C arises from the liposomes in the suspension. We also show that phosphatidylcholine bilayer suspensions, induced to interdigitate by ethanol, exhibit a similar thermotropic behavior. The implication of these findings for the reversibility of interdigitated gel to liquid-crystalline phase transitions and the role of phospholipid molecular geometry in the formation of interdigitated bilayers are addressed.

Calorimetry, Differential Scanning↗
PubMed1994

Proliferating-cell nuclear antigen immunocytochemistry in the evaluation of gastrointestinal smooth-muscle tumors.

Current methods do not provide a way always to distinguish benign from malignant gastrointestinal smooth-muscle tumors. We compared immunocytochemical assessment of proliferating-cell nuclear antigen expression with flow cytometry and mitotic figure-counting as a prognostic marker in 85 gastrointestinal smooth-muscle tumors. Although proliferating-cell nuclear antigen expression was associated with poor prognosis in univariate statistical analysis, it was not significant in multivariate proportional hazards models that included either the mitotic index or aneuploidy of the flow-cytometric G2M peak. We conclude that proliferating cell nuclear antigen assessment is not warranted in the routine evaluation of gastrointestinal smooth-muscle tumors.

Biomarkers, Tumor↗
PubMed1993

Predicting prognosis of gastrointestinal smooth muscle tumors. Role of clinical and histologic evaluation, flow cytometry, and image cytometry.

Both flow cytometry (FCM) and morphometry have been proposed as techniques for predicting the prognosis of gastrointestinal (GI) smooth muscle tumors (SMTs). In particular, DNA aneuploidy by FCM has been associated with high histologic grade and shortened survival, whereas the DNA index determined by image cytometry has been proposed as a criterion for the diagnosis of malignancy. To further define the potential roles of these two techniques, we performed a variety of morphometric and FCM measurements on paraffin blocks from 122 patients with GI SMTs, with a median follow-up period of 6 years, together with assessments of tumor size and mitotic activity. None of the morphometric measurements (nuclear perimeter, area, form factor, longest diameter, average ferret diameter, equivalent diameter, and DNA index) was a significant prognostic factor when analyzed using a univariate Cox model. In contrast, the flow cytometric mean channel number, the fraction of cells in G2M, aneuploidy of the G0/G1 peak, aneuploidy of the G2M peak, tumor size, and mitotic activity index were statistically significant in univariate models, together with the patient age and sex, and whether or not the patient presented with metastases. In a multivariate model, > 10 mitotic figures per 50 high-power fields and metastases indicated a poor prognosis. If metastasis was not allowed to enter the model, the mitotic index and aneuploidy of the G2M peak portended a poor prognosis.

Female↗
PubMed1993

bcl-2 rearrangement in Hodgkin's disease. Results of polymerase chain reaction, flow cytometry, and sequencing on formalin-fixed, paraffin-embedded tissue.

We examined 81 cases of Hodgkin's disease for evidence of the t(14;18) translocation, using the polymerase chain reaction assay on lysates of formalin-fixed, paraffin-embedded tissue. Seven of 74 amplifiable cases (9%) were positive for the translocation, which involves the bcl-2 oncogene and the immunoglobulin heavy chain gene. Two of these cases were sequenced and the breakpoints had the same pattern found in follicular lymphoma. The nuclei from one of the cases were sorted into large and small subpopulations. The t(14;18) signal was more intense in the large nucleus subpopulation, which contained a greater proportion of Reed-Sternberg-like nuclei. These results are consistent with the hypothesis that Reed-Sternberg cells carry the translocation, but they do not exclude the possibility that the translocation is found in cells representing the reactive component of Hodgkin's disease. The results also demonstrate that routinely processed material is suitable for polymerase chain reaction-based analysis of translocations, although the sensitivity is reduced 10- to 100-fold, compared with fresh tissue.

Base Sequence↗