Biomedical subjects

Ernest U Conrad

Publications and source records attributed to Ernest U Conrad.

22 records · Page 2Linked to original sources

PubMed2002

Evaluation of chemotherapy response in pediatric bone sarcomas by [F-18]-fluorodeoxy-D-glucose positron emission tomography.

BACKGROUND: Response to neoadjuvant chemotherapy is a significant prognostic factor for osteosarcoma (OS) and the Ewing sarcoma family of tumors (ESFT). Conventional radiographic imaging does not discriminate between responding and nonresponding osseous tumors. [F-18]-fluorodeoxy-D-glucose (FDG) positron emission tomography (PET) is a noninvasive imaging modality that accurately predicts histopathologic response in patients with various malignancies. To describe the FDG PET imaging characteristics and to determine the correlation between FDG PET imaging and chemotherapy response in children with bone sarcomas, we reviewed our single institution experience. METHODS: Thirty-three pediatric patients with OS or ESFT with osseous primary sites were evaluated by FDG PET. All patients received standard neoadjuvant chemotherapy. FDG PET standard uptake values before (SUV1) and after (SUV2) chemotherapy were analyzed and correlated with chemotherapy response assessed by histopathology in surgically excised tumors. Twenty-six patients had SUV1, SUV2, and surgical excision. RESULTS: Although the mean SUV1 in children with OS or ESFT were similar (8.2. vs. 5.3, P = 0.13), mean SUV2 for OS patients was greater than the values for ESFT patients (3.3 vs. 1.5, P = 0.01). All ESFT patients and 28% of OS patients had a favorable histologic response to chemotherapy (>or= 90% necrosis). Combining ESFT and OS patients, both SUV2 and the ratio of SUV2 to SUV1 (SUV2:SUV1) were correlated with histologic response (P = 0.01 for both comparisons). CONCLUSION: FDG PET evaluation of pediatric bone sarcomas demonstrated significant alteration in response to neoadjuvant chemotherapy. SUV2 and SUV2:SUV1 correlated with histopathologic assessment of response and potentially could be used as a noninvasive surrogate to predict response in patients.

Adolescent↗

PubMed2002

RNA splicing mediated by YB-1 is inhibited by TLS/CHOP in human myxoid liposarcoma cells.

Human myxoid liposarcoma contains a characteristic t(12;16) chromosomal translocation that results in fusion of the N-terminal domain of the translocated in liposarcoma (TLS) protein to the C/EBP homologous protein (CHOP). TLS possesses structural motifs that suggest it may participate in RNA processing. We demonstrate that in human myxoid liposarcoma cells, wild-type TLS binds to RNA polymerase II (Pol II) via its N-terminal domain and to the transcription and translation factor Y-box binding protein-1 (YB-1) through its C-terminal domain. The liposarcoma fusion protein TLS/CHOP retains the ability to bind RNA Pol II but lacks the ability to recruit YB-1 due to replacement of the C-terminal domain of TLS by CHOP. In an in vivo splicing assay, YB-1 promotes splicing of adenovirus EIA pre-mRNA predominantly to the 13S isoform. The oncogenic TLS/CHOP fusion protein inhibits this splicing function of YB-1 in a dominant negative manner. When considered in conjunction with studies on other sarcoma fusion proteins, these data suggest that aberrant RNA splicing may be a common feature of human sarcomas.

Adenovirus E1A Proteins↗

PubMed2002

Banking of osteochondral allografts. Part I. Viability assays adapted for osteochondrol and cartilage studies.

The aim of this study was to adapt a reliable, reproducible and simple viability assay for cartilage and osteochondral studies. The previous assays (radioisotope uptake, assessment of matrix components, histological methods, oxygen consumption etc.) were complex, laborious, time consuming or suffer from difficulty of interpretation. MTT assay was chosen because it has been widely and successfully used in different cell and tissue studies, but has not been published on human solid articular cartilage. Fresh intact cartilage samples of human tali were tested to investigate the assay. The reliability of the MTT assay was also tested by an fluorescent dye combination. The MTT assay is based on the production of purple formazan pigment from methyltetrazolium salt by the mitochondrial enzymes of viable chondrocytes. The enzyme kinetics of the reaction was also investigated because it was unknown in the case of cartilage. The amount of pigment formed can be measured by spectrophotometry after extraction by methyl cellosolve. The color density is proportional to mitochondrial enzyme activity, reflecting the number of viable chondrocytes. The optimal reagent concentration, biopsy size, and incubation period were established. There is a linear relationship between the cartilage weight and the pigment production activity. A 9.8% nonspecific raction was observed in the negative controls. The enzyme kinetics of the reaction was also investigated. The MTT clevage up to 0.1% (w/v) follows the Michaelis kinetics. We calculated the Michaelis constant (2835 +/- 130 microM), the maximal velocity (36 +/- 3.2 x 10(-5)microMsec(-1)) and the velocity constant (1.27 +/- 0.2 x 10(-7)sec(-1)) of the reaction. The latter is a significant marker for each tissue type. The viability of cartilage was also assessed and calculated by a fluorescent dye combination comprising 1 microg/ml propidium iodide (PI) and 4 microM/ml SYTO-16 stains. The PI stains dead cells (red fluorescence), the SYTO-16 stains live cells (green fluorescence). The staining can be visualised simultaneously, and the live/dead ratio can be calculated by image analysis software from saved image files. The MTT assay is a simple, non-expensive, efficient, reliable, reproducible, sensitive viability test for cartilage studies. The MTT reduction assay and the staining method were corrobative.

Journal Article↗

PubMed2002

Banking of osteochondral allografts, Part II. Preservation of Chondrocyte Viability During Long-Term Storage.

One of the most important factors concerning the successful clinical outcome after transplantation of osteochondral allografts is the viability of the cartilage.The viability of cryopreserved cartilage is quite poor, 20-30% cell survival has been published. The purpose of this study was to develop a new storage method which improves the chondrocyte viability. The talus of cadaveric donors was used as a model tissue to compare human osteochondral allograft cartilage viability following cryopreservation with that remaining after prolonged refrigerated storage. Full-thickness cartilage punch biopsies had been cryopreserved, and tali were divided into two matched groups and stored in TCM for 60 days at +4 degrees C, either with or without regular medium replacement. The cartilage of each graft was biopsied and assayed for viability on every third day by the MTT reduction assay. During 4 degrees C storage, a recurring pattern of large fluctuations in apparent cartilage viability was observed in every stored graft, with or without medium replacement. These fluctuations did not appear in control specimens of either fresh or cryopreserved human skin that were assayed in parallel with the cartilage biopsies, so the viability fluctuation seems an intrinsic property of the cartilage in these conditions. Cartilage stored for 60 days at +4 degrees C showed significantly higher viability (35.2 +/- 3.3 %) than fresh cartilage that had been cryopreserved (21.6 +/- 1.8 %). This was true even when cryopreserved and thawed cartilage was subjected to a 3 day post thaw incubation under presumably favorable conditions (17.7 +/- 1.6 %). These viability assay results, (reflective of intracellular metabolic activity), were corroborated by the fluorescent dye mixture SYTO-16 and propidium iodide. The data indicate that long-term stored refrigerated cartilage appears to retain a viability higher than that of cryopreserved cartilage for up to and perhaps beyond 60 days of storage. There was no viability index difference between the medium replaced and non-replaced groups. Although an exceptional result, in one individual case, more than 65% viable cells could be detected in the talar cartilage after 60 days storage at +4 degrees C.

Journal Article↗