Biomedical subjects

H R Alexander

Publications and source records attributed to H R Alexander.

At least 37 records · Page 2Linked to original sources

PubMed2000

The angiogenesis inhibitor, endostatin, does not affect murine cutaneous wound healing.

BACKGROUND: Endostatin is a potent angiogenesis inhibitor, which is currently being used in Phase I trials as an antitumor agent. The purpose of this study was to determine whether endostatin has an effect on wound healing in a murine model. MATERIALS AND METHODS: The function of endostatin was confirmed using a human microvascular endothelial cell (HMVEC) proliferation assay in which cells are treated for 4 days with growth media plus or minus endostatin. Full-thickness incisions were made on the dorsum of athymic nude mice and closed primarily with skin staples. PVA sponges were implanted in some wounds to determine vascular ingrowth. Subsequently, mice were treated with recombinant human endostatin at 20 mg/kg/day or 50 mg/kg/dose BID versus control for a total of 14 days. On Days 2, 4, 8, 12, and 16, three mice per group had serum samples drawn and were sacrificed. Perpendicular breaking strength (N) was determined using an Instron 5540 tensometer. Wound strength was determined by dividing breaking strength by wound area (N/cm(2)). Vascular density in sponges was determined using CD31 immunohistochemistry. Serum endostatin concentrations were determined using a commercially available ELISA kit. RESULTS: Endostatin caused a significant reduction of endothelial cell proliferation after 4 days compared to media alone (72%, P = 0.031). At all time points tested, there was no statistical difference in the wound-breaking strength between endostatin and control-treated mice at either the low or high dose. Serum endostatin levels were consistently 10-fold higher in endostatin-treated mice than in controls. No differences in vascular density were seen in endostatin versus control-treated mice as determined by CD31 immunohistochemistry of PVA sponges. CONCLUSION: Therapy with human endostatin does not induce a significant decrease in breaking strength of cutaneous wounds in mice.

Animals↗

PubMed2000

Antiangiogenic gene therapy of cancer utilizing a recombinant adenovirus to elevate systemic endostatin levels in mice.

Gene therapy represents a possible alternative to the chronic delivery of recombinant antiangiogenic proteins to cancer patients. Inducing normal host tissues to produce high circulating levels of these proteins may be more effective than targeting antiangiogenic genes to tumor tissue specifically. Previously reported gene therapy approaches in mice have achieved peak circulating endostatin levels of 8-33 ng/ml. Here we report plasma endostatin levels of 1770 ng/ml after administration of a recombinant adenovirus. Growth of MC38 adenocarcinoma, which is relatively resistant to adenoviral infection, was inhibited by 40%. These findings encourage gene delivery approaches that use the host as a "factory" to produce high circulating levels of antiangiogenic agents.

Adenoviridae↗

PubMed2000

Effects of hyperthermia and tumour necrosis factor on inflammatory cytokine secretion and procoagulant activity in endothelial cells.

The application of hyperthermia (HT) and tumour necrosis factor alpha (TNF) in isolation perfusion of the limb or liver results in regression of advanced cancers confined to these regions of the body in most patients and are thought to exert anti-tumour effects primarily on tumour neovasculature. However, the individual contribution of either treatment factor on endothelial cells (EC) are not known. In this study, we investigated the in vitro effects of moderate and severe HT on human umbilical vein EC (HUVEC) with and without TNF in clinically relevant doses. HUVEC were exposed to normothermia (37 degrees C) or moderate (39 degrees C) and severe (41 degrees C) HT for 90 or 180 min with or without TNF (1 microg/ml). Cell viability, cytokine secretion (IL-6, IL-8, VEGF, ICAM-1, VCAM-1, RANTES, E-selectin, P-selectin, L-selectin, and PECAM-1), and induction of procoagulant activity as reflected in tissue factor (TF) production were assessed at the end of the treatment period and at several time points thereafter. Neither HT nor TNF exerted significant cytotoxic effects on EC at the doses and temperatures used. HT resulted in increased production of PECAM-1 with little or no additional effect when combined with TNF. TNF caused increased secretion of IL-6, IL-8, ICAM-1, and VCAM-1 with little or no additional effect from HT. Increased E-selectin and RANTES levels were observed with TNF and HT only at 24 h after treatment. HT and TNF had mainly antagonistic effects on VEGF secretion with HT causing primarily decreased production and TNF causing increased VEGF secretion under all temperatures. Most notably, there was a rapid, prolonged and synergistic peak increase in procoagulant activity when TNF and HT were used in combination compared to TNF or HT treatment alone. These results indicate that TNF and HT exert primarily independent effects on inflammatory cytokine production in EC but synergistically increase procoagulant activity as reflected in TF production. These data provide a possible mechanism for the thrombotic effects in tumour neovasculature seen following isolation perfusion with these agents and provide a rationale for their combined use in this treatment setting.

