Biomedical subjects

J H Yim

Publications and source records attributed to J H Yim.

9 recordsLinked to original sources

PubMed2000

Papillary thyroid cancer.

Papillary thyroid cancer is the most common neoplasm of the thyroid gland. Surgical resection is the cornerstone of therapy. There is controversy regarding the extent of resection, ranging from thyroid lobectomy plus isthmusectomy to total thyroidectomy, but in experienced hands total thyroidectomy has many significant advantages over a lesser operation. Nonoperative therapy has no role as primary therapy for papillary thyroid cancer, but can be used in conjunction with surgery to improve outcome. Radioiodine in patients who have received total thyroidectomy can be used to identify residual occult tumor, recurrence, and metastasis, and can also be used to ablate the neoplasm, resulting in a substantial cure rate. Thyroid hormone is needed as replacement after total thyroidectomy, but can also be given as thyroid-stimulating hormone suppression, which may have an adjunctive benefit after resection.

Carcinoma, Papillary↗

PubMed1999

Enhancing in vivo tumorigenicity of B16 melanoma by overexpressing interferon regulatory factor-2: resistance to endogenous IFN-gamma.

We investigated the role of interferon (IFN) regulatory factor-2 (IRF-2) as an oncoprotein in vivo, opposing endogenous IFN-gamma suppression of tumor growth. Using syngeneic IFN-gamma knockout mice, we show that endogenous IFN-gamma slows growth of the mouse melanoma cell line B16-F10 in immunocompetent mice, suggesting that tumor cell resistance to IFN-gamma may lead to greater tumorigenicity. IRF-2 is a nuclear transcription factor induced by IFN-gamma that represses numerous IFN-inducible genes, including genes that regulate cell growth, in opposition to the transcriptional activator IRF-1. B16-F10 has a marked growth inhibitory response to IFN-gamma in vitro and has very little IRF-2 induction compared with other murine tumor cell lines. We engineered B16-F10 cells to stably overexpress murine IRF-2. In vitro, these transfected cells showed a marked resistance to the growth-inhibitory effect of IFN-gamma. In normal mice the IRF-2-transfected cells grew much faster than control tumors. In syngeneic IFN-gamma knockout mice, control cells grew at a rate similar to that of IRF-2-transfected cells, implicating resistance to endogenous IFN-gamma as playing the major role in enhanced growth of IRF-2-transfected tumors in intact mice. These experiments demonstrate that (1) IRF-2 enhances B16 melanoma growth and increases resistance to IFN-gamma in vitro, and (2) IRF-2 opposes the growth suppression mediated by endogenous IFN-gamma in vivo.

Animals↗

PubMed1998

Prospective study of the utility of somatostatin-receptor scintigraphy in the evaluation of patients with multiple endocrine neoplasia type 1.

BACKGROUND: Neuroendocrine tumors (NETs) are a potentially lethal component of multiple endocrine neoplasia type 1 (MEN 1). Somatostatin receptor scintigraphy (SRS) can be used to localize NETs and evaluate patients for extraduodenopancreatic disease; its utility in managing MEN 1 is undefined. METHODS: All patients with MEN 1 evaluated by SRS from April 1994 to November 1997 are reported. SRS findings were correlated with other imaging studies and operative findings. RESULTS: Thirty-seven SRS studies were performed in 29 patients with MEN 1. SRS identified occult tumor in 36% (4/11) of patients with only biochemical evidence of NET; 2 patients went on to resection. SRS showed tumor in 79% (15/19) of patients with computed tomography (CT)-demonstrated tumor; 30% (6/20) of the SRS lesions were occult on CT. Conversely, 55% (16/29) of CT-identified lesions were occult on SRS. SRS found distant disease in 21% (6/29) of patients. In patients who had previous operations, SRS found tumor in 40% (4/10) of patients, again with both new positive and false-negative results compared with other imaging. SRS also had 3 important false-positive results, including 1 patient who had laparotomy with no tumor identified. CONCLUSIONS: SRS is useful in identifying otherwise occult NETs in patients with MEN 1 and can substantially alter management. However, SRS also has significant false-positive and false-negative results that demand correlation with other studies.

Adult↗

PubMed1997

IFN regulatory factor-1 gene transfer into an aggressive, nonimmunogenic sarcoma suppresses the malignant phenotype and enhances immunogenicity in syngeneic mice.

