Agents that modulate cellular iron availability have been studied for their antitumor activity. B... more Agents that modulate cellular iron availability have been studied for their antitumor activity. Based on encouraging in vitro studies, the iron chelator deferoxamine (DFO) has been used in clinical studies to treat cancer patients. The observation that DFO induced macular edema in several cancer patients led to the present investigation of vascular endothelial growth factor (VEGF) as a possible mediator of the encountered side effects. Both normal and malignant cell lines were incubated with DFO and a variety of other iron chelators. DFO, at concentrations achievable in humans, induced a 3-5-fold increase in VEGF mRNA expression in all cell lines studied. This increased VEGF mRNA expression was dose and time dependent. A panel of structurally different iron chelators induced an even more potent increase in VEGF mRNA expression. The DFO-induced increase in VEGF mRNA expression translated into 6- and 4-fold increases in VEGF protein secretion in conditioned media of retinal pigment epithelial and C6 glioblastoma cells, respectively. These findings suggest that VEGF may act as a mediator of the side effects induced by iron chelation therapy. In addition, because VEGF is an important regulator of angiogenesis, iron chelators should be given with caution to cancer patients.
The term nonenzymatic glycation (of protein) refers to a wide variety of spontaneous reactions be... more The term nonenzymatic glycation (of protein) refers to a wide variety of spontaneous reactions between reducing sugars and protein-bound amines. This reaction has been documented in humans and plays a role in the development of diabetic complications and perhaps in some of the degenerative processes of aging. In addition to the monocarbonyl sugars and their derivatives, an additional source of glycation is alpha-dicarbonyls. Over time, nonenzymatic glycation leads to the formation of irreversible terminal products known collectively as advanced glycation end-products (AGE) and extensive data on the role of AGEs in the etiology of diabetic complications exist. Our improved ability to measure alpha-dicarbonyls and specific AGEs may provide new and more powerful tools to monitor diabetes and predict diabetic complications in the future.
Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a dimeri... more Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a dimeric M(r) 34,000-42,000 glycoprotein that possesses potent vascular permeability-enhancing and endothelial cell-specific mitogenic activities. It is synthesized by many rodent and human tumor cells and also by some normal cells. Recently we developed a sensitive and specific time-resolved immunofluorometric assay for quantifying VPF in biological fluids. We here report findings with this assay in guinea pigs and patients with both malignant and nonmalignant effusions. Line 1 and line 10 tumor cells were injected into the peritoneal cavities of syngeneic strain 2 guinea pigs, and ascitic fluid, plasma, and urine were collected at various intervals. Within 2 to 4 days, we observed a time-dependent, parallel increase in VPF, ascitic fluid volume, and tumor cell numbers in animals bearing either tumor line; in contrast, VPF was not detected in plasma or urine, even in animals with extensive tumor burdens. However, low levels of VPF were detected in the inflammatory ascites induced by i.p. oil injection. In human studies, high levels of VPF (> 10 pM) were measured in 21 of 32 effusions with cytology-documented malignant cells and in only seven of 35 effusions without cytological evidence of malignancy. Thus, VPF levels in human effusions provided a diagnostic test for malignancy with a sensitivity of 66% and a specificity of 80% (perhaps as high as 97% in that six of the seven cytology-negative patients with VPF levels > 10 pM had cancer as determined by other criteria). As in the animal tumor models, VPF was not detected in serum or urine obtained from patients with or without malignant ascites. Many nonmalignant effusions contained measurable VPF but, on average, in significantly smaller amounts than were found in malignant effusions. VPF levels in such fluids correlated strongly (p = 0.59, P < 0.001) with monocyte and macrophage content. Taken together, these data relate ascitic fluid accumulation to VPF concentration in a well-defined animal tumor system and demonstrate, for the first time, the presence of VPF in human malignant effusions. It is likely that VPF expression by tumor and mononuclear cells contributes to the plasma exudation and fluid accumulation associated with malignant and certain inflammatory effusions. The VPF assay may prove useful for cancer diagnosis as a supplement to cytology, especially in tumors that grow in the pleural lining but not as a suspension in the effusions that they induce.
Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is an angiogenic cyt... more Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is an angiogenic cytokine expressed by many human and animal tumors. Hypoxia often up-regulates VPF/VEGF expression further. To better define the role of VPF/VEGF in tumor biology, we screened tumorigenic lines for those expressing minimal constitutive and hypoxia-inducible VPF/VEGF. Human melanoma SK-MEL-2 cells best fit these criteria and formed small, poorly vascularized tumors in immunodeficient mice. We transfected SK-MEL-2 cells stably with sense or antisense mouse VPF/VEGF cDNA or with vector alone. Cells transfected with sense VPF/VEGF (V+) expressed and secreted large amounts of mouse VPF/VEGF and formed well-vascularized tumors with hyperpermeable blood vessels and minimal necrosis in nude/SCID mice. Antisense-transfected VPF/VEGF (V-) cells expressed reduced constitutive VPF/VEGF and no detectable mouse VPF/VEGF, and formed small, minimally vascularized tumors exhibiting extensive necrosis. Vector-alone transfectants (N1 cells) behaved like parental cells. V+ cells formed numerous lung tumor colonies in SCID mice, approximately 50-fold more than N1 cells, whereas V- cells formed few or none. These experiments demonstrate that VPF/VEGF promotes melanoma growth by stimulating angiogenesis and that constitutive VPF/VEGF expression dramatically promotes tumor colonization in the lung.
In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found... more In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found two potential problems, each of which may have important clinical ramifications. First, precision, though acceptable in concentrations up to 30 mg/L, was marginal in the range above 30 mg/L. Second, when EMIT values were compared with those by fluorescent polarization immunoassay (TDx), we found a good correlation but a significant proportional bias: [EMIT] = (0.877)[TDx] + 0.435 mg/L (r = 0.971). The proportional bias was much more pronounced in specimens with high creatinine values than in specimens with normal values for creatinine. It remains to be determined which method is more nearly accurate. This imprecision and proportional bias in specimens with increased creatinines lead us to conclude that the EMIT vancomycin system should be used with caution.
Previous studies have shown that accumulation of tumor ascites fluid results in large part from i... more Previous studies have shown that accumulation of tumor ascites fluid results in large part from increased permeability of peritoneal lining vessels (Nagy et al., Cancer Res., 49: 5449-5458, 1989; Nagy et al., Cancer Res., 53: 2631-2643, 1993). However, the specific microvessels rendered hyperpermeable have not been identified nor has the basis of peritoneal vascular hyperpermeability been established. To address these questions, TA3/St and MOT carcinomas, well-characterized transplantable murine tumors that grow in both solid and ascites form, were studied as model systems. Ascites tumor cells of either type were injected i.p. into syngeneic A/Jax and C3Heb/FeJ mice, and ascites fluid and plasma were collected at intervals thereafter up to 8 and 28 days, respectively. Beginning several days after tumor cell injection, small blood vessels located in tissues lining the peritoneal cavity (mesentery, peritoneal wall, and diaphragm) became hyperpermeable to several macromolecular tracers (125I-human serum albumin, FITC-dextran, colloidal carbon, and Monastral Blue B). Increased microvascular permeability correlated with the appearance in ascites fluid of vascular permeability factor (VPF), a tumor cell-secreted mediator that potently enhances vascular permeability to circulating macromolecules. VPF was measured in peritoneal fluid by both a functional bioassay and a sensitive immunofluorometric assay. The VPF concentration, total peritoneal VPF, ascites fluid volume, tumor cell number, and hyperpermeability of peritoneal lining microvessels were found to increase in parallel over time. The close correlation of peritoneal fluid VPF concentration with the development of hyperpermeable peritoneal microvessels in these two well-defined ascites tumors suggests that VPF secretion by tumor cells is responsible, in whole or in part, for initiating and maintaining the ascites pattern of tumor growth.
To determine whether serum levels of vascular permeability factor (VPF) are elevated in patients ... more To determine whether serum levels of vascular permeability factor (VPF) are elevated in patients with ovarian hyperstimulation syndrome (OHSS) and to determine if luteinizing granulosa cells may be a source of VPF. Prospective observational study. University IVF and GIFT program. Eight consecutive IVF and GIFT patients at high risk for OHSS. Vascular permeability factor concentration in serum and follicular fluid. Serum VPF was significantly higher (15.2 +/- 4.0 pM; mean +/- SEM) on day +14 in the group who developed severe OHSS compared with those who did not. Follicular fluid VPF (171.5 +/- 18.5 pM) was approximately 100-fold greater than serum (1.7 +/- 1.3 pM) or peritoneal fluid (2.5 +/- 1.3 pM) 36 hours after hCG administration. Vascular permeability factor is elevated in patients with severe OHSS and the ovary may be a source of VPF secretion.