Cell Survival↗

PubMed2000

Tumour necrosis factor receptor I (p55) is upregulated on endothelial cells by exposure to the tumour-derived cytokine endothelial monocyte- activating polypeptide II (EMAP-II).

Endothelial monocyte activating polypeptide-II (EMAP-II) is an inflammatory cytokine known to have a role in neutrophil and macrophage chemotaxis and in apoptosis. It is a tumour-derived cytokine that sensitizes tumour vasculature to the effects of systemic TNF. In order to gain insight into the mechanism by which EMAP-II sensitizes vessels to TNF, we focused on its effects on TNF receptor expression. In human umbilical vein endothelial cells (HUVEC), TNF-R1 mRNA is increased four-fold following incubation with recombinant EMAP-II. Conditioned media from cell lines known to produce high levels of EMAP-II upregulated TNF-R1 but not TNF-R2 by up to twenty-fold compared to media controls and low expressing cell lines; this effect was blocked by anti-EMAP-II antibody. Recombinant EMAP-II upregulated TNF-R1 expression by approximately six-fold. Analysis of HUVEC lysates by ELISA showed increased expression of TNF-R1 within 2 h; TNF-R2 expression was unaffected by recombinant EMAP-II. Finally, immunohistochemistry of human melanomas in vivo showed that TNF-R1 staining is increased on the vessels of tumours known to express high levels of EMAP-II compared to low EMAP-II expressing tumours. These results suggest that EMAP-II upregulates TNF-R1 expression by endothelial cells both in vitro and in vivo. This induction of TNF-R1 expression may be the mechanism by which EMAP-II sensitizes tumour endothelium to the effects of TNF leading to haemorrhagic necrosis.

Animals↗

PubMed2000

Endothelial monocyte activating polypeptide II induces endothelial cell apoptosis and may inhibit tumor angiogenesis.

Endothelial monocyte activating polypeptide II (EMAP-II) is a tumor-derived cytokine with potent effects on endothelial cells in vitro and in vivo including upregulation of tissue factor and the sensitization of human melanoma to systemic TNF treatment via its effects on the tumor vasculature. We investigated the effects of EMAP-II on tumor growth, angiogenesis, vasculogenesis, and apoptosis. EMAP-II inhibited endothelial cell proliferation, vasculogenesis, and neovessel formation. In vivo growth of human melanoma lines expressing high amounts of EMAP-II demonstrated slower growth, smaller tumors, and increased amounts of tumor necrosis than those expressing lower amounts of EMAP-II. EMAP-II induced endothelial-cell-specific apoptosis via a pathway that includes upregulation of the Fas-associated death domain and downregulation of Bcl-2. EMAP-II appears to have important effects on angiogenesis and may play a role in regulating tumor vascular growth.

3T3 Cells↗

PubMed2000

Technique and results of hyperthermic isolated hepatic perfusion with tumor necrosis factor and melphalan for the treatment of unresectable hepatic malignancies.