IFN-gamma has a direct antitumor effect on many tumor cell lines mediated through the IFN-gammaR. One effect of IFN-gamma is to induce the nuclear transcription factor IFN regulatory factor-1 (IRF-1), which may function as a tumor suppressor. In this study, mouse IRF-1 cDNA under a high constitutive expression promoter was transfected into the highly aggressive, nonimmunogenic MCA 101 murine sarcoma. Clones were obtained by G418 selection and screened for IRF-1 mRNA expression by reverse transcriptase-PCR (RT-PCR). High expression clones had high levels of two MHC class I proteins (H-2Kb and H-2Db) on the cell surface that correlated with increased levels of class I mRNA by RT-PCR. Furthermore, these clones also had increased levels of MHC class II protein (I-Ab), which correlated with increased levels of one subunit of class II mRNA by RT-PCR. IRF-1-expressing clones had markedly diminished cell growth in vitro and decreased anchorage-independent growth in a soft agar assay. These clones also demonstrated markedly prolonged tumor latency and slowed growth in syngeneic C57BL/6 mice. IRF-1 gene-transfected cells had shortened tumor latency and formed faster growing tumors in gamma-irradiated immunodeficient mice compared with results in immunocompetent mice. Mice immunized with IRF-1-transfected cells were protected against subsequent challenge with IRF-1 transfected cells and also demonstrated greater tumor latency and slower tumor growth against subsequent challenge with untransfected cells compared with mice immunized with empty vector-transfected cells. These studies demonstrate a tumor suppressor effect of IRF-1, which acts in vivo through both partial reversion of the malignant phenotype and enhanced immune recognition and may play a role in the antitumor effects of IFN-gamma.

Animals↗

PubMed1997

Underlying pathology in mammary Paget's disease.

BACKGROUND: Management of patients with mammary Paget's disease is controversial; recent recommendations range from primary radiotherapy to modified radical mastectomy. This review correlates associated breast findings with disease stage and outcome to help guide evaluation and treatment. METHODS: Retrospective review of clinical, mammographic and pathologic data from 38 women with mammary Paget's disease treated between 1979 and 1995 was performed. Mastectomies were performed on all but two patients with the entire breast and lymph nodes evaluated for histopathologic evidence of carcinoma. RESULTS: Underlying carcinoma (ductal carcinoma in situ and/or invasive ductal cancer) was found in most patients (92%) even when no palpable mass was evident (85%); this carcinoma is often multifocal (73%). Mammography fails to identify the underlying disease in many patients with no palpable mass and multifocal underlying disease (64%). Patients with Paget's disease and a palpable mass have a much greater incidence of invasive cancer, multifocal lesions, and positive lymph nodes, and have worse survival. CONCLUSIONS: Although some patients with Paget's disease might be well treated by breast conservation therapy, many patients have underlying multifocal carcinoma (including invasive cancer), which can be inapparent by examination and mammography. Selecting candidates with disease amenable to complete excision without mastectomy is problematic.

Adult↗

PubMed1996

Mammographically detected breast cancer. Benefits of stereotactic core versus wire localization biopsy.

OBJECTIVE: The authors evaluated the differences between stereotactic core needle biopsy (SCNBx) and needle localization surgical biopsy (NLBx) in cost and treatment course for patients with mammographically detected breast cancer. SUMMARY BACKGROUND DATA: Stereotactic core needle breast biopsy is a reproducible and reliable alternative to surgical biopsy for histologic diagnosis of mammographic lesions. METHODS: Records from 52 consecutive patients with invasive breast cancer diagnosed by SCNBx (n = 21) or NLBx (n = 31) over 2 years were reviewed. Episode-of-care costs were extracted from the Barnes Hospital billing system database. RESULTS: At the time of excision, surgical margins were statistically more frequently positive in patients treated with NLBx (55%) than patients treated with SCNBx (0%, p < 0.0001). Furthermore, patients in the NLBx group undergoing breast conservation surgery required re-excision more frequently (74%) than those in the SCNBx group (0%, p = 0.001). There were no complications in either group after the diagnostic procedure. All SCNBx results were correct in the diagnosis of invasive breast cancer. The median cost of SCNBx was approximately $1000 less than the median cost of NLBx. This cost difference was carried through the definitive procedure, whether it was breast conservation or mastectomy. CONCLUSIONS: This study shows the advantage of SCNBx to diagnose breast cancer and definitive operative care at a single procedure. The preoperative diagnosis of breast cancer eliminated positive operative margins and procedures to re-excise breast tissue. The use of SCNBx also saved approximately $1000 per patient compared with the use of NLBx. Our data suggest that SCNBx is the diagnostic procedure of choice for mammographically detected cancers.