Agents that modulate cellular iron availability have been studied for their antitumor activity. B... more Agents that modulate cellular iron availability have been studied for their antitumor activity. Based on encouraging in vitro studies, the iron chelator deferoxamine (DFO) has been used in clinical studies to treat cancer patients. The observation that DFO induced macular edema in several cancer patients led to the present investigation of vascular endothelial growth factor (VEGF) as a possible mediator of the encountered side effects. Both normal and malignant cell lines were incubated with DFO and a variety of other iron chelators. DFO, at concentrations achievable in humans, induced a 3-5-fold increase in VEGF mRNA expression in all cell lines studied. This increased VEGF mRNA expression was dose and time dependent. A panel of structurally different iron chelators induced an even more potent increase in VEGF mRNA expression. The DFO-induced increase in VEGF mRNA expression translated into 6- and 4-fold increases in VEGF protein secretion in conditioned media of retinal pigment epithelial and C6 glioblastoma cells, respectively. These findings suggest that VEGF may act as a mediator of the side effects induced by iron chelation therapy. In addition, because VEGF is an important regulator of angiogenesis, iron chelators should be given with caution to cancer patients.
The term nonenzymatic glycation (of protein) refers to a wide variety of spontaneous reactions be... more The term nonenzymatic glycation (of protein) refers to a wide variety of spontaneous reactions between reducing sugars and protein-bound amines. This reaction has been documented in humans and plays a role in the development of diabetic complications and perhaps in some of the degenerative processes of aging. In addition to the monocarbonyl sugars and their derivatives, an additional source of glycation is alpha-dicarbonyls. Over time, nonenzymatic glycation leads to the formation of irreversible terminal products known collectively as advanced glycation end-products (AGE) and extensive data on the role of AGEs in the etiology of diabetic complications exist. Our improved ability to measure alpha-dicarbonyls and specific AGEs may provide new and more powerful tools to monitor diabetes and predict diabetic complications in the future.
Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a dimeri... more Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a dimeric M(r) 34,000-42,000 glycoprotein that possesses potent vascular permeability-enhancing and endothelial cell-specific mitogenic activities. It is synthesized by many rodent and human tumor cells and also by some normal cells. Recently we developed a sensitive and specific time-resolved immunofluorometric assay for quantifying VPF in biological fluids. We here report findings with this assay in guinea pigs and patients with both malignant and nonmalignant effusions. Line 1 and line 10 tumor cells were injected into the peritoneal cavities of syngeneic strain 2 guinea pigs, and ascitic fluid, plasma, and urine were collected at various intervals. Within 2 to 4 days, we observed a time-dependent, parallel increase in VPF, ascitic fluid volume, and tumor cell numbers in animals bearing either tumor line; in contrast, VPF was not detected in plasma or urine, even in animals with extensive tumor burdens. However, low levels of VPF were detected in the inflammatory ascites induced by i.p. oil injection. In human studies, high levels of VPF (> 10 pM) were measured in 21 of 32 effusions with cytology-documented malignant cells and in only seven of 35 effusions without cytological evidence of malignancy. Thus, VPF levels in human effusions provided a diagnostic test for malignancy with a sensitivity of 66% and a specificity of 80% (perhaps as high as 97% in that six of the seven cytology-negative patients with VPF levels > 10 pM had cancer as determined by other criteria). As in the animal tumor models, VPF was not detected in serum or urine obtained from patients with or without malignant ascites. Many nonmalignant effusions contained measurable VPF but, on average, in significantly smaller amounts than were found in malignant effusions. VPF levels in such fluids correlated strongly (p = 0.59, P < 0.001) with monocyte and macrophage content. Taken together, these data relate ascitic fluid accumulation to VPF concentration in a well-defined animal tumor system and demonstrate, for the first time, the presence of VPF in human malignant effusions. It is likely that VPF expression by tumor and mononuclear cells contributes to the plasma exudation and fluid accumulation associated with malignant and certain inflammatory effusions. The VPF assay may prove useful for cancer diagnosis as a supplement to cytology, especially in tumors that grow in the pleural lining but not as a suspension in the effusions that they induce.
Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is an angiogenic cyt... more Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is an angiogenic cytokine expressed by many human and animal tumors. Hypoxia often up-regulates VPF/VEGF expression further. To better define the role of VPF/VEGF in tumor biology, we screened tumorigenic lines for those expressing minimal constitutive and hypoxia-inducible VPF/VEGF. Human melanoma SK-MEL-2 cells best fit these criteria and formed small, poorly vascularized tumors in immunodeficient mice. We transfected SK-MEL-2 cells stably with sense or antisense mouse VPF/VEGF cDNA or with vector alone. Cells transfected with sense VPF/VEGF (V+) expressed and secreted large amounts of mouse VPF/VEGF and formed well-vascularized tumors with hyperpermeable blood vessels and minimal necrosis in nude/SCID mice. Antisense-transfected VPF/VEGF (V-) cells expressed reduced constitutive VPF/VEGF and no detectable mouse VPF/VEGF, and formed small, minimally vascularized tumors exhibiting extensive necrosis. Vector-alone transfectants (N1 cells) behaved like parental cells. V+ cells formed numerous lung tumor colonies in SCID mice, approximately 50-fold more than N1 cells, whereas V- cells formed few or none. These experiments demonstrate that VPF/VEGF promotes melanoma growth by stimulating angiogenesis and that constitutive VPF/VEGF expression dramatically promotes tumor colonization in the lung.
In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found... more In evaluating the EMIT system for vancomycin used in the Cobas Bio centrifugal analyzer, we found two potential problems, each of which may have important clinical ramifications. First, precision, though acceptable in concentrations up to 30 mg/L, was marginal in the range above 30 mg/L. Second, when EMIT values were compared with those by fluorescent polarization immunoassay (TDx), we found a good correlation but a significant proportional bias: [EMIT] = (0.877)[TDx] + 0.435 mg/L (r = 0.971). The proportional bias was much more pronounced in specimens with high creatinine values than in specimens with normal values for creatinine. It remains to be determined which method is more nearly accurate. This imprecision and proportional bias in specimens with increased creatinines lead us to conclude that the EMIT vancomycin system should be used with caution.
Previous studies have shown that accumulation of tumor ascites fluid results in large part from i... more Previous studies have shown that accumulation of tumor ascites fluid results in large part from increased permeability of peritoneal lining vessels (Nagy et al., Cancer Res., 49: 5449-5458, 1989; Nagy et al., Cancer Res., 53: 2631-2643, 1993). However, the specific microvessels rendered hyperpermeable have not been identified nor has the basis of peritoneal vascular hyperpermeability been established. To address these questions, TA3/St and MOT carcinomas, well-characterized transplantable murine tumors that grow in both solid and ascites form, were studied as model systems. Ascites tumor cells of either type were injected i.p. into syngeneic A/Jax and C3Heb/FeJ mice, and ascites fluid and plasma were collected at intervals thereafter up to 8 and 28 days, respectively. Beginning several days after tumor cell injection, small blood vessels located in tissues lining the peritoneal cavity (mesentery, peritoneal wall, and diaphragm) became hyperpermeable to several macromolecular tracers (125I-human serum albumin, FITC-dextran, colloidal carbon, and Monastral Blue B). Increased microvascular permeability correlated with the appearance in ascites fluid of vascular permeability factor (VPF), a tumor cell-secreted mediator that potently enhances vascular permeability to circulating macromolecules. VPF was measured in peritoneal fluid by both a functional bioassay and a sensitive immunofluorometric assay. The VPF concentration, total peritoneal VPF, ascites fluid volume, tumor cell number, and hyperpermeability of peritoneal lining microvessels were found to increase in parallel over time. The close correlation of peritoneal fluid VPF concentration with the development of hyperpermeable peritoneal microvessels in these two well-defined ascites tumors suggests that VPF secretion by tumor cells is responsible, in whole or in part, for initiating and maintaining the ascites pattern of tumor growth.
To determine whether serum levels of vascular permeability factor (VPF) are elevated in patients ... more To determine whether serum levels of vascular permeability factor (VPF) are elevated in patients with ovarian hyperstimulation syndrome (OHSS) and to determine if luteinizing granulosa cells may be a source of VPF. Prospective observational study. University IVF and GIFT program. Eight consecutive IVF and GIFT patients at high risk for OHSS. Vascular permeability factor concentration in serum and follicular fluid. Serum VPF was significantly higher (15.2 +/- 4.0 pM; mean +/- SEM) on day +14 in the group who developed severe OHSS compared with those who did not. Follicular fluid VPF (171.5 +/- 18.5 pM) was approximately 100-fold greater than serum (1.7 +/- 1.3 pM) or peritoneal fluid (2.5 +/- 1.3 pM) 36 hours after hCG administration. Vascular permeability factor is elevated in patients with severe OHSS and the ovary may be a source of VPF secretion.
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