Biomedical subjects

S M Hewitt

Publications and source records attributed to S M Hewitt.

23 records · Page 2Linked to original sources

PubMed1988

Infiltration of interleukin-2-inducible killer cells in ascitic fluid and pleural effusions of advanced cancer patients.

Using ascitic fluid or pleural effusion obtained from 13 ovarian or metastatic breast cancer patients, we separated tumor cells from effusion-associated lymphocytes (EAL) with Percoll density centrifugation. Lymphocytes were incubated with recombinant interleukin 2 (IL-2) for 3-4 days and then assessed for tumoricidal activity in a 51chromium-release assay. The IL-2-activated EAL were found to lyse autologous fresh tumor cells, as well as allogeneic fresh tumor cells and FMEX tumor cells, a melanoma cell line which is resistant to natural killer cell activity but is sensitive to lysis by lymphokine-activated killer cells. There was little or no tumoricidal activity seen in freshly isolated EAL or in EAL which were cultured in medium without IL-2. Phenotypically, the IL-2-activated EAL were largely CD3-, although some cytolytic activity was found in CD3+ populations. Also, most activity was found in cells positive for CD2 (OKT11) and CD16 (Leu 11b), and negative for the monocyte marker Leu M3. These results indicate that the activated cell types found in EAL were predominantly natural killer/lymphokine-activated killer-like with a small contribution from T-cells. Finally, EAL were readily activated by IL-2 in medium containing autologous effusion fluid, indicating that in situ activation of tumoricidal activity by IL-2 can occur in the face of potentially inhibitory substances or cells that may exist in the effusions. Direct introduction of IL-2 may therefore be a potential therapeutic modality of effusion-forming cancers.

Adult↗

PubMed1985

Process auditing in long term care facilities.

The ECC tool development and audit experiences indicated that there is promise in developing a process audit tool to monitor quality of care in nursing homes; moreover, the tool selected required only one hour per resident. Focusing on the care process and resident needs provided useful information for care providers at the unit level as well as for administrative personnel. Besides incorporating a more interdisciplinary focus, the revised tool needs to define support services most appropriate for nursing homes, includes items related to discharge planning and increases measurement of significant others' involvement in the care process. Future emphasis at the ECC will focus on developing intervention plans to maintain strengths and correct deficiencies identified in the audits. Various strategies to bring about desired changes in the quality of care will be evaluated through regular, periodic monitoring. Having a valid and reliable measure of quality of care as a tool will be an important step forward for LTC facilities.

Chicago↗

PubMedDate not supplied

Isolated organ perfusion does not result in systemic microembolization of tumor cells.

BACKGROUND: Isolated organ perfusion with hyperthermia and melphalan with or without tumor necrosis factor-alpha has been effectively used to treat regionally confined, unresectable malignancies of both the limb and liver. Many patients, however, will eventually relapse at distant sites. We used reverse transcription-polymerase chain reaction (RT-PCR) to determine whether significant tumor microembolization occurs in patients undergoing isolated limb perfusion (ILP), isolated hepatic perfusion (IHP), or hepatic resection. METHODS: Primers specific for the human tyrosinase gene or carcinoembryonic antigen gene were designed for RT-PCR to screen melanoma or colon adenocarcinoma, respectively. RNA from human melanoma lines (Pmel and 1286) and human colon adenocarcinoma lines (H508 and HT29) were used to generate positive control cDNA. Normal human blood was inoculated with tumor cells at concentrations that ranged from 10(-2) to 10(5) tumor cells/ml of blood to define the sensitivity. Systemic and perfusate blood samples were drawn from 15 patients (8 patients underwent IHP, 5 patients underwent ILP, and 2 patients underwent resection) before the start of the operation, immediately before and during the perfusion, and postoperatively. Mononuclear cell fractions were separated from the blood samples and RNA was extracted for the RT-PCR assay. Standard primers for human beta-actin were used to confirm that cDNA was generated after the RT reaction. RESULTS: RT-PCR assay sensitivity was determined to be 10 tumor cells/ml of whole blood. Of the 8 IHP patients, 6 had colon metastases and 2 had ocular melanoma metastases to the liver. All 5 ILP patients had in transit melanoma of the extremity. Two patients with colon metastases to the liver were found to have resectable disease. There were no detectable circulating tumor cells in the systemic circulation either preoperatively or postoperatively in all 15 patients that were screened. CONCLUSIONS: RT-PCR is a highly sensitive method of detecting tumor cells in perfusate or blood. Manipulation of the limb or liver followed by resection or isolated hyperthermic perfusion does not cause detectable release of circulating tumor cells. The late development of distant metastases observed in many of these patients does not correlate with the ability to measure circulating tumor cells during regional therapy.

Adenocarcinoma↗

PubMedDate not supplied

Differentially spliced exon 5 of the Wilms' tumor gene WT1 modifies gene function.

The Wilms' tumor gene WT1 encodes a zinc-finger transcription factor that functions as a tumor suppressor gene and repress transcription of a number of growth factors and proto-oncogenes. In the developing kidney, WT1 expression peaks at the onset of the mesenchyme-to-epithelium transition and is required for epithelial differentiation. WT1 mRNA undergoes alternative splicing at two sites, resulting in four mRNA species and proteins expressed in constant ratios. The first alternative splice results in the presence or absence of exon 5, which is 51 nucleotides long and encodes 17 amino acids between the amino-terminal, proline-rich transcriptional repression domain and the carboxy-terminal DNA-binding zinc-fingers. We used cell-proliferation assays to determine the effect of exon 5 on WT1 function. Isoforms of WT1 without exon S repressed cell growth. WT1 isoforms with exon 5 slowed cell growth to a lesser extent but resulted in altered cellular morphology. These results provide evidence that WT1 splice isoforms differentially regulate cell proliferation and initiate the mesenchyme-to-epithelium transition during metanephric development.

Alternative Splicing↗

PubMedDate not supplied

Transcriptional activation of the bcl-2 apoptosis suppressor gene by the paired box transcription factor PAX8.

The bcl-2 proto-oncogene suppresses apoptosis in a variety of cell types and is essential for normal renal development. PAX8 is a member of the paired box class of transcription factors and is developmentally regulated. bcl-2 and PAX8 are both expressed in the kidney during development and throughout life, demonstrating a nearly identical pattern of expression. We used transient transfection reporter assays and electrophoretic mobility shift assays to test PAX8 transcriptional regulation of bcl-2. PAX8 transcriptionally activates the bcl-2 promoter and binds to promoter sequences in vitro. These findings establish that PAX8 can transcriptionally regulate bcl-2 and suggest that suppression of apoptosis is an important event in the development and maintenance of renal tubular epithelial structures.

Apoptosis↗