BACKGROUND: For a variety of histologies, the liver represents the only or the dominant site of metastatic disease. Regional treatment of the liver has the theoretic advantage of maximizing drug delivery while minimizing systemic toxicity. This article describes the technique of isolated hepatic perfusion using tumor necrosis factor and melphalan under conditions of moderate hyperthermia for the treatment of unresectable liver tumors. STUDY DESIGN: Fifty patients with biopsy-proved unresectable primary or metastatic cancer to the liver were treated. Isolated hepatic perfusion was performed for 60 minutes under conditions of moderate hyperthermia during a laparotomy with inflow through the gastroduodenal artery and outflow through an isolated segment of inferior vena cava. During isolated hepatic perfusion portal and infrahepatic blood flow were shunted externally by a centrifugal pump to the axillary vein. Complete vascular isolation was confirmed intraoperatively using a continuous 131I-labeled serum albumin leak monitoring system. Operative and perfusion parameters were recorded. RESULTS: By using a standard operative technique to achieve complete vascular isolation of the liver during perfusion, there was no leak ofperfusate detected in 48 of 50 patients as determined by the continuous leak monitoring system and absence of detectable systemic tumor necrosis factor levels. Operating time, transfusion requirements, and blood loss were within the range expected for a major operative procedure. Stable hemodynamic and perfusion parameters were achieved consistently and all patients successfully completed the 60-minute perfusion. Two patients (4%) died as a result of treatment and significant tumor regression was observed in 75%. CONCLUSIONS: Isolated hepatic perfusion is a technique that can be used to deliver high doses of chemotherapy or biologic therapy regionally and without systemic exposure. By using a standard operative technique, continuous intraoperative leak monitoring, and an external veno-veno bypass circuit, this procedure can be done safely and with acceptable morbidity and mortality. This article demonstrates that sustained and complete vascular isolation of the liver can be achieved and indicates further study is warranted to better define the role of isolated hepatic perfusion in the treatment of unresectable liver tumors.

Adult↗

PubMed2000

Vaccinia as a vector for tumor-directed gene therapy: biodistribution of a thymidine kinase-deleted mutant.

Tumor-directed gene therapy, such as "suicide gene" therapy, requires high levels of gene expression in a high percentage of tumor cells in vivo to be effective. Current vector strategies have been ineffective in achieving these goals. This report introduces the attenuated (thymidine kinase (TK)-negative) replication-competent vaccinia virus (VV) as a potential vector for tumor-directed gene therapy by studying the biodistribution of VV in animal tumor models. A TK-deleted recombinant VV (Western Reserve strain) expressing luciferase on a synthetic promoter was constructed. Luciferase activity was measured in vitro after transduction of a variety of human and murine tumor cell lines and in vivo after intraperitoneal (i.p.) delivery in C57BL/6 mice with 7-day i.p. tumors (10(6) MC-38 cells). Three other in vivo tumor models were examined for tumor-specific gene expression after intravenous delivery of VV (human melanoma in nude mice, adenocarcinoma liver metastasis in immunocompetent mice, and subcutaneous sarcoma in the rat). In addition, a replication-incompetent vaccinia (1 microg of psoralen and ultraviolet light, 365 nm, 4 minutes) was tested in vitro and in vivo and compared with active virus. Luciferase activity in i.p. tumors at 4 days after i.p. injection of VV was >7000-fold higher than lung, >3000-fold higher than liver, and >250-fold higher than ovary. In addition, intravenous injection of VV resulted in markedly higher tumor luciferase activity compared with any other organ in every model tested (up to 188,000-fold higher than liver and 77,000-fold higher than lung). Inactivation of the virus resulted in negligible gene expression in vivo. In summary, VV has a high transduction efficiency in tumor cells with high levels of gene expression. The results suggest a selective in vivo replication of TK-deleted VV in tumor cells. Replication competent, TK-deleted VV appears to be an ideal vector for testing the in vivo delivery of toxic genes to tumor cells.

Animals↗

PubMed2000

Complex interactions between the replicating oncolytic effect and the enzyme/prodrug effect of vaccinia-mediated tumor regression.

Replicating viruses for cancer gene therapy have beneficial antitumor effects, however, in the setting of an enzyme/prodrug system, the interactions between these viruses and the activated agents are complex. A replicating vaccinia virus expressing the cytosine deaminase gene (VVCD), which converts the prodrug 5-FC into 5-FU, was characterized in vitro and in vivo for its antitumor effects and pathogenicity. Replicating VVCD (+/-5-FC) at various MOIs was used to infect MC38 murine colon adenocarcinoma cells. At high MOIs (>0.1) virus alone was able to kill the majority (65-90%) of cells by day 5 with no additional benefit from prodrug. At low MOIs only the effect of prodrug is seen. Cell lysates demonstrated 300-fold reduced viral recovery from cells treated with both VVCD and 5-FC compared with controls treated with virus alone. Nude mice bearing subcutaneous MC38 tumors were injected with VVCD (or control) and treated with 5FC or control. Mice injected with VVCD (with or without 5FC treatment) had smaller tumors than the controls, suggesting that replicating vaccinia alone is cytotoxic to tumors in vivo. The addition of 5-FC improved the antitumor response when a low dose of virus was injected into tumors. Also, compared with mice that received virus alone, those that received VVCD and 5FC had significantly prolonged survival from virus-mediated death. In conclusion, the addition of an enzyme/prodrug system to a replicating virus can improve the antitumor response and decrease viral pathogenicity. Gene Therapy (2000) 7, 1217-1223.

Adenocarcinoma↗

PubMed2000

Ultrasound and sestamibi scan as the only preoperative imaging tests in reoperation for parathyroid adenomas.

BACKGROUND: In an effort to determine an efficient algorithm for the evaluation of patients with parathyroid adenomas in the reoperative setting, we explored the combination of using ultrasound scans (US) and sestamibi scintigraphy as the only preoperative imaging tests. METHODS: We analyzed the outcomes of 62 consecutive patients who were treated between January 1995 and May 1999 and who were referred for persistent primary hyperparathyroidism after initial surgical exploration, at which time no abnormal parathyroid glands had been found. Although all patients underwent US, computed tomography scan, magnetic resonance imaging, and sestamibi scan, we analyzed the success of localization and reoperation using only the results of US and sestamibi scan. RESULTS: Sixty-one patients (98%) underwent curative reoperations. The sensitivity, positive predictive value, and accuracy for US were 90%, 86%, and 84%, respectively; the corresponding values for sestamibi imaging were 78%, 94%, and 74%, respectively. In 58 of 62 cases (94%) preoperative US and/or sestamibi scan accurately identified the adenoma. In 3 patients for whom combined US and sestamibi scan were inaccurate, 1 adenoma was found by intraoperative US in the strap muscle; 1 adenoma was found by blind cervical thymectomy, and 1 adenoma was found by planned sternotomy that was based on computed tomography findings. CONCLUSIONS: This study supports an algorithm of obtaining US and sestamibi scan as the initial and perhaps only preoperative localization tests for patients with primary hyperparathyroidism after failed operation, at which time no abnormal glands had been found.

Adenoma↗

PubMed2000

Clinical and genetic analysis of patients with pancreatic neuroendocrine tumors associated with von Hippel-Lindau disease.

BACKGROUND: Patients with von Hippel-Lindau disease (VHL) may develop pancreatic neuroendocrine tumors (PNETs), which can behave in a malignant fashion. We prospectively evaluated size criteria for resection of lesions and the role of genotype/phenotype analysis of germline VHL mutations in predicting clinical course. METHODS: From December 1988 through December 1999 we screened 389 patients with VHL. The diagnosis of PNET was made by pathologic analysis of tissues or by radiographic appearance. Germline mutations were determined by quantitative Southern blotting, fluorescence in situ hybridization and complete gene sequencing. RESULTS: Forty-four patients with PNETs have been identified; 25 have undergone surgical resection, 5 had metastatic disease, and 14 are being monitored. No patient who has undergone resection based on tumor size criteria has developed metastases. Patients with PNETs were more likely to have missense mutations (58%), and 4 of 5 patients (80%) with metastatic disease had mutations in exon 3 compared with 18 of 39 (46%) patients without metastatic disease. CONCLUSIONS: Imaging for detection and surgical resection based on size criteria have resulted in the successful management of VHL patients with PNETs. Analysis of germline mutations may help identify patients at risk for PNET and which patients may benefit from surgical intervention.

Adolescent↗

PubMed2000

Adrenocorticotropin-independent macronodular adrenal hyperplasia: an uncommon cause of primary adrenal hypercortisolism.

PURPOSE: To describe the imaging findings in the adrenal glands of 12 patients with adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH). MATERIALS AND METHODS: Computed tomographic (CT) and magnetic resonance (MR) imaging findings in the adrenal glands were reviewed retrospectively in 12 patients (three men, nine women) with ACTH-independent Cushing syndrome and with bilateral nonpigmented multinodular adrenal hyperplasia. The results of pituitary MR imaging, adrenal scintigraphy, and petrosal sampling were available in nine, five, and six patients, respectively. Eleven patients underwent bilateral and one patient underwent unilateral adrenalectomy. RESULTS: Eleven patients had enlarged multinodular adrenal glands: Nodules were 0.1-5.5 cm. The combined weight of both adrenal specimens for the 11 bilateral adrenalectomy specimens was 28-297 g, with a mean weight of 122 g. Glands were hypointense compared with the liver on T1-weighted images and were hyperintense on T2-weighted images. Pituitary MR imaging findings were negative in nine of nine patients. Iodomethylnorcholesterol scintigraphy showed bilateral uptake in four of five patients. Petrosal sinus sampling revealed no petrosal-to-peripheral ACTH gradients before corticotropin-releasing hormone (CRH) stimulation in six of six patients, but three patients had gradients after CRH stimulation. After undergoing bilateral or unilateral adrenalectomy, all patients were cured. CONCLUSION: AIMAH is a rare cause of ACTH-independent Cushing syndrome, with characteristic CT findings of massively enlarged multinodular adrenal glands. Bilateral adrenalectomy is indicated on the basis of clinical and CT findings.

Adrenal Glands↗

PubMed2000

Forty-eight-hour fast: the diagnostic test for insulinoma.

Insulinoma causes fasting hypoglycemia due to inappropriate insulin secretion. Its diagnosis is based on demonstrating Whipple's triad during a supervised 72-h fast. For 75 yr, the 72-h fast has been the cornerstone for the diagnosis; however, it has never been critically assessed using newer assays for insulin, C peptide, and proinsulin. Thus, the aim of the current study is to assess the need for a full 72-h fast for the diagnosis of insulinoma. Patients with suspected hypoglycemia with documented glucose concentrations below 45 mg/dL were admitted to the NIH. Data obtained during the supervised fast of patients with pathologically proven insulinoma over a 30-yr period (1970-2000) were reviewed. We identified 127 patients with insulinoma. The average age of patients was 42.7 +/- 15.9 yr, with a predominance of females (62%). 107 patients had a benign tumor, 20 had malignant insulinoma, and 15 patients had multiple endocrine neoplasia type 1. The fast was terminated due to hypoglycemia in 44 patients (42.5%) by 12 h, 85 patients (66.9%) by 24 h, and 120 (94.5%) by 48 h. Seven patients fasted beyond 48 h despite subtle neuroglycopenic symptoms and glucose and insulin concentrations diagnostic of insulinoma. Immunoreactive proinsulin was elevated at the beginning of the fast in 90% of 42 patients. Proinsulin in noninsulinoma, in contrast to insulinoma, patients is usually suppressible; therefore, samples taken in the suppressed state have the greatest diagnostic value. We conclude that with the current available insulin and proinsulin assays, the diagnosis of insulinoma can be made within 48 h. Thus, the 48-h fast should replace the 72-h fast in textbooks and hospital protocols as the new diagnostic standard.

Adolescent↗

PubMed2000

Current status of isolated hepatic perfusion with or without tumor necrosis factor for the treatment of unresectable cancers confined to liver.

Metastatic or primary unresectable cancers confined to the liver are the sole or life-limiting component of disease for many patients with colorectal cancer, ocular melanoma, neuroendocrine tumors or primary colangio- or hepatocellular carcinomas. A number of regional treatment strategies including infusional chemotherapy and local ablative therapy are under clinical development and attest to the difficulty in adequately treating this condition. Isolated hepatic perfusion (IHP) was first clinically applied over 40 years ago, but because of its technical complexity, the attendant potential morbidity, and the lack of documented efficacy, it has not gained widespread application. In light of the remarkable antitumor activity with isolated limb perfusion with tumor necrosis factor (TNF) and melphalan in patients with unresectable extremity sarcoma or in transit melanoma, this regimen has been administered via IHP at several centers worldwide for unresectable liver cancers. IHP with TNF and melphalan can result in significant regression of advanced refractory cancers confined to the liver and, with additional clinical development, will most likely be a more routinely considered option for patients with this condition.

Antineoplastic Agents↗

PubMed2000

A phase I-II study of isolated hepatic perfusion using melphalan with or without tumor necrosis factor for patients with ocular melanoma metastatic to liver.

There are no satisfactory treatment options for patients with ocular melanoma metastatic to liver, and after liver metastases are identified, median survival is only between 2 and 7 months. Because liver metastases are the sole or life-limiting component of disease in the vast majority of patients who recur, we reasoned that complete vascular isolation and perfusion of the liver might result in clinically meaningful regression of disease. Between September 1994 and July 1999, 22 patients (13 women and 9 men; mean age, 49 years) with ocular melanoma metastatic to liver were treated with a 60-min hyperthermic isolated hepatic perfusion (IHP) using melphalan alone (1.5-2.5 mg/kg, n = 11) or with tumor necrosis factor (TNF, 1.0 mg, n = 11). Via a laparotomy, IHP inflow was via the hepatic artery alone (n = 17) or hepatic artery and portal vein (n = 5) and outflow from an isolated segment of inferior vena cava. Most patients had advanced tumor burden with a mean percentage of hepatic replacement of 25% (range, 10-75%) and a median number of metastatic nodules of 25 (range, 5 to >50). Complete vascular isolation was confirmed in all patients using a continuous intraoperative leak monitoring technique with 131I radiolabeled albumin. There was one treatment mortality (5%). The overall response rate in 21 patients was 62% including 2 radiographic complete responses (9.5%) and 11 partial responses (52%). The overall median duration of response was 9 months (range, 5-50) and was significantly longer in those treated with TNF than without (14 versus 6 months, respectively; P = 0.04). Overall median survival in 22 patients was 11 months. These data indicate that a single 60-min IHP can result in significant regression of advanced hepatic metastases from ocular melanoma. TNF appears to significantly prolong the duration of response.

Adult↗

PubMed2000

Serum endostatin levels are elevated and correlate with serum vascular endothelial growth factor levels in patients with stage IV clear cell renal cancer.

Clear cell renal carcinoma (CCRC) is a highly angiogenic tumor known to secrete vascular endothelial cell growth factor (VEGF). Endostatin is an endogenous antiangiogenic agent with antitumor activity in mice. The purpose of this study was to evaluate serum levels of endostatin in normal subjects and in patients with CCRC and to examine the relationship of these levels to circulating VEGF levels. Fifteen patients (mean age, 48 years) on a clinical protocol for stage IV CCRC at the National Cancer Institute were included in the study. Archived prenephrectomy serum samples were analyzed for endostatin and VEGF concentrations. Endostatin and VEGF levels were compared with those of an age-matched group of volunteer blood donors (n = 18) using a competitive enzyme immunoassay. Data were analyzed using the Mann-Whitney U test and the Spearman rank correlation. Median serum endostatin levels were 24.6 ng/ml (range, 15.1-54.0 ng/ml) in CCRC patients versus 14.1 ng/ml (range, 1.0-19.3 ng/ml) in healthy controls (P < 0.0001). Median VEGF levels were 3.4 ng/ml (range, 0.1-11.2 ng/ml) and 2.5 ng/ml (range, 0.1-4.2 ng/ml), respectively (P = 0.065). A highly significant correlation was observed between endostatin and VEGF levels among the CCRC patients (r = 0.81, P = 0.0003) but not among controls (r = -0.22, P = 0.37). Endostatin levels are detectable in serum from healthy subjects as well as from CCRC patients. Levels are significantly elevated and correlate with VEGF levels in CCRC patients. Elucidating the nature of this correlation may lend insight into the regulation of tumor angiogenesis in patients with renal cancer.

Adenocarcinoma, Clear Cell↗

PubMed1999

Tumor-specific gene delivery using recombinant vaccinia virus in a rabbit model of liver metastases.

BACKGROUND: Several approaches to gene therapy for cancer have yielded promising results in rodent models. The translation of these results to the clinical realm has been delayed by the lack of tumor models in large animals. We investigated the pattern of transgene (i. e., foreign or introduced gene) expression and virus vector elimination after systemic gene delivery using a thymidine kinase-negative vaccinia virus in a rabbit model of disseminated liver metastases. METHODS: VX-2 rabbit carcinoma cells were maintained by serial transplantation in the thigh muscles of New Zealand White rabbits, and disseminated liver metastases were established by direct injection of tumor cells into the portal vein of the animals. Different doses of a recombinant thymidine kinase-negative vaccinia virus vector encoding the firefly luciferase reporter gene (i.e., transgene) were injected into tumor-bearing rabbits. Transgene activity in tumors and other organs was measured at multiple time points thereafter. The pattern of development of antibodies against the vaccinia virus vector was also examined. Two-tailed Student's paired t test was used for comparisons of transgene activity. RESULTS: Transgene expression was increased in tumors by at least 16-fold in comparison with expression in other tissues by day 4 after vector injection (all P<. 001) and was maintained for approximately 1 week, providing evidence of tumor-specific gene delivery in this model. Rapid elimination of the circulating vector by the host immune system was observed. Anti-vector antibodies were detectable in serum as early as day 6 and were maintained for more than 3 months. CONCLUSIONS: Tumor-specific gene delivery is possible after systemic injection of a thymidine kinase-negative vaccinia virus vector in a model of rabbit liver metastases. Although the period of transgene expression appears limited because of a rapid immune response, the therapeutic window might be sufficient for an enzyme/prodrug gene therapy approach in clinical application.

Animals↗

PubMed1999

Sensitization of tumor necrosis factor alpha-resistant human melanoma by tumor-specific in vivo transfer of the gene encoding endothelial monocyte-activating polypeptide II using recombinant vaccinia virus.

Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine with potent experimental antitumor activity. Its clinical use in cancer treatment is severely limited by its considerable toxicity after systemic administration, and it is currently confined to isolated limb and organ perfusion settings. In this report, we introduce a novel concept of TNF-alpha-based gene therapy using the TNF-sensitizing properties of endothelial cell monocyte-activating polypeptide II (EMAP-II). We hypothesized that transfer of the EMAP-II gene into established TNF-resistant human melanomas would render these tumors sensitive to subsequent systemic TNF-alpha treatment. To achieve tumor selective gene delivery, we constructed a recombinant vaccinia virus encoding the human EMAP-II gene (vvEMAP). In vitro transfection of human melanoma cells led to the production of EMAP-II by these cells. Supernatants of vvEMAP-transfected tumor cells mediated the induction of tissue factor in endothelial cells. We characterized the pattern of gene expression after systemic administration of a recombinant vaccinia virus encoding a reporter gene in a murine in vivo model of s.c. human melanoma. Gene expression in tumor tissue was increased 100-fold as compared with normal tissue, providing evidence for tumor-selective gene delivery. Finally, human melanomas in nude mice were sensitized in vivo by transferring the EMAP-II gene using vvEMAP. Subsequent systemic administration of TNF-alpha led to tumor regression and growth inhibition of these previously TNF-resistant tumors (P < 0.05). This approach using gene therapy to sensitize primarily unresponsive tumors toward TNF-alpha may enhance the usefulness of TNF-alpha in clinical treatment strategies by increasing the window for the therapeutic application of the cytokine, thus reducing the dose necessary for antitumor responses and subsequently reduce toxicity.

Animals↗

PubMed1999

Surgery to cure the Zollinger-Ellison syndrome.

BACKGROUND AND METHODS: The role of surgery in patients with the Zollinger-Ellison syndrome is controversial. To determine the efficacy of surgery in patients with this syndrome, we followed 151 consecutive patients who underwent laparotomy between 1981 and 1998. Of these patients, 123 had sporadic gastrinomas and 28 had multiple endocrine neoplasia type 1 with an imaged tumor of at least 3 cm in diameter. Tumor-localization studies and functional localization studies were performed routinely. All patients underwent surgery according to a similar operative protocol, and all patients who had surgery after 1986 underwent duodenotomy. RESULTS: The 151 patients underwent 180 exploratory operations. The mean (+/-SD) follow-up after the first operation was 8+/-4 years. Gastrinomas were found in 141 of the patients (93 percent), including all of the last 81 patients to undergo surgery. The tumors were located in the duodenum in 74 patients (49 percent) and in the pancreas in 36 patients (24 percent); however, primary tumors were found in lymph nodes in 17 patients (11 percent) and in another location in 13 patients (9 percent). The primary location was unknown in 24 patients (16 percent). Among the patients with sporadic gastrinomas, 34 percent were free of disease at 10 years, as compared with none of the patients with multiple endocrine neoplasia type 1. The overall 10-year survival rate was 94 percent. CONCLUSIONS: All patients with the Zollinger-Ellison syndrome who do not have multiple endocrine neoplasia type 1 or metastatic disease should be offered surgical exploration for possible cure.

Adult↗