Adenocarcinoma↗

PubMed1996

Gene expression and cytopathic effect of vaccinia virus inactivated by psoralen and long-wave UV light.

Induction of the cytopathic effect (CPE) in cells infected with poxvirus seems ubiquitous in that it has been associated with all different strains and preparations of poxviruses, regardless of the replicating status of these viruses. The study of the mechanisms by which CPE is induced by nonreplicating poxviruses is hampered by the lack of any noncytopathic mutant strains and preparations. In this paper, we report on the patterns of gene expression and induction of CPE by vaccinia viruses treated by limited cross-linking with psoralen and long-wave UV light (PLWUV). We show that treatment of cell-free virus with PLWUV could inactivate viral replication without abolishing the ability of the virus to infect cells. Viral transcription as indicated by reporter genes was generally enhanced and prolonged under early viral promoters and abolished under late promoters. Furthermore, increasing the levels of cross-linking with PLWUV resulted in a decrease and abolishment of viral expression of a large reporter gene and a concomitant loss of the induction of CPE. Cells infected with such a virus were able to express the reporter genes and proliferate. The generation of nonreplicating and noncytopathic recombinant vaccinia viruses may help in studies of the mechanisms of CPE induction by poxvirus and may facilitate the use of poxviral vectors in broader areas of research and clinical applications.

Animals↗

PubMed1995

High cytokine production and effective antitumor activity of a recombinant vaccinia virus encoding murine interleukin 12.

We have constructed a recombinant vaccinia virus (recVV), vKT0334 mIL-12, containing the genes encoding the p35 and p40 subunits of murine interleukin-12 (mIL-12). In vitro experiments demonstrated that vKT0334 mIL-12 efficiently infected a variety of murine and human tumor cell lines and produced very high amounts (1.5 micrograms/10(6) cells/24 h) of biologically active mIL-12. Mice injected s.c. with 10(6) MCA 105 sarcoma cells, followed by injection at the same site with saline or a control recVV, vKT033, containing no mIL-12 genes, all developed progressively growing tumor, whereas 60% of animals injected with vKT0334 mIL-12 remained tumor free (P < 0.0005). Furthermore, tumor growth was significantly reduced in the remaining mice treated with vKT0334 mIL-12 that did develop tumor compared with mice treated with vKT033 (P < 0.03) or saline (P < 0.0001). We conclude that recVV expressing high levels of mIL-12 offers an effective in vivo method of cytokine gene delivery and expression in tumors with subsequent antitumor effect.

Animals↗

PubMed1990

Anti-IL-6 monoclonal antibodies protect against lethal Escherichia coli infection and lethal tumor necrosis factor-alpha challenge in mice.

Potentially fatal physiologic and metabolic derangements can occur in response to bacterial infection in animals and man. Recently it has been shown that alterations in the levels of circulating cytokines such as IL-6 and TNF-alpha occur shortly after bacterial challenge. To understand better the role of IL-6 in inflammation, we investigated the effects of in vivo anti-mouse IL-6 antibody treatment in a mouse model of septic shock. Rat anti-mouse IL-6 neutralizing mAb was produced from splenocytes of an animal immunized with mouse rIL-6. This mAb, MP5-20F3, was a very potent and specific antagonist of mouse IL-6 in vitro bioactivity, demonstrated using the NFS60 myelomonocytic and KD83 plasmacytoma target cell lines, and also immunoprecipitated radiolabeled IL-6. Anti-IL-6 mAb pretreatment of mice subsequently challenged with lethal doses of i.p. Escherichia coli or i.v. TNF-alpha protected mice from death caused by these treatments. Pretreatment of E. coli-challenged mice with anti-IL-6 led to an increase in serum TNF bioactivity, in comparison to isotype control antibody, implicating IL-6 as a negative modulator of TNF in vivo. Anti-TNF-alpha treatment of mice challenged i.p. with live E. coli resulted in a 70% decrease in serum IL-6 levels, determined by immunoenzymetric assay, compared to control antibody, thereby supporting a role for TNF-alpha as a positive regulator of IL-6 levels. We conclude that IL-6 is a mediator in lethal E. coli infection, and suggest that antagonists of IL-6 may be beneficial therapeutically in life-threatening bacterial infection.

Acute-Phase Reaction